CN109591882B

CN109591882B - Rear wheel steering gear, vehicle and rear wheel steering system thereof

Info

Publication number: CN109591882B
Application number: CN201710939755.1A
Authority: CN
Inventors: 梁子健; 张祖俊; 刘先华
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd
Priority date: 2017-09-30
Filing date: 2017-09-30
Publication date: 2021-05-14
Anticipated expiration: 2037-09-30
Also published as: CN109591882A

Abstract

The present disclosure relates to a rear wheel steering device, a rear wheel steering system and a vehicle, the rear wheel steering device including: the multi-stage transmission mechanism is in transmission connection with the actuating rod and is used for converting the rotary motion of the motor into the linear motion of the actuating rod along the axial direction. From this, under the user state that the vehicle turned to, the vehicle transmitted corresponding control signal for the motor according to current whole car state for the motor is rotatory and via multistage drive mechanism drive steering actuating mechanism's actuating lever along axial displacement, through the corresponding angle of rear axle knuckle drive rear wheel for the front wheel steering, in order to improve and turn to not enough or turn to excessive problem, can increase the moment of torsion through multistage drive mechanism, reduce the requirement to the rated torque of motor, make the overall structure of rear wheel steering gear rationalize, the design degree of difficulty has been reduced.

Description

Rear wheel steering gear, vehicle and rear wheel steering system thereof

Technical Field

The present disclosure relates to the field of vehicle steering systems, and more particularly, to a rear wheel steering gear, a rear wheel steering system and a vehicle.

Background

With the development of modern automobile technology and the improvement of road conditions, the requirements on the comfort, the controllability and the safety of an automobile are higher and higher, and in the prior art, in order to improve the turning flexibility, the stability of straight running of the automobile, the comfort of the automobile and the like, a rear wheel follow-up steering technology is added in the automobile steering technology. That is, according to the rear wheel steering technique, when the vehicle is at a low speed or under-steering, the rear wheels and the front wheels rotate in opposite phases, so that the turning radius is reduced and the flexibility of the vehicle is improved. When the vehicle has the tendency of oversteering, particularly high-speed tail flicking, the rear wheels and the front wheels rotate in the same phase so as to reduce the mass center slip angle of the vehicle, reduce the steady overshoot of the yaw rate of the vehicle and realize the effect of stable lane changing. The conventional rear wheel steering device is generally in primary transmission, has small transmission ratio, requires large motor torque and has the problems of large design difficulty and high development cost.

Disclosure of Invention

An object of the present disclosure is to provide a rear wheel steering gear that reduces the requirement for the rated torque of the motor and the design difficulty.

In order to achieve the above object, according to one aspect of the present disclosure, there is provided a rear wheel steering device including: the multi-stage transmission mechanism is in transmission connection with the actuating rod and is used for converting the rotary motion of the motor into the linear motion of the actuating rod along the axial direction.

According to another aspect of the present disclosure, there is also provided a vehicle rear wheel steering system including a rear wheel, a rear axle knuckle, and the rear wheel steering gear as described above, the actuating lever having both ends connected to the rear axle knuckle.

According to yet another aspect of the present disclosure, there is also provided a vehicle including the rear wheel steering system as described above.

Through the technical scheme, namely, a multi-stage transmission mechanism is arranged between the motor and the steering actuating mechanism of the rear wheel steering gear, so that the rotary motion of the motor is converted into the linear motion of the actuating rod of the steering actuating mechanism along the axial direction through the transmission of the multi-stage transmission mechanism, when the rear wheel steering gear is applied to a vehicle in a use state, the vehicle transmits a corresponding control signal to the motor according to the current whole vehicle state when the vehicle steers, so that the motor rotates, the actuating rod of the steering actuating mechanism is driven to move along the axial direction through the multi-stage transmission mechanism, the rear wheel is driven to rotate relative to the front wheel by a corresponding angle through the rear axle steering knuckle, the problems of understeer or oversteer can be improved, the torque can be increased through the multi-stage transmission mechanism, the requirement on the rated torque of the motor is reduced, and the overall structure of the rear wheel steering gear is rational, the design difficulty is reduced.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

FIG. 1 is a functional schematic diagram of a rear wheel steering system according to an embodiment of the present disclosure;

FIG. 2 is a first block diagram of a rear wheel steering gear according to a first embodiment of the present disclosure;

FIG. 3 is a structural diagram II of the rear wheel steering gear according to the first embodiment of the present disclosure;

FIG. 4 is a structural view of a rear wheel steering gear in accordance with a first embodiment of the present disclosure, in which a part of a housing is omitted in order to show an internal structure;

fig. 5 is a structural view of a rear wheel steering gear according to the first embodiment of the present disclosure;

fig. 6 is a structural view of a rear wheel steering gear according to the first embodiment of the present disclosure;

fig. 7 is a structural view of a third control arm of the rear wheel steering gear according to the first embodiment of the present disclosure;

fig. 8 is another structural view of a third control arm of the rear wheel steering gear according to the first embodiment of the present disclosure

Fig. 9 is a partially assembled cross-sectional view of a worm and gear fit clearance adjustment mechanism according to a first embodiment of the present disclosure;

fig. 10 is an exploded perspective view of a worm gear fit clearance adjustment mechanism according to a first embodiment of the present disclosure;

FIG. 11 is a front view of an adjustment ring in the worm gear fit clearance adjustment mechanism according to the first embodiment of the present disclosure;

FIG. 12 is a top view of the pair of adjustment rings of FIG. 11 taken along a plane perpendicular to the xy-axis of the page;

FIG. 13 is a bottom plan view of the adjustment ring of FIG. 11 taken in the direction of the xy-axis plane perpendicular to the plane of the paper;

FIG. 14 is a front view of the adjustment ring of FIG. 11 taken in a plane parallel to the xz axis of the paper;

FIG. 15 is a side view of the pair of adjustment rings of FIG. 11 taken in a direction perpendicular to the yz plane of the page;

FIG. 16 is a cross-sectional view of a spring ram assembly in a worm gear fit clearance adjustment mechanism according to a first embodiment of the present disclosure;

fig. 17 is a front view of a bearing housing in the worm gear fit clearance adjustment mechanism according to the first embodiment of the present disclosure;

fig. 18 is an exploded perspective view of a second linear displacement sensor according to the first embodiment of the present disclosure;

fig. 19 is an exploded perspective view of a front case portion and a rear cover portion of a second linear displacement sensor according to a first embodiment of the present disclosure;

FIG. 20 is a side view of the back cover portion of FIG. 19;

FIG. 21 is a side view of the front housing portion of FIG. 19;

fig. 22 is an assembled front view of a second linear displacement sensor according to the first embodiment of the present disclosure;

FIG. 23 is an assembled cross-sectional view of the second linear displacement sensor according to the first embodiment of the present disclosure, wherein the mating arrangement of the retainer ring and the second shaft segment receiving cavity is shown enlarged for ease of clarity;

fig. 24 is an exploded structural view of a second linear displacement sensor according to the first embodiment of the present disclosure;

fig. 25 is a schematic signal diagram of a magnetic induction chip in the forward rotation of a multi-stage magnetic ring in a second linear displacement sensor according to the first embodiment of the disclosure;

fig. 26 is a schematic signal diagram of a magnetic induction chip when a multi-stage magnetic ring is inverted in a second linear displacement sensor according to the first embodiment of the disclosure;

FIG. 27 is an exploded perspective view of a rear wheel steering gear according to a first embodiment of the present disclosure;

FIG. 28 is an exploded perspective view of a second rear wheel steering gear according to the first embodiment of the present disclosure;

fig. 29 is a fitting state diagram of the motor and the worm gear reduction mechanism according to the first embodiment of the present disclosure;

fig. 30 is a fitting state diagram of the rear wheel steering gear according to the first embodiment of the present disclosure;

FIG. 31 is an exploded perspective view of a rear wheel steering gear according to a first embodiment of the present disclosure;

FIG. 32 is a block diagram of a rear wheel steering gear in accordance with a second embodiment of the present disclosure;

FIG. 33 is a structural diagram II of a rear wheel steering gear according to a second embodiment of the present disclosure;

3 FIG. 3 34 3 is 3 a 3 cross 3- 3 sectional 3 view 3 taken 3 along 3 line 3 A 3- 3 A 3 of 3 FIG. 3 33 3; 3

Fig. 35 is an enlarged view of a portion B in fig. 33.

Description of the reference numerals

1000-motor, 1001-motor output shaft;

1100-steering actuating mechanism, 1101-actuating rod, 1102-rack, 1103-cutting surface, 1104-pressing block guide protrusion, 1105-first ball socket, 1106-first dust cover, 1107-first cushion pad, 1108-actuating rod sliding bearing;

1200-a drive gear;

1300-worm and gear speed reducing mechanism, 1301-first assembly bolt, 1302-second sealing ring, 1303-third sealing ring, 1304-fourth sealing ring, 1305-first elastic retainer ring, 1306-second elastic retainer ring, 1307-tension ring, 1308-transmission gear rolling bearing, 1309-second assembly bolt, 1-first shell, 11-worm accommodating cavity, 12-first adjusting component accommodating cavity, 13-second adjusting component accommodating cavity, 14-step wall, 15-power input component accommodating cavity, 16-first threaded hole, 17-spring ejector rod component mounting hole, 18-first shell sealing cover, 2-worm gear, 3-worm, 31-first end, 32-second end, 4-first adjusting component, 41-first self-aligning bearing, 42-adjusting ring, 421-first spherical portion, 422-second spherical portion, 423-kidney shaped hole, 424-first notch, 5-elastic piece, 51-flat plate, 52-bending plate, 6-spring ram assembly, 61-spring ram assembly housing, 611-spring ram receiving cavity, 612-opening, 62-spring, 63-ram, 64-thread, 7-second adjusting assembly, 71-second self-aligning bearing, 72-bearing seat, 721-second notch, 8-locking ring, 9-coupler, 91-first coupler gear, 92-second coupler gear, 93-sleeve, 94-first fastening screw, 95-second fastening screw 10-first fastening member; 20-a second fastener;

1400-a gear and rack fit clearance adjusting mechanism, 1401-an adjusting plug, 1402-a pressing block, 1403-a pressing block limiting groove, 1404-a pressing spring, 1405-a first sealing ring, 1406-an exhaust plug, 1407-a pressing spring baffle and 1408-an end part;

1500-rear wheel steering gear housing, 1501-actuator lever housing, 1502-mounting bracket, 1503-female threaded pin;

1600-first linear displacement sensor, 1601-first induction magnet, 1602-first sensor read head, 1603-magnet mounting block, 1604-magnet mounting block screw, 1605-first sensor read head screw;

1700-first control arm configuration, 1701-first control arm, 1702-second control arm, 1703-first ball head, 1704-first joint, 1705-adjusting nut;

1800-third control arm, 1801-bushing structure, 1802-first yoke joint, 1803-first ball joint;

1900-angle sensor, 1901-power take-off shaft, 1902-rotor, 1903-stator, 1904-angle sensor screw, 1905-angle sensor oil seal;

2000-second linear displacement sensor, 21-second linear displacement sensor shell, 211-second shaft section accommodating cavity, 2111-clamping groove, 212-first shaft section accommodating cavity, 213-torsion spring accommodating cavity, 2131-first limiting groove; 2100-front shell, 2110-first front shell portion, 2120-second front shell portion, 2130-assembly hole; 2200-rear cover, 2210-wire harness holes; 2300-a fitting; 22-a transmission shaft, 221-an expanding section, 222-a second shaft section, 223-a first shaft section, 224-a second limiting groove, 225-a clamping groove and 226-a transmission shaft cutting surface; 220-printed circuit board, 2201-wiring harness;

23-a magnetic induction chip;

24-a multistage magnetic ring, 241-a top plate, 242-a side wall and 243-a multistage magnetic ring installation cavity;

25-rolling bearings; 26-bearing retainer ring, 261-notch, 262-inclined surface; 27-shaft sleeve, 271-large diameter section, 272-small diameter section; 28-torsion spring, 281-one end, 282-other end; 29-second sensor gear, 291-drive shaft cut mating face; 210-an expansion ring; 220-printed circuit board, 2201-wiring harness; 230-plug seal structure, 2301-plug seal block, 2302-plug press plate; 240-inner ring seal; 250-a collar; 260-a third fastener; 270-outer annular seal ring; 280-a fourth fastener;

3000-motor, 3001-motor output shaft;

3100 drive nut, 3101 first rotator link, 3102 first extension, 3103 second extension;

3200-drive screw, 3201-first drive screw, 3202-second drive screw, 3203-external screw thread of screw, 3204-second drive screw connecting end, 3205-first drive screw connecting end, 3206-second ball seat, 3207-second dust cover, 3208-second cushion pad, 3209-drive screw sliding bearing;

3300-first pulley, 3400-second pulley, 3500-drive belt;

3600-a first bearing, 3700-a second bearing, 3800-a third linear displacement sensor, 3801-a third induction magnet, 3802-a third inductor reading head, 3803-a limiting block, 3900-a rear wheel steering gear shell, 3901-a rear wheel steering gear first shell, 3902-a rear wheel steering gear second shell, 3903-a first bearing limiting step surface and 3904-a second bearing limiting step surface;

4000-a frame, 4001-a front subframe, 4002-a rear subframe, 4100-a second control arm structure, 4101-a fourth control arm, 4102-a fifth control arm, 4103-a second ball head, 4104-a second joint, 4200-a second bearing limit pressure plate, 4300-an oil seal;

5001-left front wheel, 5002-right front wheel, 5003-left rear wheel, 5004-right rear wheel;

6000-whole vehicle, 7000-rear wheel steering device, 8000-rear wheel steering system control unit.

Detailed Description

The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

In the present disclosure, unless otherwise specified, use of the terms of orientation such as "inner and outer" means "inner and outer", "upper and lower" generally correspond to "upper and lower" of the vehicle with respect to the profile of the corresponding component, it being noted that the above terms of orientation are used only for explanation and illustration of the present disclosure and are not intended to be limiting.

Disclosed in the present disclosure are a rear wheel steering device, a rear wheel steering system including the rear wheel steering device, and a vehicle, wherein the rear wheel steering device of the present disclosure includes: the steering actuator 1100 comprises an actuating rod 1101 which is used for being connected with a rear axle steering knuckle so as to be capable of driving a rear wheel to steer, and the multi-stage transmission mechanism is in transmission connection with the actuating rod 1101 so as to convert the rotary motion of the motor 1000 into the linear motion of the actuating rod 1101 along the axial direction. That is, a multi-stage transmission mechanism is arranged between the motor 1000 and the steering actuator of the rear wheel steering gear, so that the rotation motion of the motor 1000 is converted into the linear motion of the actuating rod 1101 of the steering actuator along the axial direction through the transmission of the multi-stage transmission mechanism, therefore, in a use state, when the vehicle steers, the vehicle transmits a corresponding control signal to the motor according to the current whole vehicle state, so that the motor rotates and drives the actuating rod of the steering actuator to move along the axial direction through the multi-stage transmission mechanism, and then drives the rear wheel to steer to a corresponding angle relative to the front wheel through the rear axle steering knuckle, so that the problem of insufficient steering or excessive steering can be solved.

Here, as shown in fig. 1, the rear wheel steering system may include a rear wheel steering 7000 and a control unit (ECU) 8000. Rear wheel steering system control unit 8000 can be integrated on rear wheel steering 7000's motor 1000 according to the spatial arrangement condition, and rear wheel steering system control unit 8000 and its connector need design dustproof and waterproof (more than IP 67) this moment, and rear wheel steering system control unit 8000 also can stand alone and place under trunk or back row seat, need not design dustproof and waterproof this moment, nevertheless because the pencil is longer, influences control accuracy. In the vehicle steering system, when a front wheel steering system on a front subframe 4001 and a rear wheel steering system on a rear subframe 4002 are arranged, a left front wheel 5001, a right front wheel 5002, a left rear wheel 5003 and a right rear wheel 5004 are ensured to roll around the same instantaneous center in a pure rolling manner through the design of a steering trapezoid, and the Ackerman theory needs to be satisfied. When the vehicle is turning, the rear wheel steering system control unit 8000 receives a control signal 6001 (including signals of a power supply, a steering wheel angle, a vehicle speed, a yaw rate, a lateral acceleration, a longitudinal acceleration, four wheel speeds, a braking state, and the like) from the entire vehicle 6000, and after logical calculation, sends a corresponding control command 6002 to the motor 1000 in the rear wheel steering 7000, and the motor 1000 outputs a corresponding torque according to the command, converts the rotational motion of the motor 1000 into a linear motion of the actuator 1101 of the steering actuator through a multi-stage transmission mechanism, and further pushes the left rear wheel 5003 and the right rear wheel 5004 to deflect by a certain angle through a left rear knuckle and a right rear knuckle connected to the actuator 1101. The rear wheel steering device 7000 feeds back the angle information a and the actuating lever position information B of the motor 1000 to the rear wheel steering control unit 8000 in real time, the rear wheel steering system control unit 8000 feeds back the state information of the rear wheel steering device 7000 to the whole vehicle 6000, and the states of the whole vehicle, such as yaw rate, lateral acceleration, mass center lateral deviation angle and the like, after the left rear wheel 5003 and the right rear wheel 5004 deflect by a certain angle are fed back to the rear wheel steering system control unit 8000, so that a plurality of closed-loop control loops are formed. Thus, the rear wheel steering device 7000 can adjust the corner of the rear wheel according to the state of the whole vehicle, and the rear wheel and the front wheel rotate in opposite phase when the vehicle is at low speed or under-steering, so that the turning radius is reduced, and the flexibility of the vehicle is improved. When the vehicle is in oversteer trend, particularly high-speed tail flicking trend, the rear wheels and the front wheels rotate in the same phase, the mass center slip angle of the vehicle is reduced, the steady-state overshoot of the yaw rate of the vehicle is reduced, the lane change stability is realized, the straight-line running stability of the vehicle is improved, and the comfort of the vehicle can be improved.

In addition, the multi-stage transmission mechanism mentioned in the above may adopt various reasonable structures, for example, a gear transmission mechanism, a worm gear transmission mechanism, a belt transmission mechanism, a lead screw nut matching mechanism, a rack and pinion matching mechanism, or a plurality of mutually matching transmission mechanisms among the above mechanisms, etc., as long as it can function to reliably transmit the output torque of the motor to the actuating rod 1101, so that the actuating rod 1101 can move in the axial direction, and the transmission mode through the multi-stage transmission mechanism has the characteristics of labor saving in transmission and low requirement on the rated torque of the motor. The present disclosure is described below using two different embodiments of a multi-stage transmission, but these two embodiments are only for illustrating the present disclosure and are not intended to limit the present disclosure.

An embodiment in which the worm gear engagement mechanism is adopted as the multistage transmission mechanism will be described below with reference to fig. 1 to 31.

As shown in fig. 1 to 6, the multistage transmission mechanism includes a first transmission mechanism drivingly connected to a motor output shaft 1001 of the motor 1000 and a transmission gear 1200 connected to the first transmission mechanism, and the actuating rod 1101 is provided with a rack 1102 for meshing with the transmission gear 1200. Accordingly, the actuator lever 1101 can be stably driven to move in the axial direction by the engagement of the transmission gear 1200 and the rack 1102 of the actuator lever 1101. Here, the first transmission mechanism may adopt various arrangements, for example, a gear transmission manner, a worm gear transmission manner, a pulley transmission manner, etc., and in order to transmit an appropriate torque to the transmission gear 1200 so as to effectively ensure the displacement amount of the actuating rod 1101, the first transmission mechanism may optionally include a speed reduction mechanism connected to the motor output shaft 1001 of the motor 1000, and the transmission gear 1200 is disposed on the power output shaft of the speed reduction mechanism. Here, the linear-angle transmission ratio of the transmission gear 1200 and the rack 1102 may be reasonably designed according to the actual situation required for the rear wheel steering, for example, the linear-angle transmission ratio of the gear teeth may be designed to be about 40mm/r, which is not limited by the protection scope of the present disclosure. Thus, the output torque of the motor 1000 is reduced in speed and increased in pitch by the speed reduction mechanism, and then transmitted to the rack 1102 meshing with the pinion 1200 via the pinion 1200, so that the actuator lever 1101 is moved in the axial direction. Here, for example, the speed reduction mechanism is a worm gear and worm speed reduction mechanism 1300 and includes a worm 3 and a worm wheel 2 having the power output shaft, which are engaged with each other, and the worm 3 is coaxially and rotationally connected to the motor output shaft 1001. The rear wheel steering gear has the advantages of compact overall structure arrangement, small structure, high transmission speed ratio and torque, high overload bearing capacity, stable operation and good durability through the worm and gear speed reducing mechanism. The power output shaft of the worm wheel 2 can be in interference fit with the central shaft hole of the worm wheel 2 through the tension ring 1307, and the two ends of the power output shaft are axially limited through the first elastic retainer ring 1305 and the second elastic retainer ring 1306 respectively. Here, in order to ensure the reliability of the force transmission between the motor 1000 and the steering actuator, the rotation axes of the motor 1000 and the worm 3 are optionally parallel to the central axis of the actuator rod 1101. In addition, in consideration of the arrangement of the motor 1000, the installation space occupied by the first transmission mechanism is smaller, the arrangement is more compact, alternatively, the intersecting angle of the axes of the worm wheel 2 and the worm 3 can be made smaller than 90 °, for example, 75 °, and the like, which can be adapted by adjusting the helix angle of the worm wheel 2 by design, and the transmission ratio of the worm wheel 2 and the worm 3 can be designed to be about 30. In addition, in order to ensure that the rear wheel steering gear automatically locks in the rear wheel alignment state in the event of a failure caused by vehicle parking, so that the reverse transmission efficiency of the multistage transmission mechanism is kept at 0, optionally, the worm 3 is a single-headed worm and the lead angle of the worm 3 is smaller than the equivalent friction angle between the meshing wheel teeth of the worm wheel 2 and the worm 3.

In addition, optionally, the worm gear reduction mechanism 1300 includes a first housing 1 and a worm gear fit clearance adjustment mechanism provided in the first housing 1 and used for adjusting the worm 3 and the worm wheel 2. Therefore, for example, when the worm wheel 2 and the worm 3 are worn during use and the fit clearance between the worm wheel 2 and the worm 3 is too large, the fit clearance between the worm 3 and the worm wheel 2 can be adjusted through the worm wheel and worm fit clearance adjusting mechanism, so that the worm 3 and the worm wheel 2 are in a proper mesh state, the fit precision of the worm wheel 2 and the worm 3 is effectively ensured, and the impact and the wear rate between the worm wheel 3 and the worm 2 are minimized. Wherein, worm gear fit clearance adjustment mechanism can adopt multiple reasonable arrangement structure, as long as can realize adjusting the function of the fit clearance between worm wheel 2 and the worm 3.

For example, alternatively, as shown in fig. 9 to 17, the worm and gear fit clearance adjustment mechanism may adopt a structure that the worm and gear fit clearance adjustment mechanism includes a first housing 1 and is provided inside the first housing 1: the worm gear mechanism comprises a worm wheel 2, a worm 3 and bearing adjusting structures supported at two ends of the worm 3, wherein the worm wheel 2 and the worm 3 are meshed with each other, and the bearing adjusting structures are used for driving the worm 3 to move along a first adjusting direction perpendicular to the axes of the worm wheel 2 and the worm 3 so that the worm 3 can adjust a meshing clearance with the worm wheel 2 under the condition that the intersection angle of the worm 3 and the worm wheel 2 is kept unchanged. The specific arrangement structure of the bearing adjusting structure can be reasonably designed according to actual needs, and on the basis of ensuring the functions of reliably supporting two ends of the worm 3, the function of adjusting the meshing gap between the worm 3 and the worm wheel 2 by driving the worm 3 to move along the first adjusting direction on the premise that the intersection angle of the worm 3 and the worm wheel 2 is not changed can be realized. As described above, by providing the bearing adjusting structure supported at both ends of the worm 3 in the first housing 1, in the case where the worm wheel 2 and the worm 3 have too large meshing gaps due to wear caused by long-term use or the worm wheel 2 and the worm 3 have too small meshing gaps due to improper assembly, the worm 3 can be driven to move in the first adjusting direction by the bearing adjusting structure, so that the meshing gaps between the worm 3 and the worm wheel 2 are adjusted in the state where the intersection angle of the worm 3 and the worm wheel 2 is kept unchanged, the worm 3 and the worm wheel 2 are in a proper meshing state, and the matching accuracy of the worm wheel 2 and the worm 3 is effectively ensured, thereby minimizing the impact and wear rate between the worm wheel and the worm wheel, and having the effects of improving the use reliability and reducing the noise.

Optionally, the bearing adjusting structure includes a first adjusting component 4 disposed at the first end 31 and/or the second end 32 of the worm 3, and the first adjusting component 4 includes a first self-aligning bearing 41, a spherical surface fit sleeve, an adjusting ring 42 disposed on the outer peripheral surface of the first self-aligning bearing 41, and a driving part disposed on the adjusting ring 42, and the driving part is used for driving the first self-aligning bearing 41 to drive the adjusting ring 42, the worm 3 is moved along the first adjusting direction to adjust the meshing gap. Here, the first adjusting assembly 4 structured as described above may be respectively provided at the first end 31 and the first end 32 of the worm 3 to be able to more reliably ensure the adjustment accuracy of the fit clearance of the worm wheel 2 and the worm 3, or the first adjusting assembly 4 may be provided at one of the first end 31 and the first end 32 of the worm 3, and at this time, another bearing assembly capable of accommodating the displacement change of the worm 3 needs to be correspondingly provided at the other of the first end 31 and the first end 32 of the worm 3 to be able to flexibly achieve the position adjustment of the worm 3 without the occurrence of the movement interference. In addition, through arranging first self-aligning bearing 41 and adjusting ring 42 to be the spherical surface cooperation to can make first self-aligning bearing 41 can rotate round first self-aligning bearing 41's self centre of sphere in adjusting ring 42, thereby can make first self-aligning bearing 41 after the adjustment position adjust to adaptation angle in adjusting ring 42, with the normal rotation of effectively guaranteeing worm 3. The adjustment may be performed by using a variety of suitable structures for the driving member with respect to the adjusting ring 42 as long as the driving member can function to drive the first self-aligning bearing 41 to move in the adjusting ring 42 in the first adjusting direction, and the driving member may be a single rod structure, or a rod assembly composed of a plurality of parts, for example, an expansion member such as a driving cylinder. The overall structural arrangement of the adjusting mechanism can be further rationalized by the structure described above.

In order to enable the first self-aligning bearing 41 to stably move in the adjustment ring 42 in the first adjustment direction so as to avoid the change of the intersection angle of the worm 3 and the worm wheel 2 during the movement of the first self-aligning bearing 41 in the first adjustment direction, optionally, as shown in fig. 11 to 15, a waisted spherical surface is formed on the inner peripheral surface of the adjustment ring 42, the adjustment ring 42 includes two first spherical surface portions 421 corresponding in the long-axis direction and two second spherical surface portions 422 corresponding in the short-axis direction, the outer peripheral surface of the first self-aligning bearing 41 is formed as an annular spherical surface, the diameter of the first self-aligning bearing 41 is equal to the distance of the second spherical surface portions 422 in the short-axis direction and the diameter is smaller than the distance of the two first spherical surface portions 421 in the long-axis direction, the long-axis direction is the first adjustment direction, the short axis direction is perpendicular to the first adjustment direction, and the driving member is disposed on the first spherical portion 421. Thereby, in the state where the worm wheel 2 and the worm 3 are engaged, the first self-aligning bearing 41 has a clearance with the two first spherical portions 421 in the long axis direction, respectively, so that the first self-aligning bearing 41 can be moved toward the two first spherical portions 421 on both sides in the long axis direction within the self-aligning ring 42. In order to facilitate machining of the adjusting ring 42, the two first spherical portions 421 are arranged symmetrically with respect to the short axis, and the two second spherical portions 422 are arranged symmetrically with respect to the long axis, but the disclosure is not limited thereto, and the adjusting ring 42 may be configured in other arrangements.

Alternatively, the driving member is formed as one or two elastic pieces 5 disposed on the inner peripheral surface of the first spherical portion 421, the central axis of the elastic piece 5 is disposed to overlap the long axis, the elastic piece 5 is press-fitted with the first self-aligning bearing 41 and has a pre-tightening force to drive the first self-aligning bearing 41 to always have a tendency to move toward the first spherical portion 421 close to the worm wheel 2 along the long axis direction, in the case of one elastic piece 5, the elastic piece 5 is located on the first spherical portion 421 far from the worm wheel 2, and in the case of two elastic pieces 5, the two elastic pieces 5 are disposed on the two first spherical portions 421 symmetrically to each other with respect to the short axis direction. Specifically, in the case that there is one elastic sheet 5, since the first self-aligning bearing 41 has a gap with the first spherical portion 421 near the worm wheel 2 in the adjusting ring 42, even if the matching portion of the worm wheel 2 and the worm 3 is worn during long-term use, the first self-aligning bearing 41 can drive the worm 3 to automatically adjust the position toward the first spherical portion 421 near the worm wheel 2 in real time and in time in the long axis direction through the elastic sheet 5 disposed on the first spherical portion 421 far from the worm wheel 2, thereby ensuring a proper matching gap between the worm wheel 2 and the worm 3. In the case where there are two elastic pieces 5, the adjustment of the fitting clearance of the worm wheel 2 and the worm 3 is automatically achieved by the mutual fitting of the two elastic pieces 5 respectively provided on the respective first spherical portions 421.

The present disclosure is not limited thereto and the driving member may have other suitable structures. For example, alternatively, as shown in fig. 10, the driving member includes an elastic sheet 5 and a spring ram assembly 6, the elastic sheet 5 is disposed on an inner peripheral surface of one of the first spherical portions 421 close to the worm wheel 2 side, the spring ram assembly 6 is disposed on the first housing 1 in a position adjustable along the long axis direction and radially penetrates the other one of the first spherical portions 421 far from the worm wheel 2 side, an end portion of the spring ram assembly 6 and the elastic sheet 5 are respectively press-fitted with the corresponding first spherical portion 421, and a central axis of the elastic sheet 5 and a central axis of the spring ram assembly 6 overlap. Wherein, because the central axis of flexure strip 5 arranges to overlap with the central axis of spring ejector pin subassembly 6, consequently can effectively guarantee the realization that first self-aligning bearing 41 is more stable in adjustable ring 42 along the automatic adjustment position in the major axis direction through mutually supporting of flexure strip 5 and spring ejector pin subassembly 6 to reliably realize the automatic adjustment of worm 3 and worm wheel 2 fit clearance. In addition, the position of the spring push rod assembly 6 on the first housing 1 can be adjusted along the long axis direction, for example, the adjustment along the long axis direction can be realized by a threaded connection mode with the first housing 1, so that the pretightening force of the spring push rod assembly 6 and the elastic sheet 5 on the first self-aligning bearing 41 is changed according to the difference of the depths of the spring push rod assembly 6 screwed into the first housing 1, and therefore, the requirements of customers on different pretightening forces of the first self-aligning bearing 41 can be met under the condition that the adjusting mechanism disclosed by the invention is applied to different devices.

In order to facilitate the processing and assembling of the spring push rod assembly 6, optionally, as shown in fig. 16, the spring push rod assembly 6 includes a spring push rod assembly housing 61 screwed into the spring push rod assembly mounting hole 17 of the first housing 1, a spring 62 and a push rod 63 respectively mounted in the spring push rod assembly housing 61, a thread 64 is formed on a part of an outer peripheral surface of the spring push rod assembly housing 61, a spring push rod accommodating cavity 611 is formed in the spring push rod assembly housing 61, the spring push rod accommodating cavity 611 has an opening 612 facing one end of the spring push rod assembly housing 61, the push rod 63 is formed in a stepped structure, a large end of the push rod 63 is located in the spring push rod accommodating cavity 611, a small end of the push rod 63 protrudes from the opening 612 and penetrates through the first spherical portion 421 to abut against the first self-aligning bearing 41, the spring 62 has an initial pre-tightening force, and two ends of the spring 62 are respectively pressed against a bottom end of the spring push rod accommodating And a large head end of the jack 63. Here, an outer hexagonal surface 65 may be provided on one side outer peripheral surface of the spring ejector assembly housing 61 to facilitate an operator to adjust a position of the spring ejector assembly 6 in the long axis direction with respect to the first housing 1, the spring ejector assembly housing 61 of the spring ejector assembly 6 may be formed by extrusion to facilitate forming the thread 64 and the outer hexagonal surface 65, and when assembling the spring ejector assembly 6, the spring 62 and the ejector 63 may be first inserted into the spring ejector receiving cavity 611 with the large end of the spring 62 and the ejector 63 exposed to the opening 612, and then the end of the opening 612 of the spring ejector assembly housing 61 may be subjected to an upsetting process to restrain the spring 62 and the ejector 63 in the spring ejector receiving cavity 611. Thereby having the effect of low manufacturing and processing costs through the spring ram assembly 6 of simple construction as described above. The present disclosure is not limited thereto, and the spring ram assembly 6 may be formed in other structures, for example, the spring ram assembly housing 61 may be configured as a two-part housing that can be disassembled to facilitate quick assembly and disassembly of the spring ram assembly 6.

Alternatively, as shown in fig. 14, the elastic piece 5 includes a flat plate 51 and a bent plate 52 bent from two ends of the flat plate 51 toward a direction of approaching each other, the bent plate 52 is embedded in the first spherical portion 421, and the flat plate 51 is in a straight state in an unstressed state and has a gap with an inner peripheral surface of the first spherical portion 421. Here, the elastic piece 5 may be integrally formed for convenience of processing, and for example, an included angle between the two bending plates 52 and the flat plate 51 may be 30 °, and for convenience of mounting the first self-aligning bearing 41, both side surfaces of the flat plate 51 facing the first self-aligning bearing 41 may be appropriately formed with chamfers, fillets, and the like. However, the present disclosure is not limited to the shape of the elastic sheet 5, and the elastic sheet 5 may be formed in an arc shape.

Alternatively, as shown in fig. 9 and 10, the first adjusting component 4 is disposed at the first end 31 of the worm 3, the bearing adjusting structure includes a second adjusting component 7 disposed at the first end 32 of the worm 3, the second adjusting component 7 includes a second self-aligning bearing 71 and a bearing seat 72 disposed on an outer peripheral surface of the second self-aligning bearing 71 in a spherical fit manner, and the bearing seat 72 is mounted in the second adjusting component accommodating cavity 13 of the first housing 1. Therefore, the fit clearance of the worm 3 can be reliably adjusted on the premise of not changing the intersection angle of the worm 3 and the worm wheel 2 in the process of automatically adjusting the fit clearance between the worm 3 and the worm wheel 2 through the common fit of the first adjusting component 4 and the second adjusting component 7. Here, the first self-aligning bearing 41 is optionally mounted in an axially adjustable position in the first adjusting unit accommodating chamber 12 of the first housing 1 via the adjusting ring 42, and a waist-shaped hole 423 extending in the axial direction and used for inserting the spring plunger assembly 6 is formed in the first spherical surface portion 421 of the adjusting ring 42 on the side away from the worm wheel 2, and the inner circumferential surface of the waist-shaped hole 423 is engaged with the outer circumferential surface of the plunger 63 of the spring plunger assembly 6. Wherein it can be ensured that the elastic piece 5, the kidney hole 423, and the line connecting the centers of the two first spherical portions 421 can be arranged on a straight line, thereby ensuring that the axis of the jack 63 is parallel to the straight line. That is, when the first self-aligning bearing 41 moves between the two first spherical portions 421 of the adjusting ring 42 along the long axis direction through the cooperation of the spring jack assembly 6 and the elastic piece 5, the actual moving state of the worm 3 is that the first end 32 of the worm 3 is used as a rotation point to perform a slight rotation, and at this time, the second adjusting assembly 7 generates a slight displacement change in the axial direction, and the problem of a slight inclination of the axis through a rotation lower than the worm 3 occurs, and the first self-aligning bearing 41 and the second self-aligning bearing 71 can adapt to the position change of the worm 3, which is caused by the slight inclination of the axis due to the rotation, through the spherical engagement of the first self-aligning bearing 41 in the adjusting ring 42 and the spherical engagement of the second self-aligning bearing 71 in the bearing seat 72. In addition, the first self-aligning bearing 41 of the first adjusting assembly 4 can be arranged in the first adjusting assembly accommodating cavity 12 by using the adjusting ring 42 to be capable of adjusting the position along the axial direction, so that the position change of the first end 31 of the worm 3 can be adapted. In addition, by forming the waist-shaped hole 423 on the first spherical portion 421, the adjusting ring 42 can be allowed to move axially relative to the post rod 63 when the post rod 63 of the spring post rod assembly 6 is inserted into the waist-shaped hole 423, and at this time, the post rod 63 can also play a role in guiding the axial movement of the adjusting ring 42 through the cooperation with the first spherical portion 421.

Alternatively, in order to be able to mainly play a role in reliably ensuring radial support for the worm shaft 3 and reducing rotational friction, the first self-aligning bearing 41 and the second self-aligning bearing 71 are respectively formed as deep groove ball bearings having an outer spherical surface.

Alternatively, as shown in fig. 11, first notches 424 symmetrical to each other with respect to the central axis of the adjustment ring 42 are formed on an inner circumferential surface of one end of the adjustment ring 42 to facilitate the first self-aligning bearing 41 to be radially inserted and fitted into the adjustment ring 42. Correspondingly, optionally, a second gap 721 symmetrical to each other with respect to the central axis of the bearing seat 72 is formed on the inner peripheral surface of one end of the bearing seat 72 so that the second self-aligning bearing 71 is inserted and fitted into the bearing seat 72 in the radial direction. However, the present disclosure is not limited thereto, and the adjusting ring 42 and the first self-aligning bearing 41, the bearing housing 72 and the second self-aligning bearing 71 may be individually assembled into an integral structure at the time of manufacture.

Alternatively, as shown in fig. 9, the first housing 1 includes a worm wheel accommodating cavity for accommodating the worm wheel 2 and being a closed end of the first housing 1, a worm accommodating cavity 11 for accommodating the worm 3, a first adjusting member accommodating cavity 12 for accommodating the first adjusting member 4, a second adjusting member accommodating cavity 13 for accommodating the second adjusting member 7 and being an open end of the first housing 1, and a power input member accommodating chamber 15 having a stepped wall 14 formed with the second regulating-assembly accommodating chamber 13, a first screw hole 16 is formed in an inner peripheral surface of an end portion of the second regulation member accommodation chamber 13 adjacent to the stepped wall 14, the second adjustment assembly 7 is positioned by the engagement of a locking ring 8 formed with an external thread with the first threaded hole 16, the first end 32 of the worm 3 penetrates the locking ring 8 and is mounted with the coupling 9 by means of the first fastening member 10. Here, the first housing 1 seals the worm wheel receiving cavity by a first housing sealing cover 18 to serve as a closed end of the first housing 1, a third sealing ring 1303 may be disposed at a junction of the first housing 1 and the first housing sealing cover 18, an open end of the worm wheel receiving cavity of the first housing 1 corresponding to the closed end may be connected to the actuator rod housing 1501 by a second assembling bolt 1309, and a fourth sealing ring 1304 may be disposed at a junction of the two. In this state, the transmission gear 1200 mounted on the power output shaft of the worm wheel 2 is located in the actuator lever housing 1501 and the end of the power output shaft of the worm wheel 2 is rotatably supported in the actuator lever housing 1501 by the transmission gear rolling bearing 1308. Therefore, the overall structure arrangement of the worm and gear fit clearance adjusting mechanism is compact and more reasonable.

Alternatively, as shown in fig. 28, the motor output shaft 1001 end of the motor 1000 and the second end 32 of the worm 3 are connected by a coupling 9, and the coupling 9 includes a first coupling gear 91 that is in a form-fit with the second end 32 of the worm 3, a second coupling gear 92 that is in a form-fit with the motor output shaft end of the motor 1000, and a sleeve 93 for connecting the first coupling gear 91 and the second coupling gear 92. Here, the first housing 1 may be connected to a housing of the motor 1000 by a first assembly bolt 1301, and a second sealing ring 1302 for waterproofing may be provided at a connection portion of the two. The first coupling gear 91 can be fixed on the second end 32 of the worm 3 by a first fastening screw 94, the second coupling gear 92 can also be fixed on the end of the motor output shaft 1001 of the motor 1000 by a second fastening screw 95, the sleeve 93 can be made of an ethylene propylene diene monomer (epdm) rubber material, the first coupling gear 91 and the second coupling gear 92 are connected into a whole by a tooth-shaped structure in the sleeve 93, and a crossed angle can be allowed between the axis of the first coupling gear 91 and the axis of the second coupling gear 92, so that the coupling 9 has the effects of buffering, damping and improving the dynamic performance of a shaft system.

Further, optionally, as shown in fig. 27, the rear wheel steering device includes a rack-and-pinion fit clearance adjustment mechanism 1400 for adjusting a meshing clearance between the pinion 1200 and the rack 1102. Therefore, the meshing gap between the transmission gear 1200 and the rack 1102 is adjusted by the gear-rack fit gap adjusting mechanism 1400, so that the two are ensured to operate in a proper fit gap state, and the precision of the axial movement displacement of the actuating rod 1101 is ensured. The rack-and-pinion fit clearance adjusting mechanism 1400 may be formed in various suitable structures as long as the function of adjusting the meshing clearance between the pinion 1200 and the rack 1102 is achieved.

Here, in a state where the transmission gear 1200 is disposed in the coaxial connection of the worm wheel of the worm and gear reduction mechanism having the above-described structure, in order to adjust the meshing gap between the transmission gear 1200 and the rack 1102 in a state where the fit gap between the worm wheel 2 and the worm 3 is not changed, the purpose of enabling the rack and pinion fit gap adjustment structure 1400 and the worm and gear fit gap adjustment mechanism to independently realize gap adjustment without being affected by a change in the adjustment position is achieved. Optionally, the rack-and-pinion fit clearance adjusting mechanism 1400 includes an adjusting plug 1401 and a pressing block 1402 mounted on the adjusting plug 1401, the adjusting plug 1401 is mounted on an actuating rod housing 1501 in a position adjustable along a second adjusting direction, the actuating rod 1101 is mounted in the actuating rod housing 1501, a part of the actuating rod 1101 facing away from the rack 1102 is formed with a cutting surface 1103 extending along an axial direction of the actuating rod 1101 for fitting with an end 1408 of the pressing block 1402, and the actuating rod 1101 is movable along the axial direction relative to the pressing block 1402 through the cutting surface 1103. Wherein the second adjustment direction may be a direction perpendicular to the axis of the actuator rod 1101 and the axis of the drive gear 1200. Here, in order to facilitate the assembling and disassembling of the rack and pinion fit gap adjustment mechanism, an external thread structure that is screw-fitted to the mounting hole of the actuator housing 1501 may be formed on a part of the outer circumferential surface of the adjuster plug 1401, and the adjuster plug 1401 is not formed with a hexagonal boss that is easily assembled and disassembled using a socket tool.

In order to prevent the compact heap 1402 from interfering with the actuator 1101 while guiding the actuator 1101 in the process of moving the actuator 1101 in the axial direction, optionally, a compact heap guide protrusion 1104 or a compact heap guide groove protruding or recessed in the axial direction of the actuator 1101 is formed on the cutting surface 1103, and the end 1408 of the compact heap 1402 is formed in a shape matching with the compact heap guide protrusion 1104 or the compact heap guide groove. For example, the cutting surface 1103 may be formed with a protruding compact guide projection 1104, and the end 1408 of the compact 1402 may be formed as a guide groove that mates with the compact guide projection 1104. In order to ensure that the end 1408 of the pressing block 1402 always keeps a pressed state with the cutting surface 1103 of the actuating lever 1103 so that the rack 1102 of the actuating lever 1101 maintains a preset gap with the transmission gear 1200, optionally, a pressing block limiting groove 1403 for limiting the pressing block 1402 is formed on the adjusting plug 1401, and a pressing spring 1404 is arranged between the bottom end of the pressing block limiting groove 1403 and the pressing block 1402 so that the end 1408 of the pressing block 1402 always keeps a pressed state on the cutting surface 1103. Wherein, a pressing spring stop piece 1407 can be arranged in the pressing block limiting groove 1403, and the pressing spring 1404 can be located in the accommodating cavity at the joint of the pressing block limiting groove 1403 and the end part 1408 of the pressing block 1402 and can abut against the pressing spring stop piece 1407 and the pressing block 1402 arranged on the adjusting plug 1401. Optionally, the adjusting plug 1401 is in sealing fit with the pressing block 1402 through a first sealing ring 1405, a thread is formed on the outer peripheral surface of the adjusting plug 1401 for being in threaded fit with a gear and rack fit clearance adjusting mechanism accommodating cavity of the actuating rod housing 1501, and a vent plug 1406 is arranged at the top of the adjusting plug 1401. Thus, when the air pressure inside the actuator lever housing 1051 is too high, the air is discharged to the outside through the air vent plug 1406 provided in the stopper 1401, and dirt such as muddy water cannot enter from the outside. Although the above-described gear and rack engagement gap adjustment mechanism is disclosed, the present disclosure is not limited thereto, and the gear and rack engagement gap adjustment mechanism may be configured in another arrangement as long as the function of adjusting the meshing gap between the pinion 1200 and the rack 1102 can be achieved. For example, a simple single structure may be adopted to realize the function of adjusting the meshing gap between the transmission gear 1200 and the rack 1102, for example, by an adjusting screw that can be movably disposed on the actuating rod housing 1501 in the second adjusting direction, wherein the actuating rod housing 1501 is formed with an axially extending adjusting hole, and the extending length of the adjusting hole should be no less than the maximum moving stroke of the actuating rod 1101, so as to avoid affecting the movement of the actuating rod 1101 in the axial direction.

Optionally, the rear wheel steering comprises a displacement sensor for detecting an axial displacement of the actuator stem 1101. Here, the displacement sensor may be designed to directly detect the axial displacement of the actuator lever 1101, or may be designed to indirectly detect the axial displacement of the actuator lever 1101 by detecting another component, for example, by detecting a multi-stage transmission mechanism (rotation of a transmission gear, a worm wheel, and a worm). The displacement sensor may be implemented in various suitable manners, for example, optionally, the displacement sensor is a permanent magnet non-contact linear displacement sensor, so as to detect the axial displacement of the actuating rod 1101 in a manner that the magnetic sensing head mounted on the relatively fixed component detects the change of the magnetic field of the magnetic sensing chip on the relatively moving component.

Specifically, optionally, as shown in fig. 3 and 27, the displacement sensor is a first linear displacement sensor 1600, the first linear displacement sensor 1600 includes a first inductive magnet 1601 and a first sensor reading head 1602, the first inductive magnet 1601 is mounted on the actuating rod 1101 located in the actuating rod housing 1501 through a magnet mounting block 1603 and is capable of moving in the axial direction along with the actuating rod 1101, and the first sensor reading head 1602 is disposed on a portion of the actuating rod housing 1501 corresponding to the first inductive magnet 1601 so as to be capable of acquiring the axial displacement of the actuating rod 1101 by detecting a magnetic field change of the first inductive magnet 1601. Here, the first induction magnet 1601 may be reliably fixed to the actuator rod 1101 by first attaching the first induction magnet 1601 to the magnet attachment block 1603 and then fixing the magnet attachment block 1603 to the actuator rod 1101 by the magnet attachment block screw 1604, thereby achieving a strong assembly and protecting the first induction magnet 1601 from abrasion with the actuator rod 1101 and affecting the magnet performance. The first sensor reading head 1602 may be firmly fixed to the actuator stem housing 1501 at a position corresponding to the first induction magnet 1601 by a first sensor reading head screw 1605. However, the present disclosure is not limited thereto, and the displacement sensor may have another structure.

For example, as shown in fig. 18 to 26, the displacement sensor is a second linear displacement sensor 2000, the second linear displacement sensor 2000 includes a second linear displacement sensor casing 21, a transmission shaft 22, a rotary member, a magnetic induction chip 23 and a radially-oriented multi-stage magnetic ring 24, the transmission shaft 22 is rotatably installed in the second linear displacement sensor casing 21, a first end of the transmission shaft is exposed out of the second linear displacement sensor casing 21, the rotary member is installed on the first end of the transmission shaft and cooperates with the actuating rod 1101 for converting the linear motion of the actuating rod 1101 into the rotary motion of the transmission shaft 22, the multi-stage magnetic ring 24 is sleeved on the transmission shaft 22, the magnetic induction chip 23 is installed in the second linear displacement sensor casing 21 and is arranged at a distance corresponding to the multi-stage magnetic ring 24, when the rotating member drives the multi-stage magnetic ring 24 to rotate within a circle by the transmission shaft 22, the magnetic induction chip 23 can obtain the rotation angle of the transmission shaft 22 according to the magnetic field variation generated by the rotation of the multi-stage magnetic ring 24.

The rotating member may have any suitable structure as long as the linear motion of the actuator 1101 can be converted into the rotational motion of the transmission shaft 22 by engaging with the actuator 1101, and here, the engagement between the rotating member and the actuator 1101 may be a gear-rack engagement or other engagement method, the rotating member may be a gear, a turbine, a sprocket, or other structure, and the actuator 1101 may have an engagement structure with the rotating member, and for the sake of clarity in the present disclosure, the detailed description has been given by using a gear as the rotating member, but the scope of the present disclosure is not limited thereto. As mentioned above, by providing the rotating member at the first end of the transmission shaft 22, and sleeving the transmission shaft 22 with the multi-stage magnetic ring 24 capable of rotating together with the transmission shaft 22, magnetic induction chips 23 are arranged in the second linear displacement sensor housing 21 at intervals corresponding to the multistage magnetic ring 24, whereby, when the actuating lever 1101 moves, the rotating member engaged with the actuating lever 1101 rotates and drives the transmission shaft 22 and the multi-stage magnetic ring 24 to rotate within a circle, at this time, the magnetic induction chip 23 obtains the rotation angle of the transmission shaft 22 according to the magnetic field variation generated by the rotation of the multi-stage magnetic ring 24, namely, the magnetic induction chip 23 obtains the actual displacement of the actuator 1101 according to the amount of change of the magnetic field, this allows the actual displacement amount of the actuator 1101 to be detected in real time, and thus the effect of high detection accuracy can be achieved by the simple configuration described above.

As shown in fig. 19 and 23, optionally, the multi-stage magnetic ring 24 is sleeved on the second end of the transmission shaft 22, and the magnetic induction chip 23 is disposed near the end of the multi-stage magnetic ring 24. Here, when the actuating rod 1101 moves and changes displacement, the rotating member transmits the displacement of the actuating rod 1101 to the transmission shaft 22 to drive the multistage magnetic ring 24 to rotate, the rotation of the multistage magnetic ring 24 changes the magnetic field, and the magnetic induction chip 23 disposed near the end of the multistage magnetic ring 24 detects the amount of change of the magnetic field and further follows the amount of change of the magnetic field to obtain the actual displacement of the actuating rod 1101, thereby realizing the conversion from the rotation angle of the multistage magnetic ring 24 to the actual displacement of the actuating rod 1101. The distance between the multistage magnetic ring 24 and the magnetic induction chip 23 may be set reasonably according to the size, sensitivity, magnetic field strength, and the like of the second linear displacement sensor. For example, the center line of the magnetic induction chip 23 and the axis of the multi-stage magnetic ring 24 may be maintained within a predetermined coaxial tolerance, and the spacing between the multi-stage magnetic ring 24 and the magnetic induction chip 23 may be 1mm to 5mm, but the present disclosure is not limited thereto.

Hereinafter, the actual displacement of the actuator 1101 according to the variation of the magnetic field may be realized by the following CORDIC (Coordinate Rotation Digital Computer, chinese) algorithm, and for convenience of description of the present disclosure, the example in which the multi-stage magnetic ring 24 is a circular two-pole magnetic ring will be described.

The actual displacement Δ s of the actuator 1101 corresponds to the rotation angle Δ θ of the multistage magnetic ring 24: Δ s ═ k × Δ θ, where k is a constant. In this embodiment, the maximum lateral displacement of the actuator 1101 (which may be referred to as the absolute displacement range-s- + s) may be set to less than one turn corresponding to the rotation angle of the multi-stage magnetic ring 24. When the multistage magnetic ring 24 rotates, the magnetic induction chip 23 outputs two sinusoidal signals with the phase difference of pi/2: for the sin and cos signals, the sin signal leads the cos signal by π/2 in the forward rotation and the cos signal leads the sin signal by π/2 in the reverse rotation of the multi-stage magnetic ring 24. As shown in FIGS. 25 and 26, the zero point of the coordinates represents the midpoint 0 of the actuator lever 1101, and the lateral displacement of the actuator lever 1101 is at distances of s from the midpoint 0, which correspond to + s and-s of the displacement coordinates of the actuator lever 1101. The displacement of the actuator lever 1101 at the initial position (i.e., the midpoint 0) corresponds to the rotation angle θ 0 of the multistage magnetic ring 24, and when the multistage magnetic ring 24 is rotated in the normal direction, as shown in fig. 25, the rotation angle of the actuator lever 1101 is θ 1 when the lateral displacement is-s, and the rotation angle of the actuator lever 1101 is θ 2 when the lateral displacement is + s. When the multistage magnetic ring 24 is reversed, as shown in fig. 26, when the lateral displacement of the actuator 1101 is-s, the rotation angle of the corresponding multistage magnetic ring 24 is θ 3, and when the lateral displacement of the actuator 1101 is + s, the rotation angle of the corresponding multistage magnetic ring 24 is θ 3. Namely:

θ1+θ3＝2π

θ2+θ4＝2π

since the maximum lateral displacement of the actuating rod 1101 corresponds to a rotation angle of the multistage magnetic ring 24 of less than one turn, it is possible to obtain:

θ2-θ1＜2π

θ3-θ4＜2π

therefore, after the second linear displacement sensor detects the rotation angle Δ θ of the multistage magnetic ring 24, the actual displacement Δ s of the actuator 1101 can be obtained from Δ s — k × Δ θ. The actual displacement of the actuating lever 1101 is accurately obtained through the calculation method, so that the detection accuracy of the second linear displacement sensor is effectively ensured, and the operation reliability is improved. In addition, the second linear displacement sensor configured as described above can detect the position of any point in the absolute displacement range and detect the velocity, acceleration, and the like by a further calculation method, and can also detect the angular position, angular velocity, angular acceleration, and the like of any point in the rotation angle range using the second linear displacement sensor as an angle sensor, thereby having wide applicability.

Here, the arrangement structure between the multistage magnetic ring 24 and the magnetic induction chip 23 is not limited to the above-described embodiment, and for example, the magnetic induction chip 23 may be arranged on the second linear displacement sensor housing 21 at a distance from the outer peripheral surface of the multistage magnetic ring 24.

As shown in fig. 18, optionally, the multi-stage magnetic ring 24 includes a circular top plate 241 and a side wall 242 extending from an outer periphery of the top plate 241 toward one side, so as to form a multi-stage magnetic ring installation cavity 243 inside the multi-stage magnetic ring 24 for inserting and connecting the second end of the transmission shaft. Therefore, the second end of the transmission shaft 22 is inserted into the multi-stage magnetic ring installation cavity 243 of the multi-stage magnetic ring 24 and is tightly matched with the side wall 242, so that the multi-stage magnetic ring 24 can be reliably installed on the second end of the transmission shaft 22. Here, optionally, the multistage magnetic ring 24 is interference-fitted with the second end of the transmission shaft 22 through an expansion ring 210. The expansion ring 210 may be formed as an annular body and is provided with a concave-convex matching structure along the circumferential direction in a crossed manner, so as to ensure the interference fit between the multistage magnetic ring 24 and the second end of the transmission shaft 22. However, the present disclosure is not limited thereto, and the multistage magnetic ring 24 may also be formed in other reasonable structures, for example, may be formed in a ring shape or the like.

In order to make the magnetic field variation simple to enable the actual displacement amount of the actuator rod 1101 to be easily and quickly detected, alternatively, the multistage magnetic ring 24 is formed as a two-pole magnetic ring and is equally divided into an N-pole portion and an S-pole portion in the radial direction. However, the present disclosure is not limited thereto, and the multi-stage magnetic ring 24 may also be a four-stage magnetic ring, a six-stage magnetic ring, an eight-stage magnetic ring, etc. which are oriented in the radial direction, in which case the N pole portions and the S pole portions of the multi-stage magnetic ring 24 are alternately arranged in the radial direction.

Alternatively, as shown in fig. 18 and 22, the transmission shaft 22 is formed in a multi-step structure, the transmission shaft 22 includes a diameter-expanding section 221 and a second shaft section 222 extending from one end of the diameter-expanding section 221 and having a second end of the transmission shaft, the second shaft section 222 is supported in the second shaft section accommodating cavity 211 of the second linear displacement sensor housing 21 by a rolling bearing 25, and the rolling bearing 25 is disposed on an outer peripheral surface of the second shaft section 222 between the multi-step magnetic ring 24 and the diameter-expanding section 221. Thereby, the rolling bearing 25 serves to reliably support the drive shaft 22 in the radial direction. In order to reliably ensure the radial supporting function of the rolling bearing 25 for the transmission shaft 22, so as to avoid the phenomenon of noise and the like caused by motion interference during the rotation of the transmission shaft 22, optionally, a bearing retainer ring 26 having a notch 261 and being clamped on the inner peripheral surface of the second shaft section receiving cavity 211 is arranged between the multistage magnetic ring 24 and the rolling bearing 25, so that the rolling bearing 25 can be axially limited by the cooperation of the bearing retainer ring 26 and the inner end surface of the second shaft section receiving cavity 211. The notch 261 is designed to facilitate elastic deformation of the retainer ring 26. Optionally, an annular clamping groove 2111 is formed on the inner peripheral surface of the second shaft segment accommodating cavity 211 corresponding to the retainer ring 26, an inclined surface 262 is formed on one side surface of the retainer ring 26, the inclined surface 262 is formed to make the axial thickness of the retainer ring 26 become thinner outwards in the radial direction, the inclined surface 262 faces the multistage magnetic ring 24 and is in press fit with one side top end of the clamping groove 2111, the other side surface of the retainer ring 26 is arranged at a distance from the other side top end of the clamping groove 2111, and the retainer ring 26 is matched with the clamping groove 11 to have a radially outwards expanding pre-tightening force so as to be capable of automatically adjusting the axial position of the rolling bearing 25. With the above-mentioned structure, in the long-term use process, because the rotating member installed on the first end of the transmission shaft 22 is always kept to be matched with the actuating rod 1101 and receives the reaction force provided by the actuating rod 1101, and the reaction force is transmitted to the second end of the transmission shaft 22, so that the rolling bearing 25 presses the second axial section accommodating cavity 211 of the second linear displacement sensor housing 21 corresponding to one side end face of the rolling bearing 25, and when the one side end face of the second accommodating cavity 11 of the second linear displacement sensor housing 21 is worn, the bearing retainer ring 26 causes the inclined face 262 of the bearing retainer ring 26 to further extend radially outward into the clamping groove 2111 and abut against one side top end of the clamping groove 2111 (i.e. top end facing to the multistage magnetic ring side) due to the radially outward self elastic restoring force, so that the rolling bearing 25 can be integrally pushed to automatically adjust the axial position toward the one side end face of the second axial, the radial supporting function of the rolling bearing 25 with respect to the drive shaft 22 can thereby be further reliably ensured. However, the present disclosure is not limited thereto, and the axial position of the transmission shaft 22 in the second linear displacement sensor housing 21 may be limited by adopting other suitable structures.

Optionally, the transmission shaft 22 includes a first shaft segment 223 extending from the other end of the diameter-expanded segment 221 in the axial direction and having a first end of the transmission shaft, the first shaft segment 223 is supported in the first shaft segment accommodating cavity 212 of the second linear displacement sensor housing 21 by a bushing 27, the bushing 27 has a large diameter segment 271 and a small diameter segment 272, and the large diameter segment 271 is close to the diameter-expanded segment 221 and abuts on a step-side wall surface of the first shaft segment accommodating cavity 212. Thereby, the rotation of the propeller shaft 22 can be more stably supported radially by the cooperation of the rolling bearing 25 and the sleeve 27.

Optionally, the second linear displacement sensor further includes a torsion spring 28 for providing a pre-tightening force to the rotating member when the rotating member is engaged with the actuating rod 1101, the torsion spring 28 is sleeved on the outer circumferential surface of the transmission shaft 22 close to the rotating member, one end 281 of the torsion spring 28 is limited on the second linear displacement sensor housing 21, and the other end 282 is limited on the transmission shaft 22. It should be noted here that the pre-load force provided by the torsion spring 28 is not sufficient to push the actuating rod 1101 engaged with the rotating member to move in the axial direction. The torsion spring 28 is arranged to always provide a pretightening force in one side direction to the rotating member within the absolute displacement range of the actuating lever 1101, so that the rotating member and the actuating lever 1101 can be effectively ensured to be always kept in a tightly matched state, and the purpose of eliminating the matching gap between the rotating member and the measured shaft is achieved.

As shown in fig. 23, optionally, a torsion spring receiving cavity 213 is formed on an end surface of the second linear displacement sensor housing 21 close to the rotating element, a part of the torsion spring 28 is located in the torsion spring receiving cavity 213, a first limiting groove 2131 for limiting one end 281 of the torsion spring 28 is formed in the torsion spring receiving cavity 213, and a second limiting groove 224 extending in the axial direction for limiting the other end 282 of the torsion spring 28 is formed on an outer circumferential surface of the transmission shaft 22. Thus, the torsion spring 28 can be reliably assembled to the torsion spring receiving chamber 213 of the second linear displacement sensor housing 21 and the transmission shaft 22 by inserting and limiting the one end 281 of the torsion spring 28 into the first limiting groove 2131 and inserting and limiting the other end 282 into the second limiting groove 224. The torsion spring 28 can be pre-tensioned to the rotary member after assembly by rotating the drive shaft 22 a predetermined number of turns, for example two turns. However, the present disclosure is not limited thereto, and the torsion spring 28 may be replaced with other elastic structures, such as a V-shaped elastic sheet.

Optionally, the rotating member is a second sensor gear 29, the second sensor gear 29 being a positive fit with the drive shaft second end of the drive shaft 22. In this case, the actuator lever 1101 may be formed with a mating rack portion that exclusively engages with the second sensor gear 29, or may be directly engaged with the rack 1102 of the actuator lever 1101. Here, the positive fit means a fit manner that the second sensor gear 29 and the transmission shaft 22 do not rotate relatively, for example, the fit section of the second sensor gear 29 and the transmission shaft 22 may be a circular surface, a spline surface, a triangular surface, a quadrilateral surface, an irregular surface, etc. with a cut section, in the present embodiment, as shown in fig. 23, a transmission shaft cut surface 226 is formed on the outer peripheral surface of the transmission shaft second end of the transmission shaft 22, and a transmission shaft cut fit surface 291 corresponding to the transmission shaft cut surface 226 is formed in the central shaft hole of the second sensor gear 29, so that the transmission shaft second end of the transmission shaft 22 and the second sensor gear 29 are matched to prevent the relative rotation in the circumferential direction. The present disclosure is not particularly limited as long as the function of efficiently transmitting the rotational torque to the transmission shaft 22 can be achieved by the second sensor gear 29. In order to enable the second sensor gear 29 to be reliably limited at the second end of the transmission shaft 22 along the axial direction, optionally, the second linear displacement sensor further includes a collar 250 mounted at the second end of the transmission shaft 22 for stopping the second sensor gear 29, and a clamping groove 225 for mounting the collar 250 is formed on the outer peripheral surface of the second end of the transmission shaft 22 along the circumferential direction.

For convenience of assembly, as shown in fig. 18 to 23, optionally, the second linear displacement sensor housing 21 includes a front housing 2100 and a rear cover 2200 detachably connected, the multistage magnetic ring 24 and the transmission shaft 22 are installed in a receiving cavity of the front housing 2100, a first end of the transmission shaft 22 is exposed out of the front housing 2100, and a second end of the transmission shaft 22 is sealed in the receiving cavity by the cooperation of the rear cover 2200 and the front housing 2100. Here, the front case 2100 and the rear cover 2200 may be connected by a plurality of third fasteners 260. Alternatively, an inner annular seal 240 is provided at the junction of the front housing 2100 and the rear cover 2200, and the front housing 2100 is formed with a fitting hole 2130 for mounting to the actuator stem housing 1501, i.e., a fitting 2300 such as a bolt, a screw, etc. is inserted and fixed into the fitting hole 2130 and the mounting hole of the actuator stem housing 1501 in sequence to connect the second linear displacement sensor housing 1 and the actuator stem housing 1501, where a portion of the front housing 2100 may be inserted into the housing mounting cavity of the actuator stem housing 1501 to facilitate the engagement of the second sensor gear 29 with the actuator stem 1101. The front case 2100 includes a first front case portion 2110 detachably coupled with the rear cover 2200 and a second front case portion 2120 for insertion and coupling into a case mounting cavity of the actuator lever case 1501, the fitting hole 2130 is formed at an edge portion of the first front case portion 2110, and an outer circumferential surface of the second front case portion 2120 may be provided with an outer circumferential seal 270 for sealing engagement with the actuator lever case 1501.

Optionally, as shown in fig. 18 to 23, the multistage magnetic ring 24 is sleeved at the second end of the transmission shaft 22, the magnetic induction chip 23 is installed in the rear cover 2200 through the printed circuit board 220, and the magnetic induction chip 23 faces the end of the multistage magnetic ring 24. Specifically, the printed circuit board 220 may be mounted on the inner side surface of the rear cover 2200 by the fourth fastening member 280, the magnetic induction chip 23 is disposed at a center portion of one side of the printed circuit board 220 corresponding to the multi-stage magnetic ring 24, and the printed circuit board 220 is disposed at the other side corresponding to the rear cover 2200 with a wiring harness 2201, and the wiring harness 2201 penetrates the rear cover 2200 to be exposed to the outside of the rear cover 2200. Specifically, optionally, a harness hole 2210 for leading out a harness 2201 of the printed circuit board 220 is formed in the rear cover 2200, and the harness 2201 penetrates through the harness hole 2210 and is sealed by the plug seal structure 230. The plug sealing structure 230 may include a plug sealing block 2301 and a plug pressing plate 2302, the plug sealing block 2301 is sleeved on the wiring harness 2201 exposed out of the rear cover 2200, the plug pressing plate 2302 tightly presses and assembles the plug sealing block 2301 to the outer side surface of the rear cover 2200 corresponding to the wiring harness hole 2210, wherein the wiring harness 2201 is exposed out of the plug pressing plate 2302, and the plug pressing plate 2302 is connected to the front cover 2100 together with the rear cover 2200 through a third fastening member 260. Therefore, the overall structure of the second linear displacement sensor can be more reasonable and compact, and the second linear displacement sensor has the effects of simple structure and low manufacturing cost.

Alternatively, the rear wheel steering device includes an angle sensor 1900 provided on the power output shaft 1901 of the transmission gear 1200 for detecting the rotation angle of the transmission gear 1200. For example, in the case where the first transmission mechanism employs the worm gear reduction mechanism 1300, the angle sensor may be provided on the power output shaft of the worm wheel 2, the angle sensor 1900 may be a hall angle sensor, a resolver, a magnetic encoder, or the like, for example, in the case where the angle sensor 1900 employs a resolver, the rotor 1902 is mounted on the power output shaft 1901 of the transmission gear 1200 and rotates together with the transmission gear 1200, in this state, an angle sensor oil seal 1905 needs to be additionally installed between the transmission gear 1200 and the angle sensor 1900 to separate the angle sensor 1900 from the oil, a stator 1903 is installed on the actuator lever housing 1501 by an angle sensor screw 1904, this also enables the control unit to obtain the axial displacement amount of the actuator lever 1101 by converting the detection signal of the rotation angle of the transmission gear 1200 into a gear tooth linear angular transmission ratio.

Alternatively, as shown in fig. 2 to 6, the steering actuator 1100 includes an actuator housing 1501 for mounting to the vehicle frame 4000, the actuator 1101 is mounted in the actuator housing 1501 to be movable in the axial direction, and both ends of the actuator 1101 are exposed to both sides of the actuator housing 1501, and the steering actuator 1100 further includes a first control arm structure 1700 connected to both ends of the actuator 1101 for mounting to a rear axle knuckle. Wherein the actuating lever housing 1501 may be provided with a mounting bracket 1502 that is assembled to the vehicle frame 4000 by an internally threaded pin 1503. Here, for convenience of assembly, the rear wheel steering gear includes a rear wheel steering gear housing 1500, and the rear wheel steering gear housing 1500 may include a housing of the motor 1000, the first housing 1 of the worm gear reduction mechanism 1300, which are detachably coupled to each other. The first control arm structure 1700 may be formed in an appropriate structure to be connected to a knuckle control arm of a rear axle knuckle, or may be formed in the same structure as a knuckle control arm of a rear axle knuckle so as to be usable as a corresponding control arm of a rear axle knuckle. Here, the rear wheel steering apparatus of the present disclosure may be applied to various types of independent rear suspensions such as a multi-link suspension such as macpherson, a three-link, a four-link, a five-link, etc., a double yoke, a blade arm, a double wishbone, etc., and only a link or a control arm having an appropriate kinematic relationship among them may be disposed in place of the first control arm structure 1700 of the present disclosure, or may be applied to a non-independent suspension, but this requires appropriate deformation of the first control arm structure 1700 of the rear wheel steering apparatus of the present disclosure to correspond to a knuckle of the non-independent suspension. Optionally, both ends of the actuating rod 1101 are respectively provided with a first ball seat 1105, the first control arm structure 1700 includes a first control arm 1701 and a second control arm 1702 that are mutually screwed, one end of the first control arm 1701 is provided with a first ball 1703 that is installed in the first ball seat 1105, the other end of the first control arm 1701 is screwed with one end of the second control arm 1702 for adjusting a toe angle of a rear wheel, and the other end of the second control arm 1702 is provided with a first joint 1704 that is connected with a rear axle knuckle. Here, in the case where the first control arm structure 1700 of the rear wheel steering device is used as a knuckle toe control arm, the first control arm 1701 and the second control arm 1702 are screwed by the adjusting nut 1705, so that the overall length of the two in the axial direction can be adjusted, thereby achieving an effect of adjusting the toe angle of the rear wheel. The present disclosure is not limited thereto, and the first control arm structure 1700 may be used as a link of a knuckle or a control arm having a suitable kinematic relationship according to actual needs.

Optionally, as shown in fig. 5, each of the first ball seat bases 1105 is located at two sides of the actuating rod housing 1501 and has a preset gap with two ends of the actuating rod housing 1501 respectively and correspondingly in a rear-wheel alignment state, so that each of the first ball seat bases 1105 can stop at an end of the actuating rod housing 1501 during the axial movement of the actuating rod 1101, so as to limit a movement stroke of the actuating rod 1101. That is, the maximum moving stroke amount of the actuator lever 1101 can be determined by designing the gap between the first ball seat 1105 and the end of the actuator lever housing 1501 in the initial position state after the actuator lever 1101 is returned to the normal position, and for example, when the gaps between the first ball seats 1105 and the end of the actuator lever housing 1501 are each designed to be 10mm, the maximum stroke amount of the actuator lever 1101 moving left and right in the axial direction is 20mm, that is, the actuator lever 1101 can move left and right to 10mm in each of the left and right directions in the initial position state after being returned to the normal position, and the steering angle corresponding to the rear wheel is about 3.5 °. However, the present disclosure is not limited thereto, and the corresponding travel stroke and the corresponding rear wheel steering angle may be designed according to a specific vehicle type. In addition, in order to prevent noise and deformation from being generated when the first ball seat 1105 collides with the actuator housing 1501, a first cushion 1107 may be provided between the first ball seat 1105 and the actuator housing 1501. In order to prevent foreign matter such as dust from entering the actuator lever housing 1501 and affecting the normal operation of the actuator lever 1101, a first dust cover 1106 is provided at an end of the actuator lever housing 1501 to cover the first ball mount 1105 and the connecting portion of the first control arm 1701. Furthermore, in order to be able to reliably support the actuator lever 1101 within the actuator lever housing 1501, an actuator lever slide bearing 1108 is provided on an inner circumferential surface of an end portion of the actuator lever housing 1501, and the actuator lever 1101 passes through the actuator lever slide bearing 1108 and is movable in the axial direction.

Furthermore, optionally, as shown in fig. 7 and 8, two ends of the actuating rod 1101 are respectively provided with a U-shaped yoke seat, the first control arm structure comprises a third control arm 1800, one end of the third control arm 1800 is provided with a bushing structure 1801 hinged to the first U-shaped yoke seat, and the other end is provided with a first yoke joint 1802 or a first ball joint 1803 for connecting with a rear axle knuckle. Thus, the third control arms 1800 configured as described above are connected to both ends of the actuator lever 1101, so that the knuckle can be adapted to a different type of knuckle from the first control arm structure 1700, and the configurations of the control arms connected to both ends of the actuator lever 1101 can be selected according to actual needs.

According to another aspect of the present disclosure, there is also provided a vehicle rear wheel steering system including a rear wheel, a rear axle knuckle, and the rear wheel steering as described above, to which both ends of the actuating lever 1101 are connected.

Optionally, the steering actuator 1100 includes an actuator housing 1501 for mounting to the vehicle frame 4000, the actuator 1101 is mounted in the actuator housing 1501 to be movable in the axial direction, and both ends of the actuator 1101 are exposed to both sides of the actuator housing 1501, respectively, and the steering actuator 1100 further includes a first control arm structure 1700 connected to both ends of the actuator 1101 for mounting to the rear axle knuckle, the first control arm structure 1700 serving as a sub-knuckle control arm of the rear axle knuckle. As described above, a multi-stage transmission mechanism is disposed between the motor 1000 and the steering actuator of the rear wheel steering gear, so that the rotational motion of the motor 1000 is converted into the linear motion of the actuator rod 1101 of the steering actuator along the axial direction through the transmission of the multi-stage transmission mechanism, and the first control arm structure 1700 is driven to perform corresponding motion change, thereby achieving the steering of the rear wheel. Specifically, when the vehicle turns, the vehicle transmits a corresponding control signal to the motor 1000 according to the current vehicle state, so that the motor 1000 rotates and drives the actuating rod 1101 of the steering actuating mechanism to move axially through the multi-stage transmission mechanisms such as the worm and gear speed reducing mechanism 1300 and the transmission gear 1200, and then drives the rear wheel to turn to a corresponding angle relative to the front wheel sequentially through the first control arm structure 1700 and the rear axle steering knuckle, so that the problems of insufficient steering or excessive steering can be solved, the turning flexibility, the stability of straight running of the vehicle and the comfort of the vehicle are improved, the torque can be increased through the multi-stage transmission mechanisms, the requirement on the rated torque of the motor is reduced, the overall structure of the rear wheel steering system is rationalized, and the design difficulty is reduced.

The embodiment of the multistage transmission mechanism using the transmission gear 1200 and the worm reduction mechanism 1300 is described in detail above, and the embodiment using another transmission mechanism such as a lead screw is described below with reference to fig. 32 to 35.

As shown in fig. 32 to 35, according to another embodiment of the present disclosure, there is provided a rear wheel steering device including: the steering actuator comprises a screw nut matching mechanism which is used for being connected with a rear axle steering knuckle so as to drive a rear wheel to steer, a driving nut 3100 of the screw nut matching mechanism is rotatably supported in a rear wheel steering gear shell 3900, and the transmission mechanism is in transmission connection with the driving nut 3100 of the screw nut matching mechanism so as to convert the rotary motion of the motor 3000 into the linear motion of a driving screw 3200 of the screw nut matching mechanism along the axial direction through the driving nut 3100. Here, the transmission mechanism may be of any appropriate structure, such as a gear transmission engagement mechanism, a pulley transmission engagement mechanism, a worm and gear engagement mechanism, and the like, as long as the function of converting the rotational motion of the motor 3000 into the linear motion of the driving screw 3200 in the axial direction via the transmission mechanism and the driving nut 3100 can be achieved. By adopting the lead screw nut fitting mechanism and the transmission mechanism as described above, in the case of applying the rear wheel steering device to the rear wheel steering system, as described above, when the vehicle is steered, a rear wheel steering system control unit 8000 of a rear wheel steering system receives a control signal 6001 (including signals of a power supply, a steering wheel angle, a vehicle speed, a yaw rate, a lateral acceleration, a longitudinal acceleration, four wheel speeds, a braking state and the like) from a whole vehicle 6000, sends a corresponding control command 6002 to a motor 3000 in a rear wheel steering 7000 through logic calculation, the motor 3000 outputs a corresponding torque according to the command and converts the rotary motion of the motor 3000 into the linear motion of a driving screw rod 3200 along the axial direction through a transmission mechanism and a driving nut 3100, and then the left rear wheel 5003 and the right rear wheel 5004 are pushed to deflect by a certain angle through a left rear steering knuckle and a right rear steering knuckle connected with the driving screw 3200. The rear wheel steering device 7000 feeds back the angle information a and the actuating lever position information B of the motor 3000 to the rear wheel steering control unit 8000 in real time, the rear wheel steering system control unit 8000 feeds back the state information of the rear wheel steering device 7000 to the whole vehicle 6000, and the states of the whole vehicle, such as yaw rate, lateral acceleration, mass center lateral deviation angle and the like, after the left rear wheel 5003 and the right rear wheel 5004 deflect by a certain angle are fed back to the rear wheel steering system control unit 8000, so that a plurality of closed-loop control loops are formed. Thus, the rear wheel steering device 7000 can adjust the corner of the rear wheel according to the state of the whole vehicle, and the rear wheel and the front wheel rotate in opposite phase when the vehicle is at low speed or under-steering, so that the turning radius is reduced, and the flexibility of the vehicle is improved. When the vehicle is in oversteer trend, particularly high-speed tail flicking trend, the rear wheels and the front wheels rotate in the same phase, the mass center slip angle of the vehicle is reduced, the steady-state overshoot of the yaw rate of the vehicle is reduced, the lane change stability is realized, the straight-line running stability of the vehicle is improved, and the comfort of the vehicle can be improved. The above-described structure can improve the problem of understeer or oversteer, and improve the cornering flexibility at low speeds and the steering stability at high speeds. Through the multistage transmission mode of drive mechanism and screw nut cooperation mechanism and can realize increasing the moment of torsion, reduce the requirement to 3000 rated torque of motor, and make the overall structure rationalization of rear wheel steering gear, reduced the design degree of difficulty, in addition, can make the transmission more steady and transmission efficiency high through adopting screw nut cooperation mechanism, and have the effect that reduces wearing and tearing and improve life. In addition, the screw nut matching mechanism can adopt a sliding screw nut matching mechanism, so that the automatic locking mechanism has the advantages of simple structure, convenience in processing and low manufacturing cost, has a self-locking function, and can ensure that the rear wheel steering gear realizes automatic locking under the condition that the vehicle stops to cause failure under the condition that the rear wheel is in a centering state. However, in the case of using the rolling screw-nut matching mechanism, it is necessary to separately design a locking structure that can lock the screw-nut matching mechanism in a special state such as parking, and such a locking structure may be disposed on the motor 3000, the power output shaft of the transmission mechanism, or the like, or may be directly disposed on the drive screw of the screw-nut matching mechanism, so as to achieve a locking function.

In order to ensure that the rear wheel steering gear is automatically locked in the rear-wheel-alignment state in the event of a failure due to the vehicle being parked, so that the reverse transmission efficiency of the multi-stage transmission remains 0, the lead angle of the drive screw 3200 is optionally smaller than the equivalent friction angle between the drive nut 3100 and the drive screw 3200. Alternatively, the transmission mechanism includes a first rotating member coaxially and rotationally connected to the driving nut 3100 and a second rotating member in transmission engagement with the first rotating member, and the second rotating member is coaxially and rotationally connected to the motor output shaft 3001 of the motor 3000 so as to be able to transmit the output torque of the motor 3000 to the driving nut 3100 via the second rotating member, so that the driving nut 3100 drives the driving screw 3200 to move in the axial direction. Here, the specific structure of the first rotating member and the second rotating member can be designed appropriately according to actual needs. For example, optionally, the transmission mechanism is a belt transmission matching mechanism, the first rotating member is a first pulley 3300, the second rotating member is a second pulley 3400, the diameter of the first pulley 3300 is larger than the diameter of the second pulley 3400, and the first pulley 3300 and the second pulley 3400 are connected by a transmission belt 3500. From this, through adopting the secondary drive for the transmission is bigger, and is less to motor 3000's output torque demand, and has adopted belt drive's mode and has reduced the friction noise, has improved whole car travelling comfort. Optionally, a plurality of wedge-shaped belt grooves are formed in the circumferential direction on the outer circumferential surface of the first pulley 3300 and the outer circumferential surface of the second pulley 3400, the transmission belt is a multi-wedge belt, and the wedge-shaped belt grooves of the first pulley 3300 and the second pulley 3400 are respectively matched with the wedge teeth of the multi-wedge belt. Therefore, the stable transmission and noise reduction between the first belt wheel 3300, the second belt wheel and the transmission belt 3500 are ensured, and the effects of high transmission efficiency, impact load buffering and the like are achieved. However, the present disclosure is not limited thereto, and the first rotating member and the second rotating member may adopt other arrangement structures, for example, alternatively, the transmission mechanism is a gear transmission matching mechanism, the first rotating member is a first transmission gear, the second rotating member is a second transmission gear meshed with the first transmission gear, and the diameter of the first transmission gear is larger than that of the second transmission gear. Here, the diameter of the first transmission gear is designed to be larger than that of the second transmission gear, so that the output torque of the motor 3000 is reduced in speed and increased in pitch and then transmitted to the driving screw 3200, thereby improving the motion stability of the driving screw 3200. The function of driving the driving screw 3200 to move along the axial direction can also be realized by adopting a direct matching structure of the first transmission gear and the second transmission gear.

Optionally, the first rotating member is formed with a first shaft hole for engaging with an outer peripheral surface of the driving nut 3100, and the first rotating member is in transmission connection with the driving nut 3100. Here, the drive nut 3100 and the first rotating member are alternatively drivingly connected to each other by a connecting member, for example, by fixing the drive nut 3100 and the first rotating member by a fastening member such as a screw, or alternatively, an inner peripheral surface of the first shaft hole is in a form-fit engagement with an outer peripheral surface of the drive nut 3100. Here, the form fit is a fit that allows the drive nut 3100 and the first rotating member to rotate together without relative rotation, and for example, a fit cross section between the outer peripheral surface of the drive nut 3100 and the first shaft hole of the first rotating member may be a circular surface having a cut cross section, a spline surface, a triangular surface, a quadrangular surface, an irregular surface, or the like.

In addition, for convenience of assembly, the driving screw 3200 may optionally include a first driving screw 3201 and a second driving screw 3202 which are detachably connected, and a screw outer thread 3203 which is threadedly engaged with the driving nut 3100 is formed on an outer circumferential surface of one of the first driving screw 3201 and the second driving screw 3202. For example, alternatively, the screw male screw thread 3203 is formed on a part of the outer circumferential surface of the first drive screw 3201, and the second drive screw connecting end 3204 of the first drive screw 3201 is inserted and screwed into the first drive screw connecting end 3205 of the second drive screw 3202, thereby improving the assembling efficiency. It should be noted that when the first drive screw 3201 and the second drive screw 3202 are assembled, the first drive screw 3201 and the second drive screw 3202 are coaxially arranged to achieve smooth movement of the first drive screw 3201 and the second drive screw 3202 in the rear wheel steering housing, so that phenomena of motion interference between the axes of the first drive screw 3201 and the second drive screw 3202 and large noise and vibration caused by the motion interference and the large noise and the like caused by the included angle between the axes of the first drive screw 3201 and the second drive screw 3202 are effectively avoided.

To ensure that the axes of the first drive screw 3201 and the second drive screw 3202 remain coincident, and provides smooth, geared operation with the drive nut 3100, as shown in figures 34 and 35, alternatively, the driving nut 3100 is formed in a stepped structure and has a lead screw receiving hole for receiving the driving lead screw 3200, the drive nut 3100 includes a first rotator coupling portion 3101, a first extension portion 3102 and a second extension portion 3103, the first shaft hole of the first rotor is fitted to the outer peripheral surface of the first rotor connecting portion 3101, a nut female screw is formed on an inner peripheral surface of the first rotor connecting portion 3101 to the screw male screw 3203, the first extension 3102 extends from one end of the first rotor connecting portion 3101 and engages with the outer circumferential surface of the first drive screw 3201, the second extending portion 3103 extends from the other end of the first rotor connecting portion 3101 and engages with the outer circumferential surface of the second drive screw 3202. Here, in order to achieve reliable support of the screw nut engagement mechanism in rear wheel steering gear housing 3900, alternatively, the end of first extension 3102 is supported in rear wheel steering gear housing 3900 by first bearing 3600, the end of second extension 3103 is supported in rear wheel steering gear housing 3900 by second bearing 3700, and drive nut 3100 is axially restrained by engagement of first bearing 3600 and second bearing 3700 with rear wheel steering gear housing 3900. Optionally, the first bearing 3600 is a deep groove ball bearing, and the second bearing 3700 is a double row angular contact ball bearing. Here, the second bearing 3700 may be located at a position between the motor 3000 and the first and second rotating members, so that the overall structure is more compact and the spatial arrangement is rationalized, here, the rear wheel steering gear housing 3900 facilitates assembly of the screw nut fitting mechanism and the transmission mechanism and rationalizes the arrangement of the overall structure, which may include a detachably connected rear wheel steering first housing 3901 and rear wheel steering second housing 3902, within the rear-wheel steering first housing 3901 may be housed a first drive screw 3201 and a transmission mechanism such as a first pulley 3300, a second pulley 3400, a transmission belt 3500, a first rotor coupling portion 3101 and a first extension portion 3102 of a drive nut 3100, and the size of the drive nut receiving cavity of the rear wheel steering gear first housing 3901 is larger than the size of the first drive screw receiving cavity to form a first bearing limit step surface 3903. A second drive screw 3202 and a second extension 3103 of drive nut 3100 may be housed within rear wheel steering second housing 3902, and the drive nut receiving cavity of rear wheel steering second housing 3902 is sized larger than the second drive screw receiving cavity to form second bearing stop boss face 3904. Thus, the first bearing 3600 is mounted near the first bearing limit step surface 3903 and is primarily configured to share some of the radial force of the drive nut 3100 such that the drive nut 3100 is uniformly loaded. The two ends of the second bearing 3700 are limited in a driving nut accommodating cavity of the rear wheel steering gear second shell 3902 through the second bearing limiting boss surface 3904 and the second bearing limiting pressure plate 4200, so that the radial and axial loads are mainly borne, and the second bearing 3700 adopts a double-row angular contact ball bearing and has the advantages of small bearing friction, high rotation precision and good high-speed performance. However, the present disclosure is not limited thereto, and the specific arrangement of the first bearing 3600, the second bearing 3700, and the rear wheel steering gear housing 3900 may be appropriately designed according to actual needs. For example, the positions of the first bearing 3600 and the second bearing 3700 may be interchanged, and in this case, the function of stably supporting the screw nut engagement mechanism can be also realized. In addition, both ends of the drive nut 3100 are sealingly engaged with the drive screw 3200 via oil seals 4300, in order to prevent lubricating oil used in the screw nut engagement mechanism from being exposed to the outside.

Optionally, the rear wheel steering comprises a displacement sensor for detecting the axial displacement of the drive screw 3200. Here, the displacement sensor may be designed to directly detect the axial displacement of the driving screw 3200, or may be designed to indirectly detect the axial displacement of the driving screw 3200 by detecting other components, for example, by detecting the first rotating member, the second rotating member, and the like of the transmission mechanism. The displacement sensor may be implemented in various suitable manners, for example, optionally, the displacement sensor is a permanent magnetic non-contact linear displacement sensor, so as to detect the axial displacement of the driving screw 3200 in a manner that a magnetic sensing head mounted on a relatively fixed component detects a change in a magnetic field of a magnetic sensing chip on a relatively moving component.

For example, as shown in fig. 34 and 35, the displacement sensor may be a third linear displacement sensor 3800, the third linear displacement sensor 3800 includes a third sensing magnet 3801 and a third sensor reading head 3802, the third sensing magnet 3801 is mounted in a third sensing magnet limiting groove formed on the driving screw 3200 and is capable of moving in an axial direction along with the driving screw 3200, and the third sensor reading head 3802 is disposed on a portion of the rear wheel steering gear housing 3800 corresponding to the third sensing magnet 3801 so as to be capable of acquiring the axial displacement of the driving screw 3200 by detecting a change in a magnetic field of the third sensing magnet 3801. Here, an annular groove may be formed on a partial outer circumferential surface of the driving screw 3200, the third sensing magnet 3801 may be limited in the annular groove, and the third sensing magnet may also realize rotation limitation on the third sensing magnet 3801 by a limit block 3803 limited in the annular groove. Accordingly, the axial displacement of the drive screw 3200 can be detected by the third sensor head 3802 attached to the rear wheel steering housing 3900 so as to detect the change in the magnetic field of the third inductive magnet 3801 that moves in the axial direction together with the drive screw 3200. However, the present disclosure is not limited thereto, and the displacement sensor may also adopt other manners, for example, the second linear displacement sensor 2000 as mentioned in the first embodiment may be adopted, in this case, an engagement structure for engaging with a rotating member of the second linear displacement sensor 2000 needs to be formed at a partial position of the driving lead screw 3200, for example, in a case where the rotating member is formed as the second sensor gear 29, a rack gear engaged with the second sensor gear 29 needs to be formed at a corresponding position of the driving lead screw 3200, so that the linear motion of the driving lead screw 3200 is converted into the rotation of the multistage magnetic ring 24 by the engagement of the rack gear and the second sensor 29, so that the magnetic induction chip 23 detects the magnetic field change of the multistage magnetic ring 24 to indirectly acquire the displacement of the driving lead screw 3200. For another example, the displacement sensor may also adopt the angle sensor mentioned in the first embodiment, and may be a hall angle sensor, a rotary transformer, a magnetic encoder, or the like.

Alternatively, the driving screw 3200 is axially movably mounted in the rear wheel steering gear housing 3900, and both ends of the driving screw 3200 are exposed to both sides of the rear wheel steering gear housing 3900, and the steering actuator includes a second control arm structure 4100 connected to both ends of the driving screw 3200 for mounting to a rear axle knuckle. The second control arm structure 4100 may be formed in an appropriate structure to be connected to a knuckle control arm of a rear axle knuckle, or may be formed in the same structure as a knuckle control arm of a rear axle knuckle so as to be usable as a corresponding control arm of a rear axle knuckle. Here, the rear wheel steering apparatus of the present disclosure may be applied to various types of independent rear suspensions such as a multi-link suspension such as macpherson, a three-link, a four-link, a five-link, etc., a double yoke, a blade arm, a double wishbone, etc., only a link or a control arm having an appropriate kinematic relationship among them may be disposed instead of the second control arm structure 4100 of the present disclosure, or may be applied to a non-independent suspension, but this requires appropriate deformation of the second control arm structure 4100 of the rear wheel steering apparatus of the present disclosure to correspond to a knuckle of the non-independent suspension.

Optionally, the two ends of the driving screw 3200 are respectively provided with a second ball seat 3206, the second control arm structure 4100 comprises a fourth control arm 4101 and a fifth control arm 4102 which are connected with each other in a threaded manner, one end of the fourth control arm 4101 is provided with a second ball 4103 which is installed in the second ball seat 3206, the other end of the fourth control arm 4101 is connected with one end of the fifth control arm 4102 in a threaded manner so as to adjust the toe angle of the rear wheel, and the other end of the fifth control arm 4102 is provided with a second joint 4104 which is connected with the rear axle knuckle. Here, when the second control arm structure 4100 of the rear wheel steering device is used as the knuckle toe control arm, the overall length of the fourth control arm 4101 and the fifth control arm 4102 in the axial direction can be adjusted by the screw connection method, and the effect of adjusting the toe angle of the rear wheel can be obtained. However, the present disclosure is not limited thereto, and the second control arm structure 4100 may be used as a link of a knuckle or a control arm having an appropriate kinematic relationship according to actual needs.

Optionally, each of the second ball seat 3206 is located on two sides of the rear wheel steering gear housing 3900 and has a preset gap with two ends of the rear wheel steering gear housing 3900 in a rear wheel alignment state, respectively, so that each of the second ball seat 3206 can be stopped at the end of the rear wheel steering gear housing 3900 during the axial movement of the driving screw 3200 for limiting the movement stroke of the driving screw 3200. That is, the maximum amount of movement stroke of drive screw 3200 can be determined by designing the clearance between second ball mount 3206 and the end portion of rear wheel steering gear housing 3900 in the initial position state after the drive screw 3200 is returned to the right, and for example, when the clearances between the end portions of each of second ball mount 3206 and rear wheel steering gear housing 3900 (i.e., the corresponding rear wheel steering gear first housing 3901 and rear wheel steering gear second housing 3902, which will be described in detail below in a manner of collectively referred to as rear wheel steering gear housing 3900) are each designed to be 11.5mm, the maximum amount of movement stroke of drive screw 3200 moving leftward and rightward in the axial direction is 23mm, i.e., when drive screw 3200 can move leftward and rightward to the maximum stroke of 11.5mm from the initial position state after the return to the right, and the corresponding rear steering angle is about 2.8 °. However, the present disclosure is not limited thereto, and the corresponding travel stroke and the corresponding rear wheel steering angle may be designed according to a specific vehicle type. In order to prevent noise and deformation when the second ball mount 3206 collides with the rear wheel steering gear housing 3900, a second cushion 3208 may be provided between the second ball mount 3602 and the rear wheel steering gear housing 3900. In order to prevent foreign matter such as dust from entering the rear wheel steering housing 3900 and affecting the normal operation of the drive screw 3200, a second dust cover 3207 that covers the connecting portion of the second ball mount 3206 and the fourth control arm 4101 is provided at the end of the rear wheel steering housing 3900. Further, in order to be able to reliably support the drive screw 3200 within the rear wheel steering gear housing 3900, a drive screw sliding bearing 3209 is provided on an inner peripheral surface of an end portion of the rear wheel steering gear housing 3900, and the drive screw 3200 is passed through the drive screw sliding bearing 3209 and is movable in the axial direction. Furthermore, according to an alternative embodiment of the present disclosure, as shown in the above first embodiment, both ends of the driving screw 3200 are respectively provided with a U-shaped yoke seat, the second control arm structure comprises a third control arm 1800, one end of the third control arm 1800 is provided with a bushing structure 1801 hinged with the first U-shaped yoke seat, and the other end is provided with a first yoke joint 1802 or a first ball joint 1803 for connecting with a rear axle knuckle. Accordingly, since the third control arms 1800 configured as described above are connected to both ends of the driving screw 3200, it is possible to adapt to a different type of knuckle from the second control arm structure 4100, and it is possible to select the configuration of the control arms connected to both ends of the driving screw 3200 according to actual needs.

Based on the rear wheel steering gear of above-mentioned structure, still provide a vehicle rear wheel steering system, vehicle rear wheel steering system includes rear wheel, rear axle knuckle and as above the rear wheel steering gear, the both ends of drive screw 3200 with the rear axle knuckle is connected.

Alternatively, the driving screw 3200 is axially movably mounted in the rear wheel steering gear housing 3900, and both ends of the driving screw 3200 are exposed to both sides of the rear wheel steering gear housing 3900, and the steering actuator includes a second control arm structure 4100 connected to both ends of the driving screw 3200 for mounting to the rear axle knuckle, the second control arm structure 4100 serving as a sub-knuckle control arm of the rear axle knuckle. As described above, the transmission mechanism is provided between the motor 3000 and the lead screw nut matching mechanism of the rear wheel steering gear, so that the rotational motion of the motor 3000 is converted into the linear motion of the driving lead screw 3200 of the lead screw nut matching mechanism along the axial direction through the transmission of the transmission mechanism, and further the second control arm structure 4100 is driven to perform corresponding motion change, thereby realizing the steering of the rear wheel. Specifically, when the vehicle turns to, the vehicle transmits corresponding control signals to the motor 3000 according to the current whole vehicle state, so that the motor 3000 rotates and drives the driving lead screw 3200 of the lead screw nut matching mechanism to move axially through the first belt pulley 3300, the driving belt 3500 and the second belt pulley 3400, the driving nut 3100 and other multi-stage transmission modes, and then the driving lead screw 3200 sequentially drives the rear wheel to turn to a corresponding angle relative to the front wheel through the second control arm structure 4100 and the rear axle steering knuckle, so that the problems of insufficient steering or excessive steering can be improved, the turning flexibility, the stability of vehicle straight driving and the vehicle comfort are improved, the torque can be increased through the multi-stage transmission mode of the transmission mechanism and the lead screw nut matching mechanism, the requirement on the rated torque of the motor is reduced, the overall structure of the rear wheel steering system is rationalized, and the design difficulty is.

Based on the two embodiments described above, according to yet another aspect of the present disclosure, there is provided a vehicle including the rear wheel steering system as described above. Through the rear wheel steering gear and the rear wheel steering system, the rear wheels and the front wheels rotate in opposite phases when the speed is low or insufficient steering occurs, the turning radius is reduced, and the flexibility of the vehicle is improved. When the vehicle is in oversteer trend, particularly high-speed tail flicking trend, the rear wheels and the front wheels rotate in the same phase, the mass center slip angle of the vehicle is reduced, the steady-state overshoot of the yaw rate of the vehicle is reduced, the lane change stability is realized, the straight-line running stability of the vehicle is improved, and the comfort of the vehicle can be improved.

The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. A rear wheel steering device characterized by comprising: the steering mechanism comprises a motor (1000), a steering actuating mechanism and a multi-stage transmission mechanism, wherein the multi-stage transmission mechanism is in transmission connection with the motor (1000) and the steering actuating mechanism, the steering actuating mechanism (1100) comprises an actuating rod (1101) which is used for being connected with a rear axle steering knuckle so as to drive a rear wheel to steer, and the multi-stage transmission mechanism is in transmission connection with the actuating rod (1101) so as to convert the rotary motion of the motor (1000) into the linear motion of the actuating rod (1101) along the axial direction;

the multistage transmission mechanism comprises a first transmission mechanism in transmission connection with a motor output shaft (1001) of the motor (1000) and a transmission gear (1200) connected with the first transmission mechanism, and a rack (1102) used for being meshed with the transmission gear (1200) is arranged on the execution rod (1101);

the rear wheel steering gear comprises a gear-rack fit clearance adjusting mechanism (1400) for adjusting a meshing clearance between the transmission gear (1200) and the rack (1102);

the gear rack fit clearance adjusting mechanism (1400) comprises an adjusting plug (1401) and a pressing block (1402) mounted on the adjusting plug (1401), the adjusting plug (1401) can be mounted on an actuating rod housing (1501) in a position adjusting mode along a second adjusting direction, the actuating rod (1101) is mounted in the actuating rod housing (1501), a cutting surface (1103) extending along the axial direction of the actuating rod (1101) is formed on the portion, opposite to the rack (1102), of the actuating rod (1101) and used for being matched with the end portion of the pressing block (1402), and the actuating rod (1101) can move in the axial direction relative to the pressing block (1402) through the cutting surface (1103).

2. The rear wheel steering according to claim 1, wherein the first transmission mechanism includes a speed reduction mechanism connected to a motor output shaft (1001) of the motor (1000), and the transmission gear (1200) is provided on a power output shaft of the speed reduction mechanism.

3. The rear wheel steering gear according to claim 2, characterized in that the reduction mechanism is a worm gear reduction mechanism (1300) and comprises a worm (3) and a worm wheel (2) with the power output shaft in mesh with each other, the worm (3) being connected coaxially rotationally with the motor output shaft (1001).

4. The rear wheel steering gear according to claim 3, characterized in that the axis of rotation of the motor (1000) and the worm (3) is parallel to the central axis of the actuating lever (1101).

5. The rear wheel steering gear according to claim 4, characterized in that the worm (3) is a single-start worm and the lead angle of the worm (3) is smaller than the equivalent friction angle between the meshing wheel teeth of the worm wheel (2) and the worm (3).

6. The rear wheel steering gear according to claim 3, wherein the worm gear reduction mechanism (1300) includes a first housing (1) and a worm gear fit clearance adjustment mechanism provided in the first housing (1) for adjusting the worm (3) and the worm wheel (2).

7. The rear wheel steering gear according to claim 6, wherein the worm gear fit clearance adjusting mechanism comprises bearing adjusting structures supported at both ends of the worm (3) for driving the worm (3) to move in a first adjusting direction perpendicular to the axes of the worm wheel (2) and the worm (3) so that the worm (3) adjusts the meshing clearance with the worm wheel (2) in a state where the intersection angle with the axis of the worm wheel (2) is constant.

8. The rear wheel steering gear according to claim 7, characterized in that the bearing adjusting structure comprises a first adjusting component (4) arranged at the first end (31) and/or the second end (32) of the worm (3), the first adjusting component (4) comprises a first self-aligning bearing (41), an adjusting ring (42) arranged on the outer circumferential surface of the first self-aligning bearing (41) in a spherical fit manner, and a driving part arranged on the adjusting ring (42) and used for driving the first self-aligning bearing (41) to drive the worm (3) to move along the first adjusting direction in the adjusting ring (42) so as to adjust the meshing gap.

9. Rear wheel steering gear according to any of claims 3-8, characterized in that the motor output shaft (1001) end of the motor (1000) and the second end (32) of the worm (3) are connected by a coupling (9), which coupling (9) comprises a first coupling gear (91) which is form-fit with the second end (32) of the worm (3), a second coupling gear (92) which is form-fit with the end of the motor output shaft (1001) of the motor (1000), and a sleeve (93) for connecting the first coupling gear (91) and the second coupling gear (92).

10. The rear wheel steering according to claim 1, wherein the cutting surface (1103) is formed with a compact guide protrusion (1104) or a compact guide groove protruding or recessed in an axial direction of the actuating lever (1101), and the end of the compact (1402) is formed in a shape that fits the compact guide protrusion (1104) or the compact guide groove.

11. The rear wheel steering according to claim 1 or 10, wherein a pressing block limiting groove (1403) for limiting the pressing block (1402) is formed in the adjusting plug (1401), and a pressing spring (1404) is provided between a bottom end of the pressing block limiting groove (1403) and the pressing block (1402) so that the pressing block (1402) can be always kept pressed against the cutting surface (1103).

12. The rear wheel steering gear according to claim 11, wherein the adjusting plug (1401) is in sealing fit with the compression block (1402) through a first seal ring (1405), a thread is formed on an outer peripheral surface of the adjusting plug (1401) for screw-fitting with a rack and pinion fit clearance adjusting mechanism accommodating chamber of the actuator rod housing (1501), and a vent plug (1406) is provided on a top portion of the adjusting plug (1401).

13. The rear wheel steering according to claim 1, characterized in that the rear wheel steering comprises a displacement sensor for detecting an axial displacement of the actuator stem (1101).

14. The rear wheel steering gear according to claim 13, wherein the displacement sensor is a first linear displacement sensor (1600), the first linear displacement sensor (1600) includes a first induction magnet (1601) and a first sensor reading head (1602), the first induction magnet (1601) is mounted on the actuator stem (1101) in the actuator stem housing (1501) through a magnet mounting block (1603) and is capable of moving in the axial direction together with the actuator stem (1101), and the first sensor reading head (1602) is disposed on a portion of the actuator stem housing (1501) corresponding to the first induction magnet (1601) so as to be capable of acquiring the axial displacement of the actuator stem (1101) by detecting a change in the magnetic field of the first induction magnet (1601).

15. The rear wheel steering gear according to claim 13, wherein the displacement sensor is a second linear displacement sensor (2000), the second linear displacement sensor (2000) comprises a second linear displacement sensor housing (21), a transmission shaft (22), a rotary member, a magnetic induction chip (23) and a radially oriented multi-stage magnetic ring (24), the transmission shaft (22) is rotatably mounted in the second linear displacement sensor housing (21) with a first end of the transmission shaft exposed out of the second linear displacement sensor housing (21), the rotary member is mounted on the first end of the transmission shaft and cooperates with the actuating rod (1101) for converting the linear motion of the actuating rod (1101) into the rotational motion of the transmission shaft (22), the multi-stage magnetic ring (24) is sleeved on the transmission shaft (22), the magnetic induction chip (23) is mounted in the second linear displacement sensor housing (21) and cooperates with the multi-stage magnetic ring (24) ) The magnetic induction chips (23) are correspondingly arranged at intervals, so that when the transmission shaft (22) drives the multistage magnetic ring (24) to rotate within a circle range through the rotating piece, the rotation angle of the transmission shaft (22) can be obtained according to the magnetic field change generated by the rotation of the multistage magnetic ring (24).

16. The rear wheel steering gear according to claim 15, wherein the multi-stage magnetic ring (24) is fitted over the second end of the transmission shaft (22), and the magnetic induction chip (23) is disposed near the end of the multi-stage magnetic ring (24).

17. The rear wheel steering according to claim 16, wherein the multistage magnetic ring (24) is formed as a two-pole magnetic ring and is equally divided into an N-pole section and an S-pole section in a radial direction.

18. The rear wheel steering gear according to claim 17, wherein the second linear displacement sensor further comprises a torsion spring (28) for providing a pre-load to the rotary member in a state where the rotary member is engaged with the actuating lever (1101), the torsion spring (28) is fitted over an outer circumferential surface of the transmission shaft (22) near the rotary member, one end (281) of the torsion spring (28) is limited on the second linear displacement sensor housing (21), and the other end (282) is limited on the transmission shaft (22).

19. Rear wheel steering according to any of claims 17-18, characterized in that the rotating member is a second sensor gear (29), which second sensor gear (29) meshes with a gear rack (1102) provided on the actuating lever (1101).

20. The rear wheel steering device according to claim 1, comprising an angle sensor (1900) provided on a power output shaft (1901) of the transmission gear (1200) for detecting a rotation angle of the transmission gear (1200).

21. The rear wheel steering according to claim 1, wherein the steering actuator (1100) includes an actuator rod housing (1501) for mounting to the vehicle frame (4000), the actuator rod (1101) is axially movably mounted in the actuator rod housing (1501) with both ends exposed to both sides of the actuator rod housing (1501), respectively, and the steering actuator (1100) further includes a first control arm structure (1700) connected to both ends of the actuator rod (1101) for mounting to a rear axle knuckle.

22. The rear wheel steering gear according to claim 21, characterized in that both ends of the actuating rod (1101) are respectively provided with a first ball seat (1105), the first control arm structure (1700) comprises a first control arm (1701) and a second control arm (1702) which are mutually screw-connected, one end of the first control arm (1701) is provided with a first ball head (1703) which is fitted into the first ball seat (1105), the other end of the first control arm (1701) is screw-connected with one end of the second control arm (1702) for adjusting a rear wheel toe angle, and the other end of the second control arm (1702) is provided with a first joint (1704) for connecting with a rear axle steering knuckle.

23. The rear wheel steering gear according to claim 22, wherein each of the first ball seats (1105) is located on both sides of the actuating lever housing (1501) and has a preset clearance with both ends of the actuating lever housing (1501) in a rear wheel aligning state, respectively, so that each of the first ball seats (1105) can be stopped at the end of the actuating lever housing (1501) during the axial movement of the actuating lever (1101) for limiting the movement stroke of the actuating lever (1101).

24. Rear wheel steering according to claim 21, characterized in that the actuator lever (1101) is provided with a clevis at each end, and the first control arm arrangement comprises a third control arm (1800), which third control arm (1800) is provided with a bushing arrangement (1801) at one end for articulation with the clevis and at the other end with a first clevis joint (1802) or a first ball joint (1803) for connection with a rear axle knuckle.

25. A vehicle rear wheel steering system, characterized by comprising a rear wheel, a rear axle knuckle to which both ends of the actuating lever (1101) are connected, and a rear wheel steering according to any one of claims 1 to 24.

26. The vehicle rear wheel steering system according to claim 25, wherein the steering actuator (1100) includes an actuator rod housing (1501) for mounting to the vehicle frame (4000), the actuator rod (1101) is axially movably mounted in the actuator rod housing (1501) with both ends exposed to both sides of the actuator rod housing (1501), respectively, the steering actuator (1100) further includes a first control arm structure (1700) connected to both ends of the actuator rod (1101) for mounting to the rear axle knuckle, the first control arm structure (1700) serving as a sub-knuckle control arm of the rear axle knuckle.

27. A vehicle characterized in that the vehicle comprises a rear wheel steering system according to claim 25 or 26.