JP2006273295A - Steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect rotation angles of an input shaft and an output shaft without providing an angle detector for the input shaft and the output shaft. <P>SOLUTION: The steering device for the vehicle has the input shaft 1 connected to a steering means; the output shaft 2 interlocked/connected to the input shaft 1 by a differential mechanism A having a carrier 13 and connected to a steering mechanism; a first electric motor 3 having a rotor 31 and a first position detector 32 for detecting a position of the rotor 31 and rotating the carrier 13; and a second electric motor 4 having a rotor 41 and a second position detector 42 for detecting a position of the rotor 41 and applying required torque to the input shaft 1 according to torque applied to the output shaft 2. The rotation angles of the input shaft 1 and the output shaft 2 can be detected by the first and second position detectors 32, 42. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle steering apparatus in which an input shaft connected to a steering means and an output shaft connected to a steering mechanism are linked with a differential mechanism.

  A vehicle steering apparatus including a differential mechanism is disposed on the same axis as a sun gear provided on an input shaft connected to a steering wheel, a planetary gear meshing with the sun gear, and the sun gear. A carrier that is freely supported, an output shaft coupled to the center of the carrier and connected to the steering mechanism, an internal gear that is coaxially rotatable with the output shaft and meshes with the planetary gear, A differential electric motor having a drive gear meshed with an external tooth body provided on an outer peripheral portion of the gear, and is steered via the input shaft, the sun gear, the planetary gear, and the output shaft by operation of the steering wheel. The steering mechanism is operated, the internal gear is rotated by driving the electric motor, and the steering mechanism is accelerated through an output shaft connected to the carrier (for example, Patent Document 1). ).

  In addition, the vehicle steering apparatus disclosed in Patent Document 1 includes a first detector that detects the rotation angle of the input shaft, and a second detector that detects the rotation angle of the output shaft, and the first and second detectors. The drive circuit of the 1st and 2nd electric motor is controlled based on the detected value etc. which the detector detected, and it is comprised so that the rotation angle of the output shaft with respect to the rotation angle of an input shaft may be compensated.

Further, as a vehicle steering apparatus including a differential mechanism and a differential electric motor, a transmission gear is provided on an input shaft connected to the steering wheel, and an output shaft that is interlocked and connected to a drive gear that meshes with the transmission gear. There is also known a vehicle steering apparatus that includes a reaction force electric motor that applies a required torque to the input shaft according to the torque applied to the output shaft. Note that the reaction force electric motor is driven when the steering torque applied to the input shaft changes from the appropriate steering torque when the output shaft is rotated at a higher speed by the differential electric motor, and the torque applied to the output shaft. In response to this, a required torque is applied to the input shaft to correct the torque so that an appropriate steering torque can be obtained.
JP 2003-31486 A

  However, in the vehicle steering apparatus having the differential mechanism as in Patent Document 1, the first detector that detects the rotation angle of the input shaft and the second detector that detects the rotation angle of the output shaft. Therefore, there is a problem that the cost of the detector itself, the cost of the steering device for the vehicle is increased due to the work of assembling the detector, and that it is difficult to secure the installation space when mounted on the vehicle. there were.

  Further, even in a vehicle steering apparatus including a differential mechanism, a differential and a reaction force electric motor, a first detector for detecting a rotation angle of an input shaft and a rotation angle of an output shaft are detected. Since the second detector is required, there is a problem similar to that of Patent Document 1.

  The present invention has been made in view of such circumstances, and a main object of the present invention is for a vehicle capable of detecting the rotation angles of the input shaft and the output shaft without particularly providing an angle detector for the input shaft and the output shaft. The object is to provide a steering device. Another object of the present invention is to provide a vehicle steering apparatus that can detect torque with high accuracy by reducing the influence of rotational frictional resistance caused by a differential mechanism on torque applied to an input shaft.

  A vehicle steering apparatus according to a first aspect of the present invention includes an input shaft connected to steering means, an output shaft connected to the input shaft by a differential mechanism and connected to a steering mechanism, and a part of the differential mechanism. In a vehicle steering system including a first actuator and a second actuator that applies a required torque to the input shaft in response to a torque applied to the output shaft, the first and second actuators are rotor rotors. It has the 1st, 2nd electric motor which has the 1st, 2nd position detector which detects a rotation position, It is characterized by the above-mentioned.

  A vehicle steering apparatus according to a second aspect of the present invention has a first speed reduction mechanism between the first electric motor and the differential mechanism, and is between the second electric motor and the input shaft. A second reduction mechanism, the detection positions detected by the first and second position detectors, the reduction ratio of the first reduction mechanism, and the reduction ratio of the second reduction mechanism, And calculating means for calculating the rotation angles of the input shaft and the output shaft based on the above.

  A vehicle steering apparatus according to a third aspect of the present invention is a torque sensor that detects a torque applied to the input shaft around the input shaft and closer to the steering means than an interlocking connection portion of the input shaft with the differential mechanism. It is characterized by providing.

  In the first invention, the output shaft is rotated via the differential mechanism by the operation of the steering means connected to the input shaft. In this case, when the rotation angle of the output shaft is smaller than the rotation angle of the input shaft and the amount of operation of the steering mechanism is reduced during high-speed traveling, the first and second electric motors are not driven and controlled. The rotation angle is not detected. When the first electric motor is driven by the rotation angle of the input shaft, the torque applied to the input shaft, the vehicle speed, etc., the position of the rotor of the electric motor is detected by the first position detector, and the difference A part of the moving mechanism rotates, the output shaft rotates at an increased speed relative to the input shaft, the second electric motor is driven, and the position of the rotor of the electric motor is detected by the second position detector. And the input shaft rotates. The detection position detected by the second position detector of the second electric motor that rotates the input shaft is the rotation angle of the input shaft. Further, the detection position detected by the first position detector of the first electric motor that rotates the output shaft becomes the rotation angle of the output shaft, and the phase difference between the input shaft and the output shaft can be detected. As described above, since the phase difference between the input shaft and the output shaft can be detected by the position detectors of the first and second electric motors, it is not necessary to provide an angle detector for the input shaft and the output shaft. The structure can be simplified and the cost can be reduced as compared with the case where a position detector is required on the input shaft side and the output shaft side.

  In the second invention, the rotational speed of the first electric motor is decelerated by the first speed reduction mechanism and transmitted from the differential mechanism to the output shaft, and the rotational speed of the second electric motor. Is decelerated by the second reduction mechanism and transmitted to the input shaft, so that the resolution of the first and second position detectors can be made with high accuracy, and the phase difference between the input shaft and the output shaft can be made with high accuracy. Can be detected.

  In the third aspect of the invention, the torque sensor for detecting the torque applied to the input shaft is provided on the side opposite to the output shaft from the interlocking connection portion with the differential mechanism of the input shaft. The influence of the resistance can be reduced to detect the torque with high accuracy, and the control accuracy when the first and second electric motors are controlled based on the detected torque or the like can be increased.

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof.
Embodiment 1
1 is a cross-sectional view showing a configuration of a first embodiment of a vehicle steering apparatus according to the present invention, FIG. 2 is an enlarged cross-sectional view of a main part, and FIG. 3 is a schematic perspective view of a carrier part.

  This vehicle steering device has an input shaft 1 whose one end is connected to a steering wheel as a steering means, one end of the input shaft 1 is linked to the other end of the input shaft 1 by a differential mechanism A, and the other end is For example, an output shaft 2 connected to a rack and pinion type steering mechanism, a first electric motor 3 as a first actuator for rotating the output shaft 2 at an increased speed with respect to the input shaft 1, and torque applied to the output shaft 2 For the reaction force that applies the required torque to the input shaft 1 according to the above, in other words, when the torque applied to the input shaft 1 changes from the appropriate torque, the reaction force torque in the same direction as the torque applied to the input shaft 1 is applied to the input shaft. A second electric motor 4 serving as a second actuator to be added to 1 and a control unit 5 for controlling the drive circuits 3a and 4a of the first and second electric motors 3 and 4 are provided.

  The input shaft 1 and the output shaft 2 are spaced apart on the same axis. The input shaft 1 has a cylindrical first shaft 1a whose one end is connected to the steering wheel, and one end of the input shaft 1 is rotatably fitted to the other end of the first shaft 1a. A second shaft body 1b provided with one sun gear, and a third shaft that is fitted and fixed to one end of the second shaft body 1b, and a second large gear 6 is integrally provided on the outer periphery thereof. The body 1c has a torsion bar 1d that interlocks the first shaft body 1a and the second shaft body 1b and is twisted by the operating force of the steering wheel, and the first shaft body 1a and the third shaft body 1c are A bearing 7 is rotatably supported by the housing 7. The output shaft 2 is rotatably supported on the housing 7 by a bearing.

  On the input shaft 1 on the opposite side of the output shaft 2 from the outer periphery of the input shaft 1 and the interlocking connection portion (the interlocking connection portion with the first sun gear 9 described later) of the input shaft 1 with the differential mechanism A. A torque sensor 8 that detects the applied torque is provided.

  The torque sensor 8 is disposed around the first shaft body 1a and the third shaft body 1c, and has two magnetic rings 8a and 8b each having a rectangular tooth portion formed circumferentially on the end surface thereof, and the magnetic ring. When the magnetic rings 8a and 8b are rotated relative to the torsion of the torsion bar 1d, the opposing areas of the tooth portions change. The torque is detected by changing the impedance of the coil 8c.

  The differential mechanism A includes a first sun gear 9 provided integrally with the other end of the input shaft 1, a second sun gear 10 provided integrally with one end of the output shaft 2, A plurality of first planetary gears 11 meshing with the sun gear 9; a second planetary gear 12 rotating coaxially with the first planetary gear 11 and meshing with the second sun gear 10; And a carrier 13 that supports the first and second planetary gears 11 and 12.

  The first and second planetary gears 11 and 12 are integrally formed on the same axis, and a shaft body 11a is fitted into a through-hole penetrating the center portion, and both end portions of the shaft body 11a are connected to a needle. It is rotatably supported by the carrier 13 via a roller bearing.

The first and second planetary gears 11 and 12 and the first and second sun gears 9 and 10 are spur gears. When the rotation of the input shaft 1 is transmitted to the output shaft 2, the output shaft 2 The torque ratio between the torque applied to the input shaft 1 and the torque applied to the input shaft 1 is set to an appropriate torque ratio of 1: 0.7 to 0.9. This torque ratio is
(Z1 ÷ Z2) × (Z3 ÷ Z4)
It is calculated by the following formula. Where Z1 is the number of teeth of the first sun gear 9, Z2 is the number of teeth of the first planetary gear 11, Z3 is the number of teeth of the second planetary gear 12, and Z4 is the number of teeth of the second sun gear 10. is there. The torque ratio of 1: 0.7 to 0.9 is the rotational speed of the first and second electric motors 3 and 4, the rotational speed of the carrier 13, and the consumption of the first and second electric motors 3 and 4. It is decided based on electric power.

  The carrier 13 is rotated to the outer peripheral portion of the output shaft 2 through the needle roller bearing and the annular first plate portion 13a that is fitted and supported on the outer peripheral portion of the input shaft 1 through the needle roller bearing. Of the annular second plate portion 13b that is freely fitted and supported, connecting members 13d and 13d that connect the first plate portion 13a and a plurality of outer peripheral portions of the second plate portion 13b, and the first plate portion 13a. It has a cylindrical portion 13c which is connected to the outer peripheral portion and arranged outside the first planetary gear 11. An annular first large gear 14 made of a spur gear is integrally provided on the outer peripheral portion of the first plate portion 13a on one side in the central axis direction, and on the other side in the central axis direction. Needle roller bearings 15 and 16 are fitted on the outer peripheral portions of the cylindrical portion 13c and the second plate portion 13b, and the carrier 13 can be cantilevered in the housing 7 by the needle roller bearings 15 and 16. It is supported by. The connecting members 13d and 13d are connected by screws 13e and 13e passing through the connecting members 13d and 13d and the first plate portion 13a and the second plate portion 13b, respectively.

  The first electric motor 3 includes a rotor 31 disposed in parallel with the input shaft 1 and the output shaft 2, and a first position detector 32 for detecting the position of the rotor 31, and the first position The driving circuit 3 a is connected to the control unit 5 and is composed of a brushless DC motor that rectifies electronically by a detector 32 and a semiconductor switch. A drive shaft 33 is coaxially coupled to the rotor 31, and a first small gear 17 provided in the middle of the drive shaft 33 meshes with the first large gear 14.

  The second electric motor 4 includes a rotor 41 arranged in parallel with the input shaft 1 and the output shaft 2, and a second position detector 42 that detects the position of the rotor 41. The driving circuit 4 a is connected to the control unit 5, and includes a brushless DC motor that rectifies electronically by a detector 42 and a semiconductor switch. The rotor 41 is coaxially connected with a drive shaft 43, and a second small gear 18 provided in the middle of the drive shaft 43 is a second large gear provided integrally in the middle of the input shaft 1. 6 meshes.

  The first large gear 14 and the first small gear 17 constitute a first reduction mechanism B, and the second large gear 6 and the second small gear 18 constitute a second reduction mechanism C. Yes.

  The first position detector 32 is fixed to the outer periphery of the drive shaft 33, is disposed around the detection rotor 32 a that rotates integrally with the rotor 31, and is held by the motor case 34. The detection stator 32b is configured to detect a change in the rotation position of the detection rotor 32a as a change in impedance by the detection stator 32b and detect the rotation position of the rotor 31.

  The second position detector 42 is fixed to the outer periphery of the drive shaft 43, is disposed around the detection rotor 42 a that rotates integrally with the rotor 41, and is held by the motor case 44. The detection stator 42b is configured to detect a change in the rotation position of the detection rotor 42a as a change in impedance by the detection stator 42b and detect the rotation position of the rotor 41.

  The detection stators 32b and 42b of the first and second position detectors 32 and 42 are connected to the control unit 5, and the detection positions detected by the first and second position detectors 32 and 42, and the first The control unit 5 is provided with calculation means for calculating the rotation angles of the input shaft 1 and the output shaft 2 based on the reduction ratio of the reduction mechanism B and the reduction ratio of the second reduction mechanism C.

  The control unit 5 uses a microprocessor, the torque sensor 8 and the first and second position detectors 32 and 42 are connected to the input unit of the control unit 5, and the first and second position detectors are connected to the output unit. The drive circuits 3a and 4a of the two electric motors 3 and 4 are connected.

Since the input shaft 1 and the output shaft 2 are interlocked and connected by the differential mechanism A, the rotation angle θ1 of the input shaft 1 and the rotation angle θ2 of the output shaft 2 are
θ1 = θ5 = θ4 × C '………………… (1)
θ6 = θ3 × B '………………………… (2)
θ2 = (Y × θ5) + {(1-Y) × θ6} (3)
It is calculated by the following formula. Where θ3 is the detection position (detection angle) detected by the first position detector 32, θ4 is the detection position (detection angle) detected by the second position detector 42, and θ5 is the rotation of the first sun gear 9. The angle, θ6 is the rotation angle of the carrier 13, B ′ is the reduction ratio of the first reduction mechanism B, C ′ is the reduction ratio of the second reduction mechanism C, and Y is applied to the carrier 13 via the first reduction mechanism B. This is the torque ratio between the torque and the torque applied to the first sun gear 9 via the second reduction mechanism C, and this torque ratio Y is 1: 0.7 to 0.9 as described above.

  The housing 7 includes a small-diameter cylindrical portion 71a in which the output shaft 2 is accommodated and supported, a medium-diameter cylindrical portion 71b in which the carrier 13 is accommodated and supported, and a large-diameter cylindrical portion in which the first and second small gears 17 and 18 are accommodated and supported. A first cylinder 71 having 71c, a second cylinder 72 in which the input shaft 1 and the torque sensor 8 are accommodated and supported, a third cylinder 73 in which one end of the second cylinder 72 is accommodated, An annular connecting plate 74 that connects the first cylinder 71 and the third cylinder 73 is provided.

  The steering mechanism is configured as a rack and pinion type having a pinion and a rack shaft meshing with the pinion and capable of moving in the axial length direction, and an output shaft 2 The pinion is linked to each other via a universal joint and an intermediate shaft, and steered wheels are supported at both ends of the steered shaft.

  In the vehicle steering apparatus configured as described above, the first sun gear 9, the first and second planetary gears 11, 12, and the second sun gear 10 are obtained when the steering wheel rotates the input shaft 1. After that, the output shaft 2 rotates at the same speed as the input shaft 1. Further, when the first electric motor 3 is driven by a command signal output from the control unit 5 to the drive circuit 3a, the carrier 13 rotates through the first reduction mechanism B, and the first and second planets. The output shaft 2 rotates at an increased speed through the gears 11 and 12 and the second sun gear 10. When the steering torque applied to the input shaft 1 changes from the appropriate torque due to the accelerated rotation of the output shaft 2, a second command signal is output from the control unit 5 to the drive circuit 4 a according to the torque applied to the output shaft 2. The electric motor 4 is driven, for example, a reaction torque in the same direction as the rotation direction of the input shaft 1 is applied to the input shaft 1 through the second reduction mechanism C, and the torque ratio between the output shaft 2 and the input shaft 1 is increased. Can be maintained at a predetermined value of 1: 0.7 to 0.9, and the steering torque applied to the input shaft 1 can be maintained at an appropriate value.

  When the first and second electric motors 3 and 4 are driven, the rotational position of the rotor 31 is detected by the first position detector 32, and the rotational position of the rotor 41 is detected by the second position detector 42. Detected. The detection values detected by the first and second position detectors 32 and 42 are input to the control unit 5, and the calculation unit of the control unit 5 calculates the rotation angle of the input shaft 1 and the rotation angle of the output shaft 2. The phase difference between the input shaft 1 and the output shaft 2 can be detected, and the rotation angle of the output shaft 2 relative to the input shaft 1 can be corrected by this phase difference.

  When the torsion bar 1d is twisted by rotating the input shaft 1 by the steering wheel and torque is applied to the input shaft 1, this torque is detected by the torque sensor 8, and the detected torque is input to the control unit 5 for control. A command signal is output from the unit 5 to the drive circuits 3a and 4a, and the first and second electric motors 3 and 4 are driven and controlled in accordance with the torque applied to the input shaft 1.

Embodiment 2
FIG. 4 is a schematic diagram showing the configuration of the second embodiment of the vehicle steering apparatus according to the present invention. This vehicle steering apparatus includes an input shaft 1 and an output shaft 2 that are rotatably arranged on the same axis, a sun gear 20 that is rotatably fitted on the output shaft 2, and an outer periphery of the sun gear 20. And the planetary gear 22 that meshes with the sun gear 20 and the internal gear 21, and the planetary gear 22 is supported and output. A differential mechanism D having a carrier 23 in which the shaft 2 is coaxially linked, a first electric motor 24 arranged around the output shaft 2 and rotating the sun gear 20, and the input shaft 1 A second electric motor 25 that is driven when the steering torque changes from the appropriate steering torque and applies a required torque to the input shaft 1 according to the torque applied to the output shaft 2 or the like is provided.

  In the second embodiment, the internal gear 21 has a bottomed cylindrical shape having teeth on the inner periphery, and the input shaft 1 is coupled to the center of the bottom. The sun gear 20 is formed integrally with a cylindrical rotor 24a, a permanent magnet 24b is provided on the outer periphery of the rotor 24a, and a stator 24c is provided around the outer periphery of the permanent magnet 24b. . The carrier 23 has a disk shape, and planetary gears 22 and 22 are equally distributed and supported at two positions deviated from the center of rotation.

The sun gear 20, the internal gear 21, and the planetary gear 22 of the differential mechanism D are spur gears. By setting the number of teeth Z5 of the sun gear 20 to 11 and the number of teeth Z6 of the internal gear 21 to 45, the input shaft When transmitting the rotation of 1 to the output shaft 2, the torque ratio between the torque applied to the output shaft 2 and the torque applied to the input shaft 1 is Z6 / (Z6 + Z5)
It is calculated by the following formula.
This torque ratio is set to an appropriate torque ratio of 1: 0.7 to 0.9 as in the first embodiment.

  The first electric motor 24 includes a first position detector 32 that detects the position of the rotor 24a, and the second electric motor 25 determines the position of the rotor 25a and the rotor 25a. It has the 2nd position detector 42 to detect.

In the second embodiment, by rotating the input shaft 1, the output shaft 2 rotates at a reduced speed via the internal gear 21, the planetary gear 22 and the carrier 23. Further, when the first electric motor 24 is driven by a command signal output from the control unit 5 to the drive circuit, the output shaft 2 rotates at a higher speed through the sun gear 20, the planetary gear 22 and the carrier 23. When the steering torque applied to the input shaft 1 changes from the appropriate steering torque due to the increased rotation of the output shaft 2, a second command signal is output from the control unit 5 to the drive circuit according to the torque applied to the output shaft 2. The electric motor 25 is driven, for example, a reaction torque in the same direction as the rotation direction of the input shaft 1 is applied to the input shaft 1, and the torque ratio is maintained at a predetermined value of 1: 0.7 to 0.9. The steering torque applied to the input shaft 1 can be maintained at an appropriate value.
Since other configurations and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals, and detailed description thereof and description of operations and effects are omitted.

  In the above-described embodiment, the first and second position detectors 32 and 42 are provided with a resolver. However, a rotary encoder or a hall element may be provided.

It is sectional drawing which shows the structure of Embodiment 1 of the steering apparatus for vehicles which concerns on this invention. It is an expanded sectional view of the important section showing composition of Embodiment 1 of a steering device for vehicles concerning the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective view of a carrier portion showing the configuration of a first embodiment of a vehicle steering apparatus according to the present invention. It is a schematic diagram which shows the structure of Embodiment 2 of the steering apparatus for vehicles which concerns on this invention.

Explanation of symbols

1 input shaft 2 output shaft A differential mechanism 3 first electric motor (first actuator)
31 Rotator 32 First Position Detector 4 Second Electric Motor (Second Actuator)
41 Rotator 42 Second Position Detector B First Reduction Mechanism C Second Reduction Mechanism 5 Control Unit (Calculation Unit)
8 Torque sensor

Claims (3)

  An input shaft connected to the steering means, an output shaft connected to the input shaft by a differential mechanism and connected to the steering mechanism, a first actuator for rotating a part of the differential mechanism, and the output shaft And a second actuator for applying a required torque to the input shaft according to the torque, wherein the first and second actuators detect the rotational position of the rotor. A vehicle steering apparatus comprising first and second electric motors having position detectors.   A first reduction mechanism is provided between the first electric motor and the differential mechanism, and a second reduction mechanism is provided between the second electric motor and the input shaft. The rotation of the input shaft and the output shaft based on the detection positions detected by the first and second position detectors and the reduction ratio of the first reduction mechanism and the reduction ratio of the second reduction mechanism. The vehicle steering apparatus according to claim 1, further comprising calculation means for calculating an angle.   3. The vehicle according to claim 1, further comprising a torque sensor that detects torque applied to the input shaft around the input shaft and closer to the steering means than an interlocking connection portion of the input shaft with the differential mechanism. Steering device.

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