JP5221891B2 - Vehicle steering assist device - Google Patents

Description

  The present invention relates to a vehicle steering assist device that assists steering in a vehicle.

As a steering assist device for a vehicle that supports steering of a vehicle, a device that reduces a steering rotational force required to rotate a steering wheel during steering has been proposed, such as a so-called steering power assist system. Furthermore, a technique for changing a steering angle ratio, which is a ratio of a steering angle of a steered wheel with respect to a steering wheel steering angle, in accordance with the vehicle speed has been proposed (for example, see Patent Document 1).
JP 2000-16317 A

  However, the conventional vehicle steering assist device is functionally redundant as a result of various measures taken from the viewpoint of fail-safe, and is a complicated and expensive device.

  In view of the above problems, an object of the present invention is to provide an inexpensive vehicle steering assistance device with a simple structure while achieving fail-safe.

The present invention provides a steering assist device for a vehicle having an input shaft to which a steering rotational force of a steering wheel is transmitted, and an output shaft that transmits a steering force according to the steering rotational force to a steered wheel. a vehicle speed, a linear slide force generating means for generating a linear slide force according to at least one of the yaw rate, and a slider for converting said linear sliding force in addition possible assistance torque to the steering force, the linear The sliding force generating means includes a motor, a worm wheel that rotates at a reduced speed through a worm gear by the rotation of the motor, and the input by the rotation of the worm wheel while rotatably supporting the slider around the rotation shaft of the input shaft. A slider holder that moves in the direction of the rotation axis of the shaft or the output shaft, and the slider and the front Input shaft impossible relative rotation around the rotational axis of the input shaft can be relatively displaced in the axial direction of the input shaft, the slider, the steering rotational force to the output shaft receives from the input shaft Transmitting the steering force and moving the slider holder to cause the linear slide force to act in the direction of the respective rotation shafts of the input shaft and the output shaft, and to each of the input shaft and the output shaft. If the input shaft and the output shaft are relatively rotated when moved relative to the direction of the rotation axis, the motor is stopped and the slider is stopped along with the input shaft. The output shaft does not rotate relatively, and at the time of failure, the input shaft by the slider and the output shaft And wherein the stopping the relative movement of the respective force shaft.

  According to the vehicle steering assist device of the present invention, first, the slider can receive the steering rotational force applied to the steering wheel from the input shaft and transmit it to the output shaft. The output shaft can be rotated by the transmitted steering rotational force to steer the steered wheels.

  The slider can apply a linear slide force corresponding to at least one of a steering angle, a vehicle speed, and a yaw rate in the direction of the rotation shaft of each of the input shaft and the output shaft. By this action, the slider moves relative to the input shaft and the output shaft in the direction of the rotation axis. By this movement, at least one of the input shaft and the output shaft rotates by obtaining a rotational force, and the input shaft and the output shaft rotate relatively. This rotation is independent of the rotation due to the steering torque transmitted from the input shaft to the output shaft via the slider. For this reason, these two types of rotations can be superimposed on the output shaft. As a result, the steering angle ratio can be changed. Further, the present invention can be completed with a simple and inexpensive structure in which a linear slide force generating means and a slider are added to the input shaft and the output shaft.

  In addition, when the vehicle steering assist device fails, the input shaft and the output shaft due to the movement of the slider are stopped by stopping the relative movement of the slider with respect to the input shaft and the output shaft. Since only the relative rotation of the vehicle can be easily stopped, the vehicle steering assist device of the present invention has a fail-safe configuration.

  When the slider moves relative to each of the input shaft and the output shaft in the direction of the rotation axis, the slider moves around the rotation axis relative to at least one of the input shaft and the output shaft. It is preferable to rotate it. According to this, the input shaft and the output shaft rotate relatively, and the rotation angle of the input shaft can be made different from the rotation angle of the output shaft.

  According to the present invention, it is possible to provide an inexpensive vehicle steering assistance device with a simple structure while achieving fail-safe.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a configuration diagram of a steering system 1 having a vehicle steering assist device according to a first embodiment of the present invention. The vehicle steering assist device includes a vehicle steering assist device body 2 and a control means 3.

  The steering wheel 11 is integrally coupled to the steering shaft 12. The steering shaft 12 is connected to the input shaft 9 by a universal joint 19 via a connecting shaft 13. A steering rotational force (steering torque) Fi of the steering wheel 11 is transmitted to the input shaft 9.

  The vehicle steering assist device body 2 is configured to include a lower portion of the input shaft 9 and an upper portion of the output shaft 10. A pinion 14 is attached to the lower portion of the output shaft 10. The pinion 14 meshes with the rack 15, and the rack 15 and the pinion 14 constitute a rack and pinion mechanism. The rack and pinion mechanism converts the rotational movement of the pinion 14 into the linear movement of the rack 15. Thus, the vehicle steering assist device body 2 is installed between the steering wheel 11 and the rack and pinion mechanism that steers the steering wheel 18 and is input to the steering shaft 12 connected to the steering wheel 11. The shaft 9 can be connected and the pinion 14 can be connected to the output shaft 10.

  Steering wheels 18 are connected to both ends of the rack 15 via tie rods 16 and knuckle arms 17 so that the linear motion of the rack 15 is converted into the steering motion of the steering wheels 18. Yes. The output shaft 10 transmits a steering force Fo corresponding to the steering torque Fi to the steered wheels 18.

  The steering power assist system is mounted between a steering power assist system main body 4 attached to a rack 15 and assisting the driver's steering, and between the steering wheel 11 and the vehicle steering assist device main body 2, for example, an input shaft 9. And a torque sensor 5 arranged at the same position. According to this arrangement, the fluctuation amount of the steering torque Fi at the steering wheel 11 when the steering angle ratio changes can be automatically compensated by the power steering assist amount of the steering power assist system.

  The torque sensor 5 detects the steering torque Fi input from the steering wheel 11 by the driver. The steering power assist system main body 4 outputs power assistance corresponding to the steering torque Fi via the rack 15 based on the signal from the control means 3 that has received the signal corresponding to the detected steering torque Fi.

  The control unit 3 receives a signal corresponding to the steering wheel angle from the steering wheel angle measuring unit 6, receives a signal corresponding to the vehicle speed from the vehicle speed meter 7, and receives a signal corresponding to the yaw rate from the yaw rate measuring unit 8. The control means 3 outputs a driving current D corresponding to the steering wheel angle, the vehicle speed, and the yaw rate, drives the vehicle steering assist device main body 2, and changes the steering angle ratio. Further, the control means 3 receives a signal corresponding to the steering torque Fi from the torque sensor 5 and performs power assistance by the steering power assist system main body 4.

  FIG. 2 is an exploded perspective view of the vehicle steering assist device body 2 of the vehicle steering assist device. FIG. 3 is a cross-sectional view of the vehicle steering assist device body 2 of the vehicle steering assist device, and shows a case where the input shaft 9 rotates. 4 is a cross-sectional view in the AA direction of FIG. 3, and FIG. 5 is a cross-sectional view in the BB direction of FIG.

  As shown in FIG. 2, the vehicle steering assist device body 2 includes a slider 21 that houses the lower end side of the input shaft 9 and the upper end side of the output shaft 10, a slider holder 24 that houses the slider 21, and the slider 21 and slider. The retainer 23 is interposed between the holders 24 and a worm wheel 25 to which the slider holder 24 is screwed.

  On the outer periphery of the lower end side of the input shaft 9, there are two input side grooves 9a that run vertically and have a width and depth that accommodate approximately half of the input side ball 9b, and are opposed to each other with the rotary shaft 2a of the input shaft 9 therebetween. Is provided. Each input side groove 9 a is a groove whose lower part reaches the lower end side of the input shaft 9 and is opened.

  On the outer periphery on the upper end side of the output shaft 10, a single spiral output-side groove 10a having a width and a depth for accommodating approximately half of the output-side ball 10b is provided. The output side groove 10a is a groove whose upper part reaches the upper end side of the output shaft 10 and is opened. The lower end surface of the input shaft 9 and the upper end surface of the output shaft 10 face each other when accommodated in the slider 21. The lower end surface and the upper end surface are close to or in contact with the input shaft 9 and the output shaft 10. When arranged, the input shaft 9 and the output shaft 10 are shaped so as not to interfere with the relative rotation.

  The upper side of the slider 21 is a portion that accommodates the lower end side of the input shaft 9, and two hemispherical input side depressions 9 c that accommodate approximately half of the input side ball 9 b are provided on the inner peripheral surface thereof. It is provided in the position which opposes on both sides of 2a. Since the input side groove 9a is formed on the lower end side of the input shaft 9, the lower end side of the input shaft 9 can be accommodated on the upper side of the slider 21 in a state where the input side ball 9b is stored in the input side recess 9c. . When accommodated in this manner, the input shaft 9 and the slider 21 are relatively unrotatable and relatively movable along the input-side groove 9a in the direction of the rotation axis 2a (vertical direction).

  On the other hand, the lower side of the slider 21 is a portion that accommodates the lower end side of the output shaft 10, and two hemispherical output side depressions 10 c that accommodate approximately half of the output side ball 10 b are disposed on the inner peripheral surface of the slider 21. Is provided by shifting a predetermined amount in the vertical direction from the position facing the rotation shaft 2a (provided at a position allowing for the pitch of the spiral output side groove 10a). Since the spiral output side groove 10a is formed on the upper end side of the output shaft 10 as described above, the lower end side of the output shaft 10 is placed under the slider 21 in a state where the output side ball 10b is placed in the output side recess 10c. Can be accommodated on the side. When accommodated in this manner, the output shaft 10 and the slider 21 can be relatively rotated along the output-side groove 10a and can be relatively moved in the direction of the rotation axis 2a (vertical direction).

  The slider 21 has a slider groove 21a which is an annular groove having a width and a depth for accommodating approximately half of the slider ball 22 on the outer peripheral surface of a substantially central portion in the height direction, and is formed around the outer peripheral surface. . The slider holder 24 is formed with a slider groove 24a, which is an annular groove having a width and a depth for accommodating approximately half of the slider ball 22 on the inner peripheral surface of the substantially central portion in the height direction, and making a round around the inner peripheral surface. Has been. The slider holder 24 accommodates the slider 21 by interposing a retainer 23 holding a plurality of slider balls 22 between the slider groove 21a and the slider groove 24a. For this reason, the slider 21 and the slider holder 24 can be relatively rotated and cannot be relatively moved in the direction of the rotating shaft 2a. Note that, for example, means such as a cooling swab is applied to the assembly in which the retainer 23 holding a plurality of slider balls 22 is interposed between the slider 21 and the slider holder 24.

As shown in FIG. 3, the input shaft 9 and the output shaft 10 are arranged so that their end faces face each other so that the rotation shafts 2a overlap and coincide with each other. This reduces the blurring of the vehicle steering assist device main body 2 accompanying the rotation of the vehicle.
The slider 21 has a cylindrical shape, and a lower end portion of the input shaft 9 and an upper end portion of the output shaft 10 are inserted therein.

  The ball 9b is accommodated approximately half in a recess 9c formed on the inner peripheral surface on the upper side of the slider 21 (opposite surface facing the lower end side of the input shaft 9), while the outer peripheral surface on the lower end side of the input shaft 9 is Since the vertical groove 9a is formed, as described above, the input shaft 9 and the slider 21 cannot be rotated relative to each other and can move in the direction of the axis 2a (vertical direction) along the groove 9a.

  For this reason, the slider 21 and the input shaft 9 slide with respect to each other with the input side ball 9b interposed therebetween. Therefore, when sliding in the direction (vertical direction) along the input side groove 9a, a frictional force is not easily generated. A large frictional force can be generated by trying to slide in a direction different from the direction along the side groove 9a, for example, in the vertical direction (around the axis) of the input side groove 9a. The steering torque Fi and the linear slide force Fadd (see FIG. 6) can be transmitted efficiently, and a so-called key having a small frictional resistance can be formed.

  In addition, the ball 10b is accommodated approximately in a recess 10c formed on the lower inner peripheral surface of the slider 21 (opposite surface facing the upper end side of the output shaft 10), while the outer periphery on the lower end side of the output shaft 10 is included. Since the spiral groove 10a is formed on the surface, as described above, the output shaft 10 and the slider 21 can be relatively rotated along the groove 10a and can be moved in the direction of the axis 2a (vertical direction). Become.

  For this reason, the slider 21 and the output shaft 10 slide with respect to each other with the output side ball 10b interposed therebetween, so that a frictional force is hardly generated in the direction along the output side groove 10a, and the direction along the output side groove 10a is Large frictional forces can be generated in different directions. The steering torque Fi and the linear slide force Fadd (see FIG. 6) can be transmitted efficiently, and a so-called key having a small frictional resistance can be formed.

  According to these, as shown in FIG. 3, the steering torque Fi applied to the input shaft 9 can be transmitted to the slider 21 via the input side ball 9b, and the rotational force Fsr of the slider 21 is It becomes equal to the steering torque Fi (Fsr = Fi). When the input shaft 9 rotates by the handle angle θi, the slider 21 also rotates by the handle angle θi, and the rotation angle θsr of the slider 21 becomes equal to the handle angle θi (θsr = θi). Similarly, the steering torque Fi applied to the slider 21 can be transmitted to the output shaft 10 via the output side ball 10b, and the turning force Fo of the output shaft 10 becomes equal to the steering torque Fi (Fo = Fsr = Fi). When the slider 21 rotates by the rotation angle θsr (= θi), the output shaft 10 also rotates by the turning angle θo (= θi), and the turning angle θo of the output shaft 10 becomes equal to the steering wheel angle θi (θo). = Θsr = θi). That is, the handle angle θi can be transmitted from the input shaft 9 to the output shaft 10 as it is.

As described above, the slider holder 24 accommodates the slider 21 with the retainer 23 holding a plurality of slider balls 22 interposed between the slider groove 21a and the slider groove 24a. For this reason, the slider 21 and the slider holder 24 can rotate relative to each other and cannot move in the axial direction.
The worm wheel 25 is rotatably disposed inside the housing 27. The worm wheel 25 meshes with the worm gear 26 so that the rotational force from the worm gear 26 is transmitted.
24 The slider holder 24 moves up and down by the rotation of the worm wheel 25.

  4 is a cross-sectional view taken along the line AA in FIG. 3, and as shown in FIG. 4, the input side shaft 9 is inserted into the slider 21. The slider 21 is inserted in the slider holder 24. The slider holder 24 is housed in the housing 27.

  In the cross section shown in FIG. 4, the slider holder 24 is not relatively rotatable with respect to the casing 27 and can move up and down along the axial direction (movement from the front of the paper to the depth direction). Further, the slider 21 can rotate around the axis with respect to the slider holder 24. Further, since the slider 21 is inserted into the slider holder 24 with the retainer 23 interposed, the housing 27 is subject to forward / backward (up / down) movement along the axial direction and rotational movement around the axis. Is possible. Further, the input shaft 9 can move forward and backward (up and down) with respect to the slider 21, but cannot relatively rotate.

  5 is a cross-sectional view taken along the line B-B in FIG. 3, and as shown in FIG. 5, the output-side shaft 10 is inserted into the slider 21. The slider 21 is inserted into the slider holder 24 with a retainer 23 interposed. Further, the slider holder 24 is inserted into the worm wheel 25, screwed, and inserted. The worm wheel 25 is screwed into the worm gear 26. The worm wheel 25 and the worm gear 26 are housed in a housing 27. A motor 28 is fixed to the casing 27. The motor 28 can be rotated by the drive current D to rotate the worm gear 26.

  The vehicle steering assist device can be considered to have linear slide force generation means for generating a linear slide force Fadd according to the steering torque Fi. The linear slide force generating means includes the control means 3 of FIG. 1 and the motor 28 shown in FIG. 5 that rotates according to the steering torque Fi, and the worm gear 26 that is rotated by the motor 28 (see FIGS. 3 and 5). ).

  Further, the linear sliding force generating means includes a worm wheel 25, a slide key groove 27a (see FIG. 3), a slider holder 24, and a slider ball 22 with a retainer 23. The worm wheel 25 has external teeth meshing with the worm gear 26 and rotates at a reduced speed, and the internal teeth are internal screw teeth 25a (see FIG. 2). The slide key groove 27a (see FIG. 3) is formed in the casing 27 in parallel with the rotation shaft 2a. The slider holder 24 has a cylindrical shape, has external screw teeth 24c that are screwed with the internal screw teeth 25a of the worm wheel 25, and is provided in the slide key groove 27a to prevent rotation of the slide key 24b (FIG. 2). And a slider holder 24 that moves in the direction of the rotating shaft 2 a by the rotation of the worm wheel 25. The slider ball 22 has a slider groove 21a formed on the outer peripheral surface of the slider 21 in a direction perpendicular to the direction parallel to the rotating shaft 2a, and a slider groove 24a formed on the inner peripheral surface of the slider holder 24 in the same direction. And is fitted. As a result, the slider holder 24 can support the slider 21 so as to be rotatable about the rotation shaft 2a. Then, by rotating the motor 28 (see FIG. 5), as shown in FIG. 6, the slider holder 24 can be moved in the direction of the rotating shaft 2a by the actual slide amount Sadd to generate the linear slide force Fadd. . As the slider holder 24 moves in the direction of the rotating shaft 2a, the slider 21 also moves in the direction of the rotating shaft 2a by the actual slide amount Sadd, and the slider 21 moves relative to the input shaft 9 and the output shaft 10, respectively. The actual slide amount Sadd moves relative to the direction of the rotating shaft 2a.

  When the linear slider 21 moves relative to the input shaft 9 and the output shaft 10 in the direction of the rotation axis 2 a by the actual slide amount Sadd, the input shaft 9 rotates relative to the output shaft 10. The input side angle that is rotated relatively to the direction parallel to the rotation axis 2a in the direction of the input side groove 9a is different from the output side angle that is parallel to the rotation axis 2a in the direction of the output side groove 10a. Because. The rotation angle of the input shaft 9 and the rotation angle of the output shaft 10 can be made different from each other with respect to the equal actual slide amount Sadd of the slider 21 with respect to the input shaft 9 and the output shaft 10. A rotational angle difference can be generated.

  When the slider 21 moves relative to the input shaft 9 and the output shaft 10 in the direction of the rotation shaft 2a, the slider 21 moves relative to at least one of the input shaft 9 and the output shaft 10 around the rotation shaft 2a. Is rotating. As a result, the input shaft 9 and the output shaft 10 rotate relatively, and the rotation angle of the input shaft 9 and the rotation angle of the output shaft 10 can be made different.

  The input side angle and the output side angle are preferably smaller than 90 degrees. According to this, by moving the slider 21 in the direction of the rotating shaft 2a, the input shaft 9 and the output shaft 10 can be rotated without moving in the direction of the rotating shaft 2a. As shown in the input shaft 9, for example, when the input side angle is 0 (zero) degree, even if the slider 21 is moved in the direction of the rotating shaft 2a, the input shaft 9 is not rotated in the direction of the rotating shaft 2a. It can also be removed. That is, if only one of the input side angle and the output side angle is 0 degree, the slider 21 is moved in the direction of the rotating shaft 2a, so that one (for example, the input shaft 9) is not rotated. In addition, only the remaining one (for example, the output shaft 10) can be rotated. If the angle is 0 degree, the input side groove 9a or the output side groove 10a is arranged at a right angle to the rotational direction, so that a large frictional force can be easily generated, and the steering torque Fi is reliably transmitted to the slider 21. Or the steering torque Fi can be transmitted from the slider 21.

  That is, when one of the input side angle and the output side angle is 0 degree, the slider 21 rotates relative to one of the input shaft 9 and the output shaft 10 (for example, the input shaft 9). Without moving relatively in the direction of the rotating shaft 2a, and relatively moving in the direction of the rotating shaft 2a relative to the other (for example, the output shaft 10) with respect to one (input shaft 9). Rotate. Since the slider 21 does not rotate relative to one of the input shaft 9 and the output shaft 10 (input shaft 9), the slider 21 and the one (input shaft 9) have the same rotational speed and the same rotation angle. Can only rotate. The slider 21 rotates relative to the other (output shaft 10), and the other (output shaft 10) rotates relative to one (input shaft 9). it can.

  Then, due to the movement of the slider 21 in the direction of the rotation axis 2a, at least one of the input shaft 9 and the output shaft 10 rotates by obtaining a rotational force, and the input shaft 9 and the output shaft 10 rotate relatively. This rotation is independent from the rotation by the steering torque Fi transmitted from the input shaft 9 to the output shaft 10 via the slider 21. For this reason, these two types of rotation can be superimposed on the output shaft 10 (Fo = Fi + Fadd). That is, the linear slide force Fadd is converted into an assisting rotational force that can be added to the steering force Fo. Similarly, the steering angle θo also includes the steering wheel angle θi and the rotation angle difference between the input shaft 9 and the output shaft 10 caused by the linear slide force Fadd, specifically, the output caused by the linear slide force Fadd according to FIG. The rotation angle θadd of the shaft 10 can be superimposed (θo = θi + θadd). Note that the rotation angle θadd of the output shaft 10 caused by the linear slide force Fadd can be obtained by the equation θadd = 2π × Sadd / Sleado. Here, Sledo is a distance that the output shaft 10 moves relative to the input shaft 9 in the direction of the rotation axis 2 a when the output shaft 10 makes one rotation relative to the input shaft 9. Specifically, according to FIG. 6, Sledo is a distance that the output shaft 10 moves relative to the slider 21 in the direction of the rotation axis 2 a when the output shaft 10 makes one rotation relative to the slider 21. .

  As described above, the steering angle ratio can be changed, and the first embodiment can be completed with a simple and inexpensive structure in which the linear slide force generating means and the slider 21 are added to the input shaft 9 and the output shaft 10. is made of. Further, when the vehicle steering assist device fails, the slider 21 is stopped moving relative to the input shaft 9 and the output shaft 10 in the direction of the rotary shaft 2a. Only the relative rotation of the input shaft 9 and the output shaft 10 due to movement can be easily stopped. As described above, the vehicle steering assist device of the first embodiment can easily construct a fail-safe configuration.

  The linear slide force generating means determines an actual slide amount Sadd that moves the slider 21 in the direction of the rotation shaft 2a according to the handle angle θi of the steering wheel 11 (see FIG. 1) rotated by the steering torque Fi. And a slide amount determining means. According to this, the linear slide force Fadd can be generated so that the slider 21 moves the actual slide amount Sadd.

  FIG. 7 is a block diagram of the control means 3 (see FIG. 1) constituting the linear slide force generating means. The control means 3 has a slide amount determining means. The slide amount determining means includes a signal corresponding to the steering wheel angle θi, a signal corresponding to the vehicle speed, and a loss corresponding to whether or not the vehicle steering assist device has failed. An input means 31 for inputting a fall signal, an offset rotation angle determination means 32, an offset handle angle calculation means 34, a basic slide amount determination means 35, a ratio determination means 33, and a ratio-dependent actual slide amount calculation means 36 and output means 37 for outputting a drive current D for moving the slider 21 in the direction of the rotation shaft 2a by the actual slide amount Sadd based on a signal corresponding to the actual slide amount Sadd. When the output means 37 receives the failure signal, the output means 37 outputs a drive current D that stops the movement of the slider 21 in the direction of the rotating shaft 2a, and locks the motor 28. Note that the movement of the slider 21 in the sliding direction may be constrained by providing a mechanical stopper in the linear sliding force generating means.

  The offset rotation angle determination means 32 determines an offset rotation angle for offsetting the steering wheel angle θi according to the vehicle speed. The offset rotation angle determination means 32 may determine the offset rotation angle using a vehicle speed-offset rotation angle database that can extract the offset rotation angle according to the vehicle speed.

  The offset handle angle calculation means 34 subtracts the offset rotation angle from the measured handle angle θi to calculate the offset handle angle.

  The basic slide amount determination means 35 determines a basic slide amount for moving the slider 21 according to the offset handle angle. The basic slide amount determination means 35 may determine the basic slide amount using a handle angle-slide amount database from which the basic slide amount can be extracted according to the offset handle angle.

  Ratio determining means 33 determines the ratio according to the vehicle speed. The ratio determining means 33 may determine the ratio using a vehicle speed-ratio database from which the ratio can be extracted according to the vehicle speed.

  The ratio-dependent actual slide amount calculation means 36 integrates the ratio and the basic slide amount to calculate the actual slide amount.

  According to this control means 3, by changing the actual slide amount Sadd with respect to the steering wheel angle θi according to the steering wheel angle θi and the vehicle speed, it is possible to perform the steering angle ratio variable control that changes the steering angle θo as a result. . As a result, it is possible to achieve both improvement in handling performance in the low speed range, improvement in turnability in the medium speed range, and improvement in stability in the high speed range.

FIG. 8A shows the relationship of the rotation angle θo of the output shaft 10 with respect to the handle angle θi. Basically, the rotation angle θo of the output shaft 10 with respect to the handle angle θi is considered to have a proportional relationship through the origin O1. Here, by providing an offset rotation angle according to the vehicle speed, a dead zone can be provided for the steering wheel angle θi. In the dead zone, the rotation angle θo of the output shaft 10 is constant at 0 (zero) even if the handle angle θi is changed. Here, if the origin O ₁ is moved by the offset rotation angle to be the origin O ₂ , the offset handle angle obtained by subtracting the offset rotation angle from the handle angle has a proportional relationship with the rotation angle θo, and the basic shape Can be handled in the same way. The offset handle angle calculation means 34 performs such subtraction.

FIG. 8B shows the relationship between the actual slide amount Sadd and the handle angle θi when setting the offset rotation angle. In order to provide the offset rotation angle, even if the steering wheel 11 is rotated by the offset rotation angle, the output shaft 10 is rotated by the offset rotation angle by the steering wheel 11 but is reversely rotated by the slider 21 by the offset rotation angle. , Cancel each other and do not rotate. The actual slide amount for reversely rotating the output shaft 10 by the offset rotation angle is the offset slide amount shown in FIG. By moving the origin from the origin O ₁₁ to the origin O ₁₂ , the coordinate system of the handle angle / slide amount database used in the basic slide amount determination means 35 can be used without change.

  A new offset slide amount determining means may be provided to determine the offset slide amount for offsetting the steering wheel angle θi according to the vehicle speed. Further, the offset slide amount determination means may determine the offset slide amount using a vehicle speed-offset slide amount database capable of extracting the offset slide amount according to the vehicle speed.

  FIG. 9A is a graph showing the relationship of the rotation angle θo of the output shaft 10 with respect to the offset handle angle θi, and FIG. 9B is a graph showing the relationship of the actual slide amount Sadd with respect to the offset handle angle θi. is there.

  For example, in order to realize the case where the steering angle ratio is 2, such that the rotation angle θo of the output shaft 10 rotates 180 degrees when the steering wheel angle θi rotates 90 degrees as shown by the straight line a in FIG. As shown by the straight line a in FIG. 9B, the actual slide amount Sadd may be set such that when the handle angle θi rotates 90 degrees, the output shaft 10 rotates 90 degrees in the same rotation direction.

  For example, as shown by the straight line b in FIG. 9A, the rotation angle θo of the output shaft 10 rotates so that the steering angle ratio becomes 1 until the steering wheel angle θi rotates by 90 degrees, and the steering wheel angle θi becomes 90. In order to realize a case where the rotation angle θo of the output shaft 10 is rotated so that the rudder angle ratio becomes 2 when the angle exceeds the degree, the steering wheel angle θi is set as shown by the straight line b in FIG. The actual slide amount Sadd is constant at 0 (zero) up to 90 ° rotation, and the actual slide amount is set so that the output shaft 10 has the steering angle ratio 2 in the same rotational direction as the input shaft 9 after exceeding 90 °. Sadd may be set.

  For example, as shown by a straight line c in FIG. 9A, the rotation angle θo of the output shaft 10 also rotates so that the steering angle ratio becomes 0.5 until the steering wheel angle θi rotates 90 degrees, and the steering wheel angle θi. In order to realize a case where the rotation angle θo of the output shaft 10 is rotated so that the rudder angle ratio becomes 0 (zero) when the angle exceeds 90 degrees, as shown by a straight line c in FIG. Until the steering wheel angle θi is rotated by 90 degrees, the actual slide amount Sadd may be set so that the steering angle ratio is 0.5 in the rotation direction opposite to that of the input shaft 9, and the steering wheel angle θi is After exceeding 90 degrees, the actual slide amount Sadd may be set so that the steering angle ratio becomes 0 in the direction of rotation of the output shaft 10 opposite to that of the input shaft 9.

  FIG. 10 is a block diagram (No. 2) of the control means 3 (see FIG. 1) constituting the linear slide force generating means. The control means 3 shown in the block diagram of FIG. 7 can be used alone or in combination. it can. And the control means 3 has the said slide amount determination means, The said slide amount determination means is a signal according to a steering wheel angle | corner (theta) i, a signal according to a vehicle speed, a signal according to a yaw rate, The steering assistance apparatus for vehicles The input means 31 for inputting a failure signal corresponding to the presence or absence of the failure, the target yaw rate determining means 38, the yaw rate deviation calculating means 39, the yaw rate dependent actual slide amount determining means 40, and the actual slide amount Sadd. And output means 37 for outputting a drive current D for moving the slider 21 in the direction of the rotary shaft 2a by the actual slide amount Sadd based on the corresponding signal. When receiving the failure signal, the output means 37 outputs a drive current D that stops the slider 21 from moving in the direction of the rotary shaft 2a.

  The target yaw rate determining means 38 determines a target yaw rate that stabilizes the vehicle based on the measured steering angle and vehicle speed. The target yaw rate determination means 38 may determine the target yaw rate using a vehicle speed-handle angle-target yaw rate database that can extract a target yaw rate that stabilizes the vehicle based on the measured steering wheel angle and vehicle speed. .

  The yaw rate deviation calculating means 39 calculates the yaw rate deviation by subtracting the measured actual yaw rate from the target yaw rate.

  The yaw rate dependent actual slide amount determining means 40 includes a yaw rate dependent actual slide amount determining means 40 for determining the actual slide amount in accordance with the yaw rate deviation. The yaw rate dependent actual slide amount determination means 40 may determine the actual slide amount using a yaw rate deviation-slide amount database from which the actual slide amount can be extracted according to the yaw rate deviation.

  According to this control means 3, the actual slide amount can be adjusted in the direction of correction to reduce the deviation between the actual yaw rate of the actual vehicle and the target yaw rate that is the model output value. Automatic control of the turning angle θo can be performed.

(Modification 1 of the first embodiment)
Fig.11 (a) is sectional drawing of the principal part of the steering assistance apparatus for vehicles which concerns on the modification 1 of the 1st Embodiment of this invention. The vehicle steering assist device according to the first modification of the first embodiment is different from the vehicle steering assist device according to the first embodiment in that an input-side groove 9a is formed in the slider 21 with respect to the input shaft 9, and the input side A recess 9 c is formed in the input shaft 9. Further, the output shaft 10 is different in that an output side groove 10 a is formed in the slider 21 and an output side depression 10 c is formed in the output shaft 10. According to the first modification of the first embodiment, the same effect as that of the first embodiment can be obtained.

(Modification 2 of the first embodiment)
FIG.11 (b) is sectional drawing of the principal part of the steering assistance apparatus for vehicles which concerns on the modification 2 of the 1st Embodiment of this invention. The difference between the vehicle steering assist device of the second modification of the first embodiment and the vehicle steering assist device of the first modification of the first embodiment is that the input side groove 9a is parallel to the direction parallel to the rotation shaft 2a. It is not a point. Moreover, the point which the output side groove | channel 10a is parallel to the rotating shaft 2a differs. According to the second modification of the first embodiment, the same effects as those of the first embodiment and the first modification of the first embodiment can be obtained.

(Second Embodiment)
FIG. 12 is a cross-sectional view of a main part of the vehicle steering assist apparatus according to the second embodiment of the present invention. The vehicle steering assist device of the second embodiment is different from the vehicle steering assist device of the first embodiment in that the slider holder 24 constituting the linear slide force generating means is fixed to a housing 27. It is a point. In this connection, the worm wheel 25 for moving the slider holder 24, the worm gear 26, the slide key groove 27a, the motor 28, and the control means 3 are omitted.

  The slider 21 and the slider holder 24 have slider facing surfaces that are parallel to the rotating shaft 2a and face each other. At least one of the slider facing surfaces has an angle of 0 with respect to the direction parallel to the rotating shaft 2a. A slider groove 21a is formed in a direction exceeding the angle and smaller than 90 °. The slider 21 is rotated by receiving the steering torque Fi from the input shaft 9, and the slider ball 22 moves relatively in the slider groove 21 a, so that the slider 21 moves in the direction of the rotary shaft 2 a with respect to the slider holder 24. The linear slide force Fadd can be generated and the output shaft 10 can be rotated by θadd. As in the first embodiment, since the handle angle θi of the input shaft 9 is transmitted to the output shaft 10 as it is, the turning angle θo is the sum of the handle angles θi and θadd (θo = θi + θadd). Thus, the steering angle ratio can be changed also by the second embodiment. The actual slide amount Sadd of the slider 21 resulting from the linear slide force Fadd can be obtained by the equation Sadd = Sleads × θsr / 2π. Here, Sleads is a distance that the slider 21 moves relatively in the direction of the rotation shaft 2 a when the slider 21 makes one rotation relative to the slider holder 24. Θsr is the rotation angle of the slider 21 and is equal to the handle angle θi of the input shaft 9.

  And the steering angle ratio with respect to the steering wheel angle of the steering wheel 11 (refer FIG. 1) can be arbitrarily adjusted to a nonlinear characteristic by adjusting the direction and inclination of the slider groove | channel 21a. Since a driving device such as the motor 28 and the control means 3 are not required, an inexpensive system can be provided.

It is a lineblock diagram of a steering system which has a steering support device for vehicles concerning a 1st embodiment of the present invention. 1 is an exploded perspective view of a vehicle steering assist device according to a first embodiment of the present invention. It is sectional drawing of the steering assistance apparatus for vehicles which concerns on the 1st Embodiment of this invention, and has shown the case where an input shaft rotates. It is sectional drawing of the AA direction of FIG. It is sectional drawing of the BB direction of FIG. It is sectional drawing of the steering assistance apparatus for vehicles which concerns on the 1st Embodiment of this invention, and has shown the case where a slider moves. It is a block diagram (the 1) of a control means. (A) is a graph showing the relationship of the rotation angle of the output shaft to the handle angle, displaying the offset rotation angle and the offset handle angle, (b) is a graph showing the relationship of the actual slide amount to the handle angle, The offset slide amount is displayed. (A) is a graph which shows the relationship of the rotation angle of the output shaft with respect to the offset handle angle, (b) is a graph which shows the relationship of the actual slide amount with respect to the offset handle angle. It is a block diagram (the 2) of a control means. (A) is sectional drawing of the steering assistance apparatus for vehicles which concerns on the modification 1 of the 1st Embodiment of this invention, (b) is the steering for vehicles which concerns on the modification 2 of the 1st Embodiment of this invention. It is sectional drawing of an assistance apparatus. It is sectional drawing of the steering assistance apparatus for vehicles which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering system 2 Steering assistance apparatus main body for vehicles 3 Control apparatus 4 Steering power assist system main body 5 Torque sensor 6 Handle angle measurement means 7 Vehicle speedometer 8 Yaw rate measurement means 9 Input shaft 9a Input side groove 9b Input side ball 9c Input side depression 10 Output Shaft 10a Output side groove 10b Output side ball 10c Output side depression 11 Steering wheel 12 Steering shaft 13 Connection shaft 14 Pinion 15 Rack 16 Tie rod 17 Knuckle arm 18 Steering wheel 19 Universal joint 21 Slider 21a Slider groove 22 Slider ball 23 Retainer 24 Slider holder 24a Slider groove 24b Slide key 24c External screw tooth 25 Worm wheel 25a Internal screw tooth 26 Worm gear 27 Housing 27a Slide key groove 2 8 motor 31 input means 32 offset rotation angle determination means 33 ratio determination means 34 offset handle angle calculation means 35 basic slide amount determination means 36 ratio dependent actual slide amount calculation means 37 output means 38 target yaw rate determination means 39 yaw rate deviation calculation means 40 Actual slide amount determination means depending on the yaw rate

Claims (2)

In a vehicle steering assist device having an input shaft to which a steering rotational force of a steering wheel is transmitted, and an output shaft for transmitting a steering force according to the steering rotational force to a steered wheel,
Linear slide force generating means for generating a linear slide force corresponding to at least one of a steering angle, a vehicle speed, and a yaw rate;
A slider that converts the linear sliding force into an assisting rotational force that can be added to the steering force;
The linear slide force generating means includes a motor, a worm wheel that rotates at a reduced speed via a worm gear by the rotation of the motor, and a rotation of the worm wheel while rotatably supporting the slider around the rotation shaft of the input shaft. A slider holder that moves in the direction of the rotation axis of the input shaft or the output shaft;
The slider and the input shaft are relatively non-rotatable around the rotation axis of the input shaft and can be relatively displaced in the direction of the rotation axis of the input shaft;
The slider receives the steering rotational force from the input shaft and transmits it to the output shaft to generate the steering force, and the slider holder moves the linear slide force to each of the input shaft and the output shaft. Acting in the direction of the rotation axis, and moving the input shaft and the output shaft relative to each other in the direction of the rotation axis, the input shaft and the output shaft rotate relatively ,
When the motor is stopped and the slider is stopped accordingly, the input shaft and the output shaft do not rotate relative to each other, and at the time of failure, each of the input shaft and the output shaft by the slider A steering assist device for a vehicle, which stops all relative movements . When the slider moves relative to each of the input shaft and the output shaft in the direction of the rotation axis, the slider moves around the rotation axis relative to at least one of the input shaft and the output shaft. The steering assist device for a vehicle according to claim 1 , wherein the steering assist device is for a vehicle.

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