JP2015044479A - Vehicular steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a sufficient steering angle when a steering wheel and a steering actuator are connected mechanically to each other by a back-up clutch.SOLUTION: A reaction force actuator 2, which imparts a steering reaction force to a steering wheel 1, includes a reduction gear 7 amplifies and transmits rotation torque of a reaction force motor 6 to the steering wheel 1, and a steering side connection shaft 9 which is connected to a back-up clutch 3. The steering side connection shaft 9 is provided so as to be rotated faster than the steering wheel 1 by transmission of rotation from the steering wheel 1 through the reduction gear 7 during steering of the steering wheel 1. A steering actuator 4 includes a rotation transmission path 37 which transmits rotation inputted from the back-up clutch 3 to a steering side connection shaft 25 to a ball nut 21.

Description

  The present invention relates to a steer-by-wire vehicle steering apparatus. Specifically, the steering wheel is steered by the driving force of the steering actuator while the steering wheel and the steered wheel are mechanically separated during normal operation, and the steering wheel and steered wheel are mechanically connected when abnormal. The present invention relates to a vehicle steering apparatus that steers a steered wheel by a steering force of a steering wheel in a state where the steering wheel is turned.

  As a vehicle steering device that steers a steered wheel (generally, the front wheel) of a vehicle in response to steering of the steering wheel by the driver, the steering angle of the steering wheel by the driver is converted into an electrical signal, and based on the electrical signal A steer-by-wire system that steers steered wheels by driving a steer actuator is known.

  A steer-by-wire vehicle steering apparatus usually includes a reaction force actuator that applies a steering reaction force to the steering wheel in accordance with the behavior of the vehicle. The reaction force actuator includes a reaction force motor that generates rotational torque in accordance with the behavior of the vehicle, and a speed reducer that amplifies and transmits the rotational torque of the reaction force motor to the steering wheel.

  In this steer-by-wire vehicle steering device, the steering angle of the steering wheel by the driver is once converted into an electrical signal, and the steering actuator is controlled based on the electrical signal. For example, according to the traveling speed of the vehicle It is possible to change the operation of the steering actuator, which is expected to improve the running stability and motion performance of the vehicle.

  On the other hand, in steer-by-wire vehicle steering devices, it is important to take measures to prevent turning of the steered wheels in the event of a malfunction in the steered actuator or reaction force actuator. .

  As a steer-by-wire vehicle steering system with such countermeasures, the steering wheel and the steering actuator are mechanically disconnected when normal, and the machine between the steering wheel and steering actuator is abnormal when abnormal. The thing which provided the backup clutch which connects automatically is known (patent documents 1-3).

  When this vehicle steering device is used, since the steering wheel and the steering actuator are mechanically disconnected by the backup clutch under normal conditions, the transmission of rotation from the steering wheel to the steering actuator is cut off and The steered wheels can be steered by the driving force of the rudder actuator. Further, in the event of an abnormality, the steering wheel and the steering actuator are mechanically connected by the backup clutch, so that rotation is transmitted from the steering wheel to the steering actuator, and the steered wheels are steered by the steering force of the steering wheel. be able to.

Japanese Patent No. 4347100 Japanese Patent No. 4984504 Japanese Patent No. 4927608

  By the way, in Patent Documents 1 and 2, when the steering wheel and the steering actuator are mechanically connected by a backup clutch, the rotation of the steering wheel is directly input to the steering actuator without being shifted. At this time, the steered wheels can be steered at the maximum turning angle (generally about 30 °) by steering the steering wheel within the range of the maximum steering angle (generally about 1.5 turns to the left and right respectively). In order to achieve this, it is necessary to employ a rack and pinion type steering actuator (for example, FIG. 1 of Patent Document 3).

  The rack-and-pinion type steering actuator is integrally provided with a steering motor that rotates according to the steering angle of the steering wheel, a pinion that receives rotation of the steering motor, and a rack that meshes with the pinion. And a steering rod. The pinion is connected to the steering wheel via a backup clutch. Both ends of the steering rod are connected to the steered wheels via knuckle arms, and when the steering rod moves in the longitudinal direction, the direction of the pair of left and right steered wheels changes in conjunction with this.

  The inventor of the present application examined whether a ball screw type steering actuator could be adopted instead of the rack and pinion type steering actuator as described above. A ball screw type steering actuator includes a steering motor that rotates in accordance with a steering angle of a steering wheel, a ball nut that receives rotation of the steering motor, and a screw that engages the ball nut via a ball. And a steering rod provided integrally with a screw shaft. Both ends of the steering rod are connected to the steered wheels via knuckle arms, and when the steering rod moves in the longitudinal direction, the direction of the pair of left and right steered wheels changes in conjunction with this.

  By adopting this ball screw type steering actuator, it becomes possible to perform steering more smoothly than the rack and pinion method, and it is possible to move the steering rod with a larger load capacity than the rack and pinion method. However, on the other hand, when the steering wheel is steered by the steering force of the steering wheel in a state where the steering wheel and the steering actuator are mechanically connected by the backup clutch in the event of an abnormality, the turning angle is It turns out that there is a shortage of problems.

  That is, the amount of axial movement of the screw shaft when rotation is input to the ball nut of the ball screw mechanism is normally smaller than the amount of axial movement of the rack when rotation is input to the pinion of the rack and pinion mechanism. . On the other hand, in a conventional steer-by-wire vehicle steering system, the path for transmitting rotation from the steering wheel to the backup clutch is a path that does not pass through the reduction gear for amplifying the torque of the reaction force motor. The rotation is transmitted to the backup clutch without being shifted.

  For this reason, when a ball screw type steering actuator is adopted in place of the conventional rack and pinion type steering actuator, the steering wheel is mechanically connected by a backup clutch between the steering wheel and the steering actuator. When the vehicle is steered to the maximum steering angle, the amount of movement of the steering rod becomes small, and there arises a problem that the turning angle of the steered wheels is insufficient.

  The problem to be solved by the present invention is to provide a vehicle steering apparatus that can secure a sufficient turning angle when the steering wheel and the turning actuator are mechanically connected by a backup clutch.

In order to solve the above-described problems, in the present invention, the following configuration is employed in the vehicle steering apparatus.
A steering wheel,
A reaction force actuator that applies a steering reaction force to the steering wheel;
A steering actuator that moves the pair of steered wheels so that the directions of the pair of left and right steered wheels change according to the steering angle of the steering wheel;
In a vehicle steering apparatus having a backup clutch that mechanically disconnects between the steering wheel and the steering actuator when normal, and mechanically connects between the steering wheel and the steering actuator when abnormal,
The reaction force actuator is connected to a reaction force motor that generates a rotational torque that is a source of the steering reaction force, a reduction gear that amplifies and transmits the rotation torque of the reaction force motor to the steering wheel, and the backup clutch A steering-side connecting shaft, and the steering-side connecting shaft rotates faster than the steering wheel by transmitting rotation from the steering wheel via the speed reducer when the steering wheel is steered. Provided in
The steering actuator includes a steering motor that rotates according to a steering angle of the steering wheel, a nut to which rotation of the steering motor is input, a screw engagement with the nut, and rotation of the nut. A screw shaft that moves in the axial direction, a steering rod that is axially moved integrally with the screw shaft to change the direction of the pair of left and right steered wheels, and a steering rod that is coupled to the steered wheels at both ends, and is connected to the backup clutch A steering side connecting shaft, and a rotation transmission path for transmitting rotation input from the backup clutch to the steering side connecting shaft to the nut.
A vehicle steering apparatus characterized by the above.

  If it does in this way, the path which transmits rotation to a backup clutch from a steering wheel serves as a path which accelerates rotation via the reduction gear for torque amplification of a reaction force motor. That is, the speed reducer that amplifies and transmits the rotational torque of the reaction force motor to the steering wheel during normal operation functions as a speed increaser that accelerates and transmits the rotation of the steering wheel to the steering actuator when abnormal. Therefore, when the steering wheel and the steering actuator are mechanically connected by a backup clutch, the steering rod can be moved greatly by steering the steering wheel, and a sufficient turning angle can be secured. It becomes possible.

  A circuit breaker for interrupting the reaction motor drive circuit in the event of an abnormality can be provided. In this case, the reaction motor is prevented from functioning as a generator by shutting off the reaction motor drive circuit with the circuit breaker, so that the driver steers the steering wheel during an abnormality. Therefore, it is possible to reduce the force required for this.

  A torque sensor for detecting the steering torque of the steering wheel may be provided, and a steering assist torque corresponding to the steering torque detected by the torque sensor may be generated by the reaction force motor when an abnormality occurs. In this case, the reaction motor functions as a power steering booster, so that the force required for steering the steering wheel can be remarkably reduced.

  Further, it is possible to provide a circuit breaker that shuts off the drive circuit of the steering motor when an abnormality occurs. In this case, the driving circuit of the steering motor can be blocked by the circuit breaker, so that the steering motor can be prevented from functioning as a generator. It is possible to reduce the force required for steering.

  Further, the nut and the screw shaft are both configured to be a ball screw mechanism in which the screw is engaged through a ball, so that torque loss can be suppressed and transmission efficiency can be increased. As a result, the steering motor can be reduced in size, and the entire vehicle steering apparatus can be made compact.

  In the vehicle steering device of the present invention, when the steering wheel and the steering actuator are mechanically connected by a backup clutch, the torque reduction gear reducer of the reaction force motor functions as a speed increaser. By steering the steering wheel, the steering rod can be moved greatly, and a sufficient turning angle can be secured.

Schematic which shows the steering apparatus for vehicles concerning embodiment of this invention. The figure which shows the structure of the reaction force actuator and steering actuator which are shown in FIG. The figure which shows the other example of the steering actuator shown in FIG. The figure which shows the modification of the steering apparatus for vehicles shown in FIG. The figure which shows the other example of the reduction gear shown in FIG.

  FIG. 1 shows a vehicle steering apparatus according to an embodiment of the present invention. This vehicle steering device converts the steering angle of the steering wheel 1 by the driver into an electric signal, and drives the steered actuator 4 based on the electric signal, thereby steering the steered wheels 5. Is.

  The vehicle steering apparatus includes a steering wheel 1 that is steered by a driver, a reaction force actuator 2 that applies a steering reaction force to the steering wheel 1 according to the behavior of the vehicle, and a pair of left and right depending on the steering angle of the steering wheel 1. A steered actuator 4 that moves the pair of steered wheels 5 so that the directions of the steered wheels 5 (a pair of left and right front wheels in the figure) change, and a backup clutch that switches between transmission and interruption of rotation between the steering wheel 1 and the steered actuator 4 3.

  Since the backup clutch 3 steers the steered wheels 5 by the driving force of the steered actuator 4 in a normal state, the backup clutch 3 is held in a state where the steering wheel 1 and the steered actuator 4 are mechanically separated from each other. In order to enable the steered wheels 5 to be steered by the steering force of the steering wheel 1 when an abnormality occurs such as when a malfunction occurs, the clutch mechanically connects the steering wheel 1 and the steered actuator 4.

  As shown in FIG. 2, the reaction force actuator 2 includes a reaction force motor 6, a speed reducer 7 that amplifies and transmits the rotational torque of the reaction force motor 6 to the steering wheel 1, and a steering angle of the steering wheel 1. It has a limiter device 8 for limiting the range and a steering side connecting shaft 9 connected to the backup clutch 3.

  The limiter device 8 includes a sun gear 11a fixed to a steering shaft 10 that rotates integrally with the steering wheel 1, an annular internal gear 11b that is provided coaxially so as to surround the sun gear 11a, and both the sun gear 11a and the internal gear 11b. And a planetary gear 11c meshing with each other. A plurality of planetary gears 11c are arranged at intervals in the circumferential direction. Each planetary gear 11c is supported so as to be able to rotate, but the position of the rotation shaft 11d is fixed so as not to revolve.

  A pin 12 is fixed to the outer periphery of the internal gear 11 b, and a stopper 14 is fixed to the case 13 of the reaction force actuator 2. When the internal gear 11b is rotated, the pin 12 moves integrally with the internal gear 11b. When the pin 12 comes into contact with the stopper 14, the internal gear 11b cannot be rotated any further. The same applies when the internal gear 11b is rotated in the opposite direction. In this way, the pin 12 and the stopper 14 limit the rotatable range of the internal gear 11b to less than one rotation.

  When the steering wheel 1 is steered, the rotation of the sun gear 11a that rotates integrally with the steering wheel 1 is decelerated at a reduction ratio corresponding to the number of teeth of the sun gear 11a and the internal gear 11b, and is transmitted to the internal gear 11b. It rotates at a slower speed than the steering wheel 1. This reduction ratio is such that when the steering wheel 1 is rotated within the range of the maximum steering angle (generally about 1.5 rotations to the left and right respectively, about 3 rotations as a whole), the rotation of the internal gear 11b is less than 1 rotation. Such a reduction ratio is set. When the steering wheel 1 is steered to the maximum steering angle, the pin 12 comes into contact with the stopper 14, and further rotation of the steering wheel 1 is restricted.

  The limiter device 8 includes a rotation sensor 15 that detects the rotation angle of the internal gear 11b. The rotation sensor 15 detects the absolute position (steering angle) of the steering wheel 1 by detecting the rotation angle after deceleration transmitted from the steering wheel 1. That is, even when the steering wheel 1 is rotated a plurality of times, the internal gear 11b rotates only less than one rotation. Therefore, by detecting the rotation angle of the internal gear 11b with the rotation sensor 15, it can be rotated 360 ° or more. The absolute position of the steering wheel 1 can be detected.

  A resolver can be used as the rotation sensor 15. The resolver includes a rotor 15a that rotates integrally with the internal gear 11b, and an annular stator 15b that is provided so as to surround the rotor 15a. The stator 15 b is fixed to the case 13. The stator 15b has an exciting coil to which a constant alternating voltage is applied from the outside, and two sets of output coils in which an alternating voltage is induced by energization of the exciting coil, and is induced by the two sets of output coils. It is possible to detect the rotation angle of the rotor 15a (rotation angle of the internal gear 11b) by utilizing the property that the AC voltage varies depending on the rotation angle of the rotor 15a. Instead of the resolver, a potentiometer with a built-in variable resistor whose electric resistance value changes in accordance with the rotation angle of the internal gear 11b may be used.

  The reaction force motor 6 includes a rotor 6a connected to the steering side coupling shaft 9 so as to rotate integrally with the steering side coupling shaft 9, and a stator 6b that applies rotational torque to the rotor 6a. The stator 6b is fixed to the case 13. The stator 6b is connected to a drive circuit 16 that supplies electric power for driving the rotor 6a to the stator 6b. The drive circuit 16 has a circuit breaker 17 capable of interrupting a power line that supplies power to the stator 6b.

  A rotation sensor 18 for controlling the reaction force motor 6 is attached to the steering side connecting shaft 9. A resolver can be used as the rotation sensor 18. The resolver includes a rotor 18a that rotates integrally with the steering-side connecting shaft 9, and an annular stator 18b that is provided so as to surround the rotor 18a. The stator 18 b is fixed to the case 13.

  The speed reducer 7 includes a sun gear 7a connected to the steering side coupling shaft 9 so as to rotate integrally with the steering side coupling shaft 9, an annular internal gear 7b coaxially provided so as to surround the sun gear 7a, and a sun gear 7a. And an internal gear 7b, and a planetary carrier 7d that holds the planetary gear 7c so that it can rotate and revolve. A plurality of planetary gears 7c are arranged at intervals in the circumferential direction. The internal gear 7 b is fixed to the case 13. The planet carrier 7d is connected to the steering shaft 10 so as to rotate integrally with the steering shaft 10.

  When the rotor 6a of the reaction motor 6 is rotated, the sun gear 7a rotates integrally with the rotor 6a, and the planetary gear 7c revolves around the sun gear 7a while rotating, and the planet carrier 7d revolves around the planetary gear 7c. And the steering shaft 10 rotates integrally with the planet carrier 7d. The rotational speed of the steering shaft 10 (that is, the rotational speed of the steering wheel 1) is obtained by reducing the rotational speed of the rotor 6a of the reaction force motor 6 with a reduction ratio corresponding to the number of teeth of the sun gear 7a and the internal gear 7b. . At this time, the rotational torque generated by the reaction motor 6 is amplified by the reduction of the rotational speed by the speed reducer 7, and the amplified rotational torque is transmitted to the steering wheel 1 as a steering reaction force.

  When the driver steers the steering wheel 1, the rotation of the steering wheel 1 is transmitted to the steering side connecting shaft 9 via the speed reducer 7. At this time, the rotation of the steering wheel 1 is accelerated by the speed reducer 7, and the rotation after the acceleration is transmitted to the steering side connecting shaft 9, so that the steering side connecting shaft 9 rotates faster than the steering wheel 1. That is, since the steering side connecting shaft 9 is connected to the input side of the speed reducer 7 that decelerates the rotation input from the reaction force motor 6 and outputs it to the steering wheel 1, the steering wheel 1 rotates when the steering wheel 1 rotates. The rotation of the wheel 1 is increased by the speed reducer 7 and transmitted to the steering side connecting shaft 9. The speed increase ratio at this time (that is, the reciprocal of the speed reduction ratio of the speed reducer 7) is obtained by rotating the steering wheel 1 within the range of the maximum steering angle (generally about 1.5 rotations to the left and right respectively, approximately 3 rotations in total). Is set such that a steering rod described later moves with the maximum stroke.

  The turning actuator 4 includes a turning motor 20, a ball nut 21 to which rotation of the turning motor 20 is input, a screw shaft 23 that is screw-engaged with the ball nut 21 via a ball 22, and a screw shaft 23. And a steering side connecting shaft 25 connected to the backup clutch 3.

  The steering motor 20 is controlled to rotate according to the absolute position (steering angle) of the steering wheel 1 detected by the rotation sensor 15. A rotation sensor 27 for controlling the steering motor 20 is attached to the motor shaft 26 of the steering motor 20. A resolver can be used as the rotation sensor 27. The resolver includes a rotor 27a that rotates integrally with the motor shaft 26, and an annular stator 27b that is provided so as to surround the rotor 27a.

  A potentiometer 29 is connected to the motor shaft 26 of the steering motor 20 via a speed reducer 28. The speed reducer 28 decelerates and transmits the rotation of the motor shaft 26 to the potentiometer 29. The reduction ratio of the reduction gear 28 is set to a reduction ratio such that the rotation input to the potentiometer 29 is less than one rotation when the steering rod 24 is moved with the maximum stroke by driving the steering motor 20. The The potentiometer 29 detects the absolute position (axial position) of the steering rod 24 by detecting the rotational angle after deceleration transmitted from the steering motor 20 via the speed reducer 28.

  A driving circuit 30 that supplies power for driving the steering motor 20 to the steering motor 20 is connected to the steering motor 20. The drive circuit 30 includes a circuit breaker 31 capable of interrupting a power line that supplies power to the steering motor 20.

  A drive gear 32 is fixed to the motor shaft 26 of the steering motor 20, and a driven gear 33 that meshes with the drive gear 32 is fixed to the ball nut 21. The ball nut 21 is supported by a bearing 34 so as to be rotatable in a non-movable state in the axial direction. On the other hand, the screw shaft 23 is supported so as to be movable in the axial direction with its rotation constrained. Therefore, when the ball nut 21 is rotated, the screw shaft 23 moves in the axial direction in accordance with the rotation of the ball nut 21.

  A first bevel gear 35 is fixed to the steered side connecting shaft 25, and a second bevel gear 36 that meshes with the first bevel gear 35 is fixed to the motor shaft 26. Here, the first bevel gear 35, the second bevel gear 36, the drive gear 32, and the driven gear 33 rotate the rotation input from the backup clutch 3 to the steered side connecting shaft 25 when the backup clutch 3 is engaged. A rotation transmission path 37 for transmitting to the nut 21 is configured.

  When the backup clutch 3 is energized to a coil (not shown), the backup clutch 3 is in a disconnected state where transmission of rotation in both forward and reverse directions between the steering side connecting shaft 9 and the steered side connecting shaft 25 is cut off, and the coil is deenergized. By doing so, the electromagnetic clutch is in an engaged state in which both forward and reverse rotations are transmitted between the steering side connecting shaft 9 and the steered side connecting shaft 25.

  As shown in FIG. 1, both ends of the steering rod 24 are connected to the steered wheels 5 via knuckle arms 38. When the steering rod 24 moves in the axial direction (the axial direction of the screw shaft 23 shown in FIG. 2), the direction of the pair of left and right steered wheels 5 changes in conjunction with this movement.

  An operation example of the above-described vehicle steering apparatus will be described.

  When the vehicle steering device is normal, the backup clutch 3 is kept disconnected by energization, and the steering wheel 1 and the steering actuator 4 are mechanically disconnected. Then, when the driver steers the steering wheel 1, the rotation angle of the steering wheel 1 is detected by the rotation sensor 15, and the steering motor 20 rotates according to the rotation angle detected by the rotation sensor 15, and the The rotation of the steering motor 20 is transmitted to the ball nut 21 through the drive gear 32 and the driven gear 33 in this order, so that the steering rod 24 moves in the axial direction. Further, the reaction force motor 6 generates a rotation torque according to the behavior of the vehicle, and the rotation torque is amplified by the speed reducer 7 and transmitted to the steering shaft 10, whereby a steering reaction force is applied to the steering wheel 1. .

  On the other hand, when the vehicle steering apparatus is abnormal (for example, when a malfunction occurs in the steering actuator 4 or the reaction force actuator 2), the backup clutch 3 is brought into an engaged state by releasing energization, and the steering wheel 1 and the steering actuator 4 are disconnected. The space is mechanically connected. In this state, when the driver steers the steering wheel 1, the rotation of the steering wheel 1 is the reduction gear 7, the steering side connecting shaft 9, the backup clutch 3, the steered side connecting shaft 25, and the rotation transmission path 37 (that is, the first transmission path 37). By transmitting the bevel gear 35, the second bevel gear 36, the drive gear 32, and the driven gear 33) to the ball nut 21 in order, the steering rod 24 moves in the axial direction. That is, the steered wheels 5 can be steered manually.

  At this time, the steering wheel 1 can be rotated only within the range of the maximum steering angle (generally, about 1.5 rotations to the left and right respectively). However, since the speed reducer 7 functions as a speed increaser, The shaft 9 rotates at a higher rotational speed than the steering wheel 1, and as a result, the steered wheels 5 can be steered with a sufficiently large steered angle.

  For example, if the maximum steering range of the steering wheel 1 is 1.5 turns to the left and right, when the reduction ratio of the speed reducer 7 is 1/16, the steering side connecting shaft 9 will rotate 24 times to the left and right at the maximum. Become. When the gear ratio of the second bevel gear 36 to the first bevel gear 35 is 1/1 and the gear ratio of the driven gear 33 to the drive gear 32 is 1/2, the ball nut 21 is used to steer the steering wheel 1. Makes a maximum of ± 12 rotations. If the lead of the screw shaft 23 is 5 mm, the steered shaft moves ± 60 mm. As described above, when the vehicle steering apparatus having the above-described configuration is used, the steering rod 24 is steered by the steering wheel 1 even when the steering wheel 1 and the steering actuator 4 are mechanically connected by the backup clutch 3. Can be moved greatly, and a sufficient turning angle can be secured.

  By the way, when the rotation of the steering wheel 1 is input to the reaction force motor 6 and the steering motor 20 when the vehicle steering apparatus is abnormal, the reaction force motor 6 and the steering motor 20 function as a generator. Since the reaction force motor 6 and the steering motor 20 each generate a rotational load according to the magnitude of the electric power that is sometimes generated, the steering wheel 1 may become heavy. Therefore, in order to suppress the steering of the steering wheel 1 from becoming heavy, when the vehicle steering device is abnormal, the drive circuit 16 of the reaction force motor 6 is shut off by the circuit breaker 17 and the drive circuit 30 of the steering motor 20 is turned off. Can also be interrupted by the circuit breaker 31. In this way, the reaction force motor 6 and the steering motor 20 can be prevented from functioning as a generator, so that the force required to steer the steering wheel 1 when the vehicle steering device is abnormal is obtained. It becomes possible to suppress.

  In this vehicle steering apparatus, the path for transmitting the rotation from the steering wheel 1 to the backup clutch 3 is a path for increasing the speed of rotation through the torque amplification speed reducer 7 of the reaction force motor 6. That is, the speed reducer 7 that amplifies and transmits the rotational torque of the reaction force motor 6 to the steering wheel 1 at the normal time is used as a speed increaser that accelerates and transmits the rotation of the steering wheel 1 to the steering actuator 4 at the time of abnormality. Function. Therefore, when the steering wheel 1 and the steering actuator 4 are mechanically connected by the backup clutch 3, the steering rod 24 can be moved greatly by the steering of the steering wheel 1, and a sufficient steering angle can be obtained. Can be secured.

  FIG. 3 shows another example of the steering actuator 4. This steering actuator 4 is obtained by adding a toe angle adjusting mechanism 40 to the above embodiment. Portions corresponding to the above embodiment are denoted by the same reference numerals and description thereof is omitted.

  The toe angle adjusting mechanism 40 includes a toe angle adjusting motor 41, a spline nut 42 to which the rotation of the toe angle adjusting motor 41 is input, and the spline nut 42 is prevented from rotating and moves in the axial direction with respect to the spline nut 42. The spline shaft 43 is supported. The spline nut 42 is rotatably supported by a bearing 44 in a non-movable state in the axial direction.

  The spline shaft 43 is arranged coaxially with the screw shaft 23. A female screw 45 is formed at one end of the spline shaft 43, and a male screw 46 formed at one end of the screw shaft 23 is threadedly engaged with the female screw 45. A plurality of grooves 47 extending in the axial direction are formed on the outer periphery of the spline shaft 43. A plurality of balls (not shown) are incorporated between the spline nut 42 and the spline shaft 43, and the balls roll on a groove 47 on the outer periphery of the spline shaft 43, so that the spline shaft 43 and the spline nut 42 move relative to each other in the axial direction. It is possible. The spline nut 42 is provided with a circulation mechanism (not shown) for circulating the balls. When rotation is input to the spline nut 42, torque is transmitted between the spline nut 42 and the spline shaft 43 via the ball, and the spline nut 42 and the spline shaft 43 rotate integrally.

  A drive gear 49 is fixed to the motor shaft 48 of the toe angle adjusting motor 41. A driven gear 50 that meshes with the drive gear 49 is fixed to the spline nut 42. A rotation sensor 51 for controlling the toe angle adjusting motor 41 is attached to the motor shaft 48 of the toe angle adjusting motor 41. As the rotation sensor 51, a resolver including a rotor 51a that rotates integrally with the motor shaft 48 and an annular stator 51b provided so as to surround the rotor 51a can be used. A potentiometer 53 is connected to the motor shaft 48 of the toe angle adjusting motor 41 via a speed reducer 52.

  When the toe angle adjusting motor 41 is rotated in the toe angle adjusting mechanism 40 described above, the rotation of the toe angle adjusting motor 41 is transmitted to the spline nut 42 via the drive gear 49 and the driven gear 50 in this order. When the spline nut 42 rotates, the male screw 46 and the female screw 45 rotate relative to each other, so that the screwing depths of the male screw 46 and the female screw 45 change. As a result, the spline shaft 43 moves in the axial direction, and The angle changes.

  When the toe angle adjusting motor 41 is rotated, of the pair of left and right steered wheels 5 (that is, the steered wheels 5 on the spline shaft 43 side and the steered wheels 5 on the screw shaft 23 side), the steered wheels 5 only on the spline shaft 43 side. The toe angle changes. To adjust the toe angle of the steered wheel 5 on the opposite side, both the steered motor 20 and the toe angle adjusting motor 41 are rotated so that the axial positions of the spline shaft 43 and the screw shaft 23 are adjusted. Change each. In this way, toe-in and toe-out can be adjusted.

  FIG. 4 shows a vehicle steering apparatus according to a modification of the above embodiment.

  In the above embodiment, the drive circuit 16 of the reaction force motor 6 is interrupted by the circuit breaker 17 when the vehicle steering device is abnormal. However, in the modification shown in FIG. Is used as a drive source for electric power steering, a torque sensor 54 for detecting the steering torque of the steering wheel 1 is provided on the steering shaft 10.

  When the vehicle steering apparatus is abnormal, the backup clutch 3 is fastened and the steering wheel 1 and the steering actuator 4 are mechanically connected as in the above embodiment. In this state, when the driver steers the steering wheel 1, the reaction force motor 6 shown in FIG. 2 generates steering assist torque according to the steering torque detected by the torque sensor 54. In this case, the reaction force motor 6 functions as a power steering booster, so that the force required for steering the steering wheel 1 can be significantly reduced.

  In the above embodiment, the reduction gear 7 for amplifying the rotational torque transmitted from the reaction force motor 6 to the steering wheel 1 has been described as an example of a single-stage planetary gear reduction mechanism. However, as shown in FIG. A two-stage planetary gear speed reduction mechanism in which the planetary gear mechanisms shown in the embodiment are connected in series may be used, and other types of speed reducers (for example, the roller speed reducer disclosed in Japanese Patent Publication No. 2-28027) may be used. May be used.

  In the above embodiment, the ball screw mechanism has been described as an example, but a slide screw mechanism that does not involve the ball 22 may be employed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Reaction force actuator 3 Backup clutch 4 Steering actuator 5 Steering wheel 6 Reaction force motor 7 Reduction gear 9 Steering side connection shaft 16 Drive circuit 17 Breaker 20 Steering motor 21 Ball nut 22 Ball 23 Screw shaft 24 Steering Rod 25 Steering side connecting shaft 30 Drive circuit 31 Breaker 37 Rotation transmission path 54 Torque sensor

Claims (5)

Steering wheel (1),
A reaction force actuator (2) for applying a steering reaction force to the steering wheel (1);
A steering actuator (4) that moves the pair of steered wheels (5) so that the directions of the pair of left and right steered wheels (5) change according to the steering angle of the steering wheel (1);
When normal, the steering wheel (1) and the steering actuator (4) are mechanically disconnected, and when abnormal, the steering wheel (1) and the steering actuator (4) are mechanically connected. In a vehicle steering system having a backup clutch (3),
The reaction force actuator (2) amplifies the reaction torque motor (6) that generates the rotation torque that is the basis of the steering reaction force and the rotation torque of the reaction force motor (6) to the steering wheel (1). And a steering side connecting shaft (9) connected to the backup clutch (3). The steering side connecting shaft (9) is used for steering the steering wheel (1). Sometimes it is provided to rotate faster than the steering wheel (1) by transmitting rotation from the steering wheel (1) via the speed reducer (7),
The steering actuator (4) includes a steering motor (20) that rotates according to a steering angle of the steering wheel (1), and a nut (21) to which rotation of the steering motor (20) is input. And a screw shaft (23) that engages with the nut (21) and moves in the axial direction by the rotation of the nut (21), and moves axially integrally with the screw shaft (23) and moves to a pair of left and right rollers. A steering rod (24) having both ends coupled to the steered wheel (5) so as to change the direction of the steered wheel (5); a steered side coupling shaft (25) coupled to the backup clutch (3); A rotation transmission path (37) for transmitting rotation input from the backup clutch (3) to the steered side connecting shaft (25) to the nut (21);
A vehicle steering apparatus characterized by the above.   The vehicle steering apparatus according to claim 1, further comprising a circuit breaker (17) for interrupting the drive circuit (16) of the reaction force motor (6) in the event of an abnormality.   A torque sensor (54) for detecting the steering torque of the steering wheel (1) is provided, and in the case of abnormality, a steering assist torque corresponding to the steering torque detected by the torque sensor (54) is provided by the reaction force motor (6). The vehicle steering apparatus according to claim 1, which occurs.   The vehicle steering device according to any one of claims 1 to 3, further comprising a circuit breaker (31) for interrupting the drive circuit (30) of the steering motor (20) in the event of an abnormality.   The vehicle steering apparatus according to any one of claims 1 to 4, wherein the nut (21) and the screw shaft (23) are a ball screw mechanism in which both are screw-engaged via a ball (22).

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