JP5191325B2 - Steer-by-wire steering device - Google Patents

Description

  The present invention relates to a steer-by-wire steering apparatus in which steering is performed with a steering wheel that is not mechanically connected to a steering shaft for turning.

In this type of steer-by-wire type steering device, there has been proposed a configuration in which a steered wheel is steered by an auxiliary motor even if a steered motor that steers steered wheels fails (Patent Document 1). .
In addition, in a steer-by-wire type steering device in which the left and right wheels in the front wheel system or the rear wheel system are independently steered, a method of obtaining braking force by controlling each of the left and right wheels in a toe-in or toe-out state when an abnormality occurs (Patent Document 2).
JP-A-2005-349845 JP 2005-263182 A

The technology disclosed in Patent Document 1 has a fail-safe function for operating the auxiliary motor when the steering motor fails. However, when the steering motor is normal, the auxiliary motor does not function at all. It is uneconomical.
In addition, the technique disclosed in Patent Document 2 is a method of independently turning each wheel, but because an abnormal wheel becomes uncontrollable, it cannot be normally steered to take an action to avoid danger. There's a problem.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a steer-by-wire steering device that can perform steering by diverting a toe angle adjusting motor to a steering drive source even if a steering motor that steers the wheels fails. It is to be.

The steer-by-wire steering device of the present invention includes a steering wheel that is not mechanically connected to a steering shaft for steering, a steering angle sensor that detects a steering angle of the steering wheel, and a reaction torque applied to the steering wheel. An operating state detection signal including a steering reaction force motor to be applied and a steering control unit that controls the steering reaction force motor and a steering motor that drives the steering shaft, and includes a steering angle signal detected by the steering angle sensor; In the steer-by-wire type steering device in which the steering motor is controlled by the steering control unit based on the steering wheel, a toe angle adjusting mechanism having a toe angle adjusting motor for adjusting a toe angle is provided separately from the steering motor. When the steering motor fails, the steering motor is separated from the steering shaft and steered by the toe angle adjusting motor. Characterized in that a switching means to I.
According to this configuration, when the steering motor for turning the wheels fails, the switching motor is provided so that the steering motor is separated from the steering shaft and steered by the toe angle adjusting motor. Even if a failure occurs, the toe angle adjusting motor can be diverted to the turning drive source. Even when the steering motor is normal, the toe angle adjusting motor functions as a drive source for adjusting the toe angle of the wheels. Therefore, it can be set as an economical structure compared with the case of the prior art which provides the auxiliary motor operated only when the steering motor fails.

In the present invention, when the toe angle adjusting motor fails, a toe angle fixing means may be provided in which the toe angle adjusting mechanism is set in a fixed state and only the steering motor performs turning.
In the case of this configuration, it is possible to prevent erroneous toe angle adjustment from being performed while the toe angle adjusting motor has failed.

  In the present invention, the steering shaft may have a ball screw part at a part thereof, and the turning motor may turn by turning a ball nut screwed to the ball screw part.

  In the present invention, the toe angle adjusting mechanism includes a spline tooth formed on a portion different from the ball screw portion of the steering shaft, a spline nut meshing with the spline tooth, and a toe angle for rotationally driving the spline nut. An adjustment motor, and a toe angle adjusting screw portion formed on both ends of the steering shaft and screwed with the tie rod. The toe angle adjusting motor rotates the steering shaft together with the spline nut, and the tie rod from the steering shaft is rotated. The toe angle may be adjusted by changing the protruding length. The toe angle adjusting screw portion may be, for example, a trapezoidal screw. Further, the toe angle adjusting screw portion may be provided with a detent.

  In this invention, the toe angle adjusting screw portions at both ends of the steering shaft are reverse screws, and the left and right tie rods protrude by rotation in one direction of the steering shaft, and the left and right tie rods rotate by rotation in the other direction of the steering shaft. It may be set back.

  In this invention, the rotating shafts of the steering motor and toe angle adjusting motor are coaxially arranged, the rotating shaft of the steering motor is detachably fitted, and the rotation of the rotating shaft is transmitted to the ball nut. And a second rotation transmission mechanism for fitting the rotation shaft of the toe angle adjusting motor so that the rotation shaft can be inserted and removed, and transmitting the rotation of the rotation shaft to the spline nut. The means includes a linear motion actuator that moves the rotation shafts of the two motors in the axial direction when the steering motor fails, and a transmission mechanism fixing unit that fixes the second rotation transmission mechanism. While the shaft is moved, the rotation shaft of the toe angle adjusting motor is fitted to the first rotation transmission mechanism instead of the rotation shaft of the steering motor, and the second rotation transmission mechanism is fitted with the transmission mechanism fixing means. It may be fixed.

  In the present invention, the linear actuator may be a linear solenoid or a hydraulic cylinder.

In the present invention, the maximum generated torque of the toe angle adjusting motor may be smaller than the maximum generated torque of the steered motor.
Since the toy angle adjustment by the toe angle adjusting motor and the alternative as the steering drive source when the steering motor fails, the operation that is performed when the vehicle is running is the maximum generated torque during the stationary operation. Is much smaller than the torque required. Accordingly, the toe angle adjusting motor may be smaller than the steering motor.

  The steer-by-wire steering device of the present invention includes a steering wheel that is not mechanically connected to a steering shaft for steering, a steering angle sensor that detects a steering angle of the steering wheel, and a reaction torque applied to the steering wheel. An operating state detection signal including a steering reaction force motor to be applied and a steering control unit that controls the steering reaction force motor and a steering motor that drives the steering shaft, and includes a steering angle signal detected by the steering angle sensor; In the steer-by-wire type steering device in which the steering motor is controlled by the steering control unit based on the steering wheel, a toe angle adjusting mechanism having a toe angle adjusting motor for adjusting a toe angle is provided separately from the steering motor. When the steering motor fails, the steering motor is separated from the steering shaft and steered by the toe angle adjusting motor. Due to the provision of the switching means to I, even if failure is turning motor for turning the wheel, it is possible to perform the turning and diverting toe angle adjusting motor as a driving source of the steering.

  An embodiment of the present invention will be described with reference to the drawings. As shown schematically in FIG. 1, the steer-by-wire steering apparatus includes a steering wheel 1, a steering angle sensor 2, a steering torque sensor 3, a steering reaction force motor 4, and left and right wheels that are steered by a driver. 13 is a steerable axially steerable steering shaft 10 connected via a knuckle arm 12 and a tie rod 11, a steering shaft drive unit 14 for driving the steering shaft 10, a steered angle sensor 8, and a steering. And an ECU (electric control unit) 5 including a controller 5a. The ECU 5 and the steering control unit 5a are configured by a microcomputer and an electronic circuit including a control program thereof.

  The steering wheel 1 is not mechanically connected to a steering shaft 10 for turning. A steering angle sensor 2 and a steering torque sensor 3 are provided for the steering wheel 1 and a steering reaction force motor 4 is connected thereto. The steering angle sensor 2 is a sensor that detects the steering angle of the steering wheel 1. The steering torque sensor 3 is a sensor that detects a steering torque that acts on the steering wheel 1. The steering reaction force motor 4 is a motor that applies reaction force torque to the steering wheel 1.

  FIG. 2 is a sectional view showing details of the steering shaft driving unit 14 that drives the steering shaft 10. The steering shaft drive unit 14 includes a steering mechanism 15 that steers the wheel 13 by moving the steering shaft 10 in the axial direction, a toe angle adjustment mechanism 16 that adjusts a toe angle of the wheel 13, and a switching unit 17. And are provided.

  The steering mechanism 15 includes a ball screw portion 10a formed on a part of the steering shaft 10, a ball nut 18 screwed into the ball screw portion 10a, a turning motor 6, and the rotation of the turning motor 6. A rotation transmission mechanism 21 that decelerates the rotation of the shaft 6a and transmits the rotation to the ball nut 18; The ball nut 18 is supported by a housing 20 of the steering shaft drive unit 14 via a bearing 19 so as to be rotatable only. The steering motor 6 is installed outside the housing 20 in a posture in which the rotation shaft 6 a is aligned in parallel with the steering shaft 10. By transmitting the rotation of the rotation shaft 6a of the steering motor 6 to the ball nut 18 via the rotation transmission mechanism 21, the steering shaft 10 is moved in the axial direction, and the wheel 13 is steered. The rotation transmission mechanism 21 is fixed to one end of the rotating shaft 6a of the steering motor 6 so as to be removably fitted through a spiran (not shown) and the outer diameter surface of the ball nut 18. Input gear 23 and an intermediate gear 24 interposed between the two gears 22 and 23.

  The toe angle adjusting mechanism 16 includes a spline tooth 10b formed on a portion different from the ball screw portion 10a of the steering shaft 10, a spline nut 25 meshing with the spline tooth 10b, a toe angle adjusting motor 7, A second rotation transmission mechanism 26 that decelerates the rotation of the rotary shaft 7a of the toe angle adjusting motor 7 and transmits it to the spline nut 25 and the left and right tie rods 11 formed at both ends of the steering shaft 10 are screwed together. And a toe angle adjusting screw portion 10c. The spline teeth 10b and the spline nut 25 may be in sliding contact or in rolling contact. The spline nut 25 is supported by the housing 20 of the steering shaft drive unit 14 via a bearing 32. In the housing 20, the toe angle adjusting motor 7 is installed in such a posture that its rotating shaft 7 a is coaxially aligned with the rotating shaft 6 a of the steering motor 6. The rotation of the rotating shaft 7a of the toe angle adjusting motor 7 is transmitted to the spline nut 25 through the second rotation transmission mechanism 26, and the steering shaft 10 is rotated together with the spline nut 25, so that the tie rod 11 from the steering shaft 10 is rotated. The toe angle of the wheel 13 is adjusted by changing the protruding length of. The second rotation transmission mechanism 26 includes an output gear 27 detachably fitted to one end of the rotating shaft 7a of the toe angle adjusting motor 7, and an input gear 28 fixed to the outer diameter surface of the spline nut 25. The intermediate gear 29 is interposed between the two gears 27 and 28. The toe angle adjusting screw portions 10c at both ends of the steering shaft 10 are female screw portions that are reversely threaded, and the left and right tie rods 11 protrude from each other when the steering shaft 10 rotates in one direction, and the steering shaft 10 moves in the other direction. The left and right tie rods 11 are configured to retreat with each other by rotation. The toe angle adjusting screw portion 10c is, for example, a trapezoidal screw. Further, the toe angle adjusting screw portion 10c may be provided with a detent.

  The other end of the rotating shaft 25a of the toe angle adjusting motor 25 is pressed against one end of the rotating shaft 6a of the steering motor 6 into which the output gear 22 of the first rotation transmission mechanism 21 is detachably fitted. The switching means 17 for turning the toe angle adjusting motor 25 as a drive source when the turning motor 6 fails is a linear motion actuator for moving the rotary shafts 6a and 7a of the motors 6 and 7 in the axial direction. 30 and a transmission mechanism fixing means 31 for fixing the second rotation transmission mechanism 26 (that is, in a fixed state incapable of operation). The linear actuator 30 is composed of, for example, a linear solenoid or a hydraulic cylinder, and its action rod 30a is pressed against the end opposite to the end where the output gear 22 of the rotating shaft 6a of the steered motor 6 is fitted. Placed in.

  FIG. 2 shows a state where the linear actuator 30 is not operated, that is, a state where the steered motor 6 is normal. At this time, the output gear 22 of the first rotation transmission mechanism 21 is detachably fitted to one end of the rotating shaft 6a of the steered motor 6, and the second shaft is connected to one end of the rotating shaft 7a of the toe angle adjusting motor 7. The output gear 27 of the rotation transmission mechanism 26 is in a state of being detachably fitted. The transmission mechanism fixing means 31 is a rotary shaft pressing rod 34 that is spline-fitted into a rod fitting hole 33 provided in the housing 20 and can be moved forward and backward coaxially with the rotary shaft 7a of the toe angle adjusting motor 7. The rotating shaft pressing rod 34 is composed of a coil spring 35 that elastically biases the rotating shaft pressing rod 34 toward the advancing side. The rotating shaft pressing rod 34 is pressed against one end of the rotating shaft 7 a of the toe angle adjusting motor 7.

  FIG. 3 shows a state where the linear actuator 30 is activated, that is, a state where the steered motor 6 has failed. At this time, the operating rod 30a of the linear actuator 30 moves backward, and the rotating shafts 6a and 7a of the motors 6 and 7 are pushed by the rotating shaft pressing rod 34 and move in the axial direction toward the right side of FIG. . By this movement, in the first rotation transmission mechanism 21, one end of the rotating shaft 6a of the steered motor 6 that has been fitted to the output gear 22 until then is released, and instead, a toe angle adjusting motor is released. 7 is engaged with the other end of the rotary shaft 7a, and is engaged with the output gear 22 by a spline (not shown) or the like. That is, the toe angle adjusting motor 7 is connected to the first rotation transmission mechanism 21 in place of the steering motor 6 as a drive source of the steering mechanism 15. On the other hand, in the second rotation transmission mechanism 26, one end of the rotary shaft 7a of the toe angle adjusting motor 7 that has been fitted to the output gear 27 until then is released, and instead, the transmission mechanism fixing means 31 is used. The rotating shaft pressing rod 34 is fitted by a spline or the like. That is, the toe angle adjusting motor 7 is disconnected from the second rotation transmission mechanism 26, and the second rotation transmission mechanism 26 is fixed by the transmission mechanism fixing means 31.

In FIG. 1, the steering control unit 5 a of the ECU 5 controls the steering reaction force motor 4, the steering motor 6, the toe angle adjusting motor 7, and the linear actuator 30 of the switching means 17. In other words, the steering control unit 5a performs a target steering reaction force based on a steering angle signal detected by the steering angle sensor 2, a wheel rotational speed signal detected by a vehicle speed sensor (not shown), and signals of various sensors that detect driving conditions. The steering reaction force motor 4 is controlled by feeding back a steering torque signal detected by the steering torque sensor 3 so that the actual steering reaction force torque matches the target steering reaction force. Further, the steering control unit 5a is provided with a toe angle fixing means 36 for fixing the toe angle adjusting mechanism 16 when the toe angle adjusting motor 7 fails.
Specifically, when the toe angle adjusting motor 7 fails, the toe angle fixing means 36 stops the rotational drive of the steering shaft 10 by the toe angle adjusting motor 7, thereby fixing the toe angle to a constant value. To do. It should be noted that braking means (not shown) or the like for disabling the toe angle adjusting mechanism 16 is provided, and the toe angle fixing means 36 is for fixing the toe angle adjusting mechanism 16 with the braking means being in a braking function operating state. May be.

  Next, the operation of the steer-by-wire steering device at the steering shaft drive unit 14 will be described. When the steered motor 6 is normal, the rotation of the rotating shaft 6a of the steered motor 6 is transmitted to the ball nut 18 via the first rotation transmission mechanism 21 and the toe angle is adjusted as shown in FIG. The rotation of the rotary shaft 7 a of the motor 7 is transmitted to the spline nut 25 via the second rotation transmission mechanism 26. The rotation of the ball nut 18 screwed into the ball screw portion 10a of the steering shaft 10 moves the steering shaft 10 in the axial direction, whereby the wheels 13 are steered. Since the spline nut 25 of the toe angle adjusting mechanism 16 is spline-fitted to the spline teeth 10b of the steering shaft 10, the axial movement of the steering shaft 10 is allowed. The rotation of the spline nut 25 fitted to the spline teeth 10b of the steering shaft 10 rotates the steering shaft 10. By this rotation, the tie rods 11 screwed into the toe angle adjusting screw portions 10c at both ends of the steering shaft 10 advance and retract. Thus, the toe angle is adjusted.

  When the steered motor 6 fails, the linear motion actuator 30 that is a component of the switching means 17 is actuated by a command from the steering control unit 5a of the ECU 5, and the actuating rod 30a moves backward. As a result, the rotating shaft pressing rod 34 of the transmission mechanism fixing means 31 is pushed out, and the rotating shafts 6a and 7a of the steered motor 6 and the toe angle adjusting motor 7 move to the right in the axial direction as shown in FIG. At this time, instead of disengaging the rotation shaft 6a of the steering motor 6 from the output gear 22 of the first rotation transmission mechanism 21, the rotation shaft 7a of the toe angle adjusting motor 7 is engaged with the output gear 22. The drive source of the steering mechanism 15 is switched from the steering motor 6 to the toe angle adjusting motor 7.

  On the other hand, in the second rotation transmission mechanism 26, instead of releasing the fitting of the rotation shaft 7a of the toe angle adjusting motor 7 from the output gear 27, the rotation shaft pressing rod 34 of the transmission mechanism fixing means 31 is replaced with the output gear. 27, the toe angle adjusting mechanism 16 is kept in a fixed state. That is, the toe angle of the wheel 13 is kept constant.

  In the state of FIG. 2 in which both the steering mechanism 15 and the toe angle adjusting mechanism 16 are operating, when the toe angle adjusting motor 7 fails, the toe angle fixing means 36 of the steering control unit 5a in the ECU 5 Then, a stop command is given to the toe angle adjusting motor 7, the toe angle adjusting motor 7 is stopped, and only the steering is performed. Thereby, it is possible to prevent erroneous toe angle adjustment from being performed while the toe angle adjusting motor 7 is lost.

  Thus, in this steer-by-wire type steering apparatus, a toe angle adjusting mechanism 16 having a toe angle adjusting motor 7 for adjusting the toe angle of the wheel 13 is provided separately from the steered motor 6, and the steered motor 6 is lost. Since the switching motor 17 for separating the steered motor 6 from the steering shaft 10 and steering by the toe angle adjusting motor 7 is provided when the car falls, the steered motor 6 for steering the wheels 13 is lost. In addition, the toe angle adjusting motor 7 can be diverted to the turning drive source to perform the turning. Even when the steered motor 6 is normal, the toe angle adjusting motor 7 serves as a drive source for adjusting the toe angle of the wheel 13, so that an auxiliary motor that operates only when the steered motor 6 fails is provided. Compared with the case of the conventional example provided, it can be set as an economical structure.

  The torsion angle adjustment by the toe angle adjustment motor 7 and the replacement as the steering drive source when the steering motor 6 fails is an operation performed when the vehicle travels. Sometimes it is much smaller than the torque required for the steering motor 6. Therefore, the toe angle adjusting motor 7 may be smaller than the steered motor 6.

1 is a block diagram showing a schematic configuration of a steer-by-wire steering device according to an embodiment of the present invention. It is sectional drawing at the time of normal operation of the steering shaft drive part in the steer-by-wire type steering apparatus. It is sectional drawing at the time of the steering motor failure in the steering shaft drive part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steering wheel 2 ... Steering angle sensor 4 ... Steering reaction force motor 5 ... ECU
5a ... Steering controller 6 ... Steering motor 7 ... Toe angle adjusting motor 10 ... Steering shaft 10a ... Ball screw part 10b ... Spline tooth 10c ... Toe angle adjusting screw part 11 ... Tie rod 16 ... Toe angle adjusting mechanism 17 ... Switching Means 18 ... Ball nut 21 ... First rotation transmission mechanism 25 ... Spline nut 26 ... Second rotation transmission mechanism 30 ... Direct acting actuator 31 ... Transmission mechanism fixing means 36 ... Toe angle fixing means

Claims (9)

A steering wheel that is not mechanically connected to a steering shaft for steering, a steering angle sensor that detects a steering angle of the steering wheel, a steering reaction force motor that applies a reaction torque to the steering wheel, and the steering A steering control unit that controls a reaction motor and a steering motor that drives the steering shaft, and the steering motor is controlled based on a driving state detection signal including a steering angle signal detected by the steering angle sensor. In the steer-by-wire steering device that is controlled by the control unit,
A toe angle adjusting mechanism having a toe angle adjusting motor for adjusting a toe angle is provided separately from the steered motor. When the steered motor fails, the steered motor is separated from the steering shaft and the toe angle adjusted. The steer-by-wire type steering apparatus provided with the switching means to perform a steering with the motor for motors.   2. The steer-by-wire steering apparatus according to claim 1, further comprising toe angle fixing means for causing the steering motor to perform only turning with the toe angle adjusting mechanism in a fixed state when the toe angle adjusting motor fails.   3. The steering shaft according to claim 1, wherein the steering shaft has a ball screw portion at a part thereof, and the turning motor performs turning by rotating a ball nut screwed to the ball screw portion. Steer-by-wire steering device.   4. The toe angle adjusting mechanism according to claim 1, wherein the toe angle adjusting mechanism includes a spline tooth formed on a portion different from the ball screw portion of the steering shaft, and a spline nut meshing with the spline tooth. A toe angle adjusting motor that rotationally drives the spline nut, and a toe angle adjusting screw portion that is formed at both ends of the steering shaft and that is screwed with a tie rod. A steer-by-wire steering device that rotates and adjusts the toe angle by changing the protruding length of the tie rod from the steering shaft.   5. The toe angle adjusting screw portions at both ends of the steering shaft are reverse screws, and the left and right tie rods protrude by rotation in one direction of the steering shaft, and the left and right tie rods by rotation in the other direction of the steering shaft. Steer-by-wire steering device that is supposed to move backward.   The rotating shaft of the steering motor and the toe angle adjusting motor is arranged coaxially in any one of claims 1 to 5, and the rotating shaft of the steering motor is removably fitted to the rotating motor. A first rotation transmission mechanism that transmits rotation of the rotation shaft to the ball nut and a rotation shaft of the toe angle adjusting motor are detachably fitted, and second rotation that transmits the rotation of the rotation shaft to the spline nut. The rotation means is provided, and the switching means is a linear motion actuator that moves the rotation shafts of the two motors in the axial direction when the steered motor fails, and a transmission mechanism fixing that fixes the second rotation transmission mechanism. Means for fitting the rotation shaft of the toe angle adjusting motor to the first rotation transmission mechanism instead of the rotation shaft of the steered motor while the rotation shafts of the two motors are moved, and the second rotation The transmission mechanism is fixed by the transmission mechanism fixing means. Ones with the steer-by-wire steering apparatus.   The steer-by-wire steering device according to claim 6, wherein the linear actuator is a linear solenoid.   The steer-by-wire steering apparatus according to claim 6, wherein the linear actuator is a hydraulic cylinder.   9. The steer-by-wire type steering apparatus according to claim 1, wherein a maximum generated torque of the toe angle adjusting motor is smaller than a maximum generated torque of the steered motor.

Images