JP2015089694A - Vehicular steering device, and position detection method for turning wheel in the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular steering device capable of performing turning of a turning wheel in a steer-by-wire method just after a power supply is turned on.SOLUTION: A vehicular steering device includes an absolute position detector 15 of a turning shaft 5, a reference position detector 16 of the turning shaft 5, a rotation detector 17 of a turning motor 13, and a control part. The control part acquires absolute position information of the turning shaft 5 on the basis of the output of the absolute position detector 15 to write it in a current position counter when the power supply is turned on, then changes the value of the current position counter in accordance with the rotation amount of the turning motor 13 detected by the rotation detector 17, resets the value of the current position counter when the reference position detector 16 detects that the turning shaft 5 comes to the reference position, and then changes the value of the current position counter in accordance with the rotation amount of the turning motor 13 detected by the rotation detector 17.

Description

  The present invention relates to a steer-by-wire vehicle steering apparatus that steers a steered wheel in a state where the steering wheel and the steered wheel are mechanically separated.

  As a vehicle steering device that steers a steered wheel (generally a front wheel) of a vehicle according to steering of a steering wheel by a driver, a steering motor that rotates according to steering of the steering wheel, and the steering motor A steer-by-wire system is known that has a steered shaft that moves in the axial direction with transmitted power, and changes the direction of a pair of left and right steered wheels by moving the steered shaft in the axial direction.

  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 motor is controlled based on the electrical signal. For example, according to the traveling speed of the vehicle Therefore, it is expected that the operation of the steered wheels can be changed, and that the running stability and motion performance of the vehicle can be improved.

  By the way, in the steer-by-wire vehicle steering device, the steered wheels are mechanically separated from the steering wheel so that the steering angle of the steering wheel and the steered angle of the steered wheel change correspondingly. In order to control the steering motor, it is necessary to detect the steering angle of the steering wheel and to detect the current position of the steered shaft.

  Here, in the steer-by-wire vehicle steering device, as means for detecting the position of the steered shaft, for example, those described in Patent Document 1 and those described in Patent Document 2 are known. Yes.

  In Patent Document 1, as a means for detecting the position of the steered shaft in the steer-by-wire vehicle steering apparatus, a reference position detector that detects whether or not the steered shaft is at a preset reference position; And a rotation detector for detecting the rotation amount of the steering motor.

  Then, when the power of the vehicle steering device is turned on (for example, when the ignition key of the vehicle is turned on), first, the steering motor is rotated so that the steered shaft moves to the reference position. When the reference position detector detects that the rudder shaft has come to the reference position, the rotation amount of the steering motor is continuously detected by the rotation detector, and the rotation amount of the steering motor is integrated. Thus, the current position of the steered shaft is detected. That is, in the vehicle steering apparatus of Patent Document 1, the relative position based on the rotation integration amount of the steering motor (that is, the distance corresponding to the rotation integration amount of the steering motor with respect to the reference position of the steering shaft). ) Is detected as the position of the turning shaft.

  When this configuration is adopted, the position of the steered shaft is detected based on the amount of rotation of the steered motor that rotates at a fixed position, so the position of the steered shaft is detected with high accuracy over the entire stroke of the steered shaft. It is possible.

  However, in the vehicle steering apparatus of Patent Document 1, when the power is turned on, the turning motor is rotated so that the turning shaft moves to the reference position, and the turning shaft comes to the reference position. There is a problem that it is necessary to execute an initial operation of detecting by the position detector, and the steered wheels cannot be steered until the initial operation is completed.

  On the other hand, in Patent Document 2, as a means for detecting the position of a turning shaft in a steer-by-wire vehicle steering apparatus, the absolute position is calculated without integrating the amount of rotation of the turning motor as in Patent Document 1. Is provided with an absolute position detector capable of detecting the position of the steered shaft. This absolute position detector has two resolvers provided to rotate with different electrical angles when the steered shaft moves, and a combination of electrical angle values detected by the two resolvers. Is compared with a pre-stored data table (which stores in advance the correspondence between the combination of the electrical angle values of the two resolvers and the position of the steered shaft), thereby determining the position of the steered shaft as an absolute position. It is possible to detect.

  When the position detecting means of this Patent Document 2 is adopted, the position of the steered shaft is based only on the current outputs of the two resolvers without integrating the rotation amount of the steering motor as in Patent Document 1. Therefore, when the power is turned on, there is no need to perform the initial operation as in Patent Document 1. Therefore, it is possible to steer the steered wheels by the steer-by-wire method immediately after turning on the power.

  However, when detecting the position of the steered shaft as an absolute position, it is difficult to detect the position of the steered shaft with high accuracy over the entire stroke of the steered shaft. For example, as in Patent Document 2, when the position of the steered shaft is detected as an absolute position based on the combination of the electrical angle values of two resolvers, even if there is a slight error in the electrical angle value of one of the resolvers When this occurs, the position of the steered shaft detected based on the electrical angle is greatly deviated from the actual position, so that it is difficult to detect the position of the steered shaft with stable accuracy. It is also conceivable to detect the position of the steered shaft as an absolute position using a differential transformer or linear potentiometer, but to detect the position of the steered shaft over the entire stroke of the steered shaft, a long stroke is required. It is necessary to use a differential transformer or a linear potentiometer, which is difficult from the viewpoint of installation space and manufacturing cost.

Japanese Patent No. 4165213 JP 2009-292331 A

  The problem to be solved by the present invention is that the steered wheel can be steered by the steer-by-wire method immediately after the power is turned on, and the position of the steered shaft with high accuracy over the entire stroke of the steered shaft while the vehicle is running. It is providing the vehicle steering device which can detect.

In order to solve the above-described problems, in the present invention, the following configuration is employed in the vehicle steering apparatus.
A steering motor that rotates in response to steering of the steering wheel, and a steering shaft that moves in the axial direction by power transmitted from the steering motor, and the steering shaft moves in the axial direction In the vehicle steering device that changes the direction of the pair of left and right steered wheels,
An absolute position detector that detects the position of the steered shaft as an absolute position, a reference position detector that detects whether or not the steered shaft is at a preset reference position, and rotation of the steering motor A rotation detector for detecting a quantity, and a controller having a current position counter that operates based on the absolute position detector, the reference position detector, and the output of the rotation detector;
The controller is
A first step of obtaining the absolute position information of the steered shaft based on the output of the absolute position detector when the power is turned on;
A second step of writing the absolute position information of the steered shaft acquired in the first step into a current position counter as an initial value of the current position counter;
A third step of changing the value of the current position counter according to the amount of rotation of the steering motor detected by the rotation detector after writing the initial value of the current position counter in the second step;
A fourth step of resetting the value of the current position counter to a preset reference value when the reference position detector detects that the steered shaft has reached the reference position after the power is turned on;
After resetting the value of the current position counter in the fourth step, execute a fifth step of changing the value of the current position counter according to the amount of rotation of the steering motor detected by the rotation detector. A vehicle steering apparatus configured to perform the above.

  In this way, when the power is turned on, the absolute position information of the steered shaft based on the output of the absolute position detector is written to the current position counter as the initial value of the current position counter (first step, second step). After that, the value of the current position counter changes according to the amount of rotation of the steering motor detected by the rotation detector (third step). Thus, since the value of the current position counter changes corresponding to the position of the steered shaft immediately after the power is turned on, the position of the steered shaft is determined based on the value of the current position counter immediately after the power is turned on. Can be detected. Therefore, immediately after turning on the power, the steering motor can be controlled so that the steering angle of the steering wheel and the turning angle of the steered wheels change correspondingly. Further, when the steered shaft reaches the reference position in accordance with the steering wheel for driving the vehicle, the value of the current position counter is reset to a preset reference value (fourth step) and thereafter The value of the current position counter changes with the reset reference value as an initial value (fifth step). As a result, the position of the steered shaft can be detected with high accuracy over the entire stroke of the steered shaft while the vehicle is traveling.

  The control unit includes an abnormality detection control unit that compares the output of the absolute position detector and the output of the current position counter and determines an abnormality when the difference becomes larger than a preset threshold value. Can do. In this way, when an abnormality occurs in either the absolute position detector or the rotation detector, the abnormality can be detected.

  When the control device further includes a backup clutch that can be switched between a disconnected state in which the steering wheel and the steered wheels are mechanically separated and a fastening state in which the steering wheel and the steered wheels are mechanically connected. The unit may employ a configuration including a clutch switching unit that switches the backup clutch from the disengaged state to the engaged state when the abnormality detection control unit determines that an abnormality has occurred. In this way, when an abnormality occurs in either the absolute position detector or the rotation detector, the steering wheel and the steered wheel are mechanically connected by the backup clutch, so that the vehicle is A situation in which steering becomes impossible is prevented, and the safety of the vehicle can be ensured.

  The absolute position detector includes, for example, a speed reducer that reduces and transmits the rotation of the steering motor when the turning shaft is moved with a maximum stroke to less than one rotation, and the speed reducer. A rotation angle sensor connected to the speed reducer so that the decelerated rotation can be input can be adopted. However, in this case, the absolute position of the steered shaft is caused by the backlash inside the speed reducer. The detection accuracy may be unstable.

  Therefore, the absolute position detector is in contact with the cam surface formed on the outer periphery of the steered shaft so as to have an inclination that is displaced in a direction perpendicular to the axis along the axial direction of the steered shaft. A driven body supported so as to be movable in a direction perpendicular to the turning shaft in a state, a biasing member that presses the driven body against the cam surface, and a displacement sensor that detects the displacement of the driven body. It is preferable to adopt it. In this case, since the driven body is pressed against the cam surface by the urging member, there is no backlash between the driven body and the cam surface. Therefore, it is possible to detect the absolute position of the steered shaft with stable accuracy.

The vehicle steering apparatus having the above configuration can further employ the following configuration.
A toe angle adjusting motor, a toe angle adjusting shaft that moves in the axial direction with respect to the steered shaft by power transmitted from the toe angle adjusting motor, and a position of the toe angle adjusting shaft with respect to the steered shaft And a second absolute position detector for detecting whether or not the position of the toe angle adjusting shaft relative to the steered shaft is at a preset reference position for toe angle adjustment. Reference position detector, a second rotation detector for detecting the rotation amount of the toe angle adjusting motor, the second absolute position detector, the second reference position detector, and the second rotation. And a second controller having a second current position counter that operates based on the output of the detector,
The second controller is
A first step of obtaining absolute position information of a toe angle adjusting shaft based on an output of the second absolute position detector when the power is turned on;
A second step of writing the absolute position information of the toe angle adjusting axis acquired in the first step into a second current position counter as an initial value of the second current position counter;
After the initial value of the second current position counter is written in the second step, the second current position counter is set according to the rotation amount of the toe angle adjusting motor detected by the second rotation detector. A third step of changing the value;
After the power is turned on, the second reference position detector detects that the position of the toe angle adjusting shaft relative to the steered shaft has reached the toe angle adjusting reference position. A fourth step of resetting the value of the current position counter to a preset reference value for toe angle adjustment;
After resetting the value of the second current position counter in the fourth step, the value of the second current position counter according to the rotation amount of the toe angle adjusting motor detected by the second rotation detector. And a fifth step of changing.

  In this way, when the power is turned on, the absolute position information of the toe angle adjusting shaft based on the output of the second absolute position detector is written to the second current position counter as an initial value (the first value). Then, the value of the second current position counter changes according to the rotation amount of the toe angle adjusting motor detected by the second rotation detector (third step). Thus, since the value of the second current position counter changes corresponding to the position of the toe angle adjusting shaft immediately after the power is turned on, the value of the second current position counter is immediately after the power is turned on. The position of the toe angle adjusting shaft relative to the steered shaft can be detected based on the above. Thereafter, when the toe angle adjusting shaft reaches the reference position for toe angle adjustment, the value of the second current position counter is reset to a preset reference value for toe angle adjustment (fourth step). Thereafter, the value of the second current position counter changes with the reset reference value as an initial value (fifth step). As a result, the position of the toe angle adjusting shaft can be detected with high accuracy over the entire stroke of the toe angle adjusting shaft.

  Examples of the second reference position detector include a permanent magnet fixed to the toe angle adjusting shaft, and the permanent magnet when the toe angle adjusting shaft is at the toe angle adjusting reference position. What consists of a magnetic sensor fixed to the steered shaft so as to be closest may be employed.

Moreover, in this invention, the following method is provided as a position detection method of the turning shaft for solving said subject.
A steering motor that rotates in response to steering of the steering wheel, and a steering shaft that moves in the axial direction by power transmitted from the steering motor, and the steering shaft moves in the axial direction In the method of detecting the position of the steered shaft in the vehicle steering device that changes the direction of the pair of left and right steered wheels,
An absolute position detector that detects the position of the steered shaft as an absolute position, a reference position detector that detects whether or not the steered shaft is at a preset reference position, and rotation of the steering motor A rotation detector for detecting an amount; and a current position counter that operates based on the absolute position detector, the reference position detector, and the output of the rotation detector;
A first step of obtaining the absolute position information of the steered shaft based on the output of the absolute position detector when the power is turned on;
A second step of writing the absolute position information of the steered shaft acquired in the first step into a current position counter as an initial value of the current position counter;
A third step of changing the value of the current position counter according to the amount of rotation of the steering motor detected by the rotation detector after writing the initial value of the current position counter in the second step;
A fourth step of resetting the value of the current position counter to a preset reference value when the reference position detector detects that the steered shaft has reached the reference position after the power is turned on;
After resetting the value of the current position counter in the fourth step, execute a fifth step of changing the value of the current position counter according to the amount of rotation of the steering motor detected by the rotation detector. And
A method for detecting a position of a turning shaft, wherein the value of the current position counter is detected as a position of the turning shaft.

  When this steering shaft position detection method is executed by the vehicle steering system, the absolute position information of the steered shaft based on the output of the absolute position detector is the current position counter as the initial value of the current position counter when the power is turned on. The value is written in the counter (first step, second step), and then the value of the current position counter changes according to the amount of rotation of the steering motor detected by the rotation detector (third step). Thus, since the value of the current position counter changes corresponding to the position of the steered shaft immediately after the power is turned on, the position of the steered shaft is determined based on the value of the current position counter immediately after the power is turned on. Can be detected. Therefore, immediately after turning on the power, the steering motor can be controlled so that the steering angle of the steering wheel and the turning angle of the steered wheels change correspondingly. Further, when the steered shaft reaches the reference position in accordance with the steering wheel for driving the vehicle, the value of the current position counter is reset to a preset reference value (fourth step) and thereafter The value of the current position counter changes with the reset reference value as an initial value (fifth step). As a result, the position of the steered shaft can be detected with high accuracy over the entire stroke of the steered shaft while the vehicle is traveling.

  In the vehicle steering apparatus of the present invention, when the power is turned on, the absolute position information of the steered shaft based on the output of the absolute position detector is written to the current position counter as the initial value of the current position counter, and then rotated. The value of the current position counter changes according to the rotation amount of the steering motor detected by the detector. Thus, since the value of the current position counter changes corresponding to the position of the steered shaft immediately after the power is turned on, the position of the steered shaft is determined based on the value of the current position counter immediately after the power is turned on. Can be detected. Therefore, it is possible to steer the steered wheels by the steer-by-wire method immediately after turning on the power. In addition, when the steered shaft reaches the reference position according to the steering wheel for driving the vehicle, the value of the current position counter is reset to a preset reference value, and thereafter the reset reference The value of the current position counter changes with the value as an initial value. As a result, the position of the steered shaft can be detected with high accuracy over the entire stroke of the steered shaft while the vehicle is traveling.

Schematic which shows the steering apparatus for vehicles concerning 1st Embodiment of this invention. Sectional drawing which shows the steering actuator of FIG. 1 is a block diagram showing a control system of the vehicle steering system shown in FIGS. The flowchart which shows an example of position detection control of the turning axis by the control part shown in FIG. The flowchart which shows an example of abnormality determination control by the control part shown in FIG. Sectional drawing which shows the steering actuator which replaced the absolute position detector of FIG. 2 with the other example Sectional drawing of the steering actuator of the steering apparatus for vehicles concerning 2nd Embodiment of this invention. The block diagram which shows the control system of the steering apparatus for vehicles shown in FIG. The flowchart which shows an example of the position detection control of the shaft for toe angle adjustment by the 2nd control part shown in FIG. The flowchart which shows an example of abnormality determination control by the 2nd control part shown in FIG.

  FIG. 1 shows a vehicle steering apparatus according to a first embodiment of the present invention. This vehicle steering device converts the steering angle of the steering wheel 1 by the driver into an electrical signal, and drives the steering actuator 2 based on the electrical signal to change the direction of the steered wheels 3. Is.

  The vehicle steering apparatus includes a steering wheel 1 that is steered by a driver, a reaction force actuator 4 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 according to the steering angle of the steering wheel 1. A steered actuator 2 that moves the steered shaft 5 so that the direction of the steered wheels 3 (a pair of left and right front wheels in the figure) changes, and a backup clutch 6 that switches between transmission and interruption of rotation between the steering wheel 1 and the steered actuator 2. And have.

  The reaction force actuator 4 includes a steering shaft 7 connected to the steering wheel 1 so as to rotate integrally with the steering wheel 1, and a steering angle detector 8 that detects the steering angle of the steering wheel 1 based on the rotation angle of the steering shaft 7. A reaction force motor 9 that generates a rotational torque that is a source of a steering reaction force applied to the steering wheel 1, a reduction gear 10 that amplifies the rotational torque generated by the reaction force motor 9 and transmits the amplified torque to the steering shaft 7. A steering-side connecting shaft 11 that transmits rotation input from the steering wheel 1 to the steering shaft 7 to the backup clutch 6 is provided.

  Both ends of the steered shaft 5 are connected to the steered wheels 3 via the knuckle arms 12, and when the steered shaft 5 moves in the axial direction, the direction of the pair of left and right steered wheels 3 changes in conjunction with this. It has become. Here, when the steered shaft 5 moves from one stroke end in the axial direction to the other stroke end (that is, the steered wheel 3 is steered to the left or right side at the maximum steer angle from the opposite side to the opposite side). When the steered shaft 5 is moved in the axial direction until the steering wheel is turned at the maximum turning angle), the steered shaft 5 moves in the axial direction by about 130 mm.

  The backup clutch 6 is an electromagnetic clutch that interrupts transmission of both forward and reverse rotations when energized to a coil (not shown) and transmits both forward and reverse rotations when energization of the coil is stopped. The backup clutch 6 is maintained in a disconnected state in which the steering wheel 1 and the steered wheel 3 are mechanically separated when normal, and the steering wheel 1 and the steered wheel 3 are mechanically connected when abnormal. It is switched to the fastening state.

  As shown in FIG. 2, the steered actuator 2 includes a steered motor 13, a steered shaft 5 that moves in the axial direction with power transmitted from the steered motor 13, and a rotation transmitted from the steered motor 13. Is converted into axial movement of the steered shaft 5, an absolute position detector 15 for detecting the position of the steered shaft 5 as an absolute position, and the steered shaft 5 is at a preset reference position. A reference position detector 16 for detecting whether or not, a rotation detector 17 for detecting the amount of rotation of the steering motor 13, and a steering side connecting shaft connected to the steering side connecting shaft 11 via the backup clutch 6. 18.

  The steered motor 13 is controlled to rotate in accordance with the steering of the steering wheel 1. That is, the steered motor 13 rotates so that the steered angle of the steered wheels 3 changes corresponding to the steered angle of the steering wheel 1 detected by the steering angle detector 8.

  The motion conversion mechanism 14 is a ball screw mechanism including a ball nut 20 to which rotation of the steering motor 13 is input, and a screw shaft 22 that is screw-engaged with the ball nut 20 via a ball 21. The screw shaft 22 is formed integrally with the steered shaft 5. A drive gear 24 is fixed to the motor shaft 23 of the steering motor 13. The drive gear 24 meshes with a driven gear 25 fixed to the ball nut 20, and rotation of the steering motor 13 is input to the ball nut 20 by this meshing.

  The ball nut 20 is held so as not to move in the axial direction and is rotatably supported by a bearing 26. On the other hand, the screw shaft 22 is supported so as not to rotate and to be movable in the axial direction. Therefore, when the rotation of the steering motor 13 is input to the ball nut 20, the screw shaft 22 moves in the axial direction according to the rotation of the ball nut 20, and the steered shaft 5 is integrated with the screw shaft 22. Move in the axial direction.

  The absolute position detector 15 includes a speed reducer 27 connected to the motor shaft 23 of the steering motor 13 and a rotation angle sensor 28 connected to the speed reducer 27. The reducer 27 is, for example, a planetary gear reducer or a worm gear reducer. The rotation angle sensor 28 is a sensor that detects the angle of the output shaft of the speed reducer 27 as an absolute angle. For example, the rotation angle sensor 28 is a potentiometer whose electrical resistance changes according to the angle. The speed reduction ratio of the speed reducer 27 is set to a speed reduction ratio such that the rotation of the steering motor 13 when the steered shaft 5 is moved with the maximum stroke is decelerated to less than one rotation and transmitted. . The rotation angle sensor 28 detects the position of the turning shaft 5 as an absolute position by detecting the rotation angle of rotation input after being decelerated by the speed reducer 27. That is, the rotation angle sensor 28 detects the position of the steered shaft 5 based only on the current output of the rotation angle sensor 28 without integrating the rotation amount of the steering motor 13.

  The reference position detector 16 is fixed to the casing 31 of the steered actuator 2 so as to be closest to the permanent magnet 30 when the steered shaft 5 is at the reference position. Magnetic sensor 32. The permanent magnet 30 is attached to the steered shaft 5 so that the direction perpendicular to the axis of the steered shaft 5 is a magnetization direction. The magnetic sensor 32 is disposed so as to oppose the permanent magnet 30 and the steered shaft 5 in the direction perpendicular to the axis when the steered shaft 5 is at the reference position. The magnetic sensor 32 is, for example, a Hall IC. The reference position of the steered shaft 5 is set to the position (neutral position) of the steered shaft 5 when the vehicle goes straight (that is, when the steered angle is zero). The magnetic sensor 32 is configured to output a pulse signal when the axial position of the steered shaft 5 matches the reference position.

  The rotation detector 17 is a sensor whose output signal periodically changes at every constant angle when the motor shaft 23 of the steering motor 13 is continuously rotated, and is, for example, a resolver. The resolver includes a rotor 17a that rotates integrally with the motor shaft 23, and an annular stator 17b that is provided so as to surround the rotor 17a. The stator 17b is fixed to the housing 31 of the steered actuator 2. The stator 17b 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. The amount and direction of rotation of the rotor 17a can be detected by utilizing the property that the two-phase AC voltages (A phase and B phase) change according to the rotation angle of the rotor 17a. As the rotation detector 17, an incremental encoder that outputs a pulse signal each time the motor shaft 23 rotates by a certain angle may be used.

  The backup clutch 6 mechanically disconnects the steering side connecting shaft 11 and the steered side connecting shaft 18 when energized to a coil (not shown), and when the energization to the coil is stopped, The electromagnetic clutch mechanically connects the steered side connecting shafts 18. A first bevel gear 33 is fixed to the steered side connecting shaft 18, and a second bevel gear 34 that meshes with the first bevel gear 33 is fixed to the motor shaft 23.

  The steering motor 13 and the backup clutch 6 are controlled by the control unit 40 shown in FIG. On the input side of the controller 40, an absolute position detector 15 that detects the position of the steered shaft 5 as an absolute position, a rotation detector 17 that detects the amount of rotation of the steering motor 13, and the steered shaft 5 A reference position detector 16 that detects whether or not is at the reference position and a steering angle detector 8 that detects the steering angle of the steering wheel 1 are connected.

  On the output side of the control unit 40, a steering motor 13 for moving the steered shaft 5, the backup clutch 6, and an abnormality notification unit 41 are connected. The abnormality notification unit 41 is an in-vehicle device that notifies the driver of an abnormality in the vehicle steering device, and for example, a monitor display, a steering warning light, a voice output device, or the like provided in the driver's seat can be employed.

  When the power is on, the vehicle steering device steers the steered wheels 3 with the power of the steered motor 13 in a state where the steering wheel 1 and the steered wheels 3 are mechanically disconnected. At this time, in order to control the steered motor 13 so that the steering angle of the steering wheel 1 and the steered angle of the steered wheel 3 change correspondingly, the steering angle of the steering wheel 1 is detected and steered. It is also necessary to detect the current position of the shaft 5.

  Therefore, the control unit 40 performs position detection control for detecting the current position of the steered shaft 5 when the vehicle steering device is turned on, and the current position of the steered shaft 5 detected by this position detection control. However, the steering motor 13 is controlled so as to change according to the steering angle of the steering wheel 1 detected by the steering angle detector 8. In order to perform this control, the control unit 40 has a current position counter 42 that operates based on the outputs of the absolute position detector 15, the reference position detector 16, and the rotation detector 17. The current position counter 42 changes the internal value according to the outputs of the absolute position detector 15, the reference position detector 16 and the rotation detector 17, and outputs the value as the current axial position of the steered shaft 5. Logic circuit.

  Hereinafter, an example of position detection control of the steered shaft 5 performed by the control unit 40 will be described with reference to FIG.

First, when the vehicle steering device is turned on (for example, when an ignition key of the vehicle is turned on), the control unit 40 determines the absolute position of the steered shaft 5 based on the output of the absolute position detector 15. Information is acquired (step S ₁ ), and the acquired absolute position information is written in the current position counter 42 as an initial value of the current position counter 42 (step S ₂ ).

Thereafter, when the driver steers the steering wheel 1, the steering motor 13 rotates so that the steered shaft 5 moves according to the steering angle of the steering wheel 1 detected by the steering angle detector 8. At this time, the control unit 40 detects the rotation amount and the rotation direction of the steering motor 13 detected by the rotation detector 17 until the reference position detector 16 detects that the steered shaft 5 has reached the reference position. In response to this, the value of the current position counter 42 is changed (steps S ₃ and S ₄ ). That is, when the rotation detector 17 detects forward rotation, the current position counter 42 is counted up according to the amount of rotation, and when the rotation detector 17 detects reverse rotation, The value of the current position counter 42 is counted down according to the rotation amount. Here, the value of the current position counter 42 is a relative position based on the accumulated rotation amount of the steering motor 13 (that is, an amount corresponding to the accumulated rotation amount of the steering motor 13 with respect to the reference position of the steered shaft 5). Corresponds to the position obtained by adding or subtracting the distance.

Then, when the reference position detector 16 detects that the steered shaft 5 has reached the reference position (that is, the position of the steered shaft 5 when the vehicle goes straight), the value of the current position counter 42 is set in advance. Reset to the reference value (zero in this embodiment) (steps S ₄ and S ₅ ). Thereafter, the control unit 40 changes the value of the current position counter 42 according to the rotation amount and rotation direction of the steering motor 13 detected by the rotation detector 17 (step S ₆ ).

After executing step S _5, again, when it is detected that the steering shaft 5 has come to a reference position by the reference position detector 16 each time, also possible to reset the current value of the position counter 42 to the reference value It is. However, the operation of resetting the value of the current position counter 42 to the reference value is performed only when the reference position detector 16 first detects that the steered shaft 5 has reached the reference position after the power is turned on. Thereafter, it is preferable not to reset the value of the current position counter 42 even if the reference position detector 16 detects that the steered shaft 5 has reached the reference position. In this way, it is possible to stabilize the control of the steering motor 13 when the steered shaft 5 moves across the reference position while the vehicle is traveling.

  Here, when detecting that the steered shaft 5 has reached the reference position, when the steered motor 13 is rotating in one of the preset rotational directions of the forward direction and the reverse direction, It is made not to detect that the steered shaft 5 has come to the reference position, and only when the steered motor 13 is rotating in the other rotation direction, to detect that the steered shaft 5 has come to the reference position. Then, it is possible to detect with high positional accuracy that the steered shaft 5 has come to the reference position. Further, when detecting that the turning shaft 5 has reached the reference position, if the detection is performed based on the edge of the output signal of the magnetic sensor 32 constituting the reference position detector 16, the turning shaft 5 can be detected with high positional accuracy. It is possible to detect the arrival at the reference position.

  When the vehicle steering device is turned on, the control unit 40 performs position detection control of the steered shaft 5 as described above. And the control part 40 is for steering so that the present position of the turning shaft 5 detected by this position detection control may change according to the steering angle of the steering wheel 1 detected by the steering angle detector 8. The motor 13 is controlled.

  The control unit 40 performs abnormality determination control in parallel with the above-described position detection control after the vehicle steering apparatus is powered on. The abnormality determination control is a control for detecting an abnormality when an abnormality occurs in either the absolute position detector 15 or the rotation detector 17. This abnormality determination control will be described with reference to FIG.

As shown in FIG. 5, the control unit 40 compares the output of the absolute position detector 15 with the output of the current position counter 42. That is, the absolute position information of the steered shaft 5 which is obtained based on the output of the absolute position detector 15, and the current value of the position counter 42 which changes according to the output of the rotation detector 17 compares (Step S ₁₁ ).

When the difference between the absolute position information based on the output of the absolute position detector 15 and the output value of the current position counter 42 is equal to or less than a preset threshold value, both the absolute position detector 15 and the rotation detector 17 judged to be normal (step _{S 12, S} 13). On the other hand, when the difference between the absolute position information based on the output of the absolute position detector 15 and the output value of the current position counter 42 is larger than a preset threshold value, whichever of the absolute position detector 15 and the rotation detector 17 is used. It is determined that a crab abnormality has occurred (steps S ₁₂ and S ₁₄ ).

When it is determined that an abnormality has occurred in either the absolute position detector 15 or the rotation detector 17, the abnormality notifying unit 41 is used to notify the driver of the abnormality by the abnormality notifying unit 41 shown in FIG. While operating, the power supply of the backup clutch 6 shown in FIG. 3 is stopped, and the backup clutch 6 is switched from the disconnected state to the engaged state (step S ₁₅ ).

When the vehicle steering device of this embodiment is used, when the vehicle steering device is turned on, the absolute position information of the steered shaft 5 based on the output of the absolute position detector 15 is the initial value of the current position counter 42. As the current position counter 42 (steps S ₁ and S ₂ ), and then the value of the current position counter 42 changes according to the amount of rotation of the steering motor 13 detected by the rotation detector 17 (step S). ₃ ). Thus, since the value of the current position counter 42 changes corresponding to the position of the steered shaft 5 immediately after the power is turned on, the steering is performed based on the value of the current position counter 42 immediately after the power is turned on. The position of the shaft 5 can be detected. Therefore, immediately after the power is turned on, the steering motor 13 can be controlled so that the steering angle of the steering wheel 1 and the turning angle of the steered wheels 3 change correspondingly. That is, it is possible to steer the steered wheels 3 by the steer-by-wire method immediately after turning on the power.

  By the way, it is possible to detect the position of the steered shaft 5 based only on the output of the absolute position detector 15 without using the outputs of the reference position detector 16 and the rotation detector 17 as described above. Then, it is difficult to detect the position of the steered shaft 5 with high accuracy over the entire stroke of the steered shaft 5. That is, since the rotation input from the steering motor 13 to the rotation angle sensor 28 is decelerated by the speed reducer 27, the resolution of the movement amount of the steered shaft 5 detected based on the rotation after the deceleration is low. I have to be. Further, the detection accuracy of the absolute position of the steered shaft 5 may become unstable due to the backlash inside the speed reducer 27. Further, instead of the speed reducer 27 and the rotation angle sensor 28, it is conceivable to use a differential transformer or a linear potentiometer as means for detecting the position of the steered shaft 5 as an absolute position. In order to detect the position of the steered shaft 5 over a long distance, it is necessary to use a differential transformer or a linear potentiometer having a long stroke, which is difficult from the viewpoint of installation space and manufacturing cost.

Therefore, in the vehicle steering device of this embodiment, the position of the steered shaft 5 is detected with high accuracy over the entire stroke of the steered shaft 5 during traveling of the vehicle. When 5 reaches the reference position, the value of the current position counter 42 is reset to a preset reference value (steps S ₄ and S ₅ ), and thereafter the current position counter is set with the reset reference value as an initial value. The value of 42 is changed (step S ₆ ). As a result, it is possible to detect the position of the steered shaft 5 with high accuracy over the entire stroke of the steered shaft 5 while the vehicle is traveling.

  Further, in the vehicle steering apparatus of this embodiment, the reference position of the steered shaft 5 is set to the position of the steered shaft 5 when the vehicle goes straight (that is, the neutral position where the steered angle is zero). The operation of resetting the value of the current position counter 42 to the reference value is performed at an initial stage after starting the steering of the vehicle. Therefore, even if the detection accuracy of the absolute position detector 15 is low, there is no problem in steering the vehicle, and an inexpensive sensor can be used as the absolute position detector 15.

  Moreover, in the vehicle steering apparatus of this embodiment, when an abnormality occurs in either the absolute position detector 15 or the rotation detector 17, the abnormality can be detected, and the reliability is high. Further, when an abnormality is detected, the steering wheel 1 and the steered wheel 3 are mechanically connected by the backup clutch 6, so that the vehicle cannot be steered due to an abnormality in the absolute position detector 15 or the rotation detector 17. The situation is prevented and the safety of the vehicle can be ensured.

  In the above embodiment, as the absolute position detector 15 that detects the position of the steered shaft 5 as an absolute position, the rotation of the steered motor 13 when the steered shaft 5 is moved with the maximum stroke is less than one rotation. A speed reducer 27 that decelerates and transmits the rotation and a rotation angle sensor 28 that is connected to the speed reducer 27 so that the speed reduced by the speed reducer 27 is input. However, when this absolute position detector 15 is employed, the absolute position detection accuracy of the steered shaft 5 may become unstable due to the backlash inside the speed reducer 27.

  Therefore, when the absolute position detector 15 shown in FIG. 6 is employed, the detection accuracy of the absolute position of the steered shaft 5 can be stabilized. This absolute position detector 15 is in contact with the cam surface 50 formed on the outer periphery of the steered shaft 5 so as to have an inclination that is displaced in the direction perpendicular to the axis along the axial direction of the steered shaft 5. In this state, the driven pin 51 supported so as to be movable in the direction perpendicular to the axis of the steered shaft 5, a biasing member 52 that presses the driven pin 51 against the cam surface 50, and a displacement sensor 53 that detects the displacement of the driven pin 51. It consists of.

  The cam surface 50 is formed so as to gradually become deeper from one end side in the axial direction of the steered shaft 5 toward the other end side, and the axial length of the cam surface 50 is one of the axial directions of the steered shaft 5. It is formed longer than the movement amount (in this embodiment, about 130 mm) when moved from the stroke end to the other stroke end. The inclination of the cam surface 50 is determined by the amount of movement of the driven pin 51 that moves along the inclination of the cam surface 50 when the steered shaft 5 moves from one stroke end in the axial direction to the other stroke end. (For example, about 10 mm) is set to be smaller (preferably 1/10 or less) than the amount of movement of the steered shaft 5 in the axial direction (in this embodiment, about 130 mm).

  The driven pin 51 is a sliding bearing 54 attached to the casing 31 of the steered actuator 2 so as not to move in the axial direction of the steered shaft 5, and can be advanced and retracted toward the cam surface 50 on the outer periphery of the steered shaft 5. It is supported. A roller 51 a that is in rolling contact with the cam surface 50 is provided at the front end of the driven pin 51. A spring seat 55 that receives one end of the urging member 52 is fixed to the outer periphery of the driven pin 51. The other end of the urging member 52 is supported by a slide bearing 54. The urging member 52 is, for example, a compression coil spring disposed so as to expand and contract in the direction perpendicular to the axis of the steered shaft 5.

  The displacement sensor 53 includes a permanent magnet 53a fixed to the rear end of the driven pin 51, and a magnetic sensor 53b provided so as not to move in a direction perpendicular to the axis of the steered shaft 5 at a position facing the permanent magnet 53a. . The magnetic sensor 53b is a Hall IC, for example, and is mounted on a printed circuit board 56 fixed to the casing 31 of the steered actuator 2.

  When the steered motor 13 rotates and the steered shaft 5 moves in the axial direction, the driven pin 51 moves in the direction perpendicular to the steered shaft 5 in accordance with the movement of the steered shaft 5. At this time, the permanent magnet 53a at the rear end of the driven pin 51 moves integrally with the driven pin 51, whereby the magnetic flux density penetrating the magnetic sensor 53b changes. Therefore, based on the magnetic flux density detected by the magnetic sensor 53b, the position of the steered shaft 5 can be detected as an absolute position.

  When this absolute position detector 15 is employed, the driven pin 51 is pressed against the cam surface 50 by the urging member 52, so that no play occurs between the driven body and the cam surface 50. Therefore, it is possible to detect the absolute position of the steered shaft 5 with stable accuracy.

  FIG. 7 shows a vehicle steering apparatus according to a second embodiment of the present invention. This vehicle steering device is obtained by adding a toe angle adjusting mechanism 60 to the vehicle steering device of the first embodiment. Portions corresponding to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The toe angle adjusting mechanism 60 includes a toe angle adjusting motor 61, a toe angle adjusting shaft 62 that moves in the axial direction with respect to the steered shaft 5 by the power transmitted from the toe angle adjusting motor 61, and the steered shaft 5. A second absolute position detector 63 for detecting the position of the toe angle adjusting shaft 62 as an absolute position, and a toe angle adjusting reference position in which the position of the toe angle adjusting shaft 62 with respect to the steered shaft 5 is preset. A second reference position detector 64 for detecting whether or not the motor is in the position of the motor, and a second rotation detector 65 for detecting the rotation amount of the toe angle adjusting motor 61.

  The toe angle adjusting shaft 62 is inserted into the spline nut 66 so as to be movable in the axial direction. The spline nut 66 is held so as not to move in the axial direction and is rotatably supported by a bearing 67. A spline groove 68 extending in the axial direction is formed on the outer periphery of the toe angle adjusting shaft 62. A plurality of balls 69 are incorporated between the spline groove 68 and the spline nut 66, and the toe angle adjusting shaft 62 is supported so as to be movable in the axial direction with respect to the spline nut 66 by rolling the balls 69. Further, when the spline nut 66 and the spline groove 68 are engaged with each other via the ball 69, torque is transmitted between the spline nut 66 and the toe angle adjusting shaft 62, and the toe angle adjusting shaft 62 is connected to the spline nut. 66 and rotate together.

  A drive gear 71 is fixed to the motor shaft 70 of the toe angle adjusting motor 61. The drive gear 71 is engaged with a driven gear 72 fixed to the spline nut 66, and the rotation of the toe angle adjusting motor 61 is input to the spline nut 66 by this engagement. The toe angle adjusting shaft 62 is arranged coaxially with the steered shaft 5. A female screw 73 is formed at one end of the toe angle adjusting shaft 62, and a male screw 74 formed at one end of the steered shaft 5 is screw-engaged with the female screw 73.

  When the toe angle adjusting motor 61 is rotated, the rotation of the toe angle adjusting motor 61 is transmitted to the spline nut 66 through the drive gear 71 and the driven gear 72 in this order. When the spline nut 66 rotates, the male screw 74 and the female screw 73 rotate relative to each other, thereby changing the screwing depth of the male screw 74 and the female screw 73. As a result, the toe angle adjusting shaft 62 moves in the axial direction, and the steered wheels The toe angle of 3 changes.

  When the toe angle adjusting motor 61 is rotated, of the pair of left and right steered wheels 3 (that is, the steered wheel 3 on the toe angle adjusting shaft 62 side and the steered wheel 3 on the steered shaft 5 side), the toe angle adjusting shaft The toe angle of only the steered wheel 3 on the 62 side changes. In order to adjust the toe angle of the opposite steered wheel 3 as well, by rotating both the steered motor 13 and the toe angle adjusting motor 61, the axial position of the toe angle adjusting shaft 62 and the steered wheel are rotated. 3 and the axial direction position are respectively changed. In this way, toe-in and toe-out can be adjusted.

  The second absolute position detector 63 includes a speed reducer 75 connected to the motor shaft 70 of the toe angle adjusting motor 61 and a rotation angle sensor 76 connected to the speed reducer 75. The rotation angle sensor 76 is a sensor that detects the angle of the output shaft of the speed reducer 75 as an absolute angle, and is, for example, a potentiometer whose electrical resistance changes in accordance with the angle. The reduction ratio of the reduction gear 75 is set to such a reduction ratio that the rotation of the toe angle adjusting motor 61 when the toe angle adjusting shaft 62 is moved with the maximum stroke is reduced to less than one rotation and transmitted. Has been. The rotation angle sensor 76 detects the position of the toe angle adjusting shaft 62 with respect to the steered shaft 5 as an absolute position by detecting the rotation angle of rotation input after being decelerated by the speed reducer 75. That is, the rotation angle sensor 76 does not integrate the rotation amount of the toe angle adjusting motor 61, and determines the position of the toe angle adjusting shaft 62 relative to the steered shaft 5 based only on the current output of the rotation angle sensor 76. To detect.

  The second reference position detector 64 is closest to the permanent magnet 77 when the toe angle adjusting shaft 62 is in the reference position for toe angle adjustment, and the permanent magnet 77 fixed to the toe angle adjusting shaft 62. Thus, the magnetic sensor 79 is fixed to the steered shaft 5 via the arm 78. The permanent magnet 77 has a ring shape extending in the circumferential direction along the outer periphery of the toe angle adjusting shaft 62 in order to prevent the rotation of the toe angle adjusting shaft 62 from affecting the output of the magnetic sensor 79. Further, the permanent magnet 77 is a magnet that is radially magnetized so that the inner peripheral surface and the outer peripheral surface each have a single magnetic pole (N pole or S pole). The magnetic sensor 79 is disposed so as to face the outer diameter side of the permanent magnet 77 when the toe angle adjusting shaft 62 is at the reference position. The magnetic sensor 79 is, for example, a Hall IC. The reference position of the toe angle adjusting shaft 62 is set to the position of the toe angle adjusting shaft 62 when the toe angle is zero (that is, the neutral position). The magnetic sensor 79 is configured to output a pulse signal when the position of the toe angle adjusting shaft 62 in the axial direction matches the reference position.

  The second rotation detector 65 is a sensor whose output signal periodically changes at every constant angle when the motor shaft 70 of the toe angle adjusting motor 61 continuously rotates, and is, for example, a resolver. The resolver includes a rotor 65a that rotates integrally with the motor shaft 70, and an annular stator 65b that is provided so as to surround the rotor 65a. The stator 65 b is fixed to the housing 31 of the steering actuator 2. The stator 65b 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 amount and direction of rotation of the rotor 65a by utilizing the property that the two-phase AC voltage (A phase, B phase) changes according to the rotation angle of the rotor 65a. As the second rotation detector 65, an incremental encoder that outputs a pulse signal each time the motor shaft 70 rotates by a certain angle may be used.

  The toe angle adjusting motor 61 is controlled by the second control unit 80 shown in FIG. On the input side of the second control unit 80, the second absolute position detector 63 that detects the position of the toe angle adjusting shaft 62 with respect to the steered shaft 5 as an absolute position, and the rotation amount of the toe angle adjusting motor 61 And a second reference position for detecting whether or not the position of the toe angle adjusting shaft 62 relative to the steered shaft 5 is at a preset toe angle adjusting reference position. A detector 64 is connected.

  On the output side of the second control unit 80, a toe angle adjusting motor 61 for moving the toe angle adjusting shaft 62 with respect to the steered shaft 5 and an abnormality notifying unit 41 are connected.

  The second control unit 80 performs position detection control for detecting the current position of the toe angle adjusting shaft 62 when the vehicle steering apparatus is powered on. In order to perform this control, the second control unit 80 operates based on the outputs of the second absolute position detector 63, the second reference position detector 64, and the second rotation detector 65. Current position counter 81. The second current position counter 81 changes the internal value in accordance with the outputs of the second absolute position detector 63, the second reference position detector 64, and the second rotation detector 65, This is a logic circuit that outputs the current axial position of the toe angle adjusting shaft 62.

  Hereinafter, an example of position detection control of the toe angle adjusting shaft 62 performed by the second control unit 80 will be described with reference to FIG.

First, when the power of the vehicle steering device is turned on (for example, when the ignition key of the vehicle is turned on), the second control unit 80 determines the toe based on the output of the second absolute position detector 63. The absolute position information of the angle adjusting shaft 62 is acquired (step S ₂₁ ), and the acquired absolute position information is written in the second current position counter 81 as an initial value of the second current position counter 81 (step S _22). ).

Thereafter, when the vehicle starts traveling, the toe angle adjusting motor 61 rotates so that the toe angle adjusting shaft 62 moves in the axial direction according to the traveling state of the vehicle. At this time, the second control unit 80 performs the second rotation detector until the second reference position detector 64 detects that the toe angle adjusting shaft 62 has reached the toe angle adjusting reference position. The value of the second current position counter 81 is changed in accordance with the rotation amount and rotation direction of the toe angle adjusting motor 61 detected at 65 (steps S ₂₃ and S ₂₄ ). That is, when the second rotation detector 65 detects forward rotation, the second current position counter 81 counts up according to the amount of rotation, and the second rotation detector 65 reverses the direction. Is detected, the value of the second current position counter 81 is counted down according to the amount of rotation. Here, the value of the second current position counter 81 is a relative position based on the rotation integration amount of the toe angle adjusting motor 61 (that is, the toe angle adjusting motor 61 has a reference position of the toe angle adjusting shaft 62). This corresponds to the position obtained by adding or subtracting the distance corresponding to the accumulated rotation amount).

The second reference position detector detects that the toe angle adjusting shaft 62 has reached the reference position for toe angle adjustment (that is, the position of the toe angle adjusting shaft 62 when the toe angle of the steered wheels 3 becomes zero). If it is detected at 64, the value of the second current position counter 81 is reset to a preset reference value (zero in this embodiment) (steps S ₂₄ and S ₂₅ ). Thereafter, the second control unit 80 changes the value of the second current position counter 81 in accordance with the rotation amount and the rotation direction of the toe angle adjusting motor 61 detected by the second rotation detector 65 (Step S80). S _26).

  When the vehicle steering apparatus is turned on, the second control unit 80 performs position detection control of the toe angle adjusting shaft 62 as described above. Then, the second control unit 80 adjusts the toe angle so that the current position of the toe angle adjusting shaft 62 detected by the position detection control moves to a position set in advance according to the traveling state of the vehicle. The motor 61 is controlled.

  The second control unit 80 performs abnormality determination control in parallel with position detection control of the toe angle adjusting shaft 62 after the vehicle steering apparatus is powered on. The abnormality determination control is a control for detecting an abnormality when any one of the second absolute position detector 63 and the second rotation detector 65 is abnormal. This abnormality determination control will be described with reference to FIG.

As shown in FIG. 10, the second control unit 80 compares the output of the second absolute position detector 63 with the output of the second current position counter 81. That is, the absolute current position information of the toe angle adjusting shaft 62 acquired based on the output of the second absolute position detector 63 and the second current position counter that changes in accordance with the output of the second rotation detector 65. The value 81 is compared (step S ₃₁ ).

When the difference between the absolute position information based on the output of the second absolute position detector 63 and the output value of the second current position counter 81 is equal to or less than a preset second threshold value, the second absolute It is determined that both the position detector 63 and the second rotation detector 65 are normal (steps S ₃₂ and S ₃₃ ). On the other hand, when the difference between the absolute position information based on the output of the second absolute position detector 63 and the output value of the second current position counter 81 is larger than a preset second threshold, It is determined that an abnormality has occurred in either the absolute position detector 63 or the second rotation detector 65 (steps S ₃₂ and S ₃₄ ).

When it is determined that an abnormality has occurred in either the second absolute position detector 63 or the second rotation detector 65, the abnormality notification unit 41 shown in FIG. 8 notifies the driver of the abnormality. Then, the abnormality notifying unit 41 is operated (step S ₃₅ ). At this time, the toe angle adjustment control may be stopped. Here, since the toe angle adjustment range by the toe angle adjusting mechanism 60 is usually as small as about ± 2 degrees, it is determined that an abnormality has occurred in either the second absolute position detector 63 or the second rotation detector 65. Even when this is done, the backup clutch 6 may not be fastened.

When the vehicle steering apparatus of the second embodiment is used, the absolute position information of the toe angle adjusting shaft 62 based on the output of the second absolute position detector 63 is obtained when the vehicle steering apparatus is turned on. 2 as an initial value (steps S ₂₁ and S ₂₂ ), and then the second current position counter 81 according to the rotation amount of the toe angle adjusting motor 61 detected by the second rotation detector 65. The value of the position counter 81 changes (step S ₃₃ ). Thus, since the value of the second current position counter 81 changes corresponding to the position of the toe angle adjusting shaft 62 immediately after the power is turned on, the second current position counter 81 is turned on immediately after the power is turned on. Based on the value of 81, the position of the toe angle adjusting shaft 62 with respect to the steered shaft 5 can be detected. Thereafter, when the toe angle adjusting shaft 62 reaches the reference position for toe angle adjustment, the value of the second current position counter 81 is reset to a preset reference value for toe angle adjustment (step S ₂₄ , S _25), thereafter, the value of the second current position counter 81 changes the reset reference value as an initial value (step S _26). Thereby, during traveling of the vehicle, the position of the toe angle adjusting shaft 62 can be detected with high accuracy over the entire stroke of the toe angle adjusting shaft 62.

  Further, the vehicle steering apparatus according to the second embodiment can detect an abnormality when an abnormality occurs in one of the second absolute position detector 63 and the second rotation detector 65. High reliability.

  In each of the above-described embodiments, the vehicle steering device employing a ball screw mechanism as an example of the motion conversion mechanism 14 that converts the rotation transmitted from the steering motor 13 into the axial movement of the steering shaft 5 has been described. However, instead of the ball screw mechanism, a sliding screw mechanism without the ball 21 may be adopted. Further, instead of the ball screw mechanism, a rack and pinion mechanism including a pinion to which rotation of the steering motor 13 is input and a rack integrally formed with the steering shaft 5 so as to mesh with the pinion is adopted. Is also possible. In this case, a reduction gear that decelerates the rotation of the steering motor 13 and transmits it to the rack and pinion mechanism can be incorporated between the steering motor 13 and the rack and pinion mechanism.

  Moreover, in each said embodiment, the backup clutch which can switch between the isolation | separation state which disconnected mechanically between the steering wheel 1 and the steered wheel 3, and the state which connected between the steering wheel 1 and the steered wheel 3 mechanically. Although the vehicle steering apparatus provided with 6 has been described as an example, the present invention is directed to a vehicle steering apparatus in which the backup clutch 6 does not exist (that is, the steering wheel 1 and the steered wheels 3 are always disconnected). May also be applied.

  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 3 Steering wheel 5 Steering shaft 6 Backup clutch 13 Steering motor 15 Absolute position detector 16 Reference position detector 17 Rotation detector 27 Reduction gear 28 Rotation angle sensor 40 Control part 42 Current position counter 50 Cam surface 51 Follower pin 52 Biasing member 53 Displacement sensor 61 Toe angle adjustment motor 62 Toe angle adjustment shaft 63 Second absolute position detector 64 Second reference position detector 65 Second rotation detector 77 Permanent magnet 79 Magnetic sensor 80 Second control unit 81 Second current position counter

Claims (8)

A steering motor (13) that rotates in response to steering of the steering wheel (1), and a steering shaft (5) that moves in the axial direction by power transmitted from the steering motor (13); In the vehicle steering apparatus for changing the direction of the pair of left and right steered wheels (3) by moving the steered shaft (5) in the axial direction,
An absolute position detector (15) for detecting the position of the steered shaft (5) as an absolute position, and a reference position detector for detecting whether the steered shaft (5) is at a preset reference position. (16), a rotation detector (17) for detecting the amount of rotation of the steering motor (13), the absolute position detector (15), the reference position detector (16), and the rotation detector ( And a control unit (40) having a current position counter (42) that operates based on the output of (17),
The control unit (40)
A first step (S ₁ ) for obtaining absolute position information of the steered shaft (5) based on the output of the absolute position detector (15) when the power is turned on;
A second step (S ₂ ) of writing the absolute position information of the steered shaft (5) acquired in the _first step (S ₁ ) into the current position counter (42) as an initial value of the current position counter (42). )When,
After the initial value of the current position counter (42) is written in the second step (S ₂ ), the current value is determined according to the amount of rotation of the steering motor (13) detected by the rotation detector (17). A third step (S ₃ ) for changing the value of the position counter (42);
When the reference position detector (16) detects that the steered shaft (5) has reached the reference position after the power is turned on, the value of the current position counter (42) is set to a preset reference value. A fourth step (S ₄ , S ₅ ) to reset to
After resetting the values of the fourth step (S _{4, S 5)} at the current position counter (42), according to the amount of rotation of the steering motor (13) detected by the rotation detector (17) A vehicle steering apparatus configured to execute a fifth step (S ₆ ) for changing a value of the current position counter (42). The control unit (40) compares the output of the absolute position detector (15) with the output of the current position counter (42), and when the difference becomes larger than a preset threshold value, The vehicle steering apparatus according to claim 1, further comprising an abnormality detection control means for determining (S ₁₁ , S ₁₂ , S ₁₄ ). Between the separated state in which the steering wheel (1) and the steered wheel (3) are mechanically separated from each other, and the fastening state in which the steering wheel (1) and the steered wheel (3) are mechanically connected. The switchable backup clutch (6) is further provided,
Wherein the control unit (40), the abnormality detection control means _{(S 11, S 12, S} 14) in abnormal judgment the clutch switching means for switching from a state disconnecting the backup clutch (6) to the fastening state when the _{(S 15} The vehicle steering apparatus according to claim 2, further comprising:   The absolute position detector (15) has a cam surface formed on the outer periphery of the steered shaft (5) so as to have an inclination that is displaced in a direction perpendicular to the axis along the axial direction of the steered shaft (5). 50), a follower (51) supported so as to be movable in a direction perpendicular to the axis of the steered shaft (5) in contact with the cam surface (50), and the follower (51) as the cam surface The vehicle steering apparatus according to any one of claims 1 to 3, comprising an urging member (52) that is pressed against (50) and a displacement sensor (53) that detects a displacement of the driven body (51).   The absolute position detector (15) decelerates and transmits the rotation of the steering motor (13) to less than one rotation when the steered shaft (5) is moved with the maximum stroke. A rotation angle sensor (28) connected to the speed reducer (27) so that rotation decelerated by the speed reducer (27) is input. The steering apparatus for vehicles as described. A toe angle adjusting motor (61), a toe angle adjusting shaft (62) that moves in the axial direction with respect to the steered shaft (5) by power transmitted from the toe angle adjusting motor (61), and A second absolute position detector (63) for detecting the position of the toe angle adjusting shaft (62) with respect to the steered shaft (5) as an absolute position, and the toe angle adjusting shaft with respect to the steered shaft (5) The rotation amount of the second reference position detector (64) for detecting whether or not the position of (62) is at a preset reference position for toe angle adjustment and the toe angle adjustment motor (61) is determined. A second rotation detector (65) for detecting, an output of the second absolute position detector (63), the second reference position detector (64), and the second rotation detector (65); A second control unit (80) having a second current position counter (81) that operates based on And,
The second control unit (80)
A first step (S ₂₁ ) of obtaining absolute position information of the toe angle adjusting shaft (62) based on the output of the second absolute position detector (63) when the power is turned on;
The absolute position information of said first step toe angle adjusting shaft obtained in (S ₂₁₎ (62), said second current second current position counter as the initial value of the position counter (81) (81) A second step of writing (S ₂₂ );
After writing the initial value of the second step the second current position counter (81) with (S _22), the second toe angle adjusting motor detected by the rotation detector (65) (61) A third step (S ₂₃ ) for changing the value of the second current position counter (81) in accordance with the amount of rotation;
After the power is turned on, the second reference position detector (64) indicates that the position of the toe angle adjusting shaft (62) relative to the steered shaft (5) has reached the reference position for toe angle adjustment. A fourth step (S ₂₄ , S ₂₅ ) that, when detected, resets the value of the second current position counter (81) to a preset reference value for toe angle adjustment;
The fourth step _{(S 24, S 25)} after resetting the second value of the current position counter (81), the second toe angle adjusting motor detected by the rotation detector (65) (61 The fifth step (S ₂₆ ) is performed to change the value of the second current position counter (81) in accordance with the amount of rotation of the second current position counter (81). Vehicle steering system.   The second reference position detector (64) includes a permanent magnet (77) fixed to the toe angle adjusting shaft (62) and the toe angle adjusting shaft (62) serving as a reference for adjusting the toe angle. The vehicle steering apparatus according to claim 6, comprising a magnetic sensor (79) fixed to the steered shaft (5) so as to be closest to the permanent magnet (77) when in position. A steering motor (13) that rotates in response to steering of the steering wheel (1), and a steering shaft (5) that moves in the axial direction by power transmitted from the steering motor (13); In the method of detecting the position of the steered shaft in the vehicle steering device for changing the direction of the pair of left and right steered wheels (3) by moving the steered shaft (5) in the axial direction,
An absolute position detector (15) for detecting the position of the steered shaft (5) as an absolute position, and a reference position detector for detecting whether the steered shaft (5) is at a preset reference position. (16), a rotation detector (17) for detecting the amount of rotation of the steering motor (13), the absolute position detector (15), the reference position detector (16), and the rotation detector ( 17) and a current position counter (42) that operates based on the output of
A first step (S ₁ ) for obtaining absolute position information of the steered shaft (5) based on the output of the absolute position detector (15) when the power is turned on;
A second step (S ₂ ) of writing the absolute position information of the steered shaft (5) acquired in the _first step (S ₁ ) into the current position counter (42) as an initial value of the current position counter (42). )When,
After the initial value of the current position counter (42) is written in the second step (S ₂ ), the current value is determined according to the amount of rotation of the steering motor (13) detected by the rotation detector (17). A third step (S ₃ ) for changing the value of the position counter (42);
When the reference position detector (16) detects that the steered shaft (5) has reached the reference position after the power is turned on, the value of the current position counter (42) is set to a preset reference value. A fourth step (S ₄ , S ₅ ) to reset to
After resetting the values of the fourth step (S _{4, S 5)} at the current position counter (42), according to the amount of rotation of the steering motor (13) detected by the rotation detector (17) And a fifth step (S ₆ ) for changing the value of the current position counter (42),
A method for detecting a position of a steered shaft, wherein the value of the current position counter (42) is detected as the position of the steered shaft (5).

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