JP2013095353A - Vehicle steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle steering device for securing sufficient vehicular motion when a steer-by-wire device fails.SOLUTION: This vehicle steering device 10 for a vehicle 1 including a first wheel 2 turned by a steer-by-wire device 12, and second wheels 3 turned by mechanical connection with an operation member 5 for a driver includes a rotary shaft 32 connected to the operation member 5 to be rotatable by input to the operation member 5, and a rotation angle restraining mechanism 34 for limiting a rotatable range of the rotary shaft 32. The rotation angle restraining mechanism 34 is structured to permit rotation exceeding the rotatable range to the rotary shaft 32 when the steer-by-wire device 12 fails.

Description

  The present invention relates to a vehicle steering apparatus.

  A four-wheel steering device that controls the toe angle of a rear wheel in order to improve the turning performance of the vehicle is known (see, for example, Patent Document 1). Further, there is known a steer-by-wire type vehicle steering apparatus in which a rotating shaft connected to an operation member and a steering mechanism for turning a wheel can be connected by an electromagnetic clutch and can be released (for example, a patent) Reference 2).

  There is known a steer-by-wire type power steering device for industrial vehicles such as a forklift that cannot operate a handle when the power is turned off (see, for example, Patent Document 3). It is also known to use a steering reaction force motor to limit the steering angle of the steering wheel (see, for example, Patent Document 4).

JP 2008-201173 A JP 2009-67131 A JP 2010-70083 A JP 2011-116214 A

  In a steer-by-wire type vehicle, it is desirable to take appropriate fail countermeasures so that the vehicle can turn right and left even when the steer-by-wire system fails. Typically, for this purpose, electrical system multiplexing and mechanical backup systems are employed. By multiplexing the electric system, even if an abnormality occurs in one system, normal steering can be continued by another system. In the mechanical backup system, an operation member and a steered wheel that are not usually coupled are coupled in the event of an electrical failure so that the wheel can be steered.

  However, there is a problem with such fail countermeasures. For example, cost is required for equipment for countermeasures, which often results in a significant cost increase. It is also necessary to secure a space for mounting the equipment. Further, when a mechanical backup system is provided, the operation member and the steered wheels are ultimately configured to be mechanically connectable. The original advantage of steer-by-wire, which is to improve the degree of freedom of the mounting location due to mechanical disconnection, cannot always be utilized.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle steering apparatus for ensuring sufficient vehicle motion at the time of failure of the steer-by-wire apparatus.

  In order to solve the above-described problem, a vehicle steering apparatus according to an aspect of the present invention is a second steering apparatus that is steered by mechanical connection between a first wheel that is steered by a steer-by-wire apparatus and an operation member for a driver. A vehicle steering apparatus for a vehicle comprising: the vehicle wheel, wherein the vehicle steering apparatus is configured to steer the first wheel and the second wheel by an input to the operation member. . The vehicle steering apparatus includes a rotation shaft that is coupled to the operation member so as to be rotatable by the input, and the operation member transmits the input to the second wheel regardless of an operating state of the steer-by-wire apparatus. And an operation force transmission mechanism that mechanically connects the second wheel and a rotation angle suppression mechanism for limiting a rotatable range of the rotation shaft. The rotation angle suppression mechanism is configured to allow the rotation shaft to rotate beyond the rotatable range when the steer-by-wire device fails.

  According to this aspect, the vehicle steering device steers the first wheel by the steer-by-wire device and turns the second wheel by mechanical connection with the operation member in accordance with the input to the operation member. In normal times, the vehicle steering device can ensure sufficient vehicle motion including right and left turn of the vehicle by turning the first and second wheels.

  The rotatable range of the rotary shaft connected to the operation member is usually limited by a rotation angle suppression mechanism. This rotating shaft constitutes a part of an operating force transmission mechanism for mechanically connecting the operating member and the second wheel steered by the operation. On the other hand, when the steer-by-wire device for the first wheel fails, the rotating shaft is allowed to rotate beyond the limited rotatable range.

  Therefore, the operation range of the operation member is expanded at the time of failure. The steered angle range of the second wheel increases with the expansion. This is because the second wheel is mechanically connected to the operating member by the operating force transmission mechanism regardless of the operating state of the steer-by-wire device. In this way, by shifting the shaft foot to the turning by the second wheel at the time of failure, it becomes possible to ensure sufficient vehicle movement as in the normal time.

  Further, it is possible to implement a failure countermeasure while suppressing the addition of devices. For example, sufficient vehicle motion can be ensured during a failure by expanding the steering angle range of the second wheel without providing an additional mechanical backup system between the first wheel and the steer-by-wire device. Can do.

  The turning angle of the second wheel corresponding to the rotatable range may be set to be smaller than the turning angle of the first wheel by the steer-by-wire device.

  In this case, the first wheel steered by the steer-by-wire device steers larger than the second wheel steered by mechanical connection with the operation member. That is, normally, steer-by-wire mainly contributes to steering of the vehicle, and steering by mechanical connection is auxiliary. Therefore, the advantage of steer-by-wire can be utilized without being greatly affected by mechanical constraints. For example, normally good steering performance can be provided by control.

  The rotation angle suppression mechanism may be configured to release the limitation of the rotatable range by stopping energization, and the steer-by-wire device may stop energization to the rotation angle suppression mechanism during the failure.

  If it does in this way, it will become possible to cancel certainly the restriction of the rotatable range by a rotation angle control mechanism at the time of failure of a steer-by-wire device.

  The rotation angle suppression mechanism is configured to apply a reaction force for restricting the rotation of the rotation shaft to the rotation shaft by energization, and to release the reaction force by stopping the energization, and the steer-by-wire device includes: Energization of the rotation angle suppression mechanism may be stopped during the failure.

  If it does in this way, it will become possible to cancel | release reliably the reaction force for the rotation limitation by a rotation angle suppression mechanism at the time of failure of a steer-by-wire apparatus.

  Another aspect of the present invention is a vehicle steering device for a vehicle including a wheel that is steered by a steer-by-wire device and a wheel that is steered by mechanical connection with an operation member for a driver. The vehicle steering apparatus includes a rotation shaft that is rotatably connected to the operation member by an input to the operation member, and a rotation angle suppression mechanism that limits a rotatable range of the rotation shaft. The rotation angle suppression mechanism is configured to allow the rotation shaft to rotate beyond the rotatable range when the steer-by-wire device fails.

  According to this aspect, the rotatable range of the rotating shaft connected to the operation member is normally limited by the rotation angle suppression mechanism. When the steer-by-wire device fails, the rotation shaft is allowed to rotate beyond the limited rotatable range. Therefore, the operation range of the operation member is expanded at the time of failure. In accordance with the enlargement, the turning angle range of the wheels to be turned by mechanical connection with the operation member also increases. Therefore, sufficient vehicle movement can be ensured even during a failure.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle steering apparatus for ensuring sufficient motion of a vehicle at the time of a failure of a steer-by-wire apparatus is provided.

1 is a diagram showing a schematic configuration of a vehicle steering apparatus according to an embodiment of the present invention. It is sectional drawing which shows the rotation angle suppression mechanism which concerns on this Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate.

  FIG. 1 is a diagram showing a schematic configuration of a vehicle steering apparatus 10 according to an embodiment of the present invention. The vehicle steering device 10 is provided in the vehicle 1. The vehicle 1 includes a plurality of wheels including a first wheel 2 and a second wheel 3 different from the first wheel 2. The first wheel 2 is, for example, one rear wheel, and the second wheel 3 is, for example, two front wheels (a right front wheel and a left front wheel).

  Note that the arrangement and number of wheels in the vehicle 1 are not necessarily limited to those in the present embodiment. For example, the first wheel 2 may be one or two front wheels or rear wheels, for example. Similarly, the second wheel 3 may be, for example, one or two front wheels or rear wheels. The first wheel 2 may be one of the front wheels (or the rear wheels) and the second wheel 3 may be the other one of the front wheels (or the rear wheels). As long as the context allows, the first wheel 2 and the second wheel 3 may point to the same wheel.

  The vehicle 1 also includes a vehicle body 4 and an operation member 5 for the driver. Typically, the operation member 5 is, for example, a steering wheel that is rotated by a driver, and is fixed to the vehicle body 4, for example, to the reinforcement of the instrument panel.

  The vehicle steering device 10 is configured to steer the first wheel 2 and the second wheel 3 by an input to the operation member 5 by the driver. The vehicle steering device 10 includes a steer-by-wire device 12 and an operating force transmission mechanism 14. The steer-by-wire device 12 is configured to steer the first wheel 2 based on an input to the operation member 5. The operation force transmission mechanism 14 is configured to steer the second wheel 3 by mechanically transmitting the input to the operation member 5 to the second wheel 3.

  When the steer-by-wire device 12 is operating normally, the operable range of the operation member 5 (for example, the rotatable range of the steering wheel) is limited by the rotation angle suppression mechanism 34, as will be described later. Thus, the turning angle of the second wheel 3 corresponding to the restricted operable range of the operating member 5 is set to be smaller than the turning angle of the first wheel 2 by the steer-by-wire device 12. . That is, normally, for the steering of the vehicle 1, the first wheel 2 functions as a main steering wheel and the second wheel 3 functions as an auxiliary steering wheel.

  The steer-by-wire device 12 converts an operation input into an electric signal, generates a control signal from the electric signal, and controls an actuator for steering the vehicle 1 by the control signal. In this way, the steering of the vehicle 1 according to the operation input is electrically realized without using mechanical connection.

  For this purpose, the steer-by-wire device 12 includes a steering unit 16, a steered unit 18, and a control unit 20. The steering unit 16 includes the operation member 5. The steering unit 16 and the steered unit 18 are mechanically separated. The control unit 20 controls the steering unit 18 based on the input from the steering unit 16. The steer-by-wire device 12 steers the first wheel 2 with the power generated by the steered portion 18, regardless of the operating force applied to the operating member 5 under the control of the control unit 20.

  In the present embodiment, the steer-by-wire device 12 is not provided with a connection mechanism that mechanically connects the steering unit 16 and the steered unit 18. However, the steer-by-wire device 12 may include a connection mechanism that mechanically connects the steering unit 16 and the steered unit 18. Such a coupling mechanism may be used as a mechanical backup system when the steer-by-wire device 12 fails.

  The steering unit 16 includes an operation amount sensor 22 for measuring the operation amount of the operation member 5. The operation amount of the operation member 5 is, for example, the steering angle or the rotation angle of the steering wheel, and the operation amount sensor 22 is, for example, a steering angle sensor. The operation amount sensor 22 may measure the rotation angle of the rotation shaft 32 connected to the operation member 5. The measurement result of the operation amount sensor 22 is output to the control unit 20. Therefore, the operation amount sensor 22 and the control unit 20 are connected so as to communicate with each other.

  The steered portion 18 includes a steered motor 24 as a power source for steering the first wheel 2. The steered motor 24 steers the first wheel 2 based on a control command from the control unit 20. The steered motor 24 may be coupled to the first wheel 2 so as to directly drive the first wheel 2. Alternatively, the steering motor 24 may be coupled to the first wheel 2 so as to drive the first wheel 2 via a power transmission mechanism.

  The steered portion 18 includes a steered angle sensor 26 for measuring the steered angle of the first wheel 2. The turning angle sensor 26 does not necessarily measure the turning angle directly, and is configured to measure the displacement amount of the first wheel 2 for calculating the turning angle of the first wheel 2. It may be. The measurement result of the turning angle sensor 26 is output to the control unit 20. Therefore, the turning angle sensor 26 and the control unit 20 are connected so as to communicate with each other. The control unit 20 may perform feedback control based on the output of the turning angle sensor 26 so that the turning angle of the first wheel 2 follows the command value.

  The control unit 20 includes a steering electronic control unit (hereinafter simply referred to as ECU) 28. The ECU 28 includes a driver such as a computer, various motors, and various actuators. For example, the ECU 28 receives a signal related to the operation amount of the operation member 5 and a signal related to the turning angle of the first wheel 2. A signal related to the operation amount of the operation member 5 is transmitted from the operation amount sensor 22 to the ECU 28. A signal related to the turning angle of the first wheel 2 is transmitted from the turning angle sensor 26 to the ECU 28. Based on these signals, the ECU 28 determines a control command for the steered motor 24 and transmits it to the steered motor 24 so that the vehicle 1 is steered according to the operation amount of the operating member 5.

  The ECU 28 may control the turning angle by changing the turning angle corresponding to a certain operation amount according to the vehicle speed (or other conditions). For this purpose, the vehicle 1 is provided with a wheel speed sensor (not shown) for detecting the wheel rotation speed on at least one wheel, and the ECU 28 is configured to obtain the vehicle body speed from the detection result of the wheel speed sensor. It may be.

  The steer-by-wire device 12 may be configured to provide so-called vehicle speed sensitive steering. That is, the steer-by-wire device 12 may make the steering operation heavy when the vehicle body speed is high. Therefore, a reaction force generation motor (not shown) for generating an operation reaction force may be connected to the operation member 5, or a power steering device (not shown) provided in the operation force transmission mechanism 14. May be used. The ECU 28 may adjust the operation reaction force according to the vehicle body speed by controlling a reaction force applying motor or the like based on the obtained vehicle body speed.

  In addition, the control unit 20 includes a battery 30. The battery 30 is a power source for the steer-by-wire device 12. The steer-by-wire device 12 is activated by the power supply from the battery 30. In the present embodiment, the battery 30 is not a dedicated power source for the steer-by-wire device 12 but also a power source for a rotation angle suppression mechanism 34 described later. The battery 30 may be a power source for the vehicle 1, and in that case, the battery 30 may not be regarded as a component of the steer-by-wire device 12.

  The operating force transmission mechanism 14 mechanically connects the operating member 5 and the second wheel 3 so as to transmit the input of the operating member 5 to the second wheel 3 regardless of the operating state of the steer-by-wire device 12. In other words, the operating force transmission mechanism 14 is a mechanism that mechanically always connects the operating member 5 and the second wheel 3.

  The operating force transmission mechanism 14 includes a rotating shaft 32 that is connected to the operating member 5 so as to be rotatable by an input to the operating member 5. The rotating shaft 32 is, for example, a steering shaft that couples the operation member 5 to the steering gear box 36. The operation member 5 and the rotating shaft 32 are attached so as not to rotate relative to each other. Therefore, the rotation shaft 32 rotates integrally with the operation member 5 by the rotation operation of the operation member 5.

  The operating force transmission mechanism 14 includes a steering gear box 36 that converts the rotation of the rotary shaft 32 into a left and right linear motion. The steering gear box 36 includes, for example, a pinion gear fixed to the tip of the rotary shaft 32 and a rack that meshes with the pinion gear. The rack is connected to the left and right tie rods. The left and right tie rods are connected to the second wheel 3 via left and right knuckle arms, respectively.

  A rotation angle suppression mechanism 34 is provided in the middle of the rotation shaft 32. The rotation angle suppression mechanism 34 is provided to limit the rotatable range of the rotation shaft 32. Further, the rotation angle suppression mechanism 34 is configured to allow the rotation shaft 32 to rotate beyond the limited rotatable range when the steer-by-wire device 12 fails. The rotation angle suppression mechanism 34 changes the maximum turning angle of the second wheel 3 that is an auxiliary steered wheel. The rotation angle suppression mechanism 34 will be described later with reference to FIG.

  FIG. 2 is a cross-sectional view showing the rotation angle suppressing mechanism 34 according to the present embodiment. FIG. 2 shows a cross section perpendicular to the axial direction of the rotating shaft 32. As shown in the figure, the operating force transmission mechanism 14 includes a housing 38 having a substantially cylindrical shape for accommodating the rotating shaft 32. The rotating shaft 32 is rotatably held by the housing 38.

  The rotation angle suppression mechanism 34 includes a rotation restriction mechanism 100 for restricting the rotatable range of the rotation shaft 32 to a predetermined range, and a release mechanism 200 for releasing the restriction of the rotatable range by the rotation restriction mechanism 100. Prepare. The rotation restricting mechanism 100 is generally accommodated in the housing 38, and the release mechanism 200 is accommodated in the accommodating portion 40. The accommodating portion 40 is provided on the side portion of the housing 38 as a so-called cover for the release mechanism 200.

  The rotation restricting mechanism 100 includes a pair of pins 102. The set of pins 102 includes, for example, two pins. The pin 102 is inserted and fixed to the rotary shaft 32 along the radial direction of the rotary shaft 32, and one end protrudes from the rotary shaft 32 toward the inner surface of the housing 38. Therefore, the pin 102 rotates integrally with the rotating shaft 32. The pair of pins 102 are provided in parallel with an interval in the axial direction of the rotating shaft 32.

  The rotation restricting mechanism 100 includes a rod-like engagement member 104. The engaging member 104 is disposed inside the housing 38 with a gap from the rotating shaft 32 parallel to the axial direction of the rotating shaft 32. The engaging member 104 is provided at an axial position and length corresponding to the axial position and length of the pair of pins 102. One end of the engaging member 104 is supported by an annular member (not shown). The annular member surrounds the rotary shaft 32 and is supported by the rotary shaft 32 so as to be rotatable via a bearing. When the pin 102 rotates integrally with the rotating shaft 32, the pin 102 contacts the engaging member 104, and the pin 102 and the engaging member 104 are engaged. In this manner, the engaging member 104 is provided so as to be movable between the rotating shaft 32 and the housing 38 along the circumferential direction of the rotating shaft 32 while being supported by the annular member.

  The rotation restricting mechanism 100 further includes a lock key 106. The lock key 106 is provided so as to protrude into the housing 38 from a through hole 42 provided on a side surface of the housing 38. The through hole 42 connects the inside of the housing 38 and the inside of the accommodating portion 40. The shape of the lock key 106 is determined so that the lock key 106 does not interfere with the rotation of the rotary shaft 32 itself (that is, the lock key 106 does not contact the rotary shaft 32) when the lock key 106 protrudes into the housing 38. It has been. The lock key 106 is urged by an elastic member (for example, a spring) 108 in a direction from the through hole 42 toward the housing portion 40. The elastic member 108 is disposed between the edge of the through hole 42 on the outer peripheral surface of the housing 38 and the base of the lock key 106.

  The operation of the rotation restricting mechanism 100 will be described. FIG. 2 shows a state in which the rotating shaft 32 has rotated to the maximum in the R1 direction. The pin 102 of the rotation restricting mechanism 100 is engaged with the engaging member 104, and the engaging member 104 is engaged with the lock key 106. Thus, the rotation restricting mechanism 100 restricts the rotation shaft 32 from rotating further in the arrow R1 direction. When the operating member 5 is operated in the opposite direction by the driver from this state, the pin 102 is separated from the engaging member 104. If the rotation shaft 32 rotates in the R2 direction as it is, the rotation shaft 32 freely rotates until about one rotation. After approximately one rotation, the pin 102 engages with the engagement member 104. At this time, since the pair of pins 102 are provided with an interval in the axial direction of the rotating shaft 32, they pass without engaging with the lock key 106.

  When the rotating shaft 32 further rotates in the R2 direction, the pin 102 rotates in the arrow R2 direction while engaging with the engaging member 104. When the pin 102 is engaged with the engaging member 104 for about one rotation, the engaging member 104 hits the lock key 106. The pin 102 and the engaging member 104 cannot pass through the lock key 106, and as a result, the rotating shaft 32 cannot be rotated further in the direction of the arrow R2. In this way, the rotation restricting mechanism 100 can restrict the rotatable range of the rotating shaft 32 to about two rotations.

  As an alternative, the rotation restricting mechanism 100 may restrict the rotatable range of the rotating shaft 32 to a range other than two rotations. For example, the rotation restricting mechanism 100 may be configured to restrict the rotatable range of the rotating shaft 32 to a range of about one rotation. This is because the second wheel 3 steered by the rotation of the rotating shaft 32 may have a small steering angle when the steer-by-wire device 12 operates normally as described above. Therefore, the engaging member 104 may be omitted from the configuration shown in FIG. 2, and the pin 102 and the lock key 106 may be directly engaged.

  The release mechanism 200 includes a lever 202 that moves integrally with the lock key 106, a solenoid device 204 that drives the lever 202, and a rotation support portion 206 that rotatably supports the lever 202 with respect to the solenoid device 204. .

  The solenoid device 204 includes a cover 208, a plunger 210 incorporated in the cover 208, an electromagnetic coil (not shown), a spring, and the like. The power supply for the solenoid device 204 is the battery 30 described above, and switching between energization and deenergization of the solenoid device 204 is controlled by the ECU 28 (see FIG. 1). The solenoid device 204 is configured to pull the plunger 210 into the interior by electromagnetic force when energized, and to project the plunger 210 outward by the biasing force of the spring when energization is stopped.

  One end of the lever 202 is attached to the base of the lock key 106, and the other end of the lever 202 is connected to the plunger 210 via the rotation support unit 206. The tip of the lock key 106 is directed from the one end of the lever 202 in a direction substantially perpendicular to the longitudinal direction of the lever 202. The rotation support unit 206 is configured to convert the reciprocating motion of the plunger 210 into the rotation of the other end of the lever 202. In this way, the release mechanism 200 is configured such that the reciprocating motion of the plunger 210 is converted into the reciprocating motion of the lock key 106.

  The operation of the release mechanism 200 will be described. FIG. 2 shows a state in which the solenoid device 204 is energized from the battery 30. The plunger 210 is pulled into the solenoid device 204, and the lever 202 rotates in the direction of arrow R3 about the rotation support portion 206. With the rotation of the lever 202, the lock key 106 is inserted into the through hole 42 and protrudes into the housing 38. In this way, regulation of the rotatable range of the rotating shaft 32 by the rotation regulating mechanism 100 is realized. Therefore, the release mechanism 200 can be regarded as constituting a part of the rotation restricting mechanism 100.

  On the other hand, when the energization to the solenoid device 204 is stopped, the plunger 210 protrudes toward the outside of the solenoid device 204, and the lever 202 rotates about the rotation support portion 206 in the arrow R4 direction. The position of the lever 202 at that time is shown by a two-dot chain line in FIG. The lock key 106 retreats from the through hole 42 to the accommodating portion 40 together with the lever 202. Thus, the restriction on the rotatable range of the rotating shaft 32 is released, and the rotating shaft 32 is allowed to rotate beyond the rotatable range when energized.

  By the way, when an abnormality is detected in the steer-by-wire device 12, the steer-by-wire device 12 is usually stopped. That is, when the normal operation of the steer-by-wire device 12 is not guaranteed, the steer-by-wire device 12 is stopped. Specifically, the ECU 28 interrupts power supply from the battery 30 to the steer-by-wire device 12. Thus, the steer-by-wire device 12 is switched from the operating state to the non-operating state.

  Examples of abnormalities in the steer-by-wire device 12 include battery exhaustion, disconnection of the power supply line or signal line, errors in various sensors such as the operation amount sensor 22 or the turning angle sensor 26, calculation errors in the ECU 28, and damage to the turning motor 24. There is a moss welding of a motor driver installed in the ECU 28.

  The ECU 28 is configured to be able to detect at least one of various abnormalities of the steer-by-wire device 12 described above. A known method can be appropriately employed for such detection. The ECU 28 periodically determines whether the steer-by-wire device 12 is abnormal. When the ECU 28 determines that there is some abnormality in the steer-by-wire device 12, the steer-by-wire device 12 is considered to be in a fail state. When the steer-by-wire device 12 fails, the ECU 28 switches the steer-by-wire device 12 from the operating state to the non-operating state.

  The rotation angle suppression mechanism 34 is configured to allow the rotation shaft 32 to rotate beyond the normal rotatable range when the steer-by-wire device 12 fails. In the present embodiment, for this purpose, the ECU 28 of the steer-by-wire device 12 stops energization of the rotation angle suppression mechanism 34 in conjunction with the switching of the steer-by-wire device 12 to the non-operating state. Further, the ECU 28 continues energization to the rotation angle suppression mechanism 34 when the steer-by-wire device 12 is operating normally.

  Operation | movement of the vehicle steering apparatus 10 which concerns on this Embodiment provided with the above structure is demonstrated. When the operation member 5 is operated when the steer-by-wire device 12 is operating normally, the vehicle steering device 10 steers both the first wheel 2 and the second wheel 3. . The steer-by-wire device 12 steers the first wheel 2 based on the operation amount of the operation member 5. At the same time, the operation amount of the operation member 5 is mechanically transmitted to the second wheel 3 via the operation force transmission mechanism 14 to steer the second wheel 3.

  At this time, the rotation angle suppression mechanism 34 limits the rotatable range of the rotary shaft 32 by energizing the solenoid device 204. Thereby, the operable range of the operation member 5 and the turning angle range of the second wheel 3 are also limited, and the turning angle of the second wheel 3 is small. On the other hand, the steering unit 18 for the first wheel 2 is not mechanically connected to the steering unit 16 including the operation member 5, so that the steering angle of the first wheel 2 is determined by the rotation angle suppression mechanism 34. There are no restrictions. The first wheel 2 is steered in the steered angle range determined by the ECU 28 according to the operable range of the operation member 5. Thus, the steer-by-wire mainly contributes to the steering of the vehicle 1.

  On the other hand, when the operation member 5 is operated when the steer-by-wire device 12 is stopped (or when normal operation is not guaranteed), the vehicle steering device 10 steers only the second wheel 3. It will be. Energization to the rotation angle suppression mechanism 34 is stopped in conjunction with the stop of the steer-by-wire device 12, and the rotatable range of the rotating shaft 32 is expanded. Thereby, the operable range of the operation member 5 and the turning angle range of the second wheel 3 are also expanded. That is, the maximum turning angle of the second wheel 3 that is normally an auxiliary steered wheel is expanded. By operating the operation member 5, the driver can steer the second wheel 3 to the maximum turning angle determined mechanically in the operating force transmission mechanism 14. Thus, when the steer-by-wire device 12 fails, the vehicle 1 can be mechanically steered without relying on the steer-by-wire.

  As described above, according to the present embodiment, the vehicle steering apparatus 10 including the rotation angle suppression mechanism 34 that allows the rotation shaft 32 to allow rotation exceeding the limited rotatable range when the steer-by-wire apparatus 12 fails is provided. Is done. When the steer-by-wire device 12 fails, the operation range of the operation member 5 is expanded, and accordingly, the turning angle range of the second wheel 3 mechanically connected to the operation member 5 is also expanded. Normally, the second wheel 3 that is used for steering in an auxiliary manner can be utilized to ensure that the vehicle 1 can turn right or left even when the steer-by-wire device 12 fails.

  Further, according to the present embodiment, it is possible to realize the countermeasure against the failure without relying on adding a dedicated device for the countermeasure against the failure to the vehicle steering apparatus 10. For example, there is no need to add a mechanical backup system between the first wheel 2 and the steer-by-wire device 12. In addition, since the vehicle 1 can be mechanically steered by the second wheels 3 when the steer-by-wire device 12 fails, it is not essential to multiplex the electrical system for the steer-by-wire device 12. Therefore, an increase in cost that can be caused by the addition of such a dedicated device can be suppressed. It is also advantageous that there is no need to secure a mounting space for these devices.

  On the other hand, since the vehicle steering apparatus 10 is configured to steer the vehicle 1 mainly by steer-by-wire during normal times, the advantages of steer-by-wire can be fully utilized. For example, good steering performance can be provided by control during normal times. Further, since the steer-by-wire device 12 does not have a mechanism for mechanically connecting the operation member 5 and the first wheel 2, there is an advantage that the degree of freedom in designing the mounting location is high.

  Furthermore, according to the present embodiment, the energization to the rotation angle suppression mechanism 34 is stopped in conjunction with the switching of the steer-by-wire device 12 to the non-operating state, and the rotation limit of the rotation shaft 32 by the rotation angle suppression mechanism 34 is restricted. It is canceled by stopping energization and accompanying mechanical operation. Therefore, when the steer-by-wire device 12 fails, the rotation restriction of the rotation angle suppression mechanism 34 can be reliably released and the turning angle range of the second wheel 3 can be increased.

  As described above, the present invention has been described with reference to the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and the configurations of the embodiments are appropriately combined or replaced. Those are also included in the present invention. Further, it is possible to appropriately change the combination and processing order in each embodiment based on the knowledge of those skilled in the art and to add various modifications such as various design changes to each embodiment. Embodiments to which is added can also be included in the scope of the present invention.

  For example, the rotation angle suppression mechanism 34 may be configured to apply a reaction force for restricting the rotation of the rotation shaft 32 to the rotation shaft 32 by energization and to release the reaction force by stopping the energization. Even in this case, the steer-by-wire device 12 may stop energization of the rotation angle suppression mechanism 34 at the time of a failure as in the above-described embodiment. Even in this case, the reaction force for limiting the rotation by the rotation angle suppression mechanism 34 can be reliably released when the steer-by-wire device 12 fails.

  Therefore, the operation force transmission mechanism 14 may include a reaction force generation motor for generating an operation reaction force to the operation member 5. Alternatively, the vehicle steering device 10 may include a power steering device provided in the operating force transmission mechanism 14, and the power steering device may be used for reaction force generation. In this case, the rotation angle suppression mechanism 34 may be configured by allowing the operation member 5 to be operated only within a set range by a reaction force (for example, motor torque) when the steer-by-wire device 12 is operating normally. . For example, the ECU 28 may control the rotation angle suppression mechanism 34 according to the set range.

  In the above-described embodiment, the turning angle range of the second wheel 3 is normally restricted, and the restriction is released when the steer-by-wire device 12 fails. Instead of the second wheel 3 or together with the second wheel 3, the turning angle range of the first wheel 2 may be restricted, and the restriction may be released when the steer-by-wire device 12 fails. In that case, the steer-by-wire device 12 includes a connection mechanism including a rotation shaft for mechanically connecting the operation member 5 and the first wheel 2, and the rotation angle suppression mechanism 34 is provided on the rotation shaft. Good.

  DESCRIPTION OF SYMBOLS 1 vehicle, 2 1st wheel, 3 2nd wheel, 5 operation member, 10 vehicle steering apparatus, 12 steer-by-wire apparatus, 14 operation force transmission mechanism, 32 rotating shaft, 34 rotation angle suppression mechanism.

Claims (5)

A vehicle steering apparatus for a vehicle, comprising: a first wheel that is steered by a steer-by-wire device; and a second wheel that is steered by mechanical connection with an operation member for a driver. The steering device is configured to steer the first wheel and the second wheel by an input to the operation member,
The operation member and the second wheel include a rotation shaft connected to the operation member to be rotatable by the input, and transmit the input to the second wheel regardless of an operating state of the steer-by-wire device. An operating force transmission mechanism that mechanically connects
A rotation angle suppression mechanism for limiting a rotatable range of the rotation shaft,
The vehicle steering apparatus according to claim 1, wherein the rotation angle suppression mechanism is configured to allow the rotation shaft to rotate beyond the rotatable range when the steer-by-wire apparatus fails.   The turning angle of the second wheel corresponding to the rotatable range is set to be smaller than the turning angle of the first wheel by the steer-by-wire device. Vehicle steering system. The rotation angle suppression mechanism is configured to release the limitation of the rotatable range by stopping energization,
3. The vehicle steering apparatus according to claim 1, wherein the steer-by-wire device stops energization of the rotation angle suppression mechanism during the failure. 4. The rotation angle suppression mechanism is configured to apply a reaction force to the rotation shaft to restrict rotation of the rotation shaft by energization, and to release the reaction force by stopping energization.
4. The vehicle steering apparatus according to claim 1, wherein the steer-by-wire device stops energization of the rotation angle suppression mechanism during the failure. 5. A vehicle steering device for a vehicle comprising: a wheel steered by a steer-by-wire device; and a wheel steered by mechanical connection with an operation member for a driver,
A rotating shaft connected to the operating member to be rotatable by an input to the operating member;
A rotation angle suppression mechanism for limiting a rotatable range of the rotation shaft,
The vehicle steering apparatus according to claim 1, wherein the rotation angle suppression mechanism is configured to allow the rotation shaft to rotate beyond the rotatable range when the steer-by-wire apparatus fails.

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