JP5880945B2 - Rear wheel steering device - Google Patents

Description

  The present invention relates to a rear wheel steering device.

Patent Document 1 proposes a technique for regulating rear wheel steering in a rear wheel steering device by energizing a solenoid and inserting a plunger into a rack shaft hole when the front wheel steering angle exceeds a set steering angle. Has been. In Patent Document 1, a mechanical steering angle switch is provided in a solenoid energization circuit to prevent malfunction of rear wheel steering regulation.
In Patent Document 2, a rear wheel steering device that separates a motor used at the time of small steering angle steering from a motor used at the time of large steering angle steering, and always regulates the stroke of the rod connected to the rear wheel when the small steering angle motor is driven. Proposed. This prevents large steering angle steering from being performed during high-speed small steering angle control.

JP-A-7-165099 JP-A-8-268314

When a sensor for detecting that the steered shaft is in the neutral position and a high-output drive mechanism such as a motor for returning the steered shaft to the neutral position are necessary, the structure of the rear wheel steering device becomes complicated. The rear wheel steering device becomes larger. Further, if a sensor, a motor, or the like is out of order, the steered shaft may not be returned to the neutral position when necessary.
The present invention is to provide a small rear wheel steering device that can reliably return the rear wheel steering shaft to the neutral position when necessary.

In order to achieve the object, the invention of claim 1 is directed to a first engagement tooth (27) provided on a rear wheel steering shaft (11) and a first swinging claw that engages with the first engagement tooth. (28) and a first ratchet mechanism (21) including a first biasing spring (29) for swinging and biasing the first swinging claw to a home position in the swinging direction, and the first ratchet A first switching mechanism (23) that switches the mechanism to a ratchet state that only allows movement in the first axial direction (X1) from the neutral position of the rear wheel steering shaft; and a second switching mechanism provided on the rear wheel steering shaft. An engagement tooth (31), a second swinging claw (32) engaged with the second engagement tooth, and a second biasing biasing of the second swinging claw to the home position in the swinging direction . A second ratchet mechanism (24) including an urging spring (33); and the second ratchet mechanism is made neutral with the rear wheel turning shaft. A second switching mechanism for switching the ratchet state that allows movement only placed et the second axial (X2) (26), wherein the first switching mechanism, from said first swing claw said home position A first restricting member (35) displaceable between a restricting position for restricting swinging in a swinging direction allowing movement of the rear wheel steering shaft in the second axis direction and a restriction releasing position for releasing the restriction; A first drive member (22) for driving the first restriction member to the restriction position and the restriction release position, wherein the second switching mechanism is configured such that the second swinging claw is moved from the home position to the rear position. A second restricting member (36) displaceable between a restricting position for restricting swinging in a swinging direction allowing movement of the wheel turning shaft in the first axis direction and a restriction releasing position for releasing the restriction; 2 The restriction member is moved to the restriction position and the restriction release position. A second drive member (25) that drives the first restricting member in a direction (P1) that intersects the swinging direction of the first swinging claw (P1). (22c), and the second drive member includes a solenoid (25c) for moving the second restricting member forward and backward in a direction (P2) intersecting the swinging direction of the second swinging claw ( 3) is provided.

In addition, although the alphanumeric character in a parenthesis represents the corresponding component etc. in embodiment mentioned later, this does not mean that this invention should be limited to those embodiment as a matter of course. The same applies hereinafter .

According to a second aspect of the present invention, a control device (16) for controlling the operation of the first drive member and the second drive member is provided, and the control device includes the first restriction member and the second restriction member. The first drive member and the second drive member may be controlled to be displaced so that the first ratchet mechanism and the second ratchet mechanism are switched to a ratchet state by being displaced to a restriction position.

Further, as in claim 3 , a running state detection sensor (19) for detecting the running state of the vehicle, a steering state detection sensor (18, 19) for detecting the steering state of the vehicle, and a wheel for turning the rear wheel. A steering actuator (14), and the control device steers the steering actuator based on the traveling state detected by the traveling state detection sensor and the steering state detected by the steering state detection sensor. And a function of switching the first ratchet mechanism and the second ratchet mechanism to a ratchet state when a failure occurs in at least one of the traveling state detection sensor, the steering state detection sensor, and the steering actuator. You may do it.

As in 請 Motomeko 4, in the neutral position, between the first teeth and second teeth of said steering shaft, said first swing pawl and the second swing claw is arranged It may be configured as follows.

  According to the first aspect of the present invention, when the corresponding ratchet mechanism is switched to the ratchet state by each switching mechanism, each ratchet mechanism restricts the movement of the steered shaft in the corresponding axial direction from the neutral position. Therefore, the steered shaft can be automatically returned to the neutral position by the self-alignment torque from the road surface, and can be reliably held at the neutral position. A sensor for detecting the neutral position, a motor for returning the steered shaft to the neutral position, and the like can be dispensed with, and miniaturization can be achieved with a simple structure using a ratchet mechanism.

Further , in each switching mechanism, the corresponding ratchet mechanism can be easily switched to the ratchet state by displacing the regulating member corresponding to each driving member to the regulating position.
Further, the solenoid of each driving member advances the corresponding regulating member in a direction crossing the swinging direction of the corresponding swinging claw so that the corresponding swinging claw swings in a predetermined swinging direction. By restricting, the corresponding ratchet mechanism can be switched to the ratchet state. If the solenoid is used, the on / off operation is reliable, and as a result, the steered shaft can be surely automatically returned to the neutral position.
According to the invention of claim 2 , each control member can be displaced to the control position by controlling the drive of each drive member.

According to the invention of claim 3 , when a failure occurs in any of the sensor for detecting the traveling state and steering state of the vehicle and the steering actuator, the steering shaft is automatically returned to the neutral position, Travel stability can be improved .

According to the invention of claim 4 , since both the swinging claws are arranged between the engaging teeth of the steered shaft at the neutral position, further downsizing can be achieved.

It is a mimetic diagram of a four-wheel steering device to which a rear-wheel steering device of one embodiment of the present invention was applied. It is a schematic sectional drawing of the neutral position automatic return apparatus of a rear-wheel steering apparatus. It is a flowchart which shows the flow of control of ECU. It is a schematic sectional drawing of the neutral position automatic return apparatus when each ratchet mechanism is a non-ratchet state. (A) and (b) are a state in which the first ratchet mechanism allows movement of the steered shaft in the first axial direction, and a state in which the first ratchet mechanism allows movement in the second axial direction, respectively. Show. It is a schematic sectional drawing of the neutral position automatic return apparatus when each ratchet mechanism is a non-ratchet state. (A) and (b) are a state in which the second ratchet mechanism allows movement of the steered shaft in the first axial direction, and a state in which the second ratchet mechanism allows movement in the second axial direction, respectively. Show. It is a schematic sectional drawing of the neutral position automatic return apparatus when each ratchet mechanism is a ratchet state. (A) shows a state in which the steered shaft displaced from the neutral position to the second axial direction side is allowed to move in the first axial direction, and (b) shows a state where the turning shaft reaches the neutral position. The rudder axis is shown in a neutral position. It is a schematic sectional drawing of the neutral position automatic return apparatus when each ratchet mechanism is a ratchet state. (A) shows a state in which the steered shaft displaced from the neutral position to the first axial direction side is allowed to move in the second axial direction, and (b) shows a state where the turning shaft reaches the neutral position. The rudder axis is shown in a neutral position.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of a four-wheel steering device including a rear wheel steering device according to an embodiment of the present invention. Referring to FIG. 1, the four-wheel steering device 1 includes a front wheel steering device 2 and a rear wheel steering device 3. The front wheel steering device 2 includes a steering member 4 such as a steering wheel, a pinion shaft 5 that rotates as the steering member 4 rotates, a front wheel steering shaft 6 that includes a rack shaft that meshes with the pinion shaft 5, and a front end steering. A pair of tie rods 7 connected to both ends of a rack shaft as the shaft 6 and left and right front wheels 8 connected to each tie rod 7 via a knuckle arm (not shown) are provided. The pinion shaft 5 and the rack shaft as the front wheel turning shaft 6 constitute a rack and pinion mechanism A as a front wheel turning mechanism.

  The rear wheel steering device 3 includes a housing 10 fixed to the vehicle body 9, and a rear wheel steering shaft supported by the housing 10 so as to be movable in the axial direction (first axial direction X1 and second axial direction X2) and non-rotatable. 11, a pair of tie rods 12 connected to both ends of the rear wheel steering shaft 11, and left and right rear wheels 13 connected to each tie rod 12 via a knuckle arm (not shown).

  The rear wheel steering device 3 constitutes a so-called steer-by-wire system in which the mechanical connection between the steering member 4 and the left and right rear wheels 13 is released. That is, the rear wheel steering device 3 is configured to rotate the steering actuator 14, which is driven by a rotating operation of the steering member 2, for example, an electric motor, and the rotational motion of the steering actuator 14 in the axial direction of the rear wheel steering shaft 11 ( A ball screw mechanism 15 for converting linear motion in the first axial direction X1 and the second axial direction X2), an ECU 16 (Electronic Control Unit) as a control device for steering control of the steering actuator 14, and rear wheel steering when necessary And a neutral position automatic return device 17 that automatically returns the shaft 11 to the neutral position.

  The rear wheel steering device 3 includes a steering angle sensor 18 (steering state detection sensor) that detects the steering angle θh of the steering member 4, a vehicle speed sensor 19 (traveling state detection sensor) that detects the vehicle speed V, and rear wheel steering. A turning angle sensor 20 (steering state detection sensor) that detects the turning angle θw of the rear wheel 13 in accordance with the positions of the shaft 11 in the axial directions X1 and X2 is provided. Detection signals from the steering angle sensor 18, the vehicle speed sensor 19, and the turning angle sensor 20 are input to the ECU 16.

  The ECU 16 controls the steering actuator 14 based on the steering angle θh detected by the steering angle sensor 18 and the vehicle speed V detected by the vehicle speed sensor 19. Specifically, the target turning angle is set based on the detected steering angle θh and the detected vehicle speed V. Then, based on the deviation between the target turning angle and the turning angle θw detected by the turning angle sensor 20, drive control (steering control) of the turning actuator 14 is performed via a drive circuit (not shown). )

  The neutral position automatic return device 17 includes a non-ratchet state that allows the rear wheel turning shaft 11 to move in both the first axial direction X1 (for example, left) and the second axial direction X2 (for example, right), and the rear wheel rotation. A first ratchet mechanism 21 that can be switched to a ratchet state that allows only movement in the first axial direction X1 from the neutral position of the rudder shaft 11 and a first drive member 22 that switches the first ratchet mechanism 21 to the ratchet state are included. And a first switching mechanism 23.

  Further, the neutral position automatic return device 17 has a non-ratchet state that allows the rear wheel steered shaft 11 to move in both the first axial direction X1 and the second axial direction X2, and the neutral position from the neutral position of the rear wheel steered shaft 11. A second ratchet mechanism 24 that can be switched to a ratchet state that only allows movement in the biaxial direction X2 and a second switching mechanism 26 that includes a second drive member 25 that switches the second ratchet mechanism 24 to the ratchet state. ing.

  As shown in FIG. 2, the first ratchet mechanism 21 includes a first engagement tooth 27 provided on the outer periphery 11 a of the rear wheel steering shaft 11 and a first swinging claw 28 that engages with the first engagement tooth 27. And a first biasing spring 29 that swings and biases the first swinging claw 28. The first swing claw 28 is supported by the housing 10 via the first support shaft 30 so as to be swingable around the first support shaft 30. The first biasing spring 29 biases the first swinging claw 28 to the home position in the swinging direction (intermediate position of the swinging range).

  The second ratchet mechanism 24 includes a second engagement tooth 31 provided on the outer periphery 11a of the rear wheel turning shaft 11, a second swinging claw 32 that engages with the second engagement tooth 31, and a second swinging claw. And a second urging spring 33 for urging and oscillating 32. The second swing claw 32 is supported by the housing 10 via the second support shaft 34 so as to be swingable around the second support shaft 34. The second urging spring 33 urges the second swing claw 32 to the home position in the swing direction (intermediate position of the swing range).

  The first switching mechanism 23 includes a first restriction member 35 and a first drive member 22. The first restricting member 35 has a swinging direction in which the first swinging claw 28 allows the rear wheel turning shaft 11 to move in the second axial direction X2 from the home position (the second swinging is counterclockwise in FIG. 2). It can be displaced between a restricting position for restricting swinging in the movement direction Y2) and a restricting release position for releasing the restriction (see FIG. 4A). The first drive member 22 drives the first restriction member 35 to the restriction position shown in FIG. 2 and the restriction release position shown in FIG.

  The second switching mechanism 26 includes a second restriction member 36 and a second drive member 25. The second restricting member 36 has a swinging direction in which the second swinging claw 32 allows the rear wheel turning shaft 11 to move in the first axial direction X1 from the home position (the first swinging is clockwise in FIG. 2). It is possible to move to a restriction position that restricts swinging in the direction Z1) and a restriction release position that releases the restriction (FIG. 4A). The second drive member 25 drives the second restriction member 36 to the restriction position shown in FIG. 2 and the restriction release position shown in FIG.

The first engagement teeth 27 are arranged closer to the first axial direction X1 than the second engagement teeth 31, and the second engagement teeth 31 are arranged closer to the second axial direction X2 than the first engagement teeth 27. Has been. The first engagement teeth 27 and the second engagement teeth 31 are separated from each other by a predetermined distance in the axial directions X1 and X2 of the rear wheel steering shaft 11.
The first engagement teeth 27 include an inclined tooth surface 27a inclined with respect to the axial directions X1 and X2 of the rear wheel turning shaft 11 and an orthogonal tooth surface 27b orthogonal to the axial directions X1 and X2 of the rear wheel turning shaft 11. Have. In one first engagement tooth 27, the inclined tooth surface 27a is disposed closer to the first axial direction X1 than the orthogonal tooth surface 27b.

  The second engagement tooth 31 includes an inclined tooth surface 31a inclined with respect to the axial directions X1 and X2 of the rear wheel turning shaft 11 and an orthogonal tooth surface 31b orthogonal to the axial directions X1 and X2 of the rear wheel turning shaft 11. Have. In one second engagement tooth 31, the inclined tooth surface 31 a is arranged on the second axial direction X2 side with respect to the orthogonal tooth surface 31 b. The inclined tooth surface 27a of the first engaging tooth 27 and the inclined tooth surface 31a of the second engaging tooth 31 are inclined in directions opposite to each other.

  The first swing claw 28 has a first end 281 and a second end 282, and the first support shaft 30 is disposed between the both ends 281 and 282. A first engagement portion 28 a that engages with the inclined tooth surface 27 a of the first engagement tooth 27 is provided at the first end portion 281 of the first swing claw 28. The first engaging portion 28a is inclined with respect to the axial directions X1 and X2 of the rear wheel turning shaft 11 in a state where the first swinging claw 28 is at the home position.

  The side portion 28b of the first swing claw 28 (the side portion 28b is orthogonal to the axial directions X1 and X2 of the rear wheel turning shaft 11 with the first swing claw 28 in the home position). The end portion 281 has a second engagement portion 28 c that engages with the orthogonal tooth surface 27 b of the first engagement tooth 27. The side portion 28 b of the first swing claw 28 has a third engagement portion 28 d that engages with the first restriction member 35 at the second end portion 282.

  The first urging spring 29 is constituted by, for example, a coil spring. One end of the first urging spring 29 is fixed to the protrusion 10 b provided on the inner periphery 10 a of the housing 10, and the other end of the first urging spring 29 is connected to the second end 282 of the first swinging claw 28. It is fixed. When the first swing claw 28 is tilted in any tilt direction (first swing direction Y1 or second swing direction Y2) from the home position (corresponding to the upright state shown in FIG. 2), the first biasing spring 29 is provided. Exerts an urging force (restoring force to the home position) on the first swinging claw 28 in the direction opposite to the inclination direction.

  The second swing claw 32 has a first end 321 and a second end 322, and the second support shaft 34 is disposed between the both ends 321 and 322. A first engagement portion 32 a that engages with the inclined tooth surface 31 a of the second engagement tooth 31 is provided at the first end 321 of the second swing claw 32. The first engaging portion 32a is inclined with respect to the axial directions X1 and X2 of the rear wheel turning shaft 11 with the second swinging claw 32 in the home position.

  The side portion 32b of the second swing claw 32 (the side portion 32b is orthogonal to the axial directions X1 and X2 of the rear wheel turning shaft 11 with the second swing claw 32 in the home position). The end portion 321 has a second engagement portion 32 c that engages with the orthogonal tooth surface 31 b of the second engagement tooth 31. The side portion 32 b of the second swing claw 32 has a third engagement portion 32 d that engages with the second restriction member 36 at the second end portion 322.

  The second urging spring 33 is constituted by, for example, a coil spring. One end of the second biasing spring 33 is fixed to the protrusion 10 c provided on the inner periphery 10 a of the housing 10, and the other end of the second biasing spring 33 is connected to the second end 322 of the second swinging claw 32. It is fixed. When the second swing claw 32 is tilted in any tilt direction (first swing direction Z1 or second swing direction Z2) from the home position (corresponding to the upright state shown in FIG. 2), the second biasing spring 33 is moved. Exerts a biasing force (restoring force to the home position) on the second swinging claw 32 in the direction opposite to the inclination direction.

The disposition interval D1 between the orthogonal tooth surface 27b of the first engaging tooth 27 and the orthogonal tooth surface 31b of the second engaging tooth 31 that are close to each other is the second engaging portion of the swinging claws 28 and 32 at the home position. It is configured to be equal to the distance D2 between 28c and 32c.
The first drive member 22 of the first switching mechanism 23 is composed of an electromagnetic actuator, and a main body 22a and a rod 22b that advances and retreats from the main body 22a in a crossing direction P1 that intersects the swing directions Y1 and Y2 of the first swing claw 28. And a solenoid 22c built in the main body 22a and a compression coil spring 22d for urging the rod 22b in the extending direction. The first restricting member 35 is fixed to the end of the rod 22b, and the compression coil spring 22d is interposed between the first restricting member 35 and the main body 22a.

When the solenoid 22c of the first drive member 22 is turned off (excitation is released), the rod 22b is extended by the urging force of the compression coil spring 22d. Thereby, the 1st control member 35 is displaced to the control position (refer FIG. 2) engaged with the 3rd engaging part 28d of the 1st rocking claw 28. FIG. As a result, only the swing of the first swing claw 28 in the first swing direction Y1 is restricted [see FIG. 6 (a)].
Further, when the solenoid 22c is turned on (excited), the rod 22b contracts by the electromagnetic force of the solenoid 22c. Thereby, the 1st control member 35 is displaced to the control release position (refer FIG. 4 (a), (b)) which cancels | releases engagement with the 3rd engaging part 28d of the 1st rocking claw 28. FIG. As a result, the first swinging claw 28 can swing in both swinging directions Y1, Y2.

  As shown in FIG. 2, the second drive member 25 of the second switching mechanism 26 is composed of an electromagnetic actuator and intersects the body 25a and the swing directions Z1 and Z2 of the second swing claw 32 from the body 25a. It includes a rod 25b that advances and retreats in P2, a solenoid 25c built in the main body 25a, and a compression coil spring 25d that urges the rod 25b in the extending direction. The second restricting member 36 is fixed to the end of the rod 25b, and the compression coil spring 25d is interposed between the second restricting member 36 and the main body 25a.

When the solenoid 25c of the second drive member 25 is turned off (excitation is released), the rod 25b is extended by the urging force of the compression coil spring 52d. As a result, the second restricting member 36 is displaced to a restricting position (see FIG. 2) that engages with the third engaging portion 32 d of the second swinging claw 32. As a result, only the swing of the second swing claw 32 in the second swing direction Z2 is restricted [see FIG. 7 (a)].
When the solenoid 25c is turned on (excited), the rod 25b contracts by the electromagnetic force of the solenoid 25c. Thereby, the 2nd control member 36 is displaced to the control release position (refer FIG. 5 (a), (b)) which cancels | releases engagement with the 3rd engaging part 32d of the 2nd rocking claw 32. FIG. As a result, the second swing claw 32 can swing in both swing directions Z1 and Z2.

FIG. 3 is a flowchart showing a control flow of the ECU 16. In response to activation of the system, the solenoids 22c and 25c of the ratchet mechanisms 21 and 24 are turned on in step S1. Thereby, each ratchet mechanism 21 and 24 will be in a non-ratchet state, and each rocking claw 28 and 32 will be in the state which can rock | fluctuate in any rocking direction.
As a result, the first ratchet mechanism 21 allows the rear wheel steered shaft 11 to move in the first axial direction X1 as shown in FIG. 4A, and as shown in FIG. The rear wheel turning shaft 11 is allowed to move in the second axial direction X2. The second ratchet mechanism 24 allows the rear wheel turning shaft 11 to move in the first axial direction X1 as shown in FIG. 5 (a), and the rear wheel turning as shown in FIG. 5 (b). The movement of the shaft 11 in the second axial direction X2 is allowed.

Next, in step S2, various signals related to rear wheel steering (for example, the driving current value of the electric motor as the steering angle sensor 18, the vehicle speed sensor 19, the turning angle sensor 20, and the turning actuator 14) are input. In step S3, whether or not a failure has occurred is determined based on whether or not the input signal deviates from a normal value.
If it is determined in step S3 that no failure has occurred (NO in step S3), the process returns to step S2, and the processing in steps S2 and S3 is repeated to monitor the occurrence of failure.

  If it is determined in step S3 that a failure has occurred (YES in step S3), the process proceeds to step S4, and the solenoids 22c and 25c of the ratchet mechanisms 21 and 24 are turned off. As a result, the rods 22b and 25b of the drive members 22 and 25 are extended, and the restricting members 35 and 36 are displaced to the restricting positions. Thereby, each ratchet mechanism 21 and 24 will be in a ratchet state.

  When switched to the ratchet state in this way, for example, as shown in FIG. 6A, the rear wheel turning shaft 11 is displaced from the neutral position in the second axial direction X2 [leftward in FIG. 6A]. In this case, the first ratchet mechanism 21 in the ratchet state is displaced in the first axial direction X1 by the self-alignment torque ST received by the rear wheel 13 from the road surface [FIG. ) In the direction of the white arrow].

  As a result, as shown in FIG. 6B, when the rear wheel turning shaft 11 reaches the neutral position, the swinging claws 28 and 32 of the ratchet mechanisms 21 and 24 are connected to the corresponding regulating members 35 and 36, respectively. Bidirectional swinging is restricted by the corresponding orthogonal tooth surfaces 27b and 31b, and as a result, the rear wheel turning shaft 11 is restricted from moving in both directions (first axial direction X1 and second axial direction X2). , Locked in the neutral position.

  On the other hand, when switched to the ratchet state, for example, as shown in FIG. 7A, the rear wheel turning shaft 11 is displaced from the neutral position in the first axial direction X1 [rightward in FIG. 6A]. In this case, the second ratchet mechanism 24 in the ratchet state is displaced in the second axial direction X2 by the self-alignment torque ST received by the rear wheel 13 from the road surface [FIG. In the direction of the white arrow].

  As a result, as shown in FIG. 7B, when the rear wheel turning shaft 11 reaches the neutral position, the swinging claws 28 and 32 of the ratchet mechanisms 21 and 24 are connected to the corresponding regulating members 35 and 36, respectively. Bidirectional swinging is restricted by the corresponding orthogonal tooth surfaces 27b and 31b, and as a result, the rear wheel turning shaft 11 is restricted from moving in both directions (first axial direction X1 and second axial direction X2). , Locked in the neutral position.

  According to this embodiment, when the corresponding ratchet mechanisms 21 and 24 are switched to the ratchet state by the switching mechanisms 23 and 26, the respective ratchet mechanisms 21 and 24 correspond to the axial directions of the rear wheel turning shaft 11 from the neutral position. Restrict movement to X1 and X2. Therefore, the rear wheel turning shaft 11 can be automatically returned to the neutral position by the self-alignment torque ST from the road surface, and can be reliably held at the neutral position. Therefore, a sensor for detecting the neutral position, a motor for returning the rear wheel turning shaft to the neutral position, and the like can be eliminated, and downsizing can be achieved with a simple structure using the ratchet mechanisms 21 and 24.

  Further, in each switching mechanism 23, 26, the corresponding ratchet mechanism 21, 24 can be easily switched to the ratchet state by displacing the corresponding regulating member 35, 36 to the regulating position by each drive member 22, 25. . Specifically, the ECU 16 can control the drive members 22 and 25 to displace the restricting members 35 and 36 to the restricting positions.

In addition, a sensor (vehicle speed sensor 19 in the present embodiment) that detects the running state of the vehicle, a sensor (steering angle sensor 18 and steering angle sensor 20 in the present embodiment) that detects the steering state of the vehicle, a steering actuator When a failure occurs in any one of the fourteen wheels, the rear wheel turning shaft 11 can be automatically returned to the neutral position to improve running stability.
In addition, the solenoids 22c and 25c of the drive members 22 and 25 correspond to the swinging directions Y1 and Y2 of the corresponding swinging claws 28 and 32; By advancing 36, the swinging of the corresponding swinging claws 28 and 32 in a predetermined swinging direction is restricted, and each ratchet mechanism 21 and 24 can be switched to the ratchet state. With the solenoids 22c and 25c, the on / off operation is reliable, and as a result, the rear wheel turning shaft 11 can be surely automatically returned to the neutral position and held at the neutral position.

Further, as shown in FIG. 2, in the neutral position, since the swinging claws 28 and 32 are disposed between the engaging teeth 27 and 31 of the rear wheel steering shaft 11, the rear wheel steering device 3 is further layered. Can be miniaturized.
In addition, this invention is not limited to the said embodiment. For example, in the embodiment described above, the neutral position automatic return device 17 is configured to automatically return the rear wheel steered shaft 11 to the neutral position when a failure occurs. However, the present invention is not limited to this. The neutral position automatic return device 17 may function as a neutral position locking device that locks the rear wheel steering shaft 11 at the neutral position in a normal time when no failure occurs. In addition, various modifications can be made within the scope of the claims of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Four wheel steering device, 2 ... Front wheel steering device, 3 ... Rear wheel steering device, 4 ... Steering member, 9 ... Vehicle body, 10 ... Steering housing, 11 ... Rear-wheel steering shaft, 12 ... Tie rod, 13 ... Rear wheel , 14 ... Steering actuator, 15 ... Ball screw mechanism, 16 ... ECU (control device), 17 ... Neutral position automatic return device, 18 ... Steering angle sensor (steering state detection sensor), 19 ... Vehicle speed sensor (running state detection sensor) ), 20 ... Steering angle sensor (steering state detection sensor), 21 ... First ratchet mechanism, 22 ... First drive member, 22a ... Main body, 22b ... Rod, 22c ... Solenoid, 22d ... Compression coil spring, 23 ... First 1 switching mechanism, 24 ... second ratchet mechanism, 25 ... second drive member, 25a ... main body, 25b ... rod, 25c ... solenoid, 25d ... compression coil spring, 26 ... second switching mechanism, 27 ... second Engaging teeth, 27a ... inclined tooth surfaces, 27b ... orthogonal tooth surfaces, 28 ... first swinging claw, 28a ... first engaging portion, 28b ... side portion, 28c ... second engaging portion, 28d ... third relationship Joint part, 29 ... first biasing spring, 30 ... first support shaft, 31 ... second engaging tooth, 31a ... inclined tooth surface, 31b ... orthogonal tooth surface, 32 ... second swing claw, 32a ... first Engagement part, 32b ... side part, 32c ... second engagement part, 32d ... third engagement part, 33 ... second urging spring, 34 ... second support shaft, 35 ... first regulating member, 36 ... first 2 restricting members, P1, P2 ... intersecting direction, X1 ... first axis direction, X2 ... second axis direction, Y1 ... first swing direction, Y2 ... second swing direction, Z1 ... first swing direction, Z2 ... Second oscillation direction

Claims (4)

A first engagement tooth provided on the rear wheel steering shaft, a first swinging claw that engages with the first engagement tooth, and the first swinging claw swinging to a home position in the swinging direction . A first ratchet mechanism including a first biasing spring that biases;
A first switching mechanism that switches the first ratchet mechanism to a ratchet state that only allows movement in a first axial direction from a neutral position of the rear wheel steering shaft;
A second engaging tooth provided on the rear wheel steering shaft, a second swinging claw engaged with the second engaging tooth, and swinging the second swinging claw to a home position in the swinging direction. A second ratchet mechanism including a second biasing spring for biasing;
A second switching mechanism that switches the second ratchet mechanism to a ratchet state that only allows movement in the second axial direction from a neutral position of the rear wheel steering shaft ;
The first switching mechanism releases the restriction position and restriction for restricting the first swinging claw from swinging in the swinging direction allowing movement of the rear wheel steering shaft in the second axial direction from the home position. A first restricting member that is displaceable to a restriction release position, and a first drive member that drives the first restriction member to the restriction position and the restriction release position.
The second switching mechanism releases the restriction position and restriction for restricting the second swinging pawl from swinging in the swinging direction allowing movement of the rear wheel steering shaft in the first axial direction from the home position. A second restriction member that is displaceable to a restriction release position, and a second drive member that drives the second restriction member to the restriction position and the restriction release position,
The first drive member includes a solenoid that advances and retracts the first restricting member in a direction crossing a swinging direction of the first swinging claw,
The second drive member includes a solenoid for moving the second restricting member in a direction crossing the swinging direction of the second swinging claw . The control device according to claim 1 , comprising a control device that controls operations of the first drive member and the second drive member,
The control device displaces the first restricting member and the second restricting member to a restricting position to switch the first ratchet mechanism and the second ratchet mechanism to a ratchet state. (2) A rear wheel steering device having a function of controlling driving of a driving member. In Claim 2 , the traveling state detection sensor which detects the traveling state of a vehicle,
A steering state detection sensor for detecting the steering state of the vehicle;
A steering actuator that steers the rear wheels,
The control device includes a function of steering-controlling a steering actuator based on a traveling state detected by the traveling state detection sensor and a steering state detected by the steering state detection sensor, the traveling state detection sensor, and the steering A rear wheel steering device having a function of switching the first ratchet mechanism and the second ratchet mechanism to a ratchet state when a failure occurs in at least one of a state detection sensor and the steering actuator. In any one of claims 1 to 3, in the neutral position, between the first teeth and the second teeth of the rear wheel steering shaft, the first swing pawl and the second swing A rear wheel steering device configured to have claws disposed thereon.

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