JPH03112783A - Four-wheel steering device - Google Patents

Abstract

PURPOSE:To improve rigidity for a reverse input to a rear wheel from the ground surface while obtaining the characteristic, in which a rear wheel steering angle is held to zero degree during the time of a small front wheel steering angle thereafter increased in accordance with an increase of the front wheel steering angle, by improving the structure of a steering characteristic giving mechanism in a rear wheel steering device. CONSTITUTION:A rear wheel steering device 20, in which a steering amount of a front wheel steering device is transmitted through a pair of control cables 65a, 65b, is provided with a rear wheel servo valve 50 of rotary type and a rear wheel power cylinder (not shown). While a steering characteristic giving mechanism 30, constituted of a driven rotary member 32 connected to input and output shafts 31, 51 and an interlocking mechanism 35 interposed between both the input shaft 31 and the driven rotary member 32, is provided. Here the driven rotary member 32 of the steering characteristic giving mechanism 30 is eccentrically arranged for the input shaft 31, and a circular arc surface 33 is formed in a protrusion part 38 provided in the input shaft 31, while a protruding part 39, in which an engaging position with the circular arc surface 33 is changed in accordance with a rotary angle of the input shaft 31 in a condition that the driven rotary member 32 is placed in the neutral position, is provided in this driven rotary member 32.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention links a front wheel steering device and a rear wheel steering device via a transmission device to steer the front wheels according to the steering angle of the rear wheels. This invention relates to a four-wheel steering system.

(Prior art) As this type of four-wheel steering device, for example,
There is a technique disclosed in Japanese Patent No. 52578. Further, in such a four-wheel steering system, a rear wheel power steering device consisting of a rotary servo valve and a power cylinder is provided, and the input shaft of the rotary servo valve is connected to the front wheel steering device via a transmission device to steer the rear wheels. There are some that have been.

(Problems to be Solved by the Invention) In a four-wheel steering system, the rear wheel steering angle relative to the front wheel steering angle is held at 0 while the front wheel steering angle is small, for example, as shown in FIG. It is preferable to have a characteristic that increases in accordance with the front wheel steering angle when the front wheel steering angle increases. In a rear wheel power steering device in which a mechanism providing such steering characteristics is provided, for example, FIGS.
As shown in the figure, the rotation axis 01 of the input shaft 1, which is integrally provided with a pulley that rotates in conjunction with front wheel steering, and the rotation axis o2 of the driven rotation member 2 connected to the front side of the output shaft are made eccentric, and the driven rotation A follower 4 eccentrically provided on the member 2 is connected to the input shaft 1.
The first
As shown in FIG. 1, in the neutral position, it is conceivable to provide a considerably large backlash between the guide surface of the guide groove 3 and the follower 4.

According to such a device, the above-mentioned favorable characteristics can be obtained, but when a reverse input to steer the rear wheels from the ground side is applied in the front wheel steering neutral state, this reverse input is applied to the rear wheel steering device. When the value exceeds a predetermined value determined by the neutral return spring, the output shaft rotates freely until the follower 4 comes into contact with the guide surface of the engagement groove 3. Therefore, in order to increase the rigidity of the rear wheel against reverse input, the neutral The spring force of the return spring must be increased, which in turn requires an increase in the output of the power cylinder of the rear power steering system, or, if the rear wheel steering system does not use a power steering system, a handle added to the steering wheel. Torque increases.

The present invention provides a characteristic in which the rear wheel steering angle is maintained at 0 while the front wheel steering angle is small, and thereafter increases as the front wheel steering angle increases, and also increases the spring force of the neutral return spring. The purpose is to increase the rigidity of the rear wheels against reverse input.

(Means for Solving the Problems) For this purpose, the four-wheel steering device according to the present invention is provided in FIGS.
! As illustrated in FIG. 15 and FIGS. 7 to 9, a front wheel steering device 10 that steers the front wheels and a rear wheel steering device 20 that steers the rear wheels are provided. an input shaft 31 that rotates in conjunction with the operation;
A driven rotating member 3 connected to an output shaft 51 that steers the rear wheels
2, a four-wheel steering device comprising a steering characteristic imparting mechanism 30 comprising an interlocking mechanism 35 interposed between the input shaft 31 and the driven rotation member 32, wherein the driven rotation member 32 is connected to the input shaft 31; The interlocking mechanism 35 does not rotate the driven rotation member 32 from the neutral position while the rotation angle of the input shaft 31 is small, but the rotation angle of the input shaft If the rotation angle becomes large, the driven rotating member is rotated from the neutral position according to the rotation angle.

The input shaft 31 has a circular arc surface 3 centered on its axis of rotation.
3, and the driven rotation member 32 has a protrusion 39 whose engagement position with the arcuate surface 33 changes according to the rotation angle of the input shaft 31 when the driven rotation member is in the neutral position. The protruding portion 39 presses a portion of the circular arc surface 33 as the driven rotation member 32 rotates while the rotation angle of the input shaft 31 is small, and prevents the rotation of the driven rotation member 32. This is characterized in that when the rotation angle of the input shaft becomes large, the portion to be pressed moves out of the arcuate surface 33, allowing the driven rotating member to rotate.

In the four-wheel steering device of the present invention, instead of forming an arcuate surface 33 on the input shaft 31 as shown in FIG. , and instead of providing the protrusion 39 on the driven rotating member 32, the input shaft 31 has an engagement position with the arcuate surface 34 according to its rotation angle. A protrusion 38 that changes is provided,
While the rotation angle of the input shaft 3.1 is small, this projection 38 presses a part of the circular arc surface 34 as the driven rotation member 32 rotates, thereby preventing rotation of the driven rotation member. However, if the rotation angle of the input shaft becomes large, the portion to be pressed may be deviated from the arcuate surface 34, allowing the driven rotating member to rotate.

(Function) When the front wheel steering is in the neutral state, when the driven rotating member 32 attempts to rotate, the protruding portion 39 or the protruding portion 38 presses a part of the arcuate surface 33 or 34, so that the driven rotating member 32 cannot rotate. blocked. This prevents the rear wheels from receiving any reverse input from the ground to steer the rear wheels.

In the rear wheel steering neutral state, the centers of the arcuate surfaces 33 and 34 are both aligned with the axis of rotation of the input #31, so the input shaft 31 can freely rotate, and therefore the front wheels can also be freely steered. The rear wheel steering angle relative to the front wheel steering angle is determined by the interlocking mechanism 3.
5 and the rotation angle of the input shaft 31 becomes large, the driven rotation member 32 can be rotated, so that the front wheel steering angle is held at 0 while it is small, but when the front wheel steering angle is large. If so, it will increase according to the front wheel steering angle.

(Effects of the Invention) As described above, according to the present invention, the rear wheel steering angle is maintained at O while the front wheel steering angle is small, and thereafter the rear wheel steering angle increases as the front wheel steering angle increases. Moreover, when the front wheels are in neutral, the reverse input from the ground that acts on the rear wheels is stopped by the engagement of the circular arc surface with the protrusion or protrusion, so the rigidity against the reverse input from the ground on the rear wheels is reduced. can be increased.

(Example) First, a first embodiment shown in FIGS. 1 to 4 will be explained.

To explain the overall structure of the four-wheel steering device with reference to FIG. 2, the supply pump 6 driven by the engine 63 of the automobile
A predetermined amount of working fluid sucked in and sent out from the reservoir 62 by the flow dividing valve 61 is divided at a predetermined ratio, one of which is supplied to the front wheel steering device 10 and the other is supplied to the rear wheel steering device 20. , the used working fluid is returned to the reservoir 62.

The front wheel power steering device 10 includes a front wheel servo valve 11 provided on the front wheel operating rod 13 and a front wheel servo valve 11 provided in the middle of a handle shaft 16 that transmits rotation of the steering handle 15 to a rack and pinion mechanism 12 that converts rotation of the steering handle 15 into reciprocating motion of the front wheel operating rod 13. The main components are front wheel power cylinders 1 and 4. The front wheel servo valve 11 operates according to the steering wheel torque input from the steering wheel 15, and controls the supply and discharge of working fluid supplied to the left and right working chambers of the front wheel power cylinder 14 via the flow dividing valve 61. The amplified steering force is output to the front wheel operating rod 13, and the left and right front wheels 19 are steered via the tie rod 17 and knuckle arm 18 provided at both ends of the rod.

As shown in FIGS. 1 and 2, the rear wheel power steering device 20 includes a rotary type rear wheel servo valve 50 and a rear wheel power cylinder 24, and further includes a steering characteristic imparting mechanism 30 and an assist delay avoidance mechanism 40. ing. A pair of operating cables 65 with a cable length adjustment device 66 in the middle part
One end of the inner wires a and 65b connects to the front wheel operating iron 13.
The other end is wound around a pulley 31a formed on the input shaft 31 of the steering characteristic imparting mechanism 30.
The input shaft 31 is rotated in response to the steering of the driver 119, and the rear wheel servo valve 5o is operated via the steering characteristic imparting mechanism 30 and the assist delay avoidance mechanism 40. Both ends of each outer tube of the operation cables 65a, 65b are connected to the housing (
(not shown) and the housing 21.

The rear wheel power cylinder 24 includes a cylinder 25 formed in the housing 21 of the rear wheel power steering device 2o, and a piston 26 that is fluid-tightly fitted into the cylinder 25 and separates the inside thereof into left and right working chambers. Both ends of the rear wheel actuating rod 23 fixed to the piston 26 protrude from both ends of the cylinder 25 in a liquid-tight manner and slidably. Piston 2
A pair of return springs 26a for returning the rear wheel operating rod 23 to the illustrated neutral position are provided between both side surfaces of the cylinder 25 and the inner surfaces of both ends of the cylinder 25, and both ends of the rear wheel operating rod 23 are connected to a tie rod 27 and a knuckle arm 28. It is connected to the rear wheel 29 via.

As shown in FIGS. 1 and 3, the steering characteristic imparting device 413
0 is an interlocking mechanism consisting of an input shaft 31 and a driven rotating member 32, which are rotatably supported in the housing 21 around rotational axes ○1 and 02 that are eccentric from each other by a distance A, a guide groove 36, and a follower 37. 35, and a protrusion 38 and a protrusion 39 that engage with each other. Follower 3
Reference numeral 7 includes a support pin 37a fixed to the driven rotating member 32 eccentrically from the rotational axis 02 by a distance JIB, and a roller 37b rotatably supported by the support pin 37a. Further, the guide groove 36 is formed in a V-shape on the rear end surface of the input shaft 31, and in the neutral state of the front and rear wheels shown in the figure, the follower 37 is located at the top of the V-shaped guide groove 36, and the outer peripheral surface of the roller 37b is used as a guide. Although the roller 37b is separated from the guide surface of the groove 36, if the front wheel is steered beyond a certain level, the roller 37b will come into contact with the guide surface, and if the front wheel is further steered, the roller 37b will be engaged with the parallel portion of the guide groove 36 without play. It has become.

As shown in FIGS. 1 and 3, the input shaft 31 and the driven rotating member 32 have a protrusion 38 and a protrusion 39 that engage with each other.
are integrally formed, and these constitute the essential parts of the present invention. In the illustrated neutral state, the protrusion 38 and the protrusion 39 are aligned in the direction connecting the rotation axis 01.02, with the protrusion 38 being farther from the rotation axis 01. Projection 3
8 is formed with a concave arc surface 33 centered on the rotation axis o1, and the protrusion 39 is formed with an arc surface that fully engages with the arc surface 33 in the neutral state.

If the input shaft 31 rotates from the neutral state, the protrusion 38 rotates in the direction of the solid arrow in FIG. 3 about the rotation axis o1, so such rotation is free. However, when the driven rotating member 32 attempts to rotate from the neutral state, the protruding portion 39 rotates in the direction of the broken line arrow in FIG. 33a, but the protrusion 38 on which the arcuate surface 33 is formed does not escape in response to this pressure, so the driven rotating member 32
rotation is prevented.

As the input shaft 31 rotates in the direction of the solid line arrow from the front wheel steering neutral state, the arcuate surface 33 moves along the protrusion 39, the engagement length decreases, and the end 33a moves along the rotation axis 01. 02
When the projection 38 and the driven rotation member 32 reach the vicinity of the line connecting the rotation axis 02, the protrusion 38 and the driven rotation member 32 can rotate about the rotation axis 02.

In this state, the guide surface of the guide groove 36 is aligned with the roller 3.
The driven rotating member 32 starts to rotate when it starts contacting the outer circumferential surface of the rotating member 7b. As a result, the driven rotating member 32 rotates with the characteristics shown in FIG. 4 relative to the rotation angle of the input shaft 31.

As mainly shown in FIG. 1, the rear wheel servo valve 50 is provided in the housing 21 coaxially with the driven rotating member 32 of the steering characteristic imparting mechanism 30, with an assist delay avoidance mechanism 40, which will be described later, in between.

The output shaft 51 and the actuating shaft 52, which are coaxially rotatably supported in the housing 21, are elastically coupled by a torsion bar 56 so as to be relatively rotatable, and the binion 22 formed at the rear of the output shaft 51 is It meshes with a rack 23a formed on the rear wheel operating rod 23. The yoke 58, which is serrated and screwed to the front end of the operating shaft 52, is connected to the driven rotating member 3 via an assist delay avoidance mechanism 40, which will be described later.
It is connected to 2. The rear wheel servo valve 50 includes a rotor valve member 53 formed on a part of the operating shaft 52 and a sleeve valve member 54 connected to the output shaft 51 by a pin 55.
It is a boat throttle switching valve, and when the input torque applied to the operating shaft 52 is O and the relative rotation angle between the rotor valve member 53 and the sleeve valve member 54 is 0, the supply pump 6 is
The working flow supplied to the input capo 50a from the inlet port 50a is directly discharged from the discharge boat 50b to the reservoir 62. However, the input torque applied to the actuation 111152 increases, twisting the torsion bar 56 and causing both valve members 53.5
If a relative rotation occurs between the two distribution boats 50c and 50d, the working fluid supplied to the input port 50a is transferred to the rear wheel power from either of the two distribution boats 50c and 50d depending on the direction and rotation angle of the phase #4. The fluid is introduced into one working chamber of the cylinder 24, and the working fluid in the other working chamber is discharged from the other distribution boat to the reservoir 62 via the discharge boat 50b, thereby producing a rear flk steering assist force.

As shown in FIG. 1, the assist delay avoidance mechanism 40 includes an intermediate rotating member 41 and an output rotating member 42, which are supported by the housing 21 coaxially with the driven rotating member 32 and the rear wheel servo valve 50. The rotating member 42 is connected via a pin 58a so as to rotate together with the draft 58. A cylindrical Wl and second engagement bosses 44 and 45 are coaxially supported on the inner periphery of the driven and output rotating members 32 and 42,
A spiral spring 43 is wound around the outer periphery of each retaining boss 44,45. Each spiral spring 43 is in a state where initial torque is applied, and the inner end thereof is connected to each corresponding engagement boss 44.45.
Also, the outer end directly connects each rotating member 32, 41, 4
It is engaged with the inside and outside of 2. In this assist delay avoidance mechanism 40, when the transmitted torque between the driven and output rotating members 32, 42 is less than the initial torque of each spiral spring 43, that is, when it is normal, the rotation of the input rotating member 32 directly rotates the output. However, when the transmitted torque reaches its base, each spiral spring 43 is bent so that the rotation of the input rotating member 32 is no longer transmitted to the output rotating member 42.

Next, the overall operation of the first embodiment will be explained.

When the steering handle 15 is rotated clockwise as shown by the arrow in the jIZ diagram, the front wheel steering device 10 operates as described above, the front wheel operating iron 13 moves to the right as shown by the arrow, and the tie rod 17 and knuckle arm 18 are rotated. Through this, the left and right front wheels 19 are steered rightward. In response to this, the pulley 31a and input shaft 31 of the rear wheel steering device 20 are rotated in a counterclockwise direction when viewed from the rear via the operation cables 65a and 65b. If the steering wheel 15 is rotated counterclockwise in the opposite direction to the arrow, each part operates in the opposite direction to the above, and the front wheel 19 is steered to the left, and the pulley 31a and input shaft 3
1 is rotated in the clockwise direction when viewed from the back.

No matter which direction the input shaft 31 is rotated, the driven rotating member 32 does not rotate while the rotation angle of the input shaft 31 is small, as described above, and after that, the input shaft 31 does not rotate. It rotates in the same direction according to the Under normal conditions, the assist delay avoidance mechanism 40 does not operate, so the driven rotating member 32
The rotation is directly transmitted to the output rotating member 42 to operate the rear wheel servo valve 50, and the pinion 22 and rack 23a
to move the rear wheel operating rod 23 and tie rod 27.
and the rear wheel 29 via the knuckle arm 28.

The steering wheel is steered in a phase opposite to that of the front wheels 19, with characteristics as shown in the fJ4 diagram. At this time, the rear wheel servo valve 50 operates according to the transmission torque input to the operating shaft 52, and the rear wheel steering device 20 generates a steering assist force as described above.

When the steering angle of the front wheels 19 is O, if a large lateral reverse input is applied from the ground side, the rear wheels 29 will tend to be steered, and the output shaft 51 will be rotated via the rear wheel operating rod 23. shall be. However, the operating shaft 5
As described above, the driven rotating member 32 connected to the output shaft 51 is prevented from rotating due to the engagement between the protrusion 38 and the protrusion 39 in the front wheel steering neutral state. Then, the rear wheel servo valve 5o is activated, thereby generating an assist force in the rear wheel power cylinder 24 to counter the above-mentioned reverse input. Therefore, the reverse input that acts on the rear wheel 11129 from the ground when the front wheels are in neutral is not received by the rear wheel power cylinder 24 in addition to the return spring 26a, so there is no need to increase the spring force of the return spring 26a. The rigidity of the wheels 29 becomes sufficiently large, and there is no need to increase the output of the rear wheel power cylinders 24.

Next, the second embodiment shown in FIG. 5 is the same as the first embodiment except that the shape of the protrusion 39 that engages with the arcuate surface 33 of the protrusion 38 is cylindrical. Input shaft 31 from neutral position
The rotation of the driven rotating member 32 is free as in the first embodiment, but the rotation of the driven rotating member 32 is prevented by the projection 39 pressing the intermediate portion of the arcuate surface 33. When the input shaft 31 rotates and the end portion 33a reaches near the line connecting the rotational axes 01 and 02, the driven rotating member 32 becomes able to rotate in the same direction as the input shaft 31, and almost at the same time, the interlocking mechanism 35 The driven rotation member 32 starts rotating.

In the third embodiment shown in FIG.
A convex arcuate surface 34 centered on the rotational axis 01 is formed on the protrusion 39 provided at the steering neutral position of the driven rotating member 32, and the plane formed on the rotational axis 01 side of the protrusion 38 is in contact with the arcuate surface 34. ing. At the neutral steering position of the driven rotation member 32, the input shaft 31 can freely rotate. However, near the neutral position of the input shaft 31, the driven rotating member 3
2 is prevented by the protrusion 38 pressing the middle part of the arcuate surface 34. The input shaft 31 rotates and the protrusion 3
The end portion 38a of 01.8 is the axis of rotation 01.8. 02, the driven rotating member 32 becomes rotatable in the same direction as the input shaft 31, and almost at the same time, the driven rotating member 32 starts rotating by the interlocking mechanism 35.

Next, a fourth embodiment shown in FIGS. 7 to 9 will be explained.

This fourth embodiment differs from the previous embodiments only in the steering characteristic imparting device n30. As shown in FIGS. 8 and 9, the guide groove 36 of the interlocking mechanism 35 is composed of a central groove part 36a and a pair of outer groove parts 36b, and a protrusion part consisting of a support pin 37a and a roller 37b similar to the follower 37. 39
(which also fulfills the function of the follower 37 in the first embodiment) is movably engaged in the guide groove 36. Central groove 36
The outer circumferential surface of a is an arcuate surface 33 centered on the rotational axis 01 of the input shaft 31, and can engage with the portion of the outer circumferential surface of the roller 37b of the protrusion 38 that is farthest from the rotational axis 02. As shown in FIG.
They are arranged symmetrically from both ends of a in an inverted C-shape. Each outer groove portion 36b has a substantially constant width, and the outer circumferential surface of the roller 37b of the protruding portion 39 can be engaged between the two guide surfaces thereof without a substantial gap.

In the front and rear wheel steering neutral state, as shown in FIGS. 8 and 9, the protrusion 39 is located exactly at the center of the central groove 36a and engages with the arcuate surface 33. Since the center of the arc surface 33 coincides with the rotation axis 01 of the input shaft 31, the input shaft 31 can freely rotate from this state. However, since the rotation axis 02 of the driven rotation member 32 provided with the protrusion 39 is farther from the circular arc surface 33 than the rotation axis 01, if the driven rotation member 32 tries to rotate, the roller 37b of the protrusion 38 The trajectory C of the portion of the outer peripheral surface farthest from the rotation axis 02 attempts to enter the input shaft 31 from the circular arc surface 33 as shown in FIG. Therefore, even if an attempt is made to rotate the driven rotation member 32 in the front wheel steering neutral state, the protrusion 39 presses the arcuate surface 33, so that rotation of the driven rotation member 32 is prevented.

When the input shaft 31 rotates from the front wheel steering neutral state, the protrusion 3
The outermost end of 9 moves along the arcuate surface 33 and moves along the arcuate surface 33.
If it is removed, the driven rotation member 32 becomes rotatable. The input shaft 31 rotates further, and the protruding portion 39 moves along the two-dot chain line 3 in FIG.
When the position indicated by 9A is reached, the guide surface of the guide groove 36 comes into contact with the outer peripheral surface of the roller 37b, and the driven rotating member 32 comes to rotate. As a result, the driven rotating member 32 is connected to the input shaft 3.
For a rotation angle of 1, it rotates with characteristics similar to those shown in Fig. 4.

The rest of the structure and operation of the fourth embodiment are the same as those of the first embodiment, so corresponding parts are designated by the same reference numerals and detailed explanations will be omitted.

In each of the above embodiments, when the rear wheel 29 falls into a groove or the like and its steering is blocked, if force is applied to the steering wheel 15 and the steering wheel 15 is rotated significantly, the front and rear power steering devices 10
．． Although the transmission torque between 20 and 20 tends to increase, this transmission torque does not exceed a predetermined value due to the operation of the assist delay avoidance mechanism 40, so each operation cable 65a,
There is no risk of stretching or breaking 65b due to excessive force.

[Brief explanation of drawings]

1 to 4 show a first embodiment of a four-wheel steering device according to the present invention, FIG. 1 is a longitudinal sectional view of the main parts of the rear wheel power steering device, FIG. 2 is a schematic plan view of the whole, Figure 3 is the ■− of Figure 1.
(2) Cross-sectional view and FIG. 4 are diagrams showing operating characteristics. Fig. 5 is a diagram corresponding to Fig. 3 of the second embodiment, and Fig. 6 is a diagram corresponding to Fig. 3 of the third embodiment.
It is a figure equivalent figure. 7 to 9 show the fourth embodiment,
FIG. 7 is a vertical view of the main part of the rear wheel power steering device, FIG. 8 is a cross-sectional view taken along the line ■-■ in FIG. 7, and FIG. 9 is a detailed view showing the vicinity of the central groove portion of the guide groove. 10 and 11 show an example of a steering characteristic imparting mechanism different from the present invention, with FIG. 10 being a longitudinal plan view and FIG. 11 being a χI-XI side view of FIG. 10. Explanation of symbols 10... Front wheel steering device, 20... Rear wheel steering device, 30... Steering characteristic imparting mechanism, 31... Input shaft, 32
...Followed rotating member, 33.34...Circular surface, 35.
...Interlocking mechanism, 38...Protrusion, 39...Protrusion, 5
1...Output shaft.

Claims (2)

[Claims] (1) A front wheel steering device that steers the front wheels and a rear wheel steering device that steers the rear wheels are provided, and the rear wheel steering device includes an input shaft that rotates in conjunction with the operation of the front wheel steering device, and a rear wheel steering device that steers the rear wheels. A four-wheel steering device comprising a driven rotating member connected to an output shaft for steering, and a steering characteristic imparting mechanism comprising an interlocking mechanism interposed between the input shaft and the driven rotating member,
The driven rotating member is arranged to face the input shaft in the axial direction and to be eccentric to each other, and the interlocking mechanism does not rotate the driven rotating member from the neutral position while the rotation angle of the input shaft is small. When the rotation angle of the input shaft becomes large, the driven rotating member is rotated from a neutral position according to the rotation angle, and the input shaft is formed with an arcuate surface centered on its rotation axis, The driven rotation member is provided with a protrusion whose engagement position with the arcuate surface changes depending on the rotation angle of the input shaft when the driven rotation member is in the neutral position, and the protrusion is arranged in the input shaft. While the rotation angle of the input shaft is small, the rotation of the driven rotation member presses a part of the circular arc surface to prevent rotation of the driven rotation member, but as the rotation angle of the input shaft becomes large, this A four-wheel steering device characterized in that a portion to be pressed deviates from the circular arc surface to enable rotation of the driven rotating member. (2) A front wheel steering device that steers the front wheels, and a rear wheel steering device that steers the rear wheels, and the rear wheel steering device includes an input shaft that rotates in conjunction with the operation of the front wheel steering device, and a rear wheel steering device that steers the rear wheels. A four-wheel steering device comprising a driven rotating member connected to an output shaft for steering, and a steering characteristic imparting mechanism comprising an interlocking mechanism interposed between the input shaft and the driven rotating member,
The driven rotating member is arranged to face the input shaft in the axial direction and to be eccentric to each other, and the interlocking mechanism does not rotate the driven rotating member from the neutral position while the rotation angle of the input shaft is small. When the rotation angle of the input shaft becomes large, the driven rotation member is rotated from the neutral position according to the rotation angle, and the driven rotation member has the above-mentioned rotation angle when the driven rotation member is in the neutral position. An arcuate surface is formed around the rotational axis of the input shaft, and the input shaft is provided with a protrusion whose engagement position with the arcuate surface changes depending on the rotation angle of the input shaft. While the rotation angle of the input shaft is small, a part of the circular arc surface is pressed as the driven rotation member rotates to prevent the rotation of the driven rotation member, but when the rotation angle of the input shaft becomes large, A four-wheel steering device characterized in that the portion to be pressed deviates from the circular arc surface to enable rotation of the driven rotating member.