JPS63134379A - Rear wheel steering device for front and rear wheel steering car - Google Patents

Abstract

PURPOSE:To enable proper setting of axial displacement produced by rotztion of a conical shaft, by a method wherein a feed amount by a feed mechanism is set to a proper value, and the inclination angle of the pin part of the conical crank shaft is set to a proper value. CONSTITUTION:A coupling mechanism A of a rear wheel steering device is provided with an input shaft 41, a conical crank shaft 42, a shaft feed mechanism D, an axial feed mechanism D, a coupling body 43, and a rotor 44. The input shaft 41 is rotatably and unmovably mounted in a housing through a pair of bearings 51 and 52, and is coupled to a drive shaft through a spline formed to the tip of the input shaft. The tip of the conical crank shaft 42 is integrally rotatably and slidably coupled internally of a rear end cylinder part 41a through a ball spline 45. The conical crank shaft 42 is provided in the middle with a pin 42a inclined at a set angle theta with an axis L1, and is assembled at a rear end 42b to the housing through the axial feed mechanism D.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rear wheel steering device for a front and rear wheel steered vehicle capable of steering the rear wheels of the vehicle in conjunction with the steering operation of the front wheels.

[Prior art]

In this type of rear wheel steering device, a rotating shaft that rotates in response to a front wheel steering operation is connected to an operating rod of a rear wheel side steering link mechanism, and the operating rod is moved in the axial direction in response to rotation of the rotating shaft. Conventionally, there has been a device equipped with a coupling mechanism that steers the rear wheels to the same phase side when the front wheels have a small steering angle and to the opposite phase side when the front wheels have a large steering angle. This is proposed in JP-A-61-9374.

However, in the device proposed in the same publication,
The coupling mechanism includes an input shaft that is rotatably assembled to a housing that is assembled to a vehicle body, is connected to the rotation shaft, has an eccentric shaft at a rear end, and is rotated by the rotation shaft; a cylindrical member rotatably assembled on an eccentric shaft and integrally equipped with a pinion at the front and an eccentric cam at the rear;
an internal gear fixed to the housing and meshed with the pinion; and an internal gear rotatably assembled on the eccentric cam of the cylindrical member and slidably guided in the vertical direction by a guide member provided at the operating port. It is configured to include a slider that transmits the movement of the eccentric cam to the actuating rod as a displacement in the axial direction. Therefore, in this device, the two movements of revolution and rotation of the eccentric cam are combined by the rotation of the input shaft and transmitted to the slider, and from the slider to the actuating rod, the left-right movement of the combined movement is transmitted to the slider. Only that signal is transmitted and the rear wheels are steered.

[Problem that the invention seeks to solve]

By the way, in the conventional device described above, by various combinations of the tooth ratio of the pinion and internal gear and the amount of eccentricity of the eccentric cam, the rear wheel rotation is adjusted to the front wheel steering angle corresponding to the characteristics of the vehicle, which differs depending on the vehicle type. Although it is possible to set the steering angle (input-output characteristics), there are restrictions on manufacturing gears such as modules when setting the gear ratio, so it is not possible to set it steplessly within a limited space. Not only is it difficult to set the optimal rear wheel steering angle that matches the characteristics of the vehicle within a limited space, but also when the two values of the gear ratio and eccentricity are determined, Since the entire input-output characteristic is inevitably determined, it is not possible to appropriately change only a part of the doujin-output characteristic, for example, the characteristic at a small steering angle of the front wheels (or at a large steering angle). It is not possible to optimize the input-output characteristics of the

[Means for solving problems]

In order to solve this problem, the present invention provides the above-mentioned rear wheel steering device for a front and rear wheel steered vehicle, in which the coupling mechanism is rotatably and axially movably assembled to the housing via a shaft feeding mechanism. a conical crankshaft that is connected to the rotating shaft and has a pin part inclined at a set angle with respect to the axis in the intermediate part and is moved in the axial direction by the shaft feeding mechanism; and a conical crankshaft that is rotatable on the pin part of the conical crankshaft. It has a rod part that is attached to the conical crankshaft and extends in the radial direction of the bottle part, and the rod part is connected to the actuating rod via a conversion mechanism, and is oscillated by the rotation of the conical crankshaft to rotate the actuating rod. The structure includes a connecting body that is displaced in the axial direction, and the shaft feeding mechanism has a feed amount per unit angle within a specific rotation angle of the conical crankshaft that is different from a feed amount per unit angle at other rotation angles. Adopts an axis feed mechanism that allows

[Action of the invention]

In the rear wheel steering device according to the present invention, when the rotating shaft rotates in accordance with the steering when the front wheels are steered, the conical crankshaft is rotated by the rotating shaft and simultaneously moved in the axial direction by the shaft feeding mechanism. Therefore, the connecting body assembled on the pin part of the conical crankshaft swings in accordance with the rotation of the conical crankshaft, and also moves in the axial direction in accordance with the axial movement of the conical crankshaft. The two movements, rocking and axial movement, are combined and transmitted to the actuating rod via the conversion mechanism. Therefore, the actuating rod is displaced in its axial direction according to the above-mentioned combined movement,
When the front wheels have a small steering angle, the rear wheels are steered to the same phase side, and when the front wheels have a large steering angle, the rear wheels are steered to the opposite phase side.

Therefore, in the rear wheel steering device according to the present invention, by appropriately setting the feed amount by the shaft feed mechanism and appropriately setting the inclination angle of the bin portion on the conical crankshaft, it is possible to obtain an advantage by rotating the conical crankshaft. The axial displacement of the actuating rod can be set appropriately, and the rear wheel steering angle relative to the front wheel steering angle can be set in accordance with the characteristics of different vehicles depending on the type of vehicle.

〔Effect of the invention〕

By the way, in the rear wheel steering device according to the present invention, the feed amount by the shaft feed mechanism and the inclination angle of the bin part of the conical crankshaft can be adjusted without being subject to any manufacturing restrictions even within a limited space. Since each can be set steplessly as appropriate, it is possible to extremely easily set the optimum rear wheel steering angle within a limited space to suit the characteristics of different vehicles.

Further, in the rear wheel steering device according to the present invention, the shaft feed mechanism may have a feed amount per unit angle within a specific rotation angle of the conical crankshaft that is different from a feed amount per unit angle at other rotation angles. Since a shaft feed mechanism is adopted that can change the amount of feed in a specific part of the shaft feed mechanism, it is possible to change the feed amount in a specific part as appropriate, thereby improving the input-output characteristics obtained in the rear wheel steering system. can be optimized to suit the characteristics of the vehicle.

〔Example〕 Embodiments of the present invention will be described below based on the drawings.

1 to 8 show a first embodiment of a rear wheel steering device according to the present invention, and FIG. 5 schematically shows a front and rear wheel steered vehicle equipped with a rear wheel steering device according to the present invention. . In the vehicle shown in FIG. 5, the front wheel side steering link mechanism 10
Rank par 11 that makes up the steering wheel WS
It is displaced in the left and right direction by the operation of
It is connected via tie rods 14 and 15 to knuckle arms 12 and 13 that give a steering angle to the steering angle. In addition, rank par 11. Knuckle arm 2.13. Tie rod 14/1
A pole joint is interposed in each connection portion of 5. Further, the rear wheel steering device is connected to the rank par 11 via a rotating shaft 20.

The rotating shaft 20 is 1.1 in the pair of front and rear main shafts 219.
It is divided into four shafts: a shaft 22, 23 and a pinion shaft 24, and the main shaft 21 is connected to the rack par 11 via an intermediate shaft 22 and a pinion shaft 24. The main shaft 21 is rotatably supported by the vehicle body and extends a predetermined length from the front of the vehicle body toward the rear. Note that the number of divisions of the rotating shaft 20 can be changed as appropriate.

As shown in FIGS. 1 to 5, the rear wheel steering device includes a connecting mechanism A that connects the rotating shaft 20 and the operating rod 30, a link mechanism B that connects the rain rear wheel WR, and a connecting mechanism A. A power steering mechanism C is provided which connects the link mechanism B and assists in the force transmitted from the link mechanism A to the link mechanism B.

The coupling mechanism A includes an input shaft 41. which is attached to a housing H which is attached to the vehicle body. Conical crankshaft 42. It includes a shaft feeding mechanism, a connecting body 43, and a rotor 44. The input shaft 41 is connected to the housing H by a pair of bearings 51 and 52.
rotatably and axially immovably assembled,
The tip of the conical crankshaft 42 is connected to the intermediate shaft 23 of the rotary shaft 20 so as to be able to rotate together with the intermediate shaft 23, and the tip of the conical crankshaft 42 is connected to the intermediate shaft 23 of the rotating shaft 20 through a ball spline 45 within the rear cylindrical portion 41a so as to be able to rotate together and slide in the axial direction. Possibly connected.

Note that the ball spline 45 is a known one, and thereby the sliding resistance in the axial direction between the input shaft 41 and the conical crankshaft 42 is reduced. It has a pin portion 42a inclined at a set angle θ, and is assembled to the housing H at its rear end 42b via an axial feed mechanism, so that it can rotate relative to the housing H and move in the axial direction. ing. The shaft feeding mechanism is a mechanism that moves the conical crankshaft 42 in the axial direction at a predetermined feed amount when the conical crankshaft 42 rotates.
It is composed of a protruding pin 42c formed on the outer periphery of the rear end shaft portion, and a guide member 46 that is fixed to the housing H and has a spiral groove 46a on the inner periphery into which the protruding pin 42c is slidably fitted.

The first set value of the groove 46a is the lead of the portion where the protruding pin 42c engages when the conical crankshaft 42 rotates approximately 90 degrees to the left or right from the neutral position shown in the figure, and the lead of the portion where the protruding pin 42c engages when the conical crankshaft 42 rotates approximately 90 degrees left or right from the neutral position shown in the figure. Set the lead of the part where the protruding pin 42C engages when rotating to a second set value (smaller than the first set value)
When the conical crankshaft 42 rotates approximately 90 degrees to the left or right, the feed amount per unit rotation angle is '9'.
The feed amount per unit rotation angle when rotating by 0 degrees or more is set larger (see the two-dot chain line in FIG. 8).

In this embodiment, as is clear from FIG. 5, since the intermediate shaft 20 rotates in the same direction as the steering wheel WS, the spiral direction of the groove 46a is directed to the left. If the intermediate shaft 20 is configured to rotate in the opposite direction to the steering wheel WS, the spiral direction of the groove 46a needs to be in the right direction.

The connecting body 43 is connected to the pin portion 42a of the conical crankshaft 42.
A rod portion 43 is rotatably assembled on the top via a pair of bearings 53 and 54 and extends in the radial direction of the pin portion 42a.
a, and the ball bearing 4 is connected to this rod portion 43a.
It is connected to the rotor 44 via 7. The ball bearing 47 is slidably fitted onto the rod portion 43a and is tiltably assembled within a spherical mounting hole 44a provided in the rotor 44. The rotor 44 has four bolts 44C
Members 44A, 44 that can be divided into upper and lower halves connected by
B, is rotatably assembled to the housing H via a pair of bearings 55 and 56, and has sector teeth 44b that mesh with rack teeth 30a formed on one side of the actuating rod 30. There is. In addition, both bearings 55.56
The looseness is caused by the holder Ha attached to the housing H (
This can be eliminated by advancing the lock nut (fixed by a lock nut Hb).

Therefore, in the above-mentioned coupling mechanism A, ■the input shaft 4
1 is assembled via a ball spline 45 to a conical crankshaft 42, and a connecting body 4 is attached via bearings 53 and 54.
3 and the guide member 46 is also assembled.

■ Spherical mounting hole 44 provided in the upper member 44A of the rotor 44
Assemble the ball bearing 47 to a.

■The one assembled in above ■ and the one assembled in above ■,
The rod portion 43a of the connecting body 43 is fitted into the ball bearing 47 while being combined.

(2) The lower member 44B is coupled to the upper member 44A of the rotor 44 with a bolt 44C so that the shaft portions supported by bearings 55 and 56 are coaxial.

■The bearing 52 assembled in the steps up to ■ above.
and the actuating wand 30, etc., are assembled into the housing H in advance.

(2) After the bearing 56 is assembled and fixed with a snap ring, the bearing 55 is assembled and temporarily tightened with the holder Ha.

■Install the bearing 51 and secure it with a snap ring.

(2) Assemble the rear cover Hc onto the guide member 46 in the neutral position, connect the rear cover He and the guide member 46 with the bolts Hd, and connect the rear cover Hc to the housing H with the ports He.

■Finally, fix the holder Ha with the lock nut Hb and attach the cap Hf to the housing H.

Conical crankshaft 42. Connector 43
．． Rotor 44. Each member such as the guide member 46 is assembled within the housing H.

The link mechanism B, as shown in FIGS. 3 and 5,
An operating rod 30, a relay rod 71 provided through the operating rod 30, and tylon doors 2.73 connected to both left and right ends of the relay rod 71 via ball joints.
It is composed of knuckle arms 74.75 connected to each tie rod 72.73 via ball joints, and the rear rain wheel WR is steered by displacement of the knuckle arms 74.75 in the left and right direction. ing.

In addition, each end of the housing H and each tie rod 72°73
The insides of the boots 76 and 77, both ends of which are fixed to the ends of the relay rods 76 and 77, are connected by pipes 78 so that the left and right movement of the relay rod 71 is not inhibited.

The relay rod 71 includes a tenth lead 71A that passes through the actuating rod 30 and has both ends protruding from the actuating rod 30, and a second lead that is screwed to both left and right ends of the tenth lead 71A.
0nd 71B and 30th 71C, and each Rondo 1B
, 71C lock nuts 71D, 71 to fix the cape content.
E, the length can be adjusted, and the bearing bush 6 assembled to the housing H.
1.62 so as to be slidable in the axial direction. A socket 71b1 that forms a ball joint with the spherical end 73a of the tie rod 73 is integrally formed at the outer end of the 20th node 71B. Further, a spring 31 and a pair of left and right flanged sleeves 32.33 are interposed between the relay rod 71 and the actuator 07130, and the relative axial movement of both rods 30.71 is elastically transmitted by a predetermined amount. It is supposed to be done.

The power steering mechanism C assists the force transmitted from the operating rod 30 to the relay rod 71, and the power steering mechanism C
1, a power cylinder C2, etc. The control valve C1 is a spool type control valve, and the operating rod 30
A valve sleeve 34 is fitted and fixed therein, and a valve spool 71a formed in a part of the tenth node 71A of the relay rod 71 is provided, and a supply port 71a2 formed in the valve spool 71a1 is connected to the tenth node 71A. The valve spool 71 is connected to the inflow boat 71b3 provided in the 20th node 71B through a through hole (not shown) provided in the 20th node 71B and a through hole 71b2 provided in the 20th node 71B.
Both discharge boats 71a3 formed at a1 are connected to the 10th node 7.
1A, a through hole (not shown) provided parallel to and separate from the through hole, and a through hole 71a4 extending radially outward from the end of the through hole.
and the second through the through hole 71b4 provided in the 20th node 71B.
It communicates with an outflow port 71b5 provided in the ground 71B. Note that the inflow port 1-71b3 is connected to the hydraulic pump P, and the outflow port 71b5 is connected to the reservoir T.

On the other hand, the power cylinder C2 includes a cylinder body Hg constructed using a part of the housing H, and a cylinder body Hg constructed using a part of the housing H.
A pair of left and right oil chambers R1 are fitted into the interior so as to be slidable in the axial direction.
, R2, and the piston 71C1 is fixed onto the 30th node 71C of the relay rod 71. The oil chamber R1 on the left side of FIG.
The oil chamber R2 on the right side in FIG.
The through hole 71C4 provided in C and the through hole 7 provided in the 10th side 71A
3 (right side bow) 7 formed in the valve spool 7lal through a through hole 71a7 provided parallel to and separated from 1a5.
It is connected to 1a8.

In this embodiment configured as described above, when the steering wheel WS is rotated, the rack par 11 is displaced in the left-right direction and the front wheels WF are steered. During this steering, the rotary shaft 20 is rotated by the rack bar 11, the input shaft 41 in the coupling mechanism A is rotated, and the rear and rear rank shafts 42 are rotated and simultaneously moved in the axial direction by the shaft feeding mechanism. For this reason, the connecting body 43 assembled on the pin portion 42a of the conical crankshaft 42 is (when rotating)
As illustrated in FIG. The two movements are combined and transmitted to the actuating rod 30 via the ball bearing 47 and rotor 44. Therefore, the actuating rod 30 moves in the axial direction in response to the above-mentioned combined movement by an amount shown by the solid line in FIG. and the amount of movement obtained by the axial movement of the connecting body 43 shown by the two-dot chain line), and when the front wheel WF has a small steering angle, it moves to the same phase side to a small extent, and the front wheel WF When the steering angle is large, the rear wheels WR are largely steered to the opposite phase side. Note that the movement of the actuation rod 30 is transmitted to the relay rod 71 via the spring 31 etc.
In order to cause the power cylinder mechanism C to operate, the rear wheel WR is steered while being assisted by the power cylinder mechanism C.

Therefore, in this embodiment, the feed amount by the shaft feed mechanism (determined by the lead of the spiral groove 46a) is set appropriately, and the inclination angle θ of the pin portion 42a on the conical crankshaft 42 is adjusted. By setting the appropriate settings, the displacement in the axial direction of the actuating rod 30 obtained by the rotation of the conical crankshaft 42 can be set appropriately, and the rear wheel turning angle relative to the front wheel turning angle can be adjusted to match the characteristics of the vehicle, which vary depending on the vehicle type. can be set.

By the way, in this embodiment, the feed amount by the above-mentioned shaft feed mechanism and the inclination angle θ of the pin portion 42a of the conical crankshaft 42 can be adjusted without being subject to manufacturing restrictions even within a limited space. Since each can be set steplessly as appropriate, it is possible to extremely easily set the optimum rear wheel steering angle within a limited space to suit the characteristics of different vehicles.

Further, in this embodiment, a protruding pin 42c formed on the conical crankshaft 42 and a spiral groove 46a into which the protruding pin 42c is slidably fitted are used as a shaft feeding mechanism for moving the conical crankshaft 42 in the axial direction during rotation. A shaft having a guide member 46 having a feed amount per unit rotation angle when the conical crankshaft 42 rotates approximately 90 degrees to the left or right is larger than the feed amount per unit rotation angle when the conical crankshaft 42 rotates by 90 degrees or more. Since the feed mechanism is adopted, the amount of axial displacement of the operating rod 30 obtained by rotating the conical crankshaft 42 by a small angle from the neutral position, that is, when the front wheel WF is at a small steering angle, the rear wheel WR moves to the same phase side. The amount of axial displacement of the actuating rod 30 obtained by appropriately suppressing the steered angle and rotating the conical crankshaft 42 by a large angle from the neutral position, that is, when the front wheel WF is at a large steering angle, the rear wheel WR The input-output characteristics (conical crankshaft 42
The relationship between the rotation angle of the actuating rod 30 and the axial displacement amount of the actuating rod 30 can be optimized to match the characteristics of the vehicle as shown by the solid line in FIG.

In this embodiment, since the power steering mechanism C is disposed closer to the rear wheel WR than the coupling mechanism A, when the relay rod 71 is pushed in the axial direction by an external force from the rear wheel WR, the control valve C1 is closed. The power cylinder C2 is operated so as to generate a force opposing the external force. Therefore, the external force is canceled and the rear wheel steering device is not operated by the external force.

FIG. 9 shows a second embodiment of the rear wheel steering device according to the present invention. In this embodiment, the shaft feed 1 and by a pin 48 that penetrates a hole provided in a guide member 46 that is fixed to the housing H and supports the conical crankshaft 42 rotatably and slidably in the axial direction and is slidably fitted into the groove 42d. It is configured. Groove 42
The first set value of d is the lead of the portion where the pin 48 engages when the conical crankshaft 42 rotates approximately 90 degrees to the left or right from the neutral position shown, and also rotates more than 90 degrees to the left or right. The lead of the part where the pin 48 engages is set to a second set value (smaller than the first set value), and the lead per unit rotation angle when the conical crankshaft 42 rotates approximately 90 degrees to the left or right. The feed amount is set larger than the feed amount per unit rotation angle when rotating by 90 degrees or more.

The rest of the configuration is the same as that of the first embodiment, so the explanation thereof will be omitted. Furthermore, since the operation of this second embodiment is substantially the same as that of the first embodiment, a description thereof will be omitted.

In addition, in this second embodiment, since the spiral groove 42d is formed on the outer periphery of the conical crankshaft 42,
Compared to the case of the first embodiment described above, it is easier to make the shape of the groove 42d more complicated.

Therefore, it is possible to easily change the lead of the helical groove 42d every 45 degrees of the conical crankshaft 42 to obtain more optimal input-output characteristics than in the first embodiment.

FIG. 10 shows a third embodiment of the rear wheel steering device according to the present invention, and in this embodiment, the shaft feed mechanism operates a ball screw mechanism D1 and a ball nut 49 in the ball screw mechanism DI. It is constituted by an electric motor M for rotation. The ball screw mechanism D1 is a shaft feeding mechanism that moves the conical crankshaft 42 in the axial direction at a constant feeding amount (a value corresponding to the first set value in both of the above embodiments) when the conical crankshaft 42 rotates. The threaded groove 42e formed on the outer periphery of the rear end shaft portion of the crankshaft 42 and the housing H are rotatably but immovably assembled in the axial direction via a pair of bearings 57 and 58, and are circulated and supplied to the threaded groove 42e inside. A worm wheel 49 is installed on the outer periphery of the central part to accommodate a large number of balls.
It is constituted by a pole nut 49 having a.

The electric motor M operates in response to the rotation of the conical crankshaft 42 to rotate the worm Ma that engages the worm wheel 49a. In this embodiment, the conical crankshaft 42 is rotated approximately 90 degrees from the neutral position. When it rotates, it stops, and when it rotates more than 90 degrees, it rotates in a direction that reduces the axial movement of the conical crankshaft 42 by a predetermined amount. The amount of feed in the axial direction is the same as in both of the above embodiments. The rest of the configuration is the same as the first embodiment, so
The explanation will be omitted. Furthermore, the operation of this third embodiment is as follows:
Since the operation is substantially the same as that of the first embodiment, a description thereof will be omitted.

In this third embodiment, since the operation of the electric motor M is controlled according to the rotation of the conical crankshaft 42, both of the above can be achieved by appropriately changing the operation control method of the electric motor M. Input-output characteristics that are difficult to obtain in the embodiments can also be easily obtained. In addition, when implementing this third embodiment, the pole nut 49
It is also possible to use a hydraulic cylinder instead of the electric motor M as the actuator for rotating the motor. When a hydraulic cylinder is employed, a pinion is formed on the outer periphery of the ball nut 49, and the pinion is rotated by a rack pushed by the hydraulic cylinder.

[Modified example]

In the above embodiment, the rotating shaft 20 that rotates in response to the steering operation of the front wheel WF is connected to the rack bar 11 of the front wheel side steering link mechanism, and is rotated by the axial movement of the rack bar 11. It is also possible to connect the rotary shaft 20 to a steering main shaft that is directly rotated by the steering wheel WS, so that the rotary shaft 20 is rotated by the steering main shaft.

In addition, in the above embodiment, the operating rod 30 and the relay rod 71 are configured as separate members to be movable relative to each other in the axial direction, and the power steering mechanism C is disposed coaxially with both rods 30 and 71. It is also possible to integrate the rods 30, 71 and eliminate the power steering mechanism C.

[Brief explanation of the drawing]

1 to 8 relate to a first embodiment of the rear wheel steering device according to the present invention, FIG. 1 is an enlarged longitudinal sectional side view taken along line 1-1 in FIG. 3, and FIG. 1 is a partially cutaway plan view of the part shown in FIG. 1, FIG. 3 is a longitudinal sectional front view of the rear wheel steering device, FIG. 4 is a plan view of the same, and FIG. 5 is an example of a vehicle equipped with the rear wheel steering device. A schematic plan view, FIGS. 6 and 7 are operational explanatory diagrams of the main parts of the rear wheel steering device, and FIG. 8 shows the rotation angle of the conical crankshaft and the axis of the operating rod obtained by the rear wheel steering device. FIG. 3 is a diagram showing a relationship between directional displacement amounts. Further, FIG. 9 is an enlarged longitudinal sectional side view of a main part showing a second embodiment of the rear wheel steering device according to the present invention, and FIG. 10 is an enlarged main part showing a third embodiment of the rear wheel steering device according to the present invention. FIG. Explanation of symbols 10... Front wheel side steering link mechanism, 20...
Rotating shaft, 30... Operating rod, 30a... Rank tooth, 42... Conical crankshaft, 42a... Pin portion, 42C... Protruding pin, 42d... Helical groove, 4
2e... Thread groove, 43... Connecting body, 43a... Rond part, 44... Rotor, 44b... Sector tooth, 4
6... Guide member, 46a... Spiral groove, 47...
...Ball bearing, 48...Pin, 49...Ball nut, A...Connection mechanism, B...Rear wheel side steering link mechanism, D...Shaft feed mechanism, Dl...Ball screw Mechanism, H...Housing, Ll...Axis of conical crankshaft, M...Electric motor (actuator)
, WS...Steering wheel, WF...Front wheel,
WR...Rear wheel.

Claims (4)

[Claims] (1) A rotating shaft that rotates in response to the steering operation of the front wheels is connected to an operating rod of the rear wheel side steering link mechanism, and the operating rod is displaced in its axial direction in accordance with the rotation of the rotating shaft, thereby steering the front wheels. A rear wheel steering device for a front and rear wheel steered vehicle comprising a coupling mechanism that steers the rear wheels to the same phase side when the steering angle is small and steers the rear wheels to the opposite phase side when the front wheels have a large steering angle. The mechanism is rotatably and axially movably assembled in the housing via a shaft feed mechanism, is connected to the rotating shaft, and has a pin portion inclined at a set angle with respect to the axis in an intermediate portion, and the shaft feed mechanism It has a conical crankshaft that is moved in the axial direction by a mechanism, and a rod part that is rotatably assembled on the pin part of the conical crankshaft and extends in the radial direction of the pin part, and the rod part is used to perform the operation. The structure includes a connecting body connected to the rod via a conversion mechanism and oscillated by the rotation of the conical crankshaft to displace the actuating rod in its axial direction, and as the shaft feeding mechanism, Rear wheel steering of a front and rear wheel steering vehicle, characterized in that a shaft feed mechanism is adopted that allows the amount of feed per unit angle within a rotation angle to be different from the amount of feed per unit angle at other rotation angles. Device. (2) The shaft feeding mechanism includes a protruding pin formed on the outer periphery of the shaft portion of the conical crankshaft, and a guide member that is fixed to the housing and has a spiral groove in the inner periphery into which the protruding pin is slidably fitted. The lead of the groove that the protruding pin engages when the conical crankshaft rotates from its neutral position to the set angle is a first set value, and the conical crankshaft rotates beyond the set angle. Claim 1, wherein the lead of the groove with which the protruding pin engages is set to a second set value when
The rear wheel steering device of the front and rear wheel steered vehicle described in 2. (3) The shaft feeding mechanism is constituted by a spiral groove formed on the outer periphery of the shaft portion of the conical crankshaft, and a pin fixed to the housing and slidably fitted into the groove; A lead of the groove that the pin engages when the conical crankshaft rotates from its neutral position to a set angle is a first set value, and the pin engages when the conical crankshaft rotates beyond the set angle. 2. A rear wheel steering device for a front and rear wheel steered vehicle according to claim 1, wherein the lead of said groove is set to a second set value. (4) The shaft feeding mechanism includes a threaded groove formed on the outer periphery of the shaft portion of the conical crankshaft, and a ball that is rotatably but immovably assembled in the housing and circulated and supplied to the threaded groove inside the housing. A ball screw mechanism comprising a ball nut accommodating the housing, and an actuator that is fixed to the housing and operates in response to rotation of the conical crankshaft to rotate the ball nut. The rear wheel steering device for the front and rear wheel steered vehicle according to item 1.