JPH0321337Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rear wheel steering device for a front and rear wheel steering vehicle capable of steering the rear wheels of the vehicle in conjunction with the steering operation of the front wheels, and particularly relates to a front wheel steering mechanism. a rotating shaft whose front end is coupled to the rotating shaft to rotate according to the front wheel steering of the mechanism; and a rear end of the rotary body to the rear wheel steering shaft of the rear wheel steering mechanism, which rotates according to the rotation of the rotating shaft. The present invention relates to a rear wheel steering device for a front and rear wheel steered vehicle, which includes a coupling mechanism that steers the rear wheels by displacing the rear wheel steering shaft in its axial direction.

[Prior art]

Conventionally, this type of technology, as shown in Japanese Unexamined Patent Publication No. 58-30869, has a rotating shaft whose front end is connected to a front wheel steering mechanism and rotates in accordance with the front wheel steering of the mechanism, and one end of the rotating shaft. a crank member coupled to the rear end of the rotating shaft and pivotally supported on the vehicle body; and a pair of guides provided perpendicularly to the rear wheel steering shaft of the rear wheel steering mechanism and slidably housing the other end of the crank member. The rotating shaft and the crank member are rotated in response to front wheel steering, and the rotational movement of the other end of the crank member is reciprocated in the axial direction of the rear wheel steering shaft by the sliding movement between the guide pieces at the other end. This is converted into motion, and the rear wheels connected to the rear wheel steering shaft are steered in accordance with the front wheel steering.

[Problem that the invention attempts to solve]

However, in the conventional device described above, the rotational motion of the other end of the crank member that rotates in response to front wheel steering is converted into reciprocating motion in the axial direction of the rear wheel steering shaft, so the rear wheel steering angle is It changes sinusoidally with the steering angle. For this purpose, the rear wheel steering angle is such that the rear wheels are steered in phase with the front wheels in a small or medium steering angle region of the front wheels, and the rear wheels are steered in the opposite phase to the front wheels in a large steering angle region of the front wheels. Since the characteristics are fixed, it is not possible to drive the vehicle with the rear wheel steering angle characteristics depending on the vehicle driving situation and the driver's intention. That is, when the vehicle travels on a gentle curve, the front wheel steering angle is small, so the rear wheels are steered in the same phase as the front wheels, making it difficult for the vehicle to rotate. In addition, even if the driver tries to reduce or increase the degree of influence of the front wheel steering angle on the rear wheel steering angle, for example, even if a driver who is unfamiliar with front and rear wheel rotationally steered vehicles tries to always keep the rear wheel steering angle to zero, the rear wheel steering angle will change. The steering angle is determined according to the rear wheel steering angle characteristics regardless of the driver's intention, and it may be difficult for the driver to drive the vehicle.

The purpose of the present invention is to improve the maneuverability of the vehicle by making it possible to change the characteristics of the rear wheel steering angle relative to the front wheel steering angle depending on the vehicle running conditions and the driver's intention. It is an object of the present invention to provide a rear wheel steering device for a front and rear wheel steered vehicle.

[Means for solving problems]

In order to solve this problem, the structural features of the present invention include a rotating shaft whose front end is connected to a front wheel steering mechanism and rotates in accordance with the front wheel steering of the mechanism, and a rear end of the rotating shaft that is connected to the rear wheels. Rear wheel steering of a front and rear wheel steered vehicle, comprising a coupling mechanism that is connected to a rear wheel steering shaft of the steering mechanism and steers the rear wheels by displacing the rear wheel steering shaft in its axial direction in accordance with rotation of the rotation shaft. In the device, the coupling mechanism is rotatably pivoted to a housing assembled to the vehicle body adjacent to the rear wheel steering shaft, and is perpendicular to the rear wheel steering shaft at a neutral position thereof. a swinging lever; a coupling means for coupling a swinging end of the swinging lever to the rear wheel steering shaft to convert the swinging motion of the lever into an axial movement of the rear wheel steering shaft; a rotary body having a guide groove and pivotally supported on the housing; a rotary drive means for directly or indirectly rotationally driving the rotary body in response to rotation of the rotary shaft; A pin that is slidably fitted into a groove and swings the swing lever in accordance with the rotation of the rotating body, and a pin movable mechanism that is assembled to the swing lever and moves the pin in the longitudinal direction of the lever. It's because it's configured.

[Effect]

In the present invention configured as described above, the rotating shaft rotates in response to front wheel steering, and this rotational force is transmitted to the rotating body to rotate the guide groove provided in the rotating body. As the guide groove rotates, the pin attached to the swing lever slides on the guide groove and swings the swing lever, and the swing movement of the swing lever is controlled by the coupling means in the axial direction of the rear wheel steering shaft. The rear wheels are steered in accordance with the front wheel steering. Also,
By moving the pin to a desired position in the longitudinal direction of the swing lever using the pin movable mechanism, the distance between the swing fulcrum of the lever and the pin position, which is the point of force, is changed, and the swing against the rotation of the rotating body is Since the swing amount or swing direction of the dynamic lever can be changed according to the pin position, the rear wheel steering angle characteristic relative to the front wheel steering angle can be changed to a desired characteristic, and the maneuverability of the vehicle can be improved. can.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 schematically shows a front and rear wheel steered vehicle to which the rear wheel steering device according to the present invention is applied.
This front and rear wheel steering vehicle includes a front wheel steering mechanism 10, a rear wheel steering mechanism 20, a rotating shaft 30 that rotates in accordance with front wheel steering of the front wheel steering mechanism 10, and a coupling mechanism 40 that connects the same shaft 30 to the rear wheel steering mechanism 20. It is equipped with

The front wheel steering mechanism 10 is displaced in the lateral direction of the vehicle body by the rotation of a pinion 13 connected to a steering handle 11 via a steering shaft 12, thereby steering the left and right front wheels 14a, 14b.
and a left tie rod 16a connected between the left end of the rack shaft 15 and the left front wheel 14a.
and a right tie rod 1 connected between the left knuckle arm 17a, the right end of the coaxial shaft 15, and the right front wheel 14b.
6b and a right knuckle arm 17b.
The rear wheel steering mechanism 20 includes a rear wheel steering shaft 22 that is displaced in the lateral direction of the vehicle body and steers the left and right rear wheels 21a, 21b.
and the left tie rod 23a and left knuckle arm 2 connected between the left end of the coaxial 22 and the left rear wheel 21a.
4a, a right tie rod 23b and a right knuckle arm 24b connected between the right end of the coaxial shaft 22 and the right rear wheel 21b. The rotating shaft 30 includes a main shaft 31 extending in the longitudinal direction of the vehicle body and rotatably supported by the vehicle body, and intermediate shafts 32 and 33 connected to the front and rear ends of the shaft 31, respectively.
and a pinion shaft 34 having a pinion portion meshing with the rack shaft 15 at the front end and connected to the intermediate shaft 32 at the rear end, and an input shaft of the coupling mechanism 40 connected to the intermediate shaft 33 by displacement of the rack shaft 15. Rotate 41.

As shown in FIGS. 1 and 2, the coupling mechanism 40 includes a housing 42 that is assembled to the vehicle body and accommodates an intermediate portion of the rear wheel steering shaft 22 so as to be movable in the axial direction.
An input shaft 41 is rotatably assembled to the housing 42 via bearings 50 and 51 and rotates in accordance with the rotation of the rotating shaft 30, and a bearing 54 is provided in the shaft hole 42a provided in the lower part of the housing 42 and the member 52. , 55, a swinging lever 44 rotatably mounted to the housing 42 via bearings 56, 57, and a swinging lever 44 that moves in its axial direction. The pin 4 can be assembled and stored in the guide groove 43b of the rotating body 43 via the frame 45a.
5.

A ball nut 46 that fits into a ball screw 41a formed on the coaxial shaft 41 is assembled into the intermediate portion of the bearings 50, 51 of the input shaft 41.
6 moves in the axial direction of the input shaft 41 in accordance with the rotation of the input shaft 41. Rack teeth 46a formed on the side surface of the ball nut 46 mesh with a sector gear 43c formed on the rotating body 43, and rotate the rotating body 43 about the shaft 43a in accordance with the movement of the input shaft 41 of the ball nut 46 in the axial direction. . A guide groove 43b is formed in the upper part of the rotating body 43 by a pair of guide pieces 43d and 43e extending in the longitudinal direction of the vehicle body when the rotating body 43 is in a neutral state.

The swinging lever 44 has a guide groove 44c formed by a pair of guide pieces 44a and 44b at its swinging end, and a pin 47 press-fitted into the rear wheel steering shaft 22 is slidably inserted into the guide groove 44c. It is accommodated. In addition,
The pin 47 has a flange 47a at its intermediate portion to adjust the protrusion length of the pin 47 from the rear wheel steering shaft 22. Further, the swing lever 44 rotatably supports a threaded shaft 48 extending in its longitudinal direction via bearings 58 and 59, and the threaded shaft 48
A pin 45 is screwed into the threaded portion, and the pin 45 is moved along a guide groove 44d extending in the longitudinal direction of the swing lever 44 as the shaft 48 rotates. The shaft 48 is rotated by a motor 60 rotating a shaft 49 of a bevel gear 49a meshed with a bevel gear 48a fixed to one end of the shaft 48.

The pin 45 attached to the swing lever 44 by a threaded shaft 48 is rotatably fitted into a box-shaped frame 45a at its lower part, and the frame 45a is slidable in the guide groove 43b. Same groove 43b and pin 45
It is interposed between.

In this embodiment configured as described above, when the vehicle is traveling straight, the vehicle is in the state shown in FIG.
4 is in the state shown in FIGS. 1 and 2.

First, the case shown in FIGS. 1 and 2 in which the pin 45 and the frame 45a are located forward of the center of rotation of the rotating body 43 will be described. When the steering wheel 11 is turned to the left (or right) while the vehicle is traveling straight, the rack shaft 15 is displaced to the right (or left) by the pinion 13, and the left and right tie rods 16a,
The left and right front wheels 14a and 14b are steered to the left (or right) via the left and right knuckle arms 16b and left and right knuckle arms 17a and 17b, respectively. At this time, the rotating shaft 30 is connected to the rack shaft 15.
The displacement to the right (or left) causes the input shaft 41 of the coupling mechanism 40 to rotate to the left (or right). This left (or right) rotation of the input shaft 41 causes the ball nut 46 to move forward (or backward), and the rotating body 43 to the right (or left).
Rotate. Due to this rotation, the distance between the swinging fulcrum of the swinging lever 44, the pin 45, and the frame 45a is kept constant, so that the frame 45a is connected to the guide groove 43b.
is displaced in the right (or left) direction while swinging in the circumferential direction of the rotating body 43. At this time, the pin 45 swings the swing lever 44 in the right (or left) direction while rotating within the frame 45a, so the pin 47 slides rearward within the guide groove 44c while the rear wheel steering shaft 22 to the right (or left) direction, and the left and right rear wheels 21a, 2
1b is steered to the left (or right) via left and right tie rods 23a, 23b and left and right knuckle arms 24a, 24b. As a result, the left and right rear wheels 21a, 2
1b is steered in the same phase as the left and right front wheels 14a and 14b.

Further, the rotation of the motor 60 is controlled by an electric control means (not shown) such as a microcomputer,
This rotation of the motor 60 rotates the threaded shaft 48 via the shaft 49 and bevel gears 49a, 48a, and moves the pin 45 forward along the guide groove 44d.
5 and the frame body 45a becomes larger, and the amount of displacement of the rear wheel steering shaft 22 with respect to the rotation angle of the rotating body 43 becomes larger than in the above case.
The steering angles of a and 21b become larger. Conversely, the motor 60 is controlled to rotate in the opposite direction to the above to rotate the pin 45.
When the frame body 45a is moved backward, the rotating body 43
The distance from the rotation center to the pin 45 and the frame 45a becomes smaller, and contrary to the above, the left and right rear wheels 21a,
The steering angle of 21b becomes smaller. And pin 45
When the frame body 45a is moved to the center of rotation of the rotating body 43, even if the rotating body 43 rotates, the frame body 45a and the guide groove 43b only rotate around the pin 45, and the swing lever 44 does not swing. Left and right rear wheels 21
The steering angles of the wheels a and 21b are always zero regardless of the steering of the left and right front wheels 14a and 14b.

On the other hand, when the steering handle 11 is rotated to the left (or right) with the pin 45 and the frame 45a further moved rearward due to the rotation of the threaded shaft 48, the rotating body is moved to the right (or right) in the same way as above. or left), and this rotation causes the frame 45a to move into the guide groove 43b.
is displaced in the left (or right) direction while sliding in the circumferential direction of the rotating body 43. As a result, the pin 45 causes the swing lever 44 to swing in the left (or right) direction, so the pin 47 and the guide groove 44c displace the rear wheel steering shaft 22 in the left (or right) direction. 2
Steering a and 21b to the left (or right). In this way, when the pin 45 and the frame body 45a are located behind the rotation center of the rotating body 43, the left and right rear wheels 2
1a and 21b are controlled in opposite phases to the left and right front wheels 14a and 14b, and the steering angle thereof is the same as above.
The distance increases as the distance between the pin 45 and frame pair 45a and the center of rotation of the rotating body 43 increases.

As can be understood from the above operation description, the positions of the pin 45 and the frame 45a are moved according to the rotation of the motor 60, the motor shaft 49, and the threaded rotating shaft 48, and the left and right front wheels 14a,
Since the steering direction and the magnitude of the steering angle of the left and right rear wheels 21a, 21b in response to the steering of the rear wheel 14b are arbitrarily controlled, the rear wheel steering angle characteristic can be changed to a desired characteristic, and the maneuverability of the vehicle is improved. do.

In addition, in this embodiment, the swing lever 44
In order to convert the rocking motion of the rear wheel steering shaft 22 into a reciprocating motion, a guide groove 44c is provided on the rocking lever 44 side and a pin 47 is provided on the rear wheel steering shaft 22 side. Even if the guide groove is provided on the rear wheel steering shaft 22 side and the pin is provided on the swing lever 44 side, the same effect as in the above embodiment can be expected. In addition, in this embodiment, the coupling mechanism 40 is provided parallel to the road surface, and the rotation of the input shaft 41 is converted by the ball nut 46 into the rotation of the rotating body 43 in a plane parallel to the road surface, so that the swing lever 44 is moved parallel to the road surface. However, the coupling mechanism 40 is installed perpendicularly to the road surface, and the rotating body 43 is directly rotated perpendicularly to the road surface by the rotation of the input shaft 41, so that the swing lever 44 is swung perpendicularly to the road surface. It is also possible to displace the rear wheel steering shaft 22 in its axial direction by moving the rear wheel steering shaft 22. As a result, ball nut 4
It is also possible to omit the rotation conversion mechanism like 6.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional plan view of essential parts of a rear wheel steering device according to the present invention, Fig. 2 is a vertical cross-sectional side view taken along the - line in Fig. 1, and Fig. 3 is a rear wheel steering device according to the present invention. FIG. 1 is a plan view schematically showing an example of a vehicle. Explanation of symbols, 10...Front wheel steering mechanism, 11...
Steering handle, 14a, 14b...Front wheel, 15...
...Rack shaft, 20...Rear wheel steering mechanism, 21a, 2
1b... Rear wheel, 22... Rear wheel steering shaft, 30... Rotating shaft, 40... Connection mechanism, 41... Input shaft, 42
... Housing, 43 ... Rotating body, 43b ... Guide groove, 44 ... Rocking lever, 44c ... Guide groove,
45...Pin, 46...Ball nut, 47...
Pin, 48...Threaded shaft.

Claims (1)

[Scope of utility model registration request] A rotating shaft whose front end is connected to a front wheel steering mechanism and rotates in accordance with the front wheel steering of the mechanism, and a rear end of the rotating shaft is connected to a rear wheel steering shaft of the rear wheel steering mechanism to rotate the rotating shaft. A rear wheel steering device for a front and rear wheel steered vehicle comprising a coupling mechanism for steering the rear wheels by displacing the rear wheel steering shaft in its axial direction according to the a housing assembled to the vehicle body; a rocking lever rotatably pivoted within the housing and perpendicular to the rear wheel steering shaft in its neutral position; a connecting means connected to a rear wheel steering shaft to convert the rocking motion of the lever into an axial movement of the rear wheel steering shaft; a rotating body having a radial guide groove and pivotally supported on the housing; a rotary drive means that directly or indirectly drives the rotary body in response to rotation of the rotary shaft; and a rotary drive means that is assembled to the swing lever and slidably fitted into the guide groove to rotate the rotary body. A rear wheel of a front-rear wheel steered vehicle, characterized in that the rear wheel of a front-rear wheel steered vehicle is constituted by a pin that swings the swinging lever in accordance with the movement of the swinging lever, and a pin movable mechanism that is assembled to the swinging lever and moves the pin in the longitudinal direction of the lever. Steering device.