JPH0321336Y2 - - 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 that can steer the rear wheels of the vehicle in conjunction with the front wheel steering operation. a rotary shaft whose front end is connected to a steering link mechanism, extends rearward and rotates in response to steering operation of the front wheels; and this rotary shaft is connected to an operating rod of a rear wheel side steering link mechanism and rotates in response to rotation of the rotary shaft. The present invention relates to 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 actuating rod in its axial direction.

[Conventional technology]

In this type of rear wheel steering device, a device in which the steering angle ratio and steering direction of the rear wheels with respect to the front wheels are changed by the coupling mechanism has conventionally been disclosed in Japanese Patent Laid-Open No.
Publication No. 26363, Japanese Unexamined Patent Application Publication No. 1983-26364, Japanese Unexamined Patent Publication No. 1983
This is proposed in Publication No. 26365, etc. by the way,
In the device proposed in the publication, the coupling mechanism includes an input shaft rotated by the rotating shaft, and an output shaft swingably coupled to the input shaft via a universal joint. The drive means includes a drive means for tilting the output shaft with respect to the input shaft, and the steering angle ratio of the rear wheels to the front wheels is changed by changing the inclination angle of the output shaft with respect to the input shaft by the drive means. and the steering direction can be changed.

[Problem that the invention attempts to solve]

By the way, in the conventional device described above, the actuating rod is integrally connected to the output shaft, so that when the output shaft is tilted with respect to the input shaft, even when the input shaft does not rotate, the actuation rod is integrally connected to the output shaft. The actuating rod is moved in its axial direction, changing the alignment of the rear wheels, especially the toe-in, which deteriorates steering stability.

[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 assembled to a housing assembled to the vehicle body and rotated by the rotary shaft. a first shaft to be moved; a second shaft assembled to the first shaft and rotatable about an axis parallel to the axis of the actuating rod in a neutral position; and a second shaft provided integrally with the second shaft. an arm that extends in a direction perpendicular to the rotational axis of the second shaft; and a second arm that is connected to the extending end of this arm via a ball joint and that is neutral to the second arm that is provided on the actuating rod. The second shaft is configured to include a connecting link connected via a ball joint on the axial extension line of the second shaft at a certain position, and a driving means assembled to the first shaft to rotate the second shaft.

(Operation of the invention) In the present invention, when the rotary shaft rotates in accordance with the steering when the front wheels are steered, the first shaft rotates around its axis. If the first shaft is tilted at a predetermined angle to one side with respect to the rotation axis of the first shaft, the rotation of the first shaft to one side caused by the front wheel being steered, for example, to the right (or left). The arm is swung to one side, this movement is transmitted via the connecting link to the actuating rod, which is moved to one side of its axis and the rear wheel is steered to the right (or left), i.e. The steering direction of the rear wheels with respect to the front wheels is assumed to be in the same phase.In addition, when the first shaft rotates, if the extending direction of the arm is not inclined with respect to the rotation axis of the first shaft (if they match) ), even if the front wheels are steered to the right or left and the first shaft is rotated in either direction, the first shaft, second shaft, and arm will only rotate as one. The connecting link is not pushed and the actuating rod does not move in any direction. Therefore, at this time, even if the front wheels are steered, the rear wheels are not steered. Furthermore, when the first shaft is rotated, the arm The direction of extension is the first
If the shaft is tilted at a predetermined angle to the other side with respect to the rotation axis of the shaft, the arm will rotate as the first shaft rotates to one side, which is caused by steering the front wheel to the right (or left), for example. is swung to the other side,
This movement is transmitted via the connecting link to the actuating rod, which is moved in the other direction of its axis to steer the rear wheel to the left (or right). That is, the steering direction of the rear wheels with respect to the front wheels is set to be in opposite phase.

[Effect of idea]

By the way, in the present invention, the extending direction of the arm with respect to the rotational axis of the first shaft described above can be changed by rotating the second shaft about the axis using the driving means. Therefore, if the extending direction of the arm is controlled according to the vehicle speed by the drive means, the steering angle ratio of the rear wheels to the front wheels can be changed appropriately according to the vehicle speed, and the steering direction of the rear wheels with respect to the front wheels can be changed as appropriate. In-phase, immobile, or anti-phase can be selected. Further, in the present invention, by rotating the second shaft around its axis by the drive means in the neutral position, the steering angle ratio and steering direction of the rear wheels with respect to the front wheels can be changed. Since the link only moves in a conical manner with the center of the ball joint on the operating rod side as its apex, and the operating rod does not move in its axial direction, the rear wheel alignment does not change at all and steering stability is not impaired at all.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

FIG. 3 schematically shows a front and rear wheel steered vehicle equipped with a rear wheel steering device according to the present invention. each front wheel.
It is connected via a tie rod 13 to a knuckle arm 12 that gives a steering angle to the WF. Further, the actuating rod (relay rod) 21 constituting the rear wheel side steering link mechanism 20 is displaced in the left-right direction (axis L1 direction) by a coupling mechanism A to be described later, and is a knuckle arm that provides a steering angle to each rear wheel WR. 2
2 through a tie rod 23. The rack bar 11 and the actuating rod 21 are connected to a rotating shaft 30 via a connecting mechanism A.

The rotating shaft 30 is divided into five shafts: a main shaft 31, a pair of front and rear intermediate shafts 32, 33, and a pair of front and rear pinion shafts 34, 35. It is connected to a rack bar 11. This main shaft 31 is rotatably supported by the vehicle body and extends a predetermined length from the front of the vehicle body toward the rear.

As shown in FIGS. 1 to 3, the connection mechanism A includes a housing 40 assembled to the vehicle body, a first shaft 41, a second shaft 42, an arm 43, a connection link 44, and It is constituted by an electric motor 49 as a driving means. As shown in FIG. 1, the first shaft 41 consists of a shaft portion 41a and a pair of support portions 41b, 41b, and is rotated around the axis L2 by the shaft portion 41a to the housing 40 via bearings 50, 51. It is movably assembled. In addition, the shaft portion 4 of the first shaft 41
1a has an arc-shaped tooth 41c centered on the axis L2.
is integrally provided, and a rack 35c provided on a ball nut 35b assembled to a pinion 35a of a pinion shaft 35 in the rotating shaft 30 meshes with the rod 41c.

The second shaft 42 consists of a large-diameter shaft portion 42a having a gear 42a1 on the outer periphery and a pair of small-diameter shaft portions 42b, 42b provided at both ends of the large-diameter shaft portion 42a. Support part 41 of the first shaft 41 in the state shown in FIG. 2 (neutral position)
The actuating rod 21 is rotatably attached to the actuating rod 21 via a pair of bearings 52, 53 and movable holders 54, 55 about an axis L3 parallel to the axis L1 of the actuating rod 21. The arm 43 is provided integrally with the second shaft 42 and extends in a direction perpendicular to the axis L3 of the second shaft 42. Connecting link 4
4 is a ball joint 4 at the extending end of the arm 43.
5 and is connected to an arm 21a integrally provided on the actuating rod 21 via a ball joint 46 on an extension of the axis L3 of the second shaft 42 in the neutral position. The electric motor 49 is assembled to the support portion 41b of the first shaft 41, and a gear 49 is attached to the rotating shaft 49a.
a1 is provided, and the gear 49a1 is a gear 42a provided on the large diameter shaft portion 42a of the second shaft 42.
It meshes with 1. Further, the electric motor 49 is configured so that its forward rotation, stop, and reverse rotation are controlled according to the vehicle speed.

In this embodiment configured in this manner, when the steering wheel WS is operated, the rack bar 11 is displaced in the left-right direction and the front wheel WF is steered. During this steering, the rotary shaft 30 is rotated by the rack bar 11, and the first shaft 41 in the coupling mechanism A is rotated around its axis L2 (clockwise/counterclockwise in FIG. 2).

Therefore, when the first shaft 41 rotates, if the extending direction of the arm 43 is inclined 90 degrees toward the front of the vehicle as shown by the solid line in the figure with respect to the rotation axis L2 of the first shaft 41, the front wheel As the first shaft 41 rotates counterclockwise (or clockwise) as shown in FIG. This is transmitted to the actuating rod 21 via the connecting link 44, and the actuating rod 21 is moved to the left (or right) in the direction of its axis L1, causing the rear wheel WR to swing to the right (or left). ). That is, the steering directions of the rear wheels WR and the front wheels WF are made to be in phase. This operation can be performed by changing the steering angle of the rear wheel WR with respect to the front wheel WF if the extending direction of the arm 43 is inclined toward the front of the vehicle with respect to the rotation axis L2 of the first shaft 41 when the first shaft 41 rotates. Although there is a difference in the ratio, the same result can be obtained (rear wheel WR
The steering angle ratio to the front wheel WF is maximum when indicated by the solid line in the figure).

Further, the second shaft 42 is rotated by 90 degrees from the position indicated by the solid line in the figure by the electric motor 49, and when the first shaft 41 is rotated, the direction in which the arm 43 extends is as indicated by the imaginary line in FIG. As shown, if it is not inclined with respect to the rotational axis L2 of the first shaft 41 (if it is aligned), the front wheel WF is steered to either the right or left direction and the first shaft 41 is rotated. No matter which direction it is rotated, the first shaft 41, second shaft 42, and arm 43 only rotate together, the connecting link 44 is not pushed, and the actuating rod 21 is rotated in either direction. Don't move. Therefore, at this time, even if the front wheels WF are steered, the rear wheels WR are not steered.

Further, the second shaft 42 is rotated by an electric motor 49 by 90 degrees or more from the position indicated by the solid line in the figure, and when the first shaft 41 is rotated, the arm 4
3 is the rotation axis L2 of the first shaft 41
If the vehicle is tilted toward the rear of the vehicle, the front wheels
As the first shaft 41 rotates as the WF is steered to the right (or left), the arm 43 swings to the right (or left), and this This is transmitted to the actuating rod 21, and the actuating rod 21 is moved to the right (or left) in the direction of its axis L1, and the rear wheel WR is steered to the left (or right). In other words, the front wheel of the rear wheel WR
The steering direction with respect to WF is assumed to be in opposite phase. In this operation, when the first shaft 41 rotates, the extending direction of the arm 43 is aligned with the rotation axis L of the first shaft 41.
If the vehicle is tilted to the rear relative to 2, the rear wheel WR
Although there is a difference in the steering angle ratio to the front wheel WF,
Similarly obtained (the steering angle ratio of the rear wheel WR to the front wheel WF is such that the extending direction of the arm 43 is the first shaft 4
(This is maximum when the vehicle is tilted 90 degrees toward the rear of the vehicle with respect to the rotation axis L2 of 1).

By the way, in this embodiment, the second shaft 42 is rotated around the axis L3 by the electric motor 49 that is controlled according to the vehicle speed.
is rotated with respect to the first shaft 41, thereby changing the extending direction of the arm 43 with respect to the rotation axis L2 of the first shaft 41, which changes the steering angle ratio and steering of the rear wheel WR with respect to the front wheel WF. The direction changes appropriately depending on the vehicle speed. In addition, in this embodiment, the electric motor 49 drives the second
By rotating the shaft 42 around its axis L3, the steering angle ratio and steering direction of the rear wheels WR to the front wheels WF are changed, and at this time, the connecting link 44 moves in a conical manner with the center of the ball joint 46 as the apex. The operating rod 21 moves along its axis L.
Since it does not move in one direction, the rear wheel WR alignment does not change at all and steering stability is not compromised at all.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional rear view of the main parts of the rear wheel steering device according to the present invention, Fig. 2 is a cross-sectional plan view thereof, and Fig. 3 schematically shows an example of a vehicle equipped with the rear wheel steering device according to the present invention. FIG. Explanation of symbols, 10... Front wheel side steering link mechanism, 20... Rear wheel side steering link mechanism, 21... Actuation rod, 21a... Arm provided on actuation rod, 30... Rotating shaft, WF...
...Front wheel, WR...Rear wheel, L1...Axis of operating rod, A...Connection mechanism, 40...Housing, 41
...First shaft, 42...Second shaft, 43
...Arm, 44...Connection link, 45, 46...
...Ball joint, 49...Electric motor (drive means), L2...Rotation axis of first shaft, L3
...The rotation axis of the second shaft.

Claims (1)

[Scope of utility model registration request] a rotary shaft whose front end is connected to the front wheel steering link mechanism, extends rearward and rotates in accordance with the steering operation of the front wheels; and this rotary shaft is connected to an operating rod of the rear wheel steering link mechanism to rotate the rotary shaft. In the rear wheel steering device for a front and rear wheel steered vehicle, the coupling mechanism is provided with a coupling mechanism that steers the rear wheels by displacing the actuating rod in its axial direction in accordance with the rotation of the coupling mechanism. a first shaft mounted on the first shaft and rotatable by the rotary shaft; a first shaft mounted on the first shaft and rotatable in a neutral position about an axis parallel to the axis of the actuating rod; 2
a shaft, an arm that is integrally provided on the second shaft and extends in a direction perpendicular to the rotational axis of the second shaft, and is connected to the extending end of the arm via a ball joint. a connecting link that is connected to a second arm provided on the actuating rod via a ball joint on an axial extension line of the second shaft in a neutral position; 1. A rear wheel steering device for a front and rear wheel steered vehicle, comprising a drive means for rotating a shaft.