JPH0230384Y2 - - 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 steered vehicle capable of steering the rear wheels of the vehicle in conjunction with the steering operation of the front wheels.

(Prior Art) In general, this type of rear wheel steering device includes a steering link mechanism that is connected to a pair of left and right rear wheels and has an actuation rod that displaces in the left and right direction, and a steering link mechanism that operates the actuation rod of the steering link mechanism to steer the front wheels. The system is equipped with an operating mechanism that steers the rear wheels by displacing them according to The sensor is configured to detect this and transmit it to the actuation mechanism to steer the rear wheels. Further, this type of rear wheel steering device may be configured such that the steering angle ratio between the front and rear wheels changes depending on the driving condition of the vehicle, such as the front wheel steering angle and the vehicle speed.

By the way, in this kind of rear wheel steering device, as proposed in Utility Model Application No. 154269/1983 and shown in FIG. 6, the operating mechanism consists of a guide rail 1 fixed to a part of the vehicle body, and a It is composed of a swinging lever 2 disposed above and a movable fulcrum 3 which is interposed between these two 1 and 2 so as to be movable in the axial direction, supports the swinging lever 2, and serves as the center of its swinging. The movable fulcrum 3 is moved in the left-right direction by a hydraulic actuator, a motor, or the like as a moving means. As a result, the movement of the movable fulcrum 3 in this operating mechanism is controlled in accordance with the vehicle speed, for example, and the lever ratio at the connection point between the front and rear connecting rods 5 and 6 is changed to adjust the steering angle ratio of the front and rear wheels to the vehicle speed. It is changed according to the situation.
However, in such an operating mechanism, since the swinging lever 2 is only supported by the movable fulcrum 3, its left and right ends tend to move up and down around the movable fulcrum 3, and the swinging lever 2 moves back and forth. Since the movable fulcrum 3, which is the center of swing in the direction, moves gradually from side to side, it is difficult to keep the swing lever 2 in a stable state at all times and move the connecting rods 5, 6 back and forth.

(Purpose of the invention) The present invention was devised to solve this problem, and its main purpose is to support the swinging member on the vehicle body, which operatively connects the connecting members connected to the front and rear steering link mechanisms. The system maintains a stable state at all times, allows the rear wheels to be controlled not only by the steering angle of the front wheels but also by the driving conditions of the vehicle, such as vehicle speed, and can arbitrarily select in-phase or reverse phase with respect to the front wheels. The purpose is to improve maneuverability in this way.

(Structure of the invention) In order to achieve the above object, the present invention includes a rear wheel steering link mechanism that includes a rear wheel steering link mechanism that is connected to a pair of left and right rear wheels and is displaceable in the left and right direction, and A swing member is rotatably supported by the vehicle body between the mechanism and the front wheel steering link mechanism, extends in the left-right direction, and has both left and right swing ends swinging in the front-rear direction, and A movable connecting part that is movable in the left-right direction of the moving member, a fixed connecting part located offset to one side from the supporting part of the swinging member, and a fixed connecting part that is connected to the fixed connecting part and connected to the front steering link mechanism. a front connecting member that transmits the steering state of the front wheels to the swinging member; and a front connecting member that is connected to the movable connecting portion and connected to the rear steering link mechanism and transmits the swinging state of the swinging member to the link mechanism. The present invention is characterized in that it is configured to include a rear connecting member and an actuator that moves the movable connecting portion according to the driving condition of the vehicle.

(Operations and Effects of the Invention) Accordingly, in the present invention, by holding the swinging member in a stable state and moving the movable coupling part according to the driving condition of the vehicle such as the vehicle speed, the movable coupling part The position of the swing member can be changed from the fixed connection part side to the opposite side with respect to the swing center of the swing member. Therefore, according to the present invention, the rear wheels can be steered according to the front wheel steering angle, and the steering angle ratio of the front and rear wheels can be controlled according to the vehicle speed. It can also be steered.

(Embodiment) Hereinafter, an embodiment of the present invention will be described based on the drawings. FIG. 1 schematically shows a vehicle equipped with a rear wheel steering device according to the present invention.

In this vehicle, the relay rod 11 that constitutes the steering link mechanism 10 on the front wheel side is displaced in the left-right direction by the operation of the steering wheel 13, and is connected via a tie rod to knuckle arms 12, 12 that provide a steering angle to each front wheel WF. has been done. Furthermore, the relay rod 21 constituting the steering link mechanism 20 on the rear wheel side is displaced in the left-right direction by the action of a push-pull cable 42, which will be described later. are connected via. Both relay rods 11 and 21 of these link mechanisms 10 and 20 are connected to an actuating device 30, a front push-pull cable 41, and a rear push-pull cable 4.
It is connected by 2.

The actuating device 30, as shown in FIGS. 1 to 3,
It is assembled to the vehicle body between a steering link mechanism 10 on the front wheel side and a steering link mechanism 20 on the rear wheel side. This actuating device 30 includes an arm 32 integral with a support shaft 31 rotatably supported on the vehicle body.
and a case 33, both of which are 32, 3
3 constitutes the swinging member of the present invention. The arm 32 extends to the left above the case 33, and is provided with a fixed connecting portion 34a at the front end thereof. The case 33 extends in the left-right direction around the support shaft 31, and a drive gear 35 and a rack bar 36 are housed within the case 33. The drive gear 35 is rotatably supported substantially at the center of the case 33, and is constantly engaged with a rack bar 36 that is slidable on a rail 33a provided at the bottom of the case 33. Further, the drive gear 35 is connected to the belt 3
The rack bar 36 is driven by the motor 37b via the shaft 7a to slide the rack bar 36 in the left-right direction. This rack bar 36 has a movable connecting portion 3 approximately in the center on the rear side.
4b is provided. The movable connecting portion 34b projects rearward from a slit-shaped opening 33b provided in the case 33, and moves laterally and integrally with the rack bar 36. Note that the drive of the motor 37b is controlled by a control circuit 38b that is activated by a vehicle speed signal from a vehicle speed sensor 38a.

The front push-pull cable 41 connects the relay rod 11 and the arm 32, and its front end is connected to the relay rod 11 via a swing arm 43, and its rear end is connected to the fixed connection part 34a. In addition, the rear push-pull cable 42
connects the relay rod 21 and the rack bar 36; its front end is connected to the movable connecting portion 34b, and its rear end is connected to the relay rod 21 via a swing arm 44.

In the rear wheel steering device configured in this way,
By appropriately controlling the drive of the motor 37b of the actuating device 30 according to the vehicle speed, the movable connecting portion 34b is gradually moved to the fixed connecting portion 34a side (left side) and the opposite side (right side) with respect to the support shaft 31. In addition, by steering the front wheel WF in the left and right direction, the front push-pull cable 41 can be pulled.
By pushing, the arm 32 and case 33 can be swung back and forth.

By the way, as shown in FIG.
If the position b coincides with the support shaft 31,
Since the rear push-pull cable 42 is not pulled or pushed, the rear wheel WR is maintained in a neutral state without being steered. Further, when the movable connecting portion 34b moves from the support shaft 31 to the fixed connecting portion 34a side, the rear push-pull cable 42 is pulled and pushed in the same direction as the front push-pull cable 41, and the rear push-pull cable 42 is pulled and pushed in the same direction as the front push-pull cable 41.
Steering the WR in the opposite direction (opposite phase) to the front wheel WF. In this case, the rear wheel steering angle δr with respect to the front wheel steering angle δf
(Front and rear wheel steering angle ratio k=δr/δf) is determined by the distance from the support shaft 31 to the movable connecting portion 34b. Further, when the movable connecting portion 34b moves from the support shaft 31 to the side opposite to the fixed connecting portion 34a, the rear push-pull cable 42 is connected to the front push-pull cable 4.
Contrary to the pulling and pushing of 1, the rear wheel is pushed and pulled.
Steering the WR in the same direction (same phase) as the front wheel WF. The front and rear wheel steering angle ratio k in this case is also determined by the distance from the support shaft 31 to the movable connecting portion 34b.

In this way, in this embodiment, since the arm 32 and the case 33, which are swinging members, are supported on the vehicle body, both of them can be maintained in a stable state and operated reliably, and the front and rear wheels can be The steering angle ratio k can be controlled according to the vehicle speed V, for example, as shown in FIG. In FIG. 4, the front and rear wheel steering angle ratios k are opposite in phase on the + side and in phase on the one side.

(Modified Example) In the above embodiment, the arm 32 and the case 33 are used as the swinging members of the actuating device 30, and the arm 32 is provided with the fixed connection part 34a, and the case 33 is provided with the movable connection part 34b. However, in the present invention, the arm 32 may be omitted and the fixed connecting portion 34a may be provided on the case 33.

Further, in the present invention, an actuating device 50 shown in FIG. 5 can be used in place of the actuating device 30 of the above embodiment. This actuating device 50 includes a case 5 integrated with a support shaft 51 rotatably supported on the vehicle body.
2 as a main body, a screw bolt 53 rotatably supported inside the screw bolt 53, a movable connecting portion 54 that is screwed onto the screw bolt 53 and advances and retreats, and a motor 55 that rotationally drives the screw bolt 53. . Further, a fixed connecting portion (not shown) is provided on the front right side of the case 52. Thereby, the movable connecting portion 54 is moved left and right with respect to the support shaft 51 by the motor 55 and the screw bolt 53, and functions similarly to the actuating device 30 in the first embodiment.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing the main parts of a vehicle equipped with a rear wheel steering device according to the present invention, and FIG. 2 is an enlarged longitudinal sectional front view of an actuating device constituting the rear wheel steering device.
Fig. 3 is an enlarged vertical side view of the same device, Fig. 4 is a graph showing the steering state of the rear wheels, Fig. 5 is a perspective view of a modification of the actuating device as seen diagonally from behind, and Fig. 6 is the actuating device. It is a perspective view showing a conventional example. Explanation of symbols, 10, 20... Steering link mechanism, 21... Relay rod (operating rod),
30... Actuation device, 31... Support shaft, 32... Arm, 33... Case, 34a... Fixed connection part,
34b...Movable connection part, 35...Drive gear,
36...Rack bar, 37b...Motor, 41,
42... Push-pull cable, 50... Actuation device.

Claims (1)

[Scope of utility model registration request] A rear wheel steering link mechanism that is connected to a pair of left and right rear wheels and has an actuation rod that moves in the left and right direction, and a rear wheel steering link mechanism that is rotatably supported on the vehicle body between the link mechanism and the front steering link mechanism and moves in the left and right direction. A swinging member extending to the left and right swinging ends of which swings in the front-rear direction, a movable connecting part provided on the swinging member and movable in the left-right direction of the swinging member, and a support part of the swinging member. a fixed connecting part located offset to one side; a front connecting member connected to the fixed connecting part and connected to the front wheel side steering link mechanism to transmit the steering state of the front wheels to the swinging member; a rear connecting member that is connected to the connecting portion, is connected to the rear wheel side steering link, and transmits the swinging state of the swinging member to the link mechanism; and the movable connecting portion is moved according to the driving state of the vehicle. A rear wheel steering device for a front and rear wheel steered vehicle, comprising an actuator.