JPH0351260Y2 - - 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 that can steer the rear wheels of the vehicle in conjunction with the steering operation of the front wheels.

[Prior art]

In front and rear wheel steering vehicles, the rear wheels are steered in the same phase as the front wheels when the vehicle is running at high speeds, and in the opposite phase when running at low speeds. It is desirable to improve maneuverability.

As a mechanical solution to this request, as shown in Japanese Patent Application Laid-Open No. 167563/1986, a link mechanism is proposed in which the front end is connected to the front wheel side steering link mechanism and extends rearward for steering operation of the front wheels. a shaft that rotates accordingly, and a coupling mechanism that connects the shaft to an operating rod of a rear wheel side steering link mechanism and moves the operating rod left and right in accordance with the rotation of the shaft to steer the rear wheels. There are front and rear wheel steering vehicles.

In such a front and rear wheel steered vehicle, the coupling mechanism includes a disc-shaped transmission member provided at the rear end of the shaft, and a crank rod that connects the outer peripheral edge of the transmission member and the intermediate portion of the actuation rod. The transmission member rotates forward and backward in response to the steering operation of the front wheels, and moves the actuating rod in the left-right direction via the crank rod. As a result, the rear wheels are steered in accordance with the steering operation of the front wheels, and especially when the rotation angle of the transmission member is small even if the steering angle of the front wheels is small, the rear wheels are steered in the same phase as the front wheels, and the front wheels are steered in the same phase as the front wheels. When the steering angle is large and the rotation angle of the transmission member is large, the rear wheels are steered in a phase opposite to the front wheels.

[Problem that the invention attempts to solve]

By the way, FIG. 4 schematically shows the operation of such a coupling mechanism, in which reference numeral A indicates the rotation center of the transmission member, reference numeral B indicates the connection point on the transmission member side of the crank rod, and reference numeral C indicates the connection point on the transmission member side of the crank rod. The connection points on the actuating rod side are shown. When the front wheel turns to the right, the transmission member rotates in the direction of arrow a1, rotates connection point B toward b1, and rotates connection point C toward c.
1 side and when turning the front wheel to the left, use arrow a
By rotating in two directions, the connection point B is rotated toward the b2 side, and the connection point C is moved toward the c2 side. As is clear from the same figure during this operation, even though the horizontal rotation angle of the transmission member is the same, the vertical component of the circular motion is the horizontal movement distance of the connection point C (C and c1 and between C and c2), and the movement distances are different from each other. Therefore, in such a coupling mechanism, even if the steering angle of the front wheels in the left-right direction is the same, a problem arises in that the steering angle of the rear wheels differs depending on the steering direction of the front wheels.

[Means for solving problems]

In order to solve this problem, the present invention includes a support member that is provided at the rear end of the shaft and projects rearward at an angle with respect to the axis of the shaft, and an intermediate portion that is connected to the support member. and a connecting rod that is movably supported and bent from the support portion and extends in the left-right direction, and the actuating rod is divided into left and right parts, and the inner end of these two divided rods is rotated to the outer end of the connecting rod. Connected freely.

[Functions and effects of the idea]

As a result, in the present invention, the component of the rotational movement of the support member in the direction perpendicular to the axis of the actuating rod is absorbed between the support member and the connecting rod, and only the left-right direction component is transmitted to the actuating rod. can be moved left and right. Therefore, even if the rotation direction of the support member is different, if the rotation angle is the same, the amount of movement of the actuating rod in the left-right direction will be the same. Therefore, according to the coupling mechanism according to the present invention, if the steering angles of the front wheels in the left-right direction are the same, the steering angles of the rear wheels in the left-right direction are the same.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a front and rear wheel steered vehicle equipped with a rear wheel steering device according to an embodiment of the present invention.

In this vehicle, a rack bar 11 constituting a front wheel steering link mechanism 10 slidably passes through a gearbox 12 and is connected to the inner ends of left and right tie rods 13. Each tie rod 13
The outer ends of the front wheels WF are connected to a knuckle arm 14 that gives a steering angle to each front wheel WF, and by operating a handle 16 integrated with a steering shaft 15 that constantly meshes with the rack bar 11 in the gear box 12, the rack bar 11 moves left and right. Steering the front wheel WF. Furthermore, the rack bar 11 is constantly engaged with a rotary shaft 20a within the gear box 12, and an actuating rod 31 forming a rear wheel steering link mechanism 30 is connected to the rotary shaft 20a and a coupling mechanism 20b.

In the rear wheel side steering link mechanism 30,
The actuating rod 31 extends in the left and right direction of the vehicle,
Both ends thereof are connected via tie rods 33 to a knuckle arm 32 that provides a steering angle to each rear wheel WR. This actuating rod 31 is connected to a connecting mechanism 20 which will be described later.
It moves left and right by the operation of b, and each rear wheel WR is steered.

Therefore, the connecting mechanism 20b is shown in FIGS. 2 and 3.
As shown in the figure, it consists of a support member 21 and a connecting rod 22, which are housed in a casing 23 assembled on the underside of the vehicle body. Further, the actuating rod 31 is composed of a pair of left and right split rods 31a and 31b.

The support member 21 is integrally provided at the rear end of the rotary shaft 20a facing into the casing 23 and rotatably supported by the casing 23, and has a rod shape and is inclined with respect to the axis of the rotary shaft 20a. and protrudes backwards. rotating shaft 2
The intersection of the axis of 0a and the axis of support member 21 is located approximately on the axis of both split rods 31a, 31b. Therefore, the support member 21 supports the rotating shaft 20
The rotation of the shaft 20a causes it to rotate in a conical shape around the axis of the shaft 20a, and the tip of the shaft 20a is connected to the actuating rod 3.
The two split rods 31a and 31b that make up the rod move in a circular motion on an upright plane parallel to the axis. The connecting rod 22 is bent at its center, and the universal joint 2 is attached to the tip of the support member 21 at the center.
It is rotatably supported via 4a. Each split rod 31a, 3 constituting one actuating rod 31
1b is fitted into the casing 23 from the left and right directions, and is supported by the casing 23 so as to be slidable in the left and right directions. The inner end of each split rod 31a, 31b and each outer end of the connecting rod 22 are connected to each universal joint 24.
b, 24c, and are rotatably connected.

In the rear wheel steering device configured in this way,
When the front and rear wheels WF and WR are in a neutral state, the coupling mechanism 20b is in the state shown in FIG. That is,
The support member 21 is located above the axis of the rotating shaft 20a, and both outer ends (universal joints 24b, 24c) of the connecting rod 22 extend in the left-right direction with respect to the above-mentioned line.

When the handlebar 16 is operated in this state, the rack bar 11 slides in the left-right direction to steer the front wheel WF via both knuckle arms 14, and at the same time, the rotary shaft 20a rotates. This results in
The support member 21 rotates in the arrow a1 direction or the arrow a2 direction about the axis of the rotating shaft 20a, and the left-right direction component of the rotational movement of the support member 21 is caused by the rotation of the connecting rod 2.
2 to both split rods 31a, 31b. For this reason, the rear wheel WR has two split rods with 31
It is steered according to the amount of movement of a and 31b in the left and right direction.

Thus, the support member 21 moves from the neutral position to the point indicated by the arrow a.
When rotating in one direction, both split rods 31a, 3
1b gradually moves to the right when the rotation of the support member 21 is within the range of 90°, and when the rotation is within the range of 90° to 180°, gradually moves to the left to return to the neutral state, and then When it falls within the range of 180° to 270°, it gradually moves to the left. Further, when the support member 21 rotates from the neutral position in the direction of arrow a2, only the direction of movement of the split rods 31a and 31b is opposite to that when rotating in the direction of arrow aa1 described above.

Therefore, regardless of the steering direction of the front wheels WF, if the steering angle is small, the rear wheels WR will be gradually steered to the same phase side with respect to the front wheels WF, and if the steering angle of the front wheels WF becomes large, the rear wheels WR will be in a neutral state. The front wheels are gradually steered to the opposite phase side with respect to the front wheels WF.

By the way, in this embodiment, the support member 21
The vertical component during the rotational movement of the support member 21 is absorbed between the rod and the connecting rod 22, and only the horizontal component is transmitted to both the split rods 31a and 31b, so that the split rods 31a and 31b are moved in the left and right direction. Ru. Therefore, even if the rotation direction of the support member 21 is different, if the rotation angle is the same, the amount of movement of both split rods 31a, 31b in the left-right direction is the same, and therefore, the amount of movement of the front wheel WF in the left-right direction is the same. If the steering angles are the same, the steering angles of the rear wheels WR in the left and right directions will be the same.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a front and rear wheel steered vehicle equipped with a rear wheel steering device according to an example of the present invention, Fig. 2 is an enlarged cross-sectional plan view of a coupling mechanism constituting the device, and Fig. 3 is an enlarged longitudinal section of the same. The side view and FIG. 4 are explanatory views of the operation of the conventional coupling mechanism. Explanation of symbols, 10... Front wheel side steering link mechanism, 20a... Rotating shaft, 20b... Connection mechanism, 21... Support member, 22... Connection rod, 23... Casing, 30... Rear wheel side steering link mechanism.

Claims (1)

[Scope of utility model registration request] a shaft whose front end is connected to the front wheel steering link mechanism, extends rearward and rotates in response to the steering operation of the front wheels; and the shaft is connected to an operating rod of the rear wheel steering link mechanism, and the shaft rotates in response to the rotation of the shaft. In a front and rear wheel steered vehicle comprising a coupling mechanism for moving an actuating rod in the left and right direction to steer the rear wheels, the coupling mechanism is provided at a rear end of the shaft and tilted with respect to the axis of the shaft. The actuating rod is comprised of a support member that protrudes rearward, and a connecting rod that is rotatably supported at its intermediate portion by the support member and extends left and right by bending from the support member, and the actuating rod is divided into left and right parts. A rear wheel steering device for a front and rear wheel steered vehicle, characterized in that the inner ends of these two split rods are rotatably connected to the outer ends of the connecting rod.