JP2829009B2 - Rear wheel steering system for motorcycles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a rear wheel steering system in which a rear wheel is steered in accordance with a steering operation of a front wheel of a motorcycle or a turning operation such as a weight shift of a driver. Regarding the device, especially by devising the connection structure of the rear wheel support member with the vehicle body, the lateral force acting on the rear wheels can be controlled without providing a special steering mechanism for forcibly turning the rear wheels according to the steering of the front wheels. The present invention relates to a rear wheel steering device in which a rear wheel is naturally steered by force.

[Conventional technology]

Conventionally, in motorcycles, it was common to steer only the front wheels, but recently, by steering the rear wheels together with the front wheels, for example, to improve running stability in a middle or high speed range,
Alternatively, it has been considered to reduce the radius of rotation in the low speed range.

As such a front and rear wheel steering device of a motorcycle, for example, a front fork with a steering wheel and a rear wheel supported to be able to turn left and right are connected via a transmission link with a cam mechanism interposed. There is (for example,
178275).

[Problems to be solved by the invention]

The above-described conventional device has a structure in which the rear wheel is forcibly steered in conjunction with the operation of the steering wheel, and therefore requires a transmission link, a cam mechanism, and the like, and has a disadvantage that the structure is complicated.

The present invention has been made in view of the above-described conventional situation, and has a simple configuration that merely devises a connection structure of a rear wheel support member and a vehicle body, and naturally steers the rear wheel by a lateral force acting on the rear wheel. It is an object of the present invention to provide a rear wheel steering device for a motorcycle.

[Means for solving the problem]

According to the present invention, a rear wheel is pivotally supported at a rear end portion of a rear wheel support member, and a front end portion of the rear wheel support member is moved relative to a body frame by a pair of left and right link members arranged with the vehicle axis interposed therebetween. A link extension line connecting the left and right link members to the vehicle body side and the rear wheel support member side pivots is swingably connected up and down and intersects substantially on the vehicle axis when viewed from a plane. The link member is a rear wheel steering device of a motorcycle, wherein the link member is capable of swinging up and down and swinging in a plane including the four shaft fulcrums.

Here, when the link extension lines connecting the front and rear shaft fulcrums of the left and right link members of the present invention intersect on the vehicle axis, the two link members are arranged non-parallel to each other, and the line connecting the four shaft fulcrums is trapezoidal. Means that In this case, the intersection of the two link extension lines is behind and in front of the point of application of the lateral force to the rear wheel (the point of contact with the rear wheel and within a range of several centimeters before and after the axle). Both cases are included. The position of the intersection is set according to the steering characteristic to be obtained, as described later.

Further, the point that the two link members can be swung in a plane including the four pivot points can be realized by interposing a rubber bush, a spherical joint, and the like at the pivot points.

[Action]

In the rear wheel steering device according to the present invention, since the left and right link members are arranged non-parallel, a lateral force (so-called cornering force, canvas last) acting on the rear wheel during turning.
As a result, a moment acts on the rear wheel to steer it. In the present invention, since the link member is configured to be swingable in a plane including four pivot points, the rear wheel support member swings by the moment, whereby the rear wheel is naturally steered. Become.

If the intersection of the two link extension lines is set behind the point of application of the lateral force to the rear wheel, the rear wheel is steered in the same direction (in phase) as the front wheel, so that the running stability in the middle and high speed regions Is improved.

On the other hand, when the intersection is set ahead of the action point,
The rear wheels are steered in the opposite direction (opposite phase) to the front wheels, which is advantageous when the turning radius is reduced and the vehicle turns slightly at low speed.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 to 5 are views for explaining a rear wheel steering device of a motorcycle according to one embodiment of the present invention.

In the figure, reference numeral 1 denotes a scooter type motorcycle employing the apparatus of this embodiment, which is shown with a body cover and the like removed. In the body frame 2 of the motorcycle 1, a pair of left and right side pipes 4b is connected to a rear end of a main pipe 4a connected to the head pipe 3 and extending downward, and the side pipe 4b extends rearward from above. It has a configuration. By the above head pipe 3, the front wheel 5
The steering shaft 6a of the front fork 6 that supports the
A steering handle 7 is fixed to the rear end of the steering shaft 6a.

Near the rising portion of the left and right side pipes 4b,
The engine unit 8 is connected by a pair of left and right link members 15 and 16. The engine unit 8 mainly includes an engine body 9 in which a cylinder and a cylinder head are stacked on a crankcase, and a transmission case 10 integrally formed with the crankcase. A wheel 11 is pivotally supported, and a shock absorber 12 is provided between this rear end and the rear of the left side pipe 4b.
Are arranged. That is, the engine unit 8 is a rear shaft supporting member that supports the rear wheel 11. In addition, 13 is an air cleaner and 14 is a carburetor.

The pair of left and right link members 15 and 16 have bushings 17 and 17 formed at the front end of the rod-shaped member and brackets 18 and 18 at the rear end, respectively. It is narrower than the interval between 17 and has a trapezoidal shape as a whole. The bush 17 is formed by inserting a rubber body 17c between the outer cylinder 17a and the inner cylinder 17b fixed to the rod-shaped member, and fixing the rubber body 17b by baking. Further, a slit 17d is formed in the rubber body 17c in the axial direction, so that the rigidity at the center is high and the rigidity at both ends is low. Thereby, the rubber body 17c is relatively easy to bend in the direction perpendicular to the axis, and hardly deforms in the front-rear direction. The bush 17 is supported by a support pin 4c fixed to the side pipe 4b by a support pin 19. The bracket 18 has a U-shape in plan view,
This is the bush formed on the front wall of the crankcase
It is supported by support pins 19 through 20. The bush 20 has the same structure as the bush 17 described above. As a result, the two link members 15 and 16 are connected to the engine unit 8.
Is swingably supported vertically with respect to the vehicle body, and is swingable in a plane including the four bushes 17, 17, 20, 20.

Further, when viewed from a plane, the link extension lines L connecting the pivot points of the bushes 17 and 20 are, as shown in FIG.
It crosses on the vehicle axis l projected on the road surface G and behind the axle 10a that supports the rear wheel 11, and when viewed from the rear or front of the vehicle as shown in FIG. The lines L intersect below the road surface G.

 Next, the operation and effect of this embodiment will be described.

When the motorcycle 1 of this embodiment is running and the front wheel 5 is turned leftward as shown in FIG. 5, the rear wheel 11 has a ground contact point (a point substantially directly below the axle 10a). Lateral force F toward the center of rotation at a magnitude corresponding to the centrifugal force at
Works. When viewed from a plane, as shown in FIG. 3A, the intersection O of the link extension lines L of the left and right link members 15, 16 is located rearward due to the point of action of the lateral force F. A counterclockwise moment about the intersection point O acts on 11 and the engine unit 8 supporting the same, whereby both link members 15 and 16 are pivoted around the bush 20 which is the engine-side shaft fulcrum. Side wheel 11 so that the rear wheel 11 rotates slightly like the front wheel 5.

When the lateral force is applied from the rear, the intersection O is located below the ground contact point (the point of application of the lateral force F) as shown in FIG. Then, a counterclockwise moment about the intersection point O acts on the bush 20 side of the link members 15 and 16, whereby the rear wheel 11 tilts inwardly.

As described above, in this embodiment, the link members 15 and 16 are arranged such that the intersection point O of these extended lines L is located behind the axle 10a when viewed from above and below the road surface G when viewed from behind. When viewed from a plane, the front wheel 5 rotates in the same phase as the front wheel 5, and when viewed from the rear, it is inclined toward the inside of the turn, so that the running stability during middle and high speed running can be improved.

Here, in the above-described embodiment, the rubber bushes are provided at the front and rear ends of both link members. However, this is not necessarily the rubber bush, and it is possible to swing in a plane including four pivot points. Any structure can be used as long as it can support it. For example, as shown in FIG. 6, one having a spherical bearing 21 on one or both of the engine side and the vehicle body side may be employed.

Further, in the above embodiment, the case where the intersection O of the link extension lines L is set behind the axle 10a and below the ground point has been described. However, in the present invention, this intersection O is set ahead of the axle 10a, It can also be set above the ground point.

FIG. 7 shows an example in which the interval between the bushes 20 is further narrowed and the intersection O is set forward of the axle 10a in the above embodiment, and FIG. This is an example in which the intersection O is set ahead of the bush 17.
In any case, a clockwise moment about the intersection O is generated by the lateral force F, and the bush 20 moves to the turning outside in FIG. 7 and the bush 20 moves to the turning inside in FIG. As a result, the rear wheels 11 are steered in the opposite phase to the front wheels 5.

FIG. 9 shows an example in which the intersection point O of the link extension lines L as viewed from the back is set above the road surface G. In this case, the lateral force F causes the rear wheel 11 to incline outward.

In the examples shown in FIGS. 7 to 9, the rear wheel is steered in the opposite phase to the front wheel, so that the radius of rotation is reduced.

In the above-described embodiment, the motorcycle having the unit swivel engine in which the engine unit is also used as the rear wheel supporting member has been described.However, the present invention relates to a case where the rear wheel is supported by a normal rear arm. Of course, it can be applied.

〔The invention's effect〕

As described above, according to the motorcycle rear wheel steering device of the present invention, the rear wheel support member is connected to the vehicle body by the pair of left and right link members, and the extension lines of the two link members are substantially on the vehicle axis. So that the two link members can swing up and down and swing in a plane including the four pivot points, so that the rear wheels can be steered by the lateral force generated during turning. There is an effect that rear wheel steering can be realized without providing a complicated mechanism.

[Brief description of the drawings]

1 to 5 are views for explaining a rear wheel steering device of a motorcycle according to one embodiment of the present invention, wherein FIG. 1 is a plan view, FIG. 2 is a rear view, and FIG. ) Is a cross-sectional plan view of a link member portion, FIG. 3B is a side view of a bush, FIG. 4 is a side view of a motorcycle to which the embodiment device is applied,
5 (a) and 5 (b) are a plan view and a rear view schematically showing an operation, and FIG. 6 is a sectional plan view showing a modification of the link member, and FIGS. 7 to 9 FIG. 9 is a plan view, a plan view, and a rear view schematically showing another embodiment of the present invention. In the figure, 1 is a motorcycle, 4b is a side pipe (body frame), 8 is an engine unit (rear wheel support member),
11 is a rear wheel, 15 and 16 are a pair of left and right link members, 17 and 20 are bushes (shaft fulcrums), l is a vehicle axis, L is a link extension,
O is the intersection.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B62K 21/00 B62K 25/20

Claims (1)

(57) [Claims] A rear wheel is pivotally supported at a rear end of a rear wheel support member, and a front end of the rear wheel support member is moved relative to a vehicle body frame by a pair of left and right link members disposed across the vehicle axis. The left and right link members on the vehicle side,
A link extension line connecting the fulcrum on the rear wheel support member side intersects substantially on the vehicle axis when viewed from a plane, and the two link members are vertically swingable and swing in a plane including the four axle support points. A rear wheel steering device for a motorcycle, wherein the rear wheel steering device is movable.