JPH01204885A - Rear-wheel steering gear for two wheeler - Google Patents

Abstract

PURPOSE:To control the transmission of vibration in a rear wheel to a handle lever by attaching a steering arm, cantileveringly supporting the rear wheel, pivotally to a swing arm tip, and installing a second steering shaft in the point midway in a steering system ranging from a first steering shaft to the steering arm. CONSTITUTION:A first steering shaft 2 as one body with a handle bar 4 is supported on a head pipe 22 fixed to a front end upper part 1a of a frame 1, and a second steering shaft 5, fixed to a rear end upper part 1b of the frame, is supported on an end pie 23. Each base end of isometric offset levers 7, 8 is tightly attached to a lower end of the first steering shaft 2 and both vertical ends of the second steering shaft 5, and an interval between both tip parts of these levers 7, 8 is connected by a first tie rod 9. A rear wheel 11 is cantileveringly supported on a rear steering arm 16 pivotally attached to a vertical pair of swing arms 12, 13 at a forked vertical part 1c of the frame 1, and an interval between an intermediate part of this rear steering arm 16 and a tip part of the offset lever 10 is connected by a second tie rod 26.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a rear wheel steering device for two-wheeled vehicles such as motorcycles and bicycles, which steers the rear wheels in conjunction with the steering operation of a handlebar for front wheel steering. It is related to.

(Prior Art) In recent years, so-called four-wheel steering devices of a type that simultaneously steer two front wheels and two rear wheels have already been put into practical use in automobiles.

On the other hand, in two-wheeled vehicles such as motorcycles, by simultaneously steering the front and rear wheels, it is possible to reduce the movement of the rider (driver) required for steering (shifting the weight in the direction of steering), and to reduce the minimum turning radius. Based on the knowledge that it is possible to reduce the size of the steering wheel, a device that steers both the front wheels and the rear wheels in conjunction with the steering of the front wheels has recently been developed.

By the way, as a prior art of such a rear wheel steering device, for example, as seen in Japanese Patent Laid-Open No. 61-160374, the axle of the rear wheel is pivotably supported on a drive shaft perpendicular to the center line of the vehicle body, and the steering wheel is An offset lever is fixed to the lower end of the steering shaft that has a bar at the upper end, and one end of the push-pull cable is attached to the offset lever, and the other end of the push-pull cable is attached to a rocker arm that is pivoted horizontally to the rear frame. Then, the rocker arm is connected to the rear steering arm disposed on the axle of the rear wheel via a bearing, and the rocker arm is rotated in conjunction with the turning operation of the handlebar, thereby steering the rear wheel. There is a device with a similar structure.

(Problems to be Solved by the Invention) In the case of the above-mentioned known steering device, the rear wheels are steered via a rocker arm that rotates horizontally, so the shape of the link members that make up the steering system is complicated. Furthermore, it is not easy to attach the link member to the vehicle body. Moreover, since the fulcrum (rotation center) position of the tie rod connected to the rear steering arm is supported by the rocker arm, the rear wheel can be turned symmetrically to the left and right in response to left and right rotation of the handlebar. placement is difficult.

This invention has been made in view of the above points, so that the steering system from the handlebar to the steering arm of the rear wheel is composed of a combination of members with simple shapes, and is easy to manufacture.
It is highly durable, and can be easily arranged to allow the rear wheel to turn symmetrically left and right in response to left and right rotation of the handlebar. Vibrations from the rear wheels are less likely to affect the handlebars directly.
The present invention aims to provide a rear wheel steering device for a two-wheeled vehicle.

(Means for Solving the Problems) The gist of the present invention for achieving the above-mentioned object is that the rear wheel is rotatably attached to the tips of a pair of upper and lower rear swing arms extending rearward from the rear of the frame. A rear steering arm supported cantilevered on the frame is pivotably mounted, and a first steering shaft having a handlebar at an upper end is mounted on the front end of the frame, and a second steering shaft is mounted on the rear of the frame, each of which is pivotable in a substantially vertical direction. A first tie rod that is freely supported and connects the first steering shaft and the second steering shaft by a first tie rod that is offset from both shafts, and the second steering shaft is offset from the shaft. It is connected to the rear steering arm using a tie rod.

(Function) According to the rear wheel steering device of the present invention, as one of the constituent members of the steering system extending from the handlebar to the rear steering arm of the rear wheel, the rear wheel steering device rotates approximately vertically at the rear of the frame near the pivot point of the rear swing arm. A movably supported second steering shaft is interposed, which allows each link that makes up the steering system to have a simple shape, and the operation of each link during steering is in the longitudinal direction of the vehicle body or in the direction around the vertical axis. By positioning the first steering shaft and the second steering shaft on the center line of the vehicle body, the rear wheels can be rotated symmetrically to the left and right in response to left and right rotation of the handlebar. It becomes easier to arrange links. In addition, most of the reaction force from the road surface and the vibration of the rear wheels during driving are absorbed by the second steering shaft supported by the frame, and are less likely to act directly on the first steering shaft. Furthermore, the steering system from the handlebar to the steering arm is fixed to the frame at two points, the first steering shaft and the second steering shaft, which are part of the steering system, so it has high structural strength and can be easily moved from the handlebar to the steering arm. steering force is transmitted to the rear steering arm.

(Example) Fig. 1 is a partially omitted left side view of a motorcycle showing an embodiment of the present invention, Fig. 2 is a view taken along the line ■-■ in Fig. 1, and Fig. 3 is a front view of the same. FIG. 4 is a front view of the same.

As shown in FIG. 1, the frame 1 of the motorcycle is inclined slightly downward toward the rear from the upper part 1a of the front end on the vehicle body center plane N (FIGS. 2 and 3), and then extends approximately to the rear end. It extends horizontally and, as shown in FIG. 5, is formed into a bifurcated vertical portion 1c that is divided into both sides at the upper rear end 1b,
Further, each vertical portion 1c is bent at a right angle at its lower end to form a horizontal portion 1d extending forward.

The first steering shaft 2 shown in FIG. 1 is welded to the upper front end 1a of the frame 1 on the vehicle center plane N, and is welded to the head pipe 22, which is slightly tilted rearward with respect to the vertical direction.
It penetrates through the bearing 3 and is rotatably disposed on the bearing 3. A handlebar 4 extending from both sides is integrally fixed to the upper end of the first steering sleeve 2.

Further, a second steering shaft 5 is rotatably disposed on a bearing 6, passing through an end pipe 23 vertically welded to the rear end upper part 1b of the frame on the center plane N of the vehicle body.

Further, at the lower end of the first steering shaft 2 and the upper end of the second steering shaft 5, the base ends of offset levers 7.8 are arranged such that the distal ends of the offset levers 7.8 move from the vehicle body center plane N to the same side (here, to the left). It is stuck out and fixed. The lower surface of the tip of the offset lever 7 and the upper surface of the tip of the offset lever 8 are connected to a rod, which is a type of universal joint, so that the offset ma is equal to the first steering sleeve 2 and the second steering shaft 5, respectively. They are connected by a first tie rod 9 with ends 9a and 9b attached to both ends.

The rear wheel 11 is cantilevered by a rear steering arm 16 that is pivotally connected to a pair of upper and lower trading type rear swing arms 12 and 13 that extend rearward from between the bifurcated vertical portions lc of the frame 1. That is, as shown in FIGS. 1 and 2, a pair of upper and lower rear swing arms 12, 1
The proximal end portions of 3 are pivotally mounted by pivot shafts 14 and 15, respectively, as shown in FIGS. 6 and 7.

In addition, each rear swing arm 12, 13 is moved toward one side of the vehicle body center plane N, as shown in FIGS. 2, 6, and 7, in order to allow the rear wheel 11 to turn leftward. It is curved in a concave shape, and the base end of the arm 12.13 is connected to the moeki pivot shaft 1.
4 or 15 is integrally formed with the pipe portions 12a and 13a.

As shown in FIG. 1, the upper and lower ends of the rear steering arm 16 are connected to a pair of king pins 17 at the tips of the pair of rear swing arms 12 and 13 (on the vehicle body center plane N).
It is supported so that it can rotate horizontally. In addition, as shown in FIG. 2, a bearing sleeve 16a is integrally formed in the intermediate portion of this rear steering arm 16 so as to be orthogonal to the vehicle body center plane N. An axle 11a is rotatably arranged via a bearing flb. The rear wheel 11 is fixed to one end of the axle 11a that protrudes from the bearing sleeve 16a, and is supported in a cantilevered manner. Furthermore, the bearing sleeve 16
A driven sprocket 19 is rotatably disposed at the other end of the axle 11a that protrudes from the axle 11a.

As shown in FIG. 1, near the lower part of the frame vertical part 1c, there is a drive driven by an engine (not shown) mounted on the frame l in front of it via a gear mechanism (U and Z shown in the figure). A sprocket 20 is provided, and an endless chain 21 or an endless belt is wound between the driving sprocket 20 and the driven sprocket 19.

Further, the suspension unit 24 such as a Sizzic absorber,
It is interposed between a bracket 25 extending downward from near the base end of the lower side rear swing arm 13 and a bracket 23a extending rearward from the end pipe 23.

In this way, by arranging the suspension unit 24 near the base end of the lower side rear swing arm 13, the space above it can be effectively used to make it compact, and the installation time of the suspension unit 24 can be reduced. The number of parts can be reduced as much as possible, and interference with the rear wheels 11 during turning can be prevented.

As shown in FIG. 2, the first tie rod 26 has a shape in which the vicinity of both ends are each bent at a substantially right angle to one side, and then further bent at a substantially right angle so as to be parallel to the vehicle body center plane N. In other words, the rear swing arms 12, 13
Similarly, it is curved concavely to allow the rear wheel 11 to turn leftward. Further, as shown in FIG. 1, the base end of the offset lever lO is located at the lower end of the second steering shaft 5.
The distal end thereof is fixed so as to protrude from the vehicle body center plane N (FIG. 2) to the same side (here, the left side) orthogonal thereto. Then, rod ends 26a and 26b, which are a type of universal joint attached to both ends of the first tie rod 26, are attached to the offset lever lO at the lower end of the second steering sleeve 5 and the intermediate portion of the steering arm 16, respectively, to the vehicle body center plane N. (FIG. 2), the second steering shaft 5 and the rear steering arm 16 are connected by a first tie rod 26. Further, the offset ff1a of the pivot point A on the base end side (rod end 26a side) of the first tie rod 26 is set to be smaller than the offset mb of the pivot point on the distal end side (rod end 26b side) (second (See Figure and Figure 4).

In the case of this embodiment, the straight line connecting the axial center of the driving sprocket 20 and the axial center of the driven sprocket 19 is located between the pair of upper and lower rear swing arms 12, 13, so that the rear wheel U is The rear wheel 11 moves up and down using the vicinity of the axis of the drive sprocket 20 fixed to the drive sprocket 1 as a fulcrum, so even if the rear wheel 11 moves up and down, the distance between the axes of the two sprockets 19 and 20 hardly changes.

By the way, in this example, as is clear from FIG.
The pivot points E and F of the tip of the first tie rod 26 and the pair of rear swing arms 12 and 13 relative to the steering arm 16 are located on the same straight line Q when viewed from the side, and A pair of rear swing arms 1 relative to the base end side pivot point A and the frame vertical portion lc
The pivot points n and c of 2 and 13 are on the same straight line P when viewed from the side.
(here, an extension line of the second steering shaft 5), and furthermore, both the straight lines P and Q are substantially parallel, and the first tie rod 2
6 and the rear swing arms 12 and 13 are parallel to each other when viewed from the side, and form so-called parallel links. Therefore, even if the rear wheels 11 move up and down while driving, the middle part of the rear steering arm 16 will not be pushed or pulled by the first tie rod 26 due to the up and down movement, and therefore the rear steering The direction of the arm 16 (rear wheel 11) does not change. However, the present invention is not limited to this configuration, and the base end side pivot point A of the tie rod 26 and the frame vertical portion 1c
If the pivot points B and C of the pair of rear swing arms 12 and 13 are arranged on the extension line P of the second steering shaft 5, for example, the length of the first tie rod 26 can be changed, and the rear swing arms 12 and It is also possible to make the tie rod 26 slightly inclined with respect to 13.

Next, the operation mode of the above-mentioned embodiment will be explained.

In FIGS. 1 and 2, when the driver rotates the handlebar 4 in the direction in which the driver intends to proceed (for example, to the right), the first steering shaft 2 rotates clockwise and the first steering shaft 2 rotates. The offset lever 7 rotates clockwise as a fulcrum. At the same time, the offset lever 8 at the upper end of the second steering shaft 5 is pulled forward by the first tie rod 9 and rotates clockwise together with the second steering shaft 5 . At this time, the rotation angle of the second steering shaft 5 becomes equal to the rotation angle of the first steering shaft 2 because the offset amounts a of both ends of the first tie rod 9 with respect to the first steering shaft 2 and the second steering shaft 5 are equal. At the same time, the offset lever 10 at the lower end of the second steering shaft 5 also rotates clockwise about the second steering shaft 5 as a fulcrum.

As the offset lever 10 rotates, the first tie rod 26 is pulled forward and the steering arm 16 is pulled forward.
rotates clockwise around pivot points E and F with the swing arms I2 and I3, and the rear wheel 11 turns to the right. At this time, the rotation angle of the rear steering arm 16 is such that the offset Ia of the base end side (rod end 26a side) of the first tie rod 26 with respect to the second steering shaft 5 is such that the offset Ia of the first tie rod 26 with respect to the pivot points E and F of the steering arm 16 is
6, the offset amount on the tip side (rod end 26b side) is smaller than the rotation angle of the first steering shaft 2. Note that when the handlebar 4 is rotated in the opposite direction (to the left), the rear wheel it turns to the left in the same manner as described above.

FIGS. 8 to 11 show other embodiments of the present invention. The difference from the above embodiment is that the base ends of offset levers 7' and 8, which have the same offset amount, are attached to the lower end of the first steering shaft 2 and the upper end of the second steering shaft 5°, and their tips are connected to the vehicle body. In addition, the proximal end of the upper side rear swing arm 12° is attached to the intermediate part of the bifurcated vertical part 1c of the frame. , are pivotably attached to each other by a pivot shaft of 14 degrees, and the offset lever lO at the lower end of the second steering shaft of 5 degrees and the upper end of the steering arm at 16 degrees are connected by a first tie rod of 26 degrees.

Therefore, in the case of this embodiment, when the driver rotates the handlebar 4 in the direction in which he/she intends to proceed (for example, to the right), the pivot position of the first tie rod 9° changes from the first steering shaft 2 to the second steering shaft 4. Since it is opposite to the axis 5° across the vehicle center plane N, the second steering axis 5° rotates counterclockwise, and
Rear steering arm 16°, swing arm 12
The rear wheel 11 rotates counterclockwise around the pivot points E' and F with the angles E' and 13 as fulcrums, and the rear wheel 11 turns to the left in a direction opposite to that of the previous embodiment.

Also, since the first tie rod 26° is arranged above the upper side rear swing arm 12', the second steering axis 5° (
and the end pipe (23°) can be made shorter than those of the previous embodiment, making it more compact.

It should be noted that the other configurations are completely the same as those of the embodiment described above, so common constituent members are indicated using the same reference numerals as those of the embodiment described above.

By the way, in the rear wheel steering device of the present invention, the steering angle α of the rear wheel [l] during steering is the same as that of the front wheel (not shown) in the rear wheel steering device of the present invention. The proximal offset f of the second tie rod 26.26° is set so that it is considerably smaller than the steering angle β (when β = 40 to 45°, α = 2 to 3°).
The relationship between f1a and the tip side offset Ib of the second tie rod 26, 26° is set as b>&.

Although not shown, the second tie rods 2B, 2
6°The offset amounts a and b at both ends are made equal, and instead,
The same effect can be achieved even if the offset amount of the first tie rod 9.9° with respect to the first steering shaft 2 is set smaller than the offset amount with respect to the second steering shaft 5.5°. Further, in the embodiment, the first steering shaft 2 and the second steering shaft 5,
5°, the first tie rod 9.9° and the second tie rod 26 using offset levers 7.7° and 8.10.
, 26°, but instead of using such an offset lever, the first steering shaft 2 and the second steering shaft 5.5° are configured as eccentric shafts, and the tie rods are offset at 9.9° and 26.26°. The same effect can be achieved by directly pivoting the angle.

(Effects of the Invention) According to the rear wheel steering device for a two-wheeled vehicle of the present invention configured as described above, the following effects are achieved.

(1) Since the second steering shaft is provided in the middle of the steering system from the first steering shaft with the handlebar to the steering arm, each member of the steering system, such as tie rods and offset levers, can be arranged in a straight rod shape or It can be formed into a simple plate shape, making it easy to manufacture. In addition, since the steering system is constructed by combining simple-shaped structural members in the vertical and horizontal directions using joints, the displacement of each structural member when steering the rear wheels and the movement of the joints between each structural member are possible. The range is smaller, and compared to the conventional devices mentioned above, there are fewer restrictions on the placement of the steering system relative to the vehicle body, and the rear wheels can be turned symmetrically to the left and right in response to left and right rotation of the handlebar. It is easy to arrange the steering system. Furthermore, since the steering system is held by the frame at two locations, the I-st steering shaft and the second steering shaft, structural strength is also increased.

(2) With the configuration described in (1) above, most of the reaction force from the road that acts on the rear wheels and vibrations of the rear wheels during driving are absorbed by the second steering shaft, making it difficult for them to act directly on the handlebars. . Additionally, the rear wheels can be steered along with the front wheels.

(3) Even if the rear wheels move up and down, the wheelbase remains approximately constant. Additionally, since the rear wheel is supported by the steering arm in a cantilevered manner, it is easy to attach and detach the rear wheel.

[Brief explanation of the drawing]

1 to 7 show a first embodiment of the rear wheel steering device of the present invention, FIG. 1 is a left side view of the rear part of a motorcycle, and FIG. 2 is a view taken along the line ■-■ in FIG. 1. , Fig. 3 is a front view of the same, Fig. 4 is a rear view of the same, Fig. 5 is a perspective view showing the frame structure near the second steering shaft, and Fig. 6 shows the upper side rear swing arm and its pivot portion. FIG. 7 is a plan view showing the lower side rear swing arm and its pivot portion. 8 to U show a second embodiment of the rear wheel steering device of the present invention, FIG. 8 is a left side view of the rear part of the motorcycle, and FIG. 9 is an arrow indicated by the line IX-IX in FIG. FIG. 1O is a front view of the same, and FIG. 11 is a rear view of the same. 1... Frame, 2... First steering shaft, 4... Handlebar, 5.5°... Second steering shaft, 7.7°, 8.
10...Offset lever, 9.9°, 26, 26°
...Tie rod, 11...Rear wheel, 12, 12°, 1
3... Rear swing arm, 16° 16°... Rear steering arm, 24... Suspension unit.

Claims (4)

[Claims] (1) A rear steering arm, which rotatably supports a rear wheel on a cantilever, is rotatably pivoted to the tips of a pair of upper and lower rear swing arms extending rearward from the rear of the frame, and the first arm has a handlebar at its upper end. A steering shaft is supported at the front end of the frame, and a second steering shaft is supported at the rear of the frame so as to be rotatable in a substantially vertical direction, and the first steering shaft and the second steering shaft are offset from each other with respect to both shafts. A rear wheel steering device for a two-wheeled vehicle, wherein the second steering shaft is connected to the rear steering arm by a first tie rod that is offset from the second steering shaft. (2) The rear wheel steering device for a two-wheeled vehicle according to claim 1, wherein the pair of rear swing arms and the second tie rod mutually constitute a parallel link. (3) The rear wheel steering device for a two-wheeled vehicle according to claim 1 or 2, wherein the second tie rod is arranged at an intermediate position between the pair of upper and lower rear swing arms, along a power transmission device that transmits power to the rear wheels. (4) The rear wheel steering device for a two-wheeled vehicle according to claim 1 or 2, wherein the second tie rod is arranged above the pair of rear swing arms.