JPS6025870A - Motorcycle for desert travelling - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motorcycle for running on rough terrain, in which a rear wheel equipped with a wide low-pressure tire is vertically supported by a swing arm.

Motorcycles are being considered that have wide, low-pressure tires (so-called balloon tires) mounted on the rear wheels to improve rough road drivability. This type of vehicle has large rear wheels, so when using chain drive, it is necessary to install an intermediate shaft between the engine and the rear wheels to reduce the engine width and allow driving in a comfortable position. Conceivable. In this case, if the chain (first chain) that is wrapped around the engine side sprocket and intermediate shaft side sprocket installed on the engine output shaft is too short, its durability will deteriorate significantly and adjustment of chain tension will become difficult. . Additionally, in order to ensure a large vertical movement range (wheel travel) for the rear wheels, it is desirable to make the swing arm as long as possible.

The present invention has been made in view of these circumstances, and involves lengthening the (first) chain that transmits engine rotation to the intermediate shaft provided between the engine and the rear wheel. To provide a motorcycle for running on rough terrain that has improved durability, facilitates tension adjustment, and has a longer swing arm to increase the vertical movement range of the rear wheel.

In order to achieve these objects, the present invention provides an intermediate shaft in the swing arm, and arranges the engine output shaft in front of the pivot shaft of the swing arm, and the intermediate shaft in the rear of the pivot shaft. That is, in a motorcycle for flying over rough terrain in which a rear wheel equipped with a wide low-pressure tire is supported by a swing arm so as to be movable up and down, the intermediate shaft is attached to the swing arm so as to be located behind the pivot shaft of the swing arm, and the pivot shaft is mounted on the swing arm. The vehicle includes a first chain that transmits the rotation of the engine output shaft located in front of the intermediate shaft to the intermediate shaft, and a second chain that transmits the rotation of the intermediate shaft to the rear wheels. The present invention will be described in detail below based on the illustrated embodiments.

Fig. 1 is a side view of an embodiment of the present invention, Fig. 2 is a plan view showing the rear wheel drive mechanism, Fig. 3 is a right side view showing the vicinity of the first chain, and Fig. 4 is an explanation of the principle. It is a diagram.

In FIG. 1, reference numeral 10 denotes a cradle-type frame, and a steering shaft cylinder 12. Main tube 14. Down tube 16.
Lower tube 1.8.18. Seaback tube 24
．． 24 mag. 26 is the front fork, and 28 is the front wheel equipped with wide low-pressure tires.

30 is a steering wheel, 32 is a fuel tank, and 34 is a driver's seat. The engine 36 is mounted on the lower tube 18. A bracket 38.38 is fixed to the bottom of the seat pillar tube 20°20, and 40 is a swing arm, which has a pair of left and right arms, the distance between which widens at the rear, and between which a rear wheel with a wide low-pressure tire is attached. 42 is rotatably supported. In Figure 2, 44 is this rear wheel 4.
2 is a rear wheel side sprocket that drives the rear wheel, and 46 is a brake. The front part of the swing arm 4o is made narrow.

Its front end is held by a pivot shaft 48 supported by the brackets 38 and 38 so as to be able to swing vertically.

Note that the rear end portion of the engine 36 is also supported by this pivot shaft 48 .

The intermediate shaft 5o is laterally inserted through a narrow portion of the swing arm 40 at the rear of the pivot shaft 48.

It is rotatably supported by a bearing 52154 (FIG. 2). Reference numerals 56 and 56 denote a pair of left and right footrests, which are fixed to the lower part of the seat pillar tube 20 so as to protrude outward.

A sprocket (60, 62) is fixed to the right end of the output shaft 58 (FIGS. 2 and 4) of the engine 36 and the intermediate shaft 50.
A chain 64 is wrapped around it. This chain 64
pass above and below a guide roller 66 rotatably supported by a pivot shaft 48.

In this embodiment, the chain winding radius R1 of the engine side sprocket 60 is the same as the chain winding radius R2 of the intermediate shaft side sprocket 62, and the chain winding radius R3 of the guide roller 66 is larger than these R1 and R2 (the fourth figure). The intermediate shaft side sprocket 62 is swung by the swing arm 40 so that it is located within an extension of a line (external tangent) that circumscribes the circles of the chain winding radii R1 and R3 of the sprocket 60 and the guide roller 66. The range of motion is determined.

In FIG. 4, the broken line and the dashed-dotted line indicate the swing limits of the sprocket 62, and 2θ indicates its swing angle range.

As a result, for example, if the sprocket 62 rotates clockwise by 0 radians based on the solid line position in FIG.
Arc A which is the chain contact length on the upper side of the guide roller 66
A' is shorter by R3Xθ and the total length surrounding the spout 60, 62 and guide roller 66 does not change. Therefore, the slack of the first chain 64 is always kept constant and does not change depending on the swing angle of the swing arm 40.

The left end of the intermediate shaft 50 protrudes outward from the left seat pillar tube 20, and a sprocket 68 is fixed to the tip thereof. A second chain 70 is wound around this sprocket 68 and the sprocket 44 of the rear wheel 42. Therefore, the vehicle body center axis C of the first chain 64 (second
The distance D from the center axis C of the second chain 70 is smaller than the distance E from the vehicle body center axis C of the second chain 70.

Reference numeral 72 denotes a buffer unit, the front end of which is pivotally supported by the main tube 14, and the rear end pivotally attached to one end of a lever 74 bent at a substantially right angle. The other end of the lever 74 is pivotally supported between both seat pillar tubes 20°20. Further, the intermediate portion of the lever 74 is connected to the swing arm 40 by a bushing link 76.

In the above embodiment, the rotation output of the engine 36 is transmitted to the intermediate shaft 50 via the first chain 64, and the rotation of the intermediate shaft 50 is transmitted to the rear wheel 42 via the second chain 70. Further, when an upward impact is applied to the rear wheel 42 from the road surface, the swing arm 40 swings about the pivot shaft 48, the bushing IJ 76 pushes the lever 74, and the buffer unit 72 is compressed. The intermediate shaft 50 is a footrest 56
Since it is located at the rear of the footrest 56, when the driver places his or her feet on the footrest 56.

The heel of the foot is the middle axis 50. Does not interfere with sprocket 68. Further, the first chain 64 is connected to the seat pillar tube 2.
Since the guide roller 66 is wrapped around the inner side of the vehicle so as to sandwich it from below, it can be placed close to the vehicle body center axis C without interfering with the pivot shaft 48. Therefore, the distance between the footrests 56° and 56 and the width of the engine 36 can be reduced.

This allows you to take a comfortable driving position.

Since the intermediate shaft 50 is behind the pivot shaft 48.

The first chain 64 is relatively long, increasing the durability of the chain 64. It also becomes easier to adjust the length of the chain 64 by increasing or decreasing the number of pieces. In particular, when the intermediate shaft 50 is made adjustable back and forth on the swing arm 40, its movable range can be widened, and the tension of the chain 64 can be adjusted even better.

On the other hand, since the pivot shaft 48 can be brought sufficiently close to the engine 36, its length can be ensured to be long and the range of vertical movement of the rear wheel 42 can be increased.

In this embodiment, the swinging range of the swing arm 40 is adjusted so that the intermediate shaft sprocket 62 is located within the range between the outer tangents of the circle formed by the chain winding diameters of the engine sprocket 60 and the guide roller 66. is regulated, the amount of slack in the first chain 64 does not change due to swinging of the swing arm 40. This eliminates the need for a chain tensioner with a complicated structure.

Furthermore, in this embodiment, since the guide member is rotatably provided on the pivot shaft 48, the movement of the first chain 64 becomes very smooth.

As described above, in the present invention, the intermediate shaft is provided on the swing arm, and the pivot shaft is positioned between the engine side sprocket and the intermediate shaft side sprocket.

The first chain becomes sufficiently long, its durability improves, and tension adjustment becomes easier. Also, the pivot shaft can be brought close enough to the engine.

By lengthening the swing arm, the range of vertical movement of the rear wheels can be increased, making the vehicle even more suitable for driving on rough roads.

[Brief explanation of drawings]

Fig. 1 is a left side view of an embodiment of the present invention, Fig. 2 is a plan view showing the rear wheel drive mechanism, Fig. 3 is a right side view showing the vicinity of the first chain, and Fig. 4 is an explanation of the principle. It is a diagram. 40...Swing arm, 42. Rear wheel. 48... Pivot axis, 50... Intermediate axis. 58... Engine output shaft, 64... First chain. 70...Second chain. Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Yama 1) Text: Written Amendment September 2, 1980 Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office 1. Indication of IS Patent Application No. 131853 1988 2 Invention Name of Motorcycle for Riding on Rough Land 3, Relationship with the Amendment Case Patent Applicant Address Shizuoka Clause U” 2500 Shintada, City Name (A
O7) Yamaha Motor Co., Ltd. Representative: Hideto Eguchi 4, Agent address: 6-21 Nishi-Shinbashi 1-chome, Minato-ku, Tokyo Number of inventions increased by the amendment: 0 7, Drawings subject to the amendment: 8 Contents of the amendment The drawings will be inscribed. There are no amendments to the content.

Claims (1)

[Claims] In a motorcycle for driving on rough terrain, the rear wheel equipped with wide low-pressure tires is supported by a swing arm so that it can move up and down.
an intermediate shaft attached to the swing arm so as to be located behind the pivot shaft of the swing arm; a first chain that transmits the rotation of the engine output shaft located in front of the pivot shaft to the intermediate shaft; A motorcycle for traveling on rough terrain, comprising: a second chain that transmits rotation to a rear wheel.