JPS61257382A - Chain drive of car for travelling on uneven ground - 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] (Industrial Application Field) The present invention has a rear arm that holds one driving rear wheel with a wide ultra-low pressure tire so that it can move up and down, and drives the rear wheel with one chain. The present invention relates to a chain drive device applied to a vehicle for traveling on rough terrain.

(Background of the Invention) There are two-wheeled vehicles and three-wheeled vehicles in which a wide ultra-low pressure tire (so-called balloon tire) is mounted on one rear wheel, and this rear wheel is held by a rear arm so that it can move freely. When the rear wheels of this type of vehicle are driven by a single chain using an engine, it is conceivable to configure the vehicle like a normal motorcycle. That is, it is conceivable to position the body frame on the outside of the chain in the vehicle width direction, so that the bearing portion of the rear arm penetrates the chain running surface in the vehicle width direction. By arranging the vehicle body frame on the outside of the chain in the vehicle body width direction in this manner, the width of the bearing portion of the rear arm can be increased and the torsional rigidity of the rear arm can be increased.

However, when this configuration is adopted for a vehicle with wide tires, the width of the body frame becomes wider near the rear arm's body side bearing, and when the driver is seated on the straddle-type driver seat, the distance between the left and right stationary stands increases. becomes larger. This causes a problem in that it becomes difficult to take a comfortable riding position.

Also, because the diameter of wide ultra-low-pressure tires is relatively small, the rear sprocket must also be made small in diameter. For this reason, if the vehicle body side bearing portion of the rear arm passes through the chain running surface, there is a problem in that the chain tends to interfere with the bearing portion of the rear arm when the rear wheel moves up and down significantly.

(Purpose of the Invention) The present invention was made in view of the above circumstances, and it solves the problem that if the width of the vehicle body frame is excessively large when driving one rear wheel with a wide ultra-low pressure tire with one chain. figure,
To provide a chain drive device for a vehicle for traveling on rough terrain, which allows a comfortable driving posture and prevents a vehicle body side bearing part of a rear arm from interfering with the chain.

(Structure of the invention) According to the invention, this object is achieved by:
It is equipped with two driving rear wheels, one or two steering front wheels, an engine mounted near the center of the vehicle body, and a straddle-type driver seat arranged at the top of the vehicle body, and the rear wheels are moved up and down by rear arms. In an all-terrain vehicle that transmits the output of the engine to the rear wheels by a single chain, the rear arm has a bearing section and a vehicle body frame side holding section that holds the bearing section; This is achieved by a chain drive device for a vehicle for traveling on rough terrain, which is located closer to the center in the vehicle width direction than the chain.

(Example) Fig. 1 is a plan sectional view of the main parts of a two-wheeled vehicle for traveling on rough terrain, which is an embodiment of the present invention, Fig. 2 is a side view of the main parts, and Fig. 3 is a plan view of the main parts of the two-wheeled vehicle. FIG.

In these figures, the reference numeral 10 denotes a vehicle body frame, which includes a steering shaft cylinder 12, one main tube 14 extending rearward from the steering shaft cylinder 12, and a pair of left and right down tubes 16 (16
a, 16b), a bracket 18 that connects the rear end of the main tube 14 to the down tube 16, and this bracket) 1
A pair of left and right seat rails 20 (only one shown) extends rearward from the down tube 16.
A pair of left and right pack tubes 22 (only one shown) is provided. A balloon-shaped bracket 26 that opens forward when viewed from above is fixed to the rear end of the down tube 16.

24 is an engine mounted near the center of the vehicle body frame 10, and is fixed to the down tube 16 and the bracket 26. In FIG. 1, 28 is a long bolt that fixes the engine 24 to the down tube 16, and 30 is a bracket 26.
It is a long bolt that is fixed to the

32 is a rear arm. This rear arm 32 has a substantially triangular side surface, and a bearing portion 34 (34a, 3
4b) is pivoted to the bracket 26. That is, the bracket 26 serves as a holding portion for the bearing portion 34 of the rear arm 32. Bracket 2 as this holding part
A pivot shaft 36 passes through the rear arm 6, and bearing portions 34 of the rear arm 32 are held at both ends of the pivot shaft 36 so as to be able to swing up and down.

A rear wheel 38 is held at the rear end of the rear arm 32.

The rim 38a of this rear wheel 38 has a wide ultra-low pressure tire 38b.
is installed.

The rear end of a shock absorber 40 arranged substantially horizontally is pivoted to the upper end of the rear arm 32, and the front end of this shock absorber 40 is pivoted to the bracket 18.

42 is a chain that transmits the output of the engine 24 to the rear wheels 38. This chain 42 is connected to the output shaft 44 of the engine 24.
(Fig. 1) The sprocket 46 fixed to the rear wheel 38
It is wound around a sprocket 48 fixed to.

The bearing portion 34 of the rear arm 32 and the vehicle body frame 10
The bracket 26 which is the side holding part is the chain 4
It is located closer to the center in the vehicle width direction than 2.

In FIG. 3, reference numeral 50 indicates a front fork rotatably held by the steering shaft cylinder 12 to the left and right, 52 indicates a front steering wheel with a wide ultra-low pressure tire attached to its lower end, and 54 indicates a steering bar handle. , 56 is a fuel tank attached to the tube 14, 58 is a straddle type driving seat attached to the seat rail 20 on the upper part of the vehicle body, 60 is a front fender, 62 is a rear fender, 64 is an exhaust pipe, 66 is a muffler, 68° 70 is a cover for protecting the chain 42. Further, 72 (72a, 72b) is a pair of left and right footrests, which are fixed to the engine 24.

According to this embodiment, the bearing part 34 of the rear arm 32 and the bracket 2 on the vehicle body frame 10 side that supports this bearing part
The width of 6 etc. becomes narrower. As a result, the width of the vehicle body frame 10 does not become excessively large, and when the driver sits on the straddle type driving seat 58, the vehicle body frame 10 does not hit the driver's legs, and the driver can ride in a comfortable posture. Further, since the bearing part 34 and the bracket 26 do not overlap the running surface of the chain 42, even if the chain 42 moves up and down as the rear wheel 38 moves up and down, there is no risk that the chain 42 will interfere with the bearing part 34 and the bracket 26. Furthermore, since the rear wheel 38 is wide,
Even if the bearing part 34 and the bracket 26 that supports it are located inside the chain 42 in the vehicle body width direction, the bearing part 3
4 and the width of the bracket 26 will not become excessively small, and problems such as a decrease in the torsional rigidity of the rear arm 32 will not occur.

Although the above embodiments apply the present invention to a two-wheeled vehicle for traveling on rough terrain, the present invention also includes an application to a three-wheeled vehicle having two steerable front wheels and one rear wheel. . In addition, the output shaft 44 has its tip in the vehicle width direction connected to the sprocket 46.
It is preferable that the output shaft 44 be supported by a cover via a bearing (not shown) because the bending moment applied to the output shaft 44 will be reduced.

Since the supporting part on the vehicle body frame side that supports the bearing part and the bearing part is located closer to the center of the vehicle body in the width direction than the chain, the width of the vehicle body frame does not become excessively wide, and it is possible to ride in a comfortable posture. Furthermore, even if the rear wheel moves up and down significantly, there is no risk of the chain interfering with the bearing or support section.

[Brief explanation of drawings]

Fig. 1 is a plan cross-sectional view of the main parts of a two-wheeled vehicle for traveling on rough terrain, which is an embodiment of the present invention, Fig. 2 is a side view of the same main parts, and Fig. 3 is a side view of this two-wheeled vehicle. be. DESCRIPTION OF SYMBOLS 10... Body frame, 24... Engine, 26... Bracket as a support part, 32... Rear arm 34... Bearing part, 38... Rear wheel, 38b... Wide ultra-low pressure tire , 42... Chain, 58... Straddle type driver's seat.

Claims (1)

[Scope of Claims] One driving rear wheel and one or two steering front wheels with wide ultra-low pressure tires, an engine mounted near the center of the vehicle body, and a straddle-type vehicle mounted on the upper part of the vehicle body. a driver's seat, wherein the rear wheel is held movably up and down by a rear arm, and the output of the engine is transmitted to the rear wheel by a single chain; A chain drive device for a vehicle for traveling on rough terrain, characterized in that a body frame side holding part that holds the chain is located closer to the center in the vehicle width direction than the chain.