JPS6313828A - Front wheel suspension device of saddle seat type vehicle for rough terrain running - Google Patents

Abstract

PURPOSE:To expand the positioning space of an exhaust expansion pipe and to improve the freedom of layout, by pivoting an upper arm at a point of a body frame formed in a plain bar shape. CONSTITUTION:In a front wheel suspension device 11, an upper arm 22, a lower arm 23, a knuckle bracket 24, and a side pipe 2a compose a link of a parallelogram, the upper and the lower arms 22 and 23 move up and down responding to the uneven road surface, the knuckle bracket 24 follows to move up and down, and a shock absorber 26 absorbs the shocks then. In this case, since the upper arm 22 is formed of a single steel pipe and positioned at the front side of the shock absorber 26 of the car, no swaying member exists at the rear side of the car. Therefore, neither the swaying space nor the frame member to hold such a swaying member is necessary at the rear side, resulting in a large space there. As a result, the layout of an exhaust expansion pipe 6a can be selected freely in the space, improving the freedom of layout that much.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a front wheel suspension system for a straddle-type vehicle for traveling on rough terrain, and in particular to the arrangement of an exhaust expansion pipe when the exhaust expansion pipe is led out to the front of the vehicle. Regarding the arm shape that allows for securing installation space.

[Conventional technology]

Generally, straddle-type vehicles for driving on rough terrain have wide ultra-low pressure tires (so-called balloon tires) on the front and rear of the body frame.
It is equipped with a vehicle and the engine is mounted approximately in the center. Conventionally, as a device for suspending and supporting the front wheels, a pair of upper and lower arms are pivotally supported on the vehicle body frame, and a knuckle bracket is arranged between the tips of the two arms to form a so-called parallelogram link. There is a W Reichborn type.

In this type of vehicle, the engine is located behind the front wheel suspension system, and the exhaust pipe from the engine is generally led out to the front and then piped to the rear of the vehicle body. If this engine is a two-stroke engine, an exhaust expansion pipe of a certain capacity is required to improve the engine output and noise reduction effect, but if this exhaust expansion pipe is placed on the side of the vehicle body, this exhaust expansion pipe Since the diameter of the wheel is large, the width of the vehicle becomes wider, which poses a problem of worsening the handling of the vehicle. In order to solve this problem, there has conventionally been a model in which the exhaust expansion pipe is placed in front of the engine. In this case, there is no need to locate a large diameter exhaust expansion pipe at the rear of the vehicle body, and the vehicle Φ■ can be made narrower.

[Problem that the invention seeks to solve]

However, in a vehicle equipped with the above-mentioned W-leishbone type front wheel suspension system, the upper and lower arms of the core device have a wide shape in the longitudinal direction of the vehicle on the vehicle body pivot side when viewed from the top. A considerable amount of space is required to arrange the arm so that it does not interfere with other components when swinging. As a result, in a vehicle equipped with such a front wheel suspension system, it is difficult to secure a space necessary for arranging the exhaust expansion pipe, and there is a problem that the degree of freedom in layout of the expansion pipe is low.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a front wheel suspension system for a straddle-type vehicle for traveling on rough terrain, which can solve the above-mentioned conventional problems, expand the arrangement space of the exhaust expansion pipe, and improve the degree of freedom in the layout of the exhaust expansion pipe. The point is to provide the following.

[Means for solving problems]

The present invention provides a W-leishbone type front wheel suspension system for a straddle-type vehicle for traveling on rough terrain, in which the lower arm is formed in a substantially V-shape in plan as in the conventional case, and is pivoted at approximately the center of the vehicle body frame in the longitudinal direction of the vehicle. The upper arm is characterized in that it is formed into a substantially bar-like planar shape and is pivotally supported at one location on the vehicle body frame.

[Effect]

In the front wheel suspension system for a straddle-type vehicle for traveling on rough terrain according to the present invention, the upper arm has a substantially bar-like planar shape and is pivotally supported at only one point with respect to the vehicle body frame. The space and the swing space for this are small, and the space occupied by the upper arm is reduced, so the space for arranging the exhaust expansion pipe can be expanded (secured), and the degree of freedom in the layout of the exhaust expansion pipe is improved. .

〔Example〕

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

1 to 5 are diagrams for explaining a front wheel suspension system according to an embodiment of the present invention. In FIG. ,
The body frame 2 of the vehicle 1 connects a pair of left and right cradle-shaped side pipes 2a with 71 cross vibes 2b, and has a down tube 2d approximately in the center of each side vibe 2a, and a down tube 2d at the rear. It is a double cradle type with seat rails 2C connected. And on the top of this body frame 2, there are radiators 20 in order from the front.
．． A steering shaft 13 to which a steering handle 14 is fixed. A fuel tank 7 and a saddle-shaped seat 8 are attached, and left and right rear wheels 10 are attached to the rear via a rear arm 9a equipped with a rear wheel suspension device 9. A rear fender device 15 is disposed at the rear fender device 15 .

Further, a water-cooled two-stroke two-cylinder engine 3 is mounted approximately in the center of the vehicle body frame 2, and a carburetor 4. An air cleaner 5 is connected, and left and right exhaust pipes 6 are connected to the exhaust side. The left and right exhaust pipes 6 each include an exhaust expansion pipe 6a, a conduction pipe 6C, and a muffler 6b. This exhaust expansion pipe 6a is guided forward from the engine 3 through between the left and right down tubes 2d, and has a spiral shape of about 1.5 turns in this part, and the i-through pipe 6C. extends rearward through the fuel tank 7 and the lower left and right ends of the seat 8.

Front wheels 12 with balloon tires are mounted on the front left and right sides of the vehicle body frame 2 via a front wheel suspension system 11, and above the left and right front wheels 12, a front fender device 16 is disposed. has been done.

The front wheel suspension system 11 includes an upper arm 22 and a lower arm 2.
This is a W rice bone type in which a knuckle bracket 24 is arranged between the tip portions of 3.

The lower arm 23 is formed by arranging two steel pipes in a V-shape in plan view, and a lower joint part 23a that supports a lower joint part 25a is formed in the mating part.

At two locations at the base of this lower arm 23 are lower pivot attachment portions 23.
b is formed, which is swingably supported by the lower pivot bracket 2e, and the two lower pivot brackets 2e,'
le are formed at the lower side of the side pipe 2a at predetermined intervals in the longitudinal direction of the vehicle.

The upper arm 22 is formed by bending a single steel pipe into a planar substantially dogleg shape, and has an upper jig int part 22a supporting the upper jig int 25b formed at its tip, and this lower jig int part 22a supports the lower jig int part 22a. It is located almost directly above the jig point portion 233.

An upper pivot portion 22 is provided at one location at the base of the upper arm 22.
b is formed, which is swingably supported by an upper pivot bracket 2f, and this upper pivot bracket 2f is connected to a support pipe 2g fixed between the upper and lower sides of the side pipe 2a.
and the vertical side of the side pipe 2a. The upper pivot bracket 2f is located approximately directly above the lower pivot bracket 26 on the front side.

Further, a lower end portion of a shock absorber 26 is pivotally supported on the upper surface of the lower arm 23, and this shock absorber 26 is attached to the upper surface of the upper arm 23.
The support bracket 2 extends upward passing slightly behind the side pipe buoy 2a, and its upper end is fixed to the upper side of the side pipe buoy 2a.
It is supported by 1. Further, a tie rod 27 is arranged behind the shock absorber 26 so as to face the vehicle width direction, and although not shown, this tie loft 27 connects the knuckle bracket 24 and the lower end of the steering shaft 13. are doing.

Next, the effects of this embodiment will be explained.

In the front wheel suspension system 11 of this embodiment, an upper arm 22, a lower arm 23 . Knuckle bracket 24 and side pipe 2
a forms a parallelogram-shaped link, and the upper and lower arms 22, 23 swing up and down according to the unevenness of the road surface, and the knuckle bracket 24 moves up and down accordingly. A shock absorber 26 absorbs the shock. In this case, in this embodiment, the upper arm 22 is formed of one steel pipe and is arranged on the front side of the vehicle of the shock absorber 26, so there is no swinging member on the rear side of the vehicle. Since no rocking space is required in the side parts and, of course, no frame member for supporting the rocking member is required in this rear part, a large space is created in the rear part. As a result, the exhaust expansion pipe 6a can be freely laid out in this space, and the degree of freedom in layout is improved accordingly.

Note that in the above embodiment, the upper arm 22 is arranged in front of the shock absorber 26, but in the present invention, this upper arm does not necessarily have to be arranged in the front side, and in short, it is only necessary to form the upper arm into a planar substantially rod shape. .

Furthermore, although the above embodiments have been described with reference to a two-cylinder engine, the present invention can of course also be applied to a single-cylinder engine with one exhaust expansion pipe, and has the effect of facilitating the layout of the exhaust expansion pipe. .

〔Effect of the invention〕

As described above, according to the front wheel suspension system for a straddle-type vehicle for traveling on rough terrain according to the present invention, the upper arm is formed into a planar substantially rod shape,
Since the upper arm is pivoted at point IIm of the vehicle body frame, the space for placing the upper arm and the swinging space are narrow, which expands the space for placing the exhaust expansion pipe, and improves the degree of freedom in the layout of the expansion pipe. There is.

[Brief explanation of drawings]

1 to 5 are diagrams for explaining a front wheel suspension system according to an embodiment of the present invention, in which FIG. 1 is a plan view of the front wheel suspension section, FIG. 2 is a front view thereof, and FIG. 4 is a side view of the front wheel suspension attachment portion of the vehicle body frame, FIG. 4 is a side view of a straddle type vehicle for traveling on rough terrain to which the above embodiment is applied, and FIG. 5 is a plan view thereof. In the figure, l is a saddle type vehicle for traveling on rough terrain, 2 is a body frame, 3 is an engine, 6a is an exhaust expansion pipe, 11 is a front wheel suspension, 12 is a front wheel, 22 is an upper arm, 23 is a lower arm, 26 is a buffer. Patent applicant Yamaha Motor Co., Ltd. Agent
Patent Attorney Tsutomu Shimofu Figure 1 Figure 2 7.16

Claims (1)

[Claims] (1) Straddle type for riding on rough terrain, with front wheels with wide ultra-low pressure tires mounted on the front left and right sides of the vehicle body frame, an engine mounted approximately in the center in the front-rear direction, and an exhaust expansion pipe guided forward from the engine. In the vehicle, the bases of a pair of upper and lower arms are pivotally supported on the front left and right sides of the vehicle body frame, respectively, and a knuckle bracket is disposed between the tips of the upper and lower arms, A front wheel suspension device in which each of the front wheels is supported by the knuckle bracket and a shock absorber is disposed between the lower arm and the vehicle body frame, the lower arm being formed into a substantially V-shape in plan view; A front wheel suspension system for a straddle-type vehicle for traveling on rough terrain, characterized in that the upper arm is pivoted at two locations in the longitudinal direction of a vehicle body frame, the upper arm is formed into a planar substantially bar shape, and is pivoted at one location on the vehicle body frame.