JPH0411593A - Motorcycle - Google Patents

Abstract

PURPOSE:To increase the degree of freedom in piping and reduce the manufacturing cost by arranging a swing arm in cantilever form on one side of a rear wheel and arranging an exhaust pipe expansion part in the space obtained in cantilever form. CONSTITUTION:A swing arm 20 is supported in swingable manner at the rear part of a frame 11, and a rear wheel 21 whose axle is inserted into an eccentric cam cylinder 28 in the rear part is cantilever-supported on one side. The chambers 31a and 32a having the spread diameter of the exhaust pipes 31 and 32 which are connected with the engine cylinder parts 29 and 30 are arranged in the space obtained by the cantilever type swing arm 20. The mufflers 33 and 34 behind the exhaust pipe are extended to the other side of the rear wheel 21. Accordingly, the large degree of freedom in the arrangement position of the exhaust pipes 31 and 32 is obtained, and arrangement at the position where the bank angle is not restricted is permitted free from bending, and the manufacturing cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a motorcycle, and particularly to a motorcycle equipped with a two-stroke engine.

(Prior art) It is known that the output of a two-stroke engine can be improved by expanding the diameter of the middle part of the exhaust pipe to form a chamber section (expansion section) with a large volume. However, various exhaust pipes in which a chamber portion is formed are in practical use. In such a motorcycle, the exhaust pipe is extended rearward from the engine and the chamber portion is placed in a position where it does not interfere with the swing arm, but the chamber portion has a bank angle of f! This could be a factor in limiting ILJ.

Therefore, the applicant has previously proposed an exhaust pipe arrangement structure in which the bank angle is not restricted depending on the chamber part (
(Japanese Unexamined Patent Publication No. 63-212194). In this exhaust pipe arrangement structure, the exhaust pipe is curved and the chamber portion is located below the engine.

(Problems to be Solved by the Invention) However, the above-mentioned exhaust pipe arrangement structure of JP-A No. 63-212194 has a problem in that the exhaust pipe is curved, which requires complicated processing, leading to an increase in manufacturing costs. was there.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a motorcycle that does not limit the bank angle at a low cost.

(Means for Solving the Problems) An exhaust pipe arrangement structure for a motorcycle according to the present invention includes a structure in which a rear wheel is swingably supported on a vehicle body via a swing arm,
In a motorcycle in which a two-cycle engine is mounted on the vehicle body in front of the rear wheel, and an exhaust pipe having an expanded diameter part in the middle extends from the engine to the swing arm side, the swing arm is connected to the rear wheel. The key point is that the exhaust pipe is disposed on one side in the vehicle width direction, and at least a part of the expansion portion of the exhaust pipe is located on the other side of the rear wheel.

(Function) In the motorcycle according to the present invention, the rear wheel is supported by a cantilevered swing arm disposed on one side of the vehicle body, a considerable space is secured on the other side of the vehicle body, and the expansion portion is installed in this space. position and place the exhaust pipe on the other side of the vehicle body. Therefore, there is great freedom in the arrangement of the exhaust pipe, the expansion part can be placed in a position that does not limit the bank angle and does not interfere with the swing arm, and the exhaust pipe does not have to be curved. It can be arranged easily and manufacturing costs can be reduced.

In addition, in a motorcycle equipped with an engine having a plurality of cylinders and having exhaust pipes extending rearward from these cylinders, each exhaust pipe is arranged on the other side of the vehicle body. It is also possible to obtain a large degree of freedom by determining .

(Example) Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show the exhaust pipe arrangement structure of a motorcycle according to an embodiment of the present invention, in which FIG. 1 is a side view of the motorcycle, FIG. 2 is a plan view of the main parts, and FIG. FIG. 3 is a rear view of main parts.

In the figure, 11 is the main frame, 12 is the spare part,
14 is a seat pipe, 15 is a front fork, 16 is a front wheel, 17 is a handle, 18 is a fuel tank, 19 is a seat, 20 is a rear swing arm, 21 is a rear wheel, 22 is 2
Cycle V type 2 cylinder engine, 23 is a cushion unit, 24 is a left and right step, 42 is a change pedal,
43 is a brake pedal. In addition, in FIG. 3, B indicates the maximum allowable bank angle.

As clearly shown in FIG. 2, the swing arm 20 is made up of a main arm 25, a sub arm 26, a mounting pipe 27, and a split line type eccentric cam cylinder 28, and the front end of the main arm 25 and the sub arm 26 are connected to each other. The front end is connected to the mounting pipe 27 by welding or the like, the main arm 25 extends rearward on the left side of the rear wheel 21, the tail pipe 28 is connected to the rear end by welding or the like, and the sub arm 26 is bent into a substantially hook shape. The rear end of the sub arm 26 is offset and connected to the upper inner side of the intermediate portion of the main arm 25 by welding or the like. A bell crank 44 is attached to the above-mentioned sub arm 26.
are swingably connected, and the sub arm 26 is connected to a bell crank 44.
and to the frame 11 via the tension rod 45,
Also, the cushion unit 2 is connected to the cushion unit 2 via the bell crank 44.
It is connected to 3. The swing arm 20 is swingably supported at the rear of the frame 11 by having a pivot shaft (not shown) inserted into a mounting pipe 27, and an axle shaft (not shown) inserted into an eccentric cam cylinder 28 to support the rear wheel 21 in a cantilevered manner. .

The engine 22 has two cylinder parts 29 and 30 arranged in an upper and lower V shape when viewed from the side, and exhaust pipes 31 and 32 are connected to these cylinder parts 29 and 30, respectively. As clearly shown in FIG. 2, the exhaust pipe 31 connected to the upper cylinder section 29 is gently bent in a convex shape to the left below the engine 22, and extends from below the engine 22 to below the front of the swing arm 20. A chamber portion 31a is formed with an enlarged diameter, and is guided to the right from this chamber portion 31a, rising upward behind the sub arm 26 of the swing arm 20, and extending rearward and diagonally upward on the right side of the rear wheel 21. . Further, the exhaust pipe 32 connected to the lower cylinder section 30 is gently bent in a substantially S-shape below the engine 22 to form a chamber section 32a whose diameter increases from below the engine 22 to below the front of the swing arm 20. It rises from below the engine 22 behind the auxiliary arm 26 of the swing arm 2° and extends rearward and diagonally upward on the right side of the rear wheel 21. As shown in FIG. N1 and FIG. 2, the rear part of the chamber portion 32a of the exhaust pipe 32 is located on the right side of the rear wheel 21 when viewed from the side, and the exhaust pipes 31 and 32 are located in the chamber portion 31a.

32a are arranged so as to be separated from each other in the front and rear and left and right directions. Note that 33 and 34 are silencers provided at the rear ends of the exhaust pipes 31 and 32, and these silencers 33 and 34 are fixed to each other, and the silencer 34 is supported by the seat vibe 14 via the stay 41. There is.

In such a motorcycle, the rear wheel 21 is supported by a cantilever type swing arm 20 in which the main arm 25 extends to the left side of the rear wheel 21, and the swing arm 20 is of a cantilever type. The exhaust pipes 31 and 32, especially the chamber portion 31a, are located in the space.

32a. Therefore, great freedom is gained in determining the location of the exhaust pipes 31 and 32, and as is clear from FIG. tube 31.32
It is easy to process and the manufacturing cost can be reduced. In FIG. 3, an exhaust pipe H shown by a phantom line represents an example of measures taken to ensure a bank angle in a conventional motorcycle.

In particular, in this embodiment, since the exhaust pipes 29.30 extending from the two cylinder parts 29.30 of the engine 22 are arranged vertically on the right side opposite to the swing arm 20, the chamber part 31a, It is easy to shift the position of the exhaust pipes 31 and 32 back and forth, and a greater degree of freedom can be obtained by determining the positions of the exhaust pipes 31 and 32.

In the above embodiment, a two-cylinder engine 22 with two exhaust pipes 31 and 32 connected is illustrated, but it goes without saying that the present invention is also applicable to a multi-cylinder engine with a larger number of exhaust pipes connected. Nor.

(Effects of the Invention) As explained above, according to the motorcycle according to the present invention, the rear wheel is supported by the single-sided swing arm, and the space obtained by making the swing arm single-sided is utilized. Since the expansion part of the exhaust pipe is arranged in a straight line, there is great freedom in the arrangement position of the exhaust pipe, and the exhaust pipe can be placed in a position that does not limit the bank angle without bending, reducing the manufacturing cost of the exhaust pipe. can be reduced.

In particular, in the motorcycle according to the embodiment described above, since the plurality of exhaust pipes are arranged vertically and isolated on the same side of the vehicle body,
By shifting the positions of the chamber parts relative to each other, greater freedom can be obtained in the arrangement of the exhaust pipes.

[Brief explanation of the drawing]

Figures 1 to 3 show a motorcycle according to an embodiment of the present invention, with Figure 1 being a side view of the motorcycle, Figure 2 being a plan view of the main part, and Figure 3 being a rear view of the main part. It is. l... Main frame 12... Head vibe 4
...Seat vibe 5...Front fork 0...Rear swing arm...f&%i 22...Engine 5...
・Main arm 29.30-・Cylinder part 1.32・・
・Exhaust pipe Ia, 32a...Chamber part (expansion part) patent

Claims (2)

[Claims] (1) A rear wheel is swingably supported on the vehicle body via a swing arm, a two-cycle engine is mounted on the vehicle body in front of the rear wheel, and an exhaust pipe is installed with an expansion part with an enlarged diameter in the middle. In a motorcycle in which the swing arm extends from the engine to the side of the swing arm, the swing arm is arranged on one side of the rear wheel in the vehicle width direction, and at least a part of the expansion part of the exhaust pipe is arranged on the other side of the rear wheel. A two-wheeled motor vehicle characterized by being positioned. (2) In the motorcycle according to claim 1, the engine has a plurality of trachea, and each of these cylinders is connected to an exhaust pipe having an expansion part, and both of these exhaust pipes are connected to the other side of the vehicle body in the vehicle width direction. A motorcycle characterized by extending rearward.