JPS6282217A - Exhaust pipe device for motorcycle - Google Patents

Abstract

PURPOSE:To shorten the overall length of an exhaust pipe while securing the length of an exhaust passage, by forming the exhaust pipe taken out beneath from an engine into a roll in almost curl-shaped form at a lower surface of the engine, and connecting it to a muffler at the lower side of a body frame. CONSTITUTION:After the exhaust pipe 8 connected to a lower surface of an engine 7 is taken out beneath from the lower surface of the engine 7, once it is bent to the rear, and then it is turned to the front and, after forming one plane surface into a roll in almost curl-shaped form along a bottom surface of the engine 7, it is connected to a muffler 9 at the lower side of a body frame 2. With this constitution, the overall length of the exhaust pipe is reducible without shortening the length of an exhaust passage.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to motorcycles, especially scooters, movettes, etc.
The present invention relates to an exhaust pipe device suitable for an underbone type vehicle, and relates to an exhaust pipe device for a forward-inclined engine arranged between a front wheel and a rear wheel.

[Conventional technology and its problems]

Conventionally, under-beef type vehicles often use forward-slanted engines in which the axis of the cylinder is installed upward by about 10 degrees from the horizontal, and the exhaust pipe is directed from the engine toward the lower side of the vehicle body. The exhaust n1 is then turned toward the rear and connected to an exhaust muffler installed at the rear.

On the other hand, engines require a relatively long exhaust pipe length in order to operate efficiently, but in engines such as forward-leaning engines where the exhaust pipe connection is installed close to the ground, it is difficult to achieve the desired exhaust passage. If you don't get the length, the exhaust pipe will protrude to the rear of the muffler. On the other hand, if the exhaust pipe is shortened, the desired engine output may not be achieved.

[Object of the invention, outline of the structure]

The purpose of this invention is to eliminate the above-mentioned problems and provide an exhaust pipe device that has a sufficient length of the exhaust passage and does not require the exhaust pipe to extend long toward the rear of the vehicle. The exhaust pipe is taken out downward from the engine, which is supported by the car body frame, and is bent backwards, then turned forward, and wrapped around once on a flat surface, and then attached to the car body. It is connected to a silencer installed on the lower side of the frame.

[For production]

The exhaust pipe is formed so that it wraps around the bottom of the engine, so the length of the passage can be increased.
Moreover, the length of the vehicle body in the longitudinal direction can be kept relatively short.

〔Example〕

The present invention will be explained below with reference to the illustrated embodiment. In the figure, reference numeral 1 denotes a moped, and a front wheel 4 is supported at the front end of an underbone type vehicle body frame 2 via a front fork 3 so as to be able to turn left and right. At the rear, a rear arm 5, which also serves as an axis tube for a drive shaft (not shown) that connects an engine 7 and a rear wheel 6, which will be described later, is pivotably supported so as to be able to swing up and down. 07 on which the rear wheel 6 is supported is the front wheel 4
The engine is suspended between the rear wheels 6 and the rear wheels 6, and in this example, it is a forward-inclined single-cylinder air-cooled two-stroke engine. 8 is an exhaust pipe connected to the bottom surface of the engine 7, and after being taken out from the bottom surface of the engine T, it is bent backwards, then turned forward, and is placed on one plane along the bottom surface of the engine 7. After approximately one winding in the shape of a "", it is connected to the silencer 9 provided on the lower side of the vehicle body frame 2. The exhaust pipe 8 includes a constant cross-sectional area portion 8a connected to the engine 7, and an expanding portion 8b whose cross-sectional area gradually increases, which is welded to the rear end of the constant cross-sectional area portion 8a. Deoshi, constant cross-sectional area part 8
Is the nose made of steel? As shown in FIG. 5, the expansion portion 8b is an upper and lower half portion 8A made of two press-formed steel plates.

8B are polymerized and welded at their edges 8D, and the diameter gradually expands from the front end, and then has a relatively long, thick, low cross-sectional area at the rear, and the rear part gradually narrows to form a male. and is connected to a silencer 9.

The lower half 8B has an inverted triangular bottom, and its cross-sectional shape is approximately pentagonal. Therefore, consideration has been given to making the thick inflated portion 8b appear thinner by reducing the portion visible from the eye position.

〔Effect of the invention〕

As described above, in this invention, the exhaust pipe taken out downward from the engine is wrapped around the bottom surface of the engine in a shape of approximately "2", and then connected to a silencer provided on the lower side of the vehicle body frame. Therefore, the total length of the exhaust pipe can be shortened without shortening the length of the exhaust passage. Furthermore, as shown in the example, by covering the bottom surface of the engine with the exhaust pipe, it is possible to protect the engine from flying stones and clods even when the vehicle is driving on rough roads. be.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a side view of the motorcycle, FIG. 2 is a sectional view taken along the line II--II with unnecessary parts omitted, FIG. 3 is a side view thereof, and FIG. 4 is a side view of the motorcycle. 5 is a front view, and FIG. 5 is a sectional view taken along line v-■ in FIG. 3. 7...engine, 8...exhaust pipe, 8 turtle...
Constant cross-sectional area part, Bb-... expansion part.

Claims (2)

[Claims] (1) The exhaust pipe, which is located between the front wheels and the rear wheels and is taken out downward from the engine supported by a single frame, is bent backwards, then turned forward, and from there on one plane, A motorcycle exhaust pipe device that is connected to a silencer installed on the lower side of the vehicle body frame after being wrapped approximately once. (2) The exhaust pipe device for a motorcycle according to claim 1, wherein the exhaust pipe includes a constant cross-sectional area portion having a constant length from the engine, and an expanding portion whose cross-sectional area increases from there.