JPS6241925A - Exhaust device for four cylinder engine - 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 [Technical Field of the Invention] The present invention relates to an exhaust system for a four-cylinder engine that improves engine output.

[Technical background and problems of the invention]

In an engine, an exhaust pipe is connected to the engine's exhaust hole, and a muffler is connected to the rear end of the exhaust pipe.The muffler muffles noise and releases exhaust gas into the atmosphere. If the length of the exhaust pipe is set to a length that makes effective use of the pulsating waves of the exhaust gas,
The pulsating waves can create negative pressure near the engine exhaust hole, reducing exhaust gas discharge resistance.
It is known that the power of the engine can be increased. However, the wavelength of the pulsating waves of exhaust gas changes depending on the rotation speed, and it is not possible to improve the output over the entire rotation range. Therefore, in general, the exhaust pipe is set so that high output can be obtained at high speed and high output. , pulsation effect cannot be obtained in low speed range. Further, even if the exhaust pipe is provided with long and short lengths and is switched depending on the engine rotation, the layout is difficult in the case of a motorcycle engine where the exhaust system is exposed.

[Purpose of the invention]

In view of this, this invention provides two exhaust passages, long and short, which are selected by a switching valve according to the engine rotation, thereby providing high output in both the low speed and high speed ranges, and making it suitable for engines mounted on motorcycles. The purpose is to obtain a compact usable exhaust system for a four-cylinder engine.

[Structure of the invention]

Embodiments of the present invention shown in the drawings will be described below.

Long pipes are placed on both the left and right sides of the short collecting pipe, with a 1° detour around the short collecting pipe. In the figure, there are two long pipes on each side, but they may be combined into one on each side.

The short collecting pipe/ and the long pipes on both sides are joined at the front and back, and at the front end, four exhaust pipes 3 connected to each exhaust hole of a four-cylinder engine are connected to the left and right. A muff flag is connected to the merged rear end. A swing type switching valve 5 is provided at the front end merging portion of the short collecting pipe and the left and right long pipes. The left switching valve is swung by a servo motor or the like operated by a governor switch that detects the engine speed, and is switched to allow the long pipe to pass in the low speed range and to pass the collecting short pipe in the high speed range.

Therefore, the long pipes are set to a length that can effectively utilize the pulsating waves of the exhaust gas that pulsate in the low speed range, improving low speed output, and the collecting short pipes are set to a length that can effectively utilize the pulsating waves of the exhaust gas that pulsate in the low speed range. It is set to a length that can be used effectively, improving high-speed output,
Each of them is selectively used according to the rotational speed by switching the switching valve S, so that the output can be increased at both high and low speeds. and,
Long pipes are placed on both sides of the short collecting pipe, so in cases such as motorcycles, it can be placed inconspicuously under the vehicle body, and it is wide overall and thin in the vertical direction, making it convenient. Can be installed well.

〔Effect of the invention〕

As explained above, the present invention arranges the long pipes by detouring them to the left and right sides of the short collecting pipe, merging the short collecting pipes and the long pipes at the front and back, and connecting the four exhaust pipes to the front end. A mat is connected to the rear end, and a switching valve is installed at the front end confluence of the short collecting pipe and the long pipe.The switching valve connects the exhaust pipe to the long pipe side in low speed ranges and to the short collecting pipe side in high speed ranges. Since the engine speed is changed according to the engine rotation, the resistance of the exhaust gas can be reduced by the pulsation effect that matches the rotation at both high and low speeds, and the output can be improved. and,
By placing long pipes on both sides of the collecting short pipe, we have made it possible to make it wider and thinner, so when it comes to motorcycles, etc.
It can be placed inconspicuously on the underside of the vehicle, and can be conveniently installed without reducing road clearance.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 7 being a longitudinal sectional plan view, FIG. 2 being a perspective view of the switching valve, and FIG. 3 being a cross-sectional view. C...Collection short pipe, C...Long pipe, 3...Exhaust pipe, y...
··scarf,! ...Switching valve.

Claims (1)

[Claims] Long pipes are placed around the left and right sides of the collecting short pipes, the collecting short pipes and long pipes are merged at the front and back, the four exhaust pipes are connected to the front end, the muffler is connected to the rear end, and the collecting short pipes are connected to the rear end. A switching valve is provided at the front end confluence of the pipe and the long pipe, and the switching valve is switched according to the engine rotation so that the exhaust pipe and the long pipe side communicate with each other in a low speed range, and the short pipe side communicates with the collecting pipe in a high speed range. An exhaust system for a four-cylinder engine featuring