JP2892024B2 - Exhaust system for multi-cylinder engine - Google Patents

Description

The present invention relates to an exhaust device for a multi-cylinder engine in a motorcycle.

[Prior Art] FIG. 4 shows an overall side view of a motorcycle. A front fork 4 is rotatably supported on a head pipe 3 constituting a body frame 2 of the motorcycle 1, and a front wheel 5 is provided below the front fork 4. Is provided, and a handle 6 is provided at an upper portion. A rear wheel 9 is supported at the rear end of the main frame 7 extending rearward from the head pipe 3 via a rear arm 8, while an upper portion of the main frame 7 is covered with a tank cover 10. Further, a seat rail 11 is connected to the rear of the main frame 7, and the seat rail 11 is connected to the seat rail 11.
A seat 12 is provided on 11.

An engine 14 is mounted between a down tube 13 extending downward from the front end of the main frame 7 and the main frame 7, and a carburetor 17 and an air cleaner 18 are connected to a cylinder 15 constituting the engine 14, and An exhaust device 19 extends rearward from the front side of the cylinder 15 and below the vehicle body, and is connected to the muffler 22. The front and both sides of the motorcycle 1 are covered with a cowling 21.
A running wind is introduced from a front opening of the radiator 21 to cool the radiator 20.

The engine 14 is a four-cylinder engine. As shown in FIG. 3, each of four exhaust pipes 19a is connected to two exhaust collecting pipes 19b, and further connected to one muffler connecting pipe 19c. doing.

[Problems to be Solved by the Invention] By the way, the exhaust collecting pipe 19b not only avoids exhaust interference of the other cylinders with each other but collectively sends the exhaust of the multi-cylinder to the muffler, and also generates a negative pressure wave generated in the collecting portion. It is designed to positively extract the exhaust of other cylinders to increase the efficiency.

However, the above-described system in which each of the four exhaust pipes 19a is connected to two exhaust collecting pipes 19b and further connected to one muffler connecting pipe 19c is an engine that exerts power at a relatively medium to low speed. It has characteristics, but tends to be unsuitable for high speed. On the other hand, as shown in FIG. 3, four exhaust pipes are provided so as to have engine characteristics that exert power at high speed.
In the system where 19a is connected to one exhaust collecting pipe 19b and further connected to the muffler connecting pipe 19c, no power can be exerted at medium to low speeds due to exhaust interference, but at high speeds, the force is exerted by the effect of the aforementioned negative pressure wave. Can be demonstrated.

An object of the present invention is to solve the above problems,
An object of the present invention is to provide an exhaust system for a multi-cylinder engine capable of efficiently exhibiting engine characteristics from a low speed to a high speed.

Means for Solving the Problems In order to solve the above problems, the present invention provides an exhaust pipe (19a) extending from a multi-cylinder engine and exhaust holes (52a, 52b, 52c, 52d), an exhaust pipe connecting member (52) connected to the exhaust pipe connecting member, a cylindrical exhaust collecting member (53) for collecting exhaust gas, and a muffler connection connecting the exhaust collecting member to a muffler (22). In the exhaust system for a multi-cylinder engine comprising a member (54), the exhaust collecting member (53) is provided with two exhausts inside by a flat partition wall (55) arranged parallel to the axis and deviated from the center of the cross section. One plate valve (57) rotatably supported by the front end of the partition wall is formed between the front end of the partition wall and the rear end of the exhaust pipe connecting member while forming the flow paths (53a, 53b). When the engine speed is equal to or less than a predetermined value, the plate valve (5
7) is configured to be the front of the partition wall (55), and the same number of cylinders that ignite every other exhaust pipe (19a) connected via the exhaust pipe connecting member (52) Collectively, the two exhaust passages (53a, 53b) are circulated. When the engine speed is equal to or more than a predetermined value, the plate valve (53) closes the front end of the exhaust passage (53b) on the side where the partition wall (55) is biased. 57) is rotated and the front part of the partition is opened to exhaust the exhaust gas of all cylinders to the exhaust passage (53a) on the opposite side where the partition is biased.

Note that the numbers added to the above configuration are for comparison with the drawings of the embodiments, and the configuration of the present invention is not limited by this.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment in which the exhaust device according to the present invention is applied to a four-cylinder engine, and FIG. 2 is a sectional view thereof. The exhaust device 51 includes exhaust holes 52a, 52b, and 52 connected to four exhaust pipes 19a (FIG. 3) extending from the multi-cylinder engine.
An exhaust pipe connecting member 52 having c and 52d, a cylindrical exhaust collecting member 53 connected to the exhaust pipe connecting member and collecting exhaust gas, and a muffler connection connecting the exhaust collecting member to the muffler 22 (FIG. 4). And a member 54.

The exhaust collecting member 53 has two exhaust passages 53a and 53b formed therein by a planar partition 55 that is arranged parallel to the axis and deviated from the center of the cross section, and the front end of the partition 55 and the exhaust pipe connecting member. A rotating shaft 56 is attached to the front end of
One plate valve 57 which is rotatably supported by is mounted. The rotating shaft 56 is connected to an output shaft of a motor (not shown) by a wire or the like.

When the engine speed is lower than a predetermined value, the plate valve
57 is configured to be the front of the partition wall 55, and the exhaust pipe connection member
Cylinders that ignite every other exhaust pipe 19a connected via 52 are grouped into two sets of the same number to form two exhaust passages 53a, 53
3b is circulated, and when the engine speed
The plate valve 57 is rotated so as to close the front end of the exhaust flow path 53b on the side where 55 is biased, and the front part of the partition wall 55 is opened, and exhaust of all cylinders is discharged to the opposite exhaust flow path 53a on which the partition wall 55 is biased. It is configured to be distributed.

The operation of the present invention having the above configuration will be described.
If the engine speed is lower than the predetermined value, the plate valve 57
Is set at the position indicated by the solid line in the drawing, and the exhaust of the cylinders that ignite every other from the exhaust holes 52a and 52c flows into the exhaust flow path 53a, and the exhaust of the cylinders that ignite every other of the exhaust holes 52b and 52d. After the exhaust gas flows into the exhaust passage 53b, the exhaust gas is collected into one by the muffler connection member 54. The exhaust gas from each cylinder flows through the exhaust holes 52a, 52b, 52c, and 52d in the order of ignition. When the engine speed becomes equal to or higher than a predetermined value, the valve 57 is switched to the position shown by the dotted line by the motor, so that exhaust of all cylinders from the exhaust holes 52a, 52b, 52c, 52d flows to the exhaust passage 53a. Collected into one.

Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above embodiment, an example in which the present invention is applied to a four-cylinder engine is shown.
The invention may be applied to a multi-cylinder engine such as an eight-cylinder engine.

[Effects of the Invention] As described above, according to the present invention, when the engine speed is equal to or lower than a predetermined value, the plate valve is configured to be located at the front of the partition wall, and the exhaust gas connected via the exhaust pipe connecting member is provided. Since the cylinders that ignite every other pipe are grouped into two sets of the same number and flow through the two exhaust passages, for example, in a four-cylinder engine at the middle and low speeds, the exhaust pipes of the cylinders that ignite every other cylinder Can generate a common pressure wave oscillating in a 360 ° cycle, and the exhaust between the two cylinders also has a 360 ° cycle, so that the overlap period of the intake and exhaust of both cylinders is negative. The pressure wave can be completely matched, and the exhaust can be expelled from the cylinder to increase the charging efficiency.

However, when the engine speed becomes higher than a predetermined value, the pressure waves of the two cylinders interfere with each other and the pressure wave disappears. Therefore, the pressure waves generated by the other sets of exhausts can be combined, the charging efficiency can be increased by the negative pressure waves, and the engine output can be improved from a low speed to a high speed. At this time, since the plate valve rotates so as to close the front end of the exhaust flow path on the side where the partition wall is biased, the rotation angle of the plate valve is reduced, and collision between the exhaust and the plate valve is reduced to reduce exhaust loss. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment in which an exhaust device according to the present invention is applied to a four-cylinder engine, FIG. 2 is a sectional view thereof, and FIG.
FIG. 1 is a perspective view of a conventional exhaust device of a multi-cylinder engine, and FIG. 4 is a side view of a motorcycle for explaining the exhaust device of a conventional multi-cylinder engine. 14 ... multi-cylinder engine, 19a ... exhaust pipe, 22 ... muffler, 52
a, 52b, 52c, 52d ... exhaust holes, 52 ... exhaust pipe connecting members, 53 ...
Exhaust collecting member, 54 ... Muffler connection member, 55 ... Partition wall, 53
a, 53b: exhaust passage, 57: plate valve.

Claims (1)

(57) [Claims] An exhaust pipe extending from a multi-cylinder engine, an exhaust pipe connecting member having an exhaust hole connected to the exhaust pipe,
In an exhaust system for a multi-cylinder engine comprising a cylindrical exhaust collecting member connected to the exhaust pipe connecting member and collecting exhaust gas, and a muffler connecting member connecting the exhaust collecting member to a muffler, the exhaust collecting member has an axial line. Two exhaust passages are formed inside by a planar partition wall which is parallel to and is deviated from the center of the cross section, and a front end of the partition wall is provided between a front end of the partition wall and a rear end of the exhaust pipe connection member. 1 rotatably pivoted to
When the engine speed is equal to or lower than a predetermined value, the plate valve is configured to be a front portion of the partition wall, and every other exhaust pipe connected via an exhaust pipe connection member is provided. The same number of cylinders igniting each other are assembled into two sets of the same number to flow through the two exhaust passages. When the engine speed is equal to or higher than a predetermined value, the plate valve is closed so as to close the front end of the exhaust passage on the side where the partition wall is biased. An exhaust system for a multi-cylinder engine, wherein the exhaust system of a multi-cylinder engine is rotated while opening a front portion of a partition wall, and exhaust gas of all cylinders is caused to flow through an exhaust passage on an opposite side of the partition wall.