JP2001140640A - Exhaust device - Google Patents

Abstract

(57) [Problem] To provide an exhaust device capable of improving exhaust efficiency and improving output of an internal combustion engine while having a simple structure. SOLUTION: A first middle pipe portion 32 through which exhaust gas discharged from some cylinders of the multi-cylinder engine flows, and a pipe body through which exhaust gas discharged from a cylinder different from some of the cylinders flow. The first middle pipe portion 32 is connected to the first middle pipe portion 32 and is joined to the second middle pipe portion 33 of the first middle pipe portion 32 to open and close the first middle pipe portion 32. First lid 41
And a coil spring 43 for urging the first lid in the closing direction.
And a second lid 42 that is disposed at a junction of the second middle pipe 33 with the first middle pipe 32 and opens and closes the second middle pipe 33, and biases the second lid 42 in a closing direction. And a coil spring 44.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system used for an exhaust system of a multi-cylinder engine.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Utility Model Laid-Open Publication No. 4-137223, an exhaust system for a four-cycle multi-cylinder engine, which is composed of a plurality of exhaust pipes connected to the engine. It is known that a groove is provided in a partition wall at a position, a partition plate is inserted into the groove, and the partition plate can be taken in and out. This exhaust system changes the substantial length and outlet area of each exhaust pipe according to the engine speed by taking in and out the partition plate, and makes the pulsation in the exhaust pipe work effectively over almost the entire engine speed range. It is intended to improve the engine output by obtaining the effect of exhaust inertia.

[0003]

However, such an exhaust system has the following problems.
That is, a mechanism for moving the partition plate in and out of the gathering position of the exhaust pipe is required. This mechanism involves a driving device such as a motor for moving the partition plate, and is complicated. In addition, in order to properly move the partition plate in and out according to the exhaust flow rate, a sensor for detecting the exhaust flow rate is required, and a great deal of cost is required for manufacturing the apparatus.

Accordingly, the present invention has been made to solve such a problem, and provides an exhaust system capable of improving exhaust efficiency and improving output of an internal combustion engine while having a simple structure. The purpose is to:

[0005]

That is, an exhaust system according to the present invention includes a first pipe body through which exhaust gas discharged from some cylinders of a multi-cylinder engine flows, and a cylinder different from some cylinders. A second pipe body, which is a pipe body through which the exhaust gas to be discharged is circulated and is joined and connected to the first pipe body, and the first pipe body is disposed at a junction of the second pipe body of the first pipe body. First opening / closing means for opening / closing, first urging means for urging the first opening / closing means in a closing direction, and opening / closing of the second pipe disposed at a junction of the second pipe and the first pipe. The apparatus includes a second opening / closing means and a second urging means for urging the second opening / closing means in a closing direction.

According to the present invention, when the flow rate of the exhaust gas in the first pipe body and the second pipe body is small, the force of the exhaust gas pressing the first opening / closing means and the second opening / closing means is small. The degree of opening of the first opening / closing means and the second opening / closing means is reduced by the urging of the urging means and the second urging means. Therefore,
The opening area of the first pipe and the second pipe is reduced, the flow velocity of the exhaust gas alternately discharged from the first pipe and the second pipe is increased, and the exhaust gas discharge efficiency can be improved. .

On the other hand, when the exhaust gas flow in the first pipe and the second pipe is large, the force of the exhaust gas pressing the first opening / closing means and the second opening / closing means becomes large. The opening degree of the first opening / closing means and the second opening / closing means is increased against the urging of the urging means. Therefore, the opening area of the first tube and the second tube is increased, and a large amount of exhaust gas can be smoothly discharged from the first tube and the second tube.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to the accompanying drawings. In each of the drawings, the same elements are denoted by the same reference numerals, and redundant description will be omitted. Also, the dimensional ratios in the drawings do not always match those described.

FIG. 1 shows an exhaust device according to this embodiment.

As shown in FIG. 1, an exhaust system 1 according to this embodiment improves the exhaust efficiency of an engine 2, and is used, for example, in a dual exhaust type exhaust system. The engine 2 has multiple cylinders. For example, the exhaust system 1 is installed in an exhaust system of a four-cycle four-cylinder engine.

An exhaust manifold 3 is connected to the engine 2. The exhaust manifold 3 is a manifold that collectively sends exhaust gas sequentially discharged from each cylinder of the engine 2 to an exhaust pipe and a muffler, and is a pipe connected to an exhaust port of each cylinder. It has two branch sections 31.

[0012] Of the four branch pipe sections 31, two of them merge into the first middle pipe section 32, and the other two branch pipe sections 31 into the second middle pipe section 3.
Merges with 3. First middle pipe part 32 and second middle pipe part 33
Extend adjacently and in parallel, for example, the first middle tube portion 3
A .theta. Pipe having a .theta.-shaped cross section in which both the second and second middle pipe portions 33 are combined is used. First middle pipe part 32 and second middle pipe part 33
Are joined at a downstream end portion thereof, and are connected to the main pipe portion 34 via a connecting pipe 51.

[0013] The first middle tube portion 32 which merges with the second middle tube portion 33
Is provided with a first lid 41 at the end portion. A second lid 42 is provided at the end of the second middle pipe 33 that merges with the first middle pipe 32.

FIG. 2 is an enlarged view of the exhaust device.

As shown in FIG. 2, the first lid 41 is an opening / closing means for opening and closing the end of the first middle pipe portion 32,
1 is rotatably mounted. The second lid 42 is
Opening / closing means for opening / closing the end of the second middle tube portion 33, which is rotatably attached to the connecting tube 51 similarly to the first lid 41.

The first lid 41 and the second lid 42 are opened and closed around a partition 35 that separates the first middle pipe 32 and the second middle pipe 33, and are gradually opened from the vicinity of the partition 35. It is arranged in.

A coil spring 43 is attached to the first lid 41. The coil spring 43 is a biasing unit that biases the first lid 41 in the closing direction, and is disposed between the back of the first lid 41 and the inner wall of the connection pipe 51. on the other hand,
A coil spring 44 is attached to the second lid 42. The coil spring 44 is an urging unit that urges the second lid 42 in the closing direction, and includes a back portion of the second lid 42 and the connecting pipe 5.
1 between the inner wall.

A connecting pipe 51 is attached to a terminal position of the first middle pipe part 32 and the second middle pipe part 33. Connecting pipe 5
1 is a first middle pipe part 32, a second middle pipe part 33, and a main pipe part 34.
And a tube body having an inner diameter larger than the end outer shape of the first middle pipe part 32, the second middle pipe part 33, and the end outer shape of the main pipe part 34.

The sectional shape of the first middle tube portion 32 and the second middle tube portion 33 is the cross section taken along the line II in FIG.
2 and the second middle tube portion 33 are combined into a circular shape,
The partition 35 has a shape crossing the center thereof. Also, the cross-sectional shapes of the end portions of the first middle tube portion 32 and the second middle tube portion 33 are as follows:
The cross section taken along the line II-II in FIG. 2 has a substantially square shape in a state where both are combined, and has a shape in which the partition wall 35 crosses the center position.

The cross-sectional shape of the main pipe section 34 is shown in FIG.
-III is circular in cross section. In addition, main section 3
The cross-sectional shape of the end portion 4 is substantially square in the cross section taken along line IV-IV in FIG.

As described above, by making the cross-sectional shapes of the ends of the first middle pipe portion 32 and the second middle pipe portion 33 substantially square, the first lid 41 and the second lid 42 are connected to the inside of the connecting pipe 51. Thus, it is possible to surely bring the full open state. For example, if the cross-sectional shape of the end part of the first middle pipe part 32 and the second middle pipe part 33 is circular, the shapes of the first lid 41 and the second lid 42 are semicircular, and these first lids are formed. When the first lid 41 and the second lid 42 are fully opened, the side edges of the first lid 41 and the second lid 42 are likely to come into contact with the connecting pipe 51, and the connecting pipe 51 must be enlarged. is there. Therefore, the first middle pipe 3
By making the cross-sectional shapes of the end portions of the second and second middle tube portions 33 substantially square, the first lid 41 and the second lid 42 can be made substantially rectangular, thereby avoiding the above-described problems. Can be.

Next, the operation of the exhaust device according to this embodiment will be described.

In FIG. 1, when the engine 2 is driven,
Exhaust gas is sequentially discharged from the exhaust port of each cylinder. This exhaust gas flows into one of the first middle pipe part 32 and the second middle pipe part 33 through the branch pipe part 31. Since the exhaust timing of the exhaust gas of each cylinder is different, the exhaust gas flows alternately through the first middle pipe part 32 and the second middle pipe part 33.

As shown in FIG. 2, when the number of revolutions of the engine 2 is low and the amount of exhaust gas discharged from the exhaust port of each cylinder of the engine 2 is small, Also, the exhaust flow rate in the second middle pipe portion 33 is small, and the force with which the exhaust gas presses the first lid 41 and the second lid 42 is also small. For this reason, the degree of opening of the first lid 41 and the second lid 42 is reduced by the urging of the coil springs 43 and 44.

Therefore, the first middle tube portion 32 and the second middle tube portion 3
3 has a smaller opening area, and the exhaust gas discharged from the first middle pipe part 32 or the second middle pipe part 33 is accelerated. As a result, the pressure near the outlets of the first middle pipe part 32 and the second middle pipe part 33 decreases, and the exhaust gas discharged from the first middle pipe part 32 and the second middle pipe part 33 alternately is discharged. Efficiency can be improved.

On the other hand, as shown in FIG. 3, when the rotation speed of the engine 2 is high and the amount of exhaust gas discharged from the exhaust port of each cylinder of the engine 2 is large, the first middle pipe section 3
The flow rate of exhaust gas in the second 2 and the second middle pipe portion 33 increases, and the force with which the exhaust gas presses the first lid 41 and the second lid 42 also increases. For this reason, the opening degree of the first lid 41 and the second lid 42 is increased against the bias of the coil springs 43 and 44.

Therefore, the first middle tube portion 32 and the second middle tube portion 3
3 has a large opening area, so that a large amount of exhaust gas can be smoothly discharged from the first middle pipe part 32 and the second middle pipe part 33. Also in this case, the exhaust gas discharged from the first middle pipe part 32 or the second middle pipe part 33 is accelerated, and the pressure near the outlets of the first middle pipe part 32 and the second middle pipe part 33 decreases. I do. Thereby, the discharge efficiency of the exhaust gas discharged alternately from the first middle pipe part 32 and the second middle pipe part 33 can be improved.

As described above, according to the exhaust system 1 according to the present embodiment, the first middle pipe section 32 and the second middle pipe section 33 are controlled according to the flow rate of the exhaust gas flowing through the first middle pipe section 32 and the second middle pipe section 33. Since the opening area of the second middle pipe portion 33 is appropriately changed, in both cases where the flow rate of the exhaust gas is small and large,
The flow velocity of the exhaust gas at the junction of the first middle pipe part 32 and the second middle pipe part 33 can be increased, and the exhaust efficiency can be improved due to the pressure drop at the junction.

Further, the back pressure is reduced by the improvement of the exhaust efficiency, and the engine output can be improved.

In this embodiment, the exhaust device 1 used in the exhaust system of the four-cylinder engine 2 has been described. However, the exhaust device according to the present invention is not limited to such an exhaust device. It may be used in an exhaust system of a multi-cylinder engine other than four cylinders such as a cylinder engine or an eight-cylinder engine.

In the present embodiment, the exhaust device 1
Is applied to the junction of the first middle pipes 32, 33, but the exhaust device according to the present invention is not limited to such a case, and is applied to the junction of the branch pipes 31, 31. May be performed. Even in this case,
The same operation and effect as those of the exhaust device 1 described above can be obtained.

In the present embodiment, the first lid 4
Coil springs 43 as urging means for the first and second lids 42;
Although the exhaust device 44 is used, the exhaust device according to the present invention is not limited to such a device, and may use a leaf spring or the like as the urging means.

In the present embodiment, the first lid 4
Although the exhaust device 1 in which the first and second lids 42 are attached to the connection pipe 51 has been described, the exhaust device according to the present invention is not limited to such an exhaust device.
May be attached to the first middle tube portion 32 and the second lid 42 is attached to the second middle tube portion 33.

Further, in the present embodiment, the first lid 4
Although the exhaust device 1 in which the first and second lids 42 have a flat plate shape has been described, the exhaust device according to the present invention is not limited to such an exhaust device, and the first lid 41 and the second lid 41 are not limited thereto. The body 42 may be formed in a curved shape to smooth the flow of exhaust gas. In this case, the ventilation resistance of the exhaust system is reduced, and the back pressure can be reduced.

[0035]

As described above, according to the present invention, the opening areas of the first pipe and the second pipe are appropriately adjusted according to the flow rate of the exhaust gas flowing through the first pipe and the second pipe. Therefore, in both cases where the flow rate of the exhaust gas is small and large, the flow rate of the exhaust gas at the junction of the first pipe and the second pipe can be increased. In addition, the exhaust efficiency can be improved.

Further, the back pressure is reduced by the improvement of the exhaust efficiency, and the engine output can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an exhaust device according to an embodiment.

FIG. 2 is an enlarged view of the exhaust device of FIG.

FIG. 3 is an explanatory diagram of an operation of the exhaust device according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Exhaust device, 2 ... Engine (multi-cylinder engine), 32
... First middle pipe part (first pipe), 33 ... second middle pipe part (second pipe), 41 ... first lid (first opening / closing means), 42 ... second lid (second opening / closing) Means), 43 ... Coil spring (first urging means), 44 ... Coil spring (second urging means).

Claims (1)

[Claims] A first pipe through which exhaust gas discharged from some of the cylinders of the multi-cylinder engine flows, and a pipe through which exhaust gas discharged from a cylinder different from the one of the plurality of cylinders flows. A second pipe joined and connected to the first pipe, and a first opening / closing means disposed at a junction of the first pipe and the second pipe to open and close the first pipe, First urging means for urging the first opening / closing means in a closing direction, and second opening / closing means disposed at a junction of the second pipe with the first pipe to open and close the second pipe. An exhaust device comprising: a second biasing unit that biases the second opening / closing unit in a closing direction.