JP2003206740A - Exhaust device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust device for an internal combustion engine capable of generating an eddy current and improving exhaust efficiency with a simple constitution. <P>SOLUTION: Branch pipes 2a to 2d installed at every cylinder of a four-cycle four-cylinder internal combustion engine are gathered to connect with an exhaust pipe 4. The side end of the exhaust pipe 4 of each branch pipe 2a to 2d is gathered around a gathering center 11 and provided with spiral walls 14a to 14d generating the eddy current to the exhaust flowing in the exhaust pipe 4 every branch pipe 2a to 2d. The spiral walls 14a to 14d are formed by twisting partition boards 12a to 12d partitioning each branch pipe 2a to 2d. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system for an internal combustion engine in which branch pipes provided for each cylinder of the internal combustion engine are assembled and connected to an exhaust pipe.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine, for example, a 4-cycle 4-cylinder internal combustion engine, the combustion order of each cylinder is usually
In the order of the first, third, fourth, and second cylinders, the crank angle is 18
It is performed every 0 degrees. At that time, the exhaust process is 18 times for each cylinder.
Since it is 0 degrees or more, the exhaust valve is always open in two cylinders out of four cylinders.

At the same time, when the exhaust valves of the two cylinders are open, the high pressure exhaust at the beginning of the exhaust process tends to flow into the low pressure cylinder at the end of the exhaust process. When the high-pressure side exhaust gas flows into the low-pressure side cylinder, scavenging and intake of the low-pressure side cylinder are obstructed, resulting in a decrease in output and deterioration of fuel efficiency. In order to prevent such exhaust interference, for example, as disclosed in Japanese Utility Model Laid-Open No. 5-21124, a downstream side of an extended flow path connecting the branch pipes of the first cylinder and the fourth cylinder, and 2 cylinder and 3rd
It has been proposed that the center of each opening on the downstream side, which is an extension of a flow path connecting the branch pipes of the cylinder, is located on the opposite side from the center position of the exhaust pipe by the same position. As a result, the exhaust does not interfere with each other, and a swirl flow is generated to realize high output and low fuel consumption.

[0004]

However, in such a conventional one, the branch pipes of the first cylinder and the fourth cylinder and the branch pipes of the second cylinder and the third cylinder are connected to each other, and
One flow path must be formed, and further, the downstream side of both flow paths must be formed so that the centers of the openings of both flow paths are displaced by a predetermined distance, which is a problem in that the formation is complicated.

An object of the present invention is to provide an exhaust system for an internal combustion engine which can generate a vortex with a simple structure and improve exhaust efficiency.

[0006]

In order to achieve the above object, the present invention takes the following means in order to solve the object. That is, in an exhaust system for an internal combustion engine in which branch pipes provided for each cylinder of the internal combustion engine are collected and connected to an exhaust pipe,
The exhaust pipe side ends of the branch pipes are gathered around a gathering center, and a spiral wall for causing a swirl in the exhaust gas flowing into the exhaust pipes is provided for each of the branch pipes. It is an exhaust system for an internal combustion engine.

Further, the spiral wall may be formed by twisting a partition plate for partitioning each of the branch pipes. Further, the ends of the branch pipes on the exhaust pipe side may be opened on the same plane. Further, the branch pipes in which the exhaust sequence from each cylinder of the internal combustion engine is continuous may be adjacent to each other, and the branch pipes may be gathered around the gathering center. The internal combustion engine preferably has four cycles and four cylinders. Further, the spiral wall may cause the vortex flow around the gathering center.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. As shown in FIGS. 1 and 3, 1
Is a 4-cycle 4-cylinder internal combustion engine.
First to fourth branch pipes 2a to 2d are connected to each of the fourth cylinders. In each cylinder, exhaust is performed in the order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder.

The first to fourth branch pipes 2a to 2d are assembled and connected to the exhaust pipe 4, and the exhaust gas from the exhaust pipe 4 is further discharged through the catalytic converter 6, the sub muffler 8 and the main muffler 10. It is configured to be. The catalytic converter 6 is provided with a three-way catalyst body (not shown), and the three-way catalyst body is a well-known one in which a catalyst such as a noble metal is carried on a honeycomb-shaped ceramic carrier. This three-way catalyst body is usually activated at about 300 ° C. or higher.

In the present embodiment, the four first to fourth branch pipes 2a to 2d described above are formed so that their respective lengths are equal, as shown in FIG. And
The exhaust pipe 4 side ends are gathered in one place and connected to one exhaust pipe 4. Four first to fourth branch pipes 2a to 2
The ends of d on the exhaust pipe 4 side are gathered around the gathering center 11, and the first to fourth branch pipes 2a to 2d having a circular cross section are
Each end is formed into a circular 1/4 fan-shaped cross section,
They are assembled so as to form one large circle centered on the assembly center 11.

Further, the open ends of the first to fourth branch pipes 2a to 2d on the exhaust pipe 4 side are aligned so as to open on the same plane. In the present embodiment, as shown in FIG. 3, when the openings of the first to fourth branch pipes 2a to 2d are viewed from the exhaust pipe 4 side, the openings are arranged adjacent to each other in the exhaust order.
The cylinders, the third cylinder, the fourth cylinder, and the second cylinder are arranged clockwise in this order.

First branch pipe 2a and second branch pipe 2b
The first partition plate 12a is provided so as to be sandwiched between and.
The first partition plate 12a projects toward the exhaust pipe 4 side from the first branch pipe 2a and the second branch pipe 2b. Similarly, a third partition plate 12c is provided between the first branch pipe 2a and the third branch pipe 2c, and a fourth partition plate 12d is provided between the third branch pipe 2c and the fourth branch pipe 2d. A second partition plate 12b is provided between the second branch pipe 2b and the fourth branch pipe 2d. These first to fourth partition plates 1
2a to 12d partition the fan-shaped openings at the ends of the first to fourth branch pipes 2a to 2d on the exhaust pipe 4 side, and are integrally formed in a cross shape. The first to fourth partition plates 12a to 12d may not be integrated, but may be independently provided. Alternatively, a part of the open ends of the first to fourth branch pipes 2a to 2d may be cut out so that the first to fourth partition plates 12a to 12d are also used.

The other ends of the first to fourth partition plates 12a to 12d protruding into the exhaust pipe 4 are twisted on the outer peripheral side, as shown in FIG. First to fourth partition plates 12a to 1
The outer peripheral side of 2d is greatly twisted, and the twist is reduced toward the center 11 of the assembly.

Taking the case of the first partition plate 12a as an example, the outer peripheral end of the first partition plate 12a is twisted toward the first branch pipe 2a so as to cover a part of the outlet of the first branch pipe 2a. Is formed in. Further, the twist amount of the first partition plate 12a gradually decreases toward the collecting center 11, and the twist amount gradually decreases toward the outlet of the first branch pipe 2a even in the axial direction of the first branch pipe 2a. Is formed. The same applies to the other second to fourth branch pipes 2b to 2d and the second to fourth partition plates 12b to 12d.

The first to fourth partition plates 12a to 12d are
While being inserted into the exhaust pipe 4, the tips of the first to fourth branch pipes 2a to 2d are also inserted into and connected to the exhaust pipe 4. With the first to fourth partition plates 12a to 12d, the first
~ Fourth spiral walls 14a to 14d are formed,
The exhaust gas from the first to fourth branch pipes 2a to 2d is the exhaust pipe 4
When flowing into the inside, the exhaust gas is discharged from the first to fourth spiral walls 14
It is configured to hit a to 14d.

Next, the operation of the exhaust system for an internal combustion engine of this embodiment described above will be explained. With the operation of the internal combustion engine 1, exhaust is sequentially performed from the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder. First, the exhaust from the first cylinder is
It flows into the exhaust pipe 4 through the branch pipe 2a.

The exhaust gas passing through the first branch pipe 2a is
It hits the first spiral wall 14a of the partition plate 12a and flows along the first spiral wall 14a. Therefore, a rotational force in the circumferential direction is applied to the exhaust gas, and a swirl flow of the exhaust gas is generated around the collecting center 11. Similarly, the exhaust gas from the third cylinder also flows into the exhaust pipe 4 through the third branch pipe 2c. At that time, the exhaust gas strikes the third spiral wall 14c and flows along the third spiral wall 14c. Therefore, a rotational force in the circumferential direction is applied to the exhaust gas, and a swirl flow of the exhaust gas is generated around the collecting center 11. The same applies to the exhaust from the fourth cylinder and the second cylinder, a rotational force in the circumferential direction is applied to the exhaust, and a swirl of the exhaust is generated around the collecting center 11.

The final stage of exhaust from the first cylinder and the initial stage of exhaust from the third cylinder overlap. At that time, although the exhaust pressure from the first cylinder is low and the exhaust pressure from the third cylinder is high, the pressure is low at the assembly center 11 due to the generation of the vortex,
Even if the exhaust pressure of the third cylinder is high, the exhaust gas from the first cylinder also flows into the exhaust pipe 4. Further, the exhaust gas from the third cylinder can be prevented from flowing into the first branch pipe 2a, and the exhaust efficiency can be improved, so that the output can be improved.

Moreover, the first to fourth branch pipes 2a to 2d
Are assembled around the assembly center 11, and the first to fourth spiral walls 14a to 1d are provided for each of the first to fourth branch pipes 2a to 2d.
4d is provided to generate a vortex flow. The 1st-4th spiral walls 14a-14d are the 1st-4th partition plates 12a-12.
Since it can be formed by twisting d, the exhaust efficiency can be improved with a simple structure. Further, the generation of the vortex makes it possible to make the exhaust in the exhaust pipe 4 uniform, so that the exhaust uniformly hits the oxygen sensor, the three-way catalyst, and the like.

The present invention is not limited to such an embodiment as described above, and can be carried out in various modes without departing from the scope of the present invention.

[0021]

As described above in detail, in the exhaust system for an internal combustion engine of the present invention, the branch pipes are gathered around the gathering center and the exhaust is abutted against the spiral wall to generate a swirl flow. The structure has the effect of improving exhaust efficiency. Also, due to the eddy current,
The exhaust gas in the exhaust pipe can be made uniform, and the oxygen sensor, the three-way catalyst, etc. can be evenly hit. Further, by forming the spiral wall with the partition plate, the structure can be further simplified.

[Brief description of drawings]

FIG. 1 is a front view showing a branch pipe and an exhaust pipe of an exhaust system for an internal combustion engine as an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a partition plate of the present embodiment.

FIG. 3 is an explanatory diagram of an adjacent arrangement of branch pipes of the present embodiment.

FIG. 4 is a block diagram showing an exhaust system of the internal combustion engine of the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2a-2d ... 1st-4th branch pipe 4 ... Exhaust pipe 6 ... Catalytic converter 8 ... Sub muffler 10 ... Main muffler 11 ... Collecting center 12a-12d ... 1st-4th partition plate 14a-14d ... 1st-4th spiral wall

Claims (6)

[Claims] 1. An exhaust system for an internal combustion engine in which branch pipes provided for each cylinder of an internal combustion engine are assembled and connected to an exhaust pipe, wherein the exhaust pipe side ends of the branch pipes are assembled around a collection center. An exhaust device for an internal combustion engine, characterized in that a spiral wall for causing a swirl in the exhaust gas flowing into the exhaust pipe is provided for each of the branch pipes. 2. The exhaust system for an internal combustion engine according to claim 1, wherein the spiral wall is formed by twisting a partition plate for partitioning each of the branch pipes. 3. The exhaust system for an internal combustion engine according to claim 1, wherein the ends of the branch pipes on the exhaust pipe side are opened on the same plane. 4. The branch pipes in which the exhaust sequences from the cylinders of the internal combustion engine are consecutive are adjacent to each other, and the branch pipes are gathered around the gathering center. Item 3. An exhaust system for an internal combustion engine according to item 3. 5. The exhaust system for an internal combustion engine according to claim 1, wherein the internal combustion engine has four cycles and four cylinders. 6. The exhaust system for an internal combustion engine according to claim 1, wherein the spiral wall causes the vortex flow around the gathering center.