JP2003293764A - Exhaust manifold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust manifold capable of supplying secondary air without providing exhaust resistance. <P>SOLUTION: The exhaust manifold has a double pipe structure having an inner pipe 14 communicating with each exhaust port and an outer shell 16 for covering an inner pipe 14 by overlapping a first shell 18 and a second shell 20 divided in the longitudinal direction of the inner pipe 14. A recess 42 is formed in the first shell 18, a covering member 44 is mounted to cover the recess 42, thereby forming a secondary air supply flow channel 46. The covering member 44 is provided with a supply port 52 at the tip of a communication pipe 50 communicating with the secondary air supply flow channel 46 correspondingly to each exhaust port. The inner pipe 14 is provided with a connecting hole 54 for passing a communication pipe 50 on overlapping the first shell 18 and the second shell 20. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold provided in an exhaust system of a multi-cylinder engine and collecting exhaust gas discharged from each exhaust port and sending it to an exhaust pipe.

[0002]

2. Description of the Related Art Conventionally, since a large amount of unburned components such as CO and HC remain in the exhaust gas when starting the engine,
Secondary air is supplied into the exhaust gas and burned to purify the exhaust gas. For example, as described above, as disclosed in Japanese Patent Laid-Open No. 2000-145447, a recess is formed in the manifold, and the recess is covered with a lid member to form a secondary air supply passage. This secondary air supply channel is
It is proposed that one is open toward the exhaust port and the other is connected to an introduction pipe to which secondary air is supplied.

[0003]

However, in such a conventional one, since the concave portion is formed in the manifold, the concave portion is projected into the exhaust passage, which becomes a resistance of the exhaust gas flowing through the exhaust passage. There was a problem that the output was lowered.

An object of the present invention is to provide an exhaust manifold capable of supplying secondary air without causing exhaust resistance.

[0005]

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 manifold that collects exhaust gas from each exhaust port of a multi-cylinder engine and sends it to an exhaust pipe, it has an inner pipe that communicates with each exhaust port and is divided along the longitudinal direction of the inner pipe. A double pipe structure having an outer shell that overlaps the inner pipe by stacking one shell and a second shell,
A covering member is attached to the first shell to form a secondary air supply passage, and a supply port communicating with the secondary air supply passage is formed corresponding to each exhaust port, and the inner pipe is formed. An exhaust manifold is characterized in that it has a connection port communicating with the supply port.

A recess may be formed in the first shell, and a covering member may be attached to cover the recess to form the secondary air supply passage. Further, the covering member,
The supply port is formed at the tip of the communication pipe part communicating with the secondary air supply flow path, and the communication pipe part is formed on the inner pipe when the first shell and the second shell are superposed on each other. A connection port to be inserted may be formed.

[0007]

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 FIG. 1, reference numeral 1 denotes an exhaust manifold, which is used in a multi-cylinder (four cylinders in this embodiment) engine 100. Engine 10
0 indicates the first to fourth cylinders communicating with the first to fourth cylinders # 1 to # 4
The exhaust ports P1 to P4 are provided.

The exhaust manifold 1 is provided with flanges 2 and 4, and a plurality of mounting holes 6 and 8 for mounting with bolts (not shown) are formed in the flanges 2 and 4. The flanges 2 and 4 are provided with four introduction holes 10 to 13 corresponding to the first to fourth exhaust ports P1 to P4.

The exhaust manifold 1 has a double pipe structure having an inner pipe 14 and an outer shell 16 covering the inner pipe 14. Outer shell 16
Includes a first shell 18 and a second shell 20 that are divided along the longitudinal direction of the inner pipe 14, and the first shell 18 and the second shell 20 are overlapped to cover the inner pipe 14. Has been formed. The second shell 20 is formed with branch pipe portions 22 to 25 that are inserted into the introduction holes 10 to 13 of the flanges 2 and 4, and the branch pipe portions 22 to 25 are inserted into the introduction holes 10 to 13. Has been
It is fixed integrally by welding.

In this embodiment, the inner pipe 14 is composed of three T-shaped pipe portions 26 to 28 and one elbow pipe portion 30, and each branch pipe of the second shell 20. The T-shaped pipe portions 26 to 28 and the elbow-shaped pipe portion 30 are inserted into the portions 22 to 25, and the T-shaped pipe portions 26 to 28 and the elbow-shaped pipe portion 30 are connected to each other to form the inner pipe 14.
An exhaust passage 32 is formed inside.

The peripheral edge of the second shell 20 is bulged outward to form an insertion portion 34, and the insertion portion 34 is formed.
The peripheral edge of the first shell 18 is inserted into and overlapped with each other. A gap 36 is formed between the outer shell 16 and the inner pipe 14. Further, when the first shell 18 and the second shell 20 are overlapped with each other, the connection pipe portion 38 is formed on the downstream side of the exhaust gas, and the flange 4 is formed on the connection pipe portion 38.
0 is attached. The flange 40 is connected to a downstream exhaust pipe (not shown). In addition, the T-shaped tube portion 26
Has one end inserted into the connecting pipe portion 38 via a wire mesh 41.

The first shell 18 includes an inner pipe 14
A recess 42 is formed along the longitudinal direction of the above, and a covering member 44 is attached to the inside of the first shell 18 so as to cover the recess 42. Thereby, the secondary air supply flow path 46 is formed, and the introduction pipe 48 communicating with one end of the secondary air supply flow path 46 is inserted and fixed in the first shell 18.

In the covering member 44, a communicating pipe portion 50 (only a part of which is shown) is formed so as to project toward the inner pipe 14 corresponding to each of the first to fourth exhaust ports P1 to P4. A supply port 52 is formed at the tip of the communication pipe section 50. Corresponding to the communication pipe portion 50, the T-shaped pipe portions 26 to 28 of the inner pipe 14 and the elbow pipe portion 30 are provided with connection ports 54 (only a part of which are shown).

The connecting pipe portion 50 is formed with a length such that its tip can be inserted into the connecting port 54 and an outer diameter.
And the communication pipe portion 50 are formed by connecting the first shell 18 to the second shell 20.
The communication pipe portion 50 is formed so as to be inserted into the connection port 54 when they are overlapped with each other. In addition, the tip of the communication pipe portion 50 is formed to have a length that does not significantly project into the exhaust passage 32 from the connection port 54. When assembling, when the first shell 18 is overlapped with the second shell 20, the communication pipe portion 50
Is inserted into the connection port 54, and the supply port 52 and the connection port 54 are communicated with each other.

Next, the operation of the above-described exhaust manifold of this embodiment will be described. Exhausts from the first to fourth cylinders # 1 to # 4 are discharged from the first to fourth exhaust ports P1 to P1.
It is guided to the exhaust passage 32 via P4, the introduction holes 10 to 13, the T-shaped pipe portions 26 to 28 of the inner pipe 14 and the elbow pipe portion 30. Then, it is sent to the exhaust pipe on the downstream side through the exhaust passage 32.

When the engine 100 is started, air is supplied to the secondary air supply passage 46 through the introduction pipe 48 for a fixed time. Then, from the secondary air supply flow path 46, the exhaust flow path 3 via each communication pipe section 50, the supply port 52, and the connection port 54.
2 is supplied with air. As a result, the combustion of unburned components in the exhaust gas is promoted and the exhaust gas is purified. Further, because of the double-pipe structure, it is possible to prevent the temperature of the exhaust gas from decreasing when the engine is started and to promptly activate the three-way catalyst.

Since the secondary air supply passage 46 is formed in the gap 36 between the inner pipe 14 and the outer shell 16, the provision of the secondary air supply passage 46 does not cause exhaust resistance. Further, when exhaust gas passes through the exhaust flow passage 32, the tip of the communication pipe portion 50 does not protrude into the exhaust flow passage 32, and therefore does not become exhaust resistance.

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.

[0019]

As described above in detail, in the exhaust manifold of the present invention, the secondary air supply passage is formed between the inner pipe and the outer shell. Therefore, even if the secondary air supply passage is provided, the exhaust gas is exhausted. The effect is that the resistance does not increase. Further, the secondary air supply flow path can be easily formed by forming the recess in the first shell and covering the recess with the covering member. Further, when the first shell and the second shell are overlapped with each other, if the communication pipe portion is inserted into the connection port, the assembly becomes easy.

[Brief description of drawings]

FIG. 1 is a front view of an exhaust manifold as an embodiment of the present invention.

FIG. 2 is a bottom view of the exhaust manifold of the present embodiment.

FIG. 3 is a front view showing a cross section of a main part of the exhaust manifold of the present embodiment.

FIG. 4 is an enlarged sectional view taken along line AA of FIG.

5 is a BB enlarged cross-sectional view of FIG.

[Explanation of symbols]

1 ... Exhaust manifold 2, 4 ... Flange 10-13 ... Introduction hole 14 ... Inner pipe 16 ... Outer shell 18 ... 1st shell 20 ... 2nd shell 22 to 25 ... Branch pipe part 26 to 28 ... T-shaped pipe part 30 ... Elbow type pipe section 32 ... Exhaust flow path 36 ... Gap 42 ... Dimple 44 ... Covering member 46 ... Secondary air supply channel 48 ... Introduction pipe 50 ... Communication pipe section 52 ... Supply port 54 ... Connection port

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3G004 BA06 DA02 DA12 DA14 DA22                       FA04 GA02 GA06                 3G091 AA28 AB02 AB16 BA15 BA19                       BA39 CA22 HB01 HB07

Claims (3)

[Claims] 1. An exhaust manifold, which collects exhaust gas from each exhaust port of a multi-cylinder engine and sends the exhaust gas to an exhaust pipe, wherein the exhaust manifold has an inner pipe communicating with each exhaust port and is divided along a longitudinal direction of the inner pipe. A double pipe structure having an outer shell that covers the inner pipe by overlapping the first shell and the second shell that are formed, and forms a secondary air supply flow path by attaching a covering member to the first shell, An exhaust manifold, characterized in that a supply port communicating with the secondary air supply flow path is formed corresponding to each exhaust port, and a connection port communicating with the supply port is formed in the inner pipe. . 2. The exhaust manifold according to claim 1, wherein a recess is formed in the first shell, and a covering member is attached to cover the recess to form the secondary air supply passage. 3. The covering member is formed with the supply port at a tip of a communication pipe portion communicating with the secondary air supply passage, and the inner pipe is provided with the first shell and the second shell. The exhaust manifold according to claim 1 or 2, wherein a connection port into which the communication pipe portion is inserted when the two are overlapped with each other is formed.