JP4092125B2 - Exhaust manifold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust manifold that is provided in an exhaust system of a multi-cylinder engine and collects exhaust exhausted from each exhaust port and sends it to an exhaust pipe.
[0002]
[Prior art]
Conventionally, since many unburned components such as CO and HC remain in the exhaust when starting the engine, secondary air is supplied into the exhaust and burned to purify the exhaust. For example, as described above, as disclosed in Japanese Patent Application 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 flow path. It has been proposed that one of the secondary air supply channels is open toward the exhaust port, and the other is connected to an introduction pipe through which secondary air is supplied.
[0003]
[Problems to be solved by the invention]
However, such a conventional device has a problem in that since the concave portion is formed in the manifold, the concave portion is protruded into the exhaust passage, resulting in resistance of the exhaust gas flowing through the exhaust passage, leading to a decrease in output. It was.
[0004]
An object of the present invention is to provide an exhaust manifold capable of supplying secondary air without causing exhaust resistance.
[0005]
[Means for Solving the Problems]
In order to achieve this problem, the present invention has taken the following measures in order to solve the problem. That is,
In the exhaust manifold that collects exhaust from each exhaust port of a multi-cylinder engine and sends it to the exhaust pipe,
A double pipe structure having an inner pipe communicating with each exhaust port and an outer shell covering the inner pipe by overlapping a first shell and a second shell divided along the longitudinal direction of the inner pipe Prepared,
A cover member is attached to the first shell to form a secondary air supply flow path, a supply port communicating with the secondary air supply flow path corresponding to each exhaust port is formed, and the inner pipe The exhaust manifold is characterized in that a connection port communicating with the supply port is formed.
[0006]
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 channel. In addition, the covering member is formed with the supply port at a tip of a communication pipe portion communicating with the secondary air supply flow path, and the first shell and the second shell are overlapped on the inner pipe. In this case, a connection port into which the communication pipe portion is inserted may be formed.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, reference numeral 1 denotes an exhaust manifold, which is used in a multi-cylinder engine (four cylinders in this embodiment). The engine 100 includes first to fourth exhaust ports P1 to P4 communicating with the first to fourth cylinders # 1 to # 4.
[0008]
The exhaust manifold 1 is provided with flanges 2 and 4, and a plurality of attachment holes 6 and 8 for attachment with bolts (not shown) are formed in the flanges 2 and 4. In the flanges 2 and 4, four introduction holes 10 to 13 corresponding to the first to fourth exhaust ports P1 to P4 are formed.
[0009]
The exhaust manifold 1 is formed in a double pipe structure having an inner pipe 14 and an outer shell 16 covering the inner pipe 14. The 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 covers the inner pipe 14 by overlapping the first shell 18 and the second shell 20. It is formed as follows. The second shell 20 is formed with branch pipe portions 22 to 25 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. And fixed together by welding.
[0010]
In the present embodiment, the inner pipe 14 includes three T-shaped pipe portions 26 to 28 and one elbow-shaped pipe portion 30, and each of the branch pipe portions 22 to 22 of the second shell 20. 25, the T-shaped pipe portions 26 to 28 and the elbow-shaped pipe portion 30 are inserted, and the T-shaped pipe portions 26 to 28 and the elbow-shaped pipe portion 30 are connected to each other so that the exhaust gas flows into the inner pipe 14. A path 32 is formed.
[0011]
The peripheral edge of the second shell 20 is expanded outward to form an insertion portion 34, and the peripheral edge of the first shell 18 is inserted into and overlapped with the insertion portion 34. 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, a connecting pipe portion 38 is formed on the downstream side of the exhaust, and a flange 40 is attached to the connecting pipe portion 38. The flange 40 is connected to a downstream exhaust pipe (not shown). Further, one end of the T-shaped pipe part 26 is inserted into the connection pipe part 38 via the wire mesh 41.
[0012]
A recess 42 is formed in the first shell 18 along the longitudinal direction of the inner pipe 14, and a covering member 44 is attached to the inside of the first shell 18 so as to cover the recess 42. As a result, a secondary air supply channel 46 is formed, and an introduction pipe 48 communicating with one end of the secondary air supply channel 46 is inserted into the first shell 18 and fixed.
[0013]
The covering member 44 is formed with a communication pipe portion 50 (only a part of which is shown) protruding toward the inner pipe 14 corresponding to the first to fourth exhaust ports P1 to P4. A supply port 52 is formed at the distal end of the communication pipe unit 50. Corresponding to the communication pipe portion 50, connection ports 54 (only a part of which are shown) are formed in the T-shaped pipe portions 26 to 28 and the elbow-type pipe portion 30 of the inner pipe 14.
[0014]
The communication pipe portion 50 is formed with a length and an outer diameter at which the tip can be inserted into the connection port 54, and the connection port 54 and the communication pipe portion 50 are obtained by overlapping the first shell 18 on the second shell 20. At this time, the communication pipe portion 50 is formed so as to be inserted into the connection port 54. Further, the length of the communication pipe portion 50 is formed so as not to protrude greatly into the exhaust flow path 32 from the connection port 54. At the time of assembly, 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.
[0015]
Next, the operation of the exhaust manifold of the present embodiment described above will be described.
Exhaust gas from the first to fourth cylinders # 1 to # 4 is supplied to the first to fourth exhaust ports P1 to P4, the introduction holes 10 to 13, the T-shaped pipe portions 26 to 28 of the inner pipe 14, and the elbow type pipe portions. 30 to the exhaust passage 32. Then, it is sent to the exhaust pipe on the downstream side through the exhaust passage 32.
[0016]
When the engine 100 is started, air is supplied to the secondary air supply flow path 46 through the introduction pipe 48 for a fixed time. Then, air is supplied from the secondary air supply flow path 46 to the exhaust flow path 32 through each communication pipe portion 50, the supply port 52, and the connection port 54. Thereby, the combustion of the unburned components in the exhaust is promoted, and the exhaust is purified. Moreover, since it has a double-pipe structure, it is possible to prevent the temperature of the exhaust gas from decreasing when the engine is started and to activate the three-way catalyst quickly.
[0017]
Since the secondary air supply flow path 46 is formed in the gap 36 between the inner pipe 14 and the outer shell 16, even if the secondary air supply flow path 46 is provided, there is no exhaust resistance. Further, when the exhaust gas passes through the exhaust flow channel 32, the tip of the communication pipe portion 50 does not protrude into the exhaust flow channel 32, so that there is no exhaust resistance.
[0018]
The present invention is not limited to such embodiments as described above, and can be implemented in various modes without departing from the gist of the present invention.
[0019]
【The invention's effect】
As described above in detail, in the exhaust manifold of the present invention, the secondary air supply flow path is formed between the inner pipe and the outer shell, so that even if the secondary air supply flow path is provided, the exhaust resistance increases. There is an effect that there is no. Moreover, a secondary air supply flow path can be easily formed by forming a depression in the first shell and covering the depression with a covering member. Furthermore, when the first shell and the second shell are overlapped with each other, assembly is facilitated by inserting the communication pipe portion into the connection port.
[Brief description of the drawings]
FIG. 1 is a front view of an exhaust manifold as one 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 in cross section the main part of the exhaust manifold of the present embodiment.
4 is an AA enlarged sectional view of FIG. 1; FIG.
5 is an enlarged cross-sectional view taken along the line BB in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Exhaust manifold 2, 4 ... Flange 10-13 ... Introduction hole 14 ... Inner pipe 16 ... Outer shell 18 ... 1st shell 20 ... 2nd shell 22-25 ... Branch pipe part 26-28 ... T-shaped pipe part 30 ... Elbow type pipe section 32 ... exhaust passage 36 ... gap 42 ... depression 44 ... covering member 46 ... secondary air supply passage 48 ... introduction pipe 50 ... communication pipe section 52 ... supply port 54 ... connection port

Claims (3)

In the exhaust manifold that collects exhaust from each exhaust port of a multi-cylinder engine and sends it to the exhaust pipe,
A double pipe structure having an inner pipe communicating with each exhaust port and an outer shell covering the inner pipe by overlapping a first shell and a second shell divided along the longitudinal direction of the inner pipe Prepared,
A cover member is attached to the first shell to form a secondary air supply flow path, a supply port communicating with the secondary air supply flow path corresponding to each exhaust port is formed, and the inner pipe The exhaust manifold is characterized in that a connection port communicating with the supply port is formed. 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 flow path. In the covering member, the supply port is formed at the tip of a communication pipe portion communicating with the secondary air supply flow path, and the first shell and the second shell are overlapped with the inner pipe. The exhaust manifold according to claim 1 or 2, wherein a connection port into which the communication pipe portion is inserted is formed in the exhaust manifold.

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