JP4283927B2 - Exhaust manifold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust manifold that collects exhaust gas from each exhaust port of a multi-cylinder engine and sends it to an exhaust pipe.
[0002]
[Prior art]
Conventionally, as shown in FIG. 8, exhaust gas discharged from the engine 100 is sent to the catalytic converter 103 via the exhaust manifold 101 and the exhaust pipe 102 and purified by the catalyst in the catalytic converter 103. The air is exhausted through 104. Since the catalyst is activated at a temperature of about 350 ° C. or higher, when the engine 100 is started, a certain amount of time is required until the catalyst is activated because the temperature of the catalyst is low.
[0003]
Therefore, in order to suppress the decrease in the temperature of exhaust gas sent from the engine 100 to the catalytic converter 103 and activate the catalyst as soon as possible, the exhaust manifold has a low heat capacity. For example, as shown in FIG. 9, the exhaust manifold 101 has a double-pipe structure including thin first to fourth inner pipes 111 to 114 connected to the exhaust ports and a reinforcing case 120 covering them. .
[0004]
First to fourth inner pipes 111 to 114 are connected to first cylinder # 1 to fourth cylinder # 4 of engine 100, respectively. The ignition sequence is the first cylinder # 1, the third cylinder # 3, the second cylinder # 2, and the fourth cylinder # 4, and the first inner pipe 111 and the fourth inner pipe 114 are connected to prevent exhaust interference. And connected to the exhaust pipe. Further, the second inner pipe 112 and the third inner pipe 113 are connected and connected to the exhaust pipe.
[0005]
As a result, the first to fourth inner pipes 111 to 114 having a small heat capacity quickly reach the saturation temperature due to the high-temperature exhaust gas. And the temperature drop of the exhaust gas can be suppressed.
[0006]
[Problems to be solved by the invention]
However, in such a conventional one, the shape of the first to fourth inner pipes 111 to 114 is complicated, and at the same time, the shape of the reinforcing case manufactured according to the shape of the first to fourth inner pipes 111 to 114 However, there is a problem that the machining process becomes complicated.
[0007]
An object of the present invention is to provide an exhaust manifold that has a simple structure, can suppress a decrease in exhaust gas temperature immediately after engine startup, and can quickly increase the temperature of a catalyst.
[0008]
[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 gas from each exhaust port of a multi-cylinder engine and sends it to the exhaust pipe,
A large flange which is formed with each introduction hole corresponding to each exhaust port and is attached to the engine;
An outer shell member attached to the large flange so as to cover the introduction holes and forming an exhaust chamber;
Further, the exhaust chamber is partitioned and a gap is provided between the large flange and a wall plate member having a connecting pipe portion that communicates the exhaust chamber and the introduction holes is provided in the outer shell member. It is the characteristic exhaust manifold.
[0009]
The wall plate member may be formed in a U-shaped cross section. The wall plate member may be provided with a thermal stress absorbing portion that absorbs thermal deformation caused by the exhaust gas, and the thermal stress absorbing portion may form the wall plate member in a bellows shape. Further, the wall plate member may be fixed to the outer wall member.
[0010]
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.
[0011]
The exhaust manifold 1 includes a large flange 2, an outer shell member 4, and a small flange 6. As shown in FIG. 7, the large flange 2 has four introduction holes 10 to 13 corresponding to the first to fourth exhaust ports P <b> 1 to P <b> 4, and the large flange 2 is attached to the engine 100. A plurality of mounting holes 14 for mounting with bolts (not shown) are formed. Furthermore, as shown in FIG. 1, an annular protrusion 16 that protrudes toward the outer shell member 4 is formed so as to surround the four introduction holes 10 to 13.
[0012]
The outer shell member 4 covers all of the four introduction holes 10 to 13 and is fitted inside the annular protrusion 16. The outer shell member 4 and the large flange 2 form an exhaust chamber 18 through which the four introduction holes 10 to 13 communicate. In the outer shell member 4, a recess corresponding to the exhaust chamber 18 is integrally formed by press drawing or the like, and a connecting pipe 20 is inserted into the outer shell member 4. A flange 6 is attached.
[0013]
A wall plate member 22 is disposed in the outer shell member 4, and the wall plate member 22 is formed in a “U” shape in cross section as shown in FIGS. 3 and 4. 4 and the wall plate member 22 form an exhaust gas flow path. Further, the wall plate member 22 is provided over the four introduction holes 10 to 13 along the large flange 2.
[0014]
The wall plate member 22 is arranged so as to partition the exhaust chamber 18 and form a gap 23 between the large flange 2. The wall plate member 22 has connection pipe portions 24 to 27 corresponding to the introduction holes 10 to 13, and the connection pipe portions 24 to 27 and the introduction holes 10 to 13 are communicated with each other. Thermal stress absorbing portions 28 to 30 are formed between the connecting pipe portions 24 to 27, and the thermal stress absorbing portions 28 to 30 are formed by folding the wall plate member 22 into a bellows shape.
[0015]
In this embodiment, the wall plate member 22 has a plurality of wire meshes 32 stacked on the inner surface of the outer shell member 4, and the overlapped portion 34 is fixed by spot welding. Moreover, the places 34 and 36 (refer FIG. 3) which overlapped the outer shell member 4 and the connection pipe parts 24-27 are being fixed to the outer shell member 4 by spot welding.
[0016]
The outer shell member 4 and the large flange 2 are welded to the outer periphery of the outer shell member 4 along the annular protrusion 16 so that the outer shell member 4 and the large flange 2 are integrated. On the other hand, the connecting pipe 20 is inserted into the outer shell member 4 and welded all around, and a small flange 6 is attached to the connecting pipe 20 by welding or the like.
[0017]
Next, the operation of the exhaust manifold 1 of the present embodiment described above will be described.
As the engine 100 is operated, exhaust gas is sequentially discharged from the exhaust ports P1 to P4. The exhaust gas exhausted from the exhaust ports P1 to P4 flows into the exhaust chamber 18 through the introduction holes 10 to 13 and the connection pipe portions 24 to 27, respectively. The exhaust gas is collected in the exhaust chamber 18 and then sent to the exhaust pipe (not shown) through the connection pipe 20.
[0018]
The exhaust gas flowing into the exhaust chamber 18 flows along the wall plate member 22 with a gap from the large flange 2 by the wall plate member 22. Since the large flange 2 is attached to the engine 100 and the engine 100 is water-cooled, its temperature is low. Accordingly, the temperature of the large flange 2 is also low as in the engine 100, and the heat is absorbed by the engine 100. Therefore, even when heated by the exhaust gas, the temperature rise is small and the exhaust gas is cooled.
[0019]
However, by providing the wall plate member 22, the exhaust gas does not contact the large flange 2 and there is a gap 23 between them, so that the amount of heat taken away by the large flange 2 is small. Further, since the wall plate member 22 can be formed with a thin plate thickness, the heat capacity is small, and when the wall plate member 22 is heated by the exhaust gas, it quickly reaches the saturation temperature. Therefore, immediately after the engine 100 is started, the temperature of the exhaust gas sent to the exhaust pipe via the connection pipe 20 rises quickly, and the temperature of the catalyst of the catalytic converter rises quickly, so that the exhaust gas purification is further improved. Can be made.
[0020]
Further, in the exhaust manifold 1 described above, the wall plate member 22 is attached to the press-formed outer shell member 4, and the outer shell member 4 is fitted inside the annular protrusion 16 of the large flange 2. Weld all around along to make it one piece. Therefore, there are few components of the exhaust manifold 1, and a simple dual structure can be obtained with a simple configuration.
[0021]
Since the number of component parts is small, the weight can be reduced, and the outer shell member 4 is attached to the large flange 2 by all-around welding, so that the rigidity is increased and the durability is improved. Furthermore, since it fits inside the annular protrusion 16, positioning of the outer shell member 4 is easy.
[0022]
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.
[0023]
【The invention's effect】
As described above in detail, the exhaust manifold of the present invention has the effect that the number of components is small, a double structure is obtained with a simple configuration, and the temperature of the catalyst at the time of starting the engine can be quickly increased.
[Brief description of the drawings]
FIG. 1 is a plan view of an exhaust manifold as an embodiment of the present invention attached to an engine.
FIG. 2 is a front view of the exhaust manifold of the present embodiment.
FIG. 3 is an enlarged cross-sectional view taken along AA in FIG.
4 is an enlarged sectional view taken on line BB in FIG. 2;
FIG. 5 is an enlarged cross-sectional view of CC in FIG. 2;
6 is a DD cross-sectional view of FIG. 5. FIG.
FIG. 7 is an exploded explanatory view of the exhaust manifold of the present embodiment.
FIG. 8 is an explanatory diagram showing an exhaust system of the internal combustion engine.
FIG. 9 is a front view of a conventional exhaust manifold.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,101 ... Exhaust manifold 2 ... Large flange 4 ... Outer shell member 6 ... Small flange 10-13 ... Introduction hole 16 ... Annular protrusion 18 ... Exhaust chamber 20 ... Connection pipe 22 ... Wall board member 23 ... Gap 24-27 ... Connection pipe part 28-30 ... Thermal stress absorption part 32 ... Wire mesh 100 ... Engine

Claims (5)

In the exhaust manifold that collects exhaust gas from each exhaust port of a multi-cylinder engine and sends it to the exhaust pipe,
A large flange which is formed with each introduction hole corresponding to each exhaust port and is attached to the engine;
An outer shell member attached to the large flange so as to cover the introduction holes and forming an exhaust chamber;
Further, the exhaust chamber is partitioned and a gap is provided between the large flange and a wall plate member having a connecting pipe portion that communicates the exhaust chamber and the introduction holes is provided in the outer shell member. Characteristic exhaust manifold. 2. The exhaust manifold according to claim 1, wherein the wall plate member is formed in a U-shaped cross section. 3. The exhaust manifold according to claim 1, wherein the wall plate member is provided with a thermal stress absorbing portion that absorbs thermal deformation caused by the exhaust gas. 4. The exhaust manifold according to claim 3, wherein the thermal stress absorbing portion is formed with the wall plate member in a bellows shape. 5. The exhaust manifold according to claim 1, wherein the wall plate member is fixed to the outer wall member.

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