JP4282135B2 - Exhaust manifold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust manifold that collects exhaust gases exhausted from exhaust ports of a four-cylinder engine and sends them to an exhaust pipe.
[0002]
[Prior art]
Conventionally, as shown in FIG. 7, the 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, and then the muffler 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 the 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, in the case of the four-cylinder engine 100 shown in FIG. 8, the exhaust manifold 101 is composed of thin first to fourth inner pipes 111 to 114 connected to each exhaust port and a reinforcing case 120 covering these. It has a double tube structure.
[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 fourth cylinder # 4, and the second cylinder # 2, 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. Moreover, since exhaust interference is prevented, it is possible to suppress a decrease in power performance.
[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, the machining process is complicated, and the reinforcing case is also large, so that the surface area is large, the heat is radiated through the reinforcing case, and the temperature reduction of the exhaust gas is not sufficiently suppressed.
[0007]
An object of the present invention is to provide an exhaust manifold that can suppress a decrease in the temperature of exhaust gas immediately after engine startup, can quickly increase the temperature of a catalyst, and can prevent exhaust interference.
[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 .
[0009]
That is, an exhaust pipe is connected to a collecting pipe portion in which branch pipe portions connected to first to fourth exhaust ports of a four-cylinder engine are gathered, and exhaust gas exhausted from the first to fourth exhaust ports is exhausted. In the exhaust manifold to send to
The order of exhaust from the first to fourth exhaust ports is first, third, fourth, second,
A partition pipe communicating with the second and third exhaust ports is provided in the branch pipe part communicating with the second and third exhaust ports until reaching the collecting pipe part from the branch pipe part, An exhaust manifold is characterized by being opened in the collecting pipe .
[0010]
Further, the branch pipe portion may be configured to communicate with the first exhaust port, the second and third exhaust ports, and the fourth exhaust port, respectively.
[0011]
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 four-cylinder engine 100 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. In this embodiment, ignition is performed in the order of the first cylinder # 1, the third cylinder # 3, the fourth cylinder # 4, and the second cylinder # 2.
[0012]
The exhaust manifold 1 includes a large flange 2, an outer case 4, a partition pipe 6, and a small flange 8. As shown in FIG. 2, the large flange 2 has four through 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 to 18 for mounting with bolts (not shown) are formed. As shown in FIG. 5, annular protrusions 20 to 23 that protrude toward the outer case 4 are formed around the four through holes 10 to 13.
[0013]
The outer case 4 includes first to third branch pipe portions 24 to 26 and a collecting pipe portion 28 connected to the first to third branch pipe portions 24 to 26. In this embodiment, the outer case 4 is formed in a hollow shape by press working, and is formed so that the cross-sectional area decreases from the first to third branch pipe portions 24 to 26 side toward the collecting pipe portion 28 side. ing.
[0014]
An opening 29 is formed at the end of the collecting pipe portion 28. A small flange 8 is attached to the exhaust manifold 1 on the opening 29 side, and the small flange 8 is flange-coupled to an exhaust pipe (not shown). The outer case 4 has a relatively large thickness, and is formed to be 1.5 mm in this embodiment.
[0015]
On the other hand, as shown in FIG. 2, the first to third branch pipe portions 24 to 26 are separated by the recessed portions 30 and 32 that are recessed by overlapping the front and back sides of the outer case 4. The first branch pipe portion 24 and the third branch pipe portion 26 are formed in a substantially circular shape, and the second branch pipe portion 25 is formed in an oval shape so as to straddle the second and third exhaust ports P2 and P3. ing. In the present embodiment, a recess 33 is formed in the second branch pipe portion 25 so that a bolt can be inserted into the mounting hole 16.
[0016]
As shown in FIG. 2, the first branch pipe portion 24 is fitted into the annular protrusion 20 of the through hole 10 communicating with the first exhaust port P1, and the first branch pipe portion 24 and the first exhaust port P1 communicate with each other. Has been. The third branch pipe portion 26 is fitted to the annular protrusion 23 of the through hole 13 communicating with the fourth exhaust port P4, and the third branch pipe portion 26 and the fourth exhaust port P4 are communicated with each other.
[0017]
The partition tube 6 is also formed hollow by molding using a press, and in this embodiment, the wall thickness is as thin as 0.8 mm. The partition pipe 6 is provided with first and second branch pipe parts 34 and 36 and a junction pipe part 38 connected to the first and second branch pipe parts 34 and 36.
[0018]
As shown in FIG. 2, the first and second branch pipe portions 34 and 36 are separated by a concave portion 40 in which both front and back sides of the partition pipe 6 are recessed and overlapped. It is formed in a substantially circular shape. And the 1st, 2nd branch pipe parts 34 and 36 are joined by the junction pipe part 38, and the opening 37 is formed in the other end side of the junction pipe part 38 (refer FIG. 3).
[0019]
The first branch pipe portion 34 is fitted to the annular protrusion 21 of the through hole 11 communicated with the second exhaust port P2, and the second branch pipe portion 36 is annular of the through hole 12 communicated with the third exhaust port P3. The protrusion 22 is fitted. As shown in FIG. 5, the outer case 4 is put on the partition pipe 6, and the second branch pipe portion 25 of the outer case 4 is connected to the first and second branch pipe portions 34 and 36 as shown in FIG. 2. It is mounted on both annular protrusions 21 and 22 from above. Then, welding is performed along the outer periphery of the outer case 4, and the outer case 4 and the partition pipe 6 are integrally attached to the large flange 2.
[0020]
The first exhaust port P1 communicates with the opening 29 through the through hole 10, the first branch pipe portion 24, and the collecting pipe portion 28, and exhaust gas is sent from the opening 29 to the exhaust pipe. The second exhaust port P2 communicates with the opening 29 through the through hole 11, the first branch pipe section 34, the merging pipe section 38, the opening 37, and the collecting pipe section 28, and exhaust gas is sent from the opening 29 to the exhaust pipe. .
[0021]
The third exhaust port P3 communicates with the opening 29 through the through hole 12, the second branch pipe section 36, the merging pipe section 38, the opening 37, and the collecting pipe section 28, and exhaust gas is sent from the opening 29 to the exhaust pipe. . The fourth exhaust port P4 communicates with the opening 29 through the through hole 13, the third branch pipe part 26, and the collecting pipe part 28, and exhaust gas is sent from the opening 29 to the exhaust pipe.
[0022]
Moreover, the opening 37 of the partition pipe 6 is disposed in the middle of the collecting pipe portion 28 of the outer case 4, and the length from the large flange 2 to the opening 37 of the partition pipe 6 is long enough to prevent exhaust interference. Is formed. The cross-sectional area of the flow path that communicates each of the exhaust ports P1 to P4 and the opening 29 of the outer case 4 is formed to be approximately the same or slightly larger at each location.
[0023]
Next, the operation of the exhaust manifold of the present embodiment described above will be described.
Exhaust gas resulting from combustion in the first cylinder # 1 flows from the first exhaust port P1 through the through hole 10 into the first branch pipe portion 24. Then, it passes through the collecting pipe portion 28 and is sent to an exhaust pipe (not shown). Next, the exhaust gas generated by combustion in the third cylinder # 3 flows into the second branch pipe portion 36 of the partition pipe 6 through the through hole 12 from the third exhaust port P3. Then, it passes through the partition pipe 6, flows into the collecting pipe portion 28 from the opening 37, and is sent from the collecting pipe portion 28 to the exhaust pipe.
[0024]
Subsequently, the exhaust gas generated by combustion in the fourth cylinder # 4 flows from the fourth exhaust port P4 through the through hole 13 into the third branch pipe portion 26. Then, it passes through the collecting pipe portion 28 and is sent to an exhaust pipe (not shown). At that time, combustion is continued in the third cylinder # 3 and the fourth cylinder # 4, the exhaust order is continued in the third exhaust port P3 and the fourth exhaust port P4, and the exhaust ports P3 and P4 are adjacent to each other. ing. However, the partition pipe 6 suppresses the exhaust gas from the third exhaust port P3 from flowing into the fourth exhaust port P4 side, thereby preventing exhaust interference.
[0025]
Next, the exhaust gas resulting from combustion in the second cylinder # 2 flows into the first branch pipe portion 34 of the partition pipe 6 through the through hole 11 from the second exhaust port P2. Then, it passes through the partition pipe 6, flows into the collecting pipe portion 28 from the opening 37, and is sent from the collecting pipe portion 28 to the exhaust pipe. The operation described above is repeated, and the exhaust gas flows into the first branch pipe portion 24 by the combustion in the first cylinder # 1.
[0026]
At that time, the exhaust order of the second exhaust port P2 and the first exhaust port P1 is continuous, and the exhaust ports P1 and P2 are adjacent to each other. However, the partition pipe 6 suppresses the exhaust gas from the second exhaust port P2 from flowing into the first exhaust port P1 side, thereby preventing exhaust interference.
[0027]
On the other hand, when the engine 100 is started, the temperature of the outer case 4 and the partition pipe 6 is low, and the heat of the exhaust gas is taken away by the outer case 4 and the partition pipe 6. However, the heat capacity of the partition tube 6 is small, and the temperature of the partition tube 6 quickly rises due to the heat of the exhaust gas. Also within the outer case 4, may be housed the partition tube 6 short lengths, you are possible to reduce the outer shape of the outer case 4, by this, since also small surface area of the outer case 4 through the outer case 4 heat radiated to the external is small.
[0028]
Therefore, as shown in FIG. 6, the temperature of the exhaust gas passing through the exhaust manifold 1 is recovered in a short time, and the temperature decrease of the exhaust gas is suppressed .
[0029]
That is, when the exhaust manifold 1 of the present embodiment is used, the time until the exhaust gas temperature recovers to 350 ° C. is shortened as compared with the case of the conventional double-pipe exhaust manifold indicated by the one-dot chain line.
[0030]
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.
[0031]
【The invention's effect】
As described in detail above, the exhaust manifold of the present invention has a small heat capacity and a small surface area. There is an effect that the catalyst purification efficiency can be improved. Further, since exhaust interference can be prevented, the output torque of the engine is not reduced. Furthermore, the structure of the partition tube is simple, and it can be manufactured easily and at a low cost.
[Brief description of the drawings]
FIG. 1 is a front view of an exhaust manifold as one embodiment of the present invention.
2 is a cross-sectional view taken along the line AA of FIG.
FIG. 3 is a side view showing a part of the exhaust manifold according to the embodiment in a cutaway manner.
4 is a BB cross-sectional view of FIG.
FIG. 5 is an exploded explanatory view of an exhaust manifold according to the present embodiment.
FIG. 6 is a graph showing temperature characteristics of the exhaust manifold of the present embodiment.
FIG. 7 is an explanatory diagram showing an exhaust system of the internal combustion engine.
FIG. 8 is a front view of a conventional exhaust manifold.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,101 ... Exhaust manifold 2 ... Large flange 4 ... Outer case 6 ... Partition pipe 8 ... Small flange 10-13 ... Through-hole 14-18 ... Mounting hole 20-23 ... Annular protrusion 24 ... 1st branch pipe part 25 ... 2nd branch pipe part 26 ... 3rd branch pipe part 28 ... Collecting pipe part 30, 32 ... Depression part 34 ... 1st branch pipe part 36 ... 2nd branch pipe part 37 ... Opening 38 ... Depression part 38 ... Confluence pipe part 100 …engine

Claims (2)

An exhaust pipe is connected to a collecting pipe part in which branch pipe parts connected to the first to fourth exhaust ports of the four-cylinder engine are gathered, and exhaust gas exhausted from the first to fourth exhaust ports is sent to the exhaust pipe. In the exhaust manifold,
The order of exhaust from the first to fourth exhaust ports is first, third, fourth, second,
A partition pipe communicating with the second and third exhaust ports is provided in the branch pipe part communicating with the second and third exhaust ports until reaching the collecting pipe part from the branch pipe part, An exhaust manifold having an opening in the collecting pipe portion. 2. The exhaust manifold according to claim 1, wherein the branch pipe portion communicates with the first exhaust port, the second and third exhaust ports, and the fourth exhaust port.

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