JP2012202284A - Cooling structure of exhaust manifold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling structure of an exhaust manifold that can improve the cooling efficiency of exhaust gas exhausted from a cylinder of an engine, and can prevent the breakage or deformation of a branch pipe and its cooling parts even if a thermal expansion difference is generated between the branch pipe and the cooling parts.SOLUTION: The cooling structure of the exhaust manifold includes header pipes 2 for flowing exhaust gas exhausted from an engine 1 to its downstream end of exhaust gas where the upstream end of exhaust gas is connected to each cylinder of the engine 1, and a coolant passage pipe 5 for cooling the exhaust gas G flowing in each of the header pipes 2 independently by coolant water flowing through the coolant passage pipe in a state of contacting with the header pipes 2. The header pipe 2 is composed of two-divided header pipes 2a and 2b, and an outer circumferential surface of the coolant passage pipe 5 is sandwiched by the split pipes so as to be relatively displaceable.

Description

  The present invention relates to an exhaust manifold cooling structure capable of cooling exhaust gas discharged from a cylinder of an engine mounted on an automobile or the like.

  Conventionally, in the exhaust manifold connected to the engine, the exhaust manifold cooling structure that cools the exhaust gas discharged from the cylinder of the engine with cooling water has been used to improve the durability of the exhaust system components such as the exhaust manifold and the catalyst. It is improving.

  As such a conventional exhaust manifold cooling structure, a water jacket is provided in the exhaust manifold connected to each cylinder of the automobile engine at least in the branch pipe corresponding to each cylinder of the engine and the exhaust gas passage of the main pipe. It is known that a water-cooling part including the gas-cooling part is provided so as to divide the exhaust gas flow in the branch pipe into two parts to cool the exhaust gas flowing through the branch pipe (see, for example, Patent Document 1).

JP 2010-203300 A

However, the conventional exhaust manifold cooling structure has the following problems.
In other words, the water jacket in the water-cooled section remains sealed and is not designed to circulate engine cooling water, etc., so that the cooling effect is demonstrated when the water in the water jacket warms up after the engine has been running. become unable.
Further, the above publication only discloses that the water cooling part is sandwiched between the branch pipe and the main pipe, and it is unclear whether it is fixed or not. If it is fixed, a stress based on a difference in thermal expansion occurs between the water-cooled part and the branch pipe (or main pipe), and these are damaged or deformed. On the other hand, assuming that it is press-fitted rather than fixed, the thermal expansion of the branch pipe (or main pipe) exposed to the high-temperature exhaust gas that has just been exhausted from the engine cylinder is greater than that of the water-cooled part having the water jacket, The water-cooled part will rattle in the branch pipe (or main pipe).
Further, since the water cooling part is provided in the exhaust gas passage, if the water cooling part is damaged due to the above causes and the water in the water jacket enters the branch pipe or the main pipe, Adversely affect.

  The present invention has been made paying attention to the above problems, and the object of the present invention is to improve the cooling efficiency of the exhaust gas discharged from the cylinder of the engine, and between the branch pipe of the exhaust manifold and its cooling part. Thus, it is an object of the present invention to provide a cooling structure for an exhaust manifold that does not break or deform even when a difference in thermal expansion occurs.

For this purpose, the cooling structure of the exhaust manifold according to the first invention is as follows.
An exhaust gas upstream end is connected to each cylinder of the engine, and a branch pipe through which exhaust gas discharged from the engine flows to the exhaust gas downstream end,
A cooling water channel pipe that cools the exhaust gas flowing through each branch pipe independently of each other by circulating cooling water inside the branch pipe,
In the exhaust manifold cooling structure with
The branch pipe is composed of two divided pipes, and the outer peripheral surface of the cooling water pipe is sandwiched between these pipes so as to be capable of relative displacement.
It is characterized by that.

For this purpose, the exhaust manifold cooling structure according to the second invention is:
An exhaust gas upstream end is connected to each cylinder of the engine, and a branch pipe through which exhaust gas discharged from the engine flows to the exhaust gas downstream end,
A cooling water channel pipe that cools the exhaust gas flowing through each branch pipe independently of each other by circulating cooling water inside the branch pipe,
In the exhaust manifold cooling structure with
The cooling water channel pipe is composed of two divided pipes, and the outer peripheral surface of the branch pipe is sandwiched by these pipes so as to be capable of relative displacement.
It is characterized by that.

The exhaust manifold cooling structure according to the third invention is
In the exhaust manifold cooling structure of the first or second invention,
The pipe divided into two parts is pressed so as to come into contact with the outer peripheral surface of the other party sandwiched between them by elastic force.
It is characterized by that.

In the exhaust manifold cooling structure according to the first aspect of the invention, the branch pipe is constituted by two divided pipes, and the outer peripheral surface of the cooling water pipe is sandwiched by these pipes so as to be relatively displaceable. The cooling efficiency can be maintained and improved by circulating the pipe water to the radiator as engine cooling water, for example.
Further, even if a difference in thermal expansion occurs between the branch pipe and the cooling water pipe, they can be displaced relative to each other, and damage and deformation can be avoided.
In the unlikely event that the cooling water channel pipe breaks, the water inside the cooling water pipe does not enter the branch pipe, so there is no fear of adversely affecting the catalyst or the like.

In the cooling structure for the exhaust manifold according to the second aspect of the invention, the cooling water pipe is composed of two divided pipes, and the outer peripheral surface of the branch pipe is sandwiched between these pipes so as to be relatively displaceable. The cooling efficiency can be maintained and improved by circulating the pipe water to the radiator as engine cooling water, for example.
Further, even if a difference in thermal expansion occurs between the branch pipe and the cooling water pipe, they can be displaced from each other, and damage and deformation can be avoided.
In the unlikely event that the cooling water channel pipe breaks, the water inside the cooling water pipe does not enter the branch pipe, so there is no fear of adversely affecting the catalyst or the like.

In the exhaust manifold cooling structure of the third invention,
Since the pipe divided into two is pressed by the elastic force so as to contact the outer peripheral surface of the other party sandwiched between them, the divided pipe and the other party sandwiched between them are constantly in contact with each other, and the decrease in cooling effect is suppressed. It becomes possible to do.

It is a top view which shows the cooling structure of the exhaust manifold which concerns on Example 1 of this invention. It is a longitudinal cross-sectional view in the S2-S2 line of FIG. It is a longitudinal cross-sectional view in the S3-S3 line of FIG. It is a top view which shows the cooling structure of the exhaust manifold which concerns on Example 2 of this invention. It is a longitudinal cross-sectional view in the S5-S5 line of FIG. It is a longitudinal cross-sectional view in the S6-S6 line of FIG.

  Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.

  First, the overall configuration of the exhaust manifold cooling structure according to the first embodiment will be described with reference to FIGS. In the first embodiment, a cooling structure of the exhaust manifold M applied to an in-line four-cylinder engine mounted on an automobile will be described as an example.

  The cooling structure of the exhaust manifold M according to the first embodiment has four header pipes connected to each cylinder of the in-line four-cylinder engine 1 to flow exhaust gas exhausted from the four-cylinder engine 1 to the exhaust gas downstream side (the present invention). 2), an upstream exhaust manifold UM having a manifold 7 connected to the downstream side for flowing exhaust gas and a downstream exhaust manifold DM having a collector 7a, and an exhaust gas G flowing in the header pipe 2. And a cooling water pipe 5 for cooling the water.

  At the exhaust gas upstream end (engine side end) of each header pipe 2, an engine side flange 3 is provided and attached to the side surface of the cylinder head of the in-line four-cylinder engine 1 as shown in FIG. On the other hand, an intermediate flange 3 is provided at the exhaust gas downstream end (exhaust pipe side end) of each header pipe 2 to which the exhaust gas upstream end is connected.

  The exhaust pipe upstream end of the manifold pipe 7 is provided with an intermediate flange 7c connected to the intermediate flange 3 of the header pipe 2, and the exhaust gas downstream end thereof is combined into one by the collector 7a, An exhaust pipe flange 7c is provided at the exhaust gas downstream end of the collector 7a. The exhaust pipe side flange 7c is connected to a downstream exhaust pipe provided with a catalyst, a muffler, etc. (not shown).

As shown in FIGS. 2 and 3, the header pipe 2 is divided into two in the vertical direction from the center of the circular pipe, and a gap 2c is formed at the center in the longitudinal direction of the divided header pipes (two divided pipes) 2a and 2b. Has been.
The cooling water channel pipe 5 has a flat shape with a long cross section in the longitudinal direction of the header pipe 2, and penetrates and extends in a state where the gap 2 c between both the divided header pipes 2 a and 2 b is continuous in the longitudinal direction of the four-cylinder engine 1. The outer peripheral surface of the cooling water pipe 5 is sandwiched between the flat lower surface of the upper divided header pipe 2a and the flat upper surface of the lower divided header pipe 2b so as to be in contact with and relatively displaceable. In this case, the divided header pipes 2a and 2b are contacted between the contact surfaces of the divided header pipes 2a and 2b and the cooling channel pipe 5 by these elastic forces or elastic bands (not shown) wound around the outer circumference of the divided header pipes 2a and 2b. Is crimped.

Next, the operation of the exhaust manifold cooling structure according to the first embodiment will be described.
Since the exhaust manifold cooling structure of the first embodiment is configured as described above, the exhaust gas G discharged from each cylinder of the in-line four-cylinder engine 1 is exhausted upstream as shown in FIGS. It flows into the manifold pipe 7 of the downstream side exhaust manifold DM via both divided header pipes 2a and 2b of each header pipe 2 of the manifold UM. The exhaust gas flowing into the manifold pipes 7a in the downstream exhaust manifold 7 is integrated in the collector portion 7b and flows into a downstream exhaust pipe, catalyst, muffler, etc. (not shown) and is purified and silenced. It is discharged outside the car.

  On the other hand, as shown in FIG. 2, the cooling water supplied to the cooling water pipe 5 from a radiator or the like outside the figure flows in the cooling water pipe 5 from the right to the left in FIG. The exhaust gas G flowing in the two divided header pipes 2a and 2b is cooled by removing heat from the exhaust gas G through the contact surface of the two divided header pipes 2a and 2b with the outer peripheral surface of the cooling water pipe 5.

  When the exhaust gas G becomes high temperature due to long-time operation of the engine or operation with high output, the above cooling is performed, but the temperature of the exhaust gas G suddenly rises during acceleration or the like, and the cooling by the cooling water pipe 5 Over capacity. As a result, there may be a difference in thermal expansion between the two divided header pipes 2a, 2b and the cooling water pipe 5 in the width direction, the thickness direction, the longitudinal direction, etc. In this case, the two divided header pipes 2a, The contact surface 2b and the cooling water channel pipe 5 are relatively displaced by sliding or elastically deforming in the above-described directions only by their contact surfaces being crimped by an elastic force. Therefore, an excessive stress due to a difference in thermal expansion is suppressed between them, thereby preventing breakage and problematic plastic deformation. Moreover, since both the divided header pipes 2a and 2b and the cooling water channel pipe 5 are always in contact, it is possible to suppress a decrease in cooling capacity.

  Also, even if the cooling water channel pipe 5 is damaged and the water in the interior leaks, the water leaking into the interior of the two divided header pipes 2a and 2b enters, and adversely affects the downstream catalyst and the like. Is prevented.

Next, the effect of the exhaust manifold cooling structure according to Embodiment 1 of the present invention will be described.
(1) In the exhaust manifold cooling structure according to the first embodiment, the header pipe 2 is composed of two divided header pipes 2a and 2b, and the outer peripheral surface of the cooling water channel pipe 5 is formed by the two divided header pipes 2a and 2b. As a result, the cooling water can be circulated to the radiator as engine cooling water, for example, as a result of cooling through the contact surface, thereby improving the cooling efficiency. In this case, since the contact surfaces of the divided header pipes 2a and 2b and the cooling water pipe 5 are pressed by an elastic force, they are in contact with each other during use, thereby suppressing a decrease in cooling capacity. be able to.

 (2) Even if a difference in thermal expansion occurs between the two divided header pipes 2a, 2b and the cooling water pipe 5, they can be displaced relative to each other, avoiding excessive stress, Can avoid damage and deformation.

 (3) Even if the cooling water channel pipe 5 is broken, the water inside the pipe does not enter the two divided header pipes 2a and 2b.

  Next, another embodiment of the present invention will be described. In the description of the other embodiments, the same components as those of the first embodiment are not shown, or the same reference numerals are given and the description thereof is omitted, and only the differences are described.

  As shown in FIGS. 4 to 6, the cooling structure of the exhaust manifold of the second embodiment is such that the header pipe 2 is cylindrical, and the cooling water pipe 6 is composed of pipes divided into two in the vertical direction. The point which made the state which the outer peripheral surface of the header pipe 2 was pinched | interposed so that contact and relative displacement were possible differs from the said Example 1. FIG.

  That is, in the second embodiment, the upper cooling water pipe 6a that is continuous in the longitudinal direction of the four-cylinder engine 1 along the outer periphery of the header pipe 2, that is, the upper outer peripheral surface of the four header pipes 2, and the four headers. A lower cooling water pipe 6b that is continuous in the longitudinal direction of the four-cylinder engine 1 along the lower outer peripheral surface of the pipe 2 is provided.

And this upper side cooling water pipe 6a and the lower side cooling water pipe 6b are provided in the state which pinched | interposed the outer peripheral surface of the header pipe 2 so that relative displacement was possible along the longitudinal direction. The upper cooling water channel pipe 6a and the lower cooling water channel pipe 6b maintain contact with the header pipe 2 by these elastic forces or elastic forces such as an elastic band (not shown) wound around the outer peripheral surface.
In the second embodiment, the flow directions of the cooling water in the upper cooling water channel pipe 6a and the lower cooling water channel pipe 6b are opposite to each other.

Next, the operation of the second embodiment will be described.
Since the exhaust manifold cooling structure of the second embodiment is configured as described above, the cooling water supplied to the cooling water channel pipe 5 is located above the four header pipes 2 as shown in FIGS. It flows in the header pipe 2 by flowing in the upper cooling water channel pipe 6a provided along the outer peripheral surface and the lower cooling water channel pipe 6b provided in the lower outer peripheral surface of the four header pipes 2. The exhaust gas G is cooled.

Next, the effect of the exhaust manifold according to the second embodiment of the present invention will be described.
(1) In the exhaust manifold cooling structure of the first embodiment, the cooling water pipe is composed of an upper cooling water pipe 6a and a lower cooling water pipe 6b which are divided into upper and lower parts, and these pipes make the header pipe 2 Since the outer peripheral surfaces of the upper and lower cooling water channel pipes 6a and 6b are circulated to the radiator as engine cooling water, for example, the cooling efficiency can be maintained and improved. it can.

 (2) Even if a thermal expansion difference occurs between the header pipe 2 and the upper cooling water channel pipe 6a and the lower cooling water channel pipe 6b, they can be displaced relative to each other, and damage and deformation can be avoided.

 (3) Even if the upper cooling water pipe 6a or the lower cooling water pipe 6b is broken, the water inside the header pipe 2 does not enter the header pipe 2, so that there is no fear of adversely affecting the catalyst or the like.

 (4) Further, the flow direction of the cooling water in the upper and lower cooling water channel pipes 6a and 6b divided into two in the upper and lower directions is made opposite to each other so that the exhaust gas G flowing in the four header pipes 2 Variations in the cooling effect can be suppressed.

  The present invention has been described based on the above embodiments. However, the present invention is not limited to these embodiments, and is included in the present invention even when there is a design change or the like without departing from the gist of the present invention. .

  For example, in the present embodiment, in the present embodiment, the upstream branch pipe 2 and the downstream manifold pipe 7a are divided and connected by the intermediate flanges 4 and 7c, but the intermediate flanges 4 and 7c are not integrated. You may comprise as a molded article.

Further, the structure of the second embodiment may be combined with the structure of the first embodiment.
In addition, a control valve may be provided in the circulating water channel to the cooling water channel pipe, and a control unit that controls the flow rate of the cooling water according to the temperature of the exhaust gas G may be provided.
Moreover, although the example applied to the in-line four-cylinder engine is shown in the embodiment, it can be applied to all types of engines.

1 Inline 4-cylinder engine 2 Header pipe (branch pipe)
2a Upper divided header pipe 2b Lower divided header pipe 2c Clearance 3 Engine side flange 4 Intermediate flange 5 Cooling water pipe 6 Cooling water pipe 6a Upper cooling water pipe 6b Lower cooling water pipe 7 Divergent pipe 7a Collector 7b Intermediate flange 7c Exhaust pipe side flange M Exhaust manifold UM Upstream exhaust manifold DM Downstream exhaust manifold G Exhaust gas

Claims (3)

An exhaust gas upstream end is connected to each cylinder of the engine, and a branch pipe through which exhaust gas discharged from the engine flows to the exhaust gas downstream end,
A cooling water pipe that cools the exhaust gas flowing in each of the branch pipes independently of each other by circulating cooling water inside the branch pipe,
In the exhaust manifold cooling structure with
The branch pipe is composed of two divided pipes, and the outer peripheral surface of the cooling water pipe is sandwiched between these pipes so as to be capable of relative displacement.
An exhaust manifold cooling structure characterized by this. An exhaust gas upstream end is connected to each cylinder of the engine, and a branch pipe through which exhaust gas discharged from the engine flows to the exhaust gas downstream end,
A cooling water pipe that cools the exhaust gas flowing in each of the branch pipes independently of each other by circulating cooling water inside the branch pipe,
In the exhaust manifold cooling structure with
The cooling water pipe is composed of two divided pipes, and the outer peripheral surface of the branch pipe is sandwiched between these pipes so as to be capable of relative displacement.
An exhaust manifold cooling structure characterized by this. The exhaust manifold cooling structure according to claim 1 or 2,
The pipe divided into two is pressed so as to come into contact with the outer peripheral surface of the opponent sandwiched between them by elastic force,
An exhaust manifold cooling structure characterized by this.

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