JP2015200236A - EGR cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR cooler which has a simple structure needing only a small number of manufacturing processes, is easily assembled, and improves the durability compared to a conventional EGR cooler.SOLUTION: An EGR cooler 40 cools an exhaust gas of an internal combustion engine and includes: a cylinder head 3 having a coolant circulation part 51; an upstream side EGR pipe 52 in which the exhaust gas is circulated; and a support ring 53 supporting the upstream side EGR pipe 52 on the cylinder head 3. The cylinder head 3 includes: an insertion hole 62a formed at the upstream side of the exhaust gas; and a through hole 63a formed at the downstream side of the exhaust gas. The upstream side EGR pipe 52 includes: a flange 72 fixed to the outer side of the cylinder head 3; and an attachment part 71e to which the support ring 53 is attached. The EGR cooler conducts heat exchange between a coolant circulating in the coolant circulation part 51 and the exhaust gas circulating in the upstream side EGR pipe 52.

Description

  The present invention relates to an EGR (Exhaust Gas Recirculation) cooler, and more particularly to an EGR cooler provided in a cylinder head of an internal combustion engine.

  Conventionally, as this type of EGR cooler, for example, as described in Patent Document 1, a stretchable absorbing member fixed to a housing, an exhaust gas recirculation pipe, and an exhaust gas recirculation pipe and joined to the housing by welding or pressure welding The one with is proposed.

  The housing forms a cooling water outlet passage on one end side of the cylinder head, and the exhaust gas recirculation pipe is supported by the housing in the cooling water outlet passage, and is configured to cool the exhaust gas and return it to the intake passage. The The expansion / contraction absorbing member has an annular concavo-convex portion whose section is curved so as to form a concavo-convex shape in the radial direction that expands and contracts around the end portion of the exhaust gas recirculation pipe. When it does, it absorbs the expansion and contraction at the uneven part.

  The conventional EGR cooler absorbs expansion and contraction of the exhaust gas recirculation pipe with respect to the housing by the expansion and contraction absorbing member, thereby relieving thermal stress generated at the joint portion of the exhaust gas recirculation pipe to the housing.

Japanese Patent No. 5051212

  However, the conventional EGR cooler described in Patent Document 1 has a problem in that the manufacturing process of the stretchable absorbent member is increased in order to form irregularities on the stretchable absorbent member. In addition, the conventional EGR cooler has the holding plate portion of the expansion / contraction absorbing member fixed to the exhaust gas recirculation tube at both ends of the exhaust gas recirculation tube, and the uneven portion of the expansion / contraction absorption member is joined to the housing. There is a problem that a joining process is required. Furthermore, the conventional EGR cooler has a problem that the work of assembling the exhaust gas recirculation pipe to the housing becomes complicated.

  The present invention has been made to solve the above-described problems, and can be easily assembled with a simple structure with fewer manufacturing steps and improve durability as compared with the conventional one. It is an object of the present invention to provide an EGR cooler capable of performing the above.

  In order to solve the above problems, a first aspect of the present invention is an EGR cooler that cools the exhaust gas recirculated from the exhaust passage of the internal combustion engine to the intake passage, and includes a cooling water circulation portion that circulates the cooling water. A housing having an exhaust gas distribution pipe that distributes the exhaust gas from the upstream side to the downstream side in the cooling water distribution part, and a support that supports the exhaust gas distribution pipe to the housing. And a housing having an insertion hole formed on the upstream side so that the exhaust gas circulation pipe is inserted into the cooling water circulation part, and a through hole formed on the downstream side to hold the support ring. The exhaust gas distribution pipe has a flange portion fixed to the outside of the housing on the upstream side and a mounting portion for mounting the support ring on the downstream side, and circulates in the cooling water distribution portion. It consists of the components to be heat exchanged with the exhaust gas flowing in 却水 and the exhaust gas circulation pipe.

  As a second aspect of the present invention, the flange portion of the exhaust gas circulation pipe is connected to a connection flange portion provided at an end portion of the exhaust pipe that allows the exhaust gas to flow on the side surface opposite to the side surface that contacts the housing. You may make it do.

  As a third aspect of the present invention, the housing may be a part of a cylinder head constituting the internal combustion engine, and the cooling water may be constituted by cooling water for cooling the internal combustion engine.

  Thus, according to said 1st aspect, since an exhaust-gas distribution | circulation pipe is comprised by the simple structure which has a flange part which fixes to a housing, and a mounting part which mounts a support ring, compared with the conventional one And the manufacturing process of an EGR cooler decreases.

  In addition, the support ring is mounted on the mounting portion, and the exhaust gas distribution pipe is inserted into the housing and the flange portion is fixed to the housing with the support ring mounted. As a result, the assembly process is reduced as compared with the conventional one, and the exhaust gas distribution pipe can be easily assembled to the housing.

  Further, the downstream end of the exhaust gas circulation pipe becomes a free end, and the exhaust gas circulation pipe is supported by the housing by the support ring and the expansion and contraction of the exhaust gas circulation pipe with respect to the housing is absorbed. No thermal stress is generated on the pipe. As a result, the exhaust gas circulation pipe is not damaged by the thermal stress, so that the durability of the EGR cooler is improved.

  According to said 2nd aspect, since the flange part of an exhaust-gas distribution | circulation pipe is connected with the connection flange part of an exhaust pipe, the deformation | transformation of the exhaust pipe located in the exterior of a housing is exhausted in the inside of a housing. The gas distribution pipe is no longer affected.

  As a result, the deformation amount of the exhaust gas circulation pipe is reduced, and stress due to the deformation of the exhaust pipe is not generated in the exhaust gas circulation pipe, so that the sealing performance of the EGR cooler is maintained and the durability is improved.

  According to said 3rd aspect, since a housing is comprised by a part of cylinder head and cooling water is comprised by the cooling water which cools an internal combustion engine, an EGR cooler protrudes and is provided in the exterior of a cylinder head. Therefore, space saving of the internal combustion engine can be achieved.

  Further, since the housing is not manufactured separately from the cylinder head, manufacturing processes such as component manufacturing and assembly are reduced as compared with the conventional one. Further, since the housing is constituted by a part of the cylinder head, the number of pipes through which the cooling water for cooling the internal combustion engine flows to the EGR cooler is reduced, and the number of manufacturing processes such as parts manufacture and assembly is reduced.

FIG. 1 is a perspective view of an internal combustion engine equipped with an EGR cooler according to an embodiment of the present invention. FIG. 2 is a left side view of the internal combustion engine when the internal combustion engine equipped with the EGR cooler according to the embodiment of the present invention is viewed from the left side of the vehicle. FIG. 3 is a schematic view schematically showing a cross section of a main part of the EGR cooler according to the embodiment of the present invention. FIG. 4 is a schematic view schematically showing a cross section of a main part of another EGR cooler according to the embodiment of the present invention.

  Hereinafter, an EGR cooler 40 according to an embodiment in which the EGR cooler according to the present invention is applied to an internal combustion engine 1 mounted on a vehicle will be described with reference to the drawings.

First, the configuration will be described.
As shown in FIGS. 1 and 2, the internal combustion engine 1 includes a cylinder block 2, a cylinder head 3, an EGR device 4, a cylinder head cover 5, an exhaust manifold 6, an intake manifold 7, and an exhaust gas purification device 8. It is comprised including. The internal combustion engine 1 includes a radiator device (not shown) and a circulation pump that exchange heat in the cooling water for cooling the internal combustion engine 1 and circulate the internal combustion engine 1.

  This cooling water is supplied from the radiator device into the cylinder block 2 by a circulation pump, and after flowing through the cylinder head 3 from the cylinder block 2, returns to the radiator device from the cylinder head 3. The recirculated cooling water is again heat-exchanged between the cooling water and the outside air by the radiator device, and is supplied into the cylinder block 2.

  The internal combustion engine 1 is a four-cycle engine that performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while a piston (not shown) accommodated in a cylinder block 2 reciprocates the cylinder twice. It consists of a 4-cylinder horizontal engine.

  The cylinder block 2 is attached to a vehicle body (not shown) on which the internal combustion engine 1 is mounted via an engine mount, and accommodates a crankshaft that is connected to the piston and converts the reciprocating motion of the piston into a rotational motion.

  An oil pan 2a for storing oil that lubricates the internal combustion engine 1 is attached to the lower part of the cylinder block 2, and the oil in the oil pan 2a is supplied into the internal combustion engine 1 by a pump (not shown). After each component is lubricated, it is returned to the oil pan 2a.

  In the cylinder block 2, a water jacket (not shown) for circulating cooling water is formed, and the cylinder block 2 is cooled by the cooling water flowing in the water jacket.

  The cylinder head 3 is attached to the upper part of the cylinder block 2, and a cooling water circulation part 51, which will be described later, constituting the EGR cooler 40 is formed therein. The cylinder head 3 houses an intake camshaft, an exhaust camshaft, an intake valve, an exhaust valve, and a valve operating mechanism that operates each valve (not shown).

  A water jacket 3j is formed in the cylinder head 3 to circulate the cooling water flowing in from the cylinder block 2, and the cylinder head 3 is cooled by the cooling water that circulates in the water jacket 3j in the direction indicated by the dashed arrow w. Is done.

Further, the left side wall of the cylinder head 3 is formed with a discharge port 3h through which the cooling water flowing through the water jacket 3j is discharged toward the radiator device.
Here, front and rear, left and right, and up and down directions represent directions viewed from the driver's seat of the vehicle on which the internal combustion engine 1 is mounted, and are indicated by arrows in each drawing.

  The EGR device 4 includes an EGR cooler 40, an EGR valve 41, a downstream EGR pipe 42, and a gasket 43. The EGR device 4 introduces exhaust gas flowing through the exhaust manifold 6 and cools it with the EGR cooler 40. The cooled exhaust gas is supplied into the intake manifold 7 through the EGR valve 41 and the downstream EGR pipe 42, and is supplied into a combustion chamber (not shown).

  Part of the exhaust gas exhausted from the combustion chamber returns to the combustion chamber again and recirculates. By recirculating the exhaust gas, a control device (not shown) controls the combustion temperature of the air-fuel mixture in the combustion chamber, reducing nitrogen oxides and pumping loss generated by combustion, and generating knocking and pre-ignition Suppress.

  In addition, when the exhaust gas is taken into the combustion chamber together with the intake air, the load of the piston is lowered while the fuel injection amount is kept small, and the temperature rise of the air-fuel mixture is moderated, thereby preventing abnormal combustion. The fuel consumption is improved.

  The EGR cooler 40 includes a cooling water circulation part 51, an upstream EGR pipe 52, a support ring 53, a gasket 54, and a pair of bolts 55 that fix the upstream EGR pipe 52 to the cylinder head 3. The

The EGR cooler 40 cools the exhaust gas by exchanging heat between the high-temperature exhaust gas flowing in the upstream EGR pipe 52 and the low-temperature cooling water flowing in the cooling water circulation portion 51, thereby reducing the downstream EGR. Supply to pipe 42.
A part of the cylinder head 3 corresponds to the housing of the present invention, and the upstream EGR pipe 52 corresponds to the exhaust gas distribution pipe of the present invention.

  As shown in FIG. 1, the cooling water circulation part 51 constitutes a part of the cylinder head 3 and has a cooling water circulation chamber 61 formed in the cylinder head 3. As shown in FIG. 3, the coolant circulation part 51 includes a front peripheral wall 62, a rear peripheral wall 63, and an annular peripheral wall 64 that surrounds the coolant circulation chamber 61 between the front peripheral wall 62 and the rear peripheral wall 63. Each of these peripheral walls is an integral part, and consists of a part of the cylinder head 3.

An insertion hole 62 a for inserting the upstream EGR pipe 52 into the cooling water circulation chamber 61 is formed in the front peripheral wall 62 so as to penetrate the outside of the cylinder head 3 and the cooling water circulation chamber 61.
Further, a pair of screw holes 62n are formed in the front peripheral wall 62 in the vicinity of the insertion hole 62a with a predetermined depth from the front wall surface of the cylinder head 3 with the insertion hole 62a interposed therebetween.

  An annular through hole 63 a that holds the support ring 53 is formed in the rear peripheral wall 63 so as to penetrate from the wall surface of the rear peripheral wall 63 on the cooling water circulation chamber 61 side to the outer wall surface of the rear peripheral wall 63. Yes.

  The through hole 63 a is formed with a gas discharge port communicating with a gas discharge passage (not shown) formed in the cylinder head 3 so as to discharge the exhaust gas to the outside of the cylinder head 3. The gas discharge passage communicates with an exhaust gas inlet (not shown) of the EGR valve 41, and the exhaust gas cooled in the upstream EGR pipe 52 flows into the EGR valve 41 through the gas discharge passage. Is done.

  The annular peripheral wall 64 is formed with a cooling water inflow passage 64 a that allows the water jacket 3 j and the cooling water circulation chamber 61 to communicate with each other on the upstream side of the exhaust gas and allows the cooling water in the water jacket 3 j to flow into the cooling water circulation chamber 61. Has been. The annular peripheral wall 64 is formed with a cooling water discharge passage 64b for discharging the cooling water in the cooling water circulation chamber 61 on the downstream side of the exhaust gas so as to communicate with the discharge port 3h of the cylinder head 3.

Note that the circumferential positions of the cooling water inflow passage 64a and the cooling water discharge passage 64b in the annular peripheral wall 64 shown in FIG. 3 are positions for convenience of explanation of the respective passages. The cooling water discharge passage 64b is formed at the optimal position connected to the jacket 3j and the optimal position connected to the discharge port 3h.

  The cooling water inflow passage 64a is formed on the upstream side of the exhaust gas in order to effectively cool the relatively high temperature upstream exhaust gas, and the cooling water discharge passage 64b is provided in the exhaust gas. The reason for this is that the cooling water is sufficiently circulated from the upstream side to the downstream side in the cooling water circulation chamber 61.

  In the cooling water circulation part 51, the cooling water flowing through the water jacket 3 j flows into the cooling water circulation chamber 61 from the cooling water inflow passage 64 a of the annular peripheral wall 64, and the cooling water flowing through the cooling water circulation chamber 61 is The water is discharged from the cooling water discharge passage 64b of the annular peripheral wall 64.

The upstream EGR pipe 52 includes a main body pipe 71 and a flange 72.
The main body pipe 71 is formed of a bent cylinder opened at both ends, connected to the exhaust manifold 6, an introduction portion 71b for introducing exhaust gas, a fixing portion 71c to which the flange 72 is fixed, a cooling unit It has a cooling part 71d inserted into the water circulation chamber 61 and cooled, and a mounting part 71e to which the support ring 53 is mounted.

  The introduction part 71b is composed of a pair of pipes divided in two between the connection part 71a and the flange 72, and is connected to each other by a flange 71f provided at the end of each pipe. Since the introduction part 71b is divided into two and connected by the flange 71f, the degree of freedom in assembling the exhaust manifold 6 and the upstream EGR pipe 52 is increased.

  The mounting portion 71e is formed to be annularly recessed from the circumferential surface so that the support ring 53 is mounted in the vicinity of the downstream end portion of the exhaust gas in the upstream EGR pipe 52. The recess of the mounting portion 71e is held when the support ring 53 is mounted, and movement of the support ring 53 in the axial direction with respect to the upstream EGR pipe 52 is restricted.

  The mounting portion 71e is formed in the vicinity of the downstream end. In the vicinity of the downstream end, the exhaust gas flowing into the upstream EGR pipe 52 is cooled by the cooling water and becomes relatively low in temperature. This is because the durability of the attached support ring 53 is improved.

  The flange 72 is formed in the outer periphery of the upstream EGR pipe 52 so as to fix the upstream EGR pipe 52 to the front peripheral wall 62 of the cylinder head 3, and a pair of through holes 72 a through which the bolts 55 are passed.

  The support ring 53 is made of, for example, an elastic elastic ring body formed in an annular shape, such as an O-ring. The support ring 53 is fitted into the mounting portion 71e to form the mounting portion 71e and the inner wall of the cylinder head 3 that forms the through hole 63a. Intervene between. The support ring 53 supports the upstream EGR pipe 52 on the cylinder head 3. The support ring 53 has a function of sealing the cooling water in the cooling water circulation chamber 61 and a function of absorbing expansion and contraction of the upstream EGR pipe 52 with respect to the cylinder head 3.

  The gasket 54 is sandwiched between the flange 72 and the front peripheral wall 62 of the cylinder head 3, and is fixed to the front side surface portion 3 m of the cylinder head 3 by the bolt 55 together with the flange 72. The gasket 54 has a function of sealing the cooling water in the cooling water circulation chamber 61 and a function of preventing foreign matter from entering from the outside of the cylinder head 3.

  As shown in FIG. 3, the EGR valve 41 includes a valve housing 81, a valve body 82, and a drive mechanism 83 that drives the valve body 82.

  The valve housing 81 is attached to the rear peripheral wall 63 of the cooling water circulation part 51 on one side surface, opens to one side surface, and communicates with the exhaust gas inlet passage 81a communicating with the through hole 63a, and on the side surface opposite to the one side surface. And an exhaust gas outlet passage 81b that opens. The valve housing 81 includes a communication passage 81c that communicates the exhaust gas inlet passage 81a and the exhaust gas outlet passage 81b, and a valve seat 81d that is formed at the boundary between the communication passage 81c and the exhaust gas inlet passage 81a. doing.

  The valve body 82 is connected to the umbrella portion 82a, which is connected to the umbrella portion 82a and the umbrella portion 82a, which is closed when the seat 82d is seated on the valve seat 81d and is opened when the communication passage 81c is separated from the valve seat 81d. And a rod portion 82b driven by the device 83.

  The drive mechanism 83 engages with a return spring (not shown) that urges the rod portion 82b to close the valve seat 81d and a rod portion 82b, and a rod that opens the umbrella portion 82a with a step motor (not shown). And a drive unit (not shown) for moving the part 82b. The drive mechanism 83 is not limited to the step motor described above, and may be a drive source having another structure. For example, a structure including a diaphragm and a drive actuator that moves the rod portion 82b by negative pressure may be used.

  By controlling the opening degree of the valve body of the EGR valve 41, the flow rate of the exhaust gas introduced from the exhaust manifold 6 is adjusted, and an appropriate amount of the exhaust gas according to the operating state of the internal combustion engine 1 is adjusted to the downstream EGR pipe 42. And is supplied to the intake manifold 7.

As shown in FIG. 1, the downstream EGR pipe 42 is formed of a bent cylinder opened at both ends and connected to the EGR valve 41 and the intake manifold 7, similarly to the upstream EGR pipe 52. Connecting portion 42b.
The downstream EGR pipe 42 recirculates the exhaust gas discharged from the EGR valve 41 into the intake manifold 7.

  The gasket 43 is sandwiched between the EGR valve 41 and the rear peripheral wall 63 of the cylinder head 3 and is fixed to the rear peripheral wall 63 of the cylinder head 3 by a bolt (not shown) together with the valve housing 81. The gasket 43 has a through hole, has a function of sealing the exhaust gas flowing through the through hole 63a and the exhaust gas inlet passage 81a, and a function of preventing foreign matter from entering from the outside of the cylinder head 3. .

As shown in FIGS. 1 and 2, the cylinder head cover 5 is configured by a cover that covers an upper opening (not shown) of the cylinder head 3 and is fixed to the cylinder head 3.

  The exhaust manifold 6 is attached to the front side surface portion 3 m of the cylinder head 3 and is connected to each exhaust port (not shown) formed in the cylinder head 3. The exhaust manifold 6 has four manifolds 6t through which exhaust gas exhausted from the exhaust port passes, and a collecting pipe 6s that collects the manifolds 6t and connects to the exhaust gas purification device 8 on the downstream side. An upstream EGR pipe 52 is connected to the collecting pipe 6s. Exhaust passages (not shown) are formed in the manifold 6t and the collecting pipe 6s, respectively.

  The intake manifold 7 is attached to the rear side wall portion 3u of the cylinder head 3, and includes four manifolds 7t that introduce air into the intake port, and a collecting pipe that collects the manifolds 7t and connects them to the upstream intake pipe. 7s. A downstream EGR pipe 42 is connected to the collecting pipe 7s. An intake passage (not shown) is formed in each of the manifold 7t and the collecting pipe 7s.

  The exhaust gas purification device 8 is disposed in the vicinity of the downstream side of the exhaust manifold 6 and reduces air pollutants such as hydrocarbons, carbon monoxide, and nitrogen oxides contained in the exhaust gas flowing from the exhaust manifold 6. It consists of a device that discharges the purified exhaust gas downstream, and is composed of, for example, a catalytic converter.

Next, the operation of the EGR device 4 of this embodiment will be briefly described.
When the internal combustion engine 1 shown in FIG. 1 is started, exhaust gas is exhausted from the combustion chamber in the cylinder head 3. The exhaust gas passes through the exhaust passage of the exhaust manifold 6 and is purified by the exhaust gas purification device 8. The purified exhaust gas is discharged to the atmosphere through a silencer (not shown).

  The EGR valve 41 of the EGR device 4 is opened by a control device (not shown) according to the operation status of the internal combustion engine 1. When the EGR valve 41 is opened, as shown by an arrow g in FIG. 1, exhaust gas is introduced from the introduction portion 71b of the upstream EGR pipe 52 of the EGR cooler 40, passes through the cooling portion 71d, and the downstream of the EGR valve 41. The side EGR pipe 42 is circulated in order and supplied to the intake passage of the intake manifold 7. The supplied exhaust gas recirculates into the combustion chamber in the cylinder head 3.

  When the exhaust gas passes through the cooling part 71d in the EGR cooler 40, heat is exchanged with the cooling water flowing through the cooling water circulation chamber 61 of the cooling water circulation part 51, and the temperature is lowered. As shown by an arrow w in FIG. 1, this cooling water circulates in the cylinder block 2 from a radiator (not shown), then circulates in the water jacket 3 j of the cylinder head 3, and enters the cooling water inflow passage of the cooling water circulation portion 51. It flows into the cooling water circulation chamber 61 from 64a.

  The cooling water that has flowed through the cooling water circulation chamber 61 is discharged from the cooling water discharge passage 64b, discharged from the discharge port 3h of the cylinder head 3, and returned to the radiator.

  Since the exhaust gas is cooled by the EGR cooler 40, the problem that occurs when mixed with the intake air is solved. That is, when exhaust gas having a high temperature is mixed with intake air, there is a problem that the temperature of the air-fuel mixture rises, the intake density is lowered, and the charging efficiency is lowered. By cooling the exhaust gas with the EGR cooler 40, such a problem is solved.

  According to the EGR cooler 40 of the present embodiment having the above configuration, the upstream EGR pipe 52 includes the flange 72 that is fixed to the front side surface portion 3m of the cylinder head 3 and the mounting portion 71e that mounts the support ring 53. Since it is comprised by a simple structure, the manufacturing process of the EGR cooler 40 can be reduced compared with the conventional one.

  Further, according to the EGR cooler 40 of the present embodiment, the upstream side EGR pipe 52 is inserted into the insertion hole 62a of the cooling water circulation portion 51 with the support ring 53 attached to the attachment portion 71e and the support ring 53 attached. The upstream EGR pipe 52 is assembled by simply inserting and setting the support ring 53 in the through hole 63a and fixing the flange 72 to the front side surface portion 3m.

  As a result, the assembly process of the EGR cooler 40 is reduced as compared with the conventional one, and the upstream EGR pipe 52 can be easily assembled to the cooling water circulation part 51 of the cylinder head 3.

  Further, according to the EGR cooler 40 of the present embodiment, the downstream end portion of the upstream EGR pipe 52 becomes a free end, and the support ring 53 absorbs expansion and contraction of the upstream EGR pipe 52 with respect to the cylinder head 3. The thermal stress is not generated in the upstream EGR pipe 52, and the upstream EGR pipe 52 is not damaged by the thermal stress. As a result, the durability of the EGR cooler 40 can be improved.

  According to the EGR cooler 40 of the present embodiment, the cooling water circulation part 51 is constituted by a part of the cylinder head 3, and the cooling water is constituted by cooling water for cooling the internal combustion engine 1. In addition, the cooling water circulation part 51 is not provided separately from the cylinder head 3. As a result, the EGR cooler 40 does not protrude from the cylinder head 3, and space saving of the internal combustion engine is achieved.

  Further, according to the EGR cooler 40 of the present embodiment, the cooling water circulation part 51 is not manufactured separately from the cylinder head 3, so that manufacturing processes such as component manufacturing and assembly are reduced compared to the conventional one. Less. Moreover, since the cooling water circulation part 51 is comprised by a part of cylinder head, the piping which distribute | circulates the cooling water which cools the internal combustion engine 1 to the cooling water circulation part 51 decreases, and manufacturing processes, such as parts manufacture and assembly | attachment, etc. Can be reduced.

  In addition, although the EGR cooler 40 in this embodiment demonstrated the case where the upstream EGR pipe 52 as an exhaust gas distribution pipe was comprised from the introducing | transducing part 71b to the cooling part 71d shown in FIG. You may comprise the exhaust-gas distribution pipe of the EGR cooler of invention with structures other than a single structure.

  For example, as shown in FIG. 4, an exhaust gas distribution pipe is constituted by an upstream EGR pipe 80 having a structure in which two pipes, that is, an introduction pipe 81 for introducing exhaust gas and a cooling pipe 82 for cooling exhaust gas are connected. You may do it.

  The introduction pipe 81 has a main body pipe 91 and a flange 92 as a flange portion fixed to the downstream end portion of the main body pipe 91. The main body pipe 91 has a connecting portion 91 a that is connected to the collecting pipe 6 s of the exhaust manifold 6, and an introducing portion 91 b that introduces exhaust gas from the collecting pipe 6 s of the exhaust manifold 6 and distributes it into the cooling pipe 82. . A pair of through holes 92 a are formed in the flange 92 with the main body pipe 91 interposed therebetween.

  The cooling pipe 82 has a main body pipe 95 and a flange 96 as a connecting flange portion fixed to the upstream end of the main body pipe 95. The main body pipe 95 has a connecting portion 95 a that connects to the main body pipe 91 of the introduction pipe 81, a cooling portion 95 b that cools the introduced exhaust gas, and a mounting portion 95 c that mounts the support ring 53. A pair of through holes 96 a are formed in the flange 96 with the main body pipe 91 interposed therebetween.

  The main body pipe 95 is inserted into the insertion hole 62a of the front peripheral wall 62 and supported by the through hole 63a of the rear peripheral wall 63 with the support ring 53 mounted on the mounting portion 95c of the main body pipe 95 and the gasket 54 passed through. The ring 53 is fitted. The flange 96 of the introduction pipe 81 is brought into contact with the flange 96 of the cooling pipe 82 and the gasket 54 interposed therebetween, and the bolt 55 is inserted into the through hole 92a and the through hole 96a. The cooling pipe 82 is fixed to the cylinder head 3 by fastening.

  According to the upstream EGR pipe 80 having a structure of connecting two pipes, the flange 96 of the cooling pipe 82 is connected to the flange 92 of the introduction pipe 81, so that the introduction pipe 81 located outside the cylinder head 3 is deformed. The cooling pipe 82 located inside the cylinder head 3 is not affected. As a result, the deformation amount of the cooling pipe 82 is reduced, and stress due to the deformation of the introduction pipe 81 does not occur in the cooling pipe 82, so that the sealing performance of the EGR cooler 40 is maintained and the durability is improved.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 3 ... Cylinder head, 40 ... EGR cooler, 51 ... Cooling water distribution part (housing), 52, 80 ... Upstream EGR pipe (exhaust gas distribution pipe), 53 ... Support ring, 62 ... Front peripheral wall ( Housing), 62a ... insertion hole, 63 ... rear peripheral wall (housing), 63a ... through hole, 64 ... annular peripheral wall (housing), 71, 95 ... main body pipe (exhaust gas distribution pipe), 71e, 95c ... mounting portion, 72, 96 ... flange (flange), 92 ... flange (connection flange)

Claims (3)

An EGR cooler for cooling exhaust gas recirculated from an exhaust passage of an internal combustion engine to an intake passage,
A housing having a cooling water circulation part for circulating cooling water;
An exhaust gas circulation pipe for circulating the exhaust gas from the upstream side to the downstream side in the cooling water circulation part;
A support ring provided between the housing and the exhaust gas circulation pipe, and supporting the exhaust gas circulation pipe to the housing;
The housing has an insertion hole formed on the upstream side so that the exhaust gas circulation pipe is inserted into the cooling water circulation part, and a through hole formed on the downstream side so as to hold the support ring. ,
The exhaust gas distribution pipe has a flange portion fixed to the outside of the housing on the upstream side, and a mounting portion for mounting the support ring on the downstream side,
An EGR cooler, wherein heat is exchanged between the cooling water flowing in the cooling water flow portion and the exhaust gas flowing in the exhaust gas distribution pipe.   The flange portion of the exhaust gas circulation pipe is connected to a connection flange portion provided at an end portion of the exhaust pipe for circulating the exhaust gas on a side surface opposite to the side surface in contact with the housing. The EGR cooler according to claim 1.   3. The EGR cooler according to claim 1, wherein the housing includes a part of a cylinder head constituting the internal combustion engine, and the cooling water is cooling water for cooling the internal combustion engine. 4. .

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