JP3240795B2 - EGR gas cooling structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an engine,
The present invention relates to an exhaust gas recirculation (EGR) device for recirculating a part of the exhaust gas to an intake air-fuel mixture, and more particularly to a cooling structure for cooling the EGR gas.

[0002]

2. Description of the Related Art Conventionally, it is known that an engine is provided with an exhaust gas recirculation (EGR) device for the purpose of reducing nitrogen oxides (NOx) in exhaust gas.
The EGR device is configured to recirculate a part of the exhaust gas as an EGR gas to the air-fuel mixture sucked into the combustion chamber. That is, it has an EGR passage that connects between the exhaust manifold and the intake manifold, and an EGR valve provided in the EGR passage. The ratio of the EGR gas to the intake air-fuel mixture is adjusted by appropriately controlling the opening of the EGR valve according to the operating state of the engine.

Here, since the EGR gas is taken into the combustion chamber together with the air-fuel mixture, it must be maintained at an appropriate temperature. That is, although the EGR gas is originally at a high temperature, its EG
If the temperature of the R gas is too high, the air-fuel mixture is heated and thermally expanded, thereby lowering the air filling efficiency. As a result, there is a possibility that the combustion rate of the air-fuel mixture is deteriorated and the output of the engine is reduced. On the other hand, if the temperature of the EGR gas is too low, the viscosity of the substance such as tar in the gas increases, and the substance easily adheres to the EGR passage and the EGR valve,
The reliability of the device may be reduced.

Accordingly, a technique aimed at addressing the above-mentioned disadvantages and the like is disclosed in Japanese Utility Model Laid-Open Publication No. Sho 61-179361. In this prior art, a water flow passage is formed in the wall of the intake manifold, adjacent to the air-fuel mixture passage, for passing cooling water of the engine. In addition, a part of the EGR passage is formed integrally with the wall adjacent to the water flow passage. Cooling water after cooling each part of the engine body passes through the water flow path, and after the engine warms up, the cooling water that has warmed to some extent passes through the water flow path, thereby heating the mixture passing through the mixture path. And its vaporization is promoted. In addition, when the cooling water passes through the water flow path, the EG
The EGR gas passing through the R passage is kept at an appropriate temperature.

[0005]

However, in the prior art, in order to achieve both heating of the air-fuel mixture and cooling of the EGR gas, both the water flow passage and a part of the EGR passage are formed in the wall of the intake manifold. ing. Therefore, EG
Although the high-temperature EGR gas passing through the R passage is cooled by the cooling water in the water flow path, part of the heat of the ERG gas is transmitted to the wall itself of the intake manifold. As a result, in the air-fuel mixture passage adjacent to the EGR passage, the air-fuel mixture passing through the passage is heated more than necessary, and there is a possibility that engine performance may be reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the invention is to provide an engine having an EGR passage, in which EGR gas is effectively cooled by engine cooling water, and exchange during EGR gas cooling is performed. It is an object of the present invention to provide an EGR gas cooling structure capable of effectively utilizing heat without adversely affecting an intake air-fuel mixture to further improve heater performance.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, an air-fuel mixture sucked from an intake passage is burned and exhaust gas after the combustion is exhausted. An EGR passage connected between the intake passage and the exhaust passage for recirculating a part of the exhaust gas discharged from the engine to the exhaust passage as EGR gas to the intake passage; An EGR valve provided in the EGR passage for adjusting the amount of EGR gas passing through the EGR passage; a cooling water passage for circulating cooling water for cooling each part of the engine; A heater water passage for circulating a portion of the cooling water connected and circulating through the passage to a heater heat exchanger disposed at a location requiring heating; and a heater water passage formed in the engine.
Externally attached to the outlet of the cooling water passage, a part of the cooling water is
A pipe joint for branching to a heater water passage,
The cooling water in the heater water passage branched from the cooling water passage
In order to further cool the EGR gas,
Part of the heater water passage and part of the EGR passage
Are formed integrally, and the pipe joint is provided separately from the intake passage.

[0008]

[0009] In the second invention described in claim 2 is the configuration of the first invention, the EGR passage formed in the conduit fitting, purport that it has a shape meandering in the longitudinal direction.

[0010]

According to the structure of the first aspect of the invention, the air-fuel mixture sucked into the engine from the intake passage is burned, so that high-temperature exhaust gas is discharged to the exhaust passage. At this time, EGR
When the valve is opened, a part of the high-temperature exhaust gas discharged to the exhaust passage is recirculated as EGR gas to the intake passage through the EGR passage.

On the other hand, each part of the engine is cooled by cooling water circulating in a cooling water passage. A part of the cooling water that cools and warms each part of the engine and circulates in the cooling water passage is circulated to the heater heat exchanger through the heater water passage, and the heat exchange in the heat exchanger requires heating. Is heated appropriately. Also, the cooling formed in the engine
Cooling water is provided by a pipe joint external to the outlet of the water passage.
A part is branched to a heater water passage.

Here, for a heater branched from a cooling water passage.
In order to cool the EGR gas with the cooling water in the water passage,
Part of the heater water passage and part of the EGR passage inside the joint
Since the bets are integrally formed, the high-temperature EGR gas through the EGR passage is cooled appropriately by only the cooling water passing through the heater water passage branched from the cooling water passage. or,
Since the cooling water after cooling the EGR gas is circulated to the heat exchanger for the heater, the heat deprived from the EGR gas is exchanged by the heat exchanger. Further, a pipe joint in which a part of the EGR passage and a part of the heater water passage are integrally formed is provided separately from the intake passage. Therefore , heat of the EGR gas passing through the EGR passage is not transmitted to the air-fuel mixture before being mixed with the EGR gas. As a result, the mixture becomes E
It is not inadvertently heated by the GR gas, and the engine performance is not degraded. Furthermore, one of the cooling water passages
Part, part of the heater water passage and part of the EGR passage
And are formed integrally with the two pipe joints. As a result, cooling water
Route, heater water passage and EGR passage
Compactness can be achieved by the pipe joint.

[0013]

[0014]

According to the structure of the second invention, in addition to the operation of the first invention, since the EGR passage is meandering in the vertical direction at the pipe joint, the effective length of the EGR passage at the pipe joint is increased. And the EGR passage can be made longer adjacent to the heater water passage.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the EGR gas cooling structure in the first and second aspects of the present invention is embodied in a V-type gasoline engine of an automobile will be described in detail with reference to FIGS.

FIG. 1 is a schematic diagram showing a cooling device and an exhaust gas recirculation (EGR) device in a V-type engine 1.
FIG. 2 is a perspective view schematically showing a cooling device in the engine 1.

The engine 1 includes a pair of left and right banks 4A and 4B each including a cylinder block 2 and a cylinder head 3. A plurality of cylinder bores 5 forming a combustion chamber are formed in the cylinder block 2. The engine 1 is provided with an intake manifold 6 and a surge tank 7 forming an intake passage, and an exhaust manifold 8 forming an exhaust passage. The intake manifold 6 is provided with an injector (not shown) for fuel injection. A throttle body 9 having a throttle valve 9a is provided near the surge tank 7. An idle speed control valve (ISC valve) 10 is provided near the throttle body 9 for adjusting the amount of intake air passing through the intake passage when the throttle valve 9a is fully closed, that is, when the engine 1 is idling. And
A mixture of air passing through the intake manifold 6 and fuel injected from the injector is burned in the combustion chamber, and the exhaust gas after the combustion is discharged through the exhaust manifold 8 and the like.

The EGR device is provided with EGR pipes 12A and 12B constituting an EGR passage 11, and an EGR valve 13. The EGR pipes 12A and 12B are disposed between the intake manifold 6 and the exhaust manifold 8, and use a part of exhaust gas discharged from a combustion chamber (not shown) of the engine 1 to the exhaust manifold 8 as EGR gas.
It is recirculated to the intake manifold 6. EGR valve 13 is E
The opening is adjusted in the middle of the GR passage 11 to adjust the amount of EGR gas passing through the passage 11. As described above, by appropriately adjusting the amount of the EGR gas recirculated to the intake manifold 6, the combustion of the air-fuel mixture in the combustion chamber is improved, and the nitrogen oxides (N
Ox) is reduced.

The cooling device is configured as follows.
The cylinder block 2 and the cylinder head 3 of each of the left and right banks 4A, 4B are provided with a plurality of water jackets 14 and the like which form a cooling water passage and communicate with each other.
On the front side of the cylinder block 2, a water pump 15 driven in conjunction with the engine 1 is provided. On both front and rear sides of the cylinder block 2, a front water joint 16 and a rear water joint 17 as pipe joints are provided, respectively. These joints 16 and 17 are conventionally used as components of a cooling device in a V-type engine.

Cooling water is introduced into the front water joint 16 through the cooling water passages of the left and right banks 4A, 4B. The cooling water introduced into the joint 16 is introduced into a radiator 19 through a first pipe 18 and is introduced into a water inlet 21 through a second pipe 20. The cooling water introduced into the radiator 19 is subjected to heat exchange (radiation) there, and then the third pipe 2
2 returns to the water inlet 21. Furthermore,
The cooling water returned to the water inlet 21 is introduced into the water pump 15. The water inlet 21 has a built-in thermostat 21a. The thermostat 21a expands and contracts according to the temperature state of the cooling water, so that the amount of the cooling water returned to the water inlet 21 through the third pipe 22 is adjusted. . The cooling water overflowing from the radiator 19 is introduced into a reserve tank 24 through a fourth pipe 23, and the reserve tank 2
The cooling water overflowing from 4 is returned to the water pump 15 through the fifth pipe 25 and the like.

On the other hand, the rear water joint 17 also has
Cooling water is introduced through the cooling water passages of the left and right banks 4A, 4B. A part of the cooling water introduced into the joint 17 is supplied to a heater pipe 26 forming a heater water passage.
Through the heater core 27 as a heat exchanger for the heater. The heater core 27 is provided facing a vehicle room that needs to be heated (heated), and a part of the cooling water that has been cooled by cooling each part of the engine 1 is introduced and radiated. The cooling water introduced into the heater core 27 and radiated therefrom passes through the water return pipe 28 through the heater return pipe 28.
Returned to 5. A part of the cooling water introduced into the rear water joint 17 is sent to the throttle body 9 and the ISC valve 10 through the sixth pipe 29. Further, a part of the cooling water introduced into the rear water joint 17 passes through the seventh pipe 30 to the EGR valve 13 and the ISC
It is sent to the valve 10. In other words, rear water joint 1
At 7, the cooling water passages of the left and right banks 4A, 4B are gathered, and the gathered cooling water passages are branched to the heater pipe 26 and the pipes 29, 30.

The throttle body 9, EGR valve 13 and I
The cooling water sent to the SC valve 10 is returned to the water pump 15 from the ISC valve 10 through the eighth pipe 31 and the water inlet 21 after warming those walls.
Then, the cooling water returned from each part to the water pump 15 is sent again to each cooling water passage of each of the left and right banks 4A and 4B, and is recirculated through the above-described paths.

FIGS. 3 and 4 show the rear water joint 17, pipes 26, 29, 30 and members 7, 9, 1 respectively.
The arrangement state of 0, 13, etc. is shown. The throttle body 9, the ISC valve 10 and the EGR valve 13 are arranged in front and left and right of the surge tank 7. The above-mentioned sixth pipe 29 is disposed between the rear water joint 17 and the throttle body 9 and between the throttle body 9 and the ISC valve 10. The above-described seventh pipes 30 are disposed between the rear water joint 17 and the EGR valve 13 and between the EGR valve 13 and the ISC valve 10, respectively.

In this embodiment, in order to cool the high-temperature EGR gas passing through the EGR passage 11, the EGR passage 11
Is provided adjacent to the heater water passage. Specifically, in this embodiment, the rear water joint 17
Is used as an EGR cooler, a part of the heater water passage is formed in the wall of the joint 17, and the wall has E
A part of the GR passage 11 is formed integrally.

FIG. 5 shows the rear water joint 17.
6 is a plan view of the joint 17, and FIGS. 7 to 12 are cross-sectional views of FIG. As shown in FIGS. 3 to 12, in this embodiment, a water passage portion 32 connected to the heater pipe 26 and constituting a part of the heater water passage is formed in the wall of the rear water joint 17. . In addition, an EGR passage portion 33 constituting a part of the EGR passage 11 is provided on a wall of the joint 17.
Are integrally formed. The EGR passage 33 has a horizontal U-shape meandering in the vertical direction. The lower end of the EGR passage 33 is connected to the exhaust manifold 8 by an EGR pipe 12A. The upper end of the EGR passage portion 33 is connected to the EGR valve 1 by the EGR pipe 12B.
3 is connected.

As shown in FIGS. 5 to 12, the water passage portion 32 of the rear water joint 17 is divided into an upper passage portion 35 and a lower passage portion 36 by a partition wall 34. At the center in the horizontal direction of the partition wall 34, upper and lower passage portions 35,
A communication hole 37 that allows communication between the communication holes 36 is formed. Above one end (the left end in FIG. 5) of the rear water joint 17, a pipe joint 38 projecting upward is provided. The pipe joint 38 communicates with the upper passage 35, and one end of the seventh pipe 30 is connected to the joint 38. A flange 39 is formed below the left end of the rear water joint 17. This flange 39
One end of the lower passage portion 36 is opened, and the flange 39 is connected to the cooling water passage of the right bank 4B.

On the other hand, two large and small pipe joints 40 and 41 projecting upward are provided above the other end (the right end in FIG. 5) of the rear water joint 17. Each of the pipe joints 40 and 41 communicates with the upper passage portion 35. One end of the heater pipe 26 is connected to the larger pipe joint 40, and one end of the sixth pipe 29 is connected to the smaller pipe joint 41. A flange 42 is formed below the right end of the rear water joint 17. This flange 42
The other end of the lower passage portion 36 is opened, and the flange 42 is connected to the cooling water passage of the left bank 4A. Here, among the pipe joints 38, 40, 41, the inner diameter of the pipe joint 40 for the heater pipe 26 is set to be the largest. Therefore, the largest amount of cooling water flows from the rear water joint 17 to the heater core 27.

The EGR passage portion 33 meandering in the vertical direction at the rear water joint 17 has a shape in which a portion other than the curved portion is inclined downward at a certain angle θ. Further, flanges 43 and 44 are formed at both upper and lower ends of the EGR passage portion 33, respectively. The upper end flange 43 is connected to the EGR pipe 12B, and the lower end flange 44 is connected to the EGR pipe 12A.

Next, the operation of the EGR gas cooling structure configured as described above will be described. Now, when the EGR valve 13 is opened while the engine 1 is operating, a part of the high-temperature exhaust gas discharged from the combustion chamber to the exhaust manifold 8
The R gas is recirculated to the intake manifold 8 through the EGR passage 11 and is taken into the combustion chamber together with the air-fuel mixture. At this time, the EGR gas is supplied to the rear water joint 1
7 through the EGR passage section 33.

On the other hand, during operation of the engine 1, each part of the engine 1 is cooled by cooling water circulating in a cooling water passage including the water jacket 14 and the like. Here, each part of the engine 1 is cooled and heated, and the left and right banks 4A,
Part of the cooling water circulating in the cooling water passage of 4B is introduced into the rear water joint 17. That is, the cooling water introduced into the rear water joint 17 from the left and right banks 4A, 4B first flows into the lower passage portion 36. The cooling water flowing into the lower passage portion 36 passes through the communication hole 37 and is
5 and is diverted to both ends of the upper passage portion 35. The cooling water diverted to both ends of the upper passage 35 flows through the pipes 30, 26, 29 to the EGR valve 13, the heater core 27, the throttle body 9, and the ISC valve 10, respectively.

Here, a part of the cooling water is supplied to the heater pipe 2.
When the heat is circulated through the heater core 27 through the heater 6, the portion that needs to be heated, that is, the vehicle interior, is appropriately heated by heat radiation from the heater core 27. A part of the cooling water is supplied to the sixth pipe 29
When the throttle body 9 is circulated through the throttle body 9, the wall of the throttle body 9 is appropriately warmed up, and icing of the throttle valve 9a can be prevented. When a part of the cooling water is circulated to the EGR valve 13 through the seventh pipe 30, the wall of the EGR valve 13 is appropriately warmed up.
For this reason, it is possible to secure a suitable operation response of the EGR valve 13 even in a cold state. Further, a part of the cooling water is supplied through the sixth and seventh pipes 29 and 30 to the ISC valve 10.
The wall of the ISC valve 10 is appropriately warmed up. Therefore, a suitable operation responsiveness of the ISC valve 10 can be ensured even in a cold state.

In the rear water joint 17, since the EGR passage 33 is formed adjacent to the water passage 32, the high temperature EG passing through the EGR passage 33 is formed.
The R gas is actively cooled by the cooling water passing through the water passage portion 32. That is, the EG using the cooling water of the engine 1
The R gas can be effectively cooled. Further, since the EGR gas can be cooled, the EGR gas is always kept at a suitable temperature. As a result, it is possible to prevent the air filling rate in the combustion chamber from deteriorating due to the temperature of the EGR gas being too high, and to prevent deposits such as tar from adhering to the EGR valve 13 and the like due to the temperature of the EGR gas being too low. be able to.

Most of the cooling water after cooling the high-temperature EGR gas flows to the heater core 27,
The heat of the cooling water, including the heat of exchange when the gas is cooled, is effectively radiated by the heater core 27. That is, a large amount of heat deprived from the EGR gas is added to the amount of heat deprived from each part of the engine 1, and most of the heat is effectively radiated by the heater core 27. As a result, the heat exchange in the cooling of the EGR gas is utilized, and the amount of heat radiation in the heater core 27 can be increased by the amount of the exchange heat, so that the heater performance can be further improved. For this reason, a large amount of heating heat can be efficiently secured, particularly in a vehicle compartment that needs active heating. Further, for the same reason as described above, the warm-up performance of the throttle body 9, the ISC valve 10, and the EGR valve 13 can also be improved.

Here, in the rear water joint 17, the cooling water introduced from the left and right banks 4 A, 4 B into the lower passage portion 36 is appropriately mixed in the communication hole 37, and then mixed to both ends of the upper passage portion 35. Is diverted. Therefore, even if a large amount of cooling water flows from the rear water joint 17 to the heater core 27, the balance of the cooling water circulation in each of the left and right banks 4A and 4B is not lost.

Further, the rear water joint 17 capable of balancing the circulation of the cooling water as described above is used as an EGR cooler. Therefore, unlike a case where an EGR passage is provided adjacent to a specific water jacket in a cylinder block or a cylinder head, the cooling water temperature locally rises in the cylinder block 2 or the cylinder head 3. In addition, it is possible to prevent the cooling balance in each part of the engine 1 from deteriorating.

Further, in this embodiment, the rear water joint 17 is provided separately from the intake passage such as the intake manifold 6. Therefore, the heat of the EGR gas passing through the EGR passage 33 at the rear water joint 17 is
It is not transmitted to the mixture before being mixed with the EGR gas. As a result, the air-fuel mixture is not carelessly heated by the EGR gas, and the performance of the engine 1 does not deteriorate.

Further, in this embodiment, a part of the cooling water passage, a part of the heater water passage, and a part of the EGR passage 11 are formed integrally with one rear water joint 17. Therefore, the layout of the cooling water passage, the heater water passage, and the EGR passage 11 can be compacted by one rear water joint 17. In particular, the rear side of the engine 1 is a narrow space between the dashboard and the dashboard for partitioning the vehicle compartment, and in many cases, piping for a brake or the like, a wire harness, and the like are intersected. Therefore, by narrowing the relationship between the passages into one rear water joint 17, the narrow space on the rear side of the engine 1 can be effectively used, and the heat damage to each peripheral component can be greatly reduced. Can also.

In addition, in the rear water joint 17 of this embodiment, since the EGR passage 33 is meandering in the vertical direction, the effective length of the EGR passage 33 is increased, and the EGR passage 33 is It becomes possible to make the water passage portion 32 be long adjacent to the water passage portion 32. As a result, the cooling performance of the rear water joint 17 for cooling the EGR gas can be improved. Further, since the meandering portion of the EGR passage portion 33 is inclined downward, the water condensed in the EGR passage portion 33 flows down along the inclination of the EGR passage portion 33, and the condensed water is condensed. There is no accumulation in the passage portion 33. Therefore, the inner wall of the EGR passage 33 can be prevented from being corroded by the condensed water.

In addition, in this embodiment, the rear water joint 17 is used as an EGR cooler, and an EGR passage portion 33 is formed integrally with a wall thereof. Therefore,
In a V-type engine that does not employ an EGR device, it can be dealt with simply by using another rear water joint having no EGR passage instead of the rear water joint 17.

It should be noted that the present invention is not limited to the above-described embodiment, and may be carried out as follows by appropriately changing a part of the configuration without departing from the spirit of the invention. (1) In the above-described embodiment, the heater heat exchanger provided at a location requiring heating is embodied as the heater core 27 for vehicle interior heating. It can be embodied as a panel heater or the like used for this purpose.

(2) In the above embodiment, the pipe joint is embodied as the rear water joint 17 for balancing the circulation of the cooling water in the left and right banks 4A, 4B of the V-type engine 1. On the other hand, in a serial type engine, a pipe joint externally provided at an outlet of cooling water formed in a cylinder block is provided, and the pipe joint is provided with a part of a heater water passage and a part of an EGR passage. May be integrally formed.

(3) In the above embodiment, the water passage portion 32 and the EGR passage portion 33 are formed integrally with the rear water joint 17, so that a portion of the heater water passage is connected to the EGR passage.
A part of the passage 11 was made adjacent. On the other hand, in the middle of the heater pipe constituting the heater water passage,
The GR passage may be adjacent.

(4) In the above embodiment, the EGR gas cooling structure is embodied in a V-type gasoline engine of an automobile.
The GR gas cooling structure may be embodied in a diesel engine.

(5) In the above embodiment, the partition wall 34 is provided inside the rear water joint 17, and the water passage section 32 is divided into an upper passage section 35 and a lower passage section 36 in upper and lower stages. The partition wall 34 in the joint 17 may be eliminated.

[0046]

As described above in detail, according to the first aspect, an EGR passage for recirculating a part of the exhaust gas of the engine as the EGR gas to the intake passage is provided, and the cooling for circulating the engine cooling water is provided. The water passage is connected to a heater water passage that circulates a part of the cooling water to a heater heat exchanger provided at a location requiring heating. Also formed on the engine
A pipe joint externally attached to the outlet of the cooling water passage
Part of the cooling water is branched into a heater water passage. And
EGR gas is generated by the cooling water in the branched heater water passage.
The so cooled, formed integrally with a portion of the part and <br/> heater water passage of the EGR passage inside the pipe joint, and DokanroTsugi
A hand is provided separately from the intake passage.

Accordingly, the high-temperature EGR gas passing through the EGR passage is appropriately cooled only by the cooling water passing through the heater water passage, and the heat deprived from the EGR gas is exchanged by the heat exchanger. Is heated as needed. As a result, the EGR gas can be effectively cooled by the engine cooling water, and the heat exchanged at the time of cooling the EGR gas can be effectively used without adversely affecting the intake air-fuel mixture to the engine, so that the heater performance of the heat exchanger can be improved. Of the present invention can be further improved. Furthermore, conduit joint formed integrally with a portion of the part and the heater water passage of the EGR passage, because it is provided separately from the intake passage, the heat of the EGR gas passing through the E GR passage, EGR It is not transmitted to the mixture before being mixed with the gas. As a result, the air-fuel mixture is not carelessly heated by the EGR gas, and the performance of the engine is not reduced.

[0048]

[0049] A part of the cooling water passage, a portion of the part and the EGR passage of the heater water passage is formed integrally with one of the pipe joint. As a result, there is an excellent effect that the layout of the cooling water passage, the heater water passage and the EGR passage can be compacted by one pipe joint.

According to the second aspect of the present invention, in the configuration of the first aspect , the EGR passage in the pipe joint has a shape meandering in the vertical direction. Accordingly, the effective length of the EGR passage is increased at the pipe joint, and the EGR passage can be made longer adjacent to the heater water passage. As a result, an excellent effect that the cooling performance of the EGR gas at the pipe joint can be improved is exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an engine cooling device and an EGR device according to an embodiment of the first and second aspects of the present invention;

FIG. 2 is a perspective view schematically showing a cooling device for a V-type engine in one embodiment.

FIG. 3 illustrates, in one embodiment, a rear water joint,
It is a top view which shows the arrangement state centering on the surge tank of each pipe and each member.

FIG. 4 illustrates a rear water joint according to one embodiment;
It is a front view on the rear side showing an arrangement state centering on a surge tank of each pipe and each member.

FIG. 5 is a front view showing a rear water joint in one embodiment.

FIG. 6 is a plan view showing a rear water joint in one embodiment.

FIG. 7 is a sectional view taken along line AA of FIG. 5 in one embodiment.

FIG. 8 is a sectional view taken along line BB of FIG. 5 in one embodiment.

FIG. 9 is a cross-sectional view taken along line CC of FIG. 5 in one embodiment.

FIG. 10 is a sectional view taken along line DD of FIG. 5 in one embodiment.

11 is a sectional view taken along line EE of FIG. 5 in one embodiment.

FIG. 12 is a sectional view taken along line FF of FIG. 5 in one embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 6 ... Intake manifold, 7 ... Surge tank (6, 7 etc. comprise an intake passage), 8 ... Exhaust manifold, 11 ... EGR passage, 13 ... EGR valve, 17
... a rear water joint as a pipe joint, 26 ... a heater pipe constituting a heater water passage, 27 ... a heater core as a heat exchanger, 32 ... a water passage portion constituting a part of a cooling water passage, 33 ... an EGR passage EG that forms part of
R passage section.

Claims (2)

(57) [Claims] An engine configured to burn an air-fuel mixture sucked through an intake passage and discharge exhaust gas after the combustion through an exhaust passage; and an engine connected between the intake passage and the exhaust passage, E for recirculating a part of exhaust gas discharged from the engine to the exhaust passage as EGR gas to the intake passage.
A GR passage, and the EG provided in the EGR passage and passing through the passage.
An EGR valve for adjusting the amount of R gas, a cooling water passage for circulating cooling water for cooling each part of the engine, and one of cooling water connected to the cooling water passage and circulating through the passage. A heater water passage for circulating the part through a heater heat exchanger disposed at a location requiring heating, and an external part at an outlet of the cooling water passage formed in the engine.
And a part of the cooling water is branched into the heater water passage.
A pipe joint for causing the cooling water in the heater water passage branched from the cooling water passage.
In order to further cool the EGR gas,
Part of the heater water passage and part of the EGR passage
And an EGR gas cooling structure wherein the pipe joint is formed separately from the intake passage. 2. The EGR gas cooling structure according to claim 1, wherein the EGR passage formed in the pipe joint extends vertically.
An EGR gas cooling structure having a meandering shape .