JPH1113554A - Egr gas cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR gas cooling device for cooling EGR gas recirculated from an exhaust system to an intake manifold through an EGR pipe passage, whose weight is remarkably reduced. SOLUTION: An EGR gas cooling device has an EGR pipe passage for recirculating exhaust gas to an intake system. EGR gas is flowed through an outer cylinder 21 in which a heat exchanger 41 prepared by arranging a plurality of pipes 37 and connecting their both ends by means of end plates 39, 39. The outer cylinder 21 is formed with a resin, and an inlet pipe 23 and an outlet pipe 25 for cooling water are arranged on an outer periphery of the outer cylinder 21. An exhaust opening end 21b and an intake opening end 21a of the outer cylinder 21 are connected to an exhaust side junction pipe 31 and an intake side junction pipe 29. An exhaust side end of the heat exchanger 41 is projected from the exhaust side opening end 21b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an EGR system for an exhaust system.
The present invention relates to an EGR gas cooling device for cooling EGR gas recirculated to an intake manifold via a pipe.

[0002]

2. Description of the Related Art Conventionally, in an engine, in order to reduce nitrogen oxides (NOx) in the exhaust gas, a part of the exhaust gas is taken out of an exhaust system and added to an air-fuel mixture.
(Exhaust Gas Recirculation). An EGR device for performing such EGR includes:
A part of the exhaust gas from the exhaust system is configured to be recirculated as an EGR gas to the air-fuel mixture sucked into the combustion chamber. For example, as shown in FIG. An EGR passage 3 connecting the intake manifold 2 and an EGR passage provided in the EGR passage 3
And a valve 4.

[0003] The ratio of the EGR gas to the intake air-fuel mixture is adjusted by appropriately controlling the opening of the EGR valve 4 according to the operating state of the engine. Such an E
In the GR device, since the EGR gas is taken into the combustion chamber together with the air-fuel mixture, it is necessary to maintain the temperature of the EGR gas at an appropriate temperature. In other words, the EGR gas is naturally high in temperature, but if the temperature of the EGR gas is too high, the air-fuel mixture is heated and thermally expanded, so that the air charging efficiency is deteriorated and the combustion rate of the air-fuel mixture is deteriorated. The output of the engine may be reduced.

On the other hand, if the temperature of the EGR gas is too low,
The viscosity of the adhering substance such as tar in the GR gas increases, so that the adhering substance easily adheres to the EGR passage, the EGR valve, and the like, which may reduce the reliability of the apparatus. Conventionally, as an EGR device provided with a cooling device for cooling EGR gas, for example,
Japanese Unexamined Patent Application Publication No. 7-180620 and the like are known.

FIG. 8 shows a cooling device arranged in this type of EGR device. This cooling device is arranged in a pipe connecting the exhaust manifold and the EGR valve. This cooling device is configured by arranging a large number of pipes 6 in the axial direction of a metal outer cylinder 5, as shown in FIG.
Both ends of the pipe 6 are supported by an end plate 7. A cooling water inlet pipe 8 and an outlet pipe 9 are attached to the outer periphery of the outer cylinder 5.

Further, flange portions 10 and 11 are formed at the upper end and the lower end of the outer cylinder 5, respectively. A pipe 12 from the exhaust manifold is connected to the upper flange 10 via a mounting flange 13, and a pipe 14 to the EGR valve is connected to the lower flange 11 via a mounting flange 15. In this cooling device, EGR gas is introduced into the pipe 6 from the pipe 12 on the exhaust manifold side,
After being cooled by cooling water flowing between the pipes 6 in the outer cylinder 5, the cooling water is led out to a pipe 14 on the EGR valve side.

[0007]

However, in such a conventional EGR gas cooling device, since the inlet pipe 8 and the outlet pipe 9 are attached to the outer cylinder 5, a plurality of parts are required. There was a problem that cost and assembly cost increased. In addition, since the temperature of the flange portion 10 side of the outer cylinder 5 becomes high due to the flow of the EGR gas, the outer cylinder 5 must be formed of a heat-resistant metal or the like, and there is a problem that the weight increases.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide an EGR gas cooling device capable of greatly reducing the weight as compared with the related art.

[0009]

In the EGR gas cooling apparatus according to the present invention, a heat exchange section in which both ends of a plurality of pipes are fixed by end plates is accommodated in an EGR pipe for recirculating exhaust gas to an intake system. In an EGR gas cooling device having an outer cylinder through which EGR gas flows, and an inlet pipe and an outlet pipe for cooling water formed on the outer periphery of the outer cylinder, the outer cylinder is formed of resin, An exhaust-side relay pipe and an intake-side relay pipe are connected to an exhaust-side open end and an intake-side open end of the outer cylinder, and an exhaust-side end of the heat exchange unit is protruded from the exhaust-side open end. I do.

[0010] According to a second aspect of the present invention, in the EGR gas cooling apparatus according to the first aspect, an intake side end of the heat exchanging portion protrudes from the intake side opening end of the outer cylinder. Features. According to a third aspect of the present invention, there is provided the EGR gas cooling apparatus according to the first or second aspect, wherein an inlet pipe and an outlet pipe are integrally formed with the outer cylinder.

According to a fourth aspect of the present invention, there is provided an EGR gas cooling apparatus according to any one of the first to third aspects, wherein the outer cylinder is connected to the exhaust-side relay pipe and the intake-side relay pipe. , And are connected via a seal member. According to a fifth aspect of the present invention, there is provided the EGR gas cooling device according to any one of the first to fourth aspects, wherein a mounting portion for mounting in an engine room is integrally formed on an outer periphery of the outer cylinder. It is characterized by the following.

According to a sixth aspect of the present invention, there is provided an EGR gas cooling apparatus according to any one of the first to fifth aspects, wherein the intake-side relay pipe is formed of a resin. .

(Effect) In the EGR gas cooling device of the first aspect, the exhaust-side relay pipe and the intake-side relay pipe are connected to the exhaust-side open end and the intake-side open end of the outer cylinder made of resin, and the heat exchange part is The heat exchange portion is housed in the outer cylinder in a state where the end on the exhaust side protrudes from the opening end on the exhaust side of the outer cylinder into the exhaust relay pipe.

[0014] Then, the cooling water flows into the heat exchange section from the inlet pipe formed in the heat exchange section, and the EGR gas flowing from the exhaust side relay pipe is first passed through the heat exchange section projecting into the intake side relay pipe. The EGR gas is cooled to a temperature equal to or lower than the heat resistant temperature of the outer cylinder, and then the EGR gas is cooled to a desired temperature by a heat exchange unit in the outer cylinder, and is circulated from the intake side relay pipe to the intake system,
The heat-exchanged cooling water is discharged from the outlet pipe.

In the EGR gas cooling device according to the second aspect, the heat exchange portion is accommodated in the outer cylinder with the intake end of the heat exchange portion protruding from the intake end opening end of the outer cylinder. The area is increased, and the EGR gas is cooled with high heat exchange efficiency. In the EGR gas cooling device of the third aspect, the inlet pipe and the outlet pipe are formed integrally with the outer cylinder, the structure of the parts is simplified, and the cost of the parts is greatly reduced as compared with the conventional case.

In the EGR gas cooling device according to the fourth aspect, the outer cylinder is easily and closely connected to the exhaust-side relay pipe and the intake-side relay pipe via a seal member. EG according to claim 5
In the R gas cooling device, a mounting portion is integrally formed on the outer periphery of the outer cylinder, and the cooling device is easily mounted in the engine room. In the EGR gas cooling device according to the sixth aspect, the intake-side relay pipe is formed of resin, and the intake-side relay pipe is easily connected to the outer cylinder and the intake system.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 and FIG.
1 shows a first embodiment (claims 1 to 5) of a GR gas cooling device, and reference numeral 21 denotes a long outer cylinder made of a resin such as nylon 66, for example.

An inlet pipe 23 for cooling water is integrally formed on the outer periphery of the outer cylinder 21 on the side of the processing end 21a on the suction side.
An outlet pipe 25 is integrally formed on the outer periphery of the outer pipe 21 on the side opposite to the inlet pipe 23 on the exhaust-side opening end 21b side. Inlet pipe 23 and outlet pipe 25 on the outer periphery of outer cylinder 21
A mounting portion 27 for mounting the outer cylinder 21 in an engine room or the like is integrally formed therebetween.

At the intake side open end 21a and the exhaust side open end 21b of the outer cylinder 21, an intake side relay pipe 29 and an exhaust side relay pipe 31, which are made of, for example, stainless steel and whose leading end sides are reduced in diameter, are arranged. ing. An annular convex portion 29a is formed on the distal end side of the intake side relay pipe 29. A flange portion 31a is formed at the tip of the exhaust-side relay pipe 31.

An annular groove 29b is formed on the outer periphery of the intake-side relay pipe 29 on the outer cylinder 21 side.
An O-ring 33a is attached. In addition, the outer cylinder 21
An annular groove 21c is formed on the inner periphery of the intake side relay pipe 29 side, and the annular groove 21c and the annular groove 29b are
a, and the outer cylinder 21 and the intake-side relay pipe 29 are connected in close contact with each other.

On the other hand, a thick part 21d is formed at the end of the outer cylinder 21 on the exhaust side relay pipe 31 side, and an annular groove 21e is formed on the exhaust side relay pipe 31 side of the thick part 21d. I have. An O-ring 33b is attached to the annular groove 21e. An annular flange 31b is formed at an end of the exhaust-side relay pipe 31 on the outer cylinder 21 side. The flange portion 31b and the thick portion 21d are in close contact with each other via an O-ring 33b.

The flange portion 31b and the thick portion 21 are in close contact with each other.
For example, semicircular clips 35 and 35 made of, for example, stainless steel and having a U-shaped cross section are attached so as to cover d, and the exhaust-side relay pipe 31 and the outer cylinder 21 are connected in close contact with each other.

Further, a plurality of pipes 37 made of, for example, stainless steel are arranged in the outer cylinder 21 along the axial direction of the outer cylinder 21. At both ends of these pipes 37, circular end plates 39, 39 made of, for example, stainless steel are fixed through the ends of the pipes 37, and are fixed by the pipes 37 and the end plates 39, 39. , A heat exchange part 41 is formed.

The exhaust-side end of the heat exchange section 41 projects from the exhaust-side opening end 21 b of the outer cylinder 21 and extends into the exhaust-side relay pipe 31. The intake-side end of the heat exchange section 41 projects from the intake-side opening end 21 a of the outer cylinder 21 and extends into the intake-side relay pipe 29. The above-described EGR gas cooling device is assembled as described below.

That is, first, as shown in FIG. 3, end plates 39, 39 are arranged at both ends of a plurality of pipes 37, and a heat exchange section 41 is formed. Next, the outer circumferences of the end plates 39, 39 are in contact with the inner circumferences of the exhaust-side relay pipe 31 and the intake-side relay pipe 29. In this state, the pipe 37, the end plates 39, 39, the exhaust-side relay pipe 31, and the intake-side relay pipe 29 are integrally brazed with, for example, a nickel brazing material.

Next, as shown in FIG.
The O-ring 33a and the O-ring 33b are attached to the 9 annular grooves 29b and the annular groove 21e of the thick portion 21d of the outer cylinder 21. Further, the intake side relay pipe 29 brazed integrally is connected to the outer cylinder 2 from the exhaust side opening end 21b of the outer cylinder 21.
1, the annular groove 29b of the intake-side relay pipe 29 and the annular groove 21c of the outer cylinder 21 are fitted via an O-ring 33a.

At the same time, the thick portion 21d of the outer cylinder 21 and the flange 31b of the exhaust-side relay pipe 31 are brought into close contact with each other via the O-ring 33b. Then, the flange portion 31b and the thick portion 21d are fixed by the semicircular clips 35, 35, and E in the present embodiment.
Assembly of the GR gas cooling device is completed.

In the above-described EGR gas cooling device, the EGR gas is cooled as described below. That is, as shown in FIG. 5, first, the cooling water 43 flows into the outer cylinder 21 from the inlet pipe 23. Further, the EGR gas 45 flows into the exhaust-side relay pipe 31 from the flange portion 31a and flows to the exhaust system side in the pipe 37. At this time, the EGR gas 45 is cooled to a temperature equal to or lower than the heat resistant temperature of the outer cylinder 21 by the heat exchange part 41 projecting into the exhaust-side relay pipe 31.

Further, the EGR gas 45 is circulated through the pipe 37 toward the intake system side, and is supplied to the heat exchange section 4 in the outer cylinder 21.
1, after being cooled to a desired temperature by the intake side relay pipe 2
9 to the intake system. Then, the cooling water 43 that has undergone heat exchange and has a raised temperature is discharged from the outlet pipe 25. In the EGR gas cooling device configured as described above, the heat exchange unit 4
1 is housed in the outer cylinder 21 with the exhaust-side end of the heat exchange section 41 protruding into the exhaust-side relay pipe 31 from the exhaust-side opening end 21b of the outer cylinder 21, so that it flows in from the exhaust-side relay pipe 31 side. The EGR gas 45 can be cooled by the heat exchange part 41 protruding into the exhaust-side relay pipe 31, and the outer cylinder 21 conventionally formed of metal due to the problem of heat resistance can be formed of resin. .

For this reason, the weight of the outer cylinder 21 can be significantly reduced as compared with the conventional case. In addition, the heat exchange unit 41 is connected to the intake side open end 21 a
Since it is housed in the outer cylinder 21 in a state of protruding from the outer cylinder 21, the heat transfer area of the heat exchange section 41 can be increased, and the EGR gas 45 can be cooled with high heat exchange efficiency. further,
Since the inlet pipe 23 and the outlet pipe 25 are formed integrally with the outer cylinder 21, the structure of the parts can be simplified, and the cost of the parts can be greatly reduced as compared with the conventional case.

The annular groove 29b of the intake-side relay pipe 29 and the annular groove 21c of the outer cylinder 21 are fitted via an O-ring 33a, and the flange 31b of the exhaust-side relay pipe 31 and the annular groove of the outer cylinder 21 are fitted. Since the outer cylinder 21e and the exhaust-side relay pipe 31 and the intake-side relay pipe 2 are easily brought into close contact with each other via the O-ring 33b.
9 can be connected in close contact. Since the mounting portion 27 is integrally formed on the outer periphery of the outer cylinder 21, the cooling device can be easily mounted in the engine room.

FIG. 6 shows a second embodiment (corresponding to claim 6) of the EGR gas cooling device of the present invention. In the present embodiment, the intake-side relay pipe 29 is formed of, for example, a silicone resin or the like.
The structure on the intake side of the first embodiment is different from that of the first embodiment.

The end plate 39 on the intake side of the heat exchange part 41 is formed to be thick, and an annular groove 39a is formed on the outer periphery of the end plate 39. The O-ring 33 is provided in the annular groove 39a.
a is attached, and the outer cylinder 21 is
The annular groove 21c and the annular groove 39a are fitted. The intake side opening end 21a of the outer cylinder 21 is connected to the intake side relay pipe 29.
And the outer periphery of the intake side relay pipe 29 is
It is fixed at.

In the EGR gas cooling device of this embodiment, substantially the same effects as in the first embodiment can be obtained. However, in this embodiment, since the intake side relay pipe 29 is formed of silicone resin, Intake side relay pipe 29
It can be easily connected to the outer cylinder 21 and the intake system. In the above-described first embodiment, an example in which the outer cylinder 21 is formed of nylon 66 has been described. However, the present invention is not limited to this embodiment. For example, the outer cylinder 21 may be formed of an aromatic polyamide resin or the like. May be.

In the above-described second embodiment, the example in which the intake side relay pipe 29 is formed of a silicone resin has been described. However, the present invention is not limited to this embodiment. May be formed.

[0036]

In the EGR gas cooling device according to the first aspect, the heat exchange section is accommodated in the outer cylinder with the exhaust end of the heat exchange section protruding from the exhaust opening end of the outer cylinder into the exhaust relay pipe. Therefore, the EGR gas flowing from the exhaust-side relay pipe can be cooled by the heat exchange portion protruding into the exhaust-side relay pipe, and the outer cylinder, which was conventionally formed of metal due to a problem of heat resistance, is formed of resin. can do.

For this reason, the weight of the outer cylinder can be significantly reduced as compared with the conventional case. In the EGR gas cooling device according to the second aspect, the heat exchange section is housed in the outer cylinder with the intake end of the heat exchange section protruding from the intake end opening end of the outer cylinder, so that the heat transfer area of the heat exchange section is reduced. The EGR gas can be cooled with high heat exchange efficiency. EG according to claim 3
In the R gas cooling device, since the inlet pipe and the outlet pipe are formed integrally with the outer cylinder, the structure of parts can be simplified, and the cost of parts can be greatly reduced as compared with the conventional case.

In the EGR gas cooling device according to the fourth aspect, since the outer cylinder is connected to the exhaust-side relay pipe and the intake-side relay pipe via the seal member, the outer cylinder is easily connected to the exhaust-side relay pipe and the intake-side relay pipe. The tube and the tube can be connected in close contact. In the EGR gas cooling device according to the fifth aspect, since the mounting portion is integrally formed on the outer periphery of the outer cylinder, the cooling device can be easily mounted in the engine room. In the EGR gas cooling device according to claim 6, since the intake-side relay pipe is formed of resin,
This intake side relay pipe can be easily connected to the outer cylinder and the intake system side.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of an EGR gas cooling device of the present invention.

FIG. 2 is an exploded perspective view of FIG.

FIG. 3 is a perspective view showing a state where a heat exchange unit is brazed to an exhaust-side relay pipe and an intake-side relay pipe.

FIG. 4 is a perspective view showing a state in which a brazed heat exchange unit, an exhaust-side relay pipe, and an intake-side relay pipe are housed in an outer cylinder.

FIG. 5 is a cross-sectional view showing a flow state of cooling water and EGR gas.

FIG. 6 is a cross-sectional view showing an example in which the intake side relay pipe is formed of resin.

FIG. 7 is an explanatory view showing a conventional EGR device.

FIG. 8 is a perspective view showing a conventional EGR gas cooling device.

FIG. 9 is a sectional view showing details of a main part of FIG. 8;

[Explanation of symbols]

 Reference Signs List 21 outer cylinder 21a intake side open end 21b exhaust side open end 23 inlet pipe 25 outlet pipe 27 attachment part 29 intake side relay pipe 31 exhaust side relay pipe 33a, 33b O-ring (seal member) 37 pipe 39 end plate 41 heat exchange part 43 Cooling water 45 EGR gas

Claims (6)

[Claims] 1. EGR for recirculating exhaust gas to an intake system
Both ends of the plurality of pipes (37) are connected to end plates (39, 3) in the pipeline.
An outer cylinder (21) in which the heat exchange part (41) fixed in 9) is accommodated and through which the EGR gas (45) flows is arranged, and an outer cylinder (21) for cooling water (43) is provided around the outer cylinder (21). E formed by forming an inlet pipe (23) and an outlet pipe (25)
In the GR gas cooling device, the outer cylinder (21) is formed of resin, and an exhaust-side relay pipe (31) and an exhaust-side relay pipe (21) are provided at the exhaust-side open end (21b) and the intake-side open end (21a) of the outer cylinder (21). An EGR gas cooling device, wherein an intake-side relay pipe (29) is connected, and an exhaust-side end of the heat exchange section (41) projects from the exhaust-side open end (21b). 2. The EGR gas cooling device according to claim 1, wherein an end of the heat exchange section (41) on the intake side is connected to the outer cylinder (21).
An EGR gas cooling device characterized by projecting from the intake side opening end (21a). 3. The EGR gas cooling device according to claim 1, wherein an inlet pipe (23) and an outlet pipe (25) are formed integrally with the outer cylinder (21).
Gas cooling device. 4. The EGR gas cooling device according to claim 1, wherein the outer cylinder (21), the exhaust-side relay pipe (31), and the intake-side relay pipe (29) are connected to each other. To the sealing member (33a, 3
An EGR gas cooling device characterized by being connected via 3b). 5. The EGR gas cooling device according to claim 1, wherein a mounting portion (27) for mounting in an engine room is integrally formed on an outer periphery of the outer cylinder (21). EG characterized by becoming
R gas cooling device. 6. The EGR gas cooling device according to claim 1, wherein the intake-side relay pipe (29) is formed of a resin.