JP2000146462A - Double-pipe heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double-pipe heat exchanger capable of improving the reliability by restricting the movement of a heat radiating member by its shape. SOLUTION: An EGR cooler 10 is constituted as a double-pipe structure formed of an inner pipe 11 and an outer pipe 12. A radiation fin 16 is stored in and fixed to the inner pipe 11. The radiation fin 16 is fixed to an inner circumferential surface of the inner pipe 11. A movement restriction projecting part 11a is formed inside the inner pipe 11 through the recessing (caulking) from an outer circumference of the radiation fin 16. An engagement recessed part 16a is brought into contact with the outer circumference of the radiation fin 16 in a recessed manner in a condition where an engagement recessed part 16a is engaged with the projecting part 11a corresponding to the movement restriction projecting part 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-pipe heat exchanger for cooling high-temperature exhaust gas extracted from an exhaust system, for example, in an exhaust gas recirculation system for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in order to reduce nitrogen oxides in exhaust gas of an internal combustion engine, a part of the exhaust gas is taken out from an exhaust system (exhaust manifold) and recirculated to an intake system (intake manifold). A recirculation device (hereinafter, referred to as an “EGR device”) is known. The EGR device has a double-pipe heat exchanger (hereinafter, referred to as "EGR gas") for cooling high-temperature exhaust gas (hereinafter, referred to as "EGR gas") taken out of an exhaust system before re-introducing it into an intake system.
"GR cooler". ) Is provided.

[0003] As shown in FIGS. 8 and 9, an E is disposed in the exhaust recirculation passage (not shown) of the EGR device.
The GR cooler 50 has an inner pipe 51 through which EGR gas flows, and an outer peripheral surface of the inner pipe 51 which is enclosed and fixed at both ends to an outer peripheral surface of the inner pipe 51. It has a double piping structure with an outer pipe 53 that partitions the annular flow passage 52. As shown in FIG. 9, a radiation fin 54 for promoting heat transfer is accommodated in the inner tube 51, and the outer periphery of the radiation fin 54 is fixed to the inner peripheral surface of the inner tube 51 by brazing. I have.

[0004] Cooling water is supplied to the outer pipe 53 through the flow passage 52.
And a discharge pipe 56 for discharging the cooling water in the flow passage 52. Cooling water for cooling the internal combustion engine is introduced into the flow passage 52 through an inlet pipe 55.
The cooling water flows through the flow passage 52, and flows through a discharge pipe 56 to a cooling water circulation circuit (not shown) of the internal combustion engine.
Is returned to. Heat exchange is performed between the high-temperature EGR gas and the cooling water via the inner pipe 51. As a result, EGR
The gas is cooled and reintroduced into the intake system of the internal combustion engine.

[0005]

The outer periphery of the radiating fin 54 is fixed to the inner peripheral surface of the inner tube 51 by brazing. Therefore, when the brazing portion is corroded, the radiation fins 54 may peel off from the inner peripheral surface of the inner tube 51 and fall off. When the heat radiation fins 54
Moves freely along the inner peripheral surface of the inner tube 51, and when a part or the whole of the inner tube 51 moves out of the coolable range, 2
The cooling effect of the double-pipe heat exchanger is reduced, causing a problem in reliability.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to improve the reliability by restricting the movement of a heat radiating member in a first cylindrical member. To provide a double-pipe heat exchanger that can perform the heat treatment.

[0007]

According to a first aspect of the present invention, a first cylindrical member through which a medium to be cooled flows is separated from an outer periphery of the first cylindrical member. A double-pipe type heat comprising a second tubular member surrounding and surrounding the first tubular member and defining a flow portion for a cooling medium between the first tubular member and a heat radiating member housed and fixed in the first tubular member. In the exchanger,
The gist of the invention is to provide a movement restricting projection which is formed inside the first cylindrical member and is engaged with the heat radiation member.

According to a second aspect of the present invention, there is provided a first cylindrical member through which a medium to be cooled flows, and a first cylindrical member surrounding the outer periphery of the first cylindrical member with a space therebetween, and cooling between the first cylindrical member and the first cylindrical member. In a double-pipe heat exchanger including a second tubular member that divides a circulation section for a medium and a heat radiating member housed and fixed in the first cylindrical member, a part of the heat radiating member is replaced with a first cylindrical member. It is the gist that it was bent together with.

(Operation) Therefore, according to the first aspect of the present invention, the heat radiating member is dropped from the inner peripheral surface of the first cylindrical member due to corrosion or the like, and is about to move along the inner peripheral surface of the first cylindrical member. Is also restricted by a movement restricting projection that is formed inside the first cylindrical member and engages with the heat radiating member. As a result, the cooling effect of the double-pipe heat exchanger is stabilized, and the reliability of the double-pipe heat exchanger can be improved.

According to the second aspect of the present invention, even if the heat radiating member drops from the inner peripheral surface of the first cylindrical member due to corrosion or the like and tries to move along the inner peripheral surface of the first cylindrical member, the heat radiating member can be removed. The bent portion is caught on the inner peripheral surface of the first cylindrical member, and its movement is restricted. As a result, the cooling effect of the double-pipe heat exchanger is stabilized, and the reliability of the double-pipe heat exchanger can be improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in an exhaust gas recirculation device for an internal combustion engine (hereinafter, referred to as an "EGR device") will be described with reference to the drawings.

As shown in FIG. 1 and FIG.
A double-pipe heat exchanger (hereinafter, referred to as an “EGR cooler”) 10 provided in the middle of an exhaust circulation passage (not shown) in the GR device has a cooling medium taken out from the exhaust system of the internal combustion engine inside. Pipe 1 as a first cylindrical member through which high-temperature exhaust gas (hereinafter, referred to as “EGR gas”) flows
1 is provided.

The inner tube 11 is made of a material having high thermal conductivity, for example, an aluminum alloy, and has an outer tube 1 on its outer periphery as a second cylindrical member so as to surround the outer periphery of the inner tube 11 at a distance.
2 are arranged. Both ends of the outer tube 12 are gradually reduced in diameter, and are fixed to the outer peripheral surface of the inner tube 11 by welding or the like. A flow passage 13 is formed between the outer peripheral surface of the inner tube 11 and the inner peripheral surface of the outer tube 12 for flowing cooling water as a cooling medium having an annular cross section. That is, the EGR cooler 10 is configured as a double pipe structure of the inner pipe 11 and the outer pipe 12.

The outer pipe 12 is provided with an introduction pipe 14 for introducing cooling water into the flow path 13 and a discharge pipe 15 for discharging cooling water in the flow path 13. Cooling water for cooling the internal combustion engine is supplied to the flow passage 13 through an introduction pipe 14, and the cooling water flows through the flow passage 13, and then flows through a discharge pipe 15 to a cooling water circulation circuit (not shown in the drawing) of the internal combustion engine. )
Is returned to. Therefore, the EGR cooler 10 can cool the EGR gas passing through the coolable section C where the cooling water flowing through the flow passage 13 and the outer peripheral surface of the inner pipe 11 are in contact.

A radiating fin 16 as a radiating member is housed and fixed to the inner tube 11. As shown in FIG. 2, the radiating fins 16 are formed in a substantially radial cross section (substantially star-shaped cross section) in the radial direction of the inner tube 11 and have a predetermined length in the tube axis direction of the inner tube 11 (this embodiment). In this case, both ends are formed so as to have a length that is located in the coolable section C.
1 is fixed to the inner peripheral surface.

As shown in FIGS. 1 and 3, an annular movement restricting projection 11a is formed by caulking on the inner periphery of the inner pipe 11 in the coolable section C. In the present embodiment, one movement restricting projection 11a is formed at about the center of the inner pipe 11 in the pipe axis direction. At this time, on the outer periphery of the radiation fin 16, an engagement concave portion 16a is formed in a recessed state corresponding to the movement restricting projection 11a in a state of being engaged with the projection 11a.

The radiating fins 16 are formed by bending a single metal plate having a high thermal conductivity, such as an aluminum alloy, into a wavy (substantially bellows) shape by pressing or the like. It is rounded (corrugated cylindrical shape) so as to be in contact with the peripheral surface and inserted into the inner tube 11. The radiating fins 16 are formed such that the outer surface of each of the ridges 16b is
Is fixed to the inner peripheral surface of the inner tube 11 by brazing to the inner peripheral surface of the inner tube 11. Then, the inner tube 1 is depressed (caulked) from the outer periphery of the inner tube 1 by press working or the like.
A movement restricting projection 11a is formed on the inner periphery of the fin 1, and an engagement recess 16a is formed on the outer periphery of the radiation fin 16. Finally, the outer tube 12 is fixed to the outer periphery of the inner tube 11 by welding or the like so as to surround the outer periphery of the inner tube 11 with a space therebetween.

When high-temperature EGR gas flows into the inner tube 11 of the EGR cooler 10 and the EGR gas contacts the radiating fins 16, heat of the high-temperature EGR gas is taken by the radiating fins 16 and 11 is transmitted. Then, the heat transmitted to the inner pipe 11 is transmitted to the cooling water flowing through the flow passage 13 and is discharged. That is, the high-temperature EGR gas flows between the radiation fin 16 and the inner pipe 1 between the EGR gas and the cooling water.
The heat is exchanged through 1 to be cooled.

Therefore, the double-pipe heat exchanger (EGR cooler) 10 of the present embodiment has the following features. (1) In the present embodiment, a movement restricting projection 11 a is formed on the inner peripheral surface of the inner tube 11 so as to protrude, and an engagement concave portion 16 a is formed on the outer periphery of the radiation fin 16. In addition, the movement restricting projection 11a engages with the engagement recess 16a.

Therefore, the brazing portion between the radiation fin 16 and the inner tube 11 is corroded or the like, so that the radiation fin 16 is
When the heat radiation fins 16 fall from the inner peripheral surface of the
1 along the inner peripheral surface of the engagement recess 16
a is a movement restricting projection 11a formed on the inner peripheral surface of the inner pipe 11.
And its movement is regulated.

As a result, the radiation fins 16 are restricted in shape from being immovable in the inner tube 11, so that the cooling effect of the double-pipe heat exchanger 10 is stabilized without becoming unstable, and The reliability of the pipe-type heat exchanger 10 can be improved.

(2) In the present embodiment, the radiating fins 16 are fixed to the inner peripheral surface of the inner tube 11 and then dented (caulked) from the outer periphery of the inner tube 11 by press working or the like. Is formed on the inner periphery of the fin 16 and the engagement recess 16a is formed on the outer periphery of the radiating fin 16. At this time, the movement regulating protrusion 11a is formed on the inner circumference of the inner pipe 11.
The heat radiation fins 16 are formed by caulking.
An engagement recess 16a is formed on the outer periphery of the head.

Therefore, the movement regulating projection 11a and the engagement recess 1 can be formed only by adding one press working in the current manufacturing process.
6a can be easily provided. As a result, the present invention can be easily implemented.

The above embodiment may be modified as follows. In the above-described embodiment, the movement control protrusion 11a is formed at a position approximately at the center of the inner tube 11 in the tube axis direction. For example, the movement regulating protrusions 11a may be provided at a plurality of places, for example, two places and three places. In this case, substantially the same effects as in the above embodiment can be obtained.

In the above-described embodiment, only one heat radiation fin 16 is arranged in the inner tube 11.
May be divided into a plurality of, for example, two radiation fins 16 and arranged at a predetermined distance from each other. In this case, if the movement restricting protrusions 11a are provided in at least one place by swaging from the outer periphery of the inner tube 11 according to the installation location of each heat radiation fin 16, substantially the same effect as in the above embodiment can be obtained.

In the above embodiment, as shown in FIG. 4 and FIG. 5, the inner tube 11 is located outside the both ends of the radiating fin 16 and at a position close to the both ends according to the installation location of the radiating fin 16. The movement restricting protrusions 11a may be provided by caulking from the outer periphery. At this time, the inner pipe 11
Are formed on the inner periphery of the radiating fin 16 on both ends.

Accordingly, the radiation fin 16 and the inner tube 11 may be corroded due to corrosion or the like.
When the heat radiation fins 16 fall from the inner peripheral surface of the
1 along the inner peripheral surface of the radiating fin 1
6 is fixed at its both ends by a movement restricting projection 11a formed on the inner peripheral surface of the inner tube 11, and its movement is restricted.

As a result, the radiation fins 16 are restricted in shape from being immovable in the inner tube 11, so that the cooling effect of the double-pipe heat exchanger 10 is not unstable and stable. The reliability of the pipe-type heat exchanger 10 can be improved.

Further, since the outer periphery of the radiation fin 16 does not need to be deformed, that is, only the inner tube 11 needs to be deformed,
Processing can be performed more easily than in the above embodiment. In the above-described embodiment, the movement restricting projection 11a is formed in an annular shape.

In the above embodiment, as shown in FIG. 6, a plurality of, for example, two radiation fins 1 are provided in the inner tube 11.
When the inner tubes 11 and the outer tubes 12 are arbitrarily bent according to the installation location of the EGR cooler 10 as shown in FIG. So that the inner tube 11 and the outer tube 12
It may be folded and implemented together. That is, in FIGS. 6 and 7, the inner pipe 11 and the outer pipe 12 are bent in the range E.

Therefore, the radiating fin 16 and the inner tube 11 may be corroded due to corrosion or the like.
When the radiating fins 16 try to move along the inner peripheral surface of the inner tube 11 when the radiating fins 16 drop off from the inner peripheral surface of the inner tube 11, the bent portions 16c of the radiating fins 16 Its movement is restricted by being caught on the surface.

As a result, the two radiating fins 16 are restricted in shape from being immovable in the inner tube 11, so that the cooling effect of the double-pipe type heat exchanger 10 is stabilized without becoming unstable.
The reliability of the double-pipe heat exchanger 10 can be improved. Also, the inner pipe 1 is pressed from the outer periphery of the inner pipe 11 by pressing.
Since there is no need to provide the movement restricting projection 11a on the inner periphery of the first device 1, the number of manufacturing steps can be reduced.

The number of the radiation fins 16 may be one. In the above embodiment, the inner tube 11 or the radiation fin 1
Although 6 was implemented with an aluminum alloy, it is not limited to an aluminum alloy, and may be implemented with, for example, a copper alloy, a zinc alloy, or the like as long as the material has high thermal conductivity. Further, the radiation fins 16 may be made of stainless steel (for example, SUS304) having high heat resistance, high corrosion resistance, and high thermal conductivity. In this case, substantially the same effects as in the above embodiment can be obtained.

In the above embodiment, the radiation fins 1
6 is fixed to the inner peripheral surface of the inner tube 11 by brazing, but may be fixed by welding, press fitting, or the like. In this case, substantially the same effects as in the above embodiment can be obtained.

In the above embodiment, the double-pipe heat exchanger is used for cooling the EGR gas of the internal combustion engine, but not for the gas such as the EGR gas but for cooling the liquid or the like. Is also good. Even in this case, the same effect as that of the present embodiment can be obtained.

In the above embodiment, the EGR cooler 10 is constituted by the cylindrical inner pipe 11 and the outer pipe 12.
For example, the inner tube 11 and the outer tube 12 may have a rectangular or elliptical cylindrical shape. Even in this case, the same effect as in the above embodiment can be obtained.

Next, technical ideas other than those described in the claims which can be understood from the embodiment and other examples will be described below together with their effects. (1) A first cylindrical member through which the medium to be cooled flows, and a first cylindrical member surrounding the outer periphery of the first cylindrical member with a space therebetween, and defining a cooling medium flow part between the first cylindrical member and the first cylindrical member. 2 comprising a two-cylinder member and a heat radiating member housed and fixed in the first cylinder member
In a double-pipe heat exchanger, a double-pipe heat exchanger is provided with a movement restricting projection formed to protrude inside the first cylindrical member and sandwich both ends of a heat radiating member.

Therefore, even if the heat dissipating member drops from the inner peripheral surface of the first cylindrical member due to corrosion or the like and moves along the inner peripheral surface of the first cylindrical member, the heat dissipating member is formed so as to protrude inside the first cylindrical member. Are restricted by the movement restricting projections that sandwich both ends of the.
As a result, the cooling effect of the double-pipe heat exchanger is stabilized,
The reliability of the double-pipe heat exchanger can be improved.

[0039]

According to the first and second aspects of the present invention, the cooling effect of the double-pipe heat exchanger is stabilized, and the reliability of the double-pipe heat exchanger can be improved.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an EGR cooler according to an embodiment.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a perspective view of a main part of an inner tube and a radiation fin according to the embodiment.

FIG. 4 is a perspective view of a main part of an inner tube and a radiation fin according to another embodiment.

FIG. 5 is a front sectional view of an EGR cooler according to another embodiment.

FIG. 6 is a front sectional view of an EGR cooler according to another embodiment before bending.

FIG. 7 is a front sectional view of an EGR cooler according to another embodiment after bending.

FIG. 8 is a front sectional view of a conventional EGR cooler.

FIG. 9 is a sectional view taken along line BB in FIG. 8;

[Explanation of symbols]

Reference numeral 10: EGR cooler (double-pipe heat exchanger), 11: inner pipe as first cylindrical member, 11a: movement regulating protrusion, 12 ...
Outer tube as second cylindrical member, 13 ... flow passage, 14 ... introduction tube, 15 ... discharge tube, 16 ... radiating fins as heat radiating member, 16a ... engagement recess.

Claims (2)

[Claims] 1. A first cylindrical member through which a medium to be cooled is circulated, and an outer periphery of the first cylindrical member is separated from the first cylindrical member, and a cooling medium flow portion is defined between the first cylindrical member and the first cylindrical member. In a double-pipe heat exchanger comprising a second cylindrical member to be formed and a heat radiating member housed and fixed in the first cylindrical member, a movement that is formed to protrude inside the first cylindrical member and engages with the heat radiating member. A double-pipe heat exchanger having a regulating projection. 2. A first cylindrical member through which a medium to be cooled is circulated, and an outer periphery of the first cylindrical member is spaced apart from the first cylindrical member, and a cooling medium flow portion is defined between the first cylindrical member and the first cylindrical member. In a double-pipe heat exchanger including a second cylindrical member to be heated and a heat radiating member housed and fixed in the first cylindrical member, a part of the heat radiating member is bent together with the first cylindrical member. Double-pipe heat exchanger.