JP2000176578A - Manufacture of fluid cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a fluid cooler capable of improving heat exchanging efficiency and reliability. SOLUTION: An EGR cooler 10 is composed of a double piping structure of an inner pipe 11 and an outer pipe 12. A heat radiating fin 16 is housed and fixed into and to the inner pipe 11. The heat radiating fin 16 is manufactured by drawing a pipe stock of the outside diameter d1 with a roll and a die or the like. And the heat radiating fin 16 is inserted into the inner pipe 11, the inner pipe 11 is diametrically reduced and plastically worked to such an extent that the inner peripheral surface of the inner pipe 11 abuts on the outer peripheral surface of the heat radiating fin 16, and thereafter the heat radiating fin 16 is fixed to the inside of the inner pipe 11 by brazing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a fluid cooling device, and more particularly to a double piping system for cooling high-temperature exhaust gas extracted from an exhaust system in an exhaust gas recirculation device of an internal combustion engine. The present invention relates to a manufacturing method suitable for manufacturing a heat exchanger.

[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.

[0005] As shown in FIGS. 5 and 6, an E is disposed in the exhaust passage (not shown) in 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. 6, a radiation fin 54 for promoting heat transfer is housed and fixed in the inner tube 51.

The outer pipe 53 is provided with an introduction pipe 55 for introducing cooling water into the flow passage 52 and a discharge pipe 56 for discharging cooling water in the flow passage 52. Cooling water for cooling the internal combustion engine is supplied into the flow passage 52 through an introduction pipe 55, and the cooling water flows through the flow passage 52, and a cooling water circulation circuit (not shown) of the internal combustion engine through a discharge pipe 56. 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, the EGR gas is cooled and re-introduced into the intake system of the internal combustion engine.

[0005]

In the manufacture of the EGR cooler 50, first, for example, Japanese Patent Publication No. 3-687.
As disclosed in Japanese Patent Application Publication No.
Is drawn out of a pipe material to produce a substantially radial cross section (substantially star-shaped cross section), and then inserted into the inner tube 51 to insert the inner tube 5 into the inner tube 5.
1 is fixed to the inner peripheral surface by brazing. In this case, the outer diameter d1 of the radiating fin 54 is slightly smaller than the inner diameter d2 of the inner tube 51 so that the radiating fin 54 can be easily inserted into the inner tube 51. Therefore, when the radiation fin 54 is inserted into the inner tube 51 and fixed to the inner peripheral surface of the inner tube 51 by brazing, the radiation fin 54 is fixed while keeping its outer periphery concentric with the inner periphery of the inner tube 51. Is difficult. As a result, the radiation fins 54 may be offset in the inner tube 51. For example, in FIG. 5, when it is shifted downward, the distance t (= d2-
The gap 57 of d1) is generated. In this state, the radiation fins 54
Is fixed to the inner peripheral surface of the inner tube 51 by brazing, since the thickness of the upper and lower brazings varies, the radiation fins 54 may not be directly fixed to the inner tube 51 in the upper brazing portion having a large gap 57. is there. This is the EGR cooler 50
This is a problem in improving the heat exchange efficiency and the reliability.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing a fluid cooling device capable of improving heat exchange efficiency and reliability. .

[0007]

In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a tubular member through which a medium to be cooled flows, and a heat radiating member housed and fixed in the tubular member. In the method for manufacturing a fluid cooling device provided with, the heat dissipating member is inserted into the cylindrical member, and the cylindrical member is reduced in diameter plastic working until the inner peripheral surface of the cylindrical member comes into contact with the outer peripheral surface of the heat dissipating member. The gist is that the heat radiating member is fixed in the cylindrical member.

According to the first aspect of the present invention, between the inner periphery of the tubular member and the outer periphery of the radiating member, the radiating member is prevented from being biased to one side in the tubular member. You. Therefore, there is no variation in brazing thickness when the heat radiation member is fixed to the inner peripheral surface of the cylindrical member by, for example, brazing, and there is no place where the heat radiation member does not directly adhere to the cylindrical member due to the fluctuation. As a result, since the brazing of the heat radiating member and the cylindrical member is stabilized, the heat exchange rate and the reliability of the fluid cooling device can be improved.

[0009]

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 type heat exchanger (hereinafter, referred to as a fluid cooling device) provided in the middle of an exhaust circulation channel (not shown) in the GR device.
It is called “EGR cooler”. ) 10 is provided with an inner pipe 11 as a cylindrical member through which a high-temperature exhaust gas (hereinafter, referred to as “EGR gas”) as a medium to be cooled taken out of an exhaust system of the internal combustion engine flows.

The inner tube 11 is made of a material having high heat and corrosion resistance, for example, a stainless steel material, and has an outer tube 1 on its outer periphery 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 (water jacket) 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. The EGR cooler 10 is capable of cooling the EGR gas passing through a coolable section 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. The radiation fins 16 are made of a material having high heat and corrosion resistance, for example, a stainless steel material. In the present embodiment, as shown in FIG. 2, the radiation fins 16 are formed in a substantially radial cross section (substantially star-shaped cross section) in the radial direction of the inner tube 11. ing.

In manufacturing the inner tube 11 for accommodating and fixing the radiating fins 16, first, the radiating fins 16 are manufactured by extracting a pipe material having an outer diameter d1 into a shape shown in FIG. 3 by using a roll or a die. Then, after inserting the radiation fins 16 to a predetermined position in the inner tube 11 made of a pipe material having an inner diameter d2 (here, d2> d1), a range in which the radiation fins 16 are present in the inner tube 11 (FIG. 1 and FIG. 4, the diameter of the inner tube 11 is reduced and plastically processed to the extent that the inner peripheral surface of the inner tube 11 comes into contact with the outer peripheral surface of the radiation fin 16 over the range C). Finally, the radiation fins 16 are fixed in the inner tube 11 by brazing.

When high-temperature EGR gas flows into the inner tube 11 of the EGR cooler 10 and the EGR gas comes into contact with 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.

Next, the features of the double-pipe heat exchanger (EGR cooler) 10 of the present embodiment will be described below. (1) In this embodiment, the radiating fins 16 are inserted into the inner tube 11, and the inner tube 11 is subjected to diameter-reducing plastic working until the inner peripheral surface of the inner tube 11 comes into contact with the outer peripheral surface of the radiating fin 16. ,
The radiation fins 16 were fixed in the inner tube 11 by brazing.
Therefore, between the inner periphery of the inner tube 11 and the outer periphery of the radiating fins 16, the radiating fins 16 are prevented from being biased into the inner tube 11 and uniformly contact. That is, the radiation fin 16 is connected to the inner tube 1.
Variations in the brazing thickness when brazing to the inner peripheral surface of the inner tube 1 are eliminated, and there is no place where the radiation fins 16 do not directly adhere to the inner tube 11 due to the variation. As a result, since the brazing between the radiation fins 16 and the inner tube 11 is stabilized, the heat exchange rate and the reliability of the EGR cooler 10 can be improved.

(2) In this embodiment, the radiation fins 16
Was manufactured by drawing a pipe material having an outer diameter d1 into a shape shown in FIG. 3 using a roll or a die. Therefore, the accuracy of the outer diameter of the radiation fin 16 is improved. As a result, the degree of adhesion between the radiation fins 16 and the inner tube 11 is improved, so that the reliability of the EGR cooler 10 can be further improved.

The above embodiment may be modified as follows. In the above embodiment, the radiation fins 16 are
1, the radiation fins 16 are not limited to a substantially radial shape (substantially star-shaped), but are formed into, for example, a substantially gourd-shaped cross-section. It may be implemented. In this case, substantially the same effects as in the above embodiment can be obtained.

In the above-described embodiment, one radiating fin 16 is arranged at a predetermined length in the axial direction of the inner tube 11, but two or more radiating fins may be arranged.
In this case, substantially the same effects as in the above embodiment can be obtained.

In the above embodiment, the radiation fins 1
In each ridge protruding toward the center of the inner tube 11 in 6,
A plurality of holes or slits may be provided as turbulence generating means. In this case, in addition to the effect of the above-described embodiment, the EGR gas flowing into the EGR cooler 10 is disturbed by mutually entering and exiting each road through each hole or slit. Therefore, efficient heat exchange is performed between the high-temperature EGR gas and the cooling water via the radiation fins 16 and the inner pipe 11. As a result, the heat exchange rate of the EGR cooler 10 can be further improved.

In the above embodiment, the radiation fins 1
6 was manufactured by extracting a pipe material having an outer diameter d1 by using a roll or a die, but the invention is not limited to the above method. May be carried out by a plastic working method called flow forming. In this case, substantially the same effects as in the above embodiment can be obtained.

In the above embodiment, the inner tube 11 and the radiating fins 16 are made of stainless steel. However, the material is not limited to stainless steel. You may implement with a zinc alloy, an aluminum alloy, etc. In this case, substantially the same effects as in the above embodiment can be obtained.

In the above embodiment, the radiation fins 1
6 was fixed to the inner peripheral surface of the inner tube 11 by brazing, but is not limited to brazing, and may be fixed by, for example, welding. In this case, substantially the same effects as in the above embodiment can be obtained.

In the above embodiment, the double-pipe heat exchanger 10 is used for cooling the EGR gas of the internal combustion engine. You may. Even in this case, the same effect as in the above embodiment can be obtained.

In the above embodiment, the EGR cooler 10 is constituted by the cylindrical inner tube 11 and the outer tube 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.

In the above embodiment, the present invention is embodied in a double-pipe heat exchanger, but the present invention is not limited to a double-pipe heat exchanger. For example, the present invention may be embodied in a fluid cooling device that cools by a method such as the above. In this case, substantially the same effects 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) The method for manufacturing a fluid cooling device according to claim 1, wherein the heat radiating member is manufactured by a drawing process.

Therefore, in addition to the effect of the first aspect, the reliability of the fluid cooling device can be further improved.

[0029]

According to the first aspect of the present invention, the heat exchange efficiency and reliability of the fluid cooling device can be improved.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an EGR cooler according to the present invention.

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

FIG. 3 is a perspective view of a radiation fin.

FIG. 4 is a perspective view of an inner tube to which radiation fins are fixed.

FIG. 5 is a front sectional view of a conventional EGR cooler.

FIG. 6 is a sectional view taken along line BB in FIG. 5;

[Explanation of symbols]

10: EGR cooler (double pipe type heat exchanger) as a fluid cooling device, 11: inner pipe as a cylindrical member, 12 ... outer pipe,
Reference numeral 13 denotes a flow passage, and reference numeral 16 denotes a radiation fin as a radiation member.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuhiro Hosokawa 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yasufumi Sakakibara 1 1 Kitayama, Hashimecho Town, Okazaki City, Aichi F Terms (reference) 3G062 ED08 GA08 GA10 GA23 3L103 AA01 BB17 CC27 DD08 DD33 DD38

Claims (1)

[Claims] 1. A method for manufacturing a fluid cooling device, comprising: a tubular member through which a medium to be cooled is circulated; and a heat radiating member housed and fixed in the cylindrical member, wherein the heat radiating member is inserted into the cylindrical member. A method of manufacturing a fluid cooling device, comprising: reducing the diameter of a cylindrical member so that an inner peripheral surface of the cylindrical member comes into contact with an outer peripheral surface of the heat radiating member; and fixing the heat radiating member to the cylindrical member. .