JP2003021478A - Double pipe heat exchanger and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double pipe heat exchanger improved in workability of assembling and quality of product. SOLUTION: The double pipe heat exchanger 1 is constituted of an inner pipe 2 through which a medium to be cooled flows, an outer pipe 3 which is disposed enclosing the inner pipe 2 with a distance being given between itself and the outer periphery of the inner pipe 2, and a cross fin 4 which is disposed in the inner pipe 2 and has a substantially radial cross section. The inner pipe 2 is formed so as to have a portion 2a for disposing the cross fin 4, whose diameter is smaller than the peak diameter of the cross fin 4. The cross fin 4 is press fitted into the portion 2a.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a double-tube heat exchanger.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, an inner pipe 51 through which a medium to be cooled is circulated and an outer periphery of the inner pipe 51 are spaced apart from each other and surrounded by a circulation chamber for the cooling medium. A double-tube heat exchanger 50 including an outer pipe 53 that divides 52 and a radiation fin 54 that is fixedly installed inside the inner pipe 51 is disclosed in Japanese Unexamined Patent Publication No. 2000-2000.
No. 1446463.

Then, as shown in FIG.
4 is bent and formed in a gourd shape or petal shape in cross section, and a top end portion 54a of the outer periphery thereof is press-fitted and fixed to the inner wall surface of the inner pipe 51.

[0004]

In the above conventional heat exchanger, when the radiation fins 54 are press-fitted into the inner wall surface of the inner pipe 51, a press-fit flaw is generated on the inner wall surface of the inner pipe 51. Inner tube 51
Has a constant inner diameter in the tube axial direction, and the heat collecting fins 54 are press-fitted and moved inside the inner tube 51 over the entire area from the end of the inner tube 51 to the position where the heat radiation fins 54 are press-fitted and fixed. Therefore, that is, since the portion where the heat collecting fins 54 are not included is also included in the press-fitting section, the press-fitting distance becomes long, and debris due to the press-fitting scratches is accumulated on the inner wall surface of the inner pipe 51 in the traveling direction, increasing the press-fitting load. There is a problem that the scratch depth becomes large and the workability of assembly and the product quality are poor.

Therefore, the present invention solves the above-mentioned problems 2.
It is intended to provide a heavy pipe heat exchanger.

[0006]

In order to solve the above-mentioned problems, the first invention according to claim 1 is such that the inner pipe through which the medium to be cooled is circulated and the outer periphery of the inner pipe are separated and surrounded. In a double-pipe heat exchanger composed of an outer pipe provided and a cross fin arranged inside the inner pipe, first, a reduced diameter portion is formed in a region where the cross fin of the inner pipe is arranged, Next, the double fin heat exchanger is characterized in that the cross fin is press-fitted into the reduced diameter portion.

In the present invention, the press-fitting distance becomes the necessary minimum, and the press-fitting load can be reduced and the flaw depth can be reduced. Further, since the inner tube is reduced in diameter, the dimensional accuracy of the inner diameter of the inner tube is improved, and the adhesion between the inner tube and the cross fin, the brazing property, etc. are excellent. Further, since the tapered portion is formed with the diameter reduction, the tapered portion acts as a press-fitting guide, and the cross fin is smoothly pressed into the diameter reduced portion.

According to a second aspect of the present invention, an inner pipe for circulating the medium to be cooled, an outer pipe provided so as to surround the outer periphery of the inner pipe with a space therebetween, and an inner pipe are provided inside the inner pipe. In a double-pipe heat exchanger including a cross fin, a diameter reducing step of forming a diameter reducing portion in a region of the inner tube where the cross fin is disposed, and then the cross fin is press-fitted into the diameter reducing portion. The method of manufacturing a double-tube heat exchanger including a press-fitting step.

According to a third aspect of the present invention, an inner pipe through which the medium to be cooled is circulated, an outer pipe provided so as to surround the outer periphery of the inner pipe with a space therebetween, and an inner pipe are provided inside the inner pipe. In the double-pipe heat exchanger including the cross fins, the cross fins are arranged in a plurality of divisions in the axial direction of the inner pipe, and the plurality of cross fins are arranged in the region of the inner pipe where the cross fins are arranged. A double-tube heat treatment characterized in that a reduced diameter portion is formed, and a diameter reducing step of forming the reduced diameter portion and a step of press-fitting the cross fin into the reduced diameter portion are sequentially performed several times. It is an exchange.

In the present invention, the reduced diameter portion and the cross fins are arranged separately, so that the degree of freedom of the arrangement position of the cross fins is improved and tuning is facilitated.
Further, the bending of the inner and outer tubes is facilitated in the portion where the cross fins are not arranged, and after the heat exchanger is completed, the entire heat exchanger can be bent into a predetermined shape.

According to a fourth aspect of the present invention, an inner pipe through which a medium to be cooled is circulated, an outer pipe provided so as to surround the outer periphery of the inner pipe with a space therebetween, and an inner pipe are provided inside the inner pipe. In the double-pipe heat exchanger including the cross fins, the cross fins are arranged in a plurality of divisions in the axial direction of the inner pipe, and the plurality of cross fins are arranged in the region of the inner pipe where the cross fins are arranged. A double-tube heat treatment characterized in that a reduced diameter portion is formed, and a diameter reducing step of forming the reduced diameter portion and a step of press-fitting the cross fin into the reduced diameter portion are sequentially performed several times. It is a manufacturing method of an exchanger.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described based on an embodiment shown in FIGS.

1 to 3 show a first embodiment of the present invention. 1 is a side sectional view of the double-tube heat exchanger, and FIG.
2 is a sectional view taken along the line AA of FIG. FIG. 3 is a side sectional view of a process of assembling the inner tube and the cross fin of the double tube heat exchanger.

Double-tube heat exchanger 1 shown in FIGS. 1 and 2.
Is an inner pipe 2 through which the medium to be cooled flows, an outer pipe 3 provided so as to surround the outer periphery of the inner pipe 2 at a distance, and a cross fin having a substantially radial cross section disposed inside the inner pipe 2. 4 and. Both ends 3a of the outer pipe 3 are fixed to the outer peripheral surface of the inner pipe 2 by welding or the like, and a circulation chamber 5 in which a cooling medium is circulated is formed between the inner pipe 2 and the outer pipe 3. In the outer tube 3, an introduction tube 6 for introducing the cooling medium into the distribution chamber 5,
A discharge pipe 7 for discharging the cooling medium in the distribution chamber 5 is provided.

Inside the inner pipe 2, cross fins 4 having a substantially radial cross section are arranged. First, in the region of the inner pipe 2 where the cross fins 4 are arranged, the diameter of the crests of the cross fins 4 is determined. A reduced diameter portion 2a having a smaller diameter is formed, and then the cross fin 4 is press-fitted into the reduced diameter portion 2a.

The assembling process of the inner tube 2 and the cross fin 4 in the first embodiment of the present invention is shown in FIGS. An inner pipe 2 which is a metal pipe material shown in FIG. 3 (a) is prepared, and first, the inner pipe 2 is subjected to a diameter reducing step shown in FIG. 3 (b).
The reduced diameter portion 2a and the tapered portion 2b are formed in the region where the cross fins 4 are arranged. Although not shown, the diameter reducing step is performed by placing a split mold having a desired reduced diameter outside the inner tube 2 and pressurizing the split mold with a press. At this time, a cored bar may be arranged inside the inner tube. Alternatively, as another diameter reducing method, a spinning process or the like may be performed. Next, the cross fin 4 is press-fitted into the reduced diameter portion 2a by the press-fitting process shown in FIG. 3 (c). At this time, the tapered portion 2b acts as a press-fitting guide, and the cross fin 4 is smoothly press-fitted into the reduced diameter portion. As a pre-stage of the press-fitting process, brazing material is attached to the crests 4a of the cross fins 4 to be crimped onto the inner wall surface of the inner pipe 2, and after the press-fitting process, heating is performed to heat the inner pipe 2 and the cross fins 4 together. It may be attached and fixed.

FIG. 4 and FIG. 5 show a second embodiment of the present invention. FIG. 4 is a side sectional view of a double-pipe heat exchanger in which the reduced diameter portion and the cross fins are formed and arranged by being divided into a plurality of pieces in the axial direction of the inner tube. FIG. 5 is a side sectional view of a process of assembling the inner pipe and the plurality of cross fins of the double pipe heat exchanger.

The double-tube heat exchanger 10 shown in FIG. 4 has an inner tube 2 for circulating a medium to be cooled, an outer tube 3 provided so as to surround the outer circumference of the inner tube 2 at a distance, and an inner tube. A plurality of cross fins 4a having a substantially radial cross section disposed inside
It is composed of b and 4c. Both ends 3a of the outer pipe 3 are fixed to the outer peripheral surface of the inner pipe 2 by welding or the like, and a circulation chamber 5 in which a cooling medium is circulated is formed between the inner pipe 2 and the outer pipe 3. The outer pipe 3 is provided with an introduction pipe 6 for introducing the cooling medium into the distribution chamber and a discharge pipe 7 for discharging the cooling medium in the distribution chamber.

Inside the inner tube 2, a plurality of cross fins 4a, 4b, 4c having a substantially radial cross section are arranged.
Reduced diameter portions 8a, 8b, 8c having a diameter smaller than the peak diameter of the cross fins 4a, 4b, 4c are formed in the region of the inner tube 2 where the cross fins 4 are arranged.
The cross fins 4a, 4b, 4c are press-fitted into b, 8c. The region 9 of the inner pipe 2 where the cross fins 4a, 4b, 4c are not arranged is in the state of the pipe material diameter without being subjected to the diameter reduction processing.

FIG. 5 shows a process of assembling the inner tube 2 and the cross fins 4a, 4b, 4c in the second embodiment of the present invention.
An inner tube 2 which is a metallic tube material shown in FIG. 5 (a) is prepared, and first, a first diameter reducing portion 8a is formed by a diameter reducing step shown in FIG. 5 (b). Next, the first cross fin 4a is press-fitted into the first reduced diameter portion 8a by the press-fitting process shown in FIG. 5 (c). Next, the second reduced diameter portion 8b is formed by the diameter reduction process shown in FIG. Next, the second cross fin 4b is press-fitted into the second reduced diameter portion 8b by the press-fitting process shown in FIG. 5 (e). Next, the third diameter-reduced portion 8c is formed by the diameter reduction step shown in FIG. Next, the third cross fin 4c is press-fitted into the third reduced diameter portion 8c by the press-fitting process shown in FIG. 5 (g). As described above, the inner tube 2 and the plurality of cross fins are formed by sequentially performing the diameter reducing step of forming the diameter reducing portions 8a, 8b, 8c and the step of press-fitting the cross fins 4a, 4b, 4c. 4a, 4b, and 4c are assembled.

According to this assembling step, the region 9 of the inner tube 2 where the cross fins 4a, 4b, 4c are not arranged is not press-fitted but is passed through, so that there is a problem that the press-fitting load increases and the flaw depth increases. Will be resolved.

Incidentally, although not shown, it is possible to form the first to third reduced diameter portions first and then press fit the first to third cross fins in another assembling step. In this case, the inner diameter of at least one of the first reduced diameter portion 8a and the third reduced diameter portion 8c is formed larger than the peak portion diameter of the second cross fin 4b. Then, after the second cross fins 4b are not press-fitted but passed through from the side of the reduced diameter portion having a large inner diameter, the second cross fins 4b are passed through the second reduced diameter portion 8b.
Is pressed into. In this way, the second cross fin 4b
The press-fitting step (e) is performed without extra scratches on the first or third reduced-diameter portion and without any extra press-fitting load. Incidentally, the cross fins press-fitted into the diameter-reduced portion having a large inner diameter have a peak diameter larger than the peak diameter of the second cross fin 4b, and are press-fitted into the corresponding diameter-reduced portions.

FIG. 6 shows an application of the double pipe heat exchanger of the present invention to an EGR pipe of an automobile. An exhaust manifold of an internal combustion engine (not shown) is connected to an upstream side 2x of the inner pipe 2, and an intake manifold (not shown) is connected to a downstream side 2y of the inner pipe 2 so that exhaust gas flows through the inner pipe 2 as indicated by an arrow. . For example, engine cooling water is used as the cooling medium, and the cooling medium introduced through the introduction pipe 6 flows through the circulation chamber 5 and is discharged through the discharge pipe 7.

[0024]

As described above, according to the first and second aspects of the present invention, the press-fitting distance becomes the necessary minimum, and the press-fitting load and the flaw depth can be reduced. Further, since the inner tube is reduced in diameter, the dimensional accuracy of the inner diameter of the inner tube is improved, and the adhesion between the inner tube and the cross fin, the brazing property, etc. are excellent. Further, since the tapered portion is formed with the diameter reduction, the tapered portion acts as a press-fitting guide, and the cross fin is smoothly pressed into the diameter reduced portion.

According to the third and fourth aspects of the present invention, since the reduced diameter portion and the cross fins are arranged separately, the degree of freedom in the arrangement position of the cross fins is improved,
Tuning becomes easy. Further, the bending of the inner and outer tubes is facilitated in the portion where the cross fins are not arranged, and after the heat exchanger is completed, the entire heat exchanger can be bent into a predetermined shape.

[0026]

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first embodiment of the present invention.

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

FIG. 3 is a side sectional view of an assembling process of the inner tube and the cross fin in the first embodiment of the present invention.

FIG. 4 is a side sectional view showing a second embodiment of the present invention.

FIG. 5 is a side sectional view of an assembling process of the inner tube and the cross fin in the second embodiment of the present invention.

FIG. 6 is a side view of the present invention applied to an EGR pipe of an automobile.

FIG. 7 is a side sectional view showing a conventional double-tube heat exchanger.

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

[Explanation of symbols]

1,10 Double tube heat exchanger 2 inner tube 2a reduced diameter part 2b taper 3 outer tube 4,4a, 4b, 4c Cross fin 8a, 8b, 8c Reduced diameter part

Claims (4)

[Claims] 1. A double pipe comprising an inner pipe through which a medium to be cooled flows, an outer pipe provided so as to surround the outer periphery of the inner pipe with a space therebetween, and a cross fin arranged inside the inner pipe. In the double heat exchanger, a reduced diameter portion is first formed in a region of the inner tube where the cross fin is arranged, and then the cross fin is press-fitted into the reduced diameter portion. Exchanger. 2. A double pipe comprising an inner pipe through which a medium to be cooled is circulated, an outer pipe provided so as to surround the outer periphery of the inner pipe at a distance from each other, and a cross fin arranged inside the inner pipe. Type heat exchanger, a double pipe comprising a diameter reducing step of forming a diameter reducing portion in a region of the inner tube where the cross fins are disposed, and then a press fitting step of press-fitting the cross fin into the diameter reducing portion. Type heat exchanger manufacturing method. 3. A double pipe composed of an inner pipe through which a medium to be cooled is circulated, an outer pipe provided so as to surround the outer periphery of the inner pipe with a space therebetween, and a cross fin arranged inside the inner pipe. In the heat exchanger of the type described above, the cross fins are divided into a plurality of parts in the axial direction of the inner pipe, and a plurality of reduced diameter portions are formed in a region of the inner pipe where the cross fins are arranged. A double-tube heat exchanger characterized in that a diameter reducing step of forming a diameter portion and a step of press-fitting the cross fin into the diameter reducing portion are sequentially performed several times. 4. A double pipe comprising an inner pipe through which a medium to be cooled flows, an outer pipe provided so as to surround the outer periphery of the inner pipe with a space therebetween, and a cross fin arranged inside the inner pipe. In the heat exchanger of the type described above, the cross fins are divided into a plurality of parts in the axial direction of the inner pipe, and a plurality of reduced diameter portions are formed in a region of the inner pipe where the cross fins are arranged. A method of manufacturing a double-tube heat exchanger, characterized in that a diameter reducing step of forming a diameter portion and a step of press-fitting the cross fin into the diameter reducing portion are sequentially performed several times.