JPH10232097A - Heat-exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance assembling workability, durability and reliability. SOLUTION: A header pipe 14 constituting a heat-exchanger comprises a tank body 15 and a plate 16 being divided into two in the direction for inserting a heating tube 2 and brazed each other after being assembled. The plate 16 has a hole 11a for inserting one end of the heating tube 2. A pair of bent parts 20, 20 are formed at the fringe part of opening of the tank body 15 such that they can be abutted against a part thereof. A pair of wall parts 17, 17 to be fitted tightly over the bent parts 20, 20 and step parts 18, 18 abutting against the bent parts 20, 20 are provided at the end fringe part of the plate 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a heat exchanger used as a condenser or the like constituting an air conditioner of an automobile.

[Prior art]

2. Description of the Related Art A heat exchanger having a structure as shown in FIG. 8 is conventionally known as a heat exchanger used as a condenser of an air conditioner of a vehicle. The heat exchanger 1 has a core portion 4 including a plurality of heat transfer tubes 2 and 2 and fins 3 and 3 and a pair of heat transfer tubes 2 and 2 forming the core portion 4 each having one end penetrating therethrough. Header pipes 5a and 5b. Then, the pair of header pipes 5a,
An inlet pipe 6 and an outlet pipe 7 are provided on both upper and lower side surfaces of one of the header pipes 5a (the left side in FIG. 8) among the header pipes 5b. Further, a partition plate 8 for densely partitioning the inside of the one header pipe 5a is provided at an intermediate portion inside the one header pipe 5a. The above header pipes 5a,
The upper and lower ends of 5b are tightly closed by lid plates 13, 13. These constituent members of the heat exchanger 1 are made of an aluminum alloy, and are joined together by brazing in a combined state. A pair of side plates 9 and 9 are provided above and below the core portion 4 and between the pair of header pipes 5a and 5b to reinforce the upper and lower end edges of the core portion 4. The connection strength between the pair of header pipes 5a and 5b is secured.

[0003] The heat exchanger 1 configured as described above operates as follows. That is, the fluid such as the refrigerant sent from the inlet pipe 6 to the upper inside of the one header pipe 5a is:
Through the heat transfer tubes 2 and 2 in the upper half of the core portion 4 of the heat transfer tubes 2 and 2, toward the other header pipe 5b (right side in FIG. 8) of the pair of header pipes 5a and 5b. Flows. Then, the fluid turned back in the header pipe 5b flows toward the lower part inside the one header pipe 5a through the heat transfer tubes 2 and 2 in the lower half of the core portion 4 of the heat transfer tubes 2 and 2. It is sent out from the outlet pipe 7.
In this way, the fluid such as the refrigerant flowing through the many heat transfer tubes 2, 2 exchanges heat with the air flowing around the heat transfer tubes 2, 2 and the fins 3, 3.

However, when assembling the heat exchanger 1 configured and operating as described above, there are the following problems. That is, when connecting the heat transfer tubes 2 and 2 constituting the heat exchanger 1 and the header pipe 5a (5b),
As shown in (1), it is necessary to insert a positioning member such as the metal core 10 into each of the header pipes 5a (5b). Then, in this state, the ends of the heat transfer tubes 2 and 2 are inserted into the plurality of insertion holes 11 and 11 provided in the header pipe 5a, and together with other components constituting the heat exchanger 1 in a heating furnace. Braze together. Thereby, the heat transfer tubes 2 and 2 are connected to the header pipe 5 together with the other constituent members.
a (5b). For this purpose, a brazing material is laminated on the surface of at least one of the constituent members to be brazed and joined. In this way, the core metal 1
0 for the header pipe 5a (5
The reason why the heat transfer tubes 2 and 2 are inserted inside the header pipe 5a (5b) is that the ends of the heat transfer tubes 2 and 2 protrude too much inside the header pipe 5a (5b) and the resistance to the fluid flowing inside the header pipe 5a (5b). This is to prevent the performance of the heat exchanger 1 from deteriorating. However, the work of inserting the core metal 10 into the inside of the header pipe 5a (5b) is troublesome, and complicates the assembly work of the heat exchanger.

Further, when the partition plate 8 is provided in the inside like the one header pipe 5a, there are the following problems. That is, as shown in FIG. 10, after inserting the partition plate 8 through the notch 12 provided in the one header pipe 5a, the heat transfer tube 2 is inserted into the insertion holes 11 provided in the one header pipe 5a. In the case of inserting the end portions of the two cores, two cores 10 are required as shown in FIG. Therefore, the assembly work of the heat exchanger is further complicated.

Since the metal core 10 is inserted from both ends of the header pipe 5a, two or more partition plates 8 cannot be provided on the header pipe 5a. The reason for this is that, when two or more of the partition plates 8 are provided inside the one header pipe 5a, the portion between the partition plates 8 inside the one header pipe 5a is provided with the one header plate. A core bar 10 for regulating the length of the end of the heat transfer tubes 2 inserted into the pipe 5a.
This is because such members cannot be provided. Accordingly, the partition plate 8 is provided inside the header pipe 5a (5a), and the fluid flowing through the heat transfer tubes 2, 2 moves zigzag between the pair of header pipes 5a, 5b.
In the case of a so-called multi-flow type, the return of the fluid cannot be made at three or more locations (so-called four passes). For this reason, by increasing the number of turns, the flow path of the fluid flowing through the heat transfer tubes 2 and 2 is lengthened, and it is not possible to further improve the performance of the heat exchanger.

As shown in FIG. 9 described above, after one core 10 is inserted into the header pipe 5a (5b) in advance, the ends of the heat transfer tubes 2, 2 are connected to the plurality of heat pipes. Insertion hole 1
A method is also conceivable in which the partition plate 8 is inserted and brazed together with the other components of the heat exchanger except for the partition plate 8, and then the partition plate 8 is inserted and brazed. However, such a method requires two brazing operations,
Not only does the manufacturing cost of the heat exchanger become high, but also the reliability of the brazed portion and the corrosion resistance of the header pipes 5a (5b) and the heat transfer tubes 2, 2 cannot be sufficiently ensured.

In order to solve the above-mentioned problems, Japanese Utility Model Application Laid-Open No.
JP-A-109185 and JP-A-4-63986 describe inventions in which the structure of a header pipe constituting a heat exchanger is devised. Each of the header pipes described in each of these publications has a so-called two-piece integrated structure formed by combining a tank body and a plate. In addition, the same number of insertion holes as the heat transfer tubes into which one ends of the plurality of heat transfer tubes are inserted are formed in the plates. Then, the end of the heat transfer tube inserted into the inside of each of the header pipes is brought into contact with the tank body, or the inclined surface formed on the plate, or the stepped portion, so that the end of the heat transfer tube is formed as described above. The length protruding inside the header pipe is restricted to a minimum.

[0009]

However, in the case of the conventional header pipe structure described in each of these publications, the joining portion for brazing and joining the tank body and the plate constituting each of the header pipes is formed by the above-mentioned plate. Is merely abutted against a stepped portion formed by bending the opening edge of the tank body against the straight edge of the tank. Therefore, the brazing area between the tank body and the plate is not sufficient. And this shortage of the brazing area causes a decrease in durability and reliability of the heat exchanger. The heat exchanger according to the present invention is capable of reducing the trouble of inserting a member such as a metal core into the inside of the header pipe when connecting the end portion of the heat transfer tube to the header pipe in order to solve any of the above problems. The present invention has been devised to realize a structure capable of securing a brazing area between constituent members constituting the header pipe, as well as being omitted.

[0010]

The heat exchanger of the present invention has a core portion comprising a plurality of heat transfer tubes and fins, and a plurality of core portions constituting the core portion, similarly to the above-mentioned conventional heat exchanger. And a pair of header pipes each having one end of the heat transfer tube.

Particularly, in the heat exchanger of the present invention, claim 1
In each of the heat exchangers described above, each of the header pipes is composed of a tank body and a plate which are divided into two in the insertion direction of each of the heat transfer tubes and brazed to each other in an assembled state. The plate has the same number of insertion holes as the heat transfer tubes into which one end of each of the heat transfer tubes can be inserted. Further, a pair of bent portions capable of abutting a part of an edge of each of the heat transfer tubes on an opening edge of one of the tank body and the plate is formed on an edge of the other member. The above-mentioned bent portion is fitted to the inside thereof without play.
A pair of wall portions and a step portion that abuts the bent portion are formed.

Further, in the heat exchanger according to claim 2, each of the header pipes is divided into two in the insertion direction of each of the heat transfer tubes, and the tank body and the outer body are brazed to each other in an assembled state. A plate and an inner plate sandwiched between the tank body and the outer plate and having a through hole formed in a portion facing the end of each of the heat transfer tubes. And the outer plate of these is
The heat transfer tubes have the same number of insertion holes into which one end of each heat transfer tube can be inserted. Further, a part of an end edge of each of the heat transfer tubes is abutted on a peripheral portion of the through hole on a part of one surface of the inner plate. Further, a pair of steps for abutting the inner plate on an opening edge of one of the tank body and the outer plate, and an opening of the other member of the tank body and the outer plate. A pair of walls are formed to fit the outer surface of the edge portion and the inner plate to the inside without play.

[0013]

According to the heat exchanger of the present invention configured as described above,
In the heat exchanger according to the first aspect, the header pipe constituting the heat exchanger has a so-called two-piece integrated structure including a tank body and a plate. Since a pair of bent portions is formed at the opening edge of one of the members, a part of the edge of the heat transfer tube into which the end is inserted from the insertion hole can be brought into contact with the bent portion. Therefore, when assembling the heat exchanger, when connecting the end of the heat transfer tube to the header pipe, it is possible to omit the trouble of inserting a positioning member such as a core metal into the inside of the header pipe. it can. Therefore,
The workability of assembling the heat exchanger can be improved.

Further, the pair of bent portions also contributes to improving the brazing property between the tank body and the plate constituting the header pipe. That is, the bent portion is fitted without looseness inside a pair of walls formed on the edge of the other member of the tank body and the plate, and the edge of the other member is also fitted. The bent portion abuts against a pair of steps formed in the portion. Therefore, the bent portion not only restricts the length of the end of the heat transfer tube protruding inside the header pipe to a minimum, but also secures a brazing area between the tank body and the plate constituting the header pipe. Also contributes. In this way, the heat exchanger of the present invention can improve the durability and reliability as well as the workability of assembling the heat exchanger.

Further, in the heat exchanger according to the second aspect, the header pipe constituting the heat exchanger is sandwiched between the tank body and the outer plate, and between the tank body and the outer plate. It consists of an inner plate and a hole is formed in this inner plate,
A part of the edge of the heat transfer tube can be abutted against a peripheral portion of the through hole on a part of one surface of the inner plate.
Therefore, also in this heat exchanger, the workability of assembling the heat exchanger can be improved similarly to the heat exchanger according to the first aspect. Further, a pair of steps and a wall formed at an opening edge of one of the tank body and the outer plate are connected to the opening of the other member of the tank body and the outer plate, respectively. By contacting the outer surface of the end portion and the inner plate, the brazing property between the tank body, the outer plate and the inner plate can be improved. As described above, also in the heat exchanger according to the second aspect, it is possible to improve the durability and reliability as well as the workability of assembling the heat exchanger.

[0016]

1 to 3 show a first embodiment of the present invention corresponding to claim 1. FIG. The feature of the present invention is to improve the assembling workability when connecting the end of the heat transfer tube 2 to the header pipe 14 when assembling the heat exchanger, and to make the components constituting the header pipe 14 together. In the header pipe structure that can secure the brazing area. Since the structure and operation of the other parts are the same as those of the conventional structure shown in FIG. 8 described above, overlapping illustration and description of the equivalent parts will be omitted or simplified, and the following description will focus on the characteristic parts of the present invention. .

As shown in FIG. 2, the header pipe 14 is divided into two parts in the insertion direction of the heat transfer tube 2, and is composed of a tank body 15 and a plate 16 which are brazed to each other in an assembled state. The plate 16 is formed in a substantially semi-cylindrical shape, and a pair of mutually parallel walls 17 and 17 and steps 18 and 18 are formed by bending both ends of the opening. Then, the wall portions 17 and 1 of the plate 16
7 and a plurality of insertion holes 11a, 11a for inserting the heat transfer tube 2 into the semi-cylindrical portion 19 where the step portions 18, 18 are not formed.
Is formed. The tank main body 15 is also formed in a substantially semi-cylindrical shape, and both end edges of the opening are formed by bending in directions approaching each other to form a pair of bent portions 20. The pair of bent portions 20, 20 are on the same plane with each other, and in a state where the heat transfer tube 2 is inserted by combining the tank body 15 and the plate 16, with respect to the insertion direction of the heat transfer tube 2. It exists in the vertical direction. Then, with the tank body 15 and the plate 16 combined, the tank body 1
The bent portions 20, 5 are fitted into the pair of walls 17, 17 formed on the plate 16 without looseness, and the pair of steps 1, formed on the plate 16.
8 and 18 with almost no gap.

Further, in the case of this embodiment, a partition plate 21 having a shape as shown in FIG. 1 is provided to densely partition the inside of the header pipe 14. The partition plate 21 is inserted into the inside of the tank body 15 through cutouts 22 formed in the bent portions 20 of the tank body 15, and the outer periphery of the large-diameter semicircular arc portion 23 of the partition plate 21 is inserted. The surface and the inner peripheral surface of the tank body 15 are brought into close contact with each other. The projection 24 formed on the partition plate 21 is engaged with a locking hole 25 formed on the inner peripheral surface of the tank body 15 so that the partition plate 21 is connected to the tank body 1.
5 is provided for reliable positioning inside.
In this state, the tank main body is brought into close contact with the outer peripheral surface of the semicircular portion 26 on the small diameter side of the partition plate 21 and the inner peripheral surface of the semi-cylindrical portion 19 constituting the plate 16. 15 and plate 16 are combined as described above. Then, the tank body 15 and the plate 16 are temporarily assembled by caulking at least one pair of caulking portions 27 formed on the wall portions 17, 17 on the inner side in the width direction of the plate 16, and the header pipe is formed. 14. Note that the opening at both ends of the header pipe 14 configured in this manner is closed tightly by a pair of lid plates (not shown).

Through the plurality of insertion holes 11a, 11a formed in the header pipe 14 thus temporarily assembled,
The end of the heat transfer tube 2 is inserted inside the header pipe 14. Then, as shown in FIG. 2, a part of the edge of the heat transfer tube 2 is abutted against one surface (the lower surface in FIG. 2) of the pair of bent portions 20, 20. In this case, the end opening of the heat transfer tube 2 is not blocked by the pair of bent portions 20. For this reason, the interval a between the edges of the pair of bent portions 20, 20 is
The width is slightly smaller than the width b of the heat transfer tube 2 (a <b). The constituent members combined in this way are heated together with other constituent members constituting the heat exchanger in a heating furnace, and are integrally joined by brazing. Brazing for brazing,
It is laminated on at least one of the members abutting each other.

The heat exchanger of the present invention configured as described above has the following features.
When connecting the end of the heat transfer tube 2 to the header pipe 14 to assemble the heat exchanger, the core metal 10 (FIGS.
1) and the like for the header pipe 14.
It is possible to save the trouble of inserting into the inside of the device. The reason is that when the end of the heat transfer tube 2 is inserted into the inside of the header pipe 14, a part of the end of the heat transfer tube 2 is formed at the opening end of the tank body 15 constituting the header pipe 14. This is because the length of the end of the heat transfer tube 2 protruding inside the header pipe 14 can be regulated by abutting the pair of bent portions 20, 20. Therefore, the heat exchanger of the present invention can improve the assembly workability.

Further, the pair of bent portions 20, 20
Contributes to the improvement of the brazing property between the tank body 15 and the plate 16 constituting the header pipe 14. That is, a joining portion for brazing the tank body 15 and the plate 16 is composed of a pair of bent portions 20 and 20 formed on the tank body 15 and the bent portions 2.
The edge of the semi-cylindrical portion 28 continuous with 0, 20 and the pair of steps 18, 18 and the wall 1 formed on the plate 16
7 and 17 are contact portions. Therefore, the pair of bent portions 20, 20 not only regulates the length of the end of the heat transfer tube 2 protruding inside the header pipe 14, but also the components 15, 16 of these header pipes 14. These components 1 contribute to securing the brazing area.
It is possible to improve the brazing property between 5, 16 pieces. Like this
ADVANTAGE OF THE INVENTION This invention can achieve both the improvement of the assembly workability of a heat exchanger, and the improvement of durability and reliability.

As described above, since the header pipe 14 constituting the heat exchanger of the present invention has a structure in which the tank body 15 and the plate 16 divided into two are combined, a part of the header pipe 14 is used. The inlet pipe 6 or the outlet pipe 7 (see FIG. 8) to be attached can be firmly attached. That is, as shown in FIG. 3, the end of the inlet pipe 6 (outlet pipe 7) having the caulking portion 30 formed near the end thereof is inserted through the through hole 29 provided in a part of the tank main body 15 to the tank. Insert from outside of the body 15. Then, the end of the inlet pipe 6 (outlet pipe 7) is crushed from the inside of the tank body 15 using a jig or the like, so that another caulking portion 31 is formed.
To form By clamping a part of the inlet pipe 6 (outlet pipe 7) by the caulking portions 30 and 31,
The inlet pipe 6 (outlet pipe 7) can be firmly fixed to the tank body 15. The inlet pipe 6 (outlet pipe 7) fixed to the tank body 15 in this manner and the tank body 1
The contact portion with 5 is sealed by brazing.

The semi-cylindrical portion 28 which is continuous with the pair of bent portions 20 and 20 formed on the tank body 15 is preferably provided with a pair of walls formed at the open edges of the plate 16 if possible. It is more preferable to form them so as to be parallel to the parts 17 and 17 from the viewpoint of securing the brazing area between the tank body 15 and the plate 16.

Next, FIGS. 4 and 5 show a second example of the embodiment of the present invention corresponding to claim 1, as in the first example described above. In the case of the header pipe 14a of the present example, unlike the header pipe 14 of the above-described first example (FIGS. 1 and 2), a part of the edge of the heat transfer tube 2 is brought into contact with the opening edge of the plate 16a. Are formed. A pair of wall portions 33, 33 for fitting the pair of bent portions 32, 32 to the inside of the opening edge of the tank body 15a without looseness, and the pair of bent portions. Step 3 for abutting 32, 32
4 and 34 are formed. A partition plate 21a for densely partitioning the inside of the header pipe 14a is provided with cutouts 22 formed in the bent portions 32 of the plate 16a.
a and 22a and inserted into the inside of the plate 16a. In the case of this example, the tank body 15a is made by integral extrusion of an aluminum alloy. Therefore, no brazing material can be laminated on the side of the tank body 15a. Therefore, all brazing materials necessary for brazing are stacked on the side of the plate 16a and the partition plate 21a. In order to engage the projection 24 of the partition plate 21a, a locking recess 40 is formed on the inner peripheral surface of the tank body 15a. Other configurations and operations are the same as those of the above-described first example, and therefore, the same parts are denoted by the same reference numerals, and redundant description will be omitted.

Next, FIGS. 6 and 7 correspond to claim 2.
13 shows a third example of the embodiment of the present invention. In the case of the present example, the header pipe 14b constituting the heat exchanger is sandwiched between the tank body 35 and the outer plate 36, and between the tank body 35 and the outer plate 36, and faces the end of each heat transfer tube 2. And an inner plate 37 in which a through hole 38 is formed. Since the outer plate 36 has the same shape as the plate 16 constituting the header pipe 14 of the first example shown in FIGS. 1 and 2 described above, a detailed description of the outer plate 36 will be omitted. The tank main body 35 and the inner plate 37 together correspond to the tank main body 15 (FIGS. 1 to 3) constituting the header pipe 14 of the first example. That is, the tank body 35 constituting the header pipe 14b of this example is formed in a simple semi-cylindrical shape, and the inner plate 37 sandwiched between the tank body 35 and the outer plate 36 is connected to other constituent members. It is also formed by a flat plate made of an aluminum alloy. The through holes 38 are formed so as to penetrate both sides of the inner plate 37. The notches 39, 39 provided in the through holes 38 are provided for positioning the partition plate 21.

The header pipe 1 of the present embodiment configured as described above
The constituent members of 4b are combined as shown in FIG. 7, and are integrally connected to other constituent members of the heat exchanger by brazing. In the case of this example, since a part of the end of the heat transfer tube 2 can be abutted against the peripheral portion of the through hole 38, the length of the end of the heat transfer tube 2 protruding inside the header pipe 14b is regulated. it can. Further, a pair of steps 18, 18 and a wall 17, formed on the opening edge of the outer plate 36,
17 are in contact with the edge of the inner plate 37 and the outer side surface of the opening edge of the tank body 35, respectively.
It is possible to improve the brazing property between 5, 36, and 37. Other configurations and operations are the same as those of the first example described above, and therefore, the same parts are denoted by the same reference numerals, and overlapping description and illustration are omitted.

It should be noted that the capacitor of the present invention is not limited to the third type described above.
Contrary to the example, a step portion and a wall portion may be formed at the opening edge of the tank body constituting the header pipe, and the outer plate may be formed in a simple semi-cylindrical shape. Then, as in the structure of the third example described above, the inner plate 37 is sandwiched between the tank body and the outer plate.

[0028]

Since the heat exchanger of the present invention is constructed and operates as described above, the workability of assembling the heat exchanger can be improved.
Improvements in durability and reliability can also be realized.

[Brief description of the drawings]

FIG. 1 is a partially exploded perspective view of a header pipe, showing a first example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the header pipe showing a state where a heat transfer tube is inserted into the header pipe.

FIG. 3 is a cross-sectional view showing a state in which a tank main body constituting the header pipe is taken out and an inlet pipe (outlet pipe) is connected.

FIG. 4 is a partially exploded perspective view of a header pipe, showing a second example of the embodiment of the present invention.

FIG. 5 is a view similar to FIG. 2;

FIG. 6 is a partially exploded perspective view of a tank body and an inner plate constituting a header pipe, showing a third example of the embodiment of the present invention.

FIG. 7 is a view similar to FIG. 2;

FIG. 8 is a schematic perspective view showing an example of a conventional heat exchanger.

FIG. 9 is a cross-sectional view taken along the line AA of FIG. 8, showing an assembled state of the header pipe and the heat transfer tube in a conventional structure without a partition plate.

FIG. 10 is a perspective view showing a state in which a partition plate is inserted into a header pipe in a conventional structure.

FIG. 11 shows a case where a partition plate is installed on a header pipe.
The figure similar to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat exchanger 2 Heat transfer tube 3 Fin 4 Core part 5a, 5b Header pipe 6 Inlet pipe 7 Outlet pipe 8 Partition plate 9 Side plate 10 Core metal 11, 11a Insertion hole 12 Notch 13 Cover plate 14, 14a, 14b Header pipe 15, 15a Tank body 16, 16a Plate 17 Wall 18 Step 19 Semi-cylindrical part 20 Bend 21, 21a Partition plate 22, 22a Notch 23 Large-diameter half-arc 24 Projection 25 Locking hole 26 Small-diameter half Circular part 27 Caulked part 28 Semi-cylindrical part 29 Through hole 30 Caulked part 31 Caulked part 32 Bent part 33 Wall part 34 Step part 35 Tank body 36 Outer plate 37 Inner plate 38 Through hole 39 Notch 40 Locking recess

Claims (2)

[Claims] 1. A heat exchanger comprising: a core portion including a plurality of heat transfer tubes and fins; and a pair of header pipes each having one end of each of the plurality of heat transfer tubes constituting the core portion. Each of the header pipes is divided into two in the insertion direction of each of the heat transfer tubes, and is composed of a tank body and a plate which are brazed to each other in an assembled state, of which one end of each of the heat transfer tubes is inserted. Free,
A pair of bent portions having the same number of insertion holes as those of the heat transfer tubes and capable of abutting a part of the edge of each of the heat transfer tubes to the opening edge of one of the tank body and the plate. A pair of wall portions for fitting the bent portion to the edge of the other member without looseness inside thereof, and a step portion for abutting the bent portion, respectively. Heat exchanger. 2. A heat exchanger comprising: a core portion comprising a plurality of heat transfer tubes and fins; and a pair of header pipes through which one end of each of the plurality of heat transfer tubes constitutes the core portion. The header pipe is divided into two in the insertion direction of the heat transfer tubes, and the tank body and the outer plate are brazed to each other in an assembled state,
An inner plate sandwiched between the tank body and the outer plate and having a through hole formed at a portion facing the end of each of the heat transfer tubes, of which the outer plate is inserted with one end of each of the heat transfer tubes. Freely, it has the same number of insertion holes as these heat transfer tubes, and a part of one end of the inner plate abuts a part of an edge of each of the heat transfer tubes to a peripheral portion of the through hole, and the tank body and A pair of steps for abutting the inner plate against an opening edge of one of the outer plate and an outer surface of an opening edge of the other member of the tank body and the outer plate; And a pair of walls for fitting the inner plate to the inner plate without play.