JPH04288493A - Manufacture of heat exchanger made of aluminum - Google Patents

Abstract

PURPOSE:To improve the brazing property of heat transfer tubes to a tank while securing the convenient property of assembling work. CONSTITUTION:Polybutene is applied at least, one of the inner peripheral rims of through holes 7, 7, formed on a tank 4 or the outer peripheral surface of the ends of heat transfer tubes 5, 5 at first. Subsequently, the ends of respective heat transfer tubes 5, 5 are inserted into the through holes 7, 7, to braze them after heating thereafter. Polybutene sublimes at a temperature lower than a brazing temperature and residue does not remain whereby faulty brazing will never be caused and the yield of products is improved.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The method for manufacturing an aluminum heat exchanger according to the present invention is utilized, for example, in manufacturing condensers and heater cores of automobile air conditioners, or radiators for cooling water heat radiation.

0002

2. Description of the Related Art In recent years, heat exchangers such as condensers and heater cores constituting automobile air conditioners, or radiators for dissipating cooling water heat are increasingly being made of lightweight aluminum alloys.

FIGS. 1 and 2 show an example of an aluminum heat exchanger used as a condenser for refrigerant condensation in air conditioners among such heat exchangers.
This shows what was disclosed in Publication No. 4874.

This conventional aluminum heat exchanger has an inlet side tank 2 connected to an inlet pipe 1 and an outlet side tank 4 connected to an outlet pipe 3 arranged parallel to each other, and both tanks 2 and 4 are arranged parallel to each other. are connected to each other by a plurality of heat transfer tubes 5, 5, and corrugated fins 6, 6 are sandwiched between adjacent heat transfer tubes 5, 5.

When a high-temperature, high-pressure refrigerant discharged from a compressor is to be cooled and condensed by the aluminum heat exchanger constructed in this manner, the high-temperature, high-pressure refrigerant is sent into the inlet side tank 2 through the inlet pipe 1.

[0006] The refrigerant sent into the inlet side tank 2 is
The refrigerant is then sent to the outlet tank 4 through the plurality of heat transfer tubes 5, 5, during which time the refrigerant exchanges heat with the air flowing between the adjacent heat transfer tubes 5, 5, and is cooled and condensed. . The resulting liquid refrigerant is transferred to the outlet side tank 4
It is taken out from the outlet pipe 3 through the outlet pipe 3 and sent to an evaporator (not shown).

By the way, when manufacturing an aluminum heat exchanger constructed and operated as described above, each of the constituent members 1 to 6 is assembled in the state shown in FIG.
Braze the 6 pieces together.

For example, the ends and outlet sides of each heat exchanger tube 5, 5,
As shown in FIG. 3, the joint between the two tanks 2 and 4 on the inlet side is formed by inserting the end of the heat transfer tube 5 into the through hole 7 formed in the tank 4 (2), and by inserting the end of the heat transfer tube 5 into the inner peripheral edge of the through hole 7. and the outer peripheral surface of the end of the heat transfer tube 5 are liquid-tightly brazed.

[0009] These operations are automatically performed at the factory, but the ends of each heat transfer tube 5, 5 are connected to each tank 4 (2).
In order to smoothly insert the heat exchanger tubes into the through holes 7, 7 formed in the above, apply lubricating oil to the outer peripheral surface of the end of each heat exchanger tube 5, 5 or the inner peripheral edge of each through hole 7, 7 prior to the insertion work. Painting is being done.

That is, so as not to create a large gap between the outer peripheral surface of the end of each heat exchanger tube 5, 5 and the inner peripheral edge of each through hole 7, 7,
The size of each through hole 7, 7 is made to substantially match the outer peripheral shape of each heat exchanger tube 5, 5. Further, in the automated assembly operation, all the heat exchanger tubes 5, 5 are inserted into the respective through holes 7, 7 at the same time. For this reason, by applying lubricant as mentioned above,
This makes it easier to insert the heat exchanger tubes 5, 5 into the respective through holes 7, 7.

[0011]

[Problems to be Solved by the Invention] However, the lubricating oil applied to the insertion portion is carbonized during the heat brazing operation that is performed following the insertion operation, and the lubricating oil remains on the outer circumferential surface of the end of the heat exchanger tubes 5, 5. The heat exchanger tube 5 remains between the through holes 7 and the inner peripheral edge of the 7.
, 5 and the through holes 7, 7 are likely to be defective, which is undesirable from the viewpoint of improving product yield.

[0012] Japanese Utility Model Application No. 62-166483 discloses that, as shown in FIG. A structure is described in which packing 9 is interposed to maintain liquid tightness between the outer circumferential surface of the end portion of heat transfer tube 5 and the inner circumferential edge of through hole 7 without brazing.

However, in the case of such a structure, not only does the cost increase due to the use of the packing 9, but also it is difficult to compress the packing 9 sufficiently when the heat transfer tube 5 is a flat tube. , cannot be hired.

The method of manufacturing an aluminum heat exchanger of the present invention eliminates the above-mentioned disadvantages.

[0015]

[Means for Solving the Problems] The method for manufacturing an aluminum heat exchanger of the present invention is similar to the above-described conventional method for manufacturing an aluminum heat exchanger, for example, as shown in FIGS.
After inserting the ends of the heat exchanger tubes 5, 5 made of aluminum alloy into the inside of each of the plurality of through holes 7, 7 formed in the tank 4 (2) made of aluminum alloy, the ends of the heat exchanger tubes 5, 5 are inserted. The outer peripheral surface and the inner peripheral edge of the through holes 7, 7 are liquid-tightly brazed.

Furthermore, in the method for manufacturing an aluminum heat exchanger of the present invention, before inserting the ends of the heat transfer tubes 5, 5 into the respective through holes 7, 7, the inner peripheral edges of each through hole 7, 7 are removed. and each heat exchanger tube 5, 5
It is characterized by coating polybutene on at least one of the outer peripheral surface of the end portion.

[0017]

[Function] In the case of the method for manufacturing an aluminum heat exchanger constructed as described above, due to the presence of polybutene having viscosity and lubricity, the ends of each heat exchanger tube 5, 5 are placed inside each through hole 7, 7. The work of inserting can be done smoothly.

It is a copolymer mainly composed of isobutylene, has one double bond at the end, and has the structural formula

The polybutene represented by [Chemical formula 1]
Since it depolymerizes and sublimates at temperatures below 400 to 450°C, the brazing material interposed between the outer peripheral surface of the end of each heat transfer tube 5, 5 and the inner peripheral edge of each through hole 7, 7 melts. , disappears without leaving any residue before brazing.

For this reason, each heat transfer tube 5 is placed inside each through hole 7, 7.
, 5 to smoothly insert the ends of the heat exchanger tubes 5, 5, the brazing between the heat exchanger tubes 5, 5 and the through holes 7, 7 will not be defective.

[0020] Polybutene has a molecular weight of 200 to 25
00 can be used, but the relationship with viscosity (
The higher the molecular weight, the higher the molecular weight), and those with a molecular weight of about 1,000 (viscosity of about 10,000 cSt) can be preferably used.

[0021] Furthermore, since polybutene can also be used as a dispersion medium for flux for brazing, it is applied to at least one of the inner peripheral edge of each through hole 7, 7 and the outer peripheral surface of the end of each heat transfer tube 5, 5. It is free to mix flux into the polybutene.

[0022]

[Effects of the Invention] Since the method for manufacturing an aluminum heat exchanger of the present invention is configured and operates as described above, the aluminum heat exchanger can be manufactured efficiently and the yield can be improved. .

[Brief explanation of the drawing]

[Figure 1] One of the conventionally known aluminum heat exchangers
FIG. 3 is a front view showing an example.

FIG. 2 is an exploded perspective view of essential parts.

FIG. 3 is a cross-sectional view of the main part.

FIG. 4 is a sectional view of main parts showing another example of a conventional heat exchanger.

[Explanation of sign]

1 Inlet pipe 2 Inlet side tank 3 Outlet pipe 4 Outlet side tank 5 Heat exchanger tube 6 Fin 7 Through hole 8 Seat board 9 Packing

Claims (1)

[Claims] Claim 1: After inserting the end of an aluminum alloy heat exchanger tube inside each of a plurality of through holes formed in an aluminum alloy tank, the outer circumferential surface of the end of the heat exchanger tube and the through hole are In the manufacturing method of aluminum heat exchangers in which the inner circumferential edge is liquid-tightly brazed, the inner circumferential edge of the through hole and the outer circumferential surface of the heat exchanger tube end are bonded together before the heat exchanger tube end is inserted into the through hole. A method for manufacturing an aluminum heat exchanger, characterized in that at least one side of the aluminum heat exchanger is coated with polybutene.