JPH05185205A - Brazing method for laminated heat exchanger - Google Patents

Abstract

PURPOSE:To inexpensively produce the laminated heat exchanger having excellent heat radiation performance without splashing flux residues to the surroundings after completion. CONSTITUTION:The content of Mg included in core materials and brazing filler metals which are respectively aluminum alloys is specified to <0.03wt.% and is confined as small as possible. A flux of a fluorine system, prior to the heating in the furnace, is stuck at 0.5 to 5g/m<2> ratio only on the surfaces in contact with each other of respective plate materials 2, 2 on one side of the plate materials 2, 2 constituting respective elements 6. The flux is not applied on the surfaces in contact with fins on the other side of the plate materials 2, 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION A brazing method for a laminated heat exchanger according to the present invention is incorporated in an automobile air conditioner,
It is used, for example, when manufacturing an evaporator to cool the air for air conditioning inside the vehicle.

[0002]

2. Description of the Related Art An air conditioner incorporates an evaporator that evaporates a refrigerant inside and cools air flowing outside. Built in an air conditioner like this,
As a heat exchanger used as an evaporator, a conventional heat exchanger is disclosed in, for example, JP-A-61-49995.
The laminated evaporators as shown in FIGS.

Each of the laminated evaporators is made of aluminum or an aluminum alloy (these are collectively referred to as "aluminum material" in the present specification), and has a pair of protrusions spaced from each other on one edge. Parts 1a, 1
An inverted U-shaped concave portion 3 is formed on one surface of the plate member 2 on which the b is formed, with both ends of the concave portion 3 continuing to the edges of the pair of protrusions 1a and 1b. A large number of projections 4 and 4 are formed inside the concave portion 3 to disturb the flow of the refrigerant flowing inside the folded flow path formed by the concave portion 3 so that the heat exchange between the refrigerant and the plate member 2 is efficient. Try to be well done.

In the case of a laminated evaporator manufactured by using such a plate material 2, the plate materials 2 and 2 are made into a set of two, and the recesses 3 and 3 of the plate materials 2 are stacked in the middle in a state of facing each other. The elements 6 and 6 each having an inverted U-shaped folded back flow path and a pair of bonding portions 5a and 5b located at both ends of the flow path and projecting from the edge portions by joining together in a liquid-tight manner And

Then, the joint portions 5a and 5b of the plurality of elements 6 and 6 are inserted into the slit-shaped connection holes 9 and 9 formed on the upper surfaces of the first and second tanks 7 and 8, respectively. , The outer peripheral surface of each joint 5a, 5b and each connection hole 9,
The inner peripheral edge of 9 is brazed and joined liquid-tightly. Each of the tanks 7 and 8 is constructed by combining a seat plate 10 and a tank body 11 as shown in FIG. 2 and brazing liquid-tightly to each other. Is formed in. Further, fins 12 and 12 are provided between the adjacent elements 6 and 6.

The inside of the first tank 7 is divided into an inlet chamber 14 and an outlet chamber 15 by being partitioned by a partition wall 13 fixed to an intermediate portion, and a refrigerant feed port 16 is provided on the inlet chamber 14 side.
A refrigerant outlet 17 is provided on the side of the outlet chamber 15, and the refrigerant sent from the refrigerant inlet 16 flows through the return flow path in each element 6, 6 and is taken out from the refrigerant outlet 17. I try to evaporate during.

By the way, in the case of manufacturing a laminated evaporator having the above-mentioned structure and functioning, the plurality of elements 6,
6, the fins 12, 12, the first and second tanks 7, 8 and the partition wall 13 are combined in the state shown in FIG. 1 and temporarily fixed by a jig (not shown), and the above-mentioned members 6, 12, 7, 8
Is heated in a heating furnace.

A plate member 2 constituting the plurality of elements 6 and 6,
No. 2 is made of a so-called clad material in which a clad layer which is also a brazing material made of an aluminum material is formed on both surfaces of a core material made of an aluminum material. When melted and cooled and solidified again, the plate materials 2 and 2 composing the plurality of elements 6 and 6, as well as the elements 6 and 6 and the fins 12 and 12 and the first and second tanks 7 and 8, respectively. , The first and second tanks 7,
The seat plate 10 and the tank main body 11, which form part 8, and the first tank 7 and the partition wall 13 are brazed.

[0009]

However, when brazing of a laminated heat exchanger such as a laminated evaporator is carried out as described above, flux residue is left on the surface of the laminated heat exchanger after brazing. A relatively large amount adheres, and the residue deteriorates the appearance of the completed laminated heat exchanger. In addition, the residue (white powder) separated from the laminated heat exchanger incorporated in the automobile air conditioner may be ejected from the outlet of the air conditioner into the automobile compartment, causing discomfort to passengers.

As a technique for preventing such a residue from adhering to the outer surface, Japanese Unexamined Patent Publication (Kokai) No. 64-44267 discloses a plate material 2 which constitutes a plurality of elements 6, 6 with one surface of each of the plate materials 2. There is described a technique in which the flux is applied only to the surface where the two come into contact with each other, and the flux is not applied to the surface that contacts the fins 12 and 12 on the other surface of the plate materials 2 and 2.

However, in the case of the prior art described in the above publication, the clad layer formed on the surface of each plate 2, 2 is contained in an amount of 0.1 to 0.5% by weight (hereinafter, when a mixing ratio is expressed. , Which is simply “%”.) Since the brazing material contains Mg, the brazing material between the plate materials 2 and 2 and the fins 12 and 12 can be achieved even if the plate materials 2 and 2 are brazed well. It was difficult to make sure.

That is, various fluxes have been conventionally known as the fluxes used for brazing aluminum materials, but the brazing property is good, and the residue generated after brazing is against the aluminum materials. As a flux having no corrosive property, for example, Japanese Patent Publication No. 58-2703.
Fluorine-based flux as described in Japanese Patent No. 7 can be preferably used.

On the other hand, as in the technique described in Japanese Patent Laid-Open No. 64-44267, the flux is applied only to the contact surfaces of the plate members 2 and 2 and the flux is applied to the surfaces contacting the fins 12 and 12. In the case of the technology that does not apply
The brazing between the fins 12 and the fins 12 must be performed by the flux vapor floating in the heating furnace, which is generated when the flux existing on the contact surface evaporates.

However, when Mg is contained in the brazing material, F in the above flux and this Mg combine to form KMGF.
_{Since 3} or MgF ₂ compound is generated, the amount of flux consumed at the abutting surface portion is increased, and the amount of flux vapor floating in the heating furnace is reduced.
The brazability between the fins 12 and 12 becomes poor.

Of course, even if a flux other than a fluorine-based flux is used, or if a fluorine-based flux is used, the above problem can be solved by increasing the amount used. However, when a flux other than a fluorine-based flux is used, a cleaning operation for washing out the corrosive residue after brazing is required, which increases the manufacturing cost of the laminated heat exchanger.
Further, when the amount of the fluorine-based flux used is increased, not only the manufacturing cost increases due to the increase in the amount of the expensive fluorine-based flux used, but also the elements 6, 6 formed by combining the plate materials 2 and 2 are used. A large amount of residue is generated, and this residue becomes a resistance against heat exchange between the refrigerant flowing in each element 6 and 6 (although it does not scatter in the automobile interior) and the aluminum material forming each element 6 and 6. However, it is also not preferable because it causes deterioration of performance of the laminated heat exchanger after completion.

The brazing method for a laminated heat exchanger of the present invention eliminates the above-mentioned disadvantages.

[0017]

A brazing method for a laminated heat exchanger according to the present invention is similar to the conventional brazing method for a laminated heat exchanger described above, in which a brazing material clad layer is provided on both surfaces of a core material. Made of an aluminum material, and two plate materials each having a recess formed on one surface thereof are stacked in the middle with the recesses facing each other to form an element having a flat flow path inside, After stacking a plurality of elements with fins provided between adjacent elements, the plurality of elements and the fins are heated in a heating furnace to melt the brazing filler metal to form the plurality of elements. The plate materials are brazed together, and the elements and the fins are brazed.

Particularly, in the brazing method for the laminated heat exchanger of the present invention, the amount of Mg contained in the core material and the brazing material is made as small as possible to be less than 0.03% by weight. With
Prior to heating in a heating furnace, a fluorine-based flux is adhered at a rate of 0.5 to 5 g / m ² only on one surface of the plate material constituting each element and the surface where the plate materials contact each other. The other surface of the plate material, which is in contact with the fins, is not coated with flux.

[0019]

In the brazing method of the laminated heat exchanger of the present invention configured as described above, the Mg contained in the core material and the brazing material is
Keep the amount of (amount as close to 0% by weight as possible)
Therefore, when the plate material coated with the fluorine-based flux is heated in the heating furnace in order to reduce the consumption of the fluorine-based flux, a relatively large amount of the fluorine-based flux vapor floats in the heating furnace.

Therefore, the brazing between the plate material and the fin, which is not directly coated with the fluorine-based flux between the contact surfaces,
Well done.

Further, since the amount of applied flux itself is suppressed to be small, a large amount of flux residue does not adhere to the inner surface of each element, and the performance of the laminated heat exchanger after completion is improved.

[0022]

EXAMPLES The following table shows the results of experiments conducted by the present inventors to confirm the effects of the present invention.

[Table 1] In the experiment, first, a plate material 2 as shown in FIG. 2 was made from aluminum materials having different amounts of Mg added, and the application method and the application amount of the fluorine-based flux on the plate material 2 were varied. By doing so, a laminated heat exchanger as shown in FIG. 1 was produced.

All the aluminum plates constituting the plate material 2 are JIS 3003 materials (Si of 0.6% or less, F of 0.7% or less).
e, 0.20 to 0.50% Cu, 1.0 to 1.5% M
n, 0.10% or less of Zn, 0.05% or less of each, and 0.15% or less of impurities as a whole, the remainder is aluminum alloy) based on both sides of the core material based on JIS 40
45 materials (9.0-11.0% or less Si, 0.8% or less F
e, Cu of 0.30% or less, Mn of 0.05% or less, 0.0
Mg less than 5%, Zn less than 0.10%, less than 0.20%
A brazing filler metal based on Ti, an aluminum alloy containing 0.05% or less of each and 0.15% or less of impurities as a whole, and the balance of Al, and clad (laminated) at a ratio of 10% each. It was used.

[+ Mg] representing the aluminum material component
The "numerical value" of "numerical value" represents the total amount of Mg contained in the aluminum material (originally JIS 3003 material or JIS
It is not added to the Mg contained in 4045 wood. ).

The fluorine-based flux is described in the above Japanese Patent Publication No. 27037/58, and is disclosed in "NOCOLOK FLU".
The one commercially available as "X" was used. Flux was applied only to Comparative Example 5 on both sides of the plate material 2,
In the other experimental examples (Invention Products 1 to 4 and Comparative Examples 1 to 4), the flux was applied only to the abutting surfaces of the plate materials 2 and the flux was applied to both surfaces of the plate material 2 only in Comparative Example 5 described above. ..

The flux application operation was performed by spraying 10% slurry onto the plate material 2. The heating brazing is performed in a nitrogen gas atmosphere with a dew point of −30 ° C., an oxygen concentration of several 10 p.pm or less, heating temperature × time = 600 ° C. × 3.
It was performed under the condition of min. However, the flux may be applied by another method such as electrostatic powder coating. The amount of flux applied in the above table is the weight in the dry state.

Compressed air is blown onto the outer surface of the thus obtained laminated heat exchanger, and the flux residue attached to the outer surface of the laminated heat exchanger is blown off and collected, and the weight of the collected flux residue is collected. Was measured to obtain the amount of residue scattering.

Further, the elements 6, 6 of the laminated heat exchanger after completion
By visually observing the bonding portion between the fins 12 and 12, the brazing properties of both members 6 and 12 were evaluated, and the fin adhesion ratio was described in the above table. The fin adhesion rate is
For the contact length L ₀ between each element 6, 6 and the fin 12, 12, each element 6, 6 and the fin 12, by heat brazing,
12 is the percentage of the length L ₁ of the fillet formed between 12 and 100 (100 L ₁ / L ₀ ).

Further, a vapor compression refrigerator was constructed by using the obtained laminated heat exchanger as an evaporator, and the heat radiation performance of this laminated heat exchanger was measured. The heat dissipation performance was expressed as a ratio to Comparative Example 4 with Comparative Example 4 as 100.

In the above table showing the experimental results, Comparative Example 1
Comparative Example 2 shows that since the amount of flux applied is small, the fin adhesion rate is low, and as a result (the heat transfer between the elements 6 and 6 and the fins 12 and 12 is poor), the heat dissipation performance is poor.
Is a case where the amount of Mg contained in the brazing filler metal is large, resulting in a low fin adhesion rate, resulting in poor heat dissipation performance. Comparative Example 3 has a large amount of Mg contained in the core member Low rate,
As a result, in the example in which the heat dissipation performance is poor, in Comparative example 4, the amount of the flux used is large and a residue is generated on the inner surfaces of the elements 2 and 2,
An example in which the heat dissipation performance is not necessarily good is Comparative Example 5 in which the plate material 2 is used.
Since the flux is applied to both sides of each of the above, the examples in which the amount of residue scattering is large are shown respectively.

Compared with the above Comparative Examples 1 to 5, the products of the present invention 1 to
In No. 4, all of the amount of residue scattering, the fin adhesion rate, and the heat dissipation performance are good.

[0032]

Since the brazing method for a laminated heat exchanger of the present invention is constructed and implemented as described above, it does not scatter the flux residue after completion and has excellent heat dissipation performance. The mold heat exchanger can be provided relatively inexpensively.

[Brief description of drawings]

FIG. 1 is a perspective view showing a laminated evaporator, which is an example of a laminated heat exchanger manufactured by a brazing method of the present invention.

FIG. 2 is a partially exploded perspective view of this evaporator.

[Explanation of sign]

 1a Projection part 1b Projection part 2 Plate material 3 Recess 4 Protrusion 5a Joining part 5b Joining part 6 Element 7 First tank 8 Second tank 9 Connection hole 10 Seat plate 11 Tank body 12 Fin 13 Partition wall 14 Inlet chamber 15 Outlet chamber 16 Refrigerant inlet 17 Refrigerant outlet

Claims (1)

[Claims] 1. A plate made of an aluminum material having a brazing material clad layer on both surfaces of a core material, and two plate materials each having a concave portion formed on one surface thereof are superposed in the middle with the concave portions facing each other. By combining them to form an element having a flat flow path inside, stacking multiple elements with fins between adjacent elements, heat the multiple elements and fins in a heating furnace. In the brazing method of the laminated heat exchanger, the brazing material is melted, the plate materials constituting the plurality of elements are brazed together, and the elements and the fins are brazed. The amount of Mg contained is 0.03
The content is made as small as possible by less than 10% by weight, and prior to the heating in the heating furnace, the fluorine-based flux is reduced to 0.
A brazing method for a laminated heat exchanger, which is characterized in that the flux is applied at a rate of 5 to 5 g / m ² and flux is not applied to the other surface of the plate material that comes into contact with the fins.