JP3126509B2 - Manufacturing method of aluminum heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an automotive heat exchanger such as an evaporator or a condenser, and more particularly to an improvement in a flat tube brazing method for an aluminum heat exchanger.

[0002]

2. Description of the Related Art Aluminum heat exchangers for automobiles include an evaporator, a condenser and a radiator, which are generally manufactured by a brazing method. In this manufacturing method, after assembling the various components of the heat exchanger, the components are put into a furnace and heated to integrally braze with a brazing material provided in advance. Various components of such an aluminum heat exchanger are mainly made of an aluminum alloy obtained by mixing metals such as manganese and the like with pure aluminum (hereinafter referred to as a core material). A material obtained by mixing a metal such as silicon with aluminum on the surface of a core material at a joint portion and cladding a brazing material of an aluminum-silicon alloy having a lower melting point than the core material of the aluminum alloy is used. Instead of assembling or cladding the brazing material, the components are assembled by placing the brazing material foil on the joint between the aluminum manganese alloy core component and the component.
Then, flux is applied to the brazing joint and brazed in a predetermined furnace, or brazing is performed in a vacuum furnace without applying the flux.

[0003] Among such aluminum heat exchangers, there is a type known as a multi-flow type as shown in FIG. 207,572). The multi-flow type heat exchanger 100 has a core 104 formed by interposing corrugated fins 103, which are heat transfer fins, formed between a plurality of flat tubes 102 through which a heat exchange fluid flows. The core 104 is provided between a pair of aluminum header tanks 101, 101 opposed to each other at a predetermined distance, and the flat tube 102 and the header tanks 101, 101 are assembled so as to communicate with each other. It is brazed integrally within. Note that reference numeral “105” in FIG. 5 is a reinforcing plate.

Since such a multi-flow type heat exchanger 100 is formed by brazing in a furnace, as shown in FIG. 6, the header tank 101 has a brazing material on the outer periphery of an aluminum alloy core material 101a. An open-ended cylindrical tube made of aluminum material clad with 101b is used, and a brazing material (not shown) is provided on the inner surface at the upper and lower ends of the cylindrical tube to join and close the openings at each end. A blind lid 106 made of an aluminum alloy is provided.
In addition, a number of flat tube insertion holes 107 are formed in the cylindrical tube, and the end of the flat tube 102 is inserted into each of the insertion holes 107. Corrugated fins 103 made of an aluminum alloy and having no brazing material clad on the surface are interposed between the flat tubes 102. Further, a hole for mounting an inlet pipe or a hole for mounting an outlet pipe (both not shown) is opened in the cylindrical pipe, and a brazing material (not shown) is clad outside each of these holes. Inlet tube 108 and outlet tube 1 made of aluminum alloy
09 is attached. In addition, the brazing material is clad on the core-side surface of the reinforcing plate 105.

As shown in FIG. 7, which is a cross-sectional view taken at right angles to the axis of the flat tube 102, the flat tube 102 has a core material 102a made of an aluminum alloy and a brazing material 102b clad on the outer periphery thereof. Inside the pipe 102, a flow path R
Are divided into a plurality, and an inner fin 110 for forming the small channel r is inserted. This inner fin 11
0 is intended to improve the heat transfer from the heat exchange fluid to the flat tube 102 and to improve the pressure resistance of the flat tube 102. The inner fin 110 is made of a thin aluminum alloy core material 110.
The material in which the brazing materials 110b and 110b are clad on both surfaces of the substrate a is used.

Meanwhile, in manufacturing the flat tube 102, conventionally, a band plate is bent by a forming roller, butt seam welding is performed in a state where both ends of the band plate are butted, and then cut to a predetermined length. It is known to form by doing. That is, FIG.
As shown in (1), a flat and long strip is bent into a U-shape with a center axis as a boundary by a plurality of forming rollers, and pipes are gradually formed until both ends are brought into a butt state. Then, while pressing the flat tubular side and bottom with squeeze rolls 111, 112, and 113, the roller electrode 115 to which the rotary welding transformer 114 is connected is pressed against the abutting portions of both ends 102c and 102d. The contact portion is welded in an argon gas atmosphere by applying a current to the flat tube 102 to form a flat tube 102.

When assembling a heat exchanger, a flat tube 102 in which inner fins 110 coated with a non-corrosive flux are inserted and corrugated fins 103 are alternately stacked to form a core 104. The end of the flat tube 104 is inserted into the flat tube insertion hole 107 of the header tank 101, reinforcing plates 105 are provided above and below the core 104, temporarily assembled, fixed with a jig, and fixed by a predetermined method. A non-corrosive flux is applied to the brazing portion, and the flat tube 102 and the inner fins 110,
The flat tube 102 and the corrugated fin 103, the flat tube insertion hole 107 of the header tank 101, the flat tube 102, and the like are brazed.

Here, the flat tube 102 in the core 104
The pitch between the corrugated fins 103 and the flat tube 1
02 are alternately combined and determined by compression, so that the variation in the pitch of the flat tubes 102 increases. In such a case, if the clearance between the flat tube insertion hole 107 of the header tank 101 and the flat tube 102 is small, the flat tube 102 may not be able to be inserted. Is being improved. However, the flat tube insertion hole 107 and the flat tube 1
If the clearance between the flat tube 102 and the flat tube 102 is large, the brazing material 102b on the outer periphery of the flat tube 102 may be insufficient, and the flat tube insertion hole 107 and the flat tube 102 may not be sufficiently brazed. Since liquid leakage may occur, the header tanks 101 and 101 are also clad or placed with a brazing material.

[0009]

However, in the above-described method for manufacturing the flat tube 102, butt seam welding is used, so that welding is indispensable, and expensive welding equipment is also required. Not only decreased, but also disadvantageous in terms of cost.

[0010] Therefore, the applicant has disclosed in Japanese Patent Application Laid-Open
A flat tube 116 as shown in FIG.
We tried to braze in a state of surface contact. That is, as shown in FIG. 9, a flat tube 116 having a flange-shaped protruding edge portion 116d protruding from a side edge portion was used. This flat tube 116 has a brazing material 116b on the outer surface of a core material 116a.
The flat plate 116, the corrugated fin 103, and the flat tube 1 are formed by the brazing material 116b.
16 and the header tank 101 are brazed or the flat tube insertion hole 107 is closed. A brazing material 116c is also clad on the inner surface of the core material 116a,
The flattened pipe 116 and the inner fin 117 are brazed between the mating surfaces 116e of d. The flat tube 116
Insert the inner fins 117, as shown in FIG. 9, initially, a slightly higher dimension h ₂ than the height h ₁ of the inner fin 117, the flange portion 116d is set to a state where a gap S in. And the inner fin 117
After applying a non-corrosive flux to the flat tube 1
16, the flat tube 116 is slightly crushed, and the flat tube 116 is set to a dimension H having a predetermined thickness. Then, it is fixed by using an assembling jig in the same manner as described above, the known non-corrosive flux is applied to the brazing portion, and the brazing portion is heated in a furnace. Between the surfaces 116e, 116e, between the flat tube 116 and the corrugated fin 103, the inner surface of the flat tube 116 and the inner fin 117, and furthermore, the flat tube 116 and the header tank 1
An attempt was made to braze 01 with a single brazing.

However, it has been found that when brazing in a furnace in this state, a minute hole may be formed near the fitting portion of the flat tube 116 to the header tank. This is because, in order to improve the heat exchange performance of the heat exchanger, the corrugated fins 103 and the flat tubes 116 are made thinner than the header tank 101 in thickness. It is considered that the flat tube 116 is caused by the temperature rising faster than the header tank 101. That is, since the corrugated fins 103 and the flat tubes 116 rise in temperature faster than the header tank 101, the brazing materials 116b and 116c of the flat tubes 116 melt first, and then the brazing material 101b of the header tank 101 melts. At this time, the brazing material 101b of the header tank 101 is called in because there is a gap in the flat tube insertion hole 107.
The brazing material 101b of the header tank 101 also comes into contact with the end of the mating surface 116e of the flat tube 11 by capillary action.
6 will be called into the mating surface 116e in large quantities.
As a result, the brazing silicon originally in the mating surface 116e of the flat tube 116 and the brazing silicon in the header tank 101 further diffuse into the mating surface 116e of the flat tube 116, resulting in an aluminum-silicon alloy with excessive silicon,
It is considered that the melting temperature of the core material 116a decreases, so that the so-called "brazing phenomenon by the brazing material" which erodes the core material 116a of the flat tube 116 occurs, and fine holes are generated. In particular, it is difficult to visually confirm the holes caused by such a pitting phenomenon, and it is difficult to determine whether or not such holes are formed by inspecting the heat exchanger after completion of the heat exchanger manufacturing process. The process cannot be found, and the yield of products may be reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a method of manufacturing an aluminum heat exchanger having low manufacturing cost, easy brazing work, and excellent adhesive strength. The purpose is to provide.

[0013]

In order to achieve the above object, the present invention provides a plurality of thin flat tubes in which a heat exchange fluid flows are provided in parallel with each other, and an aluminum pipe is provided between the flat tubes. A core formed by interposing the heat transfer fins is provided between thick aluminum header tanks opposed to each other at a predetermined distance and assembled so as to communicate the flat tube and the header tank, In the method for manufacturing an aluminum heat exchanger in which brazing is integrally performed in a furnace, the flat tube is formed by forming a strip having a brazing material on one surface and no brazing material on the other surface in an axial direction. Both ends are open and the surface on which the brazing material is not provided is on the inside, a flow path through which the heat exchange fluid flows is formed inside, and a protruding edge is formed on one or both side ends. In the flow path Bending along the line, forming the core using the flat tube, inserting the core into the brazing furnace with the header tank attached thereto, and connecting the both ends of the flat tube to the aluminum A method of manufacturing an aluminum heat exchanger, wherein a part of a brazing material provided in a header tank is used to braze the mating surfaces of the protruding edges.

[0014]

According to the present invention constructed as described above, a flat tube whose inner surface is not clad with a brazing material is inserted into the flat tube insertion hole of the header tank where the brazing material is clad, and a non-corrosive After the flux is applied, it is placed in a furnace and heated to a predetermined temperature, and the brazing material provided in the header tank melts out and is drawn into the end of the mating surface of the flat tube protruding portion by capillary action, and the flat tube protruding edge is formed. The brazing spreads over the entire joining portion of the portions, so that the occurrence of a so-called "erosion phenomenon by the brazing material" can be prevented, and the generation of fine holes can be prevented.

[0015]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing the relationship between a flat tube and a header tank according to one embodiment of the present invention, and corresponds to FIG. 6, in which inner fins are omitted, and FIG. FIG. 3 is a cross-sectional view of the flat tube before insertion of the fins, FIG. 3 is a cross-sectional view along line 3-3 in FIG. 1, and FIG. 4 is a cross-sectional view of another embodiment of the flat tube.

The header tanks 1 and 1 in the multi-flow type automotive condenser according to the present embodiment are cylindrical tubes having flat tube insertion holes 3 into which both ends of the flat tube 2 are inserted on the inner surface side. Although both ends are closed by a lid (not shown), the header tanks 1 and 1 are a core material 1a (JIS3003) of an aluminum alloy,
8% of the thickness of the brazing material 1b (JI
S4343) The thickness of the clad brazing material is 1.5 mm.
It consists of a plate material.

Next, the flat tube 2 has a core material made of an aluminum alloy material (JIS 3003) 2a, and has a brazing material 2b (JIS4) having a thickness of 8% only on the outer peripheral surface of the core material 2a.
343) is clad, and a strip having an overall thickness of 0.32 mm is used.

Here, the clad brazing material 2b is for brazing the flat tube 2 and the corrugated fins 4 and the flat tube 2 and the flat tube insertion holes 3 of the header tanks 1 and 1, respectively.

This strip is roll formed, and FIG.
Is formed in the flat tube 2 having the protruding edge portion 5 on one side edge as shown in FIG. 5, and the portion of the flat tube 2 into which the inner fin 6 is inserted is slightly higher than the height h of the inner fin 6. It has a dimension H, and a gap S is formed between the protruding edges 5. Then, the header tanks 1 and 1 are cut to a predetermined length according to the separation length.

The inner fin 6 is made of an aluminum alloy (JIS) serving as a core material 6a for brazing to the flat tube 2.
3003) Brazing material 6b of 13% of the plate thickness on both sides
(JIS 4343) clad plate thickness 0.32mm
In this case, a band plate having a degree is formed in a wave shape, and the waveform is shifted in a direction perpendicular to the axis by a predetermined length in the axial direction of the flat tube 2. By doing so, the heat exchange fluid flowing inside flows zigzag while colliding with the inner fins 6, thereby improving the heat exchange efficiency.

Further, as described above, the reason why the brazing material of the inner fin 6 is larger than that of the flat tube 2 is to prevent the brazing with the inner surface of the flat tube 2 from being insufficient and to reduce the pressure resistance. is there.

The corrugated fin 4 is made of a 0.32 mm thick aluminum material (J
IS3003) in the form of a wave.

To form the heat exchanger, first, the flat tube 2 having the inner fin 6 coated with the non-corrosive flux is crushed to a predetermined thickness.
And the corrugated fins 4 are alternately stacked to form a core 8, which is attached to the header tank 1, 1. Then, an aluminum reinforcing plate (not shown) in which a brazing material (JIS 4343) is clad on the core 8 side is attached to the outer surface of the outermost corrugated fin 4 and fixed by a printing jig. Thereafter, a non-corrosive flux is applied to the brazing portion by a known method so that the core 8 is horizontal, that is, the header tanks 1 and 1 are laid down, and the flat tubes 2 are
Is placed vertically in a furnace, brazing is performed, and the mating surface 5a of the protruding edge portion 5 of the flat tube 2 and the flat tube 2
An aluminum heat exchanger brazed between the inner fin 6 and the like is completed.

The state in which the core 8 is put into the furnace may be a state in which the protruding edge portion 5 of the flat tube 2 is located above or below.

Here, even if the brazing material is not provided on the inner surface of the flat tube 2, the heat exchanger in which the brazing material sufficiently penetrates the protruding edge 5 of the flat tube 2 is as follows. This is probably due to the reason.

When the core 8 of the heat exchanger is heated in the furnace,
Since the inner fins 6 and the flat tubes 2 are structurally thin, the temperature rise is faster than that of the thick header tanks 1 and 1, and the brazing material 1b of the header tanks 1 and 1 is used to solder the flat tubes 2 and the like. Material 2b is melted first and brazing material 1 in header tanks 1 and 1
b melts later. The brazing filler metal 1 of this header tank 1, 1
When b melts, the brazing filler metal 1b of the header tanks 1 and 1 is drawn into the gap between the flat tube insertion hole 3 and the flat tube 2 by capillary action, and is inserted into the mating surface 5a of the protruding edge 5 of the flat tube 2. The brazing filler metal 1b wraps around. Here, the mating surface 5 of the protruding edge 5
In the case a, the plate material itself is rolled by a roll, the surface is rough, and the flat tube 2 is roll-formed, so that there is a minute gap. It is considered that the brazing material 1b enters the entire mating surface 5a by capillary action and is brazed using the minute gap. Moreover, the brazing filler metal 1b of the header tanks 1 and 1
Since the brazing material 2b on the outer peripheral surface of the flat tube 2 and the flat tube 2 are also in contact with each other, there is a possibility that the brazing material 2b of the flat tube 2 may also enter the minute gap in the mating surface 5a of the protruding edge portion 5.

The present inventor conducted an experiment for assembling the components of the heat exchanger, forming the core 8 without providing the inner fin 6, and examining the flow state of the brazing material. The size of the flat tube 2 of this experimental example is 7 in the axial direction.
00 mm, width in the direction perpendicular to the axis is 17 mm, width of the protruding edge 5 is about 1
mm, and the outer diameter of the header tank 1, 1 is 22 mm.
I tried something about mm.

Further, as shown in FIG. 4, an experiment was carried out using a flat tube 2 having protruding edges 5 provided on both side edges of the flat tube. Regarding the size of the flat tube 2, the axial length is 700 mm, the width in the direction perpendicular to the axis is 17 mm, and the width of both protruding edges 5 is about 1 mm.
In FIG. 4, the same members as those shown in FIG. 2 are denoted by the same reference numerals.

In each of the experiments on the flat tubes 2, it was confirmed that the brazing material sufficiently entered the mating surfaces 5 a of the protruding edges 5 of the flat tubes 2. Considering that the inner fin 6 and the protruding edge 5 of the flat tube 2 are relatively far from each other and do not contact each other, the above result clearly indicates that the brazing material 6b clad on the inner fin 6 is flat. It is considered that the pipe 2 does not enter between the mating surfaces 5a of the protruding edge portion 5.

In particular, in this embodiment, since the brazing material is not clad on the mating surface 5a of the protruding edge portion 5 of the flat tube 2, even if the brazing material 1b of the header pipes 1 and 1 enters, the brazing material is not removed. Even if the amount of silicon does not increase and so does the diffusion of silicon to form a low-temperature portion in the core material 2a, so-called "eating" does not occur so that a hole is opened, so that it has sufficient strength to withstand use. In addition, a heat exchanger having the flat tube 2 having high reliability without leakage can be obtained.

It should be noted that the method of the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

For example, the brazing filler metal 1b may be clad on the inner surface of the header pipes 1, 1 or the brazing filler metal 1b may be put on the outer peripheral surface of the header pipes 1, 1 without cladding. The above-described embodiment is an example in which the present invention is applied to brazing of a flat tube in a multi-flow type condenser having header tanks 1 and 1 having a circular section perpendicular to the axis.
In addition to this header tank, an insertion hole for inserting a flat tube in a heat exchanger such as a condenser in which the header tank is formed by a separate member called a tank and a plate, a radiator for an automobile, and a hither core of an air conditioner for an automobile. Can be applied by cladding or laying a brazing material on a plate having

[0034]

As described above, according to the present invention, a flat tube having a protruding edge portion without a brazing filler metal on a flow passage surface through which a heat exchange fluid flows is used as a header having a brazing filler metal clad. After inserting the core into the flat tube insertion hole of the tank to form a core, applying a non-corrosive flux to it, and then placing it in a furnace and heating it to a predetermined temperature, the mating surface of the protruding edge of the flat tube is The brazing material in the header tank enters due to the capillary phenomenon, and the molten brazing material enters along the axial direction of the flat tube. Not only is it supplied in an appropriate amount, it is possible to achieve not only an excellent bonding strength and a joint free from erosion, but also extremely easy brazing operation and cost reduction.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a relationship between a flat tube and a header tank according to one embodiment of the present invention;

FIG. 2 is a cross-sectional view of a flat tube before inner fin insertion,

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1;

FIG. 4 is a cross-sectional view showing another embodiment of the flat tube;

FIG. 5 is a partially cutaway perspective view of a multi-flow type heat exchanger;

6 is a sectional view taken along line 6-6 in FIG. 5,

FIG. 7 is a cross-sectional view perpendicular to the axis of a conventional flat tube,

FIG. 8 is a schematic sectional view showing a state of manufacturing the flat tube,

9 is a sectional view showing a state before the flat tube shown in FIG. 10 is assembled;

FIG. 10 is a sectional view perpendicular to the axis of another conventional flat tube.

[Explanation of symbols]

1, 1 ... header tank, 1b ... brazing material, 2 ... flat tube, 2
a: brazing material, 4: heat transfer fin, 5: protruding edge, 5a: mating surface, 8: core, R: flow path.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Makoto Negishi 5-24-15 Minamidai, Nakano-ku, Tokyo Inside Calsonic Corporation (56) References JP-A-61-66091 (JP, A) JP-A-3 −155422 (JP, A) Actually open 63-109872 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 1/00 330 F28F 1/02

Claims (1)

(57) [Claims] 1. A plurality of thin flat tubes (2) through which a heat exchange fluid flows are provided in parallel with each other, and a heat transfer fin (4) made of aluminum is interposed between the flat tubes. The core (8) formed by the above is provided between thick aluminum header tanks (1, 1) opposed to each other at a predetermined distance, and the flat tube (2) and the header tank (1, 1) are connected to each other. In the method for manufacturing an aluminum heat exchanger which is assembled so as to communicate with each other and brazed integrally in a furnace, the flat tube (2) is provided with a brazing material (2a) on one surface and on the other surface A band plate in which the brazing material is not provided is formed such that both ends in the axial direction are opened and the surface on which the brazing material (2a) is not provided is an inner side, and a flow path (R) through which the heat exchange fluid flows is formed. Formed along the axis of the flow path (R) so that a protruding edge (5) is formed at one or both side ends. Bending molding, to form the core (8) with the flat tubes (2),
With the header tank (1, 1) attached to the core (8), the header tank (1, 1) was inserted into a brazing furnace, and was provided in the aluminum header tank (1) to which both ends of the flat tube (2) were joined. A method for manufacturing an aluminum heat exchanger, characterized in that a part of a material (1b) is brazed between mating surfaces (5a) of the protruding edges (5).