JPH11245023A - Manufacture of heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a deterioration of brazing property due to a shape holding member in a manufacturing method to form a spacing part by arranging the shape holding member of a given size in a core part, before a brazing is carried out. SOLUTION: Out of the shape holding member 11 which is made of a carbon and is not brazed, a face in contact with a flat tube 6 is made to be a concave- convex face having a convex face 11a and a concave face 11b extending in a direction to cross a longitudinal direction of the flat tube 6 so that the shape holding member 11 comes into contact with a flat tube 6 at a convex face 11a portion. By doing so, the shape holding member 11 does not get into full contact with the flat tube 6 and the concave face 11b becomes a permeation path of a flux, resulting in that the flux can be fully applied to a tube joining part 6c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger manufactured by brazing, in which a shape retaining member (jig) having a predetermined size is arranged in a core portion before brazing to form a space portion. The present invention relates to a forming method.

[0002]

2. Description of the Related Art The present inventors have proposed a heat exchanger for heating a vehicle using hot water (engine cooling water) heated by a vehicle engine (internal combustion engine) as a heat source. In order to eliminate the shortage of the heat source, an electric heating element is integrated in the heat exchanging core portion and air is heated by the electric heating element. A patent application proposes a "heat exchanger for heating in which an electric heating element is integrated".

In the prior application, as shown in FIGS. 8 to 10, a plurality of flat tubes 6 through which hot water flows are arranged in parallel, and a corrugated fin 7 is joined between the plurality of flat tubes 6. Heat exchange core 3
In the heating heat exchanger configured as described above, a predetermined interval space for installing the electric heating element unit 9 is set in a part of the heat exchange core unit 3 and the heat exchange core unit 3 is brazed. After assembling, the electric heating element unit 9 is installed in the above-mentioned part.

The electric heating element unit 9 comprises a heating element 9
0a, and the heating element main body 90 is attached to the frame 9 via corrugated fins 91 and 92.
3 and 94 are integrally held inside. According to this, the electric heating element unit 9 can be installed after the assembly of the heat exchange core 3 (after the completion of the integral brazing), so that the electrical characteristics of the heating element 90a can be obtained by brazing the heat exchange core 3. There is no danger of spoiling. In addition, the electric heating element unit 9 is previously provided inside the frames 93 and 94 with the heating element main body 9.
0 and the corrugated fins 91 and 92 are integrally formed as one unit, and the heat exchange core 3 is a corrugated fin type, so that a flat tube corresponding to the thickness of the electric heating unit 9 is formed. Only by removing the corrugated fin 6 and the corrugated fin 7, the electric heating element unit 9 can be easily assembled to the heat exchange core 3.

Meanwhile, as a manufacturing method for setting a space portion at a predetermined interval in a part of the heat exchange core portion 3 composed of a combination of the flat tube 6 and the corrugated fin 7, a conventional method has been known. According to this conventional method, as shown in FIG. 11, the shape retaining member 11 is disposed so as to be in close contact with the flat surfaces of the flat tubes 6 adjacent to each other, as shown in FIG. ing.

[0006]

Therefore, the shape retaining member 1
It has been found that the presence of 1 hinders the application of the flux to the flat tube 6 and deteriorates the brazing property of the flat tube joint 6c. That is,
When assembling each part of the heat exchanger by integral brazing, a flux is injected from the injector 12 to the heat exchanger assembly to secure brazing properties, and aluminum constituting each part of the heat exchanger is formed. Apply flux to the member surface. This flux removes the oxide film on the surface of the aluminum member of the heat exchanger and prevents the re-oxidation, thereby improving the brazing property of the aluminum member.

However, according to the above-described conventional method, since the shape retaining member 11 is completely adhered to the flat surface of the flat tube 6, the application of the flux to the tube flat surface in contact with the shape retaining member 11 is hindered. As a result, in FIG. 11, it has been found that poor brazing of the central joint 6c of the flat tube 6 occurs, which causes fluid leakage from the flat tube 6 (for example, leakage of warm water for heating).

[0008] The present invention has been made in view of the above points,
An object of the present invention is to provide a manufacturing method for forming a space by arranging a shape retaining member having a predetermined size in a core portion before brazing, thereby eliminating the deterioration of brazing property due to the shape retaining member.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, the surface of the shape-retaining member (11) which is in contact with the flat tube (6) is made to extend in the longitudinal direction of the flat tube (6). Convex surface (11) extending in a direction orthogonal to the
a) and an uneven surface having a concave surface (11b), wherein the shape retaining member (11) is in contact with the surface of the flat tube (6) at the convex surface (11a).

According to this, the shape retaining member (11) does not entirely contact the surface of the flat tube (6), and the concave portion (11b) of the shape retaining member (11) becomes a flux permeation path. Therefore, the flux can be sufficiently applied to the joint (6c) of the flat tube (6) through the concave surface (11b). As a result, even in a heat exchanger in which a space is formed by arranging a shape retaining member (11) having a predetermined size in the core (3) before brazing, the shape retaining member (11) is obstructed. Without being performed, the flux is sufficiently applied to the flat tube (6), so that the joint (6c) of the flat tube (6) can be satisfactorily brazed.

More specifically, the present invention relates to a heat exchanger in which an electric heating element unit (9) is assembled in a space formed after removing a shape retaining member (11). Can be implemented well. Further, when the convex surface (11a) and the concave surface (11b) are inclined at a predetermined angle (θ) with respect to a direction orthogonal to the longitudinal direction of the flat tube (6), the flat tube ( 6) In the longitudinal direction, adjacent convex surfaces (11a) overlap each other (1).
1c) can be formed, the thickness of the flat tube (6) can be well controlled, and the variation in the thickness of the flat tube (6) can be eliminated.

Further, according to the present invention, the groove (1) for dividing the convex surface (11a) in the middle of the convex surface (11a).
If 1e) is formed, the flux can be more appropriately applied to the flat tube (6) through the groove (11e). In addition, the code in parentheses of each of the above means,
It shows the correspondence with specific means described in the embodiment described later.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. (First Embodiment) First, the overall structure of a vehicle heat exchanger manufactured by the method of the present invention will be described with reference to FIGS. This heat exchanger has a hot water inlet side tank 1
And a hot water outlet side tank 2 and a heat exchange core 3 provided between the tanks 1 and 2.

The hot water inlet tank 1 is provided with an inlet pipe 4 into which hot water (engine cooling water) from a vehicle engine (not shown) flows, and the hot water outlet tank 2 allows hot water to flow outside and return to the engine side. An outlet pipe 5 is provided. Since the heat exchanger of this example is vertically symmetrical as shown in FIG. 8, the hot water inlet side tank 1 and the hot water outlet side tank 2 may be upside down.

Each of the tanks 1 and 2 has a tank body 1
a and 2a, and a sheet metal 1b and 2b for closing the opening end surfaces of the tank main bodies 1a and 2a, and has a well-known tank structure in which the left-right direction in FIG. A large number of flat tube insertion holes (not shown) are formed in the sheet metals 1b and 2b, and are arranged in one or more rows in the left-right direction of FIG.

The heat exchanging core 3 has a plurality of flat tubes 6 formed in a flat shape parallel to the flow direction of heating air (the direction of arrow A in FIG. 8) and arranged in parallel in the left-right direction in FIG. ing. A corrugated fin (fin member) formed in a wave shape between the plurality of flat tubes 6.
7 are arranged and joined. As is well known, a large number of louvers 7a (see FIG. 1 and the like) are cut and raised in the corrugated fin 7 at a predetermined angle with respect to the flow direction of the heating air, and fin heat transfer is performed by forming the louver 7a. The rate is improving.

Openings at both ends of the flat tube 6 are inserted into tube insertion holes of the sheet metals 1b and 2b, respectively.
Joined. Further, side plates 8a and 8b are disposed further outside the corrugated fins 7 on the outermost sides (the left and right ends in FIG. 8) of the core portion 3, and the side plates 8a and 8b are provided.
8b is joined to the outermost corrugated fin 7 and sheet metal 1b, 2b.

In the heat exchanger of the present embodiment, all of the components 1 to 8b are formed of aluminum (including an aluminum alloy), and the respective parts are integrally joined and assembled by brazing. Further, an electric heating element unit 9 is installed at a part of the heat exchange core unit 3, and more specifically, in the example of FIG.
The electric heating element units 9 are installed at equal intervals at the four locations. In order to install the electric heating element unit 9, one flat tube 6 is provided at a predetermined portion of the heat exchange core 3.
The corrugated fins 7 joined to both sides of the flat tube 6 are removed to form a space portion with a predetermined interval set, and in this state, after the heat exchanger is brazed, the heat exchange core portion is formed. An electric heating element unit 9 is inserted into the flat tube 6 and the corrugated fin 7 in the portion 3.

Therefore, the thickness t ₀ of the electric heating element unit 9
(FIG. 9) is set equal to the thickness of the single flat tube 6 and the corrugated fins 7 on both sides thereof, and the length L is set equal to the dimension between the sheet metals 1b and 2b. . 9 and 10 illustrate a specific structure of the finned electric heating unit 9. The electric heating unit 9 is roughly divided into a heating element main body 90, corrugated fins (fin members) 91 and 92, It is composed of frames 93 and 94. First, the heating element main body 90 is shown in FIG.
0, a plate-like heating element 90a
, And a three-layer sandwich structure comprising elongated flat electrode plates 90b and 90c arranged on both front and back surfaces of the heating element 90a.

A covering member 90 made of an electrically insulating material is provided around the entire periphery of the electrode plates 90b and 90c.
d. Here, the heating element 90a is a PTC heater made of a resistor material (for example, barium titanate) having a positive resistance temperature characteristic whose resistance value increases rapidly at a predetermined set temperature T ₀ (for example, around 150 ° C.). Element. Both electrode plates 90b and 90c of the heating element 90a are formed from a conductive metal material such as aluminum, copper, and stainless steel. Heating element 90a and both electrode plates 90b, 90
By pressing each other c, electric conduction between them is obtained.

The heating element main body 90 is assembled in the two frames 93 and 94 such that the covering member 90d is pressed against the corrugated bent tops of the corrugated fins 91 and 92 on both sides. As a specific material of the covering member 90d, a resin having high heat resistance (for example, a polyimide resin or the like) is preferable.
The electrode plate 90b is a positive electrode plate, and the electrode plate 90c is a negative electrode plate. Terminal portions 90e and 90f for electrical connection to an external circuit are integrally formed. An external control circuit (not shown) is electrically connected to the terminal portions 90e and 90f, and power is supplied to each electric heating unit 9 from a vehicle-mounted power supply via the external control circuit.

Next, the corrugated fins 91 and 92 have the same corrugated shape as the corrugated fins 7 of the heat exchange core 3, and are made of a metal having excellent thermal conductivity such as aluminum. The frames 93 and 94 are formed in a U-shape from a metal having excellent thermal conductivity such as aluminum and stainless steel.
A plurality (two in this example) of mounting pieces 93a, 94a are formed on the frame bodies 93, 94 in the middle of both sides in the longitudinal direction (both sides before and after the air flow direction A).

The two frame members 9 are formed by overlapping the tips of the mounting pieces 93a and 94a with each other and joining the overlapped portions by means such as welding or brazing.
3 and 94 are joined together, and two frames 93,
94, the heating element body 90 and the corrugated fin 9
By applying a pressing force to the first and second frames 92 and 94,
The heating element main body 90 and the corrugated fin 9
1, 92 are held.

Reference numeral 10 denotes a fastening (band) member made of a metal material having excellent corrosion resistance such as stainless steel, and is disposed on both the air inlet side surface and the air outlet side surface of the heat exchange core 3. . The fastening member 10 has a hook portion having a bent shape at both ends thereof, and this hook portion is pulled into locking grooves 8c, 8d formed at the longitudinal center portions of the upper and lower side plates 8a, 8b. Hang it and attach it between the upper and lower side plates 8a, 8b.

By mounting the fastening member 10, a tightening force in the compression direction acts on the heat exchange core portion 3.
It is possible to obtain a tightening force for pressing and holding the electric heating unit 9 between the two adjacent flat tubes 6. In FIG. 8, the fastening members 10 are arranged at only one central position in the vertical direction of the heat exchange core 3, but the fastening members 10 may be arranged at a plurality of positions in the vertical direction.

Next, a method of manufacturing the above-described heating heat exchanger will be described. First, a core assembling step of assembling a heat exchanger configuration is performed. That is, as shown in FIG. 1, the flat tube 6 and the corrugated fin 7 of the heat exchange core 3
Are alternately stacked, and among the heat exchange core portions 3,
At the portion where the electric heating element unit 9 is installed (the four hatched portions in FIG. 8), in order to maintain a predetermined interval K between two adjacent flat tubes 6, 6, the two flat tubes 6 are used. Between 6 and 6, a shape retaining member (jig) 11 having the same width dimension as the predetermined interval K is inserted.

The shape-retaining member 11 is formed of a material (for example, carbon or the like) having a heat resistance to an integral brazing process described later and having a property of not being brazed with aluminum. As shown in FIG. 2, the surface of the shape retaining member 11 that is in contact with the flat surfaces of the flat tubes 6, 6 is
An uneven surface extending in a direction (in other words, the air flow direction A) orthogonal to the longitudinal direction of the flat tubes 6, 6 (vertical direction in FIG. 1) is formed. Therefore, in the shape retaining member 11, a large number of convex surfaces 11a that are in contact with the flat surfaces of the flat tubes 6, 6 and a large number of concave surfaces 11b that are not in contact with the flat surfaces of the flat tubes 6, 6 are alternately formed. Note that the longitudinal dimension of the shape retaining member 11 is slightly shorter than the longitudinal dimension of the flat tubes 6, 6 in order to facilitate the assembling work into the core portion 3.

In the above core assembling step, the tank 1,
As a matter of course, the entire configuration of the heat exchanger shown in FIG. 8 is also assembled by assembling the pipes 4, 5, and the side plates 8a and 8b. Next, as described above, the assembled state of the assembled heat exchanger assembly is held by an appropriate jig (not shown).

Next, a flux is sprayed from a flux injector (nozzle) 12 onto the outer surface of the heat exchanger assembly, and the flux is applied to the surface of each aluminum member of the heat exchanger assembly. Here, of the shape-retaining member 11, the surfaces of the flat tubes 6, 6 which are in contact with the flat surfaces of the flat tubes 6, 6
1 has an uneven surface extending in a direction perpendicular to the longitudinal direction (vertical direction in FIG. 1) (in other words, the air flow direction A).
Since the concave surface 11b of the shape retaining member 11 is parallel to the flux spraying direction from the flux injector 12, the flux passes through the concave surface 11b also in the flat tubes 6 on both the left and right sides of the shape retaining member 11, and the flux is formed. It can penetrate to the joint 6c located at the center of the flat surface of the flat tubes 6, 6, and a sufficient flux can be applied to the vicinity of the joint 6c.

Here, the specific configuration of the flat tube 6 will be described. The flat tube 6 is a thin plate-like material in which a brazing material (for example, A4000 series) is clad on both sides or one side of an aluminum core material (for example, A3000 series). Using an aluminum clad material, the aluminum clad material is wound and tightened as shown in FIG. 1 to form two flat hot water passages 6a and 6b independently, and the two flat hot water passages 6a and 6b. 6c in the middle of 6b
Has been arranged. This joint 6c is to be brazed at the same time as the integral brazing of the entire heat exchanger described later.

The corrugated fin 7 is made of an aluminum bare material having no brazing material clad (for example, A3000).
System). As the flux, a non-corrosive fluoride-based flux (such as KF / AlF ₃ ) is preferable. After the above flux application step is completed, the heat exchanger assembly is carried into a brazing furnace while being held by the jig, and the brazing step is performed. That is, the inside of the brazing furnace is maintained in a nitrogen gas or inert gas atmosphere, and in this atmosphere, the heat exchanger assembly is heated to a brazing temperature (6 ° C.).
(To about 00 ° C.) to melt the brazing material of the aluminum clad material of each member of the heat exchanger, and integrally braze the members of the heat exchanger assembly. The time of this brazing step is about several minutes.

In this brazing step, the shape retaining member 11
In the adjacent flat tubes 6, 6, the shape-retaining member 11 abuts against the flat surface, but as described above, sufficient flux is also provided near the joint 6 c of the flat tubes 6, 6 through the concave surface 11 b of the shape-retaining member 11. Is applied, so that the brazing property of the joint 6c of the flat tubes 6, 6 can be favorably maintained.

Further, the shape retaining member 11 and the flat tubes 6, 6
Are in contact only with the convex surface 11a, and the contact area between the two is reduced. Therefore, at the time of brazing, due to the shape retaining member 11 having a large heat capacity, the flat tubes 6,
The rate of temperature rise of the flat tubes 6 can be suppressed from being smaller than that of the flat tubes 6 at other portions, and this also contributes to securing the brazing property of the flat tubes 6 adjacent to both sides.

After the above brazing step is completed, the heat exchanger assembly is carried out of the brazing furnace, and after the temperature of the heat exchanger assembly has dropped to room temperature, the assembly process of the electric heating unit 9 is completed. I do. The electric heating unit 9 is independently assembled separately from the heat exchanger assembly to complete the structure shown in FIG. Then, the four shape retaining members 11 inserted between the two flat tubes 6 in the heat exchange core portion 3 of the heat exchanger assembly are taken out, and the two flat tubes 6 are removed. The electric heating element unit 9 is assembled in the space formed at a predetermined interval K so that the outer surfaces of the two frames 93 and 94 are in contact with the flat tube surface. After this assembling, the hook portions at both ends of the fastening member 10 are hooked on the locking grooves 8c, 8d of the upper and lower side plates 8a, 8b,
The fastening member 10 is mounted between the upper and lower side plates 8a and 8b so that the heat exchange core 3 is compressed.

Thus, a tightening force for pressing and holding the electric heating unit 9 between the two flat tubes 6, 6 is applied to the heat exchange core 3, and the electric heating unit 9 is connected to the two tubes. It can be securely held and fixed between the flat tubes 6. (Second Embodiment) FIG. 3 shows a shape retaining member 1 according to a second embodiment.
1, and the convex surface 11a and the concave surface 11b are inclined at a predetermined angle θ falling rightward. Due to this inclination angle θ, a wrap portion 1 is formed between the upper convex surface 11a and the lower convex surface 11a.
1c is formed.

According to the shape retaining member 11 of the first embodiment, a pressing surface by the convex surface 11a and a non-pressing surface by the concave surface 11b are alternately formed along the longitudinal direction of the flat tubes 6, 6, and the non-pressing surface by the concave surface 11b. The pressing force does not act on the flat surfaces of the flat tubes 6, 6 in the surface portion, and the flat tubes 6, 6
6 becomes difficult to control. On the other hand, according to the shape retaining member 11 of the second embodiment, due to the presence of the wrap portion 11c of the convex surface 11a, the pressing surface formed by the convex surface 11a is continuous along the longitudinal direction of the flat tubes 6, 6 without being interrupted. The thickness of the flat tubes 6, 6 can be controlled well, and variations in the thickness of the flat tubes 6, 6 can be eliminated.

(Third Embodiment) FIG. 4 shows a shape retaining member 11 according to a third embodiment, which has a shape having a hollow portion 11d at the center. Due to the formation of the hollow portion 11d, the mass of the whole shape retaining member 11 is reduced, and the shape retaining member 11 is accordingly reduced.
Heat capacity can be reduced. As a result, at the time of brazing, the rate of temperature rise of the shape retaining member 11 can be increased, so that a decrease in the rate of temperature rise of the adjacent flat tubes 6, 6 due to the presence of the shape retaining member 11 can be more favorably suppressed. it can.

(Fourth Embodiment) FIG. 5 shows a shape retaining member 11 according to a fourth embodiment, and a convex surface 11a according to the first embodiment.
A groove 11e that divides the center of the convex surface 11a is added to the shape (FIG. 2). With the addition of the groove 11e, the joint 6c at the center of the flat tubes 6, 6 is formed.
Flux can be further improved.

(Fifth Embodiment) FIG. 6 shows a shape retaining member 11 according to a fifth embodiment, in which the shape of the convex surface 11a is changed from a rectangular shape to a wedge shape having a triangular cross section. (Sixth Embodiment) FIG. 7 shows a shape retaining member 1 according to a sixth embodiment.
This is an example in which the shape of the convex surface 11a is a curved surface shape (R shape) formed from a rectangular shape into an arc-shaped cross section.

(Other Embodiments) In the above embodiment, the case where the present invention method is applied to a vehicle heat exchanger is described. However, the present invention is not limited to vehicle heating. It is widely applicable to heat exchangers for various uses, and the case where the electric heating unit 9 is inserted into the space of the predetermined interval K has been described. However, the case where devices other than the electric heating unit 9 are inserted The method of the present invention is also applicable.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of a heating heat exchanger according to a first embodiment of the present invention in an assembled state.

FIG. 2 is a perspective view of the shape retaining member of FIG. 1;

FIG. 3 is a side view of a shape retaining member according to a second embodiment of the present invention.

FIG. 4 is a perspective view showing a main part of a heating heat exchanger according to a third embodiment of the present invention in an assembled state.

FIG. 5 is a side view of a shape retaining member according to a fourth embodiment of the present invention.

FIG. 6 is a perspective view of a main part of a fifth embodiment of the present invention in a state where a heat exchanger for heating is assembled.

FIG. 7 is a perspective view of a main part of a heating heat exchanger according to a sixth embodiment of the present invention in an assembled state.

FIG. 8 is a perspective view of the entire heating heat exchanger according to the prior application.

FIG. 9 is a perspective view of an electric heating unit in the heat exchanger for heating of FIG. 8;

10A is a partially cutaway perspective view of a heating element main body of the electric heating element unit, FIG. 10B is a cross-sectional view of the heating element main body, and FIG. 10C is a longitudinal section of the heating element main body. FIG. 2D is a plan view of the heating element main body.

FIG. 11 is a perspective view of a main part in a state where a heating heat exchanger is assembled according to a conventional method.

[Explanation of symbols]

1, 2 ... tank, 3 ... heat exchange core, 6 ... flat tube, 6c ... joint, 7 ... corrugated fin, 9 ... electric heating element unit, 10 ... fastening member, 11 ... shape retaining member, 11
a: convex surface, 11b: concave surface, 11c: lap portion, 11d
... hollow part, 11e ... groove part.

Claims (4)

[Claims] A joint (6) joined by brazing.
c) and a corrugated fin (7) are alternately assembled, and a shape retaining member (11) having a predetermined width (K) is interposed between the flat tubes (6). A core assembly step of inserting; a flux application step of applying a flux to a surface of an assembly of the flat tube (6) and the corrugated fin (7) after the core assembly step; After the application step, the assembly is heated in a brazing furnace to braze the assembly together, and the shape-retaining member (11) has a heat resistance against a brazing temperature. The shape retaining member (11) is taken out after brazing by being made of a material having the property of not being brazed and having a predetermined width dimension (K) between the flat tubes (6). Form a space A method of manufacturing a heat exchanger, of the shape-retaining member (11), said flat tubes (6)
Is formed as an uneven surface having a convex surface (11a) and a concave surface (11b) extending in a direction perpendicular to the longitudinal direction of the flat tube (6), and the shape retaining member (11) is formed at the convex surface (11a). ) Is in contact with the surface of the flat tube (6). 2. The method for manufacturing a heat exchanger according to claim 1, wherein an electric heating element unit is assembled in a space formed after the shape retaining member is taken out. 3. The flat tube (6) according to claim 1, wherein the convex surface (11a) and the concave surface (11b) are inclined at a predetermined angle (θ) with respect to a direction orthogonal to a longitudinal direction of the flat tube (6). 3. The method for producing a heat exchanger according to item 2. 4. The heat exchanger according to claim 1, wherein a groove (11e) for dividing the convex surface (11a) is formed in the middle of the convex surface (11a). Production method.