JP2000263171A - Manufacture of heat exchanger for heating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a heat exchanger for heating to appropriately set the space of a holding plate in which an electric heating body is inserted. SOLUTION: A manufacturing method of a heat exchanger for heating in which a heat exchanger assembly is formed by integrally brazing a flat tube 6, a holding plate 10 of U-shaped section, and a corrugated fin 7 with each other, and an electric heating body 9 is inserted between two plate surfaces 10c, 10d opposite to each other of the holding plate 10 to form the heat exchanger, has an internal pressure providing process of reducing the spacing of the two plate surfaces 10c, 10d opposite to each other of the holding plate 10 on which the electric heating body 9 is installed to be smaller than the thickness L1 of the electric heating body 9 by the specified quantity by applying the internal pressure into the flat tube 6 before the electric heating body 9 is inserted after the heat exchanger assembly is formed.

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 a heat exchanger for heating in which an electric heating element is integrated.

[0002]

2. Description of the Related Art Heretofore, as a heat exchanger in which an electric heating element of this kind is integrated, the present applicant has filed a Japanese Patent Application No. Hei 9-215.
No. 042 has been filed. The heat exchanger in this application integrates an electric heating element into a heating heat exchanger that heats air using hot water (engine cooling water) as a heat source. By energizing the heating element, the heat generated by the electric heating element can be radiated into the air to heat the air.

[0003]

In a conventional heat exchanger of this type, a holding plate having a U-shaped cross section is provided at an electric heating element arrangement portion between bent portions of adjacent corrugated fins of a heat exchange core portion. And an electric heating element was assembled from the opening of the holding plate. The bent portion of the corrugated fin and the holding plate are assembled together by brazing, and in order to maintain the spacing between the holding plates during brazing,
A brazing dummy plate having the same thickness (L ₁ ) as the electric heating element was inserted.

However, as shown in FIG. 10, a force is applied to the U-shaped holding plate 10 in a direction in which the interval between the openings 10b is enlarged (in the direction of arrow B in FIG. 10) due to the joining force of the brazing material. In operation, the interval between the openings 10b is increased. According to experiments by the present inventors, for example, when the thickness (L ₁ ) of the brazing dummy plate 20 is 1.25 mm, the spread of the opening 10b may be 1.3 to 1.6 mm. Do you get it. As described above, when the opening 10b of the U-shaped holding plate 10 has a thickness equal to or greater than the thickness of the electric heating element, when the electric heating element is inserted between the holding plates 10, the holding plate 10 and the electric heating element can be connected to each other. There is a gap between them. This gap hinders the transfer of heat from the electric heating element to the corrugated fin via the holding plate, so that it has been difficult to improve the thermal efficiency of the heat exchanger.

[0005] Holding plate opening 10b due to the joining force of the brazing material
The thickness of the brazing dummy plate 20 may be made smaller than the thickness of the electric heating element in consideration of the expansion of the gap in advance. However, if the spacing between the holding plates is set in such a manner, as shown in FIG. 11, the electric heating element 9 cannot be inserted all the way into the holding plate. Therefore, the size of the electric heating element 9 is limited to reduce the amount of heat generated, and it is difficult to improve the thermal efficiency of the heat exchanger due to poor adhesion between the holding plate 10 and the electric heating element 9 in the holding plate opening 10b. Met.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method of manufacturing a heat exchanger for heating, in which a distance between holding plates into which electric heating elements are inserted is made appropriate.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a plurality of flat tubes (6) through which a heat source fluid flows and a cross section extending in the longitudinal direction of the flat tubes (6). After arranging the U-shaped holding plate (10) in parallel and arranging a number of flat tubes (6) and corrugated fins (7) between the holding plates (10), the flat tube (6) and the holding The members of the plate (10) and the corrugated fins (7) are integrally brazed to form a heat exchanger assembly (23), and two opposite plate surfaces (10c, 10d) of the holding plate (10). Electric heating element between (9)
In the manufacturing method of the heating heat exchanger manufactured by inserting the heat exchanger, after the heat exchanger assembly (23) is configured, before the electric heating element (9) is inserted, an internal pressure is applied to the flat tube (6). Thereby, the distance between two opposing plate surfaces (10c, 10d) of the holding plate (10) on which the electric heating element (9) is installed is set to a predetermined distance from the thickness (L ₁ ) of the electric heating element (9). It is characterized by having an internal pressure applying step for reducing the pressure.

According to this, by applying the internal pressure, the gap between the openings (10b) is prevented from being enlarged by the joining force of the brazing material acting between the holding plate (10) and the corrugated fin (7). It is possible to do. In particular, the distance between the two facing plate surfaces of the holding plate (10) (10c, 10d), the thickness of the electric heating element (9) by a predetermined amount smaller than (L _1), the internal pressure release after U-shape Holding plate (10)
The distance between the plate surfaces (10c, 10d) can be set to an appropriate distance by the springback force. Therefore, it is possible to reduce a gap between the electric heating element (9) and the holding plate (10) which is generated when the electric heating element (9) is inserted between the holding plates (10).

According to a second aspect of the present invention, the heat exchanger assembly (23) is externally pressed during the internal pressure applying step. According to this, an external pressure is applied from the outside in a direction that suppresses the expansion of the heat exchanger assembly (23), and an internal pressure is applied inside the flat tube (6), whereby the heat exchanger assembly ( 23) is expanded
Deformation can be prevented.

According to the third aspect of the present invention, the pressing dummy plate (21) for setting the interval between two opposing plate surfaces (10c, 10d) of the holding plate (10) to a predetermined value is provided.
After being inserted between the two plate surfaces (10c, 10d), an internal pressure applying step is performed. According to this, the pressing dummy plate (21) makes it possible to suppress excessive deformation of the holding plate (10) due to the internal pressure.

According to a fourth aspect of the present invention, the pressing dummy plate (21) has a thickness (L ₄ ) smaller than the electric heating element (9) by a predetermined amount. According to this, it becomes easy to change the distance between the holding plates (10) to a desired size by the internal pressure. In addition, the code | symbol in the parenthesis of each said means shows the correspondence with the concrete means described in embodiment mentioned later.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 5 show a first embodiment of a vehicle heating heat exchanger to which the present invention is applied. In FIG. 1, a heating heat exchanger H includes 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 through which hot water (engine cooling water) from a vehicle engine (not shown) flows in, 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 symmetrical as shown in FIG. 1, the hot water inlet side tank 1 and the hot water outlet side tank 2 may be reversed left and right.

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 faces of the tank main bodies 1a and 2a, and has a well-known tank structure in which the vertical direction in FIGS. A large number of flat tube insertion holes (not shown) are formed in the sheet metals 1b and 2b, and one or more rows are formed in the vertical direction in FIGS.

The heat exchanging core portion 3 includes a plurality of flat tubes 6 formed in a flat shape parallel to the flow direction of the air for heating (the direction of arrow A in FIG. 1). Have been placed. Corrugated fins (fin members) 7 formed in a wave shape are arranged and joined between the plurality of flat tubes 6. This corrugated fin 7
As is well known, a large number of louvers (not shown) are cut and raised obliquely at a predetermined angle with respect to the flow direction A of the heating air, and the fins improve the fin heat transfer coefficient. .

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 provided further outside the corrugated fins 7 on the outermost sides (upper and lower ends in FIG. 1) of the core portion 3, and these side plates 8a and 8b are disposed.
8b is joined to the outermost corrugated fin 7 and sheet metal 1b, 2b.

Further, instead of the flat tube 6, an electric heating element 9 is provided at a part of the heat exchange core portion 3. In the example of FIG. 1, electric heating elements 9 are installed at equal intervals at four locations (hatched portions) of the heat exchange core 3. In the heat exchange core portion 3, at the portion where the electric heating element 9 is installed, between the bent top portions of the adjacent corrugated fins 7, a holding plate 10 having a U-shaped cross section extending in the longitudinal direction of the flat tube 6. Has been arranged. As shown in FIGS. 2 and 3, the closed end 10 a of the holding plate 10 having a U-shaped bent shape faces the air inlet side of the heat exchange core 3, and the opening 10 b on the other end is used for heat exchange. The arrangement direction of the holding plate 10 is set so as to face the air outlet side of the core portion 3.

The holding plate 10 sets a predetermined distance L ₁ between two opposing plate surfaces 10 c and 10 d,
In this state, the two plate surfaces 10c and 10d are joined to the bent tops of the corrugated fins 7, respectively. The electric heating element 9 is connected to the holding plate 10 through the opening 10b.
It is inserted and held inside. Here, the electric heating element 9
The thickness of the is set to the same as above L _1. The electric heating element 9 is electrically insulated and held by the holding plate 10 by a structure described later.

Since the entire thickness L ₂ of the holding plate 10 is set to be the same as the thickness L _{3 of} the flat tube 6, the holding plate 10 is replaced with the adjacent corrugated fin 7 instead of the flat tube 6. Can be installed between In FIG. 3, D is the thickness of the core, which is the dimension of the flat tube 6 and the corrugated fin 7 in the air flow direction A. By the way, in the heat exchanger in this example, all of the components 1 to 8b are formed of aluminum (including an aluminum alloy), and the holding plate 10 having a U-shaped cross section is also formed of aluminum. Is molded. The holding plate 10 has a thickness of 0.1 to
The width of the flat holding plate 10 (width in the heating air flow direction A) is substantially the same as the thickness D of the core portion. (Size in the left-right direction in FIG. 1) is substantially the same as the size between the sheet metals 1b and 2b.

The electric heating element 9 has a structure as shown in FIGS. 2 and 3 and has a rectangular or disc-shaped heating element 9a and an elongated flat plate disposed on both front and back surfaces of the heating element 9a. And a three-layer sandwich structure composed of the electrode plates 9b and 9c. A covering member 9d made of an electrically insulating material is provided around the entire periphery of the electrode plates 9b and 9c.
Covered by Here, the heating element 9a is a PTC heater element made of a resistor material (for example, barium titanate) having a positive resistance temperature characteristic whose resistance value rapidly increases at a predetermined set temperature (for example, around 200 ° C.) T0. And the plate thickness is about 1.0 to 2.0 mm.

The two electrode plates 9b and 9c of the heating element 9a are formed of a conductive metal material such as aluminum, copper, and stainless steel, and have a thickness of about 0.1 to 0.5 mm.
The dimensions in the longitudinal direction (the dimensions in the left-right direction in FIG. 1) of the two electrode plates 9 b and 9 c are substantially the same as those of the holding plate 10. The heating element 9 is arranged in the longitudinal direction of the two electrode plates 9b and 9c.
a is arranged at a plurality of locations. The heating element 9a and the two electrode plates 9b and 9c are brought into pressure contact with each other so that electrical conduction between them is obtained.

The coating member 9d is provided on the plate surface 10c of the holding plate 10,
The electric heating element 9 is assembled inside the holding plate 10 so as to be in pressure contact with the inner surface of 10d. Here, the covering member 9d functions to electrically insulate the holding plate 10 and the two electrode plates 9b and 9c, but plays a role of conducting the heat of the heating element 9a to the holding plate 10. , Holding plate 10
The thickness of the covering member 9d between the electrode member 9b and the electrode plate 9c is 2
A good heat conduction effect is ensured by forming a thin film of about 5 to 100 μm.

On the other hand, the thickness of the covering member 9d on the side of the heating element 9a is increased to about 1 to 2 mm to protect the heating element 9a. As a specific material of the covering member 9d, a resin having high heat resistance (for example, polyimide resin or the like) is preferable. The electrode plate 9b is a positive electrode plate, and the electrode plate 9c is a negative electrode plate, and terminals 9e and 9 for electrical connection to an external circuit are provided, respectively.
f is integrally formed. In the present embodiment, the terminal portions 9e and 9f protrude rearward of the heat exchange core portion 3 (downstream in the air flow direction A). The terminal 9e of the positive electrode plate 9b is formed at the right end of the positive electrode plate 9b as shown in FIG. 1, and the terminal 9f of the negative electrode plate 9c is formed at the left end of the negative electrode plate 9c. Is formed.

The electrode plates 9b, 9c of each electric heating element 9
An external control circuit (not shown) is electrically connected to the terminal portions 9e and 9f integrally formed with the power supply unit, and power is supplied to each electric heating element 9 from a vehicle-mounted power supply via the external control circuit. Here, the terminal portions 9e and 9f may be joined to the electrode plates 9b and 9c by welding or the like instead of being integrally formed.

Reference numerals 12 and 13 denote fastening (band) members made of a metal material having excellent corrosion resistance such as stainless steel.
The heat exchange core 3 is arranged on both the air inlet side surface and the air outlet side surface. Each of the fastening members 12 and 13 has a hook portion formed in a bent shape at both ends thereof, and this hook portion is provided with locking grooves 8c and 8d formed at the longitudinal center portions of the upper and lower side plates 8a and 8b. And attached between the upper and lower side plates 8a and 8b. By mounting the fastening members 12 and 13, a tightening force for pressing and holding the electric heating element 9 between the plate surfaces 10 c and 10 d of the holding plate 10 is applied to the heat exchange core 3. In FIG. 1, the fastening members 12 and 13 are attached to only one central portion in the width direction of the core portion 3 (the left-right direction in FIG. 1). It goes without saying that 12, 13 may be attached.

Since the holding plate 10 has the closed end 10a having a U-shaped bent shape, the holding and fixing of the electric heating element 9 can be performed only by installing the fastening member 12 only on the opening 10b side. It becomes possible. Next, a method of manufacturing the above-described heating heat exchanger will be described. First, a core assembling step of assembling the heat exchanger configuration shown in FIG. 1 is performed. That is, the tubes 6 and the corrugated fins 7 of the heat exchange core portion 3 are alternately laminated, and the portion of the heat exchange core portion 3 where the electric heating element 9 is installed (the four hatched portions in FIG. 1). In this embodiment, a holding plate 10 having a U-shaped cross section extending in the longitudinal direction of the tube 6 is arranged between the bent tops of the adjacent corrugated fins 7. At this point, the opposite 2
One plate surface 10c, to hold the spacing 10d at predetermined intervals L _1, the interior of the holding plate 10, this predetermined distance L ₁
A brazing dummy plate 20 having a thickness of 3 mm is inserted.

The brazing dummy plate 20 has a heat resistance to an integral brazing process described later, and has a property not to be brazed with aluminum (for example, aluminum brazing).
(Carbon or the like). In this assembly process, the tanks 1, 2, the pipes 4, 5, and the side plates 8a, 8
It goes without saying that b is also assembled. Next, as described above, the assembled state of the assembled heat exchanger assembly is held by an appropriate jig (not shown), carried into a brazing furnace, and a brazing step is performed. That is, the heat exchanger assembly is heated to a brazing temperature (about 600 ° C.) in a brazing furnace to melt the brazing material of the aluminum clad material of each member of the heat exchanger. Are brazed together.

After the brazing, the heat exchanger assembly is carried out of the brazing furnace. Then, after the temperature of the heat exchanger assembly has dropped to room temperature, the brazing dummy plate 20 and the pressing plate 21 are replaced as shown in FIG.
The pressing dummy plate 21 is for preventing the holding plate 10 from being excessively deformed when a pressing / internal pressure is applied in a later-described process.

As shown in FIG. 5, a dummy plate for pressing
21 plate thickness L_FourIs the cross-section when pressing / internal pressure release is released
Considering the springback force of the U-shaped holding plate 10,
Thickness L of brazing dummy plate₁Slightly smaller than
Is set. As an example of the present embodiment, brazing
Thickness of the dummy plate, ie, the thickness L of the electric heating element 9 ₁
Is 1.25 mm, the pressing dummy plate 21
Sheet thickness L_FourIs set in the range of 1.0 to 1.2 mm.

The pressing dummy plate 2 is provided between the holding plates 10.
After inserting 1, the pressing / internal pressure is applied to the heat exchanger assembly 23 assembled by integral brazing by the pressing / internal pressure applying device 22 shown in FIG. In FIG. 6, the pedestal 24
Is for mounting the heat exchanger assembly 23. The pedestal 24 has backing plates 25 and 26 for preventing deformation of the heat exchanger assembly 23 in the width direction (the left-right direction in FIG. 1) and the height direction of the heat exchanger assembly 23 (FIG. 1). (Up and down directions) are provided. The caul plates 25 and 26 and the caul plates 27 and 28 form a pair.

The backing plate 26 is fixed to the pedestal 24,
On the other hand, the backing plate 25 is movable in the width direction of the heat exchanger assembly 23. Then, after setting the heat exchanger assembly 23 on the pedestal 24, the heat exchanger assembly 23 is pressed and fixed in the width direction by an adjusting screw 29 for adjusting the load applied to the backing plate 25. Similarly, the backing plate 28 fixed to the pedestal 24 also extends in the height direction of the heat exchanger assembly 23.
Adjustment screw 31 in the direction of
To apply a load. Note that the pressing load is performed while checking with the pressing gauges 30 and 32.

The hose 33 is connected to the inlet pipe 4,
This is for allowing air to flow into the tube 6. The outlet pipe 5 is plugged with a sealing cap 34 to prevent the outflow of the inflow air in order to emphasize the air in the tube 6 and apply the internal pressure to the heat exchanger assembly 23. Air for applying internal pressure is supplied to the hose 33 by a valve 35.
Is provided, and the amount of inflow air can be adjusted by opening and closing the valve. The internal pressure due to the inflow air is checked while checking with a pressure gauge provided in the hose 33. It is needless to say that the air to which the internal pressure is applied may flow in from the outlet pipe 5 and flow out from the inlet pipe 4.

The pressing / internal pressure stroke of the heat exchanger assembly 23 by the pressing / internal pressure applying device 22 will be described below. The heat exchanger assembly 23 with the pressing dummy plate 21 inserted between the holding plates 10 is set on the pedestal 24. After the setting, as shown in FIG. 7, a pressing load is applied in the width direction of the heat exchanger assembly 23 by the contact plates 26 and 27.
At the same time, a pressing load is applied in the height direction of the heat exchanger assembly 23 by the contact plates 27 and 28.

After applying a pressing load in the width direction and the height direction of the heat exchanger assembly 23, as shown in FIG.
The hose 33 is connected to the inlet pipe 4 while pressing by 5-28, and the outlet pipe 5 is plugged with the sealing cap 34. Then, the valve 35 is opened to allow air to flow into the tube 6 of the heat exchanger assembly 23. The connection of the hose 33 to the inlet pipe 4 and the sealing of the outlet pipe 5 with the sealing cap 34 may be performed before the pressing stroke.

The magnitude of the load of the pressing and the internal pressure is as follows.
Mutual relationship between internal pressure and external pressure, and heat exchanger assembly 23
Is determined in consideration of the strength of In the present embodiment, the pressing load is 200 to 600 N which is a pressure that does not cause the heat exchanger assembly 23 to buckle inward, and the internal pressure load is 150 kPa which is equal to or less than the pressure resistance strength (490 kPa) of the heat exchanger assembly 23. ~
It is pressurized at 300 kPa.

When air is caused to flow into the tube 6 by the internal pressure applying step, the tube 6 expands and deforms due to the pressure. And for the deformation of the tube 6,
Opposite two plate surfaces 10c, 10 of the U-shaped holding plate 10
d It is pushed in the direction in which the interval between them becomes smaller. Between the holding plate 10 of U-shaped, pressing dummy plate 21 of the plate thickness L ₄
There since have been inserted, the deformation of the holding plate 10 is suppressed to plate thickness L ₄ of the pressing dummy plate.

After the pressure between the U-shaped holding plates 10 becomes L ₄ equal to the plate pressure of the pressing dummy plate 21 due to the internal pressure,
The inflow of air from the inlet pipe 4 is stopped, and the sealing cap of the sealing cap 34 is released. Then, after the internal pressure is released, the pressing by the contact plates 25 to 28 is released.
After releasing the internal pressure and the pressing, the heat exchanger assembly 23 is removed from the pressing / internal pressure applying device 22. Then, as shown in FIG. 9, the pressing dummy plates 21 inserted inside the four holding plates 10 of the heat exchanger assembly 23 are removed.

Removed from the pressing / internal pressure applying device 22,
After the pressing dummy plate 21 is removed, a springback force acts on the U-shaped holding plate 10 so that the holding plate 1
0 of the opening portion 10b extends from the L _4. However, in this embodiment, the holding plate 10 is formed of aluminum having a thickness of 0.1 to 0.5 mm, and the distance between the plate surfaces 10 c and 10 d of the holding plate 10 is set to 1.0 to 1.2 mm in the pressing / internal pressure applying step. And As a result, the holding plate 1 is
The distance between the zero plate surfaces 10c and 10d can be set to about 1.25 mm, which is the thickness of the electric heating element 9.

Next, a step of assembling the electric heating element 9 is performed. That is, the electric heating element 9 alone is used as the heat exchanger assembly 2.
Separately from the above, the front and back surfaces of the plate-shaped heating element 9a are sandwiched between the plate-shaped electrode plates 9b and 9c to form a three-layer sandwich structure, and the periphery of the electrode plates 9b and 9c is covered by a covering member 9d over the entire circumference. Cover. Then, after removal of the pressing dummy plate 21, two plate surfaces 10c facing the retaining plate 10, a space of a predetermined distance L ₁ that is formed on the inside of the 10d, the direction from the opening 10b to the closed end 10a side To insert the electric heating element 9. At this time, the electric heating element 9 is assembled in the holding plate 10 so that the covering member 9 d is pressed against the holding plate 10. Thereby, the heat exchange core portion 3 is formed.

After the electric heating element 9 is assembled, the hooks at both ends of the fastening members 12 and 13 are connected to the upper and lower side plates 8.
The fastening members 12 and 13 are fitted between the upper and lower side plates 8a and 8b so that the heat exchange core 3 is compressed by being hooked on the locking grooves 8c and 8d. Thus, a tightening force for pressing and holding the electric heating element 9 inside the holding plate 10 is applied to the heat exchange assembly 23, so that the electric heating element 9 can be reliably held and fixed inside the holding plate 10.
At the same time, inside the electric heating element 9, both the front and back surfaces of the heating element 9a are reliably pressed against the flat electrode plates 9b and 9c, so that a good electric conduction state can be obtained with a small contact resistance.

Since the heating element 9a of the electric heating element 9 is a PTC element having a positive resistance temperature characteristic whose resistance value rapidly increases at a predetermined set temperature T0, as is well known, the heat generation temperature is set to the set temperature. A self-temperature control function for self-control at T0 is provided. . In the present embodiment, in order to match the distance between the holding plates 10 before inserting the electric heating elements 9 with the distance between the electric heating elements 9, the heat exchanger assembly 23 is integrally brazed and then placed between the holding plates 10. The pressing dummy plate 21 is inserted to apply internal pressure and pressure. This dummy plate 2
The thickness L ₄ of the first heating element 9 is set slightly smaller than the thickness L ₁ of the electric heating element 9.

With the dummy plate 21 inserted between the holding plates 10, internal pressure and pressure are applied to
While preventing excessive deformation of the holding plate 10, the distance between the opening 10b of the holding plate 10 can be L _4. And
After releasing the pressure-pressed, by spring back force of the holding plate 10 of the U-shape, expanded interval of the opening 10b of the holding plate 10, to be approximately equal to the thickness L ₁ of the electrical heating element 9 it can.

For this reason, when the electric heating element 9 is inserted into the holding plate 10, the gap between the electric heating element 9 and the two plate surfaces 10c and 10d of the holding plate 9 facing each other can be reduced, resulting in poor adhesion. Can be reduced. As a result, the electric heating element 9
Can be efficiently transmitted to the corrugated fins 7. In the present embodiment, when the internal pressure is applied, the pressing is also performed. However, when the swelling of the core portion 3 due to the application of the internal pressure is small, the pressing step can be omitted.

In the present embodiment, air is introduced into the tube 6 to apply internal pressure. However, it goes without saying that the internal pressure may be applied by means other than air. For example, a fluid such as water or helium can be used. That is, any means may be used as the means for applying the internal pressure as long as no impurities remain in the core portion 3 when the internal pressure is removed.

Further, in the above embodiment, the heat exchanger for heating a vehicle has been described. However, the present invention is not limited to the heat exchanger for a vehicle, but can be widely applied to heat exchangers for various purposes. Further, the installation form of the electric heating element 9 is not limited to the form shown in FIG. 1, and it is needless to say that various changes can be made in response to changes in the specifications of the heating heat exchanger.

[Brief description of the drawings]

FIG. 1 is a perspective view of a heat exchanger for heating showing an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of an electric heating element installation portion of FIG.

FIG. 3 is a cross-sectional view of an electric heating element installation portion of FIG.

FIG. 4 is a diagram illustrating a process of inserting a pressing dummy plate according to the embodiment of the present invention.

FIG. 5 is a sectional view of a holding plate and a pressing dummy plate according to the embodiment of the present invention.

FIG. 6 is a perspective view of a pressing / internal pressure applying device according to the embodiment of the present invention.

FIG. 7 is a diagram illustrating a pressing application step according to the embodiment of the present invention.

FIG. 8 is a diagram showing an internal pressure applying step according to the embodiment of the present invention.

FIG. 9 is a diagram illustrating a step of taking out a pressing dummy plate according to the embodiment of the present invention.

FIG. 10 is a cross-sectional view of a conventional holding plate and a brazing dummy plate.

FIG. 11 is a sectional view of a conventional holding plate and a brazing dummy plate.

[Explanation of symbols]

1, 2, tank, 3 heat exchange core, 6 flat tube, 7 corrugated fin, 9 electric heating element, 9a heating element, 9b, 9c electrode plate, 9d coating member, 9
e, 9f: terminal portion, 10: holding plate, 10a: closed end portion,
10b: Opening, 10c, 10d: Plate surface, 10e: Stopper, 10f: Stopper member, 10g: Reinforcement rib, 12, 13: Fastening member.

Claims (4)

[Claims] 1. A plurality of flat tubes (6) through which a heat source fluid flows and a holding plate (10) having a U-shaped cross section extending in the longitudinal direction of the flat tubes (6) are arranged in parallel. After disposing a corrugated fin (7) between the flat tube (6) and the holding plate (10), the members between the flat tube (6), the holding plate (10) and the corrugated fin (7) To form a heat exchanger assembly (23), and two opposite plate surfaces (10c, 1c) of the holding plate (10).
0d). A method of manufacturing a heating heat exchanger manufactured by inserting an electric heating element (9) during 0d), wherein after the heat exchanger assembly (23) is constructed, the electric heating element (9) is inserted. Before, by applying an internal pressure to the inside of the flat tube (6), two opposite plate surfaces (10c, 10c) of the holding plate (10) on which the electric heating element (9) is installed.
A method for producing a heat exchanger for heating, characterized by comprising an internal pressure applying step in which the interval d) is made smaller than the thickness (L ₁ ) of the electric heating element (9) by a predetermined amount. 2. The method for manufacturing a heat exchanger for heating according to claim 1, wherein the heat exchanger assembly (23) is externally pressed during the internal pressure applying step. 3. A pressing dummy plate (21) for setting a distance between two opposing plate surfaces (10c, 10d) of the holding plate (10) to a predetermined value is provided on the two plate surfaces (10c, 10d).
The method for manufacturing a heat exchanger for heating according to claim 1 or 2, wherein the step of applying the internal pressure is performed after being inserted during d). 4. The heating heat exchanger according to claim 3, wherein the pressing dummy plate (21) has a thickness (L ₄ ) smaller than the electric heating element (9) by a predetermined amount. Production method.