JP2597141B2 - Heat exchanger manufacturing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a heat exchanger used as, for example, an evaporator of a heating device, and more particularly to a method of flowing in a flat tube by combustion heat of an oil burner or a gas burner. The present invention relates to a method for manufacturing a heat exchanger used as an evaporator for evaporating a heat medium such as freon.

In this specification, the term “aluminum” includes an aluminum alloy in addition to pure aluminum.

2. Description of the Related Art Conventionally, as shown in FIG. 11, through holes (51) extending in the axial direction of a main body (50) are formed in a peripheral wall of a cylindrical combustion chamber main body (50) made of an extruded aluminum material as shown in FIG. ) Are formed at predetermined intervals in the circumferential direction, and the straight pipe portions of the plurality of hairpin heat-insulating medium flowing pipes (52) are inserted into adjacent through holes (51), and each hairpin-shaped heat medium flowing pipe is formed. (52) connected by a U-shaped connecting pipe (53) was used.

Problems to be Solved by the Invention However, in the above-described conventional heat exchanger, the flow path of the heat medium is bent into a U-shape at the bent portion of the heat medium flow pipe (52) and the connecting pipe (53). Therefore, there is a problem that the pressure loss increases. Further, there is a problem that the area of the heat medium passage is small.

Therefore, the present applicant firstly has an aluminum cylindrical combustion chamber main body and a plurality of heat medium flow passages therein, and the heat medium flow passages extend in the circumferential direction or the axial direction of the combustion chamber main body. A heat exchanger provided with an aluminum arc-shaped flat tube closely adhered to the outer peripheral surface of the combustion chamber main body and brazed to the combustion chamber main body was proposed (Japanese Utility Model Application No. 61-192206).
With this heat exchanger, the above-mentioned problems of the conventional heat exchanger can be solved, but the following problems are considered to occur. That is, it is actually difficult to completely braze the outer peripheral surface of the combustion chamber main body and the flat tube, and it is inevitable that a minute gap is formed between the two. When pitting occurs on the wall of the flat tube on the side of the combustion chamber main body, a heat medium such as freon leaks and enters the gap, which causes pitting in the combustion chamber main body. As a result, the freon enters the combustion chamber body, and the freon and the combustion gas react to generate toxic gas.

An object of the present invention is to provide a method for manufacturing a heat exchanger that solves all of the above problems.

Means for Solving the Problems A method for manufacturing a heat exchanger according to the present invention includes an aluminum combustion chamber main body, an aluminum heat chamber having a plurality of heat medium passages therein, and brazed to an outer surface of the combustion chamber main body. A method of manufacturing a heat exchanger including a flat tube, wherein a zinc plating layer is previously formed on surfaces of an aluminum combustion chamber main body and an aluminum flat tube, and the aluminum combustion chamber main body and the aluminum flat tube are formed. And brazing.

According to the method of the present invention, zinc is diffused into aluminum by heating the combustion chamber main body, the flat tube, and the brazing, thereby forming a zinc diffusion layer. Then, the zinc diffusion layer is sacrificed to the surface of the aluminum, and the pitting corrosion of the flat tube and the combustion chamber main body is prevented for a long time.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, front and rear refer to the direction of flow of the combustion chamber body, front refers to the direction indicated by the arrow (A) in FIG. 1, and rear refers to the opposite side. In addition, the upper and lower sides refer to the upper and lower sides in FIGS. 1, 2, and 5 to 8. Further, the left and right refer to the left and right in FIGS. 2 and 6 to 8.

1 to 3 show an example of a heat exchanger manufactured by the method of the present invention. 1 to 3, the heat exchanger (1) comprises a top wall portion (2) and left and right side wall portions (3) extending downward from the left and right side edges of the top wall portion (2). An aluminum combustion chamber main body (4) opened downward and an aluminum lid (5) fixed to the front and rear ends of the combustion chamber main body (4) to close the front and rear ends of the combustion chamber main body (4); It has two aluminum corrugated fins (6) disposed between the side walls (3) and brazed to the left and right side walls (3), respectively, and a large number of heat medium flow passages (8) inside, And two aluminum flat tubes (7) brazed to the outer surfaces of the left and right side walls (3), respectively, and aluminum straight tubular headers (9) brazed to both ends of both flat tubes (7). It has.

The top wall portion (2) of the combustion chamber main body (4) has an arc shape whose central portion protrudes upward. The left and right side wall portions (3) are continuous with the left and right side edges of the top wall portion (2), have the same radius of curvature as the top wall portion (2), and have an arc-shaped portion (11) whose central portion protrudes outward. And a vertical portion (12) extending downward from the lower edge of the arc-shaped portion (11). And the top wall (2)
And the arc-shaped portions (11) of the left and right side walls (3) are formed to have a circular cross section. In addition, vertical part (12)
An outer horizontal bent portion (13) is integrally provided at the lower edge of the lower portion.

A portion (14) of a U-shaped cross section is provided on a portion of the entire periphery of the lid (5) except for the lower edge, and the holding portion (14) is used to form the combustion chamber body (4). ) Is fixed to the combustion chamber body (4) by clamping the front and rear ends. The lid (5) at the front end has an opening for oil burner insertion (15).
Are formed.

The corrugated fin (6) is arranged so that its flat part is on a vertical plane perpendicular to the front-rear direction.

The flat tube (7) has left and right side walls such that the heat medium flow passage (8) extends in the circumferential direction of the arc-shaped portion (11) of the top wall portion (2) and the left and right side wall portions (3). Part (3) is brazed in close contact with the outer surface. The upper and lower ends of the flat tube (7) are bent outward so as to be horizontally directed, and the ends thereof are connected to the header (9). The bent portion is indicated by (16). Further, among all the partition walls (17) partitioning the adjacent heat medium flow passages (8) of the flat tube (7), a plurality of partition walls at predetermined intervals in the front-rear direction are more than others. It is made thick. Thick bulkheads are indicated by (17A).

The lower head (9) is an inlet-side header, and the front end and the rear end are connected by a pair of front and rear aluminum tubular connection members (18) each having a substantially U shape when viewed from a plane. (9) and connecting member (18)
Thus, it is formed in a rectangular shape that is long in the front and back when viewed from a plane. The heat medium inlet pipe (19) is connected to the front connection member (18), and the oil drain pipe (21) is connected to the rear connection member (18). The upper header (9) is an outlet header, and its rear end is connected to an aluminum collecting pipe (22) extending in the left-right direction and having both ends closed. The front end of the outlet header (9) is closed. The heat medium outlet pipe (23) is connected to the collecting pipe (22). An elongated hole (24) extending in the axial direction is formed on the peripheral wall of each of the headers (9), and the front end bent portion (16) of the flat tube (7) passes through the elongated hole (24) to the header. (9) and brazed to the peripheral wall of the header (9). Tubular connecting member (18) and collecting pipe (22)
After forming a thin zinc film by immersion in a galvanizing bath in a non-energized state, a zinc plating layer is formed on the surface of the material for forming an electroplating method using a galvanizing bath similar to the above. It is preferable to form the film and then perform a corrosion-resistant treatment for diffusing zinc by heating the film.

FIG. 4 shows a heating device using the heat exchanger (1) as an evaporator.

The heating device uses, for example, freon as a heat medium, and includes an indoor unit (26) and an outdoor unit (27). The indoor unit (26) has a condenser (31) and a blower (32) provided in a casing (30) having an air inlet (28) and an air outlet (29). The heat exchanger (1) is disposed in the casing (33) of the outdoor unit (27), and has an inlet header (9), an outlet header of the condenser (31), and an outlet header (9). And the inlet header of the condenser (31) are connected by conduits (34) and (35), respectively. In the casing (33) of the outdoor unit (27), a check valve (36) and a receiver (37) are located in the middle of one conduit (34).
Are provided in this order from the condenser (31) side. A check valve (38) is provided in the middle of the other conduit (35). An oil burner (39) is disposed in the combustion chamber body (4) of the heat exchanger (1), and the heat medium flowing through the flat tube (7) is heated and vaporized by the combustion heat of the burner (39). It has become. An exhaust gas pipe (not shown) whose tip extends to the outside of the casing (33) is connected to the lower end opening of the combustion chamber body (4) so that the exhaust gas is released to the atmosphere by the exhaust gas pipe. It has become.

In such a configuration, the combustion gas of the oil burner (39) flows downward through the space between the fins (6) between the left and right side walls (3). The heat medium flowing in the flow passage (8) of the flat tube (7) is heated and vaporized by the combustion heat of the oil burner (39) and sent to the condenser (31) through the conduit (35). Then, while passing through the condenser (31), the blower (3
2) The heat is radiated and liquefied to the room air sucked into the casing (30) through the suction port (28) through the suction port (28), and is passed through the conduit (34) to the inlet-side header (9) of the heat exchanger (1). Sent.
The air that has taken heat from the heat medium passing through the condenser (31) in the casing (30) is blown into the room from the outlet (29), and the room is heated by the air.

Hereinafter, the method of manufacturing the heat exchanger (1) will be described in the fifth.
This will be described with reference to FIGS.

A plate-shaped combustion chamber body material (41) made of an aluminum brazing sheet whose upper surface is previously covered with an aluminum brazing material layer (42) as shown in FIGS. 5 and 6, a flat tube (7), a corrugate A fin (6) and a tubular header (9) are prepared. At the center of the width of the combustion chamber body material (41), a ridge (43) having a substantially inverted W-shaped cross section is formed to protrude upward and open downward over the entire length.
From the lower end of the left and right side walls of the ridge (43) to the left and right side edges of the top wall, respectively, the same radius of curvature as the arc-shaped portion (11) in the left and right side walls (3) of the combustion chamber main body (4) and Part (44) to be an arc-shaped part (11) having the same arc length
Are formed. The two arc-shaped portions (44) are connected to each other in a downwardly concave and upwardly open cross-section arc-shaped connecting wall (45).
Are connected by This connecting wall (45) is a portion to be the top wall (2) of the combustion chamber body (4). The combustion chamber body material (41) is immersed on both sides of a flat brazing sheet in a galvanizing bath with no current applied, and an ultra-thin zinc film (4
After forming (0) (pre-zinkate treatment) (see FIG. 9), a galvanized layer (49) is formed on the zinc film (40) by an electroplating method using a galvanizing bath similar to the above (see FIG. 9). It is formed by bending. As in the case of the combustion chamber body material (41), the flat tube (7) is immersed in a galvanizing bath in a non-energized state on the surface of a straight extruded material to form an extremely thin zinc film ( Pre-zincate treatment), a galvanized layer is formed by an electroplating method using the same zinc plating bath as above,
Then, it is formed by bending. The inner surface and the outer surface of the tubular header (9) are made of an aluminum brazing layer (46).
A long hole is formed in the peripheral wall of an electric resistance welded tube made of a brazing sheet covered with.

The composition of the galvanizing bath used for the pre-zincate treatment is as follows: ZnO: 5 to 15 g /, NaOH: 50 to 150 g /, brightener:
Preferably it is 3 to 10 ml /. As the brightener, for example, aminoaldehyde and heliotropin are preferably used. The immersion time in the galvanizing bath is preferably about 15 to 90 seconds. The temperature of the galvanizing bath is preferably about 25 to 30 ° C. The pre-zincate treatment removes the oxide film on the surface of the aluminum material and substitutes it to deposit zinc, so that an ultra-thin zinc film (40) is uniformly and well adhered to the aluminum material surface. It is formed.

The electroplating treatment is preferably performed using a plating bath having the same composition and the same liquid temperature as the pre-zincate treatment. The thickness of the plating layer (49) formed by electroplating is 0.3
It is preferably about 8 μm.

After forming the galvanized layer (49) as described above,
The header (9) was put on both ends of the flat tube (7) so that both ends of the flat tube (7) were fitted into the elongated holes (24). Next, the flat tube (7) extends along the horizontal portion (47) on both sides of the ridge (43) on the upper surface of the material (41) from the arc-shaped portion (44). In addition, corrugated fins (6)
Along the plate brazing material (48) of the horizontal part (47) of the material (41). Then, the material (41), the flat tube (7), the header (9), and the fin (6) are fixed with a jig (not shown).

Thereafter, the combustion chamber body material (41) and the flat tube (7), the flat tube (7) and the header (9), and the combustion chamber body material (41)
And the fins (6) are brazed, respectively (see FIG. 7). The zinc plating layer (49) formed on the material (41) and the header (9) by the heating during the brazing process.
Is diffused into aluminum to form a zinc diffusion layer for corrosion protection.

Further, the combustion chamber body material (41) is bent downward by the connecting wall (44), and the connecting wall (44) is used as the top wall (2), and the arc-shaped portion (44) and the horizontal portion (47) are on both left and right sides. The wall (3) is used (see FIG. 8). Finally, the lid (5) is swaged to the front and rear ends of the combustion chamber body (4), and the connecting member (18), the heat medium inlet pipe (19), the collecting pipe (22), and the heat medium outlet pipe (23) are connected. Join. Thus, the heat exchanger (1) is manufactured.

In the above embodiment, the method of the present invention is applied to the manufacture of a heat exchanger using a petroleum burner, but can also be applied to the manufacture of a heat exchanger using a gas burner. The shapes of the combustion chamber body and the flat tubes of the heat exchanger using the gas burner are different from the shapes of the combustion chamber body and the flat tubes of the heat exchanger using the oil burner. Change it slightly to suit your needs.

Effect of the Invention According to the method of the present invention, zinc is diffused into aluminum by heating during brazing of the combustion chamber main body and the flat tube, and a zinc diffusion layer is formed. Then, the zinc diffusion layer is sacrificed to the surface of the aluminum, and the pitting corrosion of the flat tube and the combustion chamber main body is prevented for a long time. Therefore, a heating medium such as freon flowing through the flat tube is prevented from entering the combustion chamber main body and reacting with freon and the combustion gas. As a result, generation of toxic gas due to the reaction between the freon and the combustion gas is prevented. You.

A heat exchanger manufactured by the method of the present invention is an aluminum flat plate having an aluminum combustion chamber main body, a plurality of heat medium flow passages therein, and brazed to outer surfaces of left and right side walls. Because it has a tube,
The area of the heat medium passage is much larger than that of the conventional one shown in FIG. Further, since the number of bent portions of the flow passage is reduced as compared with the conventional one shown in FIG. 11, the pressure loss is reduced. Therefore, the heat exchange efficiency is improved as compared with the conventional one shown in FIG.

[Brief description of the drawings]

1 is a perspective view of a heat exchanger manufactured by the method of the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a sectional view taken along the line III-III of FIG. FIG. 4 is a schematic view showing a heating apparatus using the heat exchanger manufactured by the method of the present invention, FIGS. 5 to 10 show the method of the present invention,
FIG. 5 is a perspective view showing an arrangement state of each part for the heat exchanger before brazing, FIG. 6 is a sectional view of the same, and FIG. 7 is a sectional view showing a state of each part for the heat exchanger after brazing. FIG. 8 is a cross-sectional view showing a state in which the material of the combustion chamber body is bent, FIG. 9 is a partially enlarged cross-sectional view of the combustion chamber body material before brazing before being subjected to a pre-zincate treatment, and FIG. FIG. 11 is a partially enlarged cross-sectional view of a combustion chamber body material after the treatment, and FIG. 11 is a perspective view showing a conventional example. (1) ... heat exchanger, (4) ... combustion chamber body, (7) ...
... flat tube, (8) ... heat medium flow passage, (49) ... galvanized layer.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 1-271063 (JP, A) JP-A 64-15276 (JP, A) JP-A 62-240158 (JP, A) JP-A 62-240 97767 (JP, A) Actually open 63-97066 (JP, U)

Claims (1)

(57) [Claims] A method for manufacturing a heat exchanger comprising an aluminum combustion chamber main body and an aluminum flat tube having a plurality of heat medium flow passages therein and brazed to an outer surface of the combustion chamber main body. A heat exchanger characterized in that a galvanized layer is previously formed on surfaces of an aluminum combustion chamber main body and an aluminum flat tube, and the aluminum combustion chamber main body and the aluminum flat tube are brazed. Manufacturing method.