JP2002174496A - Heat exchanger and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger that can be manufactured easily and can improve the brazing properties between a header and a tube. SOLUTION: The heat exchanger comprises a header 11 where a refrigerant is circulated, a tube insertion hole 12 that is provided at the header 11, and a flat tube 2 that is inserted into the tube insertion hole 12 and at the same time is joined to the header 11. In the heat exchanger, the sectional area of the tube insertion hole 12 increases from the inside to the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger used for an air conditioner or the like utilizing a CO ₂ refrigerant and a method for producing the same.

[0002]

2. Description of the Related Art A conventional flat tube heat exchanger is shown in FIGS.
It was shown to. In the figure, reference numeral 1 denotes a header in which a refrigerant flows. The header 1 is provided with a plurality of tube insertion holes 3 to which the flat tubes 2 are connected. In a state where the flat tube 2 is brazed to the tube insertion hole 3, fins 4 which are sandwiched between the flat tubes 2 and formed in a waveform are provided. A core 5 is formed by the flat tubes 2 and the fins 4. In order to braze the flat tube 2 into the tube insertion hole 3, first, the brazing material 6 is supplied to the outer surface of the header 1, the flat tube 2 is inserted into the tube insertion hole 3, and then the brazing material 6 is melted. Make the attachment.

In recent years, there has been an increasing interest in preserving the global environment. However, there is a concern that an alternative chlorofluorocarbon, such as R134a, which has been conventionally used as a refrigerant for air conditioners for vehicles, will have an effect on global warming. ing.
For this reason, research has been conducted on a vehicle air conditioner using a substance originally existing in the natural world, that is, a so-called natural refrigerant, as a substance replacing the alternative Freon refrigerant or the like. As a candidate for such a natural refrigerant, carbon dioxide (CO ₂ ) has attracted attention. This CO ₂ not only contributes significantly less to global warming than CFC alternatives, is not flammable, and is basically harmless to the human body. From such a background, a vapor compression refrigeration cycle using carbon dioxide (hereinafter abbreviated as a CO ₂ refrigeration cycle) has been proposed.

[0004]

In such a CO ₂ refrigeration cycle, the refrigerant pressure is higher than that of ordinary Freon. In comparison, the header 1 is configured to be thicker. For this reason, the tube insertion hole 3 is formed by machining. However, if the straight tube insertion hole 3 is formed by machining, the flat tube 2 and the insertion hole 3 cannot be inserted into the insertion hole 3 unless the flat tube 2 and the insertion hole 3 are accurately arranged to face each other in a straight line. However, there is a problem that the flat tube 2 is difficult to be inserted. Further, since the header 1 is thick, the molten brazing material 6 hardly flows to the inside of the header 1 at the time of brazing, and there is a problem that brazing failure occurs and the price is low. Furthermore, at the time of brazing heating, a temperature difference occurs in the heat exchanger due to a difference in heat capacity of the constituent members, and the central portion of the core tends to become high in temperature. For this reason, the molten brazing material 6 easily flows to the central portion of the core on the high-temperature side, and the fluidity of the molten brazing material 6 to the inside of the header is further deteriorated, so that the brazing property of the header tube is reduced, and There has been a problem that erosion by the brazing material 6 of the tube occurs, resulting in deterioration of quality.

The present invention has been made in view of the above circumstances, and has as its object to provide a heat exchanger that can be easily manufactured. It is another object of the present invention to provide a method for manufacturing a heat exchanger that can improve the brazing property between a header and a tube.

[0006]

According to the first aspect of the present invention, there is provided a header through which a refrigerant flows, a tube insertion hole provided in the header, and a tube inserted into the tube insertion hole and joined to the header. And a flat tube, wherein the tube insertion hole is formed to have a larger cross-sectional area from the inside to the outside.

In this heat exchanger, since the outer opening edge of the tube insertion hole is formed large, when the flat tube is inserted, the flat tube is guided by the opening edge and inserted into the tube insertion hole. It will be easier. As the shape, for example, a chamfer, a curved surface, a step, or the like can be adopted.

According to a second aspect of the present invention, there is provided a header through which a refrigerant flows, a tube insertion hole provided in the header, and a flat tube inserted into the tube insertion hole and joined to the header. In the method for manufacturing a heat exchanger, a brazing material is supplied to an inner wall surface of the header, and the flat tube is inserted into the tube insertion hole, and then brazing is performed.

In this method of manufacturing a heat exchanger, the brazing material supplied to the inner wall of the header easily flows to the center of the core due to the temperature gradient. That is, since the molten brazing material flows between the header and the flat tube to the outside of the header, brazing between the header and the flat tube is realized.
Further, by visually checking from the outside of the header whether or not the brazing material has flowed to the outside of the header, it can be confirmed that the header and the flat tube have been brazed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of an air conditioner according to the present invention will be described with reference to the drawings. Note that the same components as those in the related art are denoted by the same reference numerals, and description thereof is omitted. In FIG. 1A, reference numeral 11 denotes a header through which a refrigerant flows. The header 11 has a tube insertion hole 12 into which the flat tube 2 is inserted. Since the chamfered portion (C surface) 13 is formed at the outer opening edge of the tube insertion hole 12 as shown in the figure, the cross-sectional area of the tube insertion hole 12 increases from the inside to the outside. .

In the heat exchanger configured as described above, when the flat tube 2 is inserted into the tube insertion hole 12, the flat tube 2 is guided by the chamfered portion 13, so that the flat tube 2 can be easily inserted into the tube insertion hole 12. Can be inserted.

The brazing is performed as follows. The brazing material 15 is supplied to the inner wall of the header 11, and the flat tube 2 is inserted into the tube insertion hole 12. Then, the brazing material 15 is melted. The molten brazing material 15 easily flows to the center of the core 5 due to the temperature gradient. That is, as shown in FIG.
Therefore, the header 11 and the flat tube 2 are brazed because they flow between the flat tube 2 and the outside of the header 11. Thus, by supplying the brazing material 15 to the inner surface of the header 11 instead of the outer surface, the brazing property between the header 11 and the flat tube 2 can be improved. Further, by visually observing whether or not the brazing material 15 flows to the outside of the header, it can be confirmed that the header 15 and the flat tube 2 are brazed.

As a modification, as shown in FIG. 2 (a), the outer opening edge of the tube insertion hole 2 is formed into a curved surface (R surface) 1.
It may be eight. Further, as shown in FIG. 2B, at least one step 19 may be provided so that the cross-sectional area of the tube insertion hole 12 increases from the inside to the outside. Also in these cases, the flat tube 2 can be easily inserted into the tube insertion hole 12 similarly to the above.

Further, as shown in FIG. 3, the header 21 is divided into an outer member 21a and an inner member 21b. Fig. 3 (a)
As shown in the figure, these outer member 21a and inner member 21b
The opening area of the tube insertion hole 12 may be made different from the above, or the inner wall of the tube insertion hole 12 may be inclined as shown in FIG. You may do it.

The refrigerant flow path provided in the header is not limited to a circular shape in a sectional view, but may be a square with an R with a rounded corner,
It may be an octagon, a regular octagon, or the like.

[0016]

According to the present invention described above, the following effects can be obtained. According to the first aspect of the present invention, since the outer opening edge of the tube insertion hole is formed large, when the flat tube is inserted, the flat tube is guided by the opening edge and inserted into the tube insertion hole. Easier to do. Therefore, manufacturing becomes easy.

According to the second aspect of the present invention, since the molten brazing material flows between the header and the flat tube to the outside of the header, the brazing property between the header and the flat tube can be improved. Further, by visually observing whether or not the brazing material has flowed to the outside of the header, it can be confirmed that the header and the flat tube have been brazed.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a heat exchanger shown as a first embodiment of the present invention.

FIG. 2 is a partial sectional view of a heat exchanger shown as a modification of the present invention.

FIG. 3 is a partial sectional view of a heat exchanger shown as a modification of the present invention.

FIG. 4 is a perspective view showing the overall configuration of a flat tube heat exchanger.

FIG. 5 is a perspective view of a header used in the heat exchanger.

6A and 6B are cross-sectional views showing a joint state between the header and the flat tube, wherein FIG. 6A is a cross-sectional view along AA in FIG. 5, and FIG.
FIG. 3A is a cross-sectional view along the line BB in FIG.

[Explanation of symbols]

 2 Flat tube 11 Header 12 Tube insertion hole 13 Chamfered part 15 Brazing material 18 Curved surface 19 Step

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shigeo Sakai 1F, Takamichi, Iwazuka-cho, Nakamura-ku, Nagoya-shi, Aichi F-term in Nagoya Research Laboratory, Mitsubishi Heavy Industries, Ltd. 3L065 BA11 CA17 3L103 AA01 AA05 BB42 CC30 DD08 DD32 DD34 DD42

Claims (2)

[Claims] 1. A heat exchanger comprising a header through which a refrigerant flows, a tube insertion hole provided in the header, and a flat tube inserted into the tube insertion hole and joined to the header. A heat exchanger characterized in that the tube insertion hole has a larger cross-sectional area from the inside to the outside. 2. A method for manufacturing a heat exchanger comprising a header through which a refrigerant flows, a tube insertion hole provided in the header, and a flat tube inserted into the tube insertion hole and joined to the header. 5. The method for manufacturing a heat exchanger according to claim 1, wherein a brazing material is supplied to an inner wall surface of the header, and the flat tube is inserted into the tube insertion hole and then brazed.