JP2015064159A - Heat exchanger and manufacturing method of heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce pressure loss and improve heat exchange efficiency by preventing a brazing material from flowing into the inside of a hairpin pipe.SOLUTION: In a heat exchanger, the inner peripheral surface of an end part 41 of a U-shaped pipe 40 is connected so as to be fitted to the outer peripheral surface of an end part 21 of a hairpin pipe 20, and by an auxiliary member 30 continuously covering the outer peripheral surface of the hairpin pipe 20 and the outer peripheral surface of the U-shaped pipe 40, the outer peripheral surface of the U-shaped pipe 40 and the outer peripheral surface of the hairpin pipe 20 are connected. Consequently, a brazing material is prevented from flowing into the inside of the hairpin pipe 20, and then reduction in heat exchange efficiency due to increase in pressure loss and brazing material jamming of the flow passage in the hairpin pipe 20 can be prevented.

Description

  The present invention relates to a heat exchanger, and more particularly to a cross fin tube heat exchanger used in an air conditioner or the like.

  A conventional cross fin tube type heat exchanger has a plurality of hairpin tubes penetrating through holes formed in a surface portion of a laminated fin in which plate-like fins are stacked at a predetermined interval, and U for connecting hairpin tubes to each other. The connection part of the said hairpin pipe | tube and the said U-shaped pipe is welded with the brazing material.

  As shown in FIG. 14, the connection portion between the hairpin tube and the U-shaped tube forms a large-diameter portion 121 by expanding the tube end portion of the hairpin tube 120 penetrating the laminated fin 110 and having the opening portion facing upward. Further, the end portion of the hairpin tube is expanded to form the expanded portion 122. A U-shaped tube 140 having an outer diameter slightly smaller than the inner diameter of the large diameter portion 121 is inserted into the large diameter portion 121. At this time, the brazing material 150 is disposed in the expanded portion 122 of the hairpin tube, and the inner peripheral surface of the large-diameter portion 121 and the outer peripheral surface of the U-shaped tube 140 are joined by the brazing material 150 by being placed in a furnace (for example, known For example, see Patent Document 1).

JP 2002-263879 A

  However, when the hairpin tube 120 and the U-shaped tube 130 are joined in this manner, the amount of use of the brazing material 150 by the welding operator and the subtle operation adjustment such as the heating temperature are affected, and the soldering will be as shown in FIG. The material 150 may protrude from the inner surface side of the hairpin tube 120 through the gap between the joint surfaces.

  The brazing material 150 that has entered the hairpin tube 120 becomes a flow path resistance in the tube, resulting in increased pressure loss and reduced heat exchange efficiency. In the worst case, the brazing material 150 may clog the inside of the hairpin tube 120.

  The present invention has been made to solve such a problem. By preventing the brazing material 150 from flowing into the hairpin tube 120 beyond the connection portion, the heat exchange efficiency due to an increase in pressure loss is achieved. It is an object of the present invention to provide a heat exchanger and a heat exchanger manufacturing method that prevent a decrease in the temperature and clogging of the brazing material in the hairpin tube 120.

  The heat exchanger of the present invention is a cross fin type having a plurality of laminated fins, a plurality of hairpin tubes inserted through through holes provided in the fins, and a connecting tube connecting different hairpin tubes. In the heat exchanger, the connection pipe is composed of a connection pipe end connected to the hairpin pipe, and a bent pipe continuous with the connection pipe end, and the connection pipe end has an inner peripheral surface of the connection pipe end. It is fitted so as to overlap with the outer peripheral surface of the tube end of the hairpin tube, and has an auxiliary member that continuously covers the outer peripheral surface of the hairpin tube and the outer peripheral surface of the connecting tube, on the inner peripheral surface of the auxiliary member, The outer peripheral surface of the connection tube and the outer peripheral surface of the hairpin tube are each joined by a brazing material.

  Further, the auxiliary member connects the small-diameter portion larger than the outer diameter of the hairpin tube, the large-diameter portion larger than the outer diameter of the connecting tube, the small-diameter portion and the large-diameter portion, and the small-diameter portion from the small-diameter portion side. And a tapered connection portion having a diameter that gradually increases toward the large-diameter portion side.

  In the heat exchanger manufacturing method of the present invention, a plurality of hairpin tubes are arranged at a predetermined interval, and the plurality of laminated fins are inserted into a plurality of through holes provided in the hairpin tubes. A step of assembling so as to be inserted, a step of expanding the plurality of hairpin tubes, joining the hairpin tubes and the fins, a small diameter portion having an inner diameter larger than an outer diameter of the hairpin tube, and one end of the small diameter portion A connecting portion having an inner diameter that gradually increases toward the other end, a large diameter portion having one end connected to the connecting portion, and one end connected to the large diameter portion toward the other end. The step of inserting an auxiliary member consisting of a tube-expanding portion whose inner diameter gradually increases from the small-diameter portion into the hairpin tube and a radial gap between the hairpin tube and the large-diameter portion differ in the hairpin tubes Connecting pipe to connect the pipe flow path A step of inserting a tube end, a ring-shaped brazing material is disposed in the expanded portion, and the connecting tube and the hairpin tube are brazed to the auxiliary member with the end of the hairpin tube facing upward And a process.

  According to the present invention, by connecting the hairpin tube and the connecting tube with the brazing material via the hairpin tube and the auxiliary member in contact with the outer peripheral surface of the connecting tube, the brazing material passes the connecting portion and the The hairpin tube is prevented from flowing into the hairpin tube, thereby preventing a decrease in heat exchange efficiency due to an increase in pressure loss and clogging of the brazing material in the hairpin tube.

It is a schematic perspective view which shows the whole heat exchanger of 1st Embodiment of this invention. It is a schematic perspective view which shows the components which comprise the heat exchanger of 1st Embodiment of this invention. It is a schematic sectional drawing which shows the hairpin tube and auxiliary member after joining with the fin set in the heat exchanger of 1st Embodiment of this invention. It is a schematic sectional drawing which shows the hairpin tube and U-shaped tube after fitting the auxiliary member in the heat exchanger of 1st Embodiment of this invention. It is a schematic sectional drawing which shows the hairpin tube and auxiliary member after insertion of the U-shaped tube in the heat exchanger of the first embodiment of the present invention. It is a schematic sectional drawing which shows the connection part of the hairpin pipe after welding and the U-shaped pipe in the heat exchanger of 1st Embodiment of this invention. It is a schematic sectional drawing which shows the other form of the U-shaped tube in the heat exchanger of 1st Embodiment of this invention. It is a schematic block diagram which shows the connection part of the hairpin pipe | tube and U-shaped pipe after welding in the heat exchanger of 2nd Embodiment of this invention. It is a schematic perspective view which shows the tube sheet in the heat exchanger of 3rd Embodiment of this invention. It is a schematic sectional drawing which shows the junction part of the hairpin tube and auxiliary | assistant tube plate in the heat exchanger of 3rd Embodiment of this invention. It is a schematic sectional drawing which shows after the welding process of the hairpin pipe | tube and the auxiliary | assistant tube sheet in the heat exchanger of 3rd Embodiment of this invention. It is a schematic sectional drawing which shows the connection part of the hairpin tube and U-shaped tube in the heat exchanger of 3rd Embodiment of this invention. It is a schematic sectional drawing which shows the after-welding process of the hairpin tube and U-shaped tube in the heat exchanger of 3rd Embodiment of this invention. It is sectional drawing which shows the connection part of the hairpin tube and U-shaped tube of the conventional heat exchanger.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments, and can be variously modified without departing from the gist of the present invention.

  FIG. 1 shows a heat exchanger 1 according to the present embodiment, which is a fluid such as a refrigerant flowing through an in-tube flow path formed by a hairpin tube 20 and a U-tube 40 described later, and air passing between laminated fins 11. FIG. 2 is a schematic perspective view of a cross fin tube type heat exchanger that performs heat exchange with a fluid such as FIG. 2, and FIG. 2 is an exploded perspective view of the heat exchanger 1.

  As shown in FIG. 2, the heat exchanger 1 of the present embodiment includes a fin set 10 including a laminated fin 11 in which fins 11 a are stacked and a pair of tube plates 12, a plurality of hairpin tubes 20, and a plurality of U-shapes. It is comprised from the pipe | tube 40, the some auxiliary member 30, and the ring brazing material 50 mentioned later.

  The fin 11a is a plate-like aluminum fin having a slit or the like formed on the surface thereof, and transfers heat of a fluid such as a refrigerant flowing through the hairpin tube 20. The laminated fins 11 are formed by overlapping a plurality of fins 11a in the vertical direction with a predetermined interval.

  The tube sheet 12 is a pair of metal plates that are provided on both sides in the stacking direction of the stacked fins 11 and have higher rigidity than the fins 11a. The tube plate 12 is provided with a fixing portion (not shown) for screw fixing when the heat exchanger 1 is attached to a product main body such as an air conditioner.

  Further, as described above, the fin set 10 is constituted by the laminated fins 11 and the pair of tube plates 12 provided on both sides in the laminating direction of the laminated fins 11.

  The laminated fin 11 and the tube plate 12 constituting the fin set 10 are provided with a through hole 13 provided to penetrate an end portion 21 of a hairpin tube 20 described later. The diameter of the through hole 13 is slightly larger than the outer diameter of the hairpin tube 20.

  The hairpin tube 20 is a metal tube having a groove shape or the like inside, and is bent into a U shape as shown in the figure. When the heat exchanger 1 is used, a fluid such as a refrigerant flows through the inside, and the hairpin tube 20 transfers the heat of the fluid to the fins 11a. The hairpin tube 20 is subjected to tube expansion after passing through the end 21 through the through holes 13 of the laminated fins 11 and the tube plate 12, and is brought into pressure contact with the fin assembly 10. Thereby, the fin set 10 and the hairpin tube 20 are joined.

  The U-shaped tube 40 is a metal tube and includes a bent tube portion 42 formed in a U shape and an end portion 41 that is a tube end. It is a connecting pipe that connects the end portions 21 of adjacent hairpin tubes 20 fixed to the fin set 10 and connects the in-tube flow paths of the hairpin tubes 20. The end 41 of the U-shaped tube 40 is expanded, and the inner diameter is slightly larger than the outer diameter of the hairpin tube 20 after the expansion. In the present embodiment, the U-shaped tube end portion 41 is expanded, but the inner diameter of the curved tube portion 42 is slightly larger than the outer diameter of the hairpin tube 20 after the expansion, as shown in FIG. If a product is used, it is not necessary to expand the tube, and the number of processing can be reduced. Moreover, although it is set as the U-shaped pipe | tube 40 which connects the edge parts 21 of the adjacent hairpin tube 20 fixed to the fin set 10 in a present Example, if the edge parts 21 of different hairpin tubes 20 are connected, it is. It may be a connecting pipe that connects the end portions 21 that are not adjacent to each other. More specifically, it may be a connecting tube that connects the hairpin tube 20a and the hairpin tube 20c or the hairpin tube 20d in FIG.

  The auxiliary member 30 is a cylindrical metal part, and as shown in FIG. 3, a small-diameter portion 31, a connection portion 33, a large-diameter portion 32, and a tube expansion portion 34 are formed in order, and the hairpin tube 20. And U-tube 40 are connected.

  The small-diameter portion 31 is a part of the auxiliary member 30 and has an inner diameter that is slightly larger than the outer diameter after the hairpin tube 20 is expanded.

  The large diameter portion 32 is a part of the auxiliary member 30 and has an inner diameter slightly larger than the outer diameter of the U-shaped tube end portion 41.

  The connecting portion 33 is a part of the auxiliary member 30 and is located between the small diameter portion 31 and the large diameter portion 32 and has a tapered surface whose inner diameter gradually decreases from the large diameter portion 32 side to the small diameter portion 31 side. Have.

  The expanded pipe portion 34 is a part of the auxiliary member 30, and has an inner diameter that is larger than that of the large diameter portion, and has a tapered shape in which the inner diameter increases from the large diameter portion 32 toward the end portion. The pipe expansion part 34 becomes an installation place of the ring brazing material 50 described later at the time of welding.

  As shown in FIG. 4, the ring brazing material 50 is a brazing material formed in a ring shape, and an alloy having a melting point lower than that of the hairpin tube 20, the U-shaped tube 40, and the auxiliary member 30 that are base materials is used.

  Next, the connection location of the hairpin tube 20 and the U-shaped tube 40 will be described in detail with reference to FIG.

  As shown in FIG. 6, the end 21 of the hairpin tube 20 penetrating the fin set 10 is inserted into the end 41 of the U-shaped tube 40. Further, there is a slight space between the outer peripheral surface of the hairpin tube 20 and the inner peripheral surface of the small-diameter portion 31 of the auxiliary member 30, and the ring brazing material 50 installed in the expanded tube portion 34 is melted into the space. It flows in and forms the joint part 51B. Further, there is a slight space between the outer peripheral surface of the end portion 41 of the U-shaped tube 40 and the inner peripheral surface of the large-diameter portion 32 of the auxiliary member 30, and the ring brazing material 50 installed in the expanded tube portion 34 is provided. It melt | dissolves and flows into the said space, and the junction part 51A is formed. With the above configuration, the fitting portion between the hairpin tube 20 and the U-shaped tube 40 is covered by the auxiliary member 30, and the auxiliary member 30 includes the small-diameter portion 31 and the hairpin tube 20, and the large-diameter portion. Since 32 and the U-shaped tube 40 are each welded by the brazing material, the in-pipe flow path of the hairpin tube 20 and the in-pipe flow path of the U-shaped tube 40 are connected in a state where airtightness is ensured.

  Next, the manufacturing process of the heat exchanger 1 of this embodiment is demonstrated in detail using FIG. 2 thru | or 6. FIG.

  As shown in FIG. 2, in the cross fin tube heat exchanger of the present invention, first, the hairpin tube 20 has a plurality of through holes 13 provided in the fin assembly 10 so that the end portion 21 faces upward. A plurality are arranged at an interval corresponding to the arrangement interval. The through hole 13 of the fin set 10 is made to penetrate from the upper side to the end portion 21 of the arranged hairpin tube 20. After penetration, each hairpin tube 20 and the fin set 10 are joined by expanding each hairpin tube 20.

  Next, as shown in FIG. 3, the auxiliary member 30 is fitted outside the end portion 21 of the hairpin tube 20 so that the small diameter portion 31 is on the lower side and the large diameter portion 32 is on the upper side. At this time, the outer diameter of the hairpin tube 20 is slightly smaller than the inner diameter of the small diameter portion 31 of the auxiliary member 30. Further, a gap is created between the large diameter portion 32 of the auxiliary member 30 and the end portion 21 of the hairpin tube 20 in which the U-shaped tube end portion 41 can be inserted in the radial direction.

  Next, as shown in FIG. 4, the ring brazing material 50 is fitted on the outside of the U-shaped tube 40, and the U-shaped gap is formed between the large-diameter portion 32 of the auxiliary member 30 and the end portion 21 of the hairpin tube 20 described above. Insert the end 41 of the tube 40. At this time, the inner diameter of the end 41 of the U-shaped tube 40 is slightly larger than the outer diameter of the hairpin tube 20, and the outer diameter of the U-shaped tube 40 is slightly smaller than the inner diameter of the large-diameter portion 32 of the auxiliary member 30. After the insertion, when the ring brazing material 50 that has been fitted to the outside of the U-shaped tube 40 in advance is installed in the expanded portion 34 of the auxiliary member 30, the state shown in FIG.

  5, the ring brazing material 50 is melted and flows between the U-shaped tube end portion 41 and the large diameter portion 32 by its own weight as shown in FIG. 6. Further, the ring brazing material 50 also flows between the hairpin tube 20 and the small diameter portion 31. As a result, the U-shaped tube end portion 41 and the large-diameter portion 32, and the hairpin tube 20 and the small-diameter portion 31 are welded to form joint portions 51A and 51B, respectively. Connected in a secured state. In this embodiment, the ring brazing material 50 is fitted on the outside of the U-shaped tube 40 in advance, and then the U-shaped tube end portion 41 is a gap between the large-diameter portion 32 of the auxiliary member 30 and the end portion 21 of the hairpin tube 20. After that, the ring brazing material 50 fitted to the outside of the U-shaped tube 40 is installed in the expanded portion 34 of the auxiliary member 30, but after the ring brazing material 50 is installed in the expanded portion 34. The U-shaped tube end portion 41 may be inserted into the gap between the large diameter portion 32 of the auxiliary member 30 and the end portion 21 of the hairpin tube 20.

  According to said structure, the location where the hairpin pipe | tube 20 and the U-shaped pipe | tube 40 fit is covered with the auxiliary member 30, Furthermore, the auxiliary member 30 has the small diameter part 31 with the hairpin pipe | tube 20, and large The diameter portions 32 are joined to the U-shaped tube 40, respectively. Therefore, the hairpin tube 20 and the U-shaped tube 40 are connected in a state where airtightness is ensured.

  As described above, the inner peripheral surface of the end portion 41 of the U-shaped tube 40 is connected so as to fit the outer peripheral surface of the end portion 21 of the hairpin tube 20, and the outer peripheral surface of the hairpin tube 20 and the U-shaped tube 40. Since the auxiliary member 30 that continuously covers the outer peripheral surface of the U-shaped tube 40 is joined to the outer peripheral surface of the U-shaped tube 40 and the outer peripheral surface of the hairpin tube 20, the brazing material may flow into the hairpin tube 20. Therefore, it is possible to prevent a decrease in heat exchange efficiency due to an increase in pressure loss and clogging of the brazing material in the flow path in the hairpin tube 20.

  In the present embodiment, the connection pipe connected to the hairpin tube 20 is the U-shaped tube 40, but this is not limited as long as it is a component that connects the flow path in the hairpin tube 20, for example, a three-way vent pipe or the like. The same effect as the invention can be exhibited.

  Next, the heat exchanger 1 according to the second embodiment using the present invention, and a configuration for determining the suitability of welding during the manufacturing process of the heat exchanger 1 will be described with reference to FIG. In addition, since the other structure is the same as 1st Embodiment except the point which processed the small diameter part 31 of the auxiliary member 30, and the tube sheet 12, detailed description other than the added structure is abbreviate | omitted.

  Conventionally, in welding by placing brazing using a ring brazing material as in the present invention, whether or not welding has been performed so that airtightness is sufficiently established has been determined by visual inspection of the connecting portion. More specifically, the determination was made based on whether or not the gap A in FIG. 14 is filled with the brazing material over the entire circumference.

  In Example 1, about the joining part 51A between the U-shaped tube 40 and the large diameter part 32 of the auxiliary member 30, the visual determination could be performed as usual. However, since the joint portion 51B between the hairpin tube 20 and the small-diameter portion 31 of the auxiliary member 30 is covered with the auxiliary member 30, it cannot be visually determined as in the past, and is reliable. There's a problem.

  Therefore, the heat exchanger 1 of this embodiment is provided with the predetermined notch 31a in the small diameter part 31 of the auxiliary member 30, as shown in FIG. According to this configuration, if the melted brazing material can properly form a joint between the hairpin tube 20 and the small diameter portion 31 of the auxiliary member 30, the brazing material can be confirmed visually from the notch 31a. It is possible to determine whether welding has been performed so that airtightness is sufficiently established, and reliability can be ensured.

  The shape of the notch 31a is not limited to this as long as the brazing material can be checked, and the shape of the notch 31b of FIG. 8B or the shape of FIG. The shape like the peephole 31c may be sufficient.

  Further, as shown in FIG. 8D, a protrusion 12 a is provided in the vicinity of the through hole of the tube plate 12 so that a small gap 31 of the auxiliary member 30 is not brought into contact with the flat surface of the tube plate 12 and a certain gap is formed. By forming, the same effect as the notch 31a etc. can be exhibited.

  Next, a configuration for reducing the number of parts and man-hours in manufacturing the heat exchanger 1 in the heat exchanger 1 according to the third embodiment using the present invention will be described with reference to FIG. In addition, since the other structure is the same as 1st Embodiment except the point which changed the tube sheet 12 and the auxiliary member 30, and a manufacturing process, detailed description other than the added structure is abbreviate | omitted.

  The heat exchanger 1 of the first embodiment uses the auxiliary member 30 when connecting the hairpin tube 20 and the U-shaped tube 40. Compared with the conventional heat exchanger as shown in FIG. 14, this has a concern that the number of parts increases and the man-hour increases accordingly.

  Therefore, the heat exchanger 1 of the present embodiment includes a tube plate 60 with an auxiliary, which is formed by integrating a plurality of auxiliary members 30 on one side of the tube plate 12 of the first embodiment. As shown in FIG. 9, the auxiliary tube plate 60 includes a connection auxiliary portion 61 having a function as an auxiliary member and a plate portion 62 having a function as a tube plate. As a result, the number of parts and the number of man-hours can be significantly reduced as compared with the first embodiment in which the plurality of auxiliary members 30 are attached one by one.

  Next, the connection location of the hairpin tube 20 and the U-shaped tube 40 in the present embodiment will be described in detail. FIG. 10 shows that each of the hairpin tubes 20 is expanded by penetrating through the through holes 13 of the fin set 10 having the auxiliary tube plate 60 on one side to the end portion 21 of the plurality of hairpin tubes 20 and expanding each hairpin tube 20. 20 shows a state where the fin set 10 and the fin set 10 are joined.

  At this time, the small-diameter portion 611 of the connection auxiliary portion 61 of the auxiliary tube plate 60 is in pressure contact with the hairpin tube 20 by the expansion of the hairpin tube 20, but it is necessary to weld in order to ensure airtightness. However, since there is no means for confirming whether or not the brazing has appropriately turned between the inner peripheral surface of the small diameter portion 611 and the outer peripheral surface of the hairpin tube 20, the hairpin tube is provided by the auxiliary tube plate 60 as in the present embodiment. When it is set as the structure which covers the connection location of 20 and the U-shaped pipe 40, it is preferable to divide welding into two processes. Hereinafter, the manufacturing process of the heat exchanger 1 in this embodiment is demonstrated in detail.

  10, as described above, the end portions 21 of the plurality of hairpin tubes 20 are penetrated from above through the through holes 13 of the fin set 10 provided with the auxiliary tube plate 60 on one side, and each hairpin tube 20 is expanded. Then, each hairpin tube 20 and the fin set 10 are joined, and further, the large-diameter portion 612 of the auxiliary connecting portion 61 of the auxiliary tube plate 60 (the large-diameter portion 32 of the auxiliary member 30 of the first embodiment). And a small-diameter ring brazing material 52 is disposed in the gap between the end portion 21 of the hairpin tube 20. If it puts into a furnace in this state (1st welding process), as shown in FIG. 11, the small diameter ring brazing material 52 will melt | dissolve and the auxiliary | assistant tube plate 60 and the hairpin tube 20 will be welded, and it will become the junction part 53, and joining. The parts are connected in a state where airtightness is ensured by the brazing material.

  Here, the determination of whether the airtightness by welding of the joint part 53 is sufficiently established can be visually confirmed from above. Specifically, the determination is made based on whether or not the joint portion 53 is filled with the brazing material over the entire circumference.

  Next, as shown in FIG. 12, the end portion 41 of the U-shaped tube 40 is inserted into the gap between the large-diameter portion 612 of the connection assisting portion 61 of the auxiliary tube plate 60 and the end portion 21 of the hairpin tube 20. At this time, the inner diameter of the end 41 of the U-shaped tube 40 is slightly larger than the outer diameter of the hairpin tube 20, and the outer diameter of the U-shaped tube 40 is slightly smaller than the inner diameter of the large-diameter portion 612 of the connection assisting portion 61. After the insertion, the ring brazing material 50 fitted in advance to the outside of the U-shaped tube 40 is placed in the furnace in the state where the ring brazing member 614 of the connection auxiliary portion 61 is installed (second welding step).

  The ring brazing material 50 is melted by being placed in the furnace as shown in FIG. 12, and flows between the U-shaped tube 40 and the large diameter portion 612 by its own weight. As a result, as shown in FIG. 13, the U-shaped tube 40 and the large-diameter portion 612 are welded to form a joint portion 54, and the joint portion 54 is connected in a state where airtightness is ensured by a brazing material.

  According to said structure, the location where the hairpin tube 20 and the U-shaped tube 40 fit is covered with the connection auxiliary part 61 of the tube plate 60 with an auxiliary | assistant, Furthermore, the connection auxiliary | assistant part 61 has the small diameter part 611. The hairpin tube 20 and the large diameter portion 612 are joined to the U-shaped tube 40, respectively. Therefore, the hairpin tube 20 and the U-shaped tube 40 are connected in a state where airtightness is ensured.

  Note that the small-diameter ring brazing material 52 melted in the first welding process may flow down during the second welding process, and the connection state between the auxiliary tube plate 60 and the hairpin tube 20 by the joint portion 53 may not be maintained. Therefore, a structure in which the melting point of the ring brazing material 50 is lower than the melting point of the small-diameter ring brazing material 52 may be used. By doing so, the temperature of the furnace in the second welding process is set lower than the temperature of the furnace in the first welding process without melting the joint 53 formed by the small-diameter ring brazing material 52 during the second welding process. The ring brazing material 50 can be melted to form the joint 54.

DESCRIPTION OF SYMBOLS 1 Heat exchanger 10 Fin set 11 Laminated fin 12 Tube plate 12a Protrusion part 13 Through-hole 20 Hairpin pipe 21 End part 30 Auxiliary member 40 U-shaped pipe 41 U-shaped pipe end part 50 Brazing filler metal 51A, B Joint part

Claims (3)

In a cross fin type heat exchanger having a plurality of laminated fins, a plurality of hairpin tubes inserted in through holes provided in the fins, and a connection tube connecting different hairpin tubes.
The connection pipe is composed of a connection pipe end connected to the hairpin pipe, and a bent pipe continuous with the connection pipe end.
The connecting pipe end is fitted so that the inner peripheral surface overlaps the outer peripheral surface of the tube end of the hairpin tube,
An auxiliary member that continuously covers the outer peripheral surface of the hairpin tube and the outer peripheral surface of the connection tube;
The heat exchanger characterized in that the outer peripheral surface of the connecting pipe and the outer peripheral surface of the hairpin tube are joined to the inner peripheral surface of the auxiliary member by a brazing material, respectively.   The auxiliary member connects a small diameter portion larger than the outer diameter of the hairpin tube, a large diameter portion larger than the outer diameter of the connection tube, the small diameter portion and the large diameter portion, and the large diameter from the small diameter portion side. The heat exchanger according to claim 1, further comprising: a tapered connection portion that gradually increases in diameter toward the portion side. Arranging a plurality of hairpin tubes at a predetermined interval, and assembling the plurality of laminated fins so that the hairpin tubes are inserted through a plurality of through holes provided in the fins;
Expanding the plurality of hairpin tubes, and joining the hairpin tubes and the fins;
A small-diameter portion having an inner diameter larger than the outer diameter of the hairpin tube, a connecting portion whose one end is connected to the small-diameter portion, and the inner diameter gradually increases toward the other end, and a large-diameter where one end is connected to the connecting portion. A step of inserting an auxiliary member composed of a portion and an expanded portion whose one end is connected to the large diameter portion and the inner diameter gradually increases toward the other end side, from the small diameter portion;
Inserting a pipe end of a connecting pipe that connects the different hairpin pipes into a radial gap between the hairpin pipe and the large diameter part; and
Disposing a ring-shaped brazing material in the tube expansion portion, and brazing the connection tube and the hairpin tube to the auxiliary member with an end of the hairpin tube facing upward. Method for manufacturing a heat exchanger.

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