WO2020213023A1

WO2020213023A1 - Heat exchanger and air conditioner

Info

Publication number: WO2020213023A1
Application number: PCT/JP2019/016103
Authority: WO
Inventors: 達郎永山; 智嗣上山; 満貞早川
Original assignee: 三菱電機株式会社
Priority date: 2019-04-15
Filing date: 2019-04-15
Publication date: 2020-10-22
Also published as: JPWO2020213023A1; JP7086278B2

Abstract

The present invention provides a heat exchanger, comprising: a heat transfer tube that channels a refrigerant; a header in which an insertion hole, into which an end part of the heat transfer tube is inserted, is formed, the header channeling the refrigerant flowing into the heat transfer tube and/or the refrigerant flowing out of the heat transfer tube; and a fin attached to the outer periphery part of the heat transfer tube, the heat transfer tube and the header being joined by brazing, and the heat transfer tube and the fin being joined by brazing, wherein the heat transfer tube has at least one groove formed at a position between the header and the fin, the groove extending from the header towards the fin.

Description

Heat exchanger and air conditioner

The present invention relates to a heat exchanger having improved corrosion resistance and an air conditioner in which the heat exchanger is used.

The heat exchanger is used, for example, as an outdoor heat exchanger and an indoor heat exchanger of an air conditioner. Since the outdoor heat exchanger is used outdoors, moisture adheres to it. Indoor heat exchangers are used indoors, but when they function as evaporators, condensation causes moisture to adhere to them. When moisture adheres to the heat exchanger and the heat exchanger made of a metal material corrodes, the heat exchange performance deteriorates due to refrigerant leakage. For this reason, heat exchangers are often provided with anticorrosion measures. As an anticorrosion measure, for example, a material having a lower redox potential than the heat transfer tube is provided on the surface of the heat transfer tube of the heat exchanger. Further, for example, as an anticorrosion measure, a material having a lower redox potential than the heat transfer tube is used as the material that comes into contact with the heat transfer tube of the heat exchanger. Hereinafter, a material having a lower redox potential than the heat transfer tube will be simply referred to as a material having a lower redox potential.

The heat transfer tube and the parts that come into contact with the heat transfer tube are joined by brazing. The parts that come into contact with the heat transfer tube are, for example, headers and fins. At the time of brazing, the wax material that melts and becomes liquid flows on the surface of the heat transfer tube and spreads. At this time, when a part having contact with the heat transfer tube is formed by a material having a base redox potential, the material having a base redox potential is contained in the melted brazing material and is contained in the heat transfer tube. It diffuses to the surface. Further, the brazing material may include a material having a low redox potential as a material constituting the brazing material. The material having a low redox potential constituting the brazing material is also contained in the melted brazing material and diffuses to the surface of the heat transfer tube. A material having a low redox potential diffused on the surface of a heat transfer tube during brazing has an effect of preventing corrosion of the heat transfer tube.

When there are irregularities or deposits on the surface of the heat transfer tube, there may be places where the melted wax material easily flows and places where the melted wax material does not easily flow on the surface of the heat transfer tube. In such a case, on the surface of the heat transfer tube, many materials having a low redox potential are diffused in places where the brazing material easily flows, and many materials having a low redox potential are diffused in places where the brazing material is difficult to flow. It will not be in a state. As a result, on the surface of the heat transfer tube, a dark portion of the material having a low redox potential and a thin portion of the material having a low redox potential are formed. That is, uneven distribution of materials having a low redox potential occurs on the surface of the heat transfer tube. In such a case, the dark portion of the material having a low redox potential is likely to be corroded, which may eventually reduce the corrosion resistance of the heat transfer tube.

As a method for solving such a problem, it is conceivable to adopt the configuration described in Patent Document 1 for the heat transfer tube. The heat exchanger described in Patent Document 1 includes a heat transfer tube which is a flat tube, and a header brazed to the heat transfer tube. Specifically, an insertion hole into which a heat transfer tube is inserted is formed on the side surface of the header. Further, a heat transfer tube is inserted into the insertion hole, and the heat transfer tube and the header are brazed and joined at the periphery of the insertion hole. A groove extending in a direction substantially perpendicular to the insertion direction of the heat transfer tube into the insertion hole is formed on the surface of the heat transfer tube. In the heat exchanger described in Patent Document 1, when the brazing material melted during brazing flows on the surface of the heat transfer tube, the brazing material that has flowed to the groove stays in the groove. As a result, the heat exchanger described in Patent Document 1 controls the place where the brazing material stays.

Japanese Unexamined Patent Publication No. 2016-217587

The heat exchanger described in Patent Document 1 cannot control the flow of the melted brazing material in the range from the brazed portion to the groove between the heat transfer tube and the header during brazing. Therefore, in the heat exchanger described in Patent Document 1, in the range from the brazed portion to the groove between the heat transfer tube and the header, the redox potential is still low and the redox potential is low. The thin part of the material is formed. Therefore, the conventional heat exchanger has a problem that uneven distribution of materials having a low redox potential cannot be suppressed on the surface of the heat transfer tube.

The present invention has been made to solve the above-mentioned problems, and obtains a heat exchanger capable of suppressing uneven distribution of a material having a low redox potential generated on the surface of a heat transfer tube during brazing. That is the first purpose. A second object of the present invention is to obtain an air conditioner provided with such a heat exchanger.

The heat exchanger according to the present invention has a heat transfer tube through which a refrigerant flows, and an insertion hole into which an end of the heat transfer tube is inserted is formed, and the heat exchanger flows into the heat transfer tube and flows out of the heat transfer tube. A header through which at least one flows and fins attached to the outer peripheral portion of the heat transfer tube are provided, the heat transfer tube and the header are joined by brazing, and the heat transfer tube and the fin are joined by brazing. In the heat exchanger, the heat transfer tube is formed with at least one groove extending from the header toward the fin at a position between the header and the fin.

Further, the air conditioner according to the present invention includes a refrigeration cycle circuit having a compressor, an outdoor heat exchanger, an expansion valve and an indoor heat exchanger, and at least one of the outdoor heat exchanger and the indoor heat exchanger. The heat exchanger according to the present invention is used.

The heat exchanger according to the present invention can control the flow of the melted brazing material on the surface of the heat transfer tube by the groove formed in the heat transfer tube during brazing. Therefore, the heat exchanger according to the present invention can suppress uneven distribution of the material having a low redox potential generated on the surface of the heat transfer tube during brazing as compared with the conventional case.

It is a figure which shows the air conditioner which concerns on Embodiment 1. FIG. It is a front view which shows the outdoor heat exchanger which concerns on Embodiment 1. FIG. FIG. 5 is a vertical cross-sectional view showing the vicinity of a joint between a header and a heat transfer tube in the outdoor heat exchanger according to the first embodiment. FIG. 5 is an exploded perspective view showing the vicinity of a joint between a header and a heat transfer tube in the outdoor heat exchanger according to the first embodiment. It is a perspective view which shows another example of the heat transfer tube of the outdoor heat exchanger which concerns on Embodiment 1. FIG. It is a figure which shows the vicinity of the insertion hole of the header of the outdoor heat exchanger which concerns on Embodiment 2. FIG. It is a figure which shows the vicinity of the insertion hole of the header of the outdoor heat exchanger which concerns on Embodiment 3. FIG.

In each of the following embodiments, an example of a heat exchanger and an example of an air conditioner will be described with reference to the drawings.

Embodiment 1.
FIG. 1 is a diagram showing an air conditioner according to the first embodiment.
The air conditioner 1 includes a refrigeration cycle circuit 10 in which a refrigerant circulates. Further, the refrigeration cycle circuit 10 includes a compressor 11, a four-way valve 12, an outdoor heat exchanger 20, an expansion valve 13, and an indoor heat exchanger 14. That is, the compressor 11, the four-way valve 12, the outdoor heat exchanger 20, the expansion valve 13, and the indoor heat exchanger 14 are connected by a refrigerant pipe to form a refrigeration cycle circuit 10. These components of the refrigeration cycle circuit 10 are housed in the outdoor unit 2 or the indoor unit 3. In the first embodiment, the outdoor unit 2 houses a compressor 11, a four-way valve 12, an outdoor heat exchanger 20, and an expansion valve 13. An indoor heat exchanger 14 is housed in the indoor unit 3.

The basic operation of the air conditioner 1 will be explained. First, in the case of heating operation, the gaseous refrigerant compressed by the compressor 11 flows into the indoor heat exchanger 14 through the four-way valve 12. The gaseous refrigerant that has flowed into the indoor heat exchanger 14 is condensed from the gaseous state to a liquid state by exchanging heat with the air around the indoor heat exchanger 14, and the ambient air is exchanged by the heat exchange at that time. It will warm up. The refrigerant that has become liquid in the indoor heat exchanger 14 is expanded by the expansion valve 13 to become a gas-liquid two-phase state, and flows into the outdoor heat exchanger 20. The gas-liquid two-phase refrigerant that has flowed into the outdoor heat exchanger 20 evaporates by exchanging heat with the air around the outdoor heat exchanger 20 to become a gas state, and the ambient air is exchanged by the heat exchange at that time. It will be cooled. The refrigerant that has become gaseous in the outdoor heat exchanger 20 is sucked into the compressor 11 and compressed.

In the case of cooling operation, the flow of refrigerant is reversed from that in the case of heating operation by switching the four-way valve 12. Specifically, the gaseous refrigerant compressed by the compressor 11 flows into the outdoor heat exchanger 20 through the four-way valve 12. The gaseous refrigerant that has flowed into the outdoor heat exchanger 20 is condensed from the gaseous state to a liquid state by exchanging heat with the air around the outdoor heat exchanger 20, and the ambient air is removed by the heat exchange tube at that time. It will warm up. The refrigerant that has become liquid in the outdoor heat exchanger 20 is expanded by the expansion valve 13 to become a gas-liquid two-phase state, and flows into the indoor heat exchanger 14. The gas-liquid two-phase refrigerant that has flowed into the indoor heat exchanger 14 evaporates by exchanging heat with the air around the indoor heat exchanger 14 to become a gas state, and the ambient air is exchanged by the heat exchange at that time. It will be cooled. The refrigerant that has become gaseous in the indoor heat exchanger 14 is sucked into the compressor 11 and compressed.

If the air conditioner 1 is a dedicated cooling machine or a dedicated heating machine, it is not necessary to provide the four-way valve 12. The compression method and operation method of the compressor 11 are not particularly limited, but for example, an inverter compressor whose capacity can be controlled can be used as the compressor 11.

Next, the outdoor heat exchanger 20 will be described in more detail.
FIG. 2 is a front view showing the outdoor heat exchanger according to the first embodiment. FIG. 3 is a vertical cross-sectional view showing the vicinity of the joint between the header and the heat transfer tube in the outdoor heat exchanger according to the first embodiment. FIG. 4 is an exploded perspective view showing the vicinity of the joint between the header and the heat transfer tube in the outdoor heat exchanger according to the first embodiment.

The outdoor heat exchanger 20 includes a heat transfer tube 30, a header 40, and fins 50. The heat transfer tube 30, the header 40, and the fins 50 are made of metal.

In the first embodiment, a flat tube is used as the heat transfer tube 30. Specifically, the outer peripheral portion of the heat transfer tube 30 which is a flat tube includes a flat surface portion 31, a flat surface portion 32 parallel to the flat surface portion 31, and a pair of end portions 33 connecting the flat surface portion 31 and the flat surface portion. .. A plurality of refrigerant flow paths 34 through which the refrigerant flows are formed in the heat transfer tube 30 which is a flat tube. Further, in the first embodiment, the outdoor heat exchanger 20 is installed so that the heat transfer tube 30 extends in the horizontal direction. Further, in the first embodiment, a plurality of heat transfer tubes 30 are provided. These plurality of heat transfer tubes 30 are arranged at predetermined intervals in the vertical direction. The end portion of each heat transfer tube 30 in the tube axial direction is inserted into an insertion hole 41 formed in a side surface portion of the header 40, as will be described later.

In the following, when explaining the directions of each configuration of the outdoor heat exchanger 20, the insertion direction X, the first direction Y, and the second direction Z may be used for explanation. The insertion direction X is the direction in which the heat transfer tube 30 is inserted into the insertion hole 41 of the header 40. In the first embodiment, the insertion direction X is the horizontal direction. The first direction Y is perpendicular to the insertion direction X and parallel to the flat surface portion 31 of the heat transfer tube 30. In the first embodiment, the first direction Y is a horizontal direction perpendicular to the insertion direction X. The second direction Z is perpendicular to the insertion direction X and perpendicular to the first direction Y. In the first embodiment, the second direction Z is the vertical direction.

The header 40 has, for example, a cylindrical shape. In the header 40, at least one of the refrigerant flowing into the heat transfer tube 30 and the refrigerant flowing out of the heat transfer tube 30 flows. An insertion hole 41 into which the end portion of the heat transfer tube 30 is inserted is formed in the side surface portion of the header 40. As described above, in the first embodiment, a plurality of heat transfer tubes 30 are arranged in the vertical direction at a predetermined interval. For this reason, a plurality of insertion holes 41 are also formed on the side surface portion of the header 40 at predetermined intervals in the vertical direction. The header 40 and the heat transfer tube 30 are brazed and joined to the peripheral edge of the insertion hole 41 and the outer peripheral portion of the heat transfer tube 30 in a state where the end portion of the heat transfer tube 30 is inserted into the insertion hole 41 of the header 40. As described above, the outdoor heat exchanger 20 according to the first embodiment includes a pair of headers 40. In the following, when it is desired to distinguish between these headers 40, one header 40 will be referred to as a header 40a and the other header 40 will be referred to as a header 40b.

The header 40a is provided with a pipe 42 and a pipe 43. The refrigerant pipe 15 shown in FIG. 1 is connected to the pipe 42. The refrigerant pipe 15 is a refrigerant pipe that connects the four-way valve 12 and the outdoor heat exchanger 20. Further, the refrigerant pipe 16 shown in FIG. 1 is connected to the pipe 43. The refrigerant pipe 16 is a refrigerant pipe that connects the expansion valve 13 and the outdoor heat exchanger 20. Therefore, the inside of the header 40a according to the first embodiment is partitioned into a flow path communicating with the refrigerant pipe 15 and a flow path communicating with the refrigerant pipe 16.

Then, in the outdoor heat exchanger 20 according to the first embodiment, the refrigerant flowing into the header 40a from one of the

refrigerant pipes

15 and 16 flows through a part of the plurality of heat transfer pipes 30. After that, it flows into the header 40b. The refrigerant that has flowed into the header 40b flows through the remaining part of the plurality of heat transfer tubes 30, then passes through the header 40a, and flows out to the other of the

refrigerant pipes

15 and 16. That is, the outdoor heat exchanger 20 according to the first embodiment is a parallel flow type heat exchanger.

In the first embodiment, a corrugated fin is used as the fin 50. The fins 50 are arranged between the heat transfer tubes 30 adjacent to each other in the vertical direction, and are attached to the outer peripheral portions of the heat transfer tubes 30. The fin 50 and the heat transfer tube 30 are brazed and joined at a position where the fin 50 and the heat transfer tube 30 face each other. For example, the end of the fin 50 is bent to form a brazed portion 51 facing the heat transfer tube 30. At the end of the fin 50, the heat transfer tube 30 and the brazed portion 51 are brazed and joined.

If a hole is formed in the heat transfer tube 30 or the header 40 due to corrosion, the refrigerant leaks from the hole and the heat exchange performance of the outdoor heat exchanger 20 deteriorates. Here, in general, many heat transfer tubes are provided in the outdoor heat exchanger. Further, in general, the heat transfer tube is thinner than the header because it exchanges heat between the refrigerant and the surrounding air. Therefore, in order to suppress the deterioration of the heat exchange performance of the outdoor heat exchanger 20, it is important to suppress the corrosion of the heat transfer tube 30. Therefore, in the first embodiment, the corrosion of the heat transfer tube 30 is suppressed as follows.

As the material of the header 40 and the fin 50 that come into contact with the heat transfer tube 30, a material having a lower redox potential than that of the heat transfer tube 30 is used. Hereinafter, a material having a lower redox potential than the heat transfer tube 30 may be simply referred to as a material having a lower redox potential. Since the header 40 and the fin 50 are materials having a low redox potential, they corrode preferentially over the heat transfer tube 30. As a result, corrosion of the heat transfer tube 30 is suppressed.

However, in order for this anticorrosion method to work, the form of water droplets adhering to the heat transfer tube 30 is limited. Specifically, it is necessary that the water droplets adhere to the heat transfer tube 30 in a state where the water droplets are in contact with the heat transfer tube 30 and the header 40, or in a state where the water droplets are in contact with the heat transfer tube 30 and the fins 50. If water droplets adhere to the heat transfer tube 30 only in contact with the heat transfer tube 30, this anticorrosion method does not work and the corrosion of the heat transfer tube 30 cannot be suppressed. Here, as described above, in the first embodiment, a flat tube is used as the heat transfer tube 30. Therefore, water droplets tend to stay on the flat surface portion 31, and water droplets tend to adhere to the heat transfer tube 30 only in contact with the water droplets.

Therefore, in the outdoor heat exchanger 20 according to the first embodiment, the surface of the heat transfer tube 30 is covered with a material having a low redox potential to further suppress the corrosion of the heat transfer tube 30. The surface of the heat transfer tube 30 is covered with a material having a low redox potential when the heat transfer tube 30, the header 40, and the fins 50 are joined by brazing.

Specifically, at the time of brazing, the brazing material that melts and becomes liquid flows on the surface of the heat transfer tube 30 and spreads. At this time, the material having a low redox potential forming the header 40 and the fin 50 is contained in the melted brazing material and diffuses to the surface of the heat transfer tube 30. Further, the brazing material may include a material having a low redox potential as a material constituting the brazing material. A material having a low redox potential constituting the brazing material is also contained in the melted brazing material and diffuses to the surface of the heat transfer tube 30. As a result, the surface of the heat transfer tube 30 is covered with a material having a low redox potential.

In this anticorrosion method, if a material having a low redox potential uniformly covers the surface of the heat transfer tube 30, corrosion of the heat transfer tube 30 is suppressed without being affected by the form of water droplets adhering to the heat transfer tube 30. it can. The installation environment of the outdoor unit 2 in which the outdoor heat exchanger 20 is housed varies, and it is difficult to control the form of water droplets adhering to the outdoor heat exchanger 20 after the outdoor unit 2 is installed. Therefore, the anticorrosion method in which the material having a low redox potential covers the surface of the heat transfer tube 30 is an effective method for anticorrosion of the heat transfer tube 30.

However, when the surface of the heat transfer tube 30 has irregularities or deposits, the surface of the heat transfer tube 30 may have a place where the melted wax material easily flows and a place where the melted wax material does not easily flow. In such a case, on the surface of the heat transfer tube 30, many materials having a low redox potential are diffused in places where the brazing material easily flows, and many materials having a low redox potential are diffused in places where the brazing material does not easily flow. It will not spread. As a result, on the surface of the heat transfer tube 30, a dark portion of the material having a low redox potential and a thin portion of the material having a low redox potential are formed. That is, uneven distribution of the material having a low redox potential occurs on the surface of the heat transfer tube 30. In such a case, the dark portion of the material having a low redox potential is likely to be corroded, which may eventually reduce the corrosion resistance of the heat transfer tube 30.

Therefore, in the outdoor heat exchanger 20 according to the first embodiment, at least one groove 35 extending from the header 40 toward the fin 50 is provided in the heat transfer tube 30 at a position between the header 40 and the fin 50. Is formed. Specifically, in the first embodiment, at least one groove 35 is formed in the flat surface portion 31 of the heat transfer tube 30. Further, in the first embodiment, two grooves 35 are formed in the flat surface portion 31 of the heat transfer tube 30. Since at least one groove 35 extending from the header 40 toward the fin 50 is formed in the heat transfer tube 30, the brazing material melted at the time of brazing flows along the groove 35. As a result, the flow of the brazing material on the surface of the heat transfer tube 30 can be controlled, and uneven distribution of the material having a low redox potential generated on the surface of the heat transfer tube 30 can be suppressed as compared with the conventional case. Therefore, corrosion of the heat transfer tube 30 can be suppressed, and the corrosion resistance of the outdoor heat exchanger 20 can be improved.

In the first embodiment, two grooves 35 are formed in the heat transfer tube 30, but the number of grooves 35 is not limited to two. For example, one groove 35 may be formed in the heat transfer tube 30. By flowing the brazing material melted at the time of brazing along the groove 35, the flow of the brazing material on the surface of the heat transfer tube 30 can be controlled, and the redox potential generated on the surface of the heat transfer tube 30 is low. Uneven distribution of materials can be suppressed more than before. However, if the brazing material is excessively accumulated in the groove 35, the brazing material and the material for forming the heat transfer tube 30 are mixed, so that the melting point of the material for forming the heat transfer tube 30 is lowered, and a hole is formed at the place where the melting point is lowered. There is also the possibility that it will end up. Therefore, it is preferable that the number of grooves 35 formed in the heat transfer tube 30 is a plurality.

Further, when forming a plurality of grooves 35 in the heat transfer tube 30, three or more grooves 35 may be formed. The larger the number of grooves 35, the more evenly the wax material melted on the surface of the heat transfer tube 30 can flow. That is, when the number of grooves 35 is large, the material having a low redox potential can be evenly diffused on the surface of the heat transfer tube 30, and the distribution unevenness of the material having a low redox potential generated on the surface of the heat transfer tube 30. Can be further suppressed.

Further, when a plurality of grooves 35 are formed in the flat surface portion 31 of the heat transfer tube 30, it is preferable to arrange these grooves 35 as shown in FIG.

FIG. 5 is a perspective view showing another example of the heat transfer tube of the outdoor heat exchanger according to the first embodiment.
The heat transfer tube 30 of the outdoor heat exchanger 20 shown in FIG. 5 has a plurality of grooves 35 formed in the flat surface portion 31. These plurality of grooves 35 are arranged at intervals in the first direction Y. Here, in the flat surface portion 31, the range including the central position in the first direction Y is defined as the first range 38. Further, in the flat surface portion 31, the range that is closer to the end portion 33 than the first range 38 in the first direction Y is defined as the second range 39. In this case, the grooves 35 are densely arranged in the first range 38 as compared with the second range 39.

When a flat tube is used as the heat transfer tube 30, the brazing material melted during brazing is likely to be supplied to the flat portion constituting the outer peripheral portion of the flat tube. That is, in the flat surface portion 31 shown in FIG. 5, the brazing material melted in the first range 38 is more likely to be supplied than in the second range 39. Therefore, by arranging the plurality of grooves 35 as shown in FIG. 5, the brazing material in the first range 38 of the flat surface portion 31 to which a large amount of the brazing material is supplied can be easily flowed along the grooves 35. Therefore, when a flat tube is used as the heat transfer tube 30, by arranging a plurality of grooves 35 as shown in FIG. 5, it is possible to further suppress uneven distribution of materials having a low redox potential generated on the surface of the heat transfer tube 30. ..

Further, in the first embodiment, the groove 35 is formed only in the flat surface portion 31 of the heat transfer tube 30, but the groove 35 may be formed in the flat surface portion 32 or the groove 35 is formed in the end portion 33. You may. Since the melted wax material flows through the groove 35, many materials have a low redox potential. Therefore, if there is a portion on the surface of the heat transfer tube 30 where corrosion is likely to occur, it is possible to provide a groove 35 in the portion to improve the corrosion resistance of the portion.

Further, in the first embodiment, the cross-sectional shape of the groove 35 is not particularly mentioned, but the cross-sectional shape of the groove 35 is not particularly limited. The cross-sectional shape referred to here is a cross-sectional shape when the groove 35 is cut in a cross section perpendicular to the direction in which the groove 35 extends. For example, the cross-sectional shape of the groove 35 may be a semicircular shape, a triangular shape, a quadrangular shape, or a polygonal shape of a pentagon or more. Further, there may be a protrusion inside the groove 35, or a groove may be further formed inside the groove 35. Further, in the first embodiment, the groove 35 extends parallel to the insertion direction X, but the extending direction of the groove 35 does not have to be parallel to the insertion direction X. The groove 35 may extend from the header 40 toward the fin 50 and may be inclined with respect to the insertion direction X.

It is preferable that the cross-sectional area of the groove 35 satisfies the following conditions. The cross-sectional area of the groove 35 is the area of the cross-sectional shape when the groove 35 is cut in a cross section perpendicular to the direction in which the groove 35 extends. When there are a plurality of grooves 35, the cross-sectional area of the grooves 35 shall indicate the average of the cross-sectional areas of each groove 35. Here, the volume of the brazing material required for brazing the peripheral edge of the insertion hole 41 and the outer peripheral portion of the heat transfer tube 30 is defined as V1. The volume of the brazing material supplied for brazing the peripheral edge of the insertion hole 41 and the outer peripheral portion of the heat transfer tube 30 is defined as V2. Let N be the number of grooves 35 formed in the heat transfer tube 30. Let L be the average length of the grooves 35 formed in the heat transfer tube 30. When defined in this way, the cross-sectional area of the groove 35 is preferably smaller than (V2-V1) / NL. By defining the cross-sectional area of the groove 35 in this way, it is possible to prevent a shortage of brazing material and poor joining when brazing the peripheral edge of the insertion hole 41 and the outer peripheral portion of the heat transfer tube 30. When the cross-sectional shape of the groove 35 is square, if each side of the cross section is made smaller than the square root of (V2-V1) / NL, the cross-sectional area of the groove 35 becomes smaller than (V2-V1) / NL. ..

Further, the position of the end portion 36 of the groove 35 on the header 40 side is not limited to the position shown in FIG. Specifically, as shown in FIG. 3, the end portion 36 of the groove 35 on the header 40 side is arranged at a position facing the peripheral wall of the insertion hole 41 of the header 40. In other words, the groove 35 extends to a position facing the peripheral wall of the insertion hole 41. However, when the peripheral edge of the insertion hole 41 and the outer peripheral portion of the heat transfer tube 30 are brazed and joined, if the brazing material can flow into the groove 35, the end portion 36 on the header 40 side of the groove 35 will be the outer periphery of the header 40. It may be arranged on the fin 50 side with respect to the surface. However, if the groove 35 extends to a position facing the peripheral wall of the insertion hole 41, the brazing material can easily flow into the groove 35. That is, when the groove 35 extends to a position facing the peripheral wall of the insertion hole 41, it is easier to suppress uneven distribution of the material having a low redox potential generated on the surface of the heat transfer tube 30. Therefore, it is preferable that at least one groove 35 extends to a position facing the peripheral wall of the insertion hole 41.

Further, the position of the end portion 37 on the fin 50 side of the groove 35 is not limited to the position shown in FIG. Specifically, as shown in FIG. 3, the end portion 37 of the groove 35 on the fin 50 side is arranged at a position facing the brazed portion 51 of the fin 50. In other words, the groove 35 extends to a position facing the fin 50. However, when the fin 50 and the outer peripheral portion of the heat transfer tube 30 are brazed and joined, if the brazing material can flow into the groove 35, the end portion 37 on the fin 50 side of the groove 35 is closer to the header 40 than the fin 50. It may be arranged in. However, if the groove 35 extends to a position facing the fin 50, the brazing material can easily flow into the groove 35. That is, when the groove 35 extends to a position facing the fin 50, it is easier to suppress uneven distribution of the material having a low redox potential generated on the surface of the heat transfer tube 30. Therefore, it is preferable that at least one groove 35 extends to a position facing the fin 50.

Further, in the first embodiment, a flat tube is used as the heat transfer tube 30, but the heat transfer tube 30 is not limited to the flat tube. For example, various heat transfer tubes such as a circular heat transfer tube, an elliptical heat transfer tube, a polygonal heat transfer tube, and an uneven heat transfer tube can be used as the heat transfer tube 30.

Further, although the cylindrical header 40 is used in the first embodiment, the header 40 is not limited to such a configuration. For example, the header 40 may have a rectangular parallelepiped shape. Further, for example, a laminated header in which plate-shaped members are laminated to form a flow path inside may be used as the header 40.

Further, the fin 50 is not limited to the above configuration. For example, the fin 50 does not have to be provided with the brazing portion 51. The points where the fins 50 and the heat transfer tube 30 face each other may be brazed and joined. For example, when the fin 50 is a corrugated fin, the folded-back portion is a portion facing the heat transfer tube 30. Therefore, the fin 50 and the heat transfer tube 30 may be brazed and joined at the folded portion. Further, for example, a plate-shaped fin into which the heat transfer tube 30 is inserted into the opening may be used as the fin 50.

Further, in the first embodiment, the specific materials of the heat transfer tube 30, the header 40, the fins 50, and the brazing material are not particularly limited. As specific materials for the heat transfer tube 30, the header 40, the fins 50, and the brazing material, for example, the following materials can be used. For example, aluminum or an aluminum alloy can be used as the material of the heat transfer tube 30. In this case, when the header 40 and the fin 50 are formed of a material having a lower oxidation-reduction potential than the heat transfer tube 30, for example, the material having a lower oxidation-reduction potential is made of pure aluminum as the material of the header 40 and the fin 50. The added aluminum alloy, zinc, zinc alloy, magnesium, magnesium alloy, lithium, lithium alloy, silicon, and a material obtained by adding a material other than silicon to silicon can be used. As the material of the header 40 and the fin 50, a material in which these materials are combined may be used. Further, as the brazing material, for example, an aluminum alloy containing silicon can be used. As the brazing material, a material other than an aluminum alloy containing silicon, which has a lower redox potential than the heat transfer tube 30, may be used. Further, at least one of the heat transfer tube 30, the header 40 and the fin 50 may be formed of a clad material having a brazing material on its surface. Further, as the heat transfer tube 30, a heat transfer tube using aluminum or an aluminum alloy as a base material and having a material having a lower redox potential than the base material on the surface of the base material may be used. Such a heat transfer tube 30 can be obtained, for example, by spraying a material having a lower redox potential than the base material on the surface of the base material. Further, for example, such a heat transfer tube 30 can be formed of a clad material in which a material having a lower redox potential than the base material is provided on the surface of the base material. When such a heat transfer tube 30 is used, the material having a lower redox potential than the heat transfer tube 30 is a material having a lower redox potential than the base material.

Further, in the first embodiment, the outdoor heat exchanger 20 in which the heat transfer tube 30 is provided in the horizontal direction is illustrated, but the configuration of the outdoor heat exchanger 20 is not limited to the configuration. For example, the outdoor heat exchanger 20 may be configured such that the heat transfer tube 30 is vertically provided. Further, for example, the outdoor heat exchanger 20 may have a configuration in which the heat transfer tubes 30 are provided at different angles. Further, for example, in the first embodiment, the outdoor heat exchanger 20 is a parallel flow type heat exchanger, but the outdoor heat exchanger 20 is a heat exchanger in which a refrigerant flows in series through each of the heat transfer tubes 30. There may be.

Further, in the first embodiment, the groove 35 is formed in the heat transfer tube 30 of the outdoor heat exchanger 20, but the indoor heat exchanger 14 may have the same configuration as the outdoor heat exchanger 20. The corrosion resistance of the indoor heat exchanger 14 can be improved.

As described above, in the heat exchanger according to the first embodiment, the heat transfer tube 30 through which the refrigerant flows and the insertion hole 41 into which the end of the heat transfer tube 30 is inserted are formed, and the refrigerant and the heat transfer tube 30 flowing into the heat transfer tube 30 are formed. It includes a header 40 through which at least one of the refrigerants flowing out of the heat transfer tube 30 flows, and fins 50 attached to the outer peripheral portion of the heat transfer tube 30. Further, in the heat exchanger according to the first embodiment, the heat transfer tube 30 and the header 40 are joined by brazing, and the heat transfer tube 30 and the fins 50 are joined by brazing. Then, at least one groove 35 extending from the header 40 toward the fin 50 is formed in the heat transfer tube 30 at a position between the header 40 and the fin 50.

In the heat exchanger according to the first embodiment, the flow of the melted brazing material on the surface of the heat transfer tube 30 can be controlled by the groove 35 formed in the heat transfer tube 30 at the time of brazing. Therefore, the heat exchanger according to the first embodiment can suppress uneven distribution of the material having a low redox potential generated on the surface of the heat transfer tube 30 during brazing as compared with the conventional case.

Embodiment 2.
When a flat tube is used as the heat transfer tube 30, the insertion hole 41 of the header 40 may be formed in the following shape, for example. In the second embodiment, items not particularly described will be the same as those in the first embodiment, and the same functions and configurations as those in the first embodiment will be described using the same reference numerals.

FIG. 6 is a diagram showing the vicinity of the insertion hole of the header of the outdoor heat exchanger according to the second embodiment. FIG. 6 is a view of the insertion hole 41 of the header 40 observed in the insertion direction X.
In the header 40 according to the second embodiment, when the opening width W of the insertion hole 41 in the second direction Z is viewed in the first direction Y, it becomes wider from the end toward the center. Therefore, in the outdoor heat exchanger 20 according to the second embodiment, when the flat heat transfer tube 30 and the insertion hole 41 are viewed in the first direction Y, they are inserted into the outer peripheral portion of the heat transfer tube 30. The distance between the hole 41 and the peripheral wall increases from the end to the center. Therefore, when brazing and joining the peripheral edge of the insertion hole 41 and the heat transfer tube 30, the wax used near the center of the heat transfer tube 30 in the first direction Y as compared with the vicinity of the end of the heat transfer tube 30 on the first direction Y side. The amount of material increases.

For example, when a cylindrical header 40 is used, the distance between the header 40 and the fin 50 becomes smaller toward the center position in the first direction Y. In such a case, if a flat tube is used as the heat transfer tube 30, a large amount of brazed material melted during brazing is likely to be supplied to the vicinity of the center of the heat transfer tube 30 in the first direction Y. That is, a material having a low redox potential tends to diffuse near the center of the heat transfer tube 30 in the first direction Y. However, by forming the insertion hole 41 as in the second embodiment, the amount of brazing material required for brazing the vicinity of the center of the first direction Y of the heat transfer tube 30 and the peripheral edge of the insertion hole 41 increases. Therefore, it is possible to prevent the melted brazing material from flowing near the center of the heat transfer tube 30 in the first direction Y. That is, it is possible to suppress the diffusion of a material having a low redox potential near the center of the heat transfer tube 30 in the first direction Y.

Therefore, even when a flat tube is used as the heat transfer tube 30 under the condition that the brazing material melted at the time of brazing is easily supplied to the vicinity of the center of the first direction Y of the heat transfer tube 30, the present embodiment 2 By forming the insertion hole 41 as described above, uneven distribution of the material having a low redox potential generated on the surface of the heat transfer tube 30 can be suppressed. That is, even when a flat tube is used as the heat transfer tube 30 under the condition that the brazing material melted at the time of brazing is easily supplied to the vicinity of the center of the first direction Y of the heat transfer tube 30, as in the second embodiment. By forming the insertion hole 41 in the heat transfer tube 30, corrosion of the heat transfer tube 30 can be suppressed, and the corrosion resistance of the outdoor heat exchanger 20 can be improved.

Here, by forming the insertion hole 41 as in the second embodiment, the amount of diffusion of the material having a low redox potential to the outer peripheral portion of the heat transfer tube 30 is insufficient, and the corrosion resistance of the heat transfer tube 30 is lowered. You might think that. However, when the uneven distribution of the material having a low redox potential is remarkable on the surface of the heat transfer tube 30, there is a high possibility that corrosion will occur locally in the dark portion of the material having a low redox potential. In addition, once local corrosion occurs, the site often continues to corrode. Therefore, when the uneven distribution of the material having a low redox potential tends to be remarkable on the surface of the heat transfer tube 30, the amount of diffusion of the material having a low redox potential to the outer periphery of the heat transfer tube 30 is carried out. By suppressing the heat transfer tube 30 as in Form 2, the corrosion resistance of the outdoor heat exchanger 20 can be improved.

Further, there is a possibility that the melting point of the material forming the heat transfer tube 30 decreases in a place where a large amount of material having a low redox potential accumulates, and a hole is formed in the place where the melting point decreases. From the viewpoint of suppressing this local dissolution, the configuration of suppressing the diffusion amount of the material having a low redox potential to the outer peripheral portion of the heat transfer tube 30 as in the second embodiment is effective.

The shape of the insertion hole 41 shown in FIG. 6 is an example. The shape of the insertion hole 41 is arbitrary as long as the opening width W becomes wider from the end toward the center when viewed in the first direction Y. For example, in the insertion hole 41 shown in FIG. 6, the opening width W is constant near the center of the first direction Y. However, the size of the opening width W may be different even near the center of the first direction Y. Further, in the insertion hole 41 shown in FIG. 6, the opening width W of the end portion in the first direction Y is not zero, but the opening width W of the end portion in the first direction Y may be zero. Further, although the outer peripheral edge of the insertion hole 41 shown in FIG. 6 is configured by combining straight lines, at least a part of the outer peripheral edge of the insertion hole 41 may be curved.

Embodiment 3.
When a flat tube is used as the heat transfer tube 30, the insertion hole 41 of the header 40 may be formed in the following shape, for example. In the third embodiment, items not particularly described are the same as those of the first embodiment or the second embodiment, and the same reference numerals are used for the same functions and configurations as those of the first embodiment or the second embodiment. Will be described.

FIG. 7 is a diagram showing the vicinity of the insertion hole of the header of the outdoor heat exchanger according to the third embodiment. FIG. 7 is a view of the insertion hole 41 of the header 40 observed in the insertion direction X.
In the header 40 according to the third embodiment, when the opening width W of the insertion hole 41 in the second direction Z is viewed in the first direction Y, it becomes wider from the center toward the end. Therefore, in the outdoor heat exchanger 20 according to the third embodiment, when the flat heat transfer tube 30 and the insertion hole 41 are viewed in the first direction Y, they are inserted into the outer peripheral portion of the heat transfer tube 30. The distance between the hole 41 and the peripheral wall increases from the center to the end. Therefore, when brazing and joining the peripheral edge of the insertion hole 41 and the heat transfer tube 30, the wax used near the end of the heat transfer tube 30 in the first direction Y as compared with the vicinity of the center of the heat transfer tube 30 on the first direction Y side. The amount of material increases.

For example, when a rectangular header 40 in which the distance between the header 40 and the fin 50 does not change in the first direction is used, the distance between the header 40 and the fin 50 is from the center position in the first direction to the end side. When a flat tube is used as the heat transfer tube 30, a large amount of the brazing material melted at the time of brazing is supplied to the vicinity of the end portion of the heat transfer tube 30 in the first direction Y, for example, when the header 40 that becomes smaller toward the direction of Easy to be done. That is, the material having a low redox potential tends to diffuse near the end of the heat transfer tube 30 in the first direction Y. However, by forming the insertion hole 41 as in the third embodiment, the amount of brazing material required for brazing the vicinity of the end of the heat transfer tube 30 in the first direction Y and the peripheral edge of the insertion hole 41 is large. Therefore, it is possible to prevent the melted brazing material from flowing near the end of the heat transfer tube 30 in the first direction Y. That is, it is possible to suppress the diffusion of a material having a low redox potential near the end of the heat transfer tube 30 in the first direction Y.

Therefore, even when a flat tube is used as the heat transfer tube 30 under the condition that the brazing material melted at the time of brazing is easily supplied to the vicinity of the end portion of the heat transfer tube 30 in the first direction Y, the third embodiment By forming the insertion hole 41 as described above, uneven distribution of the material having a low redox potential generated on the surface of the heat transfer tube 30 can be suppressed. That is, even when a flat tube is used as the heat transfer tube 30 under the condition that the brazing material melted at the time of brazing is easily supplied to the vicinity of the end portion of the heat transfer tube 30 in the first direction Y, the present embodiment 3 By forming the insertion hole 41 as described above, corrosion of the heat transfer tube 30 can be suppressed, and the corrosion resistance of the outdoor heat exchanger 20 can be improved.

The shape of the insertion hole 41 shown in FIG. 7 is an example. The shape of the insertion hole 41 is arbitrary as long as the opening width W becomes wider from the center toward the end when viewed in the first direction Y. For example, in the insertion hole 41 shown in FIG. 7, the opening width W is constant near the center of the first direction Y. However, the size of the opening width W may be different even near the center of the first direction Y. Further, although the outer peripheral edge of the insertion hole 41 shown in FIG. 6 is configured by combining straight lines, at least a part of the outer peripheral edge of the insertion hole 41 may be curved.

1 air conditioner, 2 outdoor unit, 3 indoor unit, 10 refrigeration cycle circuit, 11 compressor, 12 four-way valve, 13 expansion valve, 14 indoor heat exchanger, 15 refrigerant piping, 16 refrigerant piping, 20 outdoor heat exchanger, 30 heat transfer pipe, 31 flat part, 32 flat part, 33 end part, 34 refrigerant flow path, 35 groove, 36 end part, 37 end part, 38 first range, 39 second range, 40 header, 40a header, 40b header , 41 insertion hole, 42 piping, 43 piping, 50 fins, 51 brazing part, X insertion direction, Y 1st direction, Z 2nd direction.

Claims

The heat transfer tube through which the refrigerant flows and
An insertion hole into which the end of the heat transfer tube is inserted is formed, and a header through which at least one of the refrigerant flowing into the heat transfer tube and the refrigerant flowing out of the heat transfer tube flows.
The fins attached to the outer peripheral portion of the heat transfer tube and
With
A heat exchanger in which the heat transfer tube and the header are joined by brazing, and the heat transfer tube and the fins are joined by brazing.
A heat exchanger in which at least one groove extending from the header toward the fin is formed in the heat transfer tube at a position between the header and the fin.
The heat exchanger according to claim 1, wherein at least one of the grooves extends to a position facing the peripheral wall of the insertion hole.
The heat exchanger according to claim 1 or 2, wherein the at least one groove extends to a position facing the fin.
The heat exchanger according to any one of claims 1 to 3, wherein a plurality of the grooves are formed in the heat transfer tube.
The heat exchanger according to any one of claims 1 to 4, wherein the heat transfer tube is a flat tube having a flat surface portion on which at least one of the grooves is formed on the outer peripheral portion.
A plurality of the grooves are formed in the flat surface portion.
When the direction perpendicular to the insertion direction of the heat transfer tube into the insertion hole and parallel to the flat surface portion is set as the first direction.
The plurality of grooves are arranged at intervals in the first direction.
When looking at the plurality of grooves in the first direction,
In the first range including the central position in the first direction on the flat surface portion, the grooves are densely arranged as compared with the second range which is on the end side of the first range in the first direction. The heat exchanger according to claim 5.
The first direction is the direction perpendicular to the insertion direction of the heat transfer tube into the insertion hole and parallel to the flat surface portion.
When the direction perpendicular to the insertion direction of the heat transfer tube into the insertion hole and the direction perpendicular to the first direction is the second direction,
The heat exchanger according to claim 5 or 6, wherein when the opening width of the insertion hole in the second direction is viewed in the first direction, the width becomes wider from the end toward the center.
The first direction is the direction perpendicular to the insertion direction of the heat transfer tube into the insertion hole and parallel to the flat surface portion.
When the direction perpendicular to the insertion direction of the heat transfer tube into the insertion hole and the direction perpendicular to the first direction is the second direction,
The heat exchanger according to claim 5 or 6, wherein when the opening width of the insertion hole in the second direction is viewed in the first direction, the width becomes wider from the center toward the end.
Equipped with a refrigeration cycle circuit with a compressor, outdoor heat exchanger, expansion valve and indoor heat exchanger,
An air conditioner in which the heat exchanger according to any one of claims 1 to 8 is used in at least one of the outdoor heat exchanger and the indoor heat exchanger.