JP2013024511A - Heat exchanger, method of manufacturing heat exchanger, and refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger etc., which can be improved in heat transfer performance by increasing the area of contact of a fin collar with a heat transfer tube without causing the fin collar to crack.SOLUTION: The heat exchanger includes heat transfer tubes 1 which have a curved sectional shape, and plate-like fins 2 having insertion holes 4 formed in conformity with the shape of the heat transfer tubes 1. The fins 2 each have fin collars 6 raised along edges of the insertion holes 4, and brought into contact with curved parts of the heat transfer tubes 1 while being divided into a plurality of pieces by cuts 8.

Description

  The present invention relates to a heat exchanger configured by joining fins to a heat transfer tube for exchanging heat between a refrigerant and a fluid such as a gas, a manufacturing method thereof, and the like. In particular, the present invention relates to a heat exchanger using a heat transfer tube having a curved cross-sectional shape such as a flat shape.

  For example, a conventional flat tube heat exchanger in which the cross section of the heat transfer tube has a flat shape (flat shape) includes a plurality of flat heat transfer tubes arranged in parallel at regular intervals, and a heat transfer tube in the longitudinal direction of the plate surface. The same number and the same interval of insertion holes are provided, and a plurality of plate-like fins inserted into the heat transfer tubes and arranged at a constant interval are provided. The edge of the insertion hole provided in the fin is provided with a fin collar raised in the press process, and the heat transfer tube and the fin are joined by a brazing material or the like in the fin collar (for example, Patent Document 1). reference).

Japanese Patent Laying-Open No. 2003-214791 (page 14, FIG. 25)

  Here, the flat heat transfer tube has a curved side portion, and its cross-sectional shape has a curve. In conventional flat tube heat exchangers, fins with insertion holes are inserted into flat heat transfer tubes, so the fin collar provided at the edge of the fin insertion hole is a straight portion (hereinafter referred to as fin color straight line). Part) and a music part (hereinafter referred to as a fin collar music part) are mixed.

  For example, in the pressing process, the fin collar straight portion is raised by bending, whereas the fin collar bent portion is raised by burring. For this reason, tensile stress is not applied in the direction of the fold line in the fin collar linear part, whereas tensile stress is applied in the circumferential direction in the fin collar curved part, and the fin collar curved part rises while being plastically deformed in the circumferential direction. . Therefore, when the height of the fin collar curved portion is increased, there is a problem that the tensile stress at the tip of the fin collar curved portion increases, and the possibility that a crack starts from the tip of the fin collar curved portion increases.

  For example, in the case of a flat heat transfer tube, a plurality of holes are arranged in the major axis direction of the flat cross section, a rectangular hole adjacent to the fin collar straight portion, and a D-shaped hole adjacent to the fin collar curved portion And. In the flat tube heat exchanger, the area where one D-shaped hole can exchange heat with the fin collar bend is about 1.5 times the area where one rectangular hole can exchange heat with the fin collar straight part. For this reason, the fin collar curved portion greatly contributes to the heat transfer performance of the flat tube heat exchanger as compared with the fin collar linear portion.

  However, in the conventional flat tube heat exchanger, the height of the fin collar curved portion is as small as about 0.5 times the height of the fin collar straight portion so as not to cause cracks in the fin collar curved portion. It was designed as follows. For this reason, the contact area of the fin collar curved portion with respect to the heat transfer tube is limited, and the heat transfer performance cannot be improved more than the flat tube heat exchanger without causing a crack in the fin collar curved portion. As described above, it is difficult to increase the contact area of the curved portion of the fin collar formed corresponding to the heat transfer tube having the curved portion while maintaining the reliability of the heat exchanger, and the heat transfer performance is reduced. It was difficult to improve.

  The present invention has been made to solve the above problems, and can increase the contact area of the fin collar with respect to the heat transfer tube without causing cracks in the fin collar, thereby improving the heat transfer performance. The purpose is to obtain a heat exchanger or the like.

  The heat exchanger in the present invention includes a heat transfer tube having a curved cross-sectional shape and a plate-like fin having an insertion hole formed in accordance with the shape of the heat transfer tube, and the fin extends along the edge of the insertion hole. The curved portion of the rising and heat transfer tube has a fin collar which is divided into a plurality of pieces by a notch and brought into contact with each other.

  In the heat exchanger of the present invention, the notch is provided in the fin collar so that it is divided into a plurality of pieces and brought into contact with the heat transfer tube. While preventing, the height of the fin collar can be increased. And the contact area of a fin collar and a heat exchanger tube can be enlarged, and the effect that heat transfer performance can be improved is acquired.

It is a fragmentary perspective view of the flat tube heat exchanger in Embodiment 1 of this invention. It is a partial front view of the fin in Embodiment 1 of this invention. It is a figure which shows the correlation of notch angle (phi) and the tensile stress P. FIG. It is a figure which shows the correlation of the contact area S and the external heat transfer coefficient (alpha) ₀ . It is a figure which shows before starting of the fin collar 6 in Embodiment 2 of this invention. It is a figure which shows before starting of the fin collar 6 in Embodiment 3 of this invention. It is a figure which shows an example of the manufacturing process of the heat exchanger in Embodiment 4 of this invention. It is a figure which shows the cross section of the vicinity of the fin collar 6 in Embodiment 4 of this invention. It is a figure which shows the structure of the refrigerating-cycle apparatus in Embodiment 5 of this invention.

Embodiment 1 FIG.
FIG. 1 is a partial perspective view of a flat tube heat exchanger 20 according to Embodiment 1 of the present invention. In this embodiment, as a heat exchanger, a flat tube heat exchanger having a flat heat transfer tube whose part of the cross-sectional shape is a curve will be described. In FIG. 1, the flat tube heat exchanger 20 of Embodiment 1 has a plurality of flat heat transfer tubes 1 whose cross section is a straight line with a long side portion and whose short side portion is a curve such as a semicircular shape. The plurality of heat transfer tubes 1 are arranged in parallel with a certain interval in a direction orthogonal to the flow direction of the refrigerant flowing in the tubes. Moreover, it has a plurality of flat plate (rectangular) fins 2. The fins 2 are arranged in parallel at regular intervals in the refrigerant flow direction (direction orthogonal to the direction in which the heat transfer tubes 1 are arranged). Here, since the fin 2 of the present embodiment has a rectangular shape in which the arrangement direction of the heat transfer tubes 1 is longer than the length of the heat transfer tubes 1 in the width direction, the width direction of the heat transfer tubes 1 is the short direction, The arrangement direction of the heat transfer tubes 1 is defined as the longitudinal direction.

  A plurality of holes 3 are provided side by side in the width direction in the heat transfer tube 1, and a coolant for exchanging heat with, for example, air passing through the flat tube heat exchanger 20 flows in the holes 3. The fin 2 has a plurality of insertion holes 4 in the longitudinal direction. In order to correspond to each heat exchanger tube 1, each insertion hole 4 is provided with the same number as heat exchanger tube 1, and the same interval (except for both ends), for example. Further, a slit 5 formed by cutting and raising a part of the fin 2 is provided between the insertion holes 4. A fin collar 6 raised in a direction perpendicular to the fin 2 is provided at the edge of each insertion hole 4. And each heat-transfer tube 1 and each fin 2 are being fixed by joining the heat-transfer tube 1 and the fin collar 6 with a brazing material etc. Here, the heat transfer tube 1 according to the present embodiment has a shape in which the circular tube is flattened in two directions, and thus has a flat portion (a cross-sectional shape is a straight line) and a curved surface portion (a cross-sectional shape is a curve). For this reason, the fin collar 6 includes a fin collar straight portion 6 a that is in contact with the flat surface portion of the heat transfer tube 1 and a fin collar curved portion 6 b that is in contact with the curved surface portion of the heat transfer tube 1.

  FIG. 2 is a partial front view of the fin 2 in the first embodiment. FIG. 2A is a front view of a part of the fin 2 before the fin collar 6 is raised in the pressing process. FIG. 2B shows a partial front view when the fin 2 shown in FIG. 2A is pressed and the fin collar 6 is raised. FIG. 2C is a cross-sectional view taken along the line A-A ′ and the line B-B ′ of FIG.

  As shown in FIG. 2 (a), in the fin 2 before the pressing process, the flat pilot hole 7 in which the straight part and the curved part are continuous, and the center of the curved part of the pilot hole 7 as a starting point, radially. A notch 8 is provided by notching the fin collar bend 6b. For example, if the notches 8 are provided radially every 45 °, the fin collar curved portion 6b is divided into four pieces. The boundary line 9 is a line that becomes an edge of the insertion hole 4 after the fin collar 6 is formed and serves as a boundary (folded portion) between the fin 2 body and the fin collar 6. Here, in this embodiment, the notches 8 are provided every 45 ° and divided into four pieces, but the angle and the number of divisions are not limited thereto. For example, it may be divided into three parts every 60 °. Further, in order to prevent an excessive force from being applied to a part of the terminal portion of the notch 8 on the edge side of the insertion hole 4, the shape of the terminal portion may be semicircular so that the force is equally applied.

  Next, a procedure for creating the fins 2 will be described. 2B serves as a fulcrum, and the fin collar straight portion 6a and the fin collar curved portion 6b are raised to form the insertion hole 4. As shown in FIG. At this time, as shown in FIG. 2C, the fin collar straight line portion 6 a and the fin collar curved portion 6 b are raised vertically with respect to the fin 2. As shown in FIG. 2A, since the width from the boundary line 9 to the pilot hole 7 is the same in the straight portion and the curved portion, the height of the fin collar curved portion 6b is the fin collar straight portion 6a. It will be possible to secure the same height.

  FIG. 3 is a diagram showing the correlation between the angle φ formed by the adjacent notches 8 and the tensile stress (P) applied in the circumferential direction of the fin collar curved portion 6b. Here, since the fin collar of the conventional heat exchanger is not provided with the notch 8, φ = 180 °. Tensile stress P is applied to each of the plurality of raised fin collar curved portions 6b in the circumferential direction. From FIG. 3, compared to the semicircular fin collar bent portion as in the conventional flat tube heat exchanger, the notch 8 is provided and the fan-shaped divided fin collar bent portion 6 b is formed in the circumferential direction. It can be seen that the tensile stress P applied to is reduced.

  As described above, according to the flat tube heat exchanger 20 of the first embodiment, since the radial cutouts 8 are provided in the fin collar curved portion 6b, burring processing is performed as in the conventional flat tube heat exchanger. Therefore, the tensile stress applied in the circumferential direction of the fin collar curved portion 6b can be reduced as compared with the case where the fin collar curved portion is raised. For this reason, generation | occurrence | production of the crack in the fin collar curved part 6b can be prevented, increasing the contact area of the fin collar curved part 6b and the heat exchanger tube 1. FIG.

FIG. 4 shows the correlation between the contact area S of the conventional flat tube heat exchanger and the fin collar curved portion of Embodiment 1, and the external heat transfer coefficient α _o . As shown in FIG. 4, for example, compared to the contact area (about 4.09 mm ² ) of the fin collar curved portion of the conventional fin with the heat transfer tube 1 of the fin collar curved portion 6 b of the present embodiment. The contact area is twice or more (about 9.30 mm ² ). Accordingly, the heat transfer coefficient outside the tube is increased from 101.49 [W / (m ² · K)] to 101.76 [W / (m ² · K)], for example. Thus, the contact area between the heat transfer tube 1 and the fin collar curved portion 6b is made higher than that of the conventional flat tube heat exchanger by making the height of the fin collar curved portion 6b equal to the height of the fin collar linear portion 6a. The heat transfer performance can be improved as a whole flat tube heat exchanger.

Embodiment 2. FIG.
FIG. 5 is a partial front view of the fin 2 before the fin collar 6 is raised in the second embodiment of the present invention. In the fin 2 shown in the second embodiment, a circular pierce hole 10 is additionally provided at the terminal portion of the notch 8 with respect to the notch 8 described in the first embodiment. The diameter (D) of the pierced hole 10 is set to have a relationship of not less than the width (W) of the notch in the short axis direction (D ≧ W).

  As described above, in the flat tube heat exchanger 20 according to the second embodiment, the pierce hole 10 is provided at the end portion of the notch 8 on the edge side of the insertion hole 4, thereby forming a corner at the end portion of the notch 8. Even when the fin 2 is inserted into the insertion hole 4 with an excessive force in the heat transfer tube 1, the tensile stress applied in the circumferential direction of the terminal portion of the notch 8 is applied to the circumference of the pierce hole 10. Since it is dispersed in the direction, it is possible to prevent the occurrence of cracks starting from the terminal portion of the notch 8.

Embodiment 3 FIG.
FIG. 6 is a partial front view of the fin 2 before the fin collar 6 is raised in the third embodiment of the present invention. As shown in FIG. 6A, the fin 2 according to the third embodiment is provided with a notch 8 in which the radial notch described in the first embodiment is extended in the circumferential direction. At this time, as shown in FIG. 6B, for example, the terminal portion of the notch 8 is formed in a semicircular shape having the same diameter as the notch width. In some cases, as shown in FIG. 6B, a pierce hole 11 may be provided at the end of the notch 8.

  As described above, in the flat tube heat exchanger 20 according to the third embodiment, the notch 8 is extended in the circumferential direction along the spots of the insertion hole 4, and thus formed at the end portion of the notch 8. Thus, for example, the tensile stress applied in the circumferential direction when the fin collar 6 is started up can be reduced. At this time, since the right-angled portion is eliminated from the terminal portion of the notch 8 by making the terminal portion semicircular, forming the piercing hole 11, etc., excessive force is applied to the insertion hole 4 of the fin 2. Even when the heat transfer tube 1 is inserted, the tensile stress applied in the circumferential direction of the end portion of the notch 8 can be dispersed, and cracks starting from the end portion of the notch 8 can be prevented. Can do.

Embodiment 4 FIG.
FIG. 7 is a diagram illustrating an example of a manufacturing process of the flat tube heat exchanger 20 according to Embodiment 4 of the present invention. In the fourth embodiment, a procedure for manufacturing a flat tube heat exchanger will be described with reference to FIG. First, a flat pilot hole 7 is formed by pressing a coiled fin material (S1). Further, the slit 5 is cut and raised by pressing (S2). Further, a notch 8 is formed in the fin collar bend 6b (S3). Then, the fin collar 6 is started up by press working (S4). Here, the rising angle θ is set to an acute angle (especially 45 ° <θ <90 °). Then, the fin 2 is inserted while raising the fin collar 6 vertically using the force inserted into the heat transfer tube 1 (S5), and the fin collar 6 of the fin 2 and the heat transfer tube 1 are joined with a brazing material or the like ( S6). The flat tube heat exchanger 20 is manufactured as described above.

  FIG. 8 is a cross-sectional view of the vicinity of the fin collar 6 of the flat tube heat exchanger 20 according to Embodiment 4 of the present invention. FIG. 8A shows a cross-sectional view of the vicinity of the fin collar 6 when the fin collar 6 is raised at an acute angle by press working in S4 described above. FIG. 8B is a sectional view of the vicinity of the fin collar 6 when the fin 2 is inserted into the heat transfer tube 1 in S6 described above. When the fin 2 is inserted in a state where the fin collar 6 is raised by setting the rising angle θ to an acute angle as shown in FIG. 8A, the spring back is brought into the fin collar 6 as shown in FIG. 8B. The force 18 is applied. For this reason, the fin collar 6 can be brought into close contact with the heat transfer tube 1.

  As described above, in the fourth embodiment, when the flat tube heat exchanger 20 is manufactured, the fin collar 6 is raised to an acute angle (particularly θ: 45 ° <θ <90 °) by pressing and then inserted. At this time, since the fin 2 is inserted so that the fin collar 6 is vertical, even if a clearance (gap) occurs between the heat transfer tube 1 and the insertion hole 4 due to processing variation or the like, the fin 2 When the force 18 due to the spring back acts on the collar 6, the fin collar 6 can be brought into close contact with the heat transfer tube 1, and for example, heat transfer performance can be improved. And the position shift etc. of the fin 2 by the vibration etc. before joining can be prevented.

Embodiment 5 FIG.
FIG. 9 is a diagram showing a configuration of a refrigeration cycle apparatus according to Embodiment 5 of the present invention. In the refrigeration cycle apparatus of FIG. 9, a compressor circuit, a condenser 200, an expansion valve 300, and an evaporator 400 are connected by piping to form a refrigerant circuit (refrigerant circulation circuit). Here, the level of temperature and the level of pressure are not particularly determined in relation to absolute values, but are relatively determined in terms of the state and operation of the refrigerant in the apparatus. .

  The compressor 100 sucks the refrigerant, compresses it, and discharges it in a high temperature / high pressure state. Here, for example, it may be configured by a compressor of a type that can control the number of revolutions by an inverter circuit or the like and adjust the discharge amount of the refrigerant. The condenser 200 serving as a heat exchanger performs heat exchange between air supplied from a blower (not shown) and a refrigerant, for example, and condenses the refrigerant into a liquid refrigerant (condensates and liquefies). is there.

  The expansion valve (pressure reducing valve, throttle device) 300 expands the refrigerant by reducing the pressure. For example, it is constituted by a flow rate control means such as an electronic expansion valve, but may be constituted by an expansion valve having a temperature sensing cylinder, a refrigerant flow rate adjustment means such as a capillary tube (capillary), or the like. The evaporator 400 evaporates the refrigerant by heat exchange with air or the like to form a gas (gas) refrigerant (evaporate gas).

  Here, the flat tube heat exchanger 20 described in the first to fourth embodiments can be used for at least one of the evaporator 400 and the condenser 200. Thereby, heat transfer performance can be improved. By improving the heat transfer performance, an energy-efficient and energy-saving refrigeration cycle apparatus can be obtained.

  Next, operation | movement in each component apparatus of a refrigerating-cycle apparatus is demonstrated based on the flow of the refrigerant | coolant which circulates through a refrigerant circuit. First, the compressor 100 sucks the refrigerant, compresses it, and discharges it in a high temperature / high pressure state. The discharged refrigerant flows into the condenser 200. The condenser 200 performs heat exchange between the air supplied from the blower 500 and the refrigerant, and condenses and liquefies the refrigerant. The condensed and liquefied refrigerant passes through the expansion valve 300. The expansion valve 300 depressurizes the condensed and liquefied refrigerant passing therethrough. The decompressed refrigerant flows into the evaporator 400. The evaporator 400 evaporates the refrigerant by heat exchange with, for example, a heat load (a heat exchange target). The compressor 100 sucks the evaporated gas refrigerant. Here, heat exchange with the heat load is performed in the evaporator 400, but when the heat load is overheated, it may be performed by the condenser 200.

Embodiment 6 FIG.
In the above-described embodiment, the fin collar curved portion 6b of the fin 2 to be joined to the flat heat transfer tube 1 has been described. For example, the fin fin to be joined to the heat transfer tube in which a part of the cross-sectional shape of the tube is curved. It can also be applied to color tunes.

  1 Heat Transfer Tube, 2 Fin, 3 Hole, 4 Insertion Hole, 5 Slit, 6 Fin Collar, 6a Fin Collar Straight Line, 6b Fin Collar Curve, 7 Pilot Hole, 8 Notch, 9 Boundary Line, 10, 11 Pierce Hole , 18 Springback force, 20 flat tube heat exchanger, 100 compressor, 200 condenser, 300 expansion valve, 400 evaporator.

Claims (8)

A heat transfer tube having a curved cross-sectional shape;
A plate-like fin having an insertion hole formed in accordance with the shape of the heat transfer tube,
The fin has a fin collar that rises along an edge of the insertion hole, and has a fin collar that is divided into a plurality of pieces by a notch and is in contact with the curved portion of the heat transfer tube. vessel. The heat transfer tube is a tube whose cross section is a flat shape with a long side as a straight line and a short side as a semicircular curve,
The fin collar of the fin is divided into a fin collar linear portion that contacts the long side of the heat transfer tube and the notch formed radially from the center of the semicircle, and is a fin that is brought into contact with the short side of the heat transfer tube The heat exchanger according to claim 1, wherein the heat exchanger is configured by a color curved portion.   3. The heat exchanger according to claim 1, wherein the notch has a piercing hole at a terminal portion with an edge side of the insertion hole.   The heat exchanger according to claim 1 or 2, wherein the notch has a semicircular end portion on the edge side of the insertion hole.   The heat exchanger according to any one of claims 1 to 4, wherein the notch is notched to a part of an edge of the insertion hole. When manufacturing the heat exchanger according to any one of claims 1 to 5,
A step of performing press working to raise the fin collar of the fin to an acute angle;
And a step of inserting a heat transfer tube into the insertion hole so that the fin collar and the heat transfer tube are in vertical contact with each other.   The method for manufacturing a heat exchanger according to claim 6, wherein the acute angle is an angle of 45 ° or more and less than 90 °. A compressor that compresses and discharges the refrigerant; a condenser that condenses the refrigerant by heat exchange; a throttling device that depressurizes the refrigerant related to condensation; and A refrigerant circuit is configured by connecting a pipe with an evaporator that evaporates
A refrigeration cycle apparatus characterized in that at least one of the evaporator and the condenser is the heat exchanger according to any one of claims 1 to 5.

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