JP5195733B2 - Heat exchanger and refrigeration cycle apparatus equipped with the same - Google Patents

Description

  The present invention relates to a heat exchanger and a refrigeration cycle apparatus such as an air conditioner and a refrigerator-freezer provided with the heat exchanger.

  Conventionally, as a heat exchanger mounted on a refrigeration cycle apparatus such as an air conditioner, there is a so-called plate fin and tube type (see Patent Document 1, FIG. 26). The heat exchanger includes a pair of headers that extend vertically and are arranged to face each other, and flat heat transfer tubes that are connected to each header on both sides and are laid in a plurality of stages in the vertical direction. Is inserted into the plate fin for heat exchange. A refrigerant flows in the flat heat transfer tube, and an inflow pipe into which the refrigerant flowing through the refrigeration cycle apparatus flows is provided above one header, and an outflow pipe from which the refrigerant flows out is provided below the other header. The refrigerant that has flowed in from the inflow pipe is configured to exchange heat with the air flowing outside the heat exchanger while branching into the plurality of flat heat transfer pipes and flowing. The heat transfer area is increased by the plate-like fins.

  In addition, the heat transfer pipe bent into a U shape provided with a plurality of flow paths through which the working fluid flows inside the flat cross section, the end of the heat transfer pipe communicated, and the inflow pipe and the outflow pipe for the working fluid were connected. A header, a first vertical partition plate in the header longitudinal direction that separates a space that is provided in the header and communicates from the inflow pipe to the heat transfer pipe, and a space that communicates from the heat transfer pipe to the outflow pipe, and an adjacent U-shaped transfer A second vertical partition plate in the header longitudinal direction that is provided between the heat tubes and separates the header inner space into two or more with respect to the gas flow direction; and a horizontal partition plate that separates both ends of the U-shaped heat transfer tube; Which constitutes a refrigerant flow that is a counterflow or a parallel flow with respect to the gas flow direction (see Patent Document 1 and FIG. 1).

  Also, for example, in the case of a condenser, one end of a tubular connection pipe is expanded, and is deformed into a flat shape by being crushed by a press or the like, and a connection member that connects the flat heat transfer pipe and the circular connection pipe from the compressor (See Patent Document 2).

JP 2003-287390 A (FIGS. 1 and 26) Japanese Patent Laying-Open No. 2008-261615 (FIG. 5)

  In the heat exchanger where the flow path of the flat heat transfer tube is connected with a pair of headers as in the conventional plate fin and tube type, if the air flowing in from the front has a wind speed distribution, Can be a slow part. In the portion where the wind speed is fast, heat exchange with the refrigerant flowing in the flat heat transfer tube is promoted more than in the portion where the wind speed is slow, but in the portion where the wind speed is slow, the heat exchange amount decreases. Thus, in the heat exchanger, the amount of heat exchange between the refrigerant flowing in each flat heat transfer tube and the air becomes uneven, and the heat exchange performance as a whole decreases. Furthermore, since many flat heat transfer tubes are connected to one header in a heat exchanger, for example, when this heat exchanger is used as an evaporator and the inflowing refrigerant becomes a two-phase flow of gas and liquid, gravity etc. As a result, the refrigerant having a high liquid ratio flows through the flat heat transfer tube on the lower side, and the refrigerant having a high gas ratio flows through the flat heat transfer tube on the upper side. For this reason, the state of the refrigerant flowing through each flat heat transfer tube is different between the upper and lower sides, the amount of heat exchange between the refrigerant flowing through each flat heat transfer tube and the air becomes uneven, and the heat exchange performance decreases. That is, there has been a problem that the heat exchange performance of the heat exchanger is deteriorated due to the wind speed distribution flowing from the front surface or the non-uniformity of the refrigerant state flowing through the flat heat transfer tube.

  Thus, in order to solve the problem that the state of the refrigerant flowing through each flat heat transfer tube becomes uneven, as shown in FIG. 1 of Patent Document 1, a partition plate is provided in the header, and the refrigerant flowing through the flat heat transfer tube There is a structure in which a plurality of flow paths are provided. In that case, by adjusting the length of the path of the refrigerant flowing through the flat heat transfer tube with respect to the wind speed distribution, it is possible to prevent the heat exchanger performance from being deteriorated with respect to the wind speed distribution.

  However, such a header structure is a configuration in which the ends of the heat transfer tubes are connected together, and it is difficult to change the determined refrigerant flow path once determined. For example, if the refrigerant flow path is changed due to the generation of a wind speed distribution or the like, the header structure is redesigned. That is, when this heat exchanger is used in a refrigeration cycle apparatus such as an air conditioner, a header with different specifications is required for each product. As a result, there is a problem that the manufacturing becomes complicated and the cost increases.

  In addition, a connecting member (Patent Document 2) that connects the flat heat transfer tube and the circular tube is used without using a header at the end of the flat heat transfer tube, and a two-stage flat tube is bent into a U-shape. A configuration in which the heat transfer tubes are connected to each other is also possible. If the ends of multiple flat heat transfer tubes are connected by a circular tube without using a header, multiple paths can be configured in the heat exchanger, and the flow of the refrigerant can be easily changed. The degree of freedom of the channel configuration can be improved.

  However, in the case where two flat heat transfer tubes are connected by a single circular tube, it is necessary to configure the circular tube with a diameter of a certain degree or more in consideration of the refrigerant flow rate. The connecting circular tube is bent in a U shape and connected to a two-stage flat heat transfer tube. The minimum radius of bending in a U shape depends on the diameter of the circular tube to be bent. That is, the interval between the flat heat transfer tubes in the step direction depends on the interval when the circular tube is U-shaped, and cannot be made so small. On the other hand, when the diameter of the circular tube is reduced, there is a problem in that the cross-sectional area of the flow path is reduced, and the pressure loss of the refrigerant flowing therethrough is increased.

  Further, when the connecting joint that connects the flat heat transfer tube and the circular tube is formed by a press or the like, the difference in shape between the flat heat transfer tube and the circular tube is large, so that the amount of deformation must be increased. In that case, a change in thickness occurs, and the thickness becomes thin, and deformation and cracking easily occur. For this reason, there is a problem that the defect rate increases and the breakdown voltage decreases.

The present invention has been made to solve the above-described problems, and the flow of refrigerant flowing through the heat exchanger can be freely set without being limited by the configuration of the header. It is an object of the present invention to obtain a heat exchanger that can reduce the interval and can be downsized or increase the amount of heat exchange.
Furthermore, it is an object of the present invention to improve the reliability of the heat exchanger by preventing an increase in defective products and a decrease in pressure resistance at the connecting portion of the two-stage flat heat transfer tube.
It is another object of the present invention to provide a refrigeration cycle apparatus that includes a heat exchanger that can be downsized or increase the amount of heat exchange, has high reliability, can be downsized, and has good heat exchange performance.

The heat exchanger according to the present invention is parallel to each other at a predetermined interval, and a plurality of plate-like fins through which gas flows between each other, and the plate-like fins are penetrated in the parallel direction of the plate-like fins. provided, cross-section with a flat shape, a flat heat exchanger tube which forms a plurality of stages in a direction perpendicular to the respective flow direction of the parallel direction and the gas of the plate-like fins at one end of the heat exchanger, the And connecting portions that connect the two-stage ends of the flat heat transfer tubes that form a plurality of stages, and the flat heat transfer tubes are disposed so that the flat surfaces face each other in the direction of the plurality of stages. , Provided in the gas flow direction by a plurality of partitions extending in the parallel direction of the plate-like fins therein, and having four or more flat heat transfer tube flow paths through which the refrigerant flows, the connecting portion is arranged in flow direction of the gas 2 Or a three and round tube bent into a U-shaped, and a connecting joint to connect with each end portion provided the flat heat transfer tube of yen tube and the circular tube, the flattened heat transfer pipe flow in sum and sum comparable flow path cross-sectional area of the circular tube cross-sectional area of the road, a configuration of connecting the flat heat transfer tubes 2 stages via the circular tube, the connecting joint has one end Each of the two or three circular tubes is joined by brazing, and the other end portion has a flat heat transfer tube connecting portion joining the flat heat transfer tubes by brazing, Inside the connection joint, the refrigerant flows in the direction in which the refrigerant flows between the connection end of the circular tube connected to the circular tube connection portion and the connection end of the flat heat transfer tube connected to the flat heat transfer tube connection portion. A space having a width equal to or larger than the outer diameter of the circular pipe is formed .

In the refrigeration cycle apparatus according to the present invention, at least a compressor, a condenser, a throttling device, and an evaporator are sequentially connected by piping so that a refrigerant is circulated, and the heat exchanger having the above-described configuration is the evaporator or It is used as a condenser.

According to the present invention, the flow of the refrigerant flowing through the heat exchanger can be freely set without being limited by the configuration of the header, the interval between the flat heat transfer tubes in the step direction can be reduced, and in the case of a similar amount of heat exchange It is possible to obtain a heat exchanger that can be reduced in size and that can increase the amount of heat exchange in the case of a similar size.
Furthermore , a heat exchanger having a highly reliable connection portion that can reduce the diameter of one circular tube, reduce the deformation amount of the connection portion, prevent an increase in defective products and a decrease in pressure resistance during molding, and has a highly reliable connection portion. realizable.
Further, the refrigeration cycle apparatus is provided with a heat exchanger capable of reducing the size or increasing the amount of heat exchange, and a refrigeration cycle apparatus having high reliability, capable of downsizing, and good heat exchange performance can be obtained. .

It is a perspective view which shows the heat exchanger which concerns on Embodiment 1 of this invention. It is a circuit block diagram which shows the refrigerant circuit of the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. It is a section lineblock diagram showing the indoor unit concerning Embodiment 1 of the present invention. It is sectional drawing which shows the flat heat exchanger tube which concerns on Embodiment 1 of this invention. FIG. 5 is a cross-sectional view taken along line VV in FIG. 1 according to the first embodiment of the present invention. It is a perspective view which concerns on Embodiment 1 of this invention and shows the connection part vicinity of an inflow tube and an outflow tube. It is a perspective view which concerns on Embodiment 1 of this invention and shows the heat exchanger of a comparative example. It is a top view (Drawing 8 (a)), a front view (Drawing 8 (b)), and a side view (Drawing 8 (c)) which show a comparative example of a connection joint concerning Embodiment 1 of the present invention. It is a perspective view which concerns on Embodiment 1 of this invention and shows the connection part of a flat heat exchanger tube. It is a perspective view which shows the connection joint which concerns on Embodiment 1 of this invention. It is a top view (Drawing 11 (a)), a front view (Drawing 11 (b)), and a side view (Drawing 11 (c)) which show a connection joint concerning Embodiment 1 of the present invention. It is explanatory drawing explaining the space | interval of the step direction of the flat heat exchanger tube of the heat exchanger which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the front surface of the comparative example of the heat exchanger which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the front surface of the heat exchanger which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows the front surface of the heat exchanger which concerns on Embodiment 1 of this invention. It is a perspective view which shows the heat exchanger which concerns on Embodiment 2 of this invention. It is a perspective view which shows the connection part of the flat heat exchanger tube which concerns on Embodiment 2 of this invention. It is a perspective view which shows the heat exchanger which concerns on Embodiment 2 of this invention. It is a perspective view which shows the heat exchanger which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the flat heat exchanger tube which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the heat exchanger which concerns on Embodiment 2 of this invention. It is explanatory drawing which shows the cross section of the connection part which concerns on Embodiment 3 of this invention. It is a graph which concerns on Embodiment 3 of this invention, and shows the change of refrigerant | coolant temperature and air temperature. It is a graph which concerns on Embodiment 3 of this invention, and shows the change of refrigerant | coolant temperature and air temperature. It is explanatory drawing which shows the cross section of the connection part which concerns on Embodiment 3 of this invention.

Embodiment 1 FIG.
1 is a perspective view showing a heat exchanger according to Embodiment 1 of the present invention, FIG. 2 is a circuit configuration diagram showing a refrigerant circuit of an air conditioner, for example, as a refrigeration cycle apparatus, and FIG. 3 shows an example of an indoor unit. 4 is a cross-sectional view showing a flat heat transfer tube according to the present embodiment, and FIG. 5 is a cross-sectional view taken along line VV in FIG. The heat exchanger 20 according to the present embodiment is generally called a plate fin and tube type.

  As shown in FIG. 1, a heat exchanger 20 mounted on a refrigeration cycle apparatus such as an air conditioner or a refrigerator is composed of a heat transfer tube 1 having a flat cross section (hereinafter referred to as a flat heat transfer tube) and a plate-like fin 2. Composed. The plurality of plate-like fins 2 are juxtaposed in parallel in the length direction (for example, the A direction) with a predetermined interval from each other, and gas, for example, indoor air, flows between the individual plate-like fins 2 in the D direction. To do. The flat heat transfer tube 1 is provided so as to penetrate each of the plate-like fins 2 in the parallel direction (A direction) of the plate-like fins 2 and is laminated in a plurality of stages, for example, eight stages in the step direction (B direction). That is, the flat heat transfer tubes 1 are arranged so that the flat surfaces face each other in the direction (B direction) forming a plurality of stages, and the parallel direction (A direction) of the plate-like fins 2 and the gas flow direction (D direction). A plurality of stages are formed in a direction (B direction) orthogonal to each. The flat heat transfer tube 1 has a plurality of flat heat transfer tube flow paths through which the refrigerant flows in the penetration direction (direction A). Further, the ends of the two flat heat transfer tubes 1 are connected to form the refrigerant flow path, but at least one of the connection portions 18 that connect the two end portions of the flat heat transfer tubes 1 to each other. Two connecting portions are connected via a plurality of, for example, two circular heat transfer tubes 8 bent into a U shape (hereinafter referred to as circular tubes). That is, the connecting portion 18 has a plurality of U-shaped bent tubes 8 arranged in the gas flow direction (D direction), and the two-stage flat heat transfer tubes 1 are connected via the circular tubes 8. The In the configuration shown in FIG. 1, when connecting the two-stage flat heat transfer tubes 1, one flat heat transfer tube 1 and the circular tube 8 are connected via the connection joint 9, and again the circular tube 8 is connected via the connection joint 9. The other flat heat transfer tube 1 is connected. In this Embodiment, the inflow piping 3 and the outflow piping 4 are connected to the one end side of the heat exchanger 20, and the U-shaped circular pipe 8 is used for the connection of the flat heat exchanger tubes 1 in this one end side. The other end is connected by a flat heat transfer tube 1a bent in a U-shape to form a refrigerant flow path from the inflow pipe 3 to the outflow pipe 4. In the present embodiment, a plurality of rows, for example, two rows of heat exchangers 20a and 20b are arranged in parallel in the C direction to constitute the heat exchanger 20 as a whole.

  As shown in FIG. 2, the air conditioner includes an outdoor unit 41 and an indoor unit 42. The outdoor unit 41 stores a compressor 31, a four-way valve 32, an outdoor heat exchanger 33, an expansion device 34, an outdoor fan 35 and an outdoor fan motor 36. The indoor unit 42 stores the indoor heat exchanger 20, the indoor blower 37, and the indoor blower motor 38. The heat exchanger having the configuration shown in FIG. 1 is used for one or both of the two heat exchangers. Here, for example, the heat exchanger 20 according to the present embodiment is used as an indoor heat exchanger. Use. The outdoor unit 41 and the indoor unit 42 are connected by refrigerant pipes 39 and 40. In the figure, the flow direction of the refrigerant is when the solid arrow is during cooling and the dotted arrow is during heating, and the flow direction of the refrigerant is switched by the four-way valve 32.

  A case where the air conditioner performs a cooling operation will be described. As indicated by the solid line in the four-way valve 32, refrigerant piping is connected, and the indoor heat exchanger 20 is operated as an evaporator and the outdoor heat exchanger 33 is operated as a condenser. At least the compressor 31, the condenser 33, the expansion device 34, and the evaporator 20 are sequentially connected by piping, and the refrigerant is circulated to constitute a refrigeration cycle apparatus. At this time, the low-temperature and low-pressure gas refrigerant flowing inside the refrigerant circuit is compressed by the compressor 31 to become a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant exchanges heat with the outdoor air in the outdoor heat exchanger 33, and the refrigerant itself condenses to become a high-pressure and low-temperature liquid refrigerant. Becomes a refrigerant. Then, the indoor heat exchanger 20 exchanges heat with the indoor air flowing between the plate fins 2 to evaporate and return to the compressor 31. The indoor heat exchanger 20 functions as an evaporator and the refrigerant evaporates, so that the indoor air is cooled to cool the room. Further, in the heating operation, the refrigerant pipe is connected in the four-way valve 32 as indicated by the dotted line, and the refrigerant is circulated as indicated by the dotted arrow. By causing the indoor heat exchanger 20 to function as a condenser and condensing the refrigerant, the indoor air is heated by heating the indoor air. Although not shown in FIG. 2, each of the indoor units 42 and the outdoor units 41 includes one control device, or one common control device, the rotational speed of the compressor 31, the connection of the four-way valve 32, and the throttle device. 34, the number of rotations of the motors 36 and 38 of the blowers 35 and 37, and the like are controlled.

  The indoor unit 42 is installed on a wall 43 of a room to be air-conditioned, as shown in FIG. A suction grill 44 that serves as a suction port for indoor air and a mesh-like filter 45 that removes dust are disposed on the upper portion of the indoor unit 42. Furthermore, the heat exchanger 20 according to the present embodiment is arranged on the front side and the upper side of the blower 37 so as to surround the blower 37. Moreover, the front surface of the indoor unit 42 is covered with a front panel, and an air outlet 46 is opened below the indoor unit 42. This blower 37 is, for example, a once-through fan. In the figure, solid arrows indicate the refrigerant inflow and outflow directions, white arrows D indicate the air flow direction, and dotted arrows O indicate the rotation direction of the blower 37.

  In the indoor unit 42 configured as described above, when the operation is started, the blower 37 rotates in the direction of the dotted arrow O. After the room air is sucked in through the suction port 44 and dust is removed by the filter 45, it flows between the plate-like fins 2 of the heat exchanger 20 as shown in the D direction. In the heat exchanger 20, the refrigerant circulates in a refrigerant flow path formed by a flat heat transfer pipe and a circular pipe from the inflow pipe 3 to the outflow pipe 4. The air that has flowed into the heat exchanger 20 is heated by heat exchange with the refrigerant flowing through the circular tubes and the flat heat transfer tubes, heated, cooled, cooled, or dehumidified, and sucked into the blower 37. Thereafter, the airflow blown out from the blower 37 is guided to the air passage, travels toward the air outlet 46, and blows out from the air outlet 46 into the room, thereby air conditioning the room.

  Hereinafter, the configuration of the heat exchanger 20 will be described in more detail. As shown in FIG. 4, the flat heat transfer tube 1 is a heat transfer tube having a flat cross section with an opposing flat surface. In the flat heat transfer tube 1, the flat heat transfer is a plurality of, for example, eight refrigerant channels arranged in the D direction through which gas flows by a plurality of, for example, seven partition walls 47 extending in the parallel direction (A direction) of the plate-like fins 2. It has a heat pipe channel 5. The eight flow channels 5 in the flat heat transfer tube are provided in, for example, one row in the long axis direction (D direction) in the flat cross section. In the cross section shown in FIG. 5, two rows of plate-like fins 2 constituting two heat exchangers 20a and 20b arranged side by side in the row direction (C direction) are shown. In one plate-like fin 2, a collar 6 for fixing the flat heat transfer tube 1 is formed around the flat heat transfer tube 1. The collar 6 and the flat heat transfer tube 1 are joined by brazing, an adhesive, or the like, or mechanically crimped. One plate-like fin 2 has a slit portion 7 between two flat heat transfer tubes 1 in the step direction (B direction) for improving heat exchange performance. Specifically, a part of the plate-like fin 2 is cut and raised to constitute the slit portion 7. In addition, the flow path 5 in a flat heat exchanger tube is not restricted to eight pieces, but is comprised by about 2-16 pieces. Moreover, the slit part 7 may have another shape, and may not be provided due to dew condensation or frost formation. With respect to the plate-like fin 2, a white arrow D is a gas flow direction and may be arranged in either direction. A white arrow Q indicates a direction in which the flat heat transfer tube 1 is inserted from one of the plate-like fins 2 at the time of manufacture. The cross-sectional shape of the flat heat transfer tube 1 is suitable also from being inserted in this way.

  As shown in FIG. 1, one end portion in the A direction of the heat exchanger 20 has two U-shaped bent tubes 8 arranged in the gas flow direction (D direction), and the upper or lower flat transmission is arranged. Connect to heat tube 1. The connection joint 9, the flat heat transfer tube 1, and the U-shaped circular tube 8 are joined by brazing in the furnace, high-frequency brazing, or torch brazing. In addition, when the pressure of the refrigerant is not so high, bonding with an adhesive is also possible. The connection joint 9 is processed by pressing or cutting. The material of the flat heat transfer tube 1 and the circular tube 8 is made of, for example, aluminum or copper. The material of the connection joint 9 is also made of, for example, aluminum or copper. The other end in the A direction connects the flat heat transfer tube 1 to the upper or lower flat heat transfer tube 1 with a flat heat transfer tube 1a bent into a U shape.

  When operating the heat exchanger 20 according to the present embodiment as an evaporator, the refrigerant flows in from the inflow pipe 3 provided in the central portion in the B direction of the first row shown in FIG. The refrigerant flows out of 4. While the refrigerant flows from the inflow pipe 3 to the outflow pipe 4, the refrigerant exchanges heat with air flowing outside the heat exchanger that is blown from the direction D to the front surface of the heat exchanger 20 by a blower (not shown). Here, for example, a configuration is shown in which the refrigerant flows in two passes, which flows in from two inflow pipes 3, flows through the flat heat transfer tubes 1 in the upper half and the lower half, and flows out to the two outflow pipes 4. For example, the lower half path will be described in detail. The inflow pipe 3 is connected to the flat heat transfer tube 1 in the fourth row from the bottom of the first row. The refrigerant flowing in from the lower inflow pipe 3 flows from the right side to the left side of the fourth-stage flat heat transfer tube 1 toward the drawing in FIG. 1, and passes through the U-shaped flat heat transfer tube 1a at the left end to form three steps. It flows from left to right through the flat heat transfer tube 1 of the eye. At the right end, the second flat heat transfer tube 1 flows from right to left through the two U-shaped circular tubes 8. Next, the refrigerant flowing to the right end through the first flat heat transfer tube 1 flows through the two U-shaped circular tubes 8 to the first row in the second row. In the second row, the flat heat transfer tube 1 flows from the first stage to the fourth stage and flows out from the outflow pipe 4. The same applies to the upper half path.

  FIG. 6 is a perspective view showing a portion where the flat heat transfer tube 1 and the inflow pipe 3 or the outflow pipe 4 are connected by the connection joint 11. When connecting the flat heat transfer tube 1 having a plurality of refrigerant flow paths and the inflow pipe 3 or the outflow pipe 4 formed of one flow path, the sum of the cross-sectional area of the flat heat transfer pipe 1 and the circular tubes 3, 4 The flow path cross-sectional area is configured to the same extent. By configuring the channel cross-sectional areas to be approximately the same, a heat exchanger with good heat exchange performance can be obtained without increasing the pressure loss of the refrigerant flowing through the refrigerant channel.

  Next, in one end portion of the heat exchanger 20, heat exchange in which the connecting portions 18 of the flat heat transfer tubes 1 are connected by a single U-shaped circular tube 10 in the upper and lower stages of the inflow pipe 3 and the outflow pipe 4. The configuration of a comparative example of the vessel is shown in FIG. As described above, the U-shaped circular tube 10 is used to form the two-stage flat heat transfer tube 1 without using the header in which the flow path is collectively formed inside the end of the flat heat transfer tube 1 as in the conventional apparatus. If it makes the structure which connects edge parts, the freedom degree at the time of connecting the flat heat exchanger tube 1 and comprising a refrigerant | coolant flow path will increase. For example, in FIG. 7, similarly to the configuration of FIG. 1, two rows of heat exchangers 20a and 20b are connected to form a refrigerant flow path, and there are two paths, and the length of the flat heat transfer tube 1 in each path is It is the same. Depending on the air flow to be heat exchanged, it may be desired to change the number of passes or the length of the passes. The configuration in which the circular pipe 10 is connected without using the header can be realized by changing the connection between the U-shaped circular pipe 10 and the inflow pipe 3 or the outflow pipe 4. As an example, if one path is changed, for example, the two outflow pipes 4 are connected by the U-shaped circular pipe 10 like the other connecting portions 18, and one of the two inflow pipes 3 is used as the outflow pipe. Can be changed. On the other hand, when a header is used as in the prior art, the header itself needs to be redesigned and manufactured again, which is complicated. That is, in the configuration in which the two-stage flat heat transfer tubes 1 are connected by the circular tube 10 without using a header, a plurality of paths are formed in the heat exchanger 20 and the flow of the refrigerant can be easily changed. The degree of freedom of the refrigerant flow path configuration can be improved without being limited by the configuration.

However, when the upper and lower flat heat transfer tubes 1 are connected by a single circular tube 10, if the flow passage cross-sectional area of the flat heat transfer tube 1 and the flow passage cross-sectional area of the circular tube 10 are made similar, It is necessary to configure with a circular tube 10. In the connecting portion 18, the circular tube 10 to be connected is bent in a U shape and connected to the two-stage flat heat transfer tube 1, but the minimum radius to be bent in the U shape depends on the diameter of the circular tube to be bent. In the configuration shown in FIG. 7, the other end of the heat exchanger 20 is connected by a U-shaped flat heat transfer tube 1a, and the minimum radius for bending the flat heat transfer tube 1a into a U-shape is one on one end side. It can be made smaller than the minimum radius for bending the circular tube 10 into a U-shape. That is, the interval (stage pitch) in the step direction (B direction) of the heat exchanger 20 is determined by the diameter of the circular tube 10 on one end side connected by the circular tube 10, and therefore, between the flat heat transfer tubes 1 in the step direction. The interval increases, and the size of the entire heat exchanger 20, here, the front area represented by (length in the A direction) × (length in the B direction) must be increased. Further, when the front area of the heat exchanger 20 is not increased, the number of stages of the flat heat transfer tubes 1 is reduced, leading to a decrease in the amount of heat exchange.
On the other hand, when the diameter of the circular tube 10 is reduced in order to reduce the step pitch, the difference between the flow passage cross-sectional area of the flat heat transfer tube 1 and the flow passage cross-sectional area of the circular tube 10 increases, and the pressure loss increases and heat increases. There is a problem that the exchange efficiency is reduced.

  FIG. 8 is a view showing a connection joint 12 for connecting the flat heat transfer tube 1 and one circular tube 10 used in the comparative example of FIG. 7, FIG. 8 (a) is a top view, and FIG. 8 (b) is a top view. FIG. 8C is a front view, and FIG. One end portion of the connection joint 12 has a flat heat transfer tube connection portion 12a to which the flat heat transfer tube 1 is connected, and the other end portion has a circular tube connection portion 12b to which the circular tube 10 is connected. Since the flow passage cross-sectional area of the flat heat transfer tube 1 and the flow passage cross-sectional area of the circular tube 10 are configured to be approximately the same, the circular tube 10 has a diameter of a certain degree or more. For this reason, the width difference EE between the flat heat transfer tube 1 and the circular tube 10 shown in the top view of FIG. 8A and the width difference FF shown in the front view of FIG. 8B are large. The connection joint 12 is formed by, for example, a press. At this time, since the difference in shape between the flat heat transfer tube 1 and the circular tube 10 is large, the amount of deformation must be increased. When the amount of deformation is increased, thickness change occurs and the thickness becomes thin, and deformation and cracking tend to occur. Therefore, problems such as an increase in defect rate and a decrease in breakdown voltage occur.

  As described above, in the configuration in which the two flat heat transfer tubes 1 are connected by the single circular tube 10, the degree of freedom can be improved in the configuration of the refrigerant flow path, but there is a problem in the defective rate of manufacture and the heat exchange performance. . Therefore, in the present embodiment, as shown in FIG. 1, the flat heat transfer tube 1 is replaced with a plurality of U-shaped circular tubes, for example, two U-shaped circular tubes at the connection portion 18 at one end of the heat exchanger 20. 8 is connected. FIG. 9 is a perspective view showing a portion where the flat heat transfer tube 1 and a plurality of, for example, two U-shaped circular tubes 8 are connected by the connection joint 9. 10 is a perspective view showing the connection joint 9, FIG. 10 (a) is a perspective view seen from the flat heat transfer tube connecting portion 9a, and FIG. 10 (b) is a perspective view seen from the circular tube connecting portion 9b. FIG. One end portion of the connection joint 9 has a flat heat transfer tube connection portion 9a to which the flat heat transfer tube 1 is connected, and the other end portion has a circular tube connection portion 9b to which each of the U-shaped circular tubes 8 is connected. . Moreover, FIG. 11 is a figure which shows the connection joint 9 which connects the flat heat exchanger tube 1 and the two circular tubes 8, FIG. 11 (a) is a top view, FIG.11 (b) is a front view, FIG. c) is a side view.

An example of the size of the flat heat transfer tube 1, the circular tube 8, and the heat exchanger 20 configured as shown in FIG.
Regarding the plate-like fins 2, the parallel pitch (Fp) = 0.001m to 0.002m, the thickness of the plate-like fins (Ft) = 0.00009m to 0.00011m, and the width of the plate-like fins (FL) = 0.001m. ~ 0.03m. As for the flat heat transfer tube 1, the long axis length (Dl) of the cross section of the flat heat transfer tube 1 is 0.01 m to 0.02 m, and the short axis length (Ds) of the cross section of the flat heat transfer tube 1 is 0.002 m. The step pitch of the flat heat transfer tube 1 is 0.005 m to 0.03 m, and the number of flow paths in the flat heat transfer tube 1 is 3 to 10.
In addition, regarding said dimension, it is an example and is not limited to the said range. For example, when the size of the heat exchanger or the flow rate of the refrigerant changes according to the heat exchange performance of the heat exchanger 20, the above range is different.

  In the present embodiment, as shown in FIG. 1, the flat heat transfer tube 1 and two circular tubes 8 are connected at one end of the heat exchanger 20. When the flat heat transfer tube 1 having a plurality of refrigerant flow paths and the two circular tubes 8 are connected, the sum of the cross-sectional areas of the flat heat transfer tubes 1 and the sum of the cross-sectional areas of the circular tubes 8 are configured to be approximately the same. To do. By configuring the channel cross-sectional areas to be approximately the same, a heat exchanger with good heat exchange efficiency can be obtained without increasing the pressure loss of the refrigerant flowing through the refrigerant channel. In this case, since the two circular tubes 8 are connected, the circular tube 8 has a diameter of a certain degree or more, but can be configured with a smaller diameter than that of the single circular tube 10. Therefore, the width difference E between the flat heat transfer tube 1 and the circular tube 8 shown in the top view of FIG. 11 (a) and the width difference F shown in the front view of FIG. 11 (b) are shown in FIG. It becomes smaller than EE and FF. For this reason, when manufacturing the connection joint 9, the amount of deformation is not as great as when the connection joint 12 is manufactured. Compared with the case of manufacturing a large amount of deformation, the thickness change is less likely to occur, and cracks and the like can be prevented. Therefore, it is possible to prevent the defect rate from increasing and the breakdown voltage from decreasing.

  That is, in the configuration in which a plurality of circular pipes 8 are connected, the amount of deformation at the time of forming the connection joint can be reduced, so that the amount of change in wall thickness can be reduced and cracking can be prevented. For this reason, reliability, such as a pressure | voltage resistant and corrosion, is not impaired. Furthermore, in the connection part 18 that connects the two-stage flat heat transfer tubes 1, the diameter of the circular tube 8 to be connected can be reduced, so that the minimum radius for bending the circular tube 8 into a U shape can be reduced. Therefore, the step pitch in the B direction of the flat heat transfer tube 1 can be reduced. On the other hand, reducing the diameter of the circular tube 8 increases the pressure loss of the refrigerant, but using two circular tubes 8 can prevent an increase in pressure loss.

  FIG. 12 is an explanatory diagram showing a configuration of a part of the heat exchanger according to the present embodiment, FIG. 12 (a) relates to the heat exchanger according to the present embodiment, and FIG. 12 (b) is a comparative example. It is explanatory drawing which shows the structure of a part when connecting between the flat heat exchanger tubes 1 of an upper-lower stage with the one circular tube 10. FIG. In the figure, P and PP are intervals in the step direction (B direction) of the flat heat transfer tube 1, and R and RR indicate radii of bent portions when the circular tubes 8 and 10 are bent in a U shape.

  For example, in the case of using a flat heat transfer tube 1 having a long axis (Dl) of 14 mm, a short axis (Ds) of 4 mm, a number of channels 5 in the flat tube, and a thickness of 0.4 mm, the same as the flow channel. The inner diameter of one circular pipe 10 having a flow path cross-sectional area of about 4.4 mm is about 4.4 mm. If the thickness of the circular tube is 0.5 mm, the outer diameter of the circular tube 10 is 5.4 mm, but for the sake of simplicity, the general size is an outer diameter of 6 mm and an inner diameter of 5 mm. In general, when a circular pipe is bent into a U shape, the bending radius is required to be equal to or greater than the outer diameter. Therefore, when one circular pipe 10 is used, the step pitch is about 12 mm, which is twice the outer diameter. Therefore, when it is desired to set the step pitch of the flat heat transfer tube 1 to 10 mm, it is necessary to use a circular tube having an outer diameter of 5 mm. If the thicknesses are the same, the inner diameter is 4 mm, which is about 4.4 mm or less, so that the cross-sectional area of the pressure loss is larger than the pressure loss of the flow path of the flat heat transfer tube 1. Although the thickness of the circular pipe 10 can be reduced to increase the cross-sectional area of the flow path, the thickness of the circular pipe 10 cannot be reduced so much in consideration of pressure resistance and corrosion. However, in the heat exchanger 20 according to the present embodiment, if two circular tubes 8 having an outer diameter of 5 mm are used, a channel cross-sectional area having an inner diameter of 4.4 mm or more can be obtained. For this reason, it is possible to prevent the pressure loss from increasing without increasing the step pitch of the flat heat transfer tube 1. Specifically, in FIGS. 12A and 12B, when the refrigerant is flowed so as to have the same pressure loss, in the above configuration example, in FIG. 12A, R = 5 mm and P = 10 mm. However, in FIG. 12B, RR = 6 mm and PP = 12 mm. Thus, compared with the case where it connects with the one circular pipe 10, when connecting with the two circular pipes 8, the step pitch of the flat heat exchanger tube 1 is set to P / PP = 10/12 = 5 / Can be reduced to 6.

  FIG. 13 is a block diagram showing a heat exchanger 20 in which the flat heat transfer tube 1 is connected by one circular tube 10 as a comparative example, and FIGS. 14 and 15 show the flat heat transfer tube 1 connected by two circular tubes 8. 1 is a configuration diagram showing a heat exchanger 20. 13, 14, and 15 are front views of the heat exchanger 20 as viewed from the flow direction of the air that exchanges heat with the refrigerant. In FIGS. 13 and 14, the front area of the heat exchanger 20 is the same. As shown. FIG. 15 shows a configuration in which the same number of flat heat transfer tubes 1 as in FIG. 13 are used in the step direction (B direction).

  In FIG. 13, the outer diameter of one circular tube 10 cannot be reduced from the point of pressure loss, and the step pitch of the flat heat transfer tube 1 is increased. For this reason, only the 8-stage flat heat transfer tube 1 can be connected with the size of the predetermined front surface area shown in FIG. On the other hand, in FIG. 14, the 12-stage flat heat exchanger tube 1 can be connected. As is clear from comparison between FIG. 13 and FIG. 14, when the flat heat transfer tubes 1 are connected by a circular tube, if they are connected by a plurality of circular tubes 8, the heat loss of the same front area increases the pressure loss. Therefore, the heat exchange amount can be increased and the heat exchange performance can be improved.

  Further, as apparent from comparison between FIG. 13 and FIG. 15, in the heat exchanger 20 configured by the flat heat transfer tubes 1 having the same number of stages, the case where the flat heat transfer tubes 1 are connected by a plurality of circular tubes 8. However, compared with the case where it connects with the one circular pipe 10, if it is set as the same heat exchange amount, a front surface area can be made small. That is, the same number of flat heat transfer tubes 1 can be reduced in the step direction (B direction) of the flat heat transfer tubes 1 without increasing the pressure loss, so that downsizing can be realized.

As described above, in the present embodiment, a plurality of plate-like fins 2 that are arranged in parallel at a predetermined interval and in which gas flows between them, and these plate-like fins 2 are arranged in parallel. A plurality of refrigerants arranged in the direction (A direction) and arranged in the gas flow direction (D direction) by a plurality of partition walls 47 extending in the parallel direction (A direction) of the plate-like fins 2 in a flat cross-sectional shape A flat heat transfer tube 1 having a flow path 5 and a plurality of stages in a direction (B direction) perpendicular to each of the parallel direction (A direction) of the plate-like fins 2 and the gas flow direction (D direction), and a plurality of stages Connecting the two end portions of the flat heat transfer tube 1, and the flat heat transfer tube 1 is arranged so that the flat surfaces face each other in a direction (B direction) in which a plurality of steps are formed. And a plurality of connecting portions 18 arranged in the gas flow direction (D direction). By having a circular tube 8 bent in a U-shape, and connecting the two-stage flat heat transfer tube 1 via the circular tube 8, the flow of the refrigerant flowing through the heat exchanger 20 is limited by the configuration of the header. Can be set freely, the interval between the flat heat transfer tubes 1 in the step direction can be reduced, the size can be reduced in the case of the same heat exchange amount, and the heat exchange amount in the case of the same size It is possible to obtain a heat exchanger that can increase the amount of heat.
Further, by connecting the connecting portions 18 of the two-stage flat heat transfer tubes 1 through a plurality of circular tubes 8 bent in a U shape, the diameter of the single circular tube 8 can be reduced, and the connecting portions 18 can be reduced. By reducing the amount of deformation of the shape, it is possible to prevent an increase in defective products and a decrease in pressure resistance during molding, and it is possible to realize the heat exchanger 20 having the highly reliable connection portion 18.

  In addition, since the sum of the cross-sectional areas of the flow channels 5 in the flat heat transfer tubes and the sum of the cross-sectional areas of the plurality of circular tubes 8 are approximately the same, an increase in pressure loss can be prevented, and heat exchange efficiency can be prevented. There is an effect that a good heat exchanger can be obtained.

  Moreover, the connection part 18 is provided with the connection joint 9 which connects the flat heat exchanger tube 1 and the multiple circular pipes 8, and this connection joint 9 connects each of the multiple circular pipes 8 to one end part. Each of the flat heat transfer tubes 1 and the plurality of circular tubes 8 can be easily connected by including the flat heat transfer tube connection portion 9a that has the connection portion 9b and connects the flat heat transfer tube 1 to the other end. . Furthermore, since the difference in shape between the ends of the flat heat transfer tubes 1 and the ends of the plurality of circular tubes 8 can be reduced, the amount of deformation of the shape of the connection joint 9 can be reduced. For this reason, an increase in defective products and a decrease in pressure resistance during molding can be prevented, and the heat exchanger 20 having the highly reliable connection portion 18 can be realized.

  In the present embodiment, the flat heat transfer tube 1 has eight flat heat transfer tube flow paths 5, but the present invention is not limited to this, and there may be more than eight or less than eight. The same effect is obtained. Further, the plurality of flat heat transfer tube flow paths 5 are arranged in a row in the gas flow direction (D direction), but are arranged in a row in the gas flow direction (D direction) and are vertically arranged in the cross section of the flat heat transfer tube 1. The partition may be formed in the flat heat transfer tube 1 so as to form a row. In the present embodiment, the flat heat transfer tubes 1 at each stage are connected by two circular tubes 8 at one end of the heat exchanger 20, but are connected by more than two circular tubes 8. However, the same effect is obtained.

  Further, in the present embodiment, with respect to the connection of the inflow pipe 3 and the outflow pipe 4, the number of connection pipes is increased and the refrigerant circuit may be complicated. Therefore, one connection pipe as shown in FIG. 6 is used. However, it may be composed of a plurality of circular tubes. If the connection joint 9 shown in the present embodiment that can connect a plurality of circular pipes 8 is used at the portion where the inflow pipe 3 and the outflow pipe 4 are connected to the flat heat transfer pipe 1, the inflow pipe 3 and the outflow pipe 4 Also in the connection portion, the reliability during molding can be improved.

  In the heat exchanger 20 of FIG. 1, the refrigerant pipe located on the upstream side with respect to the air flow direction D is the inflow pipe 3, and the refrigerant pipe located on the downstream side is the outflow pipe 4. It is not limited. When this heat exchanger 20 is used as an evaporator, the refrigerant is arranged to flow from the upstream side to the downstream side with respect to the air flow. On the other hand, in the heating operation, the indoor heat exchanger 20 operates as a condenser, and the outdoor heat exchanger 33 operates as an evaporator. Then, the refrigerant is caused to flow in from the outflow pipe 4 in FIG. 1 and is circulated so as to flow out from the inflow pipe 3. Thus, if it comprises so that the flow of a refrigerant | coolant may circulate reversely by cooling and heating, an evaporator and a condenser can be switched easily. In practice, in the refrigeration cycle shown in FIG. 2, the connection of the flow path is switched by the four-way valve 2 to switch between the cooling operation indicated by the solid arrow and the heating operation indicated by the dotted arrow. Further, by switching the flow direction of the refrigerant in the heat exchangers 20 and 33, when considering the temperature change of the refrigerant in the heat exchanger 20 and the temperature change of the air flow, the air temperature and the refrigerant are both in the cooling operation and the heating operation. Since a temperature difference in temperature can be ensured, a heat exchanger with good heat exchange efficiency can be realized.

  In the configuration of FIG. 1, the connection portion 18 other than the inflow pipe 3 and the outflow pipe 4 is connected by the two circular pipes 8 on one end side of the heat exchanger 20, but is not limited thereto. If it is not necessary to change the refrigerant flow path with respect to the gas inflow direction (D direction), several locations of the connecting portion 18 on this side may be connected by the U-shaped flat heat transfer tube 1a. When not all the step pitches in the B direction need to be configured identically, a portion of the step pitch in the B direction is further increased by connecting several portions with the U-shaped flat heat transfer tubes 1a than connecting with the circular tubes 8. Therefore, when the heat exchange amount is the same, the size can be reduced, and when the heat exchange amount is the same, the heat exchange amount can be increased.

Embodiment 2. FIG.
In the first embodiment, one end of the heat exchanger 20 is provided with two U-shaped circular tubes 8 bent into, for example, a U shape, and the flat heat transfer tube 1 is connected. In the second embodiment of the present invention, another configuration example will be described.

FIG. 16 is a perspective view showing the heat exchanger 20 according to the present embodiment. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. As shown in FIG. 16, in the connection part 18 which connects the edge parts of the flat heat exchanger tube 1 of 2 steps | paragraphs, three U-shaped circular pipes 8 are made into gas of a plurality of circular pipes by the connection joint 13, for example. They are arranged side by side in the flow direction (D), that is, in the long axis direction of the flat heat transfer tube 1.
In the configuration of FIG. 16, three U-shaped circular tubes 8 of FIG. 1 are connected, and the manner of flowing the refrigerant flowing in the heat exchanger 20 is limited by the configuration of the header, as in the first embodiment. It can be set freely without In order to prevent an increase in pressure loss, the sum of the cross-sectional areas of the refrigerant flow paths of the flat heat transfer tubes 1 and the sum of the cross-sectional areas of the circular tubes 8 of the connecting portions 18 need to be approximately the same. Since the tube 8 is used, the circular tube 8 can be configured with a smaller diameter than the connection portion 18 formed by one or two circular tubes. Therefore, the space | interval of the flat heat exchanger tube 1 of a step direction (B direction) can be made small. For this reason, in the case of the same amount of heat exchange, the size can be reduced, and in the case of the same size, the number of stages of the flat heat transfer tube 1 can be increased to increase the amount of heat exchange.

In the example given in the first embodiment, when two circular pipes 8 are connected, one circular pipe 8 has an inner diameter of about 4.4 mm. However, as in the present embodiment, three circular pipes 8 are used. In this case, one circular tube 8 has an inner diameter of about 3.6 mm, and the step pitch P of the flat heat transfer tube 1 shown in FIG. For this reason, it is possible to further reduce the size or improve the heat exchange performance as compared with the first embodiment.
Further, the flat heat transfer tube connecting portion and the circular tube connecting portion of the connecting joint 13 can reduce the amount of deformation of the shape as compared with the connecting joint 11. For this reason, when the connection joint 13 is formed by a press or the like, it is difficult for thickness change, cracking, and the like to occur, and it is possible to prevent a failure rate and a decrease in pressure resistance, thereby improving corrosion resistance.

  Further, in FIG. 16, three U-shaped circular tubes 8 are connected, but the step pitch of the flat heat transfer tube 1 can be made shorter than that of the first embodiment, and the size can be further reduced. Or improvement in heat exchange performance. Further, the connection joint can be easily formed, and the reliability is improved.

  When the connection portion 18 is constituted by four or more circular tubes, the U-shaped circular tubes may be arranged in a line in the gas flow direction, but other arrangement methods are also possible. FIG. 17 is a perspective view showing an example of the connecting portion 18 according to the present embodiment when the four circular tubes 8 are configured. Instead of connecting the circular tubes 8 to be connected in the major axis direction of the cross section of the flat heat transfer tube 1, the connecting shape is such that the four circular tubes 8 form an annular bundle.

  In the first embodiment, the direction in which the flat heat transfer pipe flow paths 5 are aligned and the direction in which the circular pipes 8 are aligned are the same, and the refrigerant flowing through the flat heat transfer pipe flow paths 5 remains in the circular pipe 8 as it is. There is a high possibility that it will flow. On the other hand, when the circular pipes 8 are connected in an annular shape as shown in FIG. 17, the refrigerant flowing out from the flow channel 5 in the flat heat transfer pipe flows into the respective circular pipes 8 after the flow is disturbed and mixed. Therefore, the refrigerant that has flowed out of the flat heat transfer tube 1 can be distributed almost evenly to each circular tube 8, and the function of a distributor can be provided. In this case, since the connection joint of the flat heat transfer tube 1 and the distributor are integrated, there is no need to prepare a separate distributor, and there is an advantage that the installation space can be reduced.

  FIG. 18 is a perspective view showing another configuration example of the heat exchanger 20 according to the present embodiment. When the connecting portion 18 is constituted by the two U-shaped circular tubes 8 and the upper or lower flat heat transfer tube 1 is connected, the upstream and the downstream are crossed in the gas flow direction (D direction). Connected to. Thus, it becomes a structure which connects with the flow path 5 in the flat heat exchanger tube in a different position with respect to the direction (D direction) where gas distribute | circulates by making the circular pipe 8 cross | intersect.

  Since the flat heat transfer tube 1 is composed of a plurality of flat heat transfer tube flow paths 5 arranged in parallel in the air flow direction as shown in FIG. 4, when the heat exchanger 20 is used, the air flow The temperature difference between the air and the refrigerant differs between the windward side and the leeward side. For this reason, the state of the refrigerant flowing inside becomes uneven in the plurality of flat heat transfer tube flow paths 5. For example, when used as an evaporator, there is a temperature difference on the windward side and heat exchange is easier. That is, if the dryness of the refrigerant becomes higher than that on the leeward side and flows through the flat heat transfer tube 1 as it is, only the gas is produced and heat exchange is not performed. When used as a condenser, there is still a temperature difference on the windward side, and heat exchange is easier. That is, when the dryness of the refrigerant is lowered and flows through the flat heat transfer tube 1 as it is, only the liquid is formed and heat exchange is not performed. Therefore, the amount of heat exchange is reduced.

  Therefore, the flat heat transfer that flows from the flow path on the leeward side of the flat heat transfer tube 1 to the leeward side of the flat heat transfer tube 1 that flows next and the flow that flows from the flow path on the leeward side of the flat heat transfer tube 1 flows next. The circular pipe 8 of the connection part is connected so that it flows on the windward side of the heat pipe 1. As described above, when one end of the heat exchanger 20 is connected so that the U-shaped circular tubes 8 intersect each other, the refrigerant flowing in the heat exchanger 20 always flows into the one end of the heat exchanger 20. The refrigerant flow on the upper side and the leeward side are switched, and the state of the refrigerant in the flat heat transfer tube 1 becomes uniform throughout the heat exchanger 20. For this reason, the bias of the refrigerant | coolant state which flows into the flat heat exchanger tube 1 can be prevented, the fall of heat exchange efficiency can be prevented, and a heat exchanger with high heat exchange performance can be obtained.

  In addition, in the connection part 18, the refrigerant | coolant is replaced by the upstream and downstream of the distribution direction (D direction) of gas by crossing the several U-shaped circular pipe 8 and connecting the flat heat exchanger tube 1. FIG. Shed. For example, when the connecting portion 18 is constituted by three U-shaped circular pipes 8 as shown in FIG. 16, the most upstream and the most downstream U-shapes in the gas flow direction (D direction). If the circular tubes 8 are crossed and the central U-shaped circular tube 8 is connected to the center as it is, it is possible to prevent the refrigerant state flowing in the flat heat transfer tube 1 from being biased. In other words, when at least two of the plurality of circular tubes 8 intersect and connect to each other, it is possible to prevent the refrigerant state flowing in the flat heat transfer tube 1 from being biased.

  FIG. 19 is a perspective view showing a heat exchanger 20 of another configuration example according to the present embodiment. In the first embodiment, the flat heat transfer tube 1 is connected by a plurality of circular tubes 8 on one end side of the heat exchanger 20, for example, one end side where the inflow pipe 3 and the outflow pipe 4 are installed. In FIG. 19, a plurality of, for example, two circular tubes, are connected to the flat heat transfer tubes 1 in two stages on both ends of the heat exchanger 20. When connecting with a flat heat transfer tube 1a whose one end is U-shaped as shown in FIG. 1, the refrigerant flow path in the two-stage flat heat transfer tube 1 connected with the U-shaped flat heat transfer tube 1a is fixed. It is. On the other hand, in FIG. 19, the connection of the circular pipe 8 can be changed at both ends of the heat exchanger 20, and a refrigerant channel with a higher degree of freedom can be configured.

Of course, in either case of FIGS. 16 and 17, both ends of the heat exchanger 20 may be connected by three circular tubes or four circular tubes as shown in FIG. A refrigerant channel having a higher degree of freedom than that of only one end can be configured.
Also in the configuration of FIG. 18, both ends of the heat exchanger 20 may be circular tubes 8, and when connected to the upper stage or the lower stage, they may be connected so as to intersect the inflow direction (D direction) of the air flow. . In the configuration of FIG. 18, the upstream and downstream refrigerant circuits of the air flow are switched every two stages. However, when both ends intersect, the upstream and downstream refrigerant circuits of the air flow are switched for each stage. It becomes. For this reason, the temperature of the refrigerant that exchanges heat with the air flow can be made more uniform, and the heat exchange efficiency can be further improved.

  FIG. 20 is a cross-sectional view showing another configuration of the flat heat transfer tube 1 according to the present embodiment. The flat heat transfer tube 1 shown here has a wedge-shaped cross section. That is, the length in the minor axis direction is different at both ends in the major axis direction, here H <G. FIG. 21 is a longitudinal sectional view of a heat exchanger using the flat heat transfer tube 1 having the shape shown in FIG. The same reference numerals as those in FIGS. 4 and 5 indicate the same or corresponding parts.

  The heat exchanger 20 is configured by a wedge-shaped flat heat transfer tube 1 configured by a plurality of, for example, eight flow channels 5 in the flat heat transfer tube, and a shape in which the flat heat transfer tube 1 is inserted into the plate-like fins 2. ing.

By making the flat heat transfer tube 1 into such a wedge shape, it becomes easy to insert into the plate-like fin 2 from the direction of the arrow Q at the time of manufacture. If the wedge-shaped flat heat transfer tubes 1 are inserted into the plurality of plate-like fins 2 arranged from the short side, the insertion is easy. After the insertion, the collar 6 and the flat heat transfer tube 1 are brazed, joined with an adhesive or the like, or mechanically crimped.
Thus, by making the flat heat transfer tube 1 into a wedge shape, it is possible to obtain a heat exchanger that can be easily inserted into the plate-like fins 2 at the time of manufacture, and it is possible to prevent an increase in the defective product rate.
In FIG. 20, the upstream length G in the gas flow direction (D direction) is longer than the downstream length H in the wedge-shaped cross section of the flat heat transfer tube 1. It is not a thing and may be reversed.

  When the flat heat transfer tube 1 having a wedge-shaped cross section is used as described above, the cross-sectional areas of the plurality of refrigerant flow paths are different in the plurality of flat heat transfer pipe flow paths 5. For this reason, the temperature of the refrigerant | coolant which flows through each of the flow path 5 in a flat heat exchanger tube tends to become non-uniform | heterogenous. At this time, as shown in FIG. 18, when the circular pipe 8 is connected by the connecting portion 18, the connection is performed so as to intersect the leeward side and the leeward side of the gas flow direction (D direction), and the position where the refrigerant flows is switched. By doing so, the refrigerant state is made uniform in the heat exchanger 20 as a whole, which is more effective.

  As described above, in the present embodiment, another configuration of the circular pipe of the connecting portion 18 has been described. However, as in the first embodiment, the gas flows between each other in parallel with a predetermined interval therebetween. A plurality of plate-like fins 2, and these plate-like fins 2 are provided so as to penetrate the plate-like fins 2 in the parallel direction (A direction). A plurality of refrigerant channels 5 arranged in the flow direction (D direction) through which the gas flows by a plurality of partition walls 47 extending in the direction), and the parallel direction (A direction) of the plate-like fins 2 and the gas flow direction (D direction). ) Each of the flat heat transfer tubes 1 formed in a plurality of stages in a direction (B direction) orthogonal to each of the above and a connection portion 18 that connects two ends of the flat heat transfer tubes 1 formed in a plurality of stages. The heat pipe 1 is opposed in a direction (B direction) in which the flat surfaces form a plurality of steps. The connecting portion 18 has a plurality of U-shaped circular tubes 8 arranged in the gas flow direction (D direction), and the two-stage flat heat transfer tubes are arranged via the circular tubes 8. 1 is connected, the flow of the refrigerant in the heat exchanger 20 can be freely set without being limited by the configuration of the header, the interval between the flat heat transfer tubes 1 in the step direction can be reduced, and the same heat exchange In the case of an amount, the size can be reduced, and in the case of a similar size, there is an effect that a heat exchanger that can increase the amount of heat exchange can be obtained.

  In addition, since the sum of the cross-sectional areas of the flow channels 5 in the flat heat transfer tubes and the sum of the cross-sectional areas of the plurality of circular tubes 8 are approximately the same, an increase in pressure loss can be prevented, and heat exchange efficiency can be prevented. There is an effect that a good heat exchanger can be obtained.

  In addition, as shown in FIG. 17, a connection joint having a circular tube connection portion that connects each of the plurality of circular tubes 8 at one end and a flat heat transfer tube connection portion that connects the flat heat transfer tube 1 to the other end. By connecting the flat heat transfer tube 1 and each of the plurality of circular tubes 8 with the connection joint 14, the connection can be facilitated when connecting the end portions of the flat heat transfer tube 1. Furthermore, the diameter of one circular pipe 8 can be reduced, the deformation amount of the shape of the connection joint 14 can be reduced, an increase in defective products and a decrease in pressure resistance can be prevented, and the highly reliable connection portion 18 is provided. There is an effect that a heat exchanger can be realized.

  Further, the two-stage flat heat transfer tubes 1 are connected by being intersected by a plurality of circular tubes 8 so as to be connected to the flow channels 5 in the flat heat transfer tubes at different positions with respect to the direction in which the gas flows (D direction). By comprising, the freedom degree of the refrigerant | coolant flow path structure in the heat exchanger 20 can be improved, and also the refrigerant | coolant state which flows through the heat exchanger 20 can be equalize | homogenized, and heat exchange efficiency can be improved.

Embodiment 3 FIG.
In Embodiment 3 of the present invention, a connection joint will be described. FIG. 22 is an explanatory view showing a cross section of the connecting portion 18 including the connecting joint 15 according to Embodiment 3 of the present invention. 11C actually shows a cross section along the central vertical line in FIG. 11C, with one end connected to the flat heat transfer tube 1 15a and the other end connected to a plurality of, for example, two circular tubes 8, respectively. It has the connection part 15b. Here, the flat heat transfer tube 1 is assumed to have four flow channels 5 in the flat heat transfer tube. J1 and J2 indicate the flow direction of the refrigerant.

As shown in FIG. 22, inside the connection joint 15, a predetermined space 16 is provided between the connection end 1 b of the flat heat transfer tube 1 and the connection ends 8 b of the plurality of circular tubes 8, and the flat heat transfer tube 1 A plurality of circular tubes 8 are connected. The refrigerant flows through the two circular tubes 8 in the direction of the solid arrow J1 and flows into the space 16. The refrigerant is mixed with the flow disturbed in the space 16 and flows substantially evenly into each of the plurality of flat heat transfer tube channels 5 provided in the flat heat transfer tube 1.
Conversely, when the refrigerant flows in the direction of the broken line arrow J <b> 2, the refrigerant flowing through the plurality of flat heat transfer tube flow paths 5 of the flat heat transfer tube 1 flows into the space 16. The refrigerant is mixed with the flow disturbed in the space 16 and flows almost evenly into the two circular tubes 8.

  In this way, by providing the space 16 between the circular tube 8 and the flat heat transfer tube 1 in the connection joint 15, the refrigerant flowing through the plurality of flat heat transfer tube flow paths 5 or the circular tubes 8 is contained in the connection joint 15. Mixed in. The space 16 has a predetermined width L between the connection end 1b of the flat heat transfer tube 1 and the connection ends 8b of the plurality of circular tubes 8 in the refrigerant flow directions J1 and J2. For example, the width L is configured to be equal to or larger than the outer diameter of the connected circular tube 8. The width L of the space 16 has an optimum value depending on the speed, flow rate, and the like of the refrigerant flowing inside, but it is sufficient that the refrigerant is mixed to some extent.

  As described in the configuration crossing the circular tubes 8 in FIG. 18, the temperature difference between the air and the refrigerant flowing through the flat heat transfer tube flow path 5 differs between the windward side and the leeward side in the air flow direction. While the refrigerant flows from the inflow pipe 3 to the outflow pipe 4, for example, the refrigerant that flows on the leeward side flows directly on the leeward side, and the refrigerant that flows on the leeward side remains fixed on the leeward side. The refrigerant state becomes uneven between the two sides and the heat exchange efficiency decreases. In the configuration of FIG. 22, a space 16 is provided between the connection end 1 b of the flat heat transfer tube 1 and the connection end 8 b of the circular tube 8, and the refrigerant on the windward side and the leeward side is mixed in this space 16. The refrigerant state can be made uniform, and a decrease in heat exchange efficiency can be prevented.

  FIG. 23 is a graph showing changes in air temperature and refrigerant temperature in the heat exchanger 20 when the heat exchanger 20 is used as an evaporator, and FIG. 24 uses the heat exchanger 20 as a condenser. It is a graph which shows the change of the air temperature and refrigerant | coolant temperature in the heat exchanger 20 in a case. 23 and 24, the horizontal axis indicates the position from the inlet to the outlet of the heat exchanger, and the vertical axis indicates the temperature. FIG. 23A and FIG. 24A show the case where the refrigerant flows in the same refrigerant flow path with respect to the air flow, the refrigerant flowing on the leeward side always flows on the leeward side, and the refrigerant flowing on the leeward side always flows on the leeward side. It is a graph of. In the figure, the dotted line curve shows the change in air temperature, the solid line curve is the flat rear hole refrigerant temperature, and the one-point difference curve is the flat tube front hole refrigerant temperature. Here, the flat tube front hole is the flow channel 5 in the flat heat transfer tube upstream of the gas flow direction (D direction), and the flat tube rear hole is the flat flow downstream of the air flow. This is the heat pipe flow path 5. As shown in FIG. 23 (a), when the heat exchanger 20 is operated as an evaporator, heat is easily exchanged in the flat tube front hole, so that the flat tube front hole refrigerant temperature flows to the heat exchanger outlet. The temperature difference from the air temperature becomes small. On the other hand, in the flat tube rear hole, the temperature difference between the refrigerant and the air temperature gradually decreases. This phenomenon is the same when the condenser is operated as shown in FIG. Such non-uniformity of the refrigerant state causes a decrease in heat exchange efficiency.

  In the present embodiment, the refrigerant in the plurality of flow paths is mixed in the space 16 in the flat heat transfer tube 1 and flows again into the flat heat transfer tube 1. For example, in the configuration of FIG. 1, connection joints are provided at both ends of the U-shaped circular tube 8. That is, if the connection joint 15 according to the present embodiment is used, the refrigerant from the flat heat transfer tube 1 is mixed in the space 16, flows through the U-shaped circular tube 8, and is mixed again in the space 16 to be flattened heat transfer tube 1. to go into. For this reason, the refrigerant | coolant of a substantially uniform state flows into the flow path 5 in each flat heat exchanger tube of the flat heat exchanger tube 1, and it can prevent the heat exchange efficiency fall.

  FIGS. 23B and 24B show how the air temperature and the refrigerant temperature change in the heat exchanger 20 when the connection joint 15 according to the present embodiment is used. FIG. 23 (b) shows the operation as an evaporator, and FIG. 24 (b) shows the operation as a condenser. While flowing through the flat heat transfer tube 1, the temperature difference between the flat tube front hole refrigerant temperature and the air temperature becomes small. Then, it flows into the connection joint 15 at the connection portion 18 of the flat heat transfer tube 1. In the portion (S) of the connection joint 15, the flat tube front hole refrigerant and the flat tube rear hole refrigerant are mixed. Therefore, at any position from the heat exchanger inlet to the heat exchanger outlet, the difference between the air temperature and the refrigerant temperature can be kept to some extent in both the flat tube front hole and the flat tube rear hole, and the heat exchange efficiency Can be prevented from decreasing. This is the same both when operating as an evaporator (FIG. 23 (b)) and when operating as a condenser (FIG. 24 (b)).

  Thus, by using the connection joint 15 of the present embodiment for the heat exchanger 20 shown in FIGS. 1 and 16, a heat exchanger with high heat exchange efficiency can be obtained. Moreover, if the connection joint 15 is used for the heat exchanger 20 having the configuration shown in FIGS. 17 and 18, the effect of mixing the refrigerant is increased, and a heat exchanger with higher heat exchange efficiency can be obtained. Further, when the heat exchanger 20 has a width in the A direction and the length of the one-stage flat heat transfer tube 1 in the A direction becomes long, as shown in FIG. 19, the inflow pipe 3 and the inflow pipe 4. What is necessary is just to connect with the multiple U-shaped circular pipes 8 using the connection joint 15 also to the edge part side opposite to the edge part side which provided. In this way, since the refrigerant is mixed at both ends of the flat heat transfer tube 1, a heat exchanger having higher heat exchange efficiency can be obtained.

  The connection joint 15 shown in FIG. 22 has a configuration in which refrigerant is mixed in the space 16. On the other hand, the connection part 18 of the structure in which a refrigerant | coolant is not mixed within a connection joint is shown in FIG. FIG. 25 is an explanatory diagram illustrating a cross section of the connection portion 18 including the connection joint 17 according to the third embodiment of the present invention. 11C actually shows a cross section along the central vertical line in FIG. 11C. One end portion has a connection portion 17a to the flat heat transfer tube 1, and the other end portion has a connection portion 17b to each of the plurality of circular tubes 8. In the connection joint 17, the connection end 1 b of the flat heat transfer tube 1 and the connection ends 8 b of the plurality of circular tubes 8 are abutted to connect the flat heat transfer tube 1 to a plurality of, for example, two circular tubes 8. To do. Here, the flat heat transfer tube 1 is assumed to have four flow channels 5 in the flat heat transfer tube.

  Inside the connection joint 17, the connection end 1 b of the flat heat transfer tube 1 and the connection end 8 b of the circular tube 8 are in contact with each other. Therefore, the refrigerant that has flowed from the circular tube 8 in the direction of the solid arrow J1 flows into the flat heat transfer tube flow path 5 of the flat heat transfer tube 1 as it is without being mixed. Conversely, when the refrigerant flows from the plurality of flat heat transfer tube flow paths 5 provided in the flat heat transfer tube 1 in the direction of the broken arrow J2, it flows to the circular tube 8 as it is. When the heat exchanger 20 having the configuration of FIG. 1 is connected by the connection joint 17, as shown in FIGS. 23 (a) and 24 (a), the difference between the refrigerant temperature of the flat heat transfer tube front hole and the air temperature is small. Thus, the heat exchange efficiency is likely to decrease. However, when the heat exchanger 20 having the configuration shown in FIG. 18 is connected by the connection joint 17, the refrigerant is not mixed in the connection joint 17, so that the refrigerant state is controlled only in accordance with the connection method of the U-shaped circular tube 8. It will be.

  In the configuration of FIG. 18, a U-shaped circular tube 8 is connected so that the refrigerant flowing from the flow path on the windward side of the flat heat transfer tube 1 flows to the leeward side of the flat heat transfer tube 1 that flows next. A U-shaped circular tube 8 is connected so as to flow the refrigerant flowing from the leeward flow channel to the windward side of the flat heat transfer tube 1 that flows next. In this way, the connection of the flat heat transfer tubes 1 is crossed, so that the flow of the refrigerant on the windward side and the leeward side in the gas flow direction (D direction) is always switched, or the flatness of each stage in the heat exchanger 20 The connection joint 17 is effective when a desired refrigerant flow path is positively configured in consideration of the flow of the refrigerant state in the refrigerant pipe, such as by changing the connection method of the heat transfer tubes 1. By using the connection joint 17 in which the refrigerant flows inside as it is, there is an effect that a desired refrigerant flow path can be configured and the refrigerant flow can be easily controlled.

  22 and 25, the flat heat transfer tube 1 has four flat heat transfer tube flow paths 5, but the present invention is not limited to this. A configuration having more than four flat heat transfer tube flow paths 5 may be used, or three or less. On the other hand, the number of U-shaped circular tubes 8 is not limited to two.

As described above, in this embodiment, the flat heat transfer tube connection portion having the circular tube connection portions 15b and 17b connecting the plurality of circular tubes 8 at one end portion and connecting the flat heat transfer tube 1 to the other end portion. Since the connection joints 15 and 17 having 15a and 17a are provided and the flat heat transfer tubes 1 and the plurality of circular tubes 8 are connected by the connection joints 15 and 17, it is easy to manufacture and can easily cope with the change of the refrigerant flow path. A heat exchanger with the configuration is obtained.
Here, the connection joints 15 and 17 are formed, and the flat heat transfer tube 1 and the connection joints 15 and 17 and the connection joints 15 and 17 and the circular tube 8 are fixed by brazing or the like.
In the configuration in which the connection end 1b of the flat heat transfer tube 1 and the connection ends 8b of the plurality of circular tubes 8 are abutted as shown in FIG. 25, the connection joint 17 is not provided separately, and the connection end of the flat heat transfer tube 1 is provided. It is also possible to mold integrally with 1b. For example, the end portion of the flat heat transfer tube 1 is expanded so that the partition wall at the end portion is not provided with a predetermined width in the flow direction of the refrigerant, and a plurality of circular tubes 8 are provided in the portion where the partition wall is eliminated. It may be inserted and fixed so that the connection end 8b of the circular tube 8 is abutted against the partition wall inside the flat heat transfer tube 1.

  In addition, according to the present embodiment, a space 16 having a predetermined width L in the direction in which the refrigerant flows is formed between the connection end 1b of the flat heat transfer tube 1 and the connection ends 8b of the plurality of circular tubes 8. As a result, the refrigerant flowing in from the plurality of circular tubes 8 is mixed in the space 16 and flows almost uniformly into the respective flow paths 5 of the flat heat transfer tube 1. On the contrary, the refrigerant flowing out from each flow path 5 of the flat heat transfer tube 1 is mixed in the space 16, and the refrigerant flows almost evenly into the plurality of circular tubes 8 connected to the connection joint 15. Thereby, a refrigerant | coolant state can be equalize | homogenized by the flow direction (D direction) of the gas of the flat heat exchanger tube 1, and heat exchange efficiency can be made high.

  Further, the connection end 1 b of the flat heat transfer tube 1 and the connection ends 8 b of the plurality of circular tubes 8 are abutted to connect the flat heat transfer tube 1 and the plurality of circular tubes 8, so that the flat heat transfer tube 1 There is an effect that it is possible to easily control the refrigerant flowing for each of the plurality of flow channels 5 in the flat heat transfer tube.

  In any of Embodiments 1 to 3, this is a case of two paths with two flow paths in one heat exchanger. For example, the upper half and the lower half are configured by one path. Two rows of heat exchangers are stacked in the C direction. The present invention is not limited to this, and may be configured with one pass or three or more passes. Moreover, you may comprise in 1 direction in a C direction, or 3 or more rows.

  In any of the first to third embodiments, the connection portion connecting the flat heat transfer tubes 1 uses a circular tube 8 bent in a U shape and connects nearby flat heat transfer tubes. is there. For example, depending on the refrigerant flow path to be formed, flat heat transfer tubes that are separated from each other may be connected, and at this time, both ends are short and a U-shaped circular tube having a long central portion is formed.

  By using the heat exchanger 20 described in the first to third embodiments for an evaporator or a condenser of a refrigeration cycle apparatus such as an air conditioner or a refrigerator with a circuit configuration as shown in FIG. A refrigeration cycle apparatus having a heat exchanger capable of increasing the amount of heat exchange, having high reliability, capable of being downsized, and having good heat exchange performance can be obtained.

Moreover, the refrigerant used for the refrigeration cycle apparatus is not particularly limited, and any refrigerant may be used. For example, when a single HC refrigerant or a mixed refrigerant containing HC, R32, ammonia, carbon dioxide, or the like is used, a device with a small global warming potential can be realized. Further, when a refrigerant that radiates heat in a supercritical state is used, for example, in the case of cooling operation, the outdoor heat exchanger 33 shown in FIG. 2 operates as a radiator instead of a condenser.
Moreover, although the gas which heat-exchanges with a refrigerant | coolant was made into air, for example, it is not restricted to this, Other gas may be sufficient.

DESCRIPTION OF SYMBOLS 1 Flat heat transfer pipe 2 Plate-shaped fin 3 Inflow piping 4 Outflow piping 5 Flow path in flat heat transfer pipe 8 U-shaped circular pipe 9 Connection joint 15 Connection joint 16 Space 17 Connection joint 18 Connection part 31 Compressor 33 Heat exchanger 34 Restriction Device 47 Bulkhead A Parallel direction of plate fins B Stage direction C Row direction D Gas flow direction J1, J2 Refrigerant flow direction

Claims (3)

A plurality of plate-like fins that are arranged in parallel with each other at a predetermined interval and in which gas flows between the individual,
It provided these plate-shaped fins so as to penetrate in parallel direction of the plate-like fin cross section with a flat shape, forming a plurality of stages in a direction perpendicular to the respective flow direction of the parallel direction and the gas of the plate-like fin Flat heat transfer tubes,
A connecting portion that connects two end portions of the flat heat transfer tubes forming the plurality of stages at one end side of the heat exchanger ;
The flat heat transfer tube is
The flat surfaces are arranged so as to face each other in the direction of forming the plurality of steps , and are provided in the gas line in the gas flow direction by a plurality of partition walls extending in the parallel direction of the plate-like fins. Have four or more flat heat transfer tube flow channels,
The connecting portion is
Two or three U-shaped circular tubes arranged in the gas flow direction, and connection joints provided at both ends of the circular tubes for connecting the flat heat transfer tubes and the circular tubes, respectively. has, in the degree sum the flow path cross-sectional area of the circular tube and the sum of the cross-sectional area of the flattened heat transfer pipe passage, a configuration of connecting the flat heat transfer tubes 2 stages via the circular tube And
The connecting joint is
There is a circular tube connection part that joins each of the two or three circular tubes by brazing at one end, and a flat heat transfer tube connection part that joins the flat heat transfer tube by brazing at the other end. In the connection joint, the refrigerant flows between the connection end of the circular tube connected to the circular tube connection portion and the connection end of the flat heat transfer tube connected to the flat heat transfer tube connection portion. A heat exchanger characterized in that a space having a width equal to or larger than the outer diameter of the circular pipe is formed in the direction . When there are two circular pipes in the connection part, the two circular pipes intersect the gas flow direction, and when there are three circular pipes in the connection part, the gas flow direction. 2. The heat exchanger according to claim 1, wherein a circular pipe on the most upstream side and a circular pipe on the most downstream side intersect the gas flow direction, and the central pipe is connected at the center as it is. At least a compressor, a condenser, a throttling device, and an evaporator are sequentially connected by piping to circulate the refrigerant, and the heat exchanger according to claim 1 or 2 is used as the evaporator or the condenser. A refrigeration cycle apparatus.

Images