JP7799178B2 - Heat exchanger and air conditioning device - Google Patents

Description

Related to heat exchangers and air conditioning equipment.

A heat exchanger having a cylindrical header to which multiple heat transfer tubes are connected is known.

Patent Document 1 (JP 2016-125748 A) discloses a heat exchanger equipped with a header (header manifold) that extends vertically and has one end of multiple heat transfer tubes (flat tubes) connected to it.

The header of the heat exchanger in Patent Document 1 has a partition member that separates the internal space into a first space connected to a heat transfer tube and a second space to which no heat transfer tube is connected. The partition member has two communication passages formed in the header at positions a predetermined distance apart in the longitudinal direction of the header, connecting the first space with the second space. This creates a loop structure inside the header, and the refrigerant that flows into the header flows from one end of the header to the other within the first space, and then flows from the other end of the header to the first end within the second space. This promotes mixing of the liquid-phase refrigerant and gas-phase refrigerant flowing through the header.

Furthermore, the header of the heat exchanger in Patent Document 1 is provided with a nozzle that generates an upward flow within the first space when the heat exchanger functions as an evaporator. This increases the flow rate of the refrigerant flowing into the first space from the inlet, ensuring a sufficient supply of refrigerant to the heat transfer tubes connected at a position away from the inlet.

However, even with such a header, if the quality of the refrigerant flowing in is high, an imbalance in the pressure distribution can occur inside, causing a bias in the distribution of liquid and gas phase refrigerant among the multiple connected heat transfer tubes, resulting in a drift.

The purpose of this disclosure is to provide a heat exchanger and air conditioning device that suppresses the occurrence of uneven flow in heat transfer tubes.

A heat exchanger according to a first aspect is a heat exchanger comprising a plurality of heat transfer tubes and a cylindrical header. The header has a refrigerant flow path formed therein, connected to the plurality of heat transfer tubes. The refrigerant flow path has a first flow path, a first communication port, and a second flow path. The first flow path extends from an inlet through which the refrigerant flows toward a first end of the header along a first direction, which is the longitudinal direction of the header. The first communication port communicates with the end of the first flow path opposite the inlet. The second flow path communicates with the first communication port, and extends from the first communication port along the first direction toward a second end of the header.

The heat transfer tubes are connected to a first flow path so as to intersect in a first direction. The first flow path has a different flow path cross-sectional area at a first position than at a second position, which is a predetermined distance away from the first position toward the first end of the header.

With this heat exchanger, by making the flow path area of the first flow path at the first position different from the flow path cross-sectional area at the second position, the first flow path can be shaped to suppress imbalances in pressure distribution. Therefore, with this heat exchanger, the occurrence of uneven flow in the heat transfer tubes is suppressed.

A heat exchanger according to a second aspect is the heat exchanger according to the first aspect, wherein the first position is near the inlet.

A heat exchanger according to a third aspect is a heat exchanger according to the first or second aspect, wherein the second flow path has a second communication port that communicates with the first flow path at an end opposite the first communication port. Refrigerant that flows into the first flow path from the inlet flows into the second flow path from the first communication port, and then flows into the first flow path through the second communication port.

This heat exchanger loops the refrigerant through the first flow path, the first communication port, the second flow path, and the second communication port, eliminating imbalances in pressure distribution in the first flow path.

The heat exchanger according to the fourth aspect is any one of the heat exchangers according to the first aspect to the third aspect, in which the flow path cross-sectional area increases from the first position to the second position.

This heat exchanger promotes the upward movement of refrigerant flowing in from the inlet through the first flow path, eliminating imbalances in pressure distribution in the first flow path.

A heat exchanger according to a fifth aspect is the heat exchanger according to the fourth aspect, wherein the second position is located in the center in the first direction. The flow path cross-sectional area decreases from the second position toward the first end of the header.

This heat exchanger promotes the movement of refrigerant flowing in from the inlet toward the center of the first flow path, eliminating imbalances in pressure distribution in the first flow path.

A heat exchanger according to a sixth aspect is a heat exchanger according to the fourth or fifth aspect, in which the shape of the flow path cross section of the first flow path changes in a direction perpendicular to the longitudinal direction of the heat transfer tube as viewed from the extension direction of the first flow path as it moves from the first position toward the first end side of the header.

A heat exchanger according to a seventh aspect is any of the heat exchangers according to the fourth to sixth aspects, in which the shape of the flow path cross section of the first flow path changes in the longitudinal direction of the heat transfer tube as viewed from the extension direction of the first flow path as it moves from the first position toward the first end side of the header.

The heat exchanger according to the eighth aspect is any one of the heat exchangers according to the first to seventh aspects, in which the longitudinal direction of the header coincides with the vertical direction.

An air conditioning apparatus according to a ninth aspect includes a refrigerant circuit including any of the heat exchangers according to the first to eighth aspects, and operates so that the quality fraction of the refrigerant at the inlet of the heat exchanger is 0.25 or higher.

An air conditioning apparatus according to a tenth aspect comprises a refrigerant circuit including any of the heat exchangers according to the first to eighth aspects, and the refrigerant circuit is filled with a single refrigerant consisting of any of propane, _CO2 , and isobutane, or a mixed refrigerant including any of propane, _CO2 , and isobutane.

In a refrigerant circuit filled with a natural refrigerant such as propane, _CO2 , or isobutane, the quality of the refrigerant at the inlet of the heat exchanger is high, and uneven flow in the heat transfer tubes is likely to occur. However, with the air conditioner equipped with the above-mentioned heat exchanger, uneven flow in the heat transfer tubes is suppressed even when using natural refrigerants such as propane, _CO2 , or isobutane.

1 is a schematic configuration diagram of an air conditioning device 1. FIG. FIG. 2 is a schematic perspective view of the outdoor heat exchanger 11. 2 is a partially enlarged view of a heat exchange section 27 of the outdoor heat exchanger 11. FIG. 4 is a schematic diagram showing the state in which fins 29 are attached to flat tubes 28 in a heat exchange section 27. FIG. 3 is an explanatory diagram showing the state of refrigerant flow in the outdoor heat exchanger 11 functioning as a refrigerant evaporator. FIG. 10 is a side view showing the external configuration of branched liquid refrigerant connection pipes 49a to 49e connected to a liquid header 300. FIG. FIG. 2 is an exploded perspective view of a portion near the upper end of the liquid header 30. FIG. 2 is a cross-sectional plan view of the liquid header 30. 10 is a cross-sectional plan view showing how branched liquid refrigerant connection pipes 49a to 49e and flat tubes 28 are connected to a liquid header 30. FIG. FIG. 2 is a cross-sectional perspective view of a portion near the upper end of the liquid header 30. FIG. 2 is a schematic view of the first liquid side member 31 as seen from the rear side. FIG. 2 is a schematic view of the second liquid side member 32 as seen from the rear side. FIG. 10 is a schematic view of the third liquid side member 33 as seen from the rear side. FIG. 10 is a schematic view of a fourth liquid side member 34 as seen from the rear side. FIG. 10 is a schematic view of the fifth liquid side member 35 as seen from the rear side. FIG. 10 is a schematic view of the sixth liquid side member 36 as seen from the rear side. FIG. 10 is a schematic view of the seventh liquid side member 37 as seen from the rear side. 10 is a cross-sectional view of the periphery of an upflow space 34z of the outdoor heat exchanger 11 according to Modification 1A, as viewed from the right side. FIG. FIG. 10 is an exploded perspective view of a portion near the upper end of a liquid header 30 of an outdoor heat exchanger according to a second embodiment. 10 is a schematic view of a fourth liquid side member 38 of a liquid header 30 of an outdoor heat exchanger according to a second embodiment, viewed from the rear side. FIG. FIG. 10 is a cross-sectional view of the periphery of an upflow space 34z1 of an outdoor heat exchanger according to Modification 2A, as viewed from the right side.

First Embodiment
(1) Configuration of the Air Conditioning Apparatus An air conditioning apparatus 1 including a heat exchanger according to a first embodiment of the present disclosure will be described with reference to the drawings.

Figure 1 is a schematic diagram of the air conditioning unit 1.

The air conditioning device 1 is a device that performs cooling and heating operations in a space to be air-conditioned by using a vapor compression refrigeration cycle. The space to be air-conditioned is, for example, a space within a building such as an office building, commercial facility, or residence. Note that an air conditioning device is merely one example of a refrigerant cycle device, and the heat exchanger disclosed herein may also be used in other refrigerant cycle devices, such as refrigerators, freezers, water heaters, and floor heating systems.

As shown in Figure 1, the air conditioning system 1 primarily comprises an outdoor unit 2, an indoor unit 9, a liquid refrigerant connection pipe 4, a gas refrigerant connection pipe 5, and a control unit 3 that controls the equipment that makes up the outdoor unit 2 and the indoor unit 9. The liquid refrigerant connection pipe 4 and the gas refrigerant connection pipe 5 are refrigerant connection pipes that connect the outdoor unit 2 and the indoor unit 9. In the air conditioning system 1, the outdoor unit 2 and the indoor unit 9 are connected via the liquid refrigerant connection pipe 4 and the gas refrigerant connection pipe 5 to form a refrigerant circuit 6.

The refrigerant filled in the refrigerant circuit 6 is a well-known refrigerant such as an HFC refrigerant, an HFO refrigerant, or a natural refrigerant. Natural refrigerants such as propane, CO ₂ , and isobutane, which tend to have a high dryness, are also suitable for use, as will be described in detail later. These natural refrigerants may be used as a single refrigerant or as a mixed refrigerant.

In Figure 1, the air conditioning apparatus 1 has one indoor unit 9, but the air conditioning apparatus 1 may have multiple indoor units 9 connected in parallel to the outdoor unit 2 by liquid refrigerant connection pipes 4 and gas refrigerant connection pipes 5. The air conditioning apparatus 1 may also have multiple outdoor units 2. The air conditioning apparatus 1 may also be an integrated air conditioning apparatus in which the outdoor unit 2 and the indoor unit 9 are formed integrally.

(1-1) Outdoor Unit The outdoor unit 2 is installed outside the space to be air-conditioned, for example, on the roof of a building or near a wall of a building.

The outdoor unit 2 mainly includes an accumulator 7, a compressor 8, a four-way switching valve 10, an outdoor heat exchanger 11 (an example of a heat exchanger), an expansion mechanism 12, a liquid-side shut-off valve 13, a gas-side shut-off valve 14, and an outdoor fan 16.

The outdoor unit 2 mainly has refrigerant pipes connecting the various devices that make up the refrigerant circuit 6: a suction pipe 17, a discharge pipe 18, a first gas refrigerant pipe 19, a liquid refrigerant pipe 20, and a second gas refrigerant pipe 21. The suction pipe 17 connects the four-way switching valve 10 to the suction side of the compressor 8. The suction pipe 17 is provided with an accumulator 7. The discharge pipe 18 connects the discharge side of the compressor 8 to the four-way switching valve 10. The first gas refrigerant pipe 19 connects the four-way switching valve 10 to the gas side of the outdoor heat exchanger 11. The liquid refrigerant pipe 20 connects the liquid side of the outdoor heat exchanger 11 to the liquid-side shut-off valve 13. The liquid refrigerant pipe 20 is provided with an expansion mechanism 12. The second gas refrigerant pipe 21 connects the four-way switching valve 10 to the gas-side shut-off valve 14.

The compressor 8 is a device that draws in low-pressure refrigerant in the refrigeration cycle through the suction pipe 17, compresses the refrigerant using a compression mechanism (not shown), and discharges the compressed refrigerant into the discharge pipe 18.

The four-way switching valve 10 is a mechanism that switches the refrigerant flow direction to change the state of the refrigerant circuit 6 between cooling operation and heating operation. When the refrigerant circuit 6 is in cooling operation, the outdoor heat exchanger 11 functions as a refrigerant radiator (condenser), and the indoor heat exchanger 91 functions as a refrigerant evaporator. When the refrigerant circuit 6 is in heating operation, the outdoor heat exchanger 11 functions as a refrigerant evaporator, and the indoor heat exchanger 91 functions as a refrigerant condenser. When the four-way switching valve 10 switches the refrigerant circuit 6 to cooling operation, the four-way switching valve 10 connects the suction pipe 17 to the second gas refrigerant pipe 21 and the discharge pipe 18 to the first gas refrigerant pipe 19 (see the solid lines within the four-way switching valve 10 in Figure 1). When the four-way switching valve 10 sets the refrigerant circuit 6 in heating operation, the four-way switching valve 10 connects the suction pipe 17 to the first gas refrigerant pipe 19 and the discharge pipe 18 to the second gas refrigerant pipe 21 (see the dashed lines within the four-way switching valve 10 in Figure 1).

The outdoor heat exchanger 11 (an example of a heat exchanger) is a device that performs heat exchange between the refrigerant flowing inside and the air (heat source air) in the location where the outdoor unit 2 is installed. Details of the outdoor heat exchanger 11 will be described later.

The expansion mechanism 12 is disposed in the refrigerant circuit 6 between the outdoor heat exchanger 11 and the indoor heat exchanger 91. In this embodiment, the expansion mechanism 12 is disposed in the liquid refrigerant pipe 20 between the outdoor heat exchanger 11 and the liquid-side shut-off valve 13. In this air conditioning device 1, the expansion mechanism 12 is provided in the outdoor unit 2, but the expansion mechanism 12 may alternatively be provided in the indoor unit 9, which will be described later. The expansion mechanism 12 adjusts the pressure and flow rate of the refrigerant flowing through the liquid refrigerant pipe 20. In this embodiment, the expansion mechanism 12 is an electronic expansion valve with a variable opening, but the expansion mechanism 12 may also be a temperature-sensing bulb-type expansion valve or a capillary tube.

The accumulator 7 is a container with a gas-liquid separation function that separates the incoming refrigerant into gas refrigerant and liquid refrigerant. The accumulator 7 also has a storage function for excess refrigerant that occurs in response to fluctuations in operating load, etc.

The liquid-side shut-off valve 13 is a valve provided at the connection between the liquid refrigerant pipe 20 and the liquid refrigerant communication pipe 4. The gas-side shut-off valve 14 is a valve provided at the connection between the second gas refrigerant pipe 21 and the gas refrigerant communication pipe 5. The liquid-side shut-off valve 13 and the gas-side shut-off valve 14 are open when the air conditioning unit 1 is operating.

The outdoor fan 16 is a fan that draws external heat source air into the casing of the outdoor unit 2 (not shown), supplies it to the outdoor heat exchanger 11, and discharges the air that has exchanged heat with the refrigerant in the outdoor heat exchanger 11 out of the casing of the outdoor unit 2. The outdoor fan 16 is, for example, a propeller fan.

(1-2) Indoor Unit The indoor unit 9 is a unit installed in the space to be air-conditioned. The indoor unit 9 is, for example, a ceiling-mounted unit, but may also be a ceiling-suspended, wall-mounted, or floor-standing unit. The indoor unit 9 may also be installed outside the space to be air-conditioned. For example, the indoor unit 9 may be installed in an attic, a machine room, a garage, or the like. In this case, an air passage is installed that supplies air that has exchanged heat with the refrigerant in the indoor heat exchanger 91 from the indoor unit 9 to the space to be air-conditioned. The air passage is, for example, a duct.

The indoor unit 9 mainly includes an indoor heat exchanger 91 and an indoor fan 92.

In the indoor heat exchanger 91, heat is exchanged between the refrigerant flowing through the indoor heat exchanger 91 and the air in the space to be air-conditioned. The indoor heat exchanger 91 may be, for example, a fin-and-tube heat exchanger having multiple heat transfer tubes and fins (not shown), although this type is not limited thereto. One end of the indoor heat exchanger 91 is connected to the liquid refrigerant connection pipe 4 via a refrigerant pipe. The other end of the indoor heat exchanger 91 is connected to the gas refrigerant connection pipe 5 via a refrigerant pipe.

The indoor fan 92 is a mechanism that draws air from the space to be air-conditioned into the casing (not shown) of the indoor unit 9, supplies it to the indoor heat exchanger 91, and blows the air that has exchanged heat with the refrigerant in the indoor heat exchanger 91 into the space to be air-conditioned. The indoor fan 92 is, for example, a turbofan. However, the type of indoor fan 92 is not limited to a turbofan and may be selected as appropriate.

(1-3) Control Unit The control unit 3 is a functional unit that controls the operations of the various devices that make up the air conditioning apparatus 1.

The control unit 3 is configured, for example, by connecting an outdoor control unit (not shown) of the outdoor unit 2 and an indoor control unit (not shown) of the indoor unit 9 so that they can communicate with each other via a transmission line (not shown). The outdoor control unit and the indoor control unit are units that include, for example, a microcomputer and memory that stores various programs for controlling the air conditioning apparatus 1 that can be executed by the microcomputer. For convenience, the control unit 3 is depicted in Figure 1 at a location separate from the outdoor unit 2 and the indoor unit 9.

Note that the functions of the control unit 3 do not have to be realized by cooperation between the outdoor control unit and the indoor control unit. For example, the functions of the control unit 3 may be realized by either the outdoor control unit or the indoor control unit, or some or all of the functions of the control unit 3 may be realized by a control device (not shown) that is separate from the outdoor control unit and the indoor control unit.

As shown in FIG. 1, the control unit 3 is electrically connected to various devices in the outdoor unit 2 and the indoor unit 9, including the compressor 8, four-way switching valve 10, expansion mechanism 12, outdoor fan 16, and indoor fan 92. The control unit 3 is also electrically connected to various sensors (not shown) provided in the outdoor unit 2 and the indoor unit 9. The control unit 3 is also configured to be able to communicate with a remote control (not shown) operated by a user of the air conditioning unit 1.

The control unit 3 controls the operation and shutdown of the air conditioning unit 1 and the operation of the various devices that make up the air conditioning unit 1 based on measurement signals from various sensors and commands received from a remote control (not shown).

(2) Configuration of Outdoor Heat Exchanger The configuration of the outdoor heat exchanger 11 will be described with reference to the drawings.

Figure 2 is a schematic perspective view of the outdoor heat exchanger 11. Figure 3 is a partially enlarged view of the heat exchange section 27 (described later) of the outdoor heat exchanger 11. Figure 4 is a schematic diagram showing the attachment state of fins 29 (described later) to the flat tubes 28 in the heat exchange section 27. Figure 5 is an explanatory diagram showing the refrigerant flow in the outdoor heat exchanger 11, which functions as a refrigerant evaporator. The arrows in the heat exchange section 27 shown in Figure 5 indicate the refrigerant flow during heating operation (when the outdoor heat exchanger 11 functions as an evaporator).

In the following description, terms such as "upper," "lower," "left," "right," "front," and "rear" may be used to describe orientations and positions. Unless otherwise specified, these terms refer to the directions of the arrows drawn in Figure 2. Note that these terms used to describe orientations and positions are used for convenience of explanation, and unless otherwise specified, do not specify the orientation or position of the outdoor heat exchanger 11 as a whole or each component of the outdoor heat exchanger 11 as the orientation or position of the terms used.

The outdoor heat exchanger 11 is a device that performs heat exchange between the refrigerant flowing inside and the air.

The outdoor heat exchanger 11 mainly includes a flow divider 22, a flat tube group 28G including a plurality of flat tubes 28, a plurality of fins 29, a liquid header 30 (an example of a header), and a gas header 70. In this embodiment, the flow divider 22, flat tubes 28, fins 29, liquid header 30, and gas header 70 are all made of aluminum or an aluminum alloy.

As described below, the flat tubes 28 and the fins 29 fixed to the flat tubes 28 form a heat exchange section 27. The outdoor heat exchanger 11 has a single row of heat exchange sections 27, rather than multiple flat tubes 28 lined up in the airflow direction. In the outdoor heat exchanger 11, air flows through the ventilation passage formed by the flat tubes 28 and fins 29 of the heat exchange section 27, and heat exchange occurs between the refrigerant flowing through the flat tubes 28 and the air flowing through the ventilation passage. The heat exchange section 27 is divided into a first heat exchange section 27a, a second heat exchange section 27b, a third heat exchange section 27c, a fourth heat exchange section 27d, and a fifth heat exchange section 27e, arranged in the vertical direction.

(2-1) Flow Divider The flow divider 22 is a mechanism for dividing the refrigerant. The flow divider 22 also functions as a mechanism for joining the refrigerant. The liquid refrigerant pipe 20 is connected to the flow divider 22. The flow divider 22 has multiple branch pipes 22a to 22e. The flow divider 22 has the function of dividing the refrigerant that flows into the flow divider 22 from the liquid refrigerant pipe 20 into multiple branch pipes 22a to 22e and guiding it to multiple spaces formed in the liquid header 30. The flow divider 22 also has the function of joining the refrigerant that flows in from the liquid header 30 via the branch pipes 22a to 22e and guiding it to the liquid refrigerant pipe 20. Specifically, each branch pipe 22a to 22e is connected to the multiple spaces in the liquid header 30 via branch liquid refrigerant connection pipes 49a to 49e, respectively.

(2-2) Flat Tube Bundle The flat tube bundle 28G is an example of a heat transfer tube bundle. The flat tube bundle 28G includes a plurality of flat tubes 28 as the plurality of heat transfer tubes. As shown in FIG. 3 , the flat tubes 28 are flat heat transfer tubes having flat surfaces 28a on the top and bottom that serve as heat transfer surfaces. As shown in FIG. 3 , the flat tubes 28 are formed with a plurality of refrigerant passages 28b through which the refrigerant flows. For example, the flat tubes 28 are flat multi-hole tubes formed with a large number of refrigerant passages 28b with small cross-sectional areas through which the refrigerant flows. In this embodiment, these multiple refrigerant passages 28b are arranged side by side in the air flow direction. Note that the maximum width of the flat tubes 28 in a cross section perpendicular to the refrigerant passages 28b may be 70% or more, or may be 85% or more, of the outer diameter of the main gas refrigerant pipe connection portion 19a.

In the outdoor heat exchanger 11, as shown in Figure 5, flat tubes 28 extending horizontally between the liquid header 30 side and the gas header 70 side are arranged in multiple rows, one above the other. As a result, the multiple flat tubes 28 are connected to the rising space 34z (described below) so as to intersect with the longitudinal direction of the liquid header 30 (orthogonal in the case of the outdoor heat exchanger 11). In this embodiment, the flat tubes 28 extending between the liquid header 30 side and the gas header 70 side are bent in two places, and the heat exchange section 27 formed by the flat tubes 28 is formed into a substantially U-shape in plan view. In this embodiment, the multiple flat tubes 28 are arranged vertically at regular intervals.

(2-3) Fins The multiple fins 29 are components for increasing the heat transfer area of the outdoor heat exchanger 11. Each fin 29 is a plate-shaped component extending in the row direction in which the flat tubes 28 are arranged. The outdoor heat exchanger 11 is used in a configuration in which multiple horizontally extending flat tubes 28 are arranged in a vertical direction. Therefore, when the outdoor heat exchanger 11 is installed in the outdoor unit 2, each fin 29 extends in the vertical direction.

As shown in Figure 4, each fin 29 has multiple notches 29a extending along the insertion direction of the flat tubes 28 so that multiple flat tubes 28 can be inserted. The notches 29a extend in the extension direction of the fins 29 and in a direction perpendicular to the thickness direction of the fins 29. When the outdoor heat exchanger 11 is installed in the outdoor unit 2, the notches 29a formed in each fin 29 extend horizontally. The shape of the notches 29a in the fins 29 roughly matches the outer shape of the cross section of the flat tubes 28. The notches 29a are formed in the fins 29 at intervals corresponding to the arrangement spacing of the flat tubes 28. In the outdoor heat exchanger 11, the multiple fins 29 are arranged side by side along the extension direction of the flat tubes 28. By inserting flat tubes 28 into each of the multiple cutouts 29a of the multiple fins 29, the space between adjacent flat tubes 28 is divided into multiple ventilation passages through which air flows.

Each fin 29 has a communication portion 29b that communicates in the vertical direction, located upstream or downstream of the flat tube 28 in the air flow direction. In this embodiment, the communication portion 29b of the fin 29 is located on the upwind side of the flat tube 28.

(2-4) Gas Header and Liquid Header The gas header 70 and the liquid header 30 are cylindrical members having refrigerant flow paths formed therein.

As shown in FIG. 5, the liquid header 30 is connected to one end of each flat tube 28, and the gas header 70 is connected to the other end of each flat tube 28. The outdoor heat exchanger 11 is disposed within the casing (not shown) of the outdoor unit 2 so that the longitudinal directions of the liquid header 30 and the gas header 70 are generally aligned with the vertical direction (an example of the first direction). In this embodiment, the heat exchange section 27 of the outdoor heat exchanger 11 is formed in a U-shape in plan view, as shown in FIG. 2. The liquid header 30 is disposed near the left front corner of the casing (not shown) of the outdoor unit 2. The gas header 70 is disposed near the right front corner of the casing (not shown) of the outdoor unit 2.

(2-4-1) Gas Header Connected to the gas header 70 are a main gas refrigerant pipe connection 19a and a branch gas refrigerant pipe connection 19b which constitute the gas header 70 side ends of the first gas refrigerant pipe 19. Although not particularly limited, the outer diameter of the main gas refrigerant pipe connection 19a may be, for example, three or more times or five or more times the outer diameter of the branch gas refrigerant pipe connection 19b.

One end of the main gas refrigerant pipe connection portion 19a is connected to the gas header 70 at a midpoint in the height direction of the gas header 70 so as to communicate with the gas-side internal space 25, which is the refrigerant flow path of the gas header 70.

One end of the branch gas refrigerant pipe connection portion 19b is connected to the gas header 70 so as to communicate with the gas-side internal space 25 near the lower end of the gas header 70 in the vertical direction. The other end of the branch gas refrigerant pipe connection portion 19b is connected to the main gas refrigerant pipe connection portion 19a. The branch gas refrigerant pipe connection portion 19b has a smaller inner diameter than the main gas refrigerant pipe connection portion 19a and is connected to the gas header 70 below the main gas refrigerant pipe connection portion 19a. This allows refrigeration oil accumulating near the lower end of the gas header 70 to be drawn into the main gas refrigerant pipe connection portion 19a and returned to the compressor 8.

(2-4-2) Liquid Header The liquid-side internal space 23 of the liquid header 30 is partitioned into a plurality of sub-spaces 23 a to 23 e which are refrigerant flow paths of the liquid header 30 .

These multiple sub-spaces 23a-23e are aligned vertically. The sub-spaces 23a-23e are not connected to each other in the liquid-side internal space 23 of the liquid header 30.

The branched liquid refrigerant connection pipes 49a-49e, which are connected to the branch pipes 22a-22e of the flow diverter 22, are connected one-to-one to each of the sub-spaces 23a-23e. As a result, during cooling operation, the refrigerant that reaches each of the sub-spaces 23a-23e flows through the branched liquid refrigerant connection pipes 49a-49e and the branch pipes 22a-22e before joining at the flow diverter 22. During heating operation, the refrigerant branched at the flow diverter 22 flows through the branch pipes 22a-22e and the branched liquid refrigerant connection pipes 49a-49e to be supplied to each of the sub-spaces 23a-23e.

(3) Refrigerant Flow in the Outdoor Heat Exchanger When the air conditioning apparatus 1 performs heating operation and the outdoor heat exchanger 11 functions as a refrigerant evaporator, the refrigerant in a gas-liquid two-phase state that reaches the diverter 22 from the liquid refrigerant pipe 20 flows through the diverter pipes 22a to 22e into each of the subspaces 23a to 23e that constitute the liquid-side internal space 23 of the liquid header 30. Specifically, the refrigerant that flows through the diverter pipe 22a flows into the subspace 23a, the refrigerant that flows through the diverter pipe 22b flows into the subspace 23b, the refrigerant that flows through the diverter pipe 22c flows into the subspace 23c, the refrigerant that flows through the diverter pipe 22d flows into the subspace 23d, and the refrigerant that flows through the diverter pipe 22e flows into the subspace 23e. The refrigerant that flows into the subspaces 23a to 23e of the liquid-side internal space 23 flows through the flat tubes 28 connected to each of the subspaces 23a to 23e. The refrigerant flowing through each flat tube 28 evaporates by exchanging heat with the air, and becomes gas-phase refrigerant, which flows into the gas-side internal space 25 of the gas header 70 and merges with the air.

When the air conditioning unit 1 is in cooling or defrosting operation, refrigerant flows through the refrigerant circuit 6 in the opposite direction to that during heating operation. Specifically, high-temperature gas-phase refrigerant flows into the gas-side internal space 25 of the gas header 70 via the main gas refrigerant pipe connection 19a and branch gas refrigerant pipe connection 19b of the first gas refrigerant pipe 19. The refrigerant that flows into the gas-side internal space 25 of the gas header 70 is split and flows into each flat tube 28. The refrigerant that flows into each flat tube 28 passes through each flat tube 28 and flows into the sub-spaces 23a to 23e of the liquid-side internal space 23 of the liquid header 30. The refrigerant that flows into the sub-spaces 23a to 23e of the liquid-side internal space 23 merges at the flow splitter 22 and flows out into the liquid refrigerant pipe 20.

(4) Details of the Liquid Header Fig. 6 is a side view external configuration diagram showing how the branch liquid refrigerant connection pipes 49a to 49e are connected to the liquid header 30. Fig. 7 is an exploded perspective view of the portion near the upper end of the liquid header 30 (note that in the figure, the two-dot chain arrows indicate the refrigerant flow when the outdoor heat exchanger 11 functions as a refrigerant evaporator). Fig. 8 is a plan cross-sectional view of the liquid header 30. Fig. 9 is a plan cross-sectional view showing how the branch liquid refrigerant connection pipes 49a to 49e and the flat tubes 28 are connected to the liquid header 30. Fig. 10 is a cross-sectional perspective view of the portion near the upper end of the liquid header 30.

The liquid header 30 is configured so that its outer shape in a plan view is a substantially rectangular shape with the connection points of the flat tubes 28 as one side. The liquid header 30 has a first liquid side member 31, a second liquid side member 32, a third liquid side member 33, a fourth liquid side member 34, a fifth liquid side member 35, a sixth liquid side member 36, and a seventh liquid side member 37. The liquid header 30 is configured by joining the first liquid side member 31, the second liquid side member 32, the third liquid side member 33, the fourth liquid side member 34, the fifth liquid side member 35, the sixth liquid side member 36, and the seventh liquid side member 37 together by brazing.

Figure 11 is a schematic view of the first liquid side member 31 seen from the rear. Figure 12 is a schematic view of the second liquid side member 32 seen from the rear. Figure 13 is a schematic view of the third liquid side member 33 seen from the rear. Figure 14 is a schematic view of the fourth liquid side member 34 seen from the rear. Figure 15 is a schematic view of the fifth liquid side member 35 seen from the rear. Figure 16 is a schematic view of the sixth liquid side member 36 seen from the rear. Figure 17 is a schematic view of the seventh liquid side member 37 seen from the rear. Note that in each of these figures, the positional relationship between the openings of adjacently arranged members is projected and indicated by dashed lines, etc.

It is preferable that the first liquid side member 31, the third liquid side member 33, the fourth liquid side member 34, the fifth liquid side member 35, the sixth liquid side member 36, and the seventh liquid side member 37 are all made of plate material with a thickness of 3 mm or less.

(4-1) First Liquid Side Member The first liquid side member 31 is a member that mainly constitutes the periphery of the outer shape of the liquid header 30 together with a seventh liquid side member 37 described later. It is preferable that the first liquid side member 31 has a clad layer containing a brazing material formed on its surface.

The first liquid side member 31 has a liquid side flat tube connecting plate 31a, a first liquid side outer wall 31b, a second liquid side outer wall 31c, a first liquid side claw portion 31d, and a second liquid side claw portion 31e.

Although not particularly limited, the first liquid side member 31 of this embodiment can be formed by bending a single sheet metal obtained by rolling, with the fold line running in the longitudinal direction of the liquid header 30 (an example of the first direction). In this case, the thickness of each portion of the first liquid side member 31 is uniform.

The liquid side flat tube connection plate 31a is a flat plate-shaped portion that extends vertically and horizontally. The liquid side flat tube connection plate 31a has multiple liquid side flat tube connection openings 31x arranged in a vertical line. Each liquid side flat tube connection opening 31x penetrates the liquid side flat tube connection plate 31a in the plate thickness direction. The flat tubes 28 are inserted into the liquid side flat tube connection openings 31x so that one end of each flat tube 28 passes completely through the opening, and then brazed to the flat tubes 28. When brazed, the entire inner circumferential surface of the liquid side flat tube connection opening 31x and the entire outer circumferential surface of the flat tube 28 are in contact with each other. The thickness of the first liquid side member 31, including the liquid side flat tube connection plate 31a, is relatively thin, for example, between 1.0 mm and 2.0 mm, thereby shortening the length of the inner circumferential surface of the gas side flat tube connection opening 71x in the plate thickness direction. Therefore, when inserting the flat tube 28 into the liquid side flat tube connection opening 31x, prior to joining by brazing, it is possible to minimize friction that occurs between the inner surface of the liquid side flat tube connection opening 31x and the outer surface of the flat tube 28, making the insertion process easier.

The first liquid side outer wall 31b is a flat portion that extends forward from the front surface of the left end of the liquid side flat tube connecting plate 31a (outside the outdoor unit 2, opposite the gas header 70).

The second liquid side outer wall 31c is a flat portion that extends forward from the front surface of the right end of the liquid side flat tube connecting plate 31a (inside the outdoor unit 2, on the gas header 70 side).

The first liquid-side claw portion 31d extends to the right from the front end of the first liquid-side outer wall 31b. The second liquid-side claw portion 31e extends to the left from the front end of the second liquid-side outer wall 31c.

When the second liquid side member 32, the third liquid side member 33, the fourth liquid side member 34, the fifth liquid side member 35, the sixth liquid side member 36, and the seventh liquid side member 37 are placed inside the first liquid side member 31 in a planar view, the first liquid side claw portion 31d and the second liquid side claw portion 31e are extended in the same direction as the first liquid side outer wall 31b and the second liquid side outer wall 31c, respectively. When the second liquid side member 32, third liquid side member 33, fourth liquid side member 34, fifth liquid side member 35, sixth liquid side member 36, and seventh liquid side member 37 are arranged inside the first liquid side member 31 in a plan view, the first liquid side claw portion 31d and the second liquid side claw portion 31e are bent toward each other, so that the second liquid side member 32, third liquid side member 33, fourth liquid side member 34, fifth liquid side member 35, sixth liquid side member 36, and seventh liquid side member 37 are crimped and fixed to each other by the first liquid side member 31. In this state, the members are joined and completely fixed to each other by brazing in a furnace or the like.

(4-2) Second Liquid Side Member The second liquid side member 32 has a plate-shaped base portion 32a and a plurality of protrusions 32b protruding from the base portion 32a toward the liquid side flat tube connecting plate 31a. The second liquid side member 32 does not need to have a clad layer containing a brazing material formed on its surface.

The base portion 32a extends parallel to the liquid side flat tube connecting plate 31a and has a plate-like shape with the thickness direction being the extension direction of the flat tubes 28. The width of the base portion 32a in the left-right direction is the same as the width of the liquid side flat tube connecting plate 31a in the left-right direction excluding both end portions. The base portion 32a has a plurality of communication holes 32x arranged in a vertical line in one-to-one correspondence with the flat tubes 28, except at the positions where the protrusions 32b are provided. The communication holes 32x are shaped so that they generally overlap the ends of the flat tubes 28 when viewed from the rear.

The protrusions 32b extend horizontally from between adjacent communication holes 32x toward the rear of the base portion 32a until they contact the front surface of the liquid side flat tube connecting plate 31a. This forms an insertion space 32s surrounded by the front surface of the liquid side flat tube connecting plate 31a of the first liquid side member 31, the first liquid side outer wall 31b and the second liquid side outer wall 31c of the first liquid side member 31, the vertically adjacent protrusions 32b of the second liquid side member 32, and the portion of the rear surface of the base portion 32a of the second liquid side member 32 other than the communication holes 32x. Multiple insertion spaces 32s are arranged in a line along the longitudinal direction of the liquid header 30. The ends of the flat tubes 28 are positioned in the insertion spaces 32s. The length of the protrusion 32b in the front-to-rear direction is adjusted to be longer than the thickness of any of the first liquid side member 31, third liquid side member 33, fourth liquid side member 34, fifth liquid side member 35, sixth liquid side member 36, and seventh liquid side member 37 that make up the liquid header 30. This ensures that even if there is an error in the degree of insertion of the flat tubes 28 into the liquid header 30, problems such as blockages or areas where refrigerant flow is difficult are unlikely to occur in the completed liquid header 30, as long as the length of the protrusion 32b in the front-to-rear direction is within the range. This also makes it possible to prevent the brazing material from moving due to capillary action during brazing and blocking the refrigerant passages 28b of the flat tubes 28.

(4-3) Third Liquid Side Member The third liquid side member 33 is a member laminated so as to face and contact the front surface (the connection position side between the branch liquid refrigerant connection pipes 49a to 49e and the liquid header 30) of the base portion 32a of the second liquid side member 32. The left-right length of this third liquid side member 33 is the same as the left-right length of the second liquid side member 32. It is preferable that the third liquid side member 33 has a clad layer containing a brazing material formed on its surface.

The third liquid side member 33 has a third internal plate 33a and multiple flow diversion openings 33x.

The third internal plate 33a has a flat plate shape that extends in the vertical and horizontal directions.

The multiple diverter openings 33x are arranged in a vertical line and are openings that penetrate the third internal plate 33a in the plate thickness direction. In this embodiment, each diverter opening 33x is formed near the center of the third internal plate 33a in the left-right direction. When viewed from the rear, each diverter opening 33x overlaps with a corresponding communication hole 32x of the second liquid side member 32 and communicates with each other. This allows the refrigerant flowing through the ascending space 34z (described below) to branch off and flow toward each diverter opening 33x, and the refrigerant can be diverted to each flat tube 28 connected to each diverter opening 33x.

The front surface of the third internal plate 33a, excluding the portion where the flow-diversion opening 33x is formed, forms the outline of the ascending space 34z, which will be described later.

(4-4) Fourth Liquid Side Member The fourth liquid side member 34 is a member laminated so as to face and contact the front surface (the connecting position side between the branch liquid refrigerant connecting pipes 49a to 49e and the liquid header 30) of the third internal plate 33a of the third liquid side member 33. The left-right length of this fourth liquid side member 34 is the same as the left-right length of the third liquid side member 33. The fourth liquid side member 34 does not need to have a clad layer containing a brazing material formed on its surface.

The fourth liquid side member 34 has a fourth internal plate 34a and a first through portion 34o.

The fourth internal plate 34a has a flat plate shape that extends in the vertical and horizontal directions.

The first penetrating portion 34o is an opening formed through the fourth internal plate 34a in the plate thickness direction, and includes an introduction space 34x, a nozzle 34y, and an ascending space 34z (an example of a first flow path). In this embodiment, the introduction space 34x, the nozzle 34y, and the ascending space 34z are arranged vertically from bottom to top. In this embodiment, the introduction space 34x, the nozzle 34y, and the ascending space 34z have the same width in the front-to-rear direction.

The introduction space 34x, nozzle 34y, and rising space 34z are spaces sandwiched in the front-to-rear direction between the front surface of the third internal plate 33a of the third liquid side member 33 and the rear surface of the fifth internal plate 35a of the fifth liquid side member 35 (described below).

The introduction space 34x faces the wall portion 33aa of the third internal plate 33a of the third liquid side member 33, and does not overlap with the flow diversion opening 33x when viewed from the rear, and is not connected to the flow diversion opening 33x. When viewed from the rear, the introduction space 34x overlaps with the second communication opening 35x of the fifth liquid side member 35 (described below), and is connected to the second communication opening 35x. Because the rear side of the introduction space 34x is thus covered by the wall portion 33aa of the third internal plate 33a, the gas-phase refrigerant and liquid-phase refrigerant that flow into the introduction space 34x mix upon impact with the wall portion 33aa, and are then sent to the rising space 34z via the nozzle 34y.

Nozzle 34y faces the third internal plate 33a of the third liquid side member 33, and does not overlap with the flow diversion opening 33x when viewed from the rear, and is not connected to the flow diversion opening 33x. Furthermore, nozzle 34y faces the fifth internal plate 35a of the fifth liquid side member 35 (described below), and does not overlap with the second communication opening 35x, return flow path 35y, or forward flow path 35z when viewed from the rear, and is not connected to any of these. Nozzle 34y is located near the center of the fourth internal plate 34a in the left-right direction.

When the outdoor heat exchanger 11 functions as a refrigerant evaporator, the rise space 34z has an inlet 34e formed at the connection with the nozzle 34y, through which refrigerant that has passed through the nozzle 34y flows. The rise space 34z is a flow path that extends from the inlet 34e along the longitudinal direction of the liquid header 30 to the upper end side (an example of the first end side) of the liquid header 30. The rise space 34z faces the third internal plate 33a of the third liquid side member 33, and overlaps with and is connected to multiple branch openings 33x when viewed from the rear.

The flow path cross-sectional area A of the rising space 34z is formed so that the flow path cross-sectional area A at the first position P1 differs from the flow path cross-sectional area A at the second position P2, which is a predetermined distance from the first position P1 toward the upper end of the liquid header 30. The first position P1 is at or near the inlet 34e. The flow path cross-sectional area A increases from the first position P1 toward the second position P2. In the outdoor heat exchanger 11, the second position P2 is located at the upper end of the rising space 34z.

In the outdoor heat exchanger 11, as one moves from the first position P1 toward the upper end of the liquid header 30, the flow path cross-sectional area A changes due to the change in the flow path cross-sectional shape of the rise space 34z in a direction (left-right direction in this embodiment) perpendicular to the longitudinal direction of the flat tubes 28 as viewed from the extension direction (up-down direction) of the rise space 34z. In other words, in the outdoor heat exchanger 11, as one moves from the first position P1 toward the upper end of the liquid header 30, the flow path cross-sectional area A changes due to the change in the left-right width of the rise space 34z.

The ascending space 34z faces the fifth internal plate 35a of the fifth liquid side member 35 (described later), and when viewed from the rear, does not overlap with the second communication opening 35x, but overlaps with the return flow path 35y and the forward flow path 35z. Furthermore, the ascending space 34z does not communicate with the second communication opening 35x, but communicates with the return flow path 35y and the forward flow path 35z. The length of the ascending space 34z in the longitudinal direction of the liquid header 30 is longer than the length of the introduction space 34x in the longitudinal direction of the liquid header 30, and longer than the length of the nozzle 34y in the longitudinal direction of the liquid header 30. This allows for an increase in the number of flat tubes 28 communicating via the ascending space 34z.

The rising space 34z forms a refrigerant flow path, through which the refrigerant flows upward along the longitudinal direction of the liquid header 30, and is formed by the front surface of the third internal plate 33a of the third liquid side member 33, the rear surface of the fifth internal plate 35a of the fifth liquid side member 35 (described below), and the thickness portions of the left and right edges of the first through portion 34o of the fourth internal plate 34a of the fourth liquid side member 34. This structure makes it less likely for errors in the flow path cross-sectional area to occur during manufacturing, and makes it easier to obtain a liquid header 30 that can steadily rise and allow the refrigerant to flow.

The length (width) of the nozzle 34y in the left-right direction is shorter than the length of the introduction space 34x in the left-right direction and shorter than the minimum length of the rise space 34z in the left-right direction. As a result, when the outdoor heat exchanger 11 is used as a refrigerant evaporator, the flow velocity of the refrigerant sent to the introduction space 34x increases as it passes through the nozzle 34y, facilitating its arrival at the upper part of the rise space 34z. The length of the nozzle 34y in the left-right direction is longer than the thickness of the fourth inner plate 34a. This allows for a larger opening width relative to the plate thickness. Therefore, for example, when forming the first through portion 34o in the fourth inner plate 34a by punching, the load on the punch portion corresponding to the nozzle 34y is reduced, preventing damage to the punch portion. When viewed from the front-to-rear direction, the branch liquid refrigerant connection pipes 49a-49e are connected to the left-to-right center of the introduction space 34x. When viewed from the front-to-rear direction, the connection points of the branch liquid refrigerant connecting pipes 49a-49e corresponding to the introduction space 34x, the nozzles 34y, and the rising space 34z are aligned vertically. Therefore, the refrigerant flowing through the branch liquid refrigerant connecting pipes 49a-49e flows into the center of the introduction space 34x in the left-right direction through the external liquid pipe connection openings 37x, the first communication openings 36x, and the second communication openings 35x (described later) and is then blown vertically upward from the introduction space 34x through the nozzles 34y toward the rising space 34z without or with significant left-to-right movement. When viewed from the rear, the multiple branch openings 33x of the third liquid side member 33 are all positioned to overlap within a virtual region (the region sandwiched between the virtual line VL in FIG. 14 ) obtained by virtually extending the nozzles 34y in the longitudinal direction of the liquid header 30. When the outdoor heat exchanger 11 functions as a refrigerant evaporator, the refrigerant that passes through the nozzle 34y increases in flow velocity and flows upward, but liquid refrigerant tends to stagnate in the left and right spaces of the rising space 34z slightly above the nozzle 34y. By arranging the multiple diverter openings 33x and the nozzle 34y as described above, it is possible to prevent liquid refrigerant from concentrating its flow toward the diverter opening 33x located at the lowest position in the rising space 34z.

(4-5) Fifth Liquid Side Member The fifth liquid side member 35 is a member laminated so as to face and contact the front surface (the side where the branch liquid refrigerant connecting pipes 49a to 49e are connected to the liquid header 30) of the fourth internal plate 34a of the fourth liquid side member 34. The left-right length of this fifth liquid side member 35 is the same as the left-right length of the fourth liquid side member 34. It is preferable that a clad layer containing a brazing material is formed on the surface of the fifth liquid side member 35.

The fifth liquid side member 35 has a fifth internal plate 35a, a second communication opening 35x, a return flow path 35y (an example of a second communication port), and a forward flow path 35z (an example of a first communication port).

The fifth internal plate 35a has a flat plate shape that extends in the vertical and horizontal directions.

The second communication opening 35x, the return flow path 35y, and the forward flow path 35z are independent openings arranged in a row from bottom to top, and all penetrate the fifth internal plate 35a in the plate thickness direction.

When viewed from the rear, the second communication opening 35x overlaps with the introduction space 34x of the first through-portion 34o of the fourth liquid side member 34, and they are in communication with each other. When viewed from the rear, the second communication opening 35x also overlaps with the first communication opening 36x of the sixth liquid side member 36, which will be described later, and they are in communication with each other. When viewed from the rear, the second communication opening 35x does not overlap with or communicate with the nozzle 34y or the ascending space 34z of the first through-portion 34o of the fourth liquid side member 34. When viewed from the rear, the second communication opening 35x also does not overlap with or communicate with the descending space 36y of the sixth liquid side member 36, which will be described later.

When viewed from the rear, the return flow path 35y overlaps with a portion of the first penetrating portion 34o of the fourth liquid side member 34 near the bottom end of the ascending space 34z (the end opposite the forward flow path 35z), and is connected to the portion near the bottom end of the ascending space 34z. Also, when viewed from the rear, the return flow path 35y overlaps with a portion near the bottom end of the descending space 36y of the sixth liquid side member 36, and is connected to the portion near the bottom end of the descending space 36y. When viewed from the rear, the return flow path 35y does not overlap with the nozzle 34y, and is not connected to the nozzle 34y.

When viewed from the rear, the forward flow path 35z overlaps with a portion of the first through-port 34o of the fourth liquid side member 34 near the upper end of the ascending space 34z (the end opposite the inlet 34e), and is connected to the portion near the upper end of the ascending space 34z. When viewed from the rear, the forward flow path 35z also overlaps with a portion near the upper end of the descending space 36y of the sixth liquid side member 36, and is connected to the portion near the upper end of the descending space 36y. In this embodiment, when the liquid header 30 is viewed from the stacking direction of the components, the area of the forward flow path 35z is larger than the area of the return flow path 35y. Specifically, in this embodiment, the width of the forward flow path 35z in the longitudinal direction of the liquid header 30 is longer than the width of the return flow path 35y in the longitudinal direction of the liquid header 30. This allows refrigerant that rises in the ascending space 34z and reaches the vicinity of the upper end to easily pass through the forward flow path 35z. Furthermore, in this embodiment, when the liquid header 30 is viewed in the stacking direction of the components, the area of the return flow path 35y is smaller than the area of the forward flow path 35z. Specifically, in this embodiment, the width of the return flow path 35y in the longitudinal direction of the liquid header 30 is smaller than the width of the forward flow path 35z in the longitudinal direction of the liquid header 30. This prevents refrigerant from flowing back from the upflow space 34z to the return flow path 35y.

(4-6) Sixth Liquid Side Member The sixth liquid side member 36 is a member laminated so as to face and contact the front surface (the connecting position side between the branch liquid refrigerant connecting pipes 49a to 49e and the liquid header 30) of the fifth internal plate 35a of the fifth liquid side member 35. The left-right length of this sixth liquid side member 36 is the same as the left-right length of the fifth liquid side member 35. The sixth liquid side member 36 does not need to have a clad layer containing a brazing material formed on its surface.

The sixth liquid side member 36 has a sixth internal plate 36a, a first communication opening 36x, and a downward space 36y (an example of a second flow path).

The sixth internal plate 36a has a flat plate shape that extends in the vertical and horizontal directions.

The first communication opening 36x and the descending space 36y are independent openings arranged next to each other from the bottom up, and both penetrate the sixth internal plate 36a in the plate thickness direction.

When viewed from the rear, the first communication opening 36x overlaps with the second communication opening 35x of the fifth liquid side member 35, and the two are in communication with each other. Furthermore, when viewed from the rear, the first communication opening 36x overlaps with the external liquid pipe connection opening 37x of the seventh liquid side member 37 (described below), and the two are in communication with each other.

The descending space 36y is connected to the forward flow path 35z and is a flow path that extends from the forward flow path 35z along the longitudinal direction of the liquid header 30 to the lower end side (an example of the second end side) of the liquid header 30. When viewed from the rear, the descending space 36y overlaps with a portion of the fifth internal plate 35a of the fifth liquid side member 35, the return flow path 35y, and the forward flow path 35z, and is connected to the return flow path 35y and the forward flow path 35z. When viewed from the rear, the descending space 36y does not overlap with the external liquid pipe connection opening 37x of the seventh liquid side member 37 (described later), nor are they connected to each other.

In the longitudinal direction of the liquid header 30, the length of the descending space 36y is the same as the length of the ascending space 34z. Therefore, the ascending space 34z and the descending space 36y are connected near the upper end via the forward flow path 35z, and near the lower end via the return flow path 35y. Therefore, the ascending space 34z, the forward flow path 35z, the descending space 36y, and the return flow path 35y form a loop structure in which the refrigerant loops (circulates) inside. Specifically, the refrigerant that flows into the ascending space 34z from the inlet 34e flows into the descending space 36y from the forward flow path 35z, then flows into the ascending space 34z through the return flow path 35y.

(4-7) Seventh Liquid Side Member The seventh liquid side member 37 is a member laminated so as to face and contact the front surface (the connecting position side between the branch liquid refrigerant connecting pipes 49a to 49e and the liquid header 30) of the sixth internal plate 36a of the sixth liquid side member 36. The left-right length of this seventh liquid side member 37 is the same as the left-right length of the sixth liquid side member 36. It is preferable that the seventh liquid side member 37 has a clad layer containing a brazing material formed on its surface.

The seventh liquid side member 37 has a liquid side external plate 37a and an external liquid pipe connection opening 37x.

The liquid-side outer plate 37a has a flat plate shape that extends in the vertical and horizontal directions.

The external liquid pipe connection opening 37x is an opening that penetrates the liquid side external plate 37a in the plate thickness direction. When viewed from the rear, the external liquid pipe connection opening 37x overlaps with a portion of the first communication opening 36x of the sixth liquid side member 36, and the two are in communication with each other. When viewed from the rear, the external liquid pipe connection opening 37x does not overlap with or communicate with the descending space 36y of the sixth liquid side member 36.

The external liquid pipe connection opening 37x is a circular opening into which one of the branch liquid refrigerant connection pipes 49a-49e is inserted and connected. As a result, when the outdoor heat exchanger 11 functions as a refrigerant evaporator, the refrigerant flowing through each branch liquid refrigerant connection pipe 49a-49e is sent to the inlet space 34x of the first through-portion 34o via the first communication opening 36x and the second communication opening 35x.

The front surface of the seventh liquid side member 37 is in contact with and crimped to the first liquid side claw portion 31d and the second liquid side claw portion 31e of the first liquid side member 31.

(4-8) Regarding the repetition of the shapes of the sub-spaces The above description focuses on one of the sub-spaces 23a to 23e, which is connected to one of the branch liquid refrigerant connection pipes 49a to 49e, among the multiple sub-spaces 23a to 23e that constitute the liquid side internal space 23 of the liquid header 30.

Therefore, for example, in the seventh liquid side member 37, the external liquid pipe connection openings 37x corresponding to the branch liquid refrigerant connection pipes 49a to 49e are formed in a single liquid side external plate 37a, aligned in the longitudinal direction of the liquid header 30. Similarly, in the fourth liquid side member 34, the first through portion 34o, which includes the introduction space 34x, nozzle 34y, and rising space 34z, is formed in a single fourth internal plate 34a, aligned in the longitudinal direction of the liquid header 30.

(5) Refrigerant Flow in the Liquid Header The following describes the refrigerant flow in the liquid header 30 when the outdoor heat exchanger 11 functions as a refrigerant evaporator. When the outdoor heat exchanger 11 functions as a refrigerant condenser or radiator, the refrigerant flows in the opposite direction to when the outdoor heat exchanger 11 functions as an evaporator.

First, the liquid-phase refrigerant or gas-liquid two-phase refrigerant that is divided into multiple branch pipes 22a-22e in the flow divider 22 flows through the branch liquid refrigerant connection pipes 49a-49e, passes through the external liquid pipe connection openings 37x formed in the liquid-side external plate 37a of the seventh liquid-side member 37, and flows into each of the sub-spaces 23a-23e of the liquid header 30. Specifically, the refrigerant flows into the first communication openings 36x in each of the sub-spaces 23a-23e.

The refrigerant that flows into the first communication opening 36x flows through the second communication opening 35x into the introduction space 34x in the first through portion 34o of the fourth liquid side member 34.

The refrigerant that flows into the introduction space 34x has its flow velocity increased as it passes through the nozzle 34y, and then flows into the ascending space 34z from the inlet 34e. The refrigerant that flows into the ascending space 34z branches off and flows toward each branch opening 33x, heading toward the upper end of the ascending space 34z. The refrigerant that reaches the upper end of the ascending space 34z flows into the descending space 36y via the forward flow path 35z.

The refrigerant that flows into the descending space 36y descends and is returned via the return flow path 35y to the space above the nozzle 34y, near the bottom of the ascending space 34z. Because the flow rate of the refrigerant increases in the ascending space 34z as it passes through the nozzle 34y, the static pressure in the ascending space 34z near the return flow path 35y is lower than that in the descending space 36y near the return flow path 35y. Therefore, the refrigerant that descends in the descending space 36y is more likely to return to the ascending space 34z via the return flow path 35y.

In this way, the refrigerant can be looped (circulated) through the ascending space 34z, the forward flow path 35z, the descending space 36y, and the return flow path 35y. Even if refrigerant branches off into one of the branch openings 33x as it flows upward through the ascending space 34z and does not flow, it can be returned to the ascending space 34z via the forward flow path 35z, the descending space 36y, and the return flow path 35y, making it easier for it to flow into one of the branch openings 33x. Furthermore, even if a two-phase refrigerant flows in, mixing of the liquid and gas phase refrigerants is promoted.

In this way, the refrigerant that is diverted and flows through the diverter opening 33x flows into each flat tube 28 through the insertion space 32s while remaining in a diverted state.

(6) Features of the embodiment (6-1)
The outdoor heat exchanger 11 includes a plurality of flat tubes 28 and a cylindrical liquid header 30. The liquid header 30 has sub-spaces 23a-23e formed therein, which are connected to the plurality of flat tubes 28. The sub-spaces 23a-23e each include an ascending space 34z, a forward flow path 35z, and a descending space 36y. The ascending space 34z extends from an inlet 34e, through which the refrigerant flows, to the upper end of the liquid header 30 along the longitudinal direction of the liquid header 30. The forward flow path 35z communicates with the end of the ascending space 34z opposite the inlet 34e. The descending space 36y communicates with the forward flow path 35z and extends from the forward flow path 35z to the lower end of the liquid header 30 along the longitudinal direction of the liquid header 30. The plurality of flat tubes 28 are connected to the ascending space 34z so as to intersect the longitudinal direction of the liquid header 30. The ascending space 34z has a flow path cross-sectional area A at the first position P1 that is different from the flow path cross-sectional area A at the second position P2 that is a predetermined distance away from the first position P1 toward the upper end of the liquid header 30.

When the air conditioning unit 1 is in heating operation and the outdoor heat exchanger 11 functions as a refrigerant evaporator, the two-phase gas-liquid refrigerant that reaches the diverter 22 from the liquid refrigerant pipe 20 flows through the diverter pipes 22a-22e into each of the sub-spaces 23a-23e that make up the liquid-side internal space 23 of the liquid header 30. If an imbalance in pressure occurs in the two-phase gas-liquid refrigerant that has flowed into each of the sub-spaces 23a-23e, this can result in a biased flow in the distribution of liquid and gas refrigerant in the multiple flat tubes 28 connected to each of the sub-spaces 23a-23e.

In the outdoor heat exchanger 11, this is resolved by making the flow path cross-sectional area A different between the first position P1 and the second position P2 of the rising space 34z, thereby suppressing the occurrence of uneven flow in the flat tubes 28. Specifically, in the rising space (not shown) where the flow path cross-sectional area A is constant from the inlet 34e to the upper end, a location where the distribution of liquid-phase refrigerant is reduced is identified, and the flow path cross-sectional area A at that location is made larger than in other parts. This eliminates the imbalance in the pressure distribution of the refrigerant in the rising space 34z, suppressing the occurrence of uneven flow in the flat tubes 28.

(6-2)
The first position P1 is near the inlet.

(6-3)
The downflow space 36y has a return flow path 35y that communicates with the upflow space 34z at an end opposite to the forward flow path 35z. The refrigerant that flows into the upflow space 34z from the inlet 34e flows into the downflow space 36y from the forward flow path 35z, and then flows into the upflow space 34z through the return flow path 35y.

The outdoor heat exchanger 11 loops (circulates) the refrigerant through the ascending space 34z, the forward flow path 35z, the descending space 36y, and the return flow path 35y, promoting mixing of the liquid-phase refrigerant and the gas-phase refrigerant, thereby eliminating imbalances in the pressure distribution in the ascending space 34z.

(6-4)
The flow path cross-sectional area A increases from the first position P1 toward the second position P2.

The above-mentioned drift in the flat tubes 28 varies depending on the dryness of the refrigerant in the liquid header 30 and the amount of refrigerant circulating. Specifically, in the ascending space 34z, where the flow path cross-sectional area A is constant from the inlet 34e to the upper end, if the dryness of the refrigerant at the refrigerant inlet of the outdoor heat exchanger 11 (the junction between the subspaces 23a-23e and the branched liquid refrigerant connecting pipes 49a-49e) is greater than 0.25 and the average flow velocity Vm of the refrigerant in the ascending space 34z is 2 m/sec or less, the amount of gas-phase refrigerant tends to increase toward the top of the ascending space 34z. As a result, more gas-phase refrigerant tends to flow into the flat tubes 28 located above the flat tube group 28G.

In the outdoor heat exchanger 11, the ascending space 34z is formed so that the flow path cross-sectional area A increases from the first position P1 toward the second position P2. Therefore, the refrigerant flowing in from the inlet 34e is encouraged to move upward in the ascending space 34z. As a result, the outdoor heat exchanger 11 moves the liquid-phase refrigerant flowing in from the inlet 34e together with the gas-phase refrigerant upward in the ascending space 34z, eliminating any imbalance in the pressure distribution in the ascending space 34z.

The average flow velocity Vm of the refrigerant can be calculated by the following formula 1.

The refrigerant circulation rate Gr can be calculated using known methods based on the rotation speed of compressor 8, the pressure and temperature of the refrigerant drawn into compressor 8, the pressure of the refrigerant flowing through the discharge side of compressor 8, and the piston displacement and efficiency in compressor 8.

The average density ρm of the refrigerant can be calculated using the following equation 2.

(6-5)
The flow path cross section of the rising space 34z changes in shape in a direction perpendicular to the longitudinal direction of the flat tubes 28 from the first position P1 toward the upper end side of the liquid header 30.

(6-6)
The longitudinal direction of the liquid header 30 coincides with the vertical direction.

(6-7)
The air conditioner 1 performs an operation in which the quality fraction of the refrigerant at the inlet of the outdoor heat exchanger 11 is 0.25 or more.

As described above, when the quality of the refrigerant at the refrigerant inlet of the outdoor heat exchanger 11 is 0.25 or higher, an imbalance in the pressure distribution in the rising space 34z is likely to occur. Therefore, the outdoor heat exchanger 11 can effectively suppress the occurrence of uneven flow in the flat tubes 28 in an air conditioning apparatus 1 that operates with a quality of the refrigerant of 0.25 or higher.

Operation in which the refrigerant quality is 0.25 or higher is, for example, operation in which two-phase transport is performed, in which gas-liquid refrigerant flows through the liquid refrigerant connection pipe 4 and is sent from the outdoor unit 2 to the indoor unit 9.

(6-8)
The refrigerant circuit 6 is filled with a single refrigerant made of any one of propane, CO ₂ and isobutane, or a mixed refrigerant containing any one of propane, CO ₂ and isobutane.

In a refrigerant circuit filled with a natural refrigerant such as propane, CO ₂ , or isobutane, the quality of the refrigerant at the inlet of the heat exchanger tends to be high. However, by employing the outdoor heat exchanger 11, the occurrence of uneven flow in the flat tubes 28 is suppressed even when a natural refrigerant such as propane, CO ₂ , or isobutane is used.

(7) Modifications (7-1) Modification 1A
The manner in which the flow path cross-sectional area A is changed from the first position P1 toward the upper end of the liquid header 30 is not limited to the manner described above. The flow path cross-sectional area A may be changed by changing the flow path cross-sectional shape of the upflow space 34z in the longitudinal direction of the flat tubes 28 as viewed from the extension direction of the upflow space 34z from the first position P1 toward the upper end of the liquid header 30. In other words, the flow path cross-sectional area A may be changed by changing the width of the upflow space 34z in the front-to-rear direction from the first position P1 toward the upper end of the liquid header 30.

Specifically, for example, the surface of the third internal plate 33a facing the rising space 34z may be formed so as to recess rearward as it moves from the first position P1 toward the upper end of the liquid header 30. Similarly, the surface of the fifth internal plate 35a facing the rising space 34z may be formed so as to recess forward as it moves from the first position P1 toward the upper end of the liquid header 30. Figure 18 is a cross-sectional view of the rising space 34z and its periphery in the outdoor heat exchanger 11 according to Modification 1A, viewed from the right side. In the liquid header 30 of the outdoor heat exchanger 11 according to Modification 1A shown in Figure 18, recesses are formed in both the third internal plate 33a and the fifth internal plate 35a.

(7-2) Modification 1B
In the outdoor heat exchanger 11, the liquid header 30 defines a plurality of sub-spaces 23a to 23e, which are refrigerant flow paths, by a first liquid side member 31, a second liquid side member 32, a third liquid side member 33, a fourth liquid side member 34, a fifth liquid side member 35, a sixth liquid side member 36, and a seventh liquid side member 37. However, the sub-spaces 23a to 23e may also be formed by combining a plurality of tubular members, for example.

Therefore, the ascending space 34z may also be formed by a tubular member in which the flow path cross-sectional area A at the first position P1 is different from the flow path cross-sectional area A at the second position P2, which is a predetermined distance away from the first position P1 toward the upper end of the liquid header 30.

Second Embodiment
An outdoor heat exchanger (not shown) according to a second embodiment of the present disclosure will be described, focusing on differences from the first embodiment. The outdoor heat exchanger according to the second embodiment differs from the outdoor heat exchanger 11 in the shape of the rising space 34z1 formed in the fourth liquid side member 38 of the liquid header 30. In the following, features that are the same as or correspond to those of the first embodiment will be denoted by the same reference numerals and will not be described again.

(1) Rising Space of Fourth Liquid Side Member Fig. 19 is an exploded perspective view of a portion near the upper end of the liquid header 30 of the outdoor heat exchanger according to the second embodiment. Fig. 20 is a schematic view of the fourth liquid side member 38 of the liquid header 30 of the outdoor heat exchanger according to the second embodiment, viewed from the rear.

When the outdoor heat exchanger 11 functions as a refrigerant evaporator, the rising space 34z1 has an inlet 34e formed at the connection with the nozzle 34y, through which refrigerant that has passed through the nozzle 34y flows. The rising space 34z1 is a flow path that extends from the inlet 34e to the upper end of the liquid header 30 along the longitudinal direction of the liquid header 30. The rising space 34z1 faces the third internal plate 33a of the third liquid side member 33, overlaps with multiple branch openings 33x when viewed from the rear, and is connected to multiple branch openings 33x.

The flow path cross-sectional area A of the rising space 34z1 is formed so that the flow path cross-sectional area A at the first position P1 differs from the flow path cross-sectional area A at the second position P2, which is a predetermined distance from the first position P1 toward the upper end of the liquid header 30. The first position P1 is near the inlet 34e or the inlet 34e. The flow path cross-sectional area A increases from the first position P1 toward the second position P2. In the outdoor heat exchanger according to the second embodiment, the second position P2 is located approximately in the center of the rising space 34z1 in the longitudinal direction of the liquid header 30. The flow path cross-sectional area A of the rising space 34z1 decreases from the second position P2 toward the upper end of the liquid header 30, and reaches the same flow path cross-sectional area A at the upper end of the liquid header 30 as the first position P1.

In the outdoor heat exchanger according to the second embodiment, the flow path cross-sectional area A changes as the flow path cross-sectional shape of the ascending space 34z1 changes in a direction (left-right direction in this embodiment) perpendicular to the longitudinal direction of the flat tubes 28 as viewed from the extension direction (up-down direction) of the ascending space 34z1 from the first position P1 toward the upper end of the liquid header 30. In other words, in the outdoor heat exchanger according to the second embodiment, the flow path cross-sectional area A changes as the flow path cross-sectional area A changes as the flow path cross-sectional shape of the ascending space 34z1 changes in the left-right direction as viewed from the first position P1 toward the upper end of the liquid header 30.

(2) Features In the outdoor heat exchanger according to the second embodiment, the second position P2 of the rising space 34z1 is located at the center in the longitudinal direction of the liquid header 30. The flow path cross-sectional area A decreases from the second position P2 toward the upper end of the liquid header 30.

In the ascending space 34z, where the flow path cross-sectional area A is constant from the inlet 34e to the upper end, if the quality fraction of the refrigerant at the refrigerant inlet of the outdoor heat exchanger 11 is greater than 0.25 and the average flow velocity Vm of the refrigerant in the ascending space 34z is greater than 2 m/s, the amount of gas-phase refrigerant tends to increase toward the center of the ascending space 34z. As a result, more gas-phase refrigerant tends to flow into the flat tubes 28 located in the vertical center of the flat tube group 28G.

In the outdoor heat exchanger according to the second embodiment, the second position P2 is located approximately in the center of the ascending space 34z1 in the longitudinal direction of the liquid header 30. The flow path cross-sectional area A increases from the first position P1 toward the second position P2, and then decreases from the second position P2 toward the upper end of the liquid header 30. This promotes the vertical movement of the refrigerant flowing in from the inlet 34e toward the center of the ascending space 34z. As a result, the outdoor heat exchanger according to the second embodiment moves the liquid-phase refrigerant flowing in from the inlet 34e, together with the gas-phase refrigerant, to the center of the ascending space 34z, eliminating any imbalance in the pressure distribution in the ascending space 34z.

(3) Modification 2A
The manner in which the flow path cross-sectional area A is increased from the first position P1 toward the second position P2 is not limited to the manner described above. The flow path cross-sectional area A may also be changed by changing the flow path cross-sectional shape of the upflow space 34z in the longitudinal direction of the flat tubes 28 as viewed from the extension direction of the upflow space 34z1 from the first position P1 toward the upper end of the liquid header 30. In other words, the flow path cross-sectional area A may also be increased by increasing the width of the upflow space 34z1 in the front-to-rear direction from the first position P1 toward the upper end of the liquid header 30.

Specifically, for example, the surface of the third internal plate 33a facing the rising space 34z1 may be formed so as to recess rearward from the first position P1 and the upper end of the liquid header 30 toward the second position P2. Similarly, the surface of the fifth internal plate 35a facing the rising space 34z1 may be formed so as to recess forward from the first position P1 and the upper end of the liquid header 30 toward the second position P2. Figure 21 is a cross-sectional view of the rising space 34z1 and its periphery of the outdoor heat exchanger according to Modification 2A, viewed from the right side. In the liquid header 30 of the outdoor heat exchanger according to Modification 2A shown in Figure 21, recesses are formed in both the third internal plate 33a and the fifth internal plate 35a.

Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details may be made without departing from the spirit and scope of the present disclosure as set forth in the claims.

1 Air conditioning device 11 Outdoor heat exchanger (heat exchanger)
23 Liquid side internal space 23a to 23e Sub-spaces (refrigerant flow paths)
28 Flat tube (heat transfer tube)
30 Liquid header (header)
34e inlet 34z ascending space (first flow path)
35y Return flow path (second communication port)
35z Outgoing flow path (first communication port)
36y: descending space (second flow path)
A Flow path cross-sectional area P1 First position P2 Second position

JP 2016-125748 A

Claims (9)

a plurality of heat transfer tubes (28);
a cylindrical header (30) having refrigerant flow paths (23a to 23e) connected to the plurality of heat transfer tubes formed therein,
The refrigerant flow path is
a first flow path (34z) extending from an inlet (34e) through which a refrigerant flows to a first end side of the header along a first direction which is the longitudinal direction of the header;
a first communication port (35z) communicating with an end of the first flow path opposite to the inlet;
a second flow path (36y) communicating with the first communication port and extending from the first communication port to a second end side of the header along the first direction;
The plurality of heat transfer tubes include
connected to the first flow path so as to intersect with the first direction,
The first flow path is
a flow path cross-sectional area (A) at a first position (P1) is different from the flow path cross-sectional area at a second position (P2) that is a predetermined distance away from the first position toward the first end of the header,
The flow path cross-sectional area is
increasing from the first position to the second position,
heat exchanger. The first position is
near the inlet,
The heat exchanger of claim 1 . The refrigerant flow path is
The second flow path further has a second communication port (35y) communicating with the first flow path at an end of the second flow path opposite to the first communication port,
The refrigerant that flows into the first flow path from the inlet
the liquid flows from the first communication port into the second flow path, and then flows into the first flow path through the second communication port;
3. The heat exchanger according to claim 1 or 2. The second position is
Located at the center in the first direction,
The flow path cross-sectional area is
decreases from the second position toward the first end of the header.
A heat exchanger according to any one of claims 1 to 3 . The cross section of the first flow path is
a shape of the heat transfer tube changes in a direction perpendicular to a longitudinal direction of the heat transfer tube as viewed from an extension direction of the first flow path, from the first position toward the first end side of the header;
A heat exchanger according to any one of claims 1 to 4 . The cross section of the first flow path is
a shape of the heat transfer tube in a longitudinal direction thereof as viewed from an extension direction of the first flow path changes from the first position toward the first end side of the header;
A heat exchanger according to any one of claims 1 to 5 . The header
The longitudinal direction coincides with the vertical direction.
A heat exchanger according to any one of claims 1 to 6 . a plurality of heat transfer tubes (28);
a cylindrical header (30) having refrigerant flow paths (23a to 23e) connected to the plurality of heat transfer tubes formed therein;
Equipped with
The refrigerant flow path is
a first flow path (34z) extending from an inlet (34e) through which a refrigerant flows to a first end side of the header along a first direction which is the longitudinal direction of the header;
a first communication port (35z) communicating with an end of the first flow path opposite to the inlet;
a second flow path (36y) communicating with the first communication port and extending from the first communication port toward a second end of the header along the first direction;
and
The plurality of heat transfer tubes include
connected to the first flow path so as to intersect with the first direction,
The first flow path is
a refrigerant circuit including a heat exchanger in which a flow path cross-sectional area (A) at a first position (P1) is different from the flow path cross-sectional area at a second position (P2) that is a predetermined distance away from the first position toward the first end of the header ;
An operation is performed such that the quality of the refrigerant at the inlet of the heat exchanger is 0.25 or more.
Air conditioning equipment. A refrigerant circuit including the heat exchanger according to any one of claims 1 to 7 ,
The refrigerant circuit includes:
The vehicle is filled with a single refrigerant consisting of propane, CO2, and isobutane, or a mixed refrigerant containing propane, _CO2 , and isobutane.
Air conditioning equipment.