air conditioner

Abstract

To provide an air conditioner that can suppress the inflow of refrigerant into the heat exchanger as needed. [Solution] The air conditioner 1 includes a refrigerant circuit including a heat exchanger 22 having a connection part 22a through which refrigerant flows in and a connection part 22b through which refrigerant flows out, and a flow path switching valve 100. The flow path switching valve has a main body 120 in which a first space V1 is formed inside and ports 122a to 122d are provided on the internal wall surface 122, and a valve body 140 arranged in the first space and forming a first flow path R1 through which refrigerant flows. Port 122b communicates with connection part 22a, and port 122c communicates with connection part 22b. The valve body 140 switches the first flow path between a state in which port 122a and port 122b are connected, a state in which port 122a and port 122c are connected, and a state S3 in which port 122b and port 122c are connected. In each state, ports that are not connected by the first flow path are connected by a second flow path R2 formed in the first space.

Description

Technical Field

[0001] It relates to an air conditioner.

Background Art

[0002] A vapor compression type air conditioner has two heat exchangers (a radiator and an absorber) (for example, Patent Document 1 (Japanese Patent Laid-Open No. 59-170662)).

Summary of the Invention

Problems to be Solved by the Invention

[0003] In such an air conditioner, usually, the refrigerant can flow through both heat exchangers. However, depending on the situation, there may be cases where it is preferable that the refrigerant does not flow through the heat exchanger.

[0004] For example, the air conditioner of Patent Document 1 (Japanese Patent Laid-Open No. 59-170662) performs reverse cycle defrost operation. At this time, since the low-temperature refrigerant flows through the heat exchanger disposed in the air-conditioned space, although heating operation is required, there is a possibility that the heat exchanger disposed in the air-conditioned space is cooled or the air in the air-conditioned space is cooled by the refrigerant flowing through the heat exchanger disposed in the air-conditioned space during the defrost operation.

Means for Solving the Problems

[0005] The first air conditioner comprises a refrigerant circuit. In the refrigerant circuit, a compressor, a first heat exchanger, an expansion valve, and a second heat exchanger are connected by refrigerant piping. The first heat exchanger has a first connection and a second connection, which serve as the inlet and outlet for the refrigerant. The air conditioner comprises a flow path switching valve and a control device. The flow path switching valve comprises a body, a valve element, and a drive unit. A first space is formed inside the body. The wall surface forming the first space of the body is provided with a first port, a second port, a third port, and a fourth port, which serve as the inlet and outlet for the refrigerant. The valve element is positioned inside the first space. The valve element forms a first flow path through which the refrigerant flows. The drive unit drives the valve element. The control device controls the drive unit. In the first heat exchanger, refrigerant flows in from the first connection and flows out from the second connection. The second port communicates with the first connection of the first heat exchanger, and the third port communicates with the second connection of the first heat exchanger. The control unit controls the drive unit to switch the state of the valve body between a first state in which the first port and the second port are connected by a first flow path, a second state in which the first port and the third port are connected by a first flow path, and a third state in which the second port and the third port are connected by a first flow path. In the first state, the third port and the fourth port are connected by a second flow path formed in the first space, in the second state, the second port and the fourth port are connected, and in the third state, the first port and the fourth port are connected.

[0006] In the first-perspective air conditioner, the valve body of the flow path switching valve that controls the flow of refrigerant through the first heat exchanger can be set to a third state, connecting the refrigerant inlet and outlet of the first heat exchanger (in other words, a state in which the first heat exchanger is isolated from the rest of the refrigerant circuit). Therefore, in the first-perspective air conditioner, the inflow of refrigerant into the first heat exchanger can be suppressed when it is not desired for refrigerant to flow through the first heat exchanger.

[0007] The air conditioner in the second view is the air conditioner in the first view, wherein the first flow path includes an internal flow path formed inside the valve body. The internal flow path connects the first port and the second port in the first state, connects the first port and the third port in the second state, and connects the second port and the third port in the third state.

[0008] In the air conditioner from the second perspective, the internal flow path formed inside the valve body is used as the first flow path, which prevents refrigerant from flowing out of the first flow path to the outside of the first flow path, and prevents refrigerant from flowing in from outside the first flow path to the inside of the first flow path.

[0009] The third-party air conditioner is an air conditioner according to the first or second-party standards, wherein the drive unit rotates the valve body around a rotation axis to switch the state of the valve body between a first state, a second state, and a third state.

[0010] In the third-party air conditioner, a relatively simple flow path switching valve can achieve three different flow path connection states.

[0011] The air conditioner of the fourth aspect is an air conditioner of the first, second, or third aspect, wherein the inner diameter of the fourth port is smaller than the inner diameter of the first port, the inner diameter of the second port, and the inner diameter of the third port.

[0012] Because the inner diameter of the fourth port is smaller than that of the other ports, the flexibility in the placement of the fourth port can be increased. Furthermore, by reducing the diameter of the refrigerant piping that communicates with the fourth port to match the inner diameter of the fourth port, the flexibility in the piping route of the refrigerant piping connected to the flow path switching valve can be increased.

[0013] The fifth aspect of the air conditioner is an air conditioner according to any of the second, fourth, or fourth aspects, further comprising a sealing member. The sealing member is provided to surround the opening of the first port, the opening of the second port, and the opening of the third port. The sealing member seals the space between the port openings and the valve body when the first port, the second port, and the third port are connected to the internal flow path.

[0014] In the fifth aspect of the air conditioner, the sealing member prevents refrigerant from flowing out of the port connected by the internal flow path into the first space around the valve body, and prevents refrigerant from flowing in from the first space around the valve body into the port connected by the internal flow path, thereby realizing an efficient air conditioner.

[0015] The air conditioner in the sixth aspect is the same as the air conditioner in the fifth aspect, and the sizes of the sealing members provided in the first port, second port, and third port are the same.

[0016] In the sixth aspect of the air conditioner, by using a common size for the sealing member, the same sealing performance can be obtained regardless of whether the valve body is in the first, second, or third state.

[0017] The seventh aspect air conditioner is an air conditioner according to any of the first to sixth aspects, wherein the first and fourth ports are connected via a second heat exchanger through which the refrigerant flowing inside and the fluid of the heat source exchange heat, without going through a first heat exchanger. The second and third ports are connected via a first heat exchanger through which the refrigerant flowing inside and the air of the space to be air-conditioned exchange heat.

[0018] The air conditioner in the eighth perspective is the air conditioner in the seventh perspective, and the control device controls the drive unit to switch the valve body to the third state during defrost operation to defrost the second heat exchanger.

[0019] In the air conditioner described in the eighth perspective, the valve body enters the third state during defrost operation, which suppresses the occurrence of a situation where the first heat exchanger or the air in the air-conditioned space that exchanges heat with the first heat exchanger is cooled by the refrigerant when heating operation is required.

[0020] The air conditioner of the ninth aspect is an air conditioner of the seventh or eighth aspect, wherein the control device controls the drive unit so that the valve body enters the third state after a pump-down operation in which refrigerant is recovered in the second heat exchanger.

[0021] In the air conditioner described in the ninth perspective, the valve body enters a third state after the pump-down operation, thereby suppressing the inflow of refrigerant recovered on the second heat exchanger side into the first heat exchanger.

[0022] The air conditioner of the 10th perspective is an air conditioner of any of the 1st to 9th perspectives, wherein the valve body is ball-shaped, with at least a portion of its outer surface being spherical. [Brief explanation of the drawing]

[0023] [Figure 1] It is a schematic configuration diagram of an air conditioner according to an embodiment. [Figure 2] It is a schematic external view of the flow path switching valve of the air conditioner in FIG. 1. [Figure 3] It is a side view of FIG. 1 depicting the inside of the flow path switching valve. [Figure 4] It is a side view of FIG. 1 showing the inside of the flow path switching valve as seen from a direction different from that in FIG. 3. [Figure 5A] It is a view of the valve body of the flow path switching valve as seen from the side opposite to the flat surface portion of the flow path switching valve. [Figure 5B] It is a view of the valve body in FIG. 5A as seen from a direction different from that in FIG. 5A. [Figure 6A] It is a schematic diagram depicting the inside of the flow path switching valve when the state of the valve body is in the first state. [Figure 6B] It is a schematic diagram depicting the inside of the flow path switching valve when the state of the valve body is in the second state. [Figure 6C] It is a schematic diagram depicting the inside of the flow path switching valve when the state of the valve body is in the third state. [Figure 7A] It is a diagram showing the flow of refrigerant in the refrigerant circuit during cooling operation. [Figure 7B] It is a diagram showing the flow of refrigerant in the refrigerant circuit during heating operation. [Figure 7C] It is a diagram showing the flow of refrigerant in the refrigerant circuit during defrost operation.

Embodiments for Carrying Out the Invention

[0024] The air conditioner 1 according to an embodiment will be described while referring to the drawings.

[0025] (1) Overall Overview The overview of the air conditioner 1 will be described while referring to FIG. 1.

[0026] The air conditioner 1 provides cooling and heating to the interior of a house or building (the space to be air-conditioned). The air conditioner 1 mainly consists of a heat source unit 2, a utilization unit 4, and a control unit 90 (see Figure 1). In the example in Figure 1, there is one utilization unit 4, but there may be multiple utilization units 4.

[0027] As shown in Figure 1, the heat source unit 2 and the utilization unit 4 are connected by connecting pipes 6 and 8. In the air conditioner 1, the connection of the heat source unit 2 and the utilization unit 4 by connecting pipes 6 and 8 forms a refrigerant circuit 50. The refrigerant circuit 50 includes a compressor 10, a flow path switching mechanism 12, a heat source heat exchanger 14, an expansion valve 16, an accumulator 18, a liquid shut-off valve 17a, a gas shut-off valve 17b, a utilization heat exchanger 22, and a flow path switching valve 100.

[0028] The refrigerant circuit 50 is filled with a refrigerant that exhibits temperature glide, such as R454C, although this is not limited to R454C. However, the refrigerant filled in the refrigerant circuit 50 is not limited to R454C. Furthermore, the refrigerant filled in the refrigerant circuit 50 is not limited to a refrigerant that exhibits temperature glide. The refrigerant filled in the refrigerant circuit 50 can be selected as appropriate.

[0029] The flow path switching valve 100 is a device that directs the refrigerant to flow in the same direction to the heat exchanger 22 during both cooling and heating operations. Furthermore, the flow path switching valve 100 is a device that, when necessary, prevents the refrigerant from flowing to the heat exchanger 22.

[0030] (2) Detailed configuration (2-1) Heat source unit The heat source unit 2 is installed on the rooftop or in the machine room of the building where the air conditioner 1 is installed.

[0031] As shown in Figure 1, the heat source unit 2 mainly comprises a compressor 10, a flow path switching mechanism 12, a heat source heat exchanger 14, an expansion valve 16, an accumulator 18, a liquid shut-off valve 17a, a gas shut-off valve 17b, and a heat source fan 15. The various components 10, 12, 14, 16, 18, 17a, 17b, and 15 of the heat source unit 2 are housed within the casing 2a.

[0032] The suction pipe 19a connects the flow path switching mechanism 12 to the suction side of the compressor 10. An accumulator 18 is provided in the suction pipe 19a. The discharge pipe 19b connects the discharge side of the compressor 10 to the flow path switching mechanism 12. The first gas pipe 19c connects the flow path switching mechanism 12 to the gas side end of the heat source heat exchanger 14. The liquid pipe 19d connects the liquid side end of the heat source heat exchanger 14 to the liquid connecting pipe 6. An expansion valve 16 is provided in the liquid pipe 19d. A liquid shut-off valve 17a is provided at the connection between the liquid pipe 19d and the liquid connecting pipe 6. The second gas pipe 19e connects the flow path switching mechanism 12 to the gas connecting pipe 8. A gas shut-off valve 17b is provided at the connection between the second gas pipe 19e and the gas connecting pipe 8. The liquid shut-off valve 17a and the gas shut-off valve 17b are manually operated valves and are open when the air conditioner 1 is in operation.

[0033] The compressor 10 draws in low-pressure refrigerant from the refrigeration cycle through the suction pipe 19a, compresses the refrigerant using a compression mechanism (not shown), and discharges the compressed high-pressure refrigerant from the refrigeration cycle through the discharge pipe 19b. The compressor 10 is not limited to a specific type, but for example, it is a positive displacement compressor such as a rotary or scroll type. The compression mechanism of the compressor 10 is driven by a motor (not shown). The compressor 10 is an inverter compressor. However, the compressor 10 may also be a constant-speed compressor.

[0034] The flow path switching mechanism 12 switches the flow path of the refrigerant between a first circuit state and a second circuit state. In other words, the flow path switching mechanism 12 switches the destination of the refrigerant discharged from the compressor between the heat source heat exchanger 14 and the utilization heat exchanger 22. In the first circuit state, as shown by the solid line in the flow path switching mechanism 12 in Figure 1, the suction pipe 19a is connected to the second gas pipe 19e and the discharge pipe 19b is connected to the first gas pipe 19c. In the second circuit state, as shown by the dashed line in the flow path switching mechanism 12 in Figure 1, the suction pipe 19a is connected to the first gas pipe 19c and the discharge pipe 19b is connected to the second gas pipe 19e.

[0035] The flow path switching mechanism 12 is not limited to a specific type, but for example, it may be a four-way switching valve (solenoid operated valve, solenoid pilot switching valve, etc.). However, it is not limited to this, and the flow path switching mechanism 12 may also be a mechanism that has multiple solenoid valves connected to the piping and switches the flow path of the refrigerant between a first circuit state and a second circuit state by operating the multiple solenoid valves.

[0036] During cooling operation, the flow path switching mechanism 12 sets the refrigerant flow path to the first circuit state. At this time, the refrigerant discharged from the compressor 10 flows through the refrigerant circuit 50 in the following order: heat source heat exchanger 14, expansion valve 16, flow path switching valve 100, utilization heat exchanger 22, flow path switching valve 100, and returns to the compressor 10. In the first circuit state, the heat source heat exchanger 14 functions as a heat radiator (condenser), and the utilization heat exchanger 22 functions as a heat absorber (evaporator).

[0037] During heating operation, the flow path switching mechanism 12 sets the refrigerant flow path to the second circuit state. At this time, the refrigerant discharged from the compressor 10 flows through the refrigerant circuit 50 in the following order: flow path switching valve 100, utilization heat exchanger 22, flow path switching valve 100, expansion valve 16, heat source heat exchanger 14, and returns to the compressor 10. In the second circuit state, the heat source heat exchanger 14 functions as a heat absorber (evaporator), and the utilization heat exchanger 22 functions as a heat radiator (condenser).

[0038] The heat source heat exchanger 14 performs heat exchange between the refrigerant flowing inside the heat source heat exchanger 14 and the air surrounding the heat source unit 2. The heat source heat exchanger 14 is, for example, a fin-and-tube type heat exchanger having a plurality of heat transfer fins and a plurality of heat transfer tubes. Note that the substance that the refrigerant exchanges heat with in the heat source heat exchanger 14 is not limited to air, but may be a liquid such as water. If the substance that the refrigerant exchanges heat with is a liquid, then the heat source heat exchanger 14 should be of a type suitable for heat exchange between the liquid and the refrigerant.

[0039] The expansion valve 16 is a mechanism for regulating the pressure and flow rate of the refrigerant flowing through the liquid pipe 19d. The expansion valve 16 is installed in the liquid pipe 19d. The expansion valve 16 is, for example, an electrically operated valve (electronic expansion valve) with adjustable opening. However, the type of expansion valve 16 is not limited to an electrically operated valve, and may be a temperature-controlled automatic expansion valve, etc.

[0040] The accumulator 18 is a container provided in the suction pipe 19a that has a gas-liquid separation function that separates the incoming refrigerant into gaseous refrigerant and liquid refrigerant. The refrigerant flowing into the accumulator 18 is separated into gaseous refrigerant and liquid refrigerant, and the gaseous refrigerant that collects in the upper space flows into the compressor 10.

[0041] The heat source fan 15 supplies heat source air from around the heat source unit 2 to the heat source heat exchanger 14. The heat source fan 15 is not limited to any particular type of fan, but for example, it is an axial flow fan such as a propeller fan. The heat source fan 15 is driven by a motor (not shown in the figure).

[0042] The heat source unit 2 further includes a heat source control unit (not shown). The heat source control unit includes a control calculation device and a memory device. The control calculation device is a processor such as a CPU and a GPU. The memory device is a storage medium such as RAM, ROM, and flash memory. The control calculation device reads a program stored in the memory device and performs predetermined calculation processing according to the program, and in cooperation with the utilization control unit (not shown) of the utilization unit 4, controls the operation of various devices of the air conditioner 1 as the control unit 90. The functions of the control unit 90 will be described later.

[0043] (2-2) Units to use The utilization unit 4 is installed in the air-conditioned space. The utilization unit 4 may be, for example, a ceiling-mounted, ceiling-suspended, wall-mounted, or floor-standing unit.

[0044] As shown in Figure 1, the utilization unit 4 mainly comprises a utilization heat exchanger 22, a utilization fan 24, and a flow path switching valve 100. The utilization heat exchanger 22, the utilization fan 24, and the flow path switching valve 100 are housed within the housing 4a.

[0045] In the heat exchanger 22, heat exchange takes place between the refrigerant flowing inside the heat exchanger 22 and the air in the space to be air-conditioned. The heat exchanger 22 is, for example, a fin-and-tube type heat exchanger having a plurality of heat transfer fins and a plurality of heat transfer tubes.

[0046] The heat exchanger 22 has a first connection part 22a and a second connection part 22b, which serve as the inlet and outlet for the refrigerant. By switching the flow path using the flow path switching valve 100, which will be described later, refrigerant flows into the heat exchanger 22 from the first connection part 22a and flows out from the second connection part 22b, both during cooling and heating operation. By ensuring that the refrigerant flows in the same direction inside the heat exchanger 22 during both cooling and heating operation, a state can be achieved where the airflow direction formed by the fan 24 and the refrigerant flow direction are in opposition to each other during both cooling and heating operation. As a result, the heat exchange efficiency in the heat exchanger 22 can be maintained at a high level during both cooling and heating operation.

[0047] The utilization fan 24 supplies air taken in from the air-conditioned space to the utilization heat exchanger 22. The utilization fan 24 is, for example, a centrifugal fan such as a turbo fan or a sirocco fan. The utilization fan 24 is driven by a motor (not shown in the figure).

[0048] The flow path switching valve 100 switches the direction of refrigerant flow in the heat exchanger 22. Specifically, the flow path switching valve 100 controls the flow of refrigerant so that refrigerant flows in from the first connection part 22a of the heat exchanger 22 and flows out from the second connection part 22b of the heat exchanger 22, both during cooling and heating operation. Furthermore, the flow path switching valve 100 controls the flow of refrigerant so that refrigerant does not flow into the heat exchanger 22 at predetermined timings.

[0049] The outer surface of the flow path switching valve 100 is provided with a first connection part 130a, a second connection part 130b, a third connection part 130c, and a fourth connection part 130d to which piping is connected (see Figure 2). The gas connecting pipe 8 is connected to the first connection part 130a (directly or via other piping). One end of the first pipe 26a is connected to the second connection part 130b. The other end of the first pipe 26a is connected to the first connection part 22a of the heat exchanger 22. One end of the second pipe 26b is connected to the third connection part 130c. The other end of the second pipe 26b is connected to the second connection part 22b of the heat exchanger 22. The liquid connecting pipe 6 is connected to the fourth connection part 130d (directly or via other piping).

[0050] During cooling operation, the flow path switching valve 100 connects the liquid connecting pipe 6 to the first pipe 26a and the second pipe 26b to the gas connecting pipe 8 (see solid and dashed lines in the flow path switching valve 100 in Figure 7A). During heating operation, the flow path switching valve 100 connects the liquid connecting pipe 6 to the second pipe 26b and the first pipe 26a to the gas connecting pipe 8 (see solid and dashed lines in the flow path switching valve 100 in Figure 7B). When no refrigerant is flowing to the heat exchanger 22, the flow path switching valve 100 connects the gas connecting pipe 8 to the liquid connecting pipe 6 (directly via the flow path switching valve 100) and connects the first pipe 26a to the second pipe 26b (directly via the flow path switching valve 100) (see solid and dashed lines in the flow path switching valve 100 in Figure 7C).

[0051] A specific example of the structure of the flow path switching valve 100 will be described later.

[0052] The utilization unit 4 further includes a utilization control unit (not shown). The utilization control unit includes a control arithmetic unit and a memory device. The control arithmetic unit is a processor such as a CPU and a GPU. The memory device is a storage medium such as RAM, ROM, and flash memory. The control arithmetic unit reads a program stored in the memory device and performs predetermined calculation processing according to the program, and in cooperation with the heat source control unit of the heat source unit 2, controls the operation of various devices of the air conditioner 1 as the control unit 90. The functions of the control unit 90 will be described later.

[0053] (2-2-1) Details of the flow path switching valve A specific example of the structure of the flow path switching valve 100 will be explained with reference to the drawings.

[0054] As shown in Figures 2 to 4, the flow path switching valve 100 mainly comprises a main body 120, a valve body 140, a drive unit 150, a transmission unit 155, and a sealing member 160.

[0055] The main body 120 has a cylindrical shape. However, the shape of the main body 120 can be determined as appropriate and is not limited to a cylindrical shape. For example, the main body 120 may have a rectangular parallelepiped shape.

[0056] The outer surface of the main body 120 is provided with a first connecting portion 130a, a second connecting portion 130b, a third connecting portion 130c, and a fourth connecting portion 130d (see Figure 2). In this embodiment, the first connecting portion 130a and the fourth connecting portion 130d are provided on the flat surface (bottom surface) of one end of the cylindrical main body 120, and the second connecting portion 130b and the third connecting portion 130c are provided on the flat surface (bottom surface) of the other end. In this embodiment, as shown in Figure 4, the second connecting portion 130b and the third connecting portion 130c are arranged side by side in a predetermined direction (referred to as the first arrangement direction A1) on one end face of the cylindrical body 120, and the first connecting portion 130a and the fourth connecting portion 130d are arranged side by side in a second arrangement direction A2 that intersects with the first arrangement direction A1 (although not limited to this, here it is a direction perpendicular to the first arrangement direction A1, and in Figure 4 it is a direction perpendicular to the plane of the paper). Note that in Figures 6A to 6C, for the sake of clarity in understanding the drawings, the first connecting portion 130a and the fourth connecting portion 130d are depicted as being arranged in the same direction as the second connecting portion 130b and the third connecting portion 130c.

[0057] The arrangement of the first connection part 130a, the second connection part 130b, the third connection part 130c, and the fourth connection part 130d can be selected as appropriate. For example, one or all of the first connection part 130a, the second connection part 130b, the third connection part 130c, and the fourth connection part 130d may be provided on the side surface (curved surface) of the main body 120 rather than the end face. Also, for example, the second connection part 130b and the third connection part 130c may be arranged side by side along the direction of the first arrangement direction A1.

[0058] Inside the main body 120, a first space V1 is formed as shown in Figure 4. The first space V1 is the space in which the valve body 140 is housed. A second flow path R2 through which the refrigerant flows is also formed in the first space V1. A first port 122a, a second port 122b, a third port 122c, and a fourth port 122d, which serve as inlets and outlets for the refrigerant, are provided on the wall surface 122 that forms (surrounds) the first space V1. Here, the first port 122a refers to the tip of the hole facing the first space V1. The hole visible when looking at the first port 122a from the first space V1 is referred to here as the opening 122ao of the first port 122a. The same applies to the second port 122b to the fourth port 122d.

[0059] The first port 122a communicates with the first connection part 130a via a passage (not shown) formed in the main body 120. The second port 122b communicates with the second connection part 130b via a passage (not shown) formed in the main body 120. The third port 122c communicates with the third connection part 130c via a passage (not shown) formed in the main body 120. The fourth port 122d communicates with the fourth connection part 130d via a passage (not shown) formed in the main body 120.

[0060] As can be seen in Figure 1, the first port 122a, which communicates with the first connection part 130a to which the gas connecting pipe 8 is connected, and the fourth port 122d, which communicates with the fourth connection part 130d to which the liquid connecting pipe 6 is connected, are connected via a heat source heat exchanger 14, through which the refrigerant flowing inside and the fluid of the heat source exchange heat, without going through the utilization heat exchanger 22. The second port 122b, which communicates with the second connection part 130b to which the first pipe 26a is connected, and the third port 122c, which communicates with the third connection part 130c to which the second pipe 26b is connected, are connected via a utilization heat exchanger 22, through which the refrigerant flowing inside and the air in the space to be air-conditioned exchange heat.

[0061] The inner diameters of the first port 122a, the second port 122b, and the third port 122c are the same (D1) (see Figure 6B). However, this is not limited to the first port 122a, the second port 122b, and the third port 122c may be different. Although not limited to the first port 122a, the inner diameter (D2) of the fourth port 122d through which liquid refrigerant flows may be smaller than the inner diameters (D1) of the first port 122a, the second port 122b, and the third port 122c (see Figure 6B).

[0062] The valve body 140 is positioned in the first space V1 formed by the main body 120.

[0063] The valve body 140 is driven by a motor, which is an example of a drive unit 150, and rotates around the rotation axis O. In this embodiment, the rotation axis O extends in a direction perpendicular to the first arrangement direction A1 and the third arrangement direction A3 (here, the second arrangement direction A2) (see Figure 4). The first arrangement direction A1 is the direction in which the second port 122b and the third port 122c are arranged side by side. Here, the first arrangement direction A1 is also the direction in which the second connection part 130b and the third connection part 130c are arranged side by side, as described above. Note that the direction in which the second port 122b and the third port 122c are arranged and the direction in which the second connection part 130b and the third connection part 130c are arranged do not have to be the same, but if the direction in which the second port 122b and the third port 122c are arranged and the direction in which the second connection part 130b and the third connection part 130c are arranged are made to coincide, the structure of the flow path switching valve 100 can be easily simplified. The third arrangement direction A3 here is the height direction of the cylindrical body 120.

[0064] Furthermore, the drive unit 150 that rotates the valve body 140 and the shaft 146 (a shaft attached to (integrated with) the valve body 140 for the purpose of rotating the valve body 140, and supported by bearings not shown; see Figures 5A and 5B) that extends along the direction of the rotation axis O are connected by a transmission unit 155. In this embodiment, a worm gear is used as the transmission unit 155 as shown in Figure 3. However, the type of transmission mechanism used as the transmission unit 155 (the type of mechanism that transmits the force of the drive unit 150 to the shaft 146) can be selected as appropriate.

[0065] The valve body 140 is rotated by the drive unit 150 around the rotation axis O relative to the main body 120, thereby changing the flow of refrigerant within the flow path switching valve 100.

[0066] Specifically, the valve body 140 forms a first flow path R1 through which the refrigerant flows. In this embodiment, the first flow path R1 includes an internal flow path 144 formed inside the valve body 140 (surrounded by the valve body 140). When the drive unit 150 rotates the valve body 140, the port of the main body 120 that the first flow path R1 (internal flow path 144) communicates with changes, thereby causing the valve body 140 to change the flow of refrigerant within the flow path switching valve 100.

[0067] Specifically, the valve body 140 can rotate around the rotation axis O to take on a first state S1 (see Figure 6B) in which the first port 122a and the second port 122b are connected by the first flow path R1, a second state S2 (see Figure 6A) in which the first port 122a and the third port 122c are connected by the first flow path R1, and a third state S3 (see Figure 6C) in which the second port 122b and the third port 122c are connected by the first flow path R1.

[0068] Furthermore, when the valve body 140 is in the first state S1, second state S2, or third state S3, a second flow path R2 is formed outside the valve body 140 (the portion of the first space V1 where the valve body 140 is not present (around the valve body 140)).

[0069] When the valve body 140 is in the first state S1, the third port 122c and the fourth port 122d are connected by the second flow path R2 (see Figure 6B). When the valve body 140 is in the second state S2, the second port 122b and the fourth port 122d are connected by the second flow path R2 (see Figure 6A). In the example drawn in Figure 6A, the flow of refrigerant appears to be obstructed by the valve body 140, but in reality, the refrigerant flowing in from the fourth port 122d flows through the space in front of and behind the valve body 140 in a direction perpendicular to the plane of the paper, which acts as the second flow path R2, and heads towards the second port 122b. When the valve body 140 is in the third state S3, the first port 122a and the fourth port 122d are connected by the second flow path R2.

[0070] The valve body 140 is ball-shaped. Being ball-shaped means that at least a portion of the outer surface of the valve body is spherical (indicated by reference numeral 141). While the shape of the valve body 140 is not limited, it is hemispherical, with both ends in the direction of the rotation axis O being cut off in a direction perpendicular to the rotation axis O. The internal flow path 144 constituting the first flow path R1 extends through the valve body 140 in a direction intersecting (in this case perpendicular to) the rotation axis O. The spherical surface 141 of the hemispherical valve body 140, the plane 142 located on the opposite side of the spherical surface 141, and the wall surface 122 of the main body 120 form the second flow path R2.

[0071] The openings 122ao of the first port 122a, 122bo of the second port 122b, and 122co of the third port 122c, to which the internal flow path 144 (first flow path R1) of the valve body 140 is connected, may be provided with a sealing member 160 so as to surround the openings 122ao, 122bo, and 122co. The sealing member 160 is an annular member (packing). The sealing member 160 is positioned to surround the openings 122ao, 122bo, and 122co. The material of the sealing member 160 is not limited, but for example, it may be made of a fluororesin such as polytetrafluoroethylene (PTFE). When the valve body 140 rotates around the rotation axis O, the spherical surface 141 of the valve body 140 moves while sliding against the sealing member 160. The material and shape of the sealing member 160 may be selected as appropriate.

[0072] When the valve body 140 takes the first state S1 and the first port 122a and the second port 122b are connected by the internal flow path 144, the space between the opening 122ao of the first port 122a and the valve body 140 is sealed by a sealing member 160 positioned to surround the opening 122ao of the first port 122a, and the space between the opening 122bo of the second port 122b and the valve body 140 is sealed by a sealing member 160 positioned to surround the opening 122bo of the second port 122b. When the valve body 140 enters the second state S2 and the first port 122a and the third port 122c are connected by the internal flow path 144, the space between the opening 122ao of the first port 122a and the valve body 140 is sealed by a sealing member 160 positioned to surround the opening 122ao of the first port 122a, and the space between the opening 122co of the third port 122c and the valve body 140 is sealed by a sealing member 160 positioned to surround the opening 122co of the third port 122c. When the valve body 140 enters the third state S3 and the second port 122b and the third port 122c are connected by the internal flow path 144, the space between the opening 122bo of the second port 122b and the valve body 140 is sealed by a sealing member 160 positioned to surround the opening 122bo of the second port 122b, and the space between the opening 122co of the third port 122c and the valve body 140 is sealed by a sealing member 160 positioned to surround the opening 122co of the third port 122c.

[0073] Furthermore, when the valve body 140 is in the first state S1, second state S2, and third state S3, there is a timing when the openings at both ends of the internal flow path 144 are connected to all of the first port 122a, second port 122b, and third port 122c. For this reason, the size of the sealing members 160 provided at the first port 122a, second port 122b, and third port 122c may be the same so that the same sealing state can be obtained regardless of the state of the valve body 140. In particular, it is preferable that the inner diameter of the annular sealing member 160 is common to the sealing members 160 provided at the first port 122a, second port 122b, and third port 122c. Also, the sealing members 160 provided at the first port 122a, second port 122b, and third port 122c may be the same (same dimensions and same shape) member.

[0074] Furthermore, when viewing the first port 122a, the second port 122b, and the third port 122c inside the flow path switching valve 100 along the rotation axis O, at least a portion of the first port 122a is positioned between a virtual line K2 extending from the center C2 in the first arrangement direction A1 of the opening 122bo of the second port 122b to the third arrangement direction A3, and a virtual line K3 extending from the center C3 in the first arrangement direction A1 of the opening 122co of the third port 122c to the third arrangement direction A3. The third arrangement direction A3 is perpendicular to the direction in which the first arrangement direction A1 and the rotation axis O extend. More preferably, when viewing the first port 122a, the second port 122b, and the third port 122c along the axis of rotation O, at least a portion of the first port 122a is positioned between a virtual line (not shown) that passes through the center (not shown) of the opening of the sealing member 160 provided in the opening 122bo of the second port 122b in the first arrangement direction A1 and extends in the third arrangement direction A3, and a virtual line (not shown) that passes through the center (not shown) of the opening of the sealing member 160 provided in the opening 122co of the third port 122c in the first arrangement direction A1 and extends in the third arrangement direction A3.

[0075] By adopting this structure, the refrigerant can flow smoothly (without significantly changing the direction of refrigerant flow) within the flow path switching valve 100, both when the refrigerant flows from the first connection part 130a to the second connection part 130b and when the refrigerant flows from the third connection part 130c to the first connection part 130a, thereby suppressing an increase in pressure loss within the flow path switching valve 100.

[0076] In particular, preferably, the center C1 of the opening 122ao of the first port 122a in the first arrangement direction A1 is located midway between virtual lines K2 and K3 in the first arrangement direction A1. More preferably, the center of the opening of the seal member 160 provided in the opening 122ao of the first port 122a in the first arrangement direction A1 is located midway between a virtual line (not shown) that passes through the center of the opening of the seal member 160 provided in the opening 122bo of the second port 122b in the first arrangement direction A1 and extends to the third arrangement direction A3, and a virtual line (not shown) that passes through the center of the opening of the seal member 160 provided in the opening 122co of the third port 122c in the first arrangement direction A1 and extends to the third arrangement direction A3. Also, when viewed along the axis of rotation O, the axis of rotation O of the valve body 140 is located on a virtual line K1 that passes through the center C1 and extends to the third arrangement direction A3.

[0077] By adopting such a structure, the refrigerant can flow particularly smoothly within the flow path switching valve 100 when it flows from the first connection part 130a to the second connection part 130b, and when it flows from the third connection part 130c to the first connection part 130a, thereby suppressing an increase in pressure loss within the flow path switching valve 100. Furthermore, with this configuration, when viewed along the rotation axis O, the structure on the second port 122b side of the main body 120 can be made symmetrical to the structure on the third port 122c side of the main body 120, and a highly sealing structure between the opening 122bo of the second port 122b and the valve body 140, and between the opening 122co of the third port 122c and the valve body 140 can be realized relatively easily.

[0078] (2-3) Control Unit The control unit 90 consists of the heat exchanger 22 used by the heat source unit 2 and the utilization control unit 4. Note that part or all of the control unit 90 may be composed of devices provided separately from the heat source unit 2 and the utilization unit 4.

[0079] The control unit 90 controls the operation of the entire air conditioner 1 by causing the control calculation device to execute a program stored in the memory device.

[0080] As shown by the dashed lines in Figure 1, the control unit 90 is electrically connected to the utilization fan 24, the flow path switching valve 100, the compressor 10, the flow path switching mechanism 12, the expansion valve 16, and the heat source fan 15. The control unit 90 is also electrically connected to various sensors (not shown) that measure the temperature and pressure of the refrigerant, the temperature of the air in the air-conditioned space, the outside air temperature, etc. The control unit 90 controls the operation of various components of the air conditioner 1 based on control signals received by the utilization unit 4 from an operating remote control (not shown) and measurement signals from various sensors.

[0081] The control unit 90 primarily performs cooling operation, heating operation, and defrost operation.

[0082] (2-3-1) Cooling operation When the control unit 90 receives a command to perform cooling operation, for example from the operating remote control via the user unit 4, it sets the flow path switching mechanism 12 to the first circuit state, controls the drive unit 150 of the flow path switching valve 100 to set the state of the valve body 140 to the second state S2 (see Figure 6A), and starts the operation of the compressor 10. In addition, based on the measurement results of sensors that measure the temperature and pressure of the refrigerant, which are provided in the refrigerant circuit 50, it appropriately controls the rotation speed of the compressor 10 motor and the opening degree of the expansion valve 16.

[0083] The flow of refrigerant in the refrigerant circuit 50 will be explained with reference to Figure 7A. When the compressor 10 starts operating, the low-pressure gaseous refrigerant in the refrigeration cycle (hereinafter simply referred to as low-pressure) is drawn into the compressor 10 and compressed by the compressor 10's compression mechanism to become the high-pressure gaseous refrigerant in the refrigeration cycle (hereinafter simply referred to as high-pressure). The high-pressure gaseous refrigerant is sent to the heat source heat exchanger 14 via the flow path switching mechanism 12, where it exchanges heat with the air around the heat source unit 2 supplied by the heat source fan 15 and condenses to become high-pressure liquid refrigerant. The high-pressure liquid refrigerant flows through the liquid pipe 19d, passes through the expansion valve 16, and is reduced in pressure to near the suction pressure of the compressor 10, becoming a gas-liquid two-phase refrigerant. The refrigerant reduced in pressure by the expansion valve 16 is sent to the utilization unit 4 and flows into the flow path switching valve 100. The refrigerant that flows from the liquid connecting pipe 6 into the flow path switching valve 100 via the fourth connection part 130d and the fourth port 122d flows through the second flow path R2 (shown as a dashed line within the flow path switching valve 100 in Figure 7A), and flows into the utilization heat exchanger 22 from the first connection part 22a via the second port 122b, the second connection part 130b, and the first pipe 26a. The gas-liquid two-phase refrigerant that flows into the utilization heat exchanger 22 exchanges heat with the air of the air-conditioned space supplied to the utilization heat exchanger 22 by the utilization fan 24, evaporates, and becomes a low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant flowing out of the utilization heat exchanger 22 flows out from the second connection part 22b and flows into the flow path switching valve 100 from the third connection part 130c via the second pipe 26b. The refrigerant flowing into the flow path switching valve 100 flows through the internal flow path 144 of the valve body 140 (first flow path R1, shown as a solid line within the flow path switching valve 100 in Figure 7A) from the third port 122c, and flows out to the gas connecting pipe 8 via the first port 122a and the first connection part 130a. The refrigerant is then sent to the heat source unit 2 via the gas connecting pipe 8 and flows into the accumulator 18 via the flow path switching mechanism 12. The low-pressure gaseous refrigerant that flows into the accumulator 18 is then drawn back into the compressor 10. The temperature of the air supplied to the utilization heat exchanger 22 decreases by heat exchange with the refrigerant flowing through the utilization heat exchanger 22, and the cooled air is blown into the air-conditioned space.

[0084] (2-3-2) Heating operation When the control unit 90 receives a command to start heating operation, for example from the operating remote control via the user unit 4, it sets the flow path switching mechanism 12 to the second circuit state, controls the drive unit 150 of the flow path switching valve 100 to set the state of the valve body 140 to the first state S1 (see Figure 6B), and starts the operation of the compressor 10. In addition, based on the measurement results of sensors that measure the temperature and pressure of the refrigerant, which are provided in the refrigerant circuit 50, it appropriately controls the rotation speed of the compressor 10 motor and the opening degree of the expansion valve 16.

[0085] The flow of refrigerant in the refrigerant circuit 50 will be explained with reference to Figure 7B. When the compressor 10 is started, low-pressure gaseous refrigerant is drawn into the compressor 10 and compressed by the compressor 10 to become high-pressure gaseous refrigerant. The high-pressure gaseous refrigerant is sent to the utilization unit 4 via the flow path switching mechanism 12 and flows into the flow path switching valve 100. The gaseous refrigerant that has flowed into the flow path switching valve 100 from the gas connecting pipe 8 via the first connection part 130a and the first port 122a flows through the first flow path R1 (shown as a solid line in the flow path switching valve 100 in Figure 7B) and flows into the utilization heat exchanger 22 from the first connection part 22a via the second port 122b, the second connection part 130b and the first pipe 26a. The gaseous refrigerant sent to the utilization heat exchanger 22 exchanges heat with the air of the air-conditioned space supplied to the utilization heat exchanger 22 by the utilization fan 24 and condenses to become high-pressure liquid refrigerant. The temperature of the air supplied to the utilization heat exchanger 22 rises as it exchanges heat with the refrigerant flowing through the utilization heat exchanger 22, and the heated air is blown out into the space to be air-conditioned. The high-pressure liquid refrigerant flowing out from the utilization unit 4 flows out from the second connection part 22b and flows through the second pipe 26b to the flow path switching valve 100 from the third connection part 130c. The refrigerant that has flowed into the flow path switching valve 100 flows from the third port 122c to the second flow path R2 (shown as a dashed line within the flow path switching valve 100 in Figure 7B), and flows out to the liquid connecting pipe 6 via the fourth port 122d and the fourth connection part 130d. The high-pressure liquid refrigerant that has flowed out into the liquid connecting pipe 6 flows into the heat source unit 2. The refrigerant flowing into the heat source unit 2 flows through the liquid pipe 19d and, as it flows through the expansion valve 16, is reduced in pressure to near the suction pressure of the compressor 10, becoming a gas-liquid two-phase refrigerant, which then flows into the heat source heat exchanger 14. The low-pressure gas-liquid two-phase refrigerant flowing into the heat source heat exchanger 14 exchanges heat with the air surrounding the heat source unit 2 supplied by the heat source fan 15, evaporates, and becomes a low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant flows into the accumulator 18 via the flow path switching mechanism 12. The low-pressure gaseous refrigerant flowing into the accumulator 18 is then drawn back into the compressor 10.

[0086] (2-3-3) Defrost Operation When the control unit 90 determines that predetermined defrost start conditions have been met during the heating operation of the air conditioner 1, it sets the flow path switching mechanism 12 to the first circuit state and controls the drive unit 150 of the flow path switching valve 100 to set the state of the valve body 140 to the third state S3, thereby performing defrost operation. Defrost operation is performed to melt and remove frost that has accumulated on the heat source heat exchanger 14 during heating operation.

[0087] The defrost start condition is a condition under which it is desirable to defrost the heat source heat exchanger 14 when that condition is met. For example, the control unit 90 determines that the defrost start condition has been met when the refrigerant temperature measured by a temperature sensor (not shown) provided on the heat source heat exchanger 14 falls below a predetermined temperature. Alternatively, the control unit 90 may determine that the defrost start condition has been met when the duration of heating operation exceeds a predetermined time.

[0088] The control unit 90 temporarily stops the compressor 10 before starting the defrost operation. Alternatively, the control unit 90 reduces the rotational speed of the compressor 10 before starting the defrost operation. Then, at a predetermined timing, the control unit 90 sets the flow path switching mechanism 12 to the first circuit state. Also, at a predetermined timing, the control unit 90 controls the drive unit 150 of the flow path switching valve 100 to set the state of the valve body 140 to the third state S3. Then, the control unit 90 operates the compressor 10 at a predetermined rotational speed (starts the defrost operation). When the valve body 140 of the flow path switching valve 100 is in the third state S3, the refrigerant discharged by the compressor 10 flows through the heat source heat exchanger 14 and enters the flow path switching valve 100 from the liquid connecting pipe 6 via the fourth connection part 130d and the fourth port 122d. The refrigerant that flows into the flow path switching valve 100 flows through the second flow path R2 (shown as a dashed line within the flow path switching valve 100 in Figure 7C) and flows out to the gas connecting pipe 8 via the first port 122a and the first connection part 130a. When the valve body 140 of the flow path switching valve 100 is in the third state S3, no refrigerant (refrigerant whose temperature has decreased by melting frost in the heat source heat exchanger 14) flows into the utilization heat exchanger 22.

[0089] The control unit 90 does not have to stop the utilization fan 24 during defrost operation. In this case, for example, if relatively high-temperature refrigerant remains in the utilization heat exchanger 22, relatively high-temperature air can be blown into the air-conditioned space even during defrost operation. However, it is not limited to this, and the control unit 90 may stop the utilization fan 24 during defrost operation.

[0090] When the control unit 90 determines that the defrost termination condition has been met during defrost operation, it decides to terminate the defrost operation and returns to heating operation (the control unit 90 sets the flow path switching mechanism 12 to the second circuit state and controls the drive unit 150 of the flow path switching valve 100 to set the state of the valve body 140 to the first state S1). For example, the control unit 90 determines that the defrost termination condition has been met when the refrigerant temperature measured by a temperature sensor (not shown) provided on the heat source heat exchanger 14 reaches or exceeds a predetermined termination judgment temperature, and this state continues for a predetermined time or longer.

[0091] (3) Features (3-1) The air conditioner 1 includes a refrigerant circuit 50. In the refrigerant circuit 50, a compressor 10, a utilization heat exchanger 22 as an example of a first heat exchanger, an expansion valve 16, and a heat source heat exchanger 14 as an example of a second heat exchanger are connected by refrigerant piping. The utilization heat exchanger 22 has a first connection part 22a and a second connection part 22b which serve as the inlet and outlet for the refrigerant. The air conditioner 1 also includes a flow path switching valve 100 and a control unit 90 as an example of a control device. The flow path switching valve 100 includes a body 120, a valve body 140, and a drive unit 150. A first space V1 is formed inside the body 120. The wall surface 122 forming the first space V1 of the body 120 is provided with a first port 122a, a second port 122b, a third port 122c, and a fourth port 122d which serve as the inlet and outlet for the refrigerant. The valve body 140 is positioned inside the first space V1. The valve body 140 forms the first flow path R1 through which the refrigerant flows. The drive unit 150 drives the valve body 140. The control unit 90 controls the drive unit 150. In the utilization heat exchanger 22, the refrigerant flows in from the first connection part 22a and flows out from the second connection part 22b. The second port 122b communicates with the first connection part 22a of the utilization heat exchanger 22, and the third port 122c communicates with the second connection part 22b of the utilization heat exchanger 22. The control unit 90 controls the drive unit 150 to switch the state of the valve body 140 between a first state S1 in which the first port 122a and the second port 122b are connected by a first flow path R1, a second state S2 in which the first port 122a and the third port 122c are connected by a first flow path R1, and a third state S3 in which the second port 122b and the third port 122c are connected by a first flow path R1. In the first state S1, the third port 122c and the fourth port 122d are connected by a second flow path R2 formed in the first space V1, in the second state S2, the second port 122b and the fourth port 122d are connected, and in the third state S3, the first port 122a and the fourth port 122d are connected by a second flow path R2 formed in the first space V1.

[0092] In this air conditioner 1, the valve body 140 of the flow path switching valve 100, which controls the flow of refrigerant through the heat exchanger 22, can be set to a third state S3 (in other words, a state in which the heat exchanger 22 is disconnected from the rest of the refrigerant circuit 50) by connecting the refrigerant inlet and outlet of the heat exchanger 22. Therefore, in the air conditioner 1 of the first aspect, the inflow of refrigerant into the heat exchanger 22 can be suppressed when it is not desired to flow refrigerant through the heat exchanger 22.

[0093] Furthermore, by utilizing the space outside the valve body 140 (part of the first space V1) as a refrigerant flow path, a compact flow path switching valve 100 that can take on three different flow path connection states can be realized.

[0094] Furthermore, in this air conditioner 1, the connection state of three different flow paths can be switched with a single flow path switching valve 100 without using multiple valves, thereby suppressing an increase in the number of parts.

[0095] (3-2) In the air conditioner 1, the first flow path R1 includes an internal flow path 144 formed inside the valve body 140. The internal flow path 144 connects the first port 122a and the second port 122b in the first state S1, connects the first port 122a and the third port 122c in the second state S2, and connects the second port 122b and the third port 122c in the third state S3.

[0096] In this air conditioner 1, the internal flow path 144 formed inside the valve body 140 is used as the first flow path R1, so that refrigerant does not flow out of the first flow path R1 to the outside of the first flow path R1, nor does refrigerant flow into the first flow path R1 from outside of the first flow path R1.

[0097] (3-3) In the air conditioner 1, the drive unit 150 rotates the valve body 140 around the rotation axis O, switching the state of the valve body 140 between the first state S1, the second state S2, and the third state S3. Therefore, in this air conditioner 1, the flow path switching valve 100, which has a relatively simple structure, can achieve connection states for three different flow paths.

[0098] (3-4) In the air conditioner 1, the inner diameter D2 of the fourth port 122d is smaller than the inner diameter D1 of the first port 122a, the inner diameter D1 of the second port 122b, and the inner diameter D1 of the third port 122c.

[0099] In the air conditioner 1, the inner diameter D2 of the fourth port 122d is smaller than that of the other ports 122a to 122c, which increases the flexibility of the placement of the fourth port 122d. Furthermore, by reducing the diameter of the refrigerant piping that communicates with the fourth port 122d to match the inner diameter D2 of the fourth port 122d, the flexibility of the piping route of the refrigerant piping connected to the flow path switching valve 100 can be increased.

[0100] (3-5) The air conditioner 1 is equipped with a sealing member 160. The sealing member 160 is provided so as to surround the opening 122ao of the first port 122a, the opening 122bo of the second port 122b, and the opening 122co of the third port 122c. When the first port 122a, the second port 122b, and the third port 122c are connected to the internal flow path 144, the sealing member 160 seals the space between the openings 122ao, 122bo, and 122co of the ports 122a, 122b, and 122c connected by the internal flow path 144 and the valve body 140.

[0101] By providing the sealing member 160, it is possible to suppress situations in which refrigerant flows out from ports 122a, 122b, and 122c connected by the internal flow path 144 into the first space V1 around the valve body 140, or flows in from the first space V1 around the valve body 140 into ports 122a, 122b, and 122c connected by the internal flow path 144, thereby realizing an efficient air conditioner 1.

[0102] Furthermore, a sealing member 160 is not required for the fourth port 122d, which is not connected to the internal flow path 144 (first flow path R1).

[0103] (3-6) In the air conditioner 1, the size of the sealing members 160 provided in the first port 122a, the second port 122b, and the third port 122c may be the same. In particular, it is preferable that the inner diameter of the opening of the sealing member 160 provided in the first port 122a, the second port 122b, and the third port 122c be at least the same.

[0104] In the air conditioner 1, by using a common size for the sealing member 160, the same sealing performance can be obtained regardless of whether the valve body 140 is in the first state S1 to the third state S3.

[0105] (3-7) In the air conditioner 1, the first port 122a and the fourth port 122d are connected via a heat source heat exchanger 14, through which the refrigerant flowing inside and the fluid of the heat source exchange heat, without going through the utilization heat exchanger 22. The second port 122b and the third port 122c are connected via a utilization heat exchanger 22, through which the refrigerant flowing inside and the air in the space to be air-conditioned exchange heat.

[0106] The control unit 90 controls the drive unit 150 to switch the valve body 140 to the third state S3 during defrost operation to defrost the heat source heat exchanger 14.

[0107] In this air conditioner 1, when defrosting is performed, the valve body 140 enters the third state S3, which suppresses the occurrence of a situation where the heat exchanger 22 or the air in the air-conditioned space that exchanges heat with the heat exchanger 22 is cooled by the refrigerant when heating operation is required.

[0108] (4) Variations The following are variations of the above embodiment. The following variations may be combined as appropriate, as long as they do not contradict each other.

[0109] (4-1) Variation A In the above embodiment, an example was described in which the valve body 140 is controlled to the third state S3 during defrost operation. However, the timing for switching the state of the valve body 140 to the third state is not limited to defrost operation.

[0110] For example, the control unit 90 may control the drive unit 150 so that the valve body 140 enters the third state S3 after a pump-down operation to recover the refrigerant in the heat source heat exchanger 14.

[0111] Specifically, when the control unit 90 determines that a pump-down is necessary, or when the air conditioner 1 receives an instruction to perform a pump-down operation, it sets the flow path switching mechanism 12 to the first circuit state, sets the state of the valve body 140 of the flow path switching valve 100 to the first state S1, closes the expansion valve 16, and operates the compressor 10 to recover refrigerant from the utilization unit 4 to the heat source heat exchanger 14. After performing this operation for a predetermined period, the control unit 90 controls the state of the valve body 140 of the flow path switching valve 100 to the third state S3 and stops the operation of the compressor 10. This control suppresses the inflow (backflow) of refrigerant into the utilization heat exchanger 22.

[0112] (4-2) Modification B In the above embodiment, an example was described in which the valve body 140 of the flow path switching valve 100 is ball-shaped, and the state of the valve body 140 is changed by rotating the valve body 140. However, the invention is not limited to this.

[0113] For example, a flow path switching valve may have a valve body consisting of multiple plates, each having a hole that forms a first flow path R1 and a notch that forms a second flow path R2. By rotating the multiple plates around a rotation axis perpendicular to the plates, the relative positional relationship of the holes and notches of the multiple plates is changed to realize the connection state between ports through the first flow path R1 and the second flow path R2 as described above (the flow path switching valve may be of the revolver type). Alternatively, a flow path switching valve may have a valve body consisting of multiple plates, each having a hole that forms a first flow path R1 and a notch that forms a second flow path R2. By sliding the multiple plates, the relative positional relationship of the holes and notches of the multiple plates is changed to realize the connection state between ports through the first flow path R1 and the second flow path R2 as described above.

[0114] (4-3) Modification C In the above embodiment, an example was described in which the flow path switching valve 100 is provided in the utilization unit 4, but the location where the flow path switching valve 100 is installed is not limited to within the utilization unit 4. The flow path switching valve 100 may be provided in the heat source unit 2, or it may be provided separately in the connecting pipes 6 and 8 from the heat source unit 2 and the utilization unit 4.

[0115] (4-4) Modification D In the above embodiment, an example is described in which an internal flow path 144 formed inside the valve body 140 of the flow path switching valve 100 functions as the first flow path R1. However, it is not limited to this, and at least a part of the first flow path R1 may be a passage formed by the valve body 140 and the wall surface 122 of the main body 120, which is separate from the second flow path R2.

[0116] <Note> While embodiments of this disclosure have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of this disclosure as described in the claims. [Explanation of Symbols]

[0117] 1. Air conditioner 10 Compressor 14 Heat source heat exchanger (second heat exchanger) 16 Expansion valve 22 Heat exchanger used (1st heat exchanger) 22a First connection section 22b Second connection section 50 Refrigerant Circuit 90 Control Unit (Control Device) 100 Flow path switching valve 120 Main Unit 122 Wall surface 122a Port 1 122ao aperture 122b Port 2 122bo aperture 122c Port 3 122co opening 122d Port 4 140 valve body 144 Internal flow channels 150 Drive unit 160 sealing member D1 Inner diameter of the 1st port, 2nd port, and 3rd port D2 Inner diameter of the 4th port O Rotation axis R1 First channel R2 Second channel S1 First state S2 Second state S3 Third State V1 1st space [Prior art documents] [Patent Documents]

[0118] [Patent Document 1] Japanese Patent Application Publication No. 59-170662

Claims

1. An air conditioner comprising a compressor (10), a first heat exchanger (22) having a first connection part (22a) and a second connection part (22b) which serve as the inlet and outlet of the refrigerant, an expansion valve (16), and a second heat exchanger (14), all connected by refrigerant piping in a refrigerant circuit (50), A flow path switching valve (100) having a main body (120) having a first space (V1) formed inside and a first port (122a), a second port (122b), a third port (122c), and a fourth port (122d) provided on the wall surface (122) forming the first space, which serve as inlets and outlets for the refrigerant; a valve body (140) disposed inside the first space and forming a first flow path (R1) through which the refrigerant flows; and a drive unit (150) that drives the valve body. A control device (90) that controls the drive unit, Equipped with, In the first heat exchanger, the refrigerant flows in from the first connection and flows out from the second connection. The second port communicates with the first connection portion of the first heat exchanger, and the third port communicates with the second connection portion of the first heat exchanger. The control device controls the drive unit to switch the state of the valve body between a first state (S1) in which the first port and the second port are connected by the first flow path, a second state (S2) in which the first port and the third port are connected by the first flow path, and a third state (S3) in which the second port and the third port are connected by the first flow path. In the first state, the third port and the fourth port are connected by a second flow path (R2) formed in the first space; in the second state, the second port and the fourth port are connected by a second flow path (R2) formed in the first space; in the third state, the first port and the fourth port are connected by a second flow path (R2) formed in the first space. Air conditioner (1).

2. The first flow path includes an internal flow path (144) formed inside the valve body, The internal flow path connects the first port and the second port in the first state, connects the first port and the third port in the second state, and connects the second port and the third port in the third state. The air conditioner according to claim 1.

3. The drive unit rotates the valve body around the rotation axis (O) to switch the state of the valve body between the first state, the second state, and the third state. The air conditioner according to claim 1 or 2.

4. The inner diameter (D2) of the fourth port is smaller than the inner diameter (D1) of the first port, the inner diameter (D1) of the second port, and the inner diameter (D1) of the third port. The air conditioner according to claim 1 or 2.

5. The device further includes a sealing member (160) provided so as to surround the opening of the first port (122ao), the opening of the second port (122bo), and the opening of the third port (122co), which seals the space between the opening and the valve body when the first port, the second port, and the third port are connected to the internal flow path. The air conditioner according to claim 2.

6. The size of the sealing members provided in the first port, the second port, and the third port is the same. The air conditioner according to claim 5.

7. The first and fourth ports are connected via the second heat exchanger, through which the refrigerant flowing inside and the fluid of the heat source exchange heat, without going through the first heat exchanger, and the second and third ports are connected via the first heat exchanger, through which the refrigerant flowing inside and the air of the space to be air-conditioned exchange heat. The air conditioner according to claim 1 or 2.

8. The control device controls the drive unit to switch the valve body to the third state during defrost operation to defrost the second heat exchanger. The air conditioner according to claim 7.

9. The control device controls the drive unit so that the valve body enters the third state after a pump-down operation to recover the refrigerant in the second heat exchanger. The air conditioner according to claim 7.

10. The valve body is ball-shaped, with at least a portion of its outer surface being spherical. The air conditioner according to claim 1 or 2.

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