Air conditioner

Abstract

To provide an air conditioner that can realize high comfort, and is used in a house.SOLUTION: An air conditioner 1 installed in a house comprises a plurality of utilization units 50A-50D whose operations can be individually controlled, a heat source unit 10, and humidity sensors 64. The heat source unit is connected to the plurality of utilization units by communication pipes CP1 and CP2, and constitutes a refrigerant circuit 30 together with the plurality of utilization units. The humidity sensors are provided so as to correspond to the respective utilization units. In the air conditioner 1, R32 is used as a refrigerant flowing through the refrigerant circuit. In one embodiment, the utilization units are installed in at least a bedroom. In another embodiment, the utilization units are installed in at least a bathroom or a kitchen.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This relates to air conditioners used in homes. [Background technology]

[0002] Conventionally, as described in Patent Document 1 (International Publication No. 2006 / 003925), an air conditioner that uses R410A as a refrigerant and multiple utilization units whose operation can be controlled individually to provide air conditioning for office buildings and the like has been known. Summary of the Invention [Problem to be solved by the invention]

[0003] Such air conditioners with multiple utilization units that can be individually controlled may also be applied to homes. Air conditioners used in homes are required to achieve a higher level of comfort than air conditioners used in office buildings, and conventional air conditioners have room for improvement in terms of improving comfort. [Means for solving the problem]

[0004] An air conditioner according to a first aspect is installed in a residence. The air conditioner includes a plurality of utilization units, a heat source unit, and a humidity sensor. The operation of the plurality of utilization units can be controlled individually. The heat source unit is connected to the plurality of utilization units by interconnecting piping, and together with the plurality of utilization units, forms a refrigerant circuit. A humidity sensor is provided corresponding to each utilization unit. At least one utilization unit is installed in a bedroom. The air conditioner uses R32 as the refrigerant that flows through the refrigerant circuit.

[0005] In the air conditioner of the first aspect, a humidity sensor is provided for each utilization unit, so that the humidity in the space to be air-conditioned for each utilization unit can be ascertained and the humidity in each space to be air-conditioned can be optimized. In particular, in the air conditioner of the first aspect, a humidity sensor is provided for the utilization unit used in the bedroom, so that the humidity in the bedroom can be optimized and a comfortable living environment and sleeping environment can be realized.

[0006] Furthermore, the air conditioner of the first aspect uses R32 as a refrigerant. Assuming the same capacity, an air conditioner using R32 can reduce the amount of refrigerant circulated compared to an air conditioner using R410A. As a result, the air conditioner of the first aspect reduces the noise of the refrigerant passing through the piping compared to an air conditioner using R410A, achieving a quieter and more comfortable sleeping environment in the bedroom.

[0007] An air conditioner according to a second aspect is installed in a residence. The air conditioner comprises a plurality of utilization units, a heat source unit, and a humidity sensor. The operation of the plurality of utilization units can be controlled individually. The heat source unit is connected to the plurality of utilization units by interconnecting piping, and together with the plurality of utilization units, forms a refrigerant circuit. A humidity sensor is provided corresponding to each utilization unit. At least one utilization unit is installed in a bathroom or kitchen, and the air conditioner uses R32 as the refrigerant that flows through the refrigerant circuit.

[0008] In the air conditioner of the second aspect, a humidity sensor is provided for each utilization unit, so that the humidity in the space to be air-conditioned for each utilization unit can be ascertained and the humidity in each space to be air-conditioned can be optimized. In particular, in the air conditioner of the second aspect, a humidity sensor is provided for utilization units used in bathrooms or kitchens where humidity is likely to increase due to the use of hot water or steam from cooking, so that the humidity in the bathrooms or kitchens can be optimized.

[0009] An air conditioner according to a third aspect is the air conditioner according to the first aspect, wherein each utilization unit has a fan that blows air into a space to be air-conditioned. The fan of the utilization unit installed in the bedroom has a plurality of fan operation modes with different rotation speeds. The plurality of fan operation modes includes a fan operation mode for sleep, which has the smallest rotation speed among the plurality of fan operation modes.

[0010] The utilization unit of the air conditioner according to the third aspect, which is installed in a bedroom, has a fan operation mode for sleep in which the rotation speed is minimum. By using this fan operation mode while sleeping, the operating noise of the fan can be suppressed, and a comfortable sleeping environment can be achieved in the bedroom.

[0011] Furthermore, when the operating noise of the fan is suppressed, the noise of the refrigerant passing through the pipes tends to become noticeable. However, because this air conditioner uses R32 as the refrigerant, the noise of the refrigerant passing through the pipes is suppressed, creating a quiet and comfortable sleeping environment in the bedroom.

[0012] An air conditioner according to a fourth aspect is the air conditioner according to the second aspect, wherein each utilization unit has a first heat exchanger. The utilization unit installed in a bathroom or kitchen performs a dehumidifying operation in which the first heat exchanger functions as an evaporator of the refrigerant, and a drying operation in which condensation water adhering to the first heat exchanger during the dehumidifying operation is removed.

[0013] In the air conditioner of the fourth aspect, after dehumidifying the bathroom or kitchen, where humidity tends to be high, the first heat exchanger that functions as an evaporator for dehumidification is dried, thereby suppressing the occurrence of mold and odors in the user unit installed in the bathroom or kitchen.

[0014] An air conditioner of a fifth aspect is the air conditioner of any of the first to fourth aspects, wherein the heat source unit has a compressor, a suction pipe, a suction pressure sensor, and a heat source heat exchanger. Refrigerant to be drawn into the compressor flows through the suction pipe. The suction pressure sensor is provided on the suction pipe. Each utilization unit has a first heat exchanger and a first expansion device. The first expansion device is disposed between the heat source heat exchanger and the first heat exchanger in the refrigerant circuit, and adjusts the amount of refrigerant passing through the first heat exchanger. When a dehumidification operation is performed in each utilization unit, causing the first heat exchanger to function as an evaporator, the first expansion device or compressor of that utilization unit is controlled so that the evaporation temperature calculated from the detection value of the suction pressure sensor becomes a first target temperature.

[0015] In the dehumidification operation, in order to accurately control the humidity in the air-conditioned space, it is necessary to control the evaporation temperature in the first heat exchanger to a desired temperature. When the evaporation temperature in the first heat exchanger is calculated from the detection value of the suction pressure sensor provided in the suction pipe, as in the present embodiment, if the pressure loss between the suction pipe and the first heat exchanger is large, the error between the calculated evaporation temperature and the actual evaporation temperature is likely to be large.

[0016] In contrast, the air conditioner of the present disclosure uses R32 as the refrigerant, and can reduce the amount of refrigerant circulated compared to air conditioners that use R410A. As a result, in the air conditioner of the fifth aspect, the pressure loss between the suction pipe and the first heat exchanger can be kept relatively small, so the evaporation temperature can be calculated with high accuracy and the first expansion device or compressor can be appropriately controlled based on this evaporation temperature.

[0017] An air conditioner of a sixth aspect is the air conditioner of any of the first to fourth aspects, wherein the heat source unit has a compressor, a discharge pipe, a suction pipe, and a heat source heat exchanger. Refrigerant discharged from the compressor flows through the discharge pipe. Refrigerant drawn into the compressor flows through the suction pipe. Each utilization unit has a first heat exchanger, a first expansion device, a second heat exchanger, and a second expansion device. The first expansion device is disposed in the refrigerant circuit between the heat source heat exchanger and the first heat exchanger, and adjusts the amount of refrigerant passing through the first heat exchanger. The second expansion device is disposed in the refrigerant circuit between the heat source heat exchanger and the second heat exchanger, and adjusts the amount of refrigerant passing through the second heat exchanger. When a dehumidification operation is performed in each utilization unit, the second heat exchanger, which functions as a condenser, heats the air that has exchanged heat with the first heat exchanger, which functions as an evaporator.

[0018] In the air conditioner of the sixth aspect, reheat dehumidification is performed by heating the air after dehumidification by the first heat exchanger in the second heat exchanger, so that the temperature and humidity of the air-conditioned space can be finely adjusted while the humidity in the air-conditioned space is monitored by a humidity sensor, thereby providing a comfortable living environment.

[0019] An air conditioner according to a seventh aspect is the air conditioner according to the sixth aspect, wherein the heat source unit has an intake pressure sensor provided in the intake pipe. When a dehumidifying operation is performed in each utilization unit, the first expansion device or compressor of that utilization unit is controlled so that the evaporation temperature calculated from the detection value of the intake pressure sensor becomes a first target temperature.

[0020] In dehumidification operation, in order to accurately control humidity in the air-conditioned space, it is necessary to control the evaporation temperature in the first heat exchanger to a desired temperature. When the evaporation temperature in the first heat exchanger is calculated from the detection value of an intake pressure sensor provided in the intake pipe, if the pressure loss between the intake pipe and the first heat exchanger is large, the error between the calculated evaporation temperature and the actual evaporation temperature is likely to be large.

[0021] In contrast, the air conditioner of the present disclosure uses R32 as the refrigerant, and can reduce the amount of refrigerant circulated compared to air conditioners that use R410A. As a result, in the air conditioner of the seventh aspect, the pressure loss between the suction pipe and the first heat exchanger can be kept relatively small, making it possible to accurately calculate the evaporation temperature and appropriately control the first expansion device or compressor based on this evaporation temperature.

[0022] An air conditioner according to an eighth aspect is the air conditioner according to the sixth or seventh aspect, wherein the heat source unit has a discharge pressure sensor provided in the discharge pipe. When a dehumidifying operation is performed in each utilization unit, the second expansion device or compressor of that utilization unit is controlled so that the condensing temperature calculated from the detected value of the discharge pressure sensor becomes a second target temperature.

[0023] In reheat dehumidification operation, in order to accurately control the temperature in the air-conditioned space, it is necessary to control the condensing temperature in the second heat exchanger to a desired temperature. When the condensing temperature in the second heat exchanger is calculated from the detection value of a discharge pressure sensor installed in the discharge pipe, if the pressure loss between the discharge pipe and the second heat exchanger is large, the error between the calculated condensing temperature and the actual condensing temperature is likely to be large.

[0024] In contrast, the air conditioner of the present disclosure uses R32 as the refrigerant, and can reduce the amount of refrigerant circulated compared to air conditioners that use R410A. As a result, in the air conditioner of the eighth aspect, the pressure loss between the discharge pipe and the second heat exchanger can be kept relatively small, so the condensation temperature can be calculated with high accuracy and the second expansion device or compressor can be appropriately controlled based on this condensation temperature. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a schematic configuration diagram of an air conditioner according to a first embodiment. [Figure 2] FIG. 2 is a control block diagram of the air conditioner of FIG. [Figure 3] FIG. 10 is a schematic configuration diagram of an air conditioner according to a second embodiment. [Figure 4]FIG. 4 is a control block diagram of the air conditioner of FIG. 3. [Figure 5] FIG. 10 is a schematic configuration diagram of an air conditioner according to a third embodiment. [Figure 6] FIG. 6 is a control block diagram of the air conditioner of FIG. 5. [Figure 7] FIG. 10 is a schematic configuration diagram of an air conditioner according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] First Embodiment (1) Air conditioner configuration An air conditioner 1 according to a first embodiment of the present disclosure will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a schematic configuration diagram of the air conditioner 1, mainly illustrating the refrigerant circuit 30 of the air conditioner 1. Fig. 2 is a control block diagram of the air conditioner 1.

[0027] The air conditioner 1 is a vapor compression refrigeration cycle device installed in a house. The air conditioner 1 cools, dehumidifies, and heats the space inside the house.

[0028] The air conditioner 1 uses a single refrigerant, R32. In other words, the refrigerant circuit 30 is filled with a single refrigerant, R32. Here, a refrigerant containing 99% by weight or more, preferably 99.5% or more, of R32 is referred to as a single refrigerant, R32. By using a single refrigerant, the air conditioner 1 can achieve the same capacity as an air conditioner that uses R410A, even though the refrigerant circulation volume is 20% or more less than that of an air conditioner that uses the conventionally widely used R410A.

[0029] In addition, the statement "R32 is used as a refrigerant" in the claims means that a single refrigerant, R32, as defined above, is used as the refrigerant.

[0030] The air conditioner 1 mainly has a heat source unit 10 and a plurality of utilization units 50. In FIG. 1, there are four utilization units 50 indicated by the reference numerals 50A to 50D, but the number is not limited to four and may be two or more. The operation of the utilization units 50 can be controlled individually. Specifically, the utilization units 50 can be individually operated / stopped and their set temperatures can be changed.

[0031] The heat source unit 10 is installed, for example, outdoors, such as on a balcony or in a garden of a house.

[0032] Multiple utilization units 50 are installed in multiple spaces in a house. Note that, here, the description that a utilization unit 50 is installed in a space means that a utilization unit 50 exists for air conditioning that space, and the utilization unit 50 may be installed within that space or outside that space (for example, in the attic). In the example of FIG. 1, utilization unit 50A is installed in the bathroom, utilization unit 50B in the kitchen, utilization unit 50C in the living room, and utilization unit 50D in the bedroom. However, the spaces in which the utilization units 50 are installed shown here are merely examples, and utilization units 50 may be installed in spaces other than these. Note that each utilization unit 50 may air condition the entire room (air-conditioned space) to be air-conditioned, or may air condition a part of the room to be air-conditioned.

[0033] (1-1) Usage unit The utilization units 50A to 50D are connected to the heat source unit 10 via a first connection pipe CP1 and a second connection pipe CP2, and form part of the refrigerant circuit 30.

[0034] Each of the utilization units 50A to 50D mainly includes a utilization heat exchanger 52, a utilization expansion valve 54, a utilization fan 56, and a utilization control unit 90b (see FIGS. 1 and 2). Also, each of the utilization units 50A to 50D is provided with a temperature sensor 62 and a humidity sensor 64 corresponding to the utilization unit 50A to 50D (see FIG. 1).

[0035] The usage units 50A to 50D may include different types. For example, some of the usage units 50A to 50D may be wall-mounted, and the remaining usage units 50A to 50D may be ceiling-mounted. The usage units 50A to 50D may also have different capacities. However, because the usage units 50A to 50D are similar devices, in the following, to avoid duplication of explanation, the usage units 50A to 50D will not be described individually unless necessary, but will be described collectively as the usage unit 50.

[0036] (1-1-1) Heat exchanger used The utilization heat exchanger 52 provided in each utilization unit 50 is, for example, a fin-and-tube heat exchanger configured with a large number of heat transfer tubes and fins. One end (liquid side) of the utilization heat exchanger 52 is connected to the first connecting pipe CP1 via a pipe, and the other end (gas side) is connected to the second connecting pipe CP2 via a pipe. In the utilization heat exchanger 52, heat is exchanged between the refrigerant flowing inside and the air in the space to be air-conditioned. The utilization heat exchanger 52 functions as an evaporator when cooling and dehumidifying the space to be air-conditioned, and as a condenser when heating the space to be air-conditioned.

[0037] (1-1-2) Expansion valve The utilization expansion valve 54 provided in each utilization unit 50 is disposed in a pipe connecting the utilization heat exchanger 52 and the first connection pipe CP1. The utilization expansion valve 54 is disposed between the heat source heat exchanger 16 and the utilization heat exchanger 52 in the refrigerant circuit 30. The utilization expansion valve 54 is an electronic expansion valve with adjustable opening. The utilization expansion valve 54 adjusts the flow rate of the refrigerant flowing through the utilization heat exchanger 52 and expands the refrigerant passing through in accordance with its opening.

[0038] (1-1-3) Fans in use The usage fan 56 provided in each usage unit 50 is a fan that takes in air from the space to be air-conditioned and blows the air out into the space to be air-conditioned.

[0039] The utilization fan 56 supplies air to the utilization heat exchanger 52. When cooling, dehumidifying, or heating the space to be air-conditioned, the air supplied by the utilization fan 56 to the utilization heat exchanger 52 exchanges heat with the refrigerant flowing inside the utilization heat exchanger 52, and then is blown into the space to be air-conditioned.

[0040] The fan 56 preferably has a variable rotation speed so that the airflow can be switched between multiple levels (for example, three levels: weak, medium, and strong), and has multiple fan operation modes (operation modes of the fan 56 with different rotation speeds).

[0041] In particular, the utilization fan 56 of the utilization unit 50D installed in the bedroom preferably has multiple fan operation modes, and the multiple fan operation modes preferably include a sleep fan operation mode. The sleep fan operation mode is a mode in which the rotation speed of the utilization fan 56 is slower than in the other fan operation modes (the lowest rotation speed among the multiple fan operation modes). When the sleep fan operation mode is used, the rotation speed of the utilization fan 56 is slower, so the air conditioning capacity decreases, but the operating noise of the utilization fan 56 can be suppressed. Therefore, by having the utilization fan 56 of the utilization unit 50D installed in the bedroom have a sleep fan operation mode, a quiet sleeping environment can be achieved.

[0042] Furthermore, when the operating noise of the utility fan 56 is suppressed, the noise of the refrigerant passing through the piping becomes more noticeable. However, this air conditioner 1 uses a single refrigerant, R32, and can reduce the flow rate of the refrigerant through the piping compared to air conditioners that use R410A. Therefore, with this air conditioner 1, the noise of the refrigerant passing through the piping is also reduced compared to air conditioners that use R410A, creating a quieter and more comfortable sleeping environment in the bedroom.

[0043] (1-1-4) Temperature and humidity sensors The temperature sensor 62 provided in each utilization unit 50 is a sensor that measures the temperature of the air in the space to be air-conditioned of that utilization unit 50. The humidity sensor 64 provided in each utilization unit 50 is a sensor that measures the humidity of the air in the space to be air-conditioned of that utilization unit 50.

[0044] The temperature sensor 62 and the humidity sensor 64 are provided, for example, at the air inlet of the usage unit 50. However, the installation location of the temperature sensor 62 and the humidity sensor 64 is not limited to the air inlet of the usage unit 50, and the temperature sensor 62 and the humidity sensor 64 may be installed away from the usage unit 50.

[0045] (1-1-5) Usage Control Unit The usage control unit 90b provided in each usage unit 50 controls the operation of the device in that usage unit 50. The usage control unit 90b mainly includes a CPU (processor) and a memory.

[0046] The usage control unit 90b of each usage unit 50 is electrically connected to the usage expansion valve 54 and usage fan 56 of that usage unit 50. The usage control unit 90b is also electrically connected to the temperature sensor 62 and humidity sensor 64, and acquires measurement values ​​from the sensors.

[0047] The usage control units 90b of the multiple usage units 50 are communicatively connected to a heat source control unit 90a (described later) via a communication line, and together with the heat source control unit 90a, function as a control device 90 that controls the operation of the air conditioner 1. The control of the various devices of the air conditioner 1 by the control device 90 will be explained in the explanation of the operation of the air conditioner 1.

[0048] (1-2) Heat source unit The heat source unit 10 is connected to a plurality of utilization units 50A to 50D by connection pipes CP1 and CP2, and constitutes a refrigerant circuit 30 together with the plurality of utilization units 50A to 50D.

[0049] The heat source unit 10 mainly includes a compressor 12, a flow path switching mechanism 14, a heat source heat exchanger 16, a heat source expansion valve 18, an accumulator 22, a heat source fan 20, and a heat source control unit 90a. The heat source unit 10 also includes various sensors (temperature sensors and pressure sensors). The sensors included in the heat source unit 10 include a discharge pressure sensor 24 and a suction pressure sensor 26.

[0050] The compressor 12, the flow path switching mechanism 14, the heat source heat exchanger 16, the heat source expansion valve 18, and the accumulator 22 are devices that make up the refrigerant circuit 30. These devices that make up the refrigerant circuit 30 are connected within the heat source unit 10 by pipes P1 to P5 as follows.

[0051] The compressor 12 has a discharge port (not shown) through which the compressor 12 discharges the compressed refrigerant, connected to the flow path switching mechanism 14 via a discharge pipe P2. The discharge pipe P2 is provided with a discharge pressure sensor 24 that measures the pressure (discharge pressure) of the refrigerant. The compressor 12 has a suction port (not shown) through which the refrigerant to be compressed by the compressor 12 flows, connected to the flow path switching mechanism 14 via a suction pipe P1. An accumulator 22 is installed in the suction pipe P1. The suction pipe P1 is also provided with a suction pressure sensor 26 that measures the pressure (suction pressure) of the refrigerant. The flow path switching mechanism 14 and one end (gas side) of the heat source heat exchanger 16 are connected via a first gas pipe P3. The other end (liquid side) of the heat source heat exchanger 16 is connected to the first connection pipe CP1 via a liquid pipe P4. A heat source expansion valve 18 is disposed in the liquid pipe P4. The flow path switching mechanism 14 and the second connection pipe CP2 are connected via a second gas pipe P5.

[0052] (1-2-1) Compressor The compressor 12 is a device that compresses the refrigerant using a compression mechanism (not shown). The compressor 12 is a variable capacity inverter compressor. The compressor 12 compresses low-pressure gas refrigerant drawn in from a suction pipe P1 through a suction port using the compression mechanism, and discharges the high-pressure gas refrigerant obtained by the compression through a discharge port to a discharge pipe P2.

[0053] (1-2-2) Flow path switching mechanism The flow path switching mechanism 14 switches the flow path of the refrigerant in the refrigerant circuit 30 depending on the operation of the air conditioner 1. In this embodiment, the flow path switching mechanism 14 is a four-way switching valve.

[0054] During cooling or dehumidifying operation of the air conditioner 1, the flow path switching mechanism 14 switches the flow path of the refrigerant so that the refrigerant discharged from the compressor 12 is sent to the heat source heat exchanger 16. Specifically, during cooling or dehumidifying operation, the flow path switching mechanism 14 connects the suction pipe P1 to the second gas pipe P5 and connects the discharge pipe P2 to the first gas pipe P3 (see the solid lines in FIG. 1).

[0055] During heating operation of the air conditioner 1, the flow path switching mechanism 14 switches the flow path of the refrigerant so that the refrigerant discharged from the compressor 12 is sent to the utilization heat exchangers 52 of the utilization units 50A to 50D that are in operation. Specifically, during heating operation, the flow path switching mechanism 14 connects the suction pipe P1 to the first gas pipe P3 and connects the discharge pipe P2 to the second gas pipe P5 (see dashed lines in FIG. 1).

[0056] The flow path switching mechanism 14 is not limited to a four-way switching valve, but may be configured to combine a plurality of electromagnetic valves and pipes to achieve the above-described switching of the refrigerant flow path.

[0057] (1-2-3) Heat source heat exchanger The heat source heat exchanger 16 is, for example, a fin-and-tube heat exchanger configured with a large number of heat transfer tubes and fins. One end (liquid side) of the heat source heat exchanger 16 is connected to the liquid pipe P4, and the other end (gas side) is connected to the first gas pipe P3. In the heat source heat exchanger 16, heat is exchanged between the refrigerant flowing inside the heat source heat exchanger 16 and the heat source air (outdoor air in this embodiment). The heat source heat exchanger 16 functions as a condenser when cooling and dehumidifying the space to be air-conditioned, and as an evaporator when heating the space to be air-conditioned.

[0058] (1-2-4) Heat source fan The heat source fan 20 supplies heat source air (outdoor air in this embodiment) to the heat source heat exchanger 16 to promote heat exchange between the heat source air and the refrigerant in the heat source heat exchanger 16. The heat source fan 20 is a variable rotation speed fan whose rotation speed can be changed according to the desired air volume. The type of fan used as the heat source fan 20 may be selected as appropriate.

[0059] (1-2-5) Heat source expansion valve The heat source expansion valve 18 is an electronic expansion valve with adjustable opening. The heat source expansion valve 18 is disposed in the refrigerant circuit 30 between the heat source heat exchanger 16 and the utilization heat exchanger 52. The heat source expansion valve 18 adjusts the flow rate of the refrigerant flowing through the heat source heat exchanger 16 and expands the refrigerant passing through it according to its opening.

[0060] (1-2-6) Accumulator The accumulator 22 captures and stores therein the liquid refrigerant mixed in the refrigerant flowing in from the suction pipe P1, thereby suppressing the liquid refrigerant from flowing into the suction port of the compressor 12. The gas refrigerant that has flowed into the accumulator 22 passes through the accumulator 22 and flows into the suction port of the compressor 12 through the suction pipe P1.

[0061] (1-2-7) Heat source control unit The heat source control section 90a controls the operation of the devices in the heat source unit 10. The heat source control section 90a mainly includes a CPU (processor) and a memory.

[0062] The heat source control unit 90a is electrically connected to the compressor 12, the flow path switching mechanism 14, the heat source expansion valve 18, and the heat source fan 20. The heat source control unit 90a is also electrically connected to various sensors (pressure sensors and temperature sensors) installed in the heat source control unit 90a, including the discharge pressure sensor 24 and the suction pressure sensor 26, and acquires measurement data from the sensors. Furthermore, the heat source control unit 90a is communicably connected via communication lines to multiple usage control units 90b (usage control units 90b provided in each of the multiple usage units 50), and functions as a control device 90 that controls the operation of the air conditioner 1 together with the usage control units 90b.

[0063] The control of the air conditioner 1 by the control device 90 will be explained in the explanation of the operation of the air conditioner 1.

[0064] (2) Operation of the air conditioning unit The operation of the air conditioner 1 will be described below.

[0065] The air conditioner 1 performs cooling operation, dehumidifying operation, and heating operation.

[0066] When the utilization units 50 (50A to 50D) perform cooling operation and dehumidification operation, the control device 90 controls the flow path switching mechanism 14 to a piping connection state (referred to as a first state) shown by the solid line in Fig. 1. Specifically, the control device 90 controls the flow path switching mechanism 14 so that the discharge side of the compressor 12 and the gas side of the heat source heat exchanger 16 are in communication with each other, and so that the suction side of the compressor 12 and the gas side of the utilization heat exchanger 52 are in communication with each other. In other words, when the utilization units 50 perform cooling operation and dehumidification operation, the control device 90 controls the flow path switching mechanism 14 so that the discharge pipe P2 and the first gas pipe P3 are in communication with each other, and the suction pipe P1 and the second gas pipe P5 are in communication with each other.

[0067] When the utilization units 50 (50A to 50D) perform heating operation, the control device 90 controls the flow path switching mechanism 14 to a piping connection state (referred to as a second state) indicated by the dashed line in Fig. 1. Specifically, the control device 90 controls the flow path switching mechanism 14 so that the discharge side of the compressor 12 and the gas side of the utilization heat exchanger 52 communicate with each other, and so that the suction side of the compressor 12 and the gas side of the heat source heat exchanger 16 communicate with each other. In other words, when the utilization units 50 perform heating operation, the control device 90 controls the flow path switching mechanism 14 so that the discharge pipe P2 and the second gas pipe P5 communicate with each other, and the suction pipe P1 and the first gas pipe P3 communicate with each other.

[0068] (2-1) Cooling operation The cooling operation is an operation in which the measured value (temperature of the space to be air-conditioned) of the temperature sensor 62 of each utilization unit 50 is controlled to become the set temperature (target temperature).

[0069] When causing the utilization units 50 to perform cooling, the control device 90 sets the flow path switching mechanism 14 to the first state and sets the heat source expansion valve 18 to the fully open state. In addition, the control device 90 controls the rotation speed of the compressor 12 and the opening degree of the utilization expansion valve 54 of each utilization unit 50 so that the temperature detected by the temperature sensor 62 becomes the set temperature.

[0070] Next, the flow of refrigerant in the refrigerant circuit 30 will be described.

[0071] The control device 90 sets the flow path switching mechanism 14 to the first state and then operates the compressor 12. When the compressor 12 is operated, low-pressure gas refrigerant is drawn into the suction port of the compressor 12 via the suction pipe P1 and compressed by a compression mechanism (not shown) of the compressor 12 to become high-pressure gas refrigerant. The high-pressure gas refrigerant is sent to the heat source heat exchanger 16 via the discharge pipe P2, the flow path switching mechanism 14, and the first gas pipe P3. The high-pressure gas refrigerant then exchanges heat with the heat source air in the heat source heat exchanger 16, condensing it to become high-pressure liquid refrigerant. The high-pressure liquid refrigerant flowing out of the heat source heat exchanger 16 is sent to each utilization unit 50, and is decompressed in the utilization expansion valve 54 to become a two-phase gas-liquid refrigerant and flows into the utilization heat exchanger 52. The refrigerant that flows into the utilization heat exchanger 52 exchanges heat with the air in the space to be air-conditioned, which is supplied to the utilization heat exchanger 52 by the utilization fan 56, and evaporates to become a low-pressure gas refrigerant, which then flows out of the utilization heat exchanger 52. The air that has been cooled by heat exchange with the refrigerant in the utilization heat exchanger 52 is blown out from the utilization unit 50 into the space to be air-conditioned. The refrigerant that flows out of the utilization heat exchanger 52 is sent to the heat source unit 10 via the second connection pipe CP2, and flows into the accumulator 22 via the second gas pipe P5, the flow path switching mechanism 14, and the suction pipe P1, where it is separated into gas and liquid. The gas refrigerant that flows out of the accumulator 22 passes through the suction pipe P1 and is sucked again from the suction port of the compressor 12.

[0072] (2-2) Dehumidification operation The dehumidification operation is an operation for controlling the measurement value (humidity of the space to be air-conditioned) of the humidity sensor 64 of each utilization unit 50 to reach a target humidity.

[0073] When causing the utilization unit 50 to perform cooling, the control device 90 sets the flow path switching mechanism 14 to the first state and sets the heat source expansion valve 18 to the fully open state. In addition, the control device 90 controls the rotation speed of the compressor 12 and the opening degree of the utilization expansion valve 54 so that the humidity measured by the humidity sensor 64 becomes the target humidity.

[0074] Specifically, the control device 90 controls the cooling capacity of the utilization heat exchanger 52 so that the evaporation temperature in the utilization heat exchanger 52 is equal to or lower than the dew-point temperature of the indoor air. The control device 90 calculates the dew-point temperature based on the temperature detected by the temperature sensor 62 and the humidity detected by the humidity sensor 64. The control device 90 then sets a target evaporation temperature so that the evaporation temperature of the utilization heat exchanger 52 is lower than the dew-point temperature, and controls the rotation speed of the compressor 12 and the opening of the utilization expansion valve 54 so that the evaporation temperature of the refrigerant in the utilization heat exchanger 52, calculated from the measurement value of the suction pressure sensor 26, becomes the target evaporation temperature. Through this control, during dehumidification operation, moisture in the indoor air cooled by the utilization heat exchanger 52, which functions as an evaporator, condenses, thereby removing (dehumidifying) the moisture in the indoor air. The dehumidified air is blown out from the utilization unit 50 into the space to be air-conditioned.

[0075] In the present air conditioner 1, no temperature sensor is provided in the utilization heat exchanger 52. The control device 90 calculates the evaporation temperature in the utilization heat exchanger 52 based on the suction pressure measured by the suction pressure sensor .

[0076] If the pressure of the refrigerant in the utilization heat exchanger 52 is equal to the pressure of the refrigerant at the portion of the suction pipe P1 where the suction pressure sensor 26 is provided, the saturation temperature corresponding to the measurement value of the suction pressure sensor 26 becomes the evaporation temperature.

[0077] However, in reality, there are pipes etc. between the utilization heat exchanger 52 and the suction pressure sensor 26, and there is pressure loss between the two components, so there is a difference between the actual evaporation temperature in the utilization heat exchanger 52 and the saturation temperature of the refrigerant corresponding to the measurement value of the suction pressure sensor 26.

[0078] Therefore, for example, when the air conditioner 1 is installed, the correspondence relationship (hereinafter, for simplicity, simply referred to as the correspondence relationship) between the saturation temperature of the refrigerant corresponding to the measurement value of the suction pressure sensor 26 (or the pressure value measured by the suction pressure sensor 26) and the evaporation temperature of the refrigerant in the utilization heat exchanger 52 is determined, and information representing this correspondence relationship is stored in the memory or the like of the control device 90. Then, the control device 90 calculates the evaporation temperature in the utilization heat exchanger 52 from the suction pressure measured by the suction pressure sensor 26 based on the correspondence relationship stored in the memory or the like.

[0079] During dehumidification operation, it is preferable to accurately detect the evaporation temperature in the utilization heat exchanger 52. When calculating the evaporation temperature in the utilization heat exchanger 52 based on the suction pressure measured by the suction pressure sensor 26, correction is performed based on the correspondence relationship as described above, but a relatively large error may occur depending on the refrigerant flow state. However, because the present air conditioner 1 uses a single refrigerant, R32, the amount of refrigerant circulated can be reduced to achieve the same capacity compared to air conditioners using the conventionally widely used R410A. Therefore, when using refrigerant piping of the same size, the present air conditioner 1 using a single refrigerant, R32, does not experience a large pressure loss between the utilization heat exchanger 52 and the location of the suction pressure sensor 26 compared to an air conditioner using R410A. This makes it easier to accurately calculate the evaporation temperature in the utilization heat exchanger 52 based on the suction pressure measured by the suction pressure sensor 26.

[0080] Each utilization heat exchanger 52 may be provided with a temperature sensor for measuring the temperature of the refrigerant flowing through the utilization heat exchanger 52. However, in such an embodiment, the number of parts increases, leading to increased costs. Therefore, it is preferable that the evaporation temperature in the utilization heat exchanger 52 be selected based on the measurement value of the suction pressure sensor 26.

[0081] The flow of refrigerant in the refrigerant circuit 30 during dehumidifying operation is similar to the flow of refrigerant in the refrigerant circuit 30 during cooling operation, and therefore a description thereof will be omitted here.

[0082] The utilization unit 50 may perform a dehumidifying operation in which the utilization heat exchanger 52 functions as an evaporator for the refrigerant, and then a drying operation in which condensation water adhering to the utilization heat exchanger 52 during the dehumidifying operation is removed. The drying operation is, for example, an operation (blowing operation) in which the utilization fan 56 is operated without refrigerant flowing through the utilization heat exchanger 52. Alternatively, the drying operation may be an operation (heating operation) in which the utilization heat exchanger 52 is used in a condensed state. When the heating operation is used as the drying operation, R32 has a higher discharge temperature than R410A, and therefore it is easier to evaporate condensation water adhering to the utilization heat exchanger 52 than when R410A is used as the refrigerant.

[0083] In particular, it is preferable that the utilization unit 50 installed in a kitchen or a bathroom perform a dehumidifying operation in which the utilization heat exchanger 52 functions as a refrigerant evaporator, and then a drying operation in which condensation water that has adhered to the utilization heat exchanger 52 during the dehumidifying operation is removed. A kitchen is a space where humidity tends to increase due to the use of hot water and steam associated with cooking. A bathroom is also a space where humidity tends to increase due to the use of hot water and steam associated with cooking. When such a space is to be air-conditioned, a large amount of condensation water tends to adhere to the utilization heat exchanger 52 during the dehumidifying operation. In response to this, by performing a drying operation after the dehumidifying operation, the utilization unit 50 installed in a kitchen or a bathroom can suppress the occurrence of mold and odors in the utilization unit 50 installed in a kitchen or a bathroom where a large amount of condensation water tends to occur.

[0084] (2-3) Heating operation The heating operation is an operation in which the measurement value (temperature of the space to be air-conditioned) of the temperature sensor 62 of each utilization unit 50 is controlled to be the set temperature.

[0085] When causing the utilization units 50 to perform heating, the control device 90 sets the flow path switching mechanism 14 to the second state and fully opens the utilization expansion valve 54 of each utilization unit 50. In addition, the control device 90 controls the rotation speed of the compressor 12 and the opening degree of the heat source expansion valve 18 so that the temperature detected by the temperature sensor 62 becomes the set temperature.

[0086] Next, the flow of refrigerant in the refrigerant circuit 30 will be described.

[0087] The control device 90 sets the flow path switching mechanism 14 to the second state and then operates the compressor 12. When the compressor 12 operates, low-pressure gas refrigerant is drawn into the suction port of the compressor 12 via the suction pipe P1 and compressed by a compression mechanism (not shown) of the compressor 12 to become high-pressure gas refrigerant. The high-pressure gas refrigerant is sent to the utilization heat exchanger 52 via the discharge pipe P2, the flow path switching mechanism 14, and the second gas pipe P5. The high-pressure gas refrigerant then exchanges heat with the air in the utilization heat exchanger 52, condensing it into high-pressure liquid refrigerant. At this time, the air heated by heat exchange with the refrigerant in the utilization heat exchanger 52 is blown out from the utilization unit 50 into the air-conditioned space. The high-pressure liquid refrigerant flowing out of the utilization heat exchanger 52 is sent to the heat source unit 10 via the first connection pipe CP1. The refrigerant that flows into the heat source unit 10 flows through the liquid pipe P4 and is decompressed in the heat source expansion valve 18 to become a two-phase gas-liquid refrigerant, which then flows into the heat source heat exchanger 16. The refrigerant that flows into the heat source heat exchanger 16 exchanges heat with the heat source air supplied to the heat source heat exchanger 16 by the heat source fan 20, evaporating into a low-pressure gas refrigerant and flows out of the heat source heat exchanger 16. The refrigerant that flows out of the heat source heat exchanger 16 flows through the first gas pipe P3, the flow path switching mechanism 14, and the suction pipe P1 into the accumulator 22, where it is separated into gas and liquid. The gas refrigerant that flows out of the accumulator 22 passes through the suction pipe P1 and is sucked again from the suction port of the compressor 12.

[0088] (3) Features (3-1) The air conditioner 1 is installed in a residence. The air conditioner 1 includes a plurality of utilization units 50A to 50D, a heat source unit 10, and a humidity sensor 64. The operation of the plurality of utilization units 50 can be controlled individually. The heat source unit 10 is connected to the plurality of utilization units 50A to 50D by communication pipes CP1 and CP2, and constitutes a refrigerant circuit 30 together with the plurality of utilization units 50A to 50D. A humidity sensor 64 is provided corresponding to each utilization unit 50. The utilization unit 50D is installed in a bedroom. In the air conditioner 1, R32 is used as the refrigerant that flows through the refrigerant circuit 30.

[0089] In the air conditioner 1, a humidity sensor 64 is provided for each usage unit 50, so it is possible to grasp the humidity in the space to be air-conditioned for each usage unit 50 and optimize the humidity in each space to be air-conditioned. In particular, in the air conditioner 1, a humidity sensor 64 is provided for the usage unit 50D used in the bedroom, so it is possible to optimize the humidity in the bedroom and create a comfortable living and sleeping environment.

[0090] Furthermore, R32 is used as the refrigerant in the air conditioner 1. Assuming the same capacity, an air conditioner 1 that uses R32 can reduce the amount of refrigerant circulated compared to an air conditioner that uses R410A. As a result, the air conditioner 1 reduces the noise of the refrigerant passing through the piping compared to an air conditioner that uses R410A, creating a quieter and more comfortable sleeping environment in the bedroom.

[0091] (3-2) The air conditioner 1 is installed in a residence. The air conditioner 1 includes a plurality of utilization units 50A to 50D, a heat source unit 10, and a humidity sensor 64. The operation of the plurality of utilization units 50A to 50D can be controlled individually. The heat source unit 10 is connected to the plurality of utilization units 50 by communication pipes CP1 and CP2, and together with the plurality of utilization units 50, forms a refrigerant circuit 30. A humidity sensor 64 is provided corresponding to each utilization unit 50. The utilization unit 50A is installed in the bathroom, and the utilization unit 50B is installed in the kitchen. The air conditioner 1 uses R32 as the refrigerant that flows through the refrigerant circuit 30.

[0092] In the air conditioner 1, a humidity sensor 64 is provided for each utilization unit 50, so it is possible to grasp the humidity in the space to be air-conditioned for each utilization unit 50 and optimize the humidity in each space to be air-conditioned. In particular, in the air conditioner 1, a humidity sensor 64 is provided even for utilization units 50 used in bathrooms or kitchens where humidity tends to increase due to the use of hot water or steam from cooking, so it is possible to optimize the humidity in the bathroom or kitchen.

[0093] (3-3) In the air conditioner 1, each utilization unit 50 has a utilization fan 56 that blows air into the space to be air-conditioned. Preferably, the utilization fan 56 of the utilization unit 50D installed in the bedroom has multiple fan operation modes with different rotation speeds. The multiple fan operation modes include a fan operation mode for sleep, which has the smallest rotation speed among the multiple fan operation modes.

[0094] The utilization unit 50 of the air conditioner 1 installed in the bedroom has a sleep fan operation mode in which the rotation speed of the utilization fan 56 is at its minimum. By using this fan operation mode while sleeping, the operating noise of the utilization fan 56 can be suppressed, creating a comfortable sleeping environment in the bedroom.

[0095] Furthermore, when the operating noise of the utilization fan 56 is suppressed, the noise of the refrigerant passing through the piping tends to become noticeable. However, since this air conditioner 1 uses R32 as the refrigerant (which allows for a reduced amount of refrigerant circulating compared to the widely used R410A), the noise of the refrigerant passing through the piping can be suppressed, creating a quiet and comfortable sleeping environment in the bedroom.

[0096] (3-4) In the air conditioner 1, each utilization unit 50 has a utilization heat exchanger 52. The utilization units 50A, 50B installed in the bathroom and kitchen perform a dehumidifying operation in which the utilization heat exchanger 52 functions as a refrigerant evaporator, and a drying operation in which condensation water adhering to the utilization heat exchanger 52 during the dehumidifying operation is removed.

[0097] In the air conditioner 1, after dehumidifying the bathroom or kitchen where humidity tends to be high, the utilization heat exchanger 52 that functions as an evaporator for dehumidification is dried, thereby suppressing the occurrence of mold and odor in the utilization units 50A, 50B installed in the bathroom or kitchen.

[0098] Note that the dehumidifying operation and the drying operation may also be performed in the utilization units 50C and 50D that are installed in areas other than the bathroom and the kitchen.

[0099] (3-5) In the air conditioner 1, the heat source unit 10 has a compressor 12, a suction pipe P1, a suction pressure sensor 26, and a heat source heat exchanger 16. Refrigerant drawn into the compressor 12 flows through the suction pipe P1. The suction pressure sensor 26 is provided in the suction pipe P1 and measures the pressure of the refrigerant flowing through the suction pipe P1. Each utilization unit 50 has a utilization heat exchanger 52 and a utilization expansion valve 54. The utilization expansion valve 54 is disposed between the heat source heat exchanger 16 and the utilization heat exchanger 52 in the refrigerant circuit 30 and adjusts the amount of refrigerant passing through the utilization heat exchanger 52. When a dehumidification operation is performed in each utilization unit 50, causing the utilization heat exchanger 52 to function as an evaporator, the utilization expansion valve 54 or the compressor 12 of that utilization unit 50 is controlled so that the evaporation temperature calculated from the detection value of the suction pressure sensor 26 becomes a target evaporation temperature (first target temperature).

[0100] In dehumidification operation, in order to accurately control the humidity in the space to be air-conditioned, it is necessary to control the evaporation temperature in the utilization heat exchanger 52 to a desired temperature. When the evaporation temperature in the utilization heat exchanger 52 is calculated from the detection value of the suction pressure sensor 26 provided in the suction pipe P1 as in this embodiment, if the pressure loss between the suction pipe P1 and the utilization heat exchanger 52 is large, the error between the calculated evaporation temperature and the actual evaporation temperature is likely to become large.

[0101] In contrast, the air conditioner 1 uses a single refrigerant, R32, and can reduce the amount of refrigerant circulated compared to air conditioners 1 that use R410A. As a result, the air conditioner 1 can keep the pressure loss between the suction pipe P1 and the utilization heat exchanger 52 relatively small compared to when using piping of the same size as the air conditioner 1 and R410A as the refrigerant, and can accurately calculate the evaporation temperature and appropriately control the utilization expansion valve 54 or compressor 12 based on the accurately calculated evaporation temperature.

[0102] Second Embodiment (1) Air conditioner configuration An air conditioner 1A according to a second embodiment of the present disclosure will be described with reference to Figs. 3 and 4. Fig. 3 is a schematic configuration diagram of the air conditioner 1A, mainly depicting the refrigerant circuit 30A of the air conditioner 1A. The dashed arrows in Fig. 3 indicate the flow of refrigerant in the refrigerant circuit 30A during reheat dehumidification operation. Fig. 4 is a control block diagram of the air conditioner 1A.

[0103] The main difference between air conditioner 1A and air conditioner 1 is that the utilization unit 100 of air conditioner 1A performs reheat dehumidification operation. Here, the differences between air conditioner 1 and air conditioner 1A will be mainly explained, and explanations of the commonalities between air conditioner 1 and air conditioner 1A will be omitted as appropriate.

[0104] Like the air conditioner 1, the air conditioner 1A is a vapor compression refrigeration cycle device installed in a house, and performs cooling, dehumidification, and heating of the space within the house. A single refrigerant, R32, is sealed in the refrigerant circuit 30A of the air conditioner 1A.

[0105] The air conditioner 1A mainly has a heat source unit 10A and multiple utilization units 100 (100A to 100N). In Fig. 3, to simplify the illustration of the drawing, only two utilization units 100 are drawn, but the air conditioner 1A may have three or more utilization units 100. The operation of the utilization units 100 can be controlled individually.

[0106] (1-1) Heat source unit Unlike the heat source unit 10, the heat source unit 10A is connected to a plurality of utilization units 100 (100A to 100N) via three connection pipes (first connection pipe CP1, second connection pipe CP2, and third connection pipe CP3) and forms part of the refrigerant circuit 30A.

[0107] Furthermore, unlike the heat source unit 10 of the air conditioner 1, the heat source unit 10A has a branch pipe P6 that branches off from the branch point K1 of the discharge pipe P2 and is connected to the third connection pipe CP3.

[0108] The heat source unit 10A is otherwise similar to the heat source unit 10 of the first embodiment, so a description of the commonalities with the heat source unit 10 will be omitted here.

[0109] (1-2) Usage unit Unlike the air conditioner 1, the utilization units 100A to 100N are connected to the heat source unit 10A via three interconnecting pipes (first interconnecting pipe CP1, second interconnecting pipe CP2, and third interconnecting pipe CP3) and form part of the refrigerant circuit 30A.

[0110] Since the utilization units 100A to 100N are similar devices, in the following, the utilization units 100A to 100N will not be described individually unless necessary, but will be collectively described as utilization unit 100 to avoid duplication of description.

[0111] The utilization unit 100 has a first utilization heat exchanger 102, a second utilization heat exchanger 112, a first utilization expansion valve 104, a second utilization expansion valve 114, a utilization fan 120, and a utilization control unit 90b. Also, a temperature sensor 62 and a humidity sensor 64 are provided in each of the utilization units 100A to 100N corresponding to each of the utilization units 100A to 100N (see FIG. 3).

[0112] The following describes the first utilization heat exchanger 102, the second utilization heat exchanger 112, the first utilization expansion valve 104, the second utilization expansion valve 114, and the utilization fan 120. The utilization control unit 90b, the temperature sensor 62, and the humidity sensor 64 are the same as those in the first embodiment, and therefore will not be described here.

[0113] (1-2-1) First utilization heat exchanger and second utilization heat exchanger The first utilization heat exchanger 102 and the second utilization heat exchanger 112 provided in each utilization unit 100 are, for example, fin-and-tube heat exchangers configured with a large number of heat transfer tubes and fins.

[0114] One end (liquid side) of the first utilization heat exchanger 102 is connected to the first connection pipe CP1 via a pipe, and the other end (gas side) is connected to the second connection pipe CP2 via a pipe (see FIG. 3). The first utilization heat exchanger 102 exchanges heat between the refrigerant flowing inside and the air in the space to be air-conditioned. The first utilization heat exchanger 102 functions as an evaporator when cooling or dehumidifying the space to be air-conditioned, and functions as a condenser when heating the space to be air-conditioned.

[0115] The second use heat exchanger 112 is disposed downstream of the first use heat exchanger 102 in the flow of air generated by the use fan 120. One end of the second use heat exchanger 112 is connected to the third connection pipe CP3 via a pipe, and the other end is connected at a branch point K2 to a pipe that connects the first use heat exchanger 102 and the first connection pipe CP1 (see FIG. 3). The second use heat exchanger 112 exchanges heat between the refrigerant flowing inside and the air that has passed through the first use heat exchanger 102. The second use heat exchanger 112 functions as a condenser when dehumidifying and heating the space to be air-conditioned.

[0116] (1-2-2) First utilization expansion valve and second utilization expansion valve The first use expansion valve 104 provided in each usage unit 100 is disposed in a pipe connecting the first use heat exchanger 102 and the first connection pipe CP1. The first use expansion valve 104 is disposed in the refrigerant circuit 30A between the heat source heat exchanger 16 and the first use heat exchanger 102. The first use expansion valve 104 is an electronic expansion valve with adjustable opening. The first use expansion valve 104 adjusts the flow rate of the refrigerant flowing through the first use heat exchanger 102 and expands the refrigerant passing through in accordance with its opening.

[0117] The second use expansion valve 114 provided in each usage unit 100 is disposed in a pipe connecting the second use heat exchanger 112 and a branch point K2 (see FIG. 3) of a pipe connecting the first use heat exchanger 102 and the first connection pipe CP1. The second use expansion valve 114 is disposed in the refrigerant circuit 30A between the heat source heat exchanger 16 and the second use heat exchanger 112. The second use expansion valve 114 is an electronic expansion valve with adjustable opening. The second use expansion valve 114 adjusts the flow rate of the refrigerant flowing through the second use heat exchanger 112 and expands the refrigerant passing through in accordance with its opening.

[0118] (1-2-3) Fans in use The usage fan 120 provided in each usage unit 100 is a fan that takes in air from the space to be air-conditioned and blows the air out into the space to be air-conditioned.

[0119] The utilization fan 120 supplies air to the first utilization heat exchanger 102 and the second utilization heat exchanger 112. The air flow generated by the utilization fan 120 passes through the first utilization heat exchanger 102 and the second utilization heat exchanger 112 in this order, and is finally blown out into the space to be air-conditioned.

[0120] As with the utility fan 56 of the first embodiment, it is preferable that the utility fan 120 has multiple fan operation modes, and the utility fan 120 of the utility unit 100N installed in the bedroom has multiple fan operation modes, and it is preferable that the multiple fan operation modes include a fan operation mode for use during sleep.

[0121] (2) Operation of air conditioning equipment The operation of the air conditioner 1A will be described below.

[0122] The air conditioner 1A performs cooling operation, dehumidifying operation (reheat dehumidifying operation), and heating operation.

[0123] As in the first embodiment, the control device 90 controls the flow path switching mechanism 14 to the first state when the utilization unit 100 (100A to 100N) performs cooling operation and dehumidification operation, and controls the flow path switching mechanism 14 to the second state when the utilization unit 100 (100A to 100N) performs heating operation. Detailed explanations will be omitted.

[0124] (2-1) Cooling operation When the air conditioner 1A performs cooling operation, the control device 90 fully closes the second utilization expansion valve 114. As a result, no refrigerant flows through the third connection pipe CP3.

[0125] In the description of the cooling operation in the first embodiment, if the utilization heat exchanger 52 is read as the first utilization heat exchanger 102 and the utilization expansion valve 54 is read as the first utilization expansion valve 104, the description will relate to the cooling operation of the air conditioner 1A.

[0126] (2-2) Dehumidification operation (reheat dehumidification operation) The reheat dehumidification operation performed by the air conditioner 1A is an operation that controls the measurement value (humidity in the air conditioned space) of the humidity sensor 64 of each utilization unit 100 to reach the target humidity while suppressing a temperature drop in the air conditioned space.

[0127] When causing the utilization unit 100 to perform reheat dehumidification, the control device 90 sets the flow path switching mechanism 14 to the first state and sets the heat source expansion valve 18 to the fully open state. The control device 90 also controls the rotation speed of the compressor 12 and the opening degree of the first utilization expansion valve 104 so that the humidity measured by the humidity sensor 64 becomes the target humidity. The control device 90 also controls the rotation speed of the compressor 12 and the opening degree of the second utilization expansion valve 114 so that the temperature measured by the temperature sensor 62 becomes the target temperature.

[0128] Specifically, the control device 90 controls the cooling capacity of the first use heat exchanger 102 so that the evaporation temperature in the first use heat exchanger 102 is equal to or lower than the dew point temperature of the indoor air. The control device 90 calculates the dew point temperature based on the temperature detected by the temperature sensor 62 and the humidity detected by the humidity sensor 64. The control device 90 then sets a target evaporation temperature so that the evaporation temperature of the first use heat exchanger 102 is lower than the dew point temperature, and controls the rotation speed of the compressor 12 and the opening degree of the first use expansion valve 104 so that the evaporation temperature of the refrigerant in the first use heat exchanger 102 calculated from the measurement value of the suction pressure sensor 26 becomes the target evaporation temperature. Through such control, in the dehumidification operation (reheat dehumidification operation), moisture in the indoor air cooled by the first use heat exchanger 102 functioning as an evaporator condenses, thereby removing (dehumidifying) moisture from the indoor air. The dehumidified air is supplied to the second use heat exchanger 112.

[0129] Furthermore, the control device 90 controls the heating capacity of the second use heat exchanger 112 so that the temperature of the air blown out from the utilization unit 100 into the space to be air-conditioned becomes a target temperature. The control device 90 sets a target condensing temperature so that the desired heating capacity is obtained in the second use heat exchanger 112, and controls the rotation speed of the compressor 12 and the opening of the second use expansion valve 114 so that the condensing temperature of the refrigerant in the second use heat exchanger 112 calculated from the measurement value of the discharge pressure sensor 24 becomes the target condensing temperature. As a result, the air cooled and dehumidified in the first use heat exchanger 102 functioning as an evaporator is heated (reheated) and then blown out from the utilization unit 100 into the space to be air-conditioned.

[0130] In the air conditioner 1A, no temperature sensors are provided in the first utilization heat exchanger 102 or the second utilization heat exchanger 112. The control device 90 calculates the evaporation temperature in the first utilization heat exchanger 102 based on the suction pressure measured by the suction pressure sensor 26, and calculates the condensation temperature in the second utilization heat exchanger 112 based on the discharge pressure measured by the discharge pressure sensor 24.

[0131] The calculation of the evaporation temperature in the first utilization heat exchanger 102 based on the suction pressure measured by the suction pressure sensor 26 is similar to the calculation of the evaporation temperature in the utilization heat exchanger 52 based on the suction pressure measured by the suction pressure sensor 26 in the first embodiment.

[0132] The calculation of the condensing temperature in the second utilization heat exchanger 112 based on the discharge pressure measured by the discharge pressure sensor 24 will be described. If the pressure of the refrigerant in the second utilization heat exchanger 112 is equal to the pressure of the refrigerant at the portion of the discharge pipe P2 where the discharge pressure sensor 24 is provided, the saturation temperature corresponding to the measurement value of the discharge pressure sensor 24 becomes the condensation temperature.

[0133] However, in reality, there are pipes etc. between the second utilization heat exchanger 112 and the discharge pressure sensor 24, and there is a pressure loss between the two components, so there is a difference between the actual condensation temperature in the second utilization heat exchanger 112 and the saturation temperature of the refrigerant corresponding to the measurement value of the discharge pressure sensor 24.

[0134] Therefore, for example, when the air conditioner 1 is installed, the correspondence relationship (hereinafter, for simplicity, simply referred to as the correspondence relationship) between the saturation temperature of the refrigerant corresponding to the measurement value of the discharge pressure sensor 24 (or the pressure value measured by the discharge pressure sensor 24) and the condensation temperature of the refrigerant in the second utilization heat exchanger 112 is grasped, and information representing this correspondence relationship is stored in the memory or the like of the control device 90. Then, the control device 90 calculates the condensation temperature in the second utilization heat exchanger 112 from the discharge pressure measured by the discharge pressure sensor 24 based on the correspondence relationship stored in the memory or the like.

[0135] In reheat dehumidification operation, it is preferable to accurately detect the evaporation temperature in the first utilization heat exchanger 102 and the condensation temperature in the second utilization heat exchanger 112. When calculating the evaporation temperature in the first utilization heat exchanger 102 based on the suction pressure measured by the suction pressure sensor 26, and when calculating the condensation temperature in the second utilization heat exchanger 112 based on the discharge pressure measured by the discharge pressure sensor 24, correction is performed based on the correspondence relationship as described above, but relatively large errors may occur depending on the refrigerant flow state. However, as explained in the first embodiment, in this air conditioner 1 using a single refrigerant, R32, the amount of refrigerant circulated can be reduced compared to air conditioners using the conventionally widely used R410A refrigerant to achieve the same capacity. Therefore, when using refrigerant piping of the same size, compared to an air conditioner that uses R410A, in this air conditioner 1 that uses a single refrigerant, R32, the pressure loss between the first utilization heat exchanger 102 and the installation location of the suction pressure sensor 26, and the pressure loss between the second utilization heat exchanger 112 and the installation location of the discharge pressure sensor 24 are less likely to be large, and the values ​​of the evaporation temperature and condensation temperature can be more accurately calculated.

[0136] Each utilization heat exchanger 102, 112 may be provided with a temperature sensor for measuring the temperature of the refrigerant flowing through the utilization heat exchanger 102, 112. However, in such an embodiment, the number of parts increases, leading to increased costs. Therefore, it is preferable that the evaporation temperature and condensation temperature in the utilization heat exchanger 102, 112 be calculated based on the measurement values ​​of the suction pressure sensor 26 and the discharge pressure sensor 24.

[0137] The flow of refrigerant in the refrigerant circuit 30A during the dehumidifying and reheating operation will be described.

[0138] The control device 90 sets the flow path switching mechanism 14 to the first state and then operates the compressor 12. When the compressor 12 operates, low-pressure gas refrigerant is drawn into the suction port of the compressor 12 via the suction pipe P1 and compressed by a compression mechanism (not shown) of the compressor 12 to become high-pressure gas refrigerant. A portion of the high-pressure gas refrigerant is sent to the heat source heat exchanger 16 via the discharge pipe P2, the flow path switching mechanism 14, and the first gas pipe P3, and the remaining high-pressure gas refrigerant branches from the discharge pipe P2 at the branch point K1, flows into the branch pipe P6, and flows into the utilization unit 100 via the third connection pipe CP3.

[0139] The high-pressure gas refrigerant sent to the heat source heat exchanger 16 condenses into high-pressure liquid refrigerant by exchanging heat with the heat source air in the heat source heat exchanger 16. The high-pressure liquid refrigerant flowing out from the heat source heat exchanger 16 is sent to each utilization unit 100 via the first connection pipe CP1.

[0140] The refrigerant that flows into the utilization unit 100 through the third connecting pipe CP3 flows into the second utilization heat exchanger 112 of the utilization unit 100, where it undergoes heat exchange with the indoor air taken in by the utilization fan 120, condenses, and passes through the first utilization heat exchanger 102 to heat (reheat) the air that is supplied.

[0141] The refrigerant after exchanging heat with the air in the second use heat exchanger 112 passes through the second use expansion valve 114 and merges with the refrigerant flowing from the heat source unit 10A through the first communication pipe CP1 into the utilization unit 100 at branch point K2 in Fig. 1. The merged refrigerant passes through the first use expansion valve 104 of the utilization unit 100 and enters the first use heat exchanger 102. The refrigerant that has flowed into the first use heat exchanger 102 exchanges heat with indoor air taken in by the utilization fan 120 in the first use heat exchanger 102, thereby cooling the air in the air-conditioned space and, as a result, dehumidifying the air in the air-conditioned space. The refrigerant after exchanging heat with the air in the air-conditioned space in the first use heat exchanger 102 flows through the second communication pipe CP2 and is sent to the heat source unit 10A, passes through the second gas pipe P5, the flow path switching mechanism 14, and the suction pipe P1, and flows into the accumulator 22, where it is separated into gas and liquid. The gas refrigerant flowing out of the accumulator 22 passes through the suction pipe P1 and is sucked into the compressor 12 from the suction port again.

[0142] After performing the reheat dehumidification operation, the usage unit 100 may perform a drying operation to remove condensation water that has adhered to the first usage heat exchanger 102 during the dehumidification operation. The drying operation is, for example, an operation (blowing operation) in which the usage fan 120 is operated without refrigerant flowing through the first usage heat exchanger 102. Alternatively, the drying operation may be an operation (heating operation) in which the first usage heat exchanger 102 is used in a condensed state.

[0143] In particular, it is preferable that the utilization unit 100 installed in a kitchen or bathroom performs a dehumidifying operation in which the first utilization heat exchanger 102 functions as a refrigerant evaporator, and then a drying operation in which condensation water adhering to the first utilization heat exchanger 102 during the dehumidifying operation is removed.

[0144] The reason for performing the drying operation and the effects obtained by performing the drying operation are the same as those described in the first embodiment.

[0145] (2-3) Heating operation When causing the utilization units 100 to perform heating, the control device 90 sets the flow path switching mechanism 14 to the second state and fully opens the utilization expansion valves 104, 114 of each utilization unit 100. In addition, the control device 90 controls the rotation speed of the compressor 12 and the opening degree of the heat source expansion valve 18 so that the temperature detected by the temperature sensor 62 becomes the set temperature.

[0146] The flow of refrigerant in the refrigerant circuit 30A during heating operation will be briefly described.

[0147] The control device 90 sets the flow path switching mechanism 14 to the second state and then operates the compressor 12. When the compressor 12 operates, low-pressure gas refrigerant is drawn into the suction port of the compressor 12 via the suction pipe P1 and compressed by a compression mechanism (not shown) of the compressor 12 to become high-pressure gas refrigerant. A portion of the high-pressure gas refrigerant flows to the first utilization heat exchanger 102 of the utilization unit 100 via the discharge pipe P2, the flow path switching mechanism 14, the second gas pipe P5, and the first connecting pipe CP1, and the remainder of the high-pressure gas refrigerant flows to the second utilization heat exchanger 112 of the utilization unit 100 via the discharge pipe P2, the branch pipe P6, and the third connecting pipe CP3. The refrigerant that has flowed into the first utilization heat exchanger 102 of the utilization unit 100 exchanges heat with air in the air-conditioned space taken in by the utilization fan 120 in the first utilization heat exchanger 102, thereby heating the air in the air-conditioned space. The air heated by the first utilization heat exchanger 102 passes through the second utilization heat exchanger 112, which is disposed downstream of the first utilization heat exchanger 102 in the direction of the airflow generated by the utilization fan 120. The refrigerant that has flowed into the second utilization heat exchanger 112 further heats the air heated by the first utilization heat exchanger 102 in the second utilization heat exchanger 112.

[0148] The refrigerant that has exchanged heat with the air in the space to be air-conditioned in the first use heat exchanger 102 passes through the first use expansion valve 104. The refrigerant that has exchanged heat with the air in the space to be air-conditioned in the second use heat exchanger 112 passes through the second use expansion valve 114. The refrigerant that has passed through the first use expansion valve 104 and the refrigerant that has passed through the second use expansion valve 114 join together and flow through the first connection piping CP1 toward the heat source unit 10A. The refrigerant that has flowed into the heat source unit 10 flows through the liquid pipe P4 and is decompressed in the heat source expansion valve 18 to become a two-phase gas-liquid refrigerant and flows into the heat source heat exchanger 16. The refrigerant that has flowed into the heat source heat exchanger 16 exchanges heat with the heat source air supplied to the heat source heat exchanger 16 by the heat source fan 20, thereby evaporating and becoming a low-pressure gas refrigerant, and then flows out of the heat source heat exchanger 16. The refrigerant flowing out from the heat source heat exchanger 16 passes through the first gas pipe P3, the flow path switching mechanism 14, and the suction pipe P1 and flows into the accumulator 22, where it is separated into gas and liquid. The gas refrigerant flowing out from the accumulator 22 passes through the suction pipe P1 and is sucked again from the suction port of the compressor 12.

[0149] (3) Features (3-1) The air conditioner 1A is installed in a residence. The air conditioner 1A comprises a plurality of utilization units 100A-100N, a heat source unit 10A, and a humidity sensor 64. The operation of the plurality of utilization units 100A-100N can be controlled individually. The heat source unit 10A is connected to the plurality of utilization units 100A-100N by communication pipes CP1-CP3, and constitutes a refrigerant circuit 30 together with the plurality of utilization units 100A-100N. A humidity sensor 64 is provided corresponding to each utilization unit 100. In the air conditioner 1A, R32 is used as the refrigerant that flows through the refrigerant circuit 30A.

[0150] Of the multiple usage units 100A to 100N, usage unit 100N is installed in a bedroom. Also, of the multiple usage units 100A to 100N, usage unit 100A is installed in a bathroom. By having this configuration, the air conditioner 1A achieves the same effects as those described in (3-1) and (3-2) of feature (3) of the first embodiment.

[0151] (3-2) In the air conditioner 1A, the utilization fan 120 of the utilization unit 100N installed in the bedroom preferably has a plurality of fan operation modes with different rotation speeds, including a fan operation mode for sleep, which has the smallest rotation speed among the plurality of fan operation modes.

[0152] The utilization unit 100 installed in the bedroom of the air conditioner 1A has a sleep fan operation mode in which the rotation speed of the utilization fan 120 is at its minimum. By using this fan operation mode while sleeping, the operating noise of the utilization fan 120 is suppressed, creating a comfortable sleeping environment in the bedroom. Furthermore, because this air conditioner 1A uses a single refrigerant, R32 (which allows for a lower refrigerant circulation volume compared to the widely used R410A), the noise of the refrigerant passing through the piping is suppressed, creating a quiet and comfortable sleeping environment in the bedroom.

[0153] (3-3) In the air conditioner 1A, the utilization unit 100A installed in the bathroom and the utilization unit installed in the kitchen perform a dehumidification operation in which the first utilization heat exchanger 102 functions as a refrigerant evaporator, and a drying operation in which condensation water adhering to the first utilization heat exchanger 102 during the dehumidification operation is removed.

[0154] In the air conditioner 1A, after dehumidifying the bathroom or kitchen where humidity tends to be high, the first utilization heat exchanger 102 that functions as an evaporator for dehumidification is dried, thereby suppressing the occurrence of mold and odor in the utilization unit 100 installed in the bathroom or kitchen.

[0155] It should be noted that the dehumidifying operation and the drying operation may also be performed in the utilization units 100 installed in areas other than the bathroom and the kitchen.

[0156] (3-4) In the air conditioner 1A, the heat source unit 10A has a compressor 12, a discharge pipe P2, a suction pipe P1, and a heat source heat exchanger 16. Refrigerant discharged from the compressor 12 flows through the discharge pipe P2. Refrigerant sucked into the compressor 12 flows through the suction pipe P1. Each of the usage units 100A to 100N has a first usage heat exchanger 102 as an example of a first heat exchanger, a first usage expansion valve 104 as an example of a first expansion device, a second usage heat exchanger 112 as an example of a second heat exchanger, and a second usage expansion valve 114 as an example of a second expansion device. The first usage expansion valve 104 is disposed between the heat source heat exchanger 16 and the first usage heat exchanger 102 in the refrigerant circuit 30A, and adjusts the amount of refrigerant passing through the first usage heat exchanger 102. The second utilization expansion valve 114 is disposed between the heat source heat exchanger 16 and the second utilization heat exchanger 112 in the refrigerant circuit 30A, and adjusts the amount of refrigerant passing through the second utilization heat exchanger 112. When a dehumidification operation is performed in each utilization unit 100, in that utilization unit 100, the air that has exchanged heat with the first utilization heat exchanger 102 that functions as an evaporator is heated by the second utilization heat exchanger 112 that functions as a condenser.

[0157] In the air conditioner 1A, reheat dehumidification is performed by heating the air after dehumidification by the first utilization heat exchanger 102 in the second utilization heat exchanger 112. Therefore, the humidity in the air-conditioned space can be monitored by the humidity sensor 64, and the temperature and humidity in the air-conditioned space can be precisely adjusted, providing a comfortable living environment.

[0158] (3-5) In the air conditioner 1A, the heat source unit 10A has an intake pressure sensor 26 provided in the intake pipe P1. When a dehumidifying operation is performed in each utilization unit 100, the first utilization expansion valve 104 or the compressor 12 of that utilization unit 100 is controlled so that the evaporation temperature calculated from the detection value of the intake pressure sensor 26 becomes the target evaporation temperature (first target temperature).

[0159] In dehumidification operation, in order to accurately control the humidity in the space to be air-conditioned, it is necessary to control the evaporation temperature in the first utilization heat exchanger 102 to a desired temperature. When the evaporation temperature in the first utilization heat exchanger 102 is calculated from the detection value of the suction pressure sensor 26 provided in the suction pipe P1, if the pressure loss between the suction pipe P1 and the first utilization heat exchanger 102 is large, the error between the calculated evaporation temperature and the actual evaporation temperature is likely to become large.

[0160] In contrast, the air conditioner 1A uses a single refrigerant, R32, and can reduce the amount of refrigerant circulated compared to air conditioners that use R410A. As a result, the air conditioner 1A can keep the pressure loss between the suction pipe P1 and the first utilization heat exchanger 102 relatively small, so it can accurately calculate the evaporation temperature and appropriately control the first utilization expansion valve 104 or the compressor 12 based on this evaporation temperature.

[0161] (3-6) In the air conditioner 1A, the heat source unit 10A has a discharge pressure sensor 24 provided in the discharge pipe P2. When a dehumidifying operation is performed in each utilization unit 100, the second utilization expansion valve 114 or the compressor 12 of that utilization unit 100 is controlled so that the condensation temperature calculated from the detection value of the discharge pressure sensor 24 becomes the target condensation temperature (second target temperature).

[0162] In the reheat dehumidification operation, in order to accurately control the temperature in the space to be air-conditioned, it is necessary to control the condensing temperature in the second utilization heat exchanger 112 to a desired temperature. When the condensing temperature in the second utilization heat exchanger 112 is calculated from the detection value of the discharge pressure sensor 24 provided in the discharge pipe P2, if the pressure loss between the discharge pipe P2 and the second utilization heat exchanger 112 is large, the error between the calculated condensing temperature and the actual condensing temperature is likely to become large.

[0163] In contrast, the air conditioner 1A uses R32 as the refrigerant, and can reduce the amount of refrigerant circulated compared to air conditioners that use R410A. As a result, the air conditioner 1A can keep the pressure loss between the discharge pipe P2 and the second utilization heat exchanger 112 relatively small, so it can accurately calculate the condensation temperature and appropriately control the second utilization expansion valve 114 or the compressor 12 based on this condensation temperature.

[0164] Third Embodiment FIG. 5 shows an air conditioner 1B according to a third embodiment. The configuration of the air conditioner 1B of this embodiment overlaps in part with the configuration of the air conditioner 1A of the second embodiment. Therefore, in the description of the third embodiment, the same components as those in the second embodiment are denoted by the same reference numerals. Also, the following description will focus mainly on the differences between the third embodiment and the second embodiment.

[0165] As shown in Fig. 5, the heat source unit 10B of the air conditioner 1B has the same configuration as the heat source unit 10A of the air conditioner 1A, and further includes a branch pipe P7, a branch pipe P8, a throttle 29, and a four-way switching valve 28. As shown in Fig. 5, the branch pipe P7 branches off from a branch point K3 of the suction pipe P1. As shown in Fig. 5, the branch pipe P8 branches off from a branch point K4 of the branch pipe P7. The throttle 29 is provided in the branch pipe P8.

[0166] The four-way switching valve 28 connects the third connecting pipe CP3, the branch pipe P6, the branch pipe P7, and the branch pipe P8, and switches between a first switching state and a second switching state. In the first switching state, the four-way switching valve 28 connects the third connecting pipe CP3 and the branch pipe P6, and also connects the branch pipe P7 and the branch pipe P8, forming a loop circuit. In the second switching state, the four-way switching valve 28 connects the third connecting pipe CP3 and the branch pipe P7, and also connects the branch pipe P6 and the branch pipe P8. By introducing oil accumulated in the four-way switching valve 28 into the circuit and separating and recovering it, it is possible to prevent the four-way switching valve 28 from malfunctioning due to oil accumulation. From the viewpoint of preventing the four-way switching valve 28 from malfunctioning, it is preferable that the throttle 29 be a capillary tube.

[0167] The air conditioner 1B of this embodiment can be switched between a first mode, a second mode, a third mode, and a fourth mode by the control device 90. In the first mode, the flow path switching mechanism 14 is controlled to the second state, and the four-way switching valve 28 is switched to the first switching state. In the second mode, the flow path switching mechanism 14 is controlled to the first state, and the four-way switching valve 28 is switched to the second switching state. In the third mode, the flow path switching mechanism 14 is controlled to the first state, and the four-way switching valve 28 is switched to the first switching state. In the fourth mode, the flow path switching mechanism 14 is controlled to the first state, and the four-way switching valve 28 is switched to the second switching state. Furthermore, in the fourth mode, the operation of the utility fan 120 is stopped.

[0168] The operation performed by the air conditioner 1B of this embodiment in the first mode is the same as the heating operation performed by the air conditioner 1A of the second embodiment. The operation performed by the air conditioner 1B of this embodiment in the third mode is the same as the dehumidifying operation (dehumidifying reheating operation) performed by the air conditioner 1A of the second embodiment. The flow of refrigerant through the refrigerant circuit 30B is the same in the operation performed by the air conditioner 1B of this embodiment in the second mode (cooling operation) and the operation performed in the fourth mode (second defrosting operation). Here, the operation in the second mode by the air conditioner 1B of this embodiment (an explanation of how the refrigerant flows through the refrigerant circuit 30B) will be explained with reference to FIG. 5, and an explanation of the operation in the fourth mode will be omitted.

[0169] In the second mode, the control device 90 of the air conditioner 1B controls the flow path switching mechanism 14 to the first state and sets the four-way switching valve 28 to the second switching state. This connects the first connecting pipe CP1 to the discharge pipe P2, the second connecting pipe CP2 to the suction pipe P1, and the third connecting pipe CP3 to the branch pipe P7. When the control device 90 operates the compressor 12 in this state, the refrigerant discharged from the compressor 12 flows to the heat-source heat exchanger 16. The refrigerant condenses after heat exchange with the heat-source air taken in by the heat-source fan 20 in the heat-source heat exchanger 16, and then flows through the heat-source expansion valve 18 to the utilization unit 100. The refrigerant that flows into the utilization unit 100 is split at branch point K2 (see FIG. 5), and a portion passes through the first utilization expansion valve 104 and flows into the first utilization heat exchanger 102, while the remainder passes through the second utilization expansion valve 114 and flows into the second utilization heat exchanger 112. In the first utilization heat exchanger 102, the refrigerant exchanges heat with the air in the space to be air-conditioned that has been taken in by the utilization fan 120, and evaporates by cooling the air in the space to be air-conditioned. Furthermore, in the second utilization heat exchanger 112, the refrigerant flowing therethrough cools the air that has been cooled in the first utilization heat exchanger 102 and evaporates. The air that has been cooled by the first utilization heat exchanger 102 and the second utilization heat exchanger 112 is blown out from the utilization unit 100 into the space to be air-conditioned.

[0170] The refrigerant that flows out of the first utilization heat exchanger 102 flows through the second connection pipe CP2, and the refrigerant that flows out of the second utilization heat exchanger 112 flows through the third connection pipe CP3, each flowing toward the heat source unit 10B. The refrigerant flowing through the second connection pipe CP2 and the third connection pipe CP3 join at branch point K3 in Figure 4 and flow into the accumulator 22 where it is separated into gas and liquid. The gas refrigerant that flows out of the accumulator 22 passes through the suction pipe P1 and is sucked again from the suction port of the compressor 12.

[0171] When the control device 90 switches the operation of the air conditioner 1B of this embodiment to the first mode, the first utilization heat exchanger 102 and the second utilization heat exchanger 112 both function as condensers to heat (space space) the air in the space to be air-conditioned, as in the second embodiment.

[0172] Furthermore, when the operation of the air conditioner 1B of this embodiment is switched to the third mode by the control device 90, the air conditioner 1B performs dehumidifying operation (dehumidifying reheating operation) in the same manner as in the second embodiment.

[0173] Furthermore, when the operation of the air conditioner 1B of this embodiment is switched to the second mode by the control device 90, the first utilization heat exchanger 102 and the second utilization heat exchanger 112 both function as evaporators, and cool (air-condition) the air in the space to be air-conditioned.

[0174] Furthermore, if the air conditioner 1B continues to operate in the first mode, frost may form on the heat source heat exchanger 16 of the heat source unit 10B, reducing operating efficiency. Therefore, the air conditioner 1B performs a defrosting operation to remove frost after operating in the first mode. The air conditioner 1B performs a defrosting operation in the third mode or the fourth mode. In the third mode, the first use heat exchanger 102 serves as an evaporator, and the second use heat exchanger 112 serves as a condenser. In the fourth mode, both the first use heat exchanger 102 and the second use heat exchanger 112 serve as evaporators. In the defrosting operation in the fourth mode, the operation of the use fan 120 is stopped, thereby suppressing a drop in the indoor temperature. In the defrosting operation in the third mode, defrosting takes longer than in the defrosting operation in the fourth mode, but because the second utilization heat exchanger 112 reheats, the blowing of cold air into the space to be air-conditioned can be suppressed even if the utilization fan 120 continues to operate.

[0175] <Fourth embodiment> FIG. 7 shows an air conditioner 1C according to a fourth embodiment. The configuration of the air conditioner 1C of this embodiment overlaps in part with the configuration of the air conditioner 1 of the first embodiment and the air conditioner 1B of the third embodiment. Therefore, in the description of the fourth embodiment, the same components as those in the first or third embodiment are denoted by the same reference numerals. Also, the following description will mainly focus on the differences between the fourth embodiment and the third embodiment.

[0176] As shown in FIG. 7, the refrigerant circuit 30C of the air conditioner 1C has a first branch connection pipe CP1a that branches off from the first connection pipe CP1 at a branch point K5, and a second branch connection pipe CP2a that branches off from the second connection pipe CP2 at a branch point K6.

[0177] In this embodiment, as shown in Fig. 7, the air conditioner 1C has the utilization unit 50 described in the first embodiment as the utilization unit installed in the bedroom, rather than the utilization unit 100 described in the third embodiment. The utilization unit 50 is connected to a first branch connection pipe CP1a and a second branch connection pipe CP2a, just as the utilization unit 50 in the first embodiment was connected to a first connection pipe CP1 and a second connection pipe CP2.

[0178] The utilization unit 100 is installed, for example, in a bathroom of a house, as shown in FIG. 7. The utilization unit 100 may also be installed, for example, in a kitchen or the like of a house (not shown). The utilization unit 50 is installed, for example, in a bedroom of a house, as shown in FIG. 7. The utilization unit 50 may also be installed, for example, in a living room or the like (not shown).

[0179] With this configuration, in bathrooms and kitchens where humidity tends to be high, it is possible to dehumidify the air-conditioned space while suppressing the temperature of the air-conditioned space.

[0180] However, the present invention is not limited to this configuration, and unlike the example of Figure 7, a usage unit 100 capable of reheat dehumidification operation may be installed in a bedroom or living room where comfort is important, and a usage unit 50 may be installed in a bathroom or kitchen.

[0181] <Modification> (1) Variation A In the second to fourth embodiments, the first utilization heat exchanger 102 is arranged upstream of the second utilization heat exchanger 112 in the air flow path formed by the utilization fan 120, but the arrangement of the first utilization heat exchanger 102 and the second utilization heat exchanger 112 may be reversed.

[0182] (2) Variation B In the second to fourth embodiments, the first utilization heat exchanger 102 and the second utilization heat exchanger 112 may be installed in parallel in the air flow path formed by the utilization fan 120.

[0183] (3) Variation C In the third and fourth embodiments, the four-way switching valve 28 is provided within the heat source units 10B, 10C of the air conditioner 1B, but the four-way switching valve 28 may also be provided in each utilization unit 100, or may be provided in the refrigerant circuits 30B, 30C between the heat source units 10B, 10C and the utilization units 100.

[0184] (4) Variation D In the third and fourth embodiments, the use of a four-way switching valve 28 is described as an example, but the throttle 29 and branch pipe P8 may be omitted, and a three-way valve may be used instead of the four-way switching valve 28.

[0185] (5) Variation E Although the first to fourth embodiments have been described as air conditioners capable of cooling / dehumidifying operation and heating operation, the air conditioner of the present disclosure may also be an air conditioner that performs only cooling and dehumidifying operation (without heating operation). In this case, some of the configurations of the air conditioner described in the first to fourth embodiments that are unnecessary may be omitted.

[0186] <Additional Notes> Although a number of embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims. [Explanation of symbols]

[0187] 1, 1A, 1B, 1C Air conditioner 10, 10A, 10B, 10C heat source unit 12 Compressor 16 Heat source heat exchanger 24 Discharge pressure sensor 26 Intake pressure sensor 30,30A,30B,30C Refrigerant circuit 50, 50A, 50B, 50C, 50D Usage Unit 52 Heat exchanger used (1st heat exchanger) 54 Utilization expansion valve (first expansion device) 56 Fans in use (fans) 64 Humidity Sensor 102 1st use heat exchanger (1st heat exchanger) 104 First utilization expansion valve (first expansion device) 112 Second usage heat exchanger (second heat exchanger) 114 Second utilization expansion valve (second expansion device) CP1 First connecting pipe (connecting pipe) CP1a 1st branch connecting pipe (connecting pipe) CP2 Second connecting pipe (connecting pipe) CP2a 2nd branch connecting pipe (connecting pipe) CP3 Third connecting pipe (connecting pipe) P1 Suction pipe P2 discharge pipe [Prior art documents] [Patent documents]

[0188] [Patent Document 1] International Publication No. 2006 / 003925

Claims

1. An air conditioner installed in a house, A plurality of utilization units (50A to 50D, 100A to 100N) whose operation can be controlled individually; a heat source unit (10, 10A, 10B, 10C) connected to the plurality of utilization units by communication pipes (CP1, CP2, CP3, CP1a, CP1b) and constituting a refrigerant circuit (30, 30A, 30B, 30C) together with the plurality of utilization units; a humidity sensor (64) provided corresponding to each of the utilization units; Equipped with At least one of the utilization units (50D, 100N, 50) is installed in a bedroom, R32 is used as the refrigerant flowing through the refrigerant circuit. Air conditioner (1, 1A, 1B, 1C).

2. An air conditioner installed in a house, A plurality of utilization units (50A to 50D, 100A to 100N) whose operation can be controlled individually; a heat source unit (10, 10A, 10B, 10C) connected to the plurality of utilization units by communication pipes (CP1, CP2, CP3, CP1a, CP1b) and constituting a refrigerant circuit (30, 30A, 30B, 30C) together with the plurality of utilization units; a humidity sensor (64) provided corresponding to each of the utilization units; Equipped with At least one of the utilization units (50A, 50B, 100A, 100) is installed in a bathroom or a kitchen, R32 is used as the refrigerant flowing through the refrigerant circuit. Air conditioner (1, 1A, 1B, 1C).

3. Each of the utilization units has a fan (56, 120) that blows air into the space to be air-conditioned, the fan of the utilization unit (50D, 100N) installed in the bedroom has a plurality of fan operation modes with different rotation speeds, the plurality of fan operation modes includes a fan operation mode for sleep, in which the rotation speed is the smallest among the plurality of fan operation modes; The air conditioner according to claim 1.

4. Each of the utilization units has a first heat exchanger (52, 102); The utilization unit (50A, 50B, 100N) installed in the bathroom or the kitchen performs a dehumidifying operation in which the first heat exchanger functions as an evaporator of the refrigerant, and a drying operation in which condensation water adhering to the first heat exchanger during the dehumidifying operation is removed. The air conditioner according to claim 2.

5. The heat source unit includes a compressor (12), a suction pipe (P1) through which the refrigerant sucked into the compressor flows, a suction pressure sensor (26) provided in the suction pipe, and a heat source heat exchanger (16), Each of the utilization units includes a first heat exchanger (52, 102) and a first expansion device (54, 104) disposed between the heat source heat exchanger and the first heat exchanger in the refrigerant circuit and configured to adjust the amount of the refrigerant passing through the first heat exchanger; When a dehumidifying operation is performed in each of the utilization units, causing the first heat exchanger to function as an evaporator, the first expansion device or the compressor of the utilization unit is controlled so that an evaporation temperature calculated from a detection value of the suction pressure sensor becomes a first target temperature. The air conditioner according to any one of claims 1 to 3.

6. The heat source unit includes a compressor (12), a discharge pipe (P2) through which the refrigerant discharged from the compressor flows, a suction pipe (P1) through which the refrigerant drawn into the compressor flows, and a heat source heat exchanger (16), Each of the utilization units (100A to 100N, 100) includes a first heat exchanger (102), a first expansion device (104) that is disposed between the heat source heat exchanger and the first heat exchanger in the refrigerant circuit (30A, 30B, 30C) and adjusts the amount of refrigerant passing through the first heat exchanger, a second heat exchanger (112), and a second expansion device (114) that is disposed between the heat source heat exchanger and the second heat exchanger in the refrigerant circuit and adjusts the amount of refrigerant passing through the second heat exchanger, When a dehumidification operation is performed in each of the utilization units, the air that has exchanged heat with the first heat exchanger that functions as an evaporator is heated by the second heat exchanger that functions as a condenser. An air conditioner (1A, 1B, 1C) according to any one of claims 1 to 3.

7. The heat source unit has an intake pressure sensor (26) provided in the intake pipe, When the dehumidifying operation is performed in each of the utilization units, the first expansion device or the compressor of the utilization unit is controlled so that an evaporation temperature calculated from a detection value of the suction pressure sensor becomes a first target temperature. The air conditioner according to claim 6.

8. The heat source unit has a discharge pressure sensor (24) provided in the discharge pipe, When the dehumidifying operation is performed in each of the utilization units, the second expansion device or the compressor of the utilization unit is controlled so that a condensing temperature calculated from a detection value of the discharge pressure sensor becomes a second target temperature. The air conditioner according to claim 6.

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