Air conditioner

Abstract

An air conditioner (1) using R32 as a refrigerant includes an outdoor unit (100), a dehumidifying reheating indoor unit (200), a first connection pipe (P1), a second connection pipe (P2), and a third connection pipe (P3). The first connection pipe (P1) connects a refrigerant outlet of an outdoor heat exchanger (12) in a dehumidifying operation with a first expansion valve (V5). The second connection pipe (P2) connects a refrigerant outlet of a first utilization heat exchanger (21) in the dehumidifying operation with a suction pipe (P9). The third connection pipe (P3) connects a discharge pipe (P0) with a refrigerant inlet of a second utilization heat exchanger (22) in the dehumidifying operation. In the dehumidifying operation, refrigerant flowing from the discharge pipe (P0) into the second utilization heat exchanger (22) via the third connection pipe (P3) is condensed in the second utilization heat exchanger (22), and is merged with refrigerant condensed in the outdoor heat exchanger (12) and flowing into the dehumidifying reheating indoor unit (200) via the first connection pipe (P1), and is evaporated in the first utilization heat exchanger (21).

Description

Technical Field

[0001] This invention relates to an air conditioner that uses R32 as a refrigerant. Background Technology

[0002] Previously, air conditioners using R32 as a refrigerant have been proposed. For example, Patent Document 1 (Japanese Patent Application Publication No. 2014-1917) discloses a multi-split air conditioner that uses R32, which has a lower Global Warming Potential (GWP) than R410A, as a refrigerant. This multi-split air conditioner is a vapor compression type air conditioner with multiple units connected to a heat source unit, used for air conditioning multiple spaces within buildings such as office buildings. Summary of the Invention

[0003] The technical problem that the invention aims to solve

[0004] In the multi-split air conditioning units used in the aforementioned office buildings, some units not only have cooling and heating modes for the indoor space, but also a dehumidifying mode. Dehumidification typically involves lowering the evaporation temperature of the heat exchanger below the air dew point to remove moisture from the air.

[0005] However, to improve dehumidification, lowering the evaporation temperature of the heat exchanger will cause the indoor air temperature to drop further, thus reducing indoor comfort during dehumidification operation. Therefore, current practice is to reduce capacity to avoid excessive temperature drops before dehumidification. Multi-split air conditioners used in office buildings have limited dehumidification capacity in dry mode.

[0006] On the other hand, when considering the installation of multi-split air conditioning units in residences, it is anticipated that a small dehumidification capacity will be insufficient. Residences contain spaces such as bathrooms and kitchens where humidity increases due to hot water use, and residents use these humid spaces daily; therefore, air conditioning units with high dehumidification capabilities are required. Furthermore, in spaces like bathrooms, not only dehumidification capacity is required, but also the ability to prevent excessive temperature drops.

[0007] Thus, existing air conditioners using R32 as a refrigerant suffer from technical problems such as insufficient dehumidification capacity or excessive drop in indoor temperature.

[0008] Technical solutions adopted to solve technical problems

[0009] The first-view air conditioner uses R32 as refrigerant and operates in dehumidification mode, comprising a heat source unit, a first utilization unit, a first connecting pipe, a second connecting pipe, and a third connecting pipe. 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. During dehumidification operation, refrigerant flows from the discharge pipe into the heat source heat exchanger. The first utilization unit has a first utilization heat exchanger, a first expansion device, and a second utilization heat exchanger. The first utilization heat exchanger functions as an evaporator during dehumidification operation. The first expansion device expands the refrigerant before it flows into the first utilization heat exchanger during dehumidification operation. The second utilization heat exchanger functions as a condenser during dehumidification operation. The first connecting pipe connects the refrigerant outlet of the heat source heat exchanger during dehumidification operation to the first expansion device. The second connecting pipe connects the refrigerant outlet of the first utilization heat exchanger during dehumidification operation to the suction pipe. The third connecting pipe connects the discharge pipe to the refrigerant inlet of the second utilization heat exchanger during dehumidification operation. In the aforementioned air conditioner, during dehumidification operation, the refrigerant flowing from the discharge pipe into the second utilization heat exchanger via the third connecting pipe condenses in the second utilization heat exchanger and merges with the refrigerant that condenses in the heat source heat exchanger and flows into the first utilization unit via the first connecting pipe, and evaporates in the first utilization heat exchanger.

[0010] In the air conditioner of the first viewpoint, R32 is used as the refrigerant. Therefore, compared with air conditioners using R410A, the dehumidification capacity is improved even with the same refrigerant circulation volume. Furthermore, the air conditioner of the first viewpoint is equipped with three connecting pipes: a first connecting pipe, a second connecting pipe, and a third connecting pipe. During dehumidification operation, the third connecting pipe allows the refrigerant to flow from the discharge pipe of the heat source unit to the second utilization heat exchanger of the first utilization unit. Thus, while the refrigerant evaporates in the first utilization heat exchanger of the first utilization unit to dehumidify the air, the refrigerant condenses in the second utilization heat exchanger to heat the air, thereby increasing the air temperature that has decreased due to dehumidification. Thus, in the air conditioner of the first viewpoint, the adverse conditions of insufficient dehumidification capacity or excessive drop in indoor temperature can be suppressed.

[0011] The second-view air conditioner is the same as the first-view air conditioner, but also includes a second-utilization unit that differs from the first-utilization unit. The first-utilization unit is located in a bathroom or kitchen, which serves as a space for using hot water in the residence.

[0012] In residential homes, there are bathrooms and kitchens. In the bathrooms, hot water is used in showers or baths, resulting in high humidity. In the kitchens, hot water is used for cooking (e.g., separate kitchens, kitchens located in a corner of the living room). These spaces require high dehumidification capabilities. Furthermore, to prevent thermal shock in the bathrooms and suppress temperature drops in the living room, it is also necessary to prevent excessive temperature drops during dehumidification operation. The second-view air conditioner is based on the first-view air conditioner; therefore, it can use R32 as a refrigerant to improve dehumidification capacity and can increase the air temperature that drops due to dehumidification through a second heat exchanger. Thus, the first unit of the second-view air conditioner is suitable for dehumidifying bathrooms or kitchens.

[0013] In addition, the second utilization unit can be structurally the same as or different from the first utilization unit. For example, for spaces such as corridors where the temperature can drop slightly, a second utilization unit without a second utilization heat exchanger can be used.

[0014] The third viewpoint air conditioner is the same as the first viewpoint or the second viewpoint air conditioner, and the first utilization unit also has a second expansion device corresponding to the second utilization heat exchanger.

[0015] Here, in addition to a first expansion device that expands the refrigerant before it flows into the first heat exchanger, a second expansion device corresponding to the second heat exchanger is also provided. Therefore, the amount of refrigerant flowing in the first heat exchanger and the amount of refrigerant flowing in the second heat exchanger can be adjusted.

[0016] The fourth viewpoint's air conditioner is any one of the first to third viewpoints, and also includes a control unit that controls the compressor and the first expansion device during dehumidification operation. The heat source unit also has a pressure sensor that detects the refrigerant pressure. During dehumidification operation, the control unit controls the compressor and the first expansion device based on the pressure sensor's readings to ensure that the evaporation temperature of the refrigerant in the first heat exchanger is lower than the dew point of the air being dehumidified.

[0017] In the fourth viewpoint air conditioner, R32 is used as the refrigerant. Therefore, compared to air conditioners using R410A, the refrigerant circulation volume per unit capacity is reduced. Consequently, even when using the refrigerant pressure detection value measured by the pressure sensor in the heat source unit to infer the evaporation temperature of the refrigerant in the first utilization heat exchanger of the first utilization unit (which is different from the heat source unit), the accuracy of the evaporation temperature inference is higher. This is because even with a slightly longer connecting pipe, the pressure loss of the refrigerant is small as long as the refrigerant circulation volume is low. In view of the above, the control unit of the fourth viewpoint air conditioner controls the compressor and the first expansion device based on the detection value of the pressure sensor. As a result, there is no need to install a temperature sensor for measuring the evaporation temperature in the first utilization heat exchanger of the first utilization unit, which reduces manufacturing costs. Attached Figure Description

[0018] Figure 1 This is the refrigerant circuit diagram of the air conditioner according to the first embodiment.

[0019] Figure 2 This is the control block diagram of an air conditioner.

[0020] Figure 3 This is the refrigerant circuit diagram of the air conditioner according to the second embodiment.

[0021] Figure 4 This is the refrigerant circuit diagram of the air conditioner according to the third embodiment.

[0022] Figure 5 This is the refrigerant circuit diagram of the air conditioner according to the fourth embodiment.

[0023] Figure 6 This is a refrigerant circuit diagram for an air conditioner according to another embodiment. Detailed Implementation

[0024] <First Implementation>

[0025] (1) Structure of the air conditioner

[0026] Reference Figure 1The air conditioner 1 according to the first embodiment will be described. The air conditioner 1 includes an outdoor unit 100 and a dehumidification and reheat indoor unit 200. The outdoor unit 100, which is the heat source unit of the air conditioner 1, includes a compressor 11, an outdoor heat exchanger 12, an outdoor fan 13, an outdoor expansion valve V2, and a storage tank 14. The dehumidification and reheat indoor unit 200, which is the utilization unit of the air conditioner 1, includes: a first utilization heat exchanger 21, which is a first indoor heat exchanger; a second utilization heat exchanger 22, which is a second indoor heat exchanger; and a first expansion valve V5, which is a first expansion device. The first utilization heat exchanger 21 functions as an evaporator in the dehumidification operation described later. The first expansion valve V5 expands the refrigerant flowing into the first utilization heat exchanger 21 in the dehumidification operation. The first expansion valve V5 can be an electric valve or a solenoid valve. The second utilization heat exchanger 22 functions as a condenser in the dehumidification operation.

[0027] Air conditioner 1 is a refrigeration cycle device developed for use in residential buildings. The outdoor unit 100 is installed outdoors, such as on a balcony or in a courtyard. The dehumidification and reheat indoor unit 200 is installed in a bathroom or kitchen, which serves as a space for hot water use within the residence.

[0028] In the air conditioner 1, the compressor 11, outdoor heat exchanger 12, outdoor expansion valve V2, first expansion valve V5, first heat exchanger 21, storage tank 14, and compressor 11 are connected in sequence by piping to form a dehumidification circuit. The air conditioner 1 includes a discharge pipe P0 connected to the refrigerant discharge section of the compressor 11, a first connecting pipe P1, a second connecting pipe P2, and a suction pipe P9 connected to the refrigerant suction section of the compressor 11 as piping.

[0029] The refrigerant discharged from compressor 11 flows through discharge pipe P0. The refrigerant drawn into compressor 11 flows through suction pipe P9. During dehumidification operation, as described later, the refrigerant flows from discharge pipe P0 into outdoor heat exchanger 12, which serves as a heat source heat exchanger.

[0030] The first connecting pipe P1 connects the refrigerant outlet of the outdoor heat exchanger 12, which is in dehumidification operation, to the first expansion valve V5. Specifically, the first connecting pipe P1 connects the discharge pipe P0, the outdoor heat exchanger 12, the outdoor expansion valve V2, the first expansion valve V5, and the first heat exchanger 21 in sequence.

[0031] The second connecting pipe P2 connects the refrigerant outlet of the first heat exchanger 21 during dehumidification operation to the suction pipe P9. Specifically, the second connecting pipe P2 connects the first heat exchanger 21 to the suction pipe P9.

[0032] Here, the discharge pipe P0 is defined as the pipe extending from the discharge side of the compressor 11 to... Figure 1 Point K0. From Figure 1The refrigerant flow direction from point K0 to the first heat exchanger 21 (refer to) Figure 1 The upstream end (marked by the dashed arrow) is defined as part of the first connecting pipe P1. The end from the downstream side of the refrigerant flow direction of the first heat exchanger 21 to... Figure 1 Point K1 is defined as the second connecting pipe P2. From... Figure 1 The point K1 to the suction side of the compressor 11 is defined as the suction pipe P9. The storage tank 14 is located in the middle of the suction pipe P9.

[0033] The dehumidification and reheat indoor unit 200 of the air conditioner 1, in addition to having a first heat exchanger 21 and a first expansion valve V5, also has a second heat exchanger 22, an indoor fan 23 as an air supply device, and a second expansion valve V6 as a second expansion device. The second expansion valve V6 can be an electric valve or a solenoid valve. The first heat exchanger 21 and the second heat exchanger 22 are arranged in the airflow path formed by the indoor fan 23. The first heat exchanger 21 is located upstream of the second heat exchanger 22 in the airflow path formed by the indoor fan 23.

[0034] In air conditioner 1, the middle position of discharge pipe P0, the second heat exchanger 22, the second expansion valve V6, and the middle position of first connecting pipe P1 are connected in sequence to form a reheat circuit. Air conditioner 1 also includes a branch pipe P4 and a third connecting pipe P3 connected in series for piping.

[0035] During the dehumidification operation described later, the third connecting pipe P3 connects the discharge pipe P0 to the refrigerant inlet of the second heat exchanger 22 via the branch pipe P4. Specifically, the third connecting pipe P3 sequentially connects the branch pipe P4, the second heat exchanger 22, the second expansion valve V6, and the middle position of the first connecting pipe P1. The branch pipe P4 branches off from the middle position of the discharge pipe P0. The branch pipe P4... Figure 1 It bifurcates at point K2 and extends to Figure 1 Point K4. The third connecting pipe P3 from Figure 1 Point K4 extends to the area between the outdoor expansion valve V2 and the first expansion valve V5. Figure 1 Point K5.

[0036] Both the dehumidification circuit and the reheat circuit of air conditioner 1 are part of a refrigerant circuit for refrigerant circulation. A single refrigerant of R32 is sealed in the refrigerant circuit of air conditioner 1. Here, a refrigerant containing 99% by weight or more, preferably 99.5% or more of R32, is referred to as "a single refrigerant of R32". Because of the use of this refrigerant, air conditioner 1 can output the same capacity as air conditioners using the widely used R410A, even with a reduction of more than 20% in the refrigerant circulation volume.

[0037] Air conditioner 1 also includes Figure 2 The control unit 50 is shown. The control unit 50 is constructed by connecting an outdoor control unit 50a located in the outdoor unit 100 and an indoor control unit 50b located in the dehumidification and reheat indoor unit 200 via a communication line. The control unit 50 controls the operation of components such as the compressor 11, outdoor fan 13, outdoor expansion valve V2, indoor fan 23, first expansion valve V5, and second expansion valve V6. The control unit 50 is connected to a discharge pressure sensor 51 that detects the pressure of the refrigerant flowing in the discharge pipe P0, a suction pressure sensor 52 that detects the pressure of the refrigerant flowing in the suction pipe P9, and multiple temperature sensors that detect the temperature of the refrigerant. The control unit 50 controls the operation of each component in dehumidification and reheat operation modes, etc., based on the detection values ​​from these sensors.

[0038] (2) Dehumidification operation achieved by dehumidification and reheat operation mode

[0039] During dehumidification operation, the refrigerant flowing from the discharge pipe through the third connecting pipe to the second utilization heat exchanger condenses in the second utilization heat exchanger and merges with the refrigerant that condenses in the heat source heat exchanger and flows into the first utilization unit through the first connecting pipe, and evaporates in the first utilization heat exchanger.

[0040] Next, the dehumidification operation in the dehumidification and reheat operation mode implemented by air conditioner 1 will be explained.

[0041] In dehumidification and reheat operation mode, a portion of the refrigerant compressed and discharged by compressor 11 is transported to outdoor heat exchanger 12, while the remaining portion flows to the second utilization heat exchanger 22 of dehumidification and reheat indoor unit 200. The refrigerant transported to outdoor heat exchanger 12 condenses after heat exchange with outdoor air drawn in by outdoor fan 13, passes through outdoor expansion valve V2, and enters dehumidification and reheat indoor unit 200 via first connecting pipe P1. Conversely, the refrigerant entering the second utilization heat exchanger 22 of dehumidification and reheat indoor unit 200 from discharge pipe P0 via third connecting pipe P3 condenses after heat exchange with indoor air drawn in by indoor fan 23, thereby heating the indoor air. This heating of the indoor air refers to the heating of indoor air cooled and dehumidified in the first utilization heat exchanger 21 (described later), and is therefore referred to hereinafter as "indoor air reheating."

[0042] The refrigerant, after exchanging heat with the indoor air in the second heat exchanger 22, passes through the second expansion valve V6 and reacts with the refrigerant entering the dehumidification and reheat indoor unit 200 from the outdoor unit 100 via the first connecting pipe P1. Figure 1The refrigerant flows at point K5. After flowing, the refrigerant passes through the first expansion valve V5 of the dehumidification and reheat indoor unit 200 and enters the first utilization heat exchanger 21. The refrigerant entering the first utilization heat exchanger 21 exchanges heat with the indoor air drawn in by the indoor fan 23 in the first utilization heat exchanger 21 to dehumidify the indoor air. The dehumidification of the indoor air is carried out by cooling the indoor air to a temperature below the dew point and causing condensation; therefore, more accurately, it refers to the cooling and dehumidification of the indoor air. After exchanging heat with the indoor air in the first utilization heat exchanger 21, the refrigerant flows through the second connecting pipe P2 and is sent to the outdoor unit 100, and then returns to the compressor 11 via the storage tank 14.

[0043] Next, the control of the evaporation temperature of the first heat exchanger 21 during dehumidification operation will be explained. As described above, during dehumidification operation, dehumidification is achieved by cooling the indoor air passing through the first heat exchanger 21 to a temperature below the dew point and causing condensation of moisture in the indoor air on the surface of the first heat exchanger 21. Here, in order to make the indoor humidity close to the set humidity, the control unit 50 determines a target value for the evaporation temperature, which is the temperature of the refrigerant flowing in the first heat exchanger 21. To make the evaporation temperature close to the target value, the inverter frequency of the compressor 11 and the opening degree of the first expansion valve V5 are controlled. Specifically, during dehumidification operation in dehumidification reheat operation mode, the control unit 50 calculates the evaporation temperature of the refrigerant in the first heat exchanger 21 based on the refrigerant pressure detected by the suction pressure sensor 52, and controls the compressor 11 and the first expansion valve V5 in a manner that makes the evaporation temperature close to the target value.

[0044] (3) Characteristics of air conditioners

[0045] (3-1)

[0046] The air conditioner 1 of this embodiment uses R32 as a single refrigerant. Therefore, compared with existing air conditioners using R410A as a refrigerant, it can improve dehumidification capacity even with the same refrigerant circulation rate. Furthermore, the air conditioner 1 is equipped with three connecting pipes: a first connecting pipe P1, a second connecting pipe P2, and a third connecting pipe P3. During dehumidification operation, the refrigerant flows from the discharge pipe P0 of the outdoor unit 100 to the second heat exchanger 22 of the dehumidification and reheat indoor unit 200 through the third connecting pipe P3. Thus, while the refrigerant evaporates in the first heat exchanger 21 of the dehumidification and reheat indoor unit 200 to dehumidify the air, the refrigerant condenses in the second heat exchanger 22 to heat the air, thereby increasing the air temperature that has decreased due to dehumidification.

[0047] Thus, in the air conditioner 1, indoor air can be reheated in the second heat exchanger 22 of the dehumidification and reheating indoor unit 200, thereby suppressing the adverse situation of excessive drop in indoor temperature.

[0048] (3-2)

[0049] The air conditioner 1 of this embodiment is designed for use in a residence. A residence contains a bathroom and a kitchen. In the bathroom, hot water is used in the shower or bath, resulting in high humidity. In the kitchen, hot water is used for cooking. These spaces require high dehumidification capacity. On the other hand, to prevent thermal shock in the bathroom and to suppress temperature drops in the living room, it is also necessary to prevent excessive temperature drops during dehumidification operation.

[0050] The air conditioner 1 of this embodiment uses R32 as a single refrigerant, as described above, which improves dehumidification capacity. Furthermore, the dehumidification and reheat indoor unit 200 of the air conditioner 1 not only has a first heat exchanger 21 for dehumidification during dehumidification operation, but also a second heat exchanger 22 for reheating during dehumidification operation. In the air conditioner 1, high-temperature refrigerant flows from the discharge pipe P0 of the outdoor unit 100 to the second heat exchanger 22 of the dehumidification and reheat indoor unit 200 via a third connecting pipe P3 for reheating. Therefore, it is possible to dehumidify bathrooms or kitchens with high efficiency and to prevent excessive temperature drops in bathrooms or kitchens.

[0051] (3-3)

[0052] In this embodiment, the dehumidification and reheat indoor unit 200 of the air conditioner 1 is equipped with not only a first expansion valve V5 corresponding to the first heat exchanger 21, but also a second expansion valve V6 corresponding to the second heat exchanger 22. Therefore, in the air conditioner 1, the amount of refrigerant flowing through the first heat exchanger 21 and the amount of refrigerant flowing through the second heat exchanger 22 can be adjusted. Thus, in the air conditioner 1, the dehumidification capacity and reheating capacity can be appropriately and precisely controlled according to the set temperature and set humidity.

[0053] (3-4)

[0054] In the air conditioner 1 of this embodiment, R32 is used as the refrigerant as described above. Therefore, compared with air conditioners using R410A, the refrigerant circulation volume per unit capacity is less. Furthermore, in the air conditioner 1 of this embodiment, even when the distance between the outdoor unit 100 and the dehumidification / reheating indoor unit 200 is large, and the first connecting pipe P1, the second connecting pipe P2, and the third connecting pipe P3 are long, the pressure loss of the refrigerant flowing in the refrigerant piping is small due to the small refrigerant circulation volume. Because the refrigerant pressure loss is small, there will not be a large difference between the refrigerant pressure in the suction pipe P9 of the outdoor unit 100 and the refrigerant pressure in the first heat exchanger 21 of the dehumidification / reheating indoor unit 200.

[0055] In view of the above, the control unit 50 of the air conditioner 1 uses the pressure detection value of the suction pressure sensor 52 of the outdoor unit 100 to calculate (infer) the evaporation temperature of the refrigerant in the first heat exchanger 21 of the dehumidification and reheat indoor unit 200 located in the room away from the outdoor unit 100. Even if the evaporation temperature of the refrigerant in the first heat exchanger 21 is calculated in the above manner, a highly accurate inferred value of the evaporation temperature can be obtained. Therefore, in the air conditioner 1, there is no need to install a temperature sensor to directly measure the refrigerant temperature of the first heat exchanger 21, which can reduce manufacturing costs.

[0056] <Second Implementation>

[0057] Figure 3 An air conditioner 1A according to a second embodiment is shown. The structure of the air conditioner 1A of this embodiment has parts that are the same as those of the air conditioner 1 of the first embodiment. Therefore, the same reference numerals are used for the same parts as in the first embodiment, and the parts that are different from those in the first embodiment are described here.

[0058] like Figure 3 As shown, the outdoor unit 100A also has a four-way switching valve V1. The four-way switching valve V1 connects the discharge pipe P0, the first connecting pipe P1, the second connecting pipe P2, and the suction pipe P9, and switches between a first switching state and a second switching state. In the first switching state, the four-way switching valve V1 connects the first connecting pipe P1 to the suction pipe P9 and connects the second connecting pipe P2 to the discharge pipe P0. In the second switching state, the four-way switching valve V1 connects the first connecting pipe P1 to the discharge pipe P0 and connects the second connecting pipe P2 to the suction pipe P9. In the air conditioner 1A, by switching the four-way switching valve V1 of the outdoor unit 100A to the first switching state, it can operate in heating mode; by switching the four-way switching valve V1 of the outdoor unit 100A to the second switching state, it can operate in dehumidification and reheat mode.

[0059] The dehumidification operation of air conditioner 1A in dehumidification and reheat mode is the same as the dehumidification operation performed by air conditioner 1 in the first embodiment, therefore, the description is omitted here. Hereinafter, refer to... Figure 3 The operation of the air conditioner 1A in the heating mode of this embodiment will be described.

[0060] In heating mode, the control unit of air conditioner 1A sets the four-way switching valve V1 of outdoor unit 100A to the first switching state. In this state, a portion of the discharged refrigerant compressed by compressor 11 flows to the first heat exchanger 21 of dehumidification and reheat indoor unit 200, and the remaining portion of the discharged refrigerant flows to the second heat exchanger 22 of dehumidification and reheat indoor unit 200. The refrigerant flowing into the first heat exchanger 21 of dehumidification and reheat indoor unit 200 heats the indoor air by exchanging heat with the indoor air drawn in by indoor fan 23 in the first heat exchanger 21. After exchanging heat with the indoor air in the first heat exchanger 21, the refrigerant passes through the first expansion valve V5. On the other hand, the refrigerant flowing into the second heat exchanger 22 of dehumidification and reheat indoor unit 200 heats the indoor air by exchanging heat with the indoor air drawn in by indoor fan 23 in the second heat exchanger 22. After exchanging heat with the indoor air in the second heat exchanger 22, the refrigerant passes through the second expansion valve V6.

[0061] The refrigerant passing through the first expansion valve V5 and the second expansion valve V6 merge and flow through the first connecting pipe P1 to the outdoor unit 100A. The refrigerant passing through the outdoor expansion valve V2 of the outdoor unit 100A flows into the outdoor heat exchanger 12 and evaporates by exchanging heat with the outdoor air drawn in by the outdoor fan 13. The refrigerant evaporated in the outdoor heat exchanger 12 returns to the compressor 11 via the storage tank 14.

[0062] According to the air conditioner 1A of this embodiment, by setting the four-way switching valve V1 of the outdoor unit 100A to the first switching state, both the first heat exchanger 21 and the second heat exchanger 22 can function as condensers, and can heat the indoor air with high capacity.

[0063] Furthermore, according to the air conditioner 1A of this embodiment, by setting the four-way switching valve V1 of the outdoor unit 100A to the second switching state, it can perform dehumidification operation by the dehumidification and reheat mode in the same way as the first embodiment.

[0064] <Third Implementation Method>

[0065] Figure 4An air conditioner 1B according to a third embodiment is shown. The structure of the air conditioner 1B of this embodiment has parts that are the same as those of the air conditioner 1A of the second embodiment. Therefore, the same reference numerals are used for the same parts as in the second embodiment, and the parts that are different from those in the second embodiment are described here.

[0066] like Figure 4 As shown, the outdoor unit 100B of the air conditioner 1B also includes a branch pipe P5, a branch pipe P6, a throttling element V4, and a four-way switching valve V3. The branch pipe P5 connects to the suction pipe P9... Figure 4 Point K6 is the bifurcation point. The bifurcation pipe P6 originates from the bifurcation pipe P5. Figure 4 The valve branches at point K3. A throttling element V4 is located at the branch pipe P6. A four-way switching valve V3 connects the third connecting pipe P3, branch pipe P4, branch pipe P5, and branch pipe P6, and switches between a first switching state and a second switching state. In the first switching state, the four-way switching valve V3 connects the third connecting pipe P3 to the branch pipe P4, and connects the branch pipe P5 to the branch pipe P6, forming a loop. In the second switching state, the four-way switching valve V3 connects the third connecting pipe P3 to the branch pipe P5, and connects the branch pipe P4 to the branch pipe P6. By introducing the oil accumulated in the four-way switching valve V3 into the loop and separating and recovering it, failure of the four-way switching valve V3 due to oil accumulation can be suppressed. From the viewpoint of suppressing the failure of the four-way switching valve V3, the throttling element V4 is preferably a capillary tube.

[0067] The air conditioner 1B of this embodiment can switch between a first mode, a second mode, a third mode, and a fourth mode via a control unit. In the first mode, both the four-way switching valve V1 and the four-way switching valve V3 switch to the first switching state. In the second mode, both the four-way switching valve V1 and the four-way switching valve V3 switch to the second switching state. In the third mode, both the four-way switching valve V1 and the four-way switching valve V3 switch to the first switching state. In the fourth mode, both the four-way switching valve V1 and the four-way switching valve V3 switch to the second switching state, and the indoor fan 23 stops operating.

[0068] The operation of the air conditioner 1B in this embodiment in the first mode is the same as the operation in the heating mode implemented by the air conditioner 1A in the second embodiment. The operation of the air conditioner 1B in the third mode is the same as the dehumidification operation in the dehumidification-reheat mode implemented by the air conditioner 1A in the second embodiment. The operation of the air conditioner 1B in the second mode (cooling operation) and the operation in the fourth mode (second defrosting operation) are substantially the same; therefore, referring to... Figure 4 The operation in the second mode implemented by the air conditioner 1B of this embodiment will be described.

[0069] In the second mode, the control unit of air conditioner 1B sets the four-way switching valve V1 of outdoor unit 100B to the second switching state, and also sets the four-way switching valve V3 of outdoor unit 100B to the second switching state. As a result, the first connecting pipe P1 is connected to the discharge pipe P0, the second connecting pipe P2 is connected to the suction pipe P9, and the third connecting pipe P3 is connected to the branch pipe P5. In the aforementioned second mode, the refrigerant discharged from compressor 11 flows to outdoor heat exchanger 12. The refrigerant that condenses in outdoor heat exchanger 12 after exchanging heat with outdoor air drawn in by outdoor fan 13 flows through outdoor expansion valve V2 to dehumidification and reheat indoor unit 200. The refrigerant flowing into dehumidification and reheat indoor unit 200... Figure 4 At point K5, the refrigerant is split, with a portion flowing through the first expansion valve V5 into the first heat exchanger 21, and the remaining portion flowing through the second expansion valve V6 into the second heat exchanger 22. In the first heat exchanger 21, the refrigerant exchanges heat with the indoor air drawn in by the indoor fan 23, cooling and evaporating the indoor air. Conversely, in the second heat exchanger 22, the refrigerant also exchanges heat with the indoor air drawn in by the indoor fan 23, cooling and evaporating the indoor air. The refrigerant flowing out of the first heat exchanger 21 and the refrigerant flowing out of the second heat exchanger 22 flow to the outdoor unit 100B respectively, and... Figure 4 The flow converges at point K6 and returns to compressor 11 via storage tank 14.

[0070] According to the air conditioner 1B of this embodiment, if the control unit switches to the first mode, the first heat exchanger 21 and the second heat exchanger 22 both function as condensers, just like in the second embodiment, and can heat the indoor air (heating).

[0071] Furthermore, according to this embodiment, if the air conditioner 1B is switched to the third mode by the control unit, it can perform dehumidification operation by the dehumidification and reheat mode in the same way as in the first embodiment.

[0072] Furthermore, in the air conditioner 1B of this embodiment, if it continues to operate in the first mode, the outdoor heat exchanger 12 of the outdoor unit 100B may sometimes frost over, leading to a decrease in operating efficiency. Therefore, in the air conditioner 1B, after operating in the first mode for a certain period of time, a defrosting operation is performed to remove the frost. The defrosting operation is performed in either the third or fourth mode. In the first defrosting operation implemented by the third mode, the first heat exchanger 21 functions as an evaporator, and the second heat exchanger 22 functions as a condenser. In the second defrosting operation implemented by the fourth mode, both the first heat exchanger 21 and the second heat exchanger 22 function as evaporators. In the second defrosting operation, the operation of the indoor fan 23 is stopped, thereby suppressing the decrease in indoor temperature. Although the defrosting speed is slower in the first defrosting operation than in the second defrosting operation, because the second heat exchanger 22 reheats, cold air will not be blown into the room even if the indoor fan 23 continues to operate.

[0073] <Fourth Implementation>

[0074] Figure 5 An air conditioner 1C according to a fourth embodiment is shown. The structure of the air conditioner 1C of this embodiment has parts that are the same as those of the air conditioner 1B of the third embodiment. Therefore, the same reference numerals are used for the same parts as in the third embodiment, and the parts that are different from those in the third embodiment are described here.

[0075] like Figure 5 As shown, the air conditioner 1C also has a first branch connecting pipe P7 branching from the first connecting pipe P1 and a second branch connecting pipe P8 branching from the second connecting pipe P2. Here, the first branch connecting pipe P7 branches from the first connecting pipe P1... Figure 5 The branch point is K7. Point K7 is located between the first expansion valve V5 and the outdoor expansion valve V2. The second branch connecting pipe P8 connects to the second connecting pipe P2. Figure 5 The point K8 is the bifurcation point.

[0076] In this embodiment, such as Figure 5 As shown, the air conditioner 1C also includes two indoor units 200A and 200B, each equipped with a heat exchanger and an expansion valve. These two indoor units 200A and 200B are connected in parallel with the first branch connection pipe P7 and the second branch connection pipe P8.

[0077] Moreover, as mentioned above, the dehumidification and reheating indoor unit 200 is installed in the bathroom or kitchen of the residence, but the indoor units 200A and 200B are installed in other spaces of the residence, such as the living room, bedroom, children's room, corridor, etc. Figure 5In the design, indoor unit 200A is installed in the living room, and indoor unit 200B is installed in the bedroom. Indoor units 200A and 200B have inferior defrosting capabilities compared to the dehumidification and reheating indoor unit 200. However, for spaces that allow for these defrosting capabilities, it is preferable to install indoor units 200A and 200B, which are cheaper than the dehumidification and reheating indoor unit 200, considering cost.

[0078] <Other Implementation Methods> (1)

[0080] In the first to fourth embodiments, in the airflow path formed by the indoor fan 23, the first heat exchanger 21 is provided upstream of the second heat exchanger 22, but the first heat exchanger 21 and the second heat exchanger 22 can also be interchanged. (2)

[0082] In the first to fourth embodiments, the first heat exchanger 21 and the second heat exchanger 22 may also be connected in parallel with the airflow path formed by the indoor fan. (3)

[0084] In the first embodiment, the outdoor unit 100 has an outdoor expansion valve V2, but the outdoor expansion valve V2 may be omitted. (4)

[0086] In the third embodiment, the four-way switching valve V3 is installed in the outdoor unit 100B of the air conditioner 1B, but the four-way switching valve V3 can also be installed in the dehumidification and reheat indoor unit 200, or between the outdoor unit 100B and the dehumidification and reheat indoor unit 200. (5)

[0088] In the third embodiment, a four-way switching valve V3 is used, but a three-way valve can also be used instead. (6)

[0090] In the third embodiment, the branch pipe P5 connects to the suction pipe P9. Figure 4 The bifurcation occurs at point K6, but it is not limited to this; it can also be as follows: Figure 6 The diagram shows a pipe P5' connected at one end to the four-way switching valve V3 and at the other end to the storage tank 14, instead of the branch pipe P5. Alternatively, the above structure can also be applied to... Figure 5 , Figure 6 In the structure shown. (7)

[0092] In the fourth embodiment, indoor units 200A and 200B are connected in parallel with the first branch connecting pipe P7 and the second branch connecting pipe P8. However, this is not the only embodiment. The first branch connecting pipe P7 and the second branch connecting pipe P8 can also be connected to only one indoor unit, or they can be connected in parallel with three or more indoor units. (8)

[0094] In the fourth embodiment, indoor unit A and indoor unit B have the same structure, but are not limited to this; the structures of indoor unit 200A and indoor unit 200B may also be different. (9)

[0096] In the first to fourth embodiments, a storage tank 14 is provided in the inhalation pipe P9, but it is not limited to this and the storage tank 14 may be omitted. (10)

[0098] In the first to fourth embodiments, the branch pipe in the refrigerant circuit can be, for example, a branch pipe such as a Y-shaped connector, or it can be constructed by opening holes in the pipe and welding. (11)

[0100] As long as they do not contradict each other, the structures of the first to fourth embodiments can be combined or some of the components can be deleted. (12)

[0102] The above describes several embodiments, but it should be understood that various changes in manner and details can be made without departing from the spirit and scope of this disclosure as set forth in the claims.

[0103] Symbol Explanation

[0104] 1. Air conditioner; 11. Compressor; 12. Outdoor heat exchanger (heat source heat exchanger); 21. The first use of a heat exchanger; 22. The second use is a heat exchanger; 50 Control Unit (Control Section); 52. Inhalation pressure sensor (pressure sensor); 100 Outdoor Unit (Heat Source Unit); 200 Dehumidification and Reheat Indoor Unit (First Utilization Unit); 200A Indoor Unit (Second Utilization Unit); P0 discharge pipe; P1 First connecting pipe; P2 Second connecting pipe; P3 Third connecting pipe; P9 Inhalation tube; V5 First expansion valve (first expansion device); V6 Second expansion valve (second expansion device).

[0105] Existing technical documents

[0106] Patent documents

[0107] Patent Document 1: Japanese Patent Application Publication No. 2014-1917

Claims

1. An air conditioner (1) that uses R32 as a refrigerant for dehumidification operation, characterized in that, include: A heat source unit (100) includes a compressor (11), a discharge pipe (P0), a suction pipe (P9), and a heat source heat exchanger (12). The discharge pipe (P0) is for refrigerant discharged from the compressor, the suction pipe (P9) is for refrigerant drawn into the compressor, and the heat source heat exchanger (12) is for refrigerant to flow into the compressor from the discharge pipe during the dehumidification operation. The first utilization unit (200) has a first utilization heat exchanger (21), a first expansion device (V5), and a second utilization heat exchanger (22). The first utilization heat exchanger (21) functions as an evaporator in the dehumidification operation, the first expansion device (V5) expands the refrigerant flowing into the first utilization heat exchanger in the dehumidification operation, and the second utilization heat exchanger (22) functions as a condenser in the dehumidification operation. The first connecting pipe (P1) connects the refrigerant outlet of the heat source heat exchanger during dehumidification operation to the first expansion device. The second connecting pipe (P2) connects the refrigerant outlet of the first heat exchanger during dehumidification operation to the suction pipe. as well as The third connecting pipe (P3) connects the discharge pipe to the refrigerant inlet of the second heat exchanger during the dehumidification operation. During the dehumidification operation, the refrigerant flowing from the discharge pipe into the second utilization heat exchanger via the third connecting pipe condenses in the second utilization heat exchanger and merges with the refrigerant that condenses in the heat source heat exchanger and flows into the first utilization unit via the first connecting pipe, and evaporates in the first utilization heat exchanger.

2. The air conditioner as described in claim 1, characterized in that, It also includes a second utilization unit (200A) that is different from the first utilization unit. The first utilization unit is installed in the bathroom or kitchen, which is a space in the residence where hot water is used.

3. The air conditioner as described in claim 1 or 2, characterized in that, The first utilization unit also has a second expansion device (V6) corresponding to the second utilization heat exchanger.

4. The air conditioner as described in any one of claims 1 to 3, characterized in that, It also includes a control unit (50) that controls the compressor and the first expansion device during dehumidification operation. The heat source unit also has a pressure sensor (52) for detecting the pressure of the refrigerant. The control unit controls the compressor and the first expansion device based on the detection value of the pressure sensor during the dehumidification operation, so that the evaporation temperature of the refrigerant in the first heat exchanger is lower than the dew point of the air to be dehumidified.

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