EP4660558A1

EP4660558A1 - Heat pump apparatus

Info

Publication number: EP4660558A1
Application number: EP23919693.4A
Authority: EP
Inventors: Shota KUMOKAWA
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2023-02-01
Filing date: 2023-02-01
Publication date: 2025-12-10
Also published as: EP4660558A4; JPWO2024161554A1; WO2024161554A1

Abstract

A heat pump apparatus comprising: a plurality of load devices each being configured to adjust a temperature of a temperature adjusting target in a target space of a plurality of target spaces by using refrigerant; a heat source apparatus configured to adjust the temperature of the refrigerant; a relay unit connected to the heat source apparatus and the plurality of load devices via refrigerant pipes for circulating the refrigerant, the relay unit being configured to switch a flow passage of the refrigerant based on an operational state of each of the plurality of load devices; and a controller configured to control the heat source apparatus, the plurality of load devices, and the relay unit, wherein the relay unit includes a plurality of three-way linear expansion valves, and each of the plurality of three-way linear expansion valves is provided at a refrigerant pipe of the refrigerant pipes, connected to each of the plurality of load devices, configured to switch a flow passage of the refrigerant flowing through each of the plurality of load devices, and having an opening degree controlled gradually from a closed state to a fully open state to adjust a flow rate of the refrigerant flowing through each of the plurality of load device.

Description

Technical Field

The present disclosure relates to a heat pump apparatus configured to adjust the temperature of a target with refrigerant.

Background Art

Some known heat pump apparatuses use refrigerant having flammability, such as R32 and R290. Thus, functions to prevent leakage of refrigerant to ambient air have been sought for the heat pump apparatuses. For example, Patent Literature 1 discloses a heat pump apparatus configured to suppress leakage of refrigerant by closing a cut-off valve provided at a load device, such as an indoor unit, when a controller determines that refrigerant leakage is occurring based on a result of detection by a refrigerant pressure detection device and a refrigerant leakage detection device.

Citation List

Patent Literature

[Patent Literature 1] WO2018/0011994

Summary of Invention

Technical Problem

Here, in a heat pump apparatus in which a plurality of load devices are connected to a heat source apparatus, such as an outdoor unit, a cut-off valve, and a refrigerant pressure detection device are mounted in each load device upon installation. In this case, difficult-to-identify refrigerant leakage, such as slow leakage, may be caused by a defect in the installation of the cut-off valve.
A heat pump apparatus of the present disclosure is made in view of the above-stated problems, and an object thereof is to overcome the above problems, and provide a heat pump apparatus that can suppress leakage of refrigerant.

Solution to Problem

A heat pump apparatus according to an embodiment of the present disclosure includes a plurality of load devices each being configured to adjust a temperature of a temperature adjusting target in a target space of a plurality of target spaces by using refrigerant; a heat source apparatus configured to adjust the temperature of the refrigerant; a relay unit connected to the heat source apparatus and the plurality of load devices via refrigerant pipes for circulating the refrigerant, the relay unit being configured to switch a flow passage of the refrigerant based on an operational state of each of the plurality of load devices; and a controller configured to control the heat source apparatus, the plurality of load devices, and the relay unit, wherein the relay unit includes a plurality of three-way linear expansion valves, and each of the plurality of three-way linear expansion valves is provided at a refrigerant pipe of the refrigerant pipes, connected to each of the plurality of load devices, configured to switch a flow passage of the refrigerant flowing through each of the plurality of load devices, and having an opening degree controlled gradually from a closed state to a fully open state to adjust a flow rate of the refrigerant flowing through each of the plurality of load device.

Advantageous Effects of Invention

According to a heat pump apparatus of an embodiment of the present disclosure, the relay unit includes a plurality of three-way linear expansion valves. Each of the three-way linear expansion valves is provided at a refrigerant pipe connected to a corresponding one of the load devices, and is configured to adjust the flow rate of the refrigerant flowing through each of the load devices by the adjustment of the opening degree. Therefore, there is no need to provide a cut-off valve between each load device and a relay unit. This suppresses leakage of refrigerant, such as slow leakage, caused by a defect in the installation of a cut-off valve.

Brief Description of Drawings

[Fig. 1] Fig. 1 is a circuit diagram schematically illustrating the configuration of a heat pump apparatus according to Embodiment 1
[Fig. 2] Fig. 2 is a block diagram illustrating the hardware configuration of the controller in Embodiment 1.
[Fig. 3] Fig. 3 is a flowchart illustrating the process for suppressing refrigerant leakage by the heat pump apparatus of Embodiment 1.
[Fig. 4] Fig. 4 is a circuit diagram that schematically illustrates the configuration of the heat pump apparatus according to Embodiment 2.
[Fig. 5] Fig. 5 is a flowchart illustrating the refrigerant leakage suppression process by the heat pump apparatus according to Embodiment 2.

The following details the embodiments with reference to the drawings. The present disclosure is not limited to the following embodiments and can be variously modified without departing from the spirit of the present disclosure. Additionally, the present disclosure encompasses any combination of configurational elements disclosed in each of the following embodiments that can be combined.

Description of Embodiments

Embodiment 1.

Fig. 1 is a circuit diagram schematically illustrating the configuration of a heat pump apparatus 100 according to Embodiment 1. In Embodiment 1, the heat pump apparatus 100 will be described as an example of an air conditioning apparatus that conditions air in a plurality of target spaces TA. Note, however, that the heat pump apparatus 100 may also be a water heater that adjusts the temperature of water.
The heat pump apparatus 100 includes a plurality of indoor units 1 provided in the plurality of target spaces TA. In Fig. 1, each of the target spaces TA, containing therein a corresponding one indoor unit 1, is schematically represented by a rectangle demarcated by a dotted line. The heat pump apparatus 100 additionally includes an outdoor unit 2, a relay unit 4, and a controller 6. The indoor unit 1 serves as an example of a load device, and the outdoor unit 2 serves as an example of a heat source device. A refrigerant circuit is formed by the outdoor unit 2 being connected with the relay unit 4 via the refrigerant pipe 7, and the relay unit 4 being connected with the plurality of indoor units 1 via the refrigerant pipe 7. The refrigerant circulates in the refrigerant circuit, and the air in each target space TA is cooled or heated by the refrigerant flowing into each indoor unit 1. Furthermore, the air in each target space TA serves as one example of a temperature adjustment target.
The heat pump apparatus 100 according to Embodiment 1 is capable of performing cooling only operation, heating only operation, or combined heating and cooling operation. The term "cooling only operation" refers to an operation in which all the plurality of indoor units 1 perform cooling operation. The term "heating only operation" refers to an operation in which all the plurality of indoor units 1 perform heating operation. The term "combined heating and cooling operation" refers to an operation in which some of the plurality of indoor units 1 perform a cooling operation, while the rest perform a heating operation. In the following, a combined heating and cooling operation where the cooling load is larger than the heating load may be referred to as a "cooling main operation". Similarly, a combined heating and cooling operation where the heating load is larger than the cooling load may be referred to as a "heating main operation". Furthermore, in the following, the cooling only operation and the cooling main operation may each be described as a "first operation". Also, the heating only operation and the heating main operation may each be referred to as a "second operation".
Note that when the heat pump apparatus 100 is a device like a water heater that adjusts the water temperature, the cooling operation refers to the operation where the load device cools the water by conducting heat exchange between the refrigerant and the water, and the heating operation refers to the operation where the load device heats the water by conducting heat exchange between the refrigerant and the water.
The outdoor unit 2 incorporates a compressor 20, a flow switching device 21, a heat source heat exchanger 22, a heat source expansion valve 23, and an accumulator 24 inside its casing that forms the exterior. Furthermore, the outdoor unit 2 also includes the first heat source check valve 27A, the second heat source check valve 27B, the third heat source check valve 27C, and the fourth heat source check valve 27D inside the casing. Below, the casing that constitutes the outer shell of the outdoor unit 2 may also be referred to as a heat source casing. In Fig. 1, the heat source casing is schematically shown as a solid rectangle, including elements of the outdoor unit 2 such as the compressor 20 and flow switching device 21. The accumulator 24, the compressor 20, the flow switching device 21, the heat source heat exchanger 22, and the heat source expansion valve 23 are sequentially connected by a refrigerant pipe 7. The heat source expansion valve 23 and the relay unit 4 are connected by the refrigerant pipe 7, and the flow switching device 21 and the relay unit 4 are connected by the refrigerant pipe 7. Below, the refrigerant pipe 7 connecting the heat source expansion valve 23 and the relay unit 4 may also be referred to as the high-pressure pipe 7A. Furthermore, the refrigerant pipe 7 connecting the flow switching device 21 and the relay unit 4 may also be referred to as a low-pressure pipe 7B. Hence, the heat pump apparatus 100 is configured with the so-called two-pipe system, where the relay unit 4 and the outdoor unit 2 are connected by two refrigerant pipes 7, namely the high-pressure pipe 7A and the low-pressure pipe 7B.
The compressor 20 suctions the low-temperature, low-pressure refrigerant, compresses the suctioned refrigerant, and discharges it in a high-temperature, high-pressure state. The compressor 20 can be a compressor of the scroll type, the rotary type, the reciprocating type, or the screw type, and is an inverter compressor where capacity can be controlled by an inverter. The driving frequency of the compressor 20 is controlled by the controller 6, which will be described later.
The flow switching device 21 is, for example, a four-way valve, and is configured to switch the direction in which the refrigerant flows, that is, the flow passage direction. The heat pump apparatus 100 switches between the first operation and the second operation by the switching process of the flow switching device 21. The flow switching device 21 switches the flow passage direction under the control of the controller 6. The solid part of the flow switching device 21 shown in Fig. 1 represents the refrigerant flow passage during the first operation, and the dashed part represents the refrigerant flow passage during the second operation. In Fig. 1, the flow passage direction of the refrigerant in the outdoor unit 2 during the first operation is indicated by the solid arrow inside the rectangle indicating the heat source casing, and the flow passage direction of the refrigerant in the outdoor unit 2 during the second operation is indicated by the dotted arrow inside the rectangle. In Fig. 1, the direction of the refrigerant flow between the outdoor unit 2 and relay unit 4 during the first operation is indicated by the solid arrow between the outdoor unit 2 and relay unit 4 and during the second operation, it is represented by the dotted arrow between outdoor unit 2 and relay unit 4. The flow switching device 21 may be configured by combining other valves, such as a two-way valve or a three-way valve, not just limited to the examples mentioned above.
The heat source heat exchanger 22 conducts heat exchange between the refrigerant and the object to be heat-exchanged, which is supplied by a fan or pump (not shown). Here, the object to be heat-exchanged refers to the air or water etc. that adjusts the temperature of the refrigerant through heat exchange with the refrigerant. Examples of the object to be heat-exchanged include outdoor air or water. The heat source heat exchanger 22 acts as a condenser that cools and condenses the refrigerant during the cooling main operation and serves as an evaporator that heats and evaporates the refrigerant during the heating main operation.
The heat source expansion valve 23 is capable of reducing the pressure of and expanding the refrigerant by adjusting the flow rate of the refrigerant through adjustment of its opening degree. The heat source expansion valve 23 is, for example, an electronic expansion valve, which is a valve whose opening degree can be controlled by the controller 6. In addition to the aforementioned example, the heat source expansion valve 23 may include other throttling devices such as capillaries.
The accumulator 24 is provided on the low-pressure side, which is the suction side of the compressor 20. The accumulator 24 stores surplus refrigerant caused by operational differences between the first operation and the second operation and the surplus refrigerant due to transient operational changes. Note that the heat pump apparatus 100 may not include an accumulator 24.
The first heat source check valve 27A is provided at the high-pressure pipe 7A. During the first operation, the first heat source check valve 27A allows the refrigerant to flow from the outdoor unit 2 to the relay unit 4. Also, the first heat source check valve 27A blocks the flow of the refrigerant from the relay unit 4 to the outdoor unit 2. The second heat source check valve 27B is provided at the low-pressure pipe 7B. During the first operation, the second heat source check valve 27B allows the refrigerant to flow from the relay unit 4 to the outdoor unit 2. The second heat source check valve 27B blocks the flow of refrigerant from the outdoor unit 2 to the relay unit 4.
The third heat source check valve 27C is provided at the first heat source connection pipe 7C, which connects the downstream side of the first heat source check valve 27A in the high-pressure pipe 7A, and the downstream side of the second heat source check valve 27B in the low-pressure pipe 7B. Note that the first heat source connection pipe 7C is part of the refrigerant pipe 7. During the second operation, the third heat source check valve 27C allows refrigerant to flow from the compressor 20 to the relay unit 4 via the flow switching device 21. The third heat source check valve 27C blocks the flow of refrigerant in the direction opposite to the direction of the refrigerant flow passage from the compressor 20 to the relay unit 4 through the flow switching device 21 during the second operation.
The fourth heat source check valve 27D is provided at the second heat source connection pipe 7D, which connects the upstream side of the first heat source check valve 27A in the high-pressure pipe 7A and that of the second heat source check valve 27B in the low-pressure pipe 7B. Note that the second heat source connection pipe 7D is part of the refrigerant pipe 7. During the second operation, the fourth heat source check valve 27D allows the refrigerant from the relay unit 4 to flow to the heat source expansion valve 23. The fourth heat source check valve 27D blocks the flow of refrigerant in the direction opposite to that from the relay unit 4 to the heat source expansion valve 23 during the second operation.
The indoor unit 1 includes a load expansion valve 10 and a load heat exchanger 11 inside the casing that forms the outer shell. Hereafter, the casing forming the outer shell of the indoor unit 1 may also be referred to as a load casing. In Fig. 1, the load casing, containing both the load expansion valve 10 and load heat exchanger 11 within, is schematically represented by the solid rectangle.
The load expansion valve 10 depressurizes and expands the refrigerant by adjusting its flow rate based on the opening degree. The load expansion valve 10 may be a valve whose opening degree can be controlled by the controller 6, such as an electronic expansion valve. The load expansion valve 10 is not limited to the above example and may also include other throttling devices, such as a capillary.
The load heat exchanger 11 conducts heat exchange between the refrigerant and the temperature adjusting target, which is supplied by a fan or pump (not shown). As a result, the air in the target space TA is either cooled or heated. During the cooling operation, the load heat exchanger 11 serves as an evaporator, heating and vaporizing the refrigerant, and during the heating main operation, it functions as a condenser, cooling and condensing the refrigerant.
In Fig. 1, the flow passage direction of the refrigerant inside the indoor unit 1 during cooling operation is represented by the solid arrow inside the rectangle indicating the load casing. On the other hand, the flow passage direction of the refrigerant inside the indoor unit 1 during heating operation is represented by the dotted arrow inside the rectangle indicating the load casing.
The relay unit 4 switches the flow of the refrigerant according to the operational state of the indoor unit1, distributing low-temperature refrigerant to the indoor unit1 performing cooling operation and distributing high-temperature refrigerant to the indoor unit1 performing heating operation. The relay unit 4 includes a gas-liquid separator 40, a first relay heat exchanger 41, a first relay expansion valve 42, a second relay heat exchanger 43, and a second relay expansion valve 44 inside the relay casing. The relay casing refers to the casing that constitutes the external shell of the relay unit 4. In Fig.1, the relay casing, containing the components of the relay unit 4 such as the gas-liquid separator 40 and the first relay heat exchanger 41, is schematically shown by a rectangle with a double-dotted dash line. Furthermore, the relay unit 4 includes plurality of first relay check valves 45A, a plurality of second relay check valves 45B, and a plurality of three-way linear expansion valves 46 inside the relay casing. Each first relay check valve 45A, each second relay check valve 45B, and each three-way linear expansion valve 46 are provided corresponding to each indoor unit1.
The relay unit 4 includes a relay gas pipe 7E through which gas refrigerant flows, and a relay liquid pipe 7F through which liquid refrigerant flows, all inside the relay casing. Furthermore, the relay unit 4 includes a relay branching pipe 7G and a relay merging pipe 7H within the relay casing. Each of the relay gas pipe 7E, the relay liquid pipe 7F, the relay branching pipe 7G, and the relay merging pipe 7H are part of the refrigerant pipe 7.
The relay liquid pipe 7F is connected to the gas-liquid separator 40 and to each of the plurality of indoor units 1 through a plurality of first distribution pipes 7I. In other words, the relay liquid pipe 7F connects the gas-liquid separator 40 and the plurality of first distribution pipes 7I. Note that each of the first distribution pipes 7I is part of the refrigerant pipe 7. The relay liquid pipe 7F sequentially connects the refrigerant flow passage on the primary side of the first relay heat exchanger 41 mentioned later, the first relay expansion valve 42, and the refrigerant flow passage on the primary side of the second relay heat exchanger 43 mentioned later.
The relay branching pipe 7G is connected to the downstream side of the refrigerant passage on the primary side of the later-mentioned second relay heat exchanger 43 and to the low-pressure pipe 7B. The relay branching pipe 7G sequentially connects the second relay expansion valve 44, the refrigerant passage on the secondary side of the later-mentioned second relay heat exchanger 43, and the first relay heat exchanger 41.
The relay merging pipe 7H is connected to the relay liquid pipe 7F between the first relay expansion valve 42 and the second relay heat exchanger 43, and also connected to each of the plurality of indoor units 1 through each of the plurality of first collecting pipes 7J. In other words, the relay merging pipe 7H connects the relay liquid pipe 7F between the first relay expansion valve 42 and the second relay heat exchanger 43, and the plurality of first collecting pipes 7J. Note that the first collecting pipe 7J is part of the refrigerant pipe 7.
The relay gas pipe 7E connects to the gas-liquid separator 40 and to each of the plurality of three-way linear expansion valves 46 through the plurality of second distribution pipes 7K. In other words, the relay gas pipe 7E connects the gas-liquid separator 40 and the plurality of second distribution pipes 7K. Each second distribution pipe 7K is part of the refrigerant pipe 7.
In Fig. 1, the solid arrows indicate the flow passage direction of the refrigerant that the relay unit 4 provides to the indoor unit 1 performing the cooling operation and the flow passage direction of the refrigerant that it receives from the indoor unit 1 performing the cooling operation. Meanwhile, the dotted arrows indicate the flow passage direction of the refrigerant that the relay unit 4 provides to the indoor unit 1 performing the heating operation and the flow passage direction of the refrigerant that it receives from the indoor unit 1 performing the heating operation.
The gas-liquid separator 40 is connected to the high-pressure pipe 7A, the relay gas pipe 7E, and the relay liquid pipe 7F, and separates the two-phase gas-liquid refrigerant flowing in from the high-pressure pipe 7A into gas refrigerant and liquid refrigerant. The gas refrigerant separated in the gas-liquid separator 40 flows into the three-way linear expansion valve 46 via the relay gas pipe 7E. On the other hand, the liquid refrigerant separated in the gas-liquid separator 40 flows into the first relay heat exchanger 41 via the relay liquid pipe 7F.
The first relay heat exchanger 41 has a primary side refrigerant passage and a secondary side refrigerant passage. The liquid refrigerant flowing out of the gas-liquid separator 40 circulates through the primary side refrigerant passage of the first relay heat exchanger 41. The refrigerant flowing out of the secondary side refrigerant passage of the second relay heat exchanger 43 circulates through the secondary side refrigerant passage of the first relay heat exchanger 41. The refrigerant circulating through the primary side refrigerant passage is subcooled by exchanging heat with the refrigerant circulating through the secondary side refrigerant passage. The secondary side refrigerant passage of the first relay heat exchanger 41 is connected to the low-pressure pipe 7B via the relay distribution pipe 7G. The refrigerant flowing out of the secondary side refrigerant passage of the first relay heat exchanger 41 flows into the low-pressure pipe 7B via the relay distribution pipe 7G
The first relay expansion valve 42 depressurizes and expands the refrigerant by adjusting its flow rate based on the opening degree. The first relay expansion valve 42 can be an electronic expansion valve, for example, that allows the opening degree to be controlled by the controller 6. The first relay expansion valve 42 depressurizes and expands the refrigerant flowing in from the first relay heat exchanger 41. Besides the aforementioned example, the first relay expansion valve 42 may also include other throttling devices, such as a capillary.
The second relay heat exchanger 43 includes a refrigerant passage on the primary side and another on the secondary side. The refrigerant that flows out from the first relay expansion valve 42 circulates through the refrigerant passage on the primary side of the second relay heat exchanger 43. The refrigerant that flows out from the second relay expansion valve 44 circulates through the refrigerant passage on the secondary side of the second relay heat exchanger 43. The refrigerant flowing through the primary side of the second relay heat exchanger 43 is subcooled by undergoing heat exchange with the refrigerant flowing through the secondary side.
The second relay expansion valve 44 depressurizes and expands the refrigerant by adjusting its flow rate based on the opening degree. The second relay expansion valve 44 can be a type of valve that allows the controller 6 to control its opening degree, such as an electronic expansion valve, for example. The second relay expansion valve 44 depressurizes and expands the refrigerant flowing in from the second relay heat exchanger 43. After the pressure reduction in the second relay expansion valve 44, the refrigerant flows into the refrigerant passage on the secondary side of the second relay heat exchanger 43 via the relay distribution pipe 7G. Note that the second relay expansion valve 44 is not limited to the above example and may also include other throttling devices such as capillaries.
Each first relay check valve 45A is provided on corresponding one of the first distribution pipes 7I. Each first relay check valve 45A allows refrigerant from the second relay heat exchanger 43 via the relay liquid pipe 7F to flow to each indoor unit 1. On the other hand, each first relay check valve 45A blocks the flow of refrigerant from each indoor unit 1 to the relay liquid pipe 7F.
Each second relay check valve 45B is provided at the corresponding one of the first collecting pipes 7J. Each second relay check valve 45B allows the refrigerant to flow from each indoor unit 1 to the relay liquid pipe 7F, which is located between the first relay expansion valve 42 and the second relay heat exchanger 43. In other words, in each first collecting pipe 7J, the refrigerant flows from the corresponding one of the indoor units 1 to the relay liquid pipe 7F, which is located between the first relay expansion valve 42 and the second relay heat exchanger 43. Each second relay check valve 45B blocks the flow of the refrigerant from the relay liquid pipe 7F, which is between the first relay expansion valve 42 and the second relay heat exchanger 43, to the corresponding one of the indoor units 1.
Each three-way linear expansion valve 46 is connected to the relay gas pipe 7E via the corresponding one of the second distribution pipes 7K, and to the corresponding one of the indoor units 1 via the first collecting pipe 7L, which is part of the refrigerant pipe 7. Furthermore, each three-way linear expansion valve 46 is connected to the low-pressure pipe 7B via the second collecting pipe 7M, also part of the refrigerant pipe 7. Each three-way linear expansion valve 46 switches the flow passage direction of the refrigerant according to the operational state of the corresponding one of the indoor unit 1s. Specifically, when an indoor unit 1 of the indoor units 1 is performing a cooling operation, the three-way linear expansion valve 46 switches the connection so that the indoor unit 1 and the second collecting pipe 7M are in communication. Additionally, when an indoor unit 1 of the indoor units is performing a heating operation, the three-way linear expansion valve 46 switches the connection so that the second distribution pipe 7K and the indoor unit 1 are in communication.
The three-way linear expansion valve 46 depressurizes and expands the refrigerant by adjusting its flow rate based on the opening degree. The three-way linear expansion valve 46 can be a valve, such as an electronic expansion valve, whose opening degree can be controlled by the controller 6.
Below, a detailed description will be given on the first and second operations performed by the heat pump apparatus 100 according to Embodiment 1. First, the first operation will be described. In the first operation, as indicated by the solid line part in the flow switching device 21 of Fig. 1, the flow switching device 21 switches the refrigerant passage such that the discharge side of the compressor 20 is connected to the heat source heat exchanger 22 and the suction side of the compressor 20 is connected to the low-pressure pipe 7B.
The three-way linear expansion valve 46, which corresponds to the indoor unit 1 performing cooling operation, switches the refrigerant passage to connect the first aggregation pipe 7L and the second collecting pipe 7M. If the first operation is the cooling main operation, the three-way linear expansion valve 46 corresponding to the indoor unit 1 performing heating operation switches the refrigerant passage to connect the first aggregation pipe 7L and the second distribution pipe 7K.
The low-temperature, low-pressure refrigerant is compressed by the compressor 20 and discharged as high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from compressor 20 flows into the heat source heat exchanger 22 through the flow switching device 21. The high-temperature, high-pressure gas refrigerant that has flowed into the heat source heat exchanger 22 exchanges heat with the objects to be heat-exchanged and condenses while radiating heat, becoming a high-pressure two-phase gas-liquid refrigerant or liquid refrigerant and flows out from the heat source heat exchanger 22. During the first operation, in the cooling only operation, the high-temperature, high-pressure gas refrigerant in the heat source heat exchanger 22 becomes high-pressure liquid refrigerant, and during the cooling main operation, the high-temperature, high-pressure gas refrigerant in the heat source heat exchanger 22 becomes high-pressure two-phase gas-liquid refrigerant. The high-pressure two-phase gas-liquid refrigerant or liquid refrigerant that has flowed out from the heat source heat exchanger 22 flows out from the outdoor unit 2 through the first heat source check valve 27A and flows into the relay unit 4.
The high-pressure two-phase gas-liquid refrigerant or liquid refrigerant flowing into the relay unit 4 flows into the gas-liquid separator 40. In the combined heating and cooling operation, the two-phase gas-liquid refrigerant in the gas-liquid separator 40 separates into the high-pressure gas refrigerant and the high-pressure liquid refrigerant. The high-pressure liquid refrigerant in the gas-liquid separator 40 flows into the primary side refrigerant passage of the first relay heat exchanger 41.
The liquid refrigerant that has flowed into the primary side of the first relay heat exchanger 41 is subcooled by the refrigerant flowing through the refrigerant passage on the secondary side of the first relay heat exchanger 41, and it flows out from the refrigerant passage on the primary side of the first relay heat exchanger 41. The liquid refrigerant that has flowed out from the refrigerant passage on the primary side of the first relay heat exchanger 41 flows into the refrigerant passage on the primary side of the second relay heat exchanger 43 through the first relay expansion valve 42. The medium-pressure liquid refrigerant that has flowed into the refrigerant passage on the primary side of the second relay heat exchanger 43 is further subcooled by the refrigerant flowing through the refrigerant passage on the secondary side of the second relay heat exchanger 43 and flows out from the refrigerant passage on the primary side of the second relay heat exchanger 43.
The liquid refrigerant flowing out of the primary side refrigerant passage of the second relay heat exchanger 43 is divided, with a portion flowing into the indoor unit 1 performing cooling operation through the first relay check valve 45A associated with it. The remaining part of the liquid refrigerant flowing out of the primary side refrigerant passage of the second relay heat exchanger 43 is depressurized and expanded by the second relay expansion valve 44 to become low-pressure gas refrigerant, which then flows into the relay distribution pipe 7G. This contributes to the subcooling of the refrigerant flowing through each primary side refrigerant passage of the first relay heat exchanger 41 and the second relay heat exchanger 43.
The liquid refrigerant flowing into the indoor unit 1 performing cooling operation is depressurized and expanded by the load expansion valve 10, becoming low-temperature, low-pressure two-phase gas-liquid refrigerant, or liquid refrigerant, and then flows into the load heat exchanger 11. The low-temperature, low-pressure two-phase gas-liquid refrigerant or liquid refrigerant flowing into the load heat exchanger 11 exchanges heat with the temperature adjusting target, thereby cooling it through heat absorption and evaporation, and becomes low-pressure gas refrigerant that flows out from the load heat exchanger 11. Then, the low-pressure gas refrigerant flowing out of the load heat exchanger 11 flows out of the indoor unit 1 and flows into the relay unit 4. The refrigerant flowing into the relay unit 4 flows into the low-pressure pipe 7B via the three-way linear expansion valve 46 and the second collecting pipe 7M.
When the cooling main operation is performed, the high-pressure gas refrigerant separated in the gas-liquid separator 40 flows out from the relay unit 4, through the second distribution pipe 7K and the three-way linear expansion valve 46, and flows into the indoor unit 1 performing heating operation. The high-temperature, high-pressure gas refrigerant flowing into the indoor unit 1 performing heating operation enters the load heat exchanger 11 and heats the temperature adjusting target by condensing while releasing heat and exchanging heat with the object, becoming high-pressure liquid refrigerant and flowing out of the load heat exchanger 11. The high-pressure liquid refrigerant flowing out of the load heat exchanger 11 is depressurized and expanded by the load expansion valve 10 to become low-pressure refrigerant, and flows into the relay unit 4 from the indoor unit 1.
The refrigerant flowing in from the indoor unit 1, which is performing the heating operation, to the relay unit 4 passes through the second relay check valve 45B, circulates through the relay merging pipe 7H, and flows into the relay liquid pipe 7F between the first relay expansion valve 42 and the second relay heat exchanger 43, merging with the liquid refrigerant from the first relay expansion valve 42. The merged refrigerant then circulates through the refrigerant passage on the primary side of the second relay heat exchanger 43. Part of the refrigerant flowing out of the second relay heat exchanger 43 passes through the first relay check valve 45A corresponding to the indoor unit 1 operating in cooling mode, flows into the indoor unit 1 operating in cooling mode, and contributes to the cooling operation. Meanwhile, the rest of the refrigerant flowing out of the second relay heat exchanger 43 enters the relay branching pipe 7G, sequentially circulates through the second relay expansion valve 44, the second relay heat exchanger 43, and the first relay heat exchanger 41, and flows into the low-pressure pipe 7B.
In the first operation, the refrigerant flowing through the low-pressure pipe 7B flows from the relay unit 4 to the outdoor unit 2 and is suctioned into the compressor 20 after passing through the second heat source check valve 27B, the flow switching device 21, and the accumulator 24. This cycle of refrigerant circulation is repeated.
Next, the second operation will be described. In the second operation, as indicated by the broken line portion in the flow switching device 21 in Fig. 1, the flow switching device 21 is switched by the controller 6 to connect the discharge side of the compressor 20 to the gas-liquid separator 40, and the suction side of the compressor 20 to the heat source heat exchanger 22, thus switching the refrigerant path.
The three-way linear expansion valve 46 associated with the indoor unit 1 performing the heating operation switches the refrigerant passage to connect the first aggregation pipe 7L and the second distribution pipe 7K. If the second operation is the heating main operation, the three-way linear expansion valve 46 associated with the indoor unit 1 performing the cooling operation switches the refrigerant passage to connect the first aggregation pipe 7L and the second collecting pipe 7M.
The low-temperature, low-pressure refrigerant is compressed by the compressor 20 and is discharged as a high-temperature, high-pressure gas refrigerant. The high-temperature, high-pressure gas refrigerant discharged from the compressor 20 is routed through the flow switching device 21 and the fourth heat source check valve 27D, flowing out of the outdoor unit 2, and flows into the relay unit 4. The high-temperature, high-pressure gas refrigerant flowing into the relay unit 4 is directed into the relay gas pipe 7E through the gas-liquid separator 40. The refrigerant circulating in the relay gas pipe 7E flows into the indoor unit 1 performing heating operation through the three-way linear expansion valve 46 associated with the heating-operating indoor unit 1.
The high-temperature, high-pressure gas refrigerant flowing into the indoor unit 1 that is in heating operation enters the load heat exchanger 11. Here, it exchanges heat with the temperature adjusting target, and while dissipating heat and condensing, it becomes high-pressure liquid refrigerant and flows out from the load heat exchanger 11. The high-pressure liquid refrigerant flowing out of the load heat exchanger 11 is depressurized and expanded by the load expansion valve 10 to become intermediate pressure liquid refrigerant, and after flowing out of the indoor unit 1 that is in heating operation, it flows into the relay unit 4.
The intermediate-pressure liquid refrigerant flowing in from the indoor unit 1, which is performing the heating operation, to the relay unit 4, passes through the second relay check valve 45B and flows through the relay merging pipe 7H. The liquid refrigerant flowing through the relay merging pipe 7H enters the refrigerant passage on the primary side of the second relay heat exchanger 43. The liquid refrigerant that has entered the refrigerant passage on the primary side of the second relay heat exchanger 43 is subcooled by the refrigerant flowing in the refrigerant passage on the secondary side of the second relay heat exchanger 43, and then flows out of the refrigerant passage on the primary side of the second relay heat exchanger 43.
When the heating main operation is executed, the liquid refrigerant flowing out of the primary-side refrigerant passage of the second relay heat exchanger 43 is split. Part of the liquid refrigerant passes through the first relay check valve 45A, which is associated with the indoor unit 1 performing the cooling operation, and flows into the indoor unit 1 performing the cooling operation. On the other hand, the rest of the liquid refrigerant flowing out of the primary-side refrigerant passage of the second relay heat exchanger 43 circulates through the relay distribution pipe 7G. After being depressurized by the second relay expansion valve 44, it flows into the secondary-side refrigerant passage of the second relay heat exchanger 43. The refrigerant circulating the secondary-side refrigerant passage of the second relay heat exchanger 43 exchanges heat with the refrigerant circulating the primary-side refrigerant passage of the second relay heat exchanger 43, then flows out of the second relay heat exchanger 43 and flows into the secondary-side refrigerant passage of the first relay heat exchanger 41. The refrigerant circulating the secondary-side refrigerant passage of the first relay heat exchanger 41 exchanges heat with the refrigerant circulating the primary-side refrigerant passage of the first relay heat exchanger 41, then flows out of the first relay heat exchanger 41 and flows into the low-pressure pipe 7B.
The liquid refrigerant flowing into the indoor unit 1, which is performing a cooling operation, is depressurized and expanded by the load expansion valve 10, becoming a low-pressure two-phase gas-liquid refrigerant or liquid refrigerant, and flows in to the load heat exchanger 11. The low-pressure two-phase gas-liquid refrigerant or liquid refrigerant flowing into the load heat exchanger 11 exchanges heat with the temperature adjusting target, absorbing heat and evaporating to cool the temperature adjusting target, and becomes low-pressure gas refrigerant that flows out from the load heat exchanger 11. Then, the low-pressure gas refrigerant flowing out of the load heat exchanger 11 flows into the relay unit 4 from the indoor unit 1. The gas refrigerant flowing into the relay unit 4 passes through the three-way linear expansion valve 46 associated with the indoor unit 1 performing the cooling operation and flows into the low-pressure pipe 7B.
In the case where a heating only operation is performed, the refrigerant flowing out of the primary side refrigerant passage of the second relay heat exchanger 43 flows through the relay distribution pipe 7G and after being depressurized by the second relay expansion valve 44, it flows into the secondary side refrigerant passage of the second relay heat exchanger 43. The refrigerant flowing through the secondary side refrigerant passage of the second relay heat exchanger 43, after conducting heat exchange with the refrigerant flowing through the primary side refrigerant passage of the second relay heat exchanger 43, flows out of the second relay heat exchanger 43 and enters the secondary side refrigerant passage of the first relay heat exchanger 41. The refrigerant flowing through the secondary side refrigerant passage of the first relay heat exchanger 41, after exchanging heat with the refrigerant flowing through the primary side refrigerant passage of the first relay heat exchanger 41, flows out of the first relay heat exchanger 41 and enters the low-pressure pipe 7B.
In the second operation, the refrigerant circulating through the low-pressure pipe 7B flows out of the relay unit 4 and flows into the outdoor unit 2. The refrigerant that has flowed into the outdoor unit 2 enters the heat source heat exchanger 22 through the third heat source check valve 27C and the heat source expansion valve 23. The low-pressure gas refrigerant that has flowed into the heat source heat exchanger 22 exchanges heat with the objects to be heat-exchanged, absorbing heat and evaporating, becoming further gasified, and flowing out of the heat source heat exchanger 22. The low-temperature, low-pressure gas refrigerant that has flowed out of the heat source heat exchanger 22 passes through the flow switching device 21 and accumulator 24 and is sucked into the compressor 20. Subsequently, the above-mentioned cycle repeats.
The heat pump apparatus 100 according to Embodiment 1 is configured with the following elements and features in order to suppress any further leakage of refrigerant in case of a refrigerant leakage from the refrigerant circuit. The heat pump apparatus 100 has multiple refrigerant leakage detection sensors 9. The controller 6 communicates with each of the multiple refrigerant leakage detection sensors 9 via a wired connection. In Fig. 1, the controller 6 and each refrigerant leakage detection sensor 9 are connected by a dashed line representing a signal line, indicating that the controller 6 performs wired communication with each refrigerant leakage detection sensor 9. However, the controller 6 may communicate wirelessly with all or part of the multiple refrigerant leakage detection sensors 9.
Each refrigerant leakage detection sensor 9 is installed in each target space TA and detects refrigerant leakage in the corresponding target space TA. The refrigerant leakage detection sensor 9, for example, detects refrigerant leakage by measuring the concentration of the refrigerant in each target space TA. Note that the process of detecting refrigerant leakage includes the process in which the controller 6 determines the refrigerant leakage based on the refrigerant concentration obtained by each refrigerant leakage detection sensor 9.
The controller 6 controls the compressor 20, the flow switching device 21, the heat source expansion valve 23, the load expansion valve 10, the first relay expansion valve 42, the second relay expansion valve 44, and the three-way linear expansion valve 46 as described above. In Fig. 1, the controller 6 is shown schematically connected to each of the outdoor unit 2 and relay unit 4 by a dashed line representing elements such as signal lines, indicating its ability to communicate with each component of the outdoor unit 2 and the relay unit 4 through wired communication. However, the controller 6 can also conduct wireless communication with all or part of the components of the outdoor unit 2 and relay unit 4. Moreover, in Fig. 1, the controller 6 is shown schematically connected by a dashed line representing elements such as signal lines to each indoor unit 1, indicating that it can communicate with the components of each indoor unit 1 through wired communication. However, the controller 6 may also be configured to communicate wirelessly with the components of the indoor unit 1.
The controller 6 periodically obtains detection results from each refrigerant leakage detection sensor 9. The controller 6 may also obtain detection results from each refrigerant leakage detection sensor 9 when it detects a refrigerant leak. When a refrigerant leak is detected by each refrigerant leakage detection sensor 9, the controller 6 closes the first relay expansion valve 42, the second relay expansion valve 44, and the plurality of three-way linear expansion valves 46. This suppresses the inflow of refrigerant to the plurality of indoor units 1, thereby helping to prevent further leakage of refrigerant in the plurality of target spaces TA.
The controller 6 stops the operation of compressor 20 after closing the first relay expansion valve 42, the second relay expansion valve 44, and a plurality of three-way linear expansion valves 46, or concurrently with the closure of these valves.
The heat pump apparatus 100 according to Embodiment 1 may have one or more notification devices. These notification devices will, based on instructions from the controller 6, notify about refrigerant leakage. The heat pump apparatus 100 may have at least one notification device in each of the plurality of target spaces TA. When a refrigerant leakage detection sensor 9 installed in each target space TA detects a refrigerant leakage, the notification device provided in that target space TA may notify the refrigerant leakage. Alternatively, the heat pump apparatus 100 may have one notification device. When the refrigerant leakage detection sensor 9 in each target space TA detects a refrigerant leakage, the one or more notification devices may notify about the refrigerant leakage in each target space TA.
Referring to Fig. 2, the hardware configuration of the controller 6 in Embodiment 1 will be described. Fig. 2 is a block diagram illustrating the hardware configuration of the controller 6 in Embodiment 1. The controller 6 can be configured by a processor 60, a memory 61, and an input/output interface circuit 62. The processor 60, memory 61, and input/output interface circuit 62 are interconnected via a bus 63. The processor 60 can be, for example, a CPU (Central Processing Unit) or MPU (Micro Processing Unit). The memory 61 can be, for example, a ROM (Read Only Memory) or RAM (Random Access Memory). The function of the controller 6 to obtain detection results from each refrigerant leakage detection sensor 9 can be realized by the input/output interface circuit 62. The function of the controller 6 to control each component of the heat pump apparatus 100, such as the compressor 20 or the plurality of three-way linear expansion valves 46, can be achieved by outputting control signals for controlling each of those components, obtained by the processor 60 reading out and executing various programs stored in the memory 61, to the corresponding components via the input/output interface circuit 62.
The functions implemented by the controller 6, as described above, can also be achieved by dedicated hardware apart from cooperation between software and hardware. For instance, all or part of the controller 6 could possibly be configured with hardware such as a Complex Programmable Logic Device (CPLD) or Field Programmable Gate Array (FPGA).
Referring to Fig. 3, the refrigerant leakage suppressing process by the heat pump apparatus 100 according to Embodiment 1 will be described. Fig. 3 is a flowchart illustrating the process for suppressing refrigerant leakage by the heat pump apparatus 100 of Embodiment 1. In step S1, if at least one of the plurality of refrigerant leakage detection sensors 9 detects a refrigerant leakage (step S1: YES), the process of the heat pump apparatus 100 proceeds to step S2. If the plurality of refrigerant leakage detection sensors 9 does not detect any refrigerant leakage in step S1 (step S1: NO), the heat pump apparatus 100 returns the process to step S1.
In step S2, the controller 6 closes the first relay expansion valve 42, the second relay expansion valve 44, and a plurality of three-way linear expansion valves 46. In step S3, the controller 6 stops the operation of the compressor 20 and notifies one or more notification devices of the refrigerant leakage. Note that the heat pump apparatus 100 may execute the processes of step S2 and step S3 in reverse order, or it may perform them simultaneously.
Hereinafter, the effect of the heat pump apparatus 100 according to Embodiment 1 is described. The heat pump apparatus 100 includes a plurality of load devices, a heat source apparatus, a relay unit 4, and a controller 6. The plurality of load devices adjust the temperature of the temperature adjusting target in a plurality of target spaces TA by using refrigerant. The heat source apparatus adjusts the temperature of the refrigerant. The relay unit 4 is connected with the heat source apparatus and the plurality of load devices by a refrigerant pipe 7 circulating refrigerant, and it switches the refrigerant flow passage according to the operating status of each of the plurality of load devices. The controller 6 controls the heat source apparatus, the plurality of load devices, and the relay unit 4. The relay unit 4 includes a plurality of three-way linear expansion valves 46. Each three-way linear expansion valve 46 is provided on a refrigerant pipe 7 connected to the corresponding load device, and it switches the refrigerant flow passage circulating through the load device, as well as adjusts the flow rate of the refrigerant circulating through the load device by gradually adjusting the opening degree from the close state to the fully open state.
According to the above configuration, the relay unit 4 is equipped with a plurality of three-way linear expansion valves 46, each of which is associated with a specific load device. Each three-way linear expansion valve 46 regulates the flow rate of the refrigerant flowing through the corresponding one of the load devices, eliminating the need to provide a cut-off valve between each load device and the relay unit 4. It should be noted that cut-off valves are often installed during the construction of the heat pump apparatus 100, but refrigerant leakage can occur due to defects in installation. However, refrigerant leakage caused by defective installation of cut-off valves, such as slow leakage, is often difficult to detect during construction. In Embodiment 1, since the three-way linear expansion valve 46, which replaces the cut-off valve, is mounted on the refrigerant pipe 7 built into the relay casing of the relay unit 4, there is no need to install the three-way linear expansion valve 46 at the installation site when installing the relay unit 4. This allows to avoid refrigerant leakage caused by defective installation of the cut-off valve at the installation site.
The heat pump apparatus 100 according to Embodiment 1 features a plurality of refrigerant leakage detection sensors 9 that detect the leakage of refrigerant in multiple target spaces TA. When at least one of the plurality of refrigerant leakage detection sensors 9 detects refrigerant leakage, the controller 6 will close all of the plurality of three-way linear expansion valves 46. As a result, the flow of refrigerant from the heat source apparatus to the plurality of load devices via the relay unit 4 is halted, suppressing the leak of refrigerant and reducing the potential increase in refrigerant concentration within the target spaces TA.
In Embodiment 1, the relay unit 4 includes a relay liquid pipe 7F, a relay distribution pipe 7G, a first relay expansion valve 42, and a second relay expansion valve 44. The relay liquid pipe 7F, part of the refrigerant pipe 7, is used to distribute liquid refrigerant flowing in from the heat source apparatus to all or some of the plurality of load devices. The relay branching pipe 7G, also part of the refrigerant pipe 7, is used to circulate refrigerant to the heat source apparatus. The relay distribution pipe 7G is connected to the relay liquid pipe 7F. The first relay expansion valve 42, provided at the relay liquid pipe 7F, depressurizes and expands the liquid refrigerant flowing in from the heat source apparatus. The second relay expansion valve 44, provided at the relay distribution pipe 7G, depressurizes and expands the refrigerant flowing in from the relay liquid pipe 7F. When any of the multiple refrigerant leakage detection sensors 9 detects a refrigerant leak, the controller 6 closes the first and second relay expansion valves 42 and 44. As a result, the distribution of refrigerant to the plurality of load devices is interrupted, helping to suppress any refrigerant leakage in the target space TA.

Embodiment 2.

The following describes the heat pump apparatus 100 according to Embodiment 2. In Embodiment 2, the same numerical indications as those for the like components in Embodiment 1 are used. Furthermore, unless there are special circumstances, the explanation will be omitted for those parts that have the same structure and function as those in Embodiment 1.
Fig. 4 is a circuit diagram that schematically illustrates the configuration of the heat pump apparatus 100 according to Embodiment 2. As shown in Figure 4, the relay unit 4 in Embodiment 2 is equipped with a relay opening-and-closing valve 47 instead of each first relay check valve 45A in Embodiment 1. The relay opening-and-closing valve 47 is controlled by the controller 6 to be in an open state when the corresponding indoor unit 1 is performing cooling operation. On the other hand, each relay opening-and-closing valve 47 is controlled by the controller 6 to be in a closed state when the corresponding indoor unit 1 is performing heating operation.
In Embodiment 2, when the refrigerant leakage detection sensor 9 in each target space TA detects a refrigerant leakage, the controller 6 closes the three-way linear expansion valve 46 and the relay opening-and-closing valve 47 associated with the indoor unit 1 that conditions the corresponding target space TA. In other words, when the refrigerant leakage detection sensor 9 in any target space TA detects a refrigerant leakage, the controller 6 closes the three-way linear expansion valve 46 and the relay opening-and-closing valve 47 associated with the indoor unit 1 that conditions the corresponding target space TA. Note that in Embodiment 2, when the indoor unit 1 in the target space TA where no refrigerant leakage has been detected by the refrigerant leakage detection sensor 9 is operating, the controller 6 sets the opening and closing states of each three-way linear expansion valve 46 and relay opening-and-closing valve 47 associated with that operating indoor unit 1 according to the operation. This helps to maintain the comfort of the users in the target spaces TA where no refrigerant leakage has occurred.
The controller 6 may close all the three-way linear expansion valves 46 and all the relay shut-off valves 47 if any of the refrigerant leakage detection sensors 9 detect a refrigerant leakage. If the controller 6 is unable to determine which refrigerant leakage detection sensor 9 amongst the plurality has detected the refrigerant, it may close all the three-way linear expansion valves 46 and all the relay shut-off valves 47. Also, the controller 6 may close all the three-way linear expansion valves 46 and all the relay shut-off valves 47 if another sensor detects a refrigerant leakage but it's unable to determine in which target space TA the refrigerant leakage occurred. Either or both the suction pressure sensor 25 and the suction temperature sensor 26, provided at the refrigerant pipe 7 on the suction side of the compressor 20, can be mentioned as such other sensors. The suction pressure sensor 25 is a sensor that detects the pressure of the refrigerant being sucked into the compressor 20, and the suction temperature sensor 26 is a sensor that detects the temperature of the refrigerant being sucked into the compressor 20. If the controller 6 closes all the three-way linear expansion valves 46 and all the relay shut-off valves 47, it stops the operation of the compressor 20. In that case, the controller 6 may also close the first relay expansion valve 42 and the second relay expansion valve 44.
Referring to Fig. 5, an explanation will be given about the refrigerant leakage suppression process by the heat pump apparatus 100 according to Embodiment 2. Fig. 5 is a flowchart illustrating the refrigerant leakage suppression process by the heat pump apparatus 100 according to Embodiment 2. In step S11, if any of a plurality of refrigerant leakage detection sensors 9 detects a refrigerant leakage (step S11: YES), the process of the heat pump apparatus 100 proceeds to step S12. If none of the plurality of refrigerant leakage detection sensors 9 detects refrigerant leakage (step S11: NO), the heat pump apparatus 100 returns to step S11.
In Step S12, the controller 6 causes the three-way linear expansion valve 46 and the relay opening-and-closing valve 47, which are associated with the indoor unit 1 that air conditions the target space TA where leakage of the refrigerant has been detected by the refrigerant leakage detection sensor 9, to close. In Step S13, the controller 6 makes one or more notification devices alert of the refrigerant leakage. Note that the heat pump apparatus 100 may execute the processing of Step S12 and Step S13 in reverse order, or simultaneously.
Below, the advantageous effects of the heat pump apparatus 100 according to Embodiment 2 will be described. In Embodiment 2, the relay liquid pipe 7F is connected to a plurality of load devices via a plurality of first distribution pipes 7I. The relay unit 4 is equipped with a relay switch valve 47 provided in each of the plurality of first distribution pipes 7I. The controller 6 closes all of the plurality of relay switch valves 47 when at least one of the plurality of refrigerant leakage detection sensors 9 detects a refrigerant leakage. As a result, the flow of refrigerant to a plurality of load devices is cut off, thereby suppressing refrigerant leakage in the target space TA.
The heat pump apparatus 100 according to Embodiment 2 has a plurality of refrigerant leakage detection sensors 9 for detecting refrigerant leakage in a plurality of target spaces TA. If any of the refrigerant leakage detection sensors 9 detects refrigerant leakage, the controller 6 moves to close some of the three-way linear expansion valves 46. In addition, the controller 6 controls the rest of the three-way linear expansion valves 46 based on the operational state of the corresponding load devices among the plurality of load devices. The part of the three-way linear expansion valves 46 corresponds to certain load devices provided to adjust the temperature of the temperature adjusting target in the target spaces TA, where the refrigerant leakage was detected, among the plurality of target spaces TA. As a result, the heat pump apparatus 100 can continue to operate in target spaces TA where there is no refrigerant leakage, and further suppress refrigerant leakage in target spaces TA where refrigerant leakage has been detected.
The relay unit 4, according to Embodiment 1 of the present disclosure, includes a relay liquid pipe 7F. The relay liquid pipe 7F, which is part of the refrigerant pipe 7, is used to circulate the liquid part of the refrigerant that flows in from the heat source apparatus, to all or part of the plurality of load devices. The relay liquid pipe 7F is connected to a plurality of load devices via a plurality of first distribution pipes 7I. Each of the plurality of first distribution pipes 71 has a relay opening-and-closing valve 47 associated with the corresponding one of the plurality of load devices. When one of the plurality of refrigerant leakage detection sensors 9 detects a refrigerant leak in part of the plurality of target spaces TA, the controller 6 closes some of the relay opening-and-closing valves 47, which are associated with the load devices that adjust the temperature of the temperature adjusting target in at least one of the target spaces TA among the plurality of load devices, and controls the remaining relay opening-and-closing valves 47 according to the operational state of the remaining load devices associated with the remaining relay opening-and-closing valves 47. As a result, the heat pump apparatus 100 can continue to operate in the target spaces TA where the refrigerant is not leaking and can mitigate further refrigerant leaks in the target spaces TA where the refrigerant is leaking.

Reference Signs List

1: indoor unit, 2: outdoor unit, 4: relay unit, 6: controller, 7: refrigerant pipe, 7A: high-pressure pipe, 7B: low-pressure pipe, 7C: first heat source connection pipe, 7D: second heat source connection pipe, 7E: relay gas pipe, 7F: relay liquid pipe, 7G: relay distribution pipe, 7H: relay merging pipe, 7I: first distribution pipe, 7J: first collecting pipe, 7K: second distribution pipe, 7L: first aggregation pipe, 7M: second collecting pipe, 9: refrigerant leakage detection sensor, 10: load expansion valve, 11: load heat exchanger, 20: compressor, 21: flow switching device, 22: heat source heat exchanger, 23: heat source expansion valve, 24: accumulator, 25: suction pressure sensor, 26: suction temperature sensor, 27A: first heat source check valve, 27B: second heat source check valve, 27C: third heat source check valve, 27D: fourth heat source check valve, 40: gas-liquid separator, 41: first relay heat exchanger, 42: first relay expansion valve, 43: second relay heat exchanger, 44: second relay expansion valve, 45A: first relay check valve, 45B: second relay check valve, 46: three-way linear expansion valve, 47: relay opening-and-closing valve, 60: processor, 61: memory, 62: input/output interface circuit, 63: bus, 100: heat pump apparatus, TA: target space

Claims

A heat pump apparatus comprising:
a plurality of load devices each being configured to adjust a temperature of a temperature adjusting target in a target space of a plurality of target spaces by using refrigerant;

a heat source apparatus configured to adjust the temperature of the refrigerant;

a relay unit connected to the heat source apparatus and the plurality of load devices via refrigerant pipes for circulating the refrigerant, the relay unit being configured to switch a flow passage of the refrigerant based on an operational state of each of the plurality of load devices; and

a controller configured to control the heat source apparatus, the plurality of load devices, and the relay unit,

wherein

the relay unit includes a plurality of three-way linear expansion valves, and

each of the plurality of three-way linear expansion valves is provided at a refrigerant pipe of the refrigerant pipes, connected to corresponding one of the plurality of load devices, configured to switch a flow passage of the refrigerant flowing through the corresponding one of the plurality of load devices, and having an opening degree controlled gradually from a closed state to a fully open state to adjust a flow rate of the refrigerant flowing through each of the plurality of load device.
The heat pump apparatus of claim 1, further comprising a plurality of refrigerant leakage detection sensors configured to detect leakage of refrigerant in the plurality of target spaces, wherein
the controller is configured to, when at least any one of the plurality of refrigerant leakage detection sensors detect leakage of refrigerant, close all of the plurality of three-way linear expansion valves.
The heat pump apparatus of claim 2, wherein
the relay unit includes

a relay liquid pipe being part of the refrigerant pipe, and being configured to distribute a part or all of a liquid part of the refrigerant of the refrigerant flowing in from the heat source apparatus to the plurality of load devices,

a relay distribution pipe being part of the refrigerant pipes, the relay distribution pipe being connected to the relay liquid pipe, and configured to distribute the refrigerant to the heat source apparatus,

a first relay expansion valve provided at the relay liquid pipe, and configured to depressurize and expand the liquid part of the refrigerant flowing in from the heat source apparatus, and

a second relay expansion valve provided at the relay distribution pipe and configured to depressurize and expand the refrigerant flowing in from the relay liquid pipe,

wherein the controller is configured to close the first relay expansion valve and the second relay expansion valve when at least one of the plurality of refrigerant leakage detection sensors detects leakage of refrigerant.
The heat pump apparatus of claim 2, wherein
the relay unit includes

a relay liquid pipe being part of the refrigerant pipe and configured to distribute liquid part of the refrigerant of the refrigerant flowing in from the heat source apparatus to all or part of the plurality of load devices, and

the relay liquid pipe is connected via the plurality of load devices and a plurality of first distribution pipes, and

a plurality of relay opening-and-closing valves are provided at the plurality of first distribution pipes, and

the controller is configured to, when at least one of the plurality of refrigerant leakage detection sensors detects leakage of refrigerant, close all of the plurality of relay opening-and-closing valves.
The heat pump apparatus of claim 1, further comprising
a plurality of refrigerant leakage detection sensors configured to detect leakage of refrigerant in the plurality of target spaces,

wherein the controller is configured to, when at least one of the refrigerant leakage detection sensors of the plurality of refrigerant leakage detection sensor detect leakage of refrigerant, close at least one of three-way linear expansion valves of the plurality of three-way linear expansion valves, and control rest of three-way linear expansion valve based on an operational state of the load device, associated with the three-way valve, of the plurality of load devices,

the at least one of three-way linear expansion valves is associated with at least one of the plurality of load devices configured to adjust a temperature of the temperature adjusting target in a target space in which the leakage of refrigerant is detected of the plurality of target spaces.
The heat pump apparatus of claim 5, wherein
the relay unit further comprises a relay liquid pipe being part of the refrigerant pipe and configured to distribute a liquid part of the refrigerant flowing in from the heat source apparatus to all or at least one of the plurality of load devices,

the relay liquid pipe is connected to the plurality of load devices via a plurality of first distribution pipes,

a relay opening-and-closing valve is provided at each of the plurality of first distribution pipes, the relay opening-and-closing valve being associated with a corresponding one of the plurality of load devices, and

the controller is configured to,

when at least one of refrigerant leakage detection sensors of the plurality of refrigerant leakage detection sensors detects leakage of refrigerant in a target space being part of the plurality of target spaces, close a relay opening-and-closing valve being part of the plurality of relay opening-and-closing valves, the relay opening-and-closing valve being associated with a load device, adjusting the temperature of the temperature adjusting target in the part of the target space, of the plurality of load devices, and

control rest of the relay opening-and-closing valves of the plurality of relay opening-and-closing valve based on an operational state of rest of the plurality of load devices associated with the relay opening-and-closing valve.