EP4603762A1

EP4603762A1 - Refrigeration cycle apparatus

Info

Publication number: EP4603762A1
Application number: EP25151824.7A
Authority: EP
Inventors: Junji Hayashi; Takayuki Iseki; Kazuhiko Machida
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2024-02-14
Filing date: 2025-01-14
Publication date: 2025-08-20
Also published as: JP2025124159A

Abstract

The present disclosure provides a refrigeration cycle apparatus that can restrain the internal temperature of a compressor from excessively rising at the start of the compressor. The refrigeration cycle apparatus in the present disclosure includes: a first bypass refrigerant circuit providing communication between a main refrigerant circuit on a downstream side of a compressor and the main refrigerant circuit on an upstream side of the compressor; a first bypass valve provided in the first bypass refrigerant circuit, the first bypass valve being configured to open and close the first bypass refrigerant circuit; a water temperature sensor configured to detect a temperature of water flowing into a use side heat exchanger from a water pipe; and a controller configured to recognize an operating state of the compressor based on the temperature detected by the water temperature sensor at start of the compressor and bring the first bypass refrigerant circuit into an open state using the first bypass valve when recognizing that the compressor is in a predetermined insufficient refrigerant discharge state.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a refrigeration cycle apparatus.

Description of the Related Art

Japanese Patent Laid-Open No. 2000-346449 discloses a configuration of a water heater that heats water in a hot water storage tank through a refrigeration cycle, in which an overshoot in the discharge pressure of a compressor is restrained by setting a dead time period in which the opening degree of a decompression device is kept constant at the start of the compressor.
The present disclosure provides a refrigeration cycle apparatus that can restrain the internal temperature of a compressor from excessively rising at the start of the compressor.

SUMMARY OF THE INVENTION

A refrigeration cycle apparatus in the present disclosure includes: a main refrigerant circuit through which a refrigerant circulates, the main refrigerant circuit including a compressor, a use side heat exchanger, an expansion valve, and a heat source side heat exchanger connected in order, the use side heat exchanger being connected to a water pipe and being configured to perform heat exchange between water flowing through the water pipe and the refrigerant flowing through the main refrigerant circuit; a first bypass refrigerant circuit providing communication between the main refrigerant circuit on a downstream side of the compressor and the main refrigerant circuit on an upstream side of the compressor; a first bypass valve provided in the first bypass refrigerant circuit, the first bypass valve being configured to open and close the first bypass refrigerant circuit; a water temperature sensor configured to detect a temperature of the water flowing into the use side heat exchanger from the water pipe; and a controller configured to recognize an operating state of the compressor based on the temperature detected by the water temperature sensor at start of the compressor and bring the first bypass refrigerant circuit into an open state using the first bypass valve when recognizing that the compressor is in a predetermined insufficient refrigerant discharge state.

Advantageous Effect of Invention

The refrigeration cycle apparatus of the present disclosure can restrain the internal temperature of the compressor from excessively rising at the start of the compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram of a refrigeration cycle apparatus in an embodiment;
FIG. 2 is a control block diagram of the refrigeration cycle apparatus in the embodiment;
FIG. 3 is a flowchart of a handling process at the start of a compressor in the embodiment;
FIG. 4 is a configuration diagram of a refrigeration cycle apparatus in a first modification;
FIG. 5 is a configuration diagram of a refrigeration cycle apparatus in a second modification; and
FIG. 6 is a configuration diagram of a refrigeration cycle apparatus in a third modification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(Knowledge and the like Underlying Present Disclosure)

At the time when the inventors conceived of the present disclosure, there was a technique of setting a dead time period in which the opening degree of a decompression device (expansion valve) is kept constant at the start of a compressor in a heat pump water heater using a refrigeration cycle apparatus. The technique improves the efficiency of operation at the start of the compressor by waiting for a delay in the rise in temperature relative to pressure in a transient state at the start of the compressor and achieves the heat pump water heater having high durability.
However, in the case of the above technique, since the opening degree of the expansion valve is limited at the start of the compressor, the amount of refrigerant suctioned into the compressor becomes insufficient, which disadvantageously causes the amount of refrigerant circulating to become insufficient. In addition, depending on the temperature of water flowing into a use side heat exchanger that heats the water, the pressure of the refrigerant discharged from the compressor becomes less than the pressure of the refrigerant in the use side heat exchanger, which causes the refrigerant to build up. This disadvantageously causes the internal temperature of the compressor to excessively rise, resulting in a failure of the compressor. The inventors have found a problem of how to avoid the occurrence of these disadvantages, and have come to constitute the subject matter of the present disclosure to solve the problem.
Thus, the present disclosure provides a refrigeration cycle apparatus that can restrain the internal temperature of a compressor from excessively rising at the start of the compressor.
Hereinbelow, embodiments will be described in detail with reference to the drawings. Note that more details than necessary may be omitted. For example, detailed description of already well-known matters or repetitive description for substantially identical configurations may be omitted. This is to avoid making the following description unnecessarily redundant and facilitate the understanding of those skilled in the art.
Note that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter described in the claims.

(Embodiment)

Hereinbelow, an embodiment will be described with reference to FIGS. 1 to 3.

[1. Configuration]

FIG. 1 is a configuration diagram of a refrigeration cycle apparatus 1 according to the present embodiment. The refrigeration cycle apparatus 1 is a vapor compression refrigeration cycle apparatus, and includes a main refrigerant circuit 10 and bypass refrigerant circuits 20, 30, and a controller 50. The refrigeration cycle apparatus 1 is installed outdoors and connected to a heating terminal (not shown) by a use side heating medium circuit 100 to constitute a hot water heating system.
The main refrigerant circuit 10 includes a compressor 11 that compresses a refrigerant, a use side heat exchanger 12 that functions as a radiator, an economizer 13, a main expansion valve 14, and a heat source side heat exchanger 15 that functions as an evaporator connected in order through a refrigerant pipe 16. The main expansion valve 14 is an opening adjustable valve whose opening degree is changeable by, for example, a stepping motor. In the present embodiment, the refrigerant pipe 16 is provided with a four-way valve 17 between the compressor 11 and the use side heat exchanger 12. The four-way valve 17 switches the direction in which the refrigerant discharged from the compressor 11 flows.
That is, the four-way valve 17 performs switching between a first direction state in which the refrigerant discharged from the compressor 11 flows in a direction indicated by chain-line arrows in FIG. 1 through the compressor 11, the four-way valve 17, the use side heat exchanger 12, the economizer 13, the main expansion valve 14, the heat source side heat exchanger 15, the four-way valve 17, and the compressor 11 in this order and a second direction state in which the refrigerant flows in a direction opposite to the direction in the first direction state through the compressor 11, the four-way valve 17, the heat source side heat exchanger 15, the main expansion valve 14, the economizer 13, the use side heat exchanger 12, the four-way valve 17, and the compressor 11 in this order. In the second direction state, the heat source side heat exchanger 15 functions as a radiator, and the use side heat exchanger 12 functions as an evaporator. In the present embodiment, a case in which the refrigeration cycle apparatus 1 is operated in the first direction state in which the use side heat exchanger 12 functions as a radiator will be described.
The bypass refrigerant circuit 20 branches off from the main refrigerant circuit 10 between the use side heat exchanger 12 and the main expansion valve 14 and communicates with an injection port 11a provided in a compression chamber of the compressor 11. The compressor 11 is a scroll compressor. A bypass expansion valve 21 and the economizer 13 are connected to the bypass refrigerant circuit 20 in this order from the upstream side. The bypass expansion valve 21 is an on-off valve that is switched between an open state and a closed state, or an opening changeable valve whose opening degree is adjustable.
Part of the high-pressure refrigerant passing through the use side heat exchanger 12 flows into the bypass refrigerant circuit 20 and is decompressed by the bypass expansion valve 21 to become an intermediate-pressure refrigerant. The intermediate-pressure refrigerant exchanges heat with the high-pressure refrigerant flowing through the main refrigerant circuit 10 in the economizer 13 and is then injected into the compressor 11.
The refrigerant injected into the compressor 11 merges with the refrigerant in the process of being compressed in the compression chamber of the compressor 11. The compressor 11 merges the injected refrigerant with the refrigerant in the process of being compressed and performs recompression.
The bypass refrigerant circuit 30 provides communication between the main refrigerant circuit 10 on the discharge side of the compressor 11 and the main refrigerant circuit 10 on the intake side of the compressor 11. The bypass refrigerant circuit 30 is provided with a bypass two-way valve 31. The bypass two-way valve 31 is an on-off valve that is switched between an open state and a closed state. The bypass refrigerant circuit 20 and the bypass refrigerant circuit 30 correspond to the first bypass refrigerant circuit of the present disclosure that provides communication between the main refrigerant circuit 10 on the upstream side of the compressor 11 and the main refrigerant circuit 10 on the downstream side of the compressor 11. In addition, the bypass expansion valve 21 and the bypass two-way valve 31 correspond to the first bypass valve of the present disclosure that opens and closes the first bypass refrigerant circuit.
The use side heating medium circuit 100 includes the use side heat exchanger 12, a feed pump 102, and the heating terminal (not shown) that are connected through a heating medium pipe 101. Water or an antifreeze solution can be used as a heating medium passed through the use side heating medium circuit 100. In the present embodiment, water is used as the heating medium, and the heating medium pipe 101 corresponds to the water pipe of the present disclosure. The use side heat exchanger 12 performs heat exchange between the water flowing through the heating medium pipe 101 and the refrigerant discharged from the compressor 11 to the main refrigerant circuit 10 to heat the water flowing through the heating medium pipe 101. The water heated in the use side heat exchanger 12 is used for heating by heat dissipation from the heating terminal, and the water that has become a low temperature due to the heat dissipation from the heating terminal is heated again in the use side heat exchanger 12.
In a case in which the refrigeration cycle apparatus 1 constitutes a hot water storage type hot water supply system, the heating medium pipe 101 is connected to an upper part and a lower part of a hot water storage tank, water heated in the use side heat exchanger 12 is fed from the upper part of the hot water storage tank into the hot water storage tank through the heating medium pipe 101 and stored in the hot water storage tank, and low-temperature water is fed from the lower part of the hot water storage tank into the heating medium pipe 101 and heated in the use side heat exchanger 12.
The refrigerant pipe 16 is provided with, on the discharge side of the compressor 11, a discharge pressure sensor 40 that detects the pressure of the refrigerant discharged from the compressor 11. The heating medium pipe 101 is provided with, on the inlet side of the use side heat exchanger 12, a water temperature sensor 42 that detects the temperature of the water flowing into the use side heat exchanger 12. An outside air temperature sensor 41 that detects the outside air temperature is provided near the heat source side heat exchanger 15.
FIG. 2 is a control block diagram of the refrigeration cycle apparatus 1. Referring to FIG. 2, the controller 50 is connected to the discharge pressure sensor 40, the outside air temperature sensor 41, and the water temperature sensor 42, and detection signals of these sensors are input to the controller 50. The controller 50 is also connected to the compressor 11, the main expansion valve 14, the four-way valve 17, a heat source fan 18, the bypass expansion valve 21, the bypass two-way valve 31, and the feed pump 102, and the actuation of these objects to be controlled is controlled by control signals output from the controller 50.
A remote control 60 for performing operations such as start and stop of the operation of the refrigeration cycle apparatus 1 is connected to the controller 50. The remote control 60 includes a switch, and a display unit. An operation signal of the switch is input to the controller 50, and the actuation state of the refrigeration cycle apparatus 1 is displayed on the display unit of the remote control 60 in accordance with a display signal output from the controller 50.
The controller 50 includes a processor 51, and a memory 52. A program 53 for controlling the refrigeration cycle apparatus 1 and control data 54 for determining control conditions for the refrigeration cycle apparatus 1 are stored in the memory 52. The processor 51 reads and executes the program 53, thereby controlling the actuation of the refrigeration cycle apparatus 1.

[2. Handling Process at Start of Compressor]

A process executed by the controller 50 at the start of the compressor 11 will be described in accordance with a flowchart shown in FIG. 3. The controller 50, for example, executes the process of the flowchart shown in FIG. 3 when starting the circulation of the water in the use side heating medium circuit 100 using the feed pump 102 and the circulation of the refrigerant in the main refrigerant circuit 10 using the compressor 11 in response to an operation to start heating operation using the remote control 60.
In step S1 of FIG. 3, the controller 50 advances the process to step S2 when the compressor 11 starts. In step S2, the controller 50 recognizes the temperature of the water flowing into the use side heat exchanger 12 based on a detection signal of the water temperature sensor 42. In the following step S3, the controller 50 recognizes the outside air temperature based on a detection signal of the outside air temperature sensor 41. In the next step S4, the controller 50 determines whether the temperature of the water flowing into the use side heat exchanger 12 is higher than the outside air temperature by Tth (corresponding to the first predetermined temperature of the present disclosure) or more. The state in which the temperature of the water flowing into the use side heat exchanger 12 is higher than the outside air temperature by Tth or more corresponds to the insufficient refrigerant discharge state of the present disclosure.
Then, the controller 50 advances the process to step S5 when the temperature of the water is higher than the outside air temperature by Tth or more (the water temperature - the outside air temperature ≥ Tth), and advances the process to step S20 when the temperature of the water is lower than the outside air temperature + Tth. In step S20, the controller 50 executes normal heating operation control to control the rotational speed of the compressor 11, the opening degree of the main expansion valve 14, the opening and closing of the bypass expansion valve 21, and the like so that the temperature of the water flowing out of the use side heat exchanger 12 becomes a predetermined target temperature.
Steps S5 to S9 are processes for restraining the internal temperature of the compressor 11 from excessively rising. The controller 50 opens the bypass expansion valve 21 in step S5 and opens the bypass two-way valve 31 in step S6. Accordingly, the amount of refrigerant suctioned into the compressor 11 increases, and the amount of refrigerant discharged from the compressor 11 increases. As a result, the amount of refrigerant remaining in the compressor 11 decreases, and the excessive rise in the internal temperature of the compressor 11 is restrained.
In the following step S7, the controller 50 recognizes the temperature of the water flowing into the use side heat exchanger 12 based on the temperature detected by the water temperature sensor 42. In step S8, the controller 50 recognizes the outside air temperature based on a detection signal of the outside air temperature sensor 41. In the next step S9, the controller 50 determines whether the state in which the temperature of the water is higher than the outside air temperature by Tth or more has been continued.
Then, the controller 50 advances the process to step S7 when the temperature of the water is higher than the outside air temperature by Tth or more. In this case, the bypass expansion valve 21 and the bypass two-way valve 31 are maintained open. On the other hand, when the temperature of the water is lower than the outside air temperature + Tth, the controller 50 advances the process to step S10. In step S10, the controller 50 closes the bypass two-way valve 31. In the following step S11, the controller 50 shifts the process to the normal heating operation control.
It is assumed that the state in which the bypass expansion valve 21 and the bypass two-way valve 31 are maintained open through the processes in steps S5 and S6 gradually increases the flow rate of the refrigerant in the main refrigerant circuit 10, which prevents the internal temperature of the compressor 11 from excessively rising. Thus, when a predetermined time elapses from a point in time when the compressor 11 starts in step S1, even if the condition in step S9 is satisfied, the process may be forcibly advanced to step S10 and shifted to the normal heating operation control in step S11.

[3. Effects and the like]

As above, in the present embodiment, the refrigeration cycle apparatus 1 includes the main refrigerant circuit 10 through which the refrigerant circulates, the main refrigerant circuit 10 including the compressor 11, the use side heat exchanger 12, the economizer 13, the main expansion valve 14, and the heat source side heat exchanger 15 connected in order. The use side heat exchanger 12 is connected to the heating medium pipe 101 and performs heat exchange between the water flowing through the heating medium pipe 101 and the refrigerant flowing through the main refrigerant circuit 10. The refrigeration cycle apparatus 1 includes the bypass refrigerant circuits 20, 30 that provide communication between the main refrigerant circuit 10 on the downstream side of the compressor 11 and the main refrigerant circuit 10 on the upstream side of the compressor 11, the bypass expansion valve 21 that is provided in the bypass refrigerant circuit 20, and opens and closes the bypass refrigerant circuit 20, the bypass two-way valve 31 that is provided in the bypass refrigerant circuit 30, and opens and closes the bypass refrigerant circuit 30, the water temperature sensor 42 that detects the temperature of the water flowing into the use side heat exchanger 12 from the heating medium pipe 101, the outside air temperature sensor 41, and the controller 50. The controller 50 opens the bypass expansion valve 21 and the bypass two-way valve 31 when recognizing that the compressor 11 is in the insufficient refrigerant discharge state in which the temperature detected by the water temperature sensor 42 is lower than the outside air temperature by Tth or more at the start of the compressor 11.
In the refrigeration cycle apparatus 1, when it is recognized that the compressor 11 is in the insufficient refrigerant discharge state at the start of the compressor 11, the amount of refrigerant suctioned into the compressor 11 can be increased by opening the bypass expansion valve 21 and the bypass two-way valve 31, thereby accelerating the circulation of the refrigerant. This makes it possible to restrain the internal temperature of the compressor 11 from excessively rising due to the refrigerant remaining in the compressor 11.

(Other Embodiments)

As above, the embodiment has been described as an example of the technique disclosed in the present application. However, the technique in the present disclosure is not limited thereto and is also applicable to embodiments with changes, replacements, additions, omissions, and the like.
In the above embodiment, in step S4 of FIG. 3, the controller 50 recognizes, as the insufficient refrigerant discharge state of the present disclosure, the state in which the temperature of the water flowing into the use side heat exchanger 12 is lower than the outside air temperature by the first predetermined temperature (Tth) or more. As another embodiment, a state in which the temperature of the water flowing into the use side heat exchanger 12 is lower than a saturation temperature of the refrigerant corresponding to the pressure detected by the discharge pressure sensor 40 by a second predetermined temperature or more may be recognized as the insufficient refrigerant discharge state in the present disclosure. For example, when the second predetermined temperature is 0°C and the saturation temperature of the refrigerant corresponding to the pressure of the refrigerant discharged from the compressor 11 is equal to or lower than the temperature of the water, the handling processes of step S5 and the subsequent steps in FIG. 3 may be executed. In this case, the controller 50 calculates the saturation temperature of the refrigerant corresponding to the pressure detected by the discharge pressure sensor 40 using a conversion table or a conversion formula for conversion between the pressure and the saturation temperature of the refrigerant contained in the control data stored in the memory 52. Alternatively, the insufficient refrigerant discharge state may be recognized using another condition based on the temperature of the water flowing into the use side heat exchanger 12.
In the above embodiment, in the flowchart of FIG. 3, the controller 50 may open the bypass expansion valve 21 and the bypass two-way valve 31 and adjust the opening degree of the main expansion valve 14 to a predetermined degree or more (e.g., fully open the main expansion valve 14) in steps S5 and S6. This makes it possible to further increase the amount of refrigerant suctioned into the compressor 11.
In the above embodiment, the configuration including the bypass refrigerant circuit 26 and the bypass two-way valve 27, and the bypass refrigerant circuit 30 and the bypass two-way valve 31 as the first bypass refrigerant circuit and the first bypass valve of the present disclosure is shown. However, only the bypass refrigerant circuit 26 and the bypass two-way valve 27, or only the bypass refrigerant circuit 30 and the bypass two-way valve 31 may be provided.
In addition, as shown in FIG. 4, in addition to the configuration shown in FIG. 1, a bypass refrigerant circuit 22 (corresponding to the second bypass refrigerant circuit of the present disclosure) that provides communication between the bypass refrigerant circuit 20 on the upstream side of the bypass expansion valve 21 and the bypass refrigerant circuit 20 on the downstream side of the bypass expansion valve 21, and a bypass two-way valve 23 (corresponding to the second bypass valve of the present disclosure) that is provided in the bypass refrigerant circuit 22, and opens and closes the bypass refrigerant circuit 22 may be provided. In this case, in step S5 of the flowchart in FIG. 3, the controller 50 opens the bypass expansion valve 21 and also opens the bypass two-way valve 23. This makes it possible to further increase the amount of refrigerant suctioned into the injection port 11a of the compressor 11 from the bypass refrigerant circuit 20.
Similarly, the bypass refrigerant circuit 30 may have a configuration that additionally includes a bypass refrigerant circuit 33 (corresponding to the second bypass refrigerant circuit of the present disclosure) that provides communication between the upstream side and the downstream side of the bypass two-way valve 31, and a bypass two-way valve 32 (corresponding to the second bypass valve of the present disclosure) that is provided in the bypass refrigerant circuit 33, and opens and closes the bypass refrigerant circuit 33. In this case, in step S6 of the flowchart in FIG. 3, the controller 50 opens the bypass two-way valve 31 and also opens the bypass two-way valve 32 additionally provided. This makes it possible to further increase the amount of refrigerant suctioned into the compressor 11 from the bypass refrigerant circuit 30.
In addition, as shown in FIG. 5, in addition to the configuration shown in FIG. 1, a bypass refrigerant circuit 24 that provides communication between the main refrigerant circuit 10 on the upstream side of the main expansion valve 14 and the main refrigerant circuit 10 on the downstream side of the main expansion valve 14, and a bypass two-way valve 25 that is provided in the bypass refrigerant circuit 24, and opens and closes the bypass refrigerant circuit 24 may be provided. In this case, in steps S5 and S6 of the flowchart in FIG. 3, the controller 50 opens the bypass expansion valve 21 and the bypass two-way valve 31, adjusts the main expansion valve 14 to a predetermined opening degree or more, and further opens the bypass two-way valve 25. This makes it possible to further increase the amount of refrigerant flowing into the compressor 11 from the refrigerant pipe 16.
In addition, as shown in FIG. 6, in the configuration shown in FIG. 1, the economizer 13 may be omitted, and a bypass refrigerant circuit 26 (corresponding to the first bypass refrigerant circuit of the present disclosure) that branches off from the main refrigerant circuit 10 between the use side heat exchanger 12 and the main expansion valve 14 and communicates with the main refrigerant circuit 10 on the upstream side of the compressor 11, and a bypass two-way valve 27 (corresponding to the first bypass valve of the present disclosure) that is provided in the bypass refrigerant circuit 26, and opens and closes the bypass refrigerant circuit 26 may be provided. In this case, in step S5 of the flowchart in FIG. 3, the controller 50 opens the bypass two-way valve 27 instead of the bypass expansion valve 21.
It is only required that the controller in the present disclosure be one that can control the apparatus in the present disclosure. In describing the subject matter of the invention, one that controls the apparatus of the present disclosure may be described as control means or a control unit, or described with similar wording, in addition to the controller. The controller can be implemented in various modes. For example, a processor may be used as the controller. Using the processor as the controller makes it possible to execute various processes by the processor reading a program from a storage medium in which the program is stored and executing the program. Thus, processing details can be changed by changing the program stored in the storage medium, and flexibility of changing control details can thus be increased. Examples of the processor include a central processing unit (CPU) and a micro-processing unit (MPU). Examples of the storage medium include a hard disk, a flash memory, and an optical disk. Wired logic that cannot be reprogrammed may be used as the controller. Using the wired logic as the controller is effective in improving the processing speed. An application specific integrated circuit (ASIC) is an example of the wired logic. The controller may be implemented by a combination of the processor and the wired logic. Implementing the controller by the combination of the processor and the wired logic makes it possible to improve the processing speed while increasing the flexibility of software design. The controller and a circuit having a function different from the function of the controller may be configured as a single semiconductor device. An A/D or D/A conversion circuit is an example of the circuit having the different function. The controller may be configured as a single semiconductor device or may include multiple semiconductor devices. When the controller includes multiple semiconductor devices, the control operations described in the claims may be achieved by semiconductor devices different from each other. Furthermore, the controller may have a configuration including a semiconductor device, and a passive component such as a resistor or a capacitor.
Since the embodiments described above are intended to exemplify the technique in the present disclosure, various changes, replacements, additions, omissions, and the like can be made within the scope of the claims or a scope equivalent thereto.

(Supplement)

The description of the above embodiments discloses the following techniques.
(Technique 1) A refrigeration cycle apparatus including: a main refrigerant circuit through which a refrigerant circulates, the main refrigerant circuit including a compressor, a use side heat exchanger, an expansion valve, and a heat source side heat exchanger connected in order, the use side heat exchanger being connected to a water pipe and being configured to perform heat exchange between water flowing through the water pipe and the refrigerant flowing through the main refrigerant circuit; a first bypass refrigerant circuit providing communication between the main refrigerant circuit on a downstream side of the compressor and the main refrigerant circuit on an upstream side of the compressor; a first bypass valve provided in the first bypass refrigerant circuit, the first bypass valve being configured to open and close the first bypass refrigerant circuit; a water temperature sensor configured to detect a temperature of the water flowing into the use side heat exchanger from the water pipe; and a controller configured to recognize an operating state of the compressor based on the temperature detected by the water temperature sensor at start of the compressor and bring the first bypass refrigerant circuit into an open state using the first bypass valve when recognizing that the compressor is in a predetermined insufficient refrigerant discharge state.
This configuration makes it possible to restrain the internal temperature of the compressor from excessively rising at the start of the compressor.
(Technique 2) The refrigeration cycle apparatus according to technique 1, further including an economizer connected to the main refrigerant circuit between the use side heat exchanger and the expansion valve, in which the compressor has an injection port communicating with a compression chamber, and the first bypass refrigerant circuit branches off from the main refrigerant circuit between the use side heat exchanger and the economizer and communicates with the injection port through the economizer.
With this configuration, the first bypass refrigerant circuit is brought into an open state at the start of the compressor, thereby allowing the high-pressure refrigerant affected by the water heat exchanger to be suctioned into the injection port of the compressor. This makes it possible to increase the amount of the refrigerant circulating and restrain a temperature rise in the mechanism part of the compressor.
(Technique 3) The refrigeration cycle apparatus according to technique 1 or 2, in which the main refrigerant circuit is installed outdoors, the refrigerant cycle apparatus further comprises an outside air temperature sensor configured to detect an outside air temperature, and the controller recognizes, as the insufficient refrigerant discharge state, a state in which the temperature detected by the water temperature sensor is higher than the temperature detected by the outside air temperature sensor by a first predetermined temperature or more.
With this configuration, the state in which the temperature detected by the water temperature sensor is higher than the temperature detected by the outside air temperature sensor by the first predetermined temperature or more is recognized as the state in which the discharge of the refrigerant from the compressor is insufficient, thereby making it possible to restrain the internal temperature of the compressor from excessively rising.
(Technique 4) The refrigeration cycle apparatus according to technique 1 or 2, further including a discharge pressure sensor configured to detect a pressure of the refrigerant discharged from the compressor, in which the controller recognizes, as the insufficient refrigerant discharge state, a state in which the temperature detected by the water temperature sensor is lower than a saturation temperature of the refrigerant corresponding to the pressure detected by the discharge pressure sensor by a second predetermined temperature or more.
With this configuration, the state in which the temperature detected by the water temperature sensor is lower than the saturation temperature of the refrigerant corresponding to the pressure detected by the discharge pressure sensor by the second predetermined temperature or more is recognized as the state in which the discharge of the refrigerant from the compressor is insufficient, thereby making it possible to restrain the internal temperature of the compressor from excessively rising.
(Technique 5) The refrigeration cycle apparatus according to any one of techniques 1 to 4, further including: a second bypass refrigerant circuit providing communication between the first bypass refrigerant circuit on an upstream side of the first bypass valve and the first bypass refrigerant circuit on a downstream side of the first bypass valve; and a second bypass valve provided in the second bypass refrigerant circuit, the second bypass valve being configured to open and close the second bypass refrigerant circuit, in which the controller brings the first bypass refrigerant circuit into an open state using the first bypass valve and brings the second bypass refrigerant circuit into an open state using the second bypass valve when recognizing that the compressor is in the insufficient refrigerant discharge state at start of the compressor.
With this configuration, at the start of the compressor, the second bypass refrigerant circuit is brought into an open state using the second bypass valve, thereby making it possible to increase the amount of refrigerant suctioned into the compressor and restrain the internal temperature of the compressor from rising.
(Technique 6) The refrigeration cycle apparatus according to any one of techniques 1 to 5, in which the expansion valve has an opening degree changing function, and the controller brings the first bypass refrigerant circuit into an open state using the first bypass valve and adjusts an opening degree of the expansion valve to a predetermined opening degree or more when recognizing that the compressor is in the insufficient refrigerant discharge state at start of the compressor.
With this configuration, at the start of the compressor, the opening degree of the expansion valve is adjusted to the predetermined opening degree or more, thereby making it possible to increase the amount of refrigerant suctioned into the compressor and restrain the internal temperature of the compressor from rising.

Industrial Applicability

The present disclosure is applicable to a use to restrain the internal temperature of a compressor from excessively rising at the start of the compressor.

Reference Signs List

1: refrigeration cycle apparatus
10: main refrigerant circuit
11: compressor
12: use side heat exchanger
13: economizer
14: main expansion valve
15: heat source side heat exchanger
16: refrigerant pipe
17: four-way valve
20: bypass refrigerant circuit
21: bypass expansion valve
30: bypass refrigerant circuit
31: bypass two-way valve
40: discharge pressure sensor
41: outside air temperature sensor
42: water temperature sensor
50: controller
60: remote control
100: use side heating medium circuit
101: heating medium pipe
102: feed pump

Claims

A refrigeration cycle apparatus characterized by comprising:
a main refrigerant circuit through which a refrigerant circulates, the main refrigerant circuit including a compressor (11), a use side heat exchanger (12), an expansion valve (14), and a heat source side heat exchanger (15) connected in order, the use side heat exchanger being connected to a water pipe and being configured to perform heat exchange between water flowing through the water pipe and the refrigerant flowing through the main refrigerant circuit;

a first bypass refrigerant circuit (20, 30) providing communication between the main refrigerant circuit on a downstream side of the compressor and the main refrigerant circuit on an upstream side of the compressor;

a first bypass valve (21, 31) provided in the first bypass refrigerant circuit, the first bypass valve being configured to open and close the first bypass refrigerant circuit;

a water temperature sensor (42) configured to detect a temperature of the water flowing into the use side heat exchanger from the water pipe; and

a controller (50) configured to recognize an operating state of the compressor based on the temperature detected by the water temperature sensor at start of the compressor and bring the first bypass refrigerant circuit into an open state using the first bypass valve when recognizing that the compressor is in a predetermined insufficient refrigerant discharge state.
The refrigeration cycle apparatus according to claim 1, further comprising an economizer (13) connected to the main refrigerant circuit between the use side heat exchanger and the expansion valve, wherein
the compressor has an injection port (11a) communicating with a compression chamber, and

the first bypass refrigerant circuit branches off from the main refrigerant circuit between the use side heat exchanger and the economizer and communicates with the injection port through the economizer.
The refrigeration cycle apparatus according to claim 1 or 2, wherein
the main refrigerant circuit is installed outdoors,

the refrigerant cycle apparatus further comprises an outside air temperature sensor (41) configured to detect an outside air temperature, and

the controller recognizes, as the insufficient refrigerant discharge state, a state in which the temperature detected by the water temperature sensor is higher than the temperature detected by the outside air temperature sensor by a first predetermined temperature (Tth) or more.
The refrigeration cycle apparatus according to claim 1 or 2, further comprising a discharge pressure sensor (40) configured to detect a pressure of the refrigerant discharged from the compressor, wherein
the controller recognizes, as the insufficient refrigerant discharge state, a state in which the temperature detected by the water temperature sensor is lower than a saturation temperature of the refrigerant corresponding to the pressure detected by the discharge pressure sensor by a second predetermined temperature or more.
The refrigeration cycle apparatus according to claim 1 or 2, further comprising:
a second bypass refrigerant circuit (22) providing communication between the first bypass refrigerant circuit on an upstream side of the first bypass valve and the first bypass refrigerant circuit on a downstream side of the first bypass valve; and

a second bypass valve (23) provided in the second bypass refrigerant circuit, the second bypass valve being configured to open and close the second bypass refrigerant circuit, wherein

the controller brings the first bypass refrigerant circuit into an open state using the first bypass valve and brings the second bypass refrigerant circuit into an open state using the second bypass valve when recognizing that the compressor is in the insufficient refrigerant discharge state at start of the compressor.
The refrigeration cycle apparatus according to claim 1 or 2, wherein
the expansion valve has an opening degree changing function, and

the controller brings the first bypass refrigerant circuit into an open state using the first bypass valve and adjusts an opening degree of the expansion valve to a predetermined opening degree or more when recognizing that the compressor is in the insufficient refrigerant discharge state at start of the compressor.