EP4692675A1

EP4692675A1 - Refrigeration cycle device

Info

Publication number: EP4692675A1
Application number: EP24780400.8A
Authority: EP
Inventors: Kosuke Takahashi; Hirotoshi Takeuchi; Yoshinari MAEMA; Kazuki KANEI; Haruki IRITANI
Original assignee: Fujitsu General Ltd
Current assignee: Fujitsu General Ltd
Priority date: 2023-03-28
Filing date: 2024-03-27
Publication date: 2026-02-11
Also published as: JP2024139877A; WO2024204294A1; JP7505615B1; CN120826575A; AU2024242074A1

Abstract

A refrigeration cycle device according to an embodiment of the present invention includes: a heat storage circuit including a bypass flow path that connects a discharge side of the compressor to a refrigerant pipe located between an outdoor heat exchanger and a main expansion valve, an auxiliary heat exchanger disposed in the bypass flow path and including a heat storage material capable of exchanging heat with part of a refrigerant discharged from the compressor, a first bypass expansion valve disposed in the bypass flow path between the compressor and the auxiliary heat exchanger, and a second bypass expansion valve disposed in the bypass flow path between the auxiliary heat exchanger and the refrigerant pipe; and a controller that controls the opening degree of the first bypass expansion valve on the basis of a change rate of a detection value of a pressure sensor that detects a pressure of the refrigerant on the discharge side of the compressor in a heat-storing and heating operation mode.

Description

Technical Field

The present invention relates to a refrigeration cycle device including a heat storage circuit.

Background Art

There is known a refrigeration cycle device that performs defrosting of an outdoor heat exchanger by using the heat stored in a heat storage material. This type of refrigeration cycle device includes a refrigerant circuit including a compressor, an outdoor heat exchanger, an indoor heat exchanger, and an expansion valve, as well as a heat storage circuit including a bypass flow path that connects the discharge side of the compressor to a liquid refrigerant pipe between the outdoor heat exchanger and the expansion valve, a heat storage tank that is disposed in the bypass flow path, and two bypass expansion valves that are disposed respectively on the upstream side and the downstream side of the heat storage tank (see, for example, Patent Literature 1).
The heat storage tank includes a heat storage material that is capable of exchanging heat with part of the refrigerant discharged from the compressor, and stores the heat of the refrigerant when the part of the refrigerant discharged from the compressor is introduced into the heat storage tank mainly during a heating operation (hereinafter, also referred to as a heat-storing and heating operation). In a defrosting operation, the indoor heat exchanger and the outdoor heat exchanger are caused to function as condensers, and the heat storage tank is caused to function as an evaporator by using the heat stored in the heat storage material. This makes it possible to perform a defrosting operation of the outdoor heat exchanger (hereinafter, also referred to as a defrosting and heating operation) without stopping the heating operation, thereby suppressing a reduction in heating capacity during the defrosting operation as well.

Citation List

Patent Literature

Patent Literature 1: Japanese Patent Application Laid-open No. 2016-17738

Disclosure of Invention

Technical Problem

In general, feedback control (FB control) and feedforward control (FF control) are known as control methods for the opening degree of the expansion valve. For the FB control, target discharge temperature control that is performed to adjust the flow rate of the entire refrigerant circuit, target subcooling control that is performed to adjust the flow rate to correspond to the capacity of the indoor unit, and the like are used. Meanwhile, the FF control is the control that aims at improvement in conformability, and is performed mainly on the basis of the rotation speed of the compressor. For example, the rotation speed of the compressor is increased along with an increase in heating capacity requested by the indoor unit, but in the FF control, the following control is performed, in which the opening degree of the expansion valve is increased so as to correspond to the increase rate of the rotation speed of the compressor such that the temperature of the refrigerant discharged from the compressor does not become too high.
However, Patent Literature 1 describes that each bypass expansion valve is opened in the heat-storing and heating operation to perform the heat-storing and heating operation, but it does not describe a control method for the opening degree of each bypass expansion valve when the heating capacity requested by the indoor unit is changed during the heat-storing and heating operation. Therefore, in the heat-storing and heating operation described in Patent Literature 1, assuming that the opening degree of the bypass expansion valve is controlled by the FF control as described above, when the rotation speed of the compressor is increased due to an increase in requested heating capacity, the opening degree of the bypass expansion valve is controlled to be increased. Thus, the refrigerant is supplied to the heat storage tank excessively, and the amount of refrigerant supplied to the indoor heat exchanger serving as a use-side heat exchanger is reduced more than the amount of refrigerant requested due to the increase in requested heating capacity. This may reduce the heating capacity (comfort). Further, in order to suppress the reduction in heating capacity as described above, it is necessary to excessively increase the rotation speed of the compressor. This causes an increase in power consumption, which is problematic.
In view of the circumstances as described above, it is an object of the present invention to provide a refrigeration cycle device that can suppress degradation of comfort and an increase in power consumption even if a requested heating capacity is changed during a heat-storing and heating operation. Solution to Problem
A refrigeration cycle device according to an embodiment of the present invention includes:

a refrigerant circuit including a compressor, an outdoor heat exchanger, an indoor heat exchanger, and a main expansion valve disposed between the outdoor heat exchanger and the indoor heat exchanger;
a heat storage circuit including a bypass flow path that connects a discharge side of the compressor to a refrigerant pipe located between the outdoor heat exchanger and the main expansion valve, an auxiliary heat exchanger disposed in the bypass flow path and including a heat storage material capable of exchanging heat with part of a refrigerant discharged from the compressor, a first bypass expansion valve disposed in the bypass flow path between the compressor and the auxiliary heat exchanger, and a second bypass expansion valve disposed in the bypass flow path between the auxiliary heat exchanger and the refrigerant pipe;
a pressure sensor that detects a pressure of the refrigerant on the discharge side of the compressor; and
a controller that controls opening degrees of the main expansion valve, the first bypass expansion valve, and the second bypass expansion valve, in which
the controller controls the opening degree of the first bypass expansion valve on the basis of a change rate of a detection value of the pressure sensor in a heat-storing and heating operation mode in which the indoor heat exchanger and the auxiliary heat exchanger are caused to function as condensers and the outdoor heat exchanger is caused to function as an evaporator.

In the heat-storing and heating operation mode, the controller may control the opening degree of the first bypass expansion valve such that the opening degree of the first bypass expansion valve is reduced when the change rate of the detection value of the pressure sensor has a positive value, and may control the opening degree of the first bypass expansion valve such that the opening degree of the first bypass expansion valve is increased when the change rate of the detection value of the pressure sensor has a negative value.
The controller may control the opening degree of the first bypass expansion valve on the basis of the detection value of the pressure sensor when the heat-storing and heating operation mode starts.
In the heat-storing and heating operation mode, the controller may control the opening degree of the second bypass expansion valve such that a subcooling of the refrigerant that flows out of the auxiliary heat exchanger is a target subcooling set in advance.
The controller may calculate a theoretical discharge temperature that is a discharge temperature when the refrigerant suctioned into the compressor is assumed as a saturated steam, and may control the opening degree of the main expansion valve such that a temperature of the refrigerant discharged from the compressor is the theoretical discharge temperature. Advantageous Effects of Invention
According to the present invention, it is possible to suppress degradation of comfort and an increase in power consumption even if a requested heating capacity is changed during a heat-storing and heating operation.

Brief Description of Drawings

[Fig. 1] Fig. 1 is a refrigerant circuit diagram of a refrigeration cycle device according to an embodiment of the present invention.
[Fig. 2] Fig. 2 is a block diagram showing a configuration of a control device in the refrigeration cycle device.
[Fig. 3] Fig. 3 is a flowchart showing an example of a processing procedure of a heat-storing and heating operation mode executed in the control device.
[Fig. 4] Fig. 4 is a timing diagram showing the operations or statuses of the respective sections of the refrigeration cycle device at the start of the heat-storing and heating operation mode.
[Fig. 5] Fig. 5 is a timing diagram showing the operations or statuses of the respective sections of the refrigeration cycle device during the execution of the heat-storing and heating operation mode.

Mode(s) for Carrying Out the Invention

An embodiment of the present invention will be described below with reference to the drawings.
Fig. 1 is a refrigerant circuit diagram of a refrigeration cycle device 100 according to an embodiment of the present invention. The refrigeration cycle device 100 in this embodiment is an air conditioner including an outdoor unit 2 and an indoor unit 3. Hereinafter, the details of the refrigeration cycle device 100 will be described.

[Configuration of Refrigeration Cycle Device]

The outdoor unit 2 includes a compressor 21 and an outdoor heat exchanger 22. The indoor unit 3 includes an indoor heat exchanger 23. The outdoor unit 2 and the indoor unit 3 are connected to each other by a gas pipe 12 and a liquid pipe 13. The refrigeration cycle device 100 includes a refrigerant circuit 20, a heat storage circuit 50, and a control device 90.

(Refrigerant Circuit)

The refrigerant circuit 20 includes the compressor 21, the outdoor heat exchanger 22, the indoor heat exchanger 23, and a main expansion valve 24 disposed between the outdoor heat exchanger 22 and the indoor heat exchanger 23.
The compressor 21 is a variable capacity compressor whose operating capacity can be varied by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. The discharge side of the compressor 21 is connected to a port a of a first four-way valve 41, which will be described later, by a discharge pipe 11. Further, the suction side of the compressor 21 is connected to the outlet side of an accumulator 25 via a suction pipe 16.
For example, various types of heat exchangers that can exchange heat between air and a refrigerant, such as a parallel flow heat exchanger, a fin tube heat exchanger, and a plate fin heat exchanger, can be adopted as the outdoor heat exchanger 22 and the indoor heat exchanger 23.
One refrigerant inlet/outlet of the outdoor heat exchanger 22 is connected to a port e of a second four-way valve 42, which will be described later, by a refrigerant pipe 14. The other refrigerant inlet/outlet of the outdoor heat exchanger 22 is connected to one refrigerant inlet/outlet of the indoor heat exchanger 23 via the main expansion valve 24 by the liquid pipe 13. The outdoor heat exchanger 22 functions as a condenser during a cooling operation and a defrosting and heating operation, and functions as an evaporator during a heating operation and a heat-storing and heating operation, by switching of the first four-way valve 41 and the second four-way valve 42. Note that an outdoor fan (not shown) that blows air to the outdoor heat exchanger 22 may be disposed near the outdoor heat exchanger 22.
One refrigerant inlet/outlet of the indoor heat exchanger 23 is connected to a port b of the first four-way valve 41, which will be described later, by the gas pipe 12. The other refrigerant inlet/outlet of the indoor heat exchanger 23 is connected to the other refrigerant inlet/outlet of the outdoor heat exchanger 22 via the main expansion valve 24 by the liquid pipe 13 as described above. The indoor heat exchanger 23 functions as an evaporator during the cooling operation, and functions as a condenser during the heating operation, the heat-storing and heating operation, and the defrosting and heating operation by switching of the first four-way valve 41 and the second four-way valve 42. Note that an indoor fan (not shown) that blows air to the indoor heat exchanger 23 may be disposed near the indoor heat exchanger 23.
The main expansion valve 24 is an electronic expansion valve whose opening degree is controlled on the basis of the pulse number given to a stepping motor (not shown), and is disposed in the liquid pipe 13 that connects the outdoor heat exchanger 22 and the indoor heat exchanger 23 to each other. The main expansion valve 24 is a pressure reducing valve that reduces the pressure of the refrigerant flowing through the liquid pipe 13. The opening degree of the main expansion valve 24 is adjusted in accordance with the heating capacity requested by the indoor unit 3 during the heating operation, and adjusted in accordance with the cooling capacity requested by the indoor unit 3 during the cooling operation.
The first four-way valve 41 and the second four-way valve 42 are flow path switching valves for switching the direction of the refrigerant flowing in the refrigerant circuit 20. The first four-way valve 41 and the second four-way valve 42 switch the connection of the one refrigerant inlet/outlet of the outdoor heat exchanger 22 to a refrigerant discharge port or a refrigerant suction port of the compressor 21.
The first four-way valve 41 includes four ports a, b, c, and d. The port a is connected to the discharge side of the compressor 21 by the discharge pipe 11. The port b is connected to the one refrigerant inlet/outlet of the indoor heat exchanger 23 by the gas pipe 12. The port c is connected to the inlet side of the accumulator 25 by a refrigerant pipe 15. The port d is connected to a junction B with a first bypass pipe 54 of the heat storage circuit 50 via a check valve 43 by a refrigerant pipe 17. The check valve 43 is a directional control valve that allows the refrigerant to flow from the port d toward the junction B and prohibits the reverse flow.
As will be described later, the first four-way valve 41 enters a first state in which the port a and the port b communicate with each other and the port c and the port d communicate with each other during the heating operation, the heat-storing and heating operation, and the defrosting and heating operation, as indicated by the solid lines in Fig. 1. Further, the first four-way valve 41 enters a second state in which the port a and the port d communicate with each other, and the port b and the port c communicate with each other during the cooling operation, as indicated by the broken lines in Fig. 1.
The second four-way valve 42 includes four ports e, f, g, and h. The port e is connected to the one refrigerant inlet/outlet of the outdoor heat exchanger 22 by the refrigerant pipe 14. The port f is connected to a branch point A of the discharge pipe by the first bypass pipe 54. The branch point A is provided between the discharge side of the compressor 21 and the port a of the first four-way valve 41. The port g is connected to one refrigerant inlet/outlet of an auxiliary heat exchanger 53 by the second bypass pipe 55. The port h is connected to a junction C of the refrigerant pipe 15. The junction C is provided between the port c of the first four-way valve 41 and the suction side of the accumulator 25.
As will be described later, the second four-way valve 42 enters a first state in which the port e and the port h communicate with each other and the port f and the port g communicate with each other during the heating operation and the heat-storing and heating operation, as indicated by the solid lines in Fig. 1. Further, the second four-way valve 42 enters a second state in which the port e and the port f communicate with each other, and the port g and the port h communicate with each other during the cooling operation and the defrosting and heating operation, as indicated by the broken lines in Fig. 1.
The inlet side of the accumulator 25 is connected to the port c of the first four-way valve 41 by the refrigerant pipe 15, and the outlet side thereof is connected to the suction side of the compressor 21 by the suction pipe 16. The accumulator 25 separates the refrigerant, which has flowed into the accumulator 25, into a gas refrigerant and a liquid refrigerant, and causes only the gas refrigerant to be suctioned into the compressor 21.

(Heat Storage Circuit)

The heat storage circuit 50 includes a first bypass expansion valve 51, a second bypass expansion valve 52, and the auxiliary heat exchanger 53 disposed between the first bypass expansion valve 51 and the second bypass expansion valve 52.
The first bypass expansion valve 51 and the second bypass expansion valve 52 are electronic expansion valves whose opening degree is controlled on the basis of the pulse number given to a stepping motor (not shown). The first bypass expansion valve 51 is disposed in the first bypass pipe 54 located between the branch point A of the discharge pipe 11 and the junction B of the refrigerant pipe 17. The second bypass expansion valve 52 is disposed in a third bypass pipe 56 that connects the other refrigerant inlet/outlet of the auxiliary heat exchanger 53 and a junction D of the liquid pipe 13.
Note that the first bypass pipe 54, the second bypass pipe 55, and the third bypass pipe 56 form a bypass flow path of the present invention, which connects the discharge side of the compressor 21 to a refrigerant pipe (the junction D of the liquid pipe 13) between the outdoor heat exchanger 22 and the main expansion valve 24.
The auxiliary heat exchanger 53 is disposed in the second bypass pipe 55. The one refrigerant inlet/outlet of the auxiliary heat exchanger 53 is connected to the port g of the second four-way valve 42 by the second bypass pipe 55, and the other refrigerant inlet/outlet of the auxiliary heat exchanger 53 is connected to the junction D of the liquid pipe 13 via the second bypass expansion valve 52 by the third bypass pipe 56.
The auxiliary heat exchanger 53 includes a heat storage material 57 that can exchange heat with part of the refrigerant discharged from the compressor 21. For example, a metallic block material with excellent thermal conductivity, such as copper or aluminum, is used for the heat storage material 57. In addition to those above, a liquid or slurry phase-change substance that can store heat by heat exchange with the refrigerant flowing through the auxiliary heat exchanger 53 may also be used as the heat storage material. Further, the amount of heat stored in the heat storage material 57 is not limited as long as the auxiliary heat exchanger 53 can store enough heat to evaporate the refrigerant flowing in from the outdoor heat exchanger 22 and the indoor heat exchanger 23 during the defrosting and heating operation, which will be described later.
Various sensors are provided in the outdoor unit 2. In this embodiment, as shown in Fig. 1, the discharge pipe 11 is provided with a discharge pressure sensor 71 that detects a discharge pressure, which is the pressure of the refrigerant discharged from the compressor 21, and a discharge temperature sensor 73 that detects a discharge temperature, which is the temperature of the refrigerant discharged from the compressor 21. The suction pipe 16 is provided with a suction pressure sensor 72 that detects a suction pressure, which is the pressure of the refrigerant suctioned into the compressor 21, and a suction temperature sensor 74 that detects a suction temperature, which is the temperature of the refrigerant suctioned into the compressor 21.
The outdoor heat exchanger 22 is provided with an outdoor heat exchange temperature sensor 75 that detects an outdoor heat exchange temperature, which is the temperature of the outdoor heat exchanger 22. Further, an outside air temperature sensor 76 that detects a temperature of outside air flowing into the casing (not shown) of the outdoor unit 2, i.e., an outside air temperature, is provided near a suction port (not shown) of the outdoor unit 2.
Meanwhile, for the indoor unit 3, a gas-side temperature sensor 77 is provided on the one refrigerant inlet/outlet side of the indoor heat exchanger 23 in the gas pipe 12, and a liquid-side temperature sensor 78 is provided on the other refrigerant inlet/outlet side of the indoor heat exchanger 23 in the liquid pipe 13. Further, a roomtemperature sensor 79 that detects a temperature of indoor air flowing into the indoor unit 3, i.e., a room temperature, is provided near a suction port (not shown) of the indoor unit 3.
Furthermore, a heat storage circuit temperature sensor 80 that detects the temperature of the heat storage material 57 is provided in the heat storage circuit 50.

(Control Device)

The control device 90 is, for example, an outdoor unit control device provided to the outdoor unit 2, and is mounted on a control board stored in an electrical equipment box (not shown) of the outdoor unit 2. The control device 90 corresponds to a controller of the present invention.
Fig. 2 is a block diagram showing a configuration of the control device 90. As shown in the figure, the control device 90 includes a CPU 91, a storage section 92, a communication section 93, a sensor input section 94, and a rotation speed detection section 95.
The storage section 92 is a nonvolatile memory such as a flash memory, and stores control programs or control parameters of the outdoor unit 2, detection values corresponding to detection signals from various sensors, control states of the compressor 21, the outdoor fan, etc., the rotation speed of the indoor fan acquired via the communication section 93, control states of the indoor unit 3 that include a drive mode that has been set and input by a user, and the like.
The communication section 93 is an interface that communicates with the indoor unit 3. The sensor input section 94 takes in detection results of the various sensors of the outdoor unit 2 and outputs them to the CPU 91. The rotation speed detection section 95 detects the rotation speed of the motor of the compressor 21 and outputs it to the CPU 91. The rotation speed detection section 95 may be configured to directly detect the rotation speed of the motor by using an encoder or the like attached to the drive shaft of the motor, or may be configured to detect the rotation speed of the motor from a drive current supplied from the motor. In the following description, the rotation speed of the compressor 21 refers to the rotation speed of the motor.
The CPU 91 is a controller that controls the drive of the sections of the outdoor unit 2 including the compressor 21 by executing the programs stored in the storage section 92. The programs are installed in the control device 90, for example, via various recording media. Alternatively, the programs may be installed via the Internet or the like.
The CPU 91 takes in the detection results of the sensors of the above-mentioned outdoor unit 2 via the sensor input section 94. Further, the CPU 91 takes in the control signals transmitted from the indoor unit 3 via the communication section 93. The control signals transmitted from the indoor unit 3 include a required drive capacity (the thermal load of the indoor unit 3) requested from the indoor unit 3c, and the like. The CPU 91 controls the drive of the compressor 21, the outdoor fan, and the indoor fan, for example, sets a specified rotation speed that is a rotation speed for driving those components, on the basis of the taken-in detection results or control signals. Further, the CPU 91 performs switching control of the first four-way valve 41 and the second four-way valve 42 on the basis of the taken-in detection results or control signals. In addition, the CPU 91 controls the rotation speeds of the compressor 21 and the outdoor fan and controls the opening degrees of the main expansion valve 24, the first bypass expansion valve 51, and the second bypass expansion valve 52 on the basis of the taken-in detection results or control signals.

[Basic Operation of Refrigeration Cycle Device]

Subsequently, the basic operation of the refrigeration cycle device 100 will be described. The refrigeration cycle device 100 (control device 90) of this embodiment can execute four drive modes shown in Table 1.

[Table 1]

No.	Operation mode	First four-way valve (41)	Second four-way valve (42)	Main expansion valve (24)	First bypass expansion valve (51)	Second bypass expansion valve (52)
1	Cooling operation	Second state a-d, b-c connected	Second state e-f, g-h connected	Controlled	Fully opened	Fully closed
2	Heating operation	First state a-b, c-d connected	First state e-h, f-g connected	Controlled	Fully closed	Small opening degree
3	Heat-storing and heating operation	First state a-b, c-d connected	First state e-h, f-g connected	Controlled	Controlled	Controlled
4	Defrosting and heating operation	First state a-b, c-d connected	Second state e-f, g-h connected	Controlled	Controlled	Fully opened

(1: Cooling Operation)

In the cooling operation mode, the first four-way valve 41 is switched to the second state (a-d connected, b-c connected), and the second four-way valve 42 is switched to the second state (e-f connected, g-h connected). The opening degree of the main expansion valve 24 is feedback controlled such that the temperature of the refrigerant discharged from the compressor 21 is a target discharge temperature. The first bypass expansion valve 51 is fully opened, and the second bypass expansion valve 52 is fully closed. In the cooling operation mode, the outdoor heat exchanger 22 is caused to function as a condenser, and the indoor heat exchanger 23 is caused to function as an evaporator.
Here, the target discharge temperature refers to a theoretical discharge temperature that is a discharge temperature when the refrigerant suctioned into the compressor 21 is assumed to be a saturated steam. The theoretical discharge temperature is a discharge temperature when the refrigerant suctioned into the compressor 21 is assumed to be a saturated steam (dryness of 1), calculated on the basis of the discharge pressure and the suction pressure, and means a discharge temperature when adjusted to an ideal cooling cycle. Parameters for calculating the theoretical discharge temperature may include the rotation speed of the compressor 11, in addition to the discharge pressure and the suction pressure. The opening degree of the main expansion valve 24 is controlled such that the temperature of the refrigerant discharged from the compressor 21 is the theoretical discharge temperature, so that it is possible to adjust the dryness of the refrigerant suctioned into the compressor 21 to 1 in accordance with the change in rotation speed of the compressor 21. This makes it possible to prevent the reliability of the compressor from being reduced.
The high-pressure gas refrigerant discharged from the compressor 21 is divided, at the branch point A of the discharge pipe 11, into the refrigerant flowing through the first four-way valve 41 and the refrigerant flowing through the first bypass pipe 54 via the first bypass expansion valve 51. The high-pressure gas refrigerant flowing through the first four-way valve 41 flows into the first bypass pipe 54 via the refrigerant pipe 17, the check valve 43, and the junction B, and flows into the refrigerant pipe 14 via the second four-way valve 42. The high-pressure gas refrigerant flowing into the refrigerant pipe 14 exchanges heat with the outdoor air in the outdoor heat exchanger 22, which functions as a condenser, condenses to be a high-pressure liquid refrigerant, and flows into the liquid pipe 13. Note that normally the first bypass expansion valve 51 is fully opened from the viewpoint of preventing backflow, but if the check valve 43 is provided to the refrigerant pipe 17 as in this embodiment, the first bypass expansion valve 51 may be fully closed.
The intermediate-pressure liquid refrigerant that has flowed into the liquid pipe 13 is reduced in pressure by the main expansion valve 24 to be a low-pressure liquid refrigerant and flows into the indoor heat exchanger 23. Since the second bypass expansion valve 52 is fully closed, the liquid refrigerant is inhibited from flowing into the heat storage circuit 50 from the junction D of the liquid pipe 13. The low-pressure liquid refrigerant that has flowed into the indoor heat exchanger 23 functioning as an evaporator exchanges heat with the indoor air, evaporates to be a low-pressure gas refrigerant, and flows into the gas pipe 12. Thus, the room in which the indoor unit 3 is installed is cooled. The low-pressure gas refrigerant that has flowed into the gas pipe 12 flows into the accumulator 25 via the first four-way valve 41 and the refrigerant pipe 15 and is suctioned into the compressor 21 via the suction pipe 16.

(2: Heating Operation)

In the heating operation mode, the first four-way valve 41 is switched to the first state (a-b connected, c-d connected), and the second four-way valve 42 is switched to the first state (e-h connected, f-g connected). The opening degree of the main expansion valve 24 is feedback controlled such that the temperature of the refrigerant discharged from the compressor 21 is a target discharge temperature. The first bypass expansion valve 51 is fully closed, and the opening degree of the second bypass expansion valve 52 is reduced to the extent that the retention of the refrigerant in the heat storage circuit 50 can be prevented. In the heating operation mode, the outdoor heat exchanger 22 is caused to function as an evaporator, and the indoor heat exchanger 23 is caused to function as a condenser.
The high-pressure gas refrigerant discharged from the compressor 21 flows into the indoor heat exchanger 23 via the discharge pipe 11, the first four-way valve 41, and the gas pipe 12. Since the first bypass expansion valve 51 is fully closed, the gas refrigerant is inhibited from flowing into the heat storage circuit 50 from the branch point A of the discharge pipe 11. The high-pressure gas refrigerant that has flowed into the indoor heat exchanger 23 functioning as a condenser exchanges heat with the indoor air, condenses to be a high-pressure liquid refrigerant, and flows into the liquid pipe 13. Thus, the room in which the indoor unit 3 is installed is heated.
The intermediate-pressure liquid refrigerant that has flowed into the liquid pipe 13 is reduced in pressure by the main expansion valve 24 to be a low-pressure liquid refrigerant and flows into the outdoor heat exchanger 22. Since the pressure of the refrigerant remaining in the heat storage circuit 50 is higher than the pressure of the refrigerant at the junction D of the liquid pipe 13 on the downstream side of the main expansion valve 24, the refrigerant remaining in the heat storage circuit 50 joins at the junction D of the liquid pipe 13 due to the pressure difference by passing through the second bypass expansion valve 52 adjusted to have the above-mentioned predetermined opening degree. The low-pressure liquid refrigerant that has flowed into the outdoor heat exchanger 22 functioning as an evaporator exchanges heat with the outside air, evaporates to be a low-pressure gas refrigerant, and flows into the refrigerant pipe 14. The low-pressure gas refrigerant that has flowed into the refrigerant pipe 14 flows into the accumulator 25 via the second four-way valve 42 and the refrigerant pipe 15 and is suctioned into the compressor 21 via the suction pipe 16.

(3: Heat-Storing and Heating Operation)

In the heat-storing and heating operation mode, the first four-way valve 41 is switched to the first state (a-b connected, c-d connected), and the second four-way valve 42 is switched to the first state (e-h connected, f-g connected). The opening degree of the main expansion valve 24 is feedback controlled such that the temperature of the refrigerant discharged from the compressor 21 is a target discharge temperature. The opening degree of the first bypass expansion valve 51 is controlled such that a temperature difference between the temperature of the refrigerant flowing through the auxiliary heat exchanger 53 and the temperature of the heat storage material 57 is a predetermined temperature difference, and in this embodiment, is controlled in accordance with the change in pressure (high pressure) on the inlet side of the first bypass expansion valve when a requested heating capacity is changed, as will be described later. The opening degree of the second bypass expansion valve 52 is a fixed value, or is feedback controlled such that a subcooling (the degree of supercooling) of the refrigerant flowing out of the auxiliary heat exchanger 53 is a target subcooling. In the heat-storing and heating operation mode, the outdoor heat exchanger 22 is caused to function as an evaporator, and the indoor heat exchanger 23 and the auxiliary heat exchanger 53 are caused to function as condensers.
The high-pressure gas refrigerant discharged from the compressor 21 is divided, at the branch point A of the discharge pipe 11, into the refrigerant flowing through the first four-way valve 41 and the refrigerant flowing through the first bypass pipe 54 via the first bypass expansion valve 51. The high-pressure gas refrigerant flowing through the first four-way valve 41 flows into the indoor heat exchanger 23 functioning as a condenser via the gas pipe 12, exchanges heat with the indoor air, condenses to be a high-pressure liquid refrigerant, and flows into the liquid pipe 13. Thus, the room in which the indoor unit 3 is installed is heated. The intermediate-pressure liquid refrigerant that has flowed into the liquid pipe 13 is reduced in pressure by the main expansion valve 24 to be a low-pressure liquid refrigerant and flows into the outdoor heat exchanger 22.
Meanwhile, the high-pressure gas refrigerant that has flowed into the first bypass pipe 54 flows into the auxiliary heat exchanger 53 via the second four-way valve 42 and the second bypass pipe 55. The auxiliary heat exchanger 53 functions as a condenser, and the high-pressure gas refrigerant that has flowed into the auxiliary heat exchanger 53 exchanges heat with the heat storage material 57, condenses to be a high-pressure liquid refrigerant, and flows into the third bypass pipe 56. Thus, heat is stored in the heat storage material 57. The intermediate-pressure liquid refrigerant that has flowed into the third bypass pipe 56 is reduced in pressure by the second bypass expansion valve 52 to be a low-pressure liquid refrigerant. The low-pressure liquid refrigerant that has been reduced in pressure by the second bypass expansion valve 52 joins the low-pressure liquid refrigerant that has been reduced in pressure by the main expansion valve 24 at the junction D of the liquid pipe 13, and flows into the outdoor heat exchanger 22.
The outdoor heat exchanger 22 functions as an evaporator, and the low-pressure liquid refrigerant that has flowed into the outdoor heat exchanger 22 exchanges heat with the outside air, evaporates to be a low-pressure gas refrigerant, and flows into the refrigerant pipe 14. The low-pressure gas refrigerant that has flowed into the refrigerant pipe 14 flows into the accumulator 25 via the second four-way valve 42 and the refrigerant pipe 15 and is suctioned into the compressor 21 via the suction pipe 16.
The heat-storing and heating operation mode is a drive mode for causing the heat storage material 57 to store the heat of the refrigerant in order to cause the auxiliary heat exchanger 53 to function as a heat source-side heat exchanger in the defrosting and heating operation mode, which will be described later, while maintaining an indoor heating function. Typically, the heat-storing and heating operation mode is switched automatically from the heating operation mode in accordance with the outside air temperature or the like. For example, when the outside air temperature is low enough to be likely to frost on the outdoor heat exchanger 22, the mode is switched to the heat-storing and heating operation mode. On the other hand, if the outside air temperature rises to the extent that there is no possibility of frosting during the heat-storing and heating operation, the mode may be automatically switched to the heating operation mode.
Further, during the heat-storing and heating operation, when it is determined on the basis of the detection value of the storage circuit temperature sensor 80 that the heat storage material 57 has reached the temperature set in advance that is a sufficient amount of heat enough to perform the defrosting and heating operation, the mode may be automatically switched from the heat-storing and heating operation mode to the heating operation mode. Alternatively, when the amount of stored heat of the heat storage material 57 is reduced during the heating operation and when it is determined that the temperature of the heat storage material 57 falls below the above-mentioned temperature by a predetermined temperature or more, the mode may be automatically switched from the heating operation mode to the heat-storing and heating operation mode.

(4: Defrosting and Heating Operation)

In the defrosting and heating operation mode, the first four-way valve 41 is switched to the first state (a-b connected, c-d connected), and the second four-way valve 42 is switched to the second state (e-f connected, g-h connected). The opening degree of the main expansion valve 24 is feedback controlled such that the temperature of the refrigerant discharged from the compressor 21 is a target discharge temperature. The opening degree of the first bypass expansion valve 51 is fixed to a predetermined opening degree that can ensure the flow rate of the refrigerant necessary to complete the defrosting of the outdoor heat exchanger 22, and the second bypass expansion valve 52 is fully opened. In the defrosting and heating operation mode, the outdoor heat exchanger 22 and the indoor heat exchanger 23 are caused to function as condensers, and the auxiliary heat exchanger 53 is caused to function as an evaporator.
The high-pressure gas refrigerant discharged from the compressor 21 is divided, at the branch point A of the discharge pipe 11, into the refrigerant flowing through the first four-way valve 41 and the refrigerant flowing through the first bypass pipe 54 via the first bypass expansion valve 51. The high-pressure gas refrigerant flowing through the first four-way valve 41 flows into the indoor heat exchanger 23 functioning as a condenser via the gas pipe 12, exchanges heat with the indoor air, condenses to be a high-pressure liquid refrigerant, and flows into the liquid pipe 13. Thus, the room in which the indoor unit 3 is installed is heated. The intermediate-pressure liquid refrigerant that has flowed into the liquid pipe 13 is reduced in pressure by the main expansion valve 24 to be a low-pressure liquid refrigerant.
Meanwhile, the high-pressure gas refrigerant that has flowed into the first bypass pipe 54 flows into the outdoor heat exchanger 22 functioning as a condenser via the second four-way valve 42 and the refrigerant pipe 14. The high-pressure gas refrigerant that has flowed into the outdoor heat exchanger 53 exchanges heat with the frost attached to the outdoor heat exchanger 22, condenses to be a high-pressure liquid refrigerant, and flows into the liquid pipe 13. Thus, the frost attached to the outdoor heat exchanger 22 is melted by the heat of the refrigerant and removed. The intermediate-pressure liquid refrigerant that has flowed into the liquid pipe 13 flows into the auxiliary heat exchanger 53 from the junction D of the liquid pipe 13 together with the low-pressure liquid refrigerant that has been reduced in pressure by the main expansion valve 24, via the third bypass pipe 56 and the second bypass expansion valve 52.
The auxiliary heat exchanger 53 functions as an evaporator. The low-pressure, gas-liquid two-phase refrigerant that has flowed into the auxiliary heat exchanger 53 exchanges heat with the heat stored in the heat storage material 57, evaporates to be a low-pressure gas refrigerant, and flows into the second bypass pipe 55. The low-pressure gas refrigerant that has flowed into the second bypass pipe 55 flows into the accumulator 25 via the second four-way valve 42 and the refrigerant pipe 15 and is suctioned into the compressor 21 via the suction pipe 16.
In the defrosting and heating operation mode, the defrosting operation of the outdoor unit can be performed without stopping the heating operation, which makes it possible to suppress deterioration of the heating function in the room during the period for the defrosting operation.

[Problems in Heat-Storing And Heating Operation Mode]

In the refrigeration cycle device with the heat-storing and heating operation mode, the following problems arise as a control method for the first bypass expansion valve 51 that adjusts the flow rate of the refrigerant flowing through the heat storage circuit 50 when the above-mentioned heat-storing and heating operation mode is executed.
In general, feedback control (FB control) and feedforward control (FF control) are known as control methods for expansion valves. The FB control is the control to compare the current value with a target value to make the current value match the target value, and includes, for example, target discharge temperature control that is performed to adjust the flow rate of the entire refrigerant circuit, and target subcooling control that is performed to adjust the flow rate to correspond to the capacity of the indoor unit. Meanwhile, the FF control is the control that aims at improvement in conformability and is performed mainly on the basis of the rotation speed of the compressor. For example, when the rotation speed of the compressor is increased as the heating capacity requested by the indoor unit increases, the FF control is performed to increase the opening degree of the expansion valve to correspond to the increase rate of the rotation speed of the compressor such that the temperature of the refrigerant discharged from the compressor does not become too high.
Here, assuming that the opening degree of the first bypass expansion valve 51 is controlled by the FF control as described above, when the rotation speed of the compressor 21 is increased due to an increase in requested heating capacity, the opening degree of the first bypass expansion valve 51 is controlled to be increased, so that an excessive amount of refrigerant is supplied to the auxiliary heat exchanger 53 serving as a heat storage tank. This may reduce the amount of refrigerant supplied to the indoor heat exchanger 23, which is the use-side heat exchanger, to be less than the amount of refrigerant requested due to the increase in the requested heating capacity, resulting in a decrease in heating capacity (comfort). Further, in order to suppress such a decrease in heating capacity, it is necessary to raise the rotation speed of the compressor 21 excessively, which causes a problem in that power consumption is increased.

[Details of This Embodiment]

In this regard, in this embodiment, in order to suppress degradation of comfort and an increase in power consumption even when the requested heating capacity is changed during the heat-storing and heating operation, the first bypass expansion valve 51 is controlled as follows. Hereinafter, the details of the processing performed by the control device 90 in the heat-storing and heating operation mode will be described. Here, the case where the mode is switched from the heating operation mode to the heat-storing and heating operation mode will be described as an example.
Fig. 3 is a flowchart showing an example of a processing procedure of the heat-storing and heating operation mode performed in the control device 90. Fig. 4 is an example of a timing diagram showing the operations or statuses of the respective sections of the refrigeration cycle device 100 at the start of the heat-storing and heating operation mode, in which (A) shows the rotation speed of the compressor 21, (B) shows a condensation pressure of the refrigerant in the indoor heat exchanger 23 (high pressure in the refrigerant circuit 20), and (C) shows the opening degree (pulse number) of the first bypass expansion valve 51. Fig. 5 is an example of a timing diagram showing the operations or statuses of the respective sections of the refrigeration cycle device 100 during the execution of the heat-storing and heating operation mode, in which (A) shows the rotation speed of the compressor 21, (B) shows a condensation pressure of the refrigerant in the indoor heat exchanger 23 (high pressure in the refrigerant circuit 20), (C) shows the opening degree (pulse number) of the first bypass expansion valve 51, (D) shows a pressure of the refrigerant in the auxiliary heat exchanger 53 (high pressure in the heat storage circuit 50), (E) shows the flow rate of the refrigerant flowing through the indoor unit 3, and (F) shows the flow rate of the refrigerant flowing through the heat storage circuit 50.
When the heat-storing and heating operation mode is performed, the control device 90 adjusts the opening degree of the first bypass expansion valve 51 on the basis of the pressure of the refrigerant on the discharge side of the compressor 21. Here, the pressure of the refrigerant on the discharge side of the compressor 21 means the pressure on the high-pressure side of the refrigerant circuit 20 or the pressure of the refrigerant in the auxiliary heat exchanger 53 of the heat storage circuit 50, and in this embodiment, is a discharge pressure that is the pressure on the inlet side of the first bypass expansion valve 51. Such a pressure value is detected by the discharge pressure sensor 71. Hereinafter, the pressure of the refrigerant on the discharge side of the compressor 21 will also be referred to simply as "high pressure of the refrigerant".
As shown in Fig. 4, when the heat-storing and heating operation mode starts at time T1, the control device 90 detects the current high pressure of the refrigerant (ST101), and calculates the amount of controlling the opening degree for setting the opening degree of the first bypass expansion valve 51 on the basis of the value of the detected high pressure of the refrigerant (ST102).
In the normal opening degree control of the first bypass expansion valve 51, the opening degree is adjusted such that a temperature difference between the temperature of the refrigerant flowing through the auxiliary heat exchanger 53 and the temperature of the heat storage material 57 is a predetermined temperature difference. However, since the amount of refrigerant flowing into the indoor heat exchanger 23 from the compressor 21 is reduced when the first bypass expansion valve 51 is opened, there is a possibility that the heating capacity of the indoor unit 3 is temporarily largely reduced at the start of the heat-storing and heating operation.
In this regard, in this embodiment, in order to suppress the degradation of comfort (heating capacity) in the room at the start of the heat-storing and heating operation, the current high pressure of the refrigerant is detected before the first bypass expansion valve 51 is opened, and the amount of controlling the opening degree of the first bypass expansion valve is corrected on the basis of the detection value (ST102). Specifically, for example, when the high pressure of the refrigerant is equal to or larger than a threshold set in advance, the amount of controlling the opening degree of the first bypass expansion valve 51 is calculated to obtain the opening degree set in advance in accordance with the rotation speed of the compressor 21 without correcting the amount of controlling the opening degree. When the high pressure of the refrigerant is below the above threshold, the amount of controlling the opening degree of the first bypass expansion valve 51 is calculated such that the opening degree after correction is smaller than the opening degree before correction (that is, without correction). The correction amount of the amount of controlling the opening degree may be a fixed value or may be set to be variable in accordance with the detection value of the high pressure.
Subsequently, the control device 90 adjusts the opening degree of the first bypass expansion valve 51 on the basis of the calculated amount of controlling the opening degree (ST103). Thus, the first bypass expansion valve 51 is opened (time T2 of Fig. 4), and the opening degree is increased stepwise toward a target opening degree determined by the calculated amount of controlling the opening degree. Further, as the opening degree of the first bypass expansion valve 51 increases, the refrigerant pressure (condensation pressure) in the indoor heat exchanger 23 decreases, but the pressure by which the heating capacity necessary to maintain the comfort in the room can be obtained can be ensured.
Subsequently, the control device 90 determines whether or not there is a change in required drive capacity that is requested from the indoor unit 3 (hereinafter, also referred to as requested heating capacity) at predetermined time intervals (ST104). If an instruction to change the heating capacity requested by the indoor unit 3 is confirmed (Yes in ST104), the control device 90 changes the rotation speed of the compressor 21 to be the rotation speed corresponding to the requested heating capacity that has been changed, but in this embodiment, the change rate of the high pressure of the refrigerant before and after the change in rotation speed of the compressor 21 is calculated. The change rate of the high pressure of the refrigerant is calculated on the basis of the change rate of the detection value of the discharge pressure sensor 71.
Note that there is no instruction to change the requested heating capacity (No in ST104), the opening degree of the first bypass expansion valve 51 is controlled such that the difference between the temperature of the refrigerant on the inlet side of the first bypass expansion valve 51 (detection value of the discharge temperature sensor 73) and the temperature of the heat storage material 57 (detection value of the heat storage circuit temperature sensor 80) becomes constant.
As shown in Fig. 5, if an instruction to change the requested heating capacity is received at time T3, the control device 90 detects the current (time T3) high pressure of the refrigerant before the change in rotation speed of the compressor 21, and stores it in the storage section 92 (ST105).
Subsequently, at time T4, the control device 90 changes the rotation speed of the compressor 21 to be a target rotation speed corresponding to the requested heating capacity that has been changed (ST106). Although the case where the requested heating capacity increases is described here as an example, in this case, the rotation speed of the compressor 21 is increased to obtain a rotation speed corresponding to the amount of increase (or increase rate) of the requested heating capacity. Note that if the requested heating capacity decreases, the rotation speed of the compressor 21 is reduced to obtain a rotation speed corresponding to the amount of decrease (or decrease rate) thereof.
As the rotation speed of the compressor 21 increases, the discharge pressure of the compressor 21 increases, so that the flow rate and pressure of the refrigerant flowing through the indoor heat exchanger 23 and the flow rate and pressure of the refrigerant flowing through the heat storage circuit 50 both increase (see (B) and (D) to (F) of Fig. 5). When the rotation speed of the compressor 21 reaches the target rotation speed, the control device 90 detects the current (time T5) high pressure of the refrigerant after the change in rotation speed of the compressor 21, and stores it in the storage section 92 (ST107).
Subsequently, the control device 90 calculates the amount of controlling the opening degree of the first bypass expansion valve 51 on the basis of the change rate of the high pressures of the refrigerant detected in ST105 and ST107 (ST108). Here, when the detection value of the high pressure before the rotation speed of the compressor 21 is changed, which has been detected in ST105, is assumed as P1 and the detection value of the high pressure after the rotation speed of the compressor 21 is changed, which has been detected in ST107, is assumed as P2, the value calculated by the formula (P2-P1)/P1 is defined as the above-mentioned change rate of the high pressure.
Here, the timing for detecting the detection value P1 is, for example, the timing when it is determined that there is an instruction to change the requested heating capacity in ST104. Further, the timing for detecting the detection value P2 is, for example, the timing when a predetermined period set in advance has elapsed after the start of the control of changing the rotation speed of the compressor 21, the predetermined period being necessary for the rotation speed of the compressor 21 to reach the target rotation speed. Note that the present invention is not limited to the above, and the detection value of the discharge pressure sensor 71 may be acquired in every predetermined cycle (for example, one minute). In this case, the detection value acquired immediately after the start of control of changing the rotation speed of the compressor 21 is set as P1, and the detection value acquired immediately after the rotation speed of the compressor 21 reaches the target rotation speed is set as P2.
When the change rate of the detection value of the high pressure is positive, the control device 90 calculates the opening degree amount of the first bypass expansion valve 51 such that the opening degree of the first bypass expansion valve 51 is reduced. The example shown in Fig. 5 shows the case where the high pressure increases due to the increase in the rotation speed of the compressor 21, and thus the change rate of the detection value of the high pressure is positive. Therefore, the opening degree of the first bypass expansion valve 51 is controlled such that the opening degree of the first bypass expansion valve 41 is reduced (ST109, time T6).
Thus, the amount and pressure of the refrigerant flowing into the heat storage circuit 50 decrease (see (D) and (G) of Fig. 5). As a result, the flow rate and pressure of the refrigerant flowing into the indoor heat exchanger 23 increase (see (B) and (E) of Fig. 5), so that the degradation of comfort in the room due to an insufficient heating capacity is suppressed.
Note that when the requested heating capacity decreases, the change rate of the detection value of the high pressure is negative because the rotation speed of the compressor 21 decreases. In this case, the opening degree of the first bypass expansion valve 51 is controlled to be increased. Thus, the amount and pressure of the refrigerant flowing into the heat storage circuit 50 increase, and the flow rate and pressure of the refrigerant flowing into the indoor heat exchanger 23 decrease.
After that, the processing of ST104 to ST109 are repeated in a predetermined cycle. This makes it possible to continue supplying the amount of refrigerant required for the heat storage circuit 50 while suppressing the degradation of comfort in the room during the heat-storing and heating operation.
As described above, according to this embodiment, the opening degree of the first bypass expansion valve 51 is controlled on the basis of the change rate of the detection value of the high pressure of the refrigerant detected by the discharge pressure sensor 71 in the heat-storing and heating operation mode, so that the degradation of comfort can be suppressed even if the requested heating capacity is changed during the heat-storing and heating operation. Further, a sufficient amount of refrigerant with which the degradation of comfort can be suppressed can be supplied to the indoor heat exchanger 23 even if the requested heating capacity is increased during the heat-storing and heating operation, which eliminates the need to excessively increase the rotation speed of the compressor 21 and can suppress an increase in power consumption.
Although an embodiment of the present invention has been described above, the present invention is not limited only to the embodiment described above and it goes without saying that various modifications can be made thereto.
For example, although the refrigeration cycle device in which the single indoor unit 3 is connected to the outdoor unit 2 has been described as an example in the above embodiment, the present invention is not limited thereto and is also applicable to a refrigeration cycle device in which a plurality of indoor units 3 is connected to the outdoor unit 2.
Further, although the discharge pressure sensor 71 is used to detect the high pressure of the refrigerant in the above embodiment, instead of this, a sensor capable of detecting a pressure (condensation pressure) of the refrigerant flowing through the indoor heat exchanger 23 may be used, or a sensor capable of detecting a pressure of the refrigerant flowing through the auxiliary heat exchanger 53 may be used.

Reference Signs List

2: outdoor unit
3: indoor unit
20: refrigerant circuit
21: compressor
22: outdoor heat exchanger
23: indoor heat exchanger
24: main expansion valve
41: first four-way valve
42: second four-way valve
50: heat storage circuit
51: first bypass expansion valve
52: second bypass expansion valve
53: auxiliary heat exchanger
54: first bypass pipe (bypass flow path)
55: second bypass pipe (bypass flow path)
56: third bypass pipe (bypass flow path)
57: heat storage material
71: discharge pressure sensor (pressure sensor)
90: control device (controller)
100: refrigeration cycle device

Claims

A refrigeration cycle device, comprising:
a refrigerant circuit including
a compressor,

an outdoor heat exchanger,

an indoor heat exchanger, and

a main expansion valve disposed between the outdoor heat exchanger and the indoor heat exchanger;

a heat storage circuit including
a bypass flow path that connects a discharge side of the compressor to a refrigerant pipe located between the outdoor heat exchanger and the main expansion valve,

an auxiliary heat exchanger disposed in the bypass flow path and including a heat storage material capable of exchanging heat with part of a refrigerant discharged from the compressor,

a first bypass expansion valve disposed in the bypass flow path between the compressor and the auxiliary heat exchanger, and

a second bypass expansion valve disposed in the bypass flow path between the auxiliary heat exchanger and the refrigerant pipe;

a pressure sensor that detects a pressure of the refrigerant on the discharge side of the compressor; and

a controller that controls opening degrees of the main expansion valve, the first bypass expansion valve, and the second bypass expansion valve, wherein

the controller controls the opening degree of the first bypass expansion valve on a basis of a change rate of a detection value of the pressure sensor in a heat-storing and heating operation mode in which the indoor heat exchanger and the auxiliary heat exchanger are caused to function as condensers and the outdoor heat exchanger is caused to function as an evaporator.
The refrigeration cycle device according to claim 1, wherein
in the heat-storing and heating operation mode,

the controller
controls the opening degree of the first bypass expansion valve such that the opening degree of the first bypass expansion valve is reduced when the change rate of the detection value of the pressure sensor has a positive value, and

controls the opening degree of the first bypass expansion valve such that the opening degree of the first bypass expansion valve is increased when the change rate of the detection value of the pressure sensor has a negative value.
The refrigeration cycle device according to claim 1, wherein
the controller controls the opening degree of the first bypass expansion valve on a basis of the detection value of the pressure sensor when the heat-storing and heating operation mode starts.
The refrigeration cycle device according to any one of claims 1 to 3, wherein
in the heat-storing and heating operation mode, the controller controls the opening degree of the second bypass expansion valve such that a subcooling of the refrigerant that flows out of the auxiliary heat exchanger is a target subcooling set in advance.
The refrigeration cycle device according to any one of claims 1 to 3, wherein
the controller
calculates a theoretical discharge temperature that is a discharge temperature when the refrigerant suctioned into the compressor is assumed as a saturated steam, and

controls the opening degree of the main expansion valve such that a temperature of the refrigerant discharged from the compressor is the theoretical discharge temperature.