JP6545252B2 - Refrigeration cycle device - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus, and more particularly to liquid back suppression during defrosting operation.

An air conditioner etc. which cool or heat water using a refrigerating cycle device and use cold water or warm water obtained by this for air conditioning and the like are known. For example, an air-cooled heat pump chiller or the like corresponds to these refrigeration cycle devices.
When the refrigeration cycle apparatus is heated in low-temperature ambient air, that is, an air heat exchanger (outside heat exchanger) performing heat exchange between the ambient air and the refrigerant is used as an evaporator, and the water heat exchanger (chamber When the inner heat exchanger is used as a condenser (for example, when producing hot water used for heating), the air heat exchanger may be frosted. The frost that has arrived at the air heat exchanger impedes the heat exchange between the outside air and the refrigerant, and reduces the ability of the water heat exchanger to heat water. Therefore, it is necessary to quickly remove the frost that has reached the air heat exchanger (defrosting). As a system of defrosting, for example, a hot gas reverse system operating with an air heat exchanger as a condenser, an off-cycle defrost system stopping a refrigeration cycle apparatus, a heater defrost system heating by a heater installed near a heat exchanger Etc. In the air-cooled heat pump chiller, in particular, the defrosting operation is performed by the hot gas reverse method.

  In the air-cooled heat pump chiller, the refrigerant circuit is configured by connecting, for example, a compressor, an air heat exchanger, an expansion valve, a water heat exchanger, a refrigerant tank, and a four-way valve by a refrigerant pipe. An expansion valve between the air heat exchanger and the water heat exchanger is connected in series to the circuit. The refrigerant tank is disposed between the expansion valve and the water heat exchanger, and is connected in parallel to a refrigerant pipe that connects the expansion valve and the water exchanger. The four-way valve is connected so that the connection destination on the suction port side and the discharge port side of the compressor is connected so that the other connection destination is a water heat exchanger if one connection destination is an air heat exchanger It is connected so that the connection destination can be switched also to the opposite. In the refrigerant circuit, during heating operation, the four-way valve is switched so that the refrigerant circulates in the order of the compressor, the water heat exchanger, the expansion valve, and the air heat exchanger, and the water heat exchanger produces hot water. During cooling operation, the four-way valve is switched so that the refrigerant circulates in the order of the compressor, the air heat exchanger, the expansion valve, and the water heat exchanger, and the water heat exchanger produces cold water.

  In such a refrigerant circuit, since the air heat exchanger serving as the evaporator may be frosted during the heating operation, the hot gas reverse defrosting operation is performed. The hot gas reverse defrosting operation is a defrosting method in which a high temperature refrigerant gas (hot gas) discharged from the compressor is sent to a frosted air heat exchanger and the heat is used to melt the frost. At the start of defrosting, the liquid refrigerant accumulated in the refrigerant tank installed between the expansion valve and the water heat exchanger flows through the water heat exchanger to the compressor and enters the suction port of the compressor . That is, liquid back to the compressor occurs. Similarly, when the defrosting operation is finished and the heating operation is started, the liquid refrigerant accumulated in the air heat exchanger enters the suction port of the compressor. That is, liquid back to the compressor occurs. Therefore, in the prior art, in order to suppress liquid back, an accumulator was installed and it protected from liquid back to a compressor. However, the accumulator has a large capacity and requires a large space in the machine room. Therefore, in order to take measures against liquid back in a small space, a method of providing a refrigerant tank and adjusting the amount of refrigerant flowing in the refrigerant circuit by the flow rate adjustment device has been studied.

  In Patent Document 1, a refrigerant circuit in which a compressor, a condenser, a throttling device, and an evaporator are connected by a refrigerant pipe is configured, and a flow control device and a receiver that stores excess refrigerant in the refrigerant circuit are connected in series. A refrigerant circuit is disclosed in which the circuit is provided in parallel with the throttle device.

  In Patent Document 2, the compressor discharge unit and the low pressure after the solenoid valve are connected by a hot gas bypass, and the refrigerant circuit is divided into the low pressure unit and the high pressure unit to perform a defrosting operation, and an accumulator is provided on the suction side of the compressor. A refrigeration cycle device connected is disclosed.

  In Patent Document 3, when the pressure on the high-pressure side of the refrigerant circuit in operation rises by connecting the compressor suction portion and the rear of the solenoid valve and sandwiching the refrigerant tank between them, the refrigerant flows to the refrigerant tank Techniques for reducing the pressure on the high pressure side of the circuit are disclosed.

JP, 2014-119153, A Japanese Examined Patent Publication 7-52052 Unexamined-Japanese-Patent No. 5-288427

  The technology disclosed in Patent Document 1 constitutes a refrigerant circuit that adjusts the refrigerant flow rate according to the required refrigerant amount, and performs control to return the refrigerant accumulated in the receiver to the refrigerant circuit by opening the flow adjustment device at power failure Although it was intended, it did not aim at control at the time of defrosting operation.

  In the technology disclosed in Patent Document 2, a solenoid valve is connected to the compressor discharge side, and a hot gas bypass connecting the solenoid valve to the evaporator is provided, and installed at the downstream side of the condenser during the defrosting operation. The valve is closed and defrosting is performed by the circuit connecting the high pressure side of the compressor and the evaporator. In this configuration, the accumulator provided between the evaporator and the suction port of the compressor prevents liquid back to the compressor, and a space for installing the accumulator is required. In addition, a hot gas bypass is provided for defrosting. Therefore, there is a problem that the space in the machine room of the refrigeration cycle apparatus has to be taken large.

  In patent document 3, it is a refrigerant circuit which connects the suction port of a compressor, and an expansion valve, and sandwiches a refrigerant tank between, and when refrigerant circulation amount becomes excessive and high pressure pressure rises, it is a composition which stores refrigerant in a refrigerant tank It has become. In this configuration, control is performed to open the solenoid valve and store the refrigerant in the refrigerant tank when the pressure on the high pressure side of the refrigerant circuit is higher than specified, but this is not intended for defrosting, and during defrosting operation Was not configured to prevent liquid back to the compressor.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to enable liquid back suppression during defrosting operation of a refrigerant circuit in a refrigerant circuit provided with a refrigerant tank (high pressure receiver). It is said that.

The refrigeration cycle apparatus according to the present invention has a refrigerant circuit in which a compressor, a flow path switching valve, a heat source side heat exchanger, a main expansion valve, and a use side heat exchanger are connected by a refrigerant pipe, and is a hot gas In a refrigeration cycle apparatus that performs a defrosting operation by a reverse method, a pressure sensor that measures the pressure on the high pressure side in the refrigerant circuit, and a controller that controls the compressor, the flow path switching valve, and the main expansion valve , A refrigerant tank for storing surplus refrigerant, a sub expansion valve disposed on the heat source side heat exchanger side with respect to the refrigerant tank and capable of adjusting the opening degree, and the use side heat for the refrigerant tank A series circuit in which solenoid valves arranged on the exchanger side are connected in series is connected in parallel to the main expansion valve connected between the heat source side heat exchanger and the use side heat exchanger, the control Location, based on the pressure measurement of the pressure sensor, until said control opening and closing of the sub-expansion valve opening degree and the solenoid valve, the pressure after the start of the defrosting operation is reach the specified value, the When the sub expansion valve is fully open and the solenoid valve is closed and the pressure is higher than a specified value, the sub expansion valve is fully closed and the solenoid valve is opened, and the pressure is higher than the specified value. When it is low, the sub expansion valve is opened and the solenoid valve is closed .

  According to the present invention, by controlling the sub expansion valve and the solenoid valve at the start of the defrosting operation, the amount of refrigerant in the refrigerant tank is adjusted, and the amount of refrigerant necessary for the defrosting operation is output to the refrigerant circuit. The liquid back to the compressor generated at the time of the defrosting operation can be suppressed.

5 is a schematic view of a refrigerant circuit of the refrigeration cycle apparatus in Embodiment 1. FIG. It is a schematic diagram of the refrigerant circuit of the refrigerating cycle device of prior art (comparative example). FIG. 5 is a diagram showing a control flow of the refrigeration cycle device in the first embodiment. It is an explanatory view showing a relation of high pressure side pressure to time progress at the time of defrosting operation of a refrigerant circuit, and movement of an electromagnetic valve accompanying it. FIG. 8 is a diagram showing a control flow of the refrigeration cycle device in the second embodiment.

Embodiment 1
Hereinafter, a refrigeration cycle apparatus 1 according to the present embodiment will be described using the drawings.
FIG. 1 is a schematic view of a refrigerant circuit 2 of a refrigeration cycle apparatus 1 in the present embodiment. The refrigeration cycle apparatus 1 according to the present embodiment is, for example, an air conditioner that uses cold water or hot water obtained by cooling or heating water for cooling and heating. For example, an air-cooling heat pump chiller or the like corresponds to the refrigeration cycle apparatus 1.

  The refrigerant circuit 2 of the refrigeration cycle apparatus 1 includes a compressor 21, an air heat exchanger 22 (corresponding to a heat source side heat exchanger of the present invention), a main expansion valve 24, a water heat exchanger 25 (a utilization side heat of the present invention The sub expansion valve 26, the refrigerant tank 27, the solenoid valve 28, and the four-way valve 29 (corresponding to the flow path switching valve of the present invention) are connected by a refrigerant pipe. The sub expansion valve 26, the refrigerant tank 27, and the solenoid valve 28 are connected in series in the refrigerant circuit. The sub expansion valve 26, the refrigerant tank 27, and the solenoid valve 28 connected in parallel are connected to the main expansion valve 24 located between the air heat exchanger 22 and the water heat exchanger 25.

  In the case where one connection destination is the air heat exchanger 22 and the other connection destination is the water heat exchanger 25, the four-way valve 29 connects the suction port side and the discharge port side of the compressor 21 respectively. , And vice versa are connected. In addition, switching of the connection destination is not limited to the four-way valve 29, and switching the connection destinations on the suction port side and the discharge port side of the compressor 21 may reverse the circulation direction of the refrigerant in the refrigerant circuit 2 and other flow paths. A switching valve may be used. The main expansion valve 24 works as a pressure reducing device in the refrigerant circuit 2. The sub expansion valve 26 can change the degree of opening to the state of full opening, full closing, or throttling, and can pass the refrigerant without depressurizing the refrigerant at full opening or with little pressure reduction, and shut off the flow of refrigerant at full closing. be able to. When the sub expansion valve 26 is in the throttled state, it works as a pressure reducing device in the refrigerant circuit 2 in the same manner as the main expansion valve 24. The solenoid valve 28 can perform open / close control. When open, the refrigerant can be passed without pressure reduction or with little pressure reduction, and when closed, the flow of refrigerant can be shut off.

  The refrigeration cycle apparatus 1 is provided with a pressure sensor 3, and measures the pressure on the high pressure side of the refrigerant circuit 2. Further, the refrigeration cycle apparatus 1 is provided with a control device 4. The control device 4 controls the operation of the compressor 21, the four-way valve 29, and the main expansion valve 24, and performs opening / closing control of the sub expansion valve 26 and the solenoid valve 28 based on the measurement value of the pressure sensor 3. The control device 4 is configured of, for example, a microcomputer. The relationship between the pressure on the high pressure side of the refrigerant circuit 2 and the opening degree control of the sub expansion valve 26 and the opening / closing control of the solenoid valve 28 will be described later.

  A fan 23 is attached to the air heat exchanger 22, and the fan 23 sends air (outside air) outside the refrigeration cycle apparatus 1 to the air heat exchanger 22 to exchange heat between the refrigerant and the outside air. It is. If frost is formed on the air heat exchanger 22 during the heating operation, the air that the fan 23 sends to the air heat exchanger 22 becomes difficult to pass, and the heat exchange efficiency decreases.

(Motion of refrigeration cycle device 1 during heating operation)
The flow of the refrigerant in the refrigerant circuit 2 of the refrigeration cycle apparatus 1 and the function of each element in the refrigerant circuit in the heating operation (when hot water is produced by the water heat exchanger 25) will be described.
The refrigerant flowing into the piping of the refrigerant circuit 2 is compressed by the compressor 21 to be brought to a high temperature and a high pressure, and enters the four-way valve 29. During the heating operation, the four-way valve 29 is switched as shown by the dotted line in FIG. 1, and the high-temperature and high-pressure refrigerant discharged from the discharge port of the compressor 21 flows into the water heat exchanger 25. The water heat exchanger 25 serves as a condenser during heating operation, and heat exchange is performed between water and a refrigerant. The high-temperature and high-pressure refrigerant releases heat to water in the water heat exchanger 25, condenses and becomes a liquid refrigerant.
The liquid refrigerant that has flowed out of the water heat exchanger 25 is depressurized through the main expansion valve 24 and turned into a low temperature low pressure gas-liquid two-phase refrigerant. During the heating operation, the solenoid valve 28 is normally open, and the refrigerant that has left the water heat exchanger 25 also flows to the refrigerant tank 27. The refrigerant tank has a function to store surplus refrigerant during heating operation. Further, the sub expansion valve 26 connected to the refrigerant tank 27 is in a throttled state, and works as a refrigerant pressure reducing device.

  The refrigerant in the gas-liquid two-phase state by the main expansion valve 24 and the sub expansion valve 26 flows into the air heat exchanger 22. The air heat exchanger 22 becomes an evaporator during heating operation, and heat exchange is performed between the outside air and the refrigerant. The low temperature low pressure gas-liquid two-phase refrigerant receives heat from the outside air in the air heat exchanger 22 and becomes a superheated gas. The refrigerant which has become the superheated gas flows into the suction port of the compressor 21 through the four-way valve 29. After that, it circulates the same route again.

(Motion of refrigeration cycle device 1 during defrosting operation)
The flow of the refrigerant in the refrigerant circuit 2 of the refrigeration cycle apparatus 1 during the defrosting operation and the functions of the respective elements in the refrigerant circuit will be described.
When the refrigeration cycle apparatus 1 is operated for heating in low-temperature outside air, that is, when the air heat exchanger 22 performing heat exchange between the outside air and the refrigerant is used as an evaporator and the water heat exchanger 25 is used as a condenser The air heat exchanger 22 may be frosted (for example, when producing hot water used for heating). If frost is formed on the air heat exchanger 22, heat exchange between the outside air and the refrigerant in the air heat exchanger 22 is inhibited, and the ability of the water heat exchanger 25 side to heat water is reduced. The frost operation removes the frost that has arrived at the air heat exchanger 22.

  In the refrigeration cycle apparatus 1 of the present embodiment, defrosting is performed by the hot gas reverse method. When the defrosting operation is started, the four-way valve 29 is switched as shown by the solid line in FIG. The high-temperature, high-pressure gas refrigerant that has exited from the discharge port of the compressor 21 flows into the frosted air heat exchanger 22. As a result, the frost that has reached the air heat exchanger 22 melts and is defrosted.

(Refrigerating cycle device in comparative example)
FIG. 2 is a schematic view of the refrigerant circuit 102 of the refrigeration cycle apparatus 101 of the prior art (comparative example). The refrigerant circuit 102 of the refrigeration cycle apparatus 101 is configured by connecting a compressor 11, an air heat exchanger 12, a main expansion valve 14, a water heat exchanger 15, a refrigerant tank 17, and a four-way valve 19 by refrigerant piping. The refrigerant tank 17 is connected in parallel to the main expansion valve 14 located between the air heat exchanger 12 and the water heat exchanger 15. In the case where one connection destination is the air heat exchanger 12 and the other connection destination is the water heat exchanger 15, the four-way valve 19 is connected to the suction port side and the discharge port side of the compressor 11, respectively. , And vice versa are connected. A fan 13 is attached to the air heat exchanger 12, and the fan 13 sends air (outside air) outside the refrigeration cycle apparatus 101 to the air heat exchanger 12 to exchange heat between the refrigerant and the outside air. It is.

Generally, in the refrigerant circuit 102 such as the refrigeration cycle apparatus 101, the internal volume of the air heat exchanger is larger than that of the water heat exchanger. During the heating operation, since the air heat exchanger 12 with a relatively small internal volume serves as a condenser, the amount of refrigerant required is smaller than in the cooling operation, and surplus refrigerant is generated. Therefore, during the heating operation, the refrigerant is accumulated in the refrigerant tank 17. The same applies to the refrigeration cycle apparatus 1 of the present embodiment.
During the defrosting operation, the refrigerant stored in the refrigerant tank 17 is connected to connect the discharge side of the compressor 11 to the air heat exchanger 12 and the suction side to the water heat exchanger 15 and reverse the circulation of the refrigerant with respect to the heating operation. All flow out on the main refrigerant circuit. However, when all the surplus refrigerant is made to flow out of the refrigerant tank 17, the refrigerant is large relative to the amount of refrigerant required at the time of the defrosting operation, and the liquid refrigerant accumulated in the refrigerant tank 17 passes through the water heat exchanger 15. It will flow to the suction side and a liquid back will occur. Therefore, in the refrigeration cycle apparatus 101 of the comparative example, some measure against liquid back is required.

(Control of the refrigeration cycle apparatus 1 in the first embodiment)
FIG. 3 is a diagram of a control flow of the refrigeration cycle apparatus 1 in the present embodiment.
In the refrigeration cycle apparatus 101 of the comparative example, a countermeasure for liquid back is necessary, so in the present embodiment, the refrigerant circuit 2 such as the refrigeration cycle apparatus 1 is configured, and liquid back is prevented by control described below. ing.

  When the defrosting operation is started, the control device 4 installed in the refrigeration cycle device 1 controls the pressure on the high pressure side in the refrigerant circuit 2 (for example, the refrigerant pipe from the discharge port of the compressor 21 to the four-way valve 29 The pressure of the high pressure side of the refrigerant circuit 2 is detected based on the value from the pressure sensor 3 which is measuring the pressure), and the judgment high pressure (corresponding to the specified value of the present invention) or higher is judged It is determined whether it is lower (control step S1). If the high pressure side pressure is lower than the judgment high pressure, the control device 4 closes the solenoid valve 28 (control step S2), fully opens the sub expansion valve 26 (control step S3), and the main circuit 5 Take out inside. The main circuit 5 is a portion of a circuit in which the compressor 21, the four-way valve 29, the air heat exchanger 22, the main expansion valve 24, and the water heat exchanger 25 are connected by refrigerant piping and the refrigerant circulates. By discharging the refrigerant in the refrigerant tank 27 to the main circuit 5, the shortage of the amount of refrigerant in the main circuit 5 is eliminated, and an effect such as the problem of the overheating operation of the compressor 21 can be avoided.

  If the high-pressure side pressure is higher than the determination high pressure, the control device 4 opens the solenoid valve 28 (control step S4) and fully closes the sub expansion valve 26 (control step S5). 28 into the refrigerant tank 27 from the side. As a result, the amount of refrigerant necessary for defrosting can be output to the main circuit 5, and an effect such as liquid back to the compressor 21 caused by the presence of excess refrigerant in the main circuit 5 can be avoided.

  After the control step S2-S3 or the control step S4-S5 is performed, the control device 4 determines whether the defrosting operation end condition is satisfied (control step S6). If the defrosting operation end condition is not satisfied, the process returns to the control step S1 again. When the defrosting operation end condition is satisfied, the control at the time of the defrosting operation is ended. The defrosting operation end condition is, for example, when the temperature of the air heat exchanger 22 becomes higher than a specified value, or when the elapsed time from the start of the defrosting operation becomes higher than the specified value, or when both of them are satisfied. It is judged by the condition of.

FIG. 4 is an explanatory view showing the relationship between the high-pressure side pressure and the movement of the solenoid valve 28 associated with the passage of time during the defrosting operation of the refrigerant circuit 2.
The pressure in FIG. 4 is the pressure on the high pressure side in the refrigerant circuit 2. Specifically, the pressure of the refrigerant between the compressor 21 and the four-way valve 29 which is on the discharge side of the compressor 21 is measured. When the refrigeration cycle apparatus 1 switches to the defrosting operation, the pressure in the refrigerant circuit 2 increases with time. If the rate of increase of the pressure in the refrigerant circuit 2 with respect to the passage of time is larger than the specified (that is, the slope of the straight line in FIG. 4 is larger than the specified), the controller 4 determines that the high pressure is present. If the rate of increase of the pressure in the refrigerant circuit 2 with respect to the passage of time is smaller than the specified (that is, the slope of the straight line in FIG. 4 is smaller than the specified), the controller 4 determines that the pressure is low. The control device 4 controls the opening and closing of the sub expansion valve 26 and the solenoid valve 28 as described above according to this determination.

  When the high pressure side pressure is lower than the determination high pressure, the control device 4 can close the solenoid valve 28 and control the sub expansion valve 26 in a throttled state. In the case of control in which the sub expansion valve 26 is fully opened, the pressure in the main circuit 5 may immediately become high, and when the high pressure side pressure becomes higher than the determination high pressure, the sub expansion valve 26 is fully closed again. It controls to open. Then, it is necessary to frequently perform the opening and closing control of the sub expansion valve 26 and the solenoid valve 28, and the operation is not stable. However, by throttling the degree of opening of the sub expansion valve 26, the amount of outflow from the refrigerant tank 27 to the main circuit 5 can be controlled, and the pressure fluctuation of the main circuit 5 can be moderated. Thereby, the frequency of opening and closing of the sub expansion valve 26 and the solenoid valve 28 can be reduced, and the defrosting operation of the refrigeration cycle apparatus 1 can be stably performed.

Second Embodiment
In the present embodiment, control steps of the sub expansion valve 26 and the solenoid valve 28 are added after the start of the defrosting operation and before the end of the defrosting operation in addition to the refrigerant circuit 2 and the control thereof in the first embodiment. . Here, a description will be made focusing on the points that are different from the first embodiment.
FIG. 5 is a diagram of a control flow of the refrigeration cycle apparatus 1 in the present embodiment.
The refrigeration cycle apparatus 1 according to the present embodiment performs a heating operation in a state where the sub expansion valve 26 is squeezed and the solenoid valve 28 is opened. At the start of the defrosting operation, the refrigeration cycle apparatus 1 switches the four-way valve 29 to change the circulation direction of the refrigerant. Thereafter, the control device 4 fully opens the sub expansion valve 26 and closes the solenoid valve 28 (control step S0). Thereafter, the process proceeds to control step S1, and the control device 4 detects a change with time of the pressure on the high pressure side of the refrigerant circuit 2, and determines whether it is a determination high pressure (corresponding to a specified value in the present invention) or lower judge. That is, the same control steps S1-S6 as in the first embodiment are performed.

Immediately after the start of the defrosting operation, that is, at the control step S0, the pressure stored in the refrigerant tank 27 flows out to the main circuit 5 through the sub expansion valve 26 because the pressure on the high pressure side of the refrigerant circuit 2 is low. When a sufficient amount of refrigerant flows out to the main circuit 5, the pressure on the high pressure side of the refrigerant circuit 2 rises. If the rate of increase of the pressure in the refrigerant circuit 2 with respect to the passage of time becomes larger than a predetermined value (that is, the slope of the straight line in FIG. 4 becomes larger than a predetermined value) due to the pressure increase, the control device 4 The valve 28 is opened and the sub expansion valve 26 is closed. That is, control of control step S4-S5 is performed through control step S1. In this case, the refrigerant in the refrigerant circuit 2 flows into the refrigerant tank 27 via the solenoid valve 28. As a result, the amount of refrigerant in the refrigerant circuit 2 that has reached a high pressure decreases, and the pressure in the refrigerant circuit 2 decreases.
If the pressure on the high pressure side of the refrigerant circuit 2 is lower than the specified value even if the refrigerant flows out to the main circuit 5, the control device 4 opens the sub expansion valve 26 and closes the solenoid valve 28.

When control step S6 is reached by the same control as in the first embodiment, control device 4 determines whether the defrosting operation end condition is satisfied. If the defrosting operation end condition is not satisfied, the process returns to the control step S1 again. When the defrosting operation end condition is satisfied, the control device 4 performs control of fully opening the sub expansion valve 26 and closing the solenoid valve 28 (control step S7). Thereafter, the four-way valve 29 is switched, and the heating operation is resumed. In the heating operation, the air heat exchanger 22 side of the refrigerant circuit 2 is on the low pressure side, but immediately after the heating operation is started, liquid refrigerant is present in the air heat exchanger 22 in the defrosting operation. However, since the refrigerant in the main circuit 5 flows into the refrigerant tank 27 by fully opening the sub expansion valve 26 and closing the solenoid valve 28, the liquid refrigerant present in the air heat exchanger 22 goes to the compressor 21. Will disappear.
In addition, what is necessary is just to set predetermined | prescribed time before the defrost operation completion (before heating operation resumption) according to the specification of the refrigerating cycle apparatus 1, for example as the timing transfered to control step S7. In this case, the control step S7 ends when a predetermined time has elapsed, and the defrost control ends. Thereafter, the heating operation is resumed. Further, for example, a pressure change in the refrigerant circuit 2 is detected, and when the pressure satisfies a predetermined condition, the process proceeds to control step S7, and when the pressure decreases to a specified value, the control step S7 is ended and defrosting is performed. Control ends.

  By performing the above control, the amount of refrigerant in the main circuit 5 is properly maintained, and the pressure is also maintained at an appropriate value. Accordingly, it is possible to suppress the occurrence of liquid back to the compressor 21 when switching from the heating operation to the defrosting operation and when switching from the defrosting operation to the heating operation.

  Reference Signs List 1 refrigeration cycle device, 2 refrigerant circuit, 3 pressure sensor, 4 control device, 5 main circuit, 11 compressor, 12 air heat exchanger, 13 fan, 14 main expansion valve, 15 water heat exchanger, 17 refrigerant tank, 18 Solenoid valve, 19 four-way valve, 21 compressor, 22 air heat exchanger, 23 fan, 24 main expansion valve, 25 water heat exchanger, 26 sub expansion valve, 27 refrigerant tank, 28 solenoid valve, 29 four-way valve, 101 refrigeration Cycle device, 102 refrigerant circuit.

Claims (7)

A refrigeration circuit having a refrigerant circuit in which a compressor, a flow path switching valve, a heat source side heat exchanger, a main expansion valve, and a use side heat exchanger are connected by refrigerant piping, and performing a defrosting operation by a hot gas reverse method In the cycle device
A pressure sensor that measures the pressure on the high pressure side in the refrigerant circuit;
A control device that controls the compressor, the flow path switching valve, and the main expansion valve, respectively;
A refrigerant tank for storing excess refrigerant, a sub expansion valve arranged on the heat source side heat exchanger side with respect to the refrigerant tank and capable of adjusting the opening degree, and a refrigerant side for the refrigerant tank on the use side heat exchanger side A series circuit in which arranged solenoid valves are connected in series is connected in parallel to the main expansion valve connected between the heat source side heat exchanger and the use side heat exchanger;
The controller is
The opening degree of the sub expansion valve and the opening and closing of the solenoid valve are controlled based on the pressure measured by the pressure sensor ,
After the start of the defrosting operation and until the pressure reaches a specified value, the sub expansion valve is fully opened and the solenoid valve is closed,
When the pressure is higher than a specified value, the sub expansion valve is fully closed and the solenoid valve is opened, and when the pressure is lower than the specified value, the sub expansion valve is opened and the solenoid valve is Close, refrigeration cycle equipment. A refrigeration circuit having a refrigerant circuit in which a compressor, a flow path switching valve, a heat source side heat exchanger, a main expansion valve, and a use side heat exchanger are connected by refrigerant piping, and performing a defrosting operation by a hot gas reverse method In the cycle device
A pressure sensor that measures the pressure on the high pressure side in the refrigerant circuit;
A control device that controls the compressor, the flow path switching valve, and the main expansion valve, respectively;
A refrigerant tank for storing excess refrigerant, a sub expansion valve arranged on the heat source side heat exchanger side with respect to the refrigerant tank and capable of adjusting the opening degree, and a refrigerant side for the refrigerant tank on the use side heat exchanger side A series circuit in which arranged solenoid valves are connected in series is connected in parallel to the main expansion valve connected between the heat source side heat exchanger and the use side heat exchanger;
The controller is
The opening degree of the sub expansion valve and the opening and closing of the solenoid valve are controlled based on the pressure measured by the pressure sensor ,
When the pressure is higher than a specified value, the sub expansion valve is fully closed and the solenoid valve is opened, and when the pressure is lower than the specified value, the degree of opening of the sub expansion valve is narrowed, and A refrigeration cycle device that closes a solenoid valve . A refrigeration circuit having a refrigerant circuit in which a compressor, a flow path switching valve, a heat source side heat exchanger, a main expansion valve, and a use side heat exchanger are connected by refrigerant piping, and performing a defrosting operation by a hot gas reverse method In the cycle device
A pressure sensor that measures the pressure on the high pressure side in the refrigerant circuit;
A control device that controls the compressor, the flow path switching valve, and the main expansion valve, respectively;
A refrigerant tank for storing excess refrigerant, a sub expansion valve arranged on the heat source side heat exchanger side with respect to the refrigerant tank and capable of adjusting the opening degree, and a refrigerant side for the refrigerant tank on the use side heat exchanger side A series circuit in which arranged solenoid valves are connected in series is connected in parallel to the main expansion valve connected between the heat source side heat exchanger and the use side heat exchanger;
The controller is
The opening degree of the sub expansion valve and the opening and closing of the solenoid valve are controlled based on the pressure measured by the pressure sensor ,
A refrigeration cycle apparatus , wherein the sub expansion valve is fully opened and the solenoid valve is closed after the start of the defrosting operation until the pressure reaches a specified value . A refrigeration circuit having a refrigerant circuit in which a compressor, a flow path switching valve, a heat source side heat exchanger, a main expansion valve, and a use side heat exchanger are connected by refrigerant piping, and performing a defrosting operation by a hot gas reverse method In the cycle device
A pressure sensor that measures the pressure on the high pressure side in the refrigerant circuit;
A control device that controls the compressor, the flow path switching valve, and the main expansion valve, respectively;
A refrigerant tank for storing excess refrigerant, a sub expansion valve arranged on the heat source side heat exchanger side with respect to the refrigerant tank and capable of adjusting the opening degree, and a refrigerant side for the refrigerant tank on the use side heat exchanger side A series circuit in which arranged solenoid valves are connected in series is connected in parallel to the main expansion valve connected between the heat source side heat exchanger and the use side heat exchanger;
The controller is
The opening degree of the sub expansion valve and the opening and closing of the solenoid valve are controlled based on the pressure measured by the pressure sensor ,
A refrigeration cycle apparatus , wherein the sub expansion valve is fully opened and the solenoid valve is closed for a predetermined time before the end of the defrosting operation . The refrigeration cycle apparatus according to claim 2 , wherein the sub expansion valve is fully opened and the solenoid valve is closed after the start of the defrosting operation until the pressure reaches a specified value. The refrigeration cycle apparatus according to claim 2 or 3 , wherein the sub expansion valve is fully opened and the solenoid valve is closed for a predetermined time before the end of the defrosting operation. The controller is
If the rate of increase in pressure measured by the pressure sensor with respect to the passage of time is greater than specified, it is determined that the pressure is higher than a specified value, and if the rate of increase in pressure is smaller than specified, the pressure is defined. The refrigeration cycle apparatus according to any one of claims 1 to 6, which is determined to be lower than the value .

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