JP7331021B2 - refrigeration cycle equipment - Google Patents

Description

The present disclosure relates to a refrigeration cycle device.

Conventionally, a refrigeration cycle apparatus is known that performs a defrost operation to remove frost generated in an evaporator using high-temperature, high-pressure gas refrigerant discharged from a compressor. For example, Japanese Patent No. 6403907 (Patent Document 1) describes a hot gas bypass pipe that directly connects from the discharge side of the compressor to the evaporator, and a flow control valve that adjusts the flow rate of the refrigerant flowing through the hot gas bypass pipe. A refrigeration cycle apparatus is disclosed. The refrigeration cycle device disclosed in Patent Document 1 adjusts the flow rate of refrigerant flowing through the hot gas bypass pipe according to the degree of discharge superheat of the refrigerant discharged from the compressor and the suction pressure of the compressor.

Japanese Patent No. 6403907

In the refrigeration cycle apparatus described in Patent Document 1, the flow rate of refrigerant from the compressor to the evaporator is adjusted during the defrost operation in order to suppress the occurrence of failure of the compressor due to liquid return. However, since the refrigerant is depressurized when passing through the flow control valve, the temperature of the refrigerant flowing into the evaporator drops. Therefore, the time required for the defrost operation becomes longer.

An object of the present disclosure is to provide a refrigeration cycle apparatus capable of suppressing the occurrence of compressor failure and shortening the time required for defrost operation.

A refrigeration cycle apparatus of the present disclosure includes a refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are connected by piping. The refrigeration cycle device further includes a switching circuit, a detector, a pressure regulator, and a controller. The switching circuit switches between a cooling operation in which refrigerant is circulated in the order of the compressor, condenser, expansion valve and evaporator, and a defrost operation in which refrigerant discharged from the compressor flows into the evaporator. The detector detects the pressure and degree of superheat of the refrigerant sucked into the compressor. A pressure regulator regulates the pressure of the refrigerant sucked into the compressor. The controller controls the pressure regulator during the defrost operation so that the pressure and degree of superheat detected by the detector fall within specified ranges.

According to the present disclosure, the high-temperature and high-pressure refrigerant discharged from the compressor 11 can flow into the evaporator, the amount of heat for melting frost attached to the evaporator can be increased, and the time required for defrost operation can be shortened. Furthermore, since the pressure regulator is controlled so that the pressure and the degree of superheat detected by the detector fall within a specified range, the occurrence of compressor failure can be suppressed.

1 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 1; FIG. 4 is a flow chart showing the flow of control during defrost operation in the refrigeration cycle apparatus according to Embodiment 1. FIG. It is a schematic block diagram of the refrigerating-cycle apparatus which concerns on a reference form. FIG. 2 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 2; FIG. 10 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 3; 10 is a flow chart showing the flow of control during defrost operation in the refrigeration cycle apparatus according to Embodiment 3. FIG. FIG. 11 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 4; 14 is a flow chart showing the flow of control during defrost operation in the refrigeration cycle apparatus according to Embodiment 4. FIG. FIG. 10 is a diagram showing a schematic configuration of a refrigeration cycle apparatus according to Embodiment 5 and a flow of refrigerant during cooling operation; FIG. 10 is a diagram showing a schematic configuration of a refrigeration cycle apparatus according to Embodiment 5 and a flow of refrigerant during defrost operation; 14 is a flow chart showing the flow of control during defrost operation in the refrigeration cycle apparatus according to Embodiment 5. FIG. FIG. 11 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 6; FIG. 11 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 7;

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. A plurality of embodiments will be described below, but appropriate combinations of the configurations described in the respective embodiments have been planned since the filing of the application. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated. Furthermore, the forms of the components shown in the entire specification are merely examples, and are not limited to these descriptions.

Embodiment 1.
(Configuration of refrigeration cycle device)
FIG. 1 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 1. FIG. A refrigerating cycle device 1 shown in FIG. 1 performs a cooling operation using a refrigerating cycle that circulates a refrigerant. Referring to FIG. 1 , refrigeration cycle apparatus 1 includes refrigerant circuit 10 , switching circuit 20 , pressure sensor 41 , temperature sensors 42 and 43 , pressure regulator 44 and controller 50 .

The refrigerant circuit 10 is a circuit in which a compressor 11, a condenser 12, an expansion valve 13 and an evaporator 14 are connected by piping. A refrigerant circulates in the refrigerant circuit 10 . When the compressor 11 is driven, the refrigerant passes through the compressor 11 , the condenser 12 , the expansion valve 13 and the evaporator 14 in order and returns to the compressor 11 .

The compressor 11 sucks the refrigerant and compresses the sucked refrigerant into a high-temperature and high-pressure state. The compressor 11 is, for example, an inverter compressor, and is configured to have a variable capacity according to the number of revolutions controlled by the inverter. The compressor 11 is filled with refrigerating machine oil for lubricating internal parts.

The refrigerant circuit 10 may include an oil separator on the discharge side of the compressor 11 . The oil separator separates the refrigerating machine oil component from the refrigerant gas in which the refrigerating machine oil is mixed in the refrigerant discharged from the compressor 11 . Refrigerating machine oil separated in the oil separator is returned to the compressor 11 through a capillary tube connected to the compressor 11 .

The condenser 12 exchanges heat between air supplied from, for example, a condenser fan 16 and the refrigerant. The condenser 12 is connected to the discharge side of the compressor 11 and condenses the refrigerant discharged from the compressor 11 . The refrigerant condensed by condenser 12 is sent to expansion valve 13 .

The expansion valve 13 expands the refrigerant condensed by the condenser 12 to reduce the pressure. The refrigerant decompressed by the expansion valve 13 is sent to the evaporator 14 .

The evaporator 14 exchanges heat between the air and the refrigerant, and evaporates the refrigerant depressurized by the expansion valve 13 . Air is supplied to the evaporator 14 from a blower fan 17 to promote heat exchange. The refrigerant evaporated and gasified by the evaporator 14 is sucked into the compressor 11 .

Refrigerant circuit 10 further includes an accumulator 15 arranged between evaporator 14 and compressor 11 . The accumulator 15 stores the refrigerant that has passed through the evaporator 14 and is connected to the suction side of the compressor 11 . Refrigerant stored in the accumulator 15 is sucked into the compressor 11 and compressed. An oil return pipe (not shown) is connected to the bottom side of the accumulator 15, and oil and a small amount of liquid refrigerant are returned to the compressor 11 from the oil return pipe.

The switching circuit 20 is a circuit for switching between cooling operation and defrosting operation. The cooling operation is an operation in which the refrigerant is circulated in the order of the compressor 11, the condenser 12, the expansion valve 13, and the evaporator 14. The defrosting operation is an operation in which the refrigerant discharged from the compressor 11 flows into the evaporator 14. be. The switching circuit 20 includes a hot gas bypass pipe 21 and a hot gas solenoid valve (hereinafter referred to as “H/G solenoid valve”) 22 .

A hot gas bypass pipe 21 connects the discharge side of the compressor 11 and the evaporator 14 . Specifically, the hot gas bypass pipe 21 includes a branch point 60 between the compressor 11 and the condenser 12 in the refrigerant circuit 10 and a branch point 61 between the expansion valve 13 and the evaporator 14 in the refrigerant circuit 10. to connect. The H/G solenoid valve 22 is arranged on the hot gas bypass pipe 21 .

The pressure sensor 41 is arranged on the suction side of the compressor 11 and operates as a detection unit that detects the pressure of the refrigerant sucked into the compressor 11 (hereinafter referred to as “suction pressure Pin”). The temperature sensor 42 is arranged on the suction side of the compressor 11 in the refrigerant circuit 10 and detects the temperature of the refrigerant sucked into the compressor 11 . The temperature sensor 43 is arranged on the outlet side of the evaporator 14 in the refrigerant circuit 10 and detects the temperature of the refrigerant that has passed through the evaporator 14 .

The pressure regulator 44 is arranged on the suction side of the compressor 11 , for example, between the evaporator 14 and the accumulator 15 , and regulates the pressure of the refrigerant sucked into the compressor 11 . The pressure regulator 44 is composed of a component whose pressure can be adjusted. For example, the pressure regulator 44 is configured by an electronic expansion valve, a pressure regulation valve, a temperature expansion valve, or the like. An example in which the pressure regulator 44 is an electronic expansion valve will be described below.

The controller 50 is composed of, for example, a microcomputer board, and controls the opening and closing of the H/G electromagnetic valve 22 and the pressure adjustment amount of the pressure regulator 44 . In cooling operation, the controller 50 controls the H/G solenoid valve 22 to the closed state and controls the pressure adjustment amount of the pressure regulator 44 to a constant amount. For example, the controller 50 controls the degree of opening of the electronic expansion valve that constitutes the pressure regulator 44 to the maximum during cooling operation.

During the defrost operation, the controller 50 controls the H/G solenoid valve 22 to be in an open state, and adjusts the pressure adjustment amount of the pressure regulator 44 so that the suction pressure Pin detected by the pressure sensor 41 falls within the first specified range. to control. The first prescribed range is determined in advance from the operating range of compressor 11 in which the occurrence of failures can be suppressed. Specifically, the controller 50 controls the degree of opening of the electronic expansion valve that constitutes the pressure regulator 44 so that the suction pressure Pin is equal to or lower than a predetermined upper limit value Pref. The upper limit value Pref indicates the upper limit of the first prescribed range.

Furthermore, the controller 50 uses the suction pressure Pin detected by the pressure sensor 41 and the temperature detected by the temperature sensor 42 to determine the degree of superheat of the refrigerant sucked into the compressor 11 (hereinafter referred to as “suction superheat SH”). ) is calculated. That is, the controller 50, the pressure sensor 41, and the temperature sensor 42 operate as a detector that detects the suction superheat SH. In the defrost operation, the controller 50 controls the pressure adjustment amount of the pressure regulator 44 so that the suction superheat SH is within the second specified range. The second specified range is determined in advance from the operating range of compressor 11 in which occurrence of failure can be suppressed. Specifically, the controller 50 controls the degree of opening of the electronic expansion valve that constitutes the pressure regulator 44 so that the suction superheat SH becomes equal to or greater than a predetermined target value SHref. The target value SHref indicates the lower limit of the second specified range in which occurrence of failure of the compressor 11 can be suppressed.

(Control of defrost operation)
FIG. 2 is a flow chart showing the flow of control during defrost operation in the refrigeration cycle apparatus according to Embodiment 1. FIG. The defrost operation control shown in FIG. 2 is executed when it is determined that the defrost operation is necessary, or when the defrost operation is performed regularly. Before the defrost operation control shown in FIG. 2, cooling operation end processing, pump-down operation, unit stop processing, and processing for closing the suction side damper of the evaporator 14 are executed. The pump-down operation closes the expansion valve 13 and confines the refrigerant remaining in the refrigerant circuit 10 upstream of the expansion valve 13 . Rotation of the condenser fan 16 and the blower fan 17 is stopped by the unit stop processing. By closing the suction-side damper of the evaporator 14, the inflow of air to the evaporator 14 is blocked.

First, in step S1, the controller 50 switches the H/G solenoid valve 22 from the closed state to the open state. As a result, the high-temperature, high-pressure refrigerant discharged from the compressor 11 flows into the evaporator 14 through the hot gas bypass pipe 21 . As a result, frost adhering to the inside of the evaporator 14 can be melted in a short period of time.

In step S<b>2 , the controller 50 acquires the suction pressure Pin and the suction superheat SH of the refrigerant on the suction side of the compressor 11 . That is, the controller 50 acquires the detection value of the pressure sensor 41 as the suction pressure Pin. Further, the controller 50 calculates the suction superheat SH based on the detected value of the pressure sensor 41 and the detected value of the temperature sensor 42 .

In step S3, the controller 50 determines whether or not the suction pressure Pin exceeds the upper limit value Pref for a specified time t1. The controller 50 stores in advance the upper limit value Pref and the specified time t1. The prescribed time t1 is, for example, 3 seconds.

If the suction pressure Pin exceeds the upper limit value Pref for the specified time t1, that is, if YES in step S3, in step S4, the controller 50 sets the opening of the electronic solenoid valve that constitutes the pressure regulator 44 to 1 Decrease by one step. As a result, the pressure on the suction side of the compressor 11 is reduced, and the occurrence of failure of the compressor 11 can be suppressed.

If the suction pressure Pin has not exceeded the upper limit value Pref for the specified time t1, that is, if NO in step S3, in step S5, the controller 50 specifies the time during which the suction superheat SH is less than the target value SHref. It is determined whether or not the time t2 has continued. The controller 50 stores in advance the target value SHref and the specified time t2. The specified time t2 is, for example, 3 seconds.

If the time during which the suction superheat SH is less than the target value SHref continues for the specified time t2, that is, if YES in step S5, in step S6, the controller 50 controls the opening degree of the electronic solenoid valve that constitutes the pressure regulator 44. is reduced by one step. As a result, the pressure of the refrigerant when passing through the pressure regulator 44 can be lowered, and the occurrence of failure of the compressor 11 due to liquid return can be suppressed.

If the time during which the suction superheat SH is less than the target value SHref does not continue for the specified time t2, that is, if NO in step S5, in step S7, the controller 50 operates the electronic solenoid valve that constitutes the pressure regulator 44. Increase the opening by one step. As a result, the pressure on the suction side of the compressor 11 increases, and the occurrence of failure of the compressor 11 can be suppressed.

After steps S4, S6, and S7, in step S8, the controller 50 determines whether or not the defrosting end condition is satisfied. The defrosting end condition is, for example, a condition that the temperature of the refrigerant on the outlet side of the evaporator 14 (hereinafter referred to as "evaporator outlet temperature Tout") rises above a specified temperature Tref. The controller 50 acquires the detected value of the temperature sensor 43 as the evaporator outlet temperature Tout, and determines that the defrosting end condition is satisfied when the evaporator outlet temperature Tout is equal to or higher than the specified temperature Tref. The specified temperature Tref is, for example, 25° C. and is prestored in the controller 50 .

If NO in step S8, the defrost operation control is returned to step S3. In the case of YES in step S8, the controller 50 switches the H/G electromagnetic valve 22 to the closed state in step S9. This completes the defrost operation control.

(advantage)
After describing the configuration and problems of the refrigeration cycle apparatus according to the reference embodiment, advantages of the refrigeration cycle apparatus 1 according to Embodiment 1 will be described.

FIG. 3 is a schematic configuration diagram of a refrigeration cycle apparatus according to a reference embodiment. A refrigerating cycle device 100 according to the reference embodiment has a configuration similar to that of the refrigerating cycle device described in Patent Document 1. Referring to FIG. 3 , refrigeration cycle device 100 includes refrigerant circuit 10 and switching circuit 120 . No pressure regulator 44 is arranged in the refrigerant circuit 10 . The switching circuit 120 is different from the switching circuit 20 shown in FIG. 1 in that it includes a needle valve 122 that is arranged after the H/G solenoid valve 22 in the hot gas bypass pipe 21 . That is, the switching circuit 120 causes the refrigerant discharged from the compressor 11 to be decompressed by the needle valve 122 before flowing into the evaporator 14 .

In the defrost operation, the high-temperature, high-pressure refrigerant discharged from the compressor 11 passes through the H/G solenoid valve 22 and flows through the hot gas bypass pipe 21 . If the high-temperature and high-pressure refrigerant directly flows into the evaporator 14, the state of the refrigerant sucked into the compressor 11 will exceed the operating range of the compressor 11, increasing the possibility of the compressor 11 breaking down. Therefore, as shown in FIG. 3, by providing a needle valve 122 downstream of the H/G solenoid valve 22, the pressure of the refrigerant is reduced. As the refrigerant is decompressed, the temperature of the refrigerant drops, and the refrigerant with a lower pressure and lower temperature than the refrigerant discharged from the compressor 11 flows into the evaporator 14 . As a result, the heat quantity of the refrigerant decreases, and the time required for the defrosting operation becomes longer.

On the other hand, as shown in FIG. 1, the refrigeration cycle apparatus 1 according to Embodiment 1 is a pressure regulator that is arranged on the suction side of the compressor 11 and adjusts the pressure of the refrigerant that is sucked into the compressor 11. 44. Further, the refrigeration cycle apparatus 1 includes a controller 50 that controls the pressure regulator 44 so that the suction pressure Pin and the suction superheat SH are within the first and second specified ranges, respectively, during the defrost operation. .

As a result, even if the high-temperature, high-pressure refrigerant discharged from the compressor 11 flows into the evaporator 14 without being decompressed, the suction pressure Pin and the suction superheat SH are kept within the specified ranges. The pressure applied is regulated. Therefore, the refrigeration cycle device 1 can include a switching circuit 20 that causes the refrigerant discharged from the compressor 11 to flow into the evaporator 14 during the defrost operation. That is, the high-temperature, high-pressure refrigerant discharged from the compressor 11 flows into the evaporator 14 without being decompressed. As a result, the amount of heat of the refrigerant flowing into the evaporator 14 increases, and the frost adhering to the inside of the evaporator 14 can be melted in a short period of time. Furthermore, since the pressure sucked into the compressor 11 is adjusted so that the suction pressure Pin and the suction superheat SH are within specified ranges, the occurrence of failure of the compressor 11 can be suppressed.

As described above, according to the refrigeration cycle apparatus 1 according to Embodiment 1, it is possible to suppress the occurrence of compressor failure and shorten the time required for the defrost operation.

Various known refrigerants may be employed in the refrigerant circuit 10 . However, in order to suppress the global warming potential, it is preferable to employ carbon dioxide (CO ₂ ) refrigerant.

In order to efficiently melt the frost adhered inside the evaporator 14, it is preferable to use not only the sensible heat but also the latent heat of condensation of the refrigerant. In order to use the latent heat of condensation to melt the frost inside the evaporator 14, the refrigerant passing through the evaporator 14 must have a saturation temperature higher than 0.degree. That is, when defrosting operation is performed using _CO2 refrigerant, it is necessary to have a pressure of 3.3 MPa or more in order to have a saturation temperature higher than 0°C.

When the design pressure of the refrigerant circuit is set to 4.15 MPa, which is equivalent to the case of using R410A refrigerant, the pressure of the refrigerant on the discharge side of the compressor 11 is normally higher than the design pressure of 4.15 MPa in consideration of the margin. set low. Therefore, when the refrigeration cycle apparatus is configured as shown in FIG. 3, the pressure of the refrigerant discharged from the compressor 11 is reduced by the needle valve 122, so the pressure of the _CO2 refrigerant in the evaporator 14 must be 3.3 MPa or more. is difficult. That is, when the _CO2 refrigerant is used in the refrigeration cycle apparatus 100 configured as shown in FIG. 3, the frost inside the evaporator 14 cannot be melted efficiently.

However, in the refrigeration cycle apparatus 1 according to Embodiment 1, the high-temperature, high-pressure refrigerant discharged from the compressor 11 can flow into the evaporator 14 without being decompressed. Therefore, even if a _CO2 refrigerant is adopted, the saturation temperature of the refrigerant flowing into the evaporator 14 can be made higher than 0°C, and the latent heat of condensation of the refrigerant can be used to effectively remove the frost inside the evaporator 14. can melt.

Embodiment 2.
FIG. 4 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 2. FIG. As shown in FIG. 4, the refrigerating cycle device 1a according to the second embodiment differs from the refrigerating cycle device 1 according to the first embodiment in that a heat exchanger 45 is further included.

The heat exchanger 45 is arranged between the pressure regulator 44 and the suction side of the compressor 11 in the refrigerant circuit 10 . Specifically, the heat exchanger 45 is arranged between the pressure regulator 44 and the accumulator 15 . The heat exchanger 45 heats the refrigerant with heat from the outside. The heat exchanger 45 exchanges heat, for example, between the air supplied from the blower fan 46 and the refrigerant. The heat exchanger 45 can also be said to be a heat collector.

The flow of control during the defrost operation in the refrigeration cycle apparatus 1a according to Embodiment 2 is the same as the flow chart shown in FIG. Therefore, detailed description is omitted.

The refrigerating cycle device 1a according to the second embodiment has the same effect as the first embodiment. That is, it is possible to suppress the occurrence of failure of the compressor 11 and shorten the time required for the defrost operation. Further, even if the _CO2 refrigerant is used, the latent heat of condensation of the refrigerant can be used to efficiently melt the frost inside the evaporator 14 . Furthermore, according to the refrigeration cycle device 1 a according to Embodiment 2, the refrigerant is heated by the heat exchanger 45 on the suction side of the compressor 11 . Therefore, the degree of superheat of the refrigerant can be increased, and liquid return to the compressor 11 can be suppressed. Furthermore, the defrosting operation time can be shortened because the circulation amount of the refrigerant increases.

Embodiment 3.
FIG. 5 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 3. FIG. As shown in FIG. 5, the refrigerating cycle apparatus 1b according to the third embodiment has a switching circuit 20b and a controller 50b instead of the switching circuit 20 and the controller 50, as compared with the refrigerating cycle apparatus 1a according to the second embodiment. are provided respectively. The switching circuit 20b is different from the switching circuit 20 shown in FIG. 4 in that it further includes a bypass pipe 23 and solenoid valves 24 and 25 .

The bypass pipe 23 connects a branch point 62 between the evaporator 14 and the pressure regulator 44 in the refrigerant circuit 10 and a branch point 63 between the heat exchanger 45 and the suction side of the compressor 11 in the refrigerant circuit 10. Connecting.

The solenoid valve 24 is arranged on the bypass pipe 23 . The solenoid valve 25 is arranged between the branch point 62 and the heat exchanger 45 . Although the solenoid valve 25 is arranged between the branch point 62 and the pressure regulator 44 in the example shown in FIG.

The controller 50b performs the operation of controlling the opening and closing of the solenoid valves 24 and 25 in addition to the operation of the controller 50 described above.

FIG. 6 is a flow chart showing the flow of control during defrost operation in the refrigeration cycle apparatus according to Embodiment 3. FIG. The flowchart shown in FIG. 6 differs from the flowchart shown in FIG. 2 only in that steps S1b and S9b are included instead of steps S1 and S9, respectively.

In step S1b, the controller 50b switches the H/G solenoid valve 22 and the solenoid valve 25 to the open state, and switches the solenoid valve 24 to the closed state. In step S9b, the controller 50b switches the H/G solenoid valve 22 and the solenoid valve 25 to the closed state, and switches the solenoid valve 24 to the open state.

The refrigeration cycle device 1b according to the third embodiment has the same effect as the second embodiment. Further, the solenoid valves 24, 25 of the refrigeration cycle device 1b switch the flow path of the refrigerant from the evaporator 14 to the compressor 11 to a flow path passing through the bypass pipe 23 during cooling operation, and adjust the pressure during defrost operation. switch to the flow path through vessel 44 and heat exchanger 45 . As a result, the refrigerant does not pass through the heat exchanger 45 during the cooling operation. As a result, the pressure loss on the low-pressure side during cooling operation can be suppressed, and the performance of the refrigerant circuit 10 can be improved.

A three-way valve may be arranged at the branch point 62 instead of the solenoid valves 24 and 25 . The three-way valve switches the flow path of the refrigerant from the evaporator 14 to the compressor 11 to a flow path passing through the bypass pipe 23 during cooling operation, and passes through the pressure regulator 44 and heat exchanger 45 during defrosting operation. Controlled to switch to flow path.

Embodiment 4.
FIG. 7 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 4. FIG. As shown in FIG. 7, the refrigerating cycle device 1c according to the fourth embodiment has a switching circuit 20c and a controller 50c instead of the switching circuit 20b and the controller 50b, as compared with the refrigerating cycle device 1b according to the third embodiment. are provided respectively. The switching circuit 20c is different from the switching circuit 20b shown in FIG. 5 in that it further includes a bypass pipe 26 and electromagnetic valves 27 and 28 .

The bypass pipe 26 is a pipe that passes through the heat exchanger 45 from a branch point 64 between the discharge side of the compressor 11 and the condenser 12 and returns to a branch point 65 between the branch point 64 and the condenser 12. .

The solenoid valve 27 is arranged between the branch point 64 and the branch point 65 in the refrigerant circuit 10 . A solenoid valve 28 is arranged on the bypass pipe 26 . Specifically, the solenoid valve 28 is arranged between the branch point 64 and the heat exchanger 45 in the bypass pipe 26 .

The controller 50c controls opening and closing of the solenoid valves 27 and 28 in addition to the operation of the controller 50b.

FIG. 8 is a flow chart showing the flow of control during defrost operation in the refrigeration cycle apparatus according to Embodiment 4. FIG. The flowchart shown in FIG. 8 differs from the flowchart shown in FIG. 6 only in that steps S1c and S9c are included instead of steps S1b and S9b.

In step S1c, the controller 50c switches the H/G solenoid valve 22 and the solenoid valves 25 and 27 to the open state, and switches the solenoid valves 24 and 28 to the closed state. In step S9c, the controller 50c switches the H/G solenoid valve 22 and the solenoid valves 25 and 27 to the closed state, and switches the solenoid valves 24 and 28 to the open state.

The refrigeration cycle device 1c according to the fourth embodiment has the same effects as those of the third embodiment. Further, the solenoid valves 27 and 28 of the refrigeration cycle device 1c switch the flow path of the refrigerant from the discharge side of the compressor 11 to the condenser 12 to a flow path passing through the bypass pipe 26 during the cooling operation, and the defrost operation. Sometimes the flow path is switched to a flow path that does not pass through the bypass pipe 26 . As a result, the heat exchanger 45 operates as part of the condenser during cooling operation. As a result, power consumption in cooling operation can be reduced.

A three-way valve may be arranged at the branch point 64 instead of the solenoid valves 27 and 28 . The three-way valve switches the flow path of the refrigerant from the discharge side of the compressor 11 to the condenser 12 to a flow path passing through the bypass pipe 26 during cooling operation, and a flow path not passing through the bypass pipe 26 during defrosting operation. controlled to switch to

Bypass pipe 26 and solenoid valves 27 and 28 may be applied to refrigeration cycle apparatus 1a of the second embodiment.

Embodiment 5.
FIG. 9 is a diagram showing the schematic configuration of a refrigeration cycle apparatus according to Embodiment 5 and the flow of refrigerant during cooling operation. FIG. 10 is a diagram showing the schematic configuration of a refrigeration cycle apparatus according to Embodiment 5 and the flow of refrigerant during defrost operation. As shown in FIG. 9, the refrigerating cycle apparatus 1d according to the fifth embodiment has a switching circuit 20d and a controller 50d instead of the switching circuit 20 and the controller 50, as compared with the refrigerating cycle apparatus 1 according to the first embodiment. are provided respectively. The switching circuit 20 d includes a bypass pipe 29 , check valves 30 , 31 , 34 , a four-way valve 32 and a pipe 33 .

The bypass pipe 29 connects a branch point 66 between the discharge side of the compressor 11 and the condenser 12 in the refrigerant circuit 10 and a branch point 67 between the condenser 12 and the expansion valve 13 in the refrigerant circuit 10. . A pressure regulator 44 is arranged on the bypass line 29 .

A check valve 30 is arranged on the bypass pipe 29 . For example, check valve 30 is positioned between pressure regulator 44 and junction 66 on bypass line 29 . Check valve 30 opens when the refrigerant flows from branch point 67 to branch point 66 .

The check valve 31 is arranged between the condenser 12 and the branch point 67 in the refrigerant circuit 10 and opens when the refrigerant flows in the direction from the condenser 12 to the branch point 67 .

Check valve 34 is positioned between junction 66 and condenser 12 . The check valve 34 opens when the refrigerant flows from the branch point 66 toward the condenser 12f.

Four ports of the four-way valve 32 are connected to the discharge side of the compressor 11, the branch point 66, the evaporator 14, and the pipe 33, respectively. One end of the pipe 33 is connected to the four-way valve 32 and the other end of the pipe 33 is connected to the suction side of the compressor 11 via the accumulator 15 . The four-way valve 32 is switched between a normal state and a defrosted state. A normal state is a state in which the discharge side of the compressor 11 is connected to the branch point 66 and the evaporator 14 is connected to the suction side of the compressor 11 via the pipe 33 and the accumulator 15 . A defrosted state is a state in which the discharge side of the compressor 11 is connected to the evaporator 14 and the branch point 66 is connected to the suction side of the compressor 11 via the pipe 33 and the accumulator 15 .

The controller 50d differs from the controller 50 in that instead of controlling the opening and closing of the H/G solenoid valve 22, the controller 50d performs switching control of the state of the four-way valve 32. FIG. Specifically, the controller 50d switches the four-way valve 32 to the normal state during the cooling operation, and switches the four-way valve 32 to the defrosted state during the defrosting operation.

In cooling operation, the refrigerant discharged from the compressor 11 passes through a four-way valve 32, a branch point 66, a condenser 12, a check valve 31, a branch point 67, an expansion valve 13, and an evaporator 14, as shown in FIG. , the four-way valve 32 and the accumulator 15 in this order and returns to the compressor 11 . On the other hand, in defrost operation, as shown in FIG. It passes through the branch point 66 , the four-way valve 32 and the accumulator 15 in this order and returns to the compressor 11 .

FIG. 11 is a flow chart showing the flow of control during defrost operation in the refrigeration cycle apparatus according to Embodiment 5. FIG. The flowchart shown in FIG. 11 differs from the flowchart shown in FIG. 2 only in that steps S1d and S9d are included instead of steps S1 and S9, respectively.

In step S1d, the controller 50d switches the four-way valve 32 to the defrosted state. In step S9d, the controller 50d switches the four-way valve 32 to the normal state.

In step S8, similarly to the first embodiment, the controller 50d acquires, for example, the value detected by the temperature sensor 43 as the evaporator outlet temperature Tout, and determines whether the evaporator outlet temperature Tout is equal to or higher than the specified temperature Tref. do. The direction of refrigerant flow in evaporator 14 during defrost operation in the fifth embodiment is opposite to the direction of refrigerant flow in evaporator 14 during defrost operation in the first embodiment. Therefore, in Embodiment 5, the temperature sensor 43 is arranged near the port of the evaporator 14 on the expansion valve 13 side, and detects the temperature of the refrigerant immediately after passing through the evaporator 14 during the defrost operation.

The refrigerating cycle device 1d according to the fifth embodiment can also achieve the same effects as the refrigerating cycle device 1 according to the first embodiment. That is, it is possible to suppress the occurrence of failure of the compressor 11 and shorten the time required for the defrost operation. Further, even if the _CO2 refrigerant is used, the latent heat of condensation of the refrigerant can be used to efficiently melt the frost inside the evaporator 14 .

Embodiment 6.
FIG. 12 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 6. FIG. As shown in FIG. 12, a refrigerating cycle device 1e according to Embodiment 6 differs from refrigerating cycle device 1d according to Embodiment 5 in that a heat exchanger 45 is further included.

The heat exchanger 45 is arranged between the four-way valve 32 and the branch point 66 in the refrigerant circuit 10 . The heat exchanger 45 heats the refrigerant with heat from the outside, as in the second to fourth embodiments. That is, the heat exchanger 45 exchanges heat between the air supplied from the blower fan 46 and the refrigerant.

The flow of control during the defrost operation in the refrigeration cycle apparatus 1e according to Embodiment 6 is the same as the flow chart shown in FIG. Therefore, detailed description is omitted.

According to the refrigeration cycle apparatus 1e according to Embodiment 6, the refrigerant that has passed through the evaporator 14 is heated in the heat exchanger 45 in the defrost operation. Therefore, the degree of superheat of the refrigerant sucked into the compressor 11 can be increased, and liquid return to the compressor 11 can be suppressed as in the second to fourth embodiments. Furthermore, the defrosting operation time can be shortened because the circulation amount of the refrigerant increases.

Furthermore, during cooling operation, the refrigerant discharged from the compressor 11 passes through the heat exchanger 45 . Therefore, the heat exchanger 45 operates as part of the condenser, as in the fourth embodiment. As a result, power consumption in cooling operation can be reduced.

Thus, the refrigerating cycle device 1e according to the sixth embodiment has the same effects as the refrigerating cycle device 1c according to the fourth embodiment. In a refrigeration cycle apparatus 1c according to Embodiment 4 shown in FIG. 7, a switching circuit 20c has a hot gas bypass pipe 21 and bypass pipes 23 and . In contrast, in the refrigeration cycle apparatus 1 e according to Embodiment 6, the switching circuit 20 e has the bypass pipe 29 and the pipe 33 . Thus, the refrigerating cycle device according to the sixth embodiment can reduce the number of pipes compared to the refrigerating cycle device 1c according to the fourth embodiment.

Embodiment 7.
13 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 7. FIG. As shown in FIG. 13, a refrigeration cycle device 1f according to Embodiment 7 is a dual refrigeration device. Compared with the refrigeration cycle device 1e according to Embodiment 6, the refrigeration cycle device 1f includes a low temperature side refrigerant circuit 10f instead of the refrigerant circuit 10, and further includes a high temperature side refrigerant circuit 70 different from the low temperature side refrigerant circuit 10f. It is different in that it has

The low-temperature side refrigerant circuit 10 f differs from the refrigerant circuit 10 shown in FIG. 12 in that it includes a condenser 12 f instead of the condenser 12 . A low temperature side refrigerant circulates in the low temperature side refrigerant circuit 10f.

The high temperature side refrigerant circuit 70 is a circuit in which a high temperature side compressor 71, a high temperature side condenser 72, a high temperature side expansion valve 73 and a condenser 12f are connected by piping. A high temperature side refrigerant circulates in the high temperature side refrigerant circuit 70 . When the high temperature side compressor 71 is driven, the high temperature side refrigerant passes through the high temperature side compressor 71, the high temperature side condenser 72, the high temperature side expansion valve 73, and the condenser 12f in this order, and returns to the high temperature side compressor 71.

The high temperature side compressor 71 compresses gaseous high temperature side refrigerant. The high temperature side refrigerant discharged from the high temperature side compressor 71 is sent to the high temperature side condenser 72 . The high temperature side condenser 72 condenses the gaseous high temperature side refrigerant discharged from the high temperature side compressor 71 . The high temperature side condenser 72 performs heat exchange between the air supplied from the condenser fan 74 and the high temperature side refrigerant, for example, and cools and condenses the high temperature side refrigerant. The high temperature side refrigerant condensed by the high temperature side condenser 72 is sent to the high temperature side expansion valve 73 . The high temperature side expansion valve 73 expands the liquid high temperature side refrigerant from the high temperature side condenser 72 to reduce the pressure. The high temperature side refrigerant decompressed by the high temperature side expansion valve 73 is sent to the condenser 12f.

The condenser 12 f is a cascade heat exchanger that exchanges heat between the low temperature side refrigerant from the compressor 11 and the high temperature side refrigerant from the high temperature side expansion valve 73 . In the condenser 12f, heat is transferred from the low temperature side refrigerant to the high temperature side refrigerant, thereby cooling the low temperature side refrigerant and heating the high temperature side refrigerant. After being evaporated by heating, the high temperature side refrigerant is sent from the condenser 12 f to the high temperature side compressor 71 . After being condensed in the condenser 12f, the low temperature side refrigerant is sent to the expansion valve 13 in a liquid state.

According to Embodiment 7, the low temperature side refrigerant and the high temperature side refrigerant can be freely selected. Furthermore, power consumption can be suppressed by optimizing the selection of the low temperature side refrigerant and the high temperature side refrigerant. For example, a _CO2 refrigerant is selected as the low temperature side refrigerant, and an HFO refrigerant (HFO1234yf, HFO1234ze, etc.) is selected as the high temperature side refrigerant.

FIG. 13 shows a refrigerating cycle device 1f in which the high temperature side refrigerant circuit 70 and the condenser 12f are applied to the refrigerating cycle device 1e of the sixth embodiment. However, the high temperature side refrigerant circuit 70 and the condenser 12f may be applied to any of the refrigeration cycle apparatuses 1, 1a to 1d of the first to fifth embodiments. That is, in any one of the refrigeration cycle devices 1, 1a to 1d, the condenser 12 may be replaced with the condenser 12f, and the high temperature side refrigerant circuit 70 may be added.

The embodiments disclosed this time should be considered as examples and not restrictive in all respects. The scope of the present invention is indicated by the scope of the claims rather than the description of the above-described embodiments, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

Reference Signs List 1, 1a to 1f, 100 refrigerating cycle device, 10 refrigerant circuit, 10f low-temperature side refrigerant circuit, 11 compressor, 12, 12f condenser, 13 expansion valve, 14 evaporator, 15 accumulator, 16, 74 condenser fan, 17 , 46 blower fan, 20, 20b to 20e, 120 switching circuit, 21 hot gas bypass pipe, 22 H/G solenoid valve, 24, 25, 27, 28 solenoid valve, 23, 26, 29 bypass pipe, 30, 31, 34 check valve, 32 four-way valve, 33 piping, 41 pressure sensor, 42, 43 temperature sensor, 44 pressure regulator, 45 heat exchanger, 50, 50b to 50d controller, 60 to 67 branch point, 70 high temperature side refrigerant circuit , 71 high temperature side compressor, 72 high temperature side condenser, 73 high temperature side expansion valve, 122 needle valve.

Claims (3)

A refrigeration cycle device comprising a refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are connected by piping,
A switching circuit for switching between a cooling operation in which refrigerant is circulated in the order of the compressor, the condenser, the expansion valve, and the evaporator, and a defrost operation in which the refrigerant discharged from the compressor flows into the evaporator. and,
a detection unit for detecting the pressure and degree of superheat of the refrigerant sucked into the compressor;
a pressure regulator for adjusting the pressure of the refrigerant sucked into the compressor;
a controller for controlling the pressure regulator so that the pressure and the degree of superheat detected by the detection unit fall within a specified range during the defrost operation;
The switching circuit is
a four-way valve;
a fourth bypass pipe connecting a fourth branch point between the condenser and the expansion valve and a fifth branch point between the condenser and the four-way valve;
a first check valve disposed between the condenser and the fourth branch point and opened when the refrigerant flows from the condenser toward the fourth branch point;
a second check valve arranged on the fourth bypass pipe and opened when the refrigerant flows in a direction from the fourth branch point toward the fifth branch point ;
a third check valve disposed between the fifth branch point and the condenser and opened when the refrigerant flows from the fifth branch point toward the condenser;
The pipe between the condenser and the fourth branch point is not branched,
The pressure regulator is arranged on the fourth bypass pipe,
The four-way valve connects the discharge side of the compressor and the condenser during the cooling operation, connects the evaporator and the suction side of the compressor, and connects the compressor during the defrost operation. connecting the discharge side of and the evaporator and connecting the condenser and the suction side of the compressor;
further comprising a heat exchanger that is arranged between the fifth branch point and the four-way valve and heats the refrigerant with heat from the outside;
The heat exchanger operates as part of a condenser that condenses the refrigerant discharged from the compressor during the cooling operation, and condenses the refrigerant that has passed through the evaporator during the defrost operation. A refrigeration cycle device that heats. Further comprising a refrigerant circuit different from the refrigerant circuit,
2. The refrigeration cycle apparatus according to claim 1, wherein said condenser exchanges heat between said refrigerant flowing through said refrigerant circuit and refrigerant flowing through said another refrigerant circuit. 3. The refrigeration cycle apparatus according to claim 1, wherein said refrigerant flowing through said refrigerant circuit is a _CO2 refrigerant.

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