JP7630648B2 - Refrigeration Cycle Equipment - Google Patents

Description

The present disclosure relates to a refrigeration cycle device equipped with a refrigerant circuit.

Conventionally, refrigeration cycle devices such as refrigeration units and air conditioners circulate a refrigerant through a refrigeration cycle circuit to perform cooling or heating operations, and exchange heat between the refrigerant and a fluid such as air, water or brine.

In a refrigeration cycle device, an excess or shortage of refrigerant not only reduces the capacity of the refrigeration cycle device, but can also cause damage to the equipment that makes up the refrigeration cycle circuit. To prevent such problems from occurring, there are refrigeration cycle devices that have a function to determine whether the amount of refrigerant filled in the refrigeration cycle circuit is excessive or insufficient.

Conventionally, an example of a refrigeration device that determines whether or not the amount of refrigerant is insufficient has been proposed (see, for example, Patent Document 1). The refrigeration device disclosed in Patent Document 1 determines whether or not there is a leak of the refrigerant filled in the refrigerant circuit based on the temperature efficiency of the subcooling heat exchanger, which is the value obtained by dividing the degree of subcooling of the refrigerant at the outlet of the subcooling heat exchanger by the maximum temperature difference of the subcooling heat exchanger.

Patent No. 5674452

The refrigeration system disclosed in Patent Document 1 determines whether or not there is a refrigerant leak based on a temperature efficiency calculated using the degree of subcooling at the outlet of the subcooling heat exchanger while the compressor is operating and a preset determination threshold. However, if the compressor repeatedly starts and stops in short cycles, the temperature and pressure of the refrigerant flowing through each refrigeration device, including the subcooling heat exchanger, will not stabilize. In this case, the refrigeration system will not be able to correctly determine whether or not there is a refrigerant leak, and there is a risk of an erroneous determination.

On the other hand, if the refrigeration system disclosed in Patent Document 1 attempts to determine the presence or absence of a refrigerant leak when the compressor is not operating in order to prevent erroneous determination, the changes in the temperature and pressure of the refrigerant in each refrigerant device will be small. Therefore, the difference in the refrigerant temperature and pressure in each refrigerant device between a normal case where there is no refrigerant leak and a case where there is a refrigerant leak will not be easily reflected in the temperature efficiency of the subcooling heat exchanger. As a result, there is a risk that the accuracy of determining the presence or absence of a refrigerant leak will decrease.

The present disclosure has been made to solve the problems described above, and provides a refrigeration cycle device that can accurately detect refrigerant leakage when the compressor is stopped.

The refrigeration cycle apparatus according to the present disclosure includes a refrigerant circuit in which a compressor, a condenser, and an evaporator are connected by a refrigerant piping and a refrigerant circulates through the refrigerant piping, a low pressure sensor provided between the compressor and the evaporator and detecting a low pressure which is the pressure of the refrigerant flowing through the refrigerant piping, a flow control valve provided between the condenser and the evaporator, and a controller for controlling the compressor and the flow control valve, wherein the controller includes valve control means for opening the flow control valve until the elapsed time since the compressor stopped becomes equal to or greater than a reference time which ensures a certain operating time of the compressor in pump-down operation, and then switching the flow control valve from the open state to a closed state, compressor control means for causing the compressor to perform the pump-down operation in which the refrigerant in the refrigerant circuit is recovered to the condenser when the flow control valve is switched from the open state to the closed state, and determination means for determining whether or not the refrigerant is leaking based on a state of equipment constituting the refrigerant circuit or the refrigerant when the compressor finishes the pump-down operation.

According to the present disclosure, when the compressor is stopped, a series of processes are carried out, from increasing the low pressure in the refrigerant circuit to recovering the refrigerant in the condenser. As a result, the range of change in the temperature and pressure of the refrigerant in each device and between the devices in the refrigerant circuit becomes large, and the difference from the temperature and pressure of the refrigerant in a normal state without refrigerant leakage becomes noticeable. Because a state suitable for refrigerant leakage determination is created, refrigerant leakage can be detected with high accuracy even when the compressor is stopped.

1 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle device according to a first embodiment. FIG. 2 is a functional block diagram showing a configuration example of a controller shown in FIG. 1 . 3 is a hardware configuration diagram showing an example of the configuration of a controller shown in FIG. 2 . 3 is a hardware configuration diagram showing another example of the configuration of the controller shown in FIG. 2. 4 is a flowchart showing an example of an operation procedure of the refrigeration cycle device according to the first embodiment. FIG. 4 is a refrigerant circuit diagram showing another configuration example of the refrigeration cycle device according to the first embodiment. FIG. 13 is a functional block diagram showing a configuration example of a controller shown in FIG. 1 in a refrigeration cycle device according to a second embodiment. FIG. 11 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle device according to a third embodiment. FIG. 9 is a functional block diagram showing a configuration example of a controller shown in FIG. 8 . FIG. 11 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle device according to a fourth embodiment. FIG. 11 is a functional block diagram showing a configuration example of a controller shown in FIG. 10 . FIG. 13 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle device according to a fifth embodiment. 13 is a functional block diagram showing a configuration example of a controller shown in FIG. 12. 13 is a flowchart showing an operation procedure of a refrigeration cycle device according to a fifth embodiment. FIG. 13 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle device according to a sixth embodiment. FIG. 13 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle device according to a seventh embodiment. FIG. 17 is a functional block diagram showing a configuration example of a controller shown in FIG. 16 . FIG. 13 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle device according to an eighth embodiment. FIG. 19 is a functional block diagram showing a configuration example of a controller shown in FIG. 18 .

Embodiment 1.
The configuration of the refrigeration cycle apparatus according to the present embodiment 1 will be described. Fig. 1 is a refrigerant circuit diagram showing an example of the configuration of the refrigeration cycle apparatus according to the embodiment 1. As shown in Fig. 1, the refrigeration cycle apparatus 200 has a heat source side unit 100 and a load side unit 110.

The heat source unit 100 is installed outdoors. The heat source unit 100 generates heat to be supplied to the load unit 110. The load unit 110 is installed in an air-conditioned space which is the source of the thermal load of the refrigeration cycle device 200. The load unit 110 supplies the heat supplied from the heat source unit 100 to the thermal load. In this embodiment 1, the air-conditioned space is a room in which one or both of objects and people that generate heat are present, and the load unit 110 cools the air in the room.

The heat source side unit 100 has a compressor 1, a heat source side heat exchanger functioning as a condenser 4, and a controller 30. The load side unit 110 has a pressure reducing device 11 and a load side heat exchanger functioning as an evaporator 12. The compressor 1, the condenser 4, the pressure reducing device 11, and the evaporator 12 are connected by a refrigerant piping 21 to form a refrigerant circuit 20 in which the refrigerant circulates. In this embodiment 1, a flow control valve 10 is provided in the refrigerant piping 21 between the condenser 4 and the pressure reducing device 11.

The compressor 1 draws in low-temperature and low-pressure refrigerant, compresses the drawn refrigerant, and discharges it as high-temperature and high-pressure refrigerant. The compressor 1 is, for example, an inverter compressor whose capacity can be adjusted by changing the operating frequency fc. The condenser 4 exchanges heat between the fluid and the refrigerant. The condenser 4 condenses the refrigerant by dissipating heat from the refrigerant. The fluid that exchanges heat with the refrigerant in the condenser 4 is outside air. The condenser 4 is, for example, a fin-and-tube type heat exchanger having a heat transfer tube and multiple heat dissipation fins. The compressor 1 is connected to the controller 30 via a signal line 25.

The pressure reducing device 11 reduces the pressure of the liquid refrigerant flowing in from the condenser 4 and expands it. The pressure reducing device 11 also adjusts the flow rate of the refrigerant flowing in from the condenser 4. The pressure reducing device 11 is, for example, an expansion valve. In the first embodiment, the pressure reducing device 11 is an expansion valve. The evaporator 12 exchanges heat between the fluid and the refrigerant. The evaporator 12 absorbs heat from the refrigerant that has been reduced in pressure and expanded by the pressure reducing device 11 to evaporate the refrigerant. The fluid that exchanges heat with the refrigerant in the evaporator 12 is the air in the space to be air-conditioned. The evaporator 12 is, for example, a fin-and-tube type heat exchanger having a heat transfer tube and multiple heat dissipation fins. The pressure reducing device 11 is connected to the controller 30 via a signal line (not shown).

In the heat source unit 100, a low pressure sensor 9 is provided on the refrigerant suction port side of the compressor 1. The low pressure sensor 9 detects the suction pressure, which is the pressure of the refrigerant sucked into the compressor 1. The suction pressure corresponds to the low pressure Lp, which is the pressure on the low pressure side in the refrigerant circuit 20. In addition, a high pressure sensor 3 is provided on the refrigerant discharge port side of the compressor 1. The high pressure sensor 3 detects the discharge pressure, which is the pressure of the refrigerant discharged from the compressor 1. The discharge pressure corresponds to the high pressure Hp, which is the pressure on the high pressure side in the refrigerant circuit 20. The low pressure sensor 9 and the high pressure sensor 3 are connected to the controller 30 via a signal line (not shown).

The load side unit 110 is provided with a room temperature sensor 23 that detects the room temperature. The room temperature sensor 23 is, for example, a thermistor. The room temperature sensor 23 is connected to the controller 30 via a signal line (not shown). The load side unit 110 is provided with an alarm device 50 that notifies the user that a refrigerant leak has occurred. The alarm device 50 is connected to the controller 30 via a signal line (not shown).

The alarm device 50, for example, has one or both of a display (not shown) that displays information and a speaker (not shown) that outputs an alarm sound. When the alarm device 50 has a display (not shown), upon receiving a refrigerant leakage alarm signal from the controller 30 indicating that refrigerant is leaking, the alarm device 50 displays a message indicating that refrigerant is leaking on the display (not shown). When the alarm device 50 has a speaker (not shown), upon receiving a refrigerant leakage alarm signal from the controller 30, the alarm device 50 outputs an alarm sound to the speaker (not shown).

The flow control valve 10 is, for example, a solenoid valve. The opening and closing of the flow control valve 10 is controlled by the controller 30. The flow control valve 10 maintains an open state while the compressor 1 is in operation. The flow control valve 10 is connected to the controller 30 via a signal line (not shown).

Next, the configuration of the controller 30 will be described. Figure 2 is a functional block diagram showing an example of the configuration of the controller shown in Figure 1. The controller 30 is, for example, a microcomputer. The controller 30 has a refrigeration cycle control means 31, a valve control means 32, a compressor control means 33, a determination means 34, and a timer 35 that measures time.

When the operation mode of the load side unit 110 is cooling operation, the refrigeration cycle control means 31 controls the compressor 1 and the pressure reducing device 11 so that the room temperature detected by the room temperature sensor 23 matches the set temperature. Specifically, the refrigeration cycle control means 31 calculates the operating frequency fc of the compressor 1 and the opening degree ve of the pressure reducing device 11 that brings the room temperature close to the set temperature or maintains the room temperature at the set temperature at a predetermined constant period. The refrigeration cycle control means 31 then transmits information on the calculated opening degree ve to the valve control means 32 and transmits information on the calculated operating frequency fc to the compressor control means 33. The set temperature is input to the controller 30 by the user.

When the valve control means 32 receives information on the opening degree ve from the refrigeration cycle control means 31, it controls the opening degree of the pressure reducing device 11 so that the opening degree becomes ve. In addition, the valve control means 32 opens the flow control valve 10 until a first condition is satisfied in which the low pressure Lp detected by the low pressure sensor 9 becomes equal to or greater than a predetermined reference value Pref when the compressor 1 is stopped. The valve control means 32 may open the flow control valve 10 until a second condition is satisfied in which the elapsed time from when the compressor 1 is stopped becomes equal to or greater than a predetermined reference time tref. The valve control means 32 determines the elapsed time from when the compressor 1 is stopped by referring to the time measured by the timer 35. In addition, the valve control means 32 may open the flow control valve 10 until both the first condition and the second condition are satisfied. When one or both of the first condition and the second condition are satisfied, the valve control means 32 switches the flow control valve 10 from an open state to a closed state.

When the compressor control means 33 receives information on the operating frequency fc from the refrigeration cycle control means 31, it operates the compressor 1 at the operating frequency fc. In addition, when the flow control valve 10 switches from an open state to a closed state while the compressor 1 is stopped, the compressor control means 33 causes the compressor 1 to perform a pump-down operation. The pump-down operation is a process in which the compressor 1 is operated for the purpose of recovering refrigerant in the condenser 4 until the low pressure Lp falls to a predetermined end pressure value.

When the compressor 1 finishes pump-down operation, the determination means 34 performs a refrigerant leakage determination process to determine whether or not the refrigerant is leaking based on the state of the equipment and refrigerant that constitute the refrigerant circuit 20. For example, if the determination parameter for determining whether or not the refrigerant is leaking is the high-pressure pressure Hp, the determination means 34 determines whether or not the high-pressure pressure Hp is equal to or lower than a predetermined pressure threshold Pth. If the refrigerant is leaking, the high-pressure pressure Hp after the pump-down operation tends to be lower than in a normal case where the refrigerant is not leaking. Therefore, if the high-pressure pressure Hp is equal to or lower than the pressure threshold Pth as a result of the determination, the determination means 34 determines that the refrigerant is leaking. On the other hand, if the high-pressure pressure Hp is greater than the pressure threshold Pth, the determination means 34 determines that the refrigerant is not leaking. If the determination means 34 determines that the refrigerant is leaking, it transmits a refrigerant leakage notification signal to the notification device 50.

Here, an example of the hardware of the controller 30 shown in Figure 2 will be described. Figure 3 is a hardware configuration diagram showing an example of the configuration of the controller shown in Figure 2. When the various functions of the controller 30 are executed by hardware, the controller 30 shown in Figure 2 is configured by a processing circuit 90 as shown in Figure 3. Each function of the refrigeration cycle control means 31, valve control means 32, compressor control means 33, determination means 34 and timer 35 shown in Figure 2 is realized by the processing circuit 90.

When each function is executed by hardware, the processing circuit 90 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination of these. Each of the functions of the refrigeration cycle control means 31, the valve control means 32, the compressor control means 33, the determination means 34, and the timer 35 may be realized by the processing circuit 90. Also, the functions of each of the refrigeration cycle control means 31, the valve control means 32, the compressor control means 33, the determination means 34, and the timer 35 may be realized by a single processing circuit 90.

Another example of the hardware of the controller 30 shown in FIG. 2 will be described. FIG. 4 is a hardware configuration diagram showing another example of the configuration of the controller shown in FIG. 2. When the various functions of the controller 30 are executed by software, the controller 30 shown in FIG. 2 is composed of a processor 91 such as a CPU (Central Processing Unit) and a memory 92, as shown in FIG. 4. The functions of the refrigeration cycle control means 31, the valve control means 32, the compressor control means 33, the determination means 34, and the timer 35 are realized by the processor 91 and the memory 92. FIG. 4 shows that the processor 91 and the memory 92 are connected to each other so as to be able to communicate with each other via a bus 93.

When each function is executed by software, the functions of the refrigeration cycle control means 31, valve control means 32, compressor control means 33, determination means 34 and timer 35 are realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in memory 92. The processor 91 realizes the function of each means by reading and executing the programs stored in memory 92.

As the memory 92, for example, a non-volatile semiconductor memory such as a ROM (Read Only Memory), a flash memory, an EPROM (Erasable and Programmable ROM), and an EEPROM (Electrically Erasable and Programmable ROM) is used. Also, as the memory 92, a volatile semiconductor memory such as a RAM (Random Access Memory) may be used. Furthermore, as the memory 92, a removable recording medium such as a magnetic disk, a flexible disk, an optical disk, a CD (Compact Disc), an MD (Mini Disc), and a DVD (Digital Versatile Disc) may be used.

1 shows a configuration in which the controller 30 is provided in the heat source unit 100, but the controller 30 may be provided in the load unit 110. FIG. 1 shows a configuration in which the flow control valve 10 and the pressure reducing device 11 are provided in the load unit 110, but one or both of the flow control valve 10 and the pressure reducing device 11 may be provided in the heat source unit 100. In addition, in this embodiment 1, the case where the alarm device 50 is provided in the refrigeration cycle device 200 is described, but the alarm device 50 does not have to be provided. The case where the controller 30 and the equipment such as the compressor 1 and the sensors such as the low pressure sensor 9 are connected by wires has been described, but they may be connected wirelessly.

The refrigeration cycle device 200 of this embodiment 1 is characterized in that while the compressor 1 is stopped, the flow control valve 10 is opened to increase the low pressure Lp, and then the flow control valve 10 is closed, and then a pump-down operation is performed before determining whether or not there is a refrigerant leak.

Next, the operation of the refrigeration cycle apparatus 200 of the first embodiment will be described. FIG. 5 is a flowchart showing an example of an operating procedure of the refrigeration cycle apparatus according to the first embodiment. Here, the first of two conditions for maintaining the flow control valve 10 in an open state from when the compressor 1 stops will be described. The refrigeration cycle apparatus 200 performs the process shown in FIG. 5, for example, during a time period when it is not operating.

When a user inputs an instruction to stop the refrigeration cycle device 200, the refrigeration cycle control means 31 transmits a stop signal, which is a signal instructing the compressor 1 to be stopped, to the compressor control means 33. When the compressor control means 33 receives the stop signal from the refrigeration cycle control means 31, it stops the compressor 1 (step S101).

The valve control means 32 maintains the flow control valve 10 in an open state while the compressor 1 is stopped (step S102). This causes the refrigerant on the high-pressure side to move to the low-pressure side, and the low-pressure pressure Lp increases. The controller 30 waits until the low-pressure pressure Lp increases to the reference value Pref. The purpose of increasing the low-pressure pressure Lp is to ensure a certain period of operation of the compressor 1 during the subsequent pump-down operation, thereby increasing the range of change in temperature and pressure of the refrigerant in each device of the refrigerant circuit 20 and between the devices.

The valve control means 32 determines whether the low pressure Lp is equal to or greater than the reference value Pref (step S103). When the low pressure Lp is equal to or greater than the reference value Pref, the valve control means 32 switches the flow control valve 10 from an open state to a closed state (step S104). When the flow control valve 10 switches from an open state to a closed state, the compressor control means 33 starts the compressor 1 (step S105) and causes the compressor 1 to perform a pump-down operation. As a result, the refrigerant in the refrigerant circuit 20 is recovered in the condenser 4. The compressor control means 33 determines whether the recovery of the refrigerant in the refrigerant circuit 20 has been completed (step S106). Specifically, the compressor control means 33 determines whether the low pressure Lp has been reduced to the end pressure value. When the low pressure Lp is reduced to the end pressure value, the compressor control means 33 determines that the recovery of the refrigerant to the condenser 4 has been completed. When it is determined in the process of step S106 that the recovery of the refrigerant has been completed, the compressor control means 33 stops the compressor 1 (step S107) and ends the pump-down operation.

After processing in step S107, the judgment means 34 uses the judgment parameter to judge whether or not refrigerant is leaking. In this embodiment 1, the judgment parameter is the high pressure pressure Hp. The judgment means 34 judges whether or not the high pressure pressure Hp is equal to or lower than the pressure threshold value Pth (step S108). If the high pressure pressure Hp is equal to or lower than the pressure threshold value Pth, the judgment means 34 judges that refrigerant is leaking (step S109). This is because if refrigerant is leaking, the high pressure pressure Hp after pump-down operation will be lower than in the normal case. In step S109, the judgment means 34 may transmit a refrigerant leakage notification signal to the notification device 50.

On the other hand, if the result of the judgment in step S108 is that the high pressure Hp is greater than the pressure threshold Pth and the judgment means 34 judges that the refrigerant is not leaking, the controller 30 ends the process. Next, after the refrigeration cycle device 200 starts operating, the controller 30 suspends the process in step S101 until an instruction to stop the refrigeration cycle device 200 is input from the user.

In this way, the refrigeration cycle device 200 increases the low pressure Lp while the compressor 1 is stopped, closes the flow control valve 10, and then performs pump-down operation before determining whether or not there is a refrigerant leak. By performing a series of processes from increasing the low pressure LP to recovering the refrigerant to the condenser 4, the temperature and pressure of the refrigerant in each device of the refrigerant circuit 20 and between the devices changes to a greater extent, and the difference from the temperature or pressure of the refrigerant in a normal state without refrigerant leakage becomes more noticeable. Therefore, the refrigeration cycle device 200 can accurately detect a refrigerant leak even when the compressor 1 is stopped, and can take early action against the refrigerant leak.

In the processing of steps S101 to S102 shown in FIG. 5, when the compressor control means 33 stops the compressor 1, the valve control means 32 maintains the flow control valve 10 in the open state. However, the valve control means 32 may temporarily close the flow control valve 10. In this case, the valve control means 32 may switch the flow control valve 10 from the closed state to the open state in step S102 after a period of time has elapsed until the refrigerant pressures on the high-pressure side and low-pressure side of the refrigerant circuit 20 have stabilized. The period of time until the refrigerant pressures on the high-pressure side and low-pressure side of the refrigerant circuit 20 have stabilized is, for example, 30 minutes or more.

An example of the case where the valve control means 32 closes the flow control valve 10 after the compressor 1 stops will be described. For example, if the refrigeration cycle device 200 does not operate for several days after the compressor 1 stops, the valve control means 32 closes the flow control valve 10. In this case, the controller 30 determines the presence or absence of refrigerant leakage once a day according to the flow shown in FIG. 5. In this case, even if the refrigeration cycle device 200 stops for a long period of time, the controller 30 determines the presence or absence of refrigerant leakage once a day. This makes it possible to prevent refrigerant from leaking for a long period of time.

The refrigeration cycle device 200 of the present embodiment 1 has a refrigerant circuit 20 in which the compressor 1, the condenser 4, and the evaporator 12 are connected by a refrigerant pipe 21 and the refrigerant circulates through the refrigerant pipe 21, a low pressure sensor 9, a flow control valve 10, and a controller 30. The low pressure sensor 9 is provided between the compressor 1 and the evaporator 12 and detects a low pressure Lp, which is the pressure of the refrigerant circulating through the refrigerant pipe 21. The flow control valve 10 is provided between the condenser 4 and the evaporator 12. The controller 30 controls the compressor 1 and the flow control valve 10. The controller 30 has a valve control means 32, a compressor control means 33, and a determination means 34. The valve control means 32 opens the flow control valve 10 until one or both of the first and second conditions are satisfied while the compressor 1 is stopped, and then switches the flow control valve 10 from the open state to the closed state. The first condition is that the low pressure Lp becomes equal to or greater than a reference value Pref when the compressor 1 is stopped. The second condition is that the elapsed time since the compressor 1 was stopped becomes equal to or greater than a reference time tref. When the flow control valve 10 is switched from an open state to a closed state, the compressor control means 33 causes the compressor 1 to perform a pump-down operation for recovering the refrigerant in the refrigerant circuit 20 to the condenser 4. When the compressor 1 ends the pump-down operation, the determination means 34 determines whether or not refrigerant is leaking based on the state of the devices or refrigerant constituting the refrigerant circuit 20.

As disclosed in Patent Document 1, for example, some conventional refrigeration systems use the temperature and pressure of the refrigerant in the refrigerant equipment while the compressor is operating to determine whether or not there is a refrigerant leak. However, when the compressor repeatedly starts and stops in short cycles, the temperature and pressure of the refrigerant flowing through each refrigerant equipment, including the subcooling heat exchanger, are not stable, and there is a risk of erroneous determination of the presence or absence of a refrigerant leak.

On the other hand, when a conventional refrigeration system tries to determine whether or not there is a refrigerant leak when the compressor is not operating in order to prevent erroneous determination, the changes in refrigerant temperature and pressure in each refrigerant device become small. As a result, the difference in refrigerant temperature and pressure in the refrigerant device between a normal state where there is no refrigerant leak and a state where there is a refrigerant leak is not easily reflected in the determination parameters. As a result, in conventional refrigeration systems, there is a risk that the accuracy of determining whether or not there is a refrigerant leak will decrease.

In contrast, the refrigeration cycle device 200 of the present embodiment 1 opens the flow control valve 10 while the compressor 1 is stopped to increase the low pressure Lp, then closes the flow control valve 10, and performs pump-down operation before determining whether or not there is a refrigerant leak. According to the present embodiment 1, when the compressor 1 is stopped, a series of processes are performed from the increase in the low pressure LP to the recovery of the refrigerant to the condenser 4. As a result, the range of change in the temperature and pressure of the refrigerant of each device and between the devices in the refrigerant circuit 20 becomes large, and the difference from the temperature and pressure of the refrigerant in a normal case without refrigerant leakage becomes noticeable. Since a state suitable for refrigerant leakage determination is generated, the refrigeration cycle device 200 can accurately detect a refrigerant leak even when the change in the temperature or pressure of the refrigerant is small, that is, when the compressor 1 is stopped. As a result, the refrigeration cycle device 200 can take early action against a refrigerant leak.

(Variation 1)
In the refrigeration cycle apparatus 200 of the first embodiment, the flow rate control valve 10 may have a function as the pressure reducing device 11. FIG. 6 is a refrigerant circuit diagram showing another configuration example of the refrigeration cycle apparatus according to the first embodiment. When the refrigeration cycle apparatus 200 performs cooling operation, the valve control means 32 may control the flow rate control valve 10 to function as the pressure reducing device 11. In this case, it is not necessary to separately provide the pressure reducing device 11 shown in FIG. 1 in the refrigerant circuit. On the other hand, in the case of the configuration example described with reference to FIG. 1, the flow rate control valve 10 may have at least a function as an opening/closing valve that switches between an open state and a closed state.

Embodiment 2.
In the first embodiment, a series of processes from the increase in the low pressure LP to the recovery of the refrigerant in the condenser 4 is performed to create a state suitable for refrigerant leakage determination, and then the presence or absence of refrigerant leakage is determined using the high pressure Hp as a determination parameter. In the second embodiment, the presence or absence of refrigerant leakage is determined using the time of the pump-down operation as a determination parameter. In the second embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The configuration of the refrigeration cycle device of the second embodiment will be described. The overall configuration of the refrigeration cycle device 200 of the second embodiment is similar to that described with reference to Figure 1, so detailed description of each component will be omitted. Figure 7 is a functional block diagram showing an example configuration of the controller shown in Figure 1 in the refrigeration cycle device of the second embodiment.

The determination means 34 in the second embodiment determines whether the time of the pump-down operation is shorter than a predetermined time threshold value tith. When refrigerant is leaking, the amount of refrigerant in the refrigerant circuit 20 decreases, so when the compressor 1 performs pump-down operation after the low-pressure pressure Lp reaches the reference value, the time required for the pump-down operation to end tends to be shorter. In other words, the time required for the low-pressure pressure Lp to drop to the end pressure value tends to be shorter than in a normal case where there is no refrigerant leakage. Therefore, when the time of the pump-down operation is shorter than the time threshold value tith, the determination means 34 determines that refrigerant is leaking, and when the time of the pump-down operation is equal to or greater than the time threshold value tith, the determination means 34 determines that refrigerant is not leaking.

Next, the operation of the refrigeration cycle device 200 of the second embodiment will be described with reference to Fig. 5. Of the processes of steps S101 to S109 shown in Fig. 5, the processes other than steps S105, S107, and S108 are the same as those of the first embodiment, and therefore detailed descriptions thereof will be omitted.

In the second embodiment, when the compressor control means 33 starts the compressor 1 in step S105, the determination means 34 causes the timer 35 to start measuring time. When the compressor control means 33 stops the compressor 1 in step S107, the determination means 34 determines the time of the pump-down operation of the compressor 1 by referring to the time measured by the timer 35. In step S108, the determination means 34 determines whether the time of the pump-down operation is shorter than the time threshold value tith.

If the result of the judgment in step S108 is that the time of the pump-down operation is shorter than the time threshold value tith, the judgment means 34 judges that the refrigerant is leaking (step S109). This is because if the time required for the low pressure Lp to reach the reference value Pref and for the pump-down operation to end is shorter than the time threshold value tith required in the absence of refrigerant leakage, it is considered that a refrigerant leak has occurred and the amount of refrigerant in the refrigerant circuit 20 has decreased.

The refrigeration cycle device 200 of the second embodiment determines whether the time of the pump-down operation is shorter than the time threshold value tith, and if the time of the pump-down operation is shorter than the time threshold value tith, determines that the refrigerant is leaking. According to the second embodiment, as in the first embodiment, even if the compressor 1 is stopped, it is possible to accurately detect the refrigerant leakage, and it is possible to take early action against the refrigerant leakage.

Embodiment 3.
In the first and second embodiments, after the compressor 1 is stopped and a state suitable for refrigerant leakage determination is generated, the determination parameter is the high pressure HP in the first embodiment, and the determination parameter is the pump-down operation time in the second embodiment. In the third embodiment, refrigerant leakage is determined based on the degree of subcooling SC. In the third embodiment, the same components as those described in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

The configuration of the refrigeration cycle device of the third embodiment will be described. FIG. 8 is a refrigerant circuit diagram showing an example of the configuration of the refrigeration cycle device of the third embodiment. As shown in FIG. 8, the refrigeration cycle device 200a has a heat source side unit 100a and a load side unit 110.

As shown in FIG. 8, the receiver 5 and the subcooling heat exchanger 6 are connected in that order to the refrigerant piping 21 between the condenser 4 and the flow control valve 10. The receiver 5 temporarily retains the refrigerant flowing out of the condenser 4 and separates the gas-liquid two-phase refrigerant into liquid refrigerant and gas refrigerant. The receiver 5 also serves to recover the refrigerant during pump-down operation. The subcooling heat exchanger 6 puts the refrigerant flowing out of the receiver 5 into a subcooled state.

A refrigerant temperature sensor 7 is provided between the subcooling heat exchanger 6 and the flow rate control valve 10 to detect the temperature of the refrigerant flowing through the refrigerant piping 21. The refrigerant temperature sensor 7 detects the temperature of the liquid refrigerant that flows out of the subcooling heat exchanger 6 and is accompanied by subcooling. The refrigerant temperature sensor 7 is connected to the controller 30 via a signal line (not shown).

Figure 9 is a functional block diagram showing an example of the configuration of the controller shown in Figure 8. The controller 30 of this embodiment 3 has a calculation means 36 in addition to the refrigeration cycle control means 31, valve control means 32, compressor control means 33, determination means 34 and timer 35 shown in Figure 2.

The calculation means 36 calculates the degree of subcooling SC from the temperature difference between the saturated gas temperature calculated from the high pressure Hp and the temperature of the refrigerant detected by the refrigerant temperature sensor 7. The determination means 34 determines whether the degree of subcooling SC calculated by the calculation means 36 is smaller than a predetermined subcooling threshold SCth. When refrigerant is leaking, the amount of refrigerant in the refrigerant circuit 20 decreases and there is no excess refrigerant in the receiver 5, so that the degree of subcooling SC may be smaller than in a normal case where no refrigerant is leaking. Therefore, when the degree of subcooling SC is smaller than the subcooling threshold Scth, the determination means 34 determines that refrigerant is leaking, and when the degree of subcooling SC is equal to or greater than the subcooling threshold Scth, it determines that refrigerant is not leaking.

Next, the operation of the refrigeration cycle device 200a of the third embodiment will be described with reference to Fig. 5. Of the processes of steps S101 to S109 shown in Fig. 5, the processes except for step S108 are the same as those of the first embodiment, and therefore detailed descriptions thereof will be omitted.

In the third embodiment, in step S108, the calculation means 36 calculates the degree of subcooling SC from the temperature difference between the saturated gas temperature calculated from the high pressure Hp and the temperature of the refrigerant detected by the refrigerant temperature sensor 7. The determination means 34 determines whether the degree of subcooling SC calculated by the calculation means 36 is smaller than the subcooling threshold SCth.

If the result of the judgment in step S108 is that the degree of supercooling SC is smaller than the supercooling threshold SCth, the judgment means 34 judges that refrigerant is leaking (step S109). This is because it is considered that the degree of supercooling SC is smaller than the normal supercooling threshold SCth due to the occurrence of refrigerant leakage, the amount of refrigerant in the refrigerant circuit 20 decreasing, and the surplus refrigerant in the receiver 5 disappearing.

The refrigeration cycle device 200a of the third embodiment determines whether the degree of supercooling SC is smaller than the supercooling threshold SCth, and if the degree of supercooling SC is smaller than the supercooling threshold SCth, determines that the refrigerant is leaking. According to the third embodiment, as in the first embodiment, even if the compressor 1 is stopped, it is possible to accurately detect a refrigerant leak and to take early action against the refrigerant leak.

Embodiment 4.
In the first and second embodiments, after the compressor 1 is stopped and a state suitable for refrigerant leakage determination is generated, the first embodiment uses the high pressure HP as the determination parameter, and the second embodiment uses the pump-down operation time as the determination parameter to determine whether or not there is a refrigerant leakage. In the third embodiment, after the compressor 1 is stopped and a state suitable for refrigerant leakage determination is generated, the subcooling degree SC is used as the determination parameter to determine whether or not there is a refrigerant leakage. In the fourth embodiment, a refrigerant leakage is determined based on the temperature of the refrigerant discharged from the compressor 1. In the fourth embodiment, the same components as those described in the first to third embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

The configuration of the refrigeration cycle device of the fourth embodiment will be described. FIG. 10 is a refrigerant circuit diagram showing an example of the configuration of the refrigeration cycle device of the fourth embodiment. As shown in FIG. 10, the refrigeration cycle device 200b has a heat source side unit 100b and a load side unit 110.

As shown in Figure 10, a discharge temperature sensor 2 is provided in the refrigerant piping 21 between the compressor 1 and the condenser 4. The discharge temperature sensor 2 is provided on the refrigerant discharge port side of the compressor 1 and detects the discharge temperature DT, which is the temperature of the refrigerant discharged from the compressor 1.

Figure 11 is a functional block diagram showing an example configuration of the controller shown in Figure 10. The determination means 34 of this embodiment 4 determines whether the discharge temperature DT detected by the discharge temperature sensor 2 is equal to or higher than a predetermined temperature threshold value Teth. When refrigerant is leaking, the amount of refrigerant in the refrigerant circuit 20 is reduced, so the discharge temperature DT of the compressor 1 tends to rise. Therefore, when the discharge temperature DT is equal to or higher than the temperature threshold value Teth, the determination means 34 determines that refrigerant is leaking. When the discharge temperature DT is less than the temperature threshold value Teth, the determination means 34 determines that refrigerant is not leaking.

Next, the operation of the refrigeration cycle device 200b of the fourth embodiment will be described with reference to Fig. 5. Of the processes of steps S101 to S109 shown in Fig. 5, the processes except for step S108 are the same as those of the first embodiment, and therefore detailed descriptions thereof will be omitted.

In the fourth embodiment, in step S108, the determination means 34 determines whether the discharge temperature DT is equal to or higher than the temperature threshold value Teth. If the result of the determination in step S108 is that the discharge temperature DT is equal to or higher than the temperature threshold value Teth, the determination means 34 determines that the refrigerant is leaking (step S109). This is because it is considered that the discharge temperature DT of the compressor 1 is rising due to the occurrence of a refrigerant leak and the reduction in the amount of refrigerant in the refrigerant circuit 20.

The refrigeration cycle device 200b of the fourth embodiment determines whether the discharge temperature DT is equal to or higher than the temperature threshold value Teth, and if the discharge temperature DT is equal to or higher than the temperature threshold value Teth, determines that the refrigerant is leaking. According to the fourth embodiment, as in the first embodiment, even if the compressor 1 is stopped, the refrigerant leakage can be detected with high accuracy, and the refrigerant leakage can be dealt with promptly.

Embodiment 5.
In the first to fourth embodiments, when the flow control valve 10 is opened with the compressor 1 stopped before the compressor 1 performs the pump-down operation, the refrigerant on the high-pressure side moves to the low-pressure side. Therefore, the compressor 1 may perform an operation in which liquid refrigerant is sucked in immediately after starting the pump-down operation. In the fifth embodiment, the operating frequency of the compressor 1 is controlled to prevent the compressor 1 from sucking in liquid refrigerant when performing the pump-down operation. In the fifth embodiment, the same components as those described in the first to fourth embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

The configuration of the refrigeration cycle device of the fifth embodiment will be described. FIG. 12 is a refrigerant circuit diagram showing an example of the configuration of the refrigeration cycle device of the fifth embodiment. As shown in FIG. 12, the refrigeration cycle device 200c has a heat source side unit 100c and a load side unit 110.

As shown in Figure 12, an intake temperature sensor 8 is provided in the refrigerant piping 21 between the compressor 1 and the evaporator 12. The intake temperature sensor 8 is provided on the refrigerant intake side of the compressor 1, and detects the intake temperature ST, which is the temperature of the refrigerant sucked into the compressor 1.

Figure 13 is a functional block diagram showing an example of the configuration of the controller shown in Figure 12. The controller 30 of this embodiment 5 has a calculation means 36 in addition to the refrigeration cycle control means 31, valve control means 32, compressor control means 33, determination means 34, and timer 35 shown in Figure 2.

The calculation means 36 calculates the degree of superheat (suction SH) from the temperature difference between the saturated gas temperature calculated from the low pressure LP and the suction temperature ST detected by the suction temperature sensor 8 during the pump-down operation of the compressor 1. The determination means 34 determines whether the degree of superheat calculated by the calculation means 36 is equal to or less than a predetermined superheat threshold SHth. When the compressor 1 sucks in liquid refrigerant, the degree of superheat of the refrigerant sucked by the compressor 1 becomes small. Therefore, when the degree of superheat calculated by the calculation means 36 is equal to or less than the superheat threshold SHth, the determination means 34 determines that the compressor 1 is sucking in liquid refrigerant. When the determination means 34 determines that the degree of superheat is equal to or less than the superheat threshold SHth, the compressor control means 33 reduces the operating frequency fc of the compressor 1 by a predetermined constant value of frequency Δf from the operating frequency when the pump-down operation is started. In the present embodiment 5, the minimum frequency of the operating frequency fc of the compressor 1 is fcmin.

The operation of the refrigeration cycle apparatus 200b of the fifth embodiment will now be described. FIG. 14 is a flowchart showing the operation procedure of the refrigeration cycle apparatus according to the fifth embodiment. FIG. 14 shows an example of a control method for preventing the compressor 1 from sucking in liquid refrigerant during pump-down operation. During pump-down operation in steps S105 to S106 shown in FIG. 5, the controller 30 controls the compressor 1 in accordance with the procedure shown in FIG. 14.

In step S201, the compressor control means 33 starts the compressor 1. In step S202, the calculation means 36 calculates the degree of superheat (intake SH) from the temperature difference between the saturated gas temperature calculated from the low pressure LP and the intake temperature ST detected by the intake temperature sensor 8. The determination means 34 determines whether the degree of superheat (intake SH) is equal to or lower than the superheat threshold SHth.

When the compressor 1 draws in liquid refrigerant, the degree of superheat of the refrigerant drawn in by the compressor 1 decreases. Therefore, in the judgment process of step S202, if the judgment means 34 judges that the degree of superheat (suction SH) is equal to or lower than the superheat threshold SHth, it judges that the compressor 1 is drawing in liquid refrigerant. In this case, the compressor control means 33 reduces the operating frequency fc of the compressor 1 by the frequency Δf (step S203).

After the processing of step S203, the compressor control means 33 judges whether the operating frequency fc of the compressor 1 is the same as the minimum frequency fcmin (step S204). If the operating frequency fc of the compressor 1 is not the same as the minimum frequency fcmin, the controller 30 returns to step S202. The calculation means 36 calculates the superheating degree again, and the judgment means 34 judges whether the superheating degree is equal to or lower than the superheating threshold value SHth. On the other hand, if the result of the judgment in step S204 is that the operating frequency fc of the compressor 1 is the same as the minimum frequency fcmin, the compressor control means 33 maintains the operating frequency fc at the minimum frequency fcmin during pump-down operation (step S205).

In this way, when the degree of superheat is equal to or lower than the superheat threshold SHth, the compressor control means 33 eventually reduces the operating frequency fc of the compressor 1 until it reaches the minimum frequency fcmin. Therefore, even if the compressor 1 is in a state where it draws in liquid refrigerant during pump-down operation, the operating frequency fc is reduced so as not to draw in the liquid refrigerant, thereby suppressing damage to the compressor 1. Note that the refrigerant leakage determination process by the refrigeration cycle device 200c of this embodiment 5 is the same as the procedure described with reference to FIG. 5, so a detailed description thereof will be omitted. In order to suppress the intake of liquid refrigerant into the compressor 1, this embodiment 5 can be applied to any of the embodiments 1 to 4.

In the refrigeration cycle device 200c of the fifth embodiment, the low pressure Lp is increased while the compressor 1 is stopped, and then the compressor 1 is caused to perform pump-down operation, but the compressor 1 is controlled so that the compressor 1 does not suck in liquid refrigerant based on the degree of superheat. According to the fifth embodiment, it is possible to accurately determine the leakage of refrigerant, as in the first embodiment, while protecting the compressor 1.

Embodiment 6.
In the fifth embodiment, the operating frequency fc of the compressor 1 is controlled based on the degree of superheat in order to prevent the compressor 1 from sucking in liquid refrigerant when the compressor 1 performs pump-down operation. In the sixth embodiment, an accumulator is provided on the refrigerant suction port side of the compressor 1 in order to prevent the compressor 1 from sucking in liquid refrigerant. In the sixth embodiment, the same components as those described in the first to fifth embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

The configuration of the refrigeration cycle device of the sixth embodiment will be described. FIG. 15 is a refrigerant circuit diagram showing an example of the configuration of the refrigeration cycle device according to the sixth embodiment. As shown in FIG. 15, the refrigeration cycle device 200d has a heat source side unit 100d and a load side unit 110d.

As shown in FIG. 15, an accumulator 14 is provided between the evaporator 12 and the compressor 1. The accumulator 14 separates the refrigerant flowing in from the evaporator 12 into liquid refrigerant and gas refrigerant, and flows the gas refrigerant out to the compressor 1.

In the refrigeration cycle apparatus 200c of the fifth embodiment, when the compressor 1 performs pump-down operation, the operating frequency fc is reduced to prevent the compressor 1 from drawing in liquid refrigerant and prevent damage to the compressor 1. However, because the operating frequency fc of the compressor 1 is lower than that in the case of normal pump-down operation, the time from the start to the end of the pump-down operation is longer than normal, and the time until a refrigerant leak is detected is also longer.

In contrast, in the sixth embodiment, as shown in FIG. 15, an accumulator 14 is provided between the evaporator 12 and the compressor 1. By providing the accumulator 14 between the evaporator 12 and the compressor 1, the inflow of liquid refrigerant into the compressor 1 can be suppressed. This suppresses a decrease in the degree of superheat (suction SH) calculated from the temperature difference between the saturated gas temperature calculated from the low pressure LP of the compressor 1 and the suction temperature ST detected by the suction temperature sensor 8. As a result, the compressor control means 33 is suppressed from reducing the operating frequency fc of the compressor 1, and the time from the start to the end of the pump-down operation can be suppressed from becoming longer than usual.

The refrigerant leakage determination process by the refrigeration cycle device 200d of the sixth embodiment is similar to the procedure described with reference to Figure 5, and therefore a detailed description thereof will be omitted. Also, although the sixth embodiment has been described based on the fifth embodiment, it can be applied to any of the first to fourth embodiments and the embodiments described below, with the aim of suppressing the intake of liquid refrigerant into the compressor 1.

In the refrigeration cycle device 200d of the sixth embodiment, the low pressure Lp is increased while the compressor 1 is stopped, and then the compressor 1 is caused to perform pump-down operation, but the accumulator 14 prevents the compressor 1 from drawing in liquid refrigerant. According to the fifth embodiment, the refrigerant leakage can be accurately determined, as in the first embodiment, while preventing the pump-down operation time from becoming long and protecting the compressor 1.

Embodiment 7.
In the seventh embodiment, a fan is provided in the load unit, and the rotation speed of the fan is controlled to prevent the compressor 1 from sucking in liquid refrigerant during pump-down operation. In the seventh embodiment, the same components as those described in the first to sixth embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

The configuration of the refrigeration cycle device of the seventh embodiment will be described. FIG. 16 is a refrigerant circuit diagram showing an example of the configuration of the refrigeration cycle device of the seventh embodiment. As shown in FIG. 16, the refrigeration cycle device 200e has a heat source side unit 100e and a load side unit 110e.

As shown in Fig. 16, the load unit 110e is provided with a fan 13 that supplies air to the evaporator 12. The fan 13 has a fan motor 41 and a propeller 42 connected to the fan motor 41 via a shaft. The fan motor 41 is connected to the controller 30 via a signal line (not shown).

Figure 17 is a functional block diagram showing an example of the configuration of the controller shown in Figure 16. The controller 30 of this embodiment 7 has a fan control means 37 in addition to the multiple means shown in Figure 13. The fan control means 37 controls the rotation speed N of the fan 13. The rotation speed N is the number of rotations per unit time (e.g., one minute).

During pump-down operation of the compressor 1, the calculation means 36 calculates the degree of superheat (suction SH) from the temperature difference between the saturated gas temperature calculated from the low pressure LP and the suction temperature ST detected by the suction temperature sensor 8. The determination means 34 determines whether the degree of superheat calculated by the calculation means 36 is equal to or lower than a predetermined superheat threshold SHth. When the determination means 34 determines that the degree of superheat is equal to or lower than the superheat threshold SHth, the fan control means 37 increases the rotation speed N of the fan 13 by a predetermined constant value of rotation speed ΔN from the rotation speed when the pump-down operation is started. In this embodiment 7, the maximum rotation speed of the rotation speed N of the fan 13 is set to Nmax.

16, when the cooling method of the evaporator 12 provided in the load unit 110e is air-cooled by the fan 13, the evaporation of the liquid refrigerant can be promoted by increasing the rotation speed of the fan 13 to increase the amount of air flowing to the evaporator 12. As a result, the inflow of the liquid refrigerant into the compressor 1 is suppressed, and the decrease in the degree of superheat can be suppressed.

The operation of the refrigeration cycle device 200e of the seventh embodiment will be described with reference to Fig. 14. Of the processes of steps S201 to S205 shown in Fig. 14, the processes of steps S201 to S202 are the same as those of the fifth embodiment, and therefore detailed description thereof will be omitted.

In step S202, if the judgment means 34 judges that the degree of superheat (intake SH) is equal to or less than the superheat threshold SHth, in step S203, the fan control means 37 increases the rotation speed N of the fan 13 by the rotation speed ΔN. In step S204, the fan control means 37 judges whether the rotation speed N of the fan 13 is the same as the maximum rotation speed Nmax. If the rotation speed N of the fan 13 is the same as the maximum rotation speed Nmax, in step S205, the fan control means 37 maintains the rotation speed N at the maximum rotation speed Nmax during pump-down operation.

The refrigerant leakage determination process by the refrigeration cycle device 200e of the seventh embodiment is similar to the procedure described with reference to Figure 5, so a detailed description thereof will be omitted. Also, although the sixth embodiment has been described based on the fifth embodiment, it can be applied to any of the first to fourth embodiments with the aim of suppressing the intake of liquid refrigerant into the compressor 1.

In the refrigeration cycle device 200e of the seventh embodiment, the low pressure Lp is increased while the compressor 1 is stopped, and then the compressor 1 is caused to perform pump-down operation, but the fan 13 provided in the load side unit 110e is controlled so that the compressor 1 does not suck in liquid refrigerant. According to the seventh embodiment, it is possible to accurately determine the leakage of refrigerant, as in the first embodiment, while suppressing the time of the pump-down operation from becoming long and protecting the compressor 1.

Embodiment 8.
The refrigeration cycle device of the eighth embodiment has a plurality of load side units. In the eighth embodiment, the same components as those described in the first to seventh embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

The configuration of the refrigeration cycle device of the eighth embodiment will be described. FIG. 18 is a refrigerant circuit diagram showing one configuration example of the refrigeration cycle device according to the eighth embodiment. As shown in FIG. 18, the refrigeration cycle device 200f has a heat source side unit 100 and a plurality of load side units 110-1 and 110-2. The plurality of load side units 110-1 and 110-2 are connected in parallel to the heat source side unit 100. FIG. 18 shows a case where there are two load side units 110 shown in FIG. 1, but the number of load side units 110 is not limited to two and may be three or more.

The load side unit 110-1 has a flow control valve 10a, a pressure reducing device 11a, an evaporator 12a, a room temperature sensor 23a, and an alarm device 50. The load side unit 110-2 has a flow control valve 10b, a pressure reducing device 11b, an evaporator 12b, and a room temperature sensor 23b. The flow control valves 10a and 10b have the same configuration as the flow control valve 10, the pressure reducing devices 11a and 11b have the same configuration as the pressure reducing device 11, and the evaporators 12a and 12b have the same configuration as the evaporator 12, so detailed descriptions of these will be omitted. The room temperature sensors 23a and 23b have the same configuration as the room temperature sensor 23, so detailed descriptions of them will be omitted. The alarm device 50 may be provided in the load side unit 110-2 instead of the load side unit 110-1, or may be provided in both the load side units 110-1 and 110-2.

As shown in Figure 18, the refrigerant pipe 21 extending from the condenser 4 branches into refrigerant pipes 21a and 21b, and the flow control valve 10a, pressure reduction device 11a, and evaporator 12a of the load side unit 110-1 are connected in sequence via the refrigerant pipe 21a. The flow control valve 10b, pressure reduction device 11b, and evaporator 12b of the load side unit 110-2 are connected in sequence via the refrigerant pipe 21b. The refrigerant pipe 21a extending from the load side unit 110-1 and the refrigerant pipe 21b extending from the load side unit 110-2 join together and are connected to the refrigerant suction port of the compressor 1.

Figure 19 is a functional block diagram showing an example of the configuration of the controller shown in Figure 18. Valve control means 32 controls pressure reducing devices 11a and 11b and flow rate regulating valves 10a and 10b.

Next, the operation of the refrigeration cycle device 200f of the eighth embodiment will be described with reference to Fig. 5. In the fifth embodiment, of steps S101 to S109 shown in Fig. 5, except for step S102, the process is the same as that described with reference to the first and fifth embodiments, and therefore a detailed description thereof will be omitted.

In step S102, the valve control means 32 switches all of the flow control valves 10a provided in the load side unit 110-1 and the flow control valves 10b provided in the load side unit 110-2 that are in a closed state to an open state. This allows refrigerant to flow through the evaporator 12 of the load side unit 110, through which refrigerant had not been flowing.

When the flow control valve 10 opens and the liquid refrigerant on the high pressure side moves to the low pressure side, the liquid refrigerant can be evaporated by the evaporators 12 of all the load side units 110, rather than evaporating the liquid refrigerant only by the evaporators 12 of the load side units 110 that were operating before the compressor 1 was stopped. This makes it possible to suppress the inflow of liquid refrigerant into the compressor 1, and suppress a decrease in the degree of superheat (suction SH).

Although the present embodiment 8 has been described based on the embodiment 5, it can also be applied to any of the embodiments 1 to 4 with the aim of suppressing the suction of liquid refrigerant into the compressor 1.

In the refrigeration cycle device 200f of the eighth embodiment, the low pressure Lp is increased while the compressor 1 is stopped, and then the compressor 1 is caused to perform pump-down operation, but all of the flow control valves 10 provided in the multiple load side units 110 are opened. According to the eighth embodiment, it is possible to accurately determine the leakage of refrigerant, as in the first embodiment, while preventing the pump-down operation time from becoming long and protecting the compressor 1.

In the above-mentioned embodiments 1 to 8, the load-side heat exchanger provided in the load-side unit 110 has been described as functioning as the evaporator 12, but the load-side heat exchanger may also function as the condenser 4. Also, a four-way valve for switching the refrigerant flow direction in the refrigerant circuit 20 may be provided in the heat source unit 100 so that the operation mode of the load-side unit 110 can be switched between cooling operation and heating operation. In this case, the load-side heat exchanger functions as the evaporator 12 or the condenser 4 depending on the operation mode of the load-side unit 110.

The refrigeration cycle devices 200 to 200f described with reference to the first to eighth embodiments can be applied to refrigerant leakage determination when the compressor 1 is stopped for a long period of time. Two or more of the first to eighth embodiments described above may be combined so as not to cause mutual contradictions.

1 Compressor, 2 Discharge temperature sensor, 3 High pressure sensor, 4 Condenser, 5 Receiver, 6 Subcooling heat exchanger, 7 Refrigerant temperature sensor, 8 Suction temperature sensor, 9 Low pressure sensor, 10, 10a, 10b Flow control valve, 11, 11a, 11b Pressure reducing device, 12, 12a, 12b Evaporator, 13 Fan, 14 Accumulator, 20 Refrigerant circuit, 21, 21a, 21b Refrigerant piping, 23, 23a, 23b Room temperature sensor, 25 Signal line, 30 Controller, 31 Refrigeration cycle control means, 32 Valve control means, 33 Compressor control means, 34 Determination means, 35 Timer, 36 Calculation means, 37 Fan control means, 41 Fan motor, 42 Propeller, 50 Notification device, 90 Processing circuit, 91 Processor, 92 Memory, 93 Bus, 100, 100a to 100e heat source side units, 110, 110-1, 110-2, 110d, 110e load side units, 200, 200a to 200f refrigeration cycle devices.

Claims (14)

a refrigerant circuit in which a compressor, a condenser, and an evaporator are connected by a refrigerant pipe, and a refrigerant circulates through the refrigerant pipe;
a low pressure sensor provided between the compressor and the evaporator for detecting a low pressure, which is a pressure of the refrigerant flowing through the refrigerant pipe;
a flow rate control valve provided between the condenser and the evaporator;
a controller for controlling the compressor and the flow rate control valve,
The controller:
a valve control means for switching the flow control valve from the open state to a closed state after keeping the flow control valve in an open state until the elapsed time from when the compressor was stopped is equal to or longer than a reference time for ensuring a certain operating time of the compressor in a pump-down operation;
a compressor control means for causing the compressor to execute the pump-down operation in which the refrigerant in the refrigerant circuit is recovered in the condenser when the flow rate control valve is switched from the open state to the closed state;
a determination unit that determines whether or not the refrigerant is leaking based on a state of a device constituting the refrigerant circuit or the state of the refrigerant when the compressor finishes the pump-down operation;
A refrigeration cycle device having the above structure. a refrigerant circuit in which a compressor, a condenser, and an evaporator are connected by a refrigerant pipe, and a refrigerant circulates through the refrigerant pipe;
a low pressure sensor provided between the compressor and the evaporator for detecting a low pressure, which is a pressure of the refrigerant flowing through the refrigerant pipe;
a flow rate control valve provided between the condenser and the evaporator;
a controller for controlling the compressor and the flow rate control valve,
The controller:
a valve control means for opening the flow control valve until the low pressure becomes equal to or higher than a reference value for ensuring a certain period of operation of the compressor in a pump-down operation while the compressor is stopped, and then switching the flow control valve from the open state to a closed state;
a compressor control means for causing the compressor to execute the pump-down operation in which the refrigerant in the refrigerant circuit is recovered in the condenser when the flow rate control valve is switched from the open state to the closed state;
a determination unit that determines whether or not the refrigerant is leaking based on a state of a device constituting the refrigerant circuit or the state of the refrigerant when the compressor finishes the pump-down operation;
A refrigeration cycle device having the above structure. The determination means is
If the time of the pump-down operation is shorter than a predetermined time threshold, it is determined that the refrigerant is leaking.
The refrigeration cycle device according to claim 1 or 2. a high-pressure sensor provided between the compressor and the condenser for detecting a high-pressure pressure of the refrigerant flowing through the refrigerant pipe;
The determination means is
If the high pressure is equal to or lower than a predetermined pressure threshold, it is determined that the refrigerant is leaking.
The refrigeration cycle device according to claim 1 or 2. a receiver provided between the condenser and the flow rate control valve;
a subcooling heat exchanger provided between the receiver and the flow rate control valve;
a high-pressure sensor provided between the compressor and the condenser and configured to detect a high-pressure pressure of the refrigerant flowing through the refrigerant pipe;
a refrigerant temperature sensor provided between the subcooling heat exchanger and the flow rate regulating valve for detecting a temperature of the refrigerant flowing out from the subcooling heat exchanger;
The controller:
a calculation means for calculating a degree of subcooling from a temperature difference between a saturated gas temperature calculated from the high pressure and a temperature of the refrigerant detected by the refrigerant temperature sensor;
The determination means is
When the degree of subcooling calculated by the calculation means is smaller than a predetermined subcooling threshold value, it is determined that the refrigerant is leaking.
The refrigeration cycle device according to claim 1 or 2. a discharge temperature sensor provided between the compressor and the condenser for detecting a discharge temperature of the refrigerant discharged from the compressor;
The determination means is
When the discharge temperature detected by the discharge temperature sensor is equal to or higher than a predetermined temperature threshold, it is determined that the refrigerant is leaking.
The refrigeration cycle device according to claim 1 or 2. a refrigerant circuit in which a compressor, a condenser, and an evaporator are connected by a refrigerant pipe, and a refrigerant circulates through the refrigerant pipe;
a low pressure sensor provided between the compressor and the evaporator for detecting a low pressure, which is a pressure of the refrigerant flowing through the refrigerant pipe;
an intake temperature sensor provided between the compressor and the evaporator for detecting an intake temperature, which is a temperature of a refrigerant sucked into the compressor ;
a flow rate control valve provided between the condenser and the evaporator;
a controller for controlling the compressor and the flow rate control valve,
The controller:
a valve control means for switching the flow rate control valve from the open state to a closed state after the flow rate control valve is kept in an open state until the elapsed time from when the compressor was stopped becomes equal to or longer than a predetermined reference time;
a compressor control means for causing the compressor to perform a pump-down operation in which the refrigerant in the refrigerant circuit is recovered in the condenser when the flow rate control valve is switched from the open state to the closed state;
a determination unit that determines whether or not the refrigerant is leaking based on a state of a device constituting the refrigerant circuit or the state of the refrigerant when the compressor finishes the pump-down operation;
a calculation means for calculating a degree of superheat from a temperature difference between a saturated gas temperature calculated from the low pressure and the intake temperature detected by the intake temperature sensor during the pump-down operation,
The determination means is
Determining whether the degree of superheat calculated by the calculation means is equal to or less than a predetermined superheat threshold value;
The compressor control means
When the determination means determines that the degree of superheat is equal to or lower than the superheat threshold value, an operation frequency of the compressor is made lower than an operation frequency at the start of the pump-down operation. a refrigerant circuit in which a compressor, a condenser, and an evaporator are connected by a refrigerant pipe, and a refrigerant circulates through the refrigerant pipe;
a low pressure sensor provided between the compressor and the evaporator for detecting a low pressure, which is a pressure of the refrigerant flowing through the refrigerant pipe;
an intake temperature sensor provided between the compressor and the evaporator for detecting an intake temperature, which is a temperature of a refrigerant sucked into the compressor;
a flow rate control valve provided between the condenser and the evaporator;
a controller for controlling the compressor and the flow rate control valve,
The controller:
a valve control means for opening the flow control valve until the low pressure reaches a predetermined reference value or more while the compressor is stopped, and then switching the flow control valve from the open state to a closed state;
a compressor control means for causing the compressor to perform a pump-down operation in which the refrigerant in the refrigerant circuit is recovered in the condenser when the flow rate control valve is switched from the open state to the closed state;
a determination unit that determines whether or not the refrigerant is leaking based on a state of a device constituting the refrigerant circuit or the state of the refrigerant when the compressor finishes the pump-down operation;
a calculation means for calculating a degree of superheat from a temperature difference between a saturated gas temperature calculated from the low pressure and the intake temperature detected by the intake temperature sensor during the pump-down operation,
The determination means is
Determining whether the degree of superheat calculated by the calculation means is equal to or less than a predetermined superheat threshold value;
The compressor control means
When the determination means determines that the degree of superheat is equal to or lower than the superheat threshold value, an operation frequency of the compressor is made lower than an operation frequency at the start of the pump-down operation. a refrigerant circuit in which a compressor, a condenser, and an evaporator are connected by a refrigerant pipe, and a refrigerant circulates through the refrigerant pipe;
a low pressure sensor provided between the compressor and the evaporator for detecting a low pressure, which is a pressure of the refrigerant flowing through the refrigerant pipe;
A fan for supplying air to the evaporator;
an intake temperature sensor provided between the compressor and the evaporator for detecting an intake temperature, which is a temperature of a refrigerant sucked into the compressor;
a flow rate control valve provided between the condenser and the evaporator;
a controller for controlling the compressor and the flow rate control valve ,
The controller:
a valve control means for switching the flow rate control valve from the open state to a closed state after the flow rate control valve is kept in an open state until the elapsed time from when the compressor was stopped becomes equal to or longer than a predetermined reference time;
a compressor control means for causing the compressor to perform a pump-down operation in which the refrigerant in the refrigerant circuit is recovered in the condenser when the flow rate control valve is switched from the open state to the closed state;
a determination unit that determines whether or not the refrigerant is leaking based on a state of a device constituting the refrigerant circuit or the state of the refrigerant when the compressor finishes the pump-down operation;
a calculation means for calculating a degree of superheat from a temperature difference between a saturated gas temperature calculated from the low pressure and the suction temperature detected by the suction temperature sensor during the pump-down operation;
A fan control means for controlling the rotation speed of the fan,
The determination means is
Determining whether the degree of superheat calculated by the calculation means is equal to or less than a predetermined superheat threshold value;
The fan control means
When the determining means determines that the degree of superheat is equal to or lower than the superheat threshold value, the rotation speed of the fan is increased above the rotation speed at the start of the pump-down operation. a refrigerant circuit in which a compressor, a condenser, and an evaporator are connected by a refrigerant pipe, and a refrigerant circulates through the refrigerant pipe;
a low pressure sensor provided between the compressor and the evaporator for detecting a low pressure, which is a pressure of the refrigerant flowing through the refrigerant pipe;
A fan for supplying air to the evaporator;
an intake temperature sensor provided between the compressor and the evaporator for detecting an intake temperature, which is a temperature of a refrigerant sucked into the compressor;
a flow rate control valve provided between the condenser and the evaporator;
a controller for controlling the compressor and the flow rate control valve,
The controller:
a valve control means for opening the flow control valve until the low pressure reaches a predetermined reference value or more while the compressor is stopped, and then switching the flow control valve from the open state to a closed state;
a compressor control means for causing the compressor to perform a pump-down operation in which the refrigerant in the refrigerant circuit is recovered in the condenser when the flow rate control valve is switched from the open state to the closed state;
a determination unit that determines whether or not the refrigerant is leaking based on a state of a device constituting the refrigerant circuit or the state of the refrigerant when the compressor finishes the pump-down operation;
a calculation means for calculating a degree of superheat from a temperature difference between a saturated gas temperature calculated from the low pressure and the suction temperature detected by the suction temperature sensor during the pump-down operation;
A fan control means for controlling the rotation speed of the fan,
The determination means is
Determining whether the degree of superheat calculated by the calculation means is equal to or less than a predetermined superheat threshold value;
The fan control means
When the determining means determines that the degree of superheat is equal to or lower than the superheat threshold value, the rotation speed of the fan is increased above the rotation speed at the start of the pump-down operation. The cooling system further includes an accumulator disposed between the evaporator and the compressor.
The refrigeration cycle device according to any one of claims 1 to 10 . The refrigerant circuit includes a plurality of load-side units each including the condenser or the evaporator and the flow rate control valve,
The valve control means
when switching the flow rate control valves from the open state to the closed state, all of the flow rate control valves provided in each of the plurality of load side units that are in the closed state are switched to the open state.
The refrigeration cycle device according to any one of claims 1 to 6. The flow rate regulating valve is a pressure reducing device that reduces the pressure of the refrigerant to expand it.
The refrigeration cycle device according to any one of claims 1 to 12 . a pressure reducing device provided between the condenser and the evaporator in the refrigerant circuit,
The flow rate control valve is provided between the condenser and the pressure reducing device.
The refrigeration cycle device according to any one of claims 1 to 12 .

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