WO2023199511A1

WO2023199511A1 - Refrigeration cycle device

Info

Publication number: WO2023199511A1
Application number: PCT/JP2022/017918
Authority: WO
Inventors: 洋貴佐藤; 裕士佐多; 智隆石川
Original assignee: 三菱電機株式会社
Priority date: 2022-04-15
Filing date: 2022-04-15
Publication date: 2023-10-19

Abstract

This refrigeration cycle device comprises: a refrigerant circuit in which a compressor, a condenser, and an evaporator are connected by a refrigerant piping and through which a refrigerant flows; a first electromagnetic valve which is disposed between the condenser and the evaporator in the refrigerant piping and which has a function of switching between an open state where the refrigerant flowing through the refrigerant circuit is allowed to pass therethrough and a close state where the refrigerant flowing through the refrigerant circuit is blocked; a first bypass piping which has one end connected to a portion between the condenser and the first electromagnetic valve in the refrigerant piping and has the other end connected to a portion between the evaporator and the compressor in the refrigerant piping; a receiver which is provided to the first bypass piping and which stores therein the refrigerant; a second electromagnetic valve which is disposed between the one end of the first bypass piping and the receiver in the first bypass piping and which has a function of switching between an open state where the refrigerant flowing to the receiver is allowed to pass therethrough and a close state where the refrigerant flowing to the receiver is blocked; a third electromagnetic valve that is disposed between the receiver and the other end of the first bypass piping in the first bypass piping and has a function of switching between an open state where the refrigerant flowing from the receiver is allowed to pass therethough and a close state where the refrigerant flowing from the receiver is blocked; and a control device that controls the compressor, the first electromagnetic valve, the second electromagnetic valve, and the third electromagnetic valve. The control device executes: a normal operation in which the compressor is driven while the first electromagnetic valve is kept in the open state whereas the second electromagnetic valve is kept in the close state; and a pump down operation in which the compressor is driven while the second electromagnetic valve is kept in the open state whereas the first electromagnetic valve and the third electromagnetic valve are kept in the close state.

Description

Refrigeration cycle equipment

The present disclosure relates to a refrigeration cycle device having a receiver.

Conventionally, refrigeration cycle devices having a receiver for storing refrigerant are known. Refrigerant is stored in a receiver of a refrigeration cycle device during pump-down operation performed during maintenance work, for example. Patent Document 1 discloses such a refrigeration cycle device that detects the amount of refrigerant leaking from a refrigerant circuit by storing refrigerant in a receiver.

Japanese Patent Application Publication No. 2014-095514

There are limits to the amount of refrigerant that can be sealed in a refrigeration cycle device depending on the type of refrigerant. However, in a refrigeration cycle device having a receiver as disclosed in Patent Document 1, some refrigerant remains in the receiver during operation. Most of the refrigerant that stays in the receiver is gas refrigerant, but for models of refrigeration cycle devices with high horsepower, the volume of the receiver becomes large, and the amount of gas refrigerant that stays in the receiver also increases. Therefore, in a refrigeration cycle device having a receiver, it is sometimes difficult to reduce the amount of refrigerant enclosed and satisfy the restrictions.

The present disclosure has been made to solve the above problems, and aims to reduce the amount of refrigerant sealed in a refrigeration cycle device having a receiver.

A refrigeration cycle device according to the present disclosure is provided with a refrigerant circuit in which a compressor, a condenser, and an evaporator are connected by refrigerant piping, through which the refrigerant flows, and a refrigerant circuit that is provided between the condenser and the evaporator in the refrigerant piping. A first solenoid valve having a function of switching between an open state that allows flowing refrigerant to pass through and a closed state that blocks refrigerant flowing through the refrigerant circuit, and one end of which is connected to a portion of the refrigerant piping between the condenser and the first solenoid valve. , a first bypass pipe whose other end connects to a portion of the refrigerant pipe between the evaporator and the compressor; a receiver provided in the first bypass pipe to store refrigerant; A second electromagnetic valve is provided between one end of the pipe and the receiver and has a function of switching between an open state that allows refrigerant flowing to the receiver to pass and a closed state that blocks refrigerant flowing to the receiver, and the first bypass pipe, a third solenoid valve that is provided between the receiver and the other end of the first bypass pipe and has a function of switching between an open state that allows refrigerant flowing from the receiver to pass through and a closed state that blocks refrigerant that flows from the receiver; , a control device that controls the first solenoid valve, the second solenoid valve, and the third solenoid valve, the control device maintains the first solenoid valve in an open state and maintains the second solenoid valve in a closed state. a normal operation in which the compressor is driven; and a pump-down operation in which the compressor is driven by maintaining the second solenoid valve in an open state and maintaining the first and third solenoid valves in a closed state. A refrigeration cycle device that runs

In normal operation, the refrigeration cycle device of the present disclosure maintains the first solenoid valve in an open state, maintains the second solenoid valve in a closed state, and drives the compressor. Further, in the pump down operation, the second solenoid valve is maintained in an open state, the first solenoid valve and the third solenoid valve are maintained in a closed state, and the compressor is driven. Here, in the refrigeration cycle device of the present disclosure, a receiver that stores refrigerant is provided in the first bypass pipe. Therefore, the amount of refrigerant that stays in the receiver during normal operation is smaller than the amount of refrigerant that stays in the receiver when the receiver is provided in series in the refrigerant circuit. Therefore, in a refrigeration cycle device having a receiver, the amount of refrigerant sealed can be reduced.

1 is a circuit diagram showing a refrigeration cycle device according to Embodiment 1. FIG. 1 is a functional block diagram showing a refrigeration cycle device according to Embodiment 1. FIG. FIG. 3 is a diagram for explaining control details of the control device according to the first embodiment. 1 is a hardware configuration diagram showing one configuration of a control device according to Embodiment 1. FIG. 1 is a hardware configuration diagram showing one configuration of a control device according to Embodiment 1. FIG. 3 is a flowchart showing the operation of the control device according to the first embodiment. FIG. 7 is a diagram for explaining the piping length and horsepower that allow use of a flammable refrigerant in a refrigeration cycle device according to a comparative example. FIG. 2 is a diagram for explaining the piping length and horsepower that allow use of a flammable refrigerant in the refrigeration cycle device according to the first embodiment. FIG. 2 is a circuit diagram showing a refrigeration cycle device according to a second embodiment. FIG. 3 is a circuit diagram showing a refrigeration cycle device according to a third embodiment. FIG. 7 is a diagram for explaining control details of a control device according to a third embodiment. 7 is a flowchart showing the operation of the control device according to Embodiment 3. It is a circuit diagram showing a refrigeration cycle device concerning Embodiment 4. It is a circuit diagram showing a refrigeration cycle device concerning Embodiment 5. FIG. 3 is a circuit diagram showing a refrigeration cycle device according to a modification of the first embodiment.

Embodiment 1.
Hereinafter, a refrigeration cycle device 1 according to Embodiment 1 will be described with reference to the drawings. FIG. 1 is a circuit diagram showing a refrigeration cycle device 1 according to the first embodiment. The refrigeration cycle device 1 is, for example, a refrigeration device that cools air in a target space. As shown in FIG. 1, the refrigeration cycle device 1 includes a heat source device 2, a load device 3, and a control device 90. The heat source device 2 is a device that supplies cold heat to the load device 3. The load device 3 is a device that cools the air in the target space through heat exchange between the air in the target space and a refrigerant. In the first embodiment, for example, a flammable refrigerant is used as the refrigerant. Note that the term "flammable refrigerant" as used herein includes mildly flammable refrigerants. The heat source device 2 and the load device 3 are connected by a connecting pipe 23 and a connecting pipe 24. The control device 90 controls each device of the refrigeration cycle device 1. The detailed configuration of the control device 90 will be described later.

The heat source device 2 includes a compressor 11, a condenser 12, an accumulator 15, and a heat source side piping 21. The heat source side piping 21 is a piping provided inside the heat source device 2. Both ends of the heat source side pipe 21 are connected to a connecting pipe 23 and a connecting pipe 24. The heat source side piping 21 connects the accumulator 15, the compressor 11, and the condenser 12 in this order from the end on the connection piping 24 side. The compressor 11 takes in refrigerant at low temperature and low pressure, compresses the sucked refrigerant, converts it into refrigerant at high temperature and high pressure, and discharges the refrigerant. The condenser 12 performs heat exchange between the refrigerant and air, and condenses the refrigerant. The accumulator 15 is a container that separates the refrigerant into gas and liquid and stores the liquid refrigerant.

The load device 3 includes a first electromagnetic valve 51, an expansion valve 13, an evaporator 14, and a load-side pipe 22. Both ends of the load-side pipe 22 are connected to a connecting pipe 23 and a connecting pipe 24. The load-side pipe 22 connects the first electromagnetic valve 51, the expansion valve 13, and the evaporator 14 in this order from the end on the connection pipe 23 side. The first electromagnetic valve 51 is located between the condenser 12 and the evaporator 14 and has a function of switching between an open state that allows refrigerant flowing through the refrigerant circuit to pass, and a closed state that blocks refrigerant flowing through the refrigerant circuit. In the first embodiment, the expansion valve 13 is provided upstream of the evaporator 14, and the first electromagnetic valve 51 is provided between the condenser 12 and the expansion valve 13. The expansion valve 13 reduces the pressure of the refrigerant and expands it, and is, for example, an electronic expansion valve. The evaporator 14 performs heat exchange between the refrigerant and air to evaporate the refrigerant.

Compressor 11, condenser 12, first electromagnetic valve 51, expansion valve 13, condenser 12, and accumulator 15 are connected by heat source side piping 21, load side piping 22, and connecting piping 23 and connecting piping 24. A refrigerant circuit is constructed. Hereinafter, the heat source side piping 21, the load side piping 22, the connection piping 23, and the connection piping 24 may be collectively referred to as refrigerant piping. That is, the first electromagnetic valve is provided between the condenser 12 and the expansion valve 13 in the refrigerant pipe.

The heat source device 2 also includes a first bypass pipe 31, a second bypass pipe 32, a receiver 41, a capillary tube 42, a second solenoid valve 52, a third solenoid valve 53, and a fourth solenoid valve 54. The first bypass pipe 31 connects a portion of the heat source side pipe 21 on the downstream side of the condenser 12 and a portion on the upstream side of the accumulator 15. In other words, the first bypass pipe 31 has one end connected to the refrigerant pipe between the condenser 12 and the first electromagnetic valve 51, and the other end connected to the refrigerant pipe between the evaporator 14 and the compressor 11. Connect to parts. In the first embodiment, the accumulator 15 is provided on the refrigerant suction side of the compressor 11, and the other end of the first bypass pipe 31 is connected between the evaporator 14 and the accumulator 15. The second bypass pipe 32 connects the receiver 41 and a portion of the first bypass pipe 31 between the second electromagnetic valve 52 and the other end of the first bypass pipe 31 . The second bypass pipe 32 functions as a gas vent pipe that releases excess gaseous refrigerant within the receiver 41 to the outside of the receiver 41 .

The receiver 41 is provided in the first bypass pipe 31 and stores refrigerant. The receiver 41 is a container in which refrigerant is stored during pump-down operation. The capillary tube 42 is a tube that expands the refrigerant passing through it. The second solenoid valve 52 is provided in the first bypass pipe 31 between one end of the first bypass pipe 31 and the receiver 41, and is in an open state to allow the refrigerant flowing to the receiver 41 to pass, and to be in an open state to allow the refrigerant flowing to the receiver 41 to pass. It has a function to switch between the closed state and the shutoff state. The third solenoid valve 53 is provided in the first bypass pipe 31 between the receiver 41 and the other end of the first bypass pipe 31 . The third electromagnetic valve 53 has a function of switching between an open state that allows the refrigerant flowing from the receiver 41 to pass through, and a closed state that blocks the refrigerant that flows from the receiver 41. The fourth electromagnetic valve 54 is provided in a portion of the second bypass piping 32 between the capillary tube 42 and the connection portion with the first bypass piping 31 . The fourth electromagnetic valve 54 has a function of switching between an open state that allows the refrigerant flowing through the second bypass pipe 32 to pass, and a closed state that blocks the refrigerant that flows through the second bypass pipe 32.

FIG. 2 is a functional block diagram showing the refrigeration cycle device 1 according to the first embodiment. As shown in FIG. 2, the control device 90 controls the drive frequency of the compressor 11 of the refrigeration cycle device 1, the opening degree of the expansion valve 13, the first solenoid valve 51, the second solenoid valve 52, the third solenoid valve 53, and controls the opening/closing state of the fourth solenoid valve 54.

FIG. 3 is a diagram for explaining the control content of the control device 90 according to the first embodiment. The control device 90 executes normal operation and pump down operation. Normal operation is an operating method in which the refrigerant circulates through the refrigerant circuit and cools the air in the target space. As shown in FIG. 3, during normal operation, the first solenoid valve 51, the third solenoid valve 53, and the fourth solenoid valve 54 are maintained in the open state, and the second solenoid valve 52 is maintained in the closed state to compress the The machine 11 is driven.

Pump-down operation is an operating method in which the refrigerant does not circulate through the refrigerant circuit, and the refrigerant on the so-called low-pressure side of the refrigeration cycle device 1, from the expansion valve 13 to the compressor 11, is recovered to the receiver 41. Pump-down operation is switched from normal operation and executed when pump-down start conditions are met. Further, the pump-down operation ends when the pump-down end condition is satisfied. When the pump-down operation ends, normal operation resumes. The pump-down start condition is, for example, that the user provides the control device 90 with a signal through an operation panel (not shown) instructing execution of the pump-down operation. The operation panel is an example of a device for receiving input of operation details of the refrigeration cycle device 1 by a user. The pump-down end condition is, for example, that a predetermined period of time has elapsed since the start of the pump-down operation. Alternatively, the condition for ending the pump down may be that a liquid level sensor (not shown) provided in the receiver 41 detects that a predetermined amount of refrigerant has accumulated in the receiver 41. Furthermore, the condition for ending pump-down may be that the pressure detected by a pressure sensor (not shown) provided on the low-pressure side of the refrigeration cycle device 1 becomes a predetermined value or less. In the pump-down operation, the second solenoid valve 52 and the fourth solenoid valve 54 are kept open, the first solenoid valve 51 and the third solenoid valve 53 are kept closed, and the compressor 11 is driven.

Further, when the operation of the refrigeration cycle device 1 is stopped, the control device 90 maintains the second solenoid valve 52 in an open state and closes the first solenoid valve 51, the third solenoid valve 53, and the fourth solenoid valve 54. The drive of the compressor 11 is stopped.

Here, an example of the hardware of the control device 90 will be explained. FIG. 4 is a hardware configuration diagram showing one configuration of the control device 90 according to the first embodiment. When the various functions of the control device 90 are executed by hardware, the control device 90 is configured with a processing circuit 91, as shown in FIG. Each function of the control device 90 is realized by a processing circuit 91.

When each function is executed by hardware, the processing circuit 91 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate). Array) or a combination of these.

Also, another example of hardware of the control device 90 will be explained. FIG. 5 is a hardware configuration diagram showing one configuration of the control device 90 according to the first embodiment. When various functions of the control device 90 are executed by software, the control device 90 is configured with a processor 92 such as a CPU and a memory 93, as shown in FIG. Each function of the control device 90 is realized by a processor 92 and a memory 93. FIG. 5 shows that processor 92 and memory 93 are communicatively connected to each other via bus 94.

When each function is executed by software, the functions of the control device 90 are realized by software, firmware, or a combination of software and firmware. Software and firmware are written as programs and stored in memory 93. The processor 92 realizes the functions of each means by reading and executing programs stored in the memory 93.

Examples of the memory 93 include ROM (Read Only Memory), flash memory, EPROM (Erasable and Programmable ROM), and EEPROM (Electrically Erasable and Programmable ROM). A nonvolatile semiconductor memory such as a programmable ROM (ROM) is used. Further, as the memory 93, a volatile semiconductor memory such as RAM (Random Access Memory) may be used. Further, as the memory 93, 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.

The operation of the refrigeration cycle device 1 will be explained. First, normal operation will be explained. The refrigerant sucked into the compressor 11 is compressed by the compressor 11 and discharged in a high temperature and high pressure gas state. The high temperature and high pressure gaseous refrigerant discharged from the compressor 11 flows into the condenser 12 . The refrigerant flowing into the condenser 12 exchanges heat with air, condenses, and liquefies. The liquid refrigerant passes through the first electromagnetic valve 51 and flows into the expansion valve 13, where it is depressurized and expanded to become a low-temperature, low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant flows into the evaporator 14 . The refrigerant flowing into the evaporator 14 exchanges heat with the air, evaporates, and gasifies. At that time, the air in the target space is cooled. Thereafter, the evaporated low-temperature, low-pressure gaseous refrigerant passes through the accumulator 15 and is sucked into the compressor 11.

Next, pump down operation will be explained. The refrigerant sucked into the compressor 11 is compressed by the compressor 11 and discharged in a high temperature and high pressure gas state. The high temperature and high pressure gaseous refrigerant discharged from the compressor 11 passes through the condenser 12 and the second electromagnetic valve 52 and is stored in the receiver 41 . The gaseous refrigerant stored in the receiver 41 is condensed by the supercooled liquid refrigerant stored in the receiver 41 . A portion of the gaseous refrigerant stored in the receiver 41 flows into the second bypass pipe 32, passes through the capillary tube 42, and expands. The refrigerant expanded after passing through the capillary tube 42 passes through the fourth electromagnetic valve 54 and flows into the first bypass pipe 31 . The refrigerant flowing through the first bypass pipe 31 passes through the accumulator 15 and is sucked into the compressor 11. As the refrigerant circulates through the flow path, the amount of refrigerant stored in the receiver 41 in a liquid state increases. In particular, the second bypass pipe 32 causes excess gas refrigerant in the receiver 41 to escape to the outside of the receiver 41, thereby promoting cooling and condensation of the gas refrigerant in the receiver 41.

The operation of the control device 90 will be explained using a flowchart. FIG. 6 is a flowchart showing the operation of the control device 90 according to the first embodiment. First, during normal operation, when a pump-down start condition is satisfied, the control device 90 starts pump-down operation (step S1). Here, the compressor 11 is driven by maintaining the second solenoid valve 52 and the fourth solenoid valve 54 in the open state, and maintaining the first solenoid valve 51 and the third solenoid valve 53 in the closed state.

Then, the control device 90 determines whether the pump-down end condition is satisfied during the pump-down operation (step S2). If the pump-down end condition is not satisfied (step S2: NO), the process of step S2 is periodically repeated until the pump-down end condition is satisfied. When the pump-down end condition is satisfied (step S2: YES), the control device 90 ends the pump-down operation and starts normal operation (step S3). Here, the first solenoid valve 51, the third solenoid valve 53, and the fourth solenoid valve 54 are maintained in an open state, the second solenoid valve 52 is maintained in a closed state, and the compressor 11 is driven.

As described above, during normal operation, the refrigeration cycle device 1 of the first embodiment maintains the first solenoid valve 51 and the third solenoid valve 53 in the open state, and maintains the second solenoid valve 52 in the closed state. , drives the compressor 11. Further, in the pump down operation, the second solenoid valve 52 is maintained in the open state, the first solenoid valve 51 and the third solenoid valve 53 are maintained in the closed state, and the compressor 11 is driven. Here, in the refrigeration cycle device 1 of the first embodiment, the receiver 41 for storing refrigerant is provided in the first bypass pipe 31. Therefore, the amount of refrigerant that stays in the receiver 41 during normal operation is smaller than the amount of refrigerant that stays in the receiver 41 when the receiver 41 is provided in series in the refrigerant circuit. Therefore, in the refrigeration cycle device 1 having the receiver 41, the amount of refrigerant sealed can be reduced.

Furthermore, according to the first embodiment, since the inside of the receiver 41 becomes a low-pressure space during normal operation, the refrigerant density can be reduced, and the required amount of refrigerant to be filled can be further reduced.

Furthermore, at present, HFC-based refrigerants such as R410A or R404A are mainstream as refrigerants used when operating the refrigeration cycle device 1. Although R410A or R404A has a large global warming potential (GWP) value, it has relatively high stability and nonflammability. However, due to increasing environmental awareness, there is a demand for the refrigeration cycle device 1 to shift to a refrigerant with a smaller GWP value. However, many refrigerants with small GWP values are flammable. If a flammable refrigerant leaks from the piping of the refrigeration cycle device 1 and stagnates in a space outside the refrigerant circuit, it may lead to ignition due to sparks, static electricity, or the like.

From the viewpoint of the above-mentioned flammable refrigerant, further effects of the present application will be explained using a comparative example. FIG. 7 is a diagram for explaining the pipe length and horsepower (HP) in which a flammable refrigerant can be used in a refrigeration cycle device according to a comparative example. The comparative example includes a refrigerant circuit including a compressor 11, a condenser 12, a first electromagnetic valve 51, an expansion valve 13, an evaporator 14, and an accumulator 15. However, the comparative example does not have the first bypass piping 31, the second bypass piping 32, the capillary tube 42, the second solenoid valve 52, the third solenoid valve 53, and the fourth solenoid valve 54 of the first embodiment. . Further, in the comparative example, the receiver is provided as an element of the refrigerant circuit. In order to suppress ignition when a refrigerant leaks, restrictions are imposed so that flammable refrigerants cannot be used when a large amount of refrigerant is used, such as in a refrigeration cycle device with long pipe length or large horsepower. In the comparative example, as shown by the "x" mark in FIG. 7, if the piping length or horsepower of the refrigeration cycle device 1 is greater than a predetermined value and a large amount of refrigerant is used, a flammable refrigerant is used. I can't.

FIG. 8 is a diagram for explaining the pipe length and horsepower (HP) in which a flammable refrigerant can be used in the refrigeration cycle device 1 according to the first embodiment. In contrast to the comparative example, in the refrigeration cycle device 1 of the first embodiment, a receiver 41 for storing refrigerant is provided in the first bypass pipe 31. Therefore, the amount of refrigerant that stays in the receiver 41 during normal operation is small compared to the amount of refrigerant that stays in the receiver 41 when the receiver 41 is provided in series in the refrigerant circuit, and the amount of refrigerant in the refrigeration cycle device 1 is small. Enclosing amount can be reduced. Therefore, even if the comparative example has a long pipe length or a large horsepower that requires a large amount of refrigerant, the refrigeration cycle device 1 of the first embodiment can use a flammable refrigerant.

Embodiment 2.
FIG. 9 is a circuit diagram showing a refrigeration cycle device 1A according to the second embodiment. As shown in FIG. 9, the second embodiment differs from the first embodiment in that the refrigeration cycle device 1A includes a sub-receiver 16. In Embodiment 2, the same parts as Embodiment 1 are given the same reference numerals and explanations are omitted, and differences from Embodiment 1 will be mainly explained.

The sub-receiver 16 is a container that stores refrigerant. The sub-receiver 16 is provided in a portion of the heat source side piping 21 closer to the connection piping 23 than the condenser 12, and constitutes a refrigerant circuit. The capacity of the sub-receiver 16 is smaller than the capacity of the receiver 41. Further, the total capacity of sub-receiver 16 and receiver 41 is approximately equal to the capacity of the receiver of the comparative example described in the first embodiment.

Similarly to the first embodiment, in the refrigeration cycle device 1A of the second embodiment, a receiver 41 that stores refrigerant is provided in the first bypass pipe 31. Therefore, the amount of refrigerant that stays in the receiver 41 during normal operation is smaller than the amount of refrigerant that stays in the receiver 41 when the receiver 41 is provided in series in the refrigerant circuit. Therefore, in the refrigeration cycle device 1A having the receiver 41, the amount of refrigerant sealed can be reduced.

Furthermore, it is generally assumed that the refrigerant density changes depending on the operating state of the refrigeration cycle device, and a large amount of refrigerant will remain in the condenser 12. In this case, the high pressure in the condenser increases and the performance of the condenser deteriorates. Such high pressure cuts are particularly likely to occur when the capacity of the condenser is small. A typical example of a condenser with a small capacity is a PFC heat exchanger (parallel flow condenser). If the performance of the condenser deteriorates significantly, an abnormal stop will occur. In the second embodiment, a sub-receiver 16 is added to the refrigerant circuit. As a result, while reducing the amount of refrigerant sealed in the refrigeration cycle device 1A, even when the distribution of the amount of refrigerant in the refrigerant circuit changes, the refrigerant remains in the condenser 12 in a liquid state for a long period of time. It is possible to prevent crowding.

Embodiment 3.
FIG. 10 is a circuit diagram showing a refrigeration cycle device 1B according to the third embodiment. As shown in FIG. 10, the third embodiment differs from the first embodiment in that the refrigeration cycle device 1B includes a third bypass pipe 33 and a fifth solenoid valve 55. In Embodiment 3, the same parts as Embodiment 1 are given the same reference numerals, explanations are omitted, and differences from Embodiment 1 will be mainly explained.

The third bypass pipe 33 connects the receiver 41 and the downstream side of the portion of the heat source side pipe 21 to which one end of the first bypass pipe 31 connects. In other words, the third bypass pipe 33 connects the receiver 41 and a part of the refrigerant pipe between the part of the refrigerant pipe to which one end of the first bypass pipe 31 connects and the first electromagnetic valve 51 . The distal end of the third bypass piping 33 is provided at a lower position than the other end of the first bypass piping 31, that is, the position of the distal end of the first bypass piping 31 in the receiver. Further, the tip of the third bypass piping 33 is provided at a lower position than the tip of the second bypass piping 32 in the receiver. The fifth solenoid valve 55 is provided in the third bypass piping 33. The fifth electromagnetic valve 55 has a function of switching between an open state that allows the refrigerant flowing through the third bypass pipe 33 to pass, and a closed state that blocks the refrigerant that flows through the third bypass pipe 33.

The refrigeration cycle device 1B has a first temperature sensor 61 and a pressure sensor 62. The first temperature sensor 61 and the pressure sensor 62 are both provided between the accumulator 15 and the compressor 11 in the heat source side piping 21. The first temperature sensor 61 measures the temperature of the refrigerant flowing through the heat source side piping 21 . The pressure sensor 62 measures the pressure of the refrigerant flowing through the heat source side piping 21 . The first temperature sensor 61 and the pressure sensor 62 transmit measurement results to the control device 90.

FIG. 11 is a diagram for explaining the control content of the control device 90 according to the third embodiment. As shown in FIG. 11, the control device 90 performs liquid back prevention operation in addition to normal operation and pump-down operation. In normal operation, the first solenoid valve 51, the third solenoid valve 53, and the fourth solenoid valve 54 are maintained in the open state, the second solenoid valve 52 and the fifth solenoid valve 55 are maintained in the closed state, and the compressor 11 is driven. In the pump down operation, the second solenoid valve 52 and the fourth solenoid valve 54 are maintained in the open state, the first solenoid valve 51, the third solenoid valve 53, and the fifth solenoid valve 55 are maintained in the closed state, and the compressor is 11 is driven. Further, when the operation of the refrigeration cycle device 1B is stopped, the control device 90 maintains the second solenoid valve 52 in an open state, and maintains the first solenoid valve 51, the third solenoid valve 53, the fourth solenoid valve 54, and the fifth solenoid valve. Valve 55 is maintained in a closed state, and driving of compressor 11 is stopped.

The liquid back prevention operation is performed immediately after the end of the pump-down operation or during normal operation, and is an operating method to prevent the compressor 11 from sucking liquid refrigerant, so-called liquid back. The liquid back prevention operation is executed when liquid back prevention start conditions are met. The liquid back prevention start condition is determined immediately after the end of the pump-down operation, that is, immediately after the pump-down end condition is satisfied, and at predetermined intervals during normal operation. The liquid back prevention starting condition is that the superheat value of the refrigerant estimated by the control device 90 based on the measurement results of the first temperature sensor 61 and the pressure sensor 62 is equal to or less than a predetermined threshold value. Further, the liquid back prevention operation ends when the liquid back prevention termination condition is satisfied. The liquid back prevention termination condition is, for example, that a predetermined period of time has elapsed since the start of the liquid back prevention operation. The predetermined time is, for example, 5 minutes. When the liquid back prevention operation ends, normal operation starts. In the liquid back prevention operation, the first solenoid valve 51, the third solenoid valve 53, the fourth solenoid valve 54, and the fifth solenoid valve 55 are maintained in the open state, the second solenoid valve 52 is maintained in the closed state, The compressor 11 is driven.

In the liquid back prevention operation, the liquid refrigerant stored in the receiver 41 passes through the fifth solenoid valve 55 and flows into the heat source side piping 21. This prevents the liquid refrigerant stored in the receiver 41 from flowing into the compressor 11 through the third electromagnetic valve 53 during the normal operation after the liquid back prevention operation ends.

The operation of the control device 90 will be explained using a flowchart. FIG. 12 is a flowchart showing the operation of the control device 90 according to the third embodiment. As described above, the liquid back prevention start condition is determined immediately after the end of the pump-down operation, that is, immediately after the pump-down end condition is satisfied, and at predetermined intervals during normal operation. Here, the description will focus on the liquid back prevention operation immediately after the end of the pump down operation and during normal operation. First, the control device 90 determines whether or not liquid back prevention start conditions are satisfied immediately after the end of the pump-down operation and during normal operation (step S11). In the determination immediately after the end of the pump-down operation, if the liquid back prevention start condition is not satisfied (step S11: NO), the control device 90 starts normal operation (step S14). Further, in the determination during normal operation, if the liquid back prevention start condition is not satisfied (step S11: NO), the control device 90 continues normal operation (step S14). When the liquid back prevention start condition is satisfied (step S11: YES), the control device 90 ends the pump down operation or normal operation and starts the liquid back prevention operation (step S12). Here, the first solenoid valve 51, the third solenoid valve 53, the fourth solenoid valve 54, and the fifth solenoid valve 55 are maintained in the open state, the second solenoid valve 52 is maintained in the closed state, and the compressor 11 drive.

Then, the control device 90 determines whether the liquid back prevention termination condition is satisfied during the liquid back prevention operation (step S13). If the liquid back prevention termination condition is not satisfied (step S13: NO), the process of step S13 is periodically repeated until the liquid back prevention termination condition is satisfied. If the liquid back prevention termination condition is satisfied (step S13: YES), the control device 90 ends the liquid back prevention operation and starts normal operation (step S14). Here, the first solenoid valve 51, the third solenoid valve 53, and the fourth solenoid valve 54 are maintained in the open state, the second solenoid valve 52 and the fifth solenoid valve 55 are maintained in the closed state, and the compressor 11 drive.

Similar to the first embodiment, in the refrigeration cycle device 1B of the third embodiment, a receiver 41 that stores refrigerant is provided in the first bypass pipe 31. Therefore, the amount of refrigerant that stays in the receiver 41 during normal operation is smaller than the amount of refrigerant that stays in the receiver 41 when the receiver 41 is provided in series in the refrigerant circuit. Therefore, in the refrigeration cycle device 1B having the receiver 41, the amount of refrigerant sealed can be reduced.

Furthermore, in the refrigeration cycle device 1B of the third embodiment, liquid back prevention operation is performed. Therefore, it is possible to suppress liquid backflow in which liquid refrigerant flows into the compressor 11 before the pump-down operation ends and normal operation resumes.

Embodiment 4.
FIG. 13 is a circuit diagram showing a refrigeration cycle device 1C according to the fourth embodiment. As shown in FIG. 13, the fourth embodiment differs from the first embodiment in that the refrigeration cycle device 1C includes a heater 43. In Embodiment 4, the same parts as in Embodiment 1 are given the same reference numerals and explanations are omitted, and differences from Embodiment 1 will be mainly explained.

The heater 43 is provided, for example, inside the receiver 41 or at a position in contact with the outer shell of the receiver 41. The heater 43 heats and evaporates the liquid refrigerant stored in the receiver 41. Furthermore, the refrigeration cycle device 1C includes a first temperature sensor 61 and a pressure sensor 62 similar to those in the third embodiment.

The heater 43 is activated when heater activation start conditions are met. The heater activation start condition is determined immediately after the end of the pump-down operation, that is, immediately after the pump-down end condition is satisfied, and at predetermined intervals during normal operation. Similar to the pump-down start condition described in the third embodiment, the heater activation start condition is a predetermined superheat value estimated by the control device 90 based on the measurement results of the first temperature sensor 61 and the pressure sensor 62. be below the specified threshold. Further, the heater 43 stops when the heater termination condition is satisfied. The heater termination condition is, for example, that a predetermined time has elapsed since the heater 43 was activated. The heater 43 does not operate during pump-down operation.

Similarly to the first embodiment, in the refrigeration cycle device 1C of the fourth embodiment, a receiver 41 that stores refrigerant is provided in the first bypass pipe 31. Therefore, the amount of refrigerant that stays in the receiver 41 during normal operation is smaller than the amount of refrigerant that stays in the receiver 41 when the receiver 41 is provided in series in the refrigerant circuit. Therefore, in the refrigeration cycle device 1C having the receiver 41, the amount of refrigerant sealed can be reduced.

Furthermore, the refrigeration cycle device 1C of the fourth embodiment includes a heater 43. Therefore, the refrigerant stored in the receiver 41 evaporates, and liquid refrigerant can be prevented from flowing into the compressor 11 during normal operation.

Embodiment 5.
FIG. 14 is a circuit diagram showing a refrigeration cycle device 1D according to the fifth embodiment. As shown in FIG. 14, the fifth embodiment differs from the first embodiment in that the refrigeration cycle device 1D includes a bypass expansion valve 44. In Embodiment 5, the same parts as in Embodiment 1 are given the same reference numerals and explanations are omitted, and differences from Embodiment 1 will be mainly explained.

The bypass expansion valve 44 is provided in the first bypass pipe 31 between the third electromagnetic valve 53 and the other end of the first bypass pipe 31, and expands the refrigerant flowing out from the receiver 41. The opening degree of the bypass expansion valve 44 is controlled by the control device 90. The control device 90 increases the opening degree of the bypass expansion valve 44 when the discharge temperature of the refrigerant detected by the second temperature sensor 71 provided on the discharge side of the compressor 11 becomes high. Further, the control device 90 reduces the opening degree of the bypass expansion valve 44 when the discharge temperature of the refrigerant detected by the second temperature sensor 71 becomes low.

Similar to the first embodiment, in the refrigeration cycle device 1D of the fifth embodiment, a receiver 41 that stores refrigerant is provided in the first bypass pipe 31. Therefore, the amount of refrigerant that stays in the receiver 41 during normal operation is smaller than the amount of refrigerant that stays in the receiver 41 when the receiver 41 is provided in series in the refrigerant circuit. Therefore, in the refrigeration cycle device 1D having the receiver 41, the amount of refrigerant sealed can be reduced.

Furthermore, it is generally known that when the compressor 11 sucks in wet steam, the discharge temperature decreases. According to the fifth embodiment, the refrigeration cycle device 1D includes a bypass expansion valve 44, and adjusts the opening degree of the bypass expansion valve 44 according to the discharge temperature. In particular, in the refrigeration cycle device 1D of the fifth embodiment, when the discharge temperature becomes low, the opening degree of the bypass expansion valve 44 is reduced. Therefore, the amount of liquid refrigerant flowing into the compressor 11 can be reduced.

The above is a description of the embodiment of the present disclosure, but the present disclosure is not limited to the configuration of the embodiment described above, and various modifications or combinations are possible within the scope of the technical idea. . For example, in the refrigeration cycle device 1 having the sub-receiver 16 described in the second embodiment, the third bypass piping 33 and the fifth solenoid valve 55 described in the third embodiment, the heater 43 described in the fourth embodiment, or One or more of the bypass expansion valves 44 described in the fifth embodiment may be provided. The same applies to combinations other than the second embodiment and the third to fifth embodiments.

The second bypass piping 32, capillary tube 42, and fourth electromagnetic valve 54 described in Embodiments 1 to 5 may be omitted. In this case as well, the refrigerant can be stored in the receiver 41, although the required time is longer than in the first to fifth embodiments. Furthermore, the accumulator 15 described in the first to fifth embodiments may be omitted.

Furthermore, the capillary tube 42 described in Embodiments 1 to 5 may be replaced with an expansion valve. The expansion valve is provided in the second bypass pipe 32 and expands the refrigerant flowing through the second bypass pipe 32 by reducing the pressure thereof, and is, for example, an electronic expansion valve. Both the capillary tube 42 and the expansion valve correspond to the "throttling device" in the present disclosure.

Furthermore, in the first to fifth embodiments, the control device 90 was described as maintaining the first electromagnetic valve 51 in the open state during normal operation. However, the first solenoid valve 51 may be in a closed state during normal operation unless the first bypass piping 31 is in a liquid-sealed state. Note that the liquid-sealed state means a state in which the piping is filled with liquid refrigerant and when the liquid refrigerant expands, the piping may be damaged.

Furthermore, in the first to fifth embodiments, the case where the expansion valve 13 is provided as a component of the refrigerant circuit has been described. However, the expansion valve 13 may be omitted from the refrigeration cycle device 1. FIG. 15 is a circuit diagram showing a refrigeration cycle device 1E according to a modification of the first embodiment. As shown in FIG. 15, in the refrigerant piping, only the first electromagnetic valve 51 is provided between the condenser 12 and the evaporator 14, and the expansion valve 13 of the first embodiment is not provided. In this case, the first electromagnetic valve 51 has the function of the expansion valve 13. Specifically, the first electromagnetic valve 51 controls the expansion of the refrigerant by controlling the length of time between the open state and the closed state by the control device 90, in the same way as when adjusting the opening degree in the expansion valve 13. The degree of this can be adjusted. However, the first solenoid valve 51 can be kept open and fully opened to allow all the refrigerant passing through the load-side piping 22 to flow, or it can be kept in the closed state and shut off all the refrigerant passing through the load-side piping 22. It can also be fully closed. Note that in the second to fifth embodiments as well, the expansion valve 13 may be omitted.

Furthermore, in the third embodiment, the liquid back prevention start condition was described as being determined immediately after the end of the pump-down operation and at predetermined intervals during normal operation. However, the determination of the liquid back prevention start condition may be made either immediately after the end of the pump down operation or during normal operation. Further, for example, if the accumulator 15 is not provided, the liquid back prevention start condition may be omitted so that the liquid back prevention operation is always executed when the pump down end condition is satisfied. . Regarding the omission of the heater start-up start condition in Embodiment 4 and the change in the timing at which the heater start-up start condition is determined, the omission of the liquid back prevention start condition and the determination of the liquid back prevention start condition in Embodiment 3 also apply. This is similar to changing the timing.

1, 1A, 1B, 1C, 1D, 1E Refrigeration cycle device, 2 Heat source equipment, 3 Load equipment, 11 Compressor, 12 Condenser, 13 Expansion valve, 14 Evaporator, 15 Accumulator, 16 Sub-receiver, 21 Heat source side piping , 22 Load side piping, 23 Connection piping, 24 Connection piping, 31 First bypass piping, 32 Second bypass piping, 33 Third bypass piping, 41 Receiver, 42 Capillary tube, 43 Heater, 44 Bypass expansion valve, 51 First Solenoid valve, 52 second solenoid valve, 53 third solenoid valve, 54 fourth solenoid valve, 55 fifth solenoid valve, 61 first temperature sensor, 62 pressure sensor, 71 second temperature sensor, 90 control device, 91 processing circuit , 92 processor, 93 memory, 94 bus.

Claims

a refrigerant circuit in which a compressor, a condenser, and an evaporator are connected by refrigerant piping, and a refrigerant flows;
a first electromagnetic device that is provided between the condenser and the evaporator in the refrigerant piping and has a function of switching between an open state that allows refrigerant flowing through the refrigerant circuit to pass through and a closed state that blocks refrigerant that flows through the refrigerant circuit; valve and
A first bypass pipe, one end of which connects to a portion of the refrigerant piping between the condenser and the first solenoid valve, and the other end of which connects to a portion of the refrigerant piping between the evaporator and the compressor. and,
a receiver provided in the first bypass pipe and storing refrigerant;
The first bypass piping is provided between the one end of the first bypass piping and the receiver, and switches between an open state that allows refrigerant flowing to the receiver to pass through and a closed state that blocks refrigerant that flows to the receiver. a second solenoid valve having a function;
The first bypass piping is provided between the receiver and the other end of the first bypass piping, and has an open state that allows the refrigerant flowing from the receiver to pass through, and a closed state that blocks the refrigerant that flows from the receiver. a third solenoid valve having a switching function;
a control device that controls the compressor, the first solenoid valve, the second solenoid valve, and the third solenoid valve,
The control device includes:
a normal operation in which the compressor is driven by maintaining the first solenoid valve in the open state and maintaining the second solenoid valve in the closed state;
A pump-down operation is performed in which the second solenoid valve is maintained in the open state, the first solenoid valve and the third solenoid valve are maintained in the closed state, and the compressor is driven. .
The control device includes:
The refrigeration cycle device according to claim 1, wherein the third solenoid valve is maintained in the open state during the normal operation.
a second bypass piping that connects the receiver and a portion of the first bypass piping between the second solenoid valve and the other end of the first bypass piping;
Further, a fourth electromagnetic valve is provided in the second bypass pipe and has a function of switching between an open state that allows refrigerant flowing through the second bypass pipe to pass and a closed state that blocks refrigerant flowing through the second bypass pipe. Prepare,
The control device includes:
The refrigeration cycle device according to claim 1 or 2, wherein the fourth solenoid valve is maintained in the open state during the normal operation and the pump-down operation.
The refrigeration cycle device according to claim 3, further comprising a throttle device that is provided in the second bypass pipe and expands the refrigerant flowing through the second bypass pipe.
The refrigeration cycle device according to any one of claims 1 to 4, further comprising a sub-receiver that is provided in the refrigerant pipe and stores refrigerant.
The refrigeration cycle device according to claim 5, wherein the capacity of the sub-receiver is smaller than the capacity of the receiver.
a third bypass piping that connects the receiver and a portion of the refrigerant piping between a portion of the refrigerant piping that is connected to the one end of the first bypass piping and the first electromagnetic valve;
Further, a fifth solenoid valve is provided in the third bypass pipe and has a function of switching between an open state that allows refrigerant flowing through the third bypass pipe to pass and a closed state that blocks refrigerant flowing through the third bypass pipe. Prepare,
The control device includes:
liquid back prevention operation in which the compressor is driven by maintaining the second solenoid valve in the open state and maintaining the first solenoid valve, the third solenoid valve, and the fifth solenoid valve in the closed state; The refrigeration cycle device according to any one of claims 1 to 6, wherein the refrigeration cycle device performs the following.
The refrigeration cycle device according to any one of claims 1 to 7, further comprising a heater provided in the receiver and heating the refrigerant stored in the receiver.
The first bypass pipe further includes a bypass expansion valve that is provided between the third electromagnetic valve and the other end of the first bypass pipe and expands the refrigerant flowing out from the receiver. The refrigeration cycle device according to any one of the above.
The refrigeration cycle device according to claim 1, wherein the refrigerant is a flammable refrigerant.