WO2023281653A1

WO2023281653A1 - Accumulator and refrigeration cycle device

Info

Publication number: WO2023281653A1
Application number: PCT/JP2021/025601
Authority: WO
Inventors: 宗希石山
Original assignee: 三菱電機株式会社
Priority date: 2021-07-07
Filing date: 2021-07-07
Publication date: 2023-01-12
Also published as: CN117581070A; JPWO2023281653A1; EP4368920A1

Abstract

An accumulator (5) comprises: a container (51) that stores refrigerant; an inlet pipe (52) for allowing the refrigerant to flow into the container (51); an outlet pipe (53) for allowing the refrigerant to flow outside the container (51); an oil return unit (54) in which an opening for sucking oil is provided; and a decompression pipe (56) that decompresses the refrigerant. The accumulator (5) is configured by the decompression pipe (56) and oil return unit (54) being arranged on the outlet pipe (53).

Description

Accumulator and refrigeration cycle equipment

The present disclosure relates to accumulators and refrigeration cycle devices.

A refrigeration cycle device equipped with an accumulator is conventionally known. The accumulator is installed between the evaporator and the compressor. Refrigerant that has flowed out of the evaporator flows into the accumulator. The refrigerant flowing into the accumulator is composed of a gaseous refrigerant and a liquid mixture. The liquid mixture contains liquid refrigerant and oil for lubricating the compressor. The accumulator prevents liquid backflow, in which the liquid refrigerant flows into the compressor, by storing excess liquid refrigerant. The accumulator prevents oil depletion caused by an increase in the amount of oil discharged from the compressor by returning oil from the oil return portion.

If the diameter of the hole in the oil return part is too large, the inflow flow rate increases and liquid back may occur. If the diameter of the hole is simply reduced, there is a possibility that the inflow flow rate will be too small, resulting in insufficient oil return. In order to increase the amount of returned oil, it is conceivable to lengthen the outflow pipe or provide a separate straw pipe for returning oil, but this would result in an increase in the size of the device.

Japanese Patent Application Laid-Open No. 2014-203736 (Patent Document 1) discloses a gas-liquid separation device as an accumulator, by adjusting the opening of a liquid return hole as an oil return section, thereby adjusting the inflow ratio of the mixed liquid. A rate adjuster is provided.

JP 2014-203736 A

In the refrigeration cycle device of Patent Document 1, the hole opening degree adjustment valve provided in the mixture ratio adjustment device is operated by driving the electric motor in order to suppress the overheating state of the refrigerant. Although the refrigeration cycle device of Patent Document 1 can adjust the flow rate of the mixed liquid flowing into the compressor from the accumulator, it cannot return an appropriate amount of oil because it does not consider the amount of oil in the mixed liquid, and the mixing ratio can be adjusted. The device was a large one with an electric motor.

An object of the present disclosure is to provide a compact accumulator and refrigeration cycle device that can flow an appropriate amount of oil into the compressor.

The present disclosure relates to an accumulator installed between an evaporator of a refrigeration cycle device and a refrigerant suction side of a compressor. The accumulator includes a container for storing the refrigerant, an inflow pipe for inflowing the refrigerant into the container, an outflow pipe for flowing the refrigerant out of the container, and an oil return portion provided with an opening for sucking the oil. and a decompression device that decompresses the refrigerant. The accumulator has a pressure reducing device and an oil return on the outflow line.

According to the present disclosure, a small accumulator allows an appropriate amount of oil to flow into the compressor.

1 is a diagram showing a circuit configuration of a refrigeration cycle device according to Embodiment 1; FIG. FIG. 2 is a diagram for explaining an accumulator according to Embodiment 1; FIG. FIG. 3 is a view showing the III-III cross section of FIG. 2; FIG. 11 is a diagram for explaining an accumulator according to Embodiment 2; FIG. FIG. 5 is a view showing a VV cross section of FIG. 4; FIG. 10 is a diagram showing a circuit configuration of a refrigeration cycle apparatus according to Embodiment 3; FIG. 11 is a diagram for explaining an accumulator according to Embodiment 3; FIG. 10 is a flow chart showing control of a second expansion valve in Embodiment 3. FIG. FIG. 10 is a diagram showing a circuit configuration of a refrigeration cycle apparatus according to Embodiment 4; 14 is a flow chart showing control of a second expansion valve in Embodiment 4. FIG. FIG. 10 is a diagram showing a circuit configuration of a refrigeration cycle apparatus according to Embodiment 5; 14 is a flow chart showing control of a first expansion valve and a second expansion valve in Embodiment 5. FIG. FIG. 11 is a diagram showing a circuit configuration of a refrigeration cycle apparatus according to Embodiment 6;

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments described below, when referring to the number, amount, etc., the scope of the present disclosure is not necessarily limited to the number, amount, etc., unless otherwise specified. The same reference numbers are given to the same parts and equivalent parts, and redundant description may not be repeated. It is planned from the beginning to use the configurations in the embodiments in combination as appropriate.

Embodiment 1.
<Circuit Configuration of Refrigeration Cycle Device 100>
FIG. 1 is a diagram showing a circuit configuration of a refrigeration cycle apparatus 100 according to Embodiment 1. FIG. A refrigeration cycle device 100 includes a compressor 1 , a first heat exchanger 2 , a second heat exchanger 4 , a first expansion valve 3 , an accumulator 5 , and a control device 10 .

The refrigeration cycle device 100 circulates the refrigerant in the order of the compressor 1, the first heat exchanger 2, the first expansion valve 3, the second heat exchanger 4, and the accumulator 5 during the heating operation.

The compressor 1 sucks, compresses, and discharges the refrigerant. The first heat exchanger 2 functions as a condenser. The first heat exchanger 2 uses a fan (not shown) to exchange heat between the air and the refrigerant to condense the refrigerant. The first expansion valve 3 is arranged between the first heat exchanger 2 and the second heat exchanger 4 and expands or decompresses the refrigerant. The first expansion valve 3 is a device capable of arbitrarily controlling the degree of opening, such as an electronic expansion valve. The degree of opening of the first expansion valve 3 is controlled by the controller 10 .

The second heat exchanger 4 functions as an evaporator. The second heat exchanger 4 evaporates the low-pressure liquid refrigerant decompressed by the first expansion valve 3 . The gas-liquid two-phase refrigerant evaporated in the second heat exchanger 4 flows into the accumulator 5 . A refrigerant circuit of the refrigerating cycle device 100 is filled with refrigerating machine oil (hereinafter also simply referred to as oil). An accumulator 5 installed between the compressor 1 and the second heat exchanger 4 separates a gas-liquid two-phase refrigerant composed of a gas refrigerant and a mixture of oil and liquid refrigerant. After passing through the accumulator 5 , the gas refrigerant and the mixed liquid whose oil amount has been adjusted return to the compressor 1 .

The control device 10 includes a CPU (Central Processing Unit) 11, a memory 12 (ROM (Read Only Memory) and RAM (Random Access Memory)), and an input/output device (not shown) for inputting various signals. be done. The CPU 11 expands a program stored in the ROM into the RAM or the like and executes it. The program stored in the ROM is a program in which processing procedures of the control device 10 are described. The control device 10 controls each device in the refrigeration cycle device 100 according to these programs. This control is not limited to processing by software, and processing by dedicated hardware (electronic circuit) is also possible.

<Configuration of accumulator 5>
FIG. 2 is a diagram for explaining the accumulator 5 according to the first embodiment. The accumulator 5 includes a container 51, an inflow pipe 52, an outflow pipe 53, an oil return portion 54, and a pressure reducing pipe 56 as a pressure reducing device.

The container 51 stores a mixed liquid of liquid refrigerant and oil. The inflow pipe 52 is used to flow the gas refrigerant and the liquid mixture into the container 51 . The inflow pipe 52 has a shape in which the tip is bent toward the wall surface inside the container 51 . The outflow pipe 53 is bent in a U shape, and the gas refrigerant flows in from the inlet of the outflow pipe 53, out of the gas refrigerant and the liquid mixture. From the outlet of the outflow pipe 53, the gas refrigerant and the mixed liquid in which the amount of oil is adjusted flow out. The outflow pipe 53 has a shape in which the inflow end of the gas refrigerant is positioned higher than the oil return portion 54 and the decompression pipe 56 in the container 51 , and the outflow end of the gas refrigerant protrudes outside the container 51 . be.

The oil return portion 54 is an opening for sucking oil formed in the arc portion of the outflow pipe 53 . The accumulator 5 returns the oil (refrigerating machine oil) to the compressor 1 as a mixed liquid together with a small amount of liquid refrigerant by returning the oil from the oil return portion 54, thereby preventing the liquid backflow that lowers the performance and reliability of the compressor 1. . The gas refrigerant and oil flow out from the outlet of the outflow pipe 53 . The opening of the oil return portion 54 is provided with a mesh-like cover for removing dust, but the illustration is omitted for the sake of explanation.

The decompression pipe 56 is provided between the inlet of the outflow pipe 53 and the oil return portion 54 and has a diameter smaller than that of the outflow pipe 53 . The decompression pipe 56 decompresses the gas refrigerant. If the decompression pipe 56 is provided at the tip of the outflow pipe 53, the flow velocity at the tip increases and the efficiency of gas-liquid separation deteriorates. can be done.

FIG. 3 is a diagram showing the III-III cross section of FIG. As shown in FIG. 3 , the outflow pipe 53 is provided with an oil return portion 54 formed with a hole having a smaller diameter than the diameter of the outflow pipe 53 . Assuming that the pressure inside the outflow pipe 53 is P1, the pressure outside the outflow pipe 53 is P2, and the pressure in the oil return portion 54 is ΔP, there is a relationship of P2>P1. The flow rate flowing through the oil return portion 54 is determined by the relationship of P2-P1=ΔP.

<Refrigerant flow>
The flow of refrigerant in Embodiment 1 will be described. The mixture of gas refrigerant and liquid refrigerant and oil that has flowed out of the second heat exchanger 4 flows into the accumulator 5 . The gas refrigerant and mixed liquid pass through the inflow pipe 52 of the accumulator 5 and flow into the container 51 . The gas refrigerant and the mixed liquid are gas-liquid separated, the gas refrigerant flows into the outflow pipe 53 , and the mixed liquid accumulates in the container 51 . The gas refrigerant that has flowed into the outflow pipe 53 flows while the pressure decreases when passing through the decompression pipe 56 . A pressure drop can also be rephrased as a pressure loss.

The mixed liquid accumulated in the container 51 flows into the outflow pipe 53 from the oil return portion 54 . In the accumulator 5, according to the pressure difference ΔP between the inlet pressure P2 of the oil return portion 54 in the container 51 and the pressure P1 inside the outflow pipe 53, the oil in the lower part of the mixture flows from the oil return portion 54, Merges with gas refrigerant. The combined gas refrigerant and oil flow out of the accumulator 5 through the outflow pipe 53 and into the compressor 1 .

If the diameter of the hole of the oil return portion 54 is made too large, the inflow flow rate increases and liquid back may occur. If the diameter of the hole is simply reduced, there is a possibility that the inflow flow rate will be too small, resulting in insufficient oil return. In order to increase the amount of returned oil, it is possible to lengthen the distance from the end of the outflow pipe 53 to the hole, or to separately provide a straw pipe for returning oil, but this would increase the size of the device.

The accumulator 5 of the present embodiment is arranged in the middle of the outflow pipe 53 in the order of the decompression pipe 56 and the oil return portion 54 with respect to the flow direction of the refrigerant. Therefore, the differential pressure can be increased without increasing the size of the accumulator 5 , and an appropriate amount of oil can flow into the compressor 1 .

Embodiment 2.
<Configuration of accumulator 5A>
FIG. 4 is a diagram for explaining the accumulator 5A of the second embodiment. Compared with the accumulator 5 of Embodiment 1, the accumulator 5A of Embodiment 2 has two oil return portions, namely, a first oil return portion 54A and a second oil return portion 54B. It is different in that it is arranged between the oil return parts. Other configurations are the same as those of the accumulator 5 of the first embodiment. In the following description, points different from the first embodiment are mainly described.

The first oil return portion 54A and the second oil return portion 54B are openings formed in the arc portion of the outflow pipe 53 for sucking oil. The accumulator 5A returns oil to the compressor 1 by returning oil from the first oil return portion 54A and the second oil return portion 54B, and prevents liquid backflow that causes deterioration in performance and reliability of the compressor 1. The gas refrigerant and oil flow out from the outlet of the outflow pipe 53 .

The decompression pipe 56 is provided between the first oil return portion 54A and the second oil return portion 54B, and has a smaller diameter than the outflow pipe 53. The decompression pipe 56 decompresses the gas refrigerant and the liquid mixture.

FIG. 5 is a diagram showing a VV cross section in FIG. As shown in FIG. 5, the outflow pipe 53 is formed with a second oil return portion 54B having a diameter smaller than that of the outflow pipe 53 . Assuming that the pressure inside the outflow pipe 53 is P1', the pressure outside the outflow pipe 53 is P2', and the pressure in the second oil return portion 54B is ΔP', there is a relationship of P2'>P1'. The flow rate flowing through the second oil return portion 54B is determined by the relationship of P2'-P1'=.DELTA.P'.

The first oil return portion 54A in the III-III cross section of FIG. 4 is the same as the oil return portion 54 of FIG. Assuming that the pressure inside the outflow pipe 53 is P1, the pressure outside the outflow pipe is P2, and the pressure in the first oil return portion 54A is ΔP, there is a relationship of P2>P1. The flow rate flowing through the first oil return portion 54A is determined by the relationship of P2-P1=ΔP.

In the accumulator 5A, there is a relationship of P2≈P2' and a relationship of P1>P1' due to the decompression pipe 56. Therefore, the flow rate through the second oil return portion 54B is greater than the flow rate through the first oil return portion 54A.

<Refrigerant flow>
The flow of refrigerant in Embodiment 2 will be described. The mixture of the gas refrigerant and the liquid refrigerant and the oil that has flowed out of the second heat exchanger 4 flows into the accumulator 5A. The gas refrigerant and mixed liquid flow into the container 51 through the inflow pipe 52 of the accumulator 5A. The gas refrigerant and the mixed liquid are gas-liquid separated, the gas refrigerant flows into the outflow pipe 53 , and the mixed liquid accumulates in the container 51 . The gas refrigerant that has flowed into the outflow pipe 53 flows while the pressure decreases when passing through the decompression pipe 56 .

The liquid mixture accumulated in the container 51 flows into the outflow pipe 53 from the first oil return portion 54A. In the accumulator 5A, according to the pressure difference ΔP between the pressure P2, which is the inlet pressure of the first oil return portion 54A in the container 51, and the pressure P1 inside the outflow pipe 53, the oil in the lower part of the mixture is discharged from the first oil return portion 54A. flows in and joins the gas refrigerant. The merged gas refrigerant and oil flow while the pressure decreases when passing through the decompression pipe 56 .

After that, the mixed liquid accumulated in the container 51 flows into the outflow pipe 53 from the second oil return portion 54B. The liquid mixture flows from the second oil return section 54B to the bottom of the liquid mixture according to the pressure difference ΔP' between the pressure P2' which is the inlet pressure of the second oil return section 54B in the container 51 and the pressure P1' inside the outflow pipe 53. Some oil will flow in. The combined gas refrigerant and oil flow out of the accumulator 5 through the outflow pipe 53 and into the compressor 1 .

The accumulator 5A is arranged in the middle of the outflow pipe 53 in the order of the first oil return portion 54A, the decompression pipe 56, and the second oil return portion 54B with respect to the flow direction of the refrigerant. Therefore, when the refrigerant flow rate in the refrigerant circuit is small, the inflow flow rate to the first oil return portion 54A is reduced, liquid backflow is suppressed, and performance can be improved. When the flow rate of refrigerant in the refrigerant circuit is large, oil can be returned by the first oil return portion 54A and the second oil return portion 54B, thereby improving reliability. Thus, an appropriate amount of oil can flow into the compressor 1 without enlarging the accumulator 5A.

Embodiment 3.
<Circuit Configuration of Refrigeration Cycle Device 100A>
FIG. 6 is a diagram showing a circuit configuration of a refrigeration cycle apparatus 100A according to Embodiment 3. As shown in FIG. Compared with the refrigerating cycle device 100 of the first embodiment, the refrigerating cycle device 100A of the third embodiment has an accumulator 5B instead of the accumulator 5, and a discharge superheat sensor 61 serving as a detection sensor performs first heat exchange with the compressor 1. The point provided between the vessel 2 is different. Other configurations are the same as those of the refrigeration cycle apparatus 100 of the first embodiment. In the following description, points different from the first embodiment are mainly described.

The discharge superheat sensor 61 is a sensor for detecting the degree of superheat of the refrigerant discharged from the compressor 1 . The discharge superheat is the temperature difference between the temperature of the refrigerant discharged by the compressor 1 (hereinafter also referred to as discharge temperature) and the saturated gas temperature corresponding to the pressure of the refrigerant discharged by the compressor (hereinafter also referred to as discharge pressure). is the degree of superheat of the refrigerant gas represented by A discharge superheat sensor 61 measures the discharge temperature and the discharge pressure. The measured signal is transmitted to the control device 10 . The controller 10 obtains the degree of discharge superheat as a detection value from the detected signal value. A differential pressure gauge may be used as the discharge superheat sensor 61 .

<Configuration of accumulator 5B>
FIG. 7 is a diagram for explaining the accumulator 5B of the third embodiment. The accumulator 5B of the third embodiment differs from the accumulator 5 of the first embodiment in that the position of the oil return portion 54 and that a second expansion valve 57 is arranged instead of the pressure reducing pipe 56 as a pressure reducing device. ing. Other configurations are the same as those of the accumulator 5 of the first embodiment. In the following description, points different from the first embodiment are mainly described.

The oil return portion 54 is an opening for sucking oil formed near the center of the arc portion of the outflow pipe 53 . The second expansion valve 57 is provided between the inlet of the outflow pipe 53 and the oil return portion 54 and reduces the pressure of the gas refrigerant flowing in from the outflow pipe 53 . The second expansion valve 57 can adjust the degree of opening in accordance with the flow rate flowing through the refrigerant circuit. As shown in FIG. 6, the control device 10 controls the degree of opening of the second expansion valve 57 based on the detected value of the degree of discharge superheat.

<Regarding control of the second expansion valve 57>
FIG. 8 is a flow chart showing control of the second expansion valve 57 in the third embodiment. As shown in FIG. 8, the control device 10 determines whether or not the compressor 1 is in operation in step S1. When the controller 10 determines that the compressor 1 is not in operation (NO in step S1), the process ends. When the controller 10 determines that the compressor 1 is in operation (YES in step S1), the process proceeds to step S2.

The controller 10 acquires the detected value of the discharge superheat from the value of the discharge superheat sensor 61 in step S2. Next, control device 10 compares a predetermined reference value with the detected value (step S3). When the control device 10 determines that the detected value is smaller than the reference value (YES in step S3), it reduces the degree of opening of the second expansion valve 57 from the current degree of opening (step S4), and proceeds to the process of step S1. do. When the control device 10 determines that the detected value is equal to or greater than the reference value (NO in step S3), it increases the degree of opening of the second expansion valve 57 from the current degree of opening (step S5), and performs the processing of step S1. Move to

The control device 10 may increase or decrease the degree of opening of the second expansion valve 57 in predetermined steps. The control device 10 may end the opening degree adjustment process when the opening degree of the second expansion valve 57 reaches a predetermined minimum opening degree or a predetermined maximum opening degree.

<Refrigerant flow>
The flow of refrigerant in Embodiment 3 will be described. The mixture of gas refrigerant and liquid refrigerant and oil that has flowed out of the second heat exchanger 4 flows into the accumulator 5B. The gas refrigerant and mixed liquid flow into the container 51 through the inflow pipe 52 of the accumulator 5B. The gas refrigerant and the mixed liquid are gas-liquid separated, the gas refrigerant flows into the outflow pipe 53 , and the mixed liquid accumulates in the container 51 . The gas refrigerant that has flowed into the outflow pipe 53 flows while the pressure decreases when passing through the second expansion valve 57 .

<About unstable operation such as startup>
In the refrigeration cycle apparatus 100A, the detected value becomes smaller than the reference value during unstable operation such as when the compressor 1 is started. In this case, as shown in step S4 in FIG. 8, the degree of opening of the second expansion valve 57 is decreased from the current degree of opening. In the accumulator 5B, as the degree of opening of the second expansion valve 57 decreases, the pressure drop at the second expansion valve 57 increases.

As a result, in the refrigeration cycle device 100A, the pressure difference between the inlet and outlet of the outflow pipe 53 can be increased without enlarging the accumulator 5B, and the flow rate of oil flowing into the oil return portion 54 is increased. The refrigeration cycle device 100A can suppress oil depletion by increasing the amount of oil returned to the compressor 1 and improve reliability when oil return is required during unstable operation such as startup. can.

<About stable operation>
In the refrigeration cycle apparatus 100A, the detected value is equal to or greater than the reference value when the compressor 1 is in stable operation. In this case, as shown in step S5 of FIG. 8, the degree of opening of the second expansion valve 57 increases from the current degree of opening. In the accumulator 5B, as the degree of opening of the second expansion valve 57 increases, the pressure drop at the second expansion valve 57 decreases.

As a result, in the refrigeration cycle device 100A, the pressure difference between the inlet and outlet of the outflow pipe 53 can be reduced without increasing the size of the accumulator 5B, and the flow rate of oil flowing into the oil return portion 54 is reduced. The refrigeration cycle device 100A can prevent liquid backflow by reducing the amount of oil returned to the compressor 1 when there is no need to return oil during stable operation, thereby improving reliability and performance. be able to. In the refrigeration cycle device 100A, the pressure loss in the outflow pipe 53 is small during stable operation, so the performance of the entire circuit device can be improved.

Embodiment 4.
<Circuit Configuration of Refrigeration Cycle Device 100B>
FIG. 9 is a diagram showing a circuit configuration of a refrigeration cycle device 100B according to Embodiment 4. As shown in FIG. A refrigerating cycle apparatus 100B of the fourth embodiment differs from the refrigerating cycle apparatus 100A of the third embodiment in that an oil concentration sensor 62 is provided in the compressor 1 instead of the discharge superheat sensor 61 as a detection sensor. is different. Other configurations are the same as those of the refrigeration cycle apparatus 100A of the third embodiment. In the following description, points different from the third embodiment are mainly described.

The oil concentration sensor 62 is a sensor for detecting the concentration of oil inside the compressor 1 . A signal regarding the oil concentration measured by the oil concentration sensor is transmitted to the control device 10 . The control device 10 obtains the oil concentration as a detected value from the detected signal value. The control device 10 controls the second expansion valve 57 based on the detected value of the oil concentration. The oil concentration sensor 62 may be a sensor for detecting the state of the liquid, such as a sensor that detects liquid concentration by electrostatic capacitance, a sensor that detects ultrasonic waves, a sensor that detects refractive index, or the like.

<Regarding control of the second expansion valve 57>
FIG. 10 is a flow chart showing control of the second expansion valve 57 in the fourth embodiment. As shown in FIG. 10, in step S11, the control device 10 determines whether or not the compressor 1 is in operation. When the controller 10 determines that the compressor 1 is not in operation (NO in step S11), the process ends. When the controller 10 determines that the compressor 1 is in operation (YES in step S11), the process proceeds to step S12.

The control device 10 acquires the detection value of the oil concentration sensor 62 in step S12. Next, the control device 10 compares a predetermined reference value and the detected value (step S13). When the control device 10 determines that the detected value is smaller than the reference value (YES in step S13), the opening degree of the second expansion valve 57 is decreased from the current opening degree (step S14), and the process proceeds to step S11. do. When the control device 10 determines that the detected value is equal to or greater than the reference value (NO in step S13), it increases the degree of opening of the second expansion valve 57 from the current degree of opening (step S15), and performs the processing of step S11. to

<About unstable operation such as startup>
In the refrigeration cycle apparatus 100B, the detected value becomes smaller than the reference value during unstable operation such as when the compressor 1 is started. In this case, as shown in step S14 of FIG. 10, the degree of opening of the second expansion valve 57 is reduced from the current degree of opening. In the accumulator 5B, as the degree of opening of the second expansion valve 57 decreases, the pressure drop at the second expansion valve 57 increases.

As a result, in the refrigeration cycle device 100B, the pressure difference between the inlet and the outlet of the outflow pipe 53 can be increased without increasing the size of the accumulator 5B, and the flow rate of oil flowing into the oil return portion 54 is increased. The refrigeration cycle device 100B increases the amount of oil returned to the compressor 1 when oil is required to be returned during unstable operation such as startup, thereby suppressing oil depletion and improving reliability. can.

<About stable operation>
In the refrigerating cycle device 100B, the detected value is equal to or greater than the reference value when the compressor 1 is in stable operation. In this case, as shown in step S15 of FIG. 10, the degree of opening of the second expansion valve 57 increases from the current degree of opening. In the accumulator 5B, as the degree of opening of the second expansion valve 57 increases, the pressure drop at the second expansion valve 57 decreases.

As a result, in the refrigeration cycle device 100B, the pressure difference between the inlet and the outlet of the outflow pipe 53 can be reduced without increasing the size of the accumulator 5B, and the flow rate of oil flowing into the oil return portion 54 is reduced. The refrigeration cycle device 100B can prevent liquid backflow by reducing the amount of oil returned to the compressor 1 when there is no need to return oil during stable operation, thereby improving reliability and performance. be able to. In the refrigeration cycle device 100B, the pressure loss in the outflow pipe 53 is small during stable operation, so the performance of the entire circuit device can be improved.

Embodiment 5.
<Circuit Configuration of Refrigeration Cycle Device 100B>
FIG. 11 is a diagram showing a circuit configuration of a refrigeration cycle apparatus 100C according to Embodiment 5. As shown in FIG. Compared with the refrigerating cycle apparatus 100A of the third embodiment, the refrigerating cycle apparatus 100B of the fifth embodiment has an intake superheat sensor 63 instead of the discharge superheat sensor 61 as a detection sensor in the second heat exchanger 4 and the accumulator 5B. The difference is that it is provided between Other configurations are the same as those of the refrigeration cycle apparatus 100A of the third embodiment. In the following description, points different from the third embodiment are mainly described.

The intake superheat sensor 63 is a sensor for detecting the degree of superheat of the refrigerant sucked into the compressor 1 . The suction superheat is the temperature difference between the temperature of the refrigerant sucked by the compressor 1 (hereinafter also referred to as suction temperature) and the saturated gas temperature corresponding to the pressure of the refrigerant sucked by the compressor (hereinafter also referred to as suction pressure). is the degree of superheat of the refrigerant gas represented by The intake superheat sensor 63 measures the intake temperature and the intake pressure. The measured signal is transmitted to the control device 10 . The controller 10 obtains the degree of suction superheat as a detection value from the detected signal value. The control device 10 controls the second expansion valve 57 based on the detected value of the degree of suction superheat. A differential pressure gauge may be used as the intake superheat sensor 63 .

<Regarding control of the second expansion valve 57>
FIG. 12 is a flow chart showing control of the first expansion valve 3 and the second expansion valve 57 in the fifth embodiment. As shown in FIG. 12, in step S21, the control device 10 determines whether or not a signal for stopping operation of the compressor 1 transmitted to the control device 10 by user's operation has been received. If the control device 10 determines that the operation stop signal for the compressor 1 has not been received (NO in step S21), the process ends. If the control device 10 determines that it has received the operation stop signal for the compressor 1 (YES in step S21), the process proceeds to step S22.

In step S22, the control device 10 determines whether or not the compressor 1 is in operation. When the controller 10 determines that the compressor 1 is not in operation (NO in step S22), the process ends. When the controller 10 determines that the compressor 1 is in operation (YES in step S22), the process proceeds to step S23.

In step S23, the control device 10 acquires the detected value of the degree of suction superheat from the value of the degree of suction superheat sensor 63. Next, in step S24, the controller increases the degree of opening of the second expansion valve 57 from the current degree of opening. Next, the control device 10 compares the predetermined reference value and the detected value (step S25). When the control device 10 determines that the detected value is smaller than the reference value (YES in step S25), the opening degree of the first expansion valve 3 is decreased from the current opening degree (step S26), and the process proceeds to step S21. do. If the control device 10 determines that the detected value is equal to or greater than the reference value (NO in step S25), it increases the degree of opening of the first expansion valve 3 from the current degree of opening (step S27), and performs the processing of step S21. Move to

In step S21, the control device 10 starts counting from the time when the operation stop signal of the compressor 1 is received, increases the count value when proceeding to step S26, and increases the count value when proceeding to step S27. Reset and set the stop flag. The control device 10 may determine that the operation of the compressor 1 has been stopped when the stop flag is set. In the processing of steps S21 and S22, the control device 10 controls the opening degrees of the first expansion valve 3 and the second expansion valve 57 in the processing from when the stop signal for the compressor 1 is received until the compressor 1 is completely stopped. to adjust. As a result, the degree of suction superheat can be sufficiently improved from when the stop signal for the compressor 1 is received to when the compressor 1 is completely stopped.

The control device 10 may increase or decrease the opening degrees of the first expansion valve 3 and the second expansion valve 57 in predetermined steps. When the opening degrees of the first expansion valve 3 and the second expansion valve 57 reach a predetermined minimum opening degree or a predetermined maximum opening degree, the control device 10 ends the opening adjustment process. Just do it.

<When receiving a stop signal>
In the refrigeration cycle device 100C, when the control device 10 receives a signal to stop the compressor 1, the dryness of the refrigerant at the inlet of the accumulator 5B may increase due to continued operation. In such a case, gas refrigerant and oil flow into the accumulator 5B. The gas refrigerant and oil flow into the container 51 through the inflow pipe 52 of the accumulator 5B. Gas refrigerant and oil are gas-liquid separated, the gas refrigerant flows into the outflow pipe 53 , and the oil accumulates in the container 51 .

In the refrigeration cycle apparatus 100C, the control device 10, as shown in steps S21 to S24, keeps the second expansion valve 57 open during the period from when the stop signal for the compressor 1 is received until the compressor 1 is completely stopped. Increase the opening from the current opening. In the accumulator 5B, as the degree of opening of the second expansion valve 57 increases, the pressure drop at the second expansion valve 57 decreases.

As a result, in the refrigeration cycle device 100C, the pressure difference between the inlet and the outlet of the outflow pipe 53 can be reduced without increasing the size of the accumulator 5B, and the flow rate of oil flowing into the oil return portion 54 is reduced. The refrigeration cycle device 100C can improve reliability by accumulating oil necessary for start-up in the container 51 of the accumulator 5B when operation is stopped.

In the refrigeration cycle apparatus 100C, when the detected value is smaller than the reference value, the control device 10 reduces the opening degree of the first expansion valve 3 from the current opening degree as shown in step S26. Increase the pressure drop across valve 3 . As a result, the degree of suction superheat increases by increasing the dryness of the refrigerant. By increasing the degree of suction superheat, the amount of oil flowing into the accumulator 5B can be increased.

In the refrigeration cycle apparatus 100C, when the detected value is equal to or greater than the reference value, the control device 10 increases the degree of opening of the first expansion valve 3 from the current degree of opening as shown in step S27. Reduce the pressure drop at 3. As a result, the dryness of the refrigerant decreases and the degree of suction superheat decreases. As the degree of suction superheat drops, the amount of oil flowing into the accumulator 5B can be reduced.

In this way, in the refrigeration cycle apparatus 100C, by controlling the first expansion valve 3 and the second expansion valve 57 when the stop signal is received without increasing the size of the accumulator 5B, the oil flowing into the compressor 1 at the next start-up is controlled. can be adjusted, and the reliability of the compressor 1 can be improved.

Embodiment 6.
<Circuit Configuration of Refrigeration Cycle Device 100B>
FIG. 13 is a diagram showing the circuit configuration of a refrigeration cycle device 100D according to Embodiment 6. As shown in FIG. A refrigerating cycle device 100</b>D of the sixth embodiment differs from the refrigerating cycle device 100 of the first embodiment in that a four-way valve 6 is provided on the refrigerant discharge side of the compressor 1 . Other configurations are the same as those of the refrigeration cycle apparatus 100 of the first embodiment. In the following description, points different from the first embodiment are mainly described.

The four-way valve 6 switches the direction in which the refrigerant discharged from the compressor 1 flows through the flow path by changing between the first state and the second state. In FIG. 13, the solid line indicated by the four-way valve 6 is the same as the flow path of the refrigeration cycle apparatus 100 of the first embodiment. By controlling the four-way valve 6, the control device 10 can switch from the flow path indicated by the solid line to the flow path indicated by the broken line.

In the refrigeration cycle device 100D, during cooling operation in which the flow path is switched to that indicated by the dashed line, the refrigerant flows through the compressor 1, the second heat exchanger 4, the first expansion valve 3, the first heat exchanger 2, and the accumulator 5 in this order. circulate. A configuration using such a four-way valve 6 can also be applied to the second to fifth embodiments.

<Summary>
The present disclosure relates to an accumulator 5 installed between a second heat exchanger 4 that is an evaporator of a refrigeration cycle device 100 and a refrigerant suction side of a compressor 1 . The accumulator 5 includes a container 51 for storing refrigerant, an inflow pipe 52 for inflowing the refrigerant into the container 51, an outflow pipe 53 for flowing the refrigerant out of the container 51, and an opening for sucking oil. It is provided with an oil return section 54 provided, and a decompression pipe 56 as a decompression device for decompressing the refrigerant. A decompression pipe 56 and an oil return portion 54 are arranged on the outflow pipe 53 in the accumulator 5 .

Preferably, the decompression device is configured with a decompression pipe 56 having a smaller diameter than the outflow pipe. The accumulator 5 is arranged in the order of the decompression pipe 56 and the oil return portion 54 on the outflow pipe 53 with respect to the flow direction of the refrigerant.

Preferably, the oil return portion includes a first oil return portion 54A and a second oil return portion 54B. The decompression device is composed of a decompression pipe 56 having a diameter smaller than that of the outflow pipe 53 . The accumulator 5A is arranged on the outflow pipe 53 in the order of the first oil return portion 54A, the decompression pipe 56, and the second oil return portion 54B with respect to the flow direction of the refrigerant.

Preferably, the decompression device is composed of a second expansion valve 57 whose degree of opening is adjustable. The accumulator 5B is arranged in the order of the second expansion valve 57 and the oil return portion 54 on the outflow pipe 53 with respect to the flow direction of the refrigerant.

The present disclosure relates to a refrigeration cycle device 100A including an accumulator 5B. The refrigeration cycle device 100A includes a compressor 1, a first heat exchanger 2, a second heat exchanger 4, a first expansion valve 3, and for measuring the discharge superheat degree of the refrigerant discharged from the compressor 1. and a control device 10 for controlling the degree of opening of the second expansion valve 57 . When the second heat exchanger 4 functions as an evaporator, refrigerant flows through the compressor 1, the first heat exchanger 2, the first expansion valve 3, the second heat exchanger 4, and the accumulator 5B in this order. The control device 10 controls the degree of opening of the second expansion valve 57 according to the degree of discharge superheat of the refrigerant obtained from the value of the discharge superheat degree sensor 61 .

The present disclosure relates to a refrigeration cycle device 100B having an accumulator 5B. The refrigeration cycle device 100B includes a compressor 1, a first heat exchanger 2, a second heat exchanger 4, a first expansion valve 3, and a second sensor for measuring the state of oil in the compressor 1. and a controller 10 that controls the degree of opening of the second expansion valve 57 . When the second heat exchanger 4 functions as an evaporator, refrigerant flows through the compressor 1, the first heat exchanger 2, the first expansion valve 3, the second heat exchanger 4, and the accumulator 5B in this order. The control device 10 controls the degree of opening of the second expansion valve 57 according to the state of the oil detected by the oil concentration sensor 62 .

The present disclosure relates to a refrigeration cycle device 100C including an accumulator 5B. The refrigeration cycle device 100C includes a compressor 1, a first heat exchanger 2, a second heat exchanger 4, a first expansion valve 3, and a first heat exchanger for measuring the degree of suction superheat of the refrigerant flowing into the accumulator 5B. An intake superheat sensor 63 as a three-sensor and a control device 10 for controlling the opening degrees of the first expansion valve 3 and the second expansion valve 57 are provided. When the second heat exchanger 4 functions as an evaporator, refrigerant flows through the compressor 1, the first heat exchanger 2, the first expansion valve 3, the second heat exchanger 4, and the accumulator 5B in this order. After receiving the stop signal of the compressor 1, the control device 10 increases the degree of opening of the second expansion valve 57 from before the stop of the compressor 1, and increases the suction superheat of the refrigerant obtained from the value of the suction superheat sensor 63. The degree of opening of the first expansion valve 3 is controlled according to the degree.

The present disclosure relates to a refrigeration cycle device 100 including an accumulator 5. The refrigeration cycle device 100 includes a compressor 1 , a first heat exchanger 2 , a second heat exchanger 4 and a first expansion valve 3 . When the second heat exchanger 4 functions as an evaporator, refrigerant flows through the compressor 1, the first heat exchanger 2, the first expansion valve 3, the second heat exchanger 4, and the accumulator 5 in this order.

The

accumulators

5, 5A, and 5B of the present embodiment can flow an appropriate amount of oil into the compressor 1 by using the small accumulator 5 with the above configuration. Refrigerating

cycle apparatuses

100 , 100 A, 100 B, and 100 C of the present embodiment can be configured as a refrigerant circuit in which an appropriate amount of oil flows into compressor 1 with small accumulator 5 by providing the above configuration.

<Modification>
In Embodiment 1, the accumulator 5 may appropriately change the size of the opening of the oil return portion 54 and the size of the diameter of the decompression pipe according to the flow rate of the refrigerant.

In Embodiment 2, three or more openings may be formed as the oil return portions. Thus, the number of oil return sections can be changed according to the flow rate. The accumulator 5A may have openings of different sizes for each of the plurality of oil return portions. The accumulator 5</b>A may be provided with a pressure reducing pipe 56 between each of the plurality of oil return portions, or the diameter of each of the plurality of pressure reducing pipes 56 may be changed.

In Embodiment 5, the suction superheat sensor 63 is provided between the second heat exchanger 4 and the accumulator 5B. The suction superheat sensor 63 may be provided between the accumulator 5B and the compressor 1 .

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

1 compressor, 2 first heat exchanger, 3 first expansion valve, 4 second heat exchanger, 5, 5A, 5B accumulator, 6 four-way valve, 10 control device, 51 container, 52 inflow pipe, 53 outflow pipe, 54, 54A, 54B Oil return section, 56 Decompression pipe, 57 Second expansion valve, 61 Discharge superheat sensor, 62 Oil concentration sensor, 63 Suction superheat sensor, 100, 100A, 100B, 100C, 100D Refrigeration cycle device.

Claims

An accumulator installed between the evaporator of the refrigeration cycle device and the refrigerant suction side of the compressor,
a container for storing a refrigerant;
an inflow pipe for inflowing a refrigerant into the container;
an outflow pipe for causing the refrigerant to flow out of the container;
an oil return section provided with an opening for sucking oil;
a decompression device that decompresses the refrigerant,
The accumulator, wherein the decompression device and the oil return section are arranged on the outflow pipe.
The decompression device is composed of a decompression pipe having a smaller diameter than the outflow pipe,
The accumulator according to claim 1, wherein the accumulator is arranged on the outflow pipe in the order of the pressure reduction pipe and the oil return portion with respect to the flow direction of the refrigerant.
The oil return section includes a first oil return section and a second oil return section,
The decompression device is composed of a decompression pipe having a smaller diameter than the outflow pipe,
The accumulator according to claim 1, wherein the accumulator is arranged on the outflow pipe in the order of the first oil return section, the decompression pipe, and the second oil return section with respect to the flow direction of the refrigerant.
The decompression device is composed of a second expansion valve whose opening can be adjusted,
The accumulator according to claim 1, wherein the accumulator is arranged on the outflow pipe in the order of the second expansion valve and the oil return portion with respect to the flow direction of the refrigerant.
A refrigeration cycle device comprising the accumulator according to claim 4,
the compressor;
a first heat exchanger;
a second heat exchanger;
a first expansion valve;
a first sensor for measuring the degree of discharge superheat of the refrigerant discharged from the compressor;
a control device that controls the degree of opening of the second expansion valve,
when the second heat exchanger functions as the evaporator, the refrigerant flows in the order of the compressor, the first heat exchanger, the first expansion valve, the second heat exchanger, and the accumulator;
The refrigeration cycle device, wherein the control device controls the degree of opening of the second expansion valve in accordance with the degree of discharge superheat of the refrigerant obtained from the value of the first sensor.
A refrigeration cycle device comprising the accumulator according to claim 4,
the compressor;
a first heat exchanger;
a second heat exchanger;
a first expansion valve;
a second sensor for measuring the state of oil in the compressor;
a control device that controls the degree of opening of the second expansion valve,
when the second heat exchanger functions as the evaporator, the refrigerant flows in the order of the compressor, the first heat exchanger, the first expansion valve, the second heat exchanger, and the accumulator;
The refrigeration cycle device, wherein the control device controls the degree of opening of the second expansion valve according to the state of the oil detected by the second sensor.
A refrigeration cycle device comprising the accumulator according to claim 4,
the compressor;
a first heat exchanger;
a second heat exchanger;
a first expansion valve;
a third sensor for measuring the degree of suction superheat of refrigerant flowing into the accumulator;
a control device for controlling opening degrees of the first expansion valve and the second expansion valve;
when the second heat exchanger functions as the evaporator, the refrigerant flows in the order of the compressor, the first heat exchanger, the first expansion valve, the second heat exchanger, and the accumulator;
After receiving the stop signal of the compressor, the control device increases the degree of opening of the second expansion valve more than before the stop of the compressor, and the degree of suction superheat of the refrigerant obtained from the value of the third sensor. a refrigeration cycle device that controls the degree of opening of the first expansion valve according to .
A refrigeration cycle device comprising the accumulator according to any one of claims 1 to 3,
the compressor;
a first heat exchanger;
a second heat exchanger;
a first expansion valve;
A refrigeration cycle in which refrigerant flows in order of the compressor, the first heat exchanger, the first expansion valve, the second heat exchanger, and the accumulator when the second heat exchanger functions as the evaporator. Device.