WO2017221384A1

WO2017221384A1 - Refrigeration and air conditioning device

Info

Publication number: WO2017221384A1
Application number: PCT/JP2016/068704
Authority: WO
Inventors: 貴司久保; 光史新海; 慎一浅井
Original assignee: 三菱電機株式会社
Priority date: 2016-06-23
Filing date: 2016-06-23
Publication date: 2017-12-28
Also published as: JPWO2017221384A1; JP6618622B2

Abstract

A refrigeration and air conditioning device is provided with: a refrigeration cycle device in which a compressor, a condenser, a solenoid valve, an expansion valve, and an evaporator are annularly connected by piping; and a control device, wherein the control device is provided with an expansion valve control unit for closing the expansion valve at the time of a pump-down stop process, and a solenoid valve control unit for closing the solenoid valve after the expansion valve is completely closed at the time of the pump-down stop process.

Description

Refrigeration air conditioner

The present invention relates to a refrigeration air conditioner that suppresses an impact pressure caused by a liquid shock that is instantaneously generated when the compressor is restarted.

Some conventional refrigeration air conditioners include a refrigeration cycle device in which a compressor, a condenser, a solenoid valve, an expansion valve, and an evaporator are sequentially connected in a ring shape with a pipe, and the refrigerant circulates. When the compressor is restarted, the pressure in the piping upstream of the solenoid valve is higher than that in the piping downstream of the solenoid valve due to the pump down stop process. (Referred to as front and rear solenoid valves). Due to the difference in pressure, the liquid refrigerant in the piping on the upstream side of the solenoid valve collides with the expansion valve on the downstream side of the solenoid valve at the same time as opening the solenoid valve (hereinafter referred to as “liquid shock”).

When this liquid shock occurs, the expansion valve and piping vibrate due to the impact pressure when the liquid refrigerant collides with the expansion valve, and if the impact pressure is high, they may be damaged. For example, if the refrigeration air conditioner is used to cool a refrigerated warehouse, if the expansion valve breaks, the expansion process in the refrigeration cycle device cannot be performed normally, causing the temperature in the warehouse to rise and the quality of the object to be cooled Cause a drop. In addition, abnormal sounds and abnormal vibrations may be generated.

Also, even if the impact pressure due to the liquid shock is small, if the compressor is frequently started and stopped, the piping may be fatigued and broken, causing refrigerant leakage. This refrigerant leakage has a great influence from the viewpoint of protecting the global environment.

Therefore, a technique for suppressing the impact pressure due to the liquid shock generated when the compressor of the refrigeration air conditioner is started has been proposed (see, for example, Patent Document 1 and Patent Document 2).

In Patent Document 1, a bypass circuit pipe having a pressure equalizing solenoid valve connected so as to bypass the pipes before and after the solenoid valve is separately provided, and the bypass circuit side precedes the opening of the solenoid valve when the refrigeration air conditioner is started. The pressure equalizing solenoid valve is opened, and the liquid refrigerant in the piping on the upstream side of the solenoid valve is made to flow little by little to the downstream side of the solenoid valve, thereby reducing the pressure difference before and after the solenoid valve. The impact pressure is suppressed.

Further, in Patent Document 2, the space volume of the refrigerant flow path between the opening / closing part of the electromagnetic valve and the flow rate adjusting part of the expansion valve is limited, and the expansion valve is not activated before the refrigerant flowing in from the upstream side of the electromagnetic valve gains momentum. The shock pressure due to the liquid shock is suppressed.

Japanese Patent Laid-Open No. 11-325654 JP 2012-215309 A

Since Patent Document 1 and Patent Document 2 need to add a bypass circuit or limit the space volume between the solenoid valve and the expansion valve, it is necessary to have a pipe shape specialized for liquid shock countermeasures. There is. Moreover, when the pipe diameter of the bypass circuit is too large, the effect of suppressing the impact pressure due to the liquid shock may be reduced, and there is a problem that selection of the pipe is difficult.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a refrigerating and air-conditioning apparatus capable of suppressing impact pressure due to a liquid shock.

A refrigerating and air-conditioning apparatus according to the present invention includes a compressor, a condenser, a solenoid valve, an expansion valve, and a refrigeration cycle apparatus in which an evaporator is annularly connected by piping, and a control device, and the control device includes: An expansion valve control unit that closes the expansion valve during the pump down stop process, and an electromagnetic valve control unit that closes the electromagnetic valve after the expansion valve is fully closed during the pump down stop process. It is.

According to the refrigerating and air-conditioning apparatus according to the present invention, in the pump down stop process, by closing the solenoid valve after the expansion valve is fully closed, the pipe in the upstream side of the solenoid valve and the downstream side of the solenoid valve are closed. An equivalent high-pressure liquid refrigerant is accumulated in both of the pipes, and the impact pressure due to a liquid shock when the compressor is restarted can be suppressed.

It is the schematic which showed the refrigerating cycle apparatus of the refrigerating air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a functional block diagram of the control apparatus of the refrigeration air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the flow of the control processing at the time of the pump down stop process of the conventional refrigeration air conditioner. It is a time chart which shows the flow of the control processing at the time of the pump down stop process of the conventional refrigeration air conditioner. It is a flowchart which shows the flow of the control processing at the time of the pump down stop process of the refrigeration air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a time chart which shows the flow of the control processing at the time of the pump down stop process of the refrigeration air conditioner concerning Embodiment 1 of this invention. It is the schematic which shows the refrigeration cycle apparatus of the refrigeration air conditioning apparatus which concerns on Embodiment 2 of this invention. It is a functional block diagram of the control apparatus of the refrigeration air conditioning apparatus which concerns on Embodiment 2 of this invention. It is a flowchart which shows the flow of the control processing at the time of the pump down stop process of the refrigeration air conditioning apparatus which concerns on Embodiment 2 of this invention. It is a time chart which shows the flow of the control processing at the time of the pump down stop process of the refrigeration air conditioner which concerns on Embodiment 2 of this invention, and a stop. It is the schematic which shows another example of the refrigerating-cycle apparatus of the refrigerating and air-conditioning apparatus of FIG. It is a flowchart which shows the flow of the control processing which adjusts the pressure difference before and behind an electromagnetic valve at the time of the stop of the refrigerating air conditioner which concerns on Embodiment 3 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below. Moreover, in the following drawings, the relationship of the size of each component may be different from the actual one.

Embodiment 1 FIG.
1 is a schematic diagram showing a refrigeration cycle apparatus of a refrigeration air-conditioning apparatus according to Embodiment 1 of the present invention.
As shown in FIG. 1, the refrigerating and air-conditioning apparatus according to Embodiment 1 includes a compressor 1, a condenser 2, a solenoid valve 3, an expansion valve 4, and an evaporator 5. The compressor 1 and the condenser 2 are connected by a first pipe 11, and the condenser 2 and the electromagnetic valve 3 are connected by a second pipe 12. The solenoid valve 3 and the expansion valve 4 are connected by a third pipe 13, the expansion valve 4 and the evaporator 5 are connected by a fourth pipe 14, and the evaporator 5 and the compressor 1 are connected by a fifth pipe 15. ing. And each component is connected cyclically | annularly by each piping, and the refrigerating-cycle apparatus with which the refrigerant | coolant enclosed inside circulates is comprised.

In addition, the expansion valve 4 shall use the expansion mechanism which can adjust an opening degree arbitrarily, for example, is an electronic expansion valve.
Moreover, the 1st piping 11, the 2nd piping 12, the 3rd piping 13, the 4th piping 14, and the 5th piping 15 are not piping shapes specialized for the liquid shock countermeasure, but are normal piping shapes.
Moreover, the refrigerating and air-conditioning apparatus according to Embodiment 1 may include components provided to adjust the state of the refrigeration cycle apparatus such as an oil separator, a liquid receiver, and an accumulator, for example.

The refrigerant sealed in the refrigeration cycle apparatus is compressed by the compressor 1 to become a high-temperature and high-pressure gas refrigerant and discharged to the first pipe 11. Thereafter, heat is exchanged with air, water, and the like by the condenser 2 to condense and become a high-pressure liquid refrigerant, which passes through the second pipe 12 and the electromagnetic valve 3. The liquid refrigerant that has passed through the electromagnetic valve 3 passes through the third pipe 13, is decompressed by the expansion valve 4, and changes its state to a low-pressure gas-liquid two-phase refrigerant in which liquid and gas are mixed. Thereafter, the low-pressure gas-liquid two-phase refrigerant passes through the fourth pipe 14 and passes through the evaporator 5. In the evaporator 5, heat is exchanged with air, water, brine, and the like to evaporate, a low-pressure gas refrigerant passes through the fifth pipe 15, and is sucked into the compressor 1 again.

FIG. 2 is a functional block diagram of the control device 50 of the refrigeration air conditioner according to Embodiment 1 of the present invention.
Moreover, as shown in FIG. 2, the refrigerating and air-conditioning apparatus according to the first embodiment includes a control device 50 that controls the operation of each component. The refrigerating and air-conditioning apparatus is configured so that the control device 50 can adjust the operation start and stop timing of each component.
The control device 50 includes, for example, dedicated hardware or a CPU (also referred to as a central processing unit, a central processing device, a processing device, an arithmetic device, a microprocessor, a microcomputer, or a processor) that executes a program stored in a memory. Is done.

The control device 50 includes a command receiving unit 51 that receives a stop command or a start command from the outside, a compressor control unit 52 that controls the compressor 1, an electromagnetic valve control unit 53 that controls the electromagnetic valve 3, and an expansion valve. 4, an expansion valve control unit 54 that controls 4, a storage unit 55 that stores control information of each component, and a count unit 56 that counts time.

Further, the storage unit 55 stores a set time A from when the expansion valve 4 starts to be closed until it is fully closed, and a set time B from when the set time A elapses until the solenoid valve 3 is closed. ing.

Note that the set time A includes the closing speed V that is unique to the expansion valve 4 and moves in the closing direction, the opening degree of the expansion valve 4 fully opened, or the opening degree of the expansion valve 4 at the start of the pump down stop process. A value calculated from X is set. In addition, the set time B may be set with a margin when a delay occurs in the closing speed V of the expansion valve 4 and the expansion valve 4 is not fully closed within the set time A.

The control device 50 performs a pump down stop process. The pump down stop process is to stop the refrigeration air conditioner, close the solenoid valve 3 before stopping the compressor 1, then operate the compressor 1 with a low capacity for a certain period of time, and compress from the downstream side of the solenoid valve 3. The refrigerant up to the suction port of the machine 1, that is, the refrigerant in the third pipe 13, the expansion valve 4, the fourth pipe 14, the evaporator 5, and the fifth pipe 15 flows to the downstream side of the compressor 1. That is. Thereby, the pressure state of the refrigerant in the refrigeration cycle apparatus is partitioned with the electromagnetic valve 3 as a boundary.

FIG. 3 is a flowchart showing the flow of control processing during pump down stop processing of a conventional refrigeration air conditioner, and FIG. 4 is a time chart showing the flow of control processing during pump down stop processing of a conventional refrigeration air conditioning device. It is. In addition, the conventional refrigeration air conditioner shall be equipped with the same refrigeration cycle apparatus as this Embodiment 1. FIG.

Hereinafter, the control process at the time of the pump down stop process of the conventional refrigeration air conditioner will be described.
As shown in FIGS. 3 and 4, the conventional refrigeration air conditioner starts the pump down stop process after receiving the stop command (Yes in step S1), and immediately closes the solenoid valve 3 to close the inside of the refrigeration cycle apparatus. The pressure state of the third pipe 13, the expansion valve 4, the fourth pipe 14, the evaporator 5, and the fifth pipe 15 is reduced to a low pressure while the compressor 1 is partitioned to a certain capacity (step S2). The expansion valve 4 is gradually closed while adjusting (step S3), and after the expansion valve 4 is fully closed, the compressor 1 is stopped (step S4).

On the other hand, the value of the pressure difference ΔP before and after the solenoid valve 3 rises after starting the pump-down stop process as shown in FIG. 4, and becomes larger than the differential pressure value C at which the liquid shock occurs when the compressor 1 is stopped. .

Then, in order to receive the start command (Yes in step S5) and start the operation of the refrigerating and air-conditioning apparatus again, the compressor 1 is restarted and the electromagnetic valve 3 is opened (step S6). By doing so, the refrigerant circulates again in the refrigeration cycle apparatus, and the operation of the refrigeration air conditioner resumes.

Note that the liquid shock generally tends to increase the impact pressure as the pressure difference ΔP before and after the solenoid valve 3 increases. When the conventional pump-down stop process is performed, high-pressure liquid refrigerant is accumulated in the second pipe 12 upstream of the solenoid valve 3, whereas the third pipe 13 downstream of the solenoid valve 3 is Low-pressure gas refrigerant is accumulated, and a pressure difference ΔP larger than the differential pressure value C is generated before and after the electromagnetic valve 3 as shown in FIG.

Therefore, when the solenoid valve 3 is opened simultaneously with the restart of the compressor 1, the liquid refrigerant accumulated in the second pipe 12 upstream of the solenoid valve 3 due to the pressure difference ΔP is transferred to the third downstream side of the solenoid valve 3. It flows into the pipe 13 instantaneously. The liquid refrigerant instantaneously flowing into the third pipe 13 generates a large impact pressure on the components and pipes on the downstream side of the electromagnetic valve 3.

Therefore, the refrigerating and air-conditioning apparatus according to Embodiment 1 performs the closing operation of the expansion valve 4 after starting the pump-down stop process so as not to generate a large pressure difference ΔP before and after the electromagnetic valve 3. Start prior to closing.

FIG. 5 is a flowchart showing the flow of control processing during the pump-down stop process of the refrigeration air-conditioning apparatus according to Embodiment 1 of the present invention. FIG. 6 shows the refrigeration air-conditioning apparatus according to Embodiment 1 of the present invention. It is a time chart which shows the flow of the control processing at the time of a pump down stop process.
Hereinafter, the control process at the time of the pump down stop process of the refrigerating and air-conditioning apparatus according to Embodiment 1 will be described.
As shown in FIGS. 5 and 6, when the command receiving unit 51 receives a stop command (Yes in step S <b> 11), the refrigeration air conditioner starts a pump down stop process. After starting the pump down stop process, the expansion valve control unit 54 starts closing the expansion valve 4 at the closing speed V, and at the same time, the counting unit 56 starts counting the set time A (step S12). At this time, the expansion valve 4 is gradually closed at the closing speed V until it is fully closed.

Further, until the set time A elapses, the solenoid valve 3 is in an open state, so that the refrigerant flows from the second pipe 12 upstream of the solenoid valve 3 to the downstream side of the solenoid valve 3, A high-pressure liquid refrigerant equivalent to the second pipe 12 on the upstream side of the solenoid valve 3 can be stored in the three pipes 13. Here, considering the case where the closing speed V of the expansion valve 4 is delayed, the opening / closing operation timing is set so that the solenoid valve 3 is closed after the expansion valve 4 is fully closed by taking a margin of the set time B. Control.

That is, the count unit 56 starts counting the set time B when the set time A is counted (step S13). When the set time B is counted, the compressor control unit 52 stops the compressor 1 (step S14). After stopping the compressor 1, the solenoid valve control unit 53 closes the solenoid valve 3 (step S15).

On the other hand, the value of the pressure difference ΔP before and after the electromagnetic valve 3 temporarily rises and becomes larger than the differential pressure value C after starting the pump down stop process as shown in FIG. 6, but the expansion valve 4 is closed. After the start, it gradually descends, and after the expansion valve 4 is fully closed, becomes smaller than the differential pressure value C.

Thereafter, when the command receiving unit 51 receives the start command (Yes in Step S16), the compressor control unit 52 restarts the compressor 1 and at the same time, the electromagnetic valve control unit 53 opens the electromagnetic valve 3 ( Step S17).

As described above, the closing operation of the expansion valve 4 is started prior to the closing operation of the electromagnetic valve 3, and is closed over a certain time. After the expansion valve 4 is fully closed, the electromagnetic valve 3 is closed. . Thus, by starting to close the expansion valve 4 on the downstream side of the electromagnetic valve 3 in advance, high-pressure liquid refrigerant can be stored in the third pipe 13 between the electromagnetic valve 3 and the expansion valve 4. .

Thereby, a high-pressure liquid refrigerant can be stored in both the second pipe 12 upstream of the solenoid valve 3 and the third pipe 13 downstream of the solenoid valve 3. Since high-pressure liquid refrigerant is accumulated in both the second pipe 12 and the third pipe 13, the pressure difference ΔP before and after the solenoid valve 3 is suppressed to zero or a very small value as shown in FIG. Will be.

Even if the compressor 1 is restarted and the solenoid valve 3 is momentarily opened, the pressure difference ΔP before and after the solenoid valve 3 is kept small, so that the high-pressure liquid refrigerant in the second pipe 12 is The amount of instantaneous flow into the downstream side of the valve 3 can be suppressed.

As described above, the refrigerating and air-conditioning apparatus according to Embodiment 1 adjusts the value of the pressure difference ΔP before and after the electromagnetic valve 3 by controlling the timing of the opening / closing operation of the electromagnetic valve 3 and the expansion valve 4 with the control device 50. Then, an equivalent high-pressure liquid refrigerant is accumulated in both the second pipe 12 upstream of the solenoid valve 3 and the third pipe 13 downstream of the solenoid valve 3.

By doing so, the pressure difference ΔP before and after the solenoid valve 3 can be suppressed to zero or a very small value. As a result, the compressor 1 can be restarted when the pressure difference ΔP before and after the solenoid valve 3 is zero or a very small value, so that the shock pressure due to the liquid shock is suppressed without using a pipe shape specialized for liquid shock countermeasures. can do.

Embodiment 2. FIG.
Hereinafter, Embodiment 2 of the present invention will be described, but the description overlapping with Embodiment 1 will be omitted, and the same reference numerals will be given to the same or corresponding parts as those in Embodiment 1.

FIG. 7 is a schematic diagram showing a refrigeration cycle apparatus of a refrigeration air conditioning apparatus according to Embodiment 2 of the present invention, and FIG. 8 is a functional block of a control apparatus 50a of the refrigeration air conditioning apparatus according to Embodiment 2 of the present invention. FIG.

As shown in FIG. 7, in the refrigeration cycle apparatus of the refrigerating and air-conditioning apparatus according to Embodiment 2, the first pressure sensor 21 is connected to the second pipe 12 upstream of the electromagnetic valve 3, and the first pressure sensor 21 is downstream of the electromagnetic valve 3. A second pressure sensor 22 is provided in each of the three pipes 13. Further, as shown in FIG. 8, the control device 50a of the refrigerating and air-conditioning apparatus according to Embodiment 2 includes a pressure information acquisition unit 57 that acquires pressure information detected by the first pressure sensor 21 and the second pressure sensor 22. I have. Further, a differential pressure value C at which a fluid shock occurs and a first control target value D (<C) having a margin with respect to the differential pressure value C are set. Is remembered.

FIG. 9 is a flowchart showing a flow of control processing during the pump-down stop process of the refrigeration air conditioner according to Embodiment 2 of the present invention, and FIG. 10 shows the refrigeration air conditioner according to Embodiment 2 of the present invention. It is a time chart which shows the flow of the control processing at the time of a pump down stop process and a stop. FIG. 10 is also used in a third embodiment described later, and the second control target value E in FIG. 10 will be described later in the third embodiment.

Hereinafter, the control process at the time of the pump down stop process of the refrigeration air conditioner according to the second embodiment will be described.
As shown in FIGS. 9 and 10, in the refrigeration air conditioner, when the command receiving unit 51 receives a stop command (Yes in step S21), the expansion valve control unit 54 starts closing the expansion valve 4 (step S22). ). At this time, the solenoid valve control unit 53 continues the open state of the solenoid valve 3, and the refrigerant flows from the second pipe 12 on the upstream side of the solenoid valve 3 to the third pipe 13 on the downstream side of the solenoid valve 3. To do. As shown in FIG. 10, the pressure difference ΔP before and after the electromagnetic valve 3 temporarily rises from the differential pressure value C depending on the operation state of the compressor 1 and the opening state of the expansion valve 4 during the pump down stop process. Also grows. However, as the opening degree of the expansion valve 4 approaches full closure, the high-pressure liquid refrigerant flowing from the second pipe 12 upstream of the solenoid valve 3 is accumulated in the third pipe 13 downstream of the solenoid valve 3. The pressure difference ΔP before and after the solenoid valve 3 gradually decreases.

The pressure information acquisition unit 57 includes information related to the pressure P1 of the second pipe 12 upstream of the electromagnetic valve 3 detected by the first pressure sensor 21 and the third downstream of the electromagnetic valve 3 detected by the second pressure sensor 22. Information on the pressure P2 of the pipe 13 is acquired, and a pressure difference ΔP = | P1−P2 | is calculated from the pressures P1 and P2 (step S23).

The compressor control unit 52 stops the compressor 1 after the expansion valve 4 is fully closed (step S24).
The solenoid valve control unit 53 sets the first control target value D as the control target value of the pressure difference ΔP, and the first control target value D where the pressure difference ΔP before and after the solenoid valve 3 after receiving the stop command is smaller than the differential pressure value C. The electromagnetic valve 3 is closed at the timing below (Yes in step S25, step S26).

Thereafter, when the command receiving unit 51 receives the start command (Yes in step S27), the compressor control unit 52 restarts the compressor 1, and at the same time, the electromagnetic valve control unit 53 opens the electromagnetic valve 3 ( Step S28).

The timing for closing the solenoid valve 3 may be before the expansion valve 4 is fully closed. However, if the closing operation of the expansion valve 4 is stopped halfway, the downstream side of the solenoid valve 3 is closed. The high-pressure liquid refrigerant stored in the third pipe 13 may be sent to the fourth pipe 14 on the downstream side of the expansion valve 4, and the value of the pressure difference ΔP before and after the electromagnetic valve 3 may increase.

However, in order to suppress the impact pressure due to the liquid shock, it is necessary to store a high-pressure liquid refrigerant in the third pipe 13 on the downstream side of the solenoid valve 3 to suppress the pressure difference ΔP to zero or a very small value. Therefore, even when the solenoid valve 3 is closed before the expansion valve 4 is fully closed, the expansion valve control unit 54 continues the closing operation of the expansion valve 4 until the expansion valve 4 is fully closed.

Thus, the refrigerating and air-conditioning apparatus according to Embodiment 2 adjusts the value of the pressure difference ΔP before and after the electromagnetic valve 3 by controlling the timing of the opening / closing operation of the electromagnetic valve 3 and the expansion valve 4 with the control device 50. Then, an equivalent high-pressure liquid refrigerant is accumulated in both the second pipe 12 upstream of the solenoid valve 3 and the third pipe 13 downstream of the solenoid valve 3.

Note that the second piping on the upstream side of the solenoid valve 3 is controlled by controlling the timing of the opening and closing operations of the solenoid valve 3 and the expansion valve 4 so that the pressure difference ΔP is less than the differential pressure value C at which a fluid shock occurs. 12 and the third piping 13 on the downstream side of the solenoid valve 3 are in a state where the same high-pressure liquid refrigerant is accumulated.

Moreover, since the refrigerating and air-conditioning apparatus according to the second embodiment controls the opening / closing operation timing of the solenoid valve 3 and the expansion valve 4 using the pressures P1 and P2, the solenoid valve is compared with the first embodiment. 3 and the timing of the opening / closing operation of the expansion valve 4 can be accurately controlled. As a result, the impact pressure due to the liquid shock can be further suppressed.

FIG. 11 is a schematic diagram illustrating another example of the refrigeration cycle apparatus of the refrigeration air-conditioning apparatus of FIG.
As shown in FIG. 11, instead of providing the first pressure sensor 21 and the second pressure sensor 22 before and after the electromagnetic valve 3, a fine differential pressure switch 23 for detecting the pressure difference ΔP before and after the electromagnetic valve 3 is provided, The fine differential pressure switch 23 may send a signal to the control device 50 when the difference ΔP becomes a preset pressure difference.

Embodiment 3 FIG.
Hereinafter, Embodiment 3 of the present invention will be described, but the description overlapping with

Embodiments

1 and 2 will be omitted, and the same or corresponding parts as those in

Embodiments

1 and 2 will be denoted by the same reference numerals. .

In the refrigerating and air-conditioning apparatus according to the third embodiment, when the pressure balance around the solenoid valve 3 is lost, the solenoid valve 3 is opened and closed while the compressor 1 is stopped using the second control target value E. Then, control for adjusting the pressure difference ΔP before and after the electromagnetic valve 3 is performed to suppress the impact pressure due to the liquid shock.

In the third embodiment, as shown in FIG. 10, a differential pressure value C at which a fluid shock occurs and a first control target value D (<C) with a margin for the differential pressure value C are obtained. In addition, a second control target value E that is less than the differential pressure value C and larger than the first control target value D (D <E <C) is set, and the information is stored in the storage unit 55. Yes.

FIG. 12 is a flowchart showing a flow of control processing for adjusting the pressure difference ΔP before and after the electromagnetic valve 3 when the refrigerating and air-conditioning apparatus according to Embodiment 3 of the present invention is stopped.
Hereinafter, a control process for adjusting the pressure difference ΔP before and after the electromagnetic valve 3 when the refrigerating and air-conditioning apparatus according to Embodiment 3 is stopped will be described.
When the refrigerant gradually leaks from the expansion valve 4 to the fourth pipe 14 on the downstream side while the compressor 1 is stopped, the pressure in the third pipe 13 on the downstream side of the solenoid valve 3 decreases. On the other hand, the pressure in the second pipe 12 on the upstream side of the electromagnetic valve 3 is maintained because it is closed by the electromagnetic valve 3 having better closing performance than the expansion valve 4. Therefore, the pressure difference ΔP before and after the electromagnetic valve 3 gradually increases in proportion to the refrigerant leakage amount from the expansion valve 4.

Therefore, as shown in FIGS. 10 and 12, before the condition for generating the liquid shock is satisfied, that is, before the pressure difference ΔP before and after the electromagnetic valve 3 calculated by the pressure information acquisition unit 57 becomes equal to or higher than the differential pressure value C. When the second control target value E is reached (Yes in step S31 and step S32), the solenoid valve control unit 53 opens the solenoid valve 3 (step S33), and the second piping upstream of the solenoid valve 3 is opened. The high-pressure liquid refrigerant stored in 12 is sent to the third pipe 13 on the downstream side of the solenoid valve 3. When the electromagnetic valve 3 is opened, there is a concern about the occurrence of a fluid shock, but when the pressure difference ΔP before and after the electromagnetic valve 3 reaches the second control target value E, the differential pressure value C at which a fluid shock occurs. Therefore, the impact pressure can be kept small.

After the solenoid valve 3 is opened, the pressure difference ΔP before and after the solenoid valve 3 starts to decrease. Thereafter, when the pressure difference ΔP calculated by the pressure information acquisition unit 57 becomes equal to or less than the first control target value D (Yes in Step S34 and Step S35), the electromagnetic valve control unit 53 closes the electromagnetic valve 3 (Step S34). S36). Then, when the refrigerant leaks again from the expansion valve 4 to the fourth pipe 14 on the downstream side, the pressure balance before and after the solenoid valve 3 is lost, and the pressure difference ΔP before and after the solenoid valve 3 increases, When the pressure difference ΔP calculated by the information acquisition unit 57 becomes equal to or greater than the second control target value E (Yes in Step S31 and Step S32), the electromagnetic valve control unit 53 performs an operation of opening the electromagnetic valve 3 (Step S31). S33), the control device 50a performs adjustment so that the pressure difference ΔP before and after the solenoid valve 3 does not exceed the second control target value E.

As described above, the refrigerating and air-conditioning apparatus according to Embodiment 3 adjusts the value of the pressure difference ΔP before and after the solenoid valve 3 by controlling the timing of the opening / closing operation of the solenoid valve 3 with the control device 50. 3 in the second pipe 12 on the upstream side and the third pipe 13 on the downstream side of the solenoid valve 3 in a state where the same high-pressure liquid refrigerant is accumulated.

Even when the pressure balance before and after the solenoid valve 3 is lost while the compressor 1 is stopped and the pressure difference ΔP before and after the solenoid valve 3 is increased, the electromagnetic valve 3 is controlled by opening and closing the solenoid valve 3 while the compressor 1 is stopped. By suppressing the pressure difference before and after the valve 3 to a certain value or less, the impact pressure due to the liquid shock can be suppressed.

Note that refrigerant leakage may be detected by a refrigerant detection means (not shown) or the like. The refrigerant detection means is, for example, a semiconductor gas sensor that detects a change in resistance value that occurs when the metal oxide-semiconductor contacts the refrigerant gas as a refrigerant gas concentration in the air, and a non-detection that detects the amount of infrared rays absorbed by the gas. For example, a distributed infrared sensor.

1 compressor, 2 condenser, 3 solenoid valve, 4 expansion valve, 5 evaporator, 11 first piping, 12 second piping, 13 third piping, 14 fourth piping, 15 fifth piping, 21 first pressure sensor , 22 second pressure sensor, 23 fine differential pressure switch, 50 control device, 50a control device, 51 command receiving unit, 52 compressor control unit, 53 solenoid valve control unit, 54 expansion valve control unit, 55 storage unit, 56 counts , 57 Pressure information acquisition unit.

Claims

A compressor, a condenser, a solenoid valve, an expansion valve, and a refrigeration cycle device in which an evaporator is annularly connected by piping, and a control device,
The control device includes:
An expansion valve control unit for closing the expansion valve during the pump down stop process;
A refrigerating and air-conditioning apparatus comprising: a solenoid valve controller configured to close the solenoid valve after the expansion valve is fully closed during the pump down stop process.
The control device includes:
A storage unit that stores a set time A from the start of closing of the expansion valve until the valve is fully closed, and a set time B after the set time A has elapsed until the solenoid valve is closed;
A counter that starts counting the set time A at the same time as the expansion valve starts to close, and starts counting the set time B when the set time A is counted, and
The solenoid valve control unit
The refrigerating and air-conditioning apparatus according to claim 1, wherein when the counting unit finishes counting the set time B, the expansion valve is closed.
A first pressure sensor for detecting pressure upstream of the solenoid valve;
A second pressure sensor for detecting the pressure on the downstream side of the solenoid valve,
The storage unit stores a first control target value D that is smaller than the differential pressure value C at which fluid shock occurs, and has a margin for the differential pressure value C.
The control device includes:
A pressure information acquisition unit that acquires information on the pressure P1 detected by the first pressure sensor and information on the pressure P2 detected by the second pressure sensor and calculates a pressure difference ΔP by the pressure P1 and the pressure P2 is provided. ,
The solenoid valve control unit
The refrigerating and air-conditioning apparatus according to claim 2, wherein the solenoid valve is closed at a timing when the pressure difference ΔP reaches the first control target value D.
A differential pressure switch for detecting a pressure difference ΔP between the upstream side and the downstream side of the solenoid valve;
The storage unit stores a first control target value D that is smaller than the differential pressure value C at which fluid shock occurs, and has a margin for the differential pressure value C.
The control device includes:
A pressure information acquisition unit for acquiring information on the pressure difference ΔP detected by the differential pressure switch;
The solenoid valve control unit
The refrigerating and air-conditioning apparatus according to claim 2, wherein the solenoid valve is closed at a timing when the pressure difference ΔP reaches the first control target value D.
The storage unit stores a second control target value E that is less than the differential pressure value C and greater than the first control target value D,
When stopping
The solenoid valve control unit
When the pressure difference ΔP is greater than or equal to the second control target value E, the solenoid valve is opened,
The refrigerating and air-conditioning apparatus according to claim 3 or 4, wherein the solenoid valve is closed when the pressure difference ΔP becomes equal to or less than the first control target value D.