Refrigerating system capable of effectively stabilizing suction pressure of compressor

Abstract

According to the refrigerating system capable of effectively stabilizing the suction pressure of the compressor, the four connectors of the four-way valve are connected with an inlet and an outlet of the compressor, the plate heat exchanger and the air cooler correspondingly; a first communicating pipeline, a second communicating pipeline, a first throttling branch and a second throttling branch which are connected in parallel are arranged between the plate heat exchanger and the other port of the air cooler, and a first electromagnetic valve, a second electromagnetic valve, a third electromagnetic valve, a fourth electromagnetic valve, a fifth electromagnetic valve, a first electronic expansion valve, a thermostatic expansion valve and a capillary tube are arranged; a refrigeration cycle of the compressor, the four-way valve, the plate heat exchanger, the first electromagnetic valve, the second electromagnetic valve, the first electronic expansion valve, the air cooler, the four-way valve and the compressor is formed; and defrosting circulation of the compressor, the four-way valve, the air cooler, the third electromagnetic valve, the fourth electromagnetic valve, the first electronic expansion valve and / or the fifth electromagnetic valve, the capillary tube, the plate heat exchanger, the four-way valve and the compressor is carried out. The system ensures that the suction pressure of the compressor is stable by controlling the fourth and fifth electromagnetic valves.

Description

TECHNICAL FIELD

[0001] The utility model relates to refrigerating system technical field, concretely is a refrigerating system that can effectively stabilize compressor suction pressure. BACKGROUND

[0002] In the refrigerating system of the cold storage, because the temperature of the inside environment of the cold storage is low, the relative humidity is big, when the air containing water vapor contacts the surface of the cold fan whose temperature is lower than the dew point temperature, the water vapor will condense into frost and adhere on the fan, and the higher the humidity of the air in the cold storage, the more serious the frost phenomenon.

[0003] The thermal conductivity of the frost layer is far lower than metal, when the surface of the cold fan is frosted, the thermal resistance increases, which will lead to the decrease of the ability of the cold fan to absorb heat from the cold storage, reduce the refrigeration efficiency of the system, at the same time, to reach the set temperature in the cold storage, the refrigeration system needs to run for a longer time, and the energy consumption will also increase accordingly. Secondly, the existence of the frost layer will cause the air circulation of the cold fan to be blocked, cause the temperature distribution in the cold storage to be uneven, the local temperature to be too high or too low, and affect the quality of the refrigerated goods.

[0004] The existing defrosting methods mainly include the following: manual defrosting, electric defrosting, water defrosting, hot gas defrosting, etc., wherein the manual defrosting refers to that after the refrigeration equipment stops running, the frost layer on the surface of the evaporator is removed by tools, which is commonly used in small refrigeration equipment (such as small refrigerators, refrigerators, etc.), but improper operation can easily damage the equipment, and labor is consumed. The electric defrosting refers to that an electric heating element is installed on the surface of the evaporator, when defrosting is needed, the electric heating element is powered on, and the frost layer is melted by the heat generated by the heating element, which is simple to operate but consumes additional electric energy, and the operation cost is relatively high. The water defrosting refers to that warm water is sprayed to the surface of the frost layer to melt it, which needs a special water supply and drainage system, and the equipment investment is large, and a large amount of spraying water will cause the humidity in the cold storage to increase greatly, which affects the stable temperature and humidity in the cold storage. In comparison, the hot gas defrosting uses the high-temperature refrigerant gas discharged by the compressor to introduce into the evaporator, so that the frost layer is melted by absorbing heat, which has a high temperature, can quickly provide a large amount of heat for the frost layer, and quickly melt the frost layer without consuming other energy and human resources, which reduces the defrosting cost, and under appropriate control measures, it is also more conducive to maintaining the stable temperature and humidity environment in the cold storage.

[0005] At present, the plate heat exchanger is used as the condenser in the refrigeration system of most cold storages, compared with the evaporative condenser, the plate heat exchanger has compact structure, small space occupation, light weight, and is convenient to install and use, at the same time, the plate heat exchanger has higher heat transfer efficiency and is more energy-saving.

[0006] The plate heat exchanger is internally stacked by a series of metal sheets with corrugated shape, and a plurality of narrow channels are formed between the metal sheets, in the hot gas defrosting mode, due to the small volume of the plate heat exchanger itself, the refrigerant capacity contained therein is small, and the response speed of the upstream thermal expansion valve is slow, the flow area is small, the efficiency of the plate heat exchanger for supplying liquid is low, and the liquid supply is small, so that the pressure in the plate heat exchanger is rapidly reduced during the hot gas defrosting of the system, even negative pressure occurs, the pressure fluctuation is large, and the service life of the compressor and the stable operation of the system are seriously affected. Practical new type content

[0007] To solve the technical problems in the above background art, the utility model provides a refrigeration system which can effectively stabilize the suction pressure of the compressor.

[0008] The utility model technical scheme is as follows:

[0009] A refrigeration system which can effectively stabilize the suction pressure of the compressor, comprising a compressor, a four-way valve, a plate heat exchanger and a cold air machine, the four interfaces of the four-way valve are connected with the inlet and outlet of the compressor and the a port of the plate heat exchanger and the b port of the cold air machine, and the b port of the plate heat exchanger is connected with the a port of the cold air machine.

[0010] The b port of the plate heat exchanger is connected with the a port of the cold air machine through a first electromagnetic valve, a second electromagnetic valve and a first electronic expansion valve in sequence, and is defined as a first communication pipeline, a second communication pipeline is branched out on the pipeline between the first electromagnetic valve and the second electromagnetic valve, and is connected with the pipeline between the first electronic expansion valve and the a port of the cold air machine, and a third electromagnetic valve is arranged on the second communication pipeline.

[0011] A throttling branch is branched out on the pipeline between the first electromagnetic valve and the b port of the plate heat exchanger, and is connected with the pipeline between the first electromagnetic valve and the second electromagnetic valve, the throttling branch comprises a first throttling branch and a second throttling branch connected in parallel, a fourth electromagnetic valve and a thermal expansion valve are connected in series on the first throttling branch, and a fifth electromagnetic valve and a capillary are connected in series on the second throttling branch.

[0012] A pressure sensor is arranged on the pipeline connected with the inlet of the compressor.

[0013] The refrigeration system of the application comprises a refrigeration mode and a defrosting mode, wherein,

[0014] In the refrigeration mode, the first solenoid valve, the second solenoid valve and the first electronic expansion valve are started, the third solenoid valve, the fourth solenoid valve and the fifth solenoid valve are closed, and the four-way valve is connected to the outlet of the compressor and the a port of the plate heat exchanger and connected to the b port of the air cooler. The refrigeration circuit is that the refrigerant is compressed into high-temperature and high-pressure refrigerant by the compressor, enters the a port of the plate heat exchanger from the outlet of the compressor through the four-way valve control, is cooled into low-temperature and high-pressure refrigerant by the plate heat exchanger, flows out from the b port of the plate heat exchanger, enters the a port of the air cooler through the first communication pipeline, i.e. in sequence through the first solenoid valve, the second solenoid valve and the first electronic expansion valve, evaporates and absorbs heat in the air cooler, flows out from the b port of the air cooler, flows into the compressor from the inlet of the compressor through the four-way valve, and completes a refrigeration cycle.

[0015] In the defrosting mode, the first solenoid valve, the second solenoid valve and the first electronic expansion valve are closed, the third solenoid valve is opened, and the fourth solenoid valve and / or the fifth solenoid valve is opened. The four-way valve is connected to the outlet of the compressor and the b port of the air cooler and connected to the a port of the plate heat exchanger. The defrosting circuit is that the refrigerant is compressed into high-temperature and high-pressure refrigerant by the compressor, enters the b port of the air cooler from the outlet of the compressor through the four-way valve control, defrosts the air cooler, flows out from the a port of the air cooler, enters the first communication pipeline through the third solenoid valve, and enters the throttling branch through the first communication pipeline, then enters the first throttling branch (i.e. in sequence through the fourth solenoid valve and the thermal expansion valve) and / or the second throttling branch (i.e. in sequence through the fifth solenoid valve and the capillary), enters the b port of the plate heat exchanger, cools down by the plate heat exchanger, flows out from the a port of the plate heat exchanger, flows into the compressor from the inlet of the compressor through the four-way valve control, and completes a refrigeration cycle.

[0016] In the defrosting mode, by controlling the communication of the first throttling branch and the second throttling branch, the flow of the refrigerant entering the plate heat exchanger is adjusted, so that the pressure is prevented from being reduced due to insufficient refrigerant supply in the plate heat exchanger, and the stability of the pressure in the suction pipe of the compressor is ensured.

[0017] Further, an economizer group is arranged on the first communication pipeline, the economizer group is located between the two ends of the throttling branch and is connected in parallel with the throttling branch, the economizer group comprises an economizer and a second electronic expansion valve, the economizer is provided with an a inlet and a b outlet connected in communication and a c inlet and a d outlet connected in communication, the a inlet is connected with the first solenoid valve, the b outlet is connected with the second solenoid valve, the compressor is provided with a supplementary air inlet, the d outlet of the economizer is connected with the supplementary air inlet of the compressor, and the c inlet is connected to the pipeline between the b outlet and the second solenoid valve through the second electronic expansion valve.

[0018] In the refrigeration mode, the refrigerant flowing out of the plate heat exchanger passes through the first electromagnetic valve, enters the economizer from the a inlet, and flows out from the b outlet, part of the refrigerant flowing out reenters the economizer from the c inlet of the economizer through the second electronic expansion valve, the refrigerant reentering the economizer exchanges heat with the refrigerant in the a and b passages of the economizer, and then flows out from the d outlet, enters the compressor from the air supplementing port, and mixes with the refrigerant entering the compressor from the inlet.

[0019] By arranging the economizer, the temperature of the refrigerant flowing into the cold air fan can be further reduced, and the refrigeration effect of the refrigeration system is improved.

[0020] In the defrosting mode, the refrigerant flowing out of the a port of the cold air fan passes through the second communication pipeline, first enters the economizer group through the first communication pipeline, and flows in the economizer group in the same way as in the refrigeration mode, except that part of the refrigerant flowing out from the b outlet of the economizer flows to the first throttling branch and / or the second throttling branch. The temperature of part of the refrigerant flowing to the throttling branch is reduced by the economizer, and the working load of the plate heat exchanger is reduced.

[0021] Further, a liquid accumulator is arranged on the first communication pipeline between the economizer group and the first electromagnetic valve, the first electromagnetic valve and the third electromagnetic valve are connected with the inlet of the liquid accumulator, the a inlet of the economizer is connected with the outlet of the liquid accumulator, and the liquid accumulator is used for storing refrigerant and buffering the flow of the refrigerant in the pipeline, and a certain amount of refrigerant can be stored in the liquid accumulator in advance to ensure sufficient flow of the refrigerant in the refrigeration system.

[0022] Further, an oil separator is arranged on the pipeline between the outlet of the compressor and the four-way valve to separate the lubricating oil carried by the gaseous refrigerant.

[0023] Further, a gas-liquid separator is arranged on the pipeline between the inlet of the compressor and the four-way valve to prevent liquid (lubricating oil or refrigerant) from impacting the compressor and ensure safe and normal operation of the compressor.

[0024] The refrigeration system provided by the utility model can effectively stabilize the suction pressure of the compressor, has the following advantages

[0025] Advantages:

[0026] 1. When the system is used to stabilize the suction pressure of the compressor, no additional control system is arranged outside the system, but the refrigerant in the system is reasonably utilized to control the flow of the refrigerant in the plate heat exchanger, so that the purpose of stabilizing the suction pressure of the compressor is achieved, the system is low in modification cost and convenient to maintain, the investment and operation cost of the equipment are greatly reduced while the suction pressure of the compressor is stabilized during defrosting of the system.

[0027] 2. This system provides three adjustment methods for stabilizing the compressor suction pressure during defrosting: the first and second throttling branches can be connected individually or simultaneously to ensure the reliability of the system's operation in defrosting mode. Furthermore, a pressure sensor is installed at the compressor's suction port, allowing for real-time selection of different adjustment methods based on the sensor readings. By coordinating the opening and closing of different valves and passages in the control system, the system achieves rapid and effective control of the compressor suction pressure during defrosting, ensuring normal system operation. Attached Figure Description

[0028] In the attached diagram:

[0029] Figure 1 This is a schematic diagram of a refrigeration system;

[0030] Figure 2 This is a schematic diagram of the voltage regulation method of a refrigeration system.

[0031] The components represented by the various reference numerals in the diagram are:

[0032] 1. Compressor; 2. Four-way valve; 3. Plate heat exchanger; 4. Air cooler; 5. First solenoid valve; 6. Second solenoid valve; 7. First electronic expansion valve; 8. Third solenoid valve; 9. Fourth solenoid valve; 10. Thermal expansion valve; 11. Fifth solenoid valve; 12. Capillary tube; 13. Economizer; 14. Second electronic expansion valve; 15. Liquid receiver; 16. Oil separator; 17. Gas-liquid separator. Detailed Implementation

[0033] Example 1

[0034] like Figure 1 As shown, this utility model embodiment provides a refrigeration system that can effectively stabilize the compressor suction pressure, including a compressor 1, a four-way valve 2, a plate heat exchanger 3, and a cooler 4. The four ports of the four-way valve 2 are respectively connected to the inlet and outlet of the compressor 1, the a port of the plate heat exchanger 3, and the b port of the cooler 4. The b port of the plate heat exchanger 3 is connected to the a port of the cooler 4.

[0035] The b port of the plate heat exchanger 3 is connected to the a port of the air cooler 4 in sequence through the first solenoid valve 5, the second solenoid valve 6 and the first electronic expansion valve 7, and is defined as the first connecting pipe. A second connecting pipe branches out from the pipe between the first solenoid valve 5 and the second solenoid valve 6 and connects to the pipe between the first electronic expansion valve 7 and the a port of the air cooler 4. A third solenoid valve 8 is provided on the second connecting pipe.

[0036] A throttling branch is branched from the pipeline between the first electromagnetic valve 5 and the b port of the plate heat exchanger 3, and is connected with the pipeline between the first electromagnetic valve 5 and the second electromagnetic valve 6, the throttling branch comprises a first throttling branch and a second throttling branch in parallel, the first throttling branch is in series with the fourth electromagnetic valve 9 and the thermal expansion valve 10, the second throttling branch is in series with the fifth electromagnetic valve 11 and the capillary tube 12, and the refrigerant can enter the plate heat exchanger 3 through the fourth electromagnetic valve 9 and the thermal expansion valve 10 and / or the fifth electromagnetic valve 11 and the capillary tube 12 in sequence.

[0037] A pressure sensor is arranged on the pipeline connected with the inlet of the compressor 1.

[0038] For the convenience of subsequent description, the four interfaces of the four-way valve 2 are marked as a, b, c and d, wherein the a interface is connected with the outlet of the compressor 1, the b interface is connected with the a port of the plate heat exchanger 3, the c interface is connected with the b port of the cold air machine 4, and the d interface is connected with the inlet of the compressor 1.

[0039] The refrigeration system of the embodiment comprises a refrigeration mode and a defrosting mode, wherein,

[0040] In the refrigeration mode, the first electromagnetic valve 5, the second electromagnetic valve 6 and the first electronic expansion valve 7 are started, the third electromagnetic valve 8, the fourth electromagnetic valve 9 and the fifth electromagnetic valve 11 are closed, the a and b interfaces of the four-way valve 2 are communicated to communicate the outlet of the compressor 1 with the a port of the plate heat exchanger 3, and the c and d interfaces of the four-way valve 2 are communicated to communicate the inlet of the compressor 1 with the b port of the cold air machine 4.

[0041] The refrigeration circuit is that the refrigerant is compressed into high-temperature and high-pressure refrigerant by the compressor 1, enters the plate heat exchanger 3 from the a port of the plate heat exchanger 3 through the control of the four-way valve 2, is cooled into low-temperature and high-pressure refrigerant by the plate heat exchanger 3, flows out from the b port of the plate heat exchanger 3, enters the a port of the cold air machine 4 through the first communication pipeline, i.e. through the first electromagnetic valve 5, the second electromagnetic valve 6 and the first electronic expansion valve 7 in sequence, evaporates and absorbs heat in the cold air machine 4, and flows out from the b port of the cold air machine 4, and then flows into the compressor 1 from the inlet of the compressor 1 through the four-way valve 2 to complete a refrigeration cycle.

[0042] In the defrosting mode, the first electromagnetic valve 5, the second electromagnetic valve 6 and the first electronic expansion valve 7 are closed, the third electromagnetic valve 8 is opened, and the fourth electromagnetic valve 9 and / or the fifth electromagnetic valve 11 are opened, the a and c interfaces of the four-way valve 2 are communicated to communicate the outlet of the compressor 1 with the b port of the cold air machine 4, and the b and d interfaces of the four-way valve 2 are communicated to communicate the inlet of the compressor 1 with the a port of the plate heat exchanger 3.

[0043] The defrosting circuit is that the refrigerant is compressed into high-temperature and high-pressure refrigerant by the compressor 1, enters the b port of the cold air machine 4 from the outlet of the compressor 1 through the four-way valve 2 control, flows out from the a port of the cold air machine 4 after defrosting the cold air machine 4, enters the first communication pipeline, that is, passes through the third electromagnetic valve 8, and enters the throttling branch pipeline by using the first communication pipeline, then enters the b port of the plate heat exchanger 3 through the first throttling branch pipeline, that is, passes through the fourth electromagnetic valve 9 and the thermal expansion valve 10 in turn, and / or the second throttling branch pipeline, that is, passes through the fifth electromagnetic valve 11 and the capillary tube 12 in turn, is cooled after passing through the plate heat exchanger 3, flows out from the a port of the plate heat exchanger 3, flows into the compressor 1 from the inlet of the compressor 1 through the four-way valve 2 control, and completes a refrigeration cycle.

[0044] In the defrosting mode, by controlling whether the first throttling branch pipeline and the second throttling branch pipeline are connected or not, the flow of the refrigerant entering the plate heat exchanger 3 is adjusted, so that the pressure in the plate heat exchanger 3 is prevented from being reduced due to insufficient refrigerant supply, and the stability of the pressure in the suction pipe of the compressor 1 is ensured.

[0045] In addition, an economizer group can also be arranged on the first communication pipeline, the economizer group is located between the two ends of the throttling branch pipeline as a whole, and is connected in parallel with the throttling branch pipeline, the refrigerant flowing out of the first electromagnetic valve 5 and the third electromagnetic valve 8 needs to flow into the economizer group for processing, and then flows to the second electromagnetic valve 6 or the throttling branch pipeline.

[0046] The economizer group specifically includes an economizer 13 and a second electronic expansion valve 14, the economizer 13 is provided with an a inlet and a b outlet connected in communication and a c inlet and a d outlet connected in communication, the a inlet is connected with the first electromagnetic valve 5, the b outlet is connected with the second electromagnetic valve 6, the compressor 1 is provided with a gas supplement port, the d outlet of the economizer 13 is connected with the gas supplement port of the compressor 1, and the c inlet is connected with the pipeline between the b outlet and the second electromagnetic valve 6 through the second electronic expansion valve 14. One end of the throttling branch pipeline and the second electronic expansion valve 14 are both connected with the pipeline between the second electromagnetic valve 6 and the economizer 13, but the connection position of the second electronic expansion valve 14 is closer to the economizer 13 than the connection position of the throttling branch pipeline. Then the refrigerant flowing out of the b outlet of the economizer 13 can be divided into a part entering the second electronic expansion valve 14 and another part entering the throttling branch pipeline, so as to ensure the cooling effect of the economizer 13.

[0047] The refrigerant enters the a inlet of the economizer 13, flows out of the b outlet, a part of the refrigerant flowing out of the b outlet reenters the economizer 13 from the c inlet of the economizer 13 through the second electronic expansion valve 14, and another part flows to the second electromagnetic valve 6. The refrigerant reentering the economizer 13 exchanges heat with the refrigerant in the a inlet and the b outlet of the economizer 13, then flows out of the d outlet, enters the compressor 1 from the gas supplement port of the compressor 1, and mixes with the refrigerant entering the compressor 1 from the inlet of the compressor 1.

[0048] By setting the economizer 13, the temperature of the refrigerant flowing into the cold air fan 4 or the throttling branch can be further reduced, the refrigeration effect of the refrigeration system can be improved, and the heat dissipation working load of the plate heat exchanger 3 can be reduced.

[0049] A liquid accumulator 15 can also be provided on the first communication pipeline between the economizer group and the first electromagnetic valve 5. The first electromagnetic valve 5 and the third electromagnetic valve 8 are both connected to the inlet of the liquid accumulator 15, and the a inlet of the economizer 13 is connected to the outlet of the liquid accumulator 15. The liquid accumulator 15 is used to store refrigerant as a buffer for the flow of refrigerant in the pipeline, and a certain amount of refrigerant can be pre-stored in the liquid accumulator 15 to ensure sufficient liquid flow of refrigerant in the refrigeration system.

[0050] An oil separator 16 can be provided on the pipeline between the outlet of the compressor 1 and the four-way valve 2 to separate the lubricating oil carried by the gaseous refrigerant.

[0051] A gas-liquid separator 17 can be provided on the pipeline between the inlet of the compressor 1 and the four-way valve 2 to prevent liquid (lubricating oil or refrigerant) from impacting the compressor 1 and ensure the safe and normal operation of the compressor 1.

[0052] The refrigeration system of the present embodiment also comprises a temperature sensor (not shown in the figure) for detecting the ambient temperature of the environment where the cold air fan 4 is located, and a pressure sensor (not shown in the figure) is provided at the b port of the cold air fan 4 to measure the pressure of the refrigerant in the cold air fan 4, and the temperature of the refrigerant in the cold air fan 4 is obtained by the corresponding relationship between the type of refrigerant and the pressure and temperature of the refrigerant.

[0053] The refrigeration system also comprises a controller (not shown in the figure) which is in communication connection with the first, second, third, fourth, fifth electromagnetic valves, the first and second electronic expansion valves, the four-way valve 2, the temperature sensor, and the two pressure sensors.

[0054] Embodiment Two

[0055] As shown in Figure 2 Based on the refrigeration system of embodiment one, the present embodiment provides a control method for using the refrigeration system, the steps are as follows:

[0056] S1, obtain the temperature of the environment where the cold air fan 4 is located and the temperature of the refrigerant in the cold air fan 4, and compare the two temperatures, if the temperature difference is less than the temperature setting value, start the refrigeration mode, otherwise, start the defrosting mode, and perform S2;

[0057] The temperature setting value can be set according to the actual operating conditions of the refrigeration system, and in the present embodiment, 10-15℃ is selected. In this step, when the defrosting mode is started, only the fourth electromagnetic valve 9 is opened in the two throttling branches, so that the first throttling branch is connected and the second throttling branch is closed, and the refrigerant flows through the thermal expansion valve 10.

[0058] S2, the refrigerant pressure at the suction end of the compressor 1 is obtained, and it is determined whether it is within the first preset pressure range. If yes, no operation is performed, otherwise, S3 is executed;

[0059] S3, among the two throttling branches, the fourth electromagnetic valve 9 is closed and the fifth electromagnetic valve 11 is opened, so that the first throttling branch is closed and the second throttling branch is connected, the refrigerant flows through the capillary tube 12, the flow of the refrigerant into the plate heat exchanger 3 is increased, and S4 is executed;

[0060] S4, the refrigerant pressure at the suction end of the compressor 1 is obtained, and it is determined whether it is within the second preset pressure range. If yes, no operation is performed, otherwise, S5 is executed;

[0061] S5, among the two throttling branches, the fourth electromagnetic valve 9 and the fifth electromagnetic valve 11 are opened, so that the two throttling branches are connected, the refrigerant passes through the thermal expansion valve 10 and the capillary tube 12 at the same time, and the flow of the refrigerant into the plate heat exchanger 3 is further increased, and S6 is executed;

[0062] S6, the refrigerant pressure at the suction end of the compressor 1 is obtained, and it is determined whether it is within the third preset pressure range. If yes, no operation is performed, otherwise, the operation of the compressor 1 is stopped.

[0063] In the embodiment, the first preset pressure range, the second preset pressure range and the third preset pressure range are three continuous pressure ranges, and the values of the three ranges decrease in turn. The preset pressure range can be set according to the actual working environment and working condition of the refrigeration system. In the embodiment, the first preset pressure range is 0.15-0.2 MPa, the second preset pressure range is 0.1-0.15 MPa, and the third preset pressure range is 0-0.1 MPa.

[0064] Example three

[0065] Based on the refrigeration system of example one, another control method for using the refrigeration system is provided in the embodiment, and the steps are basically the same as those of example two, except that after starting the defrosting mode, the refrigerant pressure at the suction end of the compressor 1 is obtained in real time, and is compared with the first preset pressure range, the second preset pressure range and the third preset pressure range at the same time,

[0066] If it is greater than the first preset pressure range, the fourth electromagnetic valve 9 and the fifth electromagnetic valve 11 are closed;

[0067] If it falls within the first preset pressure range, the fourth electromagnetic valve 9 is opened and the fifth electromagnetic valve 11 is closed;

[0068] If it falls within the second preset pressure range, the fourth electromagnetic valve 9 is closed and the fifth electromagnetic valve 11 is opened;

[0069] If falling into the third preset pressure range, the fourth electromagnetic valve 9 and the fifth electromagnetic valve 11 are opened;

[0070] If less than the third preset pressure range, the compressor 1 is stopped.

Claims

1. A refrigeration system capable of effectively stabilizing the suction pressure of a compressor, characterized by, It comprises a compressor (1), a four-way valve (2), a plate heat exchanger (3) and a cold air fan (4), four interfaces of the four-way valve (2) are connected with the inlet and outlet of the compressor (1) and the a port of the plate heat exchanger (3) and the b port of the cold air fan (4) respectively, and the b port of the plate heat exchanger (3) is connected with the a port of the cold air fan (4). The b port of the plate heat exchanger (3) is connected with the a port of the cold air fan (4) through the first electromagnetic valve (5), the second electromagnetic valve (6) and the first electronic expansion valve (7) in sequence and is defined as a first communication pipeline, a second communication pipeline is branched out from the pipeline between the first electromagnetic valve (5) and the second electromagnetic valve (6) and is connected with the pipeline between the first electronic expansion valve (7) and the a port of the cold air fan (4), and the third electromagnetic valve (8) is arranged on the second communication pipeline. A throttling branch is branched out from the pipeline between the first electromagnetic valve (5) and the b port of the plate heat exchanger (3) and is connected with the pipeline between the first electromagnetic valve (5) and the second electromagnetic valve (6), the throttling branch comprises a first throttling branch and a second throttling branch which are connected in parallel, the fourth electromagnetic valve (9) and the thermal expansion valve (10) are connected in series on the first throttling branch, and the fifth electromagnetic valve (11) and the capillary (12) are connected in series on the second throttling branch. A pressure sensor is arranged on the pipeline connected with the inlet of the compressor (1).

2. A refrigeration system capable of effectively stabilizing the suction pressure of a compressor as defined in claim 1, wherein An economizer group is further arranged on the first communication pipeline, the economizer group is located between the two ends of the throttling branch as a whole and is connected in parallel with the throttling branch, the economizer group comprises an economizer (13) and a second electronic expansion valve (14), the a inlet and the b outlet of the economizer (13) are connected in communication, the c inlet and the d outlet of the economizer (13) are connected in communication, the a inlet is connected with the first electromagnetic valve (5), the b outlet is connected with the second electromagnetic valve (6), a gas supplement port is arranged on the compressor (1), the d outlet of the economizer (13) is connected with the gas supplement port of the compressor (1), and the c inlet is connected on the pipeline between the b outlet and the second electromagnetic valve (6) through the second electronic expansion valve (14).

3. A refrigeration system capable of effectively stabilizing the suction pressure of a compressor as defined in claim 2, wherein A liquid accumulator (15) is further arranged on the first communication pipeline and is located between the economizer group and the first electromagnetic valve (5), the first electromagnetic valve (5) and the third electromagnetic valve (8) are both connected with the inlet of the liquid accumulator (15), and the a inlet of the economizer (13) is connected with the outlet of the liquid accumulator (15).

4. A refrigeration system capable of effectively stabilizing the suction pressure of a compressor as defined in claim 1, wherein An oil separator (16) is arranged on the pipeline between the outlet of the compressor (1) and the four-way valve (2).

5. A refrigeration system capable of effectively stabilizing the suction pressure of a compressor as defined in claim 1, wherein An air-liquid separator (17) is arranged on the pipeline between the inlet of the compressor (1) and the four-way valve (2).

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