A single-system refrigerator refrigeration system and a control method thereof

Abstract

The application relates to the technical field of refrigerator refrigeration, in particular to a novel single-system refrigerator refrigeration system and a control method thereof, which can solve the problem that, when defrosting, the residual liquid refrigerant of an evaporator absorbs the heat radiated to the evaporator surface by heating wires, prolongs the working time of the heating wires, greatly fluctuates the temperature of the refrigerator compartment, and influences the storage effect of food. The system comprises an electromagnetic three-way valve connected at the outlet of a condenser. The electromagnetic three-way valve is connected with the condenser through a first outlet; a second outlet of the electromagnetic three-way valve is connected with the inlet of a system throttling element; a third outlet of the electromagnetic three-way valve is connected with a bypass branch; the bypass branch is combined with a system main pipeline before the inlet of the evaporator; an electromagnetic cut-off valve is further arranged before the compressor and used for controlling the circulation of refrigerant between the evaporator outflow pipeline and the compressor; a pressure sensor is arranged at the outlet of the evaporator and used for sensing the refrigerant pressure at the outlet of the evaporator.

Description

Technical Field

[0001] The present application relates to the field of refrigerator refrigeration technology, and in particular to a single-system refrigerator refrigeration system and a control method thereof. Background Art

[0002] At present, electric heating wire is generally used for defrosting air-cooled frost-free refrigerators.

[0003] When the refrigerator is defrosting, the compressor stops and the refrigerator stops working, but about 20% of the liquid refrigerant is still stored in the refrigerator's evaporator. This part of the refrigerant will evaporate and absorb heat during the defrost stage, causing part of the heat radiated to the evaporator by the heating wire to be absorbed by the refrigerant in the evaporator, resulting in reduced defrosting efficiency, increased defrosting time, and increased temperature rise in the compartment. On the one hand, it affects the storage effect, and on the other hand, it increases energy consumption.

[0004] However, in the prior art, when the refrigerator is shut down for defrosting, the liquid refrigerant remaining in the evaporator absorbs the heat radiated from the heating wire to the evaporator surface. This heat is ineffective for defrosting and is considered heat loss. This phenomenon prolongs the working time of the heating wire and causes large temperature fluctuations in the refrigerator compartment, affecting the storage effect of food. On the other hand, it increases energy consumption and is not conducive to energy saving.

[0005] In addition, the refrigerator needs to be placed vertically during transportation. If it is placed upside down, the lubricating oil in the compressor will flow back into the evaporator. The oil cannot be returned quickly within a short period of time after startup, which will cause the compressor to lack oil and work abnormally. Moreover, the refrigerator itself is relatively high, and vertical transportation increases the difficulty and cost of transportation. Summary of the Invention

[0006] In order to solve the problem that in the prior art refrigerator, when defrosting, the residual liquid refrigerant in the evaporator absorbs the heat radiated from the heating wire to the evaporator surface, resulting in prolonged working time of the heating wire, large temperature fluctuations in the refrigerator compartment, and affecting the storage effect of food, the present application provides a single-system refrigerator refrigeration system and a control method thereof.

[0007] The embodiment of the present application is implemented as follows:

[0008] In a first aspect, the present application provides a single-system refrigerator refrigeration system, comprising an electromagnetic three-way valve connected to a condenser outlet. The electromagnetic three-way valve is connected to the condenser through a first outlet;

[0009] The second outlet of the electromagnetic three-way valve is connected to the inlet of the system throttling element, and the third outlet of the electromagnetic three-way valve is connected to the bypass branch, and the bypass branch merges with the system main pipeline before the evaporator inlet;

[0010] A solenoid stop valve is also provided in front of the compressor to control the flow of refrigerant between the evaporator outflow pipe and the compressor;

[0011] A pressure sensor is provided at the outlet of the evaporator to sense the refrigerant pressure at the outlet of the evaporator.

[0012] In a possible implementation, the throttling element includes a capillary tube or an expansion valve or a combination of the two.

[0013] In a second aspect, the present application provides a single-system refrigerator refrigeration system control method, which is applied to the single-system refrigerator refrigeration system described in any one of claims 1 or 2, including: a defrost control method and a transportation oil leakage prevention control method.

[0014] In a possible implementation, the defrosting method includes:

[0015] Refrigerators usually use the cumulative running time of the compressor after the last defrost is completed as the defrost control signal. The defrost cycle under the preset ambient temperature is T1. The time from the last defrost to the end of the last defrost when the compressor is about to stop after each refrigeration is Ta.

[0016] When the refrigerator is refrigerating and the compressor is about to stop, judge the size of T1 and Ta.<T1时,压缩机正常停机,当Ta> At T1, it enters the defrost mode, increases the compressor speed, and concentrates the refrigerant on the condenser.

[0017] In a possible implementation, when the pressure sensor at the evaporator outlet senses that the pressure Pa in the evaporator reaches a preset cut-off pressure P, the electromagnetic cut-off valve is closed, the compressor is shut down, the electric heating wire starts working, and defrosting begins.

[0018] In a possible implementation, the defrost time under normal working conditions is T2. After this time, the frost on the evaporator will be completely melted. The actual defrost start time is Tb. The maximum bypass defrost amount of refrigerant in the condenser is preset to m, and the frost remaining amount on the evaporator is preset to n. <m,差值为化霜余量,化霜时间节点为T3,T3<T2,当T3> At Tb, keep electric heating defrosting, when T3 <Tb时,关闭电加热丝,打开电磁三通阀旁通流路,打开电磁截止阀,制冷剂从出口流向沿旁通管流入蒸发器中,利用制冷剂显热融化余霜。

[0019] In one possible implementation, the total defrost time required from the start of defrost to the complete melting of frost on the evaporator after bypassing the refrigerant is preset to T4. When Tb>T4, the refrigerator defrost is completed, the third outlet flow direction of the electromagnetic three-way valve is closed, the second outlet flow direction is opened, and the refrigerator enters the normal refrigeration process.

[0020] In one possible implementation, the refrigeration operation of a single-system refrigerator includes:

[0021] The electromagnetic stop valve is opened, the electromagnetic three-way valve closes the third outlet flow direction and opens the second outlet flow direction. The refrigerant flowing out of the condenser passes through the electromagnetic three-way valve, is throttled and reduced in pressure by the throttling element, and then enters the evaporator. After flowing through the electromagnetic stop valve, it enters the compressor suction chamber.

[0022] In one possible implementation, the defrosting operation of a single-system refrigerator includes:

[0023] In the first stage, the first electromagnetic three-way valve is closed, the compressor increases the speed, and the refrigerant in the evaporator is concentrated in the condenser;

[0024] In the second stage, the electromagnetic stop valve is closed, the electromagnetic three-way valve is closed, the compressor stops, the electric heating wire starts working, and the evaporator starts to defrost;

[0025] In the third stage, after defrosting for a period of time, the electromagnetic three-way valve is opened, and the refrigerant flows from the third outlet through the bypass branch into the evaporator;

[0026] In the fourth stage, defrosting is completed, the flow direction of the third outlet of the electromagnetic three-way valve is closed, the flow direction of the second outlet is opened, and the electromagnetic stop valve is opened.

[0027] In a possible implementation, the transportation oil leakage prevention method includes:

[0028] A dedicated transport button is set on the refrigerator main control panel. During the production process, the refrigerator will be powered on and tested before leaving the factory. When the test shows that the refrigerator meets the delivery standards, the staff presses the button and the refrigerator enters the transport preparation mode.

[0029] After the refrigerator detects the transport preparation signal, the compressor stops working, the electromagnetic three-way valve closes, the electromagnetic stop valve opens, and the pressure sensor at the evaporator outlet detects the pressure Pd in ​​the pipeline;

[0030] The time interval of the detection time period is defined as Td. During the time interval Td, the difference between the two detection pressures Pd is defined as Pe. The critical minimum pressure difference between the compressor and the condenser when the lubricating oil flows out of the compressor after the electromagnetic shut-off valve is closed is defined as P3.

[0031] When it is detected that Pe≤P3, the refrigerator will automatically cut off the power and the electromagnetic stop valve will close.

[0032] The technical solution provided by this application can achieve at least the following beneficial effects:

[0033] The present application provides a single-system refrigerator refrigeration system and control method thereof. By adding an electromagnetic shut-off valve and an electromagnetic three-way valve to the refrigeration system, the valves are controlled to centrally collect refrigerant to the high-temperature side before defrosting, thereby reducing defrosting time and ineffective energy consumption, thereby reducing compartment fluctuations and saving energy.

[0034] In the later stage of defrosting, the residual frost on the evaporator is removed by the heat of the working medium on the high-temperature side, which reduces the working time of the electric heating wire, reduces energy consumption, and achieves energy-saving effects;

[0035] Through the shut-off effect of the shut-off valve during power outage and shutdown, the lubricating oil in the compressor cannot flow into the evaporator when the refrigerator is transported on its side, making it possible to transport the refrigerator on its side, enhancing transportation convenience and reducing transportation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0037] Figure 1 This is a structural diagram of a single-system refrigerator refrigeration system shown in an exemplary embodiment of the present application;

[0038] Figure 2 is a flow chart of a defrost control method according to an exemplary embodiment of the present application;

[0039] Figure 3 It is a flow chart of a transportation oil leakage prevention control method shown in an exemplary embodiment of the present application.

[0040] Reference numerals:

[0041] 1. Compressor; 11. Pressure sensor; 2. Condenser; 3. Solenoid three-way valve; 301. First outlet; 302. Second outlet; 303. Third outlet; 4. Throttling element; 5. Evaporator; 6. Solenoid stop valve. DETAILED DESCRIPTION

[0042] In order to make the purpose, implementation methods and advantages of the present application clearer, the exemplary implementation methods of the present application will be clearly and completely described below in conjunction with the drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only part of the embodiments of the present application, not all of the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0043] It should be noted that the brief descriptions of terms in this application are only for the purpose of facilitating the understanding of the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise specified, these terms should be understood according to their ordinary and usual meanings.

[0044] In the specification and claims of this application and the accompanying drawings, the terms "first," "second," "third," etc. are used to distinguish similar or similar objects or entities, and are not necessarily intended to limit a particular order or sequence, unless otherwise noted. It should be understood that the terms used in this manner are interchangeable under appropriate circumstances.

[0045] The terms "comprise," "include," and "have," and any variations thereof, are intended to cover but not exclude inclusion; for example, a product or device comprising a list of components is not necessarily limited to all the components expressly listed but may include other components not expressly listed or inherent to such product or device.

[0046] Before explaining a single-system refrigerator refrigeration system and control method provided in an embodiment of the present application, the application scenario and implementation environment of the embodiment of the present application are first introduced.

[0047] At present, electric heating wire is generally used for defrosting air-cooled frost-free refrigerators.

[0048] When the refrigerator is defrosting, the compressor stops and the refrigerator stops working, but about 20% of the liquid refrigerant is still stored in the refrigerator's evaporator. This part of the refrigerant will evaporate and absorb heat during the defrost stage, causing part of the heat radiated to the evaporator by the heating wire to be absorbed by the refrigerant in the evaporator, resulting in reduced defrosting efficiency, increased defrosting time, and increased temperature rise in the compartment. On the one hand, it affects the storage effect, and on the other hand, it increases energy consumption.

[0049] However, in the prior art, when the refrigerator is shut down for defrosting, the liquid refrigerant remaining in the evaporator absorbs the heat radiated from the heating wire to the evaporator surface. This heat is ineffective for defrosting and is considered heat loss. This phenomenon prolongs the working time of the heating wire and causes large temperature fluctuations in the refrigerator compartment, affecting the storage effect of food. On the other hand, it increases energy consumption and is not conducive to energy saving.

[0050] In addition, the refrigerator needs to be placed vertically during transportation. If it is placed upside down, the lubricating oil in the compressor will flow back into the evaporator. The oil cannot be returned quickly within a short period of time after startup, which will cause the compressor to lack oil and work abnormally. Moreover, the refrigerator itself is relatively high, and vertical transportation increases the difficulty and cost of transportation.

[0051] Based on this, the present application provides a single-system refrigerator refrigeration system and its control method. Through the cooperation of multiple valves and pipelines, the refrigerant in the evaporator is concentrated in the condenser before the start of defrosting, and the refrigerant in the condenser is bypassed to the evaporator in the second half of the defrosting stage, and the heat of the high-temperature refrigerant is used to assist defrosting, thereby reducing the energy consumption of defrosting and achieving the purpose of energy saving. The present invention evacuates the refrigerant in the evaporator before defrosting through the operation of the compressor, eliminates or substantially eliminates the absorption of defrosting heat by the vaporization of the refrigerant in the evaporator during the defrosting stage, improves the defrosting efficiency, shortens the defrosting time, reduces the energy consumption of the refrigerator, and reduces the temperature fluctuation in the room. In the late stage of electric heating defrosting, the refrigerant stored in the condenser is in a high-temperature and high-pressure state. When the bypass branch is opened, it will enter the evaporator under the drive of the pressure difference. The heat of the high-temperature refrigerant in the condenser is used to remove the residual frost on the evaporator, reducing the operating time of the defrosting heating wire, achieving the effect of energy saving. The valve control can also be used to solve the problem of oil leakage when the refrigerator is tilted during transportation, thereby reducing transportation costs.

[0052] Next, the technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems will be described in detail through embodiments and in conjunction with the accompanying drawings. The various embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, not all of them.

[0053] Figure 1 It is a structural diagram of a single-system refrigerator refrigeration system shown in an exemplary embodiment of the present application.

[0054] In an exemplary embodiment, Figure 1 As shown, a single-system refrigerator refrigeration system is provided. In this embodiment, the system includes an electromagnetic three-way valve 3 connected to the outlet of the condenser 2. The electromagnetic three-way valve 3 is connected to the condenser 2 through a first outlet 301;

[0055] The second outlet 302 of the electromagnetic three-way valve 3 is connected to the inlet of the system throttling element 4, and the third outlet 303 of the electromagnetic three-way valve 3 is connected to the bypass branch, which merges with the system main pipeline before the evaporator inlet;

[0056] A solenoid stop valve 6 is also provided in front of the compressor 1 to control the flow of refrigerant between the outflow pipe of the evaporator 5 and the compressor 1;

[0057] A pressure sensor 11 is provided at the outlet of the evaporator 5 for sensing the refrigerant pressure at the evaporator outlet.

[0058] In a possible implementation, the throttling element 4 includes a capillary tube or an expansion valve or a combination of the two.

[0059] It should be understood that, although the various steps in the flowcharts involved in the above-described embodiments are displayed in sequence according to the instructions, these steps are not necessarily executed in the order indicated. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the above-described embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0060] The present application also provides an embodiment of a single-system refrigerator refrigeration system control method.

[0061] In an exemplary embodiment, a single-system refrigerator refrigeration system control method includes a defrost control method and a transportation oil leakage prevention control method.

[0062] Figure 2 It is a flowchart of a defrost control method shown in an exemplary embodiment of the present application.

[0063] In one possible implementation, Figure 2 As shown in the figure, a single-system refrigerator has only one evaporator in its refrigeration system, and the defrost process is relatively simple. Refrigerators typically use the cumulative operating time of the compressor since the last defrost as the defrost control signal. When the refrigerator detects that defrost is needed, a valve is controlled to collect refrigerant in the condenser, where it is then heated by a heating element to defrost. When the residual frost level reaches the critical value (e.g., ≤20%), the electromagnetic three-way valve is controlled to bypass the refrigerant in the condenser, completing the melting of the residual frost on the evaporator surface.

[0064] The defrosting method includes:

[0065] Refrigerators usually use the cumulative running time of the compressor after the last defrost is completed as the defrost control signal. The defrost cycle under the preset ambient temperature is T1. The time from the last defrost to the end of the last defrost when the compressor is about to stop after each refrigeration is Ta.

[0066] When the refrigerator is cooling and compressor 1 is about to stop, judge the size of T1 and Ta.<T1时,压缩机1正常停机,当Ta> At T1, the system enters the defrost mode, increases the speed of compressor 1, and concentrates the refrigerant in condenser 2.

[0067] When the pressure sensor 11 at the outlet of the evaporator 5 senses that the pressure Pa in the evaporator 5 reaches the preset cut-off pressure P, the electromagnetic stop valve 6 is closed, the compressor 1 is shut down, the electric heating wire starts working, and defrosting begins.

[0068] Under normal working conditions, the defrost time is T2. After this time, the frost on the evaporator 5 will be completely melted. The actual defrost start time is Tb. The maximum bypass defrost amount of the refrigerant in the condenser 2 is preset to m, and the frost remaining amount on the evaporator 5 is preset to n. <m,差值为化霜余量,化霜时间节点为T3,T3<T2,当T3> At Tb, keep electric heating defrosting, when T3 <Tb时,关闭电加热丝,打开电磁三通阀3旁通流路,打开电磁截止阀6,制冷剂从出口流向沿旁通管流入蒸发器中,利用制冷剂显热融化余霜。

[0069] The total defrost time required from the start of defrost to the complete melting of frost on the evaporator after bypassing the refrigerant is preset to T4. When Tb>T4, the refrigerator defrost is completed, the third outlet 303 of the electromagnetic three-way valve 3 is closed, the second outlet 302 is opened, and the refrigerator enters the normal refrigeration process.

[0070] Figure 3 It is a flow chart of a transportation oil leakage prevention control method shown in an exemplary embodiment of the present application.

[0071] In one possible implementation, Figure 3 As shown, the electromagnetic shut-off valve in front of the compressor is a normally closed valve. When the refrigerator loses power, the electromagnetic shut-off valve automatically closes, preventing the refrigerant and lubricating oil in the pipeline from flowing into the evaporator. If a direct transport method is used during power outage, the refrigerant flow path from the compressor to the evaporator will be cut off. However, directly closing the shut-off valve will cause the evaporator side to be in a low-pressure state and the compressor and condenser sides to be in a high-pressure state. Due to the high-low pressure difference, the lubricating oil in the compressor will also flow out with the working fluid, causing oil leakage in the compressor, affecting normal operation after power is restored. Some embodiments of this application also propose a transport anti-leakage oil control method.

[0072] The transportation and oil leakage prevention methods include:

[0073] A dedicated transport button is set on the refrigerator main control panel. During the production process, the refrigerator will be powered on and tested before leaving the factory. When the test shows that the refrigerator meets the delivery standards, the staff presses the button and the refrigerator enters the transport preparation mode.

[0074] After the refrigerator detects the transport preparation signal, the compressor stops working, the electromagnetic three-way valve closes, the electromagnetic stop valve opens, and the pressure sensor at the evaporator outlet detects the pressure Pd in ​​the pipeline;

[0075] The time interval of the detection time period is defined as Td. During the time interval Td, the difference between the two detection pressures Pd is defined as Pe. The critical minimum pressure difference between the compressor and the condenser when the lubricating oil flows out of the compressor after the electromagnetic shut-off valve is closed is defined as P3.

[0076] When it is detected that Pe≤P3, the refrigerator will automatically cut off the power and the electromagnetic stop valve will close.

[0077] In a possible implementation, the specific operation of a single-system refrigerator refrigeration is as follows:

[0078] The electromagnetic stop valve 6 is opened, the electromagnetic three-way valve 3 closes the flow direction of the third outlet 303 and opens the flow direction of the second outlet 302. The refrigerant flowing out of the condenser 2 passes through the electromagnetic three-way valve 3, is throttled and reduced in pressure by the throttling element 4, and then enters the evaporator 5. After flowing through the electromagnetic stop valve 6, it enters the suction chamber of the compressor 1.

[0079] In a possible implementation, the specific operation of defrosting a single-system refrigerator is as follows:

[0080] In the first stage, the first electromagnetic three-way valve 3 is closed, the compressor 1 increases its speed, and the refrigerant in the evaporator 5 is concentrated in the condenser 2;

[0081] In the second stage, the electromagnetic stop valve 6 is closed, the electromagnetic three-way valve 3 is closed, the compressor 1 is shut down, the electric heating wire starts working, and the evaporator starts to defrost;

[0082] In the third stage, after defrosting for a period of time, the electromagnetic three-way valve 3 is opened, and the refrigerant flows from the third outlet 303 through the bypass branch into the evaporator 5;

[0083] In the fourth stage, the defrosting is completed, the flow direction of the third outlet 303 of the electromagnetic three-way valve 3 is closed, the flow direction of the second outlet 302 is opened, and the electromagnetic stop valve 6 is opened.

[0084] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The embodiments described above merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A single-system refrigerator refrigeration system control method, characterized in that: This method realizes refrigeration control based on a single-system refrigerator refrigeration system; the system includes an electromagnetic three-way valve connected to the outlet of the condenser; the electromagnetic three-way valve is connected to the condenser through the first outlet; The second outlet of the electromagnetic three-way valve is connected to the inlet of the system throttling element, the third outlet of the electromagnetic three-way valve is connected to a bypass branch, and the bypass branch converges with the main pipeline of the system in front of the inlet of the evaporator; An electromagnetic stop valve is also provided in front of the compressor to control the flow of refrigerant between the pipe flowing out of the evaporator and the compressor; A pressure sensor is provided at the outlet of the evaporator to sense the refrigerant pressure at the outlet of the evaporator; This method includes a defrost control method and a transportation anti-oil leakage control method; The defrost control method includes: The refrigerator usually uses the cumulative running time of the compressor since the last defrost completion as the defrost control signal. The defrost cycle at the preset current ambient temperature is T1, and the time Ta from the end of the last defrost to when the compressor is about to stop after each refrigeration cycle of the refrigerator; When the refrigerator is refrigerating and the compressor is about to stop, judge the magnitudes of T1 and Ta. When Ta < T1, the compressor stops normally. When Ta > T1, enter the defrost mode, the electromagnetic three-way valve closes, the compressor speed is increased, and the refrigerant is concentrated in the condenser; When the pressure sensor at the outlet of the evaporator senses that the pressure Pa in the evaporator reaches the preset cut-off pressure P, the electromagnetic stop valve is closed, the compressor stops, and the electric heating wire on the evaporator starts to work to start defrosting; Under normal conditions, the defrosting duration is T2. After this period of time, the frost on the evaporator will completely melt. The actual defrosting duration is Tb. The maximum bypass defrost amount of the refrigerant in the condenser is preset as m, the remaining frost amount on the evaporator is preset as n, n < m, and the difference is the defrosting margin. The preset bypass defrost time node is T3, T3 < T2. When T3 > Tb, keep the electric heating defrosting. When T3 < Tb, turn off the electric heating wire, open the bypass flow path of the electromagnetic three-way valve, open the electromagnetic stop valve, and the refrigerant flows from the outlet along the bypass pipe into the evaporator to melt the remaining frost using the sensible heat of the refrigerant.

2. The single-system refrigerator refrigeration system control method according to claim 1, characterized in that: The total defrosting duration T4 required for the frost on the evaporator to completely melt after bypassing the refrigerant from the start of defrosting is preset. When Tb > T4, the refrigerator defrosting is completed, the third outlet flow direction of the electromagnetic three-way valve is closed, the second outlet flow direction is opened, and the refrigerator enters the normal refrigeration process.

3. The single-system refrigerator refrigeration system control method according to claim 1, wherein: The operation of the single-system refrigerator refrigeration includes: The electromagnetic stop valve is opened, the third outlet flow direction of the electromagnetic three-way valve is closed, the second outlet flow direction is opened, the refrigerant flowing out of the condenser passes through the electromagnetic three-way valve, is throttled and depressurized by the throttling element and then enters the evaporator, and enters the suction chamber of the compressor after passing through the electromagnetic stop valve.

4. The single-system refrigerator refrigeration system control method according to claim 1, wherein: The operation of the single-system refrigerator defrosting includes: In the first stage, the electromagnetic three-way valve is closed, the compressor speed is increased, and the refrigerant in the evaporator is concentrated in the condenser; In the second stage, the electromagnetic stop valve is closed, the electromagnetic three-way valve is closed, the compressor stops, and the electric heating wire starts to work, and the evaporator starts to defrost; In the third stage, after defrosting for a period of time, the electromagnetic three-way valve is opened, and the refrigerant flows from the third outlet through the bypass branch into the evaporator; In the fourth stage, after defrosting is completed, the third outlet flow direction of the electromagnetic three-way valve is closed, the second outlet flow direction is opened, and the electromagnetic stop valve is opened.

5. The single-system refrigerator refrigeration system control method according to claim 1, wherein: The transportation and oil leakage prevention methods include: A dedicated transport button is set on the refrigerator main control panel. During the production process, the refrigerator will be powered on and tested before leaving the factory. When the test shows that the refrigerator meets the delivery standards, the staff presses the button and the refrigerator enters the transport preparation mode. After the refrigerator detects the transport preparation signal, the compressor stops working, the electromagnetic three-way valve closes, the electromagnetic stop valve opens, and the pressure sensor at the evaporator outlet detects the pressure Pd in ​​the pipeline; The time interval of the detection time period is defined as Td. During the time interval Td, the difference between the two detection pressures Pd is defined as Pe. The critical minimum pressure difference between the compressor and the pipeline between the compressor and the condenser when the lubricating oil flows out of the compressor after the electromagnetic shut-off valve is closed is defined as P3. When it is detected that Pe≤P3, the refrigerator will automatically cut off the power and the electromagnetic stop valve will close.

6. A single-system refrigerator refrigeration system, the system being used to implement the single-system refrigerator refrigeration system control method according to any one of claims 1 to 5, characterized in that: The throttling element of the system includes a capillary tube or an expansion valve or a combination of the two.

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