Control Method of Cascading Refrigeration System for Storage Box

Abstract

The present application provides a control method for a cascade refrigeration system of a storage box, including: step S20, when a door opening signal of the storage box is detected, entering a door opening control mode; step S30, in the door opening control mode, if the cascade refrigeration system is in an operating stage, then step S31 is executed, and the high-temperature compressor and the low-temperature compressor of the cascade refrigeration system are both frequency increased; and / or if the cascade refrigeration system is in a shutdown stage, then step S32 is executed, after the pressure of the cascade refrigeration system reaches equilibrium, the high-temperature compressor and the low-temperature compressor are frequency increased successively; step S40, detecting the box temperature Td of the storage box, and if the box temperature Td reaches a predetermined condition, exiting the door opening control mode.

Description

Technical Field

[0001] This application relates to the technical field of refrigeration equipment, and particularly to a control method for a cascade refrigeration system of a storage box. Background Art

[0002] The refrigeration system used in medical low-temperature storage boxes is mainly a cascade refrigeration system. The cooling method adopted is direct cooling. Multiple layers of freezing shelves are arranged in the compartment, and a plurality of freezing boxes are densely placed on each shelf for storing biological samples. When storing or sampling, the box door and the compartment door are opened, and a large amount of cold energy leaks out.

[0003] In the process of implementing this application, the inventor found that after the compartment door is opened, the temperature of the samples near the outside of the compartment drops rapidly, while the temperature change of the samples near the inside (back) of the compartment is not obvious. As the temperature sensing element for detecting the box temperature is arranged at the back of the compartment, it cannot sense the temperature change of the samples on the door side. After closing the door, if relying on natural convection inside the compartment to cool the samples near the outside of the compartment, this process takes a long time and the cooling is not timely, which may affect the preservation of biological samples. Summary of the Invention

[0004] The purpose of this application is to provide a control method for a cascade refrigeration system of a storage box, aiming to solve the problem in the related art that after the storage box door is closed, relying on natural convection inside the compartment to cool the samples near the outside of the compartment takes a long time, the cooling is not timely, and it may affect the preservation of biological samples.

[0005] This application provides a control method for a cascade refrigeration system of a storage box, including:

[0006] Step S20, when a door opening signal of the storage box is detected, enter the door opening control mode;

[0007] Step S30, in the door opening control mode, if the cascade refrigeration system is in the operating stage, then execute step S31, and the high-temperature compressor and the low-temperature compressor of the cascade refrigeration system are both frequency-increased; and / or if the cascade refrigeration system is in the shutdown stage, then execute step S32, after the pressure of the cascade refrigeration system reaches equilibrium, the high-temperature compressor and the low-temperature compressor are frequency-increased successively;

[0008] Step S40, detect the box temperature Td of the storage box, and if the box temperature Td reaches a predetermined condition, exit the door opening control mode.

[0009] In the control method of some embodiments, the step S31 includes:

[0010] Step S311, the high-temperature compressor and the low-temperature compressor are respectively frequency-increased to the first frequency setting value FH1 and the second frequency setting value FL1; and

[0011] Step S312: After performing step S311, continue to run. If no door closing signal is received during the first time period t1, or a door closing signal is received within the first time period t1, the high-temperature compressor and the low-temperature compressor are frequency-increased to full frequency again.

[0012] In the control method of some embodiments,

[0013] The first frequency setting value FH1 is 30 - 40 Hz; and / or

[0014] The second frequency setting value FL1 is 25 - 35 Hz; and / or

[0015] The first time period t1 is 2 - 4 min.

[0016] In the control method of some embodiments, step S32 includes:

[0017] Step S321: When the pressure of the cascade refrigeration system reaches equilibrium, the high-temperature compressor is frequency-increased to the third frequency setting value FH2;

[0018] Step S322: After performing step S321, continue to run. If no door closing signal is received during the third time period t3, or a door closing signal is received within the third time period t3, the high-temperature compressor is frequency-increased to full frequency again; and

[0019] Step S323: After performing step S322, continue to run for the fifth time period t5, and the low-temperature compressor starts and is frequency-increased to full frequency.

[0020] In the control method of some embodiments,

[0021] The third frequency setting value FH2 is 44 - 55 Hz; and / or

[0022] The third time period t3 is 2 - 4 min; and / or

[0023] The fifth time period t5 is 8 - 14 min.

[0024] In the control method of some embodiments,

[0025] Determine the duration of the fifth time period t5 according to the temperature range of the box temperature Td; or

[0026] Determine the duration of the fifth time period t5 according to the temperature range of the difference between the box temperature Td and the box temperature set value Ts.

[0027] In the control method of some embodiments, in step S30, the predetermined condition includes that the box temperature Td is lower than the box temperature set value Ts by a predetermined temperature value T1 and lasts for the sixth time period t6.

[0028] In the control method of some embodiments, the larger the predetermined temperature value T1 is, the smaller the sixth time period t6 is.

[0029] In the control method of some embodiments, the predetermined temperature value T1 is 3 to 5 °C, and the sixth time period t6 is 10 to 30 min.

[0030] In the control method of some embodiments, the frequency increase rates of the high-temperature compressor and the low-temperature compressor enable the corresponding discharge pressures to be within the allowable operating pressures.

[0031] In the control method of some embodiments, before the step S20, it further includes a step S10. After the storage box is powered on and the temperature is pulled down, the cascade refrigeration system operates stably.

[0032] Based on the control method of the cascade refrigeration system of the storage box provided by the present application, after the box door is opened, the high-temperature compressor and the low-temperature compressor can be controlled respectively according to whether the cascade refrigeration system is in the operating stage or the shutdown stage, and the frequency is reasonably adjusted to obtain a larger refrigerating capacity to quickly cool the samples near the outside of the compartment to the set temperature range.

[0033] Through the following detailed description of the exemplary embodiments of the present application with reference to the drawings, other features and advantages of the present application will become clear. Description of the Drawings

[0034] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0035] Figure 1 It is a schematic diagram of the principle of the cascade refrigeration system of the storage box.

[0036] Figure 2 It is a schematic diagram of the structure of the storage box.

[0037] Figure 3 It is a schematic flowchart of the control method of the cascade refrigeration system of the storage box according to an embodiment of the present disclosure.

[0038] Figures 1 to 2 Among them, each reference numeral represents respectively:

[0039] A1, high-temperature compressor;

[0040] AC, anti-condensation pipe;

[0041] C, condenser;

[0042] D1, first filter;

[0043] J1, the first capillary tube;

[0044] EC, the evaporative condenser;

[0045] GL, the gas-liquid separator;

[0046] A2, the low-temperature compressor;

[0047] O, the oil separator;

[0048] D2, the second filter;

[0049] J2, the second capillary tube;

[0050] E, the evaporator;

[0051] 1, the oil return pipeline;

[0052] 100, the storage box;

[0053] 101, the box door;

[0054] 102, the compartment door;

[0055] 103, the back;

[0056] 104, the first compartment;

[0057] 105, the second compartment;

[0058] 106, the third compartment;

[0059] 107, the fourth compartment;

[0060] 108, the machine compartment;

[0061] 109, the freezing shelf;

[0062] 110, the temperature sensor bulb

[0063] 111, the freezing box. Detailed implementation manners

[0064] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0065] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that for the sake of convenience in description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the specification. In all the examples shown and discussed here, any specific values should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0066] In the description of the present application, it should be understood that the use of terms such as "first" and "second" to limit components is merely for the convenience of distinguishing the corresponding components. Without otherwise stating, the above terms have no special meanings, and thus cannot be construed as limiting the scope of protection of the present application.

[0067] In the description of the present application, it should be understood that the orientation or positional relationships indicated by orientation terms such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom" are usually based on the orientation or positional relationships shown in the drawings, and are merely for the convenience of describing the present application and simplifying the description. Without otherwise stating, these orientation terms do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus cannot be construed as limiting the scope of protection of the present application; the orientation terms "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0068] As Figures 1 to 3 shown, the embodiment of the present application provides a control method for a cascade refrigeration system of a storage box, including:

[0069] Step S20, when a door opening signal of the storage box is detected, enter the door opening control mode;

[0070] Step S30, in the door opening control mode, if the cascade refrigeration system is in the operating stage, then execute Step S31, and the high-temperature compressor A1 and the low-temperature compressor A2 of the cascade refrigeration system are simultaneously frequency increased; and / or if the cascade refrigeration system is in the shutdown stage, then execute Step S32, after the pressure of the cascade refrigeration system reaches equilibrium, the high-temperature compressor A1 and the low-temperature compressor A2 are successively frequency increased;

[0071] Step S40, detect the box temperature Td of the storage box, and if the box temperature Td reaches a predetermined condition, exit the door opening control mode.

[0072] Based on the control method of the cascade refrigeration system of the storage box provided by the embodiments of the present application, after the box door is opened, the high-temperature compressor and the low-temperature compressor can be controlled respectively according to whether the cascade refrigeration system is in the running stage or the shutdown stage, and the frequency is reasonably adjusted to obtain a greater refrigerating capacity to quickly cool the samples near the outer part of the compartment to within the set temperature range.

[0073] In the control method of some embodiments, step S31 includes:

[0074] Step S311, the high-temperature compressor A1 and the low-temperature compressor A2 are respectively frequency-increased to the first frequency setting value FH1 and the second frequency setting value FL1; and

[0075] Step S312, after performing step S311, maintain the operation. If the door closing signal is not received during the first time period t1, or the door closing signal is received within the first time period t1, the high-temperature compressor A1 and the low-temperature compressor A2 are frequency-increased to the full frequency again.

[0076] In the control method of some embodiments,

[0077] The first frequency setting value FH1 is 30-40 Hz; and / or

[0078] The second frequency setting value FL1 is 25-35 Hz; and / or

[0079] The first time period t1 is 2-4 min.

[0080] In the control method of some embodiments, step S32 includes:

[0081] Step S321, when the pressure of the cascade refrigeration system reaches equilibrium, the high-temperature compressor A1 is frequency-increased to the third frequency setting value FH2;

[0082] Step S322, after performing step S321, maintain the operation. If the door closing signal is not received during the third time period t3, or the door closing signal is received within the third time period t3, the high-temperature compressor A1 is frequency-increased to the full frequency again; and

[0083] Step S323, after performing step S322, maintain the operation for the fifth time period t5, and the low-temperature compressor A2 starts and is frequency-increased to the full frequency.

[0084] In the control method of some embodiments,

[0085] The third frequency setting value FH2 is 44-55 Hz; and / or

[0086] The third time period t3 is 2-4 min; and / or

[0087] The fifth time period t5 is 8-14 min.

[0088] In the control method of some embodiments,

[0089] Determine the duration of the fifth time period t5 according to the temperature range in which the chamber temperature Td is located; or

[0090] Determine the duration of the fifth time period t5 according to the temperature range of the difference between the chamber temperature Td and the chamber temperature set value Ts.

[0091] In the control method of some embodiments, in step S30, the predetermined condition includes that the chamber temperature Td is lower than the chamber temperature set value Ts by a predetermined temperature value T1 and maintains the sixth time period t6.

[0092] In the control method of some embodiments, the larger the predetermined temperature value T1, the smaller the sixth time period t6.

[0093] In the control method of some embodiments, the predetermined temperature value T1 is 3 - 5°C, and the sixth time period t6 is 10 - 30 min

[0094] In the control method of some embodiments, the frequency increase rates of the high-temperature compressor A1 and the low-temperature compressor A2 make the corresponding discharge pressures within the allowable operating pressures.

[0095] In the control method of some embodiments, before step S20, it further includes step S10 of saving that after the box is powered on and the temperature is pulled, the cascade refrigeration system operates stably.

[0096] To clarify the purpose, technical solution and advantages of the present application, the following Figures 1 to 3 and specific embodiments are used to further describe the present application in detail.

[0097] The storage box 100 of this embodiment has a cascade refrigeration system. Refer to Figure 1 as shown. The cascade refrigeration system includes a high-temperature stage and a low-temperature stage. On the high-temperature stage refrigerant flow path, a high-temperature compressor A1, an anti-condensation pipe AC, a condenser C, a filter D1, a capillary tube J1 and a gas-liquid separator GL are arranged in sequence. On the low-temperature stage refrigerant flow path, a low-temperature compressor A2, an oil separator O, a filter D2, a capillary tube J2 and an evaporator E are arranged in sequence. An oil return pipeline 1 is arranged between the low-temperature compressor A2 and the oil separator O. The heat exchange between the high-temperature stage and the low-temperature stage is carried out through an evaporative condenser EC.

[0098] Refer to Figure 2As shown in the figure, the storage box 100 is divided into four compartments and a machine compartment 108 from top to bottom. The four compartments are the first compartment 104, the second compartment 105, the third compartment 106, and the fourth compartment 107. The machine compartment 108 mainly houses a high-temperature compressor A1, a low-temperature compressor A2, an inverter, a first filter D1, a second filter D2, a gas-liquid separator GL, a condenser C, a blower, a first capillary tube J1, a second capillary tube J2, an oil separator O, etc. The evaporator E is arranged on the back 103 and the top of the storage box 100 in sequence. The temperature sensing bulb 110 is arranged on the back of the compartment, and in this embodiment, it is arranged on the back of the third compartment 106. The function of the temperature sensing bulb 110 is to detect the temperature inside the box and is used to compare with the set temperature value inside the box. Multiple groups of freezing shelves 109 and freezing boxes 111 are placed in each compartment for storing samples. Figure 2 Only the freezing shelves 109 and freezing boxes 111 inside the third compartment are schematically shown. The storage box 100 has a box door 101 for opening and closing each compartment simultaneously and a plurality of compartment doors 102 arranged on the inner side of the box door 101 and corresponding to each compartment one by one.

[0099] The control method of the cascade refrigeration system of the storage box 100 in this embodiment can effectively reduce the influence of the temperature rise in the compartment caused by the opening and closing of the compartment door of the storage box 100 on the samples inside the compartment. The control flow chart of this control method is as Figure 3 shown.

[0100] After the storage box 100 is powered on and the temperature is pulled down, the cascade refrigeration system operates stably, that is, it enters the start-stop stage. At this time, the box temperature Td < the set box temperature Ts. For example, Td - Ts < 3°C. When the door opening signal is detected, the cascade refrigeration system enters the door opening control mode.

[0101] When the door opening signal is detected during the operation stage, the high-temperature compressor A1 and the low-temperature compressor A2 are frequency-increased to the first frequency set value FH1 and the second frequency set value FL1. FH1 is, for example, 55 Hz. FL1 is, for example, 55 Hz. The frequency-increasing rate is, for example, 1 Hz / 5 s. Since there is heat leakage as soon as the compartment door is opened, the first frequency set value FH1 and the second frequency set value FL1 are given as sub-high-frequency values, and the high-temperature compressor A1 and the low-temperature compressor A2 are frequency-increased to increase the refrigeration capacity.

[0102] The high-temperature compressor A1 maintains the first frequency set value FH1, and the low-temperature compressor A2 maintains the second frequency set value FH2 for operation. After the first time period t1, if the door closing signal is not received, the high-temperature compressor A1 and the low-temperature compressor A2 increase their frequencies to the full frequency at a certain frequency increase rate, or if the door closing signal is received within the first time period t1, the high-temperature compressor A1 and the low-temperature compressor A2 also quickly increase their frequencies to the full frequency. Based on avoiding serious cold leakage due to the door not being closed for a long time and a sharp increase in the temperature inside the storage box 100, a time constraint is given. If the door is not closed after maintaining operation for the first time period t1, the compressors need to be increased in frequency to the full frequency. For example, t1 is 3 minutes.

[0103] In this embodiment, to improve the refrigeration rate, when increasing the frequency, within the allowable working pressure of the compressor, the frequency can be quickly increased. However, the frequency increase rate of all steps should ensure that the exhaust pressure of the compressor does not become too high and exceed the working pressure of the compressor.

[0104] When the door opening signal is detected during the shutdown stage and the pressure of the cascade refrigeration system reaches equilibrium, the high-temperature compressor A1 starts, and the starting frequency is, for example, 43 Hz, and then it increases in frequency to the third frequency set value FH2. In order to make up for the cold leakage when the door is opened and obtain a larger refrigeration capacity, a sub-high frequency value is given just when the door is opened.

[0105] Among them, the cascade refrigeration system has a long pipeline. When the compressor just shuts down, the pressure inside the cascade refrigeration system cannot quickly balance and stabilize. The pressure of the compressor exhaust pipe is the highest. Along the refrigerant flow direction, the pressure gradually decreases, and the pressure of the compressor intake pipe is the lowest. Therefore, when the exhaust pressure of the compressor is approximately equal to the suction pressure, it can be determined that the pressure of the cascade refrigeration system reaches equilibrium. The purpose of pressure equilibrium is to avoid the problem that the exhaust pressure of the compressor may be too high and cause the compressor to trip when starting.

[0106] After the third time period t3, if the door closing signal is not received, or if the door closing signal is received within the third time period t3, the high-temperature compressor A1 starts. For example, the starting frequency is 43 Hz, and then it increases in frequency to the full frequency at a certain frequency increase rate. Based on avoiding serious cold leakage due to the door not being closed for a long time and a sharp increase in the temperature inside the storage box 100, a time constraint is given. If the door is not closed after the third time period t3, the compressors need to be increased in frequency to the full frequency, mainly to ensure that the temperature inside the storage box 100 does not increase too much and affect the normal storage of the samples. For example, t3 is 3 minutes.

[0107] After the high-temperature compressor A1 operates at the third frequency set value FH2 for the fifth time period t5, the low-temperature compressor A2 starts, and the starting frequency is, for example, 43 Hz, and it increases in frequency to the full frequency.

[0108] Among them, when the cabinet temperature Td is relatively low, the amount of cooling required for the cabinet temperature Td to drop to the set value Ts is small, and the fifth time period t5 during which the high-temperature compressor A1 operates is short. Therefore, the fifth time period t5 during which the high-temperature compressor A1 operates varies in different cabinet temperature Td stages. In some embodiments, the duration of the fifth time period t5 can be determined according to the temperature range in which the cabinet temperature Td is located. For example, the following table shows a feasible determination method:

[0109]

[0110] In some other embodiments, the duration of the fifth time period t5 can also be determined according to the temperature range of the difference between the cabinet temperature Td and the cabinet temperature set value Ts.

[0111] When the cabinet temperature Td drops to be lower than the cabinet temperature set value Ts by a predetermined temperature value T1 and is maintained for a sixth time period t6, that is, Td ≤ Ts - T1, the door opening control mode is exited. T1 and t6 have a corresponding relationship. The larger the value of T1, the shorter the sixth time period t6. For example, t6 = 30 min and T1 = 3°C; or t6 = 10 min and T1 = 5°C.

[0112] According to the above description, it can be known that for the control method of the cascade refrigeration system of the storage box in the embodiments of the present application, aiming at the problem that the opening and closing of the compartment door may cause the compartment temperature to rise, the operating frequencies of the high-temperature compressor A1 and the low-temperature compressor A2 are reasonably adjusted, the compressor speed is controlled, the cooling capacity is obtained, the compartment temperature is quickly reduced to a reasonable set temperature range, and the influence of the temperature rise caused by the opening and closing of the door on the sample is reduced.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them; although the present application has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present application can still be modified or some technical features can be equivalently replaced, and all of them should be covered by the scope of the technical solutions claimed in the present application.

Claims

1. A control method for a cascade refrigeration system of a storage box, characterized in that, Including: Step S20: When a door opening signal of the storage box is detected, enter the door opening control mode. Step S30: In the door opening control mode, if the cascade refrigeration system is in the operating stage, execute Step S31, and the high-temperature compressor (A1) and the low-temperature compressor (A2) of the cascade refrigeration system are both frequency-increased simultaneously; and / or if the cascade refrigeration system is in the shutdown stage, execute Step S32. After the pressure of the cascade refrigeration system reaches equilibrium, the high-temperature compressor (A1) and the low-temperature compressor (A2) are frequency-increased successively; and Step S40: Detect the box temperature Td of the storage box. If the box temperature Td reaches a predetermined condition, exit the door opening control mode. Among them, Step S32 includes: Step S321: When the pressure of the cascade refrigeration system reaches equilibrium, the high-temperature compressor (A1) is frequency-increased to the third frequency setting value FH2. Step S322: After executing Step S321, maintain the operation. If the door closing signal is not received during the third time period t3, or the door closing signal is received within the third time period t3, the high-temperature compressor (A1) is frequency-increased to full frequency again; and Step S323: After executing Step S322, maintain the operation for the fifth time period t5, and the low-temperature compressor (A2) is started and frequency-increased to full frequency.

2. The control method according to claim 1, wherein Step S31 includes: Step S311: The high-temperature compressor (A1) and the low-temperature compressor (A2) are respectively frequency-increased to the first frequency setting value FH1 and the second frequency setting value FL1. Step S312: After executing Step S311, maintain the operation. If the door closing signal is not received during the first time period t1, or the door closing signal is received within the first time period t1, the high-temperature compressor (A1) and the low-temperature compressor (A2) are frequency-increased to full frequency again.

3. The control method according to claim 2, wherein The first frequency setting value FH1 is 30 - 40 Hz; and / or The second frequency setting value FL1 is 25 - 35 Hz; and / or The first time period t1 is 2 - 4 min.

4. The control method according to claim 1, wherein The third frequency setting value FH2 is 44 - 55 Hz; and / or The third time period t3 is 2 - 4 min; and / or The fifth time period t5 is 8 - 14 min.

5. The control method according to claim 1, wherein Determine the duration of the fifth time period t5 according to the temperature range where the box temperature Td is located; or Determine the duration of the fifth time period t5 according to the temperature range where the difference between the box temperature Td and the box temperature setting value Ts is located.

6. The control method according to claim 1, wherein In Step S30, the predetermined condition includes that the box temperature Td is lower than the box temperature setting value Ts by a predetermined temperature value T1 and is maintained for the sixth time period t6.

7. The control method according to claim 6, wherein The larger the predetermined temperature value T1 is, the smaller the sixth time period t6 is.

8. The control method according to claim 6, characterized in that The predetermined temperature value T1 is 3 - 5 °C, and the sixth time period t6 is 10 - 30 min.

9. The control method according to any one of claims 1 to 8, characterized in that, The frequency increase rates of the high-temperature compressor (A1) and the low-temperature compressor (A2) ensure that the corresponding discharge pressures are within the allowable operating pressures.

10. The control method according to any one of claims 1 to 8, characterized in that, Before the step S20, there is also a step S10. After the storage box is powered on and the temperature is pulled down, the cascade refrigeration system operates stably.

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