Drawer-type freezing unit, refrigerator and control method thereof

Abstract

The application provides a drawer type freezing unit, a refrigerator and a control method thereof, and belongs to an energy-saving refrigerator and freezer. The drawer type freezing unit comprises a frame, a drawer, an air pump and a pressure sensor. The air pump is arranged outside the frame, the pressure sensor is arranged in the frame, the drawer is inserted into the frame, and the frame and the drawer form a closed freezing chamber. The air pipe of the air pump is connected to the freezing chamber, and the pressure sensor is used for detecting the pressure in the freezing chamber in real time. According to the application, the air volume of the air pump is guided by the pressure sensor, so that the freezing chamber is in a suitable micro-negative pressure environment. The suitable micro-negative pressure environment actively intervenes the ice crystals on the food stored in the freezing chamber from the perspective of thermodynamics, significantly slows down the recrystallization and migration speed of the ice crystals, and thus protects the tissue structure of the food and improves the quality of the frozen food in the storage process.

Description

Technical Field

[0001] This invention relates to the field of refrigerator technology, specifically to a drawer-type freezing unit, a refrigerator and its control method, belonging to the category of energy-saving refrigerators and freezers. Background Technology

[0002] The primary cause of food quality deterioration during frozen storage lies in the recrystallization of ice crystals. Even if initial small ice crystals are formed through quick-freezing, over a storage period of several weeks to months, unavoidable temperature fluctuations within the freezer (such as defrosting cycles, door openings, and compressor start-ups / stops) cause the ice crystal system to spontaneously tend towards an equilibrium state that lowers its total surface energy. This means that water molecules on the surface of small ice crystals gradually detach from the crystal lattice, migrate to the surface of larger ice crystals via gas phase or surface diffusion, and re-condense, causing the larger ice crystals to grow larger while the smaller ones gradually disappear. The direct consequence of this phenomenon is that initially small ice crystals gradually grow into sharp, large ice crystals during storage, continuously causing mechanical damage to the cellular structure of the food. Upon thawing, the damaged cells cannot retain moisture, resulting in significant juice loss, leading to a decline in taste and nutrient loss. Summary of the Invention

[0003] Therefore, the present invention provides a drawer-type freezing unit, a refrigerator and its control method, which belongs to energy-saving refrigerators and freezers, and can solve the technical problem that existing freezing and preservation technologies cannot effectively inhibit the recrystallization of ice crystals during long-term storage, thus leading to the deterioration of food quality.

[0004] To address the aforementioned problems, the present invention provides a drawer-type freezing unit, comprising a frame, a drawer, an air pump, and a pressure sensor. The air pump is disposed outside the frame, the pressure sensor is installed inside the frame, the drawer is inserted into the frame, and the two together form a closed freezing chamber. The air pipe of the air pump leads to the freezing chamber, and the pressure sensor is used to detect the pressure inside the freezing chamber in real time.

[0005] In some embodiments, the drawer-type refrigeration unit further includes a controlled atmosphere membrane assembly through which the air pipe of the air pump leads to the refrigeration compartment, the controlled atmosphere membrane assembly being used to selectively allow oxygen to pass through.

[0006] In some embodiments, the modified atmosphere membrane assembly includes a housing and a plurality of modified atmosphere membranes, the housing having a receiving cavity and an opening, each of the modified atmosphere membranes being stacked within the receiving cavity, the receiving cavity communicating with the refrigeration chamber through the opening, and an air tube of the air pump being inserted into the receiving cavity and into the stacked modified atmosphere membranes.

[0007] In some embodiments, the controlled atmosphere membrane assembly is mounted within the frame, and the controlled atmosphere membrane assembly further includes a fan, which is fixed to the housing by a bracket, and the opening is located on the air outlet side of the fan.

[0008] In some embodiments, a temperature sensor is installed inside the frame to detect the temperature inside the freezer compartment in real time.

[0009] In some embodiments, a vent valve is installed on the frame.

[0010] The present invention also provides a refrigerator, including the aforementioned drawer-type freezing unit.

[0011] The present invention also provides a refrigerator control method for controlling the operation of the aforementioned refrigerator. The control method includes: starting the air pump to depressurize the freezer compartment, and turning off the air pump after the pressure in the freezer compartment reaches a first set pressure.

[0012] In some implementations, the refrigerator is controlled to operate in a subcooling freezing mode before the air pump is activated to depressurize the freezer compartment.

[0013] In some embodiments, the supercooling freezing mode includes controlling the refrigerator to operate at a stepped-down set temperature for a set duration at each set temperature.

[0014] In some embodiments, controlling the refrigerator to operate at a stepped-down set temperature, and operating at each set temperature for a set duration, includes the following steps: Step 1: Control the freezer compartment to operate at the first set temperature for the first set duration; Step 2: Control the freezer compartment to operate at the second set temperature for the second set duration; Step 3: Control the freezer compartment to operate at the third set temperature for the third set duration; Step 4: Control the freezer compartment to operate at the fourth set temperature for the fourth set duration; Step 5: Control the freezer compartment to operate at the fifth set temperature for the fifth set duration; Wherein, the first set temperature > the second set temperature > the third set temperature > the fourth set temperature > the fifth set temperature; the first set duration ≥ the second set duration, the first set duration ≥ the third set duration, the first set duration ≥ the fourth set duration, and the first set duration ≥ the fifth set duration.

[0015] In some implementations, after the supercooling freezing mode ends, the refrigerator is controlled to operate at a fourth set temperature.

[0016] In some implementations, when defrosting of the refrigerator is detected, the air pump is restarted to depressurize the freezer compartment again, and the air pump is turned off again after the pressure in the freezer compartment reaches a second set pressure; wherein the second set pressure is less than the first set pressure.

[0017] The present invention provides a drawer-type freezing unit, a refrigerator, and a control method thereof, which have the following beneficial effects: Since the air pump's air pipe leads to the freezer compartment formed by the combination of the drawer and the frame, and the pressure sensor is used to detect the pressure inside the freezer compartment in real time, the pressure sensor guides the air pump's pumping volume, allowing the freezer compartment to maintain a suitable micro-negative pressure environment. This suitable micro-negative pressure environment enables active intervention on the ice crystals on the food stored in the freezer compartment from a thermodynamic perspective, significantly slowing down the recrystallization and migration rate of ice crystals, thereby protecting the food's structure, improving the quality of frozen food during storage, and providing an energy-saving refrigerator / freezer. Attached Figure Description

[0018] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0019] Figure 1 This is a schematic diagram showing the frame and drawer of the drawer-type freezing unit in an embodiment of the present invention in a separated state; Figure 2 This is a schematic diagram of the frame and drawer of the drawer-type freezing unit in an embodiment of the present invention in a combined state; Figure 3 This is a schematic diagram of the controlled atmosphere membrane assembly of the drawer-type freezing unit according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a refrigerator according to an embodiment of the present invention; Figure 5 This is a first control flowchart of a refrigerator according to an embodiment of the present invention; Figure 6 This is a second control flowchart of a refrigerator according to an embodiment of the present invention; Figure 7 This is a control flowchart of a refrigerator operating in supercooled freezing mode according to an embodiment of the present invention; Figure 8 This is a graph showing the relationship between temperature and time when the refrigerator of this embodiment is running in the supercooling freezing mode; Figure 9 A graph showing the relationship between pressure and ice melting point; Figure 10 This is a graph showing the relationship between pressure and ice melting point within a slightly negative pressure range.

[0020] The reference numerals in the attached figures are as follows: 1. Drawer-type refrigeration unit; 2. Frame; 3. Drawer; 4. Air pump; 5. Pressure sensor; 6. Controlled atmosphere membrane assembly; 61. Housing; 62. Controlled atmosphere membrane; 63. Fan; 7. Temperature sensor; 8. Vent valve. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0023] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0024] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0025] See also Figures 1 to 10 As shown, according to an embodiment of the present invention, a drawer-type freezing unit 1 is provided, including a frame 2, a drawer 3, an air pump 4 and a pressure sensor 5. The air pump 4 is disposed outside the frame 2, the pressure sensor 5 is installed inside the frame 2, the drawer 3 is inserted into the frame 2 and the two enclose each other to form a closed freezing chamber, the air pipe of the air pump 4 leads to the freezing chamber, and the pressure sensor 5 is used to detect the pressure inside the freezing chamber in real time.

[0026] In this technical solution, since the air pipe of the air pump 4 leads to the freezer compartment formed by the combination of drawer 3 and frame 2, and the pressure sensor 5 is used to detect the pressure inside the freezer compartment in real time, the pressure sensor 5 guides the air pump 4 to maintain a suitable micro-negative pressure environment in the freezer compartment. This suitable micro-negative pressure environment enables active intervention on the ice crystals on the food stored in the freezer compartment from a thermodynamic perspective, significantly slowing down the recrystallization and migration rate of ice crystals, thereby protecting the food's structure, improving the quality of frozen food during storage, and enhancing the stability and controllability of freezing and preservation, thus providing an energy-saving refrigerator / freezer. The frame 2 is equipped with a high-performance sealing strip, which ensures that the freezer compartment is isolated from the outside atmosphere when the drawer 3 is inserted into the frame 2. Preferably, the air pump 4 is a micro-air pump.

[0027] See Figure 1 As shown, the drawer-type refrigeration unit 1 also includes a controlled atmosphere membrane assembly 6. The air pipe of the air pump 4 is connected to the refrigeration compartment through the controlled atmosphere membrane assembly 6. The controlled atmosphere membrane assembly 6 is used to selectively allow oxygen to pass through, that is, only oxygen can pass through the controlled atmosphere membrane assembly 6.

[0028] In this embodiment, by adding a modified atmosphere membrane assembly 6, when the air pump 4 draws air, only a suitable amount of oxygen in the freezer compartment can be removed. This not only ensures that the freezer compartment is in a suitable micro-negative pressure environment, but also reduces the oxygen content in the freezer compartment, thus preventing the food from oxidizing during storage.

[0029] See also Figure 1 and Figure 3As shown, the modified atmosphere membrane assembly 6 includes a housing 61 and a plurality of modified atmosphere membranes 62. The housing 61 has a receiving cavity and an opening. Each modified atmosphere membrane 62 is stacked in the receiving cavity. The receiving cavity is connected to the refrigeration chamber through the opening. The air pipe of the air pump 4 is led to the receiving cavity and inserted into the stacked modified atmosphere membranes 62. The stacked modified atmosphere membranes 62 can form a better filtration effect, ensuring that only oxygen can pass through the modified atmosphere membranes 62. Preferably, the stacked modified atmosphere membranes 62 fill the receiving cavity of the housing 61.

[0030] See also Figure 1 and Figure 3 As shown, the modified atmosphere membrane assembly 6 is installed inside the frame 2. The modified atmosphere membrane assembly 6 also includes a fan 63, which is fixed to the housing 61 by a bracket, with its opening located on the air outlet side. As oxygen is continuously drawn from the freezer compartment, nitrogen continuously accumulates on the surface of each modified atmosphere membrane 62. Excessive nitrogen accumulation on the surface of each modified atmosphere membrane 62 hinders oxygen permeation, affecting the efficiency of oxygen reduction. By adding the fan 63 aligned with the opening in the housing 61, the nitrogen on the surface of the modified atmosphere membrane 62 can be blown away. It is understood that because the modified atmosphere membrane assembly 6 is installed inside the frame 2, the fan 63 is located within the enclosed freezer compartment; therefore, the airflow driven by the fan 63 within the enclosed freezer compartment will not affect the air pressure in the freezer compartment. It should be noted that after the modified atmosphere membrane assembly 6 is installed inside the frame 2, the wall of the drawer 3 is constructed with a notch to allow the modified atmosphere membrane assembly 6 to pass through, while the air pipe of the air pump 4 passes through the frame 2 and the housing 61 and is inserted into the stacked modified atmosphere membrane 62.

[0031] See Figure 1 As shown, a temperature sensor 7 is installed inside the frame 2, which is used to monitor the temperature inside the freezer compartment in real time. A vent valve 8 is installed on the frame 2, which is designed to quickly restore the pressure inside the freezer compartment to normal atmospheric pressure when an abnormal pressure occurs.

[0032] The present invention also provides a refrigerator, including the aforementioned drawer-type freezing unit.

[0033] This invention also provides a refrigerator control method for controlling the operation of the aforementioned refrigerator. The control method includes: starting an air pump 4 to depressurize the freezer compartment, and turning off the air pump 4 after the pressure inside the freezer compartment reaches a first set pressure. The first set pressure is P, where -0.1 bar ≤ P ≤ -0.7 bar. It can be understood that under this slightly negative pressure environment, the melting point of ice crystals increases slightly, and the ice crystals become more thermodynamically stable. This changes the thermodynamic activity of molecules on the ice crystal surface, making it more difficult for water molecules to detach from the crystal lattice and migrate, thereby significantly slowing down the rate of material migration between ice crystals and inhibiting the recrystallization process.

[0034] See Figure 6As shown, if the user puts in meat, the air pump 4 is turned on to make the pressure in the freezer compartment P1, -0.1 bar ≤ P1 ≤ -0.3 bar, and the pressure is maintained by feedback from the pressure sensor 5; if the user puts in seafood, the air pump 4 is turned on to make the pressure in the freezer compartment P2, -0.4 bar ≤ P2 ≤ -0.6 bar, and the pressure is maintained by feedback from the pressure sensor 5; if the user puts in mixed ingredients, the air pump 4 is turned on to make the pressure in the freezer compartment P3, -0.5 bar ≤ P3 ≤ -0.7 bar, and the pressure is maintained by feedback from the pressure sensor 5.

[0035] According to phase diagram studies of water, the melting point of ice exhibits a unique negative slope relationship with pressure. For example... Figure 9 and Figure 10 As shown, in the positive pressure region (>0 bar), increased pressure leads to a decrease in melting point; while in the negative pressure region (<0 bar), decreased pressure leads to an increase in melting point. This application utilizes the characteristic of increased melting point in the negative pressure region to maintain a slight negative pressure (e.g., -0.1 to -0.8 bar) in the freezing compartment during the freezing storage stage. Although the increase in melting point within this small negative pressure range is only on the order of 0.004°C, it is sufficient to alter the thermodynamic activity and migration kinetics of molecules on the ice crystal surface, thereby inhibiting ice crystal recrystallization during long-term storage. Applying a slight negative pressure (e.g., -0.1 bar to -0.8 bar) to the environment of the food during the freezing storage stage inhibits ice crystal recrystallization through the following mechanism: I. Thermodynamic Stabilization Mechanism Under negative pressure, the apparent melting point of ice crystals increases slightly, indicating that the ice crystals are thermodynamically more stable. Although the increase in melting point is only on the order of 0.004 °C within the small negative pressure range (-0.1 to -0.8 bar) of interest in this application, this is sufficient to alter the thermodynamic activity of molecules on the ice crystal surface. Water molecules on the ice crystal surface are in a high-energy state and are the main source of mass migration during recrystallization. The negative pressure makes it more difficult for these surface molecules to overcome the energy barrier and escape from the crystal lattice, thus significantly slowing down the rate of mass migration between ice crystals.

[0036] II. Surface Energy Regulation Mechanism The driving force for recrystallization comes from the surface energy difference between ice crystals of different sizes. The negative pressure environment changes the distribution of unpaired hydrogen bonds on the surface of ice crystals, reduces the surface energy gradient between small and large ice crystals, and eliminates the thermodynamic driving force of "large ice crystals engulfing small ice crystals".

[0037] III. Migration Dynamics Inhibition Mechanism According to the kinetic theory of molecules, water molecules need to overcome a certain activation energy to escape from the crystal lattice on the surface of ice crystals. The negative pressure effect is equivalent to raising this activation energy barrier, which reduces the probability of water molecules escaping from the crystal lattice per unit time, thus inhibiting the growth of ice crystals from a kinetic perspective.

[0038] See Figure 5 As shown, before activating air pump 4 to depressurize the freezer compartment, the refrigerator operates in subcooling freezing mode. Subcooling freezing ensures that ice crystals are controlled to be small and evenly distributed inside and outside the food cells during freezing, reducing cell damage caused by ice crystals. After freezing, maintaining a slightly negative pressure environment in the freezer compartment further enhances the stability of ice crystals within the food, better inhibiting recrystallization and further reducing cell damage from ice crystal growth during storage. This achieves ice crystal control throughout the entire process from freezing to storage, resulting in better food preservation quality. It should be noted that... Figure 5 The micro air pump mentioned is the air pump 4 of this application, and the compartment is the refrigeration compartment.

[0039] As a specific implementation method, the subcooling freezing mode includes controlling the refrigerator to operate at a stepped decrease in set temperature, with each set temperature operating for a set duration. This stepped cooling provides sufficient cooling time for the food, thus avoiding inconsistent overall temperature distribution and preventing temperature differences between the surface and interior of the food from preventing it from undergoing subcooling.

[0040] More specifically, controlling the refrigerator to operate at a stepped-down set temperature, with each set temperature operating for a set duration, includes the following steps: Step 1: Control the freezer compartment to operate at the first set temperature for the first set duration; Step 2: Control the freezer compartment to operate at the second set temperature for the second set duration; Step 3: Control the freezer compartment to operate at the third set temperature for the third set duration; Step 4: Control the freezer compartment to operate at the fourth set temperature for the fourth set duration; Step 5: Control the freezer compartment to operate at the fifth set temperature for the fifth set duration; Among them, the first set temperature > the second set temperature > the third set temperature > the fourth set temperature > the fifth set temperature, 0℃ ≤ the first set temperature ≤ 5℃, -8℃ ≤ the second set temperature ≤ -1℃, -8℃ ≤ the third set temperature ≤ -1℃, -8℃ ≤ the fourth set temperature ≤ -1℃, -8℃ ≤ the fifth set temperature ≤ -18℃; the first set duration ≥ the second set duration, the first set duration ≥ the third set duration, the first set duration ≥ the fourth set duration, the first set duration ≥ the fifth set duration, the first set duration ≥ 4h, 2h ≤ the second set duration ≤ 4h, 2h ≤ the third set duration ≤ 4h, 2h ≤ the fourth set duration ≤ 4h, 2h ≤ the fifth set duration ≤ 4h.

[0041] In this embodiment, step one is the pre-cooling stage, ensuring that the overall temperature of the food in the freezer compartment reaches the first set temperature. Steps two, three, and four are the supercooling maintenance stages, where gradient cooling is performed to give the food sufficient cooling time, thus avoiding inconsistent overall temperature and allowing the food to enter supercooling without freezing below the freezing point. Step five is the supercooling release stage, where rapid cooling creates a temperature field disturbance, releasing the food from the supercooled state and causing it to freeze as a whole, thereby reducing the damage of ice crystals to the food cells. This stage can also be achieved by disturbing the food with a magnetic field or electric field. If an electric field is applied to release the supercooling, a high-voltage electrostatic device is required, including an electrostatic transformer and an electrostatic discharge device. The electrostatic discharge device is located in the freezer compartment, and the electrostatic transformer is connected to the electrostatic discharge device and the main control board. The main control board controls the electrostatic transformer to connect to an external voltage and output voltage to the electrostatic discharge device, causing the electrostatic discharge device to generate a high-voltage electrostatic field in the freezer compartment of the refrigerator. When the supercooling is de-cooled, the main control board activates the high-voltage electrostatic device, instantly filling the freezer compartment with a strong electrostatic field. The supercooled food and its water molecules collide under the influence of this field, rapidly de-cooling the food. Alternatively, if a magnetic field is used to de-cool, a magnetic field generator is required. An electromagnetic plate is installed on the top or side of the freezer compartment, and the generation and shutdown of the electromagnetic field are controlled by voltage. When supercooling needs to be de-cooled, the electromagnetic field generator is activated, causing the supercooled food and its water molecules to move and collide under the influence of the electromagnetic field, rapidly de-cooling the food.

[0042] It should be noted that, Figure 7In this context, T1 represents the first set temperature, and t1 represents the first set duration; T2 represents the second set temperature, and t2 represents the second set duration; T3 represents the third set temperature, and t3 represents the third set duration; T4 represents the fourth set temperature, and t4 represents the fourth set duration; and T5 represents the fifth set temperature, and t5 represents the fifth set duration. During refrigerator operation, the real-time temperature inside the compartment is detected by temperature sensor 7. When the temperature reaches the first preset start-up temperature value TON1, the compressor is controlled to start; when the temperature reaches the first preset stop-off temperature value TOFF1, the compressor is controlled to stop. TON1 = T1 + TB1 / 2, TOFF1 = TON1 - TB2 / 2; TB1 and TB2 are known parameters. TB1 refers to the temperature rise above the start-up point of the compartment during compressor start-up; TB2 refers to the temperature difference between the start-up and stop-off of the freezer compartment.

[0043] As a specific implementation method, after the supercooling freezing mode ends, the refrigerator is controlled to operate at the fourth set temperature. It should be noted that the fifth set temperature is lower than the fourth set temperature, which can freeze food quickly. However, the food cannot be kept at a consistently low temperature, otherwise it will freeze solid. Therefore, after the freezer compartment operates at the fifth set temperature for the fifth set time, the refrigerator needs to be controlled to operate at the fourth set temperature. This ensures that the food is at a temperature that can be frozen, but the freezing temperature is not too low. Figure 8 The diagram shows the temperature and time relationship between the refrigerator from the start to the end of the subcooling freezing mode and when it runs at the fourth set temperature.

[0044] More specifically, when defrosting of the refrigerator is detected, the air pump 4 is restarted to depressurize the freezer compartment again. After the pressure in the freezer compartment reaches the second set pressure, the air pump 4 is turned off again. The second set pressure is less than the first set pressure, and the second set pressure is P4, -0.6 bar ≤ P4 ≤ -0.8 bar.

[0045] In this technical solution, the temperature inside the freezer compartment rises during defrosting. Adjusting the pressure inside the freezer compartment to a lower second set pressure will raise the melting point, which can reduce the melting and recrystallization of ice crystals caused by the temperature rise.

[0046] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above are merely preferred embodiments of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A drawer-type freezing unit (1), characterized in that, The device includes a frame (2), a drawer (3), an air pump (4), and a pressure sensor (5). The air pump (4) is located outside the frame (2), and the pressure sensor (5) is installed inside the frame (2). The drawer (3) is inserted into the frame (2), and the two together form a closed freezer compartment. The air pipe of the air pump (4) leads to the freezer compartment, and the pressure sensor (5) is used to detect the pressure inside the freezer compartment in real time.

2. The drawer-type freezing unit (1) according to claim 1, characterized in that, It also includes a controlled atmosphere membrane assembly (6), through which the air pipe of the air pump (4) leads to the freezer compartment, the controlled atmosphere membrane assembly (6) being used to selectively allow oxygen to pass through.

3. The drawer-type freezing unit (1) according to claim 2, characterized in that, The modified atmosphere membrane assembly (6) includes a housing (61) and a plurality of modified atmosphere membranes (62). The housing (61) has a receiving cavity and an opening. Each of the modified atmosphere membranes (62) is stacked in the receiving cavity. The receiving cavity is connected to the freezing chamber through the opening. The air pipe of the air pump (4) is connected to the receiving cavity and inserted into the stacked modified atmosphere membranes (62).

4. The drawer-type freezing unit (1) according to claim 3, characterized in that, The modified atmosphere membrane assembly (6) is installed inside the frame (2). The modified atmosphere membrane assembly (6) also includes a fan (63). The fan (63) is fixed to the housing (61) by a bracket. The opening is located on the air outlet side of the fan (63).

5. The drawer-type freezing unit (1) according to claim 1, characterized in that, A temperature sensor (7) is installed inside the frame (2), and the temperature sensor (7) is used to detect the temperature inside the freezer room in real time.

6. The drawer-type freezing unit (1) according to claim 1, characterized in that, A vent valve (8) is installed on the frame (2).

7. A refrigerator, characterized in that it includes a drawer-type freezing unit (1) as described in any one of claims 1 to 6.

8. A method for controlling a refrigerator, characterized in that it is used to control the operation of the refrigerator according to claim 7, the control method comprising: The air pump (4) is started to depressurize the freezer compartment. The air pump (4) is turned off after the pressure in the freezer compartment reaches the first set pressure.

9. The control method according to claim 8, characterized in that, Before starting the air pump (4) to depressurize the freezer compartment, control the refrigerator to operate in subcooling freezing mode.

10. The control method according to claim 9, characterized in that, The subcooling freezing mode includes controlling the refrigerator to operate at a stepped decrease in the set temperature, and operating for a set duration at each set temperature.

11. The control method according to claim 10, characterized in that, Controlling the refrigerator to operate at a stepped-down set temperature, with each set temperature operating for a set duration, includes the following steps: Step 1: Control the freezer compartment to operate at the first set temperature for the first set duration; Step 2: Control the freezer compartment to operate at the second set temperature for the second set duration; Step 3: Control the freezer compartment to operate at the third set temperature for the third set duration; Step 4: Control the freezer compartment to operate at the fourth set temperature for the fourth set duration; Step 5: Control the freezer compartment to operate at the fifth set temperature for the fifth set duration; Wherein, the first set temperature > the second set temperature > the third set temperature > the fourth set temperature > the fifth set temperature; the first set duration ≥ the second set duration, the first set duration ≥ the third set duration, the first set duration ≥ the fourth set duration, and the first set duration ≥ the fifth set duration.

12. The control method according to claim 11, characterized in that, After the supercooling freezing mode ends, the refrigerator is controlled to operate at the fourth set temperature.

13. The control method according to claim 8, characterized in that, When the defrosting of the refrigerator is detected, the air pump (4) is restarted to depressurize the freezer compartment again. After the pressure in the freezer compartment reaches the second set pressure, the air pump (4) is turned off again; wherein the second set pressure is less than the first set pressure.

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