Air-cooling defrosting device of frostless refrigerator and control method

Abstract

The invention discloses an air-cooling defrosting device of a frostless refrigerator and a control method. When the compressor works, a liquid refrigerant enters the evaporator coil through the expansion valve to be gasified. The shaftless fan and the electromagnetic pawl at the front end of the stator are powered on, the rotor can only blow air in the forward direction, the shaftless fan pumps out air in the quick-freezing chamber and feeds the air into the foamed plastic heat preservation special-shaped square pipe, steam in the air releases evaporation heat, and the evaporation heat is condensed on the evaporator coil pipe to form frost. Cold air pushes away the heat insulation cloth strips on the horizontal gaps and enters the quick-freezing chamber. After the compressor stops working, the shaftless fan is powered on again, the electromagnetic pawl at the rear end of the stator is powered on, the rotor can only blow air after rotating reversely, 4-DEG C air and water vapor in the fresh-keeping chamber enter the foamed plastic heat preservation special-shaped square pipe, heat and cold air are released on the evaporator coil pipe and return to the fresh-keeping chamber, and frost on the evaporator coil pipe is melted into water. 0 DEG C water is pushed by flowing air to flow into the vertical foam plastic heat preservation wide square pipe, penetrates through the sponge and flows into the water collecting tank from the water drainage pipe.

Description

TECHNICAL FIELD

[0001] The present invention relates to an air-blast defrosting device and control method for a frost-free refrigerator. BACKGROUND

[0002] In 1995, Samsung Electronics Co. Ltd. of Korea applied for a patent for an invention entitled "Defrosting device for refrigerator and method for controlling the same". The structure of the invention is as follows: a fan is installed in the left side of the space between the inner and outer shells of the refrigerator; there is a horizontal slit in the left side wall of the refrigerating chamber; there are three horizontal slits in the right side wall of the refrigerating chamber; there are three horizontal slits in the left side wall of the three quick-freezing chamber evaporator coils; and there are three horizontal slits in the right side wall of the three quick-freezing chamber evaporator coils. The fan in the left side of the space between the inner and outer shells of the refrigerator draws the 4℃ hot air in the refrigerating chamber out of the horizontal slit in the left side wall of the refrigerating chamber, blows the 4℃ hot air into the three quick-freezing chambers through the three horizontal slits in the left side wall of the three quick-freezing chamber evaporator coils, melts the frost on the three quick-freezing chamber evaporator coils, and then the cold air in the three quick-freezing chambers, which is below 0℃, enters the right side wall space through the three horizontal slits in the right side wall of the three quick-freezing chamber evaporator coils, and then enters the refrigerating chamber through the horizontal slit in the right side wall of the refrigerating chamber. The existing frosty refrigerator is defrosted manually once a month: the food in the quick-freezing chambers is moved to the refrigerating chamber, the power plug of the refrigerator is pulled out, the refrigerator is powered off for 12 hours, the frost on the three quick-freezing chamber evaporator coils and the cooling fins melts and falls into the three quick-freezing chamber boxes, and the water in the three quick-freezing chamber boxes exceeds one kg. That is, the frost on the three quick-freezing chamber evaporator coils and the cooling fins is 20g per day, and in summer, the compressor is not worried about running once an hour, and each time the frost is close to 2g. The heat of fusion of frost is 80 cal / g, and the heat required to melt 2g of frost is 160 cal. The volume of the refrigerating chamber is less than 1m³, the specific gravity of air is 1.29g / m³, and the air in the refrigerating chamber is less than 1g. The specific heat of air is 0.7 cal / g, and the heat released when the 4℃ air in the refrigerating chamber is reduced to 0℃ is less than 3 cal. After the compressor of the refrigerator runs once, the fan in the left side of the space between the inner and outer shells of the refrigerator runs ten times, and the 44℃ air in the refrigerating chamber is reduced to 0℃ ten times, which cannot melt the frost on the three quick-freezing chamber evaporator coils and the cooling fins, which is close to 2g after the compressor of the refrigerator runs once. The temperature reduction of the refrigerating chamber of the existing frosty refrigerator relies on a one-centimeter-diameter hole connecting the refrigerating chamber and the quick-freezing chamber, and the heat exchange is carried out by the convection of the hot air in the refrigerating chamber above 0℃ and the cold air in the quick-freezing chamber below 0℃. When the temperature of the refrigerating chamber exceeds 4℃, the compressor of the refrigerator is started, and the compressor stops running until the temperature of the refrigerating chamber is reduced to 0℃. The absolute humidity of the air in the refrigerating chamber is higher than that in the quick-freezing chamber, so when the air in the refrigerating chamber enters the quick-freezing chamber, part of the water vapor in the air will condense into water and fall on the three quick-freezing chamber evaporator coils and the cooling fins, and then further form frost on the three quick-freezing chamber evaporator coils and the cooling fins, consuming the refrigeration capacity of the refrigerator, and the heat released when 1g of water vapor forms frost is more than 400 cal. After the relative humidity of the air in the refrigerating chamber is reduced, the food in the refrigerating chamber will evaporate water vapor as a supplement, making the food dry and losing its freshness. SUMMARY

[0003] The air cooling defrosting device of the frostless refrigerator. The three evaporator coils of the quick freezing chamber are each surrounded by a compatible foam plastic heat preservation special-shaped square tube. The inlet of the evaporator coil is lower than the outlet, and the foam plastic heat preservation special-shaped square tube near the inlet of the evaporator coil 1 is wider and then gradually narrows. The foam plastic heat preservation special-shaped square tube is bonded by two special-shaped grooves, and there is a horizontal gap every certain distance. Two heat insulation cloth strips coated with rubber film are bonded together with the foam plastic heat preservation special-shaped square tube at the non-gap position. A vertical foam plastic heat preservation wide square tube connects the wide end of the three foam plastic heat preservation special-shaped square tubes in parallel. A sponge is inserted into the lower end of the vertical foam plastic heat preservation wide square tube, and then a drain pipe is connected. The outlet of the drain pipe is above the water collecting pool. The heat preservation pipe connected to the upper end of the vertical foam plastic heat preservation wide square tube is connected to the front end of the shaftless fan through a wind direction switch. A vertical foam plastic heat preservation narrow square tube connects the narrow end of the three foam plastic heat preservation special-shaped square tubes in parallel. The heat preservation pipe connected to the upper end of the vertical foam plastic heat preservation narrow square tube is connected to the upper side of the fresh-keeping chamber through an air outlet check valve. The lower end of the vertical foam plastic heat preservation narrow square tube is closed. The shaftless fan is composed of a single-phase synchronous shaftless motor, a clutch controlled by an electromagnet, and fan blades. The stator of the single-phase synchronous shaftless motor is provided with two electromagnet pawls, and the rotor of the single-phase synchronous shaftless motor is provided with two ratchet rings. The inner surface of the rotor of the single-phase synchronous shaftless motor is provided with fan blades. The heat preservation pipe connected to the rear end of the shaftless fan is connected to the right interface of the heat preservation tee. The heat preservation pipe connected to the upper interface of the heat preservation tee is connected to the lower side of the fresh-keeping chamber through a return air check valve. A vertical foam plastic heat preservation medium square tube is arranged between the vertical foam plastic heat preservation wide square tube and the vertical foam plastic heat preservation narrow square tube. The vertical foam plastic heat preservation medium square tube is connected to three positions of the quick freezing chamber. The lower end of the vertical foam plastic heat preservation medium square tube is closed. The heat preservation pipe connected to the upper end of the vertical foam plastic heat preservation medium square tube is connected to the lower interface of the heat preservation tee through a refrigeration check valve. The air outlet check valve, the return air check valve, and the refrigeration check valve use heat insulation cloth valve pieces coated with rubber film. One edge of the heat insulation cloth valve pieces coated with rubber film is fixed on the construction base. The outer surface of the heat insulation cloth valve pieces coated with rubber film is provided with an insulated heating wire with a rated voltage of 6V and a rated power of 1W.

[0004] A control method of air-blast defrosting device of frostless refrigerator. When compressor works, liquid refrigerant enters evaporator coil through expansion valve, liquid refrigerant gasifies in evaporator coil, absorbs gasification heat to reduce evaporator coil temperature. Insulated electric heating wire of air outlet one-way valve, return air one-way valve, refrigeration one-way valve is connected with 6V AC power. Electromagnetic pawl of single-phase synchronous shaftless motor stator rear end of shaftless fan 7 is electrified to press pawl to the ratchet on the ratchet ring of rotor rear end. Single-phase synchronous shaftless motor stator coil of shaftless fan is connected with 220V single-phase AC power, rotor can only reverse to blow air to the back, air outlet one-way valve opens, return air one-way valve opens, refrigeration one-way valve closes. 4℃ air in fresh-keeping room 4 enters foam plastic insulation special-shaped square tube through air outlet one-way valve, 4℃ air contacts frost on evaporator coil to release heat and become 0℃ air, water vapor in 4℃ air contacts frost on evaporator coil to release vaporization heat and become condensed water, frost on evaporator coil absorbs heat and melts into water, one gram of water vapor condenses into water, which can melt four grams of frost. 0℃ water in foam plastic insulation special-shaped square tube flows from high place to low place under the push of flowing air, wide mouth end of foam plastic insulation special-shaped square tube, then flows into vertical foam plastic insulation wide square tube, water flows into sponge at lower end of vertical foam plastic insulation wide square tube, sponge is soaked with water, then you stop air flow. Water passes through sponge under the action of gravity, then flows into water collecting pool from drain pipe.The air in the foamed plastic heat preservation special-shaped square tube is extracted by the axial fan through the air direction switch, and then is blown into the fresh-keeping chamber through the return air check valve. The negative pressure is generated on the horizontal gap of the foamed plastic heat preservation special-shaped square tube, and the heat insulation cloth strip coated with rubber film is pressed to the gap to close the gap, so that the cold air in the quick-freezing chamber cannot flow into the foamed plastic heat preservation special-shaped square tube. When the air in the foamed plastic heat preservation special-shaped square tube is extracted by the axial fan through the air direction switch, the air target of the air direction switch is turned to the air extraction direction, the air extraction contact is connected, and then the electromagnetic pawl at the rear end of the stator of the single-phase synchronous axial motor of the axial fan is stopped from being electrified, and the pawl is separated from the ratchet on the ratchet gear ring at the rear end of the rotor under the action of the reset spring. The insulation heating wire of the air outlet check valve, the return air check valve and the refrigeration check valve is stopped from being electrified by 6V alternating current. The temperature of the food in the fresh-keeping chamber is gradually reduced from 4℃ to 0℃, and then the stator coil of the axial fan is stopped from being electrified by 220V single-phase alternating current. The water vapor in the air in the fresh-keeping chamber enters the foamed plastic heat preservation special-shaped square tube to condense into water, so that the food in the fresh-keeping chamber loses moisture and becomes dry and not easy to mildew. The water vapor in the air in the quick-freezing chamber enters the foamed plastic heat preservation special-shaped square tube to condense into frost on the evaporator coil, so that the food in the quick-freezing chamber loses moisture and becomes dry and not easy to freeze together. BRIEF DESCRIPTION OF DRAWINGS

[0005] The application will be further specifically and concretely described below in combination with the drawings and specific embodiments.

[0006] Figure 1 is the structural principle diagram of the air-cooled defrosting device in the application.

[0007] Figure 2 is the structural schematic diagram of the evaporator coil and its accessories in the application. DETAILED DESCRIPTION

[0008] Figure 1 and Figure 2The device is used for air defrosting of frost-free refrigerator. Three evaporator coils 1 of quick-freezing chamber are each surrounded by a foam plastic heat-insulating profiled square tube 2. The inlet of evaporator coil 1 is lower than the outlet, and the foam plastic heat-insulating profiled square tube 2 near the inlet is wider and then gradually narrows. The foam plastic heat-insulating profiled square tube 2 is formed by bonding two profiled grooves, and there is a horizontal gap every certain distance. Two heat-insulating cloth strips with rubber film on the surface are bonded to the foam plastic heat-insulating profiled square tube 2 at the gap-free position. A vertical foam plastic heat-insulating wide square tube 3 connects the wide end of the three foam plastic heat-insulating profiled square tubes 2. A sponge 12 is inserted into the lower end of the vertical foam plastic heat-insulating wide square tube 3, and then a drain pipe 13 is connected. The outlet of the drain pipe 13 is above a water collecting pool 14. A heat-insulating pipe connected to the upper end of the vertical foam plastic heat-insulating wide square tube 3 is connected to the front end of a shaftless fan 7 through a wind direction switch 6. A vertical foam plastic heat-insulating narrow square tube 5 connects the narrow end of the three foam plastic heat-insulating profiled square tubes 2. A heat-insulating pipe connected to the upper end of the vertical foam plastic heat-insulating narrow square tube 5 is connected to the upper side of a fresh-keeping chamber through an air outlet check valve 11. The lower end of the vertical foam plastic heat-insulating narrow square tube 5 is closed. The shaftless fan 7 is composed of a single-phase synchronous shaftless motor, a clutch controlled by an electromagnet and fan blades. The stator of the single-phase synchronous shaftless motor is provided with two electromagnet pawls, and the rotor of the single-phase synchronous shaftless motor is provided with two ratchet rings. The inner surface of the rotor of the single-phase synchronous shaftless motor is provided with fan blades. A heat-insulating pipe connected to the rear end of the shaftless fan 7 is connected to the right interface of a heat-insulating tee 8. A heat-insulating pipe connected to the upper interface of the heat-insulating tee 8 is connected to the lower side of the fresh-keeping chamber through an air return check valve 9. A vertical foam plastic heat-insulating medium square tube 4 is arranged between the vertical foam plastic heat-insulating wide square tube 3 and the vertical foam plastic heat-insulating narrow square tube 5. The vertical foam plastic heat-insulating medium square tube 4 is connected to three positions of the quick-freezing chamber. The lower end of the vertical foam plastic heat-insulating medium square tube 4 is closed. A heat-insulating pipe connected to the upper end of the vertical foam plastic heat-insulating medium square tube 4 is connected to the lower interface of the heat-insulating tee 8 through a refrigeration check valve 10. The air outlet check valve 11, the air return check valve 9 and the refrigeration check valve 10 use heat-insulating cloth valve pieces coated with rubber film. The edge of the heat-insulating cloth valve pieces is fixed on the base. The outer surface of the heat-insulating cloth valve pieces is provided with insulated heating wires with rated voltage of 6V and rated power of 1W.

[0009] Figure 1 and Figure 2The control method of the air-blast defrosting device of a frostless refrigerator is shown. When the compressor is working, liquid refrigerant enters the evaporator coil 1 through the expansion valve. The liquid refrigerant is vaporized in the evaporator coil 1, absorbing heat of vaporization to lower the temperature of the evaporator coil 1. The insulated heating wires of the air outlet check valve 11, the return air check valve 9 and the refrigeration check valve 10 are connected to 6V AC power supply. The electromagnetic pawl at the front end of the stator of the single-phase synchronous shaftless motor of the shaftless fan 7 is energized to press the pawl against the ratchet on the front end ratchet ring of the rotor. The stator coil of the single-phase synchronous shaftless motor of the shaftless fan 7 is connected to 220V single-phase AC power supply. The rotor can only rotate forward to blow air forward. The air outlet check valve 11 is closed, the return air check valve 9 is closed, and the refrigeration check valve 10 is opened. The shaftless fan 7 draws air from the quick-freezing chamber through the refrigeration check valve 10, then through the air target of the air direction switch 6 into the foamed plastic heat-insulated special-shaped square tube 2 from the wide end of the foamed plastic heat-insulated special-shaped square tube 2, taking away the cold air near the evaporator coil 1. The water vapor in the air blown into the foamed plastic heat-insulated special-shaped square tube 2 releases heat of vaporization, condensing into frost on the evaporator coil 1. The cold air pushes the heat-insulated cloth strip covered with rubber film on the horizontal gap of the foamed plastic heat-insulated special-shaped square tube 2, entering the quick-freezing chamber to further freeze the food in the drawer of the quick-freezing chamber. The air target of the air direction switch 6 is turned to the blowing direction, and the blowing contact is connected. Then the electromagnetic pawl at the front end of the stator of the single-phase synchronous shaftless motor of the shaftless fan 7 is de-energized, and the pawl is separated from the ratchet on the front end ratchet ring of the rotor under the action of the return spring. The insulated heating wires of the air outlet check valve 11, the return air check valve 9 and the refrigeration check valve 10 are de-energized. After the compressor stops working, there is still liquid refrigerant in the evaporator coil 1 that has not been vaporized. The rotor of the shaftless fan 7 continues to rotate forward for three minutes and then stops. Then the insulated heating wires of the air outlet check valve 11, the return air check valve 9 and the refrigeration check valve 10 are connected to 6V AC power supply. The electromagnetic pawl at the rear end of the stator of the single-phase synchronous shaftless motor of the shaftless fan 7 is energized to press the pawl against the ratchet on the rear end ratchet ring of the rotor. The stator coil of the single-phase synchronous shaftless motor of the shaftless fan 7 is connected to 220V single-phase AC power supply. The rotor can only rotate backward to blow air backward. The air outlet check valve 11 is opened, the return air check valve 9 is opened, and the refrigeration check valve 10 is closed. The 4℃ air in the fresh-keeping chamber 4 enters the foamed plastic heat-insulated special-shaped square tube 2 through the air outlet check valve 11. The 4℃ air contacts the frost on the evaporator coil 1 to release heat and become 0℃ air. The water vapor in the 4℃ air contacts the frost on the evaporator coil 1 to release heat of vaporization and become condensed water. The frost on the evaporator coil 1 absorbs heat and melts into water. One gram of water vapor condenses into water, which can melt four grams of frost. The 0℃ water in the foamed plastic heat-insulated special-shaped square tube 2 flows from high to low under the push of the flowing air, then flows into the vertical foamed plastic heat-insulated wide square tube 3, and then flows into the sponge 12 at the lower end of the vertical foamed plastic heat-insulated wide square tube 3. The sponge 12 stops air flow after being soaked in water. The water flows through the sponge 12 under the action of gravity, and then flows into the water pool 14 from the drain pipe 13.The shaftless fan 7 draws out 0℃ air in the foamed plastic heat preservation special-shaped square tube 2 through the air direction switch 6 and blows it into the fresh-keeping chamber through the return air check valve 9, so as to generate negative pressure on the horizontal gap of the foamed plastic heat preservation special-shaped square tube 2, press the heat insulation cloth strip coated with rubber film on the gap to the gap, and seal the gap, so that the cold air in the quick-freezing chamber cannot flow into the foamed plastic heat preservation special-shaped square tube 2. When the shaftless fan 7 draws out 0℃ air in the foamed plastic heat preservation special-shaped square tube 2 through the air direction switch 6, the air target of the air direction switch 6 swings to the air exhaust direction, the air exhaust contact is connected, and then the electromagnetic pawl at the rear end of the stator of the single-phase synchronous shaftless motor of the shaftless fan 7 is stopped from being electrified, and the pawl is separated from the ratchet on the ratchet gear ring at the rear end of the rotor under the action of the reset spring. The 6V alternating current is stopped from being input into the insulating heating wire of the air exhaust check valve 11, the return air check valve 9 and the refrigeration check valve 10. The temperature of the food in the fresh-keeping chamber is gradually reduced from 4℃ to 0℃, and then the 220V single-phase alternating current is stopped from being input into the stator coil of the shaftless fan 7. The water vapor in the air in the fresh-keeping chamber condenses into water in the foamed plastic heat preservation special-shaped square tube 2, so that the food in the fresh-keeping chamber loses moisture and becomes dry and not easy to mildew. The water vapor in the air in the quick-freezing chamber condenses into frost on the evaporator coil 1 in the foamed plastic heat preservation special-shaped square tube 2, so that the food in the quick-freezing chamber loses moisture and becomes dry and not easy to freeze together.

Claims

1. A defrosting device for a frost-free refrigerator, characterized in that: Each of the three evaporator coils (1) in the blast freezer is fitted with a matching foam plastic insulated shaped square tube (2). The inlet of the evaporator coil (1) is low and the outlet is high. The foam plastic insulated shaped square tube (2) near the inlet of the evaporator coil (1) is wider and then gradually narrows. The foam plastic insulated shaped square tube (2) is made of two shaped grooves glued together. There is a horizontal gap at every interval. Two heat-insulating cloth strips with rubber film on the surface are glued together with the foam plastic insulated shaped square tube (2) where there is no gap.

2. The air-cooled defrosting device for a frost-free refrigerator according to claim 1, characterized in that: A vertical foam plastic insulation wide square tube (3) connects the wide ends of the three foam plastic insulation special-shaped square tubes (2) together. A piece of sponge (12) is inserted into the lower end of the vertical foam plastic insulation wide square tube (3), and then a drain pipe (13) is connected. The outlet of the drain pipe (13) is above the water collection tank (14). The insulation pipe connected from the upper end of the vertical foam plastic insulation wide square tube (3) is connected to the front end of the shaftless fan (7) through the air direction switch (6). A vertical foam plastic insulation narrow square tube (5) connects the narrow ends of the three foam plastic insulation special-shaped square tubes (2) together. The insulation pipe connected from the upper end of the vertical foam plastic insulation narrow square tube (5) is connected to the upper side of the fresh food compartment through the air outlet one-way valve (11). The lower end of the vertical foam plastic insulation narrow square tube (5) is closed.

3. The air-cooled defrosting device for a frost-free refrigerator according to claim 1 or claim 2, characterized in that: The shaftless fan (7) consists of a single-phase synchronous shaftless motor, an electromagnet-controlled clutch, and fan blades. The stator of the single-phase synchronous shaftless motor is equipped with an electromagnetic pawl at each of its two ends, and the rotor of the single-phase synchronous shaftless motor is equipped with a ratchet ring at each end. The inner surface of the rotor of the single-phase synchronous shaftless motor is equipped with fan blades.

4. The air-cooled defrosting device for a frost-free refrigerator according to claim 1, 2, or 3, characterized in that: The insulation pipe extending from the rear end of the shaftless fan (7) is connected to the right interface of the insulation tee (8). The insulation pipe extending from the upper interface of the insulation tee (8) is connected to the lower side of the fresh-keeping compartment via the return air check valve (9). A vertical foam plastic insulation square tube (4) is installed between the vertical foam plastic insulation wide square tube (3) and the vertical foam plastic insulation narrow square tube (5). The vertical foam plastic insulation square tube (4) is connected to three positions of the quick-freezing compartment. The lower end of the vertical foam plastic insulation square tube (4) is closed. (4) The insulation pipe that goes out from the top is connected to the lower interface of the insulation tee (8) via the refrigeration check valve (10). The outlet check valve (11), return check valve (9), and refrigeration check valve (10) use heat insulation cloth valve plates coated with rubber film. One edge of the heat insulation cloth valve plate coated with rubber film is fixed on the building base. The outer surface of the heat insulation cloth valve plate coated with rubber film of the outlet check valve (11), return check valve (9), and refrigeration check valve (10) is equipped with an insulating heating wire. The rated voltage of the insulating heating wire is 6V and the rated power is 1W.

5. The control method for the air-cooled defrosting device of a frost-free refrigerator according to claim 1, 2, 3, or 4, characterized in that: When the compressor is working, the liquid refrigerant enters the evaporator coil (1) through the expansion valve. In the evaporator coil (1), the liquid refrigerant vaporizes and absorbs the heat of vaporization to reduce the temperature of the evaporator coil (1). 6V AC power is supplied to the insulated heating wires of the outlet air check valve (11), return air check valve (9), and refrigeration check valve (10), energizing the electromagnetic pawl at the front end of the stator of the single-phase synchronous shaftless motor of the shaftless fan (7) and pressing the pawl against the ratchet teeth on the front end of the rotor ratchet ring. 220V single-phase AC power is supplied to the stator coil of the single-phase synchronous shaftless motor of the shaftless fan (7). The rotor can only blow air in the forward direction. The outlet air check valve (11) is closed, the return air check valve (9) is closed, and the refrigeration check valve (10) is open. The air from the shaftless fan (7) passes through the refrigeration check valve (10). 10) The air in the freezer is extracted and then passes through the air target of the air direction switch (6) into the foam plastic insulated special-shaped square tube (2) through the wide end. The cold air near the evaporator coil (1) is carried away. The water vapor in the air blown into the foam plastic insulated special-shaped square tube (2) releases heat of vaporization and condenses into frost on the evaporator coil (1). The cold air pushes open the heat insulation strip coated with rubber film covering the horizontal gap of the foam plastic insulated special-shaped square tube (2) and enters the freezer to further freeze the food in the freezer drawer. The air target of the air direction switch (6) is swung to the blowing direction and the blowing contact is connected. Then the electromagnetic pawl at the front end of the stator of the single-phase synchronous shaftless motor of the shaftless fan (7) is stopped from being energized. The pawl is in the reset spring. Under the action of the spring, the ratchet on the front ratchet ring of the rotor is disengaged, and the insulated heating wires of the air supply check valve (11), return air check valve (9), and refrigeration check valve (10) are stopped. After the compressor stops working, there is still liquid refrigerant in the evaporator coil (1) that has not been vaporized. The rotor of the shaftless fan (7) continues to rotate forward for three minutes and then stops rotating. Then, the insulated heating wires of the air supply check valve (11), return air check valve (9), and refrigeration check valve (10) are energized to the electromagnetic pawl at the rear end of the stator of the single-phase synchronous shaftless motor of the shaftless fan (7), pressing the pawl against the ratchet on the rear end ratchet ring of the rotor. 220V single-phase AC power is supplied to the stator coil of the single-phase synchronous shaftless motor of the shaftless fan (7), and the rotor can only rotate in reverse. When the air blows backward, the outlet one-way valve (11) opens, the return one-way valve (9) opens, and the refrigeration one-way valve (10) closes. The 4°C air in the preservation chamber enters the foam plastic insulated special-shaped square tube (2) through the outlet one-way valve (11). The 4°C air comes into contact with the frost on the evaporator coil (1) and releases heat to become 0°C air. The water vapor in the 4°C air comes into contact with the frost on the evaporator coil (1) and releases heat of vaporization to become condensate. The frost on the evaporator coil (1) absorbs heat and melts into water. One gram of water vapor condenses into water and can melt four grams of frost. The 0°C water in the foam plastic insulated special-shaped square tube (2) flows from high to low under the push of the flowing air, through the wide end of the foam plastic insulated special-shaped square tube (2), and then flows into the vertical foam plastic insulated wide square tube (3).Water flows into the lower end of the vertical foam plastic insulation square tube (3) and is stuffed into the sponge (12). After the sponge (12) is soaked in water, it prevents air flow. The water passes through the sponge (12) under gravity and then flows into the water collection tank (14) from the drain pipe (13). The shaftless fan (7) draws out the 0℃ air in the foam plastic insulation square tube (2) through the air direction switch (6) and blows it into the preservation chamber through the return air one-way valve (9). It generates negative pressure on the horizontal gaps on the foam plastic insulation square tube (2) and presses the heat insulation strip coated with rubber film on the gaps to the gaps to seal them and prevent the cold air in the freezer from flowing into the foam plastic insulation square tube (2). When the axial fan (7) extracts 0℃ air from the foam plastic insulated square tube (2) via the air direction switch (6), the air target of the air direction switch (6) swings towards the exhaust direction, the exhaust contact is connected, and then the electromagnetic pawl at the rear end of the stator of the single-phase synchronous shaftless motor of the shaftless fan (7) is energized. Under the action of the return spring, the pawl leaves the ratchet on the ratchet ring at the rear end of the rotor, and the insulated heating wire of the exhaust one-way valve (11), return one-way valve (9), and refrigeration one-way valve (10) is stopped from receiving 6V AC power. The food temperature in the fresh food compartment gradually decreases from 4℃ to 0℃, and then the 220V single-phase AC power is stopped from being supplied to the stator coil of the shaftless fan (7).

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