JPH0726782B2 - Defroster for cold air circulation type showcase - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a defrosting method for a cold air circulation type showcase intended for an open showcase for refrigeration handling fresh food products such as meat and fresh fish.

[Conventional technology]

Various defrosting methods such as hot gas defrosting, heater defrosting, off-cycle defrosting, and air defrosting have been known as defrosting methods for a cooler built into this type of showcase. The defrosting is periodically performed by timer control or the like while sewing between the cold insulation operations.

On the other hand, in the showcase, if the cooling operation of the cooler is interrupted during the defrosting period, the air that has been heated by the defrosting heat circulates inside the storehouse, raising the temperature inside the storehouse, which causes the display inside the storehouse. There is a risk that the product temperature of such products will rise and the quality of fresh food products will deteriorate.

Therefore, as a measure to prevent the product humidity from rising during defrosting as described above, two coolers are placed side by side in the cold air circulation path and connected to the condensing unit of the refrigerator to defrost each cooler. And the liquid refrigerant of high temperature and high pressure sent out from the condensing unit is directly introduced into the cooler on the defrosting side during defrosting while performing defrosting of the liquid refrigerant. The same applicant has already proposed a defrosting method in which the supercooled refrigerant generated from the above is supplied to the other cooler to continue the cooling operation.

Next, the defrosting method for the showcase proposed above will be described with reference to FIGS. First, FIG. 5 shows a structure of a cold air circulation type showcase, 1 is a case body of a showcase having an open front surface, 2 is an outer box, 3 is an inner box, 4 is a product display room in the warehouse, Inner and outer two layers of inner and outer cool air circulation paths 5 and 6 are defined between the outer box 2 and the inner box 3 via a partition wall. Here, the inner fan 7 is installed in the inner side cold air circulation path 5. In addition, two coolers 8A and 8B arranged side by side are installed, and an outer fan 9 is installed in the cool air circulation path 6 on the outer side. In addition, 10 is an air damper installed at the boundary between the coolers 8A and 8B to block the ventilation outlet of either one of the coolers, 11 is the ceiling inside the warehouse, and the interior lighting installed on each stage of the product display shelf. is there.

In such a showcase, each cooler 8A, 8B is operated during cold storage operation.
Cooling operation is performed together, and the cool air circulation paths 5 and 6 in the refrigerator circulate the cool air indicated by the arrows A and B, respectively, to form a cool air curtain of two layers inside and outside at the front opening of the case body 1, It keeps the products displayed in the refrigerator cool by blocking the entry of outside air.

On the other hand, the refrigerant circuit including the coolers 8A and 8B is as shown in FIG. In the figure, reference numeral 12 is a condensing unit of a refrigerator, and the two coolers 8A and 8B are connected in parallel to the condensing unit 12 by piping. Further, 13A and 13B are expansion valves, 14A and 14B are bypass pipes bypassing the coolers 8A and 8B and expansion valves 13A and 13B, 15A and 15B are check valves, and 16 is a refrigerant inserted upstream of the cooler. Solenoid valve on the inlet side, 17A, 17B are solenoid valves inserted on the outlet side, 18A, 18B are bypass lines 14A, 14B
It is a solenoid valve inserted in.

In such a refrigerant circuit, the air damper 10 shown in FIG. 5 is opened and the solenoid valves 16, 17A and 17B shown in FIG. 6 are opened to operate the condensing unit 12 during the cold insulation operation. As a result, the refrigerant flows through the expansion valves 13A and 13B as shown by the solid arrows and is cooled by the cooler.
8A, 8B, where it evaporates and cools the inner cold air A.

On the other hand, when a predetermined cool operation time elapses and then shifts to defrosting, the coolers 8A and 8B are alternately defrosted one by one by the liquid refrigerant defrosting method described below. First, in order to defrost the cooler 8A, the air damper 10 (Fig. 5) is tilted to the cooler 8A side to block the ventilation outlet of the cooler 8A, and the solenoid valves 16 and 17A are turned on from the cool operation state. Close and switch solenoid valve 18A to open. This allows the refrigerant to flow in the refrigerant circuit as indicated by the dotted arrow. That is, the high-temperature, high-pressure liquid refrigerant sent from the condensing unit 12 is first introduced into the cooler 8A via the bypass pipe line 14A without passing through the expansion valve,
The frost attached to the cooler 8A is melted and defrosted by the heat of the liquid refrigerant. Further, in this defrosting process, the liquid refrigerant becomes a supercooled state (temperature drop) and flows out from the cooler 8A, and then the expansion valve 13
After passing through B, it enters the cooler 8B, where it evaporates and cools the cooler 8B. In this case, the refrigerating capacity of the cooler 8B is increased by the amount of the supercooled refrigerant as compared with that in the steady cool operation. As a result, while one of the coolers 8A is being defrosted, the cooling operation can be continued with the other of the coolers 8B, and the rise of the internal cold storage temperature and the product temperature can be suppressed.

When the defrosting of the cooler 8A is completed, the defrosting of the cooler 8B is subsequently performed. Note that the defrosting in this case is the same as the above-mentioned procedure, and the cooling device 8A is cooled while the high-temperature, high-pressure liquid refrigerant is introduced to perform defrosting of the liquid refrigerant.

[Problems to be Solved by the Invention]

By the way, the defrosting method described above has the effect of defrosting each cooler while suppressing the quality increase of the product as long as the showcase is operated under normal ambient temperature conditions. In the low winter season, when the store with the showcase is closed and defrosting is performed at night, the following problems will occur.

In other words, at night after the store is closed in winter, all the interior lighting of the showcase is off, and the ambient temperature also drops significantly, so the refrigeration load of the showcase is significantly reduced compared to the daytime operation. It becomes a state. For this reason, when performing night refrigerant defrosting during defrosting as described above, the refrigerant is supercooled in the process of flowing through the defrosting-side cooler,
The cooler on the cooling operation side exerts a refrigerating capacity more than the refrigerating load at that time to cool the inside of the refrigerator more than necessary, and as a result, the product becomes too cold and the fresh product freezes. Moreover, if the store opens on the next day, the ambient temperature will rise again during the day and the internal lighting will also turn on, so the heat from these items will cause the frozen products to thaw during the night.

By the way, when fresh meat, fresh fish, etc. are thawed once frozen, the soup called "drip" comes out and the freshness of the meat rapidly declines. For this reason, if the displayed product in the showcase that is frozen during the night is thawed the next day as described above, it may cause a problem in the cold storage management of the product, which lowers the product value. Become.

In the showcase, if the internal cold storage temperature becomes too cold in the normal cold storage operation, the internal cold storage temperature is adjusted by stopping the operation of the refrigerator by the operation of the thermostat. In the liquid refrigerant defrosting method described, since defrosting also stops when the refrigerator is stopped during defrosting, during this defrosting period, the thermostat for controlling the internal temperature is locked in an inoperative state. As a result, the above-mentioned operation state of the inside of the refrigerator being too cold may occur.

The present invention has been conceived in view of the above points. As described above, the defrosting method of alternately defrosting the liquid refrigerant between the two coolers is used together, and the ambient temperature of the showcase is also used. It is an object of the present invention to provide a defrosting method for a cool air circulation type showcase, which can defrost the cooler while preventing the product from freezing at night during the winter season when the temperature decreases and after closing the store.

[Means for Solving the Problems]

In order to solve the above problems, in the defrosting method of the present invention, for two coolers arranged side by side in the cold air circulation path in the refrigerator,
When defrosting while operating under normal ambient temperature conditions, liquid refrigerant is defrosted alternately one by one.On the other hand, when defrosting at night after the store is closed in winter, the interior lighting of the showcase is defrosted. In this case, the supply of the refrigerant to each cooler is stopped under the condition that the light is turned off and the ambient outside air temperature is lowered, and the defrost of the cooler is switched from liquid refrigerant defrost to off-cycle defrost to perform defrost.

In addition, the inside and outside 2
For a showcase in which a layered air curtain is blown out, liquid refrigerant defrosting is alternately performed on the two coolers in the same manner as above, and defrosting is performed at night after the store is closed in winter. In case of defrosting, when the defrosting is performed, the interior lighting of the showcase is turned off and the refrigerant supply to each cooler is stopped under the condition that the ambient outside temperature is lowered, and the fan of the outer cool air circulation path is reversed to turn the cooler on. The defrosting is switched from the liquid refrigerant defrosting to the air defrosting in which the outside air is introduced by the reversing fan.

[Action]

In the above, as means for switching the defrosting from liquid refrigerant defrosting to off-cycle defrosting or air defrosting, a relay operating in conjunction with blinking of the illumination switch of the internal lighting,
And an outdoor temperature thermostat that operates under the condition that the ambient temperature around the showcase drops below the set temperature, and based on these operating signals, the opening / closing control of the solenoid valve inserted in the refrigerant circuit of the refrigerator including the cooler, In addition, control the forward and reverse rotation of the outer fan.

Here, when defrosting is performed at night or in the winter when the ambient temperature is low and when the store is closed, the defrosting is switched to off-cycle defrosting under the conditions of turning off the illumination lamp and lowering the ambient outside temperature as described above. The frost adhering to the surface of the cooler is defrosted by the circulating air that passes through the cool air circulation path in the non-cooled state in which the supply of the refrigerant to the cooler is stopped. Therefore, defrosting can be performed while preventing the inside of the refrigerator from being overcooled due to supercooling of the refrigerant, which has been a problem in the liquid refrigerant defrosting method described in FIG.

Further, particularly for the two-layer cold air circulation type showcase, the cooling air supply to each cooler is stopped, and the outer fan is further reversed to switch to the air defrosting, so that the cool air outlet of the outer cold air circulation path. After the outside air sucked from around the showcase circulates in the opposite direction through the outer cold air circulation path, it is taken into the inner cold air circulation path adjacent to the cold air suction port and ventilates the cooler. Therefore, as in the case of the above-mentioned off-cycle defrosting, it is possible to effectively prevent defrosting of the inside of the refrigerator while effectively utilizing the heat retained by the outside air while preventing overcooling in the refrigerator.

〔Example〕

1 to 4 show an embodiment of the present invention. FIG. 1 is a defrosting control circuit diagram for switching the defrosting of a cooler to liquid refrigerant defrosting / off-cycle defrosting, and FIG. 2 is As an application example of FIG. 1, a defrosting control circuit system diagram when a plurality of showcases are installed in series at the same place, and FIG. 3 switches defrosting of a cooler to liquid refrigerant defrosting / air defrosting. Defrosting control circuit diagram for 2-layer air curtain type cold air circulation type showcase,
FIG. 4 is a ventilation state diagram of the inside of the refrigerator during air defrosting according to the method of FIG. 3, and in FIGS. 1 to 4, the same parts corresponding to FIGS. I am doing it.

First, in FIG. 1, reference numeral 19 denotes a defrost controller incorporated in a showcase. Inside the controller 19, the showcase is switched from cold-keeping operation to defrost by timer control or the like, and then shown in FIG. Solenoid valves 16 and 17 of refrigerant circuit
A solenoid valve control circuit 20 for controlling opening / closing of A, 17B, 18A, 18B is provided. In addition, 21 is a lighting switch inserted in the power supply circuit of the interior lighting 11, 11 is an auxiliary relay (X1) that detects the blinking of the lighting 11 in conjunction with the lighting switch, 23 is the ambient temperature of the showcase The outside temperature thermostat that operates when the temperature falls below (about 10 to 15 ° C), 24 is its auxiliary relay (X2), and the operation signals of the auxiliary relays 22 and 24 are supplied to the solenoid valve control circuit 20 of the controller 19 described above. Each relay contact is incorporated in the solenoid valve control circuit so as to switch the defrosting from liquid refrigerant defrosting to off-cycle defrosting.

Next, the defrosting operation of the showcase as described above will be described. First, under normal ambient temperature conditions and in a state where the internal lighting 11 is turned on and the showcase is operating, each cooler is controlled by the timer incorporated in the controller 19 as described in FIG. 8A and 8B are alternately defrosted by the liquid refrigerant defrosting method in a cycle of a predetermined time.

On the other hand, at night in winter, when the store is closed, the ambient temperature drops and the lamp 11 is also turned off. In this state, the lighting-off detection signal and the ambient temperature decrease detection signal are input to the controller 19 via the auxiliary relays 22 and 24 in FIG. When the showcase shifts from the cold insulation operation to the defrosting under this condition, the controller 19 closes the solenoid valves 16, 18A, 18B among the solenoid valves shown in FIG. , 17
Switch B to the open state. Therefore, from the state where the refrigerant was flowing through the coolers 8A, 8B during the cold insulation operation, the refrigerant inflow to each cooler is blocked, and at the same time, the refrigerant remaining in the cooler is returned to the condensing unit 12 through the return line. After being collected, the condensing unit 12 is shut down by the operation of the low pressure switch attached to the compressor.

Further, in this state, the refrigerant supply to the coolers 8A and 8B is cut off, and no cooling is performed because there is no refrigerant inside each cooler. On the other hand, in the cool air circulation path 5 shown in FIG. Air circulation ventilation by 7 continues. Therefore, the coolers 8A and 8B are in the off-cycle defrost state,
As a result, the temperature of the cooler approaches the temperature of the air passing through it, and when the air temperature rises above 0 ° C., the frost adhering to the surface of the cooler is melted and removed. If defrosting progresses and the temperature of the cooler rises to the preset defrosting end temperature (about 5 ° C), defrosting is released by the defrosting end thermostat signal and the showcase is kept cool again. Return to driving.

Fig. 2 shows a system diagram of the defrost control circuit when multiple showcases are connected and installed in the same place, and each showcase of each group indicated by I, II, and III is equipped. One outdoor temperature thermostat 23 is commonly connected to the controller 19. This simplifies the defrosting control circuit, and makes it possible to switch the showcases I to III of the respective bases to off-cycle defrosting in synchronization.

Next, FIGS. 3 and 4 show another embodiment of the defrosting method of the present invention for a two-layer cold air circulation type showcase. First of all
In the defrosting control circuit shown in the figure, the controller 19 includes a solenoid valve control circuit 20 described in the previous embodiment (FIG. 1), a fourth
The outer fan 9 in the figure is provided with a fan control circuit 25 that controls switching between normal rotation and reverse rotation. Here, as with the solenoid valve control circuit 20, the auxiliary relay 22 and the outside temperature thermostat 23, which are inserted in the lighting circuit, are provided. Auxiliary relay inserted in the circuit
Each of the 24 relay contacts is incorporated.

In such a defrosting control circuit, first, under normal ambient temperature conditions, and when the showcase is operated with the internal lighting lamp 11 turned on, the defrosting control circuit is incorporated in the controller 19 as in the embodiment of FIG. By the control of the timer, the coolers 8A and 8B are alternately defrosted by the liquid refrigerant defrosting method in a cycle of a predetermined time as described in FIG.

On the other hand, when the showcase shifts from the cold insulation operation to the defrosting in the closed state at night in winter when the ambient temperature is lowered and the illumination lamp 11 is off, the solenoid valve control circuit similar to the embodiment of FIG. 20 controls each solenoid valve so as to stop the refrigerant supply to the coolers 8A and 8B, and at the same time, the fan control circuit 25 causes the outer fan 9 installed in the outer cool air circulation path 6 in the refrigerator to rotate from the normal rotation to the reverse rotation. Switch and start defrosting air as described below.

That is, when the air is defrosted, the ventilation state inside the refrigerator is shown in FIG. 4, and the outer cold air circulation path 6 is shown by an arrow B _O in FIG. Air flows in the opposite direction to B. Therefore, the air flow blown from the cool air outlet of the inner cool air circulation path 5 on the front side of the case body 1
_AO forms an air curtain on the front surface of the case body 1, and a part of it merges with the outside air sucked from around the showcase and is sucked from the cold air outlet of the outer cold air circulation path 6 and inside the outer cold air circulation path 6. After circulating, the air is once blown out from the cool air suction port, and is merged with the air curtain on the side of the inner cool air circulation path 5 flowing down the front surface of the case body 1 so that the air is sucked into the inner cool air circulation path 5. That is, while forming an air curtain on the front surface of the case body 1, the outside air sucked from the periphery of the showcase circulates in the outer cool air circulation path 6 and then merges with the air curtain to be positively taken into the inner cool air circulation path 5. Like Moreover, the outside air temperature is higher than the cooling temperature inside the refrigerator, so that the frost adhering to the coolers 8A and 8B is defrosted early by the heat retained by the outside air. Further, during this defrosting period, the air curtain is blown off and formed on the front surface of the case main body 1 though it is incomplete, so that the heat of outside air entering the product display chamber 4 is prevented, and the product temperature rise can be suppressed. .

〔The invention's effect〕

Since the defrosting method of the present invention is configured as described above, it has the following effects.

That is, when defrosting is performed at night during winter when the refrigeration load is reduced, or in the operating state after the store is closed, liquid refrigerant defrosting that is performed under normal ambient temperature conditions, off-cycle defrosting, or air that is generated by reversing the outer fan is used. By switching to defrosting, the problems of overcooling of the refrigerator and product freezing due to supercooling of the refrigerant, which has been a problem in liquid refrigerant defrosting under these conditions, are solved.
The frost adhering to the cooler can be satisfactorily defrosted while preventing the product from freezing, and thus, an excellent effect of maintaining the product quality of fresh food and the like can be exhibited.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a defrosting control circuit diagram for switching the defrosting of a cooler to liquid refrigerant defrosting / off-cycle defrosting, and FIG. 2 is As an application example of FIG. 1, a defrosting control circuit system diagram when a plurality of showcases are installed in series at the same place, and FIG. 3 is a cooler for a two-layer air curtain type cold air circulation type showcase. Defrost control circuit diagram that switches defrost to liquid refrigerant defrost / air defrost
FIG. 4 is a ventilation state diagram inside the refrigerator during air defrosting by the method of FIG. 3, FIG. 5 is a cross-sectional view of a configuration of a cold air circulation type showcase showing ventilation conditions inside the refrigerator in a cold insulation operation state, and FIG. FIG. 4 is a refrigerant circuit diagram of a refrigerator showing a liquid refrigerant defrosting method that has been conventionally performed. In each figure, 1: Showcase case body, 5: Inner cold air circulation path, 6:
Outer cold air circulation circuit, 7: Inner fan, 8A, 8B: Cooler, 9:
Outer fan, 11: Internal lighting, 12: Condensing unit for refrigerator, 13A, 13B: Expansion valve, 14A, 14B: Bypass line, 16, 17A, 17B, 18A, 18B: Solenoid valve, 19: Controller , 2
0: Solenoid valve control circuit, 21: Lighting switch, 22, 24: Auxiliary relay, 23: Outside temperature thermostat, 25: Outer fan control circuit.

Front page continuation (72) Inventor Katsuhisa Suzuki 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (56) Reference JP-A-60-191171 (JP, A) JP-A-61- 15062 (JP, A) JP-A-57-108576 (JP, A)

Claims (2)

[Claims] 1. A cooler circulation path of a showcase is provided with two coolers arranged side by side together with a fan, and defrosting of each cooler is periodically and alternately performed. A plurality of high-temperature, high-pressure liquid refrigerants are directly introduced into the cooler to perform defrosting of the liquid refrigerant, and the supercooled refrigerant discharged from the cooler is supplied to the other cooler to continue the cooling operation. In the cold air circulation type showcase, when the defrosting was performed, the internal lighting was turned off, and a decrease in the ambient outside temperature was detected by the outside temperature thermostat, which is provided in common for multiple showcases and detects the ambient outside temperature. Conditioned to stop the supply of refrigerant to each cooler, switch from the liquid refrigerant defrost to off-cycle defrost, equipped with a control means for simultaneously performing defrosting of each cooler, cold air circulation Shape showcase defroster. 2. A cooler having two inner and outer cool air circulation paths in a compartment and two inner and outer air curtains blown to form a showcase, and two coolers are arranged side by side in the inner cool air circulation path. In addition, while performing defrosting of each cooler alternately one by one, at the time of defrosting, a high-temperature, high-pressure liquid refrigerant is directly introduced into the cooler on the defrosting side to perform defrosting of the liquid refrigerant while In a plurality of cool air circulation type showcases that supply the supercooled refrigerant that has come out to the other cooler to continue the cooling operation, when the defrosting is performed, the interior lighting lamp of the showcase is turned off, The cooling air supply to each cooler is stopped and the fan in the outer cold air circulation path is rotated reversely on condition that the decrease in the ambient temperature is detected by the ambient temperature thermostat that is commonly provided in the showcases. Remove the liquid refrigerant It switched to air defrosting for introducing outside air by reversing the fan from defrosting device of the cool air circulation type showcases, characterized in that it comprises a control means to perform the defrosting of the cooler simultaneously.