JPH0627604B2 - How to defrost a frozen / refrigerated open showcase - Google Patents

Description

Description: TECHNICAL FIELD The present invention is provided with inner and outer passage winds so as to form a decompression air curtain in an opening during a cooling operation, and an outer ventilation passage is provided during defrosting. The present invention relates to a defrosting method for a cold air circulation type freezer-refrigerating open showcase, which defrosts the outside air introduced so as to flow back into the inner ventilation passage.

[Prior art and its problems]

As this kind of open showcase, a multistage type as shown in FIG. 4 is known. In FIG. 4, a main body case 1 having an opening 1a for taking out a product on the front surface is an outer box 2 formed of a heat insulating wall and an inner box 3 provided with an appropriate gap between the outer box 2 and the outer box 2. A display room 5 is formed inside the inner box 3 and is divided into a plurality of stages by shelf plates 4.
Further, a partition wall 6 is provided between the outer box 2 and the inner box 3 to divide the gap into two, and an inner ventilation path 7 and an outer ventilation path 8 are formed. Both ends of the inner ventilation passage 7 have openings 1a.
Upper and lower sides of the outlet 7a and the inlet 7b, respectively, and the both ends of the outer ventilation passage 8 are respectively the outlet 7a and the inlet 7b.
An outlet 8a and an inlet 8b are formed on the outer side of and adjacent to b. The air outlets 7a and 8a are equipped with an air rectifying body 9 having honeycomb-shaped ventilation holes, and a cooler 11, a fan 12, and a defrost heater 21 are provided in the inner communication passage 7.
However, a fan 13 is arranged in the outer ventilation passage 8.

In this open showcase, during the cooling operation, the indoor air is circulated by the fan 12 in the direction of the arrow A and circulated in the direction of the arrow A, and is cooled by the cooler 11 to become cold air, which is blown out from the air outlet 7a. Opening 1a
In addition, the air curtain 15 for shutting off the inside of the display room 5 from the outside air is formed and the inside of the display room 5 is cooled. Further, an air curtain 16 is formed on the outside so as to protect the air curtain 15 by the indoor air that circulates and circulates in the outside air passage 8 in the direction of arrow B by the fan 13, so that the inside of the display room 5 can be cooled and cooled more efficiently. It Further, during the defrosting operation, the operation of the cooler 11 is stopped and the defrosting heater 21 is energized. The defrosting removes the frost formed on the cooler 11 by being heated by the air defrosting heater 21 sucked from the suction port 7b by the fan 12. And when the cooler outlet air temperature, or the temperature of the whole condenser 11 has reached the temperature of the defrost ending temperature T _2, and terminate the defrosting in sensing such defrosting thermo.

In this case, the temperature of the cooler 11 gradually rises from below due to the heated air, and the defrosting is performed while melting the frost. Therefore, at the end of the defrosting, a large temperature difference occurs between the upper side and the lower side of the cooler 11. . When the next cooling operation is started, the air flowing through the inner ventilation passage 7 is cooled, but it takes time for the entire cooler 11 to drop to a predetermined temperature.
Since the product temperature in the display room 5 rises for a certain period of time even at the beginning of the cooling operation, there is a problem that the product is damaged and the storage period is shortened and product loss occurs. Note that FIG. 2 is an explanatory diagram showing the above-mentioned temperature change characteristic.

[Object of the Invention]

In view of the above points, the present invention provides a defrosting method for a cold air circulation type freezing / refrigerating open showcase that shortens the defrosting time during defrosting operation and suppresses the temperature rise of products to maintain freshness for a long time. With the goal.

[Main points of the invention]

The present invention achieves this object by using different defrosting methods at the start of defrosting and before the end of defrosting. That is, at the start of defrosting, the fan in the outer ventilation passage is rotated in the reverse direction and the fan in the inner ventilation passage is rotated at a high speed to dissolve the frost in the cooler by the outside air introduced into the inner ventilation passage. Before the end, take the method of defrosting the air by switching the outer fan to normal rotation and the inner fan to low speed rotation, and when using a defrost heater together, synchronize it only when the outer ventilation fan reversely rotates. It is the one.

Example of Invention

Hereinafter, the present invention will be described in detail with reference to the drawings showing an embodiment of the present invention. FIG. 1 shows the flow of air at the start of defrosting according to the present invention. The same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted. FIG. 3 shows the inner fan 12,
The wiring diagram of the outer side fan 13 and a defrost heater circuit is shown. The operation set value of the heating prevention thermostat 20 is set at a temperature lower than the defrosting end temperature T ₂ . Also, the inner fan 12 has a low speed,
The fan that can be switched at high speed and the outer fan 13 are reversible fans. A fan switching relay 14 that switches the fan is provided between the heating prevention thermostat 20 and the defrost heater 21. In FIG. 1, at the time of defrosting, a timer (not shown) applies power to the defrosting heater circuit to energize the defrosting heater 21 and the fan switching relay, so that the inner fan 12 changes from low speed rotation to high speed rotation, and the outer fan 13 rotates forward. Switch from rotation to reverse rotation. The flow of air at this time is indicated by an arrow. Simultaneously with the start of defrosting, the outer fan 13 rotates in the reverse direction and warm air is sucked in through the air outlet 8a and the outer air passage 8
Is reversely flown in the direction of arrow C and is blown out from the suction port 8b. In this case, almost all of the warm air blown out from the suction port 8b is sucked into the inner ventilation passage 7 as indicated by the arrow D by the fan 12 which is rotated at a high speed, and is made to flow in the direction of the arrow A, so that the defrost heater 21 Heated by, cooler 1
The defrost generated in No. 1 is removed. Then, the air is blown from the air outlet 7a to form the air curtain 15, and a part of the air flows to the air outlet 8a. Next, when the temperature of the air blown from the cooler or the temperature of the entire cooler is T ₆ (close to 0 ° C), that is, when the frost generated in the cooler becomes water at 0 ° C, the overheat prevention thermostat 20 operates to operate the defrost heater. The inner fan is switched from high speed to low speed, and the outer fan is switched from reverse rotation to forward rotation with no power supplied. Then, a few minutes after the water in the cooler has completely flowed, the temperature thermostat operates, the defrosting ends, and the cooling operation starts. Needless to say, during the cooling operation, the commodities in the display room 5 are cooled by circulating in the directions of arrows A and B shown in FIG.

〔The invention's effect〕

As described above, in the present invention, as compared with the conventional defrosting method using only the defrosting heater, a large amount of outside air having high energy at high temperature is introduced into the cooler section, and yet, the heating is performed by the defrosting heater with higher energy. Therefore, the defrosting time is greatly shortened. In addition, after changing the state of the 0 ° C frost ice generated in the cooler to 0 ° C water with the above-mentioned high energy in a short time, energization of the defrost heater, high speed rotation of the internal fan and reverse rotation of the external fan are performed. By stopping the introduction of outside air by rotation with the heating preventer, air with high energy does not flow through the cooler, and as shown in Fig. 2, the temperature difference between the upper and lower parts of the cooler gradually disappears. It becomes uniform at the temperature T ₂ at the end of frost. Therefore, during the next cooling operation, the cooling energy corresponding to the temperature difference T ₃ -T ₂ between the upper and lower parts of the cooler shown in the conventional example is effectively used to lower the product temperature, and the product temperature rapidly increases to the proper temperature. Go down. Also, compared to the conventional example, the temperature rise of the product during defrosting is reduced because the defrosting method changes to a low energy defrosting method during defrosting, and the product is warmed by defrosting air during defrosting. Since the influence of the product is small, it is possible to keep the temperature rise of the product to a minimum, the product is not damaged or discolored, and the freshness can be maintained for a long time.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention,
FIG. 1 is a cross-sectional view of a showcase showing the flow of air at the start of defrosting, and FIG. 2 is an explanatory view showing its temperature change characteristic.
FIG. 3 is a wiring diagram of the defrosting heater circuit, FIG. 4 is a cross-sectional view of a showcase showing a flow of air at the time of defrosting in a conventional example, and FIG. 5 is an explanatory diagram showing its temperature change characteristic. 1 ... Main body case, 2 ... Outer box, 3 ... Inner box, 4 ... Shelf plate, 5 ... Display room, 6 ... Partition wall, 7 ... Inner ventilation passage, 7
a ... Blowout port, 7b ... Suction port, 8 ... Outside ventilation passage, 9
... Air rectifier, 11 ... cooler, 12 ... fan, 1
3 ... Fan, 14 ... Relay, 15 ... Inner air curtain, 16 ... Outer air curtain, 20 ... Heating prevention thermostat, 21 ... Defrost heater.

Claims (1)

[Claims] 1. An inner ventilation passage containing a cooler and a fan and an outer ventilation passage containing a fan are provided between an outer box and an inner box of a main body case having an opening on the front surface or the upper surface, and the outer ventilation path has a built-in fan. In the cold air circulation type open showcase configured to form a multi-layered air curtain in the opening by each fan, at the start of defrosting operation, the fan of the outside ventilation passage is reversely rotated and the defrosting heater is energized, The outside air introduced by backflowing through the outside ventilation passage is sucked into the inside ventilation passage by rotating the fan in the inside ventilation passage at a speed higher than the low speed rotation during cooling operation to defrost the cooler and perform defrosting operation. At some time, when the cooler outlet air temperature reaches a predetermined temperature lower than the defrosting end temperature, the fan in the outer ventilation passage is rotated forward and the defrosting heater is de-energized, and the inner ventilation passage is stopped. Defrosting method refrigerated open showcase, characterized in that the driving switching the fan on low speed at the time of cooling operation.