JPH0221177A - Defrosting system for chilled-air circulation type open showcase - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a defrosting method for a multilayer air curtain type cold air circulation type oven showcase.

[Conventional technology]

First, as a multilayer air curtain cold air circulation open showcase to which the present invention is applied, the structure of a conventional three-layer air curtain open showcase will be described with reference to FIG.

In the figure, ■ is an open front case body, 23 is an outer box and an inner box of the case body 1, and an inner layer duct 4. There are three inner and outer layers of circulating air ducts defined by the middle layer duct 5 and the outer layer duct 6. In the illustrated example, the bottoms and rear regions of the middle layer duct 4 and the outer layer duct 5 are defined side by side in the longitudinal direction of the case body 1, and appear to overlap in the drawing. Further, the ducts 4, 5.6 of each layer have an inner layer fan 7, a middle layer fan 8. An outer layer fan 9 is provided, and the inner layer duct 4 is further provided with a cooler lO placed in the rising portion of the duct at the rear of the inner box and a defrosting heater 11 placed on the inlet side of the cooler lO. In addition, 12
13 is a product display fence inside the warehouse, and 13 is a drain hole for draining defrosting water provided at the bottom of the case body l.

With this configuration, each layer fan 7°8.9 and cooler 10 are operated during cold preservation operation. As a result, each layer duct) 4,
5.6, air is circulated as shown by the solid line arrow in the figure, and three layers of air curtains A and B are formed inside and outside the front opening of the case body 1.
, C are formed by blowing. Of these, inner layer air curtain A
is a cold air curtain cooled by heat exchange with the cooler 10, middle layer 1 outer layer air curtain B and C are cold air curtain A
This is a protective air curtain that shields the space between the refrigerator and the outside air, and in this state, products such as fresh foods (not shown) displayed in the display 1112 inside the refrigerator are kept cool.

On the other hand, cooling during cold storage operation! Defrosting control J for removing frost adhering to 110 is performed using a time start/temperature return method at -m. That is, when the operation mode is switched from cold storage to defrost by timer control in a predetermined time cycle, the cooler 10 is stopped while the fans 7, 8, and 9 of each layer continue to operate, and the defrost heater 11 is energized. Defrost heater 1
The air heated in step 1 is blown into a cooler 10 to melt and remove frost. When the defrosting operation is finished and the temperature on the outlet side of the cooler 10 rises to a preset temperature, a defrosting end thermostat (located on the outlet side of the cooler 10) that detects this temperature and operates. The defrosting heater 11 is stopped in response to a signal of 1), and the cooler 10 is restarted and switched to cold storage. Further, the defrosting water generated by defrosting flows down the surface of the cooler 10 and drips downward, and from there flows into the drain hole 13 and is drained out of the case.

In addition, FIG. 3 is an operation time chart of cold storage and defrosting using the conventional defrosting method described above, and FIG. 4 is a cold storage.

It is a temperature characteristic diagram showing the temperature of the product and the temperature Ftk of the cooler due to defrosting, Hl indicates the defrosting start time, H2 indicates the defrosting end time, and in Fig. 4, (a) The product temperatures (b) and (c) are the temperatures at the inlet and outlet sides of the cooler 10, respectively, and T1. T4 represents the cooling temperature of the cooler and the product, respectively.

[Problem to be solved by the invention]

By the way, in the conventional heater defrosting method described above, the temperature of the product rises widely due to defrosting (and it takes a long time for the product temperature to drop to the appropriate cold storage temperature after resuming cold storage). There is a problem with products such as fresh food being easily perishable.

Next, to explain this with FIG. 4, during defrosting, air heated by the defrosting heater 11 is sent into the cooler 10 from the inlet side, so the inlet side temperature (b) is higher than the outlet side temperature (c). becomes higher. Therefore, at the end of defrosting H2, the temperature on the outlet side of the cooler is 72 (corresponding to the set temperature of the defrosting end thermostat), but the temperature on the inlet side rises to a higher temperature T3, and both A large temperature difference between
T3-T2) occurs. For this reason, when the operating mode of the case is switched from defrosting to cold storage, it takes a considerably long time (+13) for the temperature of the entire cooler to drop to the predetermined cold storage temperature TI. .

On the other hand, the temperature of the products displayed in the warehouse shows a lag characteristic with respect to the temperature characteristic of the cooler described above. The temperature will gradually rise, but since the temperature of the cooler does not drop rapidly even after defrosting and the circulating air in the refrigerator maintains a high temperature at this point, the temperature will rise for a while even after cooling is resumed. The temperature continues to increase to T5, then decreases, and then settles at the cold storage temperature T1. Moreover, as mentioned above, it takes a long time for the temperature of the cooler to drop after resuming cold storage, so the product temperature rise T5 is correspondingly higher, and the time H4 until the temperature returns to the appropriate cold storage temperature T4 is also longer. Become. As a result, the freshness of products such as fresh foods decreases, causing problems such as accelerated deterioration of quality.

Furthermore, in the arrangement of the cooler 10 shown in FIG. 5, the flow of air through the inner layer duct 4 is opposite to the direction of dripping of the defrosting water melted by defrosting and the direction of drainage to the drain hole 13. can be,
These work to prevent water draining, and for this reason, the dripping and drainage of defrost water from the cooler is incomplete, and when the transition from defrosting to cold preservation occurs, the defrost water turns into ice again and grows, causing Ice blocks called ice banks form and block ventilation.

The present invention has been developed in view of the above points, and has the advantage of shortening the temperature drop time of the cooler when transitioning from the end of defrosting to cold storage, thereby minimizing the rise in product temperature caused by defrosting, and at the same time To provide a defrosting method for a cold air circulation type oven showcase that facilitates draining of defrosting water and also obtains an AT drop.

(Means for Solving the Problems) In order to solve the above problems, the defrosting method of the present invention uses a forward-reverse fan as the inner layer fan disposed in the inner layer duct, stops the cooler during defrosting, and In the first half of the period, the defrosting heater is energized to defrost the heater, and in the second half, the defrosting heater is stopped and the inner layer fan is reversed to perform air defrosting.

[Function] In the above, when switching from cold storage to defrosting, the defrosting heater is first energized to start defrosting. As a result, the heat from the heater melts the frost adhering to the cooler, similar to the conventional method. When the temperature of the cooler rises to around o'c (melting temperature of *), the defrost heater is de-energized based on the operation signal of the thermostat, and the inner fan is switched to reverse rotation.

As a result, the ventilation direction of the inner layer duct is reversed, and the air in the inner layer duct, whose temperature has been increased by the heater heating, makes a U-turn and provides defrosting heat to the cooler.

Furthermore, at the front opening of the case body, air from the inner layer duct blows out from below, causing turbulence in the air curtain. Air with a high amount of heat is sucked into the inner layer duct from the duct side, flows in the opposite direction to when defrosting the heater, and flows through the cooler. As a result, defrosting further progresses, and at the same time, the defrosting water melted by the heater defrosting also progresses, and the temperature of the entire cooler is equalized by the defrosting air flow. When the cooler temperature reaches a predetermined temperature, the operation signal from the defrosting end thermostat switches from defrosting to cold preservation, and the inner fan returns to normal rotation, and the cooler resumes operation.

Moreover, as mentioned above, the power supply to the defrosting heater is interrupted during the first half of the defrosting period, and at the end of the defrosting period, there is almost no temperature difference between the inlet and outlet sides of the cooler due to the reverse ventilation in the latter half. It's gone. Therefore, after resuming cold storage operation, the cooler will drop to the cold storage temperature within a short time. In addition, the earlier the power supply to the defrosting heater is stopped, the less influence it has on the rise in product temperature, and the time it takes for the product to return to an appropriate cold storage temperature is quicker. Furthermore, power consumption is reduced by the shorter energization time of the defrosting heater, and in the cooler arrangement shown in Figure 5, the reversal of the inner layer fan allows the direction of ventilation in the inner layer duct and the defrosting water droplets from the cooler to be reduced. Since the flow of the drainage water is in the same direction as the bottom, the flow of the defrosting water is facilitated by the flow of air.

[Example] Fig. 1 shows an operation time chart for cold storage and defrosting by the defrosting method of the present invention, and Fig. 2 shows a temperature characteristic chart of product temperature and cooler during defrosting.

In addition, the defrosting start and end times 81. shown in the figure. H2,
Cooler, product cold storage temperature H, T4, defrost end temperature ↑2,
The temperature characteristic lines (43 ports, ) 1) in FIG. 2 correspond to FIGS. 3 and 4.

That is, according to the present invention, a forward/reverse rotation fan is installed as the inner layer fan 7 shown in FIG. Further, as shown in Fig. 1, when the timer control switches from cold preservation to defrost at time H1, the operation of the cooler 10 is stopped by a command from a controller (not shown), and the operation of the cooler 10 is stopped while the inner fan 7 is kept in normal rotation. The frost heater 11 is energized to start heater defrosting. Then, when the temperature at the outlet side of the cooler 10 rises to T5 (0'C) and the frost begins to melt, a (time 85) is reached.
The power supply to the defrosting heater 11 is stopped by the operation signal of the thermostat, and the inner layer fan 7 is switched to reverse rotation.

As a result, the ventilation condition in the inner layer duct 4 changes as shown by the dotted arrow in FIG. That is, in the inner layer duct 4, the air that has been ventilated in the direction of the solid arrow makes a U-turn, and the air flows from the outlet side (upper part) to the inlet side (upper part) of the cooler 10.
In this process, the air inside the duct, which has been heated and heated by the defrosting heater 11, flows through the cooler 10 again and provides defrosting heat. Furthermore, at the front opening of the case body 1, the air blown upward from the cold air intake port (lower part) of the inner layer duct 4 disturbs the air curtain that had been forming a laminar flow, and as a result, the air flows from the middle layer duct 5 side. Air with high retained heat is sucked into the inner layer duct 4 and flows to the cooler 10, where so-called air defrosting is performed. Moreover, by this reverse ventilation, the temperature is equalized so that the difference between the temperature at the inlet side and the temperature at the outlet side of the cooler 10, which is generated during the process of defrosting the heater, is minimized.

Moreover, the flow direction of the defrosting water dripping from the surface of the cooler 10 and flowing into the drain hole 13 matches the ventilation direction in the inner layer duct 4 shown by the dotted line, so that the drainage of the defrosting water is facilitated by the air blowing. be completed promptly.

On the other hand, when the temperature of the cooler [O] rises to the temperature T2 set by the defrosting end thermostat, the defrosting ends at this point H2 and the cooling mode returns. Furthermore, at the time of resumption of cooling, there is no temperature difference (T3-↑2) between the inlet and outlet sides of the cooler 10 as shown in FIG. 4, and the temperature difference is reduced by 21! The capacity works effectively and the temperature of the cooler 10 decreases more quickly. As a result, the time H6 required for the temperature to drop to the cold storage temperature T1 is significantly shorter than the time H4 in FIG. 4. Furthermore, due to the synergistic effect of the temperature characteristics of the cooler 10 described above and the de-energization of the defrosting heater 11,
Naturally, the product temperature characteristics, that is, the product temperature T6 that rises with defrosting, the product temperature T5 in Figure 4 also becomes small, and the time H7 required for the product temperature to return to the appropriate cold storage temperature T4. The time is also significantly shorter than the time H4 in FIG. Furthermore, the amount of power consumed during defrosting is also reduced by the amount of time the defrosting heater 11 is energized.

〔Effect of the invention〕

The defrosting method of the present invention described above provides the following effects.

In other words, the inner layer fan arranged in the inner layer duct is a forward-reverse fan, and the cooler is stopped during defrosting, and in the first half of the defrosting period, the defrosting heater is energized to defrost the heater.
In the second half, the defrost heater was stopped and the inner fan was reversed to defrost the air and defrost proceeded. Temperature drop can be accelerated.

(2) By shortening the defrosting time and synergistic effect with the previous item, the rise in product temperature due to defrosting can be suppressed to a small extent.
Moreover, the temperature of the product will drop faster after the cold storage is resumed, making it fresh! ! 1. It is possible to maintain the quality of products such as foods.

(3) Due to the reverse transfer wind in the latter half of the defrosting period, the defrosting water is
Since drainage proceeds smoothly and quickly, it is possible to prevent the defrosting water from refreezing and forming ice banks when cooling is resumed.

(4) Power consumption can be reduced by shortening the energization time of the defrosting heater.

Practical effects such as these can be obtained.

[Brief explanation of the drawing]

Figures 1 and 2 are operation time charts for cold storage and defrosting using the defrosting method of the present invention, and temperature characteristic diagrams showing product temperature and cooler temperature changes, Figures 3 and 4, respectively. 1 and 2 are operation time charts according to the conventional defrosting method corresponding to FIG. 1 and FIG. 2, respectively. and temperature characteristic diagram, Figure 5 is 3I! FIG. 1 is a configuration diagram of a one-piece curtain-type cold air Wi-ring oven showcase. In the figure, 1: case body, 2: outer box, 3: inner box, 4: inner 1 duct, 5: middle layer duct, 6: outer layer duct, 7 inner layer fan, 8
: Middle fan, 9: Outer fan, Figure 1 Figure 3

Claims (1)

[Claims] 1) The front-open case body has multiple layers of internal and external circulation ventilation ducts between the inner box and outer box, and each layer of ducts is equipped with a fan, and the inner layer duct is equipped with a cooler and a defrost heater. This is a defrosting method for cold air circulation type open showcases, in which the inner layer fan placed in the inner layer duct is a forward-reverse fan, the cooler is stopped during defrosting, and the defrost heater is energized during the first half of the defrosting period. In the second half, the defrosting method for cold air circulation open showcases is characterized by stopping the defrosting heater and then rotating the inner fan in reverse.