JPH01310278A - Cooling operation of freezing refrigerator - Google Patents

Abstract

PURPOSE:To permit sufficient cooling after defrosting as well as the quick cooling of stored matters, whose temperature is risen upon the defrosting, to an objective temperature by a method wherein the title freezing refrigerator is operated after the defrosting at the lower limit of a corrected set temperature set at a lower setting temperature in accordance with the increasing width of a temperature in the refrigerator upon defrosting. CONSTITUTION:In a front surface opening type open cold storage showcase 1, the chambers of an open space 7 are intercepted from atmosphere by inner and outer double air curtains 8, 9. After defrosting, a lower limit temperature is set at a lower temperature in accordance with the increasing width of a temperature in the showcase upon defrosting to effect cooling operation control based on the newly corrected set temperature and prevent the delay of cooling of stored matters due to thermocycle operation started before arriving at the objective values of a temperature in the showcase and the temperature of stored matters when the operation is controlled based on a lower limit value of temperature before changing the set temperature. The lower limit value of the corrected set temperature is changed so as to be returned to the initial set temperature gradually and the continuation of cooling operation is decided by comparing the lower limit value with the temperature of circulating air and when the temperature of the circulating air has become higher than the initial lower limit value or the same temperature does not become higher than the lower limit value for a given period of time, the operation is controlled by a normal lower limit value after that time.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a freezing/refrigerating showcase that cools the inside of a refrigerator by an air circulation method, or a cooling operation system for a freezing/refrigerator.

(b) Conventional technology For example, air circulation type refrigeration, which cools the inside of the refrigerator with an air curtain of cold air that is formed inside the refrigerator by forcibly circulating cooling air, or cold source showcases and freezers/refrigerators. The structure is roughly as shown in FIG. That is, inside the showcase body 1, circulation fans 4 and 5 are arranged in double internal and external cold air circulation paths 2 and 3. Road 2
The cool air that has undergone heat exchange in the cooler 6 is circulated inside the warehouse to form a double cold air curtain 8.9 inside and outside the front lower part of the showcase main body 1, thereby separating the outside air and the warehouse. The inside of the refrigerator is shut off and cooled.

By the way, in order to keep the temperature inside the refrigerator almost constant at a predetermined level,
Thermocycle operation control is widely practiced in which the cooler 6 is operated at the upper limit of a preset reference temperature and stopped at the lower limit. In this case, there is a differential of several degrees between the upper limit and lower limit of the set temperature, and this differential does not change even if the set temperature is changed. Generally, this control targets the temperature of the circulating air in the refrigerator.For example, the temperature of the discharged air of the circulating air is measured and compared with predetermined upper and lower limits to turn on the cooler.
, discharge air temperature control that turns it off.

Similarly, operation control methods such as suction air temperature control or calculated warehouse temperature control calculated based on discharge and suction air temperatures are performed. A temperature controller such as a thermostat is used to control these temperatures, and the temperature measuring unit 10 of the temperature controller is installed near the circulating air outlet 11, for example.
The temperature of this discharged air is detected, and when the temperature exceeds the upper limit of the set temperature, the compressor is driven to perform cooling, and when the temperature reaches the lower limit of the set temperature, the compressor operation is stopped. The temperature inside the refrigerator is controlled by this method.

Furthermore, when there are multiple freezers, refrigerators, etc. to be controlled, the start and stop of supply of liquid refrigerant to the evaporator (cooler) in the refrigerant circuit is controlled by a liquid solenoid valve or the like.

With such a control method, the inside of the refrigerator is cooled by circulating air, but as the refrigerator 6 cools, frost forms on the cooler 6 and the cooling capacity decreases, so defrosting is required.

Defrosting is carried out using an appropriate method such as a heater or hot gas.
After defrosting, turn on the cooling operation again based on the temperature of the circulating air inside the refrigerator.
, OFF control, that is, thermocycle operation is performed to control the temperature inside the refrigerator.

(c) Problems to be solved by the invention However, during defrosting, the operation of the cooler is stopped and only forced circulation air is created by the circulation fan.
The temperature inside the warehouse and of stored items also rises. And after defrosting,
The operation of the cooler is restarted and the elevated interior of the warehouse and the stored items are cooled again by the air curtain using circulating air. At this time, the temperature of the air curtain caused by the circulating air decreases in a relatively short period of time and circulates, but the temperature inside the refrigerator and the stored items has not yet decreased sufficiently. However, since cooling control is performed based on the temperature of this circulating air, the cooling system is turned on and off when the temperature inside the warehouse and stored items does not reach the target temperature.
Since FF cycle operation is performed, it takes a long time to reach a stable predetermined temperature state, and cooling of the stored items is delayed, resulting in a decrease in quality.

I think the above-mentioned pattern of temperature changes can be better understood from the graph in Figure 3. In other words, FIG. 3 shows the inner layer discharge air temperature A1, inner layer suction air temperature Bl, chamber interior temperature CI, and storage temperature of the showcase, which maintains the refrigerator internal temperature constant by controlling the inner layer discharge air shown in the structure of FIG. 1. The graph shows changes in the product temperature D1. In the figure, each temperature increases with defrosting. The temperature drop in the internal temperature CI and the product temperature D1 after defrosting is slower than the drop in the inner layer discharge air temperature A1, so if the thermocycle operation is controlled at the same lower limit value as before defrosting, the internal temperature CI and the product temperature will decrease. Thermocycle operation is performed before D1 reaches the target temperature. For this reason, it takes a long time of 60 minutes until cooling becomes stable.

In addition, as shown in Japanese Utility Model Publication No. 58-3029, in a cooling system that uses a timer to alternately repeat on and off times of the cooling device, that is, duty cycle operation, after defrosting is completed, the temperature inside the refrigerator is It has been proposed that during pull-down operation until the lower limit is reached, the duty cycle is stopped and a temperature controller is used to turn on and off the cooling operation, but the purpose of the temperature controller in this case is , the time to start the due-day cycle operation is when the temperature reaches a predetermined low temperature detected by this temperature controller, and since this predetermined low temperature is the internal temperature, the actual product temperature is still not the same. Since the temperature has not yet been reached and the duty cycle operation starts at such a time, a cooling delay of the stored items also occurs.

The present invention completely eliminates the drawbacks caused by the above-mentioned prior art,
An object of the present invention is to provide a cooling operation system for a freezer/cold storage that can resolve the delay in cooling stored items by quickly cooling the temperature of stored items that has risen during defrosting to a target temperature.

(d) Means for Solving the Problems The cooling operation method for freezers and refrigerators according to the present invention controls the ON/OFF cycle operation of the cooling device based on the temperature of the circulating air inside the refrigerator, that is, the reference set temperature. Set in advance,
At the upper limit of this set temperature, the compressor or liquid solenoid valve is turned on to start supplying liquid refrigerant to the evaporator (cooler), and at the lower limit, the compressor or liquid solenoid valve is turned off and liquid is supplied to the evaporator. In a system that controls the temperature inside the refrigerator by interrupting the refrigerant supply, after defrosting, the lower limit temperature is set lower according to the rise in temperature inside the refrigerator during defrosting, and a new Delay in cooling of stored items due to thermocycle operation that starts before the internal temperature and product temperature reach the target temperature, which occurs when cooling operation is controlled based on the corrected set temperature and controlled at the lower limit value before the setting change. In addition, the lower limit value of the corrected set temperature is changed so as to return to the gradual dimension, and the lower limit value is compared with the temperature of the circulating air to determine whether to continue the cooling operation, and after the lower limit value is equal to or higher than the original lower limit value, or If the lower limit value is not exceeded within a certain period of time, control is performed at the normal lower limit value from that point on.

(E) Function Since the lower limit of the set temperature that determines the thermocycle operation of the cooling device after defrosting is lowered, the interior of the refrigerator can be rapidly cooled, and the time when the desired interior temperature is reached. You can return to normal control.

(f) Example The present invention will be explained in detail below.

In an open-front refrigerated showcase 1 as shown in FIG. 1, an open section 7 is separated from the outside air and the inside of the refrigerator by double air curtains 8 and 9, both inside and outside. Here, the start and stop of liquid refrigerant supply to the cooler 6 is controlled by starting and stopping the compressor and opening and closing the liquid solenoid valve, and the temperature inside the refrigerator is kept constant by controlling the temperature of the inner layer discharge air 8. is maintained. That is, the inner layer discharge air temperature is controlled to be between the upper and lower limits of the set temperature, which is a preset control reference value, and the operation of the cooling device is controlled to maintain it within this temperature range. . Here, the lower limit temperature value after defrosting is calculated using the following equation, and after defrosting, the internal operation control is performed using the calculated value as the new lower limit value.

Sd = So −k (K□−, )+D−T
...(1) Sd: Lower limit value after defrosting ("C) So: Normal lower limit value (℃) k: A coefficient determined by the degree to which the rise in internal temperature during defrosting affects the product temperature. : 0 to the internal temperature after defrosting ('C) or the calculated internal temperature after defrosting: 0 to the internal temperature before defrosting (℃) or the calculated internal temperature before defrosting 0: Removed Internal temperature rise due to frost ('C) D: When cooling at the lower limit after defrosting, the discharge setting increase rate ('C/min) determined by the degree of influence on product temperature T: After defrosting Elapsed time (minutes) The lower limit value Sd after defrosting shown by the above formula (1) gradually decreases with the elapsed time after defrosting.Then, the lower limit value Sd that changes from moment to moment and the discharge air temperature A2 at each point in time, and if the discharge air temperature A2 is higher than the lower limit value Sd, the cooling operation is continued, and A2=Sd.
Cooling operation will be stopped when this happens. After that, the lower limit S
Thermocycle operation is started with the upper limit value being the temperature value of d plus a constant temperature.

Then, the return to the thermocycle operation based on the normal lower limit value So is performed based on the judgment result of the following two conditions, and until then, a lower limit value setting change section of the thermocycle is formed.

By the way, the conditions for this determination are: (1) After Sd≧So, control is performed using the normal lower limit value SO.

(2) If (1) is performed and the system does not recover within the certain period of time (1), then control is performed using the normal lower limit value So. That is what it is.

As described above, the calculation of the series of lower limit values Sd, the comparison with the discharge air temperature A1, and the comparison judgment with the normal lower limit value SO can be performed under control by a microprocessor. here,
For example, 5o=-5°C, k=0.5. Ko = -3°C.

Assuming that K = 5°C and D = 0.125°C/min.

Sd = =3℃-0,5(5-(-3))℃+0.1
25°C/min x T = -7°C + 0.125°C/min XT
...(2).

FIG. 2 shows the temperature when the lower limit temperature after defrosting is changed based on this equation (2). As understood from the figure, inner layer discharge air temperature A2, inner layer suction air temperature B2,
The temperature inside the refrigerator C3 and the product temperature D2 decrease quickly, and it takes 40 minutes for the inside of the refrigerator to reach the target temperature of -3°C.
The conventional control method shown in FIG. 3, in which the set values do not change, takes 60 minutes, but this time can be significantly shortened, which is a significant improvement.

In addition, when controlling the temperature using the upper limit value, the upper limit temperature value after defrosting is calculated using the following formula, and after defrosting, the internal operation control is performed using the calculated value as the new upper limit value.

5d=So-kCK,-X,)+D4
(1) Sd: Upper limit value after defrosting ('C) So: Normal upper limit value ('C) k: A coefficient determined by the degree to which the rise in internal temperature during defrosting affects the product temperature: To the internal temperature after defrosting (℃) or the calculated internal temperature after defrosting.: According to the internal temperature before defrosting ('C) or the calculated internal temperature before defrosting -Ko: By defrosting Temperature rise inside the refrigerator (°C) D: When cooling at the upper limit after defrosting, the rate of increase in discharge setting (°C/min) determined by the degree to which it is affected by product temperature T: Elapsed time after defrosting ( (min) When the band of the upper limit value and the lower limit value is not changed, D and K in the above formula have the same value, and when the band is changed, D and K have different values.

(G) Effects of the Invention The operating method of the present invention, in the ON/OFF cycle operation control of the cooling device, sets the lower limit of the preset temperature that is the condition for the OFF operation after defrosting. Since operation is now performed at the lower limit of the corrected set temperature, which is set lower according to the range of temperature rise inside the warehouse, sufficient cooling is performed during defrosting, and the temperature of stored items that rose during defrosting can be quickly adjusted to the target value. It is possible to cool down to temperature.

Therefore, for example, when fresh foods are stored, a decrease in freshness due to a temperature rise during defrosting can be minimized. Further, when the temperature inside the refrigerator reaches the target temperature, the thermocycle control is started based on the first lower limit value, and normal operation cannot be resumed automatically.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a front-opening open showcase, which is a type of freezer/refrigerator, Figure 2 is a graph showing the temperature of the contents of the showcase under this operating method, and Figure 3 is the temperature of the contents of the showcase under the conventional operation method. FIG. 1... Showcase body, 2, 3... Cold air circulation path,
6... Cooler, 10... Temperature measuring part of temperature controller, Al
, A2... Inner layer discharge air temperature, Bl, B2... Inner layer suction air temperature, CI. C2... Inner temperature, Di, D2... Product temperature. Figure 1 Procedural Amendment (Master) August 29, 1986

Claims (1)

[Claims] The temperature of the circulating air inside the refrigerator is detected, and when the temperature reaches the lower limit of the set temperature, which is a preset reference, the operation of the cooling system is stopped, and when the temperature reaches the upper limit of the set temperature, the operation of the cooling system is restarted. In a cooling operation method for freezers and refrigerators that perform cycle operation to keep the inside of the refrigerator at a predetermined temperature, after defrosting is completed, the lower limit value is set lower according to the range of temperature rise inside the refrigerator during defrosting. Drive the cooling device at the set temperature,
After driving, operation control is performed based on a set value that gradually returns to the lower limit value of the dimension, and after returning to the lower limit value, or if it does not return within a certain period of time, normal cycle operation is performed from that point onwards. Cooling operation method for freezers and refrigerators.