JPS61213568A - Method of controlling operation of refrigerator - 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] [Technical field to which the invention pertains]

ν /'ISH＆ νMedium temperature SI IJ Reno −
hII r elm ^ Buddha 1 torture vending machine to keep this stored items cold. This invention relates to an operation control method for defrosting a refrigerator used by being incorporated into a refrigerator showcase or the like.

[Prior art and its problems]

First, let's take the above-mentioned vending machine for selling frozen products such as ice cream as an example.
This will be explained using a diagram. In Fig. 3, l is the compressor of the refrigerator, 2 is the defrosting heater installed in the cooler, 3 is the thermostat for regulating the temperature inside the refrigerator, and 4 is the operating mode that switches between cold preservation operation and defrosting. This is a defrost control timer. The operation control circuit of such a refrigerator is well known; during cold storage operation, the timer contact is on the "cooling" side, and the compressor l is controlled on and off by the operation of the thermostat 3 to keep the temperature of the products stored in the refrigerator almost constant. Operation is controlled to maintain the temperature. It is turned on by this thermostat. The off-control operation mode is defined as thermocycle operation. On the other hand, the above-mentioned timer 4 has a defrosting cycle set in advance at a predetermined time period of once or several times a day. The timer contact switches from "cooling" to "defrosting".
The refrigerator shifts from cold storage operation to defrosting operation mode. When defrosting begins, the compressor 1 is stopped, and at the same time, the defrosting heater 2 is energized, and the heater forcibly heats the cooler to defrost the frost that has adhered to the cooler during the cold storage operation. In this case, the timing of the end of defrosting is set in advance by the timer 2, or is controlled so that the defrosting operation is forcibly switched back to the cold storage operation by the operation of a defrosting end thermostat (not shown). However, in the conventional operation control method described above, the following problems occur because the defrosting cycle and the compressor on/off control by thermocycle operation are not synchronized in time and proceed completely separately. In other words, FIG. 4 shows a time chart of the operation based on the operation control circuit of FIG. 3. During cold storage operation, the compressor is controlled to operate and stop in response to the on/off operation of the thermostat. As a result, the temperature of the frozen product in the refrigerator is maintained at a substantially constant temperature, for example, within the range of -18 to -20° C. and within the product temperature fluctuation range Ta -2 degrees. On the other hand, when a predetermined period of time has elapsed and the cold preservation operation is switched to defrosting under timer control, the compressor is stopped during this defrosting period and electricity is supplied to the defrosting heater. In this case, if the cold storage operation is switched to defrosting at time t1 when the compressor 1 is stopped during thermocycle operation as shown in the figure, then at time t2 when the compressor was stopped during the previous thermocycle operation. Continuously from time t2 until time t3 when defrosting ends including the time from

The compressor continues to stop until [3], and during this period, no cooling is performed and heat is added to the compressor as well as defrosting heat. As a result, the temperature of the frozen products stored in the refrigerator rises, reaching 115 degrees Celsius just before the end of defrosting. In this example, the temperature rise width Tb due to defrosting is the product temperature during cold storage - 2
It is 5 degrees based on 0°C. By the way, in general, the appropriate temperature for eating frozen foods such as ice cream is determined. For example, for ice cream, the optimal temperature is around -20℃, and if the temperature rises to about -15℃, In addition to becoming soft and having a bad texture, those with a high milk content also deteriorate in quality, including a decrease in flavor. For this reason, it is important to maintain this appropriate product temperature even when storing ice cream in a vending machine and storing it frozen, in order to provide customers with high-quality products. Moreover, the degree of quality deterioration in the case of storage is more affected by the rise in the absolute temperature of the product than by the fluctuation range of the storage temperature.For this reason, it is difficult to store frozen products such as ice cream in the refrigerator. In the case of frozen storage, an extremely important point in maintaining quality is how to keep the absolute temperature rise of the product low throughout the entire period, including cold operation of the refrigerator and defrosting. [Purpose of the Invention] This invention was made in view of the above points, and maintains the quality of frozen products such as ice cream by suppressing the rise in product temperature due to defrosting, which is a drawback of conventional operation control methods. The purpose of the present invention is to provide an operation control method for a refrigerator that enables the following.

[Key points of the invention]

In order to achieve the above object, the present invention controls the operation by switching the compressor operation mode from thermocycle operation under thermostat control to forced continuous operation for a predetermined period of time before the start of defrosting in the process of transitioning from cold storage operation to defrosting. By doing so, before starting defrosting, the products stored in the refrigerator are always cooled down sufficiently regardless of the progress of thermocycle operation, and by defrosting from this state, the products that will be defrosted will be removed. This is intended to reduce the absolute temperature rise.

[Embodiments of the Invention] Fig. 1 shows a refrigerating machine operation control circuit according to the present invention, Fig. 2 shows a time chart of the operation operation by the circuit shown in Fig. 1, and the same parts as Fig. 3 are shown. The sign is attached. In other words, the defrost timer 4 is equipped with a timer contact for setting three operating modes: "cooling", "defrosting", and "forced cooling", and the timer contact for "forced cooling" is directly connected to the compressor 1. It is connected to the. The "forced cooling" operation mode is set so that forced cooling is performed for a predetermined period of time, for example, about one hour, before the start of defrosting, based on the time of starting defrosting. Next, the operation control operation by the above circuit will be explained with reference to FIG. That is, during the cold storage operation, the thermocycle operation is performed in the same manner as shown in FIG. 4, except for a specific time period before switching to defrosting. And the preset defrosting start time t1
When approaching , the timer contact switches from "cooling" to "forced cooling" at time t4, which is a time to before the defrosting start time t1, and the operation mode changes from thermocycle operation to forced continuous operation. Furthermore, from this point on, time t. When the time has elapsed, the timer contact switches to "defrost" and defrost begins. Through this series of control operations, the temperature of the products stored in the refrigerator reaches a minimum temperature of 9, for example, - at the stage just before the start of defrosting.
The temperature will drop to 22 degrees Celsius. This temperature is a value lower by the temperature range Tc than the lowest cold storage temperature during thermocycle operation. Therefore, with the subsequent defrosting, the product temperature will change to the same temperature range (5d
eg) Even if the temperature increases, the absolute value of the temperature increase is at most -
The temperature remains at 17°C, and the temperature rise during defrosting in Figure 4 is -1.
The temperature can be maintained at a temperature lower than 5° C., and this makes it possible to always sell high-quality ice cream. Although the above was described using an ice cream vending machine as an example, the same effect can be achieved even if it is applied to a vending machine for frozen products other than ice cream or a showcase that handles frozen products. can.

【Effect of the invention】

As described above, according to the present invention, in the process of transitioning from cold preservation operation to defrosting, the operation mode of the compressor is switched from thermostat-controlled thermocycle operation to forced continuous operation for a predetermined period of time before the start of defrosting, and the operation is controlled. By doing so, the products stored in the refrigerator are not affected by heat leakage while the compressor is stopped due to thermocycle operation, and are continuously forcedly cooled to a sufficiently low temperature before the start of defrosting. Therefore, the absolute temperature increase due to defrosting can be kept lower than that of conventional methods, and this allows the products stored in the warehouse to be kept at the appropriate temperature throughout the entire period, including cold storage operation and defrosting, and to ensure quality. can be achieved.

[Brief explanation of drawings]

FIG. 1 and FIG. 3 are respectively diagrams of the operation control circuit of a refrigerator according to an embodiment of the present invention and a conventional one, and FIGS. 2 and 4 are diagrams of the control operation of the refrigerator using the circuits of FIG. This is a time chart. In the figure, l: compressor, 2: defrost heater, 3: thermostat, 4
: Defrost timer. Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1) During cold storage operation, a thermocycle operation is performed in which the compressor is controlled on and off by thermostat control to maintain the stored items at a substantially constant temperature, and the cold storage operation is stopped at a predetermined cycle. In a refrigerator operation control method that switches to defrost mode and forcibly heats the cooler to defrost during this defrost period,
A refrigerating machine operation control method characterized in that in the process of transitioning from cold preservation operation to defrosting, the operation mode of the compressor is switched from the above-mentioned thermocycle operation to forced continuous operation for a predetermined period of time before the start of defrosting. . 2) An operation control method for a refrigerator according to claim 1, characterized in that the operation modes of thermocycle operation, defrosting, and forced continuous operation are switched by timer control.