JPS58138970A - Method of controlling 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 The present invention relates to a method for automatically controlling a refrigeration system for cooling the inside of a refrigerated warehouse.

Conventionally, ON-OFF control using a thermostat has been performed as a means for controlling the temperature of a refrigerated warehouse using a refrigeration device. FIG. 1 shows a system diagram of a conventional refrigeration system, in which the compressor 11. Condenser 12. Expansion valve 13. It consists of an evaporator 14 and refrigerant pipes connecting these, and is controlled by a refrigerated warehouse l.
A temperature detector 16 is provided inside the O, and the signal is sent to the compressor 11 and evaporator 1 by the controller IB through the converter 17.
This is done by turning off the blower 15 of No. 4.

FIG. 2 shows an example of temperature changes within the refrigerated warehouse 10 due to such a method of controlling a refrigeration system. This control stops the operation of the compressor 11 and the blower 15 when the temperature in the refrigerated warehouse reaches the lower limit temperature Tz of the set temperature Ts, and starts operation again when the temperature rises and reaches the upper limit. In this case, if the cooling time becomes longer, frost will build up on the air cooler and the cooling performance will decrease.

The temperature of the air decreases more slowly. Even in such a state, the compressor 11 and the blower 15 are operated because the temperature does not reach the lower limit. However, since the temperature inside the refrigerated warehouse 10 is within the set value range, it is wasteful to continue the operation, resulting in a waste of power.

For this reason, conventional methods have been considered to narrow the upper and lower limits of the set value to eliminate unnecessary cooling;
FF repeat time becomes shorter.

This is not an appropriate control method because it adversely affects the operation of the compressor 11 and blower 15.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control method that eliminates the drawbacks of the conventional control method using an ON-OFF switch and eliminates wasteful power consumption of a refrigeration system.

In cooling a refrigerated warehouse, this invention aims to prevent wasteful operation of the refrigeration equipment when the internal temperature reaches the set range.
using a microcomputer.

The system is configured to predict and judge the temperature change after a predetermined time based on the elapsed temperature change, and control ON/OFF of the operation of the refrigeration system.

FIG. 3 is a system diagram of a method for controlling a refrigeration system according to the present invention;
FIG. 4 is a control flow diagram, FIG. 5 is an example of temperature change in a refrigerated warehouse according to the present invention, and FIG. 6 is another example.

The temperature of the refrigerated warehouse 10 is detected by the temperature detector 16, and is led to the microcomputer 19 via the converter 17 for calculation and comparison with the set temperature.
Or, turn on the blower 15 to 0N-OF'Ft.

Temperature Tz in the refrigerated warehouse measured by the temperature detector 16.

If it is higher than the upper limit temperature T1 of the set temperature T3, the refrigeration equipment continues to operate, and if it is also lower, the temperature inside the refrigerated warehouse Tα
0 and the lower limit temperature T2.

Here, if the refrigerator internal temperature Tα is lower than Tz, the operation of the refrigeration equipment is stopped, and if it is higher, the Tα-
The temperature change ΔTl (=Tαo−Tz−1) of 1 is calculated, and the temperature inside the refrigerator T(210) after 10 minutes is predicted using the following equation.

Ta1o = 10 xΔTl+Tαo
'This predicted temperature Ta1O is the lower limit temperature T
If it is lower than 2, stop the operation of the refrigeration equipment, and if it is also higher, calculate the 10-minute average value Δ〒1 of the temperature changes ΔTl measured at 1-minute intervals. At this time, if Δ〒1 is negative, the operation of the refrigeration system is stopped, and if it is positive, the temperature TlZ40 after 40 minutes is approximately predicted using the following equation.

Ta4o=JgoCj　X　△Tx　+　Tz.

Here, if the temperature difference ΔT between Ta2 and Ta40 is larger than the specified temperature difference 05°C, the refrigeration equipment continues to operate, and if it is smaller, it is determined that Ta40 and the set temperature 'fs are the same, and T(Z40 is If it is higher than Ts, the refrigeration equipment continues to operate, and if it is lower than Ts, the refrigeration equipment is stopped.

With this control method, when the cooling capacity of the refrigeration equipment is considerably large relative to the cooling heat load of the refrigerated warehouse, the temperature changes Tα as shown in Fig. 5, and 10 minutes before reaching the lower limit temperature T2. Stop operation of the refrigeration equipment. Therefore, unnecessary operation of the refrigeration system can be prevented without overcooling to a level greater than the set temperature T3.

In addition, if the cooling capacity of the refrigeration system is similar to the cooling heat load of the refrigerated warehouse, a temperature change Tα as shown in FIG. 6 will be shown, and if this temperature is below the set temperature T9, the temperature will change.

Even if the temperature is higher than the lower limit temperature T2, if the temperature change over 40 minutes is 0.5°C or less, the operation of the refrigeration system is stopped.

Such control makes it possible to eliminate wasteful operation of the refrigeration system, making it possible to significantly reduce operating power costs as a whole.

In the embodiment described above, the temperature after 10 minutes and after 40 minutes was predicted, but the temperature may be controlled only by prediction after 40 minutes.

Also, in the same example, the temperature change used as the criterion for prediction after 10 minutes and 40 minutes was set at 0.5°C, but these values were chosen to be more appropriate for the cooling capacity and size of the refrigeration equipment. That's fine.

This invention makes it possible to eliminate unnecessary operations when cooling a refrigerated warehouse.

[Brief explanation of the drawing]

Figure 1 is a system diagram of a conventional refrigeration system, and Figures 2 and 2 are examples of temperature changes in a refrigerated warehouse due to conventional control methods. FIG. 3 is a system diagram of an embodiment of the refrigeration system according to the present invention;
FIG. 4 is a control flow diagram, FIG. 5 is an example of temperature change in a refrigerated warehouse according to the present invention, and FIG. 6 is another example. 10...Refrigerated warehouse-11...Compressor 12...Condenser 13...Expansion valve 14...Evaporator
15...Blower 16...Temperature detector 17
...Converter 18...flilJ control device 19...Microcomputer Ty...Set temperature
Tz... Upper limit temperature of the setting range T2... Lower limit temperature of the setting range Tα... Temperature inside the refrigerator Tα0...
Measured temperature ΔTl - temperature change for 1 minute (=Tao -Tα-1)
Talo... Predicted temperature after 10 minutes TcL40... Predicted temperature after 40 minutes Δ'r4o - Temperature change after 40 minutes (= Tao - Ta4
o).

Claims (1)

[Claims] 1. In a refrigeration system in which the air temperature of the refrigeration system can be controlled, a microcomputer is used to predict the air temperature a predetermined time after a change in the air temperature that has elapsed, and this predicted temperature is compared with the current temperature. A method for controlling a refrigeration system, characterized in that cooling by the refrigeration system is stopped when the predicted temperature is within a predetermined value and the predicted temperature is below a set value. 2 @Distribution When predicting the air temperature after a predetermined time, we predict the air temperature after two different predetermined times and give priority to control based on the predicted temperature after a short predetermined time of 2 hours over control based on other predicted temperatures. A method for controlling a refrigeration device according to claim 1.