JPH06109350A - Temperature controller for showcase - Google Patents

Abstract

PURPOSE:To keep the storage chamber temperature constant even when the outside air or the load changes. CONSTITUTION:An operating time rate calculator 1 obtains the operating time rate (a) of the refrigerating machine and sends it to a fuzzy inference part 5. An outside air temperature-measuring device 2 and an outside air humidity- measuring device 3 detect respectively the outside air temperature (b) and the outside air humidity (c) both with respect to the air around the showcase and send the results to an enthalpy operator 4. From the outside air temperature (b) and the outside air humidity (c) the enthalpy operator 4 calculates the enthalpy (d) of the outside air and sends the result to the fuzzy inference part 5. By fuzzy inference based on the operating time rate (a) and the enthalpy (d) the fuzzy inference part 5 obtains an adjusted value (e) and sends it to a set value-operator 8. The set value-operator 8 converts the adjusted value (e) to a set value (f) and sends it to a refrigerating machine controller 9. On the basis of the set value (f) the refrigerating machine controller 9 alters the value set for the temperature inside the showcase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device for a showcase.

[0002]

2. Description of the Related Art Conventionally, as a temperature control device for a showcase for refrigeration, an outlet side temperature of an evaporator is detected and compared with a set temperature, and a solenoid valve installed in a refrigerant supply path to the evaporator is opened or closed. By closing, the cold air temperature in the refrigerator is kept constant. However, in the case of the open showcase, since the heat quantity easily flows into the interior from the outside, the temperature tends to rise during the day due to the rise in the outside temperature, and tends to fall during the night due to the fall in the outside temperature. . Therefore, at night, the showcase may be covered with a night cover, or the temperature may be controlled by changing the set temperature between night and day.

As described above, even if the set temperature is changed between day and night, the set temperature is simply set in two stages of day and night, so that it is difficult to always keep the temperature inside the chamber constant. Therefore, in order to maintain the temperature inside the refrigerator with high accuracy, a method has been proposed in which the set temperature is changed according to the operating time rate of the refrigerator (ratio of the opening time of the solenoid valve). This operating method considers that the load is large when the operating time rate is large, and lowers the set temperature, and when the operating time rate is small, it is considered that the load is small and the set temperature is raised, so that It becomes possible to drive.

[0004]

However, even in the case of the operation in which the set temperature is changed according to the operating time rate, the operating time rate is significantly increased depending on the amount of frost on the evaporator even under the same outside air conditions. May change to. Therefore, it was difficult to keep the internal temperature constant with satisfactory accuracy. In other words, there is a problem that the temperature inside the store rises due to a change in the amount of frost, which accelerates deterioration of the freshness of the displayed products.

The present invention has been made to solve the above problems, and an object of the present invention is to keep the temperature inside the chamber constant even when the amount of frost on the evaporator is not uniform, and to improve reliability and reliability. It is an object of the present invention to provide a temperature control device for a showcase that can perform temperature control with excellent efficiency.

[0006]

In order to achieve the above object, the present invention provides a temperature controller for a showcase, in which a refrigerator is activated to keep a constant temperature inside the refrigerator when the temperature inside the refrigerator exceeds a set temperature. , Means for calculating the operating time rate of the refrigerator,
A temperature sensor that detects the outside temperature, a humidity sensor that detects the outside humidity, a means that calculates the enthalpy of the outside air from the temperature and humidity of the outside air, and a set temperature change value based on fuzzy inference from the operating time rate and the enthalpy of the outside air. And means for changing the set temperature of the refrigerator according to the set temperature change value.

[0007]

In the present invention, the operating time rate of the refrigerator is calculated and the temperature and humidity of the outside air are detected by the temperature sensor and the humidity sensor. The outside air enthalpy is calculated from the outside air temperature and humidity. The set temperature change value is calculated based on the fuzzy inference from the operating time rate and the outside air enthalpy. The set temperature of the refrigerator is changed according to the set temperature change value.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of a temperature control device for a showcase according to the present invention. In the figure, 1
Is an operating time rate calculation device, measures the operating time of the refrigerator, calculates the operating time rate a, and sends it to the fuzzy inference unit 5.

The outside air temperature measuring device 2 measures the outside air temperature b around the showcase and sends it to the enthalpy calculating section 4. The outside air humidity measuring device 3 measures the outside air humidity c around the showcase and sends it to the enthalpy computing unit 4. The enthalpy calculation unit 4 calculates the enthalpy d of the outside air from the outside air temperature b and the outside air humidity c and sends it to the fuzzy inference unit 5.

The fuzzy inference unit 5 obtains the adjusted value e of the set temperature by the fuzzy inference using the control rule 6 and the membership function 7 based on the operating time rate a and the enthalpy d and sends it to the set value computing unit 8. . The control rule 6 is a rule in which the value of the adjustment value e that indicates the fluctuation range of the set temperature in the thermostat operation is determined with respect to the operating time rate a and the enthalpy d input to the fuzzy inference unit 5, and the content thereof is It looks like this:

(1) When the enthalpy of the ambient air is small, the adjustment value is lowered. (2) If the enthalpy of the ambient air is large, increase the adjustment value. (3) When the operating time ratio of the refrigerator is low, lower the adjustment value. (4) When the operating time rate of the refrigerator is high, increase the adjustment value. Table 1 shows a control rule 6 which is a combination of these values in five specific levels.

[0012]

[Table 1]

The membership function 7 is an IF section membership function that defines the degree of conformity to the driving time rate a and the enthalpy d input to the fuzzy reasoning section 5, and an adjustment value e.
And a membership function that determines the. The set value calculator 8 converts the adjustment value e into a set value f and sends the set value f to the refrigerator controller 9. Here, the setting value f is changed when the adjustment value e exceeds a preset fluctuation range. Thereby, the fluctuation of the set value f with respect to the change of the adjustment value e becomes a hysteresis curve, and the small fluctuations of the set value f are eliminated.

When the set value f instructing the change of the set temperature is input, the refrigerator controller 9 changes the set temperature of the thermostat operation. FIG. 2 shows the membership function for the enthalpy d applied to the IF part of control rule 6. Figure 3
Shows the membership function for the operating time rate a of the refrigerator applied to the IF section of control rule 6. FIG. 4 shows a membership function for the adjustment value e applied to the THEN part of the control rule 6.

In the embodiment constructed as described above, the enthalpy is used to judge whether the surrounding environment is high temperature and high humidity or low temperature and low humidity, and the heat exchange state of the evaporator is regarded as the operating time ratio of the refrigerator. By making a comprehensive judgment of them, it becomes possible to adjust the set temperature to an optimum value so that the internal cold storage temperature is always constant. Thereby,
Even if there is a temperature change in the outside air during the day and night and in the summer and winter, or if there is a change in the amount of frost formed on the evaporator, the temperature inside the refrigerator is always constant. As a result, the temperature inside the refrigerator is prevented from unnecessarily rising, energy-saving operation becomes possible, and the deterioration of the freshness of the product slows down.

Further, even if an error or malfunction occurs in the measurement of the outside air temperature, the humidity, or the operating time rate, it is possible to continue the operation close to normal by being compensated by the determination of the change in the other measured values. , System reliability is also improved. In the embodiment, the enthalpy d is calculated from the temperature b and the humidity c of the outside air and input to the fuzzy inference unit 5.
It is also possible to directly input the temperature b and the humidity c of the outside air into the fuzzy inference unit 5 by increasing the number of control rules 6.

[0017]

As described above, according to the present invention, the set temperature change value is calculated based on the fuzzy inference from the operating time rate of the refrigerator and the enthalpy obtained from the temperature and humidity of the outside air. The set temperature of the refrigerator is changed according to the set temperature change value. As a result, even when the outside air conditions and the amount of frost on the evaporator are not uniform, the temperature inside the refrigerator is kept constant, and temperature control with excellent reliability and efficiency is performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an exemplary embodiment according to the present invention.

FIG. 2 is a diagram showing a membership function for enthalpy of a control rule.

FIG. 3 is a diagram showing a membership function with respect to an operating time rate of a control rule.

FIG. 4 is a diagram showing a membership function for an adjustment value of a control rule.

[Explanation of symbols]

 1 Operating time rate calculation device 2 Outside air temperature measurement device 3 Outside air humidity measurement device 4 Enthalpy calculation unit 5 Fuzzy inference unit 6 Control rules 7 Membership function 8 Set value calculation unit 9 Refrigerator control unit

Claims (1)

[Claims] 1. A temperature controller for a showcase, which starts a refrigerator when the temperature inside the refrigerator exceeds a set temperature to keep the temperature inside the refrigerator constant, and a means for calculating an operating time ratio of the refrigerator and an outside air temperature. A temperature sensor that detects the temperature, a humidity sensor that detects the humidity of the outside air, a means to calculate the enthalpy of the outside air from the temperature and humidity of the outside air, and a set temperature change value based on the fuzzy inference from the operating time rate and the enthalpy of the outside air. A temperature control device for a showcase, comprising: means and means for changing the set temperature of the refrigerator according to the set temperature change value.