JPH0611237A - Defrosting control device for show case - Google Patents

Abstract

PURPOSE:To prevent the temperature in the case from rising at the time of defrosting, and improve the freshness maintaining capability. CONSTITUTION:An outside temperature (e) is detected by an outside temperature sensor 7, and at the same time, a passed time (d) from the previous defrosting is measured by a passed time since defrosting counter 5 which is a timer. Based on the detected outside temperature (e) and passed time since defrosting (d), a most suitable dripping time (f) is calculated by a fuzzy inference unit, in response to the outside air and the condition of frosting. In addition, a dripping control unit 10 administrates the start and finish of 1 dripping by controlling the motions of a fan 11, heater 12 and valve 13 by an output unit 4 according to the calculated dripping time (f).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defrosting control device for a showcase that prevents the temperature inside the chamber from rising during and immediately after defrosting.

[0002]

2. Description of the Related Art Conventionally, in a showcase, in order to remove frost adhering to an evaporator, warm air heated by a heater or the like is sent to an evaporator to melt the frost and let it flow out.
The surface of the evaporator is dried by blowing air, which is called draining. This draining time is preset.

By the way, when the draining time is short, the drying is not completed and the cooling is restarted with the water still attached to the evaporator. Therefore, the attached water freezes and causes clogging. This clogging is called an ice bank, and if an ice bank occurs, the cooling capacity will be significantly impaired, and the products and showcases will be greatly damaged.

Further, if there is a large amount of frost, or if the frost is altered like ice over time, melting will be prolonged. Therefore, in the case where drainage is started before defrosting is completed, it must be completely melted by the end of drainage. For the above reasons, the drainage time is set as large as possible.

[0005]

As described above, if the draining time is set long with a margin, the drying is completed within the set draining time when the amount of frost is small or the outside temperature is high. The rest of the time unnecessarily raises the temperature inside the showcase. This deteriorates the freshness of the product and impairs the purchaser's willingness to purchase fresh products.

The present invention has been made to solve the above problems, and its purpose is to prevent hot air from being blown into the showcase cabinet for a longer time than necessary during defrosting. Another object of the present invention is to provide a defrost control device for a showcase, which can prevent the temperature inside the refrigerator from rising and prevent the deterioration of the freshness of products.

[0007]

In order to achieve the above object, the present invention provides a defrosting control device for a showcase, which heats and melts and removes the frost from the evaporator, and then dry it by blowing air to drain the water. , A temperature sensor that detects the outside air temperature, a timer that measures the elapsed time from the previous defrosting, and a fuzzy inference unit that calculates the optimum draining time according to the outside air condition and the frosted condition based on the outside air temperature and the elapsed time. And a means for controlling the air blowing time based on the calculated draining time.

[0008]

In the present invention, the outside air temperature is detected by the temperature sensor and the elapsed time from the previous defrosting is measured by the timer. Based on the detected outside air temperature and elapsed time, the fuzzy inference unit calculates the optimum draining time according to the outside air and the frosted state. Further, the air blowing time for draining is controlled based on the calculated draining time.

[0009]

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 the present invention. In the figure, 1 is a defrosting starter, which sends a defrosting start signal a to the showcase controller 2. When the showcase control device 2 receives the defrosting start signal a, the defrosting control unit 3
And sends the defrosting ON signal b to the output unit 4. Further, when the defrosting control unit 3 determines the end of defrosting from the temperature information of the showcase, it sends a defrosting OFF signal c to the output unit 4.

The defrost elapsed time counter 5, which is a timer, measures the defrost elapsed time d from the start of the previous defrost to the start of the present defrost and sends it to the fuzzy inference unit 6. The outside air temperature sensor 7 detects the outside air temperature e and detects the fuzzy inference unit 6
Send to. The fuzzy inference unit 6 determines the membership function 8 and the rule 9 based on the defrost elapsed time d and the outside air temperature e.
The state of frost on the evaporator (not shown) is estimated by fuzzy inference using, and the optimum drainage time f is calculated according to the current outside air temperature and sent to the drainage controller 10.

The membership function 8 is a membership function for judging a state such as "short" or "high" with respect to the input values of the defrosting elapsed time d and the outside air temperature e. Rule 9 is created based on the following concept. (1) If the defrost elapsed time is short, the amount of water that adheres to the evaporator after defrosting is small or the defrosting is incomplete because the amount of frost is small or the amount of frost that is easily melted is large. Decrease the risk of ending and shorten the draining time.

(2) When the defrosting elapsed time is long, the amount of water that adheres to the evaporator after defrosting is large because the amount of water that adheres to the evaporator after defrosting is large, or even if there is a small amount of frost, the frost is transformed and hardly melts Decrease the risk of incomplete defrosting and increase the draining time. (3) When the outside air temperature is high, the water is easily dried, so the draining time is shortened. (4) If the outside air temperature is low, it will be difficult to dry, so make the draining time longer. Table 1 summarizes these concepts in IF-THEN format rules.

[0013]

[Table 1]

The drainer control unit 10 sends a drainer ON signal g to the output unit 4 at the end of defrosting and also turns on the drainer ON.
After the output of the signal g, when the draining time f has elapsed, draining
The OFF signal h is sent to the output unit 4. The output unit 4 starts / stops signals i, j, k at the timings when the defrosting ON signal b, the defrosting OFF signal c, the drainage ON signal g, and the drainage OFF signal h are input.
To generate a fan 11, a heater 12, and a valve 1, respectively.
Send to 3. The fan 11 is for sending cold air during normal operation and for sending hot air during defrosting, the heater 12 is for heating the airflow during defrosting, and the valve 13 is for turning on the refrigerant supply to the evaporator. It is for turning off.

With the configuration of the embodiment as described above, the state of frost at the start of defrosting is estimated by the defrosting elapsed time d, and the ease of drying the evaporator is estimated by the outside air temperature e. Accordingly, the optimum drainage time f without excess or deficiency is obtained, and it becomes possible to finish the drainage at an appropriate timing, and it is possible to prevent an unnecessary rise in the internal temperature during draining and immediately after the draining.

2 to 4 show the membership function 8 of FIG.
The specific content of is shown. FIG. 2 is a membership function for the defrosting elapsed time d of the antecedent part. FIG. 3 is a membership function for the outside air temperature e in the antecedent part. Figure 4
Is a membership function for the drainage time f of the consequent part.

In this embodiment, the frosting state at the start of defrosting is estimated, and the draining time is determined by grasping the state of the air for drying the water adhering to the evaporator, that is, the outside air, and the draining is executed accordingly. Therefore, it is possible to perform draining without excess or deficiency. As a result, it is possible to prevent an unnecessary increase in the temperature inside the refrigerator, and to suppress the loss of the purchaser's willingness to purchase and the deterioration of the freshness of the product.

Not only that, but a new showcase defrosting control system which guarantees the safety when defrosting is not completely performed as compared with the conventional technique can be established. In addition, in the embodiment, the state of the outside air is detected only by the temperature, but the humidity can also be detected to improve the control accuracy.

[0019]

As described above, according to the present invention, the fuzzy reasoning based on the outside air temperature and the elapsed time from the previous defrosting makes it possible to obtain the draining time and optimize the blowing time. As a result, after defrosting, excess air is not blown and unnecessary increase in the temperature inside the showcase is eliminated.
The freshness of the product can last longer.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a membership function set for a defrosting elapsed time.

FIG. 3 is a diagram showing a membership function set for an outside air temperature.

FIG. 4 is a diagram showing a membership function set for draining time.

[Explanation of symbols]

 1 Defrost Starter 2 Showcase Control Device 3 Defrost Control Unit 4 Output Unit 5 Defrost Elapsed Time Counter 6 Fuzzy Inference Unit 7 Outside Air Temperature Sensor 8 Membership Function 9 Rules 10 Drain Control Unit 11 Fan 12 Heater 13 Valve

Claims (1)

[Claims] 1. A defrost control device for a showcase, which heats and melts and removes frost from an evaporator, then dries by blowing air to remove water, and a defrost control device for a showcase that detects an outside air temperature and a defrost control from the previous defrost. A timer that measures the elapsed time, a fuzzy inference unit that calculates the optimum draining time according to the outside air temperature and the frosting state based on the outside air temperature and the elapsed time, and a means that controls the air blowing time based on the calculated draining time. A defrost control device for a showcase, comprising: