JPH11173740A - Method and device for controlling defrosting of refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling the defrosting of a refrigerator for judging defrosting time relatively simply and effectively. SOLUTION: A plurality of utilization condition cases are divided according to outside air temperature to and the number of the opening a door Cdo in advance. Each case has a stage S6 for determining a degree-of-severity value Sf, a stage S3 for measuring outside air temperature t0 of a cabinet, the number of the opening of the door Cdo, and the up-time tc of a compressor, a stage S7 for obtaining frost-stuck weight De by multiplying the degree-of-severity value Sf by the on-time tc of the compressor, and a stage S9 for executing S8, i.e., defrosting action, when a total frost weight De exceeds a specific value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling defrosting of a refrigerator.

[0002]

2. Description of the Related Art A refrigerator generally includes a cabinet forming a food storage room such as a refrigerator room and a freezer room, and doors respectively attached to the refrigerator room and the freezer room. A refrigeration system is provided for cooling the food contained in the room. The refrigeration system includes a compressor that compresses a refrigerant, a condenser that condenses the refrigerant from the compressor, and an evaporator that evaporates the refrigerant from the condenser to generate cool air. The evaporator cools the surrounding air by the latent heat of evaporation of the refrigerant flowing inside the evaporator, and the cool air is supplied to a freezing room or a refrigerating room by a blower fan.

In such a refrigerator, moisture condenses on the surface of the evaporator due to a difference in relative humidity between the surface of the low-temperature evaporator and the high-temperature surrounding air, and freezes to generate frost, which accumulates on the surface of the evaporator. Frost impedes the heat exchange of the evaporator and reduces the effective cooling function, while increasing the power consumption. Therefore, in recent refrigerators, a defrost heater is installed adjacent to the evaporator, and the defrost heater is operated periodically or at a predetermined defrost time to melt the frost accumulated in the evaporator. Has been removed.

[0004] The formation of frost on the evaporator is caused by the operation of the refrigeration system,
That is, it increases in proportion to the operation time of the compressor, and increases as the inflow of outside air due to the opening of the door increases. That is, the amount of frost is affected by the compressor operating time, the number of times the door is opened, the door opening time, and the outside air temperature. In view of these points, various forms of defrosting time determination methods have been proposed. US4,29
In 7,852, the operating time of the compressor and the opening time of the door are accumulated, and when the accumulated operating time of the compressor reaches a predetermined time after a lapse of a predetermined time or more, it is determined that the defrost timing is reached. It can be said that this prior art does not consider the effect of the outside air temperature.

The defrosting control device disclosed in US Pat. No. 5,564,286 is provided with a compressor operating time timer, a door opening counter, a door opening timer, and an outside air temperature sensor, and uses input values from these. The defrost timing is determined by the fuzzy logic inference method. Here, the defrost cycle is determined based on the outside air temperature and the number of times the door has been opened after the compressor operation time has elapsed for a predetermined time or more. If the accumulated value of the door opening time is equal to or longer than a predetermined value, the defrosting is performed irrespective of other use conditions. However, this prior art has a disadvantage that the process of determining the defrost timing is relatively complicated.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a refrigerator defrosting control method and a defrosting control device capable of effectively determining the defrosting timing while being relatively simple. Things.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided, in accordance with the present invention, a cabinet forming a food storage room, a door of the food storage room, a compressor for compressing a refrigerant, an evaporator, and a defroster for the evaporator. A method of controlling defrosting of a refrigerator equipped with a defrosting heater for separating multiple use condition cases in advance according to the outside air temperature per unit time and the number of times the door is opened, and determining the severity value for each use condition case. Determining, measuring the outside air temperature of the cabinet, the number of times the door is opened, and the operation time of the compressor per unit time; and the severity of the use condition case according to the outside air temperature and the number of times the door is opened. Multiplying the value by the compressor operating time to determine a frost weight per unit time; accumulating the unit frost weights over a plurality of unit times to determine a total frost weight; Is achieved by refrigerator defrosting control method characterized by comprising the step of executing the defrosting operation, when the.

Here, the method includes a step of measuring a door opening time every time the door is opened, and a step of increasing the number of times of opening the door by one each time the measured door opening time exceeds a predetermined time. Thereby, the door opening time can be appropriately reflected in the defrost cycle determination. Then, the severity value sets the corresponding defrost cycle when each of the operation condition cases continues,
It can be set by giving the severity value as a reciprocal value of the defrost cycle of the case.

Another object of the present invention is to provide a cabinet that forms a food storage room, a door of the food storage room, a compressor for compressing a refrigerant, an evaporator, and a defrost heater for defrosting the evaporator. In the refrigerator defrosting control device provided, an outside air temperature sensor for detecting an external temperature of the cabinet, a door opening counter for counting the number of times the door has been opened, and a compressor operation timer for measuring an operation time of the compressor. Based on the outside air temperature per unit time and the number of times the doors are opened, the severity of the operating condition set in advance is multiplied by the operation time of the compressor to obtain a frost weight per unit time, and each unit frost is calculated. A defrosting control device for a refrigerator, comprising: a controller that accumulates weights for a plurality of unit times and executes a defrosting operation when the total frosting weight is equal to or greater than a predetermined value.

[0010]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a sectional view of a refrigerator provided with a defrost control device according to the present invention. In the refrigerator cabinet (1), an upper freezer compartment (2) and a lower refrigerating compartment (3) are formed with a partition (5) therebetween. Doors (6, 7) are attached to the freezer compartment (2) and the refrigerator compartment (3), respectively.

The refrigerator shown in the drawing is of a so-called independent cooling type. In the freezer compartment (2) and the refrigerator compartment (3), an independent freezer compartment evaporator (10) and a refrigerator compartment evaporator (1) are provided.
3) is attached. The refrigerant from the compressor (9) for compressing the refrigerant passes through a condenser (not shown) and is connected to the freezer compartment (2) and the refrigerator compartment (3).
0) and the refrigerator compartment evaporator (13). The cool air generated from each evaporator (10, 13) is cooled by a blower fan (11, 14) into a freezing room (2) and a refrigerator room (3).
Provided to Defrosting heaters (12, 15) for defrosting the corresponding evaporators (10, 13) are installed below the freezer evaporator (10) and the refrigerator compartment evaporator (13), respectively.

Door switches (17, 18) which are turned on and off in conjunction with opening and closing of the corresponding doors (6, 7) are installed in the door opening areas of the freezer compartment (2) and the refrigerator compartment (3), respectively. I have. The detection signals of these door switches (17, 18) are transmitted to a door opening counter described later.

The defrosting device according to the present invention is not limited to the independent cooling type refrigerator as shown in the drawing. In the following, for convenience in the description, the present defrost control device will be described as controlling only the defrost of the freezer evaporator (10).

FIG. 2 is a schematic block diagram of a defrost control device according to the present invention. As can be seen from this figure, the present defrost control device includes a control unit (20) that controls a defrost heater (12), an outside air temperature sensor (23) that provides an input signal to the control unit (20), Door opening counter (2
4) A door opening timer (25) and a compressor operation timer (26) are provided.

The outside air temperature sensor (23) detects the temperature outside the cabinet (1) and provides a detection signal to the control unit (20). The door opening counter (24) counts the number of times the door is opened based on the detection signal from the door switch (17), and the door opening timer (25) measures the opening duration for each opening of the door. (20)
To communicate. The compressor operation timer (26) accumulates the operation time of the compressor (9) that operates intermittently depending on the room temperature.

The control unit (20) also stores information on a plurality of use condition cases classified according to the use conditions of the refrigerator. The use condition cases can be classified into, for example, a form as shown in FIG.

The table of FIG. 3 shows an example in which the use condition cases are divided considerably for simplicity of explanation of the present invention. Here, each case is classified based on the results of the experiment. If the number of doors opened per unit time is 5 or more in a state where the outside air is high temperature, cases 1 and 5 are used.
If the number of times of door opening is less than 5 times, the case is classified as Case 2; if the temperature is outside the room temperature, the case is regarded as Case 2 regardless of the number of times of door opening; Then, when the use conditions corresponding to each case continue, the total cumulative operation time of the compressor is:
For example, suppose that defrost must be started when the time reaches 6, 12 and 16 hours. That is, the defrost cycle is set shorter as the number of times the door is opened is higher at a higher outside air temperature, and the defrost cycle is set longer as the number of times the door is opened is lower at a lower outside temperature. The reciprocal value of the defrost cycle of each case, that is, 1/6, 1/12, or 1/16 means the severity of the use condition of the case. Needless to say, the division of the use condition cases can be subdivided at any time as required from the example of FIG.

The control section (20) receives a signal about the door opening time inputted from the door opening timer (25), and when the door opening time is longer than a predetermined time, for example, 15
If it is longer than one second, it is considered that the door has been opened once more, and the number of times of door opening from the door opening counter (24) is increased. For example, if the door is kept open for 50 seconds with one opening, it is counted as having been opened four times in total.

In this way, the control unit (20) determines the use condition case at that time for each unit time, for example, every hour from the table of FIG. 3 based on the door open count value and the outside air temperature value. . By multiplying the severity corresponding to the selected case, that is, the reciprocal value of the defrost cycle by the cumulative operating time of the compressor per unit time provided from the compressor operating timer (26), The frosting weight can be determined. When the frosting weight per unit time is accumulated and the value exceeds 1, it is determined that the defrost timing is reached.

For example, during the first hour, the compressor operates for 0.5 hours under the conditions of Case 2, and during the second hour, the compressor operates for 0.5 hours under the conditions of Case 1. In this case, the cumulative value of the frost weight value is 0.5 / 12 + 0.5 / 6 = 1.
It becomes 5/12. In this way, the frosting weight value per unit time is continuously accumulated, and if the accumulated total gross weight exceeds 1, it is determined that the defrost timing has been reached.

FIG. 4 shows the flow of the defrosting method according to the present invention. When the operation of the refrigerator is started, the frosting weight value (De) is reset to zero (SI), and the compressor operation time (tc), the number of times of door opening (Cdo) and the door opening time (tdo) are set to zero. (S2). For the subsequent unit time, for example, for one hour, the outside air temperature (To), the number of times the door has been opened are determined by the outside air temperature sensor (23), the door opening counter (24), the door opening timer (25), and the compressor operation timer (26). (Cd
o), the door opening time (tdo) and the compressor operating time (tc) are measured (S3), and provided to the control unit (20). The controller (20) detects the outside air temperature (To) per unit time only once through the outside air temperature sensor (23), or uses the averaged value of multiple times as the outside air temperature (To). .

The control section (20) converts the door opening time (tdo) detected in the step S3 as the number of times of door opening to obtain a converted number of times of door opening (Cdc) (S4). That is, as described above, every time the door is opened, the converted door opening count (Cdc) is increased by one each time the opening time exceeds, for example, 15 seconds. Number of door open times detected by the door open counter (24) (Cd
o) plus the converted door open count (Cdc) to add the door open count (Cdo)
(S5), door open count (Cdo) and outside air temperature (To)
Then, for example, the use condition case is determined in accordance with the case classification criterion as shown in FIG. 3, and the severity (Sf) in the use condition case is selected (S6). After multiplying the severity (Sf) by the compressor operating time per unit time (tc) to obtain a unit frost weight, this is used as the previous total frost weight value.
(De) is accumulated (S7). If the total frost weight value (De) is 1 or less, the steps from S2 to S8 for obtaining the frost weight and the total frost weight value (De) in the next unit time are repeated again. If the total frosting weight (De) exceeds 1 from step S7, it is determined that the defrost timing has been reached, and the defrost operation is executed (S7).
9) When the defrosting operation is completed, the process returns to the beginning.

[0023]

As described above, according to the defrosting control apparatus and method of the present invention, the frosting weight per unit time is determined based on the outside air temperature, the number of times the door is opened, the door opening time and the compressor operating time. Then, it is determined whether the defrosting time has been reached by accumulating the frosting weights. Therefore, it is possible to effectively determine the defrost timing by a relatively simple algorithm, taking into account all factors that affect the amount of frost.

[Brief description of the drawings]

FIG. 1 is a sectional view of a refrigerator provided with a defrost control device according to the present invention.

FIG. 2 is a schematic block diagram of a defrost control device according to the present invention.

FIG. 3 is a diagram showing an example of a classification table of use condition cases.

FIG. 4 is a diagram showing a flowchart of a defrost control method according to the present invention.

[Explanation of symbols]

 Cdo Door opening times De Frost weight Sf Severity value tc Compressor operation time tdo Door opening time to outside air temperature

Claims (6)

[Claims] 1. A cabinet forming a food storage room;
Food storage room door, refrigerant compression compressor, evaporator,
In a defrosting control method for a refrigerator provided with a defrosting heater for defrosting an evaporator, a plurality of use condition cases are classified in advance according to an outside air temperature per unit time and a number of times of opening of a door, Separately determining the severity value; measuring the outside air temperature of the cabinet, the number of times the door is opened and the operating time of the compressor per unit time; and the use according to the outside air temperature and the number of times the door is opened. Multiplying the operating time of the compressor by the severity value of the condition case to obtain a frost weight per unit time; and accumulating the frost weights for a plurality of unit times to obtain a total frost weight. Performing a defrosting operation when the total frosting weight is equal to or greater than a predetermined value. 2. A step of measuring a door opening time every time the door is opened, and increasing the number of times of door opening by one each time the measured door opening time exceeds a predetermined time. The method for controlling defrosting of a refrigerator according to claim 1, comprising: 3. The method according to claim 2, wherein the predetermined time is 10 to 20 seconds. 4. A step of setting a corresponding defrost cycle when each of the use condition cases continues, and a step of giving the severity value as a reciprocal value of the defrost cycle of the corresponding use condition case. The method for controlling defrosting of a refrigerator according to claim 1, wherein: 5. A cabinet forming a food storage room,
Food storage room door, refrigerant compression compressor, evaporator,
In a defrost control device for a refrigerator including a defrost heater for defrosting an evaporator, an outside air temperature sensor that detects an external temperature of the cabinet, a door opening counter that counts the number of times the door is opened, A compressor operation timer for measuring the operation time of the compressor, and a unit time obtained by multiplying the operating time of the compressor by the operating condition severity set in advance based on the outside air temperature per unit time and the number of door open times. A defrosting weight per unit, accumulating each unit frosting weight over a plurality of unit times, and performing a defrosting operation when the total frosting weight is equal to or more than a predetermined value. Refrigeration defrosting control device. 6. A door opening timer for measuring an opening time of the door, wherein the control unit increases the number of times of opening the door by one every time the opening time of the door exceeds a predetermined time.
6. The defrosting control device for a refrigerator according to claim 5, wherein the number is increased every time.