JPH0634259A - Electrical refrigerator - Google Patents

Abstract

PURPOSE:To reduce a defrosting operation time and further reduce the increase in temperature in a freezing chamber. CONSTITUTION:An electrical refrigerator has a freezing chamber 1 and a refrigeration chamber 2. There is provided an evaporator 4 for generating cold air at a rear part of the freezing chamber 1. The cold air generated at the evaporator 4 is sent out to the freezing chamber 1 under an operation of a blower 5 and concurrently the cold air is sent into the refrigeration chamber 2 and a vegetable chamber 3 through a cold air distributing chamber 6 and a cold air duct 7. Since the cold air returning from the refrigeration chamber 2 toward the evaporator 4 accompanies with wet air, frost is generated at the surface of the evaporator 4. As this amount of frost is increased, a heat exchanging performance of the evaporator 4 is reduced. Then, as an operation calculating time of a compressor 12 reaches a predetermined value, operations of the compressor 12 and the blower 5 are stopped, electrical power is supplied to a defrosting heater 10 so as to perform the defrosting operation. As the defrosting operation is started, the temperature of the evaporator 4 is detected by a temperature sensor 11, and a temperature variation rate of the evaporator 4 is repeated for very predetermined time so as to calculate it. If the temperature variation is less than a predetermined reference value, a heat generating amount of the defrosting heater 10 is increased and if the temperature variation exceeds the reference value, the heating amount of the defrosting heater 10 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defrosting operation of an electric refrigerator.

[0002]

2. Description of the Related Art An electric refrigerator includes a freezing room, a refrigerating room, a vegetable room, etc., and an evaporator for generating cold air is arranged behind the freezing room. The cool air generated by this evaporator is supplied to the freezer compartment by the blower, and is also supplied to the refrigerating compartment and the vegetable compartment through the cool air duct connected to the cool air distribution compartment at the rear of the freezer compartment, and is supplied to each of these compartments. The cold air is returned to the evaporator through a cold air return passage formed on a partition wall between the freezer compartment and the refrigerator compartment. By the way, the temperature of the evaporator drops to about -30 ° C during operation of the compressor,
On the other hand, the cool air returned to the evaporator through the cool air return passage is 5
Since the temperature has risen to 7 ° C and is accompanied by humidity, frost is generated on the surface of the evaporator. The amount of frost increases as the operating cumulative time of the compressor becomes longer, resulting in dew condensation. When the evaporator is in such a state, the heat exchange performance deteriorates, so conventionally, when the accumulated operating time of the compressor reaches a predetermined value, the operation of the compressor is stopped, and the defrosting placed under the evaporator is defrosted. The heater for electricity was energized, and the heat generated was used to perform defrosting operation to melt the frost adhering to the evaporator.

[0003]

However, in the conventional defrosting operation, since the output of the defrosting heater is constant from the start to the end of the defrosting operation, after the defrosting has progressed to some extent, the frost of the evaporator is defrosted. The output of the defrosting heater tends to be too large with respect to the remaining amount, and as a result, there is a problem that the temperature of the freezing room rises excessively when the defrosting operation ends. Therefore, it is an object of the present invention to provide an electric refrigerator that does not cause such a problem.

[0004]

The present invention has been made to solve the above problems, and when the operation accumulated time of the compressor reaches a predetermined time, energization of the defrosting heater is started, In an electric refrigerator configured to stop energizing the defrosting heater when the temperature of the evaporator detected by the temperature sensor reaches a preset temperature for ending the defrosting operation, When energization is started, the temperature change of the evaporator is obtained every predetermined time, and when the temperature change is below a predetermined value, the output of the defrosting heater is increased, and when the temperature change exceeds a predetermined value, the defrosting is performed. It was decided to control the output of the heater for use to be small.

[0005]

With the above configuration and control method, the defrosting heater output is large in the first half of the defrosting operation that requires a larger amount of heat generation, so the defrosting time can be shortened.
In the latter half of the defrosting operation in which the amount of heat generation is small, the output of the defrosting heater is small, so that excessive heat generation is eliminated and it is possible to prevent an excessive temperature rise in the freezer compartment.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a side sectional view showing a schematic configuration of an electric refrigerator, 1 is a freezer compartment, 2 is a refrigerating compartment, and 3 is a vegetable compartment.
Behind the freezer compartment 1 is an evaporator 4 and a blower 5 for sending the cold air generated by the evaporator 4 to each of the compartments 1 to 3, and the cold air to the refrigerating compartment 2 and the vegetable compartment 3 is the freezing compartment 1 It is sent through a cold air duct 7 connected to a rear cold air distribution chamber 6. The cold air sent into each of the chambers 1 to 3 is configured to be returned to the evaporator 4 through cold air return passages 8a and 8b formed in a partition wall 8 that partitions the freezing chamber 1 and the refrigerating chamber 2. Further, the partition wall 8 has an evaporator 4 during defrosting operation.
Gutter part (drain gutter) for collecting defrost water flowing from the side 9
There is a defrosting heater 10 which is energized at the time of defrosting operation. The upper evaporator 4 has a temperature sensor for detecting the temperature of the evaporator 4.
11 are provided.

The temperature information of the evaporator 4 detected by the temperature sensor 11 is input to the controller 13 which controls the blower 5, the compressor 12 and the like as shown in FIG. The control unit 13 includes an A / D conversion unit 14 that converts an input signal (analog signal) from the temperature sensor 11 into a digital signal, a storage unit 15 that temporarily stores the A / D-converted temperature data, and the storage unit 15. Is newly detected by the temperature data and the temperature sensor 11 stored in
The calculation unit 16 for calculating the temperature change (rate of temperature change) Δt ° C. per unit time of the evaporator 4 based on the temperature data obtained by the D / D conversion, and the temperature change Δt ° C. calculated by the calculation unit 16 are large. Storage unit 17 that stores a reference value used to determine whether the value is smaller, a comparison unit 18 that compares the reference value stored in this storage unit 17 with the output Δt ° C from the calculation unit 16, and this comparison It is composed of an operation control unit 19 or the like having a function of determining the amount of power supplied to the defrosting heater 10 based on the comparison result in the unit 18, a timer function of integrating the operating time of the compressor 12, and the like. The operation control unit 19 is provided in the power supply circuit of the defrosting heater 10 after stopping the operation of the blower 5 and the compressor 12 for the defrosting operation when the accumulated operating time of the compressor 12 reaches a predetermined time. To control the switching element 20 that is operating to supply power to the defrosting heater 10. You have me.

A method of supplying electric power to the defrosting heater 10 will be described below with reference to FIG. FIG. 3 shows how the temperature of the evaporator 4 changes after the defrosting operation starts and how to energize the defrosting heater 10. Energization of the defrosting heater 10 is started at the defrosting start time t1. The temperature of the evaporator 4 detected by the temperature sensor 11 rises as shown in FIG. The temperature of the evaporator 4 is detected every predetermined time, and the calculation unit 16 repeatedly obtains the temperature change Δt ° C. per unit time. This temperature change Δt ° C. is compared with the reference value stored in the storage unit 17 by the comparison unit 18, and if the temperature change Δt ° C. of the evaporator 4 is less than or equal to the reference value, the operation control unit 19 causes the defrosting heater 10 to operate. The switching element (triac) 20 is controlled so as to maintain a large output, and when the temperature change Δt ° C of the evaporator 4 exceeds the reference value at time t2, the operation control unit 19 causes the output of the defrosting heater 10 to change. Switching element to make it smaller
Control twenty. Then, when the temperature of the evaporator 4 reaches the preset defrosting operation end temperature at the time t3, that is, the energization stop temperature of the defrosting heater 10, the operation control unit 19 controls the switching element 20. Stop the power supply to the defrosting heater 10 and stop the compressor that had been stopped until then.
It is designed to restart the operation of 12 mag.

[0009]

As described above, in the electric refrigerator constructed as described above, in the defrosting operation, the frost is rapidly melted with a large amount of heat in the initial stage when a large amount of frost is attached to the evaporator. It is possible to reduce the heat generation amount of the defrosting heater in the latter stage where the amount of frost is reduced, and it is possible to defrost using the residual heat in the previous stage as well, so that the defrosting operation time can be shortened and the freezer compartment side can be shortened. The excessive temperature rise of is suppressed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of the inside of an electric refrigerator according to the present invention.

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

FIG. 3 is a time chart for explaining the operation of the defrosting heater according to the present invention.

[Explanation of symbols]

 1 Freezer 2 Refrigerator 4 Evaporator 5 Blower 6 Cold air distribution chamber 9 Gutter (drain gutter) 10 Defrost heater 11 Temperature sensor 12 Compressor 13 Controller 20 Switching element 21 AC power supply

Claims (2)

[Claims] 1. When the accumulated operating time of the compressor reaches a predetermined time, energization of the defrosting heater is started, and the temperature of the evaporator detected by the temperature sensor is the preset temperature at the end of the defrosting operation. In an electric refrigerator configured to stop energizing the defrosting heater when the temperature reaches, when the energizing of the defrosting heater is started, the temperature change of the evaporator is obtained at predetermined intervals, and the temperature change is calculated. Is less than or equal to a predetermined value, the output of the defrosting heater is increased, and when the temperature change exceeds a predetermined value, the output of the defrosting heater is decreased so that the electric refrigerator is controlled. 2. The electric refrigerator according to claim 1, wherein the output of the defrosting heater is controlled in multiple stages corresponding to the temperature change rate of the evaporator.