JPS6029573A - Controller for defrostation of refrigerator, etc. - 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 Field of the Invention The present invention relates to a defrosting control device that optically detects frost adhering to a cooler such as a refrigerator and issues a defrosting command.

Conventional Structure and Problems Generally, this type of defrosting control device is constructed by disposing a frost detector in a cooling chamber in which a cooler is installed in order to detect the amount of frost on the cooler. The frost amount detector is equipped with a light-emitting element and a light-receiving element inside a transparent case, which are opposed to each other through a frost detection hole in a cooler plate, which serves as a frost formation plate. The amount of frost is detected by detecting changes in the amount of light passing through the hole as frost formation progresses. However, conventional defrosting control devices continue to be energized regardless of whether the door is open or closed, so when the door opens, outside air, which is hotter and more humid than the inside (cooling room) atmosphere, flows in, so it is placed in the cooling room. The surface of the frost detector case, which is at the bottom temperature, becomes cloudy and the amount of light passing from the light emitting element to the light receiving element is blocked, causing the defrosting operation to start even though the cooler has not yet become frosted. This has been a major drawback of optical defrost detection devices.

In order to solve this drawback, it is possible to disable the defrost operation when the door is opened, but even if the defrost operation is simply disabled while the door is open, the frost detector will fog up immediately after the door is closed. There was no way to release it, and there was a problem with malfunctions.

Purpose of the Invention Page 3 Therefore, the present invention aims to eliminate the instability of the defrosting operation caused by the fogging of the surface of the frost detector, that is, the instability of the operation caused by opening and closing of the door, and to defrost reliably and always at the optimum defrosting detection point. The purpose is to provide a defrosting control device that can

Structure of the Invention In order to achieve this object, the present invention maintains the defrost control circuit inoperable for a certain period of time while the door is open, through which outside air flows in, which causes fogging on the surface of the frost detector case, and for a certain period of time after the door is closed. This prevents false detection by stopping defrost detection.

Description of examples An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a refrigerator (cooling chamber A of a refrigerator) equipped with a defrosting control device according to an embodiment of the present invention.

In this figure, reference numeral 1 denotes a cooler consisting of fins 2 and refrigerant pipes 4 passing through end plates 3 on both sides of the fins 2, and constitutes a well-known refrigeration cycle with a compressor 13, which will be described later. 5 is a fan motor for forcibly circulating air through the cooler 1, and 6 is a frost detector attached to a part of the end plate 3.

The cooler 1 is provided with a cooler defrosting heater 11, which will be described later.

The frost detector 6 will be explained in detail in FIG. frost detector 6
A light emitting element 6a and a light receiving element 6b are provided inside a transparent case 6C, which face each other through a small frost detection hole 3b provided in a notch 3a of the end plate 3 of the cooler 1 as a frost forming plate, The amount of frost is detected by detecting changes in the amount of light passing through the small holes 3b as frosting progresses. In addition,
6d is a lead wire 6e for external wiring, which is a mounting board for the light emitting element 6a and the light receiving element 6b.

When the temperature drops below a predetermined temperature, the circuit opens. 9 is the removal ζ° which will be described later.

Signal from the frost control circuit 1o: A heater 11 for defrosting the cooler and a bimetal thermostat 12 for detecting the end of defrosting are connected in series to the normally open contact 9a which is the first relay to be switched.
The normally closed contact 9b is connected in series to the compressor 13, and the transfer door switch 14 is connected in parallel with the compressor 13, and the closed contact 14a, which closes when the door is closed, is connected to the cold air in the refrigerator. A coil 15a of a second relay 16 that stops energizing the frost detection device 10, which will be described later, is connected to the stirring fan motor 5 and the opening contact 14b that closes when the door is opened, and the coil 15a An OFF delay element 16 is connected in parallel with the OFF delay element 16, and the second
The deenergization of relay 16 is delayed for a certain period of time.

Next, the defrosting control circuit 1o will be described. 17 is a power transformer, 18 is a rectifying diode, 19 is a smoothing capacitor, and 2o is a constant voltage diode, which constitutes a DC constant voltage circuit, and a part of the coil 17a of the power transformer 17
is connected in series to the alternating current power supply 7 together with the normally closed switch 16b of the second relay 15 and the internal temperature regulator 8. Reference numeral 21 denotes a current limiting resistor for the light emitting element -tea of the frost detector 6, which is connected in series with the light emitting element 6a to the DC constant voltage circuit. 22 is the light receiving element 6b of the frost detector 6
The frost detector output voltage 22a and resistance 2 are determined by the amount of light received.
3.25 is a comparator that compares the voltage with a reference voltage 22b determined by 24, and 25 receives the defrosting start signal which is the output 22c of the comparator 22 as S input, and detects the end of defrosting by detecting the opening of the contact of the bimetal thermometer 12. This is an SR flip-flop circuit whose state changes using the output signal of the circuit 26 as an R input, and 27 is a transistor that drives the first relay 9 with the output 25c of the SR flip-flop circuit.

The operation in the above configuration will be explained. When the frost on the cooler 1 progresses and the frost detection small holes 3b are blocked by the frost, the amount of light received by the light receiving element 6b decreases, and as a result, the frost detection type output voltage 22a decreases, and the reference voltage of the comparator 22 2
2b, a defrosting start signal is inputted from the comparator 22 to the SR flip-flop circuit 26, and the set state is established, the transistor 27 is turned on, and the first relay 9 is turned on.
is closed. That is, the normally closed contact 9b opens and the normally open contact 9a closes to disconnect the compressor 13 and fan motor 6 from the AC power source 7, stop the cooling operation, and connect the cooler defrosting heater 11 to the power source. Then, when the temperature of the cooler 1 rises and becomes equal to or higher than the set value of the bimetal thermostat 12, the bimetal thermostat 12 is opened and defrosting ends.

At the same time, a defrost end signal is inputted to the SR flip-flop circuit 26 from the defrost end detection circuit 26 that detects the opening of the contact of the bimetal thermometer 12, and the SR flip-flop circuit 26 enters a reset state.
The first relay 9 is deenergized, its normally open contact 9a opens and its normally closed contact 9b closes. That is, compressor 13. The fan motor 6 is connected to the power supply again and starts cooling operation.

On the other hand, when the door opens in this cooling operation state, the closing contact of the door switch 14 switches, and at the same time as the fan motor 6 stops, the second relay 15 is energized and the switch 1
6b, a part of the coil 17& of the power transformer 17 is opened, and energization to the defrosting control circuit 10 and the first relay 9 is stopped, making defrosting detection impossible. Next, when the door is closed, the closing contact of the door switch 14 is switched and the fan motor 6 is energized, but the second relay 16 continues to be energized for a certain period of time by the OFF delay element 16. During this time, defrost cannot be detected.

Therefore, even when the door is opened, outside air flows in and the surface of the case 60 of the frost detector 6 becomes cloudy, and the amount of light passing from the light emitting element 6a to the light receiving element 6b temporarily decreases, the defrost control circuit 1o and the first relay 9 did not operate, and the undetectable state continued until the fog disappeared after the door was closed, thereby preventing malfunction (defrosting start) due to fog. Note that during the defrosting operation, the defrosting control circuit 10 and the first relay 9 are constantly energized regardless of whether the door is opened or closed, so that the bimetal thermostat 12 can perform stable defrosting until the cooler defrosting is completed.

Effects of the Invention As is clear from the above explanation, the present invention has a cooler,
The cooling chamber in which this cooler is placed includes a frost detector that optically detects the amount of frost on the cooler, a defrost control circuit that performs defrosting operation based on the output signal from the frost detector, and a defrost control circuit that controls the opening of the door. 9 days after the door is closed, the surface of the case of the frost detector becomes cloudy due to the inflow of outside air which is hotter and more humid than the atmosphere inside the refrigerator. Even if the amount of light passing from the light-emitting element to the light-receiving element decreases, defrosting is not started, which is reliable, and has the effect that defrosting operation can always be performed at the optimum amount of frost.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a cooler equipped with a defrost control device according to an embodiment of the present invention, Fig. 2 is a partial sectional view of a frost detector of the same device, and Fig. 3 is an electric circuit diagram of the same device. be. 6...Frost detector, 10...Defrost control circuit, 14...Door switch, 16...
OFF delay element (means). Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
[! 1 Figure 2

Claims (1)

[Claims] a cooler, a frost detector provided in a cooling chamber in which the cooler is placed and optically detects the amount of frost on the cooler, and a defrosting control circuit that performs a defrosting operation based on an output signal from the frost detector. ,
A defrosting control device for a refrigerator or the like, comprising a door switch that detects door opening and deactivates the defrosting control circuit, and means for continuing the deactivation of the defrosting control circuit for a predetermined period of time after the door is closed.