JPS60165483A - 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 a box attached 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 detector is equipped with a light emitting element and a light receiving element facing each other through a frost detection hole in a cooler plate serving as a frost formation plate, and the amount of light passing through the frost detection hole when frost has progressed. The amount of frost is detected by detecting changes in the amount of frost.

However, in conventional defrosting control devices, if the light emitting element or light receiving element fails, the amount of transmitted light disappears or the transmitted light becomes unable to be detected, and the signal output from the frost detector indicates the frost formation state of the cooler. Since it is a 1N signal regardless of whether or not the defrost is in operation, the defrost heater is continuously energized and the temperature inside the refrigerator continues to rise.
This has been a major drawback of optical defrost detection devices, since not only the stored food may be damaged, but also an unsafe condition such as a fire may occur. To deal with this,
In other words, as a countermeasure against element failure, the relationship between the element state and the operation mode is determined for a certain period of time T(
It is considered that defrosting should be performed at regular intervals (when frost builds up on the cooler and defrosting is required), but if the element failure occurs immediately before defrosting is applied, a considerable amount of frosting may occur at that point. Since frost had already been reached, if the cooling operation was continued for a predetermined period of time from that point on, there was a risk that excessive frost would form and the fan etc. would freeze.

Purpose of the Invention Therefore, the present invention eliminates the continuous defrosting operation due to a failure of the light emitting element and light receiving element of the frost detector, and defrosts at regular intervals to continue the cooling operation, thereby preventing the temperature rise inside the refrigerator. In addition, it is an object of the present invention to provide a defrosting control device that can ensure the safety of stored items and equipment by preventing excessive frosting by performing early defrosting only immediately after a failure.

Structure of the Invention In order to achieve this object, the present invention detects an abnormality in a frost detector, detects a failure in a light emitting element, a light receiving element, etc. of the frost detector, and disables the defrosting operation by a defrosting control circuit. While maintaining the cooling operation, after this failure, the cooling operation time will be reset every time the cooling operation time reaches a certain time, and especially immediately after the failure, the cumulative time before starting the defrosting operation will be shorter than usual to prevent the failure. By eliminating the phenomenon of excessive frosting that occurs immediately after defrosting is not applied for a long period of time, the function of the equipment can be maintained, and the safety of the stored items and the equipment can be ensured.

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

Figure 2 D1. Akira Kimoto - FIG. 2 is a plan view of a refrigerator (cooling chamber A for chilled rhinoceroses) equipped with a defrosting control device according to an embodiment.

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 an electric compressor 12, which will be described later. Reference numeral 6 represents a fan motor for forcibly circulating air through the cooler 1, and 6 represents a frost detector attached to a portion of the end plate 3.

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

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 facing each other are housed in a case 6C through a frost detection small hole 3b provided in a cutout 3a of the end plate 3 of the cooler 1 as a frost forming plate. The amount of females is detected by detecting the change in the amount of passing light as the frosting of 3b progresses.

Next, an electric circuit as a defrosting control device will be explained with reference to FIG. Reference numeral 7 denotes a commercial AC power source, and 8 indicates an internal temperature regulator which opens when the internal temperature falls below a predetermined temperature.

9 is a relay that is switched by a signal from a defrosting control circuit 1o, which will be described later.The normally open contact 9aVC is connected in series with the defrosting heater 11 of the cooler 1, and the normally closed contact 9b is connected with the electric compressor 12. are connected in series, and the aforementioned fan motor 6 is further connected in parallel with the compressor 12.

Next, the defrosting control circuit 10 will be described. 13 is a power transformer, 14 is a rectifier diode, and 16 is a constant voltage diode, which constitute a DC constant voltage circuit. 16 is a current limiting resistor for the light emitting element 6a of the frost detector 6;
A is connected in series with the DC constant voltage circuit. 17
is a frost detection combo signal, and the frost detection word output a determined by the amount of light received by the light receiving element 6b of the frost detector 6 is input to the inverting input terminal 17a, and the voltage divided by the series combined resistance of resistor 18 and resistor 19.20 is input to the inverting input terminal 17a. The defrosting start setting voltage determined by is connected to each non-inverting input terminal 17b, the frost detection word output a and the defrosting starting setting voltage are compared, and an output signal is outputted from the output terminal 17c. A feedback resistor JfL21 is provided between the output terminal 17c and the non-inverting input terminal 17b. 22 is a failure detector (comparator), and the frost detector output a
is connected to the non-inverting input terminal 22a, and the abnormality detection setting voltage determined by the divided voltage yc of the series composite resistor 20 of resistors 18 and 19 is connected to the inverting input terminal 22b, and the frost detection word output a and the abnormality detection voltage are compared. The output signal is output from the output terminal 22c. Note that the abnormality detection voltage is set to a voltage sufficiently lower than the defrosting start voltage and at a very low voltage that can detect a failure of the light emitting element 6a and the light receiving element eb.

23 is the output terminal 17C of the frost detection comparator 17
24 is an AND gate that performs a logical AND operation on the signal of 1 and the signal of the output terminal 22c of the failure detector 22, and 24 is a transistor that drives the relay 9 with the output 23a of the AND gate 23. 26 is a timer switch, which connects the output 22c of the fault detector 22 to its timer motor 26a via the inverter 26, and
It is energized and operates only when a failure signal (“L” level) is output from 2, and for the first time it operates only T/2 for the standard time T when frost builds up on the cooler and defrost is required. Then, the switch 25b is closed only for the time required for defrosting.
Further, from the second time onward, each time the defrosting operation is performed for the standard time T, the defrosting operation is closed. (In this embodiment, the timer switch 26 is installed in the device in a state in which the timer motor 25a is integrated by T/2.) Note that the switch 26b of the timer switch 25 is operated as described above regardless of the operation of the transistor 24. It is connected in series with the coil 9C to drive the relay 9.

The operation of the above configuration will be explained with reference to the graph of FIG. 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 debris detector output voltage a decreases and the frost detection comparator 17 When the voltage drops below the defrosting start voltage, a frost detection signal (“H” level) is input from the output terminal 17c of the frost detection comparator 17 to the AND gate 23.

At this time, if the light-emitting element 6a and the light-receiving element 6b are not faulty, the detector output a is higher than the abnormality detection voltage and no fault signal ("L" level) is output from the output terminal 22c of the fault detector 22. The normal signals r and i at "H" level are input to the AND gate 23, while the timer motor 25a of the timer switch 25 is not energized and the timer switch 26b is open.

Therefore, the frost detection signal (
When the AND gate 23 is energized, a defrosting start signal (aH level) is output from its output terminal 23a, the transistor 24 is turned on, and the relay 9 is activated. That is, the normally closed contact 9b opens and the normally open contact 9a opens.
is closed and the electric compressor 12 is connected to the AC power source 7. The fan motor 6 is disconnected to stop the cooling operation, and the cooler defrosting heater 11 is connected to the power source. When the defrosting of the cooler 1 progresses and the frost blocking the frost detection small holes 3b disappears, the output a of the frost detector 6 increases, and the differential voltage by the feedback resistor 21 of the frost detection comparator 17 increases. When the voltage becomes higher than the defrosting start voltage plus the defrosting start voltage, the frosting signal ("H"
' level) is no longer output, and as a result, the output of the AND gate 23 becomes a defrosting prohibition signal ('L' level), the transistor 24 becomes non-conductive, the relay 9 is deenergized, and the electric compressor 12 and fan motor 6 are turned on again. Connect to power supply and start operation.

On the other hand, if a failure occurs such as the light emitting element 6a stopping emitting light or the light receiving sensitivity decreasing of the light receiving element 6b (Fig. 5P), the frost detector 6
The output a of the output terminal 22c decreases significantly and falls below the abnormality detection voltage, which is the reference voltage of the failure detector 22.
A failure signal (L” level) is output from AND gate 2.
The output of No. 3 becomes a defrosting prohibition signal regardless of the output of No. 11, and the output of No. 3 becomes a defrosting prohibition signal regardless of the output of No. 17. From then on, the transistor 24 becomes non-conducting. Signal (“L#
level) is output, it is activated by the operation of the inverter 26, and the timer switch 2ts is activated every preset time (immediately after the failure, standard time T bar, thereafter standard time T constant).
b opens and closes to operate the relay 9, and even after a failure occurs, cooling operation is continued while defrosting operation is performed at regular intervals.

As is clear from the text, frost detector failures are due to deterioration of built-in elements or internal disconnections, and once a failure occurs, it cannot be automatically corrected; therefore, it continues to operate as a timer type.

Therefore, when the light-emitting element 6a or the light-receiving element 6b breaks down, the problem that the defrosting operation is started regardless of whether or not there is frost on the cooler 1, and the defrosting heater 11 is continuously energized and the temperature inside the refrigerator rises abnormally is eliminated. By performing early defrosting for the first time even after an element failure occurs, it is possible to prevent excessive frost from forming on the cooler even if the failure occurs just before the defrosting is turned on.This prevents freezing of the fan, etc. Defrost operation is performed every time the accumulated cooling operation time reaches the standard time when frost builds up on the cooler and defrost is required, ensuring the safety of stored items and equipment. can.

Moreover, in this embodiment, there is no need to preliminarily provide a light emitting element 6a and a light receiving element 6b, which were required in the conventional failure detection method, and the failure can be detected using a simple circuit and a few additional parts by using the output of the frost detector 6. It is highly practical as it can also ensure the security of stored goods and equipment.

Effects of the Invention As is clear from the above description, the present invention includes 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 frost detector that detects the amount of frost on the cooler. a defrosting control circuit that performs a defrosting operation based on an output signal from the defrosting control circuit; a failure detector that detects an abnormality in the output signal and prohibits the defrosting operation from being started when the defrosting control circuit VC is interrupted; and an operation of the failure detector. and a defrosting control means that operates in conjunction with the defrosting control circuit and independently of the defrosting control circuit and performs the defrosting operation every time the cooling operation is accumulated for a certain period of time, and the former defrosting control means is operated only immediately after the failure detector is activated. Since the defrosting input timing is set earlier than the above-mentioned fixed time, the frost detector's ability to normally detect frost formation can be detected by malfunctions such as a significant drop in the amount of light emitted by the light-emitting element of the frost detector, or a decrease in the light-receiving sensitivity of the light-receiving element. Abnormal values can be detected reliably and easily (at low cost), and unlike conventional methods, defrosting operation is turned on regardless of whether frost has formed on the cooler, and the defrosting heater is continuously energized, causing an abnormal rise in temperature inside the refrigerator. The problem of doing so disappears. In addition, by performing early defrosting for the first time even after an element failure occurs, it is possible to prevent excessive frost from forming on the cooler, even if the failure occurs just before the defrosting is turned on, and to prevent freezing of the fan, etc. Since cooling operation is continued while defrosting operation is performed every time the cumulative cooling operation time becomes constant, the safety of stored items and furthermore the safety of equipment is greatly improved, and the practical effects are extremely large.

[Brief explanation of the drawing]

Fig. 1 is a time chart showing the operation of a conventional defrosting control device, Fig. 2 is a plan view of a cooler equipped with a defrosting control device according to an embodiment of the present invention, and Fig. 3 is a frost detector of the same device. FIG. 4 is an electric circuit diagram of the device, and FIG. 6 is a time chart showing the operation of the device. 6... Frost detector, 10... Defrost control circuit, 22... Failure detector, 26... Timer switch (defrosting control means). Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
11

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 defrost control circuit that performs a defrosting operation based on an output signal from the frost detector; a failure detector that detects an abnormality in the output signal and prohibits the defrosting control circuit from starting a defrosting operation; and a cooling operation that is linked to the operation of the failure detector and is independent of the defrosting control circuit. A defrosting control device for a refrigerator or the like, comprising a defrosting control means that performs a defrosting operation every time a predetermined period of time is accumulated, and in which the defrosting input timing by the pre-defrosting 111 control means is brought forward only immediately after the failure detector is activated.