JPS60274A - Defrostation control circuit for cooler - 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 The present invention provides a cooler that detects frost adhering to the cooler by attaching a frost detector having a vibrating surface to which a piezoelectric vibrator is attached to a cooler such as a refrigerator and issues a defrosting command. The present invention relates to a defrosting control circuit.

Conventionally, in the defrost control circuit of this type of cooler, when the power is turned off during normal cooling operation and then turned on again (generally during power outages), the defrosting operation does not start again due to the amount of frost. There was a problem with doing this. That is, this frost detection device is composed of a piezoelectric vibrator and an oscillation circuit, and as frost progresses on the vibrating surface of the frost detector, which has a vibrating surface on which the piezoelectric vibrator is pasted, vibrations are suppressed. The vibration stops and defrosting begins when the amount of frost builds up to a certain level, and normally it oscillates at a certain frequency and the vibrating surface vibrates. However, when the power is turned off and then turned on again, if there is little frost on the frost detector, the oscillation will easily return, but if there is a lot of frost on the frost detector, the vibration will be suppressed and oscillation will occur. It did not recover and issued a defrost command.

An object of the present invention is to provide a defrosting control circuit for a cooler that eliminates the above-mentioned drawbacks.

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

In the figure, reference numeral 1 denotes a frost detector, which includes a metal casing 2 with good thermal conductivity and a piezoelectric vibrator 4 attached to a vibrating surface 3 integrally formed with the casing 20 via an elastic part 2a.
This is similar to the heater 5 that removes frost that adheres to the vibrating surface during defrosting. In addition, 6 is a molding material such as epoxy resin for fixing the heater 6, and 7 is an airtight plate that airtightly separates the vibrating part of the piezoelectric vibrator 4 from the molded part of the lower heater 6. 8 is a lead wire of the heater 5, and 9 is a lead wire of the piezoelectric vibrator 4.

Reference numeral 10 denotes a cooler consisting of a large number of cooling fins 11 and cooling pipes 12 orthogonal to the fins, and 13 is a fan motor for forcing air through the cooler 10. 14 is cooler 1
The frost detector 1 is attached to the end plate of 0.

Next, the electric circuit will be explained. Reference numeral 16 denotes an oscillation circuit connected to the piezoelectric vibrator 4, which causes the piezoelectric vibrator 4 to oscillate at a certain oscillation frequency.

Reference numeral 16 denotes an ON delay timer connected to the power supply line in parallel with the oscillation circuit 16. 17 is the timer 1
This impedance element is connected in parallel with the piezoelectric vibrator 4 through the normally open contact T1 of 6, and is used to lower the oscillation level to an appropriate level.

18 is a defrosting heater used in cooler 1o,
The piezoelectric vibrator 4 is connected in parallel with the heater 5 of the frost detector 1, and the vibration of the piezoelectric vibrator 4 is suppressed due to frost formation. It is connected to the power supply via the normally open contact R2 of relay R, which is energized and operated by the signal of It is connected to a power source via a closing contact R1 and a thermostat 20 for regulating the temperature inside the refrigerator.

In such a device, during normal cooling operation, the contact of the timer 16 is on the normally open contact T1 side, and the impedance element 17 is connected in parallel with the piezoelectric vibrator 4, reducing the oscillation level to an appropriate level. When a certain amount of frost adheres to the detector 1, the weight of the frost suppresses the vibration of the piezoelectric vibrator 4, and the oscillation of the oscillation circuit 15 stops (when the oscillation level is below a predetermined value).

Then, this oscillation circuit energizes the relay R, closes the normally open contact R2, energizes the defrosting heater 18 and the heater 6 of the frost detector 1, and stops the electric compressor 19 to defrost the cooler 10. will be done.

When defrosting is completed, the frost detector 1 returns to oscillation, and the oscillation circuit 16 cuts off the power to the relay R, and the normally closed contact R1 closes, causing the electric compressor 19 to operate and restarting the cooling operation.

Here, if the power is cut off for some reason during cooling operation,
The contacts of the timer 16 are from normally open contact T1 to normally closed contact T.
Move to the 2nd side. After that, when the power is turned on, the ON delay timer 16 operates and the contact remains on the normally closed contact T2 side until a preset time has elapsed, and when the set time is reached, the normally open contact T1
Move to the side. Therefore, when the frost detector 1 has a certain amount of frost and the vibration is suppressed to a certain extent, the power is turned off, and when the power is turned on again, the impedance element 17 that lowers the oscillation level of the piezoelectric vibrator 4 is kept constant by the action of the timer 16. Since the timer is cut off, even if the oscillation level increases and vibrations are suppressed due to frost formation, the oscillation is easily restored, and malfunctions as in the conventional example do not occur. When the set time has elapsed, the contact of the timer 16 moves to the normally open contact T1 side, and the impedance element 17 is connected in parallel with the piezoelectric vibration -74, so that the oscillation level is lowered and proper detection is performed.

As described above, the present invention includes a frost detector having a piezoelectric vibrator, an oscillation circuit that vibrates the piezoelectric vibrator, an impedance element that changes the oscillation frequency of this circuit, and a frost detector that vibrates the piezoelectric vibrator. This device is equipped with a timer that eliminates the effect on the oscillation circuit, and when the power is turned on after a power outage due to some reason during cooling operation, the timer is used to suppress vibrations due to frost buildup on the frost detector for a certain period of time. By raising the oscillation level by only 1, the oscillation can be easily restored and the cooling operation can be started normally.This is highly effective in practical use because defrosting can be reliably controlled without accidentally entering defrosting.

[Brief Description of the Drawings] Fig. 1 is a plan view of a cooler equipped with a defrost control circuit according to an embodiment of the present invention, Fig. 2 is a sectional view of a frost detector of the same circuit, and Fig. 3 is a sectional view of the same circuit. FIG. 2 is a schematic electrical circuit diagram. 1...Frost detector, 4...Piezoelectric vibrator,
15...Oscillation circuit, 16...Timer, 1
7... Impedance element. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
-Figure 13 Figure 2 Figure 3 0

Claims (1)

[Claims] A frost detector having a piezoelectric vibrator, an oscillation circuit that vibrates the piezoelectric vibrator, an impedance element that changes the oscillation frequency of this oscillation circuit, and removing the effect of the impedance element on the oscillation circuit for a predetermined period of time when power is re-energized. A defrosting control circuit for a cooler comprising a timer.