JPS608686A - Controller for defrostation - 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 Industrial Application The present invention relates to a defrosting control device for refrigerators, etc., and in particular to a defrosting control device for a refrigerator, etc., which detects frost adhering to a cooler using a piezoelectric frost detector. The present invention relates to a defrost control device that controls a defrost heater and a defrost heater for a frost detector provided in a frost detector.

Conventional horizontal plates and their problems In general, frost detectors with a built-in piezoelectric element for frost detection have a built-in defrost heater for the frost detector, which simultaneously removes frost adhering to the frost detector when the cooler is defrosted. Conventionally, the energization time of the defrost heater was controlled in synchronization with the energization time of the defrost heater for the cooler.

For example, as shown in Fig. 1 as a conventional example, a defrost heater a for a cooler and a defrost heater b for a frost detector are connected in parallel, and a relay C that switches between cooling operation and defrost operation senses the temperature of the cooler and connects the contacts. A bimetal thermometer d that opens, and a photocoupler e for detecting the end of defrost, which receives and receives signals by opening the contacts of the thermometer d.
The defrost heaters a and b are simultaneously controlled by a frost detection circuit f which uses a frost detector and issues a defrost start command from the frost detector and a defrost end command from the above-mentioned photocoupler 〇 to operate relay C. It is. However, in this structure, the amount of heat generated by the defrost heater b for the frost detector is set so that the frost detector is almost completely dry at the end of defrosting. Even if defrosting is completed, the defrosting of the cooler is not completed, that is, the bimetal thermometer d cannot sense the temperature and the defrosting completion signal is not issued, so the energization time of both defrost heaters a and b becomes longer.
There has been a problem in that the frost detection piezoelectric element in the frost detector is greatly affected by heat, causing characteristic deterioration.

Purpose of the Invention Therefore, the present invention provides a defrost control device having a frost detector with a built-in defrost heater for the frost detector. The purpose is to prevent property deterioration due to heat.

Structure of the Invention In order to achieve this object, the present invention includes a defrost detection circuit that detects the end of defrosting of a frost detector, and an energization control circuit that controls the amount of energization of a defrost heater for a cooler. Control is performed so that the amount of electricity applied to the frost detector is reduced after defrosting, thereby preventing characteristic deterioration of the piezoelectric element.

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

FIG. 2 shows a frost detector 1 according to an embodiment of the present invention.

2 is a metal casing with good thermal conductivity; 3 is a vibrating section having a piezoelectric element 4 attached to the inner surface of the casing 2; 5 is a defrost heater for a frost detector that removes frost adhering to the vibrating surface 3 during defrosting; 6 is a molding material such as Evogishi resin that is packed into the metal casing 2 and fixes the heater 5;
Reference numeral 7 denotes an airtight plate that airtightly separates the vibrating part where the piezoelectric element 4 is located and the molded part of the lower heater 6. 8 is a lead wire of the piezoelectric element 4 and the heater 5. This frost detector 1 is used, for example, in a forced air cooler of a refrigerator (
(not shown), and the vibrating part 3 is frosted together with the cooler.

Next, as shown in FIG. 3, the defrost control circuit according to the embodiment of the present invention includes a relay R1 for switching between cooling operation and defrost operation, and a defrost heater 8 for the cooler disposed in the cooler.
1. A defrost heater 5 for a frost detector, a relay R2 that turns on and off the heater 5, a defrost detection circuit C1 that senses the amount of heat generated from the heater 5 and controls the contacts of the relay R2, and a frost detector. 1, a frost detection circuit C2 detects frost formation therein and controls the contact of the relay R1; an energization control circuit C3 controls the amount of electricity supplied to the cooler defrost heater h1 based on a signal from the control circuit C1; It is composed of a bimetal thermostat (1) which detects the completion of energization of the defrost heater H1 for the cooler, that is, detects a rise in temperature of the cooler, and a photocoupler P which transmits a signal of the completion of energization from the bimetal thermometer to the frost detection circuit C2. That is, the defrosting contact D1 of the relay R1 is connected to the energization control circuit C3.
is connected to one end of the heater H1 and the common contact of the relay R2, and the contact D3 is connected to the negative terminal of the compressor, etc.
It is connected to the. The other end of the heater H1 is connected to a bimetal thermostat 1 and a photocoupler P. The frost detection heater 5 is connected to the contact D2 for removing ff'[1 of the relay R2.
and connected to power.

A defrost detection circuit C1 that detects the amount of heat generated by the heater 5 and controls the relay R2 is connected to the relay R2 and the frost detection circuit C2, and the frost detection circuit C2 is connected to the relay R1, the defrost detection circuit C1, and the photocoupler P. The input terminal of the photocoupler P is connected to the bimetal thermostat ■1.

FIG. 4 shows details of the energization control circuit C3, including a bidirectional control element TRA1 for controlling the amount of energization to the denolost heater H1 for the cooler, a gate current limiting resistor RE1 of the bidirectional control element TI (A1), and a resistor RE1 for limiting the gate current of the bidirectional control element TI (A1). Tropical control element TRA1
a gate current control transistor TH1, and a relay R3 for switching the state of the base current of the transistor TFz.
,] a pulse oscillator PA1, and a gate current limiting resistor RE2 of the transistor TR1. Regarding the connection state of these components, the bidirectional control element TRA1 is connected to the relay R1 and the cooling defrost heater FL1, and its gate terminal is connected to one end of the resistor RE1. The other end of the resistor RE1 is connected to the collector terminal C of the transistor T)11.

The emitter terminal of transistor TR1 is grounded,
The base terminal is connected to the common contact of relay R3.

The resistor tE2 is connected to the circuit power supply and the switching contact of the relay R3.

The other switching contact of relay R3 is connected to pulse oscillator Pc1, and further connected to defrost detection circuit C1 for contact control.

Next, the operation of the above configuration will be explained. Frost detection circuit C2
When a predetermined amount of frost is formed on the frost detector 1, that is, the cooler, a frost signal is output, and the signal is input to the relay R1 and the control circuit C1. Then relay R1
In this case, the contact piece is inclined toward the defrosting contact D1 side, and the heater H1 is energized. Furthermore, upon receiving the defrost signal, the defrost detection circuit C1 tilts the contact piece of the relay R2 toward the defrosting contact D2, and the heater 5 is energized. Next, when the frost on the frost detector 1 is removed by the defrost heater 5 for the frost detector and the amount of heat generated from the frost detector 1 increases, the defrost detection circuit C1 detects this and the defrost starts. When the amount of heat generated at the time of completion is reached, a defrost end signal for the frost detector 1 is outputted from the defrosting detection circuit C1, the contact piece of the relay R2 is switched, and the energization of the defrost heater 6 for the frost detector is stopped. Further, the frost detector defrost end signal is also input to the energization control circuit C3 of the 6-cooler defrost heater H1. Now, the defrosting of the frost detector 1 has been completed and the power supply has been stopped, but the defrosting of the cooler has not yet been completed. When the frost detector defrost end signal is input to the energization control circuit C3, the contact point of the relay R3 is switched from the resistor RE2 side to the pulse oscillator P side to the 1 side. Then, the current waveform (Fig. 5a) that has been flowing through the cooler defrost heater H1 until now is changed to the current waveform flowing through the cooler defrost heater H1.
1 is switched in accordance with the output of the pulse oscillator PA1 (Fig. 6b), resulting in a half-wave rectified waveform as shown in Fig. 6C. It becomes half. Therefore, the amount of heat generated is reduced accordingly, and the effect of heat on the piezoelectric element 4 is prevented.

Next, when the end of defrosting of the cooler is detected by the bimetal thermostat v1, the contact of the bimetal thermostat v1 is opened, a detection signal is input to the photocoupler P, and the detection signal is input to the frost detection circuit C2. Upon receiving the defrost end signal, the frost detection circuit C2 switches the contact of the relay R1 to the cooling side contact P3, and switches to driving a load such as a compressor, thereby completing the defrost operation.

Effects of the Invention As is clear from the above explanation, according to the present invention, the amount of electricity supplied to the defrost heater for the cooler is changed after the defrosting of the frost detector is completed.
By decreasing the temperature, the temperature of the cooler can be lowered by 4, and the thermal influence on the piezoelectric element for frost detection built in the frost detector can be reduced.

[Brief explanation of the drawing]

Figure 1 is a defrost heater control circuit diagram of a conventional piezoelectric frost detector, Figure 2 is a sectional view of the frost detector, Figure 3 is a defrost control circuit diagram of an embodiment of the present invention, and Figure 4 is energization. The control circuit diagram, FIG. 6, shows a current waveform diagram supplied to the defrost heater for the cooler. 1...Frost detector, 4...Piezoelectric element, 5
...Defrost heater for frost detector, 1111...
...Defrost heater for cooler, C1...Defrost detection circuit, C2...Frost detection circuit, C3...
Energization control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Figure 4

Claims (1)

[Claims] A defrost heater for a cooler that defrosts the cooler, and a piezoelectric element that vibrates a vibrating surface on which frost is attached. A frost detector having a built-in defrost heater for defrosting the vibrating surface, a frost detection circuit having the frost detector and switching between defrosting operation and cooling operation, and a defrost heater for the frost detector. a defrost detection circuit that detects the completion of defrosting by detecting the amount of heat generated by the frost detector; and an energization control circuit that controls the amount of electricity supplied to the defrost heater for the cooler to be reduced after the defrost detection circuit detects the completion of defrosting. Defrost running control device with fl+IJ control circuit and back circuit.