JPS5815819A - Controller of electric cooker - 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 is an electric cooker such as an electric pressure cooker or an electric deep fryer that has a temperature control circuit made of electronic components built into the main body, and which suppresses the temperature rise of the main body itself as much as possible. This invention relates to a control device designed to protect electronic components and mechanical components.

Conventional electric cookers have either been large in size or have a small power capacity in order to keep the temperature rise of the main unit to a low level. Therefore, there have been cases where costs have increased and sufficient cooking performance has not been obtained. However, the rise time from the start of temperature rise until reaching the cooking temperature should be as short as possible, and for example, in a deep fryer, etc., it is better to
Since it is necessary to quickly restore the cooking performance, the power capacity of the electric heating element is generally increased in order to ensure such cooking performance. On the other hand, if an attempt is made to make the main body as compact as possible, the temperature of the main body itself increases during use, and the influence on electronic components and mechanical components increases, resulting in a significant decrease in reliability.

By the way, when examining the temperature rise of the main body itself, it is found that the rise in temperature of the main body itself is greatest when water is poured into a cooking container and kept at a boiling state continuously. For example, in the case of the above-mentioned deep fryer, 10/
If the electrical capacity of the heating element is set to be as large as 1.2 kW for the oil capacity of , the temperature environment of the parts becomes harsh. When the control temperature is reached during normal use and control is started, the heating element enters the control area, so the temperature rise in each part of the main body is small even though the temperature inside the container is high. In addition, when water is boiling, power is consumed as heat of evaporation, so it is better to reduce the power consumption in terms of energy conservation.

The present invention has been made in view of the above points. - When the temperature inside the container (that is, the contents) reaches a temperature slightly lower than the boiling point of water, the power is temporarily lowered, and the contents of the container are If it is water, the boiling state will be maintained while the power is reduced, and if the load is tempura oil or a pressure cooker, the temperature of the contents of the container will exceed the boiling point of water, and the temperature will be slightly higher than the boiling point of water and controlled. An electric cooker that returns the power to its original value when the temperature reaches a lower temperature, minimizing the temperature rise of the main unit itself and improving the reliability of electronic and mechanical parts. The present invention provides a control device for the following. Below 1
, 1 will be described in detail with reference to the drawings.

FIG. 1 shows the electrical configuration of one embodiment of the present invention, and is an example applied to a household electric deep fryer. In FIG. 1, 1 is an AC power supply, 2 is a temperature fuse, 3 is an electric heating element, 4 is a power switch, 5 is a power control element (TRIAC), 6 is a cooking container, 7 is a heat-sensitive sensor (negative characteristic thermistor), 8 is a power supply circuit which generates a zero-phase signal in addition to DC. 9 is an ignition circuit for the power control element 5; 10 is a detection circuit for detecting a first temperature slightly lower than the boiling point of water; and 11 is a detection circuit for detecting a second temperature slightly higher than the boiling point of water and lower than the control temperature. The circuit 12 is an inhibit circuit that controls the ignition circuit 9 to reduce the power between the first temperature and the second temperature, and the numeral 13 is a temperature control circuit.

This embodiment is an electric deep fryer, and when a container 6 is filled with frying oil and electricity is applied, the oil temperature gradually rises, and this temperature is detected by a heat-sensitive sensor 7. When the first temperature, which is slightly lower than the boiling point of hot oil and water, is reached, the detection circuit 10 outputs an output, and this output is input to the inhibition circuit 12.
A part of the ignition signal of the ignition circuit 9 is inhibited by the output of the inhibition circuit 12, and the power applied to the heating element 3 is reduced. but,
Even if the electric power decreases, the oil temperature in the container 6 rises and reaches the second temperature. At this time, an output is generated in the detection circuit 11, and this output partially inhibits the ignition signal in the ignition circuit 9 by the inhibition circuit 12, and the electric heating element 3 becomes fully energized again, reaching the oil temperature control temperature. Then, the temperature control circuit 13 keeps the oil temperature constant.

Figure 2 shows a part of the specific circuit in Figure 1.
Items with the same reference numerals as in the figure indicate the same items, and
15 is a power transformer, 16 is a bridge diode, 17
, 18 and 19 are voltage comparators, and 20 is a Zener diode. .

The circuit of FIG. 2 operates as follows. The power control element 5 connected in series to the electric heating element 3 is ignited by a transistor 21 configured as an ignition circuit and energized. The heat generated by the electric heating element 3 heats the container 6, raising its temperature. When the heat-sensitive sensor 7 comes into contact with the container 6, the resistance value of the heat-sensitive sensor 7 (
Rth) changes. Resistor 2 is used for the resistance of thermal sensor 7.
5 are connected in series, and this connection point is connected to one input terminal of each voltage comparator 17, 18, and 19, respectively. The reference voltage of the voltage comparator 17 is the voltage of the thermal sensor 7.
The output of the voltage comparator 17 is set to be at a high level when the resistance value reaches a value at a first temperature slightly lower than the boiling point of water. The output of the voltage comparator 17 is connected to the pace of a transistor 22, which is connected to the transformer 15, resistors 26, 27, and a capacitor 28, so that below a first temperature, the transistor 22 is turned off and the first When the temperature is reached, the transistor 22 turns on and off in synchronization with the half-wave of the power supply.

The reference voltage of the voltage comparator 18 is set so that the output becomes a low level at a second temperature slightly higher than the boiling point of water, and this output is connected to the reference voltage of the voltage comparator 170 via a resistor 29. Therefore, when the second temperature is reached, the output of the voltage comparator 17 becomes low level again.
Transistor 22 is turned off. A reference voltage corresponding to the control temperature of the container 6 is input to the voltage comparator 19, and temperature control is performed by this voltage comparator 19.

Transistor 23, 24-diode 30, resistor 31
35 and the like is a zero-phase detection circuit of the power supply, and the transistor 23 generates an ignition pulse in synchronization with the zero-phase of the power supply, so the power control element 5 is also turned on in synchronization with the zero-phase.・It will turn off.

FIG. 3 shows the relative relationship between each set temperature.

When the power is turned on, a current as shown in A in FIG. 4 flows through the electric heating element during a period t until the first temperature T1 is reached, and a period 1 from the first temperature TI to the second temperature T2 flows through the electric heating element. ．． In this case, a part of the ignition pulse is inhibited by the on/off operation of the transistor 220, so that a current as shown in FIG. 4B flows through the electric heating element.

When the second temperature T2 is exceeded, it is again as shown in FIG. 4A! Ki 3rd
Rth in the figure indicates the state of change in resistance value of the heat-sensitive sensor (+-mister) 7.

According to the above configuration, even when the deep fryer is filled with water and is continuously energized, the power is reduced near the boiling point of the water, so the temperature rise of the main unit itself can be suppressed to a low level. In addition to being able to be formed into a smaller size, the reliability of electronic components, mechanical components, etc. can be improved. What's more, it has a short startup time, and when controlling tempura cooking, it returns to the original power, so the oil temperature returns easily.
Good cooking performance can be achieved. Furthermore, even if water is mixed in the tempura oil, it is heated slowly near the boiling point of water, so it is possible to prevent the oil from scattering, and it is possible to provide a cooking utensil with good usability.

[Brief explanation of the drawing]

FIG. 1 is an electrical configuration diagram of an embodiment of the present invention, FIG. 2 is a specific circuit diagram of FIG. 1, FIG. 3 is a diagram showing the relationship between each set temperature, and FIG. It is a energization current waveform diagram. 3... Electric heating element, 5... Power control element, 6...
Cooking container, 7... Heat sensitive sensor, 8... Power supply circuit, 9
...Ignition circuit, 10...First temperature detection circuit, 11
...Second temperature detection circuit, 12...Prohibition circuit, 13
...Temperature control circuit, 17,18.19...Voltage comparator. Figure 1 Figure 4

Claims (1)

[Claims] an electric heating element for heating a cooking vessel; a heat-sensitive sensor for detecting the temperature of the cooking vessel; and a heat-sensitive sensor associated with the heat-sensitive sensor to control the electric heating element to adjust the temperature of the cooking vessel to the boiling point of water.
A control device equipped with a control circuit that controls at a high temperature level, a circuit that detects a first temperature that is slightly lower than the boiling point of water, and a second temperature that is slightly higher than the boiling point of water and that is lower than the control temperature. , the cooking vessel is at the first temperature and the second temperature.
and a circuit for reducing the power of the electric heating element when the temperature is between .