JPH04313623A - Heating and cooking device - Google Patents

Abstract

PURPOSE:To enable a safety device for a cooking device to be constructed of components having small rated current values without increasing the number of the components in an inexpensive manner. CONSTITUTION:A commercial power supply is short circuited with a monitor switch 13 when a door is opened in the case that a contact point of a door switch 12 cooperated with opening or closing of a door at a heating chamber and for turning off an electrical energization for a heating source under an opened state of the door is melted and adhered and a melted part 14 formed by an electrical conductive foil on a printed circuit board is melted and cut, thereby an electrical supplying to a control power supply circuit 15 for supplying a control power to an electronic control means 11 is cut off and then an electrical energization for a heating source 2 is turned off. In addition, when an abnormal increasing in temperature in the heating chamber occurs, a fuse 22 within the control power supply circuit 15 is melted and cut with a current flowing in a thermistor 21 for sensing a temperature in the heating chamber and a supplying of a control power supply for the electronic control means 11 is shut off.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for stopping the operation of a cooking appliance having electronic control means when an abnormal condition occurs in the cooking appliance.

0002

2. Description of the Related Art When a door is opened, the power supply to a high frequency oscillation circuit is stopped by turning off a door switch that is linked to the opening and closing of the door, thereby preventing leakage of radio waves. and,
If the contact of the door switch is welded and does not turn off when the door is opened, the monitor switch that is linked to the opening and closing of the door is turned on to form a short circuit for the power supply and melt the fuse in the power supply path to the load. In this way, the power supply to the high frequency oscillation circuit is directly cut off. Although momentary, a short circuit current of several hundred amperes flows through this short circuit, which adversely affects indoor wiring, safety devices such as breakers, and monitor switch contacts. In order to reduce the negative effects of this short circuit current, a resistor is interposed in the short circuit to limit the short circuit current to the extent that it can melt the fuse in the power supply path to the load.
This is disclosed in FIG. 4 of Japanese Patent No. 4686. However, in order to directly cut off the power supply to the load, components with a large rated current capacity must be used, resulting in a large number of components and high costs.

Furthermore, the device for preventing overheating of a cooking device disclosed in Japanese Utility Model Publication No. 53-35794 directly cuts off the power supply to the load, so components with a large rated current capacity must be used. It was expensive.

0004

Problem to be Solved by the Invention: To provide a safety device for a cooker having an electronic control means without increasing the number of parts.
To be constructed at low cost using parts with small rated current capacity.

[0005]

[Means for Solving the Problems] The present invention provides a heating source, a switch means for controlling power supply from a power source to the heating source, and an electronic control means for driving and controlling the switch means.
A control power supply circuit that supplies control power to the electronic control means; and a fusing section that turns off the power supply to the control power circuit when there is an abnormality in the power supply path to the heating source, and the fusing section is connected to the control power supply. It consists of conductive circuit patterns that connect the power supply and control power supply circuits on the printed circuit board that forms the circuit. Furthermore, a plurality of the fusing parts are formed to enable reconfiguration.

[0006] Furthermore, a heating source for cooking the food in the heating chamber, a switch means for controlling power supply to the heating source, and an electronic control means for driving and controlling the switch means;
A control power supply circuit that supplies control power to this electronic control means, a negative temperature resistance change element that is connected to this control power supply circuit and detects an abnormal temperature rise in the heating chamber, and a negative temperature resistance change element that detects an abnormal temperature rise in the heating chamber. A fuse is provided that blows when it detects this, cutting off the supply of control power to the electronic control means.

[0007]

[Operation] When an abnormal state occurs in a cooking appliance that has electronic control means, the fusing part of the control power supply circuit that supplies control power to the electronic control means is fused and the power supply to the load is cut off, reducing the fusing current. It can be formed integrally on a printed circuit board.

[0008]

[Embodiment] Figures 1 and 2 show an embodiment of the cooking device of the present invention, in which 1 is a commercial power supply, 2 is a magnetron 3 for cooking food in a heating chamber (not shown), a high voltage transformer 4, etc. 5 is a magnetron thermometer that detects an abnormal temperature rise in the magnetron 3 and stops energizing the heating source, 6 is an overcurrent protection fuse, 7 is a magnetron cooling fan 8, and a heating chamber interior light. An electromagnetic relay contact 9 controls the operation, and 10 a heating output control electromagnetic relay contact that controls the supply of commercial power to the heating source 2. The relay contacts 7 and 10 are controlled to open and close by electronic control means 11.

Reference numeral 12 denotes a door switch that is turned on and off in conjunction with the opening and closing of the door (not shown) of the heating chamber, which turns on electricity to the heating source when the door is closed, and turns on electricity to the heating source when the door is opened. Turn off. 13 is a monitor switch that operates in conjunction with opening and closing of the door and is turned on when the door is opened. When the contact of the door switch 12 is welded, this monitor switch 13 short-circuits the commercial power supply 1 to melt the fusing part 14 and performs electronic control. The power supply to the control power supply circuit 15 that supplies the control power to the means 11 is stopped, and as a result, the power supply to the heating source 2 is turned off.

The fusing portion 14 is connected to a conductor foil 18 connected to a commercial power supply on a printed circuit board 17 of a primary winding circuit of a control transformer 16 forming a part of a control power supply circuit 15, and to a control transformer. The conductive foil 19 is formed by forming the conductive foil that connects the conductive foil 19 to be thinner than other parts. By forming a plurality of these fusing parts 14 in a connected manner on a printed circuit board, the conductive foil 19 and the fusing parts 14, 1
By sequentially connecting 4 with conductive wires, it is possible to easily regenerate the fused printed circuit board 17.

20 is a constant voltage circuit provided on the secondary side of the control transformer 16, and 21 is a heating chamber abnormal temperature rise detection thermistor (negative characteristic temperature This thermistor 21 is molded with epoxy resin to prevent insulation deterioration due to moisture and corrosive gas, and is attached near the exhaust port (not shown) in the heating chamber. Reference numeral 22 denotes a fuse that is blown by the current flowing through the thermistor 21 when the heating chamber temperature rises abnormally, cutting off the supply of control power to the electronic control means 11. This fuse 22 is connected to the control power supply circuit 15.
It may also be composed of a conductor pattern on a printed circuit board that forms a conductor pattern.

[0012] In this way, when an abnormal condition occurs such as welding of the door switch contact or abnormal temperature rise in the heating chamber, the fusing current that cuts off the power supply to the load can be reduced.

[0013]

[Effects of the Invention] Since the fusing part that protects the cooker from abnormal conditions is provided in the control power circuit that supplies control power to the electronic control means, and the control power circuit is turned off, the fusing current can be reduced. It is possible to prevent harmful effects on indoor wiring due to fusing current. Furthermore, since the fusing part is constructed from a conductive pattern on the printed circuit board, there is no need to increase the number of parts.
It can be constructed at low cost using parts with small rated current capacity.

[Brief explanation of drawings]

FIG. 1 is an electrical circuit diagram of a cooking device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a fusing portion of a printed circuit board according to an embodiment of the present invention.

[Explanation of symbols]

2 Heating source 10 Switch means 11 Electronic control means 15 Control power supply circuit 14, Fusing part 17 Printed circuit board 21 Negative temperature resistance change element 22 Fuse

Claims (3)

[Claims] 1. A heating source, a switch means for controlling power supply from a power source to the heating source, an electronic control means for driving and controlling the switch means, and a control power supply circuit for supplying control power to the electronic control means. and a fusing part that turns off the power supply to the control power circuit when there is an abnormality in the power supply path to the heating source, and the fusing part is connected to the power supply and control power supply on the printed circuit board forming the control power circuit. A heating cooker made up of conductive circuit patterns that connect circuits. 2. The cooking device according to claim 1, wherein a plurality of the fusing portions are formed of the conductive circuit pattern. 3. A heating source for cooking the food in the heating chamber, a switch means for controlling power supply to the heating source, an electronic control means for driving and controlling the switch means, and a control power source for the electronic control means. a control power supply circuit that supplies
A negative temperature resistance change element is connected to this control power circuit and detects an abnormal temperature rise in the heating chamber, and this negative temperature resistance change element is blown out when an abnormal temperature is detected, and the control power to the electronic control means is supplied. A heating cooker consisting of a fuse that cuts off the supply.