JPS5845126B2 - netsuoudoukaiheiki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermally responsive switch, and more particularly to a thermally responsive switch that opens and closes at the operating temperature only after passing through a predetermined temperature higher than the operating temperature at which the contacts are to be opened and closed. .

Generally, electric rice cookers are required to have a rice cooking/warming curve as shown in FIG.

After starting instant cooking, the temperature rises linearly and starts boiling at 100℃ and maintains 100℃ for a predetermined time. When the water completely evaporates, the temperature rises again and stops heating at about 140℃. decrease.

When the heat retention temperature is reached, the temperatures T2 (=70℃) and T3
(=65°C) and can be controlled on and off to maintain heat.

The electrical circuit for obtaining the above cooking rice heat retention curve is explained with reference to Fig. 2. 1 is a heater, 2 is a manually set temperature-responsive switch, and 3 is a temperature-responsive switch after opening the temperature-responsive switch 2. It is a thermally responsive switch that maintains
It is connected in parallel to the temperature responsive switch 2 and in series to the heater 1.

Therefore, the thermally responsive switch 2 used in this type of circuit has the condition that it is open at room temperature and closed only between the insulating temperature T2 and T3, and thus has a complicated structure such as combining two sets of bimetals. It became.

Therefore, the thermally responsive switch according to the present invention uses a combination of bimetallic plates and magnetic materials to open and close at the operating temperature only after passing through a predetermined temperature higher than the operating temperature at which the contacts should open and close. To provide a heat-responsive switch for heat retention that operates, has a simple structure, and is suitable for an electric rice cooker.

Hereinafter, a thermally responsive switch according to the present invention will be explained with reference to FIG.

4 is a fixed plate having a fixed contact 5; 6 is a movable plate made of a magnetic material and has a movable contact 7 which faces the fixed contact 5 and is usually separated; and 8 is a bimetal having a magnet 9 at its tip. It is a board.

Figure A shows a state in which the contacts 5 and 7 are open at room temperature, but when the bimetal plate 8 is heated and the temperature approaches T1, the bimetal plate 8 bends toward the movable plate 6 and the magnet body 9
approaches and attracts the movable plate 6, which is a magnetic material.

(See figure opening) For example, when the heater 1 stops generating heat due to the opening of the temperature responsive switch 2 shown in FIG. 2, the bimetal plate 8 bends away from the movable plate 6.
holds the movable plate 6 in a suction state, so the movable plate 6
approaches the fixed plate 4 and brings both contacts 5 and 7 into contact at the temperature T3.

(See Figure C) Then, the heater 1 generates heat via the thermally responsive switch 3 and opens the contact 5.7 at the temperature T2.

(See FIG. 2) In this way, the thermally responsive switch 3 closes or opens the contacts 5 and 7 between FIG. 2 and maintains the insulating temperature.

When the power is turned off, the temperature of the bimetal plate 8 also drops, and a force acts in the direction away from the movable plate 6, and the movable plate 6 moves away from the fixed plate 4.
As a result, the bending is prevented, and the force of attraction between the magnet body 9 and the movable plate 6 becomes greater than that of the movable plate 6, and the state shown in FIG.

As described above, the thermally responsive switch according to the present invention has a simple structure and can provide a thermally responsive switch suitable for heat retaining circuits such as electric rice cookers.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the operation of the heat-responsive switch of the present invention, FIG. 2 is a circuit diagram of an electric rice cooker, and FIG. 3 is a rice cooking/warming curve diagram of the electric rice cooker. 4...Fixed plate, 5...Fixed contact, 6.
...Movable plate, 7...Movable contact, 8...
... Bimetal plate, 9... Magnet body.

Claims (1)

[Claims] 1. A fixed plate having a fixed contact, a movable plate having a movable contact that faces the fixed contact and is normally spaced apart, and is provided with a magnetic material on at least a part, and a movable plate that faces the magnetic material When the bimetal is heated, it bends toward the movable plate, and when it reaches a predetermined first temperature, the magnet and the magnetic body are attracted to each other, and then the temperature of the bimetal is lowered. A thermally responsive switch in which the movable plate is brought close to the fixed plate at a predetermined second temperature to bring both of the contacts into contact with each other.