JPS6255854B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electric rice cooker.

Conventional electric rice cookers are equipped with a movable non-returnable temperature-sensitive rice cooking switch, which is made of members such as temperature-sensitive magnetic materials, magnets, and springs, and which detects the end of rice cooking, located in the lower part of the interior of the rice cooker. By operating a lever operating portion protruding from a window of the outer case, the movable non-returnable temperature-sensitive rice cooking switch was mechanically operated to start cooking rice. Therefore,
It is necessary to provide a space at the bottom of the rice cooker for arranging members such as a lever and a bearing member that transmits the force applied to the lever operation part to the mechanical part of the temperature-sensitive rice cooking switch, resulting in a bulky electric rice cooker. This had no choice but to lead to increased costs. Also,
The lever operation part had to be protruded from a window at the bottom of the outer case of the rice cooker, which caused a design problem.

In view of the above-mentioned drawbacks of conventional electric rice cookers, the present invention automatically starts cooking rice by applying current to the rice heater without using any mechanical parts such as levers, just by operating the rice cooking button. The purpose is to provide an electric rice cooker.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electric rice cooker according to the present invention (hereinafter referred to as the rice cooker of the present invention) will be explained below based on drawings showing embodiments thereof.

The electric rice cooker of the present invention is equipped with an electric circuit as shown in FIG. ing. In FIGS. 1 and 2, numeral 3 denotes an automatic reset type heat-responsive switch such as a make-type thermostat that closes when the rice is cooked, and as shown in FIG. thermally mounted and resistor R ₁ as shown in FIG.
connected in parallel to the capacitor 4 through the resistor
A charging/discharging circuit 5 is formed together with R ₁ and the capacitor 4 . The charging/discharging circuit 5 is connected between the A and B contact terminals of a normally open manually operated automatic return rice cooking switch 6 and an AC power source P via a rectifier 7. 8 is an electronic switch controlled by the voltage across the capacitor 4 of the charging/discharging circuit 5,
In the embodiment shown in FIG. 1, it consists of a transistor, and the output of the comparator 9 is input to its base. The voltage across the capacitor 4 is input to the + side input terminal of the comparator 9, and the voltage at the position W is divided by the resistors R ₂ and R ₃ to the − side input terminal of the comparator 9. However, the resistance R ₂
The voltage across both ends is input. The voltage across the resistor _R2 is set lower than the voltage across the capacitor 4 when the capacitor 4 is charged as described later. Therefore, the comparator 9 outputs a predetermined voltage to the base of the transistor to make the transistor conductive only when the capacitor 4 is charged. Of course, the electronic switch 8 may be a field transistor with a large input impedance as shown in FIG. In that case, the voltage across the capacitor 4 is directly input to the gate of the field transistor. Such an electronic toggle switch 8 is a relay coil.
It is connected between power supply P via RC and rectifier 7. A normally open contact RCa of the relay coil RC is connected to a power source P via the rice cooking heater 1. The automatic return type thermally responsive switch 3 is installed in a hole Q drilled in the center of the hot plate 2, as shown in FIG. 2, by means of a protective fixture 11 as shown in FIG. As shown in FIG. 4, the protective fitting 11
is an open top box 112 having a flange 111 at the top.
An upper closed box 113 is installed inside the upper closed box 113 in a state urged upward by a spring 114, and the lower surface of the ceiling of the upper closed box 113 has the above-mentioned A thermally responsive switch 3 is attached in contact with it. Therefore, the bottom of the inner pot 4 is in direct contact with the ceiling of the upper closed box 113, and the heat-responsive switch 3 can detect the rice temperature very well.
In the illustrated embodiment, the manually operated automatic return rice cooking switch 6 includes, in addition to the contact terminals A and B, a free terminal C, a contact connected in parallel to the capacitor 4 via a resistor R ₅ and a contact terminal A. It consists of terminal D. The above-mentioned manual operation automatic return rice cooking switch 6 is attached to the upper front surface of the rice cooker outer case 12 as shown in FIG. 2, and the button 61 is indicated by an arrow X as shown in FIG. By lowering the button 61 as shown in the arrow Y, the contact terminals A and B are connected, and by raising the button 61 as shown by the arrow Y, the contact terminals A and D are connected. When the button 61 is released, a spring (not shown) is attached. The force causes the button 61 to return to the intermediate position, and the contact terminals A and C remain connected. In the figure, 13 is a capacitor for smoothing the voltage at the portion indicated by W in FIG. 10 is a resistor and may be a Zener diode.

The rice cooker of the present invention constructed as described above operates as described below.

When the button 61 of the rice cooking switch 6 is turned on, the connection terminals A and B are connected. As a result, the capacitor 4 is charged with electric charge from the power source P through the resistor R ₄ , the rectifier 7, the resistor R ₆ , and the contact terminals B and A. The high voltage across the charged capacitor 4 is input to the + side terminal of the comparator 9. Therefore, a high level voltage is input from the comparator 9 to the electronic switch 8, and the electronic switch 8 becomes conductive. Then, current flows through the relay coil RC, so the relay contact RCa closes, and the rice cooking heater 1 starts cooking and heating the rice. In addition, since the rice temperature is low at the beginning of rice cooking, the make type automatic return type heat response switch 3 remains open. Eventually, when the rice is cooked through heating by the rice cooking heater 1, the heat-responsive switch 3 is closed. As a result, the charging/discharging circuit 5 discharges, and the voltage across the capacitor 4 rapidly decreases. Therefore, only a low level voltage is output from the comparator 9, and the electronic switch 8 becomes non-conductive.
As a result, the relay coil RC stops operating, the normally open relay contact RCa opens, and rice cooking automatically ends. Note that even if a power outage occurs during rice cooking, the charging/discharging circuit 5 will not be discharged, so when the power outage ends, rice cooking will automatically continue again, and there will be no problem. To stop rice cooking during rice cooking, the charging/discharging circuit 5 is discharged by raising the button 61 of the rice cooking switch 6 and connecting the connection terminals A and D. By doing this, it is possible to stop heating the rice.

As described above, the rice cooker of the present invention does not require a space to house mechanical parts such as levers and bearing members, so the electric rice cooker can be small in size, and a significant cost reduction can be achieved. Moreover, since mechanical members such as levers and bearing members are not used, there is also the advantage that there is no need to assemble these members without any dimensional errors. Additionally, the rice cooker's button can be attached anywhere on the outer case of the rice cooker without having to drill a window, making this electric rice cooker an excellent design.

[Brief explanation of the drawing]

The drawings are all for explaining embodiments of the rice cooker of the present invention, and FIG. 1 is a main electric circuit diagram of the rice cooker of the present invention, FIG. 2 is a longitudinal end view of the rice cooker of the present invention, and FIG. The figure is another main electrical circuit diagram of the rice cooker of the present invention, Figure 4 is a cross-sectional view of the main parts of the heat-responsive switch and its holding fixture of the rice cooker of the present invention, and Figure 5 is the button of the rice cooker switch of the rice cooker of the present invention. It is a front view. 1...Rice cooking heater, 3...Thermal response switch, 4...Capacitor, 5...Charging/discharging circuit, 6...Rice cooking switch,
7... Rectifier, 8... Electronic switch, RC... Relay coil, RCa... Relay coil contact.

Claims (1)

[Claims] 1. In an electric rice cooker that is equipped with a rice heater and automatically stops heating by the rice heater when the rice is cooked, a charging/discharging circuit in which an automatic reset type heat-responsive switch that operates when the rice is cooked is connected in parallel to a capacitor. is connected to a power source via a manually operated automatic reset type rice cooker switch and a rectifier, and an electronic switch controlled by the voltage across the capacitor of the charging/discharging circuit is connected between the power source via a relay coil, and the rice cooker is activated. An electric rice cooker characterized in that it is connected to a power source via the relay contact.