JPH03261420A - Rice cooker - Google Patents

Abstract

PURPOSE:To execute the optimal setting of electric energy and a heating time in any rice cooking quantity and to always execute deliciously rice cooking by constituting the rice cooker so that a control circuit adjusts continuously the high-frequency current quantity supplied to a heating coil from an inverter circuit. CONSTITUTION:A heating coil 4 and 5 are connected in parallel to a resonance capacitor 18, constitute a resonance circuit, and a control circuit 13 controls an ON-OFF operation of a switching transistor 19. The control circuit 13 varies the conduction time of the switching transistor 19 in accordance with output signals of a weight detector 20 and a temperature detector 21, that is, the rice cooking quantity in a container 13 and its temperature, controls automatically high-frequency electric energy supplied to the heating coil 4 and 5, and sets correctly the electric energy and the heating time. That is, in accordance with the rice cooking quantity in the container 13, the control circuit 13 varies continuously an oscillation frequency of an inverter circuit 8 and adjusts automatically the input power, therefore, the rice cooking quantity even in any container 13, rice can always be cooked deliciously.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a rice cooker that uses induction heating, and in particular, a rice cooker that cooks rice by continuously varying the amount of electricity depending on the amount of rice to be cooked. It is.

Conventional technology Conventional rice cookers use a sheathed heater as a heat source, and the sheathed heater is turned off at a constant time (e.g. 16 seconds cycle) using a triac or the like depending on the amount of rice being cooked.
The amount of electricity is automatically controlled.

Problems to be Solved by the Invention With such a conventional configuration, it is only possible to automatically control the amount of electric power through ON-OFF control, and since the sheathed heater has preheating, the response is slow, making it difficult to rapidly change the temperature of the pot. Have difficulty. In addition, there is a temperature difference in the pot when the sheathed heater is turned on and off, and the temperature of the pot rises in steps, so there is a large variation in temperature detection at the timing of detecting the temperature of the pot. It was difficult to control the power, and it was not possible to always cook delicious rice.

Also, if I made a mistake in the amount of water, I could not cook delicious rice.

The present invention solves these problems, and its first purpose is to quickly set the power amount and heating time optimally for any amount of rice to be cooked, and to cook rice consistently and deliciously.

The second purpose is to quickly set the power amount and heating time optimally no matter the amount of rice and water, and to always cook delicious rice even if the amount of water is incorrect.

Means for Solving the Problems A first means for achieving the above-mentioned first object includes a heating coil for induction heating a container, an inverter circuit for supplying a high frequency current to the heating coil, and an inverter circuit that connects the heating coil to the heating coil. a control circuit that controls a high-frequency current supplied to the container, a rice cooking amount detector that detects the amount of cooked rice in the container, and a temperature sensor that detects the temperature of the container, the rice cooking amount detector and the temperature detector. The control circuit is configured to continuously adjust the amount of high-frequency current that the inverter circuit supplies to the heating coil in accordance with the output signal of the heating coil.

In addition, the second means for achieving the second objective is as follows:
Water amount detection means for detecting the amount of water in the container is provided, and the control circuit is configured to cause the inverter circuit to supply signals to the heating coil according to output signals from the water amount detection means, the rice cooking amount detector, and the temperature sensor. The amount of high-frequency current is continuously adjusted.

Operation In the rice cooker of the present invention, rice and water are placed in a container, and the inverter circuit supplies high-frequency current to the heating coil to start cooking the rice.In the pre-cooking process, the control circuit operates to ensure that the rice absorbs sufficient moisture. By varying the oscillation frequency of the inverter circuit according to the amount of rice cooked in the container and its temperature, or the amount of cooked rice, amount of water, and temperature, the optimal amount of electricity and heating time can be set to ensure that rice absorbs sufficient moisture. let Next, in the cooking process, the rice is cooked all at once at maximum power. In the steaming process, the control circuit changes the oscillation frequency of the inverter circuit according to the amount and temperature of the cooked rice in the container, or the amount of cooked rice, the amount of water, and its temperature, so as to obtain the optimum amount of electric power. Set the heating time and steam the rice.

In this way, the control circuit changes the heating time and the oscillation frequency of the inverter circuit so that the power is appropriate for each rice cooking process, depending on the amount of rice cooked and its temperature, or depending on the amount of rice cooked, the amount of water, and the temperature. This is to adjust the amount of electricity.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is an electrical circuit diagram of a jar rice cooker using induction heating showing a first embodiment of the present invention that achieves the first object.
12 is a commercial power source, to which the inverter circuit 8 is connected. The inverter circuit 8 includes a rectifier 14 connected to a commercial power supply 12, a check coil 16 connected in series with a capacitor 16 connected to the output terminal of the rectifier 14, a smoothing capacitor 17, and a resonant capacitor 18 connected to the smoothing capacitor 17. and a switching transistor 19 having built-in diodes connected in antiparallel.

Capacitor 16 and choke coil 16! : constitutes a filter circuit.

The heating coils 4 and 6 are connected in parallel with a resonant capacitor 18 to form a resonant circuit.

The control circuit 13 turns on the switching transistor 19.
-,0FFJ production is controlled. 2o is a weight detector which is a kind of rice cooking amount detector in the container 3 provided at the bottom of the container 3; this is, for example, a weight sensor;
The amount of cooked rice is outputted to the control circuit 13 according to the amount of cooked rice.

Reference numeral 21 denotes a temperature sensor provided at the bottom of the container 3, which may be, for example, a thermistor, and the temperature sensor 21 is sent to the control circuit 13.

In Fig. 2, 1 is a jar rice cooker main body, inside which is provided a storage part 2 for storing a pot 3, which is a container for holding rice and water.
The upper part of the main body 1 is covered with an upper lid 9 so as to be openable and closable, and the pot 3 can be taken out by opening and closing the upper lid 9. 4 and 5 are heating coils for inductively heating the pot 3, which are placed on a support base e, and a plurality of ferrite cores 7 are provided radially below the support base 6 to absorb leakage magnetic flux. . 10 moves up and down, mechanically pot 3
This is a load detection device that detects whether or not the container is suitable for cooking rice. Outputs a signal indicating that it is a pot. The control section 13 controls the oscillation of an inverter circuit section 8 provided at the bottom of the main body 1 that supplies high-frequency current to the heating coils 4 and 6, and also controls the operation display section 11 provided at the top of the main body 1.

In the above configuration, the control circuit 13 responds to the output signals of the weight sensor 20 and the temperature sensor 21.

That is, depending on the amount of cooked rice in the container 13 and its temperature.

The conduction time of the switching transistor 19 is varied, the amount of high-frequency power supplied to the heating coils 4 and 6 is automatically controlled, and the amount of power and heating time are appropriately set.

In other words, since the control circuit 13 continuously changes the oscillation frequency of the inverter circuit 8 and automatically adjusts the input power according to the amount of rice cooked in the container 13, the rice always tastes delicious regardless of the amount of rice cooked in the container 13. It can be cooked.

In addition, when adjusting the amount of electricity, the input power is automatically adjusted by continuously changing the oscillation frequency of the inverter circuit, so the voltage drops by several volts at heating 01 as in conventional 0N-OFF control. , it is possible to eliminate defects such as beats caused by fluctuations in input power and fluctuations in the rotational speed of the fan motor due to voltage fluctuations at the time of 0N-077.

Next, FIG. 3 shows a second embodiment that achieves the second objective. In the figure, a water amount detection means 32 for detecting the amount of water in the container 3 is provided at the bottom of the container 3. Output to the control circuit 13.

In the above configuration, the control circuit 13 adjusts the heating time and the temperature according to the output signals of the weight detector 2o, the temperature sensor 21, and the water amount detection means 32, that is, according to the amount of rice and water in the container 13 and the temperature thereof. , the conduction time of the switching transistor 19 is varied, and the amount of high-frequency power supplied to the heating coils 4 and 6 is automatically controlled to appropriately set the amount of power.

Depending on the amount of rice and water in the pickle container 13 and its temperature, the control circuit 13 may, for example, lengthen the heating time or increase the input power if the amount of water is larger than the amount of rice. Since the input power is automatically adjusted by continuously changing the heating time and the oscillation frequency of the inverter circuit 8, the rice will always be delicious even if the amount of rice and water in the container 13 is incorrect. You can cook it.

Although the weight detector 20, the temperature detector 21, and the water amount detection means 32 are respectively provided at the bottom of the container 3, the present invention is not limited to this, and they may be provided at any position where the respective functions can be achieved. It's okay.

In addition, although a weight detector was used as a means for detecting the amount of cooked rice, the method is not limited to this, and the amount of cooked rice may also be determined based on the rate of temperature rise of the cooked rice.In short, the amount of cooked rice is detected. It's fine as long as it's possible.

Effects of the Invention As is clear from the description of the embodiments above, the present invention provides the following effects.

(1) Since the amount of electricity is continuously set optimally according to the amount of rice to be cooked, the temperature rise curve of the pot is smooth, and the detection accuracy of the temperature detector that detects the temperature of the pot can be greatly improved.

(2) Since the amount of rice cooked and its temperature are detected and the heating time and power amount are optimally set according to the amount and temperature of rice cooked, delicate control of heating time and amount of power is possible, and the rice is always delicious no matter the amount of rice cooked. I can cook rice.

(3) Since the amount of electricity is continuously varied, there is no variation in the amount of electricity due to a drop in the input voltage during heating.

Wind noise caused by fluctuations in fan motor rotation speed can be prevented.

(4) The amount of rice and water and its temperature are detected individually, and the heating time and power amount are optimally set according to the amount of rice and water and their temperature, so delicate heating time and power amount control is possible. This allows you to always cook delicious rice with any amount of rice and water.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram of a jar rice cooker showing a first embodiment of the present invention, Fig. 2 is a sectional view of the main body, and Fig. 3 is a diagram of a jar rice cooker showing a second embodiment of the invention. It is an electrical circuit diagram. 3... Container, 4,6... Heating coil,
8... Inverter circuit, 13... Control circuit, 20... Weight detector, 21...
Temperature detector, 32...Water amount detection means.

Claims (2)

[Claims] (1) A heating coil that inductively heats the container, an inverter circuit that supplies high-frequency current to the heating coil, a control circuit that controls the high-frequency current that the inverter circuit supplies to the heating coil, and detects the amount of cooked rice in the container. and a temperature detector that detects the temperature of the container, and according to output signals of the rice cooking amount detector and the temperature sensor,
In the rice cooker, the control circuit continuously adjusts the amount of high-frequency current that the inverter circuit supplies to the heating coil. (2) A water amount detection means for detecting the amount of water in the container is provided, and the control circuit controls the high frequency signal that the inverter circuit supplies to the heating coil according to the output signals of the water amount detection means, the rice cooking amount detector, and the temperature sensor. The rice cooker according to claim 1, wherein the amount of current is adjusted continuously.