JPH0722534B2 - rice cooker - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rice cooker using induction heating, particularly a small pot,
The present invention relates to a load detection device that detects an aluminum pot or the like and stops the operation of an inverter circuit unit.

2. Description of the Related Art In a conventional rice cooker, a load detection device is provided in the center of the bottom of a pot to mechanically detect the presence or absence of the pot.

Problems to be Solved by the Invention With such a conventional configuration, it is possible to cook rice in any kettle of any shape and material as long as it operates the load detection device. However, there is a problem that even if a user mistakenly uses the above-mentioned incorrect pot, the user can cook the rice, the rice is not delicious, and the performance is not preferable.

The present invention is to solve the above problems, by detecting the pot unsuitable for induction heating and stopping the operation of the inverter circuit unit, preventing the rice from being cooked in the pot unsuitable, delicious rice. The purpose is to prevent cooking.

Means for Solving the Problems The rice cooker of the present invention includes a pot for storing food, an accommodating portion for accommodating the pot in a suspended state, a heating coil for inductively heating the bottom of the pot, and a high-frequency current for the heating coil. And a control unit for controlling the operation of the inverter circuit unit, and a load for detecting the outer shape, material, and size of the pot to detect whether or not the pot is suitable for rice cooked by induction heating. A detection device is provided, and the control unit stops the operation of the inverter circuit unit when the load detection device detects an inappropriate hook.

Operation According to the above configuration, the load detecting device is provided, which detects the outer shape, material, and size of the pot to detect whether or not the pot is suitable for rice cooked by induction heating. When it is stored and it is detected that the pot is not suitable, the control unit stops the operation of the inverter circuit unit so that the induction heating operation of the pot is not performed. Therefore, if the user mistakenly stores an aluminum pot, a pot with a small capacity, or a pot with a dented bottom, that is, an unsuitable pot, the high-frequency magnetic field is supplied from the heating coil to these unsuitable pots. It will not be done.

Examples Hereinafter, one example of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 is a rice cooker main body using induction heating showing an embodiment of the present invention, and an accommodating portion 2 for accommodating a hanging pot 3 for storing food is provided inside the main body 1. Is configured to be openably and closably covered by the upper lid 9 so that the shuttle 3 can be taken out by opening and closing the upper lid 9. 4,5
Is a heating coil for inductively heating the kettle 3, which is placed on the support base 6, and a plurality of ferrite cores 7 for absorbing leakage magnetic flux are radially provided below the support base 6.
10 is a pan detector that moves up and down and mechanically detects the presence or absence of the kettle 3. It is provided on the bottom surface of the kettle 3, and if the kettle 3 is present,
A signal to start heating is output to the control unit 13. The control unit 13 receives the output signal of the load detection device 16 and controls the oscillation of the inverter circuit unit 8 provided at the bottom of the main body 1 which supplies the high frequency current to the heating coils 4 and 5, and at the same time It also controls the operation display unit 11 provided. Reference numeral 12 is a cooling fan for cooling the inverter circuit parts and the like, 14 and 15 are heaters for keeping the temperature of the pot 3, 14 is attached to the side surface of the housing portion 2, and 15 is attached to the upper lid 9. Cooling fan 12 and heater 14
The power supply of 15 and 15 is controlled by the control unit 13.

Next, in FIG. 2, 21 is a commercial AC power supply, 22 is a rectification circuit for rectifying the commercial AC power supply 21 into a DC power supply, and 8 is a rectification circuit.
An inverter circuit unit for converting the DC power source 22 into a high frequency power source, and a control unit 13 for controlling the operation of the inverter circuit unit 8. Reference numeral 16 is a load detection device that detects the heating state of the kettle 3 and outputs a signal to the control unit 13.

The inverter circuit unit 8 includes a capacitor 23 connected between the output terminals of the rectifier circuit 22, a series circuit of the heating coils 4 and 5 and the power switching semiconductor 26 connected between the output terminals, and the heating coils 4, 5, 4. And a resonance capacitor 24 connected in parallel to the power switching semiconductor 26 and a damper diode 25 connected in parallel to the power switching semiconductor 26 in the opposite direction.

The load detection device 16 inputs the signal of the current transformer 27 for detecting the magnitude of the input current of the inverter circuit unit 8 and outputs the output signal proportional to the input current.
And a voltage detection circuit 28 that detects the magnitude of the terminal voltage of the power switching semiconductor 26 and outputs an output signal proportional to the magnitude of this terminal voltage, and the output signals of these input detection circuits 29 and the voltage detection circuit 28. Input and compare with the output signal,
When the output signal of the input detection circuit 29 is smaller than the output signal of the voltage detection circuit 28, a small object detection circuit 30 which outputs a signal for prohibiting the supply of the base drive signal from the control unit 13 to the power switching semiconductor 26 to the control unit 13 It is composed of and.

In FIG. 3, the relationship between the input current and the terminal voltage of the power switching semiconductor 26 is shown by a normal standard pot and an aluminum pot. Here, for example, if the terminal voltage of the power switching semiconductor 26 is constant and compared, the relationship that the input current of the normal standard kettle is always larger than the input current of the aluminum kettle is established. Therefore, by comparing the terminal voltage of the power switching semiconductor 26 and the input current, it is possible to detect whether or not the cooking pot is improper, such as an aluminum pot or a small pot.

In the above configuration, when the kettle is induction-heated,
For example, the shape is such that it is made of a material such as aluminum, glass, or ceramics that is not suitable for induction heating, or that it has a large dent on the bottom or a small outer diameter. If it is improper, the load detection device 16 inputs the output signal of the input detection circuit 29 and the output signal of the voltage detection circuit 28 and compares them, and as described above with reference to FIG. Detects that the container is not suitable for cooking and outputs a heating stop signal to the control unit 13 by the small object detection circuit 30. Then, the control unit 13 controls the load detection device.
When receiving 16 output signals, the power switching semiconductor 26
Disable the base drive signal to the inverter circuit section 13
Stops the supply of high frequency current to the heating coils 4 and 5.

In the above embodiment, the load detection device compares the input current from the current transformer with the terminal voltage of the power switching semiconductor to detect whether or not it is a proper kettle, but the present invention is not limited to this. For the current detection, for example, a signal corresponding to resistance or input power may be detected, and the terminal voltage of the power switching semiconductor may achieve the effect of the present invention as the voltage of the heating coil.

In addition, in order to judge whether or not it is a proper hook according to the magnitude of the input current, by changing the comparison set value in proportion to the voltage of the power switching semiconductor, it is possible to open the hook with even higher accuracy. You can judge.

FIG. 4 is a circuit diagram showing another embodiment of the present invention, in which an input voltage detection circuit 31 in the load detection device 16 is added to detect the voltage of the AC power supply 21 to detect the input voltage detection circuit. 31
Is the voltage of the AC power supply 21 is out of the predetermined voltage range, for example,
When the voltage is out of the range of 85 to 115V, the inverter circuit unit 8 outputs a signal to the control unit 13 so as to stop outputting the base drive signal to the power switching semiconductor 26. Here, when the voltage of the input AC power supply 21 fluctuates, for example, when it becomes 100 V or more, control is performed by the voltage detection circuit 28 so as to keep the terminal voltage of the power switching semiconductor 26 constant, and the input voltage is the input voltage. Despite the increase in the voltage of the AC power supply 21 of, it is maintained at a substantially constant value,
On the other hand, when the voltage becomes 100 V or less, the input detection circuit 29 controls the input current so that the input current becomes constant, and the input current decreases linearly as the voltage of the input AC power supply 21 decreases. Therefore, it is possible to significantly suppress the fluctuation of the input power with respect to the fluctuation of the power supply voltage, as compared with the rice cooker heated by the conventional heater.

EFFECTS OF THE INVENTION As is apparent from the above description of the embodiments, the present invention has the following effects.

(1) The load detection device detects a pot of material that cannot be induction-heated, a pot that cannot sufficiently perform induction heating, such as a pot with a dented bottom or a pot of a different size, and is not suitable for the above-mentioned induction heating. When the cooker is detected, the operation of the inverter circuit section is stopped so that the rice is not cooked. Therefore, it is possible to prevent the cooked rice from being cooked with the core due to insufficient heating of the cooker. It is possible to prevent the rice that is not delicious from being cooked due to misuse by the user.

(2) When a kettle with a small capacity and a small capacity, especially a kettle with a small depth, is to be hung and stored in the storage portion, the distance from the heating coil to the bottom of the kettle becomes long. Even when the container is stored, it is possible to reliably detect the unsuitability of the hook. In particular, if the stove is hung in the stowage and stored, it is not possible to check the distance between the heating coil and the bottom of the stove, but the load detection device described above ensures reliable detection even with such a stove. Yes, you can stop the rice cooking operation.

(3) In the case of induction heating the cooker with a heating coil, if the distance between the bottom of the cooker and the heating coil becomes long, it is almost impossible to induction heat the cooker and the magnetic field generated from the heating coil leaks out of the rice cooker body. Although it becomes easier, in the above-described load detection device, the operation of the inverter circuit unit is stopped, so that the magnetic field leakage from the inverter circuit unit can be prevented and the performance of the rice cooker can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a rice cooker showing an embodiment of the present invention, FIG. 2 is a circuit diagram of the rice cooker, and FIG. 3 is a relationship between an input current of the rice cooker and a power switching semiconductor voltage. The characteristic diagram and FIG. 4 are other circuit diagrams of the rice cooker. 2 ... storage part, 3 ... pot, 4,5 ... heating coil, 8 ...
Inverter circuit, 13 ... Control, 16 ... Load detection device.

Claims (1)

[Claims] Claim: What is claimed is: 1. A kettle for holding food, an accommodating section for accommodating the kettle in a suspended state, a heating coil for inductively heating the bottom of the kettle, an inverter circuit section for supplying high-frequency current to the heating coil, and an inverter circuit. A control unit for controlling the operation of the pot and a load detection device for detecting the outer shape, material, and size of the pot to detect whether or not the pot is suitable for rice cooked by induction heating. A rice cooker that stops the operation of the inverter circuit section when a detection device detects an inappropriate pot.