JPH06217873A - Electromagnetic induction heating rice cooker - Google Patents

Abstract

(57) [Abstract] [Purpose] An electromagnetic induction heating rice cooker that prevents noise from being detected in the pot temperature detection unit due to the influence of the high frequency magnetic field from the heating coil and prevents false detection of the pot temperature. provide. [Structure] The pot temperature detecting unit 30 includes a temperature sensor unit 32 for detecting the temperature of the pot 16, a coil spring 33 for bringing the temperature sensor unit 32 into contact with the pot 16, and a temperature sensor unit 3
2 and a coil portion 34 for accommodating the coil spring 33,
The cylindrical portion 34 is provided with a magnetic shield 35 that blocks a high frequency magnetic field. The high-frequency magnetic field from the heating coil 18 is blocked from reaching the temperature sensor section 32 in the tubular section 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic induction heating rice cooker that cooks rice by induction heating a pot.

[0002]

2. Description of the Related Art The structure of a conventional electromagnetic induction heating rice cooker is shown in FIG.
Will be described. In the figure, reference numeral 1 is a rice cooker body, and a pot storage portion 3 for housing a pot 2 is provided in the rice cooker body 1.
A heating coil 5 is arranged on the outer bottom portion 4 of the pan storage portion 3 to induction-heat the pan 2. The pan 2 has a two-layer structure in which the outer side is a stainless steel layer and the inner side is an aluminum layer, so that induction heating is optimized. A lid 7 that is openable and closable around a shaft 6 is provided on the upper portion of the pan 2, and a hook 8 is engaged with a claw portion 9 provided on an upper side portion of the rice cooker body 1 to close the lid 7. I am trying. An inverter circuit board 10 for supplying a high-frequency current to the heating coil 5 is arranged in the lower part of the rice cooker body 1. A switching element, which is a heat-generating electronic component, is mounted on the inverter circuit board 10, and it is necessary to cool the heat-generating component and further the heating coil 5. Therefore, the cooling fan 11 is provided in the rice cooker body 1, and the outside air is taken in from the air supply port 12 provided on the bottom surface of the rice cooker body 1 to cool each component in the rice cooker body 1. The cooled gas is exhausted from the exhaust port 13 provided on the lower side surface of the rice cooker body 1. Reference numeral 14 is a temperature detection unit that abuts the outer bottom of the pot 2 and detects the temperature of the pot 4, and controls the heating output of the inverter circuit based on the temperature detected by the temperature detection unit 14.

[0003]

SUMMARY OF THE INVENTION In the above conventional configuration,
Since the temperature detector 14 is located near the heating coil 5,
The temperature detection unit 14 is affected by the high-frequency magnetic field from the heating coil 5, and noise is added to the detected temperature signal, and the heating output is controlled by the detected temperature including this noise. Although it was not at the temperature, the temperature was mistakenly detected as reaching the end-of-cooking temperature, and there was a problem that heating was stopped before the rice was cooked.

In view of the above problems, it is an object of the present invention to prevent the temperature from being erroneously detected by the high frequency magnetic field from the heating coil and to improve the cooked state of rice.

[0005]

In order to achieve the above object, the present invention provides a heating coil for inductively heating a pan, a pan temperature detector for detecting the temperature of the pan, and a high-frequency current supplied to the heating coil. And an inverter circuit for controlling the drive of the inverter circuit based on the temperature detected by the pan temperature detection unit to control the heating output, the temperature detection unit, a temperature sensor unit abutting the pan The temperature sensor unit is composed of a spring that abuts against the pan, and a tubular unit that houses the temperature sensor unit and the spring. At least the tubular unit below the spring is provided with a magnetic shielding material.

[0006]

According to the present invention, since the temperature sensor portion for detecting the temperature of the pot is housed in the tubular portion and the tubular portion is provided with the magnetic shield material, the high frequency magnetic field from the heating coil is applied to the temperature sensor portion. The temperature signal from the temperature sensor is prevented from being noisy due to the high frequency magnetic field.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, the overall construction of the electromagnetic induction heating rice cooker of this embodiment will be described with reference to FIG. In the figure, reference numeral 15 denotes a rice cooker main body, and an upper and lower part of which is provided with a lid 21 which can be opened and closed centering on a hinge portion 20, and a handle 22 provided on an upper surface of the lid 21 opens and closes the lid 21. Also, the rice cooker body 15
A pot storage portion 17 for storing the pot 16 is formed inside the container. Heating coils 18 and 19 are arranged on the outer bottom of the pan storage portion 17, and the heating coil is divided into two, an inner heating coil 18 and an outer heating coil 19. A rod-shaped ferrite core 23 is radially arranged below the heating coils 18 and 19 to prevent the high-frequency magnetic field generated from the heating coils 18 and 19 from leaking downward. Inside the rice cooker main body 15 below the ferrite core 23, a cooling fan 24, an inverter circuit board 25 provided with an inverter circuit for supplying high-frequency current to the heating coils 18, 19 and a switching element of the inverter circuit are turned on and off. Control and
Control circuit board 2 including control circuit for controlling heating output
6 are arranged, and the above-mentioned circuit boards 25,
26 and the heating coils 18 and 19 are cooled. As the cooling path, the outside air is introduced from the air supply port 27 provided at the bottom of the rice cooker main body 15, and each circuit board 25, 26 is introduced.
And after cooling the heating coils 18 and 19, the exhaust port 28
It is configured to be discharged from. Air supply port 27, exhaust port 2
The filter 8 is covered with a filter 29 to prevent harmful insects such as cockroaches from entering the rice cooker body 15.

Further, a pot temperature detecting section 30 for detecting the temperature of the pot is provided on the outer bottom of the pot 16. The temperature detected by the pan temperature detector 30 is sent to the control circuit board 26, and the control circuit board controls the switching element of the inverter circuit board 25 based on the detected temperature to control the heating output.
As shown in FIG. 1, the pot temperature detecting unit 30 has a temperature sensor unit 32 through a hole 31 provided at the bottom of the pot housing unit 17.
Directly contacts the outer bottom of the pan 16. Temperature sensor unit 32
Is composed of a thermistor 32a and an aluminum plate 32b which covers the thermistor 32a and contacts the outer bottom surface of the pot 16. The temperature sensor unit 30 is biased toward the pan 16 by the coil spring 33, and the temperature sensor unit 30 and the coil spring 33 are housed in the tubular unit 34. A cylindrical magnetic shield 35, for example, an aluminum plate is provided on the inner peripheral surface of the lower portion of the cylindrical portion 34. The magnetic shield may not be an aluminum plate but may be formed by applying a magnetic shield to the inner peripheral surface or the outer peripheral surface of the tubular portion 34, and the tubular portion 34 itself may be formed of the magnetic protective material. . Further, if the coil spring 33 is made of a magnetic shield material, the coil spring 33 performs a magnetic shield function, so that the magnetic shield material 35 is provided only on the tubular portion 34 below the coil spring 33.

Next, the operation of this embodiment will be described. When the inverter circuit board 25 is operated, the heating coils 18, 19
A high frequency current is supplied to the heating coils 18 and 19 to generate a high frequency magnetic field. The high-frequency magnetic field causes induction heating of the two-layer pan 16 made of stainless steel and aluminum. The high frequency magnetic field generated from the heating coils 18 and 19 is
Since it extends below 19 as well, the ferrite core 23 arranged below the heating coils 18 and 19 prevents the magnetic field from leaking downward, but it cannot completely block the high-frequency magnetic field. The pot temperature detecting unit 30 located near 19 is affected by the high frequency magnetic field. Especially, 20
In the case where an inverter circuit corresponding to 0 volt is used to obtain a high output, the high frequency magnetic field is naturally strong, and the influence exerted on the pan temperature detecting unit 30 is large. Therefore, the temperature detection unit 30, especially the temperature sensor unit 3 that directly detects the temperature.
2 and the lead wire (not shown) for transmitting the detection signal to the control circuit board 26 must be shielded from the high frequency magnetic field so that the detection signal does not carry noise due to the high frequency magnetic field. Therefore, the cylindrical portion 34 that houses the temperature sensor portion 32
A magnetic shielding material 35 is provided on the temperature sensor unit 32 so that a high frequency magnetic field is generated.
To prevent noise from being added to the detection signal. In particular, when induction heating is performed using an inverter circuit corresponding to 200 volts, the tubular portion 34 is extended to the lower side as much as possible because it is strongly influenced by the high frequency magnetic field to the lower side of the temperature detecting section 30. A magnetic shield is also provided on the part.

[0011]

According to the present invention, since the temperature sensor portion for detecting the temperature of the pot is housed in the tubular portion and the tubular portion is provided with the magnetic shielding material, the high frequency magnetic field from the heating coil is applied to the temperature sensor. It is possible to prevent the noise from reaching the temperature sensor and to prevent noise due to the high frequency magnetic field from being added to the temperature signal from the temperature sensor. Therefore, the rice can be cooked well without erroneously detecting the pot temperature.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an electromagnetic induction heating rice cooker according to an embodiment of the present invention.

FIG. 2 is a partially cutaway side view of the electromagnetic induction heating rice cooker.

FIG. 3 is a sectional view of a conventional electromagnetic induction heating rice cooker.

[Explanation of symbols]

 16 Pan 18 Heating Coil 25 Inverter Circuit Board 26 Control Circuit Board 30 Pan Temperature Detection Section 32 Temperature Sensor Section 33 Coil Spring (Spring) 34 Cylindrical Section 35 Magnetic Shielding Material

Claims (1)

[Claims] 1. A heating coil for inductively heating a pan, a pan temperature detection unit for detecting the temperature of the pan, an inverter circuit for supplying a high-frequency current to the heating coil, and a temperature detected by the pan temperature detection unit. And a control circuit for controlling the drive of the inverter circuit to control the heating output, the pot temperature detection unit, a temperature sensor unit that abuts the pot, and a spring that makes the temperature sensor unit abut the pot, An electromagnetic induction heating rice cooker comprising the temperature sensor section and a tubular section accommodating a spring, wherein at least the tubular section below the spring is provided with a magnetic shielding material.