JPH05317164A - Rice boiler - Google Patents

Abstract

PURPOSE:To achieve a very low nose with the elimination of a fan for cooling or a lower noise with a reduction in the number of revolutions of the fan for cooling concerning a cooling structure of a rice boiling apparatus utilizing induction heating. CONSTITUTION:At least one or more air ports 17 and 18 are arranged facing the upper and lower parts of the body 1 of a rice boiling apparatus while a high frequency circuit 8 is arranged between the upper air port 18 and the lower air port 17. Thus, a natural convection is induced to cool the high frequency circuit 8 efficiently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for heat generating parts of a high frequency circuit of a rice cooker using induction heating.

[0002]

2. Description of the Related Art In recent years, rice cookers utilizing induction heating have been put into practical use.

A conventional rice cooker using induction heating will be described below. FIG. 3 is a cross-sectional view of a conventional rice cooker body configuration using induction heating.

In FIG. 3, reference numeral 1 denotes a rice cooker main body, which is provided with a pan 3 for putting food to be cooked therein and an accommodating section 2 for accommodating the pan 3, and the upper part of the rice cooker main body 1 is openably and closably covered. Then, the pan 3 can be taken out by opening and closing the upper lid 9.
Numerals 4 and 5 are heating coils for inductively heating the pot 3, which are arranged at the bottom of the pot 3 and the side surface lower part. The heating coils 4 and 5 are placed on the support base 6 with a gap therebetween, and a plurality of ferrite cores 7 that absorb leakage magnetic flux are radially provided below the support base 6. Reference numeral 12 is a ring-shaped shield metal plate provided on the side body of the rice cooker body 1 facing the heating coil 5 for preventing leakage of high-frequency magnetic flux. Reference numeral 10 denotes a temperature detecting device for detecting the temperature of the pot 3, which is provided so as to contact the center of the bottom of the pot 3. The signal from the temperature detecting device 10 is input to the control circuit 19. The control circuit 19 controls the oscillating operation of the high-frequency circuit 8 provided at the bottom of the rice cooker body 1 that supplies high-frequency currents to the heating coils 4 and 5, and controls the operation display unit 11 provided at the top of the rice cooker body 1. Also do. Reference numeral 13 is a cooling fan for cooling the heat-generating components and the cooling fins to which the semiconductor switching elements of the high frequency circuit 8 are attached. Reference numeral 14 denotes an intake port for sucking the cooling air by the cooling fan 13 provided at the bottom of the rice cooker body 1, and reference numeral 15 denotes an exhaust port provided at the lower portion of the side surface body of the rice cooker body 1 opposite to the intake port 14.

Regarding the rice cooker configured as described above,
The operation will be described below. First, the pan 3 is the storage part 2.
When the rice cooking mode is selected on the operation display unit 11, the control circuit 19 operates the high frequency circuit 8 and the cooling fan 13 rotates. Cooling fan 13
Sucks the outside air from the intake port 14, flows between the bottom of the rice cooker main body 1 and the substrate of the high-frequency circuit 8, and cools the cooling fins and heat-generating components to which the semiconductor switching elements of the high-frequency circuit 8 are attached. From the exhaust port to the rice cooker body 1
It is discharged outside.

[0006]

However, in the above-mentioned conventional configuration, the cooling fan 13 rotates at 1500 to 2000 rpm to cool the cooling fins and the heat-generating components to which the semiconductor switching elements of the high frequency circuit 8 are attached. However, the noise is as high as 40 dB, which is very annoying, and the cooling air of the cooling fan 13 flows from the bottom of the rice cooker body 1 to the opposite side bottom along the bottom of the rice cooker body 1 so that the cooling efficiency is poor and therefore In addition, there is a problem that the rotation speed of the cooling fan 13 cannot be reduced.

The present invention solves the above-mentioned conventional problems. By disposing the high-frequency circuit so as to increase the cooling efficiency, the cooling fan is eliminated and the rice cooker produces almost no noise, or An object of the present invention is to provide a rice cooker capable of extremely reducing noise by reducing the fan rotation speed of a cooling fan extremely.

[0008]

To achieve this object, a rice cooker of the present invention comprises a rice cooker body, a pot for putting food in and out of the rice cooker body, and a heating coil for inductively heating the pot. A high-frequency circuit for supplying a high-frequency current to the heating coil, and a control circuit for controlling the operation of the high-frequency circuit, wherein at least one or more vent holes are provided facing the upper and lower parts of the rice cooker body, and the high-frequency circuit is provided. The circuit is arranged between the upper vent and the lower vent.

[0009]

With this structure, the air in the rice cooker heated by the cooling fins and the heat-generating components to which the semiconductor switching elements in the high frequency circuit are attached rises between the standing high frequency circuit board and the side body of the rice cooker body. Then, go out of the rice cooker body through the ventilation hole provided on the upper side of the rice cooker body. When warmed air rises along the standing high-frequency circuit board and the side body of the rice cooker body, outside air flows in from the bottom or side bottom of the rice cooker body, which can cool the heat-generating components of the high-frequency circuit. Natural convection of the air inside occurs, and it is possible to cool the heat-generating components of the high-frequency circuit without forcibly cooling it with a cooling fan, or it is possible to keep the rotation speed extremely low even if a cooling fan is used. ..

[0010]

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

In FIG. 1, reference numeral 1 denotes a rice cooker main body, which is provided with a pot 3 for putting food to be cooked therein and an accommodating portion 2 for accommodating the pan 3, and the upper part of the rice cooker main body 1 is openably and closably covered. Then, the pan 3 can be taken out by opening and closing the upper lid 9.
Numerals 4 and 5 are heating coils for inductively heating the pot 3, which are arranged at the bottom of the pot 3 and the side surface lower part. The heating coils 4 and 5 are placed on the support base 6 with a gap therebetween, and a plurality of ferrite cores 7 that absorb leakage magnetic flux are radially provided below the support base 6. Reference numeral 12 is a ring-shaped shield metal plate provided on the side body of the rice cooker body 1 facing the heating coil 5 for preventing leakage of high-frequency magnetic flux. Reference numeral 10 denotes a temperature detecting device for detecting the temperature of the pot 3, which is provided so as to contact the center of the bottom of the pot 3. The signal from the temperature detecting device 10 is input to the control circuit 19. The control circuit 19 controls the oscillating operation of the high-frequency circuit 8 provided at the bottom of the rice cooker body 1 that supplies high-frequency currents to the heating coils 4 and 5, and controls the operation display unit 11 provided at the top of the rice cooker body 1. Also do. The high frequency circuit 8 is attached to one side body of the rice cooker body 1 along the body so that the board side serves as the heating coil 5. A vent 16 is provided in the lower bottom of the rice cooker body 1 of the attached high-frequency circuit 8, a vent 17 is provided in the lower part of the side body, and a vent 18 is provided in the upper part. These vent holes 16, 17, and 18 are provided on one side body side of the rice cooker body 1.

FIG. 2 is a block diagram of an electric circuit according to an embodiment of the present invention, in which reference numeral 21 is an AC power source, to which a rectifier 22 is connected. On the output side of the rectifier 22, a resonance circuit of a smoothing capacitor 23, heating coils 4, 5 and a resonance capacitor 24,
The semiconductor switching element 26 and the diode 25 connected in anti-parallel are connected. Reference numeral 19 is a control circuit for controlling the operation of the high frequency circuit 8, which detects and controls an input current control circuit 29 for controlling the input current by the signal of the current transformer 27 for detecting the input current and a voltage across the semiconductor switching element 26. It comprises a voltage control circuit 28 and a comparison circuit 30 which compares the signal level of the input current control circuit 29 with the signal level of the voltage control circuit 28 and outputs the result to the drive circuit 20. The drive circuit 20 is a drive circuit that drives the semiconductor switching element 26.

Regarding the rice cooker configured as described above,
The operation will be described. When the pan 3 containing rice and water is inserted into the storage unit 2 and the rice cooking mode is selected on the operation display unit 11, the control circuit 19 operates the high frequency circuit 8, and the high frequency circuit 8 causes the heating coils 4 and 5 to operate. Supply high frequency current to the pan 3
Eddy current is generated at the bottom of the pot, and the pot 3 itself heats up to start cooking rice. Since the input power of the rice cooker reaches 1200 W, the semiconductor switching element 26, the diode 25, the resonance capacitor 24, the rectifier 22 and the like of the high frequency circuit 8 self-heat. The air around the high-frequency circuit 8 heated by the heat-generating components of the high-frequency circuit 8 rises between the substrate of the high-frequency circuit 8 and the side body of the rice cooker main body 1,
The rice cooker body 1 goes out of the rice cooker body 1 through a vent 18 provided on the upper side surface of the rice cooker body 1. When warmed air rises along the substrate of the high-frequency circuit 8 and the side body of the rice cooker body 1, the outside air is released from the ventilation hole 16 at the bottom of the rice cooker body 1 or the ventilation hole 17 at the lower side of the rice cooker body 1. Natural convection of air that flows into the rice cooker body 1 and flows between the substrate of the high-frequency circuit 8 and the side body of the rice cooker body 1 occurs.
This natural convection can sufficiently cool the heat-generating components such as the semiconductor switching element 26, the diode 25, the resonance capacitor 24, and the rectifier 22 without forced cooling by the cooling fan.

Although the cooling fan is omitted in the above-mentioned embodiment, although not shown in the figure, a cooling fan is provided above the vent hole 16 at the bottom of the rice cooker body 1 and the side body of the rice cooker body 1 is provided. When the cooling air is sent from the bottom to the top along the above, the number of rotations of the cooling fan can be made extremely low, and the rice cooker can obtain the cooling effect more than the above-described embodiment with low noise.

[0015]

As described above, according to the present invention, the high-frequency circuit board is vertically installed along one side body of the rice cooker body, and the vent hole and the side surface are provided on the lower bottom portion of the attached high-frequency circuit rice cooker body. By providing a ventilation hole in the lower part and a ventilation hole in the upper part, natural convection of air is induced and the cooling fan is abolished, or the rotation speed of the cooling fan can be drastically reduced to significantly reduce noise. It is possible to realize a rice cooker that uses low and excellent induction heating.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a rice cooker body configuration according to an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of a rice cooker according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional rice cooker body configuration.

[Explanation of symbols]

 1 Rice cooker body 3 Pan 4,5 Heating coil 8 High frequency circuit 16, 17, 18 Vent 19 Control circuit

Claims (1)

[Claims] 1. A rice cooker main body, a pan which can be put in and taken out of the rice cooker main body and which holds a food item, a heating coil for induction heating the pan, a high frequency circuit for supplying a high frequency current to the heating coil, and an operation of the high frequency circuit. A rice cooker comprising a control circuit for controlling, at least one or more ventilation holes are provided facing the upper and lower parts of the rice cooker body, and the high-frequency circuit is arranged between the upper and lower ventilation holes. vessel.