JP3255705B2 - rice cooker - Google Patents

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 a heat-generating component of a high frequency circuit of a rice cooker utilizing induction heating.

[0002]

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

[0003] A conventional rice cooker utilizing induction heating will be described below. FIG. 3 is a cross-sectional view of a conventional rice cooker body configuration using induction heating.

[0004] In FIG. 3, reference numeral 1 denotes a rice cooker main body, which is provided with a pot 3 for storing food therein and a storage section 2 for storing the pan 3, and an upper portion of the rice cooker main body 1 is openably and closably covered with an upper lid 9. The pan 3 can be taken out by opening and closing the top lid 9.
Reference numerals 4 and 5 denote heating coils for inductively heating the pan 3, which are arranged at the bottom of the pan 3 and at the lower side of the side. The heating coils 4 and 5 are mounted on a support base 6 with a gap therebetween, and a plurality of ferrite cores 7 that absorb leakage magnetic flux are provided radially below the support base 6. Reference numeral 12 denotes a ring-shaped shield metal plate provided on a side body of the rice cooker main 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 pan 3, which is provided so as to come into contact with the bottom center of the pan 3. The signal of 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 main body 1 for supplying high-frequency current to the heating coils 4 and 5, and controls the operation display section 11 provided at the top of the rice cooker main body 1. Also do. Reference numeral 13 denotes a cooling fan for cooling a cooling fin, a heat-generating component, and the like to which the semiconductor switching element of the high-frequency circuit 8 is attached. Reference numeral 14 denotes an air intake port provided at the bottom of the rice cooker main body 1 for sucking cooling air by a cooling fan 13, and reference numeral 15 denotes an exhaust port provided at a lower portion of the side body opposite to the air intake port 14 of the rice cooker main body 1.

[0005] Regarding the rice cooker configured as described above,
The operation will be described below. First, pan 3 is storage unit 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 outside air from the intake port 14 and flows between the bottom of the rice cooker main body 1 and the substrate of the high-frequency circuit 8 to cool the cooling fins, heat-generating components, etc., on which the semiconductor switching elements of the high-frequency circuit 8 are mounted, and to warm the cooling air. Is the rice cooker body 1 from the exhaust port
It is discharged outside.

[0006]

However, in the above-described conventional configuration, the cooling fan 13 is rotated at 1500 to 2000 rpm to cool the cooling fins and the heat-generating components on which the semiconductor switching elements of the high-frequency circuit 8 are mounted. Since the noise is high and the noise is as high as 40 dB, the cooling air of the cooling fan 13 flows along the bottom of the rice cooker main body 1 from the bottom of the rice cooker main body 1 to the opposite side bottom, so that the cooling efficiency is poor. Another problem is that the rotation speed of the cooling fan 13 cannot be reduced.

The present invention solves the above-mentioned conventional problems. A rice cooker which eliminates a cooling fan and has almost no noise by providing a high-frequency circuit with a mounting structure that enhances cooling efficiency, or It is an object of the present invention to provide a rice cooker in which the number of revolutions of a cooling fan can be extremely reduced to reduce noise.

[0008]

In order to achieve this object, a rice cooker according to the present invention comprises a rice cooker main body, a pan which can be put in and taken out of the rice cooker main body, and a heating coil for inductively heating the pan. 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 ventilation port is provided opposite to the upper and lower portions of the rice cooker main body, Circuit base
The plate is arranged upright between the upper vent and the lower vent.

[0009]

With this configuration, the air in the rice cooker warmed by the cooling fins and the heat-generating components mounted with the semiconductor switching elements in the high-frequency circuit rises between the raised high-frequency circuit board and the side body of the rice cooker body. And it goes out of a rice cooker main body from a vent provided in a rice cooker main body side upper part. When the warmed air rises along the high-frequency circuit board or the side body of the rice cooker body, outside air flows in from the bottom of the rice cooker body or the bottom of the rice cooker body, and the rice cooker can cool the heat-generating components of the high-frequency circuit. Natural convection of air in the air occurs, and the heat-generating components of the high-frequency circuit can be cooled without forced cooling with a cooling fan, or the number of revolutions can be kept extremely low even if a cooling fan is used. .

[0010]

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 storing food therein and a storage section 2 for storing the pan 3, and the upper portion of the rice cooker main body 1 is openably and closably covered by an upper lid 9. The pan 3 can be taken out by opening and closing the top lid 9.
Reference numerals 4 and 5 denote heating coils for inductively heating the pan 3, which are arranged at the bottom of the pan 3 and at the lower side of the side. The heating coils 4 and 5 are mounted on a support base 6 with a gap therebetween, and a plurality of ferrite cores 7 that absorb leakage magnetic flux are provided radially below the support base 6. Reference numeral 12 denotes a ring-shaped shield metal plate provided on a side body of the rice cooker main 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 pan 3, which is provided so as to come into contact with the bottom center of the pan 3. The signal of 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 main body 1 for supplying high-frequency current to the heating coils 4 and 5, and controls the operation display section 11 provided at the top of the rice cooker main body 1. Also do. The high-frequency circuit 8 is mounted upright on one side body of the rice cooker main body 1 so that the substrate side becomes the heating coil 5 along the body. A vent 16 is provided at a lower bottom portion of the rice cooker main body 1 of the attached high-frequency circuit 8, a vent 17 is provided at a lower portion of the side body, and a vent 18 is provided at an upper portion. These ventilation holes 16, 17, 18 are provided on one side body side of the rice cooker main body 1.

FIG. 2 is a block diagram showing an electric circuit according to an embodiment of the present invention. Reference numeral 21 denotes an AC power supply 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 denotes a control circuit for controlling the operation of the high-frequency circuit 8, which controls an input current control circuit 29 for controlling an input current based on a signal from a current transformer 27 for detecting the input current, and detects and controls 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 same to the drive circuit 20. The drive circuit 20 is a drive circuit that drives the semiconductor switching element 26.

[0013] The rice cooker constructed as described above,
The operation will be described. When the pot 3 containing rice and water is inserted into the storage section 2 and the rice cooking mode is selected on the operation display section 11, the control circuit 19 operates the high frequency circuit 8, and the high frequency circuit 8 Supply high-frequency current to pan 3
An eddy current is generated at the bottom of the pan, the pot 3 itself generates heat, and rice cooking is started. 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 generate heat by themselves. The air around the high-frequency circuit 8 warmed by the heat-generating components of the high-frequency circuit 8 rises between the board of the high-frequency circuit 8 and the side body of the rice cooker main body 1,
The rice cooker 1 goes out of the rice cooker main body 1 through an air vent 18 provided at the upper side of the rice cooker main body 1. When the warmed air rises along the substrate of the high-frequency circuit 8 and the side body of the rice cooker main body 1, the outside air flows from the vent 16 at the bottom of the rice cooker main body 1 or the vent 17 at the lower side of the rice cooker 1. Natural convection of air flowing into the rice cooker body 1 and flowing between the substrate of the high-frequency circuit 8 and the side body of the rice cooker body 1 occurs,
Even without forced cooling by the cooling fan, the heat generating components such as the semiconductor switching element 26, the diode 25, the resonance capacitor 24, and the rectifier 22 of the high frequency circuit 8 can be sufficiently cooled by the natural convection.

Although the cooling fan is abolished in the above embodiment, it is not shown in the drawing, but a cooling fan is provided above the ventilation port 16 at the bottom of the rice cooker main body 1 and is provided on the side body of the rice cooker main body 1. When the cooling air is sent from the bottom to the top, the number of rotations of the cooling fan can be made extremely low, and a rice cooker that can obtain a more effective cooling effect than the above-described embodiment having low noise can be realized.

[0015]

As described above, according to the present invention, the high-frequency circuit board is erected along the one side body of the rice cooker main body, and the vent hole and the side surface are provided at the lower bottom portion of the mounted high-frequency circuit cooker main body. By providing a vent at the lower part and a vent at the upper part, natural convection of air is induced, and the cooling fan is eliminated or the number of revolutions of the cooling fan can be extremely reduced, resulting in extremely low noise. A rice cooker using low and excellent induction heating can be realized.

[Brief description of the drawings]

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

FIG. 2 is a circuit 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 main body configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rice cooker main body 3 Pot 4,5 Heating coil 8 High frequency circuit 16,17,18 Vent 19 Control circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-134110 (JP, A) JP-A-63-49114 (JP, A) JP-A-4-58492 (JP, A) JP-A-2- 301986 (JP, A) Japanese Utility Model 3-30934 (JP, U) Japanese Utility Model 275014 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) A47J 27/00

Claims (1)

(57) [Claims] 1. A rice cooker main body, a pot which can be put in and taken out of the rice cooker main body, a heating coil for inductively 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. And a control circuit for controlling the rice cooker. At least one vent is provided facing the upper and lower portions of the rice cooker main body, and the substrate of the high-frequency circuit is set between the upper vent and the lower vent. rice cooker placed Te.