JPH07136059A - Induction heating type rice cooker - Google Patents

Abstract

PURPOSE:To obviate the necessity of using a blowing fan for cooling by improving the cooling effect of the heat sink of an inverter circuit device. CONSTITUTION:As for an induction heating type rice cooker in which rice is cooked by applying induction-heating to an inner pan accommodated in the protecting frame of a body 1 by the high frequency magnetic field generated from an induction heating coil connected with an inverter circuit device 4, a heat sink 10 is installed at the position cooled by the natural convection of the air inside the body 1 between an air intake hole 8 formed in the lower part of the body 1 and an exhaust hole 9 formed in the upper part of the body 1, and the high temperature part of the inverter circuit device 4 is installed on the heat sink 10. Further, a temperature detection element 11 is installed in a thermally joined form on the heat sink 10, and the inverter circuit device 4 performs control so that the heating is reduced or suspended by varying the output of the inductive heating, when the temperature detection element 11 reaches a previously determined temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating type rice cooker having improved safety and cooling means for high temperature parts of an inverter circuit device for generating a high frequency magnetic field in an induction heating coil.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 63-5875 and Japanese Patent Laid-Open No. 62-17985 disclose an induction heating type cooker of this type having a cooling means for a high temperature component of a conventional inverter circuit device.
Japanese Laid-Open Patent Publication No. 1-276585 is known as an example of an induction heating type rice cooker. However, these are for trying to forcibly cool the inverter circuit device with a blower fan,
It is an invention that forcibly blows air to cool.

FIG. 2 shows a configuration example of an induction heating type rice cooker having a conventional cooling means. A protective frame 2 forming an inner wall of the main body 1 is attached, and an induction heating coil 3 is attached to a bottom surface of the protective frame 2. An inverter circuit device 4 is attached to the lower inside of the main body 1, and the inverter circuit device 4 is electrically connected to the induction heating coil 3. An inner hook 5 is detachably inserted into the protective frame 2 and held therein. A temperature sensor 6 for obtaining temperature information is attached to the bottom of the protective frame 2, and abuts on the bottom of the inner pot 5 to be thermally coupled.

An intake hole 18 in which a plurality of lattice-shaped holes are combined is provided at the bottom of the main body 1 or at a lower portion of the side surface, and similarly, at a lower portion of the main body 1 or at a lower portion of the side surface, for example, the intake hole
Exhaust hole 1 in which a plurality of grid-like holes are combined diagonally
9 is provided. The inverter circuit device 4 is provided with a heat sink 10 for cooling high-temperature parts, and is arranged above the intake hole 18. Intake hole 18 and exhaust hole 1
Since 9 has almost no difference in height and natural convection does not occur,
In order to forcibly cool the heat sink 10, a blower fan 11 and an electric motor 12 are provided above the intake hole 18 of the inverter circuit device 4.

[0005]

In such a conventional configuration, a blower fan for forced cooling and an electric motor are indispensable. In particular, the former induction heating cooker, that is, the electromagnetic cooker uses an unspecified pot and the power and time used depend on the cooking menu, so even under various conditions, the inverter circuit device is cooled to prevent abnormal heating. It was necessary to leave a sufficient margin for performance, and forced cooling with a blower fan was essential. Also, in the latter induction heating type rice cooker, the electric motor 12 is required to rotate the blower fan 11, many components are required, the number of assembling steps is large, the cost is high, and the main body 1 must be large. there were. Further, in the rice cooker, it is common to use rice for a timer reservation before getting up in the early morning, and there is a problem that the wind noise caused by the blower fan 11 becomes annoying and awakens.

Further, as shown in Japanese Utility Model Laid-Open No. 3-30934, there is one in which a blower fan is not provided and a cooling means composed of a heat sink is provided in the vicinity of the power supply circuit device. It does not have passages that are cooled by natural convection and does not have positive intake and exhaust holes to enhance natural convection.Therefore, it is necessary to increase the size of the main body in order to provide a margin for temperature. It was

In the rice cooker, as the rice cooking process progresses, the electric power supplied is appropriately changed according to the rice cooking capacity at that time, and the heating control is generally performed as in "Initial choro choro medium papa ...". However, it can be controlled by the rice cooker side without changing it according to the user's intention, and in the induction heating rice cooker, the conditions such as the pan, cooking menu, power input, and time are specified within a very narrow range. Therefore, the present invention is limited to the induction heating type rice cooker, and the blowing fan and the electric motor are eliminated, and it is an object of the present invention to sufficiently cool the high temperature components of the inverter circuit device.

[0008]

The present invention has been made to solve the above-mentioned problems, and is housed in a protective frame of a main body by a high frequency magnetic field generated from an induction heating coil connected to an inverter circuit device. In an induction heating type rice cooker that induction-heats and cooks rice in an inner pot, an intake hole is provided below the main body and an exhaust hole is provided above the main body in order to positively increase the natural convection effect without enlarging the main body. The air passage for cooling by natural convection of the air inside the main body is configured between the exhaust port and the exhaust hole, and a heat sink is provided at a position where it is effectively cooled by the natural convection. It is installed.
Of course, the sizes of the main body, the air intake hole, the exhaust hole, and the heat sink are set to the optimum sizes according to the heat generation amount of the high temperature parts of the inverter circuit device due to the increase or decrease of the heat during cooking rice.

Further, the temperature detecting element is attached to the heat sink by being thermally coupled, and when the temperature detecting element reaches a predetermined temperature due to blocking of the intake hole or the exhaust hole, the inverter circuit device is induction-heated. The output was changed so as to reduce the amount or stop the induction heating.

[0010]

According to the structure of the present invention, the air heated by the induction heating coil, the inverter circuit device and the protective frame, which become high in temperature during rice cooking, rises and is discharged from the exhaust hole, and the substitute outside air is discharged from the intake hole. An effective air flow is created that is inhaled. In addition, the air around the heat sink is also heated by the heat sink and rises, and a flow of air due to natural convection occurs inside the main body from the lower side to the upper side. The heat sink arranged in the air flow path between the intake hole and the exhaust hole inside the main body is cooled by this air flow, and the high temperature components of the inverter circuit device attached to the heat sink are also effectively cooled.

Further, when the temperature of the heat sink becomes an abnormal temperature such as the flow of air in which the intake holes and the exhaust holes are blocked becomes poor, the temperature detecting element detects a predetermined temperature, and the inverter circuit device induces induction heating. The output is changed so as to reduce the amount or stop the induction heating to reduce the heat generation of the high temperature parts of the inverter circuit device and prevent the thermal destruction.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view of an induction heating type rice cooker to which an embodiment of the present invention is applied.

In FIG. 1, a main body 1 is provided with a protective frame 2 forming its inner wall, and an induction heating coil 3 is attached to the bottom surface of the protective frame 2. An inverter circuit device 4 is attached to the lower inside of the main body 1, and the inverter circuit device 4 is electrically connected to the induction heating coil 3.

An inner hook 5 is detachably inserted into the protective frame 2 and held therein. A temperature sensor 6 for obtaining temperature information is attached to the bottom of the protective frame 2, and abuts on the bottom of the inner pot 5 to be thermally coupled. A control unit 7 is provided inside the main body 1, and the inverter circuit device 4 is provided in the control unit 7.
And the temperature sensor 6 are connected.

An intake hole 8 having a plurality of lattice-shaped holes combined therein is provided at the bottom of the main body 1, and an exhaust hole 9 having a plurality of lattice-like holes similarly combined is provided above the side surface behind the main body 1. It is provided. The inverter circuit device 4 is provided with a heat sink 10 for cooling high temperature parts,
It is arranged below the exhaust hole 9.

A temperature detecting element 11 is attached to the heat sink 10 so as to be thermally coupled. The temperature detecting element 11 closes its contact at a predetermined operating temperature or higher, and when the temperature becomes lower than the operating temperature, the contact is closed again. It is an automatic reset type thermostat that opens. The inverter circuit device 4 controls so that when the temperature detecting element 11 reaches a predetermined temperature, the output is changed so as to reduce the induction heating amount or stop the induction heating.

The operation of this embodiment having the above structure will be described below.

The user puts the washed rice and an appropriate amount of water in the inner pot 5 and inserts it into the protective frame 2. Next, when a rice cooking switch (not shown) is operated, the rice cooking operation is started by the operation of the control unit 7. For cooking rice, "the beginning chopped choppa ..."
According to the legend, it is necessary to adjust the fire as it progresses. When the rice cooking is started by the operation of the user, the inverter circuit device 4 operates according to the temperature information of the temperature sensor 6 and the heating control program preset in the control unit 7, and the high frequency magnetic field generated from the induction heating coil 3 is generated. It changes and the heat generation of the inner pot 5 changes. Along with this, a part of the components of the inverter circuit device 4, for example, the switching element or the like becomes hot.

Since these components cause a failure when the temperature exceeds a certain temperature, it is necessary to keep the temperature below the certain temperature. Therefore, these components are mounted so as to be thermally coupled to the heat sink 10. Therefore, the heat of the components is transmitted to the heat sink 10, and when the ambient temperature is exceeded, the heat is radiated to the surrounding air. The heated air becomes lighter and rises, creating natural convection that draws in fresh cool air from below.

Although the air flow is small only by natural convection, the inner pot 5 becomes hot during the rice cooking operation, and the induction heating coil 3 and the protective frame 2 also receive radiant heat and become hot.
The internal air warms and rises. The rising air is the main body 1
Since it is discharged from the exhaust hole 9 provided on the upper side surface, it does not stay inside the main body 1, and instead, cold outside air is drawn into the main body 1 from the air hole 8 at the bottom of the main body 1. That is, since an air flow is generated from the lower side to the upper side, the air around the heat sink 10 arranged between the flow paths actively flows, and the heat of the heat sink 10 can be efficiently removed.

In the induction heating type rice cooker of the conventional structure, as described above, there is almost no difference in height between the intake hole and the exhaust hole, and efficient cooling cannot be achieved without forced convection cooling. According to the configuration of the present invention, as described above, the air flow is generated in the main body 1 from the lower side to the upper side, so that the cooling performance can be obtained without the blowing fan. However, the cooling performance itself is higher with the forced cooling method using a blower fan because of the amount of air flow. However, in the rice cooker, since the time and the electric power supplied are almost constant for that purpose, the heat radiation amount required by the heat sink 10 is also limited. Although the heat radiation amount is determined by the surface area of the heat sink 10, the surface area is determined so as to sufficiently secure the necessary heat radiation amount and prevent the heat sink 10 from abnormally heating (for example, 80 ° C. or higher).

When used for purposes other than rice cooking, such as boiling hot water, or when the user misuses by blocking the intake hole 8 or the exhaust hole 9, the temperature of the heat sink 10 rises and the inverter circuit The temperature of the hot parts of the device 4 also rises and there is a risk of thermal destruction. However, the temperature detecting element 11 has a predetermined constant operating temperature (for example, 90 ° C.).
Since this is a thermostat that closes the contact point, the contact point closes when the operating temperature is exceeded. The control unit 7 detects this contact operation as an electric signal, changes the output of the inverter circuit device 4, and stops the induction heating. This reduces the heat generation of high temperature parts and prevents thermal destruction. When this stopping operation is performed, the control unit 7 causes the display unit (not shown) to display an abnormality notification, interrupts the rice cooking, and notifies the user that there is a misuse. The contact of the temperature detecting element 11 is opened again when the temperature drops, and can be used normally again when the user stops misuse.

In the above embodiment, the temperature detecting element 11 is used.
Is a thermostat whose contacts close at a constant operating temperature, and the control unit 7 detects this contact operation as an electric signal, changes the output of the inverter circuit device 4, and stops the induction heating. The contact may be opened at a constant operating temperature to directly shut off the power source or the like of the inverter circuit device 4 to stop the induction heating, and an abnormal display may be provided, which has the same function and effect as the one embodiment.

Further, the temperature detecting element 11 is composed of a thermistor, a plurality of predetermined temperatures are set, and when the first temperature is reached, the heating amount is reduced to continue the rice cooking, and yet the second temperature is reached. When heating, you may stop heating and stop cooking rice. Further, the temperature detecting element 11 may be a temperature fuse that melts at a set temperature to stop heating. In this case, even if the temperature drops, the contact does not recover after melting, so failure may occur, but safety can be ensured. In comparison with a failure of a high temperature component of the inverter circuit device 4, it can be repaired at a lower cost.

[0025]

As described above, in the present invention, the intake hole is provided below the main body, the exhaust hole is provided above the main body, and the heat sink of the inverter circuit device is provided in the space between the intake hole and the exhaust hole inside the main body. A smooth natural air flow is generated from the lower part to the upper part of the main body, and efficient cooling can be achieved. As a result, the main body can be made compact without increasing its size, forced cooling by a blower fan is not required, and a blower fan and an electric motor are not required.Therefore, the number of components is reduced, the weight is reduced, and the number of assembling steps is reduced. In addition, an induction heating rice cooker can be provided at low cost. Moreover, since there is no wind noise of the blower fan, problems such as waking up with sound even if rice is cooked with a timer reservation can be solved.

Further, a temperature detecting element is attached to the heat sink by being thermally coupled, and when the temperature detecting element reaches a predetermined temperature, the inverter circuit device reduces the induction heating amount or stops the induction heating. Since the output is changed to 1), if the temperature of the heat sink is about to become abnormal, such as the intake and exhaust holes are blocked and the air flow becomes poor, the heat generation of the high temperature parts of the inverter circuit device will be reduced. It is possible to prevent thermal destruction, eliminate failure, and improve safety.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an induction heating type rice cooker according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional induction heating rice cooker.

[Explanation of symbols]

 1 Main Body 4 Inverter Circuit Device 8 Intake Hole 9 Exhaust Hole 10 Heat Sink 11 Temperature Detection Element

Claims (3)

[Claims] 1. An induction heating type rice cooker that induction-heats and cooks rice in an inner pot housed in a protective frame of a main body by a high-frequency magnetic field generated from an induction heating coil connected to an inverter circuit device, wherein the main body (1) A heat sink (10) is provided at a position where it is cooled by natural convection of air inside,
The high temperature components of the inverter circuit device (4) are attached to the heat sink (10), and the heat sink (1)
The temperature detecting element (11) is thermally coupled to and attached to (0) and the inverter circuit device (4) is connected to the temperature detecting element (1
The induction heating type rice cooker is characterized in that when the temperature of 1) reaches a predetermined temperature, the output of the induction heating is changed so as to reduce the heating amount. 2. The inverter circuit device (4) controls to change the output of the induction heating and stop the heating when the temperature detecting element (11) reaches a predetermined temperature. Induction heating rice cooker described. 3. The body (1) for the heat sink (10)
The device according to claim 1 or claim 2, which is provided at a position where it is cooled by natural convection of air inside the main body (1) between an intake hole (8) provided below and an exhaust hole (9) provided above the main body (1). Item 2. An induction heating rice cooker according to item 2.