JPH09238827A - Rice boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a heat loss of a switching element and adopt a structure without a fan. SOLUTION: A temperature detecting means 10 is disposed near a switching element 7. The detected temperature Tx of the temperature detecting means 10 is input to a control means 12 to be compared with a preset temperature Th. If the detected temperature Tx exceeds the preset temperature Th, receipt of an input signal from a rice boiling switch 13 is rejected. If receiving was rejected, the control means 12 forces a display means 14 to perform an error indication.

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, and more particularly to a rice cooker excellent in heat loss prevention of its switching element.

[0002]

2. Description of the Related Art Generally, in an induction heating type rice cooker, a switching element (IGBT) oscillates an inverter to generate a high frequency current in a heating coil to induction heat an inner pot. When the inner pot is heated and the ambient temperature rises, for example, when the next rice is cooked continuously, the temperature of the switching element rises beyond the allowable value and may be damaged.

Conventionally, in order to prevent such damage of the switching element, a fan is provided for forced cooling, or a temperature detecting element is provided in the heat sink, and the energization of the heating coil is controlled based on the detected temperature. I was going to do it.

[0004]

However, when the fan is provided, not only the wind noise is generated due to its rotation, but also extra power is required for that purpose. Moreover,
The internal structure of the rice cooker becomes complicated due to the attachment of the fan, or the rice cooker itself becomes large in size, resulting in an increase in cost.

On the other hand, when the temperature detecting element is provided, the fan is not required, and although the above problem is solved, the energization to the heating coil is stopped (or suppressed) each time the temperature rises above the allowable value. There is a new problem that the flavor of cooked rice is impaired.

[0006] Therefore, an object of the present invention is to provide a rice cooker capable of preventing a heat loss of a switching element and adopting a fanless structure.

[0007]

In order to achieve the above object, the present invention provides a heating coil for induction heating an inner pot, an inverter for supplying a high frequency current to the heating coil, and a switching element for oscillating the inverter. And a rice cooker including a rice cooker switch for starting the induction heating, wherein temperature detecting means arranged in the vicinity of the switching element and temperature detected by the temperature detecting means exceeds a set temperature. , Control means for rejecting acceptance of an input signal from the rice cooking switch.

According to the above construction, when the temperature of the switching element is not sufficiently lowered due to continuous rice cooking or the like, acceptance of the input signal from the rice cooking switch is rejected. This allows
There is no heat loss due to the fact that the rice cooking is started and the temperature of the switching element rises. After that, if the temperature of the switching element is lowered to the set temperature by natural cooling, it is possible to prevent the temperature of the switching element from rising to heat loss even if rice cooking is started.

When the temperature detected by the temperature detecting means exceeds the set temperature, the control means is caused to display an error on the display means, or the detected temperature of the temperature detecting means exceeds the set temperature. In this case, the energization of the heating coil should be stopped until the temperature falls below the set temperature, or the time required until the temperature falls below the set temperature is estimated from the degree of decrease in the temperature detected by the temperature detection means, and the rice is displayed on the display means. More preferably, the time until the start is displayed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic view of a rice cooker according to the present invention. In this rice cooker, a lid body 2 is provided on a rice cooker body 1 so as to be openable and closable. An inner pot accommodating portion 3 is formed inside the rice cooker body 1. The inner pot accommodating portion 3 has a body portion 4 and a bottom portion 5.
The bottom portion of the bottom portion 5 has heating coils 6a and 6b spirally arranged on the inner diameter side and the outer diameter side, respectively.
A high frequency current is supplied from the inverter circuit 8 to the heating coils 6a and 6b by the switching element 7. A heat sink 9 is provided below the switching element 7 so as to be in contact therewith. A temperature sensor 10, which is a temperature detecting means, is attached near the switching element 7 of the inverter circuit 8. For the temperature sensor 10, for example, a thermistor or the like can be used.

An inner pot 11 is arranged in the inner pot receiving portion 3 of the rice cooker body 1 so that it can be taken out. The inner pot 11 has a shoulder portion 3 of the inner pot accommodating portion 3 which has an upper opening edge portion 11a that spreads outward.
It is placed on a so that its body and bottom do not come into contact with the inner pot receiving portion 3.

The control device 12 receives input signals from the temperature sensor 10 and the rice cooking switch 13 and outputs control signals to the inverter circuit 8 and the display unit 14. The inverter circuit 8 supplies high-frequency current to the heating coils 6a and 6b by the switching element 7 according to the control signal, and induction-heats the inner pot 11.

Next, the rice cook reception process in the controller 12 of the rice cooker having the above construction will be described. It should be noted that the rice cooking process performed after the rice cooking acceptance process is the same as the conventional one, and thus the description thereof will be omitted.

That is, in this rice-cooking acceptance process, as shown in the flowchart of FIG.
It is determined whether or not there is an input signal from (step S1). If there is an input signal from the rice cooking switch 13, the temperature Tx detected by the temperature sensor 10 is the set temperature Th.
(For example, 50 ° C.) is determined (step S2). If the detected temperature Tx does not exceed the set temperature Th, even if the inner pan 11 is heated, it is determined that the temperature does not rise until the switching element 7 reaches heat loss, and therefore the rice cooking control is started.

In normal use, the heat sink 9
Since the switching element 7 is cooled to an appropriate temperature by the heat radiation effect of, there is no problem in use. However, when rice is continuously cooked, the heat radiating action of the heat sink 9 may not sufficiently cool the switching element 7. That is, if the detected temperature Tx exceeds the set temperature Th, it is determined that the switching element 7 will be damaged by heating the inner pot 11. Therefore, when the detected temperature Tx exceeds the set temperature Th, the reception of the input signal from the rice cooking switch 13 is rejected (step S3), and the fact that the rice cooking cannot be received is displayed on the display unit 14 (step S4). ). As a result, the heat loss of the switching element 7 is avoided, and the malfunction such that the switching element 7 cannot be used due to a failure does not occur. During this time, if the inverter circuit 8, particularly the switching element 7, is cooled via the heat sink 9 and the detected temperature Tx becomes lower than the set temperature Th, the rice cooking process is started as in the conventional case.

As described above, in the rice cooker, if it is determined that the temperature in the vicinity of the switching element 7 exceeds the predetermined temperature during rice cooking if the rice cooking process is started based on the temperature Tx detected by the temperature sensor 10, Since the acceptance of the input signal of the rice cooking switch 13 is rejected, the switching element 7 does not suffer heat loss.

In the above embodiment, the switching element 7 is naturally cooled, but the fan 15 (see FIG.
The middle and dotted lines are shown. ) May be provided for positive cooling. In this case, the provided fan 15 is downsized,
It is preferable to reduce wind noise and simplify the structure of the rice cooker so that it can be produced at low cost. However, even if the fan 15 provided is of a normal size, if the temperature Tx detected by the temperature sensor 10 exceeds the set temperature Th in continuous rice cooking, the rice which causes heat loss to the switching element 7 is cooked. It is effective in not starting.

When the temperature Tx detected by the temperature sensor 10 is higher than the set temperature Th, the time when rice cooking can be started may be estimated from the degree of decrease in the detected temperature Tx. That is, in general, the detected temperature Tx is the set temperature Th.
It is considered to be higher than this when there is a desire to cook rice early, such as when cooking rice continuously. Therefore, the estimated start time of cooking rice is displayed on the display unit 14. In this case, the previous rice cooking time may be stored, and the total of this rice cooking time and the time when rice can be started may be displayed as the time until the completion of rice cooking.

[0020]

As is apparent from the above description, according to the rice cooker of the present invention, when the temperature detected by the temperature detecting means exceeds the set temperature, the acceptance of the input signal from the rice cooking switch is rejected. As a result, the switching element will not be abnormally heated to cause heat loss.

Therefore, even if the structure without the fan is adopted, the rice cooker will not be damaged, the generation of wind noise during rice cooking can be prevented, and the rice cooker can be miniaturized and reduced in cost. .

[Brief description of drawings]

FIG. 1 is a schematic view of a rice cooker according to the present invention.

FIG. 2 is a flowchart showing a rice cooking reservation process in the rice cooker of FIG.

[Explanation of symbols]

 6a, 6b Heating coil 7 Switching element 8 Inverter circuit 10 Temperature sensor (temperature detection means) 11 Inner pan 12 Control device (control means) 13 Rice cooking switch 14 Display unit (display means)

Claims (4)

[Claims] 1. A heating coil for induction heating an inner pot, an inverter for supplying a high frequency current to the heating coil, a switching element for oscillating the inverter, and a rice cooking switch for starting the induction heating. In the rice cooker, temperature detecting means arranged in the vicinity of the switching element, and control means for rejecting an input signal from the rice cooking switch when the temperature detected by the temperature detecting means exceeds a set temperature. Rice cooker characterized by having. 2. The rice cooker according to claim 1, wherein the control means causes the display means to display an error when the temperature detected by the temperature detection means exceeds a set temperature. . 3. The control means, when the temperature detected by the temperature detecting means exceeds a preset temperature, stops energizing the heating coil until the temperature falls below the preset temperature. Rice cooker according to 1 or 2. 4. The control means estimates the time required until the temperature falls below a set temperature from the degree of decrease in the temperature detected by the temperature detection means, and causes the display means to display the time until the start of rice cooking. The rice cooker according to claim 3, wherein: