JP7133770B2 - rice cooker - Google Patents

Description

The present invention relates to a rice cooker.

Japanese Patent Laid-Open No. 2002-200001 discloses an overheating prevention device configured to bring a temperature fuse unit into contact with a heat-sensitive member that contacts a pan in order to prevent the temperature of cooking utensils such as rice cookers from rising excessively. ing.

JP-A-04-61823

However, with the technique of Patent Document 1, the temperature rise of the cooking utensil cannot be suppressed until the thermal fuse blows, so once the thermal fuse blows, the rice cooker cannot be used again unless the thermal fuse is replaced. . It is also conceivable to detect the temperature of the pot with a temperature sensor and control heating by a heating unit such as a heater according to the temperature detected by the control circuit. It becomes difficult for the circuit to accurately process the temperature sensed by the temperature sensor. Therefore, an abnormal temperature rise due to heating by the heater cannot be effectively suppressed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a rice cooker capable of effectively suppressing an abnormal temperature rise due to heating of a heating unit.

A rice cooker according to an aspect of the present invention includes a housing, a pot housed in the housing and containing rice and water to be cooked, and a pot disposed in the housing, wherein the a heating unit that heats the pan, a temperature detection unit that is arranged in the housing and detects the temperature of the pan, and energization of the heating unit based on the temperature of the pan detected by the temperature detection unit. and a cutoff unit that cuts off power supply to the heating unit based on the temperature of the pan detected by the temperature detection unit, wherein the control unit detects the temperature detected by the temperature detection unit. When the temperature of the pot becomes equal to or higher than the first temperature, the power supply to the heating unit is stopped, and the cutoff unit detects that the temperature of the pot detected by the temperature detection unit is higher than the first temperature. When the temperature reaches a second high temperature or higher, power supply to the heating unit is interrupted.

ADVANTAGE OF THE INVENTION The rice cooker which concerns on this invention can suppress effectively the abnormal temperature rise by the heating of a heater.

FIG. 1 is an external perspective view of a rice cooker according to an embodiment. FIG. 2 is an exploded perspective view of the rice cooker according to the embodiment. FIG. 3 is a schematic diagram for explaining the arrangement of main parts of the rice cooker according to the embodiment. FIG. 4 is a block diagram showing the main configuration of the rice cooker. FIG. 5 is a circuit diagram showing the configuration of the cutoff section. FIG. 6 is a flow chart showing an operation for suppressing excessive temperature rise by the control unit. FIG. 7 is a flow chart showing an operation for suppressing an excessive rise in temperature by the blocking section.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments described below are all comprehensive or specific examples. Numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, connection modes, and the like shown in the following embodiments are examples, and are not intended to limit the present invention. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in independent claims representing the highest concept will be described as arbitrary constituent elements.

Each figure is a schematic diagram and is not necessarily strictly illustrated. Moreover, in each figure, the same code|symbol is attached|subjected with respect to substantially the same structure, and the overlapping description may be abbreviate|omitted or simplified.

(Embodiment)
[Configuration of rice cooker]
In the present embodiment, as the rice cooker 1, an induction heating rice cooker that cooks rice by heating a pot by supplying a high-frequency current to a heating coil will be described as an example. Note that the rice cooker 1 may not be an induction heating type rice cooker, and may be, for example, a heater type rice cooker that heats a pot with an electric heater.

FIG. 1 is an external perspective view of a rice cooker 1 according to this embodiment. FIG. 2 is an exploded perspective view of rice cooker 1 according to the present embodiment. FIG. 3 is a schematic diagram for explaining the arrangement of main parts provided inside the rice cooker main body 20. As shown in FIG. FIG. 4 is a block diagram showing the main configuration of the rice cooker. 2, (a) shows the steam release part 40, (b) shows the outer lid 30, (c) shows the inner lid 60, (d) shows the pan 50, and (e) shows the rice cooker main body 20. . 3(b) is an enlarged view of the position near the center of the bottom surface of the pan 50 in FIG. 3(a).

The rice cooker 1 includes a housing 10, a pot 50, a heating section 24, a temperature detection section 26, a control section 71, and a cutoff section 74, as shown in these figures. Rice cooker 1 may further include thermal fuse 27 . Moreover, the rice cooker 1 may further include an AC-DC conversion section 80 and a power connection section 90 .

The housing 10 includes a rice cooker main body 20 and an outer lid 30, as shown in FIGS. The outer lid 30 is attached above the rice cooker main body 20 so as to be openable and closable. When the outer lid 30 is closed, the rice cooker body 20 and the outer lid 30 can be seen from the rice cooker 1 as shown in FIG. A handle 21 for carrying the rice cooker 1 is attached to the rice cooker main body 20 .

As shown in FIG. 2E, the rice cooker main body 20 has a pot accommodating portion 23 that accommodates a pot 50, which will be described later. The pot accommodating portion 23 has a recessed shape along the shape of the pot 50. - 特許庁In the pot accommodating portion 23, the bottom portion that contacts the bottom surface of the pot 50 and the side portion of the pot accommodating portion 23 that contacts the side surfaces of the pot 50 are made of, for example, a highly heat-resistant resin material.

The outer lid 30 is arranged above the rice cooker main body 20, as shown in FIGS. 1 and 2(b). The outer lid 30 is attached to the rice cooker main body 20 so as to be freely opened and closed by an outer lid attachment portion 22 provided on the rice cooker main body 20 . Further, the outer lid 30 is provided with an operating portion 31 and an open/close button 32 as shown in FIG. The operation unit 31 is a part that performs operations and displays such as, for example, starting rice cooking and selecting a rice cooking menu. The open/close button 32 is a button for opening the outer lid 30 . When the open/close button 32 is pressed, the outer lid 30 rotates about the outer lid mounting portion 22 with respect to the rice cooker main body 20 to open. On the contrary, the outer lid 30 is pressed toward the rice cooker main body 20 to rotate about the outer lid mounting portion 22 in the opposite rotational direction to the opening with respect to the rice cooker main body 20, thereby being closed. becomes.

1 and 2(a), a vapor release portion 40 is provided in a portion of the outer lid 30. As shown in FIG. The steam release part 40 is provided with a steam port 41, and steam is released from the steam port 41 during rice cooking. Also, the steam release part 40 can be removed from the outer lid 30 .

Furthermore, as shown in (c) and (d) of FIG. 2, the rice cooker 1 includes a pot 50 and an inner lid 60 inside the rice cooker surrounded by the rice cooker main body 20 and the outer lid 30. there is

The pan 50 is a container in which food to be cooked including rice and water is stored and cooked by being heated. The pan 50 is made of, for example, metal, metal-coated ceramics, or the like. The pot 50 is housed in the pot housing portion 23 provided in the rice cooker main body 20 .

The inner lid 60 is arranged on the surface of the outer lid 30 on the rice cooker main body 20 side, and seals the pot 50 by covering the upper opening of the pot 50 accommodated in the pot accommodating portion 23 . The inner lid 60 is provided with a pressure adjusting portion 61 that adjusts the pressure inside the pot 50 . The pressure adjustment unit 61 adjusts the pressure by adjusting the amount of water vapor inside the pot 50, for example. Unnecessary steam generated by the pressure adjustment of the pressure adjustment unit 61 is released to the outside of the rice cooker 1 from the steam port 41 of the steam release unit 40 .

The heating unit 24 is an electromagnetic coil for heating the pan 50 and causes electromagnetic induction by high-frequency current supplied from the control circuit 70 . Thereby, the pan 50 is induction-heated by the heating unit 24 . Note that the heating unit 24 is not limited to an electromagnetic coil for performing induction heating, and may be an electric heater that generates heat when energized.

The heating unit 24 has a first heating coil 24 a that heats the bottom surface of the pot 50 and a second heating coil 24 b that heats the bottom surface and the vicinity of the corners of the side surfaces of the pot 50 . The first heating coil 24 a is wound in an annular shape and arranged on the bottom surface of the pot housing portion 23 . The second heating coil 24b is wound around the corners of the bottom and side surfaces of the pan accommodating portion 23 . By heating the pot 50 with the first heating coil 24a, internal convection occurs inside the pot 50, in which heat rises from the center of the pot 50 and convects outward. In addition, by heating the pan 50 with the second heating coil 24b, an external convection occurs inside the pan 50, in which heat rises from the outside of the pan 50 and convects toward the center. By switching between the first heating coil 24a and the second heating coil 24b at high speed and repeating internal convection and external convection, the rice inside the pot 50 is vibrated and heat is uniformly conducted to the entire pot 50. be able to.

A container 25 in which a temperature detector 26 and a thermal fuse 27 are accommodated is arranged near the center of the lower bottom of the pan accommodating portion 23, as shown in FIG.

The temperature detection unit 26 is a temperature sensor arranged inside the container 25 and on the lower surface of the bottom surface of the pot housing unit 23 . The temperature detector 26 outputs an electrical signal indicating the detected temperature to the control circuit 70, as shown in FIG.

The thermal fuse 27 is arranged inside the container 25 and below the temperature detector 26 . The thermal fuse 27 is composed of two thermal fuses connected in series. Also, the thermal fuse 27 is configured to melt when the temperature reaches a third temperature (for example, 250° C.) higher than a second temperature (see below). The thermal fuse 27 is connected between the control section 71 and the power connection section 90, as shown in FIG. As a result, when the thermal fuse 27 is melted, the control unit 71 is not supplied with power from the power supply connection unit 90 . In other words, the thermal fuse 27 cuts off the power supply to the heating unit 24 when the temperature of the pan 50 reaches or exceeds the third temperature.

The control section 71 and the cutoff section 74 constitute a control circuit 70 as shown in FIG. The control circuit 70 may be formed on one substrate, or may be formed on two or more substrates.

The control unit 71 controls power supply to the heating unit 24 based on the temperature of the pan 50 detected by the temperature detection unit 26 . Specifically, the control unit 71 stops energizing the heating unit 24 when the temperature of the pot detected by the temperature detection unit 26 reaches or exceeds a first temperature (for example, 150° C.). The control unit 71 also controls the heating unit 24 for cooking rice based on the detection results detected by various sensors such as the temperature detection unit 26 . The control section 71 is composed of a microcomputer 72 and an inverter circuit 73 .

The microcomputer 72 is a microcomputer and has, for example, a processor and memory. The microcomputer 72 performs control of rice cooking, temperature control of the pan 50, etc. by executing a predetermined program stored in advance in the memory.

The inverter circuit 73 controls the high-frequency current supplied to the first heating coil 24a and the second heating coil 24b according to the control signal from the microcomputer 72. FIG. The inverter circuit 73 may adjust the magnitude of heating of the pan 50 by changing the energization ratio of the first heating coil 24 a and the second heating coil 24 b under the control of the microcomputer 72 . The current applied to the first heating coil 24a and the second heating coil 24b is obtained from an AC-DC conversion unit 80 that obtains a predetermined power from a power supply connection unit 90 connected to a power supply and generates a direct current. Via the control circuit 70, it is supplied to the first heating coil 24a and the second heating coil 24b.

The power connection unit 90 is, for example, an insertion plug connected to a household outlet. The power supply connection unit 90 may be connected to a commercial power supply, may be connected to a generator, or may be connected to a power storage device. In other words, the power supply connection unit 90 is not limited to an insertion plug as long as it can receive power supply by being electrically connected to each terminal of the power supply.

The cutoff unit 74 cuts off the power supply to the heating unit 24 based on the temperature of the pot 50 detected by the temperature detection unit 26 . Specifically, when the temperature of the pot 50 detected by the temperature detection unit 26 reaches or exceeds a second temperature (for example, 200° C.) higher than the first temperature, the cutoff unit 74 de-energize the Further, when the temperature of the pot 50 detected by the temperature detection unit 26 is higher than or equal to the second temperature and lower than the second temperature, the cutoff unit 74 restores the power supply to the heating unit 24 from the cutoff state.

Here, a detailed configuration of the blocking section 74 will be described.

FIG. 5 is a circuit diagram showing the configuration of the cutoff section 74. As shown in FIG.

The cutoff section 74 is composed of a comparator 75 and a cutoff circuit section 76 .

The comparator 75 has an input side connected to the reference voltage generation section 77 and the temperature detection section 26 and an output side connected to the cutoff circuit section 76 . The comparator 75 compares the reference voltage (eg, 5V) generated by the reference voltage generator 77 and the voltage output by the temperature detector 26 . Then, the comparator 75 outputs L when the voltage output from the temperature detection unit 26 is equal to or higher than the reference voltage, and outputs H when the voltage is less than the reference voltage.

The temperature detector 26 is set to output a voltage equal to or higher than the reference voltage when the temperature is equal to or higher than the second temperature, and to output a voltage lower than the reference voltage when the temperature is lower than the second temperature. Further, the temperature detecting section 26 outputs a higher voltage as the temperature detected by the temperature detecting section 26 increases.

The cutoff circuit section 76 is a switch that switches conduction or non-conduction of current from the inverter circuit 73 to the heating section 24 according to the output from the comparator 75 . The cutoff circuit unit 76 is arranged on the power line that connects the inverter circuit 73 and the heating unit 24 . The cutoff circuit unit 76 brings the inverter circuit 73 and the heating unit 24 into a non-conducting state when the comparator 75 outputs L, and disconnects the inverter circuit 73 and the heating unit 24 when the comparator 75 outputs H. is in a conducting state.

As a result, when the temperature of the pot 50 changes from less than the second temperature to the second temperature or higher, the cutoff unit 74 cuts off the power supply to the heating unit 24, and the temperature of the pot 50 changes from the second temperature or higher to the second temperature. If the temperature changes below the temperature of No. 2, the power supply to the heating unit 24 is restored.

[Operation of the rice cooker]
The operation of the rice cooker 1 will be described below.

FIG. 6 is a flow chart showing the operation of the control unit 71 for suppressing an excessive temperature rise.

As shown in FIG. 6, the control unit 71 determines whether or not the rice cooker 1 is cooking rice (S11). Then, it is determined whether or not the temperature of the pan 50 is equal to or higher than the first temperature (S12).

When the control unit 71 determines that the temperature of the pan 50 detected by the temperature detection unit 26 is equal to or higher than the first temperature (Yes in S12), the control unit 71 stops energizing the heating unit 24 (S13).

On the other hand, when the control unit 71 determines that the temperature of the pot 50 detected by the temperature detection unit 26 is lower than the first temperature (No in S12), the heating unit 24 is energized. If the power supply to the heating unit 24 has been stopped, the power supply to the heating unit 24 is resumed (S14).

If the control unit 71 determines in step S11 that the rice cooker 1 is not cooking rice (No in S11), it ends the operation for suppressing an excessive temperature rise. That is, when the rice cooker 1 finishes cooking rice, the control unit 71 finishes the operation for suppressing an excessive temperature rise.

FIG. 7 is a flow chart showing the operation of the cutoff unit 74 for suppressing an excessive rise in temperature. Note that the operation for suppressing an excessive temperature rise by the cutoff unit 74 is performed regardless of the operation of the control unit 71 as long as the power of the rice cooker 1 is on.

As shown in FIG. 7, the cutoff unit 74 determines whether or not the temperature is equal to or higher than the second temperature (S21). Cut off (S22). On the other hand, if the temperature is lower than the second temperature (No in S21), the cutoff unit 74 continues to energize the heating unit 24, or returns from the cutoff state of energization to the heating unit 24 (S23). .

[Effects, etc.]
Rice cooker 1 according to the present embodiment includes housing 10 , pan 50 , heating section 24 , temperature detection section 26 , control section 71 and cutoff section 74 . The pot 50 is accommodated in the housing 10 and accommodates food to be cooked including rice and water. The heating unit 24 is arranged in the housing 10 and heats the pan 50 . The temperature detection unit 26 is arranged in the housing 10 and detects the temperature of the pan 50 . The control unit 71 controls power supply to the heating unit 24 based on the temperature of the pan 50 detected by the temperature detection unit 26 . The cutoff unit 74 cuts off the power supply to the heating unit 24 based on the temperature of the pot 50 detected by the temperature detection unit 26 . The control unit 71 stops energizing the heating unit 24 when the temperature of the pan 50 detected by the temperature detection unit 26 becomes equal to or higher than the first temperature. The cutoff unit 74 cuts off the power supply to the heating unit 24 when the temperature of the pot 50 detected by the temperature detection unit 26 reaches or exceeds a second temperature higher than the first temperature.

In this way, when the temperature of the pot 50 becomes equal to or higher than the first temperature, the control unit 71 performs control to stop the energization of the heating unit 24, and the cutoff unit 74 controls the second temperature higher than the first temperature. When the temperature becomes equal to or higher than the temperature of the heating portion 24, the power supply to the heating portion 24 is cut off. Therefore, even if it becomes difficult for the control unit 71 to accurately process the temperature detected by the temperature detection unit, the cutoff unit 74 prevents the heating unit 24 from being energized when the temperature exceeds the second temperature. can be blocked. Therefore, an abnormal temperature rise due to heating of the heating portion 24 can be effectively suppressed.

Also, during cooking, when a film of starch is formed on the portion where the rice and water in the pot 50 are in contact with the pot 50, and the water between the pot 50 and the film boils, Gaps may occur between the film and the film. In this case, the portion of the pot 50 where the void is formed is in an empty state, and the temperature suddenly rises by several tens of degrees Celsius in a short time. Even in such a case, by setting the first temperature to a temperature lower than the temperature in a state where the temperature rises by several tens of degrees Celsius, the occurrence of a rapid temperature rise can be effectively suppressed. can be done.

Moreover, the rice cooker 1 according to the present embodiment further includes a temperature fuse 27 that cuts off the power supply to the heating unit 24 when the temperature of the pot 50 reaches a third temperature higher than the second temperature. . Therefore, even if the cutoff portion 74 cannot suppress an abnormal temperature rise due to the heating of the heating portion 24, the thermal fuse 27 cuts off the power supply to the heating portion 24 when the temperature reaches the third temperature or higher. can. Therefore, an abnormal temperature rise due to heating of the heating portion 24 can be effectively suppressed. The cutoff unit 74 cuts off the current to the heating unit 24 at a second temperature higher than the first temperature controllable by the control unit 71 and lower than the third temperature at which the thermal fuse 27 melts. That is, in many cases, the power supply to the heating unit 24 is interrupted before the thermal fuse 27 is fused, so that it is possible to reduce the shortening of the life due to exposure of the thermal fuse 27 to a high temperature. .

Moreover, in the rice cooker 1 according to the present embodiment, when the temperature of the pot 50 detected by the temperature detection unit 26 is higher than or equal to the second temperature and lower than the second temperature, the cutoff unit 74 stops the heating unit 24 to recover from the state in which the power supply to is cut off. Therefore, even if the control unit 71 cannot control the power supply to the heating unit 24 due to an abnormal temperature rise, the power supply to the heating unit 24 can be cut off without using a thermal fuse. If it drops, it can be restored.

Moreover, the numerical values, shapes, and materials used in the above-described embodiments are all examples for specifically describing the present invention, and the present invention is not limited to the numerical values, shapes, and materials exemplified.

As described above, the embodiments can be realized by various modifications that a person skilled in the art can think of, or by arbitrarily combining the constituent elements and functions of the embodiments and modifications without departing from the scope of the present invention. Forms are also included in the present invention.

INDUSTRIAL APPLICATION This invention is useful as a rice cooker etc. which can suppress effectively the abnormal temperature rise by the heating of a heater.

Reference Signs List 1 rice cooker 10 housing 20 rice cooker body 21 handle 22 outer lid mounting portion 23 pot housing portion 24 heating portion 24a first heating coil 24b second heating coil 25 container 26 temperature detector 27 temperature fuse 30 outer lid 31 operating portion 32 Opening/closing button 40 steam discharge unit 41 steam port 50 pot 60 inner lid 61 pressure adjustment unit 70 control circuit 71 control unit 72 microcomputer 73 inverter circuit 74 cutoff unit 75 comparator 76 cutoff circuit unit 77 reference voltage generator 80 AC-DC converter 90 power connection

Claims (3)

a housing;
a pot that is housed in the housing and houses food to be cooked including rice and water;
a heating unit that is arranged in the housing and heats the pot;
a temperature detection unit that is arranged in the housing and detects the temperature of the pot;
a control unit that controls energization of the heating unit based on the temperature of the pot detected by the temperature detection unit;
a cut-off unit that cuts off power supply to the heating unit based on the temperature of the pot detected by the temperature detection unit;
with
When the temperature of the pot detected by the temperature detection unit reaches a temperature range equal to or higher than a first temperature of 150° C. or more and less than 200° C., the control unit stops energizing the heating unit,
The first temperature is higher than the boiling state of water and lower than the empty boiling state that suddenly occurs in a short period of time when the object to be cooked is increased by several tens of degrees Celsius during cooking in the pot ,
When the temperature of the pot detected by the temperature detection unit reaches or exceeds a second temperature higher than the first temperature, the cutoff unit cuts off power supply to the heating unit.
rice cooker. moreover,
A thermal fuse that cuts off the power supply to the heating unit when the temperature of the pot reaches a third temperature higher than the second temperature,
The rice cooker according to claim 1. When the temperature of the pot detected by the temperature detection unit is equal to or higher than the second temperature and is lower than the second temperature, the cutoff unit restores the state in which the power supply to the heating unit is cut off. 3. The rice cooker according to item 1 or 2.

Images