JPH10108785A - Induction heating type rice cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize optimum rice cooking without using a cooling fan. SOLUTION: An induction heating type rice cooker is provided with a heating coil 8 receiving the output of an inverter part 4, an internal pot 9 induction- heated by the heating coil 8, a temp. detection part 11 detecting the temp. of a switching element and an inverter driving part 13 driving the inverter part 4 by receiving the driving permission signal of the inverter from a control part 12. If the detected temp. is not less than a prescribed value when a rice cooking starting signal from a user is originated from a key input part 1 at the time, rice cooking is not started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice cooker used in ordinary households.

[0002]

2. Description of the Related Art In recent years, in order to pursue the taste of an electric rice cooker, an induction heating system using an inverter which can be expected to provide a strong fire effect has been taking over the place of the conventional sheathed heater system.

[0003]

However, an induction heating type rice cooker using an inverter has a structure in which a heat sink which is thermally coupled to prevent the switching element, which is a semiconductor element, from being destroyed due to thermal loss, is provided. It is necessary to cool the switching element by a fan motor via the fan, and there is a problem that a harsh sound is generated due to the rotation of the fan motor at the time of cooking rice. SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and provides a silent rice cooker without a cooling fan, without any trouble such as failure of rice cooking and destruction of a switching element, and without a harsh sound due to rotation of a fan motor. The purpose is to do so.

[0004]

In order to solve the above-mentioned problems, the present invention provides an inverter unit having a switching element, a heating coil receiving an output of the inverter unit, and an inner pot induction-heated by the heating coil. A temperature detection unit that detects the temperature of the switching element; and a control unit that controls driving of the inverter unit. The control unit is configured to control the inverter according to a comparison value between an output of the temperature detection unit and a set temperature. The drive of the unit is controlled.

[0005]

According to the first aspect of the present invention, the temperature of a switching element is monitored, and appropriate control of the inverter drive is performed in accordance with the temperature information. This means that trouble such as destruction of the element is eliminated.

According to the second aspect of the present invention, when the temperature of the switching element is higher than a predetermined temperature immediately before the start of rice cooking, the start of rice cooking is not accepted. That is, it is possible to eliminate such a trouble that the rice cooker fails due to the interruption.

According to the third aspect of the invention, the control of the inverter unit is stopped when the temperature reaches a predetermined temperature during the rice cooking process, so that the switching element can be prevented from being destroyed even in the case of an abnormality.

[0008]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the overall configuration of the present invention, wherein 1 is a unidirectional power supply comprising a commercial power supply 2 and a rectifying bridge 3, 4 is a smoothing circuit 5 for preventing power supply line noise due to switching, and resonance. An inverter unit including a capacitor 6 and a switching element 7; a heating coil 8 connected in parallel to the resonance capacitor 6 to receive an output of the inverter unit 4; an inner pot 9 induction-heated by the heating coil 8; A heat sink thermally coupled to the switching element 7 included in the unit 4; a temperature detection unit 11 for indirectly detecting the temperature of the switching element 7 via the heat sink 10; A controller for comparing the detected temperature from the controller with the set temperature to determine whether the inverter can be driven, 13
Is an inverter driving unit that drives the inverter unit 4 upon receiving an inverter driving permission signal from the control unit 12, and 14 is a key input unit that transmits a rice cooking start signal from the user to the control unit 12.

Next, the operation and operation of this configuration will be described. In FIG. 1, the operation of the induction heating method will be described first. When a driving signal is received from the inverter driving unit 13, the unidirectional power supply 1 formed by the commercial power supply 2 and the rectifying bridge 3 passes through the smoothing circuit 5 and the high frequency power is supplied to the inverter unit 4 including the resonance capacitor 6 and the switching element 7. And supplies a high-frequency current to the heating coil 8. Then, the inner pan 9 whose surface is formed of a magnetic material is heated by the principle of induction heating. Therefore, when the user inputs the rice cooking start signal from the key input unit 14, the control unit 1
2 monitors the temperature information from the temperature detection unit 11 and, if the rice cooking can be started, controls the inverter driving unit 13 according to a program incorporated in a microcomputer built in the control unit 12 to execute the rice cooking. It is a translation.

Here, the temperature detecting section 11 and the control section 12
Will be described in detail with reference to FIG.

In step 15, when a command to execute rice cooking is input from the key input unit 14, in step 16, the temperature detection unit 1 is operated.
1 is input to the control unit 12, and the magnitude is compared with the first set temperature θ1. If θ <θ1, the process proceeds to step 18 to start cooking rice. If θ> θ
If it is 1, the rice cooking is not started until θ <θ1, and the user is notified that the rice cooking is not accepted as in step 17. When the rice cooking is started, the control unit 12 outputs a control output to the inverter driving unit 13 according to the rice cooking process incorporated in the microcomputer of the control unit 12, drives the inverter, and heats the inner pot 9 by induction. Then, the detection temperature of the temperature detection unit 11 also rises according to the rice cooking process. Therefore, as in steps 19 and 20, whether the detection temperature does not exceed the second set temperature θ2 set lower than the destruction temperature of the switching element 7 or not. Continue cooking while judging. Then, it is determined in step 21 whether or not the rice cooking can be completed. In step 22, the rice cooking is completed. Here, if the detected temperature exceeds the second set temperature in step 19, the drive of the inverter is stopped as in step 23, and the magnitudes of the detected temperature and the second detected temperature are compared as in step 24. Then, the drive stop of the inverter is continued until θ <θ2. When θ <θ2, the process returns to step 20 and rice cooking can be continued.

FIG. 3 shows a case of continuous rice cooking.
It will be described based on. First, assuming that the first rice cooking starts at time t0 when the detected temperature is θ0 lower than the first set temperature θ1, and reaches the maximum temperature θ3 at time t1.
In one cooked rice, the detected temperature rises by Δθ from the temperature at the start. Then, when the first rice cooking is completed, the detected temperature gradually decreases, and the second rice cooking is started at time t2 when the first set temperature θ1 is reached, time t3
And the temperature difference between the starting temperature and the maximum temperature is also Δθ. If the first set temperature is set so that the maximum temperature θ4 is lower than the second set temperature θ2, as long as rice cooking is started at a temperature lower than the first set temperature, the maximum temperature will be the destruction of the switching element. That is, rice can be cooked without reaching the temperature.

[0014]

As described above, according to the first aspect of the present invention, since the temperature of the switching element is monitored and the inverter drive unit is appropriately controlled in accordance with the temperature information, a configuration without a cooling fan is provided. However, troubles such as failure of rice cooking and destruction of the switching element are eliminated.

According to the second aspect of the present invention, if the temperature of the switching element is higher than a predetermined temperature immediately before the start of rice cooking, the start of rice cooking is not accepted. Thus, it is possible to provide an induction heating type rice cooker free from such troubles that rice cooking is interrupted and rice cooking fails.

Further, according to the third aspect of the present invention, the control of the inverter unit is stopped when the temperature reaches a predetermined set temperature during the rice cooking process. It can provide a heated rice cooker, and its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of an induction heating rice cooker according to one embodiment of the present invention.

FIG. 2 is a flowchart of the induction heating type rice cooker.

FIG. 3 is a transition diagram of a detected temperature of a temperature detecting unit in a rice cooking process of the induction heating type rice cooker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Unidirectional power supply 4 ... Inverter part 8 ... Heating coil 9 ... Inner pot 11 ... Temperature detection part 12 ... Control part 13 ... Inverter drive part 14 ... Key input part

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor: Akira Aku 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] An inverter unit having a switching element, a heating coil receiving an output of the inverter unit, an inner pot induction-heated by the heating coil, a temperature detecting unit detecting a temperature of the switching element, A control unit for controlling the driving of the inverter unit, wherein the control unit controls the driving of the inverter unit according to a comparison value between the output of the temperature detecting unit and a set temperature. 2. The method according to claim 1, wherein the switching element has a first set temperature which is a temperature at which rice can be cooked so that the switching element is not thermally destroyed during the rice cooking process. 2. The induction heating rice cooker according to claim 1, wherein the start of rice cooking is prohibited when the temperature is higher than the temperature. 3. The control unit has a second set temperature which is a substantially limit temperature at which the switching element does not thermally break down, and the control unit drives the inverter unit when the temperature detected by the temperature detection unit reaches the second set temperature. The induction-cooked rice cooker according to claim 1 or 2, wherein the induction is prohibited.