JPH09252944A - Rice cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assuredly effect abnormality checking of a temperature sensor. SOLUTION: When a rice cooking switch is set to On at S1, a temperature comparator decides whether a difference between detected temperatures entered from a lid temperature detector and a pan temperature detector, respectively, exceeds a prescribed value or not at S2. If it is lower than the prescribed value, a combustion control section fires a gas burner and performs normal cooking control at S3. However, if it is higher than the prescribed value, the comparator understands that an abnormality has occurred in a thermister, and a command to sound a buzzer and to display an error message is issued. As a result, even if a shift error or fixed value error, not to mention of a disconnection or short circuit in the other sensor, these errors appearing as a temperature difference can be detected reliably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice cooker in which temperature sensors are provided on the lid side and the pot bottom side of a pot, respectively, and the rice cooker or the like is controlled by the detected temperatures obtained from the temperature sensors.

[0002]

2. Description of the Related Art A conventional rice cooker is disclosed in Japanese Patent Publication 7-10617.
As disclosed in Japanese Patent Publication No. 7, a temperature sensor (hereinafter referred to as a lid sensor) on the lid side of the pot for detecting the temperature of the upper portion of the pot,
It is equipped with a temperature sensor on the bottom of the pot that detects the temperature of the bottom of the pot (hereinafter referred to as the pot bottom sensor) .In the rice cooking sequence, the lid sensor detects the boiling state in the heating process after ignition of the gas burner. In the cooking or additional cooking process after boiling, the cooked bottom state is detected by the pot bottom sensor, and rice cooking control is performed according to these detected temperatures. As the temperature sensor, a thermistor is usually adopted, and the electric resistance value of the thermistor that changes depending on the temperature is used as the detected temperature.

[0003]

In the abnormality check of the thermistor itself used as the temperature sensor, the upper limit and the lower limit of the electric resistance value are set in advance, and the range is regarded as normal. It is checked that a short circuit has occurred. However, in the initial stage of the disconnection failure in the thermistor, there may occur a shift failure in which the change mode of the electric resistance value deviates from the original one, or a fixed value failure in which the electric resistance value does not change at a certain value. Since such an intermediate failure may occur even within the normal range, it has not been possible to deal with the disconnection and short circuit check by setting the upper and lower limits.

[0004]

Therefore, the present invention is based on the above 2
In a rice cooker using two temperature sensors, the temperature sensor can be checked for abnormalities reliably, and the configuration is such that the control unit that controls heating means such as a gas burner has a first temperature sensor It is characterized by comprising temperature comparison means for calculating a temperature difference between detected temperatures obtained from the second temperature sensor and judging that the temperature sensor is abnormal when the temperature difference reaches a predetermined value or more. It is a thing. Further, it is preferable that the calculation of the temperature difference and the abnormality determination are performed after the heating command is input to the control unit and before the operation of the heating means. Further, it is desirable that the calculation of the temperature difference and the abnormality determination are performed after a lapse of a predetermined time after the heating means is stopped. Further, it is desirable that the control unit is provided with an informing unit at the time of abnormality determination. Further, it is desirable to prohibit the operation of the heating means by the controller when the abnormality is judged.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a rice cooker.
The rice cooker 1 including the lid 2 and the inner pot 3 includes a gas burner 4
And three solenoid valves 5a to 5c arranged in the gas supply path.
Are provided respectively, and the solenoid valves 5a to 5c are opened / closed by the controller 6. Further, a detection signal of a lid sensor 7 provided on the lid 2 using a thermistor and a detection signal of a pot bottom sensor 8 provided on the pot bottom of the inner pot 3 also using a thermistor can be input to the controller 6. . An operation unit 9 is connected to the controller 6 and is equipped with a rice cooker and a heat retention switch. A reference numeral 10 is a display unit which is also connected to the controller 6 and displays operating states such as cooking rice and keeping heat, and 11 is an inner pot. 3 is a heater for keeping heat disposed around the periphery of the heater 3. Therefore, in the rice cooker 1, the controller 6 operates the ignition device (not shown) by the input operation of the rice cooker switch of the operation unit 9 and the solenoid valve 5 in the rice cooker 1.
The valves a to c are opened, the gas burner 4 is ignited, and the inner pot 3 is heated. Then, the lid sensor 7 detects boiling, and the bottom sensor 8 detects the cooked temperature.
5b is controlled to open and close to control the combustion of the gas burner 4 to cook rice based on a well-known rice cooking sequence. On the other hand, FIG. 2 is a functional block diagram of the controller 6, in which the electromagnetic control valves 5a to 5c are opened and the gas burner 4 is burned by the input operation of the rice cooker switch in the operation unit 9, and the heat retention is also maintained. Heat retention control unit 1 that operates the heat retention heater 11 by inputting a switch
3 is provided, and at the end of rice cooking, the heat retention control unit 13 operates the heat retention heater 11 by a signal from the combustion control unit 12. Reference numeral 14 is a timer control unit, and 15 is a temperature comparison unit, which receives a signal from the combustion control unit 12 or the heat retention control unit 13 via the timer control unit 14.
Are detected by the lid temperature detection unit 16 into which the electric resistance value of the lid sensor 7 is input as the detected temperature, and from the kettle bottom temperature detection unit 17 into which the electric resistance value of the kettle bottom sensor 8 is input as the detected temperature. Is entered. The temperature comparison unit 15 calculates the difference between the detected temperatures obtained from the both and compares it with a predetermined value. Further, as a notification means, the buzzer 18 can be sounded and an error can be displayed on the display unit 10.

The controller 6 constructed in this way is
When the rice cooking switch is turned on in the operation unit 9, it is possible to check whether the lid sensor 7 and the bottom sensor 8 are normal before the ignition operation of the gas burner 4. This check function will be described with reference to the flowchart of FIG. 3. When the rice cooking switch is turned on in S1, the temperature comparison unit 15 is input from the lid temperature detection unit 16 and the pot bottom temperature detection unit 17 respectively in the next S2. It is determined whether the difference in the detected temperature (electrical resistance value) is equal to or more than the predetermined value.
If it is less than the predetermined value, the combustion control unit 12 burns the gas burner 4 to execute normal rice cooking control in S3, but if it is more than the predetermined value, it is determined that an abnormality has occurred in the thermistor, and the buzzer is activated in S4. A command for ringing 18 and an error display on the display unit 10 is issued. Therefore, as described above, the lid sensor 7,
When the detected temperatures obtained by the bottom sensors 8 are compared with each other and the difference is used as a criterion for abnormality determination, when one of the sensors has a disconnection or a short circuit as well as the above-mentioned shift failure or fixed value failure. However, since they all appear as a temperature difference, these failures can be reliably detected. Further, by performing the above-mentioned abnormality check immediately after the input of the rice cooking switch, it is possible to prevent the user from cooking rice without knowing the failure of the temperature sensor. In the above description, the abnormality check is performed when the rice cooking switch is turned on, but the same abnormality check can be performed here when the heat retention switch is turned on.

Further, the above check is made by turning on the rice cooking switch.
In addition to immediately after the operation, it can be performed after a fixed time has elapsed after the completion of rice cooking and heat retention. That is, as shown in FIG. 4, it is first confirmed whether or not rice is being cooked in S1 (if rice is being cooked, S2 is directly
If rice cooking is completed, it is confirmed in S3 whether the temperature is being kept warm (if the temperature is being kept warm, the temperature is kept controlled in S4). If both the rice cooking and the heat retention are completed, the timer control unit 14 counts the elapse of a predetermined time (for example, 5 hours) from the end of the rice cooking and the heat insulation in S5, waits for the temperature decrease of the sensor, and the predetermined time elapses. , S6, the temperature comparison unit 15 detects the lid temperature detection unit 16 and the pot bottom temperature detection unit 1 as described above.
The difference between the detected temperatures (electrical resistance values) input from 7 and 7 is compared with a predetermined value or more, and
If it is equal to or more than the predetermined value, it is determined that the thermistor is abnormal, and the buzzer sounds and an error is displayed in S7. As described above, since the temperature sensor is operated by the rice cooking or the heat retention control (change in resistance value due to heating), the check is performed, so that the abnormality can be surely detected after the temperature is lowered.

Further, in the above abnormality check, only the abnormality is notified when the thermistor abnormality is detected. However, as shown in FIG. 5, after the abnormality is detected, the operation unit 9 is operated at S1.
Either the rice cooker switch or the heat retention switch is O
If the result is N, the temperature comparison unit 15 instructs the buzzer to sound and an error display in S2 and S3, and the combustion control unit 12 in S4.
Alternatively, it may be configured to output a rice cooking prohibition signal or a heat retention prohibition signal to the heat retention control unit 13. Therefore, in this case, even if the rice-cooking switch is pushed after the abnormality is detected, it is possible to forcibly prohibit the rice-cooking and the heat retention control to prevent the problem that the rice is cooked while the temperature sensor is still broken.

The temperature sensor may be checked for abnormality either after the rice is cooked or the heat retention switch is turned on, or after the rice cooking and the heat retention control are finished, but it is more reliable if performed at both timings. Become. In addition to the above buzzer or error display, other means such as blinking of a lamp or voice may be used as the notification means. In addition, considering the case where both temperature sensors are abnormal at the same time, the upper and lower limits of the electric resistance value are set in advance as described in the prior art, and the abnormality judgment when the range is exceeded is also adjusted. You can also do so.

[0010]

As described above, according to the present invention, the temperature difference between the detected temperatures obtained from the first and second temperature sensors is calculated, and this temperature difference is used as a criterion for the abnormality judgment. Of course, when a temperature detection shift failure, a fixed value failure, or the like occurs in the temperature sensor, it is possible to reliably deal with the failure, and a highly reliable abnormality check can be performed. If the calculation of the temperature difference and the abnormality determination are performed after the heating command is input to the control unit and before the operation of the heating means, the abnormality can be checked immediately before the operation of the heating means. Further, if the calculation of the temperature difference and the abnormality determination are performed after a lapse of a predetermined time after the heating means is stopped,
After the temperature of the heated temperature sensor has dropped, it is possible to reliably check for abnormalities. Further, if the control section is provided with a notification means at the time of abnormality determination, the abnormality of the temperature sensor can be surely notified. Further, when the control section prohibits the operation of the heating means when the abnormality is judged, it is possible to prevent the rice from being cooked while the temperature sensor remains abnormal.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a rice cooker.

FIG. 2 is a functional block diagram of a controller.

FIG. 3 is a flowchart of a temperature sensor abnormality check.

FIG. 4 is a flowchart of a temperature sensor abnormality check.

FIG. 5 is a flowchart of a rice cooking or heat retention prohibition function after abnormality determination.

[Explanation of symbols]

1 ... Rice cooker, 2 ... Lid, 3 ... Inner pot, 4 ... Gas burner, 5a-c ... Solenoid valve, 6 ... Controller, 7 ...
Lid sensor, 8 ... Kettle bottom sensor, 9 ... Operating part, 10 ...
Display unit, 12 ... Combustion control unit, 13 ... Heat retention control unit, 1
4 ・ ・ Timer control part, 15 ・ ・ Temperature comparison part.

Claims (5)

[Claims] 1. A first temperature sensor on the lid side of the kettle heated by a predetermined heating means for detecting the temperature of the upper portion of the inside of the kettle, and a bottom temperature of the kettle on the lid side of the kettle. A rice cooker provided with a second temperature sensor for detecting, according to the detected temperature obtained from each of the first and second temperature sensors, and a control section for controlling the heating means, In the control unit, the temperature difference between the detected temperatures obtained from the first temperature sensor and the second temperature sensor is calculated, and if the temperature difference reaches a predetermined value or more, it is determined that the temperature sensor is abnormal. A rice cooker having a temperature comparison means for 2. The rice cooker according to claim 1, wherein the calculation of the temperature difference and the abnormality determination are performed after a heating command is input to the control unit and before the operation of the heating unit. 3. The rice cooker according to claim 1, wherein the calculation of the temperature difference and the abnormality determination are performed after a lapse of a predetermined time after the heating means is stopped. 4. The rice cooker according to any one of claims 1 to 3, wherein the control unit is provided with an alarming means at the time of abnormality determination. 5. The rice cooker according to claim 1, wherein the control unit prohibits the operation of the heating unit when the abnormality is determined.