JPH08458A - Rice cooker - Google Patents

Abstract

PURPOSE:To detect foreign matters in a side sensor system. CONSTITUTION:A rice cooker is provided with a pot 7 to house rice to be cooked, heating means 6 and 15 to heat the pot 7, a control means 10 to control the power of the heating means 6 and 15, a first temperature detection means 13a to detect the temperature of the side of the pot 7 and a second temperature detection means 13b to detect the temperature of a heating source 15 of the heating means 6 and 15. The second temperature detection means 13b checks a first detection temperature as specified to detect the presence of foreign matters between the pot 7 and the heating means 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice cooker, and more particularly to a rice cooker which is provided with a second temperature detecting means to detect foreign matter and the absence of a pot and to cook rice even when foreign matter is detected.

[0002]

2. Description of the Related Art In a so-called heating plate type rice cooker in which a pan is placed on a heating plate, a temperature sensor for pressing the bottom of the pan is provided at the center of the heating plate so that the bottom of the pan is pressed against the bottom. A sensor system is used. If foreign matter such as rice grains or dust is present between the pan and the heating plate, the heating plate will generate heat abnormally and the space between the heating plate and the pan will become hot. The temperature rises sharply compared to when there is no foreign matter. Conventionally, it has been determined that there is a foreign substance by detecting that the temperature detected by this temperature sensor has rapidly increased.

[0003]

In recent years, the temperature sensor is pressed against the side surface of the pan to flatten the bottom of the inner container to improve the appearance and facilitate cleaning, a so-called side sensor system. Rice cooker has been put to practical use. In this case, since the side sensor is separated from the heating plate, the temperature of the side sensor does not rise sharply even if rice is cooked with foreign matter interposed between the heating plate and the pan. For this reason, the side sensor type rice cooker cannot perform the foreign matter determination of the bottom sensor type.

It is an object of the present invention to provide a rice cooker capable of detecting foreign matter even if it is a side sensor type. It is another object of the present invention to provide a rice cooker that can cook rice even if foreign matter is detected, and a rice cooker that can detect the absence of a pot.

[0005]

[Means for Solving the Problems] To achieve the above object, according to the present invention, as described in claim 1, a pot for putting cooked rice, a heating means for heating the pot, and an electric power for the heating means are provided. Control means for controlling the temperature of the pot, a first temperature detecting means for detecting the temperature of the side surface of the pot, and a second temperature detecting means for detecting the temperature of the heat source of the heating means. The presence of foreign matter between the pan and the heating means is detected by detecting the first detected temperature of. If a foreign substance is present between the pan and the heating means, the heat conduction from the heating means to the pan will not be performed effectively, and the heating means will generate abnormal heat. The second temperature detecting means for detecting the temperature of the heat source of the heating means follows the abnormal heat generation of the heating means. Therefore, the second
When the temperature detected by the temperature detecting means reaches a predetermined first detected temperature, the presence of foreign matter between the pan and the heating means is detected.

When detecting the presence of foreign matter, the control means sets a duty ratio, which is the ratio of the heating time to the stop time, and the first temperature detecting means sets a predetermined second value. The heating means may be controlled at the duty ratio until the detected temperature is detected. Thereby, even if there is a foreign substance, the control means controls the heating means to start cooking rice, and when the first temperature detecting means detects the predetermined second detected temperature, the rice is cooked.

Here, as described in claim 3, it is possible to stop the heating when the second temperature detecting means detects the predetermined third detected temperature while controlling the heating means. As a result, depending on how the foreign matter is inserted,
Even if the set duty ratio is too high and the heating means has a high temperature, the heating is stopped when the temperature exceeds the third detected temperature.
It does not affect the surrounding electric parts or the main unit.

According to another aspect of the present invention, as described in claim 4, a pan in which the cooked rice is put, a heating means for heating the pan, a control means for controlling electric power of the heating means, and a side surface of the pan. A first temperature detecting means for detecting a temperature, and a second temperature detecting means for detecting a temperature of a heat source of the heating means, wherein the second temperature detecting means detects a predetermined fourth detected temperature in a preheating step. I tried to detect the absence of pan. As a result, when heated without the pan, the heating means generates heat more abnormally than when foreign matter is present. The second temperature detecting means for detecting the temperature of the heat source of the heating means follows the abnormal heat generation of the heating means. Therefore, when the temperature detected by the second temperature detecting means reaches the predetermined fourth detected temperature, the absence of the pan is detected.

Further, as described in claim 5, in the preheating step, the absence of the pan may be detected depending on whether the temperature increase rate of the temperature detected by the second temperature detecting means is a predetermined value or more. Good. In the state without the pan, the temperature rise rate of the temperature detected by the second temperature detecting means becomes larger due to the abnormal heat generation of the heating means than in the case with the pan. Therefore, the absence of a pan is detected by this temperature increase rate. In the above invention, as described in claim 6, it is preferable that the second temperature detecting means is attached to a heat shield plate provided below the heat source. According to this, since the heat generated from the heat source is transmitted to the heat shield plate, the temperature detected by the second temperature detecting means attached to the heat shield plate accurately follows the temperature of the heat source. Therefore, the second temperature detecting means can detect the accurate temperature of the heat source.

[0010]

Next, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a rice cooker according to the present invention, which is composed of a container body 1 and a lid 2. Container body 1
Is roughly composed of an outer case 3, a bottom 4, an inner case 5, a heating plate 6, and a pot 7. A shoulder portion 8 extends inward at the upper end of the outer case 3. A display operation panel 9 is provided on the upper front surface of the outer case 3, and a control board including a liquid crystal display, switches, a power supply circuit, and a microcomputer is provided on the back side of the display operation panel 9, that is, inside the outer case 3. 1
0 is attached. Inside the outer body 3, four heating plate fixing columns 11 are provided so as to project downward from the shoulder portion 8.

The bottom 4 is fitted to the lower end of the outer case 3 to cover the outer case 3 from below. The inner body 5 has a cylindrical shape, and its upper end is brought into contact with the shoulder portion 8 of the outer body 3,
The lower end is adapted to come into contact with the outer peripheral edge of the heating plate 6.
A body heater 12 is arranged on the outer periphery of the upper portion of the inner body.
Below the inner case 5, a side sensor 1 including a thermistor is provided.
A sensor holder 14 holding 3a is attached. The side sensor 13a is biased toward the inner side of the inner case 5 by a coil spring (not shown), and comes into pressure contact with a side surface near the bottom of the pan 7 when the pan 7 is housed in the inner case 5. ing.

The heating plate 6 is formed by integrally molding the rice cooking heater 15 which is a sheathed heater, and the upper surface thereof is convexly curved so as to match the bottom surface of the pan 7. Heating plate 6
The lower end of the inner case 5 is placed on the outer peripheral edge of the. Eight legs 16 are provided near the outer periphery of the lower surface of the heating plate 6.
Is provided, and two bosses 17 project from the center. Reference numeral 18 denotes a heat shield plate, which is applied to the leg 16 of the heating plate 6 from below and is attached by screwing a mounting screw 19 into the boss 17. A bottom sensor 13b including a thermistor is attached to the heat shield plate 18.

As described above, the heating plate 6 and the inner case 5 which are integrated with the heat shield plate 18 are fixed from the outside of the bottom 4 with the fixing screw S.
By being screwed onto the tip of the fixing column 11, it is firmly held by the shoulder portion 8 and the bottom 4 of the outer case 3 via the heat shield plate 18. On the other hand, the lid body 2 is attached to the container body 1 so as to be openable and closable with the hinge shaft 20 as a fulcrum. Inside the lid, a heat radiating plate 22 having a lid packing 21 on the outer periphery is attached. A lid heater 23 and a lid sensor 24 including a thermistor are provided on the upper surface of the heat dissipation plate 22.

FIG. 2 shows an electric circuit of the rice cooker. The rice cooking heater 15 and the body heater 12 are connected in series and connected to an AC power supply 26 via a triac 25. An intermediate point between the rice cooking heater 15 and the body heater 12 is bypass-connected to a power source 26 via a relay 27. The lid heater 23 is also connected to the power supply 26 via the triac 28. On the other hand, the side sensor 13a is connected to the Vcc line.
Are connected via a resistor 29, similarly the lid sensor 24 is connected via a resistor 30, and the bottom sensor 13b is connected via a resistor 32.

The partial pressure between the side sensor 13a and the resistor 29, the partial pressure between the lid sensor 24 and the resistor 30, and the partial pressure between the bottom sensor 13b and the resistor 32 are the pan 7, the radiator plate 22, and the shield, respectively. It is input to the microcomputer 31 as a temperature detection signal of the heating plate 18. The heat generated by the rice cooking heater 15 is transferred to the heat shield plate by heat conduction through the legs 16 and the bosses 17 of the heat plate 6 or convection or radiation in the space between the heat plate 6 and the heat shield plate 18, The temperature detected by the sensor 13b corresponds to the temperature of the heat source. The microcomputer 31 executes a program stored in advance in its memory, the relay 27 and the triac 25,
An operation signal is output to 28 to cook rice.

The rice cooking process of the rice cooker in this embodiment will be described below with reference to the flow charts of FIGS. FIG. 3 shows the entire rice cooking process of the rice cooker, and FIG. 9 shows temperature changes of the side sensor 13a and the bottom sensor 13b in the normal rice cooking process. When the rice cooking switch is turned on, first, in step 101, only the body heater 12 is energized for 1 minute to perform preheating 1. Next, in step 102, preheating 2 is performed by energizing the rice cooking heater 15 and the body heater 12 at a predetermined duty ratio until the side sensor 13a detects a predetermined preheating temperature. Further, in step 103, the preheating temperature is maintained for a predetermined time by the on / off control of the rice cooking heater 15 to preheat 3
I do.

Subsequently, in steps 1 to 3 of steps 104 to 106, the rice cooking heater 15 is energized with full power to boil the cooked food, and in steps 107 and 108 of power control 1 and 2, power is supplied. It is dropped to maintain the boiling state for a predetermined time, and in step 109, heating is continued until the side sensor 13a detects a predetermined boiling temperature after the water in the pan is exhausted.

Next, in step 110, the rice cooking heater 15
Is turned off, the lid heater 23 is turned on, and the heat radiation plate 22 is maintained at a constant temperature, and the unevenness 1 is performed for a predetermined time. Step 1
In No. 11, while maintaining the heat dissipation plate 22 at a constant temperature, the rice cooking heater 15 is energized at a predetermined duty ratio to cook twice for a predetermined time. Then, in step 112, while turning off the rice cooking heater 15 and maintaining the heat dissipation plate 22 at a constant temperature,
Perform Murashi 2 for a predetermined time. Preheating 1 in the above rice cooking process
From the preheat to the preheat 3, both the foreign substance check and the pan-less check described below are performed, and the foreign substance check is performed from the middle pappa 1 to the cooked rice.

FIG. 4 shows a foreign substance check flow. This flow is executed in each of the steps from preheating 1 in step 101 to cooking in step 109 in the rice cooking step. That is, in step 201, it is determined whether or not the bottom sensor 13b has detected the predetermined first detected temperature T ₁ ° C. If it is lower than the first detection temperature T ₁ ° C, the program returns to the normal program of the rice cooking step, and if it is higher than the first detection temperature T ₁ ° C, the foreign matter rice cooking step is started in step 202. The first detected temperature is the temperature of the heat shield plate 18 at the mounting position of the bottom sensor 13b when foreign matter is present between the pan 7 and the heating plate 6 and the heating plate 6 is generating heat abnormally. . Therefore, it differs depending on the mounting position of the bottom sensor 13b. FIG.
The temperature is about 138 ° C. when attached to the position.

FIG. 5 shows a first embodiment of the foreign matter rice cooking process.
In step 301, the rice cooker heater 15 has a duty ratio of 20.
The power is turned on at / 30, and at step 302, the foreign matter cooking timer is started. Then, in step 303, it is determined whether the temperature detected by the lid sensor 24 is 120 ° C. or higher, and 1
If the temperature is lower than 20 ° C., the lid heater 23 is energized at a duty ratio of 30/30 in step 304, and if the temperature is 120 ° C. or higher, the lid heater 23 is turned off and the heat dissipation plate 22 of the lid 2 is turned to 120 °.
Keep at ℃. Next, in step 306, the side sensor 1
The temperature detected by 3a is the second detection temperature T ₂ ° C (for example, 1
15 ° C) or higher.

If the temperature is lower than T ₂ ° C, step 30
In step 7, it is judged whether or not 40 minutes have passed from the start of the foreign matter rice cooking process, and if it has not elapsed, the process returns to step 303 to continue the rice cooking process. If the temperature detected by the side sensor 13a is equal to or higher than the second detected temperature T ₂ ° C in step 306, it means that the temperature has already been cooked. Further, if 40 times have passed from the start of the foreign matter rice cooking process in step 307, the process proceeds to step 308 even if the foreign matter rice cooking process has not been cooked yet, and the unevenness one process is executed.

In this foreign matter cooking step, as shown in FIG. 10, when the temperature detected by the bottom sensor 13b becomes equal to or higher than T ₁ at time t _a and the foreign matter is detected, the foreign matter is cooked even if the foreign matter is present. Power and cooking temperature are set, the rice cooking heater 15 and the lid heater 23 are energized, and the side sensor 13
The energized state is continued until “a” detects a predetermined cooked temperature or 40 minutes elapse. Therefore, rice can be cooked as it is even if foreign matter is present.

FIG. 6 shows a second embodiment of the foreign matter rice cooking process.
In step 401, the rice cooking heater 15 is set to a duty ratio of 20.
The power is turned on at / 30, and the foreign rice cooking timer is started at step 402. Then, in step 403, it is determined whether the temperature detected by the lid sensor 24 is 120 ° C. or higher, and 1
If the temperature is lower than 20 ° C., the lid heater 23 is energized with a duty ratio of 30/30 in step 404, and if the temperature is 120 ° C. or higher, the lid heater 23 is turned off and the heat dissipation plate 22 of the lid 2 is turned to 120.
Keep at ℃. Next, in step 406, the side sensor 1
The temperature detected by 3a is the second detection temperature T ₂ ° C (for example, 1
15 ° C) or higher.

If the temperature is lower than T ₂ ° C, step 40
In step 7, it is determined whether 40 minutes have passed since the start of the foreign material rice cooking process. If not, in step 409, the temperature detected by the bottom sensor 13b is the third detection temperature T ₃ (for example, 1
40 ° C.) or higher. If the temperature is lower than the third detected temperature T ₃ , the process returns to step 403 to continue the rice cooking process.

If the temperature detected by the side sensor is equal to or higher than the second detected temperature T ₂ ° C. in step 406, it has already been cooked, and therefore the step 1 of step 408 is performed. In addition, if 40 times have passed from the start of the foreign matter rice cooking process in step 407, the process proceeds to step 408 even if the foreign matter rice cooking process has not been cooked, and the unevenness 1 process is executed. further,
If the temperature detected by the bottom sensor 13b is equal to or higher than the third detected temperature T _{3 in} step 409, in step 410 the rice cooker 1
5 and the lid heater 23 are both turned off, and the process returns to step 406.

In this foreign matter cooking step, as shown in FIG. 11, the temperature detected by the bottom sensor 13b becomes T ₁ ° C or higher at time t _a and the foreign matter is detected and the foreign matter cooking step is started. 6 heats up, the heat shield plate 18 becomes hot, and the bottom sensor 1
Even if the detection temperature of 3b is about to rise further, when the detection temperature of the bottom sensor 13b becomes equal to or higher than T ₃ at time t _b and t _c , the rice cooking heater 15 and the lid heater 23 are turned off. Therefore, the heating plate 6 and the heat shield plate There is no thermal effect on the electrical components and the body around 18.

FIG. 7 shows a first embodiment of the flow of the pan-less check, and this check is executed in the preheating steps 1, 2, and 3. In step 501, it is determined whether or not the current process is the preheating process 1, 2, or 3, and if so, it is determined in step 502 whether the temperature detected by the bottom sensor 13b is the fourth detection temperature T ₄ or higher. to decide. 4th detection temperature T ₄
If less, check ends and returns to the original rice cooking program. If the temperature is equal to or higher than the fourth detected temperature T ₄ , the buzzer is notified in step 503 to prompt the user to install the pan 7, and the rice cooking is stopped in step 504. Heating plate 6 and pan 7
When rice is cooked in a state where the rice is not placed, that is, in a state where the rice is not cooked, as shown in FIG.
When the temperature detected by 3b suddenly rises and the temperature detected by the bottom sensor 13b reaches the fourth detected temperature T ₄ at time t, the buzzer sounds and rice cooking automatically stops, which is safe.

FIG. 8 shows a second embodiment of the flow of the pan-less check, and this check is also executed in the preheating 1, 2, and 3 steps. In step 601, the bottom sensor 13
It is determined whether the temperature increase rate of the detected temperature by b is 10 ° C./30 seconds or more. And the temperature rise rate is 10
If the temperature is less than 30 seconds, the check is terminated and the original rice cooking program is returned to. If the temperature rise rate is 10 ° C./30 seconds or more, the buzzer is notified in step 602 to prompt the user to install the pan, and in step 603, the rice cooking is stopped. In this flow, the bottom sensor 13 as in the above embodiment is used.
b does not detect the absence of the pan by detecting the fourth detected temperature T ₄ , but the temperature rise ΔT (10 ° C.) within a constant time interval t _s (30 seconds) is observed as shown in FIG. is there.

The mounting position of the bottom sensor 13b is the heat shield plate 18
Any of the above may be used, but it is preferable that the heat source, that is, the rice cooker heater 15 is located as close as possible. Further, as shown in FIG. 1, the heat shield plate 18 may be directly attached, but the heat shield plate 18
Alternatively, a metal fitting may be attached to the metal fitting and the bottom sensor 13b may be fixed to the metal fitting so as to be close to the rice cooking heater 15 or directly attached to the heating plate 6.

[0030]

As is apparent from the above description, according to the first aspect of the present invention, the temperature of the heat source of the heating means is detected by the second temperature detecting means. Even if the temperature detecting means is a so-called side sensor type, foreign matter between the pan and the heating means is effectively detected.

In addition to this, according to the invention of claim 2, even if there is a foreign substance between the pot and the heating means, the control means controls the heating means to supply electric power in that state. , There is no power shortage as in the past, and the proper rice is cooked. Further, according to the invention of claim 3, no matter how the foreign matter is interposed, the heating is stopped when the temperature of the heat source becomes equal to or higher than the third detection temperature. Therefore, due to abnormal heating of the heating means, only the bottom is burnt. It does not burn or affect the surrounding electrical parts or the body.

Further, according to the inventions of claims 4 and 5, since the temperature of the heat source of the heating means is detected by the second temperature detecting means, the first temperature outputting means for detecting the temperature of the pot is so-called. Even with the side sensor method, the absence of a pan is effectively detected. Further, according to the invention of claim 6, the second temperature detecting means is attached to the heat shield plate provided below the heating means, and the heat source of the heating means is transferred to the heat shield plate by heat conduction. Can be accurately detected.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a rice cooker according to the present invention.

FIG. 2 is an electric circuit diagram of the rice cooker shown in FIG.

FIG. 3 is a flowchart of a rice cooking process.

FIG. 4 is a flowchart of foreign matter check.

FIG. 5 is a flowchart of a first embodiment of a foreign matter rice cooking process.

FIG. 6 is a flowchart of a second embodiment of a foreign matter rice cooking process.

FIG. 7 is a flowchart of a first embodiment of a pan-less check.

FIG. 8 is a flow chart of a second embodiment of a pan-less check.

FIG. 9 is a diagram showing changes in sensor temperature and power in a normal case.

FIG. 10 is a diagram showing a change in sensor temperature when the flow of FIG. 5 is executed when a foreign substance is present.

FIG. 11 is a diagram showing changes in sensor temperature when the flow of FIG. 6 is executed when a foreign substance is present.

FIG. 12 is a diagram showing changes in the sensor temperature when there is no pan and when there is a pan.

[Explanation of symbols]

 6 ... Heating plate (heating means), 7 ... Pan, 10 ... Control board (control means), 13a ... Side sensor (first temperature detecting means), 13b ... Bottom sensor (second temperature detecting means), 15 ... Rice cooking heater (Heating means), 18 ... Heat shield plate, 31 ... Microcomputer (control means).

Claims (6)

[Claims] 1. A pot for putting cooked rice, heating means for heating the pot, control means for controlling electric power of the heating means, first temperature detecting means for detecting a temperature of a side surface of the pot, and Second temperature detecting means for detecting the temperature of the heat source of the heating means, and the second temperature detecting means detects the presence of foreign matter between the pan and the heating means by detecting a predetermined first detected temperature. Rice cooker that is characterized by 2. A pot for putting cooked rice, heating means for heating the pot, control means for controlling electric power of the heating means, first temperature detecting means for detecting a temperature of a side surface of the pot, and A second temperature detecting means for detecting the temperature of the heat source of the heating means, wherein the second temperature detecting means detects the presence of a foreign substance between the pan and the heating means by detecting a predetermined first detected temperature; The control means sets a duty ratio, which is the ratio of the heating time to the stop time, and controls the heating means with the duty ratio until the first temperature detecting means detects a predetermined second detected temperature, and cooks up. Rice cooker characterized by that. 3. A pot for putting cooked rice, heating means for heating the pot, control means for controlling electric power of the heating means, first temperature detecting means for detecting a temperature of a side surface of the pot, and A second temperature detecting means for detecting the temperature of the heat source of the heating means, wherein the second temperature detecting means detects the presence of a foreign substance between the pan and the heating means by detecting a predetermined first detected temperature; The control means sets a duty ratio, which is the ratio of the heating time to the stop time, controls the heating means at the duty ratio until the first temperature detecting means detects a predetermined second detected temperature, and during the meantime, 2. A rice cooker characterized in that heating is stopped when the temperature detecting means detects a predetermined third detected temperature. 4. A pot for putting cooked rice, heating means for heating the pot, control means for controlling electric power of the heating means, first temperature detecting means for detecting a temperature of a side surface of the pot, and A second temperature detecting means for detecting the temperature of the heat source of the heating means, and the second temperature detecting means detects a predetermined fourth detected temperature in the preheating step to detect the absence of the pan. Rice cooker. 5. A pan for putting cooked rice, a heating means for heating the pan, a control means for controlling electric power of the heating means, a first temperature detecting means for detecting a temperature of a side surface of the pan, A second temperature detecting means for detecting the temperature of the heat source of the heating means, and detecting the absence of a pan by the preheating step depending on whether the temperature increase rate of the temperature detected by the second temperature detecting means is a predetermined value or more. Rice cooker characterized by doing so. 6. The rice cooker according to claim 1, wherein the second temperature detecting means is attached to a heat shield plate provided below the heat source.