JPH0441006B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a rice cooking jar equipped with a temperature sensor, and more particularly to a rice cooking jar equipped with a temperature sensor that can accurately detect the internal temperature of an inner pot.

<Prior Art> In a conventional rice cooker, a configuration is adopted in which a temperature sensor is attached to the outer surface or the center of the lower surface of the inner pot in order to detect the internal temperature of the inner pot. In rice cookers with a built-in microcomputer that have become popular in recent years, the temperature information detected by this temperature sensor is used as input.
It determines the amount of rice to be cooked, controls the rice cooking power, etc.

Therefore, the temperature sensor must be able to accurately detect the temperature of the rice or rice inside the inner pot, but in rice cookers, a heat-retaining heater is usually installed so that it is in contact with the outer surface of the inner pot. Since the rice cooking heater is attached to the bottom surface of the inner pot, if the temperature sensor is attached to the outer surface or the center of the bottom surface of the inner pot, it will be directly affected by the heat generated by the heat retention heater or the rice cooking heater. As it is, the temperature of the rice or rice inside the inner pot cannot be accurately detected. In order to solve such problems, it is necessary to compensate for the temperature detected by the temperature sensor by taking into account the direct influence of the heat generated by each heater, but it is necessary to compensate for the dimensional errors of the inner pot, each heater, etc. Because variations in sensor mounting positions affect each other, it is not possible to perform accurate temperature compensation, and furthermore, it is not possible to perform accurate temperature compensation over a temperature range of 100-odd degrees from room temperature. Become.

Therefore, in conventional rice cooking jars, rice cooking and warming operations are performed after acknowledging the above-mentioned error in detected temperature, and further improvements have been desired.

<Objective> The present invention has been made in view of the above-mentioned demands, and an object thereof is to provide a rice cooker with a temperature sensor that can detect the internal temperature of the inner pot extremely accurately.

<Structure> In order to achieve the above object, the present invention provides a hanging pin that projects downward from the lower surface of the outer lid, and the lower end of the hanging pin is fitted to the inner pot lid. In a rice cooker equipped with a temperature sensor in which the lid is detachably suspended, the lower end of the suspension pin faces into the inner pot, and the temperature sensor is attached to the lower end by being thermally connected to the atmosphere inside the inner pot. It is characterized by this.

<Examples> Hereinafter, examples will be described in detail with reference to the accompanying drawings showing examples.

FIG. 1 is a partially cutaway side view of the rice cooking jar.

1 is the rice cooker body, 2 is the inner pot,
2a is an inner pot lid, 3 is an inner pot storage container that accommodates the inner pot 2, 4 is a rice cooking heater, 5 is a center thermometer for detecting the end of rice cooking that is in contact with the lower surface of the inner pot 2, and 5a is a temperature sensor for detecting the internal temperature of the inner pot 2, 6 is a control unit incorporating a microcomputer, etc., 7 is a rice cooking switch, 8 is a heat-retaining heater, and 9a is a lower wall of the outer lid 9. 10 is a lid heater, and 11 is a hanging pin for attaching the inner pot lid 2a.

As shown in FIG. 2, the above-mentioned hanging pin 11 includes a cylindrical portion 11a into which the inner pot lid 2a is fitted;
The cylindrical portion 11a is comprised of a large-diameter stopper portion 11b fixed by screwing or the like to the tip of the cylindrical portion 11a, and the upper end of the cylindrical portion 11a is fixed to the center portion of the outer lid lower wall 9a. The cylindrical portion 11a is made of a material with low thermal conductivity such as plastic or silicone rubber, and the stopper portion 11b is made of a material with high thermal conductivity such as aluminum.
The stopper part 11b is located at the lower part of the inner pot lid 2a to prevent the inner pot lid 2a from coming off, and the inside thereof is hollow.

Further, a temperature sensor 5a for detecting the internal temperature of the inner pot 2, which is composed of a thermistor or the like, is connected to the stopper portion 1.
1b is provided in the hollow part, and its lead wire 5b passes through the cylindrical part 11a and is taken out to the outside, and a heat-insulating seal 5c is inserted into the upper end of the cylindrical part 11a, which is the outlet. .

In this way, a hanging pin 11 is provided that projects downward from the lower surface of the outer lid 9, and the lower end of this hanging pin 11 is fitted to the inner pot lid 2a to detachably suspend the inner pot lid 2a. In the rice cooking jar equipped with a temperature sensor, the lower end of the hanging pin 11 is made to face inside the inner pot 2, and the temperature sensor 5a is attached to the lower end by thermally connecting it to the internal atmosphere of the inner pot. 2 internal temperature can be detected very accurately and with good sensitivity.

The inner pot lid 2a is fitted onto the suspension pin 11 via an annular bushing 2b made of plastic, rubber, or the like, and is constantly pushed downward by an annular elastic ring 2c.

Next, the temperature sensor 5 for detecting the internal temperature of the inner pot 2
Determination of the rice cooking amount and rice cooking power control of the rice cooking jar 1 configured as shown in FIG.

Figure 3 is a rice cooking temperature curve showing temperature changes in the inner pot 2. The area shows the water absorption process in which the rice absorbs water by reducing the rice cooking power, and the area shows the rapid temperature rise, boiling, and boiling by increasing the rice cooking power. The area shows a cooking process in which hot water is maintained, and the region shows an uneven process in which the rice cooking power is reduced to zero. As a result of the experiment, if the time required for the temperature of the rice in the inner pot 2 to rise from about 40°C to 100°C is within the range of about 10 to 11 minutes, It has been found that delicious rice can be cooked without much uneven cooking between the top and bottom of the rice. Therefore, the temperature of the rice in inner pot 2 is approximately
In order to satisfy this requirement, it is necessary to configure the rice cooker so that the rice cooking operation can be performed along a rice cooking temperature curve in which the time required for the temperature to rise from 40°C to 100°C is within the range of approximately 10 to 11 minutes. In addition, the electrical components shown in FIG. 4 are incorporated into the rice cooker main body.
In the same figure, 12 is a microcomputer having a CPU, RAM, ROM, etc., and also has an A/D conversion function.
is memorized in advance. A temperature sensor 5a for detecting the internal temperature of the inner pot 2 and a center thermometer 5
By directly applying the temperature information obtained from the microcomputer 12 to the input port of the microcomputer 12, the temperature information as analog data can be converted into digital data. Further, the rice cooking switch 7 is connected to the microcomputer 12. Further, the energization amount control means 13 comprising a triax and the like and the rice cooking heater 4 are connected between both terminals of the commercial AC power supply 14, and the control signal from the output port of the microcomputer 12 is applied to the gate terminal of the energization amount control means 13. Connected.

Furthermore, the operation of the rice cooker configured as above will be explained.

When a desired amount of rice and an appropriate amount of water are put into the inner pot 2 and the rice cooking switch 7 is turned on, rice cooking starts according to the procedure of the rice cooking program stored in the ROM in the microcomputer 12. In the early stages of rice cooking, the rice cooking power is reduced to allow the rice to absorb water. After the rice absorbs water and the internal temperature of the inner pot reaches a predetermined temperature indicating completion of water absorption (the lower limit temperature of the temperature range for detecting the amount of cooked rice), the amount of cooked rice is determined according to the program procedure shown in Figure 5. Detection is performed.

After the water absorption step is completed, the rice cooking heater 4 is energized in a step, and the time period during which the rice cooking heater 4 is energized is counted in the step.

Then, in the step, it is determined whether or not t ₁ sec. has elapsed, and if it has not elapsed, the rice cooking heater 4
Continue to energize. After t ₁ sec., it is determined in step whether the detected temperature is below t ₁ ℃, and if it is below, electricity continues to be applied to the rice cooking heater 4, but if it is above, rice cooking is stopped in step. The power supply to the heater 4 is cut off, and at the same time, the counting of the power supply time is stopped in step. In either case, it is determined in step whether t ₂ sec. has elapsed or not, and if it has not elapsed, the previous operation is continued as is. t ₂
sec., it is determined in step whether the detected temperature is below T ₂ °C, and if it is below, the rice cooking heater 4 is energized and the energization time is counted, and if it is above In step, the power supply to the rice cooking heater 4 is cut off and the count of the power supply time is stopped.

and in each case t ₃ in step
Determine whether or not sec. has elapsed, continue the previous operation until it has elapsed, then determine whether the temperature T ₃ °C corresponding to the above time t ₃ sec. has not been reached and start cooking rice. The heater 4 is energized and the energization time is counted, or the rice cooking heater 4 is energized and the energization time is stopped counting.

Thereafter, by sequentially reading out the time data to sec. and temperature data _{T o ℃} stored in the microcomputer 10 in correspondence with the preset rice cooking temperature curve, and performing the same determination process as above,
When viewed partially, the rice is slightly deviated from the rice cooking temperature curve, but when viewed as a whole, the rice cooking process can be performed in accordance with the rice cooking temperature curve.

After performing the judgment processing on all the time data and temperature data, the steps are as follows.
If the count of energization time is c ₁ to c ₂ or c ₂ to _{c 3}
, c ₃ to c ₄ , or c ₄ or more.

After that, the rice cooking power is set in any one of steps 〓〓, 〓〓, 〓〓 in correspondence with the above-mentioned count number, and from then on, rice is cooked with the set rice cooking power.

In the above case, if c ₁ < c ₂ < c ₃ < c ₄ , the amount of rice cooked is the smallest when the count is c ₁ to _{c 2} , and the amount of rice cooked is the second when the count is c ₂ to c ₃ . less, c ₃
The amount of rice cooked is the third smallest in the case of ~ c ₄ , and the amount of rice cooked is the largest in the case of c ₄ or more.

Therefore, even as rice cooking power, the count is c ₁
If the count is between c ₂ and c 3, then P ₁ w; when the count is between c ₂ and _{c 3} , it is P ₂ w; when the count is between c ₃ and c ₄ , it is P ₃
w, and if the count is c ₄ or more, then P ₄ w.

Thereafter, by applying the above-mentioned set rice cooking power to the inner pot 2, the boiling state is maintained, and in step 〓〓, it is checked whether the rice cooking is finished or not, that is, the center thermometer 5 determines whether there is any moisture in the inner pot 2. The temperature gets warmer
Determine whether or not the temperature has risen rapidly to 100℃ or higher, and if the rice has not finished cooking, continue the boiling state as described above,
If the rice cooking has been completed, the power supply to the rice cooking heater 4 is stopped in step 〓〓, and thereafter, the shading process is performed.

With the above configuration, energization and interruption of energization to the rice cooking heater 4 can be controlled so as to approximately follow the preset rice cooking temperature curve, and the total energization time to the rice cooking heater 4 within the range of about 40°C to 100°C can be controlled. The amount of rice cooked can be detected based on the amount of this count, and the subsequent rice cooking power is set in accordance with this amount of rice, so delicious rice can be cooked regardless of the amount of rice cooked. I can do it.
Also, if you use an 8-bit microcomputer with built-in A/D conversion, you can set up to 256 temperatures from b ₁ to b _o , which allows you to set the actual temperature during rice cooking amount detection and the above set temperature. The discrepancy will almost disappear.

In addition, in the above, the temperature range for determining the amount of cooked rice is changed, the total energization time is counted instead of counting the total energization time to the rice cooking heater 4, and the ratio of the total energization time to the total energization and interruption time is changed. It is possible to calculate, etc.

As described above, the energization to the rice cooking heater is controlled by comparing the preset rice cooking temperature curve and the temperature of the inner pot within a preset range, and the energization time or energization cutoff time to the rice cooking heater is controlled. If the amount of rice to be cooked is determined by counting at least one of them, it is possible not only to keep the inner pot temperature in line with the above-mentioned rice cooking temperature curve even during the rice cooking amount determination operation period so that delicious rice is cooked, but also to make it possible to cook delicious rice. By performing the rice cooking amount detection operation in a wide temperature range from the temperature immediately after the end of the process to the boiling temperature, the rice cooking amount detection accuracy can be improved.

The suspension pin 11 may be made of a material with low thermal conductivity at least on the upper part of the inner pot lid 2a on which the radiant heat from the outer lid lower wall 9a acts. It is made of a material with low thermal conductivity, and a temperature sensor 5a for detecting the internal temperature of the inner pot 2 is provided at the tip thereof.
Various design changes can be made without departing from the gist of the invention, such as by surrounding the suspension pin 11 with a cover made of a material with high thermal conductivity and constructed separately from the suspension pin 11.

<Effects> As described above, in order to detect the internal temperature of the inner pot, the present invention allows the lower end of the suspension pin to face the inner pot, and thermally connects the lower end with the atmosphere inside the inner pot to detect the temperature. Since the sensor is attached, the internal temperature of the inner pot can be directly detected with the temperature sensor, and very accurate temperature detection is possible.

Therefore, especially in a rice cooker that incorporates a microcomputer to determine the amount of rice to be cooked and to control the rice cooking power, it has the unique effect of being able to cook very delicious rice.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway side view of the rice cooker, Figure 2 is an enlarged sectional view showing the temperature sensor for detecting the temperature inside the inner pot, Figure 3 is the rice cooking temperature curve, and Figure 4 is the main part of the rice cooker. FIG. 5, which is a diagram showing the electrical configuration, is a flowchart showing a program for determining the amount of rice to be cooked. 1...Rice cooking jar, 2...Inner pot, 2a...Inner pot lid, 5a...Temperature sensor for detecting the internal temperature of the inner pot,
11... Hanging pin, 11a... Cylindrical part of the hanging pin, 11b... Stopper part.

Claims (1)

[Claims] 1. A rice cooker with a temperature sensor is provided with a hanging pin projecting downward from the bottom surface of the outer lid, and the lower end of this hanging pin is fitted to the inner pot lid to detachably suspend the inner pot lid. A rice cooker with a temperature sensor, characterized in that a lower end of the hanging pin faces into the inner pot, and a temperature sensor is attached to the lower end by being thermally connected to the atmosphere inside the inner pot.