JPH0477565B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a rice cooker, and more specifically, it cooks rice by applying heat from the bottom to an inner pot containing water and rice. The present invention relates to a rice cooker that controls the amount of heating by detecting the temperature of the inner pot.

<Prior Art> Rice cookers incorporating microcomputers have conventionally been provided in order to cook delicious rice by supplying an amount of heat to an inner pot according to the amount of rice to be cooked.

As such a rice cooker, the applicant of this patent installs a sensor that detects the temperature on the bottom of the inner pot, heats it with a rice cooker heater, and when the inner pot temperature rises to the first predetermined temperature t1. The heating is interrupted at , and the temperature of the inner pot reaches the second predetermined temperature t2 (t2<
By measuring the time taken to descend to t1), the amount of rice and water in the inner pot (hereinafter referred to as the amount of cooked rice) is detected, and from then on, the rice heater is turned on to give the inner pot an amount of heat corresponding to the amount of cooked rice. The company has applied for a patent on a method for determining the amount of cooked rice that controls the amount of electricity applied to the rice.

Furthermore, after rice cooking is completed, the temperature of the upper part of the inner pot is detected by one heat-sensitive element to control the amount of electricity supplied to the heat-retaining heater to maintain the rice at the optimum temperature.

<Problems to be solved by the invention> With the method for determining the amount of cooked rice described above, the time required for the inner pot temperature to drop by a predetermined temperature (t1-t2) increases or decreases in accordance with the amount of cooked rice. By accurately detecting the above-mentioned time using a microcomputer, it is possible to accurately determine the amount of cooked rice. However, since it is necessary to interrupt heating in the middle of the rice cooking process, the time required for cooking the rice becomes longer. There is an inconvenience that this will occur.

Regarding the heat-keeping operation, the temperature at which the rice is kept warm can be controlled fairly accurately by using a microcomputer, but the temperature at which the rice is kept warm is significantly affected by the outside temperature. In other words, in the summer when the outside temperature is high, the insulating temperature tends to be kept low, which tends to cause the rice to rot, and in the winter, when the outside temperature is low, the insulating temperature tends to be kept high, causing the rice to dry out. This has the disadvantage that it ends up being too much. To explain in more detail, when the temperature setting of the heat-sensitive element is set based on the outside temperature of 20°C, if the actual outside temperature is 35°C, the heat retention temperature will be approximately 69°C or lower.
If the outside temperature is -5°C, the insulation temperature will be approximately 76°C or higher.

<Object of the invention> This invention was made in view of the above problems, and it is possible to determine the amount of cooked rice without loss time, and
The purpose of the present invention is to provide a rice cooker capable of maintaining heat unaffected by outside temperature.

<Means for Solving the Problems> In order to achieve the above object, the rice cooking jar of the present invention has a rice cooking heater attached to the bottom of an inner pot storage container that accommodates an inner pot. A sensor casing is attached that contacts the center of the bottom surface of the inner pot, a first heat-sensitive element is attached at a position close to the top surface of the sensor casing, and a second heat-sensitive element is attached at a position separated from the top surface. The rice-cooking heater and the heat-retaining heater are controlled based on the difference in temperature detected by the first and second heat-sensitive elements.

<Function> With the rice cooker having the above configuration, during rice cooking, the heat-sensitive element located close to the top surface of the sensor casing is almost unaffected by the outside temperature and follows the rise in temperature of the inner pot with almost no time delay. The heat-sensitive element, located quite far from the top of the sensor casing, is affected by the outside temperature and heat is transferred with a considerable delay, so it detects a temperature rise quite late from the temperature rise of the inner pot. (See Figure 3). This time delay becomes shorter when the amount of rice cooked is small, and becomes longer when the amount of rice cooked is large, so that the amount of rice cooked can be determined without interrupting the rice cooking operation.

Furthermore, during heat retention, both the heat-sensitive element located close to the top surface of the sensor casing and the heat-sensitive element located quite apart from the top surface of the sensor casing are affected by the inner pot temperature and the outside air temperature. Since the influence of outside temperature is quite different between the former and the latter, it is possible to determine whether the outside temperature is high or low based on the difference in the detected temperature between the two, and regardless of the outside temperature, there is no risk of spoilage or overdrying. Temperature can be controlled.

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

FIG. 5 is a longitudinal sectional view showing the rice cooker, in which a lid unit 7 is attached to the upper part of the casing 1 so as to be openable and closable. More specifically, the casing 1 has a cylindrical side member 2 whose upper portion is made of a thin metal plate, and a bottom member 3 whose lower portion is made of synthetic resin. An inner pot storage container 5 is attached to the inner side of the casing 1, and an inner pot 6 is placed on a rice cooking heater 54 inside the inner pot storage container 5 and is housed in a removable manner.

More specifically, the casing 1 has a bottom member 3 made of synthetic resin attached to the lower end of a side member 2 having a cylindrical shape made of metal, and an upper member 11 made of synthetic resin attached to the upper end. There is.

The bottom member 3 is formed into a deep dish shape that can cover substantially the lower half of the inner pot storage container 5. Then, a predetermined position near the periphery of the bottom surface is recessed upward to form a power supply component housing recess 33 that accommodates a power supply component 34 such as a transformer, and a predetermined position on the upper rising portion is recessed into the inner package. This forms a control board accommodating recess 35 for accommodating a control board 36 on which a microcomputer chip or the like is mounted. A cover 37 is attached to the power supply component accommodation recess 33 with screws to prevent the power supply component 34 in the housed state from being exposed to the outside, and a cover 37 is attached to the control board accommodation recess 35 in the housed state. A cover 38 prevents the control board 36 from being exposed to the outside and also serves as an operation panel.
is attached with screws. Note that 39 is an opening for inserting a power cord formed at a predetermined position in the power supply component housing recess 33, and 30 is a cord reel.

The side member 2 is a thin metal plate formed into a cylindrical shape, and the lower end edge and the upper end edge are curved inward so as to have a substantially cylindrical shape to form a ring portion 2.
1 and 22 are formed, and are engaged with the annular groove 23 of the bottom member 3 and the annular groove 24 of the upper member 11 in a watertight manner, and the engaged state can be ensured by screws 25.

The upper member 11 is made of synthetic resin and has a generally ring-like shape as a whole, and has a support part 12 on the upper surface that supports the upper end flange part 51 of the inner pot storage container 5 in a suspended manner. , upper end flange 61 of the inner pot 6
A support part 13 that supports the holder in a hanging manner is formed concentrically with the support part 13 . A shoulder portion 14 that supports the lid unit 7 in a vertically movable manner is formed at a predetermined position, and an engaging portion that holds the lid unit 7 in a closed state is located at a position directly facing the shoulder portion 14. It has 15.

The inner pot storage container 5 is formed in a shape capable of accommodating the inner pot 6, and has a sensor casing 53 attached thereto by penetrating the center portion of the bottom surface, and a rice cooking container that surrounds the sensor casing 53. A heater 54 is installed. The upper end edge portion is curved outward to form an upper end flange portion 51 that can be engaged with the support portion 12 . In addition, 55 is a heat shield plate, and a support plate 5 for insulation resistance testing is installed at a predetermined position.
6 is attached and brought into contact with the casing of the cord reel 30. 58 is a heat-retaining heater attached to a predetermined position on the side of the inner pot storage container 5;
is a temperature fuse, and 50 is a heat insulating material that surrounds almost the entire side surface of the inner pot storage container 5.

The lid unit 7 has a handle 71 on the top and a heat sink 72 on the bottom.
Then, the lid heater 7 is placed at a predetermined position on the upper surface of the heat sink 72.
4 is attached, and a steam packing 73 is attached to the outer periphery of the heat sink plate 72 so that it can come into contact with the flange portion 61 of the inner pot 6. Further, a one-touch pin 75 is attached to the center of the heat dissipation plate 72, and a one-touch packing 77 attached to the center of the lid plate 76 that contacts the stepped portion 62 of the inner pot 6 is detachably attached to the one-touch pin 75. ing. Note that 78 is an operating lever for opening and closing the lid unit 7, 79 is a lead wire for applying voltage to the lid heater 74, and 70 is a hinge cover that is force-fitted into a predetermined position of the side member 2. be.

FIG. 1 is a diagram schematically showing the sensor casing 53, and shows an upper surface plate 53a that contacts the bottom surface of the inner pot 6.
An insulating sheet 53b is attached to the lower surface of the
Furthermore, a first heat-sensitive element 81 is attached in contact with the center of the lower surface of the insulating sheet 53b.
A second heat sensitive element 82 is attached at a predetermined position separated from the first heat sensitive element 81 by a predetermined distance. Then, as described below, the rice cooking heater and the heat-retaining heater are controlled based on the difference in temperature detected by the first heat-sensitive element 81 and the second heat-sensitive element 82.

FIG. 2 is a block diagram showing the electrical configuration of the main parts of the rice cooker, in which the temperature detection signal from the first heat sensitive element 81 and the temperature detection signal from the second heat sensitive element It is supplied to the microcomputer 83 via a D converter or the like, and the control signal from the microcomputer 83 is supplied to the rice cooking heater 54 and the warming heater 58 via a drive circuit (not shown).

FIG. 4 is a flowchart illustrating the operation of performing the rice cooking operation using the rice cooking power according to the amount of rice to be cooked.
Wait until the temperature detected by the heat-sensitive element 81 reaches 70°C, and start the timing operation in step,
In the step, the above-mentioned full power energization is continued, and in the step, the second heat-sensitive element 82 is
Wait until the detected temperature reaches 70℃, then
In step , , it is determined whether the measured time is less than 10 seconds, 10 to 20 seconds, 20 to 30 seconds, or 30 seconds or more. If it is less than 10 seconds, the rice cooking heater 54 is energized with 9/14 power in step, and if it is 10 to 20 seconds, the rice cooking heater 54 is energized with 12/14 power in step.
If it is 20 to 30 seconds, the rice cooking heater 54 is energized at full power in step, and if it is 30 seconds or more, an abnormality is displayed in step.
Then, after performing the processing in the above steps, the first thermal element 81 is
Determine whether the detected temperature has reached 130℃,
If the temperature has not reached 130℃, repeat the above steps.
, the following determination and processing are repeated, and when the temperature reaches 130°C, the rice cooking operation is finished and a steaming operation (not shown) is performed.

That is, by performing the rice cooking operation, the temperatures detected by the first heat sensitive element 81 and the second heat sensitive element 82 increase, and the changes in the detected temperatures of both are as shown in FIG. , a time difference occurs. This difference is due to the difference in the mounting position of both heat-sensitive elements 81 and 82, and after the temperature detected by the first heat-sensitive element 81 shown by the solid line in the figure reaches 70°C, the second heat-sensitive element 81 shown by the broken line The time △t until the temperature detected by the element 82 reaches 70°C becomes longer when the amount of rice cooked is large because the temperature rises slowly; on the other hand, when the amount of rice cooked is small, the temperature rises suddenly. becomes shorter. Therefore, the amount of rice to be cooked can be detected based on the length of the above-mentioned time Δt, and the power application for performing the rice cooking operation is not interrupted midway, so the time required for rice cooking can be shortened. I can do it.

FIG. 6 is a flowchart for explaining the heat-retaining operation, and in steps . 8
Determine whether the temperature detected by step 2 is below 70°C or below 71°C. Then, the first thermal element 8
If the temperature detected by the first heat-sensitive element 81 is higher than 70 degrees Celsius, and the temperature detected by the first heat-sensitive element 81 is higher than 71 degrees Celsius, the temperature insulated heater 58 is energized with a power of 9/14 in the step. In the step, the heat insulating heater 58 is energized with a power of 5/14. Furthermore, the temperature detected by the first heat-sensitive element 81 is
If the temperature detected by the second heat-sensitive element 82 is higher than 71°C and the temperature detected by the second heat-sensitive element 82 is 70°C or lower, the power to the heat-retaining heater 58 is cut off in step, and the temperature detected by the second heat-sensitive element 81 is higher than 70°C. Moreover,
If the temperature is below 71°C, the heat retaining heater 58 is energized with 5/14 power in step, and if the temperature detected by the second heat sensitive element 82 is higher than 71°C, the power to the warm heater 58 is cut off in step.

After performing any of the processes from step to step, the step-to-step determination operation is performed again.

That is, since the amount of electricity supplied to the heat-retaining heater 58 is controlled based on the temperature detected by the second heat-sensitive element 82, which is susceptible to the influence of the outside temperature, the heat-retaining temperature (70 to 74°C) is maintained regardless of changes in the outside temperature. temperature (including mass production errors) can be maintained. In the case of the conventional example in which the heat retention temperature is controlled using only the first heat-sensitive element 81, this is 69 times without including mass production errors.
This means that the temperature control system has been significantly improved compared to when the temperature was ~75℃.

7 and 8 show the sensor casing 53
The mounting structure is shown in Fig. 7.
An outward facing flange is formed at the upper end of the outer case of the sensor casing 53, and a predetermined position is an outwardly drawn and raised part, and the inner edge of the rice cooking heater section is held between the flange and the drawn and raised part. There is. In addition, in FIG. 8, the shielding plate that shields between the inner pot detection reed switch and the magnet is extended,
This extension part is fixed to the rice cooking heater part by screws or the like.

FIG. 9 is a front view of the operation panel 4, which includes a timer display 41, a timer set button 42, a cancel/warm switch 43, a quick-cook rice switch 44, and a rice-cook switch 45.

FIG. 10 is a flowchart illustrating the operation when the cancel/keep warm switch 43 is operated. When a setting operation state such as rice cooking is selected, it is determined in step whether the cancel/keep warm switch 43 is ON or not. However, if it is ON, in the step
Wait until 0.5 seconds have elapsed, and in step it is determined again whether the cancel/keep warm switch 43 is ON or not. If it is ON, the set operating state is canceled in step, but if it is determined in step that it is OFF, The selected setting operation state, such as rice cooking, is continued in step.

Therefore, it is possible to reliably prevent the inconvenience of inadvertently canceling the set operating state, such as when the cancel/warm switch 43 is touched by mistake.

FIG. 11 is a flowchart illustrating the timer setting operation, in which the process waits until the timer switch is turned on in step, and then determines whether one second has elapsed in step.

If the step determines that one second has not elapsed, the step determines whether the upper limit time (for example, 15:00) has been reached, and if it is the upper limit time, the display is cleared in the step.
If it is not the upper limit time, display at the step.
Move forward by 10 minutes, wait until 0.5 seconds have elapsed in the step, and perform the determination and processing below the step again.

Also, if it is determined in the above step that 1 second has elapsed, the step determines whether or not the upper limit time has been reached, and if it is the upper limit time, the display is cleared in the step, but it must be the upper limit time. For example, at the step, advance the display by 1 hour, at the step, wait until 0.1 seconds have elapsed, and at the step, set the timer switch again.
It is determined whether it is ON or not, and if it is ON, the determination and processing from the above steps are performed, but if it is OFF, the timer setting operation is ended.

Therefore, turn on the timer switch for a short time.
By turning on the timer switch, the time can be increased by 10 minutes, and by turning on the timer switch for a long time, the time can be increased by 1 hour.

<Effects of the Invention> As described above, in the present invention, the first heat-sensitive element is attached to a position close to the upper surface of the sensor casing, and the second heat-sensitive element is attached to a position separated from the upper surface of the sensor casing. Since this is installed, the amount of rice to be cooked, that is, the total number, can be determined based on the time delay in the rise in the temperature detected by the second heat-sensitive element with respect to the rise in the temperature detected by the first heat-sensitive element.

Alternatively, it provides a unique effect that can be effectively utilized, such as being able to perform good heat retention control that is not affected by outside air temperature, based on the difference between the detected temperatures of the first heat-sensitive element and the second heat-sensitive element.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the sensor casing, Figure 2 is a block diagram showing the electrical configuration of the main parts of the rice cooker, Figure 3 is a diagram showing changes in temperature detected by both heat-sensitive elements, and Figure 4 is the amount of rice cooked. Flowchart explaining the operation of cooking rice with rice cooking power according to the rice cooking power, FIG. 5 is a longitudinal cross-sectional view showing the rice cooking jar, FIG. 6 is a flowchart explaining the warming operation,
8 is a diagram showing the mounting structure of the sensor casing, FIG. 9 is a front view of the operation panel, FIG. 10 is a flowchart explaining the operation when the cancel/warm switch is operated, and FIG. 11 is the timer set operation. Flowchart explaining. 5... Inner pot storage container, 6... Inner pot, 53... Sensor casing, 54... Rice cooking heater, 81...
First heat sensitive element, 82... second heat sensitive element.

Claims (1)

[Claims] 1. In a rice cooker in which a rice cooking heater is attached to the bottom of an inner pot storage container that accommodates an inner pot, a sensor casing is attached that contacts the center of the bottom surface of the inner pot in the stored state, and a sensor casing that is close to the top surface inside the sensor casing is installed. A first heat-sensitive element is attached at a position, and a second heat-sensitive element is attached at a position away from the top surface.
A heat-sensitive element is attached to the first and second heat-sensitive elements.
A rice cooker characterized in that a rice cooker and a heat-retaining heater are controlled based on a difference in temperature detection by a heat-sensitive element.