JPH021488B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a rice cooker in which a pot is heated by a rice cooking heater to perform a rice cooking operation.

(Prior art) In conventional rice cookers, a switch device that combines magnetic shunt steel as a temperature detection element, a permanent magnet, an operating lever, a micro switch, etc. is widely used to control the end time of rice cooking. Such a switch device is generally constructed as follows.

That is, a heat-sensitive cap is provided that presses against the outer bottom of the cooking pot when the cooking pot is installed in a predetermined position, and magnetic shunt steel, which loses its magnetism at a certain Curie point temperature, is transferred inside this heat-sensitive cap. The temperature of the rice to be cooked is detected as the temperature of the pot using the magnetic shunt steel. At this time, the Curie point temperature of the magnetic steel is selected to be approximately equal to the temperature at which rice is cooked (generally around 130° C.). In addition, a permanent magnet is attached to the tip of an operating lever that is rotatable between two positions, and this operating lever is capable of attracting the permanent magnet to magnetic shunt steel in response to an external operation. While being rotated to the first position, it is rotated back to the second position in response to the permanent magnet being released from attraction as the magnetic shunt steel loses its magnetism. The micro switch is turned on when the control lever is rotated to the first position and turned off when the control lever is rotated to the second position, and in the on state, the rice cooking heater is turned on. The configuration is such that an electric path is formed.

Therefore, in a rice cooker equipped with a switch device configured as described above, when the operation lever is rotated to the first position, the rotation state is changed due to the attraction between the permanent magnet and the magnetic shunt steel. At the same time, the micro switch is turned on, and in response, the rice cooking operation by the rice cooking heater is started. After this, as the rice cooking continues, the inside of the pot exhibits a so-called dry-up state, and when the temperature (detected temperature) of the magnetic steel becomes higher than the rice cooking temperature and its magnetism disappears, the permanent magnet's attraction is released. Accordingly, the operating lever is rotated back to the second position and the micro switch is turned off, so that the rice cooking heater is cut off and the rice cooking operation is ended.

Additionally, rice cookers with a so-called double-cooking function have become popular, allowing the pot to be reheated for a short period of time after the rice has finished cooking, thereby removing excess water from the rice and making it more delicious. In such rice cookers, for example, a double-cooking timer is provided that starts operating when the micro switch is turned off, and the double-cooking operation is controlled by the output of this timer. It is composed of

(Problem to be solved by the invention) Thermal conductivity between the outer bottom of the pot and the heat-sensitive cap,
Also, the thermal conductivity between the heat-sensitive tube and the magnetic shunt steel is
Since these parts vary to some extent due to processing accuracy, assembly accuracy, etc., it is inevitable that an error will occur between the actual temperature of the pot and the temperature detected by the magnetic shunt steel. On the other hand, since the Curie point temperature of magnetic shunt steel is constant, the temperature of the pot when the magnetic shunt steel loses its magnetism, that is, the temperature of the pot when the rice cooking operation is terminated by the switch device, is
It will vary depending on the rice cooker. As a result, in the conventional rice cooker, there is a possibility that the control of the end timing of the rice cooking operation may become inaccurate.

One possible way to deal with these problems is to provide an adjustment mechanism to adjust the thermal conductivity of the magnetic shunt steel, but it is actually extremely difficult to provide such an adjustment mechanism. be. For this reason, conventionally, a predetermined tolerance temperature range is set for the operating temperature of the switch device (the temperature at which magnetic shunt steel loses its magnetism), and when manufacturing rice cookers,
Quality control is carried out so that the operating temperature of the switch device falls within the above-mentioned allowable error temperature range. In other words, in the conventional rice cooker, the actual situation is that the control of the end time of the rice cooking operation is relatively loose, and this point has been an unresolved problem.

Furthermore, in the near future, it is expected that rice cookers configured to always perform the above-mentioned double heating during normal rice cooking operations will become mainstream. However,
When actually using a rice cooker, in addition to the normal cooking as described above, it is also used to cook rice for takikomi rice. The following problems arise. In other words, when cooking rice for takikomi rice, seasonings such as soy sauce are added to the pot and tend to burn when the rice is cooked, so it is not recommended to heat the rice by cooking it twice. It is. For this reason, if the configuration is such that double-cooking and heating are always performed as described above, there will be a problem in that the cooked rice will become extremely burnt when cooking for rice that has been left over. In addition, as a means to suppress the amount of burnt rice that is cooked, it is possible to lower the operating temperature of the switch device (the temperature at which the rice cooking operation ends), but as mentioned earlier, with conventional rice cookers, the switch device Since the operating temperature of the device is a constant temperature that depends on the Curie point temperature of the magnetic shunt steel, it is impossible to suppress the amount of scorching by the above-mentioned means.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to accurately control the end timing of the rice cooking operation, to make the rice delicious by double-cooking and heating, and to make it possible to cook the rice deliciously. To provide a rice cooker which has effects such as being able to cook rice while suppressing the amount of burnt rice.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a rice cooking heater for heating a pot and a temperature detection means for detecting the temperature of the rice to be cooked and outputting a temperature information signal according to the detected temperature. , when the temperature indicated by the temperature information signal reaches a predetermined temperature during the rice cooking operation by the rice cooking heater, the rice cooking heater is switched to a power-off state, and when a predetermined condition is satisfied thereafter, the rice cooking heater is reenergized; Similarly, when the temperature indicated by the temperature information signal reaches a predetermined temperature during the rice cooking operation using the rice cooking heater, the rice cooking heater is switched to a power-off state, and the power is then turned off. A control means is provided having a storage section that stores heating patterns for cooked rice that maintain a state, and the control means is configured to control the rice operation according to the heating pattern for twice-cooking and the rice cooking operation according to the heating pattern for cooked rice. The configuration is such that it can be executed selectively.

(Function) The temperature information signal used to control the end timing of the rice cooking operation changes depending on the temperature of the rice to be cooked detected by the temperature detection means and is not fixed. Even if the thermal conductivity between the object and the temperature detection means varies, the temperature detected by the temperature detection means can be easily compensated for. Therefore, it becomes possible to accurately control the end timing of the rice cooking operation. The control means also controls the rice cooking operation according to the double-cooking heating pattern of switching the rice cooking heater to a power-off state based on the temperature information signal and then re-energizing the rice cooking heater when a predetermined condition is satisfied; The configuration is such that after the rice heater is cut off based on the information signal, the rice cooking operation is selectively performed using the cooking rice heating pattern without re-energizing as described above. Not only can the rice be cooked deliciously, but there is no risk that the amount of cooked rice will increase when cooking rice.
In particular, when cooking rice for seasoning, it is possible to easily compensate for the temperature detected by the temperature detection means as described above, so it is also possible to reduce the amount of scorched rice by cutting off the power to the rice heater earlier. It becomes possible.

(Example) First, in FIG. 3, 1 is a substantially circular outer case, 2 is a bottom frame fitted to the lower part of the outer case 1, and 3
4 is a heat insulating material interposed between the outer case 1 and the inner case 3; and 5 is a pot detachably attached to the inner case 3.
Further, 6 is a rice cooking heater disposed at the inner bottom of the inner case 3, 7 is a heat-retaining heater wrapped around the upper outer periphery of the inner case 3, 8 is a lid rotatably supported on the outer case 1, and 9 is a rocket mechanism that holds the lid 8 in a locked state. Reference numeral 10 denotes a heat transfer cap which is provided so as to be pressed against the outer bottom of the pot 5 by the force of a spring (not shown), and a thermistor 11, such as a thermistor 11, serving as a temperature detection means is disposed inside the cap in a thermally conductive manner. ing. Therefore, this thermistor 11
is the temperature of the food to be cooked in the pot 5 that corresponds to this.
(hereinafter referred to as pot bottom temperature D), and a change in resistance value corresponding to the detected temperature is output as a temperature information signal Sd.

In addition, in Fig. 4, 12 is a clock device disposed on the outside of the outer case, which indicates the hours and minutes.
It consists of a display section 13 that digitally displays the information, and an operation section 14. The clock device 12 has a normal clock function and a timer function for a well-known timer switch, and the selection and adjustment of each function is performed by each operation button 14a of the operation section 14. Furthermore, 15 is a heating pattern selection device which is an operation means also disposed on the outside of the outer case 1, and this has, for example, three operation buttons 15a, and these operation buttons 15a are used for cooking porridge, which will be described later. Any one can be selected from among the heating pattern, the heating pattern for twice-cooked rice, and the heating pattern for cooked rice. At this time,
The heating pattern selection device 15 outputs a pattern selection signal Sp that can specify the selected heating pattern. Note that 16 is a display device disposed on the outside of the outer case 1, which includes, for example, four display lamps 16.
a, and each light indicates the current operating state. At this time, the display device 16 is adapted to display the operating states of "rice cooking", "double cooking", "uniform cooking", and "keep warm".

Next, the electrical configuration will be explained with reference to FIGS. 1 and 2. First, in FIG. 2 showing the outline of the electric circuit configuration, 17 is a bidirectional three-terminal thyristor (hereinafter simply referred to as thyristor), and a series circuit between this and the rice cooking heater 6 receives power from the plug 17a. It is connected. Further, the warming heater 7 is connected in parallel with the thyristor 17, so when the thyristor 17 is turned off, the rice cooking heater 6 and the warming heater 7 are energized in series, and the rice cooking heater 6 is in a substantially power-off state. Then, the pot 5 is heated over low heat. Furthermore, when the thyristor 17 is turned on, the rice cooking heater 6
Only the pot is energized, which generates heat with a relatively large output, and the pot 5 is heated with high heat. Reference numeral 18 denotes a voltage adjustment device that constitutes the power supply control means 19 together with the thyristor 17, which is interposed in the current conduction path of the rice cooking heater 6, and controls the output amount by suppressing the voltage between the terminals of the rice cooking heater 6. This is a configuration that allows adjustment. Note that the output amount of the rice cooking heater 6 does not necessarily need to be adjusted by the voltage regulator 18 as described above, and can also be adjusted by, for example, phase control of the thyristor 17 or on/off duty ratio control.

Thus, the voltage regulator 18, together with the thyristor 17 and the clock device 12, is controlled by a control circuit device 20 serving as a control means. As shown in FIG. 1, this control circuit device 20 is configured as a microcopy unit including a storage section 21, a time control section 22, and an arithmetic processing section 23, and the storage section 21 includes a thyristor 17. and three types of programs (described later) for controlling the voltage regulator device 18 in a predetermined manner are stored corresponding to the three types of heating putters. Further, the time control section 22 is connected to an oscillator 24.
It is provided to receive the clock pulse Pc from the arithmetic processing section 23, and outputs a time information signal St for timing based on a command from the arithmetic processing section 23. The arithmetic processing section 23 is provided to receive the temperature information signal Sd from the thermistor 11, the pattern selection signal Sp from the heating pattern selection device 15, and the time information signal St from the time control section 23 as data inputs. The pattern selection signal Sp
A program corresponding to the program is read from the storage unit 21, and the thyristor 17 and the voltage regulator 18 are controlled based on the read program, the temperature information signal Sd, and the time information signal St, thereby creating a heating pattern corresponding to the program. This is the configuration you get. Further, the arithmetic processing section 23 is adapted to also control the clock device 12.

Now, below, the specific operation that the arithmetic processing section 23 executes based on the program read from the storage section 21 will be explained with reference to FIGS. 5 to 7 as well as the effects of each heating pattern. In addition, FIG. 5A, FIG. 6, and FIG. 7 show temperature characteristic curves whose horizontal and vertical axes correspond to time T and pot bottom temperature D (℃), respectively, and FIG. The vertical axis shows the time T and the output P (W) of the rice cooking heater 6, respectively.
The temperature characteristic curve corresponding to

()... Heating pattern for cooking porridge (see Fig. 5) When a heating pattern for cooking porridge is selected by the heating pattern selection device 15 and a pattern selection signal Sp that can identify the heating pattern is output, The arithmetic processing unit 23 turns on the thyristor 17 to energize only the rice cooking heater 6 based on the program from the storage unit 21 . Therefore, when the pot 5 is heated over high heat, the bottom temperature D of the pot rises relatively rapidly, and the thermistor 1 detects this.
1 outputs its own resistance value change as a temperature information signal Sd. Then, at time t ₁ , the pot bottom temperature D=
When the temperature information signal Sd corresponding to 80° C. is output, the arithmetic processing unit 23 operates the voltage regulator 18 in accordance with this to adjust the amount of heat generated by the rice cooking heater 6.
Heat the pot 5 over low heat, controlling the temperature to about 100 watts. As a result, the pot bottom temperature D is raised relatively slowly. Then, when the pot bottom temperature D reaches 98°C (time t ₂ ), the arithmetic processing unit 23 sends the time information signal St to the time control unit 22 after 20 minutes.
Issue a command to output. after this time t ₂
At time t ₃ after 20 minutes, the above-mentioned time information signal St
is output, the arithmetic processing unit 23 that receives it
At the same time as the operation of the voltage regulator 18 is canceled, the thyristor 17 is turned off to energize the rice cooking heater 6 and the heat-retaining heater 7 in series, thereby shifting to an uneven operation in which the pot 5 is further heated over low heat. Due to the above-described actions, the rice stored in the pot 5 together with an appropriate amount of water can be cooked into porridge. In particular, during such "cooking porridge", the pot 5 is heated over a low heat of about 100 watts from time t ₂ when the pot bottom temperature D reaches 98°C to time t ₃ . This prevents the soup from boiling over due to excessive boiling.

()... Heating pattern for double-cooking (see Figure 6) The heating pattern for "double-cooking" is selected by the heating pattern selection device 16, and this serves as a rice-cooking start command signal that allows the heating pattern to be specified. When the pattern selection signal Sp is output, the arithmetic processing unit 23 turns on the thyristor 17 to start the rice cooking operation based on the program from the storage unit 21, and heats the pot 5 with high heat using the rice cooking heater 6. Bring the water in the pot 5 to a boil. During this boiling period, the bottom temperature D of the pot is maintained at approximately 100℃,
When the water in the pot 5 evaporates and is absorbed by the rice, resulting in a so-called dry-up state, the bottom temperature D of the pot rises rapidly. As a result, when the thermistor 11 outputs the temperature information signal Sd corresponding to the pot bottom temperature D=130°C (time t ₄ ), the arithmetic processing unit 23 turns off the thyristor 17 in response to this and shifts to uneven operation. At the same time, a command is issued to the time control section 22 to output the time information signal St after 5 minutes have elapsed. this time t ₄
When the above-mentioned time information signal St is output at time _t5 , which is 5 minutes later, the arithmetic processing unit 23 that receives this turns on the thyristor 17 for only 1 minute, thereby turning on the pot 5 during this on period. The rice is reheated over high heat to perform so-called twice-cooking, and then the above-mentioned shading operation is performed. In other words, when a predetermined condition is established that 5 minutes have passed after the end of the rice cooking operation, the double cooking operation is controlled as described above, and as a result, the excess moisture in the cooked rice is removed. The food becomes delicious when it is blown away.

()...Heating pattern for cooked rice (see Figure 7) This heating pattern takes care of the situation where when making cooked rice, seasonings such as soy sauce are put into the pot 5, which tends to cause sticking. This is what I did. That is, the heating pattern selection device 15
When the heating pattern for cooked rice is selected and the heating pattern selection signal Sp is outputted, the calculation processing section 23 turns on the thyristor 17 based on the program from the storage section 21 in accordance with each heating described above. Similar to pattern. After that, when the pot 5 exhibits a dry-up state and the bottom temperature D of the pot rises rapidly, the thermistor 11 outputs a temperature information signal Sd corresponding to the pot temperature D=110°C at time _t6 , and the arithmetic processing unit 23
In response to this, the thyristor 17 is held in an off state and shifts to uneven operation. As described above, the degree of rise in the bottom temperature D of the pot is suppressed to a low level, and control is performed to prevent double cooking and heating, which makes it difficult for cooked rice to burn. A suitable heating pattern can be obtained.

In the above embodiment, when a predetermined period of time has elapsed after the transition to the uneven operation, the time control section 11
It is also possible to use a configuration in which a buzzer or the like is sounded by the button.

As described above, in this embodiment, the thermistor 11 is provided to detect the temperature of the rice to be cooked through the pot 5, and the temperature information signal Sd from the thermistor 11 is provided.
A control circuit device 20 that selectively controls a heating pattern for cooking rice porridge, a heating pattern for twice-cooking, and a heating pattern for cooking rice based on
It is characterized by the provision of . At this time, since the temperature information signal Sd is based on the resistance value, which is the easiest to handle as an electrical variable, it can be easily corrected. As a result, even if the thermal conductivities between the pot 5 and the heat-sensitive cap 10 and between the heat-sensitive cap 10 and the thermistor 11 vary during manufacturing, the temperature detected by the thermistor 11 corresponding to the above-mentioned temperature information signal is extremely high. Can be easily compensated for. Therefore, it is possible to accurately control not only the end time of the rice cooking operation but also the rice cooking operations for cooking porridge and cooked rice as described in the embodiment. Also,
Because a micro switch with a conventional mechanical contact is not required to detect the temperature of the pot 5,
There is no problem such as shortened lifespan due to contact wear. Moreover, the control circuit device 20
The rice cooking heater 6 is turned on after the rice cooking operation is finished.
A heating pattern for double-cooking that re-energizes the
Since the configuration selectively executes the heating pattern for rice cooking without re-energizing as described above after the rice cooking operation is finished, the rice can be deliciously cooked by twice-cooking heating, and the rice can be cooked deliciously. There is no need to worry about increasing the amount of scorching when producing In particular, in this embodiment, when the heating pattern for cooked rice is selected, the rice cooking operation is ended at a temperature lower than normal, so that the amount of charring can be further suppressed.

〔Effect of the invention〕

According to the present invention, as is clear from the above description, a temperature detection means for detecting the temperature of the rice to be cooked and outputting a temperature information signal according to the detected temperature is provided, and when the rice cooking operation using the rice cooking heater is performed, double-cooking heating for switching the rice-cooking heater to a power-off state when the temperature indicated by the temperature information signal reaches a predetermined temperature, and then re-energizing the rice-cooking heater when a predetermined condition is satisfied. A rice cooking operation according to a pattern, and a rice cooking operation in which the rice cooking heater is switched to a power-off state when the temperature indicated by the temperature information signal reaches a predetermined temperature during the rice-cooking operation using a rice-cooking heater, and the power-off state is maintained thereafter. Since the rice cooking operation using the rice heating pattern can be selectively executed, it is possible to accurately control the end time of the rice cooking operation and improve the reliability of the rice life. Not only can the rice be cooked deliciously, but it also has the excellent effect of suppressing the amount of burnt rice even when cooking rice for seasoned rice.

[Brief explanation of drawings]

The drawings are for explaining one embodiment of the present invention, and FIG. 1 is a block diagram of the electrical configuration, FIG. 2 is a schematic electrical circuit diagram, and FIG. 3 is a partially cutaway front view of the entire device. Figure 4 is a front view of the whole, Figure 5A is a temperature characteristic diagram to explain the effect, Figure 5B is an output characteristic diagram to explain the effect, and Figures 6 and 7 are temperature characteristics to explain the effect. It is a characteristic diagram. In the figure, 5 is a pot, 6 is a rice cooking heater, 7 is a heat retention heater, 11 is a thermistor (temperature detection means), 15 is a heating pattern selection device, 17 is a bidirectional three-terminal thyristor, 18 is a voltage regulator, and 19 is a Power supply control means, 20 is a control circuit device (control means), 2
1 is a storage section, 22 is a time control section, and 23 is an arithmetic processing section.

Claims (1)

[Claims] 1. A rice cooker heater for heating a rice cooking pot;
a temperature detecting means provided to detect the temperature of the rice to be cooked and outputting a temperature information signal according to the detected temperature; and a temperature detecting means for outputting a temperature information signal according to the detected temperature, and a temperature indicated by the temperature information signal reaches a predetermined temperature during the rice cooking operation by the rice cooking heater. a double-cooking heating pattern for switching the rice-cooking heater to a power-off state when the rice-cooking heater is turned off and then re-energizing the rice-cooking heater when a predetermined condition is satisfied; control means having a storage section that stores heating patterns for cooked rice that switch the rice cooking heater to a power-off state when the temperature indicated by reaches a predetermined temperature and thereafter maintain the power-off state; A rice cooker, characterized in that the control means is configured to be able to selectively execute the rice cooking operation using the double-cooking heating pattern and the rice cooking operation using the mixed rice heating pattern.