JPH0443150Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) This invention relates to a rice cooker that detects the temperature of a pot, and when the temperature of the pot reaches a dry-up condition, cuts off electricity to a rice cooker heater and ends the rice cooking process.

(Conventional technology) In order to properly cook rice without making the rice sticky or abnormally burnt in a rice cooker, the temperature of the pot must rise rapidly when the water in the pot runs out. It is preferable to turn off the power to the rice cooking heater and end the rice cooking process when the dry-up state is reached. In order to address such requests,
Dry-up (cooking) conditions are determined by detecting the temperature of the pot with a temperature sensor placed at the bottom of the pot.While the water is boiling, the temperature of the pot remains at a constant and stable temperature of approximately 100 degrees Celsius. The temperature is set as the reference temperature and a predetermined temperature (for example, 10℃) added to this temperature, and when the temperature sensor detects this set dry-up condition, the rice cooking heater is turned off and the rice cooking process is completed to prevent uneven rice cooking. I am trying to move on to the process.

By the way, a conventional temperature sensor for detecting the temperature of a pot is a cup-shaped heat-sensitive sensor that is provided in elastic pressure contact with the outer bottom of the pot, as disclosed in, for example, Japanese Patent Application Laid-Open No. 133213/1983. The inside of the pot is sealed with a heat-conductive mold member, and the temperature is detected on the bottom of the pot placed on the heat-sensitive section.

(Problem to be solved by the invention) When detecting the temperature of the bottom of the pot using a temperature sensor installed inside the heat-sensing part, the temperature sensor is enclosed in a molded member and installed inside the heat-sensing part. The thermal response from the pot to the temperature sensor may be poor, or the contact between the heat-sensitive surface and the pot may be poor because rice is placed on the heat-sensitive section of the pot each time rice is cooked, and the heat response from the pot to the temperature sensor may be poor. As a result, the correlation between the temperature detected by the temperature sensor and the water temperature in the pot may deteriorate due to factors such as deterioration of the temperature of the pot. changes. Therefore, for example, the amount of rice cooked,
Even if the rice cooking conditions are the same, i.e., the water temperature and water volume are the same, the dry-up conditions are different, and it is not possible to set accurate dry-up conditions that correspond to the dry-up condition in the pot. This causes the rice cooker to shut off quickly, resulting in insufficient dry-up heat and rice. There were problems such as the rice becoming sticky, or the rice cooking heater turning off too late and causing the rice to become abnormally burnt, resulting in the rice being dry and unstable.

The present invention was developed based on the above-mentioned problem, and is a rice cooker that can accurately detect the dry-up state and cook rice stably even when the correlation between the detected temperature of the pot and the water temperature in the pot deteriorates. The purpose is to provide the following.

[Structure of the invention] (Means for solving the problem) In FIG. 1, 11 is a pot temperature detection means for detecting the temperature of the pot 8, and 13 is a steam generation detection means for detecting the generation of steam in the pot 8. , 14 is a temperature obtained by adding a predetermined temperature to this reference temperature, with the pot temperature detected by the pot temperature detection means 11 at the time when a predetermined time has elapsed since the steam generation detection means 13 detected the generation of steam as a reference temperature. This is a control means that sets a dry-up condition and turns off the power to the rice cooking heater 9 when the temperature detected by the pot temperature detection means 11 reaches this dry-up condition.

(Function) The steam generation detection means 13 accurately detects the boiling point in the pot 8 by steam generation, and the relative temperature rise of the pot detected by the pot temperature detection means 11 after a predetermined period of time has elapsed from this boiling point. Since the rice cooking heater 9 is controlled based on the value, even if the correlation between the temperature detected by the pot temperature detection means 11 and the water temperature in the pot 8 is poor, the dry-up state can be accurately detected.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. In FIG. 1, reference numeral 1 denotes a rice cooker main body consisting of an inner case 2, an outer case 3, and the like. 4 is the inner lid 5
The lid is composed of an outer lid 6, an outer lid 6, etc., and is connected to the inner lid 5 and the outer lid 6, and a steam vent cylinder 7 is provided on one side. 8 is a pot detachably housed in the inner case 2, and 9 is a rice cooking heater disposed in a space between the bottoms of the inner case 2 and the pot 8. Reference numeral 10 denotes a cup-shaped heat-sensitive section provided so as to be elastically pressed against the outer bottom of the pot 8, and inside the cup-shaped heat-sensitive section, a first temperature sensor 11 serving as a pot temperature detection means is mounted by a heat-conductive mold member 12. This first temperature sensor 11 is configured to detect the temperature of the pot 8 . Reference numeral 13 denotes a second temperature sensor serving as steam generation detection means provided in the steam vent tube 7, and this second temperature sensor 13 is designed to detect the state of steam generation due to boiling of water in the pot 8. It is configured. Reference numeral 14 denotes a control means disposed at the inner bottom of the rice cooker main body 1.

In FIG. 2, the control means 14 consists of a microcomputer and controls the first and second temperature sensors 1.
A/D converter 1 that digitizes signals 1 and 13
5, an input circuit 16, a CPU 17, a clock circuit 18, a memory 19, an output circuit 20, and the like. This control means 14 controls the rice cooking heater 9 according to the rice cooking control program stored in the memory 19.
The rice is cooked by controlling energization/disconnection via the drive circuit 21. In particular, the temperature measured by the first temperature sensor 11 at the time when a predetermined time T has elapsed after the second temperature sensor 13 detects the generation of steam. is detected, and this temperature is set as the reference temperature _H1 to a predetermined temperature α (for example, 10
℃) is the dry-up condition _H2 ,
Thereafter, when the temperature detected by the first temperature sensor 11 reaches this dry-up condition _H2 , the rice cooking heater 9 is powered off to end the rice cooking process.

The operation of the present invention constructed as above will be explained with reference to FIG. When a rice cooking start switch (not shown) is turned on, electricity is supplied to the rice cooking heater 9, thereby heating the pot 8 and the contents (rice and water) in the pot 8. In FIG. 3, A indicates the pot temperature detected by the first temperature sensor 11, and B indicates the change in steam temperature detected by the second temperature sensor 13. Note that the pot temperature A depends on the adhesion between the first temperature sensor 11 and the heat sensitive part 10 or the heat sensitive part 1.
Due to factors such as the contact between the boiler and the outer bottom of the pot 8 or fluctuations in the power supply voltage, the temperature does not change uniformly, and the temperature after boiling also varies as shown by A ₁ , A ₂ , and A ₃ . It is occurring.

When the contents in the pot 8 are heated and the water reaches boiling temperature, the temperature of the steam passing through the steam vent tube 7 rises rapidly and stabilizes at approximately 100°C, which then becomes the second temperature. The temperature sensor 13 detects the boiling point P. At this time, the pan temperature detected by the first temperature sensor 11 varies as described above, but is also stable. Then, the control means 14 controls the pot temperature detected by the first temperature sensor 11 at the time when a predetermined time T has elapsed from when the second temperature sensor 13 detects the boiling point P until the water in the pot 8 disappears. and use this as the reference temperature.
_H1 , and a temperature obtained by adding a predetermined temperature α (for example, 10° C.) required for dry-up to this reference temperature _H1 is calculated as a dry-up condition _H2 . Then, when the temperature detected by the first temperature sensor 11 reaches the dry-up condition _H2 , the control means 14 turns off the power to the rice cooking heater 9 and ends the rice cooking process. Incidentally, following this rice cooking process, the rice cooking heater clock or other heater may be energized again in order to perform a unilateral process or a warming process. Further, the predetermined time T is the time required for the moisture in the pot 8 to disappear;
The amount of rice to be cooked is varied from 0 to 240 seconds in proportion to the amount of rice cooked in the pot. If the amount of rice to be cooked is small, T can be set to be shorter.

In this way, the pot temperature detected by the first temperature sensor 11 varies depending on the arrangement state of the first temperature sensor 11 and the contact state with the heat-sensitive part 10 of the pot 8, and the pot temperature and the pot temperature vary. However, the present invention is based on the generation of steam detected by the second temperature sensor 13. Since the boiling point P is detected, the boiling point P of the water temperature in the pot 8 can be detected accurately. Even if the pan temperature detected by the first temperature sensor 11 varies, the rate of temperature increase after the reference temperature _H1 is almost the same, so it cannot be used to detect a relative temperature increase, that is, the predetermined temperature α. , Therefore, detect the pot temperature H ₁ at the time when a predetermined time T has elapsed from the boiling point P,
If the temperature obtained by adding the predetermined temperature α to the pot temperature H ₁ is set as the dry-up condition H ₂ , the dry-up state of the contents in the pot 8 can be accurately detected. Therefore,
When the temperature detected by the first temperature sensor 11 reaches this dry-up condition _H2 , when the rice cooking heater 9 is turned off to end the rice cooking process, the inside of the pot 8 is in an accurate dry-up condition, and the dry-up temperature is It is possible to always obtain stable cooked rice by preventing the rice from becoming sticky or excessively burnt due to insufficient heat or excessive heating. In addition, after detecting the boiling point P, a _second
The reason why the second temperature sensor 13 is not used is that steam is not necessarily generated after the predetermined time T when the moisture in the pot 8 disappears, and the second temperature sensor 13 is not used.
This means that detection cannot be performed.

Above, one embodiment of the present invention has been described in detail.
It can be modified as appropriate within the scope of the gist of the present invention. For example, although a temperature sensor that detects the temperature of steam is used as the steam generation detection means, since steam is vigorously jetted out during boiling, it is also possible to use a pressure switch or the like that performs a switch operation based on the jetting pressure.

[Effects of the invention] As detailed above, according to the invention, the boiling point is detected by the steam generation detection means, so even if the correlation between the detected temperature of the pot and the water temperature in the pot deteriorates, the accuracy can be maintained. To provide a rice cooker capable of stably cooking rice by detecting a dry-up state.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is a block diagram, and Figure 3 is a temperature change characteristic diagram of the pot and steam. 8... Pot, 9... Rice cooking heater, 11... First temperature sensor (pan temperature detection means), 13... Second temperature sensor (steam generation detection means), 14... Control means.

Claims (1)

[Scope of utility model registration request] a pot temperature detection means for detecting the temperature of the pot; a steam generation detection means for detecting the generation of steam in the pot;
The temperature of the pan detected by the pan temperature detection means after a predetermined time has elapsed since the steam generation detection means detects the generation of steam is set as the reference temperature, and the temperature obtained by adding a predetermined temperature to this reference temperature is set as the dry-up condition. A rice cooker characterized by comprising: a control means for setting a temperature of the rice cooker and cutting off power to the rice cooking heater when the temperature of the pot detected by the pot temperature detection means reaches the dry-up condition.