JPH01320021A - Electric rice boiling machine - Google Patents

Abstract

PURPOSE:To properly boil rice without requiring detection of the quantity of rice by detecting start of boiling based on if the temperature increase rate in the pot gets under a predetermined value within a preset time after the temperature of the pot gets close to 100 deg.C or not. CONSTITUTION:For starting boiling rice, a rice boiling heater is first energized continuously, and the temperature of a pot is increased gradually. The timing when the temperature increase rate in the pot becomes less than 5deg., for example, in a preset time, that is 5min. for example, after the pot temperature reaches close to 100 deg.C is detected (a boil detection A1), and energization is broken once. If the temperature decrease rate in the pot for a predetermined time, that is 60sec., for example, after energization of the rice boiling heater is broken is more than 3deg., the heater is again energized continuously. In case the temperature decrease rate in the pot at the time of breakage of energization to the rice boiling heater after a boiling detection A3 is not more than a predetermined value 3deg., energization to the rice boiling heater is switched to a discontinuous energization of an energization rate of 50%, for example, so boiling in the pot is continued. If water in the pot is almost vaporized up, the temperature in the pot increases rapidly, and boil up of rice at this temperature increase is detected, when energization to the rice boiling heater is broken.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an electric rice cooker that is equipped with a rice heater that heats a pot and that cooks rice by controlling the human power of the rice heater.

(Prior art) The general structure of such an electric rice cooker is shown in Figure 2.
1 is the rice cooker body, and this rice cooker body 1 has an outer frame 2 and an inner frame 3.
A rice cooking heater 4 and a temperature sensor 5 are provided at the bottom of the inner frame 3, and the temperature sensor 5 is provided at the bottom of the outer frame 2.
An electronic circuit unit 6 is provided to control the input to the rice cooking heater 4 based on temperature detection information etc. A pot 7 is removably housed in the inner frame 3.
The opening at the upper end is closed with a lid 8.

When cooking rice, take out the pot 7 from the inner frame 3 and
The required amount of washed rice and a predetermined amount of water corresponding to the rice melon are placed inside the inner frame 3, and then the pot 7 is inserted into the inner frame 3, the opening is closed with the lid body 8, and the pot 7 is placed in this state. Turn on the start switch (not shown) manually or by a timer. In response to this, the input to the rice cooking heater 4 is controlled via the electronic circuit unit 6, and the rice is cooked through a predetermined process.

Figure 3 shows the rice cooking process, which shows the relationship between the temperature change in the pot over time and the human power status of the rice cooking heater. gradually increases. And the temperature of the pot is 70℃ to 80℃.
The amount of rice in the pot is detected based on the elapsed time when the temperature changes to ℃.

This detection is determined from the time T required for the temperature of the pot to rise (D) from 70°C to 80°C. In other words, when the amount of rice is small, the time T is short, and when the amount of rice is large, the time T is long, so the amount of rice is determined based on this time T.

Boiling is detected after the temperature of the pot approaches 100°C. This boiling detection utilizes the fact that when the water in the pot starts to boil, the latent heat of vaporization suppresses the temperature rise in the pot and keeps it almost constant. In other words, the temperature of the pot is approximately 100°C.
Later P. approached. From the point in time, if the amount is determined to be small by the rice amount detection, 60 seconds (a (A curve)), and 10 seconds if it is determined to be medium (curve 8).
0 seconds, and when it is also judged as large (C curve), it is 14
The time point when the temperature rise rate of the pot in 0 seconds becomes 5 degrees or less is detected, and upon this detection, it is determined that the water in the pot has boiled. In response to such detection of boiling, the input to the rice cooking heater is switched from continuous energization to intermittent energization with a 50% energization rate, and boiling in the pot continues stably in this heating state. When most of the water in the pot has evaporated, the temperature of the pot rises again, and when it reaches 120 degrees Celsius, the rice is cooked and the power to the rice cooker is turned off.

(Problem to be solved by the invention) In this way, in the conventional method, the amount of rice to be cooked is first detected, and the start of boiling is detected from the relationship between the detected amount of rice and the temperature rise rate of the pot, and then the rice is cooked. The input of the heater is controlled, which has the disadvantage of a complicated configuration and a high cost (11b).This invention was made with attention to these points.
The purpose is to provide an electric rice cooker that can properly cook rice without requiring detection of rice melon.

[Structure of the invention] (Means for solving the problem) In order to achieve the above object, the present invention includes a rice cooking pot, a rice cooking heater for heating the pot, and a sensor for detecting the temperature of the pot. and a control means for controlling input to the rice-cooking heater according to the temperature of the rice-cooking pot, the control means controlling the temperature of the rice-cooking heater for a predetermined period of time after the temperature of the pot approaches 100° C. by continuous energization of the rice-cooking heater. Detects the point in time when the temperature rise rate of the pot becomes less than a predetermined value, and in response to this detection, the power supply to the rice cooking heater is cut off for a certain period of time, and the temperature drop rate of the pot during this cutoff is lower than the predetermined value. If the rice cooking heater is energized continuously for 1 [f times and the same process is repeated, and if the temperature reduction rate of the pot does not reach the predetermined value while the rice cooking heater is turned off, the energization rate of the rice cooking heater is reduced and the rice is heated. The electricity is turned on until the rice is cooked.

(Function) The temperature of the rice in the pot is determined by whether or not the temperature rise rate of the pot is below a predetermined value in a set period of time after the temperature of the pot approaches 100℃ due to continuous energization of the rice cooking heater. The start of boiling is detected regardless of the amount of rice, so proper rice cooking can be achieved without the need for conventional rice bran detection means.

(Example) Examples of the present invention will be described below.

FIG. 1(a) shows the rice cooking process when the amount of rice to be cooked is large, FIG. 1(b) shows the rice cooking process when the amount of rice to be cooked is medium, and FIG. 1(c) shows the rice cooking process when the amount of rice to be cooked is small. In the rice cooking process shown in FIG. 1(a), the rice cooking heater is first continuously energized at the start of rice cooking, and the temperature of the pot gradually rises accordingly. Then, it is detected (boiling detection A1) whether the temperature rise rate of the pot becomes 5 deg or less in a preset period of time, for example, 5 minutes after the pot approaches 100 degrees Celsius. Accordingly, the power supply to the rice cooking heater is temporarily cut off. Here, in this rice cooking process, since the amount of rice in the pot is large, the boiling in the pot is not sufficient even at the time of boiling detection A1, and as a result, the temperature of the pot decreases as the electricity to the rice cooking heater is cut off. Declines relatively quickly. If the temperature decrease rate of the pot is 3 degrees or more in a certain period of time, for example, 60 seconds after the rice-cooking heater is de-energized, the rice-cooking heater is continuously energized again after the certain period of time has elapsed. In addition,
If the temperature drop rate of the pot over a certain period of time during which electricity to the rice-cooking heater is cut off is extremely large, this is unfavorable in terms of rice-cooking performance, so energization of the rice-cooking heater is started when the temperature of the pot drops to a certain temperature.

The temperature of the pot rises again by the start of electricity supply to the rice cooking heater. Then, the same boiling detections A2 and A3 as described above and the interruption of electricity to the rice cooking heater are repeated, and such boiling detections A2 and A3 are repeated. The amount of water in the pot decreases during heating at A3, and the amount of water in the pot decreases when power is cut off to the rice cooker after boiling is detected at A3. When the m-degree reduction rate does not exceed a predetermined value (3 degrees), the energization to the rice cooking heater is switched to intermittent energization with an energization rate of 5026, thereby continuing boiling in the pot. When most of the water in the pot evaporates, the temperature of the pot rises rapidly, and this rise in temperature detects that the rice is cooked, and the rice heater is turned off.

On the other hand, in the rice cooking process shown in FIG. 1(b), since rice 2 in the pot is inside, the temperature drop rate of the pot does not exceed a predetermined value at the second boiling detection A2. Therefore, after boiling detection A2, the energization rate to the rice cooking heater is 50.
It switches to intermittent energization of % and moves to cooking.

Furthermore, in the rice cooking process shown in FIG. 1(C), since the rice melon in the pot is small, the temperature drop rate of the pot does not exceed a predetermined value at the boiling detection A1 of 1]. Therefore, after boiling detection Al, the energization rate to the rice cooking heater is 509.
It is switched to intermittent energization in Step 6, and the cooking begins.

In this way, regardless of whether the amount of rice in the pot is large, medium, or small, proper rice cooking can be achieved without requiring a conventional rice amount detection means.

[Effects of the Invention] As explained above, according to the present invention, there is no need for a conventional rice amount detection means, and therefore there is an advantage that the structure is simple and inexpensive.

[Brief explanation of the drawing]

FIGS. 1(a), (b), and (c) are graphs showing the rice cooking process by an electric rice cooker according to an embodiment of the present invention, and FIG. 2 is a sectional view showing the general structure of the electric rice cooker. FIG. 3 is a graph diagram showing a conventional rice cooking process. 4...Rice cooking heater, 5...Temperature detector, 6...Electronic circuit unit. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] It comprises a rice cooking pot, a rice cooking heater for heating the pot, a detection means for detecting the temperature of the pot, and a control means for controlling input to the rice cooking heater according to the temperature of the pot, and the control means , the temperature of the pot reaches 100 when the rice cooker heater is continuously energized.
It detects the point in time when the temperature rise rate of the pot becomes less than a predetermined value in a preset period of time after approaching the temperature of When the temperature decrease rate of the pot is equal to or higher than a predetermined value, the rice cooker heater is continuously energized again and the same process is repeated, and when the temperature decrease rate of the pot does not reach the predetermined value while the rice cooker heater is turned off, the rice cooker heater is energized. This electric rice cooker features electricity at a reduced rate until the rice is cooked.