JPH0789990B2 - Electric rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention relates to an electric rice cooker having a pan heating means for heating a pan and controlling the input of the pan heating means to cook rice. .

(Prior Art) A general structure of such an electric rice cooker is shown in FIG.
1 is a rice cooker body, and this rice cooker body 1 is an outer frame 2 and an inner frame 3
And a rice cooking heater 4 as a pot heating means and a temperature detector 5 are provided at the bottom of the inner frame 3, and the rice cooking heater 4 is provided at the bottom of the outer frame 2 based on the temperature detection information from the temperature detector 5. An electronic circuit unit 6 for controlling the input of is provided. A pot 7 is removably housed in the inner frame 3, and an opening at the upper end of the pot 7 is closed by a lid 8.

And when cooking rice, remove the pan 7 from the inner frame 3
A necessary amount of rice washed with water and a predetermined amount of water according to the amount of this rice are stored, and then the pot 7 is inserted into the inner frame 3 and its opening is closed by the lid body 8 in this state. Then, a start switch (not shown) is turned on 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 after a predetermined process.

Figure 3 shows the process of cooking rice, which shows the relationship between the temperature change of the pan with the passage of time and the input state of the rice cooking heater. First, the rice cooking heater is energized continuously, and the temperature of the pan changes accordingly. Gradually increases. Then, the amount of rice in the pot is detected based on the elapsed time when the pot temperature changes from 70 ° C to 80 ° C. This detection is calculated from the time T required until the pot temperature rises (D) from 70 ° C to 80 ° C. That is, 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. Therefore, the amount of rice is determined based on this time T.

Boiling is detected after the pot temperature approaches 100 ° C. This boiling detection utilizes the point that when the water in the pot starts to boil, the latent heat of vaporization suppresses the rise in the temperature of the pot and becomes almost constant. In other words, from the point P ₀ after the pot approaches 100 ° C, when the amount of rice is determined to be small by the rice amount detection (A curve), it is determined to be medium for 60 seconds. (B curve) for 100 seconds,
Similarly, when it is determined to be large (C curve), the time when the temperature rise rate of the pot in 140 seconds becomes 5deg or less is detected, and it is determined that the water in the pot has boiled by this detection. Then, in response to the detection of such boiling, the input to the rice cooking heater is switched from continuous energization to intermittent energization with a duty ratio of 50%,
In this heating state, boiling in the pan will continue stably. And when the water in the pan is almost evaporated, the temperature of the pan rises again,
When the temperature reaches approximately 120 ° C, the rice is cooked and the rice cooking heater is de-energized.

(Problems to be solved by the invention) As described above, conventionally, 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 pan to cook rice. Since the input of the heater is controlled, there is a problem in that the structure is complicated and expensive.

The present invention has been made in view of such a point, and an object thereof is to provide an electric rice cooker capable of properly cooking rice without detecting the amount of rice. It is in.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve such an object, the present invention has a pot for cooking rice, a pot heating means for heating the pot, and a temperature for detecting the temperature of the pot. Detecting means, and a control means for controlling the amount of pot heating by the pot heating means according to the temperature of the pot, by the control means, the temperature of the pot approaches the boiling point by continuous energization of the pot heating means in advance. It detects the time when the temperature rise rate of the pan in the set fixed time is below a predetermined value, and according to this detection the power supply to the pan heating means is cut off for a fixed time, and the temperature decrease rate of the pan during this cutoff When the temperature is higher than the specified value, the pot heating means is continuously energized and the same process is repeated.If the temperature decrease rate of the pan does not reach the specified value while the pot heating means is de-energized, the energization rate of the pot heating means is changed. It is designed so that electricity is dropped until the rice is cooked.

(Function) The amount of rice in the pan depends on whether or not the temperature rise rate of the pan becomes a predetermined value or less at a preset time after the temperature of the pan approaches the boiling point due to continuous energization of the pan heating means. Regardless of this, the start of boiling is detected, and therefore proper rice cooking can be achieved without the need for conventional rice amount detecting means.

(Example) Hereinafter, the Example of this invention is described.

FIG. 1 (a) shows the respective rice cooking steps when the amount of rice to be cooked is large, FIG. 1 (b) is the same, and FIG. 1 (c) is the same. In the rice cooking process of FIG. 1 (a), the rice cooking heater as the pan heating means is continuously energized at the start of rice cooking, and the temperature of the pan gradually rises accordingly. Then, the time when the temperature rise rate of the pot becomes 5deg or less within a preset fixed time, for example, 5 minutes after the pot approaches 100 ° C (boiling detection A ₁ ), is detected. Accordingly, the power supply to the rice cooking heater is temporarily cut off. Here, in this cooking process, since the amount of rice in the pan is large, the boiling in the pan was not sufficient even at the time of boiling detection A ₁ , and therefore the temperature of the pan was cut off when the electricity to the rice cooking heater was cut off. Falls relatively quickly. Then, when the temperature decrease rate of the pan in a certain time, for example, 60 seconds, is 3 deg or more after the power to the rice cooking heater is cut off, the rice cooking heater is continuously energized again after the elapse of the certain time. If the rate of temperature decrease of the pan during a certain time when the power of the rice cooking heater is cut off is extremely large, it is not preferable for rice cooking performance, so energizing the rice cooking heater is started when the temperature of the pan decreases to a certain temperature .

The temperature of the pan rises again when the rice cooking heater is turned on. Then, the same boiling detections A ₂ and A ₃ as described above and the interruption of power to the rice cooking heater are repeated, and such boiling detection is performed.
When the amount of water in the pan decreases due to the heating at A ₂ and A ₃ , and the temperature decrease rate of the pan does not exceed the specified value (3 deg) when the rice heater is de-energized after boiling detection A ₃ , the rice is cooked. Energization to the heater is switched to, for example, intermittent energization with a duty ratio of 50%, whereby boiling in the pot continues. Then, when the water in the pan is almost completely evaporated, the temperature of the pan rises rapidly, and when the temperature rises, the cooked rice is detected and the rice heater is de-energized.

On the other hand, in the rice cooking process of Fig. 1 (b), the amount of rice in the pan is medium, so the temperature decrease rate of the pan will not exceed the specified value at the _second boiling detection A2. Therefore, after the boiling detection A _{2, the} energization to the rice cooking heater is switched to the intermittent energization with the duty ratio of 50%, and the process is shifted to the cooking. Further, in the rice cooking process of FIG. 1 (c), since the amount of rice in the pan is small, the temperature decrease rate of the pan will not exceed the predetermined value in the _first boiling detection A ₁ , and therefore Boiling detection A ₁
After that, the energization to the rice cooking heater is switched to intermittent energization with a duty ratio of 50%, and the process shifts to cooking.

In this way, regardless of whether the amount of rice in the pan is large, medium, or small, proper rice cooking is achieved without the need for conventional rice amount detection means.

[Effects of the Invention] As described above, according to the present invention, there is an advantage that the conventional rice amount detecting means is unnecessary, and therefore the configuration is simple and the cost is low.

[Brief description of drawings]

1 (a), (b) and (c) are graphs showing a rice cooking process by the electric rice cooker according to one embodiment of the present invention, and FIG. 2 is a sectional view showing a general structure of the electric rice cooker. FIG. 3 is a graph showing a conventional rice cooking process. 4 ... rice cooking heater (pot heating means), 5 ... temperature detector,
6 ... Electronic circuit unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Tamaki 2570 1 Gosuda, Kamo City, Niigata Prefecture 1570 Toshiba Heat Appliance Co., Ltd. (72) Inventor Satoru Tsukada 2570 1 Gosuda, Kamo City, Niigata Prefecture Toshiba Heat Appliance Incorporated (72) Inventor Morio Asahi 4-21, Yoshihara-cho, Nishi-ku, Nagoya-shi, Aichi Prefecture Nagoya factory (56) Reference JP 62-38114 (JP, A) JP 62-38117 ( JP, A)

Claims (1)

[Claims] 1. A pot for cooking rice, a pot heating means for heating the pot, a temperature detecting means for detecting the temperature of the pot, and a control means for controlling the pot heating amount by the pot heating means according to the temperature of the pot. The control means detects a time point when the temperature rise rate of the pot becomes a predetermined value or less at a preset constant time after the temperature of the pot approaches the boiling point due to continuous energization of the pot heating means. Depending on this detection, the heating of the pot heating means is interrupted for a certain period of time, and if the temperature decrease rate of the pot during this interruption is above a predetermined value, the pot heating means is continuously energized again and the same process is repeated. An electric rice cooker characterized in that when the temperature decrease rate of the pan does not reach a predetermined value while the heating means is de-energized, the pan heating means is de-energized to energize until the rice is cooked.