JPS587285B2 - electric rice cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric rice cooker (including an electronic jar rice cooker) that has a function equivalent to the "place fire" function in rice cooking using a stove.

The same applies hereafter). In conventional electric rice cookers, the rice heater is turned off immediately after the rice is boiled, and thereafter the rice is simply steamed by residual heat, which has the following drawbacks.

In other words, if you finish cooking 2 to 4 minutes after boiling, the water sucked into the rice grains will make the rice grains have no fluidity and will appear to be solid, but there will still be some water inside the pot. Excess water remains, and this water is not completely removed by steaming using the residual heat that is carried out after the rice is cooked, so only sticky, raw-cooked rice is obtained.

In addition, in the steaming process using residual heat, the rice temperature decreases relatively quickly and gelatinization of starch in the rice grains stops, so gelatinization does not proceed to the core of the rice grains, making it impossible to obtain delicious rice ( Note that once gelatinization has stopped, gelatinization does not proceed even if reheated).

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an electric rice cooker that heats rice again after a temporary non-heating state after boiling, that is, heats the rice over a flame.

The present invention will be explained below based on drawings showing embodiments thereof.

Figure 1 shows a lower section of the electric rice cooker according to the present invention;
2 is an outer pot, 2 is a disk-shaped hot plate fixed to the upper surface of the bottom wall 1a of the outer pot 1, and 3 is a main heater, in which a sheathed heater of about 600 W is cast in an annular shape inside the hot plate 2. There is.

4 is a non-resetting thermal switch (hereinafter referred to as a rice cooking switch) whose operating temperature T1 is set to match the ambient temperature corresponding to the end temperature of rice cooking, It is located and installed inside the hole.

Reference numeral 41 indicates a contact point of the rice cooking switch 4, which is closed when the operating rod 42 that moves up and down is in the raised position shown by the solid line.

Reference numeral 5 denotes an inner pot that is detachably housed in the outer pot 1, and a heat-sensitive part 5b provided at the center of the lower surface of the bottom wall 5a is connected to the heat-sensitive part 43 of the rice-cooking switch 4 and to the bottom wall other than the central part. The lower surface of 5a is in thermally conductive contact with the upper surface of hot plate 2, respectively.

Reference numeral 6 denotes a lever that sets the operating rod 42 of the rice cooking switch 4 to the raised position, and is pivoted by a shaft 7, the tip of which is connected to the lower end of the operating rod 42 with a pin, etc., and the rear end is connected to the rice cooker main body case. The lever 6 protrudes from an opening 9 formed in the side wall of the lever 8 so that the lever 6 can be operated from the outside.

Reference numeral 10 denotes a thermal reed switch that is thermally attached to the lower surface of the hot plate 2, and is closed when the ambient temperature falls below a temperature T2, which is slightly lower than the operating temperature T1 of the rice cooking switch 4. It is supposed to be done.

It is preferable that the temperature T2 is set at a temperature that matches the temperature of the thermal reed switch installation site at least 2 to 3 minutes after the power supply to the main heater is stopped due to boiling of the cooked rice. .

11 is a time switch (motor timer) attached to the side wall of the rice cooker main body case 8, and its contacts are automatically opened when a preset period of time has elapsed after the start of power supply to the motor. .

This set time is determined depending on the amount of rice to be cooked, etc., but the time is set so that the contact 111 (see Fig. 2) is disconnected when, for example, about 5 minutes have passed after the start of the heating process as described below. In this case, it is very convenient because the heating time itself can be controlled.

FIG. 2 shows the electric circuit of the electric rice cooker according to the present invention.

This electric circuit consists of the contact 41 of the rice cooking switch and the main heater 3.
are connected in series to form a rice cooking circuit A, and a series circuit formed by connecting the thermal reed switch 10, the contact 111 of the time switch 11, and the diode 13 in series is connected in parallel to the contact 41 of the rice cooking switch, A fire heating circuit B is formed together with the main heater 3.

In the illustrated embodiment, the time switch 11 is inserted into the series circuit of the fire heating circuit B so as to be connected in series.

The electric rice cooker of the present invention configured as described above operates as follows.

First, the set time of the time switch 11 is set to the time required for heating over the fire, and the rear end of the lever 6 is manually pushed down.

When the rear end of the lever 6 is pressed down, the operating rod 42 is raised and the contact 41 of the rice cooking switch 4 is turned on, so that the rice cooking circuit A is energized and heating of rice by the main heater 3 starts.

Since the main heater 3 is directly supplied with the power supplied to the AC power terminal, the amount of heat generated by the main heater 3 is large.

At the start of rice cooking, the ambient temperature of the thermal reed switch 10 is lower than T2, so the switch 10
is closed.

However, in this circuit state, the contact 4 of the rice cooking switch 4
1 is closed, no voltage is applied to the time switch 11 and timekeeping is performed. The motor is not driven.

When a certain period of time has passed after the start of rice cooking and the rice has boiled and the ambient temperature has reached the operating temperature T1 (the rice temperature at this time is approximately 98°C), the thermal rice cooking switch 4 senses this and is activated. Since the rod 42 is lowered and the tip side of the lever 6 is pushed down, the contact 41 of the rice cooking switch opens (the dashed line in FIG. 1 indicates this state), and the cooking and heating ends (see FIG. 3).

Immediately after the rice cooking is completed, the ambient temperature is T2 or higher, so the thermal reed switch 10 is open, and the fire heating circuit B is not energized.

Therefore, in this state, no heating is performed by the fire, and the time switch 11 does not start timing operation yet.

As shown in FIG. 3, in this non-heated state, the rice temperature decreases, so excess free water interposed between the rice grains condenses on the surface of the rice grains and the bottom wall of the inner pot.

Then, when the ambient temperature falls to the operating temperature T2 of the thermal reed switch 16, the switch 10 is closed and the above-mentioned fire heating circuit B becomes energized.

In this circuit state, as will be described later, the main heater 3 starts heating the main heater 3 again with a small amount of heat generated, and at the same time, of course, a current half-wave rectified by the diode 13 flows through the time switch 11 and starts timing operation.

Heating is done by the thermal reed switch 10.
This is done while the temperature is kept at a roughly constant temperature.

Moreover, since only about half of the power supplied to the power terminal by the diode 13 is supplied to the main heater 3 of the above-mentioned overheat heating circuit B, overheating after the rice has boiled is performed slowly with a small amount of heat generated. .

Then, when the time set in advance in the time switch 11 has elapsed, the contact 111 of the time switch 11 opens, and the heating over the flame ends (see FIG. 3).

By heating in this way, excess water that has condensed can be evaporated and completely removed from the cooked rice, so the amount of water in the rice can be maintained at an appropriate moisture level (equilibrium moisture). This allows for an ideal steaming process.

Further, in the non-heating state, unnecessary heating is omitted, and efficient heating can be obtained.

The electric circuit of the electronic jar rice cooker shown in FIG. 4 is such that the timing motor of the time switch 11 is not inserted in series into the series circuit of the fire heating circuit B, but is connected in parallel to the contact 41 of the rice cooking switch. and rice cooking circuit A.
This circuit differs from the circuit shown in FIG. 2 in that a heat insulating circuit 12 is connected in parallel with the circuit shown in FIG.

In the case of the electric circuit shown in Fig. 4, the contact 41 of the rice cooking switch is closed during cooking and heating, so no voltage is applied to the motor of the time switch 11 and the time switch 11 does not measure time. When the rice boils and the contact 41 of the rice cooking switch opens as described above, voltage is applied to the motor and the time switch 11 starts measuring time.

On the other hand, immediately after the heating of rice is completed, the thermal reed switch 10 is open as described above and the heating circuit B is also in a non-conductive state, but when the ambient temperature drops to the operating temperature T2 and the thermal reed switch 10 is closed. The ignition heating circuit B becomes conductive, and the ignition heating by the main heater 3 is started.

As described above, this heating by the diode 13 generates a small amount of heat.

During this heating process, the current half-wave rectified by the diode 13 flows to the motor of the time switch 11, so the time switch 11 continues to measure time. Heating over a standing fire will be carried out.

In the electric circuit shown in FIG. 4, the time switch 11 starts its timing operation immediately after the end of cooking and heating, as described above, so the time setting is set in the non-heating state (for example, 2 to 2).
It is necessary to estimate the total time of cooking (3 minutes) and heating over a standing fire (for example, about 5 minutes), and then cook the rice appropriately depending on the amount of rice to be cooked.

It will be understood without a detailed explanation that the electronic jar rice cooker equipped with the electric circuit shown in FIG. 4 can have basically the same functions and effects as the embodiment shown in FIG. 2.

FIG. 5 shows an electric circuit of an electronic jar rice cooker which is an embodiment of another aspect of the present invention.

This electric circuit does not insert the timing motor of the time switch 11 in series into the series circuit of the fire heating circuit B, but connects it to the series circuit consisting of the diode 13 and the thermal reed switch 10 of the fire heating circuit B. The difference is that a series circuit consisting of a timekeeping motor 11 and a thermal reed switch 100 that closes when the ambient temperature falls below temperature T2 is connected in parallel with the thermal reed switch 10, as shown in FIG. The circuit is basically the same as the one shown above.

In the case of the electric circuit shown in FIG. 5, the contact 41 of the rice cooking switch is closed during cooking and heating, so no voltage is applied to the motor of the time switch 11 and the time switch 11 does not measure time.

When the rice boils and the ambient temperature reaches the operating temperature T1, the contact 41 of the rice cooking switch opens as described above, but since the thermal reed switch 100 is open at this time, the timing operation does not start yet.

When the ambient temperature falls to the operating temperature T2 and the thermal reed switch 10, 1100 closes, current flows to the main heater 3 through the time switch 111 and at the same time, current flows to the motor of the time switch 11 to start heating. Timing operation starts.

Therefore, this heating is continued until the contact 111 of the retime switch opens after a preset time has elapsed.

The electronic jar rice cooker of the present invention equipped with the electric circuit shown in FIG.
As in the case of the embodiment shown in FIG. 2, the time switch 11 starts the timing operation from the start of heating over the overheating, so there is an advantage that the overheating time itself can be easily controlled, as well as other effects. In this respect, it is basically the same as the embodiment shown in FIG.

As described above, the electric rice cooker according to the present invention temporarily creates a non-heating state after boiling the rice, condenses the excess water interposed between the rice grains, and then heats the rice again over low heat and then switches the time switch. By doing this for the correct amount of time, the excess water will completely evaporate without burning the rice, resulting in rice that is neither sticky nor raw.

In addition, since the temperature of the rice does not drop rapidly after heating the rice, the gelatinization of the lees in the rice grains proceeds to the core, resulting in delicious rice.

Further, the function of the thermal reed switch 10 makes it possible to prevent the temperature from rising too high due to heating over a fire, and furthermore, it is possible to omit the extra heating that is performed immediately after the end of cooking rice, and to obtain a non-heating state.

In the present invention, the thermal reed switch is attached to an appropriate position, but when it is attached to a hot plate where temperature changes are large as shown in the embodiment diagram, its operation becomes reliable.

Note that in the present invention, the time switch is not limited to a motor timer.

Further, in the embodiment circuit shown in FIG. 2, the series circuit of the fire heating circuit may not include a diode.

That is, in the circuits of FIGS. 4 and 5, the diode 1
3 is indispensable for extracting the clocking motor drive voltage of the time switch 11, but in the embodiment circuit of FIG. It is performed with the same calorific value as the heating, but as mentioned above, the thermal reed switch 10 prevents the temperature from rising too much due to the heating.
The diode 13 can be omitted from the illustrated embodiment circuit.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view of the lower part of the electric rice cooker according to the present invention;
Figure 2 is its electric circuit diagram, Figure 3 is a graph showing temporal changes in rice temperature, Figure 4 is an electric path diagram of the electronic jar rice cooker,
FIG. 5 is an electric circuit diagram of another embodiment of the electronic jar rice cooker according to the present invention. 1...Outer pot, 2...Hot plate, 3...
...Main heater, 4...Rice cooking switch, 10...
...Thermal reed switch, 11...Time switch, 13...Diode, 41...
・5 Rice cooking switch contacts, 111...Time switch contacts, A...Rice cooking circuit, B...
- Fire heating circuit.

Claims (1)

[Claims] 1. In an electric rice cooker equipped with a rice cooking circuit in which the main heater is connected in series with a non-resetting type thermal rice cooking switch that opens when the rice boils, for the rice cooking switch,
A series circuit consisting of a time switch contact and a temperature-sensitive switch, or a series circuit consisting of a time switch contact, a temperature-sensing switch, and a diode are connected in parallel, and the temperature-sensitive switch changes the ambient temperature when the rice cooking switch is turned off. This is a switch that closes when the temperature drops to the operating temperature, and after the end of cooking and heating, the temperature-sensitive switch closes and the rice-cooking heater starts heating the rice at a predetermined temperature.
An electric rice cooker characterized in that the time switch simultaneously starts a timing operation and ends the heating over a predetermined flame after a predetermined period of time has elapsed.