JPS6159724B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric rice cooker (including an electronic jar rice cooker; the same applies hereinafter) having a function equivalent to the "place fire" function of rice cooking in a stove.

Conventional electric rice cookers have the following drawbacks because the rice heater turns off when the rice boils, and after that the rice is simply steamed using residual heat. In other words, at the point of boiling, the water sucked into the rice grains makes the grains themselves appear solid with no fluidity, but there is still excess water left in the pot, and this water is absorbed by the residual heat. Steaming alone does not completely remove the phlegm, resulting in only sticky, raw-cooked rice.

In addition, in the steaming process using residual heat, the rice temperature drops relatively quickly and gelatinization of starch in the rice grains stops, so gelatinization does not progress to the core of the rice grains, resulting in delicious rice. (In addition,
Once gelatinization has stopped, gelatinization does not proceed even if reheated).

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electric rice cooker that heats rice over a fire after boiling it.

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

FIG. 1 shows a cross section of the lower part of the electric rice cooker according to the present invention, where 1 is an outer pot, 2 is a disc-shaped hot plate fixed to the upper surface of the bottom wall 1a of the outer pot 1, and 3 is a heater.
A sheathed heater of about 600 W is cast into the hot plate 2 in an annular shape. 4 is a non-resetting type thermal switch (hereinafter referred to as rice cooking switch) whose operating temperature T ₁ 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, which moves up and down, is in the raised position shown by the solid line. Reference numeral 5 indicates a capacitor switch, and 51 indicates its contact, which is open when the operating rod 42 is in the raised position shown by the solid line. In other words, rice cooker switch 4
and capacitor switch 5 are in such a relationship that when one is closed, the other is opened. 6 is an inner pot removably housed in the outer pot 1, and its bottom wall 6
Approximately the center part 6b of a is the heat sensitive part 4 of the rice cooker switch 4
3 and the lower surface of the bottom wall 6a other than the central portion 6b are in heat conductive contact with the upper surface of the hot plate 2, respectively. 7
is a lever for setting the operating rod 42 of the rice cooking switch 4 to the raised position, and is pivotally supported by the shaft 8, its tip 7a is connected to the lower end of the operating rod 42 with a pin or the like, and its rear end 7b is rice cooker main case 9
The lever 7 protrudes from an opening 10 formed in the side wall of the lever 7 so that the lever 7 can be operated from the outside. 1
1 is a temperature-sensitive switch consisting of a thermal reed switch heat-conductively attached to the lower surface of the heating plate 2, and the ambient temperature thereof is a temperature slightly lower than that corresponding to the operating temperature _T1 of the rice cooking switch 4. _T2
It closes when the temperature is lower than that, and the temperature is lower than that.
It is designed to open when T is below ₃ . The temperature _T2 is preferably set at a temperature that matches the temperature at the temperature-sensitive switch attachment point at least 2 to 3 minutes after the power supply to the main heater is stopped due to boiling of the cooked rice. . Further, the temperature T ₃ may be higher than the atmospheric temperature at the start of rice cooking. Reference numeral 12 denotes a manually operated automatic return type fire button attached to the side wall of the rice cooker main body case 9, and is used to charge a capacitor to be described later. Reference numeral 13 denotes a bimetal, which is held by a holder 14, the tip of which comes into contact with the lower end of the operating rod 42, and when the bimetal 13 bends upward, the operating rod 42 rises and the rice cooking switch 4 is closed. It's summery. 15 is a micro heater;
It is wound around the bimetal 13 (see Fig. 4).

FIG. 2 shows an electric circuit of an electric rice cooker according to the present invention. Contact point 4 between the heater 3 and the rice cooking switch 4
1 are connected in series, and the series circuit is
Connected to AC100V power supply. 16 is a charging circuit in which a capacitor 17, a contact 51 of the capacitor switch 5, a fire button 12, and a diode 21 are connected in series, and is connected to an AC 100V power source. Reference numeral 12 denotes a manually operated automatic return type fire button, which is closed only when pressed to start rice cooking for the first time, and is in the open state at other times. Also operating temperature _T2
The temperature sensitive switch 11, which is a series circuit consisting of a break type thermal reed switch 11a and a make type thermal reed switch 11b having an operating temperature T ₃ (<T ₂ ), is connected in series with a resistor 18, and the series circuit includes the capacitor 17, Contact 51 of capacitor switch 5
The discharge circuit 1 is connected in parallel to the series circuit of
9. 20 is a discharge detection circuit for detecting the occurrence of discharge in the discharge circuit, which is composed of an SCR 20a, and its cathode terminal is connected to one of the power supply terminals C
Its anode terminal is connected to the connection point A between the fire button 12 and the diode 21 via the micro heater 15, and its gate terminal is connected to the resistor 18.
is connected to the connection point B with the temperature-sensitive switch 11.

The electric rice cooker of the present invention constructed as described above operates as explained in detail below.

FIG. 3a shows the circuit state when the fire button 12 is closed in order to charge the capacitor 17 before pushing down the rear end 7b of the lever 7 to start cooking rice. Since the contact 41 of the rice cooker switch 4 is not yet closed, the contact 51 of the capacitor switch 5, which operates in the opposite direction, is closed, and the diode 21, the fire button 12, the contact 51 of the capacitor switch 5, and the capacitor 17 A capacitor 17 is charged to which a voltage is applied to a charging circuit 16 consisting of a series circuit. At this time, the ambient temperature of the temperature-sensitive switch 11 is lower than _T3 , so the make type thermal reed switch 11b is opened.
Since no voltage is applied between the gate and cathode of the SCR 20a, no current flows. Therefore, no current flows through the micro heater 15 and the bimetal 13 is not deformed. Next, by pushing down the rear end 7b of the lever 7, the rice cooking switch 4 is closed, the contact 51 of the capacitor switch 5 is opened (the state shown by the solid line in FIG. 1), and rice cooking and heating starts [3rd stage]. See Figure b]. As a result, when the ambient temperature rises and reaches the operating temperature T ₃ of the make type thermal reed switch 11b, the thermal reed switch 11b closes as shown in FIG. 3c, and at this time the operating temperature T ₂ (>T ₃ ) The break type thermal reed switch 11a is also closed, but since the contact 51 of the capacitor switch 5 is open, the capacitor 17 does not discharge. Temperature rises and break type thermal lead slot 1
When the operating temperature _T2 of switch 1a is reached, the switch 11a
When the temperature rises further and reaches the operating temperature _T1 of the rice cooking switch 4, the contact 4 of the rice cooking switch 4 opens.
1 is opened and closed, and the contact 51 of the capacitor switch 5 is closed (the state shown by the two-dot chain line in FIG. 1). However, since the break type thermal reed switch 11a is already open at this time as described above, no discharge occurs (see FIG. 3d). When the rice cooker switch 4 is turned off and the non-heating state continues for a while, the temperature drops to the operating temperature _T2 of the break type thermal reed switch 11a. At this time, the switch 11a
The operating temperature will be T ₂ . At this time, the switch 11
Since a is closed, a discharge circuit 19 is formed and the capacitor 17 is discharged. This allows SCR20a
A voltage is applied between the gate and cathode of the micro heater 15 by the resistor 18, and a current flows through the micro heater 15 (see Fig. 3 e), so the bimetal 13 is heated and bent upward, and the operating rod 42 is As the bimetal 13 pushes up as shown by the solid line in the figure, the contact 41 of the rice cooker switch closes.
See figure f]. As a result, heating by the heater 3 is started again. This is heating over a standing fire. When the temperature rises again and reaches T ₁ , contact 41 of rice cooker switch 4
is opened again, so the heating over the flame is completed and the contact 51 of the capacitor switch 5 is closed. When the temperature drops to _T2 due to the end of the heating process, the break type thermal reed switch 11a closes, but since the capacitor 17 is not charged this time, no discharge occurs and the rice cooking switch 4 is closed again due to the action of the bimetal 13. is never closed. Therefore, the overheating will not be started again. It goes without saying that the discharge detection circuit 20 may be a transistor, other thyristor, or the like. Furthermore, the micro heater 15 may of course be installed near the bimetal 13 as shown in FIG. 5, instead of being directly wound around the bimetal 13 as shown in FIGS. 1 and 4. Furthermore, the temperature-sensitive switch 11 may be composed of a bimetal 22, an electrode 23, an insulator 24, etc. as shown in FIG. 6, instead of being composed of the thermal reed switches 11a and 11b as described above. That is, when the ambient temperature of the bimetal 22 rises, the bimetal 22 bends in the direction of the arrow and comes into contact with the electrode 23 at the aforementioned temperature T ₃ (the state shown by the two-dot chain line 22a), and then further contacts the electrode 23 at the temperature T ₂ or higher. (the state shown by the two-dot chain line 22b). Therefore, a temperature-sensitive switch using this bimetal 22 opens at a temperature below _T3 , closes at a temperature between _T3 and _T2 , and closes at a temperature T2 _.
It has the characteristic of opening at the above point. Furthermore, the seventh
The electric circuit diagram shown in FIG.
It goes without saying that the circuit shown in FIG. 7 also falls within the scope of the present invention since it is a completely electrically equivalent circuit expressed as one circuit.

As described above, the electric rice cooker according to the present invention performs timely heating over the heat after cooking the rice and completely drains excess water, so there is no chance of the rice being cooked raw, and the rice temperature remains constant. Since the starch does not deteriorate rapidly, the gelatinization of starch in the rice grains can proceed sufficiently, resulting in delicious rice. Furthermore, a non-heating state is provided for a certain period of time immediately after the rice is heated, and post-heat heating is performed to condense excess water interposed between the rice grains, so that the above-mentioned pre-heating effect is further enhanced. I can do it.

Additional relationships: A charging circuit that is a series circuit of a capacitor, a capacitor switch, a fire button, etc., a discharging circuit consisting of the capacitor switch, a temperature-sensitive switch, a resistor, etc., and a discharge detection circuit that detects discharge of the discharge circuit. Original patent application Patent No. 1281143 (Special Publication No. 1989-
(No. 851 Publication) This is an essential part of the structure of the invention, but the present invention is an invention that makes this point a main part of the indispensable structure of the invention. This invention achieves the same purpose as the original patented invention in that the charging circuit is charged and the discharge of the charged charge is detected to perform heating over a rice cooker. This is an improved method in which the operation is not based on the electrical output of the detection circuit itself as in the original patent application, but is performed by converting the electrical output into thermal expansion of the metal.

[Brief explanation of the drawing]

Fig. 1 is a schematic lower longitudinal sectional view of the electric rice cooker according to the present invention, Figs. 2 and 7 are electric circuit diagrams of the electric rice cooker, and Fig. 3a shows the state when the capacitor is charged by pressing the fire button. Figure 3b shows when the rice cooker switch is closed, Figure 3c shows when the temperature rises and the temperature sensitive switch is closed, and Figure 3d shows when the rice boils and the rice cooker switch is opened. Figure 3e shows when the temperature drops, the temperature sensitive switch closes, and discharge occurs, Figure 3f
Figure 4 shows the circuit state when the rice cooking switch is closed by the bimetal, Figure 4 shows the micro heater wrapped directly around the bimetal, and Figure 5 shows the micro heater placed near the bimetal. FIG. 6, which shows the installed state, is a diagram showing a temperature-sensitive switch using bimetal. 3... Heater, 4... Rice cooking switch, 41...
Rice cooking switch contact, 5... Capacitor switch, 51... Capacitor switch contact, 11...
...Temperature sensitive switch, 11a...Break type thermal reed switch, 11b...Make type thermal reed switch, 12...Fire button, 13...Bimetal, 14...Holding metal fitting, 15...Micro heater, 16... Charging circuit, 17... capacitor,
18...Resistor, 19...Discharge circuit, 20...Discharge detection circuit, 20a...SCR, 21...Diode, 22...Bimetal, 23...Electrode, 24...
…Insulator.

Claims (1)

[Claims] 1. In an electric rice cooker equipped with a rice cooking heater circuit whose energization is controlled by a thermal rice cooking switch, a capacitor, a capacitor switch, a fire button, a diode, etc. are connected in series and in parallel with the rice cooking heater circuit. a connected charging circuit;
a discharge circuit in which a temperature-sensitive switch and a resistor connected in series are branched from an intermediate point between the capacitor and the ignition button in the charging circuit and connected in parallel to the capacitor and the capacitor switch in the charging circuit; , a micro-heater that generates heat based on the output of the discharge detection circuit, and a bimetal that deforms upon receiving the heat of the micro-heater and operates the rice cooking switch to heat the rice cooker. Characteristic electric rice cooker.