JPS6255853B2 - - 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 shall apply hereinafter) that automatically performs additional cooking and heating at fixed time intervals after a predetermined time has elapsed from the end of rice cooking. be.

In order to cook rice deliciously, it is necessary to remove excess water that clings to the rice after it has finished cooking, and to remove the α of the starch in the rice grains even after the rice has finished cooking.
It is important to encourage this process and allow it to progress to the inside. The process of gelatinization of starch in rice grains stops when the temperature of the rice drops below a predetermined temperature, and once it stops, it is no longer carried out.

For this reason, conventionally, a motor cam timer is used to perform additional cooking and heating at fixed time intervals after a predetermined period of time has passed after the rice has finished cooking, to remove the moisture that has adhered to the rice and to raise the temperature inside the rice cooker to a predetermined temperature or higher. By maintaining the rice, the gelatinization of starch progresses to the core of the rice grain, resulting in fluffier and more delicious rice.

However, with conventional electric rice cookers that use the motor cam timer mentioned above to perform additional heating, there was a problem that the power frequency was different between the Kanto region and the Kansai region, resulting in a difference in motor rotational speed and a change in the set time. . For this reason, as a business, it is necessary to display the timing of additional heating and the heating time for each of the Kanto and Kansai regions.On the other hand, for consumers, if they move to an area with a different frequency, etc.
I had to be very careful when cooking rice.

In addition, if the motor cam timer stops operating midway due to a power outage or unplugging the outlet plug, the motor cam timer will stop operating after the above midway point when the power is turned on to keep warm. There was a problem in that the system started to operate and additional heating was performed in a timely manner.

Therefore, the present invention improves the conventional electric rice cooker in view of the above-mentioned drawbacks, uses a CR circuit, starts discharging the capacitor of the CR circuit at the same time as rice cooking ends, and T ₀ from the start of discharging. To provide an electric rice cooker which automatically performs additional cooking and heating by energizing a rice cooking heater at intervals of a fixed time t after a lapse of time, thereby cooking more fluffy and delicious rice.

EMBODIMENT OF THE INVENTION Below, the electric rice cooker with additional cooking which concerns on this invention (henceforth this invention rice cooker) is demonstrated based on the drawing which shows the Example.

Figure 1 shows the main circuit of the rice cooker of the present invention, in which a non-returnable heat-responsive rice cooking switch 1 that closes when rice cooking starts and opens when the rice boils, and a rice cooking heater 2 that heats the rice are connected in series. The connected rice cooking circuit A is connected between the AC100V power supply. B is a relay circuit in which _a switching element SW such as a transistor or a thyristor is connected in series with _a relay
connected between power supplies. A common terminal K of the double-throw relay contact Xc of the relay X is connected to an intermediate point P between the rice cooking switch 1 and the rice cooking heater 2 in the rice cooking circuit A, and the relay contact Xc
A resistor R ₀ is connected to one switching terminal L of the switch. The other switching terminal M of the relay contact Xc is connected to one side of the 100V AC power supply, and when the relay contact Xc is switched to the switching terminal M side, the rice cooking heater 2
It is designed to allow current to flow through it. In the figure, C is the additional cooking device in which capacitor C ₂ and resistor R ₂ are connected in parallel to control the additional cooking time.
It is a CR circuit and is connected in parallel to the rice cooking heater 2 via a rectifying element D ₂ , a resistor R ₀ , a switching terminal L of a relay contact Xc, and a common terminal K. D is a CR circuit for storing rice cooking, which is composed of a capacitor C ₃ and a resistor R ₃ connected in parallel, and includes a rectifier D ₃ and a rectifier.
D ₂ , resistor R ₀ , is connected in parallel to the rice cooking heater 2 via the switching terminal L of the relay contact Xc and the common terminal K, and has the function of preventing additional heating from being performed when heating rice as described later. It is a circuit. ZD ₁
is connected in parallel to CR circuit C for additional cooking, and for additional cooking
This is a Zener diode for preventing the voltage applied to the CR circuit C from exceeding a predetermined voltage. The series circuit consisting of the resistor _R11 and the resistor _R12 is a constant voltage voltage dividing circuit connected to the AC power supply via the resistor _R1 and the rectifying element _D1 , and is connected to the comparator described later.
It outputs the reference voltage V ₁ to COM ₁ . resistance
The series circuit consisting of R ₂₁ and resistor R ₂₂ is connected to the resistor
Connected in parallel to a constant voltage divider circuit consisting of R ₁₁ and R ₁₂ ,
It outputs a reference voltage _V2 to a comparator _COM2 , which will be described later. A series circuit consisting of a resistor R ₃₁ and a resistor R ₃₂ is also connected in parallel to the constant voltage dividing circuit consisting of the resistors R ₁₁ and R ₁₂ , and outputs a reference voltage V ₃ to a comparator COM ₃ , which will be described later. . The voltage applied to each constant voltage circuit is a Zener diode ZD ₂
A parallel circuit consisting of a capacitor C1 and a capacitor _C1 maintains a predetermined voltage. E is each output Vm ₁ from comparator COM ₁ , comparator COM ₂ and comparator COM ₃ ,
It is an AND circuit to which Vm ₂ and Vm ₃ are input.
The switching element SW is opened and closed by a signal output from the AND circuit E. Comparator COM _{1
The + side} input terminal _of
A reference voltage V ₁ ) is inputted thereto, and a voltage Vc ₂ across the capacitor C ₂ of the CR circuit for additional heating is inputted to its one side input terminal. The voltage Vc 2 across the capacitor C ₂ is input to the + input terminal of the comparator COM ₂ , and the voltage Vc ₂ across the capacitor C ₂ is input to the − input terminal of the comparator COM ₂ . ₂ voltage (reference voltage V ₂ of comparator COM ₂ ) is input. The above-mentioned CR for rice cooking memory is connected to the + side input terminal of comparator COM ₃ .
The voltage Vc ₃ across the capacitor C ₃ in circuit D is input to its negative input terminal, and the voltage at the midpoint F ₃ of the constant voltage divider circuit consisting of the resistors R ₃₁ and R ₃₂ (comparator
The reference voltage V ₃ ) of COM ₃ is input. Each comparator COM ₁ , COM ₂ , COM ₃ compares the voltage input to the respective + and - side input terminals, and the voltage input to the + side input terminal is higher than the voltage input to the - side input terminal. This circuit outputs a voltage signal in a high state when the voltage is higher than the voltage, and outputs a voltage signal in a low state when it is lower than the voltage. _R4 is a main heater for keeping warm, and is connected to the rice cooking switch 1 via a thermal reed switch 3 for controlling the keeping temperature. _R5 is an auxiliary heater for keeping warm, and _R6 is a lid heater.

Next, the operation of the rice cooker of the present invention will be explained.

When the rice cooking switch 1 is turned on and rice cooking is started by the rice cooking heater 2, the rice temperature T rises as shown in FIG. 2a. Since the relay contact Xc at the start of rice cooking is switched to the switching terminal L side as shown in the figure, a predetermined voltage is applied to the capacitor _C2 of the CR circuit C for additional cooking via the resistor _R0 rectifier _D2 . As shown in Figure 2b, the capacitor
C ₂ begins to charge. At the same time, a voltage of the same magnitude as the voltage applied to the capacitor _C2 is applied to the capacitor _C3 in the rice cooking memory CR circuit D via the rectifying element _D3 , as shown in Fig. 2b. It will start to charge. In the illustrated embodiment, the capacitances of capacitor C ₂ and capacitor C ₃ are the same. At the beginning of rice cooking, the capacitors C ₂ and C ₃
Since the charging voltages Vc ₂ and Vc ₃ are still low, the comparator
The output Vm ₁ of COM ₁ is in high state, the output Vm ₂ of comparator COM ₂ is in low state, the output Vm ₃ of comparator COM ₃ is in
It is in a low state. Comparator COM ₁ , COM ₂ , COM ₃
The relationship between the reference voltages V ₁ , V ₂ , and V ₃ is shown in Figure 2 b.
As shown, the relationship is V ₃ > V ₁ > V ₂ . First, when the charging voltages Vc _{2 and} Vc _{3 of the capacitors C 2 and C 3 reach} the reference voltage V ₂ of the comparator COM ₂ , the output Vm ₂ of the comparator COM ₂ changes from the Low state as shown in Fig. 2g. Shifts to High state. However, since the output Vm ₃ of the comparator COM ₃ is still in the Low state, no signal is output from the AND circuit E. Furthermore, charging voltage
When Vc ₂ and Vc ₃ rise and reach the reference voltage V ₁ of the comparator COM ₁ , the output Vm ₁ of the comparator COM ₁ changes from the High state to the Low state as shown in FIG. 2f. When the charging voltages Vc ₂ and Vc ₃ further increase and reach the reference voltage V ₃ of the comparator COM ₃ , the output Vm ₃ of the comparator COM ₃ changes from the Low state to the High state as shown in FIG. 2e.
However, since the output Vm ₁ of the comparator COM ₁ is in the Low state, no signal is output from the AND circuit E. After the charging voltages Vc ₂ and Vc ₃ further increase and reach the breakdown voltage of the Zener diode ZD ₁ , the voltages Vc ₂ and Vc ₃ across the capacitors C ₂ and C ₃ are maintained at the breakdown voltage. When the rice cooking is finished, the rice cooking switch 1 is opened (see FIG. 2 c), and the heating of the rice by the rice cooking heater 2 is completed (see FIG. 2 d). As a result, no voltage is applied to the relay contact Xc, the capacitors C ₂ and C ₃ begin to discharge, and the voltages across them Vc ₂ and Vc ₃ begin to fall as shown in FIG. 2b. In this case, since the resistance R ₂ is smaller than the resistance R ₃ , the discharge rate of the capacitor C ₂ is faster than the discharge rate of the capacitor C ₃ as shown in FIG. 2b. After a predetermined time T ₀ has passed since rice cooking switch 1 was turned off, comparator COM ₁
When the voltage Vc ₂ of the capacitor C ₂ falls to the reference voltage V ₁ of , the output Vm ₁ of the comparator COM ₁ changes from the Low state to the High state. Therefore, for AND circuit E
Since only the voltage in the High state is input, a signal is output from the AND circuit E to the switching element SW, and the switching element SW becomes conductive. As a result, relay X operates, and relay contact Xc is switched to the switching terminal M side. Therefore, current begins to flow through the rice cooking heater 2. In other words, additional heating starts [see Figure 2 d]. Furthermore, when time T ₀ +t has elapsed after the rice cooking switch 1 is turned off, the voltage Vc ₂ across the capacitor C ₂ decreases and the comparator
The reference voltage V ₂ of COM ₂ is reached and the output of comparator COM ₂
Vm ₂ changes from high state to low state. accordingly
The signal is no longer output from the AND circuit E, the relay contact Xc is switched to the switching terminal L side, and the additional heating for the time interval t is completed. This additional heating removes excess moisture from the rice,
Alphatization progresses. On the other hand, the voltage across capacitor C ₃
Vc ₃ slowly falls and becomes the reference voltage of comparator COM ₃ .
When V ₃ is reached, the output Vm ₃ of the comparator COM ₃ changes from the High state to the Low state. From then on, the heat retention state continues. And in the warm state, capacitor C ₂ ,
There is not enough voltage applied to C ₃ to fully charge them. As is clear from the above, the rice cooking memory CR circuit 2 is used to prevent additional cooking during rice cooking.
The outputs Vm ₁ and Vm ₂ of comparators COM ₁ and COM ₂ are both
Even in the High state, the output Vm ₃ of comparator COM ₃ is
In order to set the state to Low and to perform additional heating after the rice is heated, the comparator is turned off after the rice is cooked.
When the outputs Vm ₁ and Vm ₂ of COM ₁ and COM ₂ both become High, the output Vm ₃ of comparator COM ₃ also becomes High.
This is a circuit that is designed to be in the following state. Capacitor C ₂ and resistor
R ₂ , capacitor C ₃ , resistor R ₃ , reference voltage V ₁ , V ₂ ,
The size of V ₃ is determined appropriately. Also, if such effects can be achieved, CR for rice cooking memory
Circuit D may be connected to switching terminal L via rectifying element _D3 .

As mentioned above, the rice cooker of the present invention has a CR for additional cooking.
Using a circuit, after T ₀ hours have passed after the end of rice cooking,
Since additional heating is automatically performed for t time intervals, the set times T ₀ and t are constant in both the Kanto and Kansai regions, where the power supply frequencies are different. Therefore, there is no need to display the set value of the timer for additional cooking separately for both regions. Also, if the electricity is stopped during the heating process due to a power outage, etc., the capacitor will discharge through the resistor, so even if the electricity is turned on to keep it warm, it will no longer perform the heating process. No,
It only keeps warm and operates normally.
It won't burn the rice or damage the main unit. Furthermore, the rice cooker of the present invention controls additional heating by an electric circuit, and the control section is easy to configure and assemble, and does not require a large space. It also has various advantages, such as being able to be manufactured at low cost. Furthermore, it can be used to store rice cooking without using a thermostat etc.
Since the CR circuit prevents additional heating during cooking, there is no need to install a thermostat or other equipment to the rice cooker, and its operation is reliable.

[Brief explanation of the drawing]

The drawings are all drawings showing an embodiment of the rice cooker of the present invention, and FIG. 1 is a main circuit diagram of the rice cooker of the present invention, and FIGS. 2a to 2h are diagrams showing each part of the rice cooker of the present invention. Figure 2a is a graph showing changes over time (horizontal axis) in opening/closing, output status, etc.
(vertical axis) graph, Figure 2b shows capacitors C ₂ and C ₃
Figure _2c is a graph of the ON and OFF states of the rice cooker switch (vertical axis), and Figure 2d is a graph of _the rice cooking heater heating (ON) and non-heating (ON). OFF) state (vertical axis), Fig. 2 e is a graph of the output Vm ₃ (vertical axis) of the comparator COM ₃ , the second
Figure f is a graph of the output Vm ₁ (vertical axis) of comparator COM ₁ , and Figure 2 g is a graph of the output Vm ₂ (vertical axis) of comparator COM ₂ .
The graph of Fig. 2h is the output Vm ₃ of the comparator COM ₃ .
(vertical axis). 1...Rice cooking switch, 2...Rice cooking heater, A...Rice cooking circuit, B...Relay circuit, C...CR circuit for additional cooking,
D...Rice cooking memory circuit, SW...Switching element, X
...Relay, Xc...Relay contact, K...Common terminal, L
…One switching terminal, C ₂ , C ₃ … Capacitor, R ₂ ,
R ₃ ...Resistance, COM ₁ , COM ₂ , COM ₃ ...Comparator,
D ₁ , D ₂ , D ₃ ... Rectifying element.

Claims (1)

[Claims] 1. A relay circuit formed by connecting a switching element and a relay in series is connected in parallel to a rice cooking circuit formed by connecting a rice cooking heater and a rice cooking switch in series, and the common terminal of the double-throw relay contact of the relay is connected to the rice cooking circuit formed by connecting a rice cooking heater and a rice cooking switch in series. A CR circuit for additional cooking is connected to the intermediate point between the switch and the rice heater, and a capacitor and a resistor are connected in parallel to control additional cooking time.The capacitor and resistor are connected in parallel to prevent additional heating during cooking. A CR circuit for storing rice cooking is connected in parallel to the rice cooking heater through one switching terminal of the double-throw relay contact and a rectifying element, and T from the start of discharging of both capacitors by opening the rice cooking switch An electric rice cooker with additional cooking, characterized in that after ₀ hours, the switching element is made conductive for a fixed time interval t, thereby switching the relay contact and allowing the rice heater to perform additional cooking after rice cooking.