JPH0443151Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) The present invention relates to a rice cooker that executes a rice cooking process by setting dry-up detection conditions corresponding to the power supply voltage.

(Prior Art) A conventional rice cooker of this type includes a heater drive means for energizing a heater for heating the pot, a temperature detection means for detecting the temperature of the pot, and a dry-up function based on the temperature detected by the temperature detection means. and a control means for controlling on/off of the heater, and controlling the heater based on temperature detection by the temperature detection means, dry-up detection by the dry-up detection means, etc. The rice cooking process is executed by driving the rice cooker by a means. A specific example of this will be explained with reference to Fig. 6, which shows the case of brown rice or takikomi-cooking.First, the simmering process (not shown) is executed by turning the heater on and off at 100% high output H, and then the rice is cooked. Move to the process. In this rice cooking process, as shown in the temperature curve a, the heater is normally turned on at a high output H of 100V, and after the boiling state, the temperature detected by the temperature detection means that detects the temperature of the pot reaches a predetermined temperature, for example, 115℃. P is detected as a dry-up state by the dry-up detection means, and the heater is turned off to end the rice cooking process.

(Problem that the invention aims to solve) Conventionally, this type of rice cooker has a structure in which the temperature of the pot is detected by a thermistor that is in contact with the bottom of the pot. When the power supply voltage fluctuates, the balance of the heat conduction paths ht ₁ , ht ₂ , ht ₃ shown in Fig. 4 changes, which changes the detection state of the pot temperature by the thermistor, and the rice cooking capacity increases. Even if the rice cooking conditions, such as the amount of water, are the same, the state of cooked rice varies. For example, when the power supply voltage reaches a high voltage of 105V, as shown in temperature curve b, before the dry-up state,
When the detected temperature tk reached 115°C, the heater was turned off and the cooking process was completed, resulting in a problem where the rice became undercooked. On the other hand, when the power supply voltage becomes a low voltage of 95V, the detected temperature tk reaches 115℃ with overshoot as shown by temperature curve c.
There was a problem that the rice was burnt because the heater was turned off and the cooking process was completed. In order to avoid problems such as undercooked or burnt rice caused by fluctuations in the power supply voltage, capacity is detected based on the time it takes for the detected temperature tk to change from 70℃ to 80℃, as is normally done when cooking white rice. A similar problem has also occurred in rice cookers that detect dry-up based on the range of temperature rise from the reference temperature in the boiling state.

Therefore, an object of the present invention is to provide a rice cooker that can effectively detect a dry-up state even when fluctuations in power supply voltage occur.

[Structure of the invention] (Means for solving the problems) The present invention includes a driving means 19 for the heater 5, a temperature detecting means 10 for detecting the temperature of the pot 3, a power supply voltage detecting means 12, a control means 13, and the like. The control means 13 sets the dry-up detection condition td based on the power supply voltage ek detected by the power supply voltage detection means 12, and the temperature tk detected by the temperature detection means 10.
This rice cooker is controlled to turn off the heater 5 and end the rice cooking process when the dry-up detection condition td is reached.

(Function) The present invention is controlled so that when the temperature tk detected by the temperature detection means 10 reaches the dry-up detection condition td set based on the power supply voltage ek detected by the power supply voltage detection means 12, the heater 5 is turned off. Ru.

(Example) Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

Fig. 4 shows the schematic structure of the rice cooker, in which 1 is the main body of the rice cooker, 2 is the lid, 3 is a pot serving as a container, and 4 is the bottom of the pot 3 when the pot 3 is accommodated in the main body 1. A temperature sensor configured to be in contact with it; 5 a heater as a heating means disposed below the pot 3; 6 a food to be cooked; rice 7 and water 8;
It consists of.

FIG. 1 is a block diagram showing the electrical configuration.
In the figure, 9 is an A/D converter which together with the temperature sensor 4 constitutes a temperature detecting means 10, which detects the temperature of the pot 3 by means of the temperature detecting means 10, and adjusts the temperature according to the detected temperature tk. Outputs a detection signal.
Reference numeral 11 denotes a power supply voltage detection circuit which together with the A/D converter 9 constitutes a power supply voltage detection means 12, which detects the power supply voltage by the power supply voltage detection means 12;
A voltage detection signal corresponding to the detected power supply voltage ek is output. 13 is a control means consisting of a microcomputer, which, as is well known, controls the A/D converter 9, the CPU 14, the timer circuit 15, and the memory 1.
6, an input circuit 17, an output circuit 18, etc. This control means 13 controls the drive of the heater 5 according to the control program it owns, and detects the detected temperature tk from the temperature detection means 10.
Based on this, detection of a dry-up state, etc., which will be described later, is performed. Reference numeral 19 denotes a driving means for the heater 5, which turns on and off the heater 5 based on a heater on signal and a heater off signal given from the control means 13.

FIG. 2 shows a circuit diagram, and as shown in the figure, the output terminal of the power supply voltage e is connected to the heater 5 and the drive means 1.
The normally open contact 20a of the relay 20 constituting the heater 5 and the normally open contact 20a of the relay 9 are connected in series.
A first voltage dividing resistor 1 with a large resistance value, which constitutes the power supply voltage detection circuit 11, is connected via a diode 21.
1a and a second voltage dividing resistor 11b having a small resistance value are connected in parallel, and a capacitor 22 is connected in parallel to this power supply voltage detection circuit 11. On the other hand, a DC power supply circuit 23 is connected to the power supply voltage e, and lines L ₁ and L ₂ of this DC power supply circuit 23
In between are a series circuit of a temperature sensor 4 such as a thermistor and a resistor 24, a control means 13 consisting of a microcomputer, and an excitation coil 20 of the relay 20.
b and a series circuit of transistor 25 are connected in parallel. The input/output terminals I ₁ and I ₂ of the control means 13 are connected to the connection point between the temperature sensor 4 and the resistor 24 and the first and second voltage dividing resistors 11a and 1.
1b are connected to each other, and the control means 13
The base of the transistor 25 is connected to the output terminal Q of the transistor 25 via a resistor 26, and the base and the resistor 2
A resistor 27 is connected between the connection point 6 and the line _L2 of the DC power supply circuit 23. Note that this circuit diagram omits the heat-retaining heater or an output adjustment circuit provided as necessary.

Next, the control of each stroke will be explained with reference to FIGS. 3 and 5. When the rice cooking start switch (not shown) is turned on, the control means 13 sets the output of the heater 5 to high output (100% output), and also connects the output terminal Q of the control means 13 to the base of the transistor 25 of the drive means 19. When a current is supplied to the transistor 25, the transistor 25 is turned on and the relay 20 is activated. As a result, as shown in step _S1 , the heater 5 is turned on to carry out a steaming process (not shown), and when the steaming process is completed, the process shifts to the rice cooking process. In this rice cooking process, the output of the heater 5 is maintained at high output H, and the on state is maintained.
is heated and the contents inside pot 3 (rice 7 and water 8)
is heated. Then, as shown in step _S2 , it is determined whether the temperature tk detected by the temperature detecting means 10 equipped with the temperature sensor 4 has reached 100°C or more, and if tk≧100 (°C) has been reached, step As shown by _S3 , the first and second voltage dividing resistors 11a and 11b
The divided voltage at the voltage dividing point is supplied to the input terminal _I2 of the control means 13, and a voltage detection signal corresponding to the power supply voltage e is outputted via the A/D converter 9. Then, it is determined whether the detected power supply voltage ek has reached 105V or more, and as shown in temperature curve B in Figure 3.
If ek≧105V has been reached, set the dry-up detection condition TD to 120℃ as shown in step _S4 ,
As shown in step _S5 , it is determined whether the temperature tk detected by the temperature detection means 10 has reached the set dry-up detection condition td (120°C), and tk
When the temperature reaches ≧120 (° C.), the point P is detected as a dry-up state. Next, as shown in step _S6 , the heater 5 is turned off via the relay 20 to complete the rice cooking process. On the other hand, if the detected power supply voltage ek has not reached 105V or higher in step _S3 , the routine moves to a routine that follows "NO", and as shown in step _S7 , it is determined whether or not the detected power supply voltage ek is smaller than 95V. Ru. And the temperature curve C in Figure 3
If ek < 95 (V), the routine moves to "YES" and the dry-up detection condition td is set to 110°C as shown in step _S8 , and then as shown in steps _S5 and _S6 . When the detected temperature tk reaches 110° C. or more, the time point P is considered to be a dry-up state and the heater 5 is turned off. In addition, if the detected power supply voltage ek is 95V or more as shown in the temperature curve _A in _FIG .
Set td to 115℃ and then step S ₅ ,
As shown in _S6 , when the detected temperature tk reaches 115° C. or higher, the heater 5 is turned off at that point P as a dry-up embodiment.

In this manner, in the above state, the detected temperature tk of the temperature detection means 10 is set to a predetermined temperature of 90°C or higher, for example.
When the temperature reaches 100℃ or more, the detected power supply voltage ek
is detected, and the dry-up detection condition td is set based on this detection result, and if the detected power supply voltage ek is above normal, the dry-up detection condition td is set high, and if the detected power supply voltage ek is below normal, dry-up is detected. Since the condition td is configured to be set low, when the detected power supply voltage ek is 105V, conventionally the heater 5 is turned off before the dry-up state as shown in temperature curve b, resulting in an undercooked state.
In this embodiment, the heater 5 is turned off in a dry-up state as shown by temperature curve B in FIG. Furthermore, when the detected power supply voltage ek is 95V, conventionally the heater 5 is turned off and burnt in the state of overshoot as shown in the temperature curve c, but in this embodiment, as shown in the temperature curve C of FIG. Since the heater 5 is turned off in a dry-up state without overshooting, it is possible to cook rice well without undercooking or burning even if the power supply voltage e fluctuates.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the scope of the gist of the present invention. For example, although the above embodiment has been explained using brown rice and cooked rice as examples, the present invention can be applied to white rice, rice cooked with rice, rice porridge cooked, etc. For example, in the case of a rice cooker that detects the rice cooking capacity and sets the dry-up detection conditions according to the detected capacity, the dry-up detection conditions are set by calculating the corrected temperature α according to the detected power supply voltage. You can. Moreover, although each function of the control means is obtained by the control means comprising a microcomputer, they may be obtained by individual electronic circuits.
Further, the power supply voltage detection means may be an appropriate circuit, and the power supply voltage may be detected a plurality of times to collect data.

[Effects of the invention] The present invention uses the power supply voltage detection means to set the dry-up detection conditions according to the detected power supply voltage, so even when there are fluctuations in the power supply voltage, dry-up conditions can be detected well, and undercooked or burnt food can be detected. It is possible to provide a rice cooker that can provide good cooked rice without any problems.

[Brief explanation of drawings]

1 to 5 show an embodiment of the present invention,
Fig. 1 is a block diagram showing the electrical configuration, Fig. 2 is a circuit diagram, Fig. 3 is a graph showing detected temperature changes, Fig. 4 is a sectional view showing the schematic structure of the rice cooker, and Fig. 5 is a flowchart. 6 are graphs showing conventional detected temperature changes. 3... Pot, 5... Heater, 10... Temperature detection means, 12... Power supply voltage detection means, 13... Control means, 19... Heater driving means.

Claims (1)

[Scope of utility model registration request] A dry-up detection condition is set based on a heater driving means, a temperature detection means for detecting the temperature of the pot, a power supply voltage detection means, and a detected power supply voltage of the power supply voltage detection means, and the temperature detected by the temperature detection means is set. A rice cooker comprising: a control means configured to turn off the heater when the set dry-up detection condition is met.