JP2987537B2 - Electric cooker and its control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric cooker such as an oven toaster used in ordinary households.

[0002]

2. Description of the Related Art In recent years, a home electric cooker is also equipped with a microcomputer, and accurate temperature control has been performed even under various fluctuation conditions. Although the field is different as a device equipped with a microcomputer, as shown in Japanese Patent Application Laid-Open No. 62-153636, in a floor heating device, a temperature signal value from a temperature sensor is corrected when a power supply voltage fluctuates, and is always set by a user. There is a configuration in which control is performed at a set temperature.

A conventional electric cooker used in ordinary households will be described below with reference to FIGS. As shown in FIG. 6, heaters 3 and 4 are mounted inside a heating chamber 2 provided inside the main body 1, and the heaters 3 and 4 are turned on by a relay or the like for a fixed time set by a timer, so that the heating chamber The material 5 placed inside 2 is cooked by heating. Reference numeral 6 denotes a control unit having functions such as a timer and a relay drive circuit, and reference numeral 7 denotes a timer setting means for setting time.

FIG. 7 is a block diagram of an electric cooker. A timer setting means 7 and a heating power setting means 8 are connected to a control section 6 having a timer and a heating power adjusting function. The circuit 9 is operated to open and close the relay contacts 10 connected to the heaters 3 and 4 to control the power supply to the heaters. The cooking is performed by setting the cooking time by the timer setting means 7, selecting the duty ratio of the heater by the heating power setting means 8 and heating the material 5 inside the heating chamber 2 with a constant heating power for a certain time. It has become.

[0005]

However, such a configuration of the electric cooker has a drawback that when the voltage changes and the power of the heater changes, the cooking is significantly affected.

[0006] Table 1 shows the change of the heater power with respect to the power supply voltage. The heater power of 1000 W at 100 V is reduced to 810 W at 90 V and 121 W at 110 V.
It will rise to 0W.

[0007]

[Table 1]

The set thermal power is 20/32 in terms of the duty ratio.
(20 seconds on, 12 seconds off)
625W at 00V, 506W at 90V, 75 at 110V
6 W, which greatly changes depending on the voltage.

Therefore, even if the cooking time set by the timer has elapsed, the fire has not yet been sufficiently heated,
Sometimes it was over-baked.

An object of the present invention is to solve the above-described problem and to suppress a change in heater power with respect to a change in power supply voltage.

[0011]

In order to achieve the above object, an electric cooker according to the present invention comprises a heater, a relay contact connected in series to the heater, and a cooking chamber or a cooking chamber heated by the heater. A container, a heater power switching means for turning on and off the heater by a relay to change heating power, and a first DC voltage source configured from an AC power supply through a voltage reduction means comprising a rectifier and a zener diode. And a power supply voltage detecting means for detecting a potential difference between the first and second DC voltage sources to detect a power supply voltage. The output of the power supply voltage detecting means The heater power set by the heater power switching means is automatically switched.

Further, the electric cooker of the present invention comprises a heater,
A relay contact connected in series with the heater, a heating chamber or cooking vessel for cooking heated by the heater, heater power switching means for turning on and off the heater by a relay to change heating power, and the relay A timer means for energizing the heater for a fixed time set by a contact, a first DC voltage source constituted from an AC power supply through a voltage reduction means comprising a rectifier and a Zener diode, and a stabilized second A DC voltage source, the first
And a power supply voltage detecting means for detecting a power supply voltage by detecting a potential difference between the power supply voltage and the second DC voltage source. The power supply time of the heater set by the timer means is automatically changed by an output of the power supply voltage detecting means. I did it.

The power supply time for changing the heater power or the power supply voltage for changing the heater power is determined when the relay contact is turned on.

Further, the control device for an electric cooker according to the present invention comprises:
A heater, a relay contact connected in series with the heater,
A heating chamber or cooking vessel for cooking heated by the heater; a first DC voltage source configured from an AC power supply through a voltage reduction means including a rectifier and a zener diode; and a stabilized second DC voltage source And a power supply voltage is detected by detecting a potential difference between the first and second DC voltage sources.

Further, in the control device of the electric cooker according to the present invention, a varistor for correcting the temperature characteristic of the voltage reducing means comprising a zener diode is provided in the potential difference detecting circuit, and the potential difference detecting circuit is constituted by a resistor and a capacitor. The resistor is provided with a semi-fixed resistor for voltage adjustment so that the output voltage of the potential difference detection circuit can be adjusted, and the output voltage of the potential difference detection circuit is connected to an AD converter.

Further, the control device for an electric cooker according to the present invention comprises:
A varistor for correcting the temperature characteristic of the voltage reducing means composed of a Zener diode is provided in the potential difference detection circuit.

Further, the control device for the electric cooker of the present invention comprises:
A varistor for compensating the temperature characteristics of the voltage reduction means consisting of a Zener diode is provided in the potential difference detection circuit, a Schottky barrier diode is connected in anti-parallel to the output terminal of the voltage detection circuit, and connected to the AD converter. Is what you do.

[0018]

According to the present invention, since the heater power is switched by the output of the power supply voltage detecting means in the above-described configuration, the change in the heater power can be suppressed to a low level with respect to the change in the power supply voltage. The characteristics when cooking at the same time are not affected by the change in the power supply voltage.

Further, the setting time of the timer means for determining the energization time of the heater is changed by the output of the power supply voltage detecting means, so that the influence of the change in the heater power on the change in the power supply voltage can be suppressed. Thus, the characteristics of cooking in a short time such as toast are not affected by a change in the power supply voltage.

Further, since the power supply voltage is detected when the relay contact is turned on, it is possible to correct the effect of the power supply voltage drop due to the power supply to the heater.

Further, since a change in the power supply voltage can be taken as a large voltage change as a signal of the detection circuit, a change in the power supply voltage can be detected stably, and the operation stability can be improved.

Further, since the Zener diode is used as the voltage reduction means, the power supply voltage detection means with little change over time in the voltage reduction characteristic and good stability can be constituted.

Further, since the varistor is provided in the potential difference detection circuit, the temperature characteristics of the Zener diode are corrected, and the variation in the detection characteristics is reduced.

Further, since a semi-fixed resistor is connected to the potential difference detecting circuit and means for adjusting the output voltage of the potential difference detecting circuit are provided, the output voltage at 100 V is used as one of the inputs of the AD converter.
/ 2 can be set. Therefore, the range of the power supply voltage to be detected can always be kept constant.

Since the Schottky barrier diode is connected in anti-parallel to the input terminal of the AD converter and the output terminal of the potential difference detection circuit, the output of the potential difference detection circuit exceeds the power supply voltage of the AD converter by a certain voltage or more. As a result, it is possible to prevent the A / D converter from rising and falling, thereby preventing a failure of the AD converter.

[0026]

【Example】

Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 1 is a block diagram of an electric cooker, in which heaters 11 and 12 are attached to a heating chamber of a main body as electric heating means. In other cookers, a cooking container is placed on the heater 11. A relay contact 13 is turned on and off by a relay drive circuit 14.

The first DC power supply 15 is a AC power supply and includes a voltage reducing means 17 comprising a diode 16 and a Zener diode.
It is connected via a resistor 18. Reference numeral 19 denotes a second DC power supply whose voltage is stabilized. The two power supplies are supplied with a voltage difference between the two voltages by the potential difference detection circuit 20, and this voltage gives a change in the power supply voltage. This potential difference detection circuit 20 operates as follows. The capacitor 21 is connected to a second DC voltage V by a resistor 22 and a semi-fixed resistor 23.
2, but is discharged by the value of the first DC voltage V1. The Zener diode 24 is provided to correct the difference between the two voltages, and Vx = V2−V1
+ Vz3 holds. Here, Vx is an output voltage value of the potential difference detection circuit 20 proportional to the power supply voltage. V1 is the voltage value of the first DC power supply 15. V2 is the stabilized voltage value of the second DC power supply 19. Vz3 represents the voltage of the Zener diode 24.

Voltage reducing means 1 composed of a Zener diode
7, the first DC voltage V is simply obtained by dividing the voltage by a resistor.
The change in the power supply voltage is larger than in the case of obtaining 1, and appears in the output voltage Vx of the potential difference detection circuit 20.

Numerals 25 and 26 are inserted in the varistors so as to compensate for the temperature characteristics of the Zener diode 24 used as voltage reducing means. As a result, the output voltage Vx of the potential difference detection circuit 20 also shows a value having almost no temperature characteristic.

The semi-fixed resistor 23 can change the output voltage Vx of the potential difference detection circuit 20 by adjusting this value. Therefore, even if the second DC voltage V2 varies, the output voltage Vx of the potential difference detection circuit 20 can be set to 1/2 of the voltage, and the detection range of the power supply voltage can be always kept constant. The semi-fixed resistor may be provided in the first DC power supply 15 to adjust the first DC voltage V1.

Reference numerals 27 and 28 denote Schottky barrier diodes having a small forward effect voltage Vf, which are connected to the output terminal of the potential difference detecting circuit 20.
When the battery is charged or turned off, the capacitor 2
The voltage remaining at 1 is prevented from exceeding the second DC voltage V2, and the input terminal of the AD converter 29 is protected.

The example of FIG. 1 has a configuration in which the power supply voltage detecting means is applied to the electric cooker at the same time, and the timer setting means 31 and the heating power setting means 32 are connected to the power switching means of the microcomputer 30. Have been. A
The D converter 29 has a function inside the microcomputer 30.

FIG. 2 is a characteristic diagram showing how the detection voltage Vx changes according to the power supply voltage in the present embodiment. When the power supply voltage is 100 V, the detection voltage Vx is set to １ ／ of the second DC voltage V2. , 90 to 110, the detection voltage Vx can be set to change within the range of the second DC voltage V2.

FIG. 3 is a flowchart of a program of the heater power switching means 30 in the embodiment of the present invention. Depending on the voltage range at each step, the relay contacts 13
Of the heaters 11 and 12 is changed from 16/32 to 24/32. Therefore,
As shown in (Table 2), even if the power supply voltage changes and the heater power changes, the relay duty changes and the average power becomes almost constant.

[0036]

[Table 2]

FIG. 4 shows a case where the duty is changed by the power supply voltage (P1) {shown in Table 2} and a case where the duty is changed (P1).
2) The relationship between the average power of 電源 shown in (Table 1) and the power supply voltage is shown, and (P1) is almost constant with respect to the change of the power supply voltage.

As a result, regardless of the power supply voltage, the timer time set by the timer setting means 31 can always produce a fixed result.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a flowchart of a program for changing the heater energizing time in accordance with a change in the power supply voltage. Depending on the voltage range at each step, the relay contacts 13
, Ie, the energization time of the heaters 11 and 12 is increased or decreased by the voltage. Therefore, the influence of the power supply voltage is also eliminated in cooking performed in a short time such as toast.

As shown in the flow charts of FIGS. 3 and 5, when the operation is started in any case, the relay contact 13 is first closed, and then the power supply voltage is checked.
Therefore, there is an effect that the influence of the voltage drop caused by energizing the heater is also removed.

The connection to the heater is not limited to the relay, but a triac, thyristor, or the like may be used. To change the duty ratio, the phase may be changed in addition to the duty.

[0043]

As is apparent from the above description, according to the present invention, power supply voltage detecting means capable of obtaining a detection voltage proportional to the power supply voltage with a simple configuration can be realized, and the output thereof can be reduced by the voltage reducing means. Since the voltage can be increased, the operation stability is high.

Further, since a varistor for correcting the temperature characteristic of the voltage reducing means composed of a Zener diode is provided in the potential difference detection circuit, an output voltage with a small temperature characteristic can be obtained, and the variation in operation can be reduced. Becomes

Further, since the output adjusting means of the potential difference detecting circuit composed of the semi-fixed resistor is provided, the voltage variation of the Zener diode and the second DC power supply is corrected to always obtain a constant power supply voltage detecting characteristic. Will be able to do it.

Further, the electric power of the heater can be switched by the voltage, so that a constant cooking time can be obtained for a constant cooking time, and a cooker with good usability can be realized.

The timer setting time is corrected for a short cooking time such as a toast, so that a constant toast can be obtained even when the voltage changes, and a power supply can be provided when the relay contact is closed. Since the voltage is detected, an excellent practical effect such as the effect of the voltage drop due to the energization of the heater can be eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electric cooker according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram of the electric circuit.

FIG. 3 is a flowchart of a program of a heater power switching unit.

FIG. 4 is a comparison characteristic diagram of the characteristics of the heater power switching means and the conventional characteristics.

FIG. 5 is a flowchart of a program for an electric cooker according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing an example of a conventional electric cooker.

FIG. 7 is a block diagram showing an example of a conventional electric cooker.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Heater 12 Heater 13 Relay contact 15 1st DC power supply 16 Rectifier (diode) 17 Voltage reduction means (Zener diode) 19 2nd DC power supply 20 Power supply voltage detection means (potential difference detection circuit) 30 Heater power switching means (microcomputer) )

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F24C 7/04 301 A47J 37/08 H05B 6/12 304

Claims (7)

(57) [Claims] 1. A heater, a relay contact connected in series with the heater, a heating chamber or a cooking vessel for cooking heated by the heater, and a heating power variable by turning the heater on and off by a relay. A first DC voltage source constituted by a heater power switching means, a first DC voltage source formed from an AC power supply through a voltage reducing means including a rectifier and a Zener diode, and a first and second DC voltage sources; Power supply voltage detecting means for detecting a power supply voltage by detecting a potential difference of the DC voltage source, and automatically changing a heater power set by the heater power switching means by an output of the power supply voltage detecting means. Cooking device. 2. A heater, a relay contact connected in series with the heater, a heating chamber or a cooking vessel for cooking to be heated by the heater, and a heating power variable by turning on and off the heater by a relay. Heater power switching means, timer means for energizing the heater for a predetermined time by the relay contact, and a first DC voltage source constituted by an AC power supply via a voltage reduction means comprising a rectifier and a zener diode And a power supply voltage detecting means for detecting a power supply voltage by detecting a potential difference between the first and second DC voltage sources,
An electric cooker in which the power supply time of the heater set by the timer means is automatically changed by the output of the power supply voltage detecting means. 3. A heater, a relay contact connected in series to the heater, a heating chamber or a cooking vessel for cooking heated by the heater, and a heating power variable by turning on and off the heater by a relay. A first direct current voltage source constituted by heater power switching means, timer means for energizing the heater by the relay contact for a set time, and voltage reduction means comprising a rectifier and a zener diode from an AC power supply And a power supply voltage detecting means for detecting a power supply voltage by detecting a potential difference between the first and second DC voltage sources,
An electric cooker in which the power supply time of the heater or the heater power set by the timer means is automatically changed by the output of the power supply voltage detection means, and the power supply voltage is detected when the relay contact is turned on. 4. A heater, a relay contact connected in series with the heater, a cooking heating chamber or a cooking vessel heated by the heater, and a voltage reducing means comprising a rectifier and a zener diode from an AC power supply. An electric cooker having a configured first DC voltage source and a stabilized second DC voltage source, configured to detect a potential difference between the first and second DC voltage sources and detect a power supply voltage. Control device. 5. The control device for an electric cooker according to claim 4, wherein a varistor for correcting the temperature characteristics of the voltage reducing means comprising a Zener diode is provided in the potential difference detection circuit. 6. A varistor for correcting a temperature characteristic of a voltage reducing means comprising a Zener diode is provided in a potential difference detecting circuit, and the potential difference detecting circuit comprises a resistor and a capacitor. 5. The control device for an electric cooker according to claim 4, wherein a fixed resistor is provided so that the output voltage of the potential difference detection circuit can be adjusted, and the output voltage of the potential difference detection circuit is connected to the AD converter. 7. An A / D converter comprising: a varistor for correcting a temperature characteristic of a voltage reducing means comprising a Zener diode provided in a potential difference detection circuit; a Schottky barrier diode connected in antiparallel to an output terminal of the voltage detection circuit; 5. The control device for an electric cooker according to claim 4, wherein the control device is connected to the electric cooker.