JPS62138081A - Controller for number of revolution of electric cooker - Google Patents

Abstract

PURPOSE:To extend the working range of the number of revolution by determining the trigger phase of a thyristor by an output from an integrated circuit connected to an anode for the thyristor. CONSTITUTION:An output from a full-wave rectifier 10 connected at both ends of a power supply is fed to a commutator motor 11 through a thyristor 12. An integrated circuit 13 is connected to an anode for the thyristor 12. A voltage detecting circuit 14 is connected to the integrated circuit 13. A signal from the voltage detecting circuit 14 is transmitted over a gate drive circuit 17 through a delay circuit 15. The delay circuit 15 is controlled by a rheostat 16. The delay circuit 15 is controlled by the rheostat 16, thus changing the trigger phase of the thyristor.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an electric cooking machine such as a food processor that cuts vegetables, fruits, etc. by driving a cutter using a commutator motor or the like.

BACKGROUND OF THE INVENTION Conventional electric cooking machines of this type generally have an electric circuit configuration as shown in FIG.

In FIG. 4, the commutator motor 1 is changing the rotation speed applied to the phase side by the triac 2.

A diac 6 is connected to the gate of the triac 2, and a capacitor 6 is charged by a variable resistor 3 and a resistor 4. When a predetermined voltage is reached, the diac 6 becomes conductive, triggering the triac 2, and energizing the commutator motor. The rotation rate was changed by the variable resistor 3 as described above, and the rotation speed was changed.

Problems to be Solved by the Invention However, this configuration has a drawback in that when a load is applied to the electric motor during cooking, the rotational speed drops significantly. This phenomenon is particularly noticeable when the thyristor's current conductivity is reduced and the rotation speed is low, and the motor is very likely to lock up at low rotation speeds. When the electric motor locks, the current increases abnormally and the windings of the electric motor are burnt out.

The present invention has been made in consideration of the above-mentioned conventional problems, and an object of the present invention is to provide an electric cooking machine in which the electric motor does not lock even when rotating at low speeds and can be used over a wide range of rotational speeds.

Means for Solving the Problems In order to solve the above problems, the technical means of the present invention includes an integrating circuit connected to the anode of the thyristor, a voltage detection circuit connected to the integrating circuit, and a variable delay time. A delay circuit and a thyristor gate drive circuit are provided, and the delay circuit changes the thyristor trigger phase determined by the integration circuit and voltage detection circuit, thereby changing the rotational speed of the motor.

For production The effect of this technical means is as follows.

In other words, the anode voltage of the thyristor is the sum of the power supply voltage and the back electromotive voltage, and this voltage is integrated and the trigger phase of the thyristor is determined by the output of the voltage detection circuit, so when a load is applied and the back electromotive voltage decreases, The output voltage of the integrating circuit increases, the trigger phase advances, and the thyristor conduction rate increases. Therefore, the delay timer circuit changes the phase determined by the voltage detection circuit, resulting in a structure that is difficult to lock even when the rotational speed is low. In other words, it is possible to obtain a rotation speed i+J' variable control circuit that can be used in a wide range of loads.

Example Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 10 is a full-wave rectifier connected to both ends of the power supply, 11 is a commutator motor driven by direct current obtained from the full-wave rectifier 1Q, and 12 is a thyristor provided in the current-carrying circuit of the motor 11. .

An integration circuit 13 is connected to the anode of the thyristor 12, and a voltage detection circuit 14 is connected to the integration circuit 13. The signal from the voltage detection circuit 14 is configured to control a delay circuit 16, and the delay circuit 16 controls the thyristor 12.
A gate drive circuit 17 connected to the gate of the gate is controlled. Further, the delay circuit 15 is connected to a variable resistor 16.
It is now controlled by.

■s and vR in the figure represent the power supply voltage and back electromotive voltage, respectively. The anode voltage of Cyrisk is ■S″″′vR
O Figure 2 shows the output voltage of the integrating circuit 13 and the voltage detection circuit 14.
The relationship between the trigger drive phase and the trigger drive phase determined by is shown. In FIG. 2, the output of the integrating circuit 13 under normal no-load conditions is shown by a curve A. If there is a load here, the output voltage of the integrating circuit 13 changes from A to A, and the trigger phase advances by Δt1 and the energization rate increases. Also,
Since the delay circuit 16 can be controlled by the variable resistor 16 to shift the phase by t, the energization rate changes as shown in FIG. 2, and the rotation speed can be controlled from high speed to low speed rotation.

FIG. 3 shows a specific circuit of one embodiment of the present invention.

As shown, the integrating circuit 13 includes a resistor 18, a diode 19, and a capacitor 20. The voltage detection circuit 14 is composed of a voltage comparator 21.

The delay circuit 16 includes resistors 23 and 24 that generate a reference voltage, a voltage comparator 25, and a variable resistor 1 that constitutes a CR charging circuit.
θ and a capacitor 22. 26 is a transistor forming a gate drive circuit.

Note that the variable resistor 16 placed in the delay circuit 16 may be placed in a reference circuit and replaced with resistors 23, 24, etc.

Effects of the Invention As is clear from the explanation of the embodiments described above, the present invention detects the back electromotive voltage and advances the trigger phase of the thyristor when a high load is applied to increase the energization rate, so that it does not lock even at low speed rotation. 〈〈Because the range of rotational speed can be expanded, the range of cooking applications is expanded, and its practical value is great.

[Brief explanation of drawings]

Figure 1 is a block diagram showing one embodiment of the present invention, Figure 2a
, b are waveform diagrams showing the operation, FIG. 3 is a circuit diagram showing an embodiment of the present invention, and FIG. 4 is a circuit diagram showing a conventional example. 11... Commutator motor, 12... Thyristor, 13... Integrating circuit, 14... Voltage detection circuit, 16... Delay circuit, 16・・・・・・
・Variable resistor, 1. River... Gate drive circuit. Mi; 寥 e:! ! Fig. 2 f r--1111--Fig. 4

Claims (1)

[Claims] It has a motor, a thyristor, an integration circuit connected to the anode of the thyristor, a voltage detection circuit connected to the integration circuit, a delay circuit that can vary the delay time, and a gate drive circuit. A rotation speed control device for an electric cooking machine, wherein the rotation speed of the electric motor is changed by changing the determined trigger phase of the thyristor using a delay circuit.