JPS644318Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a control device for a clutch motor that reduces power consumption and vibration noise during no-load operation of the electric motor, and provides a highly practical device.

Generally, industrial sewing machines perform frequent inching operations, so the clutch motor that drives the sewing machine must keep the flywheel rotating even when the sewing machine is not driving.
The electric motor is running without load.

The reality of sewing work is that 70% of the time the sewing machine is running without load compared to the time it is running.
At that time, in addition to the power required to rotate the flywheel, a lot of power is wasted, such as the excitation current of the motor.

In order to save this wasted power, the voltage applied to the motor is lowered during no-load operation to supply the minimum amount of power necessary to rotate the flywheel, and when the sewing machine is running, the motor is fully charged. An energy-saving clutch motor that applies voltage has been developed.

This invention uses an energy-saving clutch motor to detect whether the sewing machine is running or no-load operation, and applies full voltage to the motor when the sewing machine is running, and applies full voltage to the motor when the sewing machine is running with no load. This invention relates to a control device that has the function of applying the minimum voltage required for rotation of the motor.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, 1 is a clutch motor body, which includes a clutch mechanism (not shown) for transmitting rotational force to an electric motor 2 and a clutch output shaft 4, and a clutch operating lever 3 that engages with the clutch mechanism.
It is composed of

The electric motor 2 is connected to an AC power source 6 via a bidirectional three-terminal thyristor (hereinafter simply referred to as a thyristor) 5, and a current detector is provided between the electric motor 2 and the thyristor 5 to detect the current flowing through the electric motor 2. 7
is provided. One terminal of this current detector 7 is connected to the ground terminal of the control circuit, and the other terminal is connected to the input terminal of a comparator 9 via a diode 8.
0 and a parallel circuit of capacitor 11 are connected.

Further, a variable resistor 13 is connected between the stabilized DC power supply terminal 12 and the ground terminal, and the input terminal of the comparator 9 is connected to the intermediate terminal thereof. Also,
Variable resistance 1 between trapezoidal wave terminal 14 and ground terminal
5. Connect a series circuit of capacitors 16, and connect a resistor 17 between the interconnection point B and the output terminal of the comparator 9.
A series circuit of diodes 18 is connected. 19
is a unidirectional transistor (hereinafter referred to as
(referred to as UJT), the base B ₂ is connected to the trapezoidal wave terminal 14, the emitter E is connected to the interconnection point RO between the variable resistor 15 and the capacitor 16, and the base B ₁ is connected to the primary winding of the pulse transformer 20. connected to the ground terminal.

Note that one terminal of the secondary winding of the pulse transformer 20 is connected to the cathode of the thyristor 5, and the other terminal is connected to the gate via the diode 21.

Hereinafter, the operation of the present invention will be explained with reference to FIG. A in FIG. 2 shows the waveform of the AC power supply 6. A trapezoidal wave B synchronized with the waveform is generated by a trapezoidal wave generating circuit (not shown), and is input to the trapezoidal wave terminal 14 to form a series circuit of a variable resistor 15 and a capacitor 16. and UJT1
This is the power supply for the CR type phase control circuit consisting of 9. Assume now that when the electric motor 2 is operating under no load, the minimum required voltage under the condition that the rotational speed is not significantly reduced is the waveform D. The firing position of the thyristor 5 by the phase control circuit for obtaining the voltage D is determined by the variable resistor 15. Variable resistance 1 at this time
The waveform at the interconnection point B between 5 and capacitor 16 is shown in C.

FIG. 3 shows the relationship between the rotational speed and current of the motor. Compared to when the motor is operating without load, if the rotational speed decreases, that is, when a load is applied, the current tends to increase. Therefore, the load condition can be detected by detecting the current flowing through the motor. In the above circuit, the current flowing through the motor 2 is detected by the current detector 7, and the current flowing through the motor 2 is rectified by the diode 8 and the capacitor 11. The smoothed signal is input to the input terminal of the comparator 9. Therefore, by means of the variable resistor 13, the voltage value at the input terminal of the comparator 9 is selected to be higher than the voltage at the interconnection point A, which corresponds to the no-load current of the motor 2, and lower than that under load. The output level of comparator 9 is L (low) when there is no load, and H (high) when there is a load.
When a load is applied and the output of comparator 9 becomes H, the waveform at interconnection point B becomes E in Figure 2,
The voltage applied to the electric motor 2 will be F, and the full voltage will be applied.

Note that at this time, the resistance value of the resistor 17 is selected to be much smaller than the resistance value of the variable resistor 15.

On the other hand, when the motor 2 is under no load, the output level of the comparator 9 becomes L, the waveform at the interconnection point RO becomes C in FIG. 2, and the voltage applied to the motor 2 becomes D.

As is clear from the above explanation, the present invention detects the current flowing through the electric motor of the clutch motor and adjusts the detection level to detect whether the clutch is engaged or disengaged. When the clutch is engaged, full voltage is applied to the motor, and when the clutch is disengaged, the minimum necessary voltage is applied without significantly reducing the motor's rotational speed, minimizing power wastage. . Furthermore, in order to obtain the above effects, it can be constructed at low cost using a simple current detector and a phase control circuit.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
The figure is a waveform diagram showing the operation of the circuit, and FIG. 3 is a characteristic diagram showing the relationship between the rotational speed of the motor and the current. 2...Electric motor, 4...Clutch output shaft, 5...
Bidirectional three-terminal thyristor, 6... AC power supply, 7
... Current detector, 9 ... Comparator, 12 ... DC power supply terminal, 14 ... Trapezoidal wave terminal, 19 ... Unijunction transistor, 20 ... Pulse transformer.

Claims (1)

[Scope of utility model registration request] In a clutch motor equipped with a drive section consisting of an electric motor and a clutch mechanism that connects the drive section and a clutch output shaft so as to be able to freely engage and separate, a bidirectional motor is connected between the electric motor and a power source and controls the voltage applied to the motor. a three-terminal thyristor, and the electric motor,
A current detector is installed on the power supply line consisting of a power supply and a bidirectional three-terminal thyristor to detect the current flowing to the motor, and the signal from this current detector is input through a smoothing circuit and the signal level can be adjusted. a comparator that inputs a reference signal, compares the signal level of the signal from the current detector with the signal level of the reference signal, and outputs a signal with different output levels when the motor is operated with a load and when the motor is operated with no load; It includes a bidirectional three-terminal thyristor, an input side is connected to the output side of the comparator, and a signal output from the comparator is inputted, and an output side is connected to the gate side of the bidirectional three-terminal thyristor. and a phase control circuit that controls the conduction angle of the bidirectional three-terminal thyristor in response to a signal from the bidirectional three-terminal thyristor, and the phase control circuit controls the bidirectional three-terminal thyristor in response to a signal from the bidirectional three-terminal thyristor. When the full voltage of the power supply is applied to the motor, and during no-load operation when the clutch is disengaged, the phase control of the bidirectional three-terminal thyristor applies a voltage lower than the minimum total voltage required to maintain the rotation of the motor. A clutch motor characterized in that a voltage is applied to the electric motor.