JPS6321194Y2 - - 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 running, and the motor is constantly energized. ing.

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 reduce this wasted power, an energy-saving clutch motor has been developed that reduces the voltage applied to the motor when the motor is running without load, supplies the minimum amount of power necessary to rotate the flywheel, and increases the voltage applied to the motor according to the load when the sewing machine is running.

This invention detects the current flowing through the electric motor in an energy-saving clutch motor.
This invention relates to a device that knows the driving state of a sewing machine and controls the voltage applied to the motor.

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

FIG. 1 shows the clutch motor and the main electric circuit. The clutch motor part includes a clutch mechanism 2 for transmitting rotational force to the electric motor 1 and the clutch output shaft 4, and a clutch operation lever that engages with the clutch mechanism 2. It is composed of 3. Furthermore, the main electric circuit section is composed of a bidirectional three-terminal thyristor 6 that controls the voltage applied to the motor 1 from the AC power supply 5. A current detector 7 is provided to detect the current.

Figure 2 shows a control circuit in which a series circuit consisting of a diode 8 and a secondary winding 9 of a pulse transformer is connected between the gate terminal and cathode terminal of a bidirectional three-terminal thyristor 6, and a series circuit is connected between the anode terminal and the cathode terminal. The AC input terminal of the bridge diode 10 is connected to the AC input terminal of the bridge diode 10.

The DC output terminal of the bridge diode 10 is connected to the ground terminal 11, and a series circuit of a resistor 13 and a resistor 14 is connected between the terminal and the ground terminal 11, and the interconnection point A is the input terminal of the operational amplifier 15. is connected to.

Further, an interconnection point RO of a series circuit of a resistor 16 and a resistor 17 connected between the DC power supply terminal 12 and the ground terminal 11 is connected to the input terminal of the operational amplifier 15. In addition, the DC power terminal 12 and the ground terminal 11
The interconnection point C of the series circuit of a resistor 18 and a capacitor 19 connected therebetween is connected to the output terminal of the operational amplifier 15 via a diode 20.

In addition, the sliding terminal of the variable resistor 21 connected between the DC power supply terminal 12 and the ground terminal 11 is connected to the diode 2.
2 to the interconnection point C. Furthermore, an ignition element (hereinafter referred to as UJT) is installed at the interconnection point C.
) 23 emitters are connected and its base
_B2 is connected to the DC power supply terminal 12, and the base _B1 is connected to the ground terminal 11 via the primary winding 24 of the pulse transformer.

On the other hand, one end of the output terminal of the current detector 7 is connected to the ground terminal 11, and the other end is connected to the input terminal of the operational amplifier 26 via a diode 25.
A parallel circuit of a capacitor 27 and a resistor 28 is connected between the input terminal and the ground terminal of the operational amplifier 26, a resistor 29 is connected between the input terminal and the ground terminal, and a resistor 30 is connected between the input terminal and the output terminal. Further, the output terminal is connected to the interconnection point C via a series circuit of a resistor 31 and a diode 32.

Next, the operation will be explained. First, consider the case where no current flows to the motor 1, the potential of the sliding terminal of the variable resistor 21 is OV, and the diodes 22 and 32 are in a reverse blocking state.

In FIG. 3, waveform A is the voltage waveform of AC power supply 5, which is full-wave rectified by bridge diode 10, divided by a series circuit of resistors 13 and 14 (waveform B), and is applied to operational amplifier 15, which is a comparator. Add to input terminal. At the same time, when the voltage applied to the DC power supply terminal 12 is divided by a series circuit of resistors 16 and 17 and the divided voltage B' is applied to the input terminal of the operational amplifier 15, the output waveform becomes C, and the AC power supply A square wave synchronized with 5 is obtained. At the same time, at the interconnection point C, when the voltage charged in the capacitor 19 by the resistor 18 is discharged by the operational amplifier 15 via the diode 20, a waveform D is obtained.

Next, when the potential of the sliding terminal of the variable resistor 21 is increased, the charging speed of the capacitor 19 becomes rapid while the diode 22 is conducting, and the waveform at the interconnection point C becomes E, and the UJT 23 and pulse transformers 9 and 24 cause a bidirectional A signal is applied to the gate terminal of the three-terminal thyristor 6, which becomes conductive, thereby applying voltage to the motor 1 (waveform F).

At the same time, the output voltage of the current detector 7 is rectified by the diode 25, smoothed by the capacitor 27, and applied to the input terminal of the operational amplifier 26, and the output voltage increases according to the amplification factor.
2 becomes conductive and quickly charges the capacitor 19.

At this time, the variable resistor 21 is selected to have the minimum required value for the voltage applied to the electric motor 1 to perform no-load operation within a range in which the rotational speed hardly decreases. Note that the amplification factor of the operational amplifier is determined by the resistors 30 and 29.
determined by the ratio of

Next, when the sewing machine is driven and the current flowing through the motor 1 increases and the voltage applied to the input terminal of the operational amplifier 26 increases, it is amplified according to the amplification factor and becomes higher than the voltage value of the variable resistor 21. When the voltage at the interconnection point C is increased to a voltage of 19, the voltage at the interconnection point C becomes a shape G, and a voltage of a shape H is applied to the motor.

When the current value further increases, the voltage at the interconnection point C becomes a broken shape I, and a voltage of waveform J is applied to the motor.

Therefore, a voltage proportional to the current flowing through the motor 1 is applied to the motor 1.

FIG. 4 shows the relationship between the rotational speed and current of the electric motor 1, where bc is a characteristic curve based on an embodiment of the present invention, and ac is a conventional characteristic curve.

During no-load operation, conventionally the current value a was required, but according to the present invention, the current value can be reduced to the current value b.

As described above, the present invention detects the driving state of the sewing machine by detecting the current flowing through the electric motor of the clutch motor.
By applying a voltage according to this value, the current value at and around the no-load area is reduced, thereby eliminating unnecessary power loss and greatly contributing to energy conservation. Furthermore, vibration and noise during no-load operation are reduced, making sewing work more comfortable.

[Brief explanation of drawings]

Figure 1 is the main electrical circuit diagram of the clutch motor of the present invention, Figure 2 is its control circuit diagram, Figure 3 is a waveform diagram of each part, and Figure 4 is a characteristic diagram showing the relationship between the rotational speed and current of the motor. be. DESCRIPTION OF SYMBOLS 1... Electric motor, 2... Clutch mechanism, 4... Clutch output shaft, 5... AC power supply, 6... Bidirectional three-terminal thyristor, 7... Current detector, 23...
Ignition element, 26... operational amplifier.

Claims (1)

[Scope of utility model registration request] A clutch motor is formed by connecting a drive unit consisting of an electric motor 1 and a clutch output shaft consisting of a load side so that they can be freely engaged and separated by a clutch mechanism, and includes a bidirectional three-terminal thyristor 6 that controls the voltage applied to the electric motor 1. The phase control circuit includes an operational amplifier 15 that obtains a rectangular wave output in synchronization with an AC power supply 5 connected to the motor 1.
, a series circuit of a resistor 18 and a capacitor 19 connected between the DC power supply terminals, and a resistor 18 of this series circuit.
and a ignition element 23 for igniting the bidirectional three-terminal thyristor 6, the input end of which is connected to an interconnection point between the thyristor 6 and the capacitor 19, and whose conduction is controlled according to the potential of the interconnection point; a variable resistor 21 connected between the DC power supply terminals and having its sliding terminal connected to the interconnection point of the resistor 18 and the capacitor 19 to determine the charging time of the capacitor 19 when the motor 10 is in no-load operation; The output signal of the current detector 7 is input to the terminal, and the output terminal is connected to the resistor 18.
and an operational amplifier 26 which is connected to the interconnection point of the and capacitor 19 and controls the conduction angle of the bidirectional three-terminal thyristor 6 according to the output of the current detector 7, and the output of the operational amplifier 15 is The variable resistor 21 is connected to an interconnection point between the resistor 18 and the capacitor 19 to form a discharge circuit for the capacitor 19, and the resistance value of the variable resistor 21 is set to the minimum value required to operate the motor 1 under no load. Naru Clutch Motor.