JPH07289766A - Industrial sewing machine driving equipment - Google Patents

Abstract

PURPOSE:To prohibit driving a motor by turning off a power source switch and a relay to prevent the rush current and to eliminate sewing machine damage, by cutting DC by a coupling condenser in an AC input voltage detection circuit. CONSTITUTION:When AC input power source is applied, electric power is supplied via a filter circuit 1 and a voltage doubler rectifier circuit 2 to an inverter circuit 3 to drive a motor 4 and to a solenoid driving circuit 9. Then a power source circuit 5 and a control circuit 6 respectively start up. In that case, when the power source switch is turned off, the voltage of a smoothing condenser 204 under the voltage doubler rectifier circuit 2 is applied via the coil of a solenoid 901 to an AC input voltage detection circuit 8. DC is cut by a coupling condenser and the input of a protection circuit 7 is made zero to cut the relay driving signal immediately and prohibits to drive a motor 4 by the control circuit 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for an industrial sewing machine.

[0002]

2. Description of the Related Art In recent years, drive devices for industrial sewing machines have mainly come to use an AC servo motor as a drive source for reasons such as maintenance-free operation, long life, and comfortable working environment.

A conventional driving device for an industrial sewing machine will be described below with reference to the drawings. FIG. 2 is a block diagram of a drive device for a conventional industrial sewing machine. 1 is a filter circuit, 2 is a voltage doubler rectifier circuit, 3 is an inverter circuit for converting direct current into alternating current, 4 is an AC servomotor, and 5 is a power supply circuit. ,
6 is a control circuit, 7 is a protection circuit, 80 is an AC input voltage detection circuit, and 9 is a solenoid drive circuit.

The AC input voltage detection circuit includes one AC
It is composed of a diode 81 for half-wave rectifying the input, series resistors 82, 83, 84 forming a voltage dividing circuit, a capacitor 85 for suppressing the ripple of the detection signal, and a smoothing capacitor 85 for the divided output voltage. The solenoid drive circuit includes a transformer 901 for voltage conversion, a rectifier circuit 902, a smoothing capacitor 903, a transistor group 904 for solenoid drive, and a solenoid 905.

In the above structure, when an AC input power is applied, the voltage passes through the filter circuit 1, and then the voltage doubler rectifier circuit 2 supplies power to the inverter circuit 3 for driving the motor 4 and the transformer 901 transforms the rectifier circuit. Electric power is also supplied to the solenoid driver by 902 and the smoothing capacitor 903. Now when the power switch is turned on, the diode 201
The upper smoothing capacitor 203 is charged via the inrush current preventing resistor 205, and in the next half cycle, the lower smoothing capacitor 204 is charged via the inrush preventing resistor 205 and the diode 202. While the above operation is repeated for several cycles, the power supply circuit 5 rises, outputs a plurality of DC voltages insulated from each other, and the control circuit 6 and the protection circuit 7 rise. At this time, if the value input from the AC input voltage detection circuit 80 is a predetermined value or more, the protection circuit 7 outputs a drive signal for the relay 206 and closes the A contact of the relay to prevent the inrush current. By short-circuiting the resistor 205 and reporting the ON state of the relay to the control circuit 6, the entire apparatus enters a standby state in which the sewing machine can be driven.

On the contrary, when the power switch is turned off, the power supply from the filter circuit 1 is stopped. The output voltage of the voltage doubler rectifier circuit 2 spontaneously discharges and gradually decreases. Then, the power ground PG at the AC input voltage detection point
When the voltage for the voltage becomes less than the predetermined value, the protection circuit 7 cuts the relay drive signal, opens the A contact of the relay, reports the OFF state of the relay to the control circuit 6, and prohibits the motor drive to continue the natural discharge. After that, it returns to the initial state.

[0007]

However, in the above configuration, since the voltage of the lower smoothing capacitor 204 is input to the AC input voltage detection circuit via the winding of the solenoid transformer 901, the power switch There is a time delay from turning off the relay to turning off the relay 206. Therefore, if the power switch is turned on again immediately after it is turned off, an inrush current may flow with the contact A of the relay 206 being closed, and the smoothing capacitors 203 and 204 may be damaged. If a drive command for the AC servomotor 4 is output immediately after the power switch is turned off after high-speed operation, the motor slightly rotates, and in the worst case, the sewing machine may be destroyed.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and an object of the present invention is to provide an industrial sewing machine drive device in which a relay is turned off immediately after a power switch is turned off to prohibit motor driving.

[0009]

In order to achieve this object, an industrial sewing machine driving device of the present invention comprises a coupling capacitor connected to one AC input and a plurality of coupling capacitors connected in series to the capacitor. An AC input voltage detection circuit comprising a voltage dividing resistor, a smoothing capacitor for the divided output voltage, a coupling diode between the coupling capacitor and the resistor, and a clamping diode connected to the power ground is provided. The DC voltage component applied to the AC input voltage detection circuit after being turned off can be cut off.

[0010]

With this configuration, the DC voltage of the lower smoothing capacitor applied through the winding of the solenoid transformer is cut by the coupling capacitor, so that the power switch is turned off and the AC input voltage is simultaneously applied. The detection circuit detects power off and outputs it to the protection circuit. The protection circuit turns off the relay drive signal and reports the relay off state to the control circuit to prohibit motor drive.

[0011]

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

In FIG. 1, reference numeral 8 is an AC input voltage detection circuit, which includes a coupling capacitor 801 and a voltage dividing resistor 803.
804, a capacitor 805 for smoothing the detected voltage, and a clamping diode 802. The other components are the same as in the conventional example.

When the power switch is turned off, the voltage of the smoothing capacitor 204 on the lower side of the voltage doubler rectifying circuit 2 is applied to the AC input voltage detecting circuit via the winding of the solenoid transformer 901. Since the DC component is cut off by this, the input of the protection circuit 7 becomes zero, the relay drive signal is immediately cut off, and the control circuit sets the motor drive to the prohibited state.

[0014]

As described above, according to the present invention, the DC component is cut by the coupling capacitor of the AC input voltage detecting circuit, so that the relay can be turned off at the same time when the power switch is turned off to prohibit the motor driving. Therefore, the A contact of the relay is open even if the power is turned on again immediately after the switch is turned off, so that the rush current can be prevented, and the switch is turned off immediately after the sufficient regenerative energy is stored, and the motor drive command is given. Even the motor does not rotate. Therefore, the smoothing capacitor is not damaged, and there is no fear of damaging the sewing machine, and a highly reliable industrial sewing machine drive device can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram of a drive device for an industrial sewing machine according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional industrial sewing machine drive device.

[Explanation of symbols]

 1 Filter Circuit 2 Double Voltage Rectifier Circuit 3 Inverter Circuit 4 Motor 5 Power Supply Circuit 6 Control Circuit 7 Protection Circuit 8 AC Input Voltage Detection Circuit 9 Solenoid Drive Circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H02P 7/63 D

Claims (1)

[Claims] 1. A filter circuit, a voltage doubler rectifier circuit, an inverter circuit, an AC servomotor, a power supply circuit for generating a plurality of insulated DC voltages, a solenoid drive circuit, the AC servomotor and the AC servomotor. A control circuit for controlling the solenoid drive circuit, a coupling capacitor connected to one AC input, a plurality of voltage dividing resistors connected in series with the capacitor, a smoothing capacitor for the divided output voltage, and the cup. An AC input voltage detection circuit including a ring capacitor, a connection point of a resistor, and a clamp diode connected between power grounds, and a protection circuit that detects an abnormality in each part and outputs a protection signal to the control circuit. Industrial sewing machine drive equipped.