JPH079852B2 - Electromagnet drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention allows a continuous current to flow through an electromagnet operating coil when an electromagnet is turned on, and an intermittent current to flow when the electromagnet is held, and after the iron core is attracted, the iron core is attracted. The present invention relates to an electromagnet drive device that reduces the power consumption by switching to an intermittent current that holds the current.

[Prior art]

A circuit diagram of a conventional electromagnet driving device of this type is shown in FIG. In the figure, by turning on the closing switch 2, the AC voltage of the single-phase AC power supply 1 is applied to the AC terminal of the full-wave rectifier circuit 9 composed of a diode bridge circuit. The DC terminal of the full-wave rectifier circuit 9 is connected to a series circuit of the electromagnet operating coil 5 and the collector-emitter passage of the switching transistor 6, and is also connected to the drive circuit 7. Reference numeral 3 is a noise absorbing capacitor, 4 is a flywheel diode, and 8 is a line inductance. As shown in the time chart of FIG. 5, the drive circuit 7 has a pulse of a constant time width T necessary for attracting the movable iron core of the electromagnet when the closing switch 2 is turned on (hereinafter, a pulse for continuing the ON state in this way). A continuous pulse) to the base of the switching transistor 6, and after the movable iron core is attracted, the pulse is repeatedly turned on and off at a period required to hold the movable iron core (hereinafter, on and off in this manner). Is applied to the base of the switching transistor 6. As a result, an intermittent current is applied to the operation coil 5 of the electromagnet after the movable iron core is attracted, so that power consumption can be reduced.

[Problems to be solved by the invention]

As described above, the switching transistor 6 is caused to perform a switching operation in order to reduce the power consumption, and the capacitor 3 is connected to eliminate the switching noise due to this switching operation. However, a sudden charging current flows from the power source 1 through the closing switch 2 to the capacitor 3 at the moment when the closing switch 2 is turned on, and depending on the capacities of the capacitor 3 and the closing switch 2, a contact point of the closing switch 2 may occur. It causes welding, wear of the contacts, and deterioration of the capacitor 2. When a solid state relay or other semiconductor switch is used as the closing switch 2, a series resonance phenomenon occurs due to the power source 1, the switch 2, the capacitor 3 and the line inductance 8 and a reverse voltage is applied to the semiconductor switch, so that it is turned on / off. As a result, the capacitor 3 has a drawback that it deteriorates due to rapid charging and discharging and adversely affects the operating coil 5.

Therefore, an object of the present invention is to provide a highly reliable electromagnet device which eliminates the drawbacks of the conventional device and prevents welding of the closing switch contact and deterioration of the capacitor without adding any parts.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention is configured such that a closing switch, an electromagnet operating coil and a switching element are connected in series to a power source, a noise absorbing capacitor is connected in parallel to the operating coil and the switching element, and the switching is performed. In an electromagnet drive device having a drive circuit that supplies continuous pulses when an electromagnet is turned on to an element and intermittent pulses when holding the element, the operation coil is divided into two at an appropriate ratio, and one of the divided coils is provided. Is inserted in the charging circuit of the noise absorbing capacitor.

[Action]

The coil for electromagnet operation is divided into two parts at an appropriate ratio, and one coil is connected to the charging circuit of the noise absorption capacitor and used as a choke coil, so that the circuit impedance from the power supply to the noise absorption capacitor is increased. This makes it possible to prevent the charging current from suddenly flowing to the noise absorbing capacitor at the moment when the closing switch is turned on.

Example of Invention

1 and 3 each show an embodiment of the present invention. In FIG. 1, the same parts as those of the conventional apparatus shown in FIG.

1 is different from the conventional device shown in FIG. 4 in that the electromagnet operating coil is divided into two parts, a coil 51 and a coil 52, at an appropriate ratio, and the coils 51 and 52 are a power source 1 and a switching switch.
2, the switching transistor 6 is connected in series with the collector / emitter path, the coil 51 is connected to the closing switch 2 side of the noise absorbing capacitor 3, and the noise absorbing capacitor 3 is connected to the coil 52 and the switching transistor 6 Connected in parallel to the emitter passage,
The flywheel diode 4 is connected to the coil 52 in parallel. FIG. 3 is a structural diagram of the electromagnet device, in which the E-shaped fixed iron core 50 is provided with the divided coils 51 and 52, and the movable iron core 53 is arranged so as to face the fixed iron core 50.

In FIG. 1, when the closing switch 2 is closed, the drive circuit 7 supplies a continuous pulse having a constant time width T as shown in FIG. During the closing operation of the electromagnet in which continuous pulses are applied from the drive circuit 7 to the base of the switching transistor 6, the coils 51, 52
Currents i1 and i2 having the same value flow in the. As a result, a large attraction force acts on the movable iron core of the electromagnet, and it is attracted to the fixed iron core to complete the loading operation. After the closing operation is completed, intermittent pulses are applied from the drive circuit 7 to the base of the switching transistor, and the switching transistor 6 starts the switching operation. While the switching transistor 6 is off, the capacitor 3 is charged via the coil 51. A current flows and is charged. While the switching transistor 6 is on, the capacitor 3 is discharged through the coil 52, and the coil 52 holds the electromagnet. Since the coil 51 functions as a choke coil because the coil 51 is inserted closer to the closing switch 2 side than the capacitor 3, the circuit impedance from the power supply 1 to the capacitor 3 becomes high, and the moment the closing switch 2 is closed. Therefore, the charging current does not suddenly flow into the capacitor 3 and the contacts of the closing switch 2 do not weld.

A difference occurs between the currents flowing through the operating coil through the coil 51 and the coils 51 and 52. This is because if the ratio of division into the coils 52 is set to 1: 1, since a flywheel diode is connected to each coil 52 during the holding operation of the electromagnet, the coil 52 acts from the current flowing through the coil 51 acting as a choke coil.
The current flowing through it increases. Therefore, each coil 51,52
Since there is a difference in temperature rise, it is preferable to reduce the ratio of the coil 51 acting as the choke coil.

〔The invention's effect〕

As described above, the electromagnet operating coil is divided into two at an appropriate ratio, and one of the divided coils is inserted into the charging circuit of the noise absorbing capacitor. The line impedance up to the absorption capacitor can be increased, and the current that flows when the closing switch is closed can be limited by the coil acting as a split choke coil, welding of the contacts of the closing switch and deterioration of the capacitor. Can be prevented. Further, it is possible to prevent the series resonance phenomenon from occurring by selecting the inductance and resistance of the coil acting as the choke coil to appropriate values.

[Brief description of drawings]

1 and 3 each show an embodiment of the present invention. FIG. 1 is a circuit diagram of an electromagnet driving device, FIG. 2 is a waveform diagram of essential parts, and FIG. 3 is a configuration diagram of essential parts of the electromagnet device. 4 and 5 are a circuit diagram and a waveform diagram showing a conventional device, respectively. 1: Power supply, 2: Switching switch, 3: Capacitor, 6: Switching transistor, 7: Driving circuit, 51, 52: Coil.

Claims (1)

[Claims] 1. A closing switch, an electromagnet operating coil and a switching element are connected in series to a power source, a noise absorbing capacitor is connected in parallel to the operating coil and the switching element, and when the electromagnet is turned on to the switching element. In an electromagnet drive device having a drive circuit that supplies continuous pulses and supplies intermittent pulses when holding,
An electromagnet drive device characterized in that the operating coil is divided into two parts at an appropriate ratio, and one of the divided coils is inserted into a charging circuit of a noise absorbing capacitor.