JP2007059729A - Electromagnet controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnet controller capable of operating an electromagnet with a small coil very frequently through a process of detecting that a movable iron core reaches to a suction position so as to control the shutoff timing of an exciting current flowing through a suction coil, and making the duration of the exciting current the shortest. <P>SOLUTION: The electromagnet controller is equipped with a suction coil 5 that enables a stationary iron core 7 to attract a movable iron core 6, a holding coil 4 that retains the state that the movable iron core 6 is attracted to the stationary iron core 7, and a limit switch 14 that is mechanically opened when the movable iron core 6 reaches at a suction position. A series circuit composed of the suction coil 5 and the limit switch 14 and the holding coil 4 are connected in parallel to a power supply. The suction coil 5 is released from magnetization by the limit switch 14, so that the duration of an exciting current flowing through the suction coil 5 can be set short, and moreover the coil can be restrained from rising in temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a direct current excitation type electromagnet control device configured to be driven with a large excitation current during an attraction operation of an electromagnet that attracts a movable iron core and to decrease the excitation current of a coil after adsorption.

  Since the electromagnet before the suction has a gap between the movable iron core and the fixed iron core, a large exciting current is required to attract the movable iron core against the return spring. However, since there is no gap after the suction operation, the attracted state can be maintained with a small excitation current. In the case of an electromagnet with AC excitation, there is no problem because the impedance of the coil is automatically increased at the same time that the movable iron core is attracted to the fixed iron core and the excitation current is reduced. However, in the case of a DC-excited electromagnet, there is no change in impedance even when the movable iron core is attracted, so the excitation current does not decrease. In order to energize this exciting current for a long time, it is necessary to use a thick wire, and the coil becomes large. Therefore, a method is often employed in which a small electromagnet is obtained by driving with a large excitation current during an attraction operation and reducing the excitation current by a voltage switching circuit or voltage switching at a predetermined cycle after the attraction operation is completed.

  Conventionally, as such a DC excitation type electromagnet control apparatus, there is an electromagnet control apparatus disclosed in, for example, Japanese Utility Model Publication No. 60-11606 as shown in FIG. In FIG. 3, 1 is an AC power source, 2 is a rectifier that rectifies the AC power source by full-wave rectification, and 3 is a control switch that supplies power, 4 is a holding coil that generates a holding suction force connected in parallel with the rectifier 2, and 5 A suction coil that generates an initial suction force, 6 is a movable iron core that performs a suction operation by the initial suction force of the suction coil 5, and 7 is a fixed iron core that faces the movable iron core.

  Reference numeral 8 denotes a first thyristor which is a first switching element connected in series to the suction coil 5 and is conductive during the initial attractive force. Reference numeral 9 denotes a capacitor connected between the gate and the anode of the first thyristor 8. Reference numeral 10 denotes a second thyristor which is a second switching element for applying a reverse bias to the first thyristor 8 by the electric charge of the capacitor 9, reference numeral 12 denotes a resistor, reference numeral 13 denotes a Zener diode 11 which constitutes a timer circuit together with the resistor 12. A capacitor 11 connected to (described later) is a Zener diode that conducts when the charging voltage of the capacitor 13 reaches a predetermined value or more.

  Next, the operation of the conventional electromagnet control apparatus configured as described above will be described with reference to FIG. When the control switch 3 is closed, the holding coil 4 is excited. Further, the first thyristor 8 is conducted and the suction coil 5 is excited, so that the open movable core 6 is attracted and attracted to the opposed fixed core 7.

  The charging time of the capacitor 13 of the timer circuit is set to a time sufficient to exceed the operating voltage of the Zener diode 11 after the suction completion time of the movable iron core 6. After the movable iron core 6 is attracted to the fixed iron core 7, when the Zener diode 11 is turned on by the timer circuit, the second thyristor 10 is turned on. When the second thyristor 10 is turned on, a reverse bias is applied to the first thyristor 8 by the capacitor 9, the first thyristor 8 is extinguished, and the excitation of the suction coil 5 is released.

However, since the holding coil 4 is excited, the movable core 6 and the fixed core 7 are kept attracted by a small holding suction force. When the control switch 3 is opened, the excitation of the holding coil 4 is released and the movable iron core 6 returns to the original open state by the force of the return spring.
Japanese Utility Model Publication No. 60-11606

  Since the electromagnet control device of FIG. 3 is configured as described above, the excitation current of the attraction coil is interrupted by a timer circuit that is set to be longer than the expected attraction completion time without detecting the position of the movable iron core. . However, if the set time of the timer is lengthened in order to perform suction more reliably, there has been a problem that the coil temperature rises and high-frequency operation cannot be performed.

  Therefore, the main object of the present invention is not to control the excitation current cutoff timing of the suction coil by time, but to detect and control that the movable iron core has reached the adsorption position, and to apply the excitation current energization time. It is to provide an electromagnet control device that enables high-frequency operation of an electromagnet having a small coil.

  An electromagnet control device according to the present invention is a control device that controls a DC excitation type electromagnet, an attraction coil that attracts the movable iron core to the fixed iron core, a holding coil that maintains the attracted state of the movable iron core and the fixed iron core, and the movable iron core And a limit switch that is mechanically opened when reaching the suction position, and a series circuit of a suction coil and a limit switch and a holding coil are connected in parallel to the power source.

  According to the electromagnet control device of the present invention, the excitation current of the attraction coil is interrupted by the limit switch that operates by detecting that the movable iron core has reached the attracting position. The energization time is short, and the coil temperature can be kept low. As a result, high-frequency operation of an electromagnet having a small coil can be realized very easily.

  Embodiments of the present invention will be described with reference to the examples shown in FIGS. In addition, the substantially same member as the conventional apparatus shown in FIG. 3 is demonstrated using the same code | symbol. 1 and 2, a rectifier 2 is connected to an AC power source 1 through a control switch 3, and performs full-wave rectification on an AC voltage applied to an input terminal. The holding coil 4 is connected between the output terminals of the rectifier 2 and is always supplied with current when the control switch 3 is closed. The suction coil 5 is connected in series with the limit switch 14 and is connected between the output terminals of the rectifier 2. The limit switch 14 is a normally closed contact that is ON when the movable core 6 is separated from the fixed core 7, and is mechanically opened and closed by the operation of the movable core 6. The diode 15 is connected in parallel to the suction coil 5 in reverse polarity so that an overvoltage is not generated in the suction coil 5 when the limit switch 14 is opened.

  Next, this operation will be described. When the control switch 3 is closed, both the holding coil 4 and the suction coil 5 are excited simultaneously. When the movable iron core 6 reaches a position where it is attracted to the fixed iron core 7, the limit switch 14 is opened. Therefore, the excitation of the attracting coil 5 is released, and the movable iron core is attracted only by the attracting force of the holding coil 4.

  Next, when the control switch 3 is opened, the excitation of the holding coil 4 is released, and the movable iron core 6 is separated from the fixed iron core 7 by the force of the return spring to return to the original open state.

  As described above, according to the electromagnet control device of the present embodiment, the movable iron core reaches the attracting position without using the timer circuit in which the exciting current of the attraction coil is interrupted more than the conventional expected completion time. Since this is performed by a limit switch that operates by detecting this, the energization time of the excitation current is short and the coil temperature can be kept low. As a result, high-frequency operation of an electromagnet having a small coil can be realized very easily.

It is a circuit diagram which shows one Example of the electromagnet control apparatus which concerns on this invention. It is sectional drawing which shows one Example of the electromagnet control apparatus which concerns on this invention. It is a circuit diagram which shows the conventional electromagnet control apparatus.

Explanation of symbols

1 AC power supply 2 Rectifier 3 Control switch 4 Holding coil 5 Suction coil 6 Movable iron core 7 Fixed iron core 14 Limit switch 15 Diode

Claims (1)

In a control device that controls a DC excitation type electromagnet,
A suction coil that attracts the movable core to the fixed core;
A holding coil for maintaining the adsorbed state of the movable core and the fixed core;
A limit switch that mechanically opens when the movable iron core reaches the adsorption position;
An electromagnet control device, wherein a series circuit of the attraction coil and the limit switch and the holding coil are connected in parallel to a power source.

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