JPH04293207A - Electromagnet apparatus - Google Patents

Abstract

PURPOSE:To obtain an electromagnet apparatus wherein the shock when a moving core is attracted by a fixed core is reduced. CONSTITUTION:A position sensor 8 for detecting the position of a moving core 9 is installed. When an attracting surface 9A of the movable core 9 reaches a specified position in this side of the attracting surface 10A of a fixed core 10, a making current of large current value flowing through a coil 1 wound around the fixed core 10 is switched to a holding current of small current value.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnet device used in an electromagnetic switch or the like.

0002

2. Description of the Related Art FIG. 4 is a circuit diagram including a model of a part of a conventional electromagnet device. In FIG. 4, an electromagnet 11 consists of a movable core 9 and a fixed core 10, and attracts the movable core 9 to the fixed core 10 by passing a current through a coil 1 wound around the fixed core. Coil 1 is connected to input terminal PN via transistor 2, and diode 3 is connected across coil 1. The signal generating circuit 12 is usually made as an IC, and includes a voltage detecting section 5 that determines whether the input voltage is within a predetermined range and outputs an operating signal V1 to the power supply section 4 of the IC; The one-shot timer section 6 receives the operation signal V1 from the voltage detection section 5 and outputs the closing pulse signal V2 of the electromagnet 11 based on the operation signal V1. It is connected to an oscillating section 7 which outputs a holding pulse signal V3 of the electromagnet 11 which is repeated at a constant cycle after V2 ends. The input pulse signal V2 of the one-shot timer section 6 and the holding pulse signal V3 of the oscillation section 7 are input to the transistor 2, respectively.

FIG. 5 is an operation chart of this electromagnet device. When an input DC voltage is applied to the terminals P-N [(1) in FIG. 5], the voltage detection section 5 detects whether this voltage is within a predetermined range. In this case, the operation signal V1 is output [(2) in FIG. 5]. This operation signal V1 is input to the one-shot timer section 6, and the one-shot timer section 6 outputs a closing pulse signal V2 with a time width TP sufficient to attract the movable iron core.
(3) in Figure 5]. This input pulse signal V2 is input to transistor 2, and transistor 2 is turned on. By turning on transistor 2, the circuit of terminal P-coil 1-transistor 2-terminal N becomes conductive, and coil 1
A current flows through and attracts the movable iron core 9. On the other hand, the input pulse signal V2 is also input to the oscillator 7, and the oscillator 7 outputs the holding pulse signal V3 which is repeated at a constant period after the input pulse signal V2 ends [Fig. 5-(5)
]. This holding pulse signal V3 is input to the transistor 2, and the transistor 2 repeats turning on and turning off according to the period of this holding pulse signal V3. Figure 5
-(6) indicates the voltage applied to the coil 1 by the input pulse signal V2 and the holding pulse signal V3. In response to the closing pulse signal V2, a closing current having a large enough current value and time width TP to attract the movable iron core 9 flows through the coil 1, and the movable iron core 9 is attracted. Closing pulse signal V
2, a holding current of a small value enough to maintain the adsorbed state of the movable iron core 9 flows by the holding pulse signal V3, and the movable iron core 9 is held in the adsorbed state. Note that this holding current caused by the holding pulse signal V3 becomes a constant current due to the flywheel effect of the diode 3 regardless of the pulse signal that repeats at a constant cycle [Figure 5-
(7)].

0004

[Problem to be Solved by the Invention] In the above-mentioned electromagnet device, in order to prevent suction errors caused by variations in the load coupled to the movable core, variations in the frictional force of the moving parts, variations in input voltage, etc., it is necessary to The time width of the current is set to be very long. In other words, in the current flowing through the coil shown in Figure 5 (7), there is a point where the current value decreases once at time A after the input current rises, but this decrease in current value occurs exactly at time A when the movable iron core This is due to the fact that the inductance of the coil wound around the fixed core increases due to adsorption of the fixed core to the fixed core. If there were no variations mentioned above, it would be possible to turn off the supply current at this time, but in reality, these variations may cause a mistake in which the movable core is not attracted, and as shown in the figure, the time width of the supply current may be cut off. TP has a very long time span extending to time B, which is sufficiently longer than time A.

For this reason, when the movable core is attracted to the fixed core, the impact becomes large, and the bounce time of the contacts of, for example, an electromagnetic switch connected to the movable core becomes longer, reducing the life of the contacts, or especially Large electromagnetic switches may cause problems such as surrounding equipment malfunctioning due to the impact.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide an electromagnet device in which the impact when a movable core is attracted to a fixed core is minimized.

[0007]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention includes a movable iron core, a fixed iron core around which a coil is wound, a transistor connected in series to the coil, and a transistor connected to the transistor in series. Outputs a closing pulse signal that attracts the connected movable iron core to a fixed iron core, and a holding pulse signal that repeats at a constant period after this closing pulse signal stops, and keeps this transistor in a conductive state while these signals are being outputted. In an electromagnetic device, the position of the movable core is detected in an electromagnetic device comprising a signal generating circuit that generates a signal, and a diode connected between both ends of the coil, and in which an input DC voltage is applied to the coil and the transistor connected in series. a position sensor is provided, and when the suction surface of the movable iron core comes to a predetermined position in front of the suction surface of the fixed iron core, the position sensor outputs a signal to the signal generator;
The input pulse signal of this signal generator is switched to a holding pulse signal.

[0008]

[Operation] In the electromagnet device of the present invention, a position sensor is provided to detect the position of the movable core, and this position sensor detects the movement of the movable core so that the attracting surface of the movable core is positioned slightly in front of the attracting surface of the fixed core. When this happens, the input pulse signal is switched to the hold pulse signal. As a result, the current flowing through the coil is switched from the input current, which has a large current value, to the holding current, which has a small current value, and the impact when the movable iron core is attracted to the fixed iron core becomes extremely small. In addition, the stop position of the closing pulse signal is set at a predetermined position slightly before the attraction surface of the fixed core where the attraction force of the movable core due to the holding current is greater than the load force of the movable core, so the movable core is reliably attracted. It will be done.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a circuit diagram including a partial model showing an embodiment of an electromagnetic device according to the present invention. The electromagnet device of the present invention shown in FIG. 1 is different from the conventional electromagnet device shown in FIG. This is at the point inputted to the one-shot timer section 6.

FIG. 2 is an operation chart of this electromagnet device. When an input DC voltage is applied to the terminals P-N [(1) in FIG. 2], the voltage detection section 5 detects whether this voltage is within a predetermined range In this case, the operation signal V1 is output [(2) in FIG. 2]. The process up to this point is the same as the conventional electromagnet device shown in FIG. This operation signal V1 is input to the one-shot timer section 6, and the one-shot timer section 6 outputs the input pulse signal V2 [(3) in FIG. 2]. This input pulse signal V2
is input to transistor 2, and transistor 2 is turned on. When the transistor 2 is turned on, the circuit consisting of the terminal P, the coil 1, the transistor 2, and the terminal N becomes conductive, and current flows through the coil 1, which acts to attract the movable iron core 9. The movable core 9 moves toward the fixed core 10, and this movement is detected by the position sensor 8 and the adsorption surface 9A of the movable core 9
outputs a signal at a position slightly in front of the attraction surface 10A of the fixed iron core 10 [(4) in FIG. 2]. This output signal is input to the one-shot timer section 6, and the one-shot timer section 6 stops outputting the input pulse signal V2. The time width Tq of the input pulse signal V2 is determined in this way [Fig. 2
(3)]. By stopping the input pulse signal V2, the input current is cut off as shown in (7) in Figure 2, and the holding pulse signal V3 is outputted from the oscillator 7 as shown in (5) in Figure 2. Current flows.

FIG. 3 is a characteristic diagram that partially includes a model to explain the suction operation of the movable core 9. Taking an electromagnetic switch as an example, the horizontal axis represents the position of the movable core 9, and the vertical axis represents the attraction force of the movable core 9. M and the loading force of the movable core are depicted. The movable core 9 is moved from the open position toward the closed position (suction position) by the large attraction force M1 of the input current generated by the input pulse signal, so that the attraction surface 9A of the movable core 9 is slightly in front of the attraction surface 10A of the fixed core 10. Position sensor 8 detects when the position is reached.
is detected. The input pulse signal is switched to a holding pulse signal by the output signal from the position sensor 8, and the movable iron core 9
is attracted to the fixed iron core 10 with a very small impact by the small attractive force M2 caused by the holding current. In this case, the detection position of the movable core 9 is the position where the attraction force M2 due to the holding current is greater than the load force L of the movable core 9, and is located closer to the attraction surface of the fixed core than the position S in FIG. The iron core 9 is reliably attracted.

The position sensor 8 may be a proximity switch that is installed near the movable core 9 and directly detects the position of the movable core 9, or a proximity switch that is attached to a member that moves in conjunction with the movable core 9 to detect when the movable core 9 is at a predetermined position. A limit switch, a reed switch, or an auxiliary contact of an electromagnetic switch to which this electromagnetic device is attached is used.

The operation after the movable core is attracted is the same as that of the conventional electromagnet device shown in FIG.

[0014]

[Effects of the Invention] In the electromagnet device of the present invention, a position sensor is provided to detect the position of the movable core, and this position sensor detects the movement of the movable core so that the attracting surface of the movable core is located slightly before the attracting surface of the fixed core. When the coil reaches the position, the current in the coil is switched from a high-value input current to a low-value holding current to reduce the impact when the movable core sticks to the fixed core. As a result, for example, the bounce time of the contacts of an electromagnetic switch is shortened and the contact life is extended, and of course, especially in large electromagnetic switches, surrounding equipment will not malfunction due to the shock. Furthermore, the time width of the input current flowing through the coil is shorter than before, so
In particular, the rise in coil temperature during high-frequency switching is suppressed to a low level, making it possible to withstand high-frequency switching.

[Brief explanation of drawings]

[Fig. 1] A circuit diagram including a partial model showing an embodiment of the electromagnet device of the present invention.

[Fig. 2] Operation chart of the electromagnet device of the present invention shown in Fig. 1

[Fig. 3] Characteristic diagram including a partial model explaining the adsorption operation of the electromagnet device of the present invention shown in Fig. 1.

[Figure 4] Circuit diagram including a partial model of a conventional electromagnet device

[
Figure 5: Operation chart of the conventional electromagnet device shown in Figure 4

[Explanation of symbols]

1 Coil 2 Transistor 3 Diode 8 Position sensor 9 Movable iron core 9A Adsorption surface 10 Fixed core 10A Adsorption surface 12 Signal generation circuit

Claims (5)

[Claims] 1. A movable iron core, a fixed iron core around which a coil is wound, a transistor connected in series to the coil, a closing pulse signal connected to the transistor to attract the movable iron core to the fixed iron core, and this closing pulse signal. a signal generating circuit that outputs a holding pulse signal that repeats at a constant period after the pulse signal stops and keeps the transistor in a conductive state during the period when these signals are output; and a diode connected between both ends of the coil. In the electromagnet device, in which an input DC voltage is applied to the coil and the transistor connected in series, a position sensor is provided for detecting the position of the movable core, and the attracting surface of the movable core is attached to the attracting surface of the fixed core. An electromagnet device characterized in that when the electromagnetic device reaches a predetermined position in front of a surface, a signal is output from the position sensor to the signal generator, and the input pulse signal of the signal generator is switched to a holding pulse signal. 2. The electromagnet device according to claim 1, wherein the position sensor comprises a proximity switch provided near the movable iron core. 3. The electromagnet device according to claim 1, wherein the position sensor comprises a limit switch attached to a member that moves in conjunction with the movable iron core. 4. The electromagnet device according to claim 1, wherein the position sensor comprises a reed switch attached to a member that moves in conjunction with the movable iron core. 5. The electromagnet device according to claim 1, wherein the position sensor comprises an auxiliary contact of an electromagnetic switch to which the electromagnet device is attached.