JP2001332420A - Keep solenoid driving circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a small-sized, simple, and energy-saving keep solenoid driving circuit at a low cost by performing the restoration and attraction of a keep solenoid by means of one control circuit by utilizing the charging currents of capacitors although the conventional keep solenoid driving method uses instantaneous currents for driving the keep solenoid and, accordingly, requires control circuits for sending the instantaneous currents for the restoration and attraction, respectively. SOLUTION: In this keep solenoid driving circuit, capacitors C1 and C2 are respectively connected in series with the restoration and attraction coils of the keep solenoid through relay contacts a1-a4. When the contacts al-a4 are turned on, therefore, the charging current of the capacitor C1 flows through the restoration coil and the keep solenoid is restored (a plunger is protruded). When the relay contacts a1-a4 are turned off and contacts b1-b4 are turned on, the charges charged in the capacitor C1 are discharged and charge the other capacitor C2. Consequently, the charging current of the capacitor C2 flows through the attraction coil and the solenoid attracts. Namely, the keep solenoid is restored and caused to attract with the instantaneous currents (charging currents) by turning on/off relays by means of one ON/OFF control signal.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a keep solenoid. 2. Description of the Related Art A keep solenoid is a combination of a conventional DC general-purpose solenoid and a permanent magnet, and is designed to be attracted only by pulse input (instantaneous energization). After the suction, the plunger is attracted and held by the attractive force of the permanent magnet,
No current is required during that time. Further, the plunger can be opened and returned by an externally mounted spring by inputting a reverse pulse, which saves energy as compared with a conventional DC general-purpose solenoid. FIG. 3 shows a conventional example of a three-wire keep solenoid drive circuit. In the case of the three-wire system, dedicated coils are used for return and suction, respectively. In the figure, the upper half coil of the solenoid is used for return and the lower half coil is used for suction. FIG. 3A shows a case of driving a switch (relay switch), which requires a neutral changeover switch.
1 is turned on instantly to return to neutral, and then S2 is turned on instantly and returned to neutral when required (the order of S1 and S2 may be reversed).
A signal (control) line is required for the ON / OFF operation of OFF and S2. When controlling with a sequencer, two (switching) output terminals are required. FIG. 3 (b) shows a case of driving a transistor, in which two transistors are used, and as described above, each of them is instantaneously turned on to perform return and suction. (The above, for example, CKD strain [0004] In the conventional keep solenoid driving method, one control signal and one relay (or switch) are used for each return / suction in order to operate with an instantaneous current. And two sets are required.
When a transistor (or a switching diode) is used, a switching pulse sending circuit and a switching transistor are required for each, and the cost of manufacturing peripheral circuits for driving these components is high. According to the present invention, it is possible to drive by an instantaneous current by using one ordinary relay (2C contact or 4C contact) and one ON / OFF control signal of the relay. The goal is to get in. In order to achieve the above object, in a keep solenoid drive circuit of the present invention, as shown in FIG. In series with the capacitor C
1 and C2 are connected to each other, and an instantaneous current is applied to the return excitation coil and the attraction excitation coil by using the charging current to the capacitors C1 and C2. The operation of the circuit shown in FIG. 1 will be described below. The illustrated excitation voltage, capacitor capacity, resistance value, and the like of the relay and keep solenoid are merely examples. In particular, the capacitor capacity must be appropriately selected according to the magnitude of the plunger stroke and the magnitude of the solenoid excitation energy depending on the type of solenoid. The relay is a normal 4C contact relay, and is turned ON / OFF by one output terminal of the sequencer. The contact positions shown are when there is no output signal from the sequencer.
The solenoid is in the suction state. A current flows from a solenoid power supply (24V) line to a suction coil via a solenoid terminal 1 and a terminal 2
Then, it reaches the terminal 5 via the relay b2 contact. The current flows from the terminal 5 through the parallel circuit of the capacitor C2 and the resistor R3 to the terminals 7, b
After one contact, it returns to the OV line of the power supply. During this time, the capacitor C2 is charged with a time constant determined by the DC resistance of the attraction coil of the solenoid and the value of the resistor R3.
Voltage is extremely short (several tens of milliseconds to several hundreds of milliseconds)
The charging current (i.e., the exciting current) sharply decreases because the voltage becomes almost 24 V, and settles to a very small current (about 1.2 mA in this circuit) mainly determined by the resistor R3. It will be attracted and held by the permanent magnet. Next, when the sequencer output terminal is turned on and the relay is activated and the contacts a1, a2, a3 and a4 are turned on, the current from the power supply 24V line passes through the solenoid terminal 1, the return coil terminator 3, the relay The current flows through the contacts a3, the terminals 4, 6 and returns to the power supply OV line via the relay contact a4. The capacitor C1 is charged, and the solenoid is returned (the plunger is released) by the charging current, and the plunger is protruded by the external coil spring. Is held. During this time, the electric charge charged in the capacitor C2 is transferred to the terminal 7 via the relay contact a2 and the resistor R4 and reaches the terminal 7 in an extremely short time (0.2 to 0) by the time constant determined by the values of the capacitor C2 and the resistor R4. .3 seconds) and the voltage at the terminal 5 becomes zero.
V, and waits for charging in the next suction operation. Next, when the sequencer output terminal is turned off, the operation returns to the suction operation described in [1] again, and the keep solenoid enters the suction state. Although the operation has been described with reference to the circuit diagram of the three-wire keep solenoid, the polarity of the solenoid power supply is also switched in the case of the two-wire keep solenoid in which the return coil and the suction coil are common. The same purpose can be obtained by adding two C contacts to the same relay. Further, when discharging the electric charge charged in the capacitor, the electric charge is discharged through the coil of the keep solenoid without passing through the discharge resistor, and the circuit is configured so that the electric current can be restored or sucked by this electric current. Is obtained. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Generally, as a usage of a keep solenoid, a plunger is pushed out (returned) for a short time, for example, a micro switch is turned on, an automatic marking is performed, or another actuator is triggered, and then immediately. There are many sequences that return to the suction state and hold it. At this time, the output terminal of the sequencer that controls the solenoid
When it becomes N, the solenoid is restored, the plunger is released and protruded, and then the output terminal is turned off in a short time to bring the solenoid into a suction state. The above-described charge / discharge circuit is incorporated only on the suction coil side. The purpose can be achieved by doing so. Hereinafter, the embodiment will be described with reference to FIG. An embodiment of the present invention will be described based on an embodiment with reference to FIG. The relay of FIG. 2 is a normal 2C contact relay, and is controlled by a control signal from one output terminal of the sequencer.
N / OFF. The illustrated contact position is when the signal from the output terminal of the sequencer is OFF, and the solenoid is in the suction state. As described above, in this state, the capacitor C2 is charged to a voltage close to the power supply voltage of 24 V, and the current flowing through the attraction coil of the solenoid is controlled by the coil DC resistance (several tens Ω to 200Ω) and the resistor R3. Is about 1.2 mA, and the plunger is held in a suction state by a permanent magnet in the solenoid. Next, the sequencer output terminal is turned on,
When the relay is activated and the contacts a1 and a2 are turned ON, current flows through the return coil as described in [0009], and the solenoid is returned to the return state. During this time, the capacitor C2
Is discharged rapidly (0.2 to 0.3 seconds) through the contact a2 and the resistor R2, the voltage of the terminal 5 becomes 0 V, and the charging in the next suction operation is awaited. The required time for the return state is usually 1 second or less, and if the sequencer output is turned off at that time, the relay is turned off, b
The contacts 1 and 2 are turned on, and the operation shifts to the operation described in (1), and the solenoid is in a suction state. According to the present invention, since the circuit is configured as described above, the following effects can be obtained. Conventionally, when driving a keep solenoid,
An ON / OFF control signal with a short ON time is output for each of the return / suction operations in order to operate with an instantaneous current, and the power supply of the solenoid is turned ON / OFF via a relay, or a solenoid is used by using a switching pulse sending circuit and a switching transistor. Was turned on / off, but in this case, a simple circuit consisting of one normal relay (2C contact or 4C contact), one control signal for turning on / off this relay, and only passive elements, Both return and suction can be driven by an instantaneous current, and compact, simple, and energy-saving can be achieved at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of a keep solenoid drive according to the present invention. FIG. 2 is a circuit diagram showing an embodiment of the present invention for driving a keep solenoid. FIG. 3 is a circuit conceptual diagram showing a conventional example of keep solenoid drive. [Description of Signs] 1: Input terminal of solenoid exciting coil 2: Terminator of solenoid attraction coil 3: Terminator of solenoid return coil 4, 5: + terminal of electrolytic capacitor 6, 7:-terminal a1, a2 of electrolytic capacitor , A3, a4: relay contacts (turn on when the relay is on) b1, b2, b3, b4: relay contacts (relay is off
ON at the time. C1, C2: Electrolytic capacitors D1, D2, D3: Coil protection diodes R1, R3: Electrolytic capacitor protective resistors R2, R4: Electrolytic capacitor discharge resistors S1, S2: Changeover switch (with neutral) T1, T2: Switching Transistor (switching diode)

Claims (1)

Claims 1. A terminal 2 of a suction coil and a terminal 3 of a return coil of a keep solenoid are connected in series via switches or relay contacts b2 (ON) and a3 (OFF), respectively. When the contact b2 is turned off and the contact a2 is turned on and the contact b3 is turned off and the contact a3 is turned on, the discharge resistor R4 is connected to the capacitors C2 and C1 so that the capacitor C2 is short-circuited through the contact a2.
Is connected, the discharge resistor R2 that short-circuited the capacitor C1 through the contact b3 is disconnected, and the terminal 4 of the capacitor C1 is connected to the terminator 3 of the return coil through the contact a3. . 2. A capacitor C2 is connected in series to a terminal 2 of a suction coil of a keep solenoid via a switch or a relay contact b2, and the other end of the capacitor is connected to an OV line of a solenoid power supply via a contact b1. When the switch or the relay is turned on (ON), the discharge resistor R2 is connected so as to short-circuit the capacitor through the switch or the relay contact a2,
A keep solenoid drive circuit also composed of a circuit connected so that an exciting current flows through the return coil through the contact a1. 3. In the same spirit as in [1] and [2], a capacitor is charged / removed in order to obtain an instantaneous current required to drive a keep solenoid.
Other drive circuits that use discharge current.