JPH07190233A - Solenoid exciting circuit - Google Patents

Abstract

PURPOSE:To prevent malfunction caused to a fluid actuator at the time of operating an emergency stop button. CONSTITUTION:One ends of coils 20A, 20B of solenoids which are different in rated electric currents and an electromagnetic relay are connected to one electrode of a direct current electric source 19 through an emergency stop button 18 and simultaneosly, the other ends are connected to the other electrode of the direct current electric source 19 through electric power amplifying elements 5A-5C carrying out on and off actuation. Additionally, a constantly opened contact point 21 of the electromagnetic relay 17 is serially connected to a coil 20C of the solenoid the rated electric current of which is larger than the maximum rated electric current of the electric power amplifying elements, it is connected to the direct current electric source 19 and a serial circuit of the emergency stop button 18 in parallel, and a diode 21 is connected to the direct current electric source 19 in reverse polarity in parallel with the coil 20C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid exciting circuit for exciting a plurality of solenoids by supplying an exciting current to coils of a plurality of solenoids having different rated currents by turning on a power amplification element.

[0002]

2. Description of the Related Art Conventionally, there is a solenoid excitation circuit of this type shown in FIG. This is a controller 30 that outputs a signal for exciting a solenoid in accordance with a pre-programmed procedure, and a field effect transistor 31A, for example, as a power amplification element that is turned on and off by inputting the signal output from the controller 30. 31B, 31C
And these field effect transistors 31A, 31B, 31
Programmable with a plurality of output terminals 33A, 33B, 33C connected to the drain terminals 32A, 32B, 32C of C and a power supply terminal 36 connecting the source terminals 34A, 34B, 34C via a common power supply line 35 A controller 37 is provided, and the output terminals 33A, 33B, 33C of the programmable controller 37 are respectively connected to a plurality of solenoid coils 38A, 38 having different rated currents.
The solenoid coils 38A, 38B, and 38C are connected to one end of the DC power supply 40 through the emergency stop button 39, which has a normally closed contact. Connected to the power supply terminal 36, the DC power supply 40 supplies an exciting current corresponding to the rated current to the coil of the corresponding solenoid by the ON operation of the field effect transistors 31A, 31B, 31C, and electromagnetic switching is performed by the solenoid excited by the exciting current. The valve is switched and controlled to drive the fluid actuator.
41A, 41B and 41C are flywheel diodes which form a protection circuit, and 42 is a fuse.

However, in this case, the output terminals 33A, 3
Solenoid coils 38A, 3 connected to 3B, 33C
Since the rated currents of 8B and 38C are large and small, the output terminals 33A, 33B and 33C are erroneously connected to a solenoid coil having a rated current higher than the maximum rated current of the field effect transistors 31A, 31B and 31C. If this happens, only the current specified by the maximum rated current can flow through the coil of the solenoid, which causes a problem in that the solenoid is not sufficiently excited and the electromagnetic switching valve causes switching malfunction. Therefore, the applicant of the present invention replaces, for example, a solenoid coil 38A whose rated current of the solenoid coil is not less than the maximum rated current of the field effect transistor with an electromagnetic relay, and replaces the normally open contact of the electromagnetic relay with the solenoid. Coil 38
A circuit in which the normally open contact of the electromagnetic relay and the coil 38A of the solenoid are connected in series is connected to the DC power supply 4
0 and the emergency stop button 39 are connected in parallel to the series circuit, and the electromagnetic relay is excited by the ON operation of the field effect transistor 31A to close the normally open contact of this electromagnetic relay, and the exciting current corresponding to the rated current is supplied to the solenoid coil 38A. Was supplied from the DC power supply 40.

[0004]

However, in this device, an uncontrollable abnormality such as runaway or malfunction occurs in the fluid actuator while the field effect transistor 31A is in the on-operation, and the fluid actuator is urgently stopped. When the emergency stop button 39 is pressed, the coil 38A of the solenoid, which is energized with the exciting current, induces a counter electromotive force at the moment when it is cut off from the DC power supply 40 by the operation of the emergency stop button 39. Further, the electromagnetic relay has a response delay time when the normally open contact shifts from the closed state to the open state due to the mechanical response delay even if the electromagnetic relay is demagnetized by turning off the field effect transistor 31A by operating the emergency stop button 39. is doing. Therefore, an impulse current having a waveform that rapidly rises based on the counter electromotive force and then attenuates flows into the power supply terminal 36 of the programmable controller 37 from the solenoid coil 38A. This impulse current is transmitted through the common power line 35 to the field effect transistors 31B and 31C.
The flywheel diodes 41B and 41C are energized from the source terminals 34B and 34C of the above, and the coils 38B and 38C of the other solenoids connected to the output terminals 33B and 33C of the programmable controller 37 are energized.

For this reason, when an uncontrollable abnormality such as runaway or malfunction occurs in the fluid actuator, even if the emergency stop button 35 is operated to stop the fluid actuator in an emergency, the operating fluid actuator immediately stops. Do not do this, or operate the fluid actuator while it is stopped, while the impulse current is decaying.In addition, if the solenoid switching valve has a detent mechanism, the impulse current is applied to the solenoid coil. If the electromagnetic switching valve is switched in the meantime, the switched state is maintained, which causes a new malfunction of the fluid actuator controlled by the electromagnetic switching valve.

The present invention solves these problems.
To prevent malfunction that occurs in the fluid actuator when the emergency stop button is operated when the fluid actuator is driven by exciting a plurality of solenoids having different rated currents with a power amplifier connected to a common DC power supply. It is an object of the present invention to provide a solenoid excitation circuit having the above structure.

[0007]

Therefore, according to the present invention, a DC power source is provided through a common emergency stop button for emergency stop of the operation of a fluid actuator for a plurality of solenoid coils having different rated currents and one end of an electromagnetic relay. The solenoid coil is connected to one pole and the other end is connected to the other pole of the DC power supply through the power amplification element that performs on / off operation, and the rated current is larger than the maximum rated current of the power amplification element. This series circuit is connected in parallel with the DC power supply and the series circuit of the emergency stop button, and the diode is connected in parallel with the coil of the solenoid in this series circuit in reverse polarity to the DC power supply.

[0008]

According to the structure of the present invention, the emergency stop button is operated while the exciting current is flowing to the coil of the solenoid having a rated current larger than the maximum rated current of the power amplification element, and the DC power is cut off from the coil. Then, a counter electromotive force is induced from the coil at this moment. The impulse current based on this counter electromotive force circulates in the closed circuit composed of the coil and the diode connected in parallel with the coil, and is absorbed, so that another solenoid is excited by the impulse current after the operation of the emergency stop button. As a result, the malfunction of the fluid actuator can be prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a controller, which is provided so as to output a signal for exciting a solenoid from ports A, 2A, 2B, ports B, 3A, 3B, ports C, 4A, 4B according to a preprogrammed procedure. . 5A,
5B and 5C are field effect transistors as power amplification elements, each having a gate terminal 6A, 6B, 6C, a drain terminal 7A, 7B, 7C, a source terminal 8A, 8B, 8C, and a field effect transistor 5A, Gate terminal 6A
Via the photo coupler to the ports A, 2A, 2 of the controller 1.
B, the drain terminal 7A is connected to the output terminal 9A, and the source terminal 8A is connected to each of the field effect transistors 5A, 5A.
A signal for exciting the solenoid output from the ports A, 2A, 2B of the controller 1 is input to the gate terminal 6A through the photocoupler, which is connected to the power supply terminal 11 via the power supply line 10 common to B and 5C. The solenoid is turned on and the exciting current of the solenoid is supplied from the drain terminal 7A to the source terminal 8A. In addition, the field effect transistor 5B
Then, the gate terminal 6B is connected to the controller 1 via the photo coupler.
, The drain terminal 7B is connected to the output terminal 9B, and the source terminal 8B is connected to the power supply terminal 11 through the power supply line 10 common to the field effect transistors 5A, 5B, and 5C. , Port B of controller 1, 3A,
The signal for exciting the solenoid output from 3B is input to the gate terminal 6B via the photocoupler to be turned on,
The exciting current of the solenoid is provided so as to pass from the drain terminal 7B to the source terminal 8B. Further, in the field effect transistor 5C, the gate terminal 6C is connected to the ports C, 4A, and 4B of the controller 1 through the photocoupler, the drain terminal 7C is connected to the output terminal 9C, and the source terminal 8C is connected to each field effect transistor. 5A, 5B, and 5C are connected to a power supply terminal 11 through a common power supply line 10, and a signal for exciting a solenoid output from ports C, 4A, and 4B of the controller 1 is supplied to a gate terminal 6C via a photocoupler.
It is provided so that the solenoid is energized to be turned on and the exciting current of the solenoid is supplied from the drain terminal 7C to the source terminal 8C. The field effect transistors 5A, 5B,
In 5C, the maximum value of the current flowing from the drain terminals 7A, 7B, 7C toward the source terminals 8A, 8B, 8C is the maximum rated current.

Reference numerals 12A, 12B and 12C are protection circuits for protecting the field effect transistors 5A, 5B and 5C and have the same structure. In the protection circuit 12A, the drain terminal 7A and the source terminal 8A of the field effect transistor 5A are connected. A diode 13A and a Zener diode 14A are connected in series between the flywheel diode 1 and the series circuit.
5A are connected in parallel to form a closed circuit with the diode 13A, the Zener diode 14A and the flywheel diode 15A, and the overvoltage applied to the drain terminal 7A of the field effect transistor 5A is applied to the Zener diode 14A.
The current is circulated and absorbed in the closed circuit so that the Zener voltage of A is obtained. Further, in the protection circuit 12B, a diode 13B and a Zener diode 14B are connected in series between the drain terminal 7B and the source terminal 8B of the field effect transistor 5B, and the flywheel diode 15B is connected in parallel to this series circuit. Thirteen
B, the Zener diode 14B and the flywheel diode 15B form a closed circuit, and the current is circulated and absorbed in the closed circuit so that the overvoltage applied to the drain terminal 7B of the field effect transistor 5B becomes the Zener voltage of the Zener diode. It is provided. Furthermore, the protection circuit 12C
Then, the diode 13C and the Zener diode 14C are connected in series between the drain terminal 7C and the source terminal 8C of the field effect transistor 5C, the flywheel diode 15C is connected in parallel to this series circuit, and the diode 13C and the Zener diode 14C are connected. The flywheel diode 15C and the flywheel diode 15C form a closed circuit, and the current is circulated and absorbed in the closed circuit so that the overvoltage applied to the drain terminal 7C of the field effect transistor 5C becomes the Zener voltage of the Zener diode. The controller 1, the field effect transistors 5A, 5B and 5C, and the protection circuits 12A, 12B and 12C constitute a programmable controller 16. F is a fuse connected to the power supply line 10.

Reference numeral 17 denotes an electromagnetic relay, one end of which is connected to the output terminal 9A of the programmable controller 16 and the other end of which is connected to the positive electrode of the DC power source 19 through an emergency stop button 18 having a normally closed contact, and a field effect transistor. When the 5A is turned on, the exciting current supplied from the DC power supply 19 is supplied to close the normally open contact 21 inside. 20A and 20B are solenoid coils, one end of each of which is connected to the output terminals 9B and 9C of the programmable controller 16 and the other end of which is connected to the positive electrode of the DC power supply 19 through the emergency stop button 18, and the field effect transistor 5B. It is provided so that the exciting current supplied from the DC power supply 19 is passed by the ON operation of 5C. The solenoid is excited by this exciting current to control the switching of the electromagnetic switching valve to drive the fluid actuator. When the emergency stop button 18 is pressed,
The exciting current supplied from the DC power supply 19 to the electromagnetic relay 17 and the solenoid coils 20A and 20B is cut off. The negative electrode of the DC power supply 19 is connected to the power supply terminal 11 of the programmable controller 16 and is electrically connected to the common power supply line 10. Further, the exciting current flowing through the coils 20A and 20B of the solenoid is the rated current of each coil, and the field effect transistor 5A,
It is set smaller than the maximum rated current of 5B and 5C.

20C is a field effect transistor 5A, 5
A solenoid coil having a rated current larger than the maximum rated current of B and 5C, which is connected in series with the normally open contact 21 inside the electromagnetic relay 17, and is composed of a DC power supply 19 and an emergency stop button 18. It is connected in parallel with the circuit. Reference numeral 22 denotes a diode, which is connected in parallel with the solenoid coil 20C and has a reverse polarity to the DC power source 19, and an impulse current based on the counter electromotive force induced in the solenoid coil 20C when the emergency stop button 18 is pressed is applied to the solenoid. The coil 20C and the diode 21 are provided so as to circulate and absorb them in a closed circuit.

Next, the operation of this structure will be described. When a signal for exciting the solenoid is output from the ports B, 3A, 3B of the controller 1 according to a pre-programmed procedure, the field effect transistor 5B inputs this signal to the gate terminal 6B via the photo coupler and turns on. Operate. At this time, the DC power supply 19 is connected to the solenoid coil 20.
An exciting current corresponding to the rated current of A is applied to the solenoid coil 2
Supply to 0A. The solenoid that is excited by this exciting current controls the switching of the electromagnetic switching valve to drive the fluid actuator.

When the signals output from the ports B, 3A and 3B are turned off, the field effect transistor 5B is turned off and the exciting current supplied from the DC power supply 19 to the solenoid coil 20A is cut off. At that moment, an impulse current based on the back electromotive force induced by the solenoid coil 20A flows from the solenoid coil 20A toward the output terminal 9B. This impulse current flows from the diode 13B of the protection circuit 12A, and the Zener diode 14B and the flywheel diode 15 are arranged so that the voltage applied to the drain terminal 7B of the field effect transistor 5B becomes the Zener voltage of the Zener diode 14B.
It is absorbed by circulating in a closed circuit consisting of B. in this way,
The protection circuit 12B controls the solenoid coil 20 at the moment when the exciting current passing through the solenoid coil 20A is cut off.
The field effect transistor 20 is generated from the counter electromotive force induced by A
Protects A.

Also, when signals for exciting the solenoids are output from the ports C, 4A, 4B of the controller 1, the field effect transistor 5C is output in the same manner as when the signals are output to the ports B, 3A, 3B. Is turned on, an exciting current corresponding to the rated current of the solenoid coil 20B is supplied from the DC power supply 19, and the solenoid excited by the exciting current switches and controls the electromagnetic switching valve to drive the fluid actuator. And ports C, 4A, 4B
When the output signal is turned off, the solenoid coil 2
An impulse current based on the counter electromotive force induced by 0B is circulated in the protection circuit 12C to protect the field effect transistor 5C from the counter electromotive force induced by the coil 20B of the solenoid.

When a signal for exciting the solenoid is output from the ports A, 2A, 2B of the controller 1, the field effect transistor 5A inputs this signal to the gate terminal 6A via the photocoupler and turns on. At this time, DC power supply 1
9 energizes the electromagnetic relay with exciting current. Therefore, the normally open contact 21 inside the electromagnetic relay 17 is closed, and the exciting current according to the rated current of the solenoid coil 20C is supplied from the DC power source 19 to the solenoid coil 20C via the closed contact of the emergency stop button 18. The solenoid that is supplied and excited by this exciting current switches the electromagnetic switching valve to control the fluid actuator.

Then, the ports A, 2A and 2B of the controller 1
When the output signal is turned off, the electromagnetic relay 17 is turned off, the exciting current that has been supplied to the electromagnetic relay 17 from the DC power supply 19 is cut off, and the contact 21 of the electromagnetic relay 17 opens after the response delay time has elapsed. . Therefore, the exciting current supplied from the DC power supply 19 to the solenoid coil 20C through the closed contact of the emergency stop button 18 is cut off. The impulse current based on the counter electromotive force induced by the coil 20C of the solenoid at the moment when the exciting current supplied to the coil 20C of the solenoid is cut off, because the normally open point 21 of the electromagnetic relay 17 is already open. Does not energize the other solenoid coils 20A and 20B that have flown into the power supply terminal 11 and are demagnetized, and the solenoid coil 20C and this coil 20C
And a diode connected in parallel with the diode are circulated in the forward direction of the diode and absorbed.

Further, while the field effect transistor 5A is turned on and the fluid actuator is driven by the exciting current supplied to the solenoid coil 20C, an uncontrollable abnormality such as runaway or malfunction occurs in the fluid actuator. When the emergency stop button 18 is pressed in order to make an emergency stop of the fluid actuator, the coil 20C of the solenoid in which the exciting current is energized induces a counter electromotive force at the moment when the DC power source 19 is cut off by the operation of the emergency stop button 18. To do.
The impulse current based on the counter electromotive force is circulated and absorbed in the forward direction of the diode by the closed circuit composed of the coil 20C of the solenoid and the diode 22 connected in parallel with the coil 20C. Even if the exciting current to the electromagnetic relay 17 is cut off by the operation and the normally open contact 21 of the electromagnetic relay 17 is closed due to the response delay time, the impulse current does not flow toward the power supply terminal 11 and the fluid actuator operates. It is possible to prevent a malfunction that occurs.

Further, since the diode 22 is connected in parallel with the coil 20C having a rated current larger than the maximum rated current of the field effect transistors 5A, 5B, 5C, no special device is required and the cost is extremely low. Thus, it is possible to prevent a malfunction occurring in the fluid actuator when the emergency stop button 18 is operated.

It should be noted that, when the electromagnetic relay 17 is demagnetized, the impulse current based on the counter electromotive force induced by the electromagnetic relay 17 is circulated and absorbed by the protection circuit 12A, and the counter electromotive force induced by the electromagnetic relay 17 causes the electric field effect. Transistor 5
Protects A.

[0021]

As described above, according to the present invention, one of the DC power sources is connected to the coils of the plurality of solenoids having different rated currents and one end of the electromagnetic relay via the common emergency stop button for emergency stop of the operation of the fluid actuator. Connected to the other pole of the DC power supply through the power amplification element that performs on / off operation and connects the other end of the solenoid coil to the electromagnetic relay whose rated current is greater than the maximum rated current of the power amplification element. This series circuit was connected in series with the open contact, and this series circuit was connected in parallel with the series circuit of the DC power supply and the emergency stop button, and the diode was connected in parallel with the coil of the solenoid in this series circuit in reverse polarity to the DC power supply. It is possible to prevent a malfunction that occurs in the actuator when it is operated. Since the diode was connected in reverse polarity to the DC power supply in parallel with the solenoid coil whose rated current was higher than the maximum rated current of the power amplification element, no special device was required and the emergency stop button was operated at extremely low cost. It is possible to prevent malfunction that sometimes occurs in the fluid actuator.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a solenoid excitation circuit showing an embodiment of the present invention.

FIG. 2 is an electric circuit diagram of a conventional solenoid excitation circuit.

[Explanation of symbols]

 5A, 5B, 5C power amplification element 10 power supply line 17 electromagnetic relay 18 emergency stop button 19 DC power supply 20A, 20B, 20C coil 21 normally open contact 22 diode

Claims (1)

[Claims] 1. A plurality of solenoid coils having different rated currents and one end of an electromagnetic relay are connected to one pole of a DC power source and the other end is connected through a common emergency stop button for emergency stop of operation of a fluid actuator. Connect to the other pole of the DC power supply via the power amplification element that performs on / off operation, and connect the solenoid coil whose rated current is larger than the maximum rated current of the power amplification element in series with the normally open contact of the electromagnetic relay. A solenoid exciter circuit characterized in that a circuit is connected in parallel with a series circuit of a DC power supply and an emergency stop button, and a diode is connected in parallel with a coil of a solenoid in the series circuit in a polarity opposite to that of the DC power supply.