JP3323314B2 - Solenoid excitation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, there is a solenoid excitation circuit of this type shown in FIG. This includes a controller 30 for outputting a signal for exciting the solenoid in accordance with a previously programmed procedure, and a field effect transistor 31A as a power amplifying element for inputting the signal output from the controller 30 and performing on / off operation. 31B, 31C
And these field effect transistors 31A, 31B, 31
A plurality of output terminals 33A, 33B, 33C connected to the drain terminals 32A, 32B, 32C of C, and a power terminal 36 connected to the source terminals 34A, 34B, 34C via a common power line 35. A controller 37, and each of the output terminals 33A, 33B, 33C of the programmable controller 37 is connected to a plurality of solenoid coils 38A, 38 having different rated currents.
B, 38C, and the other ends of these solenoid coils 38A, 38B, 38C are connected to the positive electrode of a DC power supply 40 via an emergency stop button 39 having a normally closed contact. When connected to the power supply terminal 36, the field effect transistors 31A, 31B, 31C are turned on to supply an exciting current corresponding to the rated current to the corresponding solenoid coil from the DC power supply 40, and electromagnetically switched by the solenoid excited by the exciting current. The fluid actuator is driven by switching control of the valve.
41A, 41B and 41C are flywheel diodes constituting a protection circuit, and 42 is a fuse.

However, in this case, the output terminals 33A, 3A
Solenoid coils 38A, 3C connected to 3B, 33C
Since the rated currents of the 8B and 38C have various sizes, the output terminals 33A, 33B and 33C are erroneously connected to a solenoid coil having a rated current greater than the maximum rated current of the field effect transistors 31A, 31B and 31C. In this case, only the current specified by the maximum rated current can flow through the coil of the solenoid, so that the solenoid is not sufficiently excited, so that a problem occurs in that the solenoid-operated switching valve causes a switching operation failure. For this reason, the applicant replaces the solenoid coil 38A, for example, in which the rated current of the solenoid coil is designed to be equal to or greater 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 is connected in series with a normally open contact of this electromagnetic relay and a coil 38A of a solenoid.
0 and the emergency stop button 39 are connected in parallel to a series circuit, and the electromagnetic relay is excited by turning on the field effect transistor 31A to close the normally open contact of the 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 case, an uncontrollable abnormality such as runaway or malfunction occurs in the fluid actuator while the field-effect transistor 31A is on, and an attempt is made to stop the fluid actuator urgently. When the emergency stop button 39 is pressed, the solenoid coil 38A in which the exciting current is being conducted induces a counter electromotive force at the moment when the emergency stop button 39 is operated to cut off the DC power supply 40. Also, even if the electromagnetic relay is demagnetized by turning off the field effect transistor 31A by operating the emergency stop button 39, there is a response delay time when the normally open contact shifts from the closed state to the open state due to a mechanical response delay. are doing. Therefore, an impulse current having a waveform which rises rapidly based on the back electromotive force and then attenuates flows from the solenoid coil 38A to the power supply terminal 36 of the programmable controller 37. This impulse current is supplied to the field effect transistors 31B and 31C via the common power supply line 35.
The flywheel diodes 41B and 41C are energized from the source terminals 34B and 34C, 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.

[0005] Therefore, when an uncontrollable abnormality such as runaway or malfunction occurs in the fluid actuator, even if the emergency operation of the fluid actuator is attempted by operating the emergency stop button 35, the operating fluid actuator is immediately stopped. The solenoid valve does not operate, or activates the stopped fluid actuator while the impulse current is attenuated.In addition, if the solenoid switching valve has a detent mechanism, the impulse current flows through the solenoid coil. If the electromagnetic switching valve is switched during this time, the switched state is maintained, and a new malfunction is induced in the fluid actuator switched and controlled by the electromagnetic switching valve.

The present invention solves such a problem.
When the fluid actuator is driven by exciting each of a plurality of solenoids having different rated currents with a power amplifying element connected to a common DC power supply, it is possible to prevent a malfunction occurring in the fluid actuator when the emergency stop button is operated. It is an object of the present invention to provide a solenoid excitation circuit.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a DC power supply via a common emergency stop button for urgently stopping the operation of a fluid actuator between one end of an electromagnetic relay and a plurality of solenoid coils having different rated currents. And the other end is connected to the other pole of the DC power supply via a power amplifying element that performs on / off operation, and a solenoid coil whose rated current is larger than the maximum rated current of the power amplifying element. The series circuit is connected in parallel with a normally open contact, and this series 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 the solenoid coil in this series circuit with the opposite polarity to the DC power supply.

[0008]

According to the configuration of the present invention, the emergency stop button is operated while the exciting current is applied to the solenoid coil having a rated current larger than the maximum rated current of the power amplifying 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 the back electromotive force is absorbed by circulating through a closed circuit composed of the coil and a diode connected in parallel with the coil, so that another solenoid is excited by the impulse current after the operation of the emergency stop button. Is prevented from occurring, and a malfunction that occurs in the fluid actuator can be prevented.

[0009]

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 to output a signal for exciting a solenoid from ports A, 2A, 2B, ports B, 3A, 3B, ports C, 4A, 4B in accordance with a pre-programmed procedure. . 5A,
Reference numerals 5B and 5C denote field effect transistors as power amplification elements, each having a gate terminal 6A, 6B, 6C, a drain terminal 7A, 7B, 7C, and a source terminal 8A, 8B, 8C. Gate terminal 6A
Are connected to the ports A, 2A, and 2 of the controller 1 through a photocoupler.
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.
B and 5C are connected to a power supply terminal 11 via a common power supply line 10, and a signal for exciting a solenoid output from ports A, 2A and 2B of the controller 1 is input to a gate terminal 6A via a photocoupler. To turn on, and to supply an exciting current of the solenoid from the drain terminal 7A to the source terminal 8A. The field effect transistor 5B
Then, the gate terminal 6B is connected to the controller 1 via a photocoupler.
, The drain terminal 7B is connected to the output terminal 9B, and the source terminal 8B is connected to the power supply terminal 11 via the power supply line 10 common to the field effect transistors 5A, 5B, and 5C. , Ports B and 3A of the controller 1,
A signal for exciting the solenoid output from 3B is input to the gate terminal 6B via the photocoupler and turned on,
An excitation current for the solenoid is provided to flow 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 via 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 via 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.
To turn on to input an exciting current of the solenoid from the drain terminal 7C to the source terminal 8C. Note that each of the field effect transistors 5A, 5B,
In 5C, the maximum value of the current flowing from the drain terminals 7A, 7B, 7C to the source terminals 8A, 8B, 8C is the maximum rated current.

Reference numerals 12A, 12B, and 12C denote protection circuits for protecting the field effect transistors 5A, 5B, and 5C, which have the same configuration. In the protection circuit 12A, the connection between the drain terminal 7A and the source terminal 8A of the field effect transistor 5A is established. A diode 13A and a Zener diode 14A are connected in series between the flywheel diode 1A and the flywheel diode 1A.
5A are connected in parallel, a closed circuit is formed by 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 reduced by the Zener diode 14A.
A current is circulated and absorbed in a closed circuit so as to have a Zener voltage of A. In the protection circuit 12B, a diode 13B and a Zener diode 14B are connected in series between a drain terminal 7B and a source terminal 8B of the field effect transistor 5B, and a flywheel diode 15B is connected in parallel to this series circuit. 13
B, a Zener diode 14B and a flywheel diode 15B form a closed circuit, and a 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. Provided. Further, the protection circuit 12C
Then, a diode 13C and a Zener diode 14C are connected in series between a drain terminal 7C and a source terminal 8C of the field effect transistor 5C, and a flywheel diode 15C is connected in parallel to this series circuit. A flywheel diode 15C and a flywheel diode 15C constitute a closed circuit, and the overcurrent applied to the drain terminal 7C of the field effect transistor 5C is provided so as to circulate and absorb the current in the closed circuit so as to become 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.

An electromagnetic relay 17 has one end connected to the output terminal 9A of the programmable controller 16 and the other end connected to the positive electrode of a DC power supply 19 via an emergency stop button 18 having a normally closed contact. The excitation current supplied from the DC power supply 19 is supplied by turning on the 5 A, and the normally open contact 21 provided inside is closed. Reference numerals 20A and 20B denote solenoid coils, one end of which is connected to the output terminals 9B and 9C of the programmable controller 16 respectively, and the other end of which is connected to the positive electrode of the DC power source 19 via the emergency stop button 18 and the field effect transistor 5B. 5C, the excitation current supplied from the DC power supply 19 is supplied by the ON operation of 5C. The solenoid actuator that is excited by the exciting current controls the switching of the electromagnetic switching valve to drive the fluid actuator. When the emergency stop button 18 is pressed,
An exciting current supplied from the DC power supply 19 to the electromagnetic relay 17 and the solenoid coils 20A and 20B is provided to be 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 provided smaller than the maximum rated current of 5B, 5C.

20C is a field effect transistor 5A, 5C
B, 5C, a solenoid coil having a rated current larger than the maximum rated current, connected in series with a normally open contact 21 provided inside an electromagnetic relay 17, and configured in series with a DC power supply 19 and an emergency stop button 18. Connected in parallel with the circuit. Reference numeral 22 denotes a diode which is connected in parallel with the solenoid coil 20C and in the opposite polarity to the DC power supply 19, and outputs an impulse current based on the back electromotive force induced in the solenoid coil 20C when the emergency stop button 18 is pressed. It is provided so as to be circulated and absorbed in a closed circuit composed of the coil 20C and the diode 21.

Next, the operation of the above configuration will be described. When a signal for exciting the solenoid is output from the ports B, 3A, and 3B of the controller 1 according to a previously programmed procedure, the field-effect transistor 5B inputs this signal to the gate terminal 6B via the photocoupler 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 fluid actuator is driven by switching control of the electromagnetic switching valve by the solenoid excited by the exciting current.

When the signals output from the ports B, 3A, 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 from the solenoid coil 20A flows from the solenoid coil 20A to the output terminal 9B. This impulse current flows in from the diode 13B of the protection circuit 12A, and the Zener diode 14B and the flywheel diode 15 are arranged such 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 circulated through a closed circuit consisting of B and absorbed. in this way,
The protection circuit 12B activates the solenoid coil 20A at the moment when the exciting current supplied to the solenoid coil 20A is interrupted.
A from the back electromotive force induced from A
A is protected.

When a signal for exciting the solenoid is output from ports C, 4A and 4B of the controller 1, similarly to the case where this signal is output to ports B, 3A and 3B, the field effect transistor 5C 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 that is 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
The impulse current based on the back electromotive force induced from OB is circulated by the protection circuit 12C to protect the field effect transistor 5C from the back electromotive force induced from the solenoid coil 20B.

When a signal for exciting the solenoid is output from the ports A, 2A and 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, the DC power supply 1
Numeral 9 supplies an exciting current to the electromagnetic relay. Therefore, the normally open contact 21 inside the electromagnetic relay 17 is closed, and the exciting current corresponding to the rated current of the solenoid coil 20C is supplied from the DC power supply 19 to the solenoid coil 20C via the closed contact of the emergency stop button 18. The electromagnetic actuator is driven by switching control of the electromagnetic switching valve by a solenoid that is supplied and excited by the excitation current.

The ports A, 2A, 2B of the controller 1
When the output signal is turned off, the electromagnetic relay 17 is turned off, the exciting current flowing from the DC power supply 19 to the electromagnetic relay 17 is cut off, and the contact 21 of the electromagnetic relay 17 is opened after a response delay time has elapsed. . Therefore, the exciting current supplied from the DC power supply 19 to the solenoid coil 20C via the closed contact of the emergency stop button 18 is cut off. The impulse current based on the back electromotive force induced from the solenoid coil 20C at the moment when the exciting current supplied to the solenoid coil 20C is cut off, because the normally open point 21 of the electromagnetic relay 17 is already open. The coils 20A and 20B of the other solenoids which flow into the power supply terminal 11 and are demagnetized are not excited, and the coil 20C of the solenoid and this coil 20C are not excited.
And a diode connected in parallel, and is absorbed by circulating in a forward direction of the diode.

Further, when 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 to make an emergency stop of the fluid actuator, the solenoid coil 20C in which the exciting current is being supplied induces a back electromotive force at the moment when the emergency stop button 18 is operated and the DC power supply 19 is cut off. I do.
The impulse current based on the back electromotive force is absorbed by circulating in a forward direction of the diode a closed circuit formed by a solenoid coil 20C and a diode 22 connected in parallel with the coil 20C. The impulse current does not flow toward the power supply terminal 11 even when the exciting current to the electromagnetic relay 17 is interrupted by the operation and the normally open contact 21 of the electromagnetic relay 17 is closed due to the response delay time. The malfunction that occurs can be prevented.

Further, since the diode 22 has a simple configuration in which 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, and 5C, no special device is required and the cost is extremely low. Thus, it is possible to prevent a malfunction that occurs in the fluid actuator when the emergency stop button 18 is operated.

When the electromagnetic relay 17 is demagnetized, the protection circuit 12A circulates and absorbs the impulse current based on the back electromotive force induced by the electromagnetic relay 17 when the electromagnetic relay 17 is demagnetized. Transistor 5
A is protected.

[0021]

As described above, according to the present invention, one end of the DC power supply is connected to one end of the solenoid coil and one end of the electromagnetic relay via the common emergency stop button for urgently stopping the operation of the fluid actuator. And the other end is connected to the other pole of the DC power supply via a power amplification element that performs on / off operation, and the solenoid coil whose rated current is larger than the maximum rated current of the power amplification element is always connected to the electromagnetic relay. This series circuit was connected in parallel with the series circuit of the DC power supply and the emergency stop button by connecting in series with the open contact, and a diode was connected in parallel with the solenoid coil in this series circuit in reverse polarity to the DC power supply. A malfunction that occurs in the actuator when operated can be prevented. And, because the diode was connected in reverse polarity to the DC power supply in parallel with the solenoid coil whose rated current is larger than the maximum rated current of the power amplification element, the emergency stop button was operated at extremely low cost without requiring any special equipment. A malfunction that sometimes occurs in the fluid actuator can be prevented.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of a solenoid excitation circuit showing one 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 line 17 Electromagnetic relay 18 Emergency stop button 19 DC power supply 20A, 20B, 20C coil 21 Normally open contact 22 Diode

Claims (1)

(57) [Claims] 1. A coil of a plurality of solenoids having different rated currents and one end of an electromagnetic relay are connected to one pole of a DC power supply via a common emergency stop button for urgently stopping the operation of a fluid actuator, and the other end is connected. Connected to the other pole of the DC power supply via the power amplifying element that performs on / off operation, a solenoid coil whose rated current is larger than the maximum rated current of the power amplifying element is connected in series with the normally open contact of the electromagnetic relay, and this series A solenoid excitation circuit comprising: a circuit connected in parallel with a series circuit of a DC power supply and an emergency stop button; and a diode connected in parallel with the solenoid coil in the series circuit with a polarity opposite to that of the DC power supply.