JPH0124690Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive circuit for a safety terminal such as an emergency gas cutoff valve, and more particularly to a drive circuit having a function of displaying the operating status of the terminal and a line break.

Conventionally, there is a drive circuit of this type as shown in FIG. This drive circuit includes a drive coil 11 that drives a terminal device 1 such as an emergency gas cutoff valve, for example.
, a changeover switch 12 that changes according to the operating state of the terminal 1, and a one-shot circuit (not shown).
It consists of a starting circuit 31 having a contact point K, and a starting device 3 having first and second display circuits 32 and 33 having indicator lights L ₁ and L ₂ made of light emitting diodes. 12
are connected to the lines 2 drawn out from the starting device 3, respectively.

In this conventional drive circuit, indicator lights L ₁ and L ₂ are connected to the first and second contacts of the changeover switch 12 in correspondence to form first and second display circuits 32 and 33. , When the changeover switch 12 is switched in response to the operating state of the terminal device 1, for example, the opening and closing of a valve, the indicator lights L ₁ and L ₂ are selectively turned on in response to display the operating state of the terminal device 1. be done.

However, in this conventional device, as shown in FIG. 1, the drive coil 11 and the changeover switch 12 are connected by separate lines 2, so five lines are required. Therefore, there are disadvantages in that a large amount of wire is required, the wiring space is large, and the wiring work is time-consuming.

In addition, in this conventional system, even if a disconnection accident such as disconnection or poor contact occurs on each line, especially on the line 2 of the drive coil 11, the accident cannot be displayed, so the terminal device cannot be driven when necessary. There is danger. On the other hand, there is a drawback that it takes time and effort for maintenance to discover this disconnection.

This invention was made in view of these points,
The terminal device and the starting device are connected by a pair of tracks, and the pair of tracks not only drives the terminal device but also enables display of its operating status, which greatly reduces the amount of track wire and wiring space, and also reduces the amount of wiring required. Wiring work can be made easier, and by providing a disconnection indicator circuit,
To provide a terminal device drive circuit for safety, which can easily discover a line break, facilitate maintenance work, and prevent an accident in which the terminal device cannot be driven.

That is, the present invention connects in series a limit switch that opens and closes in response to the operating state of the terminal and a high-resistance terminating resistor connected in parallel to a drive coil that drives a security terminal. forming a terminal circuit, the terminal circuit being connected in series to a pair of lines drawn out from the starting device, and a starting circuit supplying a pulsed drive current to the drive coil; first and second indicator lights that supply a monitoring current and turn on or off the first and second indicator lights in response to changes in the level of the monitoring current caused by opening and closing of the limit switch to indicate the operating state of the terminal; and a disconnection indicator circuit that supplies a disconnection monitoring current to the terminal circuit and lights up a third indicator light to indicate a disconnection in response to interruption of the monitoring current due to a disconnection of the line. It consists of

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 2 is a circuit diagram showing an embodiment of the security terminal drive circuit of the present invention. The drive circuit of the present invention shown in the figure comprises a starting device 3 and a terminal device 1 connected to a pair of lines 2 drawn out from the starting device 3. The starting device 3 includes a starting circuit 34, a first The terminal device 1 includes two operation display circuits 35 and 36 and a disconnection display circuit 37, and also includes a terminal circuit 10.

The terminal circuit 10 includes a drive coil 11 that drives a security terminal, a limit switch 13 that opens and closes in response to the operating state of the terminal, and a high-resistance terminating resistor RE connected in parallel. A line 2 formed as follows and drawn out from the starting device 3
connected in series. The drive coil 11 is a coil that constitutes a solenoid, for example, and opens and closes a valve, etc. by passing a pulse current through it and energizing it. Therefore, the terminal device may be anything operated by such a coil, and includes, for example, an emergency gas cutoff valve, a smoke exhaust damper, a fire door release, and the like. The limit switch 13 is normally closed in this embodiment, and is linked to a terminal device, such as an emergency gas cutoff valve, so that it opens when the terminal device, for example, the emergency gas cutoff valve is closed. The terminating resistor RE is used to cause a disconnection monitoring current to flow when the limit switch 13 is opened. However, the resistance value of this resistor RE is set in a range in which the first indicator light _L1 of the first operation indicator circuit 35, which will be described later, does not light up and, on the other hand, the disconnection indicator circuit 37 does not operate.

The starting circuit 34 includes a one-shot circuit 341 that outputs a pulse signal, a starting switch 342 that starts the one-shot circuit 341, and a contact _K1 that is closed by the pulse of the one-shot circuit ₃₄₁ . By closing, a terminal circuit 10, which will be described later, is directly connected to a power source and a pulsed current is supplied. In this embodiment, the first and second operation display circuits 35 and 36 are provided with a contact _K2 .
This contact _K2 opens and closes in conjunction with the above contact _K1 ,
When the pulse current is supplied to the terminal circuit 10, the indicator light of the first operation indicator circuit 35 is turned off;
This prevents the disconnection display circuit 37 from operating temporarily. Therefore, the contact _K2 may be omitted if these can be ignored.

The first operation indicator circuit 35 is configured by connecting a first indicator light L ₁ made of a light emitting diode or the like in series with the line 2 and the terminal circuit 10 via a resistor R ₁ and a diode D ₁ . indicator light L ₁ , resistor R ₁ ,
It is turned on by an operation monitoring current flowing through the diode D ₁ , the line 2, and the drive coil 11 and limit switch 13 in the terminal circuit 10. Note that when the limit switch 13 is open, the level of the monitoring current becomes low as described above, and the indicator light L ₁
does not light up.

On the other hand, the second operation indicator circuit 36 is configured by connecting a second indicator light L ₂ made of a light emitting diode or the like to switching transistors Q ₃ and Q ₄ in series, and both transistors Q ₃ and Q ₄ When both are turned on, they are connected to the power line and light up. The transistor _Q3 is turned on and off by a transistor _Q2 which has a Zener diode Z connected to its base to form a level detection circuit. This Zener diode Z has its anode side voltage divided by resistors R ₆ and R ₇ and is connected to the diode D ₁ , and detects the level change of the operation monitoring current caused by opening and closing of the limit switch 13 . That is, when the limit switch 13 is closed, it becomes conductive, and when it is opened, it becomes non-conductive, turning the transistor _Q2 on and off. On the other hand, the transistor _Q4 is controlled to be turned on and off by a switching transistor _Q1 of a disconnection indicating circuit 37, which will be described later, so that the indicator lamp _L2 will not light up when the line 2 is disconnected. Therefore, the second display circuit L ₂
When the third indicator light L ₃ of the disconnection indicator circuit 37 is turned on at the same time, the transistor Q ₄ may be omitted.

The disconnection indicator circuit 37 is constructed by connecting a third indicator light L ₃ made of a light emitting diode or the like to an indicator light drive circuit IC made of an inverter or _the like.
Lights up when the output of the driver circuit IC becomes low level.
The output level of this drive circuit IC is set by a switching transistor _Q1 that is turned on and off depending on whether a base current serving as a disconnection monitoring current is above a certain level. That is, resistors R ₂ and R ₃ are diode D ₁
is connected in series to the line 2 and the terminal circuit 10 via the line 2, and if the disconnection monitoring current flowing through this circuit is less than a certain level due to line 2 interruption, poor contact, etc.
Transistor _Q1 is turned off. Note that the current level at which the switch is turned off is set smaller than the current that can flow through the termination resistor RE.

Next, the operation of the security terminal drive circuit of the present invention will be explained. In addition, here, the case where an emergency gas cutoff valve is used as a terminal device will be explained as an example.

First, under normal conditions, the emergency gas cutoff valve is open, and the limit switch 13 linked to this valve is closed. In such a state, the operation monitoring current flows from the power line + side to the first indicator light L ₁ ,
It reaches one side of the power supply line through the resistor R ₁ , diode D ₁ , line 2, drive coil 11, limit switch 13 and line 2. This lights up the indicator light _L1 , indicating that the emergency gas cutoff valve is open. Note that the drive coil 11 is set so that it does not operate unless the current is larger than this monitoring current.

Also, in this state, the second display circuit 36
Since the Zener diode Z becomes conductive, the switching transistor _Q2 is turned on, and therefore the transistor _Q3 is turned off. Therefore, the second indicator light _L2 does not light up. On the other hand, in the disconnection display circuit 37, the base current of the transistor _Q1 is
The current flows through the resistor R ₃ to the diode D ₁ in the same path as above, and the transistor Q ₁ is turned on. Therefore, the output of the indicator lamp drive circuit IC whose input level is set by the collector voltage of the transistor _Q1 becomes the same high level as the input, and the third indicator lamp _L3 does not light up.

Next, when the starting switch 342 of the starting circuit 34 is turned on, the one-shot circuit 341 operates to generate a pulse and close the contacts _K1 and _K2 . This connects the terminal circuit 10 directly to the power supply line via the contact _K1 , and a large pulsed current flows through the drive coil 11, activating the emergency gas cutoff valve and closing it. At the same time, the limit switch 13 opens.

In this state, the operation monitoring current flowing through the first indicator light L ₁ is reduced to a low level by the terminating resistor RE, so that the indicator light L ₁ is turned off. on the other hand,
The anode potential of Zener diode Z increases,
Since the diode Z becomes non-conductive, the transistor _Q2 is turned off. Therefore, the transistor
_Q3 is turned on as the base current flows through resistors _R9 and _R10 . At this time, transistor Q ₁ is
Even though the current flows through the high-resistance termination resistor RE, it is in the on state, so the transistor _Q4 is also in the on state. As a result, the second indicator light _L2 lights up, indicating that the emergency gas cutoff valve is closed. In this case, the disconnection indicator circuit 37 does not operate, and therefore the third indicator light _L3 does not light up.

Next, if the line 2 is disconnected, the operation monitoring current does not flow, so the first indicator light is off. Also, the transistor _Q1 of the disconnection indicator circuit 37 is turned off to detect the disconnection, and the indicator light drive circuit IC
The output becomes low level like the input, and the third indicator light _L3 is turned on to indicate a disconnection. on the other hand,
In the second display circuit 36, a transistor
When Q ₂ turns off, transistor Q ₃ turns on, but
Transistor by turning off the above transistor _Q1
Since Q ₄ is off, indicator light L ₂ does not light up, therefore,
Only broken wires are displayed.

As explained above, the present invention connects a security terminal and a starting device with a pair of lines, drives the terminal by the pair of lines, and also operates a limit switch that opens and closes in response to the operating state of the terminal. By changing the level of the operation monitoring current flowing through the pair of lines, and displaying the operating status of the terminal device accordingly, there is no need to provide a separate line for monitoring, and the line material and This has the effect of greatly reducing the wiring space and making the wiring work easier. In addition, a high-resistance terminating resistor is provided in parallel with the limit switch, and a disconnection indicating circuit is provided in the starting device, making it easy to discover line disconnections, facilitating maintenance and inspection, and This has the effect of preventing drivability accidents.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a conventional security terminal driving circuit, and FIG. 2 is a circuit diagram showing an embodiment of the security terminal driving circuit of the present invention. 1... Terminal device, 10... Terminal circuit, 11... Drive coil, 14... Limit switch, 2... Line, 3... Starting device, 31, 34... Starting circuit,
32, 35...first operation display circuit, 33, 36
...Second indicator circuit, 34, 37...Disconnection indicator circuit, RE...Terminal resistor, L ₁ ...First indicator light, L ₂
...Second indicator light, L ₃ ...Third indicator light, Q ₁ ~
Q ₄ ...transistor, K, K ₁ , K ₂ ... contact.

Claims (1)

[Claim for Utility Model Registration] A limit switch that opens and closes in response to the operating state of the terminal and a high-resistance terminating resistor are connected in series to a drive coil that drives a security terminal. forming a terminal circuit; the terminal circuit;
A starting circuit is connected in series to a pair of lines drawn out from the starting device, and supplies a pulsed driving current to the driving coil; and a starting circuit supplies an operation monitoring current to the terminal circuit, and is connected in series to a pair of lines drawn out from the starting device, and is connected to first and second operation display circuits that turn on or off the first and second indicator lights in response to the level change of the monitoring current that occurs to indicate the operating state of the terminal; supplying a disconnection monitoring current, and in response to interruption of the monitoring current due to a disconnection of the line, a third
A security terminal drive circuit characterized in that the activation device is provided with a disconnection display circuit that lights up an indicator light to indicate a disconnection.