JPH0332383Y2 - - Google Patents

Description

[Detailed Description of the Invention] a. Field of Industrial Application The present invention relates to an automatic fire extinguishing system in which a fire extinguishing agent injection valve of a fire extinguisher is operated by a plunger solenoid.

b. Prior Art As is well known, electric discharge machines, machining centers, etc. are usually equipped with automatic fire extinguishing devices.
In the conventional automatic fire extinguishing system, as shown in FIG. The fire extinguishing agent injection valve (not shown) is opened and closed by pulling it.

The driving force for opening and closing the valve is normally about 50 kg, and the current necessary to generate this level of suction torque is continuously passed through the solenoid coil from the time the plunger solenoid is started.

c Problems to be solved by the invention Therefore, in conventional automatic fire extinguishing systems, the relatively large current that flows through the solenoid coil when the valve is driven continues to flow even after the plunger has completed its forward movement (after the valve has opened). , the solenoid coil may overheat. For this reason, attempts have been made to solve the above-mentioned problems by using a large plunger solenoid, but in this case, there are problems in that the device becomes larger and the cost increases.

The present invention was made to solve these problems, and its purpose is to provide an automatic fire extinguishing system that is small, inexpensive, and highly reliable.

d Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides an automatic fire extinguishing system in which the fire extinguishing agent injection valve of the fire extinguisher is operated by a plunger solenoid. For a short time from the start of the solenoid coil, the driving current necessary to attract the plunger to the forward position is passed through the solenoid coil to generate a large torque, and after that period, a current smaller than the driving current is applied to the solenoid coil. The plunger is held in the forward movement position with a small torque by flowing the current through the coil.

e Example The following is an example of the implementation of the present invention in Figures 1 and 2.
This will be explained with reference to the figures.

FIG. 1 shows an automatic fire extinguishing system 10 according to the present invention, in which a plunger solenoid 12, which has a plunger 12a movably arranged in the center of a solenoid coil, is integrated in the upper part of a fire extinguisher 11. installed. That is, a pair of support members 13a, 13b are screwed to the upper end of the extinguisher 11, and the plunger solenoid 12 is attached to the support members 13a, 13b by screws or the like. The lower end of the plunger 12a is arranged so as to be able to engage with the valve opening/closing main shaft 14 protruding from the upper end surface of the extinguisher 11, and when the main shaft 14 is pushed downward by the plunger 12a, A fire extinguishing agent injection valve (not shown) is opened and closed to inject fire extinguishing agent.

This automatic fire extinguishing system 10 is assembled into an electric discharge machine (not shown), and detection signals from a plurality of fire detection sensors attached to a part of the machine are sent to the plunger solenoid 12 via a lead wire 15. supply is becoming available.

FIG. 2 shows a drive circuit for the plunger solenoid 12. In FIG. 2, A is a switch that is turned on by a fire detection signal from the sensor;
The current supplied from the power supply input terminals 16 and 17 is switched on and off. In FIG. 2, TR is a timer connected between power lines a and b, B is a normally closed switch that is turned off by the timer TR, and SL is a solenoid coil of the plunger solenoid 12. , the switch B is connected in series to the solenoid coil SL. moreover,
A resistor R is connected in parallel to the switch B.

Next, the operation of the automatic fire extinguishing system 10 of this example will be described.

First, under normal conditions, the switch A is in the off state and no current is supplied to the solenoid coil SL, so the plunger 12a does not operate.

On the other hand, when a fire is detected by a sensor (not shown) and a fire detection signal is supplied from the sensor to the plunger solenoid 12 via the lead wire 15, the switch A is turned on. In response, a drive current necessary to attract the plunger 12a to the forward position is supplied to the solenoid coil SL, and the plunger 12a is attracted downward with a large torque and moved to the forward position. Along with this, the valve opening/closing main shaft 14 of the extinguisher 11 is pressed by the plunger 12a, the extinguishing agent injection valve is opened, and the extinguishing agent is injected.

When a predetermined short time has elapsed after the start of extinguishant injection, switch B is turned off by the action of timer TR. As a result, the resistance R enters in series with the solenoid coil SL, so the current flowing through the solenoid coil SL becomes smaller than the drive current, and the plunger 12a is held in the forward position by a small torque due to the small current. Ru.

In this case, a reaction force (for example, about 50 kg) acts on the plunger 12a from the main shaft 14, but due to its nature, once the plunger solenoid 12 is activated to the forward position (suction position), it is operated by a small current. It is held in the forward movement position by torque. Therefore, the spraying of extinguishing agent does not stop due to the back movement of the main shaft 14, and the spraying continues thereafter.

According to the automatic fire extinguishing system 10 having such a configuration,
During startup, a large current is applied for a short period of time to generate maximum torque, which presses the valve opening/closing main shaft 14 and injects extinguishing agent, while after a short period of time has elapsed from startup, a small current is applied to generate the minimum torque. By holding the plunger 12a at , the fire extinguishant injection state is continued. Therefore, the extinguishing agent injection operation can be carried out reliably, and since a small current is passed through the solenoid coil SL after startup, there is no possibility that the solenoid coil SL may remain in an overheated state due to a large current. Inconveniences such as shortened lifespan and malfunction of the solenoid coil SL can be avoided.

Furthermore, in this example, the plunger solenoid 12 is integrally attached to the extinguisher 11, and the plunger 12a directly presses the valve opening/closing main shaft 14, so that the conventional mechanical interlocking means is not required. This makes it possible to reduce the size and cost, and also to obtain a highly reliable device without malfunction.

Although one embodiment of the present invention has been described above, the present invention is not limited to the embodiment described above, and various modifications and changes can be made based on the technical idea of the present invention.

For example, by activating a timer,
The power supply may be switched after a predetermined short time has elapsed since the start of the plunger solenoid 12 to reduce the current supplied to the solenoid coil SL. In this case, power consumption can be saved.

f Effects of the invention According to the invention, the drive current necessary to attract the plunger to the forward position is applied to the solenoid coil only for a short period of time from the start of the plunger solenoid for operating the fire extinguisher, thereby generating a large torque. Therefore, even if a small plunger solenoid is used, the function as an automatic fire extinguishing system can be fully fulfilled. Furthermore, after the period has elapsed, a current smaller than the drive current is passed through the solenoid coil to hold the plunger in the forward movement position, which makes it possible to suppress unnecessary current consumption and prevent overheating of the solenoid coil. It is possible to prevent this, and it is possible to extend the life of the plunger solenoid and, by extension, the automatic fire extinguishing system itself. Therefore, according to the present invention, it is possible to provide an automatic fire extinguishing system that is small, inexpensive, and highly reliable.

[Brief explanation of the drawing]

Figures 1 and 2 show one embodiment of the present invention, in which Figure 1 is a front view of an automatic fire extinguisher, Figure 2 is a drive circuit diagram of a solenoid coil, and Figure 3 is a conventional automatic fire extinguisher. It is a schematic front view of a fire extinguishing device. 10... Automatic fire extinguishing device, 11... Fire extinguisher, 12
... Plunger solenoid, 12a... Plunger, 14... Valve opening/closing main shaft, A, B... Switch, SL... Solenoid coil, TR... Timer, R... Resistor.

Claims (1)

[Scope of utility model registration request] In an automatic fire extinguishing system in which the fire extinguishing agent injection valve of a fire extinguisher is operated by a plunger solenoid, for a short period of time from the start of the plunger solenoid, the driving current necessary to attract the plunger to the forward position is supplied to the solenoid coil. A current is passed through the solenoid coil to generate a large torque, and after that period, a current smaller than the drive current is passed through the solenoid coil to hold the plunger in the forward position with a small torque. Features an automatic fire extinguishing system.