JPH0352309B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a safety device that detects an abnormal condition such as a fluid leak or fire, and issues an alarm or shuts off the fluid.

Conventional Structure and Problems There is a conventional safety device of this type that uses a commercial power source as the device power source. That is, as shown in FIG. 1, a fluid leak detector 1 is used as an abnormal sensor having a contact output that is turned on during normal operation and turned off during abnormal operation.
Each contact output of the fire detector 2 is connected in series. A DC power source as a device power source is obtained from a commercial power source through a power supply circuit 3. Direct current from the power supply circuit 3 is input to the current detector 4 through the contacts of the fluid leak detector 1 and the fire detector 2. The current detector 4 outputs a normal signal if there is a current flowing through the fluid leak alarm 1 and the fire detector 2, and outputs an abnormal signal if there is no current. The display 5 is driven by this abnormal signal. For example, when the fluid leak detector 1 detects a fluid leak, its contacts are turned off. Then, no current flows through these abnormality sensors, so the current detector 4 detects this and outputs an abnormality signal. The display 5 is driven by this abnormality signal to indicate that there is an abnormality.

This device requires a commercial power source and therefore does not operate normally during a power outage. Therefore, if a power outage occurs due to self-inflicted damage, the equipment may not operate properly and a major accident may occur.

To avoid this, it is possible to use a battery as the device's power source, but simply replacing it with a battery would require a large-capacity battery for relatively long use, which would reduce the overall power of the device. This results in larger sizes and higher prices.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and aims to provide a safety device that can operate for a long time using a relatively small capacity battery.

Structure of the Invention In order to achieve the above object, the safety device of the present invention is provided with a pulse generator that intermittently supplies current to the abnormality sensor, and uses a logic judge to determine the output of the pulse generator and the current flowing through the abnormality sensor. The logic with the output of the current detector whose output level is inverted depending on the presence or absence is determined. If the relationship between the two is unreasonable, the logic judge outputs an abnormality signal, and safety devices such as indicators and fluid cutoff valves are driven by this signal, and the abnormality sensor is only intermittently activated. Since current flows through it, battery consumption is low, and it can be operated for a long time with a small capacity.Since it does not use a commercial power source, it has the advantage of operating normally even during a power outage.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, 6 is a battery as a power source for the device. 7 is a pulse generator that intermittently generates high-level pulses, and 8 is a current detector that detects the presence or absence of current flowing through the abnormality sensors 1 and 2. When there is current, the output is Lo, and when there is no current, it is Hi. .
Reference numeral 9 denotes a logic decider which receives the output of the pulse generator D and the output of the current detector 8, and in this embodiment,
This is an exclusive OR gate.

The operation of the above configuration will be explained below.
First, a case where the abnormality sensors 1 and 2 are normal (that is, both of their output contacts are on) will be described. When a pulse is generated by the pulse generator 7, a current flows through the abnormality sensors 1 and 2, and this is detected by the current detector 8, whose output becomes Lo.
Therefore, the output of the Exclusive OR gate, which is a logic judge, becomes Hi, and the protector 5 is not driven. Further, when the pulse generator 7 does not generate a pulse, that is, when its output level is Lo, no current flows through the abnormality sensors 1 and 2, so the output of the current detector 8 becomes Hi. This allows Exclusive−
The OR gate 9 output becomes Hi, and the protector 9 is similarly not driven.

Next, a case will be described in which one or both of the abnormality sensors 1 and 2 detect an abnormality and their output contacts are off. When there is no pulse output from the pulse generator 7, the output of the Exclusive-OR gate 9 is Hi, as described above, and the protector 4 is not driven. Next, when a pulse is output from the pulse generator 7, the contacts of the abnormality sensors 1 and 2 are off, so no current flows. Therefore, the output of the current detector 8 becomes Hi. Since both inputs of Exclusive-OR9 become Hi, its output becomes Lo. This Lo output is an abnormal signal, and the protector 5 is driven by it.

Next, a case will be described in which a failure occurs in which the output of the current detector 8 is fixed at Hi or Lo. In this case, since one input of the Exclusive-OR 9 is always Hi or Lo, when the output of the pulse generator 7 becomes Hi or Lo, an abnormality signal is output and the protector 5 is driven.

As described above, according to this embodiment, the pulse generator intermittently generates pulses for causing current to flow through the abnormal sensor, the current detector detects whether or not current flows through the abnormal sensor, and the pulse generator A logic judge determines the relationship between the presence or absence of a pulse output and the presence or absence of a current from the current detector, and if the relationship between the two is unreasonable, an abnormal signal is output, and this abnormal signal drives the protector, so the current This has the effect of being able to detect the abnormal state of the abnormality sensor without constantly supplying it to the abnormality sensor, and reducing battery consumption. Also, the current detector is broken and its output goes high.
Even if it is fixed to either Low or Low, the logic judge outputs an abnormal signal, making it fail-safe.

In the above embodiment, as a logical judge
We used only Exclusive−OR, but in addition to this
Add a memory to latch the abnormal signal output of Exclusive-OR, or install a counter to count the number of times an abnormal signal is generated to prevent malfunction, and set a protector when the count value of this counter reaches a predetermined value. It is easy to think of improvements such as outputting a drive signal for driving the motor.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained. That is, the safety device can be configured without using a commercial power source and can function normally even during a power outage. Since current is intermittently passed through the abnormality sensor, battery consumption is low and its operating time can be extended. Furthermore, by determining the logic of the relationship between the pulse output from the pulse generator and the output of the current detector, a fail-safe configuration can be achieved even in the event of failure of the current detector, resulting in high safety.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional safety device, and FIG. 2 is a block diagram of a safety device according to an embodiment of the present invention. 1... Gas leak detector (abnormality sensor), 2...
Fire detector (abnormality sensor), 5...Safety device, 6...
...Battery, 7...Pulse generator, 8...Current detector, 9...Exclusive-OR (logic judge).

Claims (1)

[Claims] 1. A pulse generator that detects an abnormality such as a liquid leak or fire and generates a pulse to intermittently flow current to an abnormality sensor that has a contact output that is turned on when normal and turned off when abnormal, and from the pulse generator. a current detector that detects the current flowing through the abnormality sensor and inverts its output level depending on the presence or absence of the current;
a logic determiner that receives the pulse output from the pulse generator and the output of the current detector as input, determines the logicality of the relationship between the two, and outputs an abnormal signal when the relationship is irrational; A safety device that is equipped with a safety device such as an alarm or a fluid cutoff valve that is driven by the output of an abnormality signal, and a battery as the device's power source.