JPH07253406A - Gas detector - Google Patents

Abstract

PURPOSE:To reset to an original gas detection state rapidly after gas is detected by interrupting supply of suction gas to a sensor when gas to be detected becomes a set concentration or more, and supplying the fresh air. CONSTITUTION:At the time of detecting, an apparatus is in a first connection state, i.e., in the gas detectable state that a suction port 1 is connected to a pump P via a three-way valve V. Atmospheric gas sucked at the port 1 from a detecting position is introduced to a sensor 4 via a gas route 3. When a sensor section S detects a concentration of a set value or more, a motor M sets the valve V to a second connection state by an operation of a detector 5. The pump P is connected to a branch passage 7 having an air intake port 8 to guide the fresh air into the sensor 4. At the time of the second connection state, the pump P is so controlled by the detector 5 as to suck more than that in the first connection state, and hence the fresh air is more rapidly introduced into the sensor 4 as compared with the atmospheric gas, thereby washing gas adhered to the sensor 4 away. When regeneration of the sensor 4 is detected by the detector 5, the motor M again sets the valve V to the first connection state, and the apparatus rapidly becomes the gas detectable state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention comprises an intake port and an exhaust port,
A pump is provided in the gas flow passage connecting the intake port and the exhaust port,
The present invention relates to a gas detection device in which a sensor for detecting a detection target gas in the atmospheric gas sucked from the intake port by the pump is arranged in the gas flow passage and an informing unit for informing the detection result from the sensor is provided.

[0002]

2. Description of the Related Art In a conventional gas detector, the pump is always rotated only in one direction, and the atmospheric gas sucked from the intake port by the pump is always guided to the sensor.

[0003]

In the above conventional structure, the atmospheric gas sucked from the suction port by the pump is continuously guided to the sensor, so that the gas to be detected is detected and an alarm is issued. After that, the atmospheric gas is continuously sucked in, and the gas to be detected continues to flow in the sensor,
When the alarm remained to be emitted, and subsequently, when it was desired to detect gas at another place, the gas leak detection device could not be quickly returned to the reset state. Also, with gas detection,
Since the sensor is exposed to the high-concentration gas to be detected for a long time, the sensor deteriorates quickly and it is necessary to replace the sensor frequently. In view of the above situation, an object of the present invention is to promptly return to the original gas detectable state after gas detection, quickly move to the next detection operation, and prevent deterioration of the sensor. It is to provide a gas detection device.

[0004]

The gas detector according to the present invention is characterized in that the supply of the intake gas from the intake port to the sensor is cut off based on the detection by the sensor of the concentration of the detection target gas or more. An automatic switching device for supplying fresh air to the sensor is provided, and when the output from the sensor to the notifying means becomes lower than a set level, the state is restored and switched to the state in which the atmospheric gas is supplied to the sensor again. The mechanism is provided in the automatic switching device, and the actions and effects thereof are as follows.

[0005]

In other words, when the ambient gas is sucked and taken in by the built-in pump from the intake port and guided to the sensor through the flow passage, and the sensor detects the gas to be detected having a concentration higher than the set value, the notification means detects the result. Is notified. And after notifying the detection result, by the automatic switching device,
The supply of atmospheric gas to the sensor is quickly cut off, fresh air is taken in and guided to the sensor, the concentration of the gas to be detected in the sensor is set to zero level, and the original gas detectable state is restored. Further, after the output from the sensor to the notification means becomes lower than the set level and the above-mentioned restoration is performed, the restoration mechanism automatically restores and switches to a state in which the atmospheric gas is supplied to the sensor again from another location. Can detect gas.

[0006]

Therefore, according to the present invention, after the gas to be detected is detected, it is possible to quickly return to the original gas detectable state in preparation for the next gas detection. Since it is not exposed to the detection gas, deterioration of the sensor can be prevented and the life of the sensor can be extended. As a result, for example, even if the work of detecting the leak location of the gas to be detected is performed at a plurality of locations, it can be detected quickly and accurately, and appropriate measures can be taken easily.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the gas detector of the present invention is constructed as follows. That is, the intake port 1 and the exhaust port 2 are provided, the pump P is provided in the gas flow passage 3 connecting the intake port 1 and the exhaust port 2, and the intake port 1 of the pump P is provided.
A sensor 4 for detecting a detection target gas in the atmospheric gas sucked from the intake port 1 is provided in the gas flow path 3 on the side, and in the gas flow passage 3, an upstream side of the sensor 4, that is, a sensor 4 is provided. Air intake port 8 on the side close to intake port 1
The branch passage 7 provided with can be switched between a first connection state in which the intake port 1 and the pump P are connected via a three-way valve V and a second connection state in which the branch passage 7 and the pump P are connected. Connected for communication.

Further, the sensor 4 is composed of a semiconductor type combustible gas detection sensor, and a detection circuit 5 is connected to the sensor 4 to form a sensor section S. A motor M for selectively switching the three-way valve V to the first connection state or the second connection state is connected to the three-way valve V to form a switching mechanism. Then, the switching mechanism is automatically switched by the detection circuit 5 between the first connection state and the second connection state based on the detection result from the sensor 4 to configure an automatic switching device.

Then, the automatic switching device is set so as to be in the first connection state when the concentration of the detection target gas detected by the sensor section S is zero level, and the concentration of the detection target gas detected by the sensor section S is It is preset to switch the switching mechanism to the second connection state when is equal to or more than the set value.

The detection circuit 5 is provided with an alarm device 9 for issuing an alarm and a display device 6 for displaying the value of the detection result when the detection target gas having a concentration higher than a set value is detected by the sensor section S. The notification means A provided is connected.

Further, the detection circuit 5 is provided with a control device for controlling the suction amount of the pump P so that the suction amount becomes larger in the second connection state than in the first connection state.

That is, during the detection work, the gas detection device is reset to the detection work ready state in advance, and at this time, it is in the first connection state. Then, the intake port 1 is installed at the detection point.
When the gas detection device is operated by bringing the pump close to the pump P,
Atmosphere gas is sucked from the intake port 1, the gas sucked from the intake port 1 is introduced into the sensor 4 through the gas flow passage 3, and the detection result of the sensor unit S detects a concentration equal to or higher than a set value. Then, the detection circuit 5 causes the motor M to automatically switch the three-way valve V to the second connection state. When the three-way valve V is switched to the second connection state by the motor M, the pump P is connected to the branch passage 7 having the air intake port 8, so that fresh air is sucked from the air intake port 8. It is guided into the sensor 4. The pump P is controlled by the detection circuit 5 so that the suction amount of air becomes larger in the second connection state than in the first connection state. Rapidly fresh air is introduced into the sensor 4. When fresh air is introduced into the sensor 4, the sensor 4 that has adsorbed the gas to be detected is quickly washed away by the fresh air.

When the sensor 4 reproduces, the detection circuit 5
Detects this, and based on the result, the switching mechanism switches the three-way valve V to the first connection state again by the motor M,
The gas detector is quickly reset to the gas detectable state.

Another Embodiment Next, another embodiment will be described with reference to FIG.

In the gas detecting device, an intake port 1 and an exhaust port 2 are provided, a gas flow passage 3 connecting the intake port 1 and the exhaust port 2 is provided with a pump P, and the intake port 1 side of the pump P is provided. The gas flow path 3 is provided with a sensor 4 for detecting a gas to be detected in the atmospheric gas sucked from the intake port 1, and a detection circuit 5 is connected to the sensor 4 to form a sensor section S.

The pump P has a positive direction in which the atmospheric gas sucked from the intake port 1 is discharged from the exhaust port 2 through the gas flow passage 3 and a gas sucked from the exhaust port 2 in the gas flow passage 3 The rotation direction of the pump P can be switched to the reverse direction in which the pump P is discharged from the intake port 1, and the rotation direction of the pump P is set to either the forward direction or the reverse direction based on the detection result from the sensor 4. The control signal for switching control is configured to be output from the detection circuit 5.

Further, the detection circuit 5 has a display device 6 for displaying a value of a detection result from the sensor 4, and an alarm device 9 for issuing an alarm when the sensor 4 detects a gas to be detected having a concentration higher than a set value. The notifying means A provided with and is connected.

Further, the pump P is configured such that the rotation direction is in the positive direction when the concentration of the gas to be detected detected by the sensor 4 is zero level, and the concentration of the gas to be detected is equal to or higher than the set value. At times, the rotation direction is reversed so that it is switched and controlled by a signal from the detection circuit 5, and when the pump P is rotating in the reverse direction, it is more sucked than when it is rotating in the normal direction. The rotation speed is controlled so as to increase the amount.

That is, when the gas detecting device is reset to the gas detection workable state, the rotation direction of the pump P is the positive direction. Therefore, when the gas detecting device is operated, the intake air is changed. The gas sucked from the mouth 1
It is guided into the sensor 4 through the gas flow passage 3.

When the sensor section S detects a gas to be detected whose concentration exceeds a preset set concentration, an alarm device 9 gives an alarm and a display device 6
The concentration of the gas to be detected is displayed by, and at the same time, the rotation direction of the pump P is automatically switched to the opposite direction based on the detection result of the sensor 4, and fresh air is sucked from the exhaust port 2 and It is guided into the sensor 4. And
When the pump P rotates in the reverse direction, the suction amount of the gas is controlled to be larger than the amount of gas sucked from the intake port 1 when the pump P rotates in the forward direction. Fresh air is introduced into the sensor 4 more rapidly than when the pump P rotates in the forward direction to suck the atmospheric gas during the detection work, and the sensor 4 is washed away by the fresh air and quickly regenerated. .

Subsequently, when the gas adsorbed by the sensor 4 is completely discharged, the detection circuit 5 detects a zero level, and based on the result, the rotation direction of the pump P is switched to the positive direction again. Then, the gas detection device is quickly reset to the gas detectable state.

It should be noted that although reference numerals are added to the claims of the patent claims for convenience of comparison with the drawings, the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 Circuit diagram of gas sensor

FIG. 2 is a circuit section showing another embodiment.

[Explanation of symbols]

 1 Inlet 2 Exhaust 3 Gas flow path 4 Sensor

Claims (7)

[Claims] 1. A gas flow passage (3) having an intake port (1) and an exhaust port (2) and connecting the intake port (1) and the exhaust port (2).
Is provided with a pump (P), and a sensor (4) for detecting a detection target gas in the atmospheric gas sucked from the intake port (1) by the pump (P) is arranged in the gas flow passage (3), A gas detection device provided with an informing unit (A) for informing a detection result from the sensor (4), wherein the intake port ( An automatic switching device for cutting off the supply of intake gas from 1) to the sensor (4) and supplying fresh air to the sensor (4) is provided, and the output from the sensor (4) to the notification means is set. A gas detection device, wherein the automatic switching device is provided with a restoration mechanism for restoring and switching to a state in which the atmospheric gas is supplied to the sensor from the intake port (1) again when the level becomes lower than the level. 2. A control device is provided to control the intake air amount of the pump (P) so that the intake air amount of the pump (P) becomes large at the time of switching the supply of fresh air to the sensor (4) by the automatic switching device. The gas detection device according to claim 1. 3. A branch passage (7) having an air intake (8) is connected to the upstream side of the sensor (4) in the gas flow passage (3) through a three-way valve (V). , A switchable connection between a first connection state in which the intake port (1) and the pump (P) are connected and a second connection state in which the branch passage (7) and the pump (P) are connected for communication, The automatic switching mechanism is configured by providing a drive unit (M) that automatically switches the three-way valve (V) to a first connection state or a second connection state based on a detection result from the sensor (4). 1. The gas detection device according to 1. 4. The pump (P) comprises the intake port (1).
The normal direction in which the gas sucked from the air is discharged from the exhaust port (2) through the gas flow passage (3), and the exhaust port (2)
It is formed so that the rotation direction can be switched to the opposite direction in which the gas sucked from the air is discharged from the intake port (1) through the gas flow passage (3), and the pump (based on the detection result from the sensor (4) ( The gas detection device according to claim 1, wherein a switching mechanism for automatically switching the rotation direction of P) to one of a forward direction and a reverse direction is provided in the switching device of the pump (P). 5. The gas detection device according to claim 1, wherein the informing unit includes an alarm device. 6. The gas detection device according to claim 1, wherein the notification means is a display device that displays a gas detection concentration. 7. The gas detection device according to claim 1, wherein the sensor (4) is a semiconductor type combustible gas detector.