JP2000346766A - Portable gas detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically re-drive a pump without requiring the re-closing of a power supply in the short-time rise of negative pressure. SOLUTION: A gas detector has a gas sensor 12 and a suction pump 16 built therein and is equipped with a battery 31, a pressure sensor 17 for detecting the suction pressure of the suction pump 16 and a microcomputer 16 for stopping the supply of power to the suction pump 16 when it is detected that suction pressure rises from a reference value continuously for a predetermined time and re-driving the suction pump 16 when the lowering of suction pressure is detected after the stop of the supply of power and, when suction pressure rises by a factor other than the suction of a liquid, the removal of the rising cause of suction pressure is detected by the pressure sensor 17 to automatically re-drive the suction pump 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable gas detector having a function of displaying a concentration based on a signal from a gas sensor and a function of issuing an alarm.

[0002]

2. Description of the Related Art In a portable gas detection device, the suction pressure of a suction pump is applied to a sampling nozzle to take the air in the environment into a gas sensor such as a hot-wire semiconductor gas sensor.
The concentration of the target gas is converted into an electric signal and displayed on the display, and when the alarm level is exceeded, an alarm means such as a buzzer is sounded. Since this portable gas detection device is used by bringing the suction port of the sampling nozzle into contact with the position to be measured, there is a problem that water in the puddle of the environment to be measured may be sucked up to the sensor and the sensor is destroyed. . To avoid this problem, an air filter having water repellency is mounted between the sampling nozzle and the sensor. By inserting an air filter, the entry of moisture into the gas sensor can be prevented as much as possible. Since the moisture passes through the air filter, a measure is taken to forcibly stop the suction pump when the load current of the suction pump continuously exceeds a predetermined value for a predetermined time. On the other hand, since such a portable gas detection device usually uses a dry battery as a power supply, at the start of use, the suction port of the sampling nozzle is used to check the degree of battery consumption and to check the operation state of the pump. May be sealed with a finger or the like for a short time to check the suction pressure, or the sampling nozzle may be sealed for a short time by the measured object during measurement. In such a case, the suction pump naturally stops, but if the air filter is not closed with water or the like and the blockage is released in a short time, the operation sequence of the suction pump is restarted. Need to restart the device.

[0003]

However, if a gas sensor that requires a warm-up operation after turning on the power is used as a gas sensor, the warm-up time is required and the work efficiency is extremely reduced. is there. The present invention has been made in view of such circumstances, and the purpose thereof is therefore,
An object of the present invention is to provide a portable gas detection device that can automatically restart a pump without needing to turn on the power again when the negative pressure rises for a short time.

[0004]

According to the present invention, a gas sensor and a suction pump are provided, and a battery and a pressure detecting means for detecting a suction pressure of the suction pump are provided. When the pressure detecting means detects that the suction pressure continuously rises from the reference value for a predetermined time, the supply of power to the suction pump is stopped, and the suction pressure is reduced after the stop. And control means for re-driving the suction pump when is detected by the pressure detecting means.

[0005]

When the suction pressure rises due to a requirement other than the suction of the liquid, if the cause of the increase in the suction pressure is removed, this is detected by the pressure detecting means and the suction pump is automatically driven again.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; FIG. 1 shows an embodiment of the present invention, in which a case 1 is provided with a panel 2 at a position where it can be easily seen when the case 1 is gripped, and a gas inlet 4 serving as a mounting portion for a sampling nozzle 3 on an upper surface. And a channel unit 5 described later. Panel 2
A display 6 for displaying the gas concentration on one side, a power switch 7, a dead zone selection switch 8 also serving as a buzzer sound stop command switch, and a zero point adjustment command switch 9 on the other side.
Etc. are provided.

The display 6 includes a plurality of light emitting elements L1 to L
6 are arranged in a line. When the power switch 7 is turned on, the display shows the progress of the warm-up state of the gas sensor.
It is used to indicate when it exceeds 0, 600, 1000, and 10000 ppm, and to indicate an alarm when the suction pressure further increases.

As shown in FIG. 2, the channel unit 5 has a gas inlet 4 and an exhaust port 11 formed on the surface of a base 10.
On the inner surface of the case 1, a mounting frame 14 having a sensor chamber 13 for accommodating a part of the gas sensor 12 and a mounting portion 18 for a diaphragm pump 16 and a pressure sensor 17 driven by a motor 15 are formed. It is configured.

FIG. 3 mainly shows the flow path of the flow path unit 5 described above. The base 10 has two chambers, a suction chamber 20 and an exhaust chamber 21 separated by a partition wall 19. The suction chamber 20 communicates with the suction port 16a of the suction pump 16, the pressure guiding tube 17a of the pressure sensor 17, and the sensor chamber 13, and the exhaust chamber 21 communicates with the discharge port 16b and the exhaust port 11 of the suction pump 16. I have. The gas inlet 4 is provided with a space 22a having a predetermined volume, and a filter 22 having a gas-permeable and water-repellent membrane 23 mounted on the discharge side. The sampling nozzle 3 is attached to and detached from the suction opening 22b. Mounted as possible.

FIG. 4 is a block diagram showing an embodiment of the present invention. The suction pump 16 and the gas sensor 12 are connected to a battery 31 via a switch 30 and a stabilized power source 32.
Is receiving power from

Gas sensor 12 and pressure sensor 17
Is output to the analog-to-digital conversion means 37. The signal from the gas sensor 12 is
The signal is output to the analog-to-digital converter 37 after the zero point adjustment and the span adjustment are performed by the zero point adjustment and the span adjustment circuit including the operational amplifier 33, the variable resistor 34, the feedback resistor 35, and the like.

The microcomputer 36 processes the gas detection signal and the pressure signal output from the analog / digital conversion means 37 based on the control program of the storage means 38 and the setting data, and is connected via the interface 39. Display panel 6 and buzzer 4 as an alarm means
0 is operated, and further, the start and stop of the suction pump 16 are controlled. Reference numeral 41 in the figure denotes a stable power supply circuit that supplies operating power to the microcomputer 36.

Next, among the operations of the apparatus configured as described above, the operation of the suction pump 17 will be mainly described with reference to the flowchart shown in FIG. When the power switch 7 is operated and the power is turned on (step b), the microcomputer 36 wakes up and the switch 34
Is turned on, the suction pump 16 is operated by the stabilizing power supply 32 (step b) to scavenge the flow path of the gas sensor chamber 13 and the like, and the gas sensor 12 is preheated so that it can be measured. The light emitting elements L1 to L6 are operated by moving and blinking to notify the user that warming up is in progress.

When a predetermined time has elapsed and the movement of the light-emitting elements L1 to L6 has stopped and the measurement has become possible, when the sampling nozzle 3 is brought close to the area to be measured, the atmosphere passes through the filter 22. Then, the gas flows into the gas sensor chamber 13.

When the signal from the gas sensor 12 exceeds the alarm level, the microcomputer 36 sounds a buzzer 40 to alert the user. Hereinafter, when the suction pressure is equal to or lower than the reference value P1 (step c), the suction pump 16 is continuously driven to execute the gas detection operation (step d), and when the power switch 7 is turned off (step e). ), The suction pump 16 is stopped.

On the other hand, if the suction port 3a of the nozzle 3 is erroneously sealed by an object during the measurement, the suction pressure of the suction chamber 20 rises above the reference value P1 (step c). Light-emitting elements L1 to L5 of display panel 6
An alarm is displayed on L6 and an alarm is issued to the user (step t). When the user notices this, the sampling nozzle 3 is moved within a predetermined time T1, for example, within several seconds, and the suction port 3 is moved.
When a is opened, the suction pressure of the suction chamber 20 decreases.
The microcomputer 36 detects a decrease in suction pressure based on a signal from the pressure sensor 17 (step).
Cancel the alarm display (Step 1). Hereinafter, when the suction pressure does not increase to the reference value P1 or more (step
C) Continue the measurement operation (step d).

On the other hand, when a liquid such as water is sucked from the nozzle 3 and the suction pressure rises to the reference value P1 or more (step S1).
C) The microcomputer 36 causes the light emitting elements L1 to L6 of the display panel 6 to display an alarm, and issues an alarm to the user (step S). Even if the user notices this and moves the sampling nozzle 3 to open the suction port 3a, since the membrane 23 constituting the filter 22 is clogged with water, the suction chamber 20 is within the predetermined time T1. Does not return to atmospheric pressure. Thereby, the microcomputer 3
6 indicates that the suction pump 16 is stopped, a warning is displayed on the display panel 6 in a different form, and a buzzer 4 is provided if necessary.
Ring 0 (step nu).

After the predetermined time T2, for example, several seconds, elapses (step), the microcomputer 36 detects the pressure in the suction chamber 20 based on a signal from the pressure sensor 17, and sucks a liquid such as water. In this state, the inflow port is closed by clogging of the filter 22, and the outflow port, that is, the discharge port 16b of the pump is also closed by a check valve 17c provided here.
Since the high suction pressure is maintained (step e), the microcomputer 36 waits for the power switch 7 to be turned off without restarting the suction pump 16 (step w). This can prevent water from entering the gas sensor 12 due to a further increase in negative pressure.

On the other hand, as described above, when the suction port 3a of the nozzle 3 is closed by a finger or the like for a time longer than the time T1 as part of the start-up inspection (Steps C, G, and C).
H), the microcomputer 36 stops the suction pump 16, causes the light-emitting elements L1 to L6 of the display panel 6 to display a warning, and further sounds the buzzer 40 (step).
Nu). In this case, since the nozzle 3 is consciously closed, the user can confirm the capacity of the battery and the normal operation of the pump by an alarm display or an alarm as a reaction.

If the finger is released from the nozzle 3 when the check is completed, the suction chamber 20 drops to a suction pressure P2 suitable for sampling before the predetermined time T2 elapses (step st) (step e). The microcomputer 36 drives the suction pump 16 again to cancel the alarm display (step f), and while the suction pressure is maintained at the reference value P1 or less (step c), the microcomputer 36 continuously drives the suction pump 16 to release the gas. Is detected (step d).

As a result, during the inspection work, the pump 1
Even if 6 has been stopped, it is not necessary to turn on the power again, and therefore, it is possible to perform the measurement without the waiting time associated with the warm-up operation.

In the above-described embodiment, an example in which a hot-wire type semiconductor is used as the gas detecting means has been described. However, an apparatus using another type of gas detecting means such as an electrochemical gas sensor may be used. Even if it is applied, it is apparent that the present invention is effective even when applied to a device using a sensor that requires a long warm-up operation after the power is turned on.

[0023]

As described above, according to the present invention, a gas sensor and a suction pump are incorporated, a battery,
A pressure detecting means for detecting a suction pressure of the suction pump, and stopping supply of electric power to the suction pump when the pressure detecting means detects that the suction pressure has continuously increased from a reference value for a predetermined time. When the suction pressure is detected by the pressure detection unit after the stop, control means for re-driving the suction pump is provided.If the suction pressure increases due to a requirement other than suction of the liquid, If the cause of the increase in the suction pressure is removed, this can be detected by the pressure detecting means and the suction pump can be automatically restarted, so that the measurement can be performed without the waiting time associated with the warm-up operation.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a portable gas detection device of the present invention.

FIG. 2 is a view showing one embodiment of a flow channel unit of the same device.

FIG. 3 is a view showing a channel configuration of the above channel unit.

FIG. 4 is a block diagram showing one embodiment of the portable gas detection device of the present invention.

FIG. 5 is a flowchart showing an operation of the above device.

[Explanation of symbols]

 2 Panel 3 Sampling nozzle 5 Flow path unit 6 Display 7 Power switch 12 Gas sensor 16 Diaphragm pump 16 17 Pressure sensor 22 Filter 31 Battery 36 Microcomputer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shoji Kizaki 2-7-6 Shozuzawa, Itabashi-ku, Tokyo RIKEN Keiki Co., Ltd. (72) Inventor Ryozo Uchikoshi 2-7-6 Shozuzawa, Itabashi-ku, Tokyo RIKEN Keiki (72) Inventor Keizo Iwao 4-1-2, Hirano-cho, Chuo-ku, Osaka City Inside Osaka Gas Co., Ltd. (72) Tetsuya Nakamaru 4-1-2, Hirano-cho, Chuo-ku, Osaka City Osaka Gas Co., Ltd. F term (reference) 2G046 AA01 BA02 BC03 BE02 BG04 CA03 DA01 DC06 DC14 DC17 DC18 DD01 EB01 FB02 2G060 AA01 AB01 AB15 AB24 AB26 AE19 AF02 AF07 AG11 BA05 BB02 BB08 BC03 HA01 HC22 HC25 HD01 HD02 HD03 HE02 KA01

Claims (1)

[Claims] 1. A gas sensor, a suction pump, a battery, pressure detecting means for detecting a suction pressure of the suction pump, and a condition that the suction pressure continuously exceeds a reference value for a predetermined time. When the pressure is detected by the pressure detecting means, the supply of power to the suction pump is stopped, and when a decrease in the suction pressure is detected by the pressure detecting means after the stop, the suction pump is restarted. A portable gas detection device comprising: a control unit for driving.