JPS62123347A - Gas sensor - Google Patents

Abstract

PURPOSE:To facilitate the adjustment of sensitivity, by comparing the output value of concentration when a gas to be sensed is detected with set operating value to discriminate the existence of abnormality. CONSTITUTION:When a desired sensitivity is set a with ten key 10, it is memorized into RAMs 1 and 11, then transferred to RAMs 2 and 12 and a pulse with the frequency corresponding to the sensitivity memorized is sent to a micropump 5 through a pump controller 7. Each time receiving a pulse, the pump 5 emits a fixed amount of sample gas supplied from a sample container 6 through a pipe 3 so that the gas concentration in a detecting chamber 4 will correspond to a set sensitivity. The current output value of a gas sensor element 1 each is sent to a CPU 8 by an A/D converter 9 and memorized into RAMs 3 and 13 as said operating value. Now, when the sensing chamber 4 is opened, the gas being sensed advances and the gas concentration detected with the element 1 and sent to the CPU 8 through the converter 9 to be compared with set values memorized in the RAMs 3 and 13. When the output value of concentration of the gas being sensed is larger than a set value, abnormality is alarmed by a display unit 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas detector, and particularly to a gas detector having an automatic sensitivity adjustment function.

A conventional gas detector has a gas detection element 1, as represented by the circuit connection shown in FIG. Compensation cable 2, standard resistance R,,,'! A
Connect the connecting resistor VR to the bridge against the source E, connect the alarm 5 to the bridge operating point, and place it in a sealed box with a predetermined concentration inside, so that the alarm 3 will operate in that state. I was adjusting the variable resistor VR.

The problem that the invention aims to solve: Before shipping, the operating point is adjusted according to the installation location and installed at the site, but after the gas detector is installed, it does not suit the environment of the installation location. Therefore, if it becomes necessary to change the sensitivity, or if the sensitivity becomes distorted due to aging, remove the detector, bring the sealed box to the site, and then go inside and readjust it. This was extremely troublesome as I had to reattach it from the beginning.

Taking these points into consideration, the present invention incorporates a device in the detector that injects sample gas at the time of a set meal, and electrically controls this to bring the vicinity of the detection element to a predetermined gas concentration corresponding to the set sensitivity. The output value of the detection element at that time is stored as the operating setting value of this detector, and the output value of the concentration when the detected gas is detected during monitoring is compared with the operating setting value to determine whether there is an abnormality. As described above, according to the present invention, the sensitivity can be easily adjusted without the hassle of bringing a sealed box to the site, removing the detector, readjusting it, and reinstalling it.

Embodiment To explain the present invention with reference to the embodiment shown in the figures, FIG. 1 is a block diagram showing the configuration of the present invention, and parts corresponding to FIG. ing.

This detection chamber 4 is constructed so that outside air can freely circulate during monitoring, and it is closed only during sensitivity adjustment. In addition, a micro pump 5 is installed in the detection chamber 4 so that an injection port opens on the inside thereof, and a sample container 6 is installed near the micro pump 5 to supply alcohol, etc., which will become a sample gas, to the pump 5 through a vibrator 3. There is. The micro pump 5 may be of a piezo type or a thermal type, but any type that can inject a fixed amount of gas each time a pulse is applied may be used. 7 is a pump controller that sends pulses from the CPU 8 to the micro pump 5 a number of times according to the set sensitivity, and each time the sample gas is quantitatively injected several times from the micro pump 5, so that the inside of the detection chamber 4 reaches the set sensitivity. In order to inject a zero amount of gas at a corresponding predetermined gas concentration, in addition to the micropump described above, an electromagnetic valve may be used to control the opening and closing of a gas cylinder filled with a sample gas under pressure by pulses.

In this case, the amount of gas injected is determined by the time width of the pulse. 9 is an A/D converter which A/D converts the output of the gas detection element 1 and inputs it to the CPU 8. 10 uses the numeric keypad to set the sensitivity and C! This is for issuing various commands to PU 8, and RAM 1, 1
1 is a RAM memory that stores the operation process of the numeric keypad, RA
M2.12 is a RAM memory that stores the set sensitivity selected by the numeric keypad, and RAMs 5 and 13 store the output value of the gas detection element 1 at the concentration of the sample gas to be injected corresponding to the set sensitivity as the operation set value. RAM memory,
The ROM 14 is a ROM memory that stores the cptya program, the display 15 sequentially displays the processing status of OP[78, and the output value of the gas detection element 1 at the concentration of the gas to be detected during monitoring is stored in the RAM 3. This is a device that notifies you of an abnormality when the value is greater than the operating setting value stored in 13. Next, an explanation will be given of the operation of the gas detector of the present invention, centering on the CPU 8. First, press the desired number key on the numeric keypad 10 to set the desired sensitivity, and the process is R
It is stored in AM 1 and 11, and finally transferred to RAM 2 and 12 when the operation is completed. And RAM 2.

A number of pulses corresponding to the sensitivity stored in the micropump 12 are sent to the micropump 5 through the pump controller 7, and each time the micropump 5 receives the pulses, it pumps a fixed amount of sample gas using alcohol etc. supplied from the sample container 6 through the pipe 3. Inject. Therefore, the gas concentration in the detection chamber 4 becomes a value corresponding to the sensitivity set with the numeric keypad 10.

Then, the output value of the gas detection element 1 at this time is A/D
FLAM3. is sent to CPU8 through converter 9.
13, the operating setting values of this gas detector are stored, and the sensitivity adjustment is completed.

Therefore, when the detection chamber 4 is opened to allow air to flow freely during monitoring, the gas to be detected enters the detection chamber 4, the gas concentration is detected by the gas detection element 1, and the output value is determined by the A/D.
After being converted into a digital value through converter 9, C
It is sent to the PU 8 and compared with the operation setting values already stored in the RAMs 3 and 13. At this time, the output value at the concentration of the gas to be detected is RAMP.

13, the gas detector is activated and the display 15 indicates this abnormality. The display 15 displays an appropriate amount of each necessary item in the process of setting the sensitivity using the numeric keypad 10 as described above.

In addition, in the above embodiment, the sensitivity setting was explained as being performed by operating the numeric keypad, but it can also be done by selecting from the default values. In this case, the above default setting value is used instead of RAM 1. It is sufficient to provide a ROM for storing , and a selection switch for selecting a desired setting value from the ROM instead of the numeric keypad. Next, Figure 2 is a 70-chart of the main program, Figure 6 is a flowchart of the numeric keypad reading program included in the flowchart of the main program in Figure 2, and Figure 4 is a 70-chart of the main program in Figure 2. 70 sensitivity setting programs included
- Shows a chart.

Effects of the Invention In the present invention, a device for quantitatively injecting sample gas is built into the detector, and it is electrically controlled to bring the vicinity of the detection element to a predetermined gas concentration corresponding to the set sensitivity. The output value of the element is stored as the operating setting value of this detector, and the output value of the concentration when the detected gas is detected during monitoring is compared with the above operating setting value to determine whether there is an abnormality. This eliminates the hassle of bringing a sealed box to the site or removing the detector, and allows for easy sensitivity adjustment.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the present invention, Figures 2 and 3.
4 are flowcharts of the main program, numeric keypad reading 2 program, and sensitivity setting program, respectively, and FIG. 5 is a configuration wiring diagram of a conventionally known gas detector. In the figure, 1 is a gas detection element, 2 is a compensation element, 3 is an alarm, and 4
is the detection chamber, 5 is the micro pump, 6 is the sample container, 7 is the pump controller, 8 is the CPU, 9 is the A/D converter, 1o is the numeric keypad, 11, 12, and 13 are the RAM, 1
4 is a ROM, and 15 is a display. Patent applicant: Nomi Disaster Prevention Industry Co., Ltd. Figure 2

Claims (7)

[Claims] 1. A detection chamber that seals a monitoring space in which a gas detection element is arranged during sensitivity adjustment, a sample gas injection device that injects a fixed amount of sample gas into the detection chamber, a sensitivity setting means, and a detection chamber that corresponds to the set sensitivity. means for controlling the sample gas injection device so as to achieve a predetermined gas concentration; means for storing an output value at the sample gas concentration detected by the gas detection element as an operation setting value; A gas detector comprising means for comparing the output value at the detected concentration of the gas to be detected with the operation setting value to determine the presence or absence of an abnormality. 2. The quantitative sample gas injection device injects a fixed amount of sample gas each time it receives a pulse, and the means for controlling the sample gas injection device sends a number of pulses corresponding to the set sensitivity to the sample gas injection device to send the sample gas into the detection chamber. Claim 1, wherein the gas concentration is controlled to a predetermined gas concentration corresponding to a set sensitivity.
Gas detector described in section. 3. A micropump is used as a quantitative sample gas injection device,
3. The gas detector according to claim 2, wherein the injection of alcohol or the like supplied from the sample container is controlled by pulses. 4. The quantitative sample gas injection device injects the sample gas while receiving the pulse, and the means for controlling the sample gas injection device sends a pulse with a time width corresponding to the set sensitivity so that the inside of the detection chamber reaches a predetermined level corresponding to the set sensitivity. The gas detector according to claim 1, wherein the gas detector is controlled to have a gas concentration of . 5. Claim 4: A solenoid valve is used in the sample gas injection device for quantitative measurement, and injection of the sample gas is controlled by opening and closing the discharge port of a gas cylinder filled with the sample gas under pressure using pulses. Gas detector listed. 6. It electrically controls a device that quantitatively injects sample gas, stores the operating setting value of the detection element corresponding to the set sensitivity, and compares the output value of the concentration of the detected gas with the operating setting value during monitoring. The CPU is used to determine whether there is an abnormality or not.
The gas detector according to claim 1, characterized in that the gas detector uses: 7. The gas detector according to claim 1, wherein a numeric keypad is used to set the sensitivity and issue various commands to the CPU.