JPH02115741A - Gas sensor device - Google Patents

Abstract

PURPOSE:To perform measurement with a high precision by calibrating a signal processor at the time of introducing calibrating gas to a sensor from a calibrating gas introducing tube. CONSTITUTION:A sensor part 1 has a suction pump 3, and gas to be examined is introduced from a gas sampling tube 4 to a semiconductor gas sensor 5 by the pump 3 and is discharged out of a system through a sampling gas absorbing unit 10. The signal inputted from the sensor 5 to a signal processor 2 is supplied to an operation part 13 through an amplifying part 11 and an A/D converting part 12. The operation part 13 not only converts the input signal to a concn. signal and outputs it but also integrates the measuring time to output a calibration timing signal at intervals of a set certain time. This calibration timing signal is inputted to a switching control part 14, and operation signal to a solenoid valve 6 of the gas sampling tube 4 and a solenoid valve 9 of a calibrating gas introducing tube 8 are outputted from the control part 14. Thus, the gas concn. is easily measured with a high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a gas sensor device, and more particularly to a gas sensor device that makes it possible to automatically adjust offset and the like.

[Prior Art] There are various types of gas sensors, and most of them require periodic calibration for changes in gas detection characteristics over time. Conventionally, in this calibration, a worker periodically supplies a standard gas to the sensor, and manually performs zero calibration.
I am trying to adjust the points.

[Problem to be solved by the invention] In conventional gas sensor devices, during this calibration, sampling is temporarily stopped and the zero point (offset) is manually adjusted by the worker using standard gas, which is time-consuming. . In particular, when adjusting a large number of sensors at once, the time required for the calibration work is extremely long.

SUMMARY OF THE INVENTION An object of the present invention is to provide a gas sensor device that can automatically perform calibration work and easily perform stable and highly accurate gas concentration measurement using a gas sensor.

[Means for Solving the Problems] The gas sensor device of the present invention includes a gas sampling tube, a sensor provided on the gas sampling tube, and a signal processor that processes the signal of the sensor and outputs a concentration signal. a calibration gas introduction pipe connected to a gas sampling pipe upstream of the sensor; and a flow path selection means for selectively selecting the gas sampling pipe and the calibration gas introduction pipe to flow gas to the sensor. and means for calibrating the signal processor while the calibration gas is being introduced into the sensor from the calibration gas introduction tube.

[Function] In the gas sensor device of the present invention, when the gas introduced from the sampling tube (test gas) comes into contact with the sensor,
For example, the impedance of the sensor changes. This sensor signal is output through a signal processor.

When performing calibration in the apparatus of the present invention, the following method is used, for example.

First, in a gas sensor device that continuously measures the concentration of the target component in the sample gas, a calibration timing signal is output a certain period of time after the end of the previous calibration, and based on that signal, the sample gas is transferred from the sampling tube to the gas sensor. At the same time as the introduction of gas is interrupted, calibration gas is supplied to the gas sensor from the calibration gas introduction pipe.

The signal processor monitors the state of the output signal of the gas sensor, and when the state becomes stable, stores the signal from the sensor as a zero point (offset) signal. Thereafter, the introduction of the gas to be detected is resumed, normal measurements are performed, and the signal from the gas sensor is corrected using the stored offset, which is used to output a concentration signal.

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

FIG. 1 is a configuration diagram of a gas sensor device of the present invention.

The device of this embodiment is composed of a sensor section 1 and a signal processor 2. The sensor section 1 has a suction pump 3, and the suction pump 3 is configured to introduce the sample gas into the semiconductor gas sensor 5 through the gas sampling pipe 4 and release it to the outside of the system through the sampling gas adsorption unit 10. .

The gas sampling pipe 4 is provided with a solenoid valve 6 that performs two operations: opening and closing. An introduction pipe 7 is provided between the solenoid valve 6 and the semiconductor gas sensor 5, and the three ends are connected to the solenoid valve 6 and the semiconductor sensor 5. A calibration gas introduction pipe 8 is connected via a solenoid valve 9. A test gas or a calibration gas is introduced into the semiconductor sensor 5 by selecting whether to open or close the solenoid valve 6 or 9. In this embodiment, a clean gas having a target gas component concentration of 0 is used as the calibration gas. The sampling gas adsorption unit 10 is filled with an adsorbent that is compatible with the gas to be detected, and after the measured gas is adsorbed, it can be released outside the system.

Next, the signal processor 2 will be explained. The signal input from the semiconductor gas sensor 5 to the signal processor 2 is sent to the amplifier section 11.
A/D signal converter 12. After processing in the calculation unit 13, it is output as a density signal. The signal amplified by the amplification section 11 is converted into a digital signal by the A/D signal conversion section 12 and then input to the calculation section 13 . The arithmetic unit 13 containing a microcomputer converts the input signal into a concentration signal and outputs it. In addition to the function of storing an offset value and the function of correcting the detected concentration value using this offset value, the calculation unit 13 has a function of integrating measurement time and outputting a calibration timing signal at every set fixed time. There is. This calibration timing signal is input to the switching control section 14, which outputs an operating signal to the electromagnetic valve 6 of the gas sampling tube 4 and the electromagnetic valve 9 of the calibration gas introduction tube 8. The activation signals of these two solenoid valves are alternative, and when one valve is "open", the other is "closed".

In addition, the calculation unit 13 has a function of observing the state of the signal manually input from the offset unit and detecting the stability of the change. The signal at the time when the output of the sensor 5 becomes stable after flowing the zero calibration gas, which gradually stabilizes the sensor output value, is stored as an offset value. Thereafter, the solenoid valve 6.9 is operated in the opposite direction from when the calibration was started.

The operation pattern of such a gas sensor device is as shown in the flowchart shown in FIG.

First, the entire device starts up and takes measurements. Here, the input signal from the gas sensor is amplified, A/D converted, and then manually input to the calculation unit 13, where the input signal level is continuously measured, corrected with a stored offset, and output as a gas concentration. .

When the continuous measurement time reaches the set time set in the calculation section 13, a calibration timing signal is output from the calculation section 13, and the switching control section 14 closes the solenoid valve 6 and opens the solenoid valve 9. Therefore, suction of the sampling gas is discontinued, and the calibration gas (for example, pure gas) is supplied to the semiconductor gas sensor 5.
supplied to By selecting the route in this way, the signal from the semiconductor gas sensor 5 output at the time of zero calibration, which starts calibration, is amplified and input manually to the calculation section. Then, it is confirmed that the input signal has been stabilized for a certain period of time, and the calculation unit 13 stores the value at this time as the value of the 0 point (offset). At the same time, the output of the calibration timing signal is stopped, and the switching control section 14 starts the calibration gas solenoid valve 9.
, and open the solenoid valve 6 of the sampling tube. By selecting the route in this manner, measurement of the gas to be detected is restarted. By repeating this, the gas sensor device of the present invention continues measurement.

Although the device of this embodiment requires two three-way solenoid valves, a three-way valve may also be used.

[Effects of the Invention] As detailed above, the gas sensor device of the present invention can perform measurement 1
Calibration switching can be performed automatically, and highly accurate gas concentration measurement can be performed with great ease.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the gas sensor device of the present invention, and FIG. 2 is a flowchart showing the operation. 2...Signal processor, 4...Gas sampling tube,
5...Semiconductor gas sensor, 6.9...1! Magnetic valve, 8... Calibration gas introduction pipe, 13... Calculation unit,
14...Switching control section. Figure 2 Agent Patent Attorney Tsuyoshi Shigeno

Claims (1)

[Claims] (1) In a gas sensor device that includes a gas sampling pipe, a sensor provided in the gas sampling pipe, and a signal processor that processes the signal of the sensor and outputs a concentration signal, gas sampling is performed on the upstream side of the sensor. A calibration gas introduction tube connected to the tube, a flow path selection means for selectively selecting the gas sampling tube and the calibration gas introduction tube to flow gas to the sensor, and a calibration gas introduced into the sensor from the calibration gas introduction tube. 1. A gas sensor device comprising means for calibrating a signal processor when the signal processor is being calibrated.