JPS5829575B2 - gas analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an analyzer for engine and other exhaust gases;
The purpose is to enable high-speed and highly accurate analysis.

For example, in order to implement energy saving and exhaust gas countermeasures in engines, it is necessary to measure changes in the combustion state from cycle to cycle by sampling and analyzing gas from within the engine cylinder.

Conventionally, in order to determine the local combustion state within an engine, gas within the engine is sampled by opening a gas sampling valve in synchronization with the crank angle, and analyzed using gas chromatography.

Although this gas chromatography method is an effective method that allows stable and highly accurate analysis, it requires a longer analysis time than the sample collection period.

In other words, the sampling analysis conditions include that the amount of sample required for analysis is small, that the amount of sample collected can vary, that correct analytical values can be obtained even if the sample concentration changes during analysis, and that The time required for one analysis is extremely short.

Although it is effective to use a quadruple barrel mass spectrometer that performs analysis in vacuum to satisfy these conditions, it has the disadvantage that the orifice that introduces the sample into the vacuum is easily clogged by particulate matter in the sample. .

The present invention uses this quadruple barrel mass spectrometer to provide a gas analyzer having a structure that satisfies the above conditions and prevents orifice clogging.

The structure of the device of the present invention will be explained below with reference to the drawings.

The structure of the analyzer in FIG. 1 and FIG. 4 is completely the same, but FIG. 1 shows an example of gas separation analysis, and FIG. 4 shows an example of air-fuel ratio measurement.

Therefore, the structure will be explained using FIG. 1 as a representative example.

1 is a main body of the apparatus, and 2 is a sample gas introduction tube to the main body 1 of the apparatus.

Reference numeral 3 denotes an orifice provided in the sample gas introduction section within the main body 1 of the apparatus.

As shown in FIGS. 2 and 3, a gas discharge passage 5 is formed in the upper vicinity of the orifice 3 and is bent upward by an upwardly inclined wall 5a, and is configured to communicate with the suction pump 4 and discharge the gas to the atmosphere. has been done.

Further, a vacuum chamber 8 is formed below the orifice 3 and communicates with a vacuum pump in combination with a diffusion pump 6 and a suction pump 7.

In this vacuum chamber 8, a pair of quadruple barrel mass spectrometers 11a are installed on the left and right sides thereof.

11b is disposed in communication with the vacuum chamber 8 in a crisscross manner.

It is desirable that the positions of the pair of left and right quadruplex mass spectrometers 11a, 11b and the orifice 3 be equidistant.

Furthermore, an orifice 3 and a quadruple seed mass spectrometer 11a are located in the vacuum chamber above the criss-crossing portion.

11b, and a second on-off valve 10 is provided below to open and close between the quadruple seed mass spectrometers 11a, 11b and the diffusion pump 6 of the vacuum pump. There is.

12a and 12b are respective quadruple seed mass spectrometers 11a
, 11b and the processor 13, and is used to correct changes in sample volume (pressure) that occur during analysis.

The apparatus of the present invention having the above structure operates by opening the first on-off valve 9 and the second on-off valve 10, operating the suction pump 4 and the vacuum pump of the combination of the diffusion pump 6 and the suction pump 10, and operating the sample gas introduction tube. Gas is introduced from 2.

A small amount of sample gas required for analysis (0.01 to 0 in terms of atmospheric pressure per analysis) is introduced into the orifice 3.
．． 06uA? ) is sucked into the vacuum chamber 8 through the orifice 3, and most of the introduced gas is drawn by the suction pump 4 and exhausted to the atmosphere through the exhaust passage 5.

At this time, the sample gas passing through the orifice 3 has the fine particles contained in the introduced gas removed, thereby preventing the orifice 3 from being blocked by the fine particles.

This is because the gas introduced from the sample gas introduction tube 2 collides with the upwardly inclined wall 5a near the upper part of the orifice 3, and the upwardly curved exhaust passage 5 is pulled by the suction pump 4, so that the particles enter the main stream of the gas. This is because it has the effect of moving away from the orifice 3 by inertial flow.

Therefore, fine particles do not pass through the orifice 3 and adhere to it, thereby preventing clogging as described above.

The sample gas sucked into the vacuum chamber 8 is subjected to necessary analysis by a pair of quadruple species mass spectrometers 11a and 11b, and data is collected from the data by a processor 13.

FIG. 1 shows an embodiment in which the apparatus of the present invention is applied to the separation and analysis of engine exhaust gas.

That is, the sample gas introduction pipe 2 is connected to a gas sampling valve 14a attached to the exhaust system of the engine 14, and samples are intermittently collected using an inert gas 16 such as helium or argon as a carrier gas. The sample is divided and introduced into the main body 1 of the apparatus.

One of the quadruple seed mass spectrometers 11b performs compositional analysis (separation analysis) of the sample, and at the same time, the other quadruple seed mass spectrometer 11a measures and corrects variations in the sample amount (pressure).

The start of analysis by one of the quadruple seed mass spectrometers 11b is as follows:
There are two methods: one is to perform analysis at a constant time interval, and the other is to start analysis when the sample amount (pressure) exceeds a certain level.

Next, FIG. 4 shows an embodiment in which the apparatus of the present invention is applied to the measurement of the air-fuel ratio of an engine.

This embodiment differs from the embodiment shown in FIG. 1 in that an oxidation catalyst 17 with a temperature controller 18 is installed in the sample gas introduction tube 2, and that oxygen or
A mixed gas 16 of helium, argon, etc.) is added to the sample gas.

This completely oxidizes the unburned components of the sample gas collected into carbon dioxide.

As for the sample gas introduced into the apparatus body 1, a small amount of sample gas from which fine particles have been removed is sucked into the vacuum chamber 8 through the orifice 3, as in the case of the embodiment shown in FIG. The analyzer 11b measures carbon dioxide, and the other quadruple seed mass spectrometer 11a measures nitrogen.

When samples are taken intermittently, good measurements can be obtained by monitoring the nitrogen output signal, determining that a sample has been introduced when this output exceeds a certain value, and starting the measurement.

Since the composition of air (nitrogen, oxygen, argon, etc.) is always at a constant ratio, the amount of nitrogen may be measured instead of measuring the amount of air.

Furthermore, if the elemental composition (carbon, hydrogen, oxygen) contained in the fuel is known, the amount of carbon (or oxidized carbon dioxide) may be measured instead of measuring the amount of fuel.

That is, the air-fuel ratio can be determined by completely combusting a mixed gas of fuel and air and measuring nitrogen and carbon dioxide.

As described above, the apparatus of the present invention has the following special effects.

a. Accurate analysis and measurements can be obtained even if there are variations in the amount of sample collected.

b. Even if fine particles are contained in the sample, they are removed, making analysis and measurement unnecessary and preventing orifice clogging.

The amount of sample required for C1 analysis and measurement is small (0.2 to 3 m1 in terms of atmospheric pressure per analysis and measurement).

d. Extremely short measurement time for one analysis (1m5e
c~100m5ec).

e0 Samples can be collected intermittently for analysis and measurement.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of the apparatus of the present invention, and shows an embodiment for gas separation analysis. FIG. 2 is a cross-sectional view of the sample gas introduction section, FIG. 3 is an enlarged cross-sectional view of the main part thereof, and FIG. 4 is a diagram showing an embodiment of the air-fuel ratio measurement using the apparatus of the present invention. 1... Device body, 2... Sample gas introduction tube, 3... Orifice, 4... Suction pump, 5... Discharge passage. , 5a... Inclined wall, 6... Diffusion pump, 7... Suction pump, 9, 10... Open/close valve, 11a, 11b.
...Quadrupole mass spectrometer.

Claims (1)

[Claims] 1 An orifice is provided in the sample gas introduction part of the device body, a gas exhaust passage is formed near the top of this orifice by an upwardly inclined wall that bends upward and communicates with the suction pump, and a vacuum chamber is provided below the orifice by a vacuum pump. is,
A gas analyzer characterized in that a pair of left and right quadruple bucket mass spectrometers are arranged to intersect with and communicate with the vacuum chamber, and open/close valves are provided at the upper and lower portions of the intersection.