JP2008286641A - Sampling device and sampling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform analysis with responsiveness, even when pressure fluctuates greatly, in a short time, in a sampling device for sampling sample gas via a sample probe from a gas chamber wherein pressure fluctuation is repeated with a prescribed period and the gas is analyzed. <P>SOLUTION: This device is equipped with an adjusting channel 6, whose one end is connected to the output of the sample probe 5, whose other end is opened to the air, having a channel section larger than the sample probe 5. The device is also equipped with a suction path for sucking the sample gas, in a direction orthogonal to the adjusting channel from the adjusting channel 6 and guiding the gas to a gas analysis means by the action of a suction means. A suction position of the suction path is set on a farther downstream side Ps than a re-adhering point Pc of a jet jetting out from the sample probe into the adjusting channel, in a state where the flow rate of a sample gas flow generated following pressure fluctuation becomes a maximum flow rate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sampling apparatus for analyzing a sample gas by introducing a sample gas sampled from a gas chamber that repeats pressure fluctuations at a predetermined cycle via a sample probe to a gas analysis means by a suction means, and in particular, a pressure The present invention relates to a sampling apparatus and a sampling method capable of performing gas analysis in response to the fluctuation at high speed even when the fluctuation is large.

As this type of sampling device capable of high-speed response, Patent Document 1 discloses a sampling device having a double tube configuration. In the technique disclosed in this document, a double pipe is disposed opposite to the flow of the sample gas (in the direction opposite to the flow direction), and the sample gas is introduced into the inner pipe to perform gas analysis. In the technique disclosed in this document, in the state of analyzing the sample gas, the sample gas is received and received in the inner tube with the tip position of the inner tube protruding slightly upstream from the tip position of the outer tube. The gas is introduced into a gas analyzer for analysis (the state shown in FIG. 2B of Patent Document 1).
On the other hand, when calibrating an analysis system using a calibration gas, the tip position of the inner tube is slightly retracted from the tip position of the outer tube (the inner tube is retracted and there is a dead space near the tip of the outer tube. In the formed state), a calibration gas is introduced into an intermediate passage formed between the inner tube and the outer tube, and the calibration gas is ejected into the dead space, and the gas pressure of the sample gas causes the gas to enter the inner tube. Calibration gas is received and calibration is performed by introducing the received calibration gas to the gas analyzer (the state shown in FIG. 2A of Patent Document 1).
By doing so, it is possible to provide a sampling apparatus that can accurately calibrate the analysis system and also has a certain degree of high-speed response.
A gas analyzer employed in this type of analysis system is basically capable of receiving a sample gas having a predetermined range of flow rate into a gas analyzer under a predetermined range of pressure and performing an analysis for a desired purpose.

Japanese Patent No. 3429421

As an application target of this type of sampling device, there is a case where a gas composition in a combustion chamber of an engine is an analysis target. Here, if the gas in the combustion chamber can be analyzed with good responsiveness, it becomes possible to capture the change in the gas composition in the combustion chamber in real time. For example, in the gas engine, analysis of the presence or absence of blowout of fuel into the exhaust pipe, It is possible to measure the concentration change of the.
Furthermore, if the methane concentration can be analyzed with good responsivity for the gas in the combustion chamber of an engine that uses city gas containing methane as the main component, the change in the concentration of the air-fuel mixture before combustion can be ascertained. It is possible to obtain information that is important in identifying combustion and realizing combustion such as stratified combustion.

However, for example, in a supercharged gas engine that is in practical use today, there are applications in which the pressure in the combustion chamber exceeds 12 MPa. In this example, the pressure change in the combustion chamber occurs in a very short time, so if the gas in the combustion chamber is introduced directly into the analyzer using a conventionally known technique, the gas analysis can be performed with good responsiveness. It was difficult to do. Normally, in this type of gas analyzer, an increase in gas pressure directly leads to an increase in output, but in the case of an engine with a rotational speed of several hundred to several thousand rpm, it is difficult to perform gas analysis in a single cycle. Met.
That is, in such an example, if the conventional technology is applied as it is, the change in pressure greatly affects the analysis, and it is impossible to obtain a reliable analysis result. The sample gas outside the analysis target is sucked into the gas analyzer and the output of the gas analyzer remains at a specific index value, causing problems such as being held for a majority of the time in one cycle, There was a problem that the gas analysis of the combustion chamber could not be performed accurately.

  The object of the present invention is as a sampling device that performs analysis by sampling a sample gas from a gas chamber that repeats pressure fluctuations at a predetermined cycle via a sample probe, even when the pressure fluctuates greatly in a short time. An object of the present invention is to obtain a sampling apparatus capable of performing analysis with good sexuality.

According to the present invention for achieving the above object, a sample gas sampled from a gas chamber that repeats pressure fluctuations at a predetermined cycle via a sample probe is guided to a gas analysis means by a suction means, and the sample gas is analyzed. The characteristic configuration of the sampling device
One end is connected to the outlet of the sample probe, the other end is opened to the atmosphere, and an adjustment channel having a larger channel cross-sectional area than the sample probe is provided,
By the action of the suction means, a suction path for sucking a sample gas from the adjustment flow path in a direction perpendicular to the adjustment flow path and leading to the gas analysis means,
The suction position of the suction path is set downstream of the reattachment point of the jet flow ejected from the sample probe to the adjustment flow channel in a state where the flow velocity of the sample gas flow generated with the pressure fluctuation becomes the maximum flow velocity. There is in being.

  The sampling device according to the present application includes a sample probe and an adjustment channel provided on the outlet side thereof, and the sample gas sampled from the gas chamber is configured to flow through the adjustment channel. And the exit side (downstream side) of this adjustment flow path is open | released by air | atmosphere, and the fixed pressure state is ensured.

  Now, since the sample probe is designed to extract the gas in the gas chamber as the sample gas without greatly affecting the events occurring in the gas chamber, the flow passage cross-sectional area of the probe is considerably reduced. It is supposed to be. Therefore, this flow path functions as a kind of throttle, and the sample gas is sent to the adjustment flow path with a pressure change in the gas chamber, but the pressure fluctuation (flow rate fluctuation) is mitigated in the state in the adjustment flow path, This is accompanied by a time delay for passing through the sample probe. Since the downstream end of the adjustment channel is open to the atmosphere, the gas pressure in the adjustment channel gradually approaches atmospheric pressure as it reaches the channel end.

  In the present application, the flow path cross-sectional area of the adjustment flow path is selected to be larger than the cross-sectional area of the sample probe, so that the sample gas flow that has flowed through the sample probe at a relatively high speed is adjusted as a jet flow. And flows into the adjustment flow path and separates from the flow path wall at the inlet portion of the adjustment flow path. Moreover, in this part, since the state where the flow velocity of the sample gas flow is maintained at a relatively high speed also occurs, a part where the gas pressure is relatively low also occurs in the vicinity of the gas flow outlet. And as it goes downstream, the flow recurs and pressure recovery occurs.

A suction path is connected to the adjustment flow path by sucking the sample gas in the flow path in a direction orthogonal to the flow path and guiding it to the gas analysis means by the action of the suction means.
By sucking the sample gas from the adjustment flow path in this way, the influence of the pressure fluctuation of the sample gas on the gas chamber side is reduced, and the gas in the adjustment flow path is stabilized in terms of pressure and flow rate. It can lead to an analysis means, and it becomes possible to perform the analysis by a gas analysis means satisfactorily. Furthermore, the influence of the dynamic pressure of the sample gas flowing in the adjustment channel can be eliminated by sucking the sample gas in the channel in the direction orthogonal to the channel.

  Furthermore, the suction position, which is the position where the suction path is connected to the adjustment flow path, is a state in which the flow rate of the sample gas flow generated in accordance with the pressure fluctuation generated in the gas chamber is the maximum flow rate. The suction position of the suction path is set on the downstream side from the reattachment point of the jet flow ejected from the nozzle to the adjustment channel.

  Here, the state in which the flow rate of the sample gas flow becomes the maximum flow rate is a state in which the flow rate of the sample gas ejected from the sample probe to the adjustment channel is maximum, and in this state, the largest separation occurs at the inlet portion of the adjustment channel. A region (return basin) is formed. Then, on the downstream side of this region, the flow flows toward the downstream end of the adjustment flow path opened to the atmosphere, and sequentially flows out of the adjustment flow path.

  Now, pressure recovery occurs in the flow at the downstream side of the separation region, and the sample gas can be reliably sucked by the suction means. Therefore, the sample gas that can represent the change in the gas chamber can be sequentially sucked from the suction position, and gas analysis can be performed satisfactorily. On the other hand, when the suction position is set upstream from the reattachment point, the gas that has passed through the reattachment point is sucked in the sample gas that may remain in the return region, and the gas analysis is performed. It can be done and a good analysis cannot be done.

In the above sampling device,
It is preferable that the suction position is a position where the pressure recovers to the atmospheric pressure due to the redevelopment of the sample gas flow downstream from the reattachment point, or a position downstream from the position.

Here, “the position where atmospheric pressure recovers” includes “the position where atmospheric pressure first exceeds atmospheric pressure”, and “the position where atmospheric pressure recovers to atmospheric pressure first. "Position that is 95% or more of".
Even when the suction position is set at a position downstream from the reattachment point, a configuration that requires excessive suction capability to suck the sample gas into the gas analysis means using the suction means is not necessarily preferable. It is not a thing.
Therefore, the suction position is a position where the separation of the flow is eliminated with respect to the jet flow ejected from the sample probe into the adjustment channel, and the pressure is restored to near atmospheric pressure by the re-development of the flow, and the downstream position. In this way, gas analysis can be performed satisfactorily with the flow rate of the gas flowing through the gas analysis means within the range of flow rate that can be analyzed, while using the one having a relatively low suction capacity.

  Now, in the above sampling apparatus, it is preferable that the gas chamber is defined by a cylinder and a piston in the engine, and is a combustion chamber in which fuel burns.

  When this configuration is adopted, the gas present in the combustion chamber provided in the engine can be analyzed well.

Now, in order to sample and execute the analysis of the gas in the combustion chamber of the engine using the sampling device of the present application, the flow path volume to the position where the adjustment flow path is opened to the atmosphere downstream from the suction position, It is preferable that the volume is set to be less than the volume sucked by the gas analysis means per cycle of the engine.
In this configuration, the sample gas flowing from the engine to the adjustment flow path is set so that the flow path volume from the suction position to the position opened to the atmosphere is less than the volume sucked by the gas analysis means per cycle of the engine. When the flow rate of the gas becomes insufficient, the gas flowing into the suction path is the worst (when there is no gas sucked into the suction path from the sample probe side) until the position where the atmosphere is released from the suction position. It becomes a mixed gas of the remaining gas and the atmosphere. Usually, some gas flowing from the sample probe side is included. Therefore, the gas to be analyzed on the gas analysis means side can be a gas that has passed through the suction position to the downstream side of the adjustment flow path and is diluted with the atmosphere. Therefore, the gas analysis means guides only the gas that has passed through the suction position and remains in the atmosphere open from the suction position, which is not preferably the object of analysis again. Can solve the problem.

In the case of adopting this configuration, the flow volume of the adjustment flow path from the suction position to the position opened to the atmosphere downstream from the suction position is less than the volume sucked by the gas analysis means during the intake stroke time of the engine. Preferably it is set.
That is, this configuration directly solves the problem of the intake stroke time. Also in this case, the flow volume of the sample gas flowing from the engine to the adjustment flow path is reduced by setting the flow path volume from the suction position to the position where the air is released to less than the volume sucked by the gas analysis means during the intake stroke time of the engine. In the short stroke, the gas flowing into the suction path remains from the suction position to the position where the air is released to the atmosphere, even in the worst case (when there is no gas sucked into the suction path from the sample probe side). It becomes a mixed gas of gas and the atmosphere. Usually, some gas flowing from the sample probe side is included. Therefore, the gas to be analyzed on the gas analysis means side can be a gas that has passed through the suction position to the downstream side of the adjustment flow path and is diluted with the atmosphere. Therefore, only the gas remaining in the position that is released from the suction position through the suction position and is not preferably intended to be analyzed again is guided to the gas analysis means for analysis. Can solve the problem.

  By analyzing the sample gas using the sampling apparatus described so far, it is possible to satisfactorily analyze the sample gas discharged from the gas chamber that repeats pressure fluctuations at a predetermined cycle.

Embodiments of the present invention will be described with reference to the drawings.
In the embodiment shown below, a sample gas sg is sampled from a combustion chamber 2 (an example of a gas chamber) defined by a cylinder 1a and a piston 1b provided in the engine 1 and in which fuel burns. A case where the analysis is performed will be described.
In this example, the fuel is city gas whose main component is methane, and the mixture g1 of fuel and air is introduced into the combustion chamber 2 while being supercharged by the supercharger 3, and the mixture g1 is supplied in the compression stroke. This is an example in which the gas in the combustion chamber 2 in the spark ignition engine 1 that is compressed and operated by spark ignition is the target of gas analysis.
As the gas analyzer 4 (an example of a gas analyzing means), an analyzer suitable for measurement of so-called THC (total hydrocarbons) is used. This gas analyzer 4 is capable of analyzing THC by the FID method (hydrogen flame ionization method). A sample gas sg is introduced into the gas analyzer 4 at a gas pressure of 101 Pa and a gas flow rate of 3.5 liters / min. By doing so, the gas analysis can be performed satisfactorily.

FIG. 1 schematically shows a sampling apparatus 100 according to the present application that samples and analyzes a sample gas sg from a combustion chamber 2 in a cylinder 1a in accordance with the above-described conditions.
As shown in FIG. 1, the sampling apparatus 100 includes a sample probe 5 connected to the combustion chamber 2, and an adjustment channel 6 having one end connected to the outlet of the sample probe 5 and the other end opened to the atmosphere. I have.
Further, at a predetermined position of the adjustment channel 6, the sample gas sg is sucked from the adjustment channel 6 in a direction orthogonal to the adjustment channel 6 by the action of the sample pump 7 (an example of a suction unit). A suction path 8 leading to a total of 4 is connected.

Hereinafter, each part will be described in more detail.
FIG. 5C schematically shows the configuration of the flow path composed of the sample probe 5 and the adjustment flow path 6.
The sample probe 5 has one end connected to the combustion chamber 2 and the other end connected to the adjustment flow path 6, and samples the sample gas sg in the combustion chamber. The d1) of c) is 0.5 mm, and the channel length (L1 in FIG. 5C) is 1000 mm.

  The adjustment channel 6 has one end connected to the other end of the sample probe 5 and the other end open to the atmosphere. Specifically, the adjustment flow path 6 has a flow path diameter (d2 in FIG. 5C) of 3 mm and a flow path length (L2 in FIG. 5C) of 30 mm.

  As shown in FIG. 5 (c), a step portion 6a is formed between the sample probe 5 and the adjustment channel 6 to rapidly expand the channel cross-sectional area (see FIG. 1). That is, the flow path rapidly expands 6 times from a flow path diameter of 0.5 mm to 3 mm.

The suction path 8 is connected at a right angle to the road wall of the adjustment flow path 6 at a position 20 mm from the tip of the adjustment flow path 6 (the connection side of the sample probe 5). Further, the gas analyzer 4 is connected to the lower side of the suction passage 8 and the sample pump 7 is connected to the downstream side thereof.
In the suction path 8, the sample pump 7 sucks the sample gas sg in the adjustment flow path 6 from the suction position Ps with a constant suction pressure, so that the sample analyzer sg is supplied to the gas analyzer 4 at a gas flow rate within a predetermined range. Introduced and stable gas analysis. In FIG. 5C, the distance from the inlet of the adjustment flow path 8 to the suction position Ps is displayed as Ls.

  Here, as will be described later with reference to FIGS. 5 (a) and 5 (b), the suction position Ps is the amount of the sample gas flow downstream of the reattachment point Pc of the jet Fa ejected into the adjustment flow path 6. At a position where the pressure is restored to almost atmospheric pressure by the redevelopment, the gas analyzer 4 can be sucked into the gas analyzer 4 by the action of the sample pump 7 so as to be able to suck the flow rate within the flow rate range that can be analyzed.

On the other hand, assuming that the volume that the gas analyzer 4 sucks in the time per cycle of the engine 1 is v1, and the flow path volume from the suction position Ps to the atmosphere open end 6b in the adjustment flow path 6 is v2. , V2 is set smaller than v1.
On the other hand, although not corresponding to the example shown in FIG. 5, the configuration upstream of the suction position Ps is the same, and the flow path volume v2 is set to the minimum value to avoid the influence of flow separation due to the edge of the suction position Ps. The distance (5 mm) can be about 5 times the suction aperture (1 mm) at the suction position Ps. That is, the flow path volume v2 can be defined as a favorable minimum value in relation to the suction aperture at the suction position Ps, and the maximum value can be defined in relation to v1 described so far.

Gas State in the Combustion Chamber and Operation of the Sampling Device Hereinafter, the operation of the sampling device 100 shown in FIG. 1 will be described based on the drawings.
FIG. 2 shows the change in gas pressure in the combustion chamber 2, and FIG. 3 shows the inlet (solid line) of the sample probe 5 corresponding to the change in gas pressure in the combustion chamber 2, and the adjustment flow path 6. The flow rates at the inlet (dashed line) and the inlet (dashed line) of the gas analyzer 4 are shown corresponding to the crank angle, respectively.
As can be seen from FIG. 2, in this example, the gas pressure in the combustion chamber 2 changes to about 12 MPa in the positive pressure region.
As shown in FIG. 3, the sample gas sg flows from the combustion chamber 2 to the sample probe 5, the adjustment channel 6, and the suction channel 8 with the change in the gas pressure in the combustion chamber 2. At the inlet of the sample probe 5, a relatively large flow rate change occurs in a relatively limited crank angle region (specific stroke region) during one cycle of the engine 1. On the other hand, at the inlet of the adjustment channel 6, a relatively small flow rate change occurs in a wide crank angle region with a time delay with respect to the change at the inlet of the sample probe. Furthermore, a substantially constant flow rate of sample gas sg flows through the adjustment channel 8.

  From these flow rates, in the adjustment flow path 6 according to the present application, the sample gas sg flows into the adjustment flow path 6 from the combustion chamber 2 via the sample probe 5 with a time delay, but flows into the adjustment flow path 6. In the region where the amount of sample gas flowing into the gas analyzer 4 is larger than the amount of inflow coming (in the case of FIG. 3, the region indicated by A where the crank angle is substantially less than −60 °), it does not necessarily flow into the adjustment channel 6. The incoming sample gas sg is not sucked into the suction path 8.

  FIG. 4A shows the analysis result of THC obtained by the gas analyzer 4 in such a configuration through the combustion chamber 2, the sample probe 5, the adjustment channel 6, and the suction channel 8. This figure also shows the crank angle on the horizontal axis. Further, in this drawing, the expansion / intake / exhaust and compression / ignition are indicated by arrows corresponding to the crank angle.

  As shown in the figure, with compression, the THC concentration increases to a predetermined concentration, ignition occurs while the concentration is maintained, and the THC concentration gradually decreases with expansion. Furthermore, the THC concentration has decreased to almost the minimum value with the progress of expansion / intake and exhaust. Such a qualitative behavior is a sufficiently satisfactory change as a change in the THC concentration in the combustion chamber 2, and the gas analysis in the combustion chamber 2 that has been almost impossible until now by the sampling device 100 according to the present application. It turns out that it is performing well.

Technical Problem and Solution in the Present Application 1 Setting of Suction Position As described above, in the present application, a configuration including the adjustment flow path 6 on the downstream side of the sample probe 5 is adopted. Here, the flow path cross-sectional area in the sample probe 5 and the flow path cross-sectional area of the adjustment flow path 6 are constant in the flow direction, and the flow path is rapidly expanded with a step at the entrance of the adjustment flow path 6. As a result, the flow that flows from the sample probe 5 into the adjustment flow path 6 is separated from the road wall w when it enters the adjustment flow path 6 and reaches the reattachment point Pc. In the cross section, it has a flow component toward the downstream side, which is the atmosphere open side.

FIGS. 5A and 5B schematically show the flow state in the vicinity of the inlet of the adjustment flow path 6 and the pressure at each position along the flow. As shown in these figures, the flow from the inlet of the adjustment flow path 6 to the reattachment point Pc takes the form of the jet Fa separated from the road wall w, and the road wall between the jet Fa and the adjustment flow path 6. A reverse flow (return flow) Fb is formed between w.
On the other hand, as can be seen from FIG. 5B, regarding the flow of the adjustment flow path 6, the vicinity of the inlet of the adjustment flow path 6 is the lowest pressure portion, and the pressure gradually recovers toward the downstream side. To do.

  Now, since the gas pressure in the combustion chamber 2 periodically changes, the position of the reattachment point Pc moves to the atmosphere opening side or returns to the inlet side of the adjustment flow path 6. In this situation, when the reattachment point Pc is formed on the most open side of the atmosphere, and the suction position Ps is positioned closer to the inlet side of the adjustment flow path 6 than the reattachment point Pc, the sample gas sg that has flowed backward is obtained. May be sucked into the suction path 8. Therefore, the suction position Ps is a state in which the flow rate of the sample gas flow generated with the pressure fluctuation in the combustion chamber 2 is the maximum flow rate (the state in which the flow rate of the sample gas sg at the inlet of the adjustment flow path 6 is maximum). A suction position Ps to which the suction path 8 is connected is set downstream of the reattachment point Pc of the jet flow ejected from the sample probe 5 to the adjustment flow path 6.

2 Flow path volume from the suction position to the atmospheric release position in the adjustment flow path As described above, FIG. 4A shows the output of the gas analyzer 4 when the sampling device 100 shown in FIG. THC concentration). This result is a case where the volume v1 sucked by the analyzer 4 per engine cycle is larger than the flow path volume v2 from the suction position Ps to the atmosphere open end 6b.

  Now, the inventors of the present application also examined a case where the flow path volume v2 from the suction position Ps to the atmosphere open end 6b is larger than v1 in the examination process of the sampling device 100 according to the present application. In this case, the sample gas sg that has passed through the suction position Ps at a predetermined timing mainly stays in the adjustment flow path 6 on the downstream side of the suction position Ps, and the pressure fluctuation on the combustion chamber 2 side (sample probe 5 is removed). The sample gas sp reciprocates in the direction of the flow path in the adjustment flow path 6 as the sample gas sg periodically flows out.

  FIG. 4B shows the output of the gas analyzer 4 in this situation. As can be seen from this figure, when the adjustment flow path 6 on the downstream side of the suction position Ps is carelessly long, it is preferable that the gas analyzer 4 sucks the sample gas sg that should not be sucked. The result is not obtained. That is, in the sampling apparatus 100 as in the present application, the sample gas sg in the adjustment flow path 6 formed by the pressure fluctuation on the combustion chamber 2 side is selected by appropriately selecting the flow path volume v2 downstream from the suction position Ps. It is necessary to dilute the sample gas sg to some extent by using the respiration (reciprocating motion along the flow path axis in the adjustment flow path 6) to guide the atmosphere into the adjustment flow path.

[Another embodiment]
(1) In the above embodiment, an analyzer capable of detecting THC is adopted as a gas analyzer. However, a gas analyzer that detects any gas component such as an analyzer capable of detecting methane or the like. A total can be adopted.
(2) In the above embodiment, the flow path volume v2 up to the position where the atmosphere is released downstream from the suction position Ps in the adjustment flow path is less than the volume v1 that the gas analyzing means sucks in one cycle time of the engine. Although this example is intended to dilute the sample gas sg originally located downstream of the suction position Ps with the atmosphere, it is set to be less than the volume sucked by the gas analysis means during the intake stroke time of the engine. It is good also as what to do.
(3) In the above embodiment, the suction position Ps is set to a position where the reattachment to the side wall of the jet is completed and further flows downstream, and the pressure is sufficiently recovered. If the capacity is sufficient, new exhaust gas can be sampled without sucking the return flow if it is set downstream from the reattachment point.

  As a sampling device that performs analysis by sampling a sample gas through a sample probe from a gas chamber that repeats pressure fluctuations at a predetermined period, even when the pressure fluctuates greatly in a short time, it performs analysis with good responsiveness A sampling device capable of

The figure which shows the state which is analyzing the sample gas sampled from a combustion chamber using the sampling device which concerns on this application Diagram showing changes in gas pressure in the combustion chamber The figure which shows the change of the flow volume of each site | part of a sampling apparatus when performing a gas analysis using the sampling apparatus which concerns on this application The figure which shows the result of gas analysis using the sampling device shown in FIG. 1 (FIG. 4A), and the figure which shows the result of gas analysis when the flow path volume downstream from the suction position in the adjustment flow path is large ( FIG. 4 (b)) Regarding the sampling device according to the present application, a diagram showing a flow state from the sample probe to the adjustment channel (FIG. 5A), a diagram showing a gas pressure state (FIG. 5B), and a schematic configuration of the channel Figure (Fig. 5 (c))

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Combustion chamber 3 Supercharger 4 Gas analyzer 5 Sample probe 6 Adjustment flow path 7 Sample pump 8 Suction path Fa Jet flow Fb Back flow (return flow)
Pc Reattachment point Ps Suction position

Claims (7)

A sampling apparatus for analyzing a sample gas by introducing a sample gas sampled from a gas chamber that repeats pressure fluctuations at a predetermined cycle via a sample probe to a gas analysis means by a suction means,
One end is connected to the outlet of the sample probe, the other end is opened to the atmosphere, and an adjustment channel having a larger channel cross-sectional area than the sample probe is provided,
By the action of the suction means, a suction path for sucking a sample gas from the adjustment flow path in a direction perpendicular to the adjustment flow path and leading to the gas analysis means,
The suction position of the suction path is set downstream of the reattachment point of the jet flow ejected from the sample probe to the adjustment flow channel in a state where the flow velocity of the sample gas flow generated with the pressure fluctuation becomes the maximum flow velocity. Sampling equipment.   The sampling apparatus according to claim 1, further comprising a step portion that rapidly expands a cross-sectional area of the channel between the sample probe and the adjustment channel.   The sampling apparatus according to claim 1, wherein the suction position is a position where the pressure recovers to an atmospheric pressure due to redevelopment of the sample gas flow downstream from the reattachment point, or a position downstream from the position.   The sampling apparatus according to any one of claims 1 to 3, wherein the gas chamber is a combustion chamber defined by a cylinder and a piston provided in an engine and in which fuel burns.   The flow path volume from the suction position in the adjustment flow path to the position where the atmosphere is opened downstream is set to be less than the volume sucked by the gas analysis means per cycle of the engine. Sampling device.   The flow path volume from the suction position to the position where the atmosphere is opened downstream from the suction position in the adjustment flow path is set to be less than the volume sucked by the gas analysis means during the intake stroke time of the engine. Sampling device.   The sampling method which analyzes the said sample gas using the sampling apparatus as described in any one of Claims 1-6.

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