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JP4447266B2 - Exhaust gas flow measuring device and exhaust gas measuring system using the same - Google Patents

Exhaust gas flow measuring device and exhaust gas measuring system using the same Download PDF

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JP4447266B2
JP4447266B2 JP2003294239A JP2003294239A JP4447266B2 JP 4447266 B2 JP4447266 B2 JP 4447266B2 JP 2003294239 A JP2003294239 A JP 2003294239A JP 2003294239 A JP2003294239 A JP 2003294239A JP 4447266 B2 JP4447266 B2 JP 4447266B2
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exhaust gas
differential pressure
flow rate
gas flow
measuring device
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JP2005062056A (en
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博司 中村
伸太郎 青木
一朗 浅野
二郎 千田
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Horiba Ltd
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Horiba Ltd
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Priority to DE602004004709T priority patent/DE602004004709T2/en
Priority to EP07002436A priority patent/EP1793210A3/en
Priority to EP17157248.0A priority patent/EP3190393A1/en
Priority to EP04019438A priority patent/EP1508788B1/en
Priority to DE17157248.0T priority patent/DE17157248T1/en
Priority to US10/919,925 priority patent/US7110878B2/en
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Description

この発明は、例えば、自動車のエンジンから排出される排ガスの流量を計測するための排ガス流量計測装置およびこれを用いた排ガス計測システムに関する。   The present invention relates to an exhaust gas flow rate measuring device for measuring the flow rate of exhaust gas discharged from an automobile engine and an exhaust gas measurement system using the same.

自動車のエンジンから排出され、排気管などの管内を流れる排ガスの流量を連続測定することができる差圧式流量計の一つとして、ピトー管（Ｐｉｔｏｔ ｔｕｂｅ）式流量計がある。このピトー管式流量計においては、標準状態換算した排ガス流量Ｑ（ｔ）〔ｍ3 ／ｍｉｎ〕は、下記（１）式によって与えられる。

Figure 0004447266
ここで、
α：比例定数
ΔＰ（ｔ）：ピトー管の差圧〔ｋＰａ〕
Ｐ（ｔ）：排ガス圧力〔ｋＰａ〕
Ｔ（ｔ）：排ガス温度〔°Ｋ〕
ρ：標準状態における排ガス密度〔ｇ／ｍ3 〕 One of the differential pressure type flow meters that can continuously measure the flow rate of exhaust gas discharged from an automobile engine and flowing through a pipe such as an exhaust pipe is a Pitot tube type flow meter. In this Pitot tube flow meter, the exhaust gas flow rate Q (t) [m 3 / min] converted to the standard state is given by the following equation (1).
Figure 0004447266
here,
α: Proportional constant ΔP (t): Pitot tube differential pressure [kPa]
P (t): Exhaust gas pressure [kPa]
T (t): exhaust gas temperature [° K]
ρ: exhaust gas density in standard state [g / m 3 ]

すなわち、比例係数αを予め求めておけば、管内を流れる排ガスの温度、圧力、ピトー管の差圧の測定値から、排ガスの流量を得ることができる。   That is, if the proportionality coefficient α is obtained in advance, the flow rate of the exhaust gas can be obtained from the measured values of the temperature, pressure and differential pressure of the Pitot tube flowing in the pipe.

しかし、ピトー管式流量計は、排ガスの脈動時にその影響を受け、差圧から排ガス流量を演算する際に生じるいわゆる平方根誤差により、排ガス流量の測定誤差が大きくなることが指摘されている。   However, it has been pointed out that the Pitot tube type flow meter is affected by the pulsation of the exhaust gas, and the measurement error of the exhaust gas flow rate increases due to a so-called square root error that occurs when calculating the exhaust gas flow rate from the differential pressure.

そこで、特許文献１に示されているように、バッファタンクで排ガスの脈動を抑えつつ、流量計（アニューバ流量計）の差圧センサを用いて排ガス流量を測定する装置が考案されている。   Therefore, as disclosed in Patent Document 1, an apparatus has been devised that measures the exhaust gas flow rate using a differential pressure sensor of a flow meter (annual flow meter) while suppressing the pulsation of the exhaust gas in a buffer tank.

また、特許文献２に示されているように、配管に加工を施し、空間フィルタを構成し脈動周波数を求める装置や、特許文献３に示されているように、超音波流量計を用いて脈動周波数を求める装置が考案されている。
特開平１０−３１８８１０号公報 特開２０００−４６６１２号公報 特開２００１−２０８５８４号公報 Further, as shown in Patent Document 2, a pipe is processed to form a spatial filter to obtain a pulsation frequency, and as disclosed in Patent Document 3, an ultrasonic flowmeter is used to pulsate. Devices for determining the frequency have been devised.
Japanese Patent Laid-Open No. 10-318810 JP 2000-46612 A JP 2001-208584 A

しかし、特許文献１に示される排ガス流量測定装置では、排ガスの脈動をバッファタンクで吸収することにより測定場を変化させてしまい、ありのまま（ｉｎ−ｓｉｔｕ）で測定することができない。これは、脈動そのものの解明やトランジェント計測が求められる現状及び今後の方向性にそぐわない。しかも、バッファタンクによって排ガスの脈動を完全に取り除くことは困難であることに加えて、可変容量のバッファタンクを形成したり、エンジン回転数にあわせてバッファタンクの容量を変える機構を設ける必要があるなど、装置自体が大掛かりで複雑なものにならざるを得ない。また、特許文献２に示されるガス流の測定装置および特許文献３に示される流量測定装置でも、装置自体が大掛かりで複雑なものになるといった不都合がある。   However, in the exhaust gas flow rate measuring device disclosed in Patent Document 1, the measurement field is changed by absorbing the pulsation of the exhaust gas with the buffer tank, and the measurement cannot be performed in-situ. This is inconsistent with the current situation and future directions where pulsation itself and transient measurement are required. Moreover, it is difficult to completely remove the pulsation of the exhaust gas by the buffer tank, and it is necessary to form a variable capacity buffer tank or to provide a mechanism for changing the capacity of the buffer tank according to the engine speed. The device itself must be large and complicated. Further, the gas flow measuring device shown in Patent Document 2 and the flow rate measuring device shown in Patent Document 3 also have the disadvantage that the device itself is large and complicated.

ところで、ピトー管式流量計では、上記（１）式に示すように、排ガス流量と差圧の平方根とが比例関係にあることを利用して排ガス流量を算出するので、差圧と排ガス流量とは、図７のグラフで示される関係を有することとなる。なお、図７において、横軸には差圧〔ｋＰａ〕、縦軸には流量〔Ｌ／ｍｉｎ〕がとられている。そして、本発明者らは、排ガスの脈動に伴って、差圧が経時的に変化し、例えば、図７においてａで示すように脈動したときに、ピトー管の差圧を検出する差圧センサの応答周波数が低いと、差圧の測定値は平均化され、この平均化された差圧の測定値（例えば図７では約１．４〔ｋＰａ〕）に対応する排ガス流量（図７では約１３００〔Ｌ／ｍｉｎ〕）が得られ、このようにして得られた排ガス流量は、差圧を排ガス流量に変換した後に平均化して得られる正確な排ガス流量（図７では約１１５０〔Ｌ／ｍｉｎ〕）と比べて、高い値となるということを発見した。   By the way, in the Pitot tube type flow meter, as shown in the above equation (1), the exhaust gas flow rate is calculated by utilizing the proportional relationship between the exhaust gas flow rate and the square root of the differential pressure. Will have the relationship shown in the graph of FIG. In FIG. 7, the horizontal axis represents differential pressure [kPa], and the vertical axis represents flow rate [L / min]. Then, the present inventors have developed a differential pressure sensor that detects the differential pressure of the Pitot tube when the differential pressure changes with time as the exhaust gas pulsates, for example, as shown by a in FIG. When the response frequency is low, the measured value of the differential pressure is averaged, and the exhaust gas flow rate corresponding to the averaged measured value of the differential pressure (for example, about 1.4 [kPa] in FIG. 7) is about 1300 [L / min]) is obtained, and the exhaust gas flow rate obtained in this way is an accurate exhaust gas flow rate obtained by averaging after converting the differential pressure to the exhaust gas flow rate (in FIG. 7, about 1150 [L / min]). )) And found a higher value.

この発明は上述の事柄に留意してなされたもので、その目的は、エンジンから排出される排ガスの流量を、脈動等が発生した場合にもリアルタイムで精度良く、しかも測定場を変化させることなく計測することができ、ひいては容易に小型化を図ることが可能な排ガス流量計測装置およびこれを用いた排ガス計測システムを提供することである。   The present invention has been made in consideration of the above-mentioned matters. The purpose of the present invention is to accurately control the flow rate of exhaust gas discharged from an engine in real time even when pulsation or the like occurs without changing the measurement field. It is an object to provide an exhaust gas flow rate measuring device that can be measured and can be easily reduced in size, and an exhaust gas measurement system using the exhaust gas flow rate measuring device.

上記目的を達成するために、この発明の排ガス流量計測装置は、エンジンから排出された排ガスが流れる流路にそれぞれ設けられる全圧検出部および静圧検出部と、全圧検出部および静圧検出部が接続される差圧センサと、演算処理装置とを備え、前記差圧センサが、排ガスの脈動周波数以上の応答周波数で静圧と全圧との差圧を検出して差圧信号を前記演算処理装置に出力する高速応答型差圧センサであり、該演算処理装置は前記差圧信号が示す差圧の瞬時値を用い、排ガス流量を導出する演算の周波数が前記脈動周波数以上になるように排ガス流量を算出するように構成してある（請求項１）。 In order to achieve the above object, an exhaust gas flow rate measuring device according to the present invention comprises a total pressure detection unit and a static pressure detection unit, a total pressure detection unit and a static pressure detection respectively provided in a flow path through which exhaust gas discharged from an engine flows. A differential pressure sensor to which a part is connected, and an arithmetic processing unit, wherein the differential pressure sensor detects a differential pressure between a static pressure and a total pressure at a response frequency equal to or higher than a pulsation frequency of exhaust gas, and outputs the differential pressure signal a high-speed response type differential pressure sensor to be output to the processing unit, the said processing unit using the instantaneous value of the differential pressure indicated by the differential pressure signal, so that the frequency of operation for deriving the exhaust gas flow rate becomes equal to or higher than the pulse frequency The exhaust gas flow rate is calculated as follows (claim 1).

また、この発明の排ガス流量計測装置は、エンジンから排出された排ガスが流れる流路にそれぞれ設けられる全圧検出部および静圧検出部と、全圧検出部および静圧検出部が接続される差圧センサと、演算処理装置とを備え、前記差圧センサが、エンジンがアイドル状態のときの排ガスの脈動周波数以上の応答周波数で静圧と全圧との差圧を検出して差圧信号を前記演算処理装置に出力する高速応答型差圧センサであり、該演算処理装置は前記差圧信号が示す差圧の瞬時値を用い、排ガス流量を導出する演算の周波数が前記脈動周波数以上になるように排ガス流量を算出するように構成してある（請求項２）。 Further, the exhaust gas flow rate measuring device of the present invention includes a difference between the total pressure detection unit and the static pressure detection unit, and the total pressure detection unit and the static pressure detection unit provided in the flow path through which the exhaust gas discharged from the engine flows. A pressure sensor and an arithmetic processing unit, wherein the differential pressure sensor detects a differential pressure signal between a static pressure and a total pressure at a response frequency equal to or higher than a pulsation frequency of exhaust gas when the engine is in an idle state, and generates a differential pressure signal. a high-speed response type differential pressure sensor to be output to the processing unit, the said processing unit using the instantaneous value of the differential pressure indicated by the differential pressure signal, the frequency of operation for deriving the exhaust gas flow rate becomes equal to or higher than the pulse frequency In this way, the exhaust gas flow rate is calculated (claim 2).

差圧センサが、半導体差圧センサであるのが好ましい（請求項３）。   The differential pressure sensor is preferably a semiconductor differential pressure sensor.

全圧検出部と差圧センサとの間および／または静圧検出部と差圧センサとの間に、応答差調整機構を設けてもよい（請求項４）。   A response difference adjusting mechanism may be provided between the total pressure detection unit and the differential pressure sensor and / or between the static pressure detection unit and the differential pressure sensor.

応答差調整機構が、バッファタンクまたはキャピラリまたは絞り弁であるとしてもよい（請求項５）。   The response difference adjusting mechanism may be a buffer tank, a capillary, or a throttle valve.

全圧検出部と差圧センサとの間および／または静圧検出部と差圧センサとの間に連通部が設けられており、この連通部が、２０ｍ以下の長さを有し、１．０〜５０ｍｍの内径を有する配管により構成されていてもよい（請求項６）。   A communication part is provided between the total pressure detection part and the differential pressure sensor and / or between the static pressure detection part and the differential pressure sensor, and the communication part has a length of 20 m or less. You may be comprised by piping which has an internal diameter of 0-50 mm (Claim 6).

差圧信号が示す差圧の平方根と排ガス流量とが比例することに基づいて排ガス流量を演算し、差圧信号が示す差圧が負であるときには、差圧信号が示す差圧の絶対値の平方根に−１を乗じた値と排ガス流量とが比例することに基づいて排ガス流量を演算するように構成されているのが好ましい（請求項７）。
すなわち、式（１）において、ΔＰ＜０のときは、式（１）を下記の式（２）に代える。

Figure 0004447266
ここで、
α’：比例定数
｜ΔＰ（ｔ）｜：ピトー管の差圧の絶対値〔ｋＰａ〕 The exhaust gas flow rate is calculated based on the fact that the square root of the differential pressure indicated by the differential pressure signal is proportional to the exhaust gas flow rate, and when the differential pressure indicated by the differential pressure signal is negative, the absolute value of the differential pressure indicated by the differential pressure signal is calculated. It is preferable that the exhaust gas flow rate be calculated based on the fact that the value obtained by multiplying the square root by -1 and the exhaust gas flow rate are proportional to each other (Claim 7).
That is, in the equation (1), when ΔP <0, the equation (1) is replaced with the following equation (2).
Figure 0004447266
here,
α ′: proportionality constant | ΔP (t) |: absolute value of differential pressure of pitot tube [kPa]

差圧信号が示す差圧を、流量に変換した後、平均化することにより排ガスの平均流量を求めるように構成されているのが好ましい（請求項８）。   The differential pressure indicated by the differential pressure signal is preferably converted to a flow rate and then averaged to obtain the average flow rate of the exhaust gas (claim 8).

車載タイプとしてもよい（請求項９）。   It may be a vehicle-mounted type (claim 9).

そして、上記目的を達成するために、この発明の排ガス計測システムは、請求項１〜９のいずれかに記載の排ガス流量計測装置を備えた（請求項１０）。   And in order to achieve the said objective, the exhaust gas measurement system of this invention was equipped with the exhaust gas flow measuring device in any one of Claims 1-9 (Claim 10).

請求項１および２に係る発明によれば、エンジンから排出される排ガスの流量を、脈動等が発生した場合にもリアルタイムで精度良く、しかも測定場を変化させることなく計測することができ、ひいては容易に小型化を図ることが可能な排ガス流量計測装置が得られる。   According to the first and second aspects of the invention, the flow rate of the exhaust gas discharged from the engine can be measured in real time with high accuracy even when pulsation or the like occurs, and without changing the measurement field. An exhaust gas flow rate measuring device that can be easily downsized is obtained.

詳しくは、例えば、排ガスの脈動時に差圧を検出する差圧センサの応答周波数が脈動周波数よりも低い場合には、上述したように、検出される差圧が平均化されて測定誤差が大きくなるが、請求項１および２に係る発明では、排ガスの脈動周波数以上の応答周波数で静圧と全圧との差圧を検出するように構成してあるので、検出される差圧の平均化が抑えられ、従って、排ガスの流量が精度良く計測されることとなる。   Specifically, for example, when the response frequency of the differential pressure sensor that detects the differential pressure when the exhaust gas pulsates is lower than the pulsation frequency, the detected differential pressure is averaged and the measurement error increases as described above. However, in the inventions according to claims 1 and 2, since the differential pressure between the static pressure and the total pressure is detected at a response frequency equal to or higher than the pulsation frequency of the exhaust gas, the detected differential pressure is averaged. Therefore, the flow rate of the exhaust gas is accurately measured.

また、請求項１および２に係る発明では、バッファタンクなどを用いて排ガスの脈動を抑えず、測定場を変化させることなくありのままで排ガス流量を計測することができる。   In the inventions according to claims 1 and 2, it is possible to measure the exhaust gas flow rate without changing the measurement field without suppressing the pulsation of the exhaust gas using a buffer tank or the like.

さらに、請求項１および２に係る発明は、例えば、一般的に用いられているピトー管と、応答周波数が脈動周波数以上である差圧センサとで主要な部分を構成することができ、ピトー管は小型かつコンパクトであり、また、差圧センサもエッチキャビティなどによって小型化したものを用いることができるので、装置全体の小型化を容易に図ることが可能である。   Further, in the invention according to claims 1 and 2, for example, a principal part can be constituted by a pitot tube that is generally used and a differential pressure sensor having a response frequency equal to or higher than a pulsation frequency. Is small and compact, and a differential pressure sensor that is downsized by an etch cavity or the like can be used. Therefore, the entire apparatus can be easily downsized.

請求項３に記載したように、差圧センサを半導体差圧センサとした場合には、より容易に小型化を図ることが可能となる。   As described in claim 3, when the differential pressure sensor is a semiconductor differential pressure sensor, the size can be more easily reduced.

請求項４に記載のように、応答差調整機構を設けた場合には、差圧センサが検出する全圧と静圧との応答時間が異なることによって生じる誤差を無くすことができる。   According to the fourth aspect of the present invention, when the response difference adjusting mechanism is provided, it is possible to eliminate an error caused by a difference in response time between the total pressure detected by the differential pressure sensor and the static pressure.

請求項５に記載したように、応答差調整機構をバッファタンクまたはキャピラリまたは絞り弁とした場合には、応答差調整機構がシンプルな構成を有し、かつ安価なものとなる。   In the case where the response difference adjusting mechanism is a buffer tank, capillary or throttle valve, the response difference adjusting mechanism has a simple configuration and is inexpensive.

請求項６に記載したように、連通部を、２０ｍ以下で、１．０〜５０ｍｍの内径を有する配管により構成した場合には、連通部によって脈動による差圧が緩衝されることを確実に防止することができる。   As described in claim 6, when the communication portion is constituted by a pipe having an inner diameter of 1.0 to 50 mm with a length of 20 m or less, the communication portion reliably prevents the differential pressure due to pulsation from being buffered. can do.

請求項７に記載したように、差圧信号が示す差圧が負であるときには、差圧信号が示す差圧の絶対値の平方根に−１を乗じた値と排ガス流量とが比例することに基づいて排ガス流量を演算する場合には、排ガスの流路内において発生した逆流を正確に排ガス流量として導出することができ、排ガス流量の測定の信頼性が向上することとなる。   As described in claim 7, when the differential pressure indicated by the differential pressure signal is negative, the value obtained by multiplying the square root of the absolute value of the differential pressure indicated by the differential pressure signal by -1 is proportional to the exhaust gas flow rate. When the exhaust gas flow rate is calculated based on this, the backflow generated in the exhaust gas flow path can be accurately derived as the exhaust gas flow rate, and the reliability of the exhaust gas flow rate measurement is improved.

請求項８に記載したように、差圧信号が示す差圧を、流量に変換した後、平均化することにより排ガスの平均流量を求めれば、排ガス流量の測定値がより精度の高いものとなる。   If the average flow rate of the exhaust gas is obtained by converting the differential pressure indicated by the differential pressure signal into the flow rate and then averaging it as described in claim 8, the measured value of the exhaust gas flow rate becomes more accurate. .

請求項９に記載したように、この発明の排ガス流量計測装置を車載タイプとした場合には、例えば、シャシダイナモ上で模擬的に走行させる自動車からの排ガス流量のみならず、実際の走行時の自動車からの排ガス流量をも測定することができ、排ガス流量についてより有用なデータを採取することが可能となる。   As described in claim 9, when the exhaust gas flow rate measuring device of the present invention is an in-vehicle type, for example, not only exhaust gas flow rate from an automobile that runs on a chassis dynamometer, but also during actual travel. The exhaust gas flow rate from the automobile can also be measured, and more useful data can be collected about the exhaust gas flow rate.

請求項１０に係る発明では、ミニダイリュータ法を利用して排ガスの一部を高精度で再現性良くサンプリングすることができ、しかも排ガスの各成分の濃度だけではなく質量をも精度良く算出することができる排ガス計測システムを提供することができる。すなわち、請求項１０に係る排ガス計測システムは、請求項１〜９に係る排ガス流量計測装置を備えているので、排ガス流量計測装置によって精度の高い排ガス流量の測定値がリアルタイムで得られ、この排ガス流量の測定値は、例えば、リアルタイムの正確な排ガス流量の測定値を必要とするミニダイリュータ法や、排ガスの濃度から質量を導出する際にリアルタイムの正確な排ガス流量の測定値を必要とするガス分析計などに効果的に利用することができる。   In the invention according to claim 10, a part of the exhaust gas can be sampled with high accuracy and reproducibility using the mini-diluter method, and not only the concentration of each component of the exhaust gas but also the mass can be calculated accurately. It is possible to provide an exhaust gas measurement system that can That is, since the exhaust gas measurement system according to claim 10 includes the exhaust gas flow measurement device according to claims 1 to 9, a highly accurate measurement value of the exhaust gas flow rate can be obtained in real time by the exhaust gas flow measurement device. For example, the measurement value of the flow rate requires a real-time accurate measurement value of the exhaust gas flow when the mass is derived from the concentration of the exhaust gas. It can be effectively used for gas analyzers.

図１および図２は、この発明の一実施例を示す。   1 and 2 show an embodiment of the present invention.

図１に示すように、この実施例の排ガス計測システムＳは、自動車１のエンジン（図示していない）から排出された排ガスＧの流路２中に設けられ、前記排ガスＧの流量を計測する排ガス流量計測装置Ｄ（詳細は後述する）と、サンプルバッグ３と、流路２を流れる排ガスＧの一部を一定比率で希釈し、これを前記排ガス流量計測装置Ｄにより計測された排ガスＧの流量に比例した流量でサンプルバッグ３に採取させるためのミニダイリュータ４と、このミニダイリュータ４に排ガスＧを希釈する希釈ガス（この実施例ではＮ2 ）Ｋを供給するための希釈ガス供給源５と、サンプルバッグ３に接続され、サンプルバッグ３に捕集された排ガスＧ中の所定成分（例えば、ＨＣ，ＣＯ，Ｈ2 Ｏ，ＮＯX など）を分析するガス分析計Ａとを有する。 As shown in FIG. 1, the exhaust gas measurement system S of this embodiment is provided in a flow path 2 of exhaust gas G discharged from an engine (not shown) of an automobile 1 and measures the flow rate of the exhaust gas G. Exhaust gas flow rate measuring device D (details will be described later), sample bag 3, and a part of exhaust gas G flowing through flow path 2 are diluted at a constant ratio, and this is diluted with exhaust gas flow rate measuring device D. A mini-diluter 4 for collecting the sample bag 3 at a flow rate proportional to the flow rate, and a dilution gas supply for supplying a dilution gas (N 2 ) K for diluting the exhaust gas G to the mini-diluter 4 A source 5 and a gas analyzer A that is connected to the sample bag 3 and analyzes predetermined components (for example, HC, CO, H 2 O, NO x, etc.) in the exhaust gas G collected in the sample bag 3 .

なお、希釈ガス供給源５は、例えば、希釈ガスを収容した高圧ボンベからなる。また、ガス分析計Ａは、例えば、非分散型赤外分光法（ＮＤＩＲ）型ガス分析計である。   The dilution gas supply source 5 is composed of, for example, a high-pressure cylinder that stores dilution gas. The gas analyzer A is, for example, a non-dispersive infrared spectroscopy (NDIR) type gas analyzer.

以下、ミニダイリュータ４について説明する。   Hereinafter, the mini-diluter 4 will be described.

ミニダイリュータ４は、流路２に上流端が接続され、途中にポンプ６を有するサンプルガス流路７と、上流端が希釈ガス供給源５に接続され、下流端がサンプルガス流路７に接続される希釈ガス流路８と、上流端がサンプルガス流路７における希釈ガス流路８の接続点よりも下流側の位置に接続され、下流端がサンプルバッグ３に接続されるサンプルガス採取ライン９とを備えている。   The mini diluter 4 has an upstream end connected to the flow path 2, a sample gas flow path 7 having a pump 6 in the middle, an upstream end connected to the dilution gas supply source 5, and a downstream end connected to the sample gas flow path 7. Sample gas sampling in which the dilution gas flow path 8 to be connected and the upstream end are connected to a position downstream of the connection point of the dilution gas flow path 8 in the sample gas flow path 7 and the downstream end is connected to the sample bag 3 Line 9.

サンプルガス流路７は、流路２内に挿入され、流路２内を流れる排ガスＧの一部を採取するためのサンプリングプローブ（図示していない）を上流端に有している。また、サンプルガス流路７における希釈ガス流路８の接続点よりも上流側の位置には、臨界流量ベンチュリ（ＣＦＶ）１０が設けられている。   The sample gas flow path 7 is inserted into the flow path 2 and has a sampling probe (not shown) for collecting a part of the exhaust gas G flowing in the flow path 2 at the upstream end. A critical flow venturi (CFV) 10 is provided at a position upstream of the connection point of the dilution gas flow path 8 in the sample gas flow path 7.

なお、詳細は後述するが、この実施例の流路２は、図２に示すように、排気管１４とテールパイプアタッチメント１５とによって構成され、上述したサンプルガス流路７のサンプリングプローブは、テールパイプアタッチメント１５内に挿入されるが、図２では省略している。   Although details will be described later, the flow channel 2 of this embodiment is constituted by an exhaust pipe 14 and a tail pipe attachment 15 as shown in FIG. 2, and the sampling probe of the sample gas flow channel 7 described above is a tail. Although inserted in the pipe attachment 15, it is omitted in FIG.

希釈ガス流路８には、上流側から順に、レギュレータ１１と、臨界流量ベンチュリ（ＣＦＶ）１２とが設けられている。そして、レギュレータ１１によって、サンプルガス流路７を流れる排ガスＧの流量と希釈ガス流路８を流れる希釈ガスＫの流量との比が常に一定となるように調整され、希釈ガス流路８からサンプルガス流路７に流れ込む希釈ガスＫによって、サンプルガス流路７を流れる排ガスＧは一定比率で希釈される。   The dilution gas flow path 8 is provided with a regulator 11 and a critical flow venturi (CFV) 12 in order from the upstream side. The regulator 11 adjusts the ratio of the flow rate of the exhaust gas G flowing through the sample gas flow channel 7 and the flow rate of the dilution gas K flowing through the dilution gas flow channel 8 to be always constant. The exhaust gas G flowing through the sample gas channel 7 is diluted at a constant ratio by the dilution gas K flowing into the gas channel 7.

サンプルガス採取ライン９は、サンプルガス流路７において希釈ガスＫによって一定比率で希釈された排ガスＧの一部を、サンプルバッグ３に採取させるためのものである。このサンプルガス採取ライン９には、マスフローコントローラ（ＭＦＣ）１３が設けられており、ＭＦＣ１３には、流路２を流れる排ガスＧの流量の計測値が、排ガス流量計測装置Ｄから出力信号ｇとしてフィードバックされる。そして、希釈ガスＫによって一定比率で希釈された排ガスＧのサンプルバッグ３への採取流量は、ＭＦＣ１３により、流路２を流れる排ガスＧの流量の計測値に比例するように制御される。   The sample gas collection line 9 is for causing the sample bag 3 to collect a part of the exhaust gas G diluted with the dilution gas K at a constant ratio in the sample gas flow path 7. The sample gas collection line 9 is provided with a mass flow controller (MFC) 13, and the measured value of the flow rate of the exhaust gas G flowing through the flow path 2 is fed back as an output signal g from the exhaust gas flow rate measuring device D to the MFC 13. Is done. The sampling flow rate of the exhaust gas G diluted with the dilution gas K at a certain ratio is controlled by the MFC 13 to be proportional to the measured value of the flow rate of the exhaust gas G flowing through the flow path 2.

以下、排ガス流量計測装置Ｄについて説明する。   Hereinafter, the exhaust gas flow rate measuring device D will be described.

図２に示すように、排ガス流量計測装置Ｄは、車載タイプとして構成されており、詳しくは、自動車１の排気管１４の下流端部に着脱自在に接続され、流路２を構成するテールパイプアタッチメント１５と、このテールパイプアタッチメント１５内を流れる排ガスＧの流量を計測するための差圧式流量計１６と、この差圧式流量計１６からの出力信号が入力される演算処理装置（例えばパソコン）１７とを備え、差圧式流量計１６および演算処理装置１７はユニット構成された状態でテールパイプアタッチメント１５に取り付けられる。   As shown in FIG. 2, the exhaust gas flow rate measuring device D is configured as an in-vehicle type. Specifically, the tail pipe is detachably connected to the downstream end portion of the exhaust pipe 14 of the automobile 1 and constitutes the flow path 2. An attachment 15, a differential pressure type flow meter 16 for measuring the flow rate of the exhaust gas G flowing through the tail pipe attachment 15, and an arithmetic processing device (for example, a personal computer) 17 to which an output signal from the differential pressure type flow meter 16 is input. The differential pressure type flow meter 16 and the arithmetic processing unit 17 are attached to the tail pipe attachment 15 in a unit configuration.

テールパイプアタッチメント１５は、排気管１４と同等の内径を有するほぼ筒状（円筒状）の部材であり、その一端側には、排気管１４の下流端部に着脱自在に外嵌される接続部１５ａが形成され、他端側は開放されている。   The tail pipe attachment 15 is a substantially cylindrical (cylindrical) member having an inner diameter equivalent to that of the exhaust pipe 14, and at one end side thereof, a connection portion that is detachably fitted to the downstream end portion of the exhaust pipe 14. 15a is formed, and the other end side is open.

差圧式流量計１６は、排ガスＧが流れるテールパイプアタッチメント１５の全圧（静圧＋動圧）と静圧との差圧をピトー管２０（詳細は後述する）によって検出するピトー管式流量計である。詳しくは、差圧式流量計１６は、テールパイプアタッチメント１５にそれぞれ設けられる全圧検出部１８および静圧検出部１９を有するピトー管２０と、全圧検出部１８が第１連通部２１を介して接続され、静圧検出部１９が第２連通部２２を介して接続される差圧センサ２３と、テールパイプアタッチメント１５に設けられ、テールパイプアタッチメント１５内を流れる排ガスＧの温度および圧力を測定するための温度センサ２４および圧力センサ２５とを備えている。   The differential pressure type flow meter 16 detects a differential pressure between the total pressure (static pressure + dynamic pressure) of the tail pipe attachment 15 through which the exhaust gas G flows and a static pressure by a pitot tube 20 (details will be described later). It is. Specifically, the differential pressure type flow meter 16 includes a Pitot tube 20 having a total pressure detection unit 18 and a static pressure detection unit 19 provided in the tail pipe attachment 15, and the total pressure detection unit 18 via the first communication unit 21. Connected and the differential pressure sensor 23 to which the static pressure detection unit 19 is connected via the second communication unit 22 and the tail pipe attachment 15, and measures the temperature and pressure of the exhaust gas G flowing through the tail pipe attachment 15. A temperature sensor 24 and a pressure sensor 25 are provided.

ピトー管２０は、全圧検出部１８としての全圧検出用ピトー管の外側に静圧検出部１９としての静圧検出用ピトー管を配置した二重管構造をしている。また、ピトー管２０は、ほぼＬ字型形状に屈曲しており、テールパイプアタッチメント１５内においてその軸方向とほぼ平行に配置される平行部分２０ａと、この平行部分２０ａに対して垂直に連設され、テールパイプアタッチメント１５の側壁を貫通するように配置される垂直部分２０ｂとを先端側からこの順で有している。   The Pitot tube 20 has a double tube structure in which a static pressure detection Pitot tube as a static pressure detection unit 19 is arranged outside a total pressure detection Pitot tube as the total pressure detection unit 18. The Pitot tube 20 is bent in a substantially L-shape, and a parallel portion 20a disposed substantially parallel to the axial direction in the tail pipe attachment 15 is provided so as to be perpendicular to the parallel portion 20a. The vertical portion 20b is disposed in this order from the front end side so as to penetrate the side wall of the tail pipe attachment 15.

全圧検出用ピトー管１８の平行部分２０ａは、テールパイプアタッチメント１５内を流れる排ガスＧの上流側（図２では左側）に向けて設けられており、その先端には開口１８ａが形成されている。   The parallel portion 20a of the total pressure detecting pitot tube 18 is provided toward the upstream side (left side in FIG. 2) of the exhaust gas G flowing through the tail pipe attachment 15, and an opening 18a is formed at the tip thereof. .

静圧検出用ピトー管１９の平行部分２０ａの側壁には、テールパイプアタッチメント１５内における排ガスＧの流れ方向と垂直となるように貫通孔１９ａが形成されている。また、静圧検出用ピトー管１９の平行部分２０ａの先端と全圧検出用ピトー管１８の平行部分２０ａの先端との間は閉塞してある。   A through hole 19 a is formed in the side wall of the parallel portion 20 a of the static pressure detection pitot tube 19 so as to be perpendicular to the flow direction of the exhaust gas G in the tail pipe attachment 15. Further, the space between the tip of the parallel portion 20a of the static pressure detecting Pitot tube 19 and the tip of the parallel portion 20a of the total pressure detecting Pitot tube 18 is closed.

第１連通部２１および第２連通部２２はそれぞれ、１０ｍ以下の長さを有し、２．０〜５０ｍｍの内径を有する配管により構成されている。また、第１連通部２１および第２連通部２２にはそれぞれ、差圧センサ２３における全圧と静圧との応答差をなくすための応答差調整機構２６としての絞り弁（ニードル弁）が設けられている。   The 1st communication part 21 and the 2nd communication part 22 are respectively comprised by piping which has a length of 10 m or less, and has an internal diameter of 2.0-50 mm. Further, each of the first communication portion 21 and the second communication portion 22 is provided with a throttle valve (needle valve) as a response difference adjusting mechanism 26 for eliminating a response difference between the total pressure and the static pressure in the differential pressure sensor 23. It has been.

差圧センサ２３は、例えば、半導体差圧センサであり、この実施例の差圧センサ２３は、自動車１のエンジンがアイドル状態のときの排ガスＧの脈動周波数（例えば約２０〔Ｈｚ〕）以上（好ましくは４〜５倍以上）の応答周波数で静圧と全圧との差圧を検出して差圧信号を演算処理装置１７に出力するように構成された高速応答型差圧センサである。   The differential pressure sensor 23 is, for example, a semiconductor differential pressure sensor. The differential pressure sensor 23 of this embodiment is equal to or higher than the pulsation frequency (for example, about 20 [Hz]) of the exhaust gas G when the engine of the automobile 1 is in an idle state. It is a high-speed response type differential pressure sensor configured to detect a differential pressure between the static pressure and the total pressure at a response frequency of preferably 4 to 5 times and output a differential pressure signal to the arithmetic processing unit 17.

詳しくは、差圧センサ２３は、第１連通部２１を介して全圧検出部１８に連通する全圧導入部２７と、第２連通部２２を介して静圧検出部１９に連通する静圧導入部２８と、全圧導入部２７および静圧導入部２８の間に配置されるダイヤフラム２９と、このダイヤフラム２９の近傍に配置される歪検出センサ３０とを備えている。   Specifically, the differential pressure sensor 23 includes a total pressure introduction unit 27 that communicates with the total pressure detection unit 18 through the first communication unit 21 and a static pressure that communicates with the static pressure detection unit 19 through the second communication unit 22. An introduction unit 28, a diaphragm 29 disposed between the total pressure introduction unit 27 and the static pressure introduction unit 28, and a strain detection sensor 30 disposed in the vicinity of the diaphragm 29 are provided.

全圧導入部２７は、シリコン基板３１を貫通するようにその厚さ方向に設けられており、静圧導入部２８は、シリコン基板３２を貫通するようにその厚さ方向に設けられている。また、ダイヤフラム２９は、２つのシリコン基板３１，３２に挟まれるシリコン層３３に対してエッチングによって形成した例えば厚さが５０μｍ程度の薄膜化した部分からなる。すなわち、この実施例の差圧センサ２３は、エッチキャビティによりダイヤフラム２９を小型化することによって高い応答周波数をもつようにした拡散型歪みゲージ式差圧計でもある。なお、ダイヤフラム２９の径は適宜に設定される。   The total pressure introducing portion 27 is provided in the thickness direction so as to penetrate the silicon substrate 31, and the static pressure introducing portion 28 is provided in the thickness direction so as to penetrate the silicon substrate 32. The diaphragm 29 is formed of a thinned portion having a thickness of, for example, about 50 μm formed by etching the silicon layer 33 sandwiched between the two silicon substrates 31 and 32. That is, the differential pressure sensor 23 of this embodiment is also a diffusion type strain gauge type differential pressure gauge that has a high response frequency by downsizing the diaphragm 29 by an etch cavity. The diameter of the diaphragm 29 is set appropriately.

上記の構成からなる差圧センサ２３では、全圧検出部１８によって検出された全圧と静圧検出部１９によって検出された静圧との圧力差（差圧）に応じてダイヤフラム２９が歪み、この歪み量が歪検出センサ３０によって電気的に検出され、圧力差を示す差圧信号が歪検出センサ３０から演算処理装置１７へと送られることとなる。   In the differential pressure sensor 23 configured as described above, the diaphragm 29 is distorted in accordance with the pressure difference (differential pressure) between the total pressure detected by the total pressure detection unit 18 and the static pressure detected by the static pressure detection unit 19, This strain amount is electrically detected by the strain detection sensor 30, and a differential pressure signal indicating a pressure difference is sent from the strain detection sensor 30 to the arithmetic processing unit 17.

温度センサ２４、圧力センサ２５は、流路２を流れる排ガスＧの温度、圧力の測定値を温度信号および圧力信号としてそれぞれ演算処理装置１７へと送る。   The temperature sensor 24 and the pressure sensor 25 send the measured values of the temperature and pressure of the exhaust gas G flowing through the flow path 2 to the arithmetic processing unit 17 as temperature signals and pressure signals, respectively.

演算処理装置１７は、差圧式流量計１６とともにケース３４内に収容された状態でテールパイプアタッチメント１５に着脱自在に取り付けられ、差圧センサ２３、温度センサ２４および圧力センサ２５の出力信号が入力され、これらの信号を用いて上記（１）式に示す演算を行って排ガス流量の測定値を算出し、この測定値を出力信号ｇとしてミニダイリュータ４のＭＦＣ１３に送る。   The arithmetic processing unit 17 is detachably attached to the tail pipe attachment 15 while being accommodated in the case 34 together with the differential pressure type flow meter 16, and output signals of the differential pressure sensor 23, the temperature sensor 24 and the pressure sensor 25 are input thereto. Using these signals, the calculation shown in the above equation (1) is performed to calculate the measured value of the exhaust gas flow rate, and this measured value is sent as an output signal g to the MFC 13 of the minidiluter 4.

また、演算処理装置１７において求められた排ガス流量の測定値をガス分析計Ａに送り、ガス分析計Ａにおいて測定された排ガスＧ中のＨＣ，ＣＯ，Ｈ2 Ｏ，ＮＯX などの各成分の濃度に掛け合わせることにより、各成分の排出量を求めることができる。 Further, the measured value of the exhaust gas flow rate obtained in the arithmetic processing unit 17 is sent to the gas analyzer A, and each component such as HC, CO, H 2 O, NO X in the exhaust gas G measured in the gas analyzer A is measured. By multiplying the concentration, the discharge amount of each component can be obtained.

上記の構成からなる排ガス流量計測装置Ｄでは、流路２を流れる排ガスＧが脈動し、瞬間的にダイナミックに変化しても、排ガスＧの差圧を正確に計測することができ、正確な排ガス流量の測定値を導出することができる。   In the exhaust gas flow rate measuring device D configured as described above, even if the exhaust gas G flowing through the flow path 2 pulsates and changes instantaneously dynamically, the differential pressure of the exhaust gas G can be accurately measured, and the accurate exhaust gas A measurement of the flow rate can be derived.

すなわち、排ガスＧの脈動に伴って生じる排ガス流量の測定誤差の主な原因としては、差圧センサ２３の応答周波数が低く、正確な差圧の測定値ではなく、平均化された差圧の測定値が流量演算に用いられてしまうこと（振幅誤差）と、差圧センサ２３が検出する全圧と静圧との応答時間が異なること（位相誤差）とが挙げられる。   That is, the main cause of the measurement error of the exhaust gas flow rate caused by the pulsation of the exhaust gas G is that the response frequency of the differential pressure sensor 23 is low and the measured differential pressure is not an accurate measured value but an averaged differential pressure. The value is used for the flow rate calculation (amplitude error), and the response time between the total pressure detected by the differential pressure sensor 23 and the static pressure is different (phase error).

そして、この実施例の排ガス流量計測装置Ｄでは、排ガスＧの脈動周波数以上の応答周波数で静圧と全圧との差圧を検出するように構成してあるので、検出される差圧の平均化が抑えられ、従って、上述した振幅誤差を非常に小さくするあるいは無くすことができる。例えば、サンプリング（標本化）定理により、差圧の原波形は、差圧センサ２３の応答周波数が脈動周波数の２倍以上であれば再現される。   In the exhaust gas flow rate measuring device D of this embodiment, since the differential pressure between the static pressure and the total pressure is detected with a response frequency equal to or higher than the pulsation frequency of the exhaust gas G, the average of the detected differential pressures Therefore, the amplitude error described above can be greatly reduced or eliminated. For example, according to the sampling (sampling) theorem, the original waveform of the differential pressure is reproduced if the response frequency of the differential pressure sensor 23 is twice or more the pulsation frequency.

上記のことを確認するためにコンピュータを用いてシミュレーションを行った。このシミュレーションは、応答周波数が２０００〔Ｈｚ〕の差圧センサ２３を用いて、脈動周波数が２２〔Ｈｚ〕である排ガスＧを実測して得られた排ガス流量を基準にして、差圧センサ２３の応答周波数を段階的に低くし、得られる排ガス流量の測定値について調べた。その結果を図３のグラフに示す。なお、図３において、横軸には差圧センサ２３の応答周波数〔Ｈｚ〕、縦軸には排ガス流量の測定値〔Ｌ／ｍｉｎ〕をとっている。   In order to confirm the above, a simulation was performed using a computer. This simulation is based on the exhaust gas flow rate obtained by actually measuring the exhaust gas G having a pulsation frequency of 22 [Hz] using the differential pressure sensor 23 having a response frequency of 2000 [Hz]. The response frequency was lowered stepwise, and the measured value of the exhaust gas flow rate obtained was examined. The result is shown in the graph of FIG. In FIG. 3, the horizontal axis represents the response frequency [Hz] of the differential pressure sensor 23, and the vertical axis represents the measured value [L / min] of the exhaust gas flow rate.

図３から明らかなように、差圧センサ２３の応答周波数が脈動周波数よりも低くなればなるほど排ガス流量の測定値が大きくなる傾向が顕著にあらわれているとともに、差圧センサ２３の応答周波数が脈動周波数と同じ程度であれば、誤差は僅かであり、また、差圧センサ２３の応答周波数を脈動周波数の４〜５倍以上とした場合には、その誤差はほとんど無くなることがわかる。   As apparent from FIG. 3, the measured value of the exhaust gas flow rate tends to increase as the response frequency of the differential pressure sensor 23 becomes lower than the pulsation frequency, and the response frequency of the differential pressure sensor 23 pulsates. If the frequency is the same as the frequency, the error is slight, and if the response frequency of the differential pressure sensor 23 is 4 to 5 times the pulsation frequency, the error is almost eliminated.

従って、排ガス流量計測装置Ｄでは、演算処理装置１７において、差圧センサ２３の差圧信号が示す差圧の瞬時値を、排ガスＧの流量に変換した後、平均化することにより排ガスＧの平均流量を求めるように構成することで、非常に精度良く排ガス流量を導出することができる。   Therefore, in the exhaust gas flow rate measuring device D, the arithmetic processing unit 17 converts the instantaneous value of the differential pressure indicated by the differential pressure signal of the differential pressure sensor 23 into the flow rate of the exhaust gas G, and then averages the averaged exhaust gas G. By configuring so as to obtain the flow rate, the exhaust gas flow rate can be derived with very high accuracy.

また、この実施例の排ガス流量計測装置Ｄでは、全圧検出部１８と差圧センサ２３との間および静圧検出部１９と差圧センサ２３との間に応答差調整機構２６を設けてあるので、上述した位相誤差を非常に小さくするあるいは無くすことができる。   Further, in the exhaust gas flow rate measuring device D of this embodiment, a response difference adjusting mechanism 26 is provided between the total pressure detecting unit 18 and the differential pressure sensor 23 and between the static pressure detecting unit 19 and the differential pressure sensor 23. Therefore, the phase error described above can be made very small or eliminated.

詳しくは、図４に示すように、例えば、全圧検出部１８により検出される全圧（図４（Ａ）参照）と静圧検出部１９により検出される静圧（図４（Ｃ）参照）との間に応答時間の差τがある場合、従来は、図５に示すように、応答時間の差τを調整することなく、全圧（図５（Ａ）参照、図４（Ａ）のものと同じ）と静圧（図５（Ｂ）参照、図４（Ｃ）のものと同じ）との差（図５（Ｃ）参照）を差圧信号として出力していたので、位相誤差が生じることとなっていた。   Specifically, as shown in FIG. 4, for example, the total pressure detected by the total pressure detector 18 (see FIG. 4A) and the static pressure detected by the static pressure detector 19 (see FIG. 4C). ), There is a response time difference τ between the total pressure (see FIG. 5A and FIG. 4A) without adjusting the response time difference τ as shown in FIG. Since the difference (see FIG. 5C) between the static pressure (see FIG. 5B and the same as FIG. 4C) is output as a differential pressure signal, the phase error Was supposed to occur.

しかし、この実施例の排ガス流量計測装置Ｄでは、応答差調整機構２６によって応答時間の差τを調整するのであり、例えば、図４（Ｂ）に示すように、全圧が時間軸方向にτだけ平行移動するように調整し、図６に示すように、調整後の全圧（図６（Ａ）参照、図４（Ｂ）のものと同じ）と静圧（図６（Ｂ）参照、図４（Ｃ）のものと同じ）との差（図６（Ｃ）参照）を差圧信号として出力するので、位相誤差を無くすことができる。   However, in the exhaust gas flow rate measuring device D of this embodiment, the response time difference τ is adjusted by the response difference adjusting mechanism 26. For example, as shown in FIG. 4B, the total pressure is τ in the time axis direction. As shown in FIG. 6, the total pressure after adjustment (see FIG. 6A, the same as that in FIG. 4B) and static pressure (see FIG. 6B), Since the difference (refer to FIG. 6C) with respect to (the same as that in FIG. 4C) is output as a differential pressure signal, the phase error can be eliminated.

さらに、従来は、図５に示すように、差圧信号を用いて排ガス流量を導出する演算の周期Ｔ0 が、脈動の周期よりも長かったので、これによっても正確な排ガス流量の導出が困難であったが、この実施例の排ガス流量計測装置Ｄでは、差圧センサ２３の応答周波数を脈動周波数以上とするとともに、図６に示すように、差圧信号を用いて排ガス流量を導出する演算の周期Ｔ1 が、脈動の周期よりも短くしてあるので、正確な排ガス流量が確実に導出される。なお、周期Ｔ1 を、脈動の周期とほぼ同じ程度としてもよい。 Further, conventionally, as shown in FIG. 5, the calculation period T 0 for deriving the exhaust gas flow rate using the differential pressure signal is longer than the pulsation cycle, which makes it difficult to accurately derive the exhaust gas flow rate. However, in the exhaust gas flow rate measuring device D of this embodiment, the response frequency of the differential pressure sensor 23 is set to be equal to or higher than the pulsation frequency, and the exhaust gas flow rate is derived using the differential pressure signal as shown in FIG. Since the period T 1 is shorter than the period of pulsation, an accurate exhaust gas flow rate is reliably derived. The period T 1 may be substantially the same as the pulsation period.

ここで、脈動時の排ガスＧが流路２において瞬間的に逆流することが知られている。そのため、この実施例の排ガス流量計測装置Ｄでは、差圧センサ２３の差圧信号が示す差圧の平方根と排ガス流量とが比例することに基づいて排ガス流量を演算しているが、排ガスＧが逆流することにより、差圧センサ２３の差圧信号が示す差圧が負となったときには、差圧信号が示す差圧の絶対値の平方根に−１を乗じた値と排ガス流量とが比例することに基づいて排ガス流量を演算するように構成してある。   Here, it is known that the exhaust gas G at the time of pulsation instantaneously flows backward in the flow path 2. Therefore, in the exhaust gas flow rate measuring device D of this embodiment, the exhaust gas flow rate is calculated based on the fact that the square root of the differential pressure indicated by the differential pressure signal of the differential pressure sensor 23 is proportional to the exhaust gas flow rate. When the differential pressure indicated by the differential pressure signal of the differential pressure sensor 23 becomes negative due to the reverse flow, a value obtained by multiplying the square root of the absolute value of the differential pressure indicated by the differential pressure signal by −1 is proportional to the exhaust gas flow rate. Based on this, the exhaust gas flow rate is calculated.

詳しくは、差圧センサ２３の差圧信号が示す差圧が正であるときには、上記（１）式に基づいた演算を行い、負であるときには、標準状態換算の排ガス流量Ｑ（ｔ）〔ｍ3 ／ｍｉｎ〕を、上記（２）式に基づいた演算を行うことによって導出する。 Specifically, when the differential pressure indicated by the differential pressure signal of the differential pressure sensor 23 is positive, the calculation based on the above equation (1) is performed, and when the differential pressure is negative, the exhaust gas flow rate Q (t) [m] in terms of the standard state is calculated. 3 / min] is derived by performing an operation based on the above equation (2).

すなわち、排ガスＧが逆流した場合にも、比例係数α’を予め求めておけば、管内を流れる排ガスの温度、圧力、ピトー管の差圧の測定値から、排ガスの流量を得ることができる。   That is, even when the exhaust gas G flows backward, if the proportionality coefficient α ′ is obtained in advance, the flow rate of the exhaust gas can be obtained from the measured values of the temperature, pressure, and differential pressure of the Pitot tube flowing in the pipe.

なお、この実施例は、種々に変形することができる。例えば、前記希釈ガスＫは、Ｎ2 に限られず、Ｎ2 以外の不活性ガスや精製空気などでもよい。 This embodiment can be variously modified. For example, the diluent gas K is not limited to N 2, or the like inert gas or purified air other than N 2.

また、差圧センサ２３は、自動車１のエンジンがアイドル状態のときの排ガスＧの脈動周波数以上の応答周波数で静圧と全圧との差圧を検出するものに限られず、例えば、エンジンがアイドル状態からアクセル全開状態までの全ての状態における排ガスＧの脈動周波数（例えば、１００〔Ｈｚ〕）以上の応答周波数で静圧と全圧との差圧を検出するように構成してあってもよい。   The differential pressure sensor 23 is not limited to a sensor that detects a differential pressure between static pressure and total pressure at a response frequency equal to or higher than the pulsation frequency of the exhaust gas G when the engine of the automobile 1 is in an idle state. The differential pressure between the static pressure and the total pressure may be detected with a response frequency equal to or higher than the pulsation frequency (for example, 100 [Hz]) of the exhaust gas G in all states from the state to the accelerator fully open state. .

テールパイプアタッチメント１５を設けず、差圧式流量計１６および演算処理装置１７を自動車の排気管１４に直接取り付けてもよい。この場合には、排気管１４のみによって流路２が構成されることとなる。   Instead of providing the tail pipe attachment 15, the differential pressure type flow meter 16 and the arithmetic processing unit 17 may be directly attached to the exhaust pipe 14 of the automobile. In this case, the flow path 2 is constituted only by the exhaust pipe 14.

差圧式流量計１６は、ピトー管式流量計に限られず、例えば、オリフィス式流量計や、ベンチュリ式差圧流量計であってもよい。   The differential pressure type flow meter 16 is not limited to a Pitot tube type flow meter, and may be, for example, an orifice type flow meter or a venturi type differential pressure flow meter.

ピトー管２０は、二重管構造のものに限られず、例えば、全圧検出用ピトー管１８と静圧検出用ピトー管１９とを別々に有するものでもよい。   The Pitot tube 20 is not limited to a double tube structure, and may include, for example, a total pressure detecting Pitot tube 18 and a static pressure detecting Pitot tube 19 separately.

第１連通部２１および第２連通部２２は両方設けるものに限られず、例えば、一方のみを設けるようにしてもよい。また、応答差調整機構２６を、第１連通部２１および第２連通部２２の両方に設けず、いずれか一方のみに設けてもよい。   The first communication part 21 and the second communication part 22 are not limited to those provided, and for example, only one of them may be provided. Further, the response difference adjusting mechanism 26 may be provided only in one of the first communication portion 21 and the second communication portion 22 without being provided in both.

応答差調整機構２６は、絞り弁に限られず、例えば、バッファタンクまたはキャピラリでもよく、また、第１連通部２１を構成する配管の長さおよび／または第２連通部２２を構成する配管の長さを調整することにより応答差調整機構２６の機能を発揮させてもよい。さらに、応答差調整機構２６を設けず、例えば、全圧と静圧とを別々に測定し、各測定値を用いて信号処理によって差圧を導出するようにし、このとき、全圧と静圧との応答時間の差を、信号処理によって調整することにより無くすようにしてもよい。   The response difference adjusting mechanism 26 is not limited to the throttle valve, and may be, for example, a buffer tank or a capillary, and the length of the pipe constituting the first communication portion 21 and / or the length of the pipe constituting the second communication portion 22. The function of the response difference adjusting mechanism 26 may be exhibited by adjusting the height. Further, the response difference adjusting mechanism 26 is not provided, for example, the total pressure and the static pressure are measured separately, and the differential pressure is derived by signal processing using each measured value. At this time, the total pressure and the static pressure are determined. The difference in response time may be eliminated by adjusting by signal processing.

演算処理装置１７を、差圧式流量計１６とともにテールパイプアタッチメント１５に取り付けず、テールパイプアタッチメント１５および差圧式流量計１６から離した位置（例えば、自動車１の座席上）などに配置してもよい。   The arithmetic processing unit 17 may not be attached to the tail pipe attachment 15 together with the differential pressure type flow meter 16 but may be disposed at a position separated from the tail pipe attachment 15 and the differential pressure type flow meter 16 (for example, on the seat of the automobile 1). .

この発明の一実施例に係る排ガス計測システムの構成を概略的に示す説明図である。It is explanatory drawing which shows roughly the structure of the exhaust gas measurement system which concerns on one Example of this invention. 上記実施例における排ガス流量計測装置の構成を概略的に示す説明図である。It is explanatory drawing which shows roughly the structure of the exhaust gas flow measuring device in the said Example. シミュレーションによって得られた差圧センサの応答周波数と排ガス流量の測定値との関係を概略的に示すグラフである。It is a graph which shows roughly the relation between the response frequency of the differential pressure sensor obtained by simulation, and the measured value of exhaust gas flow. （Ａ）は、全圧検出部により検出される全圧の経時変化を概略的に示すグラフ、（Ｂ）は、（Ａ）に示すグラフを平行移動させて得られたグラフ、（Ｃ）は、静圧検出部により検出される静圧の経時変化を概略的に示すグラフである。(A) is a graph schematically showing the change over time of the total pressure detected by the total pressure detector, (B) is a graph obtained by translating the graph shown in (A), (C) is 4 is a graph schematically showing a change with time in static pressure detected by a static pressure detection unit. （Ａ）は、図４（Ａ）に示すグラフ、（Ｂ）は、図４（Ｃ）に示すグラフ、（Ｃ）は、（Ａ）と（Ｂ）の差をとって示すグラフである。(A) is a graph shown in FIG. 4 (A), (B) is a graph shown in FIG. 4 (C), and (C) is a graph showing the difference between (A) and (B). （Ａ）は、図４（Ｂ）に示すグラフ、（Ｂ）は、図４（Ｃ）に示すグラフ、（Ｃ）は、（Ａ）と（Ｂ）の差をとって示すグラフである。(A) is a graph shown in FIG. 4 (B), (B) is a graph shown in FIG. 4 (C), and (C) is a graph showing the difference between (A) and (B). ピトー管式流量計における差圧と流量との関係を概略的に示すグラフである。It is a graph which shows roughly the relationship between the differential pressure | voltage and flow volume in a Pitot tube type flow meter.

符号の説明Explanation of symbols

２ 流路
１８ 全圧検出部
１９ 静圧検出部
２３ 差圧センサ
Ｄ 排ガス流量計測装置
Ｇ 排ガス 2 Flow path 18 Total pressure detector 19 Static pressure detector 23 Differential pressure sensor D Exhaust gas flow measuring device G Exhaust gas

Claims (10)

エンジンから排出された排ガスが流れる流路にそれぞれ設けられる全圧検出部および静圧検出部と、全圧検出部および静圧検出部が接続される差圧センサと、演算処理装置とを備え、前記差圧センサが、排ガスの脈動周波数以上の応答周波数で静圧と全圧との差圧を検出して差圧信号を前記演算処理装置に出力する高速応答型差圧センサであり、該演算処理装置は前記差圧信号が示す差圧の瞬時値を用い、排ガス流量を導出する演算の周波数が前記脈動周波数以上になるように排ガス流量を算出するように構成してあることを特徴とする排ガス流量計測装置。 A total pressure detection unit and a static pressure detection unit respectively provided in a flow path through which exhaust gas discharged from the engine flows, a differential pressure sensor to which the total pressure detection unit and the static pressure detection unit are connected, and an arithmetic processing unit, The differential pressure sensor is a high-speed differential pressure sensor that detects a differential pressure between a static pressure and a total pressure at a response frequency equal to or higher than a pulsation frequency of exhaust gas and outputs a differential pressure signal to the arithmetic processing unit. processor uses an instantaneous value of the differential pressure indicated by the differential pressure signal, wherein the frequency of operation for deriving the exhaust gas flow is arranged to calculate the exhaust gas flow rate to be equal to or greater than the said pulse frequency Exhaust gas flow measuring device. エンジンから排出された排ガスが流れる流路にそれぞれ設けられる全圧検出部および静圧検出部と、全圧検出部および静圧検出部が接続される差圧センサと、演算処理装置とを備え、前記差圧センサが、エンジンがアイドル状態のときの排ガスの脈動周波数以上の応答周波数で静圧と全圧との差圧を検出して差圧信号を前記演算処理装置に出力する高速応答型差圧センサであり、該演算処理装置は前記差圧信号が示す差圧の瞬時値を用い、排ガス流量を導出する演算の周波数が前記脈動周波数以上になるように排ガス流量を算出するように構成してあることを特徴とする排ガス流量計測装置。 A total pressure detection unit and a static pressure detection unit respectively provided in a flow path through which exhaust gas discharged from the engine flows, a differential pressure sensor to which the total pressure detection unit and the static pressure detection unit are connected, and an arithmetic processing unit, The differential pressure sensor detects a differential pressure between a static pressure and a total pressure at a response frequency equal to or higher than a pulsation frequency of exhaust gas when the engine is in an idle state, and outputs a differential pressure signal to the arithmetic processing unit. a pressure sensor, the processor uses an instantaneous value of the differential pressure indicated by the differential pressure signal, configured to calculate the exhaust gas flow rate so that the frequency of operation for deriving the exhaust gas flow rate becomes equal to or higher than the pulse frequency Exhaust gas flow rate measuring device characterized by that. 差圧センサが、半導体差圧センサである請求項１または２に記載の排ガス流量計測装置。   The exhaust gas flow rate measuring device according to claim 1 or 2, wherein the differential pressure sensor is a semiconductor differential pressure sensor. 全圧検出部と差圧センサとの間および／または静圧検出部と差圧センサとの間に、応答差調整機構が設けられている請求項１〜３のいずれかに記載の排ガス流量計測装置。   The exhaust gas flow rate measurement according to any one of claims 1 to 3, wherein a response difference adjusting mechanism is provided between the total pressure detection unit and the differential pressure sensor and / or between the static pressure detection unit and the differential pressure sensor. apparatus. 応答差調整機構が、バッファタンクまたはキャピラリまたは絞り弁である請求項４に記載の排ガス流量計測装置。   The exhaust gas flow rate measuring device according to claim 4, wherein the response difference adjusting mechanism is a buffer tank, a capillary or a throttle valve. 全圧検出部と差圧センサとの間および／または静圧検出部と差圧センサとの間に連通部が設けられており、この連通部が、２０ｍ以下の長さを有し、１．０〜５０ｍｍの内径を有する配管により構成されている請求項１〜５のいずれかに記載の排ガス流量計測装置。   A communication part is provided between the total pressure detection part and the differential pressure sensor and / or between the static pressure detection part and the differential pressure sensor, and the communication part has a length of 20 m or less. The exhaust gas flow rate measuring device according to any one of claims 1 to 5, wherein the exhaust gas flow rate measuring device is constituted by a pipe having an inner diameter of 0 to 50 mm. 差圧信号が示す差圧の平方根と排ガス流量とが比例することに基づいて排ガス流量を演算し、差圧信号が示す差圧が負であるときには、差圧信号が示す差圧の絶対値の平方根に−１を乗じた値と排ガス流量とが比例することに基づいて排ガス流量を演算するように構成された請求項１〜６のいずれかに記載の排ガス流量計測装置。   The exhaust gas flow rate is calculated based on the fact that the square root of the differential pressure indicated by the differential pressure signal is proportional to the exhaust gas flow rate, and when the differential pressure indicated by the differential pressure signal is negative, the absolute value of the differential pressure indicated by the differential pressure signal is calculated. The exhaust gas flow rate measuring device according to any one of claims 1 to 6, wherein the exhaust gas flow rate is calculated based on a proportionality between a value obtained by multiplying a square root by -1 and an exhaust gas flow rate. 差圧信号が示す差圧を、流量に変換した後、平均化することにより排ガスの平均流量を求めるように構成された請求項１〜７のいずれかに記載の排ガス流量計測装置。   The exhaust gas flow rate measuring device according to any one of claims 1 to 7, configured to obtain an average flow rate of exhaust gas by converting the differential pressure indicated by the differential pressure signal into a flow rate and then averaging the converted flow rate. 車載タイプとした請求項１〜８のいずれかに記載の排ガス流量計測装置。   The exhaust gas flow rate measuring device according to any one of claims 1 to 8, wherein the exhaust gas flow rate measuring device is a vehicle-mounted type. 請求項１〜９のいずれかに記載の排ガス流量計測装置を備えた排ガス計測システム。   An exhaust gas measurement system comprising the exhaust gas flow rate measuring device according to any one of claims 1 to 9.
JP2003294239A 2003-08-18 2003-08-18 Exhaust gas flow measuring device and exhaust gas measuring system using the same Expired - Lifetime JP4447266B2 (en)

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JP2003294239A JP4447266B2 (en) 2003-08-18 2003-08-18 Exhaust gas flow measuring device and exhaust gas measuring system using the same
DE602004004709T DE602004004709T2 (en) 2003-08-18 2004-08-16 Method and device for measuring the exhaust gas flow
EP07002436A EP1793210A3 (en) 2003-08-18 2004-08-16 Emission flow rate measuring method and apparatus
EP17157248.0A EP3190393A1 (en) 2003-08-18 2004-08-16 Emission flow rate measuring method and apparatus
DE07002436.9T DE07002436T1 (en) 2003-08-18 2004-08-16 Method and apparatus for measuring emission throughput
EP04019438A EP1508788B1 (en) 2003-08-18 2004-08-16 Emission flow rate measuring method and apparatus
DE17157248.0T DE17157248T1 (en) 2003-08-18 2004-08-16 EMISSION RUNNING MEASUREMENT METHOD AND DEVICE
US10/919,925 US7110878B2 (en) 2003-08-18 2004-08-17 Method and apparatus for measuring exhaust gas flow rate and it's application system for analyzing the exhaust gases from an engine

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