WO2022080113A1 - Differential pressure-type flow meter, exhaust gas analysis device, flow rate measurement method, exhaust gas analysis method, and program for differential pressure-type flow meter - Google Patents

Differential pressure-type flow meter, exhaust gas analysis device, flow rate measurement method, exhaust gas analysis method, and program for differential pressure-type flow meter Download PDF

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WO2022080113A1
WO2022080113A1 PCT/JP2021/034977 JP2021034977W WO2022080113A1 WO 2022080113 A1 WO2022080113 A1 WO 2022080113A1 JP 2021034977 W JP2021034977 W JP 2021034977W WO 2022080113 A1 WO2022080113 A1 WO 2022080113A1
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differential pressure
flow rate
exhaust gas
pressure
flow path
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PCT/JP2021/034977
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French (fr)
Japanese (ja)
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真 永岡
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株式会社堀場製作所
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Priority to JP2022557324A priority Critical patent/JPWO2022080113A1/ja
Publication of WO2022080113A1 publication Critical patent/WO2022080113A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
    • G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
    • G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
    • G01F1/40—Details of construction of the flow constriction devices
    • G01F1/46—Pitot tubes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/72—Devices for measuring pulsing fluid flows

Definitions

  • the present invention relates to a differential pressure type flow meter, an exhaust gas analyzer, a flow rate measuring method, an exhaust gas analysis method, and a program for a differential pressure type flow meter.
  • various exhaust gas analyzers are mounted on the vehicle, and the exhaust gas discharged from the tail pipe is sampled to analyze each component contained in the exhaust gas.
  • a differential pressure type flow meter such as a Pitot tube type flow meter for measuring the flow rate of exhaust gas is installed in the tail pipe, and the exhaust gas flow rate obtained by the flow meter and the exhaust gas analyzer are obtained.
  • the exhaust mass of each component is calculated from the concentration of each component.
  • a differential pressure type flow meter such as a Pitot tube type flow meter calculates a flow rate using a relational expression based on a differential pressure assuming a steady flow, but the exhaust gas from the vehicle is an unsteady flow accompanied by pulsation. Therefore, it is difficult to accurately measure the exhaust gas flow rate.
  • a configuration in which a buffer tank is provided to reduce unsteady flow accompanied by pulsation is conceivable, but the size of the device becomes large.
  • the pulsation conditions are known, it is possible to correct the exhaust gas flow rate, but this is also not realistic.
  • the present invention has been made to solve the above-mentioned problems, and its main task is to measure the flow rate of unsteady flow accompanied by pulsation with high accuracy.
  • the differential pressure type flow meter detects the differential pressure of the fluid flowing through the symmetrical flow path portion symmetrical to the upstream side and the downstream side from the predetermined reference position, and calculates the flow rate of the fluid from the differential pressure.
  • a pressure detection unit and a flow rate calculation unit that calculates a flow rate from the first differential pressure and the second differential pressure using a predetermined calculation formula are provided, and the predetermined calculation formula is the first differential pressure.
  • the first calculation formula that obtains the flow rate from the above and includes the time change term of the flow rate and the second calculation formula that obtains the flow rate from the second differential pressure and includes the time change term of the flow rate. It is characterized by eliminating the time-varying term of the flow rate, which is a common term.
  • the first differential pressure and the second differential pressure in the flow path are detected, and the flow rate is obtained from the first differential pressure, and the first calculation including the time change term of the flow rate.
  • the flow rate is calculated by the calculation formula that eliminates the time change term of the flow rate, which is a common term, using the formula and the second calculation formula that obtains the flow rate from the second differential pressure and includes the time change term of the flow rate. Therefore, it is possible to measure the flow rate of unsteady flow accompanied by pulsation with high accuracy. Further, since the flow rate is obtained by detecting the first differential pressure and the second differential pressure in the symmetrical flow path portion, the flow rate when the fluid flows in the opposite direction (when the fluid flows backward) is obtained with high accuracy. be able to.
  • the symmetric flow path is described.
  • the first to third pressure guiding tubes that communicate with each other to receive the pressure of the fluid and are arranged in order from the upstream side, and the first differential pressure detecting unit is connected to the first to third pressure guiding tubes. It is desirable that the combination of the pressure guiding tubes and the combination of the first to third pressure guiding tubes to which the second differential pressure detecting unit is connected are different from each other.
  • the distance between the first pressure guiding tube and the second pressure guiding tube is the same as the distance between the second pressure guiding tube and the third pressure guiding tube.
  • the first pressure guiding tube is open toward the upstream side in the symmetrical flow path portion, and the third pressure guiding tube is open toward the downstream side in the symmetrical flow path portion. It is desirable that the pressure guiding tube 2 is open to the tube wall forming the symmetrical flow path portion.
  • the first pressure guiding tube receives the total pressure of the fluid
  • the second pressure guiding tube and the third pressure guiding tube are static of the fluid. You will be under pressure.
  • the third pressure guiding tube receives the total pressure of the fluid
  • the first pressure guiding tube and the second pressure guiding tube receive the static pressure of the fluid. become. This makes it possible to measure the flow rate of unsteady flow accompanied by pulsation and backflow with high accuracy in the Pitot tube type flow meter.
  • the first calculation formula is the following formula (1)
  • the second calculation formula is the following formula (2).
  • C 1 is a coefficient related to the distance of the pressure guiding tube for measuring the first differential pressure and the change in the shape of the flow path of the portion
  • ⁇ is the density of the fluid
  • ⁇ P 1 is the density of the fluid
  • K 1 is a coefficient obtained from the relationship between the differential pressure and the flow rate in the flow path portion where the first differential pressure is detected.
  • C 2 is a coefficient related to the distance of the pressure guiding tube for measuring the second differential pressure and the change in the shape of the flow path of the portion
  • ⁇ is the density of the fluid
  • ⁇ P 2 is the density of the fluid
  • K 2 is a coefficient obtained from the relationship between the differential pressure and the flow rate in the flow path portion where the second differential pressure is detected.
  • the calculation formula in which the time change term is eliminated by using the first calculation formula and the second calculation formula is the following formula (3), and the flow rate calculation unit uses the following formula (3). It is conceivable to calculate the flow rate from the first differential pressure and the second differential pressure.
  • ⁇ is C 2 / C 1 .
  • the flow rate calculation method detects the differential pressure of the fluid flowing through the symmetrical flow path portion symmetrical to the upstream side and the downstream side from the predetermined reference position, and calculates the flow rate of the fluid from the differential pressure.
  • the first differential pressure in the symmetrical flow path portion is detected
  • the second differential pressure in the symmetrical flow path portion is detected
  • the first differential pressure and the second differential pressure are detected.
  • the flow rate is calculated using a predetermined calculation formula from the above, and as the predetermined calculation formula, the flow rate is obtained from the first differential pressure, and the first calculation formula including the time change term of the flow rate.
  • the flow rate is obtained from the second differential pressure, and the one in which the time change term of the flow rate, which is a common term, is eliminated by using the second calculation formula including the time change term of the flow rate is used. It is a feature.
  • an exhaust gas analysis method for measuring the flow rate of exhaust gas using the differential pressure type flow meter according to the present invention is also one aspect of the present invention.
  • the program used in the differential pressure flow meter is the first to detect the first differential pressure of the fluid flowing through the symmetrical flow path portion symmetrical to the upstream side and the downstream side from the predetermined reference position.
  • a differential pressure type flow meter having a differential pressure detecting unit and a second differential pressure detecting unit for detecting a second differential pressure of the fluid flowing through the symmetrical flow path portion, and calculating the flow rate of the fluid from the differential pressure.
  • the program to be used is to equip the computer with a function as a flow rate calculation unit for calculating a flow rate from the first differential pressure and the second differential pressure using a predetermined calculation formula, and the predetermined one.
  • the calculation formulas are the first calculation formula that obtains the flow rate from the first differential pressure and includes the time change term of the flow rate, and the calculation formula that obtains the flow rate from the second differential pressure and the time of the flow rate. It is characterized in that the time change term of the flow rate, which is a common term, is eliminated by using the second arithmetic expression including the change term.
  • the exhaust gas analyzer 100 of the present embodiment is mounted on a vehicle V, for example, and is a vehicle-mounted type that analyzes the exhaust gas discharged from the internal combustion engine E of the vehicle when the vehicle V travels on the road in real time while traveling on the road. belongs to.
  • the exhaust gas analyzer 100 is a direct sampling method that measures the concentration of the collected exhaust gas as it is without diluting it. It should be noted that the exhaust gas emitted from the internal combustion engine of the vehicle simulated on the chassis dynamometer may be analyzed in real time during the simulated traveling.
  • the exhaust gas analyzer 100 is attached to the opening EH1 of the exhaust pipe EH connected to the internal combustion engine E, and measures the flow rate of the exhaust gas discharged from the exhaust pipe EH. It includes a differential pressure type flow meter 2 and a gas analyzer 3 for measuring the concentration of the component to be measured contained in the exhaust gas discharged from the exhaust pipe EH.
  • the differential pressure type flow meter 2 detects the differential pressure of the exhaust gas flowing through the flow path and calculates the flow rate of the exhaust gas from the differential pressure.
  • a first differential pressure detecting unit 22 and a second differential pressure detecting unit 23 for detecting the differential pressure of the exhaust gas flowing through the mounting pipe 21 are provided. The details of the differential pressure type flow meter 2 will be described later.
  • the gas analyzer 3 continuously measures the concentration of the measurement target component (for example, CO, CO 2 , NO X , THC, etc.) contained in the exhaust gas.
  • an NDIR detector using a non-dispersive infrared absorption method can be used to measure the NO X concentration.
  • NDIR method non-dispersive infrared absorption method
  • a CLD detector using a chemical emission analysis method (CLD) can be used
  • FID detection using a hydrogen flame ionization analysis method (FID) can be used.
  • a vessel can be used.
  • the gas analyzer 3 may have any of these detectors, or may have a plurality of types of detectors among the above.
  • the gas analyzer 3 can be a detector using various analytical methods depending on the component to be measured.
  • an introduction pipe 6 for introducing the sampled exhaust gas is connected to the gas analyzer 3.
  • One end of the introduction pipe 6 is connected to the gas analyzer 3, and the other end of the introduction pipe 6 is provided with an exhaust gas sampling unit 7 for sampling exhaust gas.
  • the exhaust gas sampling unit 7 is provided in the mounting pipe 21 of the above-mentioned differential pressure type flow meter.
  • the exhaust gas sampling unit 7 is composed of a sampling pipe that collects a part of the exhaust gas flowing through the mounting pipe 21.
  • the exhaust gas sampling unit 7 is provided in the mounting pipe 21 on the downstream side of the first and second differential pressure detecting units 22 and 23, and is provided on the downstream side of the first and second differential pressure detecting units 22 and 23.
  • the differential pressure detection is not affected by pressure fluctuations.
  • the concentration signal of each component obtained by the gas analyzer 3 is sent to the upper arithmetic unit 8, and together with the flow rate signal output from the flow rate calculation unit 24 of the differential pressure type flow meter 2, the emission mass of each component is measured. Used for calculation.
  • differential pressure type flow meter 2 detects the differential pressure of the exhaust gas flowing through the flow path and calculates the flow rate of the exhaust gas from the differential pressure.
  • the exhaust pipe A mounting pipe 21 externally attached to the opening EH1 of the EH, and a first differential pressure detecting unit 22 and a second differential pressure detecting unit 23 for detecting the differential pressure of the exhaust gas flowing through the mounting pipe 21 are provided. ing.
  • the mounting pipe 21 has a straight pipe shape that is mounted so as to cover the outer peripheral surface of the opening EH1 of the exhaust pipe EH.
  • it is a circular tube having a circular cross section. Then, one end opening of the mounting pipe 21 is attached to the opening EH1 of the exhaust pipe EH, and the other end opening is open, and the exhaust gas is discharged to the outside from the other end opening.
  • the first differential pressure detecting unit 22 detects the first differential pressure ⁇ P 1 , which is the differential pressure between the total pressure and the static pressure of the exhaust gas in the flow path R in the mounting pipe 21. Further, the second differential pressure detecting unit 23 detects the second differential pressure ⁇ P 2 , which is the differential pressure between the total pressure and the static pressure of the exhaust gas in the flow path R in the mounting pipe 21. Further, the first differential pressure ⁇ P 1 detected by the first differential pressure detecting unit 22 and the second differential pressure ⁇ P 2 detected by the second differential pressure detecting unit 23 are the flows of the mounting pipe 21. The differential pressure between different positions on the road.
  • the flow path R of the mounting pipe 21 has a symmetrical flow path portion R1 that is symmetrical to the upstream side and the downstream side from a predetermined reference position.
  • the reference position is the axial center position of the mounting pipe 21, and the entire flow path R of the mounting pipe 21 constitutes the symmetrical flow path portion R1. That is, the first differential pressure detecting unit 22 and the second differential pressure detecting unit 23 detect the differential pressure between different positions in the symmetrical flow path portion R1.
  • the first differential pressure detecting unit 22 and the second differential pressure detecting unit 23 are connected to the first to third pressure guiding tubes 25 to 27 provided in the symmetrical flow path portion R1.
  • the first differential pressure ⁇ P 1 and the second differential pressure ⁇ P 2 in the symmetrical flow path portion R1 are detected.
  • the first to third pressure guiding tubes 25 to 27 communicate with the symmetrical flow path portion R1 to receive the pressure of the fluid and are arranged in this order from the upstream side.
  • the first pressure guiding pipe 25 is opened toward the upstream side (one end opening side) in the flow path R (symmetrical flow path portion R1) of the mounting pipe 21.
  • the first pressure guiding tube 25 detects the total pressure of the exhaust gas when the exhaust gas flows in the forward direction, and detects the static pressure of the exhaust gas when the exhaust gas flows in the opposite direction. Become.
  • the second pressure guiding pipe 26 is open to the pipe wall (tube wall of the mounting pipe 21) forming the symmetrical flow path portion R1 toward the inside of the flow path (center axis side of the mounting pipe 21).
  • the second pressure guiding tube 26 detects the static pressure of the exhaust gas regardless of the direction in which the exhaust gas flows (forward and reverse directions).
  • the third pressure guiding pipe 27 is opened toward the downstream side (the other end opening side) in the flow path R (symmetrical flow path portion R1) of the mounting pipe 21.
  • the third pressure guiding tube 27 detects the static pressure of the exhaust gas when the exhaust gas flows in the forward direction, and detects the total pressure of the exhaust gas when the exhaust gas flows in the reverse direction. Become.
  • the distance L1 between the first pressure guiding tube 25 and the second pressure guiding tube 26 and the distance L2 between the second pressure guiding tube 26 and the third pressure guiding tube 27 are arranged so as to be the same.
  • the distance between the pressure guiding tubes 25 to 27 is the distance between the pressure measuring openings of the pressure guiding tubes 25 to 27.
  • the positional relationship of the first to third pressure guiding tubes 25 to 27 in the circumferential direction does not have to be on a straight line, and may be different positions in the circumferential direction.
  • the first to third pressure guiding tubes to which the first differential pressure detecting unit 22 is connected are connected.
  • the combination of 25 to 27 and the combination of the first to third pressure guiding tubes 25 to 27 to which the second differential pressure detecting unit 23 is connected are configured to be different from each other.
  • the first differential pressure detecting unit 22 is connected to the first pressure guiding tube 25 and the third pressure guiding tube 27, and the second differential pressure detecting unit 23 is the first pressure guiding tube 25. And is connected to the second pressure guiding tube 26.
  • the flow rate calculation unit 24 of the differential pressure type flow meter 2 has a second difference obtained by the first differential pressure ⁇ P 1 obtained by the first differential pressure detecting unit 22 and the second differential pressure detecting unit 23. From the pressure ⁇ P 2 , the volumetric flow rate Q of the exhaust gas is calculated using a predetermined calculation formula.
  • the predetermined calculation formula is for obtaining the flow rate from the first differential pressure ⁇ P 1 , and is derived from the first calculation formula including the time change term dQ / dt of the volume flow rate Q and the second differential pressure ⁇ P 2 .
  • the time change term dQ / dt of the volume flow rate Q which is a common term, is eliminated by using the second arithmetic expression that obtains the volume flow rate Q and includes the time change term dQ / dt of the volume flow rate Q. ..
  • the first arithmetic expression is represented by the following expression (1).
  • C 1 is a coefficient indicating a change in the flow path cross-sectional area of the flow path portion for detecting the first differential pressure ⁇ P 1
  • ⁇ is the fluid density
  • K 1 is the loss coefficient (for example, a coefficient of loss due to shear in a fluid, turbulent energy dissipation, etc.) obtained from the relationship between the differential pressure and the flow rate in the flow path portion where the first differential pressure ⁇ P 1 is detected. The loss coefficient is set based on the result of the steady flow experiment.
  • the second arithmetic expression is expressed by the following expression (2).
  • C 2 is a coefficient indicating a change in the flow path cross-sectional area of the flow path portion for detecting the second differential pressure ⁇ P 2
  • ⁇ is the fluid density
  • K 2 is the loss coefficient (for example, shear in the fluid, turbulent energy dissipation, etc.) that can be experimentally obtained from the relationship between the differential pressure and the flow rate by a steady flow experiment in the flow path portion where the second differential pressure ⁇ P 2 is detected. Loss coefficient). The loss coefficient is set based on the result of the steady flow experiment.
  • the flow rate calculation unit 24 uses the following equation (3), which is a predetermined arithmetic equation in which the time change term dQ / dt is eliminated from the above equations (1) and (2), and the first difference is obtained.
  • the volume flow rate Q is calculated from the pressure ⁇ P 1 and the second differential pressure ⁇ P 2 .
  • ⁇ is C 2 / C 1 .
  • FIG. 3 shows the experimental results of the flow rate error between the conventional differential pressure type flow meter and the differential pressure type flow meter of the present embodiment.
  • the flow rate calculation method of the conventional differential pressure type flow meter is described above.
  • the average error of the differential pressure type flow meter of the present embodiment is smaller than the average error of the conventional differential pressure type flow meter.
  • the first differential pressure ⁇ P 1 and the second differential pressure ⁇ P 2 in the flow path R are detected, and the volume flow rate is increased from the first differential pressure ⁇ P 1 .
  • the first calculation formula including the time change term dQ / dt of the volume flow rate Q, which obtains Q, and the time change term dQ of the volume flow rate Q, which obtains the volume flow rate Q from the second differential pressure ⁇ P2.
  • volume flow rate Q is calculated by the calculation formula in which the time change term dQ / dt of the volume flow rate Q, which is a common term, is eliminated by using the second calculation formula including / dt, the unsteady flow accompanied by pulsation or the like is calculated.
  • the flow rate Q can be measured with high accuracy.
  • first differential pressure detecting unit 22 and the second differential pressure detecting unit 23 detect the differential pressures at different positions in the symmetrical flow path portion R1, when the fluid flows in the opposite direction in the flow path R ( The volumetric flow rate Q (when the fluid flows backward) can be obtained with high accuracy.
  • the distance L1 between the first pressure guiding tube 25 and the second pressure guiding tube 26 and the distance L2 between the second pressure guiding tube 26 and the third pressure guiding tube 27 are the same, and the first to third pressure guiding tubes are the same. Since the arrangement of 25 to 27 has symmetry, the flow rate can be measured with the same measurement accuracy in both the case where the fluid flows in the forward direction and the case where the fluid flows in the reverse direction in the flow path R.
  • the first pressure guiding tube 25 is open toward the upstream side in the symmetric flow path portion R1, and the third pressure guiding tube 27 is open toward the downstream side in the symmetric flow path portion R1. Since the pressure tube 26 is open to the tube wall forming the symmetrical flow path portion R1, when the fluid flows in the forward direction in the flow path R, the first pressure guiding tube 25 receives the total pressure of the fluid. , The second pressure guiding tube 26 and the third pressure guiding tube 27 receive the static pressure of the fluid. Further, when the fluid flows in the reverse direction in the flow path, the third pressure guiding tube 27 receives the total pressure of the fluid, and the first pressure guiding tube 25 and the second pressure guiding tube 26 receive the static pressure of the fluid. Will receive. As a result, the volumetric flow rate Q of the unsteady flow accompanied by pulsation and backflow can be measured with high accuracy in the Pitot tube type flow meter.
  • the combination of the first to third pressure guiding tubes 25 to 27 to which the differential pressure detecting units 22 and 23 are connected is not limited to the above embodiment, and may be other combinations.
  • the number of pressure guiding tubes is not limited to three, and the first differential pressure detecting unit 22 may be provided with two dedicated pressure guiding tubes, and the second differential pressure detecting unit 23 may be provided with two dedicated pressure guiding tubes.
  • the entire flow path of the mounting pipe constitutes the symmetrical flow path portion, but a part of the flow path of the mounting pipe may form the symmetrical flow path portion.
  • the distance L1 between the first pressure guiding tube 25 and the second pressure guiding tube 26 and the distance L2 between the second pressure guiding tube 26 and the third pressure guiding tube 27 are not the same, and the first to third pressure guiding tubes 26 are not the same.
  • the pressure guiding tubes 25 to 27 may be arranged asymmetrically. In this case, the degree of freedom in arranging the pressure guiding tubes 25 to 27 can be increased. For example, under the condition that the value of ⁇ P1- ⁇ P2 / ⁇ in the above-mentioned equation (3) becomes zero or infinitely small, it is possible to improve the measurement accuracy by reexamining the arrangement of the respective conductor tubes 25 to 27. Become.
  • the configuration having the two differential pressure detection units 22 and 23 has been described, but the configuration may have three or more differential pressure detection units.
  • the first pressure guiding tube 25 and the third pressure guiding tube 27 are arranged independently of each other, but inside one pressure guiding tube, there is a pressure guiding flow path that functions as the first pressure guiding tube 25.
  • a pressure guiding channel that functions as a third conductor tube 27 may be formed.
  • differential pressure type flow meter is applied to the exhaust gas analyzer
  • the differential pressure type flow meter may be applied to other analyzers, or the differential pressure type flow meter may be used alone. good.
  • the flow of a fluid accompanied by an unsteady flow such as pulsation can be measured with high accuracy.

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  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
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Abstract

The present invention measures, with high accuracy, the flow rate of a non-steady flow associated with pulsation, and is a differential pressure-type flow meter 2 that detects the differential pressure of a fluid flowing through a symmetrical flow path part and calculates the flow rate Q of the fluid from the differential pressure, said symmetrical flow path part being symmetrical to the upstream side and the downstream side from a prescribed reference location, said pressure-type flow meter 2 comprising: a first differential pressure detection part 22 that detects a first differential pressure P1 in the symmetrical flow path part R1; a second differential pressure detection part 23 that detects a second differential pressure P2 in the symmetrical flow path part R1; and a flow rate calculation part 24 that uses a prescribed arithmetic expression to calculate the flow rate Q from the first differential pressure P1 and the second differential pressure P2, wherein the prescribed arithmetic expression results from using a first arithmetic expression that calculates the flow rate from the first differential pressure P1 and includes a time variation term dQ/dt for the flow rate Q, and a second arithmetic expression that calculates the flow rate Q from the second differential pressure P2 and includes the time variation term dQ/dt for the flow rate Q, and removing the shared term that is the time variation term dQ/dt for the flow rate Q.

Description

差圧式流量計、排ガス分析装置、流量測定方法、排ガス分析方法、及び、差圧式流量計用のプログラムProgram for differential pressure type flow meter, exhaust gas analyzer, flow rate measurement method, exhaust gas analysis method, and differential pressure type flow meter
　本発明は、差圧式流量計、排ガス分析装置、流量測定方法、排ガス分析方法、及び、差圧式流量計用のプログラムに関するものである。 The present invention relates to a differential pressure type flow meter, an exhaust gas analyzer, a flow rate measuring method, an exhaust gas analysis method, and a program for a differential pressure type flow meter.
　従来、例えば車両の路上走行試験では、車両に各種の排ガス分析計を搭載し、テールパイプから排出される排ガスをサンプリングして当該排ガスに含まれる各成分を分析している。また、テールパイプには、排ガスの流量を測定するための例えばピトー管式流量計などの差圧式流量計が設置され、当該流量計により得られた排ガス流量と、前記排ガス分析計により得られた各成分の濃度とから、各成分の排出質量を算出している。 Conventionally, for example, in a vehicle road driving test, various exhaust gas analyzers are mounted on the vehicle, and the exhaust gas discharged from the tail pipe is sampled to analyze each component contained in the exhaust gas. Further, a differential pressure type flow meter such as a Pitot tube type flow meter for measuring the flow rate of exhaust gas is installed in the tail pipe, and the exhaust gas flow rate obtained by the flow meter and the exhaust gas analyzer are obtained. The exhaust mass of each component is calculated from the concentration of each component.
　ところで、例えばピトー管式流量計などの差圧式流量計は、定常流を仮定した差圧に基づく関係式を用いて流量を算出するものであるところ、車両からの排ガスは脈動を伴う非定常流であり、排ガス流量を精度良く測定することが難しい。また、脈動を伴う非定常流を低減すべくバッファタンクを設ける構成も考えられるが、装置が大型化してしまう。さらに、脈動条件が既知であれば、排ガス流量を補正することも考えられるがこれも現実的ではない。 By the way, for example, a differential pressure type flow meter such as a Pitot tube type flow meter calculates a flow rate using a relational expression based on a differential pressure assuming a steady flow, but the exhaust gas from the vehicle is an unsteady flow accompanied by pulsation. Therefore, it is difficult to accurately measure the exhaust gas flow rate. In addition, a configuration in which a buffer tank is provided to reduce unsteady flow accompanied by pulsation is conceivable, but the size of the device becomes large. Furthermore, if the pulsation conditions are known, it is possible to correct the exhaust gas flow rate, but this is also not realistic.
　ここで、特許文献１に示すように、流れの非定常性を考慮して、管内の流れを分流路に分流し、それぞれの分流路内の流れの加速度が互いに等しくなる点で、分流路間の静圧差を検出し、この静圧差から流量を測定する流量計が考えられている。 Here, as shown in Patent Document 1, in consideration of the unsteadiness of the flow, the flow in the pipe is divided into the branch channels, and the accelerations of the flows in the respective branch channels are equal to each other. A flow meter that detects the static pressure difference and measures the flow rate from this static pressure difference has been considered.
　しかしながら、特許文献１の流量計では、流量が分流路の面積比で分配されるとしているが、実際には、面積比の要件を満たしても、分流路の入口部や出口部及び流量形状によって各分流路の圧力損失が異なると、必ずしも面積比では分配されない。そうすると、脈動などを伴う非定常流の流量を高精度に測定することができない。 However, although the flow meter of Patent Document 1 states that the flow rate is distributed by the area ratio of the branch flow path, in reality, even if the requirement of the area ratio is satisfied, the flow rate depends on the inlet and outlet portions of the branch channel and the flow rate shape. If the pressure loss of each branch channel is different, it is not always distributed by the area ratio. Then, the flow rate of the unsteady flow accompanied by pulsation or the like cannot be measured with high accuracy.
特開平７－４３１８３号公報Japanese Unexamined Patent Publication No. 7-43183
　そこで、本発明は上記の問題点を解決すべくなされたものであり、脈動などを伴う非定常流の流量を高精度に測定することをその主たる課題とするものである。 Therefore, the present invention has been made to solve the above-mentioned problems, and its main task is to measure the flow rate of unsteady flow accompanied by pulsation with high accuracy.
　すなわち、本発明に係る差圧式流量計は、所定の基準位置から上流側及び下流側に対称である対称流路部を流れる流体の差圧を検出し、その差圧から前記流体の流量を算出する差圧式流量計であって、前記対称流路部における第１の差圧を検出する第１の差圧検出部と、前記対称流路部における第２の差圧を検出する第２の差圧検出部と、前記第１の差圧及び前記第２の差圧から所定の演算式を用いて流量を算出する流量算出部とを備え、前記所定の演算式は、前記第１の差圧から流量を求めるものであって前記流量の時間変化項を含む第１演算式と、前記第２の差圧から流量を求めるものであって前記流量の時間変化項を含む第２演算式とを用いて、共通項である前記流量の時間変化項を消去したものであることを特徴とする。 That is, the differential pressure type flow meter according to the present invention detects the differential pressure of the fluid flowing through the symmetrical flow path portion symmetrical to the upstream side and the downstream side from the predetermined reference position, and calculates the flow rate of the fluid from the differential pressure. A second difference between a first differential pressure detecting unit that detects a first differential pressure in the symmetrical flow path portion and a second differential pressure detecting the second differential pressure in the symmetrical flow path portion. A pressure detection unit and a flow rate calculation unit that calculates a flow rate from the first differential pressure and the second differential pressure using a predetermined calculation formula are provided, and the predetermined calculation formula is the first differential pressure. The first calculation formula that obtains the flow rate from the above and includes the time change term of the flow rate, and the second calculation formula that obtains the flow rate from the second differential pressure and includes the time change term of the flow rate. It is characterized by eliminating the time-varying term of the flow rate, which is a common term.
　この差圧式流量計であれば、流路における第１の差圧及び第２の差圧を検出し、第１の差圧から流量を求めるものであって流量の時間変化項を含む第１演算式と、第２の差圧から流量を求めるものであって流量の時間変化項を含む第２演算式とを用いて共通項である前記流量の時間変化項を消去した演算式により流量を算出しているので、脈動などを伴う非定常流の流量を高精度に測定することができる。また、対称流路部における第１の差圧及び第２の差圧を検出して流量を求めているので、流体が逆方向に流れる場合（流体が逆流する場合）の流量を高精度に求めることができる。 With this differential pressure type flow meter, the first differential pressure and the second differential pressure in the flow path are detected, and the flow rate is obtained from the first differential pressure, and the first calculation including the time change term of the flow rate. The flow rate is calculated by the calculation formula that eliminates the time change term of the flow rate, which is a common term, using the formula and the second calculation formula that obtains the flow rate from the second differential pressure and includes the time change term of the flow rate. Therefore, it is possible to measure the flow rate of unsteady flow accompanied by pulsation with high accuracy. Further, since the flow rate is obtained by detecting the first differential pressure and the second differential pressure in the symmetrical flow path portion, the flow rate when the fluid flows in the opposite direction (when the fluid flows backward) is obtained with high accuracy. be able to.
　第１の差圧検出部及び第２の差圧検出部に接続される導圧管の本数を少なくしつつ、第１の差圧及び第２の差圧を検出するためには、前記対称流路部に連通して前記流体の圧力を受けるとともに上流側から順に配列された第１～第３の導圧管を有し、前記第１の差圧検出部が接続される前記第１～第３の導圧管の組み合わせと、前記第２の差圧検出部が接続される前記第１～第３の導圧管の組み合わせとが互いに異なることが望ましい。 In order to detect the first differential pressure and the second differential pressure while reducing the number of pressure guiding tubes connected to the first differential pressure detecting unit and the second differential pressure detecting unit, the symmetric flow path is described. The first to third pressure guiding tubes that communicate with each other to receive the pressure of the fluid and are arranged in order from the upstream side, and the first differential pressure detecting unit is connected to the first to third pressure guiding tubes. It is desirable that the combination of the pressure guiding tubes and the combination of the first to third pressure guiding tubes to which the second differential pressure detecting unit is connected are different from each other.
　第１～第３の導圧管の配置に対称性を持たせることにより、流路において流体が順方向に流れる場合と逆方向に流れる場合との両方において同じ測定精度で流量を測定できるようにするためには、前記第１の導圧管と前記第２の導圧管との距離と、前記第２の導圧管と前記第３の導圧管との距離が同一であることが望ましい。 By providing symmetry in the arrangement of the first to third pressure guiding tubes, it is possible to measure the flow rate with the same measurement accuracy in both the case where the fluid flows in the forward direction and the case where the fluid flows in the reverse direction in the flow path. Therefore, it is desirable that the distance between the first pressure guiding tube and the second pressure guiding tube is the same as the distance between the second pressure guiding tube and the third pressure guiding tube.
　前記第１の導圧管は、前記対称流路部において上流側を向いて開口しており、前記第３の導圧管は、前記対称流路部において下流側を向いて開口しており、前記第２の導圧管は、前記対称流路部を形成する管壁に開口していることが望ましい。
　この構成であれば、流路において流体が順方向に流れる場合には、第１の導圧管が流体の全圧を受けることになり、第２の導圧管及び第３の導圧管が流体の静圧を受けることになる。また、流路に流体が逆方向にながれる場合には、第３の導圧管が流体の全圧を受けることになり、第１の導圧管及び第２の導圧管が流体の静圧を受けることになる。これにより、ピトー管式流量計において、脈動及び逆流などを伴う非定常流の流量を高精度に測定することができる。 The first pressure guiding tube is open toward the upstream side in the symmetrical flow path portion, and the third pressure guiding tube is open toward the downstream side in the symmetrical flow path portion. It is desirable that the pressure guiding tube 2 is open to the tube wall forming the symmetrical flow path portion.
With this configuration, when the fluid flows in the forward direction in the flow path, the first pressure guiding tube receives the total pressure of the fluid, and the second pressure guiding tube and the third pressure guiding tube are static of the fluid. You will be under pressure. Further, when the fluid flows in the reverse direction in the flow path, the third pressure guiding tube receives the total pressure of the fluid, and the first pressure guiding tube and the second pressure guiding tube receive the static pressure of the fluid. become. This makes it possible to measure the flow rate of unsteady flow accompanied by pulsation and backflow with high accuracy in the Pitot tube type flow meter.
　上述した第１演算式及び第２演算式の具体例としては、前記第１演算式は、以下の式（１）であり、前記第２演算式は、以下の式（２）である。 As a specific example of the above-mentioned first calculation formula and second calculation formula, the first calculation formula is the following formula (1), and the second calculation formula is the following formula (2).
Figure JPOXMLDOC01-appb-I000004
　この式（１）において、Ｃ１は、第１の差圧を計測する導圧管の距離とその部分の流路形状変化に関係する係数であり、ρは、流体の密度であり、ΔＰ１は、第１の差圧であり、Ｋ１は、第１の差圧を検出する流路部分における差圧と流量の関係から求まる係数である。
Figure JPOXMLDOC01-appb-I000004
In this equation (1), C 1 is a coefficient related to the distance of the pressure guiding tube for measuring the first differential pressure and the change in the shape of the flow path of the portion, ρ is the density of the fluid, and ΔP 1 is. , The first differential pressure, and K 1 is a coefficient obtained from the relationship between the differential pressure and the flow rate in the flow path portion where the first differential pressure is detected.
Figure JPOXMLDOC01-appb-I000005
　この式（２）において、Ｃ２は、第２の差圧を計測する導圧管の距離とその部分の流路形状変化に関係する係数であり、ρは、流体の密度であり、ΔＰ２は、第２の差圧であり、Ｋ２は、第２の差圧を検出する流路部分における差圧と流量の関係から求まる係数である。
Figure JPOXMLDOC01-appb-I000005
In this equation (2), C 2 is a coefficient related to the distance of the pressure guiding tube for measuring the second differential pressure and the change in the shape of the flow path of the portion, ρ is the density of the fluid, and ΔP 2 is. , The second differential pressure, and K 2 is a coefficient obtained from the relationship between the differential pressure and the flow rate in the flow path portion where the second differential pressure is detected.
　上記の第１演算式及び第２演算式を用いて時間変化項を消去した演算式は、以下の式（３）であり、前記流量算出部は、以下の式（３）を用いて、前記第１の差圧及び前記第２の差圧から流量を算出することが考えられる。 The calculation formula in which the time change term is eliminated by using the first calculation formula and the second calculation formula is the following formula (3), and the flow rate calculation unit uses the following formula (3). It is conceivable to calculate the flow rate from the first differential pressure and the second differential pressure.
Figure JPOXMLDOC01-appb-I000006
　この式（３）において、αはＣ２／Ｃ１である。
Figure JPOXMLDOC01-appb-I000006
In this equation (3), α is C 2 / C 1 .
　また、本発明に係る流量算出方法は、所定の基準位置から上流側及び下流側に対称である対称流路部を流れる流体の差圧を検出し、その差圧から前記流体の流量を算出する流量算出方法であって、前記対称流路部における第１の差圧を検出し、前記対称流路部における第２の差圧を検出し、前記第１の差圧及び前記第２の差圧から所定の演算式を用いて流量を算出するものであり、前記所定の演算式として、前記第１の差圧から流量を求めるものであって前記流量の時間変化項を含む第１演算式と、前記第２の差圧から流量を求めるものであって前記流量の時間変化項を含む第２演算式とを用いて、共通項である前記流量の時間変化項を消去したものを用いることを特徴とする。 Further, the flow rate calculation method according to the present invention detects the differential pressure of the fluid flowing through the symmetrical flow path portion symmetrical to the upstream side and the downstream side from the predetermined reference position, and calculates the flow rate of the fluid from the differential pressure. In the flow rate calculation method, the first differential pressure in the symmetrical flow path portion is detected, the second differential pressure in the symmetrical flow path portion is detected, and the first differential pressure and the second differential pressure are detected. The flow rate is calculated using a predetermined calculation formula from the above, and as the predetermined calculation formula, the flow rate is obtained from the first differential pressure, and the first calculation formula including the time change term of the flow rate. , The flow rate is obtained from the second differential pressure, and the one in which the time change term of the flow rate, which is a common term, is eliminated by using the second calculation formula including the time change term of the flow rate is used. It is a feature.
　さらに、本発明に係る差圧式流量計を用いて排ガスの流量を測定する排ガス分析方法も本発明の一態様である。 Further, an exhaust gas analysis method for measuring the flow rate of exhaust gas using the differential pressure type flow meter according to the present invention is also one aspect of the present invention.
　その上、本発明に係る差圧式流量計に用いられるプログラムは、所定の基準位置から上流側及び下流側に対称である対称流路部を流れる流体の第１の差圧を検出する第１の差圧検出部、及び、前記対称流路部を流れる流体の第２の差圧を検出する第２の差圧検出部を備え、それら差圧から前記流体の流量を算出する差圧式流量計に用いられるプログラムであって、前記第１の差圧及び前記第２の差圧から所定の演算式を用いて流量を算出する流量算出部としての機能をコンピュータに備えさせるものであり、前記所定の演算式は、前記第１の差圧から流量を求めるものであって前記流量の時間変化項を含む第１演算式と、前記第２の差圧から流量を求めるものであって前記流量の時間変化項を含む第２演算式とを用いて、共通項である前記流量の時間変化項を消去したものであることを特徴とする。 Moreover, the program used in the differential pressure flow meter according to the present invention is the first to detect the first differential pressure of the fluid flowing through the symmetrical flow path portion symmetrical to the upstream side and the downstream side from the predetermined reference position. A differential pressure type flow meter having a differential pressure detecting unit and a second differential pressure detecting unit for detecting a second differential pressure of the fluid flowing through the symmetrical flow path portion, and calculating the flow rate of the fluid from the differential pressure. The program to be used is to equip the computer with a function as a flow rate calculation unit for calculating a flow rate from the first differential pressure and the second differential pressure using a predetermined calculation formula, and the predetermined one. The calculation formulas are the first calculation formula that obtains the flow rate from the first differential pressure and includes the time change term of the flow rate, and the calculation formula that obtains the flow rate from the second differential pressure and the time of the flow rate. It is characterized in that the time change term of the flow rate, which is a common term, is eliminated by using the second arithmetic expression including the change term.
　以上に述べた本発明によれば、脈動などの非定常流を伴う流体の流れを高精度に測定することができる。 According to the present invention described above, it is possible to measure the flow of a fluid accompanied by an unsteady flow such as pulsation with high accuracy.
本実施形態に係る排ガス分析装置の構成を示す模式図である。It is a schematic diagram which shows the structure of the exhaust gas analyzer which concerns on this embodiment. 同実施形態のテールパイプアタッチメント部分を主として示す拡大断面図である。It is an enlarged sectional view mainly showing the tail pipe attachment part of the same embodiment. 従来の差圧式流量計と本実施形態の差圧式流量計との流量誤差を示す実験結果である。It is an experimental result which shows the flow rate error between the conventional differential pressure type flow meter and the differential pressure type flow meter of this embodiment.
１００・・・排ガス分析装置
２　　・・・差圧式流量計
３　　・・・ガス分析計
２１　・・・取付配管
２２　・・・第１の差圧検出部
２３　・・・第２の差圧検出部
Ｒ　　・・・流路
Ｒ１　・・・対称流路部
２４　・・・流量算出部
２５　・・・第１の導圧管
２６　・・・第２の導圧管
２７　・・・第３の導圧管
７　　・・・排ガスサンプリング部 100 ... Exhaust gas analyzer 2 ... Differential pressure type flow meter 3 ... Gas analyzer 21 ... Mounting piping 22 ... First differential pressure detection unit 23 ... Second differential pressure detection unit R ... Flow path R1 ... Symmetrical flow path section 24 ... Flow rate calculation section 25 ... First pressure guiding tube 26 ... Second pressure guiding tube 27 ... Third pressure guiding tube 7 ...・ ・ Exhaust gas sampling section
　以下に、本発明に係る差圧式流量計を用いた排ガス分析装置の一実施形態について、図面を参照して説明する。 Hereinafter, an embodiment of the exhaust gas analyzer using the differential pressure type flow meter according to the present invention will be described with reference to the drawings.
＜１．装置構成＞
　本実施形態の排ガス分析装置１００は、例えば車両Ｖに搭載されて、当該車両Ｖが路上を走行する際に車両の内燃機関Ｅから排出される排ガスを路上走行中にリアルタイムに分析する車両搭載型のものである。この排ガス分析装置１００は、採取した排ガスを希釈せずに、そのまま濃度測定する直接サンプリング方式のものである。なお、シャシダイナモ上で模擬走行される車両の内燃機関から排出される排ガスを模擬走行中にリアルタイムに分析するものであっても良い。 <1. Device configuration>
The exhaust gas analyzer 100 of the present embodiment is mounted on a vehicle V, for example, and is a vehicle-mounted type that analyzes the exhaust gas discharged from the internal combustion engine E of the vehicle when the vehicle V travels on the road in real time while traveling on the road. belongs to. The exhaust gas analyzer 100 is a direct sampling method that measures the concentration of the collected exhaust gas as it is without diluting it. It should be noted that the exhaust gas emitted from the internal combustion engine of the vehicle simulated on the chassis dynamometer may be analyzed in real time during the simulated traveling.
　具体的にこの排ガス分析装置１００は、図１に示すように、内燃機関Ｅに接続された排気管ＥＨの開口部ＥＨ１に取り付けられて、当該排気管ＥＨから排出される排ガスの流量を測定する差圧式流量計２と、排気管ＥＨから排出される排ガスに含まれる測定対象成分の濃度を測定するためのガス分析計３とを備えている。 Specifically, as shown in FIG. 1, the exhaust gas analyzer 100 is attached to the opening EH1 of the exhaust pipe EH connected to the internal combustion engine E, and measures the flow rate of the exhaust gas discharged from the exhaust pipe EH. It includes a differential pressure type flow meter 2 and a gas analyzer 3 for measuring the concentration of the component to be measured contained in the exhaust gas discharged from the exhaust pipe EH.
　差圧式流量計２は、流路を流れる排ガスの差圧を検出し、その差圧から排ガスの流量を算出するものであって、排気管ＥＨの開口部ＥＨ１に外付けされる取付配管２１と、当該取付配管２１を流れる排ガスの差圧を検出するための第１の差圧検出部２２及び第２の差圧検出部２３とを備えている。なお、差圧式流量計２の詳細は後述する。 The differential pressure type flow meter 2 detects the differential pressure of the exhaust gas flowing through the flow path and calculates the flow rate of the exhaust gas from the differential pressure. A first differential pressure detecting unit 22 and a second differential pressure detecting unit 23 for detecting the differential pressure of the exhaust gas flowing through the mounting pipe 21 are provided. The details of the differential pressure type flow meter 2 will be described later.
　ガス分析計３は、排ガスに含まれる測定対象成分（例えばＣＯ、ＣＯ２、ＮＯＸ、ＴＨＣ等）の濃度を連続測定するものである。なお、ガス分析計３は、ＣＯ、ＣＯ２の濃度を測定するものの場合には、非分散型赤外吸収法（ＮＤＩＲ法）を用いたＮＤＩＲ検出器を用いることができ、ＮＯＸの濃度を測定するものの場合には、化学発光分析法（ＣＬＤ）を用いたＣＬＤ検出器を用いることができ、ＴＨＣの濃度を測定するものの場合には、水素炎イオン化分析法（ＦＩＤ）を用いたＦＩＤ検出器を用いることができる。ガス分析計３は、これらの何れかの検出器を有するものであっても良いし、上記のうち複数種の検出器を有するものであっても良い。その他、ガス分析計３は、測定対象成分に応じて種々の分析法を用いた検出器とすることができる。 The gas analyzer 3 continuously measures the concentration of the measurement target component (for example, CO, CO 2 , NO X , THC, etc.) contained in the exhaust gas. When the gas analyzer 3 measures the CO and CO 2 concentrations, an NDIR detector using a non-dispersive infrared absorption method (NDIR method) can be used to measure the NO X concentration. In the case of measuring, a CLD detector using a chemical emission analysis method (CLD) can be used, and in the case of measuring a THC concentration, FID detection using a hydrogen flame ionization analysis method (FID) can be used. A vessel can be used. The gas analyzer 3 may have any of these detectors, or may have a plurality of types of detectors among the above. In addition, the gas analyzer 3 can be a detector using various analytical methods depending on the component to be measured.
　そして、このガス分析計３には、サンプリングした排ガスを導入するための導入配管６が接続されている。導入配管６の一端部はガス分析計３に接続されており、導入配管６の他端部には、排ガスをサンプリングする排ガスサンプリング部７が設けられている。排ガスサンプリング部７は、上述した差圧式流量計の取付配管２１に設けられている。この排ガスサンプリング部７は、取付配管２１を流れる排ガスの一部を採取するサンプリング管により構成されている。なお、排ガスサンプリング部７は、取付配管２１において、第１、第２の差圧検出部２２、２３よりも下流側に設けられており、第１、第２の差圧検出部２２、２３の差圧検出に圧力変動などの影響を与えないようにしている。 Then, an introduction pipe 6 for introducing the sampled exhaust gas is connected to the gas analyzer 3. One end of the introduction pipe 6 is connected to the gas analyzer 3, and the other end of the introduction pipe 6 is provided with an exhaust gas sampling unit 7 for sampling exhaust gas. The exhaust gas sampling unit 7 is provided in the mounting pipe 21 of the above-mentioned differential pressure type flow meter. The exhaust gas sampling unit 7 is composed of a sampling pipe that collects a part of the exhaust gas flowing through the mounting pipe 21. The exhaust gas sampling unit 7 is provided in the mounting pipe 21 on the downstream side of the first and second differential pressure detecting units 22 and 23, and is provided on the downstream side of the first and second differential pressure detecting units 22 and 23. The differential pressure detection is not affected by pressure fluctuations.
　このガス分析計３により得られた各成分の濃度信号は、上位の演算装置８に送られて、差圧式流量計２の流量算出部２４から出力される流量信号とともに、各成分の排出質量の演算に用いられる。 The concentration signal of each component obtained by the gas analyzer 3 is sent to the upper arithmetic unit 8, and together with the flow rate signal output from the flow rate calculation unit 24 of the differential pressure type flow meter 2, the emission mass of each component is measured. Used for calculation.
＜２．差圧式流量計の詳細構成＞
　差圧式流量計２は、上述した通り、流路を流れる排ガスの差圧を検出し、その差圧から排ガスの流量を算出するものであって、図１及び図２に示すように、排気管ＥＨの開口部ＥＨ１に外付けされる取付配管２１と、当該取付配管２１を流れる排ガスの差圧を検出するための第１の差圧検出部２２及び第２の差圧検出部２３とを備えている。 <2. Detailed configuration of differential pressure type flow meter>
As described above, the differential pressure type flow meter 2 detects the differential pressure of the exhaust gas flowing through the flow path and calculates the flow rate of the exhaust gas from the differential pressure. As shown in FIGS. 1 and 2, the exhaust pipe A mounting pipe 21 externally attached to the opening EH1 of the EH, and a first differential pressure detecting unit 22 and a second differential pressure detecting unit 23 for detecting the differential pressure of the exhaust gas flowing through the mounting pipe 21 are provided. ing.
　取付配管２１は、排気管ＥＨの開口部ＥＨ１の外側周面を覆うように取り付けられる直管形状をなすものである。本実施形態では、断面円形状をなす円管である。そして、取付配管２１の一端開口部が排気管ＥＨの開口部ＥＨ１に装着されるとともに、他端開口部は開放されており、当該他端開口部から排ガスが外部に排出される。 The mounting pipe 21 has a straight pipe shape that is mounted so as to cover the outer peripheral surface of the opening EH1 of the exhaust pipe EH. In the present embodiment, it is a circular tube having a circular cross section. Then, one end opening of the mounting pipe 21 is attached to the opening EH1 of the exhaust pipe EH, and the other end opening is open, and the exhaust gas is discharged to the outside from the other end opening.
　第１の差圧検出部２２は、取付配管２１における流路Ｒの排ガスの全圧と静圧との差圧である第１の差圧ΔＰ１を検出するものである。また、第２の差圧検出部２３は、取付配管２１における流路Ｒの排ガスの全圧と静圧との差圧である第２の差圧ΔＰ２を検出するものである。また、第１の差圧検出部２２により検出される第１の差圧ΔＰ１と、第２の差圧検出部２３により検出される第２の差圧ΔＰ２とは、取付配管２１の流路における互いに異なる位置間の差圧である。 The first differential pressure detecting unit 22 detects the first differential pressure ΔP 1 , which is the differential pressure between the total pressure and the static pressure of the exhaust gas in the flow path R in the mounting pipe 21. Further, the second differential pressure detecting unit 23 detects the second differential pressure ΔP 2 , which is the differential pressure between the total pressure and the static pressure of the exhaust gas in the flow path R in the mounting pipe 21. Further, the first differential pressure ΔP 1 detected by the first differential pressure detecting unit 22 and the second differential pressure ΔP 2 detected by the second differential pressure detecting unit 23 are the flows of the mounting pipe 21. The differential pressure between different positions on the road.
　ここで、取付配管２１の流路Ｒは、所定の基準位置から上流側及び下流側に対称である対称流路部Ｒ１を有している。本実施形態では、取付配管２１が直管形状をなすことから、基準位置は取付配管２１の軸方向中央位置となり、取付配管２１の流路Ｒ全体が対称流路部Ｒ１を構成する。つまり、第１の差圧検出部２２及び第２の差圧検出部２３は、対称流路部Ｒ１における互いに異なる位置間の差圧を検出することになる。 Here, the flow path R of the mounting pipe 21 has a symmetrical flow path portion R1 that is symmetrical to the upstream side and the downstream side from a predetermined reference position. In the present embodiment, since the mounting pipe 21 has a straight pipe shape, the reference position is the axial center position of the mounting pipe 21, and the entire flow path R of the mounting pipe 21 constitutes the symmetrical flow path portion R1. That is, the first differential pressure detecting unit 22 and the second differential pressure detecting unit 23 detect the differential pressure between different positions in the symmetrical flow path portion R1.
　そして、第１の差圧検出部２２及び第２の差圧検出部２３は、図２に示すように、対称流路部Ｒ１に設けられた第１～第３の導圧管２５～２７に接続されることにより、対称流路部Ｒ１における第１の差圧ΔＰ１及び第２の差圧ΔＰ２を検出する。 Then, as shown in FIG. 2, the first differential pressure detecting unit 22 and the second differential pressure detecting unit 23 are connected to the first to third pressure guiding tubes 25 to 27 provided in the symmetrical flow path portion R1. By doing so, the first differential pressure ΔP 1 and the second differential pressure ΔP 2 in the symmetrical flow path portion R1 are detected.
　具体的に第１～第３の導圧管２５～２７は、対称流路部Ｒ１に連通して流体の圧力を受けるとともに上流側からこの順に配列されている。本実施形態では、第１の導圧管２５は、取付配管２１の流路Ｒ（対称流路部Ｒ１）において上流側（一端開口部側）を向いて開口している。これにより、第１の導圧管２５は、排ガスが順方向に流れる場合には、排ガスの全圧を検出するものとなり、排ガスが逆方向に流れる場合には、排ガスの静圧を検出するものとなる。また、第２の導圧管２６は、対称流路部Ｒ１を形成する管壁（取付配管２１の管壁）に流路内側（取付配管２１の中心軸側）を向いて開口している。これにより、第２の導圧管２６は、排ガスの流れる方向（順方向及び逆方向）に関わらず、排ガスの静圧を検出するものとなる。さらに、第３の導圧管２７は、取付配管２１の流路Ｒ（対称流路部Ｒ１）において下流側（他端開口部側）を向いて開口している。これにより、第３の導圧管２７は、排ガスが順方向に流れる場合には、排ガスの静圧を検出するものとなり、排ガスが逆方向に流れる場合には、排ガスの全圧を検出するものとなる。 Specifically, the first to third pressure guiding tubes 25 to 27 communicate with the symmetrical flow path portion R1 to receive the pressure of the fluid and are arranged in this order from the upstream side. In the present embodiment, the first pressure guiding pipe 25 is opened toward the upstream side (one end opening side) in the flow path R (symmetrical flow path portion R1) of the mounting pipe 21. As a result, the first pressure guiding tube 25 detects the total pressure of the exhaust gas when the exhaust gas flows in the forward direction, and detects the static pressure of the exhaust gas when the exhaust gas flows in the opposite direction. Become. Further, the second pressure guiding pipe 26 is open to the pipe wall (tube wall of the mounting pipe 21) forming the symmetrical flow path portion R1 toward the inside of the flow path (center axis side of the mounting pipe 21). As a result, the second pressure guiding tube 26 detects the static pressure of the exhaust gas regardless of the direction in which the exhaust gas flows (forward and reverse directions). Further, the third pressure guiding pipe 27 is opened toward the downstream side (the other end opening side) in the flow path R (symmetrical flow path portion R1) of the mounting pipe 21. As a result, the third pressure guiding tube 27 detects the static pressure of the exhaust gas when the exhaust gas flows in the forward direction, and detects the total pressure of the exhaust gas when the exhaust gas flows in the reverse direction. Become.
　そして、第１の導圧管２５と第２の導圧管２６との距離Ｌ１と、第２の導圧管２６と第３の導圧管２７との距離Ｌ２が同一となるように配列されている。ここで、各導圧管２５～２７の間の距離は、各導圧管２５～２７の圧力計測用の開口の間の距離である。第１～第３の導圧管２５～２７の周方向の位置関係は直線上でなくても良く、周方向において互いに異なる位置であっても良い。 Then, the distance L1 between the first pressure guiding tube 25 and the second pressure guiding tube 26 and the distance L2 between the second pressure guiding tube 26 and the third pressure guiding tube 27 are arranged so as to be the same. Here, the distance between the pressure guiding tubes 25 to 27 is the distance between the pressure measuring openings of the pressure guiding tubes 25 to 27. The positional relationship of the first to third pressure guiding tubes 25 to 27 in the circumferential direction does not have to be on a straight line, and may be different positions in the circumferential direction.
　また、これら第１～第３の導圧管２５～２７を用いて互いに異なる位置間の差圧を検出するために、第１の差圧検出部２２が接続される第１～第３の導圧管２５～２７の組み合わせと、第２の差圧検出部２３が接続される第１～第３の導圧管２５～２７の組み合わせとが互いに異なるように構成されている。本実施形態では、第１の差圧検出部２２は、第１の導圧管２５及び第３の導圧管２７に接続されており、第２の差圧検出部２３は、第１の導圧管２５及び第２の導圧管２６に接続されている。 Further, in order to detect the differential pressure between different positions using the first to third pressure guiding tubes 25 to 27, the first to third pressure guiding tubes to which the first differential pressure detecting unit 22 is connected are connected. The combination of 25 to 27 and the combination of the first to third pressure guiding tubes 25 to 27 to which the second differential pressure detecting unit 23 is connected are configured to be different from each other. In the present embodiment, the first differential pressure detecting unit 22 is connected to the first pressure guiding tube 25 and the third pressure guiding tube 27, and the second differential pressure detecting unit 23 is the first pressure guiding tube 25. And is connected to the second pressure guiding tube 26.
　そして、差圧式流量計２の流量算出部２４は、第１の差圧検出部２２により得られた第１の差圧ΔＰ１及び第２の差圧検出部２３により得られた第２の差圧ΔＰ２から、所定の演算式を用いて排ガスの体積流量Ｑを算出する。 Then, the flow rate calculation unit 24 of the differential pressure type flow meter 2 has a second difference obtained by the first differential pressure ΔP 1 obtained by the first differential pressure detecting unit 22 and the second differential pressure detecting unit 23. From the pressure ΔP 2 , the volumetric flow rate Q of the exhaust gas is calculated using a predetermined calculation formula.
　ここで、所定の演算式は、第１の差圧ΔＰ１から流量を求めるものであって体積流量Ｑの時間変化項ｄＱ／ｄｔを含む第１演算式と、第２の差圧ΔＰ２から体積流量Ｑを求めるものであって体積流量Ｑの時間変化項ｄＱ／ｄｔを含む第２演算式とを用いて、共通項である体積流量Ｑの時間変化項ｄＱ／ｄｔを消去したものである。 Here, the predetermined calculation formula is for obtaining the flow rate from the first differential pressure ΔP 1 , and is derived from the first calculation formula including the time change term dQ / dt of the volume flow rate Q and the second differential pressure ΔP 2 . The time change term dQ / dt of the volume flow rate Q, which is a common term, is eliminated by using the second arithmetic expression that obtains the volume flow rate Q and includes the time change term dQ / dt of the volume flow rate Q. ..
　第１演算式は、以下の式（１）により示されるものである。 The first arithmetic expression is represented by the following expression (1).
Figure JPOXMLDOC01-appb-I000007
　この式（１）において、Ｃ１は、第１の差圧ΔＰ１を検出する流路部分の流路断面積の変化を示す係数であり、ρは、流体の密度であり、Ｋ１は、第１の差圧ΔＰ１を検出する流路部分における差圧と流量との関係から求まる損失係数（例えば、流体中のせん断、乱流エネルギー散逸などに起因する損失の係数）である。なお、前記損失係数は、定常流実験の結果に基づいて設定される。
Figure JPOXMLDOC01-appb-I000007
In this equation (1), C 1 is a coefficient indicating a change in the flow path cross-sectional area of the flow path portion for detecting the first differential pressure ΔP 1 , ρ is the fluid density, and K 1 is. It is a loss coefficient (for example, a coefficient of loss due to shear in a fluid, turbulent energy dissipation, etc.) obtained from the relationship between the differential pressure and the flow rate in the flow path portion where the first differential pressure ΔP 1 is detected. The loss coefficient is set based on the result of the steady flow experiment.
　第２演算式は、以下の式（２）により示されるものである。 The second arithmetic expression is expressed by the following expression (2).
Figure JPOXMLDOC01-appb-I000008
　この式（２）において、Ｃ２は、第２の差圧ΔＰ２を検出する流路部分の流路断面積の変化を示す係数であり、ρは、流体の密度であり、Ｋ２は、第２の差圧ΔＰ２を検出する流路部分における定常流実験などにより、差圧と流量との関係から実験的に求まる損失係数（例えば、流体中のせん断、乱流エネルギー散逸などに起因する損失の係数）である。なお、前記損失係数は、定常流実験の結果に基づいて設定される。
Figure JPOXMLDOC01-appb-I000008
In this equation (2), C 2 is a coefficient indicating a change in the flow path cross-sectional area of the flow path portion for detecting the second differential pressure ΔP 2 , ρ is the fluid density, and K 2 is. It is caused by the loss coefficient (for example, shear in the fluid, turbulent energy dissipation, etc.) that can be experimentally obtained from the relationship between the differential pressure and the flow rate by a steady flow experiment in the flow path portion where the second differential pressure ΔP 2 is detected. Loss coefficient). The loss coefficient is set based on the result of the steady flow experiment.
　具体的に流量算出部２４は、上記の式（１）及び式（２）から時間変化項ｄＱ／ｄｔを消去した所定の演算式である以下の式（３）を用いて、第１の差圧ΔＰ１及び第２の差圧ΔＰ２から体積流量Ｑを算出する。 Specifically, the flow rate calculation unit 24 uses the following equation (3), which is a predetermined arithmetic equation in which the time change term dQ / dt is eliminated from the above equations (1) and (2), and the first difference is obtained. The volume flow rate Q is calculated from the pressure ΔP 1 and the second differential pressure ΔP 2 .
Figure JPOXMLDOC01-appb-I000009
　この式（３）において、αはＣ２／Ｃ１である。
Figure JPOXMLDOC01-appb-I000009
In this equation (3), α is C 2 / C 1 .
　次に、従来の差圧式流量計と本実施形態の差圧式流量計との流量誤差の実験結果を図３に示す。なお、従来の差圧式流量計の流量算出方法は上述している。 Next, FIG. 3 shows the experimental results of the flow rate error between the conventional differential pressure type flow meter and the differential pressure type flow meter of the present embodiment. The flow rate calculation method of the conventional differential pressure type flow meter is described above.
　この実験においては、流路を構成する配管の管径を、φ２８ｍｍ（Ａ）、φ５６ｍｍ（Ｂ）の２つを用意し、φ２８ｍｍ（Ａ）においては、流れるガスの振動周期を０．１５ｓ（１）又は０．０６ｓ（２）とし、φ５６ｍｍ（Ｂ）においては、流れるガスの振動周期を０．１５ｓ（１）とした。なお、振動周期０．１５ｓは、単気筒エンジンの回転数９００ｒｐｍに相当し、振動周期０．０６ｓは、単気筒エンジンの回転数２０００ｒｐｍに相当する。 In this experiment, two pipe diameters of φ28 mm (A) and φ56 mm (B) were prepared for the pipes constituting the flow path, and in φ28 mm (A), the vibration cycle of the flowing gas was 0.15 s (1). ) Or 0.06s (2), and in φ56 mm (B), the vibration cycle of the flowing gas was 0.15s (1). The vibration cycle of 0.15 s corresponds to the rotation speed of the single cylinder engine of 900 rpm, and the vibration cycle of 0.06 s corresponds to the rotation speed of the single cylinder engine of 2000 rpm.
　図３から明らかなように、本実施形態の差圧式流量計の平均誤差は、従来の差圧式流量計の平均誤差よりも小さくなっていることが分かる。 As is clear from FIG. 3, it can be seen that the average error of the differential pressure type flow meter of the present embodiment is smaller than the average error of the conventional differential pressure type flow meter.
＜３．従来の差圧式流量計＞
　なお、上述した従来の差圧式流量計は、１つの差圧検出部により得られた差圧ΔＰと、排ガス温度Ｔｅｘｈ（ｔ）［Ｋ］と、排ガス圧力Ｐｅｘｈ（ｔ）［ｋＰａ］とから、以下の式により、基準とする状態における排ガスの体積流量Ｑｅｘｈ（ｔ）［ｍ３／ｍｉｎ］を算出するものである。 <3. Conventional differential pressure type flow meter>
In the conventional differential pressure type flow meter described above, the differential pressure ΔP obtained by one differential pressure detection unit, the exhaust gas temperature Texh (t) [K], and the exhaust gas pressure Pexh (t) [kPa] are used. Therefore, the volumetric flow rate Qex (t) [m 3 / min] of the exhaust gas in the reference state is calculated by the following formula.
Figure JPOXMLDOC01-appb-I000010
　ここで、ｋ：比例係数
　　　　　Ｐ０：標準圧力（１０１．３［ｋＰａ］）
　　　　　Ｔ０：標準温度（２９３．１５［Ｋ］）
　　　　　ρｅｘｈ：標準状態における排ガス密度［ｇ／ｍ３］
Figure JPOXMLDOC01-appb-I000010
Here, k: proportional coefficient P 0 : standard pressure (101.3 [kPa])
T 0 : Standard temperature (293.15 [K])
ρ exh : Exhaust gas density in standard state [g / m 3 ]
＜４．本実施形態の効果＞
　このように構成した本実施形態の排ガス分析装置１００によれば、流路Ｒにおける第１の差圧ΔＰ１及び第２の差圧ΔＰ２を検出し、第１の差圧ΔＰ１から体積流量Ｑを求めるものであって体積流量Ｑの時間変化項ｄＱ／ｄｔを含む第１演算式と、第２の差圧ΔＰ２から体積流量Ｑを求めるものであって体積流量Ｑの時間変化項ｄＱ／ｄｔを含む第２演算式とを用いて共通項である体積流量Ｑの時間変化項ｄＱ／ｄｔを消去した演算式により体積流量Ｑを算出しているので、脈動などを伴う非定常流の流量Ｑを高精度に測定することができる。 <4. Effect of this embodiment>
According to the exhaust gas analyzer 100 of the present embodiment configured as described above, the first differential pressure ΔP 1 and the second differential pressure ΔP 2 in the flow path R are detected, and the volume flow rate is increased from the first differential pressure ΔP 1 . The first calculation formula including the time change term dQ / dt of the volume flow rate Q, which obtains Q, and the time change term dQ of the volume flow rate Q, which obtains the volume flow rate Q from the second differential pressure ΔP2. Since the volume flow rate Q is calculated by the calculation formula in which the time change term dQ / dt of the volume flow rate Q, which is a common term, is eliminated by using the second calculation formula including / dt, the unsteady flow accompanied by pulsation or the like is calculated. The flow rate Q can be measured with high accuracy.
　また、第１の差圧検出部２２及び第２の差圧検出部２３は、対称流路部Ｒ１における互いに異なる位置の差圧を検出するので、流路Ｒにおいて流体が逆方向に流れる場合（流体が逆流する場合）の体積流量Ｑを高精度に求めることができる。 Further, since the first differential pressure detecting unit 22 and the second differential pressure detecting unit 23 detect the differential pressures at different positions in the symmetrical flow path portion R1, when the fluid flows in the opposite direction in the flow path R ( The volumetric flow rate Q (when the fluid flows backward) can be obtained with high accuracy.
　さらに、第１の導圧管２５と第２の導圧管２６との距離Ｌ１と、第２の導圧管２６と第３の導圧管２７との距離Ｌ２を同一として、第１～第３の導圧管２５～２７の配置に対称性を持たせているので、流路Ｒにおいて流体が順方向に流れる場合と逆方向に流れる場合との両方において同じ測定精度で流量を測定することができる。 Further, the distance L1 between the first pressure guiding tube 25 and the second pressure guiding tube 26 and the distance L2 between the second pressure guiding tube 26 and the third pressure guiding tube 27 are the same, and the first to third pressure guiding tubes are the same. Since the arrangement of 25 to 27 has symmetry, the flow rate can be measured with the same measurement accuracy in both the case where the fluid flows in the forward direction and the case where the fluid flows in the reverse direction in the flow path R.
　第１の導圧管２５は対称流路部Ｒ１において上流側を向いて開口しており、第３の導圧管２７は対称流路部Ｒ１において下流側を向いて開口しており、第２の導圧管２６は対称流路部Ｒ１を形成する管壁に開口しているので、流路Ｒにおいて流体が順方向に流れる場合には、第１の導圧管２５が流体の全圧を受けることになり、第２の導圧管２６及び第３の導圧管２７が流体の静圧を受けることになる。また、流路に流体が逆方向にながれる場合には、第３の導圧管２７が流体の全圧を受けることになり、第１の導圧管２５及び第２の導圧管２６が流体の静圧を受けることになる。これにより、ピトー管式流量計において、脈動及び逆流などを伴う非定常流の体積流量Ｑを高精度に測定することができる。 The first pressure guiding tube 25 is open toward the upstream side in the symmetric flow path portion R1, and the third pressure guiding tube 27 is open toward the downstream side in the symmetric flow path portion R1. Since the pressure tube 26 is open to the tube wall forming the symmetrical flow path portion R1, when the fluid flows in the forward direction in the flow path R, the first pressure guiding tube 25 receives the total pressure of the fluid. , The second pressure guiding tube 26 and the third pressure guiding tube 27 receive the static pressure of the fluid. Further, when the fluid flows in the reverse direction in the flow path, the third pressure guiding tube 27 receives the total pressure of the fluid, and the first pressure guiding tube 25 and the second pressure guiding tube 26 receive the static pressure of the fluid. Will receive. As a result, the volumetric flow rate Q of the unsteady flow accompanied by pulsation and backflow can be measured with high accuracy in the Pitot tube type flow meter.
＜５．その他の実施形態＞
　なお、本発明は前記実施形態に限られるものではない。 <5. Other embodiments>
The present invention is not limited to the above embodiment.
　例えば、各差圧検出部２２、２３が接続される第１～第３の導圧管２５～２７の組み合わせは、前記実施形態に限られず、その他の組み合わせであってもよい。 For example, the combination of the first to third pressure guiding tubes 25 to 27 to which the differential pressure detecting units 22 and 23 are connected is not limited to the above embodiment, and may be other combinations.
　また、導圧管は３つに限られず、第１の差圧検出部２２に専用の２つの導圧管を設け、第２の差圧検出部２３に専用の２つの導圧管を設けてもよい。 Further, the number of pressure guiding tubes is not limited to three, and the first differential pressure detecting unit 22 may be provided with two dedicated pressure guiding tubes, and the second differential pressure detecting unit 23 may be provided with two dedicated pressure guiding tubes.
　さらに、前記実施形態では、取付配管の流路全体が対称流路部を構成していたが、取付配管の流路の一部が対称流路部を構成するものであってもよい。 Further, in the above-described embodiment, the entire flow path of the mounting pipe constitutes the symmetrical flow path portion, but a part of the flow path of the mounting pipe may form the symmetrical flow path portion.
　加えて、第１の導圧管２５と第２の導圧管２６との距離Ｌ１と、第２の導圧管２６と第３の導圧管２７との距離Ｌ２が同一でなく、第１～第３の導圧管２５～２７を非対称に配置しても良い。この場合、各導圧管２５～２７の配置の自由度を増すことができる。例えば、上述した式（３）におけるΔＰ１－ΔＰ２／αの値がゼロ又は限りなく小さくなる条件において、それぞれの導体管２５～２７の配置を再検討することで測定精度を向上させることが可能になる。 In addition, the distance L1 between the first pressure guiding tube 25 and the second pressure guiding tube 26 and the distance L2 between the second pressure guiding tube 26 and the third pressure guiding tube 27 are not the same, and the first to third pressure guiding tubes 26 are not the same. The pressure guiding tubes 25 to 27 may be arranged asymmetrically. In this case, the degree of freedom in arranging the pressure guiding tubes 25 to 27 can be increased. For example, under the condition that the value of ΔP1-ΔP2 / α in the above-mentioned equation (3) becomes zero or infinitely small, it is possible to improve the measurement accuracy by reexamining the arrangement of the respective conductor tubes 25 to 27. Become.
　その上、前記実施形態では、２つの差圧検出部２２、２３を有する構成について説明したが、３つ以上の差圧検出部を有するものであっても良い。 Moreover, in the above-described embodiment, the configuration having the two differential pressure detection units 22 and 23 has been described, but the configuration may have three or more differential pressure detection units.
　前記実施形態では、第１の導圧管２５及び第３の導圧管２７を互いに独立して配置しているが、１つの導圧管の内部に第１の導圧管２５の機能を果たす導圧流路と、第３の導体管２７の機能を果たす導圧流路とを形成してもよい。この構成であれば、取付配管２１の流路内の構成を簡単にすることができる。 In the above embodiment, the first pressure guiding tube 25 and the third pressure guiding tube 27 are arranged independently of each other, but inside one pressure guiding tube, there is a pressure guiding flow path that functions as the first pressure guiding tube 25. , A pressure guiding channel that functions as a third conductor tube 27 may be formed. With this configuration, the configuration in the flow path of the mounting pipe 21 can be simplified.
　その上、前記実施形態では、差圧式流量計を排ガス分析装置に適用した場合を説明したが、その他の分析装置に適用しても良いし、差圧式流量計単体で使用するものであっても良い。 Further, in the above-described embodiment, the case where the differential pressure type flow meter is applied to the exhaust gas analyzer has been described, but the differential pressure type flow meter may be applied to other analyzers, or the differential pressure type flow meter may be used alone. good.
　その他、本発明の趣旨に反しない限りにおいて様々な実施形態の変形や組み合わせを行っても構わない。 In addition, various modifications and combinations may be made as long as it does not contradict the gist of the present invention.
　本発明によれば、脈動などの非定常流を伴う流体の流れを高精度に測定することができる。

  According to the present invention, the flow of a fluid accompanied by an unsteady flow such as pulsation can be measured with high accuracy.

Claims (12)

  1. 　所定の基準位置から上流側及び下流側に対称である対称流路部を流れる流体の差圧を検出し、その差圧から前記流体の流量を算出する差圧式流量計であって、
    　前記対称流路部における第１の差圧を検出する第１の差圧検出部と、
    　前記対称流路部における第２の差圧を検出する第２の差圧検出部と、
    　前記第１の差圧及び前記第２の差圧から所定の演算式を用いて流量を算出する流量算出部とを備え、
    　前記所定の演算式は、前記第１の差圧から流量を求めるものであって前記流量の時間変化項を含む第１演算式と、前記第２の差圧から流量を求めるものであって前記流量の時間変化項を含む第２演算式とを用いて、共通項である前記流量の時間変化項を消去したものである、差圧式流量計。     A differential pressure type flow meter that detects the differential pressure of a fluid flowing through a symmetrical flow path portion that is symmetrical to the upstream side and the downstream side from a predetermined reference position, and calculates the flow rate of the fluid from the differential pressure.
    A first differential pressure detecting unit that detects a first differential pressure in the symmetrical flow path portion, and a
    A second differential pressure detecting unit that detects a second differential pressure in the symmetrical flow path portion, and a second differential pressure detecting unit.
    It is provided with a flow rate calculation unit that calculates a flow rate from the first differential pressure and the second differential pressure using a predetermined calculation formula.
    The predetermined calculation formula is for obtaining the flow rate from the first differential pressure, and is for obtaining the flow rate from the first calculation formula including the time change term of the flow rate and the second differential pressure. A differential pressure type flow meter in which the time change term of the flow rate, which is a common term, is eliminated by using the second arithmetic expression including the time change term of the flow rate.
  2. 　前記対称流路部に連通して前記流体の圧力を受けるとともに上流側から順に配列された第１～第３の導圧管を有し、
    　前記第１の差圧検出部が接続される前記第１～第３の導圧管の組み合わせと、前記第２の差圧検出部が接続される前記第１～第３の導圧管の組み合わせとが互いに異なる、請求項１に記載の差圧式流量計。     It has first to third pressure guiding tubes that communicate with the symmetrical flow path portion, receive the pressure of the fluid, and are arranged in order from the upstream side.
    The combination of the first to third pressure guiding tubes to which the first differential pressure detecting unit is connected and the combination of the first to third pressure guiding tubes to which the second differential pressure detecting unit is connected are The differential pressure type flow meter according to claim 1, which is different from each other.
  3. 　前記第１の導圧管と前記第２の導圧管との距離と、前記第２の導圧管と前記第３の導圧管との距離が同一である、請求項２に記載の差圧式流量計。 The differential pressure type flow meter according to claim 2, wherein the distance between the first pressure guiding tube and the second pressure guiding tube is the same as the distance between the second pressure guiding tube and the third pressure guiding tube.
  4. 　前記第１の導圧管は、前記対称流路部において上流側を向いて開口しており、
    　前記第３の導圧管は、前記対称流路部において下流側を向いて開口しており、
    　前記第２の導圧管は、前記対称流路部を形成する管壁に開口している、請求項２又は３に記載の差圧式流量計。     The first pressure guiding tube is open toward the upstream side in the symmetrical flow path portion.
    The third pressure guiding tube is open toward the downstream side in the symmetrical flow path portion.
    The differential pressure type flow meter according to claim 2 or 3, wherein the second pressure guiding tube is open to a pipe wall forming the symmetrical flow path portion.
  5. 　前記第１演算式は、以下の式（１）であり、前記第２演算式は、以下の式（２）である、請求項１乃至４の何れか一項に記載の差圧式流量計。
    Figure JPOXMLDOC01-appb-M000001
     　この式（１）において、Ｃ１は、第１の差圧を計測する導圧管の距離とその部分の流路形状変化に関係する係数であり、ρは、流体の密度であり、ΔＰ１は、第１の差圧であり、Ｋ１は、第１の差圧を検出する流路部分における差圧と流量の関係から求まる係数である。
    Figure JPOXMLDOC01-appb-M000002
     　この式（２）において、Ｃ２は、第２の差圧を計測する導圧管の距離とその部分の流路形状変化に関係する係数であり、ρは、流体の密度であり、ΔＰ２は、第２の差圧であり、Ｋ２は、第２の差圧を検出する流路部分における差圧と流量の関係から求まる係数である。     The differential pressure type flow meter according to any one of claims 1 to 4, wherein the first calculation formula is the following formula (1), and the second calculation formula is the following formula (2).
    Figure JPOXMLDOC01-appb-M000001
     In this equation (1), C 1 is a coefficient related to the distance of the pressure guiding tube for measuring the first differential pressure and the change in the shape of the flow path of the portion, ρ is the density of the fluid, and ΔP 1 is. , The first differential pressure, and K 1 is a coefficient obtained from the relationship between the differential pressure and the flow rate in the flow path portion where the first differential pressure is detected.
    Figure JPOXMLDOC01-appb-M000002
     In this equation (2), C 2 is a coefficient related to the distance of the pressure guiding tube for measuring the second differential pressure and the change in the shape of the flow path of the portion, ρ is the density of the fluid, and ΔP 2 is. , The second differential pressure, and K 2 is a coefficient obtained from the relationship between the differential pressure and the flow rate in the flow path portion where the second differential pressure is detected.
  6. 　前記流量算出部は、以下の式（３）を用いて、前記第１の差圧及び前記第２の差圧から流量を算出する、請求項５に記載の差圧式流量計。
    Figure JPOXMLDOC01-appb-M000003
     　この式（３）において、αはＣ２／Ｃ１である。     The differential pressure type flow meter according to claim 5, wherein the flow rate calculation unit calculates a flow rate from the first differential pressure and the second differential pressure using the following equation (3).
    Figure JPOXMLDOC01-appb-M000003
     In this equation (3), α is C 2 / C 1 .
  7. 　排気管の開口部に取り付けられて、当該排気管から出る排ガスが流れる流路を形成する取付配管を備え、
    　前記取付配管に前記第１の差圧検出部及び前記第２の差圧検出部が設けられている、請求項１乃至６の何れか一項に記載の差圧式流量計。     It is equipped with a mounting pipe that is attached to the opening of the exhaust pipe and forms a flow path through which the exhaust gas emitted from the exhaust pipe flows.
    The differential pressure type flow meter according to any one of claims 1 to 6, wherein the mounting pipe is provided with the first differential pressure detecting unit and the second differential pressure detecting unit.
  8. 　請求項７に記載の差圧式流量計と、
    　前記排ガスに含まれる所定成分の濃度を測定する排ガス分析計とを備え、
    　前記取付配管には、前記排ガスをサンプリングして前記排ガス分析計に導く排ガスサンプリング部が設けられている、排ガス分析装置。     The differential pressure type flow meter according to claim 7 and
    Equipped with an exhaust gas analyzer that measures the concentration of a predetermined component contained in the exhaust gas.
    An exhaust gas analyzer provided with an exhaust gas sampling unit that samples the exhaust gas and guides the exhaust gas to the exhaust gas analyzer in the mounting pipe.
  9. 　車両搭載型のものである請求項８記載の排ガス分析装置。 The exhaust gas analyzer according to claim 8, which is a vehicle-mounted type.
  10. 　所定の基準位置から上流側及び下流側に対称である対称流路部を流れる流体の差圧を検出し、その差圧から前記流体の流量を算出する流量測定方法であって、
    　前記対称流路部における第１の差圧を検出し、
    　前記対称流路部における第２の差圧を検出し、
    　前記第１の差圧及び前記第２の差圧から所定の演算式を用いて流量を算出するものであり、
    　前記所定の演算式として、前記第１の差圧から流量を求めるものであって前記流量の時間変化項を含む第１演算式と、前記第２の差圧から流量を求めるものであって前記流量の時間変化項を含む第２演算式とを用いて、共通項である前記流量の時間変化項を消去したものを用いる、流量測定方法。     A flow rate measuring method that detects the differential pressure of a fluid flowing through a symmetrical flow path portion that is symmetrical to the upstream side and the downstream side from a predetermined reference position, and calculates the flow rate of the fluid from the differential pressure.
    The first differential pressure in the symmetrical flow path portion is detected, and the pressure is increased.
    The second differential pressure in the symmetrical flow path portion is detected, and the pressure is increased.
    The flow rate is calculated from the first differential pressure and the second differential pressure using a predetermined calculation formula.
    As the predetermined calculation formula, the flow rate is obtained from the first differential pressure, the first calculation formula including the time change term of the flow rate, and the flow rate is obtained from the second differential pressure. A flow rate measuring method using a second arithmetic expression including a time change term of a flow rate and eliminating the time change term of the flow rate, which is a common term.
  11. 　請求項１乃至７の何れか一項に記載の差圧式流量計により排ガスの流量を測定する排ガス分析方法。 An exhaust gas analysis method for measuring the flow rate of exhaust gas by the differential pressure type flow meter according to any one of claims 1 to 7.
  12. 　所定の基準位置から上流側及び下流側に対称である対称流路部を流れる流体の第１の差圧を検出する第１の差圧検出部、及び、前記流路を流れる流体の第２の差圧を検出する第２の差圧検出部を備え、それら差圧から前記流体の流量を算出する差圧式流量計に用いられるプログラムであって、
    　前記第１の差圧及び前記第２の差圧から所定の演算式を用いて流量を算出する流量算出部としての機能をコンピュータに備えさせるものであり、
    　前記所定の演算式は、前記第１の差圧から流量を求めるものであって前記流量の時間変化項を含む第１演算式と、前記第２の差圧から流量を求めるものであって前記流量の時間変化項を含む第２演算式とを用いて、共通項である前記流量の時間変化項を消去したものである、プログラム。     A first differential pressure detecting unit that detects a first differential pressure of a fluid flowing through a symmetrical flow path portion that is symmetrical from a predetermined reference position to the upstream side and a downstream side, and a second differential pressure detecting unit of the fluid flowing through the flow path. It is a program used in a differential pressure type flow meter that has a second differential pressure detection unit that detects the differential pressure and calculates the flow rate of the fluid from the differential pressure.
    The computer is provided with a function as a flow rate calculation unit that calculates a flow rate from the first differential pressure and the second differential pressure using a predetermined calculation formula.
    The predetermined calculation formula is for obtaining the flow rate from the first differential pressure, and is for obtaining the flow rate from the first calculation formula including the time change term of the flow rate and the second differential pressure. A program in which the time-varying term of the flow rate, which is a common term, is eliminated by using the second arithmetic expression including the time-changing term of the flow rate.
PCT/JP2021/034977 2020-10-13 2021-09-24 Differential pressure-type flow meter, exhaust gas analysis device, flow rate measurement method, exhaust gas analysis method, and program for differential pressure-type flow meter WO2022080113A1 (en)

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JPH0618541A (en) * 1991-01-22 1994-01-25 Centre Natl Rech Scient <Cnrs> Method and device for measuring unstationary flow rate
JPH0743183A (en) * 1993-07-27 1995-02-10 Ippei Torigoe Flowmeter
US5736650A (en) * 1995-06-15 1998-04-07 Schlumberger Technology Corp. Venturi flow meter for measurement in a fluid flow passage
JP2011515689A (en) * 2008-03-28 2011-05-19 セントレ・ナショナル・デ・ラ・レシェルシェ・サイエンティフィーク Real-time measurement system for instantaneous fluid flow
JP2014020808A (en) * 2012-07-12 2014-02-03 Isuzu Motors Ltd Pitot tube type flowmeter and flow rate measurement method using the same

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0618541A (en) * 1991-01-22 1994-01-25 Centre Natl Rech Scient <Cnrs> Method and device for measuring unstationary flow rate
JPH0743183A (en) * 1993-07-27 1995-02-10 Ippei Torigoe Flowmeter
US5736650A (en) * 1995-06-15 1998-04-07 Schlumberger Technology Corp. Venturi flow meter for measurement in a fluid flow passage
JP2011515689A (en) * 2008-03-28 2011-05-19 セントレ・ナショナル・デ・ラ・レシェルシェ・サイエンティフィーク Real-time measurement system for instantaneous fluid flow
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