JP2008128739A - Method and instrument for measuring number of fine particles - Google Patents

Method and instrument for measuring number of fine particles Download PDF

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JP2008128739A
JP2008128739A JP2006312076A JP2006312076A JP2008128739A JP 2008128739 A JP2008128739 A JP 2008128739A JP 2006312076 A JP2006312076 A JP 2006312076A JP 2006312076 A JP2006312076 A JP 2006312076A JP 2008128739 A JP2008128739 A JP 2008128739A
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Nobuhiro Yanagisawa
伸浩 柳沢
Keiko Shibata
慶子 柴田
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Isuzu Motors Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To enable measurement of high precision by calculating the charge efficiency of fine particles from an actually measured value to correct the same in a particle number measuring method of fine particles for measuring the number of the fine particle contained in the exhaust gas or the like of an automobile by utilizing a differential type electro-mobility measuring instrument (DMA), a high-sensitivity ammeter and a coagulated nucleus counter (CNC), and a particle number measuring instrument. <P>SOLUTION: Voltage is applied to the classifying electrode 14 of the differential type electro-mobility measuring instrument 2 at a predetermined time interval to count the number Na of particles at the time of application of voltage and the number Nb of the particles at the time of non-application of voltage by the coagulated nucleus counter 4. The number Na of particles calculated from the difference between the numbers of particles Na and Nb is compared with the current value ic calculated by the high-sensitivity ammeter 4 to calculate the charge efficiency fc of the particles of a particle group. The number Nm of the particles detected from the current value im in calculated by the high-sensitivity ammeter 4 is corrected using the charge efficiency fc to calculate the number Nv of the particles of the particle group. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、自動車の排気ガス等に含まれる微小粒子の粒子数を、微分型電気移動度測定装置（ＤＭＡ）と高感度電流計と凝縮核計数器（ＣＮＣ）を利用して、粒子の荷電効率を実測しながら、精度良く測定できる微小粒子の粒子数計測方法及び装置に関する。   In the present invention, the number of fine particles contained in an automobile exhaust gas or the like is calculated by using a differential electric mobility measuring device (DMA), a highly sensitive ammeter, and a condensation nucleus counter (CNC). The present invention relates to a method and apparatus for measuring the number of fine particles that can be measured with high accuracy while actually measuring efficiency.

微小粒子、特にナノ粒子、超微小粒子と呼ばれる１００ｎｍ付近以下の粒子が、ディーゼルエンジン等の内燃機関から放出されており、その粒子数、粒径分布を測定することが環境対策上重要となってきている。   Fine particles, especially nanoparticles of less than 100 nm, called nanoparticles and ultrafine particles, are emitted from internal combustion engines such as diesel engines, and it is important for environmental measures to measure the number of particles and particle size distribution. It is coming.

従来技術の粒径分布測定装置では、ナノ粒子の粒径分布を測定するための分級方法には、微小粒子の慣性衝突を利用した多段インパクターや、電気移動度を利用した微分型電気移動度測定装置（ＤＭＡ：Differential Mobility Analyser) が用いられており、また、粒子数の検出には、電気的検出のエレクトロメータや、光学的検出の凝縮核計数器（ＣＮＣ：Condensation Nucleus Counter）が用いられている。   In the prior art particle size distribution measuring device, the classification method for measuring the particle size distribution of nanoparticles is a multistage impactor using inertial collision of microparticles, or differential electric mobility using electric mobility. A measurement device (DMA: Differential Mobility Analyzer) is used, and for detection of the number of particles, an electrometer for electrical detection and a condensation nucleus counter (CNC) for optical detection are used. ing.

この図４に例示する多段インパクター２０では、入口２１から導入した微小粒子を含むガス（エアロゾル）は、多段（Ｓ１〜ＳＮ）の開口径が各段階によって異なるノズル２２を通して、エアロゾルの流速を変化させながら、気流中の微小粒子の慣性を利用して、各段階のノズル２２に対向して配置された衝突板(Impaction Plate) ２３に慣性衝突させて付着させ、これにより各段階の衝突板２３毎に分級した状態で微小粒子を捕集し、残りの気体は、フィルタ２４を通過した後、出口２５から排出される。   In the multistage impactor 20 illustrated in FIG. 4, the gas (aerosol) containing fine particles introduced from the inlet 21 changes the flow velocity of the aerosol through the nozzles 22 having different multistage (S1 to SN) opening diameters depending on each stage. Then, using the inertia of the microparticles in the air stream, the impact plate 23 is placed on the impact plate 23 disposed opposite to the nozzle 22 at each stage and is made to adhere to the impact plate 23. Fine particles are collected in a classified state every time, and the remaining gas passes through the filter 24 and is then discharged from the outlet 25.

つまり、エアロゾルは、ノズルを通ることにより加速され、粒径の大きな粒子は正面の衝突板へ衝突・捕集され、より小さな粒子はガスと共に衝突板を回り込んで次段の衝突板へ流出して再度同様に分級され、それを多段に繰り返すことにより分級する。   In other words, the aerosol is accelerated by passing through the nozzle, the particles with large particle size collide and collect on the front collision plate, and the smaller particles flow around the collision plate with the gas and flow out to the next collision plate. In the same way, classification is performed again, and classification is performed by repeating it in multiple stages.

しかしながら、この多段インパクターには、１００ｎｍ程度以下の分級は減圧下で行う必要があること、１０ｎｍ程度以下の分級は実用上不可能であること等の欠点がある。また、１０段程度の装置しか実用化されておらず、粒径の分解能が低く、また、装置の仕様により分級の範囲が固定されてしまうという問題がある。そのため、分析の用途に応じて、分級粒径の範囲を変更することは困難となる。   However, this multi-stage impactor has the disadvantages that classification of about 100 nm or less needs to be performed under reduced pressure, and classification of about 10 nm or less is practically impossible. Further, only about 10-stage apparatuses have been put to practical use, and there is a problem that the resolution of the particle size is low and the classification range is fixed depending on the specifications of the apparatus. Therefore, it becomes difficult to change the range of the classified particle size according to the purpose of analysis.

また、ＤＭＡの例としては、エアロゾルを帯電させて、外筒と内筒からなる二重円筒内に導いて、その後両端を封止した後に、外筒に電圧を印加して、内筒に流れる電流を高感度の電流計で測定し、この電流値の変化が電気移動度に対応した情報を与えることを利用して、電気移動度の分布を求め、これに基づいて粒径分布を測定する粒径分布測定装置が提案されている（例えば、特許文献１参照。）。   As an example of DMA, the aerosol is charged and guided into a double cylinder composed of an outer cylinder and an inner cylinder. After sealing both ends, a voltage is applied to the outer cylinder to flow into the inner cylinder. The current is measured with a highly sensitive ammeter, and the change in the current value gives information corresponding to the electric mobility to obtain the electric mobility distribution, and the particle size distribution is measured based on this. A particle size distribution measuring apparatus has been proposed (see, for example, Patent Document 1).

また、図５に例示するＤＭＡとＣＮＣを組み合わせたものでは、エアロゾルは入口３１からインパクター３２で大きな粒子を取り除いた後、荷電部３３でガス中に浮遊している微小粒子を帯電する。この帯電した微小粒子を、入口３４から供給される清浄空気（シースエア）と共に、高電位が印加されている中央ロッド３５と、接地（アース）されている外筒３６との間の電位場を通過させ、特定の狭い範囲の電気移動度をもつ微小粒子のみをスリット３７に導いて分級する。この分級した微小粒子をＣＮＣ３８に導く。また、その他の粒子と空気やガスは出口３９より排出される。この中央ロッド３５と外筒３６との間の電位場を変化させることにより、分級する電気移動度の範囲を変更することができ、分級する粒子径の範囲を設定できる。   In the combination of DMA and CNC illustrated in FIG. 5, the aerosol removes large particles from the inlet 31 with the impactor 32 and then charges the fine particles suspended in the gas with the charging unit 33. The charged fine particles pass through a potential field between the central rod 35 to which a high potential is applied and the outer cylinder 36 that is grounded (grounded) together with clean air (sheath air) supplied from the inlet 34. Then, only fine particles having a specific narrow range of electric mobility are guided to the slit 37 and classified. The classified fine particles are guided to the CNC 38. Further, other particles, air and gas are discharged from the outlet 39. By changing the potential field between the central rod 35 and the outer cylinder 36, the range of the electric mobility to be classified can be changed, and the range of the particle diameter to be classified can be set.

しかしながら、ＤＭＡとＣＮＣの組み合わせた装置では、特定の粒径を中心とした狭い範囲の微小粒子のみを取り出して捕集し検出するため、同時に広範囲の微小粒子の捕集は不可能である。そのため、広範囲の分級のためにＤＭＡの電圧を走査する必要があり、高速な測定は難しく、測定に１分以上の時間が必要となるという問題がある。なお、高速化のために、複数電極とエレクトロメータを設置した装置もあるが、構造が複雑で高価である。   However, in a device combining DMA and CNC, only a small range of fine particles centered on a specific particle size is taken out and collected and detected, so that it is impossible to collect a wide range of fine particles at the same time. Therefore, it is necessary to scan the DMA voltage for a wide range of classification, and it is difficult to perform high-speed measurement, and there is a problem that a time of 1 minute or longer is required for the measurement. In addition, there is an apparatus in which a plurality of electrodes and an electrometer are installed for speeding up, but the structure is complicated and expensive.

更に、上記のような多段インパクターやＤＭＡとＣＮＣの組合せ装置を用いた場合には、所定の粒径範囲に存在する粒子数は、測定データを用いて積算処理する必要があり、解析の手間が煩雑であるという問題もある。   Further, when the multistage impactor as described above or a combination device of DMA and CNC is used, the number of particles existing in a predetermined particle size range needs to be integrated using measurement data, which is troublesome in analysis. There is also a problem that is complicated.

その上、ＤＭＡの粒子捕集電極に微小粒子を捕集するためには、この微小粒子をコロナ放電等で帯電させる必要があるが、微小粒子全部を荷電させることは難しく、微小粒子全数に対する荷電した微小粒子の割合を１００％にすることができないという問題がある。そのため、高精度の測定を行うためには、別試験によって得られた値を基に補正値を算出して、この補正値で粒子捕集電極に捕集された微小粒子の数を補正する必要がある。言い換えれば、粒径に依存する一定の荷電効率を仮定している。この場合には、この仮定による誤差が生じることになり、微小粒径ではその誤差が大きくなるという問題がある。   In addition, in order to collect the microparticles on the DMA particle collection electrode, it is necessary to charge the microparticles by corona discharge or the like. However, it is difficult to charge all the microparticles, and the total number of microparticles is charged. There is a problem that the proportion of the fine particles cannot be made 100%. Therefore, in order to perform high-accuracy measurement, it is necessary to calculate a correction value based on the value obtained by another test, and to correct the number of microparticles collected on the particle collection electrode with this correction value. There is. In other words, a constant charging efficiency depending on the particle size is assumed. In this case, an error due to this assumption occurs, and there is a problem that the error increases with a minute particle size.

一方、自動車搭載のエンジンを含めた内燃機関から排出される微小粒子は、一山あるいは二山の粒子数濃度粒径分布を示すことが知られている。一山の場合は集積モード粒子(accumulation モード粒子）と呼ばれる燃焼生成物のすす粒子（表面に付着した有機化合物を含め）が主である。また、図３に示すディーゼル排出微小粒子の粒径分布のように、二山の場合は集積モード粒子に加え、核モード粒子(nuclei モード粒子) が生成している。二種類のモード粒子は運転条件による粒径の変化は小さく、５０ｎｍ付近に境界が存在し、その境界の上下の粒径範囲に対応した粒子数が概略の集積モード粒子数と核モード粒子数となる。   On the other hand, it is known that fine particles discharged from internal combustion engines including engines mounted on automobiles show a particle number concentration particle size distribution of one mountain or two mountains. In the case of a mountain, soot particles (including organic compounds attached to the surface) of combustion products called accumulation mode particles (accumulation mode particles) are mainly used. Further, as in the particle size distribution of diesel exhaust microparticles shown in FIG. 3, in the case of two peaks, in addition to the accumulation mode particles, nuclear mode particles (nuclei mode particles) are generated. The two types of mode particles have small changes in particle size due to operating conditions, and there are boundaries near 50 nm. The number of particles corresponding to the particle size range above and below the boundary is approximately the number of accumulated mode particles and the number of nuclear mode particles. Become.

これらの各モード粒子は、それぞれの物理・化学的性状や大気中での動態や健康への影響度合等が異なり、その排出量は内燃機関の運転条件に応じて変動することが知られている。そのため、これらの２種の粒子の排出量の変動を測定することは、内燃機関の微小粒子排出の実態の把握とその大気・健康への影響を評価する上で重要な課題となっている。
特開平８−２６１９１１号公報 It is known that each of these mode particles has different physical and chemical properties, dynamics in the atmosphere, the degree of influence on health, etc., and their emissions vary depending on the operating conditions of the internal combustion engine. . Therefore, measuring fluctuations in the emissions of these two types of particles is an important issue in understanding the actual state of microparticle emissions from internal combustion engines and evaluating their impact on the atmosphere and health.
JP-A-8-261911

本発明は、上記の問題を解決するためになされたものであり、その目的は、自動車の排気ガス等に含まれる微小粒子の粒子数を、微分型電気移動度測定装置（ＤＭＡ）と高感度電流計と凝縮核計数器（ＣＮＣ）を利用して測定する微小粒子の粒子数計測方法及び装置において、粒子の荷電効率を実測値から算出して補正することにより、精度の高い測定をすることができる微小粒子の粒子数計測方法及び装置を提供することにある。   The present invention has been made in order to solve the above-described problems, and an object of the present invention is to determine the number of fine particles contained in an automobile exhaust gas or the like by using a differential electric mobility measuring device (DMA) and a high sensitivity. In a method and apparatus for measuring the number of fine particles using an ammeter and a condensation nucleus counter (CNC), the charge efficiency of the particles is calculated from the actual measurement value and corrected to make a highly accurate measurement. It is an object to provide a method and apparatus for measuring the number of fine particles.

また、更なる目的は、自動車搭載の内燃機関等の排出ガス中に含まれる核モード粒子と集積モード粒子を電圧等の走査をせずに、微分型電気移動度測定装置により分級し、これらのモード粒子の粒子数を直接測定ができる微小粒子の粒子数計測方法及び装置を提供することにある。   A further object is to classify the nuclear mode particles and the accumulated mode particles contained in the exhaust gas of an internal combustion engine mounted on an automobile by a differential electric mobility measuring device without scanning the voltage, etc. It is an object of the present invention to provide a method and apparatus for measuring the number of fine particles capable of directly measuring the number of mode particles.

上記の目的を達成するための本発明の微小粒子の粒径別捕集方法は、微小粒子を含んだ排出ガスを、荷電器により帯電させ、微分型電気移動度測定装置（ＤＭＡ：Differential Mobility Analyser) を用いて電気移動度により分級し、所定の範囲の粒径を有する粒子群を粒子捕集電極で捕集し、該粒子捕集電極に発生する電流を高感度電流計で検出し、該検出電流から前記粒子群の粒子数を検出すると共に、前記微分型電気移動度測定装置から排出される排気ガス中の少なくとも一部に含まれる粒子数を凝縮核計数器（ＣＮＣ：Condensation Nucleus Counter）で計数する微小粒子の粒子数計測方法であって、
前記微分型電気移動度測定装置の分級用の電極に所定の時間間隔で電圧を印加して、電圧印加時には、前記凝縮核計数器で前記微分型電気移動度測定装置で捕集されずに流出してきた粒子数を計数し、電圧非印加時には前記凝縮核計数器で排気ガス中の粒径の全範囲における粒子数を計数し、前記凝縮核計数器の電圧非印加時の粒子数と電圧印加時の粒子数との差から算出される粒子数と、前記高感度電流計で求めた電流値とを比較して、前記粒子群の粒子の荷電効率を算出し、該荷電効率を使用して、前記高感度電流計で求めた電流値から検出される粒子数を補正して、前記粒子群の粒子数を算出することを特徴とする。 In order to achieve the above object, the method for collecting fine particles according to the particle size of the present invention comprises charging a discharge gas containing fine particles with a charger, and a differential mobility analyzer (DMA). ) Is used to classify particles according to electric mobility, and a particle group having a particle size in a predetermined range is collected by a particle collecting electrode, and a current generated in the particle collecting electrode is detected by a highly sensitive ammeter, The number of particles of the particle group is detected from the detected current, and the number of particles contained in at least a part of the exhaust gas discharged from the differential electric mobility measuring device is a condensation nucleus counter (CNC). A method for measuring the number of fine particles counted in
A voltage is applied to the classification electrode of the differential type electric mobility measuring device at a predetermined time interval, and when the voltage is applied, the condensed nuclear counter flows out without being collected by the differential type electric mobility measuring device. When the voltage is not applied, the condensation nucleus counter counts the number of particles in the entire range of the particle size in the exhaust gas, and when the voltage of the condensation nucleus counter is not applied, the number of particles and voltage application Comparing the number of particles calculated from the difference between the number of particles at the time and the current value obtained with the high-sensitivity ammeter, the charge efficiency of the particles of the particle group is calculated, and the charge efficiency is used. The number of particles detected from the current value obtained by the high sensitivity ammeter is corrected to calculate the number of particles in the particle group.

これにより、自動車の排気ガス等に含まれる微小粒子の粒子数を、微分型電気移動度測定装置（ＤＭＡ）と高感度電流計と凝縮核計数器（ＣＮＣ）を利用して測定する微小粒子の粒子数計測方法において、粒子の荷電効率を実測値から算出して補正するので、精度の高い測定をすることができる。   As a result, the number of fine particles contained in automobile exhaust gas or the like is measured using a differential electric mobility measuring device (DMA), a high-sensitivity ammeter, and a condensation nucleus counter (CNC). In the particle number measuring method, the charge efficiency of particles is calculated and corrected from the actual measurement value, so that highly accurate measurement can be performed.

また、上記の目的を達成するための微小粒子の粒子数計測方法は、微小粒子を含んだ排出ガスを、荷電器により帯電させ、微分型電気移動度測定装置を用いて電気移動度により分級し、この分級の際に、第１の所定の範囲の粒径を有する第１の粒子群を、前記微分型電気移動度測定装置の粒子捕集電極で捕集し、該粒子捕集電極に発生する電流を高感度電流計で検出し、該検出電流から前記第１の粒子群の粒子数を検出すると共に、前記微分型電気移動度測定装置から排出される排気ガス中の少なくとも一部に含まれる粒子数を凝縮核計数器で計数する微小粒子の粒子数計測方法であって、
前記微分型電気移動度測定装置の電極において所定の時間間隔で電圧を印加して、電圧印加時に、前記凝縮核計数器で排気ガス中の前記第１の所定の範囲外の第２の所定の範囲の粒径を有する前記第２の粒子群の粒子数を計数し、電圧非印加時には前記凝縮核計数器で排気ガス中の粒径の全範囲における粒子数を計数し、前記凝縮核計数器の電圧非印加時の粒子数と、電圧印加時の粒子数との差から算出した粒子数と、前記高感度電流計で求めた電流値とを比較して、前記第１の粒子群の荷電効率を算出し、該荷電効率を使用して、前記高感度電流計で求めた電流値から検出される前記第１の粒子群の粒子数を補正して、前記第１の粒子群の粒子数を算出することを特徴とする。 In addition, in order to achieve the above object, the method for measuring the number of microparticles is to charge the exhaust gas containing the microparticles with a charger and classify the exhaust gas using a differential electric mobility measuring device. During the classification, the first particle group having a particle diameter in the first predetermined range is collected by the particle collecting electrode of the differential electric mobility measuring device and generated in the particle collecting electrode. Is detected by a highly sensitive ammeter, and the number of particles of the first particle group is detected from the detected current, and is included in at least a part of the exhaust gas discharged from the differential electric mobility measuring device A method for measuring the number of fine particles by counting the number of particles to be counted with a condensation nucleus counter,
A voltage is applied to the electrodes of the differential electric mobility measuring device at predetermined time intervals, and when the voltage is applied, the condensation nucleus counter uses a second predetermined predetermined value outside the first predetermined range in the exhaust gas when the voltage is applied. The number of particles of the second particle group having a particle size in a range is counted, and when no voltage is applied, the number of particles in the entire range of particle sizes in exhaust gas is counted by the condensation nucleus counter, and the condensation nucleus counter The number of particles calculated from the difference between the number of particles when no voltage is applied and the number of particles when a voltage is applied is compared with the current value obtained by the high-sensitivity ammeter to charge the first particle group. The efficiency is calculated, and the charge efficiency is used to correct the number of particles of the first particle group detected from the current value obtained by the high sensitivity ammeter, so that the number of particles of the first particle group is corrected. Is calculated.

これにより、第１の粒子群（核モード粒子）と第２の粒子群（集積モード粒子）の二種類の粒子数を同時かつ高速に測定できる。排出ガスに含まれた微小粒子は電気移動度により分級するので、コロナ放電を用いた荷電部により微小粒子を帯電させて、その後、高電圧を印加した二重円筒電極等のＤＭＡにより分級して、第１の粒子群は粒子捕集電極（外側電極）に捕集され、この粒子捕集電極に接続された高感度電流計（エレクトロメータ）により電流が検出される。一方、ＤＭＡを通り抜けた第２の粒子群は、ＤＭＡの末端部の混合部で絞られ、全体的に混合された後、一部がＣＮＣに分岐・検出され、計数される。この構成により、二種類のモード粒子の粒子数を同時かつリアルタイムに計測することができ、粒径分布測定装置と比べて安価、高速、簡便な計測が可能となる。   Thereby, the number of two types of particles, the first particle group (nuclear mode particle) and the second particle group (accumulated mode particle), can be measured simultaneously and at high speed. Since the microparticles contained in the exhaust gas are classified by the electric mobility, the microparticles are charged by a charged portion using corona discharge, and then classified by a DMA such as a double cylindrical electrode to which a high voltage is applied. The first particle group is collected by a particle collecting electrode (outer electrode), and a current is detected by a highly sensitive ammeter (electrometer) connected to the particle collecting electrode. On the other hand, the second particle group that has passed through the DMA is squeezed at the mixing portion at the end portion of the DMA, and after being mixed as a whole, a part is branched and detected by the CNC and counted. With this configuration, the number of particles of two types of mode particles can be measured simultaneously and in real time, and inexpensive, high-speed, and simple measurement can be performed as compared with a particle size distribution measuring apparatus.

そして、上記の目的を達成するための微小粒子の粒子数計測装置は、計測対象のガス中の微粒子を帯電させる荷電部と、ガス流に乗って移動する帯電微粒子を分級するための高電圧が印加される高電圧電極と、該高電圧電極と対向して配置され、所定の範囲の粒径を有する粒子群を捕集する粒子捕集用電極と、該粒子捕集用電極に接続されて帯電粒子が捕集されて発生する電流値を検出する高感度電流計と、前記高電圧電極と前記粒子捕集用電極の下流側に流出した排気ガス中の粒子数を測定するための凝縮核計数器とを有すると共に、
前記微分型電気移動度測定装置の分級用の電極に所定の時間間隔で電圧を印加して、電圧印加時には、前記凝縮核計数器で前記微分型電気移動度測定装置で捕集されずに流出してきた粒子数を計数し、電圧非印加時には前記凝縮核計数器で排気ガス中の粒径の全範囲における粒子数を計数し、前記凝縮核計数器の電圧非印加時の粒子数と電圧印加時の粒子数との差から算出される粒子数と、前記高感度電流計で求めた電流値とを比較して、前記粒子群の粒子の荷電効率を算出し、該荷電効率を使用して、前記高感度電流計で求めた電流値から検出される粒子数を補正して、前記粒子群の粒子数を算出する演算制御部とを有して構成される。 And the particle number measuring device for fine particles to achieve the above object has a charging unit for charging fine particles in a gas to be measured and a high voltage for classifying charged fine particles moving on the gas flow. A high-voltage electrode to be applied, a particle-collecting electrode disposed opposite to the high-voltage electrode and collecting a particle group having a particle size in a predetermined range; and connected to the particle-collecting electrode. A highly sensitive ammeter for detecting a current value generated by collecting charged particles, and a condensation nucleus for measuring the number of particles in exhaust gas flowing out downstream of the high voltage electrode and the particle collecting electrode And having a counter
A voltage is applied to the classification electrode of the differential type electric mobility measuring device at a predetermined time interval, and when the voltage is applied, the condensed nuclear counter flows out without being collected by the differential type electric mobility measuring device. When the voltage is not applied, the condensation nucleus counter counts the number of particles in the entire range of the particle size in the exhaust gas, and when the voltage of the condensation nucleus counter is not applied, the number of particles and voltage application Comparing the number of particles calculated from the difference between the number of particles at the time and the current value obtained with the high-sensitivity ammeter, the charge efficiency of the particles of the particle group is calculated, and the charge efficiency is used. And an arithmetic control unit that calculates the number of particles of the particle group by correcting the number of particles detected from the current value obtained by the high-sensitivity ammeter.

また、上記の目的を達成するための微小粒子の粒子数計測装置は、計測対象のガス中の微粒子を帯電させる荷電部と、ガス流に乗って移動する帯電微粒子を分級するための高電圧が印加される高電圧電極と、該高電圧電極と対向して配置され、第１の所定の範囲の粒径を有する第１の粒子群を捕集する粒子捕集用電極と、該粒子捕集用電極に接続されて帯電粒子が捕集されて発生する電流値を検出する高感度電流計と、前記高電圧電極と前記粒子捕集用電極の下流側に流出した排気ガス中の粒子数を測定するための凝縮核計数器とを有すると共に、
前記微分型電気移動度測定装置の電極において所定の時間間隔で電圧を印加して、電圧印加時には、前記凝縮核計数器で排気ガス中の前記第２の粒子群の粒子数を計数し、電圧非印加時には前記凝縮核計数器で排気ガス中の粒径の全範囲における粒子数を計数し、前記凝縮核計数器の電圧非印加時の粒子数と電圧印加時の粒子数との差から算出される粒子数と、前記高感度電流計で求めた電流値とを比較して、前記第１の粒子群の荷電効率を算出し、該荷電効率を使用して、前記高感度電流計で求めた電流値から検出される前記第１の粒子群の粒子数を補正して、前記第１の粒子群の粒子数を算出する演算制御部とを有して構成される。 In addition, the particle number measuring device for fine particles for achieving the above object has a charging unit for charging fine particles in a gas to be measured and a high voltage for classifying charged fine particles moving on the gas flow. A high-voltage electrode to be applied, a particle-collecting electrode disposed opposite to the high-voltage electrode and collecting a first particle group having a particle diameter in a first predetermined range, and the particle-collecting electrode A high-sensitive ammeter connected to the electrode for collecting charged particles and detecting a current value generated by collecting charged particles, and the number of particles in the exhaust gas flowing out downstream of the high-voltage electrode and the particle collecting electrode. Having a condensation nucleus counter for measuring,
A voltage is applied at predetermined time intervals at the electrodes of the differential electric mobility measuring device, and when the voltage is applied, the number of particles of the second particle group in the exhaust gas is counted by the condensation nucleus counter, When no voltage is applied, the condensation nucleus counter counts the number of particles in the entire range of particle sizes in the exhaust gas, and calculates from the difference between the number of particles when no voltage is applied to the condensation nucleus counter and the number of particles when voltage is applied. The charge efficiency of the first particle group is calculated by comparing the number of particles to be obtained and the current value obtained by the high sensitivity ammeter, and the charge efficiency is used to obtain the charge sensitivity of the first particle group. And a calculation control unit that corrects the number of particles of the first particle group detected from the current value and calculates the number of particles of the first particle group.

これらの微小粒子の粒子数計測装置によれば、上記の微小粒子の粒子数計測方法を実施でき、同様な作用効果を奏することができる。   According to the particle number measuring apparatus for these fine particles, the method for measuring the number of fine particles described above can be implemented, and the same effects can be achieved.

更に、上記の微小粒子の粒子数計測装置において、前記第１の粒子群を捕集する粒子捕集用電極とは別の電極を前記粒子捕集用電極の上流又は下流の少なくとも一方に設けて構成すると、この別の電極により、粒子捕集電極に捕集される粒径範囲を精度よく設定できる。また、この別の電極により、粒子捕集電極の高電圧による強電場が外部に漏れないようにすることができる。   Furthermore, in the particle count measuring apparatus for fine particles described above, an electrode different from the particle collecting electrode for collecting the first particle group is provided on at least one upstream or downstream of the particle collecting electrode. If constituted, the particle size range collected by the particle collection electrode can be set with high accuracy by this other electrode. In addition, this separate electrode can prevent a strong electric field due to the high voltage of the particle collecting electrode from leaking outside.

本発明の微小粒子の粒子数計測方法及び装置によれば、自動車の排気ガス等に含まれる微小粒子の粒子数を、微分型電気移動度測定装置（ＤＭＡ）と高感度電流計と凝縮核計数器（ＣＮＣ）を利用して測定する微小粒子の粒子数計測方法及び装置において、粒子の荷電効率を実測値から算出して補正することにより、精度の高い測定をすることができる。   According to the method and apparatus for measuring the number of microparticles according to the present invention, the number of microparticles contained in an automobile exhaust gas or the like is determined by using a differential electric mobility measuring device (DMA), a highly sensitive ammeter, and a condensation nucleus count. In the method and apparatus for measuring the number of fine particles measured using a container (CNC), it is possible to measure with high accuracy by calculating and correcting the charging efficiency of the particles from the actual measurement value.

更に、排出ガス中に含まれる二種類の粒子、核モード粒子と集積モード粒子を対象とすることにより、所定の設定をしたＤＭＡにより分級し、最小限（２台）の検出器を用いて２種類のモード粒子の粒子数を直接測定するので、ＤＭＡにおける電圧等の走査の必要がなく、瞬時に高速で測定することができる。また、測定結果については、粒径分布から積分して粒子数を算出する必要が無いので、演算の手間を省くことができる。その上、検出器が２つでも計測できるので、装置を安価に製造することできる。   Further, by targeting two types of particles contained in the exhaust gas, nuclear mode particles and accumulation mode particles, classification is performed by DMA having a predetermined setting, and 2 (minimum) detectors are used. Since the number of types of mode particles is directly measured, there is no need for scanning such as a voltage in DMA, and measurement can be performed instantaneously at high speed. Moreover, since it is not necessary to calculate the number of particles by integrating the measurement results from the particle size distribution, it is possible to save time and effort of calculation. Moreover, since even two detectors can be measured, the apparatus can be manufactured at low cost.

以下、本発明に係る実施の形態の微小粒子の粒子数計測方法及び装置について、図面を参照しながら説明する。図１に、この実施の形態の微小粒子の粒子数計測装置１の構成を示す。この微小粒子の粒子数計測装置１は、微分型電気移動度測定装置（ＤＭＡ：Differential Mobility Analyser：以下ＤＭＡ) ２、高感度電流計（エレクトロメータ）３、凝縮核計数器（ＣＮＣ：Condensation Nucleus Counter：以下ＣＮＣ）４、フィルタ５、ポンプ６、循環用配管７、及び、演算制御部８等を有して構成される。   Hereinafter, a method and an apparatus for measuring the number of fine particles according to an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the structure of the particle number measuring device 1 of the microparticles of this embodiment is shown. The particle number measuring device 1 for fine particles includes a differential mobility analyzer (DMA) 2, a highly sensitive ammeter (electrometer) 3, a condensation nucleus counter (CNC: Condensation Nucleus Counter). : CNC hereinafter) 4, filter 5, pump 6, circulation pipe 7, and calculation control unit 8 and the like.

ＤＭＡ２は、エアロゾル入口１１に連結する荷電器１２を一端側に有する円筒状体１３の内部に、中央電極（高電圧電極）１４と前方外側電極（別の電極）１５、粒子捕集電極１６、後方外側電極（別の電極）１７を有して構成される。また、筒状体１３の他端側には円錐台形状の混合部１８を有して構成される。この混合部１８は循環用配管７により、フィルタ５とポンプ６を経由して、筒状体１３の前方のエア入口１１ａに連結される。   The DMA 2 includes a central electrode (high voltage electrode) 14, a front outer electrode (another electrode) 15, a particle collecting electrode 16, a cylindrical body 13 having a charger 12 connected to the aerosol inlet 11 on one end side. A rear outer electrode (another electrode) 17 is provided. Further, the cylindrical body 13 has a frustoconical mixing portion 18 on the other end side. The mixing unit 18 is connected to the air inlet 11 a in front of the cylindrical body 13 by the circulation pipe 7 via the filter 5 and the pump 6.

中央電極１４は棒状に形成されると共に、円筒状体１３の中心部に配設され、電源１９により高電圧が印加される。一方、電極１５、１６、１７は、それぞれ円筒状に形成され前後方向に分かれて、中央電極１４を囲んで配置される。前方外側電極１５と後方外側電極１７は接地され、粒子捕集電極１６は高感度電流計３に接続される。なお、ＤＭＡ２の中央電極１４に印加する高電圧の値を設定する時には、後方外側電極１７を一時的に高感度電流計３に接続できるように構成する。この構成により、印加する高電圧の設定を、後方外側電極１７でに捕集されるに粒子群Ｍ３の粒子数が最小、即ち、後方外側電極１７に接続された高感度電流計３で検出される電流値が最小となるように電圧を調整することで、行うことができるようになる。   The center electrode 14 is formed in a rod shape and is disposed at the center of the cylindrical body 13, and a high voltage is applied by a power source 19. On the other hand, the electrodes 15, 16, and 17 are each formed in a cylindrical shape, divided in the front-rear direction, and disposed so as to surround the central electrode 14. The front outer electrode 15 and the rear outer electrode 17 are grounded, and the particle collecting electrode 16 is connected to the high sensitivity ammeter 3. When setting the value of the high voltage applied to the central electrode 14 of the DMA 2, the rear outer electrode 17 is temporarily connected to the high sensitivity ammeter 3. With this configuration, the setting of the high voltage to be applied is detected by the high-sensitive ammeter 3 connected to the rear outer electrode 17, that is, the number of particles in the particle group M 3 is minimized while being collected by the rear outer electrode 17. This can be done by adjusting the voltage so that the current value is minimized.

また、演算制御部８は、ＤＭＡ２の荷電器１２、電源１９、ポンプ６、高感度電流計３、ＣＮＣ４を制御すると共に、高感度電流計３やＣＮＣ４の出力値を入力する。この演算制御部８は、図２に示すように、所定の時間間隔でＤＭＡ２の高電圧電極１４に電圧を印加して、電圧印加時には、ＣＮＣ４で排気ガス中の第２の粒子群の粒子数Ｍ４を計数し、電圧非印加時にはＣＮＣで排気ガス中の粒径の全範囲における粒子数（Ｍ１〜Ｍ４）を計数する。このＣＮＣ４の電圧非印加時の粒子数Ｎｂと電圧印加時の粒子数Ｎａとの差から算出される粒子数Ｎｃ（＝Ｎｂ−Ｎａ）と、高感度電流計３で求めた電流値ｉｃとを比較して、第１の粒子群１の荷電効率ｆｃを算出し、この荷電効率ｆｃを使用して、高感度電流計３で求めた電流値ｉｍから検出される第１の粒子群Ｍ２の粒子数Ｎｍを補正して、第１の粒子群Ｍ２の粒子数Ｎｖを算出するように構成される。これにより、精度の高い測定をすることができるようになる。   The arithmetic control unit 8 controls the charger 12, the power source 19, the pump 6, the high sensitivity ammeter 3, and the CNC 4 of the DMA 2, and inputs the output values of the high sensitivity ammeter 3 and the CNC 4. As shown in FIG. 2, the arithmetic control unit 8 applies a voltage to the high voltage electrode 14 of the DMA 2 at a predetermined time interval, and when applying the voltage, the number of particles of the second particle group in the exhaust gas is detected by the CNC 4. M4 is counted, and when no voltage is applied, the number of particles (M1 to M4) in the entire range of the particle diameter in the exhaust gas is counted by the CNC. The particle number Nc (= Nb−Na) calculated from the difference between the particle number Nb when no voltage is applied to the CNC 4 and the particle number Na when the voltage is applied, and the current value ic obtained by the high sensitivity ammeter 3 In comparison, the charge efficiency fc of the first particle group 1 is calculated, and the particles of the first particle group M2 detected from the current value im obtained by the high sensitivity ammeter 3 using this charge efficiency fc. The number Nm is corrected to calculate the particle number Nv of the first particle group M2. Thereby, it becomes possible to perform highly accurate measurement.

次に、上記の構成の微小粒子の粒子数計測装置１の動作、及び、微小粒子の粒子数計測装置１による微小粒子の粒子数計測方法について説明する。   Next, the operation of the fine particle particle number measurement apparatus 1 having the above-described configuration and the fine particle particle number measurement method performed by the fine particle particle number measurement apparatus 1 will be described.

測定対象の微小粒子を含んだ排出ガスＡ１は、エアロゾル入口１１よりＤＭＡ２に取り入れられて荷電器１２に入り，コロナ放電等により微小粒子Ｍ１〜Ｍ４は帯電される。その後、ＤＭＡ２の円筒状体１３内へ導入され、ポンプ１０より送出されるシースエアＡ２によって、円筒状体１３内の層流に乗り、中央電極１４と、前方外側電極１５、粒子捕集電極１６、後方外側電極１７の間を通過する。   The exhaust gas A1 containing the microparticles to be measured is taken into the DMA 2 from the aerosol inlet 11, enters the charger 12, and the microparticles M1 to M4 are charged by corona discharge or the like. Thereafter, the sheath air A2 is introduced into the cylindrical body 13 of the DMA 2 and is sent from the pump 10 to ride on the laminar flow in the cylindrical body 13, and the central electrode 14, the front outer electrode 15, the particle collecting electrode 16, It passes between the rear outer electrodes 17.

微小粒子Ｍ１〜Ｍ４は中央電極１４と電極１５〜１７の間に印加された高電圧による電界中で電気移動度により分級される。核モード粒子Ｍ２より粒径が小さい微小粒子（図３のその他）Ｍ１は、前方外側電極１５に捕集され、粒径が所定の範囲（例えば５ｎｍ〜５０ｎｍ）の核モード粒子Ｍ２は、粒子捕集電極１６へ捕集される。また、核モード粒子Ｍ２と集積モードＭ４の間（図３の共存部）の粒径の微小粒子Ｍ３は、後方外側電極１７に捕集される。   The fine particles M1 to M4 are classified according to electric mobility in an electric field by a high voltage applied between the central electrode 14 and the electrodes 15 to 17. Microparticles M1 (others in FIG. 3) M1 having a smaller particle size than the nuclear mode particles M2 are collected by the front outer electrode 15, and the nuclear mode particles M2 having a particle size within a predetermined range (for example, 5 nm to 50 nm) are collected. It is collected by the collector electrode 16. Further, the fine particles M3 having a particle size between the nuclear mode particles M2 and the accumulation mode M4 (the coexisting portion in FIG. 3) are collected by the rear outer electrode 17.

最初に、中央電極１４と電極１５〜１７の間の電圧を設定する。この電圧は、後方外側電極１７に図３に示す共存部の粒子Ｍ３が捕集されるように設定される。つまり、高感度電流計３を後方外側電極１７に接続して、測定する粒子の粒径分布が図３に示すようなディーゼルエン粒子における典型的な粒径分布をしている際に、粒子数の谷間である共存部が後方外側電極１７の捕集範囲となるように電圧を調整する。言い換えれば、この後方外側電極１７に捕集されるに粒子群Ｍ３の粒子数が最小、即ち、検出される電流値が最小となるように電圧を調整する。この調整により電圧設定状態を最適とする。この設定により、各モードの粒子Ｍ１〜Ｍ３の大部分（９０％以上）の粒子をＤＭＡ２で捕集できるようになる。この電圧設定後は、高感度電流計３を粒子捕集電極１６に接続する。   First, a voltage between the center electrode 14 and the electrodes 15 to 17 is set. This voltage is set so that the particles M3 in the coexisting portion shown in FIG. That is, when the high-sensitivity ammeter 3 is connected to the rear outer electrode 17 and the particle size distribution of the particles to be measured has a typical particle size distribution in diesel ene particles as shown in FIG. The voltage is adjusted so that the coexistence part which is the valley of the region is within the collection range of the rear outer electrode 17. In other words, the voltage is adjusted so that the number of particles in the particle group M3 collected by the rear outer electrode 17 is minimum, that is, the detected current value is minimized. This adjustment optimizes the voltage setting state. By this setting, most of the particles M1 to M3 (90% or more) in each mode can be collected by DMA2. After this voltage setting, the high sensitivity ammeter 3 is connected to the particle collecting electrode 16.

この前方外側電極１５と後方外側電極１７により、粒子捕集電極１６に捕集される粒径範囲を精度よく設定でき、核モード粒子Ｍ２と集積モード粒子Ｍ４の間（共存部）の微粒子Ｍ３を分離することができる。また、この前方外側電極１５と後方外側電極１７は、ＤＭＡ２の中央電極１５と粒子捕集電極１６の間の高電圧で生じる強電場を外部に漏らさないという役割を果たしている。   By the front outer electrode 15 and the rear outer electrode 17, the particle size range collected by the particle collecting electrode 16 can be set with high accuracy, and the fine particles M3 between the nuclear mode particles M2 and the accumulated mode particles M4 (coexistence part) can be obtained. Can be separated. Further, the front outer electrode 15 and the rear outer electrode 17 serve to prevent a strong electric field generated by a high voltage between the central electrode 15 of the DMA 2 and the particle collecting electrode 16 from leaking outside.

次に、この設定された高電圧を印加した電圧印加の状態では、粒子捕集電極１６に核モード粒子Ｍ２が捕集されると、荷電器１２のコロナ放電等で帯電した核モード粒子Ｍ２の荷電が粒子捕集電極１６に放出される。この荷電の放出は、粒子捕集電極１６に接続された高感度電流計３により電流として検出されるので、その電流値により粒子数を算出する。   Next, in the state of voltage application where the set high voltage is applied, when the nuclear mode particle M2 is collected on the particle collecting electrode 16, the nuclear mode particle M2 charged by corona discharge or the like of the charger 12 is collected. Charge is emitted to the particle collecting electrode 16. Since the discharge of this charge is detected as a current by the high sensitivity ammeter 3 connected to the particle collecting electrode 16, the number of particles is calculated from the current value.

そして、粒径が大きいためにＤＭＡ２内の電極１５〜１７に捕集されなかった集積モード粒子Ｍ４は、その電気移動度に応じて同心円状に分級されて円筒状体１３の他端側に流出するが、ガス流を円錐状に絞ってガス流と共に流出してくる粒子を混合する混合部１８において、均一に混合される。この混合ガスＡ３の一部がＣＮＣ４に吸引されて、この混合ガスＡ３中の集積モード粒子Ｍ４が光学的に計数される。なお、この集積モード粒子Ｍ４のような粒径の大きな粒子は、荷電器１２において多重荷電される比率が高いために電流検出で正確な計数をすることが難しいので、ＣＮＣ４のような光学的検出を用いることが好ましい。   The accumulated mode particles M4 that are not collected by the electrodes 15 to 17 in the DMA 2 due to the large particle size are classified concentrically according to their electric mobility and flow out to the other end side of the cylindrical body 13. However, the gas flow is squeezed into a conical shape and mixed uniformly in the mixing unit 18 where the particles flowing out together with the gas flow are mixed. A part of the mixed gas A3 is sucked into the CNC 4, and the accumulation mode particles M4 in the mixed gas A3 are optically counted. Since particles having a large particle size such as the accumulation mode particle M4 have a high ratio of multiple charges in the charger 12, it is difficult to accurately count with current detection. Is preferably used.

一方、混合ガスＡ３の内、ＣＮＣ４により吸引されなかった残りの排ガスＡ４中の微小粒子はフィルタ５で除去される。このフィルタ５を通過したガスＡ５は、ポンプ６により、微小粒子を含まないシースエアＡ２として、エア入口１１ａに循環供給される。   On the other hand, among the mixed gas A3, fine particles in the remaining exhaust gas A4 that have not been sucked by the CNC 4 are removed by the filter 5. The gas A5 that has passed through the filter 5 is circulated and supplied to the air inlet 11a by the pump 6 as sheath air A2 that does not contain fine particles.

従って、電圧印加時は、排出ガス中の微小粒子Ｍ１〜Ｍ４の内、核モード粒子Ｍ２が高感度電流計３により電気的に検出・計測され、同時に、集積モード粒子Ｍ４がＣＮＣ４により光学的に検出・計数される。一方、中央電極１４に高電圧が印加されない電圧非印加時では、ＤＭＡ２は分級されないため、粒子径が全範囲に及ぶ粒子Ｍ１〜Ｍ４がＣＮＣ４により光学的に検出・計数される。   Therefore, when voltage is applied, among the fine particles M1 to M4 in the exhaust gas, the nuclear mode particle M2 is electrically detected and measured by the high sensitivity ammeter 3, and at the same time, the integrated mode particle M4 is optically detected by the CNC 4. Detected and counted. On the other hand, when no voltage is applied to the center electrode 14 and no voltage is applied, the DMA 2 is not classified, and thus the particles M 1 to M 4 whose particle diameters cover the entire range are optically detected and counted by the CNC 4.

次に、高感度電流計３により検出された粒子数の補正について説明する。この補正は、荷電部１２では、微小粒子全部を荷電させることは難しく、微小粒子全数に対する荷電した微小粒子の割合を１００％にすることができないので、この荷電効率ｆｃを測定し、この実測値で補正し、測定精度を向上させるものである。   Next, correction of the number of particles detected by the high sensitivity ammeter 3 will be described. In this correction, since it is difficult for the charging unit 12 to charge all the microparticles and the ratio of the charged microparticles to the total number of microparticles cannot be 100%, the charging efficiency fc is measured, and the actual measurement value is obtained. Correction is performed to improve measurement accuracy.

この荷電効率ｆｃの測定は、ＤＭＡ中央電極１４と、前方ＤＭＡ外側電極１５、ＤＭＡ粒子捕集電極１６、後方ＤＭＡ外側電極１７の間に、図２に示すように所定の時間間隔で電圧を印加して、電圧印加時（オン時）には、ＣＮＣ９で排気ガス中の集積モード粒子（図３の「ＣＮＣ検出分」）Ｍ４の粒子数Ｎａを計数し、電圧非印加時（オフ時）にはＣＮＣ９で排気ガス中の粒径の全範囲（図３の「その他」＋「ＤＭＡ捕集分」＋「共存部」＋「ＣＮＣ検出部」）における粒子数Ｎｂを計数する。なお、ＤＭＡ２の印加電圧を調整してより適切に設定すると、「その他」と「共存部」の粒子数を無視できるレベルにすることができるので、電圧非印加時のＳＮＣ９で検出される粒子数Ｎｂを、図３の「ＤＭＡ捕集分」＋「ＣＮＣ検出部」の粒子数、即ち、核モード粒子Ｍ２の粒子数と集積モード粒子Ｍ４の粒子数の和とみなすことができるようになる。   The charge efficiency fc is measured by applying a voltage between the DMA central electrode 14, the front DMA outer electrode 15, the DMA particle collecting electrode 16, and the rear DMA outer electrode 17 at predetermined time intervals as shown in FIG. When the voltage is applied (ON), the CNC 9 counts the number Na of accumulated mode particles M4 in the exhaust gas ("CNC detection" in FIG. 3) M4, and when no voltage is applied (OFF). CNC 9 counts the number Nb of particles in the entire range of particle sizes in the exhaust gas (“others” + “DMA trapped portion” + “coexistence portion” + “CNC detection portion” in FIG. 3). If the applied voltage of DMA2 is adjusted and set more appropriately, the number of particles of “others” and “coexistence part” can be neglected, so the number of particles detected by SNC 9 when no voltage is applied. Nb can be regarded as the number of particles of “DMA collection” + “CNC detection unit” in FIG. 3, that is, the sum of the number of nuclear mode particles M2 and the number of accumulation mode particles M4.

この粒径の全範囲における粒子数Ｎｂと、集積モード粒子Ｍ４の粒子数Ｎａとの差から算出した粒子数Ｎｃ（＝Ｎｂ−Ｎａ）と、高感度電流計３で求めた電流値ｉｃとを比較して、ＤＭＡ２で捕集された粒子群の荷電効率ｆｃを算出する。一般的に荷電効率ｆは、電流値ｉと粒子数ｎと電気素量ｅとの間に「ｉ＝ｆ×ｅ×Ｎ」の関係があるので、ＤＭＡ２で捕集された粒子群の荷電効率ｆｃは「ｆｃ＝ｉｃ／（ｅ×Ｎｃ）＝ｉｃ／（ｅ×（Ｎｂ−Ｎａ）」となる。これにより荷電効率ｆｃを求めることができる。この荷電効率ｆｃを用いて、計測時に得られる高感度電流計３で求めた電流値ｉｍから算出される粒子数Ｎｍを補正して、粒子数Ｎｖを算出する（Ｎｖ＝Ｎｍ／ｆｃ）。   The particle number Nb (= Nb−Na) calculated from the difference between the particle number Nb in the entire range of the particle diameter, the particle number Na of the accumulation mode particles M4, and the current value ic obtained by the high sensitivity ammeter 3 In comparison, the charging efficiency fc of the particle group collected by DMA2 is calculated. In general, the charge efficiency f has a relationship of “i = f × e × N” among the current value i, the number of particles n, and the elementary charge e, so that the charge efficiency of the particle group collected by the DMA 2 fc becomes “fc = ic / (e × Nc) = ic / (e × (Nb−Na).” Thus, the charging efficiency fc can be obtained, which is obtained at the time of measurement using the charging efficiency fc. The particle number Nm calculated from the current value im obtained by the high sensitivity ammeter 3 is corrected to calculate the particle number Nv (Nv = Nm / fc).

なお、この電圧印加と電圧非印加の時間間隔は、排気ガスの変動度合や要求される測定精度に応じて決まり、予め実験等により求めて設定しておくことができる。この時間間隔は周期的に設定してもよいが、排気ガスの変動度合やエンジンの排気ガスの場合にはエンジンの運転状態の変化に応じて、自動的に、電圧印加と電圧非印加の補正用制御を設けるように演算制御部８を構成してもよい。   The time interval between the voltage application and the voltage non-application is determined according to the degree of fluctuation of exhaust gas and the required measurement accuracy, and can be obtained and set in advance by experiments or the like. This time interval may be set periodically, but in the case of exhaust gas fluctuations or engine exhaust gas, the correction of voltage application and voltage non-application is automatically performed according to changes in engine operating conditions. The arithmetic control unit 8 may be configured so as to provide control for operation.

この微小粒子の粒子数計測方法及び装置１は、ＣＮＣ４で光学的に粒子数を検出し、更に、ＤＭＡ２の高感度電流計３により電流値ｉｍを計測することにより、ＤＭＡ２の電圧非印加時の粒子数Ｎｂと電圧印加時の粒子数Ｎａとの差から求められるＤＭＡ２で捕集される粒子数Ｎｃ（＝Ｎｂ−Ｎａ）を求め、この粒子数Ｎｃと電流値ｉｃの比から荷電効率ｆｃを実測値から算出することができるので、測定精度を向上させることができる。   This method and apparatus 1 for measuring the number of particles of fine particles optically detects the number of particles with the CNC 4 and further measures the current value im with the high-sensitive ammeter 3 of the DMA 2 so that the DMA 2 voltage is not applied. The number of particles Nc (= Nb−Na) collected by DMA2 obtained from the difference between the number of particles Nb and the number of particles Na when voltage is applied is obtained, and the charging efficiency fc is calculated from the ratio of the number of particles Nc and the current value ic. Since it can be calculated from the actual measurement value, the measurement accuracy can be improved.

更に、排出ガスＡ１中に含まれる二種類の粒子、核モード粒子Ｍ２と集積モード粒子Ｍ４を所定の設定のＤＭＡ２により分級して、２台の検出器３、４で粒子数を検出するので、電圧等の走査の必要がなく瞬時に高速で測定を行うことができる。また、測定結果に関しては、核モード粒子Ｍ２と集積モード粒子Ｍ４の粒子数が直接得られるので、粒径分布から積分して粒子数を算出する必要が無くなる。   Furthermore, since the two types of particles contained in the exhaust gas A1, the nuclear mode particles M2 and the accumulation mode particles M4 are classified by a predetermined setting DMA2, and the number of particles is detected by the two detectors 3 and 4, Measurements can be performed instantaneously and at high speed without the need for voltage scanning. Further, regarding the measurement result, the number of particles of the nuclear mode particles M2 and the accumulation mode particles M4 can be directly obtained, so that it is not necessary to calculate the number of particles by integrating from the particle size distribution.

本発明に係る実施の形態の微小粒子の粒子数計測装置の構成を示す図である。It is a figure which shows the structure of the particle number measuring apparatus of the microparticles | fine-particles of embodiment which concerns on this invention. ＤＭＡの電圧印加と電圧非印加の状態を示す図である。It is a figure which shows the state of voltage application and voltage non-application of DMA. ディーゼル排出微小粒子（ＤＥＰ）の粒径分布の一例を示す図である。It is a figure which shows an example of the particle size distribution of diesel exhaust microparticles (DEP). 多段インパクターの構成の一例を示す図である。It is a figure which shows an example of a structure of a multistage impactor. ＤＭＡとＣＮＣの組合せ装置の構成の一例を示す図である。It is a figure which shows an example of a structure of the combination apparatus of DMA and CNC.

符号の説明Explanation of symbols

１ 微小粒子の粒子数計測装置
２ 微分型電気移動度測定装置（ＤＭＡ）
３ 高感度電流計（エレクトロメータ）
４ 凝縮核計数器（ＣＮＣ）
８ 演算制御部
１２ 荷電器
１４ 中央電極
１５ 前方外側電極
１６ 粒子捕集電極
１７ 後方外側電極
１８ 混合部
１９ 電源 1 Fine particle number measuring device 2 Differential electric mobility measuring device (DMA)
3 High sensitivity ammeter (electrometer)
4 Condensation nucleus counter (CNC)
8 Arithmetic Control Unit 12 Charger 14 Center Electrode 15 Front Outer Electrode 16 Particle Collection Electrode 17 Rear Outer Electrode 18 Mixing Unit 19 Power Supply

Claims (5)

微小粒子を含んだ排出ガスを、荷電器により帯電させ、微分型電気移動度測定装置を用いて電気移動度により分級し、所定の範囲の粒径を有する粒子群を粒子捕集電極で捕集し、該粒子捕集電極に発生する電流を高感度電流計で検出し、該検出電流から前記粒子群の粒子数を検出すると共に、前記微分型電気移動度測定装置から排出される排気ガス中の少なくとも一部に含まれる粒子数を凝縮核計数器で計数する微小粒子の粒子数計測方法であって、
前記微分型電気移動度測定装置の分級用の電極に所定の時間間隔で電圧を印加して、電圧印加時には、前記凝縮核計数器で前記微分型電気移動度測定装置で捕集されずに流出してきた粒子数を計数し、電圧非印加時には前記凝縮核計数器で排気ガス中の粒径の全範囲における粒子数を計数し、前記凝縮核計数器の電圧非印加時の粒子数と電圧印加時の粒子数との差から算出される粒子数と、前記高感度電流計で求めた電流値とを比較して、前記粒子群の粒子の荷電効率を算出し、該荷電効率を使用して、前記高感度電流計で求めた電流値から検出される粒子数を補正して、前記粒子群の粒子数を算出することを特徴とする微小粒子の粒子数計測方法。 Exhaust gas containing fine particles is charged by a charger, classified by electric mobility using a differential electric mobility measuring device, and particles having a particle size in a predetermined range are collected by a particle collecting electrode And detecting the current generated in the particle collecting electrode with a highly sensitive ammeter, detecting the number of particles of the particle group from the detected current, and in the exhaust gas discharged from the differential electric mobility measuring device A method for measuring the number of fine particles by counting the number of particles contained in at least a part of the particle with a condensation nucleus counter,
A voltage is applied to the classification electrode of the differential type electric mobility measuring device at a predetermined time interval, and when the voltage is applied, the condensed nuclear counter flows out without being collected by the differential type electric mobility measuring device. When the voltage is not applied, the condensation nucleus counter counts the number of particles in the entire range of the particle size in the exhaust gas, and when the voltage of the condensation nucleus counter is not applied, the number of particles and voltage application Comparing the number of particles calculated from the difference between the number of particles at the time and the current value obtained with the high-sensitivity ammeter, the charge efficiency of the particles of the particle group is calculated, and the charge efficiency is used. A method for measuring the number of fine particles by correcting the number of particles detected from the current value obtained by the high sensitivity ammeter and calculating the number of particles in the particle group. 微小粒子を含んだ排出ガスを、荷電器により帯電させ、微分型電気移動度測定装置を用いて電気移動度により分級し、この分級の際に、第１の所定の範囲の粒径を有する第１の粒子群を、前記微分型電気移動度測定装置の粒子捕集電極で捕集し、該粒子捕集電極に発生する電流を高感度電流計で検出し、該検出電流から前記第１の粒子群の粒子数を検出すると共に、前記微分型電気移動度測定装置から排出される排気ガス中の少なくとも一部に含まれる粒子数を凝縮核計数器で計数する微小粒子の粒子数計測方法であって、
前記微分型電気移動度測定装置の電極において所定の時間間隔で電圧を印加して、電圧印加時に、前記凝縮核計数器で排気ガス中の前記第１の所定の範囲外の第２の所定の範囲の粒径を有する前記第２の粒子群の粒子数を計数し、電圧非印加時には前記凝縮核計数器で排気ガス中の粒径の全範囲における粒子数を計数し、前記凝縮核計数器の電圧非印加時の粒子数と、電圧印加時の粒子数との差から算出した粒子数と、前記高感度電流計で求めた電流値とを比較して、前記第１の粒子群の荷電効率を算出し、該荷電効率を使用して、前記高感度電流計で求めた電流値から検出される前記第１の粒子群の粒子数を補正して、前記第１の粒子群の粒子数を算出することを特徴とする微小粒子の粒子数計測方法。 The exhaust gas containing fine particles is charged by a charger, and classified by electric mobility using a differential type electric mobility measuring device, and at the time of classification, a first particle having a particle diameter in a first predetermined range is classified. 1 particle group is collected by a particle collecting electrode of the differential electric mobility measuring device, a current generated in the particle collecting electrode is detected by a highly sensitive ammeter, and the first current is detected from the detected current. A method for detecting the number of particles in a particle group and counting the number of particles contained in at least a part of exhaust gas discharged from the differential electric mobility measuring device with a condensation nucleus counter. There,
A voltage is applied to the electrodes of the differential electric mobility measuring device at predetermined time intervals, and when the voltage is applied, the condensation nucleus counter uses a second predetermined predetermined value outside the first predetermined range in the exhaust gas when the voltage is applied. The number of particles of the second particle group having a particle size in a range is counted, and when no voltage is applied, the number of particles in the entire range of particle sizes in exhaust gas is counted by the condensation nucleus counter, and the condensation nucleus counter The number of particles calculated from the difference between the number of particles when no voltage is applied and the number of particles when a voltage is applied is compared with the current value obtained by the high-sensitivity ammeter to charge the first particle group. The efficiency is calculated, and the charge efficiency is used to correct the number of particles of the first particle group detected from the current value obtained by the high sensitivity ammeter, so that the number of particles of the first particle group is corrected. A method for measuring the number of fine particles. 計測対象のガス中の微粒子を帯電させる荷電部と、ガス流に乗って移動する帯電微粒子を分級するための高電圧が印加される高電圧電極と、該高電圧電極と対向して配置され、所定の範囲の粒径を有する粒子群を捕集する粒子捕集用電極と、該粒子捕集用電極に接続されて帯電粒子が捕集されて発生する電流値を検出する高感度電流計と、前記高電圧電極と前記粒子捕集用電極の下流側に流出した排気ガス中の粒子数を測定するための凝縮核計数器とを有すると共に、
前記微分型電気移動度測定装置の分級用の電極に所定の時間間隔で電圧を印加して、電圧印加時には、前記凝縮核計数器で前記微分型電気移動度測定装置で捕集されずに流出してきた粒子数を計数し、電圧非印加時には前記凝縮核計数器で排気ガス中の粒径の全範囲における粒子数を計数し、前記凝縮核計数器の電圧非印加時の粒子数と電圧印加時の粒子数との差から算出される粒子数と、前記高感度電流計で求めた電流値とを比較して、前記粒子群の粒子の荷電効率を算出し、該荷電効率を使用して、前記高感度電流計で求めた電流値から検出される粒子数を補正して、前記粒子群の粒子数を算出する演算制御部とを有した微小粒子の粒子数計測装置。 A charging unit for charging fine particles in a gas to be measured, a high voltage electrode to which a high voltage for classifying charged fine particles moving on the gas flow is applied, and the high voltage electrode, A particle collecting electrode for collecting a particle group having a particle size in a predetermined range, and a high sensitivity ammeter connected to the particle collecting electrode to detect a current value generated by collecting charged particles; A condensation nucleus counter for measuring the number of particles in the exhaust gas flowing out downstream of the high voltage electrode and the particle collecting electrode,
A voltage is applied to the classification electrode of the differential type electric mobility measuring device at a predetermined time interval, and when the voltage is applied, the condensed nuclear counter flows out without being collected by the differential type electric mobility measuring device. When the voltage is not applied, the condensation nucleus counter counts the number of particles in the entire range of the particle size in the exhaust gas, and when the voltage of the condensation nucleus counter is not applied, the number of particles and voltage application Comparing the number of particles calculated from the difference between the number of particles at the time and the current value obtained with the high-sensitivity ammeter, the charge efficiency of the particles of the particle group is calculated, and the charge efficiency is used. An apparatus for measuring the number of particles of fine particles, comprising: an arithmetic control unit that corrects the number of particles detected from the current value obtained by the high-sensitivity ammeter and calculates the number of particles of the particle group. 計測対象のガス中の微粒子を帯電させる荷電部と、ガス流に乗って移動する帯電微粒子を分級するための高電圧が印加される高電圧電極と、該高電圧電極と対向して配置され、第１の所定の範囲の粒径を有する第１の粒子群を捕集する粒子捕集用電極と、該粒子捕集用電極に接続されて帯電粒子が捕集されて発生する電流値を検出する高感度電流計と、前記高電圧電極と前記粒子捕集用電極の下流側に流出した排気ガス中の粒子数を測定するための凝縮核計数器とを有すると共に、
前記微分型電気移動度測定装置の電極において所定の時間間隔で電圧を印加して、電圧印加時には、前記凝縮核計数器で排気ガス中の前記第２の粒子群の粒子数を計数し、電圧非印加時には前記凝縮核計数器で排気ガス中の粒径の全範囲における粒子数を計数し、前記凝縮核計数器の電圧非印加時の粒子数と電圧印加時の粒子数との差から算出される粒子数と、前記高感度電流計で求めた電流値とを比較して、前記第１の粒子群の荷電効率を算出し、該荷電効率を使用して、前記高感度電流計で求めた電流値から検出される前記第１の粒子群の粒子数を補正して、前記第１の粒子群の粒子数を算出する演算制御部とを有した微小粒子の粒子数計測装置。 A charging unit for charging fine particles in a gas to be measured, a high voltage electrode to which a high voltage for classifying charged fine particles moving on the gas flow is applied, and the high voltage electrode, A particle collecting electrode for collecting a first particle group having a particle size in a first predetermined range, and a current value generated by collecting charged particles connected to the particle collecting electrode are detected. A high-sensitivity ammeter, a condensation nucleus counter for measuring the number of particles in the exhaust gas flowing out downstream of the high-voltage electrode and the particle collection electrode,
A voltage is applied at predetermined time intervals at the electrodes of the differential electric mobility measuring device, and when the voltage is applied, the number of particles of the second particle group in the exhaust gas is counted by the condensation nucleus counter, When no voltage is applied, the condensation nucleus counter counts the number of particles in the entire range of particle sizes in the exhaust gas, and calculates from the difference between the number of particles when no voltage is applied to the condensation nucleus counter and the number of particles when voltage is applied. The charge efficiency of the first particle group is calculated by comparing the number of particles to be obtained and the current value obtained by the high sensitivity ammeter, and the charge efficiency is used to obtain the charge sensitivity of the first particle group. An apparatus for measuring the number of fine particles, comprising: an arithmetic control unit that corrects the number of particles of the first particle group detected from the measured current value and calculates the number of particles of the first particle group. 前記第１の粒子群を捕集する粒子捕集用電極とは別の電極を前記粒子捕集用電極の上流又は下流の少なくとも一方に設けたことを特徴とする請求項４記載の微小粒子の粒子数計測装置。   5. The microparticle according to claim 4, wherein an electrode different from the electrode for collecting particles that collects the first particle group is provided on at least one of the upstream and downstream sides of the electrode for collecting particles. Particle number measuring device.
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