JP2004257954A

JP2004257954A - Evaluation method for pressure loss of honeycomb structure and evaluation device therefor

Info

Publication number: JP2004257954A
Application number: JP2003051044A
Authority: JP
Inventors: Toshitaka Ishizawa; 俊崇石澤; Naoki Sugio; 直樹杉尾; Hideki Takeshima; 秀樹竹島; Kenichiro Sekiguchi; 謙一郎関口
Original assignee: Hitachi Metals Ltd
Current assignee: Proterial Ltd
Priority date: 2003-02-27
Filing date: 2003-02-27
Publication date: 2004-09-16
Anticipated expiration: 2023-02-27
Also published as: JP4026136B2

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an evaluation method and an evaluation device which can measure highly precisely a delicate difference between pressure losses made small when the pressure losses are further made smaller by setting the porosity of the partition wall of a honeycomb structure at 50% or more and a mean pore diameter thereof at 15 μm or more. <P>SOLUTION: By continuously supplying gas to the honeycomb structure with a determined allowable range to the flow rate of the gas, the pressure loss of the honeycomb structure is determined from the differential pressure between the inflow and outflow sides of the honeycomb structure which is measured when the flow rate of the gas is within the allowable range in a predetermined time. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】本発明は、排気ガスを浄化するのに使用されるハニカム構造体の圧力損失の評価方法および評価装置に関する。
【０００２】
【従来の技術】
ディーゼルエンジンやガソリンエンジンなど内燃機関の排ガスを浄化するのに使用される排ガス浄化用ハニカム構造体は、一般にセラミックあるいは金属などの耐熱材料で構成されており，内燃機関の排気系に組みこまれ、排ガス中に含まれる有害物質を取り除く役割を果たす。前記排ガス浄化用ハニカム構造体には、触媒物質を担持することにより目的の有害物質を取り除く役割を果たすものや、主にディーゼルエンジンの排ガス中の粒子状物質（ＰａｒｔｉｃｕｌａｔｅＭａｔｔｅｒｓ、以下「ＰＭ」という）を前記ハニカム構造体がろ過捕捉し、排ガス浄化に寄与するディーゼルパティキュレートフィルタ（以下ＤＰＦという）用ハニカム構造体もある。
【０００３】
前記排ガス浄化用ハニカム構造体は、その圧力損失により排ガスの流れを妨げるためエンジン出力の低下の原因となる。また、前記ＤＰＦ用ハニカム構造体においては、排ガス中のＰＭが前記ＤＰＦ用ハニカム構造体内部に捕捉され蓄積されるのに伴い、圧力損失が高くなりエンジン出力の低下につながる。このためハニカム構造体の初期の圧力損失や、ＰＭの蓄積後の圧力損失を把握する必要がある。
【０００４】
さて、ハニカム構造体の「圧力損失」とは、ハニカム構造体を気体が通過したときのハニカム構造体の上流側の気体の圧力値から下流側の気体の圧力値を引いたものであり、排気ガスがハニカム構造体を通過する際に受ける抵抗が最大の要因となる。従って、ハニカム構造体の隔壁の材料、厚さ、気孔率、細孔径など、また排気ガスが流入するハニカム構造体の入口端部形状などを、適切にする必要がある。
【０００５】
ハニカム構造体の圧力損失を求めて、評価する手段としては、日本工業規格（ＪＩＳ）の自動車用エアクリーナの試験方法を用いることがある（例えば、非特許文献１参照）。この非特許文献１の試験装置は、供試体（ＪＩＳでは自動車用エアクリーナ）を収納する試験用チャンバと、試験用チャンバの出口側および入口側に接続した差圧計と、出口側から順に送気管を介して接続したアブソリュートフィルタ、空気流量計、空気流量制御装置、および排気送風機などからなる。
そして、非特許文献１の試験装置で、供試体となるハニカム構造体の圧力損失を求める場合には、試験室の空気を１５分間以上流し、その後、差圧計により圧力損失を求めることになる。また、空気量、差圧などの値を、２０℃、相対湿度６５％、気圧１０１３ｈＰａの標準状態に補正して、圧力損失を求めることになる。また、例えば特許文献１に記載の発明のように前記ハニカム構造体を内燃機関の排気系に組み込み、求めた圧力損失をエンジンの排気流量で補正する方法や、特許文献２に記載の発明のように内燃機関を用いずに粒子含有気体発生器により前記ハニカム構造体に粒子を含有した気体を送り込み、前記ハニカム構造体の気体流入側と流出側との差圧より圧力損失を求める記載が見られる。これらはいずれも圧力損失の上昇後に測定を行うため、比較的容易に圧力損失が求められる。
【０００６】
ところで、前記ＤＰＦ用ハニカム構造体においては、一定量のＰＭが蓄積されるとこれを電気ヒータで燃焼させたり、逆洗エアーで除去しＤＰＦの再生を行う必要があるが、従来の電気ヒータで微粒子を燃焼再生する方法では、微粒子の自己発熱によりＤＰＦ用ハニカム構造体自体が溶損したり、また逆洗エアーを用いる場合は装置が複雑になる問題があり、最近では触媒物質の作用によりＤＰＦ用ハニカム構造体内で微粒子を連続的に燃焼させる技術（ＣＲＴシステム）が採用されるようになってきた。
【０００７】
【非特許文献１】
ＪＩＳＤ１６１２−１９８９自動車用エアクリーナの試験方法［第４頁第８．項（通気抵抗試験）、第２０頁第２．（１５）項（通気抵抗）、第２４頁（試験用ダスト）、第２７頁（図６パネル形フィルタエレメント用清浄効率及びダスト保持量試験装置）、第３２〜３４頁（標準状態に対する空気量及び通気抵抗の補正）］
【特許文献１】
特開平８−１０９８１８号公報
【特許文献２】
特許第２８０７３７０号公報
【０００８】
【発明が解決しようとする課題】
前記ＣＲＴシステムでは、定常状態においてＰＭは連続的に燃焼除去され蓄積されないので、ＰＭ蓄積による圧力損失の上昇はほとんどない。さらにＣＲＴシステムではＤＰＦ用ハニカム構造体の上流側に酸化触媒を担持したハニカム構造体の配置が不可欠である。場合によってはＤＰＦ用ハニカム構造体の下流側にＮＯｘ除去の触媒を担持したハニカム構造体の配置が必要になる事もあり、内燃機関の排気系全体の圧力損失が大きくなりエンジン出力の低下につながるので、ＤＰＦ用ハニカム構造体自体にも気孔率が５０％以上で平均細孔径１５μｍ以上の材料を用いたりセル構造を最適化する技術が適用される等、ＤＰＦ用ハニカム構造体そのものの圧力損失を低く抑えるための技術開発が進められており、その評価および検査を行うために低い圧力損失を精度良く求める必要がある。
【０００９】
ところがこのようなＤＰＦ用ハニカム構造体に前記自動車用エアクリーナの試験方法を用いて圧力損失を求めても、あるいは前記特許文献記載の圧力損失を求める方法を用いても、圧力損失自体が極めて小さい事から、ＤＰＦ用ハニカム構造体を流れる気体の流量および温度および湿度と測定環境の大気圧および温度および湿度のわずかな変化の影響が、圧力損失の値に大きくばらつきとして表れ、圧力損失を精度良く求めることは困難である。特に気体流量の変化については、流量制御弁のような流量を安定させる装置を用いてもなお存在する微小な流量の変化が、圧力損失の値に及ぼす影響は無視できない。したがって異なるハニカム構造体間の圧力損失のが異なると思われてもその差異が出ず、圧力損失を高精度に求めることができない。
【００１０】
したがって本発明の課題は、ハニカム構造体の圧力損失を高精度に求めることができる、ハニカム構造体の圧力損失の評価方法および評価装置を得ることにある。特に、ハニカム構造体の隔壁の気孔率を５０％以上、平均細孔径を１５μｍ以上などとして圧力損失をさらに小さくした場合での、小さくした圧力損失の微妙な違いを高精度に求めることができる、ハニカム構造体の圧力損失の評価方法および評価装置を得ることにある。
【００１１】
【課題を解決するための手段】
本発明者らは、上記課題について鋭意研究した。その結果、ハニカム構造体に供給する気体の流量の変化が少なく、安定した流れを保ったときの差圧を測定すれば、ハニカム構造体の圧力損失を高精度に求めることができるとの知見を得、本発明に想到した。
【００１２】
すなわち、本発明のハニカム構造体の圧力損失の評価方法は、ハニカム構造体に、気体の流量に対する許容範囲を決めて気体を連続して供給し、前記気体の流量が所定時間内で許容範囲にあるときに測定した前記ハニカム構造体の気体流入側と流出側との差圧から、前記ハニカム構造体の圧力損失を求めることを特徴とする。
これにより、前記気体の流量変化が小さく安定した流れを保った状態でハニカム構造体の気体流入側と流出側との差圧を測定することにより、ハニカム構造体の圧力損失を高精度に評価することができ、特に、ハニカム構造体の隔壁の気孔率を５０％以上、平均細孔径を１５μｍ以上などとして圧力損失をさらに小さくした場合での、小さくした圧力損失の微妙な違いをさらに高精度に評価することができる。
【００１３】
ここで、気体の流量が許容範囲にあるとは、例えば、３０Ｎｍ^３／ｍｉｎを中心に、許容範囲が±０．９Ｎｍ^３／ｍｉｎにあることを言う。また差圧の測定は、前記気体の流量が所定時間内で許容範囲にあるときに測定するのみではなく、連続的に測定しておき、前記気体の流量が所定時間内で許容範囲にあるときの差圧のみを抽出して圧力損失を求めることもできることは言うまでもない。
【００１４】
また、本発明のハニカム構造体の圧力損失の評価方法は、ハニカム構造体に、気体の流量に対する許容範囲を決めて前記気体を連続して供給し、前記気体の流量が所定時間内で許容範囲にあるときに、前記ハニカム構造体の気体流入側と流出側との差圧を測定し、次いで、前記差圧の測定後に連続する所定時間内で前記気体の流量が前記許容範囲にあるときに、前記差圧から圧力損失を求める方法を取ることもできる。これにより、前記気体の流量変化が小さく安定した流れを保った状態で、ハニカム構造体の気体流入側と流出側との差圧を測定し、かつ前記差圧の測定の後の前記気体の流量変化が小さいことを確認することにより、ハニカム構造体の圧力損失をより高精度に評価することができ、特に、ハニカム構造体の隔壁の気孔率を５０％以上、平均細孔径を１５μｍ以上などとして圧力損失をさらに小さくした場合での、小さくした圧力損失の微妙な違いを高精度に評価することができる。
ここで、ある経過した所定時間内とは例えば１０ｓ（秒）間、差圧の測定後に連続する所定時間内とは前記１０ｓに続く例えば３ｓ間を言う。
【００１５】
また、本発明のハニカム構造体の圧力損失の評価方法は、ハニカム構造体に、気体の流量に対する許容範囲を決めて前記気体を連続して供給し、前記気体の流量が所定時間内で第１の許容範囲で、前記気体の流量の平均が前記所定時間内で前記第１の許容範囲と中心を同じくして前記第１の許容範囲の広くとも２／３の幅を持った範囲内にあり、かつ前記所定時間内の直近短時間の前記気体の流量が前記第１の許容範囲より狭い第２の許容範囲で、前記直近短時間での前記気体の流量の平均が前記第２の許容範囲と中心を同じくして前記第２の許容範囲の広くとも２／３の幅を持った範囲内にあるときに、前記ハニカム構造体の気体流入側と流出側との差圧を測定し、次いで、前記差圧の測定後に連続する所定時間内で前記気体流量が前記第２の許容範囲にあるときに、前記差圧から圧力損失を求める方法を取ることもできる。ここで前記気体の流量の平均は、前記第１および第２の許容範囲と中心を同じくして前記第１および第２の許容範囲の広くとも２／３の幅を持った範囲内にあることが望ましい。これにより前記気体の流量の変化、言いかえれば気体の流量のバラツキの平均値の変動が収束傾向にある、気体の流れがより安定した状況で測定することとなる。これにより、前記気体の流量変化が小さく、かつ小さく変化する気体の流量の平均値も収束傾向にある時点でハニカム構造体の気体流入側と流出側との差圧を測定し、前記差圧の測定の後の前記気体の流量変化が小さいことを確認することにより、ハニカム構造体の圧力損失をさらに高精度に評価することができ、特に、ハニカム構造体の隔壁の気孔率を５０％以上、平均細孔径を１５μｍ以上などとして圧力損失をさらに小さくした場合での、小さくした圧力損失の微妙な違いをさらに高精度に評価することができる。
ここで、気体の流量が第１の許容範囲とは、例えば１５Ｎｍ^３／ｍｉｎ±０．１Ｎｍ^３／ｍｉｎ以内に、第２の許容範囲とは、第１の許容範囲より狭い、例えば１５Ｎｍ^３／ｍｉｎ±０．０５Ｎｍ^３／ｍｉｎ以内を言う。
【００１６】
また本発明は、繰り返し求めた前記圧力損失のバラツキが±３％以内であることが望ましく、±３％以内であれば高精度に評価されていると言える。特に、ハニカム構造体の隔壁の気孔率を５０％以上、平均細孔径を１５μｍ以上などとして圧力損失をさらに小さくした場合での、小さくした圧力損失の微妙な違いを高精度に評価されていると言える。
【００１７】
また、本発明のハニカム構造体の圧力損失の評価方法は、ハニカム構造体に、気体の流量に対する許容範囲を決めて気体を供給し、前記気体の流量が許容範囲にあるときに測定した前記ハニカム構造体の気体流入側と流出側との差圧の少なくとも２以上の測定値から求めた平均値から、圧力損失を求めることを特徴とするハニカム構造体の圧力損失の評価方法であり、例えば、許容範囲を１０Ｎｍ^３／ｍｉｎ±０．１Ｎｍ^３／ｍｉｎとして気体を供給した場合、測定経過中に気体の流量が許容範囲を満足したときに測定した差圧を１０点抽出し、この１０点の差圧を平均することで、高精度にハニカム構造体の圧力損失を評価することができる。
【００１８】
また、本発明のハニカム構造体の圧力損失の評価方法は、ハニカム構造体に、気体の流量に対する許容範囲を決めて気体を供給し、前記気体の流量が許容範囲にあるときに測定した前記ハニカム構造体の気体流入側と流出側との差圧の少なくとも３以上の測定値から求めた中央値から、圧力損失を求めることを特徴とするハニカム構造体の圧力損失の評価方法であり、例えば、許容範囲を１０Ｎｍ^３／ｍｉｎ±０．１Ｎｍ^３／ｍｉｎとして気体を供給した場合、測定経過に気体の流量が許容範囲を満足したときに測定した差圧を１１点抽出し、この１１点中の中央値の６点目を差圧の測定値とすることで、高精度にハニカム構造体の圧力損失を評価することができる。
【００１９】
また、本発明のハニカム構造体の圧力損失の評価方法においては、前記気体の流量および前記差圧は、前記気体の温度、前記気体の湿度、測定環境の温度、測定環境の湿度、および測定環境の気圧の少なくとも１以上による補正を加えることができる。ハニカム構造体の圧力損失を高精度に評価するために、前記補正を加えることが望ましい。
【００２０】
また、本発明のハニカム構造体の圧力損失の評価方法においては、前記ハニカム構造体に、微粒子を供給することもできる。これにより実際のエンジンの運転状況を想定したＰＭの捕集の状況に応じたハニカム構造体の圧力損失を高精度に評価することができる。
【００２１】
また、上記微粒子はカーボン微粒子とし、該カーボン微粒子の投入速度を１ｇ／ｍｉｎ以下とすることが好ましい。ここで、カーボン微粒子の投入速度を１ｇ／ｍｉｎ以下としたのは、投入速度１ｇ／ｍｉｎを超えると、カーボン微粒子が粒状のかたまりとなって、微粒子の分布が偏り、均一に投入することが難しいためである。よって該カーボン微粒子の投入速度を１ｇ／ｍｉｎ以下とすることが好ましい。
【００２２】
次に、本発明のハニカム構造体の圧力損失の評価装置は、ハニカム構造体を収納する試験用チャンバと、該試験用チャンバの入口側および出口側に接続して、前記ハニカム構造体の気体流入側と流出側との差圧を検出してコンピュータに入力する差圧検出手段と、前記試験用チャンバの出口側に続く送気管の末端に接続して、前記ハニカム構造体に気体を送気する送気手段と、前記送気管中に配置して、前記ハニカム構造体への気体の流量を検出して前記コンピュータに入力する流量検出手段と、前記送気管中に配置して、前記コンピュータとの入出力により前記気体の流量を制御する流量制御手段とを有し、前記コンピュータには、前記ハニカム構造体への前記気体の目標流量と該目標流量に対する許容範囲を記憶しており、前記流量が前記許容範囲にあるときに検出した前記ハニカム構造体の気体流入側と流出側との差圧から、圧力損失を求めるようにしていることを特徴とする。ここで、流量検出手段と流量制御手段の送気管中の配置は前後何れでも良い。これにより、ハニカム構造体の圧力損失をさらに高精度に評価することができ、特に、ハニカム構造体の隔壁の気孔率を５０％以上、平均細孔径を１５μｍ以上などとして圧力損失をさらに小さくした場合での、小さくした圧力損失の微妙な違いをさらに高精度に評価することができる。
【００２３】
また、本発明のハニカム構造体の圧力損失の評価装置においては、前記試験用チャンバの入口側に、フィルタを備えることもできる。これにより、測定環境中に浮遊する塵埃が試験用チャンバ内に流入するを防止すると共に、気体を整流してハニカム構造体に供給することで圧力損失の値の誤差を少なくできる。
【００２４】
また、本発明のハニカム構造体の圧力損失の評価装置においては、前記試験用チャンバの入口側に、前記ハニカム構造体に微粒子を供給する微粒子供給手段を備えることもできる。これにより、ＰＭの捕集の状況に応じたハニカム構造体の圧力損失を高精度に評価することができる。
【００２５】
また、本発明のハニカム構造体の圧力損失の評価装置においては、前記気体の温度検出手段、前記気体の湿度検出手段、測定環境の温度検出手段、測定環境の湿度検出手段、測定環境の気圧検出手段の少なくとも１の検出手段を有し、前記コンピュータが、前記検出手段での検出値をもとに、前記気体の流量、および差圧に補正を加える評価装置とすることが好ましい。これにより、ハニカム構造体の圧力損失を高精度に評価することができる。
【００２６】
【発明の実施の形態】
以下、本発明を具体化した実施の形態の一例を詳細に説明する。なお、以下の説明においては、ＤＰＦおよび触媒コンバータをまとめて「ハニカム構造体」とする。
【００２７】
（実施の形態１）
図１は、実施の形態１において測定されるハニカム構造体１であり、（ａ）はその模式斜視図、（ｂ）は模式断面図である。このハニカム構造体１は、ディーゼルエンジンの排気系に配置されてＰＭを捕集する役割を果たし、強度と共に圧力損失が特に小さいことが要求されている。ハニカム構造体１は、外径２６７ｍｍ×長さ３０４ｍｍの円筒形状でコージェライト材の多孔質セラミック焼結体である。なお、コージェライト材以外にも、例えば炭化硅素、窒化硅素、アルミナなどを選択することができる。ハニカム構造体１には、外皮１ａ内に断面略正方形状の複数の貫通孔１ｂがその軸線方向に沿って規則的に配列されている。各貫通孔１ｂは隔壁１ｃによって互いに隔てられている。貫通孔１ｂの各端面１ｄ、１ｅは各封止材１ｆ、１ｇによって交互に封止されており、端面１ｄ、１ｅ全体としては市松模様になっている。隔壁１ｃは、厚さが０．３ｍｍ、ピッチが１．５ｍｍ、気孔率が６５％、平均細孔径が２０μｍとなっている。
【００２８】
ハニカム構造体１をディーゼルエンジンの排気系に配置したとき、排気ガスは、端面１ｄに開口した貫通孔１ｂから流入（矢印Ａ１）し、多孔質の隔壁１ｃを通過（矢印Ａ２）して隣接する貫通孔から流出（矢印Ａ３）する。このとき、排気ガス中に含まれるＰＭは隔壁１ｃで捕集される。そして、一定量のＰＭが蓄積されるとこれを電気ヒータで燃焼したりして、ハニカム構造体１の再生を行う。
【００２９】
次に、ハニカム構造体１の圧力損失の評価装置について説明する。図２は、ハニカム構造体１の圧力損失の評価装置の一例の模式図である。なお、試験用の気体としては、通常の空気を用いている。図２で、試験用チャンバ３には、緩衝材２を介してハニカム構造体１を収納している。緩衝材２はハニカム構造体１の周囲に巻き付けて試験用チャンバ３への出し入れを容易にすると共にハニカム構造体１を保護している。試験用チャンバ３は、入口側３ａを開いてハニカム構造体１の出し入れをできるようにし、また奥のストッパ（図示せず）でハニカム構造体１と緩衝材２の位置決めができるようにしている。試験用チャンバ３の入口側３ａおよび出口側３ｂには、ハニカム構造体１の差圧を検出してコンピュータ６に入力する差圧計５を接続している。試験用チャンバ３の出口側３ｂに続く送気管７ａには、流入したゴミなどを捕捉するアブソリュートフィルタ８を接続している。アブソリュートフィルタ８に続く送気管７ｂにはハニカム構造体１を通過した空気の流量を検出してコンピュータ６に入力する差圧式流量計１０を接続している。差圧式流量計１０に続く送気管７ｃには、コンピュータ６との入出力により空気の流量を制御する流量調整弁１１を接続している。流量調整弁１１に続く送気管７ｄには、コンピュータ６との入出力により一定出力で空気を吸引する排気送風機１２を接続している。また、試験用チャンバ３の入口側３ａには、測定環境中に浮遊する塵埃が試験用チャンバ３内に流入するを防止すると共に空気を整流してハニカム構造体１に供給するフィルタ４を備えている。
【００３０】
また、アブソリュートフィルタ８の前の送気管７ａには、送気管７ａを流れる空気の温度・湿度を検出して、コンピュータ６に入力するデジタル温度・湿度計９を備えている。フィルタ４の近くには、測定環境の温度・湿度・気圧を検出して、コンピュータ６に入力するデジタル温度・湿度・気圧計１３を備えている。
【００３１】
コンピュータ６には、ハニカム構造体１への空気の目標流量とこの目標流量に対する許容範囲を記憶させている。そして、コンピュータ６は、一定時間ごと同時に、空気の流量と、空気の温度・湿度、測定環境の温度・湿度・気圧のサンプリングを行い、空気の流量が許容範囲にあるときに検出した差圧計５の値に、空気の温度・湿度、測定環境の温度・湿度・気圧をもとに標準状態にする補正をかける演算を行い、圧力損失の値をディスプレイ６ａに表示している。なお、モニタ６ａの表示値が配線のノイズなどで各検出値と異なっている場合、ノイズを除去するように補正している。
【００３２】
次に、圧力損失の評価方法について説明する。
圧力損失には、ハニカム構造体１の圧力損失に加え、試験用チャンバ３の圧力損失も含まれている。このため事前に、ハニカム構造体１を試験用チャンバ３に収納しないで、試験用チャンバ３単独の圧力損失を測定している。通常、標準状態における試験用チャンバ３のみの圧力損失は一定であるので、いったん測定して得られた試験用チャンバ３の圧力損失をコンピュータ６に記憶させ、これを自動的に差し引いて、ハニカム構造体の圧力損失としている。なお、簡易的な圧力損失の評価方法としては、標準状態でない測定環境の場合に、試験用チャンバ３のみの差圧とハニカム構造体１の差圧の両方を測定し、標準状態における試験用チャンバ３の差圧との比からハニカム構造体１の差圧の測定値に補正を加えて標準状態して求めることもできる。
【００３３】
図３は、経過時間・空気の流量・差圧から、ハニカム構造体１の圧力損失を求めるための説明図である。図３では、ハニカム構造体１に、目標流量を１５Ｎｍ^３／ｍｉｎと決めて空気を連続して供給するように、コンピュータ６に入力している。なお、目標流量１５Ｎｍ^３／ｍｉｎは、ディーゼルエンジン実機での排気ガス温度が４００〜６００℃で流量が約３７〜４８Ｎｍ^３／ｍｉｎに相当させている。また、所定時間を１０ｓ（秒）とし、流量の許容範囲を１５±０．１Ｎｍ^３／ｍｉｎとした。そして圧力損失の評価装置を稼動し、ハニカム構造体１を通過する空気の流量を測定し、所定時間１０秒間で空気の流量の許容範囲を満足したときに、空気上流側と下流側との差圧を測定し、前記差圧からハニカム構造体１の圧力損失を求める。図３の例では経過時間６ｓ以降所定時間の１０秒間にて空気流量が許容範囲を満足しているため、経過時間１９ｓのハニカム構造体１の空気流入側と流出側との差圧の値より圧力損失を求めた。同様にハニカム構造体１の圧力損失を繰り返し求めたところ、圧力損失の値のバラツキは３％程度であった。
【００３４】
（実施の形態２）
次に（実施の形態１）と同じ評価装置を用い、ハニカム構造体１の圧力損失を求めた別の方法を図４により説明する。ここでは所定時間を１０ｓとし、この間の流量の許容範囲を１５±０．１Ｎｍ^３／ｍｉｎとした。また、ハニカム構造体１の空気流入側と流出側との差圧の測定後の連続する所定時間を３ｓとした。
図４の例では経過時間４ｓ以降の１０秒間にて空気流量が許容範囲を満足しているため、経過時間１９ｓのハニカム構造体１の空気流入側と流出側との差圧を測定し、ついで１４ｓ以降１６ｓまでの３秒間の空気の流量が許容範囲を満足しているため、先に求めた差圧より圧力損失を求めた。同様にハニカム構造体１の圧力損失を繰り返し求めたところ、圧力損失の値のバラツキは３％以内に収めることが出来た。
【００３５】
（実施の形態３）
次に（実施の形態１）および（実施の形態２）と同じ評価装置を用い、ハニカム構造体１の圧力損失を求めた別の方法を図５により説明する。ここでは所定時間を１０ｓ（秒）間とし、流量の許容範囲（第１の許容範囲）を１５±０．１Ｎｍ^３／ｍｉｎとし、かつ流量の平均を前記第１の許容範囲（１５±０．１Ｎｍ^３／ｍｉｎ）の２／３以下の１５±０．０５Ｎｍ^３／ｍｉｎとして、コンピュータ６に入力している。また、前記所定時間１０ｓ間内での直近短時間を５ｓ間とし、この間の流量の許容範囲（第２の許容範囲）を流量の第１の許容範囲より狭い許容範囲の１５±０．０５Ｎｍ^３／ｍｉｎとし、かつ平均の流量の許容範囲を前記第２の許容範囲の２／３以下の１５±０．０１Ｎｍ^３／ｍｉｎとして、コンピュータ６に入力している。また、差圧の測定後に連続する所定時間を３ｓ間とし、この時間での流量の許容範囲を第２の許容範囲と同じ１５±０．０５Ｎｍ^３／ｍｉｎ以下として、コンピュータ６に入力している。また、差圧は、空気の温度２０℃、相対湿度６５％、気圧１０１３ｈＰａの標準状態に補正して求めている。図５の例では、経過時間１０ｓ以降の所定時間である１０秒間で空気の流量が前記第１の許容範囲である１５±０．１Ｎｍ^３／ｍｉｎを満足し、かつ流量の平均がその許容範囲である１５±０．０５Ｎｍ^３／ｍｉｎを満足している。そして、直近短時間の５ｓ間となる経過時間１５ｓ以降の５ｓ間にて、空気の流量が第２の許容範囲である１５±０．０５Ｎｍ^３／ｍｉｎを満足し、かつ流量の平均がその許容範囲である１５±０．０１Ｎｍ^３／ｍｉｎを満足している。そこで経過時間１９ｓでのハニカム構造体１の空気上流側と下流側との差圧を測定する。ついで、差圧測定後に連続する所定時間である経過時間２０ｓ以降の３ｓ間にて、空気の流量が許容範囲である１５±０．０５Ｎｍ^３／ｍｉｎを満足していることより、先に測定した前記差圧よりハニカム構造体１の圧力損失を求めた。
【００３６】
上記の測定方法により、異なるハニカム構造体１（Ａ，Ｂ）について、測定日を変えて各々８回、差圧を測定した。なお、ハニカム構造体１（Ａ，Ｂ）のみの差圧は、ハニカム構造体１（Ａ，Ｂ）を収納した状態の差圧から、ハニカム構造体１（Ａ，Ｂ）を収納しない試験用チャンバ３の差圧を引いて求めた。その結果を表１に示す。また、図６に、異なるハニカム構造体１（Ａ，Ｂ）についての測定回数ごとの差圧を示す。
【００３７】
（表１）

【００３８】
表１および図６に示すように、測定日を変えても、差圧のバラツキは±２％未満であり、ハニカム構造体１（Ａ，Ｂ）の圧力損失を高精度に評価できていることがわかる。また、ハニカム構造体１（Ａ，Ｂ）で差圧の平均が違っており、微妙な圧力損失の違いを高精度に評価できていることがわかる。
【００３９】
（実施の形態４）
前記実施の形態と同じ評価装置を用い、ハニカム構造体１の圧力損失を求めた別の方法として、空気の流量の許容範囲を１５±０．１Ｎｍ^３／ｍｉｎとし、許容範囲にある時の差圧を１０点抽出し、この１０点の差圧の平均値よりハニカム構造体１の圧力損失を求めた。また、ハニカム構造体１の圧力損失を求めた別の方法として、同様に空気の流量の許容範囲を１５±０．１Ｎｍ^３／ｍｉｎとし、許容範囲にある時の差圧を１１点抽出し、この１１点の差圧の中央値より圧力損失を求めた。これら２つの方法によりハニカム構造体１の圧力損失を繰り返し求めたところ、そのバラツキは何れも３％であった。
【００４０】
（実施の形態５）
図７は、実施の形態３に記した方法にて測定し、供給する空気や測定環境の条件、すなわち空気の温度・湿度、測定環境の温度・湿度・気圧が異なる時（Ｃ、Ｄ）の、同じハニカム構造体１で、経過時間ごとの差圧の変化を示す図である。
ここで測定環境Ｃでは、測定室のエアコンが自動運転されておる状況で測定を行ったものであり、また測定環境Ｄは、測定室のエアコンが運転されていない状況で測定を行ったものである。なお、図７で、点線は、差圧を供給空気の温度・湿度および測定環境の温度・湿度・気圧から補正していない値であり、一方、実線はここでは標準状態に補正した値を示す。図７から、同じハニカム構造体１でも、補正していない場合には、差圧が異なり、しかも経過時間ごとにバラツキを持っているが、補正することで、殆ど一致した値となっている。したがって、差圧を測定するたびに気体の温度・湿度、測定環境の温度・湿度・気圧をもとに、これに補正を施す事が望ましいことが判る。
【００４１】
（実施の形態６）
図８は、実施の形態６での、ＣＲＴに用いられるハニカム構造体１の圧力損失の評価装置の模式図であり、ＰＭにあたるカーボン微粒子をハニカム構造体１に送り、ハニカム構造体１の圧力損失を測定できるようにしている。図８では、前述した実施の形態３と同じ構成のものは同符号で示している。図８の評価装置は、図２での試験用チャンバ３の入口側３ａのフィルタ４を外し、一方、カーボン微粒子１５ａの供給手段を設けている。すなわち、カーボン微粒子１５ａの供給手段は、入口３ａにダストインジェクタ１４の噴出口１４ａを対向させ、ダストインジェクタ１４には２本のチューブ１６を接続している。一方のチューブ１６はカーボン微粒子を貯留しているダストフィーダ１５に、他方のチューブ１６はドライヤ１７を介して空気圧縮機１８に接続している。空気圧縮機１８を作動させ、ダストフィーダ１５とダストインジェクタ１４間の攪拌機（図示せず）により、カーボン微粒子１５ａをダストインジェクタ１４に一定の投入量および速度で送り込んでいる。そして、空気圧縮機１８で圧縮し、またドライヤ１７で乾燥した圧縮空気をダストインジェクタ１４に送ることで、カーボン微粒子１５ａをダストインジェクタ１４に引き込み、カーボン混合気としてハニカム構造体１に向けて噴射している。
【００４２】
実施の形態３と同じように、ハニカム構造体１の圧力損失の評価装置を作動させ、空気が目標流量の１０Ｎｍ^３／ｍｉｎ近くとなり安定した時点で、ダストインジェクタ１４からハニカム構造体１に向けてカーボン微粒子１５ａの投入する。そして、カーボン微粒子１５ａの投入量が２ｇ／ｌ（リットル）になるまで１ｓ（秒）ごとに差圧計５で差圧を検出してコンピュータ６に入力する。コンピュータ６で、実施の形態３と同様に補正を行い圧力損失を求める。図９は、カーボン微粒子１５ａの投入量ごとの補正前と補正後の差圧を示す図である。図９から、補正前は、カーボン微粒子１５ａの投入量ごとの差圧が大きく脈動しているが、補正後は、差圧が安定している。したがって、補正後の差圧をもとに、カーボン微粒子１５ａを投入した際の圧力損失を高精度に評価できることがわかる。
また、ＣＲＴに用いられるハニカム構造体１での、カーボン微粒子１５ａの投入量が２ｇ／ｌ（リットル）になるまでの圧力損失を高精度に評価できることがわかる。
【００４３】
（比較例）
図１０は、単一のハニカム構造体１の差圧を、本発明のハニカム構造体の圧力損失の評価方法および評価装置を用いて測定したものと、用いずに測定したものの比較を表す図である。この図の横軸は、日に１回測定したときの測定回数を示している。図１０に示すように、本発明のハニカム構造体の圧力損失の評価方法および評価装置を用いて測定したものは、用いずに測定したものに比較して、差圧のバラツキが小さく、本発明のハニカム構造体の評価方法および評価装置によるのが有効であることがわかる。
【００４４】
なお、実施の形態では、多孔質セラミック焼結体からなるハニカム構造体について説明したが、これに限らず、耐熱合金からなるハニカム構造体についても本発明のハニカム構造体の圧力損失の評価方法および評価装置を適用できることは言うまでもない。
【００４５】
【発明の効果】
以上、詳細に説明のとおり、本発明のハニカム構造体の評価方法および評価装置によれば、ハニカム構造体の圧力損失を高精度に評価することができる。特に、ハニカム構造体の隔壁の気孔率を５０％以上、平均細孔径を１５μｍ以上などとして圧力損失をさらに小さくした場合での、小さくした圧力損失の微妙な違いを高精度に評価することができる。
【図面の簡単な説明】
【図１】実施の形態１において圧力損失を測定するハニカム構造体１であり、（ａ）はその模式斜視図、（ｂ）は模式断面図である。
【図２】実施の形態１での、ハニカム構造体１の圧力損失の評価装置の一例の模式図である。
【図３】実施の形態１での、経過時間・空気の流量・差圧から、ハニカム構造体１の圧力損失を求めるための説明図である。
【図４】実施の形態２での、経過時間・空気の流量・差圧から、ハニカム構造体１の圧力損失を求めるための説明図である。
【図５】実施の形態３での、経過時間・空気の流量・差圧から、ハニカム構造体１の圧力損失を求めるための説明図である。
【図６】実施の形態３での、異なるハニカム構造体１（Ａ，Ｂ）についての測定回数ごとの差圧を示す図である。
【図７】実施の形態５での、図２の圧力損失の評価装置を用い、供給する空気や測定環境の条件、すなわち空気の温度・湿度、測定環境の温度・湿度・気圧が異なる、同じハニカム構造体１（Ｃ，Ｄ）で、経過時間ごとの差圧の変化を示す図である。
【図８】実施の形態６での、ＣＲＴに用いられるハニカム構造体１の圧力損失の評価装置の模式図である。
【図９】実施の形態６での、カーボン微粒子１５ａの投入量ごとの補正前と補正後の差圧を示す図である。
【図１０】比較例での、本発明のハニカム構造体の圧力損失の評価方法および評価装置によらずに測定した、異なるハニカム構造体１（Ｅ，Ｆ）の流量および差圧を示す図である。
【符号の説明】
１ハニカム構造体（ＤＰＦ、触媒コンバータ）
１ａ外皮
１ｂ貫通孔
１ｃ隔壁
１ｄ、１ｅ端面
１ｆ、１ｇ封止材
２緩衝材
３試験用チャンバ
３ａ入口側
３ｂ出口側
４フィルタ
５差圧計
６コンピュータ
６ａモニタ
７ａ、７ｂ、７ｃ、７ｄ送気管
８アブソリュートフィルタ
９デジタル温度・湿度計
１０差圧式流量計
１１流量調整弁
１２排気送風機
１３デジタル温度・湿度・気圧計
１４ダストインジェクタ
１４ａ噴出口
１５ダストフィーダ
１５ａカーボン微粒子
１６チューブ
１７ドライヤ
１８空気圧縮機
Ａ１流入
Ａ２通過
Ａ３流出[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for evaluating pressure loss of a honeycomb structure used for purifying exhaust gas.
[0002]
[Prior art]
Exhaust gas purifying honeycomb structures used to purify exhaust gas from internal combustion engines such as diesel engines and gasoline engines are generally made of heat-resistant materials such as ceramics or metals, and are incorporated into the exhaust system of internal combustion engines. It plays a role in removing harmful substances contained in exhaust gas. The exhaust gas purifying honeycomb structure has a function of removing a target harmful substance by supporting a catalytic substance, and a particulate matter (Particulate Matters, hereinafter referred to as “PM”) mainly in exhaust gas of a diesel engine. There is also a honeycomb structure for a diesel particulate filter (hereinafter referred to as DPF) in which the above-mentioned honeycomb structure filters and captures and contributes to purification of exhaust gas.
[0003]
The exhaust gas purifying honeycomb structure obstructs the flow of exhaust gas due to its pressure loss, which causes a decrease in engine output. Further, in the honeycomb structure for DPF, as PM in exhaust gas is captured and accumulated inside the honeycomb structure for DPF, pressure loss increases and engine output decreases. For this reason, it is necessary to grasp the initial pressure loss of the honeycomb structure and the pressure loss after accumulation of PM.
[0004]
By the way, the `` pressure loss '' of the honeycomb structure is obtained by subtracting the pressure value of the gas on the downstream side from the pressure value of the gas on the upstream side of the honeycomb structure when the gas passes through the honeycomb structure. The greatest factor is the resistance of the gas as it passes through the honeycomb structure. Therefore, it is necessary to appropriately set the material, thickness, porosity, pore diameter, and the like of the partition walls of the honeycomb structure, and the shape of the inlet end of the honeycomb structure into which the exhaust gas flows.
[0005]
As a means for obtaining and evaluating the pressure loss of the honeycomb structure, there is a method for testing an automobile air cleaner according to Japanese Industrial Standards (JIS) (for example, see Non-Patent Document 1). The test apparatus disclosed in Non-Patent Document 1 includes a test chamber for accommodating a test sample (an automobile air cleaner in JIS), a differential pressure gauge connected to an outlet side and an inlet side of the test chamber, and an air pipe in order from the outlet side. It consists of an absolute filter, an air flow meter, an air flow control device, an exhaust blower, etc.
When the pressure loss of the honeycomb structure serving as a specimen is determined by the test device of Non-Patent Document 1, air in a test chamber is allowed to flow for 15 minutes or more, and then the pressure loss is determined by a differential pressure gauge. Further, the values such as the air amount and the differential pressure are corrected to the standard condition of 20 ° C., the relative humidity of 65%, and the atmospheric pressure of 1013 hPa, and the pressure loss is obtained. Further, for example, a method of incorporating the honeycomb structure into an exhaust system of an internal combustion engine as in the invention described in Patent Literature 1 and correcting the obtained pressure loss with the exhaust flow rate of the engine, or a method as disclosed in Patent Literature 2 It is described that a gas containing particles is sent to the honeycomb structure by a particle-containing gas generator without using an internal combustion engine, and a pressure loss is obtained from a differential pressure between a gas inflow side and an outflow side of the honeycomb structure. . Since these are all measured after the pressure loss has increased, the pressure loss is relatively easily obtained.
[0006]
In the DPF honeycomb structure, when a certain amount of PM is accumulated, it is necessary to burn the PM with an electric heater or remove the PM with backwash air to regenerate the DPF. In the method of burning and regenerating the fine particles, there is a problem that the honeycomb structure itself for DPF is melted and damaged by self-heating of the fine particles, and the apparatus becomes complicated when backwash air is used. A technique (CRT system) for continuously burning fine particles in a honeycomb structure has been adopted.
[0007]
[Non-patent document 1]
JIS D 1612-1989 Test method for air cleaner for automobiles [

Page

4, 8. Item (air flow resistance test), p. Item (15) (air flow resistance), page 24 (dust for test), page 27 (FIG. 6 testing device for cleaning efficiency and dust holding amount for panel-type filter element), pages 32 to 34 (air volume relative to standard condition) And correction of airflow resistance)]
[Patent Document 1]
JP-A-8-109818
[Patent Document 2]
Japanese Patent No. 2807370
[0008]
[Problems to be solved by the invention]
In the CRT system, in the steady state, PM is continuously burned off and is not accumulated, and therefore, there is almost no increase in pressure loss due to PM accumulation. Further, in a CRT system, it is essential to dispose a honeycomb structure carrying an oxidation catalyst on the upstream side of the honeycomb structure for DPF. In some cases, it is necessary to dispose a honeycomb structure carrying a catalyst for removing NOx downstream of the honeycomb structure for DPF, which increases the pressure loss of the entire exhaust system of the internal combustion engine and leads to a decrease in engine output. Therefore, the pressure loss of the DPF honeycomb structure itself is reduced, for example, by using a material having a porosity of 50% or more and an average pore diameter of 15 μm or more and optimizing the cell structure. Technological development to keep the pressure low is underway, and it is necessary to accurately obtain a low pressure loss in order to perform the evaluation and inspection.
[0009]
However, even if the pressure loss is determined for such a honeycomb structure for a DPF using the test method for an air cleaner for an automobile or the method for determining the pressure loss described in the patent document, the pressure loss itself is extremely small. From the above, the influence of the flow rate and temperature and humidity of the gas flowing through the honeycomb structure for DPF and the slight change in the atmospheric pressure, temperature and humidity of the measurement environment appear as a large variation in the value of the pressure loss, and the pressure loss is accurately obtained. It is difficult. In particular, regarding the change in the gas flow rate, the influence of the minute flow rate change that still exists even when a device for stabilizing the flow rate such as a flow control valve, on the value of the pressure loss cannot be ignored. Therefore, even if it is considered that the pressure loss differs between different honeycomb structures, the difference does not appear, and the pressure loss cannot be obtained with high accuracy.
[0010]
Therefore, an object of the present invention is to provide a method and an apparatus for evaluating the pressure loss of a honeycomb structure, which can accurately determine the pressure loss of the honeycomb structure. In particular, when the porosity of the partition walls of the honeycomb structure is 50% or more, the average pore diameter is 15 μm or more, and the pressure loss is further reduced, a subtle difference in the reduced pressure loss can be obtained with high accuracy. An object of the present invention is to provide a method and an apparatus for evaluating pressure loss of a honeycomb structure.
[0011]
[Means for Solving the Problems]
The present inventors have intensively studied the above problem. As a result, it was found that the change in the flow rate of gas supplied to the honeycomb structure was small, and the pressure loss of the honeycomb structure could be determined with high accuracy by measuring the differential pressure when a stable flow was maintained. Thus, the present invention has been made.
[0012]
That is, the evaluation method of the pressure loss of the honeycomb structure of the present invention, the gas is continuously supplied to the honeycomb structure to determine an allowable range for the flow rate of the gas, and the flow rate of the gas is within the allowable range within a predetermined time. A pressure loss of the honeycomb structure is obtained from a pressure difference between a gas inflow side and an outflow side of the honeycomb structure measured at a certain time.
Thereby, the pressure loss of the honeycomb structure is measured with high accuracy by measuring the differential pressure between the gas inflow side and the outflow side of the honeycomb structure in a state where the gas flow rate change is small and a stable flow is maintained. In particular, when the porosity of the partition walls of the honeycomb structure is 50% or more and the average pore diameter is 15 μm or more, the pressure loss is further reduced. Can be evaluated.
[0013]
Here, that the gas flow rate is within the allowable range is, for example, 30 Nm. ³ / Min, tolerance is ± 0.9Nm ³ / Min. The measurement of the differential pressure is performed not only when the flow rate of the gas is within an allowable range within a predetermined time, but also when the flow rate of the gas is within an allowable range within a predetermined time. Needless to say, it is also possible to obtain the pressure loss by extracting only the differential pressure.
[0014]
In addition, the method for evaluating pressure loss of a honeycomb structure according to the present invention includes the steps of: determining an allowable range for a gas flow rate and continuously supplying the gas to the honeycomb structure; When the pressure difference between the gas inflow side and the outflow side of the honeycomb structure is measured, and then when the flow rate of the gas is within the allowable range within a predetermined time continuous after the measurement of the differential pressure, Alternatively, a method of obtaining a pressure loss from the differential pressure may be adopted. Thereby, the differential pressure between the gas inflow side and the outflow side of the honeycomb structure is measured in a state where the change in the flow rate of the gas is small and a stable flow is maintained, and the flow rate of the gas after the measurement of the differential pressure is measured. By confirming that the change is small, the pressure loss of the honeycomb structure can be more accurately evaluated. In particular, the porosity of the partition walls of the honeycomb structure is 50% or more, and the average pore diameter is 15 μm or more. When the pressure loss is further reduced, a subtle difference in the reduced pressure loss can be evaluated with high accuracy.
Here, within a certain elapsed time period is, for example, 10 seconds (seconds), and within a predetermined time period after the measurement of the differential pressure is, for example, 3 seconds following the 10 seconds.
[0015]
In addition, the method for evaluating pressure loss of a honeycomb structure according to the present invention includes the steps of: determining an allowable range for a flow rate of a gas; and continuously supplying the gas to the honeycomb structure; In the allowable range, the average of the flow rates of the gas is within the range having a width of at most 2/3 of the first allowable range within the predetermined time and having the same center as the first allowable range. And a flow rate of the gas in the latest short time within the predetermined time is a second allowable range narrower than the first allowable range, and an average of the flow rates of the gas in the latest short time is the second allowable range. When the second allowable range is at most within a range having a width of 2/3 at the center, the differential pressure between the gas inflow side and the outflow side of the honeycomb structure is measured. The gas flow rate within the continuous predetermined time after the measurement of the differential pressure When in tolerance can also take the method of obtaining the pressure loss from the differential pressure. Here, the average of the flow rates of the gas is within a range having a width of at most 2/3 of the first and second allowable ranges with the same center as the first and second allowable ranges. Is desirable. As a result, the measurement is performed in a situation where the flow of the gas is more stable, in which the change in the flow rate of the gas, in other words, the variation in the average value of the variation in the flow rate of the gas tends to converge. Thereby, the pressure difference between the gas inflow side and the gas outflow side of the honeycomb structure is measured at a point in time when the change in the gas flow rate is small and the average value of the gas flow rate that changes small also tends to converge. By confirming that the change in the flow rate of the gas after the measurement is small, the pressure loss of the honeycomb structure can be evaluated with higher accuracy. In particular, the porosity of the partition wall of the honeycomb structure is 50% or more, When the pressure loss is further reduced by setting the average pore diameter to 15 μm or more, a delicate difference in the reduced pressure loss can be evaluated with higher accuracy.
Here, the gas flow rate is the first allowable range, for example, 15 Nm. ³ /Min±0.1Nm ³ / Min, the second allowable range is smaller than the first allowable range, for example, 15 Nm. ³ /Min±0.05Nm ³ / Min.
[0016]
Further, in the present invention, it is desirable that the variation of the pressure loss repeatedly obtained is within ± 3%, and if it is within ± 3%, it can be said that the evaluation is performed with high accuracy. In particular, when the porosity of the partition walls of the honeycomb structure is 50% or more, the average pore diameter is 15 μm or more, and the pressure loss is further reduced, the subtle difference in the reduced pressure loss is evaluated with high accuracy. I can say.
[0017]
The method for evaluating the pressure loss of a honeycomb structure according to the present invention includes the steps of: supplying a gas to a honeycomb structure with a permissible range for a gas flow rate; measuring the honeycomb when the gas flow rate is within a permissible range; A method for evaluating the pressure loss of a honeycomb structure, wherein a pressure loss is obtained from an average value obtained from at least two measured values of a differential pressure between a gas inlet side and an outlet side of the structure. Allowable range is 10Nm ³ /Min±0.1Nm ³ When the gas is supplied at a rate of / min, 10 points of the differential pressure measured when the flow rate of the gas satisfies the allowable range during the measurement are extracted, and the differential pressures at the 10 points are averaged to obtain a highly accurate honeycomb. The pressure loss of the structure can be evaluated.
[0018]
The method for evaluating the pressure loss of a honeycomb structure according to the present invention includes the steps of: supplying a gas to a honeycomb structure with a permissible range for a gas flow rate; measuring the honeycomb when the gas flow rate is within a permissible range; A pressure loss evaluation method for a honeycomb structure, wherein a pressure loss is obtained from a median obtained from at least three or more measured values of a differential pressure between a gas inflow side and an outflow side of the structure. Allowable range is 10Nm ³ /Min±0.1Nm ³ When the gas is supplied at a rate of / min, 11 points of the differential pressure measured when the flow rate of the gas satisfies the allowable range during the measurement process are extracted, and the sixth point of the median of the 11 points is the measured value of the differential pressure. By doing so, the pressure loss of the honeycomb structure can be evaluated with high accuracy.
[0019]
Further, in the method for evaluating a pressure loss of a honeycomb structure according to the present invention, the flow rate of the gas and the differential pressure are the temperature of the gas, the humidity of the gas, the temperature of the measurement environment, the humidity of the measurement environment, and the measurement environment. Can be corrected by at least one of the atmospheric pressures. In order to evaluate the pressure loss of the honeycomb structure with high accuracy, it is desirable to make the correction.
[0020]
Further, in the method for evaluating pressure loss of a honeycomb structure of the present invention, fine particles may be supplied to the honeycomb structure. Thereby, the pressure loss of the honeycomb structure according to the PM trapping state assuming the actual operation state of the engine can be evaluated with high accuracy.
[0021]
Preferably, the fine particles are carbon fine particles, and the charging rate of the carbon fine particles is 1 g / min or less. Here, the reason why the charging speed of the carbon fine particles is set to 1 g / min or less is that if the charging speed exceeds 1 g / min, the carbon fine particles become granular clumps, the distribution of the fine particles is biased, and it is difficult to uniformly input the fine particles. That's why. Therefore, it is preferable that the charging speed of the carbon fine particles is 1 g / min or less.
[0022]
Next, the apparatus for evaluating pressure loss of a honeycomb structure according to the present invention includes a test chamber for accommodating the honeycomb structure, and a test chamber connected to an inlet side and an outlet side of the test chamber. A differential pressure detecting means for detecting a differential pressure between the pressure side and the outflow side and inputting the same to a computer, and connected to an end of an air supply pipe connected to an outlet side of the test chamber to supply gas to the honeycomb structure. Air supply means, disposed in the air supply pipe, flow rate detection means for detecting the flow rate of gas to the honeycomb structure and input to the computer, and disposed in the air supply pipe, the computer and Flow rate control means for controlling the flow rate of the gas by input and output, the computer stores a target flow rate of the gas to the honeycomb structure and an allowable range for the target flow rate, the flow rate is Previous From the differential pressure between the gas inlet side and the outlet side of the honeycomb structure is detected when in the acceptable range, characterized in that it is to obtain the pressure loss. Here, the arrangement of the flow detecting means and the flow controlling means in the air supply pipe may be either before or after. As a result, the pressure loss of the honeycomb structure can be evaluated with higher accuracy. In particular, when the porosity of the partition walls of the honeycomb structure is 50% or more and the average pore diameter is 15 μm or more, the pressure loss is further reduced. Thus, the subtle difference in the reduced pressure loss can be evaluated with higher accuracy.
[0023]
Further, in the apparatus for evaluating pressure loss of a honeycomb structure according to the present invention, a filter may be provided on an inlet side of the test chamber. This prevents dust floating in the measurement environment from flowing into the test chamber, and reduces errors in the value of pressure loss by rectifying gas and supplying the gas to the honeycomb structure.
[0024]
Further, in the apparatus for evaluating pressure loss of a honeycomb structure according to the present invention, a fine particle supply means for supplying fine particles to the honeycomb structure may be provided on the entrance side of the test chamber. Thereby, the pressure loss of the honeycomb structure according to the PM trapping state can be evaluated with high accuracy.
[0025]
Further, in the apparatus for evaluating pressure loss of a honeycomb structure according to the present invention, the gas temperature detecting means, the gas humidity detecting means, the measuring environment temperature detecting means, the measuring environment humidity detecting means, and the measuring environment pressure detecting means are provided. It is preferable that the computer has at least one detecting means, and the computer is an evaluation device that corrects the flow rate and the differential pressure of the gas based on a value detected by the detecting means. Thereby, the pressure loss of the honeycomb structure can be evaluated with high accuracy.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment embodying the present invention will be described in detail. In the following description, the DPF and the catalytic converter are collectively referred to as a “honeycomb structure”.
[0027]
(Embodiment 1)
FIG. 1 shows a honeycomb structure 1 measured in the first embodiment, wherein (a) is a schematic perspective view and (b) is a schematic cross-sectional view. The honeycomb structure 1 is disposed in an exhaust system of a diesel engine and plays a role of trapping PM, and is required to have particularly small pressure loss as well as strength. The honeycomb structure 1 is a porous ceramic sintered body of cordierite material having a cylindrical shape with an outer diameter of 267 mm and a length of 304 mm. In addition to the cordierite material, for example, silicon carbide, silicon nitride, alumina, or the like can be selected. In the honeycomb structure 1, a plurality of through-holes 1b having a substantially square cross section are regularly arranged in the outer skin 1a along the axial direction. Each through hole 1b is separated from each other by a partition wall 1c. The end surfaces 1d and 1e of the through hole 1b are alternately sealed by the sealing

materials

1f and 1g, and the entire end surfaces 1d and 1e have a checkered pattern. The partition wall 1c has a thickness of 0.3 mm, a pitch of 1.5 mm, a porosity of 65%, and an average pore diameter of 20 μm.
[0028]
When the honeycomb structure 1 is arranged in an exhaust system of a diesel engine, exhaust gas flows in from a through hole 1b opened in an end face 1d (arrow A1), passes through a porous partition wall 1c (arrow A2), and is adjacent. It flows out from the through hole (arrow A3). At this time, PM contained in the exhaust gas is collected by the partition 1c. Then, when a certain amount of PM is accumulated, the PM is burned by an electric heater to regenerate the honeycomb structure 1.
[0029]
Next, a device for evaluating the pressure loss of the honeycomb structure 1 will be described. FIG. 2 is a schematic view of an example of the evaluation device for the pressure loss of the honeycomb structure 1. Note that ordinary air is used as the test gas. In FIG. 2, a honeycomb structure 1 is housed in a test chamber 3 via a buffer material 2. The cushioning material 2 is wrapped around the honeycomb structure 1 to facilitate insertion into and removal from the test chamber 3 and protects the honeycomb structure 1. The test chamber 3 has an inlet side 3a opened so that the honeycomb structure 1 can be taken in and out, and a stopper (not shown) at the back can position the honeycomb structure 1 and the cushioning material 2. A differential pressure gauge 5 that detects a differential pressure of the honeycomb structure 1 and inputs the differential pressure to a computer 6 is connected to the inlet side 3a and the outlet side 3b of the test chamber 3. An absolute filter 8 for catching inflowed dust and the like is connected to an air supply pipe 7a following the outlet side 3b of the test chamber 3. A differential pressure type flowmeter 10 for detecting a flow rate of the air passing through the honeycomb structure 1 and inputting the detected flow rate to a computer 6 is connected to an air supply pipe 7 b following the absolute filter 8. An air supply pipe 7c connected to the differential pressure type flow meter 10 is connected to a flow control valve 11 for controlling the flow rate of air by inputting and outputting from the computer 6. An exhaust blower 12 that sucks air at a constant output by inputting and outputting to and from a computer 6 is connected to an air supply pipe 7 d following the flow rate adjustment valve 11. In addition, a filter 4 is provided on the entrance side 3a of the test chamber 3 to prevent dust floating in the measurement environment from flowing into the test chamber 3 and to rectify the air and supply the air to the honeycomb structure 1. I have.
[0030]
The air supply pipe 7a in front of the absolute filter 8 is provided with a digital temperature / humidity meter 9 for detecting the temperature and humidity of the air flowing through the air supply pipe 7a and inputting it to the computer 6. A digital temperature / humidity / barometer 13 is provided near the filter 4 for detecting the temperature, humidity, and pressure of the measurement environment and inputting it to the computer 6.
[0031]
The computer 6 stores a target flow rate of air to the honeycomb structure 1 and an allowable range for the target flow rate. The computer 6 simultaneously samples the air flow rate, air temperature / humidity, and the temperature / humidity / atmospheric pressure of the measurement environment at regular time intervals, and detects the differential pressure gauge 5 detected when the air flow rate is within an allowable range. Is calculated based on the temperature / humidity of the air and the temperature / humidity / barometric pressure of the measurement environment, and the value of the pressure loss is displayed on the display 6a. When the display value of the monitor 6a is different from each detection value due to wiring noise or the like, correction is made to remove the noise.
[0032]
Next, a method for evaluating pressure loss will be described.
The pressure loss includes the pressure loss of the test chamber 3 in addition to the pressure loss of the honeycomb structure 1. Therefore, the pressure loss of the test chamber 3 alone is measured in advance without storing the honeycomb structure 1 in the test chamber 3. Normally, the pressure loss of only the test chamber 3 in the standard state is constant. Therefore, the pressure loss of the test chamber 3 once measured is stored in the computer 6 and automatically subtracted to obtain the honeycomb structure. With body pressure loss. As a simple method for evaluating pressure loss, in a measurement environment other than the standard state, both the differential pressure of the test chamber 3 and the differential pressure of the honeycomb structure 1 are measured, and the test chamber in the standard state is measured. The measured value of the differential pressure of the honeycomb structure 1 may be corrected based on the ratio with respect to the differential pressure of No. 3 to obtain the standard value.
[0033]
FIG. 3 is an explanatory diagram for obtaining the pressure loss of the honeycomb structure 1 from the elapsed time, the flow rate of the air, and the differential pressure. In FIG. 3, the target flow rate of the honeycomb structure 1 is set to 15 Nm. ³ / Min is input to the computer 6 so as to supply air continuously. In addition, target flow rate 15Nm ³ / Min is an exhaust gas temperature of 400 to 600 ° C. and a flow rate of about 37 to 48 Nm in an actual diesel engine. ³ / Min. The predetermined time is 10 s (seconds), and the allowable range of the flow rate is 15 ± 0.1 Nm. ³ / Min. Then, the pressure loss evaluation device is operated, and the flow rate of the air passing through the honeycomb structure 1 is measured. When the allowable range of the air flow rate is satisfied for a predetermined time of 10 seconds, the difference between the air upstream side and the downstream side is determined. The pressure is measured, and the pressure loss of the honeycomb structure 1 is determined from the differential pressure. In the example of FIG. 3, since the air flow rate satisfies the allowable range for a predetermined time of 10 seconds after the elapsed time of 6 s, the value of the differential pressure between the air inflow side and the outflow side of the honeycomb structure 1 at the elapsed time of 19 s The pressure loss was determined. Similarly, when the pressure loss of the honeycomb structure 1 was repeatedly obtained, the variation in the value of the pressure loss was about 3%.
[0034]
(Embodiment 2)
Next, another method for determining the pressure loss of the honeycomb structure 1 using the same evaluation device as in (Embodiment 1) will be described with reference to FIG. Here, the predetermined time is 10 s, and the allowable range of the flow rate during this period is 15 ± 0.1 Nm. ³ / Min. Further, a continuous predetermined time after the measurement of the differential pressure between the air inflow side and the outflow side of the honeycomb structure 1 was set to 3 s.
In the example of FIG. 4, since the air flow rate satisfies the allowable range for 10 seconds after the elapsed time of 4 s, the differential pressure between the air inflow side and the outflow side of the honeycomb structure 1 during the elapsed time of 19 s was measured. Since the flow rate of air for 3 seconds from 14 s to 16 s satisfies the allowable range, the pressure loss was determined from the differential pressure determined previously. Similarly, when the pressure loss of the honeycomb structure 1 was repeatedly obtained, the variation in the value of the pressure loss could be kept within 3%.
[0035]
(Embodiment 3)
Next, another method of obtaining the pressure loss of the honeycomb structure 1 using the same evaluation device as in (Embodiment 1) and (Embodiment 2) will be described with reference to FIG. Here, the predetermined time is set to 10 seconds (seconds), and the allowable range of the flow rate (first allowable range) is 15 ± 0.1 Nm. ³ / Min, and average the flow rate in the first allowable range (15 ± 0.1 Nm ³ / Min) of 15 ± 0.05 Nm of 2/3 or less ³ / Min is input to the computer 6. Further, the latest short time within the predetermined time 10 s is set to 5 s, and the allowable range of the flow rate (second allowable range) during this time is set to 15 ± 0.05 Nm which is a narrower allowable range than the first allowable range of the flow rate. ³ / Min, and the allowable range of the average flow rate is 15 ± 0.01 Nm which is ／ or less of the second allowable range. ³ / Min is input to the computer 6. Further, the predetermined time continuous after the measurement of the differential pressure is set to 3 seconds, and the allowable range of the flow rate at this time is the same as the second allowable range of 15 ± 0.05 Nm. ³ / Min or less is input to the computer 6. Further, the differential pressure is obtained by correcting the pressure to the standard condition of the air temperature of 20 ° C., the relative humidity of 65%, and the atmospheric pressure of 1013 hPa. In the example of FIG. 5, the air flow rate is 15 ± 0.1 Nm which is the first allowable range in 10 seconds which is a predetermined time after the elapsed time of 10 s. ³ / Min, and the average flow rate is within the allowable range of 15 ± 0.05 Nm. ³ / Min. The air flow rate is set within the second allowable range of 15 ± 0.05 Nm during a period of 5 s after the elapsed time of 15 s, which is the latest short period of 5 s. ³ / Min, and the average of the flow rate is within the allowable range of 15 ± 0.01 Nm. ³ / Min. Therefore, the differential pressure between the upstream side and the downstream side of the honeycomb structure 1 at the elapsed time of 19 s is measured. Then, during a period of 3 s after an elapsed time of 20 s, which is a predetermined period of time after the differential pressure measurement, the air flow rate is within the allowable range of 15 ± 0.05 Nm ³ / Min, the pressure loss of the honeycomb structure 1 was determined from the previously measured differential pressure.
[0036]
According to the above-described measurement method, the differential pressure was measured eight times for different honeycomb structures 1 (A, B) on different measurement dates. In addition, the differential pressure of only the honeycomb structure 1 (A, B) is calculated from the differential pressure in the state where the honeycomb structure 1 (A, B) is stored, from the test chamber not storing the honeycomb structure 1 (A, B). The differential pressure of 3 was subtracted. Table 1 shows the results. FIG. 6 shows the differential pressure of each of the different honeycomb structures 1 (A, B) for each number of measurements.
[0037]
(Table 1)

[0038]
As shown in Table 1 and FIG. 6, even if the measurement date is changed, the variation of the differential pressure is less than ± 2%, and the pressure loss of the honeycomb structure 1 (A, B) can be evaluated with high accuracy. I understand. In addition, it can be seen that the average of the differential pressure is different in the honeycomb structure 1 (A, B), and that a delicate difference in pressure loss can be evaluated with high accuracy.
[0039]
(Embodiment 4)
As another method for obtaining the pressure loss of the honeycomb structure 1 using the same evaluation apparatus as the above embodiment, the allowable range of the air flow rate is set to 15 ± 0.1 Nm. ³ / Min, and 10 points of differential pressure when in the allowable range were extracted, and the pressure loss of the honeycomb structure 1 was determined from the average value of the 10 points of differential pressure. As another method for obtaining the pressure loss of the honeycomb structure 1, similarly, the allowable range of the air flow rate is set to 15 ± 0.1 Nm. ³ / Min, and 11 points of differential pressure when in the allowable range were extracted, and the pressure loss was calculated from the median value of the 11 points of differential pressure. When the pressure loss of the honeycomb structure 1 was repeatedly obtained by these two methods, the variation was 3% in each case.
[0040]
(Embodiment 5)
FIG. 7 is a diagram illustrating the case where the measurement is performed by the method described in Embodiment 3 and the conditions of the supplied air and the measurement environment, that is, the temperature / humidity of the air and the temperature / humidity / pressure of the measurement environment are different (C, D). FIG. 5 is a diagram showing a change in differential pressure for each elapsed time in the same honeycomb structure 1.
Here, in the measurement environment C, the measurement was performed in a state where the air conditioner in the measurement room was automatically operated, and in the measurement environment D, the measurement was performed in a state where the air conditioner in the measurement room was not operated. is there. In FIG. 7, the dotted line is a value obtained by correcting the differential pressure from the temperature / humidity of the supply air and the temperature / humidity / barometric pressure of the measurement environment, while the solid line represents a value corrected to the standard state. . From FIG. 7, even when the same honeycomb structure 1 is not corrected, the differential pressure is different and varies with the lapse of time, but the values almost match by correction. Therefore, it can be seen that it is desirable to make correction based on the temperature / humidity of the gas and the temperature / humidity / barometric pressure of the measurement environment each time the differential pressure is measured.
[0041]
(Embodiment 6)
FIG. 8 is a schematic diagram of an apparatus for evaluating the pressure loss of the honeycomb structure 1 used in the CRT according to the sixth embodiment, in which carbon fine particles corresponding to PM are sent to the honeycomb structure 1 and the pressure loss of the honeycomb structure 1 is reduced. Can be measured. In FIG. 8, components having the same configuration as in the above-described third embodiment are denoted by the same reference numerals. 8 removes the filter 4 on the inlet side 3a of the test chamber 3 in FIG. 2, and provides a supply means for carbon fine particles 15a. That is, the supply means of the carbon fine particles 15a is such that the ejection port 14a of the dust injector 14 faces the inlet 3a, and two tubes 16 are connected to the dust injector 14. One tube 16 is connected to a dust feeder 15 storing fine carbon particles, and the other tube 16 is connected to an air compressor 18 via a dryer 17. The air compressor 18 is operated, and the fine carbon particles 15a are fed into the dust injector 14 at a constant input amount and speed by a stirrer (not shown) between the dust feeder 15 and the dust injector 14. Then, the compressed air compressed by the air compressor 18 and dried by the dryer 17 is sent to the dust injector 14, whereby the carbon fine particles 15a are drawn into the dust injector 14, and are injected as a carbon mixture toward the honeycomb structure 1. ing.
[0042]
In the same manner as in the third embodiment, the evaluation device for the pressure loss of the honeycomb structure 1 is operated, and the air is supplied to the target flow rate of 10 Nm. ³ / Min, and at the time of stabilization, the fine carbon particles 15a are charged from the dust injector 14 toward the honeycomb structure 1. Then, the differential pressure is detected by the differential pressure gauge 5 every 1 s (second) until the input amount of the carbon fine particles 15 a becomes 2 g / l (liter), and is input to the computer 6. The computer 6 performs correction in the same manner as in the third embodiment to obtain a pressure loss. FIG. 9 is a diagram showing the differential pressure before and after the correction for each input amount of the carbon fine particles 15a. From FIG. 9, before the correction, the differential pressure for each input amount of the carbon fine particles 15 a pulsates greatly, but after the correction, the differential pressure is stable. Therefore, it is understood that the pressure loss when the carbon fine particles 15a are introduced can be evaluated with high accuracy based on the corrected differential pressure.
Further, it can be seen that the pressure loss in the honeycomb structure 1 used for the CRT until the input amount of the carbon fine particles 15a becomes 2 g / l (liter) can be evaluated with high accuracy.
[0043]
(Comparative example)
FIG. 10 is a diagram showing a comparison between the pressure difference of a single honeycomb structure 1 measured using the evaluation method and the evaluation device of the pressure loss of the honeycomb structure of the present invention and that measured without using the same. is there. The horizontal axis of this figure indicates the number of measurements performed once a day. As shown in FIG. 10, the honeycomb structure obtained by using the evaluation method and the evaluation device for pressure loss of the honeycomb structure according to the present invention has a smaller variation in the differential pressure as compared with those measured without using the honeycomb structure. It can be seen that the evaluation method and the evaluation apparatus for the honeycomb structure described above are effective.
[0044]
In the embodiment, the description has been given of the honeycomb structure made of a porous ceramic sintered body. However, the present invention is not limited thereto, and the honeycomb structure made of a heat-resistant alloy may be used for evaluating the pressure loss of the honeycomb structure of the present invention. It goes without saying that the evaluation device can be applied.
[0045]
【The invention's effect】
As described above in detail, according to the method and the apparatus for evaluating a honeycomb structure of the present invention, the pressure loss of the honeycomb structure can be evaluated with high accuracy. In particular, when the porosity of the partition walls of the honeycomb structure is 50% or more and the average pore diameter is 15 μm or more, and the pressure loss is further reduced, a subtle difference in the reduced pressure loss can be evaluated with high accuracy. .
[Brief description of the drawings]
FIG. 1 shows a honeycomb structure 1 for measuring a pressure loss in a first embodiment, where (a) is a schematic perspective view and (b) is a schematic cross-sectional view.
FIG. 2 is a schematic diagram of an example of a device for evaluating a pressure loss of the honeycomb structure 1 according to the first embodiment.
FIG. 3 is an explanatory diagram for obtaining a pressure loss of a honeycomb structure 1 from an elapsed time, a flow rate of air, and a differential pressure in the first embodiment.
FIG. 4 is an explanatory diagram for obtaining a pressure loss of a honeycomb structure 1 from an elapsed time, a flow rate of air, and a differential pressure according to a second embodiment.
FIG. 5 is an explanatory diagram for obtaining a pressure loss of a honeycomb structure 1 from an elapsed time, a flow rate of air, and a differential pressure in a third embodiment.
FIG. 6 is a diagram showing a differential pressure for each of the number of measurements for different honeycomb structures 1 (A, B) in the third embodiment.
FIG. 7 is a view illustrating the condition of the supply air and the measurement environment, that is, the temperature / humidity of the air and the temperature / humidity / barometric pressure of the measurement environment, which are different from each other, using the pressure loss evaluation device of FIG. It is a figure which shows the change of the differential pressure for every elapsed time in the honeycomb structure 1 (C, D).
FIG. 8 is a schematic diagram of an apparatus for evaluating a pressure loss of a honeycomb structure 1 used for a CRT according to a sixth embodiment.
FIG. 9 is a diagram showing a differential pressure before and after correction for each input amount of carbon fine particles 15a in the sixth embodiment.
FIG. 10 is a diagram showing a flow rate and a differential pressure of different honeycomb structures 1 (E, F) measured without using the evaluation method and the evaluation device of the pressure loss of the honeycomb structure of the present invention in a comparative example. is there.
[Explanation of symbols]
1 Honeycomb structure (DPF, catalytic converter)
1a Outer skin
1b Through hole
1c Partition wall
1d, 1e end face
1f, 1g sealing material
2 cushioning material
3 Test chamber
3a Entrance side
3b Exit side
4 Filter
5 Differential pressure gauge
6 computers
6a monitor
7a, 7b, 7c, 7d air pipe
8 Absolute filter
9 Digital temperature and humidity meter
10 Differential pressure type flow meter
11 Flow control valve
12 Exhaust blower
13 Digital temperature, humidity and barometer
14 Dust injector
14a spout
15 Dust feeder
15a Carbon fine particles
16 tubes
17 dryer
18 Air compressor
A1 Inflow
A2 passing
A3 Outflow

Claims

To the honeycomb structure, an allowable range for the gas flow rate is determined and the gas is continuously supplied, and the gas inflow side and the outflow side of the honeycomb structure measured when the gas flow rate is within the allowable range within a predetermined time. A pressure loss of the honeycomb structure is determined from a pressure difference between the honeycomb structure and a pressure loss of the honeycomb structure.

To the honeycomb structure, an allowable range for the flow rate of the gas is determined and the gas is continuously supplied. When the flow rate of the gas is within the allowable range within a predetermined time, the gas inflow side and the outflow side of the honeycomb structure And measuring a pressure loss from the differential pressure when the flow rate of the gas is within the allowable range within a predetermined time continuous after the measurement of the differential pressure. Item 3. The method for evaluating pressure loss of a honeycomb structure according to Item 1.

To the honeycomb structure, an allowable range for the gas flow rate is determined and the gas is continuously supplied, the gas flow rate is within a first allowable range within a predetermined time, and the average of the gas flow rate is the predetermined value. The first allowable range is within a range having a width of at most ／ of the first allowable range within the same time as the first allowable range within a time period, and the gas in the latest short time within the predetermined time period The flow rate is within a second tolerance range narrower than the first tolerance range, and the average of the flow rates of the gas in the latest short time is the second tolerance range centered on the second tolerance range. When the pressure difference is within a range having a width of at most 2/3, the pressure difference between the gas inflow side and the gas outflow side of the honeycomb structure is measured. And when the gas flow rate is within the second allowable range, And obtaining loss, evaluation method of the pressure loss of the honeycomb structure according to claim 2.

4. The method for evaluating pressure loss of a honeycomb structure according to claim 2, wherein a variation of the pressure loss obtained repeatedly is within ± 3%. 5.

A permissible range for the flow rate of the gas is determined and supplied to the honeycomb structure, and at least 2 of the differential pressure between the gas inflow side and the outflow side of the honeycomb structure measured when the flow rate of the gas is within the permissible range. A method for evaluating pressure loss of a honeycomb structure, wherein pressure loss is obtained from an average value obtained from the above measured values.

A gas is supplied to the honeycomb structure by determining an allowable range for the flow rate of the gas, and at least 3 times the differential pressure between the gas inflow side and the outflow side of the honeycomb structure measured when the flow rate of the gas is within the allowable range. A method for evaluating pressure loss of a honeycomb structure, wherein pressure loss is obtained from a median value obtained from the above measured values.

The flow rate of the gas and the differential pressure are corrected by at least one of a temperature of the gas, a humidity of the gas, a temperature of the measurement environment, a humidity of the measurement environment, and a pressure of the measurement environment. The method for evaluating pressure loss of a honeycomb structure according to any one of claims 1 to 6.

The method for evaluating pressure loss of a honeycomb structure according to any one of claims 1 to 7, wherein fine particles are supplied to the honeycomb structure.

9. The method for evaluating pressure loss of a honeycomb structure according to claim 8, wherein the fine particles are carbon fine particles, and a charging speed of the carbon fine particles is 1 g / min or less.

A test chamber for accommodating the honeycomb structure; and a differential pressure input to a computer connected to an inlet side and an outlet side of the test chamber for detecting a differential pressure between a gas inlet side and an outlet side of the honeycomb structure. Pressure detection means, air supply means connected to the end of an air supply pipe following the test chamber to supply gas to the honeycomb structure, and gas supply means disposed in the air supply pipe to supply gas to the honeycomb structure. Flow rate detection means for detecting the flow rate of the gas and input to the computer, and flow rate control means disposed in the air supply pipe and controlling the flow rate of the gas by input and output with the computer, the computer has Stores a target flow rate of the gas to the honeycomb structure and an allowable range for the target flow rate, and detects a gas inflow side of the honeycomb structure detected when the flow rate is within the allowable range. From the differential pressure between the outlet side, the evaluation device of the pressure loss of the honeycomb structure is characterized in that so as to determine the pressure loss.

The device for evaluating pressure loss of a honeycomb structure according to claim 10, wherein a filter is provided on an inlet side of the test chamber.

The apparatus for evaluating a pressure loss of a honeycomb structure according to claim 10, further comprising: a fine particle supply unit configured to supply fine particles to the honeycomb structure on an inlet side of the test chamber.

The computer has at least one of a gas temperature detector, a gas humidity detector, a measurement environment temperature detector, a measurement environment humidity detector, and a measurement environment pressure detector. The apparatus for evaluating a pressure loss of a honeycomb structure according to any one of claims 10 to 12, wherein the flow rate and the differential pressure of the gas are corrected based on a value detected by the means.