JP2006334459A

JP2006334459A - Ceramic honeycomb filter

Info

Publication number: JP2006334459A
Application number: JP2005159263A
Authority: JP
Inventors: Hirohisa Suwabe; 博久諏訪部
Original assignee: Hitachi Metals Ltd
Current assignee: Proterial Ltd
Priority date: 2005-05-31
Filing date: 2005-05-31
Publication date: 2006-12-14

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic honeycomb filter which can stably be used for a long period of time by preventing the pressure loss from increasing caused by leaving unburnt residue of PM in the end surface 45a of flowing-in side of the opening sealing part 45 of an exhaust gas flowing-in side in the case of depositing a large amount of PM on the end surface 45a of the flowing-in side of the opening-sealing part 45 of the exhaust gas flowing-in side by continuing the state of a low temperature of the exhaust gas, in a ceramic honeycomb filter arranging the opening sealing part of an exhaust gas flowing-in side apart from the end surface of an exhaust gas flowing-in side. <P>SOLUTION: In the ceramic honeycomb filter having such a structure that the exhaust gas is allowed to pass through the partition wall of a honeycomb structure by opening-sealing the desired flow passage of the porous ceramic honeycomb structure and arranging the opening-sealing part of the exhaust gas flowing-in side apart from the end surface of the exhaust gas flowing-in side, the porosity of the partition wall is 50-80%, and the porosity of the opening-sealing part of the exhaust gas flowing-in side is smaller than that of the partition wall. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、ディーゼルエンジンから排出される粒子状物質を含む排気ガスを浄化するのに使用されるセラミックハニカムフィルタに関する。 The present invention relates to a ceramic honeycomb filter used for purifying exhaust gas containing particulate matter discharged from a diesel engine.

ディーゼルエンジンの排気ガス中には炭素質からなる煤と、高沸点炭化水素成分からなるＳＯＦ分（ＳｏｌｕｂｌｅＯｒｇａｎｉｃＦｒａｃｔｉｏｎ：可溶性有機成分）とを主成分とするＰＭ（ＰａｒｔｉｃｕｌａｔｅＭａｔｔｅｒ：粒子状物質）が含まれており、これが大気中に放出されると、人体や環境に悪影響を与える。このため、ディーゼルエンジンの排気管の途中に、ＰＭを捕集するためのフィルタを装着することが従来から行われている。図３は、自動車の排気ガス中のＰＭを捕集、浄化する、従来のハニカムフィルタの一例を示し、（ａ）は正面模式図、（ｂ）は側断面模式図である。図３（ａ）（ｂ）において、ハニカムフィルタ３０は、多孔質セラミックからなり、外周壁１と、この外周壁１の内側に各々直交する隔壁２で仕切られた多数の流路３、４を有するハニカム構造体の流路が、排気ガスの流入側端面７と流出側端面８で交互に封止部５、６で封止されている。また、ハニカム構造体の外周壁１は、金属メッシュあるいはセラミックス製のマットなどで形成された把持部材（図示せず）で使用中に動かないように把持され、金属製収納容器（図示せず）内に配置されている。 The exhaust gas of a diesel engine contains PM (Particulate Matter: particulate matter) whose main components are soot made of carbon and SOF content (soluble organic fraction) consisting of high-boiling hydrocarbon components. If it is released into the atmosphere, it will adversely affect the human body and the environment. For this reason, it has been conventionally performed to install a filter for collecting PM in the exhaust pipe of a diesel engine. FIG. 3 shows an example of a conventional honeycomb filter that collects and purifies PM in the exhaust gas of an automobile, (a) is a schematic front view, and (b) is a schematic side sectional view. 3 (a) and 3 (b), the honeycomb filter 30 is made of a porous ceramic, and includes an outer peripheral wall 1 and a large number of flow paths 3 and 4 partitioned by partition walls 2 orthogonal to the inner side of the outer peripheral wall 1, respectively. The flow path of the honeycomb structural body is sealed by the sealing portions 5 and 6 alternately at the exhaust gas inflow end surface 7 and the outflow side end surface 8. Further, the outer peripheral wall 1 of the honeycomb structure is held so as not to move during use by a holding member (not shown) formed of a metal mesh or a ceramic mat or the like, and a metal storage container (not shown). Is placed inside.

図３に示すハニカムフィルタ３０において、排気ガスの浄化は以下の通り行われる。排気ガス（点線矢印で示す）は、流入側端面７に開口している流路３から流入する。そして、排気ガス中に含まれるＰＭは、隔壁２を通過する際に捕集され、浄化された排気ガスは、流出側端面８に開口している流路４から流出、大気中に放出される。一方、隔壁２に捕集されたＰＭが多くなると、隔壁が目詰まりしてしまい圧力損失が増加してしまうので、圧力損失が増加する前に、ＰＭを燃焼除去してハニカムフィルタを再生する必要がある。しかし、通常のディーゼルエンジンの運転状態では、ＰＭが燃焼するほどの高い排気ガス温度が得られることが少ないため、例えば高比表面積材料であるアルミナに白金族金属や酸化セリウムなどの希土類酸化物を担持した酸化触媒を一体的に担持させた触媒担持型のハニカムフィルタの実用化が進められている。このような触媒担持型のハニカムフィルタを採用すれば、捕集されたＰＭの燃焼反応が触媒により促進されて、ＰＭを燃焼、除去することが可能となる。 In the honeycomb filter 30 shown in FIG. 3, the exhaust gas is purified as follows. Exhaust gas (indicated by a dotted arrow) flows in from the flow path 3 opened in the inflow side end face 7. Then, PM contained in the exhaust gas is collected when passing through the partition wall 2, and the purified exhaust gas flows out from the flow path 4 opened in the outflow side end face 8 and is released into the atmosphere. . On the other hand, if the amount of PM collected in the partition wall 2 increases, the partition wall is clogged and the pressure loss increases. Therefore, before the pressure loss increases, it is necessary to regenerate the honeycomb filter by burning and removing PM. There is. However, under normal diesel engine operating conditions, exhaust gas temperatures that are high enough to burn PM are rarely obtained. For example, alumina, which is a high specific surface area material, is mixed with rare earth oxides such as platinum group metals and cerium oxide. A catalyst-supporting honeycomb filter in which the supported oxidation catalyst is integrally supported is being put to practical use. If such a catalyst-supporting honeycomb filter is employed, the combustion reaction of the collected PM is promoted by the catalyst, and PM can be burned and removed.

ところで、このような触媒担持型のハニカムフィルタを採用したとしても、排気ガス温度の低い運転状態が続くような、渋滞の市街地を走行するような場合には、触媒が活性とならずＰＭの燃焼除去が良好に行わない不具合が発生するため、特許文献１に記載の発明では、ディーゼルエンジンの運転状態に応じて、触媒物質を担持させたフィルタ上へのＰＭの堆積量を推定した上で、フィルタの上流側に燃料を未燃のまま噴射して、前記触媒物質上で、燃料の酸化反応を促し、その反応熱によりフィルタの内部温度を前記触媒物質の活性下限温度以上に維持することによって、堆積したＰＭを燃焼させる排気浄化方法が開示されている。しかしながら、このような燃料添加によるフィルタの強制再生を行うに際し、触媒物質における燃料の酸化反応は、下流側へ向かうにつれて触媒物質との接触頻度が増すことにより活性化してくるので、このフィルタでの温度分布は、排気ガス温度とほぼ等しい流入側端面の温度から下流側に向かうにつれ反応熱により徐々に上昇し、フィルタの流入側端面は常に触媒物質の活性度は低い状態にある。このため、排気ガス温度が低い運転状態が継続した場合、触媒物質の活性度が低くなっているフィルタ流入側端面７、特に排気ガス流入側目封止部５の排気ガス流入側端面に、ＰＭが付着し易くなり、ここに付着したＰＭの堆積量が多くなることによりフィルタの流入側流路３の流入側端部が閉塞して、圧力損失が上昇する虞があった。 By the way, even when such a catalyst-carrying honeycomb filter is adopted, when the vehicle travels in a congested urban area where the exhaust gas temperature continues to be low, the catalyst becomes inactive and the PM burns. Since a problem that the removal is not performed properly occurs, the invention described in Patent Document 1 estimates the amount of PM deposited on the filter carrying the catalyst material according to the operation state of the diesel engine. By injecting fuel unburned upstream of the filter, promoting an oxidation reaction of the fuel on the catalyst material, and maintaining the internal temperature of the filter above the lower limit temperature of the catalyst material by the reaction heat An exhaust purification method for burning accumulated PM is disclosed. However, when the filter is forcibly regenerated by adding such fuel, the oxidation reaction of the fuel in the catalyst material is activated by increasing the contact frequency with the catalyst material toward the downstream side. The temperature distribution gradually increases due to the reaction heat from the temperature of the inflow side end face, which is substantially equal to the exhaust gas temperature, toward the downstream side, and the inflow side end face of the filter is always in a state of low activity of the catalyst substance. For this reason, when the operation state where the exhaust gas temperature is low continues, PM on the filter inflow side end surface 7 where the activity of the catalyst material is low, particularly the exhaust gas inflow side end surface of the exhaust gas inflow side plugging portion 5, Is likely to adhere, and the accumulated amount of PM adhering thereto increases, so that the inflow side end portion of the inflow side flow path 3 of the filter is blocked, and the pressure loss may increase.

このため、本出願人らは、特許文献２において、触媒担持型ハニカムフィルタの排気ガス流入側端部、特に排気ガス流入側目封止部の排気ガス流入側端面に、ＰＭが堆積して圧力損失が上昇するのを防ぐ目的で、図４に示すような、多孔質セラミックハニカム構造体の隔壁及び／または目封止部の少なくとも一部に触媒物質が担持されているとともに、少なくとも一つの排気ガス流入側目封止部４５が排気ガス流入側端面４７より離れて配置されていることを特徴とするセラミックハニカムフィルタ４０及び排気ガス浄化方法を開示している。このような構成のセラミックハニカムフィルタによれば、内燃機関運転中にセラミックハニカムフィルタ上へのＰＭの堆積量がある一定値以上になった際に、セラミックハニカムフィルタの温度を上昇させる目的で行うフィルタ上流への未燃の燃料及び／又は炭化水素ガス噴射時において、ＰＭが付着、堆積しやすい流入側目封止部４５の流入側端面４５ａがセラミックハニカムフィルタ内の温度の高い部位に配置されることから、当該部位に担持された触媒物質の活性度が高められるため、流入側目封止部端面４５ａでの微粒子の燃焼が容易に行われ、流入側目封止部端面４５ａへのＰＭ堆積により発生する流路の閉塞を防ぐことができる。このため、長期に亘り安定して圧力損失の増加の少ないセラミックハニカムフィルタが得られる。 For this reason, the applicants in JP-A No. 2004-86400 have a pressure in which PM accumulates on the exhaust gas inflow side end portion of the catalyst-supporting honeycomb filter, particularly on the exhaust gas inflow side end surface of the exhaust gas inflow side plugging portion. For the purpose of preventing the loss from increasing, at least one exhaust gas and a catalyst material are supported on at least a part of the partition walls and / or plugging portions of the porous ceramic honeycomb structure as shown in FIG. A ceramic honeycomb filter 40 and an exhaust gas purification method are disclosed, in which the gas inflow side plugging portion 45 is arranged away from the exhaust gas inflow side end face 47. According to the ceramic honeycomb filter having such a configuration, the filter is used for the purpose of increasing the temperature of the ceramic honeycomb filter when the amount of PM deposited on the ceramic honeycomb filter exceeds a certain value during operation of the internal combustion engine. When injecting unburned fuel and / or hydrocarbon gas upstream, the inflow side end face 45a of the inflow side plugging portion 45 where PM easily adheres and accumulates is disposed at a high temperature portion in the ceramic honeycomb filter. Therefore, the activity of the catalyst material carried on the part is increased, so that the particulates are easily burned at the inflow side plugged portion end surface 45a, and the PM deposits on the inflow side plugged portion end surface 45a. Therefore, the blockage of the flow path generated by the above can be prevented. For this reason, a ceramic honeycomb filter can be obtained which is stable over a long period of time and has little increase in pressure loss.

特開２００２−１２２０１５号公報JP 2002-122015 A 特開２００４−２５１２６６号公報JP 2004-251266 A

しかしながら、本発明者らが提案した、多孔質セラミックハニカム構造体の隔壁及び／または目封止部の少なくとも一部に触媒物質が担持されているとともに、排気ガス流入側目封止部４５が排気ガス流入側端面４７より離れて配置されていることを特徴とするセラミックハニカムフィルタ４０では、排気ガス温度の低い状態が続き、排気ガス流入側目封止部４５の流入側端面４５ａにＰＭが多量に堆積した場合は、フィルタ上流へ未燃の燃料及び／又は炭化水素ガスを噴射によるフィルタの強制再生を行ったとしても、フィルタでの温度分布は、排気ガス温度とほぼ等しい流入側端面の温度から下流側に向かうにつれ反応熱により徐々に上昇することになるので、排気ガス流入側目封止部４５より上流側の隔壁４２ｕや排気ガス流入側目封止部４５の触媒活性が不十分のため、燃え残ったＰＭが流入側端面４５ａに残留し、セラミックハニカムフィルタの圧力損失が上昇するという問題につながる場合もあった。 However, the catalyst material is supported on at least a part of the partition walls and / or plugging portions of the porous ceramic honeycomb structure proposed by the present inventors, and the exhaust gas inflow side plugging portions 45 are exhausted. In the ceramic honeycomb filter 40, which is disposed away from the gas inflow side end surface 47, the exhaust gas temperature continues to be low, and a large amount of PM is present on the inflow side end surface 45 a of the exhaust gas inflow side plugging portion 45. When the filter is forcedly regenerated by injecting unburned fuel and / or hydrocarbon gas upstream of the filter, the temperature distribution in the filter is the temperature of the inflow side end face that is substantially equal to the exhaust gas temperature. Since it gradually rises due to the reaction heat as it goes from the downstream side to the downstream side, the partition wall 42u upstream of the exhaust gas inflow side plugging portion 45 and the exhaust gas inflow side plugging Because the catalytic activity of the Department 45 is insufficient burning remaining PM remains in the inflow side end face 45a, the pressure loss of the ceramic honeycomb filter was also lead to a problem that rises.

本発明は、上記問題に鑑みてなされたもので、排気ガス流入側目封止部が排気ガス流入側端面から離れて配置されているセラミックハニカムフィルタにおいて、排気ガス温度の低い状態が続き、排気ガス流入側目封止部４５の流入側端面４５ａにＰＭが多量に堆積した場合に、排気ガス流入側目封止部４５の流入側端面４５ａに燃え残りのＰＭが残留して、圧力損失が上昇するのを防止し、長期に亘り安定して使用できるセラミックハニカムフィルタを提供することにある。 The present invention has been made in view of the above problems. In the ceramic honeycomb filter in which the exhaust gas inflow side plugging portion is arranged away from the end surface of the exhaust gas inflow side, the exhaust gas temperature is continuously low, When a large amount of PM accumulates on the inflow side end surface 45a of the gas inflow side plugging portion 45, unburned PM remains on the inflow side end surface 45a of the exhaust gas inflow side plugging portion 45, resulting in pressure loss. An object of the present invention is to provide a ceramic honeycomb filter that can be prevented from rising and can be used stably over a long period of time.

本発明者らは、排気ガス流入側目封止部４５が排気ガス流入側端面４７より離れて配置されているセラミックハニカムフィルタ４０において発生する上記問題に対して、鋭意検討を行い、本発明に想到した。 The inventors of the present invention have made intensive studies on the above-mentioned problem that occurs in the ceramic honeycomb filter 40 in which the exhaust gas inflow side plugging portion 45 is arranged away from the exhaust gas inflow side end face 47, and the present invention has been made. I thought.

本発明のセラミックハニカムフィルタは、多孔質セラミックハニカム構造体の所望の流路を目封止することによりハニカム構造体の隔壁に排気ガスを通過させる構造を有し、排気ガス流入側目封止部が排気ガス流入側端面から離れて配置されているセラミックハニカムフィルタにおいて、前記隔壁の気孔率が５０〜８０％、前記排気ガス流入側目封止部の気孔率が前記隔壁の気孔率より小さいことを特徴とする。 The ceramic honeycomb filter of the present invention has a structure that allows exhaust gas to pass through the partition walls of the honeycomb structure by plugging a desired flow path of the porous ceramic honeycomb structure, and the exhaust gas inflow side plugged portion In the ceramic honeycomb filter, which is disposed away from the exhaust gas inflow side end face, the partition wall has a porosity of 50 to 80%, and the exhaust gas inflow side plugged portion has a porosity smaller than the partition wall porosity. It is characterized by.

本発明のセラミックハニカムフィルタにおいて、前記排気ガス流入側目封止部の気孔率が前記隔壁の気孔率の０．５〜０．９倍であることが好ましい。 In the ceramic honeycomb filter of the present invention, it is preferable that the porosity of the exhaust gas inflow side plugged portion is 0.5 to 0.9 times the porosity of the partition wall.

本発明のセラミックハニカムフィルタにおいて、排気ガス流出側目封止部の気孔率が前記隔壁の気孔率より大きいことが好ましい。また、前記排気ガス流出側目封止部の気孔率が９０％以下であり、かつ前記隔壁の気孔率の１．１〜１．５倍であることが好ましい。 In the ceramic honeycomb filter of the present invention, it is preferable that the porosity of the exhaust gas outflow side plugged portion is larger than the porosity of the partition wall. Further, the porosity of the exhaust gas outlet side plugged portion is preferably 90% or less and 1.1 to 1.5 times the porosity of the partition wall.

（作用効果）
本発明のセラミックハニカムフィルタ１０の作用効果について、図１の模式断面図を用いて説明する。本発明のセラミックハニカムフィルタ１０は、多孔質セラミックハニカム構造体の所望の流路を目封止することによりハニカム構造体の隔壁に排気ガスを通過させる構造を有し、排気ガス流入側目封止部１５が排気ガス流入側端面１７から離れて配置されているセラミックハニカムフィルタにおいて、前記隔壁の気孔率が５０〜８０％、前記排気ガス流入側目封止部１５の気孔率を前記隔壁の気孔率より小さくしている。 (Function and effect)
The effects of the ceramic honeycomb filter 10 of the present invention will be described with reference to the schematic cross-sectional view of FIG. The ceramic honeycomb filter 10 of the present invention has a structure that allows exhaust gas to pass through the partition walls of the honeycomb structure by plugging a desired flow path of the porous ceramic honeycomb structure, and is plugged on the exhaust gas inflow side. In the ceramic honeycomb filter in which the portion 15 is disposed away from the exhaust gas inflow side end face 17, the partition wall has a porosity of 50 to 80%, and the exhaust gas inflow side plugging portion 15 has a porosity of It is smaller than the rate.

本発明のセラミックハニカムフィルタ１０は、流入側目封止部１５の気孔率を隔壁に比べて小さくしていることから、流入側目封止部１５の気孔率が隔壁と同じ、或いは隔壁に比べて大きい場合に比べて、排気ガスは流入側目封止部１５内を通過し難くなるため、排気ガス温度の低い運転状態が続いた場合であっても、流入側目封止部１５の流入側端面１５ａへのＰＭ堆積量を減少させることができる。フィルタ上流への未燃燃料及び／又は炭化水素ガス噴射によるフィルタの強制再生を行うに際し、触媒活性度が低い状態になりやすい流入側目封止部１５の流入側端面１５ａでのＰＭ堆積量が減少しているため、堆積したＰＭを良好に燃焼させることができ、燃え残ったＰＭによるセラミックハニカムフィルタ１０の圧力損失が上昇するのを防ぐことができる。ここで、前記隔壁の気孔率を５０〜８０％とするのは、隔壁の気孔率が５０％未満であると、ハニカムフィルタの圧力損失が上昇し、エンジンの出力低下につながるからであり、隔壁の気孔率が８０％を超えると、隔壁の強度が低下するため、使用時の熱衝撃や機械的振動により破損することがあるからであり、捕集効率も低下するからである。 In the ceramic honeycomb filter 10 of the present invention, since the porosity of the inflow side plugged portion 15 is smaller than that of the partition wall, the porosity of the inflow side plugged portion 15 is the same as that of the partition wall or compared with that of the partition wall. The exhaust gas is less likely to pass through the inflow side plugging portion 15 than in the case where the exhaust gas temperature is large. The amount of PM deposited on the side end face 15a can be reduced. When the filter is forcibly regenerated by injecting unburned fuel and / or hydrocarbon gas upstream of the filter, the amount of PM deposited on the inflow side end face 15a of the inflow side plugging portion 15 that tends to be in a low catalyst activity level is low. Since it decreases, accumulated PM can be burned well, and it can prevent that the pressure loss of the ceramic honeycomb filter 10 by the unburned PM rises. Here, the porosity of the partition wall is set to 50 to 80% because when the partition wall porosity is less than 50%, the pressure loss of the honeycomb filter increases and the output of the engine decreases. This is because if the porosity exceeds 80%, the strength of the partition walls is reduced, so that it may be damaged by thermal shock or mechanical vibration during use, and the collection efficiency is also reduced.

本発明のセラミックハニカムフィルタにおいて、前記排気ガス流入側目封止部の気孔率が前記隔壁の気孔率の０．５〜０．９倍であることが好ましいのは、排気ガス温度が低い状態が続いた場合であっても、流入側目封止部１５の流入側端面１５ａへのＰＭ堆積量を確実に減少させるのと共に、目封止部１５と隔壁間の耐熱衝撃強度を確保するためである。すなわち、前記排気ガス流入側目封止部１５の気孔率が前記隔壁の気孔率の０．５倍未満である場合、流入側目封止部と隔壁との気孔率の差が大きいため、両者の熱容量の違いが大きくなって、フィルタ上流への未燃燃料及び／又は炭化水素ガス噴射によるフィルタの強制再生を行う際の熱衝撃が加わった場合、両者の間にキレツが発生することもあるからである。また、前記排気ガス流入側目封止部１５の気孔率が前記隔壁の気孔率の０．９倍を越えると、排気ガス温度の低い状態が続いた場合の、流入側目封止部１５の流入側端面１５ａへのＰＭ堆積量を減少させる効果が小さく、セラミックハニカムフィルタの圧力損失上昇を低減する効果が小さい場合もあるからである。前記排気ガス流入側目封止部の気孔率のより好ましい範囲は、前記隔壁の気孔率の０．６〜０．８倍である。 In the ceramic honeycomb filter of the present invention, the porosity of the exhaust gas inflow side plugged portion is preferably 0.5 to 0.9 times the porosity of the partition wall because the exhaust gas temperature is low. Even in the case where it continues, the amount of PM deposited on the inflow side end face 15a of the inflow side plugged portion 15 can be surely reduced and the thermal shock strength between the plugged portion 15 and the partition wall can be secured. is there. That is, when the porosity of the exhaust gas inflow side plugged portion 15 is less than 0.5 times the porosity of the partition wall, the difference in porosity between the inflow side plugged portion and the partition wall is large. When the difference in the heat capacity of the filter increases and thermal shock is applied when the filter is forcibly regenerated by injecting unburned fuel and / or hydrocarbon gas upstream of the filter, there may be a crease between the two. Because. Further, when the porosity of the exhaust gas inflow side plugging portion 15 exceeds 0.9 times the porosity of the partition wall, the inflow side plugging portion 15 in the case where the exhaust gas temperature continues to be low. This is because the effect of reducing the amount of PM deposited on the inflow side end face 15a is small, and the effect of reducing the increase in pressure loss of the ceramic honeycomb filter may be small. A more preferable range of the porosity of the exhaust gas inflow side plugged portion is 0.6 to 0.8 times the porosity of the partition wall.

本発明のセラミックハニカムフィルタにおいて、排気ガス流出側目封止部の気孔率が前記隔壁の気孔率より大きいことが好ましいのは、排気ガス流出側封止部１６内を排気ガスが通過しやすくなるため、セラミックハニカムフィルタの圧力損失をより低減することができるからである。また、前記排気ガス流出側目封止部の気孔率が９０％以下であり、かつ前記隔壁の気孔率の１．１〜１．５倍であることが好ましいのは、排気ガス流出側封止部内を排気ガスが確実に通過しやすくなるためであり、セラミックハニカムフィルタの圧力損失をより低減することができるからである。前記排気ガス流出側目封止部の気孔率が９０％以下とするのは、気孔率が９０％を越えると、排気ガス流出側封止部自体の強度が小さくなって破損しやすくなることもあるからであり、前記排気ガス流出側目封止部の気孔率が前記隔壁の気孔率の１．１倍未満であると、流出側目封止部１６での圧力損失低減効果が得られない場合もあるからであり、１．５倍を越えると排気ガス流出側封止部自体の強度が小さくなって破損しやすくなることもあるからである。前記排気ガス流入側目封止部の気孔率のより好ましい範囲は、前記隔壁の気孔率の１．２〜１．４倍である。 In the ceramic honeycomb filter of the present invention, it is preferable that the porosity of the exhaust gas outflow side plugging portion is larger than the porosity of the partition wall so that the exhaust gas easily passes through the exhaust gas outflow side sealing portion 16. This is because the pressure loss of the ceramic honeycomb filter can be further reduced. The exhaust gas outlet side plugging portion preferably has a porosity of 90% or less and 1.1 to 1.5 times the porosity of the partition wall. This is because the exhaust gas can easily surely pass through the inside, and the pressure loss of the ceramic honeycomb filter can be further reduced. The porosity of the exhaust gas outlet side plugged portion is set to 90% or less. When the porosity exceeds 90%, the strength of the exhaust gas outlet side sealed portion itself may be reduced and easily damaged. This is because if the porosity of the exhaust gas outlet side plugged portion is less than 1.1 times the porosity of the partition wall, the effect of reducing pressure loss at the outlet side plugged portion 16 cannot be obtained. This is because the strength of the exhaust gas outflow side sealing part itself may be reduced and may be easily damaged when the ratio exceeds 1.5 times. A more preferable range of the porosity of the exhaust gas inflow side plugged portion is 1.2 to 1.4 times the porosity of the partition wall.

本発明のセラミックハニカムフィルタにおいて、図１に示すように排気ガス流入側目封止部１５すべてが、セラミックハニカムフィルタの排気ガス流入側端面１７から離れている必要はなく、本発明の効果が得られる程度に配置されていれば良い。具体的には少なくとも７０％以上の排気ガス流入側目封止部１５が、排気ガス流入側端面１７より離れていれば、ＰＭの排気ガス流入側端部への堆積による圧力損失上昇を防ぐ効果が大きくなる。より好ましくは９０％以上である。更に好ましくは９５％以上である。 In the ceramic honeycomb filter of the present invention, as shown in FIG. 1, it is not necessary that all the exhaust gas inflow side plugging portions 15 are separated from the exhaust gas inflow side end face 17 of the ceramic honeycomb filter, and the effect of the present invention is obtained. As long as it is arranged as much as possible. Specifically, if at least 70% or more of the exhaust gas inflow side plugging portion 15 is separated from the end surface 17 of the exhaust gas inflow side, an effect of preventing an increase in pressure loss due to accumulation of PM on the end side of the exhaust gas inflow side. Becomes larger. More preferably, it is 90% or more. More preferably, it is 95% or more.

また、本発明のセラミックハニカムフィルタにおいて、排気ガス流入側端面より離れて配置される排気ガス流入側目封止部１５の配置位置は、セラミックハニカムフィルタの所望の圧力損失やＰＭ捕集率が得られるように適宜選択すれば良いが、前記排気ガス流入側端面１５ａが、セラミックハニカムフィルタの排気ガス流入側端面１７から、該セラミックハニカムフィルタ全長の０．７倍以下の長さの区間に配置されていることが好ましい。排気ガス流入側端面１５ａの位置を、流入側端面１７から該セラミックハニカムフィルタ全長の０．７倍の長さの区間を越えて配置すると、セラミックハニカムフィルタの全体の長さには制約があるため、排気ガス流入側目封止部１５より流出側の隔壁１２ｄの面積が少なくなるため、セラミックハニカムフィルタ全体の圧力損失が上昇することもあるからである。また、ハニカムフィルタ上流に未燃の燃料及び／又は炭化水素ガスを噴射した際の、排気ガス流入側目封止部１５より上流側の隔壁１２ｕでの触媒物質による温度上昇効果を確実なものとするためには、排気ガス流入側目封止部１５は流入側端面１７から３０ｍｍ以上に離れて配置されていることがさらに好ましい。また、更に好ましい流入側目封止部端面１５ａの配置区間は、セラミックハニカムフィルタ流入側端面１７から該セラミックハニカムフィルタ全長の０．２５〜０．４５倍の長さの区間である。 Further, in the ceramic honeycomb filter of the present invention, the arrangement position of the exhaust gas inflow side plugging portion 15 arranged away from the end face on the exhaust gas inflow side can obtain a desired pressure loss and PM collection rate of the ceramic honeycomb filter. The exhaust gas inflow side end surface 15a may be disposed in a section having a length not more than 0.7 times the entire length of the ceramic honeycomb filter from the exhaust gas inflow side end surface 17 of the ceramic honeycomb filter. It is preferable. If the position of the exhaust gas inflow side end face 15a is disposed beyond the section of 0.7 times the total length of the ceramic honeycomb filter from the inflow side end face 17, the overall length of the ceramic honeycomb filter is limited. This is because the pressure loss of the entire ceramic honeycomb filter may increase because the area of the partition wall 12d on the outflow side from the plugging portion 15 on the exhaust gas inflow side is reduced. In addition, when unburned fuel and / or hydrocarbon gas is injected upstream of the honeycomb filter, the temperature rise effect by the catalytic material in the partition wall 12u upstream from the exhaust gas inflow side plugging portion 15 is ensured. In order to achieve this, it is more preferable that the exhaust gas inflow side plugging portion 15 is disposed at a distance of 30 mm or more from the inflow side end surface 17. Further, a more preferable arrangement section of the inflow side plugging portion end face 15a is an area having a length 0.25 to 0.45 times as long as the entire length of the ceramic honeycomb filter from the end face 17 of the ceramic honeycomb filter inflow side.

本発明のセラミックハニカムフィルタにおいて、前記隔壁及び／または目封止部の少なくとも一部に触媒物質が担持されていることが好ましい。この理由は、内燃機関運転中にハニカムフィルタ上へのＰＭの堆積量がある一定値以上になった際のフィルタ上流への未燃の燃料及び／又は炭化水素ガス噴射時において、これら未燃の燃料及び／又は炭化水素ガスの酸化反応を促進させ、この反応熱によって、セラミックハニカムフィルタの温度を上昇させることができるからである。更に、排気ガス温度の高い高速走行などの運転状態の場合、触媒物質の作用によりＰＭを連続的に燃焼させることができ、ＰＭ堆積による圧力損失の上昇を回避することができるからである。ここで前記ハニカムフィルタに担持される触媒物質は、白金族金属を含む酸化触媒や微粒子燃焼触媒であると好ましい。尚、白金族金属を含む酸化触媒は、たとえば、Ｐｔ、Ｐｄ、Ｒｕ、Ｒｈ又はその組合せ、白金族金属酸化物等が含まれるが、アルカリ土類金属酸化物や希土類酸化物等を含んでも良い。また、白金族金属を含む触媒物質には、公知のγアルミナ等の活性アルミナからなる高比表面積材料が含まれると、白金族金属等と排気ガスとの接触面積を大きくすることができ、排気ガスの浄化効率を高めることができることから好ましい。また、微粒子燃焼触媒としては、ベース金属触媒、典型的にはランタン、セシウム、バナジウム（Ｌａ／Ｃｓ／Ｖ₂Ｏ₃）類よりなる触媒物質であると好ましい。 In the ceramic honeycomb filter of the present invention, it is preferable that a catalyst substance is supported on at least a part of the partition walls and / or plugging portions. This is because when the amount of PM accumulated on the honeycomb filter exceeds a certain value during operation of the internal combustion engine, unburned fuel and / or hydrocarbon gas is injected upstream of the filter when the unburned fuel is injected. This is because the oxidation reaction of the fuel and / or hydrocarbon gas is promoted, and the temperature of the ceramic honeycomb filter can be increased by the heat of reaction. Furthermore, in an operating state such as high-speed running with a high exhaust gas temperature, PM can be continuously burned by the action of the catalyst substance, and an increase in pressure loss due to PM deposition can be avoided. Here, the catalyst material supported on the honeycomb filter is preferably an oxidation catalyst or a particulate combustion catalyst containing a platinum group metal. The oxidation catalyst containing a platinum group metal includes, for example, Pt, Pd, Ru, Rh or a combination thereof, a platinum group metal oxide, etc., but may contain an alkaline earth metal oxide, a rare earth oxide, or the like. . In addition, when the catalyst material containing platinum group metal includes a high specific surface area material made of active alumina such as known γ alumina, the contact area between the platinum group metal and the exhaust gas can be increased, This is preferable because the gas purification efficiency can be increased. The fine particle combustion catalyst is preferably a base metal catalyst, typically a catalyst material made of lanthanum, cesium, or vanadium (La / Cs / V ₂ O ₃ ).

次に本発明のセラミックハニカムフィルタの隔壁及び目封止部を構成する材料としては、本発明が主にディーゼルエンジンの排気ガス中の微粒子を除去するために使用されるため、耐熱性に優れた材料を使用することが好ましく、コージェライト、アルミナ、ムライト、窒化珪素、炭化珪素、チタン酸アルミニウム、窒化アルミニウム及びＬＡＳからなる群から選ばれた少なくとも１種を主結晶とするセラミック材料を用いることが好ましい。中でも、コージェライトを主結晶とする材料は、安価で耐熱性、耐食性に優れ、また低熱膨張であることから最も好ましい。なお、隔壁を構成する材料と目封止部を構成する材料は異なっていても構わないが、同一であれば、目封止部と隔壁の熱膨張係数の違いによって発生する熱応力を低減できることから好ましい。 Next, as the material constituting the partition walls and plugging portions of the ceramic honeycomb filter of the present invention, the present invention is mainly used for removing fine particles in the exhaust gas of a diesel engine, and thus has excellent heat resistance. It is preferable to use a material, and it is preferable to use a ceramic material whose main crystal is at least one selected from the group consisting of cordierite, alumina, mullite, silicon nitride, silicon carbide, aluminum titanate, aluminum nitride, and LAS. preferable. Among them, a material having cordierite as the main crystal is most preferable because it is inexpensive, excellent in heat resistance and corrosion resistance, and has low thermal expansion. In addition, although the material which comprises a partition and the material which comprises a plugging part may differ, if it is the same, the thermal stress generated by the difference in the thermal expansion coefficient of a plugging part and a partition can be reduced. To preferred.

前記セラミックハニカムフィルタの隔壁の平均細孔径は１０〜４０μｍであることが好ましい。排気ガスが隔壁に形成された細孔を通過することから、平均細孔径が１０μｍ未満であると、ハニカムフィルタの圧力損失が上昇し、エンジンの出力低下につながるからであり、平均細孔径が４０μｍを越えると、隔壁の強度が低下するため、使用時の熱衝撃や機械的振動により破損することがあるからであり、捕集効率も低下するからである。 The average pore diameter of the partition walls of the ceramic honeycomb filter is preferably 10 to 40 μm. The exhaust gas passes through the pores formed in the partition walls, and if the average pore diameter is less than 10 μm, the pressure loss of the honeycomb filter increases, leading to a decrease in engine output. The average pore diameter is 40 μm. This is because the strength of the partition walls will be reduced if it exceeds the range, it may be damaged by thermal shock or mechanical vibration during use, and the collection efficiency will also decrease.

本発明に係るセラミックハニカムフィルタの隔壁の厚さは０．１〜０．５ｍｍが好ましく、隔壁のピッチは１．０〜３．０ｍｍが好ましい。隔壁厚が０．１ｍｍ未満では、隔壁が細孔を有する高気孔率の多孔質体であることからハニカム構造体の強度が低下し、好ましくない。一方、隔壁厚が０．５ｍｍを超えると、如何に隔壁が高気孔率であっても、排気ガスに対する隔壁の通気抵抗が大きくなるため、セラミックハニカムフィルタの圧力損失が大きくなるからである。より好ましい隔壁厚さは、０．２〜０．４ｍｍである。また、隔壁のピッチが１．３ｍｍ未満であると、ハニカム構造体の流路の開口面積が小さくなることから、セラミックハニカムフィルタの流路を排気ガスが出入りする際の圧力損失が大きくなるため、好ましくない。一方、隔壁のピッチが３．０ｍｍを超えると、セラミックハニカムフィルタの単位体積当たりの表面積が小さくなることから、圧力損失が大きくなることも有るからである。より好ましい隔壁のピッチは１．２〜２．０ｍｍである。 In the ceramic honeycomb filter according to the present invention, the partition wall thickness is preferably 0.1 to 0.5 mm, and the partition wall pitch is preferably 1.0 to 3.0 mm. When the partition wall thickness is less than 0.1 mm, the partition wall is a porous body having a high porosity and thus the strength of the honeycomb structure is lowered, which is not preferable. On the other hand, when the partition wall thickness exceeds 0.5 mm, no matter how high the partition wall has a high porosity, the ventilation resistance of the partition wall to the exhaust gas increases, and the pressure loss of the ceramic honeycomb filter increases. A more preferable partition wall thickness is 0.2 to 0.4 mm. In addition, if the partition wall pitch is less than 1.3 mm, the opening area of the flow path of the honeycomb structure is reduced, so that the pressure loss when exhaust gas enters and exits the flow path of the ceramic honeycomb filter increases. It is not preferable. On the other hand, if the partition pitch exceeds 3.0 mm, the surface area per unit volume of the ceramic honeycomb filter is reduced, and the pressure loss may be increased. A more preferable partition pitch is 1.2 to 2.0 mm.

本発明のセラミックハニカムフィルタは、排気ガス流入側目封止部１５がセラミックハニカムフィルタ内の温度の高い部位に配置されれば微粒子の燃焼が容易に行われ、微粒子の堆積による圧力損失の上昇が起こりにくくなることを考慮すると、排気ガス流入側目封止部１５は、図２（１）に示すように排気ガス流入側目封止部端面１５ａが流入側端面１７から同一の位置に配置されなくても良く、また、図２（２）に示すように、排気ガス流入側目封止部１５及び流出側目封止部１６の長さは全て同一でなくても良い。また、本発明の効果が得られるのであれば、排気ガス流出側目封止部１６は、同一の長さでなくても良く、同一の位置に配置されなくても良い。 In the ceramic honeycomb filter of the present invention, if the exhaust gas inflow side plugging portion 15 is arranged at a high temperature portion in the ceramic honeycomb filter, the particulates are easily burned, and the pressure loss increases due to the deposition of the particulates. Considering that the exhaust gas inflow side plugging portion 15 is less likely to occur, the exhaust gas inflow side plugging portion end surface 15a is arranged at the same position from the inflow side end surface 17 as shown in FIG. The lengths of the exhaust gas inflow side plugging portion 15 and the outflow side plugging portion 16 do not have to be the same as shown in FIG. Moreover, as long as the effect of the present invention is obtained, the exhaust gas outflow side plugging portions 16 may not have the same length and may not be arranged at the same position.

以上詳細に説明したように、本発明によれば、多孔質セラミックハニカム構造体の所望の流路を目封止することによりハニカム構造体の隔壁に排気ガスを通過させる構造を有し、排気ガス流入側目封止部が排気ガス流入側端面から離れて配置されているセラミックハニカムフィルタにおいて、前記隔壁の気孔率を５０〜８０％、前記排気ガス流入側目封止部の気孔率を前記隔壁の気孔率より小さくしていることから、排気ガスが流入側目封止部内を通過しにくく、排気ガス温度の低い運転状態が続いた場合であっても、流入側目封止部の流入側端面へのＰＭ堆積を減少させることができるため、フィルタ上流への未燃燃料及び／又は炭化水素ガス噴射によるフィルタの強制再生を行うに際し、触媒活性度が低い状態になりやすい流入側目封止部１５の流入側端面１５ａであっても、堆積したＰＭを良好に燃焼させることができ、燃え残ったＰＭによるセラミックハニカムフィルタの圧力損失の上昇を防ぐという効果が得られる。 As described above in detail, according to the present invention, the exhaust gas is passed through the partition walls of the honeycomb structure by plugging a desired flow path of the porous ceramic honeycomb structure. In the ceramic honeycomb filter in which the inflow side plugging portion is arranged away from the exhaust gas inflow side end surface, the partition wall has a porosity of 50 to 80%, and the exhaust gas inflow side plugging portion has a porosity of the partition wall. Therefore, even if the exhaust gas is less likely to pass through the inflow side plugged portion and the operation state at a low exhaust gas temperature continues, the inflow side of the inflow side plugged portion Since PM accumulation on the end face can be reduced, inflow side plugging that tends to result in low catalyst activity when forcibly regenerating the filter by injecting unburned fuel and / or hydrocarbon gas upstream of the filter Even inlet-side end 15a of 15, the deposited PM can be satisfactorily combusted, effect that prevents an increase in pressure loss of the ceramic honeycomb filter according burning remaining PM.

本発明の、多孔質セラミックハニカム構造体の所望の流路を目封止することによりハニカム構造体の隔壁に排気ガスを通過させる構造を有し、流入側目封止部１５がセラミックハニカムフィルタの排気ガス流入側端面１７から離れて配置されており、前記隔壁の気孔率が５０〜８０％、前記排気ガス流入側目封止部１５の気孔率が前記隔壁の気孔率より小さいセラミックハニカムフィルタ１０の製造方法一例を図５を用いて説明する。セラミックス原料粉末に、バインダーなどの成形助剤と造孔剤を添加し、規定量の水を注入してさらに十分な混合を行い、押出成形可能な坏土を調整し、押出成形用金型を用いて押出成形し、外周壁と、この外周壁の内周側で隔壁により囲まれた断面が四角形状の流路を有するハニカム構造を有する成形体を作製し、乾燥した。その後、焼成を行い、外径２６７ｍｍ、全長Ｌ３００ｍｍ、隔壁の厚さ０．３ｍｍ、隔壁のピッチ１．５ｍｍ、隔壁の気孔率５０〜８０％の多孔質セラミックハニカム構造体を準備する（図５（１））。このとき、気孔率５０〜８０％が得られるよう、セラミックス原料粉末の粒径や造孔剤の添加量を適宜調整する。その後、このハニカム構造体１１の流路１４内の所定位置に、流路幅より小さい外径を有する管状部材６１を挿入し、この管状部材からセラミック原料粉末、バインダー、水、必要に応じて分散材等の助剤等からなる流入側目封止部用の目封止材スラリーを流路内に所定量注入する（図５（２））。注入された目封止材スラリー中の水が多孔質隔壁中に毛細管現象で吸水されることにより、目封止材スラリーは固化して、排気ガス流入側端面から離れた位置に排気ガス流入側目封止部１５を形成する（図５（３））。このとき、流入側封止部１５の流路方向長さは注入量を調整することにより調整することができる。次いで、排気ガス流出側端面に樹脂製フィルム６５を貼り付け、排気ガス流入側目封止部１５を形成していない流路１３のフィルムをレーザ光などにより穿孔して、開口し（図５（４））、セラミック原料粉末、バインダー、造孔剤、水、必要に応じて分散材等の助剤等からなる流出側目封止部用の目封止材スラリーを開口部から浸入させて（図５（５））、排気ガス流出側目封止部１６を形成した後、フィルム６５を剥がして乾燥、焼成を行い、目封止部と隔壁を一体化させてセラミックハニカムフィルタ１０を得る。 The porous ceramic honeycomb structure of the present invention has a structure that allows exhaust gas to pass through the partition walls of the honeycomb structure by plugging a desired flow path of the porous ceramic honeycomb structure. The ceramic honeycomb filter 10 is disposed away from the end face 17 on the exhaust gas inflow side, the porosity of the partition wall is 50 to 80%, and the porosity of the exhaust gas inflow side plugging portion 15 is smaller than the porosity of the partition wall. An example of the manufacturing method will be described with reference to FIG. Add a molding aid such as a binder and a pore-forming agent to the ceramic raw material powder, inject a specified amount of water, mix thoroughly, adjust the extrudable clay, and prepare an extrusion mold. A molded body having a honeycomb structure having a channel having a square cross section surrounded by a partition wall on the inner peripheral side of the outer peripheral wall and the outer peripheral wall was produced and dried. Thereafter, firing is performed to prepare a porous ceramic honeycomb structure having an outer diameter of 267 mm, an overall length of L300 mm, a partition wall thickness of 0.3 mm, a partition wall pitch of 1.5 mm, and a partition wall porosity of 50 to 80% (FIG. 5 ( 1)). At this time, the particle size of the ceramic raw material powder and the amount of pore-forming agent added are appropriately adjusted so that a porosity of 50 to 80% is obtained. Thereafter, a tubular member 61 having an outer diameter smaller than the channel width is inserted into a predetermined position in the channel 14 of the honeycomb structure 11, and ceramic raw material powder, binder, water, and dispersed as necessary from the tubular member A predetermined amount of a plugging material slurry for the inflow side plugging portion made of an auxiliary material such as a material is injected into the flow path (FIG. 5B). The water in the injected plugging material slurry is absorbed into the porous partition wall by capillary action, so that the plugging material slurry is solidified, and the exhaust gas inflow side is located away from the exhaust gas inflow side end surface. A plugging portion 15 is formed (FIG. 5 (3)). At this time, the flow direction length of the inflow side sealing part 15 can be adjusted by adjusting the injection amount. Next, a resin film 65 is attached to the exhaust gas outflow side end face, and the film of the flow path 13 in which the exhaust gas inflow side plugging portion 15 is not formed is perforated with a laser beam or the like (FIG. 5 ( 4)) A plugging material slurry for the outflow side plugging portion made of ceramic raw material powder, binder, pore-forming agent, water, and auxiliary agent such as a dispersing agent as required is infiltrated from the opening ( 5 (5)), after forming the exhaust gas outlet side plugged portion 16, the film 65 is peeled off, dried and fired, and the plugged portion and the partition wall are integrated to obtain the ceramic honeycomb filter 10.

ここで、排気ガス流入側目封止部１５の気孔率を隔壁の気孔率より小さくするには、排気ガス流入側目封止部１５を形成するため目封止材スラリ−を作成する際に、造孔剤を添加しない、或いは造孔剤の添加量を、隔壁を形成するための坏土より少なくする等の方法により得ることができる。また、排気ガス流出側目封止部１６の気孔率を隔壁の気孔率より大きくするには、排気ガス流出側目封止部１６を形成するため目封止材スラリ−を作成する際に、造孔剤の添加量を、隔壁を形成するための坏土より多くする等の方法により得ることができる。 Here, in order to make the porosity of the exhaust gas inflow side plugging portion 15 smaller than the porosity of the partition wall, when forming the plugging material slurry to form the exhaust gas inflow side plugging portion 15. The pore-forming agent is not added, or the amount of pore-forming agent added is less than that of the clay for forming the partition walls. Further, in order to make the porosity of the exhaust gas outflow side plugging portion 16 larger than the porosity of the partition wall, when creating the plugging material slurry to form the exhaust gas outflow side plugging portion 16, It can be obtained by a method such as increasing the amount of pore-forming agent added to the clay for forming the partition walls.

以下、発明の実施の形態を詳細に説明する。
（実施例） Hereinafter, embodiments of the present invention will be described in detail.
(Example)

図１は本発明の実施例１に係るハニカムフィルタの断面模式図である。図１のセラミックハニカムフィルタ１０は、外周壁の内側に隔壁で仕切られた多数の四角形の流路を有し、この流路は流入側目封止部１５、及び流出側目封止部１６で目封止されており、流入側目封止部１５は流入側端面１７から離れた流路内に配置され、隔壁の気孔率は５０〜８０％、流入側目封止部１５の気孔率は隔壁の気孔率より小さくなるように形成されている。
本実施例におけるセラミックハニカムフィルタは、以下の製造工程で製造した。カオリン、タルク、シリカ、アルミナ、水酸化アルミニウムの粉末を調整して、質量比で、ＳｉＯ₂：４８〜５２％、Ａｌ₂Ｏ₃：３３〜３７％、ＭｇＯ：１２〜１５％を含むコーディエライト生成原料粉末とする。本実施例ではＳｉＯ₂：５０％、Ａｌ₂Ｏ₃：３５％、ＭｇＯ：１５％に調整した。これにメチルセルロース、ヒドロキシプロピルメチルセルロース等のバインダー、潤滑材、造孔剤として有機発泡剤を添加し、乾式で十分混練した後、規定量の水を添加、十分な混練を行って可塑化したセラミック坏土を作成した。次に、押出し成形用金型を用いて坏土を押出し成形し、切断して、ハニカム構造を有する成形体とした。次にこの成形体を、乾燥、焼成し、隔壁の厚さ０．３ｍｍ、気孔率６５％、平均細孔径２０μｍ、隔壁ピッチ１．５ｍｍ、外径が２６７ｍｍ、全長が３０５ｍｍのコーディエライト質セラミックハニカム構造体を得た。 FIG. 1 is a schematic cross-sectional view of a honeycomb filter according to Example 1 of the present invention. The ceramic honeycomb filter 10 of FIG. 1 has a large number of rectangular channels partitioned by partition walls on the inner side of the outer peripheral wall, and these channels are formed by an inflow side plugging portion 15 and an outflow side plugging portion 16. The inflow side plugging portion 15 is arranged in a flow path separated from the inflow side end surface 17, the porosity of the partition wall is 50 to 80%, and the porosity of the inflow side plugging portion 15 is It is formed to be smaller than the porosity of the partition wall.
The ceramic honeycomb filter in this example was manufactured by the following manufacturing process. A cordier containing powders of kaolin, talc, silica, alumina and aluminum hydroxide and containing SiO ₂ : 48-52%, Al ₂ O ₃ : 33-37%, MgO: 12-15% by mass ratio Use light-generating raw material powder. In this example, the SiO ₂ ratio was adjusted to 50%, the Al ₂ O ₃ ratio to 35%, and the MgO ratio to 15%. To this was added an organic foaming agent as a binder such as methylcellulose and hydroxypropylmethylcellulose, a lubricant, and a pore-forming agent. Created soil. Next, the kneaded material was extruded using an extrusion molding die and cut to obtain a formed body having a honeycomb structure. Next, the compact is dried and fired, and cordierite ceramic having a partition wall thickness of 0.3 mm, a porosity of 65%, an average pore diameter of 20 μm, a partition wall pitch of 1.5 mm, an outer diameter of 267 mm, and a total length of 305 mm. A honeycomb structure was obtained.

次に、図５（２）に示すように、目封止材スラリー保管タンク（図示せず）から流入側目封止部用の目封止材スラリーを管状部材６１に供給するチューブ６３、バルブ６４から構成される目封止材スラリー料供給装置に、セラミックハニカム構造体１１を流路方向が略重力方向に一致するように載置した。目封止材料の供給に使用する管状部材６１は、ステンレス鋼製で外径φ１．１ｍｍ、内径φ０．８ｍｍの断面円形のものを用いた。また、目封止材スラリーは、セラミック原料粉末として、タルク、カオリン、シリカ、アルミナ、水酸化アルミニウムのコーディエライト化原料粉末Ａを、質量比で、ＳｉＯ₂：５０％、Ａｌ₂Ｏ₃：３５％、ＭｇＯ：１５％となるよう調整して用い、セラミック原料粉末に対し、有機発泡剤、メチルセルロースを加えて、乾式混合した後、イオン交換水、分散剤としてポリカルボン酸系界面活性剤を加えて湿式混合して作製した。ここで、流入側目封止部の気孔率が表１に示すものが得られるよう、有機発泡剤の添加量を調整して（添加量０含む）、試験ＮＯ.１〜６用の目封止材スラリーに調整した。 Next, as shown in FIG. 5 (2), a tube 63 and a valve for supplying the plugging material slurry for the inflow side plugging portion from the plugging material slurry storage tank (not shown) to the tubular member 61. The ceramic honeycomb structure 11 was placed on a plugging material slurry supply apparatus composed of 64 so that the flow path direction substantially coincided with the gravity direction. The tubular member 61 used for supplying the plugging material was made of stainless steel and had a circular cross section with an outer diameter of φ1.1 mm and an inner diameter of φ0.8 mm. Further, the plugging material slurry is a cordierite forming raw material powder A of talc, kaolin, silica, alumina, and aluminum hydroxide as a ceramic raw material powder in terms of mass ratio, SiO ₂ : 50%, Al ₂ O ₃ : 35%, MgO: Adjusted to 15%, and after adding organic foaming agent and methylcellulose to the ceramic raw material powder and dry mixing, ion-exchanged water, polycarboxylic acid surfactant as dispersant In addition, it was prepared by wet mixing. Here, the addition amount of the organic foaming agent was adjusted (including the addition amount of 0) so that the porosity of the inflow side plugged portion shown in Table 1 was obtained, and the plugs for test Nos. 1 to 6 were used. It adjusted to the stopping material slurry.

次に、管状部材６１を目封止する流路内へ、セラミックハニカム構造体１１の端面１７から１２０ｍｍの位置に挿入し、所定量の目封止材スラリーを管状部材から注入し、目封止スラリー中の水を多孔質隔壁中に吸水させることにより、目封止材を固化させた。その他の流路についても同様に、目封止を行った後、乾燥を行った。その後、排気ガス流出側端面に樹脂製フィルム６５を貼り付け、所定の流路に相当する箇所を穿孔して、排気ガス流出側端面１８からコーディエライト化原料及び有機発泡剤からなる目封止材スラリーを流入させて排気ガス流出側目封止部を形成した。その後、大気中で１４００℃に加熱して、目封止材の焼成を行うと共に、目封止部と隔壁を一体化させて、試験ＮＯ．１〜６のセラミックハニカムフィルタを作製した。 Next, the tubular member 61 is inserted into the flow path for plugging the tubular member 61 at a position 120 mm from the end face 17 of the ceramic honeycomb structure 11, and a predetermined amount of the plugging material slurry is injected from the tubular member, and plugged. The plugging material was solidified by absorbing water in the slurry into the porous partition walls. Similarly, the other channels were plugged and then dried. Thereafter, a resin film 65 is attached to the exhaust gas outflow side end face, a portion corresponding to a predetermined flow path is perforated, and the exhaust gas outflow side end face 18 is plugged with a cordierite forming raw material and an organic foaming agent. The material slurry was introduced to form an exhaust gas outlet side plugged portion. Thereafter, the plugging material is baked by heating to 1400 ° C. in the atmosphere, and the plugging portion and the partition wall are integrated. 1 to 6 ceramic honeycomb filters were produced.

試験ＮＯ．１〜６のセラミックハニカムフィルタに対して、Ｐｔ、酸化セリウム、及び活性アルミナからなる触媒物質を隔壁表面及び隔壁中の細孔内部、更には目封止部表面及び目封止部中の細孔内部に担持させた。担持量はＰｔ量で２ｇ／Ｌ（ハニカムフィルタ容積１Ｌに対して２ｇ担持の意味）とした。 Test NO. For the ceramic honeycomb filters 1 to 6, a catalyst material composed of Pt, cerium oxide, and activated alumina is applied to the partition wall surface and inside the pores in the partition wall, and further to the plugging portion surface and the pores in the plugging portion. It was carried inside. The supported amount was 2 g / L in terms of Pt amount (meaning 2 g supported per 1 L of honeycomb filter volume).

上記のように作製した試験ＮＯ．１〜６のセラミックハニカムフィルタを圧力損失試験装置（図示せず）に設置し、空気流量７．５Ｎｍ³／ｍｉｎの条件で空気を流入し、流入側端面と流出側端面の差圧を測定し、各セラミックハニカムフィルタの初期圧力損失を評価した。更に、試験ＮＯ．１〜６のセラミックハニカムフィルタを、ディーゼルエンジンの排気管に配置し、市街地走行を模したパターン走行条件で耐久試験を行った。この際、排気ガス温度が触媒物質の活性下限温度を下まわるような運転状態が続くような場合を発生させ、ＰＭがフィルタ上に多量に堆積するような条件を作り出した上で、この運転状態に応じて、触媒物質を担持させたセラミックハニカムフィルタ上へのＰＭの堆積量を推定し、堆積量が一定値以上なったと判断された時点で、フィルタの上流側に燃料を未燃のまま噴射して、フィルタの強制再生を繰り返す耐久試験を行った。その後、耐久試験後のハニカムフィルタの圧力損失を初期圧力損失と同様に測定し、初期圧力損失と比較して、圧力損失比：(試験後の圧力損失)／（初期圧力損失）を算出し、表１に示した。 Test NO. Produced as described above. 1 to 6 ceramic honeycomb filters are installed in a pressure loss test device (not shown), air is introduced under the condition of an air flow rate of 7.5 Nm ³ / min, and the differential pressure between the inflow side end surface and the outflow side end surface is measured. The initial pressure loss of each ceramic honeycomb filter was evaluated. Furthermore, test NO. The ceramic honeycomb filters 1 to 6 were arranged in an exhaust pipe of a diesel engine, and an endurance test was performed under pattern running conditions simulating urban driving. At this time, an operation state in which the exhaust gas temperature falls below the lower activation limit temperature of the catalyst substance is generated, and conditions are set such that a large amount of PM is deposited on the filter. Accordingly, the amount of PM deposited on the ceramic honeycomb filter carrying the catalyst substance is estimated, and when it is determined that the amount of accumulation exceeds a certain value, the fuel is injected unburned upstream of the filter. Then, an endurance test was repeated for repeated forced regeneration of the filter. Then, the pressure loss of the honeycomb filter after the durability test is measured in the same manner as the initial pressure loss, and compared with the initial pressure loss, the pressure loss ratio: (pressure loss after test) / (initial pressure loss) is calculated, It is shown in Table 1.

また試験ＮＯ．１〜６のセラミックハニカムフィルタを排気系部品試験装置（図示せず）に設置し、セラミックハニカムフィルタの上流側に配置されたＬＰＧを燃料とするバーナーによりフィルタ温度を６００℃まで急加熱した後、室温まで急冷する繰り返し熱衝撃を１０回加えた後、セラミックハニカムフィルタを取り出し、流入側封止部の存在する部位で、流路に垂直方向に切断して、流入側封止部と、隔壁の境界におけるキレツの発生状況を確認し、キレツが全く認められなかったものを（◎）、軽微なキレツが認められたが実用上問題ないものを（○）、キレツ発生により流入側封止部の脱落が認められたものを（×）として表１に記載した。 Test NO. After the ceramic honeycomb filters 1 to 6 are installed in an exhaust system component testing apparatus (not shown), the filter temperature is rapidly heated to 600 ° C. with a burner using LPG disposed on the upstream side of the ceramic honeycomb filter, After 10 times of repeated thermal shocks for rapid cooling to room temperature, the ceramic honeycomb filter is taken out and cut in a direction perpendicular to the flow path at the site where the inflow side sealing portion exists, and the inflow side sealing portion and the partition wall Check the occurrence of crevices at the boundary, (◎) if no crevices were observed at all, (○) if minor crevices were observed but no problem in practical use (○). Those in which dropout was observed are shown in Table 1 as (x).

本発明の実施例である、試験ＮＯ．１〜４のセラミックハニカムフィルタは、流入側目封止部の気孔率が隔壁の気孔率より小さいことから、圧力損失比は１．０１〜１．０７の範囲であった、これに対し、比較例である、試験ＮＯ．５及び６のセラミックハニカムフィルタは、流入側目封止部の気孔率が隔壁と同じ或いは隔壁より大きいことから、圧力損失比は１．１５〜１．２１で、試験ＮＯ．１〜４より大きくなった。一方、耐熱衝撃性は、いずれも判定は（○）又は（◎）であったが、試験ＮＯ．１のセラミックハニカムフィルタは、流入側目封止の気孔率が隔壁の気孔率の０．５未満であることから判定が（○）であった。 Example No. 1 which is an example of the present invention. The ceramic honeycomb filters 1 to 4 have a pressure loss ratio in the range of 1.01 to 1.07 because the porosity of the inflow side plugged portion is smaller than the porosity of the partition wall. For example, test NO. In the ceramic honeycomb filters 5 and 6, the porosity of the inflow side plugged portion is the same as that of the partition walls or larger than that of the partition walls. It became larger than 1-4. On the other hand, the thermal shock resistance was judged as either (◯) or (◎). The ceramic honeycomb filter of No. 1 was judged as (◯) because the porosity of the inflow side plugging was less than 0.5 of the porosity of the partition walls.

以上説明してきたように、本発明のセラミックハニカムフィルタは、ディーゼル機関から排出される排気ガス中のＰＭを多孔質隔壁で捕集、浄化する構造のセラミックハニカムフィルタに好適に用いることができる。 As described above, the ceramic honeycomb filter of the present invention can be suitably used for a ceramic honeycomb filter having a structure in which PM in exhaust gas discharged from a diesel engine is collected and purified by a porous partition wall.

本発明のセラミックハニカムフィルタの模式断面図である。It is a schematic cross section of the ceramic honeycomb filter of the present invention. 本発明のセラミックハニカムフィルタ模式断面図である。1 is a schematic cross-sectional view of a ceramic honeycomb filter of the present invention. 従来のセラミックハニカムフィルタを示した模式断面図である。It is the schematic cross section which showed the conventional ceramic honeycomb filter. 従来のセラミックハニカムフィルタを示した模式断面図である。It is the schematic cross section which showed the conventional ceramic honeycomb filter. 本発明のセラミックハニカムフィルタの製造方法の一例を示す模式断面図である。It is a schematic cross section which shows an example of the manufacturing method of the ceramic honeycomb filter of this invention.

符号の説明Explanation of symbols

１：外周壁
２：隔壁
３、４：流路
５：排気ガス流入側目封止部
６：排気ガス流出側目封止部
７：排気ガス流入側端面
８：排気ガス流出側端面
１０：本発明のセラミックハニカムフィルタ
１１：セラミックハニカム構造体
１２ｕ：排気ガス流入側目封止部より上流側の隔壁
１２ｄ：排気ガス流入側目封止部より下流側の隔壁
１５：排気ガス流入側目封止部
１５ａ：排気ガス流入側目封止部の排気ガス流入側端面
１６：排気ガス流出側目封止部
１７：排気ガス流入側端面
１８：排気ガス流出側端面
３０：セラミックハニカムフィルタ
４０：少なくとも一つの排気ガス流入側目封止部が排気ガス流入側端面より離れて配置されているセラミックハニカムフィルタ
４５：排気ガス流入側目封止部
４２ｕ：排気ガス流入側目封止部より上流側の隔壁
４２ｄ：排気ガス流入側目封止部より下流側の隔壁
４５ａ：排気ガス流入側目封止部の排気ガス流入側端面
４６：排気ガス流出側目封止部
４７：排気ガス流入側端面
４８：排気ガス流出側端面
６１：管状部材
６３：チューブ
６４：バルブ
６５：樹脂製フィルム
1: outer peripheral wall 2: partition wall 3, 4: flow path 5: exhaust gas inflow side plugging portion 6: exhaust gas outflow side plugging portion 7: exhaust gas inflow side end surface 8: exhaust gas outflow side end surface 10: book Ceramic honeycomb filter of the invention 11: Ceramic honeycomb structure 12u: Partition wall upstream of the exhaust gas inflow side plugging portion 12d: Partition wall downstream of the exhaust gas inflow side plugging portion 15: Exhaust gas inflow side plugging Portion 15a: Exhaust gas inflow side end surface of the exhaust gas inflow side plugging portion 16: Exhaust gas outflow side plugging portion 17: Exhaust gas inflow side end surface 18: Exhaust gas outflow side end surface 30: Ceramic honeycomb filter 40: At least one Ceramic honeycomb filter in which two exhaust gas inflow side plugging portions are arranged apart from the end surface of the exhaust gas inflow side 45: Exhaust gas inflow side plugging portion 42u: Upstream from the exhaust gas inflow side plugging portion Side partition 42d: partition downstream of exhaust gas inflow side plugging portion 45a: exhaust gas inflow side end surface of exhaust gas inflow side plugging portion 46: exhaust gas outflow side plugging portion 47: exhaust gas inflow side End surface 48: Exhaust gas outflow side end surface 61: Tubular member 63: Tube 64: Valve 65: Resin film

Claims

多孔質セラミックハニカム構造体の所望の流路を目封止することによりハニカム構造体の隔壁に排気ガスを通過させる構造を有し、排気ガス流入側目封止部が排気ガス流入側端面から離れて配置されているセラミックハニカムフィルタにおいて、前記隔壁の気孔率が５０〜８０％、前記排気ガス流入側目封止部の気孔率が前記隔壁の気孔率より小さいことを特徴とするセラミックハニカムフィルタ。 A desired flow path of the porous ceramic honeycomb structure is plugged to allow exhaust gas to pass through the partition walls of the honeycomb structure, and the exhaust gas inflow side plugging portion is separated from the end surface of the exhaust gas inflow side. The ceramic honeycomb filter is characterized in that the partition wall has a porosity of 50 to 80% and the exhaust gas inflow side plugging portion has a porosity smaller than that of the partition wall.

前記排気ガス流入側目封止部の気孔率が前記隔壁の気孔率の０．５〜０．９倍であることを特徴とする請求項１に記載のセラミックハニカムフィルタ。 The ceramic honeycomb filter according to claim 1, wherein the porosity of the exhaust gas inflow side plugged portion is 0.5 to 0.9 times the porosity of the partition wall.

排気ガス流出側目封止部の気孔率が前記隔壁の気孔率より大きいことを特徴とする請求項１または請求項２に記載のセラミックハニカムフィルタ。 The ceramic honeycomb filter according to claim 1 or 2, wherein the porosity of the exhaust gas outflow side plugged portion is larger than the porosity of the partition wall.

前記排気ガス流出側目封止部の気孔率が９０％以下であり、かつ前記隔壁の気孔率の１．１〜１．５倍であることを特徴とする請求項３に記載のセラミックハニカムフィルタ。
4. The ceramic honeycomb filter according to claim 3, wherein the porosity of the exhaust gas outlet side plugged portion is 90% or less and 1.1 to 1.5 times the porosity of the partition wall. .