Abstract:
A black smoke purification device enabling engine performance to be retained by bringing PMs which have become giant into good contact with an oxidation catalyst. A black smoke purification device ( 100 ) comprises an inlet section ( 110 ), an installation section ( 120 ), an outlet section ( 130 ), an oxide catalyst converter ( 140 ), and a DPF ( 150 ). The oxide catalyst converter ( 140 ) includes an aggregation of cells ( 141 ) each supporting an oxide catalyst on an inner wall surface ( 143 ). The inlet-side opening area of the cell ( 141 ) is set to a size large enough for PMs (for example, soot flakes) which have emitted from an engine and have become giant to pass therethrough and set larger than the outlet-side opening area of the cell ( 141 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a black smoke purification device. 
         [0003]    2. Background Art 
         [0004]    PM (Particulate Matter) discharged from a diesel engine (hereinafter, referred to as “engine”) is constituted by soot whose main component is carbon, SOF (Soluble Organic Fraction) which is components of fuel having not burnt or lubrication oil, and the like. 
         [0005]    The SOF is vapor at high temperature. However, when the temperature decreases, the SOF is liquefied and makes soot adhere to each other. The soot tends to be discharged from the engine is adhered to each other by the SOF and enlarged, and then discharged. 
         [0006]    An art for oxidation removal of enlarged soot such as the above mentioned is disclosed in the Japanese Patent Laid Open Gazette 2002-276332 for example. 
         [0007]    A black smoke purification device disclosed in the Japanese Patent Laid Open Gazette 2002-276332 is provided therein with an oxidation catalyst converter having cells supporting an oxidation catalyst, and the density of the cells is increased from the upstream side to the downstream side. Accordingly, by diffusion of the PM in the exhaust gas, the PM touches the oxidation catalyst so that the SOF is oxidized in the cell at the upstream side and the soot is separated from the SOF. The separated soot is finely divided and oxidized in the cell at the downstream side so as to purify the exhaust gas goodly. 
         [0008]    Generally, soot discharged from an engine sticks to an exhaust pipe between a black smoke purification device and the engine. The soot is adhered by SOF similarly discharged from the engine and is accumulated, thereby becoming larger than that included in exhaust gas. Subsequently, the accumulated soot is exfoliated by vibration of the engine or the like and becomes a “soot exfoliation piece”, and then flows toward the black smoke purification device with the exhaust gas. 
         [0009]    Since the soot exfoliation piece is larger than the soot in the exhaust gas and is larger than inlet area of a cell, the soot exfoliation piece cannot flow into the cell and blocks the inlet. Therefore, the soot exfoliation piece cannot touch an oxidation catalyst, whereby good purification of the exhaust gas requires a lot of time. 
         [0010]    The blocking of the inlet of the cell by the soot exfoliation piece reduces the opening area of the whole oxidation catalyst converter so as to cause increase of exhaust pressure, thereby worsening the engine performance. 
       BRIEF SUMMARY OF THE INVENTION 
     Problems to Be Solved by the Invention 
       [0011]    The purpose of the invention is to provide a black smoke purification device enabling engine performance to be retained by making enlarged PM touch goodly an oxidation catalyst. 
       Means for Solving the Problems 
       [0012]    A black smoke purification device according to the present invention, which comprises an oxide catalyst converter having aggregate of cells each of which has an oxide catalyst supported on a wall surface of the cell, wherein PM discharged from an engine is purified by the oxide catalyst, is characterized in that inlet opening area of each of the cells is set large enough for the PM which is discharged from the engine and enlarged to pass therethrough, and is set larger than outlet opening area of the cell. 
         [0013]    Accordingly, the enlarged PM such as a soot exfoliation piece can flow into the cell so as to be finely divided and oxidized by the oxidation catalyst supported on the wall surface of the cell. 
         [0014]    With regard to the first mode according to the present invention, the oxide catalyst converter has a main body part, a first part provided at an upstream side of the main body part and having cells with larger upstream opening area than cells of the main body part, and a second part provided at an upstream side of the first part and having cells with larger upstream opening area than the cells of the main body part, and the cells of the first part and the second part are arranged alternately. 
         [0015]    Accordingly, when the enlarged PM flows into the oxidation catalyst converter, the PM collides with the end surface of the cell of the first part so as to become easy to touch the inner wall surface of the cell. 
         [0016]    With regard to the second mode according to the present invention, a notch is provided on side ends of upstream opening parts of a plurality of the cells so as to form one upstream opening by the cells as a group. 
         [0017]    Accordingly, by an easy method of processing the inlet of the conventional oxidation catalyst converter, the cell can be realized that the enlarged PM can flow into the oxidation catalyst converter goodly. 
         [0018]    Preferably, the upstream opening part formed by the notch is quadrangular pyramid-like shaped. 
         [0019]    Accordingly, the notch can be formed easily. 
         [0020]    Preferably, the upstream opening part formed by the notch is conical shaped. 
         [0021]    Accordingly, the notch can be formed easily. 
         [0022]    With regard to the third mode according to the present invention, the oxide catalyst converter has a main body part and a front part provided at an upstream side of the main body part, an exhaust gas passage which is a space in each of cells of the front part is tapered from an upstream side to a downstream side, and upstream opening area of each of the cells of the front part is larger than upstream opening area of each of cells of the main body part. 
         [0023]    Accordingly, the touching area of the PM with the oxidation catalyst converter is increased gradually toward the downstream side. 
         [0024]    Preferably, sectional shape of the exhaust gas passage is square when viewed along a direction perpendicular to flow direction of exhaust gas in the exhaust gas passage. 
         [0025]    Accordingly, the cell can be formed easily and the tapered part can be formed easily. 
         [0026]    Preferably, a communication hole communicating the exhaust gas passage of one of the cells with the exhaust gas passage of another cell is provided in the front part. 
         [0027]    Accordingly, even if the enlarged PM larger than the upstream opening flows into the oxidation catalyst converter and blocks the upstream opening of the cell, the exhaust gas flows from another cell through the communication hole into the exhaust gas passage of the blocked cell, whereby the exhaust gas is sent to the main body part uniformly so as to prevent oxidization work of the oxidation catalyst from being reduced. 
         [0028]    Preferably, a space part is provided between the main body part and the front part. 
         [0029]    Accordingly, even if the upstream openings or communication holes of a part of the cells are blocked, the exhaust gas after passing through the front part is dispersed in the space part and then supplied to the oxidation catalyst of the main body part substantially uniformly so as to prevent oxidization work of the oxidation catalyst from being reduced. 
       Effect of the Invention 
       [0030]    According to the black smoke purification device of the invention, black smoke is purified goodly and engine performance is retained by making enlarged PM touch goodly an oxidation catalyst. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES 
         [0031]    [ FIG. 1 ] It is a schematic view of a first embodiment of a black smoke purification device according to the present invention. 
           [0032]    [ FIG. 2 ] It is a drawing of oxide catalyst converter. (A) is a side view, and (B) is a sectional plan view. 
           [0033]    [ FIG. 3 ] It is a partial deal perspective view of the oxide catalyst converter shown in  FIG. 2 . 
           [0034]    [ FIG. 4 ] It is a schematic view of a second embodiment of a black smoke purification device according to the present invention. 
           [0035]    [ FIG. 5 ] It is a drawing of oxide catalyst converter. (A) is a side view, and (B) is a sectional plan view. 
           [0036]    [ FIG. 6 ] It is a partial deal perspective view of the oxide catalyst converter shown in  FIG. 5 . 
           [0037]    [ FIG. 7 ] It is a partial deal perspective view of another embodiment of the oxide catalyst converter shown in  FIG. 5 . 
           [0038]    [ FIG. 8 ] It is a schematic view of a third embodiment of a black smoke purification device according to the present invention. 
           [0039]    [ FIG. 9 ] It is a drawing of oxide catalyst converter. (A) is a side view, and (B) is a sectional plan view. 
           [0040]    [ FIG. 10 ] It is a partial deal perspective view of the oxide catalyst converter shown in  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     THE BEST MODE FOR CARRYING OUT THE INVENTION 
     First Embodiment 
       [0041]    Explanation will be given on a diesel engine black smoke purification device (hereinafter, referred to as “black smoke purification device”)  100  which is a first embodiment of a black smoke purification device according to the present invention. Hereinafter, an upstream side of flow direction of exhaust gas  10  is referred to as a front side and a downstream side thereof is referred to as a rear side, and upper, lower, left and right sides are determined on a plane perpendicular to the longitudinal direction. 
         [0042]    As shown in  FIG. 1 , the black smoke purification device  100  has an inlet section  110 , an installation section  120 , an outlet section  130 , an oxide catalyst converter  140  and a particulate filter (hereinafter, referred to as “DPF”)  150 . 
         [0043]    The exhaust gas  10  discharged from an engine is introduced through the inlet section  110  into the black smoke purification device  100 , and passes through the inlet section  110 , the oxide catalyst converter  140  and the DPF  150  arranged in the installation section  120 , and the outlet section  130  in this order. Namely, the exhaust gas  10  is purified by passing through the black smoke purification device  100  and then discharged. 
         [0044]    The inlet section  110  and the outlet section  130  are respectively formed in housings  111  and  131 . The installation section  120  is arranged between the housings  111  and  131 . The oxide catalyst converter  140  is arranged at the upstream side of the installation section  120  and the DPF  150  is arranged at the downstream side thereof respectively at predetermined intervals. 
         [0045]    Gaskets  112  and  132  attach the installation section  120  respectively to the housings  111  and  131  sealingly and detachably. 
         [0046]    An inlet pipe  116  is arranged in the inlet section  110  so as to guide the exhaust gas  10  from the engine (not shown). The inlet pipe  116  is shaped circular-cylindrically. The inlet pipe  116  passes through the inlet section  110  substantially vertically. One of the ends of the pipe is connected through an exhaust pipe (not shown) to the engine, and the other end thereof is sealed. A large number of small holes  117  are disposed in the side wall of the inlet pipe  116 . The exhaust gas  10  is introduced through the small holes  117  from the inlet pipe  116  into the inlet section  110 . 
         [0047]    A heat insulating sound absorbing material  113  is arranged in the inlet section  110 , and heat insulating sound absorbing material keep plates  114  and  115  press the heat insulating sound absorbing material  113  to the inner wall of the inlet section  110 . The heat insulating sound absorbing material  113  suppresses transmission of heat of the exhaust gas  10  introduced into the inlet section  110  to the housing  111 , and absorbs noise of the exhaust gas  10 . 
         [0048]    The outlet section  130  is provided therein with an outlet pipe  133  which discharges the exhaust gas  10  and a resonance pipe  134  which is in parallel to the outlet pipe  133  and reduces noise of discharge of the exhaust gas  10 . 
         [0049]    As shown in  FIGS. 1 to 3 , the oxide catalyst converter  140  has an aggregate of cells  141  and is honeycomb structure that the two adjacent cells  141  are partitioned by a partition  142 . The oxide catalyst converter  140  is formed by ceramic such as cordierite or metal such as stainless steel. 
         [0050]    Each of the cells  141  is tubular and the section thereof is square shaped. At the upper, lower, left and right sides of each of the cells  141 , the four adjacent cells  141  are arranged. An oxidation catalyst such as Pt is supported on an inner wall surface  143  of the cell  141 . 
         [0051]    The sectional shape of the cell  141  on the plane perpendicular to the flow direction of the exhaust gas  10  is not limited to square of this embodiment, and may alternatively be polygonal such as triangular or hexagonal, or circular. 
         [0052]    As the oxidation catalyst such as Pt or the like is used in this embodiment. However, the catalyst is not limited thereto and Pd, Rh or Ir may alternatively be used. 
         [0053]    As shown in  FIG. 1 , the DPF  150  is a honeycomb filter having an aggregate of cells  151  partitioned by perforated partitions  152 . The DPF  150  is formed by ceramic such as cordierite. The DPF  150  is a wall flow type particulate filter that sealing parts  155  are provided alternately at inlet parts  153  and outlet parts  154  of the two cells  151  arranged parallel to each other. 
         [0054]    Each of the cells  151  is tubular and the section thereof is square shaped. 
         [0055]    The sectional shape of the cell  151  on the plane perpendicular to the flow direction of the exhaust gas  10  is not limited to square of this embodiment, and may alternatively be polygonal such as triangular or hexagonal, or circular. 
         [0056]    Similarly to the oxide catalyst converter  140 , an oxidation catalyst such as Pt, Pd, Rh or Ir may be supported on the wall surface of each of the cell  151 . 
         [0057]    The exhaust gas  10  of the engine includes PM, and the PM includes soot and SOF adhering the soot. The exhaust gas  10  flow into each of the cells  141  of the oxide catalyst converter  140  while the soot is adhered by the SOF so as to be enlarged, and then touches the oxidation catalyst supported on the inner wall surface  143  of the cell  141 . Therefore, the SOF is oxidized and burnt so that the adhesiveness of the SOF is reduced. Then, the soot is pulverized (more strictly, the oxidation catalyst reduces the adhesiveness of the SOF so that the soot is separated), whereby the soot is finely divided. 
         [0058]    The soot flows from the oxide catalyst converter  140  into the DPF  150  and is collected on the surface of the perforated partitions  152 . Then, the collected soot is oxidized and burnt by nitrogen dioxide generated by the oxide catalyst converter  140 . Otherwise, in the case of supporting the oxidation catalyst on the wall surface of each of the cell  151  of the DPF  150 , the collected soot is oxidized and burnt by the oxidation catalyst. 
       [Oxide Catalyst Converter  140 ] 
       [0059]    As shown in  FIGS. 1 to 3 , the oxide catalyst converter  140  is constituted by a main body part  140   a,  a first part  140   b  and a second part  140   c.  The second part  140   c,  the first part  140   b  and the main body part  140   a  are arranged in this order along the flow direction of the exhaust gas  10  from the upstream side. 
         [0060]    The aggregate of the cells  141  is constituted by an aggregate of cells  141   a  provided in the main body part  140   a,  an aggregate of cells  141   b  provided in the first part  140   b  and an aggregate of cells  141   c  provided in the second part  140   c.    
         [0061]    The main body part  140   a  has the aggregate of the cells  141   a.  The main body part  140   a  is arranged at the downstream side, that is, the outlet side of the oxide catalyst converter  140 . The opening area of each of the cells  141   a  is set smaller than that of each of the cells  141   b  and  141   c  of the first part  140   b  and the second part  140   c.    
         [0062]    Each of the cells  141   a  is square tubular member whose lengthwise is along the flow direction of the exhaust gas  10 . At the upper, lower, left and right sides of each of the cells  141   a,  the four adjacent cells  141   a  are arranged. 
         [0063]    The first part  140   b  has the aggregate of the cells  141   b.  The first part  140   b  is arranged at the upstream side of the main body part  140   a.  The opening area of each of the cells  141   b  is set larger that of each of the cells  141   a.  Each of sides of the cell  141   b  is twice the length of that of the cell  141   a,  and the opening area of the cell  141   b  is about four times of that of the cell  141   a.    
         [0064]    Each of the cells  141   b  is square tubular member whose lengthwise is along the flow direction of the exhaust gas  10 . At the upper, lower, left and right sides of each of the cells  141   b,  the four adjacent cells  141   b  are arranged. 
         [0065]    The first part  140   b  and the main body part  140   a  are disposed continuously so that an alternate part  144  is formed in the upstream end surface of the partition  142  in each of the cells  141   a  of the main body part  140   a.  Namely, as shown in  FIG. 3 , the four cells  141   a  is connected to the one cell  141   b.  The alternate part  144  is a part of the upstream end surface of the partition  142  of the cells  141   a  facing the downstream opening surface of each of the cells  141   b  of the first part  140   b.  Accordingly, when soot flows from the cells  141   b  to the cells  141   a,  the soot collides with the alternate part  144  so as to be crushed. 
         [0066]    The second part  140   c  has the aggregate of the cells  141   c.  The second part  140   c  is arranged at the upstream side of the first part  140   b.  The opening area of each of the cells  141   c  is set substantially similarly to that of each of the cells  141   b,  and the shape of the opening of the cell  141   c  is the same as that of the cell  141   b.    
         [0067]    Each of the cells  141   c  is square tubular member whose lengthwise is along the flow direction of the exhaust gas  10 . At the upper, lower, left and right sides of each of the cells  141   c,  the four adjacent cells  141   c  are arranged. 
         [0068]    As an alternate part  145  is formed in the upstream end surface of the partition  142  in each of the cells  141   b  of the main body part  140   b,  the second part  140   c  and the first part  140   b  are disposed. Namely, as shown in  FIG. 3 , the cells  141   b  and the cells  141   c  having similar size are arranged alternately. The alternate part  145  is a part of the upstream end surface of the partition  142  of the cells  141   b  facing the downstream opening surface of each of the cells  141   c  of the second part  140   c.  Accordingly, when soot flows from the cells  141   c  to the cells  141   b,  the soot collides with the alternate part  145  so as to be crushed. 
         [0069]    The oxidation catalyst is supported on the inner wall surface  143  of each of the cells  141   a,    141   b  and  141   c.    
         [0070]    With regard to the area of the section of the cell perpendicular to the flow direction of the exhaust gas  10  (hereinafter, referred to as “the sectional area of the cell”), the sectional area of the cell  141   a  is about ¼ of the sectional area of each of the cells  141   b  and  141   c.  Namely, the sectional area of the cell  141   a  (the outlet opening of the cell  141 ) is smaller than the sectional area of the cell  141   c  (the inlet opening of the cell  141 ). Accordingly, the PM is easier to touch the oxidation catalyst on the inner wall surface  143  in the case of flowing in the cell  141   a  arranged at the downstream of the cell  141   b  rather than in the case of flowing in the cell  141   b.  Then, the touching area of the PM oxidized and finely divided in the oxide catalyst converter  140  with the cell  141   a  is secured. 
         [0071]    Explanation will be given on the case that a soot exfoliation piece which is an example of “enlarged PM” flows into the oxide catalyst converter  140 . 
         [0072]    The soot in the exhaust gas  10  discharged from the engine adheres to the exhaust pipe connecting the engine with the black smoke purification device  100  and is accumulate, thereby being enlarged. Then, the enlarged soot is exfoliated from the exhaust pipe by vibration or the like and becomes the “soot exfoliation piece”, and then flows into the oxide catalyst converter  140  (the cell  141 ). 
         [0073]    In this case, since the sectional area of the cell  141   c  (the inlet opening area of the cell  141 ) is set larger than the outline of the supposed soot exfoliation piece, the soot exfoliation piece flows into the cell  141   c.  Namely, the opening area of the cell  141   c  arranged at the inlet side of the oxide catalyst converter  140  is set so large that PM discharged from the engine can pass therethrough even if the PM is enlarged and becomes the soot exfoliation piece, and is set larger than the inlet opening area of an oxide catalyst converter provided in a general black smoke purification device. 
         [0074]    In the case that the soot exfoliation piece larger than the sectional area of the cell  141   c  flows into the converter, since the touching area of the soot exfoliation piece with the upstream opening of the cell  141   c  is small, whereby such a large soot exfoliation piece is easy to flow into the cell  141   c  by the exhaust pressure of the engine or the like. Accordingly, even if a thing larger than the soot exfoliation piece supposed previously flows into the converter, the upstream opening of the cell  141   c  is not blocked. 
         [0075]    The exhaust gas  10  including the soot exfoliation piece flowing into the cell  141   c  as mentioned above is purified as processes (1) to (4) shown below. 
         [0076]    (1) The soot touches the oxidation catalyst supported on the inner wall surface  143  of the cell  141   c  so as to be oxidized and finely divided. (2) At the time of flowing from the cell  141   c  to the cell  141   b,  the soot collides with the alternate part  145  so as to be crushed, and then flows into the cell  141   b  and touches the oxidation catalyst supported in the cell  141   b  so as to be oxidized and finely divided. (3) At the time of flowing from the cell  141   b  to the cell  141   a,  the soot collides with the alternate part  144  so as to be crushed, and then flows into the cell  141   a  and touches the oxidation catalyst supported in the cell  141   a  so as to be oxidized and finely divided. (4) The soot is discharged from the outlet of the cell  141  (the downstream opening of the cell  141   a ) and is collected by the DPF  150 . 
         [0077]    As mentioned above, with regard to the oxide catalyst converter  140 , the soot exfoliation piece can be crushed goodly by flowing into the cell  141 . Accordingly, the increase of exhaust pressure of the engine caused by the blocking of the cell  141  by the soot exfoliation piece is prevented. Then, the worsening of the exhaust efficiency of the engine which worsens fuel efficiency is prevented, and the engine performance is maintained goodly. 
         [0078]    The cell  141  is not blocked by the soot exfoliation piece so as to avoid the block situation of the oxide catalyst converter  140 , whereby the block situation of the oxide catalyst converter  140  caused by the soot exfoliation piece is prevented from being mistaken for the block situation of the DPF  150 . Therefore, the block situation of the DPF  150  can be judged certainly. 
         [0079]    As mentioned above, the PM flowing into the cell  141  is finely divided as moving toward the outlet of the cell  141 . However, the sectional area of the outlet of the cell  141  is set smaller than the sectional area of the inlet of the cell  141  and the sectional area of the passage at the downstream side is set smaller than that at the upstream side, whereby the touching of the finely divided PM with the oxidation catalyst on the inner wall surface  143  is secured. 
         [0080]    The black smoke purification device  100  has two stages of the oxide catalyst converter  140  and the DPF  150 . However, the black smoke purification device may alternatively have only one stage of the oxide catalyst converter. 
         [0081]    The oxide catalyst converter  140  has three stages of the main body part  140   a,  the first part  140   b  and the second part  140   c.  However, the oxide catalyst converter  140  may alternatively have two stages omitting the second part  140   c  or multistage that similar oxide catalyst is added before the second part  140   c.    
         [0082]    The opening area of each of the cells  141   b  and  142   c  arranged at the upstream side is about four times of that of the cell  141   a  arranged at the downstream side. However, the opening area is not limited thereto and may be changed suitably in consideration of supposed size, amount and the like of the soot exfoliation piece. 
         [0083]    The sectional area of the cell  141   b  is substantially the same as that of the cell  141   c.  However, the sectional area is not limited thereto and the sectional area of the cell  141   c  may be larger than that of the cell  141   b.  The sectional area of the cell arranged at the upstream side only has to be not smaller than that of the cell arranged at the downstream side. 
       Second Embodiment 
       [0084]    Explanation will be given on an oxide catalyst converter  240  which is a second embodiment of the oxide catalyst converter according to the present invention. 
         [0085]    As shown in  FIG. 4 , the black smoke purification device  100  has the oxide catalyst converter  240 . 
       [Oxide Catalyst Converter  240 ] 
       [0086]    As shown in  FIGS. 5 and 6 , the oxide catalyst converter  240  has an aggregate of cells  241 . Each of the cells  241  is square tubular member whose lengthwise is along the flow direction of the exhaust gas  10 . At the upper, lower, left and right sides of each of the cells  141   b,  the four adjacent cells  241  are arranged. 
         [0087]    An oxidation catalyst is supported on an inner wall surface  243  of each of the cells  241 . 
         [0088]    A notch  244  is formed at an upstream end of a partition  242  forming the side end part of the upstream opening of the cell  241 . 
         [0089]    A plurality of the cells  241  (in this embodiment, four cells  241 ) is regarded as a group of the cells and the part of the upstream end of the partition  242  which partitions the group into the cells  241  is recessed toward the downstream side so as to form the notch  244 . 
         [0090]    Accordingly, the part of the upstream end of the partition  242  which is the outer frame of the group of the cells is projected toward the upstream side from the part partitioning the group into the cells  241  so as to form one inlet. In other words, the inlets of the four cells  241  are united so as to foam the one inlet. 
         [0091]    The opening of the notch  244  formed as mentioned above is set larger than the soot exfoliation piece which is enlarged PM. 
         [0092]    The inlet of the group of the four cells  241  formed by the notch  244  is quadrangular pyramid-like shaped, and is engaged with a quadrangular pyramid-like shaped member  245  as shown in  FIG. 6 . 
         [0093]    The quadrangular pyramid-like shaped member  245  is pressed so as to be engaged with the inlet of the group of the cells while the apex of the quadrangular pyramid is projected toward the downstream side so as to form the notch  244 . 
         [0094]    As mentioned above, with regard to the oxide catalyst converter  240 , the inlets of the four cells  241  are united into the one inlet by the notch  244  so that the opening area of the united inlet is four times larger than the one cell  241 . 
         [0095]    The inlet opening area of the group of the cells formed by the four cells  241  is set larger than the supposed outline of the soot exfoliation piece so that the soot exfoliation piece flows into the cells  241 . Namely, the opening area of the notch  244  forming the opening of the cell  241  arranged at the inlet side of the oxide catalyst converter  240  is set enough large to for the PM which is enlarged to become the soot exfoliation piece to pass therethrough and is set larger than an inlet opening area of an oxide catalyst converter provided in a conventional black smoke purification device. 
         [0096]    When the soot exfoliation piece larger than the opening area of the notch  244  flows thereinto, the touching area of the soot exfoliation piece and the notch  244  is small so that such a large soot exfoliation piece is easy to flow into the cell  241  by the exhaust pressure of the engine. Accordingly, even if a thing larger than the soot exfoliation piece supposed previously flows into the converter, the upstream opening of the notch  244  is not blocked. 
         [0097]    The exhaust gas  10  including the soot exfoliation piece flowing into the cell  241  through the notch  244  as mentioned above is purified as mentioned below. 
         [0098]    The soot touches the end surface of the partition  242  which partitions the four cells  241  and in which the notch  244  is formed so as to be crushed, and then touches the oxidation catalyst supported on the wall surface  243  of the cell  241  so as to be oxidized and finely divided. On the other hand, matters such as SOF and soot included in the exhaust gas  10  touch the oxidation catalyst supported on the wall surface  243  of the cell  241  so as to be oxidized and finely divided. Then, the PM after oxidized and finely divided is discharged from the outlet of the cell  241  and collected by the DPF  150 . 
         [0099]    As mentioned above, the soot exfoliation piece reaching the inlet of the oxide catalyst converter  240  can be crushed goodly. Accordingly, the increase of exhaust pressure of the engine caused by the blocking of the cell  241  by the soot exfoliation piece is prevented. Then, the worsening of the exhaust efficiency of the engine which worsens fuel efficiency is prevented, and the engine performance is maintained goodly. 
         [0100]    The cell  241  is not blocked by the soot exfoliation piece so as to avoid the block situation of the oxide catalyst converter  240 , whereby the block situation of the oxide catalyst converter  240  caused by the soot exfoliation piece is prevented from being mistaken for the block situation of the DPF  150 . Therefore, the block situation of the DPF  150  can be judged certainly. 
         [0101]    The outlet opening area of the cell  241  is set smaller than the inlet opening area thereof so that the touching of the PM with the oxidation catalyst on the inner wall surface  243  is secured at the downstream side at which the oxidization and fine dividing have been progressed. 
         [0102]    By additional processing such as notching of a conventional oxidation catalyst carrier, the notch  244  can be provided cheaply. 
         [0103]    The black smoke purification device  100  has two stages of the oxide catalyst converter  240  and the DPF  150 . However, the black smoke purification device  100  may alternatively have only one stage of the oxide catalyst converter. 
         [0104]    The inlets of the four cells  241  are referred to as one group and the notch  244  is provided in each group. However, the number of the cells  241  included in the one group in which the notch  244  is provided is not limited and can be set suitably in consideration of the size, amount and the like of the soot exfoliation piece. 
         [0105]    The opening size, depth and the like of the notch  244  also can be set suitably in consideration of the size and the like of the soot exfoliation piece. 
         [0106]    The inlets of the cells  241  are formed by the notch  244  so as to be engaged with the quadrangular pyramid-like shaped member  245 . However, the inlets are not limited thereto and may alternatively be engaged with a conical member  246  (see  FIG. 7 ), a triangular pyramid-like shaped member or the like. The notch may alternatively be polygonal following the sectional shape of the cell. 
       Third Embodiment 
       [0107]    Explanation will be given on an oxide catalyst converter  340  which is a third embodiment of the oxide catalyst converter according to the present invention. 
         [0108]    As shown in  FIG. 8 , the black smoke purification device  100  has the oxide catalyst converter  340 . 
       [Oxide Catalyst Converter  340 ] 
       [0109]    As shown in  FIGS. 9 and 10 , the oxide catalyst converter  340  is constituted by a main body part  340   a  and a front part  340   b.  The front part  340   b  and the main body part  340   a  are arranged in this order along the flow direction of the exhaust gas  10  from the upstream side. 
         [0110]    The oxide catalyst converter  340  has an aggregate of cells  341 . The aggregate of the cells  341  is constituted by an aggregate of cells  341   a  provided in the main body part  340   a  and an aggregate of cells  341   b  provided in the front part  340   b.    
         [0111]    The main body part  340   a  has the aggregate of the cells  341   a.  The main body part  340   a  is arranged at the downstream side, that is, the outlet side of the oxide catalyst converter  340 . The opening area of each of the cells  341   a  is set smaller than the opening area of each of the cells  341   b  of the front part  340   b.    
         [0112]    Each of the cells  341   a  is square tubular member whose lengthwise is along the flow direction of the exhaust gas  10 . At the upper, lower, left and right sides of each of the cells  341   a,  the four adjacent cells  341   a  are arranged. 
         [0113]    The front part  340   b  has the aggregate of the cells  341   b.  The front part  340   b  is arranged at the upstream side of the main body part  340   a.  The opening area of each of the cells  341   b  is set larger than the opening area of each of the cells  340   a.  The upstream opening area of each of the cells  341   b  of the front part  340   b  is about four times larger than the cell  341   a  of the main body part  340   a    
         [0114]    Each of the cells  341   b  is square tubular member whose lengthwise is along the flow direction of the exhaust gas  10 . At the upper, lower, left and right sides of each of the cells  341   b,  the four adjacent cells  341   b  are arranged. 
         [0115]    An exhaust gas passage  344  which is a space in each of the cells  341   b  of the front part  340   b  is tapered from the upstream side to the downstream side so that the passage becomes narrow toward the downstream side. The upstream opening area of the cell  341   b  is set larger than the soot exfoliation piece which is an example of the enlarged PM. 
         [0116]    Each of the cells  341   b  of the front part  340   b  is stacked with the aggregate of the four cells  341   a  of the main body part  340   a  in which the four adjacent cells  341   a  are arranged at the upper, lower, left and right sides of each of the cells  341   a.    
         [0117]    The sectional shape of the exhaust gas passage  344  is square when viewed along the direction perpendicular to the flow direction of the exhaust gas  10 . 
         [0118]    An oxidation catalyst is supported on an inner wall surface  343  of each of the cells  341   a  and  341   b.    
         [0119]    A plurality of communication holes  345 , which communicate the exhaust gas passage  344  of one of the cells  341   a  with the exhaust gas passage  344  of another cell  341   a,  are formed in four partitions  342  at the upper, lower, left and right sides of the front part  340   b.    
         [0120]    Each of the communication holes  345  is constituted by a first communication hole  345   a  at the upstream side and a second communication hole  345   b  at the downstream side about the first communication hole  345   a.  The first communication hole  345   a  and the second communication hole  345   b  are extended perpendicularly to the flow direction of the exhaust gas  10  and connected to the exhaust gas passages  344  of the four cells  341   b  adjacent at the upper, lower, left and right sides. The sectional shape of each of the first communication hole  345   a  and the second communication hole  345   b  is square. However, the sectional shape is not limited thereto and may alternatively be circular or the like. 
         [0121]    A space part  346  in which any cell does not exist is provided between the front part  340   b  and the main body part  340   a  of the oxide catalyst converter  340 . The front part  340   b  and the main body part  340   a  are communicated with each other through the space part  346 . 
         [0122]    As mentioned above, with regard to the oxide catalyst converter  340 , the upstream opening area of each of the cells  341   b  arranged at the upstream side is set larger than the supposed outline of the soot exfoliation piece so that the soot exfoliation piece flows into the cells  341   b.  Namely, the opening area of each of the cells  341   b  arranged at the inlet side of the oxide catalyst converter  340  is set enough large to for the PM which is enlarged to become the soot exfoliation piece to pass therethrough and is set larger than an inlet opening area of an oxide catalyst converter provided in a conventional black smoke purification device. 
         [0123]    In the case that the soot exfoliation piece larger than the upstream opening area of the cell  341   b  flows into the converter, since the touching area of the soot exfoliation piece with the upstream opening of the cell  341   b  is small, whereby such a large soot exfoliation piece is easy to flow into the cell  341   b  by the exhaust pressure of the engine or the like. Accordingly, even if a thing larger than the soot exfoliation piece supposed previously flows into the converter, the upstream opening of the cell  341   b  is not blocked. 
         [0124]    The exhaust gas  10  flowing into one of the exhaust gas passages  344  can flow into another exhaust gas passage  344  through the first communication hole  345   a  and the second communication hole  345   b.  Accordingly, the flow of the exhaust gas  10  is dispersed by the first communication hole  345   a  and the second communication hole  345   b  so as to be prevented from flowing certain one of the exhaust gas passages  344  concentratedly. Then, the exhaust gas  10  flows uniformly from the front part  340   b  to the main body part  340   a  and touches the oxide catalyst of the main body part  340   a  in each of the cells  341   a,  whereby the area in which the oxide catalyst of the main body part  340   a  works effectively is secured efficiently. 
         [0125]    The space part  346  is provided between the front part  340   b  and the main body part  340   a  so that the exhaust gas  10  discharged from the front part  340   b  is spread once in the space part  346  and then supplied to each of the cells  341   a  of the main body part  340   a  uniformly. Accordingly, the exhaust gas  10  touches the oxide catalyst of the main body part  340   a  in each of the cells  341   a,  whereby the area in which the oxide catalyst of the main body part  340   a  works effectively is secured efficiently. 
         [0126]    The exhaust gas  10  including the soot exfoliation piece flowing into the cell  341   b  as mentioned above is purified as mentioned below. 
         [0127]    The soot exfoliation piece flows into the cell  341   b  and touches the oxidation catalyst supported on the wall surface  343  of the cell  341   b  so as to be oxidized and finely divided. On the other hand, matters such as SOF and soot included in the exhaust gas  10  touch the oxidation catalyst supported on the wall surface  343  of each of the cells  341   a  and  341   b  so as to be oxidized and finely divided. Then, the PM after oxidized and finely divided is discharged from the outlet of the cell  341   a  and collected by the DPF  150 . 
         [0128]    As mentioned above, the soot exfoliation piece reaching the inlet of the oxide catalyst converter  340  can be crushed goodly. Accordingly, the increase of exhaust pressure of the engine caused by the blocking of the cells  341   a  and  341   b  by the soot exfoliation piece is prevented. Then, the worsening of the exhaust efficiency of the engine which worsens fuel efficiency is prevented, and the engine performance is maintained goodly. 
         [0129]    Each of the cells  341   a  and  341   b  is not blocked by the soot exfoliation piece so as to avoid the block situation of the oxide catalyst converter  340 , whereby the block situation of the oxide catalyst converter  340  caused by the soot exfoliation piece is prevented from being mistaken for the block situation of the DPF  150 . Therefore, the block situation of the DPF  150  can be judged certainly. 
         [0130]    The outlet opening area of the cell  341   a  is set smaller than the inlet opening area the cell  341   b  so that the touching of the PM with the oxidation catalyst on the inner wall surface  343  is secured at the downstream side at which the oxidization and fine dividing have been progressed. 
         [0131]    The black smoke purification device  100  has two stages of the oxide catalyst converter  140  and the DPF  150 . However, the black smoke purification device  100  may alternatively have only one stage of the oxide catalyst converter. 
         [0132]    The opening area of each of the cells  341   b  arranged at the upstream side is about four times of that of the cell  341   a  arranged at the downstream side. However, the opening area is not limited thereto and may be changed suitably in consideration of supposed size, amount and the like of the soot exfoliation piece. 
         [0133]    Each of the communication holes  345  is constituted by two stages of the first communication hole  345   a  at the upstream side and the second communication hole  345   b  at the downstream side. However, the communication hole  345  may alternatively be constructed by one stage, three stages or the like. 
         [0134]    When enough dispersion can be obtained by changing the size or position of the first communication hole  345   a  and the second communication hole  345   b,  the space part  346  may be omitted. 
       INDUSTRIAL APPLICABILITY 
       [0135]    The present invention is adoptable to a black smoke purification device which purifies PM discharged from an engine.