Abstract:
Apparatus for attenuating particulate matter and volatile organic compounds in exhaust gases of diesel engines. The apparatus includes a housing disposed serially relative to exhaust gas flow. The housing encloses mechanical filters having gas orifices of different sizes, and after the filters, a low temperature, low restriction catalytic converter. Pressure may be monitored to infer clogging by particulates. Clogging may be annunciated by an indicating light. Individual filters may be contained within plural separate filter canisters, which may be removed for cleaning. The housing may be substantially of aluminum, having cooling fins and a longitudinally oriented mounting foot. Filters may be arranged such that their orifices are misaligned to promote separation of particulates from the exhaust gases.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to treatment of exhaust of diesel engines, and more particularly to a filter for attenuating diesel particulate emissions as the emissions are produced. 
       BACKGROUND OF THE INVENTION 
       [0002]    Diesel engines are subject to limitations on exhaust emissions as are gasoline engines, although the nature of diesel emissions differs from that of gasoline exhaust products. Under ideal conditions, diesel emissions are quite limited. However, under less than optimum conditions, diesel engines produce objectionable exhaust borne substances. 
         [0003]    Some of the emitted substances are volatile organic compounds, which may result from high pressures in combination with relatively fuels of relatively complex hydrocarbon structure such as cetane. Other substances include particulate matter, popularly known as soot. Particulate matter is heavily carbonaceous, but may include volatile organic compounds, and is produced mostly when a diesel engine is lightly loaded. This is because under light loading, combustion chamber temperatures are sufficiently cool to the point that not all of the hydrocarbon fuel compounds burn to completion. 
         [0004]    There exists a need to address diesel exhaust emissions of organic particulate matter and volatile organic compounds. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides apparatus for trapping and attenuating organic particulate matter or both particulate matter and volatile organic compounds, in diesel exhaust gases. The apparatus may comprise a random series of filters or screens of different orifice size, which may operate in conjunction with a catalyst. For example, the series of filers or screens can have progressively smaller orifice size. The filters and catalyst, where the latter is used, may be contained within a housing adapted to transfer exhaust heat to ambient air, thereby lowering exhaust temperatures and promoting precipitation of gas borne particulates. The catalyst may be a low temperature, low restriction catalyst. The housing, together with the filters and catalyst, may be installed in series within the exhaust system of a diesel engine. Pressure sensors may be used to sense impending clogging of the filters, at which point the apparatus may be serviced by disassembling and cleaning, then reinstalled. An alarm such as an indicating light may be illuminated to alert the operator of the diesel powered equipment that clogging has occurred. 
         [0006]    It is an object of the invention to provide apparatus for separating and trapping particulate material from diesel exhaust gases. 
         [0007]    It is an object of the invention to provide improved elements and arrangements thereof by apparatus for the purposes described which is inexpensive, dependable, and fully effective in accomplishing its intended purposes. 
         [0008]    These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Various objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
           [0010]      FIG. 1  is a side view of an apparatus for attenuating particulate matter in the exhaust of a diesel engine, according to at least one aspect of the invention. 
           [0011]      FIG. 2  is a perspective view of the housing of the apparatus of  FIG. 1 . 
           [0012]      FIG. 3  is an end view of the housing of  FIG. 2 , but also showing a mechanical baffle or filter. 
           [0013]      FIG. 4  is an exploded perspective view of the housing of  FIG. 2 , but also showing internal components of the housing. 
           [0014]      FIG. 5  is a diagrammatic representation of exhaust gas passage orifice sizes and an order in which they could be arrayed in the apparatus of  FIG. 1 . 
           [0015]      FIG. 6  is an enlarged perspective detail view showing misalignment of exhaust gas passage orifices. 
           [0016]      FIG. 7  is a diagrammatic side view of an apparatus for attenuating particulate matter in the exhaust of a diesel engine, according to at least one further aspect of the invention. 
           [0017]      FIG. 8  is a diagrammatic side view similar to  FIG. 7 , showing a still further aspect of the invention. 
           [0018]      FIG. 9  is a diagrammatic side view of an apparatus for attenuating particulate matter in the exhaust of a diesel engine, according to yet another aspect of the invention. 
           [0019]      FIG. 10  is a diagrammatic representation of mechanical baffles or filters separated by metallic spacer rings. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Referring first to  FIG. 1 , according to at least one aspect of the invention, there is shown an apparatus  100  for attenuating particulate matter in the exhaust of a diesel engine (not shown). Where used as a noun, “exhaust” implies a mixture comprising primarily gases, possibly with liquids either liquid form entrained therein or in gaseous form or both, and also possibly with solid particulate matter which is borne in the gases. The apparatus  10  is to be installed in series with the flow of exhaust gases, and upon casual inspection may appear similar to a muffler, resonator, or in-line catalytic converter of a conventional automotive exhaust system (not shown). The apparatus  100  may comprise a housing  102  having a circumferential wall  104  extending along the length of the housing  102 , a longitudinal axis  105 , an inlet end  106 , and an outlet end  108 . For purposes of description, the inlet end  106  is located at the left in  FIG. 1 , and is that end which receives incoming exhaust gases which flow in the direction indicated by an arrow  110 . Correspondingly, the exhaust gases exit the apparatus  10  as indicated by an arrow  112  located proximate the outlet end  108 . The inlet end  106  and the outlet end  108  may each comprise respective conical sections  114 ,  116 , and annular stub ends  118 ,  120 . The circumferential wall  104  is seen to bear a plurality of external cooling fins  122 ,  124 ,  126 ,  128 ,  130 . 
         [0021]    Referring also to  FIG. 2 , the housing  102  is also seen to comprise a mounting flange  132  extending in the longitudinal direction. That is, the length of the mounting flange  132  is aligned with the length of the mounting flange  132 . The mounting flange  132  may have a flat bottom surface  134  which faces away from the circumferential wall  104 , thereby presenting a planar surface which could be exploited for example to stably seat the apparatus  100  against a flat surface of a vehicle or equipment (neither shown) having a diesel engine. The flat bottom surface  134  is advantageous since the general configuration of the housing is mostly cylindrical. The mounting flange  132  may also comprise a first projecting member  136  and an opposed second projecting member  138  which are generally tangential to the housing  102 . The projecting members  136 ,  138  could be utilized to mount the apparatus  100  to a cooperatively shaped bracket (not shown) for example. 
         [0022]    It will also be seen that the cooling fins  122 ,  124 ,  126 ,  128 ,  130  may have counterparts on the opposed side of the housing  102  in the form of cooling fins  140 ,  142 ,  144 ,  146 ,  148 . 
         [0023]    Turning now to  FIG. 3 , particulate matter is separated from the exhaust gases at least in part by a plurality of mechanical baffles or filters (only one mechanical filter  150  being visible in  FIG. 3 ). Each mechanical filter  150  may comprise an aluminum or other metallic plate bearing a great many exhaust gas passage orifices  152 . As employed herein, the term “aluminum” encompasses any metallic composition which is substantially aluminum, and includes alloys comprising mostly aluminum. Also referring to  FIG. 4 , mechanical filters  150  may be arranged in serial, spaced apart relation within filter canisters  154 ,  156 ,  158 ,  160 . The filter canisters  154 ,  156 ,  158 ,  160  which may also comprise aluminum or other metallic constituency, are arranged serially within the chamber  162  defined by the open interior of the housing  102 . There may be for example four filter canisters  154 ,  156 ,  158 ,  160  contained within the housing  102 , each filter canister  154 ,  156 ,  158  or  160  containing a plurality of mechanical filters  150 . Metallic spacer rings  164  may be provided to separate and space apart adjacent mechanical filters  150 . Alternative to using rings  164 , the filter can have a footing about its perimeter. 
         [0024]    As shown diagrammatically in  FIG. 5 , exhaust gas passage orifices  152  may be of different sizes, such as differing in diameter. Within each one of the filter canisters  154 ,  156 ,  158 ,  160 , the mechanical filters  150  contained therein are arranged in a random order. For example, the series can include an order such that no exhaust gas passage orifice  150  is of greater orifice size than that of any exhaust gas passage orifice  150  which is closer to the inlet end  106  of the housing  102 . Alternatively stated, and as shown in  FIG. 5 , within each one of the filter canisters  154 ,  156 ,  158 ,  160  exhaust gas passage orifices  150  are arrayed in order of relatively large to relatively small sizes starting at that end of each filter canister  154 ,  156 ,  158  or  160  which is closer to the inlet end  106 , and proceeding towards that end of each filter canister  154 ,  156 ,  158  or  160  which is closer to the outlet end  108 . This pattern of progressively decreasing orifice size, seen in  FIG. 5  as orifices  166 ,  168 ,  170 ,  172 , which collectively provide four progressively smaller sizes, considered starting from the left, may be repeated after the first filter canister  154  in each and every succeeding filter canister such as the filter canisters  156 ,  158 ,  160 . This does not necessarily imply that the exhaust gas passage orifices  150  of every succeeding mechanical filter  150  be smaller in size than those of a predecessor mechanical filter  150  closer to the inlet end  106 . It would be possible for example to provide in series two mechanical filters  150  having the same exhaust gas passage orifice size before making the transition to a mechanical filter  150  having an exhaust gas passage orifice  152  of a different size. 
         [0025]    It should be noted at this point that orientational terms such as predecessor refer to the direction of flow of exhaust gases through the device in normal use. As illustrated in  FIG. 1 , the flow of exhaust gases if from left to right. 
         [0026]    As seen in  FIG. 6 , adjacent mechanical filters  150  may be staggered or otherwise arranged to assure that an exhaust gas passage orifice  152  of any one of the mechanical filters  150  is out of linear registry with the exhaust gas passage orifices  152  of an adjacent mechanical filter  150 . In  FIG. 6 , it is seen that the center line  174  of one exhaust gas passage orifice  152 , when extended, intercepts the solid wall of the adjacent mechanical filter  150 , and is not in registry or alignment with the exhaust gas passage orifices  152  of the adjacent mechanical filter  150 . 
         [0027]    The housing  102  may be of aluminum in whole or in part. Because of metal consitutuency and of close fit, the relation of the mechanical filters  150 , the filter canisters  154 ,  156 ,  158 ,  160 , and the housing  102  is such that all of these are disposed in heat transfer relation to one another. 
         [0028]    The inlet end  106  of the housing  102  transfers exhaust heat to ambient air. As seen in  FIG. 1 , the interior  176  as well as the outer surface  178  of the inlet end  106  are conical. As employed herein, the term “conical” will be understood to encompass frustoconical. This sudden widening of the gas passage defined within the interior  176  of the inlet end  106  may promote precipitation or other separation of particulate matter from the exhaust. It is possible that liquids such as water and volatile organic compounds such as chlorobenzene are removed from the more carbonaceous particulates by being boiled off, thereby enabling entrapment of particulate matter either within the inlet end  106  or in the interstitial spaces separating adjacent mechanical filters  150 . It may also be that the frustoconical interior of the inlet end  106  promotes vortex flow of exhaust therein. Therefore, the conical configuration and open interior of the inlet end  106  may cause at least some separation of particulate matter from exhaust flowing through the apparatus  100  occurs at the inlet end  106  of the housing  102 . 
         [0029]    The apparatus  100  may comprise a pressure sensing arrangement which may be used to determine by inference whether the apparatus  100  has become clogged by particulate matter which has been separated from the exhaust gases. This may be implemented in several ways. As seen in  FIG. 7 , determination of clogging by the pressure sensing arrangement may utilize a pressure sensor  180  mounted to the inlet end  106 , and is based on a threshold of a single predetermined pressure value being exceeded within the opening  176  of the inlet end  106 . For example, in a typical diesel powered vehicle (not shown), should exhaust pressures exceed thirty-five pounds per square inch, it may be inferred that exhaust pressure is increasing due to filter clogging. Responsively to exceeding the predetermined pressure value, an alarm such as an indicating light  182  may be illuminated. 
         [0030]    In another implementation seen in  FIG. 8 , determination of clogging by the pressure sensing arrangement utilizes a first pressure sensor  184  disposed to sense exhaust gas pressures proximate or at the inlet end  106  and a second pressure sensor  186  disposed to sense exhaust gas pressures proximate or at the outlet end  108 . In the arrangement of  FIG. 8 , determination of clogging by the pressure sensing arrangement is based on a threshold of a differential in pressures sensed by the first pressure sensor  184  and the second pressure sensor  186  being exceeded. Responsively to determining clogging, an alarm such as an indicating light  188  may be illuminated. Signals from the first pressure sensor  184  and the second pressure sensor  186  may be processed by a processor  190  in order to generate a signal to operate the indicating lamp  188 . 
         [0031]    Referring again to  FIG. 4 , the apparatus  100  may comprise a catalytic converter  192  disposed serially within the housing  102  on that side of the mechanical filters  150  which is proximate the outlet end  108  (see  FIG. 1 ). The catalytic converter  192  may be for example, a low temperature, low restriction catalytic converter having characteristics of the type sold by the Camet Company of the Davison Division of W. R. Grace, Inc., and which is in use for example in electrical power generating facilities. 
         [0032]      FIG. 9  shows a variation on the arrangement of  FIG. 1 , which variation may include the functional features of the arrangement of  FIG. 1 . In  FIG. 9 , there is shown an apparatus  200  comprising a first section  202  and a second section  204 . The first section  202  may contain and enclose filter canisters and mechanical filters such as the filter canisters  154 ,  156 ,  158 ,  160 , the mechanical filters  150 , and spacer rings such as the spacer rings  164 . The second section  204  may contain and enclose a catalytic converter (not visible, but corresponding to the catalytic converter  192  of  FIG. 4 ). A connecting conduit  206  may connect the first section  202  to the second section  204 . It will be seen that the first section  202  has a first diameter  208 , the second section  204  has a second diameter  210 , and the connecting conduit  206  has a third diameter  212  which is less in magnitude than the first diameter  208  and the second diameter  210 . This construction would result for example where the catalytic converter  192  is purchased commercially with its own housing  214 , and need only be connected to the first section  202  by for example welding a section of pipe between the two sections  202 ,  204 . 
         [0033]    Although the invention has been described in terms of certain components being referred to in either the singular or the plural, other arrangements are possible. For example, it is to be understood that due to the conceptual description presented herein, components presented in the singular may be provided in the plural. Illustratively, the catalytic converter may be provided in plural segments or plural catalytic converter assemblies (this option is not shown). 
         [0034]    The present invention is susceptible to modifications and variations which may be introduced thereto without departing from the inventive concepts. For example, exhaust gas passage orifices  152  of individual mechanical filters  150  may vary in configuration, orientation, and in other ways. Also, a housing corresponding to the housing  102  may vary in cross sectional configuration, being rectangular, oblong, irregular in cross section, for example. The frustoconical configuration of the inlet end  106  and the outlet end  108  could be belled or otherwise curved or varied. 
         [0035]    The number, size, and arrangement of cooling fins such as the cooling fins  122 ,  124 ,  126 ,  128 ,  130 ,  140 ,  142 ,  144 ,  146 ,  148  may be varied as desired. 
         [0036]    The mounting flange  132  may be drilled to accept threaded fasteners if desired (this option is not shown). 
         [0037]    While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is to be understood that the present invention is not to be limited to the disclosed arrangements, but is intended to cover various arrangements which are included within the spirit and scope of the broadest possible interpretation of the appended claims so as to encompass all modifications and equivalent arrangements which are possible.