Abstract:
A particulate trap has a plurality of filters and an air distributor. The air distributor has an inner tube and an outer tube. Each of the inner and outer tubes have a plurality of openings to allow exhaust flow to the plurality of filters. One of the inner and outer tubes is rotatable to selectively block exhaust flow to at least one of the plurality of filters at a given time.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates generally to a particulate trap, and more particularly to a particulate trap having regeneration capabilities.  
       BACKGROUND  
       [0002]     Engines, including diesel engines, gasoline engines, natural gas engines, and other engines known in the art, may exhaust a complex mixture of air pollutants. The air pollutants may be composed of gaseous and solid material, which include particulate matter. Particulate matter may include unburned carbon particles, which are also called soot.  
         [0003]     Due to increased attention on the environment, exhaust emission standards have become more stringent. The amount of particulates emitted from an engine may be regulated depending on the type of engine, size of engine, and/or class of engine. One method that has been implemented by engine manufacturers to comply with the regulation of particulate matter exhausted to the environment has been to remove the particulate matter from the exhaust flow of an engine with a device called a particulate trap. A particulate trap is a filter designed to trap particulate matter and consists of a wire mesh medium. However, the use of the particulate trap for extended periods of time may cause the particulate matter to buildup in the wire mesh, thereby causing the functionality of the filter and engine performance to decrease.  
         [0004]     One method of improving the performance of the particulate trap may be to implement regeneration. For example, U.S. Pat. No. 6,572,682 (the &#39;682 patent) issued to Peter et al. on Jun. 3, 2003, describes using a self-cleaning filter system to remove particulate matter from an exhaust flow of an engine. The filter system of the &#39;682 patent is designed for use in a diesel engine and comprises a filter media stack having a plurality of sub-cartridges. Exhaust flow is directed through each of the sub-cartridges via damper valves, to remove particulate matter from the exhaust flow. A heater is used to increase the temperature of the filter and the trapped particulate matter above the combustion temperature of the particulate matter, thereby burning away the collected particulate matter and regenerating the filter system.  
         [0005]     Although the filter system of the &#39;682 patent may reduce the particulate matter exhausted to the environment and reduce the buildup of particulate matter in the filter system, the filter system may be complex and costly. In addition, the large size of the filter system of the &#39;682 patent may be incompatible with the limited space within an engine compartment.  
         [0006]     The present invention is directed to overcoming one or more of the problems set forth above.  
       SUMMARY OF THE INVENTION  
       [0007]     In one aspect, the present disclosure is directed to a particulate trap that includes a plurality of filters and an air distributor. The air distributor includes an inner tube and an outer tube. Each of the inner and outer tubes have a plurality of openings to allow exhaust flow to the plurality of filters. One of the inner and outer tubes is rotatable to selectively block exhaust flow to at least one of the plurality of filters at a given time.  
         [0008]     In another aspect, the present disclosure is directed to a method of removing particulates from an exhaust flow. The method includes selectively directing exhaust flow to at least one filter and filtering particulates out of the exhaust flow with the at least one filter. The method also includes rotating one of an inner tube and an outer tube of an air distributor to selectively block the exhaust flow to the at least one filter. The method further includes selectively applying electrical current to at least one filter section of the at least one filter to cause regeneration of the at least one filter section. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a diagrammatic illustration of an engine having a particulate trap according to an exemplary embodiment of the present disclosure;  
         [0010]      FIG. 2  is a front view diagrammatic illustration of a particulate trap according to an exemplary embodiment of the present disclosure;  
         [0011]      FIG. 3  is a side view diagrammatic illustration of a particulate trap according to an exemplary embodiment of the present disclosure;  
         [0012]      FIG. 4  is a perspective illustration of an inner tube of a particulate trap according to an exemplary embodiment of the present disclosure;  
         [0013]      FIG. 5  is a cross-sectioned top diagrammatic view of a particulate trap according to an exemplary embodiment of the present disclosure;  
         [0014]      FIG. 6  is a cross-sectioned top diagrammatic view of a particulate trap according to an another exemplary embodiment of the present disclosure;  
         [0015]      FIG. 7   a  is a diagrammatic illustration of exemplary alternate embodiments of a component of the present disclosure;  
         [0016]      FIG. 7   b  is a perspective illustration of a filter for use in a particulate trap according to an exemplary embodiment of the present disclosure;  
         [0017]      FIG. 7   c  is a perspective illustration of a filter for use in a particulate trap according to another exemplary embodiment of the present disclosure; and  
         [0018]      FIG. 8  is a perspective illustration of a filter for use in a particulate trap according to another exemplary embodiment of the present disclosure. 
     
    
     DETAILED DESCRIPTION  
       [0019]      FIG. 1  illustrates an engine  10  having an exemplary embodiment of a particulate trap  12 . Engine  10  may include an exhaust manifold  14  connecting an exhaust flow of engine  10  with an inlet  16  of particulate trap  12 . A controller  18  may be in communication with particulate trap  12  via a communication line  20 , and with a motor  22  via a communication line  24 .  
         [0020]     As illustrated in  FIGS. 2 and 5 , particulate trap  12  may include an air distributor  26 , an flow tube  32 , one or more insulating dividers  28 , one or more filters  30 , and a filter housing  34 .  
         [0021]     Referring to  FIG. 2 , air distributor  26  may include an inner tube  36  and an outer tube  38 . Outer tube  38  may include an open end  40 , a closed end  42 , and a single column of openings  46  through an outer cylindrical surface  48 . In certain embodiments, the openings may have a generally rectangular shape. The single column of openings  46  may be parallel with an axis  50  of outer tube  38 . Openings  46  may be oriented away from filters  30  relative to axis  50  to facilitate even distribution of the exhaust flow across filters  30 . Inner tube  36  may be rotatably disposed within outer tube  38  and may also have an open end  52  and a closed end  54 . Inner tube  36  may be configured to rotate while outer tube  38  remains stationary. Alternately, inner tube  36  may remain stationary while outer tube  38  rotates.  
         [0022]     Inner tube  36  may have multiple columns of openings  56  through an outer cylindrical surface  58 . In certain embodiments, the openings may have a generally rectangular shape. Each column of openings  56  may also be parallel with axis  50 . As best illustrated in  FIG. 4 , each column of openings  56  may include at least one opening fewer than the number of openings  46  in the single column of openings of outer tube  38 , such that when any one column of openings  56  is aligned with openings  46 , at least one of openings  46  is blocked. For example, opening  46   a  is blocked in  FIG. 2 . The position of the blocked opening may be vertically different relative to axis  50  for each column of openings  56 , such that as the inner tube  36  rotates one complete rotation, each of openings  46  is blocked at least once.  
         [0023]     Flow tube  32  may also include openings similar to inner and outer tubes  36  and  38 . For example, flow tube  32  may include an open end  70 , a closed end  72 , and a single column of openings  74  through an outer cylindrical surface  76 . The number of openings  74  may be equal to the number of openings  46 .  
         [0024]     One or more insulating dividers  28  may separate one filter  30  from another filter  30  to create filter divisions within particulate trap  12 . Each division  30  may be in fluid communication with one or more of openings  46  and one or more of openings  74 . Each filter  30  may be modular and independently replaceable. In addition, each filter  30  may include one or more filter sections  64 .  
         [0025]     As illustrated in the different exemplary embodiments of a particulate trap  12  of  FIGS. 5 and 6 , each of filter sections  64  may be permanent sub-cartridges of a filter  30  and may include corrugated wire-mesh media  65  that are electrically conductive and separated from each other and from housing  34  by additional insulating members  66  and  67 . Alternately, each of filter sections  64  may include a non-conductive ceramic filter media having electrically conductive fibers. Each of filter sections  64  may be stacked in rows, columns, and/or layers.  FIGS. 2, 3  and  5  illustrate an embodiment where filter sections  64  are stacked in layers, while  FIG. 6  illustrates an embodiment where filter sections  64  are stacked in columns.  
         [0026]      FIG. 7   a  illustrates a number of exemplary alternative holding members ( 86 ,  88 ,  90 ,  92 , and  94 ) used for stacking one filter section  64  on another filter section  64 , and for insulating one filter section  64  from another filter section  64 . Only one type of holding member would typically be used in a particular trap. The holding members may or may not be composed of electrically-conductive material. The holding members composed of electrically-conductive material may be coated with alumina or other suitable coating to provide electrical insulation between the wire mesh media  65  of filter sections  64 . Each of the holding members may include a base portion  80 , a first side portion  82 , and a second side portion  84 . The base portion  80  may separate one wire mesh media  65  from another wire mesh media  65 , while the first and second side portions  82  and  84  may be used to laterally position one filter section  64  relative to another filter section  64 .  
         [0027]     A first holding member  86  may be composed of two U-shaped metal sections welded together to form a member having a substantially I-shaped cross-section. The two U-shaped members may be arranged such that two openings oppose each other and can each hold a respective filter section  64 . A second holding member  88  may be composed of a single folded metal piece. The single folded metal piece may include identical first and second sides connected via a main fold. Each of the first and second sides may include an end portion bent to engage a side of respective filter sections  64 , while the main fold is configured to engage the opposite sides of both joined filter sections  64 . A third holding member  90  may be composed of an extruded metal member having a substantial I-shape. Each end of the I-shape may be configured to engage opposing sides of two filter sections  64 . A fourth holding member  92  may be composed of a cast member that is also substantially I-shaped, with at least one bump configured to engage a corrugated portion of the respective filter sections  64  for positioning purposes. A fifth holding member  94  may be composed of a non-metallic piece that also includes a substantially I-shaped cross-section. The holding member may also be a flat plate (not shown).  
         [0028]     Each of the holding members may have a smooth planar surface for receiving the corrugated wire mesh media  65 , as illustrated in  FIG. 7   b . Alternately, the fifth holding member  94  may include a surface having a serpentine impression configured to match the corrugated shape of wire mesh media  65  as illustrated in  FIG. 7   c.    
         [0029]      FIG. 8  illustrates a sixth holding member  96  composed of a serpentine shape having a constant, substantially I-shaped cross-section. The sixth holding member  96  may include side members configured to be fitted, sealed, or crimped to two filter sections  64 .  
         [0030]     Electrical connectors  68  and  69  (referring to  FIGS. 3, 5 , and  6 ) may connect one or more filter sections  64  to a power source (not shown) to form an electrical circuit. Electrical connectors  69  may be connected to each other via a common bus bar  98 .  
         [0031]     Controller  18  ( FIG. 1 ) may include all the components to operate particulate trap  12  such as, for example, a memory, a secondary storage device, and a processor. Various circuits may be associated with controller  18  such as, for example, power supply circuitry, signal conditioning circuitry, solenoid driver circuitry, and other appropriate circuitry.  
         [0032]     Motor  22  ( FIG. 1 ) may be connected to inner tube  36  to cause inner tube  36  to rotate. Inner tube  36  may be continuously rotated or rotated in a step-wise manner. Motor  22  may be electrically driven, mechanically driven, hydraulically driven, or driven in any other manner known in the art. Motor  22  may be directly connected to inner tube  36  or may be connected to inner tube  36  via a ratcheting device, a gear mechanism, or in any other appropriate manner known in the art.  
       Industrial Applicability  
       [0033]     The disclosed particulate trap may be applicable to any combustion-type device such as, for example, an engine, a furnace, or any other device known in the art where the removal of particulate matter from an exhaust flow is desired. Particulate trap  12  may allow for a less complex, cheaper, and more compact alternative for reducing the amount of particulate matter exhausted to the environment. In addition, because the disclosed particulate trap  12  does not require a centralized valve assembly, the particulate trap may have increased design flexibility. In particular, the external shape and configuration of the disclosed particulate trap  12  is not limited to a central structure and may, therefore, be modified to accommodate a variety of packaging environments. The operation of particulate trap  12  will now be explained in detail.  
         [0034]     According to an exemplary embodiment of particulate trap  12 , exhaust flow may be directed into particulate trap  12  through air distributor  26 , as illustrated in  FIG. 2 . The exhaust flow may be directed through holes  56  of inner tube  36 , through openings  46  of outer tube  38 , through filters  30 , and out of particulate trap  12  via flow tube  32 . It is also contemplated that the flow of the particulate trap  12  may be reversed, with the flow entering through flow tube  32 , flowing through filters  30  and exiting out through inner and outer tubes  36  and  36 .  
         [0035]     As exhaust flows through the filters  30 , particulate matter may be removed from the exhaust flow by the wire mesh media  65  of filter sections  64 . Over time, the particulate matter may build up in the wire mesh media  65  of the filter sections  64 . If left unchecked, the particulate matter buildup could be significant enough to restrict, or even block the flow of exhaust through openings of the wire mesh media  65 , allowing for pressure within the exhaust system of engine  10  to increase. An increase in the back-pressure of engine  10  could reduce the engine&#39;s ability to draw in fresh air, resulting in decreased performance of engine  10 , increased exhaust temperatures, and poor fuel consumption.  
         [0036]     To prevent the undesired buildup of particulate matter within particulate trap  12 , individual filter sections  64  within a particular filter  30  may be independently regenerated. Regeneration may be periodic or based on a triggering condition. The triggering condition may be a lapsed time of engine operation, a pressure differential measured across particulate trap  12 , or any other condition known in the art.  
         [0037]     Controller  18  may be configured to cause regeneration of the filter sections  64 . When controller  18  determines that regeneration is required (e.g., when a lapse of time corresponding to engine operation is greater than a predetermined value, or when a pressure measured across particulate trap  12  is greater than a predetermined value), controller  18  may cause inner tube  36  to rotate with respect to outer tube  38 . As inner tube  36  rotates within outer tube  38 , a series of openings  56  will align with the single column of openings  46  to allow exhaust to flow through at least one of the filter divisions. However, at least one of openings  46  may be blocked by inner tube  36  to prevent exhaust from flowing through at least one filter division. In the case of reversed exhaust flow, inner and outer tubes  36  and  38  may rotate to allow exhaust to flow out of at least one filter division and to block the flow of exhaust out of at least one filter division.  
         [0038]     When the exhaust flow is blocked from one of the filter divisions, controller  18  may connect the power source via electrical connectors  68  and  69  to at least one filter section  64  of the blocked filter division. Current from the power source (not shown) may cause filter section  64  to heat up above the combustion temperature of the particulate matter trapped in filter section  64 , thereby burning away the buildup of particulate matter.  
         [0039]     Blocking the exhaust flow from regenerating filter section  64  may reduce the energy required for regeneration, because the exhaust flow may remove heat during the regeneration process. Because each filter section  64  within each filter division may be separately regenerated, the magnitude of power required at any one time for regeneration may be low. The low power required for regeneration may allow for low cost, power-generating and power circuit components. In addition, because each filter division undergoing regeneration is substantially fluidly isolated from the other filter divisions within the same particulate trap, the exhaust flowing through non-regenerating filter divisions does not affect the amount of energy required to regenerate the fluidly isolated filter division.  
         [0040]     The modular design, involving independently replaceable filters  30 , may allow for design flexibility as well as low cost maintenance of particulate trap  12 . In particular, because the filters  30  are modular, particulate trap  12  may be easily modified to meet the different restriction and filtering requirements of various power systems. In addition, because the filters are independently replaceable, blocked, damaged, or otherwise unusable filters  30  may be easily and independently replaced at a lower cost than would be required to replace the entire particulate trap  12 .  
         [0041]     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed particulate trap without departing from the scope of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the invention being indicated by the following claims and their equivalents.