Patent Publication Number: US-2012036843-A1

Title: Air filter aspiration and aspiration fan drive for use with exhaust treatment

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to copending U.S. provisional application entitled, “Air Filter Aspiration and Exhaust Treatment and Aspiration Fan Drive,” having Ser. No. 61/372,780, filed Aug. 11, 2010, which is entirely incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure is generally related to diesel engines and, more particularly, is related to a system and method for aspirating an air filter assembly of a diesel engine, which uses exhaust treatment. 
     BACKGROUND 
     Utility vehicles, such as agricultural tractors, and plant machinery are often required to work in dusty environments. In order to avoid dust entering the air intake of an internal combustion engine of such a vehicle or machine, it is known to filter intake air upstream of the engine. 
     A typical air intake system includes, in airflow order, a pre-filter and a main filter. The pre-filter removes larger dust particles from the intake air, and then the main filter removes smaller particles. Without the pre-filter, the main filter tends to clog in an unacceptably short time. 
     The particles collected by the pre-filter are typically removed by scavenging vacuum pressure that is created from engine exhaust. However, reliance on an engine exhaust system to provide such vacuum pressure can be problematic due to various factors, such as structural complexity and back pressure being too high to accommodate additional requirements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a schematic diagram of an example embodiment of a tractor with a diesel engine assembly. 
         FIG. 2  is a schematic diagram of an example embodiment of an exhaust treatment system. 
         FIG. 3  is a perspective view of an example embodiment of an intake treatment system. 
         FIG. 4  is a flow chart depicting an example embodiment of a method for operating a diesel engine. 
         FIG. 5  is a perspective view of another example embodiment of a diesel engine assembly. 
         FIG. 6  is a perspective view showing detail of an example embodiment of an aspiration fan drive. 
         FIG. 7  is a perspective view of selected components of an example embodiment of an aspiration fan drive. 
         FIG. 8  is an assembly view of an example embodiment of an aspiration fan drive. 
         FIG. 9  is a flow chart depicting another example embodiment of a method for operating a diesel engine. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Overview 
     An example embodiment of a system includes a diesel engine with an intake and an exhaust. An exhaust treatment system communicates with the exhaust and treats combustion products of the engine. An intake treatment system communicates with the intake and includes an air filter assembly that removes particles from a flow of air that is provided to the engine. An aspiration fan assembly includes a fan mechanically driven by the engine to produce scavenging vacuum pressure, which is applied to the air filter assembly to remove particles collected in the air filter assembly. 
     Detailed Description 
     As will be described in more detail below, scavenging vacuum pressure can be provided for aspirating an air filter of a diesel engine that implements exhaust treatment (e.g., Selective Catalytic Reduction (SCR)). In various embodiments, this is accomplished by an idler pulley that engages a drive belt of the engine, and which imparts rotational speed to a fan that produces the scavenging vacuum pressure. Notably, rotational speeds of the fan in excess of 8,000 RPM can be achieved. 
     The use of various exhaust treatment technologies limit the ability to use exhaust pressure to provide various functions, such as scavenging vacuum pressure. In contrast to the prior art, the use of an engine driven idler pulley to produce scavenging vacuum pressure enables the use of exhaust treatment with an aspirated air filter since the idler pulley does not draw from or rely on exhaust pressure to function. Though certain embodiments described herein achieve these and/or other benefits, it should be understood in the context of the present disclosure that all of these benefits may not necessarily be provided through a single embodiment or realized in all embodiments described herein. 
     As shown in  FIG. 1 , a tractor  100  includes an engine compartment  102 , a cab  104  and wheels, of which wheels  106  and  108  are depicted. A diesel engine assembly  110  is housed within engine compartment  102 , and includes intake treatment system  112 , engine  114  and exhaust treatment system  116 . 
     Intake treatment system  112  is positioned along the flow path of intake  118 , which provides a flow of air to engine  114 . Exhaust treatment system  116  is positioned along the flow path of exhaust  120 , which directs combustion products from engine  114 . 
     In operation, intake treatment system  112  removes particles (e.g., dust) from a flow of air that is provided to engine  114  via intake  118  to facilitate combustion. Thereafter, combustion products are directed to exhaust treatment system  116 , which performs a catalytic reaction with the combustion products to reduce undesirable emissions. 
     In  FIG. 2 , exhaust treatment system  116  is shown to incorporate a catalyst  122 , a controller  124  and a supply  126  of additives. Specifically, catalyst  122  includes an SCR catalyst positioned within exhaust  120  along the flow path of the combustion products. The combustion products are represented by arrow A. Notably, exhaust treatment system  116  functions as means for performing SCR on combustion products of a diesel engine. 
     An injector  128  is fluidicly coupled to supply  126 . Injector  128  selectively dispenses additives (e.g., DEF) into exhaust  120 , with the dispensed additives being represented by arrow B. Notably, the additives are dispensed within exhaust  120  and upstream of catalyst  122  to stimulate a reaction that is known to reduce various emissions such as NOx. Dispensing of the additives is performed responsive to signals from controller  124 , which monitors various system parameters. By way of example, controller  124  can monitor exhaust temperature via sensor  130 . Remaining products, represented by arrow C, are directed to atmosphere with exhaust  120 . 
     It should be noted that use of exhaust treatment system  116  increases the backpressure on diesel engine assembly  110  to such an extent that exploitation of the flow of combustion products to produce vacuum pressure may not be practicable. Notably, such vacuum pressure can be used for scavenging particles from an air filter assembly that, if not removed, could reduce the ability of the assembly to provide an appropriate volume of clean air for combustion. In this regard,  FIG. 3  depicts intake treatment system  112  (in greater detail), which does not rely on engine exhaust for producing scavenging vacuum pressure. 
     As shown in  FIG. 3 , intake treatment system  112  communicates with intake  118 . Specifically, intake treatment system  112  includes an air filter assembly  132  that removes particles from an intake flow of air represented by arrow D. Air filter assembly  132  then provides a flow of filtered air (represented by arrow E) to engine  114  via intake  118 . As such, air filter assembly  132  functions as means for collecting particles from an intake flow of air for the diesel engine. 
     An aspiration fan assembly  134  also is depicted in  FIG. 3 . Aspiration fan assembly  134  incorporates a fan  136  that is mechanically driven by engine  114  (not shown in  FIG. 3 ) to produce scavenging vacuum pressure. The scavenging vacuum pressure is applied to air filter assembly  132  by aspiration conduit  138  to remove particles collected in air filter assembly  132  from the intake flow of air. That is, the particles are drawn away from air filter assembly  132 , through aspiration conduit  138 , and toward fan  136 . Thus, aspiration fan assembly  134  functions as means for removing the particles collected using scavenging vacuum pressure and without adding exhaust restriction to the system. 
     An example embodiment of a method for operating a diesel engine is depicted in  FIG. 4  that includes collecting particles from an intake flow of air (block  140 ). In block  142 , the particles that were collected are removed using scavenging vacuum pressure and without adding exhaust restriction. Then, as shown in block  144 , combustion products of the diesel engine are treated. By way of example, SCR can be used. 
       FIG. 5  is a perspective view of another example embodiment of a diesel engine assembly  110  that includes an intake treatment system  112 , an engine  114  and an exhaust treatment system  116 . Intake treatment system  112  is positioned along the flow path of an intake  118 . Exhaust treatment system  116  is positioned along the flow path of exhaust  120  and includes an SCR catalyst  122  for reacting with combustion products. 
     Intake treatment system  112  of  FIG. 5  incorporates an air filter assembly  132  that removes particles from an intake flow of air. Specifically, air filter assembly  132  includes a pre-filter  146  positioned upstream of a main filter  148 . Pre-filter  146  removes particles that are drawn into air filter assembly  132 . Pre-filter  146  collects these particles until scavenged as will be described later. As such, pre-filter  146  functions as means for pre-filtering the flow of air. 
     Main filter  148  receives pre-filtered air from pre-filter  146  and removes smaller particles from the air flow. Air filter assembly  132  then provides a flow of filtered air to engine  114  via intake  118 . Thus, main filter  148  functions as means for filtering the flow of air. 
     Aspiration fan assembly  134  incorporates a fan (not shown in  FIG. 5 ) that is mechanically driven by engine  114  to produce scavenging vacuum pressure. The scavenging vacuum pressure is applied to air filter assembly  132  by aspiration conduit  138  to remove particles collected in air filter assembly  132 . In particular, aspiration conduit  138  applies the scavenging vacuum pressure to pre-filter  146  to draw particles collected by the pre-filter into the aspiration conduit such that efficiency of air filter assembly  132  is maintained. 
     A more detailed view of diesel engine assembly  110  is provided by  FIG. 6 . As shown in  FIG. 6 , engine  114  includes various accessories, such as an alternator  150  that is driven by an engine drive belt  152 . Notably, engine drive belt  152  engages about and extends between a first pulley  154 , which is coupled to alternator  150 , and a second pulley  156 , which is a drive pulley. Aspiration fan assembly  134  includes a compound idler pulley  158 , an outer surface of which engages an outer surface of engine drive belt  152  to rotate compound idler pulley  158 . 
     As shown in  FIGS. 6-8 , compound idler pulley  158  includes a first pulley stage  160  and a second pulley stage  162 , with the first pulley stage being positioned to engage engine drive belt  152 . Second pulley stage  162  drives a fan  164  ( FIG. 7 ) of aspiration fan assembly  134  responsive to rotation of first pulley stage  160 . 
     As shown most clearly in  FIG. 7 , first pulley stage  160  and second pulley stage  162  are coaxial and form an integral component. So configured, rotation of first pulley stage  160  results in rotation of second pulley stage  162 . Additionally, second pulley stage  162  exhibits a longer radius (R 2 ) than the radius (R 1 ) of first pulley stage  160  such that R 2 &gt;R 1 . Thus, compound idler pulley  160  functions as a means for converting rotational motion to higher speed rotational motion. 
     Also depicted in  FIG. 7  are fan pulley  166  and aspiration drive belt  168 . Aspiration drive belt  168  engages about and extends between fan pulley  166  and second pulley stage  162 . Notably, second pulley stage  162  exhibits a longer radius (R 2 ) than the radius (R 3 ) of fan pulley  166  such that R 2 &gt;R 3 . In some embodiments, second pulley stage  162  exhibits a longer radius (R 2 ) than the radius (R 1 ) of first pulley stage  160 , which also exhibits a longer radius than the radius (R 3 ) of fan pulley  166  (i.e., R 2 &gt;R 1 &gt;R 3 ). So configured, aspiration fan assembly  134  is capable of driving fan  164  at speeds in excess of 8,000 RPM. Thus, fan pulley  166  is also capable of functioning as a means for converting rotational motion to higher speed rotational motion. 
     The assembly view of  FIG. 8  depicts several components in greater detail. In this regard, compound idler pulley  158  is secured to an engine mount  170  by a bolt  172  that passes, in sequence, through spacer  174 , compound idler pulley  158 , bearing  176 , retaining ring  178  and spacer  180 . Also depicted is fan support  182  that mounts stator  184 , which supports axle  186  ( FIG. 7 ) of fan  164 . Stator  184  also secures fan  164  to housing  188 , which surrounds fan  164  and serves as a connector for aspiration conduit  138 . An evacuation port  190  is located at base of aspiration conduit  138  adjacent to housing  188  for expelling particles scavenged from pre-filter  146 . 
       FIG. 9  is a flow chart depicting another example embodiment of a method for operating a diesel engine that includes pre-filtering intake air to remove larger particles (block  190 ), and then filtering the air to remove smaller particles (block  192 ). In block  194 , mechanically drive a fan to produce the scavenging vacuum pressure, which is then applied to remove particles that were collected during pre-filtering (block  196 ). Notably, the fan is mechanically driven in a manner that does not add exhaust restriction. Then, as shown in block  198 , SCR is performed on combustion products of the diesel engine. 
     It should be emphasized that the above-described embodiments, particularly, any “preferred” embodiments, are merely possible examples of implementations, merely set forth for a clear understanding. Many variations and modifications may be made to the above-described embodiments without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.