Abstract:
Aspects provide for an engine and an aftertreatment system coupled to the engine and configured to treat an exhaust stream from the engine. The engine may be incorporated into a mobile piece of equipment (e.g., a truck). A fairing may be shaped to improve air flow during motion by reducing air resistance created by the aftertreatment system.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates reducing emissions from engines. 
       BACKGROUND 
       [0002]    Transport of goods may require the use of engines, which may emit pollution such as hydrocarbons, oxides (CO, CO2, NOx), particulate matter, and the like. In some cases, reducing an emission of one pollutant may increase emission of another pollutant. Minimizing an integrated impact of pollution may require the optimization of emission of a large number of different pollutants. 
       SUMMARY OF THE INVENTION 
       [0003]    This paper incorporates by reference U.S. patent application Ser. Nos. 12/183,917 (now U.S. Pat. No. 7,981,375), 13/171,489, 12/824,070, and 12/756,987. Various aspects provide for reducing pollution emitted during transportation. A combination of reduced CO2 emission and reduced criteria pollutant emission may result from an aftertreatment system and/or operation methods that combine to reduce integrated emission. 
         [0004]    A tractor may include an engine and an aftertreatment system coupled to the engine. The aftertreatment system may treat the exhaust stream from the engine. Treatment may include reducing a concentration of one or more contaminants in the exhaust stream. The tractor may include a fairing, which may be shaped to improve a flow of air past the tractor, and more particularly past at least a portion of the aftertreatment system. The fairing may contain or otherwise be shaped to modify the airflow around at least a portion of the aftertreatment system in a manner that reduces air resistance. 
         [0005]    In some cases, the fairing and portion of the aftertreatment system contained by the fairing are disposed above a cab of the tractor. For some tractors (e.g., a class 8 truck), a fairing and aftertreatment system may be sized and shaped to improve air flow past a trailer (e.g., an intermodal container trailer) configured to be towed by the tractor. The fairing may reduce fuel consumption of the engine, as compared to a similar tractor without the fairing, by at least 0.5%, or even 1% at a speed of 100 km/hr. The fairing and may reduce fuel consumption by at least 3% at a speed of 120 km/hr as compared to a similarly configured tractor without the fairing. Some embodiments may reduce fuel consumption by over 2% at 75 mph. 
         [0006]    The aftertreatment system may include at least one of a DOC, DPF, SCR, SNCR, LNT, ammonia slip, and other reactors. In some cases, a reactor volume (e.g., a substrate volume) may be greater than 2, 3, 5, 7, 10, 15 or even 20 times a displacement of the engine. In some embodiments, an aftertreatment having reactor volume greater than 50 liters, 100 liters, 200 liters, or even 300 liters may be disposed above a cab of a tractor behind a fairing configured to improve air flow past the aftertreatment system. 
         [0007]    Some aftertreatment systems (e.g., disposed above a cab) may be removably connected in a manner that provides for changing out a reactor from above (e.g., with a crane, lift, and the like). In some cases, an aftertreatment system may be disposed above a deck of a boat, and may include an exhaust tube having a valve (e.g., a flap) configured to seal an interior of the aftertreatment reactor during capsize. A large, sealed aftertreatment, disposed above the deck, may provide for “self righting” of a capsized boat. 
         [0008]    An aftertreatment may include one or more portions, including first, second, third, fourth, or even fifth portions. In some cases, an aftertreatment system includes a DOC, DPF, SCR and ammonia slip reactor. Some portions may be disposed within a body of the tractor. A DPF may have a substrate volume greater than three, five, or even 10 times the engine displacement. An SCR may have a substrate volume greater than three, five, or even 10 times the engine displacement. An aftertreatment system may include a muffler. 
         [0009]    A fairing may include a vent, which may be operable to allow air to pass through the fairing an interact with the aftertreatment system. In some operation, a reactor temperature is determined (e.g., measured), and the reactor is cooled by opening a valve in the fairing to allow air to pass through and cool the reactor. In one example, overtemperature conditions during regeneration of a DPF may be mitigated by opening one or more vents in a fairing containing the DPF. 
         [0010]    In some cases, a fairing and aftertreatment system may be sized and shaped to match a locomotive, which may have an engine displacement of over 1000 liters. An aftertreatment system may be disposed on a roof of a construction tractor (e.g., a backhoe, bulldozer, and the like). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  illustrates an exemplary embodiment. 
           [0012]      FIG. 2  illustrates an exemplary embodiment. 
           [0013]      FIGS. 3A-3C  illustrate various views of a select embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Various embodiments provide for combining an aftertreatment system and an aerodynamic fairing, which may enable the location of an aftertreatment system (e.g., a large aftertreatment system) in a wide range of places on a tractor.  FIG. 1  illustrates an exemplary embodiment. Tractor  100  may include a truck, a train, a boat, a car, and/or another motive device configured to move a load (e.g., goods, people). In some embodiments, tractor  100  may be coupled with a trailer (e.g., trailer  102 ) to form a tractor-trailer. In some embodiments, tractor  100  may include an integral bed and/or compartment (not shown) configured to carry a load. Tractor  100  may include a heavy duty normal control truck. 
         [0015]    Tractor  100  may include a variety of structural components (chassis, suspension, panels, fenders, bumpers, compartments, and the like), described herein as a body  110 . Body  110  may house an engine  120 , which may be a direct injection engine, an indirect injection engine, a compression induced ignition engine, a spark ignited engine, a diesel engine, a gasoline engine, an alcohol engine, a turbine, and the like. Engine  120  may be configured to move tractor  100  (e.g., by transmitting power to turn wheels  104 ). Engine  120  may be coupled (e.g., with one or more tubes  130 ) to aftertreatment  140 . Aftertreatment  140  may comprise a system configured to reduce a concentration of one or more contaminants in an exhaust stream from engine  120 . Exemplary contaminants include criteria pollutants such as particulate matter (PM), NOx, CO, hydrocarbons, climate forcing contaminants (e.g., CO2), and the like. 
         [0016]    At least a portion of aftertreatment  140  may be shielded by, contained in, or otherwise “made aerodynamic” by fairing  150 . Fairing  150  may be shaped to improve the aerodynamics of tractor  100  (e.g., reduce the aerodynamic drag associated with a flow of air past tractor  100  and/or trailer  102 ). Fairing  150  may be shaped to guide air around (e.g., at least the upstream face of) aftertreatment  140 . Fairing  150  may substantially contain at least a portion of aftertreatment  140 , and in some cases may be integrated with aftertreatment  140 . In some embodiments, a first portion of aftertreatment  140  (e.g., a DOC) is external to fairing  150  (e.g., adjacent to engine  120 ), and a second portion of aftertreatment  140  (e.g., a DPF) is contained within fairing  150 . Exhaust gases may exit aftertreatment system  140  via exhaust  160 , which may be integrated with fairing  150 . 
         [0017]    In some embodiments, a portion of aftertreatment  140  is disposed substantially within body  110  (e.g., close coupled to engine  120 ). In some embodiments, a portion of aftertreatment  140  is disposed external to body  140  (e.g., attached to a chassis or frame member). A first portion may be disposed substantially within body  110 , a second portion may be disposed outside body  110 , and a third portion may be disposed behind fairing  150 . 
         [0018]    Aftertreatment system  140  may include one or more reactors, such as a Diesel Oxidation Catalyst reactor, a NOx trap reactor (e.g., a Lean NOx Trap), a selective catalytic reduction (SCR) reactor, a particulate filter (e.g., a diesel particulate filter, DPF), an ammonia slip reactor, and/or a selective non-catalytic reduction (SNCR) reactor. In some cases, a reactor volume may be associated with a volume of a substrate within a reactor. In some cases, a reactor volume may be associated with a volume of a “canned” reactor (e.g., a substrate contained within a sealed container having an inlet and outlet through which exhaust passes. A reactor volume may be more than twice as large as a displacement volume of an engine  120  associated with tractor  100 . In some cases, reactor volume is at least three times, five times, or even ten times larger than the engine displacement. An aftertreatment system may have a volume (e.g., a reactor volume) greater than 40 gallons, 55 gallons, 100 gallons, or even 200 gallons. In some cases, a DPF reactor has a size greater than five times the engine displacement. In some cases, an SCR reactor has a size greater than three times the engine displacement. An exemplary reactor sized for a 10 liter engine may have a volume of at least 30 liters, including at least 50 liters, or even at least 100 liters. 
         [0019]    In some cases, an aftertreatment  140  may include a DOC and DPF combined as a single unit (e.g., a DOC upstream of a DPF), which may be contained within fairing  150 . An aftertreatment  140  contained by fairing  150  may include an SCR reactor, and may also include an ammonia slip reactor. A first portion of aftertreatment  140  may include a DOC close to engine  120  and a second portion of aftertreatment  140  a DPF reactor and SCR reactor within fairing  150 . A first portion of aftertreatment  140  may include a DOC close to engine  120 , a second portion of aftertreatment  140  may include a DPF after the DOC and before fairing  150  (e.g., behind a cab of tractor  100 ) and a third portion may include an SCR reactor contained by fairing  150 . The position of various reactors (e.g., DOC, DPF, SCR) in the gas flow direction may be changed as desired. In some cases, a DOC, DPF and SCR are contained within fairing  150 . 
         [0020]    For some tractors  100 , fairing  150  and at least a portion of aftertreatment system  140  may be disposed over body  110  (e.g., over the cab of tractor  100 ). A shape and height of the fairing  150  may be matched to an expected height of trailer  102 , e.g., in a manner that reduces aerodynamic drag as compared to a tractor not having the fairing. In an exemplary case, a fairing  150  (e.g., for a US class 8 truck) may be somewhat wedge shaped (possibly with smoothed corners and/or convex or concave surfaces) and have a front edge disposed just above a windshield height, rising to a back edge having a height close to that of a trailer to be coupled to the truck, which may create a large “leeward” volume within which aftertreatment  140  may be disposed. An “over the cab” aftertreatment  140  may have a volume that is larger than that of prior aftertreatment systems, whose dimensions may be constrained by space and geometry (e.g., under-chassis size constraints). By sheltering a large aftertreatment  140  behind fairing  150 , the benefits of a large aftertreatment (e.g., high soot storage capacity, high ash storage capacity, high surface area) may be achieved without reducing aerodynamic efficiency and/or being constrained by typical “on-chassis” installation locations. In some cases, an ash storage capacity of a DPF reactor associated with aftertreatment  140  may provide for greater than 100,000 miles of operation, greater than 500,000 miles of operation, or even greater than 1E6 miles of operation. 
         [0021]    In some cases, a fuel consumption of tractor  100  having fairing  150  and contained aftertreatment system  140  may be reduced by more than 0.5%, 1%, 3%, or even 5% (e.g., at 100 km/hr) as compared to a tractor not having fairing  150 . In some embodiments, the contained portion of aftertreatment  140  may be removably attached to exhaust tubes  130 . In some cases, aftertreatment  140  and fairing  150  are connected, disposed above the cab of tractor  100 , and may be removed by hoisting from above. In certain cases, at least one exhaust tube  130  may be removably coupled to aftertreatment  140  in a manner that provides for de-ashing a substrate associated with aftertreatment  140  (e.g., an aftertreatment  140  having a particulate filter). A coupling  132  may provide fluidic communication with exhaust  160  via at least a portion of aftertreatment  140 . In some cases, a de-ashing apparatus may attach to exhaust  160  and coupling  132  to de-ash or otherwise regenerate at least a portion of aftertreatment  140 . In some embodiments, an aftertreatment  140  may be located above a cab (e.g., of a tractor, bulldozer, backhoe, and the like) of a low speed or even stationary device. An “above cab” location may provide for removing an aftertreatment  140  to an area that does not block the view of an operator. 
         [0022]      FIG. 2  illustrates an exemplary embodiment. Tractor  200  may include body  210 , which may be configured as a “cab over engine” and/or forward control truck. Tractor  200  may be removably attachable to a trailer  202 . In some embodiments, tractor  200  may be connected to trailer  202  as an integrated unit (e.g., as a box truck). In some embodiments, a fairing may contain a compressor (e.g., an air conditioner compressor). 
         [0023]      FIGS. 3A-3C  illustrate various views of a select embodiment.  FIG. 3A  illustrates a first side view of a fairing  300  and integrated aftertreatment system  310 .  FIG. 3B  illustrates a rear view, and shows an exemplary configuration for exhausts  160 .  FIG. 3C  illustrates a front view, and shows an optional vent  320 . In some embodiments, one or more vents  320  may be disposed in a fairing (e.g., fairing  300 ). A vent  320  may be adjustable (e.g., to vary from closed to open) to allow a desired amount of air to flow through fairing  300 . In some embodiments, cold operation (e.g., while aftertreatment system  310  is cold) may include operating vent  320  in a closed position, and hot operation may include operating vent  320  in an open position. In some implementations, vent  320  may be opened during a period of time during which aftertreatment system  310  (e.g., having a filled particulate filter) is regenerated to burn of accumulated particulate matter). In some cases, vent  320  may be in communication with one or more powertrain control components (e.g., an engine control unit, ECU), and may be operated by the ECU to vary air flow through fairing  300  in concert with the operation of other engine controls. Vent  320  may include a plurality of vents (e.g., a first vent  320  on a front side of fairing  300  and a second vent  322  on a back side of fairing  300 ). One or both of the vents may be adjustable. An aftertreatment  140  may include a heat exchanger (e.g., for cooled exhaust gas recirculation, EGR). An heat exchanger may be disposed with vent  320  in a manner that allows air flow through vent  320  to control an amount of air flowing through the heat exchanger. Certain embodiments may include sensors (e.g., to sense temperature, contaminant concentration, soot loading, pressure, engine conditions, position, and the like) and/or actuators (e.g., to open/close valves). Some embodiments may include a processor, memory, and a computer readable storage medium having embodied thereon a program executable by the processor to perform a method. 
         [0024]    The above description is illustrative and not restrictive. Many variations of the invention will become apparent to those of skill in the art upon review of this disclosure. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.