Abstract:
A system for treating particulates of an engine&#39;s exhaust is provided. The system comprises a filter configured to collect particulate matter and a device for regenerating the filter. The device comprises a housing, a fuel injector configured to inject fuel, an igniter configured to ignite the injected fuel, and a combustion chamber. The device is characterized in that the cross section of the combustion chamber converges from an inlet to an outlet.

Description:
TECHNICAL FIELD  
       [0001]     The present disclosure is directed to a burner that comprises a combustion chamber with a converging shape. In one embodiment, the combustion chamber comprises a conical shape that converges in diameter from its inlet to outlet. The disclosed burner may be used for various purposes, including the regeneration of a particulate trap within an internal combustion engine&#39;s exhaust system.  
       BACKGROUND  
       [0002]     Internal combustion engines, including diesel engines, gasoline engines, and natural gas engines, for example, generally emit air pollutants. These air pollutants are generally composed of both gaseous matters and particulate matters. Particulate matter from a diesel engine typically includes ash and soot. Soot is composed of carbon particles that were not combusted during the combustion process.  
         [0003]     Over the past several years, engine emission regulations have become increasingly stringent, driving engine manufacturers toward improving and developing new emissions-reducing technologies. Many of these technologies are aimed at minimizing particulate matters emitted from the engine.  
         [0004]     In doing so, some engine manufacturers have developed systems to treat engine exhaust before it enters the environment. Some of these systems employ exhaust treatment devices such as particulate traps to filter particulate matter from the exhaust flow. A particulate trap generally includes a filter material designed to capture particulate matter. After an extended period of use, unfortunately, the filter material may become saturated with particulate matter, thereby hindering the exhaust gas that flows through the particulate trap.  
         [0005]     The collected particulate matter may be removed from the filter material through a process called regeneration—burning. Because soot is composed of unburned hydrocarbons, soot has a propensity for combusting when exposed to oxygen and heat.  
         [0006]     A particulate trap may be regenerated by increasing the temperature of the filter material and the trapped particulate matter above the combustion temperature of the particulate matter, thereby burning away the collected particulate matter. This increase in temperature may be effectuated by various means. For example, some systems may employ a heating element to directly heat one or more portions of the particulate trap (e.g., the filter material or the external housing). Other systems have been configured to heat exhaust gases upstream of the particulate trap.  
         [0007]     Some of these systems that heat the upstream exhaust gases may work by altering one or more engine operating parameters, such as the ratio of air-to-fuel in the combustion chambers. Other systems may heat the exhaust gases upstream of the particulate trap with, for example, a burner disposed within an exhaust conduit leading to the particulate trap.  
         [0008]     In systems that heat exhaust gases upstream of the particulate trap, the heated gases then flow through the particulate trap and transfer heat to the filter material and captured particulate matter. The transferred heat promotes regeneration of the filter by burning the accumulated soot.  
         [0009]     U.S. Pat. No. 5,771,683 to Webb (“Webb”) discloses an auxiliary heat source including a cylindrical flame containment chamber. In particular, FIG. 3 of Webb discloses a relatively cylindrical chamber 42a. The efficiency—or completeness—of the combustion within the combustion chamber is effected by how the flame from the combustor mixes with the exhaust gas entering into the combustor housing. Further, the location of the combustion chamber in the cylindrical combustor housing may cause high flow resistance. This high flow resistance causes high backpressure on the turbine exit of the turbocharger. This high back pressure results in reduced fuel efficiency, lessened transient response, increased thermal loading, reduced high-altitude capability, and loss of engine rating capability, to name a few.  
         [0010]     The disclosed regeneration assembly is directed toward overcoming one or more of the problems set forth above.  
       SUMMARY  
       [0011]     In at least one embodiment, a device configured to at least partially regenerate a particulate filter is provided. The device comprises a housing, a fuel injector configured to inject fuel, and a combustion chamber. The device is characterized in that a cross section of the combustion chamber converges from an inlet to an outlet.  
         [0012]     In at least another embodiment, a system for treating particulates of an engine&#39;s exhaust is provided. The system comprises a filter configured to collect particulate matter and a device configured to at least partially regenerate a particulate filter. The device comprises a housing, a fuel injector configured to inject fuel, and a combustion chamber. The device is characterized in that a cross section of the combustion chamber converges from an inlet to an outlet.  
         [0013]     In yet another embodiment, an aftertreatment system for an engine is provided. The system comprises a filter configured to collect particulates from the engine&#39;s exhaust and a burner configured to regenerate the filter. In this embodiment, the burner comprising a conical combustion chamber.  
         [0014]     In even yet another embodiment, an internal combustion engine is provided. The engine comprises an exhaust system configured to receive engine exhaust, a filter configured to collect particulate matter within the exhaust, a burner configured to regenerate at least some of the particulate matter within the filter, and an engine control module configured to control when the burner regenerates the filter. The engine is characterized in that the burner comprises a conical combustion chamber. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a schematic view of a portion of an embodiment of an internal combustion engine with exhaust system comprising an auxiliary regeneration device;  
         [0016]      FIG. 2  is a cross sectional view of an auxiliary regeneration device comprising a cylindrical combustion chamber in accordance with one particular embodiment;  
         [0017]      FIG. 3  is a cross sectional view of an auxiliary regeneration device comprising a partially conical combustion chamber in accordance with another particular embodiment; and  
         [0018]      FIG. 4  is a cross sectional view of an auxiliary regeneration device comprising a fully conical combustion chamber in accordance with yet another embodiment. 
     
    
     DETAILED DESCRIPTION  
       [0019]     Referring to  FIG. 1 , an engine  10  connected to an auxiliary regeneration device (“ARD”)  20  and particulate filter  30  is shown.  
         [0020]     Regeneration of filter  30  is controlled, at least in part, by engine control module (“ECM”)  40 . ECM  40  may sense engine speed  41 , engine load  42 , exhaust gas temperature  43 , and possibly other engine  10  parameters not shown. In this particular embodiment, ECM  40  also measures filter  30  temperature with temperature sensor  46  and detects whether a flame exists in ARD  20  with flame detection sensor  48 . ECM  40  may then use these measured parameters to generate signals for controlling regeneration, such as ARD  20  fuel control signal  44 , ARD  20  combustion air control signal  45 , and ignition control signal  47  to igniter  49 . The reader should appreciate that igniter  49  may be any device known in the art that may be used to ignite a combustible fuel  53 , such as a glow plug, plasma plug, multi-torch plug, or J-gap spark plug, for example.  
         [0021]     ECM  40  generates ARD  20  fuel control signal  44 , ARD  20  combustion air control signal  45 , and ignition control signal  47  to control regeneration of filter  30 . Signal  44  controls the quantity of fuel  53  injected into ARD  20  provided by fuel supply  50  with fuel supply valve  51 . Signal  45  controls ARD  20  combustion air valve  52 , which controls the amount of pressurized air  101  sent to ARD  20 .  
         [0022]     In this particular embodiment, ARD  20  receives pressurized air  101  in addition to exhaust gas  102 . By providing pressurized air  101  directly to ARD  20 , ARD  20  can regenerate filter  30  at most any engine  10  speed or load, including engine  10  idle. This particular design ensures that ARD  20  receives enough oxygen to ensure combustion at most all engine  10  loads.  
         [0023]     Now referring to  FIG. 2 , an ARD  20  with a cylindrical combustion chamber  240  is depicted.  
         [0024]     ARD  20  comprises a combustor housing  210 , an inlet  211  where exhaust gas  102  enters, a fuel injector  230  for injecting fuel  53 , an igniter  49  for igniting the injected fuel  53 , a pressurized air inlet  271  for receiving pressurized air  101 , a combustor chamber  240 , and a flame stabilizer  250 . As can be seen, combustion chamber  240  is cylindrical and situated within and substantially coaxially with combustor housing  210 . The reader should appreciation, however, that combustion chamber  240  does not necessarily have to be positioned coaxially with combustor housing  210 .  
         [0025]     In this particular embodiment, a flame stabilizer  250  is provided. Flame stabilizer  250  is well known in the art of combustors and provides the function of stabilizing the flame before exiting combustion chamber  240 . The reader should appreciate that any type of flame stabilizer  250  that is known in the art may be used and, in some cases, it may be desirable to not use any flame stabilizer  250 .  
         [0026]     Another function of flame stabilizer  250  is as the flame passes through flame stabilizer  250 , the flow of gases accelerates and forms a high velocity flame jet in zone two  243 . The high jet momentum improves the turbulent mixing between the flame jet and the oxygen in the exhaust gas, thus enabling zone two  243  combustion to proceed more rapidly and more completely.  
         [0027]     In this particular embodiment, an air swirler  244  is also depicted. Air swirler  244  aids in mixing of combustion air  101  with fuel  53  before the mixture is ignited. The reader should appreciate that air swirler  244  is generally known to one skilled in the art and that various air swirlers  244  may be used to achieve mixing of air  101  with fuel  53 . Furthermore, although  FIGS. 2-4  depict an ARD  20  with flame swirler  244 , the reader should also appreciate that ARD  20  may also work without air swirler  244 .  
         [0028]     During rich-burn combustion within chamber  240 , only a fraction of combustion air from pressurized air  101  required for complete combustion is supplied to combustion chamber  240 . Accordingly, in zone one  242 , there is excess fuel  53  during rich-burn combustion. This rich-burn combustion in zone one  242  within primary combustion chamber  240  results in the oxidation of fuel  53  into carbon monoxide, H 2 , and some other unburned hydrocarbon products. Combustion continues in zone two  243  when the incomplete combustion product from zone one  242  is discharged into combustor housing  210 , where it is mixed with O 2  from exhaust gas  102 . The efficiency—completeness—of the combustion in zone two  243  is significantly effected by how the flame jet from zone one  242  is mixed with exhaust gas  102  entering into combustion housing  210 .  
         [0029]     Due to the constrain of the ARD  20  packaging, as well as the mixing requirements of the flame jet and the exhaust gas  102  jet, primary combustion chamber  240  within combustor housing  210  is often positioned directly in the path of exhaust gas  102  and inlet  211 . Locating combustor chamber  240  so that it intersects with inlet  211  and flow  102  generally increases the flow resistance of exhaust gas  102 . This increased flow resistance results in increased backpressure on the exit of turbine  100 , thus resulting in unacceptable performance penalties to engine  10 . Some of these performance penalties include a fuel consumption penalty, deteriorated transient response, increased thermal loading, reduced altitude capability, and loss of rating capability.  
         [0030]     The conical combustion chambers  340  and  440  described in  FIGS. 3 and 4  reduce the flow resistance of exhaust gas  102  within ARD  20 .  
         [0031]     Referring now to  FIG. 3 , an ARD  20  comprising a partially conical combustion chamber  340  is depicted. As can be seen, combustion chamber  340  comprises two sections, first section  341  and second section  342 . Second section  342  comprises a substantially cylindrical chamber with a constant diameter along its length. First section  341 , on the other hand, comprises a chamber with a converging diameter, which gives second section  342  a conical shape. Together, sections  341  and  342  give combustion chamber  340  a partially conical construction, which minimizes exhaust  102  flow resistance.  
         [0032]     Referring now to  FIG. 4 , an ARD  20  comprising a fully conical combustion chamber  440  is depicted. As can be seen, ARD  20  comprises a combustion chamber  440  with a shape that converges from its inlet to its outlet. In this embodiment, the diameter of chamber  440  converges along its entire length, thus giving chamber  440  a conical shape.  
         [0033]     Although  FIGS. 3 and 4  depict either a partially conical-shaped combustion chamber  340  or a fully conical-shaped combustion chamber  440 , the reader should appreciate that any combustion chamber  240  with a decreasing cross-sectional area may alternatively be used to achieve substantially similar results. For example, the combustion chamber  240  does not necessarily require a circular shape, thus giving it a cylindrical or conical shape. Instead, for example, the combustion chamber may have a square, rectangular, triangular, etc., cross sectional shape.  
         [0034]     The partially conical combustion chamber  340  and fully conical combustion chamber  440  are depicted as being attached with flame stabilizers  250 . Although the depicted embodiments show the presence of flame stabilizers  250 , the reader should also appreciate that ARD  20  may be used without stabilizers  250 . Omitting flame stabilizers  250  from the design may reduce the cost of manufacture while providing for reduced exhaust gas  102  backpressure—for a combustion chamber  240 ,  340 , and  440  of identical design, that is.  
       INDUSTRIAL APPLICABILITY  
       [0035]     Referring again to  FIG. 1 , a brief description of the operation of engine  10  with ARD  20  will be made.  
         [0036]     In operation, fresh air  60  enters compressor  70 , where it is pressurized. From compressor  70 , pressurized air  101  is then either sent to combustion air valve  52  or to intake manifold  80  of engine  10 .  
         [0037]     If sent to valve  52 , pressurized air  101  will be utilized—in part—to aid in combustion of fuel  53  in ARD  20 . If pressurized air  101  is sent to intake manifold  80 , pressurized air  101  will aid in providing combustion air within internal combustion engine  10 .  
         [0038]     If the pressurized air was sent to intake manifold  80 , once air  101  takes part in the combustion process of engine  10 , exhaust gas  102  will enter exhaust manifold  90 . Exhaust  102  will be pressurized as a result of the combustion process and will be used to drive turbine  100 . In this embodiment, pressurized exhaust  102  drives turbine  100 , which is connected to compressor  70  for providing the energy required to pressurize fresh air  60 .  
         [0039]     Once exhaust  102  exits turbine  100 , exhaust  102  enters ARD  20 , where, in combination with pressurized air  101 , it is used to provide the oxygen necessary for aiding in the combustion of fuel  53  in ARD  20 .  
         [0040]     In this particular embodiment, ECM  40  receives engine speed signal  41 , engine load signal  42 , and exhaust gas temperature signal  43  from engine  10 . ECM  40  also determines whether a flame exists in ARD  20  via flame detection sensor  48  and the temperature of filter  30  via temperature sensor  48 . ECM  40  uses these parameters to generate control signal  44  for fuel supply valve  51 , control signal  45  to combustion air valve  52 , and control signal  47  for igniter  49 . Once ARD  20  generates combustion of fuel  53 , the heated regeneration air  290  is expelled towards filter  30 . The heated regeneration air  290  then facilitates burning of the soot and unburned carbon particles in filter  30 , thereby regenerating filter  30 . By controlling the amount of combustion air  101  and fuel  53  that is sent to ARD  20 , as well as ignition of igniter  49 , ECM  40  can precisely control regeneration of filter  30 .  
         [0041]     It will be apparent to those having ordinary skill in the art that various modifications and variations can be made to the disclosed regeneration assembly without departing from the scope of the invention. Other embodiments of the invention will be apparent to those having ordinary skill 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.