Patent Application
20100319329
The subject invention relates to a fuel-fired burner for a mobile application, and more particularly to a vehicle exhaust system utilizing a thermal regenerator or enhancer that has a mixer.
Exhaust systems are widely known and used with combustion engines. Some exhaust systems utilize a thermal regenerator (TR) or a thermal enhancer (TE). A TR is an active unit that enables regeneration of a diesel particulate filter (DPF) as well as providing exhaust thermal management under various operating conditions. A TE is a partial range burner supporting active DPF regeneration or exhaust thermal management. The TE elevates the exhaust temperature of exhaust gas to enable regeneration of a DPF under low temperature conditions or to improve the efficiency of NOx reduction catalysts.
The TR and TE include a combustor unit that includes an air supply line, a fuel supply line and an igniter unit. This traditional configuration is disadvantageous from a cost and complexity perspective. Airless TRs and TEs are desirable because they reduce cost and are less complex due to the elimination of the air supply components. However, airless TRs and TEs have significantly larger fuel droplet sizes, which are difficult to ignite and produce more hydrocarbons.
A component assembly includes a combustor that comprises a fuel-fired burner for a mobile application. In one example, the fuel-fired burner comprises one of a thermal regenerator or airless thermal enhancer operating with airless injection and which is configured to regenerate a particulate filter. A mixer is positioned within the thermal regenerator or enhancer to improve ignition by reducing fuel droplet size. A low pressure region is also created behind the mixer which further assists the ignition process.
In one example, at least one fuel nozzle supplies fuel to the combustor and an igniter ignites fuel sprayed from the fuel nozzle. The mixer is positioned downstream of the fuel nozzle and upstream of the igniter and operates to reduce fuel droplet size as fuel flows through the mixer. Fuel from the fuel nozzle is solely mixed with existing exhaust gases for ignition without requiring an additional atomization air supply.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
The exhaust component assembly 10 includes a housing 14 defining an internal cavity 16 and an internal wall structure 18 that defines a combustion chamber 20. The housing 14 includes an exhaust gas inlet 22 and an exhaust gas outlet 24. Exhaust gases generated from an engine E flows through any upstream exhaust components 26 to the exhaust gas inlet 22. Exhaust gases flow through the exhaust component assembly 10 to the exhaust gas outlet 24 and then on to downstream exhaust system components 28.
At least one fuel nozzle 30 is supported by the housing 14 to inject/spray fuel from a fuel supply 32 into the combustion chamber 20. The fuel is sprayed into existing exhaust gases within the combustion chamber and an igniter 34 (
The exhaust component assembly 10 comprises a fuel-fired burner. In one example, the fuel-fired burner comprises one of an thermal regenerator (TR) or thermal enhancer (TE). A TR is an active unit that enables regeneration of a diesel particulate filter (DPF) as well as providing exhaust thermal management under various operating conditions. A TE is a partial range burner supporting active DPF regeneration or exhaust thermal management. The TE elevates the exhaust temperature of exhaust gas to enable regeneration of a DPF under low temperature conditions or to improve the efficiency of NOx reduction catalysts. Further, a TR comprises a combustor system that operates overall an entire engage map while a TE typically operates only in low and medium speed load ranges.
The igniter 34 ignites fuel droplets sprayed by the fuel nozzle 30 in one of the TR or TE to increase temperatures such that a particulate filter PF can be regenerated or a NOx reduction catalyst can be heated up. Ignition of the fuel accomplished without any type of additional atomization air supply to the combustor 12. This provides reduced cost and complexity of the component assembly.
Examples of different mixers 40 are shown in
It should be understood that the examples set forth in
Exhaust gas enters through the inlet 22 and hits an outer surface of the internal wall structure 18, which include a plurality of openings 84 that allow exhaust gas to enter the combustion chamber 20. The mixer 40 mixes the exhaust gas and the fuel droplets to produce the mist that is ignited by the igniter 34. As discussed above, this occurs without any additional air supply to the combustion chamber 20. Exhaust gas then flows from the combustion chamber, and/or through openings 86 in the shroud 82, to the exhaust gas outlet 24.
In any of the configurations discussed above, the mixer 40 serves to significantly reduce the size of fuel droplets within the combustion chamber 20. These smaller droplets are more easily mixed with the exhaust gases, and are therefore easier to ignite. In addition, by positioning the mixer 40 downstream of the fuel nozzle 30 and upstream of the igniter 34, a lower pressure region is created at the upstream side of the mixer that also improves ignition and flame stability.
Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
