Tailpipe exhaust gas mixer and method

Abstract

An engine system ( 100 ) includes an internal combustion engine ( 101 ) connected to an exhaust system ( 102 ). A portion ( 103 ) of the exhaust system ( 102 ) is connected to the internal combustion engine ( 101 ), and an additional portion ( 111 ) of the exhaust system ( 102 ) is connected to a vehicle and includes a tailpipe ( 123 ). An after-treatment system ( 105, 109 ) is connected to the engine ( 100 ) located between the internal combustion engine ( 101 ) and the tailpipe ( 111 ). A mixer ( 200 ) is located between a first segment of the tailpipe ( 202 ) and a second segment of the tailpipe ( 204 ). The mixer ( 200 ) is arranged to mix a flow of exhaust gas ( 214 ) from the first segment of the tailpipe ( 202 ) with a flow or air ( 218 ) to yield a mixture, and to route the mixture into the second segment of the tailpipe ( 204 ).

1 . An engine system, comprising:
 an internal combustion engine connected to an exhaust system, wherein a portion of the exhaust system is connected to the internal combustion engine, and an additional portion of the exhaust system is connected to a vehicle and includes a tailpipe;   an after-treatment system connected to the vehicle, wherein the after-treatment system is connected to the exhaust system and disposed between the internal combustion engine and the tailpipe;   a mixer that is disposed between a first segment of the tailpipe and a second segment of the tailpipe, wherein the mixer is arranged to mix a flow of exhaust gas from the first segment of the tailpipe with a flow or air to yield a mixture, and wherein the mixer is arranged to route the mixture into the second segment of the tailpipe.   
   
   
       2 . The engine system of  claim 1 , wherein the mixer is disposed inline with the first segment and the second segment. 
   
   
       3 . The engine system of  claim 1 , wherein the mixer comprises:
 an upstream portion connected to the first segment;   a downstream portion connected to the second segment;   a neck-down portion that forms a nozzle opening, the neck-down portion disposed between the first segment and the second segment;   a plurality of tabs disposed around the neck-down portion and arranged to connect the first segment and the second segment;   wherein a gap is defined between the first segment, the second segment, and the plurality of tabs, and wherein the gap is arranged and constructed to pass the flow of air therethrough.   
   
   
       4 . The engine system of  claim 3 , wherein the first segment has a first inner diameter, wherein the nozzle opening has a second inner diameter, and wherein the second inner diameter is smaller than the first inner diameter. 
   
   
       5 . The engine system of  claim 3 , wherein the plurality of tabs is three tabs, and wherein the three tabs are arranged symmetrically around the nozzle opening. 
   
   
       6 . The engine system of  claim 3 , wherein a low pressure region is created on the downstream portion side of the nozzle opening during operation. 
   
   
       7 . The engine system of  claim 1 , wherein the mixer comprises:
 an upstream portion connected to the first segment;   a downstream portion connected to the second segment;   a neck-down portion connected to the upstream portion;   a neck-up portion connected to the downstream portion;   a mixing region disposed between the neck-down portion and the neck-up portion;   wherein the mixing region defines a nozzle opening, and wherein a plurality of openings fluidly connects the mixing region with an ambient supply of air.   
   
   
       8 . The engine system of  claim 7 , further comprising a shield disposed around the mixing region, wherein a cavity is defined between the mixing region and the shield, and wherein an air path is defined for the flow of air from the ambient supply of air, through a gap disposed between the shield and at least one of the first segment and the second segment, through the cavity, and through the plurality of openings. 
   
   
       9 . A method of reducing a temperature of an exhaust gas stream in a tailpipe of a vehicle, comprising the steps of:
 generating a flow of exhaust gas during operation of an engine;   treating the flow of exhaust gas with at least one after-treatment component;   routing the flow of exhaust gas to a tailpipe that includes a mixer;   admitting the flow of exhaust gas into the mixer;   mixing the flow of exhaust gas with a flow of air in the mixer to yield a mixture; and   expelling the mixture from the mixer.   
   
   
       10 . The method of  claim 9 , further comprising the step of filtering a particulate matter from the flow of exhaust gas in a particulate filter. 
   
   
       11 . The method of  claim 10 , further comprising the step of increasing a temperature of the flow of exhaust gas when the particulate filter is in a regeneration stage of operation. 
   
   
       12 . The method of  claim 11 , further comprising the step of cooling the flow of exhaust gas that is accomplished by the step of mixing the flow of exhaust gas with the flow of air. 
   
   
       13 . The method of  claim 9 , further comprising the step of passing the flow of air through a gap defined between a first segment of the tailpipe and a second segment of the tailpipe. 
   
   
       14 . The method of  claim 9 , wherein the mixer is a venturi mixer, and wherein the step of mixing further includes the steps of:
 accelerating the flow of exhaust gas;   creating a low pressure region adjacent to a nozzle opening; and   supplying the flow of air into the low pressure region.   
   
   
       15 . The method of  claim 9 , further comprising the step of admitting the flow of air through a plurality of openings. 
   
   
       16 . A method of diluting exhaust gas generated by an internal combustion engine installed in a vehicle, comprising the steps of:
 generating a flow of exhaust gas from the internal combustion engine;   admitting the flow of exhaust gas into a particulate filter;   increasing a temperature of the flow of exhaust gas passing through the particulate filter at times when the particulate filter is regenerating;   admitting the flow of exhaust gas at an elevated temperature into a mixer;   admitting a flow of air into the mixer;   mixing the flow of exhaust gas at the elevated temperature with the flow of air to yield a mixture;   expelling the mixture from the mixer.   
   
   
       17 . The method of  claim 16 , further comprising the step of passing the flow of air through a gap. 
   
   
       18 . The method of  claim 16 , wherein the mixer is a venturi mixer, and wherein the step of mixing further includes the steps of:
 accelerating the flow of exhaust gas;   creating a low pressure region adjacent to a nozzle opening; and   supplying the flow of air into the low pressure region.   
   
   
       19 . The method of  claim 16 , further comprising the step of admitting the flow of air into the mixer through a plurality of openings.