Gasoline Particulate Reduction Using Optimized Port And Direct Injection

Abstract

Additional approaches for the reduction of particulate emissions in gasoline engines using optimized port+direct injection are described. These embodiments include control of the amount of directly injected fuel so as to avoid a threshold increase in particulates due to piston wetting and reduction of cold start emissions by use of air preheating using variable valve timing.

What is claimed is: 
     
         1 . A spark ignition engine where temporary advanced closing of the exhaust valve is used to provide hot gas which goes into the manifold;
 and where a control system determines when the exhaust valve timing returns from the advanced closing to a less advanced closing.   
     
     
         2 . The spark ignition engine of  claim 1  where the temporary advanced closing reduces particulate generation relative to what it would have been if the temporary advanced exhaust valve timing were not used. 
     
     
         3 . The spark ignition engine of  claim 1  where the temporary advanced closing reduces hydrocarbon emission relative to what it would have been if the temporary advanced exhaust valve timing were not used. 
     
     
         4 . The spark ignition engine of  claim 1  where the exhaust valve timing is temporarily advanced by between 30 and 60 crank angle degrees. 
     
     
         5 . The spark ignition engine of  claim 1  where the control system uses closed loop control where information is provided by a sensor to determine when to stop the use of the advanced exhaust valve timing. 
     
     
         6 . The spark ignition engine of  claim 1  where the control system uses open loop control to determine when to stop using the advanced exhaust valve timing. 
     
     
         7 . The spark ignition engine of  claim 1  where the advanced exhaust valve closing is controlled using information about the engine temperature. 
     
     
         8 . The spark ignition engine of  claim 1  where port fuel injection is employed. 
     
     
         9 . The spark ignition engine of  claim 1  where direct fuel injection employed. 
     
     
         10 . The spark ignition engine of  claim 1  where the temporary advanced valve closing is used during cold start and where the hot gas assists in evaporation of liquid fuel from the manifold. 
     
     
         11 . A spark ignition engine where temporary advanced closing of the exhaust valve is used during cold start to provide hot gas which goes into the manifold;
 and where electricity is used to crank the engine while the temporary closing of the exhaust valve is employed.   
     
     
         12 . The spark ignition engine of  claim 11  where temporary advanced closing of the exhaust valve is used for one engine cycle. 
     
     
         13 . The spark ignition engine of  claim 11  where the temporary advanced closing of the exhaust valve is used for more than one engine cycle. 
     
     
         14 . The spark ignition engine of  claim 11  where the power of the electricity that is used to crank the engine is between 100 and 1000 watts. 
     
     
         15 . The spark ignition engine of  claim 11  where an electrically powered oil pump is used. 
     
     
         16 . The spark ignition engine of  claim 11  where a bistable cam is used. 
     
     
         17 . The spark ignition engine of  claim 11  where all electric valve timing or electric assist valve timing is employed. 
     
     
         18 . The spark ignition engine of  claim 11  where a spark is not used when the temporary advanced exhaust valve timing is employed.