Optimized fuel management system for direct injection ethanol enhancement of gasoline engines

Abstract

Fuel management system for enhanced operation of a spark ignition gasoline engine. Injectors inject an anti-knock agent such as ethanol directly into a cylinder. It is preferred that the direct injection occur after the inlet valve is closed. It is also preferred that stoichiometric operation with a three way catalyst be used to minimize emissions. In addition, it is also preferred that the anti-knock agents have a heat of vaporization per unit of combustion energy that is at least three times that of gasoline.

1 - 25 . (canceled) 
     
     
         26 . A spark ignition engine where fuel is directly injected into at least one engine cylinder and where fuel is also introduced into the engine by port injection and where the ratio of directly injected fuel to the port injected fuel is increased with increasing torque so as to prevent knock. 
     
     
         27 . The spark ignition engine of  claim 26  where only direct injection of fuel is used when the highest amount of torque is needed. 
     
     
         28 . The spark ignition engine of  claim 26  where when the highest amount of torque is needed, the amount of fuel that is port fueled is smaller than the amount that is directly injected. 
     
     
         29 . The spark ignition engine of  claim 26  where the port injected fuel is used to provide combustion stability. 
     
     
         30 . The spark ignition engine of  claim 26  where the engine is operated with a substantially stoichiometric fuel/air ratio. 
     
     
         31 . The spark ignition engine of  claim 26  where gasoline is simultaneously introduced into the engine by direct injection and by port fuel injection. 
     
     
         32 . The spark ignition engine of  claim 26  where ethanol is simultaneously introduced into the engine by direct injection and by port fuel injection. 
     
     
         33 . The spark ignition engine of  claim 26  where fuel is directly injected so as to have a greater concentration in the end gas region. 
     
     
         34 . The spark ignition engine of  claim 33  where fuel is directly injected so as to have a greater concentration in near the walls of the cylinder. 
     
     
         35 . The spark ignition engine of  claim 26  where fuel is directly injected after the inlet valve has closed. 
     
     
         36 . The spark ignition engine of  claim 26  where at low torque the engine is fueled only by port fuel injection. 
     
     
         37 . The spark ignition engine of  claim 26  where the compression ratio is 11 or greater. 
     
     
         38 . The spark ignition engine of  claim 26  where the manifold pressure is 2 bar or greater. 
     
     
         39 . The spark ignition engine of  claim 26  further including cooled EGR. 
     
     
         40 . A spark ignition engine which is fueled with an alcohol-gasoline mixture that is directly injected into a least one engine cylinder after the inlet valve has closed and where the alcohol-gasoline mixture is directly injected so as to be non-uniformly distributed in the cylinder with a greater concentration in the outer region of the cylinder. 
     
     
         41 . The spark ignition engine of  claim 40  further including the introduction of fuel by port fuel injection. 
     
     
         42 . The spark ignition engine of  claim 41  where at low torque the engine is fueled only by port fuel injection. 
     
     
         43 . The spark ignition engine of  claim 41  where the ratio of fuel that is directly injected to fuel that is port fuel injected increases with increasing torque. 
     
     
         44 . The spark ignition engine of  claim 40  further including swirl. 
     
     
         45 . The spark ignition engine of  claim 40  where the compression ratio is 11 or greater. 
     
     
         46 . The spark ignition engine of  claim 40  where the compression ratio is 2 bar or greater.