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 - 5 . (canceled) 
     
     
         6 . A spark ignition engine where two fuels are introduced into the engine where the first fuel has a greater alcohol concentration than the second fuel; and where the first fuel is produced by onboard separation of fuel from a third fuel which is a gasoline-alcohol mixture; and where the ratio of the first fuel that is used in the engine to the second fuel that is used in the engine increases with increasing torque. 
     
     
         7 . The spark ignition engine of  claim 6  where a membrane is employed in the onboard separation. 
     
     
         8 . The engine system of  claim 7  where the membrane is an inorganic membrane. 
     
     
         9 . The engine system of  claim 7  where the membrane is an organic membrane. 
     
     
         10 . The engine system of  claim 7  where the membrane is a transfusion membrane. 
     
     
         11 . The engine system of  claim 7  where the membrane is a porous membrane. 
     
     
         12 . The engine system of  claims 6  or  7  where the alcohol in the gasoline-alcohol mixture is ethanol. 
     
     
         13 . The engine system of  claims 6  or  7  where the first fuel is stored in a tank to which additional alcohol can be added. 
     
     
         14 . The engine system of  claims 6  or  7  where ratio of the first fuel to the second fuel is varied so as to prevent knock at the torque is increased. 
     
     
         15 . The spark ignition engine of  claims 6  or  7  where the engine is operated with a substantially stoichiometric fuel to air ratio. 
     
     
         16 . The spark ignition engine of  claims 6  or  7  where a closed loop control system with a knock detector is used to determine the ratio of amount of the first fuel to second fuel used in the engine. 
     
     
         17 . The spark ignition engine of  claims 6  or  7  where an open loop control system with a look up table is used to determine the ratio of the first fuel to the second fuel. 
     
     
         18 . The spark ignition engine of  claims 6  or  7  where a control system is used to minimize the amount of second fuel that is used to prevent knock. 
     
     
         19 . The spark ignition engine of  claims 6  or  7  where the first fuel is injected so as to increase its vaporization cooling of the fuel-air mixture in at least one engine cylinder. 
     
     
         20 . The spark ignition engine of  claim 19  where the first fuel is directly injected into the engine. 
     
     
         21 . The spark ignition engine of  claims 6  or  7  where the second fuel contains gasoline. 
     
     
         22 . The spark ignition engine of  claim 7  where the second fuel is produced by onboard separation from the third fuel. 
     
     
         23 . A spark ignition engine where two fuels are introduced into the engine where the first foci has a greater knock resistance than the second fuel and where the first fuel is introduced into the engine so as to produce a non-uniform distribution of the first fuel with a greater concentration in the end gas region; and where the first and second fuel are produced by on board separation of a third fuel. 
     
     
         24 . The spark ignition engine of  claim 23  where a membrane is employed in the onboard separation. 
     
     
         25 . The engine system of  claim 23  where the third fuel is a gasoline-alcohol mixture and the first fuel has a greater alcohol concentration than the second fuel. 
     
     
         26 . The engine system of  claim 23  where ratio of the amount of first fuel used in the engine to the amount of the second fuel used in the engine is increased so as to prevent knock as the torque is increased. 
     
     
         27 . The spark ignition engine of  claim 23  where a closed loop control system with a knock detector is used to determine the ratio of amount of the first fuel to second fuel used in the engine. 
     
     
         28 . The spark ignition engine of  claim 23  where the first fuel is injected so as to increase its vaporization cooling of the fuel-air mixture in at least one engine cylinder. 
     
     
         29 . The spark ignition engine of  claim 23  where the first fuel is directly injected into the engine. 
     
     
         30 . The spark ignition engine of  claim 23  where the first fuel is introduced into the engine so as to have a greater concentration in the periphery of the engine cylinders.