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.

What is claimed is: 
     
         1 . A fuel management system for a turbocharged spark ignition engine where the fuel management system controls fueling from a first fueling system that directly injects fuel into at least one cylinder as a liquid and increases knock suppression by evaporative cooling and where fueling is also provided by a second fueling system that injects fuel into a region outside of the cylinder;
 and where there is a first torque range wherein both fueling systems are used throughout this range;   and wherein the fraction of fuel in the cylinder that is introduced by the first fueling system increases with increasing manifold pressure;   and where fueling from the second fueling system alone is used when the torque is decreased below the lower end of the first torque range.   
     
     
         2 . The fuel management system of  claim 1  where the maximum knock suppression during a driving cycle is provided by operation with fueling from both fueling systems. 
     
     
         3 . The fuel management system of  claim 1  or  2  where the combustion stability is greater with operation of the first fueling system and the second fueling system than operation with the first fueling system alone. 
     
     
         4 . The fuel management system of  claim 1  where variable valve timing is used. 
     
     
         5 . The fuel management system of  claim 1  where the fraction of fuel provided by the first fueling system increases with manifold pressure so as to prevent knock. 
     
     
         6 . The fuel management system of  claim 1  where variable valve timing is used so as to reduce the fraction of fuel provided by the first fueling system. 
     
     
         7 . The fuel management system of  claim 1  where as the manifold pressure is increased, the increase in the fraction of fuel in the cylinder that is provided by the first fueling system is matched to that needed to prevent knock, during at least part of pressure range in which both the first and second fueling systems are used. 
     
     
         8 . The fuel management system of  claim 7  where the increase in the fraction of fuel provided by the first fueling system is matched to that needed to prevent knock throughout the entire first torque range. 
     
     
         9 . The fuel management system of  claim 1  where when the pressure in the manifold is increased, the fraction of fuel in the cylinder that is provided by the first fueling system is increased and is the minimum needed to prevent knock. 
     
     
         10 . The fuel management system of  claim 1  where only second fueling system is used between zero torque and the lowest torque in the first torque range. 
     
     
         11 . The fuel management system of  claim 1  where the lowest torque in the first torque range is the lowest torque at which the first fueling system is needed to prevent knock. 
     
     
         12 . The fuel management system of  claim 1  where the second fueling system uses port fuel injection. 
     
     
         13 . The fuel management system of  claim 1  where the first fueling system is operated so as to minimize wall wetting. 
     
     
         14 . The fuel management system of  claim 1  where during the first 30 seconds of operation all of the fuel is provided by the second fueling system. 
     
     
         15 . The fuel management system of  claim 1  where during engine start up all of the fuel is provided by the second fueling system. 
     
     
         16 . The fuel management system of  claim 1  where during engine startup a higher fraction of fuel is provided by the second fueling system than would ordinarily be used. 
     
     
         17 . A fuel management system for a turbocharged spark ignition engine where during part of the drive cycle the fuel management system controls fueling from a first fueling system that directly injects fuel into at least one cylinder as a liquid and increases knock suppression by evaporative cooling and from a second fueling system that injects fuel into a region outside of the cylinder;
 and where the fuel from the first fueling system is injected so as to provide a non uniform distribution of fuel in the cylinder;   and where there is a range of torque throughout which both fueling systems are used;   and where the fraction of fuel in the cylinder that is introduced by the first fueling system increases with increasing manifold pressure so as to prevent knock.   
     
     
         18 . The fuel management system of  claim 17  where second fuel system uses\ port fuel injection. 
     
     
         19 . A fuel management system for a turbocharged spark ignition engine where the fuel management system controls fueling from a first fueling system that directly injects fuel into at least one cylinder as a liquid and increases knock suppression by evaporative cooling and from a second fueling system that injects fuel into a region outside of the cylinder;
 and where there is a range of torque throughout which both fueling systems are used;   and where the fraction of fuel in the cylinder that is introduced by the first fueling system increases with increasing manifold pressure so as to prevent knock by providing increased knock resistance;   and where the fuel management system controls the change in the fraction of fuel introduced by the first fueling system using closed loop control that utilizes a sensor that detects knock;   and where the direct injection of fuel by the first fueling system is carried out so as to minimize wall wetting.   
     
     
         20 . The fuel management system of  claim 19  where the timing of the direct injection of fuel by the first fueling system is carried out so as to minimize wall wetting. 
     
     
         21 . The fuel management system of  claim 19  where the fuel is directly injected so that it encounters higher temperature gas when it is injected. 
     
     
         22 . The fuel management system of  claim 19  where the directly injected fuel is introduced in the cylinder after the inlet valve has closed. 
     
     
         23 . The fuel management system of  claim 19  where open loop control is also used. 
     
     
         24 . The fuel management system of  claim 23  where open loop control is used during transients in load. 
     
     
         25 . A fuel management system for a turbocharged spark ignition engine where the fuel management system controls fueling from a first fueling system that directly injects fuel into at least one cylinder as a liquid and increases knock suppression by evaporative cooling and where fueling is also provided by a second fueling system fueling system that uses port fuel injection
 and where there is a first torque range where fueling from the first fueling system is used throughout this range;   and where fueling from the second fueling system alone is used when the torque is decreased below the lower end of the first torque range.   
     
     
         26 . The fuel management system of  claim 25  where the second fueling system is also used throughout the first torque range. 
     
     
         27 . The fuel management system of  claim 25  where fueling from the second fueling system is used between zero torque and the lowest torque of the first torque range. 
     
     
         28 . The fuel management system of  claim 25  or  27  where the lowest torque in the first torque range is the lowest torque at which fueling from the first fueling is needed to prevent knock. 
     
     
         29 . The fuel management system of  claim 27  where when the highest knock resistance is required both the first and second fueling systems are used. 
     
     
         30 . The fuel management system of  claim 25  where for the first 30 seconds of engine operation more fueling is provided by the second fueling system that would ordinarily be the case. 
     
     
         31 . The fuel management system of  claim 25  where all of the fueling is provided by the second fueling system during the first 30 seconds of operation.