Fuel management system for variable anti-knock agent octane enhancement of gasoline engines

A turbocharged, spark ignition engine which uses port fuel injection of gasoline from a first source in addition to direct fuel injection of liquid denatured ethanol from a second source comprising:

• a spark ignition engine;
• a turbocharger;
• means for port fuel injection of gasoline from the first source;
• means for direct fuel injection of liquid denatured ethanol from the second source;
• wherein during part of the engine operating time, the engine is powered both by gasoline that is port fuel injected and ethanol that is directly injected;
• and
• wherein during part of the operating time the instantaneous ethanol energy fraction is at least 20%;
• and
• wherein the ethanol is directly injected in such an amount that the evaporative cooling of the fuel/air charge by the directly injected ethanol combined with the higher octane number of the ethanol enhances the octane number by at least 20 octane numbers;
• and
• a fuel management system including a microprocessor which increases the ethanol energy fraction with increasing torque so that it is sufficient to prevent knock;
• and
• wherein the turbocharged direct injection spark ignition engine is operated at a substantially stoichiometric air/fuel ratio.

A turbocharged, spark ignition engine which uses portfuel injection of gasoline from a first source in addition to direct fuel injection of liquid denatured ethanol from a second source comprising:

• a spark ignition engine;
• a turbocharger;
• means for port fuel injection of gasoline from the first source;
• means for direct injection of liquid denatured ethanol from the second source;
• wherein during part of the engine operating time, the engine is powered both by gasoline that is port fuel injected and by ethanol that is directly injected;
• and
• wherein during part of the operating time the instantaneous ethanol energy fraction is at least 20%;
• and
• wherein the ethanol is directly injected in an amount such that the evaporative cooling of the fuel/air charge by the directly injected ethanol combined with the higher octane number of the ethanol enhances the octane number by at least 20 octane numbers;
• and
• a fuel management system including a microprocessor which increases the ethanol energy fraction with increasing torque so that it is sufficient to prevent knock;
• and
• wherein the fuel management system minimizes ethanol use by using information from a knock detector;
• and
• wherein the turbocharged direct injection spark ignition engine is operated at a substantially stoichiometric air/fuel ratio.

A turbocharged spark ignition engine which uses port fuel injection of gasoline from a first source in addition to direct injection of liquid denatured ethanol from a second source comprising:

• a spark ignition engine;
• a turbocharger;
• means for port fuel injection of gasoline from the first source;
• means for direct injection of liquid denatured ethanol from the second source;
• wherein during part of the engine operating time, the engine is powered by a fuel that consists of both gasoline that is port fuel injected and ethanol that is directly injected;
• and
• wherein under some operating conditions the instantaneous ethanol energy fraction is at least 20%;
• and
• wherein the ethanol is directly injected in an amount such that the evaporative cooling of the fuel/air charge by the directly injected ethanol combined with the higher octane number of the ethanol enhances the octane number by at least 20 octane numbers;
• and
• a fuel management system including a microprocessor which increases the ethanol energy fraction with increasing torque so that it is sufficient to prevent knock;
• and
• wherein the fuel management system minimizes the ethanol use by using information from a knock sensor;
• and
• wherein the turbocharged direct injection spark ignition engine is operated at a substantially stoichiometric air /fuel ratio;
• wherein the fuel management microprocessor uses information about the level of ethanol in the second source to control the turbocharger;
• and further wherein the turbocharging is eliminated or reduced when there is no ethanol in the second source.