Fuel management system for variable ethanol octane enhancement of gasoline engines

• US 7,314,033 B2
• Filed: 11/18/2004
• Issued: 01/01/2008
• Est. Priority Date: 11/18/2004
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Bromberg, Leslie, Cohn, Daniel R., Heywood, John B.
• Primary Examiner(s): Cronin; Stephen K.
• Assistant Examiner(s): Ali; Hyder
• Application Number:
  US10/991,774
• Publication Number:
  US 20060102145A1
• Time in Patent Office: 1,139 Days
• Field of Search: 123/1.A, 123/198.A, 123/525, 123/25.A, 123/25.J, 123/435, 123/575, 123/406.29, 123/406.47
• US Class Current: 123/198.00A
• CPC Class Codes: F02B 17/00 Engines characterised by means for effecting stratification of charge in cylinders
• CPC Class Codes: F02B 17/005 having direct injection in the combustion chamber
• CPC Class Codes: F02B 47/00 Methods of operating engines involving adding non-fuel substances or anti-knock agents to combustion air, fuel, or fuel-air mixtures of engines
• CPC Class Codes: F02B 47/04 the substances being other than water or steam only
• CPC Class Codes: F02B 51/00 Other methods of operating engines involving pretreating of, or adding substances to, combustion air, fuel, or fuel-air mixture of the engines
• CPC Class Codes: F02B 7/00 Engines characterised by the fuel-air charge being ignited by compression ignition of an additional fuel characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition F02B11/00
• CPC Class Codes: F02D 19/08 simultaneously using pluralities of fuels F02D19/12 takes precedence
• CPC Class Codes: F02D 19/081 Adjusting the fuel composition or mixing ratio; Transitioning from one fuel to the other
• CPC Class Codes: F02D 2041/389 for injecting directly into the cylinder
• CPC Class Codes: F02D 2200/1002 Output torque
• CPC Class Codes: F02D 35/027 using knock sensors
• CPC Class Codes: F02D 41/0025 Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
• CPC Class Codes: F02D 41/3094 the fuel injection being effected by at least two different injectors, e.g. one in the intake manifold and one in the cylinder
• CPC Class Codes: F02M 25/00 Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding secondary air to fuel-air mixture F02M23/00; adding exhaust gases F02M26/00; fuel-injection apparatus operating simultaneously on two or more fuels or on a liquid fuel and another liquid F02M43/00
• CPC Class Codes: F02M 25/14 adding anti-knock agents, not provided for in subgroups F02M25/022 - F02M25/10
• CPC Class Codes: F02P 5/045 combined with electronic control of other engine functions, e.g. fuel injection in general F02D37/02
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

Fuel management system for efficient operation of a spark ignition gasoline engine. Injectors inject an anti-knock agent such as ethanol directly into a cylinder of the engine. A fuel management microprocessor system controls injection of the anti-knock agent so as to control knock and minimize that amount of the anti-knock agent that is used in a drive cycle. It is preferred that the anti-knock agent is ethanol. The use of ethanol can be further minimized by injection in a non-uniform manner within a cylinder. The ethanol injection suppresses knock so that higher compression ratio and/or engine downsizing from increased turbocharging or supercharging can be used to increase the efficiency of the engine.

Claims

1. 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 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 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 uses closed loop control with information from a knock detector to vary the ethanol energy fraction when the instantaneous ethanol fraction is at least 20%; and

wherein the fuel management system minimizes the ethanol use by using information from the knock detector; and

wherein the turbocharged direct injection spark ignition engine is operated at a substantially stochiometric air/fuel ratio; and

wherein the fuel management microprocessor uses information about the ethanol level in the second source to control the turbocharger; and

wherein the turbocharging is eliminated or reduced when there is no ethanol in the second source; and

wherein a vehicle with this spark ignition engine can be operated on port fuel injected gasoline alone without knock.

2. 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 fuel management system uses the combination of open loop control using a look up table and closed loop control using a knock detector to vary the ethanol energy fraction; and

wherein the fuel management system minimizes the ethanol use by using information from the knock detector; and

wherein the turbocharged direct injection spark ignition engine is operated at a substantially stoichiometric air/fuel ratio; and

wherein the fuel management microprocessor uses information about the level of ethanol in the second source to control the turbocharger; and

and further wherein the turbocharging is eliminated or reduced when there is no ethanol in the second source; and

wherein a vehicle using this engine can be operated on port fueled gasoline alone without knock; and

further wherein liquid ethanol is directly injected in an amount such that the turbocharged spark ignition engine is operated without knock at a horsepower level which is at least twice the horsepower level without knock as is the case when it is when operated with port fuel injected gasoline alone.

3. 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 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 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 uses the combination of open loop control using a look up table and closed loop control using a knock detector to vary the ethanol energy fraction; and

wherein the fuel management system minimizes ethanol use by using information from the knock detector; and

wherein the turbocharged direct injection spark ignition engine is operated at a substantially stoichiometric air/fuel ratio; and

wherein the fuel management system 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; and

wherein a vehicle using this engine can be operated on port fueled gasoline alone without knock; and

wherein the fuel management microprocessor uses information about the level of the ethanol in the second source to control spark retard; and

where the spark retard is increased when there is no ethanol in the second source; and

further wherein liquid ethanol is directly injected in an amount such that the turbocharged spark ignition engine is operated without knock at a horsepower level which is at least twice the horsepower level without knock than is the case when it is when operated with port fuel injected gasoline alone.

4. 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 uses a combination of open loop control with a look up table and closed loop control using a knock sensor to control the ethanol energy fraction; and

wherein the open loop control uses a predetermined correlation between a required octane enhancement and the fraction of the fuel provided by ethanol;

wherein the fuel management system minimizes the ethanol use by using information from the 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; and

wherein a vehicle using this spark ignition engine can be operated on port fueled gasoline alone without knock; and

wherein the fuel management microprocessor uses information about the level of the ethanol in the second source to control spark retard; and

wherein the spark retard is increased when there is no ethanol in the second source; and

wherein the fuel management system includes a measure of the ethanol in the second source to control turbocharging when the amount of ethanol is low; and

wherein the fuel management system includes a measure of the ethanol in the second source to control spark retard when the amount of ethanol is low;

further wherein liquid ethanol is directly injected in an amount such that the turbocharged spark ignition engine operates without knock at a horsepower level which is at least twice the horsepower level without knock which is the case when operated with port fuel injected gasoline alone; and

wherein the engine can be operated on the denatured ethanol alone; and

wherein the ethanol fraction needed to prevent knock is reduced by concentrating the ethanol in regions that make up the end-gas and are prone to auto-ignition;

wherein the ethanol is injected so as to place the ethanol near the walls of the engine cylinder; and

wherein swirl is used to create a ring of ethanol near the walls of the cylinder; and

wherein the ethanol is mixed with a lubricant.