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

• US 20060102146A1
• Filed: 09/19/2005
• Published: 05/18/2006
• Est. Priority Date: 11/18/2004
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Bromberg, Leslie, Cohn, Daniel R., Heywood, John B.
• Granted Patent: US 7,444,987 B2
• Time in Patent Office: Days
• US Class Current: 123/406.290
• 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. Fuel management system for operation of a spark ignition gasoline engine comprising:

a gasoline engine;

a source of an anti-knock agent;

an injector for direct injection of the anti-knock agent into a cylinder of the engine; and

a fuel management control system for controlling injection of the anti-knock agent into the cylinder to control knock;

wherein the anti-knock agent is selected from the group consisting of methanol, tertiary butyl alcohol, MTBE, ETBE, and TAME.

2. The system of claim 1 wherein the anti-knock agent is mixed with water.

3. The system of claim 1 wherein the anti-knock agent is mixed with a lubricant.

4. The system of claim 1 wherein the anti-knock agent is injected proximate to a cylinder wall and swirl creates a ring of the anti-knock agent.

5. The system of claim 1 wherein the engine is operated with substantially a stoichiometric air/fuel ratio.

6. The system of claim 1 wherein the anti-knock agent is added only during portions of the drive cycle requiring knock resistance and its use is minimized during those times.

7. The system of claim 1 wherein the torque of the engine at which knock occurs can be increased by at least a factor of two by the direct injection of the anti-knock agent.

8. The system of claim 1 wherein horsepower of a given size engine can be at least doubled by using anti-knock agent octane enhancement.

9. Fuel management system for operation of a spark engine gasoline engine comprising:

a gasoline engine;

a source of an anti-knock agent;

an injector for direct injection of the anti-knock agent into a cylinder of the engine; and

a fuel management control system for controlling injection of the anti-knock agent into the cylinder when engine torque is above a selected fraction of maximum torque.

10. The system of claim 9 wherein the anti-knock agent is selected from the group consisting of methanol, tertiary butyl alcohol, MTBE, ETBE, and TAME.

11. The system of claim 9 wherein the torque levels at which the anti-knock agent is directly injected are those where knock would occur absent the anti-knock agent injection.

12. The system of claim 9 wherein the fraction of total fuel provided by the directly injected anti-knock agent increases with increasing torque.

13. The system of claim 9 wherein gasoline is port fuel injected.

14. The system of claim 9 wherein octane number is enhanced with increasing torque.

15. The system of claim 9 wherein an octane enhancement of more than 20 octane number is achieved.

16. The system of claim 9 wherein the fuel management system includes a microprocessor that operates in an open loop fashion on a predetermined correlation between a required octane number enhancement and fraction of fuel provided by the anti-knock agent.

17. The system of claim 9 wherein the gasoline engine includes a knock senor providing a feedback signal to a fuel management microprocessor to minimize the amount of the anti-knock agent added to prevent knock in a closed loop fashion.

18. The system of claim 9 wherein the injector provides non-uniform deposition of the anti-knock agent within a cylinder.

19. The system of claim 18 wherein the anti-knock agent is deposited near the walls of the cylinder.

20. The system of claim 18 wherein the non-uniform deposition is obtained through direct injection and charge swirl.

21. The system of claim 9 wherein the anti-knock agent is mixed with water.

22. The system of claim 9 wherein the anti-knock agent is mixed with a lubricant.

23. The system of claim 9 wherein the engine has substantial organized motion such as swirl.

24. The system of claim 9 wherein the system includes a measure of the amount of the anti-knock agent available to control turbocharging, supercharging, or spark retard when the amount of anti-knock agent is low.

25. The system of claim 9 wherein the gasoline is directly injected into the cylinder.

26. The system of claim 9 wherein the fuel management system substantially minimizes the amount of anti-knock agent used over a drive cycle.

27. The system of claim 9 wherein turbocharging or supercharging are reduced or eliminated and/or spark retard is increased when anti-knock agent is not available.

28. The system of claim 9 wherein the engine is operated with substantially a stoichiometric fuel/air ratio.

29. The system of claim 9 wherein the engine can be operated with only gasoline and knock can be avoided by reducing the maximum torque and horsepower relative to values when the anti-knock agent is directly injected into the cylinder.

30. The system of claim 29 wherein the horsepower is reduced by at least a factor of two.

31. The system of claim 9 wherein the fuel management control system uses anti-knock agent level in the ethanol tank as an input to control a turbocharger, supercharger or spark retard.

32. The system of claim 31 wherein the turbocharger, supercharger, or spark retard is adjusted to prevent knock.