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A compression ignition engine uses two or more fuel charges having two or more reactivities to control the timing and duration of combustion. In a preferred implementation, a lower-reactivity fuel charge is injected or otherwise introduced into the combustion chamber, preferably sufficiently early t

A compression ignition engine uses two or more fuel charges having two or more reactivities to control the timing and duration of combustion. In a preferred implementation, a lower-reactivity fuel charge is injected or otherwise introduced into the combustion chamber, preferably sufficiently early that it becomes at least substantially homogeneously dispersed within the chamber before a subsequent injection is made. One or more subsequent injections of higher-reactivity fuel charges are then made, and these preferably distribute the higher-reactivity matter within the lower-reactivity chamber space such that combustion begins in the higher-reactivity regions, and with the lower-reactivity regions following thereafter. By appropriately choosing the reactivities of the charges, their relative amounts, and their timing, combustion can be tailored to achieve optimal power output (and thus fuel efficiency), at controlled temperatures (and thus controlled NOx), and with controlled equivalence ratios (and thus controlled soot).

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1. A compression ignition combustion method for an internal combustion engine, the method including the steps of: a. supplying an initial fuel charge into a combustion chamber of the internal combustion engine,b. subsequently supplying a subsequent fuel charge into the combustion chamber, the subseq

1. A compression ignition combustion method for an internal combustion engine, the method including the steps of: a. supplying an initial fuel charge into a combustion chamber of the internal combustion engine,b. subsequently supplying a subsequent fuel charge into the combustion chamber, the subsequent fuel charge having different reactivity than the initial fuel charge,c. compressing the fuel charges within the combustion chamber to induce ignition of the fuel charges,wherein the fuel charges define a stratified distribution of fuel reactivity within the combustion chamber at the time of ignition, with regions of highest fuel reactivity being spaced from regions of lowest fuel reactivity. 2. The method of claim 1wherein the regions are distributed within the combustion chamber such that the start and duration of fuel combustion provide:(1) NOx emissions of less than 1.0 g/kW-hr, and(2) soot emissions of less than 0.1 g/kW-hr. 3. The method of claim 1wherein the regions are distributed within the combustion chamber such that the start and duration of fuel combustion provide one or more of:(1) engine net indicated thermal efficiency of greater than 48%, and(2) engine gross indicated thermal efficiency of greater than 51%. 4. The method of claim 1wherein the regions are distributed within the combustion chamber to provide:(1) NOx emissions of less than 1.0 g/kW-hr,(2) soot emissions of less than 0.1 g/kW-hr, and(3) engine gross indicated thermal efficiency of greater than 51%. 5. The method of claim 1 wherein: a. one of the initial fuel charge and the subsequent fuel charge contains gasoline; andb. the other of the initial fuel charge and the subsequent fuel charge contains diesel fuel,prior to being supplied to the combustion chamber. 6. The method of claim 1 wherein: a. one of the initial fuel charge and the subsequent fuel charge contains a first fuel; andb. the other of the initial fuel charge and the subsequent fuel charge contains a mixture of the first fuel and an additive,prior to being supplied to the combustion chamber. 7. The method of claim 1 wherein: a. one of the initial fuel charge and the subsequent fuel charge is supplied from a first tank; andb. the other of the initial fuel charge and the subsequent fuel charge is supplied from both the first tank and from a second tank. 8. The method of claim 1 wherein the fuel charges are supplied to combust to attain peak cylinder pressure at or after Top Dead Center (TDC). 9. The method of claim 1 wherein the fuel charges are supplied to combust to attain peak cylinder pressure between Top Dead Center (TDC) and 20 degrees after TDC. 10. The method of claim 1 wherein the fuel charges are supplied to combust to attain peak cylinder pressure between approximately 5 and 15 degrees after Top Dead Center (TDC). 11. The method of claim 1 wherein the fuel charges are supplied to combust to attain CA50 between approximately 0 to 10 degrees after Top Dead Center (TDC). 12. The method of claim 1 wherein the initial fuel charge is supplied into the combustion chamber sufficiently prior to Top Dead Center (TDC) that the initial fuel charge is at least substantially homogeneously dispersed within the combustion chamber when a compression stroke is halfway completed. 13. The method of claim 1 wherein the subsequent fuel charge is supplied into the combustion chamber during a compression stroke. 14. The method of claim 1 wherein the subsequent fuel charge is supplied into the combustion chamber between 180 and 10 degrees prior to Top Dead Center (TDC). 15. The method of claim 1 wherein the subsequent fuel charge is supplied into the combustion chamber at 40 or more degrees prior to Top Dead Center (TDC). 16. The method of claim 1 wherein: a. the initial fuel charge is supplied into the combustion chamber through an intake port;b. the subsequent fuel charge is supplied into the combustion chamber via direct injection. 17. The method of claim 1 wherein the initial fuel charge is supplied into the combustion chamber sufficiently prior to Top Dead Center (TDC) that the initial fuel charge is at least substantially homogeneously dispersed within the combustion chamber when the subsequent fuel charge is supplied to the combustion chamber. 18. The method of claim 1 wherein: a. two or more subsequent fuel charges are supplied into the combustion chamber, andb. the subsequent fuel charges are introduced into the combustion chamber at different times. 19. The method of claim 18 wherein the subsequent fuel charges include: a. a first subsequent fuel charge injected into the combustion chamber between: (1) the closing of an intake port opening onto the combustion chamber, and(2) approximately 40 degrees prior to top dead center; andb. a second subsequent fuel charge injected into the combustion chamber after the first subsequent fuel charge. 20. The method of claim 18 wherein the subsequent fuel charges include: a. a first subsequent fuel charge, wherein at least a major portion of the first subsequent fuel charge is injected toward an outer region located at or near an outer radius of a piston face which partially bounds the combustion chamber;b. a second subsequent fuel charge supplied into the combustion chamber after the first subsequent fuel charge, wherein at least a major portion of the second subsequent fuel charge is injected toward an inner region spaced inwardly from the outer radius of the piston face. 21. The method of claim 18 wherein the subsequent fuel charges include: a. a first subsequent fuel charge, wherein at least a major portion of the first subsequent fuel charge is injected toward a region located outside of an outer third of the radius of a piston face which partially bounds the combustion chamber;b. a second subsequent fuel charge supplied into the combustion chamber after the first subsequent fuel charge, wherein at least a major portion of the second subsequent fuel charge is injected toward a region located inside an outer fourth of the radius of the piston face. 22. A compression ignition combustion method for an internal combustion engine, the method including the steps of: a. supplying an initial fuel charge into a combustion chamber of an internal combustion engine;b. thereafter injecting a second fuel charge into the combustion chamber, wherein at least a substantial portion of the second fuel charge is injected toward a region located outside of an outer third of the radius of a piston face which partially bounds the combustion chamber;c. thereafter injecting a third fuel charge into the combustion chamber, wherein at least a substantial portion of the third fuel charge is injected toward a region located inside of an outer fourth of the radius of the piston face. 23. The compression ignition combustion method of claim 22 wherein the initial fuel charge has a lower reactivity than one or more of the second and third fuel charges. 24. The method of claim 22 wherein: a. the fuel charges are compressed within the combustion chamber until they ignite, andb. the fuel charges provide a stratified distribution of fuel reactivity within the combustion chamber at the time of ignition, with regions of highest fuel reactivity being spaced from regions of lowest fuel reactivity. 25. A compression ignition combustion method for an internal combustion engine, the method including the steps of: a. supplying an initial fuel charge into a combustion chamber of the internal combustion engine, the initial fuel charge containing a first fuel type;b. subsequently supplying a subsequent fuel charge into the combustion chamber, the subsequent fuel charge containing: (1) the first fuel type, and(2) an additive which alters the reactivity of first fuel type,c. compressing the fuel charges within the combustion chamber to initiate ignition of the fuel charges,wherein the combustion chamber has a stratified distribution of fuel reactivity at the time of ignition, with regions of highest fuel reactivity being spaced from regions of lowest fuel reactivity.