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A gaseous-fuelled internal combustion engine and a method of engine operation improve combustion stability and reducing emissions of NOx, PM, and unburned hydrocarbons. The method comprises fuelling an internal combustion engine with hydrogen and natural gas, which can be directly injected into the

A gaseous-fuelled internal combustion engine and a method of engine operation improve combustion stability and reducing emissions of NOx, PM, and unburned hydrocarbons. The method comprises fuelling an internal combustion engine with hydrogen and natural gas, which can be directly injected into the combustion chamber together or introduced separately. Of the total gaseous fuel delivered to the engine, at least 5% by volume at standard temperature and pressure is hydrogen. For at least one engine operating condition, the ratio of fuel rail pressure to peak in-cylinder pressure is at least 1.5:1. A fuel injection valve introduces the gaseous fuel mixture directly into the combustion chamber. Two separate fuel injection valves could also introduce the methane and hydrogen separately. An electronic controller controls timing for operating the fuel injection valve(s). The engine has a preferred compression ratio of at least 14:1.

대표청구항 ▼

1. A method of operating a direct injection diesel cycle internal combustion engine, comprising introducing a gaseous fuel mixture directly into a combustion chamber of said engine, wherein said gaseous fuel mixture comprises methane and between 5% and 60% hydrogen by volume at standard temperature

1. A method of operating a direct injection diesel cycle internal combustion engine, comprising introducing a gaseous fuel mixture directly into a combustion chamber of said engine, wherein said gaseous fuel mixture comprises methane and between 5% and 60% hydrogen by volume at standard temperature and pressure, and for at least one engine operating condition, maintaining a fuel rail to peak in-cylinder pressure ratio of at least 1.5:1 when introducing the gaseous fuel mixture into said combustion chamber, and adjusting start of fuel injection timing for said gaseous fuel mixture compared to start of fuel injection timing for methane to compensate for an earlier combustion event of said gaseous fuel mixture due to reduced ignition delay. 2. The method of claim 1 wherein said gaseous fuel mixture is selected from the group consisting of a gaseous fuel mixture comprising between 10% and 50% hydrogen by volume at standard temperature and pressure, a gaseous fuel mixture comprising between 15% and 40% hydrogen by volume at standard temperature and pressure, and a gaseous fuel mixture comprising between 20% and 35% hydrogen by volume at standard temperature and pressure. 3. The method of claim 1 further comprising controlling fuel injection timing so that the mid-point of integrated combustion heat release occurs between 2 and 30 crank angle degrees after top dead center. 4. The method of claim 1 further comprising controlling fuel injection timing so that in at least one engine operating condition the mid-point of integrated combustion heat release occurs between 5 and 15 crank angle degrees after top dead center. 5. The method of claim 1 further comprising injecting a pilot fuel directly into said combustion chamber about 1 millisecond before start of injection of said gaseous fuel mixture. 6. The method of claim 5 wherein over an engine operating map said pilot fuel is on average between 3% and 10% of the fuel that is consumed by said engine on an energy basis. 7. The method of claim 1 further comprising maintaining a fuel rail to peak in-cylinder pressure ratio of at least 1.5:1 when introducing said gaseous fuel mixture into said combustion chamber for all engine operating conditions. 8. The method of claim 1 wherein said gaseous fuel mixture comprises between 10% and 50% hydrogen by volume at standard temperature and pressure. 9. The method of claim 1 comprising storing said hydrogen separately from said methane and mixing said hydrogen and methane to form said gaseous fuel mixture. 10. The method of claim 1 wherein said methane is stored as a methane and hydrogen blend and said hydrogen is stored separately from said methane and hydrogen blend, the method further comprising mixing said hydrogen and said methane and hydrogen blend to form said gaseous fuel mixture. 11. The method of claim 1 further comprising controlling the proportions of hydrogen and methane in said gaseous fuel mixture as a function of engine operating conditions. 12. The method of claim 1, wherein the gaseous fuel mixture comprises natural gas, the method further comprises adjusting start of fuel injection timing for said gaseous fuel mixture compared to start of fuel injection timing for natural gas to compensate for an earlier combustion event of said gaseous fuel mixture due to reduced ignition delay. 13. A method of operating a direct injection Diesel cycle internal combustion engine, comprising introducing a gaseous fuel mixture directly into a combustion chamber of said engine, wherein said gaseous fuel mixture comprises methane and between 5% and 60% hydrogen by volume at standard temperature and pressure, and for at least one engine operating condition, maintaining a fuel rail to peak in-cylinder pressure ratio of at least 1.5:1 when introducing the gaseous fuel mixture into said combustion chamber, and changing respective proportions of hydrogen and methane in said gaseous fuel mixture to predetermined amounts responsive to detected engine operating conditions, and for each respective gaseous fuel mixture adjusting start of fuel injection timing compared to start of fuel injection timing for methane to compensate for an earlier combustion event of said gaseous fuel mixture due to reduced ignition delay. 14. The method of claim 13, wherein the gaseous fuel mixture comprises natural gas, the method further comprising changing respective proportions of hydrogen and natural gas in said gaseous fuel mixture to predetermined amounts responsive to detected engine operating conditions, and for each respective gaseous fuel mixture adjusting start of fuel injection timing compared to start of fuel injection timing for natural gas to compensate for an earlier combustion event of said gaseous fuel mixture due to reduced ignition delay. 15. A diesel cycle internal combustion engine capable of being fuelled with a gaseous fuel mixture comprising methane and between 5% and 60% hydrogen by volume at standard temperature and pressure, said engine comprising: a combustion chamber defined by a cylinder, a cylinder head, and a piston movable within said cylinder;at least one fuel injection valve with a nozzle that is disposed within said combustion chamber, said fuel injection valve being operable to introduce fuel directly into said combustion chamber;a pressurizing device and piping for delivering said gaseous fuel mixture to said injection valve with a ratio of fuel rail to peak in-cylinder pressure being at least 1.5:1 for at least one engine operating condition; andan electronic controller in communication with an actuator for said fuel injection valve for controlling timing for operating said fuel injection valve;whereby the start of fuel injection timing for said gaseous fuel mixture is adjusted compared to start of fuel injection timing for methane to compensate for an earlier combustion event of said gaseous fuel mixture due to reduced ignition delay. 16. The engine of claim 15 wherein said engine has a compression ratio of at least 14:1. 17. The engine of claim 13 further comprising a second fuel injection valve that is operable to introduce a pilot fuel directly into said combustion chamber. 18. The engine of claim 13 further comprising an ignition plug disposed within said combustion chamber that is operable to assist with ignition of the gaseous fuel mixture. 19. The engine of claim 13 wherein said injection valve is operable to introduce said gaseous fuel mixture directly into said combustion chamber. 20. The engine of claim 13 wherein said at least one fuel injection valve comprises: a first fuel injection valve with a nozzle disposed within said combustion chamber, wherein said fuel injection valve is operable to introduce methane directly into said combustion chamber;a second fuel injection valve with a nozzle disposed within an intake air manifold, wherein said second fuel injection valve is operable to introduce hydrogen into said intake air manifold from which said hydrogen can flow into said combustion chamber; andwherein said electronic controller is in communication with an actuator for each one of said first and second fuel injection valves for controlling respective timing for operating said first and second fuel injection valves. 21. The engine of claim 13 further comprising; a first storage vessel within which hydrogen can be stored;a first valve associated with said first storage vessel and operable for controlling a proportion of hydrogen in said gaseous fuel mixture;a second storage vessel within which methane can be stored;a second valve associated with said second storage vessel and operable for controlling a proportion of methane in said gaseous fuel mixture;whereby in response to detected engine operating conditions respective proportions of hydrogen and methane in said gaseous fuel mixture are changed to predetermined amounts. 22. The engine of claim 21 wherein for each respective gaseous fuel mixture the start of fuel injection timing for said gaseous fuel mixture is adjusted compared to start of fuel injection timing for methane to compensate for an earlier combustion event of the said gaseous fuel mixture due to reduced ignition delay. 23. The engine of claim 21 wherein said second storage vessel stores hydrogen in addition to methane in a predetermined proportion. 24. The engine of claim 15, wherein the gaseous fuel mixture comprises natural gas and the start of fuel injection timing for said gaseous fuel mixture is adjusted compared to start of fuel injection timing for natural gas to compensate for an earlier combustion event of said gaseous fuel mixture due to reduced ignition delay.