초록 ▼

Described herein are various embodiments of an apparatus, system and method for operating a dual fueled spark ignition engine. For example, according to one illustrative embodiment, a method for operating a dual fueled spark ignition engine includes fueling the engine solely with a combustion promot

Described herein are various embodiments of an apparatus, system and method for operating a dual fueled spark ignition engine. For example, according to one illustrative embodiment, a method for operating a dual fueled spark ignition engine includes fueling the engine solely with a combustion promoter within a first engine load range between zero and an engine load associated with a target combustion condition selected from the group consisting of rough limit, knock limit, and any of various conditions between the rough limit and knock limit. Within the first engine load range, the amount of combustion promoter fueling the engine increases as the load increases. The method further includes fueling the engine on a mixture of ammonia and the combustion promoter within a second engine load range between the engine load associated with the selected target combustion condition and the engine load associated with a maximum operating pressure of the engine. Within the second engine load range, the amount of ammonia fueling the engine increases and the amount of combustion promoter fueling the engine remains substantially constant as the load increases.

대표청구항 ▼

What is claimed is: 1. A dual fueled spark ignition internal combustion engine, comprising: an engine intake line coupled to at least one combustion chamber; an air intake system in air supplying communication with the engine intake line; a fuel delivery system comprising a first ammonia source and

What is claimed is: 1. A dual fueled spark ignition internal combustion engine, comprising: an engine intake line coupled to at least one combustion chamber; an air intake system in air supplying communication with the engine intake line; a fuel delivery system comprising a first ammonia source and a second combustion promoter source separate from the first ammonia source, the first ammonia source communicable in ammonia supplying communication with the engine intake line and the second combustion promoter source communicable in combustion promoter supplying communication with the engine intake line; and an electronic control module operable in a dual fuel mode to control the flow rate of ammonia and combustion promoter into the engine intake line to achieve substantially stoichiometric combustion of air, ammonia and combustion promoter in the combustion chamber for each cycle of the internal combustion engine; wherein when in the dual fuel mode, the ratio of ammonia to combustion promoter combusted in the combustion chamber increases as the engine load increases. 2. The internal combustion engine of claim 1, wherein the electronic control module is operable to control the flow of rate ammonia and combustion promoter into the engine intake to operate the engine at a desired operational state between a rough limit and a knock limit, wherein the ratio of ammonia to combustion promoter at the rough limit is higher than the ratio of ammonia to combustion promoter at the knock limit at a given engine load. 3. The internal combustion engine of claim 2, wherein the desired operational state of the engine is at least partially determined by at least one factor selected from the group consisting of operator desire, cost of ammonia, cost of combustion promoter, availability of ammonia, availability of combustion promoter, and overall engine efficiency. 4. The internal combustion engine of claim 1, wherein as the load increases the amount of combustion promoter combusted in the combustion chamber remains substantially constant, and amount of ammonia combusted in the combustion chamber increases per engine cycle. 5. The internal combustion engine of claim 4, further comprising an exhaust gas oxygen sensor electrically coupled to the electronic control module, wherein the amount of ammonia combusted in the combustion chamber is at least partially determined by the net balance between the oxidizer and reducer in the exhaust gas as sensed by the exhaust gas oxygen sensor. 6. The internal combustion engine of claim 1, wherein the electronic control module is operable to control a combustion spark advance of the internal combustion engine, and wherein when the ratio of ammonia to combustion promoter is greater than zero, the spark advance is held substantially constant as the operation load of the engine increases. 7. The internal combustion engine of claim 1, wherein the electronic control module is further operable in a single fuel mode to reduce the flow rate of ammonia to zero to achieve substantially stoichiometric combustion of only air and combustion promoter in the combustion chamber per cycle at each operating load of the internal combustion engine, wherein the maximum operating load of the engine in the dual fuel mode is higher than the maximum operating load of the engine in the single fuel mode. 8. The internal combustion engine of claim 1, wherein the combustion promoter is selected from the group consisting of gasoline and other hydrocarbons, alcohols, and hydrogen. 9. The internal combustion engine of claim 1, wherein an amount of harmful exhaust emissions produced by the engine in the dual fuel mode are lower than the harmful exhaust emissions produced by the engine if fueled solely with the combustion promoter. 10. The internal combustion engine of claim 1, wherein in the dual fuel mode the engine is operable at a dual fuel engine operating efficiency per cycle at a given load, and wherein the dual fuel engine operating efficiency is higher than a single fuel engine operating efficiency achieved by operating the engine solely on the combustion promoter. 11. An internal combustion engine system, comprising: a spark ignition internal combustion engine operable at any of various combustion conditions between a rough limit and a knock limit in a single fuel mode and a dual fuel mode, wherein in the single fuel mode the fuel is a combustion promoter and in the dual fuel mode the fuel is a mixture of ammonia and said combustion promoter; a fuel metering module operable to control the flow rate of ammonia and the flow rate of combustion promoter into the engine such that the mixture of ammonia and combustion promoter has a calculated ratio of ammonia to combustion promoter determinable from an operating map of the engine, wherein the fuel metering module is operable to increase the ratio of ammonia to combustion promoter of the mixture with increasing engine load and decrease the ratio of ammonia to combustion promoter of the mixture with decreasing engine load to achieve substantially stoichiometric operation across the entire engine load range of the internal combustion engine; an air metering module operable to control the mass flow rate of air into the engine; and a spark advance module operable to control the spark advance of an ignition spark for igniting the fuel; wherein the engine automatically switches from the single fuel mode to the dual fuel mode when an engine load corresponding to a target combustion condition is reached. 12. The internal combustion engine system of claim 11, wherein the rough limit corresponds to a coefficient of variation of a net indicated mean effective pressure of the engine of less than about 5%. 13. The internal combustion engine system of claim 11, wherein in the dual fuel mode, the spark advance module is operable to increase or hold the spark advance substantially constant as the engine load increases. 14. The internal combustion engine system of claim 11, wherein in the dual fuel mode, the fuel metering module is operable to hold the flow rate of combustion promoter substantially constant for a given RPM of the engine. 15. The internal combustion engine system of claim 14, wherein in the dual fuel mode, the fuel metering module is operable to increase the flow rate of ammonia into the engine as the engine load increases and decrease the flow rate of ammonia into the engine as the engine load decreases. 16. The internal combustion engine system of claim 11, wherein as the RPM of the engine increases when operating in the dual fuel mode, the fuel metering module is operable to decrease the ammonia to combustion promoter ratio of the mixture by increasing the flow rate of combustion promoter into the engine on a per cycle basis. 17. The internal combustion engine system of claim 11, wherein the internal combustion engine has a compression ratio between about 8:1 and about 12:1. 18. The internal combustion engine system of claim 11, wherein the difference between the engine load at which the engine operating at a first compression ratio and the rough limit switches between the single fuel mode and the dual fuel mode and the engine load at which the engine operating at a second compression different than the first compression ratio and the rough limit is less than the difference between the engine load at which the engine operating at the first compression ratio and the knock limit switches between the single fuel mode and the dual fuel mode and the engine load at which the engine operating at the second compression ratio and the knock limit switches between the single fuel mode and the dual fuel mode. 19. A method for operating a dual fueled spark ignition engine, comprising: fueling the engine solely with a combustion promoter within a first engine load range between zero and an engine load associated with a target combustion condition selected from the group consisting of rough limit, knock limit, and any of various conditions between the rough limit and knock limit, wherein the amount of combustion promoter fueling the engine increases as the load increases within the first engine load range; and fueling the engine on a mixture of ammonia and the combustion promoter within a second engine load range between the engine load associated with the selected target combustion condition and the engine load associated with a maximum operating pressure of the engine, wherein the amount of ammonia fueling the engine increases and the amount of combustion promoter fueling the engine remains substantially constant as the load increases within the second engine load range. 20. The method of claim 19, further comprising: decreasing a spark advance of the engine as the load increases within the first engine load range; and holding the spark advance of the engine substantially constant as the load increases within a substantial portion of the second engine load range. 21. The method of claim 19, wherein fueling the engine on a mixture of ammonia and the combustion promoter comprises stoichiometrically combusting the mixture of ammonia and the combustion promoter. 22. The method of claim 19, wherein the target combustion condition comprises the rough limit, and wherein the rough limit is reached at a predetermined engine load that increases as the RPM of the engine increases. 23. The method of claim 19, wherein a ratio of ammonia to combustion promoter of the mixture at the rough limit is higher than the ratio of ammonia to combustion promoter of the mixture at the knock limit. 24. The method of claim 19, wherein fueling the engine on a mixture of ammonia and the combustion promoter comprises introducing the ammonia into the engine from a first ammonia source and introducing the combustion promoter into the engine from a second combustion promoter source separate from the first ammonia source, and wherein the introduction of ammonia into the engine is separate from the introduction of the combustion promoter into the engine. 25. The method of claim 19, wherein the spark ignition engine comprises an exhaust gas oxygen sensor coupled to an exhaust system of the engine, the method further comprising: when the engine is operating within the first engine load range, controlling the flow rate of the combustion promoter based at least partially on input from the exhaust gas oxygen sensor; and when the engine is operating within the second engine load range, controlling the flow rate of the ammonia based at least partially on input from the exhaust gas oxygen sensor.