초록 ▼

A dual fuel system includes liquid and gaseous fuel supplies and a fuel injector in fluid communication therewith. A gaseous fuel check in the fuel injector forms a leak path with a fuel injector body between gaseous and liquid fuel passages, and a leakage limiting seal is positioned about the gaseo

A dual fuel system includes liquid and gaseous fuel supplies and a fuel injector in fluid communication therewith. A gaseous fuel check in the fuel injector forms a leak path with a fuel injector body between gaseous and liquid fuel passages, and a leakage limiting seal is positioned about the gaseous fuel check and deformable into sealing contact with the gaseous fuel check responsive to an increase in a pressure drop from the liquid fuel passage to the gaseous fuel passage in the fuel injector.

대표청구항 ▼

1. A dual fuel system for an internal combustion engine comprising: a liquid fuel supply;a gaseous fuel supply;a fuel injector including an injector body defining a liquid fuel passage in fluid communication with the liquid fuel supply, a gaseous fuel passage in fluid communication with the gaseous

1. A dual fuel system for an internal combustion engine comprising: a liquid fuel supply;a gaseous fuel supply;a fuel injector including an injector body defining a liquid fuel passage in fluid communication with the liquid fuel supply, a gaseous fuel passage in fluid communication with the gaseous fuel supply, and a gaseous fuel nozzle outlet;the fuel injector further including a gaseous fuel check guided within the injector body between retracted and advanced positions at which fluid communication is open and blocked, respectively, between the gaseous fuel passage and the gaseous fuel nozzle outlet, and the injector body and the gaseous fuel check together forming a leak path for controlled leakage of liquid fuel from the liquid fuel passage to the gaseous fuel passage responsive to a pressure drop therebetween; andthe fuel injector further including a leakage limiting seal having an outer surface exposed to a fluid pressure of the liquid fuel passage, an inner surface exposed to a fluid pressure of the leak path, and being positioned about the gaseous fuel check such that the leakage limiting seal deforms into sealing contact with the gaseous fuel check responsive to an increase in the pressure drop. 2. The dual fuel system of claim 1 further comprising a gaseous fuel common rail fluidly connecting the gaseous fuel supply to the gaseous fuel passage, and a liquid fuel common rail fluidly connecting the liquid fuel supply with the liquid fuel passage, and wherein the injector body defines a liquid fuel nozzle outlet and a liquid fuel check guided within the injector body between retracted and advanced positions at which fluid communication is open and blocked, respectively, between the liquid fuel passage and the liquid fuel nozzle outlet. 3. The dual fuel system of claim 2 wherein each of the gaseous fuel check and the liquid fuel check includes an opening hydraulic surface exposed to a fluid pressure of the liquid fuel passage. 4. The dual fuel system of claim 3 wherein the outer surface of the leakage limiting seal extends circumferentially around the gaseous fuel check at a radially outward location, and the inner surface extends circumferentially around the gaseous fuel check at a radially inward location, such that the leakage limiting seal is configured to deform in a radially inward direction. 5. The dual fuel system of claim 4 wherein the injector body further includes a tip piece defining a first and a second guide bore receiving the gaseous fuel check and the liquid fuel check, respectively, and having each of the liquid fuel nozzle outlet and the gaseous fuel nozzle outlet formed therein. 6. The dual fuel system of claim 5 wherein the leakage limiting seal includes a floating seal abutting the tip piece. 7. The dual fuel system of claim 6 wherein the leakage limiting seal includes a first axial end, and a second axial end abutting the tip piece and having an annular knife edge. 8. The dual fuel system of claim 5 wherein the leakage limiting seal is resident within the tip piece. 9. The dual fuel system of claim 8 wherein the leakage limiting seal includes a sleeve formed integrally with the tip piece. 10. A fuel injector for a dual fuel system in an internal combustion engine comprising: an injector body defining a liquid fuel passage extending between a liquid fuel inlet and a liquid fuel outlet, and a gaseous fuel passage extending between a gaseous fuel inlet and a gaseous fuel nozzle outlet;a gaseous fuel check guided within the injector body between retracted and advanced positions at which fluid communication is open and blocked, respectively, between the gaseous fuel passage and the gaseous fuel nozzle outlet, for controlling injection of gaseous fuel from the gaseous fuel nozzle outlet into a cylinder in the internal combustion engine, and the injector body and the gaseous fuel check together forming a leak path from the liquid fuel passage to the gaseous fuel passage;a leakage limiting seal having an outer surface exposed to a fluid pressure of the liquid fuel passage, and an inner surface exposed to a fluid pressure of the leak path; andthe leakage limiting seal being in a first state where the inner surface has a clearance with the gaseous fuel check and permits controlled leakage of the liquid fuel through the leak path, and being deformable to a second state at which the inner surface is in sealing contact with the gaseous fuel check to limit the leakage, responsive to an increase in a pressure drop from the liquid fuel passage to the gaseous fuel passage. 11. The fuel injector of claim 10 wherein the outer surface of the leakage limiting seal extends circumferentially around the gaseous fuel check at a radially outward location, and the inner surface extends circumferentially around the gaseous fuel check at a radially inward location, such that in the second state the leakage limiting seal is deformed in a radially inward direction. 12. The fuel injector of claim 11 wherein the sealing contact includes metal-to-metal contact. 13. The fuel injector of claim 11 wherein the injector body further defines a guide bore receiving the gaseous fuel check, and wherein the clearance includes a lesser clearance and the gaseous fuel check has a greater clearance with the injector body within the guide bore. 14. The fuel injector of claim 10 wherein the liquid fuel outlet includes a liquid fuel nozzle outlet, and further comprising a liquid fuel check guided within the injector body between retracted and advanced positions at which fluid communication is open and blocked, respectively, between the liquid fuel passage and the liquid fuel nozzle outlet. 15. The fuel injector of claim 14 wherein the injector body further includes a tip piece defining a first and a second guide bore receiving the gaseous fuel check and the liquid fuel check, respectively, and having each of the liquid fuel nozzle outlet and the gaseous fuel nozzle outlet formed therein. 16. The fuel injector of claim 15 wherein the leakage limiting seal includes a floating seal abutting the tip piece. 17. The fuel injector of claim 15 wherein the leakage limiting seal is formed integrally with the tip piece. 18. A method of limiting migration of liquid fuel to a gaseous fuel side of a dual fuel system in an internal combustion engine comprising the steps of: increasing a pressure drop from a liquid fuel passage to a gaseous fuel passage in fluid communication with one another via a leak path formed by a gaseous fuel check and an injector body in a fuel injector of the dual fuel system;deforming a leakage limiting seal into sealing contact with the gaseous fuel check, responsive to the increase in the pressure drop; andreducing leakage of liquid fuel through the leak path via the sealing contact. 19. The method of claim 18 wherein the step of deforming further includes deforming the leakage limiting seal such that a clearance between an inner surface of the leakage limiting seal exposed to a fluid pressure of the leak path and the gaseous fuel check is reduced.