This disclosure relates generally to a fuel system and more particularly to an improved fuel system for an internal combustion engine.
Due to the rising costs of liquid fuel (e.g. diesel fuel) and ever increasing restrictions on exhaust emission, engine manufactures have developed dual-fuel engines. An exemplary dual-fuel engine provides a low-cost gaseous fuel (e.g. natural gas) through air intake ports of the engine's cylinders. The gaseous fuel is introduced with clean air that enters through the intake ports and is ignited by liquid fuel that is injected during each combustion cycle. Because a lower-cost fuel is used together with liquid fuel, cost efficiency may be improved. In addition, the combustion of the gaseous and liquid fuel mixture may result in a reduction of harmful emissions.
An example of this type of arrangement is disclosed in U.S. Pat. No. 4,527,516 to Foster. In particular, the '516 patent discloses a dual-fuel engine that includes an inlet pipe connected at one end to a gas source and at opposite end to the side of an engine via an inlet port. The pipe is held in the inlet port by a port seal, such that an upper edge of the pipe is spaced below an upper edge of the inlet port. The '516 patent also optionally includes an electronically controlled gas admission valve to control the timing of the gas entry into the cylinder via the inlet pipe. Additionally, typically, the gas fuel injector that supplies gas to the engine cylinder liner is located in close proximity to the cylinder liner. However, the cylinder liner is exposed to high temperature and pressure conditions during the combustion process and may cause the gaseous fuel injector to deteriorate.
The disclosed fuel system is directed at overcoming one or more problems of the prior art.
In one aspect of the present disclosure, an improved fuel system for an internal combustion engine is disclosed. The fuel system includes a liquid fuel injector configured to inject liquid fuel into at least one cylinder and a gaseous fuel injector having a nozzle configured to inject gaseous fuel into at least one cylinder. The gaseous fuel injector is positioned outside an airbox.
In another aspect of the present disclosure, an improved fuel system for an internal combustion engine is disclosed. The fuel system includes a gaseous fuel injector having a nozzle configured to inject gaseous fuel into at least one cylinder. The gaseous fuel injector is positioned outside an airbox.
Within engine cylinder liner 18, piston 24 may be configured to reciprocate between a bottom-dead-center (BDC) or lower-most position and a top-dead-center (TDC) or upper-most position. In particular, piston 24 may be an assembly that includes a piston crown 26 pivotally connected to rod 28, so that a sliding motion of each piston 24 within liner 18 result in a rotation of crankshaft 30. Similarly, a rotation of crankshaft 30 may result is a sliding motion of piston 24. As crankshaft 30 rotates through about 180 degrees, piston crown 26 and connected rod 28 may move through one full stroke between BDC and TDC. Engine 10, being a two-stroke engine, may have a complete cycle that includes a power/exhaust/intake stroke (TDC to BDC) and an intake/compression stroke (BDC to TDC).
During a final phase of the power/exhaust/intake stroke described above, air may be drawn into combustion chamber 22 via one or more gas exchange ports (e.g., air intake ports) 32 located within a sidewall of cylinder liner 18. In particular, as piston 24 moves downward within liner 18, a position will eventually be reached at which air intake ports 32 are no longer blocked by piston 24 and instead are fluidly communicated with combustion chamber 22. When air intake ports 32 are in fluid communication with combustion chamber 22 and a pressure of air at air intake ports 32 is greater than a pressure with combustion chamber 22, air will pass through air intake ports 32 into combustion chamber 22. It is contemplated that gaseous fuel (e.g., methane or natural gas) may be introduced into combustion chamber 22 (radially injected) through at least one of air intake ports 32. The gaseous fuel may mix with the air to form a fuel/air mixture within combustion chamber 22.
Eventually, piston 24 will start an upward movement that blocks air intake ports 32 and compresses the air/fuel mixture. As the air/fuel mixture within combustion chamber 22 compresses, a temperature of the mixture may increase. At a point when piston 24 is near TDC, a liquid fuel (e.g. diesel or other petroleum-based liquid fuel) may be injected into combustion chamber 22 via a liquid fuel injector 36.
The liquid fuel may be ignited by the hot air/fuel mixture, causing combustion of both types of fuel and resulting in a release of chemical energy in the form of temperature and pressure spikes within combustion chamber 22. During a first phase of the power/exhaust/intake stroke, the pressure spike within combustion chamber 22 may force piston 24 downward, thereby imparting mechanical power to crankshaft 30. At a particular point during this downward travel, one or more gas exchange ports (e.g., exhaust ports) 34 located within cylinder head 20 may open to allow pressurized exhaust within combustion chamber 22 to exit and the cycle will restart.
Liquid fuel injector 36 may be positioned inside cylinder head 20 and configured to inject liquid fuel into a top of combustion chamber 22 by releasing fuel axially towards an interior of cylinder liner 18 in a generally cone-shaped pattern. Liquid fuel injector 36 may be configured to cyclically inject a fixed amount of liquid fuel, for example, depending on a current engine speed and/or load. In one embodiment, engine 10 may be arranged to run on liquid fuel injections alone or a smaller amount of liquid fuel mixed with a gaseous fuel. Gaseous fuel may be injected through air intake port 32 via any number of gaseous supply lines 37 that are connected to gaseous fuel injectors 38. The gaseous fuel may be injected radially into combustion chamber 22 through a corresponding air intake port 32 after the air intake port 23 may be opened by movement of piston 24.
The gaseous fuel injector 38 may be positioned outside an airbox 40. The airbox 40 serves as a source of air to be introduced to at least one cylinder 16 during the combustion process. An inlet end 41 of the gaseous fuel supply line 37 connects to the gaseous fuel injector 38 and an outlet end 43 of the gaseous fuel supply line 37 connects to and seals the cylinder liner 18. The outlet end 43 is in direct communication with one of the air intake ports 32 of an adjacent engine cylinder 16. A non-return valve 42 is positioned within the gaseous fuel supply line 37. The non-return valve is distally located from the inlet end 41 of the gaseous fuel supply line 37 to prevent backflow of exhaust gas into the gas manifold 45. Alternatively, the non-return valve 42 may be distally located from the outlet end 43 of the gaseous fuel supply line 37 to prevent backflow of exhaust gas into the gas manifold 45 (not shown). Further, the gaseous fuel injector 38 as depicted in
Engine 10, utilizing fuel system 14, may consume two types of fuels when it is run as a dual-fuel engine. It is contemplated that the gaseous fuel may produce between 40% and 85% of a total energy output of engine 10. For example, the gaseous fuel may produce between 60% and 65% of the total output, with the liquid fuel producing the remaining 35-40%. In any case, the liquid fuel can act as an ignition source such that a smaller amount will be necessary than what is needed for engine 10 if it were running on only liquid fuel.
Retrofit kit 80 may additionally include a set of instructions 74 for properly installing the components of kit 80. One of ordinary skill in the art would recognize that retrofit kit 80 of
As an application of the present disclosure, a fuel system 14 for an internal combustion engine 10 is used to provide fuel. Typically, in fuel systems, dual-fuel engines are used to provide injections of low-cost gaseous fuel into clear air that enters through intake ports of at least one cylinder and is ignited with liquid fuel that is injected during each combustion cycle. Generally, under normal conditions, combustion of the gaseous fuel mixture may result in reduction of harmful emissions. The gaseous fuel injector 38 is used to introduce fuel into the engine 10 via a gaseous supply line 37.
The fuel system for an internal engine 10 having at least one cylinder 16 includes a liquid fuel injector 36 configured to inject liquid fuel into the at least one cylinder 16; a gaseous fuel injector 38 having a nozzle 54 to configured to inject gas in at least one cylinder 16, wherein the gaseous fuel injector 38 is positioned outside of an airbox 40 of at least one cylinder 16.
The gaseous fuel injector 38 is located outside of the airbox 40, thus providing ease of access for service and maintenance.
In the embodiment shown in
Other aspects may be obtained from a study of the drawings, the specification, and the appended claims.