Claims:We Claim:
1. A fuel injector (10) for an engine, said fuel injector (10) comprising:
a fuel passageway (12) positioned within said fuel injector (10), said fuel passageway adapted to supply pressurized fuel to a nozzle (13) of said fuel injector;
at least one bellow (14) in flow communication with said fuel passageway (12), said at least one bellow (14) adapted to store fuel therein; characterized in that
at least one constriction (16) in flow communication upstream from said at least one bellow (14), said at least one constriction (16) adapted to restrict the flow of fuel from said at least one bellow (14); and
at least one cavity (18) positioned upstream from said at least one constriction (16), said at least one cavity (18) adapted to store fuel that is channeled through said at least one constriction (16) via said fuel passageway (12).

2. The fuel injector (10) in accordance with claim 1 wherein said at least one cavity (18) is an L-shaped cavity.

, Description:Field of the invention
[0001] This invention relates to a fuel injector for an engine.

Background of the invention
[0002] WO 11085858 A1 relates to a fuel injector apparatus, serving in particular for air-sealing, self-igniting internal combustion engines, having a high pressure input, a first fuel injection valve and at least one other fuel injection valve. According to the invention, fuel can be conducted at least directly into a fuel chamber of the first fuel injection valve via the high pressure input, wherein the other fuel injection valve is connected to the first fuel injection valve via a line and wherein fuel can be conducted via the lines out of the fuel chamber of the first fuel injection valve into a fuel chamber of the other fuel injection valve. To damp pressure pulsations, the fuel chambers of the fuel injection valves accommodate a total fuel volume which comprises a partial volume for fuel injection and at least one additional partial volume for enabling damping.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a fuel injector for an engine.

Detailed description of the invention
[0004] Figure 1 illustrates a fuel injector 10 for an engine. More specifically, a fuel injector 10 for an engine is described. The fuel injector 10 comprises a fuel passageway 12 positioned within the fuel injector 10, the fuel passageway adapted to supply pressurized fuel to a nozzle of the fuel injector. The fuel injector further comprises at least one bellow 14 in flow communication with the fuel passageway 12, the at least one bellow 14 adapted to store fuel therein. At least one constriction 16 is in flow communication upstream from the at least one bellow 14, the at least one constriction 16 adapted to restrict the flow of fuel from the at least one bellow 14. At least one cavity 18 is positioned upstream from the at least one constriction 16, the at least one cavity 18 adapted to store fuel that is channeled through the at least one constriction 16 via the fuel passageway 12.
[0005] The fuel injector 10 for an engine comprises a fuel passageway 12 that is positioned within the fuel injector 10. The fuel passageway 12 channels fuel from an inlet of the fuel injector 10 to a nozzle 13 of the fuel injector 10 for injection to an engine. At least one bellow 14 is coupled in flow communication with the fuel passageway 12 and is adapted to store fuel before supplying the fuel through the fuel passageway 12.
[0006] In an exemplary embodiment, at least one constriction 16 is coupled in flow communication with the at least one bellow 14. The at least one constriction 16 is adapted to control the flow of fuel from and to the at least one bellow 14. At least one cavity 18 is coupled in flow communication with the at least one constriction 16. The at least one cavity 18 is adapted to receive pressurized fuel from the at least one bellow 14 when the pressure of fuel in the at least one bellow 14 is greater than the pressure of fuel in the at least one cavity 18. In addition, the at least one cavity 18 is adapted to supply pressurized fuel to the at least one bellow 14 when the pressure of fuel in the at least one cavity 18 is greater than the pressure of fuel in the at least one bellow 14. The constriction 16 is adapted to resist the movement of fuel from and to the at least one cavity 18. An injector needle 15 is adapted to reciprocate within the fuel injector 10 such that the fuel passageway 12 surrounds the injector needle 15.
[0007] A working of the fuel injector 10 is described as an example. When the injector needle 15 moves in the upward direction away from the nozzle 13 during pilot injection, the fuel from the at least one cavity 18 flows towards the at least one bellow 14 via the at least one constriction 16. From the at least one bellow 14, the pressurized fuel is delivered to the nozzle 13 and therein discharged to the engine. As a consequence, the level of fuel in the at least one cavity 18 decreases. When the injector needle 15 moves in the downward direction to close the opening of the nozzle 13, fuel stops flowing out of the at least one cavity 18. Therein, fresh fuel from the inlet of the fuel injector is channeled via a fuel supply line 19 to the at least one below 14. The fuel that fills in the at least one bellow 14 is at a higher pressure than the fuel that is present in the at least one cavity 18. Therefore, the pressurized fuel flows from the at least one bellow 14 to the at least one cavity 18 via the constriction 16, thereby filling up the at least one cavity 18 with fuel. As the injector needle moves in the downward direction, thereby closing the nozzle 13 a pressure wave is created in the fuel passageway 12. The pressure wave flows through the fuel passageway 12 towards the at least one bellow 14 where the pressure wave is damped. As the pressure wave crosses the at least one bellow 14 towards the at least one constriction 16, the pressure wave is damped even further. Finally, when the pressure wave crosses through the constriction 16 and into the at least one cavity 18, the pressure wave is completely damped due to the fuel present in the at least one cavity 18. Thereby, the injection needle 15 may be raised almost immediately to begin the main injection event as the pressure wave of the previous injection event has been fully damped at the end of the pilot injection event.
[0008] It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with regard to leverage and dimensions of various levers are envisaged and form a part of this invention. The scope of the invention is only limited by the claims.