Claims:We Claim:
1. A high pressure fuel pump (10), said high pressure fuel pump (10) comprising:
a housing (12);
a pumping chamber (14) defined within said housing (12);
a first opening (16) and a second opening (18) defined through said housing (12), said first opening (16) having a smaller diameter than said second opening (18), and wherein said first opening (16) and said second opening (18) adapted to supply pressurized fuel to the pumping chamber (14) of said high pressure fuel pump (10); characterized in that
a plunger (20) positioned within said housing (12), said plunger (20) comprising:
a first vertical groove (22) and a first horizontal groove (24) in flow communication with said first vertical groove (22), said first vertical groove (22) defined along a sidewall of said plunger (20); and
a second vertical groove (26) and a second angular groove (28) in flow communication with said second vertical groove (26), said second vertical groove (26) defined along said sidewall of said plunger (20).

2. The high pressure fuel pump (10) in accordance with Claim 1 wherein said first opening (16) is aligned with said first horizontal groove (24) as the plunger (20) translates toward the top dead centre to facilitate discharging fuel from said first horizontal groove (24) to an outlet of said high pressure fuel pump (10) via said first opening (16).

3. The high pressure fuel pump (10) in accordance with Claim 1 wherein said second opening (18) is aligned with said second angular groove (28) as the plunger (20) translates towards the top dead centre to facilitate discharging fuel from said second angular groove (28) to an outlet of said high pressure fuel pump (10) via said second opening (18).

4. The high pressure fuel pump (10) in accordance with Claim 1 wherein a pre-stroke of said plunger (20) occurs resulting in a partial delivery of fuel from said high pressure fuel pump (10) until said first opening (16) is aligned with said first horizontal groove (24).

5. The high pressure fuel pump (10) in accordance with Claim 1 wherein a main stroke of said plunger (20) occurs resulting in a complete delivery of fuel from said high pressure fuel pump (10) until said second opening (18) is aligned with said second angular groove (28).

6. A plunger (20) for a high pressure fuel pump (10), said plunger (20) comprising:
a first vertical groove (22) and a first horizontal groove (24) in flow communication with said first vertical groove (22), said first vertical groove (22) defined along a sidewall of said plunger (20); and
a second vertical groove (26) and a second angular groove (28) in flow communication with said second vertical groove (26), said second vertical groove (26) defined along said sidewall of said plunger (20).
, Description:Field of the invention
[0001] This invention relates to a high pressure fuel pump and more specifically to pre-injection for a port controlled high pressure fuel pump.

Background of the invention
[0002] GB 784948 A describes dough pieces on a conveyer that are sprayed before baking with liquid fat intermittently delivered by spraying nozzles connected respectively to the cylinders of a multi-cylinder pump and the operation of the latter is so timed, in relation to the speed of the conveyer, that each dough piece is subjected to several collective discharges while passing the spraying nozzles. Conveyer belt is carried on rollers journalled in brackets and its top run extends flush with the top of casing and is supported on flat strips or small rollers. One roller is driven through gearing including reduction gear-box by an electric motor. The output shaft of gear-box is connected by a chain (or belt) to the shaft of a high pressure pump. Edible fat is contained in a tank heated by a thermostatically-controlled electric heater and flows through a pipe to the intake of pump which has three plungers working in three cylinders each connected by a pipe to a nozzle. Each pump cylinder communicates with a common suction chamber through inlet ports which are shut off during the latter part of the delivery stroke, the trapped oil having access to a circumferential helical groove so that, at a point determined by the angular position of the plunger, it uncovers one of the inlet ports and terminates delivery by allowing oil to return to the suction chamber. The output is controlled by rotating the plungers by a rack-rod. Means are provided on each nozzle for altering the type of discharge produced. The dough pieces are placed on the conveyer at its right-hand end and travel through a sheet-metal tunnel to a hood containing the nozzles and thence to a second tunnel.

Brief description of the accompanying drawings
[0003] Figure 1 illustrates a schematic diagram of a high pressure fuel pump.
[0004] Figure 2 illustrates a schematic diagram of a plunger of the high pressure fuel pump.

Detailed description of the invention
[0005] A high pressure fuel pump 10 is described. The high pressure fuel pump 10 comprises a housing 12 and a pumping chamber 14 defined within the housing 12. A first opening 16 and a second opening 18 are defined through the housing 12, the first opening 16 having a smaller diameter than the second opening 18, and wherein the first opening 16 and the second opening 18 are adapted to supply pressurized fuel to the pumping chamber 14 of the high pressure fuel pump 10. A plunger 20 is positioned within the housing 12, the plunger 20 comprising a first vertical groove 22 and a first horizontal groove 24 in flow communication with the first vertical groove 22, the first vertical groove 22 defined along a sidewall of the plunger 20. A second vertical groove 26 and a second angular groove 28 is in flow communication with the second vertical groove 26, the second vertical groove 26 defined along the sidewall of the plunger 20.
[0006] Figure 1 illustrates a schematic diagram of a high pressure fuel pump 10. The high pressure fuel pump 10 comprises a housing 12. The housing 12 comprises an outer sidewall 13, an inner sidewall 15 and a solid surface defined between the outer sidewall 13 and the inner sidewall 15. The inner sidewall 15 of the housing 12 surrounds a pumping chamber 14. A first opening 16 and a second opening 18 are defined through the solid surface of the housing 12 and extends from the outer sidewall 13 to the inner sidewall 15. The first opening 16 and the second opening 18 are each adapted to deliver pressurized fuel from an external source to the pumping chamber 14 of the high pressure fuel pump 10. In addition, the first opening 16 and the second opening 18 are each adapted to supply pressurized fuel from the pumping chamber 14 out of the high pressure fuel pump 10. In an exemplary embodiment, the first opening 16 has a diameter that is smaller than a diameter of the second opening 18 to facilitate channeling a smaller quantity of fuel within the pumping chamber 14 of the high pressure fuel pump 10. In an alternate exemplary embodiment, the first opening 16 has a diameter that is equal to the diameter of the second opening 18. A plunger 20 is positioned within the pumping chamber 14 of the high pressure fuel pump 10 such that the plunger 20 reciprocates within the pumping chamber 14 of the high pressure fuel pump 10.
[0007] Figure 2 illustrates a schematic diagram of a plunger 20 of the high pressure fuel pump. The plunger 20 of the high pressure fuel pump includes the first opening 16 and the second opening 18 that are each defined through the solid surface of the housing 12. The first opening 16 and the second opening 18 are each adapted to supply fuel to the pumping chamber 14 and withdraw fuel out of the pumping chamber 14 of the high pressure fuel pump. The plunger 20 comprises a first vertical groove 22 and a first horizontal groove 24 that is in flow communication with the first vertical groove 22. The first vertical groove 22 is defined along a sidewall of the plunger 20 and receives fuel from the pumping chamber 14 of the high pressure fuel pump. From the first vertical groove 22, the fuel is channeled to the first horizontal groove 24 and fills the first horizontal groove 24. The plunger 20 comprises the second vertical groove 26 and the second angular groove 28 that is in flow communication with the second vertical groove 26. The second vertical groove 26 is defined along the sidewall of the plunger 20 and receives fuel from the pumping chamber 14 of the high pressure fuel pump. From the second vertical groove 26, the fuel is channeled to the second angular groove 28. When the plunger 20 translates from the bottom dead center to the top dead center position, the first horizontal groove 24 comes in alignment with the first opening 16 and the second angular groove 28 comes in alignment with the second opening 18 at different time intervals, thereby causing the pressurized fuel from the pumping chamber 14 to be discharged out of the high pressure fuel pump via the first opening 16 and the second opening 18 respectively at a first time interval and a second time interval respectively.
[0008] A working of the high pressure fuel pump 10 is described as an example. Pressurized fuel from a low pressure fuel pump is supplied to the pumping chamber 14 of the high pressure fuel pump 10 via the first opening 16 and the second opening 18 respectively. From the pumping chamber 14, the pressurized fuel is channeled to the first horizontal groove 24 and the second angular groove 28 via the first vertical groove 22 and the second vertical groove 26 respectively. As the plunger 20 begins translating from the bottom dead center to the top dead center, the first opening 16 and the second opening 18 are covered by the sidewall of the plunger 20. Therein, the pressurized fuel in the pumping chamber 14 of the high pressure fuel pump is delivered to the fuel injector. From the fuel injector, the pressurized fuel is injected into the engine which leads to pre-injection of the fuel into the engine. When the plunger 20 of the high pressure fuel pump translates further, the first opening 16 is in flow communication with the first horizontal groove 24 that is defined along the sidewall of the plunger 20. Therein, the pressurized fuel is channeled from the first horizontal groove 24 out of the high pressure fuel pump 10 via the first opening 16. Due to the decrease in the pressure of fuel in the pumping chamber 14 of the high pressure fuel pump 10, fuel delivery from the high pressure fuel pump to the fuel injector ceases.
[0009] As the plunger 20 continues to translate towards the top dead center, the first horizontal groove 24 surpasses the first opening 16, thereby covering the first opening 16. Therein, the pressurized fuel in the pumping chamber 14 of the high pressure fuel pump is delivered to the fuel injector. From the fuel injector, the pressurized fuel is injected into the engine which leads to main injection of the fuel into the engine. When the plunger 20 of the high pressure fuel pump translates further, the second opening 18 is in flow communication with the second angular groove 20. Therein, the pressurized fuel is channeled from the second angular groove 28 out of the high pressure fuel pump 10 via the second opening 18. Due to the decrease in the pressure of fuel in the pumping chamber 14 of the high pressure fuel pump 10, fuel delivery from the high pressure fuel pump to the fuel injector ceases.
[0010] 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 components are envisaged and form a part of this invention. The scope of the invention is only limited by the claims.