Claims:CLAIMS

We Claim

1. A high pressure fuel pump (10), said high pressure fuel pump (10) comprising:
a housing (12);
a plunger (14) positioned within said housing (12), said plunger (14) adapted to reciprocate within said housing (12);
a vertical groove (16) defined in said plunger (14), the vertical groove (16) adapted to extend along a sidewall of said plunger (14);
a rectangular shaped groove (18) defined in said plunger (14) and in flow communication with the vertical groove (16); characterized in that
a semi-circular shaped groove (20) defined in said plunger (14) and in flow communication with the rectangular shaped groove (18) and the vertical groove (16), the semi-circular shaped groove (20) adapted to receive a semi-circular shaped portion (22) therein.

2. The high pressure fuel pump (10) in accordance with Claim 1, wherein the semi-circular shaped groove (20) comprises a first threaded opening (24) and a second threaded opening (26) defined there through, the first threaded opening (24) and the second threaded opening (26) spaced apart from one another by a predetermined displacement.

3. The high pressure fuel pump (10) in accordance with Claim 2, wherein the semi-circular shaped portion (22) comprises a circular shaped through hole (28) and a kidney bean slot (30) defined there through, the circular shaped through hole (28) aligned with the second threaded opening (26), and the kidney bean slot (30) aligned with the first threaded opening (24).
4. The high pressure fuel pump (10) in accordance with Claim 3, further comprising a first threaded screw (32) inserted through the circular shaped through hole (28) and screwed onto the second threaded opening (26) to facilitate fastening the semi-circular shaped portion (22) within the semi-circular shaped groove (20).

5. The high pressure fuel pump (10) in accordance with Claim 4, further comprising a second threaded screw (34) inserted through the kidney bean slot (30) and screwed onto the first threaded opening (24) to facilitate fastening the semi-circular shaped portion (22) within the semi-circular shaped groove (20).

6. The high pressure fuel pump (10) in accordance with Claim 5, wherein the semi-circular shaped portion (22) is adapted to be rotated to facilitate guiding said second threaded screw (34) within the kidney bean slot (30) to a user required displacement, said second threaded screw (34) screwed onto the first threaded opening (24) to facilitate fastening the semi-circular shaped portion (22) within the semi-circular shaped groove (20) at the user required displacement.

7. The high pressure fuel pump (10) in accordance with Claim 6, wherein the semi-circular shaped portion (22) that is rotated to the user required displacement facilitates setting the angle of the semi-circular shaped portion (22) at a user required angle, thereby facilitating setting the depth at which a bottom edge (35) of the semi-circular shaped portion (22) comes in flow communication with a fuel inlet port to discharge pressurized fuel from the rectangular shaped grove (18) to a fuel gallery via the fuel inlet port.

8. The high pressure fuel pump (10) in accordance with Claim 6, wherein the first threaded screw (32) and the second threaded screw (34) are flush against an outer surface of said plunger (14) to prevent said first threaded screw (32) and said second threaded screw (34) from coming in contact with a barrel of said high pressure fuel pump (10).
, Description: Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001] This invention relates to a high pressure fuel pump, and more specifically to a variable angle helix groove for a plunger of the high pressure fuel pump.

Background of the invention
[0002] IN 202141012954 describes a high pressure fuel pump. The high pressure fuel pump comprises a housing, and a plunger positioned within the housing. The plunger is adapted to reciprocate within the housing. A vertical groove is defined in the plunger, the vertical groove adapted to extend along a sidewall of the plunger. A helix groove is in flow communication with the vertical groove and extends angularly along a sidewall of the plunger, the helix groove having a variable depth that extends across a length of the helix groove.

Brief description of the accompanying drawings
[0003] Figure 1 illustrates a high pressure fuel pump in one embodiment of the invention.
[0004] Figure 2 illustrates a plunger with a variable angle helix groove defined in the plunger of the high pressure fuel pump in another embodiment of the invention.

Detailed description of the embodiments
[0005] A high pressure fuel pump 10 is described. The high pressure fuel pump 10 comprises a housing 12, and a plunger 14 positioned within the housing 12. The plunger 14 is adapted to reciprocate within the housing 12. A vertical groove 16 is defined in the plunger 14, the vertical groove 16 adapted to extend along a sidewall of the plunger 14. A rectangular shaped groove 18 is defined in the plunger 14 and in flow communication with the vertical groove 16. A semi-circular shaped groove 20 is defined in the plunger 14 and in flow communication with the rectangular shaped groove 18 and the vertical groove 16. The semi-circular shaped groove 20 is adapted to receive a semi-circular shaped portion 22 therein.

[0006] Figure 1 illustrates the high pressure fuel pump 10 in one embodiment of the invention. The high pressure fuel pump 10 comprises a housing 12. A plunger 14 is positioned within the housing 12, wherein the plunger 14 is adapted to reciprocate within the housing 12 and translate from the bottom dead center position to the top dead center position. As the plunger 14 translates from the bottom dead center position to the top dead center position, fuel is delivered from the high pressure fuel pump 10 to a fuel injector, and therein supplied to an engine cylinder for combustion. A vertical groove 16 is defined in the plunger 14, wherein the vertical groove 16 is adapted to extend along a sidewall of the plunger 14. The vertical groove 16 is adapted to channel pressurized fuel from the pumping chamber of the high pressure fuel pump 10 to a rectangular shaped groove 18 that is in flow communication with the vertical groove 16. From the rectangular shaped groove 18, the pressurized fuel is discharged from the pumping chamber to the fuel gallery of the high pressure fuel pump 10 via a fuel inlet port (not shown) as will be explained in more detail hereinafter.

[0007] Figure 2 illustrates a plunger 14 with a semi-circular shaped portion 22 defined in the plunger 14 of the high pressure fuel pump 10 in another embodiment of the invention. In an exemplary embodiment, a rectangular shaped groove 18 is defined in the plunger 14. The rectangular shaped groove 18 is in flow communication with the vertical groove 16. A semi-circular shaped groove 20 is defined in the plunger 14 and in flow communication with the rectangular shaped groove 18 and the vertical groove 16 respectively. In the exemplary embodiment, the semi-circular shaped groove 20 is adapted to receive a semi-circular shaped portion 22 therein. In an exemplary embodiment, the semi-circular shaped groove 20 comprises the same depth as that of the rectangular shaped groove 18. In an alternate exemplary embodiment, the semi-circular shaped groove 20 comprises any depth that allows for the semi-circular shaped groove 20 to receive a corresponding semi-circular shaped portion 22 therein such that the semi-circular shaped portion 22 is flush against the outer circumference of the plunger 14 of the high pressure fuel pump 10. Therefore, the semi-circular shaped portion 22 comprises a thickness that is equal to the depth of the semi-circular shaped groove 20 that is defined on the plunger 14 of the high pressure fuel pump 10.

[0008] In an exemplary embodiment, the semi-circular shaped groove 20 comprises a first threaded opening 24 and a second threaded opening 26 defined there through. The first threaded opening 24 comprises a plurality of internal screw threads that are defined there through, and the second threaded opening 26 comprises a plurality of internal screw threads that are defined there through. The first threaded opening 24 and the second threaded opening 26 are each spaced apart from one another by a predetermined displacement for a rationale that will be explained in further detail below.

[0009] The semi-circular shaped portion 22 comprises a circular shaped through hole 28 and a kidney bean slot 30 that are defined there through. In an exemplary embodiment, the circular shaped through hole 28 is positioned symmetrically between the kidney bean slot 30. The circular shaped through hole 28 of the semi-circular shaped portion 22 is aligned with the second threaded opening 26 defined in the semi-circular shaped groove 20, and positioned against the semi-circular shaped groove 20. Consequently, the kidney bean slot 30 of the semi-circular shaped portion 22 is aligned with the first threaded opening 24 defined in the semi-circular shaped groove 20, and positioned against the semi-circular shaped groove 20.

[0010] After the circular shaped through hole 28 of the semi-circular shaped portion 22 is aligned with the second threaded opening 26 defined in the semi-circular shaped groove 20, and the kidney bean slot 30 of the semi-circular shaped portion 22 is aligned with the first threaded opening 24 defined in the semi-circular shaped groove 20, a first threaded screw 32 is inserted through the circular shaped through hole 28 and screwed onto the second threaded opening 26. The first threaded screw 32 that is inserted through the circular shaped through hole 28 and screwed onto the second threaded opening 26 extends partially through the plunger 14 of the high pressure fuel pump 10 until the first threaded screw 32 fastens the semi-circular shaped portion 22 within the semi-circular shaped groove 20. In an exemplary embodiment, a second threaded screw 34 is inserted through the kidney bean slot 30, and screwed onto the first threaded opening 24. The second threaded screw 34 that is inserted through the kidney bean slot 30 and screwed onto the first threaded opening 24 extends partially through the plunger 14 of the high pressure fuel pump 10 until the second threaded screw 34 fastens the semi-circular shaped portion 22 within the semi-circular shaped groove 20.

[0011] In an exemplary embodiment, the semi-circular shaped portion 22 is adapted to be rotated by a user. The rotation of the semi-circular shaped portion 22 by the user facilitates guiding the second threaded screw 34 within the kidney bean slot 30 to a user required displacement. At the user required displacement, a bottom edge 35 of the semi-circular shaped portion 22 is set at a user required angle, thereby setting the travel of the plunger 14 at which the rectangular shaped groove 18 comes in flow communication with a fuel inlet port (not shown) that is defined in the barrel of the high pressure fuel pump 10. At lower angles of the semi-circular shaped portion 22 with reference to the horizontal axis, the travel of the plunger 14 at which the rectangular shaped groove 18 comes in flow communication with the fuel inlet port that is defined in the barrel of the high pressure fuel pump 10 is reduced. Therefore, for a lower stroke length of the plunger 14, the fuel from the pumping chamber flows into the fuel inlet port via the rectangular shaped groove 18. Consequently, at lower angles of the semi-circular shaped portion 22 with reference to the horizontal axis, a lower quantity of fuel is pressurized and delivered from the pumping chamber of the high pressure fuel pump 10 before the rectangular shaped groove 18 comes in flow communication with the fuel inlet port that is defined in the barrel of the high pressure fuel pump 10. Once the fuel inlet port that is defined in the barrel of the high pressure fuel pump 10 comes in flow communication with the bottom edge 35 of the semi-circular shaped portion 22, the fuel from the pumping chamber flows into the fuel gallery via the vertical groove 16 and via the fuel inlet port. Consequently, no more fuel is pressurized and delivered from the pumping chamber to the fuel injector, as the plunger 14 continues translating towards its top dead center position.

[0012] At greater angles of the semi-circular shaped portion 22 with reference to the horizontal axis, the travel of the plunger 14 at which the rectangular shaped groove 18 comes in flow communication with the fuel inlet port that is defined in the barrel of the high pressure fuel pump 10 is correspondingly increased. Therefore, for a greater stroke length of the plunger 14, the fuel from the pumping chamber flows into the fuel inlet port via the rectangular shaped groove 18. Consequently, at greater angles of the semi-circular shaped portion 22 with reference to the horizontal axis, a greater quantity of pressurized fuel is delivered from the pumping chamber of the high pressure fuel pump 10 before the rectangular shaped groove 18 comes in flow communication with the fuel inlet port that is defined in the barrel of the high pressure fuel pump 10. Once the fuel inlet port that is defined in the barrel of the high pressure fuel pump 10 comes in flow communication with the bottom edge 35 of the semi-circular shaped portion 22, the fuel from the pumping chamber flows into the fuel gallery via the vertical groove 16 and via the fuel inlet port. Consequently, no more fuel is pressurized and delivered from the pumping chamber to the fuel injector, as the plunger 14 continues translating towards its top dead center position. Therefore, by varying the angle of the bottom edge 35 of the semi-circular shaped portion 22 with reference to the horizontal axis, the stroke length of the plunger 14 at which the fuel inlet port becomes aligned with the bottom edge 35 of the semi-circular shaped portion 22 may be correspondingly varied.

[0013] In an exemplary embodiment, the first threaded screw 32 and the second threaded screw 34 are flush against an outer surface of the plunger 14. As the first threaded screw 32 and the second threaded screw 34 are each flush against the outer surface of the plunger 14, the first threaded screw 32 and the second threaded screw 34 are prevented from coming in contact with a barrel of the high pressure fuel pump 10 during the reciprocation of the plunger 14 within the barrel. As the first threaded screw 32 and the second threaded screw 34 are flush against the outer surface of the plunger 14, a head of the first threaded screw 32 and the second threaded screw 34 are prevented from coming in contact with an inner surface of the barrel, thereby preventing abrasion with the inner surface of the barrel of the high pressure fuel pump 10.

[0014] 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 dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the scope of the claims.