Claims:We Claim

1. A high pressure fuel pump (10), said high pressure fuel pump (10) comprising:
a housing (12);
an element (14) positioned within said housing (12), said element (14) adapted to reciprocate within said housing (12);
a vertical groove (16) defined in said element (14), the vertical groove (16) adapted to extend along a sidewall of said element (14); characterized in that
a helix groove (18) in flow communication with the vertical groove (16) and extending angularly along a sidewall of said element (14), the helix groove (18) comprising an upper edge (20) having a first angle with reference to a horizontal axis, a lower edge (22) having a second angle with reference to the horizontal axis, and a connecting edge (24) that connects the upper edge (20) and the lower edge (22), wherein the first angle between the upper edge (20) and the horizontal axis is greater than the second angle between the lower edge (22) and the horizontal axis.

2. The high pressure fuel pump (10) in accordance with Claim 1, wherein the helix groove (18) in flow communication with the vertical groove (16) and extending angularly along the sidewall of said element (14) is aligned with reference to the horizontal axis such that the lower edge (22) extends along the horizontal axis of said high pressure fuel pump (10).

3. The high pressure fuel pump (10) in accordance with Claim 2, wherein the width of the helix groove (18) is sized such that when said element (14) reaches its top dead center position, a fuel inlet port (26) that extends through a barrel of said high pressure fuel pump (10) is in flow communication with the helix groove (18) to enable discharging pressurized fuel from a pumping chamber (28) to a fuel gallery of said high pressure fuel pump (10) via the fuel inlet port (26), thereby preventing secondary fuel injection from the pumping chamber (28) of said high pressure fuel pump (10) to a fuel injector that is in flow communication with the pumping chamber (28) 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 tapered / flattened helix groove to prevent secondary fuel injection from a high pressure fuel pump.

Background of the invention
[0002] IN 201941039450 A describes a fuel pump and an element for the same. The fuel pump comprises a barrel with an inlet port. An element with a vertical groove extends from a head of the element and in communication with a helix groove. The element is operable in a reciprocal manner. The vertical groove in combination with the head is used to block the inlet port at the start of fuel injection and helix groove to unblock the inlet port at end of the fuel injection. The element comprises a first groove and a second groove provided at the head, characterized by, the first groove and the second groove are made of equal width and positioned one below other. The second groove is away from the head of the element. The first groove and the second groove are step grooves.

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 an element with a tapered helix groove defined on the element of the high pressure fuel pump in one embodiment of the invention.
[0005] Figure 3 illustrates an element with a flattened helix groove defined on the element of the high pressure fuel pump in another embodiment of the invention.

Detailed description of the embodiments
[0006] A high pressure fuel pump 10 is described. The high pressure fuel pump 10 comprises a housing 12. An element 14 is positioned within the housing 12, the element 14 adapted to reciprocate within the housing 12. A vertical groove 16 is defined in the element 14, the vertical groove 16 adapted to extend along a sidewall of the element 14. A helix groove 18 is in flow communication with the vertical groove 16, and extends angularly along a sidewall of the element 14. The helix groove 18 comprises an upper edge 20 having a first angle with reference to a horizontal axis and a lower edge 22 having a second angle with reference to the horizontal axis. A connecting edge 24 connects the upper edge 20 and the lower edge 22. The connecting edge 24 connects the upper edge 20 and the lower edge 22, wherein the first angle between the upper edge 20 and the horizontal axis is greater than the second angle between the lower edge 22 and the horizontal axis.

[0007] 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. An element 14 is positioned within the housing 12, wherein the element 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 element 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 element 14, wherein the vertical groove 16 is adapted to extend along a sidewall of the element 14. The vertical groove 16 is adapted to channel pressurized fuel from the pumping chamber of the high pressure fuel pump 10 to a helix groove 18 that is in flow communication with the vertical groove 16. From the helix 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 26 that is defined in the barrel0.

[0008] Figure 2 illustrates an element 14 with a tapered helix groove 18 defined in the element 14 of the high pressure fuel pump 10 in one embodiment of the invention. The helix groove 18 is defined in the element 14 of the high pressure fuel pump 10. The helix groove 18 is in flow communication with the vertical groove 16, and extends angularly along a sidewall of the element 14. When the element 14 reciprocates within the housing 12 of the high pressure fuel pump 10, the element 14 is rotated by means of the governor of the high pressure fuel pump 10. As the element 14 translates towards the top dead center position, the helix groove 18 comes in flow communication with the fuel gallery of the high pressure fuel pump 10. Therein, the fuel from the pumping chamber 28 of the high pressure fuel pump 10 flows through the helix groove 18 via the vertical groove 16, and is finally discharged to the fuel gallery via the fuel inlet port 26. In an exemplary embodiment, the helix groove 18 extends downwardly towards a bottom portion of the element 14. More specifically, the helix groove 18 extends downwardly towards the bottom portion of the element 14 from the vertical groove 16 at one end to an opposite second end of the helix groove 18 at its opposite second end.

[0009] In an exemplary embodiment, the height of origination of the helix groove 18 from the top of the element 14 is minimum adjoining the vertical groove 16. Conversely, the height of termination of the helix groove 18 from the top of the element 14 is maximum at the opposite farthest end of the helix groove 18. Therefore, between the point of origination of the helix groove 18 and the point of termination of the helix groove 18, the helix groove 18 may have any user defined profile. Generally, the profile of the helix groove 18 between the point of origination of the helix groove 18 and the point of termination of the helix groove 18 is that of a linear profile. In an alternate exemplary embodiment, the profile of the helix groove 18 between the point of origination of the helix groove 18 and the point of termination of the helix groove 18 is that of a parabolic profile.

[0010] In an exemplary embodiment, the helix groove 18 that is in flow communication with the vertical groove 16 extends angularly along a sidewall of the element 14. The helix groove 18 comprises an upper edge 20 having a first angle with reference to a horizontal axis. In addition, the helix groove 18 comprises a lower edge 22 having a second angle with reference to the horizontal axis. A connecting edge 24 connects the upper edge 20 and the lower edge 22. More specifically, the first angle between the upper edge 20 and the horizontal axis is greater than the second angle between the lower edge 22 and the horizontal axis. Therefore, the helix groove 18 tapers from one end of the vertical groove 16 until it terminates at the opposite second end of the helix groove 18.

[0011] Figure 3 illustrates an element 14 with a flattened helix groove 30 defined in the element 14 of the high pressure fuel pump 10 in another embodiment of the invention. The flattened helix groove 30 that is in flow communication with the vertical groove 16 extends angularly along a sidewall of the element 14. The flattened helix groove 30 comprises an upper edge 20 having a first angle with reference to a horizontal axis. In addition, the flattened helix groove 30 comprises a lower edge 22 that extends angularly along a sidewall of the element 14 and is aligned with reference to the horizontal axis such that the lower edge 22 extends along the horizontal axis of the high pressure fuel pump 10. A connecting edge 24 connects the upper edge 20 and the lower edge 22. Therefore, the helix groove 18 tapers such that it originates from one end of the vertical groove 16 until it terminates at the opposite second end of the flattened helix groove 30.

[0012] In an exemplary embodiment, the width of the flattened helix groove 30 is sized such that when the element 14 reaches its top dead center position, a fuel inlet port 26 that extends through a barrel of the high pressure fuel pump 10 is in flow communication with the flattened helix groove 30. As the element 14 attains its top dead center position, the fuel inlet port 26 that is in flow communication with the fuel gallery of the high pressure fuel pump 10 at one end is in flow communication with the flattened helix groove 30 at its opposite second end. As the fuel inlet port 26 continues to remain in flow communication with the flattened helix groove 30 as the element 14 attains its top dead center position, pressurized fuel from the pumping chamber of the high pressure fuel pump 10 is discharged to the fuel gallery via the vertical groove 16, via the helix groove 18, and via the fuel inlet port 26. As all the fuel from the pumping chamber 28 of the high pressure fuel pump 10 is discharged to the fuel gallery via the vertical groove 16, via the helix groove 18, and via the fuel inlet port 26, secondary fuel injection is prevented from the pumping chamber 28 of the high pressure fuel pump 10 to a fuel injector that is in flow communication with the pumping chamber 28 of the high pressure fuel pump 10.

[0013] A working of the high pressure fuel pump 10 is now described as an example. The flattened helix groove 30 allows the flow of fuel from the pumping chamber 28 of the high-pressure fuel pump 10 to a low-pressure fuel gallery via the fuel inlet port 26 that is defined in the barrel of the high-pressure fuel pump 10. Therefore, as the load acting on the high-pressure fuel pump 10 is increased from a low load to a high load, the quantity of pressurized fuel that is delivered from the pumping chamber 28 of the high-pressure fuel pump 10 to a fuel injector increases in direct proportion to the stroke length of the element 14 from the top of the element 14 until the helix groove 18. More specifically, the quantity of pressurized fuel that is delivered from the pumping chamber 28 of the high-pressure fuel pump 10 to the fuel injector increases in direct proportion to the stroke length of the element 14 as the fuel inlet port 26 translates from the top portion of the element 14 until the fuel inlet port 26 becomes aligned with the flattened helix groove 30. In case of shallow pitch element, at the lower CRP region and at the maximum lift condition, the fuel inlet port 26 will be completely closed after the fuel inlet port 26 crosses the helix groove 18, which results in further pressurization of fuel thereby causing secondary fuel injection.

[0014] In the present invention, the flattened helix groove 30 comprises an upper edge 20 having the first angle with reference to the horizontal axis. In addition, the flattened helix groove 30 comprises the lower edge 22 having the second angle with reference to the horizontal axis, wherein the first angle between the upper edge 20 and the horizontal axis is greater than the second angle between the lower edge 22 and the horizontal axis. Alternatively, the lower edge 22 is aligned with reference to a horizontal axis of the high pressure fuel pump 10 in the second embodiment of the invention. As the width of the flattened helix groove 30 between the upper edge 20 and the lower edge 22 is sized such that when the element 14 reaches its top dead center position, the fuel inlet port 26 that extends through the barrel of the high pressure fuel pump 10 is in flow communication with the flattened helix groove 30. As the element 14 attains its top dead center position, the fuel inlet port 26 that is in flow communication with the fuel gallery of the high pressure fuel pump 10 at one end is in flow communication with the flattened helix groove 30 at its opposite second end. As the fuel inlet port 26 continues to remain in flow communication with the flattened helix groove 30 as the element 14 attains its top dead center position, pressurized fuel from the pumping chamber 28 of the high pressure fuel pump 10 is discharged to the fuel gallery via the vertical groove 16, via the flattened helix groove 30, and via the fuel inlet port 26. As all the fuel from the pumping chamber 28 of the high pressure fuel pump 10 is discharged to the fuel gallery via the vertical groove 16, via the flattened helix groove 30, and via the fuel inlet port 26, secondary fuel injection is prevented from the pumping chamber 28 of the high pressure fuel pump 10 to a fuel injector that is in flow communication with the pumping chamber 28 of the high pressure fuel pump 10.

[0015] 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.