Claims:CLAIMS

We Claim

1. A high-pressure fuel pump (10), said high-pressure fuel pump (10) comprising:
a housing;
a barrel (12) positioned within said housing and secured thereto;
a plunger (14) positioned within a pumping chamber (16) that is defined within said barrel (12), said plunger (14) adapted to reciprocate within the pumping chamber (16) to facilitate delivering pressurized fuel from within the pumping chamber (16) to a fuel injector; characterized in that
at least one split ring (18) defined on an outer circumference of said plunger (14), said at least one split ring (18) adapted to prevent fuel from the pumping chamber (16) from flowing into an oil sump, and wherein said at least one split ring (18) is adapted to prevent lubrication oil from the oil sump from flowing into the pumping chamber (16).

2. The high-pressure fuel pump (10) in accordance with Claim 1, wherein said at least one split ring (18) comprises a first split ring (20), a second split ring (22), and a third split ring (24) that are spaced longitudinally apart from one another along a longitudinal axis of said high-pressure fuel pump (10), wherein said second split ring (22) prevents fuel that flows past said first split ring (20) from flowing past said second split ring (22) towards said third split ring (24).

3. The high-pressure fuel pump (10) in accordance with Claim 1, wherein said at least one split ring (18) comprises a first split ring (20), a second split ring (22), and a third split ring (24) that are spaced longitudinally apart from one another along a longitudinal axis of said high-pressure fuel pump (10), wherein said second split ring (22) prevents lubrication oil that flows past said third split ring (24) from flowing past said second split ring (22) towards said first split ring (20).

4. The high-pressure fuel pump (10) in accordance with Claim 1, wherein said at least one split ring (18) extends from a first end (26) along a body of said plunger (14) and partially around an outer circumference of said plunger (14), said at least one split ring (18) culminates at a second end (28) prior to the first end (26) of said at least one split ring (18).
, 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 at least one split ring defined on a plunger of the high-pressure fuel pump.

Background of the invention
[0002] GB 1001111 A describes a fuel injection pump. To prevent seizure of a plunger in the bore of a fuel injection pump, a ring having a coefficient of thermal expansion greater than the plunger is tightly fitted against the outer periphery of a groove surrounding the bore. The ring may be of aluminium, the plunger of hardened steel and the pump body of cast iron. The plunger is rotated by a drive shaft and is reciprocated by a cam which engages with roller as the plunger rotates.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a plunger comprising at least one split ring defined therein that is positioned within a barrel of a high-pressure fuel pump.

Detailed description of the embodiments
[0004] Figure 1 illustrates a high-pressure fuel pump 10. The high-pressure fuel pump 10 comprises a housing, and a barrel 12 positioned within the housing and secured thereto. A plunger 14 is positioned within a pumping chamber 16 that is defined within the barrel 12. The plunger 14 is adapted to reciprocate within the pumping chamber 16 to facilitate delivering pressurized fuel from within the pumping chamber 16 to a fuel injector. At least one split ring 18 is defined on an outer circumference of the plunger 14, the at least one split ring 18 adapted to prevent fuel from the pumping chamber 16 from flowing into an oil sump. The at least one split ring 18 is adapted to prevent lubrication oil from the oil sump from flowing into the pumping chamber 16.

[0005] Figure 1 illustrates a plunger 14 comprising at least one split ring 18 defined therein that is positioned within a barrel 12 of a high-pressure fuel pump 10. The high-pressure fuel pump 10 comprises a housing, within which the barrel 12 is positioned. More specifically, the barrel 12 is positioned within the housing of the high-pressure fuel pump 10 and secured thereto. In an exemplary embodiment, a plunger 14 is positioned within a pumping chamber 16 that is defined within the barrel 12 of the high-pressure fuel pump 10. The plunger 14 is adapted to reciprocate within the pumping chamber 16 of the high-pressure fuel pump 10 to facilitate delivering pressurized fuel from within the pumping chamber 16 to a fuel injector. From the fuel injector, the pressurized fuel is delivered to an engine cylinder and therein injected into the cylinder of the engine.

[0006] In an exemplary embodiment, at least one split ring 18 is defined on an outer circumference of the plunger 14. More specifically, at a particular position along the longitudinal length of the plunger 14, the at least one split ring 18 originates and therein extends along the outer circumference of the plunger 14. The at least one split ring 18 is adapted to prevent fuel from the pumping chamber 16 from flowing into an oil sump. Moreover, the at least one split ring 18 is adapted to prevent lubrication oil from the oil sump from flowing into the pumping chamber 16 against the force of gravity. The construction and working of the at least one split ring 18 is herein described in the following sections.

[0007] In an exemplary embodiment, the at least one split ring 18 comprises a first split ring 20, a second split ring 22, and a third split ring 24 that are spaced longitudinally apart from one another and extend along a longitudinal axis of the high-pressure fuel pump 10. In the exemplary embodiment, the second split ring 22 prevents fuel that flows past the first split ring 20 from flowing past the second split ring 22 towards the third split ring 24. Therefore, the fuel that flows from the pumping chamber 16 past the first split ring 20 is entrapped in the space between the first split ring 20 and the second split ring 22 and is therefore prevented from flowing past the third split ring 24 and into the oil sump of the high-pressure fuel pump 10.

[0008] In an exemplary embodiment, the at least one split ring 18 comprises a first split ring 20, a second split ring 22, and a third split ring 24 that are spaced longitudinally apart from one another. More specifically, the first split ring 20, the second split ring 22, and the third split ring 24 and positioned apart from one another and are spaced apart from one another along a longitudinal axis of the high-pressure fuel pump 10. The second split ring 22 that is spaced longitudinally from the third split ring 24 prevents lubrication oil from the oil sump that flows across the third split ring 24 from flowing across the second split ring 22 and towards the first split ring 20. Therefore, the second split ring 22 acts as a barrier to lubrication oil flow from the space between the second split ring 22 and the third split ring 24 to the space between the first split ring 20 and the second split ring 22.

[0009] In an exemplary embodiment, the at least one split ring 18 extends from a first end 26 along a body of the plunger and is wound partially around an outer circumference of the plunger 14. More specifically, the at least one split ring 18 that originates from a first end 26 along the body of the plunger 14 is wound partially around the outer circumference of the plunger 14 and culminates prior to the first end 26 of the at least one split ring 18. Therefore, a circumferential gap 30 exists between the first end 26 of the at least one split ring 18 and the opposite second end 28 of the at least one split ring 18.

[0010] A working of the at least one split ring 18 defined on a plunger 14 of a high-pressure fuel pump 10 is now described as an example. As fuel that is present within the pumping chamber 16 of the high-pressure fuel pump 10 flows between the clearance of the plunger 14 and the barrel 12 due to gravity, the pressurized fuel flows past the first split ring 20 and accumulates in the space between the first split ring 20 and the second split ring 22. The second split ring 22 prevents the pressurized fuel that is present in the gap between the first split ring 20 and the second split ring 22 from flowing past the second split ring 22 and accumulating in the gap between the second split ring 22 and the third split ring 24. As lubrication oil that is present within the oil sump of the high-pressure fuel pump 10 flows between the clearance of the plunger 14 and the barrel 12 during the translation of the plunger 14 from its bottom dead center position to its top dead center position, the pressurized lubrication oil flows past the third split ring 24 and accumulates in the space between the third split ring 24 and the second split ring 22. The second split ring 22 prevents the pressurized lubrication oil that is present in the gap between the third split ring 24 and the second split ring 22 from flowing past the second split ring 22 and accumulating in the gap between the first split ring 20 and the second split ring 22. Therefore, the first split ring 20, the second split ring 22, and the third split ring 24 that are defined on the plunger 14 of the high-pressure fuel pump 10 facilitates preventing the pressurized fuel from the pumping chamber 16 of the high-pressure fuel pump 10 from flowing into the oil sump past the first split ring 20, the second split ring 22, and the third split ring 24 respectively. Similarly, the first split ring 20, the second split ring 22, and the third split ring 24 that are defined on the plunger 14 of the high-pressure fuel pump 10 facilitates preventing the pressurized lubrication oil from the oil sump of the high-pressure fuel pump 10 from flowing into the pumping chamber 16 past the third split ring 24, the second split ring 22, and the first split ring 20 respectively. Therefore, the first split ring 20, the second split ring 22, and the third split ring 24 facilitate preventing mixing of fuel in lubrication oil and similarly preventing mixing of lubrication oil in fuel in the high-pressure fuel pump 10.

[0011] 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.