Claims:We Claim

1. A shaft sealing ring (10) for a high pressure fuel pump, said shaft sealing ring (10) comprising:
a first portion (12) and a second portion (14) that are secured together to form an integral assembly;
a first lip (16) defined at a base of said first portion (12), and a second lip (18) defined at a base of said second portion (14), said first lip (16) and said second lip (18) each adapted to abut against a pump shaft (20) to prevent lubrication oil flowing on said pump shaft (20) from entering into said high pressure fuel pump via a space (22) defined between said first lip (16) and said second lip (18).

2. The shaft sealing ring (10) for a high pressure fuel pump in accordance with Claim 1 further comprising a breathing hole (24) defined between said first portion (12) and said second portion (14), the breathing hole (24) adapted to vent atmospheric air to the space (22) defined between said first portion (12) and said second portion (14).

3. The shaft sealing ring (10) for a high pressure fuel pump in accordance with Claim 2 wherein the breathing hole (24) is axially defined between said first portion (12) and said second portion (14).

4. The shaft sealing ring (10) for a high pressure fuel pump in accordance with Claim 1 further comprising a first metal plate (26) positioned within said first portion (12) and a second metal plate (28) positioned within said second portion (14), said first metal plate (26) and said second metal plate (28) each adapted to provide structural rigidity to said first portion (12) and said second portion (14) of said shaft sealing ring (10).

5. The shaft sealing ring (10) in accordance with Claim 1 further comprising positioning a first spring element (30) within a first groove defined within said first portion (12), and positioning a second spring element (34) within a second groove (36) defined within said second portion (14), said first spring element (30) adapted to provide a tensile force to abut said first lip (16) against said pump shaft (20), said second spring element (34) adapted to provide a tensile force to abut said second lip (18) against said pump shaft (20)
, 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 shaft sealing ring, and more specifically to a shaft sealing ring for a high pressure fuel pump.

Background of the invention
[0002] GB 1219569 A describes improvements in sealing rings. A shaft sealing ring comprises an elastomeric sealing lip formed with a series of studs which entered around the periphery of the ring adjacent the lip sealing area and, in use, create a pumping action tending to return fluid leaking past the lip sealing area. In the embodiment shown, the lip is urged against a rotatable shaft (not shown) by a garter spring and prevents leakage of oil from a first side to an opposite second side of the ring. Figs. 1 and 2 show the ring in its initial unworn condition and Figs. 4 and 5 show the ring when worn. In the unworn state, the lip has a sealing edge and the studs are inoperative. After a period of use, the edge and the studs are worn down to provide a cylindrical sealing area as in Figs. 4 and 5, each stud forming a dovetail extension of the area having curved surfaces and which act, according to the direction of shaft rotation, to return any oil droplets leaking past the area, to the side of the ring. In a modification, Figs. 7-12 (not shown), the studs are spaced apart from one another. In another modification, Figs. 16-18 (not shown), the end faces of the studs are conical.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a schematic diagram of a shaft sealing ring for a high pressure fuel pump in one embodiment of the invention.

Detailed description of the embodiments
[0004] Figure 1 illustrates a schematic diagram of a shaft sealing ring 10 for a high pressure fuel pump. The shaft sealing ring 10 comprises a first portion 12 and a second portion 14 that are secured together to form an integral assembly. A first lip 16 is defined at a base of the first portion 12, and a second lip 18 defined at a base of the second portion 14, the first lip 16 and the second lip 18 each adapted to abut against a pump shaft 20 to prevent lubrication oil flowing on the pump shaft 20 from entering into the high pressure fuel pump via a space 22 defined between the first lip 16 and the second lip 18.

[0005] The shaft sealing ring 10 for the high pressure fuel pump comprises a first portion 12 and a second portion 14. In the exemplary embodiment, the first portion 12 and the second portion 14 are secured together circumferentially to form an integral assembly about its axis. The first portion 12 and the second portion 14 of the shaft sealing ring 10 are each manufactured from a polytetrafluoroethylene (PTFE) based material. A first lip 16 is defined at a base of the first portion 12. The first lip 16 is adapted to abut against a pump shaft 20 that is rotating, and prevents the lubrication oil from flowing past the first lip 16 and the pump shaft 20, and entering the high pressure fuel pump. A second lip 18 is defined at a base of the second portion 14. The second lip 18 is adapted to abut against the pump shaft 20 that is rotating and prevents the fuel from the high pressure fuel pump from flowing past the interface of the second lip 18 and the pump shaft 20, and thereby escaping out of the high pressure fuel pump.

[0006] Therefore, the first lip 16 prevents lubrication oil that is flowing on the pump shaft 20 from entering into the high pressure fuel pump via the space 22 that is defined between the first lip 16 and the second lip 18. The second lip 18 prevents the fuel that is present in the space 22 that is defined between the first lip 16 and the second lip 18 from escaping from the space 22 that is defined between the first lip 16 and the second lip 18 and out of the high pressure fuel pump via the interface between the second lip 18 and the pump shaft 20.

[0007] The shaft sealing ring 10 for the high pressure fuel pump further comprises a breathing hole 24 that is axially defined between the first portion 12 and the second portion 14. More specifically, the breathing hole 24 is axially defined between the first portion 12 and the second portion 14 such that the first portion 12 and the second portion 14 are symmetrical about the breathing hole 24. When the pump shaft 20 rotates, a vacuum is created between the first lip 16 and the second lip 18 as the air between the first lip 16 and the second lip 18 gets squeezed out of the high pressure fuel pump. Due to the breathing hole 24 that is defined between the first portion 12 and the second portion 14, atmospheric air fills the space between the first lip 16 and the second lip 18 to ensure that vacuum does not build up in the space defined between the first portion 12 and the second portion 14, as the creation of vacuum between the first portion 12 and the second portion 14 misaligns the contact between the first lip 16 and the second lip 18 with the pump shaft 20. In the exemplary embodiment, the breathing hole 24 is axially defined between the first portion 12 and the second portion 14 of the shaft sealing ring 10.

[0008] The shaft sealing ring 10 comprises a first metal plate 38 that is positioned within the first portion 12. In addition, a second metal plate 40 is positioned within the second portion 14. The first metal plate 38 and the second metal plate 40 are each manufactured from a Z-shaped member and are integrally formed within the first portion 12 and the second portion 14 respectively. In the exemplary embodiment, the first metal plate 38 and the second metal plate 40 are each adapted to provide structural rigidity to the first portion 12 and the second portion 14 of the shaft sealing ring 10 respectively. In the absence of the first metal plate 38 and the second metal plate 40, the shaft sealing ring 10 would be a flexible member, and therefore would be incapable of performing the function of sealing the gap between the first portion 12, the second portion 14, and the pump shaft 20.

[0009] In the exemplary embodiment, the shaft sealing ring 10 comprises positioning a first spring element 30 within a first groove 32 that is defined within the first portion 12, and positioning a second spring element 34 within a second groove 36 that is defined within the second portion 14. The first spring element 30 and the second spring element 34 are each adapted to induce a tensile force on the first lip portion 16 and the second lip portion 18 such that the first lip portion 16 abuts against the pump shaft 20 and the second lip portion 18 abuts against the pump shaft 20, and prevents misalignment between the first lip 16, the second lip 18, and the pump shaft 20.

[0010] A working of the shaft sealing ring 10 is described as an example. The pump shaft 20 that is secured to a crank shaft of the engine rotates due to the rotation of the crank shaft. Due to the rotation of the pump shaft 20, the first lip 16 and the second lip 18 of the shaft sealing ring 10 gradually wear out over a period of time. When the first lip 16 of the shaft sealing ring 10 wears out, the lubrication oil that flows on the pump shaft 20 flows past the first lip 16 of the shaft sealing ring 10 and enters into the space 22 that is defined between the first lip 16 and the second lip 18 of the shaft sealing ring 10. Due to the contact of the second lip 18 with the pump shaft 20, the lubrication oil that is present in the space 22 between the first lip 16 and the second lip 18 cannot flow past the second lip 18 and into the barrel of the high pressure fuel pump where it may mix with the fuel in the barrel of the high pressure fuel pump.

[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.