Claims:We Claim

1. A high pressure fuel pump, said high pressure fuel pump comprising:
a housing;
a barrel positioned within said housing;
a groove defined within said barrel, said groove adapted to retain an O-ring therein, and wherein said O-ring is adapted to seal said barrel against said housing; characterized in that
a projection defined in said barrel that is defined between the groove that is defined within said barrel and a cylinder head of said barrel, the projection positioned against a chamfered portion that is defined in said housing to facilitate sealing said barrel against said housing.

2. The high pressure fuel pump in accordance with Claim 1 wherein said projection is a convex shaped portion that is integrally formed with said barrel, and which is positioned against the chamfered portion that is defined in said housing to facilitate sealing said projection of said barrel against said housing.

3. The high pressure fuel pump in accordance with Claim 2 wherein the convex shaped portion is formed between a shaft portion of said barrel and a flanged portion of said barrel and is positioned against the chamfered portion that is defined in said housing to facilitate sealing said projection of said barrel against said housing.
, 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 secondary seal defined in a barrel of a high pressure fuel pump.

Background of the invention
[0002] US Patent Publication Number 3669576 A describes a mechanically driven fuel priming pump for an internal combustion engine that comprises a one-piece housing having a barrel terminating at its lower end in a flange disposed transversely to the barrel. A plunger is reciprocally mounted in a chamber of the barrel to selectively pump fuel from a first to a second valve located in the flange of the housing. The barrel has an annular groove formed there around which seats an annular ring of low friction material therein. An O-ring seal is also disposed in the groove to urge the annular ring into intimate contact with wall portions defining the chamber.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a schematic diagram of 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 high pressure fuel pump 10 in one embodiment of the invention. The high pressure fuel pump 10 comprises a housing 12 and a barrel 14 positioned within the housing 12. A groove 16 is defined within the barrel 14, the groove 16 adapted to retain an O-ring 18 therein, and wherein the O-ring 18 is adapted to seal the barrel 14 against the housing 12. A projection 20 is defined in the barrel 14 that is defined between the groove 16 that is defined within the barrel 14 and a cylinder head of the barrel 14, the projection 20 positioned against a chamfered portion 22 that is defined in the housing 12 to facilitate sealing the barrel 14 against the housing 12.
[0005] The high pressure fuel pump 10 comprises a housing 12 that is adapted to house a barrel 14 therein. More specifically, the barrel 14 is positioned within the housing 12. In the exemplary embodiment, the barrel 14 comprises a groove 16 that is defined therein, wherein the groove 16 that is defined within the barrel 14 is a U-shaped groove. The groove 16 is adapted to retain an O-ring 18 therein, wherein the O-ring 18 is adapted to seal the barrel 14 against the housing 12. The O-ring 18 serves as a primary sealing arrangement between the barrel 14 and the housing 12, and prevents the fuel that is flowing into the barrel 14 from flowing out of the high pressure fuel pump 10 via the space between the barrel 14 and the housing 12. In the event that the O-ring 18 ruptures, the space between the ruptured O-ring 18 and the housing 12 is filled with the fuel that eventually flows out of the groove 16 thereby exiting the housing 12 of the high pressure fuel pump 10. To prevent the fuel from exiting the housing 12 of the high pressure fuel pump 10 from the groove, a secondary sealing arrangement is required, and is therefore provided.

[0006] A projection 20 is defined in the barrel 14 that is between the groove 16 that is defined within the barrel 14 and a cylinder head of the barrel 14. The projection 20 that is defined between the groove 16 that is defined within the barrel 14 and the cylinder head of the barrel 14 facilitates sealing the space between the housing 12 and the barrel 14 in addition to the O-ring 18. The projection 20 is a convex shaped portion that is integrally formed with the barrel 14, and which is positioned against the chamfered portion 22 that is defined in the housing 12 to facilitate sealing the projection 20 of the barrel 14 against the housing 12. In an exemplary embodiment, the projection 20 may be secured to the barrel 14 by attaching the projection 20 to the barrel 14 by means of an adhesive. In an alternate exemplary embodiment, the projection 20 may be secured to the barrel 14 during the forging process of the barrel 14.

[0007] The convex shaped portion 20 is formed between a shaft portion of the barrel 14 and a flanged portion of the barrel 14 and is positioned against the chamfered portion 22 that is defined in the housing 12 to facilitate sealing the projection 20 of the barrel 14 against the housing 12. More specifically, the convex shaped portion of the projection 20 extends from between the shaft portion of the barrel 14 and the flanged portion of the barrel 14, and abuts against the chamfered portion 22 that is defined in the housing 12. Due to the abutment of the convex shaped portion of the projection 20 against the chamfered portion 22 that is defined in the housing 12, a sealing contact is established between the barrel 14 and the housing 12. Therefore when the O-ring 18 ruptures, the fuel that escapes through the space between the O-ring 18 and the housing 12 is trapped within the groove within which the O-ring 18 is positioned and does not escape out of the high pressure fuel pump 10 through the space between the housing 12 and the barrel 14 due to the secondary sealing of the projection 20 between the barrel 14 and the housing 12.

[0008] A working of the secondary seal in the barrel 14 of the high pressure fuel pump 10 is described as an example. Fuel in the gallery of the high pressure fuel pump 10 is arrested from leaking out of the high pressure fuel pump 10 due to the O-ring 18 that is positioned within the groove 16 of the barrel 14. Therefore, the fuel is retained within the groove 16 of the barrel 14. In the event that the O-ring ruptures, the fuel from the gallery of the high pressure fuel pump enters and floods the groove of the barrel and tries to escape out of the housing of the high pressure fuel pump via the gap between the housing and the barrel. However, the convex shaped portion of the projection that extends from between the shaft portion of the barrel and the flanged portion of the barrel abuts against the housing of the high pressure fuel pump thereby sealing the gap that exists between the barrel and the housing and preventing the fuel that exists in the groove from escaping out of the high pressure fuel pump. Therefore, as the convex shaped portion of the projection that extends from between the shaft portion of the barrel and the flanged portion of the barrel abuts against the housing of the high pressure fuel pump, a secondary sealing mechanism is created between the barrel and the housing that prevents the fuel that exists in the groove from escaping out of the high pressure fuel pump.

[0009] 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.