Claims:We Claim
1. A roller tappet (10) for a high pressure fuel pump, said roller tappet (10) comprising:
a roller tappet body (12);
a roller (14) positioned within said roller tappet body (12);
a bearing bolt (16) positioned within said roller (14);
a retainer ring (18) wound around said bearing bolt (16) for securing said bearing bolt (16) to said roller tappet body (12); characterized in that
a chamfer (20) defined between an inner surface (22) of said roller (14) and a side surface (24) of said roller (14) and adjacent to said retainer ring (18), said chamfer (20) prevents said retainer ring (18) from contacting said roller (14).

2. The roller tappet (10) for a high pressure fuel pump in accordance with Claim 1, comprising another chamfer (21) defined between the inner surface (22) of said roller (14) and another side surface (25) of said roller (14) and opposite to said retainer ring (18), said chamfer (20) and said another chamfer (21) provide pathways to facilitate sufficient lubrication oil to the interfaces between the roller tappet body (12) and the side surface (24) of the roller (14), between the roller tappet body (10) and the another side surface (25) of the roller (14), and between the bearing bolt (16) and inner surface (22) of the roller (14).

3. The roller tappet (10) for a high pressure fuel pump in accordance with Claim 2 wherein said chamfer (20) and said another chamfer (21) is angled at about 45 degrees.
, Description:Field of the invention
[0001] This invention relates to a roller tappet and more particularly to a roller that is secured to a roller tappet body of the roller tappet.

Background of the invention
[0002] US 2006/288974 A describes a connection of a bearing bolt in a cylindrical housing of a roller tappet that is actuated in the direction of the longitudinal axis (Z), especially for a tappet push-rod valve drive of an internal combustion engine. The bearing bolt is supported in bore holes of the housing, which extend in a transverse plane (XY) to the roller tappet, perpendicular to the longitudinal axis (Z), and is connected with a positive and/or non-positive fit to the housing through material deformation. The material deformation is provided as one or more segments of which at least one segment completely encloses a radial load zone of the bearing bolt, and a section of the bearing bolt extending about the transverse plane (XY) is free from material deformation.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a schematic diagram of a roller tappet for a high pressure fuel pump.

Detailed description of the invention
[0004] Figure 1 illustrates a roller tappet 10 for a high pressure fuel pump. The roller tappet 10 comprises a roller tappet body 12 and a roller 14 positioned within the roller tappet body 12. A bearing bolt 16 is positioned within the roller 14. A retainer ring 18 is wound around the bearing bolt 16 for securing the bearing bolt 16 to the roller tappet body 12.
[0005] The roller 14 comprises an inner surface 22, a side surface 24, and another side surface 25. A chamfer 20 is defined between the inner surface 22 of the roller 14 and the side surface 24 of the roller 14, adjacent to the retainer ring 18. Another chamfer 21, identical to chamfer 20, is symmetrically defined between the inner surface 22 of the roller 14 and the another side surface 25 of the roller 14 and opposite to the retainer ring 18.
[0006] In an exemplary embodiment, the chamfer 20 and the another chamfer 21 have an angle of 45 degrees with respect to the side surface 24 of the roller 14 and the another side surface 25 of the roller 14 respectively. The chamfer 20 prevents the roller 14 from contacting the retainer ring 18 during operation. The absence of contact between the roller 14 and the retainer ring 18 prevents wear caused by abrasion between the roller 14 and the retainer ring 18 that would otherwise have been caused in the absence of the chamfer 20.
[0007] In addition, the chamfer 20 and the another chamfer 21 also provide suitable pathways for lubrication of various interfaces in the roller tappet 10 thereby reducing wear at their interfaces. The chamfer 20 provides a path for sufficient lubrication between the roller tappet body 12 and the side surface 24 of the roller 14, whereas the another chamfer 21 provides a path for sufficient lubrication between the roller tappet body 12 and the another side surface 25 of the roller 14. Furthermore, the chamfer 20 and the another chamfer 21 also provide pathways to facilitate the lubrication of the interface between the inner surface 22 of the roller 14 and the bearing bolt 16.
[0008] In an alternative exemplary embodiment, the chamfer 20 and the another chamfer 21 have any suitable size or angle with respect to the side surface 24 and the another side surface 25 of the roller 14 that prevents the roller 14 from contacting the retainer ring 18 and facilitate sufficient lubrication to the interfaces between the roller tappet body 12 and the side surface 24 of roller 14, between the roller tappet body 12 and the another side surface 25 of the roller 14, and between the bearing bolt 16 and the inner surface 22 of the roller 14.
[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 leverage and dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the claims.