Cam follower

#This application claims the priority of DE 10 2010 033 120.1 filed Aug. 3, 2010, which is incorporated by reference herein.

#The invention relates to a cam follower for a high-pressure fuel pump or for a valve drive in each case of an internal combustion engine with quantity or quality regulation, having a cam roller which is accommodated in a pocket of the cam follower, which cam roller is mounted by means of its bore on a pin which is seated at the ends in receptacles of opposite walls of the pocket, the cam roller running with its end sides directly in front of said walls.

#A cam follower of said type emerges from DE 10 2005 047 234 A1. Said cam follower is designed as a cup-shaped tappet and serves to exert a periodic loading on a pump piston of a fuel pump. A further cam follower is described in DE 103 54 683 A1. Said cam follower takes the form of a rocker arm and is used for exerting a loading on a gas exchange valve in a valve drive.

#The invention will be explained on the basis of the drawing, in which:

#FIGS. 1-4 show a cam follower for a high-pressure fuel pump, designed in this case as a roller tappet, in two side views and two sectional views;

#FIG. 5 shows a three-dimensional view of a cam follower for a valve drive, designed in this case as a rocker arm;

#FIGS. 1-4 show a cam follower 1, designed as a cup-shaped tappet, for a high-pressure fuel pump of an internal combustion engine. The cam follower 1 is composed of a hollow cylindrical skirt 14, from the drive-side edge 13 of which extends a pocket 2. A cam roller 3 is accommodated in said pocket. Said cam roller has a bore 4 with a rolling bearing 12 by means of which the cam roller 3 runs on a pin 5. The pin 5 is seated at the ends in receptacles 6 of opposite walls 7 of the pocket 2. The walls 7 are formed as diametrically opposite recessed longitudinal flattened portions 18. The cam roller 3 runs with its end sides 8 directly in front of and/or against the walls 7.

#As can be most clearly seen in this context from FIG. 6, each end side 8 of the cam roller 3 is formed as an outer surface of a spherical zone. In other words, said end side 8 is of crowned or domed design. At the same time, each wall 7 has a smooth-walled, plain profile in the region of its run-on piece 11, i.e., the portion of the wall 7 on which the cam roller 3 can run. A section 10, which directly adjoins an annular edge 9 in the bore 4, of the respective end side 8 of the cam roller 3 is, however, of planar design.

#If the cam roller 3 runs “obliquely” with one of its end sides 8 against the opposite wall 7, then the contact region in the edge section of the end side 8 to the outer casing 17 is made much “less severe”. The wear problems described in the introduction are no longer to be expected. At the same time, a sharp-edged transition region of the end side 8 to the bore 4 is avoided as a result of the fact that the end side 8 is initially of planar form radially at the inside.