Internal-combustion engines – Poppet valve operating mechanism – Tappet
Reexamination Certificate
2001-06-12
2002-06-18
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Tappet
C074S569000
Reexamination Certificate
active
06405698
ABSTRACT:
The invention relates to a roller tappet as defined in the introductory part of claim
1
.
Such roller tappets are known, for example from U.S. Pat. No. 5,385,125 A. The axle of the roller is secured according to said patent via locking rings that are located within the bosses of the axle.
Said solution has a number of drawbacks: the supporting length of the roller axle is limited by the locking rings and the bearing is consequently subjected to higher stresses. Furthermore, cutting grooves in drilled holes requires substantial higher expenditure as compared to grooves located on the outside diameter.
The invention, therefore, is dealing with the problem of securing in conjunction with roller tappets of the type specified above the axle supporting the roller in a simple manner in the bosses of the hubs.
Said problem is solved in conjunction with roller tappets of the type specified above by the characterizing features of claim
1
. Advantageous advanced developments of the invention are the object of the dependent claims.
It is entirely possible in this connection that the basic body of the tappet comprises one or a plurality of components that are connected with one another.
In conjunction with the solution as defined by the invention, the flanks of the locking ring no longer act as the surfaces on which the axle of the roller is running up, but said function is rather assumed now by the areas of the locking ring that are disposed radially inwards.
By virtue of the way in which the axle of the roller is secured as defined by the invention, with the help of locking rings that are disposed in grooves produced on the outside diameter of the roller tappet, machining costs are saved and only one locking ring is required, though one with a larger size. Another advantage has to be seen in the fact that only one groove needs to be cut.
The locking ring as defined by the invention does not have to be located in a plane containing the longitudinal axis of the roller axle, viewed in the axial direction of the tappet, but it may be located above or below said plane as well. It suffices if the roller axle, when displaced in the roller boss, runs up against the locking ring from the inside. Due to the out-of-center position of the locking ring, it is possible to increase the length of the roller axle and thus the supporting length even more as well.
REFERENCES:
patent: 5385124 (1995-01-01), Hillenbrand et al.
patent: 36 18 240 (1987-12-01), None
patent: 42 25 363 (1994-02-01), None
patent: 195 27 720 (1997-02-01), None
Collard & Roe P.C.
Denion Thomas
Mahle Ventiltrieb GmbH
O'Brien Sean D.
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