GB2286783A

GB2286783A - Non-chipping manufacturing method for a mechanical valve tappet

Info

Publication number: GB2286783A
Application number: GB9504009A
Authority: GB
Inventors: Dieter Schmidt; Michael Zipprath
Original assignee: INA Waelzlager Schaeffler OHG
Current assignee: INA Waelzlager Schaeffler OHG
Priority date: 1994-02-28
Filing date: 1995-02-28
Publication date: 1995-08-30
Anticipated expiration: 2015-02-28
Also published as: GB2286783B; DE4406407A1; GB9504009D0

Description

m& 2286783 1 Non-chipping manufacturing method for a mechanical valve

tal:)Det The invention concerns a method f or the non- chipping manufacture of a mechanical valve tappet which in use is arranged in a guide bore of a cylinder head of an internal combustion engine and comprises a cup-shaped housing having a hollow cylindrical wall closed at one end by a bottom which is contacted on the outside by a control cam while a flat end face of an adjusting element bears against the inner surface of the bottom and another end face of the adjusting element parallel thereto is in contact with the end of a valve stem of an intake or exhaust valve. The invention further concerns a valve tappet made by this method.

Methods for the non-chipping manufacture of mechanical valve tappets are known since a long time. However, it often happens that due to surface defects, e. g. in the strip material, by which are to be understood differing material thicknesses, waviness or bumps and depressions, the compensation element makes oblique contact and is therefore subjected to compression across the edges at the cup bottom or the valve stem. This in turn leads to an undesired increase in valve clearance. By reason of these shape variations of the strip material over the width of the valve tappet, it is also possible that a valve tappet thickness value is determined which does not correspond to the actual value at the contact surface of the adjusting element. This then leads to the installation of a wrongly sized adjusting element.

To avoid the occurrence of an undesired large valve clearance or the use of a wrongly sized adjusting element in valve tappets shaped without chip removal, it was hitherto necessary to subject the contact surface on the inner surface of the bottom to a machining c-peration such as polishing or fine turning.

The object of the invention is therefore to improve the nonchipping manufacture of mechanical valve tappets in such a way that a subsequent machining of the contact surf ace is no longer necessary.

2 The invention achieves this object in accordance with one aspect by the f act that a contact surf ace parallel to the outer surf ace of the cup bottom is made on the inner surface of the bottom by an additional upsetting or stamping operation during or after the shaping process.

By this material compaction in the region of the contact surface it is obtained that a markedly lower number of surf ace def ects such as differing material thickness, waviness or bumps and depressions are present so that a substantially improved parallelism exists between the outer surface of the cup bottom and the contact surface as compared with the parallelism between the entire inner surf ace of the bottom and the outer surf ace of the cup bottom. The hitherto necessary machining of the contact surface can be dispensed with because the adjusting element cannot make oblique contact, i. e. parallelism exists between the contact surface, the compensation element and the end face of the valve stem.

According to another aspect of the invention a contact surface which is convex with respect to the outer surface of the cup bottom is made on the inner surf ace of the bottom by an additional upsetting or stamping operation during or after the shaping process. This convex configuration permits a compensation of manufacturing tolerances of the cylinder head and valve drive components, that is to say, the non-even configuration of the contact surface in this case assures that parallelism exists between the compensation element and the end face of the valve shaft in spite of manufacturing tolerances.

A development of the invention, according to claim 3, provides that the contact surface on the inner surface of the bottom is configured as a depression or raised portion.

As can be seen from claim 4, in the case of a depression, the diameter of the contact surface should be slightly larger than the diameter of the adjusting element.

According to claim 5, in the case of a raised portion, the f 3 diameter of the contact surface can be larger or smaller than the diameter of the adjusting element, the diameter reduction being limited by a too large surface compression between the raised portion and the adjusting element.

For a further elucidation of the invention, reference is made to the drawings In which two examples of embodiment are represented in simplified form. In the drawings:

Fig. I is a longitudinal section through a mechanical cup tappet, the contact surface of which is configured as a depression, and Fig. 2 is a longitudinal section through a mechanical cup tappet, the contact surface of which is configured as a raising or upstand.

Pigs. 1 and 2 each show a mechanical cup tappet comprising a hollow cylindrical wall 1 and a bottom 2. In the installed state of the mechanical valve tappet, a control cam, not represented, of a camshaft of an internal combustion engine runs on this bottom 2. An end face 4 of an adjusting element 3, which is available in different axial dimensions, bears against an inner surf ace of the bottom 2 to adjust the valve clearance of the internal combustion engine. Another end face 5 of the adjusting element bears against an end of a valve stem of an intake or exhaust valve. For the sake of simplicity, however, the adjusting element 3 is represented without the intake or exhaust valve, and not in its end position.

In Fig. 1, the bottom 2 of the cup tappet is provided on its inner surface with a contact surface 6 which extends in a depression 7. The contact surf ace 6 of the depression 7 has a diameter 9 which is slightly larger than the diameter 10 of the adjusting element 3. As already described, a contact surface 6 parallel to the outer surface of the cup bottom is made on the inner surf ace of the bottom 2 by material compaction by an additional upsetting or stamping operation during or after the shaping process. This results in parallelism prevailing between 4 the contact surface 6, the end faces 4 and 5 of the adjusting element 3 and the parallel end face of the valve shaft of the intake and exhaust valve.

In Fig. 2, the contact surface 6 on the inner surface of the bottom 2 is configured as a raised portion 8 whose diameter 9 is smaller than the diameter 10 of the adjusting element 3. This raised portion 8 is likewise provided with a contact surface 6 parallel to the outer surface of the cup bottom by material compaction by an additional upsetting or stamping operation during or after the shaping process.

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Claims

Claims

A method for the non-chipping manufacture of a mechanical valve tappet which in use is arranged In a guide bore of a cylinder head of an internal combustion engine and comprises a cup-shaped housing having a hollow cylindrical wall (1) closed at one end by a bottom (2) which is contacted on the outside by a control cam while a flat end face (4) of an adjusting element (3) bears against the inner surface of the bottom (2) and another end face (5) of the adjusting element (3) parallel thereto is in contact with the end of a valve stem of an intake or exhaust valve, characterized in that a contact surface (6) parallel to the outer surface of the cup bottom is made on the inner surface of the bottom (2) by an additional upsetting or stamping operation during or after the shaping process.
2. A method for the non-chipping manufacture of a mechanical valve tappet which in use is arranged In a guide bore of a cylinder head of an internal combustion engine and comprises a cup-shaped housing having a hollow cylindrical wall (1) closed at one end by a bottom (2) which is contacted on the outside by a control cam while a flat end face (4) of an adjusting element (3) bears against the inner surface of the bottom (2) and another end face (5) of the adjusting element (3) parallel thereto is in contact with the end of a valve stem of an intake or exhaust valve, characterized in that a contact surface (6) which is convex with respect to the outer surface of the cup bottom is made on the inner surf ace of the bottom by an additional upsetting or stamping operation during or af ter the shaping process.
3. A valve tappet manufactured by a method according to claim 1 or 2, characterized in that the contact surface (6) on the inner surface of the bottom (2) is configured as a depression (7) or a raised portion (8).
4. A valve tappet manufactured by a method according to claim 1 or 2, characterized in that, in the case of the depression (7), a diameter (9) of the contact surface (6) is slightly 6 larger than a diameter (10) of the adjusting element (3).
5. A valve tappet manufactured by a method according to claim 1 or 2, characterized in that, in the case of the raised portion (8), the diameter (9) of the contact surface (6) is larger or smaller than the diameter (10) of the adjusting element (3).
6. A valve tappet substantially as described with reference to Fig. 1 or Fig. 2 of the drawings.

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