Internal-combustion engines – Poppet valve operating mechanism – Rocker
Patent
1998-09-04
2000-05-23
Argenbright, Tony M.
Internal-combustion engines
Poppet valve operating mechanism
Rocker
123 9043, 123 9055, F01L 120, F01L 118
Patent
active
060654341
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns a rocker arm or a finger lever comprising on an end thereof adjacent a valve stem end of a gas exchange valve, a reception bore in which is arranged a valve clearance compensation element, a hollow inner piston of the valve clearance compensation element being supported on a cap which delimits the reception bore at one end in axial direction, said inner piston, together with the cap, surrounding an oil reservoir which is connected to an oil supply bore through at least one aperture provided in the substantially disc-shaped cap.
BACKGROUND OF THE INVENTION
A rocker arm of the pre-cited type is known from DE-A 26 52 154. In this case, the cap is configured as a flat disc which is secured in axial direction in the reception bore by a circlip. The outer diameter of the disc and the diameter of the reception bore are matched to each other so that a narrow annular gap is formed therebetween through which air can escape to the exterior. Further, the hollow inner piston of the valve clearance compensation element is provided on its end with slots, or radially extending grooves are provided in the end face of the disc facing the inner piston. The two last-mentioned means are intended to permit the pressure medium which flows from the oil supply bore at first into an annular space to flow further into the oil reservoir. A drawback of this arrangement is that the cap can become displaced radially to the extent that a vent gap is formed only in a certain edge region. Depending on the position of this gap and the position the rocker arm or the finger lever takes during the standstill of the internal combustion piston engine, so much pressure medium can escape from the valve clearance compensation element through this vent gap that the operation of the valve clearance compensation element is not guaranteed at first on a re-starting of the internal combustion piston engine. In addition, the oil serving as the pressure medium can flow out through the guide gap between the valve clearance compensation element and the peripheral surface of the reception bore. Moreover, the fact that grooves have to be made in the disc, or slots stamped into the inner piston, increases the costs of manufacture.
SUMMARY OF THE INVENTION
The object of the invention is therefore to eliminate the mentioned drawbacks and create, in a simple manner, a cap which conveys the pressure medium into the oil reservoir and serves simultaneously to vent the same.
The invention achieves this object by the fact that, on the end of the cap turned away from the oil reservoir, there is arranged at least one extension which projects in axial direction and engages into a complementary opening of the rocker arm or the finger lever and, together with a wall section of the opening forms a vent orifice. This means that the cap is exactly guided in the opening so that a vent function and a conveyance of pressure medium into the oil reservoir can both be assured by simple means.
The extension can be configured as a concentric cylindrical formation while the opening is a bore extending concentrically to the reception bore. Such a formation can be made on the disc in a simple manner by chipless forming. The bore of the rocker arm or the finger lever is then provided with a stepped configuration which can be made by simple means, for example in a cast rocker arm or finger lever. It is, however, also possible to make the rocker arm or the finger lever out of sheet metal in which case, the reception bore can be consituted by a cylindrical sheet metal element. In addition, with the help of this formation, the volume of the oil reservoir can be enlarged without a modification of the overall height of the valve clearance compensation element. Consequently, if the volume of the oil reservoir is left unchanged, the overall height can be reduced.
According to a further development of the invention, the cap can be secured against rotation in the rocker arm or the finger lever by press-fitting the formation into the bore. Such a
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Argenbright Tony M.
Hairston Brian J.
Ina Walzlager Schaeffler OHG
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