Internal-combustion engines – Poppet valve operating mechanism – Rocker
Patent
1998-05-22
2000-05-16
Lo, Weilun
Internal-combustion engines
Poppet valve operating mechanism
Rocker
123 9042, 123 9039, 74569, 74559, F01L 118
Patent
active
060621842
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns a rocker arm or finger lever formed by a chipless or non-cutting shaping process from a sheet element which is formed over almost over its entire length into a U-shaped profile which is open toward the top or bottom whereby the rocker arm or finger lever is constructed double-walled in its end area in which it lies against a valve shaft end. Moreover, the invention concerns a further rocker arm or finger lever which, however, does not have a doubled seating surface in the valve-side region.
One such similar formed rocker arm or lever is previously known from U.S. Pat. No. 4,430,783. The double-sided seating surface in the valve-side area is realized in that a second metal strip adapted to the contours of the lever is installed on top of the entire length and joined with the U-shaped body which is open toward the bottom. Here there is the disadvantage that this lever is formed from two parts which must first be assembled together into a unit. A further disadvantage can be seen in that the lever must be constructed very massively and is consequently heavy, that is, it appears to have high inertia forces. A further disadvantage derives from the fact that such a lever possesses a very high side wall alongside the valve bearing surface. Accordingly, a high projecting length of the valve end to the valve spring retainer is also disadvantageous. That is, the overall height of the cylinder head increases, and the valve guide is subjected to greater stress owing to the length of the valve shaft.
Another rocker arm or lever is previously known from DE 41 33 033 A1. The lever shown in FIGS. 3 to 6 has lateral seating surfaces for the valve shaft which arise through a doubled wrapping or folding of the sheet. Due to this type of construction of the lever, however, a larger overall width is brought about disadvantageously. In addition, an increased use of materials goes along which the enlarged overall width, which brings about a larger mass and consequently a greater moment of inertia for the lever.
SUMMARY OF THE INVENTION
The object of the invention is therefore to develop a rocker arm or finger lever which guarantees a low weight and a small breadth with sufficient stability. A further object of the invention is to design such an arm or lever so that it is simple, and can consequently be manufactured economically.
This objective is accomplished in accordance with the invention through the features mentioned.
In one embodiment, a double-walled section is formed by at least one strap of an upper wall projecting beyond the longitudinal extension of the rocker arm or finger lever, which is bent thereunder and between the two side walls. After the bending process is completed, the bent strap lies between the two side walls and under the upper wall. On the basis of this construction of the lever in the valve-side area, the latter receives a particular stability, while at the same time, in comparison with the previous state of the art, a basic saving in weight is realized because the doubled construction of the bearing surface takes place only in the valve-side area. A further advantage can be seen in that, by bending the strap between the two side walls, the projection between the valve and the valve spring retainer, that is, the overall space, is diminished. Finally, such a lever configured according to the invention is functionally easy to manufacture, because it does not create any problems during the manufacturing process to allow the strap which is subsequently to be bent over or under to remain.
In accordance with a further configuration, the protruding strap is bent 180.degree. parallel to the upper wall, to lie on it, or leaving an intervening free space.
It is provided in a further configuration of the invention that the bent strap is joined fast with the upper wall, for example by welding or soldering. An especially high stability of the lever is reached through this fixed connection.
The strap or straps can be bent in different ways. Thus the strap can be
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Engelhardt Helmut
Mayer Wolfgang
Ina Walzlager Schaeffler OHG
Lo Weilun
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