The following documents are incorporated herein by reference as if fully set forth: German Patent Application No. 102015211124.5, filed Jun. 17, 2015.
The invention relates to a valve train of a reciprocating piston internal combustion engine with a transmission element in the form of a rocker arm or pivot arm that can be actuated, on one hand, at least indirectly by a cam of a camshaft and is in active connection, on the other hand, under intermediate connection of a valve bridge, with gas-exchange valves, wherein the valve bridge has at least one hydraulic valve lash compensation element, also called “HVA” below.
Such a valve train according to the class is known from DE 10 2010 011 454 A1. The document describes two constructions, wherein one construction has a bridge that is provided on one end with a hydraulic valve lash compensation element. Because this HVA can perform lash compensation for only one gas-exchange valve, the transmission element has, on its end, an adjusting screw with spherical cap so that the gas-exchange valve provided with an HVA must be adjusted and readjusted using the adjusting screw. In the second construction, the HVA is arranged in the middle of the valve bridge, wherein the connection to the transmission element is realized, in turn, by an adjusting screw and a spherical cap. Here it is not clear how differences in the length and extensions of the gas-exchange valves are to be set, because the HVA is active for both gas-exchange valves and must have an appropriately large volume construction.
The object of the invention is to provide a valve train, in which the previously described disadvantages are eliminated. The components of the valve train should have a simple, space-saving, and economical construction.
This objective is achieved in that, in the valve bridge, allocated to each gas-exchange valve, there is a hydraulic valve lash compensation element. In this way it is possible that the lash of each gas-exchange valve is readjusted individually and automatically and also the total adjustment is realized by the two valve lash compensation elements, so that an adjusting screw is not required. Through the allocation of one HVA to each gas-exchange valve, each hydraulic valve lash compensation element can be kept spatially small, in particular, it can have a narrow construction transverse to the valve bridge. This is especially important due to the limited installation space in four valve cylinder heads with central injectors. It is further proposed that, at the end of the transmission element, a spherical head tappet and a spherical cup are formed/installed, wherein the spherical cup contacts the valve bridge. A good pressurized medium supply is ensured in that, in the transmission element, starting from a pivot bearing supplied with pressurized medium, there is a pressurized medium line that connects to a pressurized medium hole in the spherical head tappet and to an opening in the spherical cup and that, in the valve bridge, starting from the spherical cup, there are pressurized medium channels that lead to the hydraulic valve lash compensation elements. To ensure that there is a passage for pressurized medium at all times between the spherical cup and the pressurized medium channels, it is provided that the pressurized medium channels are attached, in the valve bridge, facing the spherical cup, to an extension in the form of a cone or spherical section. In this way, shifts between the spherical cup and the bridge due to the tolerances are not critical.
The invention is described in the detailed description below which should be read in conjunction with the drawings, in which:
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Number | Date | Country | Kind |
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102015211124.5 | Jun 2015 | DE | national |