Verfahren zur Anbringung einer keramischen Ventilführungsanordnung

摘要

In order to achieve great engine efficiency, heat, normally dissipated through the cooling system, is directed through the exhaust passage to increase the turbocharger speed. Ceramic valve guides capable of withstanding high temperature ranges are being used for increased engine efficiency. Unfortunately, the resultant interference fit achieved through conventional shrink fitting the ceramic valve guide into the cylinder head will be lost once the engine is at operating temperatures due to the differential thermal expansion between the ceramic and the cylinder head material. The present invention provides a simple means for ensuring that the ceramic valve guide will be mounted within a cylinder head in a way that ensures that the ceramic valve guide is held in place within the cylinder head throughout the operating cycles of the engine. This is accomplished by utilizing a securing assembly which circumferentially surrounds the ceramic valve guide. The securing assembly includes a lower and an upper securing element and a spring disposed between the lower and the upper securing element. When installed in the engine, a valve spring places an axial load on the securing element which compresses the spring and forces the lower and the upper securing element into radial engagement with the ceramic sleeve and the cylinder head. Thereby, forcibly connecting the ceramic valve guide and the cylinder head.