| 摘要 |
<p>Herein is described an internal combustion engine of the four-stroke type, comprising a block within which one or more cylinders are obtained which respectively house one or more pistons which are mobile with an alternating motion. The block is surmounted by a single head for each cylinder, within which one or more intake ports are obtained for the fuel incoming into the respective cylinders and one or more exhaust ports for exhausting the combustion gases. The opening and closing of the intake and exhaust ports are controlled by respective intake and exhaust valves actuated by at least one camshaft. The camshaft is arranged in the block and its rotating movement is transformed into the alternating rectilinear motion of each valve by means of a corresponding hydraulic tappet. On each single head a single cover for each cylinder is permanently constrained, internally provided with at least two shaped seats capable of completely housing two respective rocker arms during the relative rotating movement around their own pins. In each shaped seat a corresponding circular hole is obtained, wherein the pin for rotating the rocker arm is fixed housed in such shaped seat. On the upper surface of the head one or more centring means are provided, which facilitate the mounting of the cover on the head, ensuring the correct coupling between the spherical head of each rod and a corresponding concave portion obtained in the rocker arm.</p> |
