| 摘要 |
A valve train assembly 5 for an engine 1 comprising a rotatable camshaft 7 having a cam arrangement 11 axially movable along the camshaft so that the assembly is selectively configurable in a first configuration (figure 3) wherein a valve 9 is operated by the cam arrangement as the camshaft rotates to provide a corresponding valve event in each of a plurality of successive cylinder cycles, and a second configuration (figure 4) wherein the valve is operated to provide a corresponding valve event in every other cylinder cycle. Preferably the camshaft is arranged to rotate at one quarter of the speed of the crankshaft of the engine and the cam arrangement comprises first and second cams 15, 17, the first cam comprising first and second lift lobes 15b. The assembly can be used in an engine with an odd number of cylinders and when operated in a particular firing order, given that valve events are provided in alternate cylinder cycles, half of the cylinders are effectively deactivated. |
