| 摘要 |
<p>An internal combustion engine has a crankshaft, a camshaft driven by the crankshaft through a drivewheel at half the crankshaft speed and at least one cam on the camshaft for actuating a spring-biased poppet valve. To achieve variable event timing, a lost motion coupling is arranged between the drive wheel and the camshaft. During the opening of the valve, the camshaft rotates at substantially the same speed as the drive wheel, but during the closing of a valve, the camshaft is accelerated by the valve spring to lead the drive wheel and thereby reduce the duration of the valve event. It is alternatively possible to collapse the opening phase of the valve event rather than the closing phase by reversing the operation of the coupling.</p> |
