Abstract
Designing of engine is normally concerned on the power band to be suitable for usage such as low, middle and high speed. The above mentioned speed will be used in tractors, passenger cars and racing cars respectively. Even though the engine is well and suitably designed, the effectiveness of power band should be approximately 60 -<100 percent. This assay will be therefore prepared for testing the fundamental possibility in controlling the air flow rate by increasing and decreasing the duration of intake and exhaust valve with variable valve actuation mechanism that is considered to be one of the most suitable solutions to realize the compatibility between higher power output and performances in the practical speed range . A new variable valve actuation mechanism named Continuously variable valve duration mechanism
was designed and studied by the following development targets were set for the valve actuation system .
1. The mechanism should be secured up to a high speed .
2. A mass increase of the mech anism should be minimized .
3. The mechanism should be a compact .
4. The mechanism should be a simple .
5. The mechanism should achieve high reliability and durability .
The mechanism should be enabled to be mass produced with a minimal . In this mechanism which was applied to a conventional motorcycle engine with eccentric rocker shafts system . Consequently valve duration, valve lift and lobe center varies continuously in accordance with the eccentric rocker shafts ratio . Result of the experiments has confirmed that the mechanism functions and some improvements were achieved in power output, torque, fuel consumption, emission and idling quality .