ADJUSTABLE STROKE LENGTH AND COMPRESSION RATIO ENGINE

Resumo

Recently, research on internal combustion engines for the automobile industry aims the increase of efficiency. The main motivation is the environmental regulations, which are being adjusted to force an urgent reduction in the vehicular emission of pollutants. Among the technologies in development that bring an increase in the efficiency of engines, it can be highlighted the strategies used to adjust the compression ratio according to the operational requirements of the engine. Another strategy is to reduce the opening/closing of the throttle valve to limit the output power by adopting an alternative, being by means of adjusting the valve synchronism or by means of varying the stroke length and thus varying the cubic capacity, resulting in the maintenance of a higher pressure in the intake manifold and avoiding the negative pump work. This work presents a mechanism that allows the adjustment of both compression ratio and stroke length. Therefore, the engine can operate at partial loads without restricting the flow to the intake manifold and the compression ratio can vary to obtain a higher efficiency when there is no risk of the knock to occur and also, it is possible to guarantee a better adaptability, fundamental requirement for a multi-fuel engine. The proposed engine is described, showing and explaining the strategy adopted and, following, a preliminary study made by computational simulation is presented, illustrating and justifying how the technology has the potential to increase the efficiency of spark ignition engines.