Realization and optimization of high compression ratio engine with electromagnetic valve train

Abstract Internal combustion engines still play an important role in today’s low carbon society. Further improvement of engine thermal efficiency can be obtained by increasing geometric compression ratio (GCR), but it is limited by the knock especially for gasoline engine. While the application of moving coil electromagnetic valve train (EMVT) on engine intake and exhaust system provides new potential to realize a high compression ratio. Based on this, a later EVO strategy is carried out in this work to enhance the scavenging effect. As a result the residual gas rate and initial temperature in cylinder have a great decrease, which can depress the knock tendency effectively. Then coupled with the utilization of earlier IVC and larger air fuel ratio (AF), the power loss and high fuel consumption caused by the delay of ignition timing can be prevented. Finally, an optimization scheme combining engine thermal model, EMVT model and genetic algorithm program is proposed to optimize the engine GCR and operational parameters. Researches are mainly carried at the typical low speed of 1000 rpm and the results show that the most appropriate GCR is 13.5. With the optimum operational parameters the engine thermal efficiency has an obvious improvement, at full load the torque has not declined and the BSFC decreases by 3.3%; at partial load the BSFC decreases by 3.3–11.8%.