Nissan gasoline engine strategy for higher thermal efficiency

Abstract

Rising highly concern about the environment has led to demands for the improvement of the efficiency of gasoline engines. Engine thermal efficiency will reach about 40% by technologies as boosted EGR, miller cycle and so on. This evolution trend will be continuously required to survive engines for the future. In this background, further improvement based on theoretical thermal efficiency of high compression ratio and specific heat capacity should be promoted. In addition, energy loss reduction such as represented by cooling loss and friction is also very important for the efficient and effective improvement. NISSAN’s challenges will be introduced to solve these propositions.

Investigation on the response time of a self-regulation variable compression ratio engine

“…Since CO 2 emission is related to the combustion process occurring inside the engine, its reduction is inherently connected to lowering the fuel consumption (no matter the fuel type), meaning that the only way to reduce it in a given IC engine is to increase its overall efficiency (i.e., effective efficiency) over the total range of driving situations. One solution to do this for the spark ignition (SI) engine is to fit it with a variable compression ratio (VCR) system, which may be advantageously combined with other enhancingefficiency technologies (e.g., its combination with downsizing via turbocharging as explained in papers, 12,13 with Miller cycle as described in the literature 14,15 or even with electric hybridization. 16 )…”

“…Over the time, many reviews were authored on the subject of the VCR engine (e.g., 14,[17][18][19][20][21] ) Equally, many others were focused on presenting specific VCR concepts or prototypes. 13,15,[22][23][24][25] Out of them, very few focused on the dynamic response of the VCR engine, i.e., on the response time of the CR adjustment automatic system, even though this is paramount for the PC road mobility, which means anything but steady operation.…”