Abstract
Nissan's Variable Valve Event and Lift (VVEL) system has been developed as a technology for achieving both environmental friendliness and dynamic performance in automotive engines. This system can continuously vary intake valve lift, event angle (valve opening duration) and phase angle over a wide operating range to flexibly control the valve timing and lift for a substantial improvement in engine performance. VVEL system has been applied to some models of Nissan’s V6 and V8 engines. This time we have modified the VVEL system and applied it to a newly developed direct injection V8 gasoline engines, and performance improvement is obtained by synergism of VVEL system and direct injection. This paper describes the improvements in mechanism of VVEL system, its advantages in engine performance and countermeasures to problems which were realized when VVEL was applied to V8 engines with direct injection system. It also explains application examples of new mechanical and dynamic stress simulation tool with finite element method (FEM) explicit scheme which is newly developed in order to study reliability and durablity in a short term. Furthermore, in-cylinder air quantity control method which is the basis of newly developed control system for engine with VVEL system is explained
Keywords: Variable valve event and lift, Direct injection, SI engine, Mechanism analysis, Air quantity control