F2008-06-104
An Innovative Variable Valve Event and Lift System (VVEL) for New Nissan V6 and V8 Engines
The most important proposition for sustainable mobility is to dramatically reduce the environmental impact of vehicle use, especially by reducing carbon dioxide (CO2) emissions that are one cause of global warming. This aim can be achieved by saving energy, i.e., improving fuel economy, as well as through cleaner emissions. On the other hand, customer demands for higher dynamic performance are continually increasing, making this attribute ever more crucial to product appeal. One of the technologies that enhance environmental and driving performances at the same time names a variable valve system, which controls intake and exhaust valve timings and lifts. Nissan Motor adopted in 1986 the Japan-first hydraulic variable valve timing control system (VTC). Since then, Nissan has adopted the cam-switching-type variable valve lift and timing system (VVL) and the electromagnetic VTC to advance the technology with finer control. At Nissan, we have recently developed a new variable valve event and lift (VVEL) system that continuously controls both the intake valve lift and event angles (valve opening and closing timing) over a wide range. Combined with conventional variable valve timing control (VTC) technology, this VVEL system optimally controls the intake valve timing and lift to match engine operating conditions. This technical innovation facilitates well-balanced improvement in the major parameters of engine performance. This paper describes the basic configuration of the VVEL system, kinetic and tribologic characteristics of VVEL´s multi-rink, the manufacturing technology for mass production and its electrical control system by high efficiency ball-nut reduction and DC electrical motor. Then, the resultant effects on improving overall engine performance as fuel economy, low emission, engine performance and generation of driving pressure is introduced. It also explains expanding the application of the VVEL system from V6 to V8 engines and its issue as different input force for V8 VVEL. The future prospect of this VVEL technology is also discussed.
Session: Engine Mechanics