A Study of a Multiple-link Continuously Variable Valve Event and Lift (VVEL) System

A new variable valve event and lift (VVEL) system has been developed by applying a multiple-link mechanism. This VVEL system can continuously vary the valve event angle and lift over a wide range from an exceptional small event angle and small lift and to a large event angle and large lift. This capability offers the potential to improve fuel economy, power output, emissions and other parameters of engine performance. The valve lift characteristics obtained with the VVEL system consist of a synthesis of the oscillatory motion characteristics of the multiple-link mechanism and the oscillating cam profile. With the multiple-link mechanism, the angular velocity of the oscillating cams varies during valve lift, but the valve lift characteristics incorporate both gentle ramp sections and sharp lift sections, the same as a conventional engine. This paper describes the mechanical features of the multiple-link VVEL system and performance levels attained, based on simulation data obtained at the stage of conceptualizing the fundamental principle of the system and at the stage of validating a prototype system.