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A continuously variable lift, duration and phase mechanical lift mechanism is described, as applied to the intake valvetrain of a SOHC, 4-valve per cylinder, four-cylinder production engine. Improvements in fuel economy were sought by reduction of pumping losses and improved charge preparation, and optimization of WOT torque was attempted by variation of intake valve closing angle. Adjustment of the mechanism is achieved by movement of the pivot shaft for the rocker arms. The relationship between lift, duration and phase is predetermined at the design stage, and is fixed during operation. There is considerable design flexibility to achieve the envelope of lift curves deemed desirable. The operation of the mechanism is described, as are the development procedure, testing with fixed cams, some cycle simulation, friction testing on a separate rig and dyno testing results for idle, part load and WOT.

A dual independent valve phasing mechanism is applied to an air-cooled, pushrod actuated, V-twin motorcycle engine with two cams. As described, the mechanism is manually adjusted. The design is readily adapted to automated control. The phasing concept mounts the roller lifter in an eccentric sleeve. Rotation of the sleeve advances or retards the position of the roller lifter relative to the cam lobe. This action in turn advances or retards valve timing. Valve lift and duration are essentially unaffected. Predicted and experimental results from varying valve phase under idle, part load, and full load conditions are presented. The effect of valve overlap on hydrocarbon emissions at idle and NOx emissions at part load are described. Changes in volumetric efficiency and torque at wide-open throttle operation are also described.

A novel mechanism using a moving rocker pivot has been developed by Motive Engineering. The chosen approach offers variation of lift, duration, and phase. A compact, robust proof-of-concept mechanism has been designed, and fabricated. It was fitted to the intake valvetrain of a production SOHC four-cylinder engine. The operation of the mechanism is described. A longer-duration, higher-lift camshaft was designed to explore the potential benefits of the concept throughout the speed and load range. Dynamometer testing has been done to explore possible benefits to power, fuel economy, and exhaust emissions.