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A new variable valve actuation system that varies valve lift and timing events continuously has been devised and confirmed to substantially improve power and reduce fuel consumption when applied to a SI engine. The variable valve event and lift (VEL) system is a simple mechanism consisting of oscillating cams and linkages, enabling it to operate the valves smoothly even at high speed. Its compact size facilitates application to direct-acting valve trains and its ability to vary valve lift from a deactivated state (0) to a large lift amount allows the system to be used with a wide range of engine concepts. In this study, VEL was combined with a phase shifting function to enable the valve lift characteristic to be varied virtually arbitrarily, and test results showed that fuel consumption of a SI engine was reduced by nearly 10%.

This paper describes a new variable valve system that enables continuous control of valve events, i.e. time periods when the valve is open. In this system, valve events are controlled by varying the camshaft angular speed by means of an offset between the center of the camshaft and that of the medium member that transfers crankshaft torque to the camshaft. The medium member, a rotating disk, has a drive pin to enable the transfer of torque. The system has a mechanism that produces an offset between the center of the rotating disk and that of the camshaft as well as an actuator that drives the mechanism. This makes it possible to develop a compact system that can be installed in existing DOHC direct-acting valve train engines without making any major cylinder head modifications.