Optimization of FreeValve´s fully variable valve control system for a four-cylinder engine

Abstract: Automotive exhaust legislation is stricter than ever and manufacturers are spending increasing amounts of resources on reducing fuel consumption and emissions from their vehicles. What most do not try is to change one of the most fundamental concepts of the internal combustion engine. The camshaft is used to control the poppet valves in the gas exchange process and has, despite many variations, stayed more or less the same the last century. The largest disadvantage with the camshaft is that the optimum gas exchange process is dynamic with engine speed and load, where the camshaft is not. Variable valve timing as many manufacturers explored reduces the problem but in order to get the real advantages a fully variable valve timing system is needed. FreeValve AB is a small Swedish company that develop such system which is based on a Pneumatic Hydraulic Electric Actuator to operate each valve. The aim of this Master’s thesis was to re-design the FreeValve electric valve control system to suit new and updated requirements of running a four-cylinder engine in a car. The circuit design process of the system is presented along with a literature study to identify design considerations for a future valve control system prototype to operate in the demanding environment of an engine compartment. A requirement specification was established and it was verified that the parts of the system within the scope of the project were successfully designed according to the literature review and specification, with the main task to deliver the correct current profile to the valve actuators.