Hydraulic Variable Valve Timing Testing and Validation

This thesis documents the development of a fully continuous, hydraulics-based variable \nvalve timing system. This hydraulics based variable valve timing system is capable of \ncontrolling an engine valves lift height and infinitely varying the engine valves lift profile. \nAlong with full valve controllability during normal operation, the variable valve timing \nsystem is capable of providing the same operation as a classic cam shaft under engine \npower loss conditions. This is possible due to the rotating hydraulic spool valves coupled to \nthe engines crank shaft, which are used to actuate the engine poppet valves. \nThe main focus of this thesis is to investigate, alter and implement a new iteration of the \nhydraulic variable valve timing system on a standalone test bench to validate the systems \noperating principles. The test bench utilizes servo motors to act as an engines crank shaft \nwhich runs the rotating hydraulic spool valves and hydraulic pump. This serves as an \nintermediate step to full engine implementation of the variable valve timing system. \nThe research begins by analyzing the current mechanical spool valve and hydraulic cylinder \ndesign for any potential problems that may occur either during assembly or full operation. \nThe basic system equations are presented to give a glimpse into the working principles of \nthe rotary valves. The mechanical, electrical, and hydraulic subsystems are discussed in \nterms of what was considered during the design and implementation process. Then design \nchanges that were performed on the rotary valve system to overcome any failures. Lastly \nthe resulting data is presented from the current variable valve timing design to verify proper \nsystem functionality.