Hydraulic Variable Valve Timing Testing and Validation
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Date
2016-06-30
Authors
Chermesnok, Matthew
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
This thesis documents the development of a fully continuous, hydraulics-based variable
valve timing system. This hydraulics based variable valve timing system is capable of
controlling an engine valves lift height and infinitely varying the engine valves lift profile.
Along with full valve controllability during normal operation, the variable valve timing
system is capable of providing the same operation as a classic cam shaft under engine
power loss conditions. This is possible due to the rotating hydraulic spool valves coupled to
the engines crank shaft, which are used to actuate the engine poppet valves.
The main focus of this thesis is to investigate, alter and implement a new iteration of the
hydraulic variable valve timing system on a standalone test bench to validate the systems
operating principles. The test bench utilizes servo motors to act as an engines crank shaft
which runs the rotating hydraulic spool valves and hydraulic pump. This serves as an
intermediate step to full engine implementation of the variable valve timing system.
The research begins by analyzing the current mechanical spool valve and hydraulic cylinder
design for any potential problems that may occur either during assembly or full operation.
The basic system equations are presented to give a glimpse into the working principles of
the rotary valves. The mechanical, electrical, and hydraulic subsystems are discussed in
terms of what was considered during the design and implementation process. Then design
changes that were performed on the rotary valve system to overcome any failures. Lastly
the resulting data is presented from the current variable valve timing design to verify proper
system functionality.
Description
Keywords
Variable Valve Timing, Hydraulic Valve Timing, Valve lift control, Valve timing control, Engine Valvetrain, Variable Valve Actuation, Phase Shifting