Improvements to hardware:
Based on the findings from the proof-of-concept prototype, both promise and limitations have been realized. This portion of the project will focus on the design of an updated piezoelectric/hydraulic hybrid actuator for camless engine application. The updated design will address issues related to hydraulic flow path and inertia that were limiting factors of the prior design. Furthermore, the updated prototype will use two spool valves to better facilitate position, velocity, and acceleration control of the engine valve. Improved control over these parameters will result in less noise, lower valve wear, and increased operational frequency range. Precise control over valve displacement and open duration directly impacts the amount of fuel-air mixture input to the cylinder. This results in improved throttle control.
An actuator designed specifically to replace the camshaft of an internal combustion engine provides the opportunity for automotive manufacturers to develop truly variable timing. The introduction of variable valve timing to the consumer automotive market has significant implications. Such an engine will be able to produce greater power when necessary, for example entering onto a busy expressway. The same engine, through an adjustment of valve timing, will be capable of operating at considerable fuel savings during normal travel. It is also proposed that a camless engine will be able to reduce the harmful emissions of the typical consumer automobile.
Although these objectives and anticipated outcomes have been theorized by previous researchers, there has yet to be a camless engine development that has successfully transferred to mass production. This is due to several factors: actuator power consumption, repeatable valve position control, and limitation of frequency and/or valve displacement. The limitations of previous work have stemmed from a variety of design concerns; however, this proposed project intends to overcome these issues through the introduction of piezoelectric control of the valve actuator. As was proven during the first phase of Rocheleauís et al. work, piezoelectric stacks have the response and force to overcome many of the earlier problems. The inclusion of VTB will address Balance of Plant (BOP) issues to determine actuator power consumption issues. Further work will address the remaining issues allowing for the development of a production ready camless engine valve actuator.