Application of Piezoelectric/Hydraulic Hybrid Actuators
This research project involves applying Phase-I Camless Engine (CLE) actuator technology, already developed in the AARG laboratory, to an operational Briggs and Stratton 90102 model single cylinder 4-cycle engine.
The goal is to actuate the intake gas exchange valve and provide an eye-opening example of the benefits associated with advanced actuator technology in the IC engine industry. Among other obvious advantages the benefits of Variable Valve Actuation (VVA) include increased fuel efficiency.
This research has the goal of monitoring the fuel consumption of the working prototype and showing the effect on fuel efficiency associated with this new PZT based method of intake valve actuation.
The project includes but is not be limited to:
Shown above is Richard Langdon measuring piston and valve displacement to generate mathematical models of their movement.
The Research is currently focusing on several areas. First, there is an ongoing effort to ensure that the measured valve displacement is repeatable and accurate. This effort will allow the generation of simulation algorithms for control purposes.
Additionally there are measurements needed for force output of the actuator at given frequencies and dimensional measurements for design work on the physical system.
The engine will be mounted on the hydraulic test stand adjacent to the position where the actuator is currently positioned and connected mechanically via the rocker mechanism. For a picture of the test stand and actuator, click here.
Research Update: July 29, 2003
The PZT application research project has advanced significantly. A brief description of the major advancements is presented:
1st) The measurements were made using the Brown & Sharpe CMM to obtain the standard valve lift versus crank angle profile for the Briggs & Stratton application engine.
The valve lift profile is shown below.
2nd) A Special Scott-Russell slider crank linkage was designed and manufactured in order to interface the actuator with the intake valve on the engine.
The figure below shows the linkage installed but not yet connected to the actuator.
3rd) An incremental optical encoder was procured from BEI and interfaced with the engine and controller to provide crank angle feedback. The interface was facilitated using Matlab/Simulink, Real Time Workshop, and a dSPACE DS1102 rapid prototype controller board. The figure below shows the encoder engine and actuator on the test bed.
4th) Tests were run to empirically tune the PID controller in order to minimize overshoot and rise time. These tests verified actuator capabilities while not connected to the linkage/valve. Once the KP, KI, and KD were properly selected for the controller, the linkage was connected and tests were run again to fine tune KP and KD thus accounting for the additional mass and friction of the Scott-Russell link and valve.
The first operational test of the Camless engine project is now expected in the immediate future. Once operation of the engine is achieved testing will begin to complete the application phase if the research.
Future research goals will then be established and posted herein.