Variable Geometry Camshaft Scott Lake Matt Phillips Zachary Lightner Ryan Kowalewski Matt Griffey Sponsor: Gary Griffiths

Background of Invention Jaguar XJ6 Series 2 Engine CAD Model Development Dynamic Analysis

A standard cam has a single profile Profile dictates valve lift and duration –Optimal performance at one particular engine speed Optimal valve lift and duration vary throughout engine RPM range

Increased volumetric efficiency 4:1 Gear ratio mechanism for transferring torque from the input gear to the camshaft 180° of crankshaft rotation resulting in 90° of valve duration 240° of crankshaft rotation resulting in 120° of valve duration Fulcrum Rotation of no more than 24° Translational movement of rocker tower

Current Timing Chain

New Components Baseplate Tappet and tappet guide Fulcrum and bushings Camshaft

2900 mm N 50,000 mm N

Divide model into two portions at cam – rocker arm interface Observe deformation and Von Mises stresses at two distinct times: –Impact position (Cam initially makes contact with rocker arm) –Maximum Load position (Maximum normal force between cam and rocker arm)

ComponentMaterialYield Strength (GPa) Base Plate, Cylinder Head Aluminum Alloy Camshaft, Fulcrums, Rocker Arms, Tappets, Tappet Guides Cast Iron (ASTM 60)150 Rocker Arm Supports, Rocker Arm Pins 1020 Steel200

Number of Parts Number of Nodes Number of Elements Cam Portion (Impact Load) 1051,75525,903 Cam Portion (Step Load) 1051,78925,951 Rocker Arm Portion (Impact Load) 715,1026,607 Rocker Arm Portion (Step Load) 715,0806,609

0.016 seconds2956 N Impact Load: Maximum Load: seconds2956 N seconds5617 N seconds6452 N

Redesign of VGC system to be located outboard of tappet guide assembly Reduce generated forces by reducing separation distance, cam inertia Explore alternate 4:1 gear ratio designs Component Refinement – Redesign of high-stress components

APPENDIX

Patent Figures

Cam Contact

Patent Figures