Variable Valve Timing Investigation by Katie James Advised by Professor Bruno & Professor Krouglicof

Variable Valve Timing (VVT) Use In Internal Combustion Engines Arising Constraints Impose New Standards The Evolving IC Engine Current Advancements and Developments Future Applications Progressive Intellectual Capital at Union

Spark-Ignition Focus Many factors have steered commercial market away from standard IC-engine with spark-ignition Growing competition from alternative power sources More efficient fuel consumption due to heightened emission restrictions Individual company commitments toward higher performance demands and safety regulations without compromising comfort level or retail value

Effects of Reduced Fuel Consumption Pumping losses Combustion efficiency Minimal friction from Direct Injection Downsizing Higher pressure charging

Thermodynamic Solutions Thermodynamic conditions must operate at higher loads Or reduce gas exchange/heat loss at part load Supercharging Turbo-charging Fully Variable Valve Timing Direct-Injection

Current Design: Delphi Automotive Systems Cylinder Deactivation System Enables cut-out of half cylinder count to boost fuel economy. Intake stroke of exhaust valves are disabled with target cylinders using oil pressure or electric solenoids Simultaneously FI is cut off to target cylinders “Forward-tumble Direct-Injection”- A/F mixture stabilized near ignition source zone Produces 8 to 10% decrease in emission levels.

Current Design: Motronic D-I System VW Golf 1.6L Direct-Injection SI Engine Generates pressure in full rail that supplies electromagnetically controlled injector with gasoline. Fuel quantity is controlled and adjusted to intake-air mass using information from wide-band oxygen sensor.

Variable Valve Timing VVT avoids exchange losses due to charging. Electromechanical valve train surpasses improvements made by port-fuel-injected gasoline engines because variability allows for precise air/fuel intake.

Current VVT Design: Siemens VDO Variable Valve Lift Control (LVC) Elimination of throttle valve Able to restore energy lost due to gas exchange work normally performed by throttle valve Gas exchange directly controlled by intake valve Variability provided using electromagnets Allowing valve timing to be infinitely (fully) adjustable ** Reducing fuel consumption up to 10%

Current VVT Design: i-VTEC by Honda New “intelligent” valve control adding Variable Timing Control (VTC) Continuously adjusts camshaft phase to both VVT and lift electronic control on intake valves Varies lift and actuation time of intake opening: Adjusts optimal cylinder filling in low rpm settings; staggered valve timing and asymmetrical lift Impressive high rpm power output Performs continuously variable camshaft “phasing” across entire engine band VTC actuation controlled by cam position, ignition, exhaust and throttle position

Additional VVT Design Highlights BMW goes throttleless with Valvetronic Infinitely adjusts intake valve lift First production gasoline unit without throttle butterfly 85kW engine consumes 1.8gal in 62mi (0.2gal reduction) Transition from carburetors to fuel injection, from two to four valve technology, and mechanical to electrical engine management

Additional VVT Design Highlights Bugatti incorporates VVT into two V8 cylinder blocks 64 valves operated by overhead camshafts cia electrohydraulic continuously variable control system Coordination of engine handled by two interdependent computers per cylinder bank* Quad-turbo 16 cylinder power plant yielding highest peak torque in production passenger car

Movement towards Efficiency Many companies have shifted away from throttle to improve efficiency Hydraulic actuation and electronic control is incorporated All available VVT advancements still involve camshaft or rocker arm

One Step Ahead: Progressive Engine Research Research Test Bed Take throttleless design Integrate camless actuation device replace with electrohydraulic servomechanism Hydraulic Power Unit LVDT: Linear Displacement Transducer

Any Questions?