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

2. 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

3. 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

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

5. 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

6. 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.

7. 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.

8. 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.

9. 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%

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

11. 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

12. 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

13. 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

14. 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

15. Any Questions?