Variable Valve Timing Investigation by Katie James Advised

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Variable Valve Timing

• Investigation by Katie James
• Advised by Professor Bruno
• Professor Krouglicof

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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

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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

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Effects of Reduced Fuel Consumption

• Pumping losses
• Combustion efficiency
• Minimal friction from Direct Injection
• Downsizing
• Higher pressure charging

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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

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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.

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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.

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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.

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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

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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

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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

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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

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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

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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

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Any Questions?