DigitalAir™ Camless FVVA System – Part 2, Gasoline Engine Performance Opportunities

Paper #:
  • 2017-01-0641

  • 2017-03-28
The paper describes a completely new approach to fully variable valve actuation (FVVA), which allows almost unlimited continuously variable control of intake and exhaust valve opening and closing events, and duration without the use of a camshaft. This approach replaces conventional poppet valves with horizontally actuated valves located directly above the combustion deck of the cylinder head, which open and close a number of slots connecting the cylinder with the intake and exhaust ports. The stroke of the valves to provide the full flow area is approximately 25% of the stroke of the equivalent poppet valve, thus allowing direct electrical actuation with very low power consumption. This design arrangement avoids the risk of poppet to piston collision, or the need for cut-outs in the piston crown, since the valves do not open into the cylinder. The paper will present analytical and experimental data which confirms that the proposed FVVA system can meet the basic performance requirements of modern GTDI engines with respect to breathing characteristics across the speed range, unthrottled operation at and above idle, opening and closing event optimization, cylinder deactivation, control of residual gas fraction / scavenging and exhaust thermal management. Analytical results were developed using GT Power Cycle Simulation and Converge CFD. GT Power was used to study the system level performance, such as full load capability and transient response, and in particular to quantify the fuel consumption benefits of unthrottled operation over a realistic vehicle drive cycle. Converge CFD was used to better understand the opportunities for in-cylinder charge motion – tumble, swirl and turbulence and to study flame propagation, quenching and hydrocarbon emissions. JP Scope has been running experimental engines for several years and has successfully completed performance and durability tests, the results of which will be included Parts 1 and 2 of this paper.
Also in:
  • SAE International Journal of Engines - V126-3EJ
  • SAE International Journal of Engines - V126-3
SAE MOBILUS Subscriber? You may already have access.
Attention: This item is not yet published. Pre-Order to be notified, via email, when it becomes available.
Members save up to 36% off list price.
HTML for Linking to Page
Page URL

Related Items

Technical Paper / Journal Article
Training / Education
Training / Education
Training / Education