DigitalAir™ Camless FVVA System – Part 1, Valve Train Design, Capability and Performance

Paper #:
  • 2017-01-0635

Published:
  • 2017-03-28
Abstract:
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. This paper will provide an overview of the JP Scope valvetrain including head, intake and exhaust valves, electric actuator and basic control algorithms. Results of analytical models used to predict the performance of the valvetrain will be presented and compared with experimental data. These include dynamic models created in Simulink that predict valve motion and power consumption, multi-physics models in ANSYS used to predict stresses and thermal distortion, and CFD models created in Converge to predict mixture motion and generate thermal boundary conditions for the multi-physics models. 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
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