Varying the timing of intake-valve closing was examined on a single-cylinder engine as a means for controlling the load of a homogeneous-charge spark-ignition engine. The engine was operated unthrottled, with load control obtained by holding the intake valve open during a portion of the compression stroke. This allowed the piston to push part of the cylinder charge back into the intake manifold. Comparisons to a conventional engine showed the late intake-valve-closing engine to have (1) lower pumping losses, (2) lower specific fuel consumption, (3) lower nitric oxide emissions, and (4) similar HC emissions. However, the fuel-economy benefit offered by this load-control concept would be reduced by the frictional losses of a control mechanism. The current trend toward lower vehicular power/weight ratios also would diminish the impetus for this approach.

  • Supplemental Notes:
    • From SAE Meeting held June 9-13, 1980.
  • Corporate Authors:

    Society of Automotive Engineers (SAE)

    400 Commonwealth Drive
    Warrendale, PA  United States  15096
  • Authors:
    • Tuttle, J H
  • Publication Date: 1980

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00331763
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Report/Paper Numbers: SAE 800794
  • Files: TRIS
  • Created Date: Jul 9 1981 12:00AM