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Controlling Engine Load by Means of Late Intake-Valve Closing
ISSN: 0148-7191, e-ISSN: 2688-3627
Published June 01, 1980 by SAE International in United States
Annotation ability available
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.
Results showed that to achieve the range of load control required for vehicular operation, late intake-valve closing would have to be combined with variable-density throttling. 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.
|Technical Paper||Controlling Engine Load by Means of Early Intake-Valve Closing|
|Technical Paper||Effect of Variable Engine Valve Timing on Fuel Economy|
|Technical Paper||Variable Valve Closure Timing for Load Control and the Otto Atkinson Cycle Engine|
CitationTuttle, J., "Controlling Engine Load by Means of Late Intake-Valve Closing," SAE Technical Paper 800794, 1980, https://doi.org/10.4271/800794.
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