Controlling Engine Load by Means of Late Intake-Valve Closing

800794

06/01/1980

Event
Passenger Car Meeting & Exposition
Authors Abstract
Content
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.
Meta TagsDetails
DOI
https://doi.org/10.4271/800794
Pages
16
Citation
Tuttle, J., "Controlling Engine Load by Means of Late Intake-Valve Closing," SAE Technical Paper 800794, 1980, https://doi.org/10.4271/800794.
Additional Details
Publisher
Published
Jun 1, 1980
Product Code
800794
Content Type
Technical Paper
Language
English