OPTIMIZER INVOKES ADAPTIVE STRATEGY FOR BEST SPARK ADVANCE

Applied to ignition timing, the Optimizer seeks out that spark advance yielding maximum rpm at any given load. Its "dithering" routine oscillates spark advance ever so slightly, while a single sensor monitors corresponding changes in engine speed. A logic module analyzes the effect of dithering and adjusts spark advance incrementally in the direction of increasing rpm. At its current level of refinement, the Optimizer also incorporates a bias adjustment to avoid incipient knock and to enhance compatibility with EGR (Exhaust Gas Recirculation). A recent evaluation by the National Bureau of Standards' Office of Energy-Related Inventions notes that "the Optimizer offers a reasonable potential for fuel economy improvements very conservatively estimated at 10%" . The Optimizer is designed on the basis that the spark timing giving the highest rpm for a given load is MBT (Minimum advance for Best Torque) timing, and that an engine ignited at MBT is running most efficiently. This second point, though, needs some qualification. For a given engine at some particular load, MTB timing may generate conditions of incipient knock. This was found especially so with engines using EGR (Exhaust Gas Recirculation) for NOx control. The original design has been modified to allow a timing target retarded somewhat from MBT. A state-of-the-art Optimizer is currently being evaluated in a Dodge Aspen. Initial expectations of fuel economy improvements are said to be in the range of 20%.

Media Info

  • Pagination: p. 36-39
  • Serial:
    • Automotive Engineering
    • Volume: 86
    • Issue Number: 7
    • Publisher: Society of Automotive Engineers (SAE)
    • ISSN: 0098-2571

Subject/Index Terms

Filing Info

  • Accession Number: 00183268
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Dec 29 1978 12:00AM