INSULATED PISTONS RAISE DIESEL EFFICIENCY

Future diesel engines must meet more exacting standards for exhaust emissions and noise with neither substantial cost increases nor need for exotic materials. One approach to these objectives is insulation of the engine combustion chamber to simulate adiabatic (occurring without loss or gain of heat) conditions. Theory predicts a possible improvement of up to 26% in thermal efficiency over advanced conventional diesel engines. Thermal energy could be converted to useful energy by a turbomachine in the exhaust gas stream. In addition to utilizing energy usually lost to cooling water, improved insulation should widen fuel tolerances, lower compression ratios, reduce white smoke, quiet combustion, reduce odor, particulates, HC, and CO, and improve utilization combustion chamber air. The article describes such a piston consisting of a hot-pressed Si//3N//4 top supported with a conventional aluminum base. The two components are separated by a highly insulating layer. They are bolted together, with Belleville springs used to compensate for differential longitudinal thermal expansion among bolt material, ceramic, and the aluminum. Axisymmetric finite element thermal and stress analyses were carried out for the adiabatic engine piston. Prototype testing of the adiabatic engine piston has begun, with design viability demonstrated.

Media Info

  • Pagination: p. 72-76
  • Serial:
    • Automotive Engineering
    • Volume: 86
    • Issue Number: 6
    • Publisher: Society of Automotive Engineers
    • ISSN: 0098-2571

Subject/Index Terms

Filing Info

  • Accession Number: 00183259
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Dec 12 1978 12:00AM