Indirect sensing technique for diesel fuel quantity control. Technical progress report, October 1--December 31, 1998

摘要

Work has proceeded intensely with the objective of completing the commercial prototype system prior to the end of the contract period. At the time of this report, testing and refinement of the commercial version of the system has not been completed. During this reporting period, several major milestones were reached and many significant lessons were learned. These are described. The experimental retrofit system has achieved all performance objectives in engine dynamometer tests. The prototype commercial version of the system will begin demonstration service on the first of several Santa Maria Area Transit (SMAT) transit buses on February 1, 1999. The commercial system has been redesignated the Electronic Diesel Smoke Reduction System (EDSRS) replacing the original internal pseudonym ADSC. The focus has been narrowed to a retrofit product suitable for installation on existing mechanically-governed diesel engines. Included in this potential market are almost all diesel-powered passenger cars and light trucks manufactured prior to the introduction of the most recent clean diesel engines equipped with particulate traps and electronic controls. Also included are heavy-duty trucks, transit vehicles, school buses, and agricultural equipment. This system is intended to prevent existing diesel engines from overfueling to the point of visible particulate emissions (smoke), while allowing maximum smoke-limited torque under all operating conditions. The system employs a microcontroller and a specialized exhaust particulate emission sensor to regulate the maximum allowable fuel quantity via an adaptive throttle- limit map. This map specifies a maximum allowable throttle position as a function of engine speed, turbocharger boost pressure and engine coolant temperature. The throttle position limit is mechanized via a servo actuator inserted in the throttle cable leading to the injection pump.