Method and apparatus for controlling fuel injection timing in a

Abstract

The method and apparatus for generating start of combustion signals associated with the combustion events in a diesel engine (10), and for using such signals to control the timing of fuel delivery to the engine. The combustion event is sensed, as by an electrostatic (230, 330) or optical (130, 430) sensor, and signal conditioning circuitry (32) provides a start-of-combustion (SOC) signal (34) which is directly and precisely indicative of the time of the onset of combustion. The sensors (130, 230) include self-cleaning capabilities (48, 248) for extended operating life on an engine. The sensors may be incorporated in the structure of a glow plug (330, 430). The SOC signal (34) is advantageously supplied to a timing control circuit (26) which delivers a timing control signal (28) to a fuel delivery device, such as the controller (16') associated with a fuel pump (16). The control circuit (26) stores (65) one or more start of combustion values (SOC*) which indicate the desired timing, relative to an engine cycle (24), for the start of the combustion event as a function of speed (25) and load (27). One or more adjustment signals (.DELTA.SOC) are stored (75) and applied (67, 68) as a function of speed and load to adjust the desired signal (SOC*) such that the control signal (28, SOC.sub.c) is corrected for delays. The actual SOC signal (34) is compared (71) with the desired signal (66) to generate an error signal (72) which may be used to finely adjust the stored (75) .DELTA.SOC signal for particular speed and load conditions.