ELECTRONIC-FUEL-INJECTION-SYSTEM ENRICHMENT CIRCUIT FOR USE DURING ENGINE CRANKING

摘要

ELECTRONIC-FUEL-INJECTION-SYSTEM ENRICHMENT CIRCUIT FOR USE DURING ENGINE CRANKING An electronic-fuel-injection-system enrichment circuit for use during cranking of an internal combustion engine having a fuel supply controlled by the fuel injection system. The fuel injection system produces a fuel control electrical signal representative of a quantity of fuel to be injected into the engine. An enrichment circuit, for use during cranking of the engine to increase the quantity of fuel represented by a fuel control electrical signal, is provided. This enrichment circuit includes circuit means for generating an enrichment electrical signal having a characteristic which varies with time subsequent to initiation of cranking of the engine and circuit means for combining the enrichment electrical signal with at least one other electrical signal representative of a fuel quantity to be injected into the engine. The combined electrical signals produce the fuel control electrical signal. The variability with time of the enrichment electrical signal during cranking of the engine tends to increase the quantity of fuel represented by the fuel control electrical signal. The enrichment electrical signal may vary in discrete steps as a function of time. Subsequent to the start of the engine, the enrichment signal may vary with time in a manner tending to decrease the quantity of fuel represented by the fuel control electrical signal.