Apparatus for ascertaining control variables in an internal combustion

Abstract

An apparatus for ascertaining open- and closed-loop control variables of an internal combustion engine, in particular a Diesel engine, on the basis of individual operating characteristics. The individual open- and closed-loop control variables are each ascertained in an individually computer-controlled manner immediately prior to their being needed. This manner of determining the individual values is particularly amenable to realization in large Diesel engines which operate relatively slowly, but it is applicable in principle to all types of internal combustion engines. The proposed apparatus includes an rpm regulator having a subsequent minimum-value selection circuit and calculation circuits for the onset and the duration of injection. Cylinder selection circuits for controlling the rotary direction are also provided. They determine both the particular metering valve being used and the corresponding starting-air valves for controlling the starting process. For the sake of providing precise fuel metering, the opening duration of the metering valves is made dependent on the fuel pressure prevailing at a particular time. What is of the essence in the apparatus is that the fuel requirement at a particular time is determined immediately prior to the metering thereof, and thus the time required for reacting to changed circumstances is reduced to a minimum.