Method of specifying an injection-pressure setpoint value in an accumulator injection system

摘要

An injection-pressure setpoint value for the pressure accumulator of an accumulator injection system is specified as a function of the operating point of the engine. The setpoint is specified with the aid of respectively separate characteristic diagrams for the start, idling and load engine operating states. In load operation, the profile of the injection-pressure setpoint value is additionally adapted to the particular requirements of the transient engine operation with a first timing element whose timing characteristics depend on the engine speed. The profile may be briefly raised out of a low engine speed in the case of an acceleration. With the aid of a downstream, second timing element which is independent of the first timing element, sudden transitions in the specification of the setpoint values when the engine operating state changes are suitably smoothed out. Any jumps in the injection-pressure setpoint value are avoided. The gear which has been engaged or the driving style of the driver can be taken into account in the transfer characteristics of the second timing element.