METHODS FOR DETERMINING FUEL BULK MODULUS IN A HIGH-PRESSURE PUMP

摘要

Methods are provided for finding the bulk modulus of a fuel used in the direct injection system of an internal combustion engine. A method is needed to continuously monitor and reliably calculate the fuel's bulk modulus during engine operation on-board the vehicle, where the fuel's bulk modulus may be used to infer the ratio of fuels in a fuel mixture or determine the density of supercritical propane when propane is used as the injected fuel. To find the fuel's bulk modulus on-board a vehicle, methods are proposed that involve monitoring and recording fuel rail pressures, high pressure pump duty cycles, and fractional liquid volume pumped values in order to find zero flow relationships.

主权项

1. A method, comprising:
adjusting duty cycle of a high pressure pump to measure a bulk modulus of a fuel based on a zero flow function for the high pressure pump, the fuel being pumped through the high pressure pump and the zero flow function based on a change in pump duty cycle relative to a resulting change in fuel rail pressure.