The modelling of a diesel fuel injection system for the non-intrusive monitoring of its condition

In this paper a finite difference scheme has been developed and applied to the modelling of a diesel fuel injection system. With the high-pressure pipe divided into many reaches, the partial differential equations governing the pipe flow are discretised into ordinary differential ones, which are in the same form as those representing the pump and the injector so that all the equations are solved simultaneously at each time step. Numerical results for a distributor-type injection system and influences of fuel injection faults have been simulated. It is observed that the pressure at approximately the end of the pipe close to the injector (p(pn)) is almost the same as the pressure in the nozzle chamber (p(n)). Therefore, indirect measurement of p(pn) by a clamping sensor around the pipe can provide an alternative non-intrusive means rather than direct measurement of p(n) by an intrusive pressure transducer. The monitoring capability of the pipe pressure p(pn) by indirect measurement has been verified by a preliminary experiment on a production diesel engine. This investigation provides a tool for the non-intrusive monitoring of a diesel fuel injection system.