Analysis of Consecutive Fuel Injection Rate Signals Obtained by the Zeuch and Bosch Methods

The injection rate signals from a commercial diesel fuel injection system, based on a distributor pump driven by a DC motor, were characterised independently and consecutively by two injection rate meters based on the Zeuch and Bosch methods. The signals were first analysed in terms of their shot-to-shot variations over 64 consecutive injections and the correlations between needle lift and injection rate over a range of pump speeds and loads quantified by Fast Fourier Transform.

A direct comparison of the injection rate signals on a cycle-resolved basis was achieved by connecting two consecutive injectors from the pump-line-nozzle injection system to a Bosch- and a Zeuch-based injection rate meters. The signals were acquired over a large number of injections in terms of mean and rms of the injected quantity, mean injection rate, maximum injection rate, average cumulative fuel injected and average injection duration.

The results showed that in general the two methods provide an accurate estimate of the injected quantity per injection but that the injection rate signal is sensitive to the cut-off frequency selected for signal processing. Each of the two methods has advantages and disadvantages which are described and quantified for three pump operating conditions.