Experiment-based software optimization for cylinders consistency in electronic unit pump diesel engines

Besides the common-rail system, the electronic unit pump (EUP) is also being widely used in electronically controlled diesel engines. However, the EUP system is restricted for use in EURO IV diesel engine development, as its consistency of fuel delivery is hard to control accurately. As has been found in the case of the Chinese home-made EUP system, this problem is mainly caused by mechanical manufacture. In spite of the low-class hardware limit, this paper introduces a software method to correct the inconsistency of fuel delivery among EUPs at the whole range for engine running. First, the characteristics of inconsistency of fuel delivery among EUPs are determined based on a series of experiments. Second, an optimization algorithm with multi-point correction is proposed to adapt to the tendency for non-linear inconsistency. Finally, the algorithm is verified on the fuel pump testing platform, made by EFS company, and further on a YC6J diesel engine. The experiments demonstrate that the multi-point correction is not only able to weaken the inconsistency of fuel delivery among EUPs, but also improves both the idling control and the emission performance for an electronically controlled diesel engine. This paper also provides a successful example of an electronically controlled diesel engine where the consistency of fuel delivery from cylinder to cylinder is improved by this software optimization method.