Start-of-injection-based software optimization for consistency between the cylinders in common-rail diesel engines

Abstract

A common-rail system is widely used in electronically controlled diesel engines and has been used in Euro IV diesel engine development, as its consistency between the fuel injection quantities of the injectors can be controlled accurately. In Chinese home-made common-rail systems, the bottleneck is mainly caused by the mechanical manufacturing, which results in variation in the fuel injection quantity of different injectors. In spite of the low-class hardware limit, this paper introduces a software method to correct the inconsistency between the fuel injection quantities of the injectors over the whole range during which the engine is running. First, the main factor affecting the inconsistency between the fuel injection quantities of the injectors is determined on the basis of a series of experiments. Second, an optimization algorithm based on the start of injection is proposed to compensate for the difference between the injectors. Finally, the algorithm is verified on an EFS 8246 fuel-pump-testing platform and further on a YC6A diesel engine. The experiments demonstrate that the correction based on the start of injection not only can reduce the inconsistency between the fuel injection quantities of the injectors but also can improve both the idling control and the emission performance for the electronically controlled diesel engine. This paper also provides a successful example for improving the consistency between the fuel injection quantities from cylinder to cylinder in an electronically controlled diesel engine by this software optimization method.