Calculation and Design of Common Rail Injectors with considering their Longitudinal Compliance

The experience of creating electro-hydraulic Common Rail injectors led to the conclusion that the longitudinal deformation of their parts affects the fuel supply performance. The paper presents additions to the mathematical model of fuel supply in a diesel accumulator system. These additions describe the deformation of the injector parts. The longitudinal compliance of the parts changes the course of the needle, the volume of the cavities. As shown by the analysis of the operation of three electro-hydraulic injectors, longitudinal compliance leads to an increase in the injection start delay up to 2,0...2,5° of the camshaft turn, an increase in the needle stroke up to 40 %, an increase in injection pressure, a reduction in its duration, and difficulty in organizing multiple fuel injection. The comparison with experimental data and finite element calculations showed the applicability of the supplemented mathematical model as a part of the general model of fuel injection in diesel systems. Its use allows creating more valid tools for calculating fuel supply processes and taking into account compliance when designing Common Railinjectors.