Measurement methods for determining the parameters of injectors in internal combustion engines

The general principle of internal combustion engine operation has not changed since the engine structure was first developed. However, the system of blending the air and fuel into a mixture with the parameters ensuring effective fuel combustion processes has been evolving over the years. In the simplest engines, the fuel-air mixture was produced in the inlet manifold i.e. in the carburettor systems while the more advanced motors were equipped with the system of Single Point Injection (SPI), and further on with the Multi-Point Injection (MP!) where each of the cylinders has its own individual injector. The Multi-Point Injection (MPI) system has evolved into a Gasoline Direct Injection (GDI) system where the injector sprays fuel directly into the combustion chambers. Presently, due to the restrictive regulations governing the issues of exhaust gases ' composition and emissions, manufacturers of the engines used mainly in the automotive industry apply the system of multi-point indirect injection to the intake manifold or the system of direct fuel injection to the combustion chambers. In both systems, these are the injectors dosing precise amounts offuel, which are the most important, and the most accurate elements of the system. The article presents the injectors' macro- and microscopic parameters used for the purpose of the fuel dispersants' technical condition and performance assessment. Additionally, it refers to direct and optical methods of microscopic parameters measurement enabling fuel spray diagnostics.