Examination of fast-changing quantities in engine with common rail injection system

The paper aims to present the results of investigations into the engine with Common Rail system that performs multi-phase injection. The scope of investigations included measurements and assessment of fast-changing quantities. The paper provides the research stand description and a block diagram o f the system for taking measurements offast-changing quantities, including the system measuring the intensity of the current that controls the injector operation. The experimental results discussed in the paper were derived from introductory investigations into measurements of the air-fuel mixture pressure in the engine cylinder and those of the injector needle lift, which were assessed on the basis of measurements of the intensity of the injector-controlling current. Tests were performed while the engine operated under external speed characteristics and under load characteristics at the crankshaft rotational speed n=l200 rpm and n =3800 rpm. During tests, depending on speed and load characteristics of the engine operation, the ECU performed different strategies of fuel injection. The fuel injection control system madę it possible to complete three injection stages in a single work cycle of the internal combustion engine (pilot injection, pre-injection and the main injection). The maximum fuel pressure in the common rail amounted to 160 MPa. The engine was fuelled by commercial diesel oil.