Factors determining the wear of locking conjugations of diesel engine injector nozzles

The article deals with the problem of choice of factors influencing the wear of sealing precision conjuga- tions of injectors used in diesel engines. Reliable data concerning these factors gives the possibility of their us- age for theoretical construction of mathematical model of conjugations wear and resource forecasting. A model of the system including the parameters characterizing the external influences on surface layers of the parts and the mechanical properties of surface layers is considered for the assessment of the factors affecting the wearing of injector sealing conjugations. Parameters characterizing the structure of surface layers of the parts are plas- tiсity and hardness of material surface layers, occurrence of surface imperfections of different scale like undula- lation or microroughness which are 0.001-400 mkm deep. Dependence defining the shock time on the lifting height of the needle, the needle mass, spring rate and acceleration, created by the presence of fuel in the gap was obtained as a result of the investigation. Dependences defining the energy accumulation at the surface layer of the parts and dependences defining the beginning of excessive wearing of the conjugation as a result of energy accumulation at the surface layer were also defined. The impact on changing the gap in the conjunction “needle - body spray” of actual contact surface was carried out. Thus in order to receive a mathematical model adequately describing the process of wear and life of injector sealing conjugations it is necessary to consider the parameters characterizing physico-mechanical properties of the fuel.