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In a number of countries of the European Union the average age of vehicle fleet is over 15 years, and in the entire European Union vehicles are on average 11.1 years old. This means that the environmental parameters are largely determined by the technical condition of the current vehicle fleet and in particular by the condition of fuel systems operated over extended periods of time. The article examines the changes in the behaviour of electromagnetic nozzles of Common Rail fuel system as a result of irreversible wear and deformation, which in turn affects the hydraulic characteristics and controllable fuel supply parameters. The influence of the changes in the electromagnetic nozzle’s adjustable geometric clearances on the injected fuel and the dephasing of this process in relation to the moment of transmission of the control pulse are examined. An analysis of the impact of these phenomena on the work process development in terms of deterioration of the vehicle’s environmental characteristics is made.

The study and modeling of the combustion process of diesel engines require knowledge of the injection characteristics. The information on the exact start, duration and end of the injection is required. For Common Rail injectors with electromagnetic control, the beginning and duration of the electronic control pulse are precisely known. The actual start and duration of the injection are not the same as those of the impulse and they are related to the movement of the nozzle needle. The experimental determination of the movement of the nozzle needle requires specially prepared experimental installations and expensive measuring instruments. In addition, the experimental injector must be prepared with design modifications allowing the incorporation of sensors. The article presents a method for determining the start and duration of injection of Common Rail injectors using the registration and analysis of vibration pulses generated in the injector body. The method is based on the fact that the nozzle needle causes vibrations in the injector body when lifting and seating.

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