Drift of mechanical characteristics of Common Rail fuel lines during operating time

Abstract

During the operation of steel pipelines, there is a change, drift, in the characteristics of the materials from which they are made. In the field of technological pipelines and oil and gas complex pipelines, an extensive literature is devoted to this issue, including both scientific publications and regulatory state and industry documents. Changes in the material characteristics of high pressure fuel lines of internal combustion engines did not attract the attention of specialists. Fuel lines were an important component of engines, but at that injection pressure level, materials and technologies, which determine, inter alia, the cost of a component in the total cost of the engine, they remained outside the area of special attention. The development in Russia of its own production of Common Rail systems makes it necessary to study the behavior of parts under conditions of prolonged loading with an internal hydraulic pressure of 1600 kg/cm2 and higher. The drift of the characteristics of the materials of the high pressure fuel lines can be of great importance, in terms of the reliability of the fuel system and the whole engine. For the first time, studies were carried out of the mechanical characteristics of seamless steel pipes at various operating times on a non-motorized test bench under loading with an internal hydraulic pressure of 1600 kg/cm2 with a pulsation frequency of 45-55 Hz. It has been established that during running hours, the hardness in the cross sections of the fuel lines increases. The standard deviation of hardness values also increases, i.e. the spread of values is present. The nature of the change in the tensile strength and yield strength with an operating time of more than 1100 hours requires additional research. It is concluded that it is necessary to test a larger number of samples on the engine to find out the limiting values of the mechanical characteristics of the material.