A New Tribometer for the Automotive Industry: Development and Experimental Validation

In automotive engineering, the piston ring-cylinder liner pair is among the most studied contacts. From the three piston rings of a conventional internal combustion engine, the top compression ring has a crucial role. The main challenge is to prevent that during the engine lifecycle, the degradation of the piston ring surface might limit the engine’s durability. However, a reliable evaluation of the piston rings tribological response requires a steady method. To test and study the tribological performance of the ring-liner pair, the development of a customized test rig is presented in this work. The new oscillating tribometer will test and study the performance of new and commercial piston rings and cylinder liner solutions. According to the foreseen engine operation, four conditions were appointed to perform the control tests, and a testing protocol was established. The selected stainless-steel piston rings were coated with a diamond-like carbon layer, and the cylinder liner parts had the typical plateau honed texture in the contact surface. The friction force measures were recorded. It was also investigated the influence of distinct parameters (such as temperature and contact pressure) in the friction coefficient of this pair. According to the exploratory tests, the major COF was registered for the testing condition with a lower load. In contrast, the lower COF values were recorded for those conditions with superior normal loads and temperatures. The functionality of the developed test rig was verified to evaluate the ring's performance and the liner contact.