Simulation studies to maximise measurement data quality of engine rubbing friction - methods based on pressurised motoring

Abstract

Rubbing friction between moving components of an internal combustion engine can be measured using methods such as the Teardown test, Hot coasting, Morse test and the Fired, or Motored Indicating methods. These known methods have their own deficiencies in providing faithful measurements, with some being highly limiting. Methods based on the fired engine are ideal since they provide a measurement that is sensitive to all the contributing variables, and their interaction. Fired measurement methods however suffer in robustness and repeatability. The alternative solution is the use of motored methods which are known to offer good robustness and repeatability, however lack in the representation of the actual fired phenomena on the rubbing friction. This paper presents a simulation study, backed by experimental data, of a motored indicating method known as “Pressurised Motoring”, modified in two distinct ways to increase the representation of the fired friction mechanisms on the motored rubbing friction measurement, whilst taking advantage of the robustness and repeatability of the motored method. Results showed that the proposed two variants of the method (“Argon Mixtures Method” and “Fuelled Pressurised Motoring”) offer better representation of the fired engine in various ways, whilst retain the robustness of the rubbing friction measurement.