Development of a Model Test System for a Piston Ring/Cylinder Liner-Contact with Focus on Near-to-Application Seizure Behaviour

Abstract

Physical simulations of tribo contacts in internal combustion engines can act as a supporting tool to match upcoming guidelines and emission restrictions. In particular, the scuffing resistance of the contact between the piston ring and cylinder liner suffers under decreasing oil viscosity and limitation of antiwear additives. This paper aims to provide an experimental method to simulate the scuffing of the piston ring/cylinder liner-contact and to validate this method with real engine parts and the literature from engine tests. The experimental methodology uses a linear tribometer TE77 to test specimens from original piston rings and liners under reciprocating motion. Additionally, the ring specimen is given the opportunity to perform secondary movements (ring twisting, ring turning) and to run under deficient lubrication conditions similar to the engine. A specially designed test strategy enables the reproducible creation of seizure of the tribosystem. The seizure resistance of two engine oils, tested for validation, correlates with the known engine performance. Therefore, the model test system can be seen as a reproducible tool for simulating seizure of a ring/liner-system, showing similar trends and wear mechanisms as in an engine. Surface analysis depicts similarities between the scuffed surfaces of an engine and the model and discusses the origin of seizure based on the model specimens together with the relevant literature.