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When evaluating the wear properties of slide bearings for car engines, it is a common practice to conduct long-term physical test using a bearing tester for screening purposes according to the revolution speed of the shaft, supply oil temperature and bearing pressure experienced in the actual use of engines. The loading waveform applied depends on the capability of the tester that is loaded, and it is often difficult to apply a loading waveform equivalent to that of actual engines. To design an engine that is more compact or lighter, it is necessary to reduce the dimensions of slide bearings and the distance between bearings. This requires loading tests on a newly designed engine by applying a loading waveform equivalent to that of actual engines to slide bearings and their vicinity before conducting a firing test. We therefore conducted an engine firing test by attaching thin-film sensors to the slide bearing part of the engine and measured the actual load distribution.

Piston ring wear in gasoline engine induces deterioration of emissions performance due to leakage of blow-by gas, instability of idling caused by reduced compression in combustion chamber, and to generate early degeneration of engine oil. We examined anti-wear performance of DLC coating on piston ring, which had been recently reported as an effective method for improving the abrasion resistance. As a result, wear rate remained low under the condition of DLC existence on sliding surface, but once DLC was worn out completely, wear of the piston ring was accelerated and its life became shorter than piston ring without DLC. In this research, we designed reciprocating test apparatus that operates at much higher velocity range, and characterized the frictional materials of the piston ring and sleeve and the DLC as a protective film, a vapor phase epitaxy (VPE) was actively used as a means to form certain level of convex and concave shape on its surface.

In a previous study by the authors, austenite (γ phase) formed on the topmost of pulleys after long term operation of continuously variable transmission (CVT) [1]. In general, martensite arising from heat treatment forms on the surface of pulleys and gears. Therefore, the sliding surface has a body-centered cubic (BCC) metal structure, and transformation into and existence of austenite (γ phase) is difficult unless there is a thermal history exceeding the eutectoid point. For the verification of that possibility, it was crucial to obtain temperature variation on the sliding surface. The major problem for such measurements was rotation of parts inside an operating CVT. In this study, uniquely developed measurement system enabled non-contact temperature measurement near the contact portion. Results were substituted to heat conduction equation to predict the temperature at the exact contact portion.