A Development of Measurement System for Piston Ring Sliding Surface Pressure 2018-32-0022

The piston rings, the engine sliding parts, are required to further contribute on mechanical loss reduction in order to improve fuel efficiency. However, many cases of the abnormal combustion due to oil upward flow, as well as the increase in oil consumption have been reported. Therefore, elucidation of the mechanism of those phenomena is still an urgent task. It is widely known that the distribution of the sliding face pressure in between the piston ring and the cylinder bore largely influence the oil flow via the sliding face of the piston ring. However, there are many unknown aspects in this field. Therefore, verification of the sliding face pressure during the actual operation is necessary in order to elucidate the mechanism of oil consumption. The thin-film sensor, since it has little influence on shape, is widely used as a measurement method of the sliding face pressure between two different faces, however this method has never been applied to the piston ring in the past. Authors, through the examination of various film deposition methods, succeeded in forming the thin-film sensor with a total thickness of 4-5μm by the sputtering method on the sliding face of the piston ring. In addition, with regard to each device composing the measurement system, improvements are applied to obtain better S/N ratio, which enabled the establishment of the measurement system with extended measurable area towards lower pressure region. Furthermore, authors succeeded in measuring the piston ring sliding face pressure through the examination using the rig test device.