抄録
An application of ultrasonic technique is attempted for the purpose of measuring film thickness between moving surfaces. The measurement of film thickness is possible only by setting the ultrasonic probe to one of the friction surface, and the drilling for installing the probe like a measurement using a displacement sensor is not conducted. The ultrasonic wave emitted to the hydrodynamic lubrication interface is reflected multiple in oil film, and the echo height of reflected wave from the boundary is dependent on film thickness. For example, the thickness of oil film between cylinder and piston ring can be easily measured only by setting the small ultrasonic probe on the back of piston ring. On the other hand, the echo height under the mixed lubrication region is mainly dependent on the solid contact area. Therefore, the load share rate at the solid contact parts can be estimated from observed echo height.
