OIL FILM THICKNESS INSPECTION METHOD

摘要

PROBLEM TO BE SOLVED: To provide an oil film thickness inspection method allowing decision of whether or not a state of an oil film formed between a cylinder liner and a piston ring is within a sound range without applying machining to the cylinder liner.SOLUTION: An oil film observation method includes: an output process of outputting an ultrasonic wave to the inner wall face side of a cylinder liner 50 from a sensor part 12 of an ultrasonic sensor equipped on the outer wall face of the cylinder liner 50; a detection process of detecting a reflection wave of the ultrasonic wave outputted by the ultrasonic sensor; and a determination process of comparing an amplitude obtained by receiving the reflection wave and a reference value of a previously measured reflection wave and determining whether or not an amplitude difference between two sides is within a range of a threshold value.