A new measurement system and methodology has been developed which allows for direct measurement of the piston pin behavior of an internal combustion engine, particularly as it relates to pin joint ticking noise contributing to Noise Vibration and Harshness (NVH). Based on the measured dynamic of the piston pin during engine operation, the root cause of the pin joint ticking noise in this application was defined to be sticking of the pin at the end of the exhaust stroke which prevented pin lift. In order to better understand and mitigate this phenomenon, numerical simulation was conducted by means of Elasto Hydrodynamic Lubrication (EHL).
The output of this simulation showed that modifying the shape of the connecting rod pin bore by ovality has a significant effect on the pin motion and pin acceleration which could eliminate the pin joint tick noise. This improved pin bore shape was tested in the engine and confirmed to eliminate the pin joint ticking noise by manipulating the pin motion and disallowing piston pin sticking. Finally, an analysis of the newly developed methodology to root cause and solve pin joint ticking is compared to the prior methodology.
