NVH is a necessary consideration in engine component development. The piston pin joint can be a significant contributor of mechanical noise in SI engines. Although there is literature on this subject, most of it is dealing with measurement using accelerometers for vibration analysis. This however does not indicate the fundamentals of the piston pin to connecting rod pin bore interaction mechanism. Limited research was found on this matter which prompted this investigation.
A measurement system was designed to determine the connecting rod small end bore clearance in real-time from the base and side of the pin bore. In this system, we applied a high precision displacement sensor to measure the pin motion, and a linkage was designed and fabricated to transfer the signal output out of the engine. This information was then correlated with accelerometer impact measurements to create a baseline for piston pin motion. Impacts were linked to the load reversal of the piston pin to connecting rod interface.
