Approximation of IC Engine Valve Acceleration from Proximity Probe Displacement Data

This study utilizes an eddy current proximity probe to approximate the acceleration of a valve in a SOHC valve train. Several techniques are discussed for extrapolating acceleration data from displacement data through numerical differentiation. The data were compared to acceleration data as measured by an accelerometer mounted on the valve face. It was found that valve train acceleration behavior can be reasonably approximated using displacement data as measured by a proximity probe when differentiated using a three-point, Lagrangian interpolation. But the frequency response of the proximity probe is severely restricted by the limitations of the measurement and data collection instrumentation, the limitations of the differentiation method and the continuity of the base measured data.