Valvetrain motion measurements in firing conditions by Laser Doppler Vibrometer

A methodology for the measurement of the valve kinematics in a high performance IC engine in firing condition is described in this paper. The method is based on the use of an In-plane Laser Doppler Vibrometer pointing on the valve stem through a transparent window on the engine inlet duct. The main advantages and drawbacks of the technique are discussed through the paper as well as guidelines for proper test settings. Results obtained are illustrated, they highlighting the potentials of the proposed technique to monitor valvetrain motion in operating conditions.