Study of Valve Seat Landing Stiffness and Damping 2014-01-2873

As the key parameters, stiffness and damping coefficient significantly influence on dynamic simulation result, which is the mean method of valve train design. This research aims to investigate the relation between landing velocity (v_L), contact duration (Δt), contact force (F_N), friction force (F_K), loss of valve kinetic energy (ΔW_V) on the landing impact between valve and seat insert. Tests were carried out on Over-Head-Cam Valve-train (OHC). Firstly, valve and seat insert contact stiffness in static state was measured, nonlinear increasing of stiffness was observed, because of contact area changing with load. Secondly, valve and seat dynamic impact tests were carried out in different landing velocities. Based on valve contact model, contact force (F_N), friction force (F_K) and sliding distance (S_L) were got by test data. As the result, contact stiffness and damping coefficient in dynamic state were analyzed. Different with linear constant parameter assumption, contact stiffness and damping coefficient in dynamic state increase with landing velocity. Investigating of the stiffness and damping coefficient under the action of impact-sliding would help to gain better understanding of the impact mechanisms. And contact force (F_N) and sliding distance (S_L) can be used as edge-restraint condition in valve-train design.