Study Of Valve Seat Wear Based On Energetic Approach

The performance and emission requirements of engine become more and more critical with therapid development of automotive industry, and all the components of the valve will be increasinglydemanding and durable. Valve train, which is one of the key components of the engine, plays animportant role in intake and exhaust system so that the fresh air is instead of the exhaust gas andengine can work best, and holds up the engine’s power performance, fuel economy and fatigue life.So, the research of valve and valve seat is always a key issue in valve train.In order to analyze the valve life and wear loss of valve seat, an energetic approach was usedto predict fatigue life and wear based on the dynamic experiment of valve train, furthermore, thecontact stiffness and landing damping were analyzed in this process.(1) Three different experiments about the stiffness have been conducted in this paper, whichwere about static stiffness of the static contact between the valve and valve seat, dynamic stiffnessduring valve seating, and the actual stiffness of valve train. This dynamic experiment was made upwith experiment designing, experimental test bed building, and acquisition system in this paper. Inthis process, the acceleration and velocity of the valve was measured, besides, the stress of rockerarm can be measured too.(2) The contact stiffness and landing damping were introduced respectively. A simulated valvelanding process was designed to analysis the external damping and internal damping during thisprocess. In addition, the damping is not fixed but rather changes with the impact closing velocity inexternal damping. Three different experiments about the stiffness have been conducted in this paper,which were about static stiffness of the static contact between the valve and valve seat, dynamicstiffness during valve seating, and the actual stiffness of valve train. Experimental results show thatthe valve seating process is a complicated nonlinear process, and the contact stiffness between thevalve and valve seat increase with the increment of seating velocity.(3) The HyperMesh was used to meshing in the element finite pre-process in the paper, andthen the mechanical load, thermal load and mechanical-thermal load was calculated by theABAQUS respectively. The result showed that the contact surface is the weakest part between thevalve and valve seat, where the stress is concentrated. Especially, the wear loss rate risessignificantly depending on the camshaft speed, and finally the valve seat will be broken.(4) In this paper, the energetic approach and he S-N curve were put forward, and then thefatigue life was calculated by S-N curve. Based on the wear of metals, the wear loss was analyzedand the wear amount of the valve seat was calculated further. The fatigue life and wear loss can match the theoretical prediction perfectly.