Influence of Hydraulic Valve Lash Adjusters on the Dynamic Behavior of Valve Trains

Hydraulic lash adjusters are standard construction units in modern valve trains. Nevertheless, due to the sensitivity of the lash adjusters a special knowledge of the correlation between the response and the vibration excitation of the entire valve train is required. An analysis of the lifter shortening behavior as well as the lifter stiffness was carried out utilizing measurements of the relative movement of the plunger to the housing of the lifter, the check-valve displacement, the force profiles in the system, and the valve lift. It was found that the lifter dynamics and resonance effects in the valve train have a considerable influence on the valve bounce velocity. The influence of the cam kinematics on the response of the entire system is demonstrated using the example of the valve bounce velocity.