|M.Sc Student||Shinkarenko Alexey|
|Subject||Improving Tribological Performance of Piston Rings by|
Partial Surface Texturing
|Department||Department of Mechanical Engineering||Supervisors||Professor Emeritus Izhak Etsion|
|Dr. Yuri Kligerman|
An analytical model of the friction between a piston ring and cylinder liner is developed to study the potential use of partial micro-surface texturing in the form of spherical micro-dimples to improve tribological properties of reciprocating components. The hydrodynamic pressure distribution in the time dependent clearance between the piston ring and cylinder liner is obtained from a simultaneous solution of the Reynolds equation for the incompressible viscous fluid and the piston ring equation of motion in the radial direction. The time behavior of the friction force is calculated from the shear stresses in the viscous fluid film during the piston ring reciprocation, and the time dependent clearance between the piston ring and the cylinder liner. The average friction force value over one operating cycle of the engine is evaluated from integration of the time dependent friction force. An extensive parametric investigation was performed to identify the main important parameters of the problem. The optimum parameters of the surface texturing such as the dimple depth, the texture area density and the textured portion of the nominal contact surface of the piston ring were evaluated. The advantage of the partial texturing over the full texturing in view of minimizing friction losses was demonstrated. A comparison between the analytical and experimental results was done for several crank angular velocities. The test results were obtained from the a piston/cylinder system that is modeled by two nominally flat surfaces simulating segments of two piston rings reciprocating relative to a flat that simulates the cylinder liner.