Piston rod seal and scraper ring interaction in hydraulic cylinders

Abstract

In this work the problem of hydrodynamic cooperation and the inter action of piston rod seals and scraper rings is treated. The theory used is an extention of the hydrodynamic theory for single-seal elements presented earlier by the author. This theory is in turn based on the inverse hydrodynamic theory. A computer program, SIMPROS, for simulation of the performance of different seal element combinations has been developed. The following data are input data to the program: data describing running conditions such as sealed pressure, fluid viscosity and piston rod velocity; data describing the geometry of the surroundings of the seal elements; the static pressure distribution in the two seal contacts. The program considers the possibilities of cavitation, starvation and pressure build-up, and the following results are presented after a program run: leakage flow and total frictional force; fluid film thickness distributions in the two seal contacts; “cavitation degrees” and pressures in the parallel clearances. The function of the program is demonstrated with a test example.