Evaluation of Lubrication Characteristics between the Piston and Cylinder in Hydraulic Piston Pump and Motor.

Abstract

Numerical analysis is carried out in order to express the mixed lubrication characteristics between piston and cylinder in the swash-plate type piston pump and motor. The distributions of fluid film pressure and the contact force between piston and cylinder are calculated, and λ(the contact ratio)is obtained for both pump and motor strokes. The lubrication characteristic is expressed by the relationship between λ and S0(the ratio of dynamic pressure to static pressure). The validity of the numerical analysis is discussed through comparison with the experimental results reported so far by the present authors. It is shown that the lubrication characteristic between the piston and cylinder is expressed by the λ-S0 curve independent of the operating conditions such as the pressure or rotation speed.