Lubrication characteristics of external return spherical hinge pair of axial piston pump or motor under combined action of inclination and offset distance

Abstract

External return mechanism is a mechanical structure applied to axial piston pumps. To study its lubrication characteristics, the Reynolds equation applied to an external return spherical hinge pair was deduced based on the vector equation of relative-motion velocity of the external return spherical hinge pair under the influence of external swash plate inclination and offset distance. The results show that the total friction, axial leakage flow, and maximum value of the maximum oil-film pressure increase with increasing pump-shaft speed and decrease with increasing offset distance in one working cycle when the external-swash-plate inclination is constant. However, the varying offset distance has little effect on the axial leakage flow. The maximum value of the maximum oil-film pressure decreases with increasing external-swash-plate inclination and the total leakage flow increases with increasing external-swash-plate inclination in one working cycle when the offset distance is constant. It can be seen that the abovementioned parameters are important factors that affect the lubrication characteristics of external return spherical hinge pairs. Therefore, the complex effects of different coupling parameters should be comprehensively considered in the design of the external return mechanism.

Keywords

axial piston motor or pump / external return mechanism / external swash plate inclination / offset distance / lubrication performance

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