Abstract

The swash-plate in a variable displacement pump experiences very large forces and moments that try to dislocate its position and therefore a large device is required for adequate control. In this paper, the dynamics of an alternative pump design using an indexing valve plate to position the swash-plate are reported. The indexing valve plate design is aimed at controlling pressure transition for a piston, which is moving from a high-pressure port to a low-pressure port and back. In this paper, the governing equations for the pump are derived and the detailed open-loop and parametric studies, which are necessary for understanding the overall dynamic characteristics of the pump, are reported. Also, full nonlinear and simplified modelling approaches for the system are compared.

Keywords: swash-plate, axial piston pump, indexing valve plate, pressure carry-over