Means and method for varying margin pressure as a function of pump displacement in a pump with load sensing control

摘要

A pump system includes a variable fluid displacement pump having a pressure line which is connected to a pressure load and connected to a load sensing control. A variable orifice is located downstream from the load sensing control. The variable orifice is fluidly connected to the load sensing control in a servo pressure conduit such that the margin pressure varies proportionally with respect to the fluid displacement Of the pump. The variable orifice can take many different forms, including a variable cross sectional area gap between the housing and an elongated servo piston longitudinally slidable therein. A longitudinal slot having uniformly increasing depth along the length of the servo piston gives the servo piston a cross sectional area which varies along its length. Thus, a variable orifice results.