VariableDisplacementPump

Description

Model of a pump with variable displacement volume and losses.

The main parameters of the pump are its maximum Displacement volume and the Rotational moment of inertia. The displacement volume can be adjusted by using the setpoint signal:

The losses are parameterised by providing volumetric and mechanical efficiencies Volumetric efficiency and Mechanical efficiency for a given operating point. The operating point is characterised by a reference pressure difference Reference pressure difference and a corresponding shaft speed Reference speed. Based on the entered values, the parameters of a laminar throttle (volumetric losses) and a linear damper (representing the mechanical losses) are determined automatically. Unlike the efficiencies, the parameters of these two elements typically do not vary significantly with the operating conditions.

The parameter Ratio external Leakage / total Leakage allows to split the leakage between internal and external leakage. A gear pump e. g. typically has no external leakage, Ratio external Leakage / total Leakage has to be set to 0. In contrast, a piston pump has a significant external leakage (0.5 < Ratio external Leakage / total Leakage <= 1).

minSuctionPressure takes into account that a pump requires a minimaum suction pressure for full flow. Below this pressure, the flow rate is reduced. In this model, the reduction is assumed to be simplified as a linear function of suction pressure in relation to minSuctionPressure.