Accu1 $—$ Hydro-pneumatic accumulator (simple gas model)

The Accu1 component describes a hydro-pneumatic accumulator filled with an ideal gas and a valve at the inlet port. Oil flows into the accumulator if the pressure at port_A is higher than the gas pressure, pgas. A lower limit is given for the gas pressure, pgas, by the precharge pressure, pprecharge. When initializing, the gas pressure, pgasstart, must be equal to or greater than the gas pre-charge pressure, pprecharge. There is a check whether this condition is met. This model will be replaced by a new model next release.

Related Components

 Name Description Hydro-pneumatic accumulator with a refined model of the charge gas.

Variables

 Name Value Units Description Modelica ID ${p}_{A\left(\mathrm{summary}\right)}$ ${p}_{A}$ $\mathrm{Pa}$ Pressure at port A summary_pA $\mathrm{gasVolume}$ gasVolume $\mathrm{TWV}$ TWV ${\mathrm{PMeas}}_{1}$ PMeas1 ${\mathrm{PMeas}}_{2}$ PMeas2 $\mathrm{ValveLog}$ ValveLog

Connections

 Name Description Modelica ID $\mathrm{oil}$ oil ${\mathrm{port}}_{A}$ Port A, where oil flows into the component ($0, ${p}_{B}<{p}_{A}$ means $0<\mathrm{Δp}$) port_A

Parameters

General Parameters

 Name Default Units Description Modelica ID ${V}_{0}$ $0.001$ ${m}^{3}$ Nominal volume V0 ${p}_{\mathrm{precharge}}$ $5.·{10}^{6}$ $\mathrm{Pa}$ Gas pre-charge pressure pprecharge ${p}_{\mathrm{gas}\left(\mathrm{t0}\right)}$ $6.·{10}^{6}$ $\mathrm{Pa}$ Initial gas pressure (at t = 0) pgasstart

Oil Parameters

 Name Default Units Description Modelica ID ${V}_{A}$ ${10}^{-6}$ ${m}^{3}$ Geometric volume at port A of TwoWayValve volumeA ${V}_{B}$ ${10}^{-6}$ ${m}^{3}$ Geometric volume at port B of TwoWayValve volumeB

Valve Parameters

 Name Default Units Description Modelica ID $\mathrm{overlap}$ $0.02$ Overlap relative to max. displacement = 1 overlap ${q}_{\mathrm{nom}}$ $8.33·{10}^{-4}$ $\frac{{m}^{3}}{s}$ Nominal flow rate qnom ${\mathrm{Δp}}_{\mathrm{nom}}$ $3.5·{10}^{6}$ $\mathrm{Pa}$ Pressure drop at qnom dpnom ${d}_{\mathrm{leak}}$ $0$ $m$ Diameter of equivalent orifice to model leakage of closed valve dleak ${k}_{1}$ $10$ Laminar part of orifice model k1 ${k}_{2}$ $2$ Turbulent part, ${k}_{2}=\frac{1}{{C}_{d}^{2}}$ k2 ${\mathrm{\omega }}_{0}$ $500$ $\frac{\mathrm{rad}}{s}$ Natural frequency of spool omega0 $\mathrm{damp}$ $1$ Damping coefficient of spool damp