Reducing Valve $—$ Pressure reducing valve

The Reducing Valve component describes a pressure reducing valve. The flow at port A depends on the pressure at port A (${\mathrm{port}}_{A}.p$). The commanded pressure is given by parameter ${p}_{\mathrm{nominal}}$. If the pressure is very low the valve is completely open from P to A; if it is much higher than the commanded value the valve is completely open from A to T. Between (${p}_{\mathrm{nominal}}-{p}_{\mathrm{work}}$) and (${p}_{\mathrm{nominal}}+{p}_{\mathrm{work}}$) the valve is in the working range.

 ${p}_{A}$ is lower than ${p}_{\mathrm{nominal}}-{p}_{\mathrm{work}}$ Passage P $\to$ A wide open. Flow rate from P $\to$ A: $q=\left({p}_{P}-{p}_{A}\right){G}_{\mathrm{PA}}$. ${p}_{A}$ is between ${p}_{\mathrm{nominal}}-{p}_{\mathrm{work}}$ and ${p}_{\mathrm{nominal}}$ Working range. Flow from P $\to$ A. ${p}_{A}$ is between ${p}_{\mathrm{nominal}}$ and ${p}_{\mathrm{nominal}}+{p}_{\mathrm{work}}$ Working range. Flow from A $\to$ T. ${p}_{A}$ is higher than ${p}_{\mathrm{nominal}}+{p}_{\mathrm{work}}$ Passage A $\to$ T wide open. Flow rate from A $\to$ T: $q=\left({p}_{A}-{p}_{T}\right){G}_{\mathrm{AT}}$.

The mass and flow forces are not included.

Use the modifier(s)

VolumeA(port_A(p(start=1e5,fixed=true)))

and/or

VolumeP(port_A(p(start=1e5,fixed=true)))

and/or

VolumeT(port_A(p(start=1e5,fixed=true)))

to set the initial condition(s) for the pressure of the lumped volume(s) $\left[\mathrm{Pa}\right]$.

Events

There is a new boolean reduceEvents (selected by default) in the Advanced section under the Properties tab ( ). Selecting reduceEvents lets the model use noEvents(expr) to generate fewer events for boolean expressions that should not generate events. In some cases the solver might reduce the stepsize too much and generate a lot of steps. If this happens, try clearing reduceEvents.

Variables

 Name Value Units Description Modelica ID ${V}_{T}$ VolumeT ${V}_{P}$ VolumeP ${V}_{A}$ VolumeA ${p}_{A\left(\mathrm{summary}\right)}$ ${p}_{A}$ $\mathrm{Pa}$ Pressure at port A summary_pA ${p}_{P\left(\mathrm{summary}\right)}$ ${p}_{P}$ $\mathrm{Pa}$ Pressure at port P summary_pP ${p}_{T\left(\mathrm{summary}\right)}$ ${p}_{T}$ $\mathrm{Pa}$ Pressure at port T summary_pT ${\mathrm{Δp}}_{\mathrm{PA}\left(\mathrm{summary}\right)}$ ${p}_{P}-{p}_{A}$ $\mathrm{Pa}$ Pressure drop summary_dp_PA ${\mathrm{Δp}}_{\mathrm{AT}\left(\mathrm{summary}\right)}$ ${p}_{A}-{p}_{T}$ $\mathrm{Pa}$ Pressure drop summary_dp_AT $\mathrm{reducingValve}$ reducingValve ${q}_{\mathrm{PA}\left(\mathrm{summary}\right)}$ $\mathrm{reducingValve.qPA}$ $\frac{{m}^{3}}{s}$ Flow rate flowing port_P to port_A summary_qPA ${q}_{\mathrm{AT}\left(\mathrm{summary}\right)}$ $\mathrm{reducingValve.qAT}$ $\frac{{m}^{3}}{s}$ Flow rate flowing port_A to port_T summary_qAT

Connections

 Name Description Modelica ID ${\mathrm{port}}_{P}$ Hydraulic port where oil enters the component port_P ${\mathrm{port}}_{T}$ Hydraulic port where oil enters the component port_T ${\mathrm{port}}_{A}$ Hydraulic port where oil leaves the component port_A $\mathrm{oil}$ oil

Parameters

General Parameters

 Name Default Units Description Modelica ID use volume A $\mathrm{true}$ If true, a volume is present at port_A useVolumeA use volume P $\mathrm{true}$ If true, a volume is present at port_P useVolumeP use volume T $\mathrm{true}$ If true, a volume is present at port_T useVolumeT ${V}_{A}$ ${10}^{-6}$ ${m}^{3}$ Geometric volume at port A volumeA ${V}_{P}$ ${10}^{-6}$ ${m}^{3}$ Geometric volume at port P volumeP ${V}_{T}$ ${10}^{-6}$ ${m}^{3}$ Geometric volume at port T volumeT ${\mathrm{ΔT}}_{\mathrm{system}}$ $0$ $K$ Temperature offset from system temperature dT_system ${p}_{\mathrm{nominal}}$ ${10}^{7}$ $\mathrm{Pa}$ Nominal pressure pnominal ${p}_{\mathrm{work}}$ $5.·{10}^{5}$ $\mathrm{Pa}$ Working range pwork ${G}_{\mathrm{PA}}$ $1.6·{10}^{-9}$ $\frac{{m}^{3}}{s\mathrm{Pa}}$ Conductance of wide open valve from P $\to$ A GPA ${G}_{\mathrm{AT}}$ $1.6·{10}^{-9}$ $\frac{{m}^{3}}{s\mathrm{Pa}}$ Conductance of wide open valve from A $\to$ T GAT

 Name Default Units Description Modelica ID reduce events $\mathrm{true}$ If true, generate less events reduceEvents