Three Way Flow Control $—$ Three way flow control valve

The Three Way Flow Control component describes a three way flow control valve (bypass type). The commanded flow rate is given by the input signal at $\mathrm{qCommand}$ [${m}^{3}$/$s$]. If the demanded flow rate is in the working range of the valve, the conductance of the valve is calculated such that the demanded flow rate is achieved with a minimum pressure at port A. The conductance of the flow control part of the valve is limited by GMax (that is, a wide open valve) and GMin (that is, a closed valve with leakage from A to B only). The conductance of the pressure control part of the valve is limited by GOpen (wide open valve) and GLeak (valve closed, leakage from A to T only). As no dynamic effects are modeled, the jump phenomenon does not occur.

Setting parameters

 ${\mathrm{Δp}}_{\mathrm{nom}}$ This parameter gives the nominal pressure differential from port_A to port_B if the valve is in the operating range. Typical values: 3-7e5 $\mathrm{Pa}$. GMax The maximum flow rate from A to B for a given ${\mathrm{Δp}}_{\mathrm{nom}}$ is given by: $\mathrm{qmax}=\mathrm{dpnom}\mathrm{GMax}$ This gives the nominal working range of the valve. GMin Conductance of closed series flow control valve (that is, leakage from A to B if commanded flow rate = 0). dpopen The relief valve is wide open if the pressure differential across that valve is higher than dpopen. GOpen The maximum flow rate from A to T where the relief valve is in the operating range is given by: $\mathrm{qmax_relief}=\mathrm{dpopen}\mathrm{GOpen}$ If the pump flow rate at port_A is greater than qmax_relief while commanded flow rate = 0, the pressure at port_A will be greater than dpopen. GLeak Conductance of closed relief valve (that is, leakage from A to T regardless of the commanded flow rate): $\mathrm{GLeak}\left(\mathrm{port_A}.p-\mathrm{port_B}.p\right)=\mathrm{q_leak_relief}$

The mass and flow forces are not included. Use the modifier(s)

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

and/or

VolumeB(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.

Related Components

 Name Description Serial flow control valve, restriction type

Variables

 Name Value Units Description Modelica ID ${V}_{A}$ VolumeA ${V}_{B}$ VolumeB ${V}_{T}$ VolumeT ${p}_{A\left(\mathrm{summary}\right)}$ ${p}_{A}$ $\mathrm{Pa}$ Pressure at port A summary_pA ${p}_{B\left(\mathrm{summary}\right)}$ ${p}_{B}$ $\mathrm{Pa}$ Pressure at port P summary_pB ${p}_{T\left(\mathrm{summary}\right)}$ ${p}_{T}$ $\mathrm{Pa}$ Pressure at port T summary_pT ${\mathrm{Δp}}_{\mathrm{AT}\left(\mathrm{summary}\right)}$ ${p}_{A}-{p}_{T}$ $\mathrm{Pa}$ Pressure drop summary_dp_AT ${\mathrm{Δp}}_{\mathrm{BT}\left(\mathrm{summary}\right)}$ ${p}_{B}-{p}_{T}$ $\mathrm{Pa}$ Pressure drop summary_dp_BT ${\mathrm{ReliefValveExtComNoStates}}_{1}$ ReliefValveExtComNoStates1 ${\mathrm{SfcExtCom}}_{1}$ SfcExtCom1 ${q}_{\mathrm{AB}\left(\mathrm{summary}\right)}$ $\mathrm{SfcExtCom1.q}$ $\frac{{m}^{3}}{s}$ Flow rate flowing port_P to port_A summary_qAB ${q}_{\mathrm{AT}\left(\mathrm{summary}\right)}$ [1] $\frac{{m}^{3}}{s}$ Flow rate flowing port_P to port_B summary_qAT

[1] $\mathrm{ReliefValveExtComNoStates1.q}$

Connections

 Name Description Modelica ID ${\mathrm{port}}_{A}$ port_A: oil mostly enters the element port_A ${\mathrm{port}}_{B}$ Hydraulic port where oil enters or leaves the element port_B ${\mathrm{port}}_{T}$ Hydraulic port where oil mostly leaves the element port_T $\mathrm{oil}$ oil ${q}_{\mathrm{Command}}$ Command signal for flow rate qCommand

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 B $\mathrm{true}$ If true, a volume is present at port_B useVolumeB 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 ${V}_{B}$ ${10}^{-6}$ ${m}^{3}$ Geometric volume at port B volumeB ${V}_{T}$ ${10}^{-6}$ ${m}^{3}$ Geometric volume at port T volumeT ${\mathrm{ΔT}}_{\mathrm{system}}$ $0$ $K$ Temperature offset from system temperature dT_system ${\mathrm{Δp}}_{\mathrm{nom}}$ $5.·{10}^{5}$ $\mathrm{Pa}$ Nominal pressure differential from A to B dpnom ${G}_{\mathrm{max}}$ $3.03·{10}^{-10}$ $\frac{{m}^{3}}{s\mathrm{Pa}}$ Conductance of wide open series flow control valve GMax ${G}_{\mathrm{min}}$ $3.03·{10}^{-16}$ $\frac{{m}^{3}}{s\mathrm{Pa}}$ Conductance of closed series flow control valve, i. e. leakage GMin ${\mathrm{Δp}}_{\mathrm{open}}$ $2.·{10}^{5}$ $\mathrm{Pa}$ Relief valve wide open if ${\mathrm{Δp}}_{\mathrm{open}}<\mathrm{Δp}$ dpopen ${G}_{\mathrm{open}}$ $1.67·{10}^{-9}$ $\frac{{m}^{3}}{s\mathrm{Pa}}$ Conductance of wide open relief valve GOpen ${G}_{\mathrm{leak}}$ $1.11·{10}^{-12}$ $\frac{{m}^{3}}{s\mathrm{Pa}}$ Conductance of closed relief valve, i. e. leakage GLeak

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