 Counter Balance Valve - MapleSim Help

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Counter Balance Valve

Check valve and relief valve connected in parallel Description The Counter Balance Valve component is a check valve and a relief valve connected in parallel, which can be piloted internally, externally, or both internally and externally. When pressure at port A is greater than the pressure at port B, the check valve orifice area is assumed to be a piecewise linear function of the pressure difference between port A and port B. When pressure at port B is greater than the pressure at port A, the relief valve orifice area is assumed to be a piecewise linear function and will be affected by the pilot mode selected. Based on the orifice area, the pressure vs. flow rate relationship is calculated by the formulation used in the Orifice component.
 Optional Volumes The boolean parameters Use volume A and Use volume B, when true, add optional volumes ${V}_{A}$  and ${V}_{B}$ to ports A and B, respectively. See Port Volumes for details. If two orifices or valves are connected, enabling a volume at the common port reduces the the stiffness of the system and improves the solvability.
 Equations $q={q}_{A}-{q}_{{V}_{A}}$ ${p}_{\mathrm{tot}}=\left\{\begin{array}{cc}-{k}_{\mathrm{back}}{p}_{A}+{p}_{B}& \mathrm{mode}=\mathrm{Internal}\\ {k}_{\mathrm{pilot}}{p}_{C}-{k}_{\mathrm{back}}{p}_{A}& \mathrm{mode}=\mathrm{External}\\ {k}_{\mathrm{pilot}}{p}_{C}-{k}_{\mathrm{back}}{p}_{A}+{p}_{B}& \mathrm{otherwise}\end{array}$ $\left\{\begin{array}{cc}\left\{{p}_{C}=\mathrm{portC.p},\mathrm{portC.q}=0\right\}& \mathrm{mode}\ne \mathrm{Internal}\\ {p}_{C}=0& \mathrm{otherwise}\end{array}$ $\left\{\begin{array}{cc}\left\{{A}_{\mathrm{cs}}={A}_{i},{A}_{i}={A}_{t}\right\}& \mathrm{Exact}\\ \left\{{A}_{\mathrm{cs}}=\mathrm{min}\left({A}_{\mathrm{open}},\mathrm{max}\left({A}_{\mathrm{close}},{A}_{i}\right)\right),{t}_{c}\frac{\mathrm{d}{A}_{i}}{\mathrm{d}t}+{A}_{i}={A}_{t}\right\}& \mathrm{otherwise}\end{array}$ ${A}_{t}=\left\{\begin{array}{cc}\left\{\begin{array}{cc}{A}_{\mathrm{close}}& {p}_{\mathrm{tot}}<{p}_{\mathrm{close1}}\\ \left\{\begin{array}{cc}{A}_{\mathrm{close}}+\left({p}_{\mathrm{tot}}-{p}_{\mathrm{close1}}\right)\frac{{A}_{\mathrm{open1}}-{A}_{\mathrm{close}}}{{p}_{\mathrm{open1}}-{p}_{\mathrm{close1}}}& {p}_{\mathrm{tot}}<{p}_{\mathrm{open1}}\\ {A}_{\mathrm{open1}}& \mathrm{otherwise}\end{array}& \mathrm{otherwise}\end{array}& p<0\\ \left\{\begin{array}{cc}{A}_{\mathrm{close}}& p\le {p}_{\mathrm{close2}}\\ \left\{\begin{array}{cc}{A}_{\mathrm{close}}+\left(p-{p}_{\mathrm{close2}}\right)\frac{{A}_{\mathrm{open2}}-{A}_{\mathrm{close}}}{{p}_{\mathrm{open2}}-{p}_{\mathrm{close2}}}& p\le {p}_{\mathrm{open2}}\\ {A}_{\mathrm{open2}}& \mathrm{otherwise}\end{array}& \mathrm{otherwise}\end{array}& \mathrm{otherwise}\end{array}$ ${V}_{{f}_{A}}=\left\{\begin{array}{cc}{V}_{A}\left(1+\frac{{p}_{A}}{\mathrm{El}}\right)& \mathrm{useVolumeA}\\ 0& \mathrm{otherwise}\end{array}$ ${V}_{{f}_{B}}=\left\{\begin{array}{cc}{V}_{B}\left(1+\frac{{p}_{B}}{\mathrm{El}}\right)& \mathrm{useVolumeB}\\ 0& \mathrm{otherwise}\end{array}$ ${q}_{{V}_{A}}=\left\{\begin{array}{cc}\frac{\mathrm{d}{V}_{{f}_{A}}}{\mathrm{d}t}& \mathrm{useVolumeA}\\ 0& \mathrm{otherwise}\end{array}$ ${q}_{{V}_{B}}=\left\{\begin{array}{cc}\frac{\mathrm{d}{V}_{{f}_{B}}}{\mathrm{d}t}& \mathrm{useVolumeB}\\ 0& \mathrm{otherwise}\end{array}$ ${q}_{A}+{q}_{B}-{q}_{{V}_{A}}-{q}_{{V}_{B}}=0$

Variables

 Name Value Units Description Modelica ID $p$ Pressure across component $\mathrm{Pa}$ Pressure drop from A to B p $q$ Flow rate through component $\frac{{m}^{3}}{s}$ Flow rate from port A to port B q ${q}_{\mathrm{summary}}$ $q\mathrm{flowScaleSummary}$ $\frac{{m}^{3}}{s}$ Internal flow sensor q_summary ${\mathrm{dp}}_{\mathrm{summary}}$ $p\mathrm{pressScaleSummary}$ $\mathrm{Pa}$ Internal pressure difference sensor dp_summary

Connections

 Name Description Modelica ID $\mathrm{portA}$ Upstream hydraulic port portA $\mathrm{portB}$ Downstream hydraulic port portB $\mathrm{portC}$ Hydraulic port for external pilot portC

Parameters

General Parameters

 Name Default Units Description Modelica ID ${C}_{d}$ $\frac{7}{10}$ Flow-discharge coefficient Cd ${\mathrm{\Re }}_{\mathrm{Cr}}$ $12$ Reynolds number at critical flow ReCr

Check Valve Settings Parameters

 Name Default Units Description Modelica ID ${p}_{\mathrm{close}}$ $1.9·{10}^{4}$ $\mathrm{Pa}$ Pressure at which valve is fully closed ($A={A}_{\mathrm{close}}$) pclose2 ${p}_{\mathrm{open}}$ $2.05·{10}^{4}$ $\mathrm{Pa}$ Pressure at which valve is fully open ($A={A}_{\mathrm{open}}$) popen2 ${A}_{\mathrm{open}}$ $1·{10}^{-5}$ ${m}^{2}$ Valve area when fully open Aopen2

Leakage Parameters

 Name Default Units Description Modelica ID ${A}_{\mathrm{close}}$ $1·{10}^{-12}$ ${m}^{2}$ Valve area when closed (leakage) Aclose

Pilot Parameters

 Name Default Units Description Modelica ID $\mathrm{mode}$ Internal Pilot type mode

Pressure Ratios Parameters

 Name Default Units Description Modelica ID ${k}_{\mathrm{pilot}}$ $3$ Pilot ratio kp1 ${k}_{\mathrm{back}}$ $0$ Backpressure ratio kp2

Relief Settings Parameters

 Name Default Units Description Modelica ID ${p}_{\mathrm{close}}$ $1.9·{10}^{7}$ $\mathrm{Pa}$ Pressure at which valve is fully closed (A = Aclose) pclose1 ${p}_{\mathrm{open}}$ $2.05·{10}^{7}$ $\mathrm{Pa}$ Pressure at which valve is fully open (A = Aopen) popen1 ${A}_{\mathrm{open}}$ $1·{10}^{-5}$ ${m}^{2}$ Valve area when fully open Aopen1

Valve Dynamics Parameters

 Name Default Units Description Modelica ID $\mathrm{Exact}$ $\mathrm{false}$ When true (checked) a first-order dynamics is used for the valve area Exact ${t}_{c}$ $\frac{1}{10}$ $s$ Time constant tc

Volume Parameters

 Name Default Units Description Modelica ID Use volume A $\mathrm{false}$ When true a hydraulic volume chamber is added to portA useVolumeA ${V}_{A}$ $1·{10}^{-6}$ ${m}^{3}$ Volume of chamber A Va Use volume B $\mathrm{false}$ When true a hydraulic volume chamber is added to portB useVolumeB ${V}_{B}$ $1·{10}^{-6}$ ${m}^{3}$ Volume of chamber B Vb

For more information see Port Volumes.

 See Also