Counter Balance Valve - MapleSim Help

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Counter Balance Valve

Check valve and relief valve connected in parallel

 

Description

Optional Volumes

Equations

Variables

Connections

Parameters

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 VA  and VB to ports A and B, respectively. See Port Volumes for details.

If two orfices or valves are connected, enabling a volume at the common port reduces the the stiffness of the system and improves the solvability.

Equations

q=qAqVA

ptot={kbackpA+pBmode=InternalkpilotpCkbackpAmode=ExternalkpilotpCkbackpA+pBotherwise

{pC=portC.p,portC.q=0modeInternalpC=0otherwise

{Acs=Ai,Ai=AtExactAcs=minAopen,maxAclose,Ai,tcdAidt+Ai=Atotherwise

At&equals;{{Acloseptot<pclose1{Aclose&plus;ptotpclose1Aopen1Aclosepopen1pclose1ptot<popen1Aopen1otherwiseotherwisep<0{Acloseppclose2{Aclose&plus;ppclose2Aopen2Aclosepopen2pclose2ppopen2Aopen2otherwiseotherwiseotherwise

VfA&equals;{VA1&plus;pAEluseVolumeA0otherwise

VfB&equals;{VB1&plus;pBEluseVolumeB0otherwise

qVA&equals;{dVfAdtuseVolumeA0otherwise

qVB&equals;{dVfBdtuseVolumeB0otherwise

qA&plus;qBqVAqVB&equals;0

Variables

Name

Value

Units

Description

Modelica ID

p

Pressure across component

Pa

Pressure drop from A to B

p

q

Flow rate through component

m3s

Flow rate from port A to port B

q

qsummary

qflowScaleSummary

m3s

Internal flow sensor

q_summary

dpsummary

ppressScaleSummary

Pa

Internal pressure difference sensor

dp_summary

Connections

Name

Description

Modelica ID

portA

Upstream hydraulic port

portA

portB

Downstream hydraulic port

portB

portC

Hydraulic port for external pilot

portC

Parameters

General Parameters

Name

Default

Units

Description

Modelica ID

Cd

710

 

Flow-discharge coefficient

Cd

Cr

12

 

Reynolds number at critical flow

ReCr

Check Valve Settings Parameters

Name

Default

Units

Description

Modelica ID

pclose

1.9·104

Pa

Pressure at which valve is fully closed (A&equals;Aclose)

pclose2

popen

2.05·104

Pa

Pressure at which valve is fully open (A&equals;Aopen)

popen2

Aopen

1·10−5

m2

Valve area when fully open

Aopen2

Leakage Parameters

Name

Default

Units

Description

Modelica ID

Aclose

1·10−12

m2

Valve area when closed (leakage)

Aclose

Pilot Parameters

Name

Default

Units

Description

Modelica ID

mode

Internal

 

Pilot type

mode

Pressure Ratios Parameters

Name

Default

Units

Description

Modelica ID

kpilot

3

 

Pilot ratio

kp1

kback

0

 

Backpressure ratio

kp2

Relief Settings Parameters

Name

Default

Units

Description

Modelica ID

pclose

1.9·107

Pa

Pressure at which valve is fully closed (A = Aclose)

pclose1

popen

2.05·107

Pa

Pressure at which valve is fully open (A = Aopen)

popen1

Aopen

1·10−5

m2

Valve area when fully open

Aopen1

Valve Dynamics Parameters

Name

Default

Units

Description

Modelica ID

Exact

false

 

When true (checked) a first-order dynamics is used for the valve area

Exact

tc

110

s

Time constant

tc

Volume Parameters

Name

Default

Units

Description

Modelica ID

Use volume A

false

 

When true a hydraulic volume chamber is added to portA

useVolumeA

VA

1·10−6

m3

Volume of chamber A

Va

Use volume B

false

 

When true a hydraulic volume chamber is added to portB

useVolumeB

VB

1·10−6

m3

Volume of chamber B

Vb

For more information see Port Volumes.

See Also

Hydraulics Library

Valves