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MapleSim Hydraulics Library from Modelon

Spool_4_3_B  Spool with 4 ports and 3 stable positions; when in the middle position, ports  A, B, and T are connected and port P is closed

The Spool_4_3_B component describes the spool of a directional control valve with 4 ports and 3 stable positions. When in the middle position, ports A, B, and T connected and port  P is closed.

The laminar/turbulent flow through the valve is modeled as flow through orifices without cavitation. The opening of the valve is input at the port spoolposition (1spoolposition  1). The parameter qnom gives the nominal flow rate of the fully opened flow path at the pressure drop dpnom.

Amax=qnom12ρk2Δpnom

dmax=2Amaxπ

For example, the maximum diameter for the flow path from P to B is given by dmaxPB:

AmaxPB=qnomPB12ρk2Δpnom

dmaxPB=2AmaxPBπ

The diameter depends on the spool position as given in the figure below.

There is leakage flow modeled when the respective flow path is nominally closed.

Input signal: spoolposition.

When spoolposition=1, the left square of the valve icon describes the flow paths.

When spoolposition=0, the middle square of the valve icon describes the flow paths.

When spoolposition=1, the right square of the valve icon describes the flow paths.

Intermediate positions and their respective connections are modeled and shown below.

 

Figure Flow paths in the valve as a function of spool position. 1 means completely open, 0 means completely closed.

 

When the pump pressure and the flow rate are high, the unbalanced forces and flow forces acting on the spool are higher than the force generated by the solenoid and the valve is partially closed. This effect can be modeled by the parameters P_max and coeff_P. Specify the maximum hydraulic power in W (where the valve is still completely open) and use coeff_P to adjust the model to the manufacturer's data. When the specified hydraulic power is exceeded, a warning is printed in the log window (Mode Simulation / Simulation / Show Log).

Events

There is a new boolean reduceEvents (selected by default) in the Advanced section under the Inspector 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.

Connections

Name

Description

Modelica ID

portA

Port A, one of valve connections to actuator or motor

port_A

portB

Port B, one of valve connections to actuator or motor

port_B

portP

Port P, where oil enters the component from the pump

port_P

portT

Port T, where oil flows to the tank

port_T

spoolposition

Command signal for spool position

spool_position

oil

 

oil

Parameters

General Parameters

Name

Default

Units

Description

Modelica ID

flow path A to B

true

 

There is a spool position with flow from port A to B

flowPath_AB

flow path P to T

false

 

There is a spool position with flow from port P to T

flowPath_PT

ΔTsystem

0

K

Temperature offset from system temperature

dT_system

Advanced Parameters

Name

Default

Units

Description

Modelica ID

reduce events

true

 

If true, reduce event generation

reduceEvents

Flow Parameters

Name

Default

Units

Description

Modelica ID

use CheckFlow

true

 

True, if a warning should be printed to user

useCheckFlow

Δpnom

7.·105

Pa

Pressure drop at nominal flow rate qnom

dpnom

qnomPA

0.00158

m3s

Nominal flow rate from P -> A

qnom_P_A

qnomPB

qnomPA

m3s

Nominal flow rate from P -> B

qnom_P_B

qnomAT

qnomPA

m3s

Nominal flow rate from A -> T

qnom_A_T

qnomBT

qnomPA

m3s

Nominal flow rate from B -> T

qnom_B_T

qnomAB

qnomPA

m3s

Nominal flow rate from A -> B

qnom_A_B

Pmax

1.26·105

W

Max. hydraulic power

P_max

coeffP

10

 

Influence of hydraulic power on flow rate

coeff_P

k1

10

 

Laminar part of orifice model

k1

k2

2

 

Turbulent part of orifice model, k2=1Cd2

k2

Spool Geometry Parameters

Name

Default

Units

Description

Modelica ID

dleak

1.67·10-5

m

Diameter of equivalent orifice to model leakage of closed valve

dleak

See Also

DirectionalControl, MapleSim Hydraulics Library from Modelon Overview


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