MapleSim Hydraulics Library from Modelon
DCV_4_3_B Directional Control Valve with firstorder spool dynamics, a 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 DCV_4_3_B component describes a directional control valve with firstorder spool dynamics, a spool with 4 ports, and 3 stable positions. When it is in the middle position, ports A, B and T are connected and port P is closed.
The laminar/turbulent flow through the valve is modeled as flow through orifices without cavitation. The commanded opening of the valve is input at or , respectively.
The parameter qnom gives the nominal flow rate of the fully opened flow path at the pressure drop .
For example, the maximum diameter for the flow path from P to B is given by :
There is leakage flow modeled when the respective flow path is nominally closed. The position of the spool is modeled as a firstorder system.
Input signals: and .
When and , the left square of the valve icon describes the flow paths.
When and , the right square of the valve icon describes the flow paths.
Otherwise, the middle square describes the flow paths.
Intermediate positions and the respective connections are modeled and shown below. (See DCV_4_3_X for general information on valve diagrams.)
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. The effect can be modeled by the parameters P_max and coeff_P. Specify the maximum hydraulic power in (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).
The movement of the spool is described by a firstorder system. This is appropriate for valves that are directly actuated by a spool. The times to shift from the neutral position to an end position () may be different than the time to shift to the neutral position ().
Use the modifier(s)
VolumeA(port_A(p(start=1e5,fixed=true)))
and/or
VolumeB(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) .
Events
There is a new boolean reduceEvents (selected by default) in the Parameters 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.

Variables


Name

Value

Units

Description

Modelica ID




Pressure at port A

summary_pA




Pressure at port B

summary_pB




Pressure at port P

summary_pP




Pressure at port T

summary_pT


[1]


Pressure drop

summary_dp_PA


[2]


Pressure drop

summary_dp_PB


[3]


Pressure drop

summary_dp_AT


[4]


Pressure drop

summary_dp_BT





VolumeA





VolumeB





VolumeP





coil





spool_4_3





VolumeT




Flow rate flowing port_P to port_A

summary_qPA




Flow rate flowing port_P to port_B

summary_qPB




Flow rate flowing port_A to port_T

summary_qAT




Flow rate flowing port_B to port_T

summary_qBT



[1]
[2]
[3]
[4]


Connections


Name

Description

Modelica ID


Port A, one of valve connections to actuator or motor

port_A


Port B, one of valve connections to actuator or motor

port_B


Port P, where oil enters the component from the pump

port_P


Port T, where oil flows to the tank

port_T


Command signal for valve

commandB


Command signal for valve

commandA



oil





Parameters



General Parameters


Name

Default

Units

Description

Modelica ID

use volume A



If true, a volume is present at port_A

useVolumeA

use volume B



If true, a volume is present at port_B

useVolumeB

use volume P



If true, a volume is present at port_P

useVolumeP

use volume T



If true, a volume is present at port_T

useVolumeT




Geometric volume at port A

volumeA




Geometric volume at port B

volumeB




Geometric volume at port P

volumeP




Geometric volume at port T

volumeT




Temperature offset from system temperature

dT_system





Advanced Parameters


Name

Default

Units

Description

Modelica ID

reduce events



If true, reduce event generation

reduceEvents





Dynamic Parameters


Name

Default

Units

Description

Modelica ID




Switching time to open valve 95 %

tau_opening




Switching time to close valve 95 %

tau_closing





Flow Parameters


Name

Default

Units

Description

Modelica ID




Pressure drop at nominal flow rate qnom

dpnom




Nominal flow rate from P > A

qnom_P_A




Nominal flow rate from P > B

qnom_P_B




Nominal flow rate from A > T

qnom_A_T




Nominal flow rate from B > T

qnom_B_T




Nominal flow rate from A > B

qnom_A_B




Max. hydraulic power

P_max




Influence of hydraulic power on flow rate

coeff_P




Laminar part of orifice model

k1




Turbulent part of orifice model,

k2





Spool Geometry Parameters


Name

Default

Units

Description

Modelica ID




Diameter of equivalent orifice to model leakage of closed valve

dleak





