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4-Way Ideal Valve

(To be removed) Hydraulic 4-way critically-centered valve

The Hydraulics (Isothermal) library will be removed in a future release. Use the Isothermal Liquid library instead. (since R2020a)

For more information on updating your models, see Upgrading Hydraulic Models to Use Isothermal Liquid Blocks.


Directional Valves

  • 4-Way Ideal Valve block


The 4-Way Ideal Valve block represents a 4-way critically-centered valve, where initial openings of all four variable orifices are equal to zero. This significantly simplifies the model of a 4-way directional valve and makes it especially suitable for real-time and HIL (hardware-in-the-loop) simulation, where such assumption is applicable.

The flow rate is computed with the equation:



qFlow rate
xValve displacement, xmax <= x <= xmax
bOrifice width, b = Amax / xmax
AmaxMaximum orifice area
xmaxValve maximum opening
CDFlow discharge coefficient
ρFluid density
pSPressure supply
pA,pBPressures at the load ports A and B, respectively

Connections A and B are conserving hydraulic ports associated with the valve load ports. Connections P and S are the physical signal input ports that provide supply pressure and valve displacement values, respectively.

Basic Assumptions and Limitations

  • The valve is of a critically-centered type, that is, all initial openings are equal to zero.

  • The return pressure is assumed to be very low and can be treated as a zero pressure.

  • All the orifices are assumed to have the same shape and size, that is, the valve is symmetrical.


Valve passage maximum area

Specify the area of a fully opened valve. The parameter value must be greater than zero. The default value is 5e-5 m^2.

Valve maximum opening

Specify the maximum displacement of the control member. The parameter value must be greater than zero. The default value is 0.005 m.

Flow discharge coefficient

Semi-empirical parameter for valve capacity characterization. Its value depends on the geometrical properties of the valve, and usually is provided in textbooks or manufacturer data sheets. The default value is 0.7.

Global Parameters

Parameter determined by the type of working fluid:

  • Fluid density

Use the Hydraulic Fluid block or the Custom Hydraulic Fluid block to specify the fluid properties.


The block has the following ports:


Hydraulic conserving port associated with the actuator connection port.


Hydraulic conserving port associated with the actuator connection port.


Physical signal port that controls the supply pressure.


Physical signal port that controls spool displacement.


The Closed-Loop Hydraulic Actuator Model for Real-Time Simulation example is an example of using this valve, along with other blocks optimized for real-time and HIL simulation.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2010a

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