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3-Way Directional Valve (IL)

3-way flow control valve in an isothermal system

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  • Simscape / Fluids / Isothermal Liquid / Valves & Orifices / Directional Control Valves

  • 3-Way Directional Valve (IL) block

Description

The 3-Way Directional Valve (IL) block models a valve with three openings in an isothermal liquid network, typically between an actuator, pump, and tank. The valve operation is controlled by a single spool displaced according to the signal at port S. You can set the baseline configuration of your valve by specifying the orifices that are open when the spool moves in the positive direction and negative directions in the Positive spool position open connections and Negative spool position open connections parameters, respectively.

You can set the model for valve opening in the Orifice parameterization parameter as a linear relationship or function of user-provided data, which can be applied to one or all flow paths in the valve.

Example Valve Configuration

In this configuration, Positive spool position open connections is set to A-T only. When the signal at port S moves the spool to a positive position, the path between ports A and T is open to flow. The paths between ports P and A and between ports P and T are closed:

In this configuration, Negative spool position open connections is set to P-A only. When the signal at port S moves the spool to a negative position, the path between ports P and A is open to flow and the paths between ports T and A and between ports P and T are closed:

You can open the path between ports P and T by setting either Positive spool position open connections or Negative spool position open connections to P-T only or P-A, A-T, and P-T.

A flow path can be open in either the positive or negative spool positions, but not both.

Valve Orifice Parameterizations

The Orifice parameterization sets the method for calculating the valve open area. The calculations are based either on the orifice parameters or tabulated data sets specified in the Model Parameterization tab. The block uses the same data for all flow paths if Area characteristics is set to Identical for all flow paths; otherwise, individual values are applied in the Different for all flow paths setting. The orifice parameterizations are:

  • Linear - area vs. spool travel

    The opening area is a linear function of the spool travel distance and the signal received at port S:

    Aorifice=(AmaxAleak)ΔSmaxΔS+Aleak,

    where:

    • Amax is the Maximum orifice area.

    • Aleak is the Leakage area.

    • ΔSmax is the Spool travel between closed and open orifice.

    • ΔS is the spool travel distance. For flow paths that are open in the positive position:

      ΔS=Sorifice_max+ΔSmax+S,

      and for flow paths that are open in the negative position:

      ΔS=Sorifice_max+ΔSmaxS,

      where Sorifice_max is the Spool position at maximum orifice area.

  • Tabulated data - Area vs. spool travel

    Provide spool travel vectors for your system or for individual flow paths between ports P and A and ports A and T. This data will be used to calculate the relationship between the orifice opening area and spool travel distance. Interpolation is used to determine the opening area between given data points. Aleak and Amax are the first and last parameters of the Opening area vector, respectively.

  • Tabulated data - Volumetric flow rate vs. spool travel and pressure drop

    Provide spool travel and pressure drop vectors. The volumetric flow rate is calculated based on the relationship between pressure change and the spool travel distance. Interpolation is used to determine flow rate between given data points. The mass flow rate is the product of the volumetric flow rate and the local density.

Numerically-Smoothed Valve Area in the Linear Parameterization

When the valve is in a near-open or near-closed position in the linear parameterization, you can maintain numerical robustness in your simulation by adjusting the block Smoothing factor. A smoothing function is applied to all calculated areas, but primarily influences the simulation at the extremes of the valve area.

The normalized valve area is calculated as:

A^=(AorificeAleak)(AmaxAleak).

The Smoothing factor, s, is applied to the normalized area:

A^smoothed=12+12A^2+(s4)212(A^1)2+(s4)2.

The smoothed valve area is:

Asmoothed=A^smoothed(AmaxAleak)+Aleak.

Visualize Orifice Openings

To visualize spool offsets and displacement, right-click on the block and select Fluids > Plot Valve Characteristics. The plot shows the orifices selected in the Valve Configuration tab settings. The axes are set by the orifice parameterization selection and are either:

  • Orifice Area vs. Spool Position

  • Volumetric Flow Rate vs. Spool Position, queried at a specific pressure differential

Each time you modify the block settings, click Apply at the bottom of the dialog box, then click Reload Data on the figure window.

The image below shows the valve default configuration. On the Valve Configuration tab:

  • Positive spool position open connections is set to P-A only.

  • Negative spool position open connections is set to A-T only.

All other spool positions are at the default values.

Example Spool Position Visualization

Faulty Behavior

When faults are enabled, the valve open area becomes stuck at a specified spool position in response to one of these triggers:

  • Simulation time — Faulting occurs at a specified time.

  • Simulation behavior — Faulting occurs in response to an external trigger. This exposes port Tr.

Three fault options are available in the Spool position when faulted parameter:

  • Positive — The spool position freezes in the positive position, opening the Positive spool position open connections flow paths to their maximum value. The flow paths that are only open in the Negative spool position open connections and Neutral spool position open connections are closed.

  • Negative — The spool position freezes in the negative position, opening the Negative spool position open connections flow paths to their maximum value. The flow paths that are only open in the Positive spool position open connections and Neutral spool position open connections are closed.

  • Maintain last value — The valve freezes at the spool position when the trigger occurs.

Due to numerical smoothing at the extremes of the valve area, in the linear parameterization, the minimum area applied is larger than the Leakage area, and the maximum is smaller than the Maximum orifice area, in proportion to the Smoothing factor value.

Once triggered, the valve remains at the faulted area for the rest of the simulation.

Predefined Parameterization

Pre-parameterization of the 3-Way Directional Valve (IL) block with manufacturer data is available. This data allows you to model a specific supplier component.

To load a predefined parameterization,

  1. Click the "Select a predefined parameterization" hyperlink in the 3-Way Directional Valve (IL) block dialog description.

  2. Select a part from the drop-down menu and click Update block with selected part.

  3. If you change any parameter settings after loading a parameterization, you can check your changes by clicking Compare block settings with selected part. Any difference in settings between the block and pre-defined parameterization will display in the MATLAB command window.

Note that it is not possible to set different values for the same orifice for both positive and negative displacement of the control member. Additionally, the opening area is mirrored around the neutral position.

Note

Predefined parameterizations of Simscape components use available data sources for supplying parameter values. Engineering judgement and simplifying assumptions are used to fill in for missing data. As a result, deviations between simulated and actual physical behavior should be expected. To ensure requisite accuracy, you should validate simulated behavior against experimental data and refine component models as necessary.

Assumptions

  • Fluid inertia is ignored.

  • Spool loading due to inertial, spring, and other forces is ignored.

  • All valve orifices are assumed to be identical in size unless otherwise specified.

Ports

Conserving

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Exit point of the valve.

Entry point to the valve.

Entry or exit point to the valve.

Input

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Spool position displacement in m, received as a physical signal. For flow paths that open in the positive spool position, a positive signal opens the orifice. For flow paths that open in the negative spool position, a negative signal opens the orifice.

Physical signal port for an external fault trigger. Triggering occurs when the value is greater than 0.5. There is no unit associated with the trigger value.

Dependencies

This port is visible when Enable faults is set to On and Fault trigger is set to External.

Parameters

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Model Parameterization

Flow paths open when the spool is in a positive position. This parameter sets the valve configuration and defines the direction of spool movement according to the signal received at port S.

Flow paths open when the spool moves in the negative direction. This parameter sets the valve configuration and defines the direction of spool movement according to the signal received at port S.

Applies uniform or individual flow equations for the valve orifice area. Identical for all flow paths uses the same orifice and spool geometries, flow rates, pressure, and area vectors for all valve orifices. When using Different for each flow path, different spool offsets and tabulated data are assigned to the orifices between ports P and A, ports A and T, and ports P and T. In both cases, ports A, P, and T have the same cross-sectional areas, discharge coefficients, and Reynolds numbers. The same Orifice parameterization is also applied to all flow paths.

Method of calculating the valve opening area. In the tabulated data parameterizations, you can provide your own valve area and spool travel data for nonlinear valve opening profiles, or you can provide data in terms of volumetric flow rate, spool travel, and pressure drop over the flow path.

Maximum distance of spool travel. This value provides an upper limit to calculations so that simulations do not return unphysical values.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths.

Largest open area during operation of valve.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths.

Cross-sectional area at the entry and exit ports A, P, and T. These areas are used in the pressure-flow rate equation that determines volumetric flow rate through the valve.

Sum of all gaps when the valve is in its fully closed position. Any area smaller than this value is maintained at the specified leakage area. This contributes to numerical stability by maintaining continuity in the flow.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths and Orifice parameterization to Linear - area vs. spool travel.

Correction factor that accounts for discharge losses in theoretical flows.

Upper Reynolds number limit for laminar flow through the valve.

Continuous smoothing factor that introduces a layer of gradual change based to the flow response when the valve is in near-open and near-closed positions. To increase the stability of your simulation in these regimes, set this parameter to a nonzero value less than one.

Select to account for pressure increase when fluid flows from a region of a smaller cross-sectional area to a region of larger cross-sectional area.

Vector of control member travel distances for the tabular parameterization of valve area. The vector elements must correspond one-to-one with the elements in the Orifice area vector parameter. The values are listed in ascending order and the first element must be 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths and Orifice parameterization to Tabulated data - Area vs. spool travel.

Vector of opening areas for the tabular parameterization of valve opening area. The vector elements must correspond one-to-one with the elements in the Spool travel vector parameter. The elements are listed in ascending order and must be greater than 0.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths and Opening parameterization to Tabulated data - Area vs. spool travel.

Vector of control member travel distances for tabular parametrization of volumetric flow rate. The spool travel vector forms an independent axis with the Pressure drop vector, dp parameter for the 3-D dependent Volumetric flow rate table, q(ds,dp) parameter. A positive displacement corresponds to valve opening. The values are listed in ascending order and the first element must be 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths and Orifice parameterization to Volumetric flow rate vs. spool travel and pressure drop.

Vector of pressure drop values for tabular parametrization of volumetric flow rate. The pressure drop vector forms an independent axis with the Spool travel vector, s parameter for the 3-D dependent Volumetric flow rate table, q(ds,dp) parameter. The values are listed in ascending order and must be greater than 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths and Orifice parameterization to Volumetric flow rate vs. spool travel and pressure drop.

M-by-N matrix of volumetric flow rates based on independent values of pressure drop and spool travel distance. M and N are the sizes of the corresponding vectors:

  • M is the number of elements in the Pressure drop vector, dp parameter.

  • N is the number of elements in the Spool travel vector, ds parameter.

Dependencies

To enable this parameter, set Area characteristics to Identical for all flow paths and Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

P-A Orifice

Initial orifice opening distance between ports P and A. The default represents a zero-lapped system. A positive, nonzero value represents an underlapped, or partially open, system. A negative, nonzero value represents an overlapped system, where the valve remains closed over a range of control member displacements.

Maximum distance of spool travel for the orifice between ports P and A. This value provides an upper limit to calculations so that simulations do not return unphysical values.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path.

Cross-sectional area of the orifice between ports P and A in its fully open position.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Linear - area vs. spool travel.

Vector of control member travel distances for the tabular parameterization of valve area. The vector elements must correspond one-to-one with the elements in the P-A orifice area vector parameter. The values are listed in ascending order and the first element must be 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Area vs. spool travel.

Vector of opening areas for the tabular parameterization of valve opening area. The vector elements must correspond one-to-one with the elements in the P-A orifice spool travel vector parameter. The elements are listed in ascending order and must be greater than 0.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Opening parameterization to Tabulated data - Area vs. spool travel.

Vector of control member travel distances for tabular parametrization of volumetric flow rate. The spool travel vector forms an independent axis with the P-A orifice pressure drop vector, dp parameter for the 3-D dependent P-A orifice volumetric flow rate table, q(s,dp) parameter. A positive displacement corresponds to valve opening. The values are listed in ascending order and the first element must be 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

Vector of pressure drop values for tabular parametrization of volumetric flow rate. The pressure drop vector forms an independent axis with the P-A orifice spool travel vector, s parameter for the 3-D dependent P-A orifice volumetric flow rate table, q(s,dp) parameter. The values are listed in ascending order and must be greater than 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

M-by-N matrix of volumetric flow rates based on independent values of pressure drop and spool travel distance. M and N are the sizes of the corresponding vectors:

  • M is the number of elements in the P-A orifice pressure drop vector, dp parameter.

  • N is the number of elements in the P-A orifice spool travel vector, s parameter.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

A-T Orifice

Initial orifice opening distance between ports A and T. The default represents a zero-lapped system. A positive, nonzero value represents an underlapped, or partially-open, system. A negative, nonzero value represents an overlapped system, where the valve remains closed over a range of control member displacements.

Maximum distance of spool travel for the orifice between ports A and T. This value provides an upper limit to calculations so that simulations do not return unphysical values.

Dependencies

To enable this parameter, set Area characteristics type to Different for each flow path.

Cross-sectional area of the orifice between ports A and T in its fully open position.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Linear - area vs. spool travel.

Vector of control member travel distances for the tabular parameterization of valve area. The vector elements must correspond one-to-one with the elements in the A-T orifice area vector parameter. The values are listed in ascending order and the first element must be 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Area vs. spool travel.

Vector of opening areas for the tabular parameterization of valve opening area. The vector elements must correspond one-to-one with the elements in the A-T orifice spool travel vector parameter. The elements are listed in ascending order and must be greater than 0.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Opening parameterization to Tabulated data - Area vs. spool travel.

Vector of control member travel distances for tabular parametrization of volumetric flow rate. The spool travel vector forms an independent axis with the A-T orifice pressure drop vector, dp parameter for the 3-D dependent A-T orifice volumetric flow rate table, q(ds,dp) parameter. A positive displacement corresponds to valve opening. The values are listed in ascending order and the first element must be 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

Vector of pressure drop values for tabular parametrization of volumetric flow rate. The pressure drop vector forms an independent axis with the A-T orifice spool travel vector, s parameter for the 3-D dependent A-T orifice volumetric flow rate table, q(ds,dp) parameter. The values are listed in ascending order and must be greater than 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

M-by-N matrix of volumetric flow rates based on independent values of pressure drop and spool travel distance. M and N are the sizes of the corresponding vectors:

  • M is the number of elements in the A-T orifice pressure drop vector, dp parameter.

  • N is the number of elements in the A-T orifice spool travel vector, s parameter.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

P-T Orifice

Initial orifice opening distance between ports P and T. The default represents a zero-lapped system. A positive, nonzero value represents an underlapped, or partially-open, system. A negative, nonzero value represents an overlapped system, where the valve remains closed over a range of control member displacements.

Maximum distance of spool travel for the orifice between ports P and T. This value provides an upper limit to calculations so that simulations do not return unphysical values.

Dependencies

To enable this parameter, set Area characteristics type to Different for each flow path.

Cross-sectional area of the orifice between ports P and T in its fully open position.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Linear - area vs. spool travel.

Vector of control member travel distances for the tabular parameterization of valve area. The vector elements must correspond one-to-one with the elements in the P-T orifice area vector parameter. The values are listed in ascending order and the first element must be 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Area vs. spool travel.

Vector of opening areas for the tabular parameterization of valve opening area. The vector elements must correspond one-to-one with the elements in the P-T orifice spool travel vector parameter. The elements are listed in ascending order and must be greater than 0.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Opening parameterization to Tabulated data - Area vs. spool travel.

Vector of control member travel distances for tabular parametrization of volumetric flow rate. The spool travel vector forms an independent axis with the P-T orifice pressure drop vector, dp parameter for the 3-D dependent P-T orifice volumetric flow rate table, q(ds,dp) parameter. A positive displacement corresponds to valve opening. The values are listed in ascending order and the first element must be 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

Vector of pressure drop values for tabular parametrization of volumetric flow rate. The pressure drop vector forms an independent axis with the P-T orifice spool travel vector, ds parameter for the 3-D dependent P-T orifice volumetric flow rate table, q(ds,dp) parameter. The values are listed in ascending order and must be greater than 0. Linear interpolation is employed between table data points.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

M-by-N matrix of volumetric flow rates based on independent values of pressure drop and spool travel distance. M and N are the sizes of the corresponding vectors:

  • M is the number of elements in the P-T orifice pressure drop vector, dp parameter.

  • N is the number of elements in the P-T orifice spool travel vector, ds parameter.

Dependencies

To enable this parameter, set Area characteristics to Different for each flow path and Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

Faults

Enable externally or temporally triggered faults. When faulting occurs, the valve area normally set by the opening parameterization will be set to the value specified in the Spool position when faulted parameter.

Sets the faulted valve spool position. You can choose for the valve to seize when the spool is in the positive position, negative position, or at the position when faulting is triggered.

Dependencies

To enable this parameter, set Enable faults to On.

Whether a fault trigger occurs due to an external event or at a specified time.

When set to External, port Tr is enabled. A physical signal at port Tr that is greater than 0.5 triggers faulting.

When set to Temporal, when the Simulation time for fault event is reached, the valve area will be set to the value specified in the Spool position when faulted parameter.

Dependencies

To enable this parameter, set Enable faults to On.

When the Simulation time for fault event is reached, the valve area is set to the value specified in the Spool position when faulted parameter.

Dependencies

To enable this parameter, set Enable faults to On and Fault trigger to Temporal.

Introduced in R2020a