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

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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:

  $$A_{orifice}=\frac{\left(A_{\max }-A_{leak}\right)}{\Delta S_{\max }}\Delta S+A_{leak},$$

  where:

  • A_max is the Maximum orifice area.

  • A_leak is the Leakage area.

  • ΔS_max 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:

    $$\Delta S=S_{orifice\_\max }+\Delta S_{\max }+S,$$

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

    $$\Delta S=S_{orifice\_\max }+\Delta S_{\max }-S,$$

    where S_{orifice_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. A_leak and A_max 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:

$$\widehat{A}=\frac{\left(A_{orifice}-A_{leak}\right)}{\left(A_{\max }-A_{leak}\right)}.$$

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

$${\widehat{A}}_{smoothed}=\frac{1}{2}+\frac{1}{2}\sqrt{{\widehat{A}}_{}^2+{\left(\frac{s}{4}\right)}^2}-\frac{1}{2}\sqrt{{\left(\widehat{A}-1\right)}^2+{\left(\frac{s}{4}\right)}^2}.$$

The smoothed valve area is:

$$A_{smoothed}={\widehat{A}}_{smoothed}\left(A_{\max }-A_{leak}\right)+A_{leak}.$$

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

A — Liquid port

isothermal liquid

Exit point of the valve.

P — Liquid port

isothermal liquid

Entry point to the valve.

T — Liquid port

isothermal liquid

Entry or exit point to the valve.

Input

S — Control member displacement, m

physical signal

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.

Tr — External fault trigger

physical signal

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

Model Parameterization

Positive spool position open connections — Flow paths open when the spool is in a positive position

P-T only (default) | All closed | P-A, A-T, and P-T | P-A only | A-T only

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.

Negative spool position open connections — Flow paths open when the spool moves in the negative direction

P-A only (default) | All closed | P-A, A-T, and P-T | A-T only | P-T only

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.

Area characteristics — Flow equations for orifices

Identical for all flow paths (default) | Different for each flow path

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.

Orifice parameterization — Method of calculating opening area

Linear area vs. spool travel (default) | Tabulated data - Area vs. spool travel | Tabulated data - volumetric flow rate vs. spool travel and pressure drop

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.

Spool travel between closed and open orifice — Maximum spool stroke

0.005 m (default) | positive scalar

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.

Maximum orifice area — Maximum orifice opening area

1e-4 m^2 (default) | positive scalar

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 ports A, P and T — Area at valve entry or exit

inf m^2 (default) | positive scalar

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.

Leakage area — Gap area when in fully closed position

1e-10 m^2 (default) | positive scalar

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.

Discharge coefficient — Discharge coefficient

0.64 (default) | positive scalar

Correction factor that accounts for discharge losses in theoretical flows.

Critical Reynolds number — Upper Reynolds number limit for laminar flow

150 (default) | positive scalar

Upper Reynolds number limit for laminar flow through the valve.

Smoothing factor — Numerical smoothing factor

0.01 (default) | positive scalar in the range [0,1]

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.

Pressure recovery — Whether to account for pressure increase in area expansions

On (default) | Off

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.

Spool travel vector — Vector of valve opening distance

[0, .002, .004, .007, .017] m (default) | 1-byn vector

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.

Orifice area vector — Vector of valve opening areas

[1e-09, 2.0352e-07, 4.0736e-05, .00011438, .00034356] m^2 (default) | 1-byn vector

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.

Spool travel vector, ds — Vector of valve opening distances

[0, .002, .004, .007, .017] m (default) | 1-by-n vector

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.

Pressure drop vector, dp — Vector of valve pressure drop values

[.3, .5, .7] MPa (default) | 1-by-n vector

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.

Volumetric flow rate table, q(ds,dp) — Array of volumetric flow rates

[1.7e-05, 2e-05, 2.6e-05; .0035, .0045, .0053; .7, .9, 1.06; 1.96, 2.5, 3; 6, 7.7, 9.13] .* 1e-3 m^3/s (default) | M-by-N matrix

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

Spool position at maximum P-A orifice area — Spool offset at maximum area between ports P and A

2.5e-3 m (default) | scalar

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.

P-A spool travel between closed and open orifice — Maximum stroke for the spool between ports P and A

0.005 m (default) | positive scalar

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.

P-A maximum orifice area — Maximum area between ports P and A

1e-4 m^2 (default) | positive scalar

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.

P-A orifice spool travel vector — Vector of valve opening distance

[0, .002, .004, .007, .017] m (default) | 1-byn vector

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.

P-A orifice area vector — Vector of valve opening areas

[1e-09, 2.0352e-07, 4.0736e-05, .00011438, .00034356] m^2 (default) | 1-by-n vector

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.

P-A orifice spool travel vector, ds — Vector of valve opening distances

[0, .002, .004, .007, .017] m (default) | 1-by-n vector

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.

P-A orifice pressure drop vector, dp — Vector of pressure drop values over the valve

[.3, .5, .7] MPa (default) | 1-by-n vector

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.

P-A orifice volumetric flow rate table, q(ds,dp) — Vector of valve volumetric flow rates

[1.7e-05, 2e-05, 2.6e-05; .0035, .0045, .0053; .7, .9, 1.06; 1.96, 2.5, 3; 6, 7.7, 9.13] .* 1e-3 m^3/s (default) | M-by-N matrix

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

Spool position at maximum A-T orifice area — Spool offset at maximum area between ports A and T

5e-3 m (default) | scalar

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.

A-T spool travel between closed and open orifice — Maximum stroke for the spool between ports A and T

0.005 m (default) | positive scalar

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.

A-T maximum orifice area — Maximum area between ports A and T

1e-4 m^2 (default) | positive scalar

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.

A-T orifice spool travel vector — Vector of valve opening distances

[0, .002, .004, .007, .017] m (default) | 1-by-n vector

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.

A-T orifice area vector — Vector of valve opening areas

[1e-09, 2.0352e-07, 4.0736e-05, .00011438, .00034356] m^2 (default) | 1-by-n vector

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.

A-T orifice spool travel vector, ds — Vector of valve opening distances

[0, .002, .004, .007, .017] m (default) | 1-by-n vector

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.

A-T orifice pressure drop vector, dp — Vector of pressure drop values over the valve

[.3, .5, .7] MPa (default) | 1-by-n vector

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.

A-T orifice volumetric flow rate table, q(ds,dp) — Vector of volumetric flow rate for tabular parameterization - different flow paths

[1.7e-05, 2e-05, 2.6e-05; .0035, .0045, .0053; .7, .9, 1.06; 1.96, 2.5, 3; 6, 7.7, 9.13] .* 1e-3 m^3/s (default) | M-by-N matrix

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

Spool position at maximum P-T orifice area — Spool offset at maximum area between ports P and T

5e-3 m (default) | scalar

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.

P-T spool travel between closed and open orifice — Maximum stroke for the spool between ports P and T

0.005 m (default) | positive scalar

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.

P-T maximum orifice area — Maximum area between ports P and T

1e-4 m^2 (default) | positive scalar

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.

P-T orifice spool travel vector — Vector of valve opening distances

[0, .002, .004, .007, .017] m (default) | 1-by-n vector

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.

P-T orifice area vector — Vector of valve opening areas

[1e-09, 2.0352e-07, 4.0736e-05, .00011438, .00034356] m^2 (default) | 1-by-n vector

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.

P-T orifice spool travel vector, ds — Vector of valve opening distances

[0, .002, .004, .007, .017] m (default) | 1-by-n vector

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.

P-T orifice pressure drop vector, dp — Vector of pressure drop values over the valve

[.3, .5, .7] MPa (default) | 1-by-n vector

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.

P-T orifice volumetric flow rate table, q(ds,dp) — Vector of volumetric flow rate for tabular parameterization - different flow paths

[1.7e-05, 2e-05, 2.6e-05; .0035, .0045, .0053; .7, .9, 1.06; 1.96, 2.5, 3; 6, 7.7, 9.13] .* 1e-3 m^3/s (default) | M-by-N matrix

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 faults — Fault option

Off (default) | On

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.

Spool position when faulted — Set faulted characteristics

Positive (default) | Negative | Maintain last value

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.

Fault trigger — External trigger option

Off (default) | Fault when Tr >= 0.5

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.

Simulation time for fault event — Time at which faulting is triggered

5 s (default) | positive scalar

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.

Model Examples

Drill-Ream Actuator

An actuator that drives a machine tool working unit performing a sequence of three technological operations: coarse drilling, fine drilling, and reaming. The actuator speed is controlled by one of three pressure-compensated flow control valves metering out return flow from the cylinder. The selection of an appropriate flow control is performed by directional valves that are activated by a control unit.

Lubrication System

A simplified version of a lubrication system fed with the centrifugal pump. The system consists of five major units: Pump Unit, Scavenge Unit, Heat Exchanger Manifold, Nozzle Manifold, and Control Unit. Both the pump and the scavenge unit are built around the centrifugal pump. The Scavenge Unit collects fluid discharged by nozzles and pumps it back into the reservoir of the Pump Unit. The Control Unit generates commands to bypass either the heat exchanger, represented as a local resistance, or the nozzles block. In a real system, these commands are generated by temperature sensors installed in lubrication cavities.