2-Way Directional Valve (IL)

2-way flow control valve in an isothermal liquid systems

Since R2020a

Libraries:
Simscape / Fluids / Isothermal Liquid / Valves & Orifices / Directional Control Valves

Description

The 2-Way Directional Valve (IL) block represents a two-way valve, such as a shut-off valve. Use this block to simulate a flow-reducing control element that responds to pressures in another part of the system.

The block uses a variable orifice to control the flow between ports A and B. The physical signal at port S triggers the spool motion to open or shut the valve. For more details about how the block calculates flow rate through a variable orifice, see Orifice (IL).

Orifice Parameterizations

You can parameterize the valve opening linearly or by using tabulated data.

Linear

When you set Orifice parameterization to Linear - Area vs. spool travel, the opening area is a linear function of the spool travel distance.

$A_{o r i f i c e} = \frac{(A_{\max} - A_{l e a k})}{Δ S_{\max}} Δ S + A_{l e a k},$

where

A_orifice is the opening area.
ΔS is the spool travel distance input at port S. $Δ S = S - S_{\max} + Δ S_{\max} .$
ΔS_max is the value of the Spool travel between closed and open orifice parameter.
A_Leak is the value of the Leakage area parameter.
A_max is the value of the Maximum orifice area parameter.

Note the linear scaling from A_Leak to A_max in the figure.

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 Smoothing factor parameter. If the Smoothing factor parameter is nonzero, the block smoothly saturates the opening area between A_leak and A_max. For more information, see Numerical Smoothing.

Tabulated

When you set Orifice parameterization to Tabulated data - Area vs. spool travel, the block uses the Spool travel vector and Orifice area vector parameters to define the relationship between A_orifice and ΔS by interpolation. A_leak and A_max are the first and last parameters of the Orifice area vector parameter, respectively.

When you set Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop, the block uses the Volumetric flow rate table, q(ds,dp), Pressure drop vector, dp, and Spool travel vector, ds parameters to define the volumetric flow rate, q(ΔS,p).

Visualize Orifice Openings

To visualize the spool offsets and displacement, right-click the block and select Fluids > Plot Valve Characteristics. The plot shows the valve open area or volumetric flow rate as a function of spool position.

To update the data after changing the block parameters, click Reload Data in the figure window.

This figure shows the valve configuration with:

Spool position at maximum orifice area set to 2e-3 m.
Spool travel between closed and open orifice set to 6e-3 m.

All other parameters are at the default values.

Plot of area versus spool position for each orifice.

Faults

To model a fault, in the Faults section, click the Add fault hyperlink next to the fault that you want to model. Use the fault parameters to specify the fault properties. For more information about fault modeling, see Introduction to Simscape Faults.

You can choose the type of fault by using the Spool position when faulted parameter:

Negative — The block freezes the valve at its smallest value. The table shows which value the block uses depending on the setting of the Orifice parameterization parameter.

Orifice parameterization Parameter Setting	Freeze Position Value
`Linear - Area vs. spool travel`	Leakage area parameter
`Tabulated data - Area vs. spool travel`	First element of the Orifice area vector parameter
`Tabulated data - Volumetric flow rate vs. spool travel and pressure drop`	First row of the Volumetric flow rate table, q(ds,dp) parameter

Positive — The valve freezes at its largest value. The table shows which value the block uses depending on the setting of the Orifice parameterization parameter.

Orifice parameterization Parameter Setting	Freeze Position Value
`Linear - Area vs. spool travel`	Maximum opening area parameter
`Tabulated data - Area vs. spool travel`	Last element of the Orifice area vector parameter
`Tabulated data - Volumetric flow rate vs. spool travel and pressure drop`	Last row of the Volumetric flow rate table, q(ds,dp) parameter

Maintain last value — The valve freezes at its last value. The table shows which value the block uses depending on the setting of the Orifice parameterization parameter.

Orifice parameterization Parameter Setting	Freeze Position Value
`Linear - Area vs. spool travel`	The valve open area when the trigger occurred
`Tabulated data - Area vs. spool travel`	The valve open area when the trigger occurred
`Tabulated data - Volumetric flow rate vs. spool travel and pressure drop`	Current position

When you set Orifice parameterization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop, the volumetric flow rate continues to change according to pressure changes in the valve after the valve freezes.

Due to numerical smoothing at the extremes of the valve area, in the linear parameterization, the minimum area that he block uses is larger than the Leakage area, and the maximum is smaller than the Maximum orifice area, in proportion to the Smoothing factor value. For more information, see Numerical Smoothing.

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.

Open Model

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.

Open Model

Washing Machine Fault Analysis

Model a washing machine and introduce a fault in its operation. The machine water supply faults at a specific time and this example models the system response under this scenario. The electric motor switches off and the machine operation is aborted by discharging the partially filled outer drum.

Open Model

Ports

Conserving

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A — Liquid port
isothermal liquid

Isothermal liquid conserving port.

B — Liquid port
isothermal liquid

Isothermal liquid conserving port.

Input

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S — Spool displacement, m
physical signal

Physical signal associated with the spool displacement, in m. A positive value causes the valve to open.

Parameters

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Model Parameterization

Orifice parameterization — Opening area relationship
`Linear - area vs. spool travel` (default) | `Tabulated data - Area vs. spool travel` | `Tabulated data - Volumetric flow rate vs. spool travel and pressure drop`

Method the block uses to calculate the valve flow area. To learn more, see Orifice Parameterizations.

Spool position at maximum orifice area — Spool offset at maximum area
`5e-3` `m` (default) | positive scalar

Position of the spool travel member when the valve is fully open. The default value represents a zero-lapped system. A positive, nonzero value represents an underlapped, or partially closed, system. A negative, nonzero value represents an overlapped system where the valve remains open over a range of displacements.

Spool travel between closed and open orifice — Maximum spool stroke
`5e-3` `m` (default) | positive scalar

Spool offset at the maximum valve opened area.

Dependencies

To enable this parameter, set Orifice parametrization to Linear - area vs. spool travel.

Maximum orifice area — Area of fully open valve
`1e-4` `m^2` (default) | positive scalar

Maximum valve area experienced during simulation.

Dependencies

To enable this parameter, set Orifice parametrization to Linear - area vs. spool travel.

Leakage area — Valve gap area when in fully closed position
`1e-10` `m^2` (default) | positive scalar

Sum of all gaps when the valve is in the fully closed position. The block maintains any area smaller than this value at the specified leakage area. This parameter contributes to numerical stability by maintaining continuity in the flow.

Dependencies

To enable this parameter, set Orifice parametrization to Linear - area vs. spool travel.

Spool travel vector — Spool opening distance values
`[0, .002, .004, .007, .017]` `m` (default) | vector

Vector of control member travel distances. A positive value opens the valve. The values in this vector correspond one-to-one to values in the Orifice area vector parameter. The values must ascend from 0. The block interpolates the points linearly.

Dependencies

To enable this parameter, set Orifice parametrization to Tabulated data - Area vs. spool travel.

Orifice area vector — Valve opening area values
`[1e-09, 2.0352e-07, 4.0736e-05, .00011438, .00034356]` `m^2` (default) | vector

Vector of valve area values for the tabular parametrization of opening area. The values in this vector correspond one-to-one with the elements in the Spool travel vector parameter. The first element of this vector is the leakage area, and the last element is the maximum valve area. The block interpolates the points linearly.

Dependencies

To enable this parameter, set Orifice parametrization to Tabulated data - Area vs. spool travel.

Spool travel vector, ds — Tabular spool opening distance values
`[0, .002, .004, .007, .017]` `m` (default) | vector

Vector of control member travel distances. 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 ascend from 0. The block interpolates the points linearly.

Dependencies

To enable this parameter, set Orifice parametrization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

Pressure drop vector, dp — Tabular pressure drop values
`[.3, .5, .7]` `MPa` (default) | vector

Vector of pressure drop values for the volumetric flow rate. The pressure drop vector forms an independent axis with the Spool travel vector, ds parameter for the 3-D dependent Volumetric flow rate table, q(ds,dp) parameter. The values must be positive and ascending. The block interpolates the points linearly

Dependencies

To enable this parameter, set Orifice parametrization to Tabulated data -Volumetric flow rate vs. spool travel and pressure drop.

Volumetric flow rate table, q(ds,dp) — Volumetric flow rate for given spool travel and pressure drop
`[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]` `m^3/s` (default) | 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 correlated vectors:

M is the number of elements in the Spool travel vector, ds parameter.
N is the number of elements in the Pressure drop vector, dp parameter.

Dependencies

To enable this parameter, set Orifice parametrization to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.

Discharge coefficient — Discharge coefficient
`0.64` (default) | positive scalar

Discharge loss for a hydraulic structure. The default discharge coefficient for an valve in Simscape™ Fluids™ is 0.64.

Dependencies

To enable this parameter, set Orifice parametrization to either:

Tabulated data - Area vs. spool travel
Linear - area vs. spool travel

Critical Reynolds number — Upper Reynolds number limit for laminar flow
`150` (default) | positive scalar

Upper Reynolds number limit for laminar flow through the valve.

Dependencies

To enable this parameter, set Orifice parametrization to either:

Tabulated data - Area vs. spool travel
Linear - area vs. spool travel

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.

Dependencies

To enable this parameter, set Orifice parametrization to Linear - area vs. spool travel.

Pressure recovery — Whether to account for pressure increase in area expansions
`on` (default) | `off`

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

Cross-sectional area at ports A and B — Valve area at conserving ports
`inf` `m^2` (default) | positive scalar

Cross-sectional area at ports A and B. The block uses this area in the pressure-flow rate equation to determine the volumetric flow rate through the valve.

Dependencies

To enable this parameter, set Orifice parametrization to either:

Tabulated data - Area vs. spool travel
Linear - area vs. spool travel

Faults

2-Way Directional Valve Area fault — Option to model spool position fault
`Add fault`

Option to model a spool position fault in the block. To add a fault, click the Add fault hyperlink. When a fault occurs, the valve area normally set by the opening parameterization is set based on the value specified in the Spool position when faulted parameter.

Spool position when faulted — Faulted valve characteristics
`Positive` (default) | `Negative` | `Maintain last value`

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 the fault triggers.

Dependencies

To enable this parameter, click the Add fault hyperlink.

Extended Capabilities

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

Version History

Introduced in R2020a

expand all

R2024a: Model faults with the Simscape faults interface

The 2-Way Directional Valve (IL) block now supports the Simscape faults interface. To learn more, see Introduction to Simscape Faults.

2-Way Directional Valve (IL)

Description

Orifice Parameterizations

Visualize Orifice Openings

Faults

Examples

Drill-Ream Actuator

Lubrication System

Washing Machine Fault Analysis

Ports

Conserving

A — Liquid port isothermal liquid

B — Liquid port isothermal liquid

Input

S — Spool displacement, m physical signal

Parameters

Model Parameterization

Orifice parameterization — Opening area relationship Linear - area vs. spool travel (default) | Tabulated data - Area vs. spool travel | Tabulated data - Volumetric flow rate vs. spool travel and pressure drop

Spool position at maximum orifice area — Spool offset at maximum area 5e-3 m (default) | positive scalar

Spool travel between closed and open orifice — Maximum spool stroke 5e-3 m (default) | positive scalar

Dependencies

Maximum orifice area — Area of fully open valve 1e-4 m^2 (default) | positive scalar

Dependencies

Leakage area — Valve gap area when in fully closed position 1e-10 m^2 (default) | positive scalar

Dependencies

Spool travel vector — Spool opening distance values [0, .002, .004, .007, .017] m (default) | vector

Dependencies

Orifice area vector — Valve opening area values [1e-09, 2.0352e-07, 4.0736e-05, .00011438, .00034356] m^2 (default) | vector

Dependencies

Spool travel vector, ds — Tabular spool opening distance values [0, .002, .004, .007, .017] m (default) | vector

Dependencies

Pressure drop vector, dp — Tabular pressure drop values [.3, .5, .7] MPa (default) | vector

Dependencies

Volumetric flow rate table, q(ds,dp) — Volumetric flow rate for given spool travel and pressure drop [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] m^3/s (default) | matrix

Dependencies

Discharge coefficient — Discharge coefficient 0.64 (default) | positive scalar

Dependencies

Critical Reynolds number — Upper Reynolds number limit for laminar flow 150 (default) | positive scalar

Dependencies

Smoothing factor — Numerical smoothing factor 0.01 (default) | positive scalar in the range [0,1]

Dependencies

Pressure recovery — Whether to account for pressure increase in area expansions on (default) | off

Cross-sectional area at ports A and B — Valve area at conserving ports inf m^2 (default) | positive scalar

Dependencies

Faults

2-Way Directional Valve Area fault — Option to model spool position fault Add fault

Spool position when faulted — Faulted valve characteristics Positive (default) | Negative | Maintain last value

Dependencies

Extended Capabilities

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

Version History

R2024a: Model faults with the Simscape faults interface

See Also

Topics

A — Liquid port
isothermal liquid

B — Liquid port
isothermal liquid

S — Spool displacement, m
physical signal

Orifice parameterization — Opening area relationship
`Linear - area vs. spool travel` (default) | `Tabulated data - Area vs. spool travel` | `Tabulated data - Volumetric flow rate vs. spool travel and pressure drop`

Spool position at maximum orifice area — Spool offset at maximum area
`5e-3` `m` (default) | positive scalar

Spool travel between closed and open orifice — Maximum spool stroke
`5e-3` `m` (default) | positive scalar

Maximum orifice area — Area of fully open valve
`1e-4` `m^2` (default) | positive scalar

Leakage area — Valve gap area when in fully closed position
`1e-10` `m^2` (default) | positive scalar

Spool travel vector — Spool opening distance values
`[0, .002, .004, .007, .017]` `m` (default) | vector

Orifice area vector — Valve opening area values
`[1e-09, 2.0352e-07, 4.0736e-05, .00011438, .00034356]` `m^2` (default) | vector

Spool travel vector, ds — Tabular spool opening distance values
`[0, .002, .004, .007, .017]` `m` (default) | vector

Pressure drop vector, dp — Tabular pressure drop values
`[.3, .5, .7]` `MPa` (default) | vector

Volumetric flow rate table, q(ds,dp) — Volumetric flow rate for given spool travel and pressure drop
`[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]` `m^3/s` (default) | matrix

Discharge coefficient — Discharge coefficient
`0.64` (default) | positive scalar

Critical Reynolds number — Upper Reynolds number limit for laminar flow
`150` (default) | positive scalar

Smoothing factor — Numerical smoothing factor
`0.01` (default) | positive scalar in the range [0,1]

Pressure recovery — Whether to account for pressure increase in area expansions
`on` (default) | `off`

Cross-sectional area at ports A and B — Valve area at conserving ports
`inf` `m^2` (default) | positive scalar

2-Way Directional Valve Area fault — Option to model spool position fault
`Add fault`

Spool position when faulted — Faulted valve characteristics
`Positive` (default) | `Negative` | `Maintain last value`

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