4-Way 2-Position Directional Valve (IL)
Libraries:
Simscape /
Fluids /
Isothermal Liquid /
Valves & Orifices /
Directional Control Valves
Description
The 4-Way 2-Position Directional Valve (IL) block models a valve with four 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.
In some configurations, this valve resembles a 3-way valve. To set additional flow paths when the spool is in the neutral position, see the 4-Way 3-Position Directional Valve (IL) block.
Example Valve Setup
In this configuration, Negative spool position open connections
is set to P-A and B-T
. When the signal at port
S moves the spool to a negative position, the paths between
ports P and A and between ports
B and T are open to flow. The paths
between ports P and B and ports
A and T are closed to flow:
In this configuration, Positive spool position open connections
is set to P-B and A-T
. When the signal at port
S moves the spool to a positive position, the paths between
ports P and B and between ports
A and T are open to flow and the paths
between ports P and A and between ports
B and T are closed:
Schematically, this configuration is:
The left-hand side corresponds to the positive position and the right-hand side corresponds to the negative position. The valve transitions through positions in the neutral mid-section.
Spool Displacement and Valve Configuration
The spool stroke is the amount of spool travel an orifice takes to fully open from a closed position and is defined for each orifice selected on the Valve Configuration tab. The table below shows how the stroke is calculated in accordance with the valve orifice parameterization and flow path characteristics.
Spool Stroke Based on Parameterization and Flow Path
Orifice Parameterization | Identical for All Flow Paths | Different for Each Flow Path |
---|---|---|
Linear - Area vs. spool travel | Defined by the Spool travel between closed and open orifice parameter | Defined by the Spool travel between closed and open orifice parameter, for each orifice |
Tabulated data - Area vs. spool travel | The difference between the first and last element of the Spool travel vector parameter | The difference between the first and last element of the spool travel vector parameter for each orifice |
Tabulated data - Volumetric flow rate vs. spool travel and pressure drop | The difference between the first and last element of the Spool travel vector, ds parameter | The difference between the first and last element of the spool travel vector, ds parameter for each orifice |
To see the orientation of all valve orifices, see the Visualize Orifice Openings section.
The direction of spool movement signaled at port S depends on the spool stroke and the orifice orientation:
Orifice Definition and Spool Travel Direction
Spool Position when Orifice is Open | Spool Travel, ΔS |
---|---|
Always closed (orifice is not selected in any spool position configuration) | N/A |
Always open (orifice is selected in positive, neutral, and negative spool position configurations) | N/A |
Negative | Sorifice_max + spool stroke – S |
Positive | Sorifice_max – spool stroke + S |
Where Sorifice_max is the spool position at the maximum orifice area defined for each orifice. The orifice area saturates at the leakage area when ΔS is negative and saturates at the maximum orifice area when the orifice is fully open. When the orifice is fully open, ΔS is equal to the spool stroke, so ΔS greater than the spool stroke does not further increase the orifice area.
The possible configurations of the 4-Way 2-Position Directional Valve (IL) block are shown below.
4-Way 2-Position Directional Valve Configuration
Configuration | Parameter Values |
---|---|
All four paths are closed during transition. |
|
All four paths are open during transition. |
|
A-T and B-T are closed during transition. |
|
P-A and P-B are closed during transition. |
|
P-B and B-T are closed during transition. |
|
P-A and A-T are closed during transition. |
|
P-A, P-B, and B-T are open during transition. |
|
P-A, A-T, and B-T are open during transition. |
|
P-A and P-B are closed during transition. A-T is always closed. |
|
All paths are closed during transition. |
|
A-T is open during transition. P-A is closed during transition. |
|
B-T is open during transition. P-B is closed during transition. |
|
P-A is closed during transition. |
|
P-B is closed during transition. |
|
Valve Orifice Parameterizations
The Orifice parameterization parameter sets the model for the
open area or volumetric flow rate through one or all of the valve orifices. If you
set Area characteristics to Identical for all flow
paths
, the block applies the same data for all flow paths;
otherwise, individual parameterizations are applied for the Different
for all flow paths
setting. You can model valve opening in three
ways:
Linear - area vs. spool travel
The opening area is a linear function of the spool position received as a signal at port S:
where:
ΔS is the spool travel defined in Orifice Definition and Spool Travel Direction.
Aorifice saturates at Aleak when ΔS is negative and saturates at Amax when the orifice is fully open. When the orifice is fully open, ΔS is equal to the spool stroke, so ΔS greater than the spool stroke does not further increase the orifice area.
ΔSmax is the Spool travel between closed and open orifice.
Amax is the Maximum orifice area.
Aleak is the Leakage area.
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 Aleak and Amax. For more information, see Numerical Smoothing.
Tabulated data - Area vs. spool travel
Provide spool travel vectors for your system or for individual flow paths between ports P, A, B, and T. This data will be used to calculate the relationship between the orifice area and spool displacement. 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 and a dependent, 2-D volumetric flow rate array. 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.
Visualize Orifice Openings
To visualize spool offsets and maximum 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
When the positive and negative settings in the Valve Configuration tab feature the same orifice, the orifice opening is displayed as a constant.
Each time you modify the block settings, 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 and B-T
.Negative spool position open connections is set to
P-B and A-T
.
All other spool positions are at the default values.
Example Spool Position Visualization
Faults
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.
Four 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.
Composite Structure
This block is a composite component comprising of multiple instances of the Orifice (IL) block. Refer to the Orifice (IL) block for more detail on the valve parameterizations and block calculations.
Predefined Parameterization
You can populate the block with pre-parameterized manufacturing data, which allows you to model a specific supplier component.
To load a predefined parameterization:
In the block dialog box, next to Selected part, click the "<click to select>" hyperlink next to Selected part in the block dialogue box settings.
The Block Parameterization Manager window opens. Select a part from the menu and click Apply all. You can narrow the choices using the Manufacturer drop down menu.
You can close the Block Parameterization Manager menu. The block now has the parameterization that you specified.
You can compare current parameter settings with a specific supplier component in the Block Parameterization Manager window by selecting a part and viewing the data in the Compare selected part with block section.
Note
Predefined block parameterizations use available data sources to supply parameter values. The block substitutes engineering judgement and simplifying assumptions for missing data. As a result, expect some deviation between simulated and actual physical behavior. To ensure accuracy, validate the simulated behavior against experimental data and refine your component models as necessary.
To learn more, see List of Pre-Parameterized Components.
Ports
Conserving
Input
Parameters
Extended Capabilities
Version History
Introduced in R2021a