M-Way N-Position Directional Valve (IL)

M-way, N-position valve in an isothermal liquid network

Since R2022b

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

Description

The M-Way N-Position Directional Valve (IL) block represents a spool-operated directional valve with an arbitrary configuration of ports, spool positions, and orifices. The block accepts up to ten ports, ten spool positions, and 20 orifices. Valves with many configurations are most common in construction, agriculture, and some vehicle applications. This block simplifies complex parameterizations by allowing you to apply the same area characteristics to all flow paths. You can also individually specify the area characteristics for each flow path. You can parameterize the valve by specifying the opening area or by using tabulated data that represents volumetric flow rate for a fully open orifice at varied pressure drops. The block uses a variable orifice to control the flow between a given pair of connected ports. 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).

You can generate a characteristic plot of the valve by right-clicking the block and selecting Fluids > Plot Valve Characteristics. To updated the plot after changing the block parameters, click the Reload Data button. You can control the shape of the characteristic plot. To select which lines are visible, click the appropriate orifice on the legend.

The default valve characteristic plot is:

The figure indicates locations A1, A2, B1, and B2.

Position 1 is at spool travel of -1 mm. Position 2 is at spool travel of 0 mm, and Position 3 is at spool travel of 1 mm. Locations A1 and A2 represent the left- and right-side transition regions of the orifice opening area, respectively. Locations B1 and B2 represent the left- and right-side fully open regions of the orifice opening area, respectively. The current spool position is the separation between B1 and B2. When you set Area characteristics to Identical for all flow paths.

• A1 = (distance between spool positions 1 and 2) * (value of the Inter-position spool travel fraction for which orifices transition between open-closed parameter)

• A2 = (distance between spool positions 2 and 3) * (value of the Inter-position spool travel fraction for which orifices transition between open-closed parameter)

• B1 = (distance between spool positions 1 and 2) * (value of the Inter-position spool travel fraction for which orifices remain fully open parameter)

• B2 = (distance between spool positions 2 and 3) * (value of the Inter-position spool travel fraction for which orifices remain fully open parameter)

When you set Area characteristics to Different for each flow path:

• A1 = A2 = value of the Spool travel for which orifice 2 transitions between open-closed parameter.

• B1 = B2 = value of the Spool travel for which orifice 2 remains fully open parameter.

Orifice Parameterization

When you set Area parameterization to Different for each flow path, you can parameterize each orifice by using the parameters in the Orifice 1,…,20 sections. For example, if you set Number of orifices to 3, the block includes sections for Orifice 1, Orifice 2, and Orifice 3. Each section has the same parameter names followed by the number for that section.

The block icon updates automatically to indicate the orifice configuration, which you control with the appropriate Ports connected by orifice... parameter. If you connect one odd-numbered port to one even-numbered port, the block icon shows an arrow that points to the second listed port. The block icon indicates when a parameterization is invalid.

Assumptions and Limitations

• The block supports only linearly varying opening areas.

• The block assumes that each orifice has a symmetric opening and closing about the spool position when you set Area characteristics to Different for each flow path.

• The block assumes that each orifice has a symmetric opening and closing scaled with the spacing of the Spool travel at each spool position index parameter when you set Area characteristics to Identical for each flow path.

Ports

Input

S — Spool displacement, m

physical signal

Physical signal input port associated with the spool displacement, in m.

Conserving

1 — Port 1

isothermal liquid

Isothermal liquid conserving port associated with port 1.

2,...,10 — Ports with parameter dependencies

isothermal liquid

Isothermal liquid conserving ports associated with port 2 through 10, where the number of ports is equal to the Number of ports parameter.

Dependencies

To enable ports 2 through 10, set Number of ports to the number of ports you want.

Parameters

Valve Configuration

Number of ports — Number of valve ports

2 (default) | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10

Number of ports associated with the valve, M. You can select up to ten.

Number of spool positions — Number of spool positions

2 (default) | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10

Number of spool positions, N. You can select up to ten.

Number of orifices — Number of orifices

1 (default) | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20

Number of orifices. You can select up to 20.

Spool travel at each spool position index — Spool travel

[-2, 0, 2, 4] mm (default) | vector of length N

Spool travel values. Each element corresponds to a different spool position index. The length of this vector must be equal to length of the Number of spool positions parameter, N. A value of 0 represents a neutral spool position.

Area characteristics — Area characteristic parameterization option

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

Whether to apply identical or different parameterizations for each orifice.

Inter-position spool travel fraction for which orifices remain fully open — Fully open flow between spool positions

0.5 (default) | scalar in the range [0,1)

Fractional distance between adjacent spool positions for which each orifice remains at the maximum opening area.

Dependencies

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

Inter-position spool travel fraction for which orifices transition between open-closed — Spool travel from open to closed

0.1 (default) | nonnegative scalar

Fractional distance between adjacent spool positions over which the orifice area transitions between maximum area and leakage area.

Dependencies

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

Orifice parameterization — Orifice parameterization

Orifice area (default) | Tabulated data - Volumetric flow rate vs. pressure drop

Whether to parameterize each orifice by area or by using tabulated volumetric flow rate data according to pressure drop.

Maximum orifice area — Maximum orifice area

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

Maximum opening area for all orifices.

Dependencies

To enable this parameter, set Area characteristics to Identical for each flow path and Orifice parameterization to Orifice area.

Leakage area fraction — Leakage area fraction

0.01 (default) | positive scalar

Leakage area as a fraction of the value of the Maximum orifice area parameter.

Dependencies

To enable this parameter, set Orifice parameterization to Orifice area.

Cross-sectional area at ports — Cross-sectional area for all ports

inf m^2 (default) | positive scalar

Cross-sectional area for all ports.

Dependencies

To enable this parameter, set Orifice parameterization to Orifice area.

Discharge coefficient — Discharge coefficient

0.64 (default) | positive scalar

Correction factor that accounts for discharge losses in theoretical flows.

Dependencies

To enable this parameter, set Orifice parameterization to Orifice area.

Critical Reynolds number — Critical Reynolds number

150 (default) | positive scalar

Upper Reynolds number limit for laminar flow through the orifice.

Dependencies

To enable this parameter, set Orifice parameterization to Orifice area.

Smoothing factor — Numerical smoothing factor

0.01 (default) | positive scalar

Continuous smoothing factor that introduces a layer of gradual change to the flow response when the valve is in near-open or near-closed positions. Set this value to a nonzero value less than one to improve the stability of your simulation in these regimes.

Dependencies

To enable this parameter, set Orifice parameterization to Orifice area.

Pressure recovery — Option to account for pressure increases in area expansions

Off (default) | On

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

Dependencies

To enable this parameter, set Orifice parameterization to Orifice area.

Pressure drop vector — Tabulated pressure drop

[-.1, .3, .5, .7] MPa (default) | vector of length X

Tabulated pressure drop values for all orifices. The elements of this vector correspond one-to-one with the Fully open volumetric flow rate vector parameter.

Dependencies

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

Fully open volumetric flow rate vector — Tabulated volumetric flow rate

[-.0009, .0016, .002, .0024] m^3/s (default) | vector of length X

Volumetric flow rate for a fully open orifice at a given pressure drop. The elements of this vector correspond one-to-one with the Pressure drop vector parameter.

Dependencies

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

Leakage flow rate fraction — Leakage flow rate fraction

0.01 (default) | positive scalar

Leakage as a fraction of the Fully open volumetric flow rate vector parameter.

Dependencies

To enable this parameter, set Orifice parameterization to Tabulated data - Volumetric flow rate vs. pressure drop.

Orifice 1

This section includes only the parameters for orifice 1. The remaining orifice parameters are identical to orifice 1 except for their number and the cases mentioned in the parameter descriptions for orifice 1. To learn more, see Orifice Parameterization.

Ports connected by orifice 1 — Ports connected by orifice 1

[3, 2] (default) | vector of length 2

The two fluid ports connected by orifice 1. The first element is the valve port connected to the orifice A port. The second element is the valve port connected to the orifice B port. In the Simscape Results Explorer app, the variables mdot_A and mdot_B are mass flow rates into the Orifice (IL) block A and B ports, respectively. p_diff is the pressure drop from port A to port B of the orifice. In the block icon, for ports connected to a single orifice, the arrow points to the port represented by the second element of this parameter. The default values for the other orifices are:

• Orifice 2: [4, 5]

• Orifice 3: [2, 1]

• Orifice 4: [3, 4]

• Orifice 5–Orifice 20: [1, 2]

Spool position indices where orifice 1 is open — Orifice 1 open positions

[1, 4] (default) | vector of length 1 to N

Spool positions for which orifice 1 is open. The vector must be strictly monotonically increasing with values between 1 and the value of the Number of spool positions parameter. The default values for the other orifices are:

• Orifice 2: [1, 4]

• Orifice 3: [3, 4]

• Orifice 4: [3, 4]

• Orifice 5–Orifice 20: 1

Spool travel for which orifice 1 remains fully open — Fully open spool travel

1 mm (default) | nonnegative scalar

Spool travel across which the orifice maintains the maximum opening area. The center of this spool travel distance is at the value of the Spool position with open orifice 1 parameter.

Dependencies

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

Spool travel for which orifice 1 transitions between open-closed — Threshold spool travel

0.2 mm (default) | positive scalar

Spool travel across which the orifice transitions from fully open to fully closed.

Dependencies

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

Maximum area of orifice 1 — Orifice area when fully open

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

Opening area of orifice 1.

Dependencies

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

Pressure drop vector of orifice 1 — Orifice 1 pressure drop

[-.1, .3, .5, .7] MPa (default) | vector of length X

Vector of pressure drop values for orifice 1. These values correspond one-to-one with the Fully open volumetric flow rate vector of orifice 1 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. pressure drop.

Fully open volumetric flow rate vector of orifice 1 — Orifice 1 fully open volumetric flow rate

[-.0009, .0016, .002, .0024] m^3/s (default) | vector of length X

Volumetric flow rate when orifice 1 is fully open for a given pressure drop. These values correspond one-to-one with the Pressure drop vector of orifice 1 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. pressure drop.

Version History

Introduced in R2022b