Engee documentation

Single-Acting Actuator (IL)

A one-way linear actuator in an isothermal fluid network.

blockType: EngeeFluids.IsothermalLiquid.Actuators.TranslationalSingleActing

single acting actuator il

Path in the library:

/Physical Modeling/Fluids/Isothermal Liquid/Actuators/Single-Acting Actuator (IL)

Description

Block Single-Acting Actuator (IL) simulates a drive that converts the fluid pressure of port A into mechanical force in port R due to the reciprocating motion of the piston. The piston movement is limited by the rigid stop model. The position of the piston is calculated inside the system and transmitted to port p.

Parameters Initial piston displacement, Fluid dynamic compressibility and Environment pressure set by the user. Fluid inertia and mechanical inertia are not taken into account.

Moving

The movement of the piston is determined by the displacement of port R relative to port C. Parameter Value Mechanical orientation determines the direction of displacement of the piston. The movement of the piston is neutral (equal to 0), when the volume of the camera is Dead volume.

The hard limiter model

The limits of the piston stroke are proposed to be modeled in four ways. To do this, the block uses the same model as the block Translational Hard Stop, and takes into account the damping and stiffness coefficients at both ends of the piston stroke.

In the extreme positions of the piston, a rigid limiter force arises, the range of which is within Transition region for Piston stroke or Initial piston displacement. Outside of this area .

The damper

The block can simulate shock absorption in the extreme positions of the piston. If the check box is selected, Cylinder end cushioning, the block takes into account the deceleration of the piston as it approaches the maximum value of the stroke length of the piston, determined by the parameter Piston stroke. For more information about the hydraulic cylinder damper, see the section Cylinder Cushion (IL).

Friction

If the check box is selected Cylinder friction, then the block takes into account the friction of the piston during its movement, while the resulting friction is a combination of the effects of Strobeck, Coulomb and viscosity. The unit measures the pressure difference between the pressure in the chamber and the ambient pressure. For more information about the friction model and its limitations, see the section Cylinder Friction (IL).

The leak

If the checkbox is selected in the block Leakage, then leaks through the gap between the chamber and the drive piston are additionally taken into account. For more information about leak modeling, see the section Laminar Leakage (IL).

The expense is calculated as:

where

  • — kinematic viscosity of the liquid;

  • — the length of the piston, p - ;

  • — port pressure A;

  • — ambient pressure, which is set by the parameter Environment pressure specification;

  • is the diameter of the cylinder, which can be written as , where — parameter value Piston-cylinder clearance;

  • — the diameter of the piston, which is calculated as , where — parameter value Piston cross-sectional area.

Numerical smoothing of area and pressure values

The computational stability of the simulation is optionally regulated by the parameter Smoothing factor. If Smoothing factor If it is not equal to zero, then the value of the area of the damper opening and the pressure of the check valve are smoothed out. The hole area changes smoothly between the parameters Leakage area between plunger and cushion sleeve and Cushion plunger cross-sectional area. The valve pressure changes smoothly in the range between the parameters Check valve cracking pressure differential and Check valve maximum pressure differential.

Block sub-components

Block Single-Acting Actuator (IL) It consists of four library blocks Isothermal fluid and two library blocks Mechanics:

The structural diagram of the drive is shown in the diagram.

single acting actuator il 1

Ports

Conserving

# A — inlet or outlet for fluid flow
isothermal liquid

Details

The port of an isothermal liquid corresponding to the inlet or outlet.

Program usage name

port

# R — actuator piston
translational mechanics

Details

A mechanical progressive port corresponding to the actuator piston.

Program usage name

rod_flange

# C — drive housing
translational mechanics

Details

Mechanical progressive port corresponding to the actuator housing.

Program usage name

case_flange

Output

# p — piston position
scalar

Details

Piston position in m.

Data types

Float64.
Complex numbers support

No

Parameters

Actuator

# Mechanical orientation — the direction of movement of the piston
Pressure at A causes positive displacement of R relative to C | Pressure at A causes negative displacement of R relative to C

Details

Determines the direction of displacement of the piston. Options to choose from:

  • Pressure at A causes positive displacement of R relative to C — the movement of the piston is positive if the volume of liquid in port A increases. This corresponds to the movement of the rod out of the cylinder.

  • Pressure at A causes negative displacement of R relative to C — the movement of the piston is negative if the volume of liquid in port A increases. This corresponds to the movement of the rod inside the cylinder.

Values

Pressure at A causes positive displacement of R relative to C | Pressure at A causes negative displacement of R relative to C
Default value

Pressure at A causes positive displacement of R relative to C
Program usage name

orientation
Evaluatable

No

# Piston cross-sectional area — the cross-sectional area of the piston rod
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The cross-sectional area of the piston rod.

Units

m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac
Default value

0.01 m^2
Program usage name

piston_area
Evaluatable

Yes

# Piston stroke — stroke of the piston
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The maximum possible displacement of the piston.

Units

m | um | mm | cm | km | in | ft | yd | mi | nmi
Default value

0.1 m
Program usage name

stroke
Evaluatable

Yes

# Dead volume — the volume of liquid at which the movement of the piston is 0
m^3 | um^3 | mm^3 | cm^3 | km^3 | ml | l | gal | igal | in^3 | ft^3 | yd^3 | mi^3

Details

The volume of liquid at the value of the piston displacement 0. This volume of liquid corresponds to the position of the piston, at which it is located at the top in relation to the end cap of the actuator.

Units

m^3 | um^3 | mm^3 | cm^3 | km^3 | ml | l | gal | igal | in^3 | ft^3 | yd^3 | mi^3
Default value

1e-05 m^3
Program usage name

dead_volume
Evaluatable

Yes

# Environment pressure specification — the method of setting the ambient pressure
Atmospheric pressure | Specified pressure

Details

The method of setting the ambient pressure. Option Atmospheric pressure sets the ambient pressure equal to 0.101325 MPa.

Values

Atmospheric pressure | Specified pressure
Default value

Atmospheric pressure
Program usage name

pressure_type
Evaluatable

No

# Environment pressure — ambient pressure
Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg

Details

User-defined ambient pressure.

Dependencies

To use this parameter, set for the parameter Environment pressure specification meaning Specified pressure.

Units

Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg
Default value

0.101325 MPa
Program usage name

p_specified
Evaluatable

Yes

Hard Stop

# Hard stop model — choosing a rigid stop model
Stiffness and damping applied smoothly through transition region, damped rebound | Full stiffness and damping applied at bounds, undamped rebound | Full stiffness and damping applied at bounds, damped rebound | Based on coefficient of restitution

Details

Selecting a model for the force acting on the piston when it is in extreme positions. For more information, see the block Translational Hard Stop.

Values

Stiffness and damping applied smoothly through transition region, damped rebound | Full stiffness and damping applied at bounds, undamped rebound | Full stiffness and damping applied at bounds, damped rebound | Based on coefficient of restitution
Default value

Stiffness and damping applied smoothly through transition region, damped rebound
Program usage name

hardstop_model
Evaluatable

No

# Hard stop stiffness coefficient — stiffness coefficient
N/m | mN/m | kN/m | MN/m | GN/m | kgf/m | lbf/ft | lbf/in

Details

The coefficient of piston stiffness.

Units

N/m | mN/m | kN/m | MN/m | GN/m | kgf/m | lbf/ft | lbf/in
Default value

1e10 N/m
Program usage name

k_hard_stop
Evaluatable

Yes

# Hard stop damping coefficient — damping coefficient
N*s/m | kgf*s/m | lbf*s/ft | lbf*s/in

Details

Piston damping coefficient.

Units

N*s/m | kgf*s/m | lbf*s/ft | lbf*s/in
Default value

150.0 N*s/m
Program usage name

C_hard_stop
Evaluatable

Yes

# Transition region — the range of action of the rigid stop model
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The area of operation of the rigid stop. Outside of this range for the extreme positions of the piston Hard stop model it is not applied, and the additional force from the stop side does not act on the piston.

Dependencies

To use this parameter, set for the parameter Hard stop model meaning Stiffness and damping applied smoothly through transition region, damped rebound.

Units

m | um | mm | cm | km | in | ft | yd | mi | nmi
Default value

0.1 mm
Program usage name

transition_region
Evaluatable

Yes

# Coefficient of restitution — the ratio of the final and initial relative velocity between the rod and the stop after a collision

Details

The ratio of the final and initial relative velocity between the rod and the stop after the rod rebounds.

Dependencies

To use this parameter, set for the parameter Hard stop model meaning Based on coefficient of restitution.

Default value

0.7
Program usage name

restitution_coefficient
Evaluatable

Yes

# Static contact speed threshold — threshold value of the relative velocity between the rod and the stop before the collision
m/s | mm/s | cm/s | km/s | m/hr | km/hr | in/s | ft/s | mi/s | ft/min | mi/hr | kn

Details

The threshold value of the relative velocity between the rod and the stop before the collision. If the rod hits the housing at a speed lower than the value of this parameter, they remain in contact. Otherwise, the rod bounces off. To avoid simulating static contact between the rod and the housing, set this parameter to 0.

Dependencies

To use this parameter, set for the parameter Hard stop model meaning Based on coefficient of restitution.

Units

m/s | mm/s | cm/s | km/s | m/hr | km/hr | in/s | ft/s | mi/s | ft/min | mi/hr | kn
Default value

0.001 m/s
Program usage name

v_static_contact_threshold
Evaluatable

Yes

# Static contact release force threshold — the threshold value of the force required to transition from the contact state to the free state
N | nN | uN | mN | kN | MN | GN | dyn | lbf | kgf

Details

The minimum force required to remove the rod from the static contact state.

Dependencies

To use this parameter, set for the parameter Hard stop model meaning Based on coefficient of restitution.

Units

N | nN | uN | mN | kN | MN | GN | dyn | lbf | kgf
Default value

0.001 N
Program usage name

F_static_contact_release_threshold
Evaluatable

Yes

Cushion

# Cylinder end cushioning — option to simulate piston braking due to the action of a damper

Details

Whether the deceleration of the piston in its extreme positions is taken into account. For more information, see the see the block Cylinder Cushion (IL).

Default value

false (switched off)
Program usage name

enable_cylinder_cushion
Evaluatable

No

# Cushion plunger cross-sectional area — the cross-sectional area of the shock-absorbing plunger
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The cross-sectional area of the shock-absorbing plunger.

Dependencies

To use this option, check the box Cylinder end cushioning.

Units

m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac
Default value

0.0001 m^2
Program usage name

plunger_area
Evaluatable

Yes

# Cushion plunger length — the length of the shock-absorbing plunger
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The length of the shock-absorbing plunger.

Dependencies

To use this option, check the box Cylinder end cushioning.

Units

m | um | mm | cm | km | in | ft | yd | mi | nmi
Default value

0.001 m
Program usage name

plunger_length
Evaluatable

Yes

# Cushion orifice area — the area of the opening between the damper chambers
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The area of the opening between the damper chambers.

Dependencies

To use this option, check the box Cylinder end cushioning.

Units

m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac
Default value

1e-06 m^2
Program usage name

cushioning_valve_area
Evaluatable

Yes

# Leakage area between plunger and cushion sleeve — the area of the gap between the damper plunger and the bushing
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The area of the gap between the damper plunger and the bushing. The parameter supports computational stability of the simulation, ensuring continuity of the flow.

Dependencies

To use this option, check the box Cylinder end cushioning.

Units

m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac
Default value

1e-07 m^2
Program usage name

plunger_leakage_area
Evaluatable

Yes

# Check valve cracking pressure differential — the pressure drop at which the check valve begins to open
Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg

Details

The pressure at which the valve is triggered. When the pressure difference in port A and If the value of this parameter is equal to or exceeds, the non-return valve of the damper begins to open.

Dependencies

To use this option, check the box Cylinder end cushioning.

Units

Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg
Default value

0.01 MPa
Program usage name

delta_p_crack
Evaluatable

Yes

# Check valve maximum pressure differential — the pressure drop required to fully open the check valve
Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg

Details

Maximum pressure drop of the damper check valve. This parameter sets the upper pressure limit so that the system pressure remains realistic.

Dependencies

To use this option, check the box Cylinder end cushioning.

Units

Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg
Default value

0.1 MPa
Program usage name

delta_p_max
Evaluatable

Yes

# Check valve maximum area — the area of the fully open check valve
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The cross-sectional area of the non-return valve opening in the fully open position.

Dependencies

To use this option, check the box Cylinder end cushioning.

Units

m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac
Default value

0.0001 m^2
Program usage name

check_valve_max_area
Evaluatable

Yes

# Check valve leakage area — leakage area with the check valve fully closed
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The total area of possible leaks when the check valve is fully closed. Any area less than this value increases smoothly to the specified leakage area. This value contributes to computational robustness by maintaining continuity of flow.

Dependencies

To use this option, check the box Cylinder end cushioning.

Units

m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac
Default value

1e-10 m^2
Program usage name

check_valve_leakage_area
Evaluatable

Yes

# Smoothing factor — numerical smoothing factor

Details

The continuous smoothing coefficient, which ensures smooth opening by correcting for the valve characteristics in the almost open and almost closed positions. Set a non-zero value less than one to increase the stability of the simulation.

Dependencies

To use this option, check the box Cylinder end cushioning.

Default value

0.01
Program usage name

smoothing_factor
Evaluatable

Yes

Friction

# Cylinder friction — option to simulate friction during piston movement

Details

Whether the friction of the piston is taken into account during movement. The friction force of the block consists of the Shtribek force, Coulomb force and viscosity. For more information, see the section Cylinder Friction (IL).

Default value

false (switched off)
Program usage name

enable_friction
Evaluatable

No

# Breakaway to Coulomb friction force ratio — the ratio of the separation force to the Coulomb friction force

Details

The ratio of the separation force to the Coulomb friction force.

Dependencies

To use this option, check the box Cylinder friction.

Default value

1.2
Program usage name

Coulomb_breakaway_ratio
Evaluatable

Yes

# Breakaway friction velocity — threshold of movement against the friction force
m/s | mm/s | cm/s | km/s | m/hr | km/hr | in/s | ft/s | mi/s | ft/min | mi/hr | kn

Details

The threshold value of the speed at which movement begins against the friction force.

Dependencies

To use this option, check the box Cylinder friction.

Units

m/s | mm/s | cm/s | km/s | m/hr | km/hr | in/s | ft/s | mi/s | ft/min | mi/hr | kn
Default value

0.1 m/s
Program usage name

v_breakaway
Evaluatable

Yes

# Preload force — the initial force in the cylinder, which occurs during the assembly of the seal, N
N | nN | uN | mN | kN | MN | GN | dyn | lbf | kgf

Details

The initial force in the cylinder under the action of the seal assembly. The block uses this parameter to calculate the Coulomb friction force.

Dependencies

To use this option, check the box Cylinder friction.

Units

N | nN | uN | mN | kN | MN | GN | dyn | lbf | kgf
Default value

20.0 N
Program usage name

F_preload
Evaluatable

Yes

# Coulomb friction force coefficient — coefficient of Coulomb friction force
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac | N/Pa

Details

The coefficient of Coulomb friction force.

Dependencies

To use this option, check the box Cylinder friction.

Units

m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac | N/Pa
Default value

1e-06 N/Pa
Program usage name

Coulomb_coefficient
Evaluatable

Yes

# Viscous friction coefficient — coefficient of viscous friction
N*s/m | kgf*s/m | lbf*s/ft | lbf*s/in

Details

Coefficient of viscous friction.

Dependencies

To use this option, check the box Cylinder friction.

Units

N*s/m | kgf*s/m | lbf*s/ft | lbf*s/in
Default value

100.0 N*s/m
Program usage name

viscous_coefficient
Evaluatable

Yes

Leakage

# Leakage — ring leak simulation option

Details

Are leaks through the annular gap between the drive chamber and the piston taken into account under reference environmental conditions? The flow through the gap is laminar. For more information, see the section Laminar Leakage (IL).

Default value

false (switched off)
Program usage name

enable_leakage
Evaluatable

No

# Piston-cylinder clearance — radial clearance
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The radial distance between the piston rod and the cylinder body.

Dependencies

To use this option, check the box Leakage.

Units

m | um | mm | cm | km | in | ft | yd | mi | nmi
Default value

0.0001 m
Program usage name

clearance
Evaluatable

Yes

# Piston head length — piston head length
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The length of the piston head.

Dependencies

To use this option, check the box Leakage.

Units

m | um | mm | cm | km | in | ft | yd | mi | nmi
Default value

0.01 m
Program usage name

piston_length
Evaluatable

Yes

Initial Conditions

# Initial piston displacement — the initial position of the piston
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The position of the piston at the beginning of the simulation.

Units

m | um | mm | cm | km | in | ft | yd | mi | nmi
Default value

0.0 m
Program usage name

offset
Evaluatable

Yes

# Fluid dynamic compressibility — the option of modeling the compressibility of a liquid

Details

Accounting for changes in the density of a liquid due to its compressibility. If the check box is selected Fluid dynamic compressibility, then the changes associated with the mass flow rate of the fluid in the block are calculated in addition to the density changes associated with pressure changes. In the library Isothermal liquid all blocks calculate density as a function of pressure.

Default value

true (switched on)
Program usage name

dynamic_compressibility
Evaluatable

No

# Initial liquid pressure — initial fluid pressure for compressible fluids
Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg

Details

The initial fluid pressure for compressible fluids.

Dependencies

To use this option, check the box Fluid dynamic compressibility.

Units

Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg
Default value

0.101325 MPa
Program usage name

p_start
Evaluatable

Yes