Documentation

Variable-Displacement Pump

Variable-displacement bidirectional hydraulic pump

Library

Pumps and Motors

Description

The Variable-Displacement Pump block represents a device that extracts power from a mechanical rotational network and delivers it to a hydraulic (isothermal liquid) network. The pump displacement varies in proportion to the physical signal specified at port C or D. The port used depends on the block variant selected. See Ports.

Ports T and P represent the pump inlet and outlet, respectively. Port S represents the pump drive shaft. During normal operation, the pressure gain from port T to port P is positive if the angular velocity at port S is positive also. This operation mode is referred to here as forward pump.

Operation Modes

Four operation modes are possible. The working mode depends on the pressure gain from port T to port P (Δp), the angular velocity at port S (ω), and the instantaneous displacement input at port D (D). The Operation Modes figure maps the modes to the octants of a Δp-ω-D chart. The modes are labeled 1–4:

  • Mode 1: forward pump — A positive shaft angular velocity generates a positive pressure gain.

  • Mode 2: reverse motor — A negative pressure drop (shown in the figure as a positive pressure gain) generates a negative shaft angular velocity.

  • Mode 3: reverse pump — A negative shaft angular velocity generates a negative pressure gain.

  • Mode 4: forward motor — A positive pressure drop (shown in the figure as a negative pressure gain) generates a positive shaft angular velocity.

The response time of the pump is considered negligible in comparison with the system response time. The pump is assumed to reach steady state nearly instantaneously and is treated as a quasi-steady component.

Block Variants and Loss Parameterizations

The pump model accounts for power losses due to leakage and friction. Leakage is internal and occurs between the pump inlet and outlet only. The block computes the leakage flow rate and friction torque using your choice of five loss parameterizations. You select a parameterization using block variants and, in the Analytical or tabulated data case, the Friction and leakage parameterization parameter.

Loss Parameterizations

The block provides three Simulink® variants to select from. To change the active block variant, right-click the block and select Simscape > Block choices. The available variants are:

  • Analytical or tabulated data — Obtain the mechanical and volumetric efficiencies or losses from analytical models based on nominal parameters or from tabulated data. Use the Friction and leakage parameterization parameter to select the exact input type.

  • Input efficiencies — Provide the mechanical and volumetric efficiencies directly through physical signal input ports.

  • Input losses — Provide the mechanical and volumetric losses directly through physical signal input ports. The mechanical loss is defined as the internal friction torque. The volumetric loss is defined as the internal leakage flow rate.

Displacement Parameterizations

The displacement volume input depends on the block variant selected. If the active block variant is Input efficiencies or Input losses, the block obtains the instantaneous displacement volume directly from the physical signal input at port D.

If the active block variant is Analytical or tabulated data, the block computes the instantaneous displacement volume from the control member position specified at port C. This computation depends on the Displacement parameterization parameter setting:

  • Maximum displacement and control member stroke — Compute the displacement volume per unit rotation as a linear function of the control member position specified at port C.

  • Displacement vs. control member position table — Compute the displacement volume per unit volume using interpolation or extrapolation of displacement tabular data specified at discrete control member positions.

Flow Rate and Driving Torque

The volumetric flow rate generated at the pump is

q=qIdealqLeak,

where:

  • q is the net volumetric flow rate.

  • qIdeal is the ideal volumetric flow rate.

  • qLeak is the internal leakage volumetric flow rate.

The driving torque required to power the pump is

τ=τIdeal+τFriction,

where:

  • τ is the net driving torque.

  • τIdeal is the ideal driving torque.

  • τFriction is the friction torque.

Ideal Flow Rate and Ideal Torque

The ideal volumetric flow rate is

qIdeal=DSat·ω,

and the ideal driving torque is

τIdeal=DSat·Δp,

where:

  • DSat is a smoothed displacement computed so as to remove numerical discontinuities between negative and positive displacements.

  • ω is the shaft angular velocity.

  • Δp is the pressure gain from inlet to outlet.

Saturation Displacement

The saturation displacement depends on the block variant selected. If the active variant is Analytical or tabulated data,

DSat={DMax,|D|DMaxD2+DThresh2,D0D2+DThresh2,D<0,

where:

  • D is the displacement computed from the control member position.

    DMax is the Maximum displacement parameter.

  • DThresh is the Displacement threshold for pump-motor transition parameter.

If the active variant is Input efficiencies or Input losses, there is no upper bound on the displacement input and the saturation displacement reduces to:

DSat={D2+DThresh2,D0D2+DThresh2,D<0.

Leakage Flow Rate and Friction Torque

The internal leakage flow rate and friction torque calculations depend on the block variant selected. If the block variant is Analytical or tabulated data, the calculations depend also on the Leakage and friction parameterization parameter setting. There are five possible permutations of block variant and parameterization settings.

Case 1: Analytical Efficiency Calculation

If the active block variant is Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Analytical, the leakage flow rate is

qLeak=KHPΔp,

and the friction torque is

τFriction=(τ0+KTP|Δp|)tanh(4ωωThresh)

where:

  • KHP is the Hagen-Poiseuille coefficient for laminar pipe flows. This coefficient is computed from the specified nominal parameters.

  • KTP is the Friction torque vs pressure gain coefficient parameter.

  • τ0 is the No-load torque parameter.

  • ωThresh is the threshold angular velocity for the pump-motor transition. The threshold angular velocity is an internally set fraction of the Nominal shaft angular velocity parameter.

The Hagen-Poiseuille coefficient is determined from nominal fluid and component parameters through the equation

KHP=νNomρvρNomωNomDMaxΔpNom(1ηv,Nom),

where:

  • νNom is the Nominal kinematic viscosity parameter. This is the kinematic viscosity at which the nominal volumetric efficiency is specified.

  • ρNom is the Nominal fluid density parameter. This is the density at which the nominal volumetric efficiency is specified.

  • ρ is the actual fluid density in the attached hydraulic (isothermal liquid) network. This density can differ from the Nominal fluid density parameter.

  • ωNom is the Nominal shaft angular velocity parameter. This is the angular velocity at which the nominal volumetric efficiency is specified.

  • v is the fluid kinematic viscosity in the attached hydraulic fluid network.

  • ΔpNom is the Nominal pressure gain parameter. This is the pressure gain at which the nominal volumetric efficiency is specified.

  • ηv,Nom is the Volumetric efficiency at nominal conditions parameter. This is the volumetric efficiency corresponding to the specified nominal conditions.

Case 2: Efficiency Tabulated Data

If the active block variant is Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical efficiencies, the leakage flow rate is

qLeak=qLeak,Pump(1+α)2+qLeak,Motor(1α)2

and the friction torque is

τFriction=τFriction,Pump1+α2+τFriction,Motor1α2

where:

  • α is a numerical smoothing parameter for the motor-pump transition.

  • qLeak,Pump is the leakage flow rate in pump mode.

  • qLeak,Motor is the leakage flow rate in motor mode.

  • τFriction,Pump is the friction torque in pump mode.

  • τFriction,Motor is the friction torque in motor mode.

The smoothing parameter α is given by the hyperbolic function

α=tanh(3ΔpΔpThresh)·tanh(3ωωThresh)·tanh(3DDThresh),

where:

  • ΔpThresh is the Pressure gain threshold for pump-motor transition parameter.

  • ωThresh is the Angular velocity threshold for pump-motor transition.

The leakage flow rate is computed from efficiency tabulated data through the equation

qLeak,Pump=(1ηv)qIdeal

in pump mode and through the equation

qLeak,Motor=(1ηv)q

in motor mode, where:

  • ηv is the volumetric efficiency obtained through interpolation or extrapolation of the Volumetric efficiency table, e_v(dp,w,D) parameter data.

Similarly, the friction torque is computed from efficiency tabulated data through the equation

τFriction,Pump=(1ηm)τ

in pump mode and through the equation

τFriction,Motor=(1ηm)τIdeal

in motor mode, where:

  • ηm is the mechanical efficiency obtained through interpolation or extrapolation of the Mechanical efficiency table, e_m(dp,w,D) parameter data.

Case 3: Loss Tabulated Data

If the active block variant is Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical losses, the leakage flow rate equation is

qLeak=qLeak(Δp,ω,DSat)

and the friction torque equation is

τFriction=τFriction(Δp,ω,DSat)

where qLeak(Δp,ω,DSat) and τFriction(Δp,ω,DSat) are the volumetric and mechanical losses, obtained through interpolation or extrapolation of the Volumetric loss table, q_loss(dp,w,D) and Mechanical loss table, torque_loss (dp,w,D) parameter data.

Case 4: Efficiency Physical Signal Inputs

If the active block variant is Input efficiencies, the leakage flow rate and friction torque calculations are as described for efficiency tabulated data (case 2). The volumetric and mechanical efficiency lookup tables are replaced with physical signal inputs that you specify through ports EV and EM.

Case 5: Loss Physical Signal Inputs

If the block variant is Input losses, the leakage flow rate and friction torque calculations are as described for loss tabulated data (case 3). The volumetric and mechanical loss lookup tables are replaced with physical signal inputs that you specify through ports LV and LM.

Assumptions

  • Fluid compressibility is negligible.

  • Loading on the motor shaft due to inertia, friction, and spring forces is negligible.

Ports

Input

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Physical signal input port for the control member offset. The input signal is in units of m. The block maps the control member offset to a displacement volume using the tabulated data specified in the block dialog box.

Dependencies

This port is exposed only when the block variant is set to Analytical or tabulated data.

Physical signal input port for the displacement volume per unit rotation. The input signal is in units of cm^3/rev. It has a saturation bound at the Displacement threshold for pump-motor transition parameter value.

Dependencies

This port is exposed only when the block variant is set to Input efficiencies or Input losses.

Physical signal input port for the volumetric efficiency coefficient. The input signal is a unitless number with upper and lower bounds at the specified Maximum volumetric efficiency and Minimum volumetric efficiency parameter values.

Dependencies

This port is exposed only when the block variant is set to Input efficiencies.

Physical signal input port for the mechanical efficiency coefficient. The input signal is a unitless number with upper and lower bounds at the specified Maximum mechanical efficiency and Minimum mechanical efficiency parameter values.

Dependencies

This port is exposed only when the block variant is set to Input efficiencies.

Physical signal input port for the volumetric loss coefficient. The input signal expresses the leakage flow rate in units of m^3/s.

Dependencies

This port is exposed only when the block variant is set to Input losses.

Physical signal input port for the mechanical loss coefficient. The input signal expresses the friction torque in units of N*m.

Dependencies

This port is exposed only when the block variant is set to Input losses.

Conserving

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Hydraulic (isothermal liquid) conserving port representing the pump outlet.

Hydraulic (isothermal liquid) conserving port representing the pump inlet.

Mechanical rotational conserving port representing the pump shaft.

Parameters

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The exposed block parameters depend on the active block variant. See Block Variants and Loss Parameterizations.

Variable 1: Analytical or tabulated data

Parameterization used to convert the physical signal at input port C to an instantaneous displacement:

  • Maximum displacement and control member stroke — Compute the displacement as a linear function of the control position specified at port C.

  • Displacement vs. control member position table — Obtain the displacement through interpolation or extrapolation of tabulated data specified over a range of control positions.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data.

Restricted Parameter

This parameter is locked for editing when using the Simscape™ Restricted mode.

Control position corresponding to a maximum displacement. The physical signal input at port C saturates at this value. If the input rises higher, the block sets the control position to the maximum stroke.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data.

Maximum fluid volume swept per unit shaft rotation. The displacement reaches this value when the control position hits the maximum stroke.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Displacement parameterization parameter is set to Maximum displacement and control member stroke.

M-element vector of control positions at which to specify the instantaneous displacement. The vector size, M, must be two or greater. The vector elements need not be uniformly spaced. However, they must be monotonically increasing or decreasing.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Displacement parameterization parameter is set to Displacement vs. control member position table.

M-element vector with the displacement tabular data for the specified control positions. The vector size, M, must match that of the Control member position vector parameter.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Displacement parameterization parameter is set to Displacement vs. control member position table.

Numerical technique used to map control position signals to displacements within the tabular date range. The interpolation method joins tabular data points using straight or curved line segments. Displacements within the range of the tabular data are assumed to lie on these segments.

  • Linear — Join neighboring data points using straight line segments. Line slopes are generally discontinuous at the line segment end points.

  • Smooth — Join neighboring data points using curved line segments generated with a modified Akima algorithm. Line slopes are continuous at the line segment end points.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Displacement parameterization parameter is set to Displacement vs. control member position table.

Restricted Parameter

This parameter is locked for editing when using the Simscape Restricted mode.

Numerical technique used to map control position signals to displacements outside the tabular date range. The extrapolation method extends the first and last tabular data points outward using horizontal or sloped straight line segments. Displacements outside the range of the tabular data are assumed to lie on these segments.

  • Linear — Extend the tabular data using sloped straight line segments. The line slopes are computed from the first and last two tabular data points.

  • Nearest — Extend the tabular data using horizontal straight line segments. The lines correspond to the displacements specified in the first and last tabular data points.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Displacement parameterization parameter is set to Displacement vs. control member position table.

Restricted Parameter

This parameter is locked for editing when using the Simscape Restricted mode.

Parameterization used to compute flow-rate and torque losses due to internal leaks and friction. The Analytical parameterization relies on nominal parameters generally available from component data sheets. The remaining, tabular, options rely on lookup tables to map pressure drop, angular velocity, and displacement to component efficiencies or losses. The tabular options include:

  • Tabulated data — volumetric and mechanical efficiencies

  • Tabulated data — volumetric and mechanical losses

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data.

Angular velocity of the rotating shaft at which the component's nominal volumetric efficiency is known. Nominal parameters are typically published for standard operating conditions in manufacturer's data sheets. The block uses this parameter to calculate, using simple linear functions, the leakage flow rate and friction torque.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Analytical.

Pressure gain from inlet to outlet at which the component's nominal volumetric efficiency is known. Nominal parameters are typically published for standard operating conditions in manufacturer's data sheets. The block uses this parameter to calculate, using a simple linear function, the internal leakage flow rate.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Analytical.

Kinematic viscosity of the hydraulic fluid at which the component's nominal volumetric efficiency is known. Nominal parameters are typically published for standard operating conditions in manufacturer's data sheets. The block uses this parameter to calculate, using a simple linear function, the internal leakage flow rate.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Analytical.

Mass density of the hydraulic fluid at which the component's nominal volumetric efficiency is known. Nominal parameters are typically published for standard operating conditions in manufacturer's data sheets. The block uses this parameter to calculate, using a simple linear function, the internal leakage flow rate.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Analytical.

Volumetric efficiency, defined as the ratio of actual to ideal volumetric flow rates, at the specified nominal conditions. Nominal parameters are typically published for standard operating conditions in manufacturer's data sheets. The block uses this parameter to calculate, using a simple linear function, the internal leakage flow rate.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Analytical.

Torque required to overcome seal friction and induce rotation of the mechanical shaft. This torque is the load-independent component of the total friction torque.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Analytical.

Proportionality constant at maximum displacement between the friction torque on the mechanical shaft and the pressure gain from inlet to outlet.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical efficiencies.

Absolute value of the instantaneous displacement below which the component transitions between pumping and motoring modes. A hyperbolic Tanh function transforms the leakage flow rate and friction torque such that the transition is continuous and smooth.

Simulation warning mode for invalid pressures at the component ports. Select Warning to be notified when pressure falls below a minimum specified value. The warning can be useful in models where pressure can fall below the saturated vapor pressure of the hydraulic fluid, causing cavitation to occur.

Lower bound of the pressure validity range. A warning is issued if pressure falls below the specified value.

Dependencies

This parameter is enabled when the Check if lower side pressure violating minimum valid condition parameter is set to Warning.

M-element vector of pressure gains at which to specify the efficiency tabular data. The vector size, M, must be two or greater. The vector elements need not be uniformly spaced. However, they must monotonically increase in value from left to right.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical efficiencies.

N-element vector of shaft angular velocities at which to specify the efficiency tabular data. The vector size, N, must be two or greater. The vector elements need not be uniformly spaced. However, they must monotonically increase in value from left to right.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical efficiencies.

L-element vector of displacements at which to specify the efficiency tabular data. The vector size, N, must be two or greater. The vector elements need not be uniformly spaced. However, they must be monotonically increasing or decreasing.

M-by-N-by-L matrix with the volumetric efficiencies at the specified fluid pressure gains, shaft angular velocities, and displacements. The efficiencies must fall in the range of 0–1. M, N, and L are the sizes of the specified lookup-table vectors:

  • M is the number of vector elements in the Pressure gain vector for efficiencies, dp parameter.

  • N is the number of vector elements in the Shaft angular velocity vector for efficiencies, w parameter.

  • D is the number of vector elements in the Displacement vector for efficiencies, D parameter.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical efficiencies.

M-by-N-by-L matrix with the mechanical efficiencies corresponding to the specified fluid pressure gains, shaft angular velocities, and displacements. The efficiencies must fall in the range of 0–1. M, N, and L are the sizes of the specified lookup-table vectors:

  • M is the number of vector elements in the Pressure gain vector for efficiencies, dp parameter.

  • N is the number of vector elements in the Shaft angular velocity vector for efficiencies, w parameter.

  • D is the number of vector elements in the Displacement vector for efficiencies, D parameter.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical efficiencies.

Pressure gain from inlet to outlet below which the component begins to transition between motoring and pumping modes. A hyperbolic Tanh function transforms the leakage flow rate and friction torque such that the transition is continuous and smooth.

Dependencies

This parameter is enabled when the block variant is set to Input efficiencies or when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical efficiencies.

Shaft angular velocity below which the component begins to transition between motoring and pumping modes. A hyperbolic Tanh function transforms the leakage flow rate and friction torque such that the transition is continuous and smooth.

Dependencies

This parameter is enabled when the block variant is set to Input efficiencies or when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical efficiencies.

Simulation warning mode for operating conditions outside the range of tabulated data. Select Warning to be notified when the fluid pressure gain, shaft angular velocity, or instantaneous displacement cross outside the specified tabular data. The warning does not cause simulation to stop.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical efficiencies or Tabulated data — volumetric and mechanical losses.

M-element vector of pressure gains at which to specify the loss tabular data. The vector size, M, must be two or greater. The vector elements need not be uniformly spaced. However, they must monotonically increase in value from left to right.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical losses.

N-element vector of shaft angular velocities at which to specify the efficiency tabular data. The vector size, N, must be two or greater. The vector elements need not be uniformly spaced. However, they must monotonically increase in value from left to right.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical losses.

L-element vector of displacements at which to specify the loss tabular data. The vector size, N, must be two or greater. The vector elements need not be uniformly spaced. However, they must be monotonically increasing or decreasing.

M-by-N-by-L matrix with the volumetric gains at the specified fluid pressure drops, shaft angular velocities, and displacements. Volumetric loss is defined here as the internal leakage volumetric flow rate between port A and port B. M, N, and L are the sizes of the specified lookup-table vectors:

  • M is the number of vector elements in the Pressure gain vector for losses, dp parameter.

  • N is the number of vector elements in the Shaft angular velocity vector for losses, w parameter.

  • D is the number of vector elements in the Displacement vector for losses, D parameter.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical losses.

M-by-N-by-L matrix with the mechanical losses at the specified fluid pressure gains, shaft angular velocities, and displacements. Mechanical loss is defined here as the friction torque due to seals and internal components. M, N, and L are the sizes of the specified lookup-table vectors:

  • M is the number of vector elements in the Pressure gain vector for losses, dp parameter.

  • N is the number of vector elements in the Shaft angular velocity vector for losses, w parameter.

  • D is the number of vector elements in the Displacement vector for losses, D parameter.

Dependencies

This parameter is enabled when the block variant is set to Analytical or tabulated data and the Leakage and friction parameterization parameter is set to Tabulated data — volumetric and mechanical losses.

Variant 2: Input efficiencies

Pressure gain from inlet to outlet below which the component begins to transition between motoring and pumping modes. A hyperbolic Tanh function transforms the leakage flow rate and friction torque such that the transition is continuous and smooth.

Dependencies

This parameter is enabled when the block variant is set to Input efficiencies.

Shaft angular velocity below which the component begins to transition between motoring and pumping modes. A hyperbolic Tanh function transforms the leakage flow rate and friction torque such that the transition is continuous and smooth.

Dependencies

This parameter is enabled when the block variant is set to Input efficiencies.

Absolute value of the instantaneous displacement below which the component transitions between motoring and pumping modes. A hyperbolic Tanh function transforms the leakage flow rate and friction torque such that the transition is continuous and smooth.

Smallest allowed value of the volumetric efficiency. The input from physical signal port EV saturates at the specified value. If the input signal falls below the minimum volumetric efficiency, the volumetric efficiency is set to the minimum volumetric efficiency.

Dependencies

This parameter is enabled when the block variant is set to Input efficiencies.

Largest allowed value of the volumetric efficiency. The input from physical signal port EV saturates at the specified value. If the input signal rises above the maximum volumetric efficiency, the volumetric efficiency is set to the maximum volumetric efficiency.

Dependencies

This parameter is enabled when the block variant is set to Input efficiencies.

Smallest allowed value of the mechanical efficiency. The input from physical signal port EM saturates at the specified value. If the input signal falls below the minimum mechanical efficiency, the mechanical efficiency is set to the minimum mechanical efficiency.

Dependencies

This parameter is enabled when the block variant is set to Input efficiencies.

Largest allowed value of the mechanical efficiency. The input from physical signal port EM saturates at the specified value. If the input signal rises above the maximum mechanical efficiency, the mechanical efficiency is set to the maximum mechanical efficiency.

Dependencies

This parameter is enabled when the block variant is set to Input efficiencies.

Simulation warning mode for invalid pressures at the component ports. Select Warning to be notified when pressure falls below a minimum specified value. The warning can be useful in models where pressure can fall below the saturated vapor pressure of the hydraulic fluid, causing cavitation to occur.

Lower bound of the pressure validity range. A warning is issued if pressure falls below the specified value.

Dependencies

This parameter is enabled when the Check if lower side pressure violating minimum valid condition parameter is set to Warning.

Variant 3: Input losses

Absolute value of the instantaneous displacement below which the component transitions between pumping and motoring modes. A hyperbolic Tanh function transforms the leakage flow rate and friction torque such that the transition is continuous and smooth.

Simulation warning mode for operating conditions outside the pumping mode. A warning is issued if the pump transitions to motoring mode. Select Warning to be notified when this transition occurs. The warning does not cause simulation to stop.

Dependencies

This parameter is enabled when the block variant is set to Input losses.

Simulation warning mode for invalid pressures at the component ports. Select Warning to be notified when pressure falls below a minimum specified value. The warning can be useful in models where pressure can fall below the saturated vapor pressure of the hydraulic fluid, causing cavitation to occur.

Lower bound of the pressure validity range. A warning is issued if pressure falls below the specified value.

Dependencies

This parameter is enabled when the Check if lower side pressure violating minimum valid condition parameter is set to Warning.

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