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Variable Displacement Motor

Variable displacement motor/pump with mechanical and volumetric efficiency maps

 

Description

Data Source Option

Connections

Parameters

Description

The Variable Displacement Motor and Variable Displacement Pump are identical devices that can be used as either a motor or pump.

Data Source Option

The mechanical and volumetric efficiency of the motor can be set to a constant or computed based on its dependencies. When the variation is constant the ηmech and ηvol given by the user are used in calculations. When specifying the variation as a function of pressure difference and displacement or as a function of speed and pressure difference, any one of the below mentioned Data source options can be selected:

– 

Data Source: This parameter allows users to specify the nature of the source file table. The available options are file, attachment, and inline.

• 

file: Use this option to specify a source file (an Excel or a CSV file) located on the hard drive. Use the ηmech and ηvol parameter dropdown menus to browse and/or select a data file. The data file will not be attached to the MapleSim model.

• 

attachment: Use this option to specify a data file (an Excel or a CSV file) that is attached to the MapleSim model. To be used as an attachment, data files must be attached to the MapleSim model and be categorized under Data Sets. The attached files in a MapleSim model can be viewed In the Attachments pane under the Data Sets section. For more information, see Attaching a File to a Model. If the required file is not already attached to the MapleSim model, use the ηmech and ηvol parameter dropdown menus to attach a new file.

Note:

• 

If the file option is used, subsequent changes to the source file will be reflected in MapleSim simulations

• 

If the attachment option is used, subsequent changes to the source file will not affect the version attached to the MapleSim model. To ensure updates to the source files are reflected in the simulation, the file must be reattached.

• 

The Data Generation App can be used to generate table data from mathematical functions using Maple code. For more information about MapleSim apps, see Opening MapleSim Apps and Templates.

• 

inline: Use this option to directly specify the ηmech and ηvol values as a function of the quantities listed in the Variation dropdown menu. The data is entered in the form of a table.

Note: To change the dimensions of the table, right-click (Control-click for Mac®) the parameter field and select Edit Matrix Dimensions. In the Matrix Dimensions dialog, enter values for the number or rows and columns and then click OK.

The data specified by the options mentioned above must conform to the following formatting:

• 

In an m×n matrix A, the elements 2 through m of the first column contain the values of the first quantity listed in the Variation dropdown menu.

– 

In an m×nn matrix A, the elements 2 through n of the first row contain the values of the second quantity listed in the Variation dropdown menu.

– 

The values of the dependent quantity (ηmech, ηvol) are specified in the remaining elements of the matrix. The entry Aij corresponds to the value of ηmech, ηvol for the i-th value of the first quantity listed in the Variation dropdown menu and the j-th value of the second quantity listed in the Variation dropdown menu.

– 

Skip rows: This option allows users to specify the number of top rows to be ignored during the calculations. This option can be useful when the Excel file contains header information.

– 

Smooth: The smooth option allows to specify how the data table is interpolated.

– 

Pressure difference unit: This option allows users to select the unit of pressure used in the supplied data.

– 

Disp unit: This option allows users to select the unit of displacement used in the supplied data.

Connections

Name

Description

Modelica ID

portA

Upstream hydraulic port

portA

portB

Downstream hydraulic port

portB

disp

Optional real input; commanded displacement per revolution

disp

flangeb

Right flange of compliant 1-dim. rotational component

flange_b

Parameters

Data Units Parameters

Name

Default

Units

Description

Modelica ID

Pressure difference unit

kPa

 

Unit for pressure data

pressUnit

Angular velocity unit

rpm

 

Unit for angular velocity data

speedUnit

Disp. unit

cm3

 

Unit for displacement data

dispUnit

Displacement Parameters

Name

Default

Units

Description

Modelica ID

Use variable displacement

false

 

True means enable disp input

useVariableDisplacement

D

1·10−4

m3

Constant displacement per revolution

D

Dmax

1·10−4

m3

Maximum displacement per revolution

Dmax

Disp. input unit

cm3

 

Unit for displacement data

dispInUnit

Mechanical Efficiency Parameters

Name

Default

Units

Description

Modelica ID

Variation

constant

 

Efficiency parametrization

paramType1

ηmech

1

 

Constant mechanical efficiency. Use values between 0 and 1.

MechEff

Data source

inline

 

Data source

datasourcemode1

ηmech

[0,0.5,1; 0.5,0.9,0.9; 1,0.9,0.9]

 

Data set

table1

Smooth

linear segments

 

Smoothness of table interpolation

smoothness1

Motor/Pump Switching Parameters

Name

Default

Units

Description

Modelica ID

Pressure difference threshold

1·104

Pa

Motor/Pump switching threshold

pressThreshold

Angular velocity threshold

π3

rads

Motor/Pump switching threshold

speedThreshold

Disp. threshold

1·10−7

m3

Motor/Pump switching threshold

dispThreshold

TPM

0.001

s

Motor/Pump switching time constant

TPM

Volumetric Efficiency Parameters

Name

Default

Units

Description

Modelica ID

Variation

1

 

Efficiency parametrization

paramType2

ηvol

1

 

Constant mechanical efficiency. Use values between 0 and 1.

VolEff

Data source

inline

 

Data source

datasourcemode2

ηvol

[0,0.5,1; 0.5,0.9,0.9; 1,0.9,0.9]

 

Data set

table2

ηvol

 

 

Attached Data Set

data2

Smooth

linear segments

 

Smoothness of table interpolation

smoothness2

See Also

Hydraulics Library

Rotary Actuators