Gear with mesh efficiency and bearing friction (stuck/rolling possible)
Modelica Standard Library
The Lossy Gear component models the gear ratio and the losses of a standard gear box in a realistic way, including the stuck phases that may occur at zero speed. The gear boxes that can be handled are fixed in the ground or on a moving support, have one input and one output shaft, and are essentially described by the equations
where r is constant gear ratio, ηmf is the efficiency due to mesh friction, and τbf is the bearing friction torque.
The Loss Table parameter is five-column table that defines the loss terms ηmf and τbf in terms of the absolute value of the input shaft speed, wa, and of the energy flow direction. Its columns are |wa|,ηmf1,ηmf2,τbf1,τbf2 with
Angular speed of flangea
Mesh efficiency when input shaft is driving
Mesh efficiency when output shaft is driving
Absolute bearing friction torque when input shaft is driving
Absolute bearing friction torque when output shaft is driving
The rows of the Loss Table are ordered according to ωa, with the first row having the smallest ωa. The values for ηmf1, ηmf2, τbf1, and τbf2 at a particular shaft speed are interpolated from the values in the table.
To add rows to the table, right-click on the value and select Edit Matrix Dimension.
With these variables, the mesh efficiency and the bearing friction are formally defined as
Losses are modeled in a physically meaningful way taking into account that at zero speed the movement may be locked due to the friction in the gear teeth and/or in the bearings.
Absolute angle of flangex,x∈a,b
Absolute angle of support flange
Torque applied to flangex,x∈a,b
Flange of left shaft
Flange of right shaft
Conditional Support Flange
Optional heat port
Transmission ratio (φaφb)
Matrix for mesh efficiencies and bearing friction depending on speed
Use Heat Port
True (checked) means heat port is enabled
Use Support Flange
True (checked) enables the support flange
Value of mode is not known
Element is not active
w_a > 0 (forward rolling)
w_a = 0 (forward rolling, locked or backward rolling)
w_a < 0 (backward rolling)
The component described in this topic is from the Modelica Standard Library. To view the original documentation, which includes author and copyright information, click here.
1-D Mechanical Overview
Rotational Bearings and Gears
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