Clutch

Series connection of freewheel and clutch

Library

Mechanics/Rotational/Components

Description

This component models a clutch, i.e., a component with two flanges where friction is present between the two flanges and these flanges are pressed together via a normal force. The normal force fn has to be provided as input signal f_normalized (top) in a normalized form (0 <= f_normalized <= 1), fn = fn_max * f_normalized, where fn_max has to be provided as parameter. Friction in the clutch is modelled as COULOMB friction.

When the relative angular velocity between the flanges is not zero, the friction torque is a function of the friction coefficient mue_pos , of the normal force fn, and of a geometry constant cgeo which takes into account the geometry of the device and the assumptions on the friction distribution:

    friction_torque = cgeo * mue0 * fn .

When the relative angular velocity becomes zero, the elements connected by the friction element become stuck, i.e., the relative angle between the flanges remains constant. In this phase the friction torque is calculated from a torque balance due to the requirement, that the relative acceleration shall be zero. The elements begin to slide when the friction torque exceeds a threshold value, called the maximum static friction (stiction) torque, computed as

    stiction_torque = peak * cgeo * mue_pos * fn ,

where peak >= 1 is another parameter to be defined by the user.

Parameters

    Clutch_0

  • mue_pos [-] : mue &gt; 0, positive sliding friction coefficient (w_rel&gt;=0) (mue_pos): Scalar.
  • peak [-] : peak &gt;= 1, peak*mue_pos = maximum value of mue for w_rel==0 (peak): Scalar.
  • cgeo [-] : cgeo &gt;= 0, Geometry constant containing friction distribution assumption (cgeo): Scalar.
  • fn_max [N] : fn_max &gt;= 0, Maximum normal force (fn_max): Scalar.
  • mode_start [-] : Initial sliding mode (-1=Backward,0=Sticking,1=Forward,2=Free) (mode_start): Scalar.

Ports

  • Port 1 at left position: implicit input fixedport numbered 1.
  • Port 1 at top position: implicit input fixedport numbered 2.
  • Port 1 at right position: implicit output fixedport numbered 1.

See Also