Effect of normal load evolution on transient torsional vibrations during clutch engagement

• Different models of the evolving normal load in the clutch friction interface and their respective influence on friction induced torsional driveline vibrations, during clutch engagement, are examined. This is done in the context of driveline vibrations of heavy duty vehicles with combustion engines. In prior studies of clutch synchronisation a lot of focus has been devoted to the characteristics of the coefficient of friction. A negative gradient of the coefficient of friction, with respect to slipspeed, can lead to driveline instabilities, sometimes referred to as clutch start-up judder. However, the way in which the normal load evolves, and consequently how the friction torque builds up during synchronization, has been given less attention. This study compares the influence of a linear evolution of the normal load to a quadratic evolution. It is shown that the slope of the normal load at the beginning of synchronization is pivotal to the excitation of driveline vibrations, where a decrease of the slope effectively reduces the self-excited vibrations.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Tribologi (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Tribology (hsv//eng)

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