Chatter Causes and Solutions Schaeffler Group（舍弗勒集团喋喋不休原因和解决方案）.pdf

Chatter - Causes and Solutions Prof. Dr.-Ing. Albert Albers Dipl.-Ing. Daniel Herbst Definition of Chatter Vibrations that arise during the slip phase of the clutch in the drive train of a motor vehicle and are generated in the clutch area should by definition be included under chatter. This definition is consciously kept general; it makes no statement on the causes of the vibrations. It is also used by other authors [1]. With an engaged clutch, the drive train can also vibrate in a frequency range similar to a true chatter. This “pseudo-chatter” can be caused by extreme lagging, defective engine mounts or a clunk in engagement and is often mistaken for true chatter. Causes and Manifestations of Chatter Chatter is caused when a periodic torque change is generated in a slipping clutch, whose natural frequency range is similar to that of the drive train dynamically separated from the clutch. The first natural frequency of passenger car drive trains is between 8 and 12 Hz under these conditions and thus with an engine speed of approximately 480 to 720 rpm (with a 1st order of excitation). The drive wheels convert the rotating vibrations of the drive train to a longitudinal vibration of the vehicle. The chatter is expressed as a vibration in the longitudinal direction of the vehicle and is transferred via the operating elements and driver’s seat. The driver senses unpleasant vibrations (see Figure 1), which can also be connected to noises. In the resonance range, even the smallest excitation amplitudes are enough to cause strong vibrations in the drive train. Hence, for example, certain drive trains with a maximum transferable clutch torque of 500 Nm can excite vibration amplitudes