Abstract
Keywords - Manual Transmission, Idling Rattle, Subharmonic Vibration, Computer Simulation, Clutch
Abstract - By the results of computer simulation performed on idling rattle of a manual transmission with five to three degrees of freedom system and with only one idler gear with equivalent inertia, the followings have been clarified. (1) 1/2 and 1/3 order subharmonic vibrations are generated by nonlinear torsional characteristics of the clutch disc, and they make the idling rattle larger because of the increase in tooth collision force between the idler and driven shaft gears. (2) Both the drag torque and the torsional characteristics of the clutch disc have effects on 1/2 and 1/3 order subharmonic vibrations, and the backlash between idler and driven shaft gears have no effects on the vibrations. (3) 1/2 and 1/3 order subharmonic vibrations are caused by single-sided impact from the first-stage to the second-stage of the torsional characteristics of the clutch disc.
In order to reduce idling rattle below a certain level in a wide range of transmission oil temperature, it is necessary to allow both subharmonic vibrations at low oil temperature and fundamental harmonic vibrations at high oil temperature. In order to realize the reduction, it is necessary to select clutch characteristics that allow the operating angle to enter the second stage at low oil temperature.