Abstract: As one of the essential components of intelligent four-wheel drive, transfer case has been studied thoroughly in the area of mechanical drive in the past. However, its friction heat during the transmission of power is rarely discussed. In our works, we construct a model of transfer case based on heat load characteristics. Then, a performance simulation model in Matlab/Simulink is built, which shows that heat load has a great impact on frictional coefficient and viscosity of lubricating oil of transfer case. Based on the above inspection, a test platform for transfer case is constructed, and we find out that the relation between total torque and torque response time under heat load is consistent with the theoretical result. The peak viscous torque is one thirds of the peak total torque, and it costs about 0.3 seconds to reach the peak total torque. The number of friction plate and the pressure play major roles to determine transferable torque. The widths of sumps, while affect viscous torque greatly, do not affect asperity torque as much. The difference between transferable torques of transfer case with and without trenches under heat load is analyzed, and we find the important role of heat load in the working process of transfer case and how its operating characteristic varies during connecting process, which can provides a theoretical basis for the designing of transfer case.

Key words: experimental test, multi-plate clutch, power transfer, thermal load, transfer case