A Study on the Effects of Shifting Frequency upon Average Temperature Rise of Clutches

A model for calculating the frequency of gear shifting of a tracked vehicle is set up with consideration of road resistance coefficients, to analyze the shifting frequency with different gears in a hundred kilometer straight driving in different regions. An average temperature rise model for the hydraulic system of shifting clutches is modified based on lumped heat resistance network theory and a Simulink simulation is conducted to analyze the effects of shifting frequency and cooling lubricant flow rate on the temperature rise of clutches. The results of comparison between simulation and bench test show that the simulation results with modified model is closer to test ones, temperature rise rate reduces with the increase of lubricant flow rate, and for the study object in this paper, the appropriate lubricant flow rate for single friction pair should be in the range of 1.5~2L/min, and the temperature rises when shifting frequency increases. By comparatively analyzing the effects of shifting frequency on the temperature rise of clutches in plain, plateau and hot-humid regions, a predicted relationship between temperature rise and shifting frequency is fitted. In plain and plateau regions, the highest shifting frequency occurs between 3rd gear and 4th gear, with more temperature rises in clutches CL and CH, while in hot-humid regions, the shifting between 2nd rear and 3rd gear is most frequent, with the temperature rises in four shifting clutches all as high as up to 82.9℃.