Parameters Optimization Of The Heavy-duty Vehicle Transmission Based On Reducing AMT Shifting Power Loss

As one of the main means of transport,heavy-duty truck plays an important role in today's society, and it is demanded more and more from its user. It is not only with optimum dynamic properties, but also with good fuel economy and emission. Research shows that the dynamic property, fuel economy,and emission could be improved greatly by rational optimization of the engine and transmission match.AMT could be classified as non-power shift automatic transmission, for the clutch has to be released before shifting. The clutch then engages again after shifting, As a result, the output power is interrupted inevitably during the shifting process. This not only has negative influence on riding comfort, but also leads to power loss. Because of relatively big mess of heavy-duty truck, its power loss during shifting process is relatively large too. When truck travelling on comprehensive pavement, the accumulated power loss will be even larger for the truck needs frequently shifting, which would affect the dynamic property, economical efficiency and its emission. The life span of clutch and synchronizer could be decreased either. For these reasons, the power loss of AMT during shifting must be considered when optimizing the parameters of AMT transmission.In this paper, the heavy-duty truck AMT transmission was taken as study object to optimize the parameters of heavy-duty truck transmission by considering the dynamic property, fuel economy and the power loss during shifting of heavy-duty truck. The optimized performance indexes were then compared with performance indexes of entire vehicle without optimization,validation study method is reasonable.This paper mainly includes the following.1. The developing condition of optimizing and matching transmission parameters of heavy vehicle at domestic and abroad was analyzed; 2. The processes of AMT shifting, clutch engaging and synchronizer engaging were analyzed, and the main power loss of AMT shifting process was studied;3. In connection with one heavy-duty truck's transmission, the models of entire car dynamic property and fuel economy were established by using MATLAB/SIMULINK based on automobile theory;4. The dynamic property and fuel economy of original car were simulated by using the established models and the original car's parameters. The simulations showed that the top speed, dynamic factor and climbing gradient met the need of the actual requirement. However, its fuel economy needed further improving. The simulations were compared with original car test, and the models were verified;5. Based on the power loss during AMT shifting process, the transmission parameters were optimized by considering the entire car dynamic property and fuel economy. The dynamic indexes of entire car dropped a little after the optimization. However, the fuel consumption of six working conditions was decreased which indicated that the fuel economy was improved at certain level. In the meantime, the power loss during AMT shifting decreased considerably. The conclusion showed that the optimization had considerable positive effect.The study of this paper has certain referential value and practical significance on further study on improving the transmission performance of heavy-duty truck AMT and its power loss during shifting process.