Research On Powertrain Trade-off Of The Heavy Commercial Vehicle

With the development of automobile industry and the consciousness of environmental protection becoming strengthened,higher demands are brought forward for automobile drive ability,economy and emission performance.In China,manufacturing is divided so detailed that engines and chassis are often made from different factories.So how to fulfill the best compatible between engine and chassis to make the automobile own better drive ability,economical and emission performance become very important in the process of studying the match of the vehicle.Driving performance and fuel economy not only depend on the engine performance,but also on the transmission parameters selection and the power train matching.Engine and power train are two important elements,which are fetal to the normal running.The matching between them will directly affect the performance and fuel economy.The Truck transmission parameters should be optimized to make the engine work almost in the low-fuel consumption region when it operates in the real driving modes.Overseas study on model formulation and the software development work of automobile dynamic property and the fuel economy began from the1960s.In China,the study on the aspect is later than the other countries and began from the late1980s.However,early research is not adopt to the rapid development of automotive technology,thus further research on this aspect is necessary.The following aspects will be studied.Referring to the research all over the world,the paper establishes the evaluating index of dynamic property and fuel economy,as well as entire automobile integrative evaluating index,which includ loss ratio of driving power,constant speed fuel consumption of100km,the fuel consumption of circulation test and energy utilization ratio.Mathematics model of engine-torque characteristic and engine mapping characteristics is established. Transmission efficency model of transmission and driving axle and shifting mode of the dynamic property and fuel economy are established,which make the results of simulation much more veracious. According to the theory of vehicle and the test requirement of National Standard on fuel economy and dynamic property,the simulation method of dynamic property and the fuel economy of the heavy duty truck is established. After establishment the driving cycle of the vehicle,which can represent the real-word drving conditon of the truck,in order to establish the vehicle model as accuately as possible,the advance simulation software-AVL-CRUISE is used to establish the vehicle model.AVL-CRUISE is designed specially for matching engines and chassis and then it can calculate the performance of vehicles.All of the calculation model have passed experiments test,so the results of the calculation is precise and reliable.This paper introduces the main function,application scope,and operation course of AVL-CRUISE,also including the introduction of elements.Based on the manufacture mode of the heavy-duty truck,the paper puts forward to a sort of methods solving how to choose the powertrain for better automobile characteristics,including how to choose engine type,maximum engine power,engine peak speed,maximum engine torque,transmission ratio and driving. Besides the powertrain,there are lots of factors that affect the dynamic property and fuel economy of the heavy duty truck,such as gross weight,rolling resistance coefficient,drag factor,windward area,drive-train efficiency,and so on.