Research On Dynamic Performance Test Method Of Commercial Vehicle Based On Virtual Vehicle Test Bench

The most basic and important performance of automobile is dynamic performance.With the rapid development of transportation industry,commercial vehicles have gradually become the main means of freight transportation in China.The current dynamic performance testing standard is GB/T18276-2017 Test-bed Methods and Evaluating Index of Dynamic Property for Motor Vehicles.Compared with the original standard,there is not much change.With the development of the automotive industry and the iterative updating of technology,this standard can no longer meet the needs of dynamic testing.Therefore,based on the virtual vehicle test bed,this paper explores the dynamic performance of commercial vehicles from static to dynamic,besides,it closely follows the leading edge of the diagnostic and testing techniques of commercial vehicles,adopting virtual prototyping technology to integrate “people,vehicles,roads and environment”.Firstly,this paper introduces the structure and detection principle of virtual vehicle test bed.According to the actual situation of commercial vehicles,taking into account the inertia of each component of the transmission system and the transmission relationship between them,derives the rotational mass coefficient of commercial vehicles and obtains a more perfect road resistance equation for commercial vehicles.In addition,this paper also analyzes the dynamics of commercial vehicles in the virtual vehicle test-bed,and deduces a mathematical model of the loading resistance of the virtual vehicle test bed.Secondly,this paper analyzes the deficiencies in GB/T18276-2017 Test-bed Methods and Evaluating Index of Dynamic Property for Motor Vehicles.According to GB/T18276-2017,the evaluation index of indoor dynamic performance is the output power of driving wheel or the stable speed of the wheel-side.Therefore,this paper proposes a more intuitive evaluation indexes for commercial vehicles,i.e.the maximum speed,maximum gradient and acceleration time.Thirdly,for the test and analysis of the key parameters of the virtual vehicle test bed,this paper first analyzes the advantages and disadvantages of the coasting method,uses the constant speed test method to test the parasitic drag torque of the test bed,and obtains the test bench parasitic drag by curve fitting.In addition,this paper explores the impact of the axial loading variation on the tire rolling radius,adopts the coasting method to test the rolling resistance coefficient of the test bed and emphatically analyzes the change trend of the rolling resistance coefficient of the test bed with the speed under a certain load and air pressure.Finally,this paper conducted an indoor commercial vehicle dynamic test and verified the test results.Experimental data analysis results show the error between the bench test result at the highest speed and the road test result is-4.01%.Either in the bench test and road test of climbing steep slope or in the road test,this model can successfully pass 30% of the ramp.The fixed-gear acceleration performance bed test result at direct gear(40-70km/h)and the road test result have an error of-4.07%,and the error between the test result of top gear(50-80km/h)and the road test result is-3.3%.The results of bed test are basically consistent with the results of road test,which illustrates the accuracy of the dynamic model and dynamic test method in this paper.In the case that the prototype car has not yet been manufactured,this test method can still be used to test the dynamic performance of commercial vehicles indoors,which has a certain engineering application value.