A Method To Measure The Performance At The Automobile Transient Condition In Road Test

With the development and widely application of computational simulationtechnology, the time duration and costs of modern vehicle and powertraindevelopment have been significantly reduced. In this paper, the general trendsbetween the engine performance and the design as well as operational parameters arefirstly summarized based on secondary development of engine bench test data. Theengine performance parameters were then studies for the transient conditions in thevehicle road tests and a measurement method was proposed for the detection of engineperformance parameters, such as the instant torque output and fuel consumption rate,etc. under vehicle transient conditions, which is not possible up to now; In the sametime, vehicle road test data analysis and GT–Drive simulation are both utilized toverify the reliability and accuracy of the proposed method. Based on all the above aMicrosoft Excel-VBA based software platform is developed for real-time monitoringof the dynamic performance and instant fuel economy of the vehicle.Firstly, based on the fundamental kinematics theory, the relationship isestablished between the vehicle dynamical, and kinematical performance with engineperformance parameters, which constructs the theoretical basis for the detectionmethod. Then the rolling and air drag resistance coefficients are calculated from thevehicle coast down test results; At the same time, engine steady state bench tests areconducted, inner relationship between the engine performance, design and operationalparameters are summarized, and the general trends are developed, which forms thefoundation for the detection method of vehicle performance under transientconditions.Then, a full verification procedure is undergone for the proposed method. On theone hand, verification is conducted based on the experimental data from the variousvehicle road test data under transient condition; On the other hand, the widely usedGT-Drive software is utilized to establish a full vehicle model, vehicle performancedata under various steady state, dynamic and kinetic conditions are simulated andcompared to the test data. In this way the detection method is proved from theperspective of the simulation analysis.Finally, based on the Excel-VBA environment, this method is implemented into asoftware platform. And use the established real-time monitoring platform software of vehicle performance to monitor the vehicle road transient test, obtained thecorresponding conditions of engine instantaneous parameters such as mean effectivepressure, fuel consumption rate and fuel consumption for hundred kilometers andrelative fuel/air ratio, analyses the working characteristics under the actual road test.It can be concluded that the method developed in this paper could be applied forthe detection of performances under transient operating conditions of any vehicle,with reasonable accuracy. What’s more, the operation of the software is simple, theapplicable scope is wide, which can provide guidance for the design and developmentof the vehicle and powertrain, at the same time this method can improve the efficiencyof development and shorten the development period and saving the cost.