Research Of The Bench System Resistance Test Method Based On The Chassis Dynamometer

As an important indoor bench testing equipment, automotive chassisdynamometer can not only test the dynamics of car, but also can measure theemissions targets and fuel consumption of multiple loading conditions. However,the accuracy and reliability of all test results depend on whether the chassisdynamometer can make a realistic simulation of the car’s road resistance.With the improvement of the national requirements on pollution coming fromvehicles, different types of vehicle fuel consumption limit standards arelaunched in automotive industry. With the development of new technologies,there is a new detection method called carbon balance method, which can beregarded as an alternative to the traditional fuel consumption detectionmethods, has been developed, and enters the trail phrase. The correspondingstandards have been promulgated and this method will be utilized widely.Emissions detection already used the emission test working is popularized;Power performance test bench test has been in operation for many years. Inorder to ensure the accuracy of the test results of this method, the chassisdynamometer must simulate the road driving conditions more realistic. Therealization of actual simulation of the road driving conditions realisticallydepends entirely on the dynamometer’s load simulation and system resistance.But in general, we only consider air resistance, climbing resistance, rollingresistance of driven pulley as well as some of the acceleration resistanceand ignore the resistance of the bench system. Then the chassis dynamometercan not make a realistic simulation of the automotive road resistance andproduces errors when test automobile dynamic performance and fuel consumption.In particular, carbon balance method need an accurate load when detect fuelconsumption and system resistance is an important part that can not be ignored.The bench system resistance mainly includes two parts. One is the rollingresistance of the bench, which is also called tire rolling resistance---the hysteresis loss due to elastic deformation of the tire when the vehicle istesting on a chassis dynamometer. The other is the internal resistance of thebench, which is the resistance due to friction when the chassis dynamometeroperates. When the vehicle is running on the chassis dynamometer, bench systemresistance is a dynamic value, not a definite value. This dissertation isprimarily for the research of the generation and test method of the systemresistance.1、On the basis of analysis of the automotive road resistance and the testloading force of the chassis dynamometer, this article establishes amechanical model when the vehicle run on a chassis dynamometer at a constantspeed, and provide a theoretical basis for the next step of the paper.2、Combined with the analysis of the composition and shaping factors ofsystem resistance when the vehicle is running on a chassis dynamometer, thearticle studies the test method of each part of the bench system resistance.And the changing law is obtained through experimental verification andanalysis by the designed testing device.3、In view of the relationship between the bench system resistance andthe bench rolling resistance, the internal resistance, the article tests andstudies the bench system resistance by the reverse dragging testing method.The reverse dragging testing device is designed with the SolidWorks softwarethrough the analysis of the mechanical model of the reverse dragging testing.Finally, through the real vehicle experiment, the relationship between thebench system resistance and the speed of vehicle, axle weight is obtained,and the experimental data is fitted by Matlab software, the fitting curve isobtained. And this provide the bench system resistance in the real simulationof automotive road conditions when the automotive chassis dynamometer istesting fuel economy, dynamic performance and emission performance.