Formation of the dynamic system of the test bench for transmissions at the design stage

Abstract

The problem of the discrepancy between the dynamic properties of the transmission on the test bench and the transmission of production vehicle was analyzed. When the loads of a dynamic na-ture are reproduced on the test bench, in a number of cases, after tests, there are obtained the results that do not correspond to the results of its operation. Usually the composition and scheme of the power flow transmission, as well as the elastic-inertial parameters of the elements of the mentioned transmissions, differ significantly. The test bench for transmissions usually does not include the chassis of vehicle, suspension and a number of other components and assemblies. The test bench is also usually driven by an electric machine rather than an internal combustion engine. During opera-tion the dynamic loading of the vehicle's transmission is influenced by the joint work of each of its units, which has a direct or indirect effect on the passage of the power flow through the transmis-sion. In the mode of variable loads of bench tests, this loading is influenced by the joint operation of the tested transmission with the transmission units of the test bench, which have different dynamic characteristics. The authors proposed the method, which allows at the design stage to form a set of dynamic parameters of the stand elements in such a way that the dynamic properties of the stand transmission correspond to the dynamic properties of the transmission of a production vehicle. There was offered a method for converging the dynamic loading of transmission on the test bench and as part of a production vehicle due to the purposeful formation at the design stage of the intrinsic frequency characteristics of the test bench transmission so that they correspond to the maximum extent to the characteristics of the vehicle transmission. The varying of the values of the inertial masses and elastic connections of the transmission elements of the test benches, the spectra of their natural frequencies are formed in such a way that in shaft line on modes, when the main part of fa-tigue damage accumulates, a picture of torsional vibrations is similar to those observed in the transmission of a production vehicle.