Analysis And Research On Rotational Clearance Characteristics Of Automobile Constant Velocity Universal Joint Drive Shaft Assembly

Constant velocity joint (CVJ) drive shaft is an important component of modern automobile transmission, which is widely used in front-wheel drive and four-wheel-drive car. It affects steering-drive performances, operation stability and comfort of the car directly.However, due to lubrication requirements, spherical sub-assembly requirements, manufacture and other reasons, clearance does exit among the parts of CVJ drive shaft inevitably. The rotational clearance and the resulting axial clearance can generate vibration and noise during driving, and also affect the performance and life of the CVJ seriously. So it’s necessary to research on the changing law of rotational clearance and characteristics about CVJ drive shaft.Firstly, the motion trace equations of steel-ball at any swing angle was deduced based on the transformation principle of spatial coordinate system and motion model of Rzeppa CVJ, furthermore, the rotational model of Rzeppa CVJ was obtained based on the principles of geometry, and the changing law of Rzeppa CVJ at any swing angle and rotating angle was analyzed by using the graphical visual function of Matlab.Secondly, the rotational clearance model of CVJ drive shaft was deduced combined with the one of Tripod’s. After sensitivity analysis about the structural parameters, the sequence of priority level and co-relationship of each structural parameters was obtained. The optimum fitting position of CVJ drift shaft was got through the optimization of the assembly parameter, and manufacture requirements on related parts were proposed based on the weakest rotational clearance fluctuations of CVJ draft shaft.Thirdly, four-ball-pin CVJ was proposed in the sliding end, and a new structure, optimized channel Rzeppa CVJ, was proposed in the fixed end, and the rotational clearance comparison between the new structure and the traditional ones was analyzed.Fourthly, the multi-body dynamics model with clearances of drive shaft was established in Adams, and the rotational clearance tests were done in this virtual prototype. The reasons about the error between theoretical and simulation results were analyzed. In addition, rotary vibration tests were done base the model. The test results were also analyzed.At last, by using the test bench developed by SJTU, the clearances of the fixed end, the sliding end and the CVJ drive shaft were measured, moreover, the test results, simulation values and theoretical values were compared together, the errors between these results were also analyzed.The results show that the rotational clearance model of CVJ drive shaft is a function of12variables, including structural parameters, operating parameters and the relative assembly position. The fluctuations of rotational clearances lead to the rotational vibration of CVJ drive shaft, Under the same size specification and machining accuracy, the application of new structural CVJ or optimized assemble CVJ drive shaft can weaken the fluctuation of rotational clearances and vibrations of drive-shaft to some extent. These results provide a theoretical basis for CVJ drive-shaft design, and also some reference value on guiding the assembly process, the application of new structural CVJ and the development of test bench.