Research And Design For Automotive Differential Load Sharing Device

Differential is an important part of automotive transmission system, which used to implement each wheel rotating at different speed to meet the need of the vehicle kinematics. Currently, the most widely used differential is symmetrical cone planetary gear differential. Differential located at the end of the transmission chain, it operates at a relatively high torque and transmits substantial power. However, the bearing capacity of the structure is limited by the uneven planetary gear load distribution which caused by manufacture errors, installation errors, etc. The load sharing device can make the load distribution more uniform, then, improve the bearing capacity and the reliability of the differential. What’s more, it could reduce the vibration and noise too.A coupling dynamics model of translation torsion of symmetric cone planetary gear differential is constructed by the method of lumped parameter modeling. The process of dynamics model construction considers the nonlinear element of transmission system. The nonlinear element includes time-varying mesh stiffness, meshing error, damping and bearing support stiffness and so on. According to the elastic deformation condition of meshing bevel gear, the differential equation of the differential transmission system was established.The load characteristics of differential in straight driving and turning state from the static and dynamics were analyzed. In this paper, the statics load sharing characteristics and dynamics sharing characteristics were studied firstly. The influence was studied of manufacture errors, assembly error, input power, the number of planet gear, bearing support stiffness, time-varying mesh stiffness to load sharing coefficient of sub-system. And some valuable conclusion were obtained, such as improve the accuracy of the planetary gear, reasonable layout the phases of errors and reduce the radial support stiffness is more effective to improve the system load average performance, more the number of planetary gear, the non-uniform load phenomenon more serious.The working principle and technical characteristics of the existing load balancing device were analyzed. A flexible shaft planetary loading device was presented for the differential planetary system, which based on reducing the planetary wheel radial support stiffness. In this paper, the method of structure design of the device was introduced in detail, compliance of the device and load effect was demonstrated by theoretical analysis and finite element calculation. At last, experiment was carried out and the result shows that the device can effectively improve the load distribution of the planetary gear differential.