Study On Non-circular Sector Teeth Profile Of Variable Ratio Steering Gear

With the rapid development of economy and the popularity of cars, more and more requirements for the steering performance of the car in the process of driving are gotten. As important parts of automobile steering system, the transmission performance of bit quality has great influence on the performance of the steering system. Two types of transmission ratio models commonly used in automotive industry. One is the ladder form transmission ratio model, which leads to discomfort during driving, the other is the smooth transition curve transmission ratio model, which is complicated in calculation. Therefore it is necessary to study a variable ratio of the non-circular sector which is stable and easy in process.Aimed at the problems of the two kinds of transmission ratio models, a method for the design of rack and pinion steering gear is presented based on the constant ratio curve of constant drive ratio steering gear. And then, in order to provide basis for the follow-up analysis of the meshing performance of the rack and pinion, some parameters of non-circular gear fan rack drive are discussed, such as instantaneous center curve, coincidence degree, sliding coefficient, master-slave wheel and acceleration.According to the plane engagement equation and the coordinate transformation formula, the parametric equation of non-circular gear is established. According to the envelope principle and the rack generating method, the modeling of gear rack is realized in MATLAB. And some of the meshing performance of the model is analyzed. Finally, the 3D model is realized in SolidWorks.On one hand, the 3D model is analyzed in ANSYS Workbench to prove that the designed rack meets the strength requirement. On the other hand, the 3D model is analyzed in ADAMS to obtain the rack velocity and acceleration curve. And the results are consistent with theoretical calculation. Therefore, it can be proved that the characteristics of stable transmission is obtained by the designed gear rack.At last, the machining program of machining this kind of non-circular sector is developed on the general platform of HNC-8. Then, this kind of gear is machined and verified in HUBEI TRI-RING MOTOR STEERING GEAR CO.LTD.