Kinematic Research On Several Typical Steering Mechanisms

The steering characteristics of automobile steering system have significant influence on the steering stability and driving safety. The steering characteristics of automobile, which is the key factor affecting the driving comfort and the working life of tire, are determined directly by the design of steering mechanism, therefore, the research of steering mechanism is of necessary and valuable.Three typical steering mechanisms, including integral type, rack and pinion pull-rod type and symmetric rod type, which classified according to the layout of steering linkage are chosen in this paper. Three plane mathematical models of the three steering mechanisms are established respectively, based on which the correlate equations of the left and right steering wheels'steering angle of the three steering mechanisms are deduced. The relation curves of the left and right steering wheels'steering angle are plot respectively by programming in assembler language C++Builder.The result that the left and right steering wheels'steering angle of the three steering mechanisms is symmetrical with respect to the lineβ= ?αis discovered, which is proved by mathematical technique respectively.The deviation of steering mechanisms is analyzed. The calculation formula of four kinds of deviation including deviation of right steering wheel's angle, deviation of steering centerⅠ, deviation of steering centerⅡand deviation of steering toe-in are deduced, and four kinds of deviation curves of the three steering mechanisms are plot in the program of C++Builder. The impact that mechanism parameters of the three steering mechanisms have on the deviation is analyzed by the method of orthogonal design, therefore, the mechanism parameters that have the greatest effect on the steering mechanism are obtained.The actual steering angle and actual turning radius are defined. Combined with the steering toe-in angle, the calculation formula of actual steering angle and actual turning radius are deduced under the occasion that there is pre-toe-in or not.According to the Ackermann steering principle, four kinds of optimization objective functions of the integral steering mechanism are established based on the angular deviation of outside steering tire, steering center deviationⅠ,Ⅱ, steering toe-in deviation. The result of optimization is analyzed and the optimized effects under the four kinds of objective functions are compared.