EFFECT OF STEERING COLUMN TILT ANGLE CHANGE ON STEERING RATIO AND ITS OPTIMIZATION METHOD

摘要

Research and/or Engineering Questions/Objective Recently, most of steering system usestiltable column and universal joint. Because of the universal joint, steering system has torque variation. Torque variation is usually set symmetrically with steering center point of tilt up and down. However when steering column is tilted according to driver's position, steering system goes to asymmetric situation. Because of this asymmetry, steering has different steering feel and agility in turning right and left hand side. In this paper, it is explained a method for maintaining the steering symmetry according to column tilt. Methodology First, express the steering system motion is expressed by formula and set some parameters according to vehicle specifications. Then torque variation asymmetric characters are considered according to universal joint phase angle and column tilt angle. By analyzing these characters, it could be found phase angle which makes minimum torque variation asymmetry when column tilt angle changed. Results Optimized universal joint phase angle was found using proposed method. It was proved that using the optimized phase angle, torque variation asymmetry was decreased compare with reference value. The steering model with optimized phase angle was applied to a vehicle simulation model. By analyzing the vehicle model, it has shown that the vehicle has symmetric steering character in agility. Limitations of This Study The proposed method doesn't include the effect of manufacturing tolerance. The optimized phase angle has very narrow range. However universal joint phase angle has tolerance, so universal joint phase angle might be out of optimized value. What does the paper offer that is new in the field including in comparison to other work by the authors? The result and method about optimized steering system in this paper increase symmetric in steering system for most of vehicles. Conclusions New method for setting steering system about maintain steering symmetry in column tilting have been developed. This method can be applied most for vehicles. steering system for most of vehicles. Conclusions New method for setting steering system about maintain steering symmetry in column tilting have been developed. This method can be applied most for vehicles.