Research On Structural Optimization Of Front Suspension Of Electric Vehicle

With the growth of world population and the limitation of oil and other resources,the research of hybrid electric vehicle,especially electric vehicle,has become an important trend of current development,and the traditional fuel vehicle have a great influence on the environment,the research of electric vehicle will become the main trend of future development.The design of electric vehicle mainly adopts the method of converting the traditional fuel car into electric vehicle,which leads to the increase of the total body mass of the modified electric vehicle and have a great impact on the centroid position of the car.Direct modification of suspension of traditional fuel vehicle to electric vehicle can save time and cost,but due to the change of spring load quality,the basic adjustment parameters of front wheel will have a great impact,for example,the change of kingpin inclination angle,caster angle,scrub radius,toe angle,camber angle.The changes of these positional parameters will affect the driving stability of the vehicle.Therefore,it is necessary to optimize and analyze the suspension structure for driving comfort,obtaining the positional parameters that can match electric vehicle,to improve the driving stability of automobiles.Based on the problem of driving stability of a vehicle after modification,firstly based on its original parameters,static deflection and coil spring parameters suitable for electric vehicle front suspension are calculated.Then the two-degree-of-freedom mathematical model of vehicle vibration is established,Simulink is used to model and simulate,and the damping coefficient of the designed shock absorber is obtained.According to the wheelbase,wheelbase and minimum ground clearance of the original parameters,the coordinates of hard points corresponding to upper and lower arms,steering knuckles and hub of the suspension are calculated on the longitudinal plane,transverse plane and horizontal plane.Based on the above parameters,a three-dimensional model of double wishbone front suspension is established.After setting the suspension parameters,the first parallel wheel travel is carried out on the three-dimensional model of the suspension by ADAMS.The curves of basic adjustment parameters of front wheel,such as kingpin inclination angle,caster angle,scrub radius,toe angle and camber angle,with wheel travel displacement are obtained,the values of kingpin inclination angle,toe angle and camber angle are not in the reasonable range.Therefore,it is necessary to optimize the above positional parameters to make them enter the reasonable range.Through sensitivity analysis method,the influence rate of each hard point coordinate on positional parameters is obtained.Taking the range of hard point coordinates as the restraint condition,the above positional parameters are optimized by adjusting the coordinates of three hard points: the outer point of the upper arm,the outer point of the steering tie rod and the outer point of the lower arm.If the positional parameter is larger than the maximum value of the target value,it is necessary to adjust the hard point coordinates corresponding to the positive impact rate to reduce the impact rate,and finally reduce the value of the positional parameter to a reasonable range.If the positional parameter is less than the minimum value of the target value,it is necessary to adjust the hard point coordinates corresponding to the negative impact rate to increase its impact rate,and finally increase the value of the positional parameter to a reasonable range.The optimized three-dimensional model of front suspension is obtained by changing the hard point coordinates,it is concluded that the value of the kingpin inclination angle is still beyond the reasonable range after the parallel wheel travel.By introducing the boundary improvement method and combining it with sensitivity analysis method,the hard point coordinates are optimized again,and the parallel wheel travel is carried out on the three-dimensional model of the re-optimized front suspension.The kingpin inclination angle is within the reasonable range of the target model.Finally,the rationality of the suspension design and the correctness of the optimization method are verified by vehicle simulation test.