| NVH(Noise,Vibration,Harshness)performance is one of the key performances of pure electric vehicles.As a key component of electric vehicle power output and transmission,the NVH performance of electric drive assembly directly affects the performance level of the entire vehicle.Spline is a key component connecting drive motor and reducer,and its connection characteristics are affected by spline centering method and assembly errors.For this reason,this paper has studied the spline connection characteristics and their impact on the dynamic response of new energy reducers,and mainly completed the following work:(1)The theoretical stiffness of each tooth of the spline is analytically calculated using the trapezoidal method,and the theoretical stiffness of each tooth under the radial misalignment of the spline pair is calculated.The finite element method was used to study the spline connection characteristics and compared with the theoretical calculation results.When the spline pair has radial misalignment,one part of the key teeth of the spline pair is in a tight fit,and the other part is in a loose fit;When there is angular misalignment,the contact position of the tooth surface changes,and an overturning moment is generated under the action of the load on the spline tooth surface.This overturning moment will cause the spline pair to shift towards the center direction,reflecting the self-alignment of the spline pair.Both types of misalignment can cause changes in the load on the spline teeth,further affecting the stiffness of the spline pair.(2)A dynamic model of the reducer considering the connection characteristics of the spline pair is established,and the time-varying meshing stiffness of each gear pair of the reducer is calculated using the potential energy method.The meshing damping,mass and inertia of each component,connection stiffness and damping of the shafting,support stiffness and damping of the bearing,and other related parameters in the model are calculated using numerical methods.Then,the system model is solved using the Runge-Kutta method to obtain the dynamic meshing force of the gear pair under the corresponding working conditions.This dynamic meshing force is the loading excitation force for subsequent finite element analysis.(3)A finite element model for the vibration of the reducer housing is established,and the dynamic meshing force derived from the reducer dynamics model is loaded onto the finite element model as an excitation.The vibration response of the corresponding measurement points on the surface of the reducer housing is analyzed and obtained.A test rig for the reducer was built and corresponding vibration tests were completed.The vibration responses of the measured points on the surface of the reducer housing under the same working conditions were picked up.By comparing simulation and test data,it was found that the consistency was good,demonstrating the effectiveness of the dynamic model and the finite element model.(4)Based on the validated system dynamics model,the influence of the centering method and misalignment of the spline pair on the dynamic response of the system is analyzed.The results show that when the spline pair is centered with a large diameter,the peak value of the dynamic transmission error increases with the increase of the radial misalignment;With the increase of angular misalignment,the peak value of dynamic transfer error first increases and then decreases;When the spline pair is keyside centered,the peak value of the dynamic transmission error first increases and then decreases as the radial misalignment increases;The peak value of dynamic transfer error increases with the increase of angular misalignment,but the amplitude of change is not significant;When the spline pair is small diameter centered,the peak value of dynamic transmission error increases with the increase of radial misalignment;As the angular misalignment increases,the peak value of dynamic transfer error first increases and then decreases. |
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