| Electric steering gear is an actuator that converts computer control signals into rudder blade deflection.It is widely used in various aircraft due to its high accuracy,fast response speed,and high power density.With the continuous development of aircraft in the direction of high speed and high maneuverability,higher requirements are placed on the performance of electric steering gear.The rotor system is a key component of the electric steering gear,and its dynamic characteristics directly affect the stability and reliability of the entire steering gear system.Rotor dynamics are closely related to its supporting characteristics.With the continuous increase of speed,the supporting dynamic stiffness of rolling bearings changes significantly compared with the static stiffness,and when the rotor system needs to run to ultra-high-speed working conditions,traditional rolling bearings cannot meet engineering requirements.As required,magnetic bearings came into being and are widely used.Therefore,it is very necessary and urgent to study the dynamic characteristics of the electric steering gear rotor system under variable support conditions.This paper combines the performance characteristics of the rotor system under various supporting conditions,and carries out the research on the dynamic characteristics of the electric steering gear rotor system from different angles and analysis methods,which has important scientific research value and engineering significance.According to the structural characteristics of the electric steering gear rotor system supported by the static stiffness of the rolling bearing,this paper modifies the mainstream dynamic analysis method—Riccati transfer matrix method,and then combines the requirements of the lightweight and low vibration of the rotor system in the design process,based on the orthogonal test Design and ISIGHT integrated optimization platform,use response surface function method to construct the multi-objective optimization approximate model of the electric steering gear rotor system,select NSGA-II multi-objective genetic algorithm to solve the optimization,the quality of the rotor system after optimization is reduced by 4.8%,The first-order natural frequency increased by11.0%,and the corresponding amplitude decreased by 11.3%.In order to obtain the nonlinear stiffness of the rolling bearing under different radial loads and verify the correctness of the value of the static stiffness of the bearing,the stiffness test experiment of the rotor rolling bearing was designed.The experimental results show that the maximum error between the static stiffness of the bearing and the measured data is only 5.3%.On this basis,the natural frequency test of the initial rotor system of the electric steering gear was carried out through the force hammer experiment,and the test results were not much different from the results of the numerical analysis,which indicated that the modification of Riccati transfer matrix method was reasonable and correct,and it also showed the credibility of the multi-objective optimization results from the side.With the increase of the rotor speed,the supporting rigidity of the rolling bearing will change obviously due to the effect of centrifugal force.Based on the Hertz theory and the outer ring raceway control theory,the force method is applied to analyze the bearing stiffness characteristics of the rolling bearing under the influence of high-speed effects,and then the dynamic characteristics of the rotor system under the influence of the static and dynamic stiffness of the support are solved separately according to the modified Riccati transfer matrix method.The numerical solution results of the system model of the rated speed corresponding to the dynamic stiffness of the support are compared and verified with the finite element analysis results.The supporting characteristics of magnetic bearings not only depend on the structural characteristics of the bearing,but also closely related to its control system.When the rotor system of the electric steering gear is operating at ultra-high speed,the pole moment of inertia and diameter moment of inertia of the disc cannot be ignored,and then the rotational moment of the electromagnetic shaft section is taken into account to further improve the Riccati transfer matrix method,and apply this method to solve and analyze various parameter variables The influence law on the critical speed and unbalanced response of the magnetic bearing rotor system. |
PDF Full Text Request