Simulation And Test Research Of Hydro-pneumatic ISD Suspension

Inerter has good vibration isolation performance in low frequency vibration,ISD suspension composed of inerter,spring and damper can improve vehicle ride comfort,which has high engineering application value.Especially the two-stage series ISD structure has a prominent vibration damping performance,which has wide application prospect,but the suspension has an engineering problem about space layout.According to characteristics of a new fluid inerter and hydro-pneumatic spring,taking integration design as a method,this paper puts forward a kind of hydro-pneumatic ISD suspension.Through modeling,simulation and experiment,the paper analyzes the vibration reduction performance of hydro-pneumatic ISD suspension and the feasibility of the layout of the prototype,the simulation and experimental results show that the hydro-pneumatic ISD suspension can improve the low frequency response characteristics of the vehicle,not only reduce the vibration of the car body and improve the ride comfort,but also reduce the wheel beat and improve the grounding of the tire,which has laid the foundation for the engineering of ISD suspension.First of all,this paper introduces the mechanical and electrical network strict corresponding relation based on the concept of inerter,analyzing the important elements of hydro-pneumatic ISD suspension,fluid inerter,and discussing the anti-resonance theory and the damping mechanism of two-stage series ISD suspension.Secondly,according to the “mechanical-hydraulic” similarity relation,this paper demonstrates the equivalence relation of hydro-pneumatic ISD suspension and two-stage series ISD suspension,establishing the mathematical model of hydro-pneumatic ISD suspension and the physical model based on AMESim,and analyzing its working principle and movement characteristics.Thirdly,this paper establishes the 1/4 system dynamics model and uses multi-objective genetic algorithm to optimize the structure parameters.The simulation results show that hydro-pneumatic ISD suspension can improve the low frequency response characteristics,restrain the resonance of the vehicle body,and ensure the reliability of the movement of the vehicle,improve vehicle ride comfort and handling stability.This paper establishes the whole seven-degree freedom vehicle model of hydro-pneumatic ISD suspension,solved the problem ofthe AMESim can only achieve one dimensional simulation of hydro-pneumatic ISD suspension.The whole vehicle simulation results show that under random excitation,the center of mass of hydro-pneumatic ISD suspension vertical acceleration,pitch and roll of body acceleration decrease obviously,vehicle ride comfort performance improved;Under impulse excitation,the hydro-pneumatic ISD suspension can reduce the response peak-to-peak value,reducing body oscillation.Finally,the hydro-pneumatic ISD suspension is built,which is installed on the test vehicle frame,the paper used the tire coupled road simulator to realize the road spectrum input,carried out the nature frequency test,pulse excitation test,random excitation test,frequency response characteristic test and distorted road test.These tests prove the vibration isolation performance of hydro-pneumatic ISD suspension and engineering solutions.The nature frequency test shows that compared with the traditional hydro-pneumatic suspension,the ride frequencies of the left front body and right rear body on hydro-pneumatic ISD suspension are reduced by 12.18% and16.35%,respectively,and the acceleration of the ride frequencies decrease by 27.97% and42.36%,respectively;The random excitation test shows that when the speed is 30km/h,center vertical acceleration,left front car body vertical acceleration,left rear car body vertical acceleration,angular velocity of pitch and roll rate were decreased by 11.41%,9.93%,12.43%,2.14%,1.51%,respectively.It can be concluded that hydro-pneumatic ISD can significantly inhibit the vibration of body vertical,pitch and roll direction,improving the vehicle ride comfort.Left front axle vertical acceleration and left rear axle vertical acceleration can be reduced by3.01% and 3.60%,respectively,which shows that hydro-pneumatic ISD suspension can effectively reduce the dynamic load and improve the safety of the vehicle;In the test of frequency response characteristics,the hydro-pneumatic ISD suspension body resonance is effectively restrained,and the ride comfort of the vehicle is improved.At the same time,the high frequency resonance caused by the sprung mass is also slightly improved,tire grounding performance improved.In the test of distorted road,the body pitch angle and side angle are reduced,which can reflect the hydro-pneumatic ISD suspension can maintain the body posture stability,suspension dynamic travel control within a reasonable range.Compared with the two-state series ISD suspension,the hydro-pneumatic ISD suspension structure is compact,easy to arrange the vehicle,and the engineering implementation is strong,which lays the technical foundation for the industrialization of the ISD suspension in the future.