Modeling And Performance Analysis Of Anti-roll And Anti-pitch Hydraulically Interconnected Suspension For Ambulance

With the development of Chinese medical level,the ambulance industry has a broad market.However,the technology of the traditional chassis suspension system is backward and cannot meet the performance requirements of the ambulance.In the common driving conditions of ambulances,the roll of the car body during high-speed cornering seriously affects safety,the pitch of the car body during emergency braking affects the comfort of the occupant,and the large longitudinal load transfer rate affects the front and rear braking force distribution,reducing the braking efficiency.Vertical vibration of the car body caused by uneven road surface aggravates the patient's body pain and psychological stress,even causing "secondary damage".In addition,excessive car body vibration can cause damage to medical rescue equipment in the ambulance.Therefore,the solution to fundamentally improve vehicle handling and ride comfort is to develop a new suspension system that is more suitable for ambulances.This thesis takes ambulance as the research object,in order to improve the anti-roll and anti-pitch performance of the vehicle,and to ensure ride comfort.Hydraulically interconnected suspension has the advantage of decoupling vehicle motion modes and nonlinear characteristics,proposing a new anti-roll and anti-pitch hydraulically interconnect suspension system,and established a simulation model to study the performance characteristics of the suspension.Firstly,according to the working principle of the hydraulically interconnected suspension,designing suitable hydraulic component parameters.Obtain optimal parameters by using optimized design methods,the vehicle stability and ride comfort simulation test shows that the parameters meet the requirements of the objective function.Secondly,establishing a vehicle dynamics model with seven degrees of freedom mechanical and hydraulic coupling.The fishhook manoeuvre used to evaluate the extreme rollover capability of the car shows that the hydraulically interconnect suspension can greatly improve the anti-roll performance of the vehicle compared to the anti-roll bar.The emergency brake and double shift line combined condition shows that the hydraulically interconnect suspension not only keeps the lateral stability of the vehicle far better than the anti-roll bar,but also overcomes the weakness of the anti-roll bar in anti-pitch,and significantly improves the longitudinal stability of the vehicle.Finally,specificity of transporting patients for ambulances,this thesis expound the necessity of establishing vibration model of lying posture to evaluate the ambulance ride comfort.Random road test and pulse excitation test prove that hydraulically interconnect suspension improves vehicle ride comfort compared to traditional suspension.Proposing a feasible solution to solve the conflict between vehicle stability and ride comfort.