| Air suspension is widely used in commercial vehicles due to its excellent vibration isolation performance and height adjustability characteristics.Nowadays,three-axle commercial vehicles mostly adopt trailing arm air suspension.In order to reduce the problem of uneven tire load distribution caused by the phenomenon of statically indeterminate,interconnected air springs are used in the middle and rear axles to solve the problem of uneven load of the two axles under static load.However,due to various restrictions on the gas flow rate,the normal loads of these two axles under impact are quite different,which greatly restricts the performance of the tires and affects the steering stability and safety of the vehicle.Therefore,in order to solve the problem of uneven load distribution of three-axle vehicles under large impact conditions,this thesis proposes an elastic double-interconnected walking-beam type air suspension,and the analytical model of the vehicle equipped with this novel air suspension is established.Vibration characteristics of the novel air suspension and the influence of the structural parameters of balance mechanism on ride comfort are studied.The major contents of this thesis are as follows:(1)The static and dynamic stiffness experiments of the air spring are carried out.Then,combining the Berg friction model and the least square method,a method for identifying the effective area of the air spring and the parameters of the friction model was proposed.Based on the principle of thermodynamics and the Berg friction model,a nonlinear mechanical model of the air spring is established.The air spring forces with different excitation amplitude and frequency are calculated and compared with the test results to verify the correctness of the air spring model.(2)The structure and working principle of the elastic double-interconnected walking-beam type air suspension are introduced.Based on the air spring model obtained previously,an interconnected air spring model is further established.Based on the multi-body dynamics theory,the dynamic equations of the mechanical system of the vehicle with the novel air suspension are derived.The vehicle equipped with conventional air suspension is also modeled for the purpose of the comparison.A vehicle model with two different suspensions was established in the ADAMS-Simulink environment.Taking the speed bump road as input,the sprung mass accelerations of the two vehicles equipped with different suspensions are calculated by the analytical model and the ADAMS model,and the calculation results of the two models are compared to verify the correctness of the analytical model.(3)The calculation method of ride comfort index and load of suspension components under the analytical model are introduced and explained.Taking the roadblock pathment and random road as the input of the analytical model,respectively,the sprung mass acceleration,tire normal force,suspension stroke and suspension component load of the vehicles equipped with novel air suspension and the conventional air suspension are calculated and compared.The results show that the novel air suspension proposed in this paper can achieve better tire load distribution,thereby improving the driving safety of the vehicle and reducing the damage to the road surface.At the same time,the suspension load peak is lower,reducing the probability of suspension damage.Finally,the influences of the structural parameters of the equilibrium mechanism in the novel air suspension as well as hose parameters of the interconnected air spring on ride comfort are studied. |
