Study On Characteristics And Experimental Platform Of Hydro-pneumatic Suspension Systems Of Overall Vehicles

For unit energy storage ratio and nonlinear rigidity,the hydro-pneumatic suspension system has advantages over the traditional suspension.So it has been paid attention to by some vehicle engineering researchers.In order to design and manufacture a hydro-pneumatic suspension system with excellent performance,it is necessary to carry out relevant tests and research continuously.However,there are few experimental platforms for testing the characteristics of the vehicle's hydro-pneumatic suspension system at home and abroad,which seriously restricts the research on the coupling characteristics of the suspension system.To this end,this paper has carried out related research around the experimental platform of the hydro-pneumatic suspension system.The main contents are as follows:(1)A test platform based on the hydro-pneumatic suspension system of overall vehicle was developed and designed.It can used to simulate the roll motion of the vehicle during cornering,the pitching motion during braking or starting,and the bouncing motion when encountering uneven road surface,etc,and to Analyzing the vehicle coupling characteristics of the hydro-pneumatic suspension system under various working conditions.Researchers at home and abroad usually think that the axis of the suspension cylinder is installed perpendicular to the axis of the axle.This is not the case in practical applications.Therefore,a suspension cylinder mounting angle adjustment device was designed on the test bench in this paper.It can use to study the influence of the installation angle of the suspension cylinder on the performance of the suspension system.(2)The accumulator was tested under a variety of different conditions.The results show that when the accumulator was under normal working pressure,the elastic force of the bladder itself had little influence on the gas and liquid pressure in the accumulato,and the influence on the performance of the suspension system can be ignored.The gas polytropic exponent is usually regarded as a constant in theoretical and simulation analysis,however,it is found by experiments that,in a closed airbag,the volume compression ratio and volume compression rate of the accumulator gas had an influence on the gas polytropic exponent.Thus it affected the characteristics of the hydro-pneumatic suspension system.The gas polytropic exponent was corrected by analyzing the experimental data and studying the variation law of gas polytropic exponent with volume compression ratio and volume compression rate.And it was more in line with the actual situation,which provides a reference for relevant practical engineeringapplications.(3)The model of the hydro-pneumatic suspension system experimental platform of overall vehicles was established by using ADAMS and AMESim software.The simulation parameters of the accumulator and other components were parameterized according to the modified law of gas polytropic exponent change and design requirements,and the corresponding data were obtained by co-simulation of ADAMS and AMESim.Considering the change of the initial installation angle of the suspension cylinder,the calculation formulas of parameters characterizing the characteristics of the suspension system were derived,such as the calculation of the relevant force and torque when the vehicle was in the roll,pitch and vertical motion.(4)The experiment of the hydro-pneumatic suspension systems was carried out,and the experimental results was compared with the simulation.The better coincidence degree between the experimental and simulation data verified the rationality and credibility of the results,and the basic characteristics of the vehicle's hydro-pneumatic suspension system was got.When the roll and pitch rotation speed of the frame was zero(that is when the damping force in the suspension system is zero),the rolling static torque and pitching static torque of the hydro-pneumatic suspension system increased with the increasing installation angle of the suspension cylinder,and the range of the rolling static torque and pitching static torque of the hydro-pneumatic suspension system did the increasing frequency and amplitude of the sinusoidal excitation signal(that was the area enclosed by the torque curve increases).The characteristics of energy absorption and vibration reduction of the hydro-pneumatic suspension system were nonlinearly enhanced.It fully demonstrates the advantages of hydro-pneumatic suspension over traditional suspension.