Theory Design Simulation And Test Of Hydro-pneumatic Torsion-free Suspension

When the off-road vehicle runs in the accidented road, there are two import points: one is the performance of handling stability and vehicle pass-ability, but the wheel ability of adhesion to the ground is the key factor of effecting on the performance of handling stability and vehicle pass-ability. And the wheel ability of adhesion to the ground has something to do with not only the structure of tire but also the suspension system structure. That is the distribution of vertical load of tire and the using of the adhesion force are determined by the suspension structure. So the purpose this thesis is how to design the new style Hydro-pneumatic torsion-free Suspension to realize the good adhesion to the accidented road. And the other is the life of body. Accidented road will result in the evident difference of the vertical load for four wheels; therefore a torsion will be appeared in body. Furthermore it will strike the body. The torsion and strike will deform or destroy the body, so the significance of design a new style Hydro-pneumatic torsion-free Suspension means eliminating the redundant torsion in body.Based on the problem and the torsion-free principle of whole couple Hydro-pneumatic suspension system revealed by Prof. Konghui Guo and combined with the subproject of National Natural Science Foundation of China—"Study on whole-coupling hydro-pneumatic suspension system". This thesis isabout the study on the effect of torsion-free Suspension in eliminating the redundant constraint, reducing the torsion load and the strike stress, improving the distribution of load of tire and the ability of adhesion to the ground.This thesis introduces the principle, classification, character and study development about hydro-pneumatic spring and torsion-free Suspension. And hydro-pneumatic spring has been used in engineering vehicle, military vehicle and luxury car. There are lots of studies about it, but this study on torsion-free Suspension with hydro-pneumatic spring is in the initial stage for the first time.This thesis analyses the work principle of the single nitrogen chamber and hydro-pneumatic separate spring which is suitable to torsion-free Suspension. Based on the structure principle of hydro-pneumatic spring, I have built the virtual model of hydro-pneumatic spring with ADAMS/Hydraulics and analyzed the math model of hydraulic oil, single action cylinder, gas accumulator, orifices and check valve. And then I have analyzed the spring and damp character and the matching principle of hydro-pneumatic spring, simulated the displacement and velocity character of this model with different frequency and swing power, revealed the rule of the spring and damp character influenced by the structure parameter of hydro-pneumatic spring and provided the rule for choice or design of hydro-pneumatic spring.The innovation of this thesis deducts the relationship of the four vertical restrictions by the accidented and the average vertical input, average rolling input, average pitching input and torsion input. then illustrates the action principle of the hydro-pneumatic torsion-free Suspension and makes a standard formula that estimates the torsion torque and design rule for torsion-free cylinder. I have built the couple machine and hydraulic model of the hydro-pneumatic torsion-free Suspension in ADAMS/View, including body model in CATIA, hydro-pneumatic spring model, torsion-free cylinder model and power test-rig model. Based on these models, I have done test-rig experiments, designed different roads to test the effect of torsion-free system including single frequency road power, step road power and random road power, measure the pressure and the displacement of thefour hydro-pneumatic springs, body acceleration response and the displacement of the torsion-free cylinder. After data processed, analyzed the simulation and test data which stand for torsion in body including pressure difference, the ability of adhesion to the ground and acceleration response by comparing the torsion and torsion-free situation to prove that the model is right and the torsion-free system is effective.The results of simulation and test improve that: added the torsion-free system, the effect of the ability of adhesion to the ground and decreasing the torsion in body is evident, but the vibration character of body is not bad, the anticipative object is good for the next work including real car simulation and test.