Research On Air Spring Vibration Isolator With High Air Tightness

The air spring has low rigidity and high load bearing,and has obvious advantages in vibration isolation of high-end equipment in the fields of precision manufacturing and measurement,aerospace and navigation.However,air springs generally require high-pressure gas to be sealed in the load-bearing cavity by means of rubber or piston structures.Due to the microscopic pores of the rubber material,gas leakage is inevitable,which brings great stability to the posture of the vibration isolation equipment in long-term service challenge.How to greatly improve the air tightness under the premise of ensuring high vibration isolation performance has become the bottleneck of the development of air spring vibration isolation technology.This thesis abandoned the traditional thinking of rubber membrane directly sealing gas,innovatively proposed a multi-layer-multi-medium combination sealing idea of "rubber membrane-viscous fluid-high pressure gas",and then analyzed and designed the prototype of a new high-tightness air spring vibration isolator And carried out relevant verification tests.The main work and innovation of the thesis are as follows:First,for the low stiffness and high air tightness requirements of air springs,according to Darcy’s law,the leakage mechanism of different fluids in the micropore structure of the air spring rubber membrane was analyzed,and the fluid viscosity is the most important factor affecting the leakage rate.A new idea of multi-layer-multi-media combination sealing of "rubber membrane-viscous fluid-high-pressure gas" was put forward,and the overall scheme of high-tightness air spring was clarified.Secondly,considering the influence of compressed gas and rubber membrane structure on the rigidity of the air spring,an analysis model of the rigidity and stress of the air spring was established.The key dimensions and hardness of the rubber membrane,the size of the bearing area and the edge fillet were analyzed.The influence of stiffness and rubber membrane stress distribution.Combined with the feasibility of the manufacturing process,the effectiveness of a compact horizontal vibration isolation rubber ring with axial waist holes to reduce radial stiffness was analyzed.The detailed design of the bearing and sealing structure of high air tightness air spring was further completed,and the prototype of high air tightness air spring vibration isolator was developed.Finally,the static stiffness test of the prototype of the air spring isolator developed was completed,and the results showed that the error between the theoretical and actual measurements was only 3.86%.Aiming at the problem that the relative error is relatively large when testing low-leakage air springs by conventional air pressure measurement methods,a high air-tightness direct detection method for measuring the gas leakage amount under water immersion was proposed,and the test schemes for the gas leakage characteristics of the sealed gas nozzle and the rubber membrane were designed respectively.The gas leak test for the sealed gas nozzle lasted for 10 days.The results showed that the gas valve leakage rate expressed by gas pressure drop was only 0.006% / day on average,and the leakage rate gradually decreased with time.The long-term bearing height stability test of the air spring was further completed.The results showed that the bearing height decreased by about 0.115 mm within 40 days under the combined action of gas leakage and rubber membrane creep,indicating that the overall leakage rate of the air spring did not exceed 0.068% / day.This thesis comprehensively considered the influence of the rubber membrane on the stiffness,bearing and air tightness of the air spring,and proposed a high air tightness air spring design method and a high air tightness precision test method.The results proved that the air tightness has been significantly improved.