| Shock absorber plays an important role in the vehicle suspension system. As a car chassis main damping elements, it not only affects vehicle's comfort, also relates to the vehicle's handling and safety. Pneumatic shock absorber is a new type of shock absorber from 1960s, filled with high pressure gas, a certain back pressure is established in the oil barrel, which can significantly improve the shock absorber of the distortion threshold speed. Pneumatic shock absorber can eliminate the external characteristic distortion effectively, and improve the performance of shock absorber significantly, so it is widely used in the car. External characteristic is an important performance of pneumatic shock absorber, plays an important role in the development and use. External characteristic can come true through performance test. Researching the performance test of pneumatic shock absorber, accurately grasping the characteristics of pneumatic shock absorber, have important significance of improving the shock absorber and ride comfort of vehicle suspension.Based on introducing structure and working principle of pneumatic shock absorber, the testing standards of shock absorber are researched, and shock absorber test system based on virtual instrument is developed. Through researching evaluation of shock absorber performance, 6 performance tests are designed. Through testing pneumatic shock absorber both in the pneumatic state and in the non-pneumatic state, and comparing of the two test results, working characteristics of pneumatic shock absorber is analyzed. Specific content and conclusions can be summarized as follows:1 Based on the investigation of relevant references at home and abroad, the shock absorber status of test methods and test equipment are analyzed. There are power-showing characteristics test, speed test, life test, friction force test, aeration test, anti-foam test and sealing test in test methods for shock absorber. There are 3 types of mechanical, electrical, servo, and analyzing its advantages and disadvantages, can provide an important basis for development of shock absorber test system.2 Based on the introduction of shock absorber function and type, shock absorber of the structure and working principle is researched, the structures and working principles of the monocular, binoculars, and balloon-type pneumatic shock absorber are analyzed, the process and effect of high-pressure gas are paid more attention. The performance evaluation of the shock absorber is researched. The limit, distortion, decay rate of high-temperature and decay rate of life should meet the design requirements. Pneumatic shock absorber structure principle and performance evaluation are the base of experiment.3 Based on the introduction of five test criteria of power-showing characteristics test, speed test, multi-rate characteristics test, temperature test, life test, shock absorbers performance test system based on virtual instrument is developed. According to the test function, a control and test integration structure framework is created, which is composed with dual-servo motor control, co-acquisition of force and displacement signals. Test-bed is built, whose excitation device is connecting rod crank slider mechanism being driven by servo motor, and whose adjusting device is Screw mechanism being driven by servo motor. Through building force and displacement acquisition system which is composed by force sensor, displacement sensor, data acquisition card, computer and so on, and developing software by using LabVIEW, build a shock absorber test system is built for friction force characteristics test, power-showing test and speed characteristics test for single condition, multi-rate characteristics test. Experimental verification of the force and displacement systems acquisition system prepares for pneumatic shock absorber performance test.4 Performance test of pneumatic shock absorber is designed. Friction force and aeration test, power-showing characteristics test, speed test, multi-rate characteristics test, temperature test, life test are designed, the test content, testing process and the parameter index are established. Through testing pneumatic shock absorber both in the pneumatic state and in the non-pneumatic state, and two test results is compared.5 According to the design method and test standard of pneumatic shock absorber test, using shock absorber performance test system and other related test equipment,the results of friction force and aeration test, power-showing characteristics test, speed test, multi-rate characteristics test, temperature test, life test are gained. Through analyzing test results of pneumatic shock absorber both in the pneumatic state and in the non-pneumatic state, working characteristics of pneumatic shock absorber is gained. The results of test showed that:(1) Pneumatic shock absorber performance curve moves to negative damping force axle after inflation.(2) Pneumatic shock absorber has better low-speed friction characteristic and stable operating performance.(3) Pneumatic shock absorber has excellent anti-distortion performance at high speed, which ensures that the shock absorber reduces air-way, and improves the smoothness of suspension when car is drive over bumps at high speed.(4) Shock absorber has the characteristics of curve smooth, stable operation and more energy absorption during operation, and ensures good damping performance.Shock absorber performance test system is designed for the development and production lines. Pneumatic shock absorber testing methods and analysis of methods results provide an important basis for shock absorber R & D and production departments test Pneumatic shock absorber performance. |
