Study On Car Magneto-rheological Fluid Shock Absorber With The Structure Of Mono-tube And Charged-gas Bag

The traditional passive shock absorbers of cars reduce road excitation passively viaestablished inadaptable structure design, instead of automatically adjustingdampingforce in accordance with real road cases. A magneto-rheological (MR) shockabsorber is able to improve this issue, by adjusting the real-time responsive dampingforce to achieve a good effect on reducing road excitation. There is a few defects ofcurrent dampers, e.g. for binoculars MR shock absorber-the difficulty in design, andeasy jam of bottom valve caused by long term standing. Another example is monocularshock absorber whose volume compensation component is not very effective, floatingpiston is difficult to seal and matching precision is highly required. In this case, a novelmonocular inflatable compensated MR shock absorber is proposed to help fix theseproblems. The main work in this study contains design of structural parameters, keytechnology study of production, analysis of magnetic circuit model, derivation ofdamping force, and field test, result analysis and discussion.Details are as follows:(1)Review the applications of MR technology, development of automotivesuspension, together with the development of shock absorbers domestic and abroad;investigate the disadvantages of traditional MR shock absorbers, and propose the novelideas and their significances.(2)With the technical requirements of the Chang-An car suspension system,design a MR shock absorber based on monocular inflatable structure with mixed mode;design the parameters of outer cylinder，compound guide，two annular dampingchannels and inflatable capsule based on the magnetic characteristics and workingprinciple of MR fluid.(3)Establish the magnetic circuit model using dynamic magnetic theory;optimizethe magnetic parameters to maximize the performance of MR fluid; determine the corematerial and deduce the expressions of magnetic flux density and magnetizing current;obtain the analysis diagram of magnetic saturation in damping channel gap and ironcore by means of ANSYS software to verify the validation of the magnetic circuitdesign.(4)Compare the pros and cons of various constitutive models of MR fluid andobtain the parameters of H-B model by fitting the experimental data; establish thebalance equations of annular damping channel based on flat model and axisymmetric model respectively; deduce the flow velocity distribution expressionby usingH-B modelparameters and boundary conditions; deduce the damping force in annular channelusing the pressure gap; obtain the gaseous pressure equation from the damping forceexpression of the balloon compensation component; finally, obtain the total outputdamping force expressionof the MRshock absorber.(5)Analyze and discuss the key processing technology of MR shock absorbers;describe in detail the test method, conditions and system; investigate force-stroke andvelocity characteristics of the prototype; analyze the causes of the errors. The resultshows the theoretical values based on plate model are in good agreement with the testones.(6) Summarize all the work and innovations; state the issues to be further studiedin the future.