| The controlled semi-active magnetorheological(MR) shock absorber was able to automatically adjust its damping force with the road and the load changing. That would help the suspension reach the request of damping match, the driving safety and the riding comfortableness of the cars would be balanced. Semi-active MR shock absorbers had the advantages of wide range of adjustable damping force, rapid responding time, low-power consumption, and so on. The study of MR shock absorber is the main development of semi-active suspension. This paper proposed a novel Magneto-rheological Fluid(MRF) shock absorber with gas volume compensation using floating piston, aiming at solving the problems of inadequate compensation of MRF shock absorber, the non-smooth transition of damping force when the piston changes its direction. It investigated the structure of the MRF damper, the key process technology, the parameters of magnetic circuit, the calculating method of damping force, testing and analyzing the force-stroke character of MRF damper, and so on. The details of the work were as follows:①The status of the MR suspension among the vehicle was analyzed, and the developments of the MR technology all over the world were reviewed. It proposed a novel Magneto-rheological Fluid(MRF) shock absorber with gas volume compensation using floating piston, aiming at solving the problems exist in normal MRF dampers.②The overall structure of MRF shock absorber with gas volume compensation using floating piston was designed according to the parameter requirements of the Chang-An® car suspension system. It mainly researched the design and the parameters of the outer cylinder of MR shock absorber with monotube and single ended damper, Self- Guided piston with micro-bypass using flow mode, the connection structure of piston and piston rod, the structure of high pressure gas volume compensation with floating piston, the sealing and guiding of operating cylinder, the coil winding and leading structure in the piston.③The calculating method of Magnetic flux density in the damping channel gap of MRF shock absorber was investigated using the model of magnetic circuit. Comprehensive analysis of the materials’ BH characteristics and the using cost, and the model of magnetic circuit were studied to determine the materials of magnetic core, the parameters of magnetic core, the number of turns of the coils, the diameter of conductive wire, and so on. Simulation research was conducted using the software of finite element analysis, and its results proved that the theoretic analysis of magnetic circuit is reasonable and effective. And the parameters of magnetic circuit were optimized with ANSYS analysis, in order to reach the demands of the design.④The MRF performances were tested using the Anton Paar MCR301 Rheometer and the VSM HH-15. The basic parameters of biplastic model were determined according to the result of MRF performance. The flow fields for every parts of MRF damper were analyzed by using the biplastic model, and the relationship function between the flow volume and hydraulic pressure difference between the both side of the piston was obtained. The calculation method was determined with comprehensive analysis for damping force produced by the piston head and the floating piston, and the friction force between all parts of the MRF shock absorber.⑤The electromagnetic piston components, the sealing and guiding components of piston rod, the floating piston components, the operating cylinder and outer structure were manufactured, and then the prototype of MRF shock absorber was processed. The force-stroke characteristics of MRF shock absorber prototype were tested according to the QC/T545-1999, the bench test of cylinder shock absorber of vehicle, using the WDTS vibration test machine.The result of the test indicates that the dynamometer card of the shock absorber is full, and the theoretical damping force values of the shock absorber under various excitation current are accord with the test data. It proved that the theoretical analysis was right, and the result reached the expected designed goals. |
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