Research On The Property Of A Magneto-rheological Pressure Control Valve And Its Application On A Vehicle Suspension

As the power transmission medium between the body and wheels, the performance ofsuspension affects the ride comfort of the vehicle directly. The conventional suspension, ofwhich the damper characteristics are ever the same, cannot perform the ideal damping forcein all kinds of conditions. While a semi-active suspension system with adjustable dampingforce, can always provide proper damping force under varied working conditions, thus thevehicle can have a good ride performance all along.A magneto-rheological pressure control valve with adjustable flow-pressure property isproposed in this paper, the research serves as a part of the semi-active suspension systemdevelopment project of a C-class car, and it’s designed based on Magneto-Rheological Fluid(MRF) squeeze mode theory. An adjustable damper with Magneto-Rheological pressurevalve is achieved by adjusting the flow-pressure characteristics of magneto-rheologicalpressure control valve, based on the property that the MRF viscosity changing with themagnetic field intensity is given. On one hand, the MRF squeeze mode can provide a largeforce with a small spool actuation range, making magneto-rheological pressure control valvehave a great pressure adjustment range; on the other hand, the magneto-rheological pressurecontrol valve use a little MRF, which can achieve fairly large shock absorber damping forceadjustment range with quite low cost. Hence it is of great significance to study themagneto-rheological pressure control valve in this paper.Based on the method of “Component-System-Vehicle”, the thesis is built upon threeparts: modeling and test for the flow-pressure property of magneto-rheological pressurecontrol valve, bench tests and modeling of magneto-rheological valve control damper and itsinfluence rules on vehicle ride performance. The first part focused on the modeling and test for the flow-pressure property ofmagneto-rheological pressure control valve. In this paper, the structure and workingprinciple of magneto-rheological pressure control valve is described firstly. Then amagnetic field finite element model of the magneto-rheological pressure control valve isestablished by Ansoft/Maxwell software, the effects on the magnetic field properties causedby structure parameters and material selection is analyzed, to complete the magnetic circuitdesign. Next, a semi-empirical model is built in this paper, considering the relationshipbetween the magnetic intensity H and the electromagnetic force FMag, the loop current I, theposition of the valve spool h, and the model results can match the Ansoft/Maxwellsimulation results very well. Then the steady-state characteristics of themagneto-rheological pressure control valve are analyzed based on the force balance of thevalve spool, considering the spring force of valve spool, the fluid pressure and the MRFsqueeze pressure. Furthermore, a detailed analysis about flow-pressure characteristics ofthe magneto-rheological pressure control valve and the mechanical property ofmagneto-rheological fluid in squeeze mode is carried out, and the flow-pressurecharacteristic curves with hysteresis characteristics of magneto-rheological pressure controlvalve are obtained, which varies with the loop current proportionally. Besides, a prototypeof the magneto-rheological pressure control valve is trial-produced and debuggedexperimentally. Although the prototype test results are not very well, which demonstratethe validity and feasibility of the magneto-rheological pressure control valve principle.The second part is the bench tests and modeling of magneto-rheological valve controldamper. The test result shows that the damping force increases with current, with thecurrent increases from0A to3A, the damping force range increases2.83times in maximumvelocity0.05m/s, and1.64times in maximum velocity0.52m/s. The magneto-rheologicalvalve control damper dynamic model is built based on BP neural network method, whichmatches the characteristic of magneto-rheological valve control damper very well, and canbe used for semi-active suspension control. The final part is the influence rules of magneto-rheological valve control damper onride performance. A1/4vehicle vibration model is established in this paper to analyze theeffects of magneto-rheological valve control damper on ride performance. With pulseexcitation and random road excitation as the input, the effect of the magneto-rheologicalvalve control damper on vehicle ride performance under acceleration damping controlalgorithm is analyzed. The results show that the magneto-rheological valve controldamper can improve the ride performance effectively.