Research On The Design Theory And Performance Simulation Of A Magneto-Rheological Hydraulic Engine Mount

With the development of science and technology, the introduction of high-performanceengines, the continuous improvement of road conditions, coupled with the continuouslowering of the mass of the car itself, the NVH problems caused by engine vibrationattracted more people’s attention. In order to improve the ride comfort and the overall qualityof the car, the semi-active and active engine mount performance of which is better than thetraditional engine mount emerges. On the other hand, the emergence of smart material suchas the magneto-rheological fluid accelerates the course of development of the engine mount.This paper presents an engine mount based on the flow model of magneto-rheologicalfluid. When exposed to an applied magnetic field, Magneto-rheological fluid change from afree-flowing state into a semi-solid state in milliseconds, as a result the magneto-rheologicalfluid shear yield stress increases. This engine mount adjusts the dynamic characteristics of itsown by controlling the intensity of the input current, to meet the needs of the enginevibration isolation. This paper describes the characteristics of magneto-rheological fluid,produces a magneto-rheological engine mount which can be used for dynamic characteristicstest, and analyzes the key components of the magneto-rheological engine mount-themagnetic structure, and establishes models of the dynamic characteristics of the enginemount, two-freedom-degrees and six-freedom-degrees models.Firstly, the paper describes the development process and ideal vibration isolationcharacteristics of engine mount, introduces the properties of the magneto-rheological fluidand its technical applications in the automotive, civil facilities. Secondly, I design amagneto-rheological engine mount which can be used for dynamic characteristics test, andanalyze a key part of the engine mount-the magnetic structure-with the finite elementmethod, and it provides guidance for magnetic circuit structure design of the magneto-rheological engine mount. The critical factors affecting the magnetic field strengthsuch as current, channel gap are analyzed to find out a more precise magnetic field strengthrelationship for analysis of the dynamic characteristics of the magneto-rheological enginemount.Then, I introduce the working mode of the magneto-rheological fluid briefly, use thebond graph method to establish a model of magneto-rheological engine mount based on thetraditional engine mount hydraulic model. Also I deduce the state equation of the low andhigh frequency engine vibration respectively. The parameters of structure and input currentare considered to have an impact on the dynamic characteristics of magneto-rheologicalengine mount. Experimental study of magneto-rheological engine mount shows the dynamicstiffness and damping angle varies with frequency, which verifies the correctness of thesimulation model. It provides preliminary theoretical analysis to the structure design ofengine mount.Finally, considering the suspension, I build the simulation model of two-degrees-freedom system with the method of bond graph. Also I take fuzzy control as a controlstrategy, and the result shows that the vibration isolation performance of themagneto-rheological engine mounts are superior compared to the conventional ones.