Study On Vibration Control Of Engine Based On Magneto-Rheological Fluid Isolators

Engine has a wide frequency, multi-sources and multi main frequency vibration when it runs. It's not only to affect normal operation of equipment and instrument but also to decrease riding comfort and have a serious effect on surrounding environment. Rubber mount and hydraulic mount are applied widely to engine mount at present and their performances of vibration isolation are not good enough, so semi-active mount of good performance is paid more attention by many researchers. There is nonlinear for magneto-rheological (MR) semi-active mount and it is difficult to control MR mount by establishing an accurate model. Based on complex vibration exciting of engine and combined with nonlinear characteristics of MR mount, it is important practical significance to study control method of fuzzy logic for engine vibration isolation.On the basis of theoretical analysis that engine generate complex vibration, vibration characteristics of diesel engine is tested systematically with experimental method. A dynamic model of engine vibration isolation system is established. The effect of transmissibility of vibration isolation system is analyzed in theory when mount parameters of engine are changed. A controllable MR fluid mount based on disk squeeze mode is designed according to installation technology of diesel engine mount. Indictor characteristics of MR mount is tested at national bus quality inspection center. PID and fuzzy logic control methods are proposed. Data acquisition and real time control hardware of engine vibration control is designed using CompactRIO embedded real time controller of national instrument. The relevant data acquisition and control programs are compiled. Finally, vibration and isolation control of engine is carried out in different conditions and then the data of PID and fuzzy control based on MR mount is analyzed and processed. The experimental results compared with passive rubber mount are analyzed.Through the studies, the main vibration exciting sources of engine are second order reciprocating inertia force and overturning moment. There is nonlinear relationship among cycle dissipation power, exciting frequency and exciting current of MR mount. There is reasonable that dynamic exciting force which is transferred from engine to support is regard as evaluation index on engine mount vibration isolation effect. The fuzzy control strategy is feasible that isolator has a demand for large stiffness and damping on low-frequency vibration, small stiffness and damping on high-frequency vibration. The fuzzy controller of double input and single output is feasible that second order exciting force and acceleration for input, control voltage for output. The experimental results show that dynamic exciting force which is transferred from engine to support can be decreased based on control system of MR mount and the effect of vibration isolation on low speed is better than high speed compared with rubber mount. The effect of fuzzy control is better than PID control.