| As the power system of diesel locomotive,the vibration of power unit will directly affect the reliability and safety of its structure and the comfort of passengers.The traditional rubber passive vibration isolation has reached the limit in the optimization of boundary conditions,and it is difficult to continuously improve the vibration isolation effect.It has become an inevitable requirement to further improve the vibration isolation efficiency by using the parameter adjustable double-layer vibration isolation system.In this paper,the vibration characteristics of the power unit of internal combustion motor car under all working conditions are studied.Finally,two semi-active control strategies based on MR damper are proposed,and the semi-active control simulation system and semi-active control experimental platform are established.The simulation and experimental results show that the two semi-active control strategies proposed in this paper can greatly improve the vibration isolation performance of the system under all working conditions.Firstly,this paper analyzes the basic structure and common evaluation indexes of the double-layer vibration isolation system,theoretically discusses the influence of the change of the primary vibration isolation parameters on the vibration isolation performance,determines the vibration isolation scheme of reducing the stiffness of the primary vibration isolator and increasing the adjustable damper in this paper,and the dual optimization objectives of the vibration isolation performance in this paper.Based on this scheme,the variable universe fuzzy control theory,the speed signal measurement of internal combustion engine The condition monitoring method of internal combustion engine and vibration isolation element,and the sampling frequency is optimized according to the monitoring target.Then the spring isolator required in this paper is redesigned and optimized,and a new spring isolator is processed.The dynamic performance of MR damper is experimentally studied.The forward and reverse nonparametric models of MR damper are identified by genetic neural network method,and the accuracy of the model is determined.Secondly,the 18 DOF multi rigid body system is simplified in the direction of dumping torque,and the two DOF rigid body system simulation model including control force is established;According to the dual optimization objective of vibration isolation performance,a hybrid variable universe fuzzy control method is proposed.Based on the two degree of freedom semi-active control system,the control method is verified by frequency sweep excitation method;In order to better test the application of hybrid variable universe fuzzy controller in double-layer vibration isolation system,combined with Adams and Simulink software,an 18 DOF rigid flexible coupling semi-active control system with flexible intermediate frame is established,and the simulation research is carried out under frequency sweeping condition and stable condition;According to some pre experimental results,a piecewise optimal control strategy of system damping varying with working conditions is proposed.Then,in order to be used in the actual model,a complete system for semi-active control and condition monitoring is developed by using c# language.Finally,in order to more truly verify the accuracy of the two semi-active control methods(hybrid variable universe fuzzy control and piecewise optimal control)and the developed system,the optimized new spring isolator and the developed control and monitoring system are used to replace the traditional rubber spring isolator on the double-layer vibration isolation test bench,Through the comparison with the traditional rubber vibration isolation scheme,the effectiveness of the two active control schemes in the actual use process is tested.The results show that the initial weight and threshold of BP neural network are optimized by using the global optimization ability of genetic algorithm.The forward and reverse nonparametric models of MR damper established by this method have high identification accuracy and can accurately describe the dynamic characteristics of MR damper.Based on the idea of ceiling and floor control,a hybrid variable universe fuzzy controller suitable for the whole working condition of the unit is proposed.In the simulation verification,the vibration intensity of the unit is small in the low frequency band,the system is stable,the dynamic reaction is effectively reduced in the high frequency range,the vibration isolation performance is improved,and the vibration control of the whole working state of the unit is realized.The accuracy and applicability of the semi-active control and condition monitoring system developed in this paper are tested in the experiment.Under the start-up and shutdown conditions,the rubber passive vibration isolation scheme and the two semi-active control methods proposed in this paper are experimentally compared.The two semi-active control schemes proposed in this paper can keep the system stable during the start-up process and achieve the same effect as the traditional rubber vibration isolation scheme.During the shutdown process,the vertical vibration velocity of the rubber vibration isolation scheme has an obvious resonance peak,and the maximum peak value is13.291mm/s,The two semi-active control schemes proposed in this paper have no obvious formant in the shutdown process.The maximum vertical vibration velocity in the hybrid fuzzy adaptive control scheme and the segmented control scheme is reduced by about27.59% and 10.34% respectively.Through the experiments under 8 stable operation conditions,the vertical vibration speed and vertical dynamic reaction force of the three experimental schemes are qualitatively and quantitatively analyzed.The vertical vibration speed of the rubber passive vibration isolation scheme is slightly higher than that of the other two semi-active control schemes,but the vertical dynamic reaction force of the two semi-active control schemes is significantly reduced under medium and high frequency operation conditions compared with the rubber vibration isolation scheme,Among them,the vertical dynamic reaction force of hybrid variable universe fuzzy control scheme is reduced by 49.66%,and the vertical dynamic reaction force of segmented control scheme is reduced by 48.30%.The research results of this paper can provide a new technical route and method for further improving the overall vibration and structural vibration control of diesel locomotive double-layer vibration isolation system,and provide a useful reference and guidance for the vibration control research of other power equipment. |
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