| With the rapid development of automobile in the direction of light,high speed and heavy load,the vibration of automobile seats is becoming more and more intense,which has a great impact on ride comfort.How to improve ride comfort by enhancing the adaptive capacity of automobile seat suspension has become one of the key issues that urgently needed to be solved in the field of automobile engineering.Although the active control can achieve good comfort,the energy consumption is relatively large and the application is limited.So,the semi-active control system which has variable stiffness or damping can be applied to improve ride comfort.Some high-end vehicles have been equipped with the magnetorheological seat suspension due to excellent perfprmances.Linear type magnetorheological dampers are mostly used in these intelligent seat suspensions.Although linear dampers can achieve good control performances,they have complicated process and high cost.In addition,they have problems such as small adjustable range and large occupied space.Compared with linear magnetorheological dampers,rotary magnetorheological dampers have the advantages of compact structure,wide adjustable range and relatively simple process.Therefore,they have been attracted a lot of attention from research scholars.Due to the limitations of maximum shear yield strength and working mode of the magnetorheological fluid,the torque density of rotary magnetorheological damper is small at present,and it is difficult to be directly applied to the vibration control of automobile seats.Therefore,it is necessary to start from the working mode of the magnetorheological fluid and explore the design theory and key technology of the magnetorheological rotary damper for automobile scissor seat suspension.Based on this,the details of content are as follows.1)In order to improve the energy consumption characteristics of magnetorheological fluid,a novel helical flow mode of magnetorheological fluid is proposed from the perspective of increasing the flow length.The formula for calculating the pressure difference of the helical flow channel is deduced.The charateristics of helical flow mode in annular channel was analyzed by comparing the traditional flow mode in annular channel and in spiral channel with fixed angle.The influence of the axial length,gap thickness and flow rate on the pressure difference of the channel is analyzed.The ways to increase the pressure difference and pressure difference ratio of the channels are pointed out respectively for the linear damper and rotary damper applying helical flow mode.2)In order to realize the high torque output in the limited space,a magnetorheological rotary damper structure scheme for automobile scissor seat suspension is proposed based on the helical flow working mode.The magnetic induction intensity prediction model is established by finite element method and response surface method.The maximum torque and adjustable range are used as optimization targets.The main structural parameters of the damper are optimized by non-dominated genetic algorithm with maximum torque and adjustable range as the optimization objective.3)Based on the results of structural parameters’ optimization,the rotary damper with helical flow mode were processed,assembled and tested.In order to describe the hysteretic characteristics of helical flow rotary damper,two modeling methods are proposed based on skeleton curves.One method is based on skeleton curves and phase lag factor.The other is based on the skeleton curve and hysteresis division method.The dynamic models were identified by particle swarm optimization and compared with each other.A dynamic model which can accurately describe the strong nonlinear dynamics of the MR damper is obtained.4)In order to analyze the feasibility of the semi-active seat suspension with helical flow rotary magnetorheological damper,the simulation and experimental research on the seat suspension system based on magnetorheological rotary damper are carried out.The dynamic model of the scissor seat suspension is established and the effects of load bearing mass,spring stiffness coefficient and Coulomb damping on the dynamic characteristics of the seat suspension are analyzed.A simplified semi-active control model of seat suspension is derived from dynamic model.A semi-active controller of the magnetorheological seat suspension is designed.The open-loop control of seat suspension system under sinusoidal stationary-frequency excitation,sweep frequency excitation,impact excitation and random excitation is simulated and analyzed.Furthermore,the semi-active vibration control experiment of the magnetorheological seat suspension based on the electric vibration table was carried out,which verified that the magneto-rheological seat suspension can improve the control quality. |
