Design And Characteristics Analysis Of A Novel Energy-harvesting Hydraulically Interconnected Suspension System

The vehicle chassis suspension needs to absorb and attenuate road vibrations to ensure good riding comfort of the vehicle,maintain the contact between the tires and the road surface,and provide support for the vehicle body to ensure that the vehicle has reliable steering stability.The motion modes are highly coupled for vehicles with traditional independent suspension,and it is impossible to adjust a particular mode separately.The hydraulically interconnected suspension(HIS)can solve the above contradiction encountered in the design process of the suspension system.It decouples the motion mode through specific connection forms,strengthens the stiffness of the vehicle's roll or pitch motion modes without affecting the riding performance,and significantly improves body attitude stability.This thesis proposes a novel energy-harvesting hydraulically interconnected suspension(EH-HIS),which can attenuate the vibration through energy recovery while considering the dynamic properties of HIS,thus increasing the energy utilization rate of vehicles.In addition,by adjusting the energy harvesting circuit,the damping of EH-HIS could be continuously adjusted to improve the road adaptability of the vehicle further.In the next,this thesis will take the suspension dynamic performances and the vehicle dynamic performances as the research objectives.Firstly,the design ideas and working principles of EH-HIS are introduced,and the pressure drop model of each hydraulic part is derived based on the rate of flow.At the same time,combined with the cylinder friction test data,the LuGre friction model is identified by genetic algorithm.A more accurate suspension output force model is derived by combining the friction model with the upper and lower chamber pressure models,which provides a foundation for the subsequent parameter optimization and characteristic analysis.Then,based on the mathematical model,the influences of initial accumulator parameters,energy harvesting unit parameters and cylinder size parameters on suspension dynamic characteristics are explored under different input excitations.The orthogonal test array is built around the parameters mentioned above,and the sensitivity analysis is conducted.The inner diameter of cylinder,external resistance,initial pressure of accumulator,gearbox transmission ratio and hydraulic motor displacement are selected as the critical parameter variables.An optimization model is established,which is constrained by the original shock absorber indicator diagram and aimed at maximizing energy harvesting power.The optimized system parameters provide a vital reference for the analysis of suspension characteristics and component selection.Then,based on different external resistance and harmonic excitation conditions,the equivalent damping coefficient,asymmetric damping coefficient,energy transfer process,energy harvesting power and energy harvesting efficiency of EH-HIS are simulated and analyzed.At the same time,key components are selected according to the optimized parameters,and a prototype of the sub-module system was also built for the bench test.The damping force and energy harvesting voltage are analyzed and compared with the simulation data.The results show that the mathematical model has high reliability and provides improvement directions for constructing the EH-HIS field test system.In addition,in order to further study the dynamic properties of EH-HIS,mathematical models of traditional linear suspension,HIS and hydroelectromagnetic energy-harvesting shock absorber(HESA)are also set up as horizontal comparison,and the damping characteristics and energy harvesting characteristics of each suspension are compared and analyzed under harmonic excitation.Subsequently,a complete 14-DOF vehicle model is built based on a nonbearing body chassis.Combined with random road vibration conditions,double line shifting test conditions and linear braking test conditions,the ride comfort,handling stability and energy harvesting characteristics of each suspension system are discussed and compared.Finally,a half-vehicle EH-HIS system is designed for the field test.With this system,the rear axle suspension system of the non-bearing body chassis is modified and upgraded.After assembling the transducers and data collection systems,the construction of the field test platform is completed.The vehicle with EH-HIS is tested under flat road surface,sand road surface,and double line shift test conditions.The vertical acceleration,roll angle and energy harvesting voltage are extracted as the leading evaluation indices to compare the dynamic response of the vehicle equipped with EH-HIS and original shock absorbers,respectively.The actual energy harvesting effect of the EH-HIS is also explored.