| As an important part of the vehicle suspension,the function of shock absorber is to convert the body vibration energy generated by the uneven road surface into heat and dissipate it into the atmosphere,so as to attenuate the body vibration.The adjustable damping shock absorber can switch the damping according to the working conditions,and can improve the comprehensive performance of the vehicle,which is one of the future development directions.However,during the driving from the cold state to the hot state,the oil temperature of the shock absorber continues to rise until the heat balance,and the viscosity is opposite to the oil temperature change.The uncertainty caused by the change of oil temperature has not been considered in the study of many adjustable damping shock absorbers,and there are few solutions.For this reason,the adjustable damping shock absorber is taken as the research object.The influence of oil temperature on the damping characteristics is explored by mathematical modeling and CFD calculation.The shock absorber control strategy with temperature compensation is proposed.The main research contents are as follows:1.the structure and working principle of an adjustable damping shock absorber structure are proposed.According to its actuator scheme,the mathematical model of the flow area at different level positions is established,and the relationship between the stepping motor angle and the flow area of the flow hole is obtained.To lay a theoretical foundation for the study of temperature compensation control strategy.2.the mathematical model of the adjustable damping shock absorber and the establishment of its thermodynamic model.Based on the theory of fluid mechanics,the mathematical model of nonlinear shock absorber for compression stroke and recovery stroke is established.The thermodynamic model of the shock absorber is established by applying engineering thermodynamics knowledge.The simulation model is established by Simulink software.The results show that the damping force increases with the increase of the maximum speed of the piston rod,decreases with the increase of the oil temperature and increases with the decrease of the adjustable orifice area.In addition,taking the initial temperature of the oil at 20 °C as an example,the vehicle needs to run for 5000 s to reach the thermal equilibrium temperature of 105 °C.3.CFD simulation analysis of internal flow passage.The internal flow channel model of the shock absorber was established by ICEM CFD pre-processing software,and meshed.Then the Fluent software was used to calculate the internal flow field at 20 °C and 60 °C,and the simulation results were compared with the mathematical model results.The results show that the two agree,and the validity of the mathematical model constructed is verified.4.research on control strategy of adjustable damping shock absorber with temperature compensation.The linear weighted sum method and order relationship analysis method are used to establish the suspension performance evaluation function,and the optimal damping is optimized based on the dynamic adaptive cuckoo search algorithm.The mathematical model of the integrated adjustable damping shock absorber,the thermodynamic model and its damping force and speed,temperature As a function of the area of the orifice,an adjustable damping shock absorber control strategy with temperature compensation is proposed.In order to verify the effectiveness of the control strategy,the vehicle performance of Class B road surface,90km/h driving speed and 100°C oil temperature was simulated.The results show that the acceleration of the semi-active suspension with temperature compensation and temperature-free compensation is reduced by 19.4% and 11.7%,respectively,compared with passive suspension vehicles.In addition,when the oil temperature is the initial temperature,the adjustable damping shock absorber with/without temperature compensation has the same performance. |
PDF Full Text Request