Study Of Damper Characteristic Of Two Typical Types Of Twin-tube Hydraulic Auto Shock Absorbers

With the rapid development of vehicle industry,requirement of the performance exhibited by the vehicles become higher.How to manufacture cars that provide safer and more comfort experience pose great challenges for the vehicle industry.Serving as an important part of vehicles,the suspension’s function mainly consist of transferring the force and torque that act on the wheels and vehicle body and defusing the impacts to the vehicle body causing by the uneven roads which lead to the attenuation of the vibration so that the cars can speed smoothly on the roads.Typical suspensions consist of spring components,guiding devices and shock absorbers,and the shock absorbers are the most essential parts.Currently,the damper force is provided mainly by the twin-tube hydraulic shock absorbers in the suspension.The characteristic of shock absorbers plays a key role in guaranteeing the ride comfort and handling stability of vehicles,safety for the passengers.Traditionally,shock absorber industry depends on experiments to identify parameters when designing shock absorbers,and then make some amends when necessary through experiments.But when dealing with variable types of shock absorbers,the trials of modifying parameters and experiments become complex and tedious,which lead to the result of long manufacturing period and high cost.More importantly,the accuracy and result stability of shock absorbers obtaining from this kind of experiments cannot be guaranteed.Thus,simulating the damper characteristic with software to predict and optimize the performance of shock absorber during design phase bears great importance.The research of this paper is based on the cooperated project---’Study of Damper Characteristic of Auto Shock Absorber’---between Northeastern University and Zhongxing Shock Absorber Company in Zhejiang China.As follows are the main work of this paper:First of all.based on the content of the contract,a thorough investigation about auto shock absorber was carried on.Combining with the real shock absorber from the company,a deeper understanding and grasp of the overall structure and working principle of hydraulic shock absorber were obtained.According to what have learned,the flow of oil was analyzed and the physical model of shock absorber was established.The necessary knowledge of Fluid Mechanic was introduced,and some reasonable hypothesis was made considering some practical factors.Second,theoretical study of two typical type of auto shock absorber was carried on.The two types were nut-valve hydraulic twin-tube hydraulic auto shock absorbers and spring-valve hydraulic twin-tube hydraulic auto shock absorbers.The key problem,that was the study of deformation of valve discs,was specified.The opening of the valve discs directly influenced the flow of oil in the shock absorber chambers,thus determined the damper force that the damper could provide.The differential equation of opening of nut-valve and spring-valve was deduced using the Small Deformation Theory,and the relationship between valve opening and the pressure in different chambers were obtained.The equivalent thickness of multiple discs theory was introduced.Basing on what have discussed before,the mathematical model of auto shock absorber was build,and the damper characteristic was calculated to verify the theoretical study.Third,the experimental research of two type shock absorber was carried on.The experiment condition,equipment,and experimental content were introduced.The damper characteristic of auto shock absorber including velocity characteristic,displacement characteristic and multiple velocity characteristic was obtained.The comparison between theoretical calculation and experimental performance was drawn,and the result showed that they matched very well.Lastly,the influence law of different key parameters of the damper characteristic was studied.Finally,the development of application.After the accuracy of the theoretical study was verified,the development of application was started to shorten the design and production period.The tool of this development was MATLAB GUI module.The GUI contained the convenience of user-defining and the excellent numerical calculation of MATLAB.The application in this paper contained multiple tags,such as Piston Valve,Base Valve,Other Parameter,Character Curve and Optimal Design.It aimed at the calculation of damper characteristic for different kinds of shock absorber under different parameter and at the same time,optimize the damper characteristic.By reestablishing the differential equation of discs deformation,the more reasonable mathematical model of damper characteristic is built.By comparing the theoretical results and experiment performance and optimizing the damper characteristic,the more accurate results are obtained.The research in this paper is of great practical importance and the application developed can be put into practical production process directly.