Research On Vibration Characteristics Of Commercial Vehicle’s Air Spring Seat With Auxiliary Air Chamber

During the driving of commercial vehicles,the driver must bear the low frequency and high intensity vibration directly transmitted by the seat.Working in this environment for a long time will cause damage to the health of the driver and affe ct the work efficiency.As the last way of vibration transmission,the seat of the vehicle directly determines the vibration intensity acting on the driver.The seat is connected to the vehicle by the relatively separate part,and this part it’s easy to modify and doesn’t affect other parts of the whole vehicle.Air spring seat which with an additional air chamber,as a semi-active seat,it combines the advantages of active seat and passive seat,and is one of the future commercial vehicle seats.Therefore,it’s having great significance to study its vibrational characteristics.The random signals of the road were used as the excitation,to study the vibrational characteristics of the air spring seat with additional air chamber.Compared with the sinusoidal excitation used in the traditional study methods,the random excitation of the road can reflect the actual working condition of the seat.Based on the filtered white noise method,this paper studied the random excitation signals of the road and established the seat dynamics simulation model.The two models are used to study the vibrational characteristics of the seat when the road’s grade,vehicle’s speed,driver’s weight and throttle damping coefficient change.Finally,build an experimental system to study the influence of above variables on the vibrational characteristics of the seat,and verified the simulation results.The main work of this paper are as follows:(1)Based on the filtered white noise method,the road random excitation signal model was established in Simulink to generate time-domain signals of road random excitation displacement under different grades of road and vehicle speed.The theoretical analysis of vehicle’s vibration model is based on the two degree of freedom model of wheel and vehicle body,therefore the time-domain displacement excitation signal of the floor under different road excitation signals was generated in Simulink.(2)Based on the excitation signals and the two degree of freedom model of wheel and vehicle body,the vibration differential equation was constructed and solved.Therefore,the natural frequency,damping ratio,vertical stiffness and the equivalent damping coefficient,etc.of the seat system parameters,their expression of are obtained.According to this parameter expression,the vibration characteristics of the seat were not only related to the structure and geometric parameters of the seat,but also depend on the stiffness characteristics of the air spring,the damping coefficient of the orifice,and the weight of the driver,etc.(3)Based on the theoretical analysis and the mechanical model of the seat system,the dynamic simulation model of the seat system was established in the dynamics simulation software Adams.Based on the simulation model,the effects of random excitation of the road,driver’s weight and orifice damping coefficient on the vibration characteristics of air spring seats were studied.(4)Based on the experimental system of seat vibration,studied the influence of the above variables on the characteristics of the seat vibration,and verified the simulation results through the vibration experiment of the seat.The main conclusions of the paper are as follows:(1)If the road grade,vehicle speed,and driver’s weight was changed,the natural frequency range of the seat will always keep between 2.44-3.54Hz,which satisfies the frequency avoidance requirement of the human body frequency range of 4-12Hz and the vehicle body frequency range of 1.2-2Hz.Under common road grades,the main frequency of the seat acceleration is below 3 Hz when the vehicle speed changes.(2)The relationship between the damping coefficient of the orifice and the root mean square value of the seat acceleration,under different road grades,vehicle speeds and driver’s weight were studied.The optimal throttle damping coefficient of the seat under the different working conditions was obtained,the value range was 1.50-2.27N·s/mm.If the driving condition changes,the seat damping performance can be optimized by controlling the opening of orifice.In this paper,the application of road random excitation signal to the vibration characteristics of air spring seat with additional air chamber was studied,reflected the vibration characteristics of the seat under actual working conditions.At the same time,it also has certain reference significance for the study of vibration characteristics of other forms of air spring seat or active and passive seat.