Analysis And Optimization Of Ride Comfort Of Powertrain Mounting System For A Three-wheeled Agricultural Vehicle

Agricultural multi cylinder three wheel vehicle has the advantages of beautiful cab appearance,powerful power output,high traffic ability,small turning radius and low price brought by high chassis.Due to the impact of national announcement policies,agricultural vehicles can only use three cylinder engines.With the youth of rural labor,the demand of users has also been improved.Users generally feedback that three cylinder engines have problems such as high vibration and noise,especially the impact of light truck market,which has seriously affected the sales volume of agriculture multi-cylinder tricar wheel produced by our company.In order to improve the vibration reduction performance and driving comfort,the main design ideas are as follows.1.By referring to the relevant data of vehicle mounting system design,vehicle ride comfort analysis,NVH and modal analysis,the basic principle analysis of vibration isolation is studied,the relationship between vibration transmission rate and frequency ratio is understood,the structural layout design of mounting system,the theoretical calculation and verification of static,dynamic stiffness and size structure of mounting rubber pad are studied,and the mounting system is tested under the condition of known load.The natural frequency and stiffness parameters of the rubber pad are calculated.2.Through the measurement of the original parameters of the whole vehicle and engine mounting system,the parameters of each important part of the whole vehicle are obtained,such as the coordinate parameters of each mounting particle,the mass of the engine assembly,the center of mass and coordinate parameters,the moment of inertia and the inertial product,etc.,and the stiffness parameters of the engine mounting rubber pad and the gearbox mounting rubber pad are measured.3.The NX,MATLAB and Adams are studied.The body assembly,frame assembly,power assembly,suspension assembly and body assembly of the whole vehicle are modeled.The parameters measured in the front are assigned to them.According to the actual assembly situation,the connection relationship between the subsystems is established,and the whole vehicle model is finally obtained.After obtaining the whole vehicle model,using the advanced simulation command,the modal analysis of the mounting rubber pad,the mounting bracket and the whole vehicle model is carried out.The first six modal modes of the mounting rubber pad and the stress analysis model of the mounting bracket are obtained respectively,and the first six modal modes of the whole vehicle are obtained.According to the stiffness and coordinate position of the mounting rubber pad,the mass,the center of mass and the moment of inertia of the power assembly,the decoupling rate of the mounting system is calculated with MATLAB.4.Through the calculation,the external size and rigidity of the engine mount rubber pad and the transmission mount rubber pad are adjusted,and the modal analysis of the adjusted state is carried out again.The first six modes of the optimized rear mount rubber pad and the vehicle model are obtained respectively,and compared with the mode before the change.5.Using the existing vibration test equipment of the company,the vibration test of the whole vehicle was carried out on the front,rear fulcrum,seat slide,steering wheel,rearview mirror and other important parts of the mounting rubber pad on the agricultural vehicle.According to the test procedure,the vibration acceleration and isolation rate of these important parts are obtained.Through the comparison of the parameters before and after,the results of the optimization of the suspension system are confirmed.