Vibration analysis of hydro-pneumatic suspension system based on drive motor excitation force

Abstract: Hydro-pneumatic suspension has good nonlinear elastic and damping characteristics and is widely used in engineering vehicles. Accurately establishing a mathematical model of hydro-pneumatic suspension systems and a vehicle dynamics model is important to analyze the dynamic characteristics and vehicle ride comfort. Scholars usually study the vibration of a suspension system only based on the excitation of road roughness. However, engineering vehicle suspension is directly connected to the wheel drive motor shell, and the vibration forces can directly act on the suspension. It is necessary to consider coupling excitation of the drive motor and road roughness to analyze the practical vibration characteristics of the engineering vehicle suspension system. This paper took the pneumatic suspension vibration system in a mine dump truck as its study object. The method of describing the movement of the real vehicle pneumatic suspension systems approach was proposed based on the combined effect of motor excitation and road roughness. According to the vehicle system installation, the author drew out a system model, conducted various stress analysis, and created the system equations of motion. The gas elastic force term could be seen as an ideal gas processing and pressure was equal to the suffered loads when the suspension was in a static equilibrium position. The damping force term was calculated using a thin-walled holes mathematical model. The relative displacement was taken as an argument to establish the damping force equation. According to the geometry and electromagnetic parameters of the driving motor, its finite element analysis model was established by software to obtain the flux density distributions. The vertical excitation force of asynchronous motors was solved by a Maxwell-stress method. The numerical solution of the electromagnetic force at the given speed was calculated and imported into the system equations. Road roughness was the major incentive to the driving of the vehicle and it could be described by a stationary stochastic process theory. In this paper, a white noise filtering method was adopted to simulate random road. This paper made a simulation comparison on the ideal sine road. The vehicle tests on an ISO D level typical road and obstacle negotiation proceeded to verify the validity of the theory. The results showed that on a typical sinusoidal road surface, the difference was most obvious in the initial time after considering the motor excitation. The system output amplitude increased by about 10% and took a longer time to stabilize. The suspension output elastic force changed significantly, and the two frequencies tended to finally coincide. The vehicle tests showed that the high-frequency excitation force made the system acceleration power spectrum become larger under various conditions, and the coupled excited vibration model was more consistent with the measured data. Power spectrum analysis showed that acceleration increased significantly in the exciting force frequency and should not be ignored. In the evaluation of suspension ride comfort, human acceptable vertical amplitude decreases with increasing frequency. High-frequency vibration effects will be more obvious and should not be ignored. The comparison of measured data and simulation verified the effectiveness of the motor incentive model in the pneumatic suspension system. To ensure the ride comfort of the whole vehicle with an in-wheel motor, motor excitation force and road excitation should be considered simultaneously in the suspension design.