Slip Loader Working Device Damping System Design And Research

Skid Steer Loader, as a construction vehicle, is applied to infrastructure construction and required frequent transition. Riding comfort of working device is the key to maintain the integrity of the material within the bucket and improve efficiency in the process of transport operations. Taking ZHL3210-type skid steer loader as research object, a way to improve riding comfort of attachment is proved out by means of theoretical studies, simulation analysis, experiment evaluation. The main research works are as follows:1. Vibration control technology and the current researches about construction vehicle damping technology at home and abroad are investigated and summarized. According to the operating characteristics of skid steer loader, the causes of attachment vibration are analyzed in transport conditions. On the basis of clearly the main excitation factor and vibration transfer process, semi-active hydro-pneumatic damping solution of working device, based on changes in damping, is proposed. And hydro-pneumatic damping system of working device is established.2. Based on the analysis of hydro-pneumatic damping system, mathematical model of the system is established. Based on the model, nonlinear stiffness and damping characteristics of damping system are derived. It shows that the main structure parameters affecting damping performance of the system are the initial inflation pressure and volume of accumulator, the valve opening of proportional throttle valve, the flow cross-sectional area of one-way throttle valve. And the principle of system damping is analyzed through operating the output characteristics.3. According to damping system principle and output stiffness, damping characteristics, physical models of whole machine vibration system of adding damping system before and after are built. And dynamic mathematical models of vibration system are deduced by Lagrange equation. Based on the characteristics of working environment, D-level road surface model of random construction in general conditions and shock type road surface model of cross railway tracks in special conditions are constructed as excitation inputs of vibration system. 4. The law of the main parameters of damping system affecting riding comfort of working device, combining dynamics model of vibration system and applying Matlab-Simulink simulation software, are abtained. The kinetic parameters of hydro-pneumatic damping system are derived by simulation analysis of system conditions of D-level road model. Then system parameters and component selection are identified by the simulation parameters. Based on the damping system with determined parameters, riding comfort of working device, with D-level and cross railway tracks road surface models, is simulated and researched. The results show that damping system can well meet the requirements of smooth in D-level road conditions, but its isolation are less effective in railway tracks road conditions. So damping system of fixed parameters designed by a kind of road exists some shortcomings.5. For the lack of fixed-parameter damping system and ever-changing and complex nature of road surface in actual transport conditions, semi-active vibration control with fuzzy control is used. Then semi-active fuzzy vibration control system is established through combining with system dynamics model. And fuzzy controller is designed by MATLAB-Fuzzy tool box. Based on random road conditions and railway tracks conditions, subparagraph road surface model is built. Finally, with system without damping, fixed parameters of damping system added and semi-active vibration control system with fuzzy control, riding comfort of working device are evaluated through simulation analysis. And semi-active vibration fuzzy control system is verified effectiveness.6. Vehicle road test is carried out with ZHL3210-type skid steer loader. The results show that hydro-pneumatic damping system can work effectively in working device vibration control, the mathematical models of damping system and vehicle vibration system are correct, and semi-active vibration control scheme based on changing the system damping is reasonable.