| With the advantages of large piling energy, high efficiency, and low environmental pollution, hydraulic pile hammer is widely used in the foundation construction of the modern engineering. Hydraulic crawler chassis is the key device to support and transfer of the machine. It’s the unavoidable energy loss caused by mechanical friction, leakage and hydraulic pressure relief that heat the oil and raise the temperature of the crawler chassis hydraulic system. High oil temperature not only affects the system performance, and even leads to system malfunction and invalid. Therefore, forecast and analysis the temperature characteristics of the hydraulic control system are of great theoretical and practical engineering significance during designing of the hydraulic pile hammer crawler chassis.Firstly, the development and the domestic and international status of the research of the hydraulic system temperature characteristics were introduced. Based on the operational requirements, the control method and program of the crawler chassis hydraulic system were confirmed. A preliminary analysis of the heat production in the system was taken, considering the work principle of the system.Secondly, the commonly used traditional RC network theory was analysized. Combined with two conservation laws, adopted the thermodynamic control body temperature calculation method, the effect of pressure change on the temperature was taken account of and an improved modeling program was proposed, considering the interaction of temperature and pressure. Based on this moldeling theory, the temperature and pressure dynamic models of the hydraulic system for the ZCY20-6hydraulic pile hammer crawler chassis were established.Thirdly, dynamic changes of system pressure and temperature were analyzed by solving the mathematical models with the MATLAB software. The simulation results showed that:the dynamic temperature changes are associated with that of pressure and the temperature of designed hydraulic system fluctuates with the changes of pressure and steadily rising after the pressure is stable when walking and climbing. To solve the problem some system improvement programs were proposed and all of them were simulated with the models based on the improved RC network modeling, which demonstrate the programs are feasible.Finally, the experiment of hydraulic pile hammer crawler chassis was completed. The testing results show that the simulation results are in agreement with the experimental results, which verified the correctness of improved theory and effectiveness of simulation study, and so that theoretical basis for safety work of hydraulic pile hammer crawler chassis is provided. |
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