Simulation Research On Heating Of Working Mechanism Of Fully Hydraulic Luffing Boom Tower Crane

With the rapid economic development of China today,in order to meet the needs of high-rise and super high-rise buildings,large and super large tower cranes that can provide a lifting torque of more than 2000t·m gradually occupy the market.The full hydraulic tower crane is the first choice for large-scale tower cranes due to its high hydraulic transmission power density,easy to obtain larger output torque and stable operation.Boom-type luffing tower cranes requiring less rotating space are more suitable for operations in narrow spaces,and can meet the requirements of tower crane cluster operations.Full hydraulic boom tower cranes are mostly closed hydraulic systems,and diesel engines are used as power input.However,due to the circulation characteristics of the oil,the closed heat dissipation performance is not as good as the open system.Serious problems of hydraulic system temperature rise often occur during heavy load and continuous operation,which not only causes waste of resources,it also has a serious impact on the working performance of the tower crane.Under the background that the country vigorously promotes the concept of energy saving and emission reduction,it is of great significance to the research on the heating of the hydraulic system of the working mechanism of the full-hydraulic boom tower crane.This thesis takes the hydraulic system of a certain type of full-hydraulic boom tower crane as the research object.Aiming at the heating problem of the lifting mechanism and the hydraulic system of the slewing mechanism,a simulation study is carried out.Through the components of the thermo-hydraulic library,THCD library,Thermal library,mechanical library,and plane mechanical library in the AMESim software,the thermo-model of the hydraulic system at the component level are built.They are more realistically simulate the actual variable process of pumps and motors and the temperature rise of the hydraulic system.By using the plane mechanical library model to replace the traditional signal input,the mechanical-hydraulic integrated thermo-hydraulic model of the lifting mechanism and the slewing mechanism are built.The simulation results are more consistent with the actual working state.Through the comparison of simulation curves and samples,the output characteristics of the pump and motor models are verified.Based on the power loss method and thermodynamics theory,the model is verified correctness.The simulation is carried out under the set simulation conditions.The simulation results show that:(1)Under the single action conditions,the hoisting mechanism completes 5 working cycles and runs for 2200 s.The temperature of the hydraulic system reaches 83.3°C,which exceeds the hydraulic system of the construction machinery.The maximum working temperature is 80℃.The slewing mechanism completes 10 working cycles,running for 1200 s,and the temperature of the hydraulic system is 26.6℃.(2)Under the combined action condition,the hoisting mechanism and the slewing mechanism alternately complete 5 working cycles,running for 1700 s,the temperature of the hydraulic system of the hoisting mechanism is 76.9°C,and the temperature of the hydraulic system of the slewing mechanism is 65.8°C.By comparing with the single action condition,the system temperature rises more rapidly under the combined action condition.(3)By changing various parameters that affect the temperature of the hydraulic system,performing simulations and comparing the system temperature curves before and after the parameter changes,it is clear that the excessive temperature rise of the hydraulic system is caused by insufficient heat dissipation power in the natural state,which proves the necessity of installing forced air-cooled radiator in closed hydraulic system.It also provides guidance for the operation and use of the tower crane.Provide guidance for energy-saving design of hydraulic system by analyzing main heat-generating components.For the heat that cannot be reduced,a thermoelectric power generation type energy-saving cooling oil tank is designed to recover the heat energy,and the converted electric energy is used for the heat dissipation of the oil tank to achieve the purpose of energy saving and emission reduction.In this thesis,the plane mechanical library model is used to replace the traditional mechanical and signal model to realize the mechanical-hydraulic integrated thermo-hydraulic simulation.The simulation results are more in line with the actual working temperature rise of the tower crane.The application of the research conclusions in this paper is not only limited to the design of the closed hydraulic system of the tower crane,but also provides guidance for the design of the hydraulic system of other construction machinery.