| As an important engineering machinery,hydraulic excavator has the characteristics of high energy density,compact structure and large working range,which can complete complex mining conditions and diversified forms of operation.So it is widely used in various construction and mineral exploitation,such as water conservancy,road,housing,railway and so on.However,the working device of the hydraulic excavator,which is very heavy,frequently rises and falls under the drive of the hydraulic cylinder during normal operation.And the gravitational potential energy gathered during the lifting process is dissipated by throttling of the control valve in the form of heat energy during the lowering process,which results in huge energy waste.Therefore,the full recovery and utilization of the energy lost in this part is very important for improving the energy efficiency of the hydraulic excavator and reducing the energy consumption of the whole machine.In view of the above problems,this thesis presents an energy-saving system of excavator boom based on hydraulic-gas energy storage balance,and applies it to 36 t large hydraulic excavator for research.The system adopts three-chamber hydraulic cylinder and hydraulic accumulator.On the basis of maintaining the original mechanical structure,the system uses three-chamber hydraulic cylinder to replace the single rod hydraulic cylinder of the original boom system,and uses the hydraulic accumulator to recover and directly reuse the potential energy of working device,so as to improve the reutilization rate of the potential energy recovery of the working device.This thesis constructs a joint simulation model of boom energy-saving system of the excavator,including the diesel engine,the hydraulic system and the working device.The simulation of original boom system and boom energy-saving system is carried out respectively.The operation characteristics,the energy consumption characteristics of the engine and the hydraulic system are compared and analyzed,and the test verification is carried out to further optimize the parameters of the accumulator.The main research work of this paper is as follows:1.The analysis of the original boom system.According to the working principle of the existing hydraulic excavator’s boom system,the energy consumption of the system in the process of the boom descending and lifting is theoretically analyzed respectively,and the diagram of energy transfer chain is drawn to determine the energy saving route of the original boom system according to the process of energy transfer and loss.2.Energy-saving system of excavator boom based on hydraulic-gas energy storage balance.The energy-saving system based on hydraulic-gas energy storage balance is put forward,and the mathematical model of the key components of the boom energy-saving system is established and its parameters are determined.The energy consumption of the boom energy-saving system in the process of the boom descending and lifting is concretely analyzed respectively to study the energy saving of the boom energy-saving system.3.The construction of simulation model.The multi body dynamic model,hydraulic system model and diesel engine test model of the hydraulic excavator working device are constructed in Simulation X,and the three parts of the model are connected together to build a joint simulation model of the hydraulic excavator’s original boom system and the boom energy-saving system.4.The analysis of operation and energy consumption characteristics.The operation characteristics and energy consumption characteristics of the original boom system and boom energy-saving system are simulated and analyzed respectively based on the constructed model.The simulation results show that the boom energy-saving system based on liquid gas energy storage balance reduces the energy consumption of the main pump by 53.8%,the energy consumption of diesel engine by 48.5% and the fuel consumption of diesel engine by 31.7%.The test platform is built,and the feasibility and good energy saving of the boom energy-saving system are verified through experiments.5.The analysis of the influence of the hydraulic accumulator’s parameters.The influence of different pre charging pressure and hydraulic accumulator volume on the charging and discharging characteristics of hydraulic accumulator is analyzed.The simulation results show that the energy recovery and reutilization rate of the hydraulic accumulator increase with the increase of pre charging pressure and decrease slightly with the increase of the volume of the hydraulic accumulator. |
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