Research On Energy-saving Characteristics Of Hybrid Hydraulic Excavator

As a typical multi-actuator industrial equipment,hydraulic excavator is often used in engineering construction.High power density,good operability and strong environmental adaptability are its advantages,but its disadvantage is that the energy efficiency of the whole machine is very low,only about 20%.It uses diesel engine to drive hydraulic pump to provide pressure oil,which is distributed through hydraulic control valve and hydraulic pipeline to control actuator action.When multiple actuators act together,if their load forces are different,the pressure is different,and the control valve port of the non-highest load actuator has throttle loss.In addition,the large potential and kinetic energy of the working devices are also dissipated in the form of throttle loss through the control valve port during the reciprocating motion.Also,the excavator load is low most of the time,making the diesel engine’s fuel efficiency low.The above three reasons are important reasons for the hydraulic excavator’s use of high-power source,high fuel consumption and large amount of heat generation.Among them,there are three reasons for the throttle loss of the control valve port:(1)Balance the overrunning load,or brake the hydraulic actuator;(2)When multiple actuators act together,if their load forces are different,and the control valve port of the non-highest load actuator has load difference effect throttle loss;(3)When a mechanically connected orifices valve is used,causing unnecessary throttle loss.In this study,independent metering control technology was used to solve the unnecessary throttling loss caused by the mechanical coupling of the control valve ports.After determining the use of the oil-electric hybrid power scheme,an energy-saving boom and swing hydraulic system were proposed.After integrating the various systems,it is proposed to reduce the throttle loss caused by the load difference through the principle of non-driven chamber pressure regulation,and to store working devices’ kinetic and potential energy in the form of electrical energy.Improve the fuel efficiency of diesel engines through the principle of torque regulation.Then,Realizing the low-pressure loss power distribution and transmission of the hydraulic excavator system and the efficient work of the diesel engine.Then,establish a system model for simulation analysis.The result shows that on the basis of ensuring the control performance,the new system can increase the pressure of the non-driven chamber of the non-highest load actuator through pressure regulation,thereby increasing the pressure of the driven chamber,reducing the throttle loss and recovering energy.It can also recover the actuators’ kinetic and potential energy.The energy-saving ratio of the whole machine to complete an excavation cycle is 13.22%.Fuel consumption has been reduced by 12.55%.Furthermore,after regulating the operating point of the diesel engine,fuel consumption has been reduced by 16.69%.Chapter 1 is the introduction,which describes the background and significance of the research,reviews the literatures,and analyzes the current research status,including the multiactuator hydraulic control system and hydraulic system energy recovery that are closely related to the subject.Chapter 2 is the system design and mathematical model of hybrid power hydraulic excavator,introduces the principle and type of hybrid power,selects the hybrid power plan suitable for hydraulic excavator working conditions,and determines the working principle of hybrid power hydraulic excavator system,the mathematical model of hydraulic components and systems is established;Chapter 3 is the simulation model part of the hybrid hydraulic excavator system.The electro-hydraulic co-simulation model of the 6-ton hydraulic excavator is established;Chapter 4 introduces the energy efficiency characteristics research of energysaving boom and rotary hydraulic system,respectively introduces the energy consumption analysis of the boom and slewing system and the corresponding energy-saving hydraulic system simulation analysis;Chapter 5 introduces the hydraulic excavation with non-driving cavity pressure control,successively introduced the system working principle,mathematical model,simulation results and diesel engine operating point control simulation research;Chapter 6 is the summary and prospect part,summarizes the research content of this dissertation,and prospects the next work.