| The domestic traditional research on energy-saving of hydraulic excavator is mainly on the improvement of the hydraulic control system (such as positive, negative flow control system, LUDV control system) and the realization of the engine and load the timely matching etc. But at this stage, the research mainly focused on the application of oil electric or hydraulic hybrid system in excavator and energy recovery of high energy consumption device (boom, slewing system). But for the hydraulic excavator, the efficiency of hydraulic pump and slewing hydraulic motor is also an important aspect of affecting the energy consumption. These not only affect the reasonable configuration of power system, dissipation, power performance, economic performance, but also affect the speed of hydraulic system and the speed stability and load starting ability, which will eventually affect the operation quality of excavator. In this paper, to improve the efficiency of hydraulic pump and hydraulic motor as the main line of the research on energy-saving of medium-sized hydraulic excavator, and the main contents are as follows:1、Based on theoretical analysis of the variable displacement hydraulic motor and hydraulic pump efficiency, obtained the main influence factors. Using a23T excavator slewing motor and variable displacement pump parameters as the simulation basis, to analysis their efficiency. Find out the concrete changing trend of the variable displacement hydraulic motor and hydraulic pump efficiency with the change of system pressure, speed and volume ratio by simulation, which provide a theoretical basis for how to improve the hydraulic motor and hydraulic pump efficiency under different conditions;2、To establish the simulation model and control strategy of closed volume control slewing system. Through the analysis of simulation results and its control strategy, show:①Variable pump and fixed motor volume control slewing system can not only meet the working requirements of hydraulic excavator, but also compared with ordinary throttle slewing system it has higher energy utilization rate;②Although the fixed pump and variable motor volume control slewing system can satisfy the platform speed requirements, compared with the former control strategy it is more complex. And In the control process the engine requires to transform operating points frequently, which increase the fuel consumption;③The no-load power utilization rate of variable pump and variable motor volume control slewing system is57%and the power utilization rate of variable pump and fixed motor volume control slewing system is56.5%. Compared with them, there have no obvious difference, but they are all above he power utilization rate of the fixed pump and variable motor slewing system and a conventional throttle rotation system;④By verifying volume control slewing system in the whole simulation, the fuel consumption of closed volume control slewing system than fuel consumption of valve controlled throttle down8.16%;3、According to the analysis of variable motor efficiency and excavator slewing condition, in uniform motion stage, the efficiency of slewing motor will reduce. In order to improve the efficiency of rotary motor, the control strategy of variable pump and variable motor volume control slewing system. Simulation results show that:in the control strategy, the efficiency of hydraulic motor to maintain in80%above;4、Through the analysis of the variable pump efficiency, the excavator fine work, the transmission can be appropriate to reduce the pump speed to increase the output torque, and increase the volume ratio of hydraulic pump in as far as possible without affecting the actuator speed and engine working point transformation, which improve the efficiency of the pump, so the fuel consumption decreased by16.5%which improved the overall fuel efficiency. |
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