Energy-saving Research For Loaders Based On Hydraulic Transformer

Loader is one of the most important construction machineries. The characteristics of loader are overloading, low-speed, high fuel consumption. Secondary regulation technology of constant pressure rail and a new secondary regulation element: Hydraulic Transformer(HT) were used on hydraulic system of wheel loader based on hydrostatic transmission technique with secondary regulation in order to improve the situation of high fuel consumption. The main content include that:1. Structure Improvement of Hydraulic TransformerThe efficiency of Hydraulic Transformer is one of the most important factors that affect effect of Loader energy saving.According to the design deficiency of IHT, a structure of double port plates hydraulic transformer (DPPHT) was proposed. The forces of chief elements inside hydraulic transformer were analyzed. The conclusion was drawn that the structure of double port plates can solve the questions of unbalanced distribution for radial force and cylinder vibration.2. Anlysis with Theory of Power Bond GraphThe power bond graph was so mature that it can accomplish system model with figure and power flow.The relation of linearity and nonlinearity can be treated easily with power bond graph because the closeness to fact for the theory. The bond graph model and mathematical model of HT were established. The dynamic response of HT load port used with Matlab/Simulink indicates requirements for actual working conditions were met and further research of hydraulic transformer was achieved. 3. Construction of New Hydraulic System and Building Models of Chief ElementsThe new hydraulic system of loader based on secondary regulation constant pressure rail was established from what we had been studied above. Most hydraulic valves were omitted and throttle loss were decreased compared with current hydraulic system. Mathematical model of pump, accumulator, overflow valve were built in order to prepare for next simulation.4. Action Simulation of Loader and Anlysis of Energy SavingAiming at the work condition of fliping materiel and lifting materiel with booms, the model of hydraulic transformer was built. The models of new hydraulic system and current hydraulic system were built with software named AMESim. The result of curves between flow, pressure, power and time indicated the output power number of new hydraulic system was reduced clearly to 27%. New hydraulic system can recover potential energy of bucket so that the life of loaders will be rised.5. Research on Control StrategyThe nonlinearity is the significant characteristic of hydraulic system. The control strategy based on load pressure so that accurate control and fast response can be achieved. The controller was designed used control algorithm of neural network-incremental PID. The control strategy proposed in this article was suitable for nonlinearity hydraulic system compared the signal response of square wave, step, sine.6. Bench Test and ProspectsThe characteristic experiments of hydraulic transformer on flow, pressure, ratio of transformation,efficiency had been done on the hydraulic constant pressure rail bench. Dynamic characteristics and energy saving effect confirmed the feasibility of new hydraulic system actually. Real train test and full hydraulic drive loader will be the research emphasis.