Energy-saving And Control Performance Research Of The Hydraulic Hybrid Excavator Based On CPR

The increasing energy crisis and environmental deterioration phenomenon is becoming the key problem for preventing the healthy development of the world. The energy saving research for excavators is not only benefit for reducing the energy consumption, but also making an example for other type construction machines. Moreover, the hydraulic hybrid technique is promising because the high power density and the energy recuperation potential. However, the state of the art about this technique is mostly constrained with the sub system, esplecially lack of the control strategy or the performance research from the whole aspect. Hence this technique is not popular until now. Based on the project of “key technological research on the energy-efficient hydrostatic hybrid system” supported by National Natural Science Foundation of China, this paper focuses on the hydraulic hybrid excavator based on CPR and invistages the whole machine design and the key problems during the practical process.Firstly, the characteristics between the hydraulic and the electric hybrid excavators are analyzied by introducing the exact model based on the state of the art of the hybrid excavators. Then, the hydraulic hybrid excavator based on CPR is chosen as the research object and the development of the technique is stated. Furthermore, the Hydraulic Hybrid Excavator based on Common Pressure Rail combined Switched Function is presented and the principle is explained. The whole machine model is constructed by using the theory analysis combined with the test rig testing method for the critical components. And the matching process of the new elements is finised. Then, some critical parameters are necessary for simulation but hard to get, such as the friction coefficient and the rotational inertia, are identified by using the single testing of the arm, and the compound control action is used to prove the result. Moreover, the optimal mataching for the critical elements is analyzied by using the dynamic programming algothim under the minimum fuel consumption object during the standard cycle.The new system can save the oil consumption as37%by comparing the original LUDV excavator. Furthermore, the method by using lower relief pressure is presented after analyzing the energy distribution of the new excavator. Moreover, the hierarchical controller combined with control strategy and control method is designed, especially three kinds of practical control strategies are studied for the middle layer and the ASPS is the best one.The FSMI controller is designed to enhance the performance under the lower pilot control pressu caused by adopting the energy saving control stragety. For the new sensor which is easy to disturb, especially for the gyro, the observe-based controller is investigated and the result shows that the control performace is acceptable even under the condition while the sensor fails. Finally, because the cylinder controlled by the hydraulic transformer has the strong coupling and nonlinear problem, the controller combined the active pressure feedback and fuzzy principle is presented to enhance the robust performance without concering the interior structure.In the end of the thesis, both the test rig and the prototype machine experiments are conducted. Firstly, the original5t excavator is modified by adding the data acquisition system and the standard working cycle is tested to prove the simulation result for the energy distribution analysis. Moreover, the swash plate position experiment by using the method, that the engine drives the pump/motor and the relief valve is simulated as the load, is finised to test the effictiveness of the control algorithm. Then, the swing is modified according to the CPR theory and the feasibility is tested under the conditions of light load and overload respectively. Furthermore, the test rig for the cylinder controlled by the hydraulic transformer is constructed. The experiment including angle control of the port plate and the position control of the cylinder is tested, the result shows the method can complete the task in spite of the accuracy is low, however, it is appropriate for the construction machine such as excavators because this kind of machines does not require the high accuracy.