Research On Energy Saving For Hydraulic Excavators Based On Hybrid And Regeneration

Hydraulic excavators (HE) have been paid much attention in the field of energy saving and environment protection, for the reason of their large application quantities, high fuel consumption and bad emission. So high efficiency and energy saving have been one of the main aims to be pursued by excavator manufacturers. Currently, the researches on energy saving of hydraulic excavators mainly concentrate in three aspects: improving the performance of working components, reforming the hydraulic system and ameliorating the situation of power match for diesel, hydraulic system and actuators. It is difficult to go any further for energy saving to reform the components, which has played an important role in raising system efficiency. The hydraulic system, with low efficiency in nature, especially with too much energy loss on the main valves, should be regarded as an important research object. System efficiency can be raised through power match, for the output energy of engine can be utilized adequately. But the improved space is restricted on account of the low engine efficiency due to the fluctuation of its operating state. So, it turns into another important research direction of the energy saving of HEs to improve the working state of engine by means of hybrid technology.As the research object, a 20-ton class HE driven by double-pump is modeled within Simulink and SimMechanics environment of MATLAB. Based on the study of energy distribution, the schemes of parallel and series hybrid systems are evaluated, according to their fuel consumption, equipped power of working components and working parameters. The parallel hybrid system with the capacitor as energy accumulator and the project of energy regeneration with hydraulic motors are explored in detail, combining theoretical analysis, computer simulation and experimental research. Finally, a scheme with a series of energy saving methods, such as parallel hybrid, separately driving, electric motor driving swing and the energy regeneration with hydraulic motor, is presented and synthetically evaluated.The main contents of each chapter are summarized in the following:In Chapter 1, the significance of the research on energy saving for HEs is discussed, and the state-of-the-art of energy saving research methods for working components, hydraulic system and power match of HEs are introduced. Some characteristics and shortcomings of these methods are analyzed. An energy-saving scheme, based on the improvement on the working manner of hydraulic system and the adoption of hybrid system, is brought forward. The research contents of the project and the work that determine to be dealt with in the dissertation are summarized.In Chapter 2, a mathematical model of a 20-ton class excavator is established, and a simulation model is built up with Simulink and SimMechanics toolboxes of MATLAB system. The energy-flow of the HE is analyzed, and the output power of engine and the...