Investigation On Lightweight Design For The Integrated Electro-hydraulic Power Unit

The traditional electro-hydraulic power unit consists of an electric motor and a hydraulic pump connected by a coupler. The discrete electro-hydraulic power unit has many disadvantages, such as complex structure, higher weight, lower efficiency and the potential for external leakage. However, the integrated electro-hydraulic power unit investigated in the paper integrates an electric motor and a hydraulic vane pump, and possesses the advantages to achieve compacted structure, lower noise and leakage free. It has half size and much lower weight, compared to the traditional electro-hydraulic power unit. And the lightweight design for the integrated electro-hydraulic power unit is a significant trend.Aiming at the lightweight design of the integrated electro-hydraulic power unit, the theoretic analysis and the numerical simulation used ANSYS are applied to study the lightweight casing. The intensity and the rigidity of the original casing are analyzed, and the lightweight aluminum alloy casings with different models are also simulated. In consideration of the pressure fluctuation acting on the outlet cover, the outlet cover has the danger of fatigue damage, so the fatigue analyses are done. The research results show that the original casing has higher intensity, rigidity and life, which suggests that the lightweight design has too much room. And the intensity, rigidity and life of aluminum alloy casings with different models are analyzed. In the end, the optimized lightweight material is6061aluminum alloy, which also has the lower price and lower density. The weight of6061aluminum alloy casing is63.6%lower than the original casing in the integrated electro-hydraulic power unit, suggesting that the lightweight design has impressive effect.The main content of this thesis consists:In chapter1, the background, purpose and significance of this thesis is raised. The research and development around the world on the electro-hydraulic power unit and lightweight design are introduced. And then the applied software ANSYS is introduced. In the end, the main research contents of this paper are summarized.In chapter2, the structure of the integrated electro-hydraulic power unit is introduced, and working principle is explained. The intensity, rigidity and fatigue are introduced applying theory of static analysis. The principles of lightweight design, the lightweight materials and the connection of different materials are stated. In chapter3, the static analysis on the original casing of the integrated electro-hydraulic power unit is done. The calculated model is built and all the parts on the casing is analyzed by using ANSYS to obtain the intensity, rigidity and fatigue life. The simulated results suggest that the original design can be improved.In chapter4, this paper chooses four models of aluminum alloy to rebuild the casing, and the size of some parts is reduced. The lightweight casings are simulated to obtain the performances. Taking the yield strength, density, price into account, the optimal lightweight material is6061aluminum alloy, which makes the weight of the casing in the power unit reduce70.1%in weight.In the end, some conclusions and achievements about this thesis are summarized, and the future research proposals are suggested.