Riassunto analitico
External gear pumps are a type of positive displacement pump that utilizes the meshing of external gears to pump fluid. It consists of two gears, a driving gear, and a driven gear, which rotate in opposite directions. The fluid automatically fills the inter-teeth volume chambers at the inlet, while the rotation of the gears transfers this fluid from the low-pressure side to the high-pressure side. During this process, the fluid in the inter-teeth volume chambers is pressurized gradually by the leakages coming through the gaps from the high-pressure side to the low-pressure side.
This thesis uses a numerical model that utilizes lumped parameters to analyze the meshing process of external gear pumps and motors. All mathematical analysis models will be completed in MATLAB, including gear modeling, meshing, and rotation simulations, to obtain the corresponding inter-teeth spaces. The model represents the inter-teeth space using a two-volume approach, customized for both pump and motor units. This is achieved through structural analysis of high-pressure recesses and low-pressure recesses, and considering the corresponding side flow area, backlash flow area, and inter-teeth backlash flow area between the volumes. Equations for porting areas at different rotation angles are derived from this analysis. The model calculates inter-teeth pressures by solving the incompressible and isothermal continuity equation simultaneously applied to both volumes. This equation is combined with the classical turbulent orifice equation. Finally, this thesis compares and analyzes the influence of different gear rotating speeds and different outlet pressure conditions. It is assumed in this thesis that the gear design follows an ideal model, and leakages caused by the gap between the gear and the cabin flank are ignored.
Many commercial software programs currently available allow for quick and convenient design of gear pumps, providing rapid results. However, this thesis takes a different approach by mathematically modeling gear pumps in MATLAB. This approach provides designers with a deeper understanding of the pump's operating principles. It offers valuable insights into the factors influencing the distribution of inter-teeth pressures during the meshing process of external gear pumps and motors, as well as the impact of various design parameters on pump performance. The research findings are significant for optimizing gear design and enhancing the operational efficiency and reliability of these devices.
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