| Oil pump plays an important role in the lubrication system of the automobile engine. With the usage of oil pump, certain amount of lubricating oil are pressurized and ceaselessly delivered to friction surface of the engine moving parts for lubrication. And the pump also maintains circulation of lubricating oil in the lubrication system. However, part of the engine power will be consumed in the oil pump running process, which will influence the dynamic performance of the engine. As a typical example for the development of the oil pump in the future, variable displacement gear type oil pump will not only reduce the engine power consumption effectively but also achieve the effect of energy conservation and emissions reduction. Therefore, it is of great significance to carry out the dynamics characteristics research of variable displacement gear type oil pump.In this thesis, a model of variable displacement gear type oil pump is taken as the research object, and its dynamics characteristics are studied. The main research contents are summarized as follows:1) Based on the multi-rigid dynamics theory and the usage of virtual prototype technology, the multi-rigid-body dynamics model of variable displacement gear type oil pump is established according to the structure parameters, performance index and working characteristics of the research object provided by enterprise. Based on the kinematics and dynamics analysis of virtual prototype model, the difference of input and output angular velocity of variable displacement pump under different working conditions are studied, the gear transmission ratio is calculated and analyzed. The fluctuation on the dynamic contact force between gears under low speed and high speed is discussed, and error on exciting frequency of gear is analyzed by contrast with theoretical value. The effectiveness of the established simulation model is verified by variable displacement gear type oil pump comprehensive performance bench test.2) Micro deformation of transmission parts of oil pump will appear under high speed situation, which can produce unsteady shock created by nonlinear inertial coupling. In order to solve this problem, variable displacement pump driving gear and driven gear of the transmission part is set as the flexible body based on rigid-flexible coupling dynamics theory and finite element method. According to the actual working condition, the variable displacement gear type oil pump rigid-flexible coupling dynamic model is established, and its effectiveness is verified through bench test. The dynamic loading of the research object between gears is analyzed under the steady conditions and transient conditions, and the difference between multi-rigid model, rigid-flexible coupling model and theoretical analysis is explored.3) Based on the rigid-flexible coupling dynamics model,the loads and boundary conditions are set, and vibration model of variable displacement pump is established. The frequency range and sampling frequency of the variable displacement pump is set according to its actual working condition. Meanwhile, there is also the analysis of parameters that affect the vibration characteristics of the variable displacement gear type oil pump such as system mode, frequency response functions and transfer functions.Through the dynamic characteristics research of the variable displacement gear pump, the related parameters such as dynamic contact force of research object is identified and analyzed under different conditions, and the parts that are easy to cause fatigue failure and local resonance are explored. The results provide the technological foundation for the dynamic optimization of the product, it can also lay the foundation for the design and development of the key parts which transmit load. |
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