变排量齿轮泵三维内流场分析

发布时间：2018-05-16 06:41

本文选题：变排量齿轮泵 + 流场仿真　；参考：《上海工程技术大学》2016年硕士论文

【摘要】：变排量齿轮式机油泵因其润滑效率高、燃油消耗率低等优点,成为发动机机油泵的主要趋势。但是由于变排量齿轮泵非全啮合状态的存在,造成了其与传统定排量齿轮式机油泵的不同,使定量泵存在的空化和困油问题在变量泵中更加突出,从而导致润滑效果降低。为提高变排量齿轮泵的总体性能,并为进一步的优化设计提供借鉴。本文建立变排量齿轮泵CFD模型,分析了变排量齿轮泵的空化特性及流量特性,对其困油区域卸荷槽进行了优化,并研究了齿轮副设计参数对流体输运特性的影响规律。主要研究工作包括:第一,针对变排量齿轮泵在不同转速时齿轮对应不同啮合长度的特点,运用定量分析的方法对变排量齿轮泵建模并进行仿真分析,得出变排量齿轮泵在不同转速工况时的啮合宽度公式,并通过试验对模型及公式进行验证。基于验证的变排量齿轮泵模型进行仿真计算,对其空化特性进行分析,得出变排量齿轮泵的空化区域主要发生在进油腔齿轮啮合区域,并进一步研究不同影响因素对其空化的影响。然后,针对变排量齿轮泵三种主要的间隙泄露进行分析,研究不同的间隙对泵流场的影响,并得出轴向间隙泄露对流场的影响最大。第二,重点研究变排量齿轮泵的困油现象,并对卸荷槽进行了优化。通过分析变排量齿轮泵的困油过程,对困油容积进行求解,为变排量齿轮泵的困油分析提供理论依据。通过对变排量齿轮泵CFD模型的仿真计算,对困油区域的压力脉动进行分析,同时研究不同影响因素对困油区域压力脉动的影响。基于变量泵的运行机理设计契形卸荷槽结构,并运用正交实验方法选出最优卸荷槽形位,通过对比加新卸荷槽前后的仿真计算结果验证了卸荷槽的有效性。结果显示在相同的流量情况下,靠近吸油腔的困油区域压力脉动降低9.9%,靠近排油腔的困油区域压力脉动降低8.3%。第三,通过研究变排量齿轮泵的齿数、模数、压力角、啮合齿宽、重叠系数、变位系数以及齿顶高系数等齿轮副参数对泵流体输运特性的影响,得出齿轮副参数对流体输运特性的影响规律。并根据规律重新设计齿轮副,通过仿真计算分析重新设计齿轮副的变排量齿轮泵,计算结果得出新齿轮副使泵的排量提升3.3%,流量脉动系数降低2.1%。本文旨在建立变排量齿轮泵的流体仿真和优化流程,所提出的方法与得出的结论,可推广应用于其它类似变排量齿轮泵的设计,能够为变排量齿轮泵的理论研究与设计提供一定的技术支持。
[Abstract]:Variable displacement gear pump has become the main trend of engine oil pump because of its high lubricating efficiency and low fuel consumption. However, because of the incomplete meshing state of variable displacement gear pump, it is different from the traditional constant displacement gear engine oil pump, which makes the cavitation and trapped oil problems of the quantitative pump more prominent in the variable pump, resulting in the reduction of lubricating effect. In order to improve the overall performance of variable displacement gear pump and provide reference for further optimization design. In this paper, the CFD model of variable displacement gear pump is established, the cavitation and flow characteristics of variable displacement gear pump are analyzed, the unloading slot in the oil trapped area is optimized, and the influence of gear pair design parameters on the fluid transport characteristics is studied. The main research work includes: first, according to the characteristics of variable displacement gear pump with different gear speed corresponding to different meshing length, a quantitative analysis method is used to model and simulate the variable displacement gear pump. The meshing width formula of variable displacement gear pump under different rotational speed conditions is obtained, and the model and formula are verified by experiments. Based on the verified model of variable displacement gear pump, the cavitation characteristics of variable displacement gear pump are analyzed, and the cavitation region of variable displacement gear pump is obtained. The influence of different factors on cavitation is further studied. Then, the three main clearance leaks of variable displacement gear pump are analyzed, and the influence of different clearance on the flow field of the pump is studied, and the effect of axial clearance leakage on the flow field is found to be the greatest. Secondly, the oil trap of variable displacement gear pump is studied, and the unloading slot is optimized. By analyzing the process of oil trap of variable displacement gear pump, the volume of trapped oil is solved, which provides a theoretical basis for the analysis of oil trap of variable displacement gear pump. Through the simulation of CFD model of variable displacement gear pump, the pressure pulsation in the oil trapped area is analyzed, and the influence of different factors on the pressure pulsation in the oil trapped area is studied at the same time. Based on the operation mechanism of the variable pump, the structure of the unloaded slot is designed, and the optimal unloading slot configuration is selected by orthogonal experiment. The effectiveness of the unloading slot is verified by comparing the simulation results before and after the new unloading tank is added. The results show that under the same flow rate, the pressure pulsation in the oil trapped area near the suction chamber is decreased by 9. 9%, and the pressure fluctuation in the oil trapped area near the drain chamber is decreased by 8. 3%. Thirdly, the influence of gear pair parameters, such as tooth number, modulus, pressure angle, mesh width, overlap coefficient, displacement coefficient and tooth top height coefficient, on the fluid transport characteristics of variable displacement gear pump is studied. The influence of gear pair parameters on fluid transport characteristics is obtained. According to the law, the gear pair is redesigned, and the variable displacement gear pump is redesigned by simulation calculation. The result shows that the new gear pair can increase the displacement of the pump by 3.3% and decrease the flow pulsation coefficient by 2.1%. The purpose of this paper is to establish fluid simulation and optimization flow of variable displacement gear pump. The proposed method and conclusions can be extended to other similar variable displacement gear pump design. It can provide some technical support for the theoretical research and design of variable displacement gear pump.
【学位授予单位】：上海工程技术大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U464.137.1

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