Abstract:In order to study internal leakages, especially axial leakage, in an involute internal gear pump with high pressure, the flow in the gap channel between gear rim and pump casing, i.e. the axial leakage, was analyzed, and a simplified geometrical model was established. The pressure distribution along the circumferential direction in this channel was got by performing numerical simulations in Fluent. Based on that, the axial leakage flow rate was calculated, and validated experimentally. It was shown that the axial leakage is significant and it is the main factor that influences the volumetric efficiency of the pump. The flow rate in the axial leakage depends on the tolerance and eccentricity; moreover it increases with increasing clearance, but decreases with increasing eccentricity. In order to make sure the pump can maintain a high volumetric efficiency under a high pressure, the size of the gap between gear rim and pump casing should be controlled strictly in design phase. Meanwhile, the direction of eccentricity should be controlled carefully by figuring out a reasonable design for the radial thrust balance device. As a result, a part of the axial leakage flow rate can be reduced as well by ma-king use of change in eccentricity under a high pressure.
[1]Choi T H, Kim M S, Lee G S,et al. Design of rotor for internal gear pump using cycloid and circular-arc curves[J]. Journal of Mechanical Design, 2012,134(1):011005.[2]李玉龙,刘焜. 内齿轮泵实体CAD的集成方法[J]. 农业机械学报, 2007,38(2): 106-110. Li Yulong, Liu Kun. Method research on solid CAD applied in internal engagement involutes gear pump[J]. Transactions of the Chinese Society for Agricultural Machinery, 2007,38(2): 106-110.(in Chinese)[3]Inaguma Y. Calculation of theoretical torque and displacement in an internal gear pump[J]. Koyo Enginee-ring Journal, 2006, 1001: 70-76.[4]Hall J H. Internal gear pumps: Your second choice for thin liquids[J]. World Pumps, 2005(469): 32-37.[5]Ballard L E, Hoffner C. Selecting internal gear pumps for difficult duties[J]. World Pumps, 2005(462): 26-27.[6]杨杰,傅理琦.提高齿轮泵额定压力的研究[J]. 液压气动与密封, 2008(1): 29-32. Yang Jie, Fu Liqi. Research on enhancing rated pressure of gear pump[J].Hydraulics Pneumatics & Seals,2008(1):29-32.(in Chinese)[7]Sasaki H, Inui N, Shimada Y, et al. Development of high efficiency P/M internal gear pump rotor(megafloid rotor)[J]. Technical Review:English Edition, 2008, 66: 124.[8]Xu Hong, Yang Lijuan, Jing Baode, et al. Research of internal leakage theory model in the exterior meshing gear pump[C]//Proceedings of the International Confe-rence on Intelligent Human-Machine Systems and Cybernetics, 2009: 331-334.[9]Mimmi G C, Pennacchi P E. Involute gear pumps versus lobe pumps: A comparison[J]. Journal of Mechanical Design, 1997, 119(4): 458-465.[10]毕晴春, 凌俊杰,张策,等. IGP型高压低噪声内啮合齿轮泵结构特点分析[J]. 机床与液压, 2010,38(2): 50-52. Bi Qingchun,Ling Junjie, Zhang Ce, et al. Analysis on structure feature of IGP high pressure low noise internal gear pump[J]. Machine Tool & Hydraulics,2010,38(2):50-52.(in Chinese)[11]Slodczyk D, Stryczek J. Designing a pumping system of gear pumps featuring the involute internal gearing[J]. Key Engineering Materials, 2012, 490: 64-75.[12]张国贤. 高压内啮合齿轮泵[J]. 流体传动与控制, 2011(6): 57-58. Zhang Guoxian. High pressure internal gear pumps[J]. Fluid Power Transmission and Control, 2011(6): 57-58.(in Chinese)[13]马涛, 戴惠良,刘思仁. 基于Fluent的液体动静压轴承数值模拟[J]. 东华大学学报:自然科学版, 2010,36(3): 279-282. Ma Tao, Dai Huiliang,Liu Siren. Numerical simulation study on liquid Hybrid bearing based on Fluent[J]. Journal of Donghua University:Natural Science,2010,36(3): 279-282.(in Chinese)[14]罗骥,吴盛林,袁子荣,等.内啮合齿轮泵内部泄漏流量的建模与试验[J]. 机床与液压, 2005,33(8): 106-107. Luo Ji,Wu Shenglin,Yuan Zirong,et al. Modeling and experiment of leakage flow in internal gear pump[J]. Machine Tool & Hydraulics, 2005,33(8): 106-107.(in Chinese)[15]李玉龙,孙付春. 齿轮泵齿侧间隙与卸荷槽间距关系的定量分析[J]. 农业工程学报,2012,28(22):63-68. Li Yulong, Sun Fuchun. Quantitative analys is of relationship between backlash value and distance of two relief grooves in external gear pump[J]. Transactions of the Chinese Society of Agricultural Engineering, 2012, 28(22): 63-68.(in Chinese)