The study on theoretically estimating variable axial clearance in a medium or high pressure external gear pump is rare yet, thus a dynamics model for determining such a clearance was established in the paper based on an analysis on forced acted on a floating axial sleeve (side plate), which consisted of the pressure in squeezed film, the outside compensated forces on the sleeve, the pressure in trapped oil and the working oil pressure. Then variable axial clearances were iteratively estimated from the model in a meshing cycle by using the Runge-Kutta method. Subsequently, an analysis on the influence of compression ratio, different distributions of working oil pressure and trapped oil pressure on the clearance value was conducted. The results show that the axial clearance is about 0.13 mm in all the cases, and it is consistent with the actual value. The greater the total force of oil pressure due to the different distributions of operating oil pressure at the same compression ratio, the smaller the axial clearance. As the other conditions remain unchanged, the higher the compression ratio, the smaller the axial clearance. Moreover the operating oil pressure and compression ratio have a significant impact on the clearance, but the trapped oil pressure just has slight effect on it. Generally, in a medium or high pressure external gear pump the axial clearance really shows less variable, so that the mean value of the variable clearances can be applied in design to simplify subsequent calculations.
Jing Baode,Yang Lijuan,Lu Shuang. The research of contaminant abrasion on external gear pumps [C]／／Proceedings of the Control and Decision Conference. Shenyang: Northeastern University Press， 2009: 3090-3093.
Houzeaux G,Codina R.A finite element method for the solution of rotary pumps[J].Computers & Fluids, 2007,36(4):667-679.
Wang Hailan,Shao Hanqiang.Study of axial clearance leakage and compensation of gear pumps [J].Journal of Academy of Military Transportation,2005,7(4):31-33.(in Chinese)
Yang Jie.Research of bearings axial floatability for high pressure gear pump［J］.Chinese Hydraulics & Pneumatics,2010 (2):8-10.(in Chinese)
Casoli P, Vacca A, Berta G L, et al. A CFD analysis of the flow field in the lateral clearance of external gear pumps[C]∥Proceedings of the 11th Scandinavian International Conference on Fluid Power.Linkoping: Linkoping University Press, 2009:786-794.
Morgridge D, Evans H P, Snidle R W, et al. A study of seal lubrication in an aerospace fuel gear pump including the effects of roughness and mixed lubrication [J]. Tribology Transactions, 2011, 54(4):657-665.
Eaton M, Keogh P S, Edge K A. The modeling, prediction and experimental evaluation of gear pump meshing pressures with particular reference to aeroengine fuel pumps [J]. Journal of Systems and Control Engineering, 2008,220 (5):365-379.
Li Yulong,Sun Fuchun.Theoretical analysis of volumetric efficiency and phenomenon of trapped oil under centrifugation in external spurgear pump [J].Transactions of the Chinese Society of Agricultural Engineering,2011,27(3):147-151.(in Chinese)