Arc Gear Pump Operating Characteristic Analysis

Because of simple structure, reliable work performance, long service life and low price, gear pump is widely used in hydraulic systems of mechanical products just like automobile, vessel, airplane, etc. The arch gear pump proposed in this paper is a new type of gear pump. It consists of a pair of involute arch cylindrical gears with the same geometric parameters, transmission shafts, pump body and pump covers. As arch gear pair transmission has advantages as following:great meshing performance, bigger overlap coefficient, low noise, powerful bearing capacity, long service life and without axial force and so on, it has obvious advantage to build gear pump.This paper discusses the meshing characteristic of arch gear pair and confirms the geometric parameters, correct meshing conditions. In addition, contacting profile equation, meshing line equation, tooth surface equation and contact radio calculation are deduced. On the basis of analysis, it could be concluded that a pair of arch tooth surfaces could achieve line contact and oil sealing, so arch gear pair can be used to construct gear pump and ensure the normal operation.Oil trapping character of arch gear pump is analyzed in this paper and the relation between geometric parameters of arch gear pair when oil-trapped phenomenon doesn’t occur is discussed, that is the stable transmission of arc pear pump could be guaranteed and oil trapping phenomenon could be eliminated by reasonable setting of gear parameters. Through theoretical calculation and analysis on instantaneous flow and flow pulsation of spur tooth gear pump and arch tooth gear pump, it could be concluded that the flow pulsation of arch tooth gear pump is less than that of spur tooth gear pump if they have the same main geometry parameters.Finally, this paper introduces the related mathematical model of computational fluid dynamics, discrete format and numerical algorithm inside the pump. Three-dimensional modeling software is used to build arch gear pump model, meshing software of Gambit is used to deal with entity and create grid, fluid dynamics analysis software of Fluent is applied to analyze internal flow field of pump by numerical simulation way, obtaining the flow pressure of convective, velocity vector diagram and transient volume flow variations at last, and the flow pattern of flow field is analyzed too. The pressure and velocity distribution of the flow field obtained are similar to their theoretical analysis. The comparison of flow field numerical simulation analysis and spur gear pump results shows that transient flow pulsation characteristic of arch gear pump is better than that of spur gear pump.