Analysis And Research On The Trapped Oil Phenomenon Of External Involute Gear Pump

External involute spur-gear pump with its simple structure, small volume, light weight, good suction and many other advantages is been widely used in mechanical equipment. This paper takes the gear pump which frequently used in engineering machinery as the research object, through theoretical calculation, simulation and virtual measurement to analyze the trapped oil features and the method to eliminate the phenomenon of trapped oil in external involute spur-gear pump. And I hope this paper could make contribution to the research and development on the gear pump which with no trapped oil, high pressure, high speed and super silent in the future.First of all, this paper from the existing research results to analyze the external involute spur-gear pump’s structure characteristics to find the causes of the phenomenon of trapped oil and make careful analyze on two stages of trapped oil.Secondly, through the calculation of external involute spur-gear pump’s trapped oil area and volume, I find the mathematical relationships between trapped oil area and pressure angle, between trapped oil volume change rate and turning angle, between trapped oil volume change rate and the gear contact ratio.Then, with the help of Fluent software’s powerful dynamic simulation in flow field, this paper wants to simulate the internal flow filed of the external involute spur-gear pump’s calculation model. This is in order to truly reflects the gear pump’s phenomenon of trapped oil as much as possible, and vividly represents the specific conditions of the gear pump’s flow field when the phenomenon of trapped oil is happening.In addition, this paper analyzes the changing rule of the trapped oil area on a specific external involute spur-gear pump’s area. By 2D virtual measurement method to obtain the trapped oil areas in different angle, and draw the variation curve of the trapped oil area. Besides, this paper analyzes several traditional methods to eliminate the phenomenon of trapped oil, and put their effects into comparison.Finally, Based on the existing research on elimination of gear pump’s trapped oil, combining the new theory and new technology, this paper proposes two new methods to eliminate the phenomenon of trapped oil( External oil-way method and Combined slots method).And this paper has carried on a detailed introduction to the working principle of the two new methods, has respectively evaluated their effects on eliminate the phenomenon of trapped oil, also has made a simple introduction on possible problems will be happened when the above two new methods is being used.