A kind of multi-gear pumps based on higher-degree elliptical gears is proposed

and their flow characteristics are discussed herein.The radial size of the higher-degree elliptical gear varies with its rotation angle continuously

the volume between pump shell and the meshed gears changes during rotation of the gears

and the changes can be used to send liquid forward.Although the structure is simple

the higher-degree elliptical gear pumps with 2 gears have great flow fluctuations

this is unapplicable to use.Adding another gear to the 2 gears pump

a 3 gears pump is obtained.When the central gear under the certain conditions in the 3 gears pump

the flow from one side of the central gear can compensate that from the opposite side and the whole outlet flow fluctuation of the pump is reduced greatly

and the multi-gears pumps with higher-degree elliptical gears are reasonable in application.Furthermore

two circumstances are discussed in detail

three third-degree elliptical gears（called 3-3-3 combination）

and one third-degree elliptical gear and two second-degree elliptical gear（called 2-3-2 combination）.