The compound gear oil pump can greatly reduce the flow pulsation of the gear pump, and has the advantages of large displacement, small volume, high mechanical efficiency, and balanced meshing force. At present, research in this area mainly focuses on:
1) Research on flow characteristics of composite gear oil pump;
2) Research on optimization design method of gear oil pump;
3) Radial force balance methods and measures. There are many parameters involved in the analysis and calculation of the flow characteristics of the compound gear oil pump. The calculation process is complicated and must be realized by means of computer aided design.