Abstract: The suction flow resistance rises in the electric motor-pump due to the flow of cooling oil through the suction channel to take away the heat, which affects the sufficiency of oil suction. To solve this problem, a port-plate centrifugal pump is placed in front of the main pump. The experiment of the electric motor-pump and the electric-hydraulic power unit with equal power is done and the flow field simulation of suction channel for different rotational speed is calculated, the influence rule of rotational speed on main pump suction flow field is obtained. The research results show that the suction performance of the main pump is evidently improved by the port-plate centrifugal pump and the maximum value of the total pressure on the outlet port of the port-plate centrifugal pump (the inlet port of the main pump) almost increases linearly with the increase of rotational speed. The volumetric efficiency of the electric motor-pump is nearly 1.25% higher than that of the electric-hydraulic power unit. When the rotational speed is below 1 395 r/min, the port-plate centrifugal pump causes an adverse impact on the suction performance of the main pump. The volumetric efficiency relatively decreases by 2.7% with the delivery pressure rising to 22 MPa. The exact meaning of charging effect is summarized.

Key words: electric motor-pump;port-plate centrifugal pump;charging effect;flow field simulation;experiment