| 摘要 |
PURPOSE:To improve the efficiency of pump by making the dimension of diameter of the pitch circle of a high-pressure pump chamber having a labyrinth seal construction smaller than the dimension of diameter of the pitch circle of a low-pressure chamber, and reducing the axial load applied to an impeller in said pump chamber. CONSTITUTION:During the operation of a pump, each pressure on both the low-pressure side and high-pressure side works as a surface pressure load, applying forces which press each other in the axial direction, to the both surfaces of an impeller 5. In order to balance these forces, a pitch circle diameter 18 based on the center of the shaft 9 of a vane part 12 on the high-pressure side is made smaller than a pitch circle diameter 19 based on the center of the shaft 9 of a vane part 11 in a low-pressure chamber. Thus, by reducing a pressure receiving area on the high-pressure side, the forces applied to the impeller 5 on both low-pressure side and the high-pressure side are equalized, reducing axial load applied to the impeller 5 in the pump chamber to improve the efficiency of pump. Furthermore, a labyrinth seal 13 provided on the high-pressure side prevents fuel from leaking from the high-pressure side to the low-pressure side, preventing the lowering of efficiency of pump.
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