| 摘要 |
A pump casing for centrifugal pumps which can be obtained by casting, pressure die-casting or by means of another process for forming a metallic material, comprises an axial suction inlet (3; 3') connected to a pressure chamber (5; 5') shaped as an annular volute. A centrifugal impeller (6; 6') is arranged in the pressure chamber which is provided with a radial discharge outlet (4; 4'). The suction inlet (3; 3') has a substantially radial peripheral passage (9; 9') and an axial channel (18; 18'), at the region where it blends with the pressure chamber (5; 5'). The peripheral passage and the axial channel are connected to the pressure chamber and are obtained by means of a single core (F) which forms both the suction inlet and the pressure chamber. An annular ridge (19, 19') is formed along the edge of the axial opening (18) and forms an axial skimming surface (20; 20') for the non-bladed part of the impeller (6). Together with the impeller the ridge forms an element for separating the suction inlet (3) from the pressure chamber (5). The annular ridge (19') is interrupted by a radial groove (25) to avoid sticking and reduce friction during pickup. |
