| 摘要 |
718,238. Rotary pumps. AKTIEDOLAGET IMO-INDUSTRI. Oct. 23, 1952 [Oct. 25, 1951], No. 26623/52. Class 110(2) A screw pump is provided with a casing consisting of two castings 2, 4 secured to the flange 6 of a housing 8 having intersecting bores in which are arranged a driving screw 10 and idler screws 30, 32, 34. The driving screw has convex thread flanks and the idlers concave thread flanks, the number of idlers and the number of threads on each screw being such that a single tortuous passage is defined through the casing. At one end of the driving screw is a shaft extension 12 rotatably mounted in the casing 2 and at the other end is a shaft extension 14 mounted in a bearing 16. Liquid enters the casing through an inlet 26 and is discharged through an outlet 22. As shown in the drawings, each of the screws has two threads, the idler screws being of opposite hand to the driving screw. The number of idlers n and the number of threads on each screw satisfies the formula G-ng = Π1, where G is the number of threads on the driving screw, and g the number of threads on the idler screws. The length L of the screws and of the housing is preferably not less than N/nP + W, where N is the total number of threads of driving screw and idlers, P is the pitch and W the top width of the driving screw thread. The length of the screw and housing may be at least 8/3 P + W. |
