Francis type split runner

Abstract

Abstract PURPOSE:To provide a Francis type split runner having balancing holes in a cover plate for covering the space around a flange-coupled section, which is designed such that only compressive load is acted to the cover plate while reducing tension load, by specifying the diameter of the balancing hole located radially inwards of the cover plate. CONSTITUTION:A cover plate 7 covers a flange together with ribs or circumferential rings 6 and the outside of the cover plate 7 is in turn surrounded by an upper cover or a lower cover 8. Here, the diameters of balancing holes (a), (b) formed in the cover plate 7 are so selected that the diameter of the balancing hole (a) located radially outwards of the cover plate 7 is more than 1.1 times as great as that of the balancing hole (b) located radially inwards. By employing such an arrangement, relationship between pressure P1 in a back- pressure chamber formed between the cover plate 7 and the cover 8 and pressure P2 inside the cover plate 7 becomes as shown in the drawing. That is, since the tension load acted to the cover plate at its outer circumferential side is reduced as compared with that in the conventional arrangements and compressive load is acted as a whole, it results in that the strength of the cover plate 7 is increased relatively.

Inventors

• 👤 Hiroshi Honma
• 👤 本間　啓

Bibliographic Details