PURPOSE: To prevent the occurrence of scuffing between a balance disc and a balance seat by a method wherein a gap is provided between the outer peripheral part of the flange of the balance disc and the balance seat and an inner peripheral part having thickness lower than that of the outer peripheral part of the flange is formed in a position inner than the outer peripheral part of the flange.
CONSTITUTION: A flange 13A forms diaphragm structure wherein the thickness of an inner peripheral part is decreased to a value lower than that of an outer peripheral part, and the inner peripheral part is easily deformed by shaft thrust. A balance seat 14 is fixed to the part, where the flange 13A is positioned facing a delivery casing 4, of a delivery casing 14, and a gaps 16a and 16B are formed between the outer peripheral part, where thickness is increased, of the flange part 13A and a parallel part 13B, and the balance seat 14. When a rotary shaft 7 is inclined, the gap 16a is decreased, a flow rate of leaking fluid is reduced, and fluid in an intermediate chamber 17 is boosted. This constitution causes deformation of the inner peripheral part of the flange part 13A and enlarges a gap. Thus, scuffing between the flange and the balance seat is prevented from occurring.
OKADA AKIHISA
MORINAGA TAKAYUKI
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