Apparatus for tying moving blades

• US 3,990,813 A
• Filed: 11/27/1974
• Issued: 11/09/1976
• Est. Priority Date: 11/30/1973
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ikeuchi, Kazuo, Imai, Tetsu
• Primary Examiner(s): Powell, Jr., Everette A.
• Application Number:
  US05/527,879
• Time in Patent Office: 713 Days
• Field of Search: 416/195, 416/196, 416/190, 416/191
• US Class Current: 416/196.00R
• CPC Class Codes: F01D 5/22 Blade-to-blade connections, e.g. for damping vibrations

Abstract

The annular array of radially extending blades on the rotor of a rotary fluid machine are tied together at generally their mid portions by interlocking separate tying members and projection pairs, wherein each projection pair includes facing projections on adjacent blades of the array. The tying members and projections have mating bearing surfaces that will provide a tangential force as a result of wedging produced by the centrifugal force acting upon the tying members during rotation of the rotor at rated speed, without restraining individual twisting of the blades about their radial extent.

Claims

1. In a rotary fluid machine having a rotor with an annular array of generally radially extending blades with radially inner and outer ends, the improvement being in apparatus for tying the blades together between their inner and outer ends, comprising:

said blades having a plurality of pairs of projections, each pair of projections consisting of a first projection provided on one of said blades and a second projection provided on the adjacent blade in facing relationship with respect to said first projection, each of said first projections having a bearing surface and each of said second projections having a bearing surface facing the bearing surface of said first projection of said pair, and at least part of said bearing surfaces of each pair increasing in tangential distance from each other toward the axis of rotation;

a plurality of tying members separate from said blades and corresponding in number to the number of said pairs of projections, each of said tying members extending between the bearing surfaces of a corresponding pair of projections, each of said tying members having bearing surfaces at their opposite ends of mating shape with the corresponding bearing surfaces of said first and second projections, and each of said tying members being mounted for limited radial movement outwardly with respect to its adjacent blades;

said mating bearing surfaces engaging each other around the entire annular array of said blades during rotation of the rotor to provide wedge means for applying tangential forces between adjacent blades resulting from the centrifugal forces acting upon and radially outwardly moving said tying members to interbrace the blades tangentially around the array at a predetermined speed of the rotary fluid machine and restrain tangential vibrations;

at least the cooperating first projections and adjacent ends of the tying members associated therewith having means positively restraining rotation of the tying member about a line drawn between its opposite bearing surfaces;

said engaging bearing surfaces of said projections and tying members being at least partly arcuate in shape as viewed in a tangential plane passing through them for each pair to provide means for permitting relative axial movement between the adjacent projections of each pair of projections as caused by twisting of each blade about its radial extent;

the bearing surfaces for each of said tying members including spherical portions and at least one planar portion that is perpendicular to the radial direction, and each of said projections having a recess receiving therein said spherical portions and said planar portion of the tying member with substantial clearance at least in the radial direction for said planar portion when the rotor is at rest;

said recesses and planar portions at least in part constituting said means restraining motion.

2. The apparatus of claim 1, wherein said recess and said tying member bearing surfaces have substantial play in a direction parallel to the axis of rotation.

3. The apparatus of claim 2, wherein the bearing surfaces for each of said recesses have spherical portions of substantially the same radius as and for correspondingly engaging in the spherical portions of said tying members.

4. The apparatus of claim 1, wherein the bearing surfaces for each of said recesses have spherical portions of substantially the same radius as and for correspondingly engaging the spherical portions of said tying members.

5. The apparatus of claim 1, wherein each of said recesses includes a planar portion that is perpendicular to the radial direction and facing the adjacent tying member planar portion with a substantial radial space therebetween when the rotor is at rest, and the adjacent planar portions of said recesses and tying members being in frictional contact at the predetermined speed to dampen, tangential vibration of the moving blades when the rotor is at the predetermined speed.