US3070352A

US3070352A - Vane ring assembly

Info

Publication number: US3070352A
Application number: US694776A
Authority: US
Inventors: Harvey W Welsh
Original assignee: General Motors Corp
Current assignee: Motors Liquidation Co
Priority date: 1957-11-06
Filing date: 1957-11-06
Publication date: 1962-12-25
Anticipated expiration: 1979-12-25
Also published as: GB841815A

Description

Dec. 25, 1962 H. w. WELSH 3,010,352

VANE RING ASSEMBLY Filed Nov. 6. 195'? IN VEN T 0R.

' stator ring.

. Valles.

United States Patent O 3,070,352 VANE RING ASSEMBLY Harvey W. Welsh, Indianapolis, Ind., assignor to General My invention relates to stator vane ring assemblies for axial-flow turbomachines and, more generally, to such axialilow machines. It is particularly adapted to the requirements of axial-flow compressors such as are employed in aircraft gas turbines, but is not limited thereto.

By way of explanation and background, it is well known that most axial-flow compressors and turbines have alternating annular rows of fixed and moving blades. A ring of fixed blades may be referred to as a ln most cases, the stator ring comprises an outer shroud, an inner shroud, and vanes extending radially between and fixed to the shrouds. The outer shroud is fixed to the compressor case and the inner shroud ordinarily provides or supports a labyrinth seal acting against the rotor. In order to assemble the compressor, that is, to mount the rotor in the stator stnucture, the compressor case ordinarily is split along a plane containing the axis of the compressor into two segments, or halves, which are fixed together at what -is called the split line on each side of the case. The stator vane rings likewise are made in 180 degree sectors, or halves. The stator vane ring halves are fixed to thehalves of the compressor case. After the rotor has been mounted in one half of the case, the other half is placed over the rotor and the two halves of the case are bolted together or otherwise joined at the split lines.

One purpose of the inner shroud is to increase the strength and stiffness of the stator vane structure. However, the usual practice of dividing the inner shroud into two sections greatly reduces the strength of the inner v shroud and the restraint it places on the deflection of the vanes. It also increases local stresses in the shroud and Since'the vane ring is deflected axially of the compressor by the load put on the vanes by airflow, a rigid structure which minimizes this deflection is highly desirable because'it makes it possible to reduce stage clearances in the compressor and reduce distortion of the seal between the inner shroud and the rotor.

My invention substantially eliminates the defects of the previous split vane ring assemblies by providing a strong mechanical attachment between the adjoining ends of the sections of the inner shroud so that the inner shroud becomes a mechanical equivalent of a continuous ring. This is effected by a coupling device which may be readily applied to fasten the two halves of the inner shroud together. Preferably, although not necessarily, the attachment is such as to put the inner shroud rings in tension. Thus, if a small clearance is provided between the shroud sect-ions `and the coupling pulls'these together, the inner shroud and the vances will be put in tension by the coupling and the outer shroud will receive a compressive load. j

By this means, a vane assembly is provided which may be taken apart for assembly and disassembly of the compressor but which has mechanical strength substantially equivalent to a continuous 360 degree vane assembly. The rigidity of the structure is high, and distortions with the undesirable effects referred to above are minimized.

A further advantage of a structure according to the invention and a further feature of the invention is that the rigid fixing together of the halves of the vane ring assembly makes it unnecessary to provide a rigid attachment between the outer shroud and the case.

In the succeeding description of the preferred embodi- ICC ments of the invention, a structure is shown in which the case and vane rings are in two sections. Three 0r more sections could be provided if desired, but two sections are sufficient to provide for assembly of the compressor. For conciseness, the term shroud or ring will be applied to the arcuate sections thereof as well as to the assembled 360 degree shroud or ring.

The nature of the invention and the advantages thereof will be more clearly 4apparent from the succeeding detailed description of the preferred embodiments of the invention and the accompanying drawings thereof.

FIGURE l is a partial transverse sectional view of a stator vane assembly,

FIGURE 2 is a fragmentary view of a shroud coupling taken on the plane indicated by the line 2--2 in FIG- URE 1, with parts cut away,

FIGURE 3 is a sectional View taken on the plane indicated by the line 3-3 in FIGURE 2,

FIGURE 4 is a sectional view taken on the plane indicated by the line 4-4 in FIGURE 2, and

FIGURE 5 is a perspective view of a detail.

Referring now to the drawings and more particularly to FiGURE 1, there is shown therein a compressor case 10 consisting of two semi-cylindrical sect-ions or halves 12 and 14 having flanges -16 formed at their edges and joined together by suitable bolts 18.

Suitably secured to the case 10, by means not shown, are a number of semi-cylindrical outer shroud sections 20 of a stator vane ring 22 hav-ing a number of vanes 24 fixed thereto and to an inner shroud ring 26 made up of two sections 27.

The manner in which the inner shroud sections are connected together is the subject of this invention.

Referring now to FIGURES 2 to 5 as well as FIGURE 1, each inner shroud section 27 comprises an outer frustoconical band 28 and an inner hat-section ring '30, these being spotwelded together at their abutting margins 32l to form a hollow box-like chamber 33. The vanes 24 are suitably attached as, for example, by brazing, to the band 28.

Secured to the radial walls 34 within the box-like chainber 33 of one end of each shroud section 27 is a thin plate -40 having a semi-circular end 41 extending beyond the end of section 27 and adapted to be receivedwithin the end of the other shroud section 27. Suitably provided within the end portion 41 of plate 4t) is a slot 50 with rounded edges adapted to receive a camming lug 52 eccentrically mounted on an annular pin or plug 54. The lug 52 is formed at its end with an enlarged annular portion 56 of a diameter slightly less than the width of the slot 50 and adapted to engage one side 58 of the plate 40, with the abutting port-ions 60 of the plug S4 engaging the opposite side 62 of the plate 40 to prevent radial movement of the plug with respect to the plate. The plug 54 is rotatably mounted on the adjacent end of the other shroud section 27 within a hollow annular guide member or boss 64 secured as by welding to the underside of' the outer band 28 of shroud section 27. The plug 54 has a slot 68 extend-ing across the top face thereof for a suitable tool to rotate the plug. Also secured to the outer band 28 of shroud 27 is a flexible finger-like locking means 70 having a tab portion 72 adapted to engage in the slot 68 of plug 54 to prevent rotation of the same.

The operation of this shroud coupling will be clear by referring to the drawings wherein it will be seen that initially, the two shroud sections 27 will be brought together so that the end portion 41 of each plate 40 is telescopcally received within the hollow box chamber of the adjacent shroud section with the slot 50 in alignment with the hole 63 in guide 64. Thereafter, upon raising the flexible finger 70 in the manner as seen in dotted lines in FIGURE 4, the plug 54 is inserted in the guide 64 and the portion 56 through slot 50. A suitable tool (not shown) is inserted in the Slot 63 to rotate the pin. Rotation of the pin or plug will cause the eccentric 52 to bear against the walls of the slot or aperture 50 of plate 40 exerting a circumferential force t0 cam the shroud sections into abutting relationship. Thereafter, the locking means 70 is bent downwardly to engage in the slot 63 of plug 54 to prevent further rotation of the eccentric in either direction, thereby securely connecting the two shroud sections 27 together. A very strong and rigid attachment between the stator rings is thus provided and the inner shroud is put in tension.

As will be apparent, both of the couplings at the two split lines may be identical. The slot 68 in plug 54 may be reached by a suitable tool to tighten or release the coupling through the clearances between the stages or through a hole (not shown) in the outer shroud before the top half of the case is assembled onto the lower half.

From the foregoing it will be seen that this invention provides a rigid, simple, and light-weight coupling for securing the inner shroud sections together to prevent circumferential and axial movement thereof.

It will be understood that the invention can be moditied beyond the illustrated embodiments, and therefore, any limitations to be imposed are those set forth in the following claims.

I claim:

1. A vaned ring assembly including a plurality of relatively movable arcuate sections to be joined, each of said sections having an outer shroud, an inner shroud, and vanes connected between said shrouds, and means on said inner shrouds for securing said sections together, said means including flange means secured to one of said sections and extending circumferentially into adjacency with another of said sections, said ange means having an aperture therein, and securing means rotatably mounted on said other section and extending radially through said aperture with a loose t, said securing means being eccentrically mounted with respect to the axis about which it rotates, rotation of said securing means in one direction engaging said securing means with the walls of the aperture in said flange means to move said flange means circumferentially and said sections together and placing said sections in tension by causing relative movement of said sections until adjacent ends abut each other.

2. A vaned ring assembly including, a plurality of arcuate sections to be joined, each of said sections having an outer shroud, an inner shroud, and vanes connected between said shrouds, and means on said inner shrouds for securing said sections together, said means including hollow boss means secured to one of said sections, rotatable means extending radially through said boss means, and connecting means secured to another of said sections operatively connecting said rotatable means and another of said sections, said connecting means having an opening at one end thereof, a cam eccentrically mounted 0n said rotatable means with respect to the radial axis of said rotatable means and extending loosely through said opening, rotation of said rotatable means engaging said cam with the walls of said opening in said connecting means for moving said connecting means and camming said sections together placing said inner shroud sections in tension.

3. A vaned ring assembly including, a plurality 0f circumferentially arranged arcuate sections to be joined, each of said sections having an outer shroud, an inner shroud, and vanes connected between said shrouds, and means on said inner shrouds for securing said sections together, said means including plate means extending circumferentially between said sections and secured to` one of said sections at one of its ends, said plate means having an aperture at its other end, guide means secured to another of said sections, and rotatable connecting means positioned within said guide means and said aperture for connecting said sections together, said rotatable means having a cam eccentrically mounted thereon for movement about a radial axis, said cam being positioned within said aperture, rotation of said rotatable means causing said cam to bear against said plate means to move said sections circumferentially relative to each other for alternately tightening or loosening the connection between the two.

References Cited in the le of this patent UNITED STATES PATENTS 728,093 Ellingson May 12, 1903 1,796,748 Coquille Mar. 17, 1931 2,205,474 Goeller June 25, 1940 2,371,801 Chester et al. Mar. 20, 1945 2,442,184 Summers May 25, 1948 2,722,069 Hockert et al. -..v Nov. 27, 1956 2,945,673 Hockert et al. July 19, 1960 FOREIGN PATENTS 730,955 France May 25, 1932 621,544 Great Britain Apr. 1l, 1949