US3042370A - Vane ring assembly - Google Patents

Description

July 3, 1962 H. W. WELSH VANE RING ASSEMBLY Filed Oct. '7, 1957 4 INVENTOR. 50 QiwVgyiZfi BY United States Patent "ice 3,042,370 VANE RING ASSEMBLY Harvey W. Welsh, Indianapolis, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 7, 1957, Ser. No. 688,706 2 Claims. ((11. 253-78) nating annular rows of fixed and moving blades. A ring of fixed blades may be referred to as a stator ring. In 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 structure, 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 the halves 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 shroud and the restraint it places on the deflection of the vanes. It also increases local stresses in the shroud and vanes. Since the vane ring is deflected axially of the compressor by the load put on the vanes by air flow, 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 eflected 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 sections and the coupling pulls these together, the inner shroud and the vanes will be put in tension by the coupling and the outer shroud will receive a compressive load.

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 embodiment of the invention, a structure is shown in which the case and vane rings are in two sections. Three or more Patented July 3, 1962 sections could be provided if desired, but two sections are sufiicient 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 apparent from the succeeding detailed description of the preferred embodiments of the invention and the accompanying drawings thereof.

FIGURE 1 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 FIGURE 1, with parts cut away.

FIGURE 3 is a sectional view taken on the plane indicated by the line 33 in FIGURE 2, and

FIGURE 4 is a sectional view taken on the plane indicated by the line 44 in FIGURE 2.

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

Suitably mounted within the case 10 by means not shown are two semi-cylindrical outer shroud sections 20 of a stator vane ring assembly 22 having a number of vanes 24 fixed thereto and to an inner shroud ring 26. The mounting of the vane ring assembly in the case may be as described in my application Serial Number 677,933, filed August 13, 1957, and issued as Patent No. 3,026,087.

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

Referring now to FIGURES 2 to 4 as well as FIGURE 1, each inner shroud section 27, 27 comprises an outer frusto-conical band 28 and an inner hat-section ring 30, these being spot-welded together at their abutting margins 32, thus forming a hollow box-like chamber 33. The vanes 24 are suitably attached as, for example, by brazing to the outer band 28.

Secured within chamber 33 to each of the radial walls 34 of the hat-section ring 30 at one end of each shroud section or both ends of section 27 are circumferentially extending flanges 36 having converging portions 38 and end or tongue portions 40 extending beyond. the end of the shroud section 27 and adapted to be received within the adjacent inner shroud section 27'.

Suitably connecting the ends 40 and welded thereto is a cross member or plate '42 in the shape of a parallelogram and having an annular opening or hole 44 provided with tapered or inclined walls 46 providing a wedging surface or ramp for a purpose to be presently described. It will be noted that the shroud section split line and the crosspiece 42 are skewed with respect to the axis of the compressor so as to not interfere with the mounting of the blades or vanes 24.

Secured to the other inner shroud 27' is an annular guide member 50 having an opening 52 for slidably receiving a bolt or conical wedge 54. Spot-welded to the bottom wall 51 of the hat-section 30 of shroud section 27 is a nut 56 having threads adapted to cooperate with the threads 60 on the radially movable bolt 54. The bolt 54 is tapered at 62 for cooperation with the ramp or wedging surface 46 provided on the member 42, the bolt 54 and nut 56 together constituting a fastening means.

The operation of this device will be obvious by reference to the figures wherein it will be seen that placing the shroud sections 27 and 27 adjacent each other will telescope the cross-piece 42 within chamber 33 so as to be positioned in alignment with the guide member 50 and the nut '56. Thereafter, insertion of the bolt 54 into the guide 50, cross-piece 42, and nut 56, and tightening of the same in the nut will cause radial movement of the tapered portion 62 of the bolt to engage the cam surface 46 of the hole in cross-piece 42 to cam the section 27 circumferentially into abutting engagement with section 27. 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 bolt 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 coupling for securing the inner shroud sections together to prevent circumferential and axial movement thereof. It will be understood that the invention can be modified beyond the illustrated embodiments, and therefore, any limitations to be imposed are those set forth in the following claims.

I claim:

1, A vane ring assembly comprising a plurality of circumferentially arranged areuate sections together forming a ring-like body, each of said sections comprising an outer shroud, an'inner hollow shroud, and vanes between said shrouds; and means connecting the arcuate sections of said inner shrouds, said means comprising tongues fixed within said hollow member on one of said sections and extending circumferentially therebeyond, the hollow member of an adjacent section telescopically receiving said tongues a part rigidly fixed to said tongues at their ends and having a tapered hole therein extending radially of the ring, mutually coaxial guide means and fastening means on said adjacent section, and a tapered pin progressively movable radially of the ring into and through said guide means and hole into engagement with said fastening means for connecting said sections together, said hole being slightly offset relative to the axis of the guide means and fastening means, said pin having a conical surface for contact with the said part upon radial movement of said pin for circumferentially moving said connecting means and one section towards the other section.

2. An assembly as recited in claim 1 in which the said pin and fastening means are threaded together, rotation of the pin thus moving the pin into the hole.

References Cited in the file of this patent UNITED STATES PATENTS 2,371,801 Chester et al. Mar. 20, 1945 2,428,999 Smith et al. Oct. 14, 1947 2,442,184 Summers May 25, 1948 2,772,069 Hockert et al. a Nov. 27, 1956 2,945,673 Hockert et al. July 19, 1960 FOREIGN PATENTS 77,606 Sweden Jan. 14, 1932

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