US 3070353 A
Description (OCR text may contain errors)
Dec 25, 1962 H. w. WELSH 3,070,353
SHROUD ASSEMBLY Filed Dec. 3, 1958 2 Sheets-Sheet 1 [J INVENTOR! A T'TOHNE Y Dec. 25, 1962 H. w. WELSH 3,070,353
SHROUD ASSEMBLY Filed Dec. 3, 195a 2 Sheets-Sheet 2' IN VEN TOR.
Patented Dec. 25, 1962 3,070,353 SHROUD ASSEMBLY Harvey W. Welsh, Indianapolis, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Dec. 3, 1958, Ser. No. 777,992 4 Claims. (Cl. 25378) This invention relates to compressor and turbine constructions.
More specifically, this invention relates to the construction of a stator vane assembly for either a turbine or compressor of a gas turbine engine with particular attention being directed to the shroud ring for supporting both the stator vanes and rotor blade abradable shroud rings.
This invention further relates to a shroud assembly constructed in a manner to be quickly and easily fitted within the compressor or turbine casing. This invention accomplishes this objective by providing a shroud ring with upstanding flanges having axial and radial crimped portions circumferentially alternated thereon abutting depending axially spaced annular ridges secured to the compressor or turbine casing, thus both axially and radially locating the shroud ring with respect to the casing.
Therefore, it is an object of this invention to provide a shroud ring of the type described with radial and axial crimped or crinkled portions cooperating with the turbomachine casing for axially and radially locating the shroud.
' Other features, advantages and objects will become apparent by reference to the detailed description of the invention and to the drawings wherein there is shown the preferred embodiments of this invention.
In the drawings:
FIGURE 1 is a cross-sectional view of a portion of an engine casing together with the shroud rings embodying this invention,
FIGURE 2 is a perspective view of portions of two adjacent shroud rings,
FIGURE 3 is an enlarged view of a detail of FIGURE 1, and
FIGURE 4 is an enlarged cross-sectional view of a portion of the shroud ring assembly of FIGURE 2.
Referring now more particularly to the figures, there is shown therein a casing of a gas turbine engine, which in this case may be either a compress or turbine casing enclosing the respective compressor or turbine. Formed as a part of the engine casing 10 are a number of axially spaced annular bosses or pads 12 having depending flanges or ridges 14 extending internally of the casing.
Secured to the engine casing between adjacent flanges or ridges 14 by means to be described is a combined stator vane and rotor blade shroud ring assembly 16 forming the subject of this invention.
Each assembly 16 comprises a plurality of circumferentially spaced stator vanes 18 secured by welding or other suitable means to an inner shroud ring 20 and an outer shroud ring 22. The inner shroud ring 20 is formed as shown in an annular zigzag or labyrinth manner to provide for thermal expansion and sealing. The outer shroud 22 to which this invention is primarily directed includes an annular sheet metal plate 24 stepped or rolled at one portion 26 to provide a recess 28 for the insertion therein and securing thereto of an abradable ring 30 constituting the rotor blade shroud ring. The plate 24 is beaded at 32 for a purpose to be described and is bent at both edges to form radial outwardly extending flanges 34 and 36.
Secured to both the flat portion and radial flange of plate 24 is a second annular sheet metal plate 38 flanged and rolled at 40 and 42, respectively, and spot-welded to the plate 24 and flange 36 as shown to form a hollow box section 44 for supporting the stator vanes 18. Suitable apertures 46 equally spaced circumferentially around each of the plates 24 and 38 are provided therein for the insertion therethrough and welding thereto of the stator vanes 18, the apertures 46 in the two plates being radially aligned and equal in number. Thus the stator vanes are securely held against axial and radial movement with respect to the shroud, and are located with respect to the rotor blades.
The radial flanges 34 and 36 are each crimped or ruflied at their outermost radial portions or edges as shown more clearly in FIGS. 2 and 3 to provide an axial flange portion 48 alternating with a radial flange portion 50, the two radial and axial portions being circumferentially alternated around the entire annulus. The axial and radial flanges 48 and 50 are thus adapted to abut the radial and axial surfaces 52 and 54 provided on the ridges 14 and pads 12, respectively, formed on the casing 10. Thus, an axial and radial locating surface is provided for axially and radially locating the stator vane and rotor blade shroud ring with respect to the rotor blades 55 and casing 10. As shown, the alternate radially and axially crimped portions of each of the flanges 34 and 36 face outwardly,
with the axial distance therebetween defining the axial width of the shroud section corresponding to the axial distance between the ridges 14. As seen in FIGURE 3, the shroud plate 24, as mentioned previously, is rolled at 32 so as to underlie the ridge 14 and extend to a point closely adjacent the abradable rotor blade shroud 30 therefore acting as a gas seal to restrict communication of the hot motive fluid to the engine case 10. Thus, it will be seen that opposite edges of the shroud sections abut opposite face portions of the ridges 14.
While the shroud rings have been referred to as annular, by referring to FIGURE 4, it will be seen that these shroud rings are composed of two segments having radially outwardly directed flanges 60 formed at each end thereof for insertion into recesses 62 in the engine casing. Centrally of each shroud section, a threaded Pin 64 is welded thereto to plate 38 between the blade members andv extended through a suitable aperture 66 in the engine casing to be secured thereto by a nut 68. The engine casing is also formed in two 180 segments with flanged portions 70 at their abutting edges joined together by nut and bolt means 72, the nut and bolt means also securing the two flanged portions 60 of the shroud rings together.
To assemble the shroud ring of this invention, the an nular sheet metal ring 24 is bent and rolled as shown to provide the two radial flanges 34 and 36, the recess for the abradable rotor blade shroud and the axially extending portion 32. The outer portions of the flanges 34 and 36 are then crimped as shown to provide circumferentially alternated axial and radial flanges 48 and 50. The sheet metal plate 38 is then formed as shown and secured to the plate 24. Slots are then cut in both the plates 24 and 38, the abradable surface 30 is secured thereto, and the vanes 18 are inserted through the slots and secured to the plates. The shroud ring assembly now being complete, the radial and axial locating surfaces are then machined to fit the particular compressor case cooperating with the ridges 14 and pads 12. The shroud ring assembly is then inserted in one half of the engine case with the flanges 48 and 50 abutting the radial and axial portions of ridges 14 and pads 12 thus radially and axially locating the shroud ring with respect to the casing and rotor blades 55. The shroud ring is then secured to the engine casing by the nut 68 as seen in FIGURE 4. The other half of the engine case is assembled in the same manner, and the two segments are then positioned over the rotor of the turbine or compressor, whichever the case may be, and secured together by the nut and bolt means 72.
While the shroud ring has been defined as extending axially to provide-for a rotor -blade shroud, -it willbe clear that this could be used just as a stator vane shroud without departing from the scope of the invention.
Thus, it will be seen that the crimped or deformed edges 48 and 50 provide a machiningsurface that can bemachined accurately and easily to conform to the axial width between ridges 14 and the interior case diameter, therefore permitting easy and accurate assembly of the shroud ring to the casing. Thus, the shroud can be machtned to fita particular installation and accommodates for any case distortion during manufacture.
From the foregoing it will be seen that thisinvention having internal mutually adjacent axially and radially facing locating surfaces; a relatively thin sheet metal shroud ring within said case having a locating surface contacting edge extending radially outwardly into contact with said case locating surfacesgthe outer periphery of said contacting edge being annular and defined by circumferentially alternated radially and axially extending bent por' tons contacting respectively the radially and axially facing locating surfaces on said case to radially and axially locate said shroud ring with respect to said case.
2. A turbomachine shroud ring locating assembly comprising, in combination, an annular turbomachine case.
having axially spaced ridges depending internally from said case, said ridges having opposite axial sides each side having mutually adjacent axially and radially facing loeating surfaces, a plurality of relatively thin sheet metal shroud rings within said case each having a locating surface contacting flange extending radially outwardly from a opposite axial edges of said ring each into contact with a set of said case locating surfaces, the outer periphery of each of said contacting flanges being annular and defined by circumferentially alternated radially and axially extending bent portions contacting respectively the radially .1
and axially, facing locating surfaces on said case'with which the portions are associated to radially and axially locate said shroud ring with respect to said case, the
shroud rings being axially adjacent each other to provide spaced sets of mutually adjacent contacting flanges, the 1 different flanges of each set of flanges being aligned with 5 and contacting different sides of the same case ridge.
3. A turbomachine shroud ring locating assembly com.- prising, incombination, an annular turbomachine case having axially spaced ridges depending internally from said case, said. ridges having opposite axial sides. each side having mutually adjacent axially and radially facing locating surfaces, a plurality of relatively thin sheet metal shroud rings Within said case each having a locating surface contacting fiange extending radially outwardly from opposite axial edges of said ring each into contact with a set of said case locating surfaces, the outer periphery of each of said contacting flanges being annular and defined by circumferentially alternated radially and axially extending bent portions contacting respectively the radially and axially facing locating surfaces on said case with which theportions are associated to radially and axially locate said shroud ring with respect to said case, the shroud ringsbeingaxially adjacent each other to provide spaced setsof mutually adjacent contacting flanges, and means formed on one 0f the flanges of one of said sets cooperating with the adjacent flange of the set to form a fluid sealtherebetween 'to restrict communication of fluid radially outwardly from said rings to said case.
4. A turbomachine shroud ring locating assembly comprising,,in combination, an annular turbomachine case having internal mutually adjacent axially and radially ffiC',
ing locating surfaces, a relatively thin sheet metal shroud ring within said case having a locating surface contacting edge extending radially outwardly into contact with said case locating surfaces; the outer periphery of said contacting edge beingannular and defined by circumferentially alternated radially and axially, extending bent portions' contacting respectively theradially and axially fac- 1 ing locating surfaces on said case to radially and axially locate said shroud ring with respect to said case, a plurality of circumferentially spaced stator vanes secured to said shroud fring, said shroud ring including axially extending means secured thereto and having a portion spaced therefrom together with said ring forming a tubular stator vane supporting structure having radially inner and outer separated walls, said walls having apertures therein constituting guide means upon the insertion of said stator vanes therein andtherethrough to axially locate said vanes with respect to said shroud ring.
References Cited in the file of this patent UNITED STATES PATENTS 2,488,867: Judson Nov. 22, .1949" 2,507,079 Zimmerman May 9, 1950 2,658,719. Johanson Nov. 10, 1953 2,749,026 Hasbrouck et al June 5, 1956 2,766,963 Zimmerman. Oct. 16, 1956 2,771,622 Thorp Nov. 27, 1956 2,910,269 Haworthuetal. Oct. 27, 1959 FOREIGN PATENTS 975,879 France Oct. 17, 1950 1,057,993- France- Nov, 4, 1953 789,733 Great, Britain Jan. 29, 1958