US2722373A

US2722373A - Compressor casing and stator assembly

Info

Publication number: US2722373A
Application number: US209556A
Authority: US
Inventors: Walter A Ledwith; Jr Edgar C Shoup
Original assignee: United Aircraft Corp
Current assignee: Raytheon Technologies Corp
Priority date: 1951-02-06
Filing date: 1951-02-06
Publication date: 1955-11-01
Anticipated expiration: 1972-11-01

Description

2 sheets-5119"c 1 W. A. LEDWITH ETAL COMPRESSOR CASING AND STATOR ASSEMBLY Filed Feb. 6 1951 NOV- 1, 1955 w. A. LEDWITH :TAL 2,722,373

COMPRESSOR CASING AND STATOR ASSEMBLY Filed Feb. 6, 1951 2 Sheets-Sheet 2 IIIlIllllIIlIl/lllll I' ,.lllfll "funn Y quill /e g@ L Q United States Patent O COMPRESSOR CASING AND sTAToR ASSEMBLY Walter A. Ledwith, Glastonbury, and Edgar C. Shoup, Jr., West Hartford, Conn., assignors to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application February 6, 1951, Serial No. 209,556

9 Claims. (Cl. 230-133) This invention relates to a compressor and particularly to the arrangement of the casing and the stator vanes carried by the casing in a multistage axial flow compressor.

Where weight is a serious problem, as in aircraft power plants, an annular casing with no longitudinal splits provides a lighter construction with the rows of stator vanes being assembled by insertion axially into the casing. A feature of this invention is an annular casing within which the rows of stator vanes may be positioned, with the rows of vanes being split and the casing serving to hold the rows of vanes in assembled relation. Another feature is the interposition of spacer rings between adjacent rows of stator vanes for maintaining the spacing between the vanes and for locking the rows of vanes against rotation within the casing. Another feature is the arrangement of the casing such that its inner surface diminishes in diameter from one end to the other to facilitate the positioning of the casing over the assembled stator vanes and spacer rings.

One feature of the invention is an arrangement by which to secure the several rows of stator vanes against rotation Within the casing Without the necessity for a securing means between the casing and each separate row of vanes. Another feature is the attachment of one of a group of rows of vanes to the casing and the provision of intenengaging lugs on the other rows of the group to prevent relative rotation.

Other objects and advantages will be apparent from the specilication and claims, and from the accompanying drawings which illustrate an embodiment of the invention.

Fig. l is a side elevation partly in section of the compressor casing.

Fig. 2 is a fragmentary sectional View on a larger scale of the section delineated by the dotted lines of Fig. l.

Fig. 3 is a fragmentary sectional view substantially on line 3 3 of Fig. 2.

Fig. 4 is a fragmentary developed View substantially on line 4-4 of Fig. 2.

Fig. 5 is a fragmentary longitudinal sectional view of a modification.

The invention is shown in a multistage axial flow compressor construction in which the casing 2 is unsplit in a longitudinal direction such that there is no need for bolting tlanges or the like thereby reducing the weight of this element. This construction also permits the contours of the casing to be produced by turning operations, to give accurate control of wall thickness. The casing may be made up of a number of separate circumferentially continuous rings 2a and 2b, in which event the adjacent edges of the rings may have complementary langes 4 and 6 (Fig. 2) by which the casing rings may be held together as by bolts 8. For piloting the adjacent casing rings it may be advantageous to have one of the ilanges (flange 6 in the arrangement shown) provided with a cylindrical flange 10 at its periphery of such a dimension as to receive and t closely around the peripheral surface of the 2 cooperating flange 4, thus piloting the ring 2a with respect to ring 2b.

The casing preferably decreases in diameter from one end to the other and the inner surface may be provided with a number of axially spaced piloting surfaces 12 each of which is preferably smaller in diameter than the adjacent piloting surface for ease of assembly as will hereinafter appear. As best shown in Fig. 2, the piloting surfaces 12 are substantially cylindrical and they are joined` by sections having frusto-conical inner surfaces.

The casing supports spaced rows 14 of'stator vanes which when the compressor is completely assembled alternate with cooperating rows vof moving blades, not shown. The individual vanes making up any one of the rows of vanes 14 are supported at their outer ends by a shroud ring 16 which may be axially tapered or frustoconical and which, in the arrangement shown, is provided with openings 18 to receive the individual shroud piece 20 on each individual vane. The shroud pieces may be welded or brazed or otherwiser positively held in the shroud ring 16. The inner ends of the vanes may be secured in position as by an inner shroud ring 22, Fig.V l.

For the purpose of maintaining the proper spacing between adjacent vane shrouds, spacer rings 26 are positioned between adjacent shroud rings and are preferably notched to form radially extending lugs at opposite edges as at 28 and 30 to cooperate with similar notches 32 and 34 in the edges of the shroud rings. The spacer rings 26 and the adjacent shroud rings preferably have integral inter-engaging means in the form of interlocking detents 36, Fig. 4, which serve to prevent relative rotation between the spacer rings and the adjacent shroud rings. It will be noted that the spacer rings have piloting surfaces 38 which may be on the detents 36 and which engage the surfaces 12 to position the spacers accurately within the casing. The surfaces 38 are preferably located adjacent to the edges of the spacer ring.

For the purpose of preventing rotation of the rows of vanes within the casing, one of the centrally located spacer rings out of a group of interlocked spacer rings and shroud rings has /a radially extending ilange 42 which is positioned between the flanges 4 and 6 of the casing and is prevented from rotation with respect to the casing by the same bolts 8 that hold the casing rings together. The flange 42 is preferably located on the endmost ring of the group such 'that the clamping of the ilange serves to hold the rings axially in position within the casing. Pilot surface 38 on the flange end of this spacer ring is shown as located on the periphery of ilange 42.

For ease of assembly of the casing and stator vane assemblies around the compressor rotor it is desirable to have the shroud rings for the stator vanes split as shown so that the stator vanes may be positioned between adjacent rows of blades on a completely assembled rotor. Thus, in assembling the device, each of the stator rings in the form of 2 halves is assembled around the rotor with the spacer rings appropriately positioned between adjacent shroud rings until at least one group, as abovel described, of inter-engaging spacer and shroud rings are assembled as, for example, the iirst three rows of stator vanes 14a, 14b, and 14o` and the

inter-engaging spacer rings

26a, 26h, and 26a. When these are in position around the rotor it will be apparent that the casing ring 2a may then be positioned around the assembled structure by movement from right to left in Fig. 1 until the radially projecting flange 42a on the spacer ring 26a is engaged with the radial ilange 6a on the casing ring. It will be apparent that the spaced piloting surfaces 12 on the casing ring engage the appropriate piloting surfaces 38 on the spacer rings. In a similar manner the shroud rings and spacer rings enclosed within the casing ring 2b may be assembled around the rotor and then the casing ring may be positioned in a manner similar to that above described in connection with the casing ring 2a; final result is a very light weight casing and stator vane assembly which is suiiiciently strong to withstand the loads applied to itand which also permits the rows of vanes to be split Without a correspondingsplit in the supporting casing. The splits in adjacent vane rings may be staggered circumferentially to eliminate any general plane of flexibility in the assembled structure. It may be further noted that no fastening means are provided between the casing and each individual shroud ring or space r ring since the inter-engaging lugs between adjacent shroud ringsV and spacer rings will function to prevent rotation of the parts within the casing.

In the modification of Fig. 5' the interlockingdetents which align the spacersand shroud rings may be replaced by axial pins 44 which are received in bores 46 in the spacer 26 and other bores 48 in the shroud ring 16. It will be obvious that these pins will transmit the torque between adjacent shroud rings and will also serve to pilot the shroud rings and spacers so that a group of Shroud rings and spacers may be assembled without any extraneous supporting means prior to the positioning of the surrounding casing. Also in this modification, as in the. arrangement of Figs. 1 4, a clearance surface is provided between the piloting surface 12 on the casing andthe shroud ring 16such thatthe spacer ringsare the piloting elements between the outer casing and the shroudl rings.

It is to be understood'that the invention is not limited to the specic embodiment herein illustrated and described, but may be usedin other ways without departure from its spirit as defined by the following claims.

We claim:

l. In a compressor construction, an annular casing the inner surface of which decreases in diameter from one end to the other, axially spaced rows of vanes positioned within the casing, each row of vaneshaving a shroud ring engaging with and supporting the outer ends of a number of the vanes in the row, and spacer rings between axially adjacent shroud rings to maintain the required axial spacing between the rows of vanes, said spacer rings having piloting means thereon for engagement with the inner surfaces of the casing to maintain the concentricity of the spacer rings with respect to the casing, and said shroud rings and said spacer rings having interengaging piloting means to maintain concentricity between the spacer and shroud rings, a group of said spacer rings and shroud rings having inter-engaging means thereon by which to prevent relative rotation, and one of'the centrally located rings of said group having a radially, extending tiange engaging with atlange of said casing and held against rotation relative thereto.

2. In a compressor construction, an annular casing the inner surface of which decreases in diameter from one end to the other, one end of'the casing having a radially extending attaching flange, axially spaced rows of vanes positioned within the casingLeach row having a, shroud ring engaging with and supporting the outer ends, of, a number of the vanes in the row, and spacer rings between axially adjacent shroud rings to maintain the required axial spacing between the rows of vanes, one of said spacer rings having a radially extending ange projecting over and secured to the attaching flangeon thecasing such that the spacer ring is located axially within the casing and prevented from turning therein.

3. In a compressor construction, an annular casing the inner surface of which decreases in diameter from one end to the other, one end of the casing having a radially ex tending attaching flange, axially spaced rows ofvanes positioned within thecasing, each row havingl a shroud ring engaging with and supporting the outer ends of a num,n ber of the vanes in the row, and spacer rings between axially adjacent shroud rings to maintain the required axial spacing between the rows of vanes, one of said spacerr rings having aradially extending flange projecting Theover and secured to the attaching flange on the casing suchthatl thev spacer ringl is located axially within the casing and prevented from turning therein, said spacer ring and a group of shroud rings and spacer rings adjacent thereto having inter-engaging means thereon by which to prevent relative rotation.

4. In a compressor construction, an annular circumferentially continuous casing the inner surface of which. decreases in diameter from one end to the other, axially spaced rows of vanes positioned within the casing, each row having a shroud ring engaging with and supporting the outer ends of a number ofthe vanes of the row, said shroud ring being split longitudinally, and spacer rings between axially adjacent shroud` rings to` maintain the required axial spacing between the rows of vanes, said spacer rings being circumferentially continuous and having piloting means thereon for engagement with the inner surface of the casing to maintain the concentricity of the spacer rings and the adjacent shroud rings with respect to the casing, said spacer rings and the adjacent shroud rings having inter-engaging notches by which to maintain the adjacent rings in concentricity with each other.

5'. In a compressor construction, a casing having a number of concentric spaced surfaces on the inside thereof, axially spaced rows of vanes within said` compressor, each row of vanes having a supporting shroud ring to which the outer ends of the vanes of the row are rigidly secured, and spacers between the shroud rings of axially adjacent rows of vanes, said spacers having means thereonV for engagement with the concentric surfaces on the casing for piloting the spacers and the shroud rings within the casing, said spacers and said shroud rings having inter-engaging detents to prevent relative rotation.

6. In a compressor construction, a casing having a number of concentric spaced surfaces on the inside thereof and also having a radial surface thereon, axially spaced rows of vanes within said compressor, each row of vanes having a supporting shroud ring to which the outer ends of the vanespof the row are rigidly secured, and spacers between the shroud rings of axially adjacent rows of vanes, said spacers having means thereon for engagement with the concentric surfaces on the casing for piloting the spacers and the shrouds within the casing, said spacers and saidshroud rings having interengaging detents to prevent relative rotation, one of said spacers having a radially extending ange engaging with the radial surface on, and attached to, the casing.

7. In a compressor construction, an annular casing` having a plurality of axially spaced cylindrical inner surfaces, with each succeeding cylindrical inner surface of less diameter than the previous cylindrical inner surface and further having sections of frusto-conical inner surface joining adjacent cylindrical inner surfaces, axially spaced rows of vanes positioned within the casing, each row of` vanes having a frusto-conical shroud ring engaging with and supporting the outer ends of a number of the vanes in the row, spacer rings located between axially adjacent shroud rings to maintain the required axial spacing between the rows of vanes such that each shroud ring is positioned within one of said frusta-conical inner surfaces of said casing, each of said shroud rings being of less outer diameter than the inner diameter of said frustoconical inner surface within which it ispositioned so that a substantial clearance exists therebetween, said` spacer rings having piloting means at each end for engagement with the cylindrical inner surfaces of the casing to maintain the concentricity of the spacer rings with respect to the casing, means connecting said shroud rings and said spacer rings to maintain concentricity and to transmit torque and to prevent relative rotation between the` spacer and shroud` rings, and interlocking means joining said spacers and shroud rings with saidcasing to prevent relative rotation therebetween.

8. In a compressor construction, an, annular circumferentially continuous casinghavinga pluralityfof. axially spaced cylindrical inner surfaces with each succeeding cylindrical inner surface of less diameter than the previous cylindrical inner surface and further having sections of frusto-conical inner surface joining adjacent cylindrical inner surfaces, axially spaced rows of vanes positioned within the casing, each row having afrusto-conical shroud ring engaging with and supporting the outer ends of the vanes of the row, said shroud ring being split substantially diametrically, and spacer rings between axially adjacent shroud rings to maintain the required axial spacing between the rows of vanes such that each shroud ring is positioned within one of said frusto-conical inner surfaces of said casing, each of said shroud rings being of less outer diameter than the inner diameter of said frustoconical inner surface within which it is positioned so that a substantial clearance exists therebetween, said spacer rings being circumferentially continuous and having piloting means for engagement with the inner cylindrical surfaces of the casing to maintain the concentricity of the spacer rings and means interlocking said spacer rings with said shroud rings to prevent relative rotation therebetween and to maintain concentricity therebetween.

9. In a compressor construction, an annular circumferentially continuous casing having a plurality of axially spaced cylindrical inner surfaces with each succeeding cylindrical inner surface of less diameter than the previous cylindrical inner surface and further having sections of frusto-conical inner surface joining adjacent cylindrical inner surfaces, axially spaced rows of vanes positioned within the casing, each row having a frusto-conical shroud ring engaging with and supporting the outer ends of the vanes of the row, said shroud ring being split substantially diametrically, and spacer rings between axially adjacent shroud rings to maintain the required axial spacing between the rows of vanes such that each shroud ring is positioned within one of said frusto-conical inner surfaces of said casing, each of said shroud rings being of less outer diameter than the inner diameter of said frustoconical inner surface within which it is positioned so that a substantial clearance exists therebetween, said spacer rings being circumferentially continuous and having piloting means at each end engaging adjacent inner cylindrical surfaces of the casing to maintain the concentricity of the spacer rings and means interlocking said spacer rings with said shroud rings tol prevent relative rotation therebetween and to maintain concentricity therebetween, and interlocking means joining said spacers and shroud rings with said casing to prevent relative rotation therebetween.

References (lited in the file of this patent UNITED STATES PATENTS 1,692,537 Baumann Nov. 20, 1928 2,434,935 Kroon Jan. 27, 1948 2,445,661 Constant et al. `luly 20, 1948 2,488,867 Judson Nov. 22, 1949 FOREIGN PATENTS 233,643 Switzerland Nov. 16, 1944 586,562 Great Britain Mar. 24, 1947 622,895 Great Britain May 9, 1949