US2851246A

US2851246A - Turbine or compressor construction and method of assembly

Info

Publication number: US2851246A
Application number: US618154A
Authority: US
Inventors: Arnold D Nichols
Original assignee: United Aircraft Corp
Current assignee: RTX Corp
Priority date: 1956-10-24
Filing date: 1956-10-24
Publication date: 1958-09-09
Anticipated expiration: 1975-09-09

Description

Sept. 9, 1958 A. D. NICHOLS TURBINE OR COMPRESSOR CONSTRUCTION AND METHOD OF ASSEMBLY Filed Oct. 24, 1956 2 Sheets-Sheet 1 I d w v M Z 6 m m U f. /2 il 01 Wm MN M 1 w w d M K o film //H N R A7 a w v v W 5 TURBINE 0R COMPRESSOR CONSTRUCTION AND METHOD OF ASSEMBLY Filed Oct. 24, 1956 Sept. 9, 1958 A. D. NICHOLS 2 Sheets-Sheet 2 FIG-3 ARNOLD mm s ATTORNEY TURBINE OR COMPRESSOR CGNSTRUCTIGN AND METHOD OF ASSEMBLY Arnold D. Nichols, Newington, Conn, assignor to United Aircraft Corporation, East Hartford, ileum, a corporation of Delaware Application @ctoher 24, 1956, Serial No. 618,154

6 Claims. (Cl. 253--78) This invention relates to compressor or turbine construction and more particularly to such construction when used with a one-piece outer case.

The benefit derived from a one-piece turbine or compressor case is the elimination of the sealing problems caused by the use of intermediate circumferential or axial flanges in the case and the elimination of the weight of the extra metal necessary to form these intermediate or axial flanges and the parts used to secure these flanges together, the securing part being nuts and bolts, clamps or other securing means. My invention permits the use of a one-piece turbine or compressor case in an installation which is easily assembled and further permits the support of the inter-rotor gas or air diaphragm and seal by the stator vanes, all in such a fashion that difierential thermal expansion is permitted between the rotary and stationary parts and further between the diaphragm and the vanes.

It is an object of this invention to provide a light weight compressor or turbine construction utilizing a one-piece outer case in which the axial loads on the turbine or compressor vanes are transmitted to the outer case.

It is a further object of this invention to provide a vane construction which is light in weight and which supports an inter-rotor diaphragm and air seal unit.

It is a further object of this invention to provide a'vane construction in which the Vane is held axially by annular depressions in the outer case and in which the vane is held radially by at least one of the annular depressions and a retaining ring in which construction the vanes must be assembled at an-angle, with its inner shroud platform farther forward than its outer shroud platfiorm and then, when all vanes are in this angular position, engaging the air seal and diaphragm and partially engaging the outer case annular depressions, the vanes may be brought into proper radial position by moving the diaphragm rearwardly, thereby causing the vane to securely engage the case annular recesses.

Other objects and advantages will be apparent from the specification and claims, and from the accompanying drawings which illustratean embodiment of the invention.

In thedrawings:

Fig. 1 shows a cross-sectional view of a typical'aircraft turbojet engine which might use the'subject matter of my invention.

Fig. 2 is an enlarged and detailed cross-sectional showing of the turbine section of the engine shown in Fig. 'l embodying my invention.

Fig. 3 is a fragmentary cross-sectionalview of the second stage stator of my invention to illustrate the assembly method. a

Fig. 4 is a view taken along line 4-4 of Fig. 2.

Referring to Fig. 1, we see aircraft turbojet engine comprising air inlet section 12, compressor section 14, combustion section 16, turbine sectionlSyexhaust or 'dis charge duct and exhaust outlet 22. Air enters air inlet Section 12 and is compressed as it passes through com- States Patent 0 Patented Sept. 9, 1958 pressor section 14 then is heated by combustion chambers 24 as it passes through combustion section 16. Fuel enters combustion chamber 24 through fuel nozzles 26 which are provided fuel by fuel manifold 28. Spark plug 30 or other ignition means may be used to ignite the atomized fuel which enters combustion chamber 24.

After leaving combustion section 16, the heated gases pass through turbine section 18 and thence through exhaust discharge duct 20. After passing through discharge duct 20 the heated powerplant or engine gases are discharged into the atmosphere through exhaust outlet 22 thereby producing thrust. As in standard construction, inlet section 12, compressor section 14, combustion section 16, turbine section 18, exhaust or discharge duct 20, and exhaust outlet 22 are of substantially circular crosssection.

Referring to Fig. 2, a turbine construction is shown to clearly illustrate the subject matter of my invention but it should be borne in mind that a turbine construction was chosen solely for purposes of illustration and that the invention is equally applicable to a compressor or any other type of mechanism utilizing spaced rotary units, such as compressor and turbine disc units, with stationary stator units which normally comprises a plurality of circumferentially spaced stationary vanes with a diaphragm and air seal unit attached thereto, spaced therebetween.

As shown in Fig. 2, the heated engine or powerplant gases, after leaving combustion chamber 24 of combustion section 15, pass through transition section 36 into a'nnular area 38 and thence through turbine unit 18 and thence into discharge or exhaust duct 20 to be discharged thru exhaust outlet 22.

Turbine unit 18 comprises a stationary part and a rotary part. The stationary part consists of one-piece outer turbine case 40 together with the first stage stator unit 42, the second stage stator unit 44, and the third stage stator unit 46. First stage stator unit 42 comprises a plurality of circumfe'rentially spaced vanes 48 which have platform sections 50 at their outer ends and platform sections 52 at their inner ends which abut corresponding platform sections of adjacent first stage stator vanes to form the outer and inner gas flow periphery of the first stage stator 42. The outer platform Stl has outwardly extending

lugs

54 and 56 thereon which are received in annular recess 58 of outer turbine case 40. Pin 60 circumferentially positions vanes 48 as it slideably engages radial slot 61. The inner platform 52 of vanes 48 carries

lugs

62 and 64 which are received in inwardly directed annular recess 66 formed by annular ring 68 which is bolted through attachment means 70 to flange 72 on turbine inner case '71. In this fashion, the plurality of circumferentially spaced vanes 48 of first stage stator unit 42 are fixed in position yet permitted to expand radially with respect to turbine case 40. It will further be observed that during powerplant assembly, with one-piece turbine case 48 attached thru securing means 74 to outer case 76 ofcombustion section 16, vanes 48 may be installed from the after end of engine it by first engaging outer annular recess 58 and then attaching retaining ring 68 to flange 72, thereby positioning the plurality of vanes 48. The second stage stator 44 is spaced axially between the first stage stator42 and .the third stage stator 46 and comprises a plurality of circumferentially spaced vanes 78 which have outer platform sections 88 and inner platform sections 84 which abut corresponding platforms of adjacent vanes 78 to form outer and inner vane shrouds for second stage stator 44. which shrouds definetheinner and outer gas flow periphery of the second stage stator 44.- Outer platform section 8t has'forward lug 86 and after lug 88 attached thereto and designed to be received in forward annular depression 90 and after annular depression 92 of outer case 40, respectively. It will be noted that forward annular depression opens axially at its rearward end so that it may be said to be opened rearward axially while after annular depression 92 opens radially inward. Retaining ring 94 engages surface 96 of lug 88 and further engages surface 98 of case 48 to radially position vanes '78 with respect to case 40 in corn bination with the action of the receipt of lug 86 in forward annular depression 90. With this lug construction, the thrust load on vanes 78 are transferred thru outer case 40. The vane thrust load is normally axially downstream since the gas pressure upstream of vanes 78 exceeds the gas pressure downstream thereof. inner shroud 84 has inwardly directed radial projections 180 attached thereto. While projections 100 may be of any convenient cross-section, rectangular cross-section is acceptable, and projections 100 may have recess 102 machined therein for weight saving purposes. The plurality of inwardly directed radial projections 100 proj cting from vanes 78 of the second stage stator unit 44 perform the function of positioning and supporting diaphragm unit 184. Diaphragm unit 184 comprises substantially radially extending annular ring or disc 106 which may be of sheet metal construction and which carries flange unit 108 at its outer periphery. Flange unit 108 consists of radially directed flange 110 which combines with inner platform sections 84 of vanes 78 to form the inner shroud of the second stage stator unit 44 and abuts the forward end of inner platform 84 to partly axially position the inner end of vanes 78. Flange unit 108 further consists of substantially axially extending circular flange 112 which has a plurality of axially extending slots 114 therein, which slots 114 culminate in substantially radially extending

walls

116 and 118. Slot 114 relatively snugly engages projections 100 in the circumferential direction, but it will be noted that

walls

116 and 118 of slot 114 are spaced axially a substantially greater distance than the axial dimension of projections 100. This is to permit vane assembly, to be described later. Diaphragm unit 104 carries air seal 120 which carries knife-

edge seals

122, 124 and 126. Knife-

edge seals

122, 124 and 126 are held in air or gas sealing relation to complementary projections or

platforms

128 and 130 which project from first stage rotor unit 132 and second stage rotor unit 134, respectively. The function of diaphragm unit 104 and air seal 120 is to provide a controlled clearance to control the amount of cooling air being emitted from area 77. The cooling air is used to cool the surfaces of rotor discs 132 and 134. Third stage stator unit 46 is constructed in substantially the same fashion as second stage stator unit 44 and comprises a plurality of circumferentially spaced vanes 138 having outer shroud forming the platforms 140 with

lugs

142 and 144 attached thereto to be received in

annular depressions

146 and 148 of one-piece turbine case 40. Vanes 138 also have inner platform sections 150 which form the inner shroud and carry radial inward projections 152, which are received in slots 154 of axially extending flange 156 of diaphragm unit 158 in the same fashion as described for the second stage stator unit 44. Diaphragm unit 158 is of substantially the same construction as diaphragm unit 104 and carries sealing platform 160 at its inner periphery to engage in sealing relation knife edges 162, 164 and 166 of air seal 168 which rotates with second and third stage rotor units 134 and 136. It should be understood that diaphragm unit 158 could as easily carry knife-edge seals and position them in air sealing relation to a sealing platform as is done by diaphragm unit 104.

As regards the turbine rotary unit, while I choose to show a spool type turbine. rotor as described and claimed in U. S. Patent No. 2,747,367 in which first stage rotor unit 132 operates mechanically and independently of jointed second and third stage rotor units 134 and 136, the rotary turbine unit could be fully mechanically attached as shown in U. S. Patent No. 2,711,631.

By way of assembly, the powerplant 10 may be assembled in a vertical position with the turbine section vertically above the compressor section. When the compressor and burner sections have been assembled, outer onepiece turbine case 40 may be placed against flange 170 and then attachment nut and bolt units 74 can be used to attach case 40 to case 76 of combustion section 16 since case 76 is of telescopic construction and can also be fastened rigidly at its forward end. With case 40 in position, the first stage stator unit 42 can be assembled as previously described. First stage rotor unit 132, together with outer concentric shaft 172, can then be assembled into the position shown in Fig. 2, air seal 174 being in position prior to the installation of rotor 132 and sh aft 172 which are installed assembled. Spacer ring 176 is then placed in position as shown in Fig. 2 with radially directed teeth 178 engaging complementary recesses 180 of case 40 to prevent rotation of spacer ring 176. Connecting means 177 joins shaft 172 to rotor 132. Flat ring 182 is then placed in position and diaphragm unit 184 is placed in position forward of its normal position as best shown in Fig. 3. The function of ring 182 is to block gas gaps between the vanes 78 which are downstream of it. Diaphragm unit 104 is then inserted. Each of the plurality of vanes 78 is then brought into the position shown in Fig. 3 in which projections 100 engage slots 114 in flange 112 and with the inner end of vane 78 in a position axially forward of the outer end of vanes 78 and with

lugs

86 and 88 partially engaging annular depressions 90 and 92 of outer case 40. When all vanes 78 are in this angular yet circumferentially correct position diaphragm unit 104 is drawn rearwardly to its proper position while the outer ends of vanes 78 are prevented from moving rearwardly, thereby causing vanes 78 to pivot in a clockwise direction to bring

lugs

86 and 88 into full retention position within annular depressions 90 and 92 while the forward edge 184 of inner shroud 84 bears against surface 186 of flange 108 of diaphragm unit 104, and while surface 188 of projection 100 bears against wall 116 of slot 114. In this position, the plurality of projections 100 position and support diaphragm unit 104. Retaining ring 94 is then assembled to bear against surface 96 of vane 78 and to further bear against surface 98 of case 40 to combine with the action of lug 86 as it bears against surface 190 of case 40 to radially position vanes 78. Spacer ring 192 is then placed in position between sealing rings 94 and 194. Second stage rotor unit 134 may then be placed in a position against flange 196 of inner concentric shaft 198 while bolt 200 projects rearwardly therethrough. Spacer 202 and seal carrying ring 204 may then be assembled about bolt 200. Third stage stator unit 46 comprising vanes 138 and diaphragm unit 158 may then be assembled in a position as shown in Fig. 2. Thrust ring 206 may then be assembled as shown, and spacer ring 208 then assembled. Ring 208 contains axially extending detents 210 which receives radial prot ctions 212 of thrust ring 208 to prevent the rotation of seal 208. Third stage rotor unit 136 may then be placed in position along with rear turbine shaft 216 and nut units 218 used with bolt 200 to connect rotor units 134 and 136. Discharge duct 20 may then be brought into position and bolted to turbine case 40 by means of nut and bolt units 220. Ap-

plicant has accomplished the use of a one-piece turbine case, which case carries the full thrust loads of all vane units, except part of vanes 48 load which is carried thru case 71, and does away with leakage encountered due to circumferential flanges in the middle of the turbine case and the added weight caused by the flange metal. Turbine case 40 has flanges only at its forward and after end and is, as previously stated, of one-piece construction.

The heart of applicants invention lies in providing a stator or vane construction which permits the use of a one-piece turbine or compressor housing which is fully assembleable with the powerplant in a vertical position and which permits the thrust loading on the vanes to be transmitted to the housing instead of to other less substantial parts and which further permits vane support of the air diaphragm and seal. It will be evident to one skilled in the art that assembly with the powerplant in the horizontal position is also possible with this construction provided that support fixtures are used to hold the rotating units in position during assembly.

It will be evident that while applicant shows but one vane construction of the type claimed in the turbine configuration shown in Fig. 2, such construction could be used on any number of stator units, indeed, it could be used on third stage stator unit 46 in Fig. 2 excepting that a flange connection is already provided to connect exhaust duct 20 to turbine case 40.

It should be noted that a single vane, such as 78, may be removed and replaced by removing the rotors and stators downstream of the vane, then removing ring 94, then moving diaphragm seal unit 104 forward to rotate vanes 78 counterclockwise and then removing and replacing any one of the vanes 78.

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

I claim:

1. A turbine or compressor construction having an axis and comprising a one-piece case having a rearwardly opening annular depression in its inner surface and further having an inwardly opening annular depression in its inner surface spaced rearwardly from said rearwardly opening annular depression, a support ring contained within and concentric with said case and having a plurality of circumferentially spaced slots therein, a plurality of radially directed circumferentially spaced vanes each having inner and outer platforms which abut corresponding platforms of adjacent vanes and each having at its outer end a forwardly projecting lug and an outwardly projecting lug having a rearwardly projecting lip and with said outwardly projecting lug spaced rearwardly from said forwardly projecting lug and with said vane forwardly directed lug engaging said case rearwardly opening annular depression to radially position the forward end of said vane and with said vane outwardly directed lug engaging said case inwardly opening annular depression to axially position said vane and further having radial projections extending inwardly from their inner ends which projections loosely engage the slots of said support ring to support said support ring and permit radial motion between said support ring and said vane, and a retaining ring engaging the inner surface of said case and further engaging the inner surface of said rearwardly projecting lip to radially position the rearward end of said vane.

2. Apparatus of the turbine or compressor type comprising a one-piece outer case having two axially spaced annuler depressions in its inner surface, a plurality of circumferentially spaced vanes each having inner and outer shrouds which abut corresponding shrouds of adjacent vanes and each having a forward and after lug at their outer ends engaging said annular depressions and further having radial projections extending inwardly from said inner shrouds, a retaining ring engaging the inner surface of said case and further engaging said after lugs to radially retain said vanes, 21 substantially radially extending annular ring diaphragm extending substantially radially inward from said vanes and having a flange with spaced axial slots at its outer end which slots receive said vane radial projections to position and support said diaphragm, and a sealing ring attached to said diaphragm and having knife-edge radially extending seals projecting inwardly therefrom.

3. Apparatus of the turbine of compressor type comprising a one-piece outer case having two axially spaced annular depressions in its inner surface, at least two rotatable axially spaced discs each carrying a series of outer ends engaging said annular depressions and further 1 having radial projections extending inwardly from said inner shrouds, a retaining ring engaging the inner surface of said case and further engaging said after lugs to radially retain said vanes, a substantially radially extending diaphragm in the form of an annular disc extending from said vanes to said sealing projections and having a flange with spaced axial slots at its outer end which slots receive said vane radial projections to position and support said diaphragm, and a sealing ring attached to said diaphragm and having knife-edge projections located in air sealing relation to said disc sealing projections.

4. Apparatus of the turbine or compressor type comprising a one-piece outer case having a rearwardly opening annular depression in its inner surface and further having an inwardly opening annular depression in its inner surface spaced axially from said rearwardly opening annular depression, at least two rotatable axially spaced discs each carrying a series of blades at their outer periphery and having complementary sealing projections between said discs, a plurality of circumferentially spaced vanes each having inner and outer shrouds which abut corresponding shrouds of adjacent vanes and each having a forward and after lug at their outer ends engaging said annular depressions and further having radial projections extending inwardly from said inner shrouds, a retaining ring engaging the inner surface of said case and further engaging said after lugs to radially retain said vanes, a substantially radially extending diaphragm in the form of an annular disc extending from said vanes to said sealing projections and having a flange with circumferentially spaced axial slots at its outer end which slots receive said vane radial projections to position and support said diaphragm, and a sealing ring attached to said diaphragm and having knife-edge projections located in air sealing relation to said disc sealing projections.

5. Apparatus of the turbine or compressor type comprising a one-piece outer case having an axially extending rearwardly opening annular depression in its inner surface and further having an inwardly opening annular depression in its inner surface spaced axially downstream from said rearwardly opening annular depression, at least two rotatable axially spaced discs each carrying a series of blades at their outer periphery and having complementary sealing projections between said discs, a plurality of circumferentially spaced vanes each having inner and. outer platforms which abut corresponding platforms of adjacent vanes and each having an axially extending forwardly projecting lug at the forward edge of its outer end and further having an axially extending rearwardly projecting lug at the after edge of its outer end with said forwardly projecting lug engaging said rearwardly opening annular depression while said rearwardly projecting lug engages said inwardly opening annular depression and further having radial projections extending inwardly from said inner platform, a retaining ring engaging the inner surface of said case and further engaging said rearwardly projecting lugs to radially retain said vanes, a substantially radially extending diaphragm in the form of an annular disc extending from said vanes to said sealing projections and having a flange with circumferentially spaced axial slots at its outer end which slots receive said vane radial projections to position and support said diaphragm, and a sealing ring attached to said diaphragm, and having knife-edge projections located in air sealing relation to said disc sealing projections.

6. Apparatus of the turbine or compressor type comprising a one-piece outer case having an axially'extending rearwardly opening annular depression in its inner =4 surface and further having an inwardly opening annular depression in its inner surface spaced axially downstream from said rearwardly opening annular depression, at least two rotatable axially spaced discs each carrying a series of blades at their outer periphery and having complementary sealing projections between said discs, a plurality of circumferentially spaced vanes each having inner and outer platforms which abut corresponding platforms of adjacent vanes and each having an axially extending forwardly projecting lug at the forward edge of its outer end and further having an axially extending rearwardly projecting lug at the after edge of its outer end with said forwardly projecting lug engaging said rearwardly opening annular depression while said rearwardly projecting lug engages said inwardly opening annular depression and further having radial projections extending inwardly from said inner shrouds, a retaining ring engaging the inner surface of said case and further engaging said rearwardly projecting lugs to radially retain said vanes, a substantially radially extending diaphragm in the form of an annular disc extending from said vanes to said sealing projections and having a flange with circumferentially spaced axial slots of greater axial dimension than the axial dimension of said vane radial projections at its outer end which slots receive said vane radial projections to position and support said diaphrgam, a sealing ring attached to said diaphragm and having knife-edge projections located in air sealing relation to said disc sealing projections and a circumferential sealing ring abutting the forward outer platforms of said vanes to prevent gas leakage therebetween.

References Cited in the file of this patent UNITED STATES PATENTS 2,749,026 Hasbrouck et al June 5, 1956 FOREIGN PATENTS 160,174 Australia Dec. 8, 1954 652,150 Great Britain Apr. 18, 1951