US2695767A

US2695767A - Turbocharger

Info

Publication number: US2695767A
Application number: US217192A
Authority: US
Inventors: Malcolm L Land; Sylvester F Brust
Original assignee: Elliott Co
Current assignee: Elliott Co
Priority date: 1951-03-23
Filing date: 1951-03-23
Publication date: 1954-11-30
Anticipated expiration: 1971-11-30

Description

NOV. 30, 1954 M, L, LAND TAL 2,695,767

TURBOCHARGER Filed March 25, 1951 A IHIM Q Whelgmp I l l Yw. vesrsn? lf" Enum' 74M, Mmm/JAM THE/l? Hrm/eus P:

United States Patent O TURBOCHARGER Malcolm L. Land and Sylvester F. Brust, Jeannette, Pa.,

assignors to Elliott Company, Jeannette, Pa., a corporation of Pennsylvania Application March 23, 1951, Serial No. 217,192

Claims. (Cl. 253-78) This invention relates to high temperature rotating machinery, and more particularly to gas turbine nozzle rings and the manner in which they are connected to the turbine inlet casings, especially of turbochargers.

In the operation of turbochargers, for example, many of them are subject to frequent cyclic temperature variations because they are used with engines that are frequently started and stopped. One example of such a situation is found in diesel locomotives. In turbochargers a gas turbine inlet casing has its inner end connected to a stationary nozzle ring. The nozzle ring has a hub from which guide blades project, the outer ends of the blades being mounted in an encircling shroud ring. The hub is rigidly connected to the inlet casing, and it is preferred to connect the shroud ring to the same casing in such a way that it can not move axially but can expand radially relative to the casing when the nozzle ring is heated faster than the casing. Even with such provision for expansion, however, the guide blades often buckle and fracture where they are attached to the hub and shroud. This is because the blades, being much thinner than the hub and shroud ring of the nozzle ring, heat and cool much more rapidly under cyclic temperature variations then the adjoining parts of the nozzle ring. Also, the nozzle ring hub is subject to a radial temperature gradient, particularly during the cyclic temperature variations. This temperature gradient often is severe enough to cause cracking of the hub.

`It is among the objects of this invention to provide a gas turbine in which the nozzle ring guide blades will not fail due to cyclic temperature variations, in which the danger ofthe radial temperature gradient in the nozzle ring hub causing cracking of the hub is greatly reduced, and in which the nozzle ring is attached to the inner end of the turbine inlet casing in a simple but effective way.

In accordance with this invention a gas turbine nozzle ring, which includes guide blades mounted between a hub and an annular shroud, has its hub fastened to the inner end of the turbine inlet casing. The outside of the shroud is provided with a plurality of circumferentially spaced radial lugs extending around it and slidably received in inner radial recesses in lugs extending across the shroud lugs from the inner end of the casing. The cooperating lugs hold the shroud against the casing, but the recesses are deep enough to leave space between the outer surfaces of the shroud lugs and the surrounding surfaces of the casing lugs to permit movement of the shroud lugs outward in the recesses when the nozzle ring expands radially relative to the casing. Furthermore, the shroud is provided at circumferentially spaced points with slits extending across it between its blades to separate it into segments that can be moved radially outward by the blades when the blades expand faster than the shroud, as they do when the turbine is subject to frequent cyclic temperature variations. Also, the nozzle ring hub is provided with a plurality of circumferentially spaced radial slots extending outward from its inner diameter part way through the hub to help keep the hub from cracking during cyclic temperature variations.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which FigA l is a side view of a turbocharger with its turbine inlet casing shown in section; Fig. 2 is a cross section taken on the line II-II of Fig. l, but with the turbine wheel removed; and Fig. 3 is a fragmentary cross section taken on the line Ill-III of Fig. 2.

Referring to the drawings, the turbocharger includes a ice blower casing 1 through which air is driven at high velocity by an impeller (not shown) mounted on one end of a shaft that is driven by a turbine wheel 2 on its opposite end. The turbine wheel is located in a turbine casing 3, to which hot gases are delivered through passages 4 (Fig. 3) in an inlet casing 5 which is axially aligned with the turbine wheel. In order to properly direct the gases against the blades 7 of the wheel, a nozzle ring 8 is disposed between the inner end of the inlet casing and the wheel. This ring has a hub 9 which is connected by bolts 10 to the inlet casing. The hub supports a series of guide blades 11 that are curved transversely and inclined to its axis. The outer ends of these blades are mounted in a shroud ring 12 which extends inward across the outer ends of the turbine wheel blades 7.

When this turbocharger is used where it is frequently started and stopped, the hub 9 of the nozzle ring is subject to a radial temperature gradient that may be severe enough to cause it to crack. The severity of this condition can be reduced materially by providing the hub with a plurality of radial slots 14 extending from its inner diameter outward part way through the hub, as shown in Fig. 2. The outer ends of the slots terminate in circular holes 15 of rather large diameter extending through the hub. These holes minimize the possibility of crack progression beyond the outer ends of the slots. For best results, it is preferred to have one slot midway between each pair of bolts 10.

ln accordance with this invention, means also is provided to permit expansion and contraction of the nozzle guide blades 11 radially of the nozzle ring without restraint by the shroud ring and without the shroud ring separating from the casing. For this purpose the outside of shroud 12 is provided with a plurality of circumferentially spaced radial lugs 17 that extend around it short distances, preferably at the end of the shroud next to the inlet casing. The outer surfaces of these lugs form arcs of a circle concentric with the shroud ring. Also, the inner end of the inlet casing has a lug 18 extending across each of the shroud lugs and provided with an inner radial recess 19 that receives the adjoining shroud lug. The radial surfaces of the recesses and shroud lugs farthest from the inlet casing engage each other to hold the shroud in tight sliding engagement with the inner end of the casing. As shown in Fig, 3, the lug recesses 19 are deep enough to leave spaces between the arcuate outer surfaces of the shroud lugs and the surrounding surfaces of the casing lugs. These spaces allow unrestrained expansion of the nozzle ring radially relative to the inlet casing.

.A further feature is that the nozzle ring shroud 12 is provided at circumferentially spaced points with slits 21 extending diagonally across it between adjacent pairs of guide blades 11 to separate the shroud ring into segments. Consequently, whenever the guide blades expand radially of the nozzle ring faster than the shroud ring, those blades can move the different segments of the shroud bodily outward radially of the nozzle ring, the shroud lugs sliding outward in the casing lug recesses 19 to permit such movement. It is preferred to so position each slit 21 that it will pass through one of the shroud lugs, so that the lug end of the slit will be straddled by the adjoining casing lug. In this way both ends of each segment of the shroud ring are held against the inner end of the inlet casing by the casing lugs at the opposite ends of that segment.

In assembling the nozzle ring with the inlet casing, the ring is placed against the inner end of the casing with the shroud lugs between the casing lugs. Then the nozzle ring is turned on its axis until the shroud lugs have slid into the casing lug recesses. At that time the bolt holes in the nozzle ring hub are in alignment with the bolt holes in the inlet casing, and bolts 10 can be inserted and tightened to hold the hub tightly against the casing and to prevent the nozzle ring from rotating out of position. No bolts are required for holding the shroud ring against the inlet casing, for the interengaging lugs will do that,

According to the provisions of the patent statutes, we have explained the principle of our invention and have illustrated and described whatwe now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specitically illustrated and described.

We claim:

l. In high temperature rotating machinery, a gas turbine inlet casing, a nozzle ring at the inner end of the casing including guide blades mounted between a hub and an annular shroud, and means fastening the hub to the casing, the outside of the shroud being provided with a plurality of circumferentially spaced radial lugs extending around it, the inner end of the casing having a lug extending across each of the shroud lugs and provided with an inner radial recess slidably receiving the adjoining shroud lug to hold the shroud against the inner end of the casing, said recesses being deep enough to leave space between the outer surfaces of the shroud lugs and the surrounding surfaces of the casing lugs to permit movement of the shroud lugs outward in the recesses when the nozzle ring expands radially relative to said casing, and the shroud being provided at circumferentially spaced points with slits extending across it between said blades to separate it into segments that can be moved radially outward by the blades when the blades expand faster than the shroud, the shroud lugs being spaced far enough apart to accommodate the casing lugs between them in case the nozzle ring is rotated relative to the inlet casing after said hub has been unfastened from the casing, whereby the shroud lugs can be disconnected from the casing lugs.

2. In high temperature rotating machinery, a gas turbine inlet casing, a nozzle ring engaging the inner end of the casing including guide blades mounted between a hub and an annular shroud, and means fastening the hub to the casing, the outside of the shroud being provided at its casing end with a plurality of circumferentially spaced radial lugs extending substantially parallel to the ends of the shroud, the inner end of the casing having a lug extending across each of the shroud lugs and provided with an inner radial recess slidably receiving the adjoining shroud lug to hold the shroud against the inner end of the casing, said recesses being deep venough to leave space between the outer surfaces of the shroud lugs and the surrounding surfaces of the casing lugs to permit movement of the shroud lugs outward in the recesses when the nozzle ring expands radially relative to-said casing, and the shroud being provided at circumferentially spaced points with slits extending across it between said blades to separate it into segments thatlcan be moved radially outward by the blades when the blades expand faster than the shroud, the shroud lugs being spaced far enough apart to accommodate the casing lugs between them in case the nozzle ring is rotated relative to the inlet casing after said hub has been unfastened from the casing, whereby the shroud lugs can be disconnected from the casing lugs.

3. In high temperature rotating machinery, a gas turbine inlet casing, a nozzle ring at the inner end of the casing including guide blades mounted between a hub and an annular shroud, and means fastening the hub to the casing, the outside of the shroud being provided with a plurality of circumferentially spaced radial lugs extending around it, the inner end of the casing having a lug extending -'across each of the shroud lugs and provided with an inner radial recess slidably receiving the adjoining shroud lug to hold the shroud against the inner end of the casing, said recesses being deep enough to leave space between the outer surfaces of the shroud lugs and the surrounding sur faces of the casing lugs to permit movement of the shroud lugs outward in the recesses when the nozzle ring expands radially relative to said casing, and the shroud being provided at circumferentially spaced points with slits extending across it between said blades and through said shroud lugs to separate the shroud into segments that can be moved radially outward by the blades when the blades expand faster than the shroud, both parts of each slit shroud lug being received in the recess of the casing lug engaging that shroud lug, whereby each casing lug straddles one of said slits.

4. In high temperature rotating machinery, a gas turbine inlet casing, a nozzle ring at the inner end of the casing including guide blades mounted between a hub and an annular shroud, and means fastening the hub to the casing, the hub being provided with a' plurality of circumferentially spaced radial slots extending outward from its inner diameter only part way through the hub, the outside of the shroud being provided with a plurality of circumferentially spaced radial lugs extending around it, the inner end of the casing having a lug extending across each of the shroud lugs and provided with an inner. radial recess slidably receiving the adjoining shroud lug to hold the shroud against the inner end of the casing, said recesses being deep enough to leave space between the outer surfaces of the shroud lugs and the surrounding surfaces of the casing lugs to permit movement of the shroud lugs outward in the recesses when the nozzle ring expands radially relative to said casing, and the shroud being provided at circumferentially spaced points with slits extending across it between said blades to separate it into segments that can be moved radially outward by the blades when the blades expand faster than the shroud.

5. In high temperature rotating machinery, a gas turbine inlet casing, a nozzle ring at the inner end ofv the casing including guide blades mounted between a hub and an annular shroud, and means fastening the hub to the casing, the hub being provided with a plurality of circumferentially spaced holes through it and radial slots extending from the holes to the inside of the hub, the outside of the shroud being provided with a plurality of circumferentially spaced radial lugs extending around it, the inner end of the casing having a lug extending across each of the shroud lugs and provided with an inner radial recess slidably receiving the adjoining shroud lug to hold the shroud against the inner end of the casing, said recesses being deep enough to leave space between the outer surfaces of the shroud lugs and the surrounding surfaces of the casing lugs to permit movement of the shroud lugs outward in the recesses when the nozzle ring expands radially relative to said casing.

References Cited in the ile of this patent UNITED STATES PATENTS Number Name Date 596,792 Schmidt Jan. 4, 1898 1,267,872 Junggren May 28, 1918 1,378,464 Junggren May 17, 1921 1,670,452 Kaehler May 22, 1928 2,296,702 Butler et al. Sept. 22, 1942 2,527,445 Pentheny Oct. 24, 1950 2,625,013 Howard et al. Jan. 13, 1953 FOREIGN PATENTS Number Country Date 107,788 Sweden June 29, 1943 726,951 Germany Oct. 23, 1942