US3311345A - Vane construction - Google Patents

Description

March 28, 1967 H. KREBS 3,311,345

VANE CONSTRUCTION Filed Sept. 27, 1965 INVENTOR HANS KHEBS I f AHUHMI 12/ United States Patent 3,311,345 VANE CGNSTRUUIION Hans Krebs, Stuttgart-Zuifenhausen, Germany, assignor to Daimler-Benz Aktiengesellschaft, Stuttgart-Unterturkheim, Germany Filed Sept. 27, 1965, Ser. No. 490,260 Claims priority, application Germany, Oct. 2, 1964, 1) 45,544 1 Claim. (Cl. 253-78) The present invention relates to a guide blade ring for turbines or compressors of gas-turbine propulsion units with an inner and outer cover or support ring for the fastening of the individual blades or vanes, which at both ends thereof are inserted into corresponding slots in the two end rings.

Guide blade rings for turbines and compressors of gasturbine propulsion units are known in different realizations. With guide vanes or blades having base portions, the latter form, placed one adjacent the other, the inner boundary of the flow channel and are connected thereat with each other in the circumferential direction. Guide blade rings of the aforementioned type for turbines are thereby provided with a radially inwardly extending ring which serves as support for the labyrinth seals which cooperate with the turbine shaft.

Guide vanes or blades with base or foot portions are generally quite complicated and expensive in their manufacture. This disadvantage is avoided by guide blades without base or foot portions. With the use of the latter 7 type of guide blades or vanes, the guide blade ring consists, in addition to the outer cover or support ring, also of an inner cover or support ring, into which are inserted the inner ends of the guide vanes or blades with relatively long tab-like extensions in correspondingly shaped slots, whereby the securing tabs are bent, wedged-over, or peened-over and the inner edges of the blades, properly speaking, rest without play on the inner cover or support ring. The outer ends of the guide vanes or blades are merely inserted into the outer cover or support ring in correspondingly shaped slots so that during operation the guide vanes or blades can freely expand in the radial direction as a result of the influence of heat. With the use of an undivided, unitary inner cover or support ring, there exists with this type of construction the necessity to slide the guide blades, during assembly of the latter, at first in the radial direction at least by the length of the inner securing tab or lug, radially outward into the slots of the outer cover band in order to be able to assemble the inner cover or support ring. Subsequent thereto, the

individual guide vanes or blades are again inserted in the radial inward direction into the slots provided within the inner cover or support ring. The need for temporarily sliding the guide blades radially outwardly in the outer cover or support ring by at least the height of the securing tabs or lugs entails the disadvantage that the outer blade ends, within the area of the height that corresponds to the length of the securing tabs or lugs, have to be constructed without blade twists which, however, brings about a deterioration of the aerodynamic efiiciency for the blades. In order to eliminate this shortcoming, it is known to construct the outer cover or support ring of a multi-partite structure and to provide an additional gastight outer closure ring which, however, leads again to an expensive construction.

The aim of the present invention essentially consists in creating, with the elimination of the disadvantages occurring with the known constructions, simultaneously a simple and above all rigid construction of a guide blade or vane ring.

In solution to the underlying problems, it is proposed in accordance with the present invention to extend the outer ends of the guide blades approximately up to the height of the outer edges of two collars provided at the outer cover or support ring and to arrange the outer ends of the guide blades between these two collars as well as to weld the same to these two collars and to the bottom of the cover or support ring, with the contour of the welding seam also extending between the forward and rearward edges of the outer blade ends and the inner sides of the two collars of the cover or support ring, where gaps are provided for the accommodation of the welding seam whereas the inner ends of the guide blades have short extensions, which engage, adjustable in the radial direction, in corresponding apertures or slots provided within the inner cover or support ring and center the same with a spoke-like effect, whereby an expansion play is left between the radial inner edge of the blades and the annular flange of the inner cover or support ring forming the inner boundary of the flow channel.

The following advantages are connected with and derived from the present invention.

The inner and outer cover or support rings can be constructed in one piece in a simple manner. By reason of the short length of the centering extension at the inner end of the blades, the aerodynamically ineffectual height in the outer area of the guide blades or vanes, constructed without root or base portions, becomes negligible. The two collars provided at the outer circumference of the outer cover or support ring impart thereto a high rigidity and are suited in particular to assure an unusually strong and rigid connection between the outer ends of the guide blades and the outer support ring. T his extremely sturdy and rigid connnection is achieved by the welding seam, drawn up along the forward and rearward edges of the guide blades or vanes, and by the relatively large clamping height provided at these places (with this height a multiple of the sheet metal thickness of the outer cover or support ring), which produces a high resistance in the axial direction in which occur large forces resulting from the gas flow that seek to press the inner cover or support ring against the adjoining wheel or rotor. The play between the bottom edge of the guide blades and the annular flange of the inner cover or support ring forming the inner boundary of the flow channel assures a free expansion possibility between the latter and the guide blades. Additionally, the present invention permits simple and rapid assembly possibilities. Finally, notwithstanding the existing expansion possibility for the inner cover or support ring, the concentric position thereof is always assured by the spoke effect of all guide blades.

Accordingly, it is an object of the present invention to provide a blade or vane ring construction for turbines or compressors of gas-turbine drive units which is simple in construction yet avoids the aforementioned shortcomings and drawbacks encountered with the prior art constructions.

It is another object of the present invention to provide a vane or blade ring for turbines or compressors which obviates the need of complicated and expensive support rings for the blades yet does not require base portions at the radially inner ends of the blades.

A further object of the present invention resides in a guide vane ring construction which can be assembled with great ease and speed.

Still another object of the present invention resides in the provision of a blade ring construction that is sturdy and extremely reliable in operation yet also highly efficient from an aerodynamic point of view by permitting appropriate shaping of the blades substantially over the entire length thereof.

Still a further object of the present invention resides in the provision of a vane ring construction using inner 3 and outer support rings for the vanes which eliminates the need for complicated and expensive seals.

Another object of the present invention resides in the provision of a blade ring of the type described above which is automatically centered and permits free expansion of the blades under the influence of the prevailing thermal conditions, yet permits an easy and rapid assembly.

These and further objects, features, and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one embodiment in accordance with the present invention, and wherein FIGURE 1 is a partial longitudinal axial cross-sectional view through a guide blade ring in accordance with the present invention; and

FIGURE 2 is a partial plan view on the guide blade ring of FIGURE 1, unfolded into the plane of the drawing.

Referring now to the drawing, wherein like reference numerals are used throughout the two views to designate like parts, the guide blade ring which forms part of a gas turbine propulsion unit of any suitable construction and is arranged within the engine housing of the gas-turbine propulsion unit, essentially consists of the outer cover or support ring generally designated by reference character A, of the individual guide blades or vanes generally designated by reference character B, and of the inner cover or support ring generally designated by reference character C. At the outer support ring A, two collars 11 and 12 are provided extending outwardly in the radial direction whose radial height is a multiple of the thickness of the sheet metal material of the support ring A. The part of the outer cover or support ring A which is disposed between the two collars 11 and 12 will be referred to as support ring bottom 13, in which are provided apertures or slots within which are seated the outer ends 14 of the guide blades B. A gap e is provided between the forward edge 15 of the guide blades B and the inner side 16 of the collar 11; a similar gap 1 is disposed between the rear edge 17 and the inner side 18 of the collar 12 adjacent thereto. The welding seam 19, extending about the entire guide blades B, extends through these two gaps e and f, i.e., these two gaps e and f are filled completely with a weld 19 and 19 so that at these places the clamping or height for the guide blades B amounts to a multiple compared to that at the support ring bottom 13 where the welding seam 19 has a normal thickness. The outer ends 14 of the guide blades B are constructed of U-shape as viewed transversely to the flow direction of the working medium, i.e., are matched in shape to the outer cover or support ring A (FIG. 1). This entails a decrease in weight by the corresponding aperture between the two horn-like ends of each blade. Additionally, this form also works out favorably during the mounting of the welding seam where the thus-shaped blade ends can adapt themselves better to the heat stresses and distortions that may result.

The guide blade B is provided at the inner end 20 thereof with a short extension 21 which is seated radially adjustable in apertures or slots which are provided in the annular flange 22 forming the inner boundary of the flow channel. A gap or play g is left between the inner edge 23 of the blades B and the annular flange 22 so that the guide blades B, which heat up more strongly during operation, can freely expand with respect to the inner cover or support ring C.

The assembly of the guide blade ring in accordance with the present invention takes place in the following manner:

At first, the individual guide blades B are inserted radially from the inside toward the outside into the apertures or slots provided in the bottom 13 of the outer, unitary cover or support ring A arranged horizontally on the assembly device, and more particularly so far that the inner edge 21 of the extension 21 lies ahead of the annular flange of the inner cover or support ring C also of unitary construction so that the installation and mounting thereof within the guide blades B is possible on the assembly installation. The individual guide blades B are then retracted radially inwardly into the final assembly position, i.e., the extensions 21 are threaded into the apertures or slots provided within the annular flange 22 whereby the heat expansion play g is adjusted by a suitable gauge or template. After this is done, the welding seams 19, 19 and 19 are drawn about the upper ends 14 of the individual guide blades B. In the final assembly position of the guide blades B, the outer edges 11 and 12 of the two collars 11 and 12 as well as the outer edge 14' of the guide blade ends 14 are approximately at the same height.

While I have shown and described one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to a person skilled in the art; and I, therefore, do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are encompassed by the scope of the appended claim.

I claim:

A guide blade ring for turbines and compressors of gas-turbine drive units comprising:

a plurality of guide blades,

inner and outer support ring means for securing the individual guide blades, said blades having inner and outer ends, said outer support ring means being provided with outer apertures, said outer ends of said blades being inserted in fixed positions in said outer apertures,

said inner support ring means being provided with ends of said blades being radially adjustable in said inner apertures,

said outer support ring means comprising two collars having inner sides and outer edges,

said outer ends of said blades being U-shaped and extending approximately to the radial height of said outer edges,

the leading and trailing edges of said outer ends on the one hand and said inner sides on the other defining gaps and a welded seam of varying radial height securing said outer ends to said outer support ring means including said inner sides at said gaps, the radial height of said welded seam being greatest within said gaps.

References Cited by the Examiner UNITED STATES PATENTS 2,606,741 8/ 1952 Howard.

2,681,788 6/1954 Wosika 25378 2,771,622 11/1956 Thorp 253--78 FOREIGN PATENTS 758,106 9/1956 Great Britain.

MARTIN P. SCHWADRON, Primary Examiner.

EVERETTE A. POWELL, IR., Examiner,

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