US 3269701 A
Description (OCR text may contain errors)
1956 A. J. MILLER ETAL 3,269,701
STATOR BLADE SUPPORT Filed Oct. 17, 1963 44 32 FIG. 3
IN V EN TORS ARTHUR J. MILLER. JAMES R. ANDERSON.
United States Patent Office Patented August 30, 1966 3,269,701 STATOR BLADE SUPPORT Arthur J. Miller, Irwin, and James R. Anderson, Latrobe, Pa., assiguors to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Oct. 17, 1963. Ser. No. 316,969 3 Claims. (Cl. 253-78) This invention relates broadly to fiuid machinery. More particularly. this invention relates to a blading construction of the kind employed in fluid machines, such as axial compressors or gas turbines where a stream of gas tlows through the machine in a path across which blades are disposed.
In an axial compressor of the kind illustrated in United States Letters Patent 2,823,851. a stream of gas flowing through the machine is compressed as it travels through a path including alternately arranged stator and rotor blades. The function of the rotor blades is to provide movement to the stream of gas being compressed. The stator blades are arranged in the machine for the purpose of directing gas leaving one rotor stage into the next succeeding rotor stage. The stator blades are arranged in fixed position within the compressor by attachment to a portion of the compressor structure. such as the casing.
It will be appreciated that under high pressure and high velocity conditions substantial forces are present in the gas stream flowing through the machine. It is necessary that the blading described above. particularly the stator blading. be designed so that sufficient resistance to the forces will be obtained.
This invention has as its principal object the provision of an improved stator blade construction wherein the stator blade assembly affords a high resistance to the forces created by the gas stream so that possibility of failure of the blading is minimized.
The forces involved in machinery of the kind contemplated herein are both steady. as encountered in a stable gas stream. and unsteady. where the gas stream is variable in terms of pressure and velocity. The latter forces cause severe vibration. often resulting in blading failure.
An additional object of the invention is the provision of an improved stator blade assembly of the type described wherein firm attachment of the blades to a supporting structure is insured.
A still further object of the invention is the provision of an improved stator blade configuration which inherently involves strong resistance to the bending forces encountered in a machine of the kind described.
A still further object of the invention is the provision of a novel method of fabricating a stator ring assembly whereby strong resistance to the turning forces generated by the stream of gas. in a machine of the kind described, is developed.
These and other objects of the invention will be apparent upon a consideration of the ensuing specification and drawings. in which:
FIGURE 1 is a fragmentary view of a machine of the kind utilizing a stator blade construction forming the subject of this invention:
FIGURE 2 is a side view of an improved blade used in the stator blade assembly;
FlGURE 3 is an end view of the blade illustrated in FlGURE 2:
FIGURE 4 is a side view in section of a first attachment member together with a fastening device therefor employed in the stator blade assembly;
FIGURE 5 is a side view in section of a second attachment member used in the stator blade assembly: and
FIGURE 6 is a view. partially in section. of the stator blade assembly forming the subject of this invention.
Referring more particularly to the drawings for an illustration of a preferred embodiment of this invention. it is to be noted that an axial compressor 10 of the type with which this invention may be used is illustrated in FIG- URE 1. The portion of the axial compressor 10 illustrated in FIGURE 1 includes a series of annular rotary discs 14 having rotor blades 16 circumferentially spaced about the surface so as to afford a plurality of radially extending surfaces. The rotor discs 14 are held together by through bolt 18. which in turn is carried in a support 20. Casing 22 surrounds the assembly described in spaced relation thereto so as to form a passage for the flow of gas through the machine. The gas enters the machine through inlet 24 and flows through the annular path which has a series of stator blades 28 interposed between the rotor blades 16 in the manner shown.
The stator blade assembly 26 forming a feature of this invention includes the stator blade 28 in the form of an air-foil of the kind shown in FIGURE 3. The blade 28 includes a body portion 30 extending substantially across the path through which the gas flows. Extending from the opposite ends of the body portion 30 of blade 28 are projections 32 composed of a tang or extension section 34 and an intermediate section 36 having a stepped configuration as' shown in FIGURE 2. It is to be noted that FIG- URE 2 illustrates. in dotted lines. a prior art construction which has proven to be inadequate when gas of a relatively high pressure is encountered.
Considering the stator blade assembly further, it is to be noted in FIGURE 6 that an outer support ring 38 is employed for the purpose of supporting one end of the stator blade in a manner to be later described. The outer support ring 38 is provided with a plurality of spaced radial openings 40 disposed about the periphery of the ring. Opening 40 is provided with a differential diameter defining enlarged end portions 42 and 44 and a locating shoulder 46 for purposes to be later described. Completing the stator ring assembly are a pair of annular retainer rings 48, 50, each of which is provided with an elevated central section 52.
In order that the blades 28 be secured to the support ring 38 and the retainer rings 48 and 50, there is provided a pair of attachment members as illustrated in FIGURES 4 and 5. In FIGURE 4, a first attachment member 54 is shown having an opening 56 extending therethrough. head 58 the outer surface of which is inclined, a threaded surface 60, and a shank surface 62 connecting the head 58 and the threaded surface portion 60. As illustrated in FIGURE 4, the attachment member is slotted so that it may be assembled over the projection 32 at one end of the blade 28. The inclination of the lower surface of head 58 is the same as the inclination of the edge 31 of the blade 28. Attachment member is secured to the projection 32 by welding and brazing as described hereinafter.
A second attachment member 66 is shown in FIGURE 5 and includes an opening 68 extending therethrough. In addition, there is provided on the outer surface, an annular groove 70. The upper surface 74 of the attachment member 66 is provided with an inclination which is the same as that of edge 33' of the blade 28. Second attachment member is likewise mounted on the blade by inserting the member over the tang 34 so that the upper surface thereof engages edge 33' of the blade 28. This element is also secured to the projection by welding. In this regard, it has been found that a satisfactory bond between the attachment members and the blade projections is obtained by first tack welding the outer projecting portion of the tang to the outer surface of each of the attachment members and then brazing the elements to the projections.
The sub-assembly. as defined.- is then secured to the outer ring 38 by inserting the end of the blade having attachment member 54 secured thereto into the openings 40. The parts are so constructed that the shoulder 61 between the shank 62 and the head 58 engages the shoulder 46 formed on the support member. Internally threadcd member 72 then secures the blade to the outer ring.
The retainer rings 48 and 50 are then assembled with the elevated central portion 52 in engagement with the groove 70 formed on the attachment member 66. This latter assembly is relcasably connected with fastening elements 76, shown in FIGURE 1.
It will be appreciated that the casing 22 is formed in two halves, which are subsequently bolted together to form the enclosure for the axial machine. The upper and lower halves are provided with grooves 78, into which the outer support ring 38 with the blade and retainer rings supported thereon, are introduced. Under these circumstances, it will be appreciated that the outer support ring consists of two semi-circular sections. This is also true of the configuration of the retainer rings.
With the construction described, certain advantages are obtained. For example, by utilizing the tang in the manner described, the tack welding operation in which the attachment member 54 is initially secured to the blade :nables the parts to be pre-assemhlcd so that expensive fixtures usually associated with brazing operations are avoided. The tack welding causes the attachment members to be drawn tightly against the edge of the blade. The subsequent brazing operation unites the two parts .hroughout a relatively large surface area strengthening the bond between the parts.
After assembly and during use of the stator blade construction, if failure occurs due to fracture of the parts in he area accommodating the weld union or the braze inion, the parts are prevented from separating by the hreaded connection and the retainer ring construction.
With the construction described, it has been found that t substantial resistance to the bending stresses present at he juncture of the body portion of the blade and the pro ecting portion is provided, and failure of the machine lue to blade destruction is avoided.
While we have described a preferred embodiment of he invention, it will be understood the invention is not imited thereto since it may be otherwise embodied within he scope of the following claims.
1. Stator blade assembly comprising outer support neans having a plurality of radial openings extending herethrough, each of said openings having a differential liameter defining enlarged end portions one of which orms a locating shoulder; a plurality of stator blades ach including an airfoil body portion, and projections xtcnding from the ends of said body portion, said pro- :ctions comprising a tang section and an intermediate ection of varying width to form at least one shoulder hereon; a first attachment member fixedly secured to ach of said blades and including a body portion having it externally threaded surface and an opening extending hcrethrough for receiving a projection of said blade, said pening being formed to accommodate the intermediate ection of said projection, each of said blades being posiioncd in said support opening with the threaded surface -f its associated attachment member disposed within the nlarged end portion of the radial opening in said suport opposite that defining the locating shoulder; an
internally threaded fastening member threadably secured to said attachment member to releasably secure said blade to said support means: a second attachment member fixedly secured to the projection on said blade opposite that to which the first attachment member is secured, said second attachment member having an opening extending therethrough provided with a configuration of complementary to the configuration of the projection on said blade and an outer surface having an annular groove formed thereon; retainer means including two cooperating members each having an elevated central section for engagement with said groove on said second attachment memher, said retainer members being releasably connected to embrace the second attachment members.
2. In a fluid flow machine including stator blade support means having at least one opening formed therein; a stator blade including a body portion, a first end portion providing a first extension having a predetermined configuration including sections of varying width, and a second end portion providing a second extension having a configuration differing from the configuration of the first extension, a first attachment member having an externally threaded surface and an opening extending therethrough with the opening having a shape complementary to the shape of the first extension, assembled over the first extension and fixedly secured thereto, said first extension and permanently assembled attachment member projecting into the opening in said support; and an internally threaded fastening element detachably securing the blade and attachment member to the support.
3. In a fluid machine including stator blade support means having at least one opening formed therein; a stator blade including a body portion, a first end portion providing a first extension having a predetermined configuration including sections of varying width, and a second end portion, a first attachment member having an externally threaded surface and an opening extending therethrough with the opening having a shape com-plementary to the shape of the first extension, assembled over the first extension and fixedly secured thereto, said first extension and said permanently assembled attachment member projecting into the opening in said support; and an internally threaded fastening element detachably securing the blade and attachment member to the support.
3/1947 Great Britain.
5/1949 Great Britain.
EDGAR W. GEOGHEGAN. Primary Examiner. JULIUS E. WEST, Examiner.
E. A. POWELL, IR., Assistant Examiner.