US3501247A - Blade fixing arrangement - Google Patents

Description

March 17, 1970 M. J. ToURNERE BLADE FIXING ARRANGEMENT Filed July 5. 1968 Zb Za United States Patent Office 3,501,247 BLADE FIXING ARRANGEMENT Marcel Joseph Tournere, Paris, France, assignor to Societe Nationale dEtude et de Construction de Moteurs dAviation, Paris, France, a company of France Filed July 5, 1968, Ser. No. 742,658 Claims priority, application France, July 7, 1967,

Int. Cl. F01d 9/02 U.S. Cl. 415--189 5 Claims ABSTRACT OF THE DISCLOSURE A device for fixing a set of blades to the wall of a turbine, openings being provided in said wall to permit the individual introduction or extraction of the blades, said device comprising mounting inserts which close ofi the spaces formed between the blade roots and the peripheries of the openings, and a keeper which locks together the blades, the mounting inserts and the wall.

This invention relates to the fixing of at least one set of blades, each of said blades having a root portion, to a wall delimiting an annular duct through which the working fluid of a machine, such as a compressor or a turbine, is to fiow, and relates more particularly to an arrangement of the kind comprising, in said wall, a number of openings equal to the number of blades and intended on the one hand to enable the individual introduction of said blades into said duct in a direction transversely thereof (as well as the individual extraction of said blades therefrom), and on the other hand to locate the root portions of said blades.

The invention applies in particular, but not exclusively, to the attachment of blades at their external extremities to a casing surrounding a rotor of the machine. The casing may be xed and constitute, along with the blading which it carries, a stator of the machine. Equally, however, it may be a moving component and thus may constitute an external rotor rotating in the opposite direction to an internal rotor, i.e. as inthe well-known technique of contra-rotating rotors.

The usual blade fixing methods generally mean that, in order to replace a single defective blade, dismantling and reassembling is required of the whole of the blading set to which said single blade belongs. These are difiicult, lengthy and consequently costly operations and, in the case of contra-rotating turbines, the job-time is further increased because it is necessary to dismantle a fixed casing which in this instance surrounds the rotating casing.

It is the object of the invention to achieve a method of fixing by which it is possible in an economical manner to dismantle and reassemble a single blade rapidly, without any need to remove from the body of the machine the whole of the blading set in which the particular blade is located. The invention applies to ordinary compressors and turbines, but is especially valuable in bladed machines having contra-rotating rotors.

According to the invention, in a blade fixing arrangement of the kind set forth, each of the blade roots and the surrounding openings in the wall are dimensioned so that a gap is left therebetween which is adapted to be closed ofi by a mounting insert for each blade which is slidable thereover, there being provided in common to the blades of one set a locking device for locking together the blades, the mounting inserts and the wall, which device permits the selective unlocking of any blade in the said set whilst the others are held locked.

In accordance with an advantageous embodiment of the invention, the device for locking together the iblades of the said set comprises a keeper adapted to slide through 3,501,247 Patented Mar. 17, 1970 passages formed through extensions of the blades and of the mounting inserts in the set, said passages being aligned, in the assembled position, with a groove formed in the wall, and the two extremities of the said keeper having between them, in the assembled position, a peripheral interval at least equivalent to the Width of one of the openings through which the blades are introduced. The keeper may then be fixedly located in relation to the casing by means of a detachable key or the like passing through the gap between the two keeper extremities.

It will be seen that the release of a blade can be effected in a very simple way. All that is necessary is to remove the key and then slide round the keeper until its two extremities embrace the mounting insert of the blade which is to be dismantled.

The description which now follows in relation to the accompanying drawing will indicate by way of a nonlimitative example how the invention may be put into effect,

In the drawing:

FIGURE 1 schematically illustrates, in longitudinal half-section, a compressor having blades adapted to be fixed by means of an arrangement in accordance with the invention;

FIGURE 2 is a partial, longitudinal half-section, on the line II-II of FIGURE 3, through the external casing of a compressor, showing one embodiment of the arrangement for fixing a blade to the casing in accordance with the invention;

FIGURE 3 is a partial, transverse half-section, on the line III-III of FIGURE 2, through the casing and the blades it carries;

FIGURE 4 is a partial, peripheral View, from the exterior, of the casing and the blades it carries;

FIGURE 5 is a schematic pictorial view of part of the casing;

FIGURE 6 is a schematic pictorial View of an intermediate component (mounting insert) associated with each of the blades and assisting in its fixing; and

FIGURE 7 is a schematic pictorial view of one of the blades intended for fixing to the casing.

FIGURE 1 schematically illustrates a machine, in the selected example an axial iiow compressor of the contrarotating type, with an external rotor and an internal rotor, having an annular duct delimited by at least one wall, through which a working fiuid liows. The external rotor comprises in particular the wall 1 which, in the example shown, constitutes an external casing carrying blades 2, fixed at their other ends to discs 3 located coaxially relative to the axis X-X of the machine. Means (not shown) are provided in order to drive this rotor. The internal rotor carries blades 4 mounted on discs 5 fixed to a drive shaft 6.

One embodiment of the invention which will now be described in relation to FIGURES 2 to 7, relates more particularly to the fixing of the blades 2 to the wall 1. In the selected example, which corresponds to a preferred application, this wall is itself movable but it is obvious that the invention could equally well be applied to conventional machines not having contra-rotating rotors, the reference 1 in such case indicating the stator casing of the machine.

The Wall 1 (contra-rotating or fixed) carries, at its periphery, a number of circular grooves 1c equal in number to the number of blading rings or blading sets, said grooves being formed in shoulders 1b. One of these shoulders and its corresponding groove are clearly visible in FIGURE 5. At intervals, the groove and shoulder are interrupted by substantially oblong openings 1a made in the casing 1. It will be seen that the two parts of the shoulder, located at either side of the groove, contain a hole 1d, the purpose of which will be explained hereinafter.

The blades 2 each comprise a root 2a above which there projects a shoulder 2b; the latter is traversed by a passage 2c which can be seen particularly clearly in FIG- URE 7.

Each of the blades 2 is associated with an intermediate component 7, or mounting insert, by means of which, in a manner to be explained later, it is fixed to the casing, Said mounting insert being shown separately in FIG- URE 6.

The mounting insert 7 is for this purpose provided with a substantially oblong base 7a adapted to fit in the opening 1a and flanked peripherally by a flange 7e fwhich serves to locate the insert in a corresponding countersink 1e formed in the casing around the opening 1a. The base 7a is pierced by an opening 7d whose dimensions correspond to those of the root 2a of the blade, and carries two cheeks 7b located at either side of the opening. The cheeks themselves contain holes 7c.

In the assembled position, shown in FIGURES 2, 3, and 4, the intermediate component or mounting insert 7 is inserted into the substantially oblong opening 1a, the fiange 7e abutting against the undercut 1e in the casing, and the blade 2 is fitted with its root portion 2a into the opening 7d in the insert so that its shoulder 2b is located between the cheeks 7b of the insert. The circular groove 1c in the casing, the passages 2c in the blades and the holes 7c in the insert, are now all aligned.

A keeper 8 can now be inserted through the aligned passage system 1c, 2c, 7c thus defined. The purpose of this keeper is simply to lock the set of blades. In the case that the machine is of the contra-rotating type, the expansion forces due to centrifugal action are taken, not by the keeper 8, but by the disc 3 to the periphery of which the blades are fixed in a known manner, for example by the conventional fir-tree formation 2d shown in FIGURES 2 and 3.

The keeper 8 does not have its extremities Srl-8b flush with one another; as FIGURES 3 and 4 show, there is a free space between these ends, the width e of 'which is slightly greater than the width e1 of a mounting insert 7.

In order to lock the set of blades, the keeper is slid circumferentiaily until its two extremities 8a, 8b, are l0- cated at either side of the hole 1d lvisible in FIGURES 3, 4 and 5. Then, there is inserted into the hole a locking device 9 (See FIGURE 5) of some kind, such as a pin, screw or key etc., in order to prevent any further circumferential movement of the keeper.

In order to replace a blade, the procedure is as follows: the first operation is to remove the locking device 9 in order to release the keeper 8. Then, the keeper is slid around until its two extremities 8a, 8b occupy the position shown in FIGURES 3 and 4 in which they surround the mounting insert 7 of the blade 2 which is to be dismantled. This mounting insert being thus unlocked, it can be moved radially towards the axis of the machine, to bring it into a position shown in broken line in FIG- URES 2 and 3.

Then, the formation 2d of the blade is disengaged axially from the disc 3, giving the mounting insert 7 this same axial movement. The blade root then passes through the substantially oblong opening 1a in the casing. As FIGURE 2 shows, this axial disengagement is rendered possible by appropriately dimensioning the mounting inserts so that the distance l, separating the edge of the opening 7d from the front or rear edge of the base 7a of the insert, is greater than the width l1 of the formation 2d by which the blade is fixed to the dise 3.

Finally, the blade 2 is removed radially outside through the opening 7d in the insert and the substantially oblong opening 1a in the casing. Obviously, for this to be possible the width IJ, of the opening 791 must be greater (as 4 FIGURE 3 indicates) than the width b1 of the blade formation 2d.

When this has been done, a replacement blade can be inserted by carrying out the operations, outlined hereinbefore, in the reverse order.

I claim:

1. In a machine having at least one bladed component consisting of a wall carrying at least one set of blades, wherein the root of each blade of the set is detachably fixed in an opening in the said wall, the improvement wherein the blade roots and their associated openings in the -wall are mutually sized so that gaps are left surroundingsaid blade roots received in said wall openings, and wherein a fixing arrangement is provided comprising:

a plurality of inserts, one for each blade, adapted to close the said gaps around the blade roots with the blade roots extending slidably therethrough;

a keeper common to the blades of the one set and adapted to hold in fixed relationship the blades, the inserts and the wall, said keeper being movable to permit release of any blade of the set from the wall said keeper being movable to permit release of any blade of the set from the wall while maintaining its hold'on the remaining blades of the set;

and releasable means for locking said keeper in the position in which all the lblades are fixed.

2. A machine according to claim 1, wherein the keeper is adapted to slide through passages formed in extensions of the blades and of the mounting inserts in one and the same set, said passages being aligned, in the assembled position, with a groove formed in the wall, the two extremities of said keeper, in the assembled position, having a gap between them whose width is at least equal to the width of the openings through which the blades are introduced.

3. A machine according to claim 2, wherein the releasable means for the keeper comprises means for iixedly locating the keeper in relation to the wall.

4. A machine according to claim 3, wherein the locating means is constituted by a detachable key adapted to occupy the gap left between the two extremities of the said keeper.

5. A machine having at least one bladed component consisting of a wall carrying at least one set of blades, wherein the root of each blade of the set is detachably fixed in an opening in the said wall, the blade roots and their associated openings in the wall being mutually sized so that gaps are left surrounding said blade roots when these are received in the said wall openings, and the xing of the blades lbeing completed by a fixing arrangement which comprises a plurality of inserts, one for each blade, adapted to close the said gaps around the blade roots with the blade roots extending slidably therethrough, and a locking device, common to the blades of the one set, for locking together the blades, the inserts and the wall, said locking device being adapted to permit selective unlocking of any blade of the set while the others are held locked.

References Cited UNITED STATES PATENTS 764,451 7/ 1904 Geisenhner. 1,720,754 7/1929 Baumann.

FOREIGN PATENTS 267,405 3/ 1927 Great Britain. 281,032 12/1927 Great Britain. 599,391 3/ 1948 Great Britain.

E-VERETTE A. POWELL, IR., Primary Examinep US. Cl. XR.

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