EP1314856B1 - Device for locking blades in a disk groove - Google Patents

Description

The invention relates to a turbomachine wheel comprising a disk, vanes and a device for blocking vanes in the groove turbomachine disk device, said blades having hammer-type feet capable of being introduced into said groove through a loading window and held in said groove by form cooperation with the side walls of the latter, locking device being capable of being introduced into said groove by said loading window and having an element of locking arranged in the space separating two consecutive blades of dawn and capable of being reassembled in a lock housing provided in the side walls of said groove under the action of a maneuvering screw radial whose head is supported on the bottom of the groove, a radial clearance being provided between the bottom of the groove and the underside of the blade roots.

It can be provided several locking devices of this type per floor. In general, as illustrated in GB 2 156 908, the screw head which is wider than the cask in the bottom of the groove to the right of the corresponding lock housing. Because the screw head is wider than the barrel, the screw is returned captive. In current constructions, the locking element is consisting of a protrusion formed on the upper face of a body which is in the locking position of the device and bears against the walls side of the groove in the vicinity of the groove of the groove. This body has a lower base which, in the locking position of the device, is moved away from the screw head to allow sliding said body in the groove during assembly of the blades. Indeed for allow this sliding, the outgrowth formed on the body must be find in the groove, the base of the body is then in support on the head of screw and located near the bottom of the groove.

When the device is positioned next to the housing of latch, by rotating all the vanes around the disk, one move the body outwards by operating the maneuvering screw at means of a key fitting on the end of the screw opposite to the head and positioned in a hole in the platforms of both adjacent blades. The maintenance of the outgrowth in the housing of lock is made by bracing between, on the one hand, the lock body in the groove of the disc and, on the other hand, the screw head housed in an impression made at the bottom of the groove. The system works depending on the screw / nut type and is braked either by a local deformation or by an attached net, or by any other means.

If one loses the bracing effect, only the self-brake holds the screws and prevents the protrusion from escaping from the latch housing.

By construction, the one-piece piece constituted by the body and its outgrowth does not include positive guiding means when sliding in the groove during assembly. The screw head can therefore be improperly positioned in its footprint during tightening, which may result in a subsequent displacement of the screw head during the operation of the turbomachine and by a loss of the bracing effect. Tightening the incorrectly positioned screw may also cause seizure of the thread, which can ensure maintenance of the outgrowth in the lock slot, but what later causes difficulties to dismantle the device during maintenance operations.

In addition, when the turbomachine is in operation, the screw is subject to considerable centrifugal forces, which, if the bracing effect is lost, can cause a rotation of the screw coming out then in the gas vein, which, in the long run, can release the outgrowth of the latch housing when stopping the turbomachine.

In another known blocking device, the element of lock is axially slidably mounted in a radial opening of a body having a section adapted to the section of the groove and immobilized radially and the head of the screw is trapped between the bottom of the groove and the base of the body. Means are provided to limit the raising of the locking element.

Thus, the body is guided during its sliding in the groove, which ensures a precise radial direction of the axis of the screw and avoids seizures. In addition, the screw head is radially immobilized relative to the body, and the action of centrifugal forces on the element of when the screw is loosened partially, prevents the screw from turn, because the screw head is then in positive support against the base from the body. The body is placed between the feet of a pair of blades and has a section adapted to the section of said groove. It has a base lower located above the bottom of the groove and a radial opening through non-circular section in which the element of lock is slidably mounted under the action of the operating screw. The screw head is dimensioned so as to remain trapped between the bottom of the groove and the base of the body.

The body section in a plane perpendicular to the axis of the operating screw is greater than the section of the locking element in the same plane, and the section of the screw head is also greater than the section of the locking element so that the face top of the screw head can bear against the base of the body. This technology is therefore not suitable for certain turbine disks because of lack of space between the feet of two blades consecutive.

The object of the invention is to propose a turbomachine wheel comprising a locking device which overcomes this disadvantage and which can be housed in a reduced circumferential space.

This object is achieved according to the invention by the fact that the screw head is held radially outward by the two feet of dawn adjacent.

Thus, in case of loosening of the screw during operation, under the action of centrifugal forces, the outward movement of the screw is limited by the play between the bottom of the groove and the underside of the feet blade. When the screw head is in positive support against the dawn feet, the same centrifugal forces acting on the locking element push the latter outward, which prevents more tightening large of the screw and would even tend to turn it in the opposite direction.

According to a first simplified embodiment, the diameter of the screw head is greater than the distance between the two feet of dawn adjacent. The locking device then comprises two parts: the element lock and the maneuvering screw.

According to a second embodiment of the invention, a intermediate plate is interposed between the screw head and the locking, the ends of said plate being arranged under both dawn feet adjacent.

According to another advantageous characteristic of the invention, the plate has means for preventing its rotation relative to the locking element. These means consist for example of radial tabs that allow the rise of the element of lock during assembly.

Advantageously, the plate also comprises means to immobilize in rotation the screw head. These means consist of preferably by radial tabs pressing on the sides of the head quote. These tongues are flexible to allow rotation of the screw, during assembly, during the ascent of the locking element.

According to another characteristic of the invention, the element of locking has a greater protrusion in the vicinity of the end of the screw which is housed in the hole in the platforms two adjacent blades. This sleeve serves as a visual indicator of raising of the locking element.

• la figure 1 est une vue de dessus d'une partie de disque de roue non équipée d'aubes ;
• la figure 2 est une vue de dessus d'une partie de disque de roue équipée d'aubes à attache marteau immobilisées par un dispositif de verrouillage conforme à l'invention ;
• la figure 3 est une coupe selon la ligne III-III de la figure 2 d'un dispositif de blocage selon un premier mode de réalisation de l'invention, cette coupe étant prise selon un plan radial passant par l'axe de la turbomachine, les aubes n'étant pas montrées par souci de clarté ;
• la figure 4 est une vue axiale du dispositif de blocage entre deux pieds d'aube selon le premier mode de réalisation ;
• la figure 5 concerne également le premier mode de réalisation selon la ligne III-III, l'élément de verrouillage n'étant pas encore remonté ;
• les figure 6, 7 et 8 sont semblables respectivement aux figures 3, 4 et 5 et concernent un deuxième mode de réalisation de l'invention ;
• la figure 9 est une vue développée de la plaque en tôle utilisée dans le deuxième mode de réalisation ;
• la figure 10 est une coupe de la plaque intermédiaire selon la ligne X-X de la figure 11 ;
• la figure 11 est une vue de dessus de la plaque intermédiaire ; et
• la figure 12 est une vue de dessus de l'élément de verrouillage selon le deuxième mode de réalisation de l'invention.

Other advantages and characteristics of the invention will become apparent on reading the following description given by way of example and with reference to the appended drawings in which:

• Figure 1 is a top view of a wheel disc portion not equipped with blades;
• Figure 2 is a top view of a wheel disk portion equipped with hammer blade immobilized by a locking device according to the invention;
• FIG. 3 is a section along the line III-III of FIG. 2 of a locking device according to a first embodiment of the invention, this section being taken along a radial plane passing through the axis of the turbomachine, the blades are not shown for the sake of clarity;
• Figure 4 is an axial view of the locking device between two blade roots according to the first embodiment;
• Figure 5 also relates to the first embodiment according to line III-III, the locking element has not yet been reassembled;
• Figures 6, 7 and 8 are similar respectively to Figures 3, 4 and 5 and relate to a second embodiment of the invention;
• Figure 9 is a developed view of the sheet metal plate used in the second embodiment;
• Figure 10 is a section of the intermediate plate along line XX of Figure 11;
• Figure 11 is a top view of the intermediate plate; and
• Figure 12 is a top view of the locking element according to the second embodiment of the invention.

FIG. 3 shows in section a wheel disc 1 of turbomachine which has at its periphery a groove 2 for keep the dawn feet hammer tie type. This groove 2, delimited by lateral walls 3a and 3b of curvilinear section, opens to the outside by a groove 4 which has a dimension, in the direction of the axis of rotation of the wheel, smaller than the dimension of the cavity 5 formed in the bottom of the groove 2. The feet of the blades have a section according to the plan radial axis passing through the axis of rotation of the disc 1 adapted to the section of the groove 2 in order to be maintained by form cooperation.

Figure 1 is a top view of a portion of the disc 1. As seen in this figure 1, the side walls 3a and 3b have vis-à-vis a first pair of radial notches 6a and 6b which constitute a loading window, allowing the introduction feet 7 of the blades 8 in the groove 2 during assembly of these blades 8, as well as a second pair of radial indentations 9a, 9b which constitute a housing for the lock of an object blade locking device of the invention. The second pair of indentations 9a, 9b is offset angularly with respect to the first pair of notches 6a, 6b of a distance equal to the angle formed by two consecutive blades or multiple of this angle. It should be noted that the same wheel disc 1 can comprise several locking devices according to the invention.

Figure 2 shows the same part of disk 1 equipped with its 8. Each blade 8 has between its foot 7 and its aerodynamic portion 10, a platform 11 which covers the periphery of the disk 1, all of the platforms 11 of the vanes 8 defining internally the vein of the gas stream.

For mounting the blades 8 on the disc 1, we proceed from the same way. We successively introduce the foot 7 of each blade 8 in the groove 2 by the window constituted by the first pair notches 6a, 6b and the blade 8 is slid in the direction of the arrow F until his platform 11 comes up against the platform of Dawn previously introduced.

All the blades 8 are identical except for the penultimate climb, referenced 8a, and the last climb, referenced 8b, which have on the adjacent edges of their platforms 11a and 11b notches 12a and 12b which constitute an orifice 13 whose function will be explained later in this memo.

After the introduction of penultimate dawn 8a in the groove 2, a locking device 14 is inserted through the window of loading in the groove 2, then we position the foot 7 of the last dawn in the loading window between the last dawn climb 8a and the first dawn mounted and we slide all of all blades 8 in the direction and the arrow F, an angle corresponding to the half-measure the angle between two consecutive blades, so that the platforms 11a and 11b of the first dawn mounted 8a and the last dawn climb 8b are joined according to the median plane and the window of loading constituted by the first pair of notches 6a and 6b. In this position, the locking device 14 disposed between the feet 7 of the blades 8a and 8b is opposite the second pair of indentations 9a and 9b.

The indentations 9a and 9b have axial dimensions and lower than those of the indentations 6a and 6b of the window of loading blades 8, to prevent the vanes from escaping 8 when they pass in front of these indentations 9a and 9b.

It should be noted that there is a game between the bottom 15 feet 7 blades and the bottom of the groove 2.

Figures 3 to 5 show a first embodiment of the locking device 14 which consists of two pieces, namely a locking element 16 and an operating screw 17.

The locking element 16 has a section, in a radial plane passing through the axis of rotation of disk 1, which is drawn from way that the locking element 16 can slide in the groove 2 during assembly. It has a radial tapping equipped with a thread 31 intended to cooperate with the thread of the barrel 40 of the operating screw 17. The operating screw 17 comprises a screw head 41 of large size which lodges in the annular space 21 delimited by the underside 15 of the feet 7 and the bottom of the groove 2. The diameter of this head 41 is greater than the distance between the two blade roots 7a and 7b adjacent to them, as shown in Figure 4. The peripheral part of the upper face 42 of the screw head 41 can therefore bear against the underside 15 of these two blade roots 7a and 7b, which limits the possible radial displacement of the screw head 41. The end 43 of the screw 17, opposite to the screw head, housed in the hole 13 formed by the notches 12a and 12b of the platforms 11a and 11b. This end 43 is provided with means cooperating with a clamping wrench of the type "Allen" for example, in order to be able to reassemble the locking element 16 radially outward when positioned in front of the second pair of indentations 9a and 9b.

The circumferential dimension of the indentations 9a and 9b is advantageously less than the distance separating the two feet of dawn consecutive 7a and 7b. The circumferential dimension of the base 23 of the locking element 16 is substantially equal to or less than the distance between the two adjacent blade roots 7a and 7b, while the circumferential dimension of the upper part of the element of locking is substantially equal to the circumferential dimension of notches 9a and 9b, at least in the zones 22a, 22b which are to house in these indentations 9a and 9b, after the rise of the element of lock 16.

As shown in FIG. 5, the zones 22a and 22b are arranged in the cavity 5 of the groove 2, when the element of lock is in the lowered position. It is the same with the base 23 of the locking element 16, whose lower face 24 is then at little distance above the upper face 42 of the screw head.

When the locking element 16 is wound up by rotation of the operating screw 17, as shown in FIG. 3, the lower face 24 of the locking element 16 is remote from the head quote. The side walls 25a and 25b of the base 23 are then supported against the side walls 3a and 3b of the groove 2 in the vicinity of notches 9a and 9b.

During the operation of the turbomachine, the forces centrifugal forces exerted on the locking element 16 tend to push the latter and the maneuvering screw outwards. The side walls 25a and 25b of the base 23 are then in positive support against the side walls 3a and 3b of the groove 2, and in case of loosening of the operating screw 17, the displacement of the screw head 41 will be limited because the peripheral portion of the screw head 17 is retained by the adjacent blade roots 7a and 7b. When disc 1 is stopped, the head of screw 17 may rest on the bottom of the groove 2, but the portions 22a and 22b of the locking element 16 will remain trapped in the notches 9a and 9b.

References 26a and 26b designate radial protuberances, parallel to the axis of the operating screw 17, which extends radially outward above the top of the element of 16, and whose vertices are arranged in the hole 13 of the platforms 11a and 11b, when the locking element 16 is reassembled, to serve as a visual witness of the good recovery of the locking element 16, during assembly, or during the visits maintenance.

The first embodiment of the invention described above requires that the diameter of the screw head 41 is greater than the spacing between the two adjacent blade roots 7a and 7b. This requires that the axial dimension of the underside 15 of a blade root is greater than the distance separating the two adjacent blade roots 7a and 7b.

Figures 6 to 12 show a second embodiment of the invention which can be applied to any type of blisk of the type hammer attachment.

In the second embodiment of the invention, the element 16 is almost identical to the one described above and will not be not described further. Only optional variants will be described.

The operating screw 17, according to the second embodiment of the invention, has a screw head 41, of small diameter and non-circular preference. This diameter is for example less than the distance separating the two adjacent blade roots 7a and 7b.

To limit the possible radial displacement of the screw head 41, an intermediate plate 50 is interposed between the screw head 41 and the locking element 16. This intermediate plate 50, which has a oblong shape, has a central orifice 51 through which the barrel 40 of the operating screw 17, and its circumferential dimension is such that its ends 52a and 52b are disposed under the two feet of dawn adjacent 7a and 7b.

Thus, in case of loosening of the screw during operation of the turbomachine, the upper face 42 of the screw head 17 bears on the underside of the intermediate plate 50, of which the ends 52a and 52b bear on the undersides 15 of the two adjacent dawn feet, which limits the radial displacement of the head of screw 41.

Advantageously, the intermediate plate 50, which is made preferably from a sheet metal by cutting and folding, and which is shown in detail in FIGS. 9 to 11, comprises two radial tabs 53a and 53b that extend outward and that fit in radial grooves 54a and 54b formed on two opposite sides of the element of 16, as shown in Figure 12. The cooperation tongues 53a and 53b with grooves 54a and 54b prevents the plate intermediate 50 to rotate relative to the locking member 16, while permitting the sliding of the locking element 16 by relative to the intermediate plate 50, during the ascent or descent of the locking element. The grooves 54a and 54b are preferably on the face s of the locking element 16 which are opposite the faces adjacent to the two blade roots 7a and 7b.

The intermediate plate 50 also includes and preferably two elastic tabs 55a and 55b which extend radially inward and intended to prevent loosening of the operating screw 17, the head 41 of the latter then comprising sections, six in number for example, on which the tabs 55a and 55b are in support.

The elasticity of the tabs 55a and 55b is calculated so as to allow the rotation of the screw head 17 when a couple is exercised predetermined on the end 43 of the operating screw 17, during the raising or lowering of the locking element 16, and is sufficient to prevent the rotation of the screw head 17 in the absence of this torque.

FIG. 9 shows the development of the intermediate plate 50, before folding tabs 53a, 53b, 55a and 55b. We note that the orifice 51 is not circular.

The centering of the intermediate plate 50 with respect to the screw maneuver 17 is achieved by the cooperation of the tongues 53a and 53b with the grooves 54a and 54b of the locking member 16. The orifice 51 however, it is dimensioned in such a way that the screw head 41 is bearing against the lower face 55 of the intermediate plate 50.

It should be noted that the locking element 16 according to the first embodiment of the invention does not need radial grooves 54a and 54b described above, which serve to prevent rotation of the plate intermediate 50.

However, the same type of locking element having radial grooves 54a and 54b can be used in both modes of embodiment of the invention. Only the geometry of the space hosting the head 41 is to be considered to make the choice of the embodiment preferred embodiment of the invention.

Claims (9)

1. Turbomachine wheel comprising a disc (1), blades (8) and a device (14) for immobilizing the blades, the said disc comprising a peripheral groove (2), the said blades comprising roots (7) of the hammerhead type which can be introduced into the said groove (2) through a loading window (6a, 6b) and held in the said groove (2) by collaboration of shape with the side walls (3a, 3b) of the latter, the said immobilizing device being able to be introduced into the said groove through the said loading window and comprising a locking element (16) arranged in a space separating two consecutive blade roots (7a, 7b) and able to be raised into a lock housing formed in the side walls of the said groove through the action of a radial operating screw (17), the head (41) of which rests against the bottom of the groove, a radial clearance being provided between the bottom of the groove (2) and the underside (15) of the blade roots, characterized in that the screw head (41) is retained radially outwardly by the two adjacent blade roots (7a, 7b).
2. Turbomachine wheel according to Claim 1, characterized in that the diameter of the screw head (41) is greater than the separation between the said two blade roots (7a, 7b).
3. Turbomachine wheel according to Claim 1, characterized in that an intermediate plate (50) is interposed between the screw head (17) and the locking element (16), the ends (52a, 52b) of the said plate (50) being arranged under the said two adjacent blade roots (7a, 7b).
4. Turbomachine wheel according to Claim 3, characterized in that the plate (50) comprises means for preventing it from turning with respect to the locking element (16).
5. Turbomachine wheel according to Claim 4, characterized in that the said means consist of radial tabs (53a, 53b).
6. Turbomachine wheel according to any one of Claims 3 to 5, characterized in that the plate comprises means for stopping the screw head (41) from turning.
7. Turbomachine wheel according to Claim 6, characterized in that the said means for stopping the screw head from turning comprise radial tabs (55a, 55b) bearing against flats of the screw head (41).
8. Turbomachine wheel according to any one of Claims 3 to 7, characterized in that the said plate is made of sheet metal.
9. Turbomachine wheel according to any one of Claims 1 to 8, characterized in that the locking element has at least one upper protuberance (26a, 26b) in the vicinity of the end of the screw, this protuberance becoming housed in an orifice (13) formed in the platforms (11a, 11b) of the two adjacent blades (8a, 8b) and serving as a visual indicator of the raising of the locking element (16).

Images