EP1760259B1 - Locking apparatus for an axial retention ring of a blade - Google Patents

Description

TECHNICAL AREA

The present invention relates to the technical field of rings for axial retention of the blades of a rotor of a turbomachine, in particular an aircraft engine.

It is a device for immobilizing in rotation of such a retention ring.

It also relates to a rotor comprising such a device for immobilizing rotation.

Finally, it relates to a turbomachine, for example an aircraft engine, equipped with such a device for immobilizing rotation.

Throughout the text, the term "axial" refers to the axial direction of the turbomachine.

STATE OF THE PRIOR ART

It is known that a turbomachine rotor is equipped with a disk and vanes carried by the disk, as well as with a retention ring to prevent movement of the vanes in the axial direction, as described in the document FR 2 729 709-A1 .

The figure 1 illustrates such a blade retention ring of a rotor, known from the prior art.

Referring to the figure 1 a disk 10 of a rotor has a disk body 11 and teeth 12 which extend radially from the disk body 11 and are distributed over the circumference thereof. The space between two successive teeth 12 forms a cell 13 oriented axially. Each tooth 12 is provided with at least one hook 6 projecting in an axial direction, which defines on this tooth an elementary groove opening radially inwards. In the illustrated example, the teeth 12 are provided with an upstream hook 6 and a downstream hook 6.

The figure 2 illustrates a foot 14 of a blade 16 inserted in such a cell 13. The two teeth 12 can contain circumferentially and radially this blade 16.

As illustrated on the figure 2 , and in known manner, a retention ring 20 is placed in a groove 22, discontinuous, which corresponds to the succession of elementary grooves. The presence of the retaining ring 20 in the groove 22 makes it possible to prevent axial displacement of the blades 16. To facilitate its installation in the groove 22, the retaining ring 20 is opened by a slot 24 which separates the two ends or strands 26 thereof.

It is generally preferred that the slot 24 of the retaining ring 20 is located at one of the teeth 12 and not between two adjacent teeth 12, in order to prevent the ends of the retention ring 20 from coming out. of the groove 22. For this purpose, it is known to provide the retaining ring 20 with a device for immobilizing rotation, which ensures that the slot 24 remains positioned at the level of one tooth 12 once the retention ring 20 has been installed in the groove 22.

• deux taquets 30 de l'anneau de rétention 20, qui sont disposés respectivement aux deux extrémités 26 de celui-ci, de chaque côté de la fente 24, et qui ont chacun une face de contact 32 du côté de la fente 24, et
• un crochet formant butée 60 de l'une des dents 12, ce crochet formant butée 60 ayant une face frontale 42 et deux faces latérales 44 sensiblement opposées l'une à l'autre, les faces latérales 44 étant obtenues par usinage des côtés latéraux du crochet formant butée 60.

The immobilization device in rotation of the retention ring 20 according to the prior art, illustrated in FIG. figure 1 , includes:

• two tabs 30 of the retaining ring 20, which are respectively disposed at both ends 26 thereof, on each side of the slot 24, and which each have a contact face 32 on the side of the slot 24, and
• a hook forming a stop 60 of one of the teeth 12, this stop-forming hook 60 having a front face 42 and two lateral faces 44 substantially opposite to each other, the lateral faces 44 being obtained by machining the lateral sides of the hook forming a stop 60.

When the retaining ring 20 is put in place in the groove 22, each contact face 32 of the respective cleats 30 is in abutment against one of the lateral faces 44 of the abutment hook 60. As a result, the slot 24 becomes is located under the stopper hook 60 and the retaining ring 20 is prevented from rotating in the groove 22, so that the retaining ring 20 can not spontaneously exit the groove 22 during operation of the turbomachine. It follows that the vanes 16 can not escape from the cells 13 into which their feet 14 are inserted.

However, the width D of the stopper hook 60 is reduced, because of the machining of this stopper hook 60 on its two lateral sides. As a result the overlap of the slot 24 of the retaining ring 20 by the stopper hook 60 is a distance which is equal to the width D of the hook stop 60, and there is a risk that one of the two ends 26, or both ends 26, of the retaining ring 20 escapes from the elementary groove of the tooth 12 having the stopper hook 60. This risk is increased when the slot 24 of the retaining ring 20 is oriented obliquely to the circumferential direction of the retaining ring 20, and not perpendicular to this direction. As a result, there could be an axial displacement of a blade 14, and consequently the loss of this blade 14.

STATEMENT OF THE INVENTION

The present invention provides a device for immobilizing in rotation a retaining ring of the blades of a rotor of a turbomachine, which overcomes the disadvantage mentioned above inherent to the rotation immobilization device of the prior art.

According to a first aspect, the invention relates to an immobilization device in rotation of a blade retention ring on a rotor disk of a turbomachine in a substantially axial direction of said turbomachine,
said rotor disk being provided with hooks distributed over its circumference and defining a groove for receiving said retention ring, including a first immobilizing hook, a second immobilizing hook and a third hook; successive immobilization means, said second immobilization hook being located between said first and third immobilizing hooks, and said retaining ring being provided with a slot, and two cleats disposed on one side thereof on each side of said slot. According to the invention, the position of said catches on said retaining ring is such that, when said retention ring is in place in said groove, said two catches abut respectively against said first immobilization hook and against said third catcher hook. immobilization, and said slot is covered by said second immobilization hook.

As will become apparent in the remainder of the description, the expression "immobilization hook" covers two functions that are fulfilled by one and / or more of these three hooks: a stop function for a stop and a recovery function of the slot.

Preferably, said first and said third immobilization hooks each have a locking face on their side which is opposite to the opposite side of said second immobilizing hook, said stops of said retention ring are each provided with a contact face oriented towards said slot, and said locking faces cooperate with said contact faces for an abutment of said tabs against said first and third locking hooks.

In particular, said groove has two walls, an inner wall closest to the disc of rotor and an outer wall farthest from the rotor disc, and each locking face is located on the corresponding immobilizing hook, and extends in the axial direction from the free surface of said immobilizing hook to the inner wall of said groove.

According to an alternative embodiment, said locking faces are oriented in a radial plane of said rotor disk.

According to another variant embodiment, said locking faces are oriented in an oblique plane with respect to a radial plane of said rotor disk.

According to a second aspect which is not claimed, the invention relates to a disk / ring assembly,
having a retaining ring provided with a slot, and having a rotor disk provided with hooks distributed over its circumference and defining a groove for receiving said retaining ring,
characterized in that said rotor disk includes a first immobilization hook, a second immobilization hook and a third successive immobilization hook,
in that said retention ring has two tabs disposed on one side thereof on each side of said slot,
and in that the position of said catches on said retention ring is such that, when said retention ring is in place in said groove, said two catches abut against said first hook respectively. immobilization and against said third immobilization hook, and said slot is covered by said second immobilization hook.

Preferably, said first and said third immobilization hooks each have a locking face on their side which is opposite to the opposite side of said second immobilizing hook, said stops of said retention ring are each provided with a contact face oriented towards said slot, and said locking faces cooperate with said contact faces for an abutment of said tabs against said first and third locking hooks.

According to a third aspect, the invention relates to a turbomachine rotor comprising an immobilizer according to the first aspect of the invention and / or a disk / ring assembly according to the second aspect of the invention.

According to a fourth aspect, the invention relates to a turbomachine, for example an aircraft engine, comprising an immobilizer according to the first aspect of the invention and / or a disk / ring assembly according to the second aspect of the invention. 'invention.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1, déjà décrite, représente une vue en perspective d'une portion de disque de rotor, adapté pour un dispositif d'immobilisation en rotation d'un anneau de rétention d'aubes, conformément à la technique antérieure ;
• la figure 2, déjà décrite, représente une vue en perspective d'un dispositif d'immobilisation en rotation d'un anneau de rétention d'aubes d'un rotor de turbomachine, conformément à la technique antérieure ;
• la figure 3 représente une vue en perspective d'une portion de disque de rotor, adapté pour un dispositif d'immobilisation en rotation d'un anneau de rétention d'aubes mobiles, conformément à l'invention ;
• la figure 4 représente une vue en perspective d'un dispositif d'immobilisation en rotation d'un anneau de rétention d'aubes d'un rotor de turbomachine, conformément à l'invention.

The invention will be better understood on reading the following detailed description of embodiments of the invention, given by way of illustration and in no way limiting, with reference to the appended drawings, in which:

• the figure 1 , already described, shows a perspective view of a rotor disk portion, adapted for a device for immobilizing in rotation a blade retention ring, according to the prior art;
• the figure 2 , already described, represents a perspective view of an immobilization device in rotation of a blade retention ring of a turbomachine rotor, according to the prior art;
• the figure 3 is a perspective view of a rotor disk portion adapted for a rotational immobilization device of a blade retention ring according to the invention;
• the figure 4 represents a perspective view of an immobilization device in rotation of a blade retention ring of a turbomachine rotor, according to the invention.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

The immobilization device in rotation according to the invention, illustrated in FIGS. Figures 3 and 4 , will only be described for its differences with the rotation immobilization device according to the prior art, illustrated in FIGS. Figures 1 and 2 . In the figures, identical references designate identical characteristics.

To simplify the detailed description that follows, the retention ring will simply be called "ring" and the first, second and third immobilization hooks will simply be called "First hook", "second hook", and "third hook" respectively.

Referring to Figures 3 and 4 a disk 10 of a rotor has teeth 12 which extend radially from its circumference and are distributed over this circumference. The space between two successive teeth 12 forms an axially oriented cell 13 in which is inserted a foot 14 of a blade 16. These two successive teeth 12 have shapes and dimensions that can contain circumferentially and radially the blade 16 installed between them in cell 13.

The teeth 12 have a protruding portion 4 protruding from the disc 10 in the upstream axial direction, and / or a protruding portion 4 protruding from the disc 10 in the axial downstream direction. In each projecting portion 4 is formed an elementary groove opening radially inwards, the free end of each projecting portion 4 beyond the elementary groove with respect to the disk body 11 forming a hook 6 oriented radially. towards the inside. Each elementary groove has two walls, an inner wall closest to the rotor disk 10 and an outer wall furthest from the rotor disk 10.

The succession of elementary grooves forms a groove 22, discontinuous, in which is disposed a ring 20. The ring 20 in the groove 22 constitutes an axial abutment which makes it possible to prevent axial displacement of the blades 16. To facilitate its installation in the groove 22, this ring 20 is open by a slot 24 which separates its two ends 26 from one another.

The ring 20 comprises two cleats 30 positioned on the same face thereof, on the face opposite its face facing the rotor disk 10, in the example illustrated in FIG. figure 2 .

Preferably, each cleat 302, 304 is made in the following manner. Two cuts are made on the ring 20, so as to remove a ring sector having a given dimension in the circumferential direction of said ring 20 and the same dimension as the rest of the ring 20 in the axial direction thereof . The removed sector is replaced by a part having the same dimension in the axial direction and the same dimension in the circumferential direction, but having a greater thickness. This piece is fixed to the rest of the ring 20 by welding so as to reconstitute a closed ring 20. Then the cleat 302, 304 is machined in said piece of greater thickness than the remainder of the ring 20. Such a procedure allows precise machining of the cleats 302, 304, ensuring their dimensions and their position on the ring 20.

The slot 24 is made on the ring 20 after the two tabs 30 are made. It is positioned in such a way that the two catches 30 are arranged towards one of the ends 26 of the ring 20, on either side of the slot 24 at a determined distance therefrom. Preferably, the two tabs 30 are spaced apart from one another angular at least equal to three times the angular pitch of the blades 16. This angular pitch is defined as the angular difference between the median planes of two successive cells 13.

Each tab 30 has a contact face 32 oriented towards the slot 24 of the ring 20.

Among the hooks 6 are successively a first hook 62, a second hook 64 and a third hook 66.

The second hook 64 has a geometry similar to the geometry of the hooks 6 of the prior art.

The first hook 62 and the third hook 66 have a modified geometry with respect to the hooks 6. Each of the first and third hooks 62, 66 has a front face 142 which is the face of its free surface, and a side face 144 which is substantially perpendicular to the end face 142. The lateral face 144 of the first hook 62, respectively of the third hook 66, extends from the front face 142 of said hook 62, 66, to the inner wall of the elementary groove of said hook 62. , 66. Preferably, the lateral face 144 of the first hook 62 is obtained by machining, on its lateral side which is opposed to its lateral side which is opposite the third hook 66. Similarly, the lateral face 144 of the third hook 66 is obtained by machining on its lateral side which is opposed to its lateral side which is opposite the first hook 62.

In other words, each of the corresponding teeth 12 terminates in a hook 62, 66 which has a lateral face 144 on its side opposite its opposite side of the other hook 66, 62, said lateral face 144 being circumferentially withdrawal.

In the example shown in figure 2 the side faces 144 are oriented in a radial plane of the rotor disc 10.

The position of the two catches 30 on the ring 20 is suitably set, preferably according to the dimensions and distances of the hooks 62, 64, 66 of the rotor disk 10. This position can be defined by their respective distances from the respective ends of the ring 20 or the angular gap between them. For reasons of ease of manufacture, it is preferred, but not necessary, that the two tabs 30 are arranged symmetrically on either side of the slot 24.

With an appropriate relative position of the two catches 30 on the ring 20, when the ring 20 is put in place in the groove 22, the contact face 32 of one of the catches 30 is in abutment against the lateral face 144. of the first hook 62, and the contact face 32 of the other dog 30 is in abutment against the lateral face 144 of the third hook 66. The lateral faces 144 are respective locking faces of the first hook 62 and the third hook 66 , which cooperate with the respective contact faces 32 of the two cleats 30 of the ring 20. two ends 26 of the ring 20 and the slot 24 are then under the second hook 64.

The ring 20 is thus prevented from rotating in the groove 22. As a result, the ring 20 can not escape from the groove 22 during operation of the turbomachine. It follows that the vanes 16 can not escape in the axial direction of the cell 13 in which they are inserted.

The invention which has just been described thus makes it possible to prevent the ring 20 from rotating in the groove 22. It has the advantage that the slot 24 of the ring 20 is positioned under a hook and not between two hooks. In addition, the slot 24 is positioned under the second hook 64, which has no recessed side face, and therefore has a width DD which is not reduced as could be the width D of the hook 60 of the device immobilization of the prior art. As a result, the risks of exit of the ends of the ring 20 out of the groove 22 are reduced.

With the immobilization device in rotation of the ring according to the invention, the actual immobilization function (by abutting the contact faces 32 of the catches against the locking faces 144 of the first and third hooks 62, 66 ) and the overlap function of the slot 24 is not provided by a single disk hook as was the case with the immobilizer of the prior art.

The invention is not limited to the embodiment which has just been described. On the example illustrated at figure 4 , the slot 24 is perpendicular to the circumferential direction of the ring 20, but it could be oblique, without departing from the scope of the invention.

In the example illustrated in Figures 3 and 4 , the locking faces are oriented in a radial direction of the rotor disc 10, but they could be oriented in a direction oblique to a radial direction of the rotor disc 10, without departing from the scope of the invention.

In the example illustrated in Figures 3 and 4 , the cells 13 in which are inserted the feet 14 of the blades 16 are oriented axially, but the invention also applies to configurations in which the direction of the cells forms an angle with the axial direction of the turbomachine.

Claims (8)

1. A device for rotationally blocking a ring (20) for retaining blades (16) on a rotor disk (10) of a turbomachine in a substantially axial direction of said turbomachine,
   said rotor disk (10) being provided with hooks (6, 62, 64, 66) spread around its circumference and defining a groove (22) for accommodating said retaining ring (20), including in succession a first blocking hook (62), a second blocking hook (64) and a third blocking hook (66), said second blocking hook (64) being situated between said first and third blocking hooks (62, 66), and said retaining ring (20) being provided with a split (24) and with two cleats (30) arranged on a ring face on either side of said split (24),
   wherein the position of said cleats (30) on said retaining ring (20) is such that, when said retaining ring (20) is in place in said groove (22), said two cleats (30) are in respective abutment against said first blocking hook (62) and against said third blocking hook (66), and said split (24) is covered by said second blocking hook (64).
2. The rotation-blocking device as claimed in claim 1, wherein:

   said first (62) and third (66) blocking hooks are each provided with a check face (144) on their side which is opposite to the side facing said second blocking hook (64), and

   said cleats (30) of said retaining ring (20) are each provided with a contact face (32) oriented toward said split (24), and

   said check faces (144) cooperate with said contact faces (32) in order to bring said cleats (30) into abutment against said first (62) and third blocking hooks (66).
3. The blocking device as claimed in either of claims 1 and 2, in which said groove (22) has two walls, one internal wall which is closer to the rotor disk (10) and one external wall which is further from the rotor disk (10), wherein each check face (144) is situated on the corresponding blocking hook (62, 66) and extends in the axial direction, starting from the free surface of said blocking hook (62, 66) and continuing as far as the internal wall of said groove (22).
4. The blocking device as claimed in claim 2 or 3, wherein said check faces (144) are oriented in a radial plane of said rotor disk (10).
5. The blocking device as claimed in claim 2 or 3, wherein said check faces (144) are oriented in an oblique plane with respect to a radial plane of said rotor disk (10).
6. A turbomachine rotor, which comprises a blocking device as claimed in any one of claims 1 to 5.
7. Turbomachine characterized in that it comprises a blocking device as claimed in any one of claims 1 to 5.
8. Turbomachine according to claim 7, characterized in that it is an aircraft engine.

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