FR3085413A1 - COUPLING FOR CURVIC TYPE TURBOMACHINE WITH LOCK - Google Patents

Abstract

The invention relates to a coupling for a turbomachine, comprising a first and a second disc (17, 18) joined along an axis (AX), and extending in majority respectively from a first and from a second side ( C1, C2) of a median plane (PM) normal to the axis (AX), the first and second discs (17, 18) being provided with first and second teeth (19, 21 respectively) engaging each other across the midplane (PM) to form a curvy bond. According to the invention: - several first teeth (19) each have a first protuberance (19b) projecting towards the axis (AX) extending from the second side (C2); - Several second teeth (21) each have a second protuberance (21b) projecting towards the axis of rotation (AX) extending from the first side (C1); - The first protrusions (19b) are spaced from the second protrusions (21b) along the axis (AX); - At least one blocking member is attached to bear against first and second protrusions (21b) for axially blocking the first element (17) relative to the second element (18).

Description

COUPLING FOR CURVIC TYPE TURBOMACHINE WITH LOCK

DESCRIPTION

TECHNICAL AREA

The invention relates to the coupling of two rotary elements such as discs carrying blades in a turbomachine type engine, by means of a “curvic” type connection.

PRIOR STATE OF THE ART

In such an engine, outside air is admitted into an inlet sleeve to pass through a blower comprising a series of rotary blades before splitting into a central primary flow and a secondary flow surrounding the primary flow.

The primary flow then passes through a high pressure compressor before arriving in a combustion chamber, after which it expands by successively passing through a high pressure turbine and a low pressure turbine before being evacuated after recovery of energy for training blower and generating thrust. The secondary flow is propelled directly backwards by the blower to also generate a thrust.

To allow energy recovery, the high pressure turbine is linked in rotation with the high pressure compressor to drive it in rotation, and the blower is linked in rotation with the low pressure turbine by which it is driven in rotation, the most of the thrust being generated by the blower.

The compressor or turbine parts of such an engine most often comprise several stages formed by rotary elements secured in rotation to each other to rotate about an axis of rotation AX of the engine.

In this context, FIG. 1 shows a high pressure turbine 1 comprising a part 2 including a first stage 3 and a second stage 4 downstream of the first stage with respect to the direction of flow of the flow. The first stage 3 comprises a first disc 6 carrying a first series of vanes 7, the second stage comprising a second disc 8 carrying a second series of vanes 9. A distributor 11 formed from a series of fixed vanes 12 is interposed between the first series of moving blades and the second series of moving blades. Each disc has a central opening and has vanes at its outer periphery.

As can be seen in this FIG. 1, the first disc 6 is attached to the second disc 8 along the axis AX, and it is coupled in rotation to this first disc by a link of the “curvic coupling” type, also called dog clutch or link trapezoidal toothing.

The connection of the two discs which appears more clearly in FIGS. 2 and 3 comprises first trapezoid teeth 13 carried by the first disc 6 which are oriented towards the second disc 8, and second trapezoid teeth 14 carried by the second disc while being oriented to the first disc 6.

In the case of Figures 2 and 3, the first and the second disc are uncoupled by being spaced from each other, which allows their teeth to appear. When the arrangement is in service as in the case of FIG. 1, the discs are coupled by the fact that they are applied one against the other, the first teeth being engaged with the second teeth according to an assembly of creneaumortaise type. allowing to transfer a couple from one disc to another.

The choice of a coupling by curvic link notably allows the discs to center independently of each other around the axis of rotation during operation, while effectively transferring a moment of force from a disc to the 'other. This coupling also makes it possible to facilitate the assembly and disassembly of the rotor of which the disks which compose it form part while having a limited bulk.

However, if one of the discs loses one of the blades which it carries, the axial forces to which it is subjected become unbalanced, as illustrated diagrammatically in FIG. 4. In practice, the disc having lost one or more blades then tends to tilt relative to its nominal orientation, which can lead to uncoupling of the two discs, illustrated in FIG. 5. In the event of uncoupling, the disc can enter an overspeed state leading to its explosion and / or its motor output.

The object of the invention is to provide a solution making it possible to avoid uncoupling of an interdisc link of the curvic type, in particular in the event of the loss of a blade.

STATEMENT OF THE INVENTION

To this end, the subject of the invention is a coupling for a turbomachine between a first element and a second element which extend around an axis while being engaged one inside the other along the axis, each element comprising teeth which extend axially to be engaged in a respective concavity of the other element, characterized in that it comprises less a blocking member which cooperates with blocking means carried by the teeth of the first and second elements for axially block the first element relative to the second element.

With this solution, the uncoupling of the first and second elements is prevented in the axial direction, which is particularly effective in avoiding overspeed phenomena which can lead to damage to the rotor of the turbomachine in the event of separation between these two elements in operation . In addition, the size of the locking means is limited by the fact that they are as close as possible to the coupling teeth.

The invention also relates to a coupling thus defined, in which:

- Several teeth of the first element each have a first retention face;

- Several teeth of the second element each have a second retention face;

- The at least one blocking member enclosing the first and the second retention faces to axially block the first element relative to the second element.

The invention also relates to a coupling thus defined, in which the first retention faces are turned towards the first element and in which the second retention faces are turned towards the second element.

The invention also relates to a coupling thus defined, in which each retention face is formed by a protuberance extending a tooth and having a rectilinear shape of radial orientation directed towards the axis of rotation.

The invention also relates to a coupling thus defined, comprising a locking member which is a split ring with a U-section.

The invention also relates to a coupling thus defined, in which certain teeth have no protuberance.

The invention also relates to a turbine comprising a coupling thus defined.

The invention also relates to a turbomachine comprising a turbine thus defined.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 already described is a sectional view of a portion of known high pressure turbine;

FIG. 2 already described is a perspective view of a known curvy type connection portion;

FIG. 3, already described, is a diagrammatic flat view of a connection portion of known curvic type;

FIG. 4 already described is a side view showing an imbalance in the distribution of forces in a known curvy connection in the event of the loss of a blade;

Figure 5 already described is a perspective view showing a uncoupling of a known curvy link;

Figure 6 is a schematic flat view of a curvy connecting portion according to the invention;

Figure 7 is a schematic sectional view of a curvy connection according to the invention;

Figure 8 is a perspective view of a curvy connecting portion according to the invention;

Figure 9 is a perspective view of a half curvy link according to the invention.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

The basic idea of the invention is to take advantage of the alternating overlapping of the teeth of the curvy connection to maintain an annular blocking member by protuberances protruding from the teeth radially towards the axis.

In FIG. 6, a schematic flat view of a portion of a connection 16 of the curvic type according to the invention ensures the coupling of a first disc 17 with a second disc 18 which rotate around an axis AX in being joined to each other along this axis.

The first disc 17 carries on one of its faces a first toothing extending along a crown centered on the axis AX, this first toothing being formed by first regularly spaced trapezoidal teeth 19 which are oriented towards the second disc 18.

The second disc 18 carries on one of its faces a toothing extending along a crown centered on the axis AX, this second toothing being formed by second trapezoidal teeth 21 regularly spaced apart and oriented towards the first disc 17.

Each tooth 19 of the first disc 17 has a trapezoidal main profile 19a oriented axially and directed towards the second disc, and a protrusion 19b which protrudes from this main profile 19a and extends towards the axis AX. Similarly, each tooth 21 of the second disc 18 has a main trapezoidal profile 21a oriented axially and directed towards the first disc, and a protuberance 21b which protrudes from this main profile and extends towards the axis AX.

The first disc 17 is coupled in rotation with the second disc 18 by interlocking the main profiles 19a, 21a with each other which constitute the teeth proper, and by means of which a torque is transferred from a disc towards each other when the assembly is in service. Each tooth is thus engaged in a concavity delimited by the interval separating two consecutive teeth from the other disc.

Each first protrusion 19b defines a trapezoidal profile 19a of a first tooth 19 belonging to the first disc and which is oriented towards the axis AX, a cylindrical internal face 22 being common to the first teeth 19. Similarly, each second protrusion 21b defines a trapezoidal profile 21a of a second tooth 21 belonging to the second disc and which is oriented towards the axis AX, a cylindrical internal face 23 being common to the second teeth 21.

As shown in FIGS. 6 and 7, each first protuberance 19b forms a first retention face 19c facing the first disc 17, and similarly each second protuberance 21b forms a second retention face 21c facing the second disc 18.

The first retention faces 19c and the second retention faces 21c are arranged alternately on either side of a median plane PM normal to the axis AX. This median plane PM corresponds to the mean plane of the coupling: the first disc 17 is situated essentially on a first side C1 of the plane PM, and the second disc is located essentially on a second side C2 of the plane PM, opposite to the first side C1. The faces 19c all extend in a region located on the first side C1 and the faces 21c all extend in a region located on the second side C2.

The first trapezoidal profiles cross the median plane PM, so that the first retention faces 19c extend from the first side C1. And similarly, the second trapezoidal profiles 21a cross the median plane PM, so that the second faces of retention 21c extend from the second side C2.

The first protrusions 19b are spaced from the second protrusions 21b along the axis AX, to jointly delimit a radially internal circumferential rim projecting from the internal cylindrical faces 22 and 23, to receive a locking member 24 which is here a locking ring which grips them to lock the link.

As can be seen in particular in FIGS. 8 and 9, each first protuberance 19b has a rectilinear shape and extends radially towards the axis AX, and similarly each second protuberance 21b has a rectilinear shape and extends radially towards the axis AX.

When the assembly is mounted, as shown in FIGS. 6 to 9, the ring 24 encloses the annular rim formed by the first and the second protuberances arranged along the median plane PM, bearing on the retention faces 19c and 21c which form the axial faces of this circular rim.

As visible in Figure 7, the ring 24 has in section a shape corresponding to the letter U: it constitutes an open rail on the side of its external periphery to overlap the flange formed by the first and second protrusions when it is in place, in order to enclose them axially. The width of this rail along the axis AX corresponds to the thickness of the internal rim formed by the protrusions along the axis AX.

The ring 24 thus axially surrounds the first retention faces 19c and the second retention faces 21c to block them relative to each other along the axis AX, so that they form a locking s opposing any separation of the first disc relative to the second disc.

The ring 24 is also blocked radially by the radially internal faces of the first and second protuberances against which it bears and which oppose the radial expansion of this ring 24 by centrifugal effect, and it is blocked longitudinally by the faces retention 19c, 21c which it overlaps.

The assembly constituted by the ring 24 and the protrusions 19b, 21b thus forms a stable locking of the curvic connection which prevents the axial disengagement of the latter, while being removable for example for a maintenance or assembly operation of the engine. .

In the example of the figures, each tooth is provided with a protuberance, but only a part of the teeth can be provided with such protrusions, for example one tooth in two or one tooth in three. In practice, the connection comprises a minimum of three first protrusions extending three first teeth and three second protrusions extending three second teeth.

Once the first disc 17 has been fitted against the second disc 18, to engage the first toothing with the second toothing, an operator engages one end of the split ring 24 on the protrusions 19b, 21b, and pushes this ring radially on them until it overlaps their entire circumference.

In the example of FIG. 9, the locking member 24 has the general shape of a split ring of U-section, comprising a first end 26 and a second end 27 slightly spaced from one another.

The ring 24 is advantageously made of a material having an appropriate flexibility to allow an operator to tighten it and deploy it radially so as to engage it on the protuberances.

In the example of the figures, the blocking member is a single ring which overlaps all the protrusions. The connection according to the invention can also be blocked by several blocking members each enclosing several first and second retention faces.

These locking members are then located circumferentially one after the other, being held by the clamping which they exert on the protuberances and by centrifugal effect when the engine is running. These locking members can be in the form of two or more complementary ring sections whose ends are contiguous or spaced from each other when they are in place to block the coupling.

The fact of using one or more locking members generally forming a ring axially enclosing the protrusions ensures that the discs 5 retain the possibility of being centered independently of one another on the axis AX, while ensuring that they cannot uncouple.

Claims (8)

1. Coupling for a turbomachine between a first element (17) and a second element (18) which extend around an axis (AX) while being engaged one inside the other along the axis (AX) , each element (17, 18) comprising teeth (19, 21) which extend axially to be engaged in a respective concavity of the other element, characterized in that it comprises at least one locking member (24) which cooperates with locking means carried by the teeth (19, 21) of the first and second elements (17, 18) for axially locking the first element (17) relative to the second element (18). 2. Coupling according to claim 1, in which: - Several teeth (19) of the first element (17) each have a first retention face (19c); - Several teeth (21) of the second element (18) each have a second retention face (21c); - The at least one blocking member (24) enclosing the first and the second retention faces (19c, 21c) for axially blocking the first element (17) relative to the second element (18). 3. Coupling according to claim 2, in which the first retention faces (19c) are turned towards the first element (17) and in which the second retention faces (21c) are turned towards the second element (18). 4. Coupling according to claim 2, in which each retention face (19c, 21c) is formed by a protuberance (19b, 21b) extending a tooth and having a rectilinear shape of radial orientation directed towards the axis of rotation (AX ). 5. Coupling according to claim 2, comprising a locking member (24) which is a split ring with a U-section. 6. Coupling according to one of claims 2 to 5, in which certain teeth (19, 21) are devoid of protuberance. 5 7. Turbine comprising a coupling according to one of the preceding claims. 8. A turbomachine comprising a turbine according to claim 7.