Rotating part for an aircraft turbine engine

Abstract

The invention relates to a rotating part for an aircraft turbine engine, comprising a plurality of teeth (26) defining between them at least one groove (28), the radius of curvature of the bottom (30) of the at least one groove (28) being greater than or equal to the distance (D) between said bottom (30) and the axis (X) of the rotating part.

Description

ROTATING PART FOR AIRCRAFT TURBOMACHINE Technical field

[0001] This disclosure relates to a rotating part for an aircraft turbomachine, and more particularly to a grooved rotating part for the transmission of mechanical power within an aircraft turbomachine. Prior art

[0002] In aircraft turbomachinery, mechanical power transmission can be achieved using a so-called splined connection, in which two rotating parts with complementary teeth and splines are engaged with each other. In this way, the torque associated with one part is transmitted to the other part.

[0003] The geometry of the splines can be partly defined with reference to ISO or ANSI standards. However, these standards allow designers a certain degree of design freedom, particularly to achieve mechanical strength objectives. Thus, there is a need for a new type of rotating part for aircraft turbomachinery. Statement of the invention

[0004] To this end, the present disclosure relates to a rotating part for an aircraft turbomachine, comprising a plurality of teeth defining between them at least one groove, the radius of curvature of the bottom of the at least one groove being greater than or equal to the distance between said bottom and the axis of the rotating part.

[0005] The axis of the rotating part is called the axis of rotation of the rotating part. The axial direction corresponds to the direction of the axis of the rotating part and a radial direction is a direction perpendicular to this axis and intersecting this axis. Similarly, an axial plane is a plane containing the axis of the rotating part and a radial plane is a plane perpendicular to this axis. A circumference is understood as a circle belonging to a radial plane and whose center belongs to the axis of the rotating part. A tangential or circumferential is a direction tangent to a circumference; it is perpendicular to the axis of the rotating part but does not pass through the axis.

[0006] Unless otherwise specified, the adjectives interior and exterior are used with reference to a radial direction so that the interior part of an element is, in a radial direction, closer to the diffuser axis than the exterior part of the same element.

[0007] In this disclosure, and unless otherwise indicated, "a" or "the" groove means "at least one" or "the at least one" or "each" groove. Conversely, the generic use of the plural may include the singular.

[0008] The bottom of a groove refers to the part of the groove that is furthest back from the teeth.

[0009] The curvature of the bottom can be considered transverse to the teeth, generally in a radial plane. The characteristics described in this presentation are valid in at least one radial plane, preferably in any radial plane.

[0010] The radius of curvature is considered as an absolute value.

[0011] Due to the fact that the radius of curvature of the bottom of the groove is greater than or equal to the distance between said bottom and the axis of the rotating part, the bottom of the groove is flattened compared to previously known devices, which has several advantages: on the one hand, this bottom is easier to manufacture and its dimensions are easier to control than more curved bottoms, having a smaller radius of curvature. On the other hand, such a bottom makes it possible to better distribute the stresses within the groove, which results in better mechanical strength of the rotating part.

[0012] In the case where the radius of curvature of the bottom is equal to the distance between the bottom and the axis of the rotating part, the center of curvature of the bottom can, depending on the concavity, belong to the axis of the rotating part. In this case, the geometric specification of the groove is further simplified, since the radius of curvature of the bottom and the distance between the axis and the bottom are one and the same parameter.

[0013] In some embodiments, each tooth has a head bordered by two flanks. The groove may be defined between a flank of one tooth and an opposing flank of an adjacent tooth. The head of the tooth projects relative to the bottom of the groove.

[0014] In some embodiments, the tooth head extends, from one flank to the other, along an arc of a circle centered on the axis of the rotating part. The geometry of the tooth head is therefore simplified.

[0015] In some embodiments, each flank extends along an involute of a circle to the head. The involute of a circle is a curve known in itself in the context of splined connections. However, the fact that this involute of a circle extends to the head indicates in particular that the flank and the head meet without a chamfer or other form of transition. This makes it possible to increase the contact surface between the flank concerned and the complementary part, thus better distributing the forces and further increasing the mechanical strength of the part. In addition, thanks to these arrangements, the head of the tooth can be provided set back relative to the head of the tooth of the previous rotating parts, which improves compatibility with the complementary part and lightens the rotating part.

[0016] In some embodiments, a connecting radius connects the bottom of the groove to at least one of the flanks of said groove. A connecting radius designates a curved portion, in particular an arc of a circle, making it possible to ensure a continuous and derivable transition between, here, the flank and the bottom. The connecting radius generally has a radius of curvature different from those of the bottom and the flank. This radius of curvature can be constant.

[0017] In some embodiments, the teeth project toward the axis of the rotating part. The rotating part is therefore sometimes referred to as an outer part, since it is configured to receive and engage an inner part. The teeth of the outer part project toward the inner part and may be received in splines or the like, while the splines of the outer part receive teeth or the like of the inner part.

[0018] In some embodiments, the rotating part comprises a succession of teeth and splines arranged along a circumference.

[0019] In some embodiments, the rotating part is a fan disk, a compressor shaft, or a turbine shaft. A fan disk may carry fan blades and be driven by a fan shaft, a turbine shaft, or a reduction gear, via a splined connection. A compressor shaft is configured to rotate a compressor disk, for example via a splined connection, and may be driven by a turbine shaft or a reduction gear, for example via a splined connection. A turbine shaft may be driven by a turbine disc, for example via a splined connection, and may drive a fan shaft, a compressor shaft or a reduction gear, for example via a splined connection. However, other turbomachine parts are envisaged.

[0020] In some embodiments, the teeth extend, in the direction of the axis of the rotating part, in a straight, helical or curved profile.

[0021] This disclosure also relates to an aircraft turbomachine, comprising a rotating part as previously described. The rotating part may have all or part of the characteristics previously mentioned. Brief description of the drawings

[0022] Other characteristics and advantages of the subject of the present disclosure will emerge from the following description of embodiments, given as non-limiting examples, with reference to the appended figures.

[0023] Figure 1 represents a schematic axial section view of a turbomachine.

[0024] Figure 2 represents, in radial section along plane II-II of figure 1, a detail of a rotating part according to one embodiment. Detailed description

[0025] Figure 1 illustrates a turbomachine, more precisely a twin-spool turbojet engine, as an example of an aircraft turbomachine comprising a rotating part. In this case, the turbomachine 10 is an aircraft turbomachine comprising a shaft 12, in this case a low-pressure spool shaft, and a fan disk 14 provided to carry fan blades and rotating about an axis X defining an axial direction. The axis X here coincides with the axis of the turbomachine. In this example, the turbomachine 10 also comprises another shaft 16, in this case a high-pressure spool shaft, mounted coaxially outside the shaft 12.

[0026] The shaft 12, driven in rotation under the effect of the passage of combustion gases by a turbine, is configured to drive the fan disc 14 in rotation. The fan disc 14 is an example of a rotating part for an aircraft turbomachine. To ensure this rotational drive, the shaft 12 and the fan disc 14 are engaged with each other by means of a splined connection.

[0027] An embodiment of such a grooved connection is illustrated in Figure 2, in radial section.

[0028] The shaft 12 is housed inside the fan disc 14. Thus, the shaft 12 forms an internal part, while the fan disc 14 forms an external part. The shaft 12 and the fan disc 14 are here coaxial around the X axis.

[0029] The shaft 12 may comprise teeth 22 defining between them splines 24. The teeth 22 project outwards. However, the shaft 12 may have any other shape allowing the transmission of torque to the fan disc 14, the geometry of which will be described below. Furthermore, the shaft 12 may be a certified part in itself, which requires it to be kept as such to avoid a new certification process. The dimensioning of the fan disc 14 must then take into account the given shape of the shaft 12.

[0030] The fan disc 14 comprises a plurality of teeth 26 defining between them at least one groove 28. In this case, each pair of teeth 26 defines between these teeth 26 a groove 28, so that the fan disc 14 comprises, in a circumferential direction, a succession of teeth 26 and grooves 28, alternating. Subsequently, a tooth 26 and a groove 28 are described generically, but the characteristics mentioned may apply to all the teeth 26 and / or grooves 28, or some of them. In particular, the teeth 26 and / or the grooves 28 may all be identical.

[0031] The tooth 26 projects towards the X axis of the fan disc 14, for example substantially in a radial direction. In the axial direction, the tooth 26 may extend in a rectilinear or helical manner. Furthermore, the cross-section of the tooth 26 may be constant or not, for example follow a domed profile in which the section is relatively narrow at the axial ends and relatively wide in an intermediate portion, or vice versa.

[0032] The groove 28 comprises a bottom 30, which designates the part of the groove 28 that is furthest set back from the teeth 26. In this embodiment, the radius of curvature of the bottom 30 of the groove 28 is greater than or equal to the distance D between said bottom 30 and the axis X of the fan disk. The radius of curvature of the bottom 30 may be constant circumferentially and / or axially. If the radius of curvature of the bottom 30 is not constant, the smallest radius of curvature of the bottom 30 is considered, which is nevertheless greater than or equal to the distance D.

[0033] In particular, in the example shown, the radius of curvature of the bottom 30 is equal to the distance D. The bottom 30 therefore extends along an arc of a circle centered on the X axis.

[0034] In any case, the bottom 30 has a relatively high radius of curvature, which is clearly apparent by visually comparing the curvature of the bottom 30 and the curvature of the bottom of the groove 24 of the shaft 12.

[0035] In this embodiment, each tooth 26 has a head 32 bordered by two flanks 34. The groove 28 is here defined between two opposite flanks 34 of two consecutive teeth 26.

[0036] As mentioned previously, the head 32 may extend, from one flank 34 to the other, along an arc of a circle centered on the axis X of the fan disc 14. The head 32 may, here, be concave. The head 32 therefore adopts a continuous and regular shape from one of the flanks 34 to the other of the flanks 34. In particular, the head 32 may be devoid of a chamfer or connecting radius with the flanks 34. The head 32 and the flanks 34 may meet at a sharp edge 36. This makes it possible to increase the contact surface of the tooth 26 with the shaft 12 for the transmission of the torque.

[0037] The distance between the head 32 and the axis X of the fan disc 14 can be determined as a function of the complementary part, namely here as a function of the groove 24 of the shaft 12, in order to prevent contact of the tooth 26 with the bottom of the groove 24. Indeed, the torque is transmitted to the fan disc 14 at its flanks 34, and it is preferable to provide a space between the head 32 of the fan disc 14 and the bottom of the grooves 24 of the shaft 12 on the one hand, and the bottom 30 of the fan disc 14 and the head of the teeth 22 of the shaft 12 on the other hand.

[0038] In order to better transmit the torque, the flank 34, for its part, can extend according to an involute of a circle. An involute of a circle is a curve known per se by those skilled in the art, so the normals are tangents to the same circle. More generally, the flanks 34 are convex. Independently, the flanks of the teeth 22 of the shaft 12 can also extend along an involute of a circle.

[0039] The involute surface of the flank 34 extends to the head 32: in other words, the involute is adjacent to the head 32, possibly to the arcuate shape of the head 32 described above.

[0040] On the side of the base 30, a connecting radius 38 can connect the base 30 of the groove 28 to at least one of the flanks 34 of the tooth 26 defining this groove 28. The connecting radius 38 has a radius of curvature different from that of the flank 34 and the base 30, generally less than that of the flank 34 and / or the base 30 at the junction points of the connecting radius 38 with the flank 34 and the base 30, respectively.

[0041] Connection radii, identical or not, may be provided on either side of the bottom 30. In the present embodiment, the groove 28 is symmetrical.

[0042] The fact that the bottom 30 has a relatively large radius of curvature means that the connecting radius 38 is located further towards the bottom of the fan disc 14 and therefore encroaches less on the flank 34, which provides the flank 34 with a larger contact surface.

[0043] According to one example, the radius of curvature of the bottom and the distance D may be between 170 and 190 millimeters. The radial distance between the bottom 30 and the head 32 may be between 3 and 10 millimeters. Axially, the groove 28 may extend over 40 to 60 millimeters. The radius of curvature of the connecting radius 38 may be between 0.5 and 1.5 millimeters.

[0044] Tests conducted by the inventors have made it possible to demonstrate, using numerical calculations, that the new geometry of the bottom 30 made it possible to reduce the stresses in the fan disc 14 and therefore to improve the mechanical strength of this disc. Typically, under a given load, the maximum stress in the groove 28 went from 617 MPa with a conventional fan disc to 588 MPa with a fan disc 14 according to the present embodiment, i.e. a reduction of almost 5%.

[0045] The splined connection of the proposed fan disc 14 is designed from bottoms 30, connecting radii 38, sides 34 and heads 32. Each of these surfaces is relatively large, as opposed to small transition surfaces, and inherently simple in shape, which facilitates dimensional control of the fan disc 14.

[0046] Although the present description refers to specific exemplary embodiments, modifications may be made to these examples without departing from the general scope of the invention. For example, although a fan disk 14 has been described as an example of a rotating part, the described characteristics may apply to other rotating parts for an aircraft turbomachine, for example a compressor shaft or a turbine shaft, of high or low pressure spool. Furthermore, although the characteristics have been detailed in the context of an external part whose teeth project inwardly, they could also apply to an internal part whose teeth project outwardly. Furthermore, although a double-flow, double-spool turbojet engine has been described, the rotating part may be incorporated into a turbomachine having any desired type of architecture.More generally, individual features of the various embodiments illustrated or mentioned may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

CLAIMS

1. Rotating part for an aircraft turbomachine, comprising a plurality of teeth (26) defining between them at least one groove (28), the radius of curvature of the bottom (30) of the at least one groove (28) being greater than or equal to the distance (D) between said bottom (30) and the axis (X) of the rotating part.

2. Rotating part according to claim 1, in which each tooth (26) has a head (32) bordered by two flanks (34).

3. Rotating part according to claim 2, in which the head (32) extends, from one flank (34) to the other, along an arc of a circle centered on the axis (X) of the rotating part.

4. A rotating part according to claim 2 or 3, wherein each flank (34) extends along an involute of a circle to the head (32).

5. A rotating part according to any one of claims 1 to 4, wherein the teeth (26) project towards the axis (X) of the rotating part.

6. A rotating part according to any one of claims 1 to 5, wherein the rotating part is a fan disc (14), a compressor shaft or a turbine shaft.

7. A rotating part according to any one of claims 1 to 6, wherein the teeth (26) extend, in the direction of the axis (X) of the rotating part, in a rectilinear, helical or curved manner.

8. Turbomachine (10) for aircraft, comprising a rotating part according to any one of claims 1 to 7.

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