COUPLING SHAFT FOR AN AIRCRAFT TURBOMACHINE

Abstract

Coupling shaft (8b) for an aircraft turbomachine (1), this shaft (8b) extending along and around a longitudinal axis (A) and comprising an annular wall (8ba) which comprises a first longitudinal end connected by a first annular web (34) to a first annular flange (38), and a second longitudinal end connected by a second annular web (26) to a second annular flange (28), each of the first and second webs (26, 34) comprising an inner periphery connected to the annular wall (8ba) and an outer periphery connected to the corresponding flange (28, 38) which extends radially outwards from this outer periphery, characterized in that said first web (34) has a generally frustoconical shape which flares from its inner periphery to its outer periphery on the side of said second web (26). Figure for abstract: Figure 6

Description

Title of the invention: COUPLING SHAFT FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The present invention relates to a coupling shaft for an aircraft turbomachine, and to an aircraft turbomachine comprising such a shaft. The coupling is of the / Zev coupling type. Technical background

[0002] The state of the art includes in particular documents FR-A1-2 979 121, FR-Al-3 075 878 and FR-A1-3 075 880.

[0003] A turbomachine, such as a dual-flow turbojet, conventionally comprises an air inlet comprising a fan whose outlet air flow is divided into an air flow which enters the engine and forms a hot flow or primary flow, and into an air flow which flows around the engine and which forms a cold flow or secondary flow.

[0004] The engine typically comprises from upstream to downstream, in the direction of gas flow, at least one compressor, a combustion chamber, at least one turbine, and an ejection nozzle in which the combustion gases leaving the turbine and forming the primary flow are mixed with the secondary flow. A turbomachine can also be of the "double-body" type, which means that it comprises two rotors arranged coaxially. A first body is called a low-pressure body and a second body is called a high-pressure body. In a known manner, the engine comprises in this case, from upstream to downstream, a low-pressure compressor, a high-pressure compressor, the combustion chamber, a high-pressure turbine and a low-pressure turbine.

[0005] In the case of a turbomachine with a reduction gear, the turbine shaft drives the fan shaft via the reduction gear which is lubricated and housed in a lubrication enclosure. Depending on the type of reduction gear used, planetary or epicyclic, the fan shaft will rotate in the same direction or in the opposite direction to the turbine shaft, and the fan shaft will rotate at a lower speed than that of the turbine shaft.

[0006] The turbine shaft, which is the low-pressure turbine shaft in the case of a twin-spool turbomachine, is generally coupled to a low-pressure compressor shaft which is itself coupled to an input shaft of the reducer. This input shaft passes through the reducer and engages the latter's sun gear.

[0007] To ensure proper operation of this low pressure shaft line and in particular of the reducer, it is necessary to transmit the torque but, at the same time, obtain a certain flexibility in the input shaft of the reducer so as not to cause transit significant efforts in the reducer due to displacements at the imposed interfaces.

[0008] One solution is to connect the shafts of the shaft line by coupling devices which provide a certain flexibility to the shaft line in operation.

[0009] Among the known coupling devices for a turbomachine, we can cite the technologies designated by their English names “flex coupling” and “curvic coupling”.

[0010] The aforementioned documents describe coupling devices of the "flex coupling" type. In this type of device, two shafts are connected together by flanges tightened against each other by means of screws which ensure the transmission of torque between the shafts.

[0011] The flanges are located at the outer periphery of webs that extend radially outward from the tubular bodies of the shafts. It is the presence of these webs that makes it possible to provide flexibility to the coupling. More particularly, the geometry and dimensions of the webs make it possible to adjust the flexibility of the coupling.

[0012] In operation, due to the centrifugal forces which are applied to the shaft line, the presence of this type of coupling induces an axial contraction effect of the shaft line.

[0013] Furthermore, a mechanical reducer is sensitive to misalignments, in particular axial misalignments, because this generates an additional axial force that the teeth of the reducer must take up.

[0014] The two phenomena which contribute to these misalignments are the axial displacements imposed by the engine and the aforementioned axial deformation of the shaft line under centrifugal effect.

[0015] The greater the stiffness of the shaft line, the greater the axial force because this axial force is proportional to this stiffness.

[0016] In order to limit this axial force, one solution would therefore be to minimize the axial stiffness of the shaft line or to have an axial deformation of this shaft line which is as close as possible to the displacements imposed by the engine, so that the difference between the two tends towards zero. In other words, the shaft line would have to be able to absorb the displacements imposed by the engine.

[0017] However, with current auflex coupling technology, the axial contraction of the shaft line is added to the displacements imposed by the motor and the reduction of the axial stiffness of the shaft increases this axial contraction effect.

[0018] The present invention provides a simple, effective and economical solution to the need expressed above. Summary of the invention

[0019] The invention relates to a coupling shaft for an aircraft turbomachine, this shaft extending along and around a longitudinal axis and comprising an annular wall which comprises a first longitudinal end connected by a first annular web to a first annular flange, and a second longitudinal end connected by a second annular web to a second annular flange, each of the first and second webs comprising an inner periphery connected to the annular wall and an outer periphery connected to the corresponding flange which extends radially outwards from this outer periphery, characterized in that said first web has a generally frustoconical shape which flares from its inner periphery to its outer periphery on the side of said second web.

[0020] In the current technique, the sails each have a perfectly radial orientation or have a truncated cone shape, flaring out on the side opposite the shaft. This particular shape causes the aforementioned phenomenon of axial contraction of the shaft under centrifugal effect. To counter this phenomenon and even reverse it, the truncated cone shape of at least one of the sails of the shaft is reversed, this sail now flaring out on the side of the other sail of the shaft, that is to say on the side of the shaft.

[0021] In operation, the centrifugal forces will now cause an axial extension of this web and therefore of the shaft. This axial extension opposes the axial displacement imposed by the engine in operation. The reverse-conical web can be configured, and in particular dimensioned, so that the axial extension exactly compensates for the axial displacement imposed by the engine. Thus, the shaft line of the turbomachine is not subjected to axial stress and is not likely to generate misalignments in the teeth of the reducer.

[0022] In the case where the axial extension generated by one of the reverse-conical sails of the shaft would not be sufficient to compensate for the axial displacement imposed by the motors, the two sails of the shaft could have reverse-conical so that the sum of their axial extensions compensates for this axial displacement.

[0023] The coupling shaft according to the invention may comprise one or more of the following characteristics, taken in isolation from one another, or in combination with one another:

[0024] - said second veil has a general truncated cone shape which flares out from its periphery internal to its external periphery on the side of said first veil;

[0025] said second web has a generally truncated cone shape which flares from its internal periphery to its external periphery on the side opposite said first web;

[0026] - the second veil forms an angle [3 with a plane perpendicular to the longitudinal axis and passing through the second flange, this angle [3 being between 1 and 40°, and preferably between 1 and 30°, and being measured in another plane passing through the longitudinal axis;

[0027] - the first veil forms an angle a with a plane perpendicular to the longitudinal axis and passing through the first flange, this angle a being between 1 and 40°, and preferably between 1 and 30°, and being measured in another plane passing through the longitudinal axis;

[0028] - the angles a and [3 are different;

[0029] - the angles a and [3 are identical;

[0030] — angle a is positive or negative;

[0031] — angle b is positive or negative;

[0032] - each of said first and second sails has a minimum thickness less than a minimum thickness of said wall;

[0033] - the annular wall comprises an inner annular surface which is connected by a first radius of curvature at a first surface of each of the webs, and an outer annular surface which is connected by a second radius of curvature to a second surface of each of the webs, the first and second radii of curvature at the first web being different and / or the first and second radii of curvature at the second web being different.

[0034] The present invention also relates to an aircraft turbomachine, comprising three shafts extending along and around a longitudinal axis and integral in rotation around this axis, these three shafts comprising:

[0035] - an upstream shaft comprising an annular wall of which one longitudinal end downstream is connected by an annular web to an annular flange, this web comprising an internal periphery connected to the annular wall and an external periphery connected to the flange which extends radially outwards from this external periphery,

[0036] - a downstream shaft comprising an annular wall, one longitudinal end of which upstream is connected by an annular web to an annular flange, this web comprising an internal periphery connected to the annular wall and an external periphery connected to the flange which extends radially outwards from this external periphery, and

[0037] - a coupling shaft as described above interposed between the upstream shafts and downstream, the coupling shaft flanges being respectively fixed to the flanges of the upstream and downstream shafts.

[0038] The turbomachine according to the invention may comprise one or more of the following characteristics, taken in isolation from one another, or in combination with one another:

[0039] - the first flange is fixed to the flange of the upstream shaft, the web of this upstream shaft having a generally truncated cone-shaped shape which flares from its internal periphery to its external periphery on the side opposite the coupling shaft, or

[0040] - the first flange is fixed to the flange of the downstream shaft, the web of this downstream shaft having a general truncated cone shape which flares from its internal periphery to its external periphery on the side opposite the coupling shaft;

[0041] - the internal peripheries of the first web and of the web opposite the upstream shaft or downstream are separated from each other by a distance Dl, and the external peripheries of the first web and the web opposite the upstream or downstream shaft are separated from each other by a distance D2, Dl being less than D2;

[0042] - the second flange is fixed to the flange of the downstream shaft, the web of this upstream shaft having a generally truncated cone-shaped shape which flares from its inner periphery to its outer periphery on the side opposite the coupling shaft, or

[0043] - the second flange is fixed to the flange of the upstream shaft, the web of this upstream shaft having a generally truncated cone shape which flares from its internal periphery to its external periphery on the side opposite the coupling shaft;

[0044] - the second flange is fixed to the flange of the downstream shaft, the web of this downstream shaft having a generally truncated cone-shaped shape which flares from its inner periphery to its outer periphery on the coupling shaft side, or

[0045] - the second flange is fixed to the flange of the upstream shaft, the web of this upstream shaft having a generally truncated cone shape which flares from its internal periphery to its external periphery on the coupling shaft side;

[0046] - the downstream shaft is a turbine shaft or coupled to a turbine shaft, and the downstream shaft is an input shaft of a mechanical reducer or coupled to such an input shaft, the reducer comprising a flexible output coupled to a propeller shaft. Brief description of the figures

[0047] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:

[0048] [Fig-1] [Fig.l] is a schematic axial sectional view of a turbomachine aircraft,

[0049] [Fig.2] [Fig.2] is a larger-scale schematic view of part of the [Fig.l],

[0050] [Fig.3] [Fig.3] is a view similar to that of [Fig.2],

[0051] [Fig.4] [Fig.4] is a schematic half-view in axial section of a device flex coupling type coupling,

[0052] [Fig.5] [Fig.5] is a schematic axial sectional view of a line of shafts and of a coupling shaft according to the prior art,

[0053] [Fig.6] [Fig.6] is a schematic axial sectional view of a line of shafts and of a coupling shaft according to one embodiment of the invention,

[0054] [Fig.7] [Fig.7] is a larger-scale schematic view of part of the [Fig.6], and

[0055] [Fig.8] [Fig.8] is a schematic axial sectional view of a line of shafts and a coupling shaft according to an alternative embodiment of the invention. Detailed description of the invention

[0056] Referring to [Fig.l], we see an aircraft turbomachine 1, which comprises, in a conventional manner, a fan S, a low-pressure compressor 1a, a high-pressure compressor 1b, a combustion chamber 1c, a high-pressure turbine 1d and a low-pressure turbine 1c. The rotors of the high-pressure compressor 1b and of the high-pressure turbine 1d are connected by a high-pressure shaft 5 and form with it a high-pressure (HP) body. The rotors of the low-pressure compressor 1a and of the low-pressure turbine 1c are connected by a low-pressure shaft 4 and form with it a low-pressure (LP) body. The fan S is, for its part, carried by a fan shaft 3 which is connected by a reduction gear 7 to the LP shaft 4.

[0057] The HP and LP shafts 4, 5 extend along an axis A which is the axis of rotation of the turbomachine 1. In the remainder of the description, the notions of longitudinal or radial, and internal or external, relate to this axis A.

[0058] The turbomachine 1 comprises structural casings. The HP body is held by two structural casings: the inter-compressor casing and the inter-turbine casing, and the LP body is held by at least two structural casings: the intermediate casing 2 and the inter-turbine casing and / or the exhaust casing 6.

[0059] The intermediate casing 2 supports bearings of the LP turbine shaft 4 which are housed in a front or upstream enclosure denoted EL. The exhaust casing 6 supports bearings of the LP turbine shaft 4 which are housed in a rear or downstream enclosure denoted E2. The enclosures El, E2 are generally delimited by bearing supports.

[0060] The reducer 7 is here of the epicyclic type. [Fig.2] shows very schematically the size of the reducer 7. The reducer 7 comprises an input shaft 8 extending upstream of the LP shaft 4 and which is guided by a downstream bearing 10.

[0061] The input shaft 8 comprises an axial end, here upstream, engaged in the reducer 7 and meshed with a sun gear of the reducer, which is itself meshed with the satellites of the reducer. The input shaft 8 has its downstream end which is meshed with a shaft 15 of the low pressure compressor which is itself meshed with the shaft 4. The bearing 10 extends here around the shaft 15.

[0062] The output torque of the reducer 7 is transmitted to the fan shaft 3, by a conventional connection, known to those skilled in the art, such as for example a fixing of this fan shaft on the planet carrier forming an output shaft 9 of the reducer, in the case of an epicyclic reducer. In the case of a planetary reducer, the shaft The fan would be driven by the crown of the reducer 7, which is itself meshed with the satellites of the reducer. The reducer 7 is placed inside the enclosure before lubrication El.

[0063] The enclosure El comprises fixed walls and movable walls. The fixed walls of the enclosure El comprise an internal wall of the primary flow vein, an upstream annular support 11 of bearings 13, 14 and a downstream annular support 12 of bearing 10.

[0064] The supports 11 and 12 extend towards the inside of the turbomachine and respectively carry the bearings 13, 14 and the bearing 10. They provide the structure between the casings and the fixed external rings of the bearings 13, 10. The movable walls of the enclosure El comprise the input 8 and output 9 shafts. The bearings 10, 13, 14 are housed in the enclosure EL. Seals, not visible in the diagrams, are provided between the fixed and movable walls and are, for example, labyrinth seals, brush seals, segmented radial seals, etc.

[0065] The bearings 10, 13 and 14 as well as the reducer 7 are lubricated for their proper operation. The oil is supplied by suitable means such as nozzles, oil supply conduits, etc. The bearing support 11 comprises ventilation holes which allow ventilation air to pass through the enclosure. The enclosure E1 is configured so that the air-oil mixture, which forms an oil mist inside the enclosure, is contained in the latter. Between the rotor and stator walls of the enclosure, for example here at the upstream and downstream ends of the enclosure, seals (such as labyrinths) are placed to contain the oil, and an air circuit pressurizes these seals to prevent oil leaks. The El enclosure is then pressurized (air enters continuously, pushing back the oil which could have escaped from the seals by capillarity) and the bearings operate in a medium of mixed oil and air.The supply to the bearings is ensured by a supply tube and the recovery is ensured by a specific recovery tube which extends along the X axis and inside the shaft line, in particular low pressure, as schematically illustrated by arrows in [Fig.l].

[0066] To avoid overpressure of the enclosure, and to allow a constant flow of incoming air, the interior of the enclosure is exposed to air at a pressure lower than the pressure of the air entering the seals. This air loaded with oil particles, which is evacuated at a pressure well, must first be treated to recover almost all of the oil it carries. For this, the oiled air will be brought to an oil separator which will separate the air from the oil it carries and will reject the de-oiled air outside the engine. This is the principle of de-oiling an enclosure.

[0067] In the present application, the term “line of shafts” means a series of shafts which extend along the same axis and which are rotationally fixed to each other. This line comprises at least two shafts and these shafts are connected together by a coupling device. In the context of the present invention, the couplings between the shafts of the shaft line are of the flex coupling type.

[0068] A coupling device 20 of the flex coupling type is illustrated in Figures 1 and 2 and makes it possible to connect two shafts 8a, 8b.

[0069] In the configuration of [Fig.3], the shaft line comprises three shafts 8a, 8b, 8c which are connected to each other by two coupling devices 20. Shaft 8a is an upstream shaft, shaft 8c is a downstream shaft, and shaft 8b is an intermediate shaft called a coupling shaft.

[0070] Each coupling device 20 is used to ensure the transmission of torque between two shafts of the low pressure shaft line at the input of the reducer 7.

[0071] Figures 4 and 5 represent a more concrete example of embodiment of a coupling device 20.

[0072] The upstream shaft 8a comprises an annular wall 8aa which comprises at its upstream end a toothing 21 for meshing with the sun gear of the reducer 7.

[0073] The downstream end of the wall 8aa is connected to an annular web 22 which extends radially outwards and is connected to an annular flange 24 which itself extends radially outwards. The flange 24 has an axial thickness greater than that of the rest of the web 22 which has a certain flexibility, particularly in bending.

[0074] The downstream shaft 8b comprises an annular wall 8ba whose upstream end is connected to a web 26 which extends radially outwards and is connected to an annular flange 28 which itself extends radially outwards. The flange 28 also has an axial thickness greater than that of the web 26 which has a certain flexibility, particularly in bending.

[0075] The sails 22, 26 each have a radial orientation with respect to the axis A and are substantially parallel and axially spaced from each other by a predetermined distance sufficient to allow the shafts 8a, 8b to work in bending.

[0076] The flanges 24, 28 comprise aligned axial orifices 30 for the passage of screw-nut type fixing means. The screws 32 here have heads bearing axially on a downstream radial face of the flange 28 and receive nuts bearing axially on an upstream radial face of the flange 24.

[0077] The assembly formed by the sails 22, 26, the flanges 24, 28 and the screws 32 form a “flex-coupling” type connection which has a certain flexibility and allows relative movements between the shafts 8a, 8b.

[0078] [Fig.5] shows a three-shaft line 8a, 8b, 8c, as in [Fig.3]. As mentioned above, the shafts 8a, 8b, 8c are respectively an upstream shaft, an intermediate or coupling shaft and a downstream shaft.

[0079] This [Fig.3] illustrates the technique prior to the present invention in which the sails of the trees have perfectly radial orientations, that is to say that these sails extending in planes perpendicular to the axis A, or have classic frustoconicities, that is to say a truncated cone shape which flares out on the side opposite the shaft.

[0080] Thus, the upstream shaft 8a has a web 22 at its downstream end which flares out towards the coupling shaft 8b, i.e. the inner periphery of the web 22 is located upstream of its outer periphery. The coupling shaft 8b has a web 26 at its upstream end which flares out towards the input shaft 8a, i.e. the inner periphery of the web 26 is located downstream of its outer periphery. The coupling shaft 8b has a web 34 at its downstream end which flares out towards the output shaft 8c, i.e. the inner periphery of the web 34 is located upstream of its outer periphery. And the output shaft 8c has a web 36 at its upstream end which flares out towards the coupling shaft 8b, i.e. the inner periphery of the web 36 is located downstream of its outer periphery.

[0081] Figures 6 and 7 illustrate a first embodiment of the invention and [Fig.8] illustrates an alternative embodiment of the invention.

[0082] In Figures 6 and 7, one of the webs 26, 34 of the coupling shaft 8b has an inverted truncated cone and, in [Fig.8], both webs 26, 34 of the coupling shaft 8b have an inverted truncated cone.

[0083] The coupling shaft 8b extends along and around the longitudinal axis A and comprises an annular or tubular wall 8ba which comprises a first longitudinal end connected by a first annular web 34, here downstream, to a first annular flange 38, and a second longitudinal end 26, here upstream, connected by a second annular web 26 to a second annular flange 28.

[0084] Each of the first and second webs 34, 26 has an inner periphery connected to the annular wall 8b 1 and an outer periphery connected to the corresponding flange 38, 28 which extends radially outward from this outer periphery.

[0085] The first web 34 has a general truncated cone shape which flares from its internal periphery to its external periphery on the side of the second web 26. The first web 34 therefore has an inverted truncated cone shape compared to that of [Fig.5].

[0086] The second web 26 has a general truncated cone shape which flares from its internal periphery to its external periphery on the side opposite the first web 34. The second web 26 therefore has a classic truncated cone shape similar to that of [Fig.5].

[0087] As can be seen in Figures 6 and 7, the first web 34 forms an angle α with a plane P1 perpendicular to the axis A and passing through the first flange 38. This angle α is between 1 and 40°, and preferably between 1 and 30°, and is measured in another plane P2 passing through the axis A.

[0088] The second web 26 forms an angle [3 with a plane P3 perpendicular to the axis A and passing through the second flange 28. This angle [3 is between 1 and 40°, and preferably between 1 and 30°, and is measured in the plane P2 passing through the axis A.

[0089] In the example shown, the angles a and [3 are different and in particular inverted due to the inversion of frustoconicity.

[0090] It is also noted in the example shown that each of the sails 26, 34 has a minimum thickness E1 less than a minimum thickness E2 of the wall 8ba.

[0091] The annular wall 8ba comprises an inner annular surface 8bal which is connected by a first radius of curvature RI to a first surface 26a, 34a of each of the webs 26, 34, and an outer annular surface 8ba2 which is connected by a second radius of curvature R2 to a second surface 26b, 34b of each of the webs 26, 34. The radii of curvature RI, R2 at the first web 34 may be different. The radii of curvature RI, R2 at the second web 26 may be different.

[0092] The upstream shaft 8a comprises an annular wall 8aa, a downstream longitudinal end of which is connected by an annular web 22 to an annular flange 24. This web 22 comprises an internal periphery connected to the annular wall 8aa and an external periphery connected to the flange 24 which extends radially outwards from this external periphery.

[0093] The web 22 of this upstream shaft 8a has a generally truncated cone shape which flares from its internal periphery to its external periphery on the side of the coupling shaft 8b. This web 22 therefore has a classic truncated cone shape.

[0094] The veil 22 forms an angle [3 ' with the plane P3, which can be equal to or different from the angle [3.

[0095] The veil 22 may have a minimum thickness less than a minimum thickness of the wall 8aa.

[0096] The upstream shaft 8a may comprise at its upstream end a toothing 21 (herringbone or helical) for meshing with the sun gear of the reducer 7.

[0097] The annular wall 8aa comprises an internal annular surface 8aal which is connected by a first radius of curvature R3 to a first surface 24a of the web 22, and an external annular surface 8aa2 which is connected by a second radius of curvature R4 to a second surface 24b of the web 22. The radii of curvature R3, R4 may be different.

[0098] The flanges 24 and 28 are applied axially against each other and tightened together by screw-nut or similar means, as mentioned above.

[0099] The internal peripheries of the sails 26, 24, which are axially opposite each other, are separated from each other by a distance D3, and the external peripheries opposite these sails are separated from each other by a distance D4. Due to their frustoconicalities, D3 is here greater than D4.

[0100] The downstream shaft 8c comprises an annular wall 8ca, a downstream longitudinal end of which is connected by an annular web 36 to an annular flange 40. This web 36 comprises an internal periphery connected to the annular wall 8ca and an external periphery connected to the flange 40 which extends radially outwardly from this outer periphery.

[0101] The web 36 of this downstream shaft 8c has a generally truncated cone shape which flares from its internal periphery to its external periphery on the side opposite the coupling shaft 8b. This web 22 therefore has an inverted truncated cone, as is the case with its web 34 opposite it.

[0102] The flanges 38, 40 are applied axially against each other and tightened together by screw-nut or similar means, as mentioned above.

[0103] The internal peripheries of the sails 34, 36, which are axially opposite each other, are separated from each other by a distance D1, and the external peripheries opposite these sails are separated from each other by a distance D2. Due to their frustoconicalities, D1 is here less than D2.

[0104] The veil 36 forms an angle a' with the plane PI, which can be equal to or different from the angle a.

[0105] The veil 36 may have a minimum thickness less than a minimum thickness of the wall 8ca.

[0106] The downstream shaft 8c may comprise at its downstream end rectilinear grooves 21' for meshing with another shaft for example.

[0107] The annular wall 8ca comprises an internal annular surface 8cal which is connected by a first radius of curvature R5 to a first surface 36a of the web 36, and an external annular surface 8aa2 which is connected by a second radius of curvature R6 to a second surface 36b of the web 369. The radii of curvature R5, R6 may be different.

[0108] In the embodiment variant of [Fig.8], the coupling device 20 between the coupling shaft 8b and the downstream shaft 8c is identical to that of FIGS. 6 and 7.

[0109] The second web 26 has a generally truncated cone shape which flares from its internal periphery to its external periphery on the side of the web 34. The second web 26 therefore has an inverted truncated cone.

[0110] The second web 26 forms an angle [3 with a plane P3 perpendicular to the axis A and passing through the second flange 28. This angle [3 is between 1 and 40°, and preferably between 1 and 30°, and is measured in the plane P2 passing through the axis A.

[0111] In the example shown, the angles a and [3 may be different or identical.

[0112] The web 26 may have a minimum thickness E1 less than a minimum thickness E2 of the wall 8ba. The radii of curvature RI, R2 of the web 26 may be different.

[0113] The web 22 of the upstream shaft 8a has a generally truncated cone shape which flares from its internal periphery to its external periphery on the side opposite the coupling shaft 8b. This web 22 therefore has an inverted truncated cone.

[0114] The veil 22 forms an angle [3 with the plane P3, which can be equal to or different from the angle [3.

[0115] The veil 22 may have a minimum thickness less than a minimum thickness of the wall 8aa.

[0116] The upstream shaft 8a may comprise at its upstream end a toothing 21 (herringbone or helical) for meshing with the sun gear of the reducer 7.

[0117] The radii of curvature R3, R4 may be different.

[0118] The flanges 24 and 28 are applied axially against each other and tightened together by screw-nut or similar means, as mentioned above.

[0119] The internal peripheries of the sails 26, 24, which are axially opposite each other, are separated from each other by a distance D3, and the external peripheries opposite these sails are separated from each other by a distance D4. Due to their frustoconicalities, D3 is here less than D4.

[0120] In the examples illustrated in the drawings, each coupling device has a support plane for its flanges which is perpendicular to the axis A and which passes substantially between the webs connected to these flanges, whether these webs have a conventional or inverted frustoconical shape.

[0121] Although it is preferable for two sails with classic frustoconical shape to be associated by their flanges, and for two sails with reverse frustoconical shape to be associated by their flanges, it is not impossible to associate a sail with classic frustoconical shape with a sail with reverse frustoconical shape.

[0122] In yet another variant not shown, the coupling device 20 with inverted frustoconicalities of figures 6 and 7 could be upstream of the coupling shaft 8b rather than downstream.

[0123] In operation, the inverted frustoconicalities of the or each coupling device 20 illustrated in Figures 6 to 8 cause an axial extension or expansion of the coupling shaft 8b and the shaft line. This axial extension is able to compensate for the axial displacement imposed by the motor in operation so as to limit or even cancel the risk of axial misalignment of the gear teeth. Naturally, the coupling shaft 8b according to the invention could be used in another context in which it would not necessarily be coupled to a gear, for example.

Claims

Claims

1. Coupling shaft (8b) for an aircraft turbomachine (1), this shaft (8b) extending along and around a longitudinal axis (A) and comprising an annular wall (8ba) which comprises a first longitudinal end connected by a first annular web (34) to a first annular flange (38), and a second longitudinal end connected by a second annular web (26) to a second annular flange (28), each of the first and second webs (26, 34) comprising an inner periphery connected to the annular wall (8ba) and an outer periphery connected to the corresponding flange (28, 38) which extends radially outwards from this outer periphery, characterized in that said first web (34) has a generally frustoconical shape which flares from its inner periphery to its outer periphery on the side of said second web (26).

2. Coupling shaft (8b) according to claim 1, wherein said second web (26) has a generally frustoconical shape which flares from its inner periphery to its outer periphery on the side of said first web (34).

3. Coupling shaft (8b) according to claim 1, wherein said second web (26) has a generally frustoconical shape which flares from its inner periphery to its outer periphery on the side opposite said first web (34).

4. Coupling shaft (8b) according to claim 2 or 3, wherein the second web (26) forms an angle [3 with a plane (P3) perpendicular to the longitudinal axis (A) and passing through the second flange (28), this angle [3 being between 1 and 40°, and preferably between 1 and 30°, and being measured in another plane (P2) passing through the longitudinal axis (A).

5. Coupling shaft (8b) according to one of the preceding claims, in which the first web (34) forms an angle α with a plane perpendicular to the longitudinal axis (A) and passing through the first flange (38), this angle α being between 1 and 40°, and preferably between 1 and 30°, and being measured in another plane (P2) passing through the longitudinal axis (A).

6. A coupling shaft (8b) according to claim 5 when dependent on claim 4, wherein the angles a and [3 are different.

7. A coupling shaft (8b) according to claim 5 when dependent on claim 4, wherein the angles a and [3 are the same.

8. Coupling shaft (8b) according to one of the preceding claims, wherein each of said first and second webs (26, 34) has a minimum thickness (El) less than a minimum thickness (E2) of said wall (26, 34).

9. Coupling shaft (8b) according to one of the preceding claims, wherein the annular wall (8ba) comprises an inner annular surface (8ba) which is connected by a first radius of curvature (RI) to a first surface (26a, 34a) of each of the webs (26, 34), and an outer annular surface (8ba2) which is connected by a second radius of curvature (R2) to a second surface (26b, 34b) of each of the webs (26, 34), the first and second radii of curvature (RI, R2) at the first web (34) being different and / or the first and second radii of curvature (RI, R2) at the second web (26) being different.

10. Aircraft turbomachine (1), comprising three shafts (8a, 8b, 8c) extending along and around a longitudinal axis (A) and rotationally integral around this axis, these three shafts (8a, 8b, 8c) comprising: - an upstream shaft (8a) comprising an annular wall (8aa) of which a downstream longitudinal end is connected by an annular web (22) to an annular flange (24), this web (22) comprising an internal periphery connected to the annular wall and an external periphery connected to the flange (24) which extends radially outwards from this external periphery, - a downstream shaft (8c) comprising an annular wall of which an upstream longitudinal end is connected by an annular web (36) to an annular flange (40), this web (36) comprising an internal periphery connected to the annular wall and an external periphery connected to the flange (40) which extends radially outwards the outside from this external periphery,and - a coupling shaft (8b) according to one of the preceding claims interposed between the upstream and downstream shafts (8a, 8c), the flanges (28, 38) of the coupling shaft (8b) being respectively fixed to the flanges (24, 40) of the upstream and downstream shafts (8a, 8c).,

11. Turbomachine (1) according to claim 10, in which: - the first flange (38) is fixed to the flange (24) of the upstream shaft (8a), the web (22) of this upstream shaft (8a) having a generally frustoconical shape which flares from its internal periphery to its external periphery on the side opposite the coupling shaft (8b), or - the first flange (38) is fixed to the flange (40) of the downstream shaft (8c), the web (36) of this downstream shaft (8c ... side opposite the coupling shaft (8b).

12. Turbomachine (1) according to claim 11, in which the internal peripheries of the first web (34) and of the web (22, 36) facing the upstream or downstream shaft (8a, 8c) are separated from each other by a distance D1, and the external peripheries of the first web (34) and of the web (22, 26) facing the upstream or downstream shaft (8a, 8c) are separated from each other by a distance D2, D1 being less than D2.

13. Turbomachine (1) according to one of claims 10 to 12, the coupling shaft (8b) being as defined in claim 2, in which: - the second flange (28) is fixed to the flange (40) of the downstream shaft (8c), the web (36) of this downstream shaft (8c) having a generally frustoconical shape which flares from its internal periphery to its external periphery on the side opposite the coupling shaft (8b), or - the second flange (28) is fixed to the flange (24) of the upstream shaft (8a), the web (22) of this upstream shaft (8a) having a generally frustoconical shape which flares from its internal periphery to its external periphery on the side opposite the coupling shaft (8b).

14. Turbomachine (1) according to one of claims 10 to 12, the coupling shaft (8b) being as defined in claim 3, in which: - the second flange (28) is fixed to the flange (40) of the downstream shaft (8c), the web (36) of this downstream shaft (8c) having a generally frustoconical shape which flares from its internal periphery to its external periphery on the side of the coupling shaft (8b), or - the second flange (28) is fixed to the flange (40) of the upstream shaft (8a), the web (22) of this upstream shaft (8a) having a generally frustoconical shape which flares from its internal periphery to its external periphery on the side of the coupling shaft (8b).

15. Turbomachine (1) according to one of claims 10 to 14, in which the downstream shaft (8c) is a turbine shaft or coupled to a turbine shaft, and the upstream shaft (8a) is an input shaft of a mechanical reducer (7) or coupled to such an input shaft, the reducer (7) comprising a flexible output coupled to a propeller shaft.

Images