Method for assembling an epicyclic or planetary gear train

Abstract

The invention discloses a method for assembling an epicyclic gear train or a planetary gear train of a planetary gear carrier, the planetary gear carrier comprising one or more holes, each hole being for receiving a pivot (18), the method comprising the following steps: a) manufacturing at least one pivot (18) comprising a real axis (46) different from a theoretical axis; b) measuring the position of the real axis of each of the one or more holes (34) of the carrier; c) for each hole of the carrier, mounting the pivot (18) in the hole and orienting it at an angle such that the eccentricity of the pivot (18) at least partially compensates for the eccentricity of the hole.

Description

Technical Field

[0001] The invention relates to a method for assembling an epicyclic or planetary gear train for equipping a turbine engine, such as a turbojet engine or an aircraft turboprop engine. Background Art

[0002] A turbine engine may include a gear train that connects its turbine shaft to one or more output elements, such as a blower. This type of gear train includes inner planetary gears (also called sun gears) driven by an input shaft, such as the turbine shaft, outer planetary gears (also called ring gears) coaxial with the sun gear, the planetary gears meshing with both the sun gear and the ring gear, and a carrier on which the planetary gears are rotatably mounted. The planetary gears are movably and rotatably mounted on pivots that are inserted into holes in the carrier.

[0003] In certain configurations, a gear train can reduce the speed between the input and output of the gear train. Varying the reduction ratio of such a gear train is achieved by varying the number of teeth on the sun, planetary, and ring gears, as well as by the gearbox's design, either epicyclic or planetary. These two types of gear trains differ in that, in so-called epicyclic gear trains, the ring is fixed and the carrier is free to rotate. In contrast, in so-called planetary gear trains, the carrier is fixed and the outer gear or ring gear is free to rotate.

[0004] In the case of these two types of gear trains, there is a difference in the power transmitted through the planetary gears of the carrier, and this difference may cause excessive mechanical stress to be applied to some of the planetary gears.

[0005] According to the ANSI / AGMA 6123-B06 standard established by the American Gear Manufacturers Association (AGMA), under actual operating conditions, the overload of each planet gear of an epicyclic gear train or a planetary gear train must be approximately 12%.

[0006] One of the reasons for this discrepancy is the relative positioning errors of the planetary gears, in particular the relative tangential positioning errors of the planetary gears relative to each other about the carrier axis. In addition, the misalignment of the planetary gear teeth with the teeth of the sun gear and the ring gear leads to premature wear of the teeth, requiring regular maintenance and increasing the operating costs of the turbine engine.

[0007] One solution to reducing this overload phenomenon in current technology is to pair the planetary gear-supporting pivots and the carrier's holes during component processing and assembly. This pairing involves defining pivot-hole pairs so that the pivots and holes of a pair are assembled together. One consequence of this pairing is that the two pairs of pivots are not interchangeable.

[0008] Pairing makes it more complicated to manage component inventory when assembling or maintaining the epicyclic gear train. In addition, pairing operations are limited because they require complex pre-assembly tasks for assembling the bracket assembly, which leads to high production costs and makes maintenance operations more complicated.

[0009] One of the main purposes of the present invention is to reduce the planet gear positioning errors in the carrier in a simple, effective and economical way by applying a specific pivot design and without having to use mating. Summary of the Invention

[0010] Firstly, the invention relates to a method for assembling an epicyclic or planetary gear train comprising a carrier comprising one or more holes, each hole being intended to receive a pivot shaft, the method comprising the following steps:

[0011] a) producing at least one pivot comprising a real axis different from a theoretical axis;

[0012] b) measuring the position of the real axis of each of the one or more holes of the bracket;

[0013] c) For each hole of the bracket, install a pivot in the hole and rotate it at an angle so that the offset of the pivot

[0014] The center at least partially compensates for the eccentricity of the hole.

[0015] Positional defects of the holes on the bracket and concentricity defects of the pivot lead to tangential deviations of the real axis from the theoretical axis. Typically, due to hole tolerances and possible manufacturing defects, each of these holes has a real axis that is different from the theoretical axis.

[0016] Thus, although each pivot and hole each has a real axis (ie an actual axis) that is eccentric relative to its theoretical axis, the assembly according to the method of the invention makes it possible to minimize the eccentricity of the shaft caused by the pivot-hole assembly.

[0017] During assembly step c), the pivot is oriented in the bracket in such a way that the eccentricity of the pivot at least partially compensates the eccentricity of the hole, allowing the eccentricities of the actual axes of the pivot and of the hole to partially compensate each other.

[0018] Orientation of the components during assembly then makes it possible to correct relative tangential position defects between the planet gears and thus reduce overloading phenomena of the planet gears, pivots and holes, without changing the manufacturing tolerances of the carrier holes and pivots.

[0019] Thus, every pivot is compatible with every hole, as long as the proper angle of the pivot in the hole is oriented when installed.

[0020] The method does not require pairing and also allows the interchangeability of parts during assembly or maintenance operations.Thus, regardless of the pivot installed in a specific hole and the orientation of the pivot in the hole, the method according to the invention allows the defects caused by the pivot-hole assembly to be reduced.

[0021] Due to better control over the manufacturing of the pivot and its raceways, concentricity defects in the pivot are statistically less important than position defects in the holes in the bracket, so in some cases defects in the pivot may not be sufficient to compensate for positioning defects in the holes in the bracket.

[0022] In order to ensure at least partial systematic compensation of the real axes of the pivot and the hole, the method according to the invention proposes a step of manufacturing the pivot with a controlled eccentricity of its real axis before assembly.

[0023] Thus, step a) of the method according to the invention may comprise:

[0024] - Manufacturing at least one pivot, comprising:

[0025] at least one raceway, the axis of which coincides with the actual axis of the pivot, and

[0026] At least one shrink-fit seat of the pivot in the hole, the axis of which coincides with the theoretical axis of the pivot.

[0027] The eccentricity of the real axis relative to the theoretical axis is controlled during the manufacture of the pivot according to the invention by varying the axis of rotation of its raceway, which axis of rotation is usually confused with the axis of the shrink fit, without any eccentricity defects in the real axis of the pivot.

[0028] Thus, by introducing an eccentricity between the raceway and the shrink-fit seat of the pivot, minimal imperfections of the pivot are ensured, allowing its effective use in the assembly process according to the invention.

[0029] Step a) may further comprise the following steps:

[0030] - dividing each of said pivots into n angular sectors i1 ... i extending around the theoretical axis of said pivot q …i n ;

[0031] - Defines the vector oriented from the theoretical axis to the real axis and identify vectors including Angular sector i q .

[0032] Step c) may further comprise the following steps:

[0033] i) dividing each of the planet carrier bores into k angular sectors j1 ... j extending around the theoretical axis of the bore l …jk ;

[0034] ii) For each hole, define a vector oriented from the theoretical axis to the real axis and identify vectors including Angular sector j l ;

[0035] iii) For each hole of the bracket, install the pivot so that for each installation, the identified angular sector j l and i q are superimposed.

[0036] During assembly step iii), the pivot is oriented in the bracket so that the identified sectors overlap and therefore the vector and Not being arranged in the same angular sector allows the eccentricity of the pivot and the actual axis of the hole to be partially compensated.

[0037] In addition, the bracket can carry the first connecting device, and the pivot can carry the first connecting device. q The second connecting device in the region comprises an opening having a shape adapted to cooperate with the first connecting device. The first and second connecting devices are form-fitting connecting devices, which may also be referred to as positive engagement connecting devices.

[0038] Furthermore, according to the invention, the opening can be formed in a radial growth carried by the pivot shaft.

[0039] This makes it easy to deduce the angular sector i in which the actual axis of the pivot is located. q .

[0040] According to one characteristic of the invention, the first connection means may comprise a device arranged in the angular sector j l The first protruding member in the first hole can be arranged in k holes, each arranged around the hole and in the angular sectors j1...j l …j k wherein step ii) may further comprise the following steps:

[0041] - Insert the first component into the corner sector j l In the lth hole.

[0042] Therefore, each hole includes a hole carried by the planet gear carrier and located at a position including the vector Angular sector j l The member in the pivot includes a radial growth E, which includes an opening capable of cooperating with the member. The radial growth E is located at a position including the vector Angle sector i qIn this way, the angular sectors j of each hole and each pivot, respectively, can be visually identified. l and i q It is easier to deduce the angular sector in which the actual axis of the hole and the pivot are located.

[0043] Step (iii) may further comprise the following steps:

[0044] - Orienting the pivot so as to insert the first element carried by the bracket into the radially enlarged E opening carried by the pivot.

[0045] Therefore, by installing the pivot so that the member is inserted into the remaining radial growth E of the pivot q of the opening, ensure that the pivot is mounted in the hole by orienting it so as to align with the identified angular sectors j of the hole and pivot respectively l and i q overlapping.

[0046] By superimposing the angular sector j l and i q , vector and Not being arranged in the same angular sector means that position errors of the pivot and the real axis of the hole at least partially compensate for each other.

[0047] Furthermore, when the pivot is installed in the hole, the member and radial growth E q The fit of the opening reduces orientation errors.

[0048] This approach is an industrially viable solution that also avoids mating the planet carrier's holes with the associated pivot shafts.

[0049] The pivot and the hole are divided into n and k angular sectors respectively, so that n can be greater than or equal to k.

[0050] Therefore, when n is strictly higher than k, the position of the real axis on the pivot is more accurately identified, while simultaneously avoiding the need to divide the hole into as many angular sectors as possible. As mentioned above, each angular sector of the hole consists of holes arranged around the perimeter of the hole in the planet gear carrier. Such a large number of holes in the carrier could lead to mechanical weakening. Therefore, by limiting the number of angular sectors k, so that n is greater than k, the mechanical weakening of the planet gear carrier caused by the formation of holes is reduced and better controlled.

[0051] For this purpose, n and k may be between 3 and 8, inclusive.

[0052] The invention also relates to an epicyclic or planetary gear train obtainable by a method as described above.

[0053] Furthermore, the invention relates to an epicyclic gear train comprising one or more holes, each receiving a pivot comprising a real axis different from a theoretical axis, said pivots being oriented at an angle such that the eccentricity of the pivots at least partially compensates for the eccentricity of said holes.

[0054] This epicyclic gear train thus has minimal eccentricity of the axis caused by the pivot-bore assembly. By orienting the pivot in the bore of the epicyclic gear train, the latter has less overloading of the planetary gears of the pivot and bore without changing the manufacturing tolerances of the carrier bore and the pivot.

[0055] Furthermore, the assembly of such a gear train does not require pairing, thus allowing the interchangeability of components during assembly or maintenance operations. Thus, the method according to the invention allows the reduction of defects caused by pivot-hole sets, regardless of the pivot installed in a particular hole and the orientation of the pivot in the hole.

[0056] According to one feature of the invention, the pivot of the epicyclic gear train may comprise:

[0057] - at least one raceway, the axis of which coincides with the actual axis of the pivot, and

[0058] - at least one shrink-fit seat of the pivot in the hole, the axis of which coincides with the theoretical axis of the pivot.

[0059] The pivot used during assembly is produced by ensuring a controlled eccentricity of the actual axis relative to the theoretical axis.

[0060] Additionally, the aperture and pivot may respectively include first and second coupling means adapted to mate together to retain the pivot in a predetermined orientation within the aperture, the second coupling means including an opening shaped to receive the first coupling means.

[0061] For example, the first connection means may comprise a protruding member.

[0062] Furthermore, an opening may be formed in a radial growth of the pivot bearing and may be adapted to receive said protruding member.

[0063] The hole and the pivot connection means can be arranged respectively on a vector oriented from the theoretical axis to the real axis. The angular sector of and including the vector In the angular sector of Oriented from the theoretical axis to the real axis.

[0064] The invention also relates to an epicyclic or planetary gear train obtainable by a method as described above.

[0065] Additionally, such a gear train may comprise one or more holes, each hole receiving a pivot shaft comprising a real axis different from a theoretical axis, said pivot shafts being oriented at an angle such that an eccentricity of the pivot shaft at least partially compensates for an eccentricity of said hole.

[0066] In particular, the pivot may comprise:

[0067] - at least one raceway, the axis of which coincides with the actual axis of the pivot, and

[0068] - at least one shrink-fit seat of the pivot in the hole, the axis of which coincides with the theoretical axis of the pivot.

[0069] The epicyclic gear train may include a planetary gear carrier having a hole, with the pivot being arranged in the hole, and the hole and the pivot may respectively include first and second connecting means that can be matched together to maintain the pivot in a predetermined orientation in the hole, and the second connecting means may include an opening having a shape suitable for receiving the first connecting means.

[0070] Additionally, the first connecting means may comprise a protruding member.

[0071] Furthermore, an opening may be formed in the radial growth E carried by the pivot shaft and may be adapted to receive said protruding member.

[0072] According to another feature of the invention, the holes and the pivot connection means can be arranged respectively on a line including a vector oriented from the theoretical axis to the real axis. and including the vector oriented from the theoretical axis to the real axis and in the angular sector.

[0073] The invention will be better understood and other details, characteristics and advantages of the invention will emerge on reading the following description given as a non-limiting example with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] - Figure 1 is a schematic front view of the gear train from the upstream axis;

[0075] - Figure 2 It is a schematic diagram of a turbine engine;

[0076] - Figure 3 is a schematic diagram of a planetary gear carrier according to the present invention;

[0077] - Figure 4 is a cross-sectional view of the pivot shaft mounted in the hole of the planetary gear carrier;

[0078] - Figure 5 is a perspective view of a pivot shaft manufactured in accordance with the present invention;

[0079] - Figure 6 is a diagram illustrating a cross-sectional view of a pivot manufactured by the method according to the present invention;

[0080] - Figure 7a and 7b The assembly step c) of the method according to the present invention is respectively illustrated;

[0081] - Figure 8 is a schematic diagram of a gear train obtainable by the method according to the invention. DETAILED DESCRIPTION

[0082] Figure 1 The structure of an epicyclic or planetary gear train 10 is schematically shown. This type of gear train 10 typically includes an internal gear 12 (also known as a central pinion, sun, or sun gear) and an external gear 14 (also known as a ring gear), the two gears being coaxial. Sun gear 12 is rotatable about its axis X, and ring gear 14 can be fixedly or rotatably connected to a propeller, such as in the case of a twin-flow turbojet engine, or a turboprop or blower impeller. Gear train 10 also includes planet gears 16 rotatably mounted on pivots 18 of a planet gear carrier 20. Each planet gear 16 meshes with both sun gear 12 and ring gear 14. Planet gear carrier 20 is either fixed or rotatable about axis X of sun gear 12 and ring gear 14. The inlet can be formed by sun gear 12, and the outlet by planet gear carrier 20.

[0083] In another embodiment, the bracket 20 may be fixedly or rotatably connected to a propeller of a turboprop engine or a blower wheel of a twin-flow turbojet engine.

[0084] Figure 2 An aircraft turbine engine 22 is schematically shown, in which the gear train 10 is used as a speed reducer to reduce the rotational speed of a rotor, for example a blower wheel 24, independently of the rotational speed of at least one turbine 26 axially connected downstream to at least one compressor 28, to which the turbine engine is also equipped. Starting from a front air inlet 30, the air then passes through the blower wheel 24 and the compressor 28.

[0085] The central pinion or sun gear 12 surrounds and is then rotationally fixed to the shaft 32 of the compressor 28, e.g., Figure 1 and Figure 2 In particular, Figure 2 As shown, the gear train 10 may be mounted in a radially formed annular chamber within a low pressure compressor 28a disposed downstream of the blower wheel 24 and upstream of the high pressure compressor 28b.

[0086] As from Figure 1As can be seen in FIG, alignment of the planet gears with the sun gear 12 and the ring gear 14 is essential for proper operation of the gear train 10 and to limit maintenance operations.

[0087] Incorrect positioning of the planet gear 16 in the hole 34 of the carrier 20 (in Figure 3 ) causes the teeth of the planet gears 16 to be misaligned with the teeth of the sun gear 12 and the teeth of the ring gear 14. This results in a difference in the power transmitted through the planet gears 16, which causes early wear of the teeth.

[0088] Therefore, it is necessary to provide a solution to minimize misalignment of the planetary gears 16 when assembling such a gear train 10 .

[0089] For this purpose, Figure 7a and 7b As partially shown in FIG, an assembly method is proposed for the gear train 10. The mounting can be performed from at least one pivot manufactured according to the steps of the assembly method and a bracket 20 comprising one or more holes 34.

[0090] Figure 3 An embodiment of a planetary gear carrier 20 according to the invention is shown, in which the epicyclic gear train is assembled. It has five holes 34 that are regularly distributed around the X axis and are dimensioned so that the pivot shaft 18 can be mounted therein.

[0091] Figure 5 An embodiment of a pivot shaft made in accordance with the present invention is shown in FIG. The pivot shaft 18 comprises a shaft 36 having a diameter sized so as to be disposed in the bore 34 of the planetary gear carrier. The shaft 36 is generally cylindrical or frustoconical in shape and extends at one end by an annular connecting portion 38 extending radially outwardly ( Figure 4 ).

[0092] The pivot 18 also comprises shrink-fit seats 40 located in the hole 34. Since the pivot 18 will be shrunk at these shrink-fit seats 40 in one of the holes 34 of the bracket 20, the shrink-fit seats 40 of the pivot 18 in the hole 34 correspond to the annular surface of the shaft 36 of the pivot 18, said seats being intended to be in close contact with at least a portion of the hole 34 of the bracket 20. Thus, as Figure 4 As shown, when the pivot 18 is mounted in the hole 34 of the bracket 20 , the shrink-fit seat 40 of the pivot 18 contacts a portion of the inner annular surface of the hole 34 over its entire surface.

[0093] The pivot shaft 18 also includes raceways 42 to receive bearings for rotating the planetary gears 16 ( Figure 1 The planetary gears are meshed with the sun gear 12 and the ring gear 14 at the same time, as shown in FIG. Figure 1 shown.

[0094] exist Figure 4 The mounting of the pivot 18 in the hole can also be seen in FIG. The axis 36 of the pivot 18 is arranged in the hole 34 of the bracket 20 so that the connecting portion 38 rests on the surface 44 of the bracket 20 on the periphery of the hole 34.

[0095] exist Figure 7a and 7b In the embodiment shown, the method is applied to two holes 34 of one and the same bracket 20 or two separate brackets 20 , and to two pivots 18 , manufactured according to the first step of the assembly method.

[0096] The first step of the method comprises the step of producing at least one pivot 18 comprising a real axis 46 different from the theoretical axis 48. An embodiment of the pivot 18 obtained by this first method step is Figure 5 and Figure 6 Shown in.

[0097] When the pivot 18 has no defects, i.e. when its real axis 46 and its theoretical axis 48 are confused, this means that the shrink-fit seat 40 and the raceway 42 are coaxial, with the theoretical axis 48 of the pivot 18 as the real axis. Thus, the manufacturing step aimed at producing a pivot 18 with controlled defects aims at producing a pivot 18 in which at least one raceway 42 and at least one shrink-fit seat 40 of the pivot 18 in the hole 34 are not coaxial.

[0098] In particular, the pivot 18 is manufactured in such a way that it comprises at least one shrink-fit seat 40 of the pivot 18 in the hole 34, the axis of rotation of which coincides with the theoretical axis 48 of the pivot 18. Furthermore, at the same time, the pivot 18 is manufactured in such a way that it comprises at least one raceway 42, the axis of rotation of which coincides with the actual axis 46 of the pivot 18.

[0099] Figure 6 An embodiment of a pivot 18 obtained by the first method step according to the invention is shown. The actual axis 46, corresponding to the rotational axis of the two raceways 42, is eccentric relative to the theoretical axis 48, which corresponds to the rotational axis of the two shrink-fit seats 40 of the pivot 18 in the bore 34. The dashed line 50 corresponds to the position of the raceways 42 of a flawless pivot 18, whose rotational axis coincides with the theoretical axis 48 of the pivot 18 and which the shrink-fit seat 40 of the pivot 18 in the bore 34 of the bracket 20 should have.

[0100] Therefore, in order to shift the axis of rotation of the raceway 42, when the pivot 18 is machined, for example by turning, the axis along which the component is rotated to remove material to form the raceway 42 and the shrink fit seat 40 is shifted relative to the machining axis of the shrink fit seat 40 when the raceway 42 is machined.

[0101] Thus, when machining a component, the offset of the axis about which the component rotates allows the positioning of the actual axis 46 to be controlled and known.

[0102] The manufacturing step also includes a first step of characterizing the relative known position of the real axis 46 of the manufactured pivot 18 relative to its theoretical axis 48. This position is characterized by the vector It is oriented from the theoretical axis 48 of the manufactured pivot 18 to the actual axis 46, as shown Figure 7a and 7b shown.

[0103] For each pivot 18 made, define the vector Vector The vector is oriented from the theoretical axis 48 of the manufactured pivot 18 to the real axis 46 and its standard is equal to the distance between the theoretical axis 48 and the real axis 46 of the manufactured pivot 18. In other words, the vector is oriented from the real axis 46 to the real axis 46 of the manufactured pivot 18. This corresponds to the translation of the axis about which the pivot 18 rotates when the raceway 42 is machined.

[0104] In a practical embodiment, compatible with the industrialization of the component, the manufacturing step also comprises a step consisting in regularly dividing each pivot 18 manufactured into several identical angular sectors around their respective theoretical axis 48. Thus, each pivot 18 is divided into n angular sectors i1 . . . i extending around the theoretical axis 48 of the pivot 18 considered. q …i n .

[0105] This division into angular sectors makes it possible to locate in which angular sector of the component lies the vector and thus the real axis 46 of the manufactured pivot 18. In particular, another step in the manufacturing process is to identify the axis comprising the vector Angular sector i q .

[0106] The second step of the assembly method is to measure the position of the real axis 52 of each hole 34 of the bracket 20. Each hole thus has a real axis 52 that is different from the theoretical axis 54. Figure 7a As shown in , the measurement in this first step provides the positioning of the real axis 52 relative to the theoretical axis 54 of each hole 34 .

[0107] The eccentricity of the real axis 52 relative to the theoretical axis 54 of the bore 34 is due in part to manufacturing imperfections, particularly the positioning of the bore 34 in the bracket 20 .

[0108] The three-dimensional position measurement of the real axis 52 of the holes 34 is carried out using a dedicated machine. This machine, by palpation of the circumference of each hole 34, allows the actual position of the center, and therefore the real axis 52 of the hole 34, to be determined by calculation.

[0109] Once the positions of the real axes 52 of the manufactured pivots 18 and of the holes 34 of the bracket 20 are known, the third step of the assembly method aims at installing, for each hole 34 of the bracket 20, one manufactured pivot 18 in the hole 34, oriented at an angle such that the eccentricity of the pivot 18 at least partially compensates for the eccentricity of said hole 34. The eccentricity is understood to be the eccentricity of the real axes 46, 52 of the manufactured pivot 18 and of the hole 34 relative to the theoretical axes 48, 54.

[0110] In order to allow compensation for these eccentricities of the pivot 18 and of the hole 34 receiving it, the third step of the assembly process consists in a first step of characterizing the relative known position of the solid axis 52 of the hole 34 with respect to its theoretical axis 54. This position is characterized by the vector It is oriented from the theoretical axis 54 of the hole 34 to the real axis 52, as shown Figure 7a and 7b shown.

[0111] For each hole 34, define the vector Vector It is oriented from the theoretical axis 54 to the real axis 52 and its norm is equal to the distance between the theoretical axis 54 and the real axis 52 of the hole 34 .

[0112] In a practical embodiment compatible with the industrialization of the component, the method comprises a second step consisting in regularly and independently dividing the manufactured pivot 18, dividing the holes 34 of the bracket 20 into several equal angular sectors around their theoretical axis 54. Thus, the holes 34 are independently divided into a regular number of k angular sectors j1 ... j extending around their theoretical axis 54. l …j k .

[0113] Thus, the pivot 18 and hole 34 are manufactured to be divided into n and k sectors respectively, where n and k can be equal, as Figure 7a and 7b As shown, where n=k=4.

[0114] The division of the aperture 34 into angular sectors makes it possible to locate the vector The angular sector of the portion and thus the real axis 52 of the hole 34 is located. In particular, the steps in the manufacturing method are aimed at identifying the vector Angular sector j l .

[0115] On this basis, the third step of the assembly method includes Figure 7b The additional step shown in , which is intended to install a manufactured pivot 18 in the hole 34 and orient it angularly in the hole so that, for each assembly, the identified angular sector j l and iq In other words, the pivot 18 is manufactured and installed and oriented in a hole 34 so that the vector and V → The real axis 46 of the pivot 18 of the defined assembly and the real axis 52 of the hole 34 at least partially offset each other.

[0116] like Figure 7b As shown, the pivot 18 can be installed in any of the holes 34. However, during assembly, the pivot 18 is installed in such a manner that the vector and are not in the same angular sector, i.e. such that the identified angular sector j l and i q It's superimposed.

[0117] This method requires no mating parts, so the pivot 18 can be installed in all holes 34 as long as the orientation of the pivot 18 is respected.

[0118] In practice, the third step of the assembly method is performed by means of a positioning device. The positioning device comprises additional connection means on the pivot 18 and on the bracket 20. The positioning device allows the pivot 18 to be oriented and fixed in the desired orientation during assembly. In practice, as will be understood below, this device performs error-proofing when installing the pivot 18 in the hole 34, preventing the pivot 18 from being improperly installed in the hole 34, which would lead to the opposite of the desired result, namely, increased tooth misalignment.

[0119] like Figure 7a and 7b As shown, the connection means comprise first form-fit connection means carried by the bracket 20. These first connection means comprise first members 56 which can be placed in a protruding position in holes 62 arranged around the periphery of the holes 34. In particular, the holes 62 are arranged so that there is only one hole 62 for each angular sector of each hole 34 of the bracket 20, as shown in FIG. Figure 3 shown.

[0120] For each hole 34, once the angular sector j is identified l , the first member 56 is placed at a position including the vector and the angular sector j of the real axis 52 l Hole 62 in the middle.

[0121] Thus, for each hole 34, this step makes it possible to clearly see the angular sector in which the real axis 52 of the hole 34 is located and where there are available connection means that will then help to "orient" a manufactured pivot 18 in the hole 34, i.e. in the angular position that leads to reduced tooth misalignment. Figure 7b, which partially illustrates this step, the pin 56 is arranged in a vector including the two holes 34 In the angular sectors j2 and j4.

[0122] like Figure 5 、 7a As shown in FIG7b, the connection device further comprises a second form-fit connection device carried by the pivot 18, and the pivot 18 has a shape suitable for cooperating with the first form-fit connection device. The first and second form-fit connection devices can also be referred to as first and second form-engaging connection devices. For example, the second form-fit connection device comprises an opening 58, so that the first member 56, such as the pin 56 carried by the bracket 20, can be arranged in the opening 58. Specifically, as shown in FIG7b, the second form-fit connection device further comprises a second form-fit connection device. Figure 5 As shown, each pivot has openings 58 arranged around the circumference 60 of the pivot 18. Figure 7a and 7b In the embodiment of the present invention, the openings of the two pivots 18 are formed in a radial extension E of the circumference of the pivot 18 , which is arranged on the periphery of the connecting portion 38 of the pivot 18 .

[0123] The second connection means is designed during the manufacturing step of the pivot 18. In particular, during the manufacturing of the pivot 18, the opening 58 or the radial extension E of the opening 58 is machined so as to be arranged in a direction including the vector Angular sector i q This allows each pivot 18 to be visually identified in an angular sector located in the opposite direction of the angular sector in which the real axis 46 of the pivot 18 is located, and provides a connection means that will facilitate the "directional" installation of the pivot 18 in the hole 34. At the end of the manufacture of the pivots 18, each pivot 18 has a single opening 58 or a single radial extension E including the opening 58, as shown Figure 5 and 7a shown.

[0124] Therefore, when the opening of radial growth E is installed in the sector j l When the component is in the form of a pivot 18, the opening 58 or the radial growth E of the opening 58 including the manufactured pivot 18 constitutes a foolproofing device.

[0125] like Figure 7b As shown, the pin 56 carried by the bracket 20 and the opening 58 carried by the pivot 18 make it possible to identify the vector directly or indirectly. and position and orientation.

[0126] Therefore, in a practical embodiment of the method, the third step also comprises the step of orienting the pivot 18 when the pivot is mounted in a hole so as to insert the first protruding member 56 carried by the bracket 20 into the opening 58 of radial enlargement E carried by the pivot 18. Figure 7b As shown, pivot 18 is oriented in hole 34 so that pin 56 of hole 34 cooperates with radially enlarged opening 58 of pivot 18 to ensure that real axis 46 of pivot 18 and real axis 52 of hole 34 are not located in the same angular sector.

[0127] By superimposing a visually identified angular sector j on each hole 34 and pivot 18 l and i q , ensure that during assembly, and The arrangement is such that the real axis 46 of the pivot 18 of the assembly and the real axis 52 of the hole 34 at least partially compensate for one another.

[0128] like Figure 8 As shown, this method produces an epicyclic gear 70 using the cooperation between the radially enlarged E opening 58 of the pivot shaft 18 and the pins 56 arranged around the hole 34 in which the pivot shaft 18 is oriented.

[0129] like Figure 7b As shown, the pivots 18 are interchangeable: they can be mounted in both holes 34 as long as the pivots 18 are correctly oriented using their radial extension E.

[0130] In the specific case of a hole, the vector Located on the boundary between two angular sectors, one of the two sectors is randomly selected as the containing vector Similarly, for the pivot, when the vector When located on the boundary between two angular sectors, one of the two sectors is randomly selected as the inclusion vector According to one embodiment of the invention, the pivot 18 and the hole 34 are divided into n and k angular sectors, respectively, such that n may be greater than or equal to k.

[0131] According to another implementation, n and k may be between 3 and 8, inclusive.

[0132] In particular, by limiting the number of angular sectors of the hole 34, the number of holes 62 on the periphery of the hole 34 on the bracket is also limited. This makes it possible to limit and control the weakening of the bracket 20 through the holes 62.

Claims

1. A method for assembling an epicyclic gear train or a planetary gear train (70) for assembling a planetary gear carrier (20), the planetary gear carrier comprising one or more holes (34), each hole (34) being adapted to receive a pivot shaft (18), the method comprising the following steps: a) manufacturing at least one pivot (18) comprising a real axis different from a theoretical axis, said manufacturing comprising; at least one raceway (42) intended for receiving a bearing for rotating the planetary gear (16), the axis of at least one raceway coinciding with the real axis of the pivot (18), and at least one shrink-fit seat (40) of the pivot (18) in the hole (34), the axis of which coincides with the theoretical axis of the pivot (18); b) measuring the position of a real axis of each of the one or more holes (34) of the bracket (20); the real axis of each of the one or more holes (34) being different from a theoretical axis of each of the one or more holes (34); c) for each hole (34) of the bracket (20), mounting a pivot (18) in said hole (34) and orienting it at an angle such that the eccentricity of the pivot (18) at least partially compensates for the eccentricity of said hole (34); Wherein step a) further comprises the following steps: - dividing each of said pivots (18) into n angular sectors i1 ... i extending around the theoretical axis of said pivot (18) q …i n ; - Defines the vector oriented from the theoretical axis to the real axis and identify vectors including Angular sector i q .

2. The assembly method according to claim 1, wherein step c) comprises the following steps: i) dividing each of the holes (34) of the bracket (20) into k angular sectors j1 . . . j extending around the theoretical axis of the hole l …j k ; ii) For each hole, define a vector oriented from the theoretical axis to the real axis and identify vectors including Angular sector j l ; iii) For each hole (34) of the bracket (20), the pivot (18) is mounted so that for each mounting, the identified angular sector j l and i q are superimposed.

3. Assembly method according to claim 2, wherein the bracket (20) carries the first connecting means and the pivot (18) carries the first connecting means arranged in sector i q The second connecting device comprises an opening (58) having a shape suitable for cooperating with the first connecting device.

4. Assembly method according to claim 3, wherein the opening (58) is formed in a radial extension E carried by the pivot (18).

5. Assembly method according to claim 4, wherein the first connecting means comprises a plurality of connecting members arranged in the angular sector j. l The first protruding member (56) in the embodiment of the present invention can be arranged in k holes (62), each hole being arranged around the hole (34) and in the angular sectors j1...j l …j k wherein step ii) further comprises the following steps: - Insert the first protruding member (56) into the l In the lth hole (62).

6. The assembly method according to claim 5, wherein step (iii) further comprises the following steps: - Orienting the pivot (18) so as to insert the first member (56) carried by the bracket (20) into the radially enlarged E opening (58) carried by the pivot (18).

7. Assembly method according to one of claims 2 to 6, wherein n is greater than or equal to k and / or n and k are between 3 and 8, inclusive.

8. An epicyclic gear train (70) obtained by the method according to one of claims 1 to 6.

9. An epicyclic gear train (70) comprising one or more holes (34), each hole (34) receiving a pivot shaft (18) comprising a real axis different from a theoretical axis, the pivot shaft (18) being oriented at an angle such that an eccentricity of the pivot shaft (18) at least partially compensates for an eccentricity of the hole (34); The pivot (18) comprises: - at least one raceway (42) whose axis coincides with the real axis of the pivot (18), and - at least one shrink-fit seat (40) of the pivot (18) in the hole (34), the axis of which coincides with the theoretical axis of the pivot (18); - comprising a planetary gear carrier (20) having a hole (34) in which the pivot shaft (18) is arranged, the hole (34) and the pivot shaft (18) respectively comprising first and second connecting means adapted to cooperate with each other so as to retain the pivot shaft (18) in a predetermined orientation in the hole (34).

10. An epicyclic gear train (70) according to claim 9, the second connection means comprising an opening (58) having a shape adapted to receive the first connection means.

11. The epicyclic gear train (70) according to claim 10, characterized in that The first connection means may comprise a protruding member (56).

12. The epicyclic gear train (70) according to claim 11, characterized in that An opening (58) is formed in a radial growth E carried by the pivot (18) and is adapted to receive said protruding member (56).

13. The epicyclic gear train (70) according to claim 10, characterized in that The connection means of the hole (34) and the pivot (18) are respectively arranged on a line including a vector oriented from the theoretical axis to the real axis. The angular sector of and including the vector In the angular sector of Oriented from the theoretical axis to the real axis.

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