Drive shaft of an aircraft turbine engine with a connecting ring for removal of the drive shaft

Description

Domaine technique

[0001] The present invention relates to the field of aircraft turbine engines and more particularly relates to a drive line shaft comprising a connecting ring to facilitate the disassembly of the drive line.

[0002] As known, with reference to the [ Fig.1 ], a dual-flow aircraft turbojet engine 100 is shown extending longitudinally along an axis X oriented from upstream to downstream and configured to allow propulsion of the aircraft from the acceleration of an air flow F circulating from upstream to downstream in the turbojet engine 100. Subsequently, the terms “upstream” and “downstream” are defined with respect to the orientation of the longitudinal axis X. The terms “inner” and “outer” are defined in the radial direction with respect to the longitudinal axis X.

[0003] As illustrated in the [ Fig.1 ], the dual-flow aircraft turbojet engine 100 comprises a radially inner primary vein 108 and a radially outer secondary vein 109 in which a first part and a second part of the air flow F circulate respectively, called primary air flow F1 and secondary air flow F2. Furthermore, the turbojet engine 100 comprises from upstream to downstream an air inlet comprising a fan 104 allowing the acceleration of the air flow F, low-pressure 101 and high-pressure 105 compressors allowing the acceleration of the primary air flow F1, a gas combustion chamber 106 with the primary air flow F1 and high-pressure 107 and low-pressure 102 turbines. The high-pressure turbine 107 allows the rotational drive of the high-pressure compressor 105 while the low-pressure turbine 102 allows the rotational drive of the low-pressure compressor 101 and the fan 104.In this example, the turbojet 100 further comprises a reducer 103 connected to the fan 104 and configured to reduce the rotational speed transmitted by the low pressure turbine 102 to the fan 104.

[0004] More precisely, still with reference to the [ Fig.1 ], the turbojet 100 comprises a low pressure drive line A connecting the reducer 103, the low pressure compressor 101 and the low pressure turbine 102 as well as a high pressure drive line B connecting the high pressure compressor 105 and the high pressure turbine 107. The low pressure drive lines A and high pressure B extend coaxially along the longitudinal axis X, the low pressure drive line A extending radially inside the high pressure drive line B.

[0005] Still referring to the [ Fig.1 ], the low pressure drive line A comprises from upstream to downstream a reduction gear shaft 203, a compressor shaft 201 and a turbine shaft 202, in the form of coaxial hollow parts with a longitudinal axis X and on which the reduction gear 103, the low pressure compressor 101 and the low pressure turbine 102 are respectively mounted. The low pressure drive line A also comprises connecting rings 204, 205 for assembling the shafts 203, 201, 202 end to end as well as anti-rotation rings and axial stop segments (not shown) to secure the assembly.

[0006] In practice, maintenance operations must be regularly carried out on the turbojet 100, and in particular on the low-pressure turbine 102, which require disassembling the turbine shaft 202 from the low-pressure drive line A, i.e. disassembling the connecting ring 204 connecting the compressor shaft 201 and the turbine shaft 202. Such a connecting ring 204 is however not directly accessible from the outside, given that it is located at a distance L of more than one meter downstream of the upstream end 206 of the low-pressure drive line A. Such a maintenance operation thus requires complete disassembly and reassembly of the low-pressure drive line A, which is time-consuming.

[0007] To solve this drawback, as illustrated in the [ Fig.2 ], it is known from patent application FR3018313A1 a connecting ring 207 which is inserted by the upstream end 206 of the low pressure drive line A into the reducer shaft 203 and the compressor shaft 201. Such a connecting ring 207 comprises a downstream end 208 configured to be screwed with the turbine shaft 202 and an upstream end 209 configured to come into axial abutment against the end of the compressor shaft 201. Advantageously, during a maintenance operation, such a connecting ring 207 can advantageously be unscrewed and removed from the upstream end 206 of the low pressure drive line A, then reinserted and screwed back in a similar manner. It is thus no longer necessary to disassemble and then reassemble the low pressure drive line A as a whole.

[0008] Also known from patent application US4185937A1 is a fastening device comprising a head portion mounted in abutment in a front shaft, a threaded portion cooperating with a rear shaft, and a deformable ring comprising at rest an anti-rotation ellipsoidal section. To disconnect the shafts, the fastening device comprises a housing with which a tool inserted via the front shaft can cooperate. The passage of the tool deforms the ring which allows rotation and makes it possible to remove the fastening device.

[0009] In fact, as illustrated in the [ Fig.3 ], it is desired to reduce the diameter D203 of the reduction gear shaft 203 in order to reduce the radial size of the reduction gear 103, in particular for aircraft turboshaft engines 100 comprising a variable-pitch fan 104 or an unducted fan 104 which have a large diameter. Such a reduction gear shaft 203 of reduced diameter D203 has the disadvantage of being too narrow to allow the passage of the connecting ring 207 during a maintenance operation. An immediate solution to overcome this disadvantage would be to no longer pass through the inside of the low-pressure drive line A but through the outside thereof. Such a solution is however complex to implement in the loaded environment of the aircraft turbojet engine 100.

[0010] The invention thus aims to be able to disassemble in a simple and practical manner the compressor shaft 201 and the turbine shaft 202 from the low-pressure drive line A during a maintenance operation, in particular in the case of a reduction gear shaft 203 of reduced diameter. The invention also aims generally to be able to disassemble in a simple and practical manner a shaft from an aircraft turbine engine drive line. PRESENTATION DE L'INVENTION

[0011] The invention relates to a main shaft of an aircraft turbine engine drive line according to claim 1 configured to be securely connected to a rear shaft of the drive line, said main shaft extending longitudinally from front to rear along an axis and being in the form of a hollow part defining an open interior cavity, said main shaft comprising a rear portion configured to receive a front portion of the rear shaft by interlocking.

[0012] The invention is remarkable in that the main shaft comprises: at least one front retaining member and at least one rear retaining member positioned in the interior cavity so as to together define a prison and each comprising a central opening, the front portion of the rear shaft comprising a front end configured to extend into the central opening of the rear retaining member, and a connecting ring located in the prison and comprising a rear end configured to be screwed with the front end of the rear shaft and to abut against the rear retaining member, said connecting ring comprising an interior surface on which is formed at least one gripping member accessible from a front portion of the main shaft by a tool extending via the central opening of the front retaining member, in order to allow the driving of the connecting ring in rotation about the longitudinal axis to screw it to the rear shaft,so as to securely connect the main shaft to the rear shaft.

[0013] Thanks to the invention, the main shaft and the rear shaft of a drive line can be disassembled in a simple and practical manner, using only a tool inserted into the interior cavity of the main shaft by the front portion. Thus, even if the access internal diameter is reduced, disassembly is possible since the connecting ring remains captive and does not have to be extracted. In addition, such a captive assembly makes it possible to use a connecting ring whose diameter is sufficient to take up the forces of the rear shaft, in particular, when the latter is in the form of a turbine shaft.

[0014] The connecting ring of the main shaft and the rear shaft extends in fact into the interior cavity of the main shaft, which only requires access to the front to handle it and does not cause any external clutter of the drive line. The connecting ring is furthermore mounted captive in the main shaft which avoids having to extract it in a potentially restricted and complex space, such as a front shaft of reduced diameter, or having to dismantle the possible front shaft. The connecting ring is also easily handled thanks to the gripping member formed on its interior surface, easily accessible from the front by tools. The invention is thus particularly suitable for an aircraft turbine engine representing a loaded and complex environment, where regular maintenance of the parts, such as the shafts, is necessary.

[0015] According to one aspect of the invention, the connecting ring is mounted axially movable in the prison between a connecting position and a waiting position. Advantageously, such a movable connecting ring facilitates the connection and disconnection of the main shaft and the rear shaft. Preferably, in the connecting position, the rear end of the connecting ring extends in abutment against the rear retention member and is configured to cooperate by screwing with the front end of the front portion of the rear shaft, in order to securely connect the main shaft to the rear shaft. Preferably, in the waiting position, the rear end of the connecting ring extends freely at a distance from the rear retention member, in order to facilitate the extraction of the rear shaft.

[0016] In a preferred aspect, the rear end of the connecting ring includes a threaded inner surface configured to threadably engage a threaded outer surface of the front end of the rear shaft. This makes it easy to center the connecting ring and the rear shaft for threading together.

[0017] Preferably, the rear end of the connecting ring comprises an outer diameter greater than the diameter of the central opening of the rear retention member, in order to allow the connecting ring to abut against the rear retention member. Preferably, the connecting ring comprises a front end comprising an outer diameter greater than the diameter of the central opening of the front retention member. Such front and rear retention members advantageously prevent the connecting ring from coming out of the prison.

[0018] According to one aspect of the invention, the gripping member of the connecting ring comprises an inner diameter smaller than the inner diameter of the rear end of said connecting ring. Preferably, the gripping member of the connecting ring comprises an inner diameter smaller than the inner diameter of the front end of said connecting ring. Such a gripping member is advantageously configured to cooperate with a tool of restricted diameter which can thus easily be inserted through the front portion of the main shaft.

[0019] Preferably, the gripping member comprises a plurality of grooves, allowing the tooling to easily screw the connecting ring to the rear shaft, in particular without relative rotation between the connecting ring and the tooling.

[0020] According to one aspect of the invention, the rear retention member is made from the material of the main shaft and thus has optimal rigidity in order to resist the tightening torque of the connecting ring. Preferably, the rear retention member is in the form of an inner radially projecting portion extending from the inner surface of the main shaft.

[0021] According to another preferred aspect, the front retention member is mounted in a reported manner in the interior cavity of the main shaft, in order to allow, during assembly of the main shaft, the insertion of the connecting ring into the prison.

[0022] According to one aspect of the invention, the front retaining member is configured to cooperate with a front end of the connecting ring and with the inner surface of the main shaft so as to keep the connecting ring fixed relative to the main shaft. Such a front retaining member advantageously has two functions, namely to delimit the prison at the front and to block the movement of the connecting ring when the latter is not screwed.

[0023] According to one aspect, the front retaining member is mounted axially movable in the interior cavity of the main shaft between a front position and a rear position. Preferably, in the rear position, the front retaining member keeps the connecting ring fixed in the connecting position relative to the main shaft, in order to secure the connection of the main shaft and the rear shaft. Any involuntary unscrewing of the connecting ring is thus eliminated. Preferably, in the front position, the front retaining member keeps the connecting ring fixed in the waiting position relative to the main shaft, in order to prevent the connecting ring from moving by itself in the prison.

[0024] In a preferred aspect, the front retaining member includes a rotational locking element configured to cooperate with the front end of the connecting ring and with the inner surface of the main shaft to prevent rotation relative to the longitudinal axis of the connecting ring relative to the main shaft.

[0025] According to a preferred aspect, the front retention member comprises an axial locking element configured to cooperate with the front end of the connecting ring and with the inner surface of the main shaft to prevent translation relative to the longitudinal axis of the connecting ring relative to the main shaft.

[0026] According to another preferred aspect, the front end of the connecting ring is configured to be screwed with the rear end of a connecting member configured to extend into the central opening of the front retention member. Such a connecting ring advantageously makes it possible to connect the main shaft on the one hand to the rear shaft and on the other hand to a front shaft.

[0027] According to a preferred aspect, the main shaft is configured to be securely connected to a front shaft of the drive line, the front portion of the main shaft being configured to receive a rear portion of the front shaft by interlocking. The connecting ring advantageously makes it possible to secure and detach the main shaft and the rear shaft in the presence of a front shaft securely connected to the main shaft.

[0028] According to another preferred aspect, the rear portion of the main shaft comprises a power transmission member configured to cooperate with a power transmission member of the front portion of the rear shaft. Preferably, the front portion of the main shaft comprises a power transmission member configured to cooperate with a power transmission member of the rear portion of the front shaft. Preferably, the power transmission member of the front portion and / or the rear portion of the main shaft is in the form of splines formed on the inner surface of the main shaft. Such a power transmission member promotes cooperation between the main shaft and the rear shaft / front shaft.

[0029] The invention also relates to a drive line for an aircraft turbine engine comprising a main shaft as described above and a rear shaft connected integrally, said rear shaft extending longitudinally from front to rear along the axis and being in the form of a hollow part, said rear shaft comprising a front portion fitted into the rear portion of said main shaft, said front portion of the rear shaft comprising a front end extending into the central opening of the rear retention member and cooperating by screwing with the rear end of the connecting ring.

[0030] Preferably, the front end of the rear shaft comprises an outside diameter smaller than the diameter of the central opening of the rear retention member, in order to be easily insertable into the central opening of the rear retention member.

[0031] Preferably, the front end of the rear shaft comprises a threaded outer surface cooperating by screwing with a threaded inner surface of the front end of the connecting ring. Advantageously, the rear end of the connecting ring thus has a larger diameter than the front end of the rear shaft, which promotes the retention of the connecting ring in the prison by limiting the diameter of the central opening of the rear retention member.

[0032] Preferably, the front portion of the rear shaft abuts against the rear retention member, in order to promote the assembly of the main shaft and the rear shaft. Preferably, the front portion of the rear shaft comprises an outside diameter greater than the diameter of the central opening of the rear retention member, to allow the abutment.

[0033] Preferably, the front portion of the rear shaft comprises a power transmission member cooperating with the power transmission member of the rear portion of the main shaft, preferably in the form of splines formed on the inner surface of the front portion of the rear shaft. This promotes assembly of the main shaft and the rear shaft.

[0034] The drive line further comprises a front shaft and a connecting member securely connecting the main shaft and the front shaft, said front shaft extending longitudinally from front to rear along the axis and being in the form of a hollow part, said front shaft comprising a rear portion fitted into a front portion of said main shaft.

[0035] The connecting member is mounted in an internal cavity of the front shaft to cooperate by screwing with the connecting ring. Such a connecting member advantageously does not generate any external bulk and is removable from the front of the front shaft to allow a tool to access the connecting ring without having to dismantle the front shaft from the drive line. In other words, the connecting member comprises an external diameter smaller than the internal diameter of the internal cavity of the front shaft.

[0036] The connecting body includes: a rear end extending into the central opening of the front retention member and cooperating by screwing with a front end of the connecting ring and a gripping member accessible from a front portion of the front shaft by a tool, in order to allow the connecting member to be driven in rotation around the longitudinal axis to screw it to the connecting ring, so as to securely connect the front shaft to the main shaft.

[0037] Preferably, the connecting member is in the form of a non-structural part, namely not transmitting the forces exerted between the connecting ring and the front shaft. Preferably, the connecting ring is in the form of a structural part, namely transmitting the forces exerted between the main shaft and the rear shaft, in particular in traction and in shear. Preferably, the connecting member comprises steel, in particular, is made of steel. Preferably, the connecting ring comprises steel, in particular, is made of steel.

[0038] Preferably, the rear end of the connecting member comprises a threaded outer surface cooperating by screwing with a threaded inner surface of the front end of the connecting ring. Advantageously, the front end of the connecting ring thus has a larger diameter than the rear end of the connecting member, which promotes the retention of the connecting ring in the prison by limiting the diameter of the central opening of the front retention member.

[0039] Preferably, the gripping member is formed on the inner surface of the connecting member to be accessible by a tool of restricted diameter. Preferably, the gripping member comprises a plurality of grooves allowing the tool to screw the gripping member without relative rotation between the connecting member and the tool.

[0040] According to one aspect of the invention, the connecting member comprises a front end extending into abutment against a rear end of the rear portion of the front shaft, in order to secure the front shaft to the connecting ring.

[0041] Preferably, the rear end of the front shaft is in the form of an inner radially projecting portion to provide the stop. Preferably, the front end of the connecting member comprises an outer radially projecting portion to provide the stop.

[0042] According to a preferred aspect, the drive line further comprises a locking member configured to keep the connecting member fixed relative to the front shaft, in order to secure the assembly. Preferably, the locking member is configured to cooperate with the front end of the connecting member and with the inner surface of the front shaft.

[0043] The invention also relates to an aircraft turbine engine comprising a drive line as described above. Preferably, the turbine engine extends longitudinally along the axis and is configured to enable propulsion of the aircraft from the acceleration of an air flow circulating from upstream to downstream in the turbine engine, the longitudinal axis being oriented from upstream to downstream. A main shaft oriented from upstream to downstream advantageously allows access to the connecting ring from upstream of the turbine engine, in particular by removing the fan cone from the turbine engine.

[0044] In one aspect, the main shaft is in the form of a compressor shaft configured to be connected to a compressor of the turbine engine, preferably to a low-pressure compressor of the turbine engine. For such a compressor shaft remote from the upstream end of the turbine engine and having reduced access, the connecting ring accessible from the upstream and mounted captively is particularly advantageous.

[0045] In one aspect, the rear shaft is in the form of a turbine shaft configured to be connected to a turbine of the turboshaft engine extending downstream of the compressor, the compressor shaft being configured to be integrally connected to the turbine shaft such that the rotation of the turbine generated by the air flow drives the compressor in rotation. Preferably, the turbine shaft is configured to be connected to a low-pressure turbine of the turboshaft engine.

[0046] According to one aspect, the front shaft is in the form of a reduction gear shaft configured to be connected to a reduction gear of the turbine engine, the turbine engine comprising an air inlet comprising a fan extending upstream of the compressor, said reduction gear being connected to the fan and configured to reduce the rotational speed transmitted by the turbine to the fan, the compressor shaft being configured to be securely connected to the reduction gear shaft so that the rotation of the compressor drives the fan in rotation.

[0047] Preferably, the reduction gear shaft has a reduced diameter, namely an internal diameter at least locally less than 60 mm. Such a reduction gear shaft is suitable for a turbine engine comprising a variable pitch fan and / or an unducted fan. Preferably, the aircraft turbine engine is in the form of a turbojet, preferably a double-flow turbojet comprising a radially inner primary vein and a radially outer secondary vein.

[0048] Preferably, the front shaft comprises steel, in particular, is made of steel. Preferably, the front shaft is convoluted to promote alignment of the drive line. According to another preferred aspect, the front shaft comprises at least one circumferential flexibility element, preferably in the form of a bellows.

[0049] In one aspect, the drive line is in the form of an aircraft turbine engine low pressure drive line configured to extend coaxially and radially inward of a high pressure drive line of the turbine engine. Preferably, the high pressure drive line is configured to connect a high pressure compressor and a high pressure turbine of the turbine engine. Such a low pressure drive line has restricted access and volume due to the presence of the high pressure drive line.

[0050] The invention relates in particular to a drive line as described above, in the form of a low-pressure drive line for an aircraft turbine engine configured to extend coaxially and radially inside a high-pressure drive line of the turbine engine, said turbine engine extending longitudinally along the axis and being configured to enable propulsion of the aircraft from the acceleration of an air flow circulating from upstream to downstream in the turbine engine, the longitudinal axis being oriented from upstream to downstream, the main shaft in the form of a compressor shaft configured to be connected to a low-pressure compressor of the aircraft turbine engine.

[0051] The invention also relates to a method for dismantling an aircraft turbine engine drive line as described above, comprising: a step of unscrewing the rear end of the connecting ring by means of a tool inserted through the front portion of the main shaft, extending via the central opening of the front retaining member and cooperating with the gripping member of the connecting ring in order to drive the connecting ring in rotation around the longitudinal axis, so as to separate the connecting ring and the rear shaft, the connecting ring remaining trapped in the prison, and a step of extracting the front portion of the rear shaft from the rear portion of the main shaft, so as to separate the main shaft and the rear shaft.

[0052] Such a disassembly process makes it possible to easily separate the rear shaft from the main shaft by unscrewing the connecting ring with a tool inserted through the front portion of the main shaft. The rear shaft can thus be disassembled with reduced access and without disassembling the shaft(s) located in front of it. Such a process saves significant time.

[0053] Preferably, the connecting ring is initially in the connecting position, in which the rear end of the connecting ring extends into abutment against the rear retention member and cooperates by screwing with the front end of the front portion of the rear shaft, in order to securely connect the main shaft to the rear shaft.

[0054] Preferably, at the end of the unscrewing step, the connecting ring is in the waiting position, in which the rear end of the connecting ring extends freely at a distance from the rear retention member.

[0055] Preferably, the front retaining member is initially in the rear position, in which it keeps the connecting ring fixed in the connecting position relative to the main shaft, and the disassembly method comprises, before the unscrewing step, a step of releasing the connecting ring by moving the front retaining member.

[0056] Preferably, the disassembly method comprises, after the unscrewing step, a step of securing the connecting ring in the waiting position by means of the front retention member in the front position, in which it keeps the connecting ring fixed relative to the main shaft.

[0057] Preferably, the method comprises a step of extracting the connecting member. Such a disassembly method makes it possible to separate the rear shaft while keeping the front shaft and the main shaft fitted together, via the extraction of the connecting member.

[0058] Preferably, the extracting step is implemented by moving the connecting member into the interior cavity of the front shaft to the front portion of the front shaft.

[0059] Preferably, the method comprises, before the extraction step, a step of unscrewing the rear end of the connecting member by means of a tool inserted by the front portion of the front shaft and cooperating with the gripping member of the connecting member in order to drive the connecting member in rotation around the longitudinal axis, so as to separate the connecting member and the connecting ring.

[0060] Preferably, the method further comprises, before the unscrewing step, a step of releasing the connecting member by extracting the locking member, preferably by moving the locking member into the interior cavity of the front shaft to the front portion of the front shaft.

[0061] The invention also relates to a method of mounting the aircraft turbine engine drive line in which the connecting ring extends captive in the prison of the main shaft, said method comprising: a step of inserting the front portion of the rear shaft into the rear portion of the main shaft by interlocking, so as to secure the main shaft and the rear shaft and a step of screwing the rear end of the connecting ring with the front end of the rear shaft, by means of a tool inserted by the front portion of the main shaft, extending via the central opening of the front retention member and cooperating with the gripping member of the connecting ring in order to drive the connecting ring in rotation about the longitudinal axis, so as to secure the connecting ring and the rear shaft.

[0062] Preferably, the connecting ring is initially in a standby position in which the rear end of the connecting ring extends free away from the rear retention member.

[0063] Preferably, at the end of the screwing step, the connecting ring is in the connecting position, in which the rear end of the connecting ring extends into abutment against the rear retention member and cooperates by screwing with the front end of the front portion of the rear shaft, in order to securely connect the main shaft to the rear shaft.

[0064] Preferably, the front retaining member is initially in the front position, in which it keeps the connecting ring fixed in the waiting position relative to the main shaft, and the assembly method comprises, before the screwing step, a step of releasing the connecting ring relative to the front retaining member.

[0065] Preferably, the assembly method comprises, after the screwing step, a step of securing the connecting ring in the connecting position by means of the front retaining member moved to the rear position, in which it keeps the connecting ring fixed relative to the main shaft.

[0066] Preferably, said method comprises a step of inserting the connecting member. Preferably, the insertion step is carried out by moving the connecting member into the interior cavity of the front shaft from the front portion of the front shaft.

[0067] Preferably, the assembly method comprises, after the insertion step, a step of screwing the rear end of the connecting member with the front end of the connecting ring by means of a tool inserted by the front portion of the front shaft and cooperating with the gripping member of the connecting member in order to drive the connecting member in rotation around the longitudinal axis, so as to secure the connecting member and the connecting ring.

[0068] Preferably, the assembly method comprises, after the screwing step, a step of securing the connecting member by means of the locking member, preferably inserted into the interior cavity of the front shaft from the front portion of the front shaft.

[0069] The invention further relates to the method of mounting a main shaft as described previously in which the connecting ring and then the front retaining member are inserted from the front portion of the main shaft into the interior cavity, so as to define a prison in which the connecting ring extends captively. PRESENTATION DES FIGURES

[0070] The invention will be better understood on reading the description which follows, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects: There [ Fig.1 ] is a schematic representation in longitudinal half-section of a dual-flow aircraft turboshaft engine with a low-pressure drive line according to the prior art; The [ Fig.2 ] is a functional schematic representation in longitudinal section of the low pressure drive line of the [ Fig.1 ] with a connecting ring of the compressor shaft and the turbine shaft insertable from upstream according to the prior art; The [ Fig.3 ] is a functional schematic representation in longitudinal section of the low pressure drive line of the [ Fig.2 ] with a reduced diameter reducer shaft according to the prior art; The [ Fig.4 ] is a schematic representation in longitudinal half-section of a dual-flow aircraft turbine engine with a low-pressure drive line according to one embodiment of the invention; The [ Fig.5 ] and The [ Fig.6 ] are two schematic representations in longitudinal section of the low pressure drive line of the [ Fig.4 ] respectively mounted and dismounted according to an embodiment of the invention; The [ Fig.7 ] is a schematic representation of the connecting ring of the low pressure drive line of the [ Fig.5 ] ; There [ Fig.8 ] is a schematic representation of the connecting member of the low pressure drive line of the [ Fig.5 ] ; There [ Fig.9 ] is a schematic representation of the steps in the process of dismantling the low pressure drive line of the [ Fig.5 ] ; There [ Fig.10 ] is a schematic representation of the steps in the process of assembling the low pressure drive line of the [ Fig.5 ] ; There [ Fig.11 ] is a schematic representation of the step of releasing / locking the connecting member and the step of unscrewing / screwing the connecting member according to the disassembly / assembly method of the [ Fig.9 ] / [ Fig.10 ] ; There [ Fig.12 ] is a schematic representation of the step of extracting / inserting the connecting member according to the disassembly / assembly method of the [ Fig.9 ] / [ Fig.10 ] ; There [ Fig.13 ] is a schematic representation of the step of releasing / locking the connecting ring in the connecting position and of the step of unscrewing / screwing the connecting ring according to the method of disassembling / assembling the [ Fig.9 ] / [ Fig.10 ] ; and The [ Fig.14 ] is a schematic representation of the step of securing / unlocking the connecting ring in the waiting position and the step of extracting / inserting the turbine shaft according to the disassembly / assembly method of the [ Fig.9 ] / [ Fig.10 ].

[0071] It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate. DESCRIPTION DETAILLEE DE L'INVENTION

[0072] With reference to the [ Fig.4 ], a dual-flow aircraft turbojet engine 100 is shown extending longitudinally along an axis X oriented from upstream to downstream and configured to allow propulsion of the aircraft from the acceleration of an air flow F circulating from upstream to downstream in the turbojet engine 100. Subsequently, the terms “upstream” and “downstream” are defined with respect to the orientation of the longitudinal axis X. The terms “inner” and “outer” are defined in the radial direction with respect to the longitudinal axis X.

[0073] Still referring to the [ Fig.4 ] and as described in the preamble, the dual-flow aircraft turbojet 100 comprises a radially inner primary vein 108 and a radially outer secondary vein 109 in which a first part and a second part of the air flow F circulate respectively, called primary air flow F1 and secondary air flow F2. Furthermore, the turbojet 100 comprises from upstream to downstream an air inlet comprising a fan 104 allowing the acceleration of the air flow F, low pressure 101 and high pressure 105 compressors allowing the acceleration of the primary air flow F1, a gas combustion chamber 106 with the primary air flow F1 and high pressure 107 and low pressure 102 turbines. The high pressure turbine 107 allows the rotational drive of the high pressure compressor 105 while the low pressure turbine 102 allows the rotational drive of the low pressure compressor 101 and the fan 104.In this example, the turbojet engine 100 further comprises a reducer 103 connected to the fan 104 and configured to reduce the rotational speed transmitted by the low-pressure turbine 102 to the fan 104. It goes without saying that the invention also applies to a turbojet engine without a reducer 103.

[0074] Still referring to the [ Fig.4 ] and as described in the preamble, the turbojet 100 comprises a low-pressure drive line A connecting the reducer 103, the low-pressure compressor 101 and the low-pressure turbine 102 as well as a high-pressure drive line B connecting the high-pressure compressor 105 and the high-pressure turbine 107. In this example, the low-pressure and high-pressure drive lines A extend coaxially along the longitudinal axis X. The low-pressure drive line A extends radially inside the high-pressure drive line B. It goes without saying that the number of drive lines could be different. The same applies to their relative positioning.

[0075] As illustrated in the [ Fig.4 ] and described in the preamble, the low pressure drive line A comprises from upstream to downstream a reducer shaft 3, a compressor shaft 1 and a turbine shaft 2, in the form of coaxial hollow parts with longitudinal axis X and on which are mounted respectively the reducer 103, the low pressure compressor 101 and the low pressure turbine 102.

[0076] According to the invention and still with reference to the [ Fig.4 ], the low pressure drive line A further comprises a connecting ring 4 ([ Fig.7 ]) securely connecting the compressor shaft 1 and the turbine shaft 2, and preferably, a connecting member 5 ([ Fig.8 ]) solidly connecting the compressor shaft 1 and the reducer shaft 3, as will be presented later.

[0077] The invention will be presented for the connection of a compressor shaft 1 and a turbine shaft 2 and the connection of a compressor shaft 1 and a reducer shaft 3 but it goes without saying that the shafts could be of different natures.

[0078] In the example of the [ Fig.5 ] and the [ Fig.6 ], the compressor shaft 1 is in the form of a hollow part with a longitudinal axis X comprising an interior surface 17 defining an interior cavity 12, in which are mounted a front retention member 6, a connecting ring 4 and a rear retention member 11 between a front portion 14 and a rear portion 10.

[0079] As illustrated in the [ Fig.5 ] and the [ Fig.6 ], the front portion 14 and the rear portion 10 are configured to receive by nesting respectively a rear portion 30 of the reduction gear shaft 3 and a front portion 20 of the turbine shaft 2. The front portion 14 and the rear portion 10 of the compressor shaft 1 each comprise a stop element for axially limiting the nesting. In this example, with reference to the [ Fig.6 ], the stop element of the front portion 14 is in the form of a narrowing 18 of the diameter of the inner surface 17. The stop element of the rear portion 10 is in the form of the rear retention member 11.

[0080] The front portion 14 and the rear portion 10 of the compressor shaft 1 each comprise a power transmission member 15, 16 configured to cooperate with power transmission members 34, 23 of the reduction gear shaft 3 and the turbine shaft 2 in order to allow the transmission of a torque from the turbine shaft 2 to the compressor shaft 1 and then to the reduction gear shaft 2. Preferably, the power transmission members 16, 15, 34, 23 are in the form of grooves formed on the inner surface 17, 35, 24 of the compressor shaft 1, the reduction gear shaft 3 and the turbine shaft 2. The shafts 1, 2, 3 are thus coupled in rotation.

[0081] As will now be presented, the connecting ring 4 makes it possible to axially secure the compressor shaft 1 and the turbine shaft 2 while the connecting member 5 makes it possible to axially secure the compressor shaft 1 and the reduction gear shaft 3.

[0082] Still in the example of the [ Fig.5 ] and the [ Fig.6 ], the front retention member 6 and the rear retention member 11 together define a prison 13 in the interior cavity 12 in which the connecting ring 4 is mounted captive in order to limit its axial displacement. The connecting ring 4 is movable between a connection position P4-1 with the turbine shaft 2 and a waiting position P4-2 which will be presented later. The use of a prison 13 advantageously makes it possible to maintain a sufficiently large diameter of the connecting ring 4 to allow an axial connection while having a reducer shaft 3 having a reduced internal diameter.

[0083] In the example of the [ Fig.5 ] and the [ Fig.6 ], the rear retention member 11 is made from the material of the compressor shaft 1 and is in the form of an inner radially projecting portion of the inner surface 17. The rear retention member 11 is configured to form a double stop element, upstream for the connecting ring 4 and downstream for the turbine shaft 2. The rear retention member 11 comprises a central opening 110 to allow a front end 21 of the front portion 20 of the turbine shaft 2 to pass through in order to be able to secure the connecting ring 4 and the turbine shaft 2 on either side of the rear retention member 11. In practice, the central opening 110 of the rear retention member 11 has a diameter smaller than the outer diameter of the connecting ring 4 to retain it in the prison 13.Conversely, the central opening 110 of the rear retention member 11 has a diameter greater than the outside diameter of the front end 21 of the turbine shaft 2 to allow it to pass.

[0084] Thus, the connecting ring 4 extends strictly between the front retention member 6 and the rear retention member 11. In addition, the rear end of the connecting ring 4 has a diameter greater than that of the rear retention member 11. Similarly, the front end of the connecting ring 4 has a diameter greater than that of the front retention member 6.

[0085] In the example of the [ Fig.5 ] and the [ Fig.6 ], the front retention member 6 is mounted in a fixed manner in the internal cavity 12 of the compressor shaft 1 so as to be able to access the connecting ring 4.

[0086] According to a preferred aspect, the front retention member 6 is movably mounted in the interior cavity 12 between a rear position P6-1 illustrated in the [ Fig.5 ], in which it keeps the connecting ring 4 fixed in the connecting position P4-1 relative to the compressor shaft 1, and a forward position P6-2 illustrated in the [ Fig.6 ], in which it keeps the connecting ring 4 fixed in the waiting position P4-2 relative to the compressor shaft 1.

[0087] The front retaining member 6 is configured to cooperate with the connecting ring 4 and with the inner surface 17 of the compressor shaft 1, in order to keep the connecting ring 4 fixed relative to the compressor shaft 1. More precisely, the front retaining member 6 in the rear position P6-1 blocks the connecting ring 4 in the connecting position P4-1 in order to prevent any involuntary unscrewing. The front retaining member 6 in the front position P6-2 blocks the connecting ring 4 in the waiting position P4-2 to prevent any movement in the prison 13. The front retaining member 6 preferably comprises a rotational locking element, such as a stop brake, and an axial locking element, such as a circlip. The front retaining member 6 further comprises a central opening 60 in order to allow the passage of tools for handling the connecting ring 4.The central opening 60 also allows a rear end 50 of the connecting member 5 to pass through in order to allow its cooperation with the connecting ring 4. In practice, the diameter of the central opening 60 is less than the outside diameter of the connecting ring 4 to retain it.

[0088] With reference to the [ Fig.5 ] and to the [ Fig.6 ], the connecting ring 4 is located in the prison 13 of the compressor shaft 1 and is configured to secure it on the one hand to the turbine shaft 2 and on the other hand, in cooperation with the connecting member 5, with the reducer shaft 3. More precisely, in the connecting position P4-1 ([ Fig.5 ]), the connecting ring 4 cooperates with the turbine shaft 2, in abutment against the rear retention member 11 and secured by the front retention member 6. In the waiting position P4-2 ([ Fig.6 ]), the connecting ring 4 is held fixed in the prison 13 by the front retention member 6.

[0089] Preferably, the connecting ring 4 is preferably in the form of a structural part, allowing the compressor shaft 1 to take up the forces of the turbine shaft 2.

[0090] With reference to the [ Fig.7 ], the connecting ring 4 is in the form of a hollow part comprising an inner surface 42, a front end 44 configured to cooperate by screwing with the connecting member 5 and a rear end 40 configured to cooperate with the turbine shaft 2. The front end 44 is further configured to cooperate with the front retention member 6 while the rear end 40 is configured to abut against the rear retention member 11. More precisely, the front end 44 and the rear end 40 each comprise a threaded inner surface 45, 41 which are respectively configured to cooperate with threaded outer surfaces 22, 51 of the turbine shaft 2 and of the connecting member 5.

[0091] A gripping member 43 is formed on the inner surface 42 between the front end 44 and the rear end 40, separated from the tapped inner surfaces 45, 41 by a front separating member 47 and a rear separating member 46. Still with reference to the [ Fig.7 ], the gripping member 43 is configured to cooperate with a tool in order to drive the connecting ring 4 in rotation and to enable its cooperation with the turbine shaft 2. In the example of the [ Fig.7 ], the gripping member 43 is in the form of grooves formed on the inner surface 42 allowing good cooperation with the tooling, and in particular to allow the tooling to transmit a rotational torque to the connecting ring 4 to allow it to be screwed. In this example, the gripping member 43 comprises an inner diameter smaller than that of the front end 44 and the rear end 40, allowing cooperation with a tooling of reduced diameter, easily insertable into the low pressure drive line A.

[0092] In the example of the [ Fig.7 ], the front separating member 47 and the rear separating member 46 are in the form of a transverse annular notch allowing respectively to axially limit the screwing to the connecting member 5 and to the turbine shaft 2.

[0093] A tapping of the front end 44 and the rear end 40 is preferred to a thread in order to avoid significant radial play of the connecting ring 4 in the prison 13.

[0094] In the P4-1 link position, as shown in the [ Fig.5 ], the rear end 40 of the connecting ring 4 is in abutment against the rear retention member 11 and cooperates by screwing with the front end 21 of the front portion 20 of the turbine shaft 2, in order to axially connect the compressor shaft 1 to the turbine shaft 2. In the standby position P4-2, as illustrated in the [ Fig.6 ], the rear end 40 of the connecting ring 4 extends freely at a distance from the rear retaining member 11, in order to be able to separate the turbine shaft 2.

[0095] To summarize, according to the invention, there is provided a connecting ring 4 mounted captive in the internal cavity 12 of a compressor shaft 1 and whose rear end 40 cooperates by screwing with a front end 21 of a turbine shaft 2, in order to secure them. A rear retaining member 11 retains the connecting ring 4 captive downstream while allowing the front end 21 of the turbine shaft 2 to pass to allow the securing. A front retaining member 6 retains the connecting ring 4 captive upstream and prevents it from being unscrewed. The front retaining member 6 also keeps the connecting ring 4 fixed when the turbine shaft 2 is detached.

[0096] As described above, a connecting member 5 is also provided connecting the compressor shaft 1 and the reducer shaft 3. A locking member 7 is configured to keep the connecting member 5 fixed relative to the reducer shaft 3, so as to secure the cooperation of the connecting member 5 and the connecting ring 4.

[0097] With reference to the [ Fig.5 ] and to the [ Fig.6 ], the connecting member 5 and the locking member 7 are mounted in the inner cavity 32 of the reducer shaft 3, inserted by a front portion 33 of the reducer shaft 3. The connecting member 5 cooperates with the connecting ring 4 to secure the reducer shaft 3 to the compressor shaft 1. The locking member 7 cooperates with the inner surface 35 of the reducer shaft 3 and with the connecting member 5 to secure the connection. Preferably, the locking member 7 comprises, in a manner similar to the front retention member 6, a rotational locking element, such as a stopping brake, and an axial locking element, such as a circlip, for optimal securing.

[0098] With reference to the [ Fig.8 ], the connecting member 5 is in the form of a hollow part comprising an inner surface 55, a front end 52 configured to cooperate with the reduction gear shaft 3 and a rear end 50 configured to cooperate with the connecting ring 4. More precisely, the rear end 50 is configured to extend into the central opening 60 of the front retention member 6 and comprises a threaded outer surface 51 configured to cooperate by screwing with the tapped inner surface 45 of the connecting ring 4.

[0099] Still referring to the [ Fig.8 ], the front end 52 comprises an outer radially projecting portion 53 and a gripping member 54 formed on the inner surface 55 of the connecting member 5. The outer radially projecting portion 53 is configured to extend into abutment against a rear end 31 of the rear portion 30 of the reducer shaft 3, in order to secure the reducer shaft 3 to the connecting ring 4. For an optimal stop, the rear end 31 of the reducer shaft 3 is in the form of an inner projecting rim. The gripping member 5 is configured to cooperate with a tool in order to rotate the connecting member 5 and to allow its cooperation with the connecting ring 4. In the example of the [ Fig.8 ], the gripping member 54 is in the form of grooves formed on the inner surface 55 allowing good cooperation with the tooling to transmit a screwing torque.

[0100] Preferably, the connecting member 5 is in the form of a flexible part, i.e. non-structural, which transmits very little force. The diameter of the connecting member 5 is chosen as a function of that of the reduction gear shaft 3 and is smaller than the internal diameter of said reduction gear shaft 3 in order to allow its insertion and extraction. The non-structural nature of the connecting member 5 advantageously makes it possible to limit its diameter.

[0101] In other words, it is provided according to a preferred aspect of the invention that the connecting ring 4 cooperates by screwing on the one hand with the turbine shaft 2, at its rear end 40, and on the other hand with a connecting member 5, at its front end 44. The connecting ring 4 thus makes it possible to secure the compressor shaft 1 and the turbine shaft 2 and cooperates with the connecting member 5 to secure the compressor shaft 1 and the reduction gear shaft 3.

[0102] By means of the invention, the compressor shaft 1 and the turbine shaft 2 of a low-pressure drive line A are connected reliably and securely. In addition, they can be separated in a simple and practical manner thanks to the connecting ring 4 mounted captive in the compressor shaft 1. The gripping member 43 of the connecting ring 4 allows a tool to manipulate it remotely from upstream to screw it and unscrew it from the turbine shaft 2. In particular, in the presence of a reduction gear shaft 3, the connecting ring 4 makes it possible to separate the turbine shaft 2 without dismantling the upstream shafts, i.e. the compressor shaft 1 and the reduction gear shaft 3. A captive connecting ring 4 allows the latter to have a large diameter, in particular greater than that of the internal diameter of the reduction gear shaft 3, to take up the forces of the turbine shaft 2.It is only necessary to extract the connecting member 5 from upstream of the low pressure drive line A, in practice via the cone of the fan 104. This saves time, particularly in the case of maintenance of the low pressure turbine 102.

[0103] The invention is particularly suitable for a reducer shaft 3 of reduced diameter, namely whose internal diameter is at least locally less than 60 mm. Such a reducer shaft 3 is provided in particular in the presence of a variable pitch fan 104 or even an unducted fan 104, which have a large diameter requiring that the diameter of the reducer shaft 3 be reduced. Preferably, the reducer shaft 3 comprises steel. Preferably, the front shaft is convoluted to promote alignment of the drive line A. Alternatively, the reducer shaft 3 comprises at least one circumferential flexibility element, preferably in the form of a bellows.

[0104] Furthermore, it goes without saying that the invention is not limited to the connection of a compressor shaft 1 with a turbine shaft 2 and a reduction gear shaft 3 of a low-pressure drive line A of a dual-flow aircraft turbojet 100, as presented previously. The invention in fact encompasses the connection of any main shaft 1 with a rear shaft 2 of any drive line A of any aircraft turboshaft engine 100. The invention notably encompasses the connection of any main shaft 1 on the one hand with a rear shaft 2 and on the other hand with a front shaft 3 of any drive line A of any aircraft turboshaft engine 100. Note that the terms "front" and "rear" referring here to the upstream and downstream of the aircraft turboshaft engine 100 could be reversed.The preceding description and the one which follows are here adaptable to another embodiment by replacing the terms: "compressor shaft 1", "turbine shaft 2", "reducer shaft 3", "upstream", "downstream", low pressure drive line A" and "bypass aircraft turbojet 100" respectively by: "main shaft 1", "rear shaft 2", "front shaft 3", "front", rear", "drive line A" and "aircraft turboshaft 100".

[0105] A method for dismantling the low-pressure drive line A previously presented is described below, making it possible to separate the turbine shaft 2 from the compressor shaft 1, while keeping the reduction gear shaft 3 and the compressor shaft 1 fitted together. Such a dismantling method is for example implemented during a maintenance step of the low-pressure turbine 102.

[0106] With reference to the [ Fig.9 ], the method for dismantling the low-pressure drive line A aims, firstly, to remove the connecting member 5, via a release step E1, an unscrewing step E2 and an extraction step E3, then, secondly, to detach the connecting ring 4, via a release step E4, an unscrewing step E5 and a securing step E6, in order to be able to remove the turbine shaft 2 during an extraction step E7.

[0107] As illustrated in the [ Fig.11 ], the reduction gear shaft 3, the compressor shaft 1 and the turbine shaft 2 are initially connected in a fixed manner, so that the rotational drive of the turbine shaft 2 drives the compressor shaft 1 and the reduction gear shaft 3 in rotation. In other words, the connecting ring 4 is initially in the connection position P4-1 and the front retaining member 6 in the rear position P6-1, which ensures the axial connection of the compressor shaft 1 and the turbine shaft 2. In addition, the connecting member 5 cooperates with the connecting ring 4 and the locking member 7 secures the cooperation, which ensures the connection of the compressor shaft 1 and the reduction gear shaft 3.

[0108] Before implementing the disassembly method, the fan cone 104 is disassembled so that the front portion 33 of the reduction gear shaft 3 is accessible.

[0109] Still referring to the [ Fig.11 ], during the release step E1, a tool is inserted through the front portion 33 of the reducer shaft 3, in order to detach the locking member 7 and remove it from the front. The connecting member 5 at the end of the release step E1 is thus no longer held fixed by the locking member 7.

[0110] Still referring to the [ Fig.11 ], during the unscrewing step E2, a tool is again inserted through the front portion 33 of the reducer shaft 3, in order to cooperate with the gripping member 54 of the connecting member 5. The rotation of the tool makes it possible to rotate the connecting member 5 and thus unscrew its rear end 50. At the end of the unscrewing step E2, the rear end 50 of the connecting member 5 no longer cooperates with the front end 44 of the connecting ring 4. Following the unscrewing, the reducer shaft 3 is no longer axially locked relative to the compressor shaft 2.

[0111] With reference to the [ Fig.12 ], the extraction step E3 of the connecting member 5 is implemented by moving it in the interior cavity 32 to the front portion 33 of the reduction gear shaft 3. At the end of the extraction step E3, the connecting ring 4, and in particular the gripping member 43, is accessible from upstream of the low-pressure drive line A. In this exemplary implementation, the reduction gear shaft 3 is still fitted into the compressor shaft 1, and remains so for the following steps of the disassembly method.

[0112] With reference to the [ Fig.13 ], during the release step E4, a tool is inserted through the front portion 33 of the reducer shaft 3, in order to move the front retention member 6 forwards which prevents any rotation of the connecting ring 4. Thus, at the end of the release step E4, the front retention member 6 has been moved from its rear position P6-1 and no longer holds the connecting ring 4 in the connecting position P4-1 which can then be unscrewed.

[0113] Still referring to the [ Fig.13 ], during the unscrewing step E5, a tool is again inserted through the front portion 33 of the reducer shaft 3, in order to cooperate with the gripping member 43 of the connecting ring 4, in particular, through the central opening 60 of the front retaining member 6. The rotation of the tool makes it possible to rotate the connecting ring 4 and thus to unscrew its rear end 40. At the end of the unscrewing step E5, the rear end 40 of the connecting ring 4 no longer cooperates with the front end 21 of the turbine shaft 2. There is thus no longer an axial connection between the compressor shaft 1 and the turbine shaft 1. During unscrewing, the connecting ring 4 moves forward in its prison 13. It is not necessary to remove it entirely as in the prior art. This allows the retention of a connecting ring 4 with a large cross-section to ensure optimal axial locking.

[0114] With reference to the [ Fig.14 ], a securing step E6 of the connecting ring 4 is carried out by making the connecting ring 4 and the front retention member 6 cooperate. At the end of the securing step E6, the connecting ring 4 is in the waiting position P4-2 and the front retention member 6 is in the front position P6-2. Such a securing step E6 makes it possible to avoid any involuntary movement of the connecting ring 4 in the prison 13.

[0115] There [ Fig.14 ] also illustrates the extraction of the front portion 20 of the turbine shaft 2 from the rear portion 10 of the connecting ring 4. At the end of the disassembly process, the compressor shaft 1 and the reducer shaft 3 are still fitted together.

[0116] It should be noted that the securing step E6 of the connecting ring 4 and the extraction step E7 of the turbine shaft 2 can be implemented in any order. It should also be noted that the same tool or different tools can be used for implementing the different steps of the disassembly method. In particular, a tool can be kept inserted in the internal cavity 32 of the reducer shaft 3 between two steps to limit handling.

[0117] Such a disassembly method advantageously makes it possible to simply and practically separate the turbine shaft 2, without disassembling the shafts located upstream, i.e. the compressor shaft 1 and the reduction gear shaft 3, which allows a significant saving of time. Furthermore, the disassembly method can be implemented for a reduction gear shaft 3 of any diameter, and in particular of reduced diameter, thanks to the captively mounted connecting ring 4.

[0118] The invention also relates to a method for mounting the turbine shaft 2 on the low pressure drive line A, implemented in particular after the dismantling method previously presented in order to reassemble the low pressure drive line once maintenance has been completed.

[0119] As illustrated in the [ Fig.10 ], the assembly method comprises the same steps as the disassembly method, implemented in reverse order and in reverse order. In other words, the assembly method aims to fit the turbine shaft 2 into the compressor shaft 1 during an insertion step E7' then, firstly, to secure the connecting ring 4, via a release step E6', a screwing step E5' and a securing step E4', and secondly, to secure the connecting member 5, via an insertion step E3', a screwing step E2' and a securing step E1'.

[0120] More specifically, with reference to the [ Fig.14 ], the compressor shaft 1 and the reducer shaft 3 are initially fitted together but not axially secured by the connecting member 5. The connecting ring 4 and the front retention member 6 are respectively in the waiting position P4-2 and in the front position P6-2.

[0121] Still referring to the [ Fig.14 ], the assembly method begins by inserting the front portion 20 of the turbine shaft 2 into the rear portion 10 of the compressor shaft 1 by interlocking (insertion step E7') until the turbine shaft 2 comes into abutment with the rear retaining member 11. During the insertion step, the splines of the shafts 1, 2 cooperate together.

[0122] In this exemplary implementation, the front retaining member 6 is detached from the connecting ring 4, by means of a tool inserted through the front portion 33 of the reducer shaft 3 (release step E6'). At the end of the release step E6', the front retaining member 6 has been moved from its front position P6-2 and no longer holds the connecting ring 4 in the waiting position P4-2. The insertion step E7' and the release step E6' can be implemented in any order.

[0123] With reference to the [ Fig.13 ], during the screwing step E5', a tool is inserted through the front portion 33 of the reducer shaft 3, in order to cooperate with the gripping member 43 of the connecting ring 4. The tool is introduced into the central opening 60 of the front retaining member 6. The rotation of the tool makes it possible to rotate the connecting ring 4 and thus screw its rear end 40 to the front end 21 of the turbine shaft 2. The tightening torque is high so that the connecting ring 4 takes up the forces of the turbine shaft 2. Advantageously, the connecting ring 4 can move axially in its prison 13 to reach the front end 21 of the turbine shaft 2.

[0124] At the end of the screwing step E5', the connecting ring 4 is in the connecting position P4-1. The rear retention member 11 of the compressor shaft 1 is sandwiched between the connecting ring 4 and the turbine shaft 2, which axially secures the compressor shaft 1 and the turbine shaft 2.

[0125] The securing step E4' is then implemented by securing the front retaining member 6 to the connecting ring 4 in the connecting position P4-1. Thus, any involuntary loosening due to vibrations is eliminated. At the end of the securing step E4', the front retaining member 6 is in the rear position P6-1.

[0126] With reference to the [ Fig.11 ] and to the [ Fig.12], the connecting member 5 is then inserted through the front portion 33 of the reducer shaft 3 (insertion step E3') then its rear end 50 is screwed to the front end 44 of the connecting ring 4 (screwing step E2') so as to achieve axial locking of the reducer shaft 3 relative to the compressor shaft 1, the external radial projection 53 of the connecting member 5 exerting an axial pressing force directed towards the rear.

[0127] The locking member 7 is then inserted through the front portion 33 of the reduction gear shaft 3 and secures the screwing (securing step E1'). At the end of the securing step E1', the compressor shaft 1 and the reduction gear shaft 3 are connected in a fixed manner and the low-pressure drive line A is mounted.

[0128] As with the disassembly process, the same tool or different tools may be used to implement the different steps of the assembly process. In particular, a tool may be kept inserted in the internal cavity 32 of the reducer shaft 3 between two steps to limit handling.

[0129] Such an assembly method makes it possible to simply and practically reassemble the turbine shaft 2 to the low-pressure drive line A, particularly after maintenance.

[0130] The invention further relates to a method for mounting the compressor shaft 1, prior to its integration into the low-pressure drive line A, which consists of successively inserting the connecting ring 4 and the front retaining member 6 into the internal cavity 12, in order to define a prison 13 in which the connecting ring 4 is mounted captive.

Claims

1. Drive line (A) of an aircraft turbine engine (100) comprising a main shaft (1) and a rear shaft (2) integrally connected, the drive line (A) further comprising a front shaft (3) and a connecting member (5) integrally connecting the main shaft (1) and the front shaft (3), each of said main shaft (1), said rear shaft (2) and said front shaft (3) extending longitudinally from front to rear along an axis (X) and having the form of a hollow part, said main shaft (1) defining an open inner cavity (12), said main shaft (1) comprising a rear portion (10) and a front portion (14) respectively receiving a front portion (20) of the rear shaft (2) and a rear portion (30) of the front shaft (3) by interlocking, said main shaft (1) comprising: - at least one front retaining member (6) and at least one rear retaining member (11) positioned in the inner cavity (12) so as to define together a prison (13) and each comprising a central opening (60, 110), the front portion (20) of the rear shaft (2) comprising a front end (21) extending into the central opening (110) of the rear retaining member (11), and - a connecting ring (4) located in the prison (13) and comprising a rear end (40) screwed with the front end (21) of the rear shaft (2) and extending in abut against the rear retaining member (11), the connecting member (5) being mounted in an inner cavity (32) of the front shaft (3) to cooperate by screwing with the connecting ring (4), said connecting ring (4) comprising an inner surface (42) on which is formed at least one gripping member (43) accessible from a front portion (14) of the main shaft (1) by a tool extending via the central opening (60) of the front retaining member (6), to allow the connecting ring (4) to be driven in rotation about the longitudinal axis (X) to screw it to the rear shaft (2), so that the main shaft (1) is integrally connected to the rear shaft (2).

2. Drive line (A) according to claim 1, wherein the connecting ring (4) is axially movably mounted in the prison (13) between a connecting position (P4-1) and a stand-by position (P4-2).

3. Drive line (A) according to one of claims 1 to 2, wherein the rear retaining member (11) comes from material of the main shaft (1).

4. Drive line (A) according to one of claims 1 to 3, wherein the front retaining member (6) is axially movable mounted in the inner cavity (12) of the main shaft (1) between a rear position (P6-1) and a front position (P6-2).

5. Drive line (A) according to one of claims 1 to 4, wherein the connecting member (5) comprises: - a rear end (50) extending into the central opening (60) of the front retaining member (6) and cooperating by screwing with a front end (44) of the connecting ring (4); and - a gripping member (54) accessible from a front portion (33) of the front shaft (3) by a tool, in order to allow driving the connecting member (5) in rotation about the longitudinal axis (X) to screw it to the connecting ring (4) so that the front shaft (3) is integrally connected to the main shaft (1).

6. Drive line (A) according to any of claims 1 to 5, wherein the connecting member (5) comprises a front end (52) extending abutting against a rear end (31) of the rear portion (30) of the front shaft (3).

7. Drive line (A) according to one of claims 1 to 6 having the form of an aircraft turbine engine (100) low-pressure drive line (A) configured to extend coaxially and radially inward to a high-pressure drive line (B) of the turbine engine (100), said turbine engine (100) extending longitudinally along the axis (X) and being configured to allow propulsion of the aircraft from the acceleration of an air flow (F) circulating from upstream to downstream in the turbine engine (100), the longitudinal axis (X) being oriented from upstream to downstream, the main shaft (1) in the form of a compressor shaft (1) configured to be connected to a low-pressure compressor (101) of the aircraft turbine engine (100).

8. Method for disassembling an aircraft turbine engine (100) drive line (A) according to one of claims 1 to 7, comprising: - a step of unscrewing (E2) the connecting member (5) so as to detach the connecting member (5) and the connecting ring (4) by means of a tooling inserted by a front portion of the front shaft (3) and cooperating with a gripping member (54) of the connecting member (5) in order to drive the member of connection (5) in rotation around the longitudinal axis (X), - a step of extracting (E3) the connecting member (5), - a step of unscrewing (E5) the rear end (40) of the connecting ring (4) by means of a tool inserted by the front portion (14) of the main shaft (1), extending via the central opening (60) of the front retaining member (6) and cooperating with the gripping member (43) of the connecting ring (4) in order to drive the connecting ring (4) in rotation about the longitudinal axis (X), so as to detach the connecting ring (4) and the rear shaft (2), the connecting ring (4) remaining captive in the prison (13), and - a step of extracting (E7) the front portion (20) of the rear shaft (2) from the rear portion (10) of the main shaft (1) in order to detach the main shaft (1) and the rear shaft (2).