Guide rod holder housing

Abstract

A blower hub (19) comprising a central body (17) extending axially between an upstream flank (25) and a downstream flank (26), the central body (17) having radial openings (20) each configured to hold a blower blade in position. The blower hub (19) includes an upstream annular housing (18) secured to the upstream flank (25) by a bolted connection. Figure for the abbreviation: Fig. 6

Description

Title of the invention: Guide rod holder housing Technical field

[0001] The present invention relates to “fan hub” type parts, this type of part being the equivalent of fan discs, as well as the associated manufacturing methods.

[0002] In particular, the present invention relates to the manufacture of fan hubs with bolted connection. Previous techniques

[0003] A fan hub of an aircraft engine, a type of part equivalent to the fan disc on conventional turbomachines, makes it possible to support the fan blades as well as certain bearings, the blades extending radially beyond the fan hub so as to form said fan.

[0004] The fan hub allows the transmission of engine torque to the blades, the fan hub being further connected to the engine shaft of the aircraft engine. It thus provides propulsion in conjunction with the blades and the blade setting system located at the heart of the fan hub, the blade setting system being directly connected to the root of each blade and orienting them according to an input instruction.

[0005] The fan hub is subject to major manufacturing constraints in order to guarantee the safety of the aircraft and its passengers. In particular, the mechanical properties of the fan hub must prevent any breakage of the material from which it is made and / or any other hazardous effect. The criterion of resistance to damage tolerance is one of the major criteria to be satisfied.

[0006] Broadly speaking, there are two manufacturing techniques for producing a fan hub. The first technique involves casting and shaping by conventional machining, while the second involves forging and shaping by conventional machining.

[0007] For these two techniques, the fan hub produced is in one piece and the machining is carried out in the mass obtained after casting or forging.

[0008] The first implementation method, by casting, allows the production of more complex shapes and closer to the requirements for a fan hub. This also allows optimization of the quantity of material required, and thus the reduction of costs related to the quantity of material. This technique requires little machining, the latter being only necessary to reproduce precise surfaces and interfaces, and being easily achievable. However, the performance of the material in terms of mechanical strength is not sufficient.

[0009] The second method of implementation, by forging, requires starting from a block of material whose volume is greater than that of the final product, which represents a high material cost. In addition, forging does not allow for the removal of as much material as casting or for producing optimized complex shapes, the hub obtained being then more massive. Nevertheless, forging makes it possible to obtain superior mechanical properties of the material which are necessary for the production of the fan hub: this method is necessary because it guarantees the manufacture of a fan hub meeting the safety criteria required in the aeronautical environment.

[0010] The second method has other disadvantages, such as the need to find a capable blacksmith, as well as the degradation of the properties of the material at the heart of the block of material. Indeed, this second method involves a heat treatment step of the block of material, which modifies differently the properties of the material located on the outside of the block and the properties of the material located inside, due to its excessive thicknesses. The mechanical properties of the hub material are thus reduced, harming the safety of the aircraft's flights.

[0011] The prior art according to the second method is shown briefly with the aid of figures 1 to 4, which are part of a set which will be presented later. In [Fig.l], one can see the partial section of a fan 1 installed in an aircraft engine 2. The fan 1 comprises a hub 3 whose central body 4 extends axially between an upstream flank 5 and a downstream flank 6. An upstream extension 7 extends the upstream flank 5 in one direction of the axial direction D of the hub 3, and a downstream extension 8 extends the downstream flank 6 in the other direction of the axial direction D of the hub 3. [Fig.2] shows the hub 3 in perspective, and [Fig.3] shows a subdivision of the hub 3 also in perspective. [Fig.4] shows schematically in section a block of material 9 from which a hub 3 of fan 1 is forged. From these figures, we become aware of the massive aspect of hub 3. Statement of the invention

[0012] The invention seeks to overcome the aforementioned drawbacks, and to provide a fan hub meeting the criteria for guaranteeing flight safety, and whose production cost allows its industrial production.

[0013] More specifically, the invention aims in particular to improve the mechanical strength of the hub.

[0014] The invention also aims to reduce the mass of a pitch timing system to improve the engine mass balance.

[0015] The invention also aims to limit the metallurgical health impacts on the hub.

[0016] The invention also seeks to optimize the industrialization of parts, by limiting manufacturing risks and additional industrialization costs.

[0017] Finally, the invention aims to reduce material consumption.

[0018] To do this, the invention proposes a fan hub, comprising a central body which extends axially between an upstream flank and a downstream flank, the central body having radial mouths each configured to hold a fan blade in position. The fan hub comprises an upstream annular casing secured to the upstream flank by a bolted connection.

[0019] Compared to the prior art, the invention adds a part to the central body, the annular casing, to form the hub. In other words, the upstream extension according to the prior art has been replaced in the invention by the annular casing.

[0020] Thus, the solution proposed by the invention is to assemble several parts to form a fan hub. This allows good mechanical strength, a weight saving, and easier industrialization. The separation into two parts also allows easier accessibility for machining operations before assembly.

[0021] Advantageously, the central body and the upstream annular casing are each produced independently by forging. This technique optimizes the mechanical strength of the parts.

[0022] The fan hub comprises at least two tangential force absorption yokes secured to the upstream annular casing, at least one tangential force absorption yoke being an emergency yoke. This improves the safety of the hub.

[0023] In a non-limiting manner, the tangential force absorption yoke is secured to the upstream annular casing by welding. This form of securing is rapid and strong.

[0024] Alternatively, the tangential force absorption yoke is secured to the upstream annular casing by a bolted connection. This form of fastening is removable and, therefore, facilitates maintenance.

[0025] In an alternative embodiment, the fan hub comprises at least two tangential force absorption yokes forming a single piece with the upstream annular casing, at least one tangential force absorption yoke being an emergency yoke. This embodiment is strong.

[0026] Advantageously, the central body comprises titanium. This material reinforces the mechanical resistance, the resistance to high temperatures, the resistance to corrosion. This material also contributes to lightening the hub, due to its reduced density compared to that of steel.

[0027] The present invention also relates to an aircraft engine comprising a fan hub as defined above.

[0028] The present invention also relates to a method of manufacturing a fan hub as defined above, the method comprising the following steps: - Production of the central body and the upstream annular casing from two blocks of material, - Connection of the upstream annular casing to the central body by a bolted connection.

[0029] According to the method of the invention, the step of producing the central body and the upstream annular casing is carried out by forging and comprises a heat treatment operation, the method further comprising an operation of securing at least two yokes for absorbing tangential forces to the upstream annular casing, unless the yokes form a single piece with the upstream annular casing.

[0030] The present invention in fact relates to a fan hub obtained by the method defined above. Brief description of the drawings

[0031] Other aims, characteristics and advantages of the invention will appear on reading the following description, which is non-limiting and made with reference to the appended figures, in which:

[0032] [Fig.l] which has already been mentioned, is a partial section of a fan, according to the state of the art, installed in an aircraft engine,

[0033] [Fig.2] which has already been mentioned, is a perspective view of the fan hub of [Fig.l],

[0034] [Fig.3] which has already been mentioned, is a perspective view of a subdivision of the hub of [Fig.2],

[0035] [Fig.4] which has already been mentioned, is a schematic sectional view of a block of material from which a fan hub according to the state of the art is forged,

[0036] [Fig.5] is a schematic sectional view of two blocks of material from which an annular central body and an upstream annular casing of a fan hub are forged, according to a first embodiment of the invention,

[0037] [Fig.6] is a perspective view of the fan hub according to the first embodiment of the invention,

[0038] [Fig.7] is a perspective view of a subdivision of the hub of [Fig.6],

[0039] [Fig.8] is a partial side view of the hub of [Fig.6], showing a tangential force recovery yoke secured to the upstream annular casing,

[0040] [Fig.9] is a partial view, in perspective and from the outside, of the casing of [Fig.8] with the yoke,

[0041] [Fig. 10] is a partial view, in perspective and from the inside, of a casing and a yoke forming a single piece, according to a second embodiment of the invention. Detailed description of at least one embodiment

[0042] As can be seen in [Fig. 5], a first block of material 15 and a second block of material 16 are shown schematically in radial section. The first block of material 15 is intended for the manufacture of an annular central body 17, and the second block of material 16 is intended for the manufacture of an annular casing 18. According to the invention, the central body 17 and the casing 18 are structured to be secured to each other and, as a result, to constitute a fan hub 19. The latter will be visible in other figures.

[0043] In practice, the annular central body 17 is forged from the first block of material 15, and the annular casing 18 is forged from the second block of material 16. It is observed that the radial section of the first block of material 15 reveals a radial mouth 20, configured to hold a fan blade in position.

[0044] The hub 19 is intended to be installed in a fan of an aircraft engine, the fan comprising a blade timing system positioned in the center of the hub 19. The latter notably allows the transmission of the engine torque by connecting a part transmitting the torque of the aircraft engine to the fan blades. The fan hub 19 has as its central axis D the axis of rotation of the fan.

[0045] As understood together with the aid of figures 5, 6 and 7, the axis of rotation D of the fan is also that of the hub 19, and therefore that of the central body 17 and of the casing 18. The central body 17 extends axially, along the axis D, between an upstream flank 25 and a downstream flank 26. In a non-limiting manner, the downstream flank 26 has a downstream extension 27 projecting in a direction away from the upstream flank 25. The downstream extension 27 is a peripheral subdivision of the central body 17. The downstream extension 27 is intended to be positioned towards the rear of the aircraft engine.

[0046] With particular reference to Figures 6 and 7, it is understood that the annular central body 17 has a plurality of radial mouths 20 each configured to hold a fan blade in position, the latter not being shown.

[0047] It is also understood that the upstream annular casing 18 is secured to the upstream flank 25 of the central body 17 by a screw-nut connection. This connection has the function main the maintenance of the casing 18 on the central body 17. This is to avoid the untimely separation of these elements 17, 18. The annular casing is intended to be positioned towards the front of the aircraft engine when the fan hub 19 is installed in the aircraft engine. The screw-nut connection is not detailed here, because it is well known to those skilled in the art. It is nevertheless specified that, in a non-limiting manner, the screw-nut connection comprises a series of screws which pass through the casing 18 to screw into the central body 17. The screws, not shown, are distributed around the periphery of the casing 18, and pass through holes 28 of the latter to screw into threaded orifices of the central body 17, the orifices not being visible in the figures. The screws, the holes 28 and the threaded orifices are parallel to the axis of rotation D of the hub 19.This screw-nut connection architecture facilitates the mounting of the casing 18 on the central body 18, because the screwing is obtained directly and only by action on each screw head. Screwing is a simple operation.

[0048] Alternatively, the screw-nut connection can be achieved by bolting. This means that bolts are distributed according to a diameter of the hub 19, at the junction between the casing 18 and the central body 17. The bolts are not shown. Each of these comprises a screw and a nut which is adaptable to it. The holes 28 of the casing 18 are retained, and the threaded orifices of the central body 17 are replaced by smooth holes. Thus each screw passes through the casing and the central body. Each nut is associated with a screw to tighten the casing and the central body against each other. This architecture facilitates the manufacture of the central body because, in a forged part, it is simpler to make a smooth hole than a threaded orifice. This is the consequence of the high mechanical strength of a forged part.

[0049] It is further specified that the casing 18 and the central body 17 are axially aligned. The axial positioning is again well known to those skilled in the art and not detailed here. It may for example be provided that the casing 18 and the central body 17 have complementary surfaces of revolution adapted for fitting one with the other. Surfaces of revolution with conical portions are very suitable. These surfaces guide the casing 18 and the central body 17 in a situation of alignment of their respective axes, when the screws act in a tightening direction. Alternatively, surfaces of revolution with cylindrical portions are also very suitable. It is sufficient to adopt precise manufacturing tolerances.

[0050] The fact that the hub 19 is made with two parts, the casing 18 and the central body 17, presents numerous advantages.

[0051] In particular, the forged parts 18, 17 are smaller and easier to manufacture compared to a single-piece hub according to the prior art. In this way, the invention reduces the risks inherent in manufacturing. The invention eliminates the problems linked to excess mass of the parts, reduces mechanical reductions, reduces complex machining areas, and leads to reductions in manufacturing costs. The invention further makes it possible to reduce the mass of a hub, and improves the mechanical strength of the latter. The reduction in mass of the hub 19 is also the consequence of a particular structure of the annular casing 18. Indeed, in a non-limiting manner, the latter has an openwork structure. More specifically, the casing 18 has peripheral cells 29 distributed regularly over its entire external part 30. This reduces the density of the casing 18, and consequently reduces the constraints linked to its implementation in the hub 19.

[0052] In addition, the fan hub 19 comprises a yoke 35 for absorbing tangential forces, as well as a spare yoke 36 also intended for absorbing tangential forces. The yokes 35, 36 are for example secured to the annular casing 18. If the yokes 35, 36 are here two in number, it may alternatively be provided only one or more than two.

[0053] In a non-limiting manner, as can be seen with the aid of Figures 6 to 9, each yoke 35, 36 is secured to the casing 18 by a screw-nut connection. This allows disassembly, which has the advantage of facilitating maintenance. The screw-nut connection comprises, for example, bolts 37, four in number per yoke. A bolt is the combination of a screw and a nut, each screw passing through a hole made in the yoke 35, 36 and a hole made in the annular casing 18.

[0054] Alternatively, as understood with the aid of [Fig. 10], the yokes 35, 36 are fixed to the casing 18 by linear friction welding. This technique is carried out by bringing a surface of the casing 18, facing the center thereof, into contact with a surface of each yoke 35, 36, then by linear friction of the yoke 35, 36 against the casing 18, so that the heat released by the friction of the surfaces allows the formation of a weld not visible in the figure.

[0055] Linear friction welding has the advantage of being mechanically strong, and makes it possible to reduce the mass of the hub 19 while stiffening and making the interface between the casing 18 and the yokes 35, 36 more robust.

[0056] Referring again to Figures 6 to 9, it can be seen that the yoke 35 for absorbing tangential forces comprises a body 41 at the end of which is fixed a connecting means 42. This makes it possible to mechanically connect a blade setting system, not shown, located in the center of the hub 19 at the casing 18, to prevent twisting of the blades or the fan. The tangential forces have the direction of concentric circles around the central axis D of the fan hub 19.

[0057] In the same way, the emergency yoke 36 comprises a body 43 at the end of which is fixed a connecting means 44. This makes it possible to mechanically connect the blade setting system mentioned above. The emergency yoke 36 is only used when the tangential force recovery yoke 35 is faulty.

[0058] Generally, the central body 17 and the casing 18 comprise the same materials, or different materials depending on the needs. In a particular embodiment, the central body 17 and / or the casing 18 comprises titanium.

[0059] The invention is not limited to the embodiments described, and includes all equivalents which may fall within the scope of the claims which follow.

[0060] In particular, various variants of screw-nut connection can be provided between the casing 18 and the central body 17.

Claims

Claims

1. Fan hub (19), comprising a central body (17) which extends axially between an upstream flank (25) and a downstream flank (26), the central body (17) having radial mouths (20) each configured to hold a fan blade in position, characterized in that the fan hub (19) comprises an upstream annular casing (18) secured to the upstream flank (25) by a bolted connection.

2. A fan hub (19) according to claim 1, wherein the central body (17) and the upstream annular casing (18) are each made independently by forging.

3. Fan hub (19) according to claim 1 or 2, comprising at least two yokes (35, 36) for absorbing tangential forces secured to the upstream annular casing (18), at least one yoke (35, 36) for absorbing tangential forces being an emergency yoke.

4. Fan hub (19) according to claim 3, in which the tangential force absorption yoke (35, 36) is secured to the upstream annular casing (18) by welding.

5. Fan hub (19) according to claim 3, in which the tangential force absorption yoke (35, 36) is secured to the upstream annular casing (18) by a bolted connection.

6. Fan hub (19) according to claim 1 or 2, comprising at least two yokes (35, 36) for absorbing tangential forces forming a single piece with the upstream annular casing (18), at least one yoke (35, 36) for absorbing tangential forces being an emergency yoke.

7. A fan hub (19) according to one of claims 1 to 6, wherein the central body (17) comprises titanium.

8. Aircraft engine characterized in that it comprises a fan hub (19) according to any one of claims 1 to 7.

9. Method of manufacturing a fan hub (19) according to any one of claims 1 to 7, characterized in that it comprises the following steps: - Production of the central body (17) and the upstream annular casing (18) from two blocks of material (15, 16), - Securing the upstream annular casing (18) to the central body (17) by a bolted connection.

10. Method according to claim 9, in which the step of producing the central body (17) and the upstream annular casing (18) is carried out by forging and comprises a heat treatment operation, the method further comprising an operation of securing at least two yokes (35, 36) for absorbing forces tangential to the upstream annular casing (18), unless the yokes (35, 36) form a single piece with the upstream annular casing (18).

Images