Fused soft and hard bearing rings

Abstract

The present invention relates to an enclosure (26) for a turbine (10), comprising a turbine drive shaft (16) rotating about a longitudinal axis (X) via two rolling bearings (22, 24), the two rolling bearings being an upstream bearing (22) and a downstream bearing (24), the two rolling bearings each comprising an inner ring (28a, 28b) carried by the drive shaft (16), the enclosure (26) being characterized in that the two bearings (22, 24) share a single integral outer ring (35), the single outer ring (35) having an upstream end (36a) and a downstream end (36b), the upstream end (36a) and the downstream end (36b) being connected to each other by a stud section (34), the single outer ring (35) also being carried by an upstream base plate (38a) and a downstream base plate (38b) of a bearing support (40), the bearing support being capable of being attached to a fixed structure of the turbine (10).

Description

Technical Field

[0001] The present invention relates to the field of turbine bearing enclosures, in particular to the outer ring of a drive shaft bearing.

[0002] The present invention belongs to the general field of aircraft turbomachines. Background Art

[0003] The prior art is shown by document US-A1-2013 089 284.

[0004] In a traditional and well-known manner (cf. Figure 1 ), an aircraft turbofan engine 10 comprises a fan 12, which may be connected to a reducer 14, which itself is connected to a drive shaft 16 extending along an axis of rotation X. This drive shaft 16 in particular rotates a low-pressure turbine 20. The low-pressure turbine 20 is located downstream of the high-pressure turbine 18 and is illustrated at the rear of the turbine 10. The low-pressure turbine 20 is usually rotated by the drive shaft 16 via rolling bearings 22, 24. These rolling bearings 22, 24 are located in an enclosure 26, referred to as the rear enclosure of the turbine. This rear enclosure 26 is in the present application Figure 1 Highlighted in.

[0005] The rear enclosure 26 typically has an axial length of approximately 400 mm.

[0006] Typically and as Figure 2 As shown, the rear enclosure 26 includes two rolling bearings 22, 24, namely an upstream bearing 22 and a downstream bearing 24, each bearing 22, 24 including an inner ring 28a, 28b and an outer ring 29a, 29b. The inner rings 28a, 28b are carried by the drive shaft 16 of the turbine 10. The upstream outer ring 29a is usually connected to a first bearing support 32a (upstream bearing support) via a support ring 30 of an upstream central damping fluid film (squeeze film), and the downstream outer ring 29b is connected to a second bearing support 32b (downstream bearing support) via a support ring 30 of a downstream central damping fluid film, as shown. Figure 2 As shown. The first bearing support 32a comprises a first upstream flange 100a intended to be attached to and cooperate with a first downstream flange 100b of the second bearing support 32b. This cooperation is performed using conventional attachment means F known to those skilled in the art. The first bearing support 32a comprises a second flange (not shown) intended to be attached to and cooperate with a first flange 26a (upstream flange) of the enclosure 26 and a flange S of the fixing structure of the turbine 10 (see Figure 1) are attached to cooperate. Finally, the first bearing support 32a comprises a third flange 101 intended to attach and cooperate with the flange 33 of the outer ring 29a. The second bearing support 32b comprises a second support flange 102 intended to attach and cooperate with the second flange 26b (downstream flange) of the enclosure 26 by means of attachment means F. The prior art device thus has a total of nine flanges S, 33, 100a, 100b, 101, 102, 26a, 26b (as well as flanges not shown) which make it possible to connect the upstream bearing support 32a and the downstream bearing support 32b to the fixed structure of the turbine 10.

[0007] The principle of a soft bearing with a central damping fluid film is to impart radial damping to the bearing. This flexibility is imparted by the stud segments and centering, and is typically combined with a flange for axial locking. The radial damping of the bearing by the fluid damping film itself will not be explained in this application, as this technology is well known to those skilled in the art. Specifically, dynamicists can individually adjust the flexibility of each bearing by calculating the dimensions of the stud segments (including size and length).

[0008] The disadvantage of the rear enclosure 26 in the prior art is the overall axial size of the rear enclosure. The axial size of the rear enclosure 26 is mainly due to the constraints imposed by the total power. In fact, there is flexibility (the flexibility provided by the stud section 34, see Figure 2 ) are integrated into the enclosure 26, which requires that each bearing 22, 24 have an incompressible axial length. In addition, again for reasons of overall dynamics, these bearings 22, 24 have a minimum distance between the bearings to be respected.

[0009] The present invention aims in particular to propose an enclosure having reduced overall axial dimensions without impairing the overall dynamics, ie without affecting the flexibility (and therefore the length of the stud) and without affecting the distance between the two bearings. Summary of the Invention

[0010] This is achieved according to the invention by a turbine enclosure comprising a turbine drive shaft rotatable about a longitudinal axis X by means of two rolling bearings, one upstream and one downstream, each comprising an inner ring carried by the drive shaft. According to the invention, the two bearings share a single, one-piece outer ring comprising an upstream end and a downstream end connected to one another by a stud section, the single, one-piece outer ring also being carried by an upstream and downstream baseplate of a bearing support adapted to be attached to a fixed structure of the turbine.

[0011] The solution thus makes it possible to achieve the above-mentioned objectives. In particular, both bearings have a single outer ring. On the one hand, this makes it possible to reduce the number of components in the enclosure. This also has an impact on the design of the rolling bearing support, since the outer ring makes it possible to remove two of the three flanges. This minimizes the overall dimensions of the enclosure in terms of thickness and length, while saving time, costs and simplifying installation by reducing the number of components. All this while maintaining the functions associated with the bearing. The reduction in the number of flanges also makes assembly more difficult.

[0012] The enclosure according to the present invention may include one or more of the following features, taken alone or in combination with each other:

[0013] - the upstream end of the single, integral outer ring has a radially outer surface shrink-fitted onto the radially inner surface of the upstream base plate,

[0014] - the upstream end of the single integral outer ring cooperates with the upstream base plate of the bearing support to provide a centering function for the single outer ring,

[0015] - axially blocking the single-piece outer ring by means of a stop ring or by bolting its upstream end to the upstream base plate of the bearing support,

[0016] - a support ring for the damping fluid film is arranged radially between the downstream end of the single monolithic outer ring and the base plate of the downstream bearing support, the support ring and the downstream end forming a chamber intended to receive the damping fluid,

[0017] - the distance dP between the upstream bearing and the downstream end of the enclosure is between 250 mm and 300 mm,

[0018] - the bearing support has an upstream wall carrying the upstream baseplate and a downstream wall carrying the downstream baseplate, the upstream wall and the downstream wall being connected to the wall of the enclosure by means of external flanges cooperating with the first flange of the wall of the enclosure,

[0019] - the downstream end of the single integral outer ring is axially retained downstream by a retaining plate and axially retained upstream by an upstream retainer arranged on the downstream base plate,

[0020] - the enclosure is formed at least partially by the exhaust casing,

[0021] -The upstream bearing is what is called a hard bearing,

[0022] -The downstream bearing is a so-called soft bearing,

[0023] The invention also relates to an aircraft turbomachine comprising at least one enclosure according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will be better understood and other objects, details, features and advantages of the invention will become clearer on reading the following detailed illustrative description of an embodiment of the invention given as a purely illustrative and non-limiting example with reference to the accompanying schematic drawings.

[0025] In these drawings:

[0026] [ Figure 1 ] Figure 1 is a schematic longitudinal cross-sectional view of an aircraft turbine to which the present invention is applied,

[0027] [ Figure 2 ] Figure 2 is a schematic longitudinal cross-sectional view of a turbine rear enclosure according to the prior art,

[0028] [ Figure 3 ] Figure 3 is a schematic longitudinal cross-sectional view of a turbine enclosure according to a first embodiment of the present invention,

[0029] [ Figure 4a ] Figure 4a This is an enlarged view of the upstream bearing according to the previous figure.

[0030] [ Figure 4b ] Figure 4b is based on Figure 3 Magnified view of the downstream bearing,

[0031] [ Figure 5 ] Figure 5 is a schematic longitudinal cross-sectional view of a turbine enclosure according to a second embodiment of the present invention,

[0032] [ Figure 6 ] Figure 6 is a perspective view of a stop ring according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0033] In this detailed description, in order to simplify reading and understanding of the present invention, the same reference numerals will be used for components and parts having the same functions as those in the prior art.

[0034] Figure 3 The enclosure 26 is shown to include a drive shaft 16 that rotates about a longitudinal axis X. The drive shaft 16 may be a low-pressure shaft of the turbine 10 . Two rolling bearings 22 , 24 are connected to the drive shaft 16 , an upstream bearing 22 and a downstream bearing 24 . Figure 3The enclosure considered in FIG is the rear enclosure of the turbine 10, more specifically the exhaust casing of this turbine 10. However, contrary to the prior art, the two rolling bearings 22, 24 of the enclosure 26 share a single integral outer ring 35 (one-piece). In fact, Figure 2 The outer rings 29a, 29b have been fused.

[0035] The single outer ring 35 is generally cylindrical in shape and extends along the axis X. The single outer ring 35 includes an upstream end 36 a and a downstream end 36 b connected to the center of the single outer ring 35 by a stud section 34 .

[0036] The single outer ring 35 is carried at its ends 36a, 36b by two bearing support baseplates 38a, 38b, respectively located upstream and downstream, each of which is attached to a fixed structure of the turbine 10. Consequently, whatever the embodiment, the number of flanges of the bearing support is reduced: in fact, the invention makes it possible to remove one or two flanges, which leads to a simplification of the manufacture of the bearing supports 22, 24 and a simplification of the assembly of the enclosure 26. The bearing supports 22, 24 can be obtained directly by casting or by additive manufacturing. The removal of the various flanges / flange pairs from the prior art also provides greater rigidity to the bearing supports 22, 24, since a pair of flanges provides flexibility in the mechanical element.

[0037] The upstream end 36a engages with the inner ring 28a of the upstream bearing 22 via rollers. As previously described, the inner ring 28a is carried by the drive shaft 16. The upstream end 36a of the single outer ring 35 is connected to the upstream end of the main bearing support 40, which forms the upstream bearing support base plate 38a. The downstream end 36b of the single outer ring 35 engages with the inner ring 28b of the downstream bearing 24 via rollers. As previously described, the downstream inner ring 28b is carried by the drive shaft 16. The downstream end 36b of the single outer ring 35 is connected to the downstream end of the main bearing support 40, which forms the downstream bearing support base plate 38b. Thus, the two base plates 38a, 38b are connected to the wall of the enclosure 26 via the main bearing support 40, which is unique to this embodiment.

[0038] The flanges 100a, 100b of the prior art are no longer present. The main bearing support 40 now has only two attachment flanges:

[0039] an external flange (not shown) intended to engage with a first flange 26a (upstream flange) of the wall of the enclosure 26 and with a flange S ( Figure 1 shown in ) attached to fit,

[0040] - an internal flange 400 intended to engage with the second flange 26b (downstream flange) of the enclosure 26 (see Figure 3)Attachment fit.

[0041] Specifically, the bearing support 40 includes an upstream wall 40a that supports the upstream base plate 38a and a downstream wall 40b that supports the downstream base plate 38b. The upstream wall 40a and the downstream wall 40b are connected to the wall of the enclosure 26 via external flanges that mate with the first flange 26a of the wall of the enclosure 26. The upstream wall 40a and the downstream wall 40b form a single component with the bearing support 40. The upstream wall 40a is spaced apart from the downstream wall 40b. This configuration of the bearing support 40 reduces the number of components and simplifies the turbine 10.

[0042] The three flanges S, 400, 26A are attached together by conventional attachment means F known to those skilled in the art.

[0043] The number of accessory flanges is significantly reduced. This means a significant space saving. In fact, in the present invention, there are two flanges 400, one internal and one external, of the bearing support 40, two flanges 26a, 26b of the enclosure 26 and a flange S of the fixed support of the turbine 10.

[0044] So we have five flanges, which is a reduction in the number of flanges used compared to the nine flanges of the prior art.

[0045] There is also a strong axial gain: the fusion of the two outer rings into a single outer ring 35 in fact makes it possible to reduce the overall axial dimensions of the enclosure 26. In fact, the axial distance dP separating the upstream bearing 22 from the downstream end of the enclosure 26 (defined by the radial wall 43), taken along the axis X (considering the central axis of the bearing), is reduced from a length of about 400 mm to a length of between about 250 and 300 mm (see Figure 3 ).

[0046] In addition, the upstream bearing 22 is a hard bearing and the downstream bearing 24 is a soft bearing. Since the upstream bearing is now "hard" (instead of soft as in the prior art), the overall dynamics are improved, which also helps to simplify installation.

[0047] More specifically, downstream bearing 24 is a bearing on a damping fluid film support ring 30, which is centered by means of a central stud section 34. This central stud section allows adjustment of the position of downstream bearing 24 relative to upstream bearing 22, which is clamped to an upstream bearing support base plate 38a. Damping fluid film support ring 30 is radially arranged between the downstream end 36b of the single outer ring and the downstream bearing support base plate 38b. This results in a soft downstream bearing 24.

[0048] The support ring 30 and the downstream end 36b form a chamber for receiving a damping fluid. More specifically, the downstream end 36b of the single outer ring 35 comprises two annular grooves g, each receiving a seal making it possible to axially delimit a chamber. The damping fluid is, for example, oil.

[0049] The centering of the single outer ring 35 is performed by the cooperation between the upstream end portion 36a and the upstream bearing support base plate 38a. Figure 3 In the embodiment of FIG. 3 , the upstream end portion 36 a of the single outer ring 35 is bolted to the upstream bearing support base plate 38 a by bolts B. In practice, as Figure 3 and Figure 4a As shown, it can be seen that the upstream end 36a of the single outer ring 35 is equipped with a flange C. This centering flange C extends radially from the outer surface of the upstream end 36a toward the outside of the turbine 10. This centering flange C is held in a clamping fit with the upstream bearing support base plate 38a by bolts B. The upstream bearing 22 is thus attached to the main bearing support 40 and, therefore, to the static structure of the turbine 10.

[0050] On the other hand, the downstream bearing 24 remains soft to meet the overall power requirement. The required softness is achieved by the stud section 34 and the damping fluid film support ring 30 of the downstream bearing 24.

[0051] In the event of a breakage of the stud segment 34, the downstream end 36b of the single downstream outer ring 35 is axially retained downstream by the retaining plate 42 and axially retained upstream by an upstream retainer 44 arranged on the downstream base plate 38b (see Figure 4b A retaining plate 42 is supported on the downstream bearing support base plate 38b. The retaining plate 42 includes openings for bolts B that allow the retaining plate 42 to be secured to the base plate 38b of the bearing support 40. The retaining plate 42 extends radially to the downstream end 36b of the single outer ring 35, forming an axial stop. The upstream retainer 44 is formed, for example, by an attachment to the downstream base plate 38b. The attachment extends upstream of the downstream base plate 38b.

[0052] exist Figure 5 In the illustrated embodiment, the downstream end 36b of the single outer ring 35 has an external groove 46 forming a tongue-and-groove, which cooperates with the retaining plate 42 forming a tongue by forming a depression. In the event of a breakage of the stud section 34, the single outer ring 35 is axially held in place by the external groove 46. A rotation stop (not shown) may optionally be integrated into any embodiment.

[0053] exist Figure 5In the same embodiment shown, the upstream end 36a of the single outer ring 35 is axially held against the upstream base plate 38a by a stop ring 48. The main bearing support 40 is fitted into the flange C of the single outer ring 35. For example, the upstream base plate 38a comprises a groove that receives the flange C. The stop ring 48 ensures the axial locking of the single outer ring 35. The stop ring 48 is capable of withstanding high axial loads. Ring-shaped parts.

[0054] In fact, the very high hardness of this type of ring element satisfies the strong demands on the mechanical strength of the single outer ring 35. Figure 6 As shown, the stop ring 48 may be helical and comprise two superimposed layers of wound metal strips. This double winding set enables the stop ring 48 to increase its resistance to axial loads.

[0055] like Figure 6 As shown, the stop ring 48 is made of carbon steel in particular. The stop ring 48 has a thickness e measured along the axis of the stop ring 48, which is between 2.5 mm and 4.5 mm, preferably between 3.5 mm and 4 mm. The stop ring 48 is housed, for example, in a groove provided in the upstream base plate 38 a. The stop ring 48 is supported on the flange C of the single outer ring 35. Preferably, the groove is wider than the thickness of the stop ring 48. This thickness of the stop ring 48 allows it to withstand high axial loads compared to rings of the prior art. Preferably, the stop ring 48 has an outer diameter D between 150 mm and 190 mm.

[0056] It can thus be seen that, whatever the embodiment considered, the present invention provides the following advantages:

[0057] - Reduced number of parts, thus saving time during installation and cost during production,

[0058] - a reduction in the number of support flanges, resulting in an improvement in the stiffness of the support of the bearing (and an improvement in mass associated with this reduction),

[0059] - compression of the enclosure, resulting in a reduction in the overall axial dimensions of the enclosure (and an improvement in quality associated with this reduction in overall dimensions),

[0060] -Adapt to the total power sought.

Claims

1. An enclosure (26) for a turbine (10), comprising a turbine drive shaft (16) rotatable about a longitudinal axis (X) via two rolling bearings (22, 24), the two rolling bearings being an upstream bearing (22) and a downstream bearing (24), the two rolling bearings each comprising an inner ring (28a, 28b) carried by the turbine drive shaft (16), The enclosure (26) is characterized in that The two rolling bearings (22, 24) share a single integral outer ring (35), the single integral outer ring (35) comprising an upstream end (36a) and a downstream end (36b), the upstream end (36a) and the downstream end (36b) being connected to each other by a stud section (34), The enclosure further comprises a bearing support (40) adapted to be attached to a fixed structure of the turbine (10) and comprising: upstream substrate (38a), a downstream base plate (38b), said upstream base plate (38a) and said downstream base plate (38b) carrying said single integral outer ring (35), an upstream wall (40a) carrying the upstream substrate (38a), and A downstream wall (40b) carries the downstream base plate (38b), the upstream wall (40a) and the downstream wall (40b) are connected to the wall of the enclosure (26) by an external flange that cooperates with the first flange (26a) of the wall of the enclosure (26).

2. The enclosure (26) for a turbomachine (10) according to claim 1, characterized in that The upstream end portion (36a) of the single integral outer ring (35) has a radially outer surface that is shrink-fitted onto the radially inner surface of the upstream base plate (38a).

3. The enclosure (26) for a turbomachine (10) according to claim 1 or 2, characterized in that The upstream end portion (36a) of the single integral outer ring (35) cooperates with the upstream base plate (38a) of the bearing support (40) to provide a centering function for the single integral outer ring (35).

4. The enclosure (26) for a turbomachine (10) according to claim 3, characterized in that The single integral outer ring (35) is axially blocked by a stop ring or by bolting the upstream end (36a) of the single integral outer ring (35) to the upstream base plate (38a) of the bearing support (40).

5. The enclosure (26) for a turbomachine (10) according to claim 1 or 2, characterized in that A support ring (30) for the damping fluid membrane is arranged radially between the downstream end (36b) of the single integral outer ring (35) and the downstream base plate (38b) of the bearing support (40), the support ring (30) and the downstream end (36b) forming a chamber intended to receive the damping fluid.

6. The enclosure (26) for a turbomachine (10) according to claim 1 or 2, characterized in that The upstream bearing (22) is separated from the downstream end (43) of the enclosure (26) by a distance (dP) between 250 mm and 300 mm.

7. An enclosure (26) for a turbomachine (10) according to claim 1 or 2, characterized in that The downstream end portion (36b) of the single integral outer ring (35) is axially retained downstream by a retaining plate (42) and axially retained upstream by an upstream retainer (44) arranged on the downstream base plate (38b).

8. An enclosure (26) for a turbomachine (10) according to claim 1 or 2, characterized in that The enclosure (26) is formed at least in part by the exhaust casing.

9. An aircraft turbomachine (10) comprising at least one enclosure (26) for a turbomachine (10) according to any one of claims 1 to 8.

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