EP1617046B1 - Shaft and bearing assembly - Google Patents

Description

The present invention relates to an assembly comprising a shaft or a rotating shaft portion about its axis and a rolling bearing by which it is supported. The present invention applies in particular to the mounting of a bearing for a turbine shaft a gas turbine engine.

FIG. 1 shows a partial view of a gas turbine engine 1. The high pressure turbine rotor 2 is immediately downstream of the combustion chamber 3 and is rotated by the action of the gases which are derived from the blades 4 mounted on the disk 5 of the rotor 2. The turbine disc 5 is integral with a pin 6, disposed downstream relative to the direction of the gas flow. At the end of the pin 6 is mounted a bearing by which the rotating assembly is supported. Here is shown only the inner ring 8 of the bearing. The rotor 2 is integral upstream of a drum 7 connected to the high pressure compressor, not shown, itself rotated by an upstream bearing. This rotating assembly forming the high pressure body of the engine is supported by means of these two bearings either by the fixed structure of the engine in the case of a single-body engine or by another rotating assembly in the case of a double or triple body motor for independent low pressure or intermediate pressure stages.

In current engines, the inner ring is secured to the shaft or journal by hooping. By this operation the ring is mounted with clamping on the shaft or trunnion. The coupling can thus both withstand the rotational torques to which the ring is subjected during engine operation as axial forces. A nut 9 downstream, screwed on the pin and locked in rotation, locks the ring 8 in position and ensures cohesion of the assembly in case of occurrence of a loss of clamping thereof on the trunnion following, for example , wear on the surfaces in contact or overheating of the components. To cover all the cases of failure and avoid an incident it is necessary to oversize the nut to be able to print a high tightening torque on all. Such an assembly is disclosed in the document FR 2 629 537.

This solution therefore has the disadvantage of a significant mechanical loading parts. The size of the nut in particular is related to the load requested. It follows the need to design and implement heavy and complex tools with means of multiplying forces.

Furthermore, it would be desirable for certain applications, particularly in the case of new more compact engines, to reduce the axial size of the shaft supporting the turbine, with its bearing. Since the position of the bearing itself is perfectly defined in its environment with respect to the other engine components such as the fixed structure, only the part comprising the nut could be modified. However, given the constraints mentioned above, it is not possible to reduce the size of the nut without reducing the mechanical strength of the assembly.

To solve this problem, it was first proposed to remove the nut and directly solder the ring to the shaft. This solution, however, would not be suitable, for certain engines, because of the different materials constituting these two components, corrosion problems that would result, and the complexity of operations when later it would be necessary to intervene on the part.

US-A-5,863,137 discloses another form of coupling according to the state of the art.

The applicant has therefore set as a first objective a method of assembling a rolling bearing ring, the shaft on which it is mounted to overcome these disadvantages by providing the same mechanical characteristics as those proposed by a nut .

The applicant has also set as another objective the realization of a method of assembling a rolling bearing ring on a shaft, which is both easy to assemble and disassemble.

The invention solves this problem with an assembly according to claim 1 and comprising a rotary shaft and a rolling bearing, the bearing comprising a ring integral with the shaft and forming a raceway for the bearing members of the bearing, characterized by the that the ring is immobilized in rotation on the shaft by a coupling consisting of a plurality of teeth on the shaft cooperating with tenons integral with the ring, the tenons being housed between said teeth, and in the axial direction by a transverse rod in the form of a ring portion.

The term "shaft" designates a shaft, a shaft portion, a trunnion or more generally any part on which a rolling bearing is mounted. Whereas, in the case of a bearing assembly at the end of the trunnion on the side of its free end, the nut, because of the assembly constraints, must be placed in abutment against the ring on its edge near the end free of the trunnion, can be arranged a clutch coupling on the opposite side relative to the free end. The corresponding portion of the trunnion can thus be shortened. Furthermore, advantageously, the axial retaining means can be associated with the clutch coupling.

Advantageously, the coupling consists of a plurality of teeth, respectively tenons, spaced apart from each other along the circumference of the shaft. The number of teeth and associated tenons, as well as the size thereof, are determined by the circumferential loads that the coupling is called to support during the operation of the engine. To avoid unbalance, it advantageously has the elements symmetrically around the axis of the shaft.

It is understood that the solution applies both to the mounting of an inner bearing ring on the outer surface thereof, and the mounting of an outer bearing ring on a shaft inside thereof when it is hollow.

The rolling bearing can be any, ball, roller or other. In a simplified manner, a bearing comprises at least two concentric rings: an inner ring and an outer ring, between which are arranged a plurality of rolling members, for example rollers, held apart from each other by a cage. The rings each define a rolling track for the rolling members

According to another characteristic, the ring is made of an elastic material. It takes a first form in radial extension and where it constitutes said axial retention between the shaft and the ring, and a radially retracted form where it allows the axial displacement of the ring relative to the shaft. According to the preferred embodiment, in the retaining position, the rod is arranged to be in contact with both a tooth and at least one tenon.

According to a characteristic, the shaft comprises a cylindrical portion forming an outer radial abutment of the free end of the tenon or tenons.

• La figure 1 représente, en coupe axiale, une partie d'un moteur à turbine à gaz montrant un rotor de turbine et le tourillon avec une bague de palier montée conformément à l'art antérieur,
• La figure 2 montre, en coupe axiale, un tourillon avec une bague interne de palier à roulement montée conformément à l'invention,
• La figure 3 montre, en perspective, une vue partielle de la bague interne de la figure 2 détaillant les tenons,
• La figure 4 montre, en perspective, le tourillon de la figure 2 avec les dents de l'accouplement à crabots,
• La figure 5 montre la mise en place d'un jonc annulaire sur le tourillon de la figure 4,
• La figure 6 montre, en perspective, la bague montée sur le tourillon de la figure 2,
• La figure 7 montre un détail agrandi de la figure 6.

Other features and advantages will emerge from the following description of an embodiment of the invention, accompanied by the appended drawings in which:

• FIG. 1 represents, in axial section, a part of a gas turbine engine showing a turbine rotor and the journal with a bearing ring assembled according to the prior art,
• FIG. 2 shows, in axial section, a journal with an inner bearing ring mounted in accordance with the invention,
• FIG. 3 shows, in perspective, a partial view of the inner ring of FIG. 2 detailing the tenons,
• FIG. 4 shows, in perspective, the pin of FIG. 2 with the teeth of the clutch coupling,
• FIG. 5 shows the placement of an annular ring on the pin of FIG. 4,
• FIG. 6 shows, in perspective, the ring mounted on the pin of FIG. 2,
• Figure 7 shows an enlarged detail of Figure 6.

FIG. 2 shows a pin 16 or a turbine shaft connected to the turbine rotor, not shown, according to the invention. Figure 6 partially shows a representation of the arrangement of Figure 2 perspective view. The trunnion comprises a flange with bores 161 by which is bolted to 161 the turbine rotor. There is a cylindrical portion 163 of axis of rotation that the shaft, provided with elements such as wipers forming with complementary elements not a labyrinth seal. The trunnion also comprises a straight cylinder 162 for mounting an inner rolling bearing ring 18. The ring 18 comprises an inner cylindrical member 181 on the cylindrical portion 162 of the trunnion. The track 182 comprises an outer bearing for the rolling members, here rollers, not shown, as well as the rest of the bearing. A in the figure, the ring is extended, along the common axis of the ring and the shaft, by tenons 17. These tenons 17 are clearly visible in Figure 3 which is a partial perspective view of the ring 18 Each tenon has an internal groove 171, facing the axis of the ring and transversely thereto. The tenons are distributed here over the entire ring 17 with a determined spacing corresponding to the width of the teeth described below.

The ring 18 is abutted by the surface 172, oriented transversely to the axis, against an axial abutment 167 formed on the cylindrical portion 162. The surface 172 is clearly shown in Figure 4 showing the end of the trunnion in a view in perspective, in isolation. Radial teeth 164 are disposed at the periphery thereof, being spaced apart from each other with a spacing corresponding to the width of the tenons 17. Thus, in the position of FIG. 2, the tenons 17 are placed between the teeth 164, the ring being supported by the face 172 against the face 167 forming a stop. The ring 18 and the trunnion 16 thus form a dog clutch coupling. By this coupling the ring is firmly immobilized in rotation, even if the tightening of the ring on the shaft is weakened.

The teeth are aligned transversely to the axis of the shaft and provide a transverse groove 166, radially open, the opposite side to that of the faces 165. When the ring bears against the face 167, the groove 166 is screwed to grooves 171 formed on the tenons 17. In the assembly of Figure 2, a ring 19, transverse to the axis, is housed in the continuity of the grooves 171, and forms said axial retaining means. Indeed, being housed in all the grooves 171, its height is sufficient to engage against all the teeth 164. As seen in Figure 2, it prevents any withdrawal movement of the ring towards the right on the figure. We see in Figure 7 which shows an enlarged detail of Figure 6, the rod 19 in the locking position. This ring has a rectangular section here. It extends on the circumference. It forms a ring with a missing portion. It is elastic, preferably metal, and can be retracted by appropriate means to be housed in the groove 166 of the pin. When it is in this last position, it does not interfere with the axial movement of the ring. The depth of the groove 166 is sufficient to accommodate the rod and retract completely relative to the tenons of the ring.

As can be seen in FIGS. 2, 6 and 7, the free portion of the tenons 17 is engaged in a downstream axial groove formed between the cylindrical portion 163 and the surface of the cylindrical trunnion portion. The pins 17 are in external radial support against the surface of this cylindrical portion 163. Since the assembly is capable of rotating at very high speeds of rotation, the radial support provided by the element 163 reduces the deformations and stresses due to centrifugal forces exerted on the tenons. This considerably increases the durability of the parts.

When mounting the ring 18 on the trunnion 16, the rod is first fitted by sliding it behind the teeth 164, as shown in FIG. 5; it is elastic enough to be deformed. Then, by means of a suitable tool the ring is forced to retract into the groove 166. While holding the ring in this position, the ring is slid along the cylindrical portion 162, until the faces 172 of the ring abut against the surface 167. The engagement of the tenons between the teeth forming a dog clutch coupling. Then relaxes the ring which relaxes and is housed in the grooves 171, axially locking the ring 18.

For disassembly, there is provided an annular notch 20 through which one can extract the ring by means of a suitable tool. It is also observed that it is easy to introduce a tool between the teeth 164 to retract the rod 19.

It has been described as a bearing ring of a rolling bearing. The invention applies equally well, mutatis mutandis, to the mounting of the outer ring of a rolling bearing on the inner surface of a shaft or a housing structure. Furthermore, the claw coupling can be made in the teeth and hold them on the ring and the second secured to the shaft. In particular the invention is not limited to mounting a ring on a turbine shaft, it is more general scope.

Claims (6)

1. An assembly composed of a rotary shaft and of a roller bearing supporting said shaft, the bearing including a ring (18) interconnected with the shaft (16) and forming a raceway for the bearing, the ring (18) being immobilised in rotation on the shaft (16) by a coupling formed by a plurality of teeth (164) on the shaft (16) co-operating with lugs (17) interconnected with the ring (18), the lugs (17) being received between said teeth (164), and in axial direction by a transversal snap ring (19) characterised in that the transversal snap ring (19) is in the form of a ring portion.
2. An assembly according to claim 1 whereof the snap ring is made of a plastic material and takes on a first radially extended shape where it forms an axial retention and a radially retracted shape where it enables the axial displacement of the ring (18) relative to the shaft.
3. An assembly according to one of the claims 1 and 2 whereof the shaft (16) comprises a cylindrical portion (163) forming an external radial stop of the free end of the lug(s) (17).
4. An assembly according to one of claims 1 to 3 whereof the ring (18) is the internal ring of the roller bearing and is installed on the outer surface of the shaft.
5. An assembly according to one of the previous claims whereof the shaft (16) is a gas turbine engine shaft.
6. An assembly according to one of previous claims whereof the shaft is a turbine journal in an engine fitted with two spools at least.

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