WO2016128659A1

WO2016128659A1 - Bearing mounted with a two-part outer ring pressing against an abutment of the housing by means of a spring exerting an axial preload

Info

Publication number: WO2016128659A1
Application number: PCT/FR2016/050263
Authority: WO
Inventors: Sébastien BOUFFLERT; Alban Lemaitre; Philippe Bourdin; Fabien Tessier
Original assignee: Snecma
Priority date: 2015-02-09
Filing date: 2016-02-08
Publication date: 2016-08-18
Also published as: FR3032481B1; FR3032481A1

Abstract

The invention relates to a bearing for a rotating machine in an axial direction (Z-Z), comprising an inner ring (3) mounted around a shaft (1) and an outer ring (4) mounted in a housing (2), bearing elements (5) being arranged between said inner ring and said outer ring, characterised in that the outer ring (4) comprises a first half-ring and a second half-ring (4A, 4B), the first half-ring (4A) being locked against translation in the axial direction in relation to the housing (2), the second half-ring (4B) being mounted in a sliding manner in a receiving area between the first half-ring (4A) and an abutment (21) of the housing (2), the abutment (21) of the housing (2) comprising a preload member (7) exerting a pushing force on the second half-ring (4B) with the effect of positioning same such that it presses against the first half-ring (4A).

Description

MOUNTED BEARING WITH A TWO-PIECE EXTERIOR RING IN SUPPORT AGAINST

A CRASH OF THE CARTER THROUGH A SPRING EXERCISING AN AXIAL PRELOAD

GENERAL TECHNICAL FIELD

5

The present invention relates to the field of rotating machines, and more specifically the bearings for rotating machines.

STATE OF THE ART

0

Rotating machines, and especially turbopumps used in space applications, require having one or two axial stops and one or more bearings for the radial suspension of the rotor of the rotating machine.

Bearing pairs are thus commonly used, performing both a bearing function for the rotor and axial stops. Three-point ball bearings can also be used. 0 Some rotating machines, including turbopumps, are designed with an axial balancing system called "active" allowing it to balance the forces without an axial stop must take the differential load of axial up to several tons. It is then necessary that the bearings can allow the shaft to slide5 so that the balancing system can be activated. The doublets of bearings make it possible to perform this function, whereas a bearing alone does not allow sufficient sliding.

Although the doublets of bearings make it possible to perform the desired functions, they nevertheless have disadvantages, in particular in terms of space and mass, which are highly detrimental especially for space applications. The present invention thus aims to obtain the advantages and functionalities of a bearing doublet by means of a single bearing. PRESENTATION OF THE INVENTION

For this purpose, the present invention proposes a bearing for rotating machine in an axial direction, comprising an inner ring mounted around a shaft and an outer ring mounted in a housing, between which rolling elements are arranged,

characterized in that the outer ring comprises a first and a second half-rings,

the first half-ring being fixed in translation in the axial direction relative to the housing,

the second half-ring being slidably mounted in a housing between the first half-ring on the one hand, and a stop of the housing on the other hand, the abutment of the casing comprising a pre-load member exerting a thrust force on the second half-ring tending to position it in support against the first half-ring.

The pre-load member typically defines a threshold value of axial force so that, when an axial force greater than this threshold value is exerted in opposition to the thrust force exerted by the pre-load member, the second half-ring is no longer in axial abutment against the first half-ring.

The first half-ring typically comprises a base provided with an indexing element so as to immobilize the first half-ring in translation in the axial direction relative to the housing, said base bearing against the abutment of the housing, the second half-ring being disposed between the base of the first half-ring and the rolling elements. According to a particular embodiment, the first half-ring is formed by machining the housing.

The first half-ring and the abutment of the housing define for example a maximum axial displacement of the second half-ring less than 2 mm.

The invention also relates to a spacecraft turbo pump comprising a bearing as defined above.

PRESENTATION OF FIGURES

Other features, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and nonlimiting, and which should be read with reference to the appended figures, in which:

- Figure 1 shows an example of a bearing according to one aspect of the invention;

- Figure 2 shows the bearing of Figure 1 according to another configuration;

- Figures 3 and 4 show another embodiment of an aspect of the invention, in the configurations corresponding to Figures 1 and 2 respectively.

In all the figures, the elements in common are identified by identical reference numerals.

DETAILED DESCRIPTION

Figures 1 and 2 show an example of a bearing according to one aspect of the invention, in two different configurations.

These figures show a rotating machine shaft 1 mounted in a casing 2. The shaft 1 is rotatably mounted relative to the housing 2, or vice versa; the rotating machine is thus typically a machine with rotating casing or fixed casing.

The rotation of the rotating machine is in an axial direction defined by the shaft 1, and shown schematically in the figures by a Z-Z axis.

A bearing is disposed between the shaft 1 and the housing 2, thus ensuring the rotation of the shaft 1 relative to the housing 2 or vice versa.

The bearing comprises an inner ring 3 mounted around the shaft 1, and an outer ring 4 mounted in the casing 2, between which are disposed rolling elements 5, typically balls, held in a cage 6. The inner ring 3 is fixed in translation in the axial direction relative to the shaft 1. In the embodiment shown in the figures, the inner ring 3 is disposed between a shoulder 11 of the shaft 1 on the one hand, and a sleeve 12 mounted around the shaft 1 on the other hand, it being understood that other means of immobilization in translation can be used.

The inner ring 3 is typically mounted tightly around the shaft 1. The sleeve 12 is typically mounted tightly around the shaft 1.

The outer ring 4 is formed of two half-rings; a first half-ring 4A and a second half-ring 4B.

The first half-ring 4A is mounted fixed in translation relative to the casing 2 in the axial direction.

The second half-ring 4B is mounted free translationally relative to the casing 2 in the axial direction.

In the embodiment shown, the second half-ring 4B is mounted to move in translation relative to the casing 2 in the axial direction; it is arranged in a housing delimited on the one hand by the first half-ring 4A, and secondly by a stop 21 of the housing 2. The axial dimension of the housing is greater than the axial dimension of the second half-ring 4B, this difference in axial dimension determining the possible movement of the second half-ring 4B relative to the casing 2 in the axial direction.

Thus, FIGS. 1 and 2 show a clearance S between the second half-ring 4B and the stop 21 of the casing in FIG. 1, and between the second half-ring 4B and the first half-ring 4A in FIG.

In the embodiment shown, the first half-ring 4A comprises a base 41A provided with an indexing element 42A, forming here a rib, adapted to cooperate with a complementary recess 22 of the casing 2 so as to immobilize the first half -bub 4A in translation in the axial direction relative to the housing 2.

The base 41A of the first half-ring 4A as shown bears against the abutment 21 of the casing 2, and thus defines the housing in which the second half-ring 4B is arranged, which is then disposed between the base 41A of the first half-ring 4A and bearing elements 6 of the bearing.

A pre-load member 7 is positioned so as to exert a thrust force on the second half-ring 4B tending to position it in abutment against the first half-ring 4A. In the embodiment shown, the pre-load member is mounted in abutment against the abutment 21 of the casing 2.

The pre-load member 7 is typically a spring or a washer.

In operation, the rotating machine is configured so that the axial loads acting on the bearing tend to move the second half-ring 4B towards the stop 21 of the casing 2, that is to say to move the second half 4B ring of the first half-ring 4A, and therefore to oppose the pushing force exerted by the pre-load member 7 on the second half-ring 4B.

The pre-load member 7 defines a threshold value of axial force, such that:

- When the axial force is less than this threshold value, the second half-ring 4B remains in abutment against the first half-ring 4A, as shown in Figure 1. The bearing then operates with three points of contact, and is in a potentially unstable state due to its possible switchover in the second configuration described below.

- When the axial force is greater than this threshold value, the second half-ring 4B deviates from the first half-ring 4A and moves towards the stop 21 of the housing 2, until it comes into contact with this stop 21 of the housing 2 as shown in Figure 2. The bearing then operates with two points of contact, and can withstand significant axial forces.

The axial force applied to the bearing thus causes a sliding of the shaft 1 relative to the housing 2, marked by the clearance S in the figures, which can reach several millimeters, for example 2 mm or 1 mm. The displacement of the shaft 2 is indicated by an arrow F in FIG.

When the axial force decreases or changes direction, the second half-ring 4B returns in abutment against the first half-ring 4A, and the bearing then resumes operation with three points of contact.

The first half-ring 4A and the set S are typically configured so that when the second half-ring bears against the stop 21 of the casing 2, that is to say that the bearing is in the configuration shown in FIG. 2 and operates with two contact points, the first half-ring 4A does not disturb this operation in two contact points of the bearing, for example by dimensioning the first half-ring 4A and / or the set S in such a way as to to make sure that in this configuration in two points of contact, the first half-ring 4A does not come into contact with the rolling elements 5.

Figures 3 and 4 show a particular embodiment of the invention, wherein the first half-ring 4A is formed by machining the housing 2. Figures 3 and 4 respectively take the configurations shown in Figures 1 and 2.

The first half-ring 4A is therefore integral with the casing 2, which is typically machined so as to obtain the desired dimensional tolerances. The second half-ring 4B is unchanged compared to the embodiment shown in Figures 1 and 2.

This particular embodiment simplifies assembly by reducing the number of parts; it is indeed no longer necessary to immobilize the first half-ring 4A relative to the casing 2 insofar as the first half-ring 4A is integrated in the casing 2. This embodiment is however more complex in terms of machining; its use can therefore be advantageous for certain applications.

The operation of this embodiment is identical to that presented with reference to Figures 1 and 2, and is not repeated here in detail.

The proposed bearing thus makes it possible to achieve by means of a single component a plurality of functions, namely a double axial abutment, a radial bearing for a rotating element, and to allow the shaft to slide relative to the casing up to several millimeters. for example for opening a nozzle for an active axial balancing system.

The proposed bearing can in particular be used on turbopumps of space machines, in that it makes it possible to achieve a saving in weight and bulk compared to a doublet of bearings, while performing equivalent functions.

Claims

claims

Bearing for rotating machine in an axial direction (ZZ), comprising an inner ring (3) mounted around a shaft (1) and an outer ring (4) mounted in a housing (2), between which are arranged rolling elements (5),

characterized in that the outer ring (4) comprises first and second half-rings (4A, 4B),

the first half-ring (4A) being fixed in translation in the axial direction relative to the casing (2),

the second half-ring (4B) being slidably mounted in a housing between the first half-ring (4A) on the one hand, and a stop (21) of the casing (2) on the other hand, the stop (21) of the housing (2) comprising a pre-load member (7) exerting a thrust force on the second half-ring (4B) tending to position it in abutment against the first half-ring (4A).

2. Bearing according to claim 1, wherein the pre-load member (7) defines a threshold value of axial force so that when an axial force greater than this threshold value is exerted in opposition to the effort thrust exerted by the pre-load member (7), the second half-ring (4B) is no longer in axial abutment against the first half-ring (4A).

3. Bearing according to one of claims 1 or 2, wherein the first half-ring (4A) comprises a base (41A) provided with an indexing element (42A) so as to immobilize the first half-ring ( 4A) in translation in the axial direction (ZZ) relative to the housing (2), said base (41A) bearing against the stop (21) of the housing (2), the second half-ring (4B) being arranged between the base (41A) of the first half-ring (4A) and the rolling elements (5).

4. Bearing according to one of claims 1 or 2, wherein the first half-ring (4A) is formed by machining the housing.

5. Bearing according to one of claims 1 to 4, wherein the first half-ring (4A) and the stop (21) of the housing (2) define a maximum axial displacement (S) of the second half-ring (4B). ) less than 2mm.

Spacecraft turbo pump, comprising a bearing according to one of claims 1 to 5.