FR3062440A1 - INTEGRAL FILTER TURBOMACHINE SMOOTH BEARING AND METHOD FOR PRODUCING THE SAME - Google Patents

Abstract

Damping bearing (100), in particular for a turbomachine, comprising two coaxial annular rings (102, 104) extending respectively inside and outside a damping ring (106), characterized in that The damping ring is alveolar and forms a vibratory filter having a compressive and / or flexural deformation capacity greater than that of the rings.

Description

Agent (s):

GEVERS & ORES Public limited company.

® SMOOTH BEARING IN TURBOMACHINE WITH INTEGRATED FILTER AND METHOD FOR PRODUCING THE SAME.

(5?) Damper plain bearing (100), in particular for a turbomachine, comprising two coaxial annular rings (102, 104) extending respectively inside and outside of a damper ring (106), characterized in that the damping ring is cellular and forms a vibratory filter having a capacity for deformation in compression and / or in bending greater than that of the rings.

FR 3 062 440 - A1

Smooth bearing of an integrated filter turbomachine and its production method

TECHNICAL AREA

The present invention relates to a plain bearing, in particular for a turbomachine, as well as to a method for producing such a bearing.

STATE OF THE ART

A turbomachine, such as a turbojet engine, used for propulsion of aircraft comprises auxiliary machines necessary for its operation. These are, for example, fluid pumps for actuating control, lubrication or fuel components as well as electric generators. These machines are mounted in mechanical engagement with a gearbox which is itself connected to an engine shaft by an appropriate mechanical connection. This gearbox is commonly known by its acronym, AGB (acronym for "Accessory Gear Box"), in the field. The gearbox is held in suspension on the motor housing by suspension devices comprising connecting rods connected to the yokes of the housing.

Figure 1 shows a device of this type. The connecting rod 10 comprises an intermediate body of generally elongated shape and connected at its longitudinal ends to connecting heads having orifices whose axes are in substantially parallel planes, the section plane of Figure 1 passing through the axis A of one of these orifices 12. This orifice 12 receives an externally cylindrical cage 14, which is held by crimping in the orifice 12. The internal surface of the cage 14 serves as a guide for a socket with a spherical external surface forming a ball joint 16 .

Each head 18 of the connecting rod is mounted between the ears 20, 22 of a female yoke 24, only part of the connecting rod 10 being visible in FIG. 1. The visible head 18 is held between the two ears 20, 22 by a screw 26 which passes through the latter and the ball joint 16. The screw 26 is itself immobilized by a nut 28.

The connecting rod 10 is immobilized axially in the direction of the screw 26 by the ball joint 16 which, as seen in the figure, is supported on each side against a bearing 30 inserted in the orifice of each ear 20,22. Thanks to this assembly with ball joint, the head 18 can pivot freely around the axis of the screw and around any axis perpendicular thereto within the limits of the stops defined by the environment. The movement is limited in particular as a function of the interval, formed on either side, between the connecting rod head 18 and the ears 20, 22 of the yoke 24.

During the life of the AGB, efforts, in particular of direction parallel to the axis of the connecting rod 10, generated by the vibrations of the engine, pass through the suspension device towards the AGB and the accessories which it support. These requests end up causing damage to the AGB or said accessories.

One solution to this problem is to equip this type of device with vibration damping means. The solution illustrated in FIG. 1 consists in mounting the screw 26 in the orifices of the ears 20, 22 of the yoke by means of shock absorbing bearings 30. The orifice of each ear receives a shock absorbing bearing 30 comprising internal annular rings 34 and external 36 between which extends an annular damper 38 made of elastomer.

However, this technology has drawbacks linked, in particular, to the temperature resistance and to liquid products (pollutants, solvents, kerosene, etc.) of the damper (degradation of the elastomer and variability in dynamic behavior). In fact, because of its elastomer construction, the use of the shock absorber is limited to applications where the ambient temperature is generally less than 200 ° C. In addition, the failure mechanisms of elastomers are poorly formalized, which implies a high frequency of replacement of the bearing for replacement as soon as the first crack appears when it should still be able to perform its function for many cycles.

FIG. 2 illustrates another solution to the aforementioned problem, which is described in patent FR-B1-2 866 683. The solution consists in attaching an elastomer damper 40 to the head 18 of the connecting rod 10. However, this damper has the same disadvantages as the previous solution.

STATEMENT OF THE INVENTION

The present invention provides an improvement to the technology described above, which represents a simple, effective and economical solution, in particular to respond to the aforementioned problem of thermal resistance of the damping means.

The invention provides a damping plain bearing, in particular for a turbomachine, comprising two coaxial annular rings extending respectively inside and outside of a damping ring, characterized in that the damping ring is cellular and forms a vibratory filter having a capacity for deformation in compression and / or in bending greater than that of the rings.

The bearing or part of the bearing can thus be made of a material resistant to high temperatures, for example greater than 200 ° C. This is made possible by the honeycomb structure having flexibility properties and in particular deformation capacities in compression and / or in bending sufficient to filter out a vibration spectrum to which a system suspended from this bearing is likely to be exposed in operation.

The compressive and / or bending deformations of the ring may be deformations with respect to the axis of revolution of the ring and / or of a radial axis to this axis of revolution

The bearing according to the invention may include one or more of the characteristics below, taken in isolation from each other or in combination with each other:

the bearing is at least partly metallic, the bearing is made in one piece, said ring has a lattice-like structure, the size and / or the concentration of the cells of said ring varies (s) around and / or along of an axis of revolution of said ring.

The present invention also relates to a suspension device, in particular for a turbomachine, comprising a yoke comprising at least one orifice in which is mounted a bearing according to one of the preceding claims.

The invention also relates to a turbomachine, in particular an aircraft, comprising such a bearing or such a device, in particular for the suspension of an AGB from an engine casing.

The invention finally relates to a process for producing a bearing, or part of a bearing, as described above, characterized in that it comprises a step of additive manufacturing of the bearing, and in particular of its part. alveolar ring, for example by selective fusion of powder beds.

DESCRIPTION OF THE FIGURES

The invention will be better understood and other details, characteristics and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the accompanying drawings in which:

FIG. 1 is a schematic sectional view of a particular model of connecting rod connected to a yoke, according to an art prior to the present invention,

FIG. 2 is a schematic sectional view of a connecting rod connected to a yoke, according to another art prior to the present invention,

FIG. 3 is a very schematic partial view of a bearing according to the invention,

- Figure 4 is, for example, a very schematic view of an installation for the additive manufacturing of bearing or part of a bearing, here according to Figure 3.

DETAILED DESCRIPTION

A smooth and damper bearing 100 according to the invention, as illustrated in FIG. 3, comprises two rings, internal 102 and external respectively

104, of the same axis A, and a ring 106 extending between these rings.

Each ring 102, 104 preferably comprises two smooth cylindrical surfaces, respectively internal and external. The ring 106 extends between the external cylindrical surface of the internal ring 102 and the internal cylindrical surface of the external ring 104.

The rings 102, 104 are preferably full (without cell) and metallic.

The ring 106 is here cellular and preferably metallic. It thus comprises cells configured to give the bearing 10 a vibratory filter function. The ring 106 has a capacity for deformation in compression and / or in bending greater than that of the rings 102, 104.

The ring 106 preferably includes a lattice-like structure formed by a three-dimensional set of patterns (such as crisscrossed bars) linked to each other. These patterns are separated and spaced from each other by spaces which form the cells of the ring 106. The geometry of this trellis allows the adaptation of the damping function.

The size and / or the concentration of the cells of the ring varies (s) around and / or along the axis A. This allows an optimization of the damping function according to preferred axes.

Advantageously, the rings 102, 104 and the ring 106 are formed in one piece. The bearing is thus of the monobloc type.

This type of bearing can be used in the environment as described with reference to FIG. 1, in place of the assembly constituted by the rings 34, 36 and the shock absorber 38.

The bearing 100 is advantageously produced by additive manufacturing. FIG. 4 shows an example of an installation for producing a bearing by additive manufacturing, and in particular by selective melting of powder beds via a high energy beam.

The machine comprises a supply container 170 containing powder of a material such as a metal alloy, a roller 130 for transferring this powder from this container 170 and spreading a first layer 110 of this powder on a construction support 180 .

The machine also includes a recycling bin 140 for recovering the used powder (in particular non-melted or unsintered) and the excess powder (for the most part), after spreading the layer of powder on the construction support 180. Thus, most of the powder in the recycling bin is made up of new powder. Also, this recycling bin 140 is commonly called by the profession overflow bin or ashtray.

This machine also includes a generator 190 of an energy beam (for example laser) 195, and a control system 150 capable of directing this beam 195 onto any region of the construction support 180 so as to scan any region of 'a layer of powder. The shaping of the energy beam (laser) and the variation of its diameter on the focal plane are done respectively by means of a beam dilator 152 and a focusing system 154, the assembly constituting the optical system.

This machine for applying the process similar to a direct metal deposition process or DMD (acronym for English Direct Métal Déposition) on a powder can use any high energy beam in place of the laser beam 195, as long as this the beam is sufficiently energetic to in the first case melt or in the other case to form necks or bridges between the powder particles and part of the material on which the particles rest.

The roller 130 can be replaced by another suitable depositing system, such as a reel (or hopper) associated with a scraper blade, a knife or a brush, capable of transferring and spreading the powder in a layer.

The piloting system 150 comprises for example at least one orientable mirror 155 on which the laser beam 195 is reflected before reaching a layer of powder, each point of the surface of which is always located at the same height relative to the lens. focusing, contained in the focusing system 154, the angular position of this mirror 155 being controlled by a galvanometric head so that the laser beam scans at least one region of the first layer of powder, and thus follows a pre-established part profile .

This machine works as follows. Using the roller 130, a first layer 110 of powder of a material is deposited on the construction support 180, this powder being transferred from a feed tank 170 during a forward movement of the roller 130 and then it is scraped , and possibly slightly compacted, during one (or more) movement (s) of return of the roller 130. The excess powder is recovered in the recycling tank 140. A region of this first layer 110 of powder is carried , by scanning with the laser beam 195, at a temperature higher than the melting temperature of this powder (liquidus temperature). The galvanometric head is ordered according to the information contained in the database of the computer tool used for the computer-aided design and manufacture of the part to be manufactured. Thus, the powder particles 160 of this region of the first layer 110 are melted and form a first bead 115 in one piece, integral with the construction support 180. At this stage, it is also possible to scan with the laser beam several regions independent of this first layer to form, after fusion and solidification of the material, several first strands 115 disjoint from each other. The support 180 is lowered by a height corresponding to the already defined thickness of the first layer (between 20 and 100 μm and in general from 30 to 50 μm). The thickness of the powder layer to be merged or consolidated remains a variable value from one layer to another because it is highly dependent on the porosity of the powder bed and its flatness while the pre-programmed displacement of the support 180 is an invariable value to the nearest game. A second layer 120 of powder is then deposited on the first layer 110 and on this first bead 115, then a region of the second layer 120 which is partially or completely above this first bead is heated by exposure to the laser beam 195 115, so that the powder particles of this region of the second layer 120 are melted, with at least part of the first bead 115, and form a second bead in one piece or consolidated 125, all of these two cords 115 and 125 forming a block in one piece. To this end, the second bead 125 is advantageously already fully linked as soon as a part of this second bead 125 binds to the first element 115. It is understood that according to the profile of the part to be constructed, and in particular in the case of undercut, the aforementioned region of the first layer 110 may not be, even partially, below the aforementioned region of the second layer 120, so that in this case the first codon 115 and the second cord 125 then do not form a single block. This process of building the part is then continued layer by layer by adding additional layers of powder to the assembly already formed. The scanning with the beam 195 makes it possible to construct each layer by giving it a shape in accordance with the geometry of the part to be produced, for example the aforementioned trellis structures. The lower layers of the room cool more or less quickly as the upper layers of the room are built.

In order to reduce contamination of the part, for example dissolved oxygen, oxide (s) or another pollutant during its layer-by-layer manufacture as described above, this manufacture must be carried out in an enclosure at degree d '' hygrometry controlled and adapted to the process / material couple, filled with a neutral gas (non-reactive) with respect to the material considered such as nitrogen (N2), argon (Ar) or helium (He ) with or without the addition of a small amount of hydrogen (H2) known for its reducing power. A mixture of at least two of these gases can also be considered. To prevent contamination, in particular by oxygen from the surrounding environment, it is customary to put this enclosure under overpressure.

Thus, selective melting or selective sintering by laser makes it possible to construct, with good dimensional accuracy, slightly polluted parts whose geometry in three dimensions can be complex.

Selective melting or selective sintering by laser also preferably uses powders of spherical morphology, clean (that is to say not contaminated with residual elements from the synthesis), very fine (the size of each particle is between 1 and 100 pm and preferably between 45 and 90 pm), which makes it possible to obtain an excellent surface condition of the finished part.

Selective melting or selective sintering by laser also allows a reduction in manufacturing times, costs and fixed costs, compared to a part molded, injected or machined in the mass.

The invention allows the following gains and opportunities:

- reduced mass,

- increased reliability,

- reduction of maintenance load and stocks,

- increased operating temperature range and adaptable as needed by variation of metallic material (possible for submarine, terrestrial, aeronautical and space use),

- reduction of manufacturing steps and required components,

- better consistency of the flexibility parameter during manufacturing,

- possible orientation of the damping function by the distribution of mesh geometry, including in rotary mode, and

- maintenance of electrical continuity between the structures connected by the bearing when the bearing is metallic.

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Claims (8)

1. Damper plain bearing (100), in particular for a turbomachine, comprising two coaxial annular rings (102, 104) extending respectively inside and outside of a damper ring (106), characterized in that that the damping ring is cellular and forms a vibratory filter having a capacity of deformation in compression and / or in bending greater than that of the rings. 2. A bearing (100) according to claim 1, in which it is at least partly metallic. 3. Bearing (100) according to claim 1 or 2, wherein it is made in one piece. 4. Bearing (100) according to one of the preceding claims, wherein said ring (106) has a lattice-like structure. 5. Bearing (100) according to one of the preceding claims, in which the size and / or the concentration of the cells of said ring varies (s) around and / or along an axis of revolution of said ring. 6. Suspension device, in particular for a turbomachine, comprising a yoke (24) comprising at least one orifice in which a bearing is mounted according to one of the preceding claims. 7. A turbomachine, in particular an aircraft, comprising a bearing or a device according to one of the preceding claims, in particular for the suspension of an AGB from an engine casing. 8. Method for producing a bearing, or part of a bearing, according to one of claims 1 to 5, characterized in that it comprises a step of additive manufacturing of the bearing (100), and in particular of its ring (106), for example by selective fusion of powder beds. 1/2 2/2