FR3125567A1 - Pivot for turbomachine mechanical reducer - Google Patents

Abstract

The invention relates to a pivot (14) with a longitudinal axis (Y), comprising: a longitudinal annular wall (16) having an outer surface which delimits the pivot on the outside and an inner surface which delimits an internal duct of the pivot, the internal duct being centered on the longitudinal axis (Y),an oil circuit (20) having a first part (20a) which extends in the internal duct and in fluid communication with a second part (20b ) which comprises a coiled conduit, the coiled conduit extending around the longitudinal axis (Y) being formed in the annular wall (16) between the inner surface and the outer surface of the pivot, the circuit (20) of oil comprises at least one oil inlet (22) at a longitudinal end of the pivot inner conduit (14) in fluid communication with the first portion (20a) and at least one oil outlet (24) in fluid communication with the second part (20b). Abstract Figure: Figure 6

Description

Pivot for turbomachine mechanical reducer

DOMAIN

The present invention relates to a pivot for a bearing and more particularly a pivot intended to be integrated into a reduction gear of a turbomachine such as a turbojet or a turboprop.

CONTEXT

The role of a mechanical reducer is to modify the speed and torque ratio between the input axis and the output axis of a mechanism.

New generations of dual-flow turbomachines, particularly those with a high bypass ratio, include a mechanical reduction gear to drive the shaft of a fan (also called a “fan”). Usually, the purpose of the reduction gear is to transform the so-called fast rotation speed of the shaft of a power turbine into a slower rotation speed for the shaft driving the fan.

Such a reducer comprises a central pinion, called sun gear, a crown and pinions called satellites, which are engaged between the sun gear and the crown. The satellites are held by a frame called the planet carrier. The solar, the crown and the planet carrier are planetary because their axes of revolution coincide with the longitudinal axis X of the turbomachine. The satellites each have a different axis of revolution Y, they are evenly distributed on a circle around the axis of the planets. These Y axes are parallel to the longitudinal X axis.

There are several reducer architectures. In the state of the art of turbofan engines, the reduction gears are of the planetary or planetary type. In other similar applications, there are so-called differential or “compound” architectures.

• On a planetary gearbox, the planet carrier is fixed and the crown constitutes the output shaft of the device which rotates in the opposite direction to the sun.
• On an epicyclic reducer, the crown is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the sun gear.
• On a differential gearbox, no element is fixed in rotation. The crown rotates in the opposite direction to the sun and the planet carrier.

Reducers can include one or more meshing stages. This meshing is ensured in different ways such as by contact, by friction or even by magnetic fields. There are several types of meshing by contact such as with straight or chevron teeth.

Conventionally, each satellite carried by the planet carrier is mounted to rotate freely on a pivot. The use of a pivot forming a plain bearing with a satellite pinion makes it possible to reduce bulk and mass and offers an almost infinite service life, provided that the bearing is constantly supplied with lubricating and cooling oil. It is also noted that a pivot can be used with a rolling bearing, an inner ring of which would be carried by the pivot, the outer ring then being integral in rotation with a satellite.

We know that the temperature of the pivots controls the bearing capacity of the bearing, whether it is of the hydrodynamic type or with rolling bearings. The more the temperature increases, the more the lift, that is to say the load capacity, of the pivot decreases. It is therefore understood that controlling the temperature of the pivot is of primary importance in order to be able to guarantee effective lift.

A longitudinal axis pivot is thus proposed for a bearing of a mechanical reduction gear, comprising:

• an annular wall which extends longitudinally by presenting, on the one hand, an outer surface which delimits the pivot on the outside and, on the other hand, an inner surface which delimits an internal duct of the pivot, the internal duct being centered on the longitudinal axis ,
• an oil circuit having a first portion that extends into the internal conduit and in fluid communication with a second portion that includes a coiled conduit, the coiled conduit extending about the longitudinal axis being formed in the annular wall between the inner surface and the outer surface of the pivot,
• the oil circuit comprises at least one oil inlet at a longitudinal end of the internal duct of the pivot in fluid communication with the first part and at least one oil outlet in fluid communication with the second part and which opens radially onto the outer surface of the annular wall.

This document also concerns a longitudinal axis pivot for a bearing of a mechanical reduction gear, comprising:

• an annular wall and stiffeners extending longitudinally and formed inside the annular wall,
• an oil circuit, a first part of which is delimited by an arrangement of stiffeners and communicates fluidly with a second part formed in the annular wall, the first part of the oil circuit comprising at least one oil inlet at a longitudinal end of the pivot and the second part comprising at least one oil outlet opening radially outside the annular wall.

According to the invention, the formation of an oil circuit in the pivot makes it possible to reduce the temperature thereof in operation in comparison with a pivot of the prior art. Thus, for a given load under given operating conditions, lowering the temperature of the pivot makes it possible to reduce the dimension of the pivot, thus allowing a gain in mass. When the pivot is used in a mechanical reducer, it is understood that the reduction of the mass of several pivots proves to be all the more advantageous. In addition, the mass of the pivot is also reduced due to the creation of an oil circuit.

The internal duct may include stiffeners formed inside the annular wall, the first part of the oil circuit being delimited by an arrangement of stiffeners.

According to the invention, a part of the oil circuit is delimited by stiffeners, which ensure both oil circulation and bearing of the load of the pivot in operation.

For this, the stiffeners may comprise first stiffeners extending longitudinally from a first radial wall of a first end of the pivot and interposed in a radial direction with second stiffeners extending longitudinally from a second radial wall of a second end of the fulcrum.

In other words, the stiffeners are interposed and arranged at a distance from each other in a radial direction so as to allow the passage of oil. The pivot will be oriented so that in operation the radial load taken up by the pivot can be oriented according to the direction of extension of the stiffeners. Formulated differently, the stiffeners will be oriented radially in operation, that is to say when the pivot will be, for example, integrated into a mechanical reduction gear arranged, for example, in a turbomachine.

The coiled conduit of the second part of the circuit may comprise at least a first annular portion fluidically independent of at least a second annular portion.

The coiled duct of the second part of the oil circuit may comprise at least one helical duct. An oil inlet in the coiled duct of the second part of the oil circuit can be formed at a middle part of the coiled duct.

The coiled duct of the second part of the oil circuit may have at least one annular serpentine portion around the longitudinal axis.

The invention also relates to a mechanical reduction gear for a gas turbine engine, comprising a ring gear and satellites engaged with the sun and with the crown and each mounted free to rotate around their axis on a planet carrier, the satellites each being able to rotate around of their axis via a pivot as described previously.

It also relates to a gas turbine engine for an aircraft comprising such a mechanical reduction gear whose solar surrounds and is integral in rotation with a shaft of the compressor of the turbine engine.

The turbomachine can also be such that the crown is integral with a casing or static annular shroud of the low pressure compressor.

The pivot according to this document can be used in a hydrodynamic plain bearing or else in a rolling bearing, for example ball or roller bearing.

The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of non-limiting example with reference to the appended drawings.

BRIEF DESCRIPTION OF FIGURES

• there is a schematic view in axial section of a turbomachine using the invention,
• there is a partial view in axial section of a mechanical reducer;
• there is a schematic view of a pivot according to the present invention and according to a section plane including the longitudinal axis Y of the pivot;
• there is a schematic sectional view of the pivot according to section plane II-II shown in ;
• there is another schematic view of the pivot according to the invention;
• there illustrates three variants of an oil circuit for a pivot according to the invention.

Claims (10)

Pivot (14) of longitudinal axis (Y) for a bearing of a mechanical turbine engine reduction gear, comprising:

• an annular wall (16) which extends longitudinally and has, on the one hand, an outer surface which delimits the pivot on the outside and, on the other hand, an inner surface which delimits an internal duct of the pivot, the internal duct being centered on the longitudinal axis (Y),
• an oil circuit (20) having a first portion (20a) which extends into the internal conduit and in fluid communication with a second portion (20b) which includes a coiled conduit, the coiled conduit extending around the longitudinal axis (Y) being formed in the annular wall (16) between the inner surface and the outer surface of the pivot,
• the oil circuit (20) comprises at least one oil inlet (22) at a longitudinal end of the internal conduit of the pivot (14) in fluid communication with the first part (20a) and at least one outlet (24) d oil in fluid communication with the second part (20b) and which emerges radially on the outer surface of the annular wall (16).

Pivot according to Claim 1, in which the internal duct comprises stiffeners (18) formed inside the annular wall (16), the first part (20a) of the oil circuit (20) being delimited by an arrangement of stiffeners. A pivot (14) according to claim 2, in which the stiffeners (18) comprise first stiffeners (18a) extending longitudinally from a first radial wall (26) of a first end of the pivot (14) and interposed in a direction (R) with second stiffeners (18b) extending longitudinally from a second radial wall (28) of a second end of the pivot (14). Pivot (14) according to one of Claims 1 to 3, in which the coiled duct comprises at least a first annular portion (P1) fluidically independent of at least a second annular portion (P2). A pivot (14) according to any preceding claim, wherein the coiled conduit comprises a helical conduit (34). Pivot (14) according to one of the preceding claims, in which the said coiled duct has at least one annular serpentine portion around the longitudinal axis. Pivot (14) according to one of the preceding claims, in which the said at least one oil outlet (24) from the second part (20b) of the oil circuit (20) opens into a longitudinal groove (32) of the radially outer surface of annular wall (16). Mechanical reduction gear for a gas turbine engine, comprising a ring gear and satellites (8) engaged with the sun gear (7) and with the ring gear (9) and each mounted free to rotate around their axis (Y) on a planet carrier ( 10), the satellites (8) each being able to rotate around their axis (Y) by means of a pivot (14) according to any one of the preceding claims. Gas turbine engine for aircraft comprising a reduction gear (6) according to the preceding claim, the sun gear (7) of which surrounds and is integral in rotation with a shaft of the compressor of the turbine engine. Turbomachine according to the preceding claim, in which the crown (9) is integral with a casing or annular stator shroud.