US-12624647-B2 - Turbomachine having an improved oil-recovery device

US12624647B2US 12624647 B2US12624647 B2US 12624647B2US-12624647-B2

Abstract

A turbomachine includes an oil-recovery device having, between mutually rotatable first and second members, a tubular tab of the first member surrounded by a tubular extension of a shroud of the second member. The tab defines, with a shroud of the first member, an interface zone. The tubular extension includes an outer groove opposite the tab, and the extension axially surrounds the tubular tab beyond an axial half-length of the tab. The extension has an inner diameter equal to an inner diameter of the outer shroud of the second member and has an outer diameter smaller than or equal to an outer diameter of the outer shroud. The second member has an annular groove with a rectangular cross-section.

Inventors

Vincent GOYON
Florence Irène Noëlle Leutard
Thomas Laurent Frederic GAUDUCHON
Antoine LURIN
Thierry Fachat
Michael OYHARCABAL
Kevin BOLZER

Assignees

SAFRAN AIRCRAFT ENGINES

Dates

Publication Date: 20260512
Application Date: 20230628
Priority Date: 20220630

Claims (10)

1 . A turbomachine comprising first and second internal members which are movable in rotation relative to each other about an axis X, and at least one guide bearing mounted between respective first and second tubular walls of axis X of the first and second members, the first member comprising a third wall transverse to the axis X, the second member comprising a fourth wall transverse to the axis X surrounded by said third wall, said third and fourth walls separating two enclosures, respectively, a first enclosure configured to lubricate the bearing, and a second enclosure, the fourth wall being bordered by an outer shell of the second member, and the third wall being bordered by an inner shell of the first member, the inner shell surrounding the outer shell and said inner and outer shells delimiting an interface area between said enclosures, said turbomachine further comprising an oil-recovery device comprising a tubular tab which extends the first tubular wall of the first member and which extends axially inside one end of the outer shell of the second member the tab being configured to conduct oil to be projected successively from the tab to the outer shell of the second member, and then from the outer shell of the second member to the third wall, said inner shell of the second member being extended by a tubular extension which surrounds the outside of the tubular tab axially beyond one end of the inner shell of the first member, and wherein is formed an outer concave groove facing away from the tubular tab, wherein the extension surrounds the outside of the tubular tab axially beyond an axial half-length of said tubular tab, has an inner diameter equal to an inner diameter of the outer shell of the second member and an outer diameter less than or equal to an outer diameter of the outer shell, and an annular groove of the second member is rectangular in cross-section.
2 . The turbomachine according to claim 1 , wherein the tubular extension comprises successively, starting from the outer shell of the second member: a first section, extending the outer shell of the second member, and having the same inner diameter and outer diameter as the inner diameter and outer diameter of said outer shell in the interface area, a second section, joined to the first section, with an inner diameter equal to the inner diameter of the outer shell in the interface area, and with an outer diameter smaller than the outer diameter of the outer shell in the interface area, and a third section, joined to the second section, with an inner diameter equal to the inner diameter of the outer shell, and with a specific outer diameter equal to the outer diameter of the outer shell, the annular groove being delimited by an external wall of axis X of the second section and by transverse walls of the first and third sections at their junction with the second section.
3 . The turbomachine according to claim 2 , wherein the first lubrication enclosure contains lubricating oil, and the external wall of axis X of the second section determines a width L of the groove, in that the transverse wall of the third section determines a height H of the groove, and the groove is such that the height H is an affine function by intervals of its width L, according to a relationship H=m×L+p whose coefficients m and p are associated with given characteristics of the lubricating oil.
4 . The turbomachine according to claim 3 , wherein characteristics of the lubricating oil comprise an operating temperature of less than 120° C., a viscosity of between 20 and 30 centistokes at 40° C. and 4.9 to 5 centistokes at 100° C. with a density of between 0.9 and 1.05 Kg/L.
5 . The turbomachine according to claim 4 , wherein: for an interval of width L greater than or equal to 4 mm and less than 6 mm, m=−0.6 and p=7, for an interval of width L of 6 to 7 mm, m=−0.2 and p=4.6, and for a width L greater than 7 mm, m=0 and p=3.2.
6 . The turbomachine according to claim 4 , wherein the first and second sections on the one hand, and the second and third sections on the other hand, are connected at the bottom of the groove by a radius of curvature R less than or equal to 0.6 mm.
7 . The turbomachine according to claim 4 , wherein the third section has an axial thickness greater than or equal to 1.2 mm.
8 . The turbomachine according to claim 1 , wherein the first member is an inter-turbine casing, in that the second member is a bearing support secured to a low-pressure shaft, the first bearing lubrication enclosure communicating with an oil-recovery duct connected to an oil circuit of the turbomachine, and the second enclosure is a pressurized enclosure communicating with an oil drainage duct connected to the outside of the turbomachine.
9 . The turbomachine according to claim 8 , wherein the interface area is an area for receiving configured to receive a system for flushing oil comprising a front spin and front lunulae and a rear spin and rear lunulae interposed between the inner and outer shells.
10 . The turbomachine according to claim 8 , wherein the interface area is an area for receiving a sealing system comprising at least one dynamic seal.

Description

TECHNICAL FIELD OF THE INVENTION The invention concerns a turbomachine equipped with an oil-recovery device with improved efficiency. TECHNICAL BACKGROUND The prior art comprises the documents WO 2014/199083 A1, EP 2 090 764 A1, EP 3 462 000 A1 and FR 3 075 866 A1. In a turbomachine of known type, a rear portion of the low-pressure turbine shaft is rotatably mounted, generally by at least one bearing mounted on a tubular wall of the inter-turbine casing. This bearing is placed in a first enclosure referred to as lubrication enclosure, which is delimited, on the one hand, by the inter-turbine casing and, on the other hand, by a bearing support secured to the shaft of the low-pressure turbine shaft. The inter-turbine casing and the bearing support secured to the low-pressure shaft also separate this first enclosure from a second enclosure adjacent to it. The low-pressure shaft is also secured to a bearing support. The lubrication enclosure is connected to an oil circuit comprising an oil inlet duct, through which oil is pumped into the enclosure. It comprises an oil-recovery device comprising an oil return duct, through which the oil returns towards the oil circuit in order to be pumped again. As the inter-turbine casing is stationary and the bearing support secured to the low-pressure shaft rotates relative to the latter, the sealing of the enclosure between these two members is ensured at the level of an interface area separating the two enclosures. The bearing support comprises an outer shell which is rotatably mounted inside an inner shell of the inter-turbine casing, and these two shells define the interface area. This interface area may be fitted with an oil flushing system comprising at least one spin and lunula device. This system may be supplemented by a dynamic sealing system, comprising a rear labyrinth seal and/or a brush seal. Outside the lubrication enclosure, the second enclosure is pressurised. The pressurisation allows to apply a positive pressure across the interface area to prevent oil escaping from the lubrication enclosure. The pressurised enclosure also comprises a oil drainage device comprising a drainage duct communicating with the outside of the turbomachine. To ensure the return of the lubricating oil from the bearing towards the oil return duct, the oil must be guided from the bearing to a wall of the inter-turbine casing which communicates with an inlet of an oil return duct. To achieve this, the oil must bypass the interface area without penetrating it. For this reason, the oil-recovery device comprises a tubular tab, commonly referred to as a “dropper launcher”, which extends from the tubular wall supporting the bearing and which extends inside one end of the outer shell of the bearing support. This tab is configured to guide the bearing when it is mounted, so that the low-pressure shaft may be precisely positioned so as to avoid any contact between the shaft and the inter-turbine casing. This tab is also configured to conduct oil to be projected successively from the tab to the outer shell of the bearing support, then from the outer shell of the bearing support to the wall of the inter-turbine casing leading to the inlet of the oil return duct. To prevent oil from penetrating the interface area, the outer shell of the bearing support is extended by a tubular extension which extends axially around the tubular tab beyond one end of the inner shell of the inter-turbine casing, and wherein is formed an outer annular groove of circular cross-section and concavity facing away from the tubular tab. This groove is intended to prevent oil from spreading along the tubular extension and then to the outer shell of the bearing support in the interface area. In operation, this configuration allows the oil to bypass the interface area without entering it. However, it has been found that a problem arises when an aircraft equipped with such a turbomachine is parked on the ground and the turbomachine is shut down. In this case, the interface area is no longer subject to the pressurisation pressure of the second enclosure, and the turbomachine is tilted backwards by a few degrees more than in normal operation. It has been found that the oil tends to flow by gravity along the dropper launcher tab, bypass the end of the tubular extension and then by capillary action into the annular groove of circular cross-section and through the interface area, in particular by capillary action through the interface area, to finally enter the second enclosure. Under certain conditions, oil may then be evacuated out of this second enclosure by the oil drainage device and run onto the tarmac on which the aircraft is parked. Oil may even reach a hotter enclosure of the turbomachine and cause smoke to be released, which would be detrimental to the perception that users might have of the quality of the turbomachine. There is therefore a real need for a new configuration of the oil-recovery device that allows the oil to