Rotating assembly comprising a transmission member and an oil distribution system

A rotary assembly comprising a transmission member and an oil distribution system enabling oil to be supplied to the transmission member in order to lubricate it. According to the invention, the oil distribution system comprises at least one oil transfer chamber provided with at least one feed orifice configured to receive oil from outside the rotary assembly; the transmission member includes at least one rotary portion provided with at least one oil reception chamber; at least one link duct provides fluid flow connection between the oil transfer chamber and the oil reception chamber; the oil distribution system is driven by said rotary portion of the transmission member to rotate together with it; and the rotary assembly is configured in such a manner as to accommodate a given amount of axial and/or radial relative movement between said rotary portion of the transmission member and the oil distribution system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national phase entry under 35 U.S.C. §371 of International PCT Application No. PCT/FR2014/052183, filed on Sep. 4, 2014, which claims priority to French Patent Application No. FR 1358581, filed on Sep. 6, 2013, the entireties of each of which are incorporated by reference herein.

FIELD OF THE INVENTION

The present description relates to a rotary assembly comprising a transmission member and an oil distribution system serving to supply oil to the transmission member in order to lubricate it.

Such a rotary assembly may be used in particular in the field of aviation, within airplane turbojets or within helicopter turboshaft engines, to mention only these examples.

STATE OF THE PRIOR ART

The turbojets that are conventionally to be found these days in the field of civil aviation are bypass turbojets with two spools. Nevertheless, because of ever-increasing constraints on operating costs, closely associated with the cost of fuel, which nowadays is very high, new turbojet projects have been proposed that benefit from lower specific consumption.

One promising option consists in fitting a turbojet with a speed-reducing gearbox interposed between the low pressure compressor and the fan: in this way, it is possible to increase the speed of rotation of the low pressure spool, thereby increasing the overall efficiency of the turbojet, while reducing the speed of the fan, thereby reducing aerodynamic disturbances at the blade tips and thus contributing to reducing the noise generated by the fan.

A turbojet with a gearbox thus presents important qualities, but at present certain difficulties still remain that need to be overcome before launching industrial production.

In particular, the gearbox needs to be lubricated and cooled in order to ensure that it operates correctly without being damaged. In a conventional gearbox, these functions are traditionally provided by a flow of oil fed centrifugally; nevertheless, it has been found that the pressure of the oil is not sufficient in such configurations of gearbox turbojets to ensure that centrifugal feeding is effective.

Another solution that has been proposed consists in transferring oil between the casing and the gearbox via an oil transfer bearing mounted on the gearbox. Nevertheless, that solution is not satisfactory either since the operation of the oil transfer bearing is greatly disturbed by the erratic movements and changes in axis of the gearbox caused by the large amount of vibration to which it is subjected: in particular, it is found that the oil transfer bearing is the seat of premature wear thereby affecting the feed of oil and thus the lifetime of the gearbox.

There thus exists a real need for a rotary assembly comprising a transmission member and an oil distribution system and that is free, at least in part, of the drawbacks inherent to the above-specified known configurations.

SUMMARY OF THE INVENTION

The present description relates to a rotary assembly comprising a transmission member and an oil distribution system, wherein the oil distribution system comprises at least one oil transfer chamber provided with at least one feed orifice configured to receive oil from outside the rotary assembly; the transmission member includes at least one rotary portion provided with at least one oil reception chamber; at least one link duct provides fluid flow connection between the oil transfer chamber and the oil reception chamber; the oil distribution system is driven by said rotary portion of the transmission member to rotate together with it; and the rotary assembly is configured in such a manner as to accommodate a given amount of axial and/or radial relative movement between said rotary portion of the transmission member and the oil distribution system.

In the present description, the term the oil distribution system is driven by said rotary portion of the transmission member to rotate together with it is used typically to mean that the oil distribution system rotates at substantially the same speed, and in any event with the same speed on average as the rotary portion of the transmission member with a phase shift that remains substantially zero, and that is in any event zero on average, such that any given point of the oil distribution system is always substantially facing the same zone of the rotary portion of the transmission member. This definition thus accommodates small transient differences in speed or small transient phase shifts due to parasitic vibration, or in the event of the rotary portion of the transmission member accelerating or decelerating, for example.

In addition, the term “given amount of axial and/or radial relative movement” is used to mean a relative movement of amplitude that exceeds that which results from ordinary assembly clearances: the idea is to provide freedom of movement that is greater than such conventional clearances.

Under such circumstances, the orifice of the oil reception chamber is always substantially facing the same orifice of the oil transfer chamber, thereby enabling the link duct to be put into place and thus enabling oil to be distributed from the oil distribution system to the rotary portion of the transmission member.

Furthermore, by means of this configuration, and excluding the rotary drive, movements of the transmission member and of the oil distribution system are decoupled, at least over a given amplitude range: the rotary portion of the transmission member can thus be subjected to certain erratic movements or changes of axis caused by the vibration of the transmission member, with propagation thereof to the oil distribution system being reduced or even completely avoided. The position and the alignment of the oil distribution system relative to outside the rotary assembly is therefore disturbed little or not at all during its rotation, thereby ensuring that the oil distribution system is fed directly from the outside while reducing leaks of oil at this interface.

In particular, this limits any risk of the erratic movements of the transmission member causing the oil distribution system to come into collision with or to rub against certain members that are external to the rotary assembly, e.g. a casing: under such circumstances, the efficiency of the rotary assembly is preserved and it suffers little wear, thereby prolonging its lifetime.

In the present description, the terms “axial”, “radial”, “tangential”, “inner”, and “outer”, and their derivatives are defined relative to the main axis of the rotary assembly.

In certain embodiments, the oil distribution system is configured to be held radially in a casing, and the transmission member is floatingly mounted in the casing, the assembly being configured in such a manner that the oil distribution system substantially conserves its alignment in the casing regardless of the axial and/or radial movements of the transmission member. The term “alignment” is used to cover both the direction and the position of its main axis. The oil distribution system is thus centered relative to the casing and not relative to the transmission member: since the parasitic axial and/or radial movements of the transmission member are decoupled from the rotary movement of the oil distribution system, the oil distribution system can remain in alignment with the portion of the casing in which it is held. With the exception of its rotary motion, the position and the orientation of the interface between the oil distribution system and the casing is thus stable over time, thereby ensuring reliability of the oil feed and durability of the oil distribution system.

In certain embodiments, the link duct is floatingly mounted between firstly contact surfaces of the oil distribution system and secondly contact surfaces of the rotary portion of the transmission member. This floating mounting enables the link duct to follow the small parasitic movements, if any, of the rotary portion of the transmission member without any loss of alignment of the link duct disturbing the alignment of the oil distribution system.

In certain embodiments, an O-ring is interposed between the link duct and said contact surfaces of the oil distribution system.

In certain embodiments, an O-ring is interposed between the link duct and said contact surfaces of the rotary portion of the transmission member. These O-rings enable damping and compensation of the relative movements between the rotary portion of the transmission member and the oil distribution system to be improved. They also serve to provide sealing between the link duct and said contact surfaces.

In certain embodiments, the oil distribution system is connected to the rotary portion of the transmission member via at least one rotary drive device including a damper. The rotary drive device provided with the damper serves to drive the oil distribution system in rotation, while limiting transmission of parasitic movements from the transmission member to the oil distribution system.

In certain embodiments, the oil distribution system is connected to the rotary portion of the transmission member via a plurality of rotary drive devices that are regularly arranged around the axis of the oil distribution system. In this way, the various rotary drive devices can co-operate in taking up equally the small parasitic variations in the axis of the rotary portion of the transmission member without transmitting them to the oil distribution system. Preferably, the rotary assembly has five rotary drive devices of this type.

In certain embodiments, the rotary drive device comprises a drive protrusion integral with or secured to the wall of one of the two elements constituted by the rotary portion of the transmission member and the oil distribution system, said protrusion being engaged in a drive opening in a wall of the other one of said elements, and a damper is interposed between said drive protrusion and said drive opening.

In certain embodiments, the drive protrusion is a screw fastened in said wall of said element.

In certain embodiments, the drive protrusion is carried by a wall of the rotary portion of the transmission member and the drive opening is formed in a wall of the oil distribution system.

In certain embodiments, the damper may deform both axially and radially.

In certain embodiments, the damper comprises an inner ring in contact with the drive protrusion, an outer ring mounted in said drive opening, and an intermediate body that is axially and radially flexible. This configuration thus serves to accommodate parasitic movements of the rotary portion of the transmission member in all directions. It also constitutes a system that is static, the relative movements being compensated by the elasticity of the damper.

In certain embodiments, the damper possesses axial symmetry.

In certain embodiments, the flexible intermediate body is made of an elastomer material, in particular out of nitrile rubber or of silicone.

In certain embodiments, the flexible intermediate body is adhesively bonded to the inner and outer rings.

In certain embodiments, the inner ring and/or the outer ring are made of metal.

In certain embodiments, the outer ring is an interference fit in the drive opening.

In other embodiments, the rotary drive device comprises a drive protrusion integral with or secured to a wall of one of the two elements constituted by the rotary portion of the transmission member and the oil distribution system, and a spacer provided around the drive protrusion, said spacer being engaged in a drive opening in a wall of the other one of said elements; a damper is provided between said drive protrusion and the spacer. The spacer serves to define accurate clearances relative to the drive opening so as to accurately adjust the axial and/or radial relative movements that are authorized between the rotary portion of the transmission member and the oil distribution system.

In certain embodiments, the damper may be an O-ring.

In certain embodiments, the drive protrusion is carried by a wall of the rotary portion of the transmission member and the drive opening is formed in a drive lug of the oil distribution system.

In certain embodiments, the rotary drive device is configured to accommodate a given axial movement of the spacer.

In certain embodiments, the rotary drive device is configured to leave axial clearance less than 1 millimeter (mm), preferably less than 0.5 mm, more preferably equal to about 0.2 mm, between the front face of the spacer and the surface of the rotary portion.

In certain embodiments, the spacer also includes a flange extending behind the drive opening, the diameter of the flange being greater than the width of the drive opening; the rotary drive device is configured so as to leave axial clearance of less than 5 mm, preferably less than 2 mm, more preferably equal to about 1 mm between the flange of the spacer and the rear face of the drive lug of the oil distribution system.

In certain embodiments, the drive device is configured so as to leave radial clearance of less than 1 mm, preferably less than 0.6 mm, more preferably equal to about 0.4 mm between the spacer and the drive protrusion.

In certain embodiments, the drive opening is an oblong opening having sides including respective rectilinear portions; the spacer has flats configured to co-operate with the rectilinear portions of the drive opening, the spacer being capable of moving axially and radially within the drive opening.

In certain embodiments, the drive device is configured to leave lateral clearance of less than 0.5 mm, preferably less than 0.2 mm, more preferably equal to about 0.12 mm between the flats of the spacer and the rectilinear portions of the drive opening.

In certain embodiments, the spacer may move within the drive opening over a length greater than 0.2 mm, preferably equal to about 0.5 mm.

In certain embodiments, the oil transfer chamber is annular and continuous over 360°.

In other embodiments, the oil transfer chamber of the oil distribution system extends over an angular sector that is strictly less than 360°. In this way, the oil transfer chamber is not continuous over a complete turn of the oil distribution system, thereby preventing oil from turning within the oil transfer system and thus limiting the impact of oil movements on the dynamic behavior of the oil distribution system as a whole. This serves to ensure that the oil remains in the same reference frame as the distribution system.

In certain embodiments, the transmission member is a speed-reduction gearbox.

In certain embodiments, the transmission member is an epicyclic gear train.

In certain embodiments, said rotary portion of the transmission member is a planet carrier.

In certain embodiments, said planet carrier possesses a plurality of spindles each carrying a planet gear, each spindle being provided with an oil reception chamber configured to lubricate the bearing of said planet carrier, and each oil reception chamber being in fluid flow connection with the oil transfer chamber of the oil distribution system via a respective link duct.

The present description also relates to a turbine engine including a rotary assembly in accordance with any of the above-described embodiments, the oil distribution system of the assembly being housed in a casing provided with an oil feed chamber.

In certain embodiments, the casing includes an annular oil outlet cavity that is open over 360° towards the oil distribution system and that is in fluid flow connection with the oil feed chamber; the oil distribution system includes an annular oil inlet cavity open over 360° facing the oil outlet cavity of the casing and in fluid flow connection with the oil transfer chamber via said at least one feed orifice. By means of this rotary assembly in which the oil distribution system remains in alignment within the casing in spite of parasitic movements of the transmission member, the annular oil inlet and outlet cavities remain in alignment facing each other in the same plane in spite of the oil distribution system rotating and in spite of the parasitic movements of the transmission member: the feed of oil to the rotary oil distribution system from the stationary casing can thus be achieved in reliable manner. Leaks of oil at the interface are also limited.

In certain embodiments, the oil inlet cavity of the oil distribution system is boxed in on either side by a sealing segment.

In other embodiments, leaks of oil at the interface between the oil distribution system and the casing maintain a film of oil. The sealing segments are dimensioned in such a manner as to ensure that the pressure of the oil enables the oil to go beyond the sealing segments in order to initiate the oil film. The oil film serves to lubricate the interface between the oil distribution system and the casing so as to ensure it rotates properly. The casing surrounding the distribution system and the transmission member preferably forms a closed enclosure enabling the oil to be recovered and preventing it from polluting or being polluted by other elements of the turbine engine.

The above-mentioned characteristics and advantages, and others, appear on reading the following detailed description of embodiments of the proposed rotary assembly. This detailed description makes reference to the accompanying drawings.

DETAILED DESCRIPTION OF EMBODIMENTS

In order to make the invention more concrete, examples of rotary assemblies are described in detail below with reference to the accompanying drawings. It should be recalled that the invention is not limited to these embodiments.

FIG. 1is a section view of a bypass turbojet1with a gearbox of the invention shown in a vertical plane containing its main axis A. Going from upstream to downstream, the jet comprises a fan2, a gearbox3, a low pressure compressor4, a high pressure compressor5, a combustion chamber6, a high pressure turbine7, and a low pressure turbine8.

In such a turbojet1with a gearbox, the high pressure turbine7drives the high pressure compressor5via a high pressure shaft9. The low pressure turbine8, also referred to as a fast turbine, drives the low pressure compressor4, also referred to as a fast compressor, via low pressure shaft10. The fast turbine8also drives the fan2via the speed-reduction gearbox3. In this way, the fan2may be driven at a slow speed, which is favorable from an aerodynamic point of view, while the low pressure compressor4may be driven at a faster speed, which is favorable from a thermodynamic point of view.

The gearbox3is shown in part inFIG. 2: it comprises an epicyclic gear train having an outer ring31, a sun gear32, and planet gears33. The planet gears33are mounted to rotate on spindles34of a planet carrier35. The bearings36between the planet gears33and their respective spindles34may be smooth as in this example, or they may include rolling mechanisms, e.g. having rollers. In this example, the planet carrier35drives the fan2while the sun gear is driven by the low pressure shaft10.

The gearbox3is floatingly mounted in a casing40: in particular because of the vibration to which the gearbox3is subjected, it can move within the casing40by several millimeters axially or radially relative to its nominal position. Because of these parasitic movements, the axis of the gearbox3may likewise depart by several degrees from its nominal alignment axis in the casing40.

In order to limit the friction of the planet gears33on their spindles34, the bearings36need to be lubricated: oil lubrication is therefore provided. This flow of oil also serves to cool the bearings36. In order to enable this lubrication, the spindles34of the planet gears33include respective oil reception chambers37in fluid flow connection with the bearing36via channels (not shown) passing through the spindle34. The casing40has an oil feed chamber41. Oil is transferred from the oil feed chamber41of the casing40to the various oil reception chambers37of the spindles34of the planet carriers35by means of an oil distribution system50.

This oil distribution system50, which can be seen more clearly inFIGS. 3A, 3B, and 4, is a generally annular part having a cylindrical outer wall51and an oil transfer chamber52extending in a circular arc inside and along practically all of the outer wall51. In this embodiment, the epicyclic gear train has five planet gears33: it is therefore advantageous for the oil transfer chamber to extend over a little more than four-fifths of a complete turn in order to be capable of feeding the five spindles34of the planet carriers35.

The oil distribution system50is mounted in the casing40by engaging its cylindrical outer wall51in a cylindrical band42of the casing40.

In order to transfer oil from the oil feed chamber41to the oil transfer chamber52, the casing40includes, on the back of the band42, an annular oil outlet cavity43extending over 360° along the band42and in fluid flow connection with the oil feed chamber41via an orifice44.

The oil distribution system50has an annular oil inlet cavity53that is open over 360° in the cylindrical outer wall51and that is in fluid flow connection with the oil transfer chamber52via feed orifices54.

These annular oil outlet and inlet cavities43and53are arranged in such a manner as to face each other when the oil distribution system50is mounted in the casing40, the band42being provided with through orifices45in the oil outlet cavity43. In this example, the band42is provided with at least ten through orifices45. The oil distribution system50also has two annular sealing gaskets55arranged in annular grooves66formed in the cylindrical outer wall51on either side of the annular oil inlet cavity53. The sealing gaskets55are dimensioned in such a manner that a small oil leakage flow rate remains possible so as to maintain a film of oil at the interface between the oil distribution system and the casing40. The casing surrounding the distribution system and the transmission member form a closed enclosure enabling oil to be recovered and preventing oil from polluting or being polluted by other elements of the turbine engine.

In order to transfer oil from the transfer chamber52to the oil reception chambers37of the spindles34, the front wall57of the oil distribution system50has reinforcement58provided at the locations facing the spindles34of the planet carrier35: in this example, the oil distribution system50thus has reinforcement58in five regularly spaced-apart locations. The reinforcement58in each location is in fluid flow communication with the oil transfer chamber52via orifices59.

Each spindle34of the planet carrier35has reinforcement38in fluid flow communication with the oil reception chamber37.

For each spindle34, a link duct70is floatingly mounted firstly between the side walls of the reinforcement38of the spindle34, and secondly between the side walls of the reinforcement58of the facing oil distribution system50, thereby enabling the oil reception chamber37of the spindle34to be in fluid flow connection with the oil distribution chamber52. The link duct70also has front and rear O-rings71and72providing sealing between the link duct70and the respective side walls of the reinforcement38and58. The O-rings also provide a certain amount of damping and create annular linear connections for absorbing radial and angular dispersions between the oil distribution system and the oil reception chamber.

Thus, while feeding oil, oil leaves the oil feed chamber41of the casing40in order to fill the annular outlet cavity43via the orifice44; oil then pours into the entire annular outlet cavity43and passes through the passages45in the band in order to fill in turn the inlet cavity53of the oil distribution system50, and then enter into the oil transfer chamber52via the admission orifices54; the oil can then be distributed via the link ducts70to the oil reception chambers37of the spindles34from which it is conveyed to the bearings36.

In order to enable the oil distribution system50to rotate together with the planet carriers35of the gearbox3while limiting stresses exerted on the link duct70, the rotary assembly constituted by the gearbox3and its oil distribution system50further includes a rotary drive device80. As in the present example, the rotary assembly preferably has as many rotary drive devices80as there are spindles34, each rotary drive device80being located in the proximity of a link duct70.

More precisely, the oil distribution system50has drive lugs60extending radially outwards from the front wall57of the oil distribution system50in register with the reinforcement58. Each drive lug60is pierced by a circular drive opening61in which the rotary drive device80is engaged.

In this example, the rotary drive devices80are situated in the proximity of the link ducts70and on the same diameters as the link ducts. Nevertheless, depending on the case of the oil distribution system, other configurations are possible. In particular, it could equally well be advantageous for each rotary drive device to be located between two planets. They could also be closer to the center of the oil distribution system in order to reduce the overall size of the system.

The rotary drive device80includes a damper81comprising an outer metal ring82, an inner metal ring83, and a flexible intermediate body84made of silicone that is adhesively bonded between the outer and inner rings82and83. The damper81is an interference fit within the drive opening61via its outer ring82. The inner ring83has a radially-extending flange85on its front face. A drive screw86is engaged within the inner ring83and is fastened in the planet carrier35in such a manner as to press the radial flange85of the inner ring83against the surface of the planet carrier35.

By means of this rotary drive device80, rotation of the planet carrier35drives the oil distribution system50in rotation. Nevertheless, the axial and radial movements of the gearbox3are damped by means of the flexible intermediate body84of the damper81and are therefore not transmitted to the oil distribution system50: except for its movement in rotation, the position of the oil distribution system50relative to the casing40is therefore unchanging. In addition, because of the plurality of rotary drive devices80that are distributed around the oil distribution system50, losses of alignment of the gearbox3are likewise not transmitted to the oil distribution system50.

FIGS. 5, 6A, and 6Bshow a second embodiment of the oil distribution system150that is entirely analogous to the first embodiment but that is fitted with a rotary drive device180that is different.

In this embodiment, the oil distribution system150likewise has drive lugs160, each drive lug160being pierced by a drive opening161; nevertheless, in this embodiment the drive opening161is not circular but is oblong, each of its sides including a rectilinear portion162.

The drive device180includes a spacer187with side flats188that are configured to co-operate with the rectilinear portions162of the drive orifice161, and a rear radial flange189that is configured to co-operate with the rear surface of the drive lug160.

The spacer187also has a central bore190in which there is engaged a drive screw186that is fastened in the planet carrier135. An O-ring191, acting as a damper, is also arranged between the drive screw186and the bore190in the spacer187.

This rotary drive device180is configured so as to leave a certain amount of clearance between the various parts. Thus, as shown inFIG. 6B, when the radial flange189of the spacer187is pressed against the shoulder186aof the drive screw186and when the drive lug160is pressed against the planet carrier135, first clearance J1of about 0.2 mm is left between the front face of the spacer187and the surface of the planet carrier135; furthermore second clearance J2of about 1 mm is left between the radial flange189of the spacer187and the rear surface of the drive lug160.

As shown inFIG. 6A, third clearance J3of about 0.4 mm is left between the drive screw186and the central bore190of the spacer187; this third clearance J3is filled in by the O-ring191. Fourth clearance J4of about 0.12 mm is left between the flats188of the spacer187and the rectilinear portions162of the drive opening161. Finally, the spacer187is free to move radially along the oblong drive opening161over a length J5of about 0.5 mm, as a function of dispersion in the operation of the gearbox.

Thus, by means of this rotary drive device180, rotation of the planet carrier135drives the oil distribution system150in rotation. Nevertheless, these clearances J1to J5and the damper191, ensure that axial or radial movements of the gearbox3are not transmitted to the oil distribution system150. In addition, because of the plurality of rotary drive devices180that are distributed around the oil distribution system150, losses of alignment of the gearbox3are likewise not transmitted to the oil distribution system150.

The embodiments or implementations described in the present description are given by way of non-limiting illustration, and in the light of this description a person skilled in the art can easily modify these embodiments or implementations or can envisage others, while remaining within the ambit of the invention.

Furthermore, the various characteristics of these embodiments or implementations can be used singly or they may be combined within one another. When they are combined, these characteristics may be combined as described above or in other ways, the invention not being limited to the specific combinations described in the present description. In particular, unless specified to the contrary, a characteristic described with reference to any one embodiment or implementation may be applied in analogous manner to some other embodiment or implementation.