Patent Publication Number: US-2023139285-A1

Title: Device for distributing oil from a rolling bearing for an aircraft turbine engine

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a device for distributing oil from a rolling bearing for an aircraft turbine engine. 
     TECHNICAL BACKGROUND 
     The prior art comprises in particular the documents FR-A1-2 949 138, FR-A1-3 035 154, FR-A1-3 066 549, FR-A1-3 073 558, US-A1-2015/275760 and WO-A1-2015/075355. 
     In a known way, a turbine engine comprises a certain number of rolling bearings which are intended to support the rotor of the turbine engine in rotation, in particular with respect to a stationary support such as the casing of the latter. 
     During operation, the oil is typically injected on the rollings of these bearings so as to lubricate and cool them. To prevent the oil from spreading throughout the engine, it is necessary to confine the rolling bearings inside oil enclosures and to ensure a sealing of these oil enclosures from air enclosures adjacent to the engine, which must be free of oil. 
     More precisely, some oil enclosures are delimited between the shaft supported in rotation by the rolling bearing and an annular cover secured to a stationary support linked to the turbine engine casing and arranged around the shaft. A dynamic annular joint is typically positioned between the shaft and the cover to ensure a sealing between the oil enclosure and an adjacent air enclosure. Typically, the dynamic joint is mounted inside a flask that is attached to the cover. 
     The dynamic joints typically used in the rolling bearing oil enclosures for turbine engine are segmented radial joints (SRJ), comprising a plurality of annulus segments distributed circumferentially around a joint track rotating with the shaft of the rotor. These segments are in sliding contact with the joint track. The friction between the segments of the joint and the joint track generates heat that must be evacuated in order to maintain the mechanical integrity of these elements. One technique is to circulate cooling oil along the internal wall of the joint track. 
     The dynamic joint can be located right next to a rolling bearing that is lubricated by oil during operation. It is known to lubricate a rolling bearing by means of an oil distribution ring. The rolling bearing is mounted on the oil distribution ring, which comprises a scoop for recovering oil projected by a sprinkler, in order to collect this oil and supply a lubricating circuit for the bearing. 
     The present invention proposes an improvement to this technology which, in particular, allows to ensure the immobilisation, particularly in terms of rotation, of parts relative to one another in the restricted environment of an oil distribution device. 
     SUMMARY OF THE INVENTION 
     The invention relates to a device for distributing oil from a rolling bearing for an aircraft turbine engine, comprising:
         a rolling bearing comprising two rings, respectively internal and external,   an oil distribution ring configured to be mounted on a turbine engine shaft, this distribution ring comprising:
           i) an external cylindrical surface for mounting the internal ring of the bearing,   ii) an annular shoulder for supporting a first axial end of the internal ring, and   iii) an oil recovery scoop feeding a lubrication circuit of said bearing,   
           an annular track of a dynamic joint,       

     characterised in that it further comprises a nut screwed onto a thread of the distribution ring and being axially supported on a second axial end of the internal ring in order to tighten it axially against said shoulder, and in that said annular track is configured so as to be in axial support on said distribution ring and comprises rotation-locking elements cooperating with complementary elements of the nut. 
     The internal ring of the bearing is thus tightened and immobilized axially between the shoulder of the distribution ring and the nut screwed onto this distribution ring. To prevent an accidental loosening and unscrewing of the nut, it is locked in rotation by the track of the dynamic joint. This track is in axial support on the distribution ring and is therefore located in the immediate vicinity of this distribution ring. The function of locking in rotation the tightening nut of the ring is therefore assigned to an existing part, namely the track of the dynamic joint. This function is therefore ensured without the addition of any parts, which is advantageous from the point of view of cost, overall mass of the device and axial overall dimension. 
     The device according to the invention may comprise one or more of the following characteristics, taken alone or in combination with each other:
         the distribution ring comprises an internal cylindrical surface for shrink-fitting onto said shaft,   said scoop and said shoulder are located at a longitudinal end of the distribution ring opposite said annular track,   the distribution ring comprises an internal annular rim for axially locking this ring on said shaft,   the annular track comprises an internal annular rim being supported axially on said annular rim of the ring,   the rim of the joint track comprises or carries axial pins engaged in notches or orifices in the rim of the ring and configured to be engaged in notches or orifices of said shaft,   the locking elements are formed by axial fingers which are regularly distributed around an axis of the device and are engaged into complementary recesses of the nut by dog clutch,   the distribution ring comprises a cylindrical wall axially engaged in an annular space of said annular track and defining in this space an annular passage for the circulation of oil from said circuit towards oil projection orifices located at the external periphery of said track,   said space is formed in an annular segment of U-shaped axial cross-section of said track, this annular segment comprising a cylindrical surface configured to cooperate with said dynamic joint.       

     The invention also relates to a turbine engine, in particular for an aircraft, comprising a shaft on which at least one device as described above is mounted, this shaft comprising a thread for screwing a nut for tightening said annular track and the distribution ring against a cylindrical shoulder of the shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Further characteristics and advantages will be apparent from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which: 
         FIG.  1    is a partial schematic half-view in axial cross-section of a turbine engine comprising an oil distribution device according to one embodiment of the invention, 
         FIG.  2    is a view similar to  FIG.  1    and shows the path of the oil in the device, 
         FIG.  3    is a partial schematic view of the device of  FIG.  1    in perspective and axial cross-section, 
         FIG.  4    is a larger scale view of a portion of  FIG.  3   , 
         FIG.  5    is a schematic perspective view of a detail of the device in  FIG.  1   , 
         FIG.  6    is a schematic perspective view of a detail of the device in  FIG.  1   , and 
         FIG.  7    is a view similar to  FIG.  1    and shows an alternative embodiment of the device according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG.  1    shows a partial schematic of an oil enclosure  2  of an aircraft turbine engine bearing. 
     This oil enclosure  2  is delimited, on the inner side, by a shaft  4  rotating about an axis X, and on the outer side by an annular cover  6  which is secured to a stationary support linked to a casing (not shown) of the turbine engine and which is arranged around the shaft  4 . 
     An oil distribution ring  5  is arranged around the shaft  4  coaxially to it, and is secured in rotation to it. 
     The oil enclosure  2  contains a bearing  8  comprising a plurality of rolling-elements  10  engaged between an internal ring  12  mounted on the distribution ring  5 , preferably by shrink-fitting, and an external ring  14  secured to the casing of the turbine engine. 
     In the example shown in the figures, the rolling-elements  10  are balls. Nevertheless, the type of rolling or rolling-elements is not limiting in the scope of the present invention. 
     Oil is injected into the oil enclosure  2  to lubricate and cool the rolling-elements  10  of the bearing. For this purpose, oil is circulated in a lubrication circuit  7  accommodated between the distribution ring  5  and the shaft  4 . 
     The oil is brought by an oil sprinkler  9 , which is here located upstream of the distribution ring  5  (the terms “upstream” and “downstream” here refer to the general flow of the gases in the turbine engine). The ring  5  is generally annular in shape around the axis X and comprises at its upstream end a centrifugal type scoop  11  for recovering the oil projected by the sprinkler  9 . This scoop is in the form of a cylindrical rim oriented upstream in the example shown. The scoop  11  extends around and away from the shaft  4  and defines with it an annular space for receiving oil from the sprinkler  9 . 
     The oil circuit  7  comprises lunulas  7   a ,  7   b  formed on an internal cylindrical surface  5   b  for shrink-fitting the distribution ring  5  on the shaft  4 . The lunulas  7   a ,  7   b  are of two types in the example shown in  FIGS.  3  and  4   . 
     The lunulas  7   a  of the first type extend over a portion of the longitudinal extent of the surface  5   b  and open at their upstream ends onto the upstream end of the ring  5 , radially inside the scoop  11 . Their downstream ends are connected to the radially internal ends of conduits  15  oriented substantially radially with respect to the axis X and opening at their radially external ends onto the surface  5   a  of the ring  5  on which the ring  12  of the bearing  8  is mounted. 
     The lunulas  7   b  of the second type extend over the entire longitudinal extent of the surface  5   b  and open at their upstream ends onto the upstream end of the ring  5 , radially inside the scoop  11 . Their downstream ends open onto the downstream end of the ring  5 , radially inside an annular oil deflector  32  provided on the ring  5 . 
     In the example shown, it can be seen that the sprinkler  9  is arranged downstream of a pin  4   b  formed in one part with the shaft  4 , and upstream of the bearing  8 . 
     To allow the ring  5  to be mounted by shrink-fitting onto the shaft  4  from the downstream side (this would not be possible from the upstream side due to the presence of the pin  4 ), the scoop  11  preferably has a minimum internal diameter greater than the minimum internal diameter of the surface  5   b . The minimum diameter of the scoop  11  may be defined by an internal annular rim provided at the upstream free end of the latter. 
     The ring  5  thus comprises a deflector  32  which is in the form of a cylindrical wall centred on the axis X. In the example shown, this wall has a thin radial thickness and in particular is less than the minimum radial thickness of the rest of the ring  5 , comprising the scoop  11 . This deflector  32  may comprise on its internal cylindrical surface a projecting internal annular rib  32   a.    
     At its downstream end, the ring  5  also comprises a radially internal annular rim  13  which is supported axially upstream against a cylindrical shoulder  4   a  of the shaft  4 . An annular gorge  4   c  is located just upstream of this shoulder  4   a  and allows an optimum guiding of the force in the shaft  4  during the passage of torque between the shaft  4  and the distribution ring  5  shrink-fitted onto the shaft. 
     The internal ring  12  is in axial support upstream on an annular shoulder  5   e  of the ring  5 . Downstream of the surface  5   a  for mounting the internal ring  12 , the distribution ring  5  comprises an external thread  5   d  for screwing a nut  16  which is axially supported on the downstream end of the ring  12  in order to tighten it axially against the shoulder  5   e.    
     The oil enclosure  2  further comprises a sealing system intended to ensure a sealing of this oil enclosure relative from an adjacent air enclosure  20  which must be free of oil. 
     For this purpose, the sealing system comprises in particular a dynamic annular joint  22 . Typically, this dynamic joint  22  is composed of carbon annulus segments. The dynamic joint  22  is held in an annular flask  28  which is itself mounted inside the cover  6 . 
     The flask  28  has a portion of L-shaped cross-section which receives the dynamic joint  22 . 
     The dynamic annular joint  22  is associated with a joint track  26 , which is rotatable and carried by the shaft  4 . The track  26  comprises a contact surface  26   a , in sliding contact with the dynamic annular joint  22 . The contact surface  26   a  and the track  26  are treated to improve the joint/track sliding and minimize the wear of the dynamic annular joint  22 . 
     The joint track  26  is generally annular about the axis X and is generally U or C shaped in axial cross-section defining an annular space oriented axially, here upstream, i.e. towards the distribution ring  5 . 
     As can be seen in  FIG.  4   , the joint track  26  thus comprises two annular walls, respectively internal  26   b  and external  26   c , which are coaxial and extend one inside the other. The wall  26   c  comprises the cylindrical support and sliding surface  26   a  of the dynamic joint  22 . 
     The downstream ends of the walls  26   b ,  26   c  are connected by a median annular wall  26   d  oriented substantially radially with respect to the axis X. Each of the upstream ends of the walls  26   b ,  26   c  comprises an annular rim  26   e ,  26   f  also oriented radially. 
     The rim  26   e  extends radially inwards and opposite and downstream of the rim  13  of the distribution ring  5 . It is intended to be tightened axially against this rim  13 . 
     The rim  26   f  extends radially outwards and downstream of the nut  16 . It has a double function in the example shown. On the one hand, it is equipped with an annular row of fingers  27  oriented axially upstream and engaged between dog teeth  28  or similar elements of the nut  16 . This engagement ensures the locking in rotation of the nut  16  relative to the joint track  26  and thus relative to the ring  5  and the shaft  4 . 
     The rim  26   f  is also provided with a radially outward annular extension  29  which forms a drop thrower, i.e., an element for guiding and projecting oil drops by centrifuging during operation. 
     The annular space defined by the joint track  26  receives the deflector  32  of the distribution ring  5 , which is axially engaged from upstream in this space. In the mounting position shown in the drawings, the deflector  32  is spaced radially from the walls  26   b ,  26   c  by a predetermined and substantially constant distance. The deflector  32  is also axially spaced from the wall  26   d.    
     The deflector  32  defines within this space an annular oil flow passage of U-shaped cross-section from the outlets or downstream ends of the lunulas  7   b  to an axial clearance J provided between the nut  16  and the joint track  26 , at the level of the dog teeth  28  and the fingers  27  ( FIG.  4   ). Due to the presence of this clearance J, the dog teeth  28  and the fingers  27  define radial oil passage orifices between them. 
     The sealing system  22  also comprises a labyrinth joint  23  arranged downstream of the dynamic joint  22 , between a trunnion  21  mounted on the shaft  4  and the cover  6  ( FIG.  1   ). 
     The trunnion  21  is rotationally secured to the shaft  4  by means of splines  21   a . The trunnion  21  is located downstream of the distribution ring  5  and the joint track  26  and comprises an upstream end in axial support against the rim  26   e  of the joint track  26  or an annulus  24  interposed between this upstream end and the rim  26   e  ( FIG.  1   ). 
     A nut  33  is screwed onto the shaft  4 , downstream of the trunnion  21 , and is intended to be supported axially upstream to axially tighten the rims  13  and  26   e  between the shoulder  4   a  and the trunnion  21 . In addition, the ring  5  is preferably shrink-fitted onto the shaft  4  to ensure that it is centred as mentioned above. 
     As can be seen in  FIGS.  5  and  6   , the rim  26   e  of the joint track  26  carries axial pins  40  which are engaged in notches or orifices  41  in the rim  13  of the ring  5  and in notches  42  or orifices in the shoulder  4   a  of the shaft  4 . This cooperation allows to immobilize in rotation the joint track  26  relative to the ring  5  and the shaft  4 . It is thus understood that the nut  16 , which is immobilized in rotation relative to the joint track  26 , is also immobilized in rotation relative to the ring  5  and the shaft  4 . 
     In the example shown, the pins  40  are fitted and attached by shrink-fitting into blind holes in the rim  26   e  of the joint track  26 . 
       FIG.  2    shows schematically the oil flow path during operation by arrows. The oil is projected by the sprinkler  9  into the space delimited by the scoop  11  and enters the circuit  7 . Oil is supplied to the bearing  8  through the conduits  15  for its lubrication and into the passage defined between the deflector  32  and the joint track  26 . The oil flows through this passage to cool the joint track  26  by conduction, and is then evacuated through the aforementioned clearance J to be projected by centrifugation by the drop thrower formed by the extension  29 . 
     The variant embodiment of the device shown in  FIG.  7    differs from the previous embodiment essentially in that the centrifugal type scoop  11  is replaced by a centripetal type scoop  11 ′. 
     The device according to the invention allows, in particular, to ensure a locking in rotation of the nut  16  for axial immobilisation of the bearing  8 , and this with an optimised axial and radial overall dimension. It also allows to ensure an optimum cooling of the joint track  26  in this restricted environment.