Abstract:
A bearing support journal ( 100 ) for an internal shaft of a gas turbine engine comprising a means of retaining a sealing sleeve surrounding said shaft, the retaining means comprising:
       a full radial annular flange ( 132 ) formed upstream on an axial cylindrical part ( 130 ) of the journal ( 100 ), said full flange ( 132 ) being intended to butt axially against a radial annular flange of the sealing sleeve, and   tangential means ( 135 ) of immobilizing the sealing sleeve with respect to the journal ( 100 ), these being created downstream on the axial cylindrical part ( 130 ) of the journal ( 100 ).       
 
     The invention also relates to assembly of a journal ( 100 ) and of a sealing sleeve.

Description:
BACKGROUND OF THE INVENTION AND DESCRIPTION OF THE PRIOR ART 
       [0001]    The present invention relates to the field of gas turbine engines and deals more specifically with the operations involved in mounting the engine shaft. 
         [0002]    A twin-spool turbojet engine with a front-mounted fan, for example, comprises a low-pressure spool, known as the LP spool, and a high-pressure spool known as the HP spool. 
         [0003]    By convention, in the present application, the terms “upstream” and “downstream” are defined with respect to the direction in which air flows through the turbojet engine. Thus, a twin-spool turbojet engine with a front-mounted fan comprises, in the conventional way, from the upstream end downstream, a fan, an LP compressor stage, an HP compressor stage, a combustion chamber, an HP turbine stage and an LP turbine stage. 
         [0004]    By convention, in this application, the terms “interior” and “exterior” are defined radially with respect to the axis of the engine. Thus, a cylinder extending along the axis of the engine comprises an interior face facing toward the axis of the engine and an exterior surface, on the opposite side to its interior surface. 
         [0005]    The shaft of the LP spool is guided in its rotation in bearings supported by the fixed structure of the engine whereas the shaft of the HP spool is guided by bearings supported by the LP spool, the shafts of the two spools being concentric. 
         [0006]    The HP turbine disk is secured to a journal for the mounting of the bearing that allows the HP shaft to rotate with respect to the LP shaft, this bearing being known as bearing “4” in a twin-spool engine with a front-mounted fan. 
         [0007]    The LP shaft is housed in a cylindrical sleeve secured to the journal. When the sleeve is mounted in the engine, it is necessary to fix the position of the sleeve with respect to the journal, both axially and tangentially. 
         [0008]    To do this, with reference to  FIG. 1 , the journal  1  comprises an axial cylindrical part  13  on which dog couplings are formed. The dog couplings are in the form of a crenellated radial annular band  20  comprising projecting teeth  21  alternating with crenels  22 . Hereinafter, a crenel is defined as being the space between two successive teeth. 
         [0009]    Because the dog coupling teeth  21  of the journal  1  are directed inward, that is to say toward the axis of the engine, the dog couplings of the journal will be termed interior dog couplings. 
         [0010]    The interior dog couplings of the journal are designed to be in register with dog couplings, known as exterior dog couplings, formed on an annular band of the sleeve, the teeth of the exterior dog couplings being directed outward. 
         [0011]    Axial alignment between the teeth of the interior and exterior dog couplings allows the sleeve to be immobilized axially with respect to the journal, the upstream face of the teeth of the exterior dog couplings of the sleeve being in axial abutment against the downstream face of the teeth of the interior dog couplings of the journal. The sleeve is tangentially immobilized by upstream-directed axial engagement teeth formed on the labyrinth ring of the bearing which is mounted downstream of the sleeve. The axial engagement teeth are introduced between the teeth of the interior and exterior dog couplings, thus preventing the sleeve from rotating with respect to the journal about the axis of the engine. A locknut is screwed axially, in the cold state, onto the downstream end of the journal, to keep the sleeve axially and tangentially immobilized. 
         [0012]    The axial clamping applied by the locknut to the sleeve leads to high axial stresses on the interior dog couplings of the journal. The sharp edges and short radii of the teeth of the interior dog couplings lead to fatigue in the journal near said edges. The build-up of stresses of various kinds in the upstream part of the journal weakens the journal. 
         [0013]    The journal further comprises lubricating ducts placing the oil stored outside the journal in communication with the lubrication space in which the bearing supported by the journal is bathed. These internal lubricating ducts are formed longitudinally in the journal using an EDM (electron-discharge-machining) method. A method such as this has numerous disadvantages. First of all, it leads to an internal mechanical weakening of the machined zone. The thermally affected zone loses its mechanical properties, leading to a potential risk for damage. Further, the internal ducts formed by EDM are difficult to inspect because of their size and location on the component. After they have been formed, they may have internal cracks liable to weaken the journal. 
         [0014]    Finally, the internal lubricating ducts open into the lubricating space via radial oil removal ports. The sharp edges of the ports lead to mechanical weaknesses in the journal. 
         [0015]    Thus, the journal is the site of a buildup of mechanical fatigue phenomena which are liable to weaken the journal as it operates. 
       SUMMARY OF THE INVENTION 
       [0016]    In order to eliminate these disadvantages, the applicant company is proposing a bearing support journal for an internal shaft of a gas turbine engine comprising a means of retaining a sealing sleeve surrounding said shaft, the retaining means comprising:
       a full radial annular flange formed upstream on an axial cylindrical part of the journal, said full flange being intended to butt axially against a radial annular flange of the sealing sleeve, and   tangential immobilizing means created downstream on the axial cylindrical part of the journal and intended to immobilize the sealing sleeve tangentially with respect to the journal.       
 
         [0019]    What is meant by a full flange is a continuous flange the radial dimension of which is substantially constant around the journal. 
         [0020]    The tangential and axial stresses are spatially separated on the journal, the tangential stresses being located downstream while the axial stresses are located upstream. That advantageously makes it possible to limit the fatigue relative to each type of stress. 
         [0021]    As a preference, the tangential immobilizing means are formed at the downstream end of the axial cylindrical part of the journal. 
         [0022]    Again as a preference, the tangential immobilizing means are in the form of a crenellated radial annular immobilizing band formed in the interior surface of the journal, said band comprising inwardly directed radial teeth alternating with crenels. The crenels of the crenellated band form indexing means advantageously making it possible to immobilize the sleeve tangentially with respect to the journal. 
         [0023]    Still as a preference, locking housings are formed in the crenels of said crenellated radial annular immobilizing band of the journal. 
         [0024]    According to another feature of the invention, the journal comprises bearing lubricating ducts in the form of longitudinal slots formed in the interior surface of the journal. 
         [0025]    The lubricating ducts are, on the one hand, visible, allowing them to be visually inspected and defects to be detected and, on the other hand accessible to peening tools to make it possible to limit the mechanical fatigue introduced as they are being machined. 
         [0026]    As a preference, radial lubricating bores are formed in the interior surface of the journal at the upstream end of the lubricating ducts. Because the ducts are visible, the lubricating bores can be peened in order to reduce the mechanical stresses caused by their sharp edges. 
         [0027]    The invention also relates to a gas turbine engine comprising a journal according to the invention. 
         [0028]    The invention also relates to an assembly of a journal as set out hereinabove and of a sealing sleeve comprising a radial annular flange, the assembly comprising:
       a lubricating ring in surface contact with the interior surface of the journal, which is in axial abutment, along its upstream edge, with a radial annular axial-thrust flange formed on the journal.       
 
         [0030]    The lubricating ring is advantageously able to cover the lubricating ducts of the journal and to guide the removal of bearing lubricating oil. 
         [0031]    As a preference, the lubricating ring comprises an annular oil-collecting groove in which radial openings are formed, the groove advantageously placing the lubricating ducts in fluidic communication with the bearing outer ring. 
         [0032]    Again as a preference, the lubricating ring comprises cylindrical lands to deaden the vibrations of the engine in operation. 
         [0033]    Still as a preference, the assembly comprises a sealing disk, of cylindrical shape, that fits axially into the sealing sleeve downstream thereof, the sealing disk comprising a circumferential radial band comprising upstream-projecting axial teeth which are inserted into openings formed in the radial annular flange of the sealing sleeve. 
         [0034]    As a preference, the upstream-projecting axial teeth are in axial abutment against the full flange of the journal. 
         [0035]    As a preference, the sealing disk is mounted on the inside of the lubricating ring. 
         [0036]    The sealing disk is advantageously able to keep the lubricating oil upstream of its circumferential radial band. 
         [0037]    Still as a preference, the assembly comprises an external bearing ring, of cylindrical shape, that fits axially into the sealing disk downstream thereof, the external ring comprising upstream-projecting axial engagement teeth which are engaged between the downstream-projecting axial engagement teeth formed on the circumferential radial band of the sealing disk. 
         [0038]    Still as a preference, the bearing outer ring is mounted on the inside of the lubricating ring, thus allowing it to be lubricated in operation. 
         [0039]    According to another embodiment of the invention which has not been depicted, the lubricating ring is built into the bearing outer ring. 
         [0040]    As a preference, the assembly comprises a locking ring for locking the bearing outer ring, of cylindrical shape, that fits axially into the bearing outer ring, downstream thereof, mounted on the inside of the bearing support journal in order to lock the axial position of the bearing outer ring. 
         [0041]    Again as a preference, the locking ring comprises, upstream, interior radial locking teeth that axially immobilize the bearing outer ring and, downstream, exterior radial locking teeth that axially immobilize the lubricating ring. 
         [0042]    The locking ring allows the axial position of the outer ring and of the lubricating ring to be fixed. 
         [0043]    Still as a preference, locking housings intended to accommodate rotation-proofing pins to lock the tangential position of the bearing outer ring are formed in the downstream transverse face of the locking ring. 
         [0044]    As a preference, the assembly comprises an annular immobilizing ring, of cylindrical shape, that fits axially into the bearing outer ring downstream thereof, the immobilizing ring comprising upstream-directed axial immobilizing teeth designed to fix the tangential position of the outer ring with respect to the locking ring. 
         [0045]    Again as a preference, the bearing outer ring comprises on its downstream face downstream-projecting axial engagement teeth, each axial immobilizing tooth of the annular immobilizing ring being inserted between an interior radial locking tooth of the locking ring and a downstream-projecting axial engagement tooth of the outer ring. 
         [0046]    As a preference, the assembly comprises an axial locknut in axial abutment with the downstream face of the immobilizing ring. 
         [0047]    The invention also relates to a gas turbine engine comprising an assembly according to the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0048]    The invention will be better understood with the aid of the attached drawings in which: 
           [0049]      FIG. 1  depicts, in perspective, a sectioned view of a bearing support journal according to the prior art; 
           [0050]      FIG. 2  depicts, in perspective, a partial sectioned view of a bearing support journal according to the invention; 
           [0051]      FIG. 3  depicts another partial perspective view of the bearing support journal of  FIG. 2 ; 
           [0052]      FIG. 4  depicts a perspective view of a sealing sleeve according to the invention; 
           [0053]      FIG. 5  depicts a partial perspective view of a lubricating ring; 
           [0054]      FIG. 6  depicts a perspective view of the mounting of the lubricating ring of  FIG. 5  on the journal of  FIG. 3 ; 
           [0055]      FIG. 7  depicts another perspective view from beneath of the mounting of the lubricating ring of  FIG. 5  on the journal of  FIG. 3 ; 
           [0056]      FIG. 8  depicts a perspective view of a sealing disk according to the invention; 
           [0057]      FIG. 9  depicts a perspective view of a bearing outer ring according to the invention; 
           [0058]      FIG. 10  depicts a perspective view, from the downstream end upstream, of a locking ring according to the invention; 
           [0059]      FIG. 11  depicts a perspective view, from the upstream end downstream, of the locking ring of  FIG. 10 ; 
           [0060]      FIG. 12  depicts a perspective view of an immobilizing ring according to the invention; 
           [0061]      FIG. 13  depicts a perspective view of a locknut according to the invention; 
           [0062]      FIG. 14  depicts a perspective view of the sealing sleeve mounted with the lubricating ring and the journal, the journal and the lubricating ring being depicted with cutaway; 
           [0063]      FIG. 15  depicts a close-up view of  FIG. 14 ; 
           [0064]      FIG. 16  depicts, in perspective, the sealing disk mounted with the sealing sleeve, the lubricating ring and the journal of  FIG. 15 ; 
           [0065]      FIG. 17  depicts in perspective, the bearing outer ring mounted with the sealing disk, the sealing sleeve, the lubricating ring and the journal of  FIG. 16 ; 
           [0066]      FIG. 18  depicts, in perspective, the locking ring mounted with the bearing outer ring, the sealing disk, the sealing sleeve, the lubricating ring and the journal of  FIG. 17 ; 
           [0067]      FIG. 19  depicts a view in cross section, from the downstream end upstream, of the elements of  FIG. 18 ; 
           [0068]      FIG. 20  depicts a view in cross section, from the downstream end upstream, of the elements of  FIG. 19  after the outer ring has turned; 
           [0069]      FIG. 21  depicts, in perspective, the immobilizing ring mounted with the locking ring, the bearing outer ring, the sealing disk, the sealing sleeve, the lubricating ring and the journal of  FIG. 18 ; 
           [0070]      FIG. 22  depicts, in perspective, the locknut mounted with the immobilizing ring, the locking ring, the bearing outer ring, the sealing disk, the sealing sleeve, the lubricating ring and the journal of  FIG. 21 ; 
           [0071]      FIG. 23  depicts a view in cross section, from the downstream end upstream, of the elements of  FIG. 22 ; 
           [0072]      FIG. 24  depicts a perspective view of all the elements of  FIG. 23 ; and 
           [0073]      FIG. 25  depicts a side view of  FIG. 24  with part in cutaway. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0074]    A twin-spool turbojet engine with a front-mounted fan, for example, comprises a low-pressure spool, known as the LP spool, and a high-pressure spool known as the HP spool. 
         [0075]    The shaft of the LP spool is guided in rotation about the axis of the engine in bearings supported by the fixed structure of the engine whereas the shaft of the HP spool is guided by bearings supported by the LP spool, the shafts of the two spools being concentric. 
         [0076]    The HP turbine disk is secured to a journal for mounting the bearing that allows the HP shaft to rotate with respect to the LP shaft, via which the HP shaft is supported by the LP shaft. The LP shaft is housed in a cylindrical sealing sleeve  200  secured to the journal  100  as depicted in  FIG. 25 . The bearing comprises an inner ring, secured to the LP shaft, and an outer ring  500  secured to the journal  100 . 
         [0077]    Still with reference to  FIG. 25 , in order to keep the bearing outer ring  500  in position, the sealing sleeve  200 , a sealing disk  400  or bearing labyrinth ring  400 , the bearing outer ring  500  with a lubricating ring  300 , a bearing locking ring  600 , an immobilizing ring  700  and a locknut  800  are mounted from the upstream direction downstream on the journal  100 . All of these elements are axially and tangentially immobilized by the journal  100 . 
         [0078]    The various elements of the assembly will now be described individually. 
       Journal  100   
       [0079]    With reference to  FIGS. 2 and 3 , the journal  100  is in the form of a component exhibiting symmetry of revolution, widening substantially in the upstream direction and extending along the axis of the engine. The journal  100  comprises, from the upstream end downstream, a radial annular attachment part (not depicted) designed to be attached to a flange of the HP turbine disk, a frustoconical part  120  and a longitudinal cylindrical part  130 . 
         [0080]    The frustoconical part  120  of the journal  100  comprises a circumferential radial projecting portion  125 , that plays a mechanical reinforcement role, directed toward the axis of the engine and intended to transfer the mass of the journal  100  closer to the axis of the engine. The frustoconical part  120  of the journal  100  further comprises an interior frustoconical flange  127  intended to rest against the sealing sleeve  200  through which the LP shaft of the engine passes and form an air manifold. Circumferential ventilation openings  128  are formed in the frustoconical part  120  of the journal  100  to allow for the removal of a cooling airstream that has cooled the HP turbine disk mounted downstream of the journal  100 . 
         [0081]    The longitudinal cylindrical part  130  of the journal  100  furthest downstream along the journal  100  comprises, at its upstream end, a full radial annular flange  132  hereinafter termed full flange  132 . What is meant by a full flange is a continuous flange the radial dimension of which is substantially constant at the circumference of the journal  100 . The full flange  132 , formed on the interior surface of the journal  100 , is directed inward. The full flange  132  is not crenellated and is therefore not mechanically weakened. The full flange  132  is designed to immobilize the sealing sleeve  200  axially while at the same time allowing it to move tangentially. In other words, the sleeve  200  is free to rotate about the axis of the engine. 
         [0082]    With reference to  FIGS. 2 and 3 , the longitudinal cylindrical part  130  of the journal  100  comprises, at its downstream end, tangential immobilizing means in the form of a crenellated radial annular immobilizing band  135  comprising interior radial teeth  134  separated by crenels  131 . Locking housings  136  to accept rotation-proofing pins are formed in some of the crenels  131 . The radial teeth  134  of the immobilizing band  135  are directed inward. The immobilizing band  135  is designed to allow the sleeve  200  to be indexed with respect to the journal  100 , that is to say to immobilize it tangentially. The indexing of the sleeve  200  is indirect here because it is performed via elements that are mounted between the immobilizing band  135  and the sleeve  200 . 
         [0083]    The full flange  132  and the immobilizing band  135  form a means of retaining the sleeve  200  on the journal  100 . 
         [0084]    The axial immobilization performed by the full flange  132  at the upstream end, and the tangential immobilization performed by the immobilizing band  135  at the downstream end are advantageously spatially separated along the journal  100 . Mechanical stresses caused by these methods of immobilization are thus better distributed over the journal  100 . The journal  100  is less liable to be damaged by comparison with a journal according to the prior art. The full flange  132  allows axial load to be spread uniformly without creating any points of weakness. 
         [0085]    The longitudinal cylindrical part  130  of the journal  100  further comprises a radial annular axial-thrust flange  133  formed downstream of the full flange  132  and designed to form an axial end stop for the lubricating ring  300 . The radial annular axial-thrust flange  133  will hereinafter be known as the lubricating ring flange  133 . 
         [0086]    In this example, with reference to  FIG. 3 , the lubricating ring flange  133  is formed with the full flange  132  of the journal  100 . It goes without saying that the two flanges  132 ,  133  could just as well be independent. 
         [0087]    The lubricating ring flange  133  and the full flange  132  are, on the whole, in the form of a radial annular band with an annular radial portion offset in the upstream direction. In other words, the lubricating ring flange  133  and the full flange  132  are in the form of two treads of a staircase of which the faces facing in the downstream direction are designed to form axial end stops for the sleeve  200  and for the lubricating ring  300 . 
         [0088]    With reference to  FIG. 3 , the journal  100  comprises bearing lubricating ducts  110  in the form of longitudinal slots formed in the interior surface of the journal  100 . Radial lubricating bores  111  are formed in the interior surface of the journal  100  at the upstream end of the lubricating ducts  110 . Because the lubricating ducts  110  are visible, they can be visually inspected in order to detect any machining defects and repair these accordingly. Furthermore, the lubricating ducts  110  and the radial lubricating bores  111  here are peened in order to enhance their mechanical properties and reduce the stresses connected with their machining. 
       Sleeve  200   
       [0089]    With reference to  FIG. 4 , the sealing sleeve  200  is in the form of an annular cylinder extending axially, on the outside of the LP shaft of the engine and on the inside of the journal  100 . The sealing sleeve  200 , amongst other things, protects the LP shaft against excessive temperatures. 
         [0090]    The sealing sleeve  200  comprises, downstream, a cylindrical air circulation part  210  in which circular radial openings  211  are formed circumferentially. The sealing sleeve  200  further comprises, at its downstream end, a crenellated radial annular flange  220  intended to come into axial abutment against the full flange  132  of the journal  100 . The crenellated radial annular flange  220  comprises radial axial-thrust teeth  221  separated by indexing crenels  222 , the radial teeth  221  being directed outward. 
       Lubricating Ring  300   
       [0091]    With reference to  FIG. 5 , the lubricating ring  300  is intended to be housed on the inside of the journal  100 , in contact with the interior surface of the journal  100 . The lubricating ring  300  is in the form of an axial annular cylinder comprising, on its exterior surface, radial cylindrical lands  320  directed outward and designed to deaden the vibrations of the engine in operation. 
         [0092]    The lubricating ring  300  covers the lubricating ducts  110  formed in the interior surface of the journal  100 , the lubricating oil thus being advantageously guided between the journal  100  and the lubricating ring  300  through the lubricating slots  110  of the journal  100 . 
         [0093]    The lubricating ring  300  comprises, near its upstream end, an exterior annular oil-recovery groove  330  formed on its exterior surface and an interior annular oil-recovery groove  340  formed on its interior surface, the interior  340  and exterior  330  grooves being radially aligned. Radial openings  335  are machined in the grooves  330 ,  340  to place the lubricating oil circulating through the lubricating ducts  110  of the journal  100  in fluidic communication with the bearing mounted on the inside of the lubricating ring  300 . The radial openings  335  are, in this example, evenly distributed in the circumferential groove  330 ,  340  of the lubricating ring  300 . 
         [0094]    When the lubricating ring  300  is mounted with the journal  100 , as depicted in  FIGS. 6 and 7 , the upstream edge of the lubricating ring  300  is in axial abutment against the lubricating ring flange  133  of the journal  100 . The lubricating ring  300  is mounted axially from the rear end of the engine, that is to say from the downstream end upstream. The lubricating ring  300  is able to guide the removal of bearing lubricating oil toward the lubricating ducts  110  of the journal  100 . 
       Sealing Disk  400   
       [0095]    With reference to  FIG. 8 , the sealing disk  400  or bearing labyrinth ring  400  is in the form of an axial annular cylinder  410  comprising, downstream, an outwardly directed circumferential radial band  420 . The sealing disk  400 , mounted downstream of the sealing sleeve  200 , is designed to fit axially into the sealing sleeve  200 , on the inside of the lubricating ring  300 . 
         [0096]    The circumferential radial band  420  of the sealing disk  400  comprises upstream-projecting axial teeth  415  formed on the upstream surface of the band  420  and designed to be in register with the crenels  222  formed in the radial annular band  220  of the sealing sleeve  200 . In other words, each upstream-projecting axial tooth  415  of the sealing disk  400  engages between two radial teeth  221  of the radial annular band  220  of the sleeve  200 . 
         [0097]    The upstream-projecting axial teeth  415  of the sealing disk  400  are in this instance set in with respect to the radial exterior end of the circumferential radial band  420  of the sealing disk  400 . In other words, said teeth  415  are not formed in the extension of the exterior surface of the circumferential radial band  420  of the sealing disk  400  but are offset radially inward. 
         [0098]    Similarly, the circumferential radial band  420  of the sealing disk  400  comprises downstream-projecting axial teeth  425  formed on the downstream surface of the band  420  and designed to be in register with the bearing outer ring  500  mounted downstream of said sealing disk  400 . 
         [0099]    The downstream-projecting axial teeth  425  of the sealing disk  400  are here set in with respect to the radial exterior end of the circumferential radial band  420  of the sealing disk  400 . In other words, said teeth are not formed in the extension of the exterior surface of the circumferential radial band  420  of the sealing disk  400  but are offset radially inward. 
       Bearing Outer Ring  500   
       [0100]    With reference to  FIG. 9 , the bearing outer ring  500  mounted downstream of the sealing disk  400  is in the form of an axial annular cylinder designed to fit axially into the sealing disk  400  from the rear end of the engine, the outer ring  500  being mounted on the inside of the lubricating ring  300 . 
         [0101]    The bearing supporting the HP shaft comprises rollers held between the outer ring  500 , which rotates as one with the journal, and the inner ring (not depicted) which rotates as one with the LP shaft of the engine. 
         [0102]    The bearing outer ring  500  comprises upstream-projecting upstream axial engagement teeth  510  formed on the upstream face of the outer ring  500  and designed to engage between the downstream-projecting axial teeth  425 , formed on the circumferential radial band  420  of the sealing disk  400 . 
         [0103]    The upstream axial engagement teeth  510  of the outer ring  500  here are set in with respect to the exterior surface of the cylinder which embodies the shape of the outer ring  500 . In other words, said upstream axial engagement teeth  510  are not formed in the extension of the exterior surface of the cylinder but are offset radially inward. In this example, the upstream axial engagement teeth  510  have a radial thickness less than that of the cylinder that embodies the shape of the outer ring  500 . 
         [0104]    The bearing outer ring  500  further comprises downstream-projecting downstream axial engagement teeth  520  formed on the downstream face of the outer ring  500  and designed to engage with the locking ring  600  mounted downstream of said outer ring  500 . The downstream-projecting downstream axial engagement teeth  520  here are formed in the extension of the exterior surface of the cylinder. 
       Bearing Outer Ring  500  Locking Ring  600   
       [0105]    With reference to  FIGS. 10 and 11 , the bearing outer ring  500  locking ring  600  is in the form of an axial annular cylinder mounted on the inside of the bearing support journal  100  and designed to lock the axial position of the bearing outer ring  500 . The locking ring  600  is mounted from the rear end of the engine, downstream of the bearing outer ring  500  and of the lubricating ring  300 . 
         [0106]    The locking ring  600  comprises, upstream, interior radial locking teeth  610  designed to immobilize the bearing outer ring  500  axially and, downstream, exterior radial locking teeth  620  designed to immobilize the lubricating ring  300  axially. 
         [0107]    Locking housings  622  intended to accommodate rotation-proofing pins to lock the tangential and axial position of the bearing outer ring  500  are formed in the downstream transverse face of the locking ring  600 , between the exterior radial locking teeth  620 . In this example, one locking housing  622  is formed every two locking teeth  620  at the circumference of the journal as depicted in  FIG. 10 . 
         [0108]    A cylindrical annular land  630  is formed on the exterior surface of the locking ring  600 , the cylindrical land  630  being intended to come into contact with the interior surface of the journal  100 . 
       Annular Immobilizing Ring  700   
       [0109]    With reference to  FIG. 12 , the annular immobilizing ring  700 , mounted downstream of the locking ring  600 , is designed to fit axially from the rear into the bearing outer ring  500  and comprises upstream-directed axial immobilizing teeth  710 , designed to fix the tangential position of the bearing outer ring  500  with respect to the locking ring  600 . The axial immobilizing teeth  710  here are formed at equal distances from one another. 
         [0110]    Each axial immobilizing tooth  710  of the annular immobilizing ring  700  is inserted between an interior radial locking tooth  610  of the locking ring  600  and a downstream-projecting axial engagement tooth  520  of the outer ring  500 . The way in which the annular immobilizing ring  700  is mounted will be detailed later on. 
       Locknut  800   
       [0111]    With reference to  FIG. 13 , the axial locknut  800  is in the form of an axial annular cylinder mounted on the inside of the bearing support journal  100  downstream of the immobilizing ring  700 . The locknut  800  is mounted axially from the rear end of the engine. 
         [0112]    The axial locknut  800  comprises, at its downstream end, a crenellated annular radial band  820  comprising exterior radial teeth  821  separated by crenels  823 . Locking housings  822  are formed here in some crenels  823  to accept rotation-proofing pins that allow the various elements to be indexed as depicted in  FIG. 13 . 
         [0113]    Now that each of the elements has been described in isolation, the successive mounting of each of the elements from the rear end of the engine will now be described. 
         [0114]    First, with reference to  FIG. 6 , the lubricating ring  300  is introduced axially, from the rear end of the engine, inside the journal  100 . The exterior surface of the lubricating ring  300  is in contact with the interior face of the journal  100 . The upstream end of the lubricating ring  300  is in axial abutment against the lubricating ring flange  133 . 
         [0115]    Once the lubricating ring  300  has been mounted, the full flange  132  protrudes radially into the journal  100  to form an annular axial end stop of constant thickness. 
         [0116]    Second, with reference to  FIGS. 14 and 15 , the sealing sleeve  200  is introduced axially, from the rear end of the engine, into the journal  100 , the exterior radial teeth  221  formed upstream of the sleeve  200 , coming into axial abutment, along their upstream transverse faces, with the radial annular full flange  132  of the journal, along the downstream transverse face thereof. 
         [0117]    The sleeve  200  can no longer move further upstream with respect to the journal  100  (axial immobilization) but remains free to turn about the axis of the engine (tangential freedom). 
         [0118]    Third, with reference to  FIG. 16 , the sealing disk  400  is introduced axially, from the rear of the engine, into the journal  100  on the inside of the lubricating ring  300 . Each upstream-projecting axial tooth  415  of the sealing disk  400  engages between two radial teeth  221  of the radial annular band of the sleeve  200  to come into axial abutment against the full flange  132  of the journal  100 . 
         [0119]    The axial dimension of the upstream-projecting axial teeth  415  of the sealing disk  400  is substantially equal to that of the radial teeth  221  of the radial annular band of the sleeve  200  so that they fit into one another. Likewise, the circumferential dimension of the upstream-projecting axial teeth  415  of the sealing disk  400  is substantially equal to the circumferential dimension of the crenels formed between radial teeth  221  of the radial annular band of the sleeve  200 . 
         [0120]    Advantageously, when the sealing disk  400  is being introduced into sleeve  200 , the teeth of the sleeve  200  and the teeth of the sealing disk  400  come into register with one another and form a substantially continuous full annular band, the axial thickness of which is constant, as depicted in  FIG. 16 . 
         [0121]    In other words, assembling the sleeve  200  with the sealing disk  400  makes it possible to form a continuous axial end stop on the annular full flange  132  of the journal  100 . The axial stresses are therefore evenly distributed over the full flange  132 . 
         [0122]    The exterior surface of the circumferential radial band  420  of the sealing disk  400  is, for its part, pressed against the interior surface of a portion of the lubricating ring  300  extending between the upstream end of said ring  300  and the upstream end of the interior lubricating groove  340 . Thus, the interior lubricating groove  340 , comprising radial openings  335 , is radially aligned with the downstream-projecting axial teeth  425  of the sealing disk  400 . 
         [0123]    Fourth, with reference to  FIG. 17 , the bearing outer ring  500  is introduced axially, from the rear end of the engine, into the journal  100 , the exterior surface of the bearing outer ring  500  being in contact with the interior surface of the lubricating ring  300 . 
         [0124]    Each upstream-projecting axial engagement tooth  510  of the bearing outer ring  500  engages between two downstream-projecting axial teeth  425  formed on the circumferential radial band  420  of the sealing disk  400 . 
         [0125]    The axial dimension of the upstream-projecting axial engagement teeth  510  of the bearing outer ring  500  is substantially equal to that of the axial teeth  425  of the sealing disk  400  so that they can fit into one another. Likewise, the circumferential dimension of the upstream-projecting axial engagement teeth  510  of the bearing outer ring  500  is substantially equal to the circumferential dimension of the crenels, that is to say of the inter-tooth spaces, formed between the axial teeth  425  of the sealing disk  400 . 
         [0126]    When the bearing outer ring  500  is being introduced into the sealing disk  400 , the teeth of the bearing outer ring  500  and the teeth of the sealing disk  400  come into register with one another and form a substantially continuous full annular band, the axial thickness of which is constant. In this example, the radial cutouts are substantially equal in size. 
         [0127]    As described above, the upstream axial engagement teeth  510  of the outer ring  500  are set in here with respect to the radial exterior end of the cylinder that embodies the shape of the outer ring  500 . The same is true of the axial teeth  425  of the sealing disk  400  with respect to the radial outer end of the circumferential radial band  420  of the sealing disk  400 . 
         [0128]    In other words, when the bearing outer ring  500  is mounted with the sealing disk  400 , the assembly formed by the bearing outer ring  500  and the sealing disk  400  is substantially in the form of an axial annular cylinder having an exterior annular groove  350  formed by the collaboration of the teeth of the bearing outer ring  500  with the teeth of the sealing disk  400  which are set in (see  FIG. 17 ). The upstream and downstream parts of the axial annular cylinder correspond respectively to the sealing disk  400  and to the bearing outer ring  500 . 
         [0129]    The exterior annular groove  350  thus formed is radially aligned with the interior annular groove  340  formed in the lubricating ring  300 . That advantageously makes it possible for a lubricating passage to be formed between said grooves  330 ,  350  in order to lubricate the bearing. 
         [0130]    Fifth, with reference to  FIGS. 18 to 20 , the ring  600  that locks the bearing outer ring  500  is mounted axially, from the rear end of the engine, on the inside of the journal  100 . The locking ring  600  is mounted downstream of the bearing outer ring  500  and of the lubricating ring  300 . 
         [0131]    The cylinder that embodies the shape of the locking ring  600  has a diameter greater than the diameter of the cylinder that embodies the shape of the outer ring  500 , but smaller than the diameter of the cylinder that embodies the shape of the cylindrical downstream part of the journal  100 . 
         [0132]    The interior radial locking teeth  610  of the locking ring  600  come into axial abutment with the downstream face of the bearing outer ring  500  between its downstream axial engagement teeth  520 . The circumferential dimension of the interior radial locking teeth  610  is less than that of the crenels, that is to say of the inter-tooth spaces, between the downstream axial engagement teeth  520 . Thus, the locking ring  600  has some clearance to rotate about the axis of the engine. 
         [0133]    As the locking ring  600  is being introduced into the journal  100 , the exterior radial locking teeth  620  of the locking ring  600  penetrate the spaces between the interior radial teeth  134  of the upstream crenellated band  135  of the journal  100  as depicted in  FIG. 19 . The exterior radial locking teeth  620  of the locking ring  600  are in axial abutment with the downstream face of the lubricating ring  300 . 
         [0134]    With reference to  FIG. 20 , the locking ring  600  is rotationally driven about the axis of the motor in the counterclockwise direction so that the exterior radial locking teeth  620  of the locking ring  600  pass “behind” the interior radial locking teeth  134  of the upstream crenellated band  135  of the journal  100 . In other words, the downstream face of the exterior radial locking teeth  620  of the locking ring  600  is in contact with the upstream face of the interior radial teeth  134  of the immobilizing band  135  of the journal  100 . 
         [0135]    After rotation, and still with reference to  FIG. 20 , the locking housings  622  formed in the downstream transverse face of the locking ring  600  between the exterior radial locking teeth  620  are axially aligned with the crenels  131  of the crenellated radial annular immobilizing band  135  of the journal  100  in which housings  136  for rotation-proofing pins are formed. 
         [0136]    Sixth, with reference to  FIGS. 21 to 22 , the annular immobilizing ring  700  is introduced axially, from the rear end of the engine, inside the journal  100 . Each axial immobilizing tooth  710  of the annular immobilizing ring  700  becomes inserted between an interior radial locking tooth  610  of the locking ring  600  and a downstream-projecting axial engagement tooth  520  of the outer ring  500 . Mounting the annular immobilizing ring  700  makes it possible to eliminate the clearance that the locking ring  600  has to rotate about the axis of the engine. The circumferential dimension of the immobilizing teeth  710  of the immobilizing ring  700  is here designed to fill the circumferential space formed between an interior radial locking tooth  610  of the locking ring  600  and a downstream-projecting axial engagement tooth  520  of the outer ring  500 . 
         [0137]    Seventh, still with reference to  FIGS. 21 to 22 , the axial locknut  800  is introduced axially, from the rear end of the engine, into the journal  100  downstream of the immobilizing ring  700 . 
         [0138]    The locknut  800  is introduced into the journal  100  in the cold state. Because of thermal expansion, the locknut  800  expands transversely, the exterior radial teeth  821  of the nut  800  pressing against the interior surface of the journal  100 . Further, the nut  800  will axially restrain all of the elements mounted between the full flange  132  formed upstream of the journal  100  and said locknut  800 . 
         [0139]    The number of locking housings  822  formed between the exterior radial teeth  821  of the locknut  800  is greater by one than the number of locking housings  622  formed in the locking ring  600 . Thus, there is always a position in which a locking housing  822  formed between an exterior radial tooth  821  of the locknut  800  is axially aligned with a locking housing  622  formed in the locking ring  600 , which is itself axially aligned with a locking housing  136  formed in the journal  100 . 
         [0140]    With reference to  FIG. 23 , a rotation-proofing pin  850  is inserted longitudinally between the locking housings  622 ,  136 ,  822  of the locking ring  600 , of the journal  100  and of the locknut  800  in order to immobilize tangentially all of the elements mounted with the journal  100 . 
         [0141]    Thus, as can be seen from  FIGS. 24 and 25 , all the elements  200 - 800  are immobilized on the journal  100  both axially and tangentially. Tangential immobilization, advantageously offset toward the downstream end of the journal  100 , makes it possible to reduce the mechanical stresses near the full flange  132  of the journal  100  and thus increase its life. 
         [0142]    The bearing outer ring  500  described here is one that is mounted on the inside of a lubricating ring  300 , and is independent thereof. It goes without saying that the bearing outer ring  500  and the lubricating ring  300  could be mounted as a single same module or be in the form of a single element. The lubricating ring  300  may be incorporated into the bearing outer ring  500 .