Abstract:
A sealing device for a turbine engine bearing oil enclosure including a rotor shaft; an annular cover secured to an engine casing and arranged around the rotor shaft to co-operate therewith to define an oil enclosure that is to receive a bearing rotatably supporting the rotor shaft relative to the engine casing; a labyrinth seal mounted on the rotor shaft facing one end of the cover; an annular rim mounted inside the cover; a dynamic annular gasket interposed radially between the rim and the rotor shaft; and a clip for axially blocking the rim inside the cover and including at least one latch passing radially through the rim and being received radially inside a groove formed in the cover, is provided.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to the general field of oil enclosures for a rolling bearing in a turbine engine. The invention relates more particularly to a device for providing such an enclosure with sealing relative to a neighboring air enclosure. 
     In known manner, a turbine engine has a certain number of rolling bearings that are for providing rotor shaft of the engine with rotary support, in particular relative to a stationary support connected to a casing of the engine. 
     In operation, oil is typically injected onto the rolling elements of such bearings in order to lubricate them and to cool them. In order to prevent the oil from spreading throughout the engine, it is necessary to confine rolling bearings inside oil enclosures and to provide such oil enclosures with sealing relative to neighboring air enclosures of the engine, which often need to be free of oil. 
     More precisely, certain oil enclosures are defined between the rotor shaft given rotary support by the rolling bearing and an annular cover that is secured to a stationary support connected to the engine casing and arranged around the rotor shaft. A dynamic annular gasket is generally positioned between the rotor shaft and the cover in order to provide sealing between the oil enclosure and an air enclosure neighboring it. Typically, the dynamic gasket is mounted inside a rim, which is itself fastened to the cover by means of a plurality of fastener screws. 
     Nevertheless, such a configuration presents certain drawbacks. In particular, the heads of the screws fastening the rim to the cover are often to be found on the path of the flow of oil injected into the oil enclosure in order to lubricate and cool the roiling elements of the bearing, running the risk of oil splashing and running off in ways that can lead to leaks to the neighboring air enclosure. In addition, the zone where the dynamic annular gasket is mounted is difficult to access, since it is located in a confined space. There therefore exists a need to make it easier to mount the gasket between the rotor shaft and the cover. 
     OBJECT AND SUMMARY OF THE INVENTION 
     An object of the present invention is thus to provide a sealing device for a turbine engine bearing oil enclosure that does not present the above-mentioned drawbacks. 
     In accordance with the invention, this object is achieved by a sealing device comprising a rotor shaft, an annular cover secured to an engine casing and arranged around the rotor shaft to co-operate therewith to define an oil enclosure that is to receive a bearing rotatably supporting the rotor shaft relative to the engine casing, a labyrinth seal mounted on the rotor shaft facing one end of the cover, an annular rim mounted inside the cover, a dynamic annular gasket interposed radially between the rim and the rotor shaft, and a clip for axially blocking the rim inside the cover and including at least one latch passing radially through the rim and being received radially inside a groove formed in the cover. 
     The sealing device of the invention is remarkable in particular in that it does not have screws for fastening the rim to the cover. This fastening is provided by the blocking clip that has a latch passing radially through the rim and that is received radially inside a groove formed in the cover (which groove may be an annular groove or a notch). The lack of screws thus avoids any risk of causing oil to splash and run off in a manner that can lead to leaks towards the neighboring air enclosure. Given the location of the labyrinth seal, the zone in which the dynamic gasket is mounted can be accessed only from beside the bearing in the oil enclosure. The proposed fastening is then particularly advantageous since it makes it possible for mounting to be simple and access to the dynamic annular gasket to be facilitated. 
     In an embodiment, the axial blocking clip comprises a resilient pin that is received inside the rim and that is provided with a latch passing radially through the rim and being received radially inside the groove formed in the cover, and means for locking the resilient pin inside the rim. 
     In this embodiment, the axial blocking clip may include at least one catch secured to the resilient pin for being received radially in a hole formed in the rim so as to lock the resilient pin inside the rim. 
     Alternatively, the axial blocking clip may include at least one stud forced radially into a hole formed in the rim and coming into radial abutment against the resilient pin to lock it inside the rim. 
     In another embodiment, the axial blocking clip comprises a rigid pin received inside the rim and provided with a latch passing radially through the rim and being received radially inside the groove formed in the cover, and a flexible holder pin for holding the rigid pin inside the rim. 
     In this other embodiment, the flexible holder pin may come circumferentially into abutment against the rigid pin and may include projections projecting radially outwards for blocking the flexible holder pin inside the rim by expansion of the pin. 
     Likewise, the flexible holder pin may include a latch passing radially through the rim and received radially inside the groove formed in the cover. Under such circumstances, the latch of the rigid pin and the latch of the flexible holder pin are preferably diametrically opposite each other, thereby improving the axial blocking of the rim inside the cover. 
     Preferably, the rim includes, at an upstream end, a shoulder projecting radially outwards and axially upstream relative to the cover. 
     The invention also provides a turbine engine including at least one bearing oil enclosure provided with a sealing device as defined above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other characteristics and advantages of the present invention appear from the following description made with reference to the accompanying drawings, which show embodiments having no limiting character. In the figures: 
         FIG. 1  is a diagrammatic section view of a sealing device of the invention in its environment; 
         FIG. 2  is a side view of an axial blocking clip of the sealing device in an embodiment of the invention; 
         FIG. 2A  is a fragmentary view showing a variant embodiment of the blocking of the clip in the  FIG. 2  sealing device; 
         FIGS. 3 to 5  are side views of an axial blocking clip of the sealing device in other embodiments of the invention; and 
         FIG. 6  is a section view on VI-VI of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a diagrammatic and fragmentary view of an oil enclosure  2  for a turbine engine bearing to which the invention applies. 
     This oil enclosure  2  is defined on the inside by a rotor shaft  4 , and on the outside by an annular cover  6  that is secured to a support fastened to the casing of the turbine engine and that is arranged around the rotor shaft  4 . 
     This oil enclosure  2  contains a bearing  8  having a plurality of rolling elements  10  engaged between an inner ring  12  mounted on the rotor shaft  4  of the engine and an outer ring  14  secured to a casing of the engine (not shown in the figure). 
     Furthermore, oil is injected into the oil enclosure  2  in order to lubricate and cool the rolling elements  10  of the bearing. For this purpose, oil flows from upstream to downstream inside axial ducts  16  made along the rotor shaft  4  and opening out radially firstly in register with the rolling elements  10  by passing through the inner ring  12  of the bearing, and secondly downstream therefrom at a “droplet-launcher”  18  for centrifuging cooling oil from a gasket  22  towards the largest inside radius of the oil enclosure and to deflect particles of oil away from the sealing device described below (the path followed by the oil is represented by arrows in  FIG. 1 ). 
     Downstream from the droplet-launcher  18 , the oil enclosure  2  has a sealing device in accordance with the invention for providing the oil enclosure with sealing relative to a neighboring air enclosure  20  that must be free of oil. 
     To this end, the sealing device of the invention comprises in particular a dynamic annular gasket  22  that is associated with a rotary surface  24  of the droplet-launcher  18  carried by the rotor shaft  4 . Typically, the dynamic gasket  22  is made up of carbon ring segments and the rotary surface  24  is treated to improve segment-on-track sliding. Furthermore, it can be seen in  FIG. 1  that a portion of the oil flows under the rotary surface  24  so as to lubricate it and cool it, with its heating being a result of coming into contact with the dynamic gasket  22 . 
     The dynamic gasket  22  is held in an annular rim  26 , itself mounted inside the cover  6 . The rim  26  has a portion  26   a  of L-shaped section that receives the dynamic gasket  22  and that is extended downstream by an annular collar  26   b.    
     The rim  26  is mounted as a sliding fit inside the cover  6 . The portion  26   a  of L-shaped section presents grooves on the outside that receive O-rings  28  for providing sealing with the cover  6 ; 
     Furthermore, the rim  26  is blocked axially inside the cover  6  by means of an axial blocking clip  30 , various embodiments of which are described below with reference to  FIGS. 2 to 6 . 
     Downstream from the dynamic gasket  22 , the device of the invention for sealing the oil enclosure  2  also has a labyrinth seal  32  that is mounted on the rotor shaft  4  that has its static portion  34  carried by the cover  6 , at a downstream end thereof. This labyrinth seal  32  serves to limit the drop of air pressure in the air enclosure  20  in the event of carbon segments constituting the gasket  22  being destroyed. 
     With reference to  FIGS. 2, 2A, and 3 to 6 , there follows a description of various embodiments of the clip for axially blocking the rim  26  inside the cover  6 . 
     In the embodiment of  FIG. 2 , the axial blocking clip  30  comprises a resilient pin  36  that is received radially inside the rim  26 . 
     This resilient pin  36  is in the form of half an annulus centered on the longitudinal axis X-X of the engine and when in position it is received inside an annular groove  37  centered on the axis X-X and formed in the collar  26   b  of the rim ( FIG. 1 ). 
     At equal distances from its two free ends  36   a  and  36   b,  the resilient pin is provided with a latch  38  that, when in position, is to pass radially through the rim (and more precisely its collar  26   b ) and be received radially inside an annular groove  40  formed in the cover  6  all around its circumference. In a variant, and as shown in part in  FIG. 2A , the latch  38  of the resilient pin can pass radially through the rim and be received inside a notch  40 ′ formed in the cover  6 . 
     Furthermore, means are provided for locking the resilient pin  36  in position inside the rim  6 . Thus, in the embodiment of  FIG. 2 , the axial blocking clip  30  has two catches  42 , each secured to a free end  36   a,    36   b  of the resilient pin  36  and each being received, when in position, radially in a hole  44  formed in the rim so as to lock the resilient pin inside the rim. 
     Thus, in this embodiment, the catches  42  for locking the resilient pin inside the rim form integral portions of the resilient pin. While it is being put into place, the resilient pin  36  is moved axially from downstream to upstream inside the rim  6 , until in is received in the grooves  37  therein and until the catches  42  move as a result of the resilient pin expanding so as to be received inside the holes  44  of the rim and until the latch  38  becomes inserted in the annular groove  40  (or the notch  40 ′— FIG. 2A ) of the cover  6 . 
       FIG. 3  shows a variant embodiment of the means for locking the resilient pin  36  in position inside the rim  6 . In this variant, the axial blocking clip  30  has two studs  46  that are forced radially into holes  48  formed in the rim  26  and each of which comes into radial abutment against a free end  36   a  of the resilient pin in order to lock it inside the rim. Thus, the studs  46  and the resilient pin  36  block one another mutually. 
       FIG. 4  shows another embodiment of the clip  30 ′ for axially blocking the rim  26  inside the cover  6 . 
     In this embodiment, the axial blocking clip  30 ′ comprises a rigid pin  50  and a flexible holder pin  52 , each in the form of half an annulus centered on the longitudinal axis X-X of the engine, both of which are received radially inside the rim  6 . 
     The rigid pin  50  has a latch  54  that, when in position, passes radially through the rim (and more precisely its collar  26   b ) and is received radially inside an annular groove  40  (or a notch identical to that described with reference to  FIG. 2A ) formed in the cover  6 . 
     Furthermore, the flexible holder pin  52  has the function of holding the rigid pin  50  inside the rim. For this purpose, when in position, the flexible holder pin  52  comes into circumferential abutment against each free end  50   a  of the rigid pin. 
     In order to block the flexible holder pin  52  inside the rim, provision is made for it to have projections  56  (e.g. one projection at each of its free ends  52   a  and a projection halfway between its free ends) that project radially outwards and that, when in position, become blocked inside the groove  37  of the rim as a result of the flexible holder pin expanding. 
     The blocking clip  30 ′ is mounted as follows. The rigid pin  50  is initially inserted from downstream to upstream inside the rim  6  until it becomes received in the groove  37  therein, and until its latch  54  becomes inserted in the annular groove  40  (or the notch) in the cover  6 . Thereafter, the flexible holder pin  52  is inserted in the same manner, and its projections  56  become wedged by expansion inside the groove  37  of the rim, thereby holding the rigid pin in place. Advantageously, such assembly is particularly easy to implement, and is performed from beside the oil enclosure, the provision of the labyrinth seal  32  preventing assembly from another side. 
       FIGS. 5 and 6  show yet another embodiment of the clip  30 ″ for axially blocking the rim  26  inside the cover  6 . 
     This clip  30 ″ differs from that described with reference to  FIG. 4  in that the flexible holder pin  52  also has an additional latch  58  that, when in position, passes radially through the rim (and more precisely its collar  26   b ) and is received radially inside the annular groove  40  of the cover  6  (or where appropriate inside an additional notch). 
     Preferably, the latch  54  of the rigid pin  50  and the latch  58  of the flexible holder pin  52  are diametrically opposite each other. In this configuration, the flexible holder pin  52  has only two projections  56 , at each of its free ends  52   a.    
     As shown in  FIG. 6 , the latch  58  of the flexible holder pin is advantageously hinged relative to the flexible holder pin, thereby enabling the assembly to be given an axis for disengaging the flexible holder pin. 
     In an advantageous provision that is common to all of the embodiments described, the rim  6 , and more precisely its portion  26   a  of L-shaped section, includes a shoulder  62  at its upstream end projecting radially outwards and axially upstream relative to the cover  6 . 
     This shoulder  62  has two functions. Firstly it serves to channel oil running towards the low portion of the oil enclosure around the gasket, and secondly it serves as an extractor for removing the rim  26  from the cover (after removing the axial blocking pin) by means of tooling passing through the downstream bore of the rim.