Abstract:
A propeller for an aircraft turbine engine comprising a plurality of vanes as well as a hub having a plurality of accommodating ports receiving the bases of said vanes, each vane base being rotatably mounted in its associated accommodating port. The propeller also has at least one vane retaining ring structure in the radial direction outwardly from the hub, being cladded around the latter.

Description:
TECHNICAL FIELD 
       [0001]    The present invention generally relates to turbine engine propellers for aircraft. It is applicable in particular to so-called “open rotor” turbojets, turboprops and turbine engines. 
       STATE OF PRIOR ART 
       [0002]    In reference to  FIG. 1 , it is represented a part of a propeller  1  of an open rotor type aircraft turbine engine, this propeller  1  being provided with a plurality of vanes  2 , a single one of which is visible in this  FIG. 1 . For information, as is known, such a turbine engine comprises two contrarotating propellers, with for example one propeller rotationally integral with a first power-free turbine and the other propeller being rotationally integral with a second power-free turbine, provided downstream of the one propeller. 
         [0003]    The propeller  1 , with a longitudinal axis  3 , includes a hub  4  centred on this axis and having a plurality of accommodating ports  5  circumferentially distributed, each receiving the base  8  of one the vanes  2 . For this, the accommodating ports  5  are made so as to pass through the hub, each by radially extending in the direction of the vane they accommodate, respectively. As visible in  FIG. 1 , each vane  2  has its base  8  rotatably mounted on the hub  4  about an axis  10 , for example using a ball bearing system  12  located between the base  8  and the accommodating port  5 . In this manner, using a suitable variable spacing system (not represented) judiciously cooperating with the vane  2 , the latter being permanently pivoted during operation of the turbine engine, depending on the desired incidence. 
         [0004]    The base  8  radially outwardly extends up to the outlet of its accommodating port  5  provided in the hub. Moreover, the vane comprises a blade part  14  lying in the jet, integrating a mechanical connection  18  with a reduced cross-section connecting it to the base  8 . Although not represented, this connection  18  can be integral with a tulip shaped piece, the head of which is accommodated within the blade part  14 , and the tulip stem consists of this connection  18  with a reduced cross-section. Furthermore, the tulip can be made as a single piece with the base  8 , for example of composite material, preferably comprising a blend of glass and/or carbon fibres with resin. 
         [0005]    Regarding the blade part  14 , only a portion of its streamlined hull  24  has been represented, this hull forming, between a leading edge  26  and the trailing edge  28 , the lower surface and the upper surface of the blade. This hull is also preferentially made as a single piece, for example of a composite material, preferably comprising a blend of glass and/or carbon fibres with resin. 
         [0006]    The hub  4  has thus the accommodating ports  5  circumferentially distributed, and made so as to be through holes. Furthermore, via these ports  5 , the hub allows for retaining the vanes  2  in the radial direction outwardly. 
         [0007]    If this technical solution is widespread, it has nevertheless the drawback that in case of a failure occurring in the hub, there is a not inconsiderable risk of losing the vane. 
       SUMMARY OF THE INVENTION 
       [0008]    One object of the invention is thus to provide a propeller for an aircraft turbine engine at least partially remedying the above-mentioned drawback, relating to systems of prior art. 
         [0009]    For this, one object of this invention is a propeller for an aircraft turbine engine comprising a plurality of vanes as well as a hub having a plurality of accommodating ports receiving the bases of said vanes, each vane base being rotatably mounted in its associated accommodating port. According to the invention, said propeller also has at least one vane retaining ring structure in the radial direction outwardly from the hub, being cladded around the latter. 
         [0010]    Thus, in case of a failure of the hub in its vane retaining function in the radial direction outwardly, one or more dedicated structures can continue to fulfil this role. The vane loss risks are thus substantially reduced thanks to this additional retaining structure, the placement of which around the hub turns out to be particularly easy. 
         [0011]    Preferably, each vane retaining ring structure is provided with at least a tightening device in the circumferential direction. This device, similar to a tensioner, therefore allows to provide an appropriate tightening of the retaining ring structure, about the hub. 
         [0012]    Preferably, for each vane retaining ring structure, a groove is provided circumferentially extending on one of the two elements among the hub and the structure, as well as a projection circumferentially extending on the other of said two elements, and accommodated in said groove. 
         [0013]    This assembly allows to obtain a good hold of the retaining ring structure on the hub of the propeller, since these circumferential elements prohibit a relative movement in the axial direction between the structure and the hub. Above all, upon tightening the structure, this can be relatively moved with respect to the hub along the circumferential direction by relatively sliding the projection in the groove, without the risk of being axially moved with respect to the hub. 
         [0014]    Preferably, each structure is made from at least two angular sectors mounted one to the other. This makes it easier mounting the retaining structure onto the hub. 
         [0015]    Finally, two structures are preferably provided, respectively provided on either side of the transverse plane integrating the axes of rotation of the vanes. Thus, in case of a failure of one of the two structures, the other remains active and can ensure alone the vane retaining in the radial direction outwardly. This provides a safety function in case of a failure, also called the “Fail Safe” function. 
         [0016]    Another object of the invention is also a turbine engine for an aircraft comprising at least one propeller such as that described above. 
         [0017]    Preferentially, a turbine engine is a turbojet, a turboprop or an “open rotor”. Thus, in the case of a turbojet, the vanes of the blower, whereas in the next two cases, it is about the vanes of the propellers. 
         [0018]    Finally, another object of the invention is an aircraft comprising a plurality of turbine engines such as that mentioned above. 
         [0019]    Further advantages and characteristics of the invention will become clearer from the non-limiting detailed description given below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    This description will be made with regard to the appended drawings wherein: 
           [0021]      FIG. 1 , already described, represents a partial half-cut longitudinal front view of a propeller known in the prior art, this schematic view being also applicable to the present invention; 
           [0022]      FIG. 2  represents a partial half-cut longitudinal front view of a propeller according to a preferred embodiment of the present invention; 
           [0023]      FIG. 3  represents a cross-section view taken along line III-III of  FIG. 2 ; and 
           [0024]      FIG. 4  represents a view similar to that of  FIG. 2 , on which the propeller is in the form of another preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0025]    In reference to  FIG. 2 , there is seen an “open rotor” type turbine engine propeller  1  according to a preferred embodiment of the present invention, in which turbine engine two contrarotating propellers are respectively rotationally driven by two power-free turbines. This propeller  1  has all the characteristics of the propeller shown in  FIG. 1 . Besides, in the figures, elements having the same number references correspond to identical or similar elements. 
         [0026]    Thus, it can be seen in this preferred embodiment that two structures  40  providing retaining ring for the vanes  2  in the radial direction outwardly have been added. These two structures  40  are respectively provided on either side of a transverse plane P integrating the axes of rotation  10  of the vanes, and more precisely on either side of the connections  18  thereof, by a distance from which they are positioned. 
         [0027]    The structures  40  are outwardly cladded on the hub  4 . Indeed, as can be seen in  FIG. 2 , each structure  40  is preferentially cladded against the outside surface  46  of the hub at which the ports  5  emerge, and also preferentially against the top surface  48  of the vane base  8 . 
         [0028]    In  FIG. 3 , it can be seen that the hub  4  has the form of an annular base  4   a  through which are provided the accommodating ports  5  which are circumferentially distributed, each of which radially extending outwardly via a flange  4   b . Besides, it is in this flange  4   b  that is preferentially arranged the ball bearing system  12  for cooperating with the base  8  in order to allow pivoting of the vane in its port  5 , and thus to adjust its incidence. 
         [0029]    Here, the outside surface  46  of the hub, against which the retaining structure  40  is cladded thus consists of the radially outer ends of the flanges  4   b . Consequently, the parts of the retaining structure  40  arranged between consecutive flanges  4   b  lie facing away the base  4   a  of the hub  4  radially positioned inwardly. 
         [0030]    In a preferred embodiment, the structure  40  is sectored in order to make the mounting thereof easier. Consequently, a plurality of ring angular sectors  40 ′ are provided mounted end to end by lock/unlock devices  40 ″. The number of ring angular sectors  40 ′, identical to the number of lock/unlock devices  40 ″, is for example between three and six. Furthermore, the sectors  40 ′ are preferably of the same angular length. 
         [0031]    In the preferred embodiment represented in  FIG. 3 , among the four lock/unlock devices  40 ″ inserted between the four ring sectors  40 ′, at least one of them further fulfils a tightening function in the circumferential direction. By actuating this device  40 ″, thus similar to a tensioner, the structure  40  has its circumferential length decreased, which results in an increased tightening of the hub  4 . 
         [0032]    As has been schematically shown, the lock/unlock devices  40 ″ are preferentially arranged between the flanges  4   b  of the hub  4 , so as to be located at parts of the structure  40  arranged away from the hub, and more precisely away from its base  4   a.    
         [0033]    In the other embodiment shown in  FIG. 4 , there has been further added for each structure  40 , on the angular sectors defining it, a projection  50  circumferentially and radially extending outwardly, by being centred on the axis  3 . This projection  50 , which can thus be interrupted in the circumferential direction because of the sectorization of the structure  40 , is accommodated in a groove  52  circumferentially extending and radially open outwardly, by being centred on the axis  3 . This groove  52  is provided on the hub  4 , and more precisely on its outside surface  46 . Thus, each of both grooves  52  is therefore interrupted along the circumferential direction between the flanges  4   b  which define the outside surface  46 . 
         [0034]    With this configuration, upon tightening the structure  40  by the devices  40 ″, this structure can be relatively moved with respect to the hub  4  along the circumferential direction by relatively sliding the projection  50  into the groove  52 , without the risk of being axially moved with respect to the hub  4 . 
         [0035]    Of course, various alterations can be made by those skilled in the art to the invention just described, only by way of non-limiting examples.