Abstract:
A gearbox for driving equipment of a turbomachine, including a substantially V-shaped box having two arms joined together by a joining part, the arms containing gear trains joined together at the joining part, and an attachment to the turbomachine. The attachment include a mechanism for insetting and/or for attaching the joining part and a suspension device of the arms.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to the attachment of a substantially V-shaped gearbox for driving turbine-engine equipment, such as a turbojet engine or a turboprop engine of an aeroplane. 
         [0002]    The applicant has developed a gearbox of which the casing is substantially V-shaped and comprises two arms which are interconnected by a joining part. The arms enclose gear lines which are located in non-parallel planes and are joined to each other by at least one gear unit which is located in the part joining the arms. The gearbox further comprises means for attachment to a casing of the turbine engine. 
         [0003]    Constructing the kinematic chain in a plurality of gear lines which are located in non-parallel planes makes it possible to arrange even a gearbox having large dimensions entirely in the proximity of the casing of the turbine engine, without too much space being taken up in the radial direction, the axial direction or in the angular direction, since the box is not rectilinear. In addition, there are a large number of surfaces of the gearbox (which extend in very different directions) to choose from for positioning the equipment, and this also contributes to limiting the size of the assembly. 
         [0004]    It is important that the means for attaching the gearbox to the casing of the turbine engine are designed to minimise the deformations of said casing and to withstand the forces transmitted to the casing by the box during operation. 
         [0005]    The object of the present invention is in particular to meet these requirements in a simple, efficient and economical manner. 
       DISCLOSURE OF THE INVENTION 
       [0006]    The invention proposes a gearbox for driving turbine-engine equipment, comprising a substantially V-shaped casing and comprising two arms which are interconnected by a joining part which extends over part of the length of the arms, the arms being formed by two parts of said casing which are separate outside said joining part, the arms containing gear lines which are located in non-parallel planes and are interconnected in the region of the joining part, the gearbox further comprising means for attachment to the turbine engine, the attachment means comprising both means for embedding and/or attaching the joining part and means for the suspension of the arms. 
         [0007]    The gearbox is thus embedded in and/or attached to the turbine engine and suspended therefrom at the same time, and this ensures said box is well attached and meets the above-mentioned requirements. The gearbox can be mounted on the turbine engine such that the joining part thereof is oriented towards the upstream end and such that the arms thereof extend towards the downstream end. The gearbox thus comprises upstream embedding and/or attachment means and downstream suspension means. 
         [0008]    The casing of the gearbox preferably comprises a tubular member through which a shaft for driving the gear lines is intended to pass, said tubular member comprising an end which is connected to the part for joining the arms and an opposite free end part comprising the above-mentioned embedding and/or attachment means, the embedding and/or attachment means comprising, for example, an outer annular flange comprising screw-passage openings. 
         [0009]    Advantageously, each arm of the casing is articulated to an end of a connecting rod which comprises, at the opposite end thereof, means for attachment to the turbine engine, said attachment means for example being means for articulation to a casing of the turbine engine. Each connecting rod may comprise means for adjusting the length thereof. 
         [0010]    The arms of the casing are preferably interconnected by a transverse reinforcing member. This member rigidifies the casing of the box and thus limits the deformations thereof, in particular the fact that the arms move closer to and further away from each other. 
         [0011]    The reinforcing member and the connecting rods may be located substantially in the same plane. This makes it possible to ensure that the forces are well distributed and well transmitted during operation. 
         [0012]    One arm of the casing may be longer than the other arm. The transverse reinforcing member may be connected close to the downstream end of the shortest arm on one side and at a distance from the downstream end of the longest arm on the other side. 
         [0013]    The present invention also relates to a turbine engine, such as a turbojet engine or a turboprop engine of an aeroplane, characterised in that it comprises a gearbox as described above. 
         [0014]    Advantageously, the joining part of the gearbox is embedded in and/or attached to a hub of an intermediate casing of the turbine engine, and the arms of the gearbox are attached by connecting rods to the casing of a compressor, for example a high-pressure compressor, of the turbine engine. 
         [0015]    The connecting rods are preferably oriented tangentially relative to the compressor casing. This allows the forces transmitted to the casing to be limited to tangential forces, and this limits the deformations of the casing. 
         [0016]    The connecting rods may be articulated to a radially outer annular flange of the casing of the compressor. This flange locally rigidifies the casing. Connecting the connecting rods to this flange makes it possible to limit the risk of the casing deforming during operation. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0017]    The invention will be better understood and other details, features and advantages of the invention will emerge upon reading the following description given by way of non-limiting example and with reference to the accompanying drawings, in which: 
           [0018]      FIG. 1  is a schematic perspective plan view of a V-shaped gearbox of a turbine engine; 
           [0019]      FIG. 2  is a schematic perspective side view of the gearbox from  FIG. 1 ; 
           [0020]      FIG. 3  is a schematic perspective side view, viewed from downstream, of a turbine engine equipped with the gearbox from  FIG. 1 ; 
           [0021]      FIG. 4  is a schematic partial perspective view of the means for embedding and/or attaching the gearbox; 
           [0022]      FIG. 5  is a schematic perspective view of the means for the suspension of the gearbox; 
           [0023]      FIG. 6  is another schematic perspective view of the means for attaching the gearbox; and 
           [0024]      FIG. 7  is a view which corresponds to  FIG. 6  and shows a variant of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Reference is first made to  FIGS. 1 and 2 , which show a gearbox  10  for driving equipment (not shown) of a turbine engine, such as a turbojet engine or a turboprop engine of an aeroplane. 
         [0026]    This gearbox  10  is intended to transmit mechanical power originating from the turbine engine by means of a radial shaft protruding therefrom, and to transmit said power to equipment such as pumps, electrical generators, etc. The transmission is carried out by a kinematic chain made up of successive gear units, said chain being made up of gear lines  12  which are located in non-parallel planes and are schematically shown by dashed lines in  FIG. 1 . A gear line  12  is a set of adjacent gear units which mesh with one another in principle and of which the toothed wheels are located in the same plane or in parallel planes; in other words, the rotational axes of the toothed wheels are all in parallel (perpendicular to this plane or to these parallel planes), and the toothed wheels which mesh directly with one another are considered to extend in the same plane; however, the gear line may extend in parallel planes if toothed wheels are present which are aligned along the same rotational axis or if offsets are present in the teeth in the same gear unit. 
         [0027]    The gearbox  10  essentially comprises a kinematic chain which is made up of the set of toothed wheels, which mesh with one another so as to transmit a movement, within a casing  14 . This chain is connected to a drive shaft  16  which is the radial shaft of the turbine engine or an intermediate shaft, the chain also being connected to take-off shafts  18  for the movement of the equipment. The gearbox  10  is attached to the turbine engine and the equipment itself is attached to the gearbox  10 . 
         [0028]    The casing  14  of the gearbox  10  is substantially V-shaped and comprises two arms  20  which are interconnected at one of the ends thereof by a joining part  22  which extends over part of the length of the arms. In the example shown, the arms  20  are the same length, and the joining part  22  extends over substantially half the length of the arms  20 . The arms  20  are therefore formed by two parts of the casing  14  which are separate outside the joining part  22 . Each arm  20  comprises at least one side face for mounting the equipment. 
         [0029]    As can be seen in  FIG. 3 , the gearbox  10  is mounted on the body of the turbine engine  24 , which in this case is a bypass turbojet engine. The invention may also apply to a turboprop engine. Conventionally, this turbine engine  24  comprises, from upstream to downstream, a fan  26  that generates a flow that divides into two coaxial flows, the primary flow supplying the engine, which comprises a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine and an exhaust nozzle  28  for ejecting the combustion gases. The turbine engine  24  further comprises, between the low-pressure compressor and high-pressure compressor, a structural intermediate casing  30  which typically comprises an intermediate hub  31  surrounded by two respectively inner and outer coaxial cylindrical walls (not shown), which define the passage duct for the secondary flow and are interconnected by radial tubular arms which are used in general for the passage of sub-systems. 
         [0030]    In the example shown, the gearbox  10  is mounted downstream of the fan  26  in the space located between the casing  36  of the high-pressure compressor and the above-mentioned inner cylindrical wall (not shown) of the intermediate casing  30 . The gearbox  10  is positioned such that the joining part  22  thereof is oriented towards the upstream end and such that the arms  20  thereof extend towards the downstream end and are located symmetrically on either side of a plane passing through the longitudinal axis A of the turbine engine. In the same way, for certain turbine-engine or turboprop-engine architectures, depending on the casings, the gearbox may be positioned such that the arms thereof extend towards the upstream end. 
         [0031]    The gearbox  10  comprises, at the upstream end thereof, means  38  for attachment to and/or embedding in the hub  31  of the intermediate casing  30  ( FIG. 4 ) and, at the downstream end thereof, means  40  for suspension from the casing  36  of the high-pressure compressor ( FIGS. 5 and 6 ). 
         [0032]    The casing  14  of the gearbox  10  comprises, at the upstream end thereof, that is to say on the side of the joining part  22 , a tubular member  38  of which one end is connected to the casing  14  and of which the opposite free end part defines means for embedding in and/or attachment to the hub  31  of the intermediate casing  30 . This free end part of the member  38  is intended to be inserted into a cup  66  having a shape which is complementary to the hub  31 , and may comprise means for attachment to the cup  66  ( FIG. 4 ). In this case, said attachment means comprise an outer annular flange  62  which is rigidly connected to the free end part of the member  38  and is intended to be placed on a radially outer end of a radial cylindrical cup  66  of the hub  31 . The flange  62  comprises passage openings  64  for screws which are intended to be screwed into threaded openings in the periphery of the cup  66 . The above-mentioned drive shaft  16  is intended to pass through the member  38 . 
         [0033]    In addition to the embedding and/or the attachment of the joining part  22  in/to the body of the turbine engine, the arms  20  of the casing  14  are attached to this body by suspension means  40 , one embodiment of which is shown in  FIGS. 5 and 6 . 
         [0034]    In this case, the suspension means comprise two connecting rods  40 , each connecting rod  40  connecting one arm  20  to the body of the turbine engine and preferably to the casing  36  of the high-pressure compressor. Each connecting rod  40  has one end which is articulated to an arm  20  and one opposite end which is articulated to the casing  36  of the compressor. Each connecting rod  40  preferably comprises means  41  for adjusting the length thereof, it being possible for the connecting rod to comprise a threaded rod which is screwed to a greater or lesser extent into a threaded element in order to vary the length of the connecting rod and therefore the distance of the corresponding arm  20  from the body of the turbine engine. 
         [0035]    In the example shown, each connecting rod  40  is articulated about a shaft  42  which is supported by a yoke  44  which is attached to the casing  14  of the gearbox, for example in the region  46  shown by the dashed lines in  FIG. 2 . The opposite end of each connecting rod  40  is articulated about another shaft  48  supported by a yoke  50  which is attached to the casing  36  of the compressor, it being possible for said yoke  50  to be rigidly connected to an outer annular flange  52  of the casing of the compressor  36 ; said flange  52  is used, for example, to attach coaxial cylindrical walls of this casing. The shafts  42 ,  48  for articulating the connecting rods are preferably parallel to each other and to the longitudinal axis A of the turbine engine. 
         [0036]    The points for attaching the connecting rods  40  to the casing of the compressor  36  are preferably located such that the connecting rods are oriented tangentially relative to the casing  36 . In the example shown in  FIG. 6 , the yokes  50  which are rigidly connected to the casing of the compressor are located at approximately 3:30 pm and 8:30 pm relative to the axis A, using the analogy of a clock face. This orientation of the gearbox and the attachments thereof will preferably be retained, but any angular position on the casings could be implemented (over 360° of the casings). The forces from the gearbox  10  are thus transmitted to the body of the turbine engine in a shearing manner, and this reduces the risk of the casing  36  of the compressor deforming. In a variant, the yokes  50  which are rigidly connected to the casing of the compressor may be located in other positions relative to the axis A, such that, for example, the gearbox  10  is located on one side of the casing. 
         [0037]    In addition, to limit the risk of the casing  14  of the gearbox  10  being deformed and to improve the distribution of the stresses during operation, the arms  20  are interconnected by a transverse connecting rod  54  which extends between the arms, and of which the ends may be articulated to shafts  56  supported by yokes  58  which are rigidly connected to the arms ( FIGS. 5 and 6 ). This connecting rod  54  may advantageously be located close to the downstream or free ends of the arms, in order to allow the inter-arm forces to be absorbed and to thus prevent fluttering between the arms, which would lead to premature wear of the casing  14  of the gearbox  10 . The connecting rods  40  and  54  preferably extend in the same plane, which is for example perpendicular to the longitudinal axis A of the turbine engine. Therefore, continuity of the force path is ensured between the arms  20 , the connecting rods  40  and  54  and the casing  36  of the high-pressure compressor to which the connecting rods  40  are articulated. 
         [0038]    The variant in  FIG. 7  differs from the above-described embodiment in that the arms  20  are interconnected by a transverse rail  60 , of which the ends are attached to the arms, for example by welding or brazing points, screw/nut-type means, rivets, etc. The transverse rail  60  and the connecting rods  40  also preferably extend in the same plane, for the above-mentioned reasons relating to the continuity of the force path. 
         [0039]    Moreover, the arms  20  of the casing are not necessarily the same length. It may be advantageous to provide one arm to be longer than the other, so as to provide more possibilities for positioning the equipment. Such a configuration increases the risks of fluttering between the arms, and as a result it is particularly appropriate in this configuration to provide a transverse reinforcing member such as the connecting rod  54  or the transverse rail  60 , which interconnect the arms, in order to prevent such fluttering. It also remains preferable for the transverse reinforcing member and the connecting rods  40  to extend in the same plane. In this case, the transverse reinforcing member may advantageously be connected close to the downstream end of the shortest arm on one side and at a distance from the downstream end of the longest arm on the other side.