Abstract:
A planetary bolt ( 103 ) having a flange ( 109 ) and at least one through-bore with two open ends. The flange ( 109 ) contains the open ends and the flange ( 109 ) can be bolted to a planetary carrier ( 101 ).

Description:
[0001]    This application is a National Stage completion of PCT/EP2014/077697 filed Dec. 15, 2014, which claims priority from German patent application serial no. 10 2014 200 463.2 filed Jan. 14, 2014. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention concerns a planetary bolt and a planetary carrier, onto which the planetary bolt can be bolted. 
       BACKGROUND OF THE INVENTION 
       [0003]    Transmissions in wind turbines are exposed to high loads, which lead to distortions of the planetary carrier. To make the planetary carrier more rigid, the planetary bolts are fixed into the planetary carrier by means of a press fit. The press fit makes it possible to absorb bending moments through the planetary bolts. Moreover, by virtue of the press fit the planetary bolt is fixed in the axial direction. 
         [0004]    Particularly when conical roller bearings are used, the planetary bolts are loaded by forces in the axial direction. Consequently, corresponding forces in the radial direction act upon the press-fit connection between the planetary carrier and the planetary bolt. 
         [0005]    An obvious possibility for increasing the load-bearing capacity of press fits subjected to such forces and thereby improving the load-bearing capacity of the planetary bolts, would be to increase the dimensional difference between the planetary bolts and the bolt seats in the planetary carrier. This would increase the normal forces acting on the planetary bolts in the press-fit connections. However, during assembly the planetary carriers would have to be heated to a higher temperature before the planetary bolts could be inserted into the planetary carrier. This would involve a greater risk of burn injuries for the assembly workers. Furthermore, the stresses produced in the planetary carrier as a result of the press-fit connection would be greater. The higher load-bearing capacity of the planetary bolts would be offset by reduced load-bearing capacity of the planetary carrier. 
         [0006]    A solution for these problems is to combine the fixing of the planetary bolts by press-fitting, with bolting them in by means of screw-bolts. From the prior art corresponding solutions are known, in which the planetary bolts are fixed by screw-bolts into the planetary carrier. In this case the screw-bolts extend in the axial direction through the planetary bolts. For that purpose the planetary bolts have axially directed through-bores that pass completely through the planetary bolt, i.e. from one end face of the planetary bolt to an opposite end face. 
         [0007]    In this arrangement the screw joint is formed in the lateral part of the planetary carrier on the rotor side. This area, however, is subjected to high loads. Besides a load due to a rotor torque, a bending moment acts there because of the weight of the rotor. The screw joint imposes an additional load on the lateral part on the rotor side. Furthermore, the threaded bore required results in structural weakening. 
         [0008]    The screw-bolts used have to be correspondingly long. Consequently, the axial rigidity of the screw-bolts is low. Thus, when acted upon by a load in the axial direction the screw-bolts are comparatively compliant. When a planetary bolt is severely loaded in the axial direction, this can result in a displacement of the planetary bolt relative to the planetary carrier. This brings the risk that the planetary bearing will lose its prestress or that the bearing play will change. The result is damage to the bearing. 
         [0009]    Furthermore, it is possible that the planetary gearwheels will be displaced in the axial direction relative to the ring gear. This can result in damage to the ring gear and the planetary gearwheels. 
       SUMMARY OF THE INVENTION 
       [0010]    The purpose of the present invention is to fix a planetary bolt into a planetary carrier while circumventing the disadvantages inherent in the solutions known from the prior art. In particular, the load-bearing capacity of the planetary bolt in the axial direction should be improved. 
         [0011]    This objective is achieved by a planetary bolt as described below and a planetary carrier for receiving the planetary bolt, such that a flange of the planetary bolt can be bolted onto the planetary carrier. 
         [0012]    According to the invention, the planetary carrier is provided with at least one through-bore which has two open ends. The through-bore passes completely within the flange. Correspondingly, the flange comprises the two open ends. 
         [0013]    In general a through-bore is understood to mean a bore that passes completely through the workpiece. Thus, in the area of the flange the through-bore passes completely through the planetary bolt. 
         [0014]    The through-bore passes through the surface of the workpiece, the planetary bolt or the flange, at two points. These points are referred to as the open ends. The open ends are each bounded by a surrounding edge, which extends along the surface of the workpiece, the planetary bolt or the flange and along which the surface merges into the through-bore. Thus, the edge separates the surface from the through-bore. In particular, the edge is a boundary line between the surface and the through-bore. 
         [0015]    The flange is an area of the planetary bolt which, relative to the remainder of the planetary bolt, projects outward in the radial direction, i.e. perpendicularly to the axis of symmetry of at least part of the planetary bolt, the rotational axis of the planetary bearing and the rotational axis of a planetary gearwheel fitted onto the planetary bolt. In particular the flange can be an area of the planetary bolt that has at least one shoulder. The shoulder is a surface that extends at least partially radially, preferably radially. A surface extending at least partially radially is a surface that extends in a direction not parallel to the symmetry axis of at least part of the planetary bolt, the rotational axis of the planetary bearing and the rotational axis of a planetary gearwheel fitted onto the planetary bearing. The surface extends radially when it is perpendicular to the axes. 
         [0016]    The through-bore according to the invention passes through the shoulder, i.e. the shoulder contains one of the open ends. Thus, one of the open ends lies in the surface forming the shoulder. 
         [0017]    Preferably, the surface has two shoulders. In that case a first shoulder—as known from the prior art—serves for fixing the planetary bearing in the axial direction. The first shoulder is therefore in contact with an inner race of the planetary bearing, either directly or by way of an intermediate component inserted between the shoulder and the inner race. 
         [0018]    The second shoulder can be designed to come in contact with a corresponding surface of the planetary carrier that extends along the second shoulder, either directly or by way of an intermediate component inserted between the second shoulder and the surface of the planetary carrier. By virtue of the contact between the second shoulder and the surface of the planetary carrier, the planetary bolt is fixed in the axial direction. Thus, for the second shoulder the surface of the planetary carrier forms an abutment. In particular, for this purpose the surface of the planetary carrier extends along the second shoulder when the planetary bolt has been introduced into the planetary carrier. This also means that the surface of the planetary carrier extends radially or partially radially. 
         [0019]    Alternatively, there may be a gap between the second shoulder and the surface of the planetary carrier. 
         [0020]    Preferably—as known from the prior art—the planetary bolt comprises at least one cylindrical section. This section serves on the one hand to fix the planetary bolt in the planetary carrier, in particular by means of a press connection between a bolt seat in the planetary carrier and the cylindrical section. In addition the cylindrical section serves to receive the planetary bearing and fix it, especially in the radial direction. 
         [0021]    In this context cylindrical means that the section has the shape of a straight, circular cylinder. 
         [0022]    The flange is not part of the cylindrical section. Correspondingly, the flange is an area which, relative to the cylindrical section, projects outward in the radial direction. In the radial direction the flange extends outside the cylindrical section. 
         [0023]    The through-bore serves to enable the planetary bolt to be bolted onto the planetary carrier. For that purpose it is advantageous for the through-bore to extend axially, i.e. parallel to the symmetry axis of at least part of the planetary bolt, the rotational axis of the planetary bearing and the rotational axis of the planetary gearwheel fitted onto the planetary bearing. 
         [0024]    When the planetary bolt has been inserted in the planetary carrier, so that two bolt seats of the planetary carrier are holding the planetary bolt, a screw-bolt can be guided through the through-bore. The planetary carrier has an internal thread into which the screw-bolt can be screwed. For this, the internal thread and the through-bore are arranged coaxially with one another. In other words the internal thread and the through-bore are aligned. 
         [0025]    Furthermore, the planetary carrier forms an abutment for a head of the screw-bolt. This enables the screw-bolt to be tightened between the planetary bolt and the planetary carrier or the flange. In this way the first shoulder of the planetary bolt is braced against the inner race of one of the planetary bearings and, depending on the design, the second shoulder is braced against the surface of the planetary carrier extending along the second shoulder, in such manner that a defined axial play or a prestress of the planetary bearing is produced. In particular, this makes it possible to determine the axial play or the prestress before the press-fit connection between the bolt seats of the planetary carrier and the planetary bolt has been formed. 
         [0026]    Otherwise than in the solutions known from the prior art, the through-bore does not pass all the way through the entire planetary bolt, but only through the flange. This enables the use of shorter screw-bolts, which correspondingly have greater axial rigidity. Accordingly, axial displacements of the planetary bolt relative to the planetary carrier can be reliably prevented, even under high axial loads of the planetary bolt. The planetary bolt is screwed onto the lateral part on the generator side and there is therefore no structural weakening of the lateral part of the planetary carrier on the rotor side. A force acting on the rotor-side lateral part owing to the screw connection is also avoided. 
         [0027]    In a preferred further development, the flange is rotationally asymmetrical, i.e. not designed with rotational symmetry. Correspondingly, an area of the planetary carrier that receives the flange is also rotationally asymmetrical. This prevents the planetary bolt from twisting relative to the planetary carrier. Thus, a rotationally asymmetrically designed flange results in further improvement of the load-bearing capacity. 
         [0028]    Furthermore, it is preferable for the through-bore to be arranged eccentrically. This means that the axis of symmetry of the through-bore is different from the symmetry axis of at least part of the planetary bolt, the rotational axis of the planetary bearing and the rotational axis of the planetary gearwheel fitted onto the planetary bolt. Thus, the symmetry axis of the through-bore extends at distance, which is not vanishingly small or zero, away from the symmetry axis of at least part of the planetary bolt, the rotational axis of the planetary bearing and the rotational axis of the planetary gearwheel fitted onto the planetary bolt. The eccentric arrangement of the through-bore also prevents the planetary bolt from twisting relative to the planetary carrier. 
         [0029]    In another preferred further development, the planetary bolt is designed such that the flange has at least a first surface, a second surface and a third surface. The third surface connects the first and second surfaces. Thus, the third surface is between the first and second surfaces. 
         [0030]    The third surface has exactly two boundary lines. These in each case extend all round, forming closed figures. One of the boundary lines is at the same time a boundary line of the first surface. The other boundary line is at the same time the boundary line of the second surface. 
         [0031]    The third surface is the second shoulder. Correspondingly, one of the open ends of the through-bore is located in the third surface. 
         [0032]    At least the first surface is designed to form an interlocking connection in a press fit with one of the bolt seats of the planetary carrier. Preferably, the second surface too is designed to form an interlocking connection in a press fit with the bolt seat. Since the first and the second surfaces are both involved in the press connection, the load-bearing capacity of the press connection is increased still further. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]    An example embodiment described below is illustrated in the figures. In these, the same indexes denote the same, or functionally equivalent features. In detail, the figures show; 
           [0034]      FIG. 1 : A view of a planetary carrier, seen from above; 
           [0035]      FIG. 2 : A first sectioned view of the planetary carrier; and 
           [0036]      FIG. 3 : A second sectioned view of the planetary carrier. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]    The perspective view shown in  FIG. 1  is a view onto a planetary carrier  101  seen from a perspective in the axial direction. Into this planetary carrier  101  are inserted three planetary bolts  103 . In each case a planetary gearwheel  105  is mounted to rotate on the planetary bolts  103 . To fit the planetary gearwheels  105 , conical roller bearings  107  are used. 
         [0038]    The planetary bolts  103  each have a flange  109 . This is connected to the planetary carrier  101  by means of six screw-bolts  111 . 
         [0039]    As can be seen from  FIG. 1 , the flange  109  is asymmetrical. The flange  109  has a basic shape with a partially circular cross-section. Deviations from circularity are produced by flattened or recessed sections  113 . These make the flange  109  rotationally asymmetrical and thereby prevent the planetary bolt  103  from being able to twist relative to the planetary carrier  101 . 
         [0040]    The cross-section  2 - 2  indicated in  FIG. 1  is shown in  FIG. 2 . The cross-section  2 - 2  passes through the flattened and recessed sections  113 . Accordingly, the screw-bolts  101  cannot be seen in  FIG. 2 . It is clear that the recessed areas  113  are in direct contact with the planetary carrier  101 . This is important for the securing action against twisting described above. 
         [0041]    The planetary bearings  107  are conical roller bearings. These are fitted in the O-arrangement. An intermediate ring  201  is arranged between the inner races of the planetary bearings  107  and keeps them a distance apart from one another. The inner races of the planetary bearings  107  and the intermediate ring  201  are arranged between the shoulder  203  and a radially directed annular surface  205  of the planetary carrier  101  that extends around the planetary bolts  103 . Consequently, the shoulder  203  and the surface  205  fix the planetary bearings  107  and hence also the planetary gearwheels  105  in the axial direction. 
         [0042]    Between the planetary carrier  101  and the planetary bolt  103  a press-fit connection is formed, which fixes the planetary bolt  103  relative to the planetary carrier  101 , especially in the axial direction. Moreover, the planetary bolt  103  is fixed in the axial direction relative to the planetary carrier  101  by the screw-bolts  111 . This is made clear by the sectional view  3 - 3  indicated in  FIG. 1 . 
         [0043]    The sectional view  3 - 3  is shown in  FIG. 3 . Besides the shoulder  203  for fixing the planetary bearing  107  axially, the flange  109  of the planetary bolt  103  has a further shoulder  301 . This comes in contact with a corresponding surface of the planetary carrier  101  and thus fixes the planetary bolt  103  in an axial direction facing toward the planetary bearing  107 , i.e. the shoulder  301  blocks any displacement of the planetary bolt  103  in the axial direction toward the planetary bearing  107 . 
         [0044]    In an axial direction facing away from the planetary bearing  107 , the planetary bolt  103  is fixed by the screw-bolts  111 , i.e. the screw-bolts block any displacement of the planetary bolt  103  in the axial direction away from the planetary bearing  107 . 
         [0045]    Together with the shoulder  301 , the screw-bolts  111  prevent any axial displacement of the planetary bolt  103  relative to the planetary carrier  101 . The fixing of the planetary bolt  103  by the press-fit connection with the planetary carrier  101  on the one hand, and by the shoulder  301  and the screw-bolts  111  on the other hand, thus act in the same sense and reinforce one another. This improves the load-bearing capacity of the planetary bolt  103  in the axial direction. 
       INDEXES 
       [0000]    
       
           101  planetary carrier 
           103  Planetary bolt 
           105  Planetary gearwheel 
           107  Conical roller bearing 
           109  Flange 
           111  Screw-bolt 
           113  Recessed section 
           201  intermediate ring 
           203  Shoulder 
           205  Surface 
           301  Shoulder