Patent Publication Number: US-2022228643-A1

Title: Segmented vibration absorber

Description:
CROSS-REFERENCE TO PRIOR APPLICATIONS 
     This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2020/055772, filed on Mar. 5, 2020, and claims benefit to German Patent Application No. DE 10 2019 207 826.5, filed on May 28, 2019. The International Application was published in German on Dec. 3, 2020 as WO 2020/239279 under PCT Article 21(2). 
    
    
     FIELD 
     The present disclosure relates to a vibration absorber for securely fixing to the housing of a gearbox. 
     BACKGROUND 
     Vibration absorbers are used in wind turbines to reduce gearbox vibrations. Vibrations are associated with mechanical loads and can therefore lead to gearbox damage. If the frequencies of the vibrations are within the audible range, undesirable noise emissions occur. 
     If the problems described emerge first in operation, it is not possible to retrofit conventional vibration absorbers. Nor is it possible to subsequently adapt conventional vibration absorbers to the vibrations that occur. 
     SUMMARY 
     In an embodiment, the present disclosure provides a vibration absorber for securely fixing to the housing of a gearbox. The vibration absorber includes an absorber mass having a first group of segments that are rotationally symmetrical to one another with respect to a rotational axis and/or central axis of the gearbox. The segments can be rigidly connected to one another. The vibration absorber can further include connectors that are rigidly connected to two segments each. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following: 
         FIG. 1  shows a segmented absorber mass; 
         FIG. 2  shows the fixing of a segment; and 
         FIG. 3  shows an absorber mass with axially offset segments. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure provides a vibration absorber with improved properties in comparison to solutions known from the prior art. In particular, it should be possible to retrofit the vibration absorber and adapt it flexibly to the vibrations that occur. 
     The vibration absorber is designed to be fixed securely to the housing of a gearbox or to a component of the gearbox. The component is preferably a gearbox housing or a component fixed securely to the housing, i.e., a component that is rigidly fixed in the gearbox housing, i.e., without the possibility of a relative movement. 
     A vibration absorber is a vibration damper, the mass or absorber mass of which is elastically fixed to one or more components that are rigidly connected to one another, i.e., without the possibility of a relative movement. A vibration absorber generally has an absorber mass and one or more elastic suspensions. By means of the suspensions, the absorber mass is fixed in a component whose vibrations are to be damped. 
     In the present case, the absorber mass is fixed to the component of the gearbox by means of the elastic suspensions. The elastic suspensions can be elastomer bushings, for example. The bushings are each fixed in a hole in the absorber mass and screwed to the gearbox. 
     The absorber mass has a first group of segments. Segments denote parts of the absorber mass that are physically separated from one another. Two each of the segments are not integrally connected to one another. 
     The segments of the first group are rotationally symmetrical to one another with respect to a rotational axis and/or central axis of the gearbox. This means that the segments of the first group can be mapped onto one another by rotation about the rotational axis and/or central axis by at least one angle that is less than 360°. 
     The segments of the first group are preferably not rotationally symmetrical to the rotational axis and/or central axis. This implies that the set of angles of mappings that map the segments onto one another is discrete. 
     The segments can preferably be mapped onto one another by rotation exclusively by angles that are 360°/n or an integer multiple of 360°/n, wherein n denotes the number of segments. This implies that the segments or in each case two segments are identical in design. 
     The aforementioned rotational axis is the rotational axis of a rotatable component of the gearbox. It can be, for example, the rotational axis of a gearwheel, a shaft, or a planetary carrier. 
     The aforementioned central axis is a straight line on which at least two center points of a component of the gearbox, such as a ring gear, are located. The term “center point” refers to a geometric center of gravity of the component in a sectional plane that is directed orthogonally to the straight line. 
     The segmentation of the absorber mass makes it possible to attach the absorber mass to the gearbox at a later date. Each individual segment is also easier to handle during assembly than a conventional, unsegmented absorber mass. 
     In a preferred development, the segments are connected to one another rigidly, i.e., without the possibility of a relative movement. As a result of the rigid connection, the segments work together as a single absorber mass. 
     In a preferred development, the rigid connection between two segments each is produced by connecting means which extend between the segments and bridge a gap between the segments. This means that the connecting means are in each case rigidly connected to two segments. 
     In a preferred development, the segments are structurally identical. Two segments each are thus structurally identical. 
     In general, two components are structurally identical if they coincide in their physical parameters, in particular with regard to their material and geometry properties, within the scope of the production tolerances occurring. 
     In a preferred development, the absorber mass has a second group of segments. The segments of the second group have the same features as the segments of the first group. The above statements therefore apply mutatis mutandis to the segments of the second group. In particular, the segments of the second group are rotationally symmetrically, preferably rigidly, connected to one another with respect to the aforementioned rotational axis and/or central axis, wherein in each case, a connecting means preferably rigidly connects two segments of the second group to one another, and preferably structurally identically. 
     According to the development, the first group and the second group or the segments of the first group and the segments of the second group are arranged so as to be axially offset from one another. This means that a plane oriented orthogonally to the aforementioned rotational axis and/or central axis runs between the segments of the first group and the segments of the second group. 
     The development makes it possible to modify the size of the absorber mass. In particular, the size of the absorber mass can be adapted to the vibrations occurring during operation. 
     In a preferred development, a segment of the first group and a segment of the second group are in each case rigidly connected to one another. As a result, the segments of the first group and of the second group form a single absorber mass. 
     In a further preferred development, a segment of the first group and a segment of the second group are in each case structurally identical. The absorber mass thus consists of structurally identical segments. The structurally identical segments reduce variant-related costs. 
     The vibration absorber is preferably part of a gearbox that additionally has a ring gear. The ring gear can, for example, be part of a planetary stage, which also has one or more planetary gears, a planetary carrier, and a sun gear. The planetary gears are rotatably mounted in the planetary carrier and mesh with the ring gear and/or the sun gear. At least two of the three components sun gear, planetary carrier, and ring gear are rotatably mounted about a common rotational axis. The third component is preferably fixed securely to the housing. The rotational axis about which the at least two components are rotatably mounted is preferably the rotational axis mentioned at the outset. 
     According to the development, the vibration absorber is fixed to the ring gear. As described above, this fixing is elastic and is preferably implemented by means of elastomer bushings. 
     In a preferred development, the ring gear is screwed or joined to a housing of the gearbox by means of one or more screws or dowel pins. According to a development, the screws or dowel pins also serve to fix the vibration absorber. The vibration absorber is thus screwed or joined to the ring gear with the same screws or dowel pins with which the ring gear is screwed or joined to the housing. 
     This development makes it possible to also retrofit a vibration absorber to gearboxes that are structurally not intended to accommodate a vibration absorber. In addition, the use of existing screws is cost-effective. 
     Preferred exemplary embodiments are shown in the figures. Here, matching reference numbers indicate identical or functionally identical features. 
     The absorber mass  101  shown in  FIG. 1  has four identical segments  103   a ,  103   b ,  103   c ,  103   d . The segments  103   a ,  103   b ,  103   c ,  103   d  are arranged rotationally symmetrically. They can be mapped onto one another by rotating them by an angle of 90°. 
     Arranged between two segments  103   a ,  103   b ,  103   c ,  103   d  each is a connecting plate  105   a ,  105   b ,  105   c ,  105   d , which rigidly connects the segments  103   a ,  103   b ,  103   c ,  103   d  to one another. The connecting plate  105   a  connects the segments  103   a ,  103   b  to one another, the connecting plate  105   b  connects the segments  103   b ,  103   c , the connecting plate  105   c  connects the segments  103   c ,  103   d , and the connecting plate  105   d  connects the segments  103   d ,  103   a . The connecting plates  105   a ,  105   b ,  105   c ,  105   d  are screwed to the respective segments  103   a ,  103   b ,  103   c ,  103   d.    
     For fixing in a gearbox, the segments  103   a ,  103   b ,  103   c ,  103   d  have holes  107 . In the exemplary embodiments shown in the figures, there are four holes  107  per segment  103   a ,  103   b ,  103   c ,  103   d . The fixing in the gearbox is illustrated in  FIG. 2  in detail. 
       FIG. 2  shows a segment  103   a  with its holes  107 . The holes are arranged in a circle around the same axis to which the segments  103   a ,  103   b ,  103   c ,  103   d  are rotationally symmetrical. Screws  201  project into the holes  107 . These are the screws by which a ring gear is screwed to a gearbox housing. 
     Elastomer bushings are fixed in the holes  107 . They are not omitted in  FIG. 2  for the sake of better illustration. The elastomer bushings in turn are screwed with the screws  201 . In this way, an elastic connection is established between the ring gear and the segment  103   a.    
     The remaining segments  103   b ,  103   c ,  103   d  are fixed in the ring gear in the same way. 
     As shown in  FIG. 3 , each segment  103   a ,  103   b ,  103   c ,  103   d  forms a segment package  301   a ,  301   b ,  301   c ,  301   d  with further segments. The segments of each segment package  301   a ,  301   b ,  301   c ,  301   d  are arranged so as to be axially offset from one another. As a result, the respective holes  107  of the segments  103   a ,  103   b ,  103   c ,  103   d  are aligned. 
     The holes aligned with one another accommodate one elastomer bushing each. In the present case, each segment package  301   a ,  301   b ,  301   c ,  301   d  is thus fixed in the ring gear by four bushings. Two segments each of adjacent segment packages  301   a ,  301   b ,  301   c ,  301   d  are fixed in one another by means of connecting plates (not shown in  FIG. 3 ). 
     While subject matter of the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any statement made herein characterizing the invention is also to be considered illustrative or exemplary and not restrictive as the invention is defined by the claims. It will be understood that changes and modifications may be made, by those of ordinary skill in the art, within the scope of the following claims, which may include any combination of features from different embodiments described above. 
     The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C. 
     REFERENCE SIGNS 
     
         
         
           
               101  Absorber mass 
               103   a  Segment 
               103   b  Segment 
               103   c  Segment 
               103   d  Segment 
               105   a  Connecting plate 
               105   b  Connecting plate 
               105   c  Connecting plate 
               105   d  Connecting plate 
               107  Hole 
               201  Screw 
               301   a  Segment package 
               301   b  Segment package 
               301   c  Segment package 
               301   d  Segment package