Abstract:
A planetary gear ( 1 ) such as a differential gear, with a planetary carrier ( 3 ) on which planetary wheels ( 5, 6 ) are rotatively connected, with at least one sun gear ( 9, 10, 11 ) in meshing engagement, whereby the planetary carrier ( 3 ) can be connected to a drive wheel ( 15 ) such as a spur wheel ( 16 ), whereby further comprising a rolling bearing ( 20 ) having an inner bearing ring ( 29 ) and an outer bearing ring ( 28 ) for the axial and/or radial positioning of the planetary carrier ( 3 ) with respect to a fixed housing such as a gear housing, characterized in that an outer bearing ring ( 28 ) between the inner bearing ring ( 29 ) and the planetary support ( 3 ) is forced as far as a seating region radially inwards of the planetary carrier ( 3 ) for connection to the planetary carrier ( 3 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is filed under 35 U.S.C. §120 and §365(c) as a continuation of International Patent Application PCT/EP2013/056518, filed Mar. 27, 2013, which application claims priority from German Patent Application No. DE102012206440.0, filed Apr. 19, 2012, which applications are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a planetary gear such as a differential gear comprising a planetary carrier, to which planetary wheels that mesh with at least one sun gear are rotatively attached, whereby said planetary carrier is connected to a drive wheel, such as a spur wheel, and whereby further a bearing, such as a rolling bearing, is provided with two bearing rings, such as an inner bearing ring and an outer bearing ring for the axial and/or radial positioning of the planetary carrier with respect to a fixed housing such as a gear housing. The planetary carrier may also be referred to as a cage that, in particular, may be designed as a differential cage. 
       BACKGROUND OF THE INVENTION 
       [0003]    Different planetary gears are already known from the prior art, for example from EP 0156067. 
         [0004]    In principle, differential gears for automotive vehicles are known from DE 10156890 C1. A differential gear is disclosed for an automotive vehicle with a differential housing having a drive sprocket supported in a housing wall, in which a differential bolt is arranged with at least a rotatively mounted differential pinion that engages with a drive gear of a drive shaft mounted in the differential housing. The drive shaft is supported by at least a first bearing in the housing wall of the differential gear and/or the differential housing by means of at least one second bearing for the drive shaft, while the drive shaft has a common bearing bush for the first bearing serving as a shaft bearing of the drive shaft and the housing bearing of the differential housing. 
         [0005]    A differential arrangement engaging with bevel gears is also known from U.S. Pat. No. 7,775,928. 
         [0006]    Furthermore, a gear arrangement that engages with planetary wheels is known from DE 10 2009 017 397 A1. The gear arrangement introduced there relates to a differential gear with a drive-side wheel member, a first drive wheel that is rotatively fixed to a first driven axle, while a second drive wheel is rotatively fixed to a second driven axle, whereby between the first drive wheel and the second drive wheel, a gear assembly is provided for transmitting torque from the drive side wheel member to the first drive wheel and second drive wheel. The first drive wheel member in this case has the form of a first drive wheel with a bulge that is radially spaced from the first drive axle. The second drive member further has the form of a second drive wheel extending radially outwards from the second drive axle. Further, the bulge extends further away from the second drive wheel. The gear assembly is disposed in a space formed by the protrusion of the first drive wheel and the opposite region of the space formed by the second drive wheel. 
         [0007]    Such planetary gears, which are designed as differential gears, may be formed as spur wheel differential gears as they are known, for example, from WO 2010/112366 A1. The spur wheel differential gear arrangement presented there, discloses the operational capability in an automotive vehicle. In this case, each toothed helical sun gear, planetary wheel and a hollow wheel are supported by a surrounding housing with bearings, so that the parallel sun gears are each coupled with parallel drive shafts. It is disclosed in this publication that frictional surfaces are disposed between the parallel sun gears and/or between the sun gears and the surrounding housing. 
         [0008]    However, these known planetary gears have the disadvantage that they require a lot of axial space. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    It is the object of the present invention to remedy this situation and to create a space-saving, especially axial space-saving improvement, which is both long-lasting and is at least cost-neutral, or is able in the optimal case to reduce costs. 
         [0010]    According to the invention, this task is solved by forcing an outer bearing ring between the inner bearing ring and the planetary carrier as far as a seating region located radially inside the planetary carrier for connection to the planetary carrier. 
         [0011]    The bearing diameter of the rolling bearing for supporting the planetary carrier, also referred to as a differential cage, may be enlarged, whereby the outer bearing ring of the rolling bearing is drawn radially and laterally in the direction of a central axis of the differential to the inner bearing ring. The differential cage is suspended from the outer bearing ring, so that, differing from the standard approach where the outer bearing diameter of the housing seat, i.e., the seat of the differential cage, is always larger than the shaft seat, the outside diameter of the housing seat may now be made smaller than the shaft seat. 
         [0012]    It is of advantage when the inner bearing ring is swaged. Costs can then be reduced and the life increased. 
         [0013]    It is also advantageous when the inner bearing ring has an axially protruding collar portion which can be brought into contact with the sun gear. The inner bearing ring can then be simultaneously used for the centering of the sun gear. 
         [0014]    The forces may be further optimized if the planetary carrier has an axially extending collar portion which can be brought into contact with the sun gear. A variant is also disclosed where the two collar portions of the planetary carrier and the inner bearing ring, respectively, are parallel to one another, whereby one of the two collar portions protrudes axially over the other in the direction of the sun gear. However, a flush arrangement is also conceivable. According to the application, the forces may then be absorbed optimally. 
         [0015]    It is also advisable when the outer bearing ring is formed as a one piece cold formed part with a raceway for the rolling elements. 
         [0016]    An advantageous embodiment is also disclosed wherein the planetary carrier extends radially further inwards than the inner raceway. 
         [0017]    In order to achieve advantageous sealing and support effects, it is advantageous if a cover is arranged in the radial position of the planetary carrier and/or the inner bearing ring, which preferably has a U-shaped profile surrounding a hole. 
         [0018]    It is also advantageous if the planetary gear is formed as a spur wheel differential comprising two sun gears, each of which is in meshing engagement with at least one planetary wheel of a planetary wheel set. It is then possible to achieve a particularly compact planetary gear design construction that is simultaneously highly resilient and cost-effective. It should also be noted that the two planetary wheels of a planetary wheel set are each to be brought into meshing engagement. 
         [0019]    In order to achieve a positive self-limiting effect, it is also advantageous if a friction disc is located between the sun gears. 
         [0020]    It is further advantageous if the outer bearing ring is connected material-wise, shape-wise and/or force-fitting-wise to the planetary carrier. 
         [0021]    It is also advantageous if a connection part that connects the planetary carrier to the rolling bearing is deep-drawn and manufactured. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    Additional features, advantages, and effects of the invention are discernible from a preferred exemplary embodiment of the invention as well as the attached drawings, wherein: 
           [0023]      FIG. 1  shows a planetary gear in a longitudinal sectional view; 
           [0024]      FIG. 2  shows a further illustration of the planetary gear in a longitudinal section; 
           [0025]      FIG. 3  shows a further longitudinal section of the planetary gear; 
           [0026]      FIG. 4  shows a further longitudinal section of the planetary gear; 
           [0027]      FIG. 5  shows a further longitudinal section of the planetary gear; 
           [0028]      FIG. 6  shows a further longitudinal section of the planetary gear; 
           [0029]      FIG. 7  shows a special planetary gear; 
           [0030]      FIG. 8  shows a further planetary gear, which is also shown in the variants of  FIGS. 6 and 7  in longitudinal section; 
           [0031]      FIG. 9  shows a first embodiment of a planetary gear; 
           [0032]      FIG. 10  shows a special caulked planetary gear configuration; and, 
           [0033]      FIG. 11  shows a diagonally shaped connecting part construction in the region of the bearing with raceways of a further embodiment of a planetary gear. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    A first specific form of a planetary gear  1  is shown in  FIG. 1 . The planetary gear  1  is designed as a differential gear, in particular as a spur wheel differential gear  2 . It includes a planetary carrier  3 , which may be referred to as a cage, in particular a differential cage. The planetary carrier  3  may also be referred to as a planetary wheel carrier. 
         [0035]    The planetary wheel sets  4 , each of which has a first planetary wheel  5  and a second planetary wheel  6 , are supported on the planetary carriers  3  by respective bolts  7  that are located in bearing sleeves  8 . The planetary wheels  5  and  6  are connected in operative contact with sun gear  9 . In this case, first planetary wheel  5  meshes in operative engagement with first sun gear  10 , while the second planetary wheel  6  meshes in operative engagement with second sun gear  11 . Bolt  7  is designed as a hollow bolt. The two planetary wheels  5  and  6  of planetary wheel set  4  can be meshed together in operative engagement. 
         [0036]    Advantageously, three, four, five, six or seven planetary wheel sets  4  are used, each having first planetary wheel  5  and second planetary wheel  6 . 
         [0037]    The planetary carrier  3  has first half  12  and second half  13  which are connected via connecting element  14  such as a rivet to drive wheel  15  which is designed as spur wheel  16 . Spur wheel  16  has externally angled teeth  17 . 
         [0038]    Planetary carrier  3  is connected via separate connection part  18  with bearing  19 , which is formed as rolling bearing  20 . Rolling bearing  20  is designed as an angular contact ball bearing. Angular contact ball bearings are respectively located in both first half  12  of planetary carrier  3  and second half  13  of planetary carrier  3 . Tapered roller bearings are also possible. 
         [0039]    In this case, connection part  18  has first flange portion  21 , which is connected via connecting portion  22  with second flange portion  23 . In this case, first flange portion  21  forms first interface  24 , which is in contact with inner surface  25  of planetary carrier  3 . Second flange portion  23  also forms second interface  26  which is in contact with outer surface  27  of bearing  19 . In this case, second interface  26  is applied to outer ring  28  of rolling bearing  20 . 
         [0040]    However, it is possible that, as shown in  FIG. 2 , inner ring  29  of rolling bearing  20  lies against second interface  26  with an inwardly facing surface of inner ring  30 . 
         [0041]    While in the version shown in  FIG. 1 , only a certain region of connecting portion  25  lies radially against planetary carrier  3 , in the version shown in  FIG. 2 , all or nearly all of connecting portion  22  extending axially in the radial direction, lies against planetary carrier  3 . Connection part  18  is formed as a sheet metal part, especially as a sheet-metal sleeve. 
         [0042]    While in the version shown in  FIG. 1 , both planetary carrier  3  as well as connection part  18  form collar  31 , while in the version according to  FIG. 1 , planetary support  3  with collar portion  32  lies against first sun gear  10 , while connection part  18  with collar portion  33  lies against first sun gear  10 , but in the version of  FIG. 2 , only collar portion  33  of connection part  18  lies against sun gear  9 . 
         [0043]    As also shown in  FIG. 2 , external teeth, like sprocket wheel  34  are provided at least on one of sun gears  9 . 
         [0044]    In the gear according to  FIG. 7 , connection part  18  is formed like pot-like cover  35 , which is configured with thin walls when compared with the planetary carrier, particularly only half of the wall thickness, or, advantageously, only one third to one quarter of the wall thickness of planetary carrier  3 . Friction disc  37  is located in recess  36  that is in contact with sun gear  9 , in particular first sun gear  10  or second sun gear  11 . 
         [0045]    Cover  35  has axially extending outer surface  38  which is at the same height measured in a radial direction and is in contact with both planetary carrier  3  as well as inner ring  29 , in particular inner surface  30  of inner ring  29 . 
         [0046]    As can be seen in  FIG. 10 , caulking  39  is mounted axially spaced from sun gear  9  region of the bearing. On the left side of spur wheel differential gear  2 , it can also be seen that at outer ring  28  of rolling bearing  20  constructed as a tapered roller bearing, second flange portion  23  is obliquely and/or transversely oriented relative to the radial direction and obliquely and/or transversely relative to the axial direction. 
         [0047]    In the version according to  FIG. 4 , inner ring  29  is formed as extruded inner ring  29 , whereas outer ring  28  is formed as a drawn outer bearing ring. In this way, the raceway characteristics are improved and the centering of the spur wheel differential ensured. 
         [0048]    Returning to  FIG. 1 , it should be emphasized again that collar  31  is axially oriented, while two collar portions  32  and  33  are angled perpendicularly to planetary carrier  3  and connection part  18  with its connecting portion  22 . In the gear according to  FIG. 1 , collar portions  32  and  33  have the same axial extension or axial length and both are in contact in with respective sun gear  10  or  11 . Collar portions  32  and  33  are hardened, especially through-hardened. However, it is possible that in place of separate connecting members  18 , one of the two bearing rings, i.e., outer bearing ring  28  or inner bearing ring  29 , is so remodeled that it forms both first flange portion  21  as well as the respective raceway for rolling body  40 . 
         [0049]    In the gear according to  FIG. 2 , unlike in the gear according to  FIG. 1 , inner bearing ring  29  is connected with first half  12  of planetary carrier  3  via separate connection part  18 . Connection part  18  is then applied to two surfaces of planetary carrier half  12 . However, collar portion  33  of connection part  18  remains axially above collar portion  32  of planetary carrier  3  and, unlike collar portion  32 , is in contact with first sun gear  10 . 
         [0050]    In the gear according to  FIGS. 3 to 5 , separate connection part  18  is dispensed with and inner bearing ring  29  has also collar portion  33 . While planetary carrier  3  in  FIG. 3  itself also has collar portion  32 , this is missing in the gears of  FIGS. 4 and 5 . In fact, in the gear of  FIG. 4 , there is friction disc  37  between inner bearing ring  29  and sun gear  10 . Further, in the gear according to  FIG. 5  on the side of planetary carrier  3  facing sun gear  10 , there is projection  41 , while on the bearing-facing side there is recess  42  whereby collar portion  33  of inner bearing ring  29  at least partially fills recess  42 . Projection  41  then forms an axial stop for inner bearing ring  29 . In principle, inner bearing ring  29  may be connected via a frictional and/or positive connection, in particular using an interference fit with planetary carrier  3 . Axis of rotation  43  of planetary carrier  3  is simultaneously the rotational axis of sun gear  9  and the axis of symmetry of these components. 
         [0051]    In the gear according to  FIG. 6 , the cover is thin-walled and is formed as a ring with a U-shaped cross-section. Unlike in the gear of  FIG. 7 , no additional recess is provided for friction disc  37 . It should be noted that the rolling bodies used in bearing  19  are provided with reference numeral  40  and may generally be formed as balls, tapered rollers, needles or similar components. In particular, angular contact ball bearings and tapered roller bearings have proven to be sufficiently durable and inexpensive. 
         [0052]    The gear according to  FIG. 8  differs from the gear of  FIG. 7  basically in the fact that inner bearing ring  29  is not brought into contact with planetary carrier  3  as cover  35  is interposed as a force-transmitting element. On outer surface  38  of cover  35 , there thus sits both planetary carrier  3  with one or both halves  10  and  11  in a frictional and/or form-fitting manner as well as inner bearing ring  29 . A modification is possible whereby, instead of inner bearing ring  29 , outer bearing ring  28  is seated on the outer surface of cover  35 . 
         [0053]    In  FIG. 9  separate connection part  18  is, in turn, dispensed with and, by means of a modification of the first gear, the outer bearing ring, which is formed as a drawn outer bearing ring, is provided with an undulating outer shape. 
         [0054]    While, as stated above regarding the gear of  FIG. 10 , connection part  18  is straight, i.e., has axially-oriented first and second flange portions  21  and  23  as shown in the gear according to  FIG. 11 , the second flange is also oriented obliquely to axis of rotation  43  and to the perpendicular radial direction extending there. Inner bearing ring  29  may be swaged. 
         [0055]    The recessed hole through the circumferential profile contains axis of rotation  43 . 
       LIST OF REFERENCE NUMBERS 
       [0056]      1  Planetary gear 
         [0057]      2  Spur wheel differential gear 
         [0058]      3  Planetary carrier 
         [0059]      4  Planetary wheel set 
         [0060]      5  First planetary wheel 
         [0061]      6  Second planetary wheel 
         [0062]      7  Bolts 
         [0063]      8  Bearing rings 
         [0064]      9  Sun gear 
         [0065]      10  First sun gear 
         [0066]      11  Second sun gear 
         [0067]      12  First half 
         [0068]      13  Second half 
         [0069]      14  Connecting element 
         [0070]      15  Drive wheel 
         [0071]      16  Spur wheel 
         [0072]      17  Externally inclined teeth 
         [0073]      18  Connection part 
         [0074]      19  Bearing 
         [0075]      20  Rolling bearing 
         [0076]      21  First flange portion 
         [0077]      22  Connecting portion 
         [0078]      23  Second flange portion 
         [0079]      24  First interface 
         [0080]      25  Inner surface 
         [0081]      26  Second interface 
         [0082]      27  Outer surface 
         [0083]      28  Outer bearing ring 
         [0084]      29  Inner bearing ring 
         [0085]      30  Inner ring surface 
         [0086]      31  Collar 
         [0087]      32  Collar portion of the planetary carrier 
         [0088]      33  Collar portion of the connection part 
         [0089]      34  Sprocket 
         [0090]      35  Cover 
         [0091]      36  Recess 
         [0092]      37  Friction disc 
         [0093]      38  Outer surface 
         [0094]      39  Caulking 
         [0095]      40  Rolling bodies 
         [0096]      41  Projection 
         [0097]      42  Recess 
         [0098]      43  Axis of rotation