Abstract:
The invention relates to a modular transmission system, comprising in at least one transmission stage with a housing a plurality of transmissions with different multiplications, each having a first transmission step comprising an annular gear with a pinion offset, said pinion off-set being identical for all transmissions of one transmission stage. The modular transmission system is provided with at least one first pinion of the angular gear with a first serrated crown gear in a crown gear serration and a second pinion with a second crown gear in a spiroplan gearing.

Description:
DESCRIPTION  
         [0001]    The invention relates to a modular transmission system such as is often employed in motive power engineering, in particular to adapt the rotational speed and the driving torque of an electric motor for a particular purpose, e.g. for use in a mechanical installation. Here the problem arises that depending on the intended application, a great variety of transmission ratios should be implemented with as little complexity as possible, by means of only a few specific motors (or even only a single motor).  
           [0002]    A transmission system of this kind is disclosed, for example, in the patent DE 197 33 546 C1. In that publication it is proposed to construct at least one gear module as an angular gear, which can be combined with a plurality of drive modules. The angular gear module is specified as a crown gear, the crown wheel of which is adapted to engage each of the output pinions of a drive motor. However, if it is desired to encompass very large ranges of transmission ratios, with the known transmission modules several gear housings must be provided, because crown gears customarily allow transmission ratios to vary merely within a range of about 1-6. The additional transmission stages (with spur wheels) proposed in that publication also allow only limited variation within a single housing.  
           [0003]    Another modular transmission system is known from the patent EP 0 557 961 B1. As input stage an axially offset angular gear is proposed, specifically a bevel gear, and as the subsequent additional transmission stages cylindrical gears are shown. The problem area associated with this system corresponds to that described above. In particular, it is also impossible here to cover a very large range of transmission ratios.  
           [0004]    The object of the present invention is to provide a modular transmission system that in a simple manner permits a large range of transmission ratios.  
           [0005]    This object is achieved by a modular transmission system according to claim  1 .  
           [0006]    By virtue of the invention, one and the same housing accommodates either a spiroplan transmission stage or a crown-gear transmission stage, while employing the same offset and the same bore. The particular advantage here is the large range of transmission ratios that results, because a spiroplan transmission stage and a crown-gear transmission stage enable transmission ratios to vary widely. The ratios for a crown-gear stage are about 1-6, while those for a spiroplan stage are 6-200. Overall, then, with this modular system a transmission-ratio range of 1-200 can be covered with only one transmission stage in a single housing.  
           [0007]    Regarding the spiroplan gearing, it should be noted that here the term is meant to denote gearings belonging to the category of angular gears. These are employed to transmit power between intersecting or crossing shafts. From a kinematic viewpoint, this is a spiral bevel gearing that resembles a worm-gear mechanism, except that unlike a worm gear, in this case a cylindrical worm meshes with a planar crown wheel as mating gear and not with a globoid worm wheel. The offset provided here is achieved by a curved longitudinal configuration of the teeth of the wheel.  
           [0008]    A spiroplan gearing is described, for example, in the applicant&#39;s patent DE 43 09 559.  
           [0009]    In contrast, the crown-gear arrangement (according to Niemann/Winter, Vol. III, Section 24.1.3) amounts kinematically to a pair of bevel gears in which the profile displacements change along the width of the teeth, in such a way that a cylindrical pinion and a planar crown wheel as mating wheel are produced. In the case of a straight-toothed pinion and axial offset the longitudinal tooth-flank shape of the wheel is a straight line, whereas with an oblique-toothed pinion it is curved.  
           [0010]    In particular, therefore, the proposed solution of the problem cited above is a modular transmission system with least one structural element, encased in a housing, that comprises a plurality of gearings with different transmission ratios, in each of which there is a first transmission stage that comprises an angular gear with axial offset incorporating an input drive pinion that meshes with a planar crown wheel having teeth that project parallel to the axis. In this system the axial offset is the same for all the transmission stages in a given structural element, and there are provided at least one first pinion with a first such planar crown wheel having a crown-gear tooth configuration and a second pinion with a second such planar crown wheel having a spiroplan tooth configuration.  
           [0011]    Preferably the housing also includes a second transmission stage that is rotationally connected to the input drive stage and that comprises at least two cylinder gears. This enables the range of transmission ratios to be expanded.  
           [0012]    In a first preferred embodiment the planar crown wheel in the first transmission stage is connected by way of a common bearing shaft to a pinion in the second transmission stage, so that the angular gear constitutes an input drive stage. Especially advantageous in this regard is the fact that when running rapidly, this transmission stage makes less noise than would be achievable with cylinder or bevel gears. Given that an angular stage is always more expensive than a cylinder-gear stage of the same size, a saving in expense is also obtained, because the site of action of the lower torque can be of smaller dimensions. A tooth-bearing adjustment like that for worm-gear or bevel-gear mechanisms is thus not needed here.  
           [0013]    In another embodiment of the invention an output wheel of the second transmission stage is connected to the input drive pinion of the first transmission stage, by way of a common bearing shaft, so that the angular gear forms an output-drive stage. The advantage of this arrangement lies in the fact that the cylinder gears already available in standard kits (in particular those supplied by the applicant) can be used, so that their transmission-ratio variability can be exploited economically. Nevertheless, by this means only two or three different transmission ratios of the output angular-gear stage (in particular spiroplan stage) are needed to provide a sufficient range of ratios. Here, again, the construction of the transmission system is simple and requires no tooth-bearing adjustment such as is required for worm- or conical-gear mechanisms. The result is an especially shock-absorbing and low-noise operation. Another important point in this regard is that the axial offset of the pinion makes room for the cylinder-gear transmission stage, so that the system as a whole can be of particularly flat construction.  
           [0014]    In particular in the embodiment in which the angular gear constitutes the output drive stage, it is advantageous for the housing to contain apparatus for flange-mounting a motor, such that the input-drive cylinder gear of the second stage is attached to an output shaft of the motor. This construction is especially economical and compact.  
           [0015]    Altogether, the axial offset preferably amounts to between {fraction (2/10)} and {fraction (4/10)} of the diameter of the planar crown wheel. 
       
    
    
       [0016]    In the following, preferred embodiments of the invention are described in greater detail with reference to the drawings, wherein  
         [0017]    [0017]FIG. 1 is a longitudinal section of a first preferred embodiment of the invention, in which a first stage of the transmission system comprises a pair of cylinder gears;  
         [0018]    [0018]FIG. 2 is a schematic sectional view of the transmission system shown in FIG. 1 along the line II-II;  
         [0019]    [0019]FIG. 3 is similar to FIG. 1 but of a second embodiment of the invention in which an input drive stage of the transmission system is an angular gear; and  
         [0020]    [0020]FIG. 4 is a section through the transmission system of FIG. 3 along the line IV-IV. 
     
    
       [0021]    In the following description, the same reference numerals are used for identical parts or parts with identical actions.  
         [0022]    As can be seen in FIGS. 1 and 2, a housing  10  is provided that comprises on one side a flange  11  for mounting an electric motor (not shown here), for the attachment of which bores  12 ,  13  are provided in the housing  10 . To make the interior of the housing accessible a cover  14  is provided, which is fixed firmly to the housing  10  by means of threaded bolts (not shown) and sealing devices. When a motor has been mounted on the housing, a cylindrical pinion  20  attached to a motor shaft  21  projects into the housing  10  through its open side next to the flange  11 . The cylindrical pinion  20  meshes with a cylinder gear  22  that is splined onto a first shaft  23 , which is supported in a bearing section  15  of the housing  10  by way of a first bearing  24  and a second bearing  25 . The first bearing  24  abuts with one outer surface against the cylinder gear  22  and with an inner surface against a spacer  26 , the other end of which contacts a first end face of the second bearing  25 . The second bearing  25  is attached between a shoulder  16  of the bearing section  15  and a retaining ring  27 , while the first shaft  23  is apposed by way of a shoulder  28  to the surface of the second bearing  25  that faces away from the cylinder gear  22 . In this way the shaft  23  is secured against axial displacement within the bearing section  15 .  
         [0023]    At its end opposite the cylinder gear  22  the first shaft  23  is provided with an angular-gear pinion  30 , the teeth of which mesh with those of a planar crown gear  31 . The latter can have teeth configured in either spiroplan form  32  or crown-wheel form  32 ′, depending on the desired transmission ratio. The shapes of the tooth flanks indicated in FIG. 1 are meant to illustrate this circumstance, in that the tooth-flank configuration labelled  32 ′ represents a crown-wheel gearing with straight-toothed pinion, whereas when an oblique-toothed pinion is used for a crown-wheel gearing, the tooth flanks would be curved. In both cases, i.e. both when the angular-gear pinion  30  and the planar crown wheel  31  are provided with a spiroplan tooth configuration  32  and when the two tooth configurations correspond to a crown-wheel gearing  32 ′, an offset a is provided between the axis of the shaft  23  and that of a second shaft  33  of the planar crown wheel  31 . That is, the only difference here is between the tooth geometries of the planar crown wheel  31  and the pinion  30 , the other components being identical; nevertheless, widely differing transmission ratios can be obtained (as is known per se) with these two tooth-flank shapes.  
         [0024]    The second shaft  33  of the planar crown wheel  31  is supported within the housing  10  by way of a third bearing  34  and a fourth bearing  35 . One outer surface of the third bearing  34  contacts a retaining ring  36  seated in the housing  10 . In the embodiment shown here a cover  37  is provided to cover the third bearing  34 . The third bearing  34  also makes contact with a first shoulder  38  of the shaft  33 , so that fixation of the shaft  33  in the axial direction (toward the left in FIG. 2) is ensured.  
         [0025]    The planar crown wheel  31  is apposed to a second shoulder  39  of the shaft  33  and is nonrotatably fixed to the shaft  33  by means of a spline  61 . On its side opposite the second shoulder  39  the planar crown wheel  31  makes contact with one side of the fourth bearing  35 , which on its other side rests against a retaining ring  36 ′ that is fixed within the housing  10 . As a result, the shaft  33  and the planar crown wheel  31  are secured against movement in the axial direction within the housing  10 , by means of the bearings  34  and  35 .  
         [0026]    The shaft  33  comprises an output drive stud  40 , which passes through a sealing ring  41  set into the housing  10 . A machine element that is to be driven can be splined onto the output stud  40 . As can readily be seen in FIG. 2, the shaft  33  can also be provided with two output drive studs if the cover  37  is removed and, instead, a second seal is provided at this end. An arrangement opposite to that shown in FIG. 2, in which the output drive stud  40  projects leftward and the cover  37  is seated on the right side, is of course also possible, because the housing  10  is symmetrically constructed in this respect.  
         [0027]    The embodiment of the invention shown in FIGS. 3 and 4 differs in principle from that in FIGS. 1 and 2 with respect to the order in which angular gear and cylinder gear are disposed. That is, in the embodiment shown in FIGS. 3 and 4 an input drive shaft  42  is provided that comprises a drive stud  43  projecting out of the housing  10 , onto which a driving element can be splined. The input drive shaft  42  is sealed to the housing  10  by a sealing ring  44  and is supported by an outer bearing  46  and an inner bearing  47 . The outer bearing  46  is seated between a shoulder in the housing  10  and a retaining ring  45  and abuts against a first shoulder  48  on the input drive shaft  42 . The inner bearing  47  is apposed to a second shoulder  49  of the input drive shaft  42  and on the other side, to a shoulder of the housing  10 . In this way the input drive shaft  42  is fixed within the housing  10  so that it cannot be moved in the axial direction.  
         [0028]    At its other end, opposite the drive stud  43 , the input drive shaft  42  is provided with the angular-gear pinion  30 , which—depending on the particular embodiment—can have a spiroplan or a crown-wheel tooth configuration, as explained above. The angular-gear pinion  30  meshes with the teeth  32  or  32 ′ of the planar crown gear  31 , which is seated on a shaft  51  to which is also fixed a first cylinder gear  50 ; hence the cylinder gear  50  and the planar crown wheel  31  are connected so that they cannot rotate with respect to one another.  
         [0029]    The first cylinder gear  50  meshes with a second cylinder gear  52 , which is nonrotatably fixed to a drive shaft  53  by means of a spline  61 . The drive shaft  53  is constructed as a hollow shaft, throughout which runs a longitudinal groove  53 ′ that can be used to spline into place an element that is to be driven. The drive shaft  53  is seated in the housing by way of a first bearing  54  and a second bearing  55 . At its outer surface the first bearing  54  makes contact with a retaining ring  56  that is seated in the housing  10 . On its other side, the first bearing is apposed to a spacer  62  which in turn is apposed to the second cylinder gear  52 . The second cylinder gear  52  rests against a shoulder  63  of the drive shaft  53 .  
         [0030]    The second bearing  55  contacts with its outer surface a second retaining ring  57  seated in the housing  10 . On its other side the second bearing  55  makes contact with a shoulder  60  of the drive shaft  53 , so that the drive shaft  53  and the second cylinder gear  52  mounted thereon are secured against axial displacement. For sealing the drive shaft  53 , at its two ends seals  58  and  59  are provided.  
         [0031]    The exemplary embodiments of the invention described above each display individual elements that are interchangeable between the two embodiments. In particular, for example, it is possible in the second embodiment of the invention, shown in FIGS. 3 and 4, also to dispose the angular-gear pinion  30  directly on the shaft of an input drive motor and to provide the housing  10  with a flange  11  and bores  12 ,  13  for direct flange-mounting of the motor, as is shown in FIGS. 1 and 2. It is likewise possible in the embodiment according to FIGS. 1 and 2 to replace the flange  11  and the attachment bores  12 ,  13  by the input drive shaft  42  shown in FIGS. 3 and 4, with its bearing in the housing and the drive stud  43  for connection to external apparatus as desired.  
         [0032]    Furthermore, the construction of the drive shaft  53  as a hollow shaft as shown in FIGS. 3 and 4 can be applied in the embodiment according to FIGS. 1 and 2 and, conversely, the unilateral arrangement of the drive shaft according to FIGS. 1 and 2 is applicable in the embodiment according to FIGS. 3 and 4. As a result, a modular transmission system with extreme versatility is created. In particular the cylinder-gear transmission stages can be composed of cylinder gears such as are provided in the cylinder-gear transmission modules that are already widely available, so that a broad palette of transmission ratios can be implemented at low cost. Because the angular gear can be employed with either a spiroplan or a crown-wheel tooth configuration, the range of transmission ratios becomes extremely broad.  
       List of reference numerals  
       [0033]    [0033] 10  Housing  
         [0034]    [0034] 11  Flange  
         [0035]    [0035] 12  Bore  
         [0036]    [0036] 13  Bore  
         [0037]    [0037] 14  Cover  
         [0038]    [0038] 15  Bearing section  
         [0039]    [0039] 16  Shoulder  
         [0040]    [0040] 20  Cylindrical pinion  
         [0041]    [0041] 21  Motor shaft  
         [0042]    [0042] 22  Cylinder gear  
         [0043]    [0043] 23  First shaft  
         [0044]    [0044] 24  First bearing  
         [0045]    [0045] 25  Second bearing  
         [0046]    [0046] 26  Spacer  
         [0047]    [0047] 27  Retaining ring  
         [0048]    [0048] 28  Shoulder  
         [0049]    [0049] 30  Angular-gear pinion  
         [0050]    [0050] 31  Planar crown wheel  
         [0051]    [0051] 32  Spiroplan tooth configuration  
         [0052]    [0052] 32 ′ Crown-wheel tooth configuration  
         [0053]    [0053] 33  Second shaft  
         [0054]    [0054] 34  Third bearing  
         [0055]    [0055] 35  Fourth bearing  
         [0056]    [0056] 36  Retaining ring  
         [0057]    [0057] 36 ′ Retaining ring  
         [0058]    [0058] 37  Cover  
         [0059]    [0059] 38  First shoulder  
         [0060]    [0060] 39  Second shoulder  
         [0061]    [0061] 40  Output drive stud  
         [0062]    [0062] 41  Sealing ring  
         [0063]    [0063] 42  Input drive shaft  
         [0064]    [0064] 43  Input drive stud  
         [0065]    [0065] 44  Sealing ring  
         [0066]    [0066] 45  Retaining ring  
         [0067]    [0067] 46  Outer bearing  
         [0068]    [0068] 47  Inner bearing  
         [0069]    [0069] 48  First shoulder  
         [0070]    [0070] 49  Second shoulder  
         [0071]    [0071] 50  First cylinder gear  
         [0072]    [0072] 51  Shaft  
         [0073]    [0073] 52  Second cylinder gear  
         [0074]    [0074] 53  Output drive shaft  
         [0075]    [0075] 53 ′ Groove  
         [0076]    [0076] 54  First bearing  
         [0077]    [0077] 55  Second bearing  
         [0078]    [0078] 56  First retaining ring  
         [0079]    [0079] 57  Second retaining ring  
         [0080]    [0080] 58  First seal  
         [0081]    [0081] 59  Second seal  
         [0082]    [0082] 60  Shoulder  
         [0083]    [0083] 61  Spline  
         [0084]    [0084] 62  Spacer  
         [0085]    [0085] 63  Shoulder