Abstract:
The invention relates to a toothed wheel ( 4 ) for mounting in a toothed gearing ( 1 ), wherein the toothed wheel ( 4 ) and a cylindrical gear ( 8 ) form a gear pair. The toothed wheel ( 4 ) has a curved pitch surface ( 5 ) with teeth, which comprises at least one tooth ( 7 ) extending spirally. The toothed wheel ( 4 ) is configured for mounting in the gear pair in such a way that the axis ( 2 ) of the toothed wheel ( 4 ) extends substantially perpendicular relative to the axis of the cylindrical gear ( 8 ).

Description:
[0001]    The present invention relates to a gearwheel having a curved pitch surface and a gear having such a gearwheel. The gear preferably includes a pair of gears having a gearwheel with a toroidal, curved pitch surface and having a gearwheel with cylindrical external teeth.  
         RELATED ART  
         [0002]    There are numerous different configurations and constellations of gearwheel pairs in which two gearwheels interact with one another. The gearwheel pairs may be dimensioned and designed appropriately depending on the intended purpose and field of use. A gearwheel pair forms a simple gear or may be used as a component of a gear train.  
           [0003]    Two gear constructions are differentiated between according to the mutual position of the wheel axes and/or the shafts of a gearwheel pair and according to the direction of the flanks: specifically rolling gear transmission and helical rolling type gear transmission.  
           [0004]    Spur gears and bevel gear pairs are examples of rolling gear transmissions. Spur helical gears, bevel helical gears, and worm gear pairs, in contrast, are referred to as helical rolling type gear transmissions.  
           [0005]    All of the known gear types are distinguished by certain specific advantages, which are, however, connected to certain disadvantages without exception.  
           [0006]    The rolling gear transmissions, for example, are simple to manufacture and have low wear and good efficiency because they only roll on one another.  
           [0007]    The helical rolling type gear transmissions are distinguished by quiet running, for example.  
           [0008]    Large transmission ratios may not be implemented at a reasonable outlay and with compact dimensions using any of the known gear types. The exception is worm gears, which have poor efficiency, however. Planetary gear transmissions are to be considered a special case in this context, since these require more than one gearwheel pair per transmission ratio step.  
           [0009]    It is an object of the present invention to avoid the disadvantages of the known gear types.  
           [0010]    It is an object of the present invention to, as much as possible, combine all advantages of the known gears in a novel gear geometry and to provide a corresponding gearwheel and/or gear.  
           [0011]    These objects are achieved by the characterizing features of claim  1  and by the characterizing features of claim  10 , each in connection with the features of the preamble.  
           [0012]    Different advantageous embodiments may be inferred from dependent claims  2 - 9  and  11 - 18 . 
       
    
    
       [0013]    Further details and advantages of the present invention are described in the following on the basis of preferred exemplary embodiments with reference to the drawing, which is implemented as simplified schematic illustrations.  
         [0014]    [0014]FIG. 1 shows a first gearwheel pair (torus spiral gear) in a perspective illustration with a driving torus wheel and a driven spur wheel, according to the present invention;  
         [0015]    [0015]FIG. 2 shows a schematic illustration of the first gearwheel pair shown in FIG. 1, having the two functional faces (pitch surfaces), which represent a toric section and a cylinder;  
         [0016]    [0016]FIG. 3 a  shows a detail of a spiral-toothed spur wheel, according to the present invention, having its non-parallel left (e.g., concave, convex, or straight) and right convex tooth flanks;  
         [0017]    [0017]FIG. 3 b  shows a detail of a top view of the spiral-toothed spur wheel shown in FIG. 3 a;    
         [0018]    [0018]FIG. 4 shows the tooth meshing between a torus wheel and a spiral-toothed spur wheel according to a further gearwheel pair according to the present invention;  
         [0019]    [0019]FIG. 5 shows the torus wheel having a spiral-toothed spur wheel in front of it, as shown in FIG. 4;  
         [0020]    [0020]FIG. 6 shows a schematic illustration of the three tooth curves of a torus wheel provided with three teeth according to a further embodiment according to the present invention;  
         [0021]    [0021]FIG. 7 shows a schematic illustration of a torus wheel having a tooth curve which deviates from the ideal spiral at multiple points, according to a further embodiment according to the present invention;  
         [0022]    [0022]FIG. 8 shows the tooth meshing between a torus wheel having an expanded gap width and a spiral-toothed spur wheel having an expanded tooth thickness, according to a further embodiment according to the present invention;  
         [0023]    [0023]FIG. 9 shows the teeth of a further torus wheel having a possibility for the design of the tooth flank profile, according to a further embodiment according to the present invention;  
         [0024]    [0024]FIG. 10 shows the teeth of the spur wheel having a possibility for the design of the tooth flank profile, according to a further embodiment according to the present invention;  
         [0025]    [0025]FIG. 11 shows the teeth and pitch surface of a further gearwheel having a convex pitch surface shaped like a toroidal segment, according to the present invention;  
         [0026]    [0026]FIG. 12 shows the teeth and pitch surface of a further gearwheel having a concave pitch surface shaped like a toroidal segment, according to the present invention;  
         [0027]    [0027]FIG. 13 shows the teeth and pitch surface of a further gearwheel having a convex pitch surface shaped like a toroidal segment, according to the present invention;  
         [0028]    [0028]FIG. 14 shows the teeth and pitch surface of a further gearwheel having a concave pitch surface shaped like a toroidal segment, according to the present invention;  
         [0029]    [0029]FIG. 15 shows the teeth and pitch surface of a further gearwheel having a convex pitch surface shaped like a spherical segment, according to the present invention;  
         [0030]    [0030]FIG. 16 shows the teeth and pitch surface of a further gearwheel having a concave pitch surface shaped like a spherical segment, according to the present invention;  
         [0031]    [0031]FIG. 17 a  shows a top view of a pair of gears according to the present invention;  
         [0032]    [0032]FIG. 17 b  shows a side view of the pair of gears shown in FIG. 17 a ; and  
         [0033]    [0033]FIG. 18 shows a further pair of gears according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0034]    In the following, different exemplary embodiments are provided. The expressions typical in gearing technology, which may be inferred from the DIN 3998 handbook or the DIN 868 handbook, for example, are used as the basis for the concept definitions.  
         [0035]    A first gearwheel pair  1  (gear) according to the present invention as shown in FIG. 1 includes a first gearwheel  4  and a second gearwheel  8 . The first gearwheel  4  is used as the drive wheel  4  and the second gearwheel  8  as the driven wheel. The two wheel axes  2  and  3  are approximately perpendicular to one another in the example shown, i.e., the axis angle is 90°±10°. The driving wheel  4  is a torus wheel having teeth  7  which run in a spiral shape. The driven wheel  8  is a spur wheel having curved external teeth  10 .  
         [0036]    Through this arrangement of the axes  2  and  3  and the teeth, two geometrically different pitch surfaces (shown hatched) result, as shown in FIG. 2, specifically an annular face (toric section)  5  and a cylinder surface  9 . From the statements above, the gear  1  may thus be referred to as a helical rolling type gear transmission. The torus wheel  4  is provided with one or more teeth  7 , each of the teeth  7  having a tooth curve running in a spiral. The coordinate origin  30  of all tooth curves running in a spiral is preferably a shared point lying on the wheel axis  2  in this case.  
         [0037]    The spur wheel  8  has at least three teeth  10  applied in a curve. An exemplary detail in regard to the spiral teeth of the spur wheel  8  having concave left flanks  11   a,    11   b  and convex right flanks  12   a,    12   b  is shown in FIGS. 3 a  and  3   b  as a detail of the spur wheel  8 . It is to be noted that the left flanks could also be straight or convex instead of concave. The tooth curve  23   a  and  23   b  is defined in connection with the present description as the intersection line (passage line) of the tooth central planes  121   a  and/or  121   b  with the upper tooth faces  122   a,    122   b.  The tooth central planes  121   a  and  121   b  run in a fan shape in relation to one another and have a shared axis of intersection, which is coincident with the axis of rotation of the spur wheel  8 . This axis of intersection is not visible in FIG. 3. The spur wheels  8  according to the present invention are distinguished in that each active flank region has at least one line which runs parallel to the same line of the neighboring tooth. The concave left flank  11   a  has, for example, the line  123   a  in the example shown, which runs parallel to the same line  123   b  of the concave left flank  11   b  of the neighboring tooth. The convex right flank  12   a  has the line  124   a  in the example shown, which runs parallel to the same line  124   b  of the convex right flank  11   b  of the neighboring tooth.  
         [0038]    According to the present invention, the inner flanks (indicated in FIGS. 3 a  and  3   b  as left flanks  11   a,    11   b ) may be shaped convex, straight, or concave. The outer flanks (indicated in FIGS. 3 a  and  3   b  as right flanks  12 ,  12 ) are implemented as convex (or as a polygonal approximation of a convex shape), the radius of curvature of these flanks being greater than the radius of the tooth curve of the teeth applied in a spiral shape on the pitch surface of the torus wheel  5 .  
         [0039]    The tooth curve  23   a  and the curve of the lines  123   a  and  124   a  are not necessarily parallel.  
         [0040]    The second gearwheel  8  preferably has a cylindrical pitch surface  9 , which is positioned concentrically to the wheel axis  3  of the second wheel  8 .  
         [0041]    A further embodiment of a gearwheel pair  46  according to the present invention is shown in FIG. 4. The torus wheel  24  has an at least partially curved pitch surface  26  which carries teeth having at least one tooth  27 . The tooth/teeth  27  has/have a spiral tooth curve. In FIG. 4, the tooth meshing of the torus wheel  24  and the spur wheel  28  is shown. The curved pitch surface  26  is implemented as a concave toric section.  
         [0042]    The curve of the teeth  27  of the torus wheel  24  applied in a spiral shape and the teeth  25  of the spur wheel  28  and the interplay of the teeth  27  and the spiral-toothed teeth  25  is shown again in FIG. 5 with the torus wheel  24  and the spur wheel  28  visible.  
         [0043]    In order, as shown in FIG. 6, to obtain not only transmission ratios corresponding to the tooth number of a (driven) cylinder wheel, the (driving) torus wheel may have multiple teeth according to a further embodiment. Such a torus wheel is referred to as a multi-thread torus wheel. The tooth curves  6   a,    6   b,    6   c  of the teeth of such a torus wheel are positioned on the pitch surface as spirals whose shared coordinate origin  30  lies on the wheel axis of the torus wheel. The spirals are preferably Archimedean spirals, as indicated in FIG. 6, which are distinguished by constant coil intervals over the entire definition region A.  
         [0044]    In the embodiment shown in FIG. 6, the spirals, viewed outward in the radial direction from the shared coordinate origin  30 , have a uniform tooth spacing of the intervals of the tooth curves  6   a,    6   b,    6   c.  The origin vectors  29   a,    29   b,    29   c  of the tooth curves  6   a,    6   b,    6   c  running in a spiral are preferably distributed uniformly on 360°, so that the uniform tooth spacing is maintained.  
         [0045]    [0045]FIG. 7 relates to a special embodiment of a gear according to the present invention. In the embodiment of the present invention described up to this point (see FIG. 5 or  6 , for example) the tooth curves  6   a,    6   b,    6   c  of the spiral teeth  7  and/or  27  of the driving wheel  4  and/or  24  run around the coordinate origin  30  with uniform pitch. Uniform speed of the driven spur wheel  8  is thus ensured. However, if non-uniform angular speeds on the spur wheel  8  and/or  25  are desired, these may be produced through deviations from the uniform curve of the spirals. For example, flattenings may be provided in the curvature of the spirals. In connection with the present invention, a deviation of the curvature of a spiral from the uniform curve is referred to as a flattening. In FIG. 7, the example of a tooth curve  31  having flattenings  14  is shown. The uniform curve of the tooth curve  31  is shown in dashed form. In an angle section a, the tooth curve  31  deviates from the uniform curve, as is indicated by the thick line  32 .  
         [0046]    [0046]FIG. 8 shows a further embodiment of a gearwheel pair  49  according to the present invention. The first gearwheel  34  has an at least partially curved pitch surface  33  (indicated by a dashed line in FIG. 8). Teeth having multiple teeth  37  are located on the pitch surface  33 . The tooth curves of the teeth  37  have a spiral curve. The second wheel  38  is a cylinder wheel having a cylindrical pitch surface  39  (indicated in FIG. 8 by a dashed, circular line), which has external teeth having teeth  35 . The external teeth are spiral teeth having concave left flanks  41  and convex right flank  42 , the concave left flanks  41  not running parallel to the convex right flanks  42 . The possibility of a specific pitch  15 ,  16  of the gearwheel  34  and/or the cylinder wheel  38  is shown in FIG. 8. The pitch  15 ,  16  is a non-uniform pitch in tooth gaps  17 ,  18  and tooth widths  19 ,  20 . The pitch is preferably performed in such a way that the gearwheel  34  has gaps  17  between neighboring teeth  37 , whose width  17  is selected differently than the width  18  of the gaps between neighboring teeth  35  of the cylinder wheel  38 . In another case, the thickness  19  of the teeth  37  (also referred to as tooth width) of the gearwheel  34  is selected in such a way that it differs from the thickness  20  of the teeth  35  of the cylinder wheel  38 . A combination of these two provisions is also possible. Through such a pitch, the specific conditions in regard to strength values for the driving and/or driven wheel may be taken into consideration appropriately.  
         [0047]    Two possible tooth shapes according to the present invention may be seen in FIGS. 9 and 10. FIG. 9 shows multiple teeth  47  of a further torus wheel  44 . The curved pitch surface  43  is indicated in FIG. 9 by a dashed line. The pitch surface  43  is implemented as concave in the embodiment shown. There are numerous possibilities for designing the tooth flank profile of the teeth  47 . FIG. 10 shows several teeth  40  of a spur wheel  48 . The pitch surface  45  of the spur wheel  48  is cylindrical. There are also numerous possibilities for designing the tooth flank profile for the teeth  40 . The selection of the tooth shape in regard to the flank profiles  21  and  22  is influenced by the manufacturing method, the manufacturing tool used, and the desired properties of the gear.  
         [0048]    The teeth  57  and the pitch surface  53  of a further gearwheel  54  according to the present invention are shown in FIG. 11. The pitch surface  53  is convex and has the shape of a toric segment. The gearwheel  54  has a raised surface  51 , preferably implemented as even, in the example shown.  
         [0049]    The teeth  67  and the pitch surface  63  of a further gearwheel  64  according to the present invention are shown in FIG. 12. The pitch surface  63  is concave and has the form of a toric segment. The gearwheel  64  has a recessed surface  61 , which is preferably implemented as even. The surface  61  is in a recess  62  in the example shown.  
         [0050]    The teeth  77  and the pitch surface  73  of a further gearwheel  74  according to the present invention are shown in FIG. 13. The pitch surface  73  is convex and has the form of a toric section. The gearwheel  74  has a recessed surface  71 , preferably implemented as even. The surface  71  is in a recess  72  in the example shown.  
         [0051]    The teeth  87  and the pitch surface  83  of a further gearwheel  84  according to the present invention are shown in FIG. 14. The pitch surface  83  is concave and has the form of a toric section. The gearwheel  84  has a recessed surface  81 , preferably implemented as even. The surface  81  is in a recess  82  in the example shown.  
         [0052]    The teeth  97  and the pitch surface  93  of a further gearwheel  94  according to the present invention are shown in FIG. 15. The pitch surface  93  is convex and has the form of a spherical segment. The gearwheel  94  has a slightly recessed surface  91 , preferably implemented as even.  
         [0053]    The teeth  107  and the pitch surface  103  of a further gearwheel  104  according to the present invention are shown in FIG. 16. The pitch surface  103  is concave and has the form of a spherical segment. The gearwheel  104  has a recessed surface  101 , preferably implemented as even, in the example shown. The surface  101  is in a recess  102 .  
         [0054]    The embodiments shown in FIGS. 12, 14, and  16  are distinguished in that more than two teeth of the spur wheel are always engaged.  
         [0055]    The installation position of the two wheels of the pair of gears  4  and  8  is shown in FIGS. 17 a  and  17   b  on the basis of an x, y, z coordinate system. The rotational axis  3  of the spur wheel  8  may deviate from the perpendicular position at y=0° in the x-y plane. Preferably, for the angle y: −45°&lt;y&lt;45°. In addition, the rotational axis  3  may be tilted slightly in relation to the horizontals, as indicated in FIG. 17 b.  The tilt is defined by the angle β, for which: −10°&lt;β&lt;10°.  
         [0056]    In a further embodiment, which is indicated in FIG. 18, the spur wheel  108  is positioned offset in relation to the torus wheel  114 .  
         [0057]    According to the present invention, one of the gearwheels (also referred to as the torus wheel) has a curved pitch surface, at least a section of which is implemented as concave or convex. The pitch surface according to the present invention is thus designed as toroidal or spherical in at least one section, the section of the pitch surface being  
         [0058]    a toric section,  
         [0059]    a spherical section,  
         [0060]    a toric segment, or  
         [0061]    a spherical segment.  
         [0062]    The section of the pitch surface is positioned concentrically to the wheel axis of the gearwheel.  
         [0063]    The field of use of gears described above extends over all of drive technology. The present invention is especially suitable for use in elevator construction, vehicle construction, and mechanical engineering in general. The present invention is especially suitable for use in cableways, crane hoists, etc.  
         [0064]    As an expanded variant, the gear may be constructed as multiple pairs of gears (gear train). A gear train which combines both spiral-toothed pairs of gears and known pairs of gears such as spur wheels, bevel wheels, or others is also conceivable.  
         [0065]    The use of the gear upon which this patent specification is based is connected with many advantages in dividers, turntables, or circular swivel units. One of these advantages is the slight tooth backlash, which may be set through axial displacement of the driving planar wheel.  
         [0066]    It is an advantage of the gearwheel pair according to the present invention that it may be implemented as self-locking. In such a self-locking embodiment, the spur wheel may not drive the torus wheel.  
         [0067]    It is also advantageous that, depending on the embodiment, multiple teeth are always engaged. In addition, a gearwheel pair according to the present invention may be constructed compactly. Transmission ratios of up to 200 per gearwheel pair step may be implemented. A gearwheel pair according to the present invention is distinguished by very high efficiency, since there is a fluid friction between the transmitting tooth flanks.  
         [0068]    The installation of the gear upon which this patent specification is based is also very advantageous in conveyor technology, especially in chain hoists, cable hoists, and lifts. The self-locking cited may replace or supplement safety elements such as brakes.