Abstract:
In a toothed piece for a geared motor, series of geared motors and connection, the toothed piece, for a connection with a motor shaft of the electric motor, having at least a first toothing in a first axial region, and having at least a second toothing in a second axial region, the second toothing meshing with a running toothing of a further toothed piece of the gear unit.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a toothed piece for a geared motor, a series of geared motors and a connection. 
     BACKGROUND INFORMATION 
     U.S. Pat. No. 3,242,998 describes a toothed piece, driven by a toothed motor shaft, for a connection to an output shaft, which has a first toothing in a first region and a second toothing in a second region. In this case, an internal toothing must be produced in a complicated and expensive manner. 
     A shank pinion is also described as a toothed piece in European Published Patent Application No. 0 989 316. However, during mounting, centering may only be provided in a costly manner. 
     In German Patent Published Patent Application No. 26 07 363, the toothed piece has two helical toothings. However, centering during mounting is again costly. 
     German Published Patent Application No. 296 03 748 describes a pin for an adapter, the pin being usable for centering upon insertion. 
     Geared motors are conventional whose motor shaft drives an externally-toothed pinion, whose toothing meshes with an externally-toothed gear wheel having a running toothing or running gear. 
     To reduce noise, involute toothings having a non-vanishing helix angle are used for these toothings. A disadvantage in this case is that, during the transmission of torque, axial forces develop which must be absorbed by further components such as bearings. 
     Therefore, it is an object of the present invention to provide a pinion for a geared motor in such a manner that less expensive parts may be used in the gear unit or, in a more cost-effective manner, parts may even be omitted in the gear unit. 
     SUMMARY 
     According to an example embodiment of the present invention, the foregoing and other beneficial objects may be achieved by providing a toothed piece for a geared motor according to the features described herein, and by providing a connection according to the features described herein. 
     Features of the present invention with respect to the toothed piece include that, for a connection to a motor shaft of the electric motor, the toothed piece has at least a first toothing in a first axial region, and at least a second toothing in a second axial region, the second toothing meshing with a running toothing of a further toothed piece of the gear unit. In this context, it may be provided that the second toothing may be implemented with a different pitch circle diameter than the first toothing. Therefore, on the motor side, different toothed pieces are useable within one size for different variants. The toothed pieces are able to be implemented with always the same first toothing on the motor side, and with different second toothings on the gear unit side. In this manner, a motor shaft of the same kind may be used within the size for each variant, it being possible to realize different transmission ratios at the first input stage of the gear unit. Another aspect is that a high torque may be able to be transmitted from the motor shaft to the toothed piece with the aid of the first toothing. 
     In an example embodiment of the present invention, the motor shaft has a driver toothing which meshes with the first toothing of the toothed piece. Not only is a high torque transmittable, but the toothings may also be produced inexpensively using industrially common toothing machines. 
     In an example embodiment of the present invention, the first and second toothings are each helical toothed and have the same algebraic sign for the helix angle and/or have the same helix angle. This may provide that the components of axial force, generated by the helical toothings, onto the toothed piece itself may be influenced in the design by the selection of the helix angles and the toothing data so that a reduced, resulting component of axial force onto the toothed piece itself is attainable. Improvements in the design of the gear unit may be achieved by this reduction in the resulting axial force onto the toothed piece itself. Other parts may be implemented more cost-effectively or even dispensed with, such as suitable retaining rings, etc. 
     In an example embodiment of the present invention, the first and second toothings are involute toothings. Such industrially common toothings may be produced inexpensively, easily and quickly on suitable production machinery. 
     In an example embodiment of the present invention, the first and/or second toothing is/are external toothings. The toothed piece has may have a compact form and therefore may be produced inexpensively. External toothings may be manufactured simply, quickly and inexpensively using large milling cutters, and after the hardening, using large grinding wheels. 
     In an example embodiment of the present invention, the pitch circle diameter of the first toothing is larger than the pitch circle diameter of the second toothing. A smaller gear wheel may also be used in the first gear stage, including second toothing of the shank pinion and gear wheel, which means it may also be possible to realize small transmission ratios. 
     In an example embodiment of the present invention, the toothed piece has, at its motor-side end, a pin or plug which is inserted in such a manner into a corresponding cut-out in the motor shaft that, upon insertion into the cut-out, it may be used for centering the toothed piece. This may provide easy and quick production. In particular, the centering may also permit a highly precise, and at the same time, quickly executable assembly. 
     In an example embodiment of the present invention, the pin may be cylindrical. The pin may be produced inexpensively. 
     In an example embodiment of the present invention, the pin may be conical. This may provide that assembly may be accomplished particularly quickly, and even if the toothed piece deviates from the ideal position prior to or during assembly, a centering may take place automatically correctly upon insertion into the motor shaft. 
     In an example embodiment of the present invention, the pin may have a knurling. The knurling may have a greater hardness than the material of the motor shaft, and therefore may be able to be pressed into the motor shaft, accompanied by material deformation. Therefore, in the case of small torques, the connection of the toothed piece to the motor shaft is implemented via this press connection. Only after a critical torque is exceeded is the driver toothing of the motor shaft usable with the first toothing of the toothed piece for the torque transmission. 
     In an example embodiment of the present invention, the toothed piece may have a cut-out which, upon introduction into the motor shaft, is useable for centering the toothed piece. The toothed piece may have only a short length, and therefore may need less storage space and assembly space. In particular, it may be rotatable on a smaller space volume during the assembly. It also may have less volume of material. Because of the higher torque to be transmitted and the greater hardness for the machine grinding of the toothings, the material of the toothed piece may be more expensive than the material for the motor shaft, for which structural steel may also be used. 
     In an example embodiment of the present invention, the first and second toothings may be included by a single toothing. This may provide that production may be particularly simple, and a high transmission ratio may be realized. 
     In an example embodiment of the present invention, the driver toothing of the motor shaft may be an inner toothing. This may provide that it may be produced inexpensively using industrially common production methods, e.g., by striking, broaching, original forming and/or milling, etc. 
     Features of the present invention with respect to the series of geared motors are that the series includes at least one size, and each size includes one or more variants of geared motors. Within one size, substantially identical motor shafts, which in each case are connectible and/or connected to a toothed piece, are usable for different variants. Within one size, at least one variant includes a toothed piece whose first and second toothings are different. At least one further variant includes a toothed piece whose first and second toothings are identical. In this context, it may be provided that, by the use of different toothed pieces, it may be possible to realize a wide range of different transmission ratios. In particular, not only the toothing data may be varied, accompanied by an essentially constant pitch circle diameter, but also the pitch circle diameters may be varied within one size for the variants. This may enlarge the range of transmission ratios considerably. 
     In addition, it is possible to use an involute toothing as a first toothing, and as a second toothing, to use a pinion for a helical-bevel gear stage, or a pinion for another type of gear stage such as, for example, a planetary gear stage, a gear stage having a spiroidally toothed wheel or other bevel gear stages. Therefore, even a motor shaft which is always substantially identical may be used for various types of the input gear stage. 
     Features of the present invention with respect to the connection from a first rotating part via a toothed piece to a part having a running toothing are that the toothed piece has a second toothing which meshes with the running toothing. The toothed piece has a first toothing which meshes with a driver toothing of the first rotating part. The helix angles of the first and the second toothing are selected so that the direction of the axial force, generated by the driver toothing and first toothing, onto the toothed piece itself, and the direction of the axial force, generated by the running toothing and second toothing, onto the toothed piece itself are opposite, in order to decrease the resulting axial force onto the toothed piece itself. This may provide that the components of axial force, generated by the helical toothings, onto the toothed piece itself may be influenced in the design by the selection of the helix angles and the toothing data so that a reduced, resulting component of axial force onto the toothed piece itself is attainable. Improvements in the arrangement of the total device may be achieved by this reduction in the resulting axial force onto the toothed piece itself. Other parts may be implemented more cost-effectively or even dispensed with, such as suitable retaining rings, etc. 
     Further example embodiments and developments are set forth below. 
     The present invention shall now be explained in detail with reference to the accompanying Figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of an example embodiment of a toothed piece according to the present invention. 
         FIG. 2  is a schematic view of an example embodiment of a toothed piece according to the present invention. 
         FIG. 3  is a schematic partial cross-sectional view of a motor adapted to mesh with the toothing of the toothed piece. 
         FIG. 4  is a partial cross-sectional view illustrating an example embodiment of the present invention. 
         FIG. 5  is a schematic view of an example embodiment of a toothed piece according to the present invention. 
         FIG. 6  is a schematic view of an example embodiment of a toothed piece according to the present invention. 
         FIG. 7  is a schematic view of an example embodiment of a toothed piece according to the present invention. 
         FIG. 8  is a schematic view of an example embodiment of a toothed piece according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a shank pinion  3  which has a first toothing  1  and a second toothing  2 , first toothing  1  having a smaller pitch circle diameter than second toothing  2 . First toothing  1  and second toothing  2  each have a negative helix angle of the same amount. In other exemplary embodiments of the present invention, different amounts may also be used. 
       FIG. 2  shows a shank pinion  23  which has a first toothing  21  and a second toothing  22 , first toothing  21  again having a smaller pitch circle diameter than second toothing  22 . First toothing  21  and second toothing  22  each have a positive helix angle of the same amount. 
     The helix angle is denoted symbolically in  FIGS. 1 and 2  by three parallel marks. In the figures, M designates the motor-side axial end of the shank pinion, and G designates the axial end of the shank pinion on the gear unit side. 
     In  FIG. 3 , a motor  31  is partially indicated, whose motor shaft  32  has a bore hole having a driver toothing  34 , implemented as an inner toothing, with which first toothing  1 ,  21  of shank pinion  3 ,  23  meshes. 
     In addition, the motor shaft has a cut-out  33  for centering a shank pinion provided with a corresponding pin. In other exemplary embodiments of the present invention, motor shaft  32  may be implemented without a cut-out, shank pinions  3 ,  23  according to  FIG. 1  or  2  then being used. 
       FIG. 4  shows a shank pinion  42  which has a cylindrical pin  43  for centering upon insertion into motor shaft  41 . With second toothing  2  as running toothing, shank pinion  42  meshes with gear wheel  44  of the gear unit. 
     Driver toothing  45 , arranged as a helical toothing and meshing with first toothing  46  arranged as a helical toothing, generates a component of axial force onto the toothed piece. The running toothing of gear wheel  44 , together with the second toothing of shank pinion  42 , generates an oppositely directed component of axial force onto the toothed piece itself. Therefore, the resulting component of axial force onto the toothed piece itself has only a small or even vanishing value, depending upon the selection of the helix angles and the toothing data. 
       FIG. 5  shows a shank pinion  51  having a conical pin  52  for the centering in a correspondingly conical cut-out and/or bore hole in the motor shaft. 
       FIG. 6  shows a shank pinion  61  which has a first toothing  63  and a second toothing  64 . In addition, shank pinion  61  has a cut-out  62  for the centering, the motor shaft having a corresponding form or, in other exemplary embodiments of the present invention, the motor shaft being provided with corresponding parts. 
       FIG. 7  shows a shank pinion  71  having a pin provided with a knurling  72 . Since shank pinion  71  is made of a hardened material and/or a material having a greater hardness, shank pinion  71  is able to be pressed into the softer motor shaft, made of structural steel, accompanied by material deformation. 
     Instead of structural steel, other materials may also be used which are less hard than the shank pinion. 
       FIG. 8  shows an example embodiment of the present invention, shank pinion  81  having a helical-toothed toothing  82  which, on the motor side, meshes with the correspondingly helical-toothed driver toothing of the cut-out of the motor shaft, and on the gear unit side, meshes with the running toothing of a correspondingly helical-toothed gear wheel of the gear unit. Therefore, it may only be necessary to produce a single toothing, which may be particularly simple and cost-effective. 
     Thus, shank pinions according to  FIG. 8 , for which toothing data such as, e.g., root diameter, outside diameter and pitch circle diameter of the first and of the second toothing are identical, may be used in a series of gear units having several gear ratios within one size. In addition, shank pinions according to  FIG. 1  are usable with the same motor shaft. Since, therefore, different shank pinions having, in each case, a different second toothing but identical first toothing may be used, it is possible to realize a wide range of transmission ratios. 
     In further example embodiments of the present invention, the foregoing may also be used for other types of toothing. For example, the first toothing of the shank pinion is a helical-toothed involute toothing, and the second toothing meshes with a bevel gear or a spiroidally toothed wheel. Thus, cylindrical or non-cylindrical second toothings are also possible. 
     In other example embodiments of the present invention, the foregoing may be used not only for gear units, but also for other devices which include a connection from a first rotating part, such as a shaft, via a toothed piece to a part having a running toothing. In this context, in the manner shown in the Figures, the toothed piece may be arranged with a first and second toothing, each having the same algebraic sign of the helix angle, such that the axial force components generated in each instance act in the opposite direction. Therefore, the aspects and effects indicated above may also be achieved for other devices.