Patent Publication Number: US-2021162857-A1

Title: Wheel drive module with a wheel received in the wheel drive module

Description:
The invention relates to a wheel drive module comprising a wheel received at least sectionally in the wheel drive module. 
     In the prior art, a plurality of wheel drive modules and wheel drive designs for the different application fields are already known. If the wheel drive designs are to be bundled to form a single module, it is advantageous if said module is of compact design and consequently has only a low space requirement. In particular in the case of the use of such a wheel drive module for logistic applications, for example, in the case of transport carriages, a low installation space requirement and improved steerability are advantageous. In the designs disclosed in the prior art, a wheel is usually rotated about a steering axis and thereby steered. A transmission for transmitting a rotation of a motor to the wheel is usually arranged offset and spaced apart from the wheel, which leads to a high installation space requirement. In addition, in the designs known from the prior art, the wheel has a limited steering angle and during a steering movement, for example, it cannot be rotated or turned by more than 360°. As a result, the space requirement in the prior art is usually too high and the possible steering angles or rotation angles about the steering axis are limited. 
     The underlying aim of the invention therefore is to overcome the aforementioned disadvantages and to provide a wheel drive module which has an increased steering angle of the wheel as well as a low installation space requirement and which can be produced as a compact and cost-effective modular unit. 
     This aim is achieved by the combination of features according to claim  1 . 
     According to the invention, a wheel drive module with a wheel and a transmission is proposed. The transmission of the wheel drive module comprises a first and a second drive gear ring. The drive gear rings can be rotated about a common rotation axis and are arranged spaced apart from one another along the rotation axis, wherein they can rotate independently of one another about their rotation axis and for this purpose are driven, for example, by a respective drive motor. The wheel can be steered and driven by a respective rotation of the first drive gear ring and of the second drive gear ring. Furthermore, to save installation space and to widen the steering angle between the first drive gear ring and the second drive gear ring, a wheel-receiving space is defined, which extends along the rotation axis and is, in particular, cylindrical, in which the wheel is at least sectionally arranged. In addition, the wheel is preferably arranged with its width extent orthogonal to the rotation axis centered on the rotation axis. 
     The first and the second drive gear rings are preferably each formed as a crown gear which comprises a first toothing facing the driven gearwheel and engaging in the driven gearwheel, and a second driving toothing via which the respective crown gear can be driven. 
     An advantageous embodiment provides that the wheel drive module additionally comprises an output shaft with a driven gearwheel fastened thereon. For transmitting the rotations of the first and second drive gear rings to the wheel, the output shaft is connected in a rotationally fixed manner to the wheel and comprises the driven gearwheel on a side spaced apart from the wheel in longitudinal direction of the output shaft, said driven gearwheel being also fastened in a rotationally fixed manner on the output shaft. The modular unit consisting of the output shaft with the wheel and the driven gearwheel is mounted so that it can rotate about a wheel axis extending orthogonally to the rotation axis and can be driven by the first and the second driving gear rings. The rotation of the modular unit consisting of output shaft with the wheel and the driven gearwheel about the rotation axis of the drive gear rings leads to a rotation of the wheel about the rotation axis and thus to a steering movement of the wheel about the rotation axis, wherein the rotation axis of the drive gear rings is used as steering axis. 
     A first rotation transmitted by the first drive gear ring to the driven gearwheel and/or a second rotation transmitted by the second drive gear ring to the driven gearwheel moves the driven gearwheel in a third rotation about the wheel axis, wherein the wheel is set in rotation via the output shaft about the wheel axis and thereby driven. Furthermore, as a result of a first rotation of the first drive gear ring and a second rotation of the second drive gear ring about the rotation axis of the first and second drive gear rings, a rotation of the modular unit consisting of the driven gearwheel, the output shaft and the wheel about the rotation axis and thus the steering movement can also occur, so that the wheel can be steered by the rotation of the first and second drive gear rings. 
     If the first drive gear ring and the second drive gear ring rotate about their common rotation axis with the same rotational speed in opposite directions, the driven gearwheel is rotated about the wheel axis without rotation or turning of the driven gearwheel, of the output shaft or of the wheel about the rotation axis of the drive gear rings occurring. As a result of the mutually opposite and equal-amount rotations of the drive gear rings, a driving of the wheel without steering movement is implemented. 
     If the first drive gear ring and the second drive gear ring rotate about their rotation axis with the same rotational speed in an identical direction, the driven gearwheel is not rotated about the wheel axis and is rotated exclusively about the rotation axis of the driving gear rings, so that a steering movement of the wheel without driving of the wheel about the wheel axis occurs. 
     If the first drive gear ring and the second drive gear ring rotate about their rotation axis with different rotational speed in opposite or identical directions about their rotation axis, or if a drive gear ring does not move, a steering movement about the rotation axis of the drive gear rings and a driving about the wheel axis simultaneously occur on the wheel. 
     An alternative and also advantageous development of the wheel drive module provides that the drive gear rings do not drive the output shaft directly via the driven gearwheel but instead drive it indirectly via an intermediate shaft which is offset with respect to the output shaft along the rotation axis of the drive gear rings. For this purpose, the wheel drive module additionally comprises an intermediate shaft, a driving intermediate wheel and a driven intermediate wheel. The intermediate shaft extends along an intermediate axis, about which the intermediate shaft with the driving and driven intermediate wheels is rotatably mounted. The driving intermediate wheel and the driven intermediate wheel are arranged along the intermediate axis on mutually opposite sides of the intermediate shaft and are connected at least in a rotationally fixed manner to it. Furthermore, the driving and the driven intermediate wheels are each designed as a gearwheel, wherein the driving intermediate wheel engages in the first and second driving gear rings and the driven intermediate wheel engages in the driven gearwheel. The first and second rotations of the drive gear rings can be transmitted as a rotation of the intermediate shaft via the intermediate shaft to the output shaft, and the wheel can be driven about the wheel axis. The rotation of the intermediate shaft here generates the third rotation of the output shaft. By the gearwheel pairing consisting of driven gearwheel and driven intermediate wheel, a transmission between intermediate shaft and output shaft can be additionally implemented. The intermediate shaft and the output shaft are fixed in terms of their relative position with respect to the rotation axis of the drive gear rings, as a result of which a rotation of the intermediate shaft about the rotation axis leads to a rotation of the output shaft about the rotation axis, and a steering movement of the wheel about the rotation axis is carried out. The intermediate axis and the wheel axis are preferably parallel to one another. Furthermore, due to the offset with respect to the intermediate axis, the wheel axis preferably extends outside of the intermediate space between the drive gear rings. 
     In an advantageous variant of the wheel drive module, the first drive gear ring and/or the second drive gear ring comprise/comprises an axially central ring opening which in each case extends along the common rotation axis of the first drive gear ring and of the second drive gear ring through the respective or the first drive gear ring and/or the second drive gear ring. The ring opening widens or the ring openings widen the wheel-receiving space along the rotation axis. 
     If the wheel drive module or at least one of the drive gear rings comprises such a ring opening, an advantageous embodiment variant provides that the wheel extends through the ring opening of the first drive gear ring and/or the ring opening of the second drive gear ring and extends along the rotation axis beyond the first drive gear ring and/or the second drive gear ring. 
     The ring opening of the first drive gear ring and/or the ring opening of the second drive gear ring are/is preferably designed concentrically to the rotation axis. 
     Furthermore, an advantageous development provides that the wheel drive module comprises a cover plate which is arranged on the first drive gear ring or the second drive gear ring, and covers or closes the respective ring opening. If the wheel extends through the ring opening of the two drive gear rings, it is in contact on one side with the ground or with a running surface. On the opposite side of the wheel, said wheel protrudes beyond the drive gear ring of this side. On the side on which the wheel is not in contact with the ground, the wheel can be covered by the cover plate, so that, for example, dirt cannot penetrate into the wheel-receiving space. Alternatively, the cover plate is not connected to one of the drive gear rings but instead is mounted on the output shaft, so that, for example, forces acting on to the wheel through the ground can be supported via the output shaft and the cover plate. 
     In order to minimize or prevent the penetration of dirt into the wheel-receiving space through a ring opening on the side of the ground, an advantageous embodiment furthermore provides that the wheel drive module comprises a protective plate which is arranged on the first drive gear ring or the second drive gear ring facing the ground. The protective plate is arranged so that it can rotate together with the wheel about the rotation axis and is received so that it can rotate independently of the first and second drive gear rings. In addition, the protective plate comprises a preferably slot-shaped protective plate opening through which the wheel extends. 
    
    
     
       Other advantageous developments of the invention are characterized in the dependent claims or represented in further detail below together with the description of the preferred embodiment of the invention in reference to the figures. The figures show: 
         FIG. 1  a perspective representation of a wheel drive module with the drive motors driving the drive gear rings; 
         FIG. 2  a perspective representation of a wheel drive module with intermediate shaft; 
         FIG. 3  a cross-sectional representation of a first wheel drive module; 
         FIG. 4  a cross-sectional representation of a second wheel drive module. 
     
    
    
     The figures are diagrammatic examples. Identical reference numerals in the figures refer to functionally and/or structurally identical features. 
     In  FIG. 1 , the wheel drive module  1  together with the drive motors  11 ,  21  which drive the first and the second drive gear rings  15 ,  25  is represented. The first drive motor  11  is arranged opposite the second drive motor  21 , wherein the drive motors  11 ,  21  can each comprise a separate motor transmission. Via a respective motor shaft  12 ,  22 , the drive motors  11 ,  21  are each connected to a pinion  13 ,  23 . 
     The first pinion  13  engages its toothing in a toothing of a first intermediate wheel  14  which engages by means of its toothing in a drive toothing of the first drive gear ring  15 , so that, by a rotation of the first pinion  13 , the first drive gear ring  15 , driven by the first drive motor  11 , can be rotated about the rotation axis R. 
     Analogously, the same applies to the second drive gear ring  25 . The second pinion  23  engages by means of its toothing in a toothing of a second intermediate wheel  24 , which, by means of its toothing, engages in a drive toothing of the second drive gear ring  25 , whereby, by a rotation of the second pinion  23 , the second drive gear ring  25 , driven by the second drive motor  21 , can be rotated about the rotation axis R. 
     Between the first and the second drive gear rings  15 ,  25 , a driven gearwheel  32  is arranged, which engages by means of its toothing both in a toothing of the first drive gear ring  15  facing the driven gearwheel  32  and also in a toothing of the second drive gear ring  25  facing the driven gearwheel  32 . The rotation of the driven gearwheel  32  (third rotation) is consequently brought about both by the rotation of the first drive gear ring  15  (first rotation) and also by the rotation of the second drive gear ring  25  (second rotation). 
     From the driven gearwheel  32 , an output shaft  31  connected in a rotationally fixed manner to the driven gearwheel  32  extends along a wheel axis A in the direction of the rotation axis R of the drive gear rings  15 ,  25 . The wheel  30  is connected in a rotationally fixed manner to the output shaft  31  on a side spaced apart from the driven gearwheel  32  along the wheel axis A, whereby a rotation (third rotation) of the driven gearwheel  32  is transmitted via the output shaft  31  to the wheel  30 . The wheel  30 , as represented, is received sectionally between the first drive gear ring  15  and the second drive gear ring  25 , which are spaced apart along their rotation axis R and define a wheel-receiving space  20  between them. The two drive gear rings  15 ,  25  comprise a ring opening  15 ′,  25 ′ extending through the respective drive gear ring  15 ,  25  along the rotation axis R. The wheel  30  extends at least on its side facing the ground B through the respective ring opening  15 ′,  25 ′, whereby the wheel  30  comprises substantially five sections. A first section where the wheel  30  is arranged between the drive gear rings, two second sections where the wheel  30  is arranged in the ring openings  15 ′,  25 ′ of the drive gear rings  15 ,  25 , and two third sections where the wheel  30  is lies along the rotation axis R outside of the drive gear rings  15 ,  25 . The arrangement of the wheel  30  in the wheel-receiving space  20  leads to three advantageous effects. The installation space of the wheel drive module is clearly reduced, since the wheel  30 , during a steering movement, does not have to run around the drive gear rings  15 ,  25 , and the possible steering angle is widened, since the wheel  30  can rotate by 360° in the drive gear rings  15 ,  25  without the steering movement or rotation about the rotation axis R being limited by the intermediate wheels  14 ,  24 . In addition, the wheel  30  is protected by the wheel drive module  1  or by the first and second drive gear rings  15 ,  25 , since they form a cage around the wheel  30 . 
     In comparison to the wheel drive module  1  of  FIG. 1 , the embodiment variant of the wheel drive module  1  represented in  FIG. 2  additionally comprises an intermediate shaft  34 , a driving intermediate wheel  33  and a driven intermediate wheel  35 . The intermediate shaft  34  extends along an intermediate axis Z and can be rotated about it. On a first side, along the intermediate axis Z, the driving intermediate wheel  33 , and on an opposite second side, along the intermediate axis Z, the driven intermediate wheel  35  are fastened or connected to the intermediate shaft  34 . The driving intermediate wheel  33  is designed as a gearwheel and engages in the first and second drive gear rings  15 ,  25 , whereby the intermediate shaft  34  with the driving intermediate wheel  33  and with the driven intermediate wheel  35  can be rotated via the driving intermediate wheel  33  about the intermediate axis Z by the first and second rotations of the drive gear rings  15 ,  25 . The driven intermediate wheel  35  is also designed as gearwheel and engages by means of its toothing in the toothing of the driven gearwheel  32 . The rotation of the intermediate axis Z is transmitted via the driven intermediate wheel  35  to the driven gearwheel  32 , to the output shaft  31  and to the wheel  30 , whereby the wheel  30  can be driven about the wheel axis A. The intermediate axis Z and the wheel axis A are offset or spaced apart from one another along the rotation axis R and, in the present embodiment example, parallel to one another. The ground clearance is thus increased without an increase of the wheel diameter of the wheel  30  and at the same time the design height is furthermore reduced, since a section of the wheel  30  remains arranged between the drive gear rings  15 ,  25 . 
     The wheel drive module  1  represented in  FIG. 3  is depicted in a partial section cut along the rotation axis R. In  FIG. 3 , the wheel  30  or the output shaft  31  is driven, as in the wheel drive module  1  shown in  FIG. 1 , via the driven gearwheel  32  directly by the first and second drive gear rings  15 ,  25  and comprises no intermediate shaft  34 . The output shaft  31  with the driven gearwheel  32  and with the wheel  30  is held on an inner ring  33  which extends along the rotation axis R in the form of a tube through the wheel-receiving space  20 . The inner ring  33  is supported on an outer ring  34  via an outer bearing ring which can be implemented in particular as ball bearings. On the inner ring  33 , the first drive gear ring  15  and the second drive gear ring  25  are mounted in each case via an additional inner bearing ring. 
     Unlike the embodiment as represented in  FIG. 3 , the wheel drive module  1  in  FIG. 4  comprises a cover plate  16  and protective plate  26 . 
     The cover plate  16  is connected to the first drive gear ring  15  by means of diagrammatically indicated screws and can be rotated with it. The cover plate closes the wheel-receiving space  20  on the side of the wheel drive module  1  facing away from ground B, as a result of which no dirt or foreign bodies can penetrate from the side facing away from the ground B into the wheel drive module  1  or into the wheel-receiving space  20 . In addition, no dirt accumulating on the wheel  30 , or introduced from the side of the wheel-receiving space  20  facing the ground B, can penetrate into the assemblies arranged on the side of the wheel drive module  1  facing away from ground B. In an alternative embodiment, not shown, the cover plate  16  can also be fastened on the inner ring  33 , whereby it can be rotated with the wheel  30  about the rotation axis R. If the cover plate  16  is fastened on the inner ring  33 , a force acting on the wheel  30  can moreover be supported via the cover plate  16 . 
     The protective cover plate  16  which is arranged on the side of the wheel drive module  1  facing the ground B, comprises a slot-like protective plate opening  26 ′, through which the wheel  30  extends from the wheel-receiving space  20  to the ground B. Furthermore, protective plate  16  is screwed on the inner ring  33  and can be rotated with it about the rotation axis R. By means of the protective plate  16 , the opening of the wheel drive module  1  or of the wheel-receiving space  20  facing the ground B can be nearly closed, so that substantially no dirt can penetrate into the wheel-receiving space.