Patent Abstract:
A shifting device including at least one coupling device, a shaft, a sliding sleeve-of the coupling device which is arranged in an axially moveable and rotationally fixed manner on the shaft and an actuator arrangement of the coupling device for axially moving the sliding sleeve. At least one coupling toothing is associated with the coupling element which can rotate about a rotational axis with respect to the shaft and a counter toothing corresponding to the coupling toothing is associated with the sliding sleeve in a rotationally fixed manner. At least one annular actuator element of the actuator arrangement surrounds the periphery of the sliding sleeve about the rotational axis.

Full Description:
The present invention relates to a shifting device which has at least one coupling device, a shaft, a shifting collar of the coupling device which is situated in an axially shiftable and rotatably fixed manner on the shaft and an actuator system of the coupling device for axially shifting the shifting collar, at least one coupling toothing being assigned to the coupling element, which is able to rotate around a rotation axis relative to the shaft, and at least one mating toothing corresponding to the coupling toothing being rotatably fixedly assigned to the shifting collar, and at least one annular actuator element of the actuator system surrounding the shifting collar around the rotation axis on the circumferential side. 
     BACKGROUND 
     EP 1977130 B1 shows a shifting device of this type. The shifting device has a coupling element which is rotatably supported on the shaft relative to the shaft. The coupling element should be rotatably fixedly connected to the shaft via the shifting collar upon engagement of a gear and be able to rotate again relative to the shaft upon changing gears. For this purpose, the shifting collar is situated on the shaft in an axially shiftable and rotatably fixed manner and therefore is shiftably supported on a hub which is fixedly connected to the shaft. 
     The rotatably fixed, detachable connection between the shifting collar and the coupling element is implemented with the aid of tooth engagement. For this purpose, a coupling toothing, which corresponds to a mating toothing on the shifting collar, is provided on the coupling element. The teeth of the toothings and the tooth gaps are longitudinally oriented, so that when a gear is engaged, the teeth of the mating toothing are insertable into the tooth gaps of the coupling toothing until the teeth of the toothings are alternately opposite each other in the circumferential direction and are thus rotatably fixedly coupled. An electromagnetic actuator system for actuating the shifting collar or an annular element of the actuator system surrounds the shifting collar on the circumferential side, so that the shifting device may have a very compact design. 
     Coupling elements may be, for example, gear wheels, so-called idler gears, on which the coupling toothing is provided directly. Alternatively the coupling elements are coupling members having the coupling toothing which are rotatably fixedly coupled with a gear wheel. 
     The installation space required by a shifting device of this type is dependent on the radial and axial dimensions of the coupling element and the shifting collar. The dimensions of the electromagnetic actuator are dependent on the forces needed for shifting. The installation space required by the shifting device is therefore essentially also influenced by the size of the actuator system and may therefore be large if a great deal of power is required. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a shifting device in which the installation space required is largely independent of the shifting forces. 
     The present invention provides that the annular actuator element is at least one gear shift drum. A gear shift drum is understood to be a component of a partially hollow cylindrical design or a completely hollow cylindrical design which is preferably made of sheet metal. 
     The gear shift drum has at least one guideway but may also have two or more guideways. The guideways are, for example, grooves which are introduced into the gear shift drum. These grooves radially penetrate the wall of the gear shift drum or have a closed groove base. In gear shift drums made of sheet metal, the guideways are punched or rolled in. Punched guideways extend beyond a partial circumference and are provided on gear shift drums which are pivotable around the pivot axis. The pivot axis corresponds to the rotation axis of the coupling element. Rolled-in guideways extend beyond a partial circumference and are provided on pivotable gear shift drums. Alternatively, the rolled-in guideways run around the entire circumference, so that they may also be used on rotating gear shift drums. 
     Alternatively, the guideways are rail-like structures which are mounted radially on the inner circumference of the gear shift drum or which project from the inner circumferential surface of the gear shift drum and which are provided with a simple I-shaped or U-shaped design in any longitudinal sections along the rotation axis and whose legs project radially to the inside. 
     Mounted or projecting guideways extend beyond a partial circumference and are provided on pivotable gear shift drums. Alternatively, the mounted or projecting guideways run around the entire circumference, so that they may also be used on rotating gear shift drums. 
     The guideways are essentially oriented in the circumferential direction of the gear shift drum, i.e., also in the circumferential direction around the rotation or pivot axis, but they do not run on a circumferential line but are deflected from an imaginary circumferential line in axial directions, optionally run back in the axial direction, etc. This course is dependent on the shifting times and the axial lift to be covered by the shifting collar. 
     A guiding element is coupled with the shifting collar in such a way that the shifting collar is rotatable around the rotation axis relative to the guiding element but may be entrained by the guiding element in the axial direction. The guiding element radially engages with the particular guideway. The gear shift drum having the guideway is movable relative to the guiding element, so that the guiding element is positively moved axially in a pivoted or rotating guideway and axially entrains the shifting collar. 
     The pivot or rotary drive of the gear shift drum is integrated, for example, into the gear shift drum and is preferably electromotive. However, the drive of the gear shift drum is preferably situated outside the gear shift drum. The latter approach has the advantage that a coupling device may be concentrically integrated into the gear shift drum, as provided by one embodiment of the present invention. In this case, the gear shift drum itself takes up only the radial installation space, which is determined by the wall thickness of its hollow cylinder and the height of any projecting guideways. The dimensions of the annular actuator element are thus essentially independent of the shifting forces. In this case, the gear shift drum may be connected to the drive by a geared connection. Geared connections are belt or chain drives or gear stages. One element, for example a gear wheel or a pulley, is attached to the gear shift drum. Alternatively, this element is integrated into a gear shift drum as a single piece, for example as a toothing on a spur wheel section. 
     One embodiment of the present invention provides that the gear shift drum has a radial flange which projects radially beyond the circumference of the gear shift drum. At least one element of the geared connection is attached to or formed on this flange. The flange is optionally also used for the pivotable or rotatable support of the gear shift drum in relation to the surrounding structure. 
     Other embodiments of the present invention relate to a shifting device in which the coupling device is at least partially concentrically situated within the gear shift drum. The coupling device has the shifting collar and at least one coupling member, preferably two coupling members. In the latter case, the shifting collar has a dual-action design and is mounted axially between the two coupling members. The coupling toothing is provided on each coupling member. 
     The shifting collar is axially shiftably positioned either directly on a shaft or on a hub which is formed with the shaft or is attached thereto. The sliding seat in both cases is supported on a sliding or rolling bearing with the aid of splines or other suitable profiles. 
     One embodiment of the present invention provides that one or multiple locking elements is/are situated radially between the hub and the shifting collar. The locking element(s) is/are made of at least one spring and one bolt pretensioned by the spring, alternatively having a pretensioned ball. The locking element is guided or held in the hub and supported radially against the spring forces. The ball or the locking bolts interlock with trough-shaped indentations when the gears are engaged or in the neutral position and thereby hold the shifting collar in the desired position relative to the shaft. 
     One embodiment of the present invention provides that the coupling device has at least one friction surface which is torsionally fixedly coupled with the shaft but is able to be shifted axially relative to the shaft with the aid of the shifting collar. The friction surface is shiftable on a mating friction surface which is torsionally fixedly coupled with the coupling element and corresponds to the friction surface. The friction surfaces are provided on separate friction members. One of the friction members is torsionally fixedly coupled with the shaft and may be axially shifted by the shifting collar. The other friction member is rotatably fixedly coupled with the coupling member. Alternatively, the friction surfaces are provided directly on the shifting collar or the coupling member. The shaft and the particular coupling member may be braked against each other with the aid of a friction coupling of this type between the shaft and the particular coupling member until the rotational speeds are synchronous. As in the case of synchronous couplings, the engagement of the particular gear is comfortable with the aid of an arrangement of this type. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an electromotively driven drive unit  1  in a longitudinal sectional view along its main axis  18 , drive unit  1  including an electric machine  19  and a transmission  55 . 
         FIG. 2  shows the shifting device  56  in an overall view including drive  23  and geared connection  24 . 
         FIG. 3  shows coupling device  58  in a longitudinal sectional view along main axis  18  according to  FIG. 2 . 
         FIGS. 4 and 5  shows a shifting device  56  which essentially corresponds to shifting device  56  described in  FIGS. 2 and 3 , whose actuator system  79 , is provided with modifications of drive  23  and geared connection  24 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1 : Coupling device  25  has a gear shift drum  22 , coupling elements  26 ,  28  and  30 , a shifting collar  97  and a guiding element  42 . Shifting collar  97  is mounted in an axially shiftable and rotatably fixed manner on coupling element  26 , which is designed as a hub  2 . Hub  2  is rotatably fixedly situated on a shaft  3  which is part of connecting shaft  67  of planetary gear  59  and to which an annulus gear  64  of planetary gear  59  is connected. Actuator system  6  of coupling device  58  is illustrated in its entirety in  FIG. 2 . 
     Coupling element  28  is rotatably situated on a rotor shaft  29  of electric machine  19  around rotation axis  18 ′ on main axis  18  relative to shaft  3  and has a coupling toothing  4 . Coupling element  30  is fixed on a housing  39 ; however, shaft  3  is able to rotate around rotation axis  18 ′ relative to coupling element  30 . Coupling element  30  is provided with a coupling toothing  5 . Shifting collar  97  has a mating toothing  7  and  8  on each side in the axial direction. Toothings  7  and  8  correspond to particular coupling toothings  4  and  5 , which are located axially opposite each other. 
     The annular actuator element designed as gear shift drum  22  is hollow cylindrical and surrounds shifting collar  97  and coupling elements  26 ,  28  and  30 , running around rotation axis  18 ′ on the circumferential side. 
       FIGS. 2 and 3 : As is apparent, in particular, from  FIGS. 2 and 3 , gear shift drum  22  has a hollow cylindrical section  9  and a radial flange  10 . Hollow cylindrical section  9  and radial flange  10  form a single piece with each other. Guideways  41  are provided in section  9 . However, each of guideways  41  is essentially not aligned with a circumferential line but is deflected axially to the left and right. As a result, particular guideway  41  has a curve-shaped course. 
     Particular guiding element  42 , which engages with one of guideways  41 , is fixedly inserted into an outer bearing ring  11 . Outer bearing ring  11  is a component of a rolling bearing  12 , which furthermore includes an inner bearing ring  14  and rolling members  13 . Rolling members  13  are balls and are radially situated between inner and outer bearing rings  14  and  11 . Inner bearing ring  14  is fixedly mounted on shifting collar  97 . An axially fixed connection is established between shifting collar  97  and gear shift drum  22  via guiding elements  42  engaging with guideways  41  and rolling bearing  12  in such a way that shifting collar  97  is axially entrained when gear shift drum  22  pivots around rotation axis  18 ′. However, shifting collar  97  is movable relative to gear shift drum  22  due to rolling bearing  12 . 
     Shifting collar  97  is axially shiftably connected to hub  2  via a spline or similar shaft-hub connections and, according to the representation in  FIG. 3 , it is in a neutral position between toothings  4  and  5  on coupling elements  28  and  30  designed as coupling members  16  and  17 . A locking element  15  is accommodated in hub  2 . Locking element  15  is radially pretensioned against shifting collar  97  by a screw spring and interlocked in an indentation  20  in shifting collar  97 . 
     Coupling device  58  has friction members  25  and  43  which are torsionally fixedly coupled with hub  2  but are axially shiftable in relation to hub  2  with the aid of shifting collar  97 . An inner conical friction surface  44  or  45  is provided on each of friction members  25  and  43 . An outer conical mating friction surface  21  or  46  for particular friction surface  44  or  45  is provided on each of coupling members  16  and  17 . Friction surface  44  may be frictionally engaged with mating friction surface  21  and friction surface  45  may be frictionally engaged with mating friction surface  46  by axially shifting shifting collar  97 . 
     Actuator system  6  has an electric motor  80  as drive  23  which is situated in parallel to electric machine  19 . A geared connection  24  is formed by an intermediate shaft  47  and two gear stages  48  and  49 . Gear stage  48  has a pinion  50 , which is provided on pivot shaft  51  of electric motor  80 , and a spur wheel  52  on intermediate shaft  47 , which are in tooth engagement with each other. Gear stage  49  is provided with a pinion  53 , which is provided on intermediate shaft  47  and which is in tooth engagement with a tooth segment  54 . Tooth segment  54  is provided on flange  10  or is alternatively attached thereto. 
       FIGS. 1 and 3 : Flange  10  is rotatably supported on surrounding structure  63  with the aid of two rolling bearings  60  and  62  in a pivotable manner around rotation axis  18 ′. Surrounding structure  63  includes an end shield  66  and an intermediate wall  68  which are fixed to housing  39 . End shield  66  separates an inner chamber of electric machine  19 , which includes stator  40  and rotor  38 , and rotor shaft  29  from coupling device  58 . Rotor shaft  29  is also supported on end shield  66 . Coupling device  58  and planetary gear  59  are separated from each other by intermediate wall  68 . 
       FIG. 3 : Rolling bearing  60  has a track  69 , oriented in the circumferential direction, which is provided directly in flange  10 , e.g., by embossing in flange  10 . Another track  70  is provided in a mirror-image configuration in intermediate wall  68 . Rolling bearing  62  has a track  71 , oriented in the circumferential direction, which is provided directly in flange  10 . A track  72 , which is provided on a spring element  73 , is provided in a mirror-image configuration in relation to track  71 . Multiple balls  77  are situated between tracks  69  and  70  as rolling members. 
     Spring element  73  is either attached to or at least axially supported on end shield  66 . The rolling bearing arrangement is axially pretensioned between end shield  66  and intermediate wall  68  with the aid of elastically resilient spring element  73 . Tracks  69 ,  70 ,  71  and  72  either run as circular tracks around the entire circumference or are circular arc segment tracks whose arc angle corresponds to the maximum pivot angle of gear shift drum  22 . In the latter arrangement, at least two of the same circular arc segment tracks are situated on the circumferential side. Tracks  69 ,  70 ,  71  and  72  are also designed as ball grooves/track grooves which form a trough adapted to balls  77  in the longitudinal sectional view. 
     Tracks  69  and  70  are radially offset in relation to tracks  71  and  72 . The one track  69  is provided on the one axially oriented front face  74  of flange  10 , and the other track  71  is provided on a front face  75  of flange  10  which is oriented in the opposite direction from front face  74 . Due to an offset  76  in flange  10 , which is provided radially between tracks  69 , and due to the trough-shaped molding of the track grooves in the longitudinal sectional view, the ball grooves touch a shared imaginary radial plane  78  at their axially lowest point, radial plane  78  being axially penetrated perpendicularly by rotation axis  18 ′ and therefore intersecting both tracks  71  and  72  in the groove base. As a result, the roller bearing arrangement requires less axial installation space. 
       FIGS. 4 and 5  shows a shifting device  56  which essentially corresponds to shifting device  56  described in  FIGS. 2 and 3 , whose actuator system  79 , however, is provided with modifications of drive  23  and geared connection  24 . Electric motor  90  of actuator system  79  has a pivot shaft  81  on which a pinion  82  is provided. Pinion  82  is in tooth engagement with a reversing gear wheel  83 , which is rotatably supported on an intermediate shaft  84  with the aid of a hub  185 . Intermediate shaft  84  is fixed to an intermediate wall  85 . 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 List of Reference Numerals 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 Drive unit 
               
               
                 2 
                 Hub 
               
               
                 3 
                 Shaft 
               
               
                 4 
                 Coupling toothing 
               
               
                 5 
                 Coupling toothing 
               
               
                 6 
                 Actuator system 
               
               
                 7 
                 Mating toothing 
               
               
                 8 
                 Mating toothing 
               
               
                 9 
                 Hollow cylindrical section 
               
               
                 10 
                 Flange 
               
               
                 11 
                 Outer bearing ring 
               
               
                 12 
                 Rolling bearing 
               
               
                 13 
                 Rolling member 
               
               
                 14 
                 Inner bearing ring 
               
               
                 15 
                 Locking element 
               
               
                 16 
                 Coupling member 
               
               
                 17 
                 Coupling member 
               
               
                 18 
                 Main axis 
               
               
                 19 
                 Electric machine 
               
               
                 20 
                 Indentation 
               
               
                 21 
                 Mating friction surface 
               
               
                 22 
                 Gear shift drum 
               
               
                 23 
                 Drive for gear shift drum 
               
               
                 24 
                 Geared connection 
               
               
                 25 
                 Friction member 
               
               
                 26 
                 Coupling element 
               
               
                 27 
                 Output shaft 
               
               
                 28 
                 Coupling element 
               
               
                 29 
                 Rotor shaft 
               
               
                 30 
                 Coupling element 
               
               
                 39 
                 Housing 
               
               
                 40 
                 Stator 
               
               
                 41 
                 Guideway 
               
               
                 42 
                 Guiding element 
               
               
                 43 
                 Friction member 
               
               
                 44 
                 Friction surface 
               
               
                 45 
                 Friction surface 
               
               
                 46 
                 Mating friction surface 
               
               
                 47 
                 Intermediate shaft 
               
               
                 48 
                 Gear stage 
               
               
                 49 
                 Gear stage 
               
               
                 50 
                 Pinion 
               
               
                 51 
                 Pivot shaft 
               
               
                 52 
                 Spur wheel 
               
               
                 53 
                 Pinion 
               
               
                 54 
                 Tooth segment 
               
               
                 55 
                 Transmission 
               
               
                 56 
                 Shifting device 
               
               
                 57 
                 Geared connection 
               
               
                 58 
                 Coupling device 
               
               
                 59 
                 Planetary gear 
               
               
                 60 
                 Rolling bearing 
               
               
                 61 
                 Sun wheel 
               
               
                 62 
                 Rolling bearing 
               
               
                 63 
                 Surrounding structure 
               
               
                 64 
                 Annulus gear 
               
               
                 65 
                 Connecting shaft 
               
               
                 66 
                 End shield 
               
               
                 67 
                 Connecting shaft 
               
               
                 68 
                 Intermediate wall 
               
               
                 69 
                 Track 
               
               
                 70 
                 Track 
               
               
                 71 
                 Track 
               
               
                 72 
                 Track 
               
               
                 73 
                 Spring element 
               
               
                 74 
                 Front face 
               
               
                 75 
                 Front face 
               
               
                 76 
                 Offset 
               
               
                 77 
                 Balls 
               
               
                 78 
                 Radial plane 
               
               
                 79 
                 Actuator system 
               
               
                 80 
                 Electric motor 
               
               
                 81 
                 Pivot shaft 
               
               
                 82 
                 Pinion 
               
               
                 83 
                 Reversing gear wheel 
               
               
                 84 
                 Intermediate shaft 
               
               
                 85 
                 Intermediate wall 
               
               
                 86-89 
               
               
                 90 
                 Electric motor 
               
               
                 91-96 
               
               
                 97 
                 Shifting collar

Technology Classification (CPC): 5