Patent Publication Number: US-2022219577-A1

Title: Fitting for vehicle seat

Description:
The invention relates to a joint fitting for a vehicle seat, in particular for a motor vehicle seat, having a first fitting part with a first sprocket, a second fitting part with a second sprocket, the second fitting part being rotatable about an axis of rotation relative to the first sprocket, a gear, which rolls in the first sprocket and in the second sprocket, for generating a rotary movement between the first sprocket and the second sprocket, an eccentric, which is arranged between the first fitting part and the gear, for driving a rolling movement of the gear in the first sprocket, the eccentric having two wedge segments and a spring that pushes the wedge segments apart. The invention also relates to a vehicle seat. 
     PRIOR ART 
     DE 30 13 304 A1 discloses an adjusting device for seats and windows in particular of motor vehicles, having articulated levers that are connected together via a pivot pin, wherein an internal gear is assigned to one articulated lever and a spur gear that meshes in the other articulated lever is assigned to said other articulated lever, the tip circle of said spur gear being at least one tooth height smaller than the root circle of the internal gear, and one of the two articulated levers is mounted on an eccentric connected to the drivable pivot pin in a torque-transmitting manner. The eccentric consists of a driver disk arranged on the pivot pin for conjoint rotation and of two wedge segments which are inclined relative to one another, regionally enclose the driver disk at its periphery, and between which an energy store that pushes the wedge segments apart is arranged. 
     DE 44 36 101 A1 discloses a joint fitting for seats having an adjustable backrest, in particular motor vehicle seats in which a fixed joint part assigned to the sitting part and a pivotable joint part assigned to the backrest are connected together via a pivot pin, wherein an adjusting and fixing device that determines the position of the two joint parts relative to one another and is in the form of a transmission is provided and the pivot pin, for mounting one joint part, has an eccentric portion that is formed from two wedge segments that regionally enclose the pivot pin and are inclined relative to one another, a driver arm that engages between the narrow sides of said wedge segments, and an energy store that pushes the wide sides of the wedge segments apart, wherein the pivot pin of each joint fitting has a central receptacle for connecting, for conjoint rotation, to a transmission rod that couples the two joint fittings of a seat together. The driver is in the form of a bush that is connected integrally to the driver arm integrated into the driver and is connected to a covering disk that engages externally over the joint region. The bush has, in its center, the torque-transmitting receptacle for a transmission rod. 
     DE 10 2005 031 263 A1 discloses a joint fitting for an adjustable vehicle seat, in particular a joint fitting for a backrest of a motor vehicle seat, having a first sprocket, having a second sprocket, wherein the two sprockets are rotatable about an axis with respect to one another and are centered about this axis, and having a drive unit having a shaft for introducing an adjusting movement, wherein the shaft is central with respect to the axis, a central, circular recess which is offset with respect to the axis by a degree of eccentricity, a drive part which is located in the recess, bears against this recess and is rotationally connected to the shaft, and a compensating unit which has a wedge piece connected to the shaft, a mating face that cooperates with this wedge piece and is formed on the drive part, and an elastic means that preloads the drive part such that the drive part is pushed toward the highest point of the wedge piece. 
     The development of autonomously driving vehicles requires an extended setting range of the vehicle seat used by an occupant in charge of the vehicle, in order for it to be possible to increase the comfort for a driver who is no longer constantly steering. This means, while at the same time maintaining occupant safety in the event of an accident, that a seatbelt has to move entirely with the seat in order to bear closely on the occupant even in the case of a vehicle seat arranged far back or of a backrest that has been set into a flat position. Such belt systems, the shoulder belt of which is therefore no longer fastened to the B pillar so as to be fixed to the vehicle body but rather in the upper region of the backrest, result in significantly greater loads in the setting fitting and consequently, while having the same basic mechanical principle, require more installation space and more weight than in the case of setting fittings known from the prior art. 
     Problem 
     The invention is based on the problem of improving a joint fitting of the type mentioned at the beginning, in particular of reducing backlash in the joint fitting, and of providing a corresponding vehicle seat. 
     Solution 
     This problem is solved by a joint fitting for a vehicle seat, in particular for a motor vehicle seat, having a first fitting part with a first sprocket, a second fitting part with a second sprocket, the second fitting part being rotatable about an axis of rotation relative to the first sprocket, a gear, which rolls in the first sprocket and in the second sprocket, for generating a rotary movement between the first sprocket and the second sprocket, an eccentric, which is arranged between the first fitting part and the gear, for driving a rolling movement of the gear in the first sprocket, the eccentric having two wedge segments and a spring that pushes the wedge segments apart, wherein a further eccentric, in particular for eliminating backlash between the gear and the second sprocket, is arranged between the second fitting part and the gear, the further eccentric having two wedge segments. 
     Since a further eccentric, in particular for eliminating backlash between the gear and the second sprocket, is arranged between the second fitting part and the gear, wherein the further eccentric has two wedge segments, a joint fitting with reduced backlash is provided. 
     The two sprockets can have different numbers of teeth from one another. By choosing the difference in the numbers of teeth, the step-down ratio between the two fitting parts, or between the gear, for the one part, and the fitting parts, for the other part, can be set structurally. The difference in the numbers of teeth between the two sprockets can be exactly one. Preferably, the first sprocket has 50 teeth and the second sprocket has 51 teeth. The difference in the numbers of teeth between the two sprockets can be greater than one. 
     The gear preferably has a lower number of teeth than either of the two sprockets. The difference between the number of teeth of the gear and the number of teeth of one of the two sprockets can be exactly one. Preferably, the gear has 49 teeth. The difference in the numbers of teeth between the gear and the two sprockets can also be greater than one in each case, however. 
     The gear can be equipped with a common toothing for both sprockets, said toothing being the same for both sprockets. Alternatively, the gear can be constructed from two different gears that are fixedly connected together and have a different number of teeth, wherein one gear is in mesh with the first sprocket and the other gear is in mesh with the second sprocket. 
     Preferably, the two eccentrics have an identically oriented eccentricity with respect to the axis of rotation. This means that the two eccentrics are not arranged in a skewed manner with respect to one another. In each case two wedge segments can be arranged axially adjacent to one another. The two eccentrics can be arranged axially adjacent to one another. The wedge segments of the two eccentrics can be identical parts. 
     In each case two wedge segments can be arranged mirror-symmetrically to a plane of symmetry extending perpendicularly to the axis of rotation. The two eccentrics can be arranged mirror-symmetrically to a plane of symmetry extending perpendicularly to the axis of rotation. 
     The eccentric can have a spring that pushes its wedge segments apart. Since the spring pushes the wedge segments apart, the gear is in backlash-free mesh with the first sprocket in a radial direction. The further eccentric can also have a spring that pushes its wedge segments apart. Since the spring pushes the wedge segments apart, the gear is also in backlash-free mesh with the second sprocket in a radial direction. 
     The further eccentric can have a driver that drives its wedge segments. A driver arm of the driver can engage between the wedge segments of the eccentric such that, as a result of rotation of the driver, the wedge segments are rotated and as a result drive the gear. 
     The two fitting parts can be fixed axially with respect to one another by a clasp ring. The two fitting parts are then movable to a limited extent in a radial direction with respect to one another, however, in order that radial backlash can be compensated by the eccentric. 
     At least one of the eccentrics can be mounted in a plain bearing bush in order to reduce friction. The plain bearing bush can be arranged in, in particular pressed into, one of the two fitting parts. Preferably, each of the two eccentrics is mounted in a respective plain bearing bush. As a result of the wedge segments being mounted in plain bearings, the load-bearing capacity is improved and the wear in fast mode is reduced. 
     As a result of a disk that is elastically preloaded in a radial direction, additional elimination of backlash between the gear and one of the two sprockets can take place. The disk can exhibit a more resilient material radially on the inside than radially on the outside. A radially outer region of the disk can be produced from a metal, in particular from steel. A radially outer region of the disk can have a slightly greater tip circle radius than the gear. A radially inner region of the disk can be produced from plastic or rubber. 
     The disk can have a toothing radially on the outside. The number of teeth of the toothing on the disk can be equal to the number of teeth of the sprocket with which the disk is in mesh. The toothing on the disk can be in mesh with the first sprocket. Alternatively, the toothing on the disk can be in mesh with the second sprocket. A radially inner region of the disk can be supported on a step of the gear. The step can be circumferential. 
     The problem is also solved by a vehicle seat having at least one joint fitting according to the invention. Preferably, the vehicle seat has a sitting part and a backrest, which is articulated on the sitting part so as be settable about an axis of rotation by the at least one joint fitting. As a result of the use of the joint fitting according to the invention, backlash at an upper edge of the backrest is reduced. 
    
    
     
       FIGURES AND EMBODIMENTS OF THE INVENTION 
       The invention is explained in more detail in the following text by way of advantageous exemplary embodiments illustrated in the figures. The invention is not limited to these exemplary embodiments, however. In the figures: 
         FIG. 1 : shows a schematic view of a vehicle seat according to the invention having a joint fitting according to the invention, 
         FIG. 2 : shows an exploded illustration of a joint fitting according to the invention according to a first exemplary embodiment, 
         FIG. 3 : shows an illustration of the transmission principle of the joint fitting from  FIG. 2 , 
         FIG. 4 : shows a perspective view of the joint fitting from  FIG. 2 , 
         FIG. 5 : shows a side view of the joint fitting from  FIG. 2 , wherein a driver is not illustrated in order to reveal wedge segments of an eccentric of the joint fitting, 
         FIG. 6 : shows a section through the joint fitting from  FIG. 2 , 
         FIG. 7 : shows a front view of the joint fitting from  FIG. 2 , and 
         FIG. 8 : shows a section through a joint fitting according to a second exemplary embodiment. 
     
    
    
       FIG. 1  shows a vehicle seat  1  according to the invention for a motor vehicle. The vehicle seat  1  has a sitting part  3  and a backrest  5  that is settable in terms of its inclination relative to the sitting part  3 . To set the inclination of the backrest  5 , a transmission rod is turned, for example manually by a hand wheel or in a motor-driven manner, for example by an electric motor. The transmission rod is arranged horizontally in the transition region between the sitting part  3  and the backrest  5 . On both sides of the vehicle seat  1 , the transmission rod engages for conjoint rotation in a respective joint fitting  100 ;  200  according to the invention. 
       FIGS. 2 to 7  show a first exemplary embodiment of a joint fitting  100  according to the invention. The joint fitting  100  has a first fitting part  110  and a second fitting part  120 . The second fitting part  120  is rotatable about an axis of rotation A relative to the first fitting part  110 . The direction specifications used in the following text, such as central, axial, radial and circumferential direction, relate to the axis of rotation A. 
     One of the two fitting parts  110 ;  120  is able to be connected for example fixedly to the sitting part  3  and the other of the two fitting parts  110 ;  120  is able to be connected fixedly to the backrest  5 . 
     The first fitting part  110  has a first sprocket  112 . The first fitting part  110  is preferably in the form of a ring gear. The axis of rotation A coincides with a central axis of the first sprocket  112 . Fastened centrally to the first fitting part  110  is a plain bearing bush  114 , which has preferably been pressed into a central opening in the first fitting part  110 . 
     The second fitting part  120  has a second sprocket  122 . The second fitting part  120  is preferably in the form of a ring gear. The axis of rotation A coincides with a central axis of the second sprocket  122 . Fastened centrally to the second fitting part  120  is a bush  126 , in which a plain bearing bush  124  is arranged. Preferably, the plain bearing bush  124  has been pressed into the bush  126  and thus into the second fitting part  120 . 
     A gear  130  serves to drive the rotary movement of the second fitting part  120  about the axis of rotation A relative to the first fitting part  110 . The gear  130  is in the form of an externally toothed gear. It is in mesh with the first internally toothed sprocket  112  and the second internally toothed sprocket  122 . The gear  130  and the internal sprockets  112 ;  122  are configured such that the gear  130  can tumble within the internal sprockets  112 ;  122 . Preferably, the two sprockets have a different number of teeth than one another, in particular a difference in the number of teeth of one. The gear  130  preferably has a lower number of teeth than either of the two sprockets  112 ;  122 . The difference in the numbers of teeth between the gear  130  and one of the two sprockets  112 ;  122  can be exactly one. In the present exemplary embodiment, the first sprocket  112  has fifty teeth, the second sprocket  122  has fifty-one teeth and the gear  130  has forty-nine teeth. 
     The gear  130  has a shaft portion  132 , which protrudes axially on both sides beyond the toothing. The shaft portion  132  is central with respect to the toothing of the gear  130  and tumbles about the axis of rotation A in the driven state. 
     To drive the tumbling rolling movement of the gear  130  in the internal sprockets  112 ;  122  and thus to drive the rotary movement of the second fitting part  120  about the axis of rotation A relative to the first fitting part  110 , exactly one eccentric  160 , also referred to below as first eccentric  160 , is arranged between the shaft portion  132  and the plain bearing bush  114  of the first fitting part  110 . In addition, exactly one further eccentric  180 , also referred to below as second eccentric  180 , is arranged between the shaft portion  132  and the plain bearing bush  124  of the second fitting part  120 . The two eccentrics  160 ;  180  each have, in addition to the driving function, the function of compensating for radial backlash, as is described in more detail below. The two eccentrics  160 ;  180  each correspond, in terms of function and structure, to an eccentric known from DE 44 36 101 A1 and are constructed largely in a mirror-symmetric manner, for which reason only the first eccentric  160  is described in detail. 
     A first driver  162  is mounted in a rotatable manner in the shaft portion  132 . The first driver  162  is preferably made integrally from plastic. The first driver  162  has a hub  163 , which is mounted in a rotatable manner with its outer shell in an end region, facing in the direction of the first fitting part  110 , of the shaft portion  132 . Connected to the hub  163  is a driver arm  164  that engages regionally over the shaft portion  132  and is arranged at a radial distance from the hub  163 . The driver arm  164  and the hub  163  transition into a covering disk  165 , engaging radially over the first eccentric  160 , of the driver  162 . 
     Two wedge segments  166  are supported on the shaft portion  132  with their radially inwardly facing inner faces. The wedge segments  166  have radially outwardly facing outer faces, which are in contact with the inner face of the plain bearing bush  114 . The wedge segments  166  are each arranged approximately in the same axial plane as the toothing of the first sprocket  112 . 
     Each of the two wedge segments  166  has two end faces that are largely perpendicular to the circumferential direction. As seen in the circumferential direction, the two wedge segments  166  are mirror-symmetric to one another. Each of the two wedge segments  166  has, as seen in a radial direction, a narrow end face and a wide end face. The wide end faces of the wedge segments  166  are preloaded away from one another by a spring  168 , in the present case a spring  168  in the form of an annular spring. 
     The wedge segments  166  form, together with the shaft portion  132 , an eccentric portion with an eccentricity e with respect to the axis of rotation A. The eccentric portion is a constituent of the first eccentric  160  and pushes the gear  130  and the first sprocket  112  into mesh with one another. By way of the spring  168 , the two wedge segments  166  are preloaded away from one another such that, on account of a wedge effect, the gear  130  and the first sprocket  112  mesh in one another without backlash, such that the first eccentric  160  also provides radial backlash compensation between the first sprocket  112  and the gear  130 . 
     The driver arm  164  engages with slight play between the wide end faces of the wedge segments  166 , such that rotation of the driver  162 , after a slight inoperative angle, causes the first eccentric  160  to rotate. 
     The hub  163  of the driver  162  has, in its center, a bore with a splined shaft profile, in which a complementary splined shaft profile of a transmission rod (not illustrated in the figures) meshes. The transmission rod is able to be driven manually or by an electric motor. A rotation of the transmission rod causes the first driver  162  and, as described in more detail below, a second driver  182  to rotate. In addition, the transmission rod can drive a second joint fitting of the vehicle seat synchronously with the joint fitting  100 . 
     The second driver  182  is likewise mounted in a rotatable manner in the shaft portion  132 . The second driver  182  has a hub  183 , which is mounted in a rotatable manner with its outer shell in an end region, facing in the direction of the second fitting part  120 , of the shaft portion  132 . Connected to the hub  183  is a driver arm  184 . Connected to the hub  183  is a driver arm  184  that engages regionally over the shaft portion  132  and is arranged at a radial distance from the hub  183 . The driver arm  184  and the hub  183  transition into a covering disk  185 , engaging radially over the first eccentric  180 , of the driver  182 . 
     Two wedge segments  186  of the second eccentric  180  are supported on the shaft portion  132  with their radially inwardly facing inner faces. The wedge segments  186  have radially outwardly facing outer faces, which are in contact with the inner face of the plain bearing bush  124  of the second fitting part  120 . The wedge segments  186  are each arranged approximately in the same axial plane as the toothing of the second sprocket  122 . 
     The wedge segments  186  are preloaded away from one another by a spring  188 . The wedge segments  186  form, together with the shaft portion  132 , an eccentric portion with an eccentricity e with respect to the axis of rotation A, which is oriented in the same direction as the eccentricity e of the first eccentric  160 . The eccentric portion is a constituent of the second eccentric  180  and pushes the second sprocket  122  and the gear  130  into mesh with one another. By way of the spring  188 , the two wedge segments  186  are preloaded away from one another such that, on account of a wedge effect, the second sprocket  122  and the gear  130  mesh in one another without backlash such that the second eccentric  180  also provides radial backlash compensation between the second sprocket  122  and the gear  130 . 
     The driver arm  184  engages with slight play between the wide end faces of the wedge segments  186 , such that a rotation of the second driver  182 , after a slight inoperative angle, causes the eccentric  180  to rotate. 
     The hub  183  of the driver  182  has, in its center, a bore with a splined shaft profile, in which the complementary splined shaft profile of the transmission rod meshes. A rotation of the transmission rod therefore also causes the second driver  182  to rotate. 
     The two fitting parts  110 ;  120  are fixed axially with respect to one another by a clasp ring  190 , wherein the two fitting parts  110 ;  120  are movable to a limited extent in a radial direction with respect to one another. The function of a clasp ring is known per se, for example from DE 10 2010 013 092 A1. 
       FIG. 8  shows a section through a joint fitting  200  according to a second exemplary embodiment, which corresponds in terms of structure and function to the above-described joint fitting  100  of the first exemplary embodiment, unless described otherwise below. 
     The joint fitting  200  has a first fitting part  210  and a second fitting part  220 . The second fitting part  220  is rotatable about an axis of rotation A relative to the first fitting part  210 . 
     The first fitting part  210  has a first sprocket  212 . The axis of rotation A coincides with a central axis of the first sprocket  212 . A plain bearing bush  214  has been pressed centrally into the first fitting part  210 . The second fitting part  220  has a second sprocket  222 . The axis of rotation A coincides with a central axis of the second sprocket  222 . A plain bearing bush  224  has been pressed centrally into the second fitting part  220 . 
     A gear  230  serves to drive the rotary movement of the second fitting part  220  about the axis of rotation A relative to the first fitting part  210 . The gear  230  is in mesh with the first internally toothed sprocket  212  and the second internally toothed sprocket  222 . The gear  230  can tumble within the internal sprockets  212 ;  222 . 
     The gear  230  has a shaft portion  232 , which protrudes axially on both sides beyond the toothing. The shaft portion  232  is central with respect to the toothing of the gear  230  and tumbles about the axis of rotation A in the driven state. 
     To drive the tumbling rolling movement of the gear  230  in the internal sprockets  212 ;  222  and therefore to drive the rotary movement of the second fitting part  220  about the axis of rotation A relative to the first fitting part  210 , exactly one eccentric  260 , also referred to below as first eccentric  260 , is arranged between the shaft portion  232  and the plain bearing bush  214  of the first fitting part  210 . In addition, exactly one further eccentric  280 , also referred to below as second eccentric  280 , is arranged between the shaft portion  232  and the plain bearing bush  224  of the second fitting part  220 . The two eccentrics  260 ;  280  each have, in addition to the driving function, the function of radial backlash compensation, as described above. 
     A first driver  262  is mounted in a rotatable manner in the shaft portion  232 . The first driver  262  has a hub  263 , which is mounted in a rotatable manner in the shaft portion  232 . A driver arm is connected to the hub  263 . 
     Two wedge segments  266  are supported on the shaft portion  232  with their radially inwardly facing inner faces. The wedge segments  266  have radially outwardly facing outer faces, which are in contact with the inner face of the plain bearing bush  214 . Each of the two wedge segments  266  has two end faces that are largely perpendicular to the circumferential direction. As seen in the circumferential direction, the two wedge segments  266  are mirror-symmetric to one another. The wedge segments  266  are preloaded away from one another by a spring  268 . 
     The wedge segments  266  form, together with the shaft portion  232 , an eccentric portion with an eccentricity e with respect to the axis of rotation A. The eccentric portion is a constituent of the first eccentric  260  and pushes the gear  230  and the first sprocket  212  into mesh with one another. By way of the spring  268 , the two wedge segments  266  are preloaded away from one another such that, on account of a wedge effect, the gear  230  and the first sprocket  212  mesh in one another without backlash, such that the first eccentric  260  also provides radial backlash compensation between the first sprocket  212  and the gear  230 . 
     In addition to the first eccentric  260 , a disk  270  elastically preloaded in a radial direction provides radial backlash compensation between the first sprocket  212  and the gear  230 . The disk  270  can exhibit a more resilient material radially on the inside than radially on the outside. A radially outer region of the disk  270  can be produced from a metal. A radially inner region of the disk  270  can be produced from a plastic. 
     The disk  270  has a toothing radially on the outside. The number of teeth of the toothing on the disk  270  is equal to the number of teeth of the first sprocket  212 , with which the disk  270  is in mesh. The toothing of the disk  270  can be in mesh with the first sprocket  212 . A radially inner region of the disk  270  is supported on an axial step of the gear  230 . The toothing of the disk  270  protrudes radially slightly beyond the toothing of the gear  230 . As a result, the toothing of the disk  270  is radially preloaded, with the result that the disk  270  provides radial backlash compensation between the first sprocket  212  and the gear  230 . 
     The driver arm engages with slight play between the wide end faces of the wedge segments  266 , such that a rotation of the driver  262 , after a slight inoperative angle, causes the first eccentric  260  to rotate. 
     The hub  263  of the first driver  262  has, in its center, a bore with a splined shaft profile, in which a complementary splined shaft profile of a transmission rod (not illustrated in the figures) meshes. A rotation of the transmission rod causes the first driver  262  and, as described in more detail below, a second driver  282  to rotate. 
     The second driver  282  is likewise mounted in a rotatable manner in the shaft portion  232 . The second driver  282  has a hub  283 , which is mounted in a rotatable manner in the shaft portion  232 . A driver arm is connected to the hub  283 . 
     Two wedge segments  286  of the second eccentric  280  are supported on the shaft portion  232  with their radially inwardly facing inner faces. The wedge segments  286  have radially outwardly facing outer faces, which are in contact with the inner face of the plain bearing bush  224  of the second fitting part  220 . 
     The wedge segments  286  are preloaded away from one another by a spring  288 . The wedge segments  286  form, together with the shaft portion  232 , an eccentric portion with an eccentricity e with respect to the axis of rotation A, which is oriented in the same direction as the eccentricity e of the first eccentric  260 . The eccentric portion is a constituent of the second eccentric  280  and pushes the second sprocket  222  and the gear  230  into mesh with one another. By way of the spring  288 , the two wedge segments  286  are preloaded away from one another such that, on account of a wedge effect, the second sprocket  222  and the gear  230  mesh in one another without backlash, such that the second eccentric  280  also provides radial backlash compensation between the second sprocket  222  and the gear  230 . 
     The driver arm engages with slight play between the wide end faces of the wedge segments  286 , such that a rotation of the second driver  282 , after a slight inoperative angle, causes the second eccentric  280  to rotate. 
     The hub  283  of the driver  282  has, in its center, a bore with a splined shaft profile, in which the complementary splined shaft profile of the transmission rod meshes. A rotation of the transmission rod therefore also causes the second driver  282  to rotate. 
     The two fitting parts  210 ;  220  are fixed axially with respect to one another by a clasp ring  290 , wherein the two fitting parts  210 ;  220  are movable to a limited extent in a radial direction with respect to one another. 
     The features disclosed in the above description, the claims and the figures can be of significance both on their own and in combination for implementing the invention in their various configurations, as long as they remain within the scope of protection of the claims. 
     Terms such as “comprise”, “have”, “contain”, “include” and the like that are used in the claims do not exclude further elements or steps. The use of the indefinite article does not exclude a plurality. An individual device can carry out the functions of a plurality of units or devices mentioned in the claims. 
     LIST OF REFERENCE SIGNS 
     
         
           100  Joint fitting 
           110  First fitting part 
           112  First sprocket 
           114  Plain bearing bush 
           120  Second fitting part 
           122  Second sprocket 
           124  Plain bearing bush 
           126  Bush 
           130  Gear 
           132  Shaft portion 
           160  Eccentric 
           162  Driver 
           163  Hub 
           164  Driver arm 
           165  Covering disk 
           166  Wedge segment 
           168  Spring 
           180  Eccentric 
           182  Driver 
           183  Hub 
           184  Driver arm 
           185  Covering disk 
           186  Wedge segment 
           188  Spring 
           190  Clasp ring 
           200  Joint fitting 
           210  First fitting part 
           212  First sprocket 
           214  Plain bearing bush 
           220  Second fitting part 
           222  Second sprocket 
           224  Plain bearing bush 
           226  Bush 
           230  Gear 
           232  Shaft portion 
           260  Eccentric 
           262  Driver 
           263  Hub 
           266  Wedge segment 
           268  Spring 
           270  Disk 
           280  Eccentric 
           282  Driver 
           283  Hub 
           286  Wedge segment 
           288  Spring 
           290  Clasp ring 
         A Axis of rotation 
         e Eccentricity