Abstract:
A crank-CVT transmission which has a freewheel device connected to an output shaft of the transmission. The device selectively enables and blocks a relative rotation between the device and the output shaft. The transmission further has a switching unit adapted to switch the device and an internal shaft, which can be connected to the output shaft and by a connecting element to a differential. The internal shaft can be displaced in the axial direction of the output shaft. The transmission further has an actuator interacting with the switching unit and adapted to initiate the switch of the device. The actuator has a first mechanism adapted to displace the internal shaft in the axial direction, disconnecting the internal shaft from the differential a second mechanism adapted to drive the switching unit. The second mechanism is coupled to the first mechanism and is driven after the first mechanism.

Description:
This application is a Continuation of PCT/DE2009/001311 filed Sep. 17, 2009, which in turn claims the priority of DE 10 2008 050 282.0 filed Oct. 2, 2008, the priority of both applications is hereby claimed and both applications are incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The present application relates to a crank-CVT transmission. In particular, the invention relates to an actuator which initiates the shifting of freewheels of a crank-CVT transmission. 
     BACKGROUND OF THE INVENTION 
     A crank-CVT transmission is known, for example, from DE 102 43 533 A1. This transmission has a driving shaft, for example a transmission input shaft, which can be coupled to an engine, and at least one driven shaft, for example a transmission output shaft, which shafts can have a drive connection to one another. Furthermore, this transmission has a freewheel device. In this context, the freewheel device is composed of a plurality of freewheel units which are arranged axially one behind the other around the driven shaft and which can be shifted. This means that the blocking direction of the clamping bodies with respect to the two rings which can be rotated with respect to one another can be shifted. By using such freewheel units it is easily possible to change the direction of rotation of the shaft in the transmission and therefore implement, for example, a reverse gear speed. Additional direction shifting transmissions, for example planetary gear mechanisms, are not necessary. 
     In order to shift the blocking function of the freewheel, in DE 102 43 533 A1 a shifting device is provided which has a plurality of shifting units which are each arranged between adjacent clamping bodies. The shifting units can be activated synchronously and have shifting means which each have a rotatable, disk-shaped region and a profiled region, which is preferably composed of a profiled rod. A spring, which is formed by a leg spring, is provided on the profiled region. The spring can be clamped between the profiled region and a clamping body. The profiled rods and the means of activating the shifting can extend axially through all the freewheel units, with the result that when the profiled rods are rotated all the freewheel devices can be shifted at the same time in order to be able to shift the freewheels of a crank-CVT transmission so as to change the direction of travel of a vehicle, the crank-CVT transmission must be load-free. For this reason, the output unit of the crank-CVT transmission must be decoupled from the differential. In previously known crank-CVT transmissions, decoupling or unlocking of the output unit and the activation of the shifting are carried out by means of multi-disk clutches or by means of a plurality of shifting sleeves. In this context, the multi-disk clutches or the shifting sleeves have the function of actuators. 
     The unlocking or decoupling of the output unit by means of multi-disk clutches or shifting sleeves has the disadvantage that a multiplicity of actuators is often also necessary for a multiplicity of freewheels. A multiplicity of actuators requires a relatively large amount of installation space for the crank-CVT transmission. This means that as the number of actuators increases there is an accompanying increase in the space required in the crank-CVT transmission. In addition, the decoupling process has to be matched chronologically to the shifting process by a suitable controller. 
     On this basis, the object of the invention is to provide a crank-CVT transmission which has a single actuator for decoupling the drive unit and for initiating the shifting of the freewheel. 
     SUMMARY OF THE INVENTION 
     The invention is based on the idea of making available the decoupling of the output unit of a crank-CVT transmission and the initiation of the shifting of the freewheels with a single actuator. In this context, the decoupling of the output unit is carried out by means of a first mechanism, and the initiation of the shifting of the freewheels is carried out by means of a second mechanism, the methods of operation of said mechanisms being matched to one another. In order to decouple the output unit, a connecting means which is arranged on an inner shaft, which is in turn connected to an output shaft and which forms a connecting element between the output unit and the differential, is disconnected from the differential by being moved out of engagement. 
     In this context, a crank-CVT transmission contains a freewheel device connected to an output shaft of the transmission, which freewheel device is adapted to optionally enable and to block a relative rotation between the freewheel device and the output shaft. Furthermore, the crank-CVT transmission contains a shifting unit which is adapted to shift the freewheel device, and an inner shaft which can be connected to the output shaft, and to a differential via a connecting means. The inner shaft can be displaced in the axial direction of the output shaft. The crank-CVT transmission also has an actuator which interacts with the shifting unit and is adapted to initiate the shifting of the freewheel device. In this context, the actuator has a first mechanism which is adapted to displace the inner shaft in the axial direction in order to disconnect the inner shaft from the differential, and a second mechanism which is adapted to drive the shifting unit. In this context, the second mechanism is coupled to the first mechanism and is driven after the first mechanism in terms of time. 
     The decoupling of the output unit is preferably carried out by, for example, de-meshing the connecting means using a ramp mechanism. In this context, the ramp mechanism has ramp bodies in the form of halls or rollers. The ramp mechanism is activated by means of a first planetary gear set. The freewheels are shifted by means of two further planetary gear sets. 
     The three planetary gear sets preferably have a common web and therefore a common planetary gear carrier. The shifting of the freewheels is matched chronologically to the decoupling of the output unit by means of the common planetary gear carrier and a suitable connection between the first and second mechanisms. 
     This means that in accordance with the basic idea of the invention the shifting process of the freewheels is carried out on the basis of the progress of the decoupling process of the output unit, and is matched thereto. The shifting of the freewheels does not take place until the decoupling of the connecting means is terminated and the output unit is load-free. Incorrect control can be avoided by virtue of the preferably mechanical interaction between the shifting process and the decoupling process. A reliable operational sequence of the crank-CVT transmission which simultaneously requires little installation space is therefore made possible. 
     The connecting means can preferably correspond to a bevel gear. The shifting unit can be a spindle unit or some other shifting mechanism. 
     During the relieving of the loading on the drive unit by means of the first mechanism, the drive unit is placed in a load-free state in terms of the coupling to the differential. 
     According to one preferred embodiment, the first mechanism has a drive. The actuator is driven via the drive. 
     The drive is advantageously a worm drive or a worm gear. 
     Furthermore, the first mechanism advantageously has a first hollow gear, a first planetary gear set and a first sun gear. In order to drive the actuator, the worm drive engages in the region on the circumference of the first hollow gear which is correspondingly configured for an intervention by the worm drive. 
     Planetary gear mechanisms have the advantage of having a characteristic compact design. The advantage of planetary gear mechanisms over other types of transmission is therefore, on the one hand, a compact size with a comparable transmission ratio, and, on the other hand, the possibility of coaxial changes of direction. 
     The first mechanism preferably also has the ramp mechanism or alternatively some other mechanism which ensures longitudinal displacement of the inner shaft. In this context, the ramp mechanism has a ramp planetary gear set, a first ramp, which is permanently connected to the inner shaft, and a second ramp, which is permanently arranged in a ramp housing. At least one ramp body is arranged between the first ramp and the second ramp, which are arranged following one another in the axial direction of the output unit. The ramp body can be a ball or a roller. 
     The first mechanism preferably also has a compression spring which is adapted and arranged so as to compress the first ramp and the second ramp. The compression spring applies here a continuous force to the first ramp and the second ramp, and therefore provides the first ramp and the second ramp with a tension which presses the first ramp and the second ramp against one another, and therefore ensures pre-loading into the coupling state. 
     The advantage of a ramp mechanism with a ramp which can be displaced in the axial direction of the output unit is that from a selective configuration of the ramps, selective and therefore previously accurately determinable axial displacement of the displaceable inner shaft and therefore of the ramp, is also made possible. Controlled de-meshing and meshing of the bevel gear are therefore guaranteed. If the first ramp and the second ramp are clamped against one another in an undeviating fashion by means of a spring, in particular by means of a compression spring, a satisfactory and previously determined movement of the ramp body is therefore brought about. 
     The first mechanism advantageously has a further spring, in particular a bow spring, which is arranged between the first sun gear and the ramp mechanism. 
     The advantage of a bow spring between the first sun gear and the ramp mechanism is that the shifting energy of the freewheel shifting is buffered in the bow spring. This is advantageous in particular when the tooth heads of the bevel gear prevent immediate meshing in the differential after shifting. As a result of the use of the bow spring, the bevel gear jumps again into engagement as soon as the vehicle, which has the crank-CVT transmission, approaches slowly, and the first ramp locks the position. The energy which is required for meshing is therefore buffered by the spring. 
     The second mechanism advantageously has a second hollow gear, a second planetary gear set and a second sun gear. 
     The second mechanism also advantageously has a third hollow gear, a third planetary gear set and a third sun gear. 
     It is preferred here if the first sun gear and the third sun gear are mounted rotatably in the output unit, and the second sun gear is permanently connected to the ramp housing. The second sun gear is permanently arranged on the circumference of the ramp housing. 
     In addition to the advantage of having a compact design, the coaxial change of direction, which is achieved by means of three or more usually coaxially arranged shafts in the planetary gear mechanism, is particularly advantageous. Forces which are applied radially far on the outside to the output unit, in particular to the first hollow gear, can be passed on radially into the interior of the output unit by means of a planetary gear mechanism and/or a plurality of planetary gear mechanisms. 
     The first planetary gear set of the first mechanism and the second planetary gear set and third planetary gear set of the second mechanism advantageously have a common planetary gear carrier. The planetary gear carrier corresponds to a web on which the first, second and third planetary gear set are arranged. 
     As a result of the common planetary gear carrier, the shifting process is advantageously linked to the decoupling process. As a result, the shifting of the freewheel device does not take place chronologically until the decoupling of the bevel gear from the differential is terminated. This means that the shifting of the freewheel device does not take place until the bevel gear is decoupled from the differential and the output unit is therefore load-free. This ensures that the freewheel device of the crank-CVT transmission is shifted only when the crank-CVT transmission is load-free. 
     The second hollow gear of the second mechanism advantageously has, on the surface which is assigned to the first hollow gear, at least one arcuate groove in which a pin, which is permanently connected to the first hollow gear, is arranged. In this context, the at least one groove runs in the radial direction of extent or extension of the second hollow gear. The pin permits a connection of the first gearwheel to the second gearwheel. 
     The second gearwheel advantageously has, on the surface which is assigned to the first hollow gear, three arcuate grooves in each of which a pin, which is permanently connected to the first hollow gear, is arranged. In this context, the three grooves run in the radial direction of extent or of extension of the second hollow gear. The pins permit a connection of the first hollow gear to the second hollow gear. 
     The connection of the first hollow gear and of the second hollow gear by means of pins which run in grooves is particularly advantageous since in this way the rotation of the first hollow gear relative to the second hollow gear can be controlled in a selective fashion. That is to say the rotation of the second hollow gear is dependent on the position of the first hollow gear. By means of the grooves in the second hollow gear in which the pins which are permanently connected to the first hollow gear run, it is possible to determine precisely when the shifting of the freewheel unit can take place or is to take place, specifically as soon as the output unit of the crank-CVT transmission is load-free. 
     The second hollow gear of the second mechanism and the third hollow gear of the second mechanism are preferably connected to one another by means of at least one indent connection. 
     The indent connection has the advantage of preventing rotation of the second hollow gear with respect to the first hollow gear during the shifting process of the freewheels and of therefore permitting smooth shifting. As a result, the second hollow gear and the third hollow gear are not permanently connected to one another but rather coupled to one another only during the shifting process of the freewheel device. 
     The shifting unit preferably corresponds to a spindle or to a spindle unit which is composed of a plurality of spindle rods which can in turn be displaced in the axial direction of the output shaft. The freewheel device is shifted by means of the axial displacement. For this purpose, the spindle unit has chamfers or notches in the radial direction on its circumference. 
     A large number of freewheels can advantageously be shifted by means of a spindle unit which is configured so as to be displaceable in the axial direction of the output shaft. 
     The freewheel device is preferably embodied as a shiftable freewheel which optionally blocks a relative rotation in a first or second direction of relative rotation between the freewheel device and the output shaft, and enables relative rotation between the freewheel device and the output shaft in the other of the first or second directions of relative rotation. 
     Shiftable freewheels have the advantage of having a compact and therefore stable design, and of therefore being particularly resistant to wear and able to cope with loading in an enduring fashion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described below on the basis of the appended figures, in which: 
         FIG. 1  shows a cross-sectional view in the axial direction of an output unit of a crank-CVT transmission according to the present invention with an actuator and a meshed bevel gear between a Cardan shaft of the transmission and a differential, 
         FIG. 2  shows a cross-sectional view of the drive unit of a crank-CVT transmission with an actuator and a de-meshed bevel gear, 
         FIG. 3  shows a cross-sectional view of the actuator, 
         FIG. 4  shows a perspective view of the Cardan shaft with a compression spring, a ramp mechanism and a bevel gear, 
         FIG. 5  shows a perspective view of the Cardan shaft with the compression spring, a spindle and a ramp housing, 
         FIG. 6  shows a perspective view of the output shaft with the spindle and the ramp housing, 
         FIG. 7  shows a perspective view of the output shaft with the spindle, 
         FIG. 8  shows a perspective view of the output shaft with a first hollow gear, a worm drive and a second hollow gear, 
         FIG. 9  shows a perspective view of the output shaft with the first hollow gear, the worm drive, the second hollow gear and a third hollow gear, 
         FIG. 10  shows a perspective view of the second hollow gear, 
         FIG. 11  shows a perspective view of the first hollow gear, 
         FIG. 12  shows a plan view of the second hollow gear and the ramp mechanism in a first shifting phase, 
         FIG. 13  shows a plan view of the second hollow gear and the ramp mechanism in a second shifting phase, 
         FIG. 14  shows a plan view of the second hollow gear and the ramp mechanism in a third shifting phase, 
         FIG. 15  shows a plan view of the second hollow gear and the ramp mechanism in a fourth shifting phase, 
         FIG. 16  shows a plan view of the second hollow gear and the ramp mechanism in a fifth shifting phase, 
         FIG. 17  shows a plan view of the second hollow gear and the ramp mechanism in a sixth shifting phase, 
         FIG. 18  shows a plan view of the second hollow gear and the ramp mechanism in a seventh shifting phase, and 
         FIG. 19  shows a plan view of the second hollow gear and the ramp mechanism in an eighth shifting phase. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The figures show an embodiment of a crank-CVT transmission according to the invention. 
       FIGS. 1 and 2  show, in particular, an output unit  1  of a crank-CVT transmission. A freewheel device  10  is provided in the form of a plurality of freewheels which are arranged successively in the axial direction and have the purpose of connecting to the drive side of the transmission (not illustrated). The freewheels which for this purpose have, for example, articulation points for connecting-rod-like connecting elements connecting to the eccentric units of the drive side. The freewheels are provided on an output shaft  500  of the transmission. Provided in the axial direction in the output shaft  500  are bores in each of which a spindle unit  30  is respectively accommodated in an axially displaceable fashion. In this context, the spindle unit  30  includes a plurality of spindle rods  300  and serves as a shifting device. The output unit  1  has, in the axial direction, a first end  40  which corresponds to a connecting point for connecting to a differential  2 , and a second end  50  which provides, for example, a bearing of the output shaft  500  on the housing. The freewheel device  10  is arranged at the second end  50 . An actuator  20 , which will be described later in detail, is provided at the first end  40 . 
     Furthermore, a central through-bore, in which an inner shaft or Cardan shaft  400  is arranged, is arranged in the output shaft  500 . The Cardan shaft  400  extends from the first end  40  as far as the second end  50  of the transmission. A bevel gear  180  is arranged on the Cardan shaft  400 , at the first end  40 . In the axial direction of the Cardan shaft  400 , a ramp mechanism  160  is arranged following the bevel gear  180 , in the direction of the second end  50 . In addition, a compression spring  164  is provided which is arranged in a helical shape around the Cardan shaft  400 , and which pre-loads the Cardan shaft  400  with respect to the output shaft  500  in the direction of the differential  2 . The compression spring  164  is arranged following the ramp mechanism  160  in the direction of the second end  50 , in the axial direction of the Cardan shaft  400 . 
     In the sectional views shown in  FIGS. 1 and 2  of the output unit  1 ,  FIG. 1  shows a state of the crank-CVT transmission in which the output unit  1  is coupled to the differential  2 , and the output unit  1  is connected to the differential  2  via the bevel gear  180 .  FIG. 2  shows a state of the crank-CVT transmission in which the output unit  1  is not coupled to the differential  2 , and the bevel gear  180  of the output unit  1  is not connected to the differential  2 . For the coupled state, the bevel gear  180  is positioned at the outermost first end  40  of the output unit  1 . For the uncoupled state, the bevel gear  180  is moved back in the direction of the second end  50  of the output unit  1 . 
       FIG. 3  shows an enlarged view of the actuator  20  from  FIG. 2 . The design of the actuator  20  is explained below on the basis of  FIGS. 3 to 11 . 
     The actuator  20  is arranged at the first end  40 . The actuator  20  has a first mechanism  100  (on the right in  FIG. 3 ) for the decoupling of the output unit  1  from the differential  2 , and a second mechanism  200  (on the left in  FIG. 3 ) for activating the spindle unit  30 . In this context, the first mechanism  100  is arranged close to the end  40  of the output unit  1 , and the second mechanism  200  is arranged behind the first mechanism  100  in the axial direction of the output unit  1 , in the direction of the second end  50 . The spindle unit  30  adjoins the second mechanism  200  in the axial direction and extends as far as the second end  50  of the output unit  1 . 
     The first mechanism  100  of the actuator  20  has a first hollow gear  110 , a first planetary gear set  120 , which meshes with the first hollow gear  110 , and a first sun gear  130  which is mounted in the output unit  1  and meshes with the first planetary gear set. Furthermore, the first mechanism  100  has a ramp mechanism  160 . The ramp mechanism  160  includes a ramp planetary gear set  140  which includes three ramp planetary gearwheels, a first ramp  161 , a second ramp  162  and three spherical ramp bodies  163  (see  FIGS. 12 to 19 ) which are arranged in a guide groove with a depth between the first ramp  161  and the second ramp  162  which can be varied along the circumference. The bevel gear  180  is arranged next to the ramp mechanism  160 , in the axial direction of the output unit  1  (in the direction of the first end  40 ). The ramp mechanism  160  also has a ramp housing  150 . In addition, the first mechanism  100  has a bow spring  170 , serving here to store the shifting energy, between the first sun gear  130  and the ramp mechanism  160 . 
     In a cutout in a transmission housing  600 , a worm drive  105  is arranged which engages on an outer circumference of the first hollow gear  110  that is positioned underneath the cutout in the transmission housing  600 . 
     The second mechanism  200  is arranged following the first mechanism  100  in the axial direction of the output unit  1  (in the direction of the second end  50 ). The second mechanism  200  includes a second hollow gear  210 , a second planetary gear set  220  and a second sun gear  230 . The second sun gear  230  is permanently connected to the ramp housing  150 . The second mechanism  200  also has a third hollow gear  240 , a third planetary gear set  250  and a third sun gear  260 , which is mounted in the output unit  1 . Here, the third hollow gear  240 , the third planetary gear set  250  and the third sun gear  260  are arranged, behind the respective second hollow gear  210 , the second planetary gear set  220  and the second sun gear  230  in the axial direction of the output unit  1  (in the direction of the second end  50 ). The third sun gear  260  meshes with the spindle rods  300  of the spindle unit  30 . A ramp housing  150  is arranged in the region of the actuator  20 , between the Cardan shaft  400  and the output shaft  500 . 
     The first hollow gear  110  is connected to the second hollow gear  210  by means of three pins  212  which are permanently attached to the end face of the first hollow gear  110  and run in the grooves  211  in the end face of the second hollow gear  220  (see  FIGS. 10 and 11 ). The second hollow gear  210  is connected to the third hollow gear  240 , which is fixedly arranged in the transmission housing  600 , by means of an indent connection  241  which contains essentially a helical spring and a ball. 
     The first planetary gear set  120 , the second planetary gear set  220  and the third planetary gear set  250  have a common planetary gear carrier  270  and each include three planetary gears. 
     Individual parts of the crank-CVT transmission are shown in a perspective view in  FIGS. 4 to 11 . 
       FIGS. 4 and 5  show perspective views of the Cardan shaft  400  on which the compression spring  164  is arranged in a helical shape. 
     In this context,  FIG. 4  shows the bevel gear  180  which is arranged at the first end  40  of the output unit  1  on the Cardan shaft  400 . The ramp mechanism  160  is arranged behind the bevel gear  180  in an axial direction of the output unit  1  (in the direction of the second end  40 ) on the Cardan shaft  400 . In this context, the first ramp  161  has a sun gear section which serves to mesh with the ramp planetary gear set  140  of the first mechanism  100 . The first ramp  161  is mounted so as to be displaceable in the axial direction of the output unit  1 . The second ramp  162  is permanently connected to the output unit  1 . 
       FIG. 5  shows the ramp housing  150  which comprises the bevel gear  180  and the ramp mechanism  160 . The ramp planetary gear set  140  penetrates, with the three ramp planetary gearwheels, the ramp housing  150  at three cutouts provided for this purpose in the ramp housing  150 . 
       FIGS. 6 to 9  show the output shaft  500 , the spindle unit  30  and the ramp housing  150  with the cutouts for the three ramp planetary gearwheels of the ramp planetary gear set  140 . The spindle unit  30  has six separate axially displaceable spindle rods  300  which are mounted in the output shaft  500  ( FIG. 7 ). 
       FIG. 8  shows the first hollow gear  110  as well as the worm drive  105 , which acts on an outer circumference of the hollow gear  110 . The first hollow gear  110  is adapted in such a way that the worm drive  105  can act on the outer circumference of the first hollow gear  110 . This means that the first hollow gear  110  has, on its outer circumference, a correspondingly formed groove profile for the engagement of the worm drive  105 . 
       FIG. 9  shows the first hollow gear  110 , the second hollow gear  210  and the third hollow gear  240  which are arranged one behind the other in the axial direction of the output unit  1  radially around the output shaft. The first hollow gear  110  is arranged near to the first end  40  of the output unit  1 , and the second hollow gear  210  and the third hollow gear  240  are arranged behind the first hollow gear  110  in the direction of the second end  50 . 
       FIG. 10  shows a perspective view of the second hollow gear  210 . On the side facing the first end  40  of the drive unit  1 , three arcuate grooves  211  are arranged near to the circumference of the second hollow gear  210 . In each of the three grooves  211 , a pin  212  is arranged in a displaceable fashion. 
       FIG. 11  shows the first hollow gear  110  and three pins  212  which are arranged uniformly on the side of the first hollow gear  100  facing the second end  50 , near to the circumference of the first hollow gear  110 . The pins  212 , which are displaceable in the grooves  211  ( FIG. 10 ), are permanently connected to the first hollow gear  110 . 
     A plan view of the second ramp  162  is shown in  FIGS. 12 to 19 . 
     The second ramp  162  has, on a side or face which faces or is assigned to the first end  40  of the output unit  1 , three arcuate ramp regions  165  which are distributed uniformly in the circumferential direction. Each of the three arcuate ramp regions  165  contains two first ramp sections  166 , two second ramp sections  167  and two third ramp sections  168 . The two third ramp sections  168  bear one next to the other. On the outside, the two second ramp sections  167  adjoin the two third ramp sections  168 , and the two first ramp sections  166  adjoin the two second ramp sections  167 , with the result that, in a plan view onto the ramp  162 , the two first ramp sections  166 , the two second ramp sections  167  and the two third ramp sections  168  are each symmetrical with respect to an axis of symmetry which separates the first ramp section  166  from one another. 
     The first ramp sections  166  and the third ramp sections  168  are without a gradient along the ramp  162  and therefore have ramp faces which are each perpendicular to the axial direction of the output unit  1 . However, the first ramp faces  166  and the third ramp faces  168  are located in different planes from one another, perpendicularly with respect to the axial direction. The second ramp sections  167  connect the first ramp sections  166  to the third ramp sections  168  and have ramp faces which drop away. The first ramp sections  166  are therefore proud to the greatest degree, or recessed to the least degree, with respect to the ramp  162  in the axial direction of the output unit  1  (in the direction of the first end  40 ), while the third ramp sections  168  are countersunk to the greatest extent into the ramp  162  in the axial direction of the output unit  1  (in the direction of the second end  50 ). 
     The method of functioning of the shifting mechanism and of the actuator will be described below: 
       FIGS. 12 to 19  show, by means of plan views onto the second hollow gear  210  and onto the second ramp  162 , various shifting phases of the actuator  20 . The shifting phases are dependent on the position of the three pins  212  in the three grooves  211  of the second hollow gear  210  and on the position of the three conical ramp bodies  163  in the second ramp  162 . 
     In  FIG. 12 , the three pins  212  are located in the three grooves  211  between the first groove end point  213  and the second groove end point  214  of the grooves  211 . The three conical ramp bodies  163  are each positioned on the first ramp sections  166 . This means that  FIG. 12  shows the first shifting phase of the actuator  20 . In the first shifting phase, the output unit  1  of the crank-CVT transmission is connected to the differential  2 , that is to say the bevel gear  180  is coupled to the differential  2 , and the freewheel device  10  of the output unit  1  permits a rotational movement of the output unit  1  in a first direction of rotation. The conical ramp bodies  163  are arranged on the first ramp sections  166  here, and the pins  212  are located here in the grooves  211  at a position between the first groove end points  213  and the second groove end points  214 . 
     In order to drive the shifting mechanism  20  of the freewheels, the worm drive  105  begins (not illustrated) to drive the first hollow gear  110  (not illustrated). In this context, the second hollow gear  210  initially does not rotate. The pins  212  which are permanently connected to the first hollow gear  110  run in the grooves  211  of the second hollow gear  210  in a first direction of rotation. The conical ramp bodies  163 , which are located in the first ramp sections  166  in  FIG. 12 , move as a result of the rotations of the first ramp  161  (not illustrated) in the first direction of rotation along the ramp regions  165 , also in the first direction of rotation, which is shown in  FIG. 13 . 
     In  FIG. 13 , the three pins  212  are each located at a first groove end point  213  of the respective groove  211 . The three conical ramp bodies  163  are each positioned on the second ramp sections  167  which correspond to a movement of the conical ramp bodies  163  in a first direction of rotation. This means that  FIG. 13  shows the second shifting phase. In the second shifting phase, the output unit  1  of the crank-CVT transmission is no longer connected to the differential  2 , that is to say the bevel gear  180  is decoupled from the differential  2 . For this purpose, the spherical ramp bodies  163  are located in the second ramp section  167  which drops away from the first ramp section  166  in the direction of the third ramp section, and they therefore press the ramps  161 ,  162  apart, which leads to a relative displacement of the Cardan shaft  400  with respect to the output shaft  500 . The pins  212  abut against the first groove end points  213  with the second hollow gear  210 . 
     Since the first hollow gear  110  still rotates in a first direction of rotation, the second hollow gear  210  is entrained in the first direction of rotation by the first hollow gear  110  starting from the moment at which the pins  212  abut against the first groove end points  213 . The spherical ramp bodies  163  likewise move further in the first direction of rotation, which is shown in  FIG. 14 . 
     In  FIG. 14 , the three pins  212  are each located at the first groove end points  213  of the respective grooves  211 . The three spherical ramp bodies  163  are each positioned on the third ramp sections  168 , which correspond to a movement of the spherical ramp bodies  163  in a first direction of rotation. This means that  FIG. 14  shows the third shifting phase. In the third shifting phase, the output unit  1  of the crank-CVT transmission is likewise not connected to the differential  2 , that is to say the bevel gear  180  is still decoupled from the differential  2 . Pins  212  are located at the first groove end points  213 , and the spherical ramp bodies  163  are arranged in the third ramp section  168 . 
     The second hollow gear  210  therefore rotates, via the second planetary gear set  220  and the planetary gear carrier  270 , the third planetary gear set and the third sun gear  260  which drives the spindle unit  30 , thereby shifting the freewheel device  10  from the first direction of rotation to the second direction of rotation. The shifting of the freewheel device  10  from the first direction of rotation into a second direction of rotation therefore takes place in the third shifting phase. 
     In order to avoid rotation of the second hollow gear  210  with respect to the third hollow gear  250  during the shifting of the freewheel unit  10 , the second hollow gear  210  is held in position relative to the third hollow gear  250  by means of the indent connection  241  during the shifting process. Since the shifting process is past, the indent connection  241  and the second hollow gear  210  can rotate again with respect to the third hollow gear  250 , which is shown in  FIG. 15 . 
     The shifting of the freewheel device  10  from a first direction of rotation into a second direction of rotation causes all the rotating components of the output unit  1  to move in a second direction of rotation. 
     In  FIG. 15 , the three pins  212  are located between the respective first groove end points  213  and the respective second groove end points  214  of the grooves  211 . The three spherical ramp bodies  163  are each positioned on the second ramp sections  167  which correspond to a movement of the spherical ramp bodies  163  in a second direction of rotation. This means that  FIG. 15  shows the fourth shifting phase. The output unit  1  of the crank-CVT transmission is not connected to the differential  2  in the fourth shifting phase either, that is to say the bevel gear  180  is decoupled from the differential  2 . The three pins  212  are arranged in the grooves  211 , in each at a position between the first groove end points  213  and the second groove end points  214 . The spherical ramp bodies  163  are located on the second ramp sections  167 . 
     The pins  212  move in the grooves  211  from the first groove end points  213  in the direction of the second groove end points  14  in the second direction of rotation. The second hollow gear  210  therefore does not rotate. The spherical ramp bodies  163  move in the second direction of rotation, which is shown in  FIG. 16 . 
     In  FIG. 17 , the three pins  212  are each positioned at the respective second groove end points  214  of the grooves  211 . The three spherical ramp bodies  163  are each positioned on the first ramp sections  166 . This means that  FIG. 17  shows the fifth shifting phase. In the fifth shifting phase, the output unit  1  of the crank-CVT transmission is again connected to the differential  2 , that is to say the bevel gear  180  is again coupled to the differential  2  in order to transmit the second direction of rotation of the output unit  1  to the differential  2 . 
     In this context, the spherical ramp bodies  163  move on in the second direction of rotation and in the fifth shifting phase they are again located on the first ramp sections  166 . The pins  212  still run in the second direction of rotation in the grooves  211  between the first groove end points  213  and the second groove end points, and the second hollow gear  210  therefore does not move. 
     As soon as renewed shifting of the freewheel device  10  is to be carried out for a reversal of the direction of rotation, the decoupling of the output unit  1  from the differential  2  takes place again in order to permit load-free shifting of the freewheel device  10 . This can be seen in  FIG. 17 . 
     In  FIG. 17 , the three pins  212  are each located at the second groove end points  214  of the grooves  211 . The three spherical ramp bodies  163  are each positioned on the second ramp sections  167  which correspond to a movement of the spherical ramp bodies  163  in a second direction of rotation. This means that  FIG. 17  shows the sixth shifting phase. In the sixth shifting phase, the output unit  1  of the crank-CVT transmission is no longer connected to the differential  2 , that is to say the bevel gear  180  is decoupled from the differential and the output unit is load-free. 
     Since the output unit  1  still rotates in the second direction of rotation, the spherical ramp bodies  163  firstly also move in the second direction of rotation. The pins  212  move in the grooves  211  in a second direction of rotation and therefore abut against the second groove end points  214 . Starting from this time, the second hollow gear  210  is again entrained by the first hollow gear  110  and moves in the second direction of rotation, which is shown in  FIG. 18 . 
     In  FIG. 18 , the three pins  212  are located between the respective groove end points  213  and the respective second groove end points  214  of the grooves  211 . The three spherical ramp bodies  163  are each positioned on the third ramp sections  168 , which correspond to a movement of the spherical ramp bodies  163  in a second direction of rotation. This means that  FIG. 18  shows the seventh shifting phase. In the seventh shifting phase, the output unit of the crank-CVT transmission  1  is, furthermore, not connected to the differential  2 , that is to say the bevel gear  180  continues to be decoupled from the differential. The pins  212  continue to be located at the groove end points  214 , and the spherical ramp bodies  163  on the third ramp sections  168 . 
     As a result of the connection of the first hollow gear  110  (not illustrated) to the second hollow gear  210  via the pins  212  which are located at the groove end points  214 , the second hollow gear  210  is entrained further in the second direction of rotation. The second hollow gear therefore rotates, via the second planetary gear set  220  and the planetary gear carrier  270 , the third planetary gear set and the third sun gear  260  which drives the spindle  300  in order to shift the freewheel device  10  from the second direction of rotation to the first direction of rotation, which is shown in  FIG. 19 . 
     The second hollow gear  210  therefore rotates via the second planetary gear set  220  and the planetary gear carrier  270  the third planetary gear set and the third sun gear  260  which drives the spindle unit  30  and therefore shifts the freewheel device  10  from the second direction of rotation to the first direction of rotation. As a result, the freewheel device  10  shifts from the second direction of rotation into a first direction of rotation, that in the seventh shifting phase. 
     In  FIG. 19 , the three pins  212  are located between the respective first groove end points  213  and the respective second groove end points  214  of the grooves  211 . The three spherical ramp bodies  163  are each positioned on the second ramp sections  167  which correspond to a movement of the spherical ramp bodies  163  in a first direction of rotation. This means that  FIG. 19  shows the eighth shifting phase. In the eighth shifting phase, the output unit of the crank-CVT transmission  1  is furthermore not connected to the differential  2 , that is to say the bevel gear  180  is still decoupled from the differential. 
     The pins  212  move again in a first direction of rotation and are located in the grooves  211  at positions between the first groove end positions  213  and the second groove end positions  214 . The spherical ramp bodies  163  likewise move in the first direction of rotation and are arranged on the second ramp sections  167 . 
     The ninth shifting phase corresponds to the first shifting phase which is shown in  FIG. 12 . In the first shifting phase, the output unit  1  of the crank-CVT transmission is again connected to the differential  2 , that is to say the bevel gear  180  is coupled to the differential  2 , and the freewheel device  10  of the output unit  1  permits rotation of the rotating components of the output unit  1  in the first direction of rotation. In this context, the spherical ramp bodies  163  are arranged on the first ramp sections  166 , and the pins  212  are located in the grooves  211  at a position between the first groove end points  213  and the second groove end points  214 . 
     During operation of the crank-CVT transmission  1 , the first mechanism  100  is firstly activated in order to shift the freewheel device  10 . For this purpose, the worm drive  105  drives the first hollow gear  110 . The first hollow gear  110  in turn drives the first planetary gear set  120 , which meshes with the first sun gear  130  and drives the first sun gear  130 . The first sun gear  130  meshes with the ramp planetary gear set  140 , which engages in the sun gear section of the first ramp  161 , and therefore drives the first ramp  161  of the ramp mechanism  160 . Through the rotation of the first ramp  161 , the three spherical ramp bodies  163  migrate along the ramp region  165  between the first ramp  161  and the second ramp  162 , and they move the first ramp  161  in the axial direction of the output unit, in the direction of the first end  40  of the output unit  1  counter to the pre-loading of the spring  164 . 
     The second ramp  162  cannot be displaced in the axial direction of the output unit. Depending on the direction of rotation of the first ramp  161 , the spherical ramp bodies  163  move in a first direction of rotation or a second direction of rotation and accordingly into ramp regions  165  which correspond to the first direction of rotation or the second direction of rotation. 
     If the spherical ramp bodies  163  are located on the respective first ramp sections  166  of the ramp regions  165 , the first ramp  161  is displaced in the direction of the first end  40  over a maximum possible distance in the axial direction of the drive unit  1 . In this state, the bevel gear  180  of the output unit  1  is connected or coupled to the differential  2 , and torque is therefore transmitted from the output unit  1  to the differential  2 . 
     If the spherical ramp bodies  163  are located on the third ramp sections  168  of the ramp regions  165 , the first ramp  161  is displaced in the direction of the second end  50  over a maximum possible distance in the axial direction of the drive unit  1 . In this state, the bevel gear  180  of the output unit  1  is not connected or coupled to the differential  2 . That is to say the bevel gear  180  is decoupled from the differential  2 , and torque is not transmitted from the output unit  1  to the differential  2 . 
     While the first mechanism  100  serves to decouple or couple the bevel gear  180 , the second mechanism  200  is not activated. This means that the pins  212  which connect the first hollow gear  110  of the first mechanism  100  and the second hollow gear  210  of the second mechanism  200  to one another run in the grooves  211  during the decoupling process of the bevel gear, therefore preventing the second hollow gear  210  from rotating with the first hollow gear  110  during the decoupling process of the bevel gear  180 . 
     When the decoupling process is terminated, that is to say the bevel gear  180  is decoupled from the differential  2  and the output unit  1  is therefore load-free, the three pins  212  therefore respectively impact against the first groove end points  213  of the grooves  211 . As soon as the three pins  212  have reached the first groove end points  213  of the grooves  211 , the second hollow gear  210  is entrained by the first hollow gear  110  and therefore driven. Since a connection is generated between the first hollow gear  110  and the second hollow gear  210  by means of the pins  212 , the first hollow gear  110  and the second hollow gear  210  rotate together in a first common direction of rotation at the same speed. 
     The second hollow gear  210  drives the second planetary gear set  220  which meshes with the second sun gear  230 . The sun gear  230  is permanently connected to the output unit  1 . The rotation of the second planetary gear set  220  therefore drives the planetary gear carrier  270 . 
     The planetary gear carrier  270  in turn drives the third planetary gear set  250  which meshes with the third hollow gear  240 , which is permanently arranged in the transmission housing  600 , and with the third sun gear  260 , which is connected to the spindle unit  30 . The third sun gear  260  drives the spindle unit  30 , which is arranged in the output shaft  500 . 
     The spindle unit  30  can be displaced in the axial direction. As a result of the axial displacement of the spindle unit  30 , the shifting of the freewheel device  10  takes place, for example by means of coil spring mechanisms in conjunction with spherical sections of the spindle unit  30 . 
     So that the bevel gear  180  couples satisfactorily into the differential  2 , a how spring  170  is arranged between the first sun gear  130  and the ramp mechanism  160 , which bow spring  170  stores energy when the freewheel device  10  shifts, and said sun gear  130  and the ramp mechanism  160  assists the coupling of the bevel gear  180  in the differential  2  if the tooth heads of the bevel gear prevent immediate coupling. 
     Smooth functioning of the ramp mechanism  160  is ensured by a compression spring  164  which is arranged in a helical shape around the Cardan shaft  400  and which always compresses the first ramp  161  and the second ramp  162 , and is therefore under tension. 
     LIST OF REFERENCE NUMERALS 
     
         
           1  Output Unit 
           2  Differential 
           10  Freewheel Device 
           20  Actuator 
           30  Shifting Unit, Spindle Unit 
           100  First Mechanism 
           105  Drive, Worm Drive 
           110  First Hollow Gear 
           120  First Planetary Gear Set 
           130  First Sun Gear 
           140  Ramp Planetary Gear Set 
           160  Ramp Mechanism 
           150  Ramp Housing 
           161  First Ramp 
           162  Second Ramp 
           163  Ramp Body 
           164  Compression Spring 
           165  Ramp Region 
           166  First Ramp Section 
           167  Second Ramp Section 
           168  Third Ramp Section 
           170  Bow Spring 
           180  Connecting Means, Bevel Gear 
           200  Second Mechanism 
           210  Second Hollow Gear 
           211  Groove 
           212  Pin 
           213  First Groove End Point 
           214  Second Groove End Point 
           220  Second Planetary Gear Set 
           230  Second Sun Gear 
           240  Third Hollow Gear 
           241  Indent Connection 
           250  Third Planetary Gear Set 
           260  Third Sun Gear 
           270  Planetary Gear Carrier 
           300  Spindle Rod 
           400  Cardan Shaft 
           500  Output Shaft 
           600  Transmission Housing