Abstract:
A lever system for actuating a clutch in the power train of a motor vehicle or of a disc brake, including: a lever ( 7 ) with a first side ( 7.1 ) rotatably supported on a pivot ( 8 ) and with a side ( 7.2 ) in functional connection with a pressing means ( 6 ). The lever ( 7 ) rests on a movable fulcrum ( 12 ) provided by a moveable support unit ( 10 ) that is displaceable in radial direction relative to the rotation axis of the clutch or the disc brake and which is displaceable using a motor-driven ( 15 ) spindle ( 14 . The moveable support unit ( 10 ) rests on a raceway ( 11 ) and includes two roller sets ( 20.1, 20.2 ) each with rollers ( 21, 22, 22.1, 22.2 ). Each of the roller set ( 20.1, 20.2 ) includes at least three rollers ( 21, 22, 22.1, 22.2 ) and at least two of the rollers ( 22.1, 22.2 ) include approximately equal first diameters.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is filed under 35 U.S.C. §120 and §365(c) as a continuation of International Patent Application PCT/DE2007/000733, filed Apr. 25, 2007, which said application claims priority from German Patent Application No. 10 2006 023 806.0, filed May 20, 2006, which applications are incorporated herein by reference in their entirety. 
   FIELD OF THE INVENTION 
   The present invention relates to a lever system for actuating a clutch, for example, a clutch in the power train of a motor vehicle or a brake, in particular a disc brake including a lever that is rotatably supported on one side about a pivot and the other side is in functional connection with a pressing means. The lever rests on a fulcrum on a runner unit that is displaceable in the radial direction by means of a motor-driven spindle and the runner unit rests on a raceway fixed to the housing and includes at least one roller set with runners. 
   BACKGROUND OF THE INVENTION 
   A generic clutch release system is known from the DE 10 2004 009832 document.  FIG. 2  and  FIG. 3 , explained further below, show an exemplary embodiment of a lever system according to prior art. 
   In solutions based on prior art, the introduction of torque to the axles or to the mounting points of roller set axles in a hub is disadvantageous. 
   BRIEF SUMMARY OF THE INVENTION 
   The object of the present invention is to provide a lever system in which only small torque is introduced to the fixing point of roller set axles in a hub. 
   This object is met by means of a lever system for actuating a clutch, for example, a clutch in the power train of a motor vehicle or of a brake, in particular a disc brake comprising a lever, one side of which is rotatably supported about a pivot and the other side of which is in functional connection with a pressing means. The lever rests with one fulcrum on a runner unit displaceable in the radial direction and displaceable by means of a motor-driven spindle. The runner unit rests on a raceway fixed to the housing and at least includes a roller set with runners. The roller set comprises at least three runners, of which at least two runners feature a first diameter substantially equal and at least one runner that features a second diameter that differs from the first diameter. The terms first and second diameter are only chosen to distinguish between the two different diameters; which one of the two diameters is greater or smaller is not clarified by the terms first diameter and second diameter. Preferably, runners are disposed with approximately equal diameters on both sides of the runner with deviant diameter. Thus, runners with the first diameter rest on the lever and runners with the second diameter rest on the raceway. Preferably, runners with the first diameter rest on the lever and runners with the second diameter rest on the raceway. In that case, the first diameter can be the larger diameter and the second diameter the smaller diameter; the assignment can also be reversed. The roller set preferably comprises three runners. The two runners with approximately equal first diameter have a smaller diameter than the third runner. The preceding runner arrangement can also be reversed in principle, thus, it can be provided also that the roller set comprises three runners and the two runners with approximately equal first diameters have a larger diameter than the third runner. In one embodiment, the two runners with approximately equal diameters rest on the raceway and runners with the larger diameter rest on the lever. Preferably, the runners with the larger diameter engage with a section of the raceway. Owing to the engagement of the runner in the section, lateral guidance of the runner and thus of the roller set or of the entire runner unit is effectuated. In one embodiment, the two runners with approximately equal diameters comprise discs that project radially beyond runners and engage with the section of the raceway. The discs likewise bring about lateral guidance, in this case, a lateral guidance of the two runners with the smaller diameter. In one embodiment of the lever system according to the invention, the roller sets respectively rest loosely on an assigned idler roller that is disposed on an idler roller axle connected with the hub. The idler rollers bear the forces acting tangentially to the raceway; and the roller sets bear the forces acting in the normal direction to the raceway or in the normal direction to the lever. Advantageously, the normal forces do not generate torque on an axle of the roller sets. In one embodiment of the lever system according to the invention, the idler roller axle assigned to a roller set is connected with the respective axle of the roller set such that radial displacement of either towards one another is not possible. This connection can be executed, for instance, in the form of a cage that connects the respective idler roller axle with the respective axle. This arrangement corresponds functionally with a rod that connects the two axles with one another, where the two axles are mounted in a rotatable manner relative to the rod. 
   The problem mentioned above is solved by means of a runner unit for a lever system for actuating a clutch, for example, a clutch in the power train of a motor vehicle or of a brake, in particular a disc brake. The lever system comprises a lever that on one side is mounted rotatably about a pivot. The lever rests with one fulcrum on a runner unit displaceable in radial direction and displaceable by means of a motor-driven spindle. The runner unit rests on a raceway fixed to the housing and includes at least one roller set with runners. The roller set includes at least three runners, of which at least two runners feature approximately equal first diameters and at least one runner features a second diameter that is deviant from the first diameter. The problem mentioned above is also solved by means of a clutch release system for a clutch in the power train of a motor vehicle with a lever system according to the invention as well as a motor vehicle with a clutch release system for a clutch comprising a lever system according to the invention. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     Exemplary embodiments of the invention are explained in the following passage, based on the attached drawings. The figures are as follows: 
       FIG. 1  is a schematic depiction of a lever system according to the invention; 
       FIG. 2  is a side-view of a prior art runner unit; 
       FIG. 3  is a cross-sectional view along Section Z-Z in  FIG. 2 ; 
       FIG. 4  is side view of a first exemplary embodiment of a runner unit according to the invention; 
       FIG. 5  is a cross-sectional view along Y-Y in  FIG. 4 ; 
       FIG. 6  is an exemplary embodiment of a runners assembly according to  FIGS. 4 and 5 ; and 
       FIG. 7  is a partial-sectional perspective view of an exemplary embodiment of a roller set. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows a sketch of a disengagement system for actuating a clutch in the power train of a motor vehicle, between the engine and manual transmission. The principle of such a disengagement system is known from DE 10 2004 009832. Schematically depicted in  FIG. 1  is a clutch  1  with a pressure plate  2  as well as a clutch disc  3  and a counterpressure plate  4 . To engage the clutch, pressure plate  2  on counterpressure plate  4 , non-rotationally connected with a crankshaft (not depicted), is pressed so that clutch disc  3  interposed between pressure plate  2  and counterpressure plate  4  is non-rotationally and non-positively connected with a transmission input shaft (not depicted). Pressure plate  2  is connected with a disc spring  5 , which is depicted only schematically as a spring. Disc spring  5  is connected with a lever  7  via a pressing means  6 . Pressing means  6  ensures that disc spring  5  is rotatably mounted in a known manner about a clutch axis  9 —the clutch axis  9  is the rotation axis—about which the clutch rotates in operation, which in normal cases coincides with the axis of transmission input shaft as well as the crankshaft axis. Thus, in as far as the arrangement corresponds to the arrangement described to date in DE 10 2004 009832 based on the example depicted in  FIG. 1  and  FIG. 2  for actuating a clutch. Lever  7  is mounted on the one side  7 . 1  of the lever with a housing bearing  8  capable of swiveling about an axis  8 . 1  that projects from the drawing plane of  FIG. 1 ; on the other side  7 . 2 , it is connected with pressing means  6 . The housing bearing comprises a circular segment disc  16 , on which lever  7  is disposed so that fastening point  17  of the lever on circular segment disc  16  during rotation of the lever about axis  8 . 1  moves on a circular track. The connection between lever  7  and pressing means  6  can be formed such that radial displacement can occur based on clutch axis  9 . The radial displacement is necessary for compensation of a radial relative motion of lever  7  opposite to pressing means  6  during actuation of lever  7 . Lever  7  rests on a runner unit  10  that, as depicted in FIG. 1 of DE 10 2004 009832, for instance, consists of an arrangement of rollers which can be disposed in form of a triangle, wherein one of the rollers is in contact with lever  7  and the two other rollers rest on one essentially plane raceway  11 . In one embodiment, the raceway is fixed to a housing (not shown). For simplicity, runner unit  10  is depicted here as a circle. Runner unit  10  rests on lever  7  in a displaceable fulcrum  12 . Fulcrum  12  is displaced during displacement of runner unit  10  along a curved track  13 . Curved track  13  is formed by the side of lever  7  facing the runner unit  10 . Lever  7  in this respect, according to the sketch of  FIG. 1 , can be a rod or a disc with essentially constant thickness, however, it can likewise feature another arbitrary form, so that, for instance, curved track  13  features a form different from the side of lever  7  facing away from runner unit  10 . Runner unit  10  is displaceable via a spindle  14  by means of an electric motor  15 , rigidly mounted on the housing, in a radially displaceable manner relative to clutch axis  9  along the coordinate x. If runner unit  10  is displaced along the raceway  11 , in one of the two directions specified by coordinate x, then the axial point of pressing means  6  changes (based on clutch axis  9 ). For the axial point of pressing means  6 , a coordinate y is drawn in  FIG. 1 ; for the radial point of runner unit  10 , coordinate x is drawn accordingly. Zero points of both coordinates are first arbitrary; for coordinate x, the radially furthest, outwardly displaced point of rest point  12  of runner unit  10  can be assumed as zero point, for instance. This point is outlined in  FIG. 1  by means of a dashed line with designation x o . A point y o  of pressing means  6  belongs to point x o  of runner unit  10  or of rest point  12 . Should value x and hence the point of runner unit  10  be increased from value x o  in the direction of coordinate x, then pressing means  6 , starting from the direction of the coordinate, will be moved from a zero point y o , at the same time, pressure plate  2  will be moved towards counterpressure plate  4 , thus, the clutch will be connected. Point x o  of runner unit  10  in the present exemplary embodiment designates the disconnected point of the clutch. This therefore involves an actively pressed clutch. In principle, it is also possible in the same manner to operate a clutch to be disconnected actively, when it is connected at rest and is not yet disconnected. 
     FIG. 2  and  FIG. 3  show a principle sketch of a disengagement system according to the prior art in  FIG. 1  in further abstracted depiction. Lever  7  is rotatably mounted with housing bearing  8 . Runner unit  10  is connected with spindle  14  by means of a mount hub  18 . Mount hub  18  comprises an axis  19 , which, as is apparent in the depiction of  FIG. 3 , comprises two axles  19 . 1  and  19 . 2  disposed on both sides of mount hub  18  and for instance screwed or welded together with said axles. Roller sets  20 . 1  or  20 . 2  are respectively disposed on axles  19 . 1  and  19 . 2 . Roller sets  20 . 1  and  20 . 2  respectively comprise a runner with large diameter  21  and a runner with small diameter  22 . The runner with large diameter  21  rests on lever  7 , runner  22  with small diameter rest on raceway  11 . Raceway  11  has a width b, which is dimensioned such that it is wrapped around by runners with larger diameter  21  of roller sets  20 . 1  and  20 . 2 . The runners with larger diameter  21  wrap around raceway  11  and thus provide lateral guidance of roller sets  20 . 1  and  20 . 2  and thus of the entire runner unit  10 . Lever  7  rests respectively on runners  21 , the entire runner unit  10  rests on raceway  11  via runners with smaller diameter  22 . Clutch force Fy causes a corresponding normal force F N  in fulcrum  12  through the lever arm ratios between fulcrum  12  and the action of clutch force Fy or of the lever between fulcrum  12  and fastening point  17 . Assuming symmetrical geometrical dimensions, F N /2 acts respectively on runners with large diameter  21  and the corresponding counteractive force of F N /2 on runners with small diameter  22 . Thus, torque is generated about fastening points  23  of axles  19 . 1  and  19 . 2  with mount hub  18 . 
     FIGS. 4 to 6  show an exemplary embodiment of a lever system according to the invention or a runner unit  10  according to the invention. On the housing side, lever  7  rests on a housing bearing  8 . Runner unit  10  is moved by a spindle  14  and rests on a raceway  11 . The type of depiction otherwise corresponds essentially to the depiction of  FIG. 2 . 
     FIG. 5  shows a section according to Y-Y in  FIG. 4 . Runner unit  10  comprises two roller sets  20 . 1  and  20 . 2  that rest on idler rollers  25 . 1  and  25 . 2 , which are connected with idler roller axles  26 . 1  and  26 . 2  with mount hub  18 . Roller sets  20 . 1  and  20 . 2  are therefore not directly connected with mount hub  18  and comprise respectively a runner with large diameter  21 , which rest on lever  7 . A runner with small diameter  22 . 1  and  22 . 2  is disposed respectively on both sides of runners with large diameter  21 . In  FIG. 5  is the runner with small diameter, which is disposed between the respective runners with large diameter  21  and mount hub  18 , is provided with reference sign  22 . 2 ; the runner with small diameter, which is disposed on the runner with large diameter  21  facing away from mount hub  18 , is provided with reference sign  22 . 1 . The runners with small diameter  22 . 1  and  22 . 2  respectively rest on raceway  11 . Raceway  11  includes two cutouts  24 , which as depicted in  FIG. 5  run perpendicularly to the drawing plane. The runners with large diameter  21  of two rollers sets  20 . 1  and  20 . 2  will engage with cutouts  24 . When a force F N /2 is exerted as compressive force by lever  7  on one of runners with large diameter  21 , then a counteractive force F N /4 will be exerted by the two respectively assigned runners  22 . 1  and  22 . 2  of respective roller set  20 . 1  or  20 . 2 . This is depicted in the example of roller set  20 . 1  in  FIG. 5 . Apart from a deflection of axles  19 . 1  or  19 . 2 , on which the respective roller sets  20 . 1  or  20 . 2  are connected with mount hub  18 , no torque will be exerted by the normal force F N  arising from clutch force Fy on fastening points  23 . Cutouts  24  in raceway  11  provide a two-side guidance of roller sets  20 . 1  or  20 . 2 , since runners with large diameter  21  respectively engage with same, so that the runner with large diameter  21  partially projects into section  24  as is apparent in  FIG. 5 . 
     FIG. 6  shows a section according to X-X in  FIG. 4 . Roller sets  20 . 1  and  20 . 2  do not rest directly on mount hub  18 , but support themselves on idler rollers  25 . 1  and  25 . 2 , which are connected by idler roller axles  26 . 1  and  26 . 2  with mount hub  18 . Axles  19 . 1  and  19 . 2  are therefore not connected directly with mount hub  18 . Through the geometry of lever configuration, a clutch force Fy, a normal force F N , and a tangential force F T , as they are marked in  FIG. 4 , are constantly exerted on runner unit  10 . Force F T  is also outlined in  FIG. 6 . Through tangential force F T , roller sets  20 . 1  and  20 . 2 , on which tangential force F T  respectively act on the parts, are pressed against idler rollers  25 . 1   25 . 2 . In addition (not shown), axle  19 . 1 , for instance, can be connected with support axle  26 . 1  and axle  19 . 2  as well with support axle  26 . 2 , e.g., in form of a cage  29 . Half-tangential force F T /2 acts on either idler roller  25 . 1  or  25 . 2  respectively—when disposed symmetrically on spindle  14 . The preceding arrangement produces the only torque in fastening points  23 . 
   Runners with small diameter  22 . 1  and  22 . 2  and axis  19  on which they are located and axle  19 . 1  for roller set  20 . 1  and axle  19 . 2  for roller set  20 . 2  can be connected firmly, e.g., by either pressing or welding. The runner with large diameter  21  of respective roller set  20 . 1  or  20 . 2  is rotatably supported relative to respective axle  19 . 1  or  19 . 2 , so that runners with small diameter  22 . 1  and  22 . 2  are not rotatable about their own respective axis. However, the runners with small diameter  22 . 1  and  22 . 2  are rotatable relative to the runner with large diameter  21  of the respective roller set  20 . 1  or  20 . 2 . In principle, this arrangement can also be reversed, in that, the respective axle is firmly connected with the runner with large diameter  21  and runners with small diameter  22 . 1  and  22 . 2  are rotatably disposed relative to the axle. 
     FIG. 7  shows an exemplary embodiment of a roller set  20 . 1  or  20 . 2  in a three-dimensional depiction, in partial section. Axis  19  is pressed together with runners with small diameter  22 . 1  and  22 . 2 . A needle bearing  27  is disposed between runners with small diameter  22 . 1  and  22 . 2 , which carry the runner with large diameter  21 . In the exemplary embodiment of  FIG. 7 , runners with small diameter  22  comprise discs  28  respectively on the side facing the runner with large diameter  21 , which engage with cutouts  24  and take over lateral guidance of the respective roller set  20 . 1  or  20 . 2 . 
   REFERENCE SIGN LIST 
   
       
         1  clutch 
         2  pressure plate 
         3  clutch disc 
         4  counterpressure plate 
         5  disc spring 
         6  pressing means 
         7  lever 
         7 . 1 ,  7 . 2  side of the lever 
         8  housing bearing 
         9  clutch axis 
         10  runner unit 
         11  raceway 
         12  fulcrum 
         13  curved track 
         14  spindle 
         15  electric motor 
         16  circular segment disc 
         17  fastening point 
         18  mount hub 
         19  axis 
         19 . 1 ,  19 . 2  axles 
         20 . 1 ,  20 . 2  roller sets 
         21  runner with large diameter 
         22 ,  22 . 1 ,  22 . 2  runner with small diameter 
         23  fastening point 
         24  section 
         25 . 1 ,  25 . 2  idler rollers 
         26 . 1 ,  26 . 2  idler roller axles 
         27  needle bearing 
         28  discs 
         29  roller cage 
       X actuation distance of actuator 
       Y actuation distance of clutch 
       Fy clutch force 
       Fx actuating force 
       F N  normal force 
       F T  tangential force