Abstract:
The invention relates to a coupling device for establishing a couplable connection between two rotationally mounted machine parts, particularly a first shaft and a second shaft. To this end, the second shaft comprises a coupling ring that, on the inside, has tensioning bodies, which act against each another in pairs and which are arranged so they surround the shaft.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Applicant claims priority under 35 U.S.C. §119 of European Application No. 04007914.7 filed Apr. 1, 2004. Applicant also claims priority under 35 U.S.C. §365 of PCT/DE2005/000513 filed Mar. 18, 2005. The international application under PCT article 21(2) was not published in English. 
     DESCRIPTION 
     The invention refers to a clutch device for the couplable connection of a first shaft and a second shaft. 
     Clutches are known in a number of embodiments, and are described in technical literature, above all in machine element textbooks and clutch- and transmission atlases. 
     The object of the invention is to interconnect two rotatably mounted machine parts. 
     The clutch according to the invention, which is effective in both rotational directions, is a cone clutch with sprags, as are known from reverse locks, and freewheel- or override clutches, and are used as coupling elements. With sprags as coupling elements, the machine parts to be coupled can be coupled steplessly to one another in any optional rotational position. The characteristic of a positive clutch can be imparted to the torque transmission, since, depending upon the cone angle, with self-locking, the clutch can be constructed torsionally fixed, up to the breakage of the sprags or their surrounding parts. 
     With suitable matching of the cone angle and the axial shift force, a safety clutch can also be created, which begins to slip upon the exceeding of a predetermined maximum torque. 
    
    
     
       The invention is described in more detail with reference to exemplary embodiments in the drawing figures. In the drawings: 
         FIG. 1   a, b  show sectioned views A-A of a clutch according to  FIG. 2 , 
         FIG. 1   c  shows an enlarged view of  FIG. 2 , 
         FIG. 2  shows a first embodiment of a clutch, 
         FIG. 3  shows a further embodiment of a clutch with sliding sleeve, 
         FIG. 4  shows a further embodiment of a duplex clutch with sliding sleeve, 
         FIG. 5  shows a further embodiment of a double clutch with sliding sleeve. 
     
    
    
     The component parts of the clutch are shown in  FIG. 1 . The clutch comprises the outer clutch ring  1 , the shaft  2 , and the sprags  3  installed radially in between, which in an encircling cage  4  which is known per se from freewheels, are retained in recesses  5 , which are distributed evenly on the periphery of the cage  4 , and, by a spring element  6 , are in spragging readiness. The sprags  3 , in the described case, have, in the middle, inclined slots  7  for the holding of the encircling spring element  6  used in this embodiment, known per se from freewheels, which is supported on the right-hand edge  8  of the slots  7 , and presses radially on the sprags  3  with the adjusting force F A . 
     The force application point for F A  does not lie in the connecting lines  9 , between the outer and inner contact point of the sprags  3  with the associated clamping faces  10  and  11 , so that, in each case, a torque M ensues, which rolls the sprags  3  into spragging readiness. The sprags  3  are in pairs opposite one another, and are held in spragging readiness so that neither a right- nor a left-hand rotation of the clutch components  1  and  2  in relation to one another is possible. 
       FIG. 1   a  and  1   b  show an installed position of the sprags, rotated by 180°, and a spring element  6  with a larger diameter ( FIG. 1   a ), and also a spring element  6  with a smaller diameter ( FIG. 1   b ). 
     In  FIG. 1   a , with the clutch open, the sprags  3  are pressed against the clamping face  11  of the shaft  2 , with this being the appropriate embodiment if the shaft  2  is in the decoupled state. In  FIG. 1   b , the sprags  3  are retained in the clutch ring  1 , and make this embodiment universally usable. 
       FIG. 1   c  shows that the clamping faces  10  and  11  are exactly parallel, and form an angle α of from 0 to about 10° in relation to the rotational axis. The radial spacing in the clamping faces  10  and  11  is equal to the maximum sprag height, minus the required radial roll-in travel of the inner and outer engagement curves of the sprags  3 . 
     A stop  12  prevents the sprag cage  4  from axially sliding out. The coupling and decoupling of the two machine parts of the outer clutch ring  1  and the shaft  2 , takes place by displacement axially in relation to one another by the amount s. The amount s must be large enough until the sprag engagement curve comes out of contact with one of the clamping faces  10  or  11 . If L is this necessary clearance, then the amount s must be s ≧L/sinα. L consists of the radial roll-in travel of the sprags  3 , and the desired clearance between untensioned sprags  3  and clamping face. 
     The selection of the cone angle α is of vital significance for the shift performance of the clutch. The two pieces of operating data, axial shift force and shift travel, are in a reciprocal relationship to one another. In the general application case, the clutch is designed so that the axial shift force F s  is sufficient to overcome the adjusting force F A  of the springs on the sprags  3 , and to ensure there is a contact force F K  between engagement curve and clamping faces. F K  counteracts the adjusting forces F A  of the two clamping faces in relation to one another, and, in the first instance, depends upon the angle α. 
     The clutch, in general, is designed so that the clutch is self-locking, which is achieved with the current material pairing of steel on steel, with a coefficient of static friction of about μ=0.1 and, therefore, tan α&lt;0.1, i.e. α&lt;7°. 
     Since, in operation, the sprags mutually spread apart a little further during shock-like transmission of the rotational movement, the holding release force, with α &lt;7°, must be greater than F s . Angles of α≧7° are for clutches to be used with lower torques to transmit, with easy shiftability and short shift travels, but with greater shift force F s . 
     In the  FIGS. 2-4 , the clutches show the coupled state in the upper half of the illustration, and the decoupled state in the lower half of the illustration. In  FIG. 5 , the clutch shows the decoupled state in the upper half of the illustration, and the coupled state in the lower half of the illustration. 
     The simplest embodiment of a shaft clutch is shown in  FIG. 2 . The sprag ring  3 , with the inner-lying spring element  6 , is held in the shaft  13  by the outer clutch ring, and, by the stop  12 , is prevented from falling out. The shaft  13  is brought into clamping contact with the shaft  14 , by the amount S, by axial telescoping, and, by this, is coupled torsionally fixed. The axial distance S is dimensioned so that the clamping contact is neutralized with the drawing apart of the two shafts  13  and  14 , and a small clearance L ensues. 
     In  FIG. 3 , the two shafts  13  and  14  are immovable in relation to one another, and the coupling action is carried out by the sprags  3 , by means of the sliding sleeve  15 . The sliding sleeve  15  is operated externally in a known manner, and is axially movably mounted on the shaft  13  with positive locking. The other shaft  14  carries the mating clamping face  11 . 
     The possibility of coupling two rotating machine parts by their end faces, in a small installation space, is demonstrated in  FIG. 4 . The sliding sleeve  16 , on the clutch side, has an outer- and inner cone with the same cone angle α, and is rotatably mounted on the shift component  17 , which carries out the shift travel S mechanically, hydraulically, pneumatically, or electrically operated. 
     The two sprag rings  3  and  3 ′ are supported on the clamping faces  10  and  11  of the sliding sleeve  16 , once by the outer spring element, and once by the inner spring element  6  and  6 ′. The sliding sleeve  16  does not rotate in the decoupled position (lower half of the illustration). 
       FIG. 5  shows the arrangement and embodiment of the clutch if two different drives  20  and  21  in a narrow space are to be steplessly and smoothly connected, in turn, to a driven shaft  22 . In this case, the sliding sleeve  18 , which is mounted movably but torsionally fixed, for example, in a wedge connection on the drive shaft  22 , has a double cone  19 , and  19 ′, on the outside, and the driving machine parts  20  and  21  each have an inner cone, in which a sprag ring  3  and  3 ′ is retained in each case. The sliding sleeve  18  is axially moved by a shift rod  23 , exemplarily shown here, which is guided in the shaft  22 , and is rigidly connected to the sliding sleeve  18  by the plate  24 . 
     In the end positions of the shift rod  23 , the corresponding drive component  20  or  21  respectively is coupled to, and driven by, the shaft  22 . The shift rod  23  makes an overall axial movement of S, wherein at S/2 (middle position), the two clutch connections are disengaged, so providing the neutral position without a drive for the driving elements  20  and  21 . With this, the shift rod  23  has altogether three shift positions. The shift movement can also be initiated in the sliding sleeve  18  externally, with increased spacing of the drive elements  20  and  21 . 
     The clutch device can comprise one or more sprag rings  3 , which are in a row, one behind the other, on the same inner- and outer cone (not illustrated). 
     LIST OF DESIGNATIONS 
     
         
           1  Clutch ring 
           2  Shaft 
           3  Sprag 
           4  Cage 
           5  Recess 
           6  Spring element 
           7  Slot 
           8  Edge 
           9  Connecting line 
           10  Clamping face 
           11  Clamping face 
           12  Stop 
           13  Shaft 
           14  Shaft 
           15  Sliding sleeve 
           16  Sliding sleeve 
           17  Shift component 
           18  Sliding sleeve 
           19  Double cone 
           20  Drive component 
           21  Drive component 
           22  Shaft 
           23  Shift rod 
           24  Plate