Abstract:
A clutch unit including a housing fixed to a flywheel, in which two axially displaceable pressure plates are housed fixed to the housing to form a first and a second clutch, each provided with a clutch disk, whereby the clutches may be independently operated by means of lever arrangements, mounted to pivot on the housing, whereby each lever arrangement is connected to a pressure plate for opening and closing the corresponding clutch.

Description:
[0001]     This application is a continuation of prior International Application PCT/DE2006/0001666, filed Feb. 3, 2006. 
     
    
       [0002]     The invention relates to a clutch unit with a housing, which can be mounted to a flywheel, in which housing two press plates are received torque proof, relative to the housing, but axially displaceable, in order to form a first and a second clutch, a respective clutch disk is associated with each press plate, wherein the clutches can be operated independently from each other through lever arrangements, pivotably supported at the housing, wherein the lever arrangements are coupled to the respective press plates for opening and closing the respective clutches.  
       BACKGROUND  
       [0003]     Such clutch units, which are also called twin clutches, have become state of the art, e.g. through U.S. Pat. No. 3,760,918, U.S. Pat. No. 5,513,734, or U.S. Pat. No. 4,465,170.  
         [0004]     Such clutch units are being used in agricultural tractors or agricultural machinery among other applications. Thus one of the clutches is used for driving operations, and the other clutch is used for turning an additional drive on and off, through which additional equipment can be driven. Such additional equipment can be e.g. pumps, equipment to work the soil, harvesting equipment, or processing equipment for the harvested material.  
       SUMMARY OF THE INVENTION  
       [0005]     In accordance with an embodiment of the present invention, the present invention provides clutch units of the kind mentioned above, which are very reliable, and which are simple and compact in construction.  
         [0006]     In accordance with various embodiments of the present invention, this may be accomplished by the first clutch facing the flywheel being locked in non actuated state through a disk spring, compressed between its press plate and the housing, which is located axially between the actually adjacent press plates, whereas the second clutch provided on the side of the first clutch, facing away from the flywheel, is open in non actuated state, and forced locked through a force, transferred into the clutch unit from the outside, through its lever arrangement, wherein the lever arrangement of the second clutch is coupled with the associated press plate via axially operating pull elements, and between these pull elements and this press plate, at least one spring element is compressed, which has a predetermined preload, when the second friction clutch is opened, and which goes through an additional elastic deformation when this second clutch is closed.  
         [0007]     The almost axially adjacent arrangement of the two press plates allows a compact design, at least in axial direction, which is particularly due to the fact that only the disk spring may be disposed between the two said press plates. Furthermore, such a design of the clutch unit allows an axial overlap of areas of the press plates.  
         [0008]     An additional advantage of the designed clutch unit may be that the clutch, which is forced closed, may be used for additionally driving ancillary equipment, so that in case of a failure of the operating system, forcing the clutch closed, the clutch can open independently. Thereby, driving the ancillary equipment, examples for which have already been discussed, may be interrupted. The vehicle equipped with the clutch unit, however, may still be driven. Through the actual automatic decoupling of the power takeoff drive, a high level of operational safety is provided, since the engine driving the clutch unit does not have to be turned off.  
         [0009]     The minimum torque, which may be transferable by the second clutch, is determined through the preload of the at least one spring element.  
         [0010]     In accordance with certain embodiments of the present invention the layout of the clutch unit may be such that the levers of the first clutch are coupled with the respective press plate through pull elements. The layout of the clutch unit may thus be provided, so that the levers of both lever arrangements form levers with two arms. These two arm levers may thus be coupled through a respective radial external area with their associated pull elements through a respective joint. Radially within this joint, the levers may be pivotably supported at the housing. The radially interior areas of the levers may be actuated by an actuating system, which may be provided as a hydraulic, electric, or numeric system. The operating systems, however, may be comprised of a combination of various actuating systems, thus e.g. they may be provided electro-hydraulic, electro-pneumatic or hydro-pneumatic, etc.  
         [0011]     The at least one spring element, compressed between the pull elements and the press plate of the second clutch, may e.g. be formed by a component provided as a disk spring. Such a component may thus be designed, so that the force, generated by it, remains substantially constant, also over the additional elastic deformation, effected during the closing of the second clutch. In an advantageous manner, however, several coil springs may be used for forming a resulting spring element, at least one of which may be disposed between a respective pull element and the associated pressure plate. Such a preloaded coil spring is axially supported, on the one hand, at the pressure plate, and, on the other hand, at a pull element. The spring element or the coil springs may be thus disposed on the side of the associated press plate, facing away from the levers of the second clutch.  
         [0012]     When closing the second clutch, its pull elements may be axially displaced relative to the respective pressure plate by a limited amount against the effect of the coil springs.  
         [0013]     In accordance with certain embodiments of the present invention, the layout of the clutch unit may be such that, when the pull elements of the second clutch have an axial stop on the side of the associated press plate, facing away from the compressed spring element or the coil springs, the stop interacting with this pressure plate and limiting the unloading of the spring element, or the coil springs, when opening the second friction clutch. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     Further useful design- and functional features of a clutch unit, according to the invention, are described now with reference to the following figures.  
         [0015]     It is shown in:  
         [0016]      FIG. 1 a  plan view of a clutch unit; and  
         [0017]      FIG. 2 a  sectional view, along the line II-II of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION  
       [0018]     The clutch unit  1 , shown in  FIGS. 1 and 2 , forms a so-called twin clutch  2 , comprising two clutch disks  3  and  4 , which can be connected with different shafts, which are to be driven, and thus, through an internal hub teething  3   a ,  4   a . The clutch unit  1  comprises a first clutch  5  and a second clutch  6 , which can be operated independently from each other, through a first lever arrangement  7 , and a second lever arrangement  8 . As can be seen from  FIG. 1 , each lever arrangement  7  and  8  in the shown embodiment comprises three levers  9  and  10 . The levers  10  are provided as shaped sheet metal parts, whereas the levers  9  are provided as forged or cast parts. From  FIG. 1 , it is evident, that the levers  9  and  10  are disposed in an alternating manner in circumferential direction.  
         [0019]     As can be seen from  FIG. 2 , the clutches  5  and  6  each have a press plate  11  or  12 , which can be axially moved relative to an opposite press plate  13  or  14 , through the associated levers  10  or  9 , for opening and closing the clutches  5  and  6 . Through moving the press plates  11  and  12 , the friction liners of the clutch disks  3  and  4  are either unloaded, or clamped for torque transfer between the friction surfaces of their respectively associated press plates  11 ,  12 , and the opposite press plates  13  and  14 . The two press plates  11  and  12  are axially adjacent.  
         [0020]     In the shown embodiment, the opposite press plate  13  of the friction clutch  5  is formed by a flywheel  15 , which can be connected with the output shaft of an engine. The opposite press plate  14  is directly formed through a housing  16 , which can be connected with the flywheel  15 , and thus preferably through threaded connections. Therefore, the housing  16  has several axial threaded openings  17 , distributed over the circumference, which are visible in  FIG. 1 .  
         [0021]     As becomes apparent from  FIG. 2 , the two press plates  11  and  12  are axially received in the housing  16 , and the press plate  11  is axially loaded in closed position by the energy storage disposed axially between the press plates, provided as a disk spring  18 . The clutch  5  is thus closed in non actuated state. Hereby, the clutch spring  18  is supported in the shown embodiment, through its outer rim  18   a  at the housing  16 , and axially loads the press plate  11  with its radial inner areas  18   b  in the direction of the opposite press plate  13 . The axial dislocation of the press plate  11  is performed via the levers  10 , which are operably connected to the press plate  11  through a respective pull element, formed as a pull rod  19 . The pull rod  19  has a pivot bearing  20 , relative to the associated lever  10 . The lever  10  is radially supported within this pivot bearing  20 , at the housing  16 , through a pivot bearing  21 . On the radial inside, the levers  10  form loading areas  22  for an actuation element, as e.g. a so-called lay out bearing, or operating bearing. Due to this arrangement, these levers  10  each form a so-called two-arm lever, wherein the one lever arm is formed by the radial distance between the pivot axes of the pivot bearings  20  and  21 , and the second lever arm is formed through the radial distance of the operating areas  22  relative to the axle of the pivot bearing  21 . For opening the friction clutch  5 , the actuating areas  22  are actuated to the left, whereby the press plate  11  is pulled into the other axial direction via the pull rods  19 , thus to the right.  
         [0022]     As can be seen from  FIG. 2 , the levers  9  also each have an operating area  23  on the radial inside, a pivot support  24  on the radial outside for a pull element  25 , as well as, a pivot bearing  26  provided radially in between, which is carried by the housing  16 . Thus the levers  9  form so-called two-arm levers, similar to the levers  10 .  
         [0023]     For forming the pivot joints  21  and  26 , the housing  16  has so-called bearing supports  27 ,  28 , which are visible in  FIG. 1 . In the shown embodiment, the bearing supports  27  and  28  are formed by two respective axially protruding housing walls or housing cams  27   a ,  27   b  or  28   a ,  28   b , which are offset in parallel to each other, and receive one respective lever  9  or  10  between each other. The bearing cams  27   a ,  27   b ,  28   a ,  28   b , and the respectively associated levers  9  and  10  have indentations for receiving a pivot axis  29  or  30 .  
         [0024]     Between the levers  9 ,  10  and the housing  16 , hairpin springs or spring clips  31 ,  32  are compressed, which force the levers  9 ,  10  into a defined position.  
         [0025]     The pull elements  25 , which are also formed by pull rods, have an axial support  33 , which is formed here by two adjustable nuts. The stop  33  is disposed on the side of the press plate  12 , facing the opposite press plate  14 . On the side of the press plate  12 , facing away from the stop  33 , the pull elements  25  have a second stop or a support  34 , which also comprises a nut in the shown embodiment. Between a second stop  34  and the press plate  12  an energy storage is clamped, which is formed here respectively through at least one coil spring  35 . The second clutch  6 , due to the nature of its kinematical design, is open when the levers  9  are not actuated. Thus, this means that this second clutch  6  is forced closed through a force transferred into the clutch  6  through the actuation areas  23 . In the open state of the second clutch  6 , the preload force of the springs  35 , which is set to a predetermined value, is received by the stops  33 , whereby the defined position, illustrated in  FIG. 2 , between the particular components of the second clutch  6 , is assured. For closing the second clutch  6 , the actuation areas  23  are actuated towards the left, whereby the levers  9  are pivoted around the pivot supports  26 , so that the press plate  12  is pulled to the right via the pull rods  25 . As soon as the friction liners of the clutch disk  4  are clamped between the friction surfaces  12  of the press plate, and the opposite press plate  14 , and the operating areas  23  are furthermore displaced to the left by a certain amount, also the coil springs  35  are compressed between the second stop  34  and the pressure plate  12 . This is due to the fact that the pull rods  25  are pulled to the right by the levers  9 . The closing force of the second clutch  6  is thereby determined by the preload and the additional, comparatively small, compression of the springs  35 , which is additionally effected, when the clutch  6  is being closed.  
         [0026]     The clutch unit  1  is constructed, so that the first clutch  5  forms the said drive clutch, through which the vehicle is moved. The first clutch  5  thus serves for shifting the gears of the drive transmission. It is evident from  FIG. 2 , that the clutch disk  3  has at least one rotation oscillation damper  3   a.    
         [0027]     The second clutch  6  serves e.g. in tractors or multipurpose vehicles for driving auxiliary equipment, as e.g. pumps, harvesting, and/or ground working equipment etc. The clutch disk  4  in the shown embodiment is provided as so-called rigid clutch disk, thus without a damper.  
         [0028]     The embodiments are not to be perceived as restrictions of the invention. Furthermore, in the context of the present embodiment, various variations or modifications are possible; in particular, such variations, which can be formed through combinations or changes, of features, or elements, or process steps, which are included in the general description, and in the description of the figures, and which are described in the claims and included in the drawings.  
       DESIGNATIONS  
       [0000]    
       
           1  Clutch unit  
           2  Twin clutch  
           3  Clutch disk  
           3   a  Inner teething of hub  
           4  Clutch disk  
           4   a  Inner teething of hub  
           5  First clutch  
           6  Second clutch  
           7  First lever arrangement  
           8  Second lever arrangement  
           9  Lever  
           10  Lever  
           11  Press plate  
           12  Press plate  
           13  Opposite press plate  
           14  Opposite press plate  
           15  Flywheel  
           16  Housing  
           17  Axial threaded openings  
           18  Disk spring  
           18   a  Disk spring outer rim  
           18   b  Disk spring radial inner area  
           19  Pull rod  
           20  Pivot support  
           21  Pivot support  
           22  Actuation area  
           23  Actuation area  
           24  Pivot support  
           25  Pull element  
           26  Pivot support  
           27  Bearing support  
           27   a  Protruding housing lobes  
           27   b  Protruding housing lobes  
           28  Bearing support  
           28   a  Protruding housing lobes  
           28   b  Protruding housing lobes  
           29  Pivot axis  
           30  Pivot axis  
           31  Spring clip  
           32  Spring clip  
           33  Axial stop  
           34  Second stop or support  
           35  Coil spring