Abstract:
A clutch device including a housing connected to a drive for rotation in common around an axis of rotation and fillable with a fluid; first friction elements connected to the housing by a first friction element carrier for rotation in common around the axis of rotation; second friction elements connected to a takeoff by a second friction element carrier for rotation in common around the axis of rotation; a piston element configured to exert a force so that the first and second friction elements frictionally engage each other; an abutment arrangement arranged on the first or second friction element carrier, the abutment arrangement providing a support for the first and second friction elements; and an elastic arrangement disposed in a path of force transmission between the piston element and the abutment arrangement and axially compressible when the piston element exerts the force on the first and second friction elements.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a clutch arrangement for a motor vehicle, including a housing arrangement, which is to be connected to a drive unit for rotation in common around an axis of rotation and which is or can be filled with fluid; a first group of friction elements, which is connected to the housing arrangement by a first friction element carrier for rotation in common around the axis of rotation; a second group of friction elements, which is to be connected to a takeoff element by a second friction element carrier for rotation in common around the axis of rotation; a piston element, by means of which the friction elements of the first friction element group and the friction elements of the second friction element group can be brought into frictional engagement, wherein an abutment arrangement is provided on the first friction element carrier or on the second friction element carrier to produce a supporting action for the friction elements upon which the piston element exerts its force. 
         [0003]    2. Description of the Related Art 
         [0004]    In these types of clutch arrangements, also known as wet-running clutches or wet-running plate clutches, it is known that, to improve the closing process, i.e., to provide a defined closing movement with exertion of the appropriate pressure by the piston element, a spring element designed as a disk spring can be provided. During the clutch-engaging process, this spring generates a pretensioning force between the piston element and the friction element upon which the piston element exerts its force. The piston element must move against this pretensioning action so that it can actuate the friction element and thus produce the frictional interaction between the various friction elements. This spring element, which generates little or no interaction between the piston element and the friction element upon which the piston element acts and thus provides little or no force which could help engage the clutch, leads to the problem that, because of its closed, ring-like shape, it impairs the ability of the fluid to flow through the housing arrangement containing the various friction elements. Problems can therefore arise with respect to the cooling of the friction elements to be achieved by the circulation of the fluid. 
       SUMMARY OF THE INVENTION 
       [0005]    An object of the present invention is to provide a clutch arrangement for a motor vehicle in which the closing process of the clutch can be improved without impairing the ability of the fluid to flow through the housing arrangement. 
         [0006]    This object is accomplished according to the invention by a clutch arrangement for a motor vehicle, including a housing arrangement, which is to be connected to a drive unit for rotation in common around an axis of rotation and which is or can be filled with fluid; a first group of friction elements, which is connected to the housing arrangement by a first friction element carrier for rotation in common around the axis of rotation; a second group of friction elements, which is to be connected to a takeoff element by a second friction element carrier for rotation in common around the axis of rotation; a piston element, by means of which the friction elements of the first friction element group and the friction elements of the second friction element group can be brought into frictional engagement. An abutment arrangement is provided on the first friction element carrier or on the second friction element carrier to produce a supporting action for the friction elements upon which the piston element exerts its force. An elastic arrangement which is axially compressible when force is exerted on the friction elements by the piston element is provided in the path along which the path of force between the piston element and the abutment arrangement. 
         [0007]    In the inventive design of a clutch arrangement, therefore, the elastic effect is integrated directly into the force-absorbing path between the piston element and the abutment arrangement. No additional spring element, i.e., no spring element acting in parallel with the piston element, is required, which means that it is also possible to avoid the interference with the ability of the fluid present in the housing arrangement to flow around the friction elements. 
         [0008]    For example, the elastic arrangement can comprise at least one cup-like shielded friction element of the first friction element group and/or of the second friction element group. Through this cup-like shielded design, each friction element shielded in this way is axially compressed when a compressive force is exerted on it and thus provides a counteracting force. 
         [0009]    It is preferable for all the friction elements of the first friction element group or all the friction elements of the second friction element group to have this cup-like shielding. In this way, the elastic effect of a plurality of friction elements becomes additive, so that each individual friction element with cup-like shielding needs to be shielded to only a comparatively minor extent; nevertheless, through the sum of the individual elasticities, a comparatively large amount of axial elasticity can be integrated into the groups of friction elements. 
         [0010]    In an especially advantageous embodiment, it is proposed that the friction elements of the first friction element group or the friction elements of the second friction element group have friction linings on both axial sides and that the minimum of one cup-like shielded friction element is a friction element with friction linings. 
         [0011]    The abutment arrangement can comprise an axially elastic, ring-shaped element, which is supported by way of an axial locking element on a friction element carrier and which supports the friction elements in the axial direction. This ring-shaped element then forms at least part of the elastic arrangement. 
         [0012]    In another variant of the inventive clutch arrangement, a friction element of the first friction element group or of the second friction element group comprises two disk parts, where a first disk part is essentially flat and provides a friction surface, and where the second disk part is designed with cup-like shielding and is supported axially by way of an axial locking element on a friction element carrier and thus forms at least part of the elastic arrangement. 
         [0013]    The piston element, furthermore, can actuate the friction elements by way of a wavy, axially elastic ring-shaped element, which then forms at least a part of the elastic arrangement. This ring-shaped element can be connected essentially nonrotatably to a friction element carrier, to which a friction element also in contact with this ring-shaped element is connected essentially nonrotatably. Only an axial supporting action is therefore produced between this friction element and the ring-shaped element in contact with it, i.e., no circumferential movement is produced. 
         [0014]    Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The present invention is described in greater detail below with reference to the attached drawings: 
           [0016]      FIG. 1  shows a partial longitudinal cross section through a clutch arrangement; 
           [0017]      FIG. 2  shows a partial cross section of a friction element used in the clutch arrangement of  FIG. 1 ; 
           [0018]      FIG. 3  shows an enlarged view of part of an alternative clutch arrangement in isolation; 
           [0019]      FIG. 4  shows a view, corresponding to  FIG. 3 , of another alternative embodiment; and 
           [0020]      FIG. 5  shows a view, corresponding to  FIG. 3 , of another alternative embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]      FIG. 1  shows a clutch arrangement, designated overall by the reference number  10 . This arrangement comprises a housing arrangement  12  with a housing shell  14  on the engine side, which is connected nonrotatably by way of a connecting arrangement  16  to a crankshaft or the like, acting as a drive element. Radially on the inside, the engine-side housing shell  14  is permanently connected to a housing hub  18  by welding, for example. This housing hub  18  can be supported radially on the drive element. The housing arrangement  12  also comprises a gearbox-side housing shell  20 , which is permanently connected radially on the outside by welding to the engine-side housing shell  14  and which, radially on the inside, is permanently connected by welding to a drive hub  22 , which, in the assembled state of a drive train, engages in a gearbox, where it can drive a fluid pump. 
         [0022]    The radially outer area of the housing shell  14  forms a first friction element carrier  24 . The friction elements  26  of a first friction element group  28  are connected nonrotatably to this carrier  24  by engagement between sets of teeth but are able to shift position axially with respect to the carrier. A second friction element carrier  30  is connected by way of a torsional vibration damper arrangement  32  to a takeoff hub  34 , which is connected nonrotatably in turn to a takeoff element  36  such as a gearbox input shaft by engagement between sets of teeth. Friction elements  38  of a second group  40  of friction elements are connected nonrotatably by engagement between sets of teeth to the second friction element carrier  30  but are able to shift position axially with respect to the carrier  30 . It can be seen that, in this arrangement, the friction elements  26  of the first friction element group  28  and the friction elements  38  of the second friction element group  40  alternate with each other. 
         [0023]    When axially displaced, the radially outer area of a piston element  42 , which is supported on the housing arrangement  12  but is free to move in the axial direction, can press the friction elements  26  and  38  axially against each other, where an abutment arrangement  44  provides a support function, which produces a reactive force. This abutment arrangement  44  comprises a locking ring  46  attached to the first housing shell  14 , i.e., to the first friction element carrier  24 . A disk element  48 , which acts as a friction element  26  of first friction element group  28 , is supported axially against this ring. 
         [0024]    So that torque can be transmitted from the housing arrangement  12  to the takeoff hub  34 , the piston element  42  must therefore be shifted to the right in the diagram according to  FIG. 1 , so that it exerts force on the first friction element  26  of first friction element group  28  and thus pushes it against the adjacent friction element  38  of the second friction element group  40 . In this way, the friction elements  26 ,  38  are pressed against each other while producing the supporting action of the abutment arrangement  44  and thus provide the torque-transmitting function as a result of the frictional interaction thus obtained. 
         [0025]    It can also be seen in  FIG. 1  that the friction elements  26  of the first friction element group  28  are made as essentially flat disk parts, fabricated out of sheet metal, for example. The friction elements  38  of the second friction element group  40  comprise a disk-like friction lining carrier  50 , similar in design, for example, to the friction elements  26 . This carrier  50  carries ring-like or ring segment-like friction linings  52 ,  54  on both axial sides. A friction element  26  of the first friction element group  28  not equipped with friction linings thus always alternates with a friction element  38  of the second friction element group  40  equipped with friction linings  52 ,  54 . 
         [0026]    A cross section of a friction element  38  of the second friction element group  40  of this type is shown on an enlarged scale in  FIG. 2 . It is possible to see the ring-like friction lining carrier  50 , which has a set of teeth  56  on its inside circumference to establish the nonrotatable connection with the second friction element carrier  30 . In its ring-like area radially adjacent to the set of teeth  56 , this friction lining carrier  50  carries the friction linings  52 ,  54  on both axial sides. These linings  52 ,  54  can be attached by means of an adhesive, for example. It can also be seen that the friction element  38  is not flat but rather shielded in a cup-like manner when no force is being exerted on it. This means that this friction element  38  is at an angle to the plane E, which is essentially orthogonal to the axis of rotation A. Under axial load, that is, when a clutch-engaging operation is performed, the radially outer area of a friction element  38  of this type comes into contact with the immediately adjacent friction element  26  of the first friction element group  28 , whereas the radially inner area comes in contact with the friction element  26  on the other axial side. Because of the inherent elasticity of the friction lining carrier  50 , a friction element  38  of this type is compressed and generates a counterforce when the piston element  42  presses against it. Because preferably all of the friction elements  38  of the second friction element group  40  are provided with this type of cup-like shielding, their elasticities are additive, so that the axial elasticity providing the previously mentioned counterforce is integrated into the path of force absorption between the abutment arrangement  44 , especially the locking ring  46  of that arrangement, and the piston element  42 . As a result, the piston element  42  will act against a defined elasticity or counterforce when the clutch is being engaged, and this significantly increases the precision with which these types of clutch-engaging operations and the corresponding clutch-releasing operations can be conducted. The friction elements  38  of the second friction element group  40  therefore represent here an elastic arrangement acting in the path of absorption between the piston element  42  and the abutment arrangement  44 . 
         [0027]    It should be pointed out here that it would also be possible, of course, for the friction elements  26  of the first friction element group  28 , i.e., the friction elements without friction linings, to have the cup-like shielding and/or to provide friction linings also or only on the friction elements  26  cooperating with the first friction element carrier  24  and possibly to design these friction elements  26 , if desired, with cup-like shielding. 
         [0028]    A modified embodiment of a clutch arrangement  10 , the design of which can be basically the same as that shown in  FIG. 1 , is illustrated in  FIG. 3 . It can be seen here again that there are two friction element carriers  24 ,  30 , the friction elements  26 ,  38  of the two friction element groups  28 ,  40  being connected nonrotatably to these carriers. 
         [0029]    In embodiment shown in  FIG. 3 , the disk element  48 , which can be interpreted as the last axial friction element  26  of the first friction element group  28  and also as a part of the abutment arrangement  44 , is divided into two separate disks  60 ,  62 . The separate disk  60  cooperating with a friction element  38  of the second friction element group  40  can be flat and can have exactly the same design as, for example, the other friction elements  26  of this friction element group  28 . The other separate disk  62  can then have the cup-like shielded design, so that in particular the radially inner area of the separate disk  60 , i.e., the area radially farther away from the friction element carrier  24 , is supported. When the piston element  42  exerts force on it, the separate disk  62  can “give” axially and therefore provide the previously mentioned elasticity. The separate disk  62  can also have exactly the same design—except for the cup-like shielding—as the other friction elements  26  of the first group  28 , which can provide a cost advantage in terms of manufacturing. 
         [0030]    In the case of the design variant shown in  FIG. 4 , the abutment arrangement  44  comprises a ring-like, axially elastic support element  64 . The area of this element farther away in the radial direction from the friction element carrier  24 , that is, its radially inner area, supports the last axial friction element  26  of the first friction element group  28 , and radially on the outside, where, for example, it is connected nonrotatably to the friction element carrier  24 , it is supported axially against the locking ring  46 . This ring-like support element  64  can be shaped out of sheet metal, but it can also be designed as a ring-shaped part fabricated by turning. In this variant, the friction elements  26  and  38  of the two groups  28  and  40  can then all be essentially flat, that is, without any cup-like shielding. 
         [0031]      FIG. 5  shows a design variant in which the elastic arrangement present in the path of force absorption between the piston element  42  and the abutment arrangement  44  is provided essentially by a ring-like, circumferentially wavy spring element  66 . This is supported against the first axial friction element  26 , that is, the element  66  immediately adjacent to the piston element  42 , and its radially outer area is engaged for rotation in common with the friction element carrier  24 . The force exerted by the piston element  42  on this ring-like spring element  66 , which there has the design of a wave washer or spring washer, acts on the crests of the waves facing away from the directly adjacent friction element  26 , and thus the wave crests facing the directly adjacent friction element  26  are pressed against that element  26 . An axial elasticity can thus also be integrated in this way into the path of force transmission between the piston element  42  and the abutment arrangement  44  without producing any frictional interaction between the ring-like spring element  66  and the friction element  26  upon which it acts. 
         [0032]    It should be pointed out in conclusion that, of course, the various aspects of providing an elastic arrangement in the path of force between the piston element and the support arrangement can be combined with each other, and/or the cooperation with the two friction element carriers  24 ,  30  can be reversed. In the case of the exemplary embodiments shown here, however, it is especially advantageous for the piston element  42 , which can be connected essentially nonrotatably to the housing arrangement  12 , to cooperate directly with a component which is also connected nonrotatably to the housing arrangement  12 , that is, for example, with a friction element  26  or, in the case of the embodiment according to  FIG. 5 , with the ring-like spring element  66 . It is also advantageous for the abutment arrangement  44  to be effective with respect to the housing arrangement  12 , as a result of which the friction element carrier  30  connected via the torsional vibration damper arrangement  32  to the takeoff hub  34  can be kept essentially free of axial forces. 
         [0033]    Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.