Abstract:
A drive for an hybrid vehicle, having an electric machine situated in a housing and having a clutch that is provided with a release mechanism. The release mechanism is connected to a housing-mounted component, that is locked against rotation, via at least one damping element, the damping element absorbing multi-dimensional motions.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a drive for an hybrid vehicle as well as a clutch having a release mechanism. 
     BACKGROUND INFORMATION 
     German Laid-Open Patent Document DE 10 2006 016 133 A1 discusses that drives for hybrid vehicles are generally made up of an internal combustion engine, at least one clutch and an electric machine. A clutch is connected between the internal combustion engine and the electric machine, which is opened or closed depending on the operating strategy and the respective operating state. Clutches in vehicles driven by hybrid drives have to be more capable of taking loads than usual motor vehicle clutches, because of the increased number of operations that are created by the operating strategies in the hybrid vehicle. One possibility of increasing the service life provides that the release mechanism of the clutch in the clutch system be rotatably mounted, and supported on a housing part that is locked against rotation, which is spoken of as a cover-fastened release mechanism, as is discussed, for example, in German Laid-Open Patent Document DE 103 13 435 A1. 
     It is a disadvantage in such an embodiment of hybrid systems that drag torques are created by the bearings that are additionally required in the release mechanism and in the clutch system, by contrast to the usual release mechanisms that are fixed to the housing. At the contact location between the release mechanism and the housing, in the long run, these drag torques lead to wear and to damage that may impair the functioning of the drive system, and may finally lead to malfunction. 
     SUMMARY OF THE INVENTION 
     In order to remove these disadvantages, the exemplary embodiments and/or exemplary methods of the present invention provides a drive for an hybrid vehicle, whose electric machine is situated in a housing, and whose clutch is provided with a release mechanism that is supported in the clutch and, via at least one damping element, is connected in a torsion-proof manner to a component that is fixed to the housing 
     One advantage of a release mechanism that is fixed to the cover of a clutch in a drive of a vehicle, that is driven hybridly, is that forces that are created during the operation of the clutch, and their counterforce (action=reaction) are absorbed by the cover of the clutch&#39;s pressure plate and consequently remain in the clutch system. In the usual release mechanisms that are fixed to the housing, the forces created in response to operation are absorbed via the housing of the clutch, and the counterforces created thereby are passed on via the clutch and the crankshaft, and absorbed by the crankshaft bearings. Crankshaft bearings are usually designed as radial friction bearings, and are thus not designed for hybrid-specific requirements. 
     The cap bearing accommodated in the clutch pressure plate and the release bearing accommodated in the release mechanism are the cause of drag torques in response to a rotating motion of the clutch pressure plate. These torques and the tangential motions in the main load direction are advantageously absorbed via a lever of the release mechanism which is supported on a component that is fixed to the housing. Various form-locking connections are conceivable between the release mechanism and the component that is fixed to the housing, such as projections on the release mechanism and a corresponding negative geometry on the component that is fixed to the housing, for the purpose of absorbing motions and drag torques. 
     An end shield of an electric machine, that is situated directly at the clutch, is advantageously provided as the component that is fixed to the housing, for making the clutch disengaging gear torsion-proof. The utilization of component parts present in the drive system of the hybrid vehicle saves installation space and the costs of additional components. 
     Because of the highly dynamic behavior of the clutch, which comes about due to crankshaft motions, manufacturing-related axial eccentricities and residual imbalances, there are also created, in addition to the tangential motions, multi-dimensional relative motions between the disengaging gear fixed to the clutch pressure plate and the component that is fixed to the housing. In this context, acceleration forces occur which amount to a multiple of the forces that are absorbed statically. The relative motions cause wear between the lever and the component that is fixed to the housing, as well as high noise emission. According to the exemplary embodiments and/or exemplary methods of the present invention, these relative motions are absorbed by a damping element, in a manner that is free from wear and low in noise. 
     The damping element may be made of an elastomer, in particular of an elastomer of Shore hardness A 60. 
     According to the exemplary embodiments and/or exemplary methods of the present invention, the damping element is designed so that it is adjacent to the component that is fixed to the housing, and absorbs the motions created. The freedom from wear is given by a high coefficient of friction between the damping element and the component that is fixed to the housing, since the high coefficient of friction does not permit any relative motion between the damping element and the component that is fixed to the housing. 
     One exemplary embodiment provides that stops be developed on the end shield, between which the lever of the release mechanism engages. Depending on the type of production of the end shield, these may be cast on, screwed on or connected to the end shield in another manner. 
     In one advantageous specific embodiment, the damping element has a damping bead at the active areas with the stops, respectively, so as to obtain a better damping response by using more material. The damping element may be configured in such a way that, between the stops of the end shield and the damping element, there is a press fit, and thus a prestressing. 
     In one embodiment, the damping beads are connected to one another by crosspieces which make possible screwing together or pinning together the damping element with the lever of the release mechanism. The lever has suitable bores for this assembly. 
     An additional specific embodiment that is cost-effective and assembly-friendly provides that the damping element be developed as a tube having laterally attached damping. This specific embodiment is assembled by being turned upside down lightly onto the lever of the release mechanism. The geometry of the lever is developed by an encircling groove and by limiting steps in such a way that the damping element fits in optimally, and is radially fixed. 
     Exemplary embodiments of the present invention are depicted in the drawings and described in greater detail in the description below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an exploded drawing of a perspective representation of a clutch. 
         FIG. 2  shows a perspective representation of a cutout of an end shield and of a release mechanism. 
         FIG. 3  shows a perspective representation of a first specific embodiment of a damping element. 
         FIG. 4  shows a perspective representation of a second specific embodiment of a damping element. 
         FIG. 5  shows a perspective representation of a specific embodiment of a projection. 
         FIG. 6  shows a perspective representation of a mounted damping element according to the second specific embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The exploded drawing represented in  FIG. 1  shows the essential components of a coupling  1 . 
     A release mechanism  2  having a projection  6  is shown, which is supported in a cover  3  of a pressure plate  21 . Furthermore, the system of clutch  1  includes a flywheel  19  and a clutch disk  20 . 
       FIG. 2  shows the release mechanism  2  in greater detail. Projection  6  is formed by a lever that is radially projecting away from release mechanism  2 , to which a damping element  7  is fixed using connecting elements  9 . These may be screws or pins, for example. In the specific embodiment shown in FIG.  2 , a component  8 , that is fastened to the housing, is formed by an end shield of an electric machine, to which two stops  10 , that are at a distance from each other, are attached as one piece, between which damping element  7 , that is mounted on projection  6 , engages. Damping element  7  touches stops  10  via friction surfaces  11 , stops  10  preventing the twisting of release mechanism  2  in the tangential direction, as well as absorbing forces and torques of release mechanism  2 . The absorption of the forces and torques, as well as the securing from twisting in the tangential direction may also be performed by any geometrical shape which forms a form-locking connection between projection  6  and component  8 , fastened to the housing, via damping element  7 . 
     Housing-fastened component  8  may be made of metal, for instance, and produced by a casting method that makes possible the in-one-piece attachment of stops  10 . Stops  10  may alternatively also be connected by screws or rivets to housing-fastened component  8 . 
     A first specific embodiment of damping element  7  is shown in  FIG. 3 . Damping element  7  is formed in one piece of two damping beads  12 , directed parallel to each other, which are connected to each other by two crosspieces  13 . In this specific embodiment, damping beads  12  are semicircular in cross section, the rounded side being directed outwards in each case. Crosspieces  13  are attached at the flat inner side. Each of damping beads  12  has a hollow space, which is developed as a passage  22 , parallel to projection  6  of release mechanism  2  in the radial direction, and which is used for the improvement of the damping response. In one exemplary embodiment, passage  22  is developed in the same geometric shape as damping beads  12 . Other geometric shapes are also possible for passages  22  which improve the damping response, and so are damping beads  12  made of solid material. 
     Crosspieces  13  are developed to be rectangular and have a lower mass than damping beads  12  in the axial direction of release mechanism  2 . Crosspieces  13 , in the axial direction of release mechanism  2 , are attached to the flat inner side of damping beads  12  in such a way that they do not terminate at the upper and lower edges of damping beads  12 . A minimum distance is to be kept between crosspieces  13 , which enables putting through connecting elements  9 . The design of this embodiment is used for accommodating damping element  7  in projection  6  of release mechanism  2 , damping element  7  being pushed into the projection and being fixed to release mechanism  2  using screws or pins, for example. 
     One further specific embodiment is depicted in  FIGS. 4 to 6 . Damping element  7  is developed as a tube  14 , and has damping beads  12  at the sides, which are rounded off towards the outside. In damping beads  12  passages  22  are formed having a circular cross section, and being provided with an unmolding angle for its production. In this specific embodiment too, additional geometric cross sections are possible that are conducive to the functioning, as well as damping beads  12  made of solid material. Inner tube  14  of damping element  7  in  FIG. 4  has the same geometric shape as a groove  16  of projection  6  of release mechanism  2 , shown in  FIG. 5 . In this embodiment, what is advantageous is the simple assembly of damping element  7  by turning it upside down over projection  6 , which is sufficient without using additional connecting elements. In the specific embodiment shown in  FIG. 5 , on projection  6 , limiting steps  17 ,  18  are attached as one piece, which fix damping element  7  on release mechanism  2 , in the radial direction of release mechanism  2 . The inner cross section of tube  14  should be configured to be smaller than the outer cross section of groove  16 , for the improved retention on projection  6 . This ensures a close fit of damping element  7  on projection  6 , and improves the absorption of the forces and torques that occur. 
     The material of damping element  7  has damping properties and has a high coefficient of friction on friction surface  11  between damping element  7  and stops  10 . These properties may be fulfilled by elastomers, especially by elastomers having a Shore hardness of A 60. Damping elements  7  are produced, for instance, by injection molding, extruding or transfer molding.