Abstract:
A device for actuating a friction clutch with automatic adjustment. An actuating movement for engaging and disengaging the clutch is transmitted to a pressing component. The adjusting device includes a sensing component that is biased in the direction of an adjusting movement and compensates for sensing play that occurs as a result of wear when the clutch is engaged, and that compensates for play that occurs when the clutch is disengaged after compensation of the sensing play in the movement transmission between the actuating component and the transmission component. When the clutch is engaged and wear is present, the sensing component moves out of contact against a spring component which, when the clutch is engaged and wear is present, comes into contact against a stop before the fully engaged state of the clutch is reached.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of International Application Serial No. PCT/DE2007/001436, having an international filing date of Aug. 16, 2007, and designating the United States, the entire contents of which is hereby incorporated by reference to the same extent as if fully rewritten. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a device for actuating a friction clutch with automatic adjustment. 
     2. Description of the Related Art 
     From DE 10 2004 019 809 A1 a twin clutch assembly with automatic adjustment is known. The adjustment devices, which are associated with each particular clutch, are identical and respectively include a leaf spring shaped capture component, which is supported at a force transmission element  44  through a sensing or arresting element and through adjustment elements disposed parallel thereto, wherein said force transmission element is engaged by the transmission component. It is particular for the described adjustment devices that the sensing component, as well as the adjustment component, are disposed in the force transmission path from the leaf spring shaped capture element, actuated by the actuation element, to the force transmission element, so that the adjustment movements, which depend on the deformation or tilting of the leaf spring shaped capture element are coupled in a complex manner. 
     It is an object of the present invention to improve a device of said type, so that safe wear compensation is provided with a simple configuration. 
     SUMMARY OF THE INVENTION 
     According to the invention the object is accomplished by a device for actuating a friction clutch with automatic adjustment, which includes an actuation component whose actuation movement is transmitted to a force transmitting component through an adjustment device. An actuation movement for engaging and disengaging the clutch can be transmitted by the force transmitting component to a pressing component. The adjustment device includes a sensing component, which is biased in the direction of an adjustment movement, wherein when the clutch is disengaged the sensing component compensates a sensing clearance which occurs due to wear. The adjustment device includes an adjustment component which is biased in the direction of an adjustment movement, which adjustment component when the clutch is disengaged compensates a clearance which occurs in the transmission of the movement between the actuation component and the force transmitting component after the sensing clearance has been compensated. The sensing component is not initially included in the transmission of the movement from the actuation component to the force transmitting component, and the sensing component is disposed so that it comes clear by the amount of the sensing clearance from a contact with a spring element when the clutch is engaged and wear is present. The spring element contacts a stop when the clutch is being engaged and wear is present, before the clutch is completely engaged. 
     According to the invention a spring component is deformed by reaching a stop when the clutch is being engaged and wear is present, which creates a sensing clearance between the spring component and the sensing component, which is compensated by adjusting the sensing component. This changes the resting position, which the actuation component assumes when the clutch is being disengaged, so that a clearance, which occurs in the movement transmitted between the actuation component and the transmission component, is compensated by adjusting the adjustment component. The sensing component, as well as the adjustment component, is free of force under the respective clearances, so that their adjustment movements are being safely performed. 
     In one embodiment of the device according to the invention, the sensing component is disposed between the transmission component and the spring component, wherein the spring component, which is disposed at the transmission component, thereby comes into contact with a stop fixed to the housing when the clutch is being engaged, and the spring component comes clear from the sensing component when the required wear compensation is performed, so that the sensing clearance can be compensated by adjusting the sensing component. 
     Preferably, the spring component contacts the stop, which is fixed to the housing, with its side facing away from the sensing component when the clutch is disengaged. 
     Preferably, the adjustment component is disposed between the actuation component and the transmission component, wherein a clearance occurs in the movement transmitted between the actuation component and the transmission component after an adjustment of the sensing component, when the clutch is engaged and the actuation component is in its resting position, wherein the clearance can be compensated by adjusting the adjustment component. 
     In an embodiment of the device according to the invention, the adjustment component can be a lever, which is supported at a bearing carried at the housing, which lever imparts a pressing force through the adjustment component onto the transmission component in order to engage the clutch. 
     In another embodiment of the device according to the invention the actuation component is supported through the adjustment component at a clutch housing, and the sensing component contacts the actuation component at a distance from the adjustment component on the same side as the adjustment component, and furthermore it contacts the spring component fixed to the housing and contacts the housing, wherein the assembly is configured so that the sensing component comes clear from the actuation component during its engagement movement and the spring component comes clear from the sensing component by contacting a stop, which is configured at the transmission component, when the clutch is engaged and wear has occurred, so that the sensing component is adjustable for adjusting the sensing clearance. 
     The sensing component and the adjustment component are preferably configured by substantially annular components, which surround the axis of the clutch. The faces of the annular components are configured and interact with the opposed surfaces of the components interacting with those annular components, so that their effective axial length is a function of their angular position with reference to a rotation about the axis of the clutch. 
     The invention can be used for all types of wearing friction clutches. The device according to the invention, due to its simple and compact configuration, is suitable in particular for actuating a twin clutch assembly disposed in a parallel variable speed transmission, in particular for the start-up clutch of a dry twin clutch assembly. The adjustment device respectively adjusts the entire occurring wear; this means not only the wear of the friction linings, but also the wear at the contact points between the actuation members. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is hereinafter described in more detail in an exemplary manner with reference to schematic drawing figures, wherein: 
         FIG. 1  shows a sectional view of components of a friction clutch in a plane including the axis of the clutch; 
         FIG. 2  shows detail A of  FIG. 1 ; 
         FIG. 3  shows six different actuation states of components in order to illustrate the adjustment process; and 
         FIG. 4-6  show figures corresponding to  FIGS. 1-3  for illustrating another embodiment of the clutch according to the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     According to  FIG. 1 , a clutch whose axis is designated with X-X in  FIG. 1  comprises includes a housing  10  of which only a cover is shown. An actuation lever  14  is supported by a wire ring bearing  12  at the housing  10 , wherein through components of an adjustment device designated overall with by  16  said actuation lever actuates a pull member  18 , which is rigidly connected with a pressure plate  20 . By moving the pressure plate  20  upward according to  FIG. 1 , friction linings  22  of a clutch disc  24  come in frictional contact with the pressure plate  20  and with an intermediate plate  26  mounted to the housing  10 . 
     Through another actuation lever  28  another pressure plate  30  can be moved downward according to  FIG. 1 , so that another clutch disc  32  comes in frictional engagement with the intermediate plate  26  or with the pressure plate  30 . 
     Besides the two clutch discs  24  and  32 , all components mentioned above can be non-rotatably connected with the output shaft of an internal combustion engine. The clutch disc  24  can be non-rotatably connected with a first clutch shaft (not shown) and which is disposed within a hollow second clutch shaft (not shown), to which the clutch disc  32  can be non-rotatably connected. The actuation levers  14  and  28  can be actuated by release bearings, which are supported on the outer clutch shaft (not shown). 
     The configuration and the function of the twin clutch are generally known and are therefore not further described. 
     It should be appreciated that the components visibly disposed only in the sectional view on both sides of the axis X-X, are substantially disc- or ring shaped components which surround the axis X-X. 
     Subsequently, the adjustment device according to the invention is described with reference to  FIG. 2 , which shows detail A of  FIG. 1  in an enlarged scale. 
     It is evident that the transmission of movement is performed by the actuation lever  14 , e.g. an annular disc with invert protruding inwardly-extending spring tongues, onto the pull member  18  which is used as a movement component for transmitting the movement of the lever  14  onto a pressure plate  20  through an adjustment ring  34 , whose axial face, which contacts the pull member  18 , is configured as a ramp and interacts with respective ramp surfaces  36  configured at the pull member. The adjustment ring  34  is biased in the circumferential direction relative to the pull member  18  by springs (not shown) acting in the circumferential direction, so that the adjustment ring  34  rotates relative to the pull member  18  and relative to the actuation lever  14 , when the distance between the pull member  18  and the actuation lever is increased, so that through relative movement between the ramp surfaces zero clearance is maintained in the transmission of movement from the actuation lever  14  to the pull member  18 . 
     On the housing  10 , furthermore, a lower stop  38  is provided, at which a spring element  40 , which is mounted to the pull member  18  and is configured as a tension spring, contacts lower stop  38  in the illustrated disengaged position of the clutch. A sensing ring  42  is disposed between the spring element  40  and the pull member  18 , which is biased in a similar manner as the adjustment ring  34  by springs (not shown), for rotation in the circumferential direction, wherein said sensing ring springs are supported at the sensing ring  42  and at the pull member  18 . The contact of the sensing ring  42  at the pull member  18  is performed by ramp surfaces  44 . 
     According to the figure an upper stop  46  that is fixed to the housing is provided above the lower stop  38 . The function of said upper stop  46  will be described below. 
     Based upon  FIG. 3  an adjustment process with five states a)-f) is described below: 
     In state a), the clutch is disengaged. That means the actuation lever  14  is mostly pivoted counterclockwise and the pull member  18  according to the figure is in its lowest position, in which the spring element  40  contacts the lower stop  38 . 
     In state b), the clutch is being engaged by pivoting the actuation lever  14  clockwise, wherein the full contact pressure of the pressure plate against the clutch disc is not yet reached and the spring element  40 , which has come clear from the lower stop  38 , follows the movement of the pull member  18 . A state is illustrated in which the spring element  40  comes into contact with the upper stop  46 . 
     When the actuation lever  14  is actuated further for full engagement of the clutch, as shown in  FIG. 3   c , the spring element  40  is deflected by contact with the upper stop  46 , so that the sensing ring  42  separates from contact with the spring element  40  and becomes force free. The amount, by which the sensing ring  42  clears the spring element  40  depends on the wear of the clutch, and it becomes larger with increasing wear. 
     The clearance that occurs between the sensing ring  42  and the spring element  40  is reduced in the state d) by adjusting the sensing ring, which is free of contact forces and thus is rotatable with little friction, so that the clearance is safely compensated. The state d) in which the sensing ring  42  contacts the spring element  40  and the pull member  18  without clearance, is the fully engaged state of the clutch after the sensing clearance or the sensing gap has been compensated. 
     When the clutch is disengaged (state e)), the spring element  40  in turn comes into contact with the lower stop  38 , wherein the distance between the pull member  18  and the lower stop  38  is increased due to the adjusted sensing ring  42 . Thus, when the actuation lever  14  is in the disengaged position (same position as in state a)), a clearance between the adjustment ring  34  and the actuation lever  14  occurs, which is compensated by rotatably adjusting the adjustment ring  34  since hardly any forces are present. The state f) thus corresponds to the state a), in which no clearance exists at the contact surfaces of the rings, but the pull member  18  is adjusted upward overall in order to compensate for wear according to the figure. 
       FIG. 4  shows an embodiment of a clutch, which is revised relative to  FIG. 1  with respect to the adjustment device and the support of the actuation lever at the housing. 
     According to  FIGS. 4 and 5 , the actuation lever  14  is not supported on the housing  10  by a wire ring bearing  12  in this embodiment, like in  FIG. 1 , but it is supported by an adjustment ring  64 , which contacts the housing  10  through ramp surfaces  66  and which is biased by springs (not shown) relative to the housing  10  for rotation in the circumferential direction. 
     At the free end of the lever  14 , opposite to the contact point between the lever  14  and the pull member  18 , a sensing ring  72  is disposed which contacts the lower side of the actuation lever  14  with its outer radial surface and which contacts the housing  10  with its inner radial surface through respective ramp surfaces  74 . At the housing  10  a spring element  76  is mounted, which is configured as a tension spring that interacts with the sensing ring  72  and with a protrusion of the pull member  18 , which forms a stop  78  as described below. 
     The function of the assembly according to  FIGS. 4 and 5  is described in a similar manner as the function of the assembly according to  FIGS. 1 and 2  with reference to six states a) through f) shown in  FIG. 6 . 
     State a) illustrates the clutch in the disengaged state. The actuation lever  14 , which is in the disengagement position, contacts the adjustment ring  64  and it is forced by the pull member  18 , which is disposed in the disengagement position of the clutch, to contact the sensing ring  72  with its free end, wherein the sensing ring is supported at the housing  10 . 
     In order to engage the clutch, the actuation lever  14  is pivoted clockwise about its support location on the adjustment ring  64  (state b)). Its free end thus clears the sensing ring  72 , whose rotatability is restricted, however, by its contact with the spring element  76 . 
     When wear has occurred in the clutch, the actuation lever  14  can continue to move from the position according to b) to state c), in which the pull member  18  has moved upward far enough, so that the stop  78  contacts the spring element  76 , so that the spring element  76  is moved upward by the stop  78  and comes clear from the sensing ring  72 , which creates a sensing gap, which can be compensated by rotating the biased sensing ring  72  (state d)), so that, in turn, no clearance exists between the sensing ring  72  and the spring element  76 , which is then deflected upward according to the figure. 
     When the clutch is subsequently disengaged and the actuation lever  14  is moved back into its disengagement position (state e)), which brings the free end of the actuation lever into contact with the sensing ring  72 , which has been rotated relative to the state a), the adjustment ring  64  become force free, so that it can be readjusted due to its bias in the circumferential direction (state f) and the disengaged state of the clutch is reached without clearance and with wear compensation. 
     The invention, which is described with reference to two embodiments, facilitates reliable wear adjustment, wherein not only the wear of friction linings, but also the wear in the actuation system of the clutch is compensated. In principle, the adjustment can also compensate for tolerances between transmission and clutch, so that aligning the clutch disk in the transmission factory can be avoided. The described wear adjustment is not sensitive to the sagging of springs and dynamic influences.