Abstract:
A release device for a friction clutch, including an actuator for axially actuating the friction clutch, the actuator being designed to be hydraulically actuated by a fluid, and a support element having an integrated securing point for supporting the actuator on a clutch bell. An axial connection for the hydraulic fluid can be provided in the support element. The invention also relates to the possibility of designing the support element as a single piece with the housing of the actuator.

Description:
INCORPORATION BY REFERENCE 
     The following documents are incorporated herein by reference as if fully set forth: International Application No. PCT/DE2012/000636, filed Jun. 21, 2012, and German Patent Application No. DE 102011107070.6, filed Jul. 11, 2011. 
     BACKGROUND 
     The invention relates to a release device. In particular the invention relates to a release device for axially actuating a friction clutch. 
     A friction clutch is used between a driving engine and a transmission of a motor vehicle, for example a lamella clutch operating in an oil bath, comprising a plurality of steel and friction lamellae, with one type of lamellae each being connected in a torque-proof fashion to a driven shaft of the driving engine and/or a drive shaft of the transmission. The lamellae are arranged alternating in the axial direction and are pressed against each other via a spring force such that here a friction-fitting connection develops, which connects the driven shaft of the driving engine with the drive shaft of the transmission in a torque-proof fashion. In order to release the lamellae clutch a release bearing is operated opposite the direction of force of the spring so that the friction-fitting connection between the lamellae is released and the torque-proof connection between the driven shaft and the drive shaft is interrupted. 
     Different embodiments of release devices are known for axially operating the release bearing. In one embodiment a hydraulic actuator is used, which is arranged annularly around the driven shaft of the driving engine. In a transmission with a dual clutch accordingly two lamellae clutches are installed, which can be operated independent from each other by hydraulic release devices arranged concentrically about the driven shaft of the driving engine. 
     SUMMARY 
     There is a need for a release device for a friction clutch with an improved assembly option to be used at a modern transmission under restricted spatial conditions. 
     This objective is obtained via a release device having one or more features of the invention. The preferred embodiments are described below and in the claims. 
     A release device according to the invention for a friction clutch comprises an actuator for axially actuating the friction clutch, with the actuator being implemented for hydraulic operation via a fluid, and a support element with an integrated securing point for supporting the actuator at a clutch bell. Here, an axial connection for the hydraulic fluid may be provided in the support element. Within the scope of the invention the option also develops to embody the support element in one piece with a housing of the release device. This way, in such an embodiment the housing forms a carrier housing. 
     The support element can therefore meet the objective of securing the release device at the clutch bell and simultaneously the guidance of the fluid. The release device can therefore be produced in an easier and more cost effective fashion. The fastening of the support element can lead to a separate assembly part, such as a clamping claw, becoming unnecessary. The fluid connection between the axial hydraulic connection and the corresponding hydraulic connection in the clutch bell can be established automatically during an assembly of the release device at the clutch bell. 
     Radial distances of the securing points from an axis of rotation of the friction clutch may be located outside a radial circumference of the friction clutch. This way, the clutch bell can be assembled when the friction clutch is already placed on the release device in the axial direction. This way, the release device can be assembled together with the friction clutch as a separately handled unit and perhaps be designed integrated with it. Such an arrangement of the release device is also called “cover-tight”. 
     In a preferred embodiment the release device is further embodied to release another friction clutch, independent from the other friction clutch, with the support element comprising another axial connection for fluids. 
     In a preferred embodiment the carrier element comprises an axial contact area for contacting the clutch bell in the area of the axis of rotation and the support element is shaped such that the securing points are axially separated each by a predetermined gap from the clutch bell when the contact area contacts the clutch bell such that the carrier element can be pre-stressed axially by approaching the securing points at the clutch bell in order to connect the axial connections in a fluid-tight fashion. 
     By pre-stressing the support element in the proximity of the axial connections it can be ensured that the connections are even fluid-tight when the fluid is pressurized in order to release one of the friction clutches so that the hydraulic pressure tends to axially distance the support element from the clutch bell. 
     In a preferred embodiment an axial spring element is provided for connecting the securing points with the clutch bell. The spring element is here designed such that it ensures that the predetermined pre-stressing of the support element is maintained and/or not exceeded. 
     In one embodiment the support element is embodied in one piece and comprises both the connections as well as the securing points and/or connection elements to the securing points. In another embodiment the support element comprises a hydraulic connection element to accept the connections and an essentially disk-shaped connection element, fastened at the connection element, to be fastened at the clutch bell. 
     The disk-shaped connection element can be produced in a cost-effective fashion, for example from sheet metal. The connection element may be formed from a light metal or from steel. Securing points may be provided both at the connector element as well as the connection element so that the connector element may be embodied in a compact and material-saving fashion, while the connection element can be sized weakly, because not all fastening forces of the connector element are guided through the connection element. This way production costs can be reduced. 
     By the separate connection element the construction space and/or the weight of the release device can be reduced. Further, savings can be achieved during the production of the release device. 
     In one embodiment a fitting device is provided to ensure an unambiguous rotational position of installation of the support element. This can prevent any faulty allocation and/or blockage of one of the hydraulic connections. 
     Adjacent angles between the securing points may be different from each other with regards to the axis of rotation. This way here a rotational position of installation of the support element and/or the connection element can be ensured. 
     Preferably the support element comprises a radial contact area for contacting the clutch bell in the proximity of the axis of rotation in order to ensure centering of the release device in reference to the clutch bell. A position of installation of the release device can this way be largely predetermined so that any play of installation can be reduced and a false position of installation can be prevented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is now explained in greater detail with reference to the attached figures. Shown are: 
         FIG. 1  is a longitudinal cross-sectional view through a release device; 
         FIGS. 2 to 4  are detail views of a release device of  FIG. 1 ; 
         FIGS. 5A  and B are perspective views of a support element of a release device according to  FIGS. 1 to 4 ; and 
         FIGS. 6A and 6B  are perspective views of a support element of a release device in another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a longitudinal cross-section through a release device  100 . The release device  100  is shown in the assembled state in a clutch bell  105 . Two friction clutches, particularly lamellae clutches operating in an oil bath, which can be axially actuated and/or released independent from each other via the release device  100 , follow the release device  100  towards the left and are not shown. 
     The clutch bell  105  represents a cup-shaped recess in the housing of an engine, particularly an internal combustion engine for driving a motor vehicle. The internal combustion engine extends from  FIG. 1  towards the right. A driven shaft of the internal combustion engine (not shown) extends from the side of the internal combustion engine towards the left through the release device  100  to the lamellae clutches. The lamellae clutches, the driven shaft, and parts of the release device  100  are arranged rotationally about an axis of rotation  110 . 
     The release device  100  comprises a support element  115 , which is embodied in one piece with the housing of the release device  100 , a first hydraulic actuator  120 , a second hydraulic actuator  125 , and a clutch support  130 . The support element  115  is preferably produced from a light-metal cast part. The support element  115  comprises several securing points  135 , with one of them being shown in greater detail in the area A in  FIG. 2 , an axial contact area  140 , and a radial contact area  145  in the area B, which is shown in greater detail in  FIG. 3 , and hydraulic connector elements  150  in the area C, which are shown in greater detail in  FIG. 4 . The securing points  135  are located, with regards to the axis of rotation  110 , at distances exceeding a radius of the clutch support  130  such that the release device  100  at the clutch bell  105  can be fastened when the clutch support  130  is already fastened at the support element  115 . 
     The hydraulic actuators  120  and  125  are arranged concentrically about the axis of rotation  110 . Each of the hydraulic actuators  120 ,  125  is embodied to apply a force, acting towards the left opposite the clutch bell  105  when a hydraulic pressure is generated in a corresponding hydraulic supply line. The force of each hydraulic actuator  120 ,  125  acts against a spring force of the corresponding lamellae clutch, which stressed the respective clutch in the axial direction and this way generates a force-fitting connection. When operating one of the actuators  120 ,  125  the spring load is released and/or the lamellae or friction disks are separated from each other in the axial direction so that the force-fitting connection is released. 
     The clutch support  130  is designed to form a counter-bearing for one or both of the lamellae clutches. For example, tension springs, which compress one of the lamellae clutches in the axial direction, may be connected at their right end to the clutch support  130 . The clutch support  130  is rotationally fastened via a roller bearing, preferably a separable ball bearing, at the support element  115 . 
       FIG. 2  shows a detail of the release device  100  of  FIG. 1  in the area A indicated there. The detail shown illustrates a fastening of the upper securing point  135  at the clutch bell  105 . 
     The securing point  135  is formed by a contact area  205  of an extension of the support element  115  and a recess  210  to accept a bolt (not shown) extending through the contact area  205 . The contact area  205  of the support element  115  is provided for contacting a contact area  215  of the clutch bell  105 . The support element  115  is shaped however such that it already contacts the clutch bell  105  in the axial direction in the proximity of the axis of rotation  110  before the contact areas  205  and  215  contact each other. Accordingly, initially a gap  220  forms between the contact areas  205  and  215 . By screwing the bolt through the recess  210  towards the right into the clutch bell  105  the contact areas  205  of the support elements  115  and  215  of the clutch bell  105  can approach each other in the axial direction, with the support element  115  being subjected to axial pre-stressing. 
       FIG. 3  shows another detail of the release device  110  of  FIG. 1  in the area B indicated there. The detail shows contact areas between the support element  115  and the clutch bell  105  in the proximity of the axis of rotation  110 . 
     The axial contact area  140  of the support element  115  contacts the clutch bell  105  at an axial contact area  305 . This contact prevents any further motion of the support element  115  towards the right, resulting in a gap  220  forming in  FIG. 2  as long as the support element  115  is free from tension, i.e. it is supported without any stress towards the right in the area of the securing point  135 . 
     The radial contact area  145  of the support element  115  contacts a radial contact area  310  of the clutch bell  105 . Here, the contact areas  145  and  310  are circumferential about the axis of rotation  110  so that the release device  100  is centered about the axis of rotation  110  with regards to the clutch bell  105 . 
       FIG. 4  shows another detail of the release device  100  of  FIG. 1  in the area C indicated there. The detail shows a hydraulic connector element  150  of the release device  100 . 
     The hydraulic adapter  150  is allocated to one of the hydraulic actuators  120 ,  125 . A first channel  405  extends within the support elements  115  in a direction parallel in reference to the axis of rotation  110 . Additional channels within the support element  115 , not shown in their entirety, connect the first channel  405  to a cylinder  410  of one of the actuators  120 ,  125 . The cylinders  410  are formed like rings and/or toruses about the axis of rotation  110 . Corresponding hollow-cylindrical pistons  415  are received in the cylinders,  410 , movable towards the left, and seal the cylinders  410  towards the left in a fluid-tight fashion. 
     A second channel  420 , extending within the clutch bell  105 , is aligned axially opposite the first channel  405 . Opposite ends of the channels  405  and  420  are each conically widened. Optionally an elastic seal (not shown) is provided, for example an O-ring, in an area inside the conical expansions and between ends of the channels  405  and  420  located opposite each other. This way a fluid-tight connection is established between the piston  410  of the respective actuator  120 ,  125  and the second channel  420  of the clutch bell  105 . The second channel  420  may particularly be connected to a hydraulic control device, which is implemented to select gears in a transmission connected to the clutches, which can be operated via the actuators  120 ,  125 . 
     When a fluid pressure in the second channel  420  is increased here a force develops, which tends to move the support element  115  towards the left away from the clutch bell  105 . By the pre-stressing of the support element  115  at the securing points  135  this force is supported in such a fashion that a seal is ensured in the area of the connector element  150 . 
       FIGS. 5A and 5B  show perspective views of the support element  115  of the release device  100  according to  FIGS. 1 to 4 . The left illustration in  FIG. 5A  shows a surface facing the clutch bell  105 , while the right illustration in  FIG. 5B  shows a side of the support element  115  facing away from the clutch bell. In a hub area around the axis of rotation  110  (not shown) annular recesses are formed in the support element  115  to form the cylinders  410  as well as the contact areas  140  and  145 . Radial projections  505  extend from the hub area to the securing points  135 . One of the projections  505  comprises the hydraulic connector elements  150 . The securing points  135  are not distributed evenly over the circumference, rather the angles are uneven between the neighboring securing points  135  with regards to the axis of rotation  110 . This way, a rotational assembly position of the support element  115  with regards to the axis of rotation  110  is defined at the clutch bell  105 . 
       FIGS. 6A and 6B  show perspective views of the support element  115  of the release device  100  in another embodiment. In  FIG. 6A  a side of the support element  115  is shown facing the clutch bell  105 , in  FIG. 6B  a side of the support element  115  facing away from the clutch bell  105 . Contrary to the illustration of  FIGS. 5A and 5B  the support element  115  shown in  FIGS. 6A and 6B  comprises two elements, which are connected to each other. The first element is a hydraulic connection element  605 , which is essentially equivalent to the support element  115  of  FIG. 5  without any projections  505 . Additionally, an alignment pin  610  is provided as well as bores  615  for accepting additional alignment pins, in order to define a rotationally unambiguous assembly position of the hydraulic connection element  605 . 
     The support element  115  shown in  FIGS. 6A and 6B  comprises as the second element a connection element  620 , which is connected to the connector element  605 , for example via a press fit. The connection element  620  is essentially disk-shaped and may comprise one or more circumferential beads or grooves in order to improve the axial spring features of the connection element  620 . For an improved illustration, in the left as well as the right area one section of the connection element  620  each is shown cut off. The securing points  135  are provided in a greater plurality than in the exemplary embodiment of  FIGS. 5A and 5B , and may be distributed evenly over a circumference around the axis of rotation  110  (not shown). 
     LIST OF REFERENCE CHARACTERS 
     
         
           100  Release device 
           105  Clutch bell 
           110  Axis of rotation 
           115  Support element 
           120  First hydraulic actuator 
           125  Second hydraulic actuator 
           130  Clutch support 
           135  Securing points 
           140  Axial contact area of the support element 
           145  Radial contact area of the support element 
           150  Hydraulic connection 
           205  Axial contact area of the support element 
           210  Recess 
           215  Axial contact area of the clutch bell 
           220  Gap 
           305  Axial contact area of the clutch bell 
           310  Radial contact area of the clutch bell 
           405  First channel 
           410  Cylinder 
           415  Piston 
           420  Second channel 
           505  Extension 
           605  Hydraulic connector element 
           610  Alignment pin 
           615  Bore 
           620  Connection element