Abstract:
The invention relates to a dual clutch for a dual clutch transmission for transmitting a torque from a drive shaft to at least one drive shaft, which comprises a first clutch, a second clutch, and an electrical actuating device. The actuating device comprises a coupling slide, wherein a first slide of the coupling slide acts on the first clutch, and a second slide of the coupling slide acts on the second clutch, and the two slides are movable in such a way that by displacing the slides a recoupling process is controlled.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a dual clutch for a dual clutch transmission according to the preamble of claim  1 . 
       BACKGROUND 
       [0002]    Dual clutch transmissions for the actuation of motor vehicles, which comprise two sub-transmissions, which in each case have a main clutch, are known from the technical field. The aforementioned main clutches are actuated by means of hydraulic actuating elements. Aside from these, clutches are known, which are actuated by means of electrical actuators, as for example electric motors, and suitable kinematics assigned to said actuators. A clutch is in each case actuated by a motor with an assigned kinematics, which is appropriately designed, independently of the other one. 
         [0003]    With regard to clutches actuated by means of electric motors, the electric motors are constantly supplied with current not only for closing the clutches but also for keeping them closed. The result is that the electric motors have to be adequately sized and the power electronics have to meet the required demands. With regard to clutches, which are controlled by an electric motor, it must be ensured that each of the two clutches of the dual clutch transmission can in each case be completely closed by an electric motor independently of each other. For this purpose, each of the two available electric motors has to produce the maximum closing force, which requires adequately powerful and therefore expensive electric motors. If an error occurs, both of the clutches open, which in each case are driven by an electric motor, so that the drag torque of the internal combustion engine is no longer available and the engine brake is ineffective. Thus, on the one hand a blocking of the transmission is prevented; however, on the other hand, the engine brake is ineffective. 
         [0004]    The European patent EP 1 178 234 B1 refers to a clutch arrangement. The clutch arrangement serves to transmit a torque from the drive shaft to an output shaft with a first coupling element and a second coupling element. The first coupling element is connected to the drive shaft and the second coupling element to the output shaft. Provision is made for an actuator, which specifies a nominal value for a torque to be transmitted with the clutch, as well as for an adjusting device, which uses the rotational power of the drive shaft for engaging and/or disengaging the coupling elements. The engaging and/or disengaging of the coupling elements results via a bevel toothed gear. The adjusting device is directly connected to the drive shaft and uses its rotational power squarely for positioning the coupling elements. In so doing, the actuating energy for the adjusting device, which is required for actuating the clutch arrangement, can be directly drawn from the drive train, respectively the drive shaft. The energy drawn from the drive train for an actuation of the clutch arrangement via the adjusting device is not initially used for driving an electric motor, an electric magnet or a hydraulic cylinder. On the contrary, the energy of the drive train is directly supplied without conversion to the adjusting device in order to actuate the clutch arrangement. 
       SUMMARY 
       [0005]    A dual clutch configured according to the invention for a dual clutch transmission for transmitting a torque from a drive shaft to at least one output shaft comprises a first clutch, a second clutch as well as an electrical actuating device. The actuating device comprises a coupling slide, wherein a first slide of the coupling slide acts on the first clutch, and a second slide of the coupling slide acts on the second clutch, and the two slides are movable in such a way that by displacing the slides a recoupling process is controlled. 
         [0006]    When employing a self-locking actuator, it is an advantage of the dual clutch according to the invention, that the current supply to the actuators, as a function of the design of the actuators, is only required when shifting as well as in individual operating states of the motor vehicle, i.e. if the motor vehicle is operated under full load. For this purpose, the two slides can preferably be jointly displaced with a first electrical actuator. A recoupling process is thereby controlled by a single actuator. A clutch is in each case closed in the end positions of the electrical actuator and the other one is open. If then the actuator is actuated, a recoupling is made from one clutch to the other one. 
         [0007]    In a preferred embodiment, the two slides can be displaced towards one another with a second electrical actuator. The recoupling process is corrected by the second electrical actuator. This can, for example, be necessary for reasons of driving comfort. 
         [0008]    In an embodiment, the first actuator comprises a spindle, which moves the entire coupling slide by rotation. If a force is now exerted on a slide by the clutch, this force can simultaneously be used to move the other slide. It is hereby possible to use a force transmitted from the opening clutch to the corresponding coupling slide in order to close the second clutch. As a result of this, the required output of the electrical actuator is reduced when implementing a recoupling process. 
         [0009]    The first electrical actuator, with which the entire coupling slide can be displaced, preferably comprises a threaded spindle, a chain drive, a gear drive or a rack and pinion drive. Any other arbitrary additional drive is also suitable, with which the entire coupling slide can be moved. 
         [0010]    In order that the slides of the coupling slide can be moved in opposite directions, the spindle, with which the slides are driven with the second actuator, preferably comprises a left-handed thread and a right-handed thread. The one slide is moved with the left-handed thread and the other with the right-handed thread. It is also alternatively possible for the second actuator for moving the slides to comprise acme screw thread, ball screws, worm gears or other arbitrary gears, which are known to the specialist. Thus, it is, for example, also possible for the spindle to be mounted in a slide and to have a thread, whereupon the other slide is moved. 
         [0011]    According to the invention, ramps are configured in each case on the slides, whereby the clutches are actuated. Spring levers, with which a clutch is opened or closed, are activated via the ramps. The progression of the recoupling process is specified by the form of the ramps on the slides. It is then, for example, possible for the ramps to have a constant gradient. The gradient of the ramps is, however, preferably configured in the form of a root function. The advantage of the configuration of the ramps with a profile with a root function is that a larger gradient can as a result be assigned to the smaller spring tension of a clutch and a smaller gradient to the greater spring tension. In this way, the displacement forces cancel each other out. 
         [0012]    Besides the form of a root function, the gradient can also assume any additional form. The gradient can preferably be described by a mathematical function. A gradient in the form of a logarithmic function, a parabola or a hyperbola is, for example, also possible. 
         [0013]    The gradients of the ramps are preferably adapted in such a way that the coupling slide is brought into a stable position when a breakdown in the tension occurs. Moreover, it is possible to exert a pre-load by means of a spring element, so that the slide can be drawn into a stable position if a breakdown in the tension occurs. 
         [0014]    In order that the coupling slide can be moved into a neutral position, i.e. a position, in which both clutches are open, it is necessary for provision to be made for non-self-locking drives for the absolute displacement of the entire coupling slide. Non-self-locking drives, however, require that a force is transmitted to the coupling slide to provide the torque transmission. 
         [0015]    If the first actuator, which moves the entire coupling slide, is implemented without self-locking, both of the slides (assuming an appropriately configured gradient of the ramp) in the event of a breakdown in the tension are displaced in such a way, that one clutch is closed and the other is open. The gradient of the ramp has to thereby be configured in such a manner that the reset force of the clutch, which is opening, is greater than the closing force, which is required for the closing of the other clutch. This can be guaranteed in an additional embodiment by means of an appropriate mechanism, with which the slide is pushed into a defined secure position. By virtue of the fact that when a breakdown in tension occurs, the slide is displaced in such a manner that one clutch is closed and the other is open, the engine brake is also available when a breakdown in tension occurs. Furthermore, locking of the transmission, as it would occur if both clutches are closed, is prevented. 
         [0016]    Spring elements are preferably used for opening and closing the clutches, each spring element acting with one side via an axial bearing and if need be a pressure sleeve against a ramp and with the other side against a pressure plate. Spring levers or disc springs, for example, are suitable as spring elements. The respective clutch disk is pressed with the pressure plate against a clutch block, which is driven by the internal combustion engine. One of the pressure sleeves is preferably guided in the other pressure sleeve, the pressure sleeves being able to be displaced in the axial direction to each other. 
         [0017]    The spring force on the spring element of the clutch, which is opening, preferably supports the movement of the spring element of the clutch, which is closing. The advantage of which is that at least one of the actuators with the associated power electronics can have a smaller size and thus be more cost effective. 
         [0018]    Both clutches are open only when stopping and during driveaway of the motor vehicle. When shifting the dual clutch transmission, one clutch is opened as a rule while the other one is closed at the same time. 
         [0019]    It is the advantage of the dual clutch embodied according to the invention that the electrical actuator, which controls the recoupling process, has to produce a smaller amount of power output. In so doing, the expenses for the electrical actuator and the necessary power electronics are reduced. Furthermore, the necessity of continually supplying the electric motors with current is eliminated as a function of the design of the gradients of the first ramp, respectively the second ramp. For this purpose, the ramps are designed in such a manner, that in the event that the first actuator, respectively the second actuator, is not supplied with current, the slides are positioned to each other in such a manner that one clutch is open and the other is closed. This has the further advantage that in the event of a system breakdown, the engine brake remains intact. An emergency operation function is possible when the actuators fail. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    Examples of embodiment of the invention are depicted in the drawings and are explained in detail in the following description. 
           [0021]    The following are shown: 
           [0022]      FIG. 1  is a schematic depiction of a dual clutch designed according to the invention, 
           [0023]      FIG. 2  is a schematic depiction of a coupling slide from a top view, 
           [0024]      FIG. 3  is a sectional view of a coupling slide designed according to the invention in a first embodiment, 
           [0025]      FIG. 4  is a sectional view of a coupling slide designed according to the invention in a second embodiment, 
           [0026]      FIG. 5  is a relative displacement of the two slides of the coupling slide, 
           [0027]      FIG. 6  is the displacement of the entire coupling slide, 
           [0028]      FIG. 7  is the displacement path of a coupling slide with ramps in the form of a root function. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]      FIG. 1  shows a dual clutch for a dual clutch transmission designed according to the invention. 
         [0030]    A double clutch transmission  1 , comprising two sub-transmissions with a clutch being assigned to each one, transmits the torque produced in an internal combustion engine, which is not depicted here, to a drive shaft  3  of the first sub-transmission, respectively a drive shaft  5  of the second sub-transmission, which encloses said drive shaft  3 . The internal combustion engine of concern is as a rule an internal combustion engine with a plurality of cylinders, for example a self-igniting internal combustion engine or one with an externally-supplied ignition. A rotational movement is transmitted by the internal combustion engine to a clutch block  7  of the dual clutch  1 . The dual clutch  1  is enclosed by a housing  9 . 
         [0031]    A first clutch  11  and a second clutch  13  of the dual clutch  1  are mounted within the housing  9 . The first clutch  11  is arranged on the inside, while the second clutch  13  is arranged on the outside. Both clutches  11 ,  13  of the dual clutch  1  are mounted concentrically with respect to each other within the housing  9 . Besides the clutches  11 ,  13 , which are depicted here equally sized, the clutches  11 ,  13  can also be configured in different sizes. 
         [0032]    The clutches  11 ,  13  can, for example, be configured as dry clutches or as wet clutches. Suitable clutches  11 ,  13  are, for example, single disk clutches, multiple disk clutches or multi-plate clutches. 
         [0033]    A first spring element  15  configured as a spring lever is assigned to the first clutch  11 , while the second clutch  13  is impinged upon by a second spring element  17 , which is configured as a spring lever. Disc springs can also, for example, be used as the spring elements instead of the spring levers  15 ,  17 . In order to close the first clutch  11 , the first spring element  15  exerts a compressive force on the first pressure disk  19 , which is pressed against a clutch disk  21  of the first clutch  11 . With the aid of the pressure disk  19 , the clutch disk  21  is then placed against a face  23 , which is configured on the clutch block  7 . In this way, the rotational movement of the clutch block  7  is transmitted to the clutch disk  21 . In order that the clutch disk  21  can be placed against the face  23 , the clutch disk  21  is mounted on the drive shaft  5  of the second sub-transmission in an axially displaceable manner. In the embodiment depicted in  FIG. 1 , the clutch disk  21  is guided in axially aligned grooves  25  for this purpose. The first pressure disk  19  is guided with guide pins  27 . The guide pins  27  are connected to the clutch block  7 . That means that the first pressure disk  19  and also the first spring element  15  rotate at the same speed, at which the clutch block  7  also rotates. 
         [0034]    In order to close the second clutch  13 , a spring tension of the second spring element  17  acts on a pin  29 , which is connected to the second pressure disk  31 . The second pressure disk  31  is pressed against a clutch disk  33  of the second clutch  13  in this manner and thus presses the clutch disk  33  against the clutch block  7 . The second clutch disk  33  is also mounted in an axially displaceable manner. For this reason, grooves  35  are configured in the drive shaft  3  of the first sub-transmission; and in so doing, the clutch disk  33  can be displaced in said grooves  35 . In the embodiment depicted in  FIG. 1 , the torque of the clutch block  7  is transmitted in this manner to the drive shaft  5  of the second sub-transmission by the first clutch  11  when said clutch  11  is closed. When the second clutch  13  is closed, the torque of the clutch block  7  is transmitted to the drive shaft  3  of the first sub-transmission. 
         [0035]    In order that a spring tension of the spring elements  15 ,  17  can be transmitted to the pressure disks  19 ,  31 , the first spring element  15  is mounted with one side at a first pivotal point  37  on the clutch block  7  and with the other side at a first compression bearing  39 . The second spring element  17  is correspondingly mounted at a second pivotal point  41  on the clutch block  7  and with the other side at a second compression bearing  43 . In order to achieve an even force distribution on the clutch disks  21 ,  33 , a plurality of spring elements  15 ,  17  is preferably assigned to each clutch disk. 
         [0036]    According to the embodiment depicted in  FIG. 1 , the first compression bearing  39  is placed against a first pressure sleeve  45  and the second compression bearing  43  against a second pressure sleeve  47 . The compression bearings  39 ,  41  are in each case configured as axial bearings because the spring elements  15 ,  17  move at the rotational speed of the clutch block  7 , whereas the pressure sleeves  45 ,  47  are stationary and do not execute rotational movement. 
         [0037]    Instead of the pressure sleeves  45 ,  47 , it is also possible to use throw-out bearings, which are linked with the clutch housing via levers. The throw-out bearings can move in the axial direction with respect to the dual clutch. A radial movement or movement in the circumferential direction is prevented by the lever. Installation space can be saved by the throw-out bearings vis-à-vis the use of pressure sleeves  45 ,  47 . 
         [0038]    In order to close the first clutch  11 , the first pressure sleeve  45  moves in the direction of the clutch blocks  7 . Through this action, the compression bearing  45  located at the first pressure sleeve  45  is axially moved in this direction and consequently exerts a force on the first spring element  15 . The first spring element  15  pushes on the pressure disk  19  and consequently places said disk  19  against the face  23  on the clutch block  7 . When the second clutch  13  is to be closed, the second pressure sleeve  47  is correspondingly moved in the direction of the clutch block  7 . This leads to a movement of the second compression bearing  43  likewise in the direction of the clutch block  7 , whereby a force acts on the second spring element  17 . The second spring element  17  pushes against the guide pin  29 , which is connected to the second pressure disk  31 , and thus presses the second pressure disk  31  against the clutch disk  33  of the second clutch  13 . The clutch disk  33  of the second clutch  13  is therefore placed against the clutch block  7 . In order to achieve a stable guidance of the second pressure disk  31 , it is possible that said disk  31  likewise is guided via the guide pin  27 . 
         [0039]    A radial movement of the first pressure sleeve  45  and the second pressure sleeve  47  is thereby avoided, in that the pressure sleeves  45 ,  47  are fit into each other. For this purpose, at least one groove  49  is configured on the first pressure sleeve  45 , wherein the second pressure sleeve  47  is integrated and is axially displaceable. A rotational movement of the first pressure sleeve  45  is thereby avoided, so that said sleeve  45  is guided in a stationary shaft  51 . For this reason, at least one groove  53  running in the axial direction, wherein the first pressure sleeve  45  is guided, is likewise preferably configured in the stationary shaft  51 . 
         [0040]    In order to be able to displace the first pressure sleeve  45  and the second pressure sleeve  47  in the axial direction, the dual clutch  1  configured according to the invention comprises a coupling slide  55 . The coupling slide  55  comprises a first slide  57 , whereupon a first ramp  59  is configured, and a second slide  61 , which is furnished with a second ramp  63 . 
         [0041]    In order to be able then to move the first pressure sleeve  45  and the second pressure sleeve  47  in the axial direction, a first appendage  65  is configured on the first pressure sleeve  45 . Said appendage  65  is placed against the first ramp  59 . A second appendage  67 , which is placed against the second ramp  63 , is configured on the second pressure sleeve  47 . In order to minimize wear, a roller  69  is configured in each case on the appendages  65 ,  67 , which runs on the first ramp  59 , respectively second ramp  63 . The first pressure sleeve  45 , respectively the second pressure sleeve  47 , runs along the first ramp  59 , respectively the second ramp  63 , by means of a movement in the radial direction of the first slide  57 , respectively the second slide  61 . As a result of this, the movement of the slides  57 ,  61  carried out in the radial direction is transformed into an axial movement of the pressure sleeves  45 ,  47 . 
         [0042]    In order that a clutch  11 ,  13  opens in each case while the other clutch  11 ,  13  closes at the same time, the gradients of the ramps  59 ,  63  are implemented in opposite directions. If the slides  57 ,  61  are displaced in the same direction, one of the two pressure sleeves  45 ,  57  is then moved in the direction of the clutch block  7 , while the second of two pressure sleeves  45 ,  47  is moved away from the clutch block  7 . One of the two clutches  11 ,  13  closes, while the other of the two clutches  11 ,  13  is opened. 
         [0043]    Provision is made for a first actuator  71  for recoupling by means of parallel displacement of the slides  57 ,  61 . The entire coupling slide  55  can be moved in the radial direction by the first actuator  71 . 
         [0044]    A compressive force acts on the compression bearing  39 ,  43  and thereby on the pressure sleeve  45 ,  47  via the spring element  15 ,  17  of the closed clutch  11 ,  13 . The opening movement of the clutch  11 ,  13  is supported by this compressive force. At the same time, the compressive force eases the movement of the slide  57 ,  61 . The first actuator  71  can consequently be scaled smaller. 
         [0045]    In order if necessary to be able to correct the recoupling process, provision is made for a second actuator  79 , with which the slides  57 ,  61  can be moved in opposite directions. 
         [0046]    An even movement of the slides  57 ,  61  is thereby achieved, in that they are activated by a common actuator  79 . A movement of the slides  57 ,  61  in opposite directions is thereby achieved, in that the second actuator  79  comprises a spindle  73 , whereupon a right-handed thread  75  and a left-handed thread  77  are configured. The first slide  57  thereby runs on the right-handed thread  75  and the second slide  61  on the left-handed thread  77 . It is also, of course, alternatively possible for the first slide  57  to run on the left-handed thread and the second slide  61  on the right-handed thread  55 . When the spindle  73  is in rotary motion, the first slide  57  moves in a certain direction while the second slide  61  is moved in the opposite direction. Instead of the first spindle  73  having left-handed and right-handed thread, the spindle can, for example, alternatively comprise acme screw thread, ball screws, cable controls or worm gears. The spindle  73  can also be mounted in one of the slides  57 ,  61  and have a thread, whereupon the other slide  57 ,  61  is moved. 
         [0047]      FIG. 2  shows a coupling slide  55  configured according to the invention from a top view. 
         [0048]    The coupling slide  55  configured according to the invention comprises the first slide  57  and the second slide  61 . The slides are in each case ovally configured in the embodiment, which is depicted here, so that each slide has two ramps  59 , respectively  63 . The two ramps prevent the pressure sleeves  43 ,  45  from canting. Besides the oval shape depicted here, the slides  57 ,  61  can, of course, assume any additional shape known to the specialist, wherein in each case at least two ramps  59 ,  63  can be configured side by side on one of the slides  57 ,  61 , whereby a canting of the pressure sleeves  45 ,  47  is avoided during movement. In the top view depicted here, the first actuator  71 , with which the slides  57 ,  61  can together be displaced parallel to each other, is arranged across from the second actuator  79 . In order that a movement of the entire coupling slide  55  is possible with the first actuator  71 , without hindering the displacement of the slides  57 ,  61  in the opposite direction, a bore-hole  81  is configured in the second slide  61 , through which a spindle  83  is guided, which is connected to the first actuator  71 . By rotating the second spindle  83 , the entire coupling glide  55  together with the second actuator  79  is moved. Instead of the spindle  83 , it is also possible to make provision for any other arbitrary drive mechanism, which is known to the specialist, whereby a radial displacement of the entire coupling slide  55  is possible. Such drives are, for example, chain drives, gear wheels, gear racks etc. 
         [0049]      FIG. 3  shows a sectional view of a coupling slide  55  configured according to the invention as per  FIG. 2 . 
         [0050]      FIG. 3  makes apparent how the first ramp  59  and the second ramp  63 , which are integrated onto the slides  57 , respectively  61 , are configured. In contrast to the embodiment depicted in  FIG. 1 , wherein the gradient of the slides  59 , respectively  63 , runs linearly, the ramps  59  and  63  in the embodiment depicted in  FIG. 3  have a gradient in the form of a root function. The advantage of this form is that a larger gradient is assigned to the smaller spring tension of the spring element  15 , respectively  17 , which acts on the ramp  59 , respectively  63 , when the clutch is open; and a smaller gradient is assigned to the greater clutch spring tension of the spring elements  15 ,  17  when the clutch is closed. In this way, the displacement forces cancel each other out. As a result of the action of the first actuator  71 , only just a very small force thus needs to be applied to displace the slides  57 ,  61 . 
         [0051]      FIG. 4  shows a coupling slide  55  configured according to the invention in a second embodiment. 
         [0052]    According to the embodiment depicted in  FIG. 4 , the first actuator  71 , with which the entire coupling slide  55  together with the second actuator  79  is moved, is not arranged across from the second actuator  79 , but parallel to it. 
         [0053]    Because of this arrangement, an appendage  85  is configured on the first slide  57 . A bore-hole  87  configured in said appendage  85  has inside thread, wherein the second spindle  83  is guided. 
         [0054]    In  FIG. 5 , the relative displacement of the two slides  57 ,  59  of the coupling slide  55  is depicted. In so doing, the radial movement of the slides  57 ,  59  is depicted on the x-axis  89 , and the gradient of the ramps  59  and  63  is depicted on the y-axis  91 . The position of the slides  57 ,  59  at a first point in time is depicted with a solid line. The two slides  57 ,  59  are now displaced towards each other by the second actuator  79 . 
         [0055]    As a result of this, the first slide  57  moves in the one direction as depicted by the arrow  93 , while the second slide  61  moves in the opposite direction as depicted with arrow  95 . The positions of the slides  57 ,  61  at a second point in time are depicted with a dot and dash line. The form of the ramps  59 ,  63  in the embodiment depicted in  FIG. 5  is linearly rising. 
         [0056]    In  FIG. 6 , a displacement of the entire coupling slide  55  is depicted, whereby a recoupling process results. The slides  57 ,  61  are initially situated in a starting position, whereat one of the two clutches  11 ,  13  is open and the other is closed. The entire coupling slide  55  is displaced when the first actuator  71  is actuated. The arrow denoted with the reference numeral  97  shows this action. Also in the embodiment depicted in  FIG. 6 , the movement of the slide  57 ,  61  is depicted on the x-axis, while the gradient of the ramps  59 ,  63  is depicted on the y-axis. In so doing, the starting position of the coupling slide  55  is depicted with a solid line, and the position of the coupling slide  55  after the displacement is depicted with a dot and dash line. As is apparent in  FIG. 6 , the position of the ramps  59 ,  63  does not change with respect to each other when a displacement of the entire coupling slide  55  takes place. In the second position, the clutch  11 ,  13  is now closed, which initially was open, and the other one is now open. 
         [0057]    In  FIG. 7 , the distance, which was covered by the pressure sleeves  45 ,  47 , is depicted as a function of the angle of rotation of the first actuator  71 . The angle of rotation of the first actuator  71  is thereby plotted on the x-axis  89  and the distance covered by the pressure sleeves  45 ,  47  on the y-axis  91 . The first spindle  73  is set into rotation by the rotational movement of the first actuator  71 . The first slide  57  and the second slide  61  are displaced parallel to each other with increasing rotation of the spindle  73 . At the beginning, the first clutch  11  is open and the second clutch  13  is closed. The distance covered by the first pressure sleeve  45 , with which the first clutch  11  is opened and closed, is denoted with the reference numeral  99 . The distance covered by the second pressure sleeve  47 , with which the second clutch  13  is opened or closed, is denoted with the reference numeral  101 . The first slide  57  and the second slide  61  are displaced parallel to each other by the rotational movement of the first actuator  71 . This leads to a movement of the first pressure sleeve  45 , respectively the second pressure sleeve  47 , due to the ramps  59 ,  63 , which are configured on the first slide  57  and the second slide  61 . On account of the movement, the second clutch  13 , which is closed at the beginning, is opened, while the first clutch  11 , which is open at the beginning, is closed. The distance covered by the pressure sleeves  43 ,  45  is thereby dependant on the gradient of the ramps  59 ,  63 . In order to cover a distance, as it is depicted in  FIG. 7 , the ramps  59 ,  63  are configured with a gradient in the form of a root function. Besides the gradient in the form of a root function, the ramp can also assume any other gradient, which can be depicted by a mathematical function. It is therefore, for example, also possible for the gradient to be configured in the form of a logarithmic function, a hyperbola or a parabola. This leads to the fact, that the clutch, which is being closed, initially covers a large distance with little movement of the first actuator  71 ; and as the closing activity of the clutch increases, the distance, which is covered as a result of the movement of the actuator  71 , becomes smaller. Correspondingly with regard to the clutch, which is being opened, a smaller distance is initially covered; and the wider the clutch is opened, the greater is the distance, which is covered by the clutch at the same amount of travel by the actuator  71 . When the second actuator  79  is actuated, the slides  57 ,  59  are moved in opposite directions. Such a displacement is exemplary depicted for the first pressure sleeve  45 . The displacement path is denoted with the arrow  103 . The curve of the actuation displacement of the first pressure sleeve  45  is denoted with the reference numeral  105 .