Abstract:
A clutch assembly for a manual shift transmission includes a first shaft, which carries a first clutch disc, a second shaft that is coaxial to the first shaft. The second shaft carries an axially shiftable second clutch disc, a first ramp, of which at least one section describes a helical line that is coaxial to the shafts, and a first actuating body. The first actuating body is clamped between the first ramp and the second clutch disc and can be moved about a common axis of the shafts between an open position, in which the clutch discs are spaced from one another, and a closing position, in which the clutch discs contact one another in a frictionally joined manner.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to German Patent Application No. 102013021947.7 filed Dec. 20, 2013, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The technical field relates to a manual shift transmission and in particular a clutch assembly for such a manual shift transmission. 
     BACKGROUND 
     The clutches of conventional manual shift transmissions are typically designed for actuation by a clutch pedal and include two interacting clutch discs and a release bearing which annularly extends about a shaft of the clutch. The release bearing is axially moveable through pedal actuation, which axially adjusts one of the clutch discs via a release plate acting as a lever. Levers employed for actuating the release bearing require substantial installation space both in the direction of the axis as well as in radial direction. Apart from this, such a clutch is not well-suited for automatic actuation by means of an actuator, since rotary movement of the actuator initially has to be converted into a linear movement or alternately a step-down transmission between actuator and release bearing has to be provided in order to generate the force required for shifting the release bearing. 
     SUMMARY 
     In accordance with the present disclosure a clutch assembly is provided having a compact construction that is well suited for automated actuation. In particular, the present disclosure provides a clutch assembly with a first shaft carrying a first clutch disc, a second shaft carrying a second clutch disc that is coaxial to the first shaft and axially shiftable. A first ramp, of which at least one section describes a helical line is coaxial to the shafts and a first actuating body which, clamped between the first ramp and the second clutch disc, can be moved about a common axis of the shafts between an open position, in which the clutch discs are spaced from one another, and a closing position, in which the clutch discs touch one another in a frictionally joined manner. Accommodating the actuating body takes up minimal installation space and since an adjusting force can be exerted on the actuating body with a large lever arm, a simple and small actuator is sufficient for automated automation. 
     Between the actuating body and the second clutch disc a rolling bearing can be clamped in order to keep the force which upon rotation of the second shaft acts from the second clutch disc onto the actuating body in circumferential direction of the shaft. The smaller this force, the lower is the torque which an actuator has to be capable of generating in order to move the actuating body. In order to make possible a low-friction adjustment, the actuating body can in particular be formed as a ball. 
     According to a preferred configuration, the ramp apart from the helicoid section also includes a neutral section, on which the actuating body can be moved while the clutch discs are in the open position. Such a neutral section makes possible to utilize the same actuator for adjusting the clutch discs and for engaging a gear in a manual shift transmission in which the clutch assembly according to the present disclosure is used. 
     The neutral section can be surrounded on both sides by helicoid sections. Accordingly, each movement of the actuating body about the axis regardless of the direction, following the leaving of the neutral section and entry into one of the helicoid sections, ultimately leads to the reaching of the closing position. The advantages of this measure have an effect during the shifting of gears in a manual shift transmission using the clutch assembly. 
     According to a further development, the clutch assembly can be designed as a double clutch assembly, in which the first shaft carries a third clutch disc, a third shaft is designed as a hollow shaft concentrically surrounding the second shaft and carries an axially shiftable fourth clutch disc. A second actuating body, clamped between a second ramp and the fourth clutch disc, can be moved about a common axis of the shafts between an open position, in which the third and fourth clutch discs are spaced from one another, and a closing position, in which the third and fourth clutch discs touch one another in a frictionally joined manner. The first and second clutch disc can form a first clutch disc assembly and the third and fourth clutch disc a second disc assembly. 
     When the disc assemblies have different radii, they can be arranged overlapping one another in a space-saving manner. The first and second ramps can also be arranged on different radii with respect to the axis but in the process, for exerting the pressure that is necessary for establishing the frictional connection between the clutch discs have to be axially supported on a same carrier. 
     A lever, which acts on the actuating body arranged on the smaller radius, can extend through a gap that is kept clear between the carrier and the ramp arranged on the larger radius. In this way it can be prevented that the first and second actuating bodies mutually obstruct one another during their movements. 
     In order to evenly distribute the closing pressure on the second clutch disc over its circumference, at least three actuating bodies and first ramps should be distributed about the second shaft, namely preferentially on a circle that is coaxial to the axis and/or same angular intervals. Preferentially, the number of the actuating bodies and ramps in each case is exactly three. 
     The actuating bodies can be received in bores of a preferably disc-shaped holder that is rotatable about the second shaft. In particular when the actuating bodies are balls and are received in the bores with little play, they can, subject to an actuating force exerted on them by the disc in circumferential direction, rotate between ramp and rolling bearing, thereby making possible a low-friction adjustment. 
     In order to drive the adjustment, the holder can have a toothed segment. In particular when multiple actuating bodies and associated ramps are arranged on a same radius, the freedom of movement of an individual actuating body is practically only a fraction of a full circle in each case, and accordingly the toothed segment also has to extend at best over a fraction of a circle. 
     According to a further configuration of the present disclosure a manual shift transmission is provided with a clutch assembly as described above. The manual transmission also includes a gear shift sleeve, which can be moved between a neutral position, in which it allows the rotation of a loose wheel about a shaft, and a locking position, in which it locks the loose wheel on the shaft in a positively joined manner. A slotted link is provided having at least one section which describes a helical line with an axis that is parallel to the shaft, and a cam interacting with the slotted link, wherein of cams and slotted link the one, coupled to the rotation of the holder, is rotatable about the axis and the other drives the axial movement of the gear shift sleeve. Such a construction allows driving, with a single continuous actuating movement of an actuator, both the engaging and disengaging of a gear by shifting the gear shift sleeve, as well as adjusting the clutch disc between open and closing position. 
     When the helicoid section of the slotted link is surrounded on both sides by neutral sections extending about the shaft in circumferential direction it can be brought about that the adjustment of the clutch discs and the movement of the gear shift sleeve takes place in different phases of the actuating movement. In particular, the cam should interact for this with the helicoid section of the slotted link in particular when the actuating body is situated on the neutral section of the ramp. It can be thus ensured that the clutch discs are always in the open position while the gear shift sleeve is being moved so that no simultaneously transmitted torque can obstruct the adjustment of the gear shift sleeve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements. 
         FIG. 1  is a schematic section through a clutch assembly according to the present disclosure along the plane designated I-I in  FIGS. 2 and 3 ; 
         FIG. 2  is a top view of a carrier of the assembly from  FIG. 1 , with three ramps and balls guided on the ramps; 
         FIG. 3  is a section along the plane III-III from  FIG. 1 ; 
         FIG. 4  is an axial section through a manual shift transmission with a clutch assembly according to a further developed configuration of the present disclosure; 
         FIG. 5  is a top view of the carrier of the clutch assembly from  FIG. 4  with six ramps arranged on two concentric circles; 
         FIG. 6  is a section along the plane VI-VI from  FIG. 4 ; and 
         FIG. 7  is a section through a clutch assembly according to a version. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. 
       FIG. 1  shows a clutch assembly according to a first configuration of the present disclosure in a highly schematic form. On a first shaft  1  a first clutch disc  2  is attached in a rotationally fixed and axially immovable manner. A second shaft  3  is situated coaxially opposite to an end of the shaft  1 . The second shaft  3  carries a second clutch disc  4  in a rotationally fixed but axially moveable manner. The shaft  3  extends through an opening of a plate-shaped carrier  5 , which is connected in a fixed manner with a housing of a manual shift transmission (not shown) or forms a wall of this housing. In an aperture  7  of the carrier  5 , the shaft  3  is held and guided through rolling bearings  6 . 
     Coaxially to the shaft  1 , a disc-shaped holder  8  with multiple axial bores  9 , each of which receives an actuating body  10 , extends round about the aperture  7 . The actuating bodies  10  in this case are spherical; other shapes in use for the rolling bodies of rolling bearings, such as cylindrical or truncated cone shapes are likewise possible. The actuating bodies  10  each engage on a side in a ramp  11  recessed in the carrier  5 . The depth of the ramp  11  is variable round about the shaft  1  in circumferential direction; in the section plane shown in  FIG. 1 , the actuating bodies  10  are each located at a point of maximum depth of the ramps  11 . On a side which is located opposite the carrier  5  the actuating bodies  10  are in contact with an axial rolling bearing  12 . A spring which is not shown exerts a force in axial direction on the clutch disc  4 , through which the actuating bodies  10  and the rolling bearing  12  are held clamped between the clutch disc  4  and the carrier  5 . On an edge region of the disc-shaped holder  8 , a toothed segment  13  that is coaxial to the shaft  1  is formed. 
     When the clutch assembly is installed in a manual shift transmission, the toothed segment  13  meshes, as shown in  FIG. 1 , with a gear  14 . An at least sectionally helicoid slotted link  15  is formed for converting rotary movement into translation. In the case shown here the gear  14  is rotatable about an axis  16 , but held axially immovable on a shaft  16 ′ extending along the axis  16 , and a cam  17  projecting from the shaft  16 ′ engages in the slotted link  15  in order to convert a rotation of the gear  14  into an axial translation of the rotationally fixed shaft  16 ′. 
       FIG. 2  shows a top view of the carrier  5  and the three actuating bodies  10  engaging in the ramps  11  of the carrier  5 . The ramps  11  each have three sections following one another in circumferential direction, a central section  18  and pitch sections  19  adjoining the central section on both sides, in which the depth of the ramp  11  in each case decreases towards the outside. 
       FIG. 3  shows a section through the clutch assembly along the plane described III-III in  FIG. 1  and passing through the disc-shaped holder  8 . In  FIG. 2  and  FIG. 3  the actuating bodies  10  are each situated in a neutral position, in the middle of the central section  18  of their ramps  11 . When the holder  8  is driven to rotate about the shaft  3  via the gear  14 , the actuating bodies  10  move in circumferential direction over the ramps  11 . For as long as they are still situated in the central section  18 , their spacing from the clutch disc  2  does not change in the process. 
     However, since the cam  17  engages in a helicoid section  20  of the slotted link  15 , while the actuating bodies  10  are situated in the central section  18 , a translation of the shaft  16 ′ is achieved which can be utilized in order to for example actuate a gear shift sleeve of a locking synchronizer which is known per se and not shown in the figures on the shaft  3  or another shaft of the manual shift transmission, thereby engaging a gear in the manual shift transmission. 
     After the shaft  16 ′ has shifted the gear shift sleeve far enough in order to engage the gear the cam  17  reaches a neutral section  21  of the slotted link  15  oriented in circumferential direction of the axis  16  so that, when the gear  14  is rotated further, the shaft  16 ′ is no longer further displaced. As a consequence of this further rotation however the actuating bodies  10  enter pitch sections  19 , in which they are guided along a helical line that is coaxial to the shafts  1 ,  3  and, in the process, corresponding to the pitch of the helical line, advance against the clutch disc  2 . The pressure of the actuating bodies  10  is transmitted via the rolling bearing  12  to the clutch disc  4 , pressing the latter against the clutch disc  2 , so that the clutch closes and via the previously engaged gear, torque from the shaft  1  is transmitted to an output of the manual shift transmission. 
       FIG. 4  shows a further developed configuration of the clutch assembly and a manual shift transmission driven via the clutch assembly in an axial section. Again, a shaft on the drive side is designated  1 , a shaft on the output side  3 , clutch discs connected to the shaft  1 , here in the form of a disc assembly  2  and clutch discs connected to the shaft  3 ,  4 . A carrier, which connects the clutch discs  4  to the shaft  3  substantially has the shape of a flat bowl  23  with a wall section  24  oriented in axial direction, from which the clutch discs  4  radially project to the outside. Accordingly, a carrier of the clutch discs  2  is designed as a bowl  25  of a slightly larger diameter anchored on the shaft  1 , in which the clutch discs  2  or discs project from an axial wall section  26  to the inside in order to engage between the discs  4 . The wall section  26  is followed by a wall section  27  running radially inwardly, in which apertures  28  which are evenly distributed in circumferential direction are formed. Through the apertures  28  the clutch discs  4  are connected to the rolling bearing  12  and if appropriate exposed to the pressure exerted by the actuating bodies  10 . 
     A ring  29 , in which the ramps  11  guiding the actuating bodies  10  are recessed, is supported on the wall  5  of the transmission housing via multiple short columns  30  which are preferentially arranged directly behind the central section  18  of the ramps  11 . 
     Through a gap  31  kept clear between the ring  29  and the wall  5  an actuating lever  32  extends (see also  FIG. 6 ). On a free end of the actuating lever  32  a toothed segment  33  is formed, which like the toothed segment  13  of the holder  8  is provided in order to be driven by a gear  14 ′, which like the gear  14  described with respect to  FIG. 1  is provided with a slotted link  15 . The inner end of the actuating lever  32  is connected with a disc-shaped holder  34 , which is accommodated in a central aperture of the holder  8  and like the same has three bores in which spherical actuating bodies  35  are captive. The arrangement of the holders  8 ,  34  radially nested into one another is evident in particular in the sectional representation of  FIG. 6 . As is evident in particular in  FIG. 5 , the actuating bodies  35  are moveable in ramps  36  which are recessed on a circle with smaller diameter than those of the ramps  11  in the ring  29 . The sub-division of the ramps  36  into central section  18  of constant depth and pitch sections  19  is the same as in the ramps  11 . 
     As is evident in turn in  FIG. 4 , the actuating bodies  35 , via a second axial rolling bearing  37  surrounded by the rolling bearing  12  act on clutch discs  38 , which are anchored axially moveably on an end facing the shaft  1  of a hollow shaft  22  concentrically surrounding the shaft  3 . They interact with clutch discs  39 , which are arranged on a second axial wall section  40  of the bowl  23 , radially formed within the disc assemblies by the clutch discs  2 ,  4  and overlapping with these in axial direction. 
     The manual shift transmission shown in the left part of  FIG. 4  is an arbitrary example of a double clutch transmission with which the clutch assembly described in the right part of the same figure and described above and can interact. Other designs of double clutch transmissions are equally possible. 
     The shaft  3  and the hollow shaft  22  each carry two fixed wheels  41 ,  42  and  43 ,  44  respectively. Auxiliary shafts  45 ,  46  are provided with loose wheels  47 - 53  and locking synchronizing devices  54 - 57 . 
     A selection mechanism  58  which is not described in detail here optionally couples either the gear shift sleeve of the locking synchronizing device  56  or that of the locking synchronizing device  54  to the shaft  16  and via the latter to the holder  8 . A second selection mechanism  59  optionally couples the gear shift sleeve of the locking synchronizing device  55  or  57  to the holder  34 . In order to engage the first gear, synchronized in  FIG. 4  as “ 1 ” in the circle, the locking synchronizing device  56  has to couple the loose wheel  50  to the auxiliary shaft  46 . In the selection mechanism  58 , the locking synchronizing device  56  is selected for this purpose and an actuator  60  acting on the gear  14 ′ is activated in order to shift the shaft  16 ′ and with it the gear shift sleeve of the locking synchronizing device  56  to the left, to the loose wheel  50 . When the loose wheel  50  is coupled to the shaft  46  and the shifting of the shaft  16 ′ terminated, the actuator  60  continues to rotate as a result of which the actuating bodies  10  enter the pitch sections  19  of their ramps  11  pressing the clutch discs  2 ,  4  against one another. 
     Even while the clutch discs  2 ,  4  are still in contact, an actuator  61  can be activated in order to bring the locking synchronizing device  57  in engagement on the loose wheel  53  and rotate the holder  34 . For as long as the actuating bodies  35  in the process remain in the central sections of their ramps  36  no torque is transmitted via the wheels  44 ,  53 . Only when the actuating bodies  35  enter the pitch sections of their ramps and the actuating bodies  10  simultaneously return into the central sections does a load change on the wheels  44 ,  53  and thus the shifting into the second gear, symbolized by “ 2 ” in the circle occur. 
     For the third gear, the wheel  47  is coupled to the shaft  45 , for the fourth the wheel  48  to the shaft  45 , for the fifth the wheel  51  to the shaft  46  and for the sixth gear the wheel  52  to the shaft  46 . 
     Via a third auxiliary shaft which is not shown the wheel  49  drives a reverse gear. Alternatively, the wheel  49  can mesh with the loose wheel  53  on the auxiliary shaft  46 , so that for engaging the reverse gear the wheel  49  is fixed to the auxiliary shaft  45  through the locking synchronizing device  55 , while the locking synchronizing device  57  is out of engagement with the loose wheel  53 . According to a further alternative, the fixed wheel  44  can be coupled to the wheel  49  via a wheel of an auxiliary shaft which is not shown. 
     Since even-numbered forward gears are each driven by one of the two shafts  3 ,  22  and odd-numbered ones by the respective other shaft, shifting without interruption between two successive gears is possible in each case. 
       FIG. 7  shows a second clutch assembly for a double clutch transmission in an axial section analogous to  FIG. 4 . Components of the same function in this are marked here with the same reference numbers as in  FIG. 4-6  and are not described again. Here, the outer axial rolling bearing  12  is arranged about the disc assembly formed by the clutch discs  2 ,  4  and axially offset against the inner rolling bearing  37 . The ramps  11 ,  36  lie in different planes perpendicular to the shaft  2 ; in the case shown here the ramps  11  are situated on the ring  29 , the ramps  36  by contrast on the wall  5  of the transmission housing. The structure of the holder  34  can be simplified because of this since these, other than shown in  FIG. 4 , can be unitarily plate-shaped like the holder  8 , with a toothed segment  33  extending along its edge. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment is only an example, and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the present disclosure as set forth in the appended claims and their legal equivalents.