Abstract:
A torque transmitting unit in the power train of a motor vehicle for transmitting torque between a drive unit having an output shaft and a transmission having at least one input shaft. A clutch is positioned between the transmission input shaft and the drive unit output shaft. The clutch includes an input part that has a clutch cover that defines a clutch-containing volume and that is supported by a transmission housing section. In order to limit axial vibrations of the clutch, the clutch input part is axially supported by a bearing.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a torque transmitting unit in the power train of a motor vehicle for transferring torque between a drive unit, in particular a combustion engine, having an output shaft, in particular a crankshaft, and a transmission having at least one input shaft, there being inserted between the transmission input shaft and the output shaft of the combustion engine a clutch device having at least one input part, which has a clutch housing section, in particular a clutch cover, which limits the volume accommodating the clutch device and is supported by a transmission housing section. 
     The object of the invention is to create a simply constructed and economically manufacturable torque transmitting unit with which fewer vibrations occur in the coupling device in the axial direction than with conventional torque transmitting units. 
     SUMMARY OF THE INVENTION 
     The object is achieved with a torque transmitting unit in the power train of a motor vehicle for transferring torque between a drive unit, in particular a combustion engine, having an output shaft, in particular a crankshaft, and a transmission having at least one input shaft, there being inserted between the transmission input shaft and the output shaft of the drive unit a clutch device having at least one input part which has a clutch housing section, in particular a clutch cover, which limits the volume accommodating the clutch device and is supported by a transmission housing section, in that the input part of the clutch device is borne or supported in the axial direction on the clutch housing section with the help of a bearing device. Due to the bearing of the clutch input part according to the invention, bearing devices between the input part of the clutch device and the transmission input shaft or the output shaft of the drive unit may be dispensed with. 
     A preferred exemplary embodiment of the torque transmitting unit is characterized in that the clutch device includes a wet operating clutch arrangement, in particular a multiple-disk clutch arrangement, which is operable by means of an operating lever which is connected to the input part of the clutch device in a rotationally fixed connection. Lever-operated wet clutches have the disadvantage that the operating forces which are brought in from outside through an appropriate actuating system have to be braced. It is possible to support the clutch input part in the axial direction on the crankshaft of the combustion engine. The bearing or supporting of the clutch input part in the radial direction can be accomplished for example by a needle bearing or journal bearing which is supported in the radial direction on the transmission input shaft. In conjunction with the present invention it was determined that when the clutch input part is supported in the axial direction on the crankshaft, bending vibrations which develop due to gas cycle forces of the combustion engine are transferred directly to the wet clutch arrangement in the form of axial vibration. Since the engagers are supported on the transmission housing in lever-operated wet clutches, these vibrations are transmitted to the operating lever and can falsify the counterpressure force. The torque transmitting unit according to the present invention enables a cost-effective solution to be produced, which makes both radial and axial support of the wet clutch and a vibration-free support point possible. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that an axial bearing device is positioned between the input part of the clutch device and the clutch housing section. The axial bearing device may be for example an axial roller bearing or an axial needle bearing. An axial journal bearing may also be provided, however. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that a radial bearing device is positioned between the input part of the clutch device and the clutch housing section or between the input part of the clutch device and the at least one transmission input shaft. The radial bearing device may be supported directly on one of the transmission input shafts, or through hubs on one of the transmission input shafts. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that an axial bearing device, preferably an axial roller bearing, is positioned radially outside of one end of the clutch housing section, in particular a clutch cover. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that the radial bearing device is positioned radially inside a radial shaft seal ring. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that the radial bearing device is positioned axially overlapping the radial shaft seal ring. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that the radial bearing device is positioned in the radial direction between a leg of the clutch input part and a hub part. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that the radial bearing device and the axial bearing device are made of a single part or of a plurality of parts. The radial bearing device and the axial bearing device may be formed for example as journal bearings or as needle bearings. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that the bearing device, for example a thin ring ball bearing device, is designed and positioned between the clutch housing section and the input part of the clutch device in such a way that the input part of the clutch device is supported in both the radial and the axial directions on the clutch housing section. The thin ring ball bearing is preferred because of the low friction losses. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that the bearing device has a contact normal which is tilted from the radial direction. That makes support in both the radial and the axial directions possible in a simple way. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that a journal bearing device is positioned between the clutch housing section and the input part of the clutch device. The journal bearing device may be effective in both the radial and the axial directions, i.e., it may for example be provided with an axial thrust face. The axial and radial support functions of the journal bearing may also be separate, however. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that a seal device, for example a radial shaft seal ring, is positioned between the input part of the clutch device and the clutch housing section. The seal device seals the interior of the clutch device toward the outside. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that the bearing device is positioned coaxial to and radially outside of the seal device. That creates an easily realized possibility for positioning the bearing device in the interior of the clutch device, which is sealed toward the outside by the seal device. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that the bearing device is positioned overlapping the seal device in the axial direction. That makes it possible to save construction space in the axial direction. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that the bearing device is positioned in a wet chamber which is bounded by the clutch housing section. That makes it possible to supply the bearing device with lubricant from the wet chamber of the clutch device in a simple way. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that two wet operating clutch arrangements are positioned coaxially and overlapping each other in the axial direction. That makes it possible to save construction space in the axial direction. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that a vibration damping unit is inserted between the output shaft of the drive unit and the clutch device. The vibration coupling device serves to reduce unwanted transfer of vibrations from the drive unit to the transmission. 
     Another preferred exemplary embodiment of the torque transmitting unit is characterized in that the clutch housing section is formed in a single piece with the transmission housing section. That makes it possible to reduce the number of individual parts. 
     In a power train of a motor vehicle, the object indicated above is solved by a torque transmitting unit described earlier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Additional advantages, characteristics, and details of the present invention are evident from the following description, in which various embodiments are described in detail with reference to the drawings. The characteristics mentioned in the claims and in the description may be essential to the invention individually by themselves or in any combination. The figures show the following: 
         FIG. 1  shows a half-sectional view of a torque transmitting unit according to the present invention, having a thin ring ball bearing; 
         FIG. 2  shows a depiction similar to that in  FIG. 1  according to a second exemplary embodiment having two roller bearings, and 
         FIG. 3  shows a depiction similar to that in  FIG. 1  according to a third exemplary embodiment having a journal bearing. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Part of a power train  1  of a motor vehicle is illustrated in  FIG. 1 . Positioned between a drive unit  3 , in particular a combustion engine, from which a crankshaft  4  extends, and a transmission  5 , is a wet operating double clutch  6  of multiple-disk design. Connected between drive unit  3  and double clutch  6  is a vibration damping unit  8 . The vibration damping unit is preferably a two-mass flywheel. 
     Crankshaft  4  of combustion engine  3  is rigidly connected through a screw connection  9  to an input part  10  of vibration damping unit  8 . Input part  10  of vibration damping unit has essentially the form of a circular ring extending in the radial direction, to which a starter gear rim  11  is welded radially on the outside. In addition, a centrifugal mass  12  is welded onto the input part  10  of vibration damping unit  8 . Furthermore, attached to input part  10  of vibration damping unit  8  is a vibration damper cage  14 , which at least partially incorporates a plurality of energy storage devices, in particular spring devices  16 . An output part  18  of vibration damping unit  8  engages spring devices  16 . Another centrifugal mass  19  is attached to output part  18  of vibration damping unit  8 . Output part  18  of vibration damping unit  8  is rigidly connected through a connecting part  21  to an input part  24  of double clutch  6 . Clutch input part  24  is joined in one piece to an outer disk carrier  26  of a first multiple-disk clutch arrangement  27 . Positioned radially inside outer disk carrier  26  is an inner disk carrier  28  of first multiple-disk clutch arrangement  27 . Inner disk carrier  28  is attached radially inside to a hub piece  30 , which is connected through toothing to a first transmission input shaft  31  in a rotationally fixed connection. 
     Clutch input part  24 , or outer disk carrier  26  of first multiple-disk clutch arrangement  27 , which is connected to the latter in a single piece, is connected through a connecting part  34  to an outer disk carrier  36  of a second multiple-disk clutch arrangement  38  in a rotationally fixed connection. Positioned radially inside outer disk carrier  36  is an inner disk carrier  40  of second multiple-disk clutch arrangement  38 , which is rigidly connected radially on the inside to a hub part  41 . Hub part  41  is connected through toothing in a rotationally fixed connection to a second transmission input shaft  42 , which is designed as a hollow shaft. First transmission input shaft  31  is positioned in second transmission input shaft  42  so that it can rotate. 
     The two multiple-disk clutch arrangements  27  and  38  are operated by means of operating levers  44  and  45 , whose radially inner ends are supported on operating bearings  48 ,  49 . Operating bearings  48 ,  49  are operated in the axial direction with the help of operating pistons  51 ,  52 . Operating pistons  51 ,  52  are arranged in fixed positions with respect to operating levers  44 ,  45 , which pivot with clutch input part  24 . 
     Positioned between connecting part  21  and outer disk carrier  26  of first multiple-clutch arrangement  27  is a clutch cover  55 , which is attached radially on the outside to a transmission housing section  58 . Clutch cover  55  may also be made in a single piece with transmission housing section  58 . Clutch cover  55  separates a wet chamber  56 , in which the two multiple-disk clutch arrangements  27  and  38  are positioned, from a dry receiving chamber  57 , in which vibration damping unit  8  is positioned. Clutch cover  55  has, radially on the inside, an essentially L-shaped end  60 , viewed in cross section, which projects into a ring chamber  62  that is formed by a section of clutch input part  24  with a U-shaped cross section. The U-shaped cross section of receiving chamber  62  contains a radially arranged base  64 , from which two legs  66  and  67  extend in axial direction. 
     Between clutch input part  24  and clutch cover  55  is a thin ring ball bearing  70 , which is supported in both the radial and the axial directions on end  60  of clutch cover  55  on the one hand, and on the base  64  and the leg  66  of clutch input part  24  on the other hand. Thin ring ball bearing  70  has a contact normal which is tilted from the radial direction. 
     Radially inside of and axially overlapping thin ring ball bearing  70  is a radial shaft seal ring  72 , positioned between end  60  of clutch cover  55  and clutch input part  24 . Thin ring ball bearing  70  is positioned completely in wet chamber  56 , which is separated from dry chamber  57  by a radial shaft seal ring  72 . Thin ring ball bearing  70  may be pre-mounted either on clutch cover  55  or on clutch input part  24 . The other part may slide over the corresponding bearing ring during assembly. In the area of the bearing device no additional axial retaining rings are necessary. Shifting of the parts toward transmission  5  is limited by stops  73  and  74  inserted in series on hub parts  30  and  41 , as well as a retaining ring  71  on second transmission input shaft  42 . The solution depicted in  FIG. 1  is also usable for single clutches. 
       FIGS. 2 and 3  show depictions similar to that in  FIG. 1 . The same reference numerals are used to designate the same parts. To avoid repetitions, we refer to the preceding description of  FIG. 1 . In the following description we will only go into the differences between the embodiments. 
     In  FIG. 2  an axial roller bearing  75  is positioned in the axial direction between clutch cover  55  and clutch input part  24 , radially outside the end  60  of clutch cover  55 . Radially inside of radial shaft seal ring  72  and axially overlapping it, a radial roller bearing  76  is positioned in the radial direction between leg  67  of clutch input part  24  and hub part  30 . The radial force here, in contrast to the solutions in  FIGS. 1 and 3 , is supported via hub  30  on transmission input shaft  31 . Both bearings may also be designed as journal bearings. 
     In  FIG. 3  a radial journal bearing device  78  having an axial thrust face is positioned between the end  60  of clutch cover  55  and clutch input part  24 . The journal bearing device  78  is positioned in wet chamber  56 .