Abstract:
A torque transmission device having a torque converter which is accommodated in the drivetrain of a motor vehicle, for transmitting torque between a drive unit and a transmission, has a converter housing that is rotationally mounted about an axis of rotation and is nonrotatably connected to the drive unit. The torsionally fixed connection between the drive unit and the converter housing includes a tubular connecting element that is located coaxially to the axis of rotation of the converter housing.

Description:
This claims the benefit of German Patent Application No. 10 2005 059 408.5, filed Dec. 13, 2005 and hereby incorporated by reference herein. 
   BACKGROUND INFORMATION 
   The present invention relates to a torque transmission device having a torque converter which is accommodated in the drivetrain of a motor vehicle, for transmitting torque between a drive unit and a transmission, and which has a converter housing that is rotationally mounted about an axis of rotation and is nonrotatably connected to the drive unit. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to devise a torque transmission device, which will be optimized with respect to space requirements, have a simple design, and be cost-effective to manufacture. 
   The present invention provides a torque transmission device having a torque converter which is accommodated in the drivetrain of a motor vehicle, for transmitting torque between a drive unit and a transmission, and which has a converter housing that is rotationally mounted about an axis of rotation and is nonrotatably connected to the drive unit, that the torsionally fixed connection between the drive unit and the converter housing includes a tubular connecting element that is disposed coaxially to the axis of rotation of the converter housing. The configuration of the connecting element creates a clearance space radially outside of the same in the axial direction between the drive unit and the converter housing, permitting a drive shaft, projecting from a differential gear, for example, to pass through perpendicularly to the axis of rotation of the torque converter. 
   One preferred exemplary embodiment of the torque transmission device provides for a fastening flange, which is attached to the converter housing, to extend from the end of the connecting element facing the converter housing. The fastening flange is preferably welded to the converter housing. 
   Another preferred exemplary embodiment of the torque transmission device provides for the fastening flange to project radially outwardly from the end of the connecting element facing the converter housing. This facilitates welding of the fastening flange to the converter housing. 
   Another preferred exemplary embodiment of the torque transmission device provides for the fastening flange to have a plurality of centering tabs which engage in centering recesses provided in the converter housing. This permits centering of the connecting element in relation to the converter housing in a simple manner. 
   Yet another preferred exemplary embodiment of the torque transmission device provides for the end of the connecting element facing away from the converter housing to be terminated by an end wall. The end wall enhances the stiffness of the connecting element. 
   Another preferred exemplary embodiment of the torque transmission device provides for the end wall to be integrally formed in one piece with the connecting element. This reduces the number of structural components requiring assembly or connection. 
   Another preferred exemplary embodiment of the torque transmission device provides for the end wall to have the shape of a circular disk having a bent-over peripheral region. The bent-over peripheral region is used for integrally joining, in particular welding, the end wall to the connecting element at any given axial positions. 
   Another preferred exemplary embodiment of the torque transmission device provides for the end wall to have a centering element. The centering element preferably projects from the end wall into an opening that is provided in an output shaft leading out from the drive unit. 
   Another preferred exemplary embodiment of the torque transmission device provides for a torque converter drive plate to be fastened to the end of the connecting element facing away from the converter housing. The torque converter drive plate is preferably secured on the drive side to a so-called flexplate, which is fastened, in turn, to an output shaft projecting from the drive unit. 
   Another preferred exemplary embodiment of the torque transmission device provides for the torque converter drive plate to have a tubular fastening portion from which a driving flange projects radially outwardly. 
   The tubular fastening portion of the torque converter drive plate is integrally joined, in particular welded, to the connecting element. 
   Another preferred exemplary embodiment of the torque transmission device provides for the torque converter drive plate and the connecting element to be integrally joined together to form one piece. This reduces the number of structural components requiring assembly or connection. 
   Other preferred exemplary embodiments of the torque transmission device provide for the connecting element to be a formed part, in particular a rollformed part. The connecting element is preferably integrally formed in one piece with the fastening flange, the end wall, and/or the torque converter drive plate. 
   Other advantages and features of the present invention and details pertaining thereto are derived from the following description in which various exemplary embodiments are explained in detail with reference to the drawings. In the accompanying drawings, the figures show: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a torque transmission device in accordance with a first exemplary embodiment, in half section. 
       FIG. 2  shows a torque transmission device in accordance with a second exemplary embodiment, in half section. 
       FIG. 3  shows a torque transmission device in accordance with a third exemplary embodiment, in half section. 
   

   DETAILED DESCRIPTION 
   A portion of a drivetrain  1  of a motor vehicle is illustrated in  FIG. 1 . Accommodated between a drive unit  3 , for example an internal combustion engine, a crankshaft  4  leading out therefrom, and a transmission  5 , is a hydrodynamic torque converter  6 . Crankshaft  4  of internal combustion engine  3  is fixedly connected via bolted connections  7  to a driving disk  8  which essentially has the shape of a radially extending annular disk. Driving disk  8  is referred to as a flexplate. A flywheel ring gear  9  is provided radially externally to driving disk  8 . 
   A fastening flange  11  of a torque converter drive plate  12  is secured by bolted connections  10  to the radially outer peripheral region of driving disk  8 . Radially inwardly, torque converter drive plate  12  has a tubular fastening portion  14 . Tubular fastening portion  14  is slid onto a tubular connecting portion  15  of a connecting element  16 . Connecting element  16  has the shape of a circular cylindrical surface, which is terminated at its drive-side end by an end wall  18 . End wall  18  is integrally formed in one piece with tubular connecting portion  15 . On the drive side, a mushroom-shaped centering element  20  is fastened to end wall  18 . Mushroom-shaped centering element  20  projects into a blind hole recessed in crankshaft  4 . 
   Fastening portion  14  of torque converter drive plate  12  is secured by weld seams  21 ,  22  to connecting element  16 . A fastening flange  24 , which projects radially outwardly, extends from the end of tubular connecting portion  15  of connecting element  16  facing transmission  5 . Fastening flange  24  is secured radially outwardly by a weld seam  25  to a housing  28  of torque converter  6 . Radially inwardly of weld seam  25 , fastening flange  24  has a plurality of centering tabs  26 , which engage in corresponding recesses of housing  28  of torque converter  6 . Housing  28  of torque converter  6  is rotatable about an axis of rotation  27  and is equipped with a drive-proximal housing wall  30  and a drive-distal housing wall  31 . Fastening flange  24  of connecting element  16  is secured to drive-proximal housing wall  30 . Drive-distal housing wall  31  is combined with an impeller  32  of hydrodynamic torque converter  6  to form one subassembly. 
   Interposed between impeller  32  and drive-proximal housing wall  30  is a turbine  34  which is secured radially inwardly to a turbine hub  35 . Turbine hub  35  is connected nonrotatably to an input shaft  36  of transmission  5 . Located between turbine  34  and impeller  32  is a stator  38  which is supported by a freewheel  39  on an impeller hub  40  that is mounted, for example, by way of a toothing on a housing-mounted tubular piece  42 . Interposed in a generally known manner between turbine  34  and drive-proximal housing wall  30  is a converter lockup clutch  44  having a torsional-vibration damper  46 . 
   Connecting element  16  allows a drive shaft  48 , which projects from a differential gear, to pass through perpendicularly to axis of rotation  27  between driving disk  8  and housing  28  of torque converter  6 . By compensating for the requisite height differential, tubular connecting portion  15  of connecting element  16  makes it possible for converter  6  to be connected. Connecting element  16  may be designed as a shaped sheet metal part and manufactured in a forming process. 
   Exemplary embodiments similar to those in  FIG. 2 through 3  are shown in  FIG. 1 . The same reference numerals are used to identify equivalent parts. To avoid repetitive explanations, reference is made to the preceding description of  FIG. 1 . In the following, only the differences between the individual exemplary embodiments are discussed in detail. 
   In the exemplary embodiment shown in  FIG. 2 , a torque converter drive plate  52 , which has a fastening flange  51 , is integrally formed in one piece with a tubular connecting portion  55  of a connecting element  56 . Drive-side end of tubular connecting portion  55  is terminated by a circular disk-shaped end wall  58  which has a bent-over peripheral region  59 . Bent-over peripheral region  59  of end wall  58  is configured on the inside of tubular connecting portion  55 . Fastened to end wall  58  is a mushroom-shaped centering element  60  which extends into a recess of crankshaft  4 . End wall  58  is secured radially outwardly by a weld seam  61  to connecting element  56 . The transmission-side end of tubular connecting portion  55  of connecting element  56  is butt-welded by a weld seam  65  to drive-proximal housing wall  30  of housing  28  of torque converter  6 . The exemplary embodiment shown in  FIG. 2  has the advantage that, viewed in the axial direction, end wall  58  is attachable at different locations radially inside of tubular connecting portion  55 . Accordingly, this exemplary embodiment may be adapted to different installation situations, without entailing substantial outlay. 
   In the exemplary embodiment shown in  FIG. 3 , a torque converter drive plate  72 , which has a fastening flange  71 , is integrally formed in one piece both with a tubular connecting portion  75  of a connecting element  76 , as well as with a drive-side, disk-shaped end wall  78 . As a result, the benefit is derived that connecting element  76  may be manufactured together with tubular connection portion  75 , end wall  78 , and torque converter drive plate  72 , as well as with fastening flange  71  using forming processes, in particular rollforming processes. Sheet metal may be used as feedstock for the forming processes, in particular rollforming processes. Fastened to end wall  78  is a mushroom-shaped centering element  80  which extends into a recess of crankshaft  4 . The transmission-side end of tubular connecting portion  75  of connecting element  76  is butt-welded by a weld seam  85  to drive-proximal housing wall  30  of housing  28  of torque converter  6 . 
   The term tubular can include perfectly tubular and substantially tubular. 
   LIST OF REFERENCE NUMERALS 
   
       
         1 . drivetrain 
         3 . drive unit 
         4 . crankshaft 
         5 . transmission 
         6 . torque converter 
         7 . bolted connection 
         8 . driving disk 
         9 . flywheel ring gear 
         10 . bolted connection 
         11 . fastening flange 
         12 . torque converter drive plate 
         14 . fastening portion 
         15 . connecting portion 
         16 . connecting element 
         18 . end wall 
         20 . centering element 
         21 . weld seam 
         22 . weld seam 
         24 . fastening flange 
         25 . weld seam 
         26 . centering tab 
         27 . axis of rotation 
         28 . housing 
         30 . housing wall 
         31 . housing wall 
         32 . impeller 
         34 . turbine 
         35 . turbine hub 
         36 . input shaft 
         38 . stator 
         39 . freewheel 
         40 . impeller hub 
         42 . tubular piece 
         44 . converter lockup clutch 
         46 . torsional-vibration damper 
         48 . drive shaft 
         51 . fastening flange 
         52 . torque converter drive plate 
         55 . connecting portion 
         56 . connecting element 
         58 . end wall 
         59 . peripheral region 
         60 . centering element 
         61 . weld seam 
         65 . weld seam 
         71 . fastening flange 
         72 . torque converter drive plate 
         75 . connecting portion 
         76 . connecting element 
         78 . end wall 
         80 . centering element 
         85 . weld seam