Abstract:
A hydrodynamic torque converter with a driving pump wheel and a drive turbine wheel that is placed in a housing in such a way that it can rotate is fixed to the drive shaft of a drive unit, and is connected to the housing with a converter bridging coupling that has a piston which remains fixed, with the help of a coupling spring mechanism, but which can be rotated in an axial direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation of International Patent Application Serial No. PCT/DE2007/000685, filed on Apr. 19, 2007, which application claims the benefit of priority from German Patent Application Serial No. 10 2006 020 743.2, filed on May 4, 2006, which applications are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a hydrodynamic torque converter with a driving impeller and a driven impeller which is rotatably disposed in a housing which is attachable to the output shaft of a drive unit, and provided with a torque converter lockup clutch which features a piston which is connected with the help of a coupling spring device non-rotatably, but movably with the housing in the axial direction. 
       BACKGROUND OF THE INVENTION 
       [0003]    In conventional torque converters, for instance, the piston is coupled with the help of preloaded leaf springs and coupled with the housing on drive side. The document U.S. Pat. No. 6,712,186 B1 depicts a hydrodynamic torque converter with a piston which is coupled by means of a tooth system without prestress with the housing. The U.S. Pat. No. 6,688,441 B1 document shows a hydrodynamic torque converter with a piston attached to the housing via a leaf spring. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    The object of the invention is to provide a hydrodynamic torque converter in accordance with the description below, which can transmit larger torque than conventional torque converters. 
         [0005]    The object is met with a hydrodynamic torque converter with a driving impeller and a driven turbine wheel which is rotatably disposed in a housing which is attachable to the output shaft of a drive unit, and having a torque converter lockup clutch which features a piston which is non-rotatably connected with the help of a coupling spring device, but is movably connected with the housing in the axial direction, wherein the piston is connected with the housing on the converter-side radially outside by means of the coupling spring device under axial prestress. Since the linking means takes place radially outside the housing, the radial design space of the torque converter lockup clutch can be omitted in the friction surface area, as a result of which the friction surface as well as the effective radius of the friction surface may be enlarged. Since the transmittable torque depends on the permissible surface pressure and the effectively acting friction lining surface, larger torque may be transmitted by enlarging the effective radius and friction surface. Furthermore, axial prestress can be achieved by linking the piston with the housing, for instance with a force of 300 Newton. Through this, the surface pressure may be increased advantageously. The converter can, for instance, be dimensioned for an engine torque of 400 Newton meter. This is advantageous, particularly because of radial expansion of the friction lining. It is advantageous in that this extension does not cause enlargement of housing dimensions of the hydrodynamic torque converter. Owing to the fact that the piston on converter side is connected with the housing, for instance, the effective radius of the friction lining can be enlarged by 10 to 12 mm, whereby the friction lining surface can be enlarged by approx. 10%. 
         [0006]    A preferred exemplary embodiment of the hydrodynamic torque converter is characterized in that the coupling spring device is interposed between the piston and a converter-side cover of the housing, wherein the piston features a first rim with a first tooth system and the converter-side cover features a second rim with a second tooth system. Non-rotatable coupling of the piston with the housing can take place advantageously via the tooth systems and the coupling spring device. In addition, it is possible through the tooth systems to keep the coupling axially displaceable. 
         [0007]    A further preferred exemplary embodiment of the hydrodynamic torque converter is characterized in that the coupling spring device features a drive synchronizer spring with V-shaped oppositely disposed spring elements, wherein the spring elements mesh with the first and second tooth system. The drive synchronizer spring of the coupling spring device can be formed of a suitable springy material, for instance, of a material with the initial CK75. The drive synchronizer spring can fulfill the task of a driving tab. In a particular case, the drive synchronizer spring can feature tooth systems complementary to the first and second tooth system which are in mesh with the latter and ensure coupling or synchronization of the piston. Therefore, the piston has the same speed of rotation as the housing of the hydrodynamic torque converter. In addition, the drive synchronizer spring can be formed as a spring-elastic element and abut on the corresponding rims of the piston and of the converter-side cover. As a result, the axial prestress of the piston can be applied against the friction lining of the torque converter lockup clutch. The functional manner is comparable with two diaphragm springs inside one another. It is moreover advantageous that the requirement of driving tab as well as axial press-on closure of the piston is fulfilled by a component, namely the driving tab or the drive synchronizer spring. 
         [0008]    A further preferred exemplary embodiment of the hydrodynamic torque converter is characterized in that the coupling spring device features a diaphragm spring ring. Here, the object of prestress and driving tab effect is likewise met by means of one component. 
         [0009]    A further preferred exemplary embodiment of the hydrodynamic torque converter is characterized in that the coupling spring device features a drive-side diaphragm spring which meshes with the first tooth system, and a converter-side diaphragm spring which meshes with the second tooth system, wherein the diaphragm springs are non-rotatably coupled with one another. In this case, the driving tab effect and prestress also occur via two diaphragm springs, wherein the attachment of individual diaphragm springs to the housing or piston occurs analogously. In contrast, the two easily manufactured diaphragm springs, for instance, are likewise non-rotatably coupled by suitable tooth systems. 
         [0010]    A further preferred exemplary embodiment of the hydrodynamic torque converter is characterized in that die coupling spring device features a leaf spring. As a result, the leaf spring can be disposed directly between the piston and the output-side cover of the housing, so that the radial design space likewise can be omitted. The leaf spring can be attached by means of usual connection techniques, for instance, by a rivet. It is considerable that the coupling spring device features several such leaf springs. 
         [0011]    A further preferred exemplary embodiment of the hydrodynamic torque converter is characterized in that the leaf spring is attached to a disk-shaped catch and piston. The disk-shaped catch can be coupled with the housing in the known manner, for instance, with the converter-side cover of the housing, for instance, via the second tooth system. To couple the disk-shaped catch with the piston again non-rotatably, the leaf spring can be attached to the piston and to the disk-shaped catch in the usual manner, for instance, by rivets. 
         [0012]    A further preferred exemplary embodiment of the hydrodynamic torque converter is characterized in that the diaphragm spring ring meshes with the first and the second tooth system. By meshing with the tooth system, the piston can be sustained at the rotation speed of the housing. To be able to mesh with the first and the second tooth system, the diaphragm spring rings feature appropriately form-closed, adapted teeth on the tooth systems. 
         [0013]    A further preferred exemplary embodiment of the hydrodynamic torque converter is characterized in that the diaphragm spring ring is attached to the housing via a splined disk carrier. The disk carrier can be attached to the housing in the usual manner, for instance, to the input-side cover of the housing. The disk carrier can feature cutouts, with which the tooth system of the diaphragm spring rings can mesh to transmit torque. In addition, the disk carrier can mesh with a corresponding tooth system of the piston, in order to couple it non-rotatably with the housing. 
         [0014]    A further preferred exemplary embodiment of the hydrodynamic torque converter is characterized in that the diaphragm spring ring is insertable in the disk carrier by means of form-closure. The diaphragm spring ring can be inserted advantageously in the disk carrier under prestress analogously to a bayonet closure. As soon as the diaphragm spring ring again relaxes, it can be held by the disk carrier under form-closure. 
         [0015]    The above specified task is moreover solved by a torque transmission device with a hydrodynamic torque converter, for torque transmission between a drive unit and a transmission, disposed in the power train of a motor vehicle, as described initially. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Further advantages features and details are derived from the following description with reference to the drawing, in which different exemplary embodiments are described in detail. The figures show the following: 
           [0017]      FIG. 1  shows a longitudinal section of a conventional torque transmission device; 
           [0018]      FIG. 2  shows a longitudinal section of a torque transmission device according to the invention, with a drive synchronizer spring; 
           [0019]      FIG. 3  shows a three dimensional exploded view of skewed front of the torque transmission device from  FIG. 2 ; 
           [0020]      FIG. 4  shows a detail view of a longitudinal section of an exemplary embodiment of the torque transmission device with an input-side diaphragm spring and a converter-side diaphragm spring; 
           [0021]      FIG. 5  shows a detail view of a further exemplary embodiment of a torque transmission device with a diaphragm spring ring; 
           [0022]      FIG. 6  shows a detail view of a longitudinal section of a further exemplary embodiment of a torque transmission device with a leaf spring bonded to a disk-shaped catch; 
           [0023]      FIG. 7  shows a detail view of a further sectional illustration of the disk-shaped carrier and the leaf spring of the torque transmission device in accordance with  FIG. 6 ; 
           [0024]      FIG. 8  shows detail view of a longitudinal section of a further torque transmission device with a leaf spring; 
           [0025]      FIG. 9  shows a detail view of a further sectional illustration of the leaf spring of the torque transmission device in accordance with  FIG. 8 ; 
           [0026]      FIG. 10  shows the plan view of a longitudinal section of a further torque transmission device with a diaphragm spring ring and a disk carrier; 
           [0027]      FIG. 11  shows a partially depicted plan in the perspective of arrow A from  FIG. 10  on the diaphragm spring ring and piston of the torque transmission device in accordance with  FIG. 10 , before and after the assembly of the diaphragm spring ring; and, 
           [0028]      FIG. 12  shows a partially depicted plan in the perspective of arrow A from  FIG. 10  on the diaphragm spring ring and piston of the torque transmission device in accordance with  FIG. 10 , before and after the assembly of the diaphragm spring ring. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    A part of power train  1  of a motor vehicle is depicted in  FIG. 1 . Hydrodynamic torque converter  6  is disposed between drive unit  3 , in particular, of an internal combustion engine, from which a crankshaft and transmission  5  protrude. The crankshaft of internal combustion engine  3 , for instance, is non-rotatably connected with housing  10  of torque converter  6 , via a drive plate that is also designated as flex plate. 
         [0030]    Housing  10  of torque converter  6  is rotatable about rotation axis  12  and is equipped with housing wall  14  near the drive and housing wall  15  far from the drive. On housing wall  14  near the drive, starter ring gear  17  is fixed with the help of connection plate  16  that extends radially outwards. Housing wall  15  far from the drive is combined in a module with impeller  20  of hydrodynamic torque converter  6 . 
         [0031]    Turbine wheel  21  is interposed between impeller  20  and housing wall  14  near the drive which is fixed on turbine wheel hub  22  with the help of rivet connection elements. Turbine wheel hub  22  is rotatably disposed on an output shaft or input shaft  23  of transmission  5 . Guide vane  24  is interposed in the usual manner between turbine wheel  21  and impeller  20 . Between turbine wheel  21  and housing wall  14  near the drive, torque converter lockup clutch  26  with torsional vibration damper  27  is likewise disposed in the usual manner. Torque converter lockup clutch  26  comprises piston  28  which is rotatably supported and is axially displaceable, radially outwardly on turbine wheel hub  22 . Piston  28  features a friction surface radially outwards which is facing internal combustion engine  3  and is disposed opposite a further friction surface which is provided on the side facing away from internal combustion engine  3  on housing wall  14  near the drive. Friction disk  29  is interposed between the two friction surfaces which are connected non-rotatably with clutch disk  30 . 
         [0032]    Clutch disk  30  is coupled, in the usual manner, with damper flange  35  of torsional vibration damper  27  under interposition of energy storage elements  33 , particularly of bow springs. Damper flange  35  is connected with damper hub  38  with the help of welded joint  36  in a form-closed manner. Damper hub  38  is again connected radially inside, non-rotatably with one end of input shaft  23  of transmission  5 . 
         [0033]    To prestress torque converter lockup clutch  26 , piston  28  is coupled with a leaf spring  41 . Coupling takes place in a required radial design space or coupling area between friction disk  29  of torque converter lockup clutch  26  and housing wall  14 . Leaf spring  41  is attached to housing  10  of torque converter  6 . The effective friction surface of friction disk  29  is also disposed radially within leaf spring  41  or coupling area of leaf spring  41  with piston  28 . 
         [0034]      FIG. 2  shows a longitudinal section of torque converter  6  according to the invention with coupling spring device  43 . In the following, differences from a known torque converter  6  are explained in accordance with  FIG. 1 , wherein same, similar and/or functionally similar components are provided with the same reference signs. Piston  28  is connected with housing  10  on converter side, radially outside by means of coupling spring device  43  under axial prestress. 
         [0035]    Housing  10  features drive-side cover  45  and converter-side cover  47 . In contrast to the illustration in accordance with  FIG. 1 , piston  28  is essentially disk-shaped and features a rim  49 . First rim  49  of piston  28  features first tooth system  51 . Converter-side cover  47  of torque converter  6  is likewise essentially disk-shaped and features second rim  53  with second tooth system  55 . 
         [0036]    Coupling spring device  43  meshes, in a form-closed manner, with first tooth system  51  of first rim  49  and with second tooth system  55  of second rim  53 . As a result, piston  28  is coupled non-rotatably with housing  10  of the torque converter. Piston  28  is connected with housing  10  on the converter-side, radially outside by means of coupling spring device  43  under axial prestress. Advantageously, friction disk  29  projects into the radial design space still required for coupling, according to the illustration of  FIG. 1 ; thus, it is also lengthened nearly up to housing wall  14 , through which a larger effective radius of torque converter lockup clutch  26  is advantageously obtained. The friction linings or friction surfaces of torque converter lockup clutch  26  are disposed adjacently to radial external housing wall  14 . This is possible, since coupling spring device  43  is disposed within the converter-side design space between piston  28  and turbine wheel  21 . 
         [0037]      FIG. 3  shows a three dimensional exploded view of torque converter  6  depicted in  FIG. 2  obliquely from the front. It is apparent that coupling spring device  43  features drive synchronizer spring  57 . Drive synchronizer spring  57  features V-shaped spring elements  59  on the opposite side. In the assembled state, spring elements  59  can be brought onto abutments  61  of the corresponding first and second tooth system  51  and  55 , respectively, and thus under prestress. By means of arrow  63  it is hinted that spring elements  59  of drive synchronizer springs  57  keep piston  28  under prestress via abutments  61  which act on friction surface  65  of drive-side cover  45 . 
         [0038]      FIG. 4  shows a longitudinal section of a detail of torque converter  6  with a further coupling spring device  43  which features drive-side diaphragm spring  67  as well as converter-side diaphragm spring  69 . Drive-side diaphragm spring  67  meshes with first tooth system  51  of first rim  49 . Converter-side diaphragm spring  69  meshes with second tooth system  55  of second rim  53  of converter-side cover  47 . For non-rotatable coupling of piston  28  with housing  10 , diaphragm springs  67  and  69  moreover feature tooth system  71  respectively, through which diaphragm springs  67  and  69  can be coupled mutually non-rotatably. The torque flow occurs also, starting from second rim  53  via tooth systems  55 ,  71  and  51  and finally to first rim  49  of piston  28 . 
         [0039]      FIG. 5  shows a detail view of a further torque converter  6  with diaphragm spring ring  73 . Diaphragm spring ring  73  features annular spring leaf  75 . Spring leaf  75  of diaphragm spring rings  73  features bent sections  77  which realize tooth system  79 . For non-rotatable coupling of piston  28  with second rim  53  of converter-side cover  47 , tooth system  79  meshes with first tooth system  51  of first rim  49  of piston  28 . On the opposite side, spring leaf  75  features tooth system  81  which meshes with second tooth system  55  of converter-side cover  47 . Thus, via a single component, namely diaphragm spring ring  73 , its spring leaf  75  and tooth systems  79  and  81 , non-rotatable coupling and prestress of piston  28  as well can occur advantageously. 
         [0040]      FIG. 6  shows a further longitudinal section of a detail view of torque converter  6  with leaf spring  83  and disk-shaped catch  85 . Disk-shaped catch  85  meshes with second tooth system  55  of the converter-side cover of housing  10 . Catch  85  is non-rotatably attached to leaf spring  83 , wherein the attachment occurs via rivet  87 . Leaf spring  83  is attached to piston  28  under prestress. 
         [0041]      FIG. 7  shows a partially broken illustration, viewed in the alignment of  FIG. 6 , from the top with a partial auxiliary section and a partial section of carrier  85  of leaf spring  83  and of piston  28  as well. Through the auxiliary section, rivet  87  is visible. The attachment of leaf spring  83  to piston  28  takes place likewise via rivet  89 . Arrow  63  hints at the direction of force of leaf spring  83  necessary to prestress piston  28 . 
         [0042]      FIG. 8  shows a further sectional illustration of a detail of torque converter  6  with leaf spring  83 . In contrast to the illustration according to  FIGS. 6 and 7 , no catch  85  is provided according to  FIG. 8 . Instead of carrier  85 , leaf spring  83  features bent fixing plate  91 . Leaf spring  83  can be attached directly on drive-side cover  45  by means of fixing plate  91  and rivet  87 . 
         [0043]      FIG. 9  shows a sectional illustration of leaf spring  83 , viewed in the alignment direction of  FIG. 8 , from the bottom onto fixing plate  91 , wherein the cutting plane runs through rivet  89  of leaf spring  83  with piston  28 . In  FIG. 9 , drive-side cover  45  and rivet  87  are not depicted. Fixing plate  91  features two bores  93 , in which two rivets  87  can be fixed. 
         [0044]      FIG. 10  shows a further longitudinal section of a detail view of torque converter  6  with diaphragm spring ring  95  and disk carrier  97  as well.  FIGS. 11 and 12  show a plan view of diaphragm spring ring  95  and disk carrier  97  as well viewed from the direction of arrow A from  FIG. 10 .  FIG. 11  shows the diaphragm spring ring in the applied state within disk carrier  97 . 
         [0045]      FIG. 12  shows diaphragm spring ring  95  after a partial rotary motion which is hinted by arrow  99 . In  FIG. 12  it is apparent that diaphragm spring ring  95  can be held analogously to the functioning manner of a bayonet closure, in a form-closed manner, within recess  101  of the disk carrier. To execute a rotation, as hinted by arrow  99 , the diaphragm spring ring must first be brought under prestress in the drawing plane of  FIGS. 11 and 12  so that teeth  103  of tooth system  105  of diaphragm spring ring  95  can slide through recess  101  of disk carrier  97 . Recess  101  is formed by cutouts  107  located opposite of disk carrier  97 . Furthermore, a tooth system of disk carrier  97  is realized by cutouts  107 . Tooth system  109  of disk carrier  97  serves on the one hand for bayonet-closure type of fixation of diaphragm spring ring  95 , as already described, and on the other hand for non-rotatable coupling of piston  28  with drive-side cover  45  of housing  10 . Here, for instance, disk carrier  97  is non-rotatably attached to drive-side cover  45  by means of weld  111 . For axially relocatable, non-rotatable coupling of piston  28 , tooth system  109  of disk carrier  97  moreover meshes with tooth system  113  of piston  28 . 
         [0046]    For assembly, first piston  28  can be inserted inside drive-side cover  45 . Afterwards, diaphragm spring ring  95 , as described above, can be mounted like a bayonet closure, so that it interlocks in disk carrier  97 . The diaphragm spring ring can rest on disk carrier  97  in order to generate the required prestress and at the same time it is secured against rotation. The direction of prestress force which acts through piston  28  corresponds to the direction of view as hinted by arrow A. 
       REFERENCE LIST 
       [0000]    
       
           1  power train 
           3  drive unit 
           5  transmission 
           6  torque converter 
           10  housing 
           12  rotation axis 
           14  housing wall 
           15  housing wall 
           16  connection plate 
           17  starter ring gear 
           20  impeller 
           21  turbine wheel 
           22  turbine wheel hub 
           23  input shaft/drive shaft 
           24  guide vanes 
           26  torque converter lockup clutch 
           27  torsional vibration damper 
           28  piston 
           29  friction disk 
           30  clutch disk 
           33  energy storage element 
           35  damper flange 
           36  welded connection 
           38  damper hub 
           41  leaf spring 
           43  clutch spring device 
           45  drive-side cover 
           47  converter-side cover 
           49  first rim 
           51  first tooth system 
           53  second rim 
           55  second tooth system 
           57  drive synchronizer spring 
           59  spring elements 
           61  abutment 
           63  arrow 
           65  friction surface 
           67  drive-side diaphragm spring 
           69  converter-side diaphragm spring 
           71  tooth system 
           73  diaphragm spring ring 
           75  spring leaf 
           77  bent section 
           79  tooth system 
           81  tooth system 
           83  leaf spring 
           85  catch 
           87  rivet 
           89  rivet 
           91  fixing plate 
           93  bore 
           95  diaphragm spring ring 
           97  disk carrier 
           99  arrow 
           101  recess 
           103  teeth 
           105  tooth system 
           107  cutout 
           109  tooth system 
           111  weld 
           113  tooth system