Abstract:
The invention relates to a transmission drive unit ( 10; 40; 50; 70 ) having an adapter element made of plastic ( 22; 22   a;    53; 73 ) via which a torque is initiated by an input element ( 29 ) and a drive element ( 12; 12   a;    51; 72 ) made of metal for forwarding the torque, wherein the adapter element ( 22; 22   a;    53; 73 ) and the drive element ( 12; 12   a;    51; 72 ) are directly coupled to one another and rigidly connected, wherein the adapter element ( 22; 22   a;    53; 73 ) is an injection molded part which is formed by at least partial overmolding of the drive element ( 12; 12   a;    51; 72 ) and wherein the drive element ( 12; 12   a;    51; 72 ) serves as a bearing element.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a transmission drive unit. The applicant&#39;s subsequent publication DE 10 2009 000 760 A1 discloses a transmission drive unit which has an output element which is produced from metal, in particular from sintered metal, and is at least partially insert molded by an adaptor element designed as a worm wheel. The adaptor element is accommodated within a transmission housing. The adaptor element is mounted rotatably on an axle stub of the housing base, wherein both the axle stub and the adaptor element are composed of plastic. The previously known transmission drive unit which is designed in particular as a sliding roof drive can be produced relatively inexpensively by the adaptor element being injection molded on. The wear resistance of the known transmission drive unit is worthy of improvement in particular under high loads. Furthermore, force is introduced by the adaptor element to the output element over a relatively small axial length, and therefore the driving torque which can be transmitted is restricted. 
     SUMMARY OF THE INVENTION 
     Proceeding from the prior art described, the invention is based on the object of developing a transmission drive unit in such a manner that it permits good bearing properties and the possibility of transmitting relatively high torques while being able to be produced economically. This object is achieved with a transmission drive unit according to the invention. The invention is based on the concept of using the output element at the same time as a bearing element in order to improve the bearing properties. Since the output element is composed of metal, there is therefore the possibility of designing a metal/plastics bearing which is distinguished by improved wear resistance in comparison to a plastics/plastics bearing. 
     Particularly high torques can be transmitted if the output element is designed so as to be extended into a plane of symmetry of the adaptor element. As a result, the torque is introduced by the adaptor element in the plane of the output element. 
     A cost-effective radial mounting of the output element can be brought about if the output element has at least one region into which a journal serving for the mounting projects. 
     In an alternative refinement of the invention, the transmission drive unit can be produced particularly cost-effectively, wherein at the same time relatively high torques can likewise be transmitted. In this case, the invention is based on the concept of enabling the output element to be produced particularly simply and inexpensively by means of an output element which can be connected to the adaptor element and is designed as a deep drawn part. 
     The manufacturing can be configured in a particularly simple manner in this case if the output element is pressed onto the adaptor element. The pressing-on therefore constitutes a single installation step which can be very simply integrated into the manufacturing process. 
     As an alternative, provision is made for the adaptor element to be formed by at least partial insert molding of the output element. Such a formation permits a particularly intimate connection between the adaptor element and the output element, thus enabling particularly high torques to be transmitted. 
     In order to permit the torques to be transmitted, provision is made, in an advantageous refinement of the invention, for the output element to be of cup- or sleeve-shaped design and to have, on the inner surface thereof, at least one molding which interacts with a mating molding molded onto the adaptor element and connects the output element to the adaptor element for conjoint rotation. 
     In this case, particularly simple installation is made possible in the event of pressing on if the at least one molding and the at least mating molding are arranged obliquely in relation to the longitudinal axis of the output element. 
     Axial securing between the adaptor element and the output element, which securing is expedient in particular in the event of the output element being pressed onto the adaptor element, is made possible if the output element has, on an inner surface, at least one latching geometry which interacts with a mating geometry formed on the adaptor element and, in the process, axially secures the output element on the adaptor element. 
     A mounting which is particularly reliable and absorbs relatively high radial forces is brought about if the radial mounting of the unit consisting of the adaptor element and output element has two bearings having different diameters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages of the invention emerge from the description below of preferred exemplary embodiments and with reference to the drawings, in which: 
         FIG. 1  shows a first transmission drive unit according to the invention in a longitudinal section, 
         FIG. 2  shows an exploded illustration of an adaptor element and an output element, as used in the first transmission drive unit according to  FIG. 1 , 
         FIG. 3  shows a second transmission drive unit according to the invention in longitudinal section with an adaptor element which is changed in relation to  FIG. 1 , 
         FIG. 4  shows an exploded illustration of the output element and adaptor element, as used in a transmission drive unit according to  FIG. 3 , 
         FIG. 5  shows a third transmission drive unit according to the invention in longitudinal section, 
         FIG. 6  shows a unit consisting of the output element and adaptor element, as used in the third transmission drive unit according to  FIG. 5 , in a perspective view, 
         FIG. 7  shows a fourth transmission drive unit according to the invention in longitudinal section, 
         FIG. 8  shows an exploded illustration of an adaptor element and a drive element, as used in the transmission drive unit according to  FIG. 7 , 
         FIG. 9  shows a fifth transmission drive unit with a deep-drawn output element in longitudinal section, 
         FIG. 10  shows an exploded illustration of an adaptor element and output element, as used in the transmission drive unit according to  FIG. 9 . 
         FIG. 11  shows a perspective view of an output element according to  FIG. 10 , 
         FIG. 12  shows a sixth transmission drive unit according to the invention, in which the adaptor element is formed by insert molding of a deep-drawn output element, and 
         FIG. 13  shows a perspective view of an output element, as used in the transmission drive unit according to  FIG. 12 . 
     
    
    
     Identical components and components of identical function are provided with the same reference number in the figures. 
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a first transmission drive unit  10 , as provided in particular, but not restrictively, for use in a sliding roof drive of a motor vehicle. The transmission drive unit  10  has an output element which is composed of metal, in particular of sintered metal, and is designed as an output pinion  12 . In this case, the output pinion  12  constitutes the intersection with a sliding roof system which is in engagement with a transmission means (not illustrated) via an oblique external toothing  13  formed on the output pinion  12 . The adjustment of the roof mechanism is realized via the transmission means. 
     According to  FIG. 2 , the output pinion  12  has three sections  14  to  16 . The external toothing  13  is formed on the first section  14 . A second section  15 , which is of substantially sleeve-shaped design, adjoins the first section  14 . The second section  15  is surrounded approximately centrally by an annular third region  16  which has an encircling, web-like edge  17 . Molded ribs  18  arranged in a radiated manner are integrally formed on the lower side or upper side (not illustrated) of the third section  15 . As can be seen in particular from  FIG. 1 , the first section  14  has, on the inner wall thereof in the region of the external toothing  13 , a first receiving region  19  which is adjoined in the region of the second section  15  on the inner wall by a second receiving region  20 . 
     The output pinion  12  described to this extent is insert molded with an adaptor element which is composed of plastic and is designed as a worm wheel  22 , and is connected to said adaptor element by a form-fitting connection. As can be seen in particular with reference to  FIG. 1 , the second section  15  of the output pinion  12  preferably occupies the entire height of the worm wheel  22 , wherein the third annular section  16  of the output pinion  12  is located approximately in the plane of symmetry  23  of the worm wheel  22 . 
     The form-fitting connection between the worm wheel  22  and the output pinion  12  is reinforced in particular by the encircling edge  17  and the molded ribs  18  of the output pinion  12 , and therefore the output pinion  12  is connected to the worm wheel  22  for conjoint rotation. The worm wheel  22  has an inner region  24 , on the lower side of which a bearing collar  25  is molded. The external toothing  27  is connected to the worm wheel  22  via an annular central region  26 . The external toothing  27  of the worm wheel  22  is in engagement with an input element which is designed as a worm shaft  29  and forwards the driving torque of a driving motor (not illustrated) for the sliding roof drive to the worm wheel  22  and the output pinion  12 . 
     The unit  30  which is described to this extent and consists of the output pinion  12  and the worm wheel  22  injection molded onto the output pinion  12  is arranged, with the exception of a region of the output pinion  12 , within a transmission housing  31  composed of plastic. The transmission housing  31  comprises a housing lower part  32  which centrally has a molded-on bearing journal  33 . The bearing journal  33  has two regions  34  and  35  which serve for the radial mounting of the worm wheel  22  in the transmission housing  31 , for which purpose the first region  34  is in bearing contact with the first receiving region  19  of the output pinion  12  and the second region  35  is in bearing contact with the second receiving region  20  of the output pinion  12 . The worm wheel  22  is axially mounted in the transmission housing  31  via an annularly encircling web  36  which is molded onto the base of the housing lower part  32  and interacts with the bearing collar  25  on the lower side of the worm wheel  22 . A further, annularly encircling web  37  on the upper side of the worm wheel  22  is supported on a housing cover  38  which is connected to the housing lower part  32 , for example, by means of a latching or adhesive connection. In this case, the housing cover  38  has a centrally arranged aperture  39  through which the output pinion  12  protrudes out of the transmission housing  31 . 
       FIGS. 3 and 4  illustrate a second transmission drive unit  40  according to the invention. The second transmission drive unit  40  differs from the first transmission drive unit  10  substantially merely by the design of the output pinion  12   a  and of the worm wheel  22   a.  In this case, the output pinion  12   a  has, in the region of the second section  15   a,  a third section  16   a  which has gearwheel-like projections  42 . The projections  42  are located, as can be seen in particular with reference to  FIG. 3 , likewise substantially level with the plane of symmetry  23   a  of the worm wheel  22   a.  The projections  42  serve to form a form-fitting connection between the output pinion  12   a  and the worm wheel  22   a  in order to increase the torques which can be transmitted. The output pinion  12   a  is mounted analogously to the mounting of the output pinion  12  via a metal/plastics pairing between the output pinion  12   a  and the bearing journal  33   a  of the housing lower part  32   a.    
       FIGS. 5 and 6  illustrate a third transmission drive unit  50  according to the invention. The third transmission drive unit  50  comprises a sleeve-shaped output pinion  51  with an internal toothing  52  which serves for the form-fitting connection between the output pinion  51  and the worm wheel  53 . Furthermore, a bearing collar  54  is formed in the central region of the output pinion  51 , the outer wall  55  of which bearing collar serves as a first radial mounting of the output pinion  51  and of the unit  57 , which consists of the output pinion  51  and worm wheel  53 , in the transmission housing  58 . The bearing collar  54  here interacts with a passage bore  59  in the housing cover  60  composed of plastic. A second radial mounting of the unit  57  is formed between the bearing journal  61  in the housing lower part  62  and a bore  63  formed in the worm wheel  53 . In addition, a hexagon socket  64  which serves for the auxiliary actuation of the sliding roof drive, if the driving motor thereof should be defective, is also formed centrally in the output pinion  51 . The third transmission drive unit  50  therefore has two radial bearings for the unit  57 , the one bearing of which is designed as a metal/plastics pairing while the other bearing is designed as a plastics/plastics bearing. 
       FIGS. 7 and 8  illustrate a fourth transmission drive unit  70  which differs from the third transmission drive unit  50  substantially only in that the auxiliary actuation for the sliding roof drive is formed by means of the hexagon socket  71  in the worm wheel  73  instead of in the output pinion  72 . The fourth transmission drive unit  70  also has a first radial mounting of the output pinion  72  in the housing cover  74  while the worm wheel  73 , which is composed of plastic, is mounted radially in the region of a bearing journal  75  of the housing lower part  76 . The form-fitting connection between the output pinion  72  and the worm wheel  73  takes place in particular by means of web-like extensions formed on the inner wall of the output pinion  72  in the region of the first mounting. 
       FIGS. 9 to 11  illustrate a fifth transmission drive unit  80  according to the invention. In the fifth transmission drive unit  80 , the output pinion  81  thereof consists of a deep-drawn, cup-shaped sheet-metal part  82  which, in the region of the toothing  83  thereof, has radially inwardly projecting, obliquely arranged sections  84  which are formed by edges  86  on the side facing the worm wheel  85 . Furthermore, latching sections  88  formed on the inner wall are seen on a lower, annularly encircling section  87  of the output pinion  81 , which section faces the worm wheel  85 . The latching sections  88  interact with a circumferential groove  89  formed on the worm wheel  85 . The unit formed from the output pinion  81  and worm wheel  86  are manufactured in such a manner that the worm wheel  85  and the output pinion  81  are produced in separate processes. The output pinion  81  is subsequently pressed onto the worm wheel  85 , wherein the latching sections  88  interact with the circumferential groove  89  in the end position of the output pinion  81  such that the output pinion  81  is secured axially on the worm wheel  85 . 
       FIGS. 12 and 13  illustrate a sixth transmission drive unit  90  according to the invention. The sixth transmission drive unit  90  differs from the fifth transmission drive unit  80  essentially in that the worm wheel  92  of said sixth transmission drive unit is formed by insert molding of the output pinion  93  which is likewise designed as a deep-drawn part. In this case, the output pinion  93  according to  FIG. 13  has, on the side facing the worm wheel  92 , an annularly encircling collar  94  which, after said output pinion is insert molded by the plastic of the worm wheel  92 , fixes the output pinion  93  axially in the worm wheel  92 . Obliquely arranged depressions  95  which are formed on the inner wall of the output pinion  93  and, after having been injection molded from plastic, ensure that the output pinion  93  and the worm wheel  92  are secure against twisting, are likewise seen. The worm wheel  92  is mounted radially and axially likewise on two different diameters of a bearing journal  96 .