Abstract:
A spindle or worm drive for adjustment devices in motor vehicles. The device is secured with a fixed spindle or a fixed toothed rack to the first of two parts which can be adjusted in relation to each other, and is provided with a gear mechanism which is connected to the second of the two parts which can be adjusted in relation to each other. The gear housing is free from backlash and is enclosed by at least one bearing shell such that it is pivotable about at least one axis. The bearing shell consisting of two bearing plates which fit into one another and which can be joined to each other after enclosure of the gear housing. The gear housing is made of plastic and is provided with a concave or convex housing part which is surrounded by a convex or concave bearing shell section made of a material which is suitable for receiving crash forces, especially a metal material.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a National Phase Patent Application of International Application Number PCT/DE2002/04282, filed on Nov. 18, 2002, which claims priority of German Patent Application Number 102 06 524.1, filed on Feb. 13, 2002, and German Patent Application Number 102 50 994.8, filed on Oct. 30, 2002. 
     BACKGROUND 
     The invention relates to a spindle or worm drive for adjustment devices in motor vehicles, more particularly for seat adjustment devices, window lifters and sliding roofs. 
     From DE 198 61 100 A1 a spindle drive is known for adjustment devices in motor vehicles having a fixed spindle which is fixed on a first of two relatively rotatable parts, a gearing mechanism which is mounted on the second of the relatively rotatable parts, and a gear housing for accommodating the gearing. The gear housing consists of two housing plates which are fixed against each other by means of push-fit connections and which are designed as supporting connecting points where the housing plates are held together and which take up the gear forces. The push-fit connections have raised zones and recesses which fit into each other and initially form a play-fit. The housing plates are fixed by plastically deforming the material in the region of the push-fit connections. 
     From U.S. Pat. No. 4,802,374 a spindle drive is known for a seat longitudinal adjuster in motor vehicles which contains a spindle which is connected to the adjusting rail of the seat longitudinal adjuster and which can be driven through an electric motor by a spindle nut, worm wheel and a worm connected to a motor shaft. The worm, the worm wheel and the spindle nut are mounted in a retaining clip having two cylindrical sleeves which intersect at right angles. A retaining flange which is connected to the base rail of the seat longitudinal adjuster and consists of a clip with a rectangular window-shaped opening surrounds the cylindrical sleeves of the retaining clip through the frame of the window-shaped opening, and thus secures the position of the retaining clip. 
     With this spindle drive which is known from U.S. Pat. No. 4,802,374 the tolerances of the individual component parts determine the overall play of the spindle drive so that to reduce the clearance of the spindle drive narrow tolerances have to be set which requires considerable manufacturing expense. 
     A further drawback of the known spindle drives is that the retaining flange does indeed secure the position of the retaining clip but offers no security in the event of a crash since the retaining flange only surrounds a part of the retaining clip and in the event of a crash is bent so that the coupling between the movable adjusting rail and the base rail fixed on the body is released and thus a vehicle seat connected to the adjusting rail will move uncontrollably. 
     The object of the present invention is therefore to provide a spindle or worm drive for adjustment devices in motor vehicles of the type already described which guarantees a play-free bearing of the gear elements protected against dirt, a crash-safe connection of the gearing mechanism and thus of the adjustment device as well as a bearing of the gearing mechanism which is able to pivot when necessary about at least one axis. 
     BRIEF DESCRIPTION 
     The solution according to the invention provides a play-free bearing of the gearing elements protected against dirt as well as a crash-safe support of the gearing mechanism and thus of the relatively movable parts of the adjustment device as well as a pivotal action of the gearing mechanism for connecting adjustment parts which are able to pivot about an axis. 
     The solution according to the invention is based on the idea of arranging the gear elements in a gear housing surrounding the gear elements in the form of a capsule protected against dirt and damage and of arranging the gear housing in turn free from backlash and where necessary able to pivot about at least one axis in a bearing shell which is designed and intended to take up the crash forces and thus to ensure a crash-safe support of the gear mechanism so that the relatively movable parts of the adjustment device also remain connected together even in the event of a crash. 
     The gearing housing preferably consists of plastics while the bearing shell is made from a material, more particularly a metal material, which is suitable for absorbing crash forces. This enables on the one hand a simple manufacture of the gear housing, particularly in an injection casting process with high accuracy in fitting while the crash forces are taken up by the bearing shell which is made of metal so that the gear housing itself does not have to be dimensioned to take up the crash forces since these are distributed over a wide surface area over the gear housing through the bearing shell. 
     The ability of the gear housing to pivot about an axis, for example about a pivotal axis running perpendicular to the spindle or toothed rack is preferably achieved through a concave or convex housing part of the gear housing and a convex or concave bearing shell section which surrounds the concave or convex housing part. 
     In an exemplary embodiment of the drive the bearing shell is made in two parts; namely the bearing shell consists of two bearing plates which can be fitted into each other and which can be connected together after the gear housing has been fitted and which can be fixed on the second of the two parts which are adjustable relative to each other. 
     Making the bearing shell from two bearing plates which can be fitted into each other means that it is easy to fit the bearing shell free from backlash on the gear housing since the bearing plates can be placed around the gear housing, pushed together to zero tolerance and then connected together in this position, for example, by laser welding. 
     The preferably U-shaped bearing plates can be fitted together engaging in each other by means of the side arms in the direction of the longitudinal extension of the spindle or toothed rack whereby the connecting arms between the side arms have through openings for passing through the spindle or toothed rack, adjoined on each side by the concave or convex bearing shell sections which correspond with the convex or concave housing parts of the gear housing. 
     This design combines the rotational movement of the gear mechanism inside the bearing shell formed by the bearing plates with a clearance-free connection between the gear housing and the bearing shell with integrated guide of the spindle or toothed rack. 
     The side arms of the one bearing plate are preferably formed as tabs which engage in the other bearing plate in the one side arm provided with a window-shaped opening and the other side arm provided with a U-shaped recess. To compensate for tolerances, the tab-shaped side arm of the one bearing plate is longer in the connecting direction of the bearing plates than the window-shaped opening of the other bearing plate, and the tab-shaped side arm of the one bearing plate is shorter than the U-shaped recess of the side arm of the other bearing plate whereby the tab-shaped side arm of the one bearing plate can be fitted in the connecting direction of the bearing plates through a cut-out section in the connecting arm of the other bearing plate which widens out the window-shaped opening of the corresponding side arm of the other bearing plate. 
     Since the tab-shaped side arm of the one bearing plate in the connecting direction of the bearing plates is longer than the window shaped opening and the frame surrounding the window shaped opening is longer than the tab shaped side arm, the fixing points provided at the front ends of the tab shaped side arm in the connecting direction, and the frame surrounding the window-shaped opening are freely accessible for attaching the spindle or worm gearing on one of the two parts which are movable relative to each other. 
     In order to connect the bearing plates while guaranteeing a play-free coupling with the gear housing the side arms of the bearing plates are positively connected together in the assembled state of the adjustment device, more particularly through welding contours. 
     In a further exemplary embodiment of the drive the bearing shell is designed in four parts and consists of four bearing plates; where basically the bearing shell has a base plate, two side plates and a top plate, wherein the base plate and the top plate run substantially parallel to each other and are held spaced apart yet connected together through the two side plates which are mounted substantially parallel to each other. With this further special embodiment there is the important advantage that the manufacturing tolerances can be compensated particularly easily since the relative position of the four bearing plates (bearing shell plates) relative to each other can be re-aligned very simply. Thus the freedom from backlash between the gear housing and bearing shell can be adjusted and permanently fixed in a very simple manner. 
     In the further exemplary embodiment, the base plate optionally has two slot like openings of which one serves to hold a fixing tab of one of the two side plates and the other opening serves to hold the fixing tab of the other of the two side plates. 
     The one side plate can thereby advantageously have a further fixing tab which is mounted on a side of the side plate opposite the one fixing tab and engages in a recess in the edge of the top plate. 
     Through openings are advantageously provided in each of the side plates for passing through the spindle or toothed rack. 
     In order to fix the freedom from backlash between the gear housing and the bearing shell in a particularly secure manner it is regarded as advantageous if the side plates and the gear housing lie close against each other over a wide surface area. This can advantageously be achieved if the side plates have concave and convex bearing shell sections with which the gear housing is fixed. 
     The through openings in the side plates as well as the concave or convex bearing shell sections can thereby be arranged relative to each other so that the concave and convex bearing shell sections are arranged on each side of the through openings for passing through the spindle or toothed rack. 
     After the base plate, the two side plates and the top plate have been aligned relative to each other and the freedom from backlash between the gear housing and bearing shell is ensured, the base plate, the two side plates and the top plate can be welded together for fixing. In particular, laser welding is regarded as advantageous for fixing purposes. The welded seams for connecting the bearing plates should thereby lie in grooves which are formed in the connecting regions between the bearing plates which stand on one another. 
     An advantageous method for manufacturing the spindle and/or worm drive according to the invention includes the gearing elements after their connection with the spindle or toothed rack being inserted into a housing shell of the gear housing and being connected to a drive element of the motor shaft so that a gearing cover is connected to the housing shell of the gear housing to close up the gear mechanism and the finished made gear housing being enclosed free from backlash by a bearing shell. 
     In the case of a two part drive this can advantageously be fitted so that the bearing plates are pushed from both sides through the full-length openings onto the spindle, so that the side arms of the bearing plates are pushed into each other until the concave or convex bearing shell sections of the bearing plates adjoin without play against the concave and convex housing parts of the gear housing, and so that the abutting side edges of the side arms of the bearing plates are connected together by laser welding, at least over a part of their length. 
     The one end of the spindle can then be connected to a connecting tab which is fixed on the first of the two relatively rotatable parts and the interconnecting bearing plates can be connected to the second of the relatively rotatable parts. 
     In the case of a four-part bearing shell, it is regarded as advantageous if this is formed from four bearing plates in that two side plates are set up on a base plate, the gear housing is inserted between the two side plates, a top plate is fitted onto the two side plates and the four bearing plates are aligned without play relative to each other and then fixed together. 
     The two side plates can advantageously be fitted from both sides through window-shaped full-length openings onto the spindle and then aligned until the concave and convex bearing shell sections of the side plates bear without play against the concave and convex housing parts of the gear housing. 
     Fixing the four bearing plates can advantageously be carried out by welding, more particularly laser welding. In order to avoid “through welding” when laser welding, the join should be “butt” welded, thus welded at an obtuse angle. Laser welding should thereby be carried out in the grooved areas or in the grooves which are formed in the connecting region of the adjoining bearing plates. It is recommended in this connection if the laser welding is carried out at an angle of about 45° to the bearing plates which are to be connected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be explained in further detail with reference to the embodiment illustrated in the drawings. 
         FIG. 1  is a front exploded view of a first exemplary embodiment of a spindle or worm drive with a two part bearing shell. 
         FIG. 2  is top exploded view of the device of  FIG. 1 . 
         FIG. 3  is bottom exploded view of the device of  FIG. 1 . 
         FIG. 4  is front left perspective view of the device of  FIG. 1  in its assembled state. 
         FIG. 5  is front right perspective view of the device of  FIG. 1  in its assembled state. 
         FIG. 6  is front perspective view of the device of  FIG. 1  in its assembled state. 
         FIGS. 7-9  are front perspective views of three of four base plates used to form bearing shell with four bearing plates for a second exemplary embodiment of a spindle or worm drive with a four part bearing shell. 
         FIGS. 10-11  are front perspective views showing how a spindle or worm drive is connected with the bearings plates shown in  FIG. 9 . 
         FIG. 12  is a front perspective view of a top plate. 
         FIG. 13  is a front perspective view showing the finished assembled drive with the top plate of  FIG. 12  attached to the bearing plates of  FIG. 7-9 . 
         FIG. 14  is top perspective view showing the finished assembled drive of  FIG. 13 . 
         FIG. 15  is a detail showing how the four bear plates of  FIGS. 13 and 14  are connected and fixed together. 
         FIG. 16  is a detail showing the connection between a second side plate and a top plate of  FIG. 15 . 
     
    
    
     DETAILED DESCRIPTION 
     The spindle drive which is shown in exploded views in  FIGS. 1 to 3  has an electric motor  1  whose motor shaft  2  is connected to a drive worm  20  which meshes with a worm wheel  9  of a gear mechanism  3 . The worm wheel  9  is connected to a spindle nut  8  whose thread meshes with the thread of a spindle  7 . Any rotation of the motor shaft  2  is transferred through the drive worm  20  to the worm wheel  9  and thus to the spindle nut  8  which is connected in one piece to the worm wheel  9  so that when the spindle  7  is mounted rotationally secured it changes its position in relation to the motor shaft  2  through the rotation of the spindle nut  8 , i.e. is moved in the direction S 1  or S 2  in relation to the motor shaft  2  according to  FIG. 2  depending on the direction of rotation of the electric motor  1 . 
     The gear elements, drive worm  20 , spindle  8  and worm wheel  9 , are combined into the gear mechanism  3  which has a gear housing  4  which consists of a housing shell  40  and a housing cover  41  which after inserting the gear elements  8 ,  9 ,  20  into the housing shell  40  is connected to the housing shell  40 . 
     Two U-shaped bearing plates  5 ,  6  are fitted onto the ends of the spindle  7  projecting out from the gear housing  4 , wherein the side arms  52 ,  53  and  62 ,  63  of these bearing plates are aligned opposite one another and their connecting arms  51 ,  61  which connect the side arms  52 ,  53  and  62 ,  63  together have window-shaped through openings  55 ,  65  for receiving the spindle  7 . The side arms  52 ,  53 , and  62 ,  63  are thus designed so that they can engage in each other with slight play and thereby produce a positive connection which has a certain play. For this purpose the one bearing plate  5  has two side arms  52 ,  53  designed as tabs, while the one side arm  62  of the other bearing plate  6  has a rectangular window-shaped opening  66  while the other side arm  63  is designed U or clip-like and has a corresponding recess  67 . 
     If the two bearing plates  5 ,  6  are inserted in each other then the tab-shaped side arms  52 ,  53  of the one bearing plate  5  substantially fill out the window shaped opening  66  or the recess  67  of the side arms  62 ,  63  of the other bearing plate  6 . For compensating tolerances either the tab-shaped side arms  52 ,  53  of the one bearing plate  5  in the joining direction of the bearing plates  5 ,  6  are either slightly shorter than the length of the window-shaped opening  66  or recess  67  of the side arms  62 ,  63  of the other bearing plate  6 , or the tab-shaped side arm  52  of the one bearing plate is longer than the window-shaped opening  66  of the side arm  62  on the other bearing plate  6  and in the connecting direction of the bearing plates  5 ,  6  can be fitted through a cut out section  68  in the connecting arm  61  of the other bearing plate  6  which widens out the window shaped opening  66  of the corresponding side arm  62  of the other bearing plate  6  so that the tab shaped side arm  52  of the bearing plate  5  can project through the window shaped opening  66  and thus through the connecting arm  61  of the other bearing plate  6 , or the frame of the side arm  62  surrounding the window shaped opening  66  over the connecting arm  51  of the bearing plate  5 , as can be seen from the illustration in  FIG. 6 . After connecting the bearing plates  5 ,  6  into the bearing shell the fixing points  71 ,  72 ,  73  provided at the ends of the upper side arms  52 ,  62  of the bearing plates  5 ,  6  and projecting over the relevant connecting arms  51 ,  61  of the other bearing plate  5 ,  6  are accessible for fixing the spindle or worm gearing on the one of the two relative movable parts. 
     In the region of the window-shaped spindle passages  55 ,  56  through the bearing plates  5 ,  6  the connecting arms  51 ,  61  have in relation to the gear housing  4  concave curvatures  54 , 64  which correspond to convex housing sections  42 ,  43  of the gear housing  4 , i.e. the housing shell  40  and the housing cover  41 . The curvatures  42 ,  43  of the gear housing  4  and the curvatures  54 ,  64  of the connecting arms  51 ,  61  correspond with each other so that the gear mechanism  3  can swivel inside the bearing shell formed from the bearing plates  5 ,  6  about an axis running parallel to the motor shaft  2  and thus can compensate pivotal movements of the parts which are movable relative to each other, of which one part is connected through a fixing tab  70  to the spindle  7  and the other of the two relatively movable parts is connected through the fixing points  71 ,  72 ,  73  to the bearing shell which is formed by the bearing plates  5 ,  6 . 
     In order to assemble the spindle or worm drive the gear elements, namely the worm wheel  9  and the spindle nut  8 , after their connection with the spindle  7 , they are inserted into the housing shell  40  of the gear housing  4  and are connected to the worm  20  which is attached to the motor shaft  2 . After fitting the housing cover  41  onto the housing shell  40  and connecting it to the gear housing  4  the gear mechanism  3  is complete. The bearing plates  5 ,  6  are then pushed from both sides via the window shaped through openings  55 ,  65  onto the spindle  7  and the side arms  52 ,  53 ;  62 ,  63  of the bearing plates  5 ,  6  are pushed into each other and the concave and convex bearing shell sections  54 ,  64  of the bearing plates  5 ,  6  bear without play against the concave and convex housing parts  42 ,  43  of the gear housing  4 . Finally the abutting side edges  521 ,  522 ,  661 ,  662 ;  531 ,  532 ,  671 ,  672  of the side arms  52 ,  62  and  53 ,  63  of the bearing plates  5 ,  6  are connected together by means of laser welding which run as welding contours  74 ,  75 ,  76  at least over a part of the length of the side edges  521 ,  522 ,  661 ,  662 ;  531 ,  532 ,  671 ,  672 . 
     In order to connect the spindle or worm drive to the adjusting drive the one end of the spindle  7  is connected to the fixing tab  70  which is fixed on the first of the two relatively movable parts while the bearing plates  5 ,  6  which are connected together to form the bearing shell are connected to the second of the relatively movable parts. 
     In the assembled state of the gear mechanism  3  and the bearing shell formed from the bearing plates  5 ,  6  as illustrated in  FIGS. 4 to 6 , the side edges  521 ,  522  and  531 ,  532  of the tab-shaped side arms  52 ,  53  of the one bearing plate  5  are located adjoining the inner side edges  661 ,  662  and  671 ,  672  of the window shaped opening  66  and recess  67  respectively of the side arms  62 ,  63  of the other bearing plate  6 . As can be seen from the perspective illustrations of the assembled drive according to  FIG. 4 to 6 , the ends of the tab-shaped side arm  52  of the one bearing plate  5  and of the end of the side arm  62  of the other bearing plate  6  defining the window shaped opening  66  project over the relevant connecting arms  51 ,  61  of the relevant other bearing plate  5 ,  6  and enable a corresponding match to the dimensions of the gear housing  4  in the connecting region so that a play-free connection between the gear mechanism  3  and the bearing shell  5 ,  6  is guaranteed. 
     An embodiment for a drive according to the invention is shown in  FIGS. 7 to 16  where the bearing shell consists of four bearing plates. 
     In  FIG. 7  a base plate  800  is shown which has two slit like openings  810 . A side plate  820  with a fixing tab  830  is pushed into one of the two slit like openings  810  of the base plate  800 ; this is shown in detail in  FIG. 8 . The side plate  820  furthermore has a further fixing tab  840  which is described further below in connection with the fixing of the side plate  820  on a top plate. 
     In the illustration according to  FIG. 9  a second side plate  850  is pushed by its fixing tab  860  onto the base plate  800 . It can be seen in  FIG. 9  that the width of the slit like openings  810  is slightly larger than the width of the associated fixing tabs  830  and  860  so that the two side plates  820  and  850  have a slight clearance and thus are fixed easily movable on the base plate  800 . 
       FIGS. 10 and 11  show how the gear housing  4  already described in further detail above in connection with  FIGS. 1 to 6  is inserted with the electric motor  1  into the arrangement which comprises the base plate  800  and the two side plates  820  and  850 .  FIG. 10  thereby shows a view from inclined left and  FIG. 11  shows a view from inclined right. 
     Furthermore it can be seen in  FIGS. 10 and 11  that each of the two side plates  820  and  850  each has a through opening  870  and  880 . Left and right of the through openings  870  and  880 —thus on both sides of the through openings  870  and  880 —each of the two side plates  820  and  850  each has two concave and convex bearing shell sections  890 ,  900 ,  910  and  920 . The through openings  870  and  880  serve for passing through the spindle  7  which is shown in further detail for example in  FIG. 1  and which is described above in connection with  FIG. 1 . 
     In  FIG. 12  a top plate  930  is shown which has a recess  940  along the edge. The edge recess  940  serves—as described in detail further down in connection with FIGS.  13  to  16 —to receive the further fixing tab  840  of the one side plate  820 . 
       FIGS. 13 and 14  show the finished assembled drive after the gear housing  4  has been inserted between the two side plates  820  and  850 . In particular it can be seen easily from  FIG. 13  how the concave and convex bearing shell sections  890 ,  900 ,  910  and  920  bear  30  without clearance against the gear housing  4  which has a concave shape in the fixing area. In  FIG. 13  it can further be seen how the top plate  930  is fixed on the two side plates  820  and  850 . Also seen is the further fixing tab  840  of the one side plate  820  which engages in the recess  940  along the edge of the top plate  930 . On the side  950  of the top plate  930  opposite the edge recess  940  the top plate  930  rests on the second side plate  850 . 
       FIG. 14  shows the assembled drive from the back. It is possible to see the electric motor  1  and the base plate  800  as well as the slit like openings  810  into which the fixing tab  830  of the one side plate  820  as well as the fixing tab  860  of the second side plate  850  engage. Furthermore it is possible to see how the further fixing tab  840  of the one side plate  820  engages in the edge recess  940  of the top plate  930 . 
       FIGS. 15 and 16  show in detail how the four bearing plates  800 ,  820 ,  850  and  930  are connected and fixed together after the gear housing  4  has been inserted into the bearing shell  960  which is formed by these bearing plates. In the connecting regions between the bearing plates  800 ,  820 ,  850  and  930  there are grooved zones or grooves which carry the reference numerals  970 ,  980 ,  990  and  1000  in  FIG. 15 . The four bearing plates are thereby welded together in these grooved zones  970 ,  980 ,  990  and  1000 , thus through “grooved seam welding”. Grooved seam welding has the advantage over welding along the butt joints between adjoining connecting parts that no full penetrating welding passes through the seam point. 
       FIG. 15  also contains arrows  1010 ,  1020 ,  1030  and  1040  which are to represent the welding direction of a welding laser beam. It can be seen that the welding direction of the laser beam stands at an angle of about 45° to the bearing plates which are to be connected together. A particularly solid welding seam is formed by an angle of about 45°. The welding seams thus formed carry the reference numerals  1050 ,  1060 ,  1070  and  1080  in  FIG. 15 . 
     In  FIG. 16  the connection between the second side plate  850  and the top plate  930  is shown once more in detail. The groove  980  is shown into which the laser beam  1090  is directed. The laser beam  1090  thereby has an angle of about 45° to the second side plate  850  as well as an angle of about 45° to the top plate. “Full penetrating welding” can thus not occur.