Abstract:
The invention relates to a gear for adjusting two parts ( 60, 61 ) that can be displaced in relation to each other, particularly vehicle parts of a seat adjustment device, of a window lifter or of a sliding roof, wherein the first one of the parts ( 60 ) comprises a non-rotatable spindle ( 62 ) or a fixed toothed rack. The gear comprises a worm wheel ( 4, 41 ), with a spindle nut ( 42 ) non-rotatable thereto for driving the spindle ( 62 ) or a worm non-rotatable thereto for driving the toothed rack, a drivable worm ( 3, 31 ) for transmitting a driving force to the worm wheel ( 4, 41 ) and a gear housing ( 1 ), which accommodates and supports the worm ( 3 ) and the worm wheel ( 4 ) and which can be non-rotatably connected to the second one of the parts ( 61 ) in the displacement direction thereof, the gear housing ( 1 ) being formed by a single-piece body with a worm bearing ( 14 ) and a worm wheel bearing ( 19 ).

Description:
The present inventive subject matter relates to a gear for adjusting a vehicle seat and further relates to a vehicle seat having such a gear. 
     BACKGROUND 
     EP 0 979 750 A2 describes a vehicle seat comprising an adjusting device with a spindle and an associated spindle nut. The spindle is fixed to a first adjustment element of the adjusting device. The spindle nut can turn in a second adjusting element, wherein the second adjusting element together with the first adjusting element is mounted in sort of a rail guide. With its outer casing, the spindle nut forms a worm wheel, which is engaged with a worm of a drive unit. The arrangement serves the displacement of a vehicle seat attached to the second adjusting element in relation to the first adjusting element, which is fixed to the vehicle bottom. The disadvantage associated with this arrangement is that it comprises a plurality of individual components, which must be disposed and attached directly in the rail arrangement formed by the two adjusting elements. Any potentially necessary repairs are therefore associated with great expenses. 
     U.S. Pat. No. 4,802,374 describes a control drive for a vehicle seat, wherein such a spindle is non-rotatably connected to a vehicle seat rail forming an adjusting element. The spindle, however, is fastened outside the rail guide, which is considered undesirable by vehicle manufacturers. A further seat adjustment device with a self-locking adjusting drive for vehicle seats is known from DE 1 755 740. Also in this arrangement, a plurality of components is disposed adjacent to a rail guide. 
     A gear arrangement with complex design for adjusting a vehicle seat is known from WO 02/070299 A1. This arrangement has a gear with complex design, which gear is intended to accommodate forces occurring in the event of an accident. 
     EP 1 068 093 B1 discloses a gear, as that illustrated according to  FIG. 3 , which is used to adjust two elements  60 ,  61  in relation to each other, particularly vehicle elements of a seat adjustment device, a window lifter or a sliding roof, wherein the first of the parts  60  forms a lower rail firmly connected to the vehicle bottom, which rail receives a locked spindle  62  or a fixed toothed rack. The gear  6  is located on the spindle  62  and displaced back and forth along the spindle  62  upon actuation. The gear  6  is received in a mount  63 , which is displaced back and forth together with the second of the adjustable elements  61 . The mount  63  is fixed to the second of the elements  61  adjustable in relation to each other, which second element forms a top rail that is adjustably connected to the bottom rail. The upper rail is connected to further components of the vehicle seat via a retaining plate  64 . Furthermore, a drive mechanism  66  is attached to the retaining plate  64  using fastening elements  65 , the drive shaft  67  of which mechanism is connected to a drivable worm of the gear  6 . 
     The gear  6  comprises a worm wheel, with a spindle nut locked thereto for driving the spindle or a worm locked thereto for driving the toothed rack, a drivable worm for transmitting a driving force from the drive mechanism to the worm wheel and a gear housing, which receives and supports the worm and the worm wheel and is connected non-displaceably to the second of the adjustable elements  61  in the displacement direction. The gear housing comprises a plurality of, but at least two, housing plates that are fixed against each other with plug-type connectors. The plug-type connectors fix the positions of the housing plates in relation to each other in all three-dimensional directions, wherein the plug-type connectors are configured at the same time as supporting connecting joints, which absorb the gear forces. If only two housing plates are provided, the gear housing comprises two L-shaped housing plates. If at least four elements are provided, the gear housing comprises at least two pairs of mutually opposed disk-shaped housing plates, wherein in any case a complex gear arrangement is provided, which in addition to the housing elements necessitates a plurality of further bearing elements or bearing support elements, such as washers. Apart from the complex assembly of a plurality of individual components, it is also disadvantageous that the tolerances of the individual components must be adapted to each other. The individual housing elements of such a gear housing are connected by welding. 
     Furthermore it has been known to provide two individual pressure housing elements, which are equipped with a spindle nut, driver plates and bearing bushings as well as a worm and associated bearing bushings and are then closed through plastic deformation of plug-type connectors of the housing halves. 
     DE 36 40 197 A1 describes a drive apparatus for an adjustable power seat with a two-piece housing. In two opposed walls of the housing, respectively, a bore is formed for accommodating the shaft of a worm or of a worm wheel. So as to be able to support the shaft projecting from one end of the worm, a cover is inserted in front of the bore, which cover on the inside comprises a plug for supporting the shaft. In terms of the support of the worm wheel and the wheel, this concept has a two-piece housing, which is formed by a main housing and the absolutely required cover in terms of its function. 
     EP 0 992 711 A2 describes a gearbox for receiving a worm and a worm wheel, through each of which a shaft extends. The two shafts are mounted in two opposing recesses, wherein the recesses are formed by corresponding through-bores through the opposite side walls. So as to insert the worm wheel and worm in the housing, the housing comprises two members, wherein the respective parting line through the side walls extends at the center through the through-bores. After inserting the shafts of the worm and worm wheel in the recesses of the lower housing member, the upper housing member is placed on top and they are screwed together. 
     DE 41 04 470 C1 describes a car seat adjuster with a housing, in which a spindle nut and a threaded spindle are accommodated. The housing is a two-piece housing comprising a main housing element and a cover for closing the main housing element. A borehole is formed in a housing wall for receiving a drive shaft. The borehole extends laterally in a slot shape to an outside wall, which can be closed with the cover. The width of the slot corresponds to more than the width of the drive shaft and the width of the receiving section for the drive shaft in its respective functional position. Furthermore, the housing is very complex and comprises a plurality of individual wall and support elements. 
     DE 37 25 158 C2 relates to a power seat apparatus for an automotive vehicle, wherein a multi-piece housing with a worm and a worm wheel is shown. A plurality of different components are used for supporting the worm and worm wheel. DE 37 26 801 C2 relates to a worm gear with a housing, wherein the housing is divided by a partitioning plane that includes the driving axle and is disposed perpendicular to the driving axle, so that upon separation of the two housing members an opening is formed for inserting the worm wheel and worm. DE 35 19 058 C2 describes a seat adjustment for a motor vehicle seat with a complex housing for accommodating a worm and a worm wheel. A shaft is mounted in a U-shaped support, which is closed by a flat cover-shaped element in order to prevent the shaft from sliding out of the support. DE 29 25 032 C2 describes a drive unit for a seat adjustment with a multi-piece housing for accommodating a worm and a worm wheel. Particularly support elements, which are included in the housing parts as separate components, serve the support of shafts. DE 29 03 782 A1 relates to an adjustment mechanism with a complex design for receiving a worm and a worm wheel, wherein they are accommodated in special bearing elements. 
     SUMMARY 
     It is the object of the invention to simplify a gear for adjusting two elements that can be displaced in relation to each other, particularly vehicle elements of a seat adjustment device. In particular, the number of elements required is intended to be reduced and simpler assembly and/or replacement of gear elements are supposed to be possible. 
     This object is attained with a gear for adjusting two elements that can be displaced in relation to each other, with the characteristics of claim  1 . The object of claim  10  is a spindle or worm drive mechanism with a gear of this type. The object of claim  11  is a vehicle seat with a gear of this type. Advantageous embodiments are disclosed in the dependent claims. 
     Advantageously, drive mechanisms identical in design are used for left and right seat rails if the worm used and/or the worm wheel used are configured axially on both sides for inserting or guiding through a drive shaft. It is preferred if the drive shaft is connected to the worm with a square socket, which is provided in the worm on both sides or through it. 
     Accordingly, it is preferred to use a gear for adjusting two elements that can be displaced in relation to each other, particularly vehicle elements of a seat adjustment device, a window lifter or a sliding roof, wherein the first one of the parts has a non-rotatable spindle or a fixed toothed rack and wherein the gear is configured with a worm wheel, which has a spindle nut non-rotatable thereto for driving the spindle or a worm non-rotatable thereto for driving the toothed rack, with a drivable worm for transmitting a driving force to the worm wheel and with a gear housing, which receives and supports the worm and the worm wheel and which can be connected non-displaceably to the second one of the parts in the displacement direction thereof, wherein the gear housing is made of a single-piece body with a worm bearing and a worm wheel bearing. 
     It is preferred to use a gear, wherein the worm bearing is formed in one or two opposite walls, particularly in the form of side walls of the gear housing, above all in the top section of the gear housing, and in the insertion direction of the worm comprises a worm bearing access opening, with the worm bearing access opening extending through the corresponding side wall to the bottom of the side wall and/or of the gear housing. 
     It is preferable to use such a gear in which the worm bearing access opening or a section in the transition region between the worm bearing access opening and the worm bearing has a smaller distance than the diameter of a worm shaft of the worm. 
     It is preferred to use a gear in which the worm wheel bearing is formed in one or two opposite walls, particularly beneath the upper worm, and comprises a worm wheel bearing access opening, with the worm wheel bearing access opening extending through a corresponding side wall to the bottom of the side wall and/or of the gear housing. 
     It is preferable to use such a gear in which the worm wheel bearing access opening or a section in the transition region between the worm wheel bearing access opening and the worm wheel bearing has a smaller distance than the diameter of a worm wheel shaft of the worm wheel. 
     It is preferable to use a gear in which the side walls with the worm bearing are configured between the side walls with the worm wheel bearing. In a simple embodiment, the side walls with the worm wheel bearing form the fronts of a housing and the side walls with the worm bearing form the two walls between the fronts. In a view from above, these four walls thus form side walls of a square or cuboid housing. Other embodiments, however, are also conceivable, for example one in which two of the opposite walls extend to the two other walls at an angle between a worm axis and a worm wheel axis, the angle theoretically ranging between 1 and 179°. 
     Preferred is a gear, in which the side walls in the bottom section of the gear housing are formed by mutually spaced legs, with the distances of two adjoining legs as worm bearing access openings for the purpose of guiding through a worm shaft and/or as worm wheel bearing access openings for guiding through a worm wheel shaft are dimensioned wide enough and/or elastic enough. 
     Preferable is such a gear that has a housing closure element for closing the bottom of the gear housing, the housing closure element fixing the legs against each other after inserting the housing closure element. A housing closure element of this type can be implemented particularly in the form of an encompassing pan or in the form of a pin design. 
     Preferable is a gear with a housing closure element for closing the bottom of the gear housing, in which the housing closure element supports the worm wheel and/or the worm in the gear housing from beneath. 
     Preferable is a gear, in which at least one inside side wall towards the worm bearing access opening or towards the worm wheel bearing access opening has an insertion taper. 
     This advantageously simplifies the design and assembly of such a gear accordingly. In the simplest case, this is done by reducing the number of components to three particular ones, namely a single-piece gear block as the gear housing, a worm and a spindle nut. The worm and spindle nut used can have the conventional designs, with the spindle nut having particularly an enveloping row of teeth with a cylindrical portion. The gear block may be produced easily and at the same time cost-efficiently, for example, as a polymer injection-molded part with accordingly integrally formed recesses for gearing elements. The individual components, meaning particularly the worm and spindle nut, are inserted in the gear block using appropriate receiving devices and/or feed devices to the bearings and are supported therein rotatably about the respective longitudinal axis using a snap-fit or detent connection. According to a preferred embodiment, a gear cover is snapped into corresponding detent elements from beneath as a housing closure element in order to secure the combination of worm wheel and spindle nut in the gear housing. 
     It is preferred if a gear with such very small dimensions is used between two seat rails, functioning as the elements of a vehicle seat that can be displaced relative to each other. In principle, however, the use in various applications of worm gears can be implemented. 
     One exemplary embodiment will be explained in more detail hereinafter with reference to the drawing, wherein: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a gear housing with inserted worm and inserted worm wheel according to a particularly preferred embodiment; 
         FIG. 1A  is a sectional view of such an arrangement; 
         FIG. 2  shows the elements of the arrangement according to  FIG. 1  in exploded view; and 
         FIG. 3  is a schematic illustration of individual elements of a vehicle seat frame and rail guide with a gear according to the prior art. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show assembled and exploded views of a gear and the components thereof according to a particularly preferred embodiment. A single-piece gear housing  1  serves to accommodate a worm  3  and a worm wheel  4 . The arrangement can optionally be closed from beneath using a housing closure element  2  or a housing cover. 
     The gear housing  1  comprises an upper element  10 , on the bottom corner regions of which legs  11  or bar-shaped extensions are integrally formed and directed downward. The spatial directions above and below in the present embodiment serve only illustration purposes since the assembled gear can ultimately be inserted in a drive mechanism in arbitrary spatial directions. 
     So as to support the worm  3 , a receiving or worm space  12  is formed in the upper element  10  of the gear housing  1 . As is known from prior art, the worm  3  comprises a worm shaft  30  and worm teeth  31 , which are formed in the center region of the worm shaft  30  around the same. As is apparent particularly from  FIG. 1A , both ends of the worm shaft  30  preferably have drive shaft mounts  32  serving the fastening of a drive shaft to the worm shaft  30 , so that the worm  3  can be rotated about the longitudinal axis X thereof. An arrangement of this mount on both sides, or a through-arrangement of a drive shaft mount  32 , allows the provision of drive mechanisms for left and right seat rails with identical designs. Using one and the same drive mechanism is useful in that a drive shaft  67  can be inserted axially on both sides or that it can extend through. It is preferable if the drive shaft mount  32  is configured in the worm  3  as a square socket on both sides or through it. 
     Before inserting the worm  3  in the worm space  12 , it is preferable to place annular bearing disks  33  on the two worm shaft ends  30 , which project from the worm  3  on both sides of the worm teeth  31 . This, however, is not absolutely required and may be foregone in the event of an enveloping row of teeth with cylindrical portion, for example. 
     Worm bearings  14  are formed in two mutually opposed first side walls  13  of the upper part  1  [sic] 1  of the gear housing  1 , which part forms the worm space  12 . At least one of the worm bearings  14  is configured as a through-bore through the corresponding first side wall  13  in order to allow the corresponding worm shaft  30  and/or the drive shaft attached thereto to pass through the first side wall  13 . The open diameter of the worm bearing  14  is larger than the diameter d 3  of the worm shaft  30 . It is preferable if the design allows minimum clearance.  1  Translator&#39;s note: Reference numeral should be  10   
     For inserting the worm  3  in the worm bearing  14 , worm bearing access openings  15  are integrated in the first two side walls  13 , which openings extend from the worm bearing  14  to the bottom of the upper element  10  or the corresponding first side walls  13 . This allows the worm  3  to be inserted in the worm bearing  14  from beneath, wherein the ends of the worm shaft  30  are guided through the two corresponding worm bearing access openings  15 . 
     So as to retain the worm  3  in the worm space  12 , according to a simple embodiment the worm wheel  4  may be inserted in the gear housing  1  from beneath and be supported therein such that the worm  3  is securely supported in the worm bearing  14  and also supported towards the bottom by the worm wheel. 
     According to the preferred embodiment, however, the wall of the worm bearing access opening  15  has a transversely, meaning particularly parallel to the worm axis X, extending bar as a retaining bar  16 . An open distance d 4  between the retaining bar or bars  16  on the two opposite walls of the worm bearing access opening  15  is smaller than the diameter d 3  of the worm shaft  30 . The wall of the gear housing  1  in the region of at least the worm bearing access opening  15  and/or the wall of the worm shaft  30  are made of elastic material, which yields when inserting the worm  3  in the worm bearing  14  through the worm bearing access openings  15 . After inserting the worm shaft  30  above the retaining bar or bars  16 , the worm shaft  30  with the two ends thereof is rotatably supported in the worm bearing  14 , wherein the retaining bars  16  prevent the shaft from sliding downward out of the worm bearing  14 . 
     The worm wheel  4  comprises in the familiar fashion a worm wheel shaft  40 , which protrudes from worm wheel teeth  41  with both ends. The worm wheel  4  is configured such that it can rotate about a worm wheel axis Y, wherein the worm wheel axis Y at the same time forms the axis of rotation of a spindle nut  42 . The spindle nut  42  is formed by inside teeth of the worm wheel shaft  40 , which is configured as a hollow shaft. The spindle nut  42  serves to accommodate a spindle, which during operation of the gear, for example in the guide rails of a vehicle seat, meshes with a spindle disposed non-rotabably in one of the rails. Upon rotating the worm wheel  4 , the worm wheel  4  is displaced back and forth along the stationary spindle. Together with the worm wheel  4 , the gear housing  1  accommodating the worm wheel  4  is displaced back and forth. The worm wheel  4  here is driven by a worm  3  provided on the top and a drive shaft, which is connected to the drive shaft mount  32  of the worm  3 . 
     For inserting the worm wheel  4 , the gear housing  1  comprises worm wheel spaces  17  beneath the upper element  10  and beneath the worm space  12 . The worm wheel space  17  may be bordered by two or more mutually opposed closed walls or preferably by the four legs  11 . Two mutually adjacent legs  11 , respectively, thus form a second side wall  18 . Each of these two mutually opposed second side walls  18  includes a worm wheel bearing  19 . The diameter of this worm wheel bearing  19  is equal to or larger than the outside diameter d 1  of the worm wheel shaft  40 , so that the worm wheel shaft  40  is supported rotatably about the worm wheel axis Y in the two worm wheel bearings  19 . 
     A worm wheel bearing access opening  20  is provided in the two second side walls  18  for inserting the worm wheel  4  in the worm wheel bearing  19 . The worm wheel bearing access openings  20  extend from the two worm wheel bearings  19  to the bottom of the two second side walls  18  or to the bottom of the gear housing  1 , so that the worm wheel  4  can be inserted from beneath with the worm wheel shaft  40  through the worm wheel bearing access opening  20  upwards into the worm wheel bearing  19 . 
     So as to support the worm wheel  4  and/or the worm wheel shaft  40  downward in the worm wheel bearings  19 , a distance d 2  of the walls in the worm wheel bearing access openings  20  is preferably slightly smaller than the outside diameter of the worm wheel shaft  40 . The wall material of the worm wheel bearing access openings  20  and/or the material of the worm wheel shafts  40  are elastic such that the worm wheel shaft  40  can be inserted in the worm wheel bearings  19  from beneath through the worm wheel bearing access openings  20  and is supported securely towards the bottom by the walls after reaching the worm wheel bearings  19 . To facilitate the insertion of the worm wheel shaft  40  in the worm wheel bearing access openings  20 , the openings have a wall tapered towards the bottom and the outside as insertion taper  21 . 
     Additionally or alternatively, a housing cover in the form of a housing closure element  2  may be inserted in the gear housing  1  from beneath. The housing closure element  2  then closes off the worm wheel space  17 , which is otherwise open towards the bottom. The upper wall of the housing closure element  2  is preferably rounded such that the worm wheel space  17  forms a sufficiently large space for the worm wheel teeth  41  and so that the two ends of the worm wheel shaft  40  are supported on correspondingly shaped bearing surfaces  22 . So as to fix the housing closure element  2  in the gear housing  1 , a prior art detent closure comprising, for example, corresponding detent elements may be provided on the legs  11  of the gear housing  1 . It is particularly preferred, however, if bolt recesses  23  for accommodating fastening bolts  24  are provided, wherein the bolt recesses  23  in the form of through-bores extend through the legs  11  as well as a lateral wall  25  of the housing closure element  2 . The width of the lateral walls  25  preferably corresponds to the distance d 2  of the walls of the worm wheel bearing access openings  20  so that the worm wheel space  17  is sealed towards the second side walls  18  after the worm wheel  4  has been inserted. The worm wheel axis Y extends particularly in a direction perpendicular to the worm axis X, as is known from prior art. 
     According to an alternative embodiment, a worm wheel  4  with a worm wheel shaft  40  may also be used in place of a worm wheel  4  with integrated spindle nut  42 , wherein then in addition to the worm wheel teeth  41  worm teeth are configured on the worm wheel shaft  40 . The worm teeth then serve the meshing with the teeth of a toothed rack, which is disposed in a stationary manner, for example in a rail attached on the vehicle bottom, in order to displace the gear housing  1  back and forth along the toothed rack. In this case, the bottom of the gear housing  1  is open to the bottom in order to allow engagement of the toothed rack, wherein such a toothed rack may extend through the worm wheel bearing access openings  20 . In particular, such a toothed rack may also serve as abutment for the worm wheel  4 , so that the constriction of the distance of the legs  11  or the walls of the worm wheel bearing access openings  20  need not be smaller than the diameter d 1  of the worm wheel shaft  40 . 
     It is also possible to implement a plurality of further embodiments of the gear housing  1 . The gear housing  1  may be formed, for example, by a substantially cuboid housing with an open floor wall and four worm bearing or worm wheel bearing access openings  15 ,  20  extending through the side walls from the floor wall, which openings are directed upward to the respective worm bearing  14  or worm wheel bearing  19 . 
     Instead of using elastic wall materials, it is also conceivable to configure elastic transition regions, particularly at the height of the worm wheel bearings  19  and/or the worm bearings  14 , in order to temporarily widen the downward extending lateral walls of the worm wheel bearing access openings  20  and/or of the worm bearing access openings  15  for pushing through the worm wheel shaft  40  and/or the worm shaft  30 . 
     Plastic material is particularly preferred for the gear housing  1 , the worm  3  and the worm wheel  4  because it allows simple manufacturing using an injection molding process. In principle, however, also other materials can be used, particularly metal, to produce such gears. 
     A gear of this configuration comprising such a gear housing  1  with worm  3  and worm wheel  4  is used, for example, in an arrangement according to  FIG. 3  in place of the gear  6  depicted there. The spindle  62  is guided through the spindle nut  42 . The drive shaft  67  of the drive mechanism  66  is connected to the drive shaft mount  32  of the worm shaft  30  of the worm  3 . Driving the drive shaft  67  by means of the drive mechanism  66  thus results in a rotation of the worm  3 , which in turn results in a corresponding rotation of the worm wheel  4 . As a result of the subsequent rotation of the spindle nut  42 , the worm wheel  4 , and via the support thereof in the worm wheel bearing  19  also the gear housing  1 , are displaced back and forth along the stationary spindle  62 . Together with the gear housing  1 , the upper rail  61 , which forms one of the adjustable elements, is displaced via the mount  63  in relation to the lower rail  60 , which forms the other adjustable element, so that a seat attached to the upper rail  61  is displaced forward or backward relative to a vehicle bottom. 
     According to an alternative embodiment, the worm wheel  4  may also be disposed as an upper tooth element in the gear housing  1  above the worm  3 . 
     Particularly with an arrangement of the worm wheel  4  as the lower tooth element in the gear housing  1  with the penetrating spindle  62 , a support for the worm wheel shaft  40  that is closed toward the bottom may be eliminated if the spindle  62  retains the worm wheel  4 , and via the worm wheel  4  optionally retains also the worm  3 , relative to the gear housing  1  in the corresponding bearings  14 ,  19 . 
     LIST OF REFERENCE NUMERALS 
     
         
           1  Gear Housing 
           10  Upper Element of  1   
           11  Legs/Bar-Shaped Extensions of  1   
           12  Worm Space 
           13  First Side Walls of  1   
           14  Worm Bearing 
           15  Worm Bearing Access Openings 
           16  Retaining Bar in  15   
           17  Worm Wheel Space 
           18  Second Side Walls of  1   
           19  Worm Wheel Bearing 
           20  Worm Wheel Bearing Access Openings 
           21  Insertion Taper of  20   
           2  Housing Closure Element/Cover 
           22  Bearing in  2  for  40   
           23  Bolt Recesses 
           24  Fastening Bolt 
           3  Worm 
           30  Worm Shaft 
           31  Worm Teeth 
           32  Drive Shaft Mount in  30   
         X Worm Axis 
           4  Worm Wheel 
           40  Worm Wheel Shaft 
           41  Worm Wheel Teeth 
           42  Spindle Nut 
         Y Worm Wheel Axis 
         d 1  Diameter of  40   
         d 2  Distance of opposite walls of the worm wheel bearing access openings  20   
         d 3  Diameter of  30   
         d 4  Distance of opposite walls of the worm bearing access openings  15