Abstract:
In a longitudinal seat adjuster ( 3 ) for a vehicle seat, in particular a motor vehicle seat, with at least one seat rail assembly ( 5 ) including at least two seat rails ( 11   a,    12, 13   b ) that define an installation space ( 15 ) and are powered by a motor to be relocatable in relative position to one another, at least a first spindle ( 20 ) and a first spindle nut ( 21 ) are located within the installation space ( 15 ) and interact with one another, and the installation space ( 15 ) allows room for a second spindle ( 30 ) and a second spindle nut ( 31 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     The present application claims priority to DE 10 2004 010 489.1, which was filed on Mar. 4, 2004, and is incorporated herein by reference.  
       TECHNICAL FIELD  
       [0002]     The present invention relates to a longitudinal adjuster for a vehicle seat and, more specifically, to a longitudinal adjuster including a seat rail assembly with elongate seat rails mounted for there being relative longitudinal movement therebetween, with the seat rails cooperating with one another to define an installation space that contains a spindle which interacts with a spindle nut for causing the relative movement between the seat rails.  
       BACKGROUND OF THE INVENTION  
       [0003]     In a longitudinal seat adjuster of the kind mentioned in the above Technical Field section, the installation space in the seat rail assembly substantially solely contains the single spindle, the single spindle nut, and other gearbox parts. In view of avoiding structural damage, and the needed longitudinal locking force, the structural components are appropriately dimensioned in order to meet the various load requirements.  
       BRIEF SUMMARY OF SOME ASPECTS OF THE INVENTION  
       [0004]     In accordance with one aspect of the present invention, a longitudinal adjuster for a vehicle seat, in particular a motor vehicle seat, has at least one seat rail assembly with elongate seat rails mounted for there being relative longitudinal movement therebetween, and the seat rails cooperate with one another to define an installation space. In accordance with this aspect, the adjuster further includes at least a first spindle and at least a first spindle nut that are within the installation space. The first spindle and the first spindle nut are mounted so that they are meshed with one another for there being relative rotation therebetween, and so that the relative rotation between them at least partially causes the relative longitudinal movement between the seat rails. Further in accordance with this aspect, the installation space is configured in a predetermined manner to be capable of having a second spindle and a second spindle nut within the installation space and meshed together.  
         [0005]     Due to the fact that the installation space provides space for a second spindle and a second spindle nut, a modular seat rail assembly is provided which can be adjusted to the required longitudinal locking force via selecting the number of spindles. In case of low load requirements, only one spindle is used. In case of higher load requirements, two spindles are used. The first spindle has the function of longitudinal adjustment. The second spindle increases the longitudinal locking force. That is, in accordance with one aspect of the present invention, the seat rails are designed for the use of one spindle as well as two spindles. In accordance with one aspect of the present invention, the use of one or two spindles does not have any effect on the interface/mounting points between the seat rail assembly and the vehicle structure, and likewise it does not have any effect on the interface/mounting points between the seat rail assembly and the vehicle seat structure. That is, in one example, the use of one or two spindles does not have any effect on the outside geometry and outside dimensions of the seat rail assembly. Each vehicle seat can have two of the modular seat rail assemblies mounted thereto, with the modular seat rail assemblies respectively relegated to being proximate the opposite sides of the vehicle seat and being respectively adapted for the anticipated seat belt force. That is, and for example, the seat rail assembly that is mounted to the same side of the seat as the seat belt buckle can have two spindles and respectively associated spindle nuts, whereas the other seat rail assembly can have only one spindle and associated spindle nut.  
         [0006]     For a seat rail assembly with two spindles and spindle nuts, a single drive (e.g., drive motor) can drive both of the spindles or spindle nuts. In view of such a common, at least approximately synchronous drive, the second spindle can be placed parallel to the first spindle and is threaded in the opposite direction as compared to the first spindle (i.e., the substantially simultaneous rotation of the first and second spindle nuts of the same seat rail assembly is in opposite rotational directions). In order for the spindle nuts of the same seat rail assembly to be driven, the seat rail assembly can be provided with a common drive consisting essentially of one worm. The worm engages in the two associated spindle nuts (which can also be referred to as worm gears due to their outer teeth) when two spindle nuts are present. The worm can be powered by a single motor which simultaneously powers the worms of both seat rail assemblies to thereby activate both seat rail assemblies. For a seat rail assembly with the two spindles and the two spindle nuts, it is necessary to allow for clearance between the second spindle nut, on the one hand, and the worm and/or the second spindle, on the other hand, in order to run smoothly and for the purpose of tolerance compensation. Nonetheless, this clearance can be characterized as being optional and thereby nonlimiting with respect to the scope of the present invention. As an alternative to driving the spindle nuts, the spindles could be driven with a common gear assembly.  
         [0007]     In accordance with one aspect of the present invention, the seat rails of a seat rail assembly can be modularly selected from three different groups of seat rails, such as for adjusting the load-handling characteristics with regard to seeking to avoid structural damage. In this regard, a seat rail (e.g., selected from a first group) can partially encompass the next seat rail smaller in size (e.g., selected from a second group) and be partially encompassed by the next seat rail bigger in size (e.g., selected from a third group). Although three groups are specifically mentioned, there could be less or more groups. The generally C-shaped seat rails of a group could come in different moldings; that is, the C-shaped moldings could have different sizes or could have different shapes with respect to the partially encompassing. This can be achieved by producing the seat rails of one group with different molding sizes in the same machinery from metallic (e.g., steel) sheet strips of differing width.  
         [0008]     Further regarding the possibility of modularly constructing the longitudinal adjuster of the present invention, it is also possible for it to be manually driven or driven by a motor.  
         [0009]     Because of its modular construction, such as with regard to spindles and seat rails, the longitudinal adjuster of the present can be used for various purposes. The sides of the seat rail assemblies can be respectively mounted, such as by bolting, to the vehicle structure and the vehicle seat elements, and they can alternatively be mounted by other means, such as by welding.  
         [0010]     Other aspects and advantages of the present invention will become apparent from the following.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The present invention is explained in greater detail below with reference to one exemplary embodiment illustrated in the drawings, in which:  
         [0012]      FIG. 1  shows a cross section through the embodiment, and this drawing is partially schematic, for example in that the round spindles and/or round passageways through the spindle nuts are schematically illustrated as non-circular,  
         [0013]      FIG. 2  schematically illustrates a vehicle seat, and  
         [0014]      FIG. 3  shows various seat rails in different molding sizes. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]     Referring now in greater detail to the drawings, in which like numerals refer to like parts throughout the several views, a vehicle seat  1 , in particular a motor vehicle seat, includes a longitudinal adjuster  3  for the purpose of adjusting the longitudinal seat position. This longitudinal adjuster has a seat rail assembly  5  on both sides of the vehicle seat  1 . Each seat rail assembly  5  is connected to the vehicle structure, on the one hand, and connected the seat element  7  of the vehicle seat  1 , on the other hand.  
         [0016]     Each seat rail assembly  5  includes three molded, elongate seat rails. A first seat rail  11   a  is located on the inside, a second seat rail  12  extends partially around the first seat rail, and a third seat rail  13   b  extends partially around the second seat rail. This arrangement outlines an installation space  15  which is encircled by the combination of the seat rails  11   a,    12 , and  13   b.  The first seat rail  11   a  and the third seat rail  13   b  are fixedly connected to one another. The first and third seat rails  11   a,    13   b  are together movable in the common longitudinal seat rail direction relative to the second seat rail  12 . In order to reduce friction, balls  17  are located between the second seat rail  12  and the third seat rail  13   b.  The side of the second seat rail  12  is connected to structure of the vehicle. The sides of the first and third seat rails  11   a,    13   b  are connected to the seat element  7 .  
         [0017]     Depending on the load requirements, in particular with regard to resisting detachment such as between components of the seat rail assembly  5 , the seat rail assembly  5  can be modularly constructed. For example, a relatively more completely molded first seat rail  11   b  ( FIG. 3 ) can be used in place of the relatively less completely molded first seat rail  11   a,  and/or a relatively less completely molded seat rail  13   a  ( FIG. 3 ) could be used in place of the relatively more completely molded third seat rail  13   b.  The first seat rails  11   a  and  11   b  can be characterized as forming a group, and the third seat rails  13   a  and  13   b  can be characterized as forming another group. The seat rails of one group can be produced in the same machinery from steel sheet strips of different widths. It is also possible to cut them into appropriate sizes after they are produced by the machinery. The desired adjustment (e.g., modularity) could also be achieved by leaving out the first seat rail  11   a/   11   b  or the third seat rail  13   a/   13   b.  A further adjustment could be achieved by placing different amounts and arrangements of balls  17  between the three possible seat rails.  
         [0018]     In order to drive the longitudinal adjuster  3  by way of a motorized drive, each of seat rail assemblies  5 , which are respectively located proximate the sides of the vehicle seat  1 , includes a first spindle  20  inside of the installation space  15  and extending in the longitudinal seat rail direction. For each of the seat rail assemblies  5 , both ends of its spindle  20  are fixedly connected to the second seat rail  12 . Internally threaded, first rotatable spindle nuts  21  are respectively placed on each of the first spindles  20 , so that the internal threads of the first spindle nuts respectively mesh with the external threads of the first spindles. As a result, each first spindle nut  21  can rotatably travel along the respective first spindle  20  and thereby cause the associated second seat rail  12  to travel relative to the associated first and third seat rails  11   a,    13   b.  More specifically in accordance with the exemplary embodiment, while each first spindle nut  21  rotates around its respective first spindle  20 , travel of the first spindle nut  21  in the longitudinal direction relative to the first and third seat rails  11   a,    13   b  is restricted in a conventional manner, so that the associated first spindle  20  and second seat rail  12  travel together in the longitudinal direction relative to the first and third sear rails.  
         [0019]     For each of the seat rail assemblies  5 , external teeth of the first spindle nut  21  (e.g., worm gear) mesh into external threads of a worm  23 . The worm  23  is mounted in a conventional manner so that movement of it in the longitudinal direction relative to the first and third seat rails  11   a,    13   b  is restricted. In accordance with the exemplary embodiment, each worm  23  is turned by a respective shaft  25 , and these shafts are powered by a common motor  27 . That is, a single motor  27  can substantially simultaneously turn the worm  23  of each seat rail assembly  5 .  
         [0020]     The installation space  15  is dimensioned in a way that allows room for a second spindle  30  and a second spindle nut  31 . For example and not for the purpose of narrowing the scope of the present invention, the second spindle  30  and the second spindle nut  31  may be desired (e.g., required) in the installation space  15  proximate the side of the vehicle seat  1  to which the seat belt buckle (not shown) is mounted. For example, for the pair of seat rail assemblies  5  illustrated in  FIG. 1 , the seat belt buckle assembly can be connected to the side of the seat  1  that includes the seat rail assembly  5  with the two spindles  20 ,  30  and the two spindle nuts  21 ,  31 , as opposed to being connected on the side of the seat that includes the seat rail assembly with only one spindle  20  and one spindle nut  21 .  
         [0021]     In accordance with the exemplary embodiment, this second spindle  30  would be positioned parallel to the first spindle  20  and is also fixedly connected to the second seat rail  12 , and the second spindle  30  is threaded in the opposite direction as compared to the first spindle  20 . Internal threads of a second spindle nut  31  mesh with the external threads of the second spindle  30  so that the second spindle nut  31  can rotatably travel along the second spindle  30 . More specifically in accordance with the exemplary embodiment, while the second spindle nut  31  rotates around the second spindle  30 , travel of the second spindle nut  31  in the longitudinal direction relative to the first and third seat rails  11   a,    13   b  is restricted in a conventional manner, and the second spindle  30  and second seat rail  12  travel together in the longitudinal direction relative to the first and third sear rails.  
         [0022]     In accordance with the exemplary embodiment, external teeth of the second spindle nut  31  (e.g., worm gear) mesh with the external threads of the previously mentioned worm  23 , so that the common worm  23  provides a substantially synchronous drive for both spindle nuts  21  and  31 .  
         [0023]     Clearance is provided between the second spindle nut  31 , on the one hand, and the second spindle  30  or the worm  23 , on the other hand, in order to avoid blocking (e.g., jamming of) the motor  27 , in accordance with the exemplary embodiment of the present invention. In accordance with the exemplary embodiment, the system of the first spindle  20  serves the purpose of longitudinal adjustment, whereas the system of the second spindle  30  serves the purpose of increasing the longitudinal locking force. In order to adjust the longitudinal locking force, the seat rail assemblies  5  can be modularly provided with one or two spindles, each in combination with a modular assembly of the seat rails. It will be understood by those skilled in the art that while the present invention has been discussed above with reference to exemplary embodiment(s), various additions, modifications and changes can be made thereto without departing from the spirit and scope of the invention as set forth in the following claims.