Abstract:
The invention relates to a seat adjuster ( 100 ) especially for a seat ( 105 ) in a motor vehicle, comprising an adjusting element ( 115 ), an electric adjusting device ( 110 ) and a transmission device ( 120 ) for transmitting adjusting forces between the electric adjusting device and the adjusting element, the transmission device comprising a transmission element ( 320 ) for transmitting adjusting forces and the transmission element being flexible at a right angle to the direction of the adjusting forces.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    An adjustable seat for an occupant of a motor vehicle may be manually operated or motor-operated. Aside from the usual adjustment functions for seat inclination and sliding the seat along the direction of travel, it is additionally possible for example for a headrest, an armrest, a lumbar support, a seat height or seat inclination position or other movable elements of the seat to be adjusted. Furthermore, such a seat may comprise seat elements which, if the motor vehicle is involved in a severe accident, are moved automatically and if appropriate in an accelerated manner into a position in which they serve to provide improved support of the occupant of the motor vehicle. 
         [0002]    Drives for actuating the adjustable elements of the seat may be of electrical construction, of pneumatic construction, of pyrotechnic construction or of a construction based on a preloaded spring. As the number of adjustable seat elements and drives for the seat elements increases, the weight, complexity and manufacturing costs of the seat also increase. 
         [0003]    EP 1 726 475 A1 presents a device for the motor-powered actuation of a side cheek of a seat of a motor vehicle as a function of a signal which indicates the risk of an accident of the motor vehicle. 
         [0004]    EP 1 633 606 B1 (WO 2004/103779 A1) provides an occupant protection system for motor vehicles, wherein at least one actuator with two speed stages acts on a seat adjuster. A first, slow speed stage provides comfort adjustment facility of the seat, whereas a second, fast speed stage is used for a rapid adjustment in the event of an impending accident. Actuators which are used may comprise electric motors, a pneumatic system or preloaded mechanical springs. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an object of the invention to specify an improved seat adjuster for a seat in a motor vehicle. 
         [0006]    According to the invention, a seat adjuster, in particular for a seat in a motor vehicle, comprises an adjusting element, a linear electrical adjusting device and a transmission device for transmitting adjustment forces between the electrical adjusting device and the adjusting element, wherein the transmission device has a transmission element for transmitting adjustment forces, said transmission element being flexible transversely with respect to the direction of the adjustment forces. 
         [0007]    The adjustment element may for example change a position of the seat in the motor vehicle or adjust a restraint element for supporting a person in the seat. As a result of the transmission of adjustment forces by means of a flexible and in particular bendable transmission element, a position of the electrical adjusting device can be selected independently of the position of the adjusting element. This provides an additional degree of design freedom in the configuration and mounting of the electrical adjusting device and of the adjusting element. Furthermore, a mass distribution of the seat adjuster or of the seat may be optimized, for example with regard to a minimized risk of injury in the event of an accident. Furthermore, the electrical adjusting device may be mounted so as to be easily accessible for assembly and maintenance work. It is also possible, through the provision of a flexible transmission device, for the adjusting element and the electrical adjusting device to be mounted on separate elements of the seat which can be adjusted in terms of their position relative to one another, for example by means of a further adjusting device. 
         [0008]    The electrical adjusting device preferably comprises a rotatable drive element which engages with a rising spiral. In this way, the linear adjustment may be provided by means of an electric motor. Furthermore, the rising spiral may be designed so as to form, together with the rotatable drive element, an overload clutch which slips if a predefined adjustment force is exceeded, thus minimizing damage to the seat adjuster and/or injury to a vehicle occupant in the region of the seat. Furthermore, an alignment of the adjusting element can be realized by rotation of the rising spiral relative to the drive element. A play-free articulated connection of the adjusting element can thus be attained. 
         [0009]    To the transmission element there may also be connected a further rising spiral which engages with a threaded element of the adjusting element. The two rising spirals may be arranged on opposite ends of the adjusting element and may be coiled in the same direction or in opposite directions. If both rising spirals are coiled in the same direction, then during the course of an alignment, a position of the transmission element relative to the adjusting element and relative to the adjusting element can be adjusted. If the two rising spirals are coiled in opposite directions, the positions of the adjusting element and of the electrical adjusting device relative to one another can be varied by rotation of the adjusting element. 
         [0010]    The further rising spiral in the region of the adjusting element may be connected to a transmission element, wherein in all operating positions of the seat adjuster, the transmission element is arranged in the region of an axial end of a sheath of the transmission element. In this way, during the actuation of the seat adjuster, no portion of the rising spiral passes the axial end of the sheath, as a result of which rattling or clattering noises can be prevented. The transmission element may be of generally cylindrical form and in particular of generally straight cylindrical form, such that no channels or steps which run transversely with respect to the actuating device pass the axial end of the sheath. It is possible for the transmission element to be formed, correspondingly to the sheath, with a non-circular cross section, for example an elliptical or polygonal cross section, such that twist prevention can also be realized in addition to noise reduction. 
         [0011]    The seat adjuster may comprise two cable pull portions which are actuated in antiparallel fashion by the electrical adjusting element. Through the use of cable pull portions, it is possible for adjustment forces to be transmitted between the adjusting device and the adjusting element along radii so small that a transmission by means of a Bowden cable would generate disadvantageously high friction forces. If appropriate, a diverting roller may be provided for guidance and diversion of one of the cable pull portions. An embodiment of the seat adjuster with cable pull portions may have an advantageously reduced mass. 
         [0012]    In one embodiment, the two cable pull portions are part of a single-piece cable pull. In this way, it can be made easier for the cable pull portions to be mounted and exchanged. A non-positive connection in the region of the adjusting element may be realized by means of clamping, as a result of which the adjusting element can be aligned relative to the cable pull portions. 
         [0013]    It is possible for at least one further adjusting element and one further transmission device for transmitting adjustment forces between the electrical adjusting device and the further adjusting element to be provided. In this way, it is possible for multiple adjusting elements to be actuated by means of the same adjusting device, as a result of which a complexity of the seat adjustment can be minimized and production costs can be saved. The two adjusting elements may be actuated in opposite directions by the electrical adjusting device. In this way, it is advantageously possible for symmetrical adjusting elements of the seat to be actuated in opposite directions by a single adjusting device. 
         [0014]    A sensor for determining an adjustment position may be arranged in the region of an end surface of one of the rising spirals. For example, it is possible in this way for a limit switch of the adjusting device to be of functionally reliable and space-saving form and if appropriate integrated with the adjusting device or the adjusting element. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The invention will now be explained in more detail with reference to the appended figures, in which: 
           [0016]      FIG. 1  shows a seat adjuster on a seat in a motor vehicle; 
           [0017]      FIG. 2  shows the electrical adjusting device of the seat adjuster from  FIG. 1 ; 
           [0018]      FIG. 3  shows a longitudinal section through the seat adjuster from  FIG. 1 ; and 
           [0019]      FIG. 4  shows a schematic illustration of a variant of the seat adjuster of  FIGS. 1 and 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  shows a seat adjuster  100  in a seat  105  in a motor vehicle. An electric adjusting device  110  is arranged between two adjusting elements  115  of mirror-symmetrical construction. Two transmission devices  120  transmit adjusting forces between the electrical adjusting device  110  and the two adjusting elements  115 . The illustrated adjusting elements are for example side supports which are arranged on the right and on the left in the region of a backrest of the seat. If the two adjusting elements  115  are deployed, that is to say folded inward in the illustration, they provide additional side support to the left and to the right for a vehicle occupant sitting on the seat. The deployment may be realized for example for reasons of comfort, owing to expected high cornering speeds as a result of sporty driving, or during the course of preparation for an expected collision of the motor vehicle against an obstruction. An adjustment speed of the electrical adjusting device  110  may be realized in user-controlled form or automatically in different speed stages. 
         [0021]    The adjusting elements  115  are cushioned and covered by a lining of the seat, such that the adjusting elements  115  in the seat are not readily visible. The electric adjusting device  110  may be fastened to the seat  105  or, in another embodiment, may be connected to the motor vehicle. In one embodiment, the electrical adjusting device  110  is situated in the region of a seat surface of the seat, such that the transmission devices  120  transmit adjustment forces between the electrical adjusting device  110  and the adjusting elements  115  in the case of different angles having been set between the backrest and the seat surface. 
         [0022]      FIG. 2  shows the adjusting device  110  of the seat adjuster  100  from  FIG. 1 . An electric motor  205  is flange-mounted axially on a gearbox  210 . The gearbox  210  may be for example a spur gear mechanism or a planetary gear set. The gearbox  210  is connected to a drive output housing  215  through which two parallel-running rising spirals  220  extend. Between the rising spirals  220  there is situated a drive output gearwheel  225  which engages into both rising spirals  220 . Within the drive output housing  215  there is situated an angular gear, which is not visible in the illustration of  FIG. 2 , for converting a rotational movement provided by the gearbox  210  into a rotational movement, running perpendicular thereto, of the drive output gearwheel  225 . The two rising spirals  220 , in the region of engagement with the drive output gearwheel  225 , are pressed in the radial direction against the drive output gearwheel  225  by means of a respectively associated spring  230 . Each spring  230  is assigned an adjustment screw  235  which runs through the drive output housing  215 , wherein the two adjusting screws  235  are situated opposite one another with respect to the drive output gearwheel  225 . Through rotation of the adjusting screws  235 , a pressing force of the associated rising spiral  220  against the drive output gearwheel can be adjusted. 
         [0023]    If the electric motor  205  is electrically activated, it moves the drive output gearwheel  225  via the gearbox  210 , and moves the rising spirals  220  in opposite directions to the left and to the right. In the process, thread flights on the rising spirals  220  protrude individually into tooth spaces between teeth of the drive output gearwheel  225  and ensure a reliable non-positive connection. The conversion of the rotational movement of the gearwheel  225  into linear movements of the rising spirals  220  exhibits self-locking, that is to say a force acting axially on a rising spiral  220  cannot set the drive gearwheel  225  in rotation. 
         [0024]    However, if the axial force acting on the rising spiral  220  exceeds a force predetermined by the spring  230  in conjunction with the adjusting screw  235  assigned thereto, the rising spiral  220  is lifted from the drive output gearwheel  225  in the radial direction, such that the engagement between the rising spiral  220  and the drive output gearwheel  225  is eliminated and the rising spiral  220  can be moved in the axial direction. If the axial movement falls below a force predetermined by the spring  230  in conjunction with the adjusting screw  235  assigned thereto, the rising spiral  220  engages into the drive output gearwheel  225  in the radial direction again such that the axial movement of the rising spiral  220  is blocked. To permit the displacement movement of the rising spiral  220  in the radial direction, the rising spiral  220  may be produced from an elastic material, for example plastic. Furthermore, the rising spirals may have rounded spiral flanks. If necessary, different forces beyond which the engagement of the respective rising spiral  220  with the drive output gearwheel  225  is released may be set by means of the two adjusting screws  235  for the two rising spirals  220 . 
         [0025]    The drive output housing  215  comprises four threaded sleeves  240  through which the rising spirals  220  run at their points of entry and exit into and out of the drive output housing  215 . The threaded sleeves  240  are provided for the fastening of sheaths of Bowden cables which transmit the movement of the rising spirals  220 . 
         [0026]      FIG. 3  shows a longitudinal section through the seat adjuster  100  from  FIG. 1 , wherein in order to provide a clearer illustration, only selected elements are shown. As explained above with reference to  FIG. 2 , the left-hand rising spiral  220  is pressed in the radial direction against the drive output gearwheel  225  by means of the spring  230  and the adjusting screw  23 . In the illustrated embodiment, for the guidance of the left-hand rising spiral  220 , a sliding block  305  is arranged between the spring  230  and the left-hand rising spiral  220 . The teeth of the drive output gearwheel  225  engage with thread flights of the left-hand rising spiral  220 , such that a rotational movement of the drive output gearwheel  225  is converted into a linear movement of the left-hand rising spiral  220 . In the region of a left-hand axial end surface of the left-hand rising spiral  220  there is arranged a limit switch  310  by means of which it is detected when the left-hand rising spiral  220  has reached a left-hand end position. 
         [0027]    The transmission device  120  transmits the linear movement of the left-hand rising spiral  220  to a right-hand rising spiral  220 . The right-hand rising spiral  220  engages with an adjusting nut  315  which transmits an axial movement of the right-hand rising spiral  220  to the adjusting element  115  from  FIG. 1 . 
         [0028]    The transmission device  120  comprises a transmission element  320  and a sheath  325 , of which substantially only end portions are shown in  FIG. 3 . The transmission element  320  may be for example a wire cable by means of which torsional, tensile and thrust forces can be transmitted between the left-hand and right-hand rising spirals  220 . The sheath  325 , like the transmission element  320 , is flexible transversely with respect to a direction of transmission of adjustment forces, for example upward and downward in the illustration of  FIG. 3 , but cannot be compressed or stretched significantly in the axial direction. The transmission device  120  may therefore be laid along a curved path without the transmission of adjustment forces being significantly impaired by the bending. A minimum bend radius is dependent here primarily on materials of the transmission element  320  and of the sheath  325  and on the inner and outer diameters thereof. 
         [0029]    At its left-hand axial end, the sheath  325  is connected to one of the threaded sleeves from  FIG. 2 . It is ensured in this way that, in said region, the left-hand rising spiral  220  and the sheath  325  run coaxially with respect to one another so as to maintain a radial minimum spacing with respect to one another, such that no clattering or rattling noises are generated during an axial movement of the rising spiral  220  into and out of the sheath  325 . A left-hand thrust rod  330  connects the rising spiral  220  to the transmission element  320 , wherein the left-hand thrust rod  330  always runs within the sheath  325 . 
         [0030]    A corresponding threaded sleeve  240  may be provided at a right-hand axial end of the sheath  325 . In the embodiment illustrated in  FIG. 3 , to prevent rattling or clattering noises in the region of the right-hand end of the sheath  325 , a right-hand thrust rod  330  is arranged between the transmission element  320  and the rising spiral  220 . The right-hand thrust rod  330  is of such a length that, between a left-hand and a right-hand end position of the rising spiral  220 , the right-hand rising spiral  220  does not protrude or slide out into the right-hand axial end of the sheath  325 . 
         [0031]    The left-hand and the right-hand rising spirals  220  are coiled in opposite directions. Since the transmission element  320  also transmits torsional forces, an assembly composed of the left-hand rising spiral, the left-hand thrust rod  330 , the transmission element  320 , the right-hand thrust rod  330  and the right-hand rising spiral  220  can be rotated conjointly. Here, depending on the direction of rotation, a spacing of the drive output gearwheel  225  from the adjusting nut  315  along the transmission device  120  is increased or decreased. As a result, a position of the adjusting element  115  can be adjusted independently of a rotation of the drive output gearwheel  225 . Furthermore, in the case of a mirror-symmetrical articulated connection of two adjusting elements  115  as shown in  FIGS. 1 and 2 , a relative position of the adjusting elements  115  can be varied by means of the described rotation. 
         [0032]    In an alternative embodiment which is not shown, the left-hand rising spiral  120  and the right-hand rising spiral  220  are, in  FIG. 3 , coiled in the same directions. In this case, the described rotation does not result in a change of the relative position of the adjusting element  115  relative to the drive output gearwheel  225 ; instead, the assembly composed of the left-hand rising spiral  120 , the left-hand thrust rod  330 ; the transmission element  320 , the right-hand thrust rod  330  and the right-hand rising spiral  220  can be moved to the left or the right, depending on the direction of rotation. In this way, it is for example possible for a triggering position of the limit switch  310  to be reached. 
         [0033]    During operation of the seat adjuster  100 , the described rotation may be prevented for example through the provision of a lock nut on the adjusting nut  315  on the right-hand rising spiral  220 . If a transmission of torsional forces between the left-hand and right-hand rising spirals  220  is undesired, then a swivel element (not illustrated) may be arranged between one of the two rising spirals  220  and the associated thrust rod  330 . Each of the rising spirals  220  may then be rotated independently of the other rising spiral  220 , such that on the whole, both a position of the rising spiral  220  relative to the limit switch  310  and also an alignment of the adjusting element  115  relative to a position of the drive output gearwheel  225  can be adjusted, as discussed above. 
         [0034]    In a further embodiment, in the region of the adjusting nut  315 , an arrangement is used which corresponds to the arrangement composed of the drive output gearwheel  225 , the sliding block  305 , the spring  230  and the adjusting screw  235 . The linear movement of the right-hand rising spiral  220  is thereby converted into a rotational movement, wherein an integrated overload protection means for preventing excessive thrust forces is implemented, as discussed above. The overload protection means in the region of the electrical adjusting device  110  may also be omitted. 
         [0035]      FIG. 4  is a schematic illustration of a variant of the seat adjuster  100  of  FIGS. 1 and 3 . The electrical adjusting device  110  is arranged between the two adjusting elements  115  from  FIG. 1 . The two rising spirals  220  are actuated linearly in antiparallel fashion by the electric adjusting device from  FIGS. 1 and 2 . Portions of a cable pull  405  run in each case between the rising spirals  220  and the adjusting elements  115 . In the region of each adjusting element  115 , the ends of the portions of the cable pull  405  are connected to one another at a knee lever joint  410 , or are formed in one piece with one another and fastened to the knee lever joint  410 . Such an arrangement is conventional for window lifters or sliding roofs of motor vehicles. 
         [0036]    Those portions of the cable pull  405  which are connected to the left-hand adjusting element  115  are connected to the rising spirals  220  in an interchanged manner with respect to those portions of the cable pull  405  which are connected to the right-hand adjusting element  115 , such that in a first direction of actuation of the electrical adjusting device  110 , the two knee lever joints  410  are moved inward and the two adjusting elements  115  are spread out, and in a second direction of actuation of the electric adjusting device  110 , the two knee lever joints  410  are moved outward and the two adjusting elements  115  are folded in. 
         [0037]    The transmission of the linear movement of the rising spirals  220  of the electrical adjusting device  110  by means of the portions of the cable pull  405  to the knee lever joints  410  of the adjusting elements  115  may be guided, analogously to the above description with regard to  FIG. 3 , by means of a Bowden cable or, for example with the omission of a sheath  325  of the portions of the cable pull  405 , by means of cable rollers (not illustrated). In a further embodiment of the device  100  as per  FIG. 4 , the rising spirals  220  may be omitted; a facility for adjustment of the knee lever joint  410  without actuation of the adjusting device  110 , as described above with regard to  FIG. 3 , is then not provided.