Abstract:
A vehicle seat lumbar support adjustment device includes an actuator operatively connected to a cable which extends across the seatback. A compressible plastic support structure is positioned between the cable and a cushion layer, and movable toward the cushion layer by actuation of the cable in order to adjust lumbar support for a seat occupant. Preferably, the compressible plastic support structure includes an integrally molded spring component positioned between opposing walls of the support structure.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. provisional application Ser. No. 60/214,618, filed Jun. 28, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a vehicle seat lumbar support system including a compressible plastic support structure which includes an integrally molded spring, and a cable operative to adjust the compressed position of the plastic support structure against a lower seatback cushion for lumbar adjustment.  
           [0004]    2. Background Art  
           [0005]    For ergonomic and therapeutic reasons, it is desirable to provide adjustable support to the lower lumbar region of a person&#39;s back when seated for long periods of time. As automobile driving often entails long-seated periods with only limited movement, lumbar support mechanisms are a welcome addition to many automobile seat assemblies. The lumbar support mechanisms must be adjustable in view of varying body sizes and shapes of automobile drivers and passengers, as well as the desire to alter one&#39;s seating conditions from time-to-time.  
           [0006]    Adjustable lumbar support systems typically provide a mechanism or inflatable device located in the seatback adjacent to the lumbar region of the passenger&#39;s back. This allows the passenger to adjust the extent to which a lumbar support member protrudes from within the seatback. As a passenger begins to experience fatigue, adjusting the position of the lumbar support member can reduce fatigue and increase customer satisfaction.  
           [0007]    The prior art has advanced many types of adjustable lumbar support mechanisms for the automobile seat environment, including both manually adjusted and power adjusted units. A wide variety of such systems are available. These systems often suffer from one or more problems, such as complexity of construction and consequent expense. Less complicated and less expensive systems may be less effective in operation.  
           [0008]    While nearly all prior art lumbar support mechanisms function satisfactorily, there remains the ever-present desire to further reduce both cost and weight, while maintaining and/or increasing durability, functionality, and assembly.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention provides a vehicle seat lumbar support adjustment device which includes a compressible plastic support structure with an integrally molded spring.  
           [0010]    More specifically, the present invention provides a vehicle seat lumbar support adjustment device including an actuator operatively connected to a cable which extends across a seatback. A compressible plastic support structure is positioned between the cable and a cushion layer, and movable toward the cushion layer by tensioning of the cable in order to adjust lumbar support for a seat occupant. Preferably, the compressible plastic support structure includes an integrally molded spring component positioned between opposing walls of the support structure.  
           [0011]    The integrally molded spring component is formed by intersecting walls of the support structure. The intersecting walls cross over each other to form at least one generally X-shaped configuration when viewed in horizontal cross-section.  
           [0012]    Another aspect of the invention provides a vehicle seat occupant protection system including a compressible plastic support structure positioned behind a cushion layer in a seatback. The plastic support structure includes an integrally molded spring component positioned between opposing walls of the support structure. The plastic support structure is sufficiently compressible to provide a catcher&#39;s mitt-type occupant protection system at low vehicle speeds wherein, upon rear impact, the occupant penetrates deeply into the seatback by compressing the plastic support structure during impact so that the occupant is retained in the seated position.  
           [0013]    Accordingly, an object of the invention is to provide a vehicle seat lumbar support adjustment device including a flexible, compressible plastic support structure which is adjustably compressed against a cushion layer by an actuator-adjusted cable extending across the seatback.  
           [0014]    Another object of the invention is to provide a lumbar support adjustment device in which cost and weight are reduced while maintaining and/or increasing durability, functionality and assembly.  
           [0015]    The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 shows a perspective view of a drive motor in accordance with the present invention;  
         [0017]    [0017]FIG. 2 shows a cut-away perspective view of the drive motor of FIG. 1;  
         [0018]    [0018]FIG. 3 shows an exploded perspective view of the drive motor of FIG. 1;  
         [0019]    [0019]FIG. 4 shows a horizontal cross-sectional view of the lumbar support mechanism of the present invention, with an adjusted position shown in phantom;  
         [0020]    [0020]FIG. 5 shows a perspective view of a vehicle seatback incorporating a lumbar support mechanism in accordance with the embodiment of FIG. 4;  
         [0021]    [0021]FIG. 6 shows an enlarged perspective view of an actuator and lumbar support member taken from FIG. 5;  
         [0022]    [0022]FIG. 7 shows a perspective rear view of a compressible plastic lumbar support positioned in a seatback corresponding with FIG. 5;  
         [0023]    [0023]FIG. 8 shows a plan view of a lumbar support mechanism in accordance with a slightly modified alternative embodiment of the invention;  
         [0024]    [0024]FIG. 9 shows a cross-sectional view taken through FIG. 8;  
         [0025]    [0025]FIG. 10 shows a longitudinal cross-sectional view of a manual lumbar adjustment mechanism in accordance with a further embodiment of the invention;  
         [0026]    [0026]FIG. 11 shows a side view of the manual lumbar mechanism of FIG. 10;  
         [0027]    [0027]FIG. 12 shows an exploded perspective view of the manual lumbar mechanism of FIG. 10;  
         [0028]    [0028]FIG. 13 shows a perspective, assembled view of the lumbar mechanism of FIG. 12; and  
         [0029]    [0029]FIG. 14 shows a reverse perspective view of the lumbar mechanism of FIG. 13. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]    FIGS.  1 - 3  show a drive motor (or actuator) assembly for actuation of a lumbar support device in a vehicle seat assembly. In particular, this aspect of the present invention provides a very compact assembly by encapsulating a motor within a screw housing.  
         [0031]    As shown in FIGS. 1 and 2, the lumbar drive mechanism (or actuator)  10  includes a housing  12  which encloses a rotatable drive screw  14  which is operatively associated with a movable nut  16 . The movable nut  16  is internally threaded for engagement with the threads of the drive screw  14 . A drive motor  18  is positioned within the drive screw  14  for rotatably driving the drive screw  14  to move the movable nut  16  along the internal cavity  20  formed by the housing  12 .  
         [0032]    The nut  16  includes a shoulder screw  22  which is operatively associated with a slot  24  of a pivotable brace  26 . The pivotable brace  26  is operative to pivot about the pivot joint  28  when pivoted by the moving nut  16  to actuate a lumbar support mechanism. A lid  30  encloses the end of the housing  12 .  
         [0033]    This assembly is easy to fit and adapt to an existing seat back frame and is very compact, particularly because the motor  18  is encapsulated within the screw  14  within the housing  12 .  
         [0034]    [0034]FIG. 4 shows the lumbar drive mechanism  10  of FIGS.  1 - 3  implemented on a vehicle seat assembly  35  for adjusting a lumbar support device  36  in accordance with a preferred embodiment of the invention. The lumbar support device  36  is shown in various views in FIGS.  4 - 9 , with FIGS. 8 and 9 illustrating a slightly modified alternative embodiment. The lumbar support device  36  includes an adjustable cable  38  which presses a plastic support structure  40  against the foam  42  on the backside of the squab  43  for lumbar adjustment. A first end  44  of the cable  38  is fixed to the back frame  46 , and a second end  48  of the cable  38  is connected to the pivoting brace  26  of the lumbar drive mechanism  10 .  
         [0035]    When the drive mechanism  10  is actuated from the position shown in solid lines in FIG. 4 to the position shown in phantom lines in FIG. 4, the cable  38  is pulled tight against the plastic support structure  40  to force the plastic support structure  40  and the foam  42  forward toward the occupant to support the lumbar region of the seat occupant&#39;s back.  
         [0036]    The plastic support structure  40  is provided with a Rhomboid-like shape in plan view having an integral spring component  50  to facilitate compression and expansion of the plastic support structure  40 . As shown in FIG. 4, the spring structure  50  is formed between opposing outer walls  51 , 53  which intersect with inner walls  55 , 57  to form generally X-shaped configurations  59 , 61  when viewed in horizontal cross-section. In other words, the outer walls  51 , 53  form a large, generally oval shape in horizontal cross-section, and the inner walls  55 , 57  form a smaller, generally oval shape in horizontal cross-section, with side walls of the oval shapes intersecting at the X-shape locations  59 , 61  to form the integral spring structure. FIG. 9 shows slightly modified oval-like shapes for the plastic structure  40 ′, including the spring structure  50 ′.  
         [0037]    These spring structures provide even pressure distribution across the foam  42 , enhance lumbar cushioning, and provide protection from rear impact and whiplash by enhancing occupant retention in a rear impact (i.e., as in the “catcher&#39;s mitt” concept used in seat back designs for retaining an occupant against the seat back to prevent the occupant from riding up along the seat back during a rear impact). This added occupant retention is achieved because the occupant may protrude further (i.e. recess further) into the lower part of the seat by compression of the plastic support structure  40  so that the lower part of the seat back actually acts as a catcher&#39;s mitt-type configuration to retain the occupant in the seated position against the seat back during a rear impact.  
         [0038]    Referring to FIGS. 5 and 8, metal wires  52 , 54  and  52 ′,  54 ′ are provided as extra whiplash protection. These wires  52 , 54  may be bent during impact by impact force of a body against the plastic support structure  40  for allowing deep penetration of the lower back into the seat for enhanced catcher&#39;s mitt effect, and the cold working or bending of the wires  52 , 54  helps to dissipate energy of the occupant. As shown in FIG. 5, the plastic support structure  40  includes a plurality of holes  56  for reduced weight. Also, an upper plastic support structure  58  is supported by a strap  60  which extends between opposing legs of the seat back frame  46 .  
         [0039]    Turning to FIGS.  10 - 14 , another aspect of the invention provides a manual lumbar actuation mechanism  70  to replace the power mechanism  10  shown in FIGS.  1 - 6 . As shown in FIGS.  10 - 14 , the manual lumbar actuation mechanism  70  includes a housing  72  which encloses a rotatable screw  74  which drives a nut  76  for actuating a lumbar mechanism. The nut  76  includes a shoulder bolt  78  which engages in a slot  80  of a pivoting brace  82 . The brace  82  pivots about a pivot rod  84 , which cooperates with a hole  86  in the housing  72 . The pivoting brace  82  may be connected to a cable, such as cable  38  shown in FIG. 6, for actuating a lumbar mechanism.  
         [0040]    The manual lumbar actuation mechanism also includes a handle  88  which rotatably drives a gear rack  90 , which engages the gear  92  on the screw  74  for selectively rotating the screw. A torsional spring  94  is provided for assisting manual rotation of the handle  88  for lumbar actuation. The compressed foam (such as foam  42  shown in FIG. 6) provides an assist force for deactivating the mechanism  70 . Once the handle  88  has been adjusted to the desired position, the friction forces between the threads of the screw  74  and the threads of the nut  76  hold the lumbar mechanism in the selected position.  
         [0041]    A primary advantage of this structure is that the additional moment arm provided by the lever  88  and the moment arm between the pivot axis and gears of the rack  90  reduce the force required for lumbar adjustment by a seated occupant. Also, the torsional spring  94  reduces the force required for adjustment.  
         [0042]    While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the various aspects of the invention without departing from the spirit and scope of the invention as defined in the appended claims.