Abstract:
An adjustable lumbar support for a seat comprising a pair of parallel lateral rails, wherein each of the lateral rails has a lower end and an upper end, a support panel having a top end and a bottom end, the support panel pivoting at the top end while remaining fixed with respect to the lateral rails, a rail bracket slidably attached to the lateral rails, a spring operatively connected to the rail bracket, wherein the spring biases the rail bracket in a first position, a cable operatively connected to the rail bracket, wherein the cable pulls the bracket from the first position to a second position, and a lift wire pivotably attaching the support panel to the rail bracket.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   None. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to lumbar supports, particularly for use in folding seats of vehicles. 
   2. Related Art 
   Fold-down rear seats are a very popular feature in vehicles. The folding of seats to make cargo space available is preferable to having to remove seats completely. To maximize the amount of cargo space available upon folding of the seats, it is preferable to have the seats fold into a very thin profile form. One way to minimize the folded profile of a seat is to reduce the amount of cushioning in the seat. However, at the same time consumers also want the unfolded seats to be comfortable. Thus there is a balance between maintaining seat comfort versus the ability to fold the seat into the most compact form possible. 
   Further complicating the issue is the consumers&#39; desire to have advanced comfort features such as ergonomic support devices on all of the seats of the vehicle. Many seats, even in the rear passenger positions, contain ergonomic support devices embedded therein to promote passenger comfort. Such devices, for example lumbar supports, typically have three-dimensional forms that support different parts of the body. These three-dimensional forms, however, may limit the degree to which seats containing the ergonomic devices can fold up. 
   Although some systems have been designed which promote the flattening of ergonomic support devices upon folding of a seat, many such systems are heavy and can be noisy during use, and are complicated and costly to assemble. Furthermore, due to the high spring rate of the springs incorporated into many of these designs, some systems can require a large amount of force to fold the seat down. The higher spring rate requires the use of heavier gauge components, which of course weigh more, and places more stress on the system&#39;s components over the long term. 
   The purpose of the present invention is to provide back support for a seat occupant, plus fold to a very thin profile when the seat is in the stowed position, while solving one or more of the above-identified problems. 
   SUMMARY OF THE INVENTION 
   In one aspect the invention is an adjustable lumbar support for a seat comprising a pair of parallel lateral rails, wherein each of the lateral rails has a lower end and an upper end, a support panel having a top end and a bottom end, the support panel pivoting at the top end while remaining fixed with respect to the lateral rails, a rail bracket slidably attached to the lateral rails, a spring operatively connected to the rail bracket, wherein the spring biases the rail bracket in a first position, a cable operatively connected to the rail bracket, wherein the cable pulls the bracket from the first position to a second position, and a lift wire pivotably attaching the support panel to the rail bracket. 
   In another aspect the invention is an adjustable lumbar support for a seat comprising a pair of parallel lateral rails, wherein each of the lateral rails has a lower end and an upper end, a lower base wire fixedly attached to the lower ends of the lateral rails, a support panel having a top end and a bottom end, the support panel pivoting at the top end while remaining fixed with respect to the lateral rails, a rail bracket slidably attached to the lateral rails, a spring operatively connected to the rail bracket, wherein the spring biases the rail bracket in a first position, a cable operatively connected to the rail bracket, wherein the cable pulls the bracket from the first position to a second position, and a lift wire pivotably attaching the support panel to the rail bracket, wherein the cable is slidably disposed within a conduit, a first end of the cable being fixedly attached to the rail bracket, a first end of the conduit being operably connected to the lateral rails, a second end of the cable and a second end of the conduit being operably attached to an actuator, wherein upon actuation the actuator increases tension on the cable thereby shortening the first end of the cable and causing folding of the support panel. 
   In yet another aspect the invention is a method of folding a lumbar support, comprising providing a pair of lateral rails, each rail having a top end and a bottom end, providing a support panel having a top end and a bottom end, wherein the support panel pivots at the top end while the top end remains fixed with respect to the lateral rails, slidably attaching a rail bracket to the lateral rails, operatively connecting a spring to the rail bracket wherein the spring biases the rail bracket in a first position, operatively connecting a cable to the rail bracket to pull against the force of the spring, providing a lift wire pivotably attached to the rail bracket and pivotably attached to the support panel, and pulling the cable so as to move the rail bracket from the first position to a second position. 
   A method of folding a lumbar support, comprising providing a pair of lateral rails, each rail having a top end and a bottom end, providing a pivoting support panel, slidably attaching a rail bracket to the lateral rails, operatively connecting a spring to the rail bracket wherein the spring biases the rail bracket in a first position, operatively connecting a cable to the rail bracket to pull against the force of the spring, providing a lift wire pivotably attached to the rail bracket and pivotably attached to the support panel, and pulling the cable so as to move the rail bracket from the first position to a second position, thereby causing the support panel to move closer to the lateral rails. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  shows a perspective view of one embodiment of a lift wire lumbar assembly according to the present invention; 
       FIGS. 2A and 2B  show a side view of the lift wire lumbar in a seat that is unfolded and folded, respectively; 
       FIG. 3  shows a perspective view of another embodiment of a lift wire lumbar assembly according to the present invention; 
       FIG. 4  shows a seat frame with a folding-activated actuator attached; 
       FIG. 5  shows a close-up, cutaway view of one embodiment of an actuator; and 
       FIGS. 6A through 6D  show possible configurations of the pivot bracket, which vary depending on whether the bracket clips or threads onto the lift wire and frame wire. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   In one embodiment a lift wire lumbar  20  comprises a grid  22  pivotably attached to a base wire  24  ( FIG. 1 ). Grid  22  is pivotably attached to a lift wire  26  via a pivot bracket  28  at a distance from the lower end of grid  22 . Lift wire  26  is also pivotably attached to a rail bracket  30 . Rail bracket  30 , in turn, is slidably attached to base wire  24 , along the two parallel side portions thereof, the side portions also called lateral rails  24   c . Grid  22  pivots relative to base wire  24  at pivot points  40 . When the lift wire lumbar system is installed in a vehicle seat, appropriate connections are made between the frame of seat back  60  and base wire  24 . Thus in use base wire  24  remains relatively stationary in relation to the frame of seat back  60  while grid  22  moves under various conditions, for example upon folding and unfolding of the seat. Base wire  24  is attached to a seat frame  58  by various known means, for example using attachment clips  46  which wrap around base wire  24  and which comprise integral snap-in fasteners. 
   In general lift wire lumbar  20  comprises a support panel that is capable of supporting a seat occupant, the panel being pivotably attached to seat back  60  and pivotably attached to lift wire  26 . Lift wire  26  in turn is itself pivotably attached to rail bracket  30 , which is slidably attached to lateral rails  24   c . In the embodiment described herein the support panel comprises grid  22  and grid  22  is pivotably attached to base wire  24 , of which lateral rails  24   c  form a part. In a preferred embodiment grid  22  pivots at its top end  22   a  ( FIG. 1 ). 
   Base wire  24  can assume various configurations provided that base wire  24  comprises a pair of lateral rails  24   c  and a means for securing these to seat back  60 . In one embodiment base wire  24  also comprises an upper base wire  24   a  portion and a lower base wire  24   b  portion connected to lateral rails  24   c  ( FIG. 1 ). 
   Grid  22  comprises a frame  42  across which are attached a series of approximately parallel horizontal crosswires  44 . Frame  42  consists of two roughly parallel side portions joined by top and bottom portions. It is crosswires  44  that primarily support the seat occupant&#39;s back, although in the lumbar region lift wire  26  may also contribute to supporting the occupant&#39;s back, depending on the particular design of lift wire  26  that is employed. In one embodiment lift wire  26  is attached to a point closer to the bottom of grid  22 , thereby giving greater support to the lumbar region of the occupant&#39;s back. 
   Pivot bracket  28  can be designed to attach to grid  22  in several different ways ( FIGS. 6A-6D ). Pivot bracket  28  can snap onto lift wire  26  and the border of grid  22  ( FIG. 6D ), or can alternatively be designed with a hole through which lift wire  26  and the border of grid  22  are threaded ( FIG. 6C ), or a combination of both ( FIGS. 6A ,  6 B). In the embodiment shown in  FIG. 6A , pivot bracket  28  snaps onto frame  42  of grid  22  while lift wire  26  is threaded through pivot bracket  28 . With any method, an important feature is that pivot bracket  28  is held firmly onto grid  22 , so that it does not move in relation to the border of grid  22 , while permitting lift wire  26  to pivot relative to pivot bracket  28 . 
   Lift wire  26  can be a single wire that extends between the two pivot brackets  28  and down to interact with rail bracket  30  ( FIG. 1 ). Alternatively lift wire  26  may extend between the two pivoting points on rail bracket  30  and extend forward to interact with pivot brackets  28 , leaving the space between pivot brackets  28  open. In another alternative, lift wire  26  may consist of two separate pieces, each of which extends only between one pivot bracket  28  and the corresponding end of rail bracket  30 . Finally, lift wire  26  may be a complete rectangular piece of wire that extends between both pivot brackets  28  and both ends of rail bracket  30 . 
   In response to folding and unfolding of the seat back  60  in which lift wire lumbar  20  is installed, rail bracket  30  moves up and down along base wire  24 , respectively, causing lift wire  26  to pivot relative to pivot bracket  28  which in turn causes grid  22  to fold and unfold (see arrow C in  FIGS. 2A ,  2 B). Rail bracket  30  is preferably pulled up by a cable  32 , against the tension of an extension spring  34 , and pulled down by spring  34  when the tension on cable  32  is released. Cable  32  is housed in a conduit  36  and slides axially therein. One end of conduit  36  is operably connected to base wire  24 . In one embodiment a cross support  38  is attached to base wire  24  for the purpose of anchoring an end of conduit  36 . Cable  32  at this end of conduit  36  is fixedly attached to rail bracket  30 . Also attached to rail bracket  30  is one end of spring  34 . The opposite end of spring  34  in one embodiment is fixedly attached to the non-pivoting end of base wire  24  ( FIG. 1 ). In a preferred embodiment cable  32  and conduit  36  are of a type commonly referred to as “Bowden” cables wherein cable  32  and conduit  36  are flexible. 
   The other end of conduit  36  and cable  32  are anchored to an actuator  56  ( FIGS. 4 and 5 ). Actuator  56  may be of a conventional motor- or manually-operated design, or in a preferred embodiment is driven by the folding movement of a seat frame  58  ( FIGS. 4 and 5 ). The other end of conduit  36  and cable  32  are anchored to actuator  56  which is integrated into seat frame  58  such that folding of seat back  60  towards seat bottom  62  increases tension in cable  32 , shortening cable  32  and leading to cable  32  pulling on rail bracket  30 , which ultimately leads to folding of grid  22  into a more compact conformation. The length of the lateral portions of lift wire  26  plus the amount of travel on the parallel side portions of base wire  24  will determine the amount of movement of grid  22  in response to pivoting of lift wire  26 . 
     FIG. 5  shows one possible mechanism for generating tension on, and subsequently shortening, cable  32  in response to folding down of a seat back  60 . Cable  32  is fixedly attached to the front of a torsion bar  48 , optionally to a pulley  50  which itself is fixedly attached to torsion bar  48 . Having an intervening pulley  50  permits adjustment of the length of cable  32  that is taken up upon folding of the seat, by varying the radius of pulley  50 . Similar adjustment can be made by varying the radius of torsion bar  48  if pulley  50  is omitted. If pulley  50  is employed, the end of cable  32  can be attached to pulley  50  via a notch  52  on pulley  50 , into which an attachment at the end of cable  32 , such as a bullet, can be inserted. In the absence of pulley  50 , other well-known means can be used to securely attach the end of cable  32  to torsion bar  48 . 
   The attachment point of cable  32  to torsion bar  48 , with or without pulley  50 , is contained within a housing  54 . Conduit  36  is operably attached to housing  54  such that conduit  36  will not enter housing  54  under the levels of tension expected to be present during use of the system described herein. In one embodiment housing  54  is fixedly attached to a non-folding portion of the seat frame  64  while torsion bar  48  is fixedly attached to the folding portion, which in one embodiment is seat back  60 . Upon folding down of the seat back (arrow B in  FIG. 4 ), torsion bar  48  rotates forward (see direction indicated by arrows A in  FIGS. 4 and 5 ) while housing  54  and conduit  36  remain stationary. Rotation of torsion bar  48  and the optional pulley  50  therewith increases tension on, and consequently shortens, cable  32 . As torsion bar  48  or pulley  50  rotates, a given length of cable  32  is wrapped onto torsion bar  48  or pulley  50  thereby shortening the effective length of cable  32  by the amount taken up by torsion bar  48  or pulley  50 . Since housing  54  is fixed with respect to torsion bar  48  or pulley  50 , as cable  32  begins to shorten it moves axially within conduit  36 . Because cable  32  slides axially within conduit  36 , the shortening of cable  32  at the end proximal to the torsion bar  48  causes shortening at the opposite end, leading to upward movement of rail bracket  30  and thus to folding of grid  22  relative to base wire  24  via lift wire  26 . The extent of shortening of cable  32  depends on the amount of angular movement of torsion bar  48  relative to housing  54  as well as the radius of the object around which cable  32  is wrapped, either pulley  50  or torsion bar  48 . 
   Comparable results are also obtained if torsion bar  48  is held fixed while housing  54  moves with the folding portion of the seat, provided that cable  32  is wrapped around the back side of torsion bar  48  or pulley  50 . 
   In one embodiment rail bracket  30  slides up and down along base wire  24 , causing lift wire  26  to pivot relative to grid  22 . When rail bracket  30  moves upward, this moves lift wire  26  into a position that is closer to being parallel to grid  22 . What is meant by “closer to being parallel,” which is also referred to herein as “substantially parallel,” is that the angle between lift wire  26  and the lateral rails of base wire  24  is less than 45°. This in turn causes grid  22  to fold into a more compact conformation. 
   When rail bracket  30  slides downward this causes lift wire  26  to move into a position that is closer to being perpendicular to grid  22 . What is meant by “closer to being perpendicular,” which is also referred to herein as “substantially perpendicular,” is that the angle between lift wire  26  and the lateral rails of base wire  24  is at least 45° and no more than 90°. This places grid  22  into its activated position, in which grid  22  can support a seat occupant. 
   In one embodiment lift wire  26  when in its activated position is closer to being perpendicular to base wire  24  and grid  22 . By having lift wire  26  closer to a perpendicular angle relative to base wire  24  and grid  22 , this transfers more of the force required to hold grid  22  in its unfolded, activated position directly from grid  22  to lift wire  26  to base wire  24  with less of a requirement for spring  34  to hold rail bracket  30  and lift wire  26  in place. This relatively high angle orientation of lift wire  26  permits the use of a spring with a relatively low spring rate. This lower spring rate, in turn, allows the seat to be folded using less force. Overall, the lower spring tension required by this system permits the use of lighter-weight components and less wear on the system. 
   In a preferred embodiment lift wire  26  when in its activated, unfolded position is nonetheless at an angle relative to base wire  24  and grid  22  of less than 90°, i.e. an acute angle, which permits lift wire  26  to collapse readily under high impact, for example as could result from a vehicle collision. In one embodiment this angle is 60°. 
   In an alternative embodiment, instead of having a single, centrally-located extension spring between rail bracket  30  and the lower end of base wire  24  as shown in  FIG. 1 , there can be one or a pair of compression springs  34 A axially mounted on the side rails of base wire  24  between rail bracket  30  and the top end of base wire  24  ( FIG. 3 ). 
   The lift wire plays a critical part in the design of the system. The lift wire can be installed with the portion connecting the side pieces of the lift wire attached to the pivot brackets. This will provide firm support in the lumbar area. The lift wire can be installed with the connecting portion that connects the side portions of the wire attached to the rail wires in the grid, plus the location of the connecting portion of the lift wire enable the design to easily accommodate the requirements for occupant back support. 
   As stated above, the combination of the angle of the lift wire compared to the base wire and grid, plus the spring rate of the spring, will determine the force the unit can support and also the force required for stowing the unit. When the lift wire is near 90 degrees to the base and the grid border wires, it takes a small amount of force on the base bracket to support the grid in the extended position. This small force enables the use of a spring with a low spring rate. When the unit is collapsed for the stow position, the low spring rate allows a small amount of force on the cable and a small force on the seat back by either a person or a powered back unit. Also note that when the angle of the lift wires goes from near 90 degrees to near 0 degrees to the base wire, the force of the spring increases on the base bracket; the change in angle of the lift wire enables a much smaller load on the grid to collapse the unit. The force on the grid will happen when the seat back is being forced against the seat cushion for the stowed position. The lighter spring rate results in lighter components and less wear for the system. The lift wire is designed to be near 90 degrees during occupancy of the seat. However, movement would not be detrimental to the unit. 
   As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.