Patent Publication Number: US-6338530-B1

Title: Lumbar support device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     None. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to devices that support the weight of a person in a seated position and particularly to devices that are capable of changing shape according to the occupant, and more particularly, this invention relates to devices that support and change shape according to the lumbar region of the occupant. 
     2. Related Art 
     Lumbar support devices have been integrated into seats to change their shape in the lumbar region, thereby allowing each occupant to adjust the support provided by the seat. The curvature and axial location of these devices are traditionally adjustable. When the back of the occupant engages the back of the seat, the curvature of the device presses the seat towards the occupant&#39;s spinal column, and the axial location of the device can be positioned according to the size of the occupant, thereby accounting for differences in the occupant&#39;s lumbar region with respect to the seat. It is generally known to provide manual actuation means and to alternatively provide powered actuation means for changing the curvature of the lumbar device and for changing the axial location of the lumbar device. 
     Typically, the curvature portion of these devices is constructed of a rigid material that is stamped into a particular shape or manufactured from individual components attached by hardware, such as rivets, screws, welds and bolts. Curvature changes are accomplished by bowing the curvature portion, usually pulling support structures toward each other. It is well known to pull on the supports with cables and some devices interpose structures between the supports to provide a mechanical advantage to the pulling action. In particular, U.S. Pat. No. 5,397,164 discloses a rod and a lever with springs and traction elements between supports and further discloses a cable running around a groove formed in a support plate in substitution for the lever. By substituting the cable running around the groove for the lever mechanism, the springs and traction elements are eliminated; however, the rod is required for both the lever mechanism and the grooved support plate. Additionally, the designs of these known devices require manual assembly operations, including the manual attachment of extension springs and assemblies requiring rivets or welds, and do not allow for a simplified assembly process. 
     Lumbar support devices using a resilient grid, such as those disclosed in U.S. Pat. Nos. 5,911,477 and 5,651,584 and incorporated by reference herein, provide good support qualities without excessive parts and are well suited for simplified assembly operations. These lumbar supports could be further improved with novel structures that provide a mechanical advantage and are also well suited for an automated manufacturing process. 
     SUMMARY OF THE INVENTION 
     It is in view of the above problems that the present invention was developed. The invention is a lumbar support device that can bow a flexible grid attached to a first bracket and a second bracket that slide on a track. Pulling on a cable segment that link the pair of brackets results in the bowing of the flexible grid. The cable segment is wrapped around the second bracket and is attached at its terminal end to the first bracket and its proximal end is engaged by a curvature cable actuator; wrapping the cable segment provides a mechanical advantage to the bowing resistance of the flexible grid. According to the present invention, the greatest mechanical advantage can be achieved by wrapping the cable segment around a pulley attached to the second bracket, and since no rod is necessary according to the present invention, this mechanical advantage can be achieved with fewer parts than the related art. The lumbar support device can also change the axial position of the flexible grid. A spring tension cable links an integrated bracket with the second bracket, and a compression spring is used to provide resistance to the cable and movement in an opposite direction. 
     In another embodiment, a lumbar support device includes a flexible grid that is bowed without any change in axial position. In yet another embodiment, a lumbar support device includes a grid that is moved axially without any change in curvature. 
     The track can be constructed from a base wire, known to be well suited to automatic manufacturing operations according to the patents incorporated by reference above and generally simplifying the assembly process. According to the patents incorporated by reference, it is known to slidably attach a bracket onto the base wire through apertures in the bracket and hold the bracket onto the base wire with bends in the base wire, to secure a bracket to the base wire between a dimple and a bend in the base wire, and to rotatably attach the flexible grid to a pair of brackets with a pair of pivot legs formed on each end of the border elements. Each of these attachments is accomplished using corresponding formations in the structures themselves, thereby eliminating any need for a weld, a rivet, or any other hardware. According to the simplified assembly process of the present invention, the integrated bracket slides onto the track and is secured to the track by a dimple at a fixed position in the track, the compression spring slides onto the track and is held in place between the integrated bracket and a slidably attached bracket, and the integrated bracket is linked with the second bracket using a press-fit connection at the end of the spring tension cable. For a powered lumbar support, the simplified assembly process also includes snap-fit connections between the integrated bracket and respective actuators. 
     Therefore, it is an object of this invention to provide a lumbar support unit capable of curvature movement having a mechanical advantage that uses fewer parts and hardware than the related art. 
     It is another object of the present invention to provide a lumbar support unit capable of axial movement that may be assembled with a minimum number of parts and hardware. 
     It is yet another object of the present invention to provide a lumbar support unit that is well suited to automatic assembly operations. 
     It is also an object of the present invention to provide a simplified assembly process for a lumbar support unit. 
     Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings in which like reference numbers indicate like elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the embodiments of the present invention and together with the description, serve to explain the principles of the invention. In the drawings: 
     FIG. 1 illustrates a perspective view of a lumbar support device capable of axial location and curvature changes according to the present invention; 
     FIG. 2 illustrates a plan view of the lumbar support device in FIG. 1; 
     FIG. 3 illustrates a side elevation view of the lumbar support device in FIG. 1 having a given position for axial location and curvature; 
     FIG. 4 illustrates another side elevation view of the lumbar support device in FIG. 1 having an alternate position to change the curvature; 
     FIG. 5 illustrates a side elevation view of the lumbar support device in FIG. 1 having an alternate positions to change the axial location; 
     FIG. 6 illustrates a plan view of a lumbar support device capable of curvature movement alone according to another embodiment of the present invention; and 
     FIG. 7 illustrates a plan view of a lumbar support unit capable of axial movement alone according to yet another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the accompanying drawings, FIGS. 1-5 illustrate a lumbar support device  10  according to the present invention, and according to this first embodiment, the device is capable of changing the axial position and curvature of a flexible grid  12 . Referring specifically to FIG. 2, the basic framework of the device is built on a track  14 , preferably a base wire  15  having substantially parallel sides  16 . A pair of brackets slide along both sides of the base wire, and the brackets hold opposite ends of the flexible grid  12 . More specifically, the first end  11  of the flexible grid  12  is attached to the first bracket  20 , and the second end  13  of the flexible grid is attached to the second bracket  22 . An integrated bracket  24  is held in place on the track  14  at a fixed position between the pair of brackets by a dimple  26 , preferably with a dimple on each side of the base wire. The integrated bracket respectively holds a curvature cable actuator  30  and a spring cable actuator  32  on each side of the base wire, preferably with a snap-fit connection  28 . The use of a snap-fit connection between the actuators and the integrated bracket minimizes the need for any hardware in the lumbar support unit. Also, a compression spring  34  slides over the track 14 , preferably on each side of the base wire  15 , and is held in place between the integrated bracket  24  and the second bracket  22 . 
     In addition to being attached to the flexible grid  12 , the first bracket  20  is linked to the second bracket  22  by a curvature tension cable  36 . Specifically, the curvature tension cable&#39;s terminal end  38  attaches to the first bracket  20  and its cable segment  39  wraps around a pulley  40  that is attached to the second bracket  22 . To complete the linkages between the first bracket  20  and second bracket  22 , the curvature tension cable&#39;s proximal end  42  is engaged by the curvature cable actuator  30 , extending through a first bowden cable  44  to the first bracket  20 . The sheath of the first bowden cable  44  is held in place at one end by a receiving end of the curvature cable actuator  30  and is secured to the first bracket  20  at the other end by a notch  45  formed in the first bracket. The integrated bracket  24  is linked to the second bracket  22  by a spring tension cable  46 . The spring cable actuator  32  engages one end  48  of the spring tension cable  46 , and a press-fit connection  50  secures the cable to the second bracket  22 . The spring tension cable  46  has a second bowden cable  52  whose outer sheath is held in place between the receiving end of the spring cable actuator  32  and a notch  53  in the integrated bracket  24 . 
     Referring also now to FIGS. 3,  4 , and  5 , the operation of the device is shown for both axial and curvature movement. To increase the curvature of the flexible grid  12 , the curvature cable actuator  30  pulls on the proximal end  42  of the curvature tension cable  36 , and its linear movement is transferred through the first bowden cable  44  to pull on the cable segment  39  joining the first bracket  20  to the second bracket  22 . The length of the cable segment  39  is reduced causing the first bracket  20  and second bracket  22  to slide towards each other according to the mechanical advantage provided by the pulley  40 . Each end of the flexible grid  12  is attached to the pair of brackets; therefore, as the distance between the brackets decreases the ends of the flexible grid are pulled together, resulting in the additional curvature of the flexible grid, specifically shown in FIG.  4 . 
     The curvature tension cable  36  provides the tension necessary to bow the flexible grid  12 , and the design of the flexible grid  12  provides resistance to being bowed. The flexible grid  12  has multiple flexible wires  54 , and each wire&#39;s ends are securely wrapped around a pair of coated wires  56 . It is the pair of coated wires  56  that actually bend and provide the bowing resistance. The multiple flexible wires  54  lie transverse to the bowing action and do not significantly contribute to the bowing resistance, but the stiffness of the multiple flexible wires force the coated wires  56  to bend in substantially parallel planes. Given the bowing resistance provided by the curvature of the flexible grid  12 , reducing the curvature of the flexible grid  12  is achieved when the curvature cable actuator  30  lets out the proximal end  42  of the curvature tension cable  36 . 
     To change the axial position of the flexible grid  12  in one direction, the spring cable actuator  32  pulls on one end  48  of the spring tension cable  46 , and its linear movement is transferred through the second bowden cable  52  to the press-fit connection  50  of the spring tension cable  46 , thereby pulling the second bracket  22  toward the integrated bracket  24 . The pair of compression springs  34  provide increasing resistance as the distance between the second bracket  22  and the integrated bracket  24  decreases; a change in axial position is specifically shown in FIG.  5 . To change the axial position of the flexible grid  12  in the other direction, the spring cable actuator  32  lets out the one end  48  of the spring tension cable  46 . Absent any actuation of the curvature tension cable  46 , the first bracket  20  and second bracket  22  slide in unison along the track, resulting in the linear movement of the flexible grid  12 . For a given curvature of the flexible grid  12 , it will be appreciated that the first bracket  20  is in a constrained relationship with the second bracket  22  due to the bowing resistance of the flexible grid and the length of the cable segment  39 . Therefore, only one of the pair of brackets  20 ,  22  needs to be pulled relative to the integrated bracket  24  for the flexible grid  12  to be moved axially, such as pulling on the first bracket  20 . 
     Various modifications could be made in the embodiment described and illustrated without departing from the scope of the invention. In particular, the use of the pulley  40  with the cable segment  39  provides the greatest mechanical advantage to achieve curvature movement with limited available power and a minimum number of parts. As discussed above, current methods suggest using a rod with a cable and either a lever or a groove. According to the present invention, less parts are necessary to obtain the mechanical advantage; only a cable segment  39  and a pulley  40  integrally incorporated into the second bracket  22 . It will be readily apparent that the pulley  40  can be substituted with a pin or could even be fixed groove that is formed in the second  22  bracket without any rod. The cable segment  39  provides a mechanical advantage in bowing the flexible grid  12  by doubling the curvature tension cable  36  in linking the first bracket  20  with the second bracket  22 . 
     As described above, a pair of motors drive the curvature cable actuator  30  and the spring cable actuator  32 , respectively. Without departing from the invention, it is well known that these power units may be substituted with mechanical linkages, thereby allowing manual operation of the lumbar support device. It is anticipated that the use of a snap-fit connection between the actuators and the integrated bracket may be also be used for attaching manually powered mechanical linkages. Therefore, the use of drive motors is exemplary, and well known techniques may be used for manually operating the lumbar support device according to the present invention. 
     Yet another modification could be made to the attachment of the flexible grid  12  to the pair of brackets without departing from the invention. As described and illustrated, the ends of the flexible grid are rotatably attached to the pair of brackets. The ends of the flexible grid could be fixedly attached to the pair of brackets as suggested by current methods. However, the rotation reduces the force necessary to bow the flexible grid and allows for more curvature than could be obtained had the ends of the flexible grid been fixedly attached to the pair of brackets. In a rigid attachment, the bowing of the flexible grid is inhibited at its ends by a constrained angle. 
     According to a second embodiment of the present invention, the lumbar support device  80  can change the curvature of a flexible grid  12  that is constrained to a single axial position. Referring specifically to FIG. 6, similarities with the first embodiment are found in the construction and operation of the device. The pair of brackets slide along the track  14  and hold opposite ends of the flexible grid  12 . The integrated bracket  24  slides onto the track between the pair of brackets and is held in place by a dimple  26  at a fixed position on the track. Prior lumbar support devices capable of curvature movement required hardware for attaching a bracket to a track or, according to the patents incorporated by reference, held a bracket between a dimple and a bend. According to the present invention, the dimple can be formed in the track during automated assembly operations without the need for any hardware to attach the integrated bracket to the track and without the need to form a bend in the track to hold the integrated bracket in place. 
     As in the first embodiment, the first bracket  20  is linked to the second bracket  22  by a curvature tension cable  36  using a press-fit connection  50 , and the curvature tension cable&#39;s proximal end  42  is engaged by the curvature cable actuator  30 . In this embodiment, the integrated bracket  24  only holds the curvature cable actuator  30 . The compression springs, spring cable actuator, and spring tension cable that were in the first embodiment are not necessary in this embodiment. 
     Similar to the first embodiment, the curvature of the flexible grid  12  is determined by the curvature cable actuator  30  pulling on the curvature tension cable  36  and the resistance of the flexible grid pushing back from the bowed position. In the second embodiment, both of the brackets do not need to slide on the track  14 , and it may be desirable to fix either the first bracket  20  or the second bracket  22 , allowing only one of the pair of brackets to move. The operation of the curvature tension cable  36  and the resulting curvature of the flexible grid  12  remain identical to the first embodiment. 
     According to a third embodiment of the present invention, the lumbar support device  100  can change the axial position of a grid  102  that is constrained to a single curvature. Referring specifically to FIG. 7, similarities with the first embodiment are found in the construction and operation of the device. Since the curvature of the grid  102  is not adjusted in this embodiment, a pair of brackets is not necessary and may be substituted with a bracket of unitary construction  104  that slides along the track  14 ; additionally, the grid  102  does not need to be flexible. The unitary bracket  104  has a first end  106  that holds the first end  101  of the grid  102  and a second end  108  that holds the second end  103  of the grid  102  on either side of the integrated bracket  24 . In this embodiment, the spring tension cable  46  links the integrated bracket  24  with the unitary bracket  104 , and the compression springs  34  fit around the track  14  between the integrated bracket and the second end  108  of the unitary bracket. As in the first embodiment, the track  14  holds the integrated bracket in place by a dimple  26 , and the integrated bracket  24  holds the spring cable actuator  32 . The pulley, curvature cable actuator, and curvature tension cable that were in the first embodiment are not necessary in this embodiment. Similar to the first embodiment, the axial position of the grid is determined by the spring cable actuator  32  pulling on the spring tension cable  46  and the resistance of the compression springs  34  pushing in an opposite direction. 
     In the third embodiment, the compression springs  34  do not need to be held between the second end  108  of the unitary bracket  104  and the integrated bracket  24 . Without departing from the invention, the compression springs  34  can be held in place between the first end  106  of the unitary bracket  104  and a bend  110  in the base wire  15 . Prior lumbar support devices capable of axial movement suggest using push rods and extension springs and other hardware that generally require some manual assembly operations. According to the present invention, the sides of the base wire can be automatically fed through the compression springs  34  that are easily held by assembly equipment. As in the prior two embodiments, the dimple  26  can be formed in the track during automated assembly operations without the need for any hardware to attach the integrated bracket to the track and without the need to form a bend in the track to hold the integrated bracket in place. 
     According to the description of the preferred embodiments above, the track can be constructed from a base wire. The use of a base wire as a track is known to be well suited to automatic manufacturing operations and generally simplifies the assembly process. The base wire has a closed end and substantially parallel sides that form an open end. According to the patents incorporated by reference, it is known to slidably attach a bracket onto the open end of the base wire through apertures in the bracket and hold the bracket onto the base wire with bends in the base wire (a slidably-attached bend-held bracket), to secure a bracket to the base wire between a dimple and a bend in the base wire, and to rotatably attach the flexible grid to a pair of brackets with a pair of pivot legs formed on each end of the border elements (or coated wires). Each of these attachments is accomplished using corresponding formations in the structures themselves, thereby eliminating any need for a weld, a rivet, or any other hardware. According to a simplified assembly process of the present invention, an integrated bracket slides onto a track and is secured to the track by a dimple at a fixed position in the track, a compression spring slides onto the track and is held in place between the integrated bracket and a slidably-attached bend-held bracket, and the integrated bracket is linked with the second bracket using a press-fit connection at the end of the spring tension cable. No hardware is required to hold each of these elements to the track or in relationship to each other, and the simplified assembly process is well suited for automated manufacturing operations. For a powered lumbar support, the assembly process can be further simplified by attaching the actuators to the integrated bracket through respective snap-fit connections. 
     The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. For example, the cable segment may be used with the pulley or the pin, or a groove in the second bracket, to perform substantially the same function in substantially the same way to produce the same result, and the pulley, pin, and groove are particularly described as equivalent structural elements. 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.