Abstract:
A seat belt system including a seat belt secured for movement over a D-ring wherein the D-ring includes a magnet and the seat belt includes a plurality of magnetized metal filaments. As the seat belt travels through the D-ring the magnet attracts the plurality of metal filaments and counteracts at least a portion of the normal force of the webbing on the D-ring provided by gravity. The shape or configuration of the magnet may also increase the arc length or radial travel distance about the D-ring to reduce bunching and correspondingly the force necessary to wind and unwind the seat belt.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to a seat belt system for restraining an occupant of a vehicle and, more particularly, to a D-ring used to attach the shoulder portion of a seat belt in an automobile body assembly. 
         [0004]    2. Description of Related Art 
         [0005]    One type of seat belt system connects at three places to the vehicle body and incorporates both a lap belt section and a shoulder belt section to restrain movement of an occupant should sudden vehicle deceleration occur, for example a collision. The seat belt extends upward from a seat belt retractor, typically anchored to the vehicle body, to and through a D-ring, anchored to the vehicle body. The seat belt extends across the occupant&#39;s body and with a tongue received in a buckle securing the seatbelt in place. 
         [0006]    Various types of seat belt retractors are commonly used. One type of seat belt retractor includes a spool or reel including a torsion spring used to wind up and store the webbing of a seat belt. Some retractors use a motor that operates to wind and unwind the seat belt. As the seat belt is withdrawn or unwound from the spool or reel, it passes over the D-ring. Upon retraction, the seatbelt moves again over the D-ring in the opposite direction. 
         [0007]    The seat belt retractor provides sufficient force to retract the seat belt through the D-ring until it reaches a fully withdrawn position. To fasten the seat belt, the vehicle occupant exerts a force that overcomes the retraction force whereby the occupant can withdraw or pull the seat belt out of the seat belt retractor, over the D-ring, across the occupant&#39;s body and place the tongue in the buckle. Once buckled the seat belt retractor exerts a certain retraction force to remove any slack from the seat belt, which depending upon the severity of the retraction force, may cause a feeling of confinement. 
         [0008]    Reducing the retraction force needed to pull the seat belt back into the seat belt retractor and wind the seat belt around the spool reduces the pressure felt by the vehicle occupant during use. 
       SUMMARY OF THE INVENTION 
       [0009]    An embodiment of the present invention provides a D-ring and seat belt for use with a seat belt assembly of a motor vehicle. The D-ring includes a magnet and the seat belt includes a plurality of metal filaments. The magnet and plurality of metal filaments act together to counteract at least a portion of the force needed to draw the seat belt over the D-ring. In one example of the present embodiment, the magnet is positioned over or above the seatbelt and provide an attraction force that counteracts at least a portion of the normal force of the seat belt on the D-ring caused by gravity. 
         [0010]    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 
         [0011]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0012]      FIG. 1  is a perspective overview of a seat belt assembly incorporating a D-Ring and seat belt according to the present invention. 
           [0013]      FIG. 2  is a perspective view of a D-ring according to the present invention. 
           [0014]      FIG. 3  is a perspective view of a D-ring body and magnet according to the present invention. 
           [0015]      FIG. 4  is an exploded perspective view of a D-ring body and magnet according to the present invention. 
           [0016]      FIG. 5  is a side view of a D-ring body and magnet according to the present invention. 
           [0017]      FIG. 6  is a cross-sectional side view of a D-ring body and magnet according to the present invention. 
           [0018]      FIG. 7  is a cross-sectional side view of a D-ring assembly according to the present invention having a cover. 
           [0019]      FIG. 8  is a perspective view of a D-ring and seatbelt according to the present invention. 
           [0020]      FIG. 9  is a cross-sectional view of a seatbelt according to the present invention. 
           [0021]      FIG. 10  is a perspective view of an alternative embodiment of a D-ring body and magnet according to the present invention. 
           [0022]      FIG. 11  is a cross-sectional side view of the D-ring body and magnet illustrated in  FIG. 10 . 
           [0023]      FIG. 12  is a cross-sectional side view of the D-ring body and magnet as set forth in  FIG. 10  including a cover. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    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. 
         [0025]      FIG. 1  illustrates a seat belt system, seen generally at  10 , according to one example of the present invention. The seat belt system includes a seat belt retractor  12 . The seat belt retractor  12  typically operates to wind and unwind a seat belt  14  as the vehicle occupant pulls out and releases the seat belt  14 . The retractor  12  operates to take up slack in the seat belt  14  and during periods of rapid deceleration, for example a collision, to lock and prevent extraction of the seat belt  14 . As illustrated, the seat belt  14  passes through a D-ring  16  and a tongue  18 . The tongue  18  freely slides along the seat belt  14  and connects the seat belt  14  to a buckle  20 . In the disclosed system, one end of the seat belt  14  is fixed or anchored to the base/frame of the vehicle with the other end in the seat belt retractor  12 . The foregoing description of a seatbelt system  10  notwithstanding, the present invention functions or works with other seatbelt systems; including those with guides on the seats, mid-guides on the sheet metal or mid-guides on the B-side of trim panels. Since the D-ring  16  is one mechanism used to guide a seatbelt  14  the present invention is also suitable for use with other types of seatbelt guides. 
         [0026]    In the present example, the seat belt  14  is of a type having a bag-in-tube design; with an airbag  40 , see  FIG. 9 , built into or incorporated within a shoulder portion  15  of the seat belt  14 . The shoulder portion  15  of the seat belt  14  includes a tubular belt portion  44  with the airbag located and housed between the front  15   a  and rear  15   b  surfaces of the shoulder portion  15  of the seat belt  14 . If a frontal collision occurs, the airbag  40  inflates and opens the split in the tubular portion  44  when deploying in front of an occupant. The present invention may also be used with a standard web style seatbelt. In the present example, the invention includes a magnet located in or adjacent the D-ring and metallic filaments in the webbing of seatbelt. The magnet and metallic filaments cooperate to decrease the drag or friction force between the seatbelt and D-ring. 
         [0027]    As illustrated  FIGS. 2-7 , the D-ring  16  has a generally triangular shaped body  22  having side portions  24 ,  26  with a base or bottom portion  28 . The body  22  may be formed from a plate-like member and include a front face  25  and an opposing rear face  27 . An opening or slot  30  extends between the respective front face  25  and rear face  27 . In the present example, a stamping or press operation forms a flange or member  32  in the plate-like member adjacent the opening  30 . The flange or member  32  extends laterally on both sides of the front face  25  and rear face  27  of the body  22 . The flange  32  may extend laterally from only one of the front face or rear face  25 ,  27 . 
         [0028]    The flange  32  extending adjacent the opening  30  includes a guide surface  34 . The guide surface  34  having an arcuate configuration or curvature to facilitate movement of the seatbelt over the guide surface  34 . The curvature and the length of the guide surface  34  configured for each specific use. Further, increasing the size or length of the guide surface  34  correspondingly increases the width and the packaging constraints of the D-ring  16 . The width, that is the distance between the respective ends of the flange  32  on the front and rear faces  25 ,  27 , maybe limited depending upon the vehicle in which the D-ring  16  is used. 
         [0029]    The top portion  36  of the body  22  includes an attachment portion  38  that includes an aperture  40  used to pivotally attach the D-ring  16  to the vehicle or vehicle frame. In the present example, the body  22  also includes a cover  42 ; see  FIG. 7 , typically formed of a polymer that provides an aesthetically pleasing appearance and a low friction surface on the lower or guide surface  34 . 
         [0030]    The seatbelt  14  travels over the guide surface  34  when pulling the seatbelt  14  from the retractor or drawing the seatbelt back into the retractor. When traveling over the guide surface  34  the tubular portion  44  of the shoulder portion  46  of the seatbelt  16  containing the airbag  48  bunches upon entering and exiting radial turns; for example when traveling around or pulled over an arcuate surface having a tight radius. To combat and overcome the tendency to bunch, the D-ring  16  according to one example of the present invention includes a magnet  50  housed on or in a portion of the D-ring  16  opposite the guide surface  34 . The seat belt  14  includes a plurality of metal fibers or filaments  54  in or attached to the webbing of the seat belt  14 . As illustrated the shoulder portion  46  of the seat belt  14  includes metal fibers or filaments  54  on the interior surface  56 ,  58  of the front and rear surfaces  46 A,  46 B of the shoulder portion  46 . The metal fibers or filaments  54  extend along the longitudinal axis of the shoulder portion  46 . The magnet  50  acts on the metal fibers or filaments  54  in the shoulder portion  46  of the seat belt  14  to counteract the normal force on the D-ring  16  applied by gravity. 
         [0031]    In the example of the present invention, the magnet  50  is in a groove or channel  60  formed by an upper portion  62  of the flange  32 . Positioning the magnet  50  opposite and spaced from the guide surface  34  enables it to act on the metal fibers or filaments  54  in the shoulder portion  46  of the seat belt  14  to lift the shoulder portion  46  of the seat belt  14  as it travels through the D-ring  16 . Lifting the shoulder portion  46  negates adverse effects related to bunching when the shoulder portion  46  containing the airbag  40  is drawn over the D-ring  16 . 
         [0032]      FIGS. 10-12  illustrated a further example, wherein configuration, placement and number of magnets  50  housed in the D-ring  16  in combination with the metal fibers or filaments  54  in the shoulder portion  46  of the seat belt  14  increases the arc length or radius of curvature (r) of the seat belt  14 . Increasing the radius of curvature (r) makes it easier for the seat belt  14 , including the shoulder portion  466  to travel over the guide surface  34 . In this manner the radius of curvature is increased without having to make the guide surface  34  of the D-ring  16  substantially larger, that is increasing the width between the front and rear  25 ,  27  of the D-ring  16 . The magnet  50  also helps to reduce friction between the D-ring  16  and the seat belt  14  since it acts against the normal force provided by gravity of the shoulder portion  46  of the seat belt  14  on the D-ring  16 . 
         [0033]    As illustrated, the magnet  50  in  FIGS. 10-12  has a concave surface  70  complementary to the convex surface  72  of the upper portion  62  of the flange  32 . In this manner, the concave surface  70  of magnet  50  extends laterally between the respective front and rear  25 ,  27  of the D-ring  16 . The magnet configuration illustrated is but one example. The present invention contemplates using multiple magnets and multiple magnet configurations. 
         [0034]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.