Abstract:
A vehicle seat includes a head restraint which limits the magnitude of neck deflection of a vehicle occupant during a rear impact collision. The head restraint includes a support member attached to the top of a head restraint post. The support member includes a convex surface shaped to substantially conform to the profile of an occupant&#39;s head and neck. The support member is covered by a resilient material such as foam. The foam thickness is reduced due to the presence of the support member. Reduced foam thickness in addition to the shape of the support member provides for reduced occupant neck deflection during a rear impact collision.

Description:
BACKGROUND OF INVENTION  
       [0001]     The present invention pertains generally to vehicle seats, and more particularly to a head restraint which minimizes a vehicle occupant&#39;s neck deflection during a rear impact event.  
         [0002]     Occupants of motor vehicles have long suffered head, neck and spinal injuries during events such as rear vehicle impact or sudden deceleration. Typically, a vehicle head restraint is constructed with compressible foam surrounding a head restraint post. In a rear impact event, the occupant&#39;s head contacts the top of the vehicle head restraint with sufficient force to result in a significant deflection of the foam. The magnitude of neck deflection increases as the head further compresses the foam. Furthermore, because the foam is sufficiently resilient, the energy imparted to the foam by the occupant&#39;s head is mostly stored and not dissipated. As such, when the rear collision event has ended, the energy stored within the foam is released into the occupant&#39;s head which causes it to fling forward possibly causing further injury to the vehicle occupant.  
         [0003]     Accordingly, it would be advantageous to provide a vehicle head restraint which includes a comfortable support surface during normal operation and a structure which limits the deflection of the occupant&#39;s neck during an event such as a rear impact collision. Furthermore, it would be advantageous to provide a head restraint including components which are easily adaptable for use with existing head restraint posts and seat structures. It would also be advantageous to provide a head restraint for a seat which may be economically constructed.  
       SUMMARY OF INVENTION  
       [0004]     In accordance with the present invention, a head restraint for a vehicle seat limits the neck deflection of a vehicle occupant during a rear impact collision. In another aspect of the present invention, the head restraint includes a support member attached to the top of a head restraint post. The support member includes a convex surface shaped to substantially conform to the profile of an occupant&#39;s head and neck. The support member is covered by a resilient material such as foam. The foam thickness is minimized due to the presence of the support member. Minimized foam thickness in addition to the shape of the support member provides for minimized occupant neck deflection during a rear impact collision.  
         [0005]     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 DRAWINGS  
       [0006]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0007]      FIG. 1  is a perspective view of an exemplary vehicle equipped with a vehicle seat having a head restraint assembly constructed in accordance with the teachings of the present invention;  
         [0008]      FIG. 2  is a partial exploded perspective view of a vehicle seat constructed in accordance with the teachings of the present invention;  
         [0009]      FIG. 3  is a partial perspective view of a support member and head restraint post of the seat assembly depicted in  FIG. 2 ;  
         [0010]      FIG. 4  is a cross-sectional side view of the head restraint assembly of the present invention;  
         [0011]      FIG. 5  is a schematic side view depicting a vehicle occupant in relation to a vehicle seat during normal operation of the vehicle;  
         [0012]      FIG. 6  is a schematic side view depicting the position of a vehicle occupant relative to the vehicle seat of the present invention during a rear impact collision; and  
         [0013]      FIG. 7  is a partial exploded perspective view of an alternate embodiment seat assembly constructed in accordance with the teachings of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0014]     The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0015]      FIG. 1  depicts an exemplary motor vehicle  10  having a seat  12  constructed in accordance with the teachings of the present invention. Seat  12  includes a head restraint assembly  14 , a seat back  16  and a seat bottom  18 . Seat back  16  is pivotally coupled to seat bottom  18 . Head restraint assembly  14  is adjustably coupled to seat back  16  such that the head restraint assembly may be vertically positioned relative to the seat back depending on the physical characteristics of the vehicle occupant. It should be appreciated that the “2-way” adjustable embodiment shown is merely exemplary and that the head restraint assembly of the present invention may be used in conjunction with a “4-way” adjustable seat and head restraint assembly without departing from the scope of the present invention.  
         [0016]      FIGS. 2-4  depict seat back  16  including a frame  20 , bushings  22  and end caps  24 . Frame  20  includes a pair of side rails  26  interconnected by a top rail  28 . Top rail  28  includes a pair of apertures  30  extending therethrough. Bushings  22  are positioned within apertures  30 . Each bushing  22  includes a tubular segment  32  having a flange  34  positioned at one end. Tubular segments  32  extend through top rail  28 . Each flange  34  abuts an upper surface  36  of top rail  28  when bushings  22  are mounted to frame  20 . End caps  24  are coupled to bushings  22  and provide an aesthetically pleasing cover for the bushings. One of the end caps  24  includes a locking mechanism with a release lever  38  extending therefrom. The locking mechanism normally engages a portion of the head restraint assembly  14  to maintain the vertical position of the head restraint assembly relative to the seat back. If adjustment of the vertical height of the head restraint assembly relative to the seat back is desired, the vehicle occupant operates release lever  38  to disengage the locking mechanism and allow movement of head restraint assembly  14  relative to seat back  16 .  
         [0017]     Head restraint assembly  14  includes a head restraint post  40 , a support member  42  and a pad  44 . Head restraint post  40  is preferably constructed from a metal tube or rod bent to resemble the shape shown in the figures. Head restraint post  40  includes a pair of substantially parallel, vertically oriented leg portions  46  interconnected by a substantially horizontally oriented crossbar portion  48 . Each leg portion  46  includes a seat back engaging section  50 , a pad engaging section  52  and a transitional section  54  interconnecting seat back engaging section  50  and pad engaging section  52 .  
         [0018]     Support member  42  is preferably an injection molded plastic component. However, support member  42  may be constructed from sheet steel, aluminum or any other suitable structural material. Support member  42  includes an arcuate wall  56  bounded by end walls  58 . Arcuate wall  56  and end walls  58  define a generally hollow shell  60 . Inner clips  62  are integrally formed with and extend from an inner surface  64  of arcuate wall  56 . Ribs  65  provide structural support for inner clips  62  along inner surface  64 . Each inner clip  62  includes an inner arcuate surface  66  engaging crossbar portion  48  of head restraint post  40 . Inner arcuate surface  66  defines an arc length greater than 180 degrees. Accordingly, inner clips  62  are snap-fit to crossbar portion  48  to retain support member  42  to head restraint post  40 . Outer clips are formed integral with and adjacent to end walls  58  of support member  42 . Each outer clip  68  includes an arcuate wall  70  having a slot  72  extending therethrough. Each wall  70  includes an inner surface  74  engaging a leg portion  46  of head restraint post  40 . Inner surface  74  defines an arc length greater than 180 degrees to assist in retaining support member  42  to head restraint post  40 .  
         [0019]     Arcuate wall  56  of support member  42  includes an outer convex surface  76 . Outer convex surface  76  defines a radius in the range of 10 to 60 millimeters. This radius range has been shown to be beneficial in distributing load imparted to head restraint assembly  14  by a vehicle occupant&#39;s head during a rear impact collision. A radius of 50 mm may be preferable. As was mentioned earlier, it is highly desirable to limit the maximum neck deflection of a vehicle occupant during a rear impact collision. By sizing convex surface  76  as previously described, the maximum deflection of the vehicle occupant&#39;s neck is reduced.  
         [0020]     Pad  44  is preferably constructed from a urethane foam of a type typically used to make head restraint pads. Pad  44  encompasses support member  42  to provide an aesthetically pleasing and comfortable surface for supporting the vehicle occupant&#39;s head. Pad  44  may be separately molded and slit to accept support member  42  or may be directly injection molded over support member  42  and the uppermost section of head restraint post  40 . A fabric cover  78  encloses pad  44 . Pad  44  is sized and shaped to minimize the deflection of the vehicle occupant&#39;s neck during a rear end collision. Specifically, head restraint pad  44  includes an outer convex surface  80  spaced apart from outer convex surface  76  of support member  42 . Outer convex surface  80  defines a radius sized to conform to the geometry of the posterior side of an occupant&#39;s head and neck. A thickness  82  of pad  44  located between outer convex surface  80  and outer convex surface  76  is defined to be in the range of 20 to 60 millimeters. This range of thickness assures that a vehicle occupant&#39;s head is sufficiently cushioned during the collision while at the same time assuring that load is transferred to support member  42  to resist further neck deflection of the vehicle occupant.  
         [0021]      FIGS. 5 and 6  depict the angular relation of a vehicle occupant&#39;s head to its torso before and during a rear impact collision. Specifically, angle A of  FIG. 5  exists when the occupant is traveling in a vehicle under “normal” conditions.  FIG. 6  shows the change in head to torso orientation as increased angle B. Because support member  42  effectively reduces thickness  82  of pad  44 , the maximum neck-deflection is reduced. Furthermore, because support member  42  includes specifically sized outer convex surface  76 , the magnitude of load imparted to the posterior side of the vehicle occupant&#39;s head is maintained within reasonable limits. Additionally, the amount of foam between the vehicle occupant&#39;s head and the support structure has been reduced by the present invention to store less energy within the foam during the rear impact event. As such, the tendency of the compressed foam to fling the vehicle occupant&#39;s head forward after the rear impact event is reduced.  
         [0022]      FIG. 7  depicts an alternate embodiment seat  84 . Alternate embodiment seat  84  is substantially similar to seat  12 . Accordingly, like elements will maintain the previously introduced reference numerals. Seat  84  includes a head restraint post  86  including a pair of substantially parallel leg portions  88  interconnected by a crossbar portion  90 . Crossbar portion  90  follows a serpentine shape having two peaks  92  interconnected by a trough  94 . It should be appreciated that inner clips  62  of support member  42  are spaced apart to engage peaks  92  of head restraint post  86  or the corresponding locations of the crossbar portion  48  of head restraint post  40 . By constructing support member  42  in this manner, a single support member may be used in seats utilizing either embodiment head restraint post.  
         [0023]     Furthermore, the foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without departing from the spirit and scope of the invention as defined in the following claims. For example, head restraint post  40  may be formed from alternate materials such as aluminum, magnesium, plastic or any number of structural materials. Additionally, the head restraint post need not be formed as a unitary tubular structure, but may include rectangular cross-sectional portions, flanges and additional support brackets as deemed necessary without departing from the scope of the present invention.