Abstract:
A shock-load G-force minimizing seat structure which responds principally in non-springy compression, rather than in spring-loading bending, to vertically directed shock loads. The seat structure features an anti-springy frame structure which supports a thin and very lightweight seat cushion support spanner web formed preferably of a non-stretchy material, such as a material made out of elongate carbon-fibre strands.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention pertains to seat structure, and in particular to anti-spring, web spanner structure for supporting an occupant-seating cushion in seat structure designed for use in the setting of high-speed vehicle, such as an aircraft, to minimize injuries in hard and/or catastrophic impact events. The invention also pertains to such seat structure which further includes an anti-spring, compression-load seat-base structure. 
     Conventional seat design, insofar as it has been aimed at minimizing injuries caused from a hard “bottoming-out” event, such as in a crash landing in an aircraft, have typically introduced structural arrangements which, unfortunately, and to some extent accidentally, tend to exacerbate the impact-injury problem. Such design often utilizes a collapsing or “stroking” behavior in an effort to minimize the total load delivered to a seat occupant. This approach, however, frequently introduces undesirable weight, complexity, and expense issues, and also additionally enhances “springiness” in a seat structure—a situation that can actually lead to an amplification of damaging accelerations applied to a seat occupant&#39;s spine. Increased springiness, counter-intuitive as this may seem, introduces an enlarged rebound counter-acceleration fractions of a second after a dangerous impact occurs, and such increased counter-acceleration significantly contributes to serious, and often fatal, injury 
     The present invention addresses this issue with an innovative seat structure which, in use, is interposed a seat occupant and a vehicle frame, such as an aircraft frame, and which possesses substantially no spring-loading and spring-back behavior. This seat structure, disclosed in the environment of an aircraft, and in a preferred and best mode embodiment which is specifically illustrated and described herein, features a very thin, occupant-cushion-supporting spanner web formed of substantially non-stretchy and non-springy stand material, such as elongate carbon fiber, or Kevlar®, strand material, which is deployed under very modest tension between a pair of transverse, spaced, parallel, elongate and very robust cylindrical tubes. These tubes are carried on an adjustable, selectively fore and aft repositionable, slider sub-frame which, in turn, rides slideably on a pair of spaced, lateral and parallel I-beam-like rails (seat-frame substructures) which are, effectively, directly anchored to the aircraft frame. The mechanism furnished for enabling selectable slide repositioning, and positional unlocking and locking associated with this capability, do not form any part of the present invention, and are neither described nor illustrated herein. 
     These components of the seat frame—tubes, slider mechanism, rails and associated structures—load principally in very modest-deflection compression, rather than in bending, and consequently make an important contribution to the non-spring-back performance of the entire seat-structure. The spanner web, non-stretchable as it is, offers an extremely light weight, thin-format direct cushion support structure which also specially exhibits substantially no spring-loading, spring-back response to loading activity, such as an impact-produced sharp, high-level accelerative loading. 
     These and other features and advantages which are offered by the present invention will become more fully evident and appreciated as the description that now follows is read in conjunction with the accompanying drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 presents an isometric, side-frontal view of a preferred and best mode embodiment of seat-structure constructed in accordance with the invention. FIG. 1 includes a fragmentary illustration of an aircraft&#39;s frame structure with respect to which this seat-structure is anchored. 
     FIG. 2 gives a larger-scale, top-plan view (with seat-back structure removed) of what is shown in FIG.  1 . 
     FIGS. 3-5. inclusive, each present an even larger-scale, fragmentary view (partially cross-sectional) of structural details taken along the lines  3 — 3 ,  4 — 4 , and  5 — 5 , respectively, shown in FIG.  2 . 
     FIG. 6 presents three, story-telling, isometric views which describe, at least in part, assembly of the cushion-supporting spanner structure which is employed in the seat structure of the present invention. 
     FIG. 7 is a simplified fragmentary detail illustrating one modified form of the invention. 
     FIG. 8 is a fragmentary cross section taken generally along the line  8 — 8  in FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings, and referring first of all to FIGS. 1-5, inclusive, shown generally at  10  is a preferred and best-mode anti-spring-back seat structure which is constructed in accordance with the present invention. Very specifically, this illustrated seat-structure is constructed in accordance with a preferred and best mode embodiment of the invention. Illustrated fragmentarily at  12  is structure that represents an aircraft frame with regard to which seat-structure, or seat,  10  is suitable rigidly anchored. 
     Seat  10  includes a non-springy, rigid frame  14 , and mounted thereon, as will be described, a thin, nominally flexible, substantially unstretchable spanner web  15  of material which is intended to support an appropriate, direct occupant-supporting cushion which is shown at  16  in FIG.  1 . The design and construction of this cushion form no part of the present invention, but preferably, cushion  16  is made of a somewhat “soft” material which does not possess a springy nature. 
     Frame  14  includes lower and upper sub-frames  20 ,  22  respectively, which are functionally united, in the region designated  24 , for selected fore-and-aft relative positional sliding and adjustment as is represented by double-ended arrow  26 . The left and right lateral sides of frame  14  (from an occupant&#39;s point of view) are shown at  14   a ,  14   b  (see particularly FIGS.  1  and  2 ), and the front and rear sides of this frame are shown at  14   c ,  14   d , respectively. 
     Lower sub-frame  20 , also referred to herein as a mounting structure, includes two, elongate, laterally spaced, substantially parallel side members  20   a ,  20   b . These side members have a kind of I-beam-like cross section, with different-width upper and lower flanges joined by a central upright web, as shown. Members  20   a ,  20   b  are suitably anchored to the aircraft frame. 
     Upper sub-frame  22  includes two, elongate, laterally spaced, substantially parallel side members  22   a    22   b , each of which has the cross-sectional configuration clearly illustrated in FIG.  5 . As can be seen, the lower portion of each of these side-members has a downwardly facing, somewhat C-shaped look. Projecting upwardly from this lower portion is a substantially vertically disposed web which resides at the laterally outer sides of members  22   a ,  22   b . Members  22   a ,  22   b  are slideably mounted on members  20   a ,  20   b , respectively, in lower sub-frame  20 , with the C-shaped lower portions of members  22   a ,  22   b  receiving the upper flanges of members  20   a ,  20   b , respectively. Low-friction-material shoes  28 , made of a material such as ultra high molecular weight polyethylene (UHMWPE), are interposed these four lateral members ( 20   a ,  20   b ,  22   a ,  22   b ) as shown (see particularly FIGS.  4  and  5 ). 
     As was mentioned earlier, an appropriate mechanism (not shown) is provided for allowing a seat occupant selectively to adjust (in a lockable and unlockable manner) the fore and aft positions of members  22   a ,  22   b  on members of  20   a ,  20   b.    
     Further included in upper sub-frame  22  are elongate, front and rear, transverse members  22   c ,  22   d  respectively. These members, which are referred to herein as web anchor members, each has a stout, cylindrical/tubular configuration, with a central strengthening web which is partially removed adjacent opposite ends to accommodate the installation of closure end caps, such as end cap  30  which is shown in FIG.  5 . With specific reference to each end cap  30 , each cap includes a central, inwardly facing, hexagonal socket  30   a  which, in a sliding-fit fashion, receives a hexagonal nut  32  that receives a mounting bolt  34  which functions to anchor one end of the associated tubular member to the upright web in a upper sub-frame lateral member ( 22   a ,  22   b . A cross-nut-end-bolt assembly  36  is employed to capture each end cap within an end of one of the tubular members, with each hex nut  32  being initially freely received in a socket  30 a prior to assembly of each tubular member with an end of one of members  22   a ,  22   b . Collectively, members  22   a ,  22   b ,  22   c ,  22   d  define what is referred to herein as a rectangular, personnel support span, or region,  36  (see particularly FIGS.  2  and  3 ). 
     The several elongate components which make up the lower and upper sub-frames in seat-structure  10  exhibit substantially no springy bending under circumstances where a vertical load, such as an impact/shock load, is delivered between a seat occupant and the frame of the aircraft. Rather, these components respond to such a load primarily in compression. This is an important feature of the present invention. 
     Suitably anchored to members  22   c ,  22   d , and substantially entirely spanning previously mentioned rectangular region  36 , is previously mentioned spanner web  15 . Referring to FIG. 6 along with FIGS. 1-5, inclusive, web  15  is effectively a two-layer structure, including preferably an inner layer  40  and a jacketing, outer layer  42 . Inner layer  40  is formed of a substantially non-stretchable strand material, such as Kevlar® fabric material, which includes plural, elongate strands  40   a  (see FIGS. 2,  5  and  6 ) that end up extending in a fore-and-aft direction between upper sub-frame members  22   c ,  22   d . Layer  40  is preferably woven in nature, with cross fibres or strands having an orthogonal relationship. Outer jacketing layer  42  is formed preferably of rip-stop Nylon®. FIG. 6 shows how spanner web  15  may be formed. The several stages of construction are pictured in a quite self-explanatory way from left-to-right in the three views which are presented in FIG.  6 . Stitching  44  (FIGS. 2,  3  and  6 ) binds opposite ends of the effectively continuous loop of the spanner web in final stages of construction. The finished “loop” has a somewhat “figure-8” (with a flattened, offset center) configuration as viewed from a lateral side, or edge, of the loop. This configuration gives the spanner web a pair of opposite-end (front and rear) reverse loops  15   a ,  15   b , respectively. 
     While this spanner web has been described in conjunction with formation from a Kevlar® strand woven fabric material, it should be understood that other similar and suitable materials are and may become available made out of, for example, carbon-fiber material. 
     The completed spanner web is installed on sub-frame members  22   c ,  22   d  as shown, with the installed web nominally possessing a certain modest amount of tension whereby it does not sag between these sub-frame members. 
     FIGS. 7 and 8 illustrate a somewhat modified form of spanner-web construction and mounting. Here, such a modified web is shown fragmentarily at  46 . With regard to this modified web, the modifications exist at the two, opposite-end reverse bends which loop around upper sub-frame members  22   c ,  22   d . Specifically, at these two locations, two additional web layers  48 ,  50  have been added so that they lie intermediate previously described outer layer  42  and members  22   c ,  22   d  when the web is mounted in place. Layer  48  is joined directly to layer  42 , and is formed of an appropriate load-spreading material, such as Poron®  90 . Layer  50  is joined to layer  48 , and is preferably formed of an acceleration-rate-sensitive material, such as any one of the specific viscoelastic materials known as CF-42, CF-45, and CF-47. 
     OPERATIONAL DESCRIPTION 
     With an occupant in seat  10 , substantially the full weight of that occupant is borne by the spanner web. The web carries this load in non-stretching tension. From the spanner web, occupant load is transferred directly and dividedly to upper sub-frame  22  via front and rear tubular members  22   c ,  22   d , respectively, which respond to such load transfer, at least insofar as vertical load components are concerned, in compression rather than in springy bending. From members  22   c ,  22   d , this divided occupant load is transferred in compression to upper sub-frame members  22   a ,  22   b , through which members this transferred load is delivered in compression through shoes  28 , and lower sub-frame members  20   a ,  22   b , in compression, to the aircraft frame. 
     In the event of a catastrophic or other vertically jolting occurrence, G-loads delivered to an occupant through seat  10  upon initial impact will not cause any noticeable spring-back, vertical loading to occur in any portion of seat  10 . Hence, there will not occur any springy rebound in the seat frame and spanner web structure, and in particular not any rebound of the kind that we have learned is heavily responsible for delivering extremely damaging, and even fatal, injuries to a seat occupant. “Crash” tests performed with regard to the seat of this invention, with respect to “numbers” generated that relate to injury causation, are remarkably low, and have proven to be, consistently and repetitively, well below established “danger” thresholds. One important key to this remarkable behavior is the fact that, in sharp distinction relative to conventional seat structures, the seat structure of this invention does not introduce a damaging rebound response to impact events. 
     Accordingly, a preferred embodiment and methodology of the present invention have been described and illustrated herein. Counter-intuitively, the structure and methodology of this invention furnish a seat support structure including spanner web structure which, by reducing almost to non-noticeablity any spring rebound action with respect to a catastrophic vertical load imposed by a seat occupant on the seat structure, damaging G-force transmission to that occupant is significantly minimized. Those who are skilled in the art, after reading and reviewing the description and illustrations herein regarding this invention will appreciate that variations and modifications may be made without departing from the spirit of the invention.