Abstract:
An apparatus for repositioning an occupant in response to a crash event including a seat, a pivot and an energy absorber. In response to the force of a crash, the energy absorber absorbs at least a portion of the energy of the crash and allows the seat to move to a more desirable position. An accelerometer may be used to generate a signal in response to a crash to activate an explosive charge and cause the seat to pivot to a more desirable position.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to seats for use in aircraft, such as, helicopters. More specifically, but without limitation, the present invention relates to a crashworthy seat that repositions the occupant prior to and/or during a crash event to increase the survivability of the occupant and decrease the harmful effects of a crash. 
     There have been many attempts to improve occupant survivability in a crash, especially with regard to helicopters. Such efforts have recently been directed to the occupant seat assembly including the seat frame, seat base and related parts. These crashworthy seat assemblies have been developed to stroke (i.e. to move usually in a downward direction relative to the aircraft floor) upon severe impact and usually activate energy absorbing devices thereby absorbing all or a portion of the crash energy transmitted to the seat. These seat assemblies may also be designed to plastically deform upon impact thereby absorbing an additional amount of the crash energy. As a result, the forces and accelerations experienced by an occupant in a crash are reduced and frequently minimize or eliminate injuries and save lives. 
     However, the amount of energy that can be absorbed is limited by the efficiency of the energy absorbing devices, the total distance available for the seat to stroke, and the energy absorbing capabilities of the plastically deformed seat assembly. In addition, it has been determined that a stroking seat sometimes causes the control stick of a helicopter to be impaled into the body or head of the pilot causing additional injuries. 
     Another problem associated with current seats is the positioning of the occupant. Most seats position the occupant in a substantially upright position prior to a crash. During a crash event, the seat remains substantially upright even in cases where the seat strokes or otherwise moves to absorb impact. As a result, an occupant&#39;s spine can be placed in severe compression from the force of the crash; the occupant&#39;s head and body are vulnerable to impacting the control stick or other object; the seat shoulder straps are subject to large forces which tend to stretch the strap material; the occupant is subject to submarining, that is, being forced under and out of the seat belt due to the force of the crash; and the occupant&#39;s internal organs are subjected to compressive forces due to, for example, compression of the abdomen. 
     There is thus a critical need in the art to provide an improved seat assembly that exhibits the benefits and advantages of existing designs and also provides additional protection during a crash event. 
     There is also a critical need to provide an improved seat assembly that exhibits the benefits and advantages of existing designs yet will prevent the control stick of a helicopter, for example, from contacting or being impaled into the body or head of the occupant. 
     There is a further critical need to provide an improved seat assembly that will place an occupant in a position that will reduce injury to internal organs and increase the magnitude of the crash event that an occupant can survive. 
     There is a critical need to provide an improved seat assembly that will reduce the undesirable effects of submarining and decrease the forces applied to the restraining belts. 
     There is another critical need to provide an improved seat assembly that can provide the improvements and benefits of the present invention while minimally impacting existing seat components, such as, restraint systems, inertia reels and armor plates. 
     SUMMARY OF THE INVENTION 
     Accordingly, the preferred embodiment of the present invention includes a seat for supporting an occupant, first and second energy absorbers for absorbing at least a part of the impact of a crash and a pivot for repositioning the seat to a more desirable attitude. In operation, the energy absorbing devices react to the force of a crash event when the force exceeds a predetermined value to allow or cause the seat to be repositioned to a more desirable attitude. Other embodiments of the present invention are included. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiment, the appended claims and the accompanying drawings in which. 
     FIG. 1 is a view showing the preferred embodiment of the present invention wherein the seat pivots about an axis. 
     FIG. 2 a  is a view showing an embodiment of the present invention wherein the seat moves in guide tracks. 
     FIG. 2 b  is a view-showing a typical guide track. 
     FIG. 3 a  is a view showing an embodiment of the present invention wherein an accelerometer and activator communicate to cause the seat to pivot about an axis. 
     FIG. 3 b  is a view showing an activator of the explosive type. 
     FIG. 4 is a view showing an embodiment of the present invention wherein wires are utilized to reposition and lift the seat. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The preferred embodiment of the present invention is illustrated by way of example in FIG.  1 . As shown in FIG. 1, crashworthy seat assembly  2  includes seat  4 , pivot tube  14 , and energy absorbers  28  and  30 . Seat  4  (supporting means) includes base  10  and back  12 . FIG. 1 shows pivot tube  14  attached to the forwardly portion of base  10 , end  14   a  extending outwardly from side  16  and end  14   b  extending outwardly from side  18 . Ends  14   a  and  14   b  communicate with bores  20  and  24  respectively via bearings  22  and  26  respectively. Note that bearing  22  is located in bore  20  of first rail  6  and bearing  26  is located in bore  24  of second rail  8 . One end of energy absorber  28  is attached to side  16  and the other end of energy absorber  28  is attached to first rail  6 . Likewise, one end of energy absorber  30  is attached to side  18  and the other end of energy absorber  30  is attached to second rail  8 . Energy absorbers  28  and  30  may be attached to other suitable locations such as, for example, the floor of a helicopter. In the embodiment of FIG. 1, it is preferred that energy absorbers  28  and  30  are located rearwardly of pivot tube  14 . However, it should be noted that the relative locations of pivot tube  14  and energy absorbers  28  and  30  may be changed to effect a different movement of seat  4  such as, for example, pivot tube  14  may be located more rearwardly than as shown in FIG. 1. A suitable and preferred energy absorber is part #100014-001, manufactured and commercially available from Simula Safety Systems, Incorporated, Applied Technologies Division, 7414 South Harl Avenue, Tempe, Ariz. 85283-4307. Other types of energy absorbing devices may be substituted by those skilled in the art, for example, a wire bending device, hydraulic damper or crushable honeycomb may be used. First rail  6  and second rail  8  are attached to a suitable attachment point such as the floor of a helicopter (not shown) and are positioned and arranged in a parallel fashion to communicate with ends  14   a  and  14   b  via bearings  22  and  26  respectively. It can thus be seen that when sufficient force is applied to energy absorbers  28  and  30 , for example, in a crash, seat  4  will deform energy absorbers  28  and  30  and pivot rearwardly about the longitudinal axis of pivot tube  14  thus causing an occupant to be repositioned to a more reclining position. Energy absorbers  28  and  30  control the speed and duration of rotation of seat  4  and limit the maximum degree of repositioning. Other energy absorbing systems, for example, stroking systems may be simultaneously or subsequently activated. It should be noted that seat assembly  2  may be fitted into existing systems and operate in conjunction with existing systems or operate independently of existing systems. 
     FIG. 2 a  shows another embodiment of the present invention wherein seat assembly  42  includes seat  44 , first rail  46  and second rail  48 . Seat  44  (supporting means) includes base  50  and back  52 . Base  50  includes first side  54  and second side  56  and back  52  includes first side  58  and second side  60 . Each side  54 ,  56 ,  58  and  60  includes a pair of rollers  62  attached to and extending outwardly from its respective side. First rail  46  includes first and second guide tracks  64  and  66  and second rail  48  includes first and second guide tracks  68  and  70 . 
     FIG. 2 b  shows a detail of guide track  66  and is typical of all the guide tracks  64 ,  66 ,  68  and  70 . Energy absorbing rectangular wire  72  (other shapes of wire may also be used) is located in the approximate center of guide track  66 . Rollers  62  are located inside guide track  66  on opposite sides of rectangular wire  72 . Note, that the diameters of rollers  62  are greater than one half the width of track  66  thereby causing rectangular wire  72  to form a curved, i.e. S, shape. It can thus be seen that rollers  62 , energy absorbing wire  72  and guide track  66  communicate in such a way that rollers  62  cannot move along the curves of its guide track without deforming its respective energy absorbing wire  72  (in an S shape) as it moves. Each guide track is shaped, for example, in the form of a curve thereby guiding its respective rollers (and seat  44 ) in the predetermined path defined by the curve. It should be noted that each guide track  64 ,  66 ,  68  and  70  along with its respective energy absorbing wire and rollers operate in a like fashion. Each guide track, energy absorbing wire and associated rollers form an energy absorbing device (EAD) and communicate to absorb energy and to guide a portion of seat  44  along the curve of that guide track. Each guide track may have a different curve, if desired. Prior to a crash event, each pair of rollers is maintained at one end of its respective guide track by the initial positioning (and sizing) of the energy absorbing wire  72 . Energy absorbing wire is attached to the guide track at this end. The other end of energy absorbing wire  72  may be unattached or attached to its respective guide track, for example, in the approximate center of the guide track as shown in FIG. 2 b . When a crash event occurs and the combined forces acting on the rollers  62  exceed the yield strength of the energy absorbing wires  72 , seat  44  moves along the predetermined path defined by the curves of guide tracks  64 ,  66 ,  68  and  70 , simultaneously and continuously deforming energy absorbing wires  72 . The bending of energy absorbing wires  72  dissipates a portion of the crash energy and allows seat  44  to be repositioned to a more desirable attitude. Seat  44  may be repositioned in any desired position and for many purposes such as, for example, to accommodate cockpit space limitations, to move the occupant away from potential hazards such as the helicopter control stick, and/or to accomplish a redistribution of the crash energy on the occupant. It should be noted that guide tracks  64 ,  66 ,  68  and  70  may also be configured to reposition seat  44  in an asymmetrical fashion, for example, base  50  may be repositioned downwardly and forwardly while back  52  may be repositioned downwardly and rearwardly. In such a case, it may be necessary to provide a pivot, for example, at the junction of base  50  and back  52 . It may also be desirable to effect a non simultaneous repositioning of seat  44  by providing energy absorbing wires of different yield strengths thereby allowing, for example, the energy absorbing wires of guide tracks  66  and  70  to first begin to yield and thereafter allowing the energy absorbing wires of guide tracks  64  and  68  to begin to yield. Obviously, many other configurations are possible. 
     FIG. 3 a  shows an embodiment of the present invention wherein seat assembly  80  includes seat  82  (supporting means), first rail  84  and second rail  86 . Seat  82  includes base  88  and back  90 . Base  88  includes first side  94 , second side  96  and front  97 . As shown in FIG. 3 a , seat  82  includes pivot  92  extending outwardly from first side  94  and second side  96  and located at the approximate junction of base  88  and back  90 . Seat  82  may pivot about the axis of pivot  92 . Pivot  92  communicates with bore  89  located in first rail  84  and with bore  91  located in second rail  86 . Both first rail  84  and second rail  86  are attached to suitable secure anchors such as the floor of a helicopter. Accelerometer  98  is located under seat  82  but may be located at other locations. 
     As shown in FIG. 3 b , activators  100  and  102  include hollow cylinder  104  having integral mounting ears  105  for attachment to, for example, first and second rails  84  and  85  or to the floor. End cap  106  seals first end  108 . Movable piston  112  is located within bore  114  and includes mounting arm  111  and flange  113 . Second end  110  is open to accommodate mounting arm  111 . Explosive material  116 , such as gun powder, is located in cavity  118 . Primer  120  is located proximate explosive material  116  and includes trigger wire  122 . Lip  109  prevents piston  112  from exiting bore  114 . Flange  113  of activator  100  is preferably attached to the forwardly portion of first side  94  and flange  113  of activator  102  is preferably attached to the forwardly portion of second side  96  but may be attached to other locations, for example, to front  97 . Trigger wires  122  of each activator are attached to accelerometer  98 . When a preselected acceleration is sensed by accelerometer  98 , such as in a crash event, a signal is generated by accelerometer  98  and delivered, via trigger wires  122 , to primers  120 , activating explosive materials  116 . The resultant gas pressure forces pistons  112  upwardly causing seat  82  to rotate about the axis of pivot  92  thereby repositioning seat  82  to a more reclining position. 
     FIG. 4 shows another embodiment of the present invention. As shown in FIG. 4, seat assembly  121  includes seat  123  (supporting means), first rail  124  and second rail  126 . Seat  123  includes base  128  and back  130 . First end  134  of pivot  132  extends outwardly from the forwardly portion of first side  138  and second end  136  extends outwardly from the forwardly portion of second side  140 . First end  134  sits in slot  135  and second end  136  sits in slot  137 . First end  141  of wire  142  is attached to first rail  124  at point  144  and extends rearwardly along upper portion  150 , under end  134  of pivot  132  and then over pivot  152 . The second end  143  of wire  142  is attached to anchor  154 . Similarly, first end  145  of wire  146  is attached to second rail  126  at point  148  and extends rearwardly along upper portion  156 , under end  136  of pivot  132  and then over pivot  158 . The second end  147  of wire  146  is attached to anchor  160 . When crash energy is progressively applied to base  128 , anchors  154  and  160  place wires  142  and  146  respectively, in progressively greater tension. Wires  142  and  146  pull up on ends  134  and  136  respectively, of pivot  132  thereby raising the forwardly portion of seat  123  and lowering the rearwardly portion. of seat  123 . It can thus be seen that seat  123  is repositioned to a more reclining position. 
     It can thus be seen that the present invention provides a seat assembly that can utilize energy sources, such as explosive charges, to reposition the seat to a more favorable position. It can also be seen that the present invention can utilize, either alone or in combination with other energy sources, the energy available from a crash event to cause the seat to be repositioned to a more favorable position. In addition, the present invention may act to absorb a portion of the crash energy thereby reducing the force of the impact event to the occupant. 
     Obviously, many modifications and variations of the.present invention are possible in light of the above teachings. It is therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.