Patent Publication Number: US-2002011723-A1

Title: Control system for air bags in different vehicle locations

Description:
RELATED APPLICATIONS  
     [0001] This application is a continuation of U.S. patent application Ser. No. 09/033,739 filed Mar. 3, 1998 entitled “Control System for Air Bags in Different Vehicle Locations” which is a continuation-in-part of U.S. patent application Ser. No. 08/826,612 filed Apr. 4, 1997 entitled “Lap Mounted Inflatable Bag And Method Of Use” which was in turn a continuation-in-part of U.S. patent application Ser. No. 08/665,121 filed Jun. 14, 1996 entitled “Lap Mounted Inflatable Bag And Method Of Use,” which was abandoned Oct. 8, 1997. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] Inflatable elements, bag or belt, deploying from locations adjacent vehicle occupants have been proposed and suggested to distribute belt loading during a collision (U.S. Pat. No. 3,682,498 and 3,841,654).  
       [0003] Prior restraint systems have combined seat belts, including lap and shoulder components, with inflatable members. For example, vehicle air bags have been proposed to be mounted adjacent shoulder belts and lap belts for deployment upon rapid deceleration of a vehicle (U.S. Pat. No. 5,062,662). Other prior inflatable bag vehicle restraint systems have required that the bag be supported by a portion of the vehicle in front of the occupant (i.e., the dashboard or wheel post unit). Further, prior lap belt mounted bags were deployable in front of the occupant&#39;s belt and have not caused the lap belt to have its slack removed by the inflation of the bag.  
       [0004] Finally, it has been proposed to provide bags for inflation between the occupant and shoulder straps (U.S. Pat. No. 3,971,569).  
       [0005] None of the prior art proposals provide proper protection where the restraint system can only be deployable from and restrained by a lap belt area.  
       SUMMARY OF THE INVENTION  
       [0006] The present invention comprises an occupant vehicle restraint system in which a configured inflatable air bag is supported by a lap belt. The lap belt is positioned adjacent the bag or in a passageway in the air bag which passageway is part of the inflatable pressure-retaining envelope of the bag. The bag is sized and shaped so that the force of the occupant&#39;s torso tending to move forward in a rapid deceleration of the vehicle is restrained by the bag engaging a sufficiently large support area consisting of the top portion of the occupant&#39;s legs and a variable seat surface between the occupant&#39;s legs. The belt-receiving passageway may be located so that a rear portion of the bag is inflatable between the belt and the occupant and the remainder of the bag is inflatable forward of the belt to prevent any substantial rotation of the torso.  
       [0007] By so locating the belt-engaging bag surface or the belt-receiving passageway, a rear portion of the bag when inflated tightens the lap belt as such rear portion presses against the occupant&#39;s lap upper thigh portion and lower stomach area. At the same time the forward portion of the bag inflates to serve as a structural air stiffened column to provide a restraint against the occupant&#39;s forward movement and rotation of the occupant&#39;s torso.  
       [0008] The present inventive restraint system and its method of operation utilizes an air bag deployed from the lap belt area which bag as deployed is fully supported and constrained by (1) the lap belt and (2) surfaces including occupant&#39;s legs and the surface upon which the occupant is seated. The invention is particularly useful for occupants seated in seats that are not adjacent a dashboard or a wheel post. Occupants in the back seats in passenger land vehicles and airplane passengers are readily protectable utilizing the present inventive restraint system. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009]FIG. 1 is a perspective view of an occupant in a front seat with a lap belt and folded air bag prior to inflation;  
     [0010]FIG. 2 is a partial perspective view similar to FIG. 1 showing the folded bag in a rupturable pouch prior to inflation and illustrating the looseness with which the belt may be worn and still be effective;  
     [0011]FIG. 3 is a diagrammatic plan view of the occupant and inflated bag;  
     [0012]FIG. 4 is a view similar to FIG. 1 showing the bag as first inflated;  
     [0013]FIG. 5 is a view similar to FIG. 4 after inflation with the occupant&#39;s torso having moved forward a small distance;  
     [0014]FIG. 6 is an alternative embodiment in which the bag includes an upper blister for additional head support to further reduce head rotation to a lesser angle;  
     [0015]FIG. 7 is a bottom view of the bag prior to folding;  
     [0016]FIG. 8 is a partially folded view of the bag;  
     [0017]FIG. 9 is a schematic diagram showing the forces and torques created during rapid deceleration of the vehicle and bag deployment;  
     [0018]FIG. 10 is a further schematic diagram showing forces and torques upon initial bag inflation where the lap belt is positioned within a bag passageway;  
     [0019]FIG. 11 is a front elevational view of an embodiment of the present invention in which an inflatable member is mounted in a lap belt system which includes an inflation arrangement;  
     [0020]FIG. 12 is a front elevational view of an inflated bag of particular shape;  
     [0021]FIG. 13 is a front elevational view of an inflated bag with upper expansion pockets prior to their inflation;  
     [0022]FIG. 14 is a side perspective view of the bag of FIG. 12 after inflation;  
     [0023]FIG. 15 a  is a side perspective view of the bag of FIG. 13 with an upper expansion pocket being deployed;  
     [0024]FIG. 15 b  is a view similar to FIG. 15 a  in which a further pocket is deployed;  
     [0025]FIG. 15 c  is a side elevational view in which the bag pockets shown in FIGS. 15 a  and  15   b  are fully deployed;  
     [0026]FIG. 16 a  is a front elevational view of a bag having side pockets which bag has been inflated without side pocket deployment;  
     [0027]FIG. 16 b  is a view similar to FIG. 16 a  in which the side pockets are deployed;  
     [0028]FIG. 16 c  is a front elevational view of a bag including a head side support section;  
     [0029]FIG. 17 is a partial schematic view of the belt sections, tongue and buckle arrangement with an undeployed inflatable member;  
     [0030]FIG. 18 is a partial sectional view through the tongue unit and inflatable member of FIG. 17;  
     [0031]FIG. 19 is a schematic view of a belt arrangement with the inflator in the buckle and the connectable tongue unit;  
     [0032]FIG. 20 is a schematic view of a belt arrangement showing the inflatable member attached to the buckle and with the inflator in the tongue unit;  
     [0033]FIG. 21 is a perspective view showing the tongue unit and buckle detached with transformer portions on each;  
     [0034]FIG. 22 is a sectional exploded view of a belt anchor;  
     [0035]FIG. 22 a  is a side view of the anchor of FIG. 22 including the belt section;  
     [0036]FIG. 22 b  is a sectional view of a belt section taken along line  22 b- 22 b of FIG. 22;  
     [0037]FIG. 22 c  is a view similar to FIG. 22 b  with the belt section having a gas passage formed therein by gas pressure;  
     [0038]FIG. 23 is a front elevational view of a further bag embodiment with an opening therethrough for centered lap belt buckle and tongue manipulation;  
     [0039]FIG. 24 is a side perspective view of a further configured bag embodiment with the lap belt positioned against the bag surface;  
     [0040]FIG. 24 a  is a schematic diagram of the bag of FIG. 24 positioned illustrating a passenger&#39;s torso and legs at a 90° angle;  
     [0041]FIG. 24 b  is a further schematic similar to FIG. 24 a  in which the torso-to-leg angle is greater than 90°;  
     [0042]FIG. 24 c  is a further schematic in which the angle is 90° and bag sections theoretically overlap;  
     [0043]FIG. 25 is a perspective view of occupants in rows of seats in which lap mounted bags deploy row-by-row;  
     [0044]FIG. 26 is a schematic of a row of seats, inflation arrangements and controls for such inflation arrangements; and  
     [0045]FIG. 26 a  is a schematic of a row of seats, inflation arrangements and controls for such inflation arrangements using a radar collision signaler.  
     [0046]FIG. 27 is a schematic and circuit diagram for controlling inflation of a bag or bags properly timed after rapid vehicle deceleration. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0047] In FIGS. 1, 3 and  4 , occupant&#39;s (O) seat  12  with seat surface  12   s  and seat back  12   b  are mounted on vehicle floor  13 . Occupant (O) is shown in passenger seat  12  with lap belt  16  across occupant&#39;s (O) lap. Lap belt right portion  16   a  is engaged in belt extension  24  which in turn is anchored in right floor anchor  14  in vehicle floor  13  and the left belt portion  16   b  is secured to the vehicle floor  13  by left floor anchor  15 . Alternatively, lap belt may have two sections and a buckle.  
     [0048] With reference in particular to FIG. 3, bag  18  with exterior inflatable cloth body  19  has a cloth passageway  21  between slot portals  21   a ,  21   b  through which lap belt  16  is passed. Cloth body  19  together with cloth passageway  21  comprise the pressure-retaining envelope  18   e  of bag  18  into which envelope  18   e  the gases of inflation are introduced or formed. Lap belt  16  is readily slidable back and forth through passageway  21  when bag  18  is deflated. Such movement provides for adjustment of bag  18  with respect to the occupant. Bag  18 &#39;s gas inlet neck  22  (FIG. 7) can be connected to gas conduit  23  extending from a remote location such as the floor  13 . Gas conduit  23  is supplied gas from a storage gas container or a pyrotechnic gas inflator or a combination thereof, and alternately the inflation source may be contained within the bag  18 .  
     [0049] Turning to FIG. 2, an alternative embodiment is shown in which folded bag  18  is covered by an elongated rupturable pouch  20 . Bag  18  is shown folded for positioning in pouch  20  in a ready-to-deploy position with belt  16  loosely positioned for the comfort of the occupant. This alternative system has a gas-generating inflator positioned in bag  18  or pouch  20 .  
     [0050]FIG. 4 shows bag  18  with the alternate inflation entrance of gases from conduit  23  through neck  22 . Bag  18 , as inflated, is generally round in shape as viewed from above (FIG. 3) and generally triangular in shape as viewed from the side (FIG. 4). Bag  18  has a bottom seat surface and leg engaging surface  18   a ; a torso engaging surface  18   b  and front non-engaging surface  18   c . Surfaces  18   a  and  18   b  intersect along occupant&#39;s waistline (WL). Since belt  16  passes through bag passageway  21  which is distance (d) from the occupant&#39;s waistline (WL), the inflation of bag portion  18   r  to the rear of belt  16  pushes occupant (O) back and down in his or her seat as bag  18  is first inflated (see FIGS. 4 and 5). This action also removes any slack that may have existed in belt  16  due to looseness of wearing. Further, the inflation of the bag  18  and the creation of inflated bag space also displaces bag over spaces  18   h  and  18   r  toward the occupant&#39;s chest and upper leg, respectively. Front bag portion  18   f , the remaining portion of bag  18 , is forward of the belt  16 . Front bag portion  18   f  functions to support and resist rotation of occupant&#39;s (O) torso (T) as forces of vehicle deceleration act on torso (T). Bag  18  may also include a set up reinforcing cloth panel  25  to strengthen bag  18  in the belt-engaging area which must withstand forces of inflation and occupant restraint as the vehicle decelerates.  
     [0051] It is contemplated that inflation of bag  18  is accomplished sufficiently rapidly, using inflators of stored gas or pyrotechnic type or combinations thereof, so that the occupant&#39;s lap belt  16  is tightened by inflation of the rear bag portion  18   r  prior to forces of deceleration acting on the occupant&#39;s (O) torso (T) which force tends to move the torso (T) forward in rotational movement about belt  16 . Only a few degrees of torso (T) rotation is permitted by the compression of bag  18 . Any additional torso rotation will depend on the occupant&#39;s seated position and whether bag  18  rests on the occupant&#39;s legs, seat surface  12   s  or combination of both. Bag  18  is shown in FIG. 5 engaging seat surface  12   s  over area  12   a  as torso (T) is decelerated. Torso rotation is preferably less than 10° from the vertical. However, depending on the occupant&#39;s size and the size and shape of the bag, rotation of the torso may be up to 30°.  
     [0052] With particular reference to schematic FIG. 9, horizontal force (F 1 ) represents the force exerted by occupant&#39;s torso at a distance X from lap belt  16  creating a torque (T 1 ). To resist torque (T 1 ) bag  18  generates an equal and opposite torque (T 2 ). Torque (T 2 ) is force (F 2 ) times distance (Y).  
     [0053]FIG. 10 is also a schematic showing the embodiment in which the belt passes through the bag with bag portion  18   r  inflating between the belt and the occupant. Initial bag inflation causes the bag to push the occupant back of vertical line (V) 15° (note the 90° angle of FIG. 9 and the 105° angle of FIG. 10). Bag portion  18   r  pushes the occupant down in the seat and bag portion  18   h  pushes occupant back in his seat.  
     [0054] Bag  18  when inflated is restrained from forward movement by lap belt  16 . Bag  18  rotates a few degrees as it is acted on the forces of the occupant&#39;s torso deceleration. Bag  18  is shaped and sized to prevent substantial torso rotation of any occupant including a large man. Smaller occupants will experience even less torso rotation. Bag  18  has a bag exterior surface  18   a  which engages a substantial area of occupant&#39;s legs and seat surface between the occupant&#39;s waist and knees. Bag  18  also has a surface  18   b  for engaging a substantial portion of the torso from the waist to the head. Bag  18  may also be sized to support occupant&#39;s head. Preferably, bag surface  18   a  engages ⅓ to ⅔ of occupant&#39;s upper legs. Upper legs are the portion of the legs between the hips and knees. Bag surface  18   a  also engages the seat surface over the seat surface area between occupant&#39;s legs.  
     [0055] In a further alternative embodiment shown in FIG. 6, bag  18  includes deployable blister  34 . As occupant&#39;s (O) torso (T) exerts forces of compression on bag  18  increasing the gas pressure therein to a selected threshold allowing stitches  35  to rupture so that blister section  34  inflates to provide support for the occupant&#39;s (O) and head (H).  
     [0056] Turning to FIG. 7, uninflated bag  18  has bottom surface  31 , passage outlet ends  21   a ,  21   b  and gas inlet  22 . FIG. 8 shows uninflated bag  18  with outside portions  28 ,  29  folded to positions adjacent central bag bottom portion  30  which central portion  30  is approximately the width of belt  16 .  
     [0057]FIG. 11 illustrates a further embodiment of the present invention in which the inflatable member  36  which may be of any shape and configuration is foldably mounted on lap belt system  38  which system has positioned in it the entire inflation arrangement. Tongue unit  39  is connected to a tongue belt section  41  which in turn is attached to tongue belt section anchor  43 . The belt system  38  also includes a buckle  45 , a buckle belt section  46  and a buckle anchor  48 . Occupant (O) seated on seat  49  is restrained by belt system  38 . Upon inflation of inflatable member  36  further occupant protection is provided as described below.  
     [0058] Turning to FIG. 12, an inflatable member in the form of bag  55  is shown which bag  55  has a particular shape including leg-engaging bag wings  56 ,  57  and a central blister section  59  which extends downwardly near to or against seat surface  51 . Whether blister section  59  engages seat surface  51  depends on the extent to which occupant&#39;s legs are initially spread apart and the extent to which blister  59  of bag  55 , as inflated, causes any further leg separation. Bag wings  56 ,  57  are positioned and shaped with widths d 1 , d 2 , respectively so that they properly serve both large and small occupants.  
     [0059] Turning to FIG. 13, bag  55 ′ consists of bag body  60  made of two stitched together bag panels (only panel  60   a  is shown) which include two upper stitched bag body pockets  64 ,  65  formed by tucking bag body panel material into the interior of bag  55 ′ and stitching such tucked-in panels to adjacent bag panels employing stitched generally-horizontal rows  67 ,  68  and  69 . Bag body pockets  64 ,  65  are deployable under selected circumstances described below to increase the bag size and shape.  
     [0060] In FIG. 14 deployment of bag  55  including its blister section  59  is shown (see also FIG. 12). The forward movement of occupant (O) is shown in dashed lines.  
     [0061] Turning to FIGS. 15 a - c , there is shown the stages of deployment of body pockets  64 ,  65  during inflation of bag  55 ′ when occupant-induced internal bag pressures reach predetermined levels. The reason for pocket deployment is to increase the size and height of bag  55 ′ to serve larger, taller and heavier occupants. As bag  55 ′ inflates to reach its full size, forces are exerted on the bag as it controls the occupant&#39;s movement including forward torso movement causing bag pressure to increase. If the occupant (O) is sufficiently larger and heavy, pressure will build up in bag  55 ′ to cause stitch rows  67 ,  68  and  69  to sequentially break and to deploy the body pockets  64 ,  65  as bag additions. FIG. 15 c  shows bag  55 ′ with both pockets  64 ,  65  fully deployed. As bag size increases by pocket deployment bag pressure is reduced for a given amount of gas in the bag; however, the forces acting on the occupant may remain the same since the area over which the forces act has been increased.  
     [0062]FIG. 16 a  shows use of side pockets  61 ,  62  created by generally-vertical stitch rows  61   a ,  62   a . Deployment of side pockets  61 ,  62  due to stitching failure is shown in FIG. 16 b . FIG. 16 c  illustrates bag  55 ″ with a head protecting portion  63 . Stitching bag panels using any suitable patterns are contemplated by the present invention to provide additional inflatable member size during inflation and the creation of forces resulting from occupant restraint.  
     [0063] As an alternative to non-stretch inflatable member material and the fracturable stitching described above, deployment of larger inflatable member volumes to accommodate larger occupants may be accomplished by fabricating inflatable members, such as bags, of expansible or stretchable material. Members made of fabrics or other materials which expand or stretch when inflated and when additional forces are applied by the occupant (O) during or after inflation are alternatively useful alone or in combination with non-stretchable materials.  
     [0064] Inflating systems positioned within the belt arrangement include a crash detector which sends a signal to an initiator which in turn initiates the function of an inflator causing the rapid flow of gases to the inflatable member. In FIG. 17 belt sections  41 ,  46 , buckle  45 , tongue unit  39  and uninflated member  36  are shown (see also FIG. 11).  
     [0065] Turning to FIG. 18, tongue unit  39  includes tongue housing  70 , tongue prong  71 , inflator  72 , and roller clamp  73  for adjusting the effective length of belt section  41 . Also shown are inflatable flexible member panels  36   a ,  36   b  of inflatable member  36  which engage tongue header pins  76   a ,  76   b , mounted in tongue header  77 . Header  77  includes header lock section  78 . After panels  36   a ,  36   b  are positioned on and around pins  76   a ,  76   b  slide lock section  78  is forced in place to hold the inflatable member panels  36   a ,  36   b  in place. Also shown is rupturable diaphragm  81  in gas passageway  82 .  
     [0066] In schematic FIG. 19, inflator  72  is located in buckle  45  and the origin of the electrical signal to cause inflator  72  to operate is located on the tongue side of the belt arrangement. Electrical wire  85  with tandemnly-connected wire sections  85   a ,  85   b  pass from crash detector  80  through belt section  41  and tongue unit  39  to buckle  45  into inflator  72 . Wire section  85   b  includes a socket  79  and wire section  85   a  includes a tapered head  80  shaped to enter socket  79  for electrical connection. This arrangement permits the crash detector to be located in the anchor that serves belt section  41  to provide the necessary tongue-to-buckle detachable connection. In FIG. 20, the inflator  72  is located in the tongue unit  39  and the inflatable member  36  is mounted on the buckle  45 . Gases generated in inflator  72  travel in gas passageway segments  86 ,  87  which segments are detachably connected by a nipple  88  and socket  91 .  
     [0067] Inflator  72  may be any suitable inflator; however, it is preferably a hybrid inflator with a pressurized housing having walls and with the propellant positioned therein spaced from the walls. Any suitable pyrotechnic material or propellant may be used to create the required gases. Preferable propellants whose bum time is in the sub-millisecond range when combusted at a pressure of approximately 25,000 psi are used in the practice of this invention. The materials (propellants) utilized should have extremely short function times. The materials should have web thicknesses (the thicknesses that the materials burn through during their combustion) that are small and that will complete combustion in a short time such as less than a millisecond.  
     [0068] Universal Propulsion designated 7019a propellant maybe used. The 7019a propellant is a propellant material including an oxidizer such as ammonium nitrate; a nitramine (preferably thermally stable) and a binder. The nitramine may be cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) or cyclo-1,3,5,7-tetramethylene-2,4,6,8-tetranitramine (HMX). Propellant 7019a is a solvent processed propellant which leaves a microscopic fine porosity throughout the quantity of propellant material positioned in inflator  72 . The binder should be a small percentage i.e. 4% of the material.  
     [0069] Propellant components should be proportioned to accomplish rapid and complete burning to produce gases which are environmentally sound and burn to reduce or eliminate inflator wall heating. The microscopic fine porosity in the propellant allows it to be produced with granules instead of as a single grain piece with each granule having a small web. The granules have the advantage of not being susceptible to cracks and the microporosity as well as the surface area created by the micro granules enable the propellant to be extremely quickly ignited. The propellant has high thermal stability and therefore requires high temperature to ignite it.  
     [0070] In hybrid inflators where propellants are stored under pressure of a gas such as an inert gas, chemical degradation is not enhanced and further the high pressure aids markedly in providing a high speed ignition and burning capability to the system. Extremely short burning times are best accomplished by burning these propellants in a very high pressure environment. Additionally, the small granules and microporse propellant leading to the ultra-thin web facilitate the fact that the propellant will be consumed before it can be explosively hurled into contact with the walls including side walls of the inflator  72 . The reduction or elimination of propellant striking the walls of the inflator housing reduces the rise in temperature of the inflator and facilitates its use adjacent or even in contact with the occupant.  
     [0071] Finally, inflator propellant materials may in addition include Hercules “Hi-Temp” brand propellant.  
     [0072] In FIG. 21, electrical signals are passed from tongue unit  39  to buckle  45  employing a transformer  93  with one transformer portion  94  of the transformer  93  in the buckle  45  and forming a part of buckle surface  45   s  and the other portion  95  of the transformer  93  in the tongue unit  39  and forming a part of tongue unit surface  39   s . Electrical signals generated in transformer portion  95  cause electrical signals to be generated in transformer portion  94 . Such signal transfer permits an electrical signal generated on one side of the belt system to be transmitted to the other side of the belt system so that the crash detector can be located on either side of belt system  38 . Also shown in FIG. 21 is crash detector  90  positioned on the tongue side for producing an electrical signal upon vehicle deceleration.  
     [0073] It is seen that when tongue and buckle are buckled and unbuckled, electricity and gas flow from one side of the lap belt to the other side of the lap belt which may be effected by the detachable connections described above or any other suitable arrangement.  
     [0074] In FIG. 22, 22 a  and  22   b , anchor  43  includes anchor cover  92  and anchor shielded housing  97  for shielding against extraneous radio waves or other waves that might prematurely activate the initiator. Also shown is anchor swivel unit  98 . Initiator  101  is mounted in housing  97  and an inflator (not shown) is positioned in swivel unit  98 . Gases generated in swivel unit  98  by the inflator pass through exit neck  103 , connector  105  into belt  104  which belt is constructed of two layers  104   a ,  104   b . Layers  104   a ,  104   b  separate upon application of gas-generated pressure to form gas passage  106  (see FIGS. 22 b ,  22   c ). Prior to inflation belt layers  104   a ,  104   b  may be stitched or glued together. The crash detector in anchor  43  (not shown) may be battery powered with low voltage being indicated by a light or an audible signal. Since the electrical requirements to operate the system are small, batteries located in the anchors may be used with replacement required only after five or more years.  
     [0075] Referring to FIG. 23, an alternate bag design is shown in which bag  108  has a central opening  107  to permit buckle  45  and tongue unit  39  to be readily operated in the central area of the occupant&#39;s lap. Central opening  107  is not part of the bag pressure-retaining envelope. Similarly, as stated above bag passageway  102  is not part of the pressure-retaining envelope of bag  108 . Central opening  107  may through alternate bag design be located on either side of the center of bag  108  as shown in FIG. 23. Belt  109  passes through bag passageway  102  which is divided into passageway sections  102   a ,  102   b  which sections  102   a ,  102   b  are separated by bag central opening  107 .  
     [0076] Finally, a further bag embodiment is shown in FIGS. 24, 24 a - c , which bag  110  consists of upper and lower sections  111 ,  112  and waist section  113  with lap belt  116  passing around bag  110  rather than through a bag passageway as described above in earlier embodiments. Belt  116  is positioned against bag waist section  113  upon inflation. Upper bag section  111  engages occupant&#39;s torso and lower bag section  112  engages the occupants legs and seat surface. Inflated belt section  113  which has belt  116  engaging its outer surface positions belt  116  distance X from occupant&#39;s waistline. Bag sections  111 ,  112  engage at line L and with added forces during deceleration and inflation bag portions  111 ,  112  may be forced further against one another.  
     [0077] Turning now to schematic FIG. 24 a , bag sections  111 ,  112  are sized to form a ninety degree (90°) angle A between the torso and legs of the occupant. FIG. 24 b  shows bag  110 ′ sized to form an angle B of  105  or more when sections  111 ′,  112 ′ touch at point P. In FIG. 24 c  bag sections  111 ″,  112 ″ of bag  110 ″ are shown being distorted by forces applied by the occupant as sections  111 ″,  112 ″ compress. Volume V represents the volume of theoretical overlap of sections  111 ″,  112 ″ if no bag section compression occurred. The volume or pressure of gases supplied to bag section  111 ″ may differ from the volume or pressure of gases fed to the bag section  112 ″.  
     [0078] It is contemplated that the present invention may be used in aircraft, school buses, passenger cars and other vehicles. In airplane applications having rows of seats, each row or portion should be equipped with a separate crash detector.  
     [0079] The present invention is particularly adaptable for use in aircraft or other vehicles where lap belts have been in common use for many years. Bags can be deployed from the lap belt area without need for installation of equipment in the seat backs located forward of the seated occupants. The invention provides protection for occupants, including pilots and passengers, of large or small aircraft.  
     [0080] In certain crashes of a large airplane in which the forward portion of the airplane may rapidly decelerate and come to rest while the rearward portion of the plane continues to decelerate, air bag deployment for effective occupant protection should occur in the forward part of the airplane before bag deployment occurs in the rearward portion of the plane. Commercial passenger planes with their long length are subject to a traveling crash wave within the plane. Where a crash involves the front of an aircraft striking a building, a mountain, the ground, or other object deceleration occurs in the forward part of the aircraft before it occurs in the rear of the aircraft. The points of rapid deceleration therefore move from front to back in a waveform. This waveform of deceleration requires that air bags in the front of the plane be deployed before air bags in the rear of the plane.  
     [0081] Turning to FIG. 25, three (3) rows of passengers are shown in which a forward row  124  is equipped with a gas supply unit  128  to serve that row. Gas supply unit  128  includes an initiator, an inflator and gas supply lines (not shown) which lines supply the bags mounted on the lap belts positioned across laps of the occupants in their seats. The inflator is sized to supply the air bags which serve each of the two (2) seats in row  124 . Gas supply unit  128  also includes a crash detector or other arrangement for creating a crash signal when a selected deceleration occurs at row  124 . The crash triggers the firing system creating a crash signal which in turn causes the initiator to ignite the inflator to rapidly create gases and supply them to the air bags in row  124 . The air bags of forward row  124  are in a state of deployment in which the bags have been fully filled with gas and the passengers&#39; torsos have swung forward.  
     [0082] Also shown in FIG. 25 is middle row  130  in which bag deployment has started and rearward row  132  in which the crash detector has not yet caused the air supply system to commence operation.  
     [0083] Alternatively, a gas supply unit may be positioned adjacent each individual seat in each row. Each supply unit may have its own crash detector firing system and inflator. An alternative arrangement for sequentially initiating bag deployment in a large aircraft is to have a single crash detector serve more than one row of seats.  
     [0084] When a crash detector serves more than one row of seats the signal serving the more rearward rows is preferably delayed so that bag deployment occurs when it can provide maximum protection for each of the occupants in each row. Deployment is timed to occur sufficiently in advance of rapid deceleration of the occupants to allow for bag inflation to provide maximum protection from injury or death.  
     [0085] Turning to FIG. 26 crash detector  133  serves three rows of seats. Forward row  135  has four (4) seats  135   a - d . Each seat has its own gas supply unit  136   a - d . Middle row  138  with four (4) seats  138   a - d  has each of its seats served by a gas supply unit  139   a - d  and rearward row  141  with seats  141   a - d  have gas supply units  142   a - d . Crash detector  133  supplies signals to each row along electrical conduits  144 ,  145  and  146 . The signals transmitted along conduit  144  cause the start of initiator, followed by, inflator activation, immediately after detector  133  measures a sudden deceleration. The signal transmitted along conduit  145  (which is simultaneously transmitted with the conduit  144  signal) is delayed by time delay  148  so that bag deployment in middle row  138  occurs after row  135  deployment. The signal transmitted along conduit  146 , again simultaneously transmitted with the  144  conduit signal, is also delayed by time delay  149  so that rearward row  141  is deployed after middle row  138 . An aircraft with forty (40) rows of seats would be equipped with a dozen or more crash detectors.  
     [0086] The crash detector and firing signal unit  133  include a firing system which produces a low voltage (amperage) signal. The system is preferably battery powered.  
     [0087] Turning to FIG. 27, circuitry for a crash detector is shown in which actuating lever  150  is moved with aircraft deceleration. Lever  150  moves when deceleration in that section of the plane occurs to in turn move switch arms  151   a ,  152   a  of switch  151 ,  152  respectively. Prior to the occurrence of a crash, switch arms  151   a ,  152   a  engage the upper stationary contact  151   u ,  152   u  of switches  151 ,  152  which short circuits capacitor  155  and resistor  156 . Switch  152  also provides a short circuit across pyrotechnic squib  158 . This prevents capacitor  155  from being charged and the squib  158  from being fired. In this pre-crash mode, the timing circuit  160  is powered by battery  161 .  
     [0088] Upon a crash, actuating lever  150  moves switch arms  151   a ,  152   a  to their lower positions causing a voltage to be applied by battery  161  through diode  162  to start terminal  163  of timing circuit  160 . Capacitor  155  becomes charged.  
     [0089] Timing circuit  160  times the preselected period. At the end of the period, the timing circuit  160  produces a series of pulses on line  166 . These pulses trigger the transistor  168  into a state of conductivity at the same frequency as the pulses. When the transistor  168  becomes conductive, a relatively low voltage is produced on the collector of the transistor  168 . This low voltage discharges the capacitor  155  and is introduced to the base of the transistor  170  to make the transistor  170  conductive. The pulses are filtered out by capacitor  155  as a result of the charging of the capacitor through a circuit including the battery  161 , the switch  151  and the base/emitter junction of the transistor  170 .  
     [0090] The flow of current through the transistor  170  causes a relatively high voltage to be produced across the resistor  156 . This high voltage establishes a state of conductivity in the transistor  176 . When the transistor  176  becomes conductive, it has a relatively low impedance. This causes a circuit to be established through the capacitor  172 , the switch  152  (in the second state of operation), the pyrotechnic squib  158  and the transistor  176 . The capacitor  172  then discharges through the pyrotechnic initiator  158  to fire the pyrotechnic initiator. The firing of the pyrotechnic initiator  158  initiates the operation of the inflator to inflate bags in a passenger row. U.S. Pat. No. 5,335,598 issued Aug. 9, 1994 and owned by the assignee of the present application discloses and claims the timing system including a timing circuit as described above. U.S. Pat. No. 5,335,598 is incorporated herein by reference.  
     [0091] The firing circuit and initiator  158  maybe housed in a single housing as disclosed and claimed in U.S. Pat. No. 5,499,579 issued Mar. 19, 1996 and owned by the assignee of the present invention. U.S. Pat. No. 5,499,579 is incorporated herein by reference.  
     [0092] The timing circuit  160  may utilize an input mechanism as the source of energy instead of a battery. An input electrical pulse, for example, of five (5) amperes and five (5) milliseconds, from an input mechanism is preferred rectified converting it to direct current which energy is stored in a capacitor as disclosed and claimed in U.S. Pat. No. 5,507,230 issued Apr. 16, 1996 and owned by the assignee of the present invention. U.S. Pat. No. 5,507,230 is incorporated herein by reference.  
     [0093] Where electrical noise may trigger premature activation of the initiator, Faraday shielding may be placed around the firing circuit or internal filtering may be used or both. The triggering signal may be filtered by a low pass filter (e.g. inductance and capacitance) to prevent noise from passing. Finite filtering may also be employed. A device (e.g. Zener diode) limits the triggering signal amplitude. The filtered triggering signal charges the capacitance in the low pass filter. The capacitor charge causes a second transistor to become conductive, thereby producing a voltage across an impedance. This voltage triggers the first transistor to the conductive state to provide for the firing of the initiator.  
     [0094] Faraday shielding and filtering are further described in U.S. Pat. No. 5,440,991 issued Aug. 15, 1995 and owned by the assignee of the present invention.  
     [0095] For another embodiment of the invention, the crash detector may be triggered by propagated energy waves such as radar waves rather than by aircraft deceleration. For example, a radar signal from a signaler  180  may be sent out by the airplane which signal would reflect off an object which is on a collision course with the airplane. The reflected signal would then trigger the crash detector to start the sequence of inflation row by row of the occupants&#39; air bags prior to the collision. A computer may be used to compute the time of the deceleration in various vehicle portions. By starting the inflation process, prior to collision, the time for deployment may be extended from twenty or forty milliseconds to 1000 milliseconds. For example, if an airplane is traveling at 120 mph (176 ft. per second) and the bag is deployed when the airplane is 176 ft from collision, a period of 1000 milliseconds may be provided for deployment to occur. Longer deployment times reduce the peak forces and pressure applied to passengers thus reducing the risk of injury by the bags during inflation.  
     [0096] The forces generated in the lap belts of the present invention are about one thousand (1000) pounds per side. Gas bag pressure upon full inflation is about 20 psig. Inflation times are between 10 and 1000 milliseconds.  
     [0097] Inflatable members other than bags such as belts may be useful in practicing the present invention. The embodiments of FIGS.  25 - 27  are also useful in vehicles other than airplanes such as trains, buses and elongated automobiles. Further such embodiments may employ the same inflators using the same pyrotechnic materials and propellants described herein.