Abstract:
A protective device ( 10 ) for protecting an occupant ( 7 ) of a vehicle ( 1 ), said protective device comprising an airbag ( 11 ) and inflation means ( 12 ) for inflating said airbag ( 11 ), the inflation means ( 12 ) being connected to the airbag ( 11 ) via a feed pipe ( 13 ) for feeding inflation fluid for the purpose of inflating the airbag ( 11 ) under predetermined conditions. This protective device further comprises expulsion means ( 20 ) for expelling said fluid, which expulsion means co-operate with at least one water detection means ( 15 ) so as to act when water is detected to remove said fluid resulting from inflation of the airbag ( 11 ), said airbag ( 11 ) being provided with a peripheral elastic strap ( 50 ) for optimizing the deflation of said airbag ( 11 ) when said expulsion means ( 20 ) allow said fluid to be removed from the airbag ( 11 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to FR 11 00267 filed on Jan. 28, 2011, the disclosure of which is incorporated in its entirety by reference herein. 
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to a protective device for protecting an occupant of a vehicle, to a seat, and to an associated vehicle. It relates more particularly to an aircraft, such as a rotary-wing aircraft. 
     (2) Description of Related Art 
     In particular, airbags are known that inflate when an impact occurs to protect an occupant of a vehicle. 
     Such airbags may be installed in dashboards, in seats, or in partitions defining the spaces for accommodating the occupant to be protected. As described in Document EP 1 616 760, it is also possible to provide reusable airbags in seatbelts, for example. 
     It is common for motor vehicles to have such airbags. Aircraft and in particular rotary-wing aircraft also sometimes have airbags. 
     Airbags make it possible to reduce the forces to which occupants of a vehicle are subjected during an accident in order to preserve their physical integrity. In addition, airbags limit the extent to which the heads of occupants of the vehicle move, and form barriers against impacts with the members of the vehicle that become potentially dangerous during such accidents. 
     However, an aircraft might have to make an emergency landing on a liquid surface, i.e. it might have to ditch. Certain emergency landing or ditching scenarios can require an airbag to be deployed for a non-negligible duration, rather than merely at a particular instant. 
     Deploying an airbag over a relatively long duration following a ditching on water raises a potential difficulty. There is a non-zero risk that the space surrounding an occupant of the aircraft might fill with water. The airbag can then constitute a major obstacle that needs to be overcome so that the occupant can exit from the aircraft before going under. 
     Documents U.S. Pat. No. 5,857,246 and U.S. Pat. No. 6,930,611 disclose devices suitable for opening a seatbelt buckle or seat harness buckle on coming into contact with a liquid. 
     Documents U.S. Pat. No. 4,498,604 and U.S. Pat. No. 4,260,075 disclose a device for inflating an article, such as a life jacket, on coming into contact with a liquid, that device involving a member that is soluble in water. 
     Document U.S. Pat. No. 6,024,116 also discloses such a device in a field remote from the problem to be addressed, namely the technical field of boilers. 
     In addition, it should be noted that Document U.S. Pat. No. 6,378,898 mentions the use of a system for deflating an airbag after a predetermined lapse of time. 
     Document EP 1 418 093 describes an airbag co-operating with inflation means. In addition, the described device is provided with a vent and with a tube, and with means for retaining the tube. 
     Finally, Document JP 11170963 would appear to describe a device for preventing an airbag from being triggered when in the presence of water. 
     BRIEF SUMMARY OF THE INVENTION 
     An object of the present invention is then to provide a protective device for protecting an occupant of a vehicle, and in particular of an aircraft, that is effective even in the event of contact with a surface of water, this protective device reducing or indeed removing the risk of unduly trapping the occupant in the vehicle, e.g. in the event that water enters the vehicle. 
     The invention provides a protective device for protecting an occupant of a vehicle, said protective device comprising an airbag and inflation means for inflating said airbag, the inflation means being connected to the airbag via a feed pipe for feeding inflation fluid for the purpose of inflating the airbag under predetermined conditions, in particular following an accident of the emergency landing type for an aircraft. 
     Reference can be made to the literature for obtaining information about airbag inflation means and about said predetermined conditions. 
     This device is remarkable in particular in that it further comprises expulsion means for expelling the inflation fluid, which expulsion means co-operate with at least one detection means for detecting a predetermined event so as to act when such a predetermined event occurs to remove said inflation fluid resulting from inflation of the airbag, subsequently to inflation of the airbag, the airbag being provided with a peripheral elastic strap for optimizing the deflation of the airbag when the valve allows the inflation fluid to be removed from the airbag. 
     Thus, under the predetermined conditions, the inflation means inflate the airbag so as to protect an occupant of the vehicle. For example, the inflation means inject air under pressure into the airbag. 
     Since the strap of the airbag is elastic, said strap stretches and does not hinder inflation of the airbag. 
     The expulsion means are then in a closed first position and prevent the inflation fluid from exiting from the airbag. It should be noted that the term “expulsion means” is used to mean a valve, a flap, or any other equivalent means, such as, for example, a piston, suitable for closing off an outlet orifice in the first position. 
     Conversely, if the detection means detect occurrence of a predetermined event, e.g. chosen from a list including the presence of water, the presence of fire, and the opening of a seat harness subsequently to inflation of the airbag, the detection means authorize the expulsion means to go over from the first position to a second position allowing the inflation fluid to be removed from the airbag. 
     Since the elastic strap is fastened to the casing defining the airbag or, for example, to two end zones of said airbag, the pressure exerted by said elastic strap on the casing delivers sufficient energy to drive the inflation fluid out of the airbag through the expulsion means. 
     Therefore, the airbag gives rise to hindrance that is at least minimized compared with the hindrance from a conventional protective device during evacuation of the occupant from the vehicle. 
     The invention may have one or more of the following characteristics. 
     For example, the expulsion means may be arranged on the feed pipe. The airbags are then not provided with any vents, thereby, in particular, making them easier to manufacture. The pressure exerted by the strap makes it possible for the expulsion means to be arranged in such a manner. 
     In another aspect, the expulsion means may comprise an outlet orifice for enabling the inflation fluid to exit towards the environment outside the device and a moving member suitable for preventing inflation fluid from passing through said outlet orifice in the absence of a predetermined event. The detection means then co-operate with the moving member to allow the inflation fluid to pass through the outlet orifice in the presence of said predetermined event, e.g. in the presence of water. 
     In an active, electrical embodiment, the detection means transmit an electrical signal to a control unit such as a microprocessor or equivalent electronic means for example, said control unit instructing an electric motor to move the moving member into the expulsion second position for expelling the inflation fluid. 
     In a passive mechanical embodiment, the detection means include water detection means provided with soluble means co-operating with the moving member. 
     For example, the soluble means are constituted by a soluble ring pressing a holding member against a locking portion of the moving member. In the presence of water, the soluble ring dissolves. As a result, the moving member is no longer held against the holding member and moves so as to occupy said second position. 
     In addition, the inflation means may firstly comprise an inflator connected to the airbag via the feed pipe, and secondly comprise a control unit connected to the inflator, the control unit instructing the inflator to inflate the airbag under said predetermined conditions. 
     For example, during emergency landing, the control unit requires the airbag to be inflated, the inflator including for example explosive means or electrical means. 
     In addition, the control unit may include an electrical battery and a changeover switch connected in series to the inflator, the expulsion means being connected electrically to the inflator and to the control unit. 
     Depending on whether a predetermined condition is present or absent, the changeover switch electrically powers or does not electrically power the inflator. 
     In an aspect of an electrical embodiment, the detection means may comprise a sensor for sensing a predetermined event, which sensor is connected electrically to a main switch arranged between the inflator and the expulsion means, the main switch being closed when the predetermined event occurs, a capacitor being connected electrically in parallel with said expulsion means and with the main switch between the inflator and the control unit. 
     In addition, the detection means have, for example, a secondary switch arranged between the control unit and the inflator and co-operating with the detection means. 
     As a result, in the absence of a predetermined event, the main switch is open. If the control unit electrically powers the inflator, the capacitor is charged electrically, while the expulsion means are inhibited. 
     Conversely, if a predetermined event occurs, the main switch is closed. If a secondary switch is present, said secondary switch interrupts the electrical connection going from the control unit to the expulsion means. The expulsion means, e.g. constituted by a solenoid valve, are however driven by being electrically powered by the capacitor. 
     In addition to a protective device as described above, the invention also provides a vehicle seat provided with said protective device. 
     The airbag may then be arranged on a seat harness of said seat. 
     In addition, in a first variant, water detection means may be arranged on the seat, e.g. on the expulsion means for expelling the inflation fluid. 
     In a second variant, with the seat having a seat proper zone and a seat back zone, detection means are mounted remote relative to said zones. 
     For example, on an aircraft, a water detection member of the detection means is disposed in a space liable to fill with water immediately following impact, so as to optimize evacuation of the occupant from the aircraft. 
     Finally, the invention also provides a vehicle including a protective device as described above, in particular an aircraft, and more particularly a rotary-wing aircraft. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The invention and its advantages appear in more detail in the following description of embodiments given by way of non-limiting example, and with reference to the accompanying figures, in which: 
         FIGS. 1 to 6  are diagrams showing a first embodiment; 
         FIG. 7  is a diagram showing a second embodiment; and 
         FIGS. 8 and 9  are section views of expulsion means. 
     
    
    
     Elements that are present in more than one distinct figures bear like references. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a vehicle  1 . The vehicle is not shown distinctly so as not to overcrowd  FIG. 1 . Said vehicle can be an aircraft and in particular a rotary-wing aircraft such as a helicopter. 
     The vehicle  1  is provided with a seat  2  comprising a seat proper zone  3  and a seat back zone  4  for seating an occupant  7 . 
     In order to protect the physical integrity of the occupant under predetermined emergency conditions, the seat  2  has a seat harness  6 . 
     In addition, the vehicle  1  is equipped with a protective device  10  comprising at least one airbag  11  that is inflatable when said emergency conditions occur, e.g. an airbag  11  not provided with a vent and received in a recess in the seat harness  6 . 
     The protective device  10  is then provided with at least one inflation means  12  connected to an airbag  11  via a feed pipe  13 . The inflation means may comprise an inflator  12 ′ proper connected to the airbag via the feed pipe  13 , and a control unit  14  connected to the inflator  12 ′. The control unit  14  comprises usual sensors for determining whether predetermined conditions are satisfied and for instructing the inflator  12 ′ to inflate the airbags  11  when necessary. 
     In addition, the protective device  10  further comprises expulsion means  20  and detection means  15  for detecting a predetermined event, the detection means  15  co-operating with the expulsion means  20  to require deflation of the airbag  11  when a predetermined event occurs. 
     With reference to  FIG. 2 , the inflation means  12  feed the airbag  11  with inflation fluid under predetermined conditions in order to deploy this airbag  11 . For example, on detecting a predetermined condition, the control unit  14  sends an electrical signal to the inflator  12 ′, said inflator  12 ′ then inflating the airbag  11 . It should be noted that the control unit may control a plurality of inflators  12 ′, each inflator being connected via a feed pipe to a respective airbag  11 . 
     The airbags  11  are then deployed out of their recesses to protect the occupant  7 , namely out of the recesses provided in the seat harness  6 , for example. 
     However, if water detection means  15  detect the presence of water, then the expulsion means  20  for deflating an airbag expel the inflation fluid from the airbag  11  in order to make it easier for the occupant  7  to exit to the outside of the vehicle  1 . 
     In order to facilitate expulsion of the inflation fluid from the airbag  11 , each airbag  11  is provided with a peripheral elastic strap  50  exerting pressure on the casing  11 ′ of the airbag  11 . 
     The strap  50  can surround said casing or the face of the airbag  11  that is not in contact with the torso of the occupant  7 , for example. 
     In addition, said strap  50  may be fastened to the ends of the airbag  11  only. 
     It should be noted that the elasticity of the strap  50  ensures the airbag  11  can be inflated. 
     Therefore, while the expulsion means are not connecting the inside of the airbag  11  to the surrounding air, the strap  50  does not hinder inflation of the airbag  11 . Conversely, when the airbag is connected to the surrounding air via the expulsion means  20 , the pressure exerted by the strap on the casing of the airbag causes the airbag  11  to deflate. 
     In another aspect, it should be noted that each expulsion means  20  is arranged on the feed pipe  13  for feeding the inflation fluid, e.g. air, to an airbag. However, it is possible to arrange these expulsion means on the airbag, for example. 
     The expulsion means  20  may comprise an outlet orifice  22  opening out to the outside of the protective device  10  and a moving member  21  such as a piston suitable, for example, for preventing the inflation fluid from passing through the outlet orifice  22  when it is in a first position, and for allowing the inflation fluid to pass through the outlet orifice  22  when it is in a second position. 
     In an electrical first embodiment shown in  FIG. 1 , an electric motor  24  drives the moving member  21  so as to move it from the first position to the second position if water detection means  15  detect the presence of water. For example, the motor  24  then causes an endless screw  24 ′ to turn in order to move the moving member  21  and in order to put the inside of the airbag  11  into communication with the outlet orifice  22 . 
     The expulsion means may also be a solenoid valve of some known type. 
     In this first embodiment, a control unit  14  is provided with a battery  14 ′ and with a changeover switch  14 ″ that is electrically connected to an inflator  12 ′, said inflator  12 ′ being electrically connected to the expulsion means  20  that loop back to the control unit  14 . 
     In addition, the detection means  15  comprise at least one detection sensor  100  for detecting a predetermined event, such as a water presence sensor, a fire detection sensor, or indeed a seat harness opening sensor, the detection sensor  100  being connected electrically to a main switch  110  arranged between the inflator  12 ′ and the expulsion means  20 . 
     In addition, a capacitor  130  is electrically connected in parallel with the expulsion means  20  and with the main switch  110  between the inflator  12 ′ and the control unit  14 . 
     In addition, in the variant shown, the detection means  15  co-operate with a main switch  110  and with a secondary switch  120  arranged between the control unit  14  and the inflator  12 ′. 
     It should be noted that the main switch  110  and the secondary switch  120  can be part of a single switch having two paths. 
       FIGS. 3 to 6  explain how an electrical embodiment operates. 
     With reference to  FIG. 3 , independently of the positions of the main switch  110  and of the secondary switch  120 , the changeover switch  14 ″ is open in the absence of the predetermined conditions. Therefore, the airbag cannot be inflated. 
     With reference to  FIG. 4 , under the predetermined conditions, the changeover switch  14 ″ is closed. However, if the detection means  15  indicate the presence of a predetermined event, e.g. opening of the seat harness, prior to inflation of the airbag, the secondary switch remains open. Therefore, the airbag cannot be inflated. 
     With reference to  FIG. 5 , if the detection means do not detect the occurrence of a predetermined event, then the secondary switch  120  is closed. 
     Whereupon, the inflator  12 ′ is electrically powered and inflates the airbag. 
     In addition, the detection means do not detect the occurrence of a predetermined event, namely, for example, the presence of water, the presence of fire, and opening of a seat harness, subsequently to inflation of the airbag. As a result, the main switch  110  opens. 
     Since the capacitor  130  is being charged, the expulsion means are not driven. 
     With reference to  FIG. 6 , once the airbag has been inflated, and if a predetermined event occurs, the main switch  110  closes and the secondary switch  120  opens. The expulsion means  20  are then electrically powered by the capacitor  130  in order to empty the airbag. 
     It should be noted that the detection means  15  are optionally provided with soluble means for determining the presence of water. These soluble water-detection means  15  may be arranged on the seat, or indeed they may be remote from the seat proper zone  3  and from the seat back zone  4  of the seat in order to detect any entry of water into the vehicle as early as possible. 
     With reference to  FIG. 7 , in a second preferred embodiment, the expulsion means  20  are mechanical means provided with the detection means  15  comprising a water detection member. 
     The protective device then, for example, has a control unit  14  connected via electrical links  12 ″ to one inflator  12 ′ per airbag, each inflator being connected to a respective airbag via a feed pipe  13  such as a feed pipe  13  going, for example, via fastening means  8  for fastening a seat harness  6 , to reach an airbag arranged in said seat harness  6 . In addition, self-contained expulsion means  20  provided with a water detection member are arranged on each feed pipe  13 . 
     With reference to  FIG. 8 , the expulsion means  20  may comprise a T-shaped duct  31 . A first end  31 ′ is then fastened to a first portion  13 ′ of the feed pipe  13 , e.g. by means of spring clipping, a second end  31 ″ being fastened to a second portion  13 ″ of said feed pipe  13 , optionally by means of spring clipping. The third end  31 ″ of the duct  31  projects towards the outside of the feed pipe  13 , said third end being provided with an outlet orifice  22  for removing to the outside EXT the inflation fluid contained in the airbag  11 . 
     In addition, the expulsion means  20  further comprise a stopper  30  fastened to the third end  31 ′″ via a thread  210  or via any equivalent means. This stopper  30  may further include an end wall provided with holes  34 . 
     In addition, the expulsion means  20  further comprise a moving member  21  such as a piston  21 ′ secured to a rod  25 , the rod  25  extending from a first distal segment  25 ′ fastened to the piston towards a second distal segment  25 ″. 
     The moving member, and in particular the piston  31 ′ of said moving member is disposed upstream from the outlet orifice  22 , relative to the direction in which a fluid flows from the feed pipe  13  to said outlet orifice  22 . A gasket  22 ′ is disposed between the moving member  21 ′ and the third end  31 ′″ of the duct  31 . 
     When the moving member  21  is in the first position shown in  FIG. 8 , said moving member prevents fluid from flowing from the feed pipe  13  to the outlet orifice  22 . In addition, it should be noted that the second distal segment  25 ″ comes into abutment against a back seat  35  of the stopper  30  in order to prevent the moving member from moving unduly under the effect of the pressure prevailing in the segment of the duct  31  going from the first end  31 ′ towards the second end  31 ″. 
     In addition, the moving member  21  co-operates with soluble means  15 ′. 
     Thus, the expulsion means  20  further comprise holding means  32  for holding the moving member  21  in the first position under the influence of the soluble means, and for guiding the moving member in its movement from the first position towards a second position. 
     These holding means  32  comprise a plate  37  provided with holes  33 , the plate  37  being wedged between a shoulder of the third end  31 ″ and the stopper  30 . Thus, the outlet orifice  22  is disposed between the plate  37  and the piston  21 ′ situated upstream from said outlet orifice  22 . 
     In addition, the holding means  32  are provided with angularly spaced-apart holding tabs  36  that project from the plate  37 . These holding tabs are then surrounded by the soluble means  15 ′, said soluble means pressing the holding tabs  36  against the second distal segment  25 ″, in particular so as to hold the moving member in the first position shown in  FIG. 8 . 
     Each holding tab  36  is advantageously provided with a holding member  36 ′ co-operating by means of interfering shapes with a holding segment of the second distal segment  25 ″. For example, each holding member  36 ′ comprises a lug co-operating with a notch in a holding segment  26 ′,  26 ″ of the second distal segment  25 ″. It should be noted that the second distal segment  25 ″ may have a first holding segment  26 ′ and a second holding segment  26 ″. 
     Finally a spring is arranged between the plate  37  and the portion of the moving member  21  that prevents fluid from flowing towards the outlet orifice  22 , which portion is the piston  21 ′ in this example. 
     With reference to  FIG. 8 , in the absence of water, the soluble means guarantee contact between the holding members  36 ′ and the first holding segment  26 ′ of the moving member. Said moving member then finds itself in a first position, in which, in particular, it prevents the inflation fluid present in the airbag  11  from escaping via the outlet orifice  22 . 
     Conversely, with reference to  FIG. 9 , in the presence of water, the soluble means  15 ′ are dissolved. In the absence of force exerted by said soluble means on the holding tabs, the spring  200  pushes away the moving member  21  as indicated by arrow F 1 , the holding tabs  36  moving in parallel as indicated by arrows F 2 . 
     When the moving member reaches the second position shown in  FIG. 9 , the holding members  36 ′ can be in engagement with the second holding segment  26 ″ of the moving member. 
     In this position, the inflation fluid of the airbag  11  can escape towards the outside EXT via the outlet orifice  22 , as indicated by arrows F 3 , and optionally via the holes  34  in the stopper that constitute additional outlet orifices. It should be noted that the pressure of the strap on the casing of the airbag facilitates this expulsion of the inflation fluid. 
     Naturally, the present invention may be subject to numerous variations as to its implementation. Although several embodiments are described, it can readily be understood that it is not conceivable to identify exhaustively all possible embodiments. It is naturally possible to replace any of the means described with equivalent means without going beyond the ambit of the present invention.