DE29921162U1 - Reusable air cushion for occupant protection in aircraft - Google Patents

Description

"Reusable air cushion for the inmate's seat" Dipl.lng.(FH) Sven Rau^ajftier.ljatzi, &zgr;&iacgr;$&bgr;^ filpchenJ^fr 1 -ßgi 1092

Appendix to the application for registration of a utility model

Description of the invention

"Reusable air cushion for occupant protection in aircraft"

Description

The invention formulated in claim 1 is an inflatable gas cushion for aviation, which is intended to protect the occupants from serious injuries caused by impact with the front seats (backrests) or their own extremities in the event of a hard landing (e.g. due to a lack of undercarriage, water landings or landings in forest areas). The system should be designed in such a way that the occupant can leave the wreckage of the aircraft as quickly as possible after the crash landing, before this becomes increasingly impossible due to fire and smoke formation. The system should be as easy to operate as a life jacket. If necessary - and this is usually known in advance in the case of crash landings - this system can be positioned independently by the passenger on their thighs in front of their body, secured to the lap belt or seat and activated on the instructions of the flight crew. Using, for example, CO ₂ cartridges, the gas bag is provided with an internal pressure within a matter of seconds, which is adjusted to the level of average deceleration and the resulting energy input by the occupant.

State of the art:

The state of the art as far as I am aware in the area of passenger protection in civil aviation is as follows:

1. All seats (except those of the flight crew - 4-point belt) are equipped only with a lap belt which is attached to the seat structure.

2. "Normal" pillows with extremely low energy absorption properties are also available to the occupant

3. In the event of a crash landing, passengers should assume one of two possible defined seating positions, which are shown on the safety instructions on the respective boarding passes. The passenger must either bend forward on his knees or support himself on the backrest of the seat in front with his upper arms folded.

4. In a television program called "3 Punkt 12" on the RTL channel on 10.09.99, a two-minute report was broadcast about the protection of aircraft passengers. A system from the Am-Safe company was presented here, which is apparently about to be launched on the market. This inflatable restraint system activates itself

Munich, 29.11.99 :

"Reusable air cushion for passengers^ahutzi Dipl.lng.(FH) Sven Rau'lgaiitierJJatz'i, 8^^%Uippchen,"

at an aircraft deceleration of 16g and positions itself in front of the passenger within a few milliseconds. A battery supplies the accelerometer, which permanently measures the aircraft's decelerations, with power for about five years.

5. A similar concept to that described under 4. was also presented in the magazine Flug Revue, issue September 1999, page 79, by the American company BFGoodrich, which also activates automatically from a deceleration of about 16g and positions itself in front of the occupant within a few milliseconds.

Description of defects

The lap belt used as standard cannot prevent the upper body from rotating forward. Even the prescribed emergency seat positions cannot prevent the occupants from being seriously injured by hard contact with the extremities or structural elements of the aircraft, especially since the backrest stiffness against buckling of today's aircraft seats leaves a lot to be desired (- see RTL film report -). 7 out of 10 crash landings could be survivable today if appropriate precautions were taken, as have been used for years in the automobile industry. Occupants who are injured or have lost consciousness due to hard contact with their heads cannot leave the stationary and perhaps already burning aircraft via the emergency exits at all or can leave it far too late.

Although the airbag modules from Am-Safe and BFGoodrich aim to improve passenger protection, they cannot solve fundamental problems as described below:

1. The provision of an airbag with a volume of around 50 to 60 liters within a few milliseconds, multiplied by the number of seats, would cause excessive stress on the aircraft's pressure dome, meaning that it would not be able to withstand the sudden increase in pressure. The result would be a "tearing" of the fuselage, especially since the additional large transverse forces on the fuselage as a result of the crash landing would significantly reduce the strength of the tubular construction.

2. A sudden increase in pressure inside the aircraft would also represent an extremely high critical stress for the passengers and would be hazardous to their health, perhaps even fatal.

3. A self-igniting system would have to be equipped with a seat occupancy sensor that is automatically deactivated if the seat is not occupied. This would be necessary to avoid unnecessary airbag deployment and thus additional pressure increases in the fuselage.

4. As is known from the experience of airbag technology in the automotive industry, airbag systems that are positioned in front of the occupant within a few milliseconds can pose significant occupant risks in the event of an "out of position"

Munich, 29.11.99 ;

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The systems described by the two companies are of the same size as today's driver airbag systems. It is therefore conceivable that the problems known today with driver airbag systems could be transferred to the planned airbag systems for aircraft.

5. The weight of the restraint systems aimed for by Am-Safe and BFGoodrich is around 700 grams per module. When extrapolated to the respective seats, this weight per module is significantly above the acceptance limit of today's airlines.

6. In the systems described above by Am-Safe and BFGoodrich, the airbag is only triggered when the aircraft decelerates by around 16g. If one considers the inadequate coupling of the occupant via the lap belt, the occupant will begin to rotate forwards at a deceleration of 1g and build up a speed differential to the braked aircraft. According to experience from the automotive industry, triggering only at 16g will be too late to adequately protect the occupant. In particular, the occupant will already be in a forward position in which he will be exposed to the forces of the airbag's deployment. This seating position of the occupant, which can be described as "out of position", will result in additional stress on the occupant. A backward displacement of the occupant in the event of a crash, as described by BFGoodrich, is impossible on the basis of basic physical conditions (F = m x a).

The invention specified in claim 1 is based on the problem of how to significantly increase the occupant protection in aircraft during hard crash landings without causing additional danger to the occupant.

As can be seen from the description of the defects, a functioning restraint system must meet several aspects:

# high kinetic energy of the occupant

# Pressure distribution within a closed tube (aircraft fuselage)

# Energy absorption of the occupant within his maximum possible forward displacement (+ deformation of the aircraft, etc.)

# Consideration of unoccupied individual seats

# Reusability of the airbag system

This problem is solved with the features listed in claim 1.

An embodiment of the invention is explained with reference to Figures 1 to 3. They show:

Fig. 1 the basic scheme of the gas cushion as an "exploded view" Fig. 2 the module in the initial situation before the crash in comparison with and without 3D cushion

Munich, 29.11.99 - >'"

"Reusable air cushion for the
Dipl.lng.(FH) Sven Rau,»!,ajifierjjatz'i,

Fig. 3 the effect of energy absorption in comparison with and without module.

Fig. 1 shows the main components of the module:

An outer shell (1), which is responsible for the three-dimensional shape and the corresponding initial volume, is made from a thin, uncoated PA 66 fabric (e.g. 235dtex). The outer shell (1) also has 2 side openings (5) with a precisely defined diameter through which the gas can escape in the event of intrusion of the upper body and thus energy can be dissipated. The fastening straps (2) are also sewn onto both sides of the outer shell (1), with which the restraint system can be attached to the seat structure, e.g. with carabiners. On the underside of the outer shell (1) in the area of the fastening straps (2) there is a glued and/or sewn reinforcement layer (7) made of a 470dtex PA66 fabric for stability reasons. Here, the outer shell (1), the inner foil (3), the gas cartridge (4) and the assembly platform (8) are assembled and an "ignition cord" is led out of the airbag interior by providing an opening (9) (e.g. slot). All fabric or foil layers are connected together with the gas pressure vessel (4) on the assembly platform (8) in such a way that the leakage from the system is as low as possible. The inner foil (3), which is larger in terms of actual volume than the outer shell (1), is intended to ensure the initial gas tightness and thus the service life of the system. Apart from the generator opening, it has no other openings through which the gas can escape. Because the outer shell (1) has negligible stretch, the inner foil (3) is only subjected to minimal mechanical stress, although a certain internal pressure has already been established by triggering the gas cartridge (4). The gas tightness in the area of the gas cartridge connection and the lead out of the ignition cord can be achieved, for example, by two overlapping layers and their subsequent pressing on the assembly platform. The gas cartridge (4), which can be filled with CO ₂ , for example, must meet two essential system requirements. Firstly, the amount of gas enclosed in the gas pressure vessel is adjusted to the required initial internal pressure in the airbag (including leakage). Secondly, the outlet openings of the gas cartridge must be sized so that the airbag can only inflate within seconds, since the occupant must be protected from violent inflation forces and pressure equalization in the aircraft fuselage must be guaranteed. This long inflation time of the air cushion is possible because the system can be positioned and activated in good time (e.g. 10 to 20 minutes) before the emergency situation.

The mounting platform (8) is designed in such a way that it can clamp all layers of the outer shell (1) and the inner foil (3) with the gas cartridge (4). Since the mounting platform is placed in the pelvic area of the occupant, ergonomic requirements should be taken into account in the design.

Munich, 29.11.99 · · j*

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"Reusable air cushion for passenger protection in aircraft" Dipl.Ing.(FH) Sven RaufLaiftier.IJIgrtz 1, ^0£|^$jJhlfriß24i092

Explanation of how it works:

As described above, when the module is assembled, the inner film (3) lies inside the outer shell (1). If an emergency situation occurs, the passenger will independently position the folded module in front of the pelvis, hook it onto the seat structure on both sides (2) and activate the gas generator (4) using the ignition cord. The airbag's inflation process now begins and should be completed after around 1 to 2 minutes. Within these 2 minutes, the low inflation speed allows the internal pressure within the aircraft fuselage to be adjusted. The airbag volume is predetermined by the size and shape of the outer shell (1) and the amount of gas from the gas cartridge, meaning that the airbag takes on an appropriate internal pressure. This internal pressure (between 0.1 and 0.3 bar) is designed so that the inner film (3), which is not supported by the gas outlet openings (5) on both sides of the outer shell (1), can withstand the loads caused by the internal pressure within these areas. The leakage from the restraint system up to the time of occupant intrusion is negligible due to the sealing measures. The internal pressure within the airbag can therefore be described as constant until the occupant intrusion occurs. If the occupant shifts forwards as a result of the strong deceleration of the aircraft as described in Fig. 3, the airbag is trapped between the thighs, front seat and upper body. This reduces the airbag volume in proportion to the forward displacement. Because the leakage is negligible in this state, the internal pressure will increase accordingly. The load on the inner film in the areas of the gas outlet openings increases proportionally to the internal pressure up to the time at which the inner film gives way to the forces and bursts at at least one opening (5). The trapped gas can now escape from the airbag, limited by the size of the gas outlet opening (5) in the outer shell (1). Only when the gas escapes is the airbag system able to reduce the kinetic energy of the occupant. Since the forward displacement force varies accordingly for different occupants at the same deceleration, one can pre-set the gas outlet openings for the 5th percentile woman, the 50th percentile man and the 95th percentile man as a system optimization approach and take this into account when distributing the protection systems. When the occupant is immersed in the airbag, it must be taken into account that the airbag is still positioned in front of the occupant's head with sufficient residual depth (as shown in Fig. 3), otherwise contact with the top of the skull and structural elements could occur if the occupant is displaced further forward. This must be taken into account in particular if television screens are built into each individual backrest and could splinter if there is violent contact. Additional occupant stress as a result of the increased _CO2 escape can be ruled out.

Munich, 29.11.99 · · ·"

"Reusable Liitkisien' for passenger protection in passenger ships" Dipl.Ing.(FH) Sven Rau? LaiJner^latz 1, §96 _# 8g$4pjichen»gf71-,ß2*1092

What is essential and new about the invention and what advantages does the invention offer over what is known?

1. Provision of a restraint system long before the expected emergency situation

2. Manual positioning, securing and activation of the protective system (see life jacket) on the instructions of the on-board personnel. This means that any loss of comfort can be ruled out.

3. Consideration of the occupant weight through 3 different sized gas outlet openings

4. Long service life (= maintenance of a certain preset internal pressure) through the use of a gas-tight PA film and an uncoated, lightweight outer shell made of PA 66 fabric (e.g. 1 lOdtex to 235dtex)

5. Independent start of gas leakage depending on the respective deceleration of the aircraft by the inner foil bursting when the foil strength at the gas outlet openings is exceeded ("intelligent system")

6. Avoid excessive pressure build-up inside the aircraft fuselage by slowly supplying gas, which is determined by the size of the gas outlet openings on the gas cartridge (inflation time: approximately 1 to 2 minutes)

7. Avoiding airbag-induced injuries due to low inflation forces

8. Avoid hard head contact with one's own extremities or aircraft structures by ensuring a sufficiently large airbag volume and appropriate internal system pressure.

9. Replaceability of the inner foil and the gas cartridge possible after activation

10. Weight of the system between 300 and 400 grams.

11. Calming side effect for the occupant due to the independent positioning of the protection system on the seat, the independent activation of the airbag and the visible protection potential (long standing time) in front of the occupant.

12. Prevention of loss of consciousness of passengers, which enables timely evacuation of the aircraft after an emergency landing.

Munich, 29.11.99 :

Claims (4)

1. Reusable air cushion for the protection of occupants in aircraft, characterized in that 1. that the air cushion is positioned independently by the passenger using fastening straps ( Fig. 1, 2) in front of the pelvis and attached to the seat structure, 2. that the air cushion is automatically activated via the ignition cord on the instruction of the occupant, 3. that the air cushion inflates in front of the occupant within 1 to 2 minutes after activation, 4. that the pre-fill pressure of the air cushion remains almost constant for several minutes until the occupant intrudes, 5. that in the event of the occupant being displaced forwards, the pressure inside the airbag, after reaching a limit value, automatically tears open the inner foil ( Fig. 1 , 3) at the gas outlet holes (Fig. 1, 5) provided in the outer shell ( Fig. 1, 1) and the enclosed gas can escape from the air cushion with the reduction of kinetic energy, 6. that the inner foil ( Fig. 1, 3) and the gas cartridge ( Fig. 1, 4) can be replaced after activation. 2. Air cushion according to claim 1, characterized in that 1. that the air cushion essentially consists of an outer shell ( Fig. 1, 1) (e.g. 235 dtex uncoated PA66 fabric), an inner film ( Fig. 1, 3) and an internal gas cartridge ( Fig. 1, 4), 2. that the outer shell ( Fig. 1, 1), the inner foil ( Fig. 1, 3) and the gas cartridge ( Fig. 1, 4) are assembled on an assembly platform in such a way that the ignition cord of the gas cartridge ( Fig. 1, 4) can be led out from the interior of the airbag, 3. that the leakage through the openings of the inner foil ( Fig. 1, 3) (e.g. overlaps) and the outer shell ( Fig. 1, 1) is kept negligibly small, 4. that holes for gas escape ( Fig. 1, 5) are provided on both sides of the outer shell (Fig . 1, 1), 5. that in the connection area of the assembly platform ( Fig. 1, 8) a reinforcement layer ( Fig. 1, 7) made of the same material as the outer shell ( Fig. 1, 1) is incorporated (e.g. glued or sewn), 6. that a fastening strap ( Fig. 1, 2) is provided on both sides of the outer shell ( Fig. 1, 1) to ensure the position of the airbag in relation to the occupant, 7. that the outer shell ( Fig. 1, 1) provides an opening ( Fig. 1, 9) within the area of the reinforcement layer ( Fig. 1, 7) through which the ignition cord of the gas cartridge ( Fig. 1, 4) can be led out from the interior of the module, 8. that the module. 3. Inner film according to protection claim 1, characterized in 1. that the external dimensions of the film are approximately 10% to 20% larger than the external dimensions of the outer shell ( Fig. 1, 1) to ensure that the film ( Fig. 1, 3) in the initial situation ( Fig. 2) is only subjected to stretching within the gas outlet openings ( Fig. 1, 5) of the outer shell ( Fig. 1, 1), 2. that the connection area of the gas generator and the ignition cord is designed in such a way that, for example, by means of overlapping foil segments, the tightness within the foil is ensured, 3. that the film (e.g. made of polyamide) has a basic strength that can withstand the set initial internal pressure including a double safety factor (e.g. initial internal pressure = 0.25 bar → ensure tear resistance of the film up to 0.5 bar!), 4. that the film tears in the areas of the gas outlet openings in the event of a further increase in pressure due to occupant intrusion, but continues to seal the rest of the outer shell, 5. that the inner film can be replaced after use, but the outer cover can continue to be used. 4. Gas cartridge according to claim 1, characterized in that 1. that the gas escape from the gas cartridge is controlled via the opening cross-sections in such a way that the airbag volume is only fully provided after at least 1-2 seconds, 2. that the escaping gas is insignificantly cooler or warmer than the room temperature.