FIRE EXTINGUISHING SYSTEM FOR AN AIRCRAFT

The invention relates to a system for extinguishing and preventing a fire on board of an aircraft. According to the invention, an aircraft is equipped with an On-Board-Inert Gas Generating-System (OBIGGS) unit comprising a device with an OBIGGS inflow port connected to a source of gas mixture, said gas mixture comprising an inert gas component and an outflow port, said OBIGGS unit being adapted to separate said inert gas component out of said source of gas mixture and to provide said inert gas component to said outflow port, a first connector in fluid connection with said outflow port, a first gas conduit connecting said first connector to said fuel tank for providing said inert gas component to a fuel tank, a second connector in fluid connection with said outflow port and a second gas conduit connecting said second connector to at least one target space selected from the cockpit space, the passenger cabin space, the cargo bay

DETAILED DESCRIPTION OF THE DRAWINGS

Referring first toFIG. 1, an aircraft basically comprises four spaces which are relevant to the invention. In the wings and the region of the wings of the aircraft a plurality of fuel tanks is positioned, one of which is shown in the figure and depicted10. Said fuel tanks may be completely filled before starting of the aircraft but are continuously emptied during flight thus producing an ullage11above the level12of the liquid fuel13. In this ullage gaseous parts of the fuel and oxygen may be present resulting in the risk of fire in the fuel tank.

Further, a cargo bay20axtends along nearly the whole length of the aircraft. This cargo bay is positioned in the lower region of the aircraft and serves to take up luggage of the passengers and cargo goods. Above the cargo bay a passenger cabin30is present which extends along nearly the whole length of the aircraft in the upper region of the hull. In the passenger cabin a plurality of passengers can be seated and facilities for oxygen delivery in case of an emergency are present for each passenger.

Still further, in the front region of the aircraft a cockpit40is present wherein usually two pilots and sometimes additional crew members take place.

A system space50is shown in the nose section of the aircraft. In this system space50number of functional units of the aircraft is accommodated. It is to be understood that the system space50could be positioned in other sections of the aircraft and/or the functional units depicted to be arranged in said system space50could be separated from each other to be accommodated at distant position within the aircraft.

In the system space50an on board inert gas generating system unit60, an on board oxygen generating system70and a fuel cell80is accommodated.

Turning now toFIG. 2, the system space50and the devices accommodated therein are shown in greater detail. The OBIGGS unit60comprises an inflow port61connected to an inflow control unit160. The inflow control unit160comprises three inflow ports161,162,163. The first inflow port161is connected to the fuel cell80and receives oxygen depleted gas from said fuel cell. The second inflow port162is connected to the OBOGS unit70and receives oxygen depleted remainder gas from said OBOGS unit. It is to be understood that the OBOGS unit further comprises an inflow port for bleed air or ambient air and an outflow port for oxygen enriched air but these ports are not depicted in the figure.

The third inflow port163of the inflow control unit160is connected to a bleed air line164supplying bleed air to said inflow control unit.

The inflow control unit160is coupled for signal transmission to the fuel cell80, the OBOGS unit70, the OBIGGS unit60and a control panel (not shown). The control panel allows to switch the inflow control unit in different status. Still further, the inflow control unit is adapted to switch between different status of a number of valve units comprises in the inflow control unit depending on the needs of the OBIGGS unit and the operation of the OBOGS unit and the fuel cell. Generally, the inflow control unit may be switched in a status wherein gas from all three inflow ports is provided to the inflow port of the OBIGGS unit. Depending on the operation of the fuel cell and the OBOGS unit in another status only gas from the first inflow port may be provided to the OBIGGS unit. In a further status only gas from the second inflow port and a still further status only gas from the third inflow port may be provided to the OBIGS unit. Still further, gas from two of the three inflow ports may be provided to the OBIGGS unit in a further status.

The OBIGGS unit further comprises an outflow port62. The outflow port62is connected to an outflow control unit260. The OBIGGS unit provides inert gas to the outflow control unit260. The outflow control unit260comprises four outflow ports261-264. The first outflow port261is connected via a piping to the fuel tank10and permanently fills the ullage above the fuel level with inert gas to prevent an explosive or combustible gas mixture to be present in said ullage. It is to be understood that a plurality of first outflow ports261may be present to selectively provide inert gas to a plurality of fuel tanks or that the piping connecting to the first outflow port of the outflow control unit may be connected to a manifold distributing the inert gas to a plurality of fuel tanks.

The second outflow port262is connected to the cargo bay20. The connection to the cargo bay20is shown as a single piping having an outlet21but it is to be understood that this connection may be designed in such a way to comprise a manifold in said piping and a plurality of outflow ports of said piping into the cargo bay to allow homogenous and quick flooding of the cargo bay with inert gas out of the second outflow port262.

The third outflow port263is connected via a piping to the passenger cabin space. Again, it is to be understood that a plurality of outflow ports31out of said piping into the passenger cabin space may be present although only one such outflow port31is depicted.

The fourth outflow port264is connected via a piping to an outflow port41opening out into to the cockpit space40of the aircraft.

The outflow control unit260is adapted to selectively provide inert gas to the cargo bay20, the passenger cabin space30, the cockpit space40and the fuel tank10. Inert gas may be provided to all these spaces simultaneously or to only one or some of these spaces simultaneously. The control of the inert gas flow to one or more of these spaces can be accomplished by a control panel (not shown) which is positioned in the cockpit space to be actuated by a crew member.

The flow of inert gas to the fuel tanks of the aircraft maybe controlled by the outflow control unit260or may be conducted without control in a permanent supply as a precautionary measure.

Still further, the outflow control unit260is adapted for automatic delivery of inert gas to any of these spaces. To accomplish such automatic delivery, sensor units are coupled for signal transmission to the outflow control unit.

A plurality of cargo bay sensor units22,23are coupled to the outflow control unit260. Further, a plurality of passenger cabin sensor units32and a cockpit sensor unit42is coupled for signal transmission to the outflow control unit260.

Each of the sensor units22,23,32,42comprises a smoke sensor and a temperature sensor for detecting smoke or fire in the region of the cargo bay, passenger cabin or cockpit space where the sensor unit is positioned. Upon detection of such smoke or fire a corresponding signal is transmitted to the outflow control unit and the outflow control unit will activate a valve unit comprised in said outflow control unit to provide inert gas to the space where the smoke or fire has been detected. The outflow control unit may further activate valve units for providing inert to other spaces as a precautionary measure to prevent the smoke or fire from spreading out into these additional spaces.

Each sensor unit further comprises an oxygen sensor for detecting the amount of oxygen present in the region of the sensor unit. The amount of oxygen maybe detected as a concentration of oxygen or a partial oxygen pressure. Each sensor unit provides a signal corresponding to the amount or concentration or partial pressure of oxygen present in the corresponding space. This allows to control the flow of inert gas automatically depending on such oxygen concentration. In particular, the outflow control unit260may provide inert gas to a space until a predetermined level oxygen concentration, oxygen content or partial oxygen pressure in the space has fallen below said predetermined level. The flow of inert gas may then be stopped and be activated in case that the oxygen concentration, partial oxygen pressure or oxygen content again excites said predetermined level.

Generally it is to be understood that in case of providing inert gas to the cockpit space40or the passenger cabin space30the crew members and passengers, respectively, are supplied with oxygen from an emergency oxygen device since the ambient air in said space is depleted from oxygen and does not allow regular breathing out of said space any more.

The outflow control unit260comprises a pressure reservoir for storing inert gas at an elevated pressure. This pressurized reservoir shall usually be filled before operating the aircraft. The continuous flow of inert gas out of the OBIGGS unit60is used to fill said pressurized reservoir with inert gas. The pressurized reservoir allows to release a large amount of inert gas within a short time period into any space of the aircraft in case of an emergency fire or smoke situation. It is to be understood that the continuous flow of inert gas out of the OBIGGS unit may be used to directly supply inert gas to any of the spaces and the quick flow of inert gas out of said pressure reservoir may be used additionally in a bypass arrangement to this continuous flow. The provision of inert gas to the pressure reservoir and the release of said stored inert gas is controlled by valve units comprised in the outflow control unit.