Engine fire extinguisher

Abstract

Engine Fire Extinguisher The invention relates to a fire extinguisher (1) comprising at least: - a body (2) containing a storage chamber (4) and a pressurization chamber (3) separated by a piston (5) adapted to slide within said body (2), an extinguishing agent being present in the storage chamber (4), the storage chamber (4) comprising at least one outlet (10), and - a gas generator (6) adapted to generate a gas in the pressurization chamber (3), the extinguisher (1) being characterized in that the piston (5) comprises a thermal insulation housing (50) in which the gas generator (6) is located, the housing (50) being interposed between the pressurization chamber (3) and the storage chamber (4), the housing (50) opening into the pressurization chamber (3). Figure for the abstract: Fig. 2

Description

Title of invention: Engine fire extinguisher Technical field

[0001] The present invention relates to a fire extinguisher comprising an extinguishing agent. Prior art

[0002] Extinguishing engine fires is a problem encountered particularly in the aeronautical field, for example when trying to extinguish a fire in an aircraft engine.

[0003] Aircraft engine fire extinguishers are generally equipped with systems such as extinguishing agent bottles pressurized to approximately 200 bars. Such systems are kept away from the engine, outside the nacelle. The extinguishers are generally held in position by fixing elements and connected to the engine by hoses, in order to limit the direct exposure of the extinguishers to the high thermal stresses of the engine environment.

[0004] These systems conventionally use a Halon gas as an extinguishing agent that removes oxygen to contain the fire. Halons have the advantage of ensuring satisfactory extinguishing while maintaining a reduced mass. However, Halons are polluting products, which have a high ozone depletion potential (ODP) and whose use is subject to increasingly strict regulatory prohibitions. The use of Halons as an extinguishing agent therefore constitutes a temporary solution that is not environmentally satisfactory and which it is desirable to replace.

[0005] As such, new extinguishing agents have been developed that do not have the harmful effects of Halons. However, these new extinguishing agents require a much greater mass than Halons to achieve the same extinguishing efficiency. Statement of the invention

[0006] The invention relates to a fire extinguisher comprising at least:

[0007] - a body containing a storage chamber and a pressurization chamber separated by a piston capable of sliding in said body, an extinguishing agent being present in the storage chamber, the storage chamber comprising at least one outlet orifice, and

[0008] - a gas generator capable of generating a gas in the pressurization chamber,

[0009] the extinguisher being characterized in that the piston comprises a thermal insulation housing in which the gas generator is present, the housing being interposed between the pressure chamber and the storage chamber, the housing opening into the pressure chamber.

[0010] By placing the gas generator in the piston, the latter is protected by the air or gas present in the pressurization chamber, which acts as a thermal insulator. The gas generator is therefore protected from thermal stresses external to the fire extinguisher by being interposed between a gaseous canopy of the pressurization chamber and the extinguishing agent of the storage chamber. The extinguishing agent has a strong endothermic power, which makes it an excellent thermal insulator. Thus, the extinguisher is very compact, and can be integrated as close as possible to the engine, which makes it possible to limit the number of fixings and pipes required, and thus to lighten the complete device. In particular, such a fire extinguisher placed near the engine is still operational after 15 minutes of fire in the engine.

[0011] According to one embodiment of the invention, the thermal insulation housing defines a projecting portion in the storage chamber and the gas generator is surrounded by the extinguishing agent.

[0012] The housing in which the gas generator is present is in this case insulated on all its faces, thus further improving the resistance of the gas generator in a fire environment.

[0013] According to another embodiment of the invention, the distance between the gas generator and a bottom of the pressurizing chamber is greater than or equal to 0.1 mm. Indeed, preferably, the gas generator must be at a non-zero distance from the bottom(s) of the pressurizing chamber.

[0014] Thus, a thickness of air or gas is retained to protect and thermally insulate the gas generator.

[0015] According to another embodiment of the invention, the gas generator is a pyrotechnic gas generator.

[0016] The use of a pyrotechnic gas generator is advantageous compared to the use of a pressurized gas cylinder in order, on the one hand, to limit the temperature sensitivity of the generated pressure and, on the other hand, to obtain an extinguishing agent pressure profile as a function of time making it possible to obtain extinguishing agent concentration values ​​as a function of time as close as possible to the minimum necessary extinguishing agent concentration values, thus further improving the extinguishing efficiency in the engine environment.

[0017] The invention further relates to an aircraft engine equipped with at least one fire extinguisher as described above.

[0018] According to a particular embodiment of the invention, the engine is an aircraft engine comprising a nacelle, the fire extinguisher being integrated into the nacelle.

[0019] By integrating the extinguisher(s) directly into the nacelle, the number of fixings and pipes necessary to install the fire extinguisher(s). This allows the fire extinguisher(s) described above to be placed as close as possible to the engine.

[0020] The invention also relates to a method for extinguishing a fire in an aircraft engine using at least one fire extinguisher as described above. Brief description of the drawings

[0021] [Fig-1] [Fig.l] is a schematic longitudinal sectional view of an example of fire extinguisher according to the invention inactivated.

[0022] [Fig.2] [Fig.2] is a schematic longitudinal sectional view of the fire extinguisher of [Fig.l] during ejection of the extinguishing agent.

[0023] [Fig.3] [Fig.3] is a schematic longitudinal sectional view of an aircraft engine fitted with fire extinguishers. Description of the embodiments

[0024] Figures 1 and 2 illustrate an example of a fire extinguisher 1 according to the invention. [Fig. 1] illustrates the inactivated fire extinguisher and [Fig. 2] illustrates the fire extinguisher during ejection of the extinguishing agent. The fire extinguisher 1 comprises a body 2 extending along a longitudinal axis X. The body 2 encloses a pressurization chamber 3 and a storage chamber 4. The body 2 also encloses a piston 5, which separates the pressurization chamber 3 and the storage chamber 4. The piston 5 is able to slide in the body 2. The sliding of the piston 5 in the body 2 makes it possible to vary the volume of the pressurization chamber 3 and the storage chamber 4. The piston 5 can slide along a displacement axis which is here collinear with the axis X.

[0025] In the example illustrated in Figures 1 and 2, the body 2 has an internal shape of revolution around the longitudinal axis X, here cylindrical. It is of course not outside the scope of the invention if the body has another geometry of internal shape, provided that the piston has a geometry adapted to that of the body.

[0026] The body 2 comprises a side wall 2a extending along the longitudinal axis X of the body 2 and surrounding the storage chamber 4. The side wall 2a of the body 2 also surrounds the pressurization chamber 3. The piston 5 slides in the body 2 in contact with the side wall 2a of said body 2. The body 2 further comprises a first bottom wall 2b and a second bottom wall 2c. The first and second bottom walls 2b and 2c longitudinally delimit the body 2.

[0027] The first bottom wall 2b delimits the pressurization chamber 3. The second bottom wall 2c delimits the storage chamber 4. The second bottom wall 2c has at least one outlet orifice 10 configured to allow the extinguishing agent to be ejected outside the body 2. The pressurization chamber 3 is therefore located between the piston 5 and the first bottom wall 2b. The storage chamber 4 is located between the second bottom wall 2c and the piston 5. Consequently, the pressurization chamber 3 is delimited by the side wall 2a of the body, by the first bottom wall 2b and by the piston 5. The storage chamber 4 is delimited by the side wall 2a of the body, by the second bottom wall 2c and by the piston 5.

[0028] The piston 5 comprises a first face 51 facing the pressurization chamber 3. The first face 51 of the piston 5 faces the first bottom wall 2b of the body 2. The first face 51 of the piston 5 delimits the pressurization chamber 3. The piston 5 further comprises a second face 52 facing the storage chamber 4. The second face 52 of the piston 5 faces the second bottom wall 2c of the body 2. The second face 52 of the piston 5 delimits the storage chamber 4.

[0029] The piston 5 is configured to sealably separate the pressurization chamber 3 from the storage chamber 4. The piston 5 extends over the entire internal diameter D4 of the storage chamber 4. The piston 5 preferably comprises a sealing system 55 for providing a seal between the pressurization chamber 3 and the storage chamber 4. The sealing system 55 prevents the extinguishing agent from entering the pressurization chamber 3, and prevents air or gases present in the pressurization chamber 3 from entering the storage chamber 4. The sealing system 55 may be a seal arranged continuously between the piston 5 and the body 2, as in the example illustrated in FIGS. 1 and 2.

[0030] The piston 5 may be made of a metallic material, for example aluminum. Advantageously, the piston 5 may be made of a single material in order to simplify the manufacturing process of the fire extinguisher 1.

[0031] A thermal insulation housing 50 is defined in the piston 5. The thermal insulation housing 50 opens into the pressurization chamber 3. Thus, the housing 50 opens onto the first face 51 of the piston 5. The thermal insulation housing 50 is separated from the storage chamber 4 by the second face 52 of the piston 5. The housing 50 does not open into the storage chamber 4. The thermal insulation housing 50 does not open onto the second face 52 of the piston 5.

[0032] A gas generator 6 is present in the thermal insulation housing 50. The gas generator 6 is surrounded by the piston 5, being laterally surrounded by it and having a face located opposite the second face 52 of the piston 5. In the example illustrated in FIGS. 1 and 2, the gas generator 6 is a pyrotechnic gas generator. In a variant not illustrated, the gas generator may be a pressurized gas cartridge. The example of a gas generator 6 illustrated in FIGS. 1 and 2 comprises a pyrotechnic charge 61 known per se. The combustion of the pyrotechnic charge 61 makes it possible to generate a pressurizing gas in the pressure chamber 3.

[0033] The gas generator 6 can be fixed in the piston 5 by a force-fitting. The gas generator 6 can be fixed in the piston 5 by means of third-party elements, for example by means of one or more elastic pins.

[0034] As in the example illustrated in Figures 1 and 2, the gas generator 6 may comprise an initiator 62 making it possible to initiate the combustion of the pyrotechnic charge 61. The initiation of the ignition device leads to the combustion of the pyrotechnic charge and to the release of the gases resulting from the combustion.

[0035] According to one embodiment of the invention, the bottom of the pressurization chamber may comprise one or more connectors. When the fire extinguisher is inactivated, the initiator is connected to said connector by flexible wires capable of transmitting an activation signal sent by the connector(s) to the initiator, said flexible wires being configured to break upon movement of the piston. In this embodiment, when the fire extinguisher is activated by sending an activation signal to the initiator via the flexible wires, movement of the piston away from the bottom of the pressurization chamber causes the flexible wires that connected the initiator to the bottom of the pressurization chamber to break.

[0036] According to another embodiment of the invention, illustrated in Figures 1 and 2, the initiator 62 comprises one or more tabs 63, called "pinoches", extending towards the bottom 2b of the pressurization chamber 3. In this embodiment, the bottom 2b of the pressurization chamber 3 comprises an interface, the tabs 63 of the initiator 62 being configured to be able to be connected to said interface when the fire extinguisher 1 is inactivated. In this embodiment, when the fire extinguisher 1 is activated by sending an activation signal to the initiator 62 via the legs 63 of the initiator 62, and the piston 5 moves away from the bottom 2b of the pressurizing chamber 3, the legs 63 of the initiator 62 are released from the interface by simple translation.

[0037] The activation of the gas generator 6, or more precisely of the initiator 62, can be carried out by an electric current. The activation of the gas generator 6 can be controlled automatically by the aircraft's on-board computer. The activation of the gas generator 6 can be activated manually by the pilot from the cockpit of the aircraft.

[0038] When the fire extinguisher 1 is inactivated, the pressurization chamber 3 has a non-zero volume containing a volume of gas thermally insulating the gas generator 6. Air is preferably present in the pressurization chamber 3. Indeed, the presence of air in the pressurization chamber 3 allows good thermal insulation of the gas generator 6 present in the piston 5. It is of course not outside the scope of the invention if the pressurization chamber 3 has was filled with a gas other than air with lower thermal conductivity.

[0039] The volume of the pressurization chamber 3 when the extinguisher 1 is inactivated is determined so as to obtain a controlled pressure when the gas generator 6 is triggered, in order to ensure satisfactory triggering of said gas generator 6.

[0040] The distance d3 between the first bottom wall 2b of the body 2 and the gas generator 6, that is to say the distance between the gas generator and the wall of the pressurizing chamber 3 opposite the gas generator, may be greater than or equal to 0.1 mm even when the fire extinguisher 1 is inactivated. This distance d3 is measured along the axis of movement of the piston or the longitudinal axis X. Thus, the minimum dimension of the pressurizing chamber 3 along the longitudinal direction X may be greater than or equal to 0.1 mm, even when the fire extinguisher 1 is inactivated. This ensures that there is a sufficiently large thickness of air or insulating gas on the side of the gas generator 6 to improve the insulation of said gas generator 6.The distance between the gas generator and a wall of the pressurization chamber is measured ignoring the presence of flexible wires or lugs providing the connection between the gas generator and the wall(s) of the pressurization chamber.

[0041] An extinguishing agent is present in the storage chamber 4. The extinguishing agent may be present in the liquid state. The extinguishing agent may be present in the gaseous state. The extinguishing agent may be FK-5-1-12 or Novec™ 1230. For example, Novec™ 1230 makes it possible to lower the temperature of the fire in the engine environment by vaporizing at the outlet of the extinguisher and makes it possible to lower the oxygen level. Novec™ 1230 also has the advantage of being dielectric and of not leaving any residue.

[0042] According to a particular embodiment of the invention illustrated in Figures 1 and 2, the piston 5 comprises a projecting portion 52a. The projecting portion 52a is present on the second face 52 of the piston. The projecting portion 52a extends into the storage chamber 4. The projecting portion 52a of the piston 5 is surrounded by the extinguishing agent present in the storage chamber 4. The thermal insulation housing 50 is present at least in part in the projecting portion 52a. Thus, the gas generator 6 is surrounded by the extinguishing agent present in the storage chamber 4. The gas generator 6 is present at least in part in the projecting portion 52a. The gas generator 6 may be mainly, or even entirely, present in the projecting portion 52a of the piston 5. The gas generator 6 may be housed in the thickness of the piston 5, for example without creating any excess thickness, as illustrated in FIGS. 1 and 2.The gas generator 6 is thus isolated on one side by air or gases. present in the pressurization chamber 3, and insulated on the other sides by the extinguishing agent present in the storage chamber 4. The projecting portion 52a may have a circular section, an oblong section or a section of revolution. The shape of the projecting portion 52a is adapted to the dimensions of the thermal insulation housing 50. The dimensions of the thermal insulation housing 50 are preferably adapted so as to remove as much material as possible from the piston 5, in order to obtain a reduced mass extinguisher.

[0043] In the example illustrated in Figures 1 and 2, the projecting portion 52a of the piston 5 is formed by making a groove 52b on the second face 52 of the piston 5, said groove 52b surrounding the gas generator 6. This hollowed-out shape of the piston 5 advantageously makes it possible to lighten it. The groove 52b opens into the storage chamber 4. Extinguishing agent is present in the groove 52b when the extinguisher 1 is inactive. The groove 52b does not open into the pressurization chamber 3. Preferably, the groove 52b is formed so as to produce a secondary projecting portion 52c of the piston 5 around said groove 52b, the secondary projecting portion 52c of the piston 5 being in contact with the side wall 2a of the body 2. This maintains a large contact surface between the piston 5 and the body 2, despite the presence of the groove 52b, which makes it possible to have a sufficient guide length to avoid the piston 5 being buttressed in the body 2.As in the example illustrated in Figures 1 and 2, the sealing device 55 is therefore preferably arranged between the secondary projecting portion 52c of the piston 5 and the side wall 2a of the body 2.

[0044] The piston 5 is configured to communicate to the extinguishing agent present in the storage chamber 4 the pressure imposed by the gas generated by the gas generator 6 in the pressurization chamber 3. The direction of application of the pressure by the piston 5 on the extinguishing agent to be ejected is substantially parallel to the longitudinal axis X of the body 2. The piston 5 is configured not to be broken under the effect of the pressure imposed by the gas generated by the gas generator 6 in the pressurization chamber 3. The gas generator 6 can be configured so as to impose on the extinguishing agent a minimum pressure greater than or equal to 15 bar when cold, that is to say during the activation of the extinguisher 1. The gas generator 6 can be configured so as to impose on the extinguishing agent a maximum pressure less than or equal to 100 bar when hot, that is to say after the activation of the fire extinguisher 1.It is within the general knowledge of the person skilled in the art to design a gas generator allowing the application of the desired maximum and minimum pressure values.

[0045] The extinguisher 1 may further comprise a shutter 11 sealingly closing the outlet orifice 10 and configured to allow the extinguishing agent to exit the body 2 when the pressure in the storage chamber 4 exceeds a predefined value. In other words, the shutter 11 is configured to prevent, when in a first configuration, the exit of the extinguishing agent outside the body 2. The shutter 11 is further configured to move into a second configuration when the pressure in the storage chamber 4 exceeds a predefined value, this second configuration of the shutter 11 allowing the exit of the extinguishing agent outside the body 2. The shutter 11 may, for example, be in the form of a membrane configured to yield when the pressure in the storage chamber 4 exceeds a predefined value. In this case, the shutter 11 may, for example, be a membrane made of aluminum or an Inconel® type alloy.

[0046] The method for dispensing the extinguishing agent will now be described in connection with [Fig. 2]. The gas generator 6 is first actuated in order to pressurize the pressurization chamber 3. This overpressure created in the pressurization chamber 3 is transmitted by the piston 5 to the extinguishing agent present in the storage chamber 4. Once a predefined value has been reached for the pressure in the storage chamber 4, the shutter 11 passes into a second configuration allowing the extinguishing agent to exit the body 2 through the outlet orifice 10. As illustrated in [Fig. 2], the piston 5 is set in motion towards the second bottom wall 2c in order to cause the extinguishing agent to be dispensed. The piston 5 is then set in motion along the longitudinal axis X. The extinguishing agent can be dispensed outside the extinguisher 1.

[0047] During the dispensing of the extinguishing agent, the volume of the pressurizing chamber 3 increases and the volume of the storage chamber 4 decreases. The sum of the volume of the pressurizing chamber 3 and the volume of the storage chamber 4 is constant during the dispensing of the extinguishing agent. The piston 5 is configured to move without deforming during the dispensing of the extinguishing agent. The first face 51 of the piston 5 is subjected to the pressure of the generated gas, this pressure is communicated to the second face 52 of the piston 5 in order to allow the extinguishing agent to be dispensed outside the body 2. In the example illustrated in FIGS. 1 and 2, the piston 5 causes, during its movement, the dispensing of the extinguishing agent outside the body 2 in the manner of a syringe.

[0048] The fire extinguisher 1 is particularly interesting for extinguishing fires in an aircraft engine.

[0049] [Fig. 3] illustrates an example of an aircraft engine 100 comprising fire extinguishers 1 according to the invention. The example of an aircraft engine 100 is a twin-spool, twin-flow aircraft turbomachine comprising, from upstream to downstream, in the direction of flow of the air flow, a fan 200, a low-pressure compressor 300, a high-pressure compressor 400, a combustion chamber 500, a high-pressure turbine 600, and a low-pressure turbine 700. However, the invention may be applied on a turbomachine having a different structure. The primary flow is delimited by an inner casing 800, and the secondary flow is delimited by the inner casing 800 and by an outer casing 900. The outer casing 900 includes the fan casing.

[0050] The fire extinguisher(s) 1 may be arranged on the internal face of the external casing 900, or on the external face of the casing 800, close to the combustion chamber 500 or the compressors 300, 400.

Claims

Claims

1. Fire extinguisher (1) comprising at least: - a body (2) enclosing a storage chamber (4) and a pressurization chamber (3) separated by a piston (5) capable of sliding in said body (2), the piston (5) comprising a face (52) facing the storage chamber (4), an extinguishing agent being present in the storage chamber (4), the storage chamber (4) comprising at least one outlet orifice (10), and - a gas generator (6) capable of generating a gas in the pressurization chamber (3), the extinguisher (1) being characterized in that the piston (5) comprises a thermal insulation housing (50) in which the gas generator (6) is present, the housing (50) being interposed between the pressurization chamber (3) and the storage chamber (4), the housing (50) opening into the pressurization chamber (3),the thermal insulation housing (50) defining a projecting portion (52a) in the storage chamber (4) and the gas generator (6) being surrounded by the extinguishing agent, the projecting portion (52a) being formed by a groove (52b) made on said face (52) of the piston (5), said groove (52b) surrounding the gas generator (6).,

2. A fire extinguisher (1) according to claim 1, wherein the groove (52b) is formed to provide a secondary protruding portion (52c) of the piston (5) around the groove (52b), the secondary protruding portion (52c) being in contact with a side wall of the body (2) surrounding the storage chamber (4).

3. A fire extinguisher (1) according to claim 1 or 2, wherein the distance (d3) between the gas generator (6) and a bottom (2b) of the pressurizing chamber (3) is greater than or equal to 0.1 mm.

4. A fire extinguisher (1) according to any one of claims 1 to 3, wherein the gas generator (6) is a pyrotechnic gas generator.

5. Aircraft engine (100) equipped with at least one fire extinguisher (1) according to any one of claims 1 to 4.

6. An aircraft engine (100) according to claim 5, said engine being an aircraft engine comprising a nacelle, the fire extinguisher (1) being integrated into the nacelle.

7. A method of extinguishing a fire in an aircraft engine (100) using a using at least one fire extinguisher (1) according to any one of claims 1 to 4.

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