EP4198932B1 - Device for detecting fires or abnormal excess temperature, energetically independent - Google Patents

Description

The present invention relates to the field of detection and alert devices for the start of fires, or abnormal temperature exceeding.

The present invention relates more specifically to a device for detecting fires or abnormal temperature exceeding, energetically, autonomous, comprising a shape memory component, in particular a shape memory alloy commonly designated under the acronym AMF, in connection with a piezoelectric component.

The combination of the two aforementioned components allows, under certain conditions, in particular temperature, which will be specified below in the description, the generation of an electric current which is extracted in an electric circuit. The resulting electrical signal is perceived by an antenna which in turn transmits in a defined frequency band allowing the sending of an alert to firefighters or fire treatment entities for intervention on the site threatened by the fire or the abnormal temperature exceedance.

The energetically autonomous detection device according to the present invention will find applications, for example but not limited to, in the detection of forest fires, or even in the detection of fires or abnormal temperature exceedances likely to be triggered on sites sensitive industries.

Indeed, with the growing number of forest fires and fires breaking out in Europe and throughout the world, but also because of the risks of explosions on sensitive industrial sites, it is important to act upstream in order to to prevent and contain these fires as much as possible, and to avoid their spread or explosions of dangerous materials.

Fires that occur across the globe cause the loss of thousands of hectares of nature each year. In addition, these fires are accompanied by significant CO ₂ emissions and have a negative impact on the air quality in affected regions. Some fires, of particularly impressive size and intensity, can project plumes or clouds of smoke extending hundreds, or even thousands, of kilometers.

Recent data obtained in particular by the Copernicus program on forest fires show a trend towards their increase in number, as well as an increase in the size of the affected areas, their intensity and their persistence. Regions usually considered to be cold zones, and therefore less conducive to fires, such as Siberia or North America, are no longer spared.

However, once started, certain fires take on such proportions that it is particularly long and complicated to control and overcome them.

It therefore becomes necessary to have an effective preventive arsenal, making it possible to detect as early as possible, from the outset, the outbreak of fires in wooded areas, sometimes remote and difficult to access, in order to control them quickly and efficiently. , in any case, before they get out of control.

In the existing state of the art, there are already numerous fire detection systems.

The French patent document published under number FR 2 614 984 describes an optical system for detecting thermal radiation, intended to detect and locate forest fires in their initial phase, when it is still easy to control the fire. More particularly, it is a device mounted at the top of a mast and whose optical part comprises mirrors, Fresnel lenses or concave mirror collimators, an electromechanical rotation and scanning system and infrared sensors . The latter convert the thermal radiation captured into an electrical signal, which, after software electronic processing, triggers the alarm by radiotelegraphy means.

We also know the French patent FR 2 637 977 which describes a method for detecting a heat source, in particular applicable to the detection of fires, in which a detector device is placed on a support raised relative to the area to be monitored, so that it performs a horizontal scan of it.

This document also describes a station for detecting and locating a fire comprising a source of a small diameter laser beam and, in the path of this emitted beam, return mirror members, a separator device (separator blade or a polarization separator cube), an optical device for polarization variation and convergence, a mirror located in the divergent beam and shaped to collimate the divergent beam received into a parallel beam of relatively large diameter, and an optical assembly. The system, with the exception of the laser source and the mirror, rotates around an X-X axis and directs the outgoing beam so that it scans the area to be monitored.

The French patent FR 2 893 743 describes a forest fire detection method in which a plurality of sensors constitute a mesh of the forest area to be monitored. Each sensor is capable of locally detecting an outbreak of fire, and is associated with a radio frequency transmitter connected to a control terminal, so that the detection of an outbreak of fire near a sensor is automatically transmitted to the control terminal. control, which generates an alert signal, particularly for firefighters.

However, the climatic conditions, the very large surfaces to be monitored, as well as the topography of the places make the configuration of these devices very complicated.

Also note that the devices presented in these documents are based on terrestrial surveillance by cameras or optical and infrared devices which require expensive installations and processing of the information collected by very complex algorithms.

Additionally, fire detection devices based on terrestrial sensor networks, such as the one described in the paper FR 2 893 743 , have the disadvantage of requiring power from chemical batteries, which are not very environmentally friendly because they are not ecological to manufacture, and complicated to recycle. Also note that these batteries require regular maintenance and changing.

We also know of airborne surveillance devices such as drones. However, the effectiveness of these devices depends on the frequency of passage of the machines over the areas to be monitored, which is not optimal.

In order to remedy the aforementioned problems, and in particular those posed by fire detection devices comprising batteries, energy-independent forest fire detection devices have been developed in the state of the art.

In particular, the international patent application published under number WO 2016/151250 describes a device of this type.

This device comprises a shape memory component capable of converting, into displacement and/or change of shape, in other words into mechanical energy, the heat received by a source, the temperature of which is greater than a threshold temperature.

In addition to this shape memory component, the device also includes a piezoelectric component capable of converting the movement and/or change of shape into electrical energy.

The piezoelectric component and the shape memory component are integral.

An electronic module completes the assembly to extract the electrical charges from the piezoelectric component, then to convert the electrical energy produced by this component into a radio signal alerting the start of a fire at a control station.

More particularly, in this detector, a plurality of round wires made of shape memory components, generally designated by the acronym AMF, are integral with a piezoelectric composite, comprising a plurality of piezoelectric cells connected together by electrical conductors. The piezoelectric cells are assembled and fixed between two layers of electrically insulating polymers, which can be of the same or different nature.

The AMF component can also be presented, instead of round wires, in the form of a plurality of flat strips.

The AMF components, round wires or flat strips, are preconditioned at normal room temperature before being positioned on the piezoelectric composite made up of cells assembled between the layers of polymer. In the event of a fire causing a significant increase in the temperature to which the detector is subjected, the AMF components return to their initial shape, by shortening. This results in the release of the pre-stressed piezoelectric element which tends to oscillate around its equilibrium position. This causes a change in the shape of the piezoelectric composite, and causes the generation of an electric current.

The electrical energy is used by the electronic module to emit a radio signal.

Such a detector has the advantage of being energetically autonomous, and therefore of being able to operate without requiring the use of additional energy sources, such as a cell or a battery.

We also know the French patent published under the number FR 3 044 802 , which also describes an energetically autonomous forest fire detection device, of the type comprising an AMF component, this time associated with an electromagnetic coil to produce electrical energy usable by an electronic module, again to emit a radio signal .

The device described in this document more particularly comprises a body in which is arranged an electromagnetic coil comprising a coil of conductive wire connected to an electrical circuit and cooperating with a core made of magnetic material. The core is initially blocked, directly or indirectly, by an AMF component capable of preventing any relative movement of the core relative to the body of the device, in a position outside the coil of conductive wire, when the temperature is below a threshold temperature.

The AMF component, initially constrained, is capable of converting the heat emitted by a rise in temperature above the threshold temperature, into a displacement or a change of shape (it returns to its initial shape) capable of unblocking the core.

The body also incorporates at least one spring capable of relaxing and releasing energy making it possible to propel said core inside the coil of conductive wire when the core is previously unlocked by moving the AMF component.

An electronic module completes the device. This module is capable of converting the electromotive force induced by the movement of the core in the coil into a radio signal warning of the presence of a fire.

However, such detectors can still be improved. They are in fact complex and expensive to manufacture, requiring the presence of numerous elements to be assembled, such as a plurality of wires or strips of AMF components to be manufactured, which must be glued to a piezoelectric composite, itself requiring a complex assembly of piezoelectric cells connected to each other by electrical conductors and sandwiched between layers of insulating polymers.

Furthermore, with respect to magnetostrictive materials, which deform under the action of a varying magnetic field, and in use as mechanical-electrical converters, a time-varying stress is applied to them, in order to 'obtain a magnetic field varying with time. This is then used to produce a current in a coil.

However, these transducers can only generate electrical energy if they are very strongly stressed, that is to say if the force applied is high enough and extends over a long period of time.

Their efficiency is therefore limited, since they generate little energy compared to their dimensions.

However, these materials can generate strong deformations compared to piezoelectrics. This is why piezoelectric-magnetostrictive composites have been developed. In these devices, the significant deformation generated by the magnetostrictive material (under the effect of a magnetic field) generates a strong electric charge at low and high rates of application of mechanical energy thanks to piezoelectrics.

However, this solution requires the application of an external magnetic field, which is not desirable for a fire detector.

The present invention aims to remedy, at least in part, the disadvantages of devices known in the state of the art.

Thus, the present invention relates to a device for detecting fires, or abnormal temperature exceeding, energetically autonomous, in the form of a box inside which is arranged, at least, one memory component of shape capable of converting into mechanical energy, namely into displacement and/or change of shape, the heat received by a source whose temperature is greater than a threshold temperature, at least one piezoelectric component capable of converting the mechanical energy of said shape memory component into electrical energy, and an electronic module capable of converting the electrical energy produced by said piezoelectric component into a radio signal for alerting the start of a fire.

Said device is more particularly characterized in that said shape memory component constitutes, during its movement and/or change of shape, a means of sectioning a support means to which said at least one piezoelectric component is secured, the sectioning of said support means allowing the passage of said at least one piezoelectric component from a first position called "under voltage" to a second position called "free" in which said piezoelectric component is activated and capable of entering into resonance and producing the electrical energy captured by said electronic module.

• ledit composant à mémoire de forme se présente sous la forme d'un manchon cylindrique engagé sur ledit moyen support, ce dernier consistant en un arbre relié audit boitier à l'intérieur de celui-ci, et sur lequel arbre est également solidarisée une lame élastique recouverte au moins en partie d'une couche d'un composant piézoélectrique ;
• ledit composant à mémoire de forme se présente sous la forme d'un manchon cylindrique engagé sur ledit moyen support, ce dernier consistant en un arbre sur lequel sont également solidarisées, de part et d'autre dudit manchon cylindrique, deux lames élastiques recouvertes au moins en partie d'une couche d'un composant piézoélectrique ;
• ledit composant à mémoire de forme est choisi parmi les alliages à base de cuivre CuAIBe, CuAINi et les alliages à base de nickel-titane NiTi, NiTiCu et NitiHf ;
• ledit composant piézoélectrique consiste en du titano-zirconate de plomb ;
• ledit module électronique, apte à convertir l'énergie électrique produite par ledit composant piézoélectrique en un signal radioélectrique d'alerte de départ d'incendie, consiste en un circuit imprimé PCB (Printed Circuit Board) ;
• ledit circuit imprimé est relié à une antenne émettrice du signal radioélectrique.

According to particular embodiments:

• said shape memory component is in the form of a cylindrical sleeve engaged on said support means, the latter consisting of a shaft connected to said housing inside the latter, and on which shaft is also secured an elastic blade covered at least partly with a layer of a piezoelectric component;
• said shape memory component is in the form of a cylindrical sleeve engaged on said support means, the latter consisting of a shaft on which are also secured, on either side of said cylindrical sleeve, two elastic blades covered at least partly a layer of a piezoelectric component;
• said shape memory component is chosen from the copper-based alloys CuAIBe, CuAINi and the nickel-titanium-based alloys NiTi, NiTiCu and NitiHf;
• said piezoelectric component consists of lead titano-zirconate;
• said electronic module, capable of converting the electrical energy produced by said piezoelectric component into a radioelectric fire alert signal, consists of a printed circuit PCB (Printed Circuit Board);
• said printed circuit is connected to an antenna transmitting the radio signal.

The detection device according to the present invention, using shape memory alloys (AMF), has the particular advantage of allowing rapid detection of the start of fires or critical increases in temperature. This rapid detection is made possible thanks to the memory effect of these intelligent materials which are able to change shape with temperature.

The characteristics of the present device also imply that the latter is completely autonomous and in line with the ecological considerations currently sought, since said device does not require any battery for its operation, and depends solely on the material properties of these AMF components.

Other aims and advantages of the present invention will appear during the description which follows relating to embodiments which are given only by way of indicative and non-limiting examples.

• [Fig.1] représente, de manière schématique, le principe général de fonctionnement du dispositif de détection d'incendies ou de dépassement anormal de température, énergétiquement autonome, conforme à l'invention, à savoir une conversion de l'énergie provenant de la chaleur des flammes d'un incendie par ledit dispositif, conduisant finalement à la génération d'un signal radioélectrique.
• [Fig.2] représente, de manière schématique, une vue en coupe transversale d'une première variante de réalisation du dispositif de détection énergétiquement autonome de l'invention, celui-ci comprenant une lame piézoélectrique liée à un arbre support sur lequel est également emmanché un composant AMF, ladite lame piézoélectrique étant dans une position précontrainte dans laquelle elle est désactivée, lorsque le dispositif, et en particulier le composant AMF, n'est pas soumis à une élévation de température due à un déclenchement d'incendie.
• [Fig.3] est une vue similaire à la figure 2, la lame piézoélectrique se présentant toutefois ici dans une position libérée, dans laquelle elle est activée, après sectionnement de l'arbre dû à un allongement et une diminution de diamètre du composant AMF, cette modification de forme résultant d'une élévation de la température au-delà d'une température seuil ;
• [Fig.4] représente, de manière schématique, une vue en coupe transversale d'une deuxième variante de réalisation du dispositif de détection de l'invention celui-ci comprenant deux lames piézoélectriques dans leur position précontrainte dans laquelle elles sont désactivées.
• [Fig.5] est une vue similaire à la figure 4, lesdites lames piézoélectriques étant cette fois dans leur position libérée dans laquelle elles sont activées.
• [Fig.6] illustre schématiquement une vue en perspective du boîtier du dispositif de détection de l'invention, équipé extérieurement d'une antenne et de moyens permettant la fixation dudit dispositif à un élément extérieur quelconque, tel qu'un arbre ou un poteau.
• [Fig.7] est une représentation schématique du fonctionnement du dispositif de détection de l'invention, depuis la détection d'un départ d'incendie dans une forêt, jusqu'à l'alerte, en passant par le traitement du signal émis par ledit dispositif.

Understanding this description will be made easier by referring to the appended drawings in which:

• [ Fig.1 ] represents, schematically, the general principle of operation of the device for detecting fires or abnormal temperature exceeding, energetically autonomous, in accordance with the invention, namely a conversion of the energy coming from the heat of the flames a fire by said device, ultimately leading to the generation of a radio signal.
• [ Fig.2 ] represents, schematically, a cross-sectional view of a first alternative embodiment of the energetically autonomous detection device of the invention, the latter comprising a piezoelectric blade linked to a support shaft on which is also fitted an AMF component , said piezoelectric blade being in a pre-stressed position in which it is deactivated, when the device, and in particular the AMF component, is not subjected to a rise in temperature due to an outbreak of fire.
• [ Fig.3 ] is a view similar to figure 2 , the piezoelectric blade is however presented here in a released position, in which it is activated, after sectioning of the shaft due to an elongation and a reduction in diameter of the AMF component, this change in shape resulting from an increase in temperature beyond a threshold temperature;
• [ Fig.4 ] represents, schematically, a cross-sectional view of a second alternative embodiment of the detection device of the invention, the latter comprising two piezoelectric blades in their pre-stressed position in which they are deactivated.
• [ Fig.5 ] is a view similar to Figure 4 , said piezoelectric blades being this time in their released position in which they are activated.
• [ Fig.6 ] schematically illustrates a perspective view of the housing of the detection device of the invention, equipped externally with an antenna and means allowing said device to be attached to any external element, such as a tree or a post.
• [ Fig.7 ] is a schematic representation of the operation of the detection device of the invention, from the detection of an outbreak of fire in a forest, to the alert, including the processing of the signal emitted by said device.

With reference to the figures of the attached drawings, the present invention relates to a device 1 for detecting fires or abnormal temperature exceeding, which consists of a housing 2. The device 1 of the invention presents, in particular, the characteristic of being energetically autonomous.

Indeed, essentially and particularly advantageously, said detection device 1 according to the invention is based on the principle of energy conversion.

More particularly, with reference to the figure 1 , the heat released, for example, by the triggering of a fire I, in a place where a detection device 1 according to the invention is located, causes an increase in the temperature to which said device 1 is subjected, up to until it exceeds a threshold temperature. Exceeding this threshold temperature results in the actuation of a shape memory component 3, designated below in the description by "AMF component", which said detector 1 comprises, said AMF component 3 transforming the thermal energy received during of the increase in temperature, in mechanical energy.

This AMF component 3 is connected to a system for converting mechanical energy into electrical energy, consisting of a piezoelectric system 4, so that this electrical energy can then be converted, by an electronic module 5, into a radio frequency signal sent to a system terrestrial or satellite detection to alert the start of a fire.

Note that, in the present application, by threshold temperature allowing activation of the AMF component 4, we mean a temperature between 0°C and +250°C, chosen according to the conditions of use and geographical criteria.

It should also be noted that the threshold temperature within the meaning of the present invention is, advantageously, perfectly adaptable since the AMF component 3 included in the detector device 1 according to the invention can have activation temperatures of up to +250 °C.

The threshold temperature considered can, therefore, be adapted according to the use that will be made of the device 1; in fact, this threshold temperature will not be the same depending on whether said detection device 1 of the invention is intended to detect a fire or if it is intended to be installed at sensitive industrial sites within which a temperature relatively high can be considered as not being a sign of a risk of fire.

The AMF component can advantageously consist of a shape memory alloy in particular based on copper (CuAIBe, CuAINi, CuAIMn, CuZnAI), based on nickel-titanium (NiTi, NiTiFe, NiTiCu, NiTiCr, NiTiHf etc.), and the iron-based alloys (FeMnSi, FeMnCr, FeMnCrSi). Some of these shape memory alloys can be monocrystalline, that is to say made up of a single grain, or of several grains separated by grain boundaries with low misorientation.

Preferably, the AMF alloy usable in the manufacture of the fire detector device 1 according to the invention is chosen from CuAIBe, CuAINi, NiTi, NiTiCu, NiTiHf.

Even more preferably, it is the NiTi alloy which is used for the manufacture of the AMF component 3 which comprises the detector device 1 according to the invention.

According to a particularity specific to the detection device 1 of the invention, and as illustrated in the figures 2 to 5 attached, said aforementioned AMF component 3, whose activation temperature is adaptable, is in the form of a sectioning means 31 of a support means 6.

More particularly, as visible in the figures, said sectioning means 31 which the device 1 of the invention comprises is in the form of a cylindrical sleeve engaged on the support means 6 which in turn consists of a shaft 6.

When, due to an outbreak of fire or an abnormal rise in temperature, said sectioning means 31, preferably in the form of a cylindrical sleeve 31, is subjected to a rise in temperature, beyond the threshold temperature, it will lengthen and decrease in diameter, causing the support shaft 6 to break.

At least one piezoelectric component 4 is secured to this support shaft 6. The change in shape of the AMF component, and the resulting sectioning of the cylindrical sleeve 31, are capable of causing the piezoelectric component 4 to pass from a first position called “under tension” or “prestress” 71, illustrated on the figure 2 And 4 , in which said piezoelectric component 4 is deactivated, towards a second position 72 called “free”, visible on the figures 3 And 5 , in which said piezoelectric component 4 is activated.

More particularly, the passage of said at least one piezoelectric component 4 from said first position 71 (inactive piezoelectric) to said second position 72 (active piezoelectric), when the temperature to which the detector 1 is subjected crosses the threshold temperature, allows said piezoelectric component 4 to resonate.

Thus, the mechanical energy which is provided by the movement of the AMF component 3, causing the support arm 6 to break, applies a constraint on the piezoelectric component 4, which passes from one position to another, thus generating an electrical energy of the part of said piezoelectric component 4, in the form of an electric current (or signal).

Indeed, piezoelectric materials are materials that can be described as “intelligent”, to the extent that, under the effect of a constraint applied to them, they are capable of producing an electrical signal.

The piezoelectric materials usable in the context of the present invention to constitute said piezoelectric component 4 can be of different natures, in particular quartz, or a synthetic ceramic such as PZT (Titano-Lead Zirconate).

For the production of the piezoelectric component 4 which equips the device 1 of the invention, we will preferably choose lead titano-zirconate.

Thus, in the present invention, when the movement of the AMF component 3 applies a constraint on the piezoelectric component 4, a current is generated, and extracted in an electrical module 5. The latter is advantageously presented in the form of a printed circuit PCB (Printed Circuit Board).

The electronic module therefore makes it possible to convert the electrical energy produced by the piezoelectric component 4 of the device 1, when it enters into resonance, into a radio signal used to warn and give an alert of the start of a fire, before destruction of the device 1 by flames.

This signal advantageously includes, at least, the geographical coordinates and/or an identification number of the detector 1 making it possible to instantly locate it and, consequently, to determine the location of the fire outbreak.

In a first alternative embodiment of the device 1 for detecting fires or abnormal temperature exceeding according to the invention, now described with reference to the figure 2 And 3 , said shaft 6, on which the AMF component is mounted in the form of a cylindrical sleeve 31, is internally secured to the housing 2.

In this variant, said shaft 6 also supports the piezoelectric component 4 which here consists of an elastic blade 41 covered, at least in part, with a layer 42 of piezoelectric material.

In the original configuration of the fire detection device 1, illustrated on the figure 2 , said support shaft 6 is in one piece. In addition, said elastic blade 41 covered with piezoelectric component 42, is supported, by one of its ends 41a, by this shaft 6, preferably via a ring threaded on said shaft 6. At the level of the second end 41b of the elastic blade 41 opposite said first end 41a, said blade 41 is secured to a frame 8 which advantageously comprises the housing 2.

In this way, the elastic blade 41 which constitutes the piezoelectric component 4 of the device 1 is curved in a first pre-stressed position 71, so that said piezoelectric component 4, in the form of a layer 42 covering said blade 41, is inactivated.

The rise in temperature due, for example but not limited to, to an outbreak of fire, and the passage of the temperature to which the device 1 is subjected beyond the activation threshold temperature of the AMF component 3, results in elongation and reduction in diameter of the cylindrical sleeve 31, which results in the sectioning into two parts 6a and 6b of the support shaft 6 and the passage of the elastic blade 41 covered with the piezoelectric layer 42 in a second "free" position 72 , visible on the Figure 3 in which the piezoelectric component which constitutes layer 42 is activated and enters into resonance producing the electrical signal recovered by the printed circuit PCB 5.

Such an alternative embodiment has the advantage of easier integration of the blade into the housing. In addition, the costs of carrying it out are reduced.

In a second alternative embodiment of the device 1 for detecting fires or detecting abnormal temperature exceedance, described in present in reference to figures 4 And 5 , said shaft 6, on which the AMF component is mounted in the form of a cylindrical sleeve 31, supports, just as in the first variant, the piezoelectric component 4 which now consists of two elastic blades 41', 41" .

Here again, each of these blades 41', 41" is covered, at least in part, with a layer 42', 42" of piezoelectric material.

In this variant, the tensioning of the elastic blades 41' 41" does not require the support shaft 6 to be internally secured to the housing 2 of the device 1, unlike the first alternative embodiment comprising only one blade 41.

As illustrated in the figures, the two elastic blades 41', 41" covered with piezoelectric 42', 42" are each supported by one of their ends 41 a', 41a", via a ring threaded through the level of the support shaft 6. More particularly, said two elastic blades 41', 41" are positioned on either side of the cylindrical sleeve 31 made of AMF component. At the second end 41b', 41b" of the elastic blades 41', 41", opposite said first end 41a', 41a", respectively, said blades 41', 41" are secured to a frame 8 which advantageously comprises the housing 2.

In the original configuration of the detection device 1 according to the invention, illustrated in the Figure 4 , said support shaft 6 is in one piece and the elastic blades 41', 41" which constitute the piezoelectric component 4 of the device 1, are curved in a first pre-stressed position 71, so that said piezoelectric component 4, in the form of a layer 42', 42" covering each of said blades 41', 41", respectively, is inactivated.

Here again, the passage of the temperature to which the device 1 is subjected beyond the activation threshold temperature of the AMF component 3, following the outbreak of a fire, or following an abnormal rise in temperature, results in elongation and reduction in diameter of the cylindrical sleeve 31. This results in the sectioning into two parts 6a and 6b of the support shaft 6, as visible on the figure 5 . The two elastic blades 41', 41" covered with the piezoelectric layer 42', 42" then pass into a second "free" position 72. In this position 72, the piezoelectric component, which constitutes layers 42' and 42" are then activated, and enter into resonance, producing the electrical signal recovered by the printed circuit PCB 5.

Such an alternative embodiment has the advantage of greater initial stability, less effort to generate, and reduced weight.

In a particularly preferential manner, whatever the embodiment chosen for the design of the device 1 for detecting fires or abnormal temperature exceeding according to the invention, the latter comprises an antenna 9, visible on the Figure 6 , connected to the printed circuit 5, and which perceives the electrical signal sent by said circuit 5.

Referring now to the Figure 7 of the attached drawings, said antenna 9 of the detection device 1 of the invention then emits a signal 10 in a defined frequency band. This signal 10 is picked up by a satellite detection system 11 and/or by a terrestrial detection system 12, such as a ground relay antenna, before being transmitted to a unit 13 of a fire processing entity, for example the fire brigade or a control station, for intervention by this entity as soon as possible.

The range of the signal 10 emitted may be from several hundred meters to several hundred kilometers, which also makes it possible to configure an entire network of detectors 1, whatever the configuration of the terrain.

The device 1 for detecting fires or abnormal temperature exceeding according to the present invention has several particularly interesting aspects.

On the one hand, it is inexpensive compared to the investment required to manufacture and install current detectors based on optical systems, or in comparison to setting up aerial surveillance. The present device 1 can, in fact, be simply positioned and secured at the level of a tree, or a stake, for example, through fixing means 14 which are visible on the Figure 6 .

In addition, device 1 has a particularly long lifespan, estimated at more than 40 years, without requiring maintenance once installed, because it is energetically self-sufficient and reliable.

It also results from this “autonomy” aspect, without chemical batteries, a positive aspect from an environmental point of view.

Also note that the response time is fast, estimated between 5 and 30 seconds following the start of a fire, the activation of the AMF component included in said device 1 being almost instantaneous. Such devices according to the invention are therefore particularly effective, without requiring the application of too great a force and/or extending over time.

The detection temperature is adaptable, the detection device 1 being based on AMF components whose activation temperature can be between 45°C and 200°C.

Finally, in comparison with existing fire detection devices based on the use of the properties of AMF components, it is simpler in design and has greater reliability.

Claims (7)

1. An energy-autonomous device (1) for detecting fires or an abnormal temperature exceedance, which device is provided in the form of a housing (2), on the inside of which is arranged at least one shape-memory component (3) capable of converting the heat received from a source, the temperature of which is greater than a threshold temperature, into mechanical energy, namely by movement and/or change of shape, at least one piezoelectric component (4) capable of converting the mechanical energy of said shape-memory component (3) into electrical energy, and an electronic module (5) capable of converting the electrical energy produced by said piezoelectric component (4) into a fire warning radio signal, said device (1) being characterized in that said shape-memory component (3) constitutes, during the movement or change of shape thereof, a means (31) of severing a support means (6) to which said at least one piezoelectric component (4) is secured, the severing of said support means (6) enabling said at least one piezoelectric component (4) to move from a first position (71), referred to as "tensioned", to a second position (72), referred to as "free", in which said piezoelectric component (4) is activated and capable of resonating and producing the electrical energy captured by said electronic module (5).
2. The energy-autonomous device (1) for detecting fires or an abnormal temperature exceedance according to claim 1, characterized in that said shape-memory component (3) is provided in the form of a cylindrical sleeve (31) applied over said support means, the support means consisting of a shaft (6) connected to said housing (2) on the inside thereof, and onto said shaft (6) is also secured an elastic blade (41) covered at least partially by a layer of a piezoelectric component (42).
3. The energy-autonomous device (1) for detecting fires or an abnormal temperature exceedance according to claim 1, characterized in that said shape-memory component (3) is provided in the form of a cylindrical sleeve (31) applied over said support means, the support means consisting of a shaft (6) on which are also secured, on either side of said cylindrical sleeve (31), two elastic blades (41', 41") covered at least partially by a layer of a piezoelectric component (42', 42").
4. The energy-autonomous device (1) for detecting fires or an abnormal temperature exceedance according to any of claims 1 to 3, characterized in that said shape-memory component (3) is selected from copper-based alloys CuAlBe, CuAINi and nickel-titanium-based alloys NiTi, NiTiCu and NitiHf.
5. The energy-autonomous device (1) for detecting fires or an abnormal temperature exceedance according to any of claims 1 to 4, characterized in that said piezoelectric component (4) consists of lead zirconate titanate.
6. The energy-autonomous device (1) for detecting fires or an abnormal temperature exceedance according to any of claims 1 to 5, characterized in that said electronic module (5), which is capable of converting the electrical energy produced by said piezoelectric component (4) into a fire warning radio signal, consists of a printed circuit board PCB.
7. The energy-autonomous device (1) for detecting fires or an abnormal temperature exceedance according to any of claims 1 to 6, characterized in that said printed circuit board (5) is connected to a radio signal transmitter antenna (9).

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