Field of the Invention [001] Invention relates to a fire suppressing or extinguishing devices, especially to the fire suppressing gas-generating devices.

Background of the Invention [002] Fire suppressing gas-generating devices are used to suppress fires in enclosed volumes, such as automobiles, planes, ships, server rooms, buildings, etc. Vehicles are subjected to vibrations, which puts higher demands for stability and long term use or shelf life for gas- generating devices. Therefore, it is necessary to design a fire suppressing gas-generating device, which can withstand vibrations without losing its performance.

[003] United States patent publication No. 7,832,493 discloses a fire suppression device including a fire suppression agent generator. The device comprises a trigger adapted to initiate generation of the fire suppression agent from the fire suppression agent generator. A container at least partially surrounds the fire suppression agent generator and the trigger, the container includes a discharge port that directs fire suppression agent in at least two opposed directions. In one example, the discharge port extends substantially around a perimeter of the container.

[004] International patent application publication No. WO 2011/041879 discloses a fire suppressing gas generator, that comprises a cylindrical housing comprising an array of discharge ports distributed generally uniformly therearound; a cylindrical filter disposed within the housing and spaced from the interior wall of the housing; a plurality of azide-based propellant grains inside the cylindrical filter; and at least one ignition device associated with the propellant grains. The propellant grains when ignited by the ignition device generate a fire suppressing gas which passes through the filter and out of the discharge ports of the cylindrical housing for delivery outside from the housing into environment to be suppressed.

[005] United States patent application publication No. 2010/0307775 discloses a gas generating device with grain-retention structures. In particular, the gas generating device has at least one retention structure fixed to a frame and positioned between adjacent gas generating grains arranged in a longitudinal stack. Said device has plurality of elements, which makes manufacturing process complicated, especially in assembling.

[006] Moreover, above-mentioned devices does not provide effective means nor for withstanding environment vibrations nor for improving easiness of assembling.

Summary of the Invention

[007] The aim of invention is to design a gas generating device, which is reliable in long term and easy to manufacture, especially to assemble.

[008] Present invention is a fire suppressing gas-generating device comprising a housing, a plurality of gas-generating grains disposed within the housing, a multi-layer filter disposed between the gas generating grains and the housing, an ignition device associated with gas generating grains, and a foil covering discharge openings made in the housing.

[009] The housing itself can be as a tube (circular cross-section) or as a rectangular (rectangular cross-section). The housing comprises an array of discharge openings distributed generally uniformly therearound or around the perimeter of the housing. Distribution of discharge openings can form different grids or configurations. In one embodiment, discharge openings can be distributed in a chess-like configuration, but in another embodiment, the discharge openings can be distributed in equal rows and/or columns. In another embodiment, the discharge opening may be in the form of a star or triangle. [010] The housing is closed from both sides by ends caps. The end caps are sealed against the housing so that no gas flow is possible through them. The caps can be fitted tight onto the ends of the housing. In another embodiment, the ends of housing are roll formed over the caps. The caps also form an end sealing for the filter in order to eliminate any gas flow through the open parts of the filter. Additionally, the caps and the hosing is secured to each other by means of adhesive. For example, the caps are attached to the housing using an adhesive and in the next step the same attachment is roll formed increasing the reliability of the connection. In another embodiment the end cap is secured at the housing by means of laser welding and the welding seam is annular welding seam between the end cap and the housing. The number of welding seams depends on a power and/or dimensions of the fire suppressing gas generating device. [Oi l] The multi-layer filter encompasses said plurality of gas-generating grains. The multilayer filter itself is disposed between the gas generating grains and the housing. Moreover, the multi-layer filter on its inner surface has at least two, preferably three, bumps extending axially along entire length of the inner surface of the multi-layer filter and radially towards the gas generating grains so that the bumps are in the contact with the gas generating grains and constrain a movement of the gas generating grains relative to the housing and to each other. The bumps of the filter is secured against said gas-generating grains in such way the bumps constrains a movement of the gas generating grains relative to the housing and to the each other.

[012] The multi-layer filter comprises at least one layer of steel mesh, at least one layer of steel wool and at least one layer of Si02 felt. Si02 felt is more heat resistant than many prior art materials as well as Si02 provides improved filtering capabilities. In another embodiment the multi-layer filter sequentially comprises a layer of steel mesh, preferably steel mesh 24, another layer of steel mesh, a layer of steel mesh and two layers of steel wool, another layer of steel mesh and a layer of steel wool, and another layer of steel mesh followed by three layers of Si02 felt and three layers of the steel mesh. The layer of Si02 felt functions as filtering layer reducing contamination of the environment. Moreover, the Si02 is resistant to heat. In another embodiment a layer of A103-Si02 felt may be used instead of layer of Si02 felt. In another embodiment a combination of the layer of A103-Si02 felt and the layer of Si02 felt may be used. Aforementioned layers may be combined to comply with necessary needs for filtering and heat absorbtion. [013] The bumps of the multi-layer filter are produced by roll forming layers of said multilayer filter. The recesses are created in the roller of the roll-former, wherein in the process of manufacture of the filter by the roll forming the first two to three layers take over a shape of the recess in the roller. The first two to three inner layers of the filter are layers of steel mesh. The steel material is easy material for shaping in order to create bumps or bosses. The bumps may be created by any other shaping process.

[014] The end cap has a first annular bent and a second annular bent. The second annular bent forms annular recess between the end cap and the inner surface of the housing and the width of the annular recess in radial direction is such that the one end of the multi-layer filter can be inserted and secured against the free movement. The end cap may be formed by drawing, pressing or roll forming.

[015] A plurality of gas generating grains are disposed within the housing. The grain is known as a gas generating material having a cylindrically shaped body. The shape and amount of gas generating grains depend on performance requirements for the fire suppressing gas-generating device. The housing, filter and discharge opening size and shape can be adapted to the necessary requirements. For example, server rooms require fire suppressing devices which can be situated in rectangular space. Accordingly, the device can comprise a housing with rectangular cross section comprising an array of discharge openings having inwards bent flanges and distributed generally uniformly around the perimeter, wherein at least two stacks of gas generating grains are disposed and filter is disposed between the housing and gas generating grains as well as a spacer may be disposed between the stacks of the gas generating grains.

[016] A composition of gas-generating grain comprises a guanidine nitrate, basic copper nitrate and an additive. The gas generating grain can further comprise a fuel for enhancing ignition process. [017] The ignition device is associated with the gas-generating grains for ignition of said the gas-generating grains. The ignition device further comprises a fire guide to increase ignition. The igniting device may further comprise ignition enhancing elements for sustaining ignition and following burn of the gas generating grains. In another embodiment, the ignition device further comprises a powder ring that is disposed so that the powder ring faces or is in contact with the gas-generating grain. The ring is made of fast burning powder. The aim of the powder ring is to provide additional security for the device in case of a fire during transportation of the device or in a ware house. In case of fire during transportation the fast burning powder ring ignites from the generated heat and in a result ignites also the gas-generating grains. The device is activated and it generates fire suppressing gas. In the meantime, the device has been worked and further accidental burning is prevented.

[018] The filter encompasses gas generating grains and can be disposed between the gas- generating grains and the housing in order to filter generated gases. In other embodiment, a spacer may be arranged between the gas generating grains or stacks or columns. In another embodiment a leaf spring may be inserted between the two gas-generating grains or between the gas-generating grain and the end cap such that axial movement of the gas-generating grains is reduced or eliminated. [019] The device further comprises the foil or foil section disposed on the outer surface of the housing such that the foil covers the discharge openings. Therefore, covering and protecting the interior of the housing from the environment. The foil section arrangement on the outer surface of the housing further improves assembly of said device, because the foil section does not interfere with other elements of the device. The foil is selectively disposed only on discharge opening to cover and protect the interior of the housing from the environment. The foil is attached to the outer surface of the housing by means of adhesive in such way that upon exposure to heat, which is generated from ignition of the gas generating grains, the adhesive weakens to allow separation of the foil from the housing to allow an outflow of generated gas through the discharge opening. The foil is selected from the group of the following metals: aluminium; copper and tin. The foil preferably is aluminium foil. In another embodiment each discharge opening is provided with a separate foil section.

[020] The fire suppressing gas-generating device further comprises a casing enclosing the housing, wherein an inner diameter of the casing is larger than an outer diameter of the housing such that a gap is created therebetween. The casing is connected to the housing through a gasket defining a gap between the casing and the housing. The gasket serves a connecting and dampening part. The gasket dampens the shock in case the device is dropped or influenced by any other outer mechanical action. The gasket together with the casing improves a protection of the device, especially further covering and protecting from the environment, as well as allowing the device withstand vibration without losing its performance.. The casing further comprises an end cover on each side thereof, enclosing both ends of the casing. A bracket is attached to each end cover, thereby providing attachment points for the device. Accordingly, the device may be attached to any surface by means of said brackets and brackets shape may be modified to comply with necessary installation requirements.

[021] The casing comprises at least one layer of steel mesh and a layer of Si02 felt. In another embodiment the casing comprises a layer of Sio2 felt enclosed from both sides with a layer of steel mesh. The layers of steel mesh providing mechanical strength of stiffness and layer of Si02 felt functions as a filter. [022] The fire suppressing gas generating device fulfils higher demands for stability and long term use or shelf life for gas generating devices in unfavourable environments having negative external factors. Brief Description of the Drawings

[023] The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments of the invention.

[024] Fig. 1 is a perspective view of one embodiment of a fire suppressing gas-generating device without a casing 10.

[025] Fig. 2 is a longitudinal cross-sectional view of a fire suppressing gas-generating device showed in Fig. 1. A foil 7 is taken off from one row of discharge openings 2 for clarity of understanding.

[026] Fig. 3 is a transversal cross-sectional view of a fire suppressing gas-generating device showed in Fig. 1.

[027] Fig. 4 is a perspective view of one embodiment of a fire suppressing gas-generating device with a casing 10.

[028] Fig. 5 is a longitudinal cross-sectional view of a fire suppressing gas-generating device showed in Fig.

[029] Fig. 6 is a transversal cross-sectional view of a fire suppressing gas-generating device showed in Fig. 4.

Detailed Description of the Invention [030] A fire suppressing gas-generating device according to an embodiment is shown in Figs 1 to 3. The gas-generating device comprises a housing 1 having circular cross-section. The housing 1 comprises an array of discharge openings 2 distributed generally around a perimeter of the housing 1. The discharge openings 2 are covered by the foil section 7 in a shape of a strip. The device further comprises an end cap 3 on each end of the housing 1.

[031] A plurality of gas-generating grains 4 are disposed in a stacked relationship within the housing 1 (see Fig. 2). The grains are made of guanidine nitrate, basic copper nitrate and a binder. The grains 4 may also have a fuel for enhancing ignition. The gas generating grains 4 are stacked in one column. It may also comprises a retention structure or auxiliary filter (not shown in Figs) disposed between each gas generating grain 4.

[032] The gas generating device further comprises a multi-layer filter 5 encompassing said plurality of gas generating grains 4. The multi-layer filter 5 is disposed between the gas- generating grains 4 and the housing 1 (see Figs 2 and 3). The multi-layer filter on its inner surface has three bumps 55 extending axially along entire length of the inner surface of the multi-layer filter and radially towards the gas generating grains so that the bumps 55 are in the contact with the gas generating grains 4 and constrain a movement of the gas generating grains 4 relative to the housing 1 and to each other. The following feature increases reliability of the device. The device can withstand vibrations for a much longer time than other designs. The multi-layer filter 5 comprises at least one layer of steel mesh, at least one layer of steel wool and at least one layer of Si02 felt. For ease of understanding the multi layer filter 5 is illustrated in Figs as one piece element.

[033] The device further comprises an ignition device 6 associated with the gas-generating grains 4 for ignition of said the gas-generating grains 4. The igniting device 6 may comprise further ignition enhancing elements (not shown in Figs) to sustain ignition and following burn of the gas generating grains 4. The ignition device 6 further comprises a fast burning powder ring 12 that is disposed so that the fast burning powder ring 12 faces or is in contact with the gas-generating grain 4 (see Figs. 2 and 5).

[034] The discharge openings 2 are covered by the foil section 7, preferably aluminium foil section 7. The foil 7 is attached to the outer surface of the housing 1 by means of adhesive 9 in such way that during stand by or shelf life the foil section 7 securely seals the interior of the housing 1, but upon exposure to heat from ignition of the gas generating grains 4, the adhesive 9 weakens and separates from the outer surface of housing 1 under pressure from the generated gas allowing to escape said gas to suppress the fire. The foil section 7 in the form of strips. The foil 7 covers discharge openings 2 sealing said gas generating grains 2 from the environment. The foil 7 is attached to the housing by means of adhesive 9, which weakens under higher temperatures, for example, upon reaching 150 degrees Celsius. In a result, a gas generated during ignition and burning process can easily escape the device into environment. The following configuration of the foil 7 reduces complexity of assembling and control of sealing. [035] The end cap 3 of the device has a first annular bent 31 and a second annular bent 32, wherein the second annular bent 32 forms annular recess between the end cap 3 and the inner surface of the housing 1 and the width of the annular recess in radial direction is such that the one end of the multi-layer filter 5 can be inserted and secured against the free movement (see Figs 1, 2 and 5). The end cap 3 is secured at the housing 1 by means of laser welding and the welding seam is annular welding seam between the end cap 3 and the housing 1.

[036] The fire suppressing gas-generating device further comprises a casing 10 enclosing the housing 1, wherein an inner diameter of the casing 10 is larger than an outer diameter of the housing 1 such that a gap 8 is created therebetween (see Figs. 4 to 6). The casing 10 is connected to the housing 1 through a gasket 11 defining a gap 8 between the casing 10 and the housing 1. The casing 10 further comprises an end cover 13 on each side thereof, enclosing both ends of the casing 10. The casing 10 further comprises a bracket 14 that is attached to each end cover 13 providing necessary attachment point for installation of the device.

[037] The casing 10 comprises a layer of Sio2 felt 102 enclosed from both sides with a layer of steel mesh 101. The following structure provides mechanical stability (stiffness) to the device as well as protecting the device from mechanical shocks. The Si02 felt functions as a filter element.

[038] While the invention may be susceptible to various modifications and alternative forms, specific embodiments of which have been shown by way of example in the figures and have been described in detail herein, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention includes all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the following claims.

List of references used

[039]

1 - a housing;

2 - a discharge opening;

3 - an end cap;

31 - a first annular bent of the end cap;

32 - a second annular bent of the end cap 4 - a gas generating grain;

5 - a multi-layer filter;

55 - a bump of a multi -layer filter;

6 - an ignition device;

6A - an ignitor;

7 - a foil section;

8 - a gap;

9 - an adhesive;

10 - a casing;

101 - a layer of steel mesh;

102 - a layer of Si02 felt;

11 - a gasket;

12 - a powder ring;

13 - an end cover; and

14 - a bracket.