Patent Application
20080038970
a shows a third embodiment of a gas management device according to the invention in a stand-by position.
b shows the gas management device from
a and 8b shows an alternative embodiment of a sleeve for use in connection with the gas management device according to the invention.
The purpose of the invention is, in short, to replace the mechanical function to penetrate and puncture a pressurized vessel, e.g. a sealed opening of a pressurized gas cylinder with a puncture device, e.g. an electrically controlled puncture device without any mechanically movable parts. Prior art uses a sharp object to penetrate the sealed opening, and by replacing it with a pyrotechnical detonator with directional bursting effect arranged adjacent to the sealed opening a large aperture will be created by a chock wave through the sealed opening. The large aperture will allow the pressurized gas contained in the gas cylinder to flow out of the cylinder. The gas management device will thereafter direct the flow of gas into an inflatable unit, such as a life jacket, raft, etc., through a gas channel.
The puncture device 10b comprises a pyrotechnical detonator 16 and a holder 17. Igniting cables 18 are provided through the holder 17 and are connected to an igniting charge 19 of the pyrotechnical detonator 16. The detonator 16 further comprises an explosive charge 15 which is ignited by the igniting charge 19 when an igniting signal is supplied to the igniting cables 18. The holder 17 is attached to the manifold 10a in a suitable manner to create a gas tight seal, e.g. using O-rings and a threaded attachment (not shown). The components, i.e. the igniting charge 19 and the explosive charge 15, of the pyrotechnical detonator 16 are preferably contained within an optional tubular housing, e.g. made out of paper, to direct the bursting effect towards the inlet 11 of the gas management device 10, and to provide a path and directional guidance for the sparks from the igniting charge 19 when igniting the explosive charge 15.
In this embodiment, a gas channel between the inlet 11 and the outlet 12 may be present before the detonator 16 is activated as long as the detonator 16 is positioned a small distance from a closure (not shown) sealing an opening of the pressurized gas cylinder. A stimuli in the shape of an igniting signal is supplied to the igniting cables 18 that will ignite the igniting charge 19 and cause the explosive charge 15 to detonate. A chock wave is created by the detonation that will travel towards the closed opening and puncture the closure. An aperture is thus created in the closure and the gas contained in the cylinder will be released and flow into the manifold 10a. The pressurized gas will thereafter flow through the outlet 12 and inflate the inflatable unit.
If the sensor detects water, the control unit sends an igniting signal (stimuli) via the igniting cables to the puncture device 10b. The sleeve 21 has a tight fit to the detonator 16 and the closure 26, whereby a gas channel is not provided between the inlet 11 and the outlet 12 before the detonator is activated. The gas channel will be created through an area where the explosive charge 15 of the pyrotechnical detonator 16 was situated before activation, and the pressurized gas will flow from the gas cylinder 22 through the sleeve 21 and into the inflatable unit, i.e. the life jacket 23 or life raft (not shown).
a and 3b show cross-sectional views of a third embodiment of a gas management device 30 in a stand-by position and in an activated position, respectively. A gas cylinder 22 being provided with a closure 26 is attached to an inlet 32 of a manifold 31a of the gas management device 30 as previously described in connection with
An outlet 33 to which an inflatable unit (not shown) may be attached is provided in the manifold 31 a close to the region where the closure 26 sealing the opening of the gas cylinder 22 is positioned when attached to the manifold 31. Additionally, a pressure equalizing channel 34 is provided through the manifold 31 a to assist in direct pressurized gas from the gas cylinder 22 to the inflatable unit when the puncture device 31b is activated and the closure 26 is punctured.
The puncture device 31b comprises a detonator 16, comprising an explosive charge 15 and an igniting charge 19, which is arranged within a sleeve 35, and igniting cables 18 are arranged to be connected to a control unit (not shown). The explosive charge 15 of the detonator 16 and a first end of the sleeve 35 are arranged adjacent to the closure 26 before the activation of the detonator, see
b shows a state when the detonator has been activated by the control unit and the explosive charge 15 has exploded, and thereby punctured the closure 26 of the gas cylinder 22. Pressurized gas from the gas cylinder 22 flows out of the gas cylinder, and a force is created that pushes the sleeve 35 towards the second end of the sleeve and compresses the O-rings 36. The pressure equalizing channel 34 reduces the counter force that will act on the sleeve 35 and a gas channel is thus created between the inlet 32 and the outlet 33 through a passage created between the remaining parts of the closure 26 and the first end of the sleeve 35. The gas channel between the gas inlet 32 and the gas outlet 33 is thus circumventing the sleeve 35. The explosive charge 15 is blown to pieces due to the explosion and the sleeve 35, which probably will be deformed by the explosion, will protect the manifold 31a from being damaged.
In the embodiment, a gas channel will then be created between the inlet 42 and the outlet 43 through the area where the explosive charge 15 was positioned before the explosion, through the opening 45 in the sleeve and the space 46 (if present). The position of the opening 45 and the outlet 43 should be selected to ensure that a gas channel will be created when the explosive charge 15 is detonated. In other words, the design of the detonator is critical to ensure proper operation.
In the embodiment, a gas channel will be created between the inlet 52 and the outlet 53 through the area where the explosive charge 15 was positioned before the explosion, around the igniting charge 19 and holder 37 and the cavity 55.
The invention described in connection with
A gas channel will be created between the gas inlet 62 and the gas outlet 63 when the explosive charge is detonated, since the position of the sleeve 64 will be shifted against o-rings provided at the second end of the sleeve 64, whereby the pressurized gas from the vessel 27 circumvent the sleeve 64 and flows through a space 67 provided between the sleeve 64 and the manifold 61 a to the gas outlet 63, which is adapted to be connected to an inflatable unit (not shown), such as a floating device.
In the embodiment, a gas channel will then be created between the inlet 72 and the outlet 73 through the area where the explosive charge 15 was positioned before the explosion, through the opening 75 in the sleeve and the space 78 (if present). The position of the opening 75 and the outlet 73 should be selected to ensure that a gas channel will be created when the explosive charge 15 is detonated. In other words, the design of the detonator is critical to ensure proper operation.
a and 8b show an alternative embodiment of a sleeve 80 used in a gas management device where the pressurized gas is circumventing the sleeve after the closure or casing has been punctured, e.g. the embodiments described in connection with
a shows a side view of the sleeve 80 which is cylindrical and is provided with a first end 81 and a second end 82.
The sleeve described in connection with
Variations in the design of the gas management device are possible within the scope of the claims.
The pyrotechnical detonator 16, 66, 76 is influenced by igniting stimuli, and comprises an igniting charge, such as an electrically activated igniting charge 19, an optical device 69 or a manually activated percussive primer 79. The igniting charge is adapted to generate sparks that will ignite the explosive charge 15. A distance between the igniting charge and the explosive charge 15 is advisable to avoid unintentional activation of the detonator.
The ignition train and sequence of events, as illustrated in
The sparks from this novel composition have a unique capability to directly ignite materials that normally would require a priming layer in order to take fire reliably. Lead azide is such a material that will not reliably take fire from a prior art black powder composition or most hot slag producing compositions. Lead azide will, however, reliably ignite from this novel composition, even when the sparks are guided through a channel for several centimetres. The required composition depends mainly on the physical size of the system, length of the ignition transfer channel and type of acceptor charge. The composition of the ignition donor comprises the following components: A, B, and C, wherein C is optional.
A) Black powder type composition comprising: potassium nitrate (KNO3), charcoal, and optionally sulphur (S).
The potassium nitrate is preferably in the range 50 to 80% by weight, more preferably 60 to 80% by weight, even more preferably 65 to 78% by weight, and is preferably milled, more preferably ball milled into particles.
The charcoal is preferably in the range 15 to 30% by weight, more preferably 15 to 25% by weight, and is preferably, as a non-limiting example, milled and screened to 80 mesh.
The optional sulphur is preferably in the range 0 to 20% by weight, more preferably 0 to 10% by weight, and is preferably milled into particles.
B) Ignition transfer material comprising a Group IV element, preferably Titanium (Ti) or Zirconium (Zr), more preferably Titanium (Ti). The ignition transfer material is preferably provided as: sponge, flake, or powder, having a particle size in the range 25 μm to 500 μm, depending on ignition distance.
The ignition distance is preferably in the range 1 mm to 30 mm, wherein a larger particle size of the ignition transfer material is needed for increasing ignition distance. Too small particles give a flash explosion with the deflagration being too fast to achieve dependable ignition and too large particles do not burn well. The optimum particle size for a particular geometry of the detonator will emit particles that will hit the acceptor charge while still burning as a mixture of the metal and its oxides. These particles will have extremely good heat transfer properties, and do not just bounce off the surface they hit, as sparks generally tend to do.
C) Optional binder, which preferably comprises: nitrocellulose (NC), stabilizer, plasticiser, phlegmatizer, and solvent.
The nitrocellulose comprises nitrogen preferably in the range 12 to 13% by weight, more preferably close to 12.6% by weight.
The stabilizer is preferably urea which preferably is provided in small quantities, e.g. in the range 0 to 1% in weight.
The plasticiser and phlegmatizer is preferably camphor, which preferably is provided in the range 0 to 30% in weight.
The solvent is preferably acetone, preferably well dried. MEK (Methyl Ethyl Ketone), and a number of organic esters such as isoamylacetate are other possible solvents in order to adjust the drying rate to suit the process.
The optional binder may also be used to regulate the burning rate of the composition. It may also be used to reduce the amount of dust during production of a granulated composition
A preferred composition for the donor charge (igniting charge) is as follows:
A) 80% by weight, and
B) 20% by weight.
wherein
A) comprises KNO3 75% by weight, S 10% by weight, and Charcoal 15% by weight, mixed together in a suitable process, e.g. screen mixed 3 times through 40 mesh.
B) comprises Ti sponge with particle size of 100 μm
Optionally, the above described composition may be diluted by C) comprising NC thinned with acetone to proper dipping rheology to an extent that the component C constitutes up to 10% by weight of the final composition. With the composition including component C it is possible to get a dipping rheology similar to prior art production of matches where animal hide glue is used as the binder.
The above described material has similar properties as achieved with hide glue. The dipped igniters come out nicely drop shaped and dry hard. This is difficult to achieve with most of the metal powder and oxidizer combinations well known as igniters. The black powder type composition lowers ignition temperature in order to create a single dip system. Most commercial matches use 2 or 3 dips with a sensitive first fire layer and successive output charge layers to produce molten slag and sparks.
If a first sensitizer dip is necessary, as in very low current electric bridge wire igniters or optical igniters used as ignition stimuli, then the black powder type composition should preferably be sulphurless. 70% KNO3 and 30% Charcoal works well as component A. The reason for this is the incompability of sulphur with the chlorates usually used in such sensitive igniters.
The preferred distance between donor charge and the acceptor charge is 10 mm. The width of the channel is 1 to 5 mm with the preferred diameter being 2 mm. The ignition channel can be curved, s shaped or some other complex geometry.
The lead azide acceptor charge is preferably a type that has a short deflagration to detonation transition, DDT, after ignition of the acceptor charge. This depends a lot on the type of co-precipitants used and on the exact process parameters used in the production of the lead azide. Silver azide is another possible material that has a very short DDT. Thus lead and silver azide are two examples of suitable acceptor charges that can be used according to the invention. Other materials having a corresponding short DDT can also be used.
The preferred device consists of an aluminium cylinder with a 2 mm hole axially through its centreline. The acceptor output charge end of the cylinder comprises e.g. 20 mg of lead azide pressed into a small pellet. The spark producing donor charge is placed in the opposing end of the hole and sealed in. This arrangement is similar to what is well known from prior art as seen in electric basting caps, which usually contain a commercial electric match head and a very sensitive receptor charge to transfer fire to the output charge, usually lead azide and pentaerythritol tretranitrate (PETN). However, the present invention does not need a sensitive receptor charge in this configuration, as is common in the prior art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0601599-4 | Jul 2006 | SE | national |
