Patent Application
20170219328
This application is a U.S. national stage application of a PCT application PCT/RU2015/000074 filed on 5 Feb. 2015, whose disclosure is incorporated herein in its entirety by reference, which PCT application claims priority of a Russian Federation patent application RU2014104146 filed on 6 Feb. 2014.
The invention relates to non-electric initiation devices which convert the initial mechanical impulse into fire power or induce explosive transformation which can be used for the ignition of explosives, munitions, military shells or various pyrotechnical devices, i.e. any tools of controlled explosion or ignition.
Initiation devices are tools and instruments started by simple initial impulses that initiate explosive transformation (combustion or detonation) of gunpowder or explosives (Bubnov P. F., Sukhov I. P./Initiation devices//Moscow, OBORONGIZ, 1945, p. 4).
The conventional initiation devices used for conflagration or detonation induction of explosives are primers used in impact-based inlets or impact-based tubes, priming tubes, vent sealing tubes, detonating caps. These devices are initiated by mechanical, e.g., impact-based, impact or friction impulse. A mechanism consisting of impact-based primer and impact-based device is called mechanical igniter, while the one consisting of a primer and a friction device is called friction igniter.
In the documents of this application, an ‘igniter’ is any mechanism performing ignition function in pyrotechnical or explosive devices.
The impact igniters commonly use impact-based or detonating caps as initiation device. Caps are typically installed in the immediate vicinity of an explosive or pyrotechnical charge [1] or at some distance (through a detonating cord) [2, 3].
The friction type fuses typically use friction primers where the ignition is started by the movement of a particular tool (scratcher) within the igniting compound [4, 5] or within the friction ignition unit with a slow match by pulling the cord [6].
Common practice is to use fuses with friction igniters with red phosphorus-based compound which does not require significant force or metal parts in the igniter mechanism. The red phosphorus-based fuses are unreliable, excessively sensitive, hygroscopic and unsafe. Phosphorus-free friction igniters require metal parts in the ignition mechanism and significant driving forces due to their lower sensitivity. Such fuses have limited shelf life because of the hygroscopicity of the used compounds and the corrosion of the metal parts.
The design of initiation devices is defined by their application area. Even the igniters of the same type can have different main details which are non-interchangeable.
The main goal of the present invention is to develop a safe and reliable compact initiation device which can be used for initiation of various explosives and pyrotechnical systems.
The following technical result is achieved by this invention:
This technical result is achieved by designing the initiation device as a unit with an end-to-end axial channel. It is used as an insert or is integrated into the case of an igniter, a shell or a pyrotechnical device.
As in the known solutions, the initiation device described in this invention is intended to receive a starting mechanical impulse of impact-based, impact or friction type and transform it into a flame impulse.
The known solutions use holes in the thin cap walls to transmit the impulse in a certain direction (impact-based, impact types) or to create it (friction type). Unlike the known solutions, this invention uses an end-to-end axial channel to create the directed flame impulse. Moving along the channel from the initiation spot, the impulse is transmitted to the pyrotechnical, explosive or combustible material or compound.
So the initiation device combines the functions of an element receiving the starting impulse and transforming it into flame and of an element transmitting the flame impulse to the charge being ignited. Thus, the invention can fully execute the function of commonly known non-electric initiation devices, in particular, the primers, which allows substituting them in these applications.
An element (‘anvil’) is a sizable one-piece or composite element designed to be coaxially locked as an insert in the igniter, munition or shell casing. If the element is integrated into the casing of an igniter, munition or shell during its manufacturing, the element is an integral part of the casing being the neck (converging casing walls in the cross-section) which forms the axial channel.
The external anvil design mimics the internal casing design of an igniter or shell. As igniters and shells are typically tube-shaped, the element is usually meant to be designed in cylindrical shape. However, other element shapes are also viable because this does not affect its functioning and performance.
Various initiation device designs, which correspond to the variety of possible applications, are described here below.
The element channel is straight or cone-shaped in the axial section, i.e. it has the shape of a funnel, preferably round or rectangular in the cross-section. Channel walls can be curved inwards (tapered funnel shape). On the inside, the channel walls can be smooth, rough or corrugated. As the main element function is the formation and transmission of the flame impulse, the axial channel is the ‘ignition channel’.
A collar can be made around the channel entrance (from the side receiving the initial impulse).
The anvil can have at least one end-to-end slit aperture (diametrical or radial) intersecting the channel and/or at least one through hole between the channel and the element side wall, which functions as vent channel. The channel walls can also be perforated. The slit aperture opens under the initial impulse pressure thus damping it and transforming it into friction force. Excessive gases are removed from the channel through the slit (or hole), thus stabilizing the combustion conditions of the ignition compound.
The initiation device can be made of polymer, metal or composite material such as fiberglass or combustible material.
Ignition compound (IC) is placed into the channel.
IC can be coated onto the end-to-end channel walls, pressed into the channel, placed at the channel entrance as an initiating compound drop, or placed in the channel by using a combination of these methods. Other methods ensuring the secure retention of the ignition compound within the channel are also acceptable.
Impact-based initiating compounds, pyrotechnical ignition compounds, friction compounds or their combinations can be used as ignition compound.
Alternatively, a primer can be installed above the element channel (e.g., supported by the collar).
On the initial impulse receiving side, the element is sealed with a film, membrane, foil or lacquer over the compound, which protects the compound from the environment, securing it and extending its service life.
Unlike the commonly used technical devices, the suggested initiation device is not bound to a specific application mechanism, which makes it versatile.
Another object of this invention is an igniter containing the described initiation device.
In case of a compact-based initiation mechanism, the igniter contains an impact-based mechanism consisting of a hammer with a firing pin and, optionally, a retainer, lock pin, ring and safety bracket. The initiation device can be placed as a coaxial insert in the igniter casing or integrated into it in the course of the casing manufacturing process. A cavity or a step can be made on the casing internal wall giving additional support to the element and thus ensuring more secure retention of the initiation element in the casing. If the anvil is made as an insert, its diameter should marginally exceed the internal diameter of the igniter casing.
The impact-based mechanism allows for axial or radial movement within the casing driven by a spring. Hammer and firing pin can be separate elements or combined in one.
A firing pin is preferably made wedge-shaped with a sharp or blunt end, but it can also be T-shaped in longitudinal section, like a pin expanding to the top. The moving firing pin penetrates into the anvil axial channel with its sharp or blunt end, or with the vertical part of the pin, punching or scratching the channel walls, which leads to the IC ignition. The cone shape of the end-to-end channel increases the surface touching the firing pin, which increases the friction between the pin and the wall, which is necessary to fire up the compound.
A firing pin can be inserted into the axial channel in advance and located separately from the hammer. Upon firing, the hammer pushes the firing pin into the channel causing its tight movement and leading to a quick strong friction impact on the channel wall.
In the case of primer installation above the channel, e.g., supported by the collar, a firing pin can transmit the impact forming the initial ray of flame passing through the channel towards the compound or material to be ignited.
A collar on the element improves the alignment of the firing pin with the end-to-end channel.
A firing pin can contain a cavity connecting it to the outer surface, which contains a pyrotechnical, explosive or flammable compound that is being ignited when triggered.
If hammer is not included in the design, a pressure-friction initiation mechanism can be implemented. For which purpose the wedge- or pin-shaped firing pin is pre-located in the channel. The channel internal surface, the vertical part of the pin and the IC are designed to transform the friction impulse into the flame.
Mechanical parts such as primer casing, hammer, firing pin, lock pin, ring, safety bracket, anvil can be made of polymer, metal or composite materials. A spring is preferably made of metal for reliability reasons.
To induce the friction initiation mechanism, the primer can be equipped with an elongate flexible of rigid friction element, e.g., cord, stripe, wire or bar partially located in the anvil axial channel.
A bar can contain a cavity connecting it to the outer surface which contains pyrotechnical, explosive or flammable compound that is being ignited on trigger. The bar outer surface can be engraved with longitudinal grooves or cavities which can also contain pyrotechnical or explosive compound.
In case of impact-based friction, pressure friction or friction mechanism, IC can be placed onto the channel and/or the firing pin and/or the scratcher surface.
From the side of the exit hole, the anvil is sealed by coupling the igniter with the initiation change container (cartridge) and/or with the sealing membrane.
For easier installation of the igniter with the said initiation device, internal or external thread is made on the igniter casing to allow screwing on or in the casing of an explosive device. Glue can also be used to mount the igniter.
Changing the initial impulse and ignition compound allows adapting the initiation device to applications in various explosive and pyrotechnical devices, depending on the final performance required.
Sealing of a small amount of the ignition compound significantly extends the device service life compared to the known countertypes. If the initiator elements are made of polymer or other corrosion (oxidation)-resistant material, the service life of the final device is practically unlimited.
The mechanical parts—anvil, firing tip, hammer, flexible or rigid friction elements can be made of combustible materials.
Other objects of the present invention comprise a munition and a pyrotechnical device containing the said initiation device in the ignition unit. Thereby the device can be used as an insert in the ignition unit or manufactured with the casing of a munition or a pyrotechnical device thus forming together the ignition unit. No conventional primer is required if the said initiation device is used in a munition or a pyrotechnical device. As an alternative to the primer, the initiation device is able to form a stable ray of flame. But depending on the compounds and materials to be initiated, the impulse can be transformed to trigger the device.
While the invention may be susceptible to embodiment in different forms, there are described in detail herein below, specific embodiments of the present invention, with the understanding that the instant disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that as described herein.
The igniter with the initiation device is installed into the explosive or pyrotechnical device; or the initiation device is first connected to the charge container and then this assembly is placed in the device or instrument. The triggering principle is explained on the example of a hand grenade—an impact-based action weapon.
For activation, the safety bracket is tightly pressed towards the casing and the lock pin is pulled out by the ring, releasing the retainer and allowing free movement of the bracket. When the bracket is lifted up, the retainer moves out of the hole in the casing. When the constraining element is removed, the spring quickly expands transmitting the impulse to the impact-based mechanism along the casing towards the initiating element. The moving firing pin destroys (breaks) the sealing membrane and penetrates into the ignition channel of the initiation device. At the moment of the impact, the firing pin causes direct impact-based friction impact on the ignition compound and forms the flame wave which passes through the end-to-end ignition channel and fires up the charge.
If a primer is used, the firing pin hits the primer which ignites the charge with a ray of flame.
To trigger the friction-induced device, the elongate flexible or rigid element is quickly pulled by its loose end. The movement of the opposite side of the element, which is located inside the initiation device, causes a friction impact on the compound inside the channel thus causing the ignition.
The suggested device permits:
If the initiation device is used according to this invention, no strong impact is needed to create the initial (impact-based or friction-based) impulse. However, such impact is sufficient to induce strong friction at the wall surface thus forming stable combustion.
The invention ensures high functional reliability and accurate triggering, it is simple and compact. The manufacturing process of the suggested device is well automated and safe. The device reliability ensures getting the ignition impulse under any application conditions. The versatility of the element (anvil) allows using it in a variety of initiators and devices of various mechanisms of action and power. Depending on the initiation method and the used compound, the device can be effectively used to initiate combustion (e.g., of gunpowder or a pyrotechnical charge), glowing (e.g., in smoke generators), explosion (e.g., explosive or pyrotechnical devices). The invention design is not bound to a particular IC and does not depend on the charge, material or compound being initiated. Therefore, the suggested initiator can be effectively used in the ignition unit of any explosive or pyrotechnical device, which includes practice, training, imitation devices etc., and also ammunition such as mines, caseless ammunition, shells. The suggested device is simple and inexpensive in production and does not require special handling skills.
Information sources:
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014104146 | Feb 2014 | RU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/RU2015/000074 | 2/5/2015 | WO | 00 |
