Note: Descriptions are shown in the official language in which they were submitted.
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Diversionary Device
Technical Field of the Invention
The present invention relates to a multi-burst diversionary device and to
a method of igniting the fuzes of a plurality of pyrotechnic cartridges in a
multi-
burst diversionary device.
Background to the Invention
Diversionary devices, sometimes also referred to as stun grenades or
distraction devices, are generally intended for use by law enforcement and
military personnel to physiologically and psychologically stun an intended
victim or victims in high-risk situations. Known diversionary devices
generally
comprise a housing containing an energetic pyrotechnic charge and a firing
arrangement with a small time delay. When activated, the known diversionary
devices emit a loud noise, a pressure wave and a flash of light to stun the
intended victim but without expelling matter that might cause physical injury.
More recently, diversionary devices have been developed which emit multiple
bursts of noise, pressure and light rather than a single burst. It is believed
that
this is more disorientating; especially if the bursts become louder and more
intense giving the impression the device is getting closer to the victim.
It is known to use a pyrotechnic charge housed in a replaceable cartridge
in a diversionary device. The known cartridges are similar to the so called
"flash-bang" cartridges that are commercially available and used typically for
scaring birds and often comprise a cylindrical housing containing a
combustible
fuze and a pyrotechnic charge. The length and composition of the fuze
determines the time delay between ignition of the fuze and deflagration of the
pyrotechnic charge. Such cartridges are sometime referred to as "sound units".
In WO 2011086388 Al we disclosed a multi-burst diversionary device
housing a number of replaceable pyrotechnic cartridges. The device has a
firing
arrangement incorporating a percussive ignition cap containing a primer
charge.
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When the cap is fired, a proportion of the heat and pressure given off is
directed
on to the fuze of each of the cartridges so that the fuzes of all the
cartridges are
ignited at the same time. To provide a multi-burst effect, the cartridges have
fuzes with a different time delay arranged so that the pyrotechnic charges are
deflagrated sequentially. Whilst this arrangement is highly effective, there
are
drawbacks. Generally speaking, in order to obtain a longer delay it is
necessary
to increase the physical length of the fuze resulting in a corresponding
decrease
in the volume of pyrotechnic charge that can be included in a cartridge of any
given size. As a result, there is a limit on the number cartridges that can be
incorporated in a device before the length of fuze required to provide a
suitable
delay for the later bursts means that there is insufficient room for an
effective
amount of the pyrotechnic charge. A further drawback is that each of the
cartridges in the device must have a different delay to produce sequential
firing.
This requires that a range of cartridges with different fuze delays be
provided
and that each device must be loaded with a correct set of cartridges.
It is an object of the present invention to provide a multi-burst
diversionary device which overcomes or at least mitigates the drawbacks of the
known diversionary devices.
It is a further object of the invention to provide a multi-burst
diversionary device which is simpler in design and so cheaper and easier to
manufacture than known multi-burst diversionary devices.
It is also an object of the invention to provide an alternative method of
igniting the fuzes of a plurality of cartridges in a multi-burst diversionary
device.
Summary of the Invention
In accordance with a first aspect of the invention, there is provided a
diversionary device comprising a housing holding a plurality pyrotechnic
cartridges arranged in series, each cartridge having a combustible fuze and a
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pyrotechnic charge; and a firing arrangement including a primer charge; the
housing defining a first flow path configured to channel hot gases from the
primer charge onto the fuze of a first cartridge in the series only, the
housing
defining further flow paths configured to channel a portion of the hot gasses
given off on deflagration of the pyrotechnic charge in each of the cartridges
onto the fuze of an adjacent downstream cartridge.
In a device in accordance with the first aspect of the invention, only the
fuze of a cartridge in the first compartment in the series is ignited by the
primer
charge, the fuzes in subsequent cartridges are ignited sequentially utilising
a
portion of the hot gases produced when the pyrotechnic charge of a cartridge
in
the preceding compartment deflagrates. Sequentially igniting successive
cartridges in series gives rise to a multi-burst effect without the need for
the
cartridges to have fuzes with different time delays and so enables a multi-
burst
device to be constructed to hold any desired number cartridges. Indeed, all
the
cartridges may have a fuze with the same time delay and the device could be
loaded with a plurality of identical cartridges. This significantly simplifies
the
manufacture and supply of cartridges and the loading of the device. That said,
it
will be appreciated that the cartridges need not all be the same. For example,
it
may be desirable to use cartridges with different pyrotechnic compositions to
create a particular effect over the series of bursts.
The further flow paths might be configured to channel a portion of the
hot gasses given off on deflagration of the pyrotechnic charge in at least one
of
the cartridges onto the fuze of at least two adjacent downstream cartridges.
The device may hold more than one series of cartridges, the housing
defining a first flow path configured to channel hot gases from the primer
charge onto the fuze of the first cartridge in each series, the housing
defining
further flow paths configured to channel a portion of the hot gasses given off
on
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deflagration of the pyrotechnic charge in each of the cartridges in each
series
onto the fuze of an adjacent downstream cartridge in the series.
Each cartridge may be held in a compartment defined in the housing.
Each compartment may have a fuze end and a charge end, the further
flow paths being configured to fluidly connect a fuze end of each compartment
with the charge end of the preceding upstream compartment in the series.
Each compartment may comprise a chamber defined within the housing,
the further flow paths connecting the chambers sequentially in series, a fuze
end region of each chamber in the series downstream from the first chamber
being connected by means of a flow path with a charge end region of the
preceding upstream chamber in the series. The chambers may each have a
substantially cylindrical region in which at least part of a respective
cartridge is
a close sliding fit.
The housing may also define flow paths for connecting each chamber
with atmosphere. For each pair of adjacent chambers in the series, the housing
may define a flow path which interconnects the charge end region of the
upstream chamber in the pair to the fuze end region of the downstream chamber
in the pair and which also connects both end regions to atmosphere.
The primer charge may be provided in percussion cap, the first flow path
connecting the percussion cap with the fuze end of the first compartment in
the
series. The device may further comprise a firing mechanism for selectively
activating the percussion cap. The firing mechanism may comprise a firing pin
which is resiliently biased to a firing position in which it contacts the cap
to
activate the primer charge, the pin being movable from the firing position to
a
non-firing position in which it is spaced from the primer charge against the
bias
force. The firing mechanism may also comprise a release lever, the lever being
movable between a non-release position in which it holds the firing pin in the
non-firing position and a released position in which the firing pin is able to
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move to the firing position under the bias force. The firing mechanism may
also
comprise a removable safety pin for holding the lever in the non-release
position. The firing pin may be provided on a striker plate.
At least some of the compartments in the series may be arranged in an
5 array, longitudinally overlapping one another. The compartments could be
disposed about a central axis generally parallel to one another. The housing
may comprise a main body portion having a central axis with at least some of
the compartments disposed in the main body portion about the axis. The main
body portion may be generally cylindrical. The compartments may be arranged
so that the charge end of each compartment is located adjacent the fuze end of
the next downstream chamber in the series. The housing may comprise a first
end cap and a second end cap, the end caps being releasably mountable to
opposite ends of the main body portion, the end caps defining the further flow
paths interconnecting compartments sequentially in series. The first end cap
may also comprise a mounting for receiving a firing mechanism and define at
least part of the first flow path for fluidly connecting the primer charge
with a
fuze end of a first one of the compartments in the series. The compartments
may be arranged in two or more rows about a central axis.
The compartments could be disposed generally in a common plane. The
housing may comprise a main body in which the compartments are located and
a firing mechanism releasably mountable to the main body. The compartments
may be chambers defined in the main body. The main body may be provided in
two parts releasably attachable to one another, the chambers and fluid flow
paths being defined by corresponding formations in mating faces of the two
parts. The compartments may be arranged in two or more rows in the common
plane.
The compartments in the series may be arranged axially in-line. In this
case, the housing may be elongate having an upstream end and a downstream
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end, the firing arrangement being located at the upstream end. The housing may
comprise a plurality of housing sections releasably mountable to one another.
The housing may comprise at least two tubular housing members including a
first tubular housing member having an end cap at an upstream end
incorporating, or to which is mounted, the firing mechanism and a final
tubular
housing member having a second end cap at a downstream end; each pair of
adjacent tubular housing members being releasably interconnected by an
adaptor. The first end closure and each of the adaptors may define at a
downstream end a recess which opens into the interior of the adjacent
downstream tubular housing member, the recess being dimensioned to receive
and hold a fuze end of respective one of the pyrotechnic cartridges. Each of
the
adaptors may also define a further recess at an upstream end which opens into
the interior of the adjacent upstream tubular housing member for receiving a
charge end of a respective one of the pyrotechnical cartridges, the adaptor
also
defining a flow path fluidly connecting the recess at the downstream end with
the further recess at the upstream end. The adaptor flow path may comprise at
least one flow passage which is offset from the axial centreline of the
recess.
The tubular housing members may each have one or more vent openings
therethrough.
In accordance with a second aspect of the invention, there is provided a
multi-burst diversionary device comprising: a housing holding a plurality
pyrotechnic cartridges and a firing arrangement operatively connected with a
first one of the cartridges to ignite said first one of the cartridges only,
the
device comprising formations for directing on to each of the remaining
cartridges a portion of the hot gas given off on deflagration another of the
cartridges.
In accordance with a third aspect of the invention, there is provided a
method of operating a multi-burst diversionary device comprising a plurality
of
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pyrotechnic cartridges each cartridge having a combustible fuze and a
pyrotechnic charge, the method comprising:
a. using
a primer charge to ignite the fuze of a first one of the
cartridges;
b. sequentially
igniting the fuzes of the remaining pyrotechnic
cartridges in series by directing a portion of the hot gasses given off by an
upstream cartridge in the series when it deflagrates onto the fuze of the next
adjacent downstream cartridge.
Detailed Description of the Invention
Several embodiments of a diversionary device in accordance with the
present invention will now be described, by way of non-limiting example only,
with reference to the accompanying drawings, in which:
Figure 1 is a perspective view of a first part of the main body of a
diversionary device in accordance with a first embodiment of the invention;
Figure 2 is similar to Figure 1 but includes arrows indicating the
direction flow of fluid along the various fluid passageways;
Figure 3 is a longitudinal cross sectional view on an enlarged scale
through a typical pyrotechnic cartridge for use in a diversionary device in
accordance with the invention;
Figure 4 is a side view of a main body member forming part of a housing
of a diversionary device in accordance with a second embodiment of the
invention;
Figure 5 is an end view of the main body member of Figure 4;
Figure 6 is a cross sectional view taken on line A-A of Figure 7 of a first
end cap forming part of the housing of the diversionary device in accordance
with the second embodiment of the invention for use with the main body
member of Figures 4 and 5;
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Figure 7 is an end view of the first end cap of Figure 6;
Figure 8 is a side view showing hidden detail of second end cap foiming
part of the housing of the diversionary device in accordance with the second
embodiment of the invention for use with the main body member of Figures 4
and 5 and the first end cap of Figures 6 and 7;
Figure 9 is an end view of the second end cap of Figure 8;
Figure 10 is a schematic side view of the diversionary device in
accordance with the second embodiment;
Figure 11 is a longitudinal cross-sectional view through a diversionary
device in accordance with a third embodiment of the invention;
Figure 12 is a side view of an adaptor forming part of the device of
Figure 11;
Figure 13 is an end view of the adaptor of Figure 12;
Figure 14 is a side view of a diversionary similar to that shown in Figure
11 but expanded to include three pyrotechnic cartridges, with certain parts
shown ghosted to enable internal details to be seen;
Figure 15 is schematic representation of an alternative configuration of
pyrotechnic cartridges which could be adopted in diversionary device similar
to
that of the first embodiment of the invention as illustrated in Figures 1 and
2;
and,
Figure 16 is a view similar to that of Figure 10 illustrating an alternative
arrangement of pyrotechnic cartridges in a diversionary device similar to that
of
the second embodiment of the invention as illustrated in Figures 4 to 10.
With reference to Figures 1 to 3, a diversionary device in accordance
with a first embodiment of the present invention is indicated generally at 10.
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The device 10 has a housing with a main body to which is mounted a
firing mechanism, indicated schematically at 14. The main body is formed in
two parts, only one of which 12 is illustrated, the other part being
substantially
a mirror image of the part 12 shown. The part 12 is a generally rectangular
block of material having a mating face 16. The part 12 can be made of any
suitable material such as a metallic material including steel or
aluminium/aluminium alloy. Formed within the material are recesses 18 which
one open on to the mating face 16. The second part has a corresponding mating
face and corresponding recesses. The two parts 12 are connected together
mating face to mating face to form the main body and held together by a
number of releasable fastenings, such as screws (not shown). When connected
together, the opposed recesses 18 in the mating faces 16 of the two parts
define
a number of cylindrical chambers 20a ¨ 20h arranged in a common plane, and a
number of fluid passageways which interconnect the chambers fluidly in series
and connect each of the chambers with atmosphere at the exterior of the main
body 12. The recesses also define a first fluid passageway which fluidly
connects only a first of the chambers with the firing arrangement.
In the present embodiment, there are eight chambers in the main body
but the number of chambers can be varied as desired. Each of the chambers 20
has a cylindrical region configured to receive a cylindrical pyrotechnic
cartridge
22, an example of which is shown in Figure 3 on an enlarged scale.
Each cartridge 22 has a cylindrical housing 24 closed at one end by an
end closure 26. The housing contains a pyrotechnic charge 28 located towards
the closed end of the housing and an ignitable and combustible fuze 30 at the
open end. Each chamber 20 has a fuze end 20' and a charge end 20", the
cartridges 22 being inserted in the chambers with the open fuze at the fuze
end
20' of each chamber as illustrated schematically in chambers 20a to 20c in
Figure 1 with the cross hatching representing the fuze 30. At the charge end,
the chambers have an extended region 32 of reduced diameter in comparison
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with the cylindrical region into which the end closure 26 of the cartridge is
blown when the pyrotechnic charge is ignited and deflagrates.
The cartridges 22 may be similar to so called "flash-bang" cartridges that
are commercially available and used typically for scaring birds. The
cylindrical
5 housing
24 may be made of paper or cardboard or the like but any suitable
material can be used. The pyrotechnic charge 28 may be any suitable
composition which produces the required combination of sound, light and
pressure. A differently composed pyrotechnic charge 28 may be used in
some/all of the cartridges 22 in the device 10 to create different effects.
For
10 example,
the cartridges 26 may have different pyrotechnic charge compositions
so that when ignited sequentially, each successive cartridge produces a louder
noise, more light and more pressure. This gives the impression that the device
10 is moving closer to the victim even though the device is substantially
stationary.
Whilst it is expected that the device in accordance with the invention
will use pyrotechnic cartridges with a combustible fuze 30 to provide a delay
between each successive deflagration ("flash-bang"), at least some pyrotechnic
cartridges with no fuze could be used, though this would result in a series of
closely spaced bangs.
Seven of the chambers 20b ¨ 20h are arranged parallel to one another in
a closely spaced array whilst the first chamber 20a is inclined at an angle to
the
others and is more widely spaced at its fuze end 20'. This positions the fuze
end
20' of the first chamber 20a so as to be more easily connected with the firing
arrangement 14 by a first fluid passageway 40.
The firing arrangement is releasably mountable to the main body 12 and
houses a percussive ignition cap containing a primer charge which emits a
flash
of heat and pressure (hot gasses) when the cap is struck with a sufficient
force.
The firing arrangement also includes a firing mechanism to fire the ignition
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cap. This can be any suitable arrangement such as a conventional sprung loaded
striker plate and release leaver assembly of the type described in WO
2011086388 Al. However, any suitable firing mechanism could be used such
as an inertia activated toggle of the type disclosed in EP 1705454 B.
For convenience, the term "flash" will be used in this description to refer
collectively to the heat, pressure wave, light, sound and material given off
by
the primer charge in the percussion cap when it is set off and/or by a
pyrotechnic charge in one of the cartridges 22 when it deflagrates. It will be
understood, however, that it is the hot gas or gases given off or produced by
the
pyrotechnic charges which is of primary importance for use in igniting a fuze
30 of a subsequent cartridge 22.
The firing arrangement includes a fluid passageway which connects with
the first fluid passageway 40 in the main body to form a flow path along which
at least a portion of the hot gasses given off by the primer charge is able to
flow
into the fuze end 20' of the first chamber 20a. Fluid passageways 42, 44
defined in the main body connect the fuze end and the charge end respectively
of the first chamber 20a to atmosphere at the exterior of the main body. A
further flow passageway 46 fluidly connects the charge end of the first
chamber
20a to the fuze end of the second chamber 20b.
The chambers are all positioned top to toe so that the fuze end of one
chamber is located next to the charge end of the adjacent chamber or chambers.
Adjacent pairs of the second to eighth chambers 20b to 20h are each
interconnected by a generally "Y" shaped fluid passageway 48. The "Y" shaped
passageway 48 interconnecting the second chamber 20b and the third chamber
20c will be described in detail. This "Y" shaped passageway 48 includes a
first
fluid passageway portion 48a extending coaxially from the fuze end of the
downstream chamber 20c to an outlet 50 at the edge of the main body 12 where
it opens into the atmosphere. A second passageway portion 48b extends from
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the extended region 32 at the charge end of the upstream chamber 20b to the
first passageway portion 48a approximately midway between the outlet 50 and
the chamber 20c. The second passageway portion 48b extends from a position
approximately midway along the extended region 32 so that it is not blocked by
the cartridge end closure 26 which is blown into the end of the extend region
when the cartridge is fired. The second passageway is angled relative to the
axis
of the upstream chamber 20b so that fluid flowing thought it is directed into
the
first passageway portion 48a primarily in an outward direction towards the
outlet end 50 such that when the pyrotechnic charge in chamber 20b
deflagrates, most of the flash given off will pass out of the main body
through
first passageway portion outlet 50 as indicated by arrow 52 in Figure 2.
However, some of the flash, including hot gases, will flow along the first
passageway portion 48a into the fuze end of the downstream chamber 20c, as
indicated by arrow 54. The remaining pairs of chambers 20c and 20d, 20d and
20e, 20e and 20f, 20f and 20g, 20g and 20h are each interconnected by a
similar
"Y" shaped passageway 48 and the charge end of the final chamber 20h is
connected to atmosphere by a passageway 56 which extends from the extended
region 32 to an outlet 58 at the edge of the main body.
In use, the device 10 is loaded with a cartridge 22 in each of the
chambers 20, the main body is assembled and the firing arrangement with the
primer charge mounted to the main body. When the firing arrangement is
activated, the primer charge gives off a flash of pressure and heat and
material
including hot gasses which passes through the first fluid flow passageway 40
onto into the fuze end of the first chamber 20a, as indicated by arrow 60 and
ignites the fuze 30 of the cartridge in the first chamber 20a. After a short
delay
determined by the fuze 30 of the first cartridge, the main pyrotechnic charge
28b is ignited and deflagrates giving off a larger flash of light, heat,
pressure
wave and sound. The majority of the flash passes through the fluid passageways
42, 44 to atmosphere as indicated by arrows 62 and 64 to produce a burst of
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sound, light and pressure. However, as indicated by arrow 66, a portion of the
flash, including hot gas, passes along the fluid flow passageway 46 to enter
the
fuze end of the second chamber 20b where it ignites the fuze 30 of the
cartridge
in the second chamber.
After a further short delay, determined by the fuze 30 in the second
cartridge, the main pyrotechnic charge 28 in the second cartridge deflagrates.
The bulk of the flash given off by the second cartridge passes out of the
device
through the first and second fluid passage way portions 48a, 48b and outlet 50
of the "Y" shaped passageway 48 interconnecting the second and third
chambers 20b, 20c as indicated by arrows 52, though some will pass out of the
main body through the fluid passageway 46, the extended region 32 of first
chamber 20a and fluid flow passageway 44. A proportion of the flash of heat
and pressure including hot gasses given off by the pyrotechnic charge of the
cartridge in the second chamber 10b though passes along the first passage
portion 48a into the fuze end of the third chamber 20c, as indicated by arrow
54, where it ignites the fuze 30 of the cartridge in the third chamber. The
process continues in a chain-like reaction, with all the remaining cartridges
22
in the device being sequentially ignited from the flash given off by the
previous, upstream cartridge in the series.
Connecting the cartridges together sequentially in series in the manner of
a daisy chain enables the cartridges to be fired sequentially without the need
to
use different length fuzes. This means that virtually any number of cartridges
could be included in the device without unduly limiting the amount of
pyrotechnic charge that can be incorporated in those cartridges that are fired
later in the sequence and allows the device to be loaded with a plurality of
identical cartridges if desired.
Figure 15 illustrates schematically an alternative configuration of
cartridges 22 in a planar array that could be adopted in a device 10 as
described
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above. In this configuration, the cartridges are arranged in two rows and the
arrows 68 indicate the flow of hot gases from one cartridge to next in the
series
in order that, with the exception of the first cartridge which is ignited from
a
primer charge, each of the remaining cartridges are ignited in turn by the hot
gasses given off when the previous cartridge. It will be appreciated than many
other configurations could be adopted by suitable design of the cartridge
chambers and interconnecting flow paths.
It will be appreciated that the concept of sequentially igniting subsequent
cartridges in a multi-burst diversionary device is not limited to devices
where
the chambers are arranged in a common plane but can be adapted for use in
devices with a range of different designs, provided that fluid flow paths for
directing or channelling a proportion of the flash, and in particular the hot
gas,
given off or generated by each cartridge as it deflagrates onto the fuze an
adjacent cartridge downstream in the series are defined. For example, the
chambers could be aligned co-axially in-line with one another or they could be
arranged about a common axis in a cylindrical housing as described in the
following embodiments.
Figures 4 to 10 illustrate a further embodiment of a diversionary device
10' in accordance with the invention in which the housing is generally
cylindrical and the compartments 20 are arranged in a circular array about a
central longitudinal axis.
The housing 12 of the device 10' comprises three main parts, a main
cylindrical body member 12a, a first end cap 12b and a second end cap 12c.
Extending through the main body 12a is a small diameter central through bore
70 aligned with a central longitudinal axis of the main body. Disposed in an
about the central through bore and longitudinal axis is an array of 6 larger
diameter through bores 20a to 20f which define compartments or chambers for
receiving pyrotechnic cartridges 22, such as those shown in Figure 3. The
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compartments 20 are not equi-spaced about the central axis but arranged into
adjacent pairs.
The end caps 12b and 12c are releasably mounted to opposite ends of the
main body to hold the cartridges 22 in their respective compartments and serve
5 to define flow paths that connect the compartments in series for
sequential,
serial ignition of the cartridges.
A first end cap 12a comprises a cylindrical disc portion having an outer
diameter which is substantially the same as that of the main body 12a and
which has a planar end face 72 which abuts an end face 74 of the main body
10 when the housing is assembled. A spigot 76 projects axially out from the
other
end face 78 of the disc. The spigot 76 has an external thread 80 on to which
can
be mounted a firing pin arrangement. A central bore 82 extends through the
first end cap. An inner end region 82a of the bore has an internal thread
whilst
an outer end region is 82b is recessed to hold a percussive ignition cap 83
15 containing a primer charge.
The second end cap 12c is also in the form a cylindrical disc having an
outer diameter which is substantially the same as that of the main body 12a
and
which has a planar end face 84 which abuts the other end face 86 of the main
body when the housing is assembled. A central bore 88 extends through the
centre of the disc, the bore having a wider diameter recessed region 88a at
its
outer end. When the housing 12 is assembled, the end caps 12b, 12c are
clamped firmly to the ends of the main body 12a by means of an elongate screw
(not shown) which is inserted though the central bore 88 in the second end cap
and the central bore 70 in the main body to engage with the internal thread
82a
in the central bore of the first end cap. The elongate screw having a head
which
is received in the recess 88a of the central bore 88 in the second end cap.
The cartridges 22 in the compartments 20a-20f are arranged head to toe,
with the fuzes 30 of the cartridges in the first, third, and fifth compartment
20a,
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20e, 20e being located adjacent the first end cap 12b and the fuzes 30 of the
cartridges in the second, fourth and sixth compartments 20b, 20d, 20f being
located adjacent the second end cap.
A bore 90 extends through the disc portion of the first end cap 12b in
registration with the fuze end of the first compartment 20a. A radially
extending recess 92 is provided in the inner face of the disc which merges
with
the bore 90 and extends radially inwardly. An angled bore 94 connects the
interior of the recess with an outer end region of the central through bore
82.
The central through bore 82, the angled bore 94 and the recess 92 together
define a first flow path along which the hot gasses given off by the primer
charge in the ignition cap 83 in the outer recessed end of the bore 82 can
flow
to enter the fuze end of the first compartment 20a. The bore 90 forms an
exhaust vent through which a portion of the flash given off when the
pyrotechnic charge of the cartridge in the first compartment deflagrates can
escape to atmosphere.
Two arcuate recesses 96, 98 are formed in the inner face 72 of the first
end cap 12a, each recess being connected to atmosphere by an exhaust vent
hole 100 extending through the remainder of the end cap to the outer end face
78 of the disc portion. A first of the recesses 96 partially overlaps the ends
the
second and third compartments 20b, 20c in the main body to define a flow path
fluidly interconnecting the charge end of the second compartment 20b with the
fuze end of the third compartment 20c. The recess 96 and the vent hole 100
also
fluidly connect the two chambers with atmosphere. The second of the recesses
98 partially overlaps the ends the fourth and fifth compartments 20d, 20e in
the
main body to define a flow path fluidly interconnecting the charge end of the
fourth compartment 20d with the fuze end of the fifth compartment 20d. The
recess 98 and the vent hole 100 also connect the two chambers 20d, 20e with
atmosphere. A further exhaust vent hole 102 is formed through the disc portion
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of the first end cap in line with the sixth compartment 20f to connect the
compartment with atmosphere.
Three circular recesses 104, 106, 108 are formed in the inner mating
surface 84 of the second end cap 12c equi-spaced about its centre. A smaller
diameter exhaust vent hole 110 is formed through the remainder of the disc
portion at the base of each of the recesses to connect each recess with
atmosphere. The recesses 104, 106, 108 are positioned so that each one aligns
with a respective pair of the compartments 20a-20f. The circular recesses 104,
106, 108 are dimensioned so that they only partially overlap the ends of the
adjacent compartments so as to fluidly connect them whilst the second end cap
12c holds the cartridges in the compartments. The exhaust vent holes 110
fluidly connected the two respective compartments to atmosphere. In this
embodiment, a first circular recess 104 aligns with the ends of the first and
second compartments 20a, 20b in the main body so as to fluidly connect the
charge end of the first compartment 20a with the fuze end of the second
compartment 20b, the vent hole 110 fluidly connecting the compartments 20a,
20b with atmosphere. A second circular of the recesses 106 aligns with the
ends
of the third and fourth compartments 20c, 20d in the main body so as to
fluidly
connect the charge end of the third compartment 20c with the fuze end of the
fourth compartment 20d, the vent hole 110 fluidly connecting the compartments
20c, 20d with atmosphere. A third of the circular recesses 108 aligns with the
ends of the fifth and sixth compartments 20e, 20f in the main body so as to
fluidly connect the charge end of the fifth compartment 20e with the fuze end
of the sixth compartment 20f, the vent hole 110 fluidly connecting both
compartments 20e, 20f with atmosphere.
In the assembled device 10', the recesses and vent holes in the end caps
12b, 12c form flow paths which connect all the compartments 20a-20f
sequentially in series. In other words, they form a chain of flow paths which
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allow each cartridge downstream from the first to be ignited by the hot gasses
from the preceding cartridge in the series when it deflagrates.
The fuze end of the first chamber 20a is fluidly connected with the
primer charge in the firing arrangement via the recess 92, the angled bore 94
and the axial bore 82 in the first end cap which collectively form a first
fluid
passageway. The charge end of the first compartment 20a is connected with the
fuze end of the second compartment 20b by the first circular recess 104 in the
second end cap. The charge end of the second compartment 20b is connected
with the fuze end of the third compartment 20c by the first arcuate recess 96
in
the first end cap. The charge end of the third compartment 20c is connected
with the fuze end of the fourth compartment 20d by the second circular recess
106 in the second end cap. The charge end of the fourth compartment 20d is
connected with the fuze end of the fifth compartment 20e by the second arcuate
recess 98 in the first end cap. Finally, the charge end of the fifth
compartment
20e is connected with the fuze end of the sixth compartment 20f by the third
circular recess 108 in the second end cap.
In use, a pyrotechnic cartridge 22 is loaded into each of the
compartments 20a-20f in the main body 12a in the appropriate orientation. The
end caps 12b, 12c are mounted to the ends of the main body and secured in
position. A percussion cap 83 including a primer charge is loaded into the
recessed end 82b of the axial bore in the first end cap 12b and a firing
mechanism 85 is mounted to the first end cap 12b. The firing mechanism 85 is
a conventional firing mechanism of the type disclosed in WO 2011086388 Al
and comprises a release lever 85a for controlling the release of a spring
loaded
striker plate which when released is urged to strike the percussion cap in
order
to set off the primer charge and a removable safety pin 85b. However, other
types of firing mechanism can be adopted.
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When the device 10 is activated and the primer charge set off, the flash
of heat, pressure and material given off by the primer charge passes through
the
first fluid passageway comprising the axial bore 82, the angled bore 94, and
the
recess 92 in the first end cap and enters the fuze end of the first
compartment
20a to ignite the fuze 30 of the cartridge in the first compartment. After a
short
delay, the pyrotechnic charge 28 in the first cartridge is ignited and
deflagrates
giving off a large flash of light, heat, pressure wave, and sound. The
majority of
this flash passes out through the vent hole 90 and the vent hole 110 in the
first
circular recess 104. However, a portion of the flash including hot gas is
guided
by the first circular recess to enter the fuze end of the second compartment
20b
where it ignites the fuze of the second cartridge in the second compartment
20b.
When the second cartridge deflagrates, the majority of the flash given off
passes out though the vent hole 110 in the first circular recess 104 and the
vent
hole 100 in the first arcuate recess 96 in the first end cap 12b. A portion of
the
hot gasses though is guided by the first arcuate recess 96 to enter the fuze
end
of the third compartment 20c to ignite the fuze of the third cartridge in the
third
compartment. This process continues with each cartridge being ignited by a
portion of the hot gasses (flash) given off by the cartridge in the previous
upstream compartment by means of the flow paths as described above.
Figure 10 is a somewhat schematic side view of the assembled device
10' which is ghosted to show the positions of the cartridges 22 in main body
member 12a, though details of the compartments 20a-20f themselves are
omitted for clarity. Arrows 54 indicate the flow of hot gas from one cartridge
when it deflagrates onto the fuze of the next adjacent downstream cartridge to
ignite the fuze of the downstream cartridge. The arrows 52 indicate the
movement of flash to atmosphere through the exhaust vent holes when each
cartridge deflagrates.
It will be appreciated various changes can be made to the device 10'
without departing from the inventive concept. For example the number of
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compartments in the main body 12a can be changed with an appropriate change
to design of the end caps 12b, 12c to ensure that the compartments are
connected in series. Other changes can also be made. For example, elongate
actuate holes could be provided through the disc part of the first end cap 12b
5 rather than the recesses 96, 98 and vent holes 100. Similarly, the
circular
recesses 104, 106, 108 in the second end cap 12c could be replaced by simple
through holes. These changes would allow the compartments to vent more
easily ensuring that a sufficiently large flash is emitted whilst the shroud
effect
of the end cap surrounding the holes constrains sufficient heat and pressure
(hot
10 gas) given off by one cartridge when it deflagrates to pass though to
the fuze
end of the next compartment. The disc portion may need to be of sufficient
thickness to ensure that it channels sufficient of the hot gasses onto the
fuze of
the downstream cartridge but this can be established for each application
relatively easily by means of trial and error if necessary. With the benefit
of the
15 teaching in this patent specification, those skilled in the art will
have no
difficulty in configuring the housing so as to deflect part of the hot gasses
given
off by each cartridge onto the fuze of an adjacent downstream cartridge.
Figure 16 illustrates a modified version of the device 10'a in which the
cartridges are arranged in two rows 112, 114 stacked one above the other (as
20 shown) in modified main body portion 12a' and separated by a divider
115. The
main body portion defines flow paths 116, 118 which direct hot gases between
pyrotechnic cartridges 22 vertically adjacent one another in the two rows so
that
all the cartridges can be ignited sequentially in series. The flow paths are
arranged so that a first cartridge 22a in the row 112 adjacent the first end
cap
12b is ignited from the primer charge. A proportion of the flash given off
when
the first cartridge 22a deflagrates is directed by means of flow passage 116
on
to the fuze of a second cartridge 22b immediately below the first cartridge in
the row 114 adjacent the second end cap 12b. Flash from the second cartridge
22b is directed by a suitable flow path defined in the second end cap 12c on
to
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21
the fuze of a third cartridge in the same row 114, whilst flow passage 118
directs a proportion of the flash from the third cartridge 22c on to the fuze
of a
fourth cartridge 22d in the first row 112 immediately above the third
cartridge.
Similar arrangements interconnect all the remaining pyrotechnic cartridges 22
in the device. It will be appreciated that various different configurations of
cartridges can be adopted by suitable design of the chambers and
interconnecting flow paths.
Figures 11 to 14 illustrate a still further embodiment of a diversionary
device 10" in accordance with the invention. In the device 10" according to
this embodiment, the compartments and cartridges are aligned axially in-line
with one another. In the embodiment as shown in Figure 12, there are two
compartments 20a, 20b each housing a corresponding cartridge 22a, 22b.
However, the device is modular in nature and any number of additional
compartments/cartridges can be added and Figure 14 illustrates the device 10"
having three compartments 20a, 20b, 20c.
The device 10" comprises a housing 12 including a first end cap 12b at
an upstream end of the device and a second end cap 12c at a downstream end.
At least two tubular housing members 12d, 12e, 12f are arranged between the
first and second end caps with adjacent tubular housing members being
interconnected by an adaptor 12g. The components of the housing can be made
of any suitable materials such as metallic materials including steel or
aluminium/aluminium alloy.
The tubular housing members 12d, 12e, 12f are identical and
interchangeable. They each have an internal thread at either end for
connection
with an end cap 12b, 12c or adaptor 12g and a number of exhaust vent holes
120.
The first end cap 12b is located at the upstream end of the device 10". It
includes a main body section 122 with a first threaded spigot 124 which
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projects from the inner end of the main body section for engagement with the
thread at one end of a first tubular housing member 12d to secure them
together. A second threaded spigot 126 projects from the outer end of the main
body section 122. The second spigot 126 is smaller in diameter than the first
and has an external thread on to which can be mounted a firing mechanism 85
similar to that of the previous embodiment, as is shown in Figure 14. A
circular
recess 128 is formed coaxially in the inner end of the first threaded spigot.
The
recess 128 is dimensioned to receive and hold the fuze end of a pyrotechnic
cartridge 22a. The recess may have tapered side walls for ease of inserting
the
cartridge. An axial bore 82 extends through the second spigot 126 and opens
into the recess 128. The bore has a stepped larger diameter portion 82a at its
outer end in which a percussion cap 83 containing a primer charge can be
mounted. The firing mechanism 85 includes a striker plate and/or a firing pin
which is urged to strike the percussion cap 83 when the device 10" is
activated
so as to produce a flash of heat and pressure (hot gasses) and material which
travels down the axial bore 82 to ignite the fuze of the first cartridge 22a.
The
axial bore 82 in this embodiment comprises a first flow path whilst the
downstream recess 128 in the first end cap 12b and the corresponding tubular
housing member 12d together define the first compartment 20a for receiving
the first pyrotechnic cartridge 22a.
Each adaptor 12g has a main body portion 132 with a threaded spigot
134 projecting from either end. The spigots 134 are similar to the first
spigot
124 on the first end cap 12b and are configured to engage with the threads at
the ends of two adjacent tubular housing members 12d & 12e or 12e & 12f to
join them together. A circular and tapered recess 136 is formed at the
downstream end of each adaptor for holding the fuze end of a cartridge 22b,
22c in a manner similar to the recess 128 in the first end cap 12b. A further
circular recess 138 is formed in the upstream end of each adaptor to hold the
charge end of the upstream cartridge 22a, 22b. The two recesses are fluidly
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connected by means of four bores 140 equi-spaced about a longitudinal axis of
the device. The downstream recess 136 in the adaptor and the adjacent
downstream tubular housing member 12e, 12fd together define a compartment
20b, 20c for receiving the respective pyrotechnic cartridge 22b, 22c,
The downstream end of the last tubular housing member, 12e, 12f is
closed by the second end cap 12c. The second end cap 12c comprises a main
body section 142 with a threaded spigot 144 projecting from the upstream end
of the main body section for engagement with the thread at the end of the last
tubular housing member 12e, 12f. A circular recess 145 is formed in the
upstream end of the second end cap to hold the charge end of the upstream
cartridge 22b, 22c.
When the device is activated, a flash of heat and pressure and material
produced when the primer charge in the percussion cap 83 is set off travels
down the axial bore 82 in the first end cap 12b and ignites the fuze of the
first
cartridge 22a. After a delay determined by the fuze, the first cartridge
deflagrates giving off a larger flash of heat, pressure wave, sound and light.
The
bulk of this flash passes out through the vent holes 120 in the first tubular
housing member but a portion of the hot gas in particular passes through the
recess 138 in the upstream end of the adaptor and the four bores 140 to ignite
the fuze of the second cartridge 22b. After a further delay, the pyrotechnic
charge in the second cartridge deflagrates giving of a flash of heat,
pressure,
sound and light, most of which passes out through the vent holes 120 in the
second tubular housing member 12e. Where the device 10" has more than two
cartridges, the process continues with each cartridge in the chain being
ignited
by the deflagration of the charge in the preceding upstream cartridge. In
Figure
14, the arrows 52 schematically illustrate the flow paths of the flash passing
out
through the vent holes from each cartridge as it deflagrates and the arrows 54
indicate the flow path for hot gasses from one chamber to the next to cause
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sequential firing of the cartridges. It will be appreciated that the carriages
are
set off sequentially and not simultaneously.
It has been found that it is advantageous to offset the flow path through
the adaptor 12g from the central axis of the cartridges hence the use of the
offset bores 140. However, it will be appreciated that the design of the flow
path could be varied in a number of ways and is not limited the arrangements
shown.
The main body portions 122, 132, 142 of the end caps and the adaptor
have a hexagonal outer profile so that the device 10" will tend to come to a
rest
more quickly on a surface when thrown as compared with a device which is
wholly cylindrical. Nevertheless, this feature is not essential to the main
inventive concept.
If more "bangs" are required, the device 10" can be extended by using
an additional adaptor 12g and tubular housing member 12d, 12e, 2f for each
additional cartridge. In each device 10" the first end cap 12b is mounted at
the
upstream end of the first tubular housing member and the second end cap 12c
mounted to the downstream end of the last tubular housing member, with each
adjacent pair of tubular housing members being interconnected by an adaptor
12g.
The above embodiments are described by way of example only. Many
variations are possible without departing from the scope of the invention as
defined in the appended claims. For example, generally it is expected that a
diversionary device in accordance with the invention, all the pyrotechnic
cartridges will be interconnected in a single series so as to be ignited
sequentially. However, the cartridges could be arranged in more than one
series, with a first cartridge in each series being ignited from a primer
charge
and the remaining cartridges in each series being ignited by the hot gas given
off when the previous cartridge in the series deflagrates. In a further
alterative,
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the cartridges may be arranged in a series which splits into two or more
paths.
For example, two cartridges might both be ignited from the hot gas given off
by
a single previous cartridge in a series. This arrangement could be used to
produce a loud bang at the end of a series by setting off two cartridges at
the
5 same time.
