Weatherproof safety fuse igniter

A disposable weather-proof safety fuse igniter is provided which includes a hollow cylindrical housing having an internally spaced sleeve provided for mounting and positioning a pull-wire type friction igniter cup. The end of the pull-wire is attached to a vent plug positioned at one end of the housing which, in turn, is attached to a finger-grip device for extracting the vent plug and pull-wire for ignition. A threaded cap is provided to cover and seal the vent plug end of the housing. The opposite end of the housing includes a compression type sealing retainer which has an internal bore for insertion of the safety fuse. A double O-ring seal can be positioned within the housing with the retainer arranged so that rotation of the cap causes the O-ring seal to be compressed against the inserted fuse. Internally arranged ferrules are provided within the internal sleeve for properly positioning the end of the inserted fuse, retaining the fuse in proper position for use, and channeling the flame from the primer upon ignition to light the end of the safety fuse. A metering aperture in the sleeve and a passageway through the housing allows the exhaust gases to be accurately vented. A shipping plug is provided for insertion into the end of the sealing retainer to render the device weather-proof during shipping and storage.

FIELD OF THE INVENTION 
This invention is directed to a manual type weather-proof igniter for 
igniting safety fuse. It is more specifically directed to a disposable 
improved weather-proof safety fuse igniter incorporating ignition control 
features. 
BACKGROUND OF THE INVENTION 
Safety fuses have been used for many years for the ignition and detonation 
of various types of explosives. At the present time, there are two types 
of safety fuse which are presently in use. The safety fuse which is used 
by the military and government is a composite of black powder which has an 
external layer or wrap of textile material. An outer sheath or layer of 
relatively smooth plastic is provided to maintain and provide a 
water-proof condition so that the fuse can be used in all types of 
environment. 
The type of safety fuse which is primarily used for commercial use is 
slightly different from the military type in that a layer or coating of 
asphalt is applied to the outside surface of the textile wrap provided on 
the fuse. This asphalt layer is used as a sealant between the fuse and the 
blasting cap or ignition device. In this way, the entire assembly is 
sealed to prevent water from entering the connection with the ignitor or 
blasting cap which, in turn, would render the fuse, ignitor or blasting 
cap unreliable or inoperative. 
The military type safety fuse, because it has a relatively smooth outer 
plastic layer, does not inherently provide this sealing effect. As a 
result, it is necessary to provide a separate sealing arrangement to 
prevent the introduction of water in the connection between either the 
igniter or the blasting cap. 
The prior art device which is used by the military and other government 
agencies to ignite military type safety fuse is the M-60 igniter which was 
intended to be a reusable igniter. After being used to ignite a fuse, the 
igniter is removed from the burnt fuse, disassembled and a new primer 
charge is inserted, thus, the unit is reloaded and is again ready to be 
used. 
It is a common known fact, however, that most M-60 igniters are not reused. 
The operation requiring the ignition or lighting of a fuse leading to an 
explosive charge is a nervous and dangerous time for all participants. As 
a result, it is very unlikely (not to mention unsafe) that a serviceman or 
other user will take the necessary time to remove the M-60 igniter from 
the fuse either before or after the charge has exploded. Hence, in most 
cases the M-60 igniter is discarded and not reused. This is especially 
true because the serviceman, in most cases, has an endless supply of 
igniters which minimizes the necessity to reload the igniter. In addition, 
the cost to retrieve, reload the M-60 and stock spare primers must come 
close to or exceed the cost of the M-60. 
As a result of the fact that the M-60 igniter is relatively expensive, it 
has been shown that there is a definite need for a disposable type fuse 
igniter which is not only inexpensive to produce so that it can be 
discarded, but also must be extremely reliable and meet all military, 
government and commercial specifications. As a result, the present 
invention is directed to an inexpensive, water-proof fuse igniter which is 
a one-use throw-a-way disposable igniter. 
INFORMATION DISCLOSURE STATEMENT 
The following information is provided in compliance with the inventor's 
duty to disclose all pertinent information which is relevant to the 
information which is the subject of this application. 
Although there are a number of issued patents directed to primer igniter 
devices, the patents which are listed here are believed to be the most 
pertinent which are known to the applicant. 
The Baker, et al. patent (U.S. Pat. No. 3,942,445) is directed to a 
friction igniter assembly having a pull-wire coated with a 
friction-sensitive composition which is intended to be drawn through a 
chemical igniter composition. One end of the pull-wire which is coated 
with the friction composition is deformed in a zig-zag arrangement to 
increase the friction when the wire is drawn through the igniter material. 
The opposite end of the pull-wire is securely attached so that it can be 
withdrawn with respect to the ignition composition to produce the desired 
ignition flame. 
The Beach patent (U.S. Pat. No. 82,586) discloses an enclosed, sealed 
torpedo for use in oil well servicing. This patent describes a sealed 
container which includes an explosive charge and a plurality of 
friction-primers. A pull-wire is arranged to be connected with the primers 
which are embedded in the explosive. By withdrawing the pull-wire, the 
primers are simultaneously ignited which, in turn, ignites the explosive 
charge. 
The Michaelis (U.S. Pat. No. 333,655), Sharp, et al. (U.S. Pat. No. 
549,297) Ballreich et al. (U.S. Pat. No. 3,416,450) patents all show 
friction-type igniters. All of these devices show pull-wire arrangements 
for igniting a friction charge which, in turn, ignites an explosive 
charge. It is interesting to note that although all of these devices show 
friction igniters, they are not used in conjunction with safety fuse 
products. 
German patent 299,044 discloses a pull-wire type igniter which is intended 
for igniting a precharge which provides a directed ignition flame. This 
device appears to be an enclosed or sealed unit which has an internal 
cylinder for housing the primer as well as the precharge. It also appears 
that an opening is provided in the wall of the cylinder immediately 
upstream of the precharge. 
European Pat. No. 0045226 is directed to a weatherproof or sealed igniter. 
An internal O-ring is provided for sealing one end of the primer sleeve. 
SUMMARY OF THE INVENTION 
This invention is a friction-type water-proof igniter for use with safety 
fuse. Although it is primarily intended for use with military type safety 
fuse, it can also be used with the commercial type or any other product 
wherein it is desired to ignite the end of a fuse or an explosive charge 
by the use of a primer. 
The igniter incorporates a molded or conveniently shaped housing which 
encloses a pull-wire and igniter or primer cap. At one end of the housing 
is a vent plug which is attached to the end of the pull-wire and includes 
a seal to prevent the introduction of moisture or contaminants. A Nylon 
cord or other finger-gripping device is attached to the vent plug for easy 
extraction. A closure cap is provided to cover the vent plug and further 
seal the end of the housing. 
The housing is a hollow tube which has an internal retaining sleeve which 
supports and positions the end of the pull-wire and the igniter cap. The 
internal bore of the sleeve containing the igniter cap also contains two 
positioning ferrules which have a partially crimped and jagged edge at one 
end. The ferrules are positioned internally within the sleeve with the 
ends containing the jagged edges arranged toward each other. A 
predetermined space is provided between the ferrules with the end of the 
first ferrule arranged adjacent to the outer surface of the igniter cap. 
The partially crimped end of the first ferrule is precisely located a 
predetermined distance from the face of the igniter cap to position the 
end of the safety fuse at a proper distance from the cap. The second, 
oppositely arranged ferrule is provided to allow the safety fuse to be 
inserted through this ferrule and up to the end of the first ferrule. The 
crimped and jagged edge of the second ferrule presses against the outer 
layer of the safety fuse and prevents or restricts the removal of the 
safety fuse once it has been inserted. 
One or more adequately sized vent openings are provided in the sides of the 
internal sleeve in the area between the two ferrules. The positioning and 
sizing of the metering vent hole is quite critical to the proper and 
reliable operation of the device. The vent hole must be positioned 
downstream of the end of the safety fuse and properly sized to maintain 
the desired back pressure within the housing adjacent to the fuse during 
the ignition. The hot gases and sparks from the igniter cup must be 
directed over the end of the fuse. It is known that too high a pressure in 
the ignition area can retard the ignition and burning of the fuse while a 
rapid exhaustion of the products of combustion can create a partial vacuum 
which will extract powder from the fuse which can cause failure of the 
fuse to ignite or cause unreliable burning of the fuse. 
Sufficient internal clearance is provided around the sleeve within the 
housing to direct the exhaust gases internally within the housing and 
through internal slots provided to guide the exhaust gases outward through 
the end of the housing previously containing the vent plug. 
The opposite end of the housing through which the fuse is inserted contains 
a double O-ring seal positioned in the bore provided for the fuse. A 
retaining cap or retainer is provided at this end of the housing which 
also includes a central bore for the passage of the fuse and a central 
core which contacts the double O-ring seal and causes the compression of 
the O-rings to seal against the inserted safety fuse. Slightly tapered 
surfaces around the outside edge of the retaining cap which contact ears 
located on the sleeve provide the compression forces on the O-rings when 
the retainer is rotated. For shipping and storage purposes, a solid 
insertable shipping plug is provided for insertion in the fuse end of the 
device for sealing the housing. At the time of use the retainer is rotated 
allowing the shipping plug to be removed and discarded and the safety fuse 
inserted. Once the fuse has been inserted, the retainer is rotated in the 
opposite direction to reseal the opening and to prevent the intrusion of 
water or contaminants. 
The invention is quite novel from the standpoint that the components used 
in fabricating the device can be manufactured from inexpensive materials. 
Any material can be used which is easy to machine or mold and which is not 
corrosive or reactive with the anticipated environment. In most cases, it 
is anticipated that various types of suitable plastics which can be easily 
fabricated will be used. The ferrules, because of the high temperatures 
involved and the strength requirement to retain and hold the safety fuse 
in proper position, should be fabricated from a relatively strong material 
such as steel, copper or aluminum. The finger pull-grip which is attached 
to the vent plug can be fabricated from any suitable material such as 
flexible wire or Nylon cord. It is understood that the pull wire and 
igniter cup are conventional items and are fabricated from suitable 
materials which are adequate for their intended purposes.

DETAILED DESCRIPTION OF THE DRAWINGS 
Turning now more specifically to the drawings, FIGS. 1 and 2 show a 
perspective view of the weatherproof igniter 10 according to the present 
invention as well as a partially disassembled view of the same igniter. 
The igniter 10 includes a hollow housing or body 12 having one end 14 and 
the opposite end 16. Near the end 16 of the housing 12 are located a 
number of shallow depressions 15 which are arranged substantially around 
the circumference of the housing 12. The outer surface of the housing 12 
can have various surface treatments such as circumferential grooves or 
knurling which will roughen the surface and provide a suitable gripping 
surface for the user. It is also understood that the depressions 15 could 
also be placed near the end 14 or could be eliminated entirely. 
The housing end 16 includes threads 17 which are sized to accommodate a 
cover or cap 18. When the cap is threaded in position upon the end 16 of 
the housing 12, a sufficient space 19 is provided internally to retain and 
store the pull-cord 28 which is attached to the internal friction ignition 
primer and could also be attached to cap 18. 
The opposite end 14 of the housing 12 includes an internal support sleeve 
23 which has an end flange 24. This end flange contains outwardly 
extending lugs or ears 26 which are usually arranged diametrically 
opposite each other. A centrally positioned bore or channel 27 is provided 
in the end of the sleeve 23 to accommodate the insertion of the safety 
fuse 22. The outer end of the sleeve 23 is sized to slidably fit the inner 
diameter of the housing 12 and hold the sleeve in a rigid position. The 
sleeve 23 is suitably fastened within the housing by an adhesive or other 
attachment which will hold the sleeve and seal the joints to prevent the 
passage of moisture or other contaminants. 
A seal retainer or retaining cap 20 is arranged for mounting on the end 14 
of the housing 12. The retainer 20 is held in position by engaging the 
ears 26 on the flange 24 with the rotation of the retainer 20 causing 
pressure to be applied to an internal sealing device. When the safety fuse 
22 is properly inserted through the opening 30 provided in retainer 20 and 
the channel 27 provided in the sleeve 23, the engagement of the retainer 
20 and the rotation of the retainer with respect to the ears 26 causes the 
retainer to be latched with the result that an internal sealing device 25 
pushes against the safety fuse 22 sealing the opening in the igniter 10 to 
prevent the intrusion of water, gases or contaminants. 
During shipping and storage of the igniter 10, a removable plug 21 having 
an extended shaft with approximately the same diameter as the safety fuse 
is inserted through the opening 30 and channel 27 to engage the sealing 
device 25 and seal the end 14 when the retainer 20 is engaged. In this 
way, with the vent plug 100 and the retainer 20 properly positioned, the 
igniter housing 12 is completely sealed making it water-proof and 
contamination-proof so that the igniter 10 will have an extended shelf 
life and will be functionally reliable when needed for use. 
The retainer 20 as viewed in FIGS. 3-5, includes an outer or front plate 
32, hollow rearwardly extending circular core 36 including the 
longitudinal central opening 30. Side members 38 extend rearwardly from 
the front plate 32 and connected to an enlarged flat circular ring 34. The 
end of the circular core 36 extends beyond the ring 34 a sufficient 
distance to engage the internal sealing device 25 within the support 
sleeve 23. 
The side members 38 of the retainer 20 are cut away leaving openings 40. 
These openings are diametrially opposite on each side of the retainer 20 
and each extend approximately 90.degree. around the circumference of the 
retainer 20. The segments of the cut-a-way openings 40 near the ring 34 
form a circular inclined surface 42 which rises outwardly from the ring 
34. Detents or raised areas 44 can be provided near the ends of the 
inclined surfaces 42 to form a retaining stop to hold the retainer 20 and 
prevent it from rotating or backing off accidentally with respect to the 
ears 26 as will be explained later. 
The interior circular core 36 is spaced inwardly from outer members 38 
which leaves an open area 46 therebetween. The outer diameter of the core 
36 is slightly smaller than the inner diameter of bore 27 provided within 
the retainer sleeve 23. The space 46 is, in turn, sized to receive the 
outer flange 24 with slots 48 which are diametrically opposite, arranged 
to receive the ears 26. The slots 48 are provided in the ring 34 at the 
base of the inclined surfaces 42. In this way, the retainer 20 can be 
inserted over the outer flange 24 with the ears 26 passing through the 
suitably sized slots 48. Once the retainer 20 is inserted so as to engage 
the ears 26 on the inclined surfaces 42 a circular rotation in a clockwise 
direction as viewed in FIG. 2 will cause the ears to move along the 
inclined surface 42 and pass over and across the detents 44. This movement 
moves the end of the core 36 inward against the sealing device 25 provided 
in the bore 27 of the sleeve 23, which in turn, will apply pressure 
against the device causing the sealing function. 
The sealing device 25 that is intended for use with the present invention 
is a double O-ring seal which is positioned within the channel 27. A 
shoulder 29 is formed within the channel 27 at a predetermined distance 
from the outer surface of the flange 24. The two O-rings can be identical 
and are sized to fit the diameter of the channel 27 and the diameter of 
standard safety fuse 22. With the fuse 22 or shipping plug 21 inserted, 
the inward pressure placed on the outer O-ring causes both O-rings seals 
to compress preventing the passage of water or other contaminants. It has 
been found that the double O-ring arrangement described herein provides 
unique results when used with safety fuse which is highly desirable in a 
device of this type. 
To release the internal seal 25 it is merely necessary to rotate the 
retainer 20 in the opposite or counterclockwise direction. This causes the 
ears 26 to pass over the detent 44 which allows it to slide down the 
inclined surface 42 which moves the core 36 outward thus, relieving the 
force on the seal 25. 
It is to be understood that because there is no real necessity in making 
the retainer removable from the housing 12, it is conceivable that the 
slots 48 can be filled or closed once the retainer has been positioned 
over the flange 24 and ears 26. Thus, the retainer can be moved from the 
locked or sealed position to the unlocked position and back without the 
retainer being separated from the housing 12. In this way, the retainer 
will not be lost or misplaced which could expose the interior of the 
housing 12 and render the igniter 10 ineffective. 
The housing 12 is formed as a generally open, hollow elongated cylinder. 
Internally within the housing 12 is a large opening or bore 50 which 
extends approximately two-thirds of the length of the housing and which, 
in turn, narrows to a smaller diameter bore 52 towards the end 16. 
The internal support sleeve 23 includes an enlarged section 54 which ends 
with the flange 24 exposed on the outside of the end 14 of the housing. 
This enlarged portion seals against the interior surface at the end of the 
housing 12 and also contains the internal bore 27 which is sized to 
receive the central core 36 of the retainer 20 and the sealing device 25. 
The sleeve 23 then transitions into an elongated narrow extension portion 
58 which has a smaller diameter than the inside diameter of the housing 
bore 50. In this way, an exhaust vent chamber or cavity 60 is provided 
between the support sleeve 23 and the housing 12. A collet 62 having an 
enlarged end 64 and reduced end 66 is also provided. The outside diameter 
of the enlarged section 64 of the collet 62 is sized to slidably fit 
within the housing bore 50 to a point where it abuts the transition 
between the bore 50 and 52. The outside diameter of the extended end 66 of 
the collet 62 is the same as the support sleeve 23. An internal bore 68 
which has the same diameter as the sleeve extension portion 58 is provided 
within the extending end 66. The bore 68 narrows in a tapered transition 
72 to the bore 70 which passes through the enlarged end 64. At least one 
elongated vent slot 74 is provided along the outer surface of the enlarged 
end 64 of the collet 62. The purpose of this slot will be explained later. 
The functioning components of the weather-proof igniter 10 include a 
friction primer igniter 80 and a pair of ferrules 82, 84. The ferrules can 
be fabricated from thin sheet metal and are of a hollow tubular 
configuration. It has been found through experimentation that a ferrule 
length of approximately 1/2"-5/8" is desirable. One end of each of the 
ferrules is cut in a serrated configuration having a number of sharp 
points or ends. The serrated ends are then crimped or bent inwardly 
slightly to partially close the end of the ferrule. The outer diameter of 
the ferrule is sized to allow the ferrule to slide inwardly through the 
inner bore of the extension 58 of the retaining sleeve 23, and also allow 
safety fuse to be inserted through the barrel of the ferrule. 
If desired, one or more protrusions 86 can be punched in the side of the 
ferrule so that the metal is deformed outwardly from the side in a 
direction which is away from the crimped end of the ferrule. The 
protrusions 86 permit the ferrule to be inserted into the support sleeve 
to the desired position and anchors the ferrule in place. Any force 
applied to the crimped ends 83 of the ferrules 82, 84, respectively will 
cause the protrusions 86 to seat into the material of the sleeve or 
collet, further preventing the ferrules from being moved or dislodged. 
The first ferrule 82 is slidably inserted, crimped end first, into the bore 
59 through the outer end of the extended portion 58 of the support sleeve 
23 to a point where slightly less than half of the ferrule 82 extends 
beyond the end of the sleeve. The second ferrule 84 is then inserted, 
crimped end first, into and through the channel 27 and into the reduced 
bore 59 to a point where the crimped ends of the ferrules are spaced apart 
a predetermined distance. In most cases, this will be approximately 
one-half inch. One or more properly sized metering vent apertures 57 are 
formed through the sides of the extension 58 of the support sleeve 23. 
These holes are positioned at a predetermined distance from the crimped 
end of the first ferrule 82 and at a point ahead of the second ferrule 84. 
The size and positioning of the vent apertures 57 are critical with 
respect to the end of the ferrule 82 as will be explained below. 
The friction primer 80 includes a small metallic cup 90 which has a 
slightly flared end 92 with the opposite end 94 substantially closed. A 
pull-wire 96 is positioned through a hole 98 provided in the closed end of 
the cup 90. The end of the pull-wire 96 which extends beyond the cup 90 
and into the interior of the ferrule 82 is formed in a series of curves or 
undulations 97. The opposite end of the pull-wire 96 extends outwardly 
through the bore 52. A cylindrically shaped vent plug 100 is positioned in 
the end of the bore 52 with one end sticking out into the space 19 
provided within the cap 1 when it is installed. The end of the vent plug 
100 which extends into the space 19, has a hole 104 through which a finger 
grip device 28 such as a pull-cord is attached. The opposite end of the 
vent plug 100 has a reduced diameter section 106 and a transverse hole 
108. The end of the pull-wire 96 is inserted through the hole 108 and is 
twisted back on itself to secure the wire to the plug. 
In order to seal the bore 52 to prevent the introduction of moisture or 
other contaminants a circular groove or shoulder 110 containing an O-ring 
112 is provided within the bore 52. The O-ring 112 is sized to properly 
fit and seal against the vent plug 100. As an alternative, it is possible 
that another larger O-ring seal (not shown) could be either added or 
substituted for the smaller O-ring seal 112 by placing it within the cap 
18 or at the base of the threads 17 on the housing 12. In this way, the 
cap will seal against the larger O-ring when the cap is installed. If the 
smaller O-ring seal 112 is rendered unnecessary, then it is also possible 
that vent plug 100 can be eliminated with the pull-wire 96 attached 
directly to the finger grip 28. 
The friction primer or igniter 80 including the primer cup 90 and pull-wire 
96 is of a type which is well known in the prior art and has been used for 
many years. The interior of the cup 90 can be filled with an ignition 
compound such as potassium chlorate and charcoal. The undulating portion 
97 of the pull-wire 96, in turn, can be coated with a friction-sensitive 
compound such as red phosphorus. 
OPERATION 
The weather-proof safety fuse igniter 10 as shown and described in this 
application is extremely reliable and easy to use. When it is desired to 
ignite the safety fuse, it is merely necessary to turn the retainer 20 to 
the release or unlocked position. The shipping plug 21 is then easily 
removed from the end of the housing 12 and discarded. The safety fuse 22 
is inserted into the opening 30 so that the end passes through the seal 
25, second ferrule 84, and abuts against the crimped end 85 of first 
ferrule 82. By positioning the end of the fuse 22 adjacent to the crimped 
end 83 of the first ferrule 82, the fuse is properly positioned with 
respect to the friction primer 80 and is aligned to receive the directed 
flame generated in the igniter cup 90. In addition, the sharp points on 
the crimped end 85 of the second ferrule 84 retains the safety fuse 22 and 
prevents it from being accidentally withdrawn from the housing prior to or 
during ignition. 
With the safety fuse 22 in position the retainer 20 is turned in the 
opposite direction to the locked position whereby the core 36 is pushed 
against the seal 25 to compress the seal against the internal support 
sleeve 23 and the outer sheath of the safety fuse 22. In this way, the end 
of the housing 12 is completely sealed to prevent the introduction of 
water or other contaminants. When it is desired to ignite the fuse, the 
cap 18 is removed and discarded. The pull-cord 28 is then grasped and 
pulled sharply outward and away from the end 16 of the housing 12. This 
removes the vent plug 100 from the bore 52 as well as drawing the 
pull-wire 96 through the primer cup 90. This motion causes the friction 
compound to ignite the primer material causing an intense flame to be 
generated which is directed through the ferrule 82 and against the exposed 
end of the safety fuse 22. The intense and concentrated flame front causes 
reliable ignition of the safety fuse 22 which through burning creates a 
considerable volume of exhaust gases. The vent apertures 57 in the support 
sleeve 23 meters the gases and allows these gases to quickly dissipate 
from the burning area. The gases pass outwardly through the exhaust 
chamber 60 surrounding the sleeve 23, through the slot 74, and out to the 
atmosphere through the bore 52. The size and placement of the exhaust 
apertures 57 as previously stated, are important to premote the reliable 
ignition and burning of the safety fuse. The inadequate venting of the 
exhaust gases can create a high internal pressure which can cause the fuse 
to be extinguished or cause the igniter to be damaged. On the other hand, 
it is possible that free and open venting of the burning gases can create 
a negative pressure around the end of the fuse which could actually cause 
the powder within the fuse to be extracted causing the fuse, in turn, to 
be extinguished. 
Although a disposable weather-proof igniter for safety fuse has been shown 
and described in this application, it should be understood that this 
invention is not to be limited to the exact form disclosed, and changes in 
detail and construction of the invention may be made without departing 
from the spirit thereof.