US3762327A

US3762327A - Pyrotechnic devices

Info

Publication number: US3762327A
Application number: US00034306A
Authority: US
Inventors: D Murray; G Curtis
Original assignee: Pains Wessex Ltd
Current assignee: Pains Wessex Ltd
Priority date: 1970-05-04
Filing date: 1970-05-04
Publication date: 1973-10-02
Anticipated expiration: 1990-10-02

Abstract

A signal device operable under water and released to rise to and burn at the surface, has a casing open at one end, signal composition therein, igniting means therefor, and plug means for inhibiting passage under water between the open end and the signal composition which permits the escape of combustion products when the device is initially lighted but which is expelled or consumed when the combustion gases are generated at a higher rate. A fuse imparts delay between operation of the igniting means and ignition of the signal composition.

Description

United States Patent 1191 1111 3,762,327

Murray et al. 1 1 Oct. 2, 1973 1 PYROTECHNIC DEVICES 1102,47? 9/1963 Stefan et 111 .1 102/376 3,566.791 3/1971 Lohkampum 102/32 [75] Dudley 3,051,085 8/1962 Finkelstein 6. 102 37 near sallsbury; Gordon Wilfred 2,119,697 6/1938 Anderson l02/37.8 ux Curtis, Bulford Village, both of England Primary Examiner-Robcrt F. Stahl [73] Assignee: Pains-Wessex Limited, Wiltshire Attorney-Hall and Houghton England [22] Filed: May 4, 1970 [57] ABSTRACT [21 Appl. No.: 34,306 A signal device operable under water and released to rise to and burn at the surface, has a casing open at one end, signal composition therein, igniting means there 2; 25 Q2 23; 4 for, and plug means for inhibiting passage under water I 0 b/' between the open end and the signal composition which permits the escape of combustion products when th l'ht h' l References Cited 6 devlce 1s 1n1t1ally 1g ed but WhlC 1s expe led or consumed when the combustion gases are generated at UNITED STATES PATENTS a higher rate. A fuse imparts delay between operation 2920.560 1/1960 Clauser et a1 102/37.8 X of the igniting means and ignition of the signal compo- 3,29s.311 1/1967 Catlin 102/3778 x 51110 v{103,883 9/1963 Ormanns... l02/39 2,075,813 4/1937 King 102/37.8 X 10 Claims, 2 Drawing Figures PATENTEDBET 2 ms TUDLi) 6. M m,

6 P /v M/ (410175 INVENTOR 5 BY M 2am ATTORNEY PYROTECHNIC DlEVTCES This invention relates to pyrotechnic signal devices, and especially to pyrotechnic signal devices suitable for being operated and released from under water.

The invention provides a pyrotechnic signal device which comprises a casing, one end of which is open, a mass of signal composition contained in the casing, means for igniting the signal composition, and means arranged to plug the casing between the composition and the open end of the casing, the plug means preventing or impeding the passage of water from the open end of the casing to the composition, and being arranged to be expelled from the casing or destroyed by gases of combustion when the pressure of these gases reaches a sufficiently high value, to allow free escape of the combustion products.

The provision of such plug means in a signal device enables devices to be constructed which can be operated under water and released, and which will rise to the surface and burn at the surface. The plug means prevents the amount of water reaching the composition from being great enough to extinguish the combustion before the composition has been properly ignited. When the plug means has been expelled from the easing or destroyed, the combustion gases from the burning composition escape from the open end of the casing and the velocity of the combustion gases from the composition is such that the quantity of water which can enter the casing is insufficient to extinguish the burning of the composition.

Advantageously, at least a portion of the plug means is formed of a water-absorbent material. Advantageously, at least a portion of the plug means that is adjacent to the wall of the casing is formed of a compressible material, enabling a good fit to be achieved between the plug means and the casing. This is especially important when the plug means is being expelled from the casing. The plug means should not, of course, allow a sudden inrush of water towards the composition to occur when it is being expelled.

Advantageously, at least a part of the plug means is formed of felt or like cloth material; alternatively, at least a part of the plug means may be formed of expanded polystyrene, preferably of low density. The said part is preferably the portion of the plug means adjacent to the wall of the casing.

Advantageously, the plug means includes a plate member of cork or card-board which is in contact with the surface of the composition and in close fit with the wall of the casing. It has been discovered that this serves to prevent water extinguishing combustion of the composition when only part of the surface of the composition has been ignited. Preferably, the composition is arranged to be ignited, in operation, through a recess formed in the edge of the plate member, or through an aperture formed in the plate member. Preferably, a mass of igniting material is formed in the aperture or recess.

Advantageously, the igniting means includes a fuse to impart a delay between operating the igniting means and the ignition of the composition. This makes it possible for the device to be fired under water and yet for the signal composition to commence combustion only after the casing containing the composition has reached the surface. A length of conventional Bickford (or safety) fuse may be employed.

Advantageously, the casing is contained in a watertight container, at part of the water-tight container being arranged to be removable or rupturable in response to the gases of combustion generated to allow egress of the combustion products. With such an arrangement, a signal device may be carried under water for relatively long periods without fear of prejudicing the effectiveness of the device in operation. Preferably, the igniting means is electrically operated and is contained within the water-tight container, and the electric impulse to operate it is applied between two points on the outside of the water-tight container. Such an ar rangement of igniting means is very reliable. Preferably, the plug means includes a number of members formed of felt, which are arranged with their axes parallel to the axis of the casing, and which are each in close fit with the wall of the casing.

Advantageously, the open end of the casing is provided with removable closure means, thereby obviating the need for a separate water-tight container to house the casing. if the igniting means includes a slow burning fuse, this (the fuse) may then extend substantially parallel to the axis of the casing, and the plug means may then include a number of felt washers which each make a close fit with the fuse and with the casing. The use of such felt washers has the advantage that the possibility ofa frame from the priming on the fuse igniting the signal composition prematurely is reduced. The fuse will generally comprise a thin train of gunpowder covered by a layer of textile or like material. Only the actual gunpowder will burn in operation, leaving the casing, so that combustion gases passing down the centre of the fuse with be sufficient to prevent water reaching the composition.

Preferably, the igniting means is arranged to be operated in response to a movement of the closure means relative to the casing which is such that the closure means is not removed from the casing. Such a device may be operated without actually disengaging the closure means from the casing, so that if the device is operated under water, the closure means will remain in engagement with the casing for at least a part of the passage of the device towards the surface. This both prevents any water entering the casing and provides additional buoyancy for the device. The closure means will be removed in due course by the pressure of the combustion gases generated. If the user accidentally removes the closure means completely from the casing in operating the device, the igniting means will nevertheless be operated before the closure means is removed, and for many designs of device and applications the device will function normally.

Preferably, the casing and the closure means are each tubular. As an additional precaution against the ingress of water into the casing, a sealing band of flexible material may be provided for surrounding the join between the casing and the closure means to provide a watertight seal, the arrangement being such that the join is surrounded by the band both before and after the movement of the closure means that operates the igniting means.

Alternatively, the igniting means may be arranged to be operated in response to removal of the closure means. This arrangement will only generally be feasible in shallow water.

The igniting means advantageously comprises a percussion cap and a striker mechanism for striking the cap, the striker mechanism preferably being arranged to be operated by movement of the closure means relative to the casing. The striker mechanism is preferably located towards the open end of the casing, and a water-tight seal formed between the wall of the casing and the body of the striker mechanism. The plug means, in this case, includes the body of the striker mechanism and the material which forms the seal between the body of the striker mechanism and the inner wall of the easing. The location of the striker mechanism in this way has the advantage that a region of reduced diameter, formed by the interior of the body of the striker mechanism, is formed towards the lower end of the casing, and combustion gases passing out of the casing through this region of reduced diameter will tend to prevent or reduce the quantity of water entering the casing. This allows signal devices which are operated in response to the removal of the closure means to be used at lower depths. Also, this provides an additional precaution against the ingress of water when devices in which the igniting means is operated by moving the closure means relative to the casing but without disengaging the closure means are mis-handled by the user accidentally removing the closure means when operating the device.

The signal composition is preferably a composition that produces a substantial quantity of gas on combustion. The quantities of gas produced by such compositions are such that the signal device is made more buoyant in operation. The composition may be a smokeproducing composition or a flare-producing composition.

Two pyrotechnic signal devices, constructed in accordance with the invention, will now be described in detail, by way of example, with reference to the accompanying drawings, in which:

FIG. l is an axial cross-section of the first signal device, and

FIG. 2 is an axial cross-section of the second signal device.

Like reference numerals are given to like parts in both drawings. Both signal devices are suitable for being operated and released from under water.

Referring to FIG. I, the first signal device, which is a signal flare device, comprises a tubular metal casing l, which is closed at one end and open at the other, and a mass of flare composition 2 housed in the casing adjacent to its closed end. A tubular closure member, indicated generally by the reference numeral 3, which is in external sliding fit with the casing ll, closes the open end of the casing, and a rubber sealing band 4 serves to make the join between the open end of the clousre member and the casing water-tight. The closure member 3 is formed on the outside with a number of circumferential ribs 5, which enable it to be firmly gripped.

The ignition means of the signal flare device incorporates a percussion cap (not shown) and an un-cocked percussive striker mechanism, indicated generally by the reference numeral 6, which is similar to the striker mechanism described in British Pat. application No. 26370/68. The striker mechanism 6 is operated by withdrawing a spring-loaded plunger 7 from the casing 8 of the mechanism against the action of the spring. When the plunger 7 has been withdrawn far enough, it is released from the casing 8, and a member moves under the action of the spring and strikes the percussion cap.

The plunger 7 is connected by means of a length of cord 9 to a screw it) formed in the base of the closure member 3. (In order to secure the cord 9 to the screw 10 during manufacture of the device, the cord is passed through the hole in the base of the closure member 3, secured to the screw 10, and the screw 10 is then screwed into the hole.) The casing 8 of the striker mechanism is located in position at its upper end by a hollow cylindrical member 11 formed with projections 12 which engage with recesses formed in the casing 8 of the striker mechanism. The hollow cylindrical member 11 is located in position in the casing l by means of an annular sealing member 13, which fits tightly around the cylindrical member 11, and which is in close fit with the casing. Relative axial movement be tween the sealing member 13 and the casing 1 is prevented by a circumferential rib 14 in the casing which engages a recess in the sealing member. The igniting mechanism is operated by moving the closure member 3 away from the casing 1, the movement of the closure member causing retraction of the plunger 7 from the casing 8.

The upper end of the hollow cylindrical member 11 is formed with a portion 15 of reduced diameter, through which passes a Bickford fuse 16. The fuse is secured in a ferrule 16a at its lower end. The fuse is iginited by the flame which emanates from the percussion cap when it is struck.

The fuse to is surrounded by a number of felt washers 17 which, together with the fuse itself, plug the casing between the open end and the composition 2, thereby tending to prevent or impede the passage of water from the open end of the casing to the composition. The washers 117 are in close fit with both the fuse 16 and the wall of the casing 1. The washers 17 also serve to reduce or eliminate the possibility of a flame from the percussion cap or from priming on the fuse to directly striking the composition 2 and igniting it in advance of the main flame front.

The upper end of the fuse 16 is sealed by adhesive tape 18 to a capsule of igniting material 19, which is directly in contact with a mass of priming composition 20 formed at the lower end of the mass of flare composition 2. Thus ignition of the fuse causes ignition of the flare composition 2. A cork washer 21, which surrounds the capsule of igniting material 1) and which is in contact both with the upper washer l7 and the flare composition 2, allows combustion to proceed over that area of the composition which is in contact with the washer without interference from any water which may have entered the signal device.

I The walls of the casing l are lined with an inhibiting layer in the form of a layer of paper 22, which prevents the heat from the combustion adversely affecting the casing and minimizes heat transfer down the sides of the composition 2 in advance of the flame front. It has been found that the layer of paper 22 also improves the reliability of combustion of the signal device.

The flare composition 2 is formed of the following components, the parts being by weight:

15 parts This composition will combust to produce a red flame.

in operation, when the device is operated under water, the closure member 3 is moved in an axial direction away from the casing through a distance sufficient to cause the striker mechanism to operate. The length of the cord 9, and the distance which the plunger 7 must be retracted before it is released are such that this distance is not sufficient for the closure member 3 to be disengaged from the casing l; the sealing band protects the join between the casing and the closure means after the striker mechanism has been operated.

The closure member 3 remains in engagement with the casing l for at least a part of the upward passage of the device towards the surface. Any water which may leak into the closure member 3 through the join between the'closure member 3and the casing tends to be prevented from entering the casing by virtue of the stream of combustion gases emanating through the easing 8 of the striker mechanism 6 which forms a region of reduced cross-sectional area and hence of increased gas velocity.

When the fuse to has burned fully, and the composition 2 has been properly ignited, the closure member 3 is displaced from the casing 11 by the combustion gases from the composition, and the igniting mechanism 6 and the

members

11 and 13 holding it in position are ejected from the casing 1 by the combustion gases, together with the felt washers 17, the spent fuse l6 and cork disc 21. As the washers 17 are being ejected, they are compressed slightly axially by the gas pressure, and the resulting radial expansion, together with the absorption of water by the washers, tends to prevent the sudden inrush of water impinging on, and extinguishing the combustion of the composition. When the washers 17 have been expelled from the casing, the velocity of the combustion gases leaving the end of the casing is sufficient to prevent the quantity of water entering the casing being great enough to extinguish the composition, and thus the composition is not extinguished even if the device has not reached the surface of the water by this time.

When the device reaches the surface, the free escape of combustion products from the composition 2 into the atmosphere then takes place.

if the user accidentally removes the closure member 3 from the casing l in operating the device, the combustion will not be extinguished provided the depth at which the device is operated is not too great, since the percussion cap will have been ignited before the closure member 3 is completely removed, and the gases venting through the casing 6 of the striker mechanism 8 will prevent the quantity of water that enters being great enough to extinguish the combustion.

The second signal device is also a signal flare device and comprises a casing 1 housing signal composition 2 having the same composition as in the first signal device.

The casing l is supported by means of foam plastic 23 in an upper compartment 24 of a container indicated generally by the reference numeral 25. The upper compartment 24 is water-tight, and is closed at the top by a push-seal cap 26, which has an O-ring 27 extending around its circumference.

The signal device is electrically operated, and the electric impulse is supplied to two

screws

28 and 29 via the lower compartment 301* of the container 25 by means which are not shown. Wires pass from the

screws

28 and 29 to an electric fuse 31, which comprises a wire passing through a composition which ignites when a suitable current passes through the wire. The electric fuse 31 ignites a delay fuse 32, which extends through an aperture in the wall of the casing 1, and which in turn ignites a mass of priming composition 33 which is in contact with the composition 2. Thus the composition is ignited by applying a suitable electric impulse between the

screws

28 and 29.

The priming composition 33 is surrounded by a cardboard washer 34 which is in contact with the surface of the composition 2, and which performs the same function as the cork washer 21 in the first device. The upper part of the casing 1 is plugged by a number of felt discs 35. The felt discs 35 above the delay fuse 32 each make a good fit with the wall of the casing It When the device is operated and released from under water, an electric impulse is applied to the

screws

28 and 29, and the electric fuse 31 ignites the delay fuse 32. The pressure rise in the compartment 24 due to the combustion gases generated will, in due course, cause the push-seal cap 26 to be displaced. The container 25 will have reached the surface of the water by this time.

The felt discs 35 will prevent the quantity of water entering the casing 1 from being large enough to extinguish the combustion and, when the composition 2 has ignited properly, the pressure of the combustion gases generated will be such as to expel the discs 35 from the casing l. The free escape of combustion products from the casing 1 then takes place.

We claim:

1. A pyrotechnic device for underwater use comprising:

a. a casing having one open end,

b. a mass of signal composition in said casing,

c. signal composition igniting means, and

d. plug means plugging said casing between said signal composition and said open end of said casing to prevent or impede the passage of water to said signal composition, said plug means being formed to permit the escape of combustion products when said device is initially ignited but to be expelled from said casing or be consumed by the combustion gases when said combustion gases are generated at a higher rate,

and wherein:

e. said signal composition igniting means includes a fuse to impart delay between the operation of said igniting means and the ignition of said composition, said fuse extending substantially parallel to the axis of said casing, and

f. said plug means includes a number of felt washers, said washers having a close fit with said fuse and with the inner surface of said casing.

2. A signal device according to claim 1, wherein:

g. removable closure means is provided for said open end of said casing, and

h. said igniting means is operable in response to a movement of said closure means relative to said casing which is such that said closure means is not removed from said casing.

3. A signal device according to claim 2, wherein:

i. said casing and said closure means are each tubular and in sliding fit with each other, and

j. a sealing band of flexible material surrounds the joint between said casing and said closure means to thereby provide a water-tight seal, said band surrounding said joint before and after said movement of said closure means that operates said igniting means.

4. A pyrotechnic signal device for underwater use comprising:

a. a casing having one open end,

b. a mass of signal composition in said casing,

c. Signal composition igniting means,

(1. a removable waterproof closure to prevent water entering the open end of the casing, said closure being readily removable in response to the pressure of combustion gases generated when said device is ignited,

e. plug means plugging said casing between said signal composition and said open end of said casing to prevent or impede the passage of water to said signal composition, and

f. at least a portion of said plug means being compressible and in tight fit with the wall of said casing to tend to retain said plug means in said casing, said plug means being formed to permit the escape of combustion products when said device is initially ignited, whereby said closure but not said plug means becomes removed, but to be expelled from said casing or be consumed by the combustion gases only when said combustion gases are generated at a higher rate, said compressible portion of said plug means remaining in e. close fit with the wall of said casing while being expelled from said casing.

5. A signal device as claimed in claim 4, wherein g. said signal composition igniting means includes a fuse,

h. said fuse extends through a passageway terminating adjacent the surface of the composition, and

i. said compressible portion of said plug means comprises a number of felt discs between said signal composition and said open end of said casing, said felt discs being arranged with their axes parallel to the axis of said casing and being in close fit with the wall of said casing.

6. A signal device as claimed in claim 5, wherein:

j. said passageway extends from adjacent the surface of said signal composition through said plug means.

7. A signal device as claimed in claim 5, wherein:

j. said passageway extends through said casing adja cent the surface of said signal composition.

8. A signal device as claimed in claim 7, wherein:

k. said fuse is electrically ignited,

i. said device further comprises a water-tight container housing said fuse and said casing, and

m. said container is closed by said waterproof closure.

9. A signal device as claimed in claim 4, wherein:

g. said plug means includes a plate-like member, said plate-like member being maintained by said compressible portion of said plug means in contact with the surface of said composition to be ignited,

h. said plate-like member has an opening therein to permit ignition of said composition therethrough,

i. said signal composition igniting means includes a fuse, and

j. said signal composition igniting means further includes a mass of igniting material positioned adjacent an end of said fuse and adjacent said opening to thereby facilitate the spreading of combustion over that area of said signal composition with which said plate-like member is in contact.

10. A pyrotechnic signal device for underwater use comprising:

and wherein e. a portion of said plug means is compressible and has a close fit with the wall of said casing while being expelled from said casing,

f. the open end of said casing is provided with removable closure means,

g. said igniting means comprises a percussion cap and a striker means for striking said cap, said striker means being operable to strike said cap in response to a movement of said closure means relative to said casing,

h. said striker means being located toward said open end of said casing and displaceable therefrom with said plug, and forming a watertight seal between its body and the wall of said casing before such displacement, and

i. the body of said striker mechanism defining an outlet of reduced cross-sectional area before such displacement.

Claims

1. A pyrotechnic device for underwater use comprising: a. a casing having one open end, b. a mass of signal composition in said casing, c. signal compositioN igniting means, and d. plug means plugging said casing between said signal composition and said open end of said casing to prevent or impede the passage of water to said signal composition, said plug means being formed to permit the escape of combustion products when said device is initially ignited but to be expelled from said casing or be consumed by the combustion gases when said combustion gases are generated at a higher rate, and wherein: e. said signal composition igniting means includes a fuse to impart delay between the operation of said igniting means and the ignition of said composition, said fuse extending substantially parallel to the axis of said casing, and f. said plug means includes a number of felt washers, said washers having a close fit with said fuse and with the inner surface of said casing.

2. A signal device according to claim 1, wherein: g. removable closure means is provided for said open end of said casing, and h. said igniting means is operable in response to a movement of said closure means relative to said casing which is such that said closure means is not removed from said casing.

3. A signal device according to claim 2, wherein: i. said casing and said closure means are each tubular and in sliding fit with each other, and j. a sealing band of flexible material surrounds the joint between said casing and said closure means to thereby provide a water-tight seal, said band surrounding said joint before and after said movement of said closure means that operates said igniting means.

4. A pyrotechnic signal device for underwater use comprising: a. a casing having one open end, b. a mass of signal composition in said casing, c. signal composition igniting means, d. a removable waterproof closure to prevent water entering the open end of the casing, said closure being readily removable in response to the pressure of combustion gases generated when said device is ignited, e. plug means plugging said casing between said signal composition and said open end of said casing to prevent or impede the passage of water to said signal composition, and f. at least a portion of said plug means being compressible and in tight fit with the wall of said casing to tend to retain said plug means in said casing, said plug means being formed to permit the escape of combustion products when said device is initially ignited, whereby said closure but not said plug means becomes removed, but to be expelled from said casing or be consumed by the combustion gases only when said combustion gases are generated at a higher rate, said compressible portion of said plug means remaining in e. close fit with the wall of said casing while being expelled from said casing.

5. A signal device as claimed in claim 4, wherein g. said signal composition igniting means includes a fuse, h. said fuse extends through a passageway terminating adjacent the surface of the composition, and i. said compressible portion of said plug means comprises a number of felt discs between said signal composition and said open end of said casing, said felt discs being arranged with their axes parallel to the axis of said casing and being in close fit with the wall of said casing.

6. A signal device as claimed in claim 5, wherein: j. said passageway extends from adjacent the surface of said signal composition through said plug means.

7. A signal device as claimed in claim 5, wherein: j. said passageway extends through said casing adjacent the surface of said signal composition.

8. A signal device as claimed in claim 7, wherein: k. said fuse is electrically ignited, l. said device further comprises a water-tight container housing said fuse and said casing, and m. said container is closed by said waterproof closure.

9. A signal device as claimed in claim 4, wherein: g. said plug means includes a plate-like member, said plate-like member being maintained by Said compressible portion of said plug means in contact with the surface of said composition to be ignited, h. said plate-like member has an opening therein to permit ignition of said composition therethrough, i. said signal composition igniting means includes a fuse, and j. said signal composition igniting means further includes a mass of igniting material positioned adjacent an end of said fuse and adjacent said opening to thereby facilitate the spreading of combustion over that area of said signal composition with which said plate-like member is in contact.

10. A pyrotechnic signal device for underwater use comprising: a. a casing having one open end, b. a mass of signal composition in said casing, c. signal composition igniting means, and d. plug means plugging said casing between said signal composition and said open end of said casing to prevent or impede the passage of water to said signal composition, said plug means being formed to permit the escape of combustion products when said device is initially ignited but to be expelled from said casing to be consumed by the combustion gases when said combustion gases are generated at a higher rate, and wherein e. a portion of said plug means is compressible and has a close fit with the wall of said casing while being expelled from said casing, f. the open end of said casing is provided with removable closure means, g. said igniting means comprises a percussion cap and a striker means for striking said cap, said striker means being operable to strike said cap in response to a movement of said closure means relative to said casing, h. said striker means being located toward said open end of said casing and displaceable therefrom with said plug, and forming a watertight seal between its body and the wall of said casing before such displacement, and i. the body of said striker mechanism defining an outlet of reduced cross-sectional area before such displacement.