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Патент USA US3095834

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July 2, 1963
Filed Oct. 21, 1960
2 Sheets-Sheet 1
r1 2
July 2, 1963
Filed Oct. 21, 1960
2 Sheets-Sheet 2
United States Patent 0 '
device more suitable for higher pressures. In FIGURE
3, all components are as described for FIGURE 1, except
that the effect of hydrostatic pressure is indicated.
The operation of the assembly of this invention is as
follows. When the unit is to be used, locking pin 10 is
removed to release piston 8. When the unit is then sub
William R. Brockway, Thorofare, Frank A. Loving,
Wenonah, and George A. Noddin, Sewell, N.J., assign
ors to E. I. du Pont de Nemours and Company, Wil
mington, Del., a corporation of Delaware
merged, increasing hydrostatic pressure encountered with
increasing depth forces piston 8 inwardly of shell 1 against
the pressure of the air entrapped within the shell, and,
Filed Get. 21, 1960, Ser. No. 64,087
3 Claims. (Cl. 102-70)
The present invention relates to initiators and more par
ticularly to pressure-responsive initiators.
10 in the case of the embodiment shown in FIGURE 2,
For activities in which the detonation of explosive
charges below the surface of a body of water is desired,
such as for seismic exploration, underwater signalling,
echo-ranging for detection purposes, and destruction of 15
undersea craft, the need exists for a reliable and accurate
initiator, responsive to the hydrostatic pressure of the
water at some predetermined depth. The availability of
such initiator obviates the need for wires leading from the
Patented July 2, 1963
against the resistance of coil spring 13. As the inward
movement continues, the end of striker arm 11 comes into
contact with arrester 12. When the striker arm has
moved inwardly su?‘iciently for the end to clear arrester
12, the end snaps onto the igniting charge 7, which, being
percussion-sensitive, becomes ignited and in turn initiates
priming charge 3 which then sets off base charge 2.
The pressure at which the striker arm is released from
the arrester is dependent upon a number of factors, such
surface to the charge or for timing devices to cause ac 20 as the weight of the piston, the length of the air chamber
tuation of an initiator.
A number of mechanical pressure-responsive devices for
actuating a ?ring pin are known; these devices possess the
between the piston and the anvil, the frictional resistance
of the piston to inward movement, the stiffness of the
striker arm, and, when an additional spring is present, the
disadvantages of being relatively bulky, expensive, and
strength of this spring. Thus, by proper selection of the
subject to mechanicalfailure. Propagation detonators ac 25 appropriate factors, a pressure-responsive initiator can be
tuated by the collapse of the shell are commercially avail~
produced to be actuated upon arrival at any preselected
able; these devices function reliably only when subjected
to a pressure surge such as from the detonation of a near
The striker arm used in the proposed device is attached
by explosive charge and are not reliable in shallow depths.
at one end to the piston, the free end is pointed towards
Accordingly, an object of this invention is to provide an 30 the side wall of the shell and is aligned with the arresting
economical, reliable and accurate pressure-responsive ini
element. Since the striker arm does not rest on the arrest
ing element, there is no tension exerted on the arm when
The foregoing object is achieved in accordance with this
there is no hydrostatic pressure on the detonator. This
invention by providing a pressure-responsive initiator com
absence of tension not only makes the detonator very
prising a tubular shell integrally closed at one end, and
reliable because the striker arm does not change in its
arranged in succession from said closed end a base det
resistance to bending, but also places the detonator in a
onating charge, a priming charge, an anvil, and a percus
safe condition for handling. The fact that the striker
sion-sensitive ignition charge, said anvil having an aper
arm rests on the arresting element when pressure is exerted
ture leading from said ignition charge to the priming
until the critical point is reached allows a quick release of
charge; ‘a transversely movable piston sealing the open end 40 striking energy to set off the percussion-sensitive pellet
of the shell, a ?exible striker arm fastened to the inner end
of the piston, the striker arm preferably being curved so
that the free end is pointed toward the side wall of the
shell, and an arresting element aligned with the free end
of the striker arm between the free end and the ignition
charge, whereby the free end is prevented from contacting
the ignition charge until the inward movement of the
piston as the result of increased external pressure is su?i~~
cient to bend the striker arm to a degree that the free end
The following examples serve to illustrate speci?c em
bodiments ‘of the present invention. All pressures were
measured on a 2-pound increment pressure gauge.
Example I
Twenty-?ve detonators similar to that shown in FIG
URE 1 were prepared, and ?red by submerging them in
water which was under nitrogen pressure. The detonator
slips off the arresting element and snaps onto the ignition 50 was constructed as follows: The tubular container con
sisted of a gilding metal shell having an inner diameter
of 0.5 inch and a length of 2.4 inches; the anvil was
Preferred embodiments of the present invention are
cold rolled steel; the piston was cold rolled steel with a
illustrated in the accompanying drawings. In the draw
length of 0.375 inch; the safety pin consisted of a length
ings, FIGURE 1 represents a sectional view of an em
bodiment of the present invention, FIGURE 2 represents 55 of 0.059 inch diameter steel wire. The striker arm was
0.029 inch diameter spring steel a length of 0.687 inch,
a sectional view of an alternative embodiment and FIG
URE 3 represents a sectional view of the embodiment of
FIGURE 1 when subjected to hydrostatic pressure.
Referring now to the ?gures in greater detail, in FIG
?at on top with a 0.156 inch radius curve, followed by a
straight length of a 0.125 inch radius curve and termi
nating in a straight length 0.125 inch long, the tip of which
URE l, 1 represents a metal shell integrally closed at one 60 is aligned 0.062 inch above the arresting element. The
percussion-sensitive mixture used was an adhesive-backed
end, 2 is a base charge of a detonating explosive, 3 is a
toy cap.
priming explosive charge, and 4 is an anvil locked in the
shell by peripheral crimp 5. A portion of priming charge
3 is contained within the transverse aperture 6 of anvil
The percussion-sensitive composition ?red in all 25
The range of pressures at which detonation oc
4, and positioned on top of anvil 4 adjacent to aperture 65 curred as from 74-94 and the average pressure
was 81.4
6 is igniting charge 7 of a percussion-sensitive explosive.
integrally formed at one edge of anvil 4 is a striker arm
arrester 12 for striker arm 11 attached to piston 8 located
Example II
Ten detonators were prepared and ?red as in Example
at the open end of shell 1. A pair of rings 9 seal the pis
I except that the anvil was 0.062 inch higher than the
ton and pin 10 locks it in place.
70 above. A mixture of 75% lead salt of dinitro orthocresol,
In FIGURE 2, the components are as in FIGURE 1
20% potassium chlorate, and 5% selenium was placed
except that coil spring 13 has been added, providing a
in the hole of the anvil, an additional ignition mix of
% boron/red lead was added below the anvil and a 0.375
inch long lead carrier was added containing 11.5 grains
per foot lead azide in the center as a base charge. The
range of pressure at which ?ring occurred was from 58-70
a tubular shell integrally closed at one extremity, a piston
slidably mounted within and closing the other extremity
of said shell, a base charge of detonating explosive and
a priming charge of explosive sequentially positioned from and the average was 64
Cl said integrally closed extremity, an anvil positioned con
tiguous to said priming charge, said anvil comprising a
As can be seen from the examples, the proposed deto
‘diaphragm secured in peripheral engagement with the
nator ?res very reliably. The shots in the ?rst series of
tests ?red within a range of 20 and in the sec
inner wall of said shell and a striker arm arrester extend
0nd, of 12 The pressure-sensitive detonators of
ing from said diaphragm toward said piston, said dia
alignment with the arresting device by the locking pin
means for locking said piston in position.
phragm being provided with an aperture therethrough
the prior art ?re within a range of 50
adjacent said striker arm arrester, an ignition charge ?ll
The anvil and arresting device may be of any design,
ing said aperture, a percussion sensitive explosive cap se
straight or irregular, wherein the arresting device holds
cured on said diaphragm adjacent said aperture and in
the striker arm until critical pressure is reached and where
propagating relationship to said ignition charge, a striker
in the striker arm can snap off the arresting ‘device down
arm secured to said piston and extending to engage said
onto the percussion-sensitive mixture. The arresting de
arrester, said arm being adapted to disengage said ar
vice may be annular or occupy only a portion of the inner
rester and strike said percussion cap upon exertion of a
periphery of the shell.
predetermined pressure by said piston, and removable
In the latter embodiment, the striker arm is kept in
until the device is ready to be used.
The normal fric
tion of the sealing rings is su?icient ‘to prevent rotation
when pressure is applied.
2. The initiator of claim 1 wherein a spring means is
interposed between said piston and said anvil.
3. The initiator of claim 1 wherein said striker arm is
a ?exible striker arm of resilient material.
The striker arm is preferably made of a spring steel,
although it may be of a material of sufficient resiliency
References Cited in the ?le of this patent
to snap onto the percussion-sensitive material after it
is moved past its contact with the arrester.
The materials of the shell, anvil or compression spring
Von Gortz ____________ __ Feb. 2, 1902
are not critical and any conventional ignition, base, or
Taylor ______________ __ Nov. 11, 1924
percussion-sensitive composition can be used in the device.
Rasmussen __________ __ Apr. 16, 1946
Although the present invention has been described in 30 2,547,820
Hammer ____________ __ Apr. 3, 1951
detail in the foregoing, it will be apparent to those skilled
McCaslin ____________ __ Sept. 18, 1956
in the art that many variations are possible without de
Diels _______________ __ Aug. 26, 1958
parture from the scope of the invention. We intend,
Hardwick ____________ __ Sept. 9, 1958
therefore, to be limited only by the following claims.
1. A pressure responsive initiator for detonation of
explosive charges at a predetermined depth below the
surface of a body of water which consists essentially of
Great Britain ________ __ May 15, 1919
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