U.S. patent number 3,575,114 [Application Number 04/753,260] was granted by the patent office on 1971-04-13 for time delay antidisturbance faze.
Invention is credited to Robert H. Forster, Bernard M. Jones, Harry C. Loyal, Donald G. Quist, Gaylon L. West.
United States Patent |
3,575,114 |
Quist , et al. |
April 13, 1971 |
TIME DELAY ANTIDISTURBANCE FAZE
Abstract
A fuze having an electronic arming delay timer, an
antidisturbance firing mechanism, and a mechanical clock timer to
detonate the fuze after a prescribed period of time if the
antidisturbance firing mechanism is not actuated.
Inventors: |
Quist; Donald G. (China Lake,
CA), Forster; Robert H. (China Lake, CA), West; Gaylon
L. (China Lake, CA), Loyal; Harry C. (China Lake,
CA), Jones; Bernard M. (China Lake, CA) |
Assignee: |
|
Family
ID: |
25029879 |
Appl.
No.: |
04/753,260 |
Filed: |
August 16, 1968 |
Current U.S.
Class: |
102/220;
102/265 |
Current CPC
Class: |
F42C
15/40 (20130101); H03K 3/351 (20130101); F42C
11/06 (20130101); H03K 17/292 (20130101) |
Current International
Class: |
F42C
11/06 (20060101); F42C 15/00 (20060101); F42C
15/40 (20060101); H03K 3/00 (20060101); H03K
17/292 (20060101); H03K 3/351 (20060101); H03K
17/28 (20060101); F42C 11/00 (20060101); F42c
011/06 () |
Field of
Search: |
;102/82,70.2,71
;307/293,273,301 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pendegrass; Verlin R.
Claims
We claim:
1. A fuze comprising:
means to initiate electrical timing means;
electrical timing means to delay arming of the fuze for a first
interval of time, during which time said arming is prevented;
means to prevent firing of the fuze prior to the end of said first
interval of time;
means for simultaneously arming the fuze at the end of said first
period of time and preventing further current drain to the
electrical timing means;
antidisturbance means for detonating the fuze at any time after the
first interval of time; and
mechanical timing means to detonate the fuze after a second
interval of time which interval is longer than said first interval
of time.
2. The system of claim 1 wherein said electrical timing means to
delay arming comprises:
a first unijunction transistor relaxation oscillator having a short
time constant;
a second unijunction transistor relaxation oscillator having a time
constant approximately equal to the arming delay time;
means for coupling the first and second oscillator so that the
output of the first oscillator lowers the breakdown voltage of the
unijunction transistor of the second oscillator to ensure breakdown
of said transistor at the end of a period equal to one time
constant.
3. The system of claim 2 wherein said means to prevent firing of
the fuze prior to the end of said first interval of time
comprises:
a silicon-controlled switch which grounds the firing circuit upon
initiation of said electrical timing means; and
removes said ground upon receiving an output pulse from the
electrical timing means.
4. The system of claim 3 wherein said silicon-controlled switch
operates a transistor switch which cuts off current to the
electrical timing means in response to an output pulse from the
electrical timing means.
5. The system of claim 4 wherein the antidisturbance means for
detonating the fuze comprises:
a switch capable of firing a properly biased silicon-controlled
rectifier which will detonate the fuze.
6. The system of claim 5 wherein the antidisturbance switch is a
trembler switch.
7. The system of claim 6 wherein the mechanical timing means for
detonating the fuze comprises:
a pair of contacts which when closed are capable of firing a
properly biased silicon-controlled rectifier which will detonate
the fuze; and
the pair of contacts are closed by a clock timer.
Description
BACKGROUND OF THE INVENTION
It is desirable to have a fuze that can not detonate during
handling, and once armed, is not capable of being disarmed.
Such a fuze should additionally provide a safety feature which
would delay arming for a preselected period of time after the means
for arming are initiated. After arming is achieved, the fuse should
detonate if an attempt to move it is made prior to the prescribed
detonation time.
SUMMARY OF THE INVENTION
In accordance with the present invention, an electronic timer in
the form of a dual unijunction relaxation oscillator is initiated.
At the conclusion of the timing cycle, the dual unijunction timer
triggers a silicon-controlled switch which removes a shunt placed
across a firing capacitor and simultaneously turns off a transistor
switch. The transistor switch prevents further current drain by the
arming timer.
The firing capacitor is now permitted to charge, and when it
becomes sufficiently charged, the fuze is armed and ready for
detonation.
Detonation will occur in response to the movement of the trembler
switch.
A mechanical clock having a time constant considerably longer than
the time constant of the dual unijunction relaxation oscillator is
started simultaneously with the unijunction oscillator. The clock
has contacts which close upon completion of its cycle. These
contacts are placed in parallel with the trembler switch so that
the clock will cause detonation at the end of its cycle.
In response to the trembler switch or the clock, the firing
capacitor triggers a silicon-controlled rectifier which applies the
charge on the firing capacitor to a squib to cause detonation.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a block diagram of the system;
FIG. 2 is a "time-line" of the operation of the system shown in
FIG. 1; and
FIG. 3 is a schematic diagram of the electronic circuitry of the
system of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, upon closing of switch S.sub.1 an electronic
arming timer 11 and timer 23, which may be a mechanical clock,
being their timing cycles at time t.sub.0 as shown in FIG. 2.
During the time interval from t.sub.0 until t.sub.1 power cutoff 10
supplies power to timer 11, and power clamp 12 prevents accidental
detonation by circuit 13.
At time t.sub.1 timer 11 triggers power clamp 12, which in turn
causes power cutoff 10 to prevent further current from voltage
source V.sub.1 to flow to timer 11 and arms circuit 13 to permit
detonation.
Timer actuation 23, which may be a mechanical clock, is set to
cause detonation via firing circuit 27 at a prescribed time,
t.sub.3, occurring after time t.sub.0. If the fuze is distributed
during the time interval from t.sub.1 until t.sub.3 an
antidisturbance actuation means, which may be a trembler switch,
will cause detonation via firing circuit 27 at time t.sub.2.
FIG. 3 is a schematic diagram of the system just prior to time
t.sub.0. For the sake of safety, switch S.sub.2 remains closed
until just prior to time t.sub.0.
To initiate the arming cycle, switch S.sub.1 is closed at time
t.sub.0. Silicon-controlled switch 17 is turned on bringing point
18 to ground. Thus, during the arming cycle point 20 is held at
ground potential to prevent charging of firing capacitor 21 and
accidental detonation. As point 18 is brought to ground, transistor
switch 14 is turned on.
When switch S.sub.1 is closed, therefore, current flows from
voltage source V.sub.1 through transistor switch 14 to dual
unijunction transistor timer 11. Timer 11 comprises a first
unijunction transister relaxation oscillator consisting of
unijunction transistor 16, resistor 31 and capacitor 29; and a
second unijunction transistor relaxation oscillator consisting of
unijunction transistor 15, resistor 30 and capacitor 28.
Unijunction transistor 16 is necessary to achieve a predetermined,
long time delay in the second unijunction transistor relaxation
oscillator.
Upon closing of transistor switch 14, capacitors 28 and 29 begin to
charge through resistors 30 and 31 respectively. The combination of
resistor 30 and capacitor 28 produces a long time constant for the
second relaxation oscillator in comparison to the time constant
resulting from the combination of resistor 31 and capacitor 29.
The potential at the emitter of unijunction transistor 16 will rise
exponentially, in response to the time constant produced by
resistor 31 and capacitor 29, until the breakdown voltage of
unijunction transistor 16 is reached. At breakdown, the emitter
potential drops to zero.
Simultaneously, the emitter potential of unijunction transistor 15
is rising exponentially at a much slower rate in response to the
time constant produced by register 30 and capacitor 28. Resistor 30
is large for the purposes of a high time constant, therefore
unijunction transistor 15 cannot fire because it cannot draw enough
current through resistor 30.
To permit unijunction transistor 15 to fire, the emitter of
unijunction transistor 16 is coupled to the nongrounded base of
unijunction transistor 15. When the potential at the emitter of
unijunction transistor 16 drops to zero, the breakdown voltage of
unijunction transistor 15 is caused to be lowered. Current may now
be drawn from capacitor 28 to fire unijunction transistor 15 at
time t.sub.1.
The firing of unijunction transistor 15 sends an arming pulse into
diode 32 which turns silicon-controlled switch 17 off. Point 18 is
now permitted to charge up to potential V.sub.1. The potential rise
of point 18 places a potential at the base of transistor switch 14
to open the emitter-collector circuit and cut off further current
to electronic arming timer 11.
Zener diode 19 prevents a false trigger pulse resulting from
feedback from the internal impedance of source V.sub.1 from turning
silicon-controlled switch 17 back on. Firing capacitor 21 is thus
permitted to charge to potential V.sub.1. The fuze is now fully
armed and ready for detonation.
Detonation will occur when the potential across firing capacitor 21
is applied, by either trembler switch 22 or clock 23, via Shockly
diode 24 to silicon-controlled rectifier 25. The silicon-controlled
rectifier applies the potential across firing capacitor 21 to a
squib 26 for detonation.
Clock 23 may be a simple mechanical clock having contacts which
close after a predetermined interval, at time t.sub.3.
Shockly diode 24 acts as a level detector to prevent firing of
silicon-controlled rectifier 25 when there is inadequate voltage to
fire squib 26. The breakdown voltage of the Shockly diode is
greater than the minimum voltage necessary to fire the squib 26.
Therefore, if the potential across firing capacitor 21 has not
reached firing potential, a premature disturbance will not cause
insufficient detonation.
The invention described herein may be manufactured and used by or
for the Government of the United States of America for governmental
purposes without the payment of any royalties thereon or
therefor.
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