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Патент USA US3035531

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United States Patent O??cc
Patented May 22, 1962
washer has a low coel‘?cient of friction, and which has
su?icient elasticity to conform to the internal walls of
George H. Hynard, Mundelein, Ill., assignor to Stewart
the cylindrical casing 10 and which will maintain its
elasticity and ?exibility through a wide range of tem
‘ Warner Corporation, Chicago, Ill., a corporation of
Filed June 30, 1955, Ser. No. 519,058
1 Claim. (Cl. 102-702)
A washer 50, having a soldering lug 52 formed integral
therewith, is brazed or soldered to the casing 10. The
casing 10 is completely ?lled with a hydraulic ?uid such
The invention relates generally to electrical switches
as a silicone oil which maintains its viscosity quite uni
and more particularly to a switch for closing or opening 10 form throughout a substantial range of temperature.
a circuit with a predetermined time delay following initia
The manner in which the switch heretofore described
tion of its actuation by the setback or centrifugal force
may be used is illustrated in FIGS. 3 and 4. In FIG. 3
of a projectile discharged from a gun, or by manual re
the switch housing 10 is illustrated as being mounted
lease, assuming a loaded compression spring as the driv
radially within a projectile 60 which is adapted to be
15 ?red from a ri?e, having riding to impart a gyro-rotational
ing medium.
More particularly the invention relates to an improved
effect to the projectile.
switch mechanism for arming the fuze, and hence the
Assuming FIG. 3 represents the outlines of the pro
projectile, in response to the centrifugal force as the
jectile 60, looking from the breech end of the ri?e, the
projectile is discharged from the ri?e, or by the setback
projectile will, upon explosion of its propelling charge,
or inertia force resultant from the discharge of the 20 rotate clockwise.
Within the fuze mechanism of the projectile there may
It is thus an object of the invention to provide an
be provided a source of electrical energy 62, illustrated
improved switch mechanism which is operated by cen
schematically in FIG. 4, which is normally short-circuited
trifugal force, and the operation of which is timed by the
by the switch 22, 30. The circuit includes a resistance
?ow of hydraulic ?uid through an ori?ce.
element 64 which may form part of a detonator or primer
A further object is to provide an improved hydraulically
to initiate the detonation of the projectile. It will be
controlled switch mechanism which is adapted to be oper
apparent that the heating or energization of the resistor
ated by centrifugal force and used in the projectile to de
64 is prevented while the switch 22, 30 is closed.
lay the arming thereof.
As the projectile is propelled from the ri?e and the
Other objects Will appear from the following descrip 30 gyro~rotary twist imparted thereto, the mass of piston
tion, reference being had to the accompanying drawings
32, due to centrifugal force, tends to force the hydraulic
in which—
?uid from the radially outward chamber 70 to the cham
FIG. 1 is an enlarged plan view;
ber 72 through the ori?ce 42. The rate of the transfer
FIG. 2 is a central vertical sectional view taken on the
of the hydraulic ?uid from the chamber 70 to the cham
35 ber 72 may be accurately determined by the size of the
lines 2—-2. of FIG. 1;
FIG. 3 is a diagrammatic base end view of a pro
ori?ce 42, taking into consideration the type and size of
jectile showing the location of the switch therein; and
shell and kind of cannon or ri?e which is to be used to
FIG. 4 is a schematic diagram of a circuit in which
?re the shell.
the centrifugally powered, hydraulically controlled switch
As the centrifugal force acting on the piston 32 causes
may be incorporated.
transference from chamber 70 to chamber 72 of the
Referring to FIGS. 1 and 2, the switch mechanism is
hydraulic ?uid, the resilient ?ngers 22 maintain contact
housed in a generally cylindrical container 10, having an
with the piston stem 30 until shortly before the piston
enlarged outer end portion 12 for reception of an in
reaches the radially outward end wall of the housing 10.
sulating washer 14 comprising a layer 16 of synthetic, oil
Upon opening the switch 22, 30 (FIG. 4), the full out
resistant rubber and a layer 18 of a ?brous phenolic
put of the electrical power source 62 is available to be
impressed across the igniter resistance 64 to detonate the
The double-layered washer 14 is clamped in the outer
priming charge, causing explosion of the charge. In the
end portion 12 of the base 10 by a spun ?ange 20 form
majority of instances a suitable switch 66 will be pro
ing part of the case. A three-?ngered contactor 22 is se
vided, in series with the resistance igniter 64, which
cured to the double Washer 14 by a rivet 24. The rivet 24
switch would be arranged to be closed upon impact.
also holds a soldering lug 26 in place, a washer 28 being
By use of this hydraulically controlled switch in the
provided to distribute the pressure and assure good con
particular combination disclosed, it will be assured that
tact between the lug and the rivet, as well as prevent oil
the shell will have advanced sur'?ciently from the muzzle
55 of the ri?e so as to protect the ?ring personnel from
possible injury.
The ?ngers 22 are preferably made of a resilient, good
electrical conductor such as beryllium-copper or Phosphor
Inasmuch as the switch mechanism has three switch
The ?ngers 22 are biased to move toward the
?ngers resiliently engaging the piston stem 30, it will be
axis of the casing and thus resiliently engage the hollow
clear that the possibility of failure to complete the circuit
stem 30 of a piston 32 which is reciprocable within the 60 between the two soldering contacts 22 and 26, due to
casing 10 and which is biased to be held in its inner radial
foreign particles, etc., is extremely unlikely. The fact
position (referring to FIG. 3), by a compression coil
that the switch contacts are provided with a plurality of
spring 34. The stem 30 of the piston 32 is provided with
?ngers angularly spaced from one another, greatly mini
‘an extension 36 which has a cylindrical bore 38 therein.
mizes the chance that the srm'tch might be opened as a
A metering cup 40, having an ori?ce 42 therein, ?ts closely 65 result of impact irrespective of the direction of the inertia
within the bore 38 and is sealed by a suitable gasket 44.
forces or momentum to which it may be subjected.
The piston 32 has a sealing washer 46 which is secured
The ori?ce 42 is provided in the cup 40, as distinguished
in position by a clamping ring 48, the latter being secured
from being formed in the piston 32, so that merely by
by a press ?t over a portion of the piston 32. The seal
substituting cups 40 with di?‘erent sized ori?ces, the de
ing member 46 is preferably made of “Te?on” or other 70 sired delay in the arming of the projectile may be pre
suitable insulating material which is highly resistant to
changes in characteristics due to contact with oil, which
It is particularly important that the seal 46 function
very positively to prevent leakage from one side of the
piston to the other, and it is for this reason that it is
made of a material which, as previously stated, is highly
suited for the purpose. The e?ectiveness of the 'seal '46
out departing from the underlying principles of the in
vention. I therefore desire, ‘by the following claim, to
include within the scope of the invention all such varia
tions and modi?cations by which substantially the results
of my invention may be obtained through the use of sub
is enhanced by the fact that it is of greater outside di
ameter than the internal diameter of the casing 10, and
stantially the same or equivalent means.
I claim:
For use in arming a projectile in response to its rota
as a result its peripheral edge is ?exed toward the direc
tion from which the seal will be subjected to pressure.
tion on its axis, a delay device- adapted for mounting
The seal thus acts in the manner of a cup washer. The
pressure differential on the opposite sides of the seal 10 within the projectile in a position having a substantial
component extending radially from the axis of the pro
operates to increase the eftectiveness of the seal.
jectile comprising a casing having a cylindrical bore re
Furthermore, it will be noted that the thickness of the
Iceiving a hydraulic ?uid of the type having a substantially
metal of which the cup 40 is made is intentionally made
uniform viscosity throughout a substantial range of tem
very small. (The views of the switch in FIGS. 1 and 2
are approximately ?ve times oversize). The reason for 15 perature, a piston reciprocably received in the bore, an
elastic annular washer carried by the piston in ‘sealing
making the cup 40 out of thin sheet metal is to make it
relation with the adjacent inner periphery of the bore
possible more accurately to control the rate of flow of
to prevent appreciable leakage between the piston and .
the hydraulic ?uid throughthe ori?ce 42, because the
casing bore, a spring urging the piston radially inward
?ow rate will be determined substantially solely by the
ori?ce resistance and will not be materially changed by 20 with respect to the longitudinal axis of the projectile, an
element carried by the piston and having a thin, sharp
“pipe” resistance. For example, in one embodiment of
edged measuring ori?ce of shorter length than its diam
thejinvention the cup '40 was made of Phosphor bronze
eter for accurately controlling the rate of ?ow of the
sheet metal having a thickness of approximately .004",
the ori?ce 42 having a diameter‘ of‘approximately .006”.
In the use of the switch mechanism, the compression
spring 34 operates to resist radially outward movement
of the piston 32 and serves the purpose of normally main
’ fluid from one side of the piston to the other as the
taining the piston 32 in the position shown in FIG. 2,
fing axially from the piston, and a plurality of circumfer
so that if, for example, the shell were lying in a position
entially spaced resilient electrical contacts secured to the
piston moves radially outwardly to a predetermined posi
tion incident to gyro-rotary movement of the projectile
as it is propelled from a ri?e, a cylindrical boss extend
such as that the force of gravity, plus possible vibration, 30 casing and biased toward and slidably engaging the outer .
periphery of the boss to establish electrical continuity
would tend to move the piston radially outwardly, this
‘ therewith, the contacts electrically disengaging the boss
possibility would be prevented by the spring 34. More
over, if for some unknown reason the shell fails to
incident ‘to movement of the piston to a predetermined
detonate at impact, the spring 34 will apply a force to
outward position.
References Cited in, the?le of this patent
the piston 32 to cause it to return to a position in which 35
its stem 30 is in electrical contact with the ?ngers 22,
thereby shorting the resistor 64 (FIG. 4) and thereby
rendering the projectile safe against accidental explosion.
While I have shown and described a preferred embodi
ment of my invention, it will be apparent that numerous 40
variations and modi?cations thereof may be made with
I 1,152,433
Murphy _________ __'___'__ Sept. 7, 1915
Needlman ____' _______ __ June 21, 1949
Bleakney et a1 _______ __'.__ July 12, 1955 '
Gascoine et al _________ __ Sept.‘ 25, 1956
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