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Oct 8, 1946-
M. M. SHAPIRO
‘ 2,408,816
PIEZOELECTRIC GAUGE AND METHOD OF MAKING THE SAME
Filed Feb. 10, 1944
241
a/ 0/2
LE
32
48
.
53
INVENTOR.
Mauriae M. Shapiro
BY
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Q
AT'IORNEY.
Patented Oct. 8, 1946
2,408,816
UNlTED STATES PAT ENT-"OFFICE.
' rlnzonnnc'rmo
MAKING THE SAME
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Maurice M. Shapiro, Cabin John, Md.
Application Feb. 10, 1944, Serial No. 521,885 "
7 Claims.
<c1.1i,1_'327_)‘
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(Granted under. the act of’ March 3,1883, as
amended April 30, 1928; 370 0. G. ‘757)
2
The invention relates" to improvements in
piezoelectric gauges and to methods of making
the same, and the primary object of the inven
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out ‘the several views, the letter A generally desig
nates a body of water, B an explosive charge and
C the improved piezoelectric gauge.
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tion is to provide a piezoelectric gauge suitable
While tests may be conducted in anyisu'it'able
for use in the observation and measurement of 5 body'of Water, such as the open sea, in the exam
underwater pressure waves of large amplitude
and extremely short duration, such as produced
by the underwater detonation of large or small
ple illustrated, the water A is containedin" an
explosionv test pond [l0 ‘provided'with an over‘
hanging platform I I for supporting the‘e'quip
ment and personnel. The walls of‘ the test pond
"Another object of the invention is the pro 10 may be provided'with irregularly curved, uneven
vision of a piezoelectric gauge having the small
ly spaced protuberances- l 2 to reduce ‘wave re?ec
charges of high explosives.
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mass and high natural frequency which is neces
sary for the observation and accurate measure
ment of the variation of pressure with time, and
, tion', and a heavy water-tight‘tank l3 maybe
embedded in one side M of the'po'nd with‘ a'wall
l5 exposed to the water. This test pond vforms
themomentum associated with pressure pulses of 15 no part of the present invention and is shown
the character described.
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merely for the purpose of illustration.
A further object of the invention is to provide ‘
a. piezoelectric gauge which is rugged and per
manently waterproof when exposed to the shock
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The explosive charge B may be supported in
the water at any desired depth, as by a bracket [6
and a waterproof ignition cable l1.
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Supported by the platform in spaced relation
20
The invention also aims to provide ajpiezoele'c-v . ,to the bracket I6 is a bracket I8 carrying the
of underwater explosions.
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tric gauge adapted for use in observing the effect
vertical leg of a depending L-shaped bar l9. At
of an underwater pressure wave on a submerged
'tached to the horizontal leg 20 of the bar, as ‘by
plate or'diaphragm having a surface exposed ‘to
a bracket 2|, is, a coaxial cable 22,'preferab_ly)of
25 the ?exible type disclosed and claimed in the co
The invention also‘ is directed to'wardthe pro
pending application for patent of M. M. Shapiro
vision. of an integrally bonded‘ and completely
and B. Stiller Serial, No. 522,288 ?led February
sealedpiezoelectric gauge and methods of making
,In the example shown, the'upper end of the
Other objects and advantages-of the invention 30 cable 22 is connected to suitable instruments dia
the
pressure
the
same.
wave.
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14,1944.
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will become apparent during the course of the
following detailed description, taken in connec
tion with the accompanying drawing, forming a
part of this speci?cation, and in which drawing,
grammatically indicated at 23 and the submerged
end 24 is bent so as to extend forwardly and then
downwardly from the horizontal leg 20.
Figure 1 is a central vertical sectional view of 35
an underwater explosion test pond and diagram
matically illustrating the use of the piezoelectric
gauge in the observation and measurement of
' I
Referring now more particularly to Figures _2
and 3, the piezoelectric gauge C includes a ‘thin
?at hollow cylindrical housing or shell 25 formed
of brass, this metal having been selected mainly
because its modulus of elasticity is close to that
underwater explosion pressures.
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of quartz. The'housing or, shell>25 includes‘ a
Figure ‘2 is a greatly enlarged front elevational 40 shallow pan-like container 26 comprising a ?at
view of the gauge.
wall 21 and a peripheral ?ange 28 provided with
Figure 3 is a central vertical sectional view of
a projectingv brass tube 29 which is silver soldered
the gauge and taken along the line 3—3 of Fig
ure 2.
at 30 to the ?ange to form a water-tight joint.
'
This tube 23 telescopes over the normally ‘sub
Figure 4 is a view partly in elevation and part, 45 merged'end 24 of the coaxialv cable 22 and is sol
ly in section illustrating a step in the method of
dered to the copper sheath 3| of the cable at 32
making ‘the gauge.
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to form a water-tight joint.
Figure 5 is a view partlyin'side elevation and '
‘partly in central vertical section and showing the
‘gauge applied to a plate having an underwater
surface. '
‘In the drawing, which for the purpose of illus
tration shows only a preferred embodiment of
‘the invention, and wherein similar ' reference
characters denote corresponding parts through
’
Telescopically '?tting‘within the ?ange 28 is a
50
disc-like cover 33 comprising a ?at wall'34 and ‘an
inner marginal rim'35. The ‘flat wall 34 forms'a
grounded electrode when thegauge is submerged.
Disposed‘within the container 26 is a copper
sheet 36 constituting an inner electrode and to
which the central conductor 31 of the coaxial
55 Cable is Connected. Positioned between the sheet
2,408,816
3
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36 and the cover wall 34 is a thin circular quartz
crystal 38 of a diameter slightly less than the in
ternal diameter of the rim 35. Positioned be
the soldering, the shellac ?lms 40-43 melt so
that upon cooling, the various parts are ?rmly
bound together to form a solid mass. The C
,
tween the sheet 36 and the container wall 21 is a
clamp 41 is removed only after the metal has
thin dieloctrlczdisc orsheet 33,isuch,as-lmica. The
‘Figure ‘5 illustrates ‘means for adapting the
respective confronting surfaces of the walls 21,
housing or shell 25 of the gauge C to the measure
34, sheets 36, 39 and crystal 38 are bonded by
layers 40-43 of fusible cementitious material,v l 3 \_ment of explosion pressures at the surface 50 of
cooled.
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4
such as shellac. It will be seen that the piezoelec
an underwater diaphragm or plate 5|. The mar
tric transducer assembly thus provided “forms I?‘
with the opposite end walls 21, 34 of the sheila
iginaliedgerof ‘this diaphragm or plate 5| may be
solid body composed entirely of parallel layers
which is inherently capable of withstanding ex
tremely high pressures axially “of 'ithe l'gauge.‘
,openingr?lin .the exposed wall l5 of the tank
l3 illustrated in Figure 1. soldered or otherwise
When the crystal is subjected to a changein pres
sure, the opposite charges ‘developed on ‘its two
faces are transmitted by induction ‘to
electrode and the grounded cover, respectively,
through the layers of shellac.
The‘nontral conductor ' 3.1 :pf‘ the [coaxial "ccable
may be :a Nonilmor No.34-cohmr wireiinsulated
with enamel and :a- double Klayer of 1 glass-?ber M4,,
:and‘ known as ‘?DVE” or yDouble‘rVitrotemEnamvl
clad-wire. Fitted-in the innerlend ofrthe'atube 29
is‘ a Bakelite :bushing 45 through whichrthe lin~
sula’sed central :conductor ?l-extends. The small
space between the insulated conductor 31=and {the
?exible ‘copper ‘sheath ‘3| :is preferably ?lled with
‘mini wax 146 to prevent wibration {of the con
ductoriwdthinthenheath.
‘ The diameter of the cylindricahshell 725~sh0u1d
"be vconsiderably less than“ the length {of the ‘pres
pure-"wane. ,TI'IUSE-IOI‘ underwater explosion ltests
wherein the pressure-drops to one third :of its
peak value in ilms "than seventy microseconds,
‘the ‘shell preferably 1is‘less'than0neHha1f inch in
diameter and‘ its ,rhiclmessLshould belless ,than
one-fourth inch, :so as not :to exceed one-fourth
ot-thelengthof the pressure wave.
bolted ‘in water-tight fashion over a suitable
‘ iintegrally ,ai?xedwto the surface 5!] of the di
aphragrn or plate 5| under investigation is a
short “brass stud 53 adapted for screw threaded
, engagement with a :thin brass nut 54 externally
z'a'f?xed'atoithe ‘container wall 21, as by silver sol
der 55. The diameter of the nut 54 is the same
,as that ‘of the container, and its thickness “is‘not
.less than thelength of'the stand -53 ‘so that the
nut may be threaded into :?rm engagement, with
thesurface ‘50.
>
Variousichanges may-(be ‘made ,in the form-oi
invention and‘method =of -.manuiacture ‘heroin
:shown , and > described. without departing irom- .the
'spirit of the {invention rorilthe scoperoi the .follow
ing claims.
The iinvention- described herein .may her ‘man
20 'ufactured and used by ‘or for ,therGovernment of
the United stateseof ‘America .for-igovernmental
purposes without the paymentlof any royalties
thereon aortherefor.
lclaim:
1. A piezoelectric gauge iorluse intheobsenva
tion and ‘measurement of -.a pressure wave of high
amplitude and short duration, ‘such rasiproduced
‘by the underwater ‘detonation-of a charge‘lof high
explosive, comprising a thinflat hollow cylindri
iBefore-assemblmtm lyariousparts of the gauge 40 cal waterproof shell formed of elastic and elec
are prepared as Yfollows-r The'cqpper sheath ,3!
'cally oonductivemetal, saidshell including spaced
0! theloable atits end 24,~ae well-astheqinner
end-walls and a cylindrical side iwallwprevid‘ed
“surface of the 'brass'tube2laretinned. (The edge
‘with an integral tubular i-outlet, a piezoelectric
of the cover along (the rim~35 is also tinned‘rto
transducer assembly comprising "a plurality of
‘prepare it forisoldering to the container ?ange ,_; .thin fiat :discs :iorming with the endwalls of said
“38. ‘Pure orange shellacicrystalsrare theatedyto
cylindrical ‘shell aésoli'd :body composed entirely
the melting point; then thin coats of shellac are
'ofparallel layers and thereby inhemntlyicapable
‘\abpliedto thelinside'?at surfaces ‘of the cover 33
of withstanding extremely high pressurewaxially
,andi'oantalner P26, aslwell ‘as totbothlsides of ‘the
:of- the gauge, one ‘of :said ‘end "walls constituting
crystal 18 and-micavsheet 33.‘ Before .the shellac 50 a. ‘grounded electrodei‘for said‘ transducer assem
dries, ‘the mica sheet 38 is cemented to. the con
bly'i‘to ‘permit reduction ‘in the mass ‘and'slze of
tainer wall 121 and the crystal .38 is can
"the-gauge, the "mass ‘of the ‘shell ‘being small and
rtrally attached to the insideof the cover wall 34.
the greatest dimension ‘of the “shell ‘being less
The rimM-tonds to insure alignment of the crys
' than'oneahalfiinch.
‘ talwltlrthercenterrof the cover.
2. IA piezoelectric gauge iforiwise in observing
In connecting the conductor ,3‘! :to the inner I‘ utheeffect of a, pressure wave of high amplitude
sheet camper Electrode 36, the coaxial ‘cable .22 is
‘and ‘short duration, such as produced by the un
pushed into-the. brass tube 13 “beyond its normal
derwater detonation of a charge of high explo
position in the ,?nishedgau'ge, .so that “thein
sive, on a plate or‘the like having an underwater
eulatedlwire protrudes from-thecontainer. .The
surface, said gauge comprising a 'thin ?at ‘hol
Bakelite l-bushing '45 is thenslippedlover the
low ‘waterproofshell formed of elastic electrically
glam i?ber vinsulation .44, and .the bored and -.of
conductive metal and provided with a ‘tubular
the conductor is attached to {the electrode 36.
outlet, a piezoelectric transducer assembly com
This may be .-acoompiishod ‘by providing-a mar
prising a plurality of thin flat discs forming with
,ginll slitiin'the electrode andaoompmessing the
the ?at sides of said shell a solid ,body' composed
end of the wire in the slit with .a peenahammer.
entirely .of parallel layers and thereby-inherently
Subsequently, ‘the bushing A5 'iisyinserted in the
capable of withstanding extremelyhigh pressure
tube '2! and the cable ‘is (pulled back until the
axially of thegauge, the mass of thegauge being
electrode 36 lies iconeentrically “over the mica
islmet 33. Next, "the cover with thrGwCTYS‘i?-l at- ' negligible in comparison with the mass ‘of said
plate or the like, ‘and screw-threadedicoupling
‘ Mohedis pressed int-,0 the :contairxer and, while
‘pressure lsmaintainddsbymeans of [a small -0
‘clamp 41. such “as shown in :Figure 4, ‘the tele
scopically ?tting surfaces ‘of the coverand :con
tainer are soft-soldered together at 48. During
means forming a thin solid impulse-transmittim
layerbet-ween- one of the ?at ‘sides of saidprgauge
and said underwater surface forreleasably?xing
the gauge to said plate or the like.
2,408,816
5
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3. In a piezoelectric gauge for use in the ob
said inner electrode and the ?at wall of said con
servation or measurement of a pressure wave of
tainer, a thin ?at piezoelectric crystal disposed
high amplitude and short duration, such as pro
within the container between said electrodes, the
duced by the underwater detonation of a charge
peripheries of said crystal and said inner electrode
of high explosive, a thin ?at hollow housing L1 being spaced inwardly of said rim and ?ange re
formed of elastic electrically conductive metal,
spectively, thin layers of a fusible adhesive be
said housing including a shallow pan-like con
tween the respective confronting surfaces of said
tainer and a disc-like cover, said container com
?at walls, dielectric sheet, inner electrode and
prising a ?at wall, a peripheral ?ange and a
crystal, a conductor extending through said tubu
tubular outlet integral with said ?ange, said cover '
lar outlet and connected to said inner electrode,
comprising a ?at wall and an inside marginal rim
and a solder joint sealing the telescopically ?tting
telescopically ?tting within said ?ange, a dielec
surfaces of said container and cover against the
tric sheet adjacent one of said ?at walls, a piezo
ingress of water or moisture, with said crystal,
electric crystal adjacent the other of said ?at
inner electrode, dielectric sheet and adhesive
walls, a sheet metal electrode between said crystal
layers in tightly clamped and adhesively bonded
and said dielectric sheet, a conductor extending
relation between said ?at walls.
through said outlet and connected to said elec
6. In a piezoelectric gauge for use in the ob‘
trode, and means sealing the telescopically ?tting
servation or measurement of a pressure wave of
surfaces of said container and cover with said di
high amplitude and short duration, such as pro
electric sheet, electrode and crystal in tightly
duced by the underwater detonation of a charge
clamped relation between said ?at walls.
of high explosive, a thin ?at hollow water-tight
4. In a piezoelectric gauge for use in the ob
shell ‘formed of elastic electrically conductive
servation or measurement of a pressure wave of
high amplitude and short duration, such as pro
duced by the underwater detonation of a charge
of high explosive, a thin ?at hollow housing
formed of elastic electrically conductive metal,
said housing including a shallow pan-like con
tainer and a disc-like cover, said container com
prising a ?at wall, a peripheral ?ange and a tubu- ;
lar outlet integral with said ?ange, said cover
comprising a ?at wall and an inside marginal rim
telescopically ?tting within said ?ange, the flat
wall of said cover constituting a grounded elec
_trode, an inner sheet metal electrode disposed
within the container, a dielectric sheet between
said inner electrode and the ?at wall of said con
tainer, a thin ?at piezoelectric crystal disposed
within the container between said electrodes, the
periphery of said crystal being spaced inwardly
of said rim, thin adhesive layers between the
respective confronting surfaces of said ?at walls,
dielectric sheet, inner electrode and crystal, a
conductor extending through said tubular outlet
and connected to said inner electrode, and means
sealing the telescopically ?tting surfaces of said
container and cover with said crystal, inner elec
trode, dielectric sheet and adhesive layers in
tightly clamped relation between said ?at walls
to form an integral substantially solid laminated
body.
5. In a piezoelectric gauge for use in the ob
metal, said shell including parallel sidewalls and
a peripheral wall and being provided with a
tubular outlet integral with said peripheral wall,
one of said parallel sidewalls constituting a
grounded electrode, an inner sheet metal elec
trode disposed within the shell, a dielectric sheet
between said inner electrode and the other of said
parallel sidewalls, a thin ?at piezoelectric crystal
disposed within the shell between said electrodes,
the peripheries of said crystal and said inner
electrode being spaced inwardly of the peripheral
wall of the shell, thin adhesive layers bonding the
respective confronting surfaces of said parallel
sidewalls, dielectric sheet, inner electrode and
crystal so as to form an integral laminated body
substantially devoid of pockets between said re
spective confronting surfaces, a conductor extend
ing through said tubular outlet and connected to
said inner electrode, and means for insulating said
conductor therefrom.
7. The method of assembling a piezoelectric
gauge including a metal container, a plurality of
-., .thin ?at elements ?tting in the container and a
telescopically ?tting metal cover, to form an in
tegral waterproof unit, said method comprising
applying a fusible cement coating to at least one
of each pair of confronting surfaces of said ele
ments, container and cover to hold said elements
in a predetermined preliminarily assembled rela
high amplitude and short duration, such as pro
tionship, disposing said cover in telescopically
?tted relation to the container with said prelim
inarily assembled elements in the container,
duced by the underweater detonation of a charge ,
pressing said cover and container together so as
servation or measurement of a pressure wave of
of high explosive, a thin ?at hollow housing
to tightly hold said elements in predetermined
formed of elastic electrically conductive metal,
position therebetween, soldering the telescopically
said housing including a shallow pan-like con
?tting surfaces of said container and cover with
tainer and a disc-like cover, said container com—
prising a flat Wall, ‘a peripheral ?ange and a tubu
lar outlet integral with said ?ange, said cover
comprising a vflat wall and an inside marginal rim
said fusibly cemented elements clamped therebeé
telescopically ?tting within said ?ange, the ?at
wall of said cover constituting a grounded elec
trode, an inner sheet metal electrode disposed
within the container, a dielectric sheet between
tween so as to remain in predetermined relation
ship upon fusing of said coatings as a result of
the soldering operation, and cooling said con
tainer to a temperature below the fusing tem
perature of said cement before removing the pres
sure on the container and cover.
MAURICE M. SHAPIRO.
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