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Патент USA US3075180

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Jan. 22, 1963
R. 1-. SOREL
3,075,170
HYDROPHONE WITH FRUSTO-CONICAL HOLLOW CARBGN ELEMENTS
Filed June 4, 195B
5%
35’
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25
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177702”: “AS
United States atent
C6
2
1
3,0751%
HYDROPHQNE WITH FRUSTG-QIGNICAL
HQLLO‘W CAREsEN ELEMENTd
Raymond T. Sci-cl, River Road, RED. 2, Mystic, (joint.
Filed .iune 4, 1958, Ser. No. 739,951
1 Claim. (Cl. 34tl-—13)
(Granted under Title 35, US. Code (E52), sec. 266)
Patented Jan. 22, 1963
are super-posed until the larger base ends thereof cover
the contiguous base of the disk 23.
Another disk 28, similar to the disk 23‘ but slightly
smaller in diameter, abuts against and is coextensive
5 with the ‘free ends of the members 26 and 27. A frusto
conical thin rubber iboot 29, which serves as a sound trans
parent cover, ?ts snugly over the exterior of the group
of elements 26 and 2'7, with one end encircling and
snugly ?tting the periphery of the disk 23‘ and the other
The invention ‘described herein may be manufactured
and used by or for the Government of the United States 10 end encircling and snugly ?tting the periphery of the
smaller disk 28. A suitable adjustable clamp 36 extends
of America for governmental purposes without the pay—
around the periphery of the disk 28, over the end of the
ment of any royalties thereon or therefor.
boot 29, so as to clamp the end of the boot tightly to the
This invention relates to hydrophones and particularly
periphery of the disk 28 and provide an impermeable
to carbon hydrophones. Presently used hydrophones
commonly employ magnetostrictive or piezo-electric ele 15 seal therewith and to hold the disk 28 against the con
tiguous ends of the elements 26 and 27.
A water-promc molded rubber boot 31 is secured
against the other end face of the disk 23 by its ?anges
32 which extend in telescopic relation over the periphery
increases the complexity and cost of the devices and re
duces their reliability. In addition the characteristics of 20 of the disk 23 and the adjacent end of the boot 29‘, and
another adjustable clamp 33 surrounds the flange 32 and
the elements make them unsuitable at very low fre
when. this clamp is tightened, it provides an impervious
quencies.
seal between the boots 29‘ and 31 and the periphery of
An object of this invention is to provide an improved
the disk 23. A pair of insulate-d wires 34 and 35 are
carbon hydrophone, with which the overall resistance
of the device can ‘be easily and inexpensively changed; 25 molded in the stem 36 of the boot 31 so as. to extend to
the inner face of the boot 31, where one wire 34- is se
with which the sensitivity and impedance remain con
cured to the integral metal stem 25 of the inertia load
stant over ‘a wide frequency range, especially at low fre
ing weight 24», and the other wire 35 passes near the
quencies; which will respond to frequencies having periods
periphery of the head of the boot and there emerges and
of several seconds or even minutes as well as to the higher
passes through a small oblique passage 37 in the disk 23
frequencies to which hydro-phones should be responsive;
where the wire is electrically secured to the outer-most
which will itself be an ampli?er capable of substantial
frusto-conical metallic member 27.
power gains; which is directional in its responses; which
ments which provide small voltages that are ampli?ed
until they can perform useful functions. A disadvantage
of such hydrophones is that the need for ampli?cation
has minimum of self noise; which has good discrimina
tion in isotropic noise; which has improved mechanical
These spacer members 2.7 which are between the mem
bers 26 have their face areas which abut members as of
considerably less areas than the face areas of the carbon
impedance match to water; which has ‘a relatively high
sensitivity; which is useful for acoustic mines in that
members 26 against which they abut except the outer
it can be made to respond to both acoustic and pressure
most spacer member which has the same face area as the
signatures; with which the electrical impedance is con
stant with ‘frequency; with which the impedance is prac
two disks 23 and 2%, with the boots 29 and 31, form an
tically purely resistive; with which the high output re
impervious enclosure in which the carbon frusto-conical
duces the number of stages of electronic ampli?cation
necessary and makes electronic ampli?cation unneces
waves impinging against the sound transparent boot 29
sary in some cases; which has simple and modest power
on the side of this housing will cause the outermost frusto
adjacent carbon member against which it abuts. The
elements are housed in face to face relation, and sound
conical carbon member 26 to move against the next ad
requirements; and which will be relatively simple, com
jacent one, and progressively on to the innermost one,
pact, durable, practical and inexpensive in construction.
thus varying the resistance between the frustum shaped
Other objects and advantages will be apparent from
carbon elements and the spacers from the outermost
tie following description of the invention, and the novel
Y rustum to the innermost one, as the sound waves vary.
features will be particularly pointed out hereinafter in
This hydrophone is thus also directional in that it is re
connection with the appended claims.
50 sponsive to sound waves striking the boot 29 in a direction
The drawing is a sectional elevation of hydrophone
crosswise of the common axis of the elements 26 and 27.
constructed in ‘accordance with the invention and illustrat
A hydrophone which is trying to discriminate between
ing an embodiment thereof.
a weak distant signal and very close noise sources has an
In the embodiment of the invention illustrated, the
hydrophone includes a disk 23 of non-conducting ma 55 advantage if the close sources do not a?fect the hydrophone
materially. If the local noise ?eld is large enough, it
terial such as ?ber-glass or formica, which is electrically
may appear to the hydrophone that the noise arrives si
non-conducting, rigid, and capable of holding its rigid
multaneously from all directions. The carbon disk hy~
ity under stress. An inertia loading weight 24 is dis
drophone or the hydrophone using the carbon frusto-coni
posed against one face of the disk 23 and detachably
secured thereto by having a reduced stem on the weight 60 cal elements, changes the resistance for signals coming
from one direction while pressures from signals arriving
24 threaded into ‘an aperature in the disk 23. The load
simultaneously from other directions are mechanically
ing weight is tapered toward its free end, and circular
in cross section so as to be frusto conical in shape. This
inertia loading weight is of metal, and telescoped snugly
upon it and upon each other are a plurality of frusto coni
cal elements or sleeves 2a of suitable carbon material.
Disposed between the successive elements 26 are frusto
conical thin sleeves ‘27 of metal which separate the ad
jacent faces of the frusto conical elements and are pro
cancelled out.
Conventional piezoelectric or magneto
strictive units produce outputs regardless of the mode
that the unit is excited. These units usually rely on the
sensitivity of a particular mode to give directional char
acteristics, or an array of units is used, with proper phas
ing, to give directional characteristics.
For the cone frustum construction of the carbon ele
ments, the sensitivity pattern for this con?guration is
vided with apertures 27:: from face to face except for 70 doughnut shaped, and therefore this con?guration is sen
the outermost sleeve 27’ which does not have any aper
sitive to sounds in all directions except those parallel to
tures. These successive frustums of cones 26 and 27
the axis of the cone.
3,075,170
21
The inertia of the loading weight causes the sides of
the carbon cone frustums to move when a sound wave
comes from some direction at right angles to the cones.
order to ex lain the nature of the invention, may be made
by those skilled in the art within the principle and scope
of the invention as expressed in the appended claim.
I claim:
A carbon hydrophone for inclusion in a hydrophone
utilization circuit comprising an‘ electrically non-conduct
ing rigid disk, a metallic frusto-conical inertial member de
The sound pressure coming from one side causes the sides
of the cone at that side of the axis to compress and reduce
the resistance, and at the same time the sides of the
cones on the other side of the axis will be moved apart
tachably affixed centrally of said disk with its tapered tree
so as to reduce the resistance, but unless the sound pres
end extending away from said disk, a group of substantial
sure travels through the cones instantaneously, which is
a physical impossibility, the reduction in resistance on 10 ly rigid hollow frusto-conical carbon elements with sub
stantially broad faces as compared to their thickness ar
the said other side of the axis will not arrive soon enough
ranged coaxially in telescoping relation on said member,
to subtract from the increase in pressure on the sides ?rst
‘thin frusto-conical metallic sleeves interposed in abutting
engaged by the sound waves. The low frequency re
face to face ‘relation between adjacent elements, said
sponse of the cone frustum will be limited to a frequency
sleeves having smaller face areas than those of the ele
which is so low that the change in acoustic pressure
ment against which they abut, a metallic outer frusto
coincides with the speed of sound through the cones.
conical sleeve abutting the outermost element and of a
Frustums are used instead of cylinders to make a snug
face area approximately equal thereto, said sleeves and
?t between elements without the need for maintaining pre
carbon elements covering substantially all of the ‘face of
cise dimensions. The illustrated embodiment of this in
said disk against which the ends of said elements and
vention has an improved mechanical impedance match to
the water. Hydrophones according to this invention
have wide uses including the use in fathorneters, sonar de
vices, acoustic mines and underwater telephones. This
type of hydrophone is particularly useful in connection
sleeves abut, a second electrically non-conducting disk
abutting and covering substantially all the free ends of said
elements and sleeves, a frusto-conical boot of sound trans
Mine sweeping gear can explode
parent and water impervious material extending between
said disk and said second disk, sealed thereto in abutting
most acoustic mines by towing a noisemaker on a para
vane. An acoustic mine with a carbon element hydro
relation ‘with said outer sleeve, a water impervious end
boot extending across and covering the face of said disk
phone in accordance with this invention can be made
sweep proof. Because of the very low frequency re-’
spouse of this new type of carbon element hydrophone,
it can be made to close a circuit alerting it to noise sig
opposite said elements and sealed thereto, a pair of wires
extending through said end .boot, sealed therein, one of
said wires attached to said member and the other passing
through said disk and attached to said outer sleeve where
by said hydrophone is water impervious and compression
with acoustic mines.
nals, only after the very low frequency pressure signature
(pressure variation with respect to time or frequency) of
a large ship is sensed. In other words, the hydrophone
would refuse to listen to noise unless a large ship came
within range, where the movement of the water caused
by the displacement of the hull caused the mine ‘to be
come alerted. While such mines are already in existence,‘
they are more complicated than those using a carbon
element hydrophone in accordance with this invention,
because they usually have a separate pressure signature
(pressure variation with respect to time or frequency)
sensing element, and the hydrophone output has to be
ampli?ed to actuate the mine. Hydrophones made in ac
cordance with this invention are easily disassembled by
removing the boot 29. It will be understood that vari
ous changes in the details, materials and arrangements of
parts which have been herein described and illustrated in
al waves impinging on said frusto-conical boot will be
transmitted to said elements.
References Cited in the tile of this patent
UNITED STATES PATENTS
380,925
1,544,786
1,584,613
1,829,489
2,405,226
2,405,604
Phelps ______________ __ Apr. 10,
Walker ______________ __ July 7,
Cornstock et al. ______ __ May 111,
Mularkey ____________ __ Oct. 27,
Mason ______________ __ Aug. 6,
Pope ________________ __ Aug. 13,
1888
1925
1926
1931
1946
1946
2,515,867
Fuller ___' __________ __'_ July 18, 1950
2,813,181
Seavey _c_ ____________ __ Nov. 12, 1957
2,830,202
Feinstein ____________ __ Apr. 8, 1958
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