Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a fle~bl- hou-ing for
use ~n protecting one or more microwave transmisæion
lines in a pressurised environment and in particular, a
hydrostatically pressurised environment.
The invention originates from a requirement for a
microwave transmission line to operate within a
submarine mast environment. Modern submarine mast
design dictates the placement of eleotronic equipment
in an e~ectronics pod at the mast head connected by
lo microwave transmission line~ to processing equipment in
the hull. This arrangement creates the requirement for
a microwave transmission line capa~le of withstanding a
hydrogtatic pressure of up to 1000 psi ~6.89 ~ 10
Nm 2) and yet able to fle~ through an angle of 180
wlth a bend radius of 150mm when the mast hea~ is
raised.
~n the past various ~wet mast~ techniques have involved
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the ruggedising o coaxial mi,crowave cableæ so as to
limit to an acceptable level the amount of hydrostatic ~
pressure felt by the cable. Often under such pressure ~ ~i
conditions it i8 the dielectric within the coa~ial ;` ~i~
cable that absorbs the bulk of the compressive forces ;~
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altering the microwave characteristiCs of the cable.
~he u8e Of a more ri~id dielectric material to overcome
the problem of compression under hydrostatic pressure
has an adver~e effect on cable performance, urthermore
this technique limits the types of cable whiCh can be
used, their number and their application and
consequently has a detrimental effect on the
performance of the system as a whole.
The above technique also requires the use of some form
of cable management system to ensure that the cableæ
hang and remain in a defined position undes the ~arious
dynamic conditions of the submarine. Each microwave
transmission line linking the electronics pod at the
mast head with the processing e~uipment in the hull
will contain a flexure through 180, the point of
fle~ure being determined by the relative heights of tbe
terminations of the transmission line and the point of
flexure will thw change as the mast is raised. The
cable management system not only has to allow for the
smooth change in position of the point of flexure but
also has to ensure that the transmission lines are
; unaffected by the angle of dive of the submarine, which
may be of the order of ~ 10, or the angle of tilt of
the submarine caused by a surface swell and possibly of
the order of 1 30,
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The present invention is oncerned with the provision
of a barrier between a pressurised environment and a
microwave transmission line thus enabling the use of
cables selected ~or their microwave characteri8tics
rather than their ability to withstand hydro8tatic
pressure. This is obviously beneficial to the ~
performance of the system while the barrier, in the ~-
form of a fle~ible housing, enables the transmi8æion ~ ~
line to withstand far greater hydrostatic pre88ure8 ~ :
than hereto~or. The design of the present invention
also eliminates the need for a cable management system
thus simplifying the mast design. - .
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According to a first aspect of the present in~ention ~
there is provided a fle~ible housing for u~e in . ~; .
protecting a microwave transmission line in a ~ ~
pre8suri8ed environment comprising a conduit contained ~ *~,
within encasing means, the conduit being constructed of
a plurality of segments,` each conduit` segment having an
opening therethrough defining a through axis, the ~ ;
segments being arranged in series and caused to abut
adjacent segments in such a way that the opening
through each segment is in communication with the
openings through each of the said adjacent segments 80 ~ S
as to provide a passage to contain a microwave ~ ~,,"'!
transmission line, each segment being flexibly linked -~
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to its adjacent segments by a pair of fleslble
ligaments running throughout the length of the conduit
and passing in turn through each conduit segment in
dedicated channels displaced from the opening
therethrough.
According to a second aspect of the present invention
there is provided a flexible housing for use in
protecting a microwave transmission line in a
pressurised environment comprising a conduit contained
within encasing means, the conduit being constructed of
a plurality of segments, each conduit segment having an
opening therethrough defining a through a~is, the
segments being arranged in series and caused to abut
adjacent segments in such a way that the opening
through each segment is in communication with the
openings through each of the said adjacent segments so
as to provide a passage to contain a microwave
transmission line, each segment being flesibly linked
to its adjacent segments by coupling means and some or
all of the conduit segments being provided with a first
set of spaced-apart butting surfaces orientated
generally perpendicular to the through asis, pairs of
said first butting surfaces being caused to abut each
other in regions of the conduit spaced from a flesure
thereby urging the said regions to maintain a straight
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disposition. ~
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Although the present invention originated from a ~-
consideration of the problems of microwave transmission ~ -
in submarine mast design, protective flesible housing~
5 embodying the invention are egually suited to other
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applications wherein a microwave connection is reguired --
within an environment that would be unsuita~le for an
otherwise unprotected transmission line. Similarly, ; `
even though the prior art has been discussed with
10reference to the use of coasial cables it is understood
that this is in no way intended to limit the scope of ~ ~
the invention, the present invention being equally ~ -
applicable to other microwave transmission means.
Flexlble housings embodying the invention will now be - ~`
particularly described by way of e~ample, with
reference to the accompanying drawings in which~
Figure l is a cross-sectional view of part of one of
the flexible housings;
F~gure 2 is an exploded perspective view of two ~-
adjacent conduit segments in the housing of Figure l; ~ `
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Figure 3 is a lateral view of one of the conduit
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segments of Fig. 2; ~ ~
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Figure 4 i8 an axial view of the conduit segment of -~
Figure 3;
Figure 5 is a lateral view of another of the conduit
segments of Figure 2;
Figure 6 is an axial view of the conduit segment of .
Figure 5;
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Figure 7 is a cross-sectional view of part of another
of the flexible housings;
Figure 8 is a top plan view of an insert shown in
Figure 7; ~ .i,
Figure 9 is a side elevational view of the insert shown ~ ~.
in Flgure 7; f,';~i'`.'',"~' i,
Figure 10 is a detailed cross-sectional view of the
lns rt shown in Figure 7, taken along line 10-10 of Figure
Figure 11 is a cross-sectional view of part of a
further one of the flexible housings.
The flexible housing shown in Figure 1 comprises a
: 20 conduit 10 and encasing means 12, in turn comprising an
inner sleeve 14 and a protective outer jacket 16. The
conduit 10 is constructed of a plurality of conduit segments ,~
: 18, the number o$ segments being determined by the length o$ `~.-
housing required, and in the embodiment '~
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shown the segments are of one of two configurations.
The first confiquration of conduit segment lBa i8 of
biconcave cross-section while the second configuration
of conduit segment 18b, is of circular cross-section.
~he segments 18 are arranged in series, the two
conigurations of conduit segment, 18a and 18b,
alternating along the length of the conduit 10, and
caused to abut adjacent segments. ~he cross-sectional ;
radius of the second configuration of conduit segment
18b iæ of substantially similar value to the radius of
curvature of the first configuration 18a so that the
convex arcuate surfaces 20 and 22 of the second
coniguration of conduit segment 18b are received by
the concave arcuate surfaces 24 and 26 of the adjacent
8egments of the first configuration 18a. ~ -i
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Each conduit 8egment 18, irrespective of configuration,
has an opening 28 therethrough, the segments being
arranged in series so as to abut adjacent segments in
such a way that the opening 28 through each segment 18
is in communication with the openings 28 through each
o~ the said adjacent segments. In this way a passage
is provided along the length of the conduit 10 to
contain a microwave transmission line, the microwave
transmission line being of any suitable form.
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In a preferred embodiment, the opening 28 through each
6egment 18 iS flared at oppoSite ends so as to create
larger entrances with which the openings of adjacent
segments may be in communication. AS a result the
degree of flexure in the conduit may be increased, that
is the bend radius may be decr.eased, whilst maintaining
the openings through ad3acent segments in communication
with each other and the passage created thereby of
sufficient minimum cross-section to contain a microwave
transmission line. r~
The conduit segments of biconcave cross-section 18a are
provided with a first set of oppositely-facing,
spaced-apart butting surfaces 38 disposed at edge~ of
the segment to one side of the opening 28, the butting
surfaces 38 being generally perpendicular to the
through axis 36 of the said opening. As may be see,n
rom Figure 1, when the two configurations of conduit
segments, 18a and 18b, are arranged in series
alternating along the length of the conduit 10, pairs
of oppositely-facing butting surfaces 38 are brought
into close proximity with one another, one butting
surface of the pair being provided by each of the two
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segments o biconcave cross-section 18a disposed either ; ; ;
side of a segment of circular cross-section 18b.
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Each conduit segment i8 is flexibly linked to its ~ ~;
adjacent segments by coupling means. As may be most
clearly seen in Figure 2, the coupling means comprise a
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pair of flexible ligaments 34 running throughout the
length of the conduit 10 and passing in turn through ~ -
each segment 18 in dedicated channels 35 displaced from
the opening 28 therethrough. The flexible ligaments 34
may be terminated by variable tensioning means ~not
shown) at the terminations of the conduit 10, and
preferably tensioned to approximately 133 Newtons (30 ,;;-
lbs force).
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In the flexible housing shown in Figure 1 and in the
conduit segments shown in Figures 3 to 6, the flesible
ligaments 34 are shown passihg through each c~nduit
segment 18 at a distance away from the through axis 36
o the opening and nearer the first set of butting
8urfaces 38. ~hat is, the plane defined by the passage
of the two flexible ligaments 34 through a conduit
segment 18 does not contain the through asis 36 of the
opening 28 of that segment so that the tension in the
flexible ligaments acts at a distance from the through
axis 36. The effect of a force acting off centre of
the natural axis of the segments is, in the regions of
the conduit 10 away from the point of flexure, to cause
~5 the pairs of butting surfaces 38 to abut each other.
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Since the butting surfaces are generally perpendicular ~ ''4
to the through a~is 36 this results in these règions i
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being urged to maintain a strai~ht disposition without
recourse to a more slaborate conduit management system ~-~
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analogous to the cable management systems of the prior
art. Within the region of the point of flesure the
butting surfaces 38 open out to allow a smoothly
curving flesure through 180, the position of the
point of flexure being dependent upon the relative
heights of the terminations of the conduit.
The minimum inside bend radius of the flexure i8
determined by the configuration of a second set of
oppositely-facing, spaced-apart butting surfaces 39
provided on the conduit segments o biconcave
cross-section 18a. The second set of butting surface8
39 are similarly disposed at edges of the æegment but
on opposite siaes of the opening 28 to those of the
first set 38. However, unlike the first set, the
second set of butting surfaces 39 are not spaced so far
apart and are inclined to a plane perpendicular to the
through axis 36. When the two conigurations o
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conduit segments, 18a and 18b, are arranged in series
alternating along the length of the conduit 10, pairs
of the second butting surfaces 39, li~e those of the
first 38, are brought into close prosimity with one
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another. In the regions of the conduit 10 away from
the point of flesure, pairs of the second butting
surfaces 39 do not abut each other since the surfaces
are not spaced so fa~ apart as the first and so do not
interfere with the straight disposition that the
conduit is urged to maintain as a result of the action
of pairs of the said first ~utting surfaces 38. Within
the region of the point of flexure however, pairs of
these second butting surfaces 39 are urged into contact
with one another until the inclined surfaces abut..each
other preventing further movement of the segments
against each other. Thus the maximum angle at which
one segment of biconcave cross-section 18a may be
disposed relative to a segment-of similar cross-section
located adjacent to an adjacent segment of circular
cross-section 18b is determined by the angle Of
inclination of the surfaces 39 and hence gives rise to
a minimum inside bend radius.
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Owing to the design of the conduit segments la the
flexible housing is only capable of fleYure in one
plane. The housing i8 additionally urged to maintain a
planar disposition by providing the arcuate surface of
one conduit segment with guide surfaces while the
arcuate surface o~ the atjacent conduit segment
abutting thereagainst iB provided with means to
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cooperate with the guide surfaces to prevent relative
lateral movement between the segments. The guide
8urfaces and cooperating means may be of any convenient
de8iqn, for example a ridge on the lateral edges of one
segment received in grooves of the adjacent segment.
In the embodiment shown in Figures 3 to 6 the guide
surfaces are in the orm of a 45 radial abutment 40
while the means cooperating therewith is a 45 radial
chamfer 42. In the embodiment shown the radial
abutment is applied to the segment of biconcave
cross-section and the radial chamfer is applied to the
segment o~ circular cross-section although it is
understood that these features may be applied in the
opposite sense.
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The conduit is enclosed within an inner sleeve 14 of
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preferably shrink-f it material which is in turn
contained within an outer protective jacket 16. The
material of the oùter protective jacket is dependent `
upon the application of the housing and the ~'
characteristics of the environment against which it ~ 8
to offer protection but may typically be of extruded ~`~
polyurethane. The material of the inner sleeve i8
selected to have similar thermal expansion properties `~ `
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to those of the outer protective jacket as well as ;
~5 having a low coefficient of friction and some elastic ;
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propertieæ. ~he inner sleeve 14 prevents the adherence -
of the outer ~acket 16 to the assembled conduit
8egment8 thu8 allowing the movement of the jacket 16
over the conduit segments during f lesure. ~he inner ; ~ -~
sleeve 14 is itself prevented from beinq pinched ~ ~.
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between abutt$ng segments during fle~ure and in
particular between pairs of the first or second set of
butt~ng surfaces 38 or 39 of the segments of biconcave
cross-section 18a, by strips 44, preferably of nylon,
the length of .the conduit placed between the inner
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sleeve 14 and the conduit 10.
In the housing shown in Figure 7, the strips 44 are
replaced by inserts. 46 received within qrooves 48 of
the conduit segments of circular cross-section 18b. ~8
may be ~een from Figures 8-10, each insert 46 compr~ 3es a
base section S0 for reception within one o the said ~.
grooves 48, the base section 50 having æhoulder
~urfaces 52 and 54 continuous respectively with the .~
convex arcuate surfaces 20 and 22 of the conduit ~`
Qegment in which the insert 46 is received, and an
e~ternal port~on 56 havinq inner and outer surfaces 58 .~ .
and 60, the e~ternal portion 56 being connected to the ,',.".",,,~,~r',
base 8ection 50 by means of a connectinq member 62.
In the embodiment shown in Figure 7, each condu~t i~
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segment of circular cross-section 18b is provided with --
two grooves 48 orientated perpendicular to the through
a~is 36 of the conduit, the inserts 46 received thereby
being designated as inner and outer bend radius ~-
inser~s, 46a and 46b, respectively. As may be seen,
the configuration of the inserts is such as to receive ~ -~h
pairs of a first or second set of butting surfaces 38
or 39 within the openings created by respective
shoulder surfaces 52 or 54, the connecting member 62
and the inner surface 58 of eYternal portion 56. Hence
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the conveY arcuate surf aces 20 and 22 of the conduit
segments of circular cross-section 18b may be received
by the concave arcuate surfaces 24 and 26 of the
ad~acent segments of biconcave cross-section 18a as :~
previously described. When the two configurations of
conduit segments, 18a and 18b, are arranged in ~erie8
in this way with the segment configurations alternating -~
along the length of the conduit 10, the external
portions 56 of inserts 46a and 46b overlay a portion of
each of the two adjacent conduit segments of biconcave :
cross-section 18a in the region of pairs of a second or ~ !V
first set of butting surfaces, 39 or 38 respectively, ~ ~J`
preventing the inner sleeve 14 of the conduit encasing
means 12 from being pinched therebetween.
It will be appreciated that in this form of the ~ ~
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housing, the conduit management system operates in a
manner similar to that previously described. The
conduit segments 18 in the regions of the conduit 10
away from the point of flexure are still urged, as
before, to maintain a straight disposition as a result
of the tension in the ligaments 34 acting at a distance
from the through axis 36 of the conduit. In the
housing under consideration, however, pairs of the
first butting surfaces 38 abut the connecting member 62
of the outer bend radius inserts 4 6D, the connecting
member 62 being generally perpendicular to the through
axis 36 of the conduit. As before, within the region
of the point of flexure, the butting surfaces open out
to allow a smoothly curving flesure but not
sufficiently as to be no longer received within the
openings created by the shoulder surfaces 52 or 54, the
connecting member 62 and the inner surface 58 of the
external portion 56 of the insert. The outer surface
60 of the external portion 56 of the insert 46b is
provided with a curved profile so as to optimize the
smoothly curving profile of the conduit 10 in the
region of the flexure and minimize the possibility of
damaging the inner sleeve 14.
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Similarly the provision of inserts 46 in place of the ;: ;
strips 44 does not affect the possibility of
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determining the minimum inside bend radius of the
flexure. AS has been previously described, the second
butting surfaces 39 provided on the conduit segments of -
biconcave cross-section 18a are not spaced as far.~apart
as those of the first so that in the regions of the ` -`-
conduit 10 away from the flexure, like that shown in -;-
Figure 7, pairs of the second butting surfaces 39 do
not abut the connecting member 62 of the inner bend
radius inserts 46a. Within the region of the point of ~~;
flesure however, pairs of these second butting surfaces ~x
39 are urged toward the connecting member 62 until they
abut thereagainst preventing further movement of the ~ ;
segments against each other, this movement being ; ~
facilitated by the fact that the esternal portlon 56 of i:
the inner bend radius inserts 46a are capable of
undergoing flexion. Thus, as before, the angle at -
which one segment of biconcave cross-section 18a may be
disposed relative to a segment of similar croæs-section
and located adjacent an adjacent segment o circular
cross-section 18b is limited giving rise to a minimum
inside bend radius of the flexure. In this particular
embodiment however, that limitation is determined by `i `i
the dimensions of the connecting member 62 of the inner -~ c
bend radius insert 46a that is received within a groove
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48 of the said adjacent segment of circular cross
section.
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Furthermore, it will be appreciated by thoss sklll~d in
the art that the inner and outer bend inserts 46a and
46b, may be oS identical configuration ~or ease Of
manu~acture or may be of di~fering configuration so as
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to optimize their slightly di~ering functions, in
particular the connecting member 62 of the inner bend
radius inserts 46a may be provided with surfaces
inclined to a plane perpendicular to the through axis
36 so as to mate with the inclined surfaces of the
o second butting surfaces 39. Alternatively, the inserts
46 and the segment of circular cross-section 18b by
which they are received may be made as one piece thus
dispensing with an assembly operation during the
production stage of the conduit.
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In ths housing, shown in Figure l1,the plurality of
segment6 that comprise the condu~t 10 are of a single
configuration 118. As in the first embodiment
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described above, the segments 118 are provided with an '~'~'!"''.,~'"'
opening 28 therethrough and arranged in series and ;
; ~ 20 caused to abut adjacent segments in such a way that the :
opening 28 through each segment 118 is in communication ~
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with the openings through each of the said ad~acent
segments. In contrast to the previous embodiment
however, each segment 118 is provided with a conve~
arcuate surface 30 and a concave arcuate sur~ace 32,
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each arcuate surface being of siubstantially similar
radius of curvature so that the conve~ arcuate surface
30 of one segment may be received by the concave `~
arcuate surface 32 of an adjacent segment.
It will be appreciated by those skillsd in the art that
the features such as the provision of fleYible
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ligaments and butting surfaces that comprise the
conduit management system, the provision of .guide
surfaces and means cooperating therewith preventing
relative lateral movement between the conduit segments
and the provision of overlaying strips, preferably of
nylon, to prevent the inner sleeve of the encasing
means from being pinched between abutting segmenits
during flexure all of which have been earlier
de~cribed, are applicable in an analogousi manner to the
embodiment shown in Figure 9.
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