Note: Descriptions are shown in the official language in which they were submitted.
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1 FIELD OF THE INVENTION
The present invention relates to a Elexible
tube in combination witn a non~structurally supporting
conductor or conductors of electromagnetic energy.
DESCRIPTION ~F THE PRIOR ART
AND BACKGROUND CONSIDERATIONS
A prevalent tube or hose construction comprises
one or more elongated strips which are helically wound
about an a~is and bonded at adjacent convolutions into
tubular form. A number of such hoses incorporate
electrical conductors and, many times, the conductors
are extruded or otherwise formed into the elongated
strip or strips prior to the time when the strip is
convoluted helically into tubular shape.
Such convoluting creates great tensile and
compressive forces which are exerted upon the conductor.
As a consequence, the conductor may be stretched
beyond its elastic limit and broken or, alternatively,
the conductor is compressed tending to bunch it up. In
addition, when the hose is bent, various portions of
the hose are either compressed, or placed in tensionO
This further tension and compression may create further
stresses on, or fatigue, the conductor and thus cause
it to break.
In order to prevent breakage of the conduc-
tors, it is conventional to utilize a wire which is
sufficiently massive to withstand breakage under such
tension and compression. The massiveness of the wire
can force the plastic of the hose to yield instead of
the wire. In similar or other cases, stranded wire
has been specified and single wire prohibited because
stranded wire, having a twist to it, will yield and
tend to untwist and lengthen upon application of tensile
loads thereon to avoid breaking.
~L2~7~2
1 All such solutions have a common disadvantage
in that they require a minimum wire gauge sufficient to
resist or compensate for such forces. Thus, the gauge
or number of wires is generally greater than that
required by the power requirements. As a result, the
amount o~ material and the cost of the hose is increased.
Also, its flexibility is decreased.
SUMMARY OF THE INVENTION
,
The present invention meets or overcomes the
above-noted problems by utilizing an enclosure for the
conductor or conductors which is sufficiently large as
to provide a space for movement of the conductor or
conductors upon exertion of any tensile or compressive
forces on or by the tube.
14 Several advantages are derived from such
construction. Because the conductors are placed in an
environment which permits them a relatively free move-
ment beyond that which defines a captive space in the
hose, any tensile and compressive forces exerted on or
by the hose are not deleteriously exerted on the con-
ductors. As a consequence, the conductor may be sized
or otherwise constructed to that which is expressly
suited to or required by power or transmisson needs
without any compensation in its size to increase its
physical strength. Thus, the smallest gauge wire or
size of conductor may be used. Further, a single
rather than a stranded wire may be used. In this
respect, while stranded wires are more flexible than
comparable current-carrying solid wires, they are also
considerably more expensive which, in a cost~conscious
environment, is usually critical to making a sale.
Such a construction also improves upon and enables the
full use of the concepts disclosed in U.S. Pat. No.
4,310,94 60
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1 other aims and advantages, as well as a more
complete understanding of the present invention, will
appear from the following explanation of exemplary
embodiments and the accompanying drawings thereof.
BRIEF DESCRIPTION OF TRE DRAWINGS
FIG~ 1 illustrates one embodiment of the
combination of a hose and conductors of electromagnetic
energy formed in accordance with the teachings of the
present invention;
FIGS. 2a and 2b, respectively, illustrate
equal lengths of unconvoluted and bent strips with
equal lengths of wires therein to illustrate contracting
and expanding movement o~ the conductors with respect
to the strip when it is bent;
FIG. 3 depicts a cross-section of the FIG. 1
embodiment of the strip and its contained conductor to
compensate for such contraction and expansion of the
conductor, in which the unconvoluted strip is represented
only by full lines and the convoluted and bonded strip
or strips are represented by both full and dashed lines;
and
FIG. 4 shows a further embodiment of the
present invention illustrated as a hose formed from
two strips configur~d differently from that illustrated
in FIG. 1, with a conductor carried by each strip.
DESCRIPTION OF T~E PREFERRED EMBODIMENTS
As shown in FIG. 1, a hose 10 comprises a
pair of adjacently placed strips 12 and 14 which are
helically wound about the hose axis into tubular form.
It is to be understood that one, two or more than two
strips may be used. Each strip includes a central
generally U-shaped segment 16 having a pair of radially
extending legs 18 and 20 and a connecting crown 22.
pair of terminal legs 24 and 26 are joined respectively
to radially extending legs 20 and 18 and extend in
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1 opposite axial directions~ When the strips are convoluted
or helically wound into tubular form, tu~ular leg 24 of
one strip overlaps terminal leg 26 of the adjacent
strip at the adjoining convolution to form overlapping
surfaces 28 and 30 which are bonded to one another.
Such a construction resists deformation forces exerted
radially and/or axially upon the hoseO In general,
legs 18 and 20 resist radially-exerted crushing forces
on the hose, while the double thickness of legs 24 and
26 resist axially-exerted hose crushing forces by
providing greater rigidity than segments 16.
An enclosure 32 is formed on leg 20 and
defines a pocket 34 whose radial length, that is its
length perpendicular to the hose axis, is substantially
greater than its axial thickness. One or more conductors
36 and 36a, respectively in strips 12 and 14, for
carrying electromagnetic energy are loosely placed in
their respective enclosures 32 for easy movement between
the radial extremes of pocket 34~ If desired, more
than one conductor may be placed within an enclosure
32 As shown in FIG. 1, enclosure 32 is placed inter-
mediate legs 18 and 20 within the inside of U-shaped
segment 16. In addition, an exterior surface 38 of
enclosure 3~ is disposed to lie ~oplanar with a surface
~0 of terminal leg 26. It is to be understood, however,
that enclosure 32 may be placed on leg 18 rather than
on leg 20.
The radial dimension of pocket 34 is an
important feature of the present invention, regardless
of the time when conductor 36 or 36a is placed within
pocket 34 of strip 12 or 14, that is, either when it is
extruded or thereafter, and especially prior to the
strip's helical convolution into a hose. ~eference to
FIGS. 2a and 2b illustrate the reasons which explain this
important feature. FIG. 2a illustrates a strip 112 in
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1 its unconvoluted condition and incorporates a pair of
wires 136 and 136' which are placed and slidably held
in position on either side of the strip's center of
mass 142~ A center of mass is defined as that portion
of the strip on an axis which is perpendicular to the
strip's length and about which the strip portion is
neither compressed nor stretched when it is bent. It
need not be at the geometric center of the strip.
The lengths of wires 136 and 136' between their respec-
tive ends 137 and 137' are equal in both FIGS. 2a and
2b. Also, the length of strip 112 between its ends
113 is also equal in both FI~S. 2a and 2b. In FIG. 2a,
ends 137 and 137' respectively of wires 136 and 136'
are shown to e~tend equally from ends 113 of strip 112.
When strip 112 is bent, as illustrated in FIG. 2b, that
strip portion above center of mass 142 is stretched so
that ends 137 of wire 136 are pulled inwardl~ with
respect to strip ends 113, while that strip portion
below center of mass 142 is compressed so that ends
137' of wire 136' are forced further outwardly from
strip ends 113. If ends 137 and 137' of the respective
wires were held fixed with respect to ends 113 of strip
112~ it is apparent that wire 136 would be placed in
great tension and possibly break, while wire 136' would
tend to be bunched up under compression. It is the main
purpose of the present invention to prevent either
tensile or compressive forces to be exerted on the wires~
In addition to the need to compensate for the
problem of shortening or lengthening of the wire when
the wire is not on the center of mass of the strip, it
has also been determined that the center of mass will
move upon helical convolution o~ the strip and bonding
thereof when formed as the hose. This phenomenon is
illustrated in conjunction with FIG. 3, in which the
unconvoluted strip is represented only in full lines
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1 and the convolutsd and bonded strip is repr~sented byboth full and dashed lines. Strip 12 in its unconvoluted
condition has a center of mass which is shown to extend
along dotted line 144. After the strip has been convo-
luted and bonded together in its tubular ~hape, thecenter of mass moves to a position denoted by line
144'. This movement is dependent upon two occurrQnces.
The first is a stretching of the strip in which its
crown 22 may be somewhat stretched and its legs 24 and
26 somewhat compressed. Therefore, the center of mass
will move to the extent that the material of the strip
is stretched and compressed. In addition, when legs
24 and 26 are bonded together, they form a greater
thickness of material along with the bond material.
This bonded construction is, therefore9 thicker and
less subject to yielding upon bending of the hose.
Therefore, these two conditions of stretching and
compression of portions of the strip, as well as thick-
ening of other sections through bonding, causes the
center of mass to move from its original position
depicted by line 144 to its final position as depicted
by line 144'. This distance is denoted by dimension
44. Therefore, the radial dimension of pocket 34
should be at least that of dimension 44 between the
original and final locations of the center of mass.
However, to avoid possible miscalculation, a radial
length 46 of pocket 34 is made greater than dimension
44. In general, such a dimension 46 of pocket 34
incorporates a substantial length of leg 18 or 20 and
preferably is greater than one-half the leg's length,
but not so long which would interfere with the flexure
of the hose at crown 22 and other portions of the
strip.
Referring now to the embodiment shown in FIG.
4, a hose 210 is illustrated as comprising a pair of
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1 strips 212 and 214, although one or three or more
strips may be used, whose configuration presents advan-
tages over those of the embodiment of FIGS. 1 and 3 in
strip and hose shape, manufacture, economy of material,
and resistance to radial crush and deformation, as
will become appreciated hereafter.
Each strip 212 and 214 includes a generally
U-shaped or hook-shaped end segment or cover 216
comprising a pair of radially extending legs 218 and
220 and a crown 222. Segment leg 220 terminates at
one end 224. Other segment leg 218 is connected by
an axially extending base leg 226 with a radially
extending enclosure 232. ~nclosure 232 includes radially
extending sides 232a and 232b which define the sides
of a pocket 234 for housing one or more conductors,
with single conductors 236 and 236a being specifically
depicted in their respective strips 212 and 214. Each
pocket 234 has a radial dimension 246 which is greater
than the movement of the center of mass extending
along a line similar to line 144 or line 144' depicted
in FIG. 3 for the same reasons as those presented
above with respect to FIGS. 2a, 2b and 3. For economy
in the use of material and length of hose, the axial
dimension of pocket 234, and likewise of pocket 34 of
FIGS. 1 and 3, is less than that of its radial dimen-
sion, but this need not be a necessary constraint if,
for example, the number of conductors placed within
the pocket so requires an expanded axial dimension for
the pocket. Further, cover or segment 216 defines an
internal space having a specific dimension and configu-
ration which is preferably substantially the same as
tha~ of enclosure 232.
When one or more strips are convoluted into
hose 210, enclosure 232 of a convolution fits conformally
within cover 216 of an adjacent convolution because of
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1 their preferably similar dimensions and con~igurations.
A bonding material 248 is placed between the facing
radial surfaces of leg 220 and side 232b of enclosure
232 to bond ad~acent convolutions o~ strips 212 and
- 5 214 together in a manner similar to that described,
for example9 in U.S. Pat. No. 3,255,780.
The embodiment of FIG~ 4 incorporates all
the advantages of that of FIGSo 1 and 3 and provides
additional ones. For example, the double thickness of
bonded--together axial legs 24 and 26 provide an enhanced
resistance to axially-exerted crushing forces on hose
10. A similar result is obtainable in the embodiment
of hosa 210 shown in FIG~ 4; all that is required is
to increase the thickness of base leg 226. However,
if it is determined that similar resistance to axial-
exerted forces are desired without a decrease in flexi-
bility otherwise resulting from an increased leg thick-
ness, leg 226 may be shortened to decrease its axial
length, so that radially extending legs 218 and 220 of
adjacent convolutions contact or are positioned closer
to one ~nother than depicted. The embodiment of FIGS.
1 and 3 may be somewhat limited in this respect because
legs 24 and 26 require a minimum of contact between
their overlapping surfaces 28 and 30 for adequate
bonding therebetween. Such a requirement is not needed
in FIG. 4.
More importantly, the embodiment of FIG. 4
enables it to utilize more fully the proven advantageous
principles of the construction and flexibility of the
invention described in U.S. Pat. No. 3,255,780. Speci-
fically, those elements, of strip 212 and 214 identified
by indicia 226a and 218 connecting base leg 226 with
crown 222, impart flexibility and support to hose 210.
Accordingly, elements 226a and 218 and crown 222 and
their connecting hinge-like corners, including the
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1 corner between leg 2~0 and crown 222, may be termed
flexible elements. Also, legs 218 and 220 and radial
sides 232a and 232b of enclosure 232 may be termed
support elem~nts in that they help to resist radially-
exerted crushing forces on hose 210. In this respect,because of the preferable close fit of enclosure 232
within cover or segment 216, the two cooperate to
enhance the resistance of the tube or hose against
radial crush.
Further, by placing enclosure 232 at an end
of the strip, it is easier to extrude the strip. ~y
locating bond 2~8 between enclosure side 232b and leg
220, manufacture of the hose is facilitated. For
example, the interlocking hook arrangement of cover
216 with enclosure 232 forms a mechanical connection
which holds the parts together during convolution of
the strip or strips into a hose or tube for a time
sufficient ~or the bonding material at 2~8 to solidify
and tightly bond the surfaces together without slippage
or other movement therebetweenO Also, abutment between
facing edges 226b and 226c of base leg 226 is more
easily ef~ected to resist axial crush on the hose and
to further ensure a smooth inner hose wall defined by
surface 238 of base leg 226~
Although the invention has been described
with reference to particular embodiments thereof, it
should be realized that various changes and modifications
may be made therein without departing the spirit and
scope of the invention.
