Note: Descriptions are shown in the official language in which they were submitted.
57
Backeround ~f the InYention
The foregoing abstract is not to be taken as limit-
ing the invention of this application and in order to
understand the full nature and extent of the technical
disclosure of this application reference must be made
to the accompanying drawings and the following detailed
description.
mis invention relates generally to pneumatic
tires and more particularly to tires of a closed toroidal
type of simplified radial construction, to tire and rim
assemblies incorporating same~ and to the method of
making same.
"Closed tube tire" and "closed toroidal tire" as
used herein will be understood to mean a tire providing
a completely closed inflation chamber capable alone~
without being mounted on a rim~ of containing fluld
pressure therein higher than the surrounding atmospheric
pressure. In this specification, the terms "closed tube
tire" and "closed toroidal tire" are used and intended
to dlstinguish from open-base tires having generally
horseshoe-shaped~ radial cross-sections and spaced apart
beads, thus not being capable of containing fluid pressure
without being mounted on a rim
When used in this specification~ a substantially
inextensible material refers to one whose elongation at
tensile rupture does not exceed 5 percent. A cord formed
of a substantlally inextensible material may have an
elongation at tensile rupture in excess of ~ percent
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i9S7
"Radial" when used herein with respect to the
dlrection of the cords of any reinforcing ply means
that such cords form an angle greater than 75 degrees.
All angles or incllnations of tlre components or
portions thereof unless otherwise speci~ied herein are
to be taken with respect to a plane which is perpendicular
to the axls of rsvolution of the tire.
Radial plane of a tire means any plane passing
through that tire and containing its axis of revolution.
m e state o~ development of pn~umatic automotive
tires today is such that vehicle disablement due to tire
failure is a relatively infrequent occurrence. Tires
having radially oriented carcass plies are in widespread
use Of growing importance is the need to conserve
materials~ particularly those which are petrochemical in
nature. It is desirable to reduce tire and rim weight to
decrease vehicle fuel consumption~ These concerns have
made it desirable to provide a lightweight pneumatic tire
and rim assembly suitable for temporary use~ especially
with vehicles equipped with radial tires. It is also
desirable to provide a tire which is capable of increased
load-carrying capacity for its size and weight in com-
parison to known open-base tires. Although a closed
tube tire may satisfy these requirements~ closed tube
tires such as are known today are relatively complex
structures. Manufacture of a closed tube tire having
radial sidewalls acco~ding to known methods is quite
costly. One method ln~olves winding the carcass cords
9S7
or wrapping of the carcass ply about a toroidal mandrel,
applying elastomer layers, belt reinforcement layers,
and tread layers, curing of the assembly, and them
removing the mandrel by dissolving same and washing out
the residue through one or more valve openings. In
another method, the tire carcass is formed upon a man-
drel, then slit to remove it from the mandrel, then
rejoined and inflated prior to completion of the assembly.
According to one aspect of the present invention there
is provided a closed tube tire having a carcass ply of sub-
tantially parallel cords extending continuously and com-
pletely around a circumferentially elongated segment of
said tire, said cords of said carcass ply in the crown of
said tire being inclined to a plane perpendicular to the
axis of revolution of said tire, said cords of said
carcass p]y in the sidewalls of said tire being substantially
radial, said cords of said carcass ply in the base of
said tire being oppositely inclined to said plane an
amount greater than in the crown of said tire, and in the
crown of said tire a belt ply of substantially parallel
cords which are oppositely inclined to said cords of
said carcass ply in said crown.
According to another aspect of the present invention
there is provided a closed tube tire and rim assembly,
said tire having a carcass ply of substantially parallel
cords extending continuously and completely around a
circumferentially elongated segment of said tire, said
cords of said carcass ply in the crown of said tire being
inclined to a plane perpendicular to the axis of revolution of
.
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957
.
o~ said tire, said cords of said carcass ply in the
sidewalls of said tire being substantially radial, said
cords of said carcass ply in the base of said tire being
oppositely inclined to said plane an amount greater than
in the crown of said tire, and in the crown of said tire
a belt ply of substantially parallel cords which are
oppositely inclined to said cords of said carcass ply
in said crown, said tire being bonded at its base to
an annular rim.
According to yet another aspect of the present
invention there is provided a method of making a closed
tube tire comprising forming a cylinder of a carcass
ply of rubberized cord fabric the cords of which are
sub~tantially parallel and which form an angle other
than a right angle with the circumferential direction of
said cylinder, adhering a layer of elastomer composition
to the radially outermost surface of said carcass ply
cylinder, forming an aperture through said cylinder and
inserting a valve core into said aperture, lifting the
edges of said carcass ply and elastomer composition layer
: radially outwardly and drawing the edges of said carcass
ply and said layer axially toward one another, joining
said edges radially outwardly of the base of said tire
to form a flattened tube, adhering to a radially outer
surface of said tube, as a narrower ply a belt ply of
substantially parallel cords with the cords of said belt
ply being oppositely inclined to and forming a lesser
angle than the radially outermost portion of the cords
... . .
957
of said carcass ply with the circumferential direction
of said tube, and inflating said tube into a toroidal
shape.
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:
957
Brief Description of the Drawings
Fig 1 is a perspective view of a broken away
portion of the simplified radial tube tire with
additional structure broken away to show internal ~ ~ :
detail;
Fig 2 is a radial cross-section of a portion of
the building drum with the components of a simplified
radial tube tire placed thereon but not yet made into
a closed tube. The step of turning up the edges of the
material to form a closed tube is indicated in dotted
lines and the thickness of the plies somewhat exaggerated;
57
Fig 3a is a schematic plan view illustrating the
cord arrangements of the green tire prlor to shaping
from cylindrical to toroidal configuration;
Fig 3b illustrates schematically in plan view the
cord arrangement of the tire after expansion into
toroidal configuration;
Fig 4 is a radial cross-section of a rim suitable for
use in building~ curing~ and operating the simplified
radial tube tire.
DescriPtion of the Invention
Referring to Fig 1, the general overall appearance
of the completed closed tube simplified radial tire 10 is
seen The elastomer-coated first or carcass cord ply 12
has three distinct angular regions~ according to location
in the tire In the base or rim-contacting portion 14
of the tire 10 each cord 16 of the carcass ply 12 has an
angle substantially identical to that of the carcass ply
in the green tire~ e.g about 77 degrees. In the sidewalls
18~19 each cord 16 of the carcass ply 12 forms an angle
of about 90 degrees; in the crown 20 each cord 16 o~
carcass ply 12 lies at a low angle~ e.g. about 45 degrees~
and is in the opposite direction when compared to the
cords in the base 14. First transition zones 22~24
connect that portion of carcass ply 12 in base 14 and
sidewalls 18~19~ respectively~ of tire 10. If~ as shown~
anchoring means are present~ first transition zones 22~24
begin at the axially outermost edges of the anchoring
means 23 of tire 10. The path of each cord 16 in these
first transition zones is curved. Second transition zones
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957
25,26 exist at the shoulders 15~17~ respectively~ of
the crown 20 of tire 10 and coincide approximately with
the axially outermost edges 29,30 of the belt 28. The
path of each cord 16 in ~ones 25,26 is also curved.
Each cord 16 of the carcass ply 12 completely encircles
in predominantly axial direction a circumferentially
elongated segment of the tire~ said segment being defined
by two circumferentially spaced radial planes of the tire.
A single carcass ply cord 16 does not lie in a single
radial plane. The ends of any given carcass ply cord 16
are circumferentially displaced from one another. me
ends of the carcass ply cords 16 overlap in the crown 20
of the tire The amount of overlap may be minimal~ that
is~ an amount sufficient to effect a splice and able to
withstand shaping by inflation of the green~ i.e uncured,
tire or may be equal to the belt ply 28 in width to provide
additional reinforcement in the crown of the tire. me
belt ply 28 is comprised of cords 31 which are substan-
tially inextensible. The belt ply 28 is preferably of
about the same width as the tread 36 of the tlre. Cords
31 of belt ply 28 lie at a very low angle~ for example~
about 15 degrees and are opposite in direction when com-
pared to that portion of the cords 16 of the carcass ply
12 l~lng immediately radially inward thereof. Although a
single belt ply is shown~ multiple belt plies may be
employed Liner 32 is provided to prevent permeation of
the inflation gas through the structure. It is believed
that a cured elastomeric composition inflation tube could
be substituted for liner 32 at the time of manufacture of
3S7
the tire. Valve 34 is provided to enable inflation of
the structure. Valve 34 could also be located in one of
sidewalls 18~19 instead of in the base 1~ of the tire.
Conventional tread 36 and sidewalls 18~19 are placed
radially outward of the carcass/belt structure to complete
the tire.
Fig 2 illustrates a preferred method of fabrication of
a simplified closed toroidal radial tire Sidewalls 18~19
are placed on the cylindrical drum or former 38. A carcass
ply 12 of cord fabric, the cords 16 of which lie at a
relatively high angle but less than 90 degrees, ~or
example~ about 77 degrees with respect to the lengthwise
direction of the carcass ply 12~ is placed upon the drum
38 and its longitudinal ends joined to form a complete
cylinder. me angle Or the cords 16 of the carcass ply 12
is other than a right angle with respect to the circum-
ferential direction of the cylinder. A layer 39 of
elastomer composition is then added to form the impermeable
inner liner 32 of the tire. Anchoring means 23 of a
substantially inextensible material~ for example~ metallic
wire~ fiberglass, or high modulus organic fiber~ or the
like, such as hoops 40 are placed upon layer 39 at
axially spaced apart locations corresponding to the width
of the base 14 of tire 10 and centsred relative to the
edges 41~42 of the ply 12. An aperture 44 îs formed
through the carcass ply cylinder between the anchoring
hoops 40~ and an inflation valve 34 is inserted therein.
A suitable recess 46 should be provided in the building
drum 38 for acceptance of the valve. The radially outer~
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~ 57
most qurface 47 of the liner elastomer composition layer
39 is then treated with a suitable anti-adhesive selected
from those well known in the art. It is preferable to
utilize a plastic film (not shown) such as polyvinylidene
chloride as an anti-adhesive to insure that the anti-
adhesive does not flow into and contaminate the carcass
ply/liner assembly splices. Following application of the
anti-adhesive layer the edges 48~49 of the carcass ply/
liner assembly are li~ted radially outward from the drum
38 and pulled axially toward one another until they overlap
in the radially outward portion of the structure. me
overlapped carcass ply/liner assembly is shown by the
dotted lines of Fig 2. These may be interleaved (not
shown). The overlapped area need not be centered with
respect to the centerplane CP of the structure~ but
preferably is centered. m e overlapped area 50 is stitched
tightly in conventional manner to form a flat tube. A
single belt ply 28 ha~ing cords 31 at an angle opposite
to those o~ the crown area carcass ply 12 and much
smaller~ e.g. about 20 degrees~ is then centered over the
anchoring hoops 40 and stitched thoroughly to the carcass
ply 12. The structure is completed by addition of a tread
36 as in a conventional tire The completed structure
is then removed from drum 38 A slightly collapsible or
tapered drum (neither is shown) may be used to facilitate
removal of the completed green tire.
The green tire preferably is then placed in a suitable
curing mold cavity (not shown) and the valve 34 coupled
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957
to an in~lation source. IJpon application of the inflation
pressure the structure expands from a flat cross-sectional
configuration to assume the internal shape of the mold~
that is, to a substantially toroidal configuration. ~or
it to do so~ the carcass ply and belt ply cords 16~31 must
undergo considerable movement relative to one another.
mese movements are schematica]ly illustrated in Figs 3A
and 3B. me initial arrangements of the cords 16,31 are
shown in Fig 3A In Fig 3A, a single cord 16 of the
carcass ply 12 forms an angle o~ about 77 degrees with
the radially inner layer (indicated by IL) and radially
outer layer (indicated by OL) being oppositely directed.
A single cord 31 of the belt ply 28 forms an angle in
the opposite direction to the radially outermost layer (OL)
of carcass ply 12 of about 20 degrees.
The final arrangements of the cords 16~31 are shown
in Fig 3B. mat portion of each carcass ply cord 16
lying in the base 14 of the tire 10 and between the
axially most distant extremities of the anchoring hoops 40
continues to lie at an angle of about 77 degrees. In
other words, the base 1~ of the tire 10 does not undergo
movement during shaping of the tire mat portion of
each carcass ply cord 16 in the crown 20 of tlre 10 has
moved radially outward from the base 14 and pantographed
to a much lesser angle~ e.g. about 45 degrees~ and con-
tinues to lie in the same direction. Both portions of
each carcass cord 16 underlying the sidewalls 18,19 of
the tire have increased in angle from their init~al angle
957
to become substantially radial, and in the embodiment
shown form an angle of about 90 degrees. Each belt ply
cord 31 has pantographed from its initial angle to a
reduced angle of about 15 degrees.
The anchoring means should be formed of a substantially
inextensible material. Although the nominal level of
stress imposed upon the anchoring means is conslderably
less than that imposed upon the beads of conventional open-
base tires, if the anchoring means are made o~ extensible
mater~al, such extension may allow the tire to move
laterally relative to the rim upon which it is mounted,
which is undesirable
One or more belts (not shown) of rubberized cord
fabric may be substituted for hoops 40. The axially most
distant edges of such belt or belts should lie at about
the same location from the circumferential centerplane of
the tire as do hoops ~0 The cords of such belt or belts
should be of low angle~ preferably in the range of O to
10 degrees. When such anchoring belts are employed, the
~alve core 34 may be inserted through tha anchoring belt
or belts.
The starting angle, i.e. in the unshaped green tire,
for the cords 16 of carcass ply 12 should be relatively
high~ that is~ greater than ~5 degrees but less than 90
degrees~ and preferably from about 60 degrees to 85 degrees.
In the cured tire~ the cords of the carcass ply in the
sidewalls for at least 60 percent of the radial height
o* the sidewalls should be substantially radial, that is~
at an angle of at least 75 degrees. The an~le of the cords
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957
of the carcass ply 12 in the sidewalls 18~19 of the
cured tire will always be greater than the angle of the
cords of the carcass ply in the crown 20 or base 14 of
the cured tire. ~he angle of the cords of the carcass
ply 12 in the crown 20 of the cured tire should be a
relatively low angle~ that is~ not exceedlng 60 degrees.
The lower the angle of the cords of the carcass ply in
the crown of the tire~ the greater their contribution to
circumferential restriction of the tire.
"Blow-up ratio" as used herein is the ratio of the
diameter of the crown portion of the carcass ply at the
centerplane CP of the shaped tire to the diameter of the
crown portion of the carcass ply after being formed into
a flattened closed tube (on the building former) but prior
to shaping by inflation. As the blow-up ratio of the
tire i9 increased~ the amount of cord movement durlng
shaping of the tire is increased~ for the cords of the
carcass ply and for the cords of the belt ply.
m e starting angle for the cords of the carcass ply
for a given desired cured angle is dependent~ in part~ on
the blow-up ratio of the tire. As the blow-up ratio i5
increased~ the starting angle of the cords of the carcass
ply for a given desired cured angle should be decreased.
me starting angle for the cords of the belt ply 28
or plies should be a relatively low angle~ that is~ less
than ~5 degrees~ and preferably less than 35 degrees.
~he cured angle of the cords of the belt ply or plies
should be less than 35 degrees, and preferably less than
~ 5 7
25 degrees me lower the angle of the cords of the
belt ply or plies~ the greater their contribution to the
circumferential restriction of the tire. The practical
lower limit for the starting angle of the cords of the
belt ply or plies is believed to be about 15 degrees
with known cords and fabrics suitable for tire reinforce-
ment. Lower angles are not practical because cord
lock-up (physical interference) occurs at very low
blow-up ratios~ unless the initial cord spacing is so
increased that the fabric is not of sufficient strength.
me introduction of fabrics having higher tensile strength
cords of smaller cross-sectional area and greater distance
between the axes of ad~acent cords will permit use of
lower starting angles for a given blow-up ratio
~he starting angle for the cords of the belt ply for
a given desired cured angle is also dependent in part on
the blow-up ratio of the tire. As the blow-up ratio of
the tire is increased~ the starting angle of the cords of
the belt ply for a given desired cured angle should be
increased.
A tire according to the in~ention may be separately
molded~ or integrally molded with a rim. In the latter
case~ the tire is preferably built and cured upon the rim.
When the tire is bonded to the rim~ the need for anchoring
hoops 40 or their equivalent is eliminated.
When the tire is built and cured upon its rim~ the
carcass ply 12 prior to forming into a ~lat tube, may
not form a true mathematical cylinder but may form a
~ 9 ~7
s]eeve of varying diameter along its axis of revolution
according to the rlm configuration. In the following claims
it is understood that the use of the word "cylinder" or
"cylindrical" with reference to the carcass ply includes
such a sleeve whose diameter varies with location along
its axis of revolution, as well as one of un~aryin~ diameter5
An embodiment of a suitable rim is shown in Fig 4.
The rim 52 is of circular configuration and is adapted
to be fastened to a vehicle wheel disc (not shown). me
rim is preferably of least circumference at its axial
centerplane 53 and increases in gradual manner in circum-
ference from its axial centerplane to its axially most
distant edges 54~55. me rim preferably is of a V-shaped
cross-sectional configuration as shown or of arcuate
cross-sectional configuration (not shown). A cylindrical
rim of unvarying diameter along its axis of revolution
may also be used.
While certain representative embodiments and details
have been shown for the purpose of illustrating the in-
vention~ it will be apparent to those skilled in the artthat various changes and modifications may be made therein
without departing from the spirit or the scope of the
invention.
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