Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates generally to tires
and more particularly to uninflated tires mounted on con-
ventional pneumatic rims.
Numerous attempts have been made to construct a
satisfactory non-pneumatic tire, but, in spite of such
efforts extending over many decades, there still exists a
need for an inexpensive non-pneumatic tire having the
performance characteristics normally associated with pneu-
matic tires.
Early tires merely provided a coating of rubber on
a rigid wood or metal wheel. Subsequent efforts led to
resilient walled tires, not unlike pneumatic tires, wherein
the walls had greater rigidity and structural supportive
characteristics than that for pneumatic tires. Such tires
had the shortcoming that they could not provide the desired
weight support function while providing the necessary
cushioning for the load being carried thereby.
Other efforts led to the provision of flexible
walled tires having a central circumferentlal cavity filled
with resilient foam or other cellular structure. These
tires, likewise, met with dissatisfaction in that the foam
or cellular structure frequently tended to break down after
a relatlvely short service life. In addition, extreme
difficulty was encountered with respec-t to retaining the
tlres on the rims.
More racent efforts produced solid cross section
tires of resilient non-cellular material but, again, diffi-
culties have been encountered in retaining such tires on the
rim. Further efforts have led to flexible wall tires having
interior circumferential cavities extendin~ thereabout ~
with the cross sectional configuration of the walls of such
tires being somewhat V-shaped with the apex thereof riding
on the ground to provide somewhat o~ a bridge characteristic
in transmitting the force on the tire rim to the tread
surface making contact with the ground. A particular short-
coming experienced in testing tires of this construction is
that uninflated fle~ible wall tires of this type tend to
build up somewhat of a bulge or wave immediately ahead of
the point where the tire makes contact with the ground. This
phenomenon, which may be referred to as a "standing wave",
is the source of one of the major difficulties experienced
in such tests. This may result in the tire crawling, or
walking, around the rim at a rate proportional to the speed
of rotation. The so called standing wave immediately ahead
of the ground contact point, or "footprint" of the tire
results in the tire attempting to climb such standing wave
then encourltering rolling resistance. Further, the bulge
tends to force the tire away from the rim on which it is
mounted and such tendency is compounded when torque is
applied to the rim. When a torque is applied to the loaded
rim the bulge on the backside of the footprint is exagger-
ated frequently resulting in a gap opening up between the
tire and rim and sometimes results in the tire itself
dismounting the rim when lateral forces are applied between
such tire and rim, as for ins~ance during a turn of the
front wheel or similar maneuver.
Efforts to solve this problem have led to testing
various bonding materials for bonding the wall of the tire
directly to the rim but with the present state of the ar-t,
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no such practical bonding materials have been found and
even if such material were available, i-t would suffer the
shortcoming that the aforementioned standing wave would
still be devaloped to some degree and the absolute anchoring
of the radially inner edge~ of the tire sidewalls to the rim
to positively prevent shifting thereof would result in
extreme shear stresses being applied to such tire as a
result of such standing wave, thus rapidly fatiguing and
deteriorating the tire itself.
Thus, there still exists a great demand for a non-
pneumatic tire whicn may be easily and conveniently re-
movably mounted on a conventional rim and which will provide
the desired weight carrying function and cushioning during
operation without building up a roll resisting standing wave
ahead of the tire footprint and which will avoid accidental
dismounting of the tire from the rim during operation.
The present invention is characterized by a tire
formed with a r~dially outwardly facing tread surface and
having radially inwardly and outwardly angled oppositely
disposed side walls which engage the tire rim on the radially
inward extremities thereof and is formed with radially
inwardly extending retaining flanges received on the axially
inner side of the rim mounting flange6, the space between
the side walls forming an interior cavity. Formed within
such interior cavity, is an array o~ webbing formed with
axially extending interrupter webs which maintain the
retaining flanges and side walls urged axially outwardly to
prevent disengagement of the retaining flanges from the rim
mounting flanges while providing a degree of flexing of such
side walls and tread as each individual web passes between
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the rim and entire support surface. Such interrupter webs
serve the further function of interrupting this tendency of
the tire to build up a standing wave as the weiyhted rim and
tire rotate over a support surface.
More specifically the invention is a non-pneuma~ic
tire to be mounted on a rim with annular mounting flanges
spaced apart a predetermined axial distance, said tire
comprising: a resilient circumferential tread wall having a
radially outwardly facing tread surface; a pair of axially
spaced apart elastic sidewalls projecting radially inwardly
from said tread wall and formed with shoulders to nest on
said respective mounting flanges for bearing, in radial
compression, a load on said rim and co-operating with said
tread wall to form a circumferential cavity; a pair of
axially spaced apart elastic annular retained flanges
projecting radially inwardly from said respective sidewalls
for being stretched over said rim mounting flanges to be
held captive on the axially inner sides of said mounting
flanges; and a plurality of radially projecting resilient
axial interrupter webs spaced apart substantially equidis-
tant about the circumference of said cavity, extendingaxially between said sidewalls and connected thereto through-
out substantially the radial length of their respective
opposi-te extremities, said webs being flexible in their
respective axial plane to yieldingly support said sidewalls
against collapse axially inwardly from said mounting flanges.
The tire may also incorporate an endless annular
elastic band extending about such circumferential cav:ity and
connected with each of the axially extending webs to support
such webs against buckling as the side walls and retaining
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flanges are urged axially inwardly thereag~inst as they
perform their weight support function. A150, endless
elastic belts may be embedded in the retaining flanges to
co-operate with such flanges and the side walls in resisting
radially outwardly expansion of the tire during high speed
operation and resultant disengagement of the tire~from the
rim.
Aspects of the invention are illustrated, merely
by way of example, in the drawings, in which:
Figure 1 is a partial cut away perspective view of
a tire of the present invention mounted on a rim;
Figure 2 is a partial cut away perspective view,
in enlarged scale, of a portion of the tire shown in Figure
l;
Figure 3 is a partial interior view looking
radially outwardly from the bottom of the section of tire
shown in Figure 2;
Figure 4 is a sectional view, taken through a
modification of the tire shown in Figure l;
: 20 Figure.5 is a radial sectional view taken along
the line 5-5 of Figure 2;
Figure 6 is a partial side view of a second
embodiment of the non-pneumatic tire of the present in-
vention;
Figure 7 is a transverse sectional view taken
along the line 7-7 of Figure 6;
Figure 8 is a transverse sectional view o~ a third
embodiment of the non-pneumatic tire of the present in-
vention; and
Figure 9, which is on the first sheet of drawings,
2~
is a transverse sectional view of a fourth embodiment of the
non-pneumatic tire of the present invention.
The non-pneumatic tire 10 (Figure 1) of the
present invention is intended to be mounted on a wheel, such
as a conventional bicycle wheel 12, which may be a central
hub 14 carried central of such wheel by means of bicycle
spokes 16. Referring to Fi~ure 2, the tire 10 includes,
generally, a radially outer tread wall 68 having a radially
outwardly facing tread surface 30 and angles axially out-
wardly in opposite directions and radially inwardly to formoppositely angling side walls 26 and 28 which then turn to
project radially inwardly to terminate in oppositely disposed
retaining flanges 20 and 22. The tread wall 68, opposite
side walls 26 and 28, and retaining ~langes 20 and 22 co-
operate to form a circumferential cavity 36 which is separatedinto discrete segments by means of resilient radially
extending interrupter webs 40 which are circumferentially
spaced equidistant about such cavity 36 to be disposed in
spaced apart axial planes and co-operate with a central
radially projecting elastice support band 42. The tire 10
is preferably constructed of an elastomer such as polyure-
thane and, in its relaxed position of the circumference, is
about 90% that of the rim 12 such that the tire itself and
suppoxt web 42 will be maintained in a stretched position on
such rim to provide structural integrity of the tire and
maintain it on such rim. Preferably elastic nylon belts or
beads 56 and 58 are embedded in the reta.ining ~langes 20 and
22 to provide retaining forces for retaining such tire on
the rim 12.
While the tire 10 may take many different configura~
3LO~
tions, it is important that it be hollow t~ form the circum-
ferential cavity 36 and that the webs 40 be spaced equidis-
tant about such cavity and connect on their axial opposite
ends with the retaining flanges 20 and 22 and with the side
walls 26 and 28 to restrict against collapse thereof when
weight is applied to the rim 12. The elastic annular band
42 is conveniently joined on its radially outer extremity
with the tread wall 68 and projects radially inwardly to the
annular plane of the radially inner edges of the webs 40.
Referring to Figure 2, the exterior surfaces of
the side walls 26 and 28 slope axially outwardly radially
inwardly and at their radially inner extremities, turn
axially inwardly to form ears or lobes 41 and 43, resp~ct-
iv,ely and then cup radially inwardly to form radially
inwardly openi~y nesting shoulders 45 and 47, which nest
against the rounded radially outward extremities of the
. respective opposite rim flanges 72 and 74 (Figure 1), of the
; rim 12O
Still referring to Figure 2, the interior cavity
36 is formed in its radlally outward extremity with opposite
outer surfaces 44 and 46 which angle axially outwardly and
radially inwardly to then turn and extend generally radially
inwardly to form oppositely disposed side surfaces 48 and 50
defining the interior surfaces of the portion of the side
walls 26 and 28 and also of the retaining flanges 22. With
continued reference to Fi.gure 2, in the particular molding
procedure employed for molding.khe tire 10, stand-off
supports are employed for supporting the elastic beads 56
and 58 in the mold thus leaving windows 60 in the radially
inner edges 62 and 64 of the retaining flanges 20 and 22
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which exposes the elastic beads 56 and 58. Since this
particular feature serves no important part of the tire of
-~ the present invention, it will not be discussed further. The
elastic nylon belts 56 and 58 in the preferred embodiment
have a tensile strength of 270 lbs/sq inch.
While the minimum number of axially extending
interrupter webs ~0 necessary for operation of the tire of
the present invention has not been specifically determined,
tests have been conducted which reveal that for a conven-
tional 27 inch diamèter 10 speed bicycle tire, the number ofwebs 40 should be no less than 16.
Such tires employing sixteen e~ually spaced webs
have been tested with success and it is believed that webs
at less than 22.5 degrees apart for a 27 inGh diameter wh,eel
would not per~orm satisfactorily. In the preferred embodi-
ment 72, such webs 40 are spaced equidistant about the
circumference of the cavity 36l thus placing such webs at 6
degree intervals thereby ~orming 72 compartments, generally
designated 70,-having the opposite angular ends thereof
formed by the webs 40 and *he radially outer walls thereof
formed by the tread wall 68 and the axially opposite walls
~ormed by the side walls 26 and 28 and flanges 20 and 22.
With this arrangement, three of such webs 40 are flexed at
all times when the rim is loaded with a somewhat standard
weight of 50 pounds or more.
The tire 10 shown in Figures 4 and 5 is essen-
tially the same as that shown in Figure 1, except that the
opposite side walls 26' and 28' are formed to pro~ect
axially ou-twardly and radially inwardly Erom the tread wall
30' and to ha~e their medial portions bulge somewhat out-
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wardly and then to form the lobes 41' and 43' at their
radially inward extremities with somewhat of a more curved
appearance and then to form the nesting shoulders 45' and
47' of their axially inward extremities. Gripping ribs 52
and 54 are formed in the axially outer walls of the re-
taining flanges 20' and 22' for engagement with the res-
pective interior surfaces 76 and 78 of the rim mounting
flanges 72 and 74.
In operation, when it is desired to mount the non-
pneumatic tire of the present in~ention on a conventional
bicycle rim 12, it is only necessary to remove the con-
ventional pneumatic tire and the tire 10 of the present
invention may be stretched onto such rim Since the tire
10 for a 27 inch rim is only about 24 inches in diameter in
its relaxed position, significant stretching thereof is
necessary to mount the tire on the rim 12. This can easily
be accomplished by positioni.ng the retaining flanges 20 and
22 along the side thereof within the rim flanges 72 and 74
and then threading such tire onto the rim about the re-
mainder of the periphery of such rim while holding thealready mounted portion on the rim. This can be accom-
plished by merely extending a flat tool entirely across the
radially outer extremities of the rim flanges 72 and 74 thus
stretching the entire tire, includins the elastic beads 56
and 58, as the tool is advanced about such rim 12. In this
regard, it is important that the belts 56 and 58 have a
relaxed circum~erence significantly less than that for the
radially outer extremities of the mounting ~langes 72 and 74
to thus cause such elastic belts 56 and 58 to resiliently
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hold the flanges 20 and 22 retained interiorly behind -the
rim mounting flanges 72 and 74. A relaxed circumference of
about 90~ of this maximum rim flan~e circumference has been
found acceptable for polyurethane having a Shore hardness of
65 on the A scale to provide for betw~en 7 and 10~ elonga-
tion upon stretch for mounting on the rim 12.
Once the tire 10 has been mounted on the rim 12,
the supported bicycle is ready to be ridden. As weight is
applied to the hub 14 and through the spokes 16 to the rim
12 and, consequently to the tire 10, the weight on such rim
will act downwardly thereon and against the xespective
shoulders 45 and 47 formed by the inner extremities of the
side walls 26 and 28. It will be appreciated that the force
of such weight will, because o~ the axially outwardly and
radially inward slope of the side walls 26 and 28, tend to
bulge the medial portions of such side waIls 26 and 28
axially outwardly. Such a~ial outward flexing of the
central portion of such side walls 26 an~ 28 will be res-
isted by the tensile strength of the interrupter w~bs 40 as
such webs pass between the rim and supporting surface
therefor. Further, since the elastic band 42 is under
significant tension, it will serve to hold the medial
portions of such webs 40 in the same axial plane as the
axially outer extremities thereof, thus preventing buckling
or torqueing thereof and consequent axially inward fléxing
of the retaining flanges 20 and 22 causing them to pull away
from the rim mounting flanges 72 and 74.
Experimentation has proven that the interrupter
webs 40 perform even greater functions than resisting the
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s
tendency of the medial porkions of the side walls 26 and 28
to flex outwardly upon loading thereof and in maintaining
the mounting 1anges 20 and 22 urged outwardly against the
mounting flanges 72 and 74 of the rim 10. This important
feature, while not being entirely understood, is of great
importance in retaining the tire 10 on the rim 12 during
operation of such tire at higher speeds. Studies of non
pneumatic bicycle tires and the like have shown that there
is a tendency for the loaded tire to squat somewhat as it
passes between the rim and supporting surface thus flatten~
ing the tread area and forming what is commonly referred to
as a footprint. The size of this footprint is directly
-proportional to the weight being carried on the tire and is '~
increased when the flexibility of the tire is increased. As
a result of such squatting of the tire, somewhat of a bulge
is created both forwardly and rearwardly of the footprint,
which develops a tendency in the tire to separate from -the
rim, particularly at highex speeds~ At lower speeds, the
bulges are normally symmetrical forwardly and rearwardly of
the footprint but when a torque is being applied to the
whael hub 14 (Figure 1), the bulge rearwardly of -the foot
print in the past has typically become even greater than
that forwardly of the footprint, thus increasing the resis-
tance to rolling of the rim and decreasing the efficiency of
the tire. The bulge forwardly of the footprint, commonly
referred to as a "standing wave", has in prior art tires
frequently resulted in separation of the tire from the rim
creating a gap between the tire and rim and, in many lnstances,
resulting in unintentional dismounting of the tire from the
rim. This is one of the problems that the tire of the
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present invention overcomes.
The interrupter webs 40, as they pass between the
rim and support surface, serve -to interrupt this standing
wave eliminating the tendency of the tire to dismount itself
at higher speeds. As mentioned hereinabove, the particular
phenomenon of the interrupter webs 40 in minimizing, or even
eliminating, such standing wave is not fully understood, but
it is believed that the axial resistance provided by such
webs to axially outward squatting of the side walls 26 and
28 serve to interrupt the tendency of the resilient polyure-
thane to flow along the rim forwardly and rearwardly of the
footprint, thus preventing a buildup of the standing wave
and consequent walking of the tire around the rim.
Referring to Figure 4, it will be appreciated that
lS the elastic annular band 42 serves to tie the central
portions of the interrupter webs 40 together and co-operates
with the side walls 26' and 28' to form what may be referred
to as individual torsion boxes which provide yielding
support for the rim 12. The annular band 42, when weight is
applied directly over the hub 14, has its longer cross
sectional dimension disposed centrally beneath such weight
to co-operate with the side walls 2~' and 28' and webs 40,
in yieldingly resisting radially inward flexing of the tread
wall 68'.
During cornering, when a lateral force L (Figure
4), is applied to the tread surface 30' relative to the rim
12, the side walls 26' and 28' will be flexed causing the
elastic band 42 to bend out of the vertical plane 80 of the
rim 12, thus allowing the compressive force C to bend the
annular dimension of such band 42 even farther, thus reducing
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the distance between such lateral ~orce L and the bead 58'
on the outside of the corner being turned. This reduces the
lever arm between such lateral force L and the elaskic bead
58', thus reducing the ~orce tending to stretch such bead
58' and lessens the tendency to expand such bead to a point
where it may exceed the diameter of ~he outside rl~ mounting
flange 74, and freeing the retaining flange 22 to escape
from the interior of such mounting flange 74. It will be
appreciated that this tendency of the tire to squat depends
on the flexibility of the material from which such tire is
constructed. For the polyurethane incorporated in the tire
shown in Figure ~, a 75 5hore hardness on the "A" scale has
been found pre~erable. For other lower profile tires having
a lesser distance between the rim and exterior tread surface
30, a Shore hardness as low as 65 on the "A" scale has been
found desirable.
The non-pneumatic tire shown in Figure 6 is
similar in construction to the tire shown in Figures 1
through 5, except that it incorporates exterior traction
ribs 84 (E'igure 7) that not only act to resist collapse of
the side walls 26 and 28 when weight is applied thereto, but
provide the additional feature of enhancing the traction of
the tire when operating in a soft terrain or during co-
rnering thereof. It will be appreciated that the webs 84
which are on an axial plane, bulge outwardly away from the
outwardly and radially inwardly sloping side walls 26 and 28
to thus provide so~lewhat of a beam like construction res-
isting collapse of such wall as weight is applled there-to.
The non-pneurnatic tire 90 shown in Figure 8 is
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9~
also similar to tire shown in Figures 1 through 5 except
that it is somewhat of a lower pro~ile having a shorter
distance between the rim and tread surface 92 and provides
~or interior and exterior grippin~ of the mounting flanges
114 and 166 o~ the bicycle tire rim 115. The tire 90
includes a radially outwardly disposed circumferential tread
wall 92 and is formed with radially i.nwardly and axially
outwardly curved side walls 94 which terminate at their
axially inward extremities in respective axially inwardly
facing central grooves which fit over the exterior edges of
the mounting flanges 114 and 116 and define respective
anterior and exterior retaining flanges 98, 100, 102, and
104. Also, interior and exterior elastic belts 106, 108,
110 and 112 are embedded within the respective retaining
flanges for resisting e~pansion of such tire and possible
dismounting from the rim. The interrupter webs 122 are
comparable to the webs 40 and the annular elastic support
band 124 is comparable to the support band 42 shown in
Figure 4.
Consequently, the tire shown in Figure 3 is
similar to the tire shown in Figures 1 through 5 except that
it is a somewhat lower pro~ile and provides for interior and
exterior retaining flanges and elastic beads.
The tire shown in Figure 9 is similar to the tire
shown in Figure 4 except tl~at it includes a central radial
band 131 projecting radially inwardly beyond the radial
inner extremities o~ the side flang~s 20' and 22', and is
enlarged in cross-section on its radial inner extremity to
form a circular conduit 133 having a rigid metallic bead 135
telescoped therethrough. Interrupter web 137 are spaced
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equidistant about the ci~cumference of the tire and taper
axially downwardly and inwardly from the flanges 20' and 22'
to join with the radial inner extremity of the band 131.
From the foregoing, it will be apparent that the
non-pneumatic tire of the present invention is of hollow
construction, thus minimizing the use of the petroleum base
products that may be used in the polyurethane from which it
may be constructed and provides for performance comparable
to a pneumatic tire while relieving the problems normally
connected with non-pneumatic tires as related to accidental
dismounting thereof with resistance to rolling.
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