Note: Descriptions are shown in the official language in which they were submitted.
~22~86
The present invention relates to wheel assemblies
for pne.umatic tubeless tires, and more partic~larly to
safety tire and wheeI assemblies and methods of a type
adapted for continued operation upon loss of air pressure
in the tire. Yet more specifically, the invention relates
to wheel rim assemblies of the type having a removable flange
ring for mounting or demounting of a tubeless pneumatic tire
thereon, and to a safety insert device adapted to be disposed
internally of a tire mounted on such a rim for supporting
the tire tread in the deflated condition.
This application is a divisional application of co-
pending application No. 408,006 filed July 26, 1982.
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Backqround and Ob;ect of the Invention
In safety tire and wheel assemblies which include
inserts of the described type, the insert conventionally
comprises a base portion disposed adjacent to the wheel
rim and a second portion projecting-radially from the
rim into the tire cavity or chamber. Upon loss of air
pressure in the chamber, the tire tread collapses against
the second portion of the insert, such that the insert
supports the tire tread with respect to the rim for
continued operation of the vehicle. Priction due to
relative motion between the tire tread and the tread-
supporting portion of the safety insert often causes
overheating and destruction of the insert during con-
tinued operation. This problem has been alleviated to
some extent, but not entirely overcome, by disposltion
of solid or liquid lubricant along the tread-supporting
surface of the insert. However, the relatively soft
material of the carcass liner tends to squeeze the lub-
ricant from between the liner surface and insert, so
that the engaging insert and tire surfaces eventually
are substantially unlubricated.
A goal in the vehicle industry has been to provide
a safety tire and wheel asse~bly which will operate at
a vehicle speed of 30 miles per hour over a distance of
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30 miles following loss of tire pressure without destruc-
tion of the tire or wheel. With the exception of the
safety tire and wheel assembly disclosed in the copending
Canadian application of applicant herein, Serial No. 385,014
, filed September 1, 1981, these industry goals or specifi-
; cations have not been well met by the safety assemblies
previously proposed. The safety assembly disclosed in the
referenced copending application has been found to satisfy
the described industry goal, but comprises a number of
assembly components which contribute to the overall
weight and expense of the insert.
It has heretofore been recognized in the art
that multiple-piece wheel rim assemblies, considered
alone or in combination with safety inserts of the above-
described type, may present a significant safety hazard
if it is attempted to inflate a tire mounted thereon
when the various rim assembly components are improperly
positioned or seated, or to disassemble the rim when
` the tire mounted thereon is inflated. This problem is
particularly acute in the case of high pressure track
tires and the like.
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lZ22186
The present invention provides a safety tire and
wheel assembly and method, and a safety insert adapted for
use therein, which are adapted for operation at a Yehicle
speed of at least 50 km/hr miles per hour for a distance of
5 at least ~0 km following loss of tire pressure, and which are
less expensive and lighter in weight than assemblies, methods
and inserts heretofore proposed capable of approaching or
achieving this industry goal.
The present invention also provides a safety insert
for a pneumatic tire and wheel assembly which is rugged in
operation, and yet is light in weight and does not substan-
tially alter the dynamic and static wheel and tire balance
characteristics.
The present invention still further provides a wheel
rim assembly for tubeless pneumatic tires, including safety
tire and wheel assemblies of the above-described type, which
prevents inflation of a tire mounted on the rim assembly when
the rim assembly components are improperly positioned and/or
which automatically vents the tire cavity to atmosphere should
disassembly be attempted when the tire mounted thereon is
inflated.
According to copending application No. 408,006 there
is disclosed a wheel rim assembly ~10 or 100) for use in a
safety tire and wheel assembly which includes a pneumatic
tubeless tire (12) and an axially incompressible safety in-
sert (14,14A) for retaining the tire bead toes (66,68) on
said rim assembly in the event of loss of inflation pressure
in the tire, said wheel rim assembly comprising rim base
means (16,102) including a rim base (18), a bead retaining
flange (20) integrally carried at an inboard edge of said
rim base, a cylindrical band (24,104) at a flange-remote edge
of said rim base at a diameter less than that of the adjacent
edge of said rim base, demountable flange means (36,110)
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. including a cylindrical hoop (38,112) adapted to be telesco-
pically receiYed from an axially outboard direction oYer said
band, outboard bead retaining flange means (40~ integrally
projecting from one edge of said hoop and an inboard edge
(44,114~, annular resilient sealing means (46,116) disposed
between said inboard edge and an opposing surface (26,108)
of said rim base means, means (48-54, 120-122) for axially
clamping said demountable flange means on said rim base means
with said sealing means being captured in compression between
said inboard edge and said opposing surface so as to seal
against air leakage, and air bleed passage means (34,124) in
~aid band outbcard of sealing méans and normally sealed from the ~re
cavity by said sealing means, improper mounting of said.demountable flange
m~ on said rim base means permitting air leakage past said sealing means
through said air bleed paSSaCJe means to a~here.
According to the present invention there is provided
a safety tire and wheel assembly comprising a vehicle wheel
including a wheel rim having axially spaced bead flanges, and
a rim base; a tire having axially spaced bead toes and a
circumferential tire tread; and safety means including an
axially incompressible first portion extending circumferen-
tially around said rim and having axially spaced side edges
clamping said bead toes against said bead flanges such that
said tire tread is spaced radially outwardly of said rim base
to define a tire cavity, said wheel rim including means for
inflating said tire cavity and means for preventing inflation
: of said tire cavity in the event of improper assembly of said
safety tire and wheel assembly.
The present invention will be further illustrated by
way of the accompanying drawings, in which:-
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;. FIG. 1 is a sectional view of a presently preferred
embodiment of the safety tire and wheel assembly provided by
~: 35 the invention taken in a radial plane substantially along the
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line l-l in FIG. 2;
FIG. 2 is a fragmentary partially sectional and par-
tially elevational view of the tire and wheel assembly as
viewed substantially along the line 2-2 in FIG. l;
FIG. 3 is a fragmentary sectional view on an enlarged
scale taken substantially along the line 3-3 in FIG. 2;
FIG. 4 is a fragmentary elevational view on an en-
larged scale as viewed substantially along the line 4-4 in
FIG. l;
FIG. 5 is a sectional view taken along the line 5-5
in FIG. 3; and
FIG. 6 is a view similar to that of FIG. 1 showing
a modified safety tire and wheel assembly in accordance with
the invention.
In the following description and claims, directional
adjectives such as "inboard" and "outboard" are taken with
reference to preferred orientation of mounting of the wheel,
etc. on a vehicle, and no undue limitations should be in-
ferred therefrom where such directional adjectives are notessential to operation of the structural and functional fea-
tures of the invention.
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FIGS. 1-5illustratesa presently preferredembodiment
of a safety tire and wheel assem~ly in arcordance with the
inventionascomprising a wheel assembly 10, a tubeless pneumatic
tire 12 mounted thereon and a safety insert 14 carried by wheel
assembly 10 internally of tire 12 for supporting the latter in
the vent of tire deflation. ~heel assembly 10 includes a first
rim segment 16 having a cylindrical rim base lB and an inboard
bead retaining flange 20 integrally projecting therefrom and
coupled thereto by a 15 bead seat 22. A circumferentially
continuous cylindrical band 24 has a diameter which is less
than that of rim base 1~ and is coaxially integrally connected
thereto by the radially out~7ardly and axially inwardly angulated
shoulder 26. A circumferential array of axially extending air
bleed passages or channels 34 tFIGS. 3 and 4) are formed as
radial depressions in the cylindrical outer surface of band 24
at a preferred spacing of substantially 45. As best seen in
FIG. 3, channels 34 extend axially throuyhout the cylindrical
portion of band 24 but not into the angulated shoulder 26.
A wheel mounting disc generally indicated at 28 is
integral with an edge of band 24 remote from flange 22, and
includes hub opening 30 and stud opening 32 for mounting wheel
assembly 10 Oll a vehicle in the usual manner. ~s best seen in
FIG. 1, disc 28 tapers uniformly in thic~ness from a maximum in
the region of hub opening 30 and stud opening 32 to a minimum at
the outermost disc edge integral with rim segment 16. Rim
segment 16 is of substantially uniform thic~ness through-
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out. Rim segment 16 with integral disc 28 may be formed in ablanking and spinning operation, followea by a forming operation
in which channels 34 are stuck in rim band 24 at a spacing of
45 from each other.
WheelassemblylO furtherincluaesa second rim segment
36 which comprises a cylindrical hoop 38 adapted to be slidably
and telescopically received over band 24, and an outboard bead
retaining flange 40 integrally coupled to hoop 38 by the outboard
15 bead seat 42. A lip 44 projects axially in~ardly and
radially outwardly from the flange-remote edge of band 38 for
sealingly capturing in assembly against shoulder 26 an annular
resilient O-ring seal 46. ~ plurality of threaded studs 48 are
affixed as by ~elding internally of band 24 on rim segment 16
and project axially outwardly therefrom through corresponding
openings 50 (FIG. 1) in disc 28. Studs 48 are preferably spaced
45 from each other and symmetrically alternate in
circumferential position ~ith air bleed channels 34. That is,
each air bleed channel 34 is struck in the forming of rim segment
16 mid-~ay bett7een an associated pair of disc openings 50. An
annular clamping ring 52 is received over the outboard ends of
studs 48, and a plurality of locknuts 54 are received over t'ne
corresponding threaded stud ends for clamping rim segment 36
onto rim segment 16, WitllO-ring 46 being captured in compression
bet~een lip 44 and shoulder 26.
With the rim segments assembled as shot~n in FIG. 1,
the internal cavity of tire 12 is sealed by O-ring ~6 so that
the tire may be inflated through valve 45 (FIG. 2) and operated
in the usual manner. If clamping ring 52
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and rim segment 36 are not in the fully assembled condi-
tion, or if it is attempted to dissassemble rim segment
36 by removal of nuts 54 with the tire inflated, com-
pression forces on sealing ring 46 are removed and any
pressurized air within or entering the tire cavity is
vented to atmosphere past the O-ring and between hoop
38 and band 24 through air bleed channels 34. It will
be noted in particular in accordance with a preferred
embodiment of the invention that sufficient threads
extend from nuts 54 in the fully assembled positions
of nuts 54 thereon that, in the event that the nuts are
loosened during a disassembly operation with the tire
inflated, lip 44 on rim segment 36 will move out of
. sealing engagement with O-ring 46 and thereby vent the
tire cavity to atmosphere through air bleed passages 34
before all of the nuts 54 are removed from studs 48.
Safety insert 14 comprises an inner band 6C extend-
ing around rim base 18. Band 60 has axially projecting
outboard and inboard edges 62, 64 which engage respec-
tive bead toes 66, 68 of tire 12 and clamp such bead
toes against corresponding outboard and inboard bead
retaining flanges 40, 20. A plurality of axially extend-
ing ribs 70 project radially inwardly from band 60.
Insert 14 further includes an outer band or ledge 72
integrally mounted coaxially with inner band 60 by a
circumferential array of axially extending circum-
ferentially spaced support struts or columns 74. As
: best seen in FIGo 1~ insert 14 is generally I-shaped as
viewed in radial cross section, and is centrally and
symmetrically positioned with respect to the axial center
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line or plane of wheel 10. The volume between circum-
ferentially adjacent columns 74, and between ledge 72
and band 60 is devoid of core material for reducing over-
all weight added to the tire and wheel assembly by the
safety insert. Insert 14 is preferably constructed of
two identical semi-circular core segments 71, 73 of
fiber-reinorced synthetic resin material. Core seg-
ments 71, 73 are joined end to end by the bolts 76 and
nuts 78, such that ribs 70 projecting inwardly from
inner band 60 are tightly and non-rotatably clamped
against the outer surface of rim base 18. Notches 80
(FIG. 1) are formed in the edges of inner band 60 for
providing air communication between the tire cavity
proper and the region immediately adjacent sealing
ring 46 and air bleed safety passages 34.
A container or shell 82 (~IGS. 1 and 2) of non-water
base liquid lubricant is mounted in a recess 84 on the
radially outer surface of each core segment 71, 73 in
a position to be engaged and ruptured by the inner surface
20 of tire tread 84 in the event of loss of tire inflation
pressure. At least one lubricant container 82 is mounted
on each core segment, preferably at diametrically opposed
positions for balance. In accordance with an important
~222~6
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feature of the present invention, the radially outwardly facing
surface 86 of ledge 72 is roughened entirely around the ledge
surface as with a multiplicity of microscopic pockets. These
pockets function to retain lubricant at the ledge surface against
the forces exerted thereon by the tire during run flat operation
~hich~70uld other~7ise tend to squeeze the lubricant from bet~een
the engaged tire and core surfaces. In the preferred embodiment
of the invention illustrated in the dra~ings, such microscopic
pockets are formed as a multiplicity of axially oriented splines
88 extending in a circumferential series entirely around the
outer ledge surface. The recesses or channels 89 bet~een splines
88 have a dimension C in the circumferential direction ~7hich
is insufficient to permit complete entry of carcass liner
material 84 ~FIG. 4) during run flat operation so that lubricant
ill be retained therein. A circumferential length L ( FIG. 4)
and depth D of one millimeter on each spline 88, and a
circumferential length C of one millimeter of each recess 89,
are presently preferred. ~lost preferably, the outer edges of
splines 88 are rounded so as to prevent abrasion of the internal
surface of the tire tread. Sucbedgesmay be r~unded ata radius of
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0.25 mm in the preferred embodiment. Thus, in th~
preferred form of the invention illustrated in FIGS.
1, 2 and 4, insert surface 86 comprises a circumferentially
symmetricaly series of crowns and recesses or channels
of equal dimension. Other roughened or irregular sur-
faces are contemplated, including the roughened surface
resulting from sand casting a core constructed of aluminum,
for example.
FIG. 6 illustrates-a modified embodiment of the in-
vention wherein a one-piece safety insert 14a is modified
compared with that illustrated in FIGS. 1-2 and 4 by
elimination of the outer ledge 72 and supporting struts
74. Insert 14a, which includes inner band 60, is thus
adapted during run flat operation to clamp the tire bead
toes 66, 68 firmly against the corresponding bead re-
taining flanges so that the tire will not become dis
assembled from the wheel.
FIG. 6 also illustrates a modified wheel assembly
100 in accordance with the invention as comprising an
inboard rim segment 102 having a band 104 coupled to the
bead seat 106 by the circumferential depression 108.
The outboard rim segment 110 includes a cylindrical hoop
112 received over band 104. The radially and axially
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Z22~86
inner surface 114 of hoop 112 is frustoconical and
sealingly captures an 0-ring 116 in depression 108.
A separate disc 118 is internally welaed to outboard
rim segment 110.
A circumferential array of threaded studs 120 are
internally welded to band 104 and project through
corresponding openings in disc 118. An insert 122 is
telescopically received over each stud 120 and engages
the angulated outboard face of aisc 118 to provide for
flush surface engagement by locknut 54 in a plane per-
pendicular to the stud axis (and wheel axis). The air
bleed channels 34 of FIGS. 3 and 5 are replaced in FIG.
6 by openings or apertures 124 extending radially through
recess 108 outboard of sealing ring 116.
It will thus be appreciated that a wheel assembly
has been provided in accordance with a first important
aspect of the present invention, in particular a mul-
tiple-piece rim assembly. In the embodiments disclosed,
- the wheel assembly includes air bleed passages (34 in
FIGS, 1-5 and 124 in FIG. 6) for preventing inflation
of a tire mounted thereon and/or automatically deflating
a tire mounted thereon when the rim segments are not
properly assembled. Specifically, an 0-ring (46 or 116)
compressed between an inboard edge surface (44 or 114)
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on the demountable rim segment (36 or 110) and the
opposing portion (26 or 108) on the second rim segment
(16 or 102) normally seals the tire cavity. In the
event that such compression is absent because the rim
components are improperly assembled or tightened, or
the compression forces are removed by loosening of the
locknuts 54, the tire cavity is effectively vented to
atmosphere through the air bleed passages.
Although the multiple-piece wheel rim and wheel of
the invention are contemplated as having general utility
in applications such as truck wheels where multiple-
piece wheel rims of other configurations are generally
utilized, it will be recognized that the multiple-piece
rim of the invention has particular utility in combina-
tion with a run flat safety insert which includes a
substantially incompressible portion (60 in FIGS. 1 and
6) for clamping the tire bead toes against the bead re-
taining flanges. This particular utility arises from
the fact that the demountable rim segment 36 in the rim
assembly of the invention need not be positioned axially
inwardly of its final position during the assembly operation
as is the case with many multiple-piece rims of conventlonal
types. Thus, the rim assembly of the invention cooperates
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1222186
with a bead toe-clamping safety insert during the
process of assembling the entire insert tire and wheel
assembly.
Note also that the use of angulated surfaces on
one.or both of the rim segments for engaging the sealing
ring provides accommodation for substantial variation
within manufacturing tolerances on the wheel, insert
, . .
and tire component~. In FIG. 3, the separation at 126
illustrates the point of minimum O-ring compression,
corresponding to a maximum distance between bead flanges
20,40 (FIG. 1). .On the other hand, axial abutment of
rim segments at 128 (FIG. 6) illustrates the point of
minimum spacing between bead flanges.
In accordance with another important aspect of the
present invention, there is provided an improved run
flat safety insert which includes a multiplicity of micro-
scopic pockets or recesses for retaining lubricant at
the engaging insert and tire tread surfaces, and thereby
minimizing the frictional heating which would otherwise
result due to relative circumferential movement between
these two surface The pockets or recesses are of
dimension sufficiently small to prevent filling of the
pockets or recesses by treaa liner material so as to
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displace or squeeze out contained lubricant. The
improved safety insert so provided overcomes problems
noted in prior art inserts of generally similar type
whereby lubricant initially distributed over the tire-
engaging surface of the insert during the run flat mode
of operation is eventually squeezed or forced off of
the insert surface by the forces of the tire tread pressed
thereagainst, so that substantial frictional heating an~
possible destruction and failure of the core and/or tire
may result.
The invention claimed .is:
