Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Backgr~und of the Invention
This invention relates to a wheel for a pneuma~tic
tire and more particularly to a wheel designed to minimize
bead unseating during the use of the tire, especially
in the uninflated state~
Bead retention has always been considered an
important aspect of tire and wheel design. However, with
the advent of run-flat safety tires, tires which are capable
of being driven in the uninflated state for an extended
distance 9 bead retention has become of even greater
importance. When a tire is run in the uninflated state,
there is a strong tendency for the bead portion of the tire
to unseat from the rim of the wheel, which can present
serious hazards to the safety of the occupants of the
vehicle, and/or possibly cause damage to the tire itself.
It is well known to augment bead retention by some
form of projection which extends radially outward from the
bead seat between the tire bead and the wheel well so as to
engage the toe of the bead to restrict axial displacement
of the bead into the wheel well as is exemplified by U.S.
Patent NosO 3,669,174; 2,40~9,666; 1,652,146; 3,664,405;
and German DAS 2,363,175. Due to high cornering forces,
such projections are usually insufficient to retain the
bead in its seat ~hen the tire is run in the uninflated
condition. Additionally 9 projections such as exemplified
in the above patents pose certain difficulties in mounting
and demounting a tire from the wheel, therefore making
automatic mounting and demounting impractical. Furthermore9
the use of a localized projection may cause damage to a
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bead bundle due to stresses imposed upon it during use in
the uninflated condition.
It is also well known to provide a substa~tially
continuous circumferential ridge around the rim as
exemplified in U.S. Patent No. 2,198,978. Safety humps
such as this must of necessity be of relatively low profile
so as not to project radially outwardly substantially
above the surface of the rim seat. Otherwise, the safety
rib would make it too difficult to mount the tire on the
rim seats.
Summary of the Present Invention
A wheel in accordance with the present invention
will allow for automatic tire mounting and demounting ~ -
while providing means for securely maintaining the bead
portion of the tire in its bead seat during use of the
tire both in the inflated and uninflated state.
The invention accordingly comprises a wheel for
supporting a pneumatic tire provided with a pair of
bead portions comprising: a pair of circumferentially
extending flanges in axially spaced-apart relationship;
a pair of rim seats of a first predetermined radius with
respect to the rotational axis of said wheel for seating
said bead portions of said tire, said rim seats merge
from the axially inner ends of said flanges; said wheel
characterized in that at least one rim seat is provided
with an asymmetric hump for engagement with the axially
inner surface of said bead portion adjacent said bead
seat, said asymmetric hump consis-ting a radially extended
portion, said radially extended portion extends about
the circumference of said wheel for at least a portion
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of said circumference at the same axial position on
said wheel, the height of said radially extended
portion starting from one circumferential end of
said radially extending portion proceeding circum-
ferentially about the wheel gradually and continuously
increases to maximum radial height of a second predeter-
mined radius with respect to the axis of rotation of said
wheel then gradually and continuously decreases back to
said first predetermined radius at the other circumferen-
tial end of said radially extended portion.
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Description of the Drawings
Fig. 1 is a cross-sectional plan view of a wheel
according to the present invention.
Fig. 2 is a cross-sectional view of the wheel of
the present invention taken along line 2-2 of Fig. 1.
Fig. 3 is a cross-sectional view of the wheel of
the present invention taken along line 3-3 of Fig. 1.
Fig. 4 is a fragmentary enlarged view of the wheel
of Fig. 1 illustrating the bead portion of a tire mounted
on the wheel and inflated to design inflation pressure.
Fig. 5 is a cross-sectional view of a modified
form of the wheel of the present invention.
Description of the Preferred Embodiment
Referring to Fig. 1, there is illustrated a wheel
10 made in accordance with the present invention. The
wheel 10 comprises a pair of axially spaced flanges 12,
13, extending annularly around the wheel 10. The radially
inner ends of the flanges 12, 13 merge into the axially
outer ends of a pair of bead seats 14, 15, respectively.
The wheel 10 ~urther comprises an annular wheel well
portion 16 spaced axially inward of the bead seats, 14,
15. While the preferred embodiment illustrates wheel 10
with a wheel well portion 16, wheel well portion 16 may be
omitted if desired. Spaced in between wheel well portion
16 and bead seats 14, 15 are asymmetric safety humps 17,
18, respectively, which extend circumferentially completely
about the wheel 10. The asymmetric safety humps 17, 18
are positioned such that when the tire is mounted on a
wheel, as illustrated in Fig. 4, the hump 17, 18 facing
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the tire is adjacent to the toe portion of the tire. For
the purposes of this invention, an asymmetric safety hump
shall be considered a safety hump, which when viewed in a
plane perpendicular to the rotation axis of the wheel, has
a radial extended portion which gradually and continuously
increases from a zero radial height at one end and proceeds
along the circumferential length of the radial extended
portion to a predetermined radial height and subsequently
gradually and continuously decreases back to a zero radial
height at the other end of the portion.
Preferably, as illustrated in Figs. 1 and 4, the
contour of the radially outermost surface of safety humps
17, 18 is convex as viewed in a cross-section from a plane
containing the rotational axis of the wheel. Having such
a contour facilitates the ease of tire mounting.
Referring to Figs. 2 and ~, asymmetric safety humps
17, 18 are provided with radial extended portions 20, 22.
As can be seen from the drawings, each radial extended
portion 20, 22, when viewed in a plane extending
perpendicularly to the rota-tional axis of the wheel 10, has
a height, as measured radially of said axis, which is at one
end of the portion at zero value and whi¢h, from said one
end, increases continuously and gradually to a predetermined
height and subsequently decreases continuously and gradually
back to zero value at the other end of the portion. For
the purpose of this invention, in all embodiments thereof,
-the term "gradually" means tha-t the increase in height
takes place over a circumferential length equivalent to an
angle of at least ten degrees about the rotational axis of
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the wheel. Preferably the maximum radial height of each
portion 20 7 22 occurs midway between its ends. The
remaining portions 19, 21 of safety humps 17, 18 have a
constant radial height which generally does not extend
beyond the height of standard safety humps presently known
in the tire and wheel industry. In the emdobiment illus-
trated, radial extended portions 20, 22~ extend a circum-
ferential distance about wheel 10 of at least 140,
generally in the range of 140 to 200, preferably 180.
For the purpose of this invention, the radial height of
radial extended portions 20, 22 is the distance be-tween
the radially outermost portion 20, 22 and the radial
distance of portions 19, 21 at that point as shown with
dotted lines in Figs. 2 and 3. The radial extended
portions 20, 22 may be placed congruently or as desired;
preferably they are positioned at 180 from each other as
illustrated in Figs. 2 and 3. The dotted line shown in
Figs. 2 and 3 illustrates the path in which safety humps
17, 18 would have taken if it were not for radial extended
portions 20,22.
In the preferred embodiment, radial extended
portions 20,22 are shown as one continuous radial extended
portion; however, portions 20,22 may be constituted of a
plurality of spaced projections, the radial height of which
would follow the same path as continuous portions 20,22
illustrated in Figs. 2 and 3; that is, the radial height
- of each of the plurality of projections would start at a
zero value at one end of the portion 20,22 and gradually
increase to a maximum predetermined radial height and -
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subsequently decrease back to a zero radial height at the
other end of portions 20, 22.
Referring to Fig. 4, each radial extended portion
20, 22 at its poin-t of maximum radial height extends
radially outward from the nominal rim diameter NRD a
distance H equal to at least the distance W. The distance
W being the radial distance from the nominal rim diameter
to the radially innermost point of the bead core of a tire
which is mounted on the wheel 10 and is inflated to design
inflation pressure. For the purpose of this invention,
the nominal rim diameter NRD is defined as a line parallel
to the rotational axis of the tire and tangent to the bead
heel of the wheel. Radial extended portions 20, 22 at
their point of maximum radial height H as measured from the
nominal rim diameter NRD, may extend radially outward a
maximum distance equal to about one-half of the flange
height B.
Fig. 5 illustrates a modified form of the present
invention. The wheel 100 illustrated in Fig~ 5 is similar
to the wheel 10 illustrated in Figs. 1 through 4, like
numerals representing identical par-ts. The wheel 100 is
different from wheel 10 in that portions 19, 21 of safety
humps 17, 18 are omitted. Radial extensions 120 and 122
are similar to radial extended portions 20, 22 of Figs. 1
through 4) except that the ends of radial extensions 120,
122 start at a zero height from the axially outward bead
seats 14, I5 whereby continously and gradually increasing in
height to the same limits previously discussed with
respect to radially extended portions 20, 22. -
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The extensions 120, 122 extend circumferentially about the
wheel within limits previously discussed with respect to
portions 20, 22 of safet~ humps 17, 18.
A wheel made in accordance with the present inven-
tion allows for easy manual or automatic mounting of the
tire on the wheel and will minimize any injurious effects
to the bead portion of the tire, and will minimize the risk
of bead unseating during running of the tire both in its
inflated and unin~lated state.
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