Note: Descriptions are shown in the official language in which they were submitted.
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VI:~IICLE WHEEL FOR A PNEUMATIC TI~E
Bac~ground o~ the Invention
The present invention relates to a vehicle
wheel having a rigid rim on which can be mounted a
pneur,latic vehicle ~ire of rubber or rubber like
synthetic material; the tire has a carcass which is
anchored in ~eads by means of pull resistant and/or
compression resistant bead cores; the rim is provided
laterally outwardly with rim flanges, and next to
these sea~ing surfaces for the tire beads; on the
radially outer side, the rim is provided with emergency
operation support suraces for the inner wall o~ the
tire.
A vehicle wheel of this general type, according
to which the rim flanges extend radially inwardly,
and the tire beads are disposed on ths radially inner
periphery of the ri~, has already been proposed. In
addition to being suitable for a nonmal driving oper-
ation with an inflated tire, it is also suitable for
a so-called emergency operation, according to which,
after the air has escaped from a damaged tire, the
tire can still be drive~ a considerable distance with-
out undergoing permanent damage. This is primarily
achieved by the fact that the radially outer side of
rim is provided with support surfaces for supporting
the tire, and that the tire can bulge laterally
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outwardly, so that during an emergency operation
the side wall portions do not contact the roadway.
With vehicle wheels of the aforementioned
general type having relatively large diameters of the
rim support surfaces, difficulties can arise during
mounting of the tire because one of the tire beads
must be brought into the vicinity of one of the rim
flanges, i.e. one of the two tire beads must overcome
the central region of the rimO This problem is all
the more critical since the wheels of the aforemen-
tioned general type have a rim which has no drop
center on the radially outer side, so that it is im-
possible to introduce a tire bead in the customary
manner into a drop center for overcoming the central
rim portion.
It is therefore an object of the present in-
vention ~o provide a vehicle wheel of ~he aforemen-
tioned general type in such a way that the tire can
be reliably mounted on a one-piece rim which is pro-
vided wi~h support surfaces ~or the tire.
Brief Description of he Drawings
This object, and other objects and advantages ofthe presen~ inven~ion, will appear more clearly from
the following specification in conjunction with the
accompanying drawings, in which:
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Figure 1 schematically illustrates a
tire having side walls which extend to the sides,
and a rim which is partially introduced into the
tire;
Figure 2 schematically illustrates a
tire having side walls and beads which are curved
inwardly, and a rirn which is partially introduced
into the tire;
Figure 3 is a plan view of a tire and
rim in the position of Fig. l;
FigurP 4 is a radial partial section of
one inventive embodiment of a wheel showing a com-
pletely moun~ed tire;
Figure 5 is a partial radial section of
a rim; and indicates a contour curve and an associated
oval inner circumferential bead curve; and
Figure 6 shows a second inventive rim
embodiment with its contour curve and associa~ed
inner peripheral bead curve.
Summary of the Invention
By one aspect of thls in~ention, th~re is pro-
vided a vehicle wheel on which can be mounted a
pneumatic vehicle tire which is made of rubber or
rubber-like syn~hetic material, and which has a car-
cass which is anchored in beads by means o pull re-
-sistant and/or compression resistant bead cores;
said wheel has a rigid rim which is provided laterally,
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i.e. axially, outwardly wi~h respective rim flan~es;
next to and axially inwardly of each rim flange is a
respective seating surface for said tire beads; the
radially outer side of said rim is provided with an
emergency operation support surface ~or the inner
wall of said tire; the improvement wherein, for
permitting mounting of said tire on said rim by a
r~lative movement of said rim and tire toward one an-
other at essentially right angles to one another, and
by a su~sequent rotation o~ said rim relative to
the interior of said tire, that rim contour curve
which extends ~hrough the axis of rotation of said
rim has a circumferential lengt~ which corresponds at
most to 0.96 times the radially inner circumferential
length of said tire in the bead region in the mounting
state.
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Within the framework of this application, rim
contour curve or characteristic refers to a curve
which a string assumes which is placed tightly about
the rim at right angles to the circumferential
direction of the rim and at the greatest diameter
thereof. Furthermore, inner circumference of the bead
refers to the circumference of the tire in the region
of the bead at the location of the smallest diameter
(the inner diameter o the bead) in the mounting state
of the tire bead.
Pursuan~ to the present invention, mounting of
the tîre is considerably sirnpliied as pertai~s to the
introduction of a one-pieee rim into the interior of
a tire. An additional simplificatlon in the sense of
less exertion of force is achieved by bringing one
bead region of the tire into its oval shape by means
of external forces already prior to introduction of
the rim into the interior of the tire.
As a result o the dimensioning prPscribed pur-
suant to the present inven~ion, it is possible, whileassuring the moun~ability o the tire, to optimally
configure the axial and radial dimensions of the rim
support surface, so that tha emergency operating
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properties of the wheel can also be improved consider-
ably. ~urthermore, pursuan~ to the prescribed dimen-
sioning, ~he diameter difference of the rim in the
vicinity of the rim flanges and the support surfaces
can be optimiæed, so that on the one hand the rim
flanges do not have to be unnecessarily high, but
on the other hand there is assured that the bead
cores Pnter suficiently deep behind, i.e. inwardly of,
the rim flanges to reliably assure that they are not
released.
The presPnt invention is applicable not or,ly
for vehicle wheels whe~e the tires are mounted radial-
ly inwardly on the rim, but also where the tire beads
are disposed radially ou~ardly on the rim.
To mount t~e tire, the rim and tire are not
guided into one another in such a way that their
axes of rotation are parallel ~o one another, but
rather are guided in such a position that the axes of
rotation form a rela~ively large angle, preferably
approximately 90.
Pursuant to specific eatures of the present
invention, the rim flanges may extend essentially
radially inwardly, and the seating surfaces for the
tire beads may be disposed on the radially inner
side of the rim next to the rim flanges.
The ratio of ~he height of the ~ire to the
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width oE the tire may be less than 0.65.
The maximum supporting surface diameter of
the rim in the vicinity o ~he support surface may
be about 35mm greater than the nominal diameter
of the rim.
The rim flanges may also extend essentially
radially outwardly, and the seating surfaces for
the tire beads may be disposed on ~he radially
outer side of the rim.
The supporting surEace diameter o the rim in
the vieinity of the support surfaces may correspond
approximately to 1.18 times the inner diameter o the
bead.
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1~escription oE PreEerred ~mbodiments
R~ferring now to the drawings in detail,
Fig. l shows a tire and wheel assembly with a
one-piece rigid wheel rim l, and a tire 2 having
beads 3 which are syaced very far apart.
In the vulcanizing position, the axial dis-
tance corres1)onds approximately to twice the wi~th
of the tread surface. ~ead cores 4, which can be
pull-resistant and/or resistant to compression, are
dispose~l in the two bea~s 3. If necessary, the
beads 3 can be designed to be pivotable about the
bead cores 4, This is partieularly necessary when
the side walls are relatively short.
In the tire 2 of Fig. 2, the side walls 5 and the
beads 3 are curved inwardly, and the tire 2 is also
mounted in this state.
To moun~ the tire on the rim, the axis of ro-
tation of the rim 1, as s'nown in Figs, l and 2, is
preferably r~oved toward the tire 2 in such a ~vay
that it is at right angles to the axis of rotation of
~he tire 2; the rim l is then introducPd into ~he
interior of t~e tire 2. It can be expedient for a
mechanical mounting to deviate from the perpendicular
pOSitiOtl of ~he two axes of rotation. Synonymous
with moving the rim l is a movement of the tire 2 or
a movement of both the rim an~ the tire, since the
impor~ant thing is the relative movement of tlle two.
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~hen the rim 1 is introduced into the tire 2, the
bead region o~ the tire is distor~ed into an oval,
~ h ~he len~th oE the inner periphery of the bead
I~U beinp,~naintained. The introduc~ion of the ri-rl 1
is ~articularly simple and protective of the tire if
the distortion o the tire is already accomplished
by external forces prior to the introduction of the
rim 1, for exalrlple by ixing the tire by means of
a holding device. The o~al distortion o~ the tire 2
in its ~ead region is particularly clearly illustrated
in Fig. 3, which is a plan view of the tire 2 ar,~ rim
1 of Fig. 1 The greatest diameter of the rirn 1 ic
also the maximum supporting surface diameter DST.
IJ~len the ~reatest diameter DST o the rim 1 has
reached the interior of the tire, it is turne~ until
its axis of rotation extends parallel to the axis of
rotation of the tire 2. The further steps for mount-
in~ the ~ire, i.e. overcoming the rim flanges ~ (Fi~
4) with t~lC aid of recessed mounting portions 7 (deep
bed), and the placemen~ of the ~ire beads 3 on the rim
seatinr surfaces 8, is accornplished in a known manner,
and is described, for example~ in Gennan Offenlegun~s-
schrift 30 00 4~8.
Iiig. 4 shous the tire mounted on a one-piece rim
1, which is provided with radially inwardly extending
rim flanges 6, next to these on the radially inner side
of the rim 1 seating surfaces 3 for the tire 2, next
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to tllese rece3sed mounting portions 7, and on the
ra~iall~- outer side a circumferential support sur~ace
9 for .he tire 2.
In order on the one hand to assure that the tire
2 can be mounted, and on the other hand to be abl~ to
optimally select the radial and axial dimen~ions of
the rim suppor~ surfaces 9, a certain correlation of
the inner periphery or circumference ~U of the tire
bead to the length of the rim contour curve or charac-
teristic ~ (Fig. 5) is necessary. First of all, it isreadily discernible that a theoretical limit is that
the rim con~our curve H can never be longer than the
inner circumference 1~ of the tire bead. The length
of the rim contour curve 1~, however, i~ediately in-
cludes the maximum supporting surface diameter DST and
the span of the riul. On the other hand, a limit is
given in that the center-to.-center diameter of the
core rings (the dianeter of the bead cores 4, measured
from one cross sectional center point to the other
cross sectional center point) should correspond
approximately to the diameter formed by the rim flanges,
so that the bead cores extend suf~iciently far behind
or inwar~ly of the rim flanges 6 that they are reliably
kept from being released. In tests with passenger
vehicle tires, pull resistant and compression resistant
.. cable cores having a cross-sectional diameter of about
7mm were used.
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I'ig. 5 schematically illustrates the geor,le~ric
relationship bctween a tire having ~he dimensions
200/45 r~ 4so and a rim havin~, the dimensiotls 135 x 450,
~xtensive practical tests in the areas of driving
properties and emer~ency operation properties for the
passenger vehicle wheel showed that for a tire having
these dimensions, the optimum supporting surEace
diameter DST was 485~m, i.e. a diar.leter wllich was
35mm grcater than the nominal diameter ~, which was
450mm~
To determine the 1 ngth of the rim contour curve
H, helping points Al, A2 can be marked on the outer
sides at the widest spots of the rim 1 (namely the
span or inner width plus two times the thickness of the
walls), so that the contour curve H comprises twice
the diameter DA plus twice the arc len~th Al A2, with
arc len~th referring to a curve formed by a strin" or
other filament which stretches between Al and A2. If
DA = 440mm, then the length of the contour curve II =
2 x 440 ~ 2 x 170 = 1220mm.
To simplify the aDalysis, and without tampering
with the results, the calculation can be made with the
nominal ~iameter> along with appropria~e correction of
the arc length, as follows:
~1 = 2 x 450 + 2 x 160 = 1220mm.
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The inner circumference of the bead I~U of the
tire which was used wa5 1303mm (inner beacl diameter
was 415~n), so tha~ a value of 0,936 resulted for the
ratio oE the circumferenti~l length of the rim
contour curve to the inner circurll~erence of the bead.
The following Table 1 lists the results of tests
which examine the possibility of mountin three tires
of the sizes 200/~5 R 400, 200/45 R ~25, and 200/~5
~ 450 on rims having nominal diameters of 400, 425,
and ~50 and various spans. ~11 of the rims had a
supportin~ surface diar.leter DST which was 35mm greater
than the ~ominal diameter DN, In the last column,
"r.lountable span", the value in parentheses indicates
that at the correspondin~ span, the tire could not be
mounted or could only be mounted with the danger of
damaging the tire, so that the value which appears
directly thereabove is the maxim~n span. The sur-
prising result which can be gathered fo~n the nex~ to
: the last column is that for all of the tested tlres
and:rims, a mountability of ~he tlre results when the
ratio of the rim contour curve H to the inner bead
:
periphery IIU is less than or equal to 0.96.
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In Table 2, the ratio of the supportirlg surace
diameter to the inner bead diameter was determined
for all three tested ~lre/rim p,airs; an average
value oE 1.18 resulted.
T A ~ L E 2
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Nominal Supporting surface inner diameter Ratlo of DST
diame~er diameter of the beadto inner
D~ tmm~ DST ~ DN (mm) bead dlameter
~ 35 (mm)
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450 485 415 1.17
425 460 390 l~ls
400 435 365 1.19
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Fig. 6 illustrates the mountability of a tire
on a suppor~ing surface rlm which has the ~eating
surfaces 8 for the tire beads on tha radially outer
side nex~ to the rim flanges 6. Firs~ of all, the
rim is again introduced into the interior of the tire
at nearly right angles there~ in ~he manner previous-
ly describ~d. ~ In order for this to even be possible~
the ratio of the length of the r1m contour curve to
the inner periphery of the tire bead mus again be
less than or equal to 0.96. The results of Table~2
are relied upon for the construction of the rim sup- :
port surface 9, so that ~he maximum suppor~ing surface
diameter DST should correspond to approximately~
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1.18 times the inner bead diameter o the tire.
After the greatest diameter of the rLm is com-
pletely disposed within the tire, it i8 rotated until
the axes of rotation of the tlre and the rim extend
parallel to one anothér. The ti.re beads are now
disposed laterally outwardly next to the rim flanges
6, and mounting of the tire is completed in the cus-
tomary manner with the aid o~ the two drop centers
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The present invention is, of course, in no way
restricted to the specific disclosure of the specifi-
cation, tables, and drawings, but also encompasses
any modifications within the scope of the appended
claims.
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