Run - flat tire

In a pneumatic, tired wheel having a tubeless tire mounted on the rim of the wheel, the improvement comprising a toroidal support device to enable the tired wheel to travel in a flat state. The support device comprises an inflatable, toroidal, inner tube located on the rim for elastically clamping the tire beads against the rim flanges, said tube radially extending from the well of the rim to or slightly beyond the radially outer edges of the rim flanges, and a toroidal support element whose radially internal, circumferential wall section is impervious to puncture and lies adjacent the radially external, circumferential area of the inner tube, and wherein the outer surface area of the support element is spaced from the inner surface area of the tire when the tire is in its inflated state so that under normal travel conditions the support element does not contact the inner surface area of the tire. The foregoing abstract is neither intended to define the invention disclosed in the specification, nor is it intended to limit the scope of the invention in any way.

BACKGROUND OF THE INVENTION 
The invention relates to vehicle pneumatic tires and more particularly to a 
vehicle pneumatic tire with properties for travel in the flat state, 
wherein a toroidal support device is arranged on the inside of a tubeless 
tire mounted on a rim. 
Efforts have been under way for a long time to design a vehicle pneumatic 
tire which is puncture-proof and self-sealing in order to obtain a 
run-flat tire. For this purpose, it is known to fill out the pneumatic 
vehicle tire following manufacture with foam material (cf. German 
Disclosures Nos. 19 36 526, 15 05 029, 16 05 664). Upon occurrence of a 
puncture, the inner area in the tread zone comes to apply against the area 
in proximity of the beads of the tire. Thereby occurs a substantial 
fulling activity and, in the case of a vehicle continuing to travel under 
load, a marked friction between the inner areas of the tire, which 
phenomena results in rapid destruction of the tire. Moreover, there exists 
the risk that, as a result of the fulling under load, the tire beads may 
detach from their fixed seat on the rim so that the tire separates from 
the rim. In any event, in the case of a flat tire, ability to properly 
steer the vehicle is lost. 
Complete filling of the tire with foamed material results in a tire 
offering a substantially poorer travel comfort. Therefore, tires 
foam-filled in this manner are suitable only for vehicles intended for 
special applications, such as vehicles designed for emergency use in 
natural catastrophes, for bulletproof tires, or the like. To this factor 
one must add that the pressure brought about by the filling with foam 
material is reduced with time as a result of diffusion or other factors. 
In order to prevent the separating of the beads from their fixed seat on 
the rim, it is furthermore known in the art to arrange a toroidal support 
device at the bottom of the rim which fills the remaining free space 
within the cross-section of the rim and the beads supported thereupon and 
clamps the beads rigidly or elastically against their seat areas on the 
rim. As a result, detachment of the beads from the rim during travel in 
the flat condition is prevented. Moreover, the toroidal support device 
whose radially external circumferential area is situated substantially at 
the level of the radially outer edges of the rim flanges or extends only 
slightly therebeyond offers an additional support area for the central 
zone of the tread section of the tire upon travel in the flat state (cf. 
German Disclosure No. 23 39 516 or U.S. Pat. No. 4,059,138). 
In the case of another support device for run-flat tires, the toroidal 
support body projects cross-sectionally substantially beyond the maximum 
diameter of the rim flanges radially outwardly and far into the interior 
of the inflated tire. The radially internal foot section of the support 
body situated in the rim area has a reinforced section situated at the 
level of the tire beads forcing the beads against the seat areas in the 
rim. The section of the support body projecting therebeyond and connected 
therewith as a one-piece element is designed in the shape of a torus and 
has a substantially circular cross-section whereby, upon the use of the 
pneumatic tire, there remains between the inner surface of the inflated 
tire and the outer surface of the toroidal support body a sickle-shaped 
clearance which, with its cross-sectional edges, extends down into the 
bead area. Owing to this design, the friction between the support body and 
the tire is substantially reduced in normal operation. The toroidal 
support body consists of a rubbery material having closed and pressurized 
gas or air cells. On the inside of the toroidal support body there can 
also be provided an air chamber inflatable by means of a separate valve 
from the outside. In any event, the air chambers and cells of the support 
body are sealed with respect to the cross-sectionally annular space 
between the support body and the tire. As a result of the inflation 
pressure of the tire, the cross-section of the support body comes to be 
compressed whereas, upon the flattening of the tire, the support body 
comes to expand cross-sectionally as a result of the internal pressure in 
the cells or air chambers (cf. French Pat. No. 1,390,440). 
SUMMARY OF THE INVENTION 
Based on the run-flat tires of the last-mentioned type, it is the object of 
the instant invention to improve such a tire so that, even under extreme 
conditions, said tire will still exhibit satisfactory travel properties in 
the flat state, without an excessive increase in the weight of the tire 
for normal operation and without any imbalance or vibration. At the same 
time, there is also provided simplicity of mounting, even on a 
single-piece rim and prevention of any damage to the pressurized portion 
of the support device as a result of foreign elements causing flattening 
of the tire. Finally, any friction between the tire and the support device 
during normal operation is avoided. 
The aforementioned objects are achieved in accordance with the instant 
invention which provides an improvement in a pneumatic, tired wheel having 
a tubeless tire mounted on the rim of the wheel, the improvement 
comprising a toroidal support device to enable the tired wheel to travel 
in a flat state. The support device comprises an inflatable, toroidal, 
inner tube located in the rim for elastically clamping the tire beads 
against the rim flanges, said tube radially extending from the well of the 
rim to or slightly beyond the radially outer edges of the rim flanges, and 
a toroidal support element whose radially internal circumferential wall 
section is impervious to puncture and lies adjacent the radially external, 
circumferential area of the inner tube, and wherein the outer surface area 
of the support element is spaced from the inner surface area of the tire 
when the tire is in its inflated state so that under normal travel 
conditions the support element does not contact the inner surface area of 
the tire.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
One embodiment of the inventive support device is shown in FIGS. 1 and 2, 
wherein there is seen a tire 1 having a tread 2 fixedly mounted with its 
bead areas 4 on the corresponding seat areas of a wheel rim 3. The rim 3 
has shoulders 5 and flanges 6 that constitute an angle-shaped seating area 
for the beads. 
In the well 7 of the rim 3 there is inserted the first portion of the 
support device, to wit, an inner tube 8 constituting an inherently closed 
air chamber externally inflatable via a separate valve 8a. The inner tube 
8 can be made from relatively thin rubber material which, if necessary, 
can be reinforced by a fabric ply or the like. In its inflated state, the 
inner tube 8 may have a circular, oval, or even a profiled cross section. 
The inner tube 8 is designed to fill out the well 7 of the rim 3 and, in 
its operating state, illustrated in FIG. 1, to press against the inside of 
the bead areas 4 and, in this way, force the beads against their seating 
areas on the rim 3. 
The second portion of the support device is a toroidal support element 9 
having a torus-like cross section similar to that of the tire 1 itself, 
but being of a reduced cross-sectional area so that there remains between 
the support element 9 and the inside of the tire 1 a sickle-shaped space 
when the tire pressure is normal. The support device shown in FIG. 1 is 
preferably made in such a way that the support element 9 will not contact 
the inner area of the tire 1 at any point during normal operation so that 
no friction can occur between these two bodies. 
The support element 9 has a radially internal, circumferential wall section 
12, defining in the mounted, operating condition, the contact plane 10 
between the inner tube 11 and the support element 9. The diameter 18 of 
the contact or support plane 10 is at least equal to and preferably 
somewhat larger than the maximum diameter of the flanges 6 of the rim 3. 
The wall section 12 is circumferentially inextensible and consists of a 
material that cannot be punctured. For this purpose the entire toroidal 
support element 9 preferably consists of one piece of sheet metal, or a 
correspondingly rigid plastic material, or a hard rubber compound. 
As seen in FIG. 2, the two sidewall sections of the support element 9 
emanating from the wall section 12 are designed in the form of a comb and 
comprise reciprocal, circumferentially spaced, strip-like prongs 13 and 14 
which are bent to define the contour of the support element 9 and mate 
with one another in the area 15 so that they circumferentially mutually 
support one another and permit bending into one another substantially in 
the position shown by the dotted lines in FIG. 1 when the support element 
9 is subjected to loads which occur when the tire 1 loses its internal 
pressure and rests with its inner surface on the support element 9 in the 
area of the tread 2. The sidewall sections have adequate elasticity and 
rigidity properties in order to reliably and elastically absorb, upon 
travel of the tire in the flat state, the load to be borne by the tire. 
Upon flattening of the vehicle pneumatic tire 1, the wall section 12 
completely covers the radially external circumferential area of the inner 
tube 8 and protects same against any attack from the outside by mechanical 
means as well as against any fulling during travel in the flat state. As a 
result, it is possible to travel extensive distances with a flat tire. 
FIGS. 3 and 4 illustrate two additional embodiments of the support device 
in which the design and arrangement of the inner tube 8 as well as its 
function remain unchanged. The embodiments of FIGS. 3 and 4 differ from 
that of FIG. 2 only by a different design of the outer toroidal support 
element of the support device. 
In the case of the embodiment of FIG. 3, the support element 25 is made up 
of a radially internal belt 26 reinforced by ropes, wires, filaments, or 
cords 28 and a torus-like body 29 of circular cross section joined thereto 
in a single piece and preferably made from foam material with opened or 
closed cells, solid rubber, or a plastic material. The radially internal, 
tape-like, nonextensible and punctureproof belt 26 defines with its inner 
circumferential area 27 the diameter 18 of the contact plane 10 according 
to FIG. 1. The diameter of the central opening enclosed by the area 27 is 
at least equal to the maximum diameter of the rim flange 6. 
The resilience of the toroidal body 29 can be increased by recesses or bore 
30 running substantially parallel to the axis of the body 29. The 
resilience and rigidity of the toroidal body 29 determine the 
load-carrying capacity of the support element 25 in FIG. 3. As a result of 
the inflated tube 8, the support element 25 is firmly tensioned over the 
rim 3 and is therefore capable of transfering the necessary lateral and 
steering forces. 
The toroidal support element 35 illustrated in FIG. 4 is one which may be 
manufactured in an especially simple and inexpensive manner. The support 
element 35 is an inherently closed, endless, toroidal body that, 
prefabricated in this form, can be pushed onto the rim 3 according to the 
assembly instructions described below in greater detail, following 
mounting of the inner tube 8 on the rim and moderately inflating same. 
The toroidal support element 35 has a radially internal, axially extending 
wall 36 which, cross-sectionally may be slightly curved to the outside. 
The lower side 38 of this wall 36 defines the contact plane 10 between the 
support element 35 and the inner tube 8. The minimum inside diameter 49 of 
the support element 35 is therefore at least equal to the maximum diameter 
18 of the rim flanges 6. For the purpose of stiffening the inner wall 36, 
same can be reinforced with an insert 37, which preferably is 
nonextensible and protects the wall 36 against puncture. The axial width 
of the wall 36, suggested by the twin arrow 44, is such that the edges of 
the support element 35, during normal operation of the pneumatic tire 1, 
have virtually no contact with the inner area of the tire 1, but, upon a 
drop in pressure inside the tire 1, the axial width 44 is adequate to 
protect the radially internally situated inner tube 8 against puncture or 
other effects by mechanical forces upon travel in the flat state. 
Extending from the lateral edges of the wall 36 are two sidewall sections 
40 and 41 which, cross-sectionally, have an angular profile and are convex 
with respect to one another. The points 42 of maximum closeness of the 
sidewall sections 40 and 41, suggested by the arrow 39, are radially 
spaced from the wall 36. In the area of maximum closeness at points 42, 
the sidewall sections 40 and 41 exhibit a substantial wall thickness that 
is considerably greater than and preferably a multiple of the thickness of 
the wall 36. Beginning with the points 42 of maximum closeness, the 
thickness of the sidewall sections 40 and 41 decreases, preferably 
steadily, radially outwardly and radially inwardly substantially down to 
the thickness of the wall 36. The reciprocal spacing of the two sidewall 
sections 40 and 41 at their radially outwardmost ends is, as indicated by 
the plane 43, substantially greater than in the area of the wall 36. Said 
outwardmost ends are connected by a radially external, axially extending 
wall 45 substantially parallel to the radially internal, axially extending 
wall 36 and of about the same thickness as the wall 36, thereby producing, 
in cross-section, a closed toroidal support element 35 made from one 
material. This support element 35 is dimensioned such that the sidewall 
sections 40 and 41 are capable of yielding elastically in the direction of 
the arrows 50 and the arrows F and possess sufficient rigidity to absorb 
the load during travel of the tire 1 in the flat state. 
The distance 46 from the support element 35 to the inner area 53 of the 
tire 1 in its crown, under standard operating conditions, preferably is at 
least 15 to 40 mm in order to assure that there will be no contact between 
the tire 1 and support element 35 in the event that the tire pressure 
drops slightly below standard pressure. This spacing distance applies to 
any of the support elements which may be used. 
As far as operation is concerned, an internal overpressure of the support 
element 35 is not essential. Apertures 60 may be employed in the support 
element 35, said apertures 60 preferably being located in the radially 
external wall 45, in order to assure equal pressure within and without the 
support element 35. 
The support element 35 consists preferably of a rectilinear, extruded, 
profiled element that, following cutting to its length, is developed, to 
form with its extremities, one single piece of an inherently closed 
toroidal element. 
The novel supporting device disclosed herein can be readily and reliably 
mounted, even onto a one-piece rim. For this purpose, all that is 
necessary is first to push one bead of the vehicle pneumatic tire in the 
customary manner on the rim, whereupon one inserts the inner tube of the 
support device that is thereupon moderately inflated. In spite of its 
essentially nonextensible, radial inner segment, the outer support element 
can then be pushed onto the moderately inflated tube. Then, the second 
bead of the vehicle pneumatic tire is mounted onto the rim. The tire and 
inner tube of the support device are then inflated independently. 
The inflated inner tube of the support device assures that the tire beads 
seat firmly against the rim and endows the support device with adequate 
elasticity for travel in case of a flat tire. The inner tube of the 
support device is, upon use, limited essentially to the unoccupied 
cross-sectional area of the rim and does not, even upon flattening of the 
tire, extend significantly beyond this cross-sectional area in view of the 
fact that the inner tube is virtually enclosed by the rim, the bead areas, 
and the circumferentially nonextensible inner area of the support element. 
The radially internal, circumferential wall section of the support 
element, upon travel with a flat tire, protectively covers the outer 
circumference of the inner tube and secures same against any damage by 
foreign elements, such as nails or the like that may have punctured the 
pneumatic tire and caused its flattening. As a result, the inner tube of 
the support device will perform its function even during extensive travel 
in the flat state. 
Under normal conditions, the support element does not contact the inner 
area of the vehicle pneumatic tire so that no friction can occur between 
the two parts. The centering of the support element within the tire is 
brought about through the firm application of the radially internal, 
circumferential wall section of the support element against the outer 
circumferential area of the inner tube. In view of the fact that both the 
inner tube and the support element can be designed respectively as hollow 
bodies, the entire support device has a relatively light weight. 
Various modifications and changes are contemplated and may obviously be 
resorted to, without departing from the spirit or scope of the invention 
as hereinafter defined by the appended claims.