Tire and rim assembly with dispensing means mounted in a balanced array

A tire and rim assembly with a plurality of dispensing means adapted to release material into the inflation cavity upon operation of the assembly with the tire in the deflated condition to, for example, minimize damage to the tire cause by operation after deflation. The dispensing means are mounted in a balanced array so that each dispensing means lies at least partially in the well of the drop-center rim, and the dispensing means define a clear arc in the well which is adapted to receive portions of the beads during mounting of the tire to the rim. The clear arc of the well may also receive the beads of the tire during demounting of the tire from the rim assembly. Thus, the tire may be mounted to or demounted from the rim assembly by a method which incorporates the ordinary "buttonhooking" procedure commonly utilized with drop-center rims.

BACKGROUND OF THE INVENTION 
This invention relates to pneumatic tire and wheel rim assemblies, and more 
particularly to pneumatic tire and wheel rim assemblies which are capable 
of continued operation even after accidental deflation of the tire or of 
reducing the deleterious effects of such deflation. 
If an ordinary tire is deflated and continued operation is attempted, the 
interior surfaces of the flattened tire will rub against one another and 
generate a great amount of heat which leads to rapid destruction of the 
tire. Tire engineers have long known that this destruction can be 
prevented or at least postponed significantly if, for example, a lubricant 
is present within the so-called "inflation cavity" of the tire and rim 
assembly (the space bounded by the tire and the rim). The lubricant 
reduces the amount of friction between the interior surfaces of the tire. 
A great number of effective lubricants are known to those skilled in the 
art, including water, oils, alcohols, and silicones. 
Also, material desired to be placed within the inflation cavity may include 
a puncture sealant composition, and it may also include chemicals which, 
when mixed together, generate a gas to at least partially reinflate the 
tire. Such puncture sealant compositions and chemicals which react to 
produce gas when mixed are well known to those skilled in the art. 
The particular composition and/or chemicals to be placed within the 
inflation cavity of the tire and rim assembly is a matter of choice, 
dependent upon the desired properties and mode of action of such materials 
or combinations thereof. The term "material" will be used in this 
disclosure as a generic term embracing all composition and chemicals or 
combinations of same which may be desirably placed into the inflation 
cavity of a tire for release upon deflation of the tire. 
Although the material can be simply placed within the inflation cavity of 
the tire and rim assembly when the tire is mounted to the rim, such 
placement is subject to several disadvantages. First, more volatile 
components of the material may permeate and diffuse out through the walls 
of the tire. Second, while the assembly is standing still, the material 
may settle to one or more spots on the circumference of the tire. The 
concentrated masses of the material at such spots would throw the entire 
assembly out of balance. Finally, materials intended to react in a desired 
fashion only upon deflation could, of course, react prematurely and 
undesirably if simply placed into the inflation cavity. 
To overcome these disadvantages, it has been proposed to enclose 
material(s) in dispensing means mounted to the tire and rim assembly. The 
dispensing means enclose material(s) during normal operation of the tire 
but release same into the inflation cavity upon operation of the assembly 
with the tire in a deflated condition. If, for example, chemicals which 
react together are used, each of the components of the mixture may be 
contained in a separate dispensing means so that the components are mixed 
together when all of them are discharged into the inflation cavity upon 
deflation of the tire. While the use of such dispensing means provides an 
effective solution to the aforesaid problems, it creates a new problem: 
where to place the dispensing means so that they do not interfere with 
mounting of the tire on the rim. 
This problem can best be understood in light of some description of the 
ordinary wheel rim and tire and the procedure used for mounting the tire 
on the rim. The ordinary passenger car wheel rim is a so-called 
"drop-center" rim. It includes a pair of radially extensive flanges at its 
axial extremities, a pair of axially extensive bead seats which are 
generally cylindrical and which are located between the aforesaid flanges, 
and a drop center portion located between the bead seats. The drop center 
is so called because it defines a "drop" or radially inwardly extending 
well between the bead seats. The conventional tire which is mounted on 
such a rim includes a pair of beads at the radially inwardmost portions of 
its sidewalls. These beads, which are usually reinforced with steel wire, 
are flexible but substantially inextensible, and have an inner diameter 
equal to the diameter of the bead seats. Since the diameter of the beads 
is less than the diameter of the flanges, it is impossible to simply slide 
the tire onto the rim until the beads lie on the bead seats. 
Instead, a so-called "buttonhooking" procedure must be used. A portion of 
each bead of the tire is placed into the drop-center well. Because the 
drop-center well extends radially inwardly, the portions of the beads 
lying therein are close to the center of the wheel rim. Therefore, the 
opposite portions of the beads extend beyond the flanges, and can be pried 
over one flange. 
This "buttonhooking" procedure is the most common procedure for mounting 
passenger car and light truck tires. Every service station attendant is 
familiar with this procedure and automobile manufacturers have expended 
substantial sums in developing automated equipment for performing it. 
Therefore, any change in the wheel rim assembly which would require a 
substantial change in tire mounting procedure would be highly undesirable. 
If the drop-center well were completely occupied and filled by the material 
dispensing means, the beads of the tire could not be inserted into the 
well and the buttonhooking procedure would be impossible. The prior art 
has attempted to solve this problem in various ways, none of which have 
been truly satisfactory. U.S. Pat. No. 3,930,526 teaches the mounting of a 
plurality of dispensing means in the well of a drop-center rim over a 
small (90 degrees or less) sector of the circumference of the rim. While 
this structure allows the entry of the beads into the well at a point 
opposite from the sector where the dispensing means are mounted, it is 
inherently unbalanced. The entire mass of the dispensing means and the 
material contained therein in concentrated over one sector of the tire. To 
counteract this imbalance, the aforesaid patent teaches the use of an 
external balancing weight to be mounted opposite from the dispensing 
means. However, if the weight is chosen so that it exactly counterbalances 
the mass of the dispensing means and the material contained therein during 
normal operation of the tire (before release of the material from the 
dispensing means), the weight will inevitably be heavier than the 
dispensing means alone. Thus a substantial imabalance would be created 
when materials is released from the dispensing means into the inflation 
cavity and distributed throughout the tire during operation after 
deflation of the tire. 
U.S. Pat. No. 3,942,753 teaches the use of a single dispensing means which 
is placed into the well and which extends around the entire circumference 
of the rim. So that the well can accommodate the beads of the tire during 
mounting, the well must be of sufficient width or axial extent to 
accommodate the dispensing means and the beads of the tire at the same 
time. Therefore the well must have a greater axial extent than would be 
necessary if the dispensing means were not present therein. The well will 
extend closer to the bead seats than would otherwise be necessary, and 
this, in turn, will increase the chances of the tire becoming separated 
from the rim during operation after deflation. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a wheel 
rim assembly which includes dispensing means or release means and which 
allows mounting of the tire by the conventional buttonhooking technique, 
but which will not create any unbalance upon release of material into the 
inflation cavity or require any wider drop-center well than would be 
necessary in the absence of the dispensing means. 
It is a further object of the present invention to provide a method for 
mounting dispensing means and a tire on a drop-center rim which 
incorporates the conventional buttonhooking technique of tire mounting. 
It is yet another object of the present invention to provide a wheel rim 
and tire assembly including a plurality of dispensing means, which is so 
constructed and arranged that the tire may be demounted and replaced 
without disturbing the dispensing means. 
The wheel rim assembly of the present invention includes a drop-center 
wheel rim having a pair of radially extensive flanges, a pair of generally 
axially extensive bead seats located radially and axially inwardly of the 
flanges and a center portion located axially inboard of the bead seats and 
defining a well extending radially inwardly of the bead seats. A plurality 
of dispensing means are affixed to the wheel rim with at least a portion 
of each of the dispensing means lying in the well. The dispensing means 
are arranged in a balanced array. That is, the center of mass of all of 
the dispensing means taken together lies at the center of the wheel. The 
dispensing means are arranged to define at least one clear arc of the well 
between adjacent dispensing means. That clear arc has a circumferential 
extent of at least 120 degrees so that during mounting and demounting of a 
tire, the clear arc of the well can receive portions of the tire beads to 
facilitate prying the tire beads over the flanges. 
The tire and wheel rim assembly of the present invention includes a wheel 
rim assembly as aforesaid. Thus, the tire of such an assembly can be 
removed and replaced by the conventional bottonhooking technique. 
In the mounting method of the present invention, the dispensing means are 
mounted to the rim in the aforesaid balanced array before the tire is 
mounted to the rim. 
These and other objects, features, and advantages of the present invention 
will be more readily apparent with reference to the detailed description 
of the preferred embodiments set forth below, when read in conjunction 
with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The following detailed description can be best understood with reference to 
the accompanying drawings. As shown in FIG. 1, a wheel rim assembly 
according to a preferred embodiment of the present invention includes a 
drop-center wheel rim 10 having a pair of flanges 12 and 14 which extend 
radially outwardly. The wheel rim 10 also includes a pair of generally 
axially extensive bead seats 16 and 18 which are located radially inwardly 
of the flanges and also axially inwardly of the flanges (towards the 
median equatorial plane of the rim). The drop-center portion 20 of rim 10 
is located axially between the bead seats and defines a well 22 which 
extends radially inwardly of the bead seats. The aforesaid features of the 
rim are maintained, without any substantial variation, around the entire 
circumference of the rim. 
A pair of dispensing means 24 and 26 are affixed to the rim 10 so that they 
lie substantially in the well 22. 
As shown in FIG. 2, the dispensing means 24 and 26 are mounted at 
diametrically opposed locations. The two dispensing means themselves have 
substantially the same masses and configurations, and each of them 
contains substantially the same mass of material. 
The two dispensing means 24 and 26 define a first clear or unobstructed arc 
28 of well 22 on one side of the wheel and a second clear or unobstructed 
arc 30 on the other side of the wheel. Each of the release means 24 and 26 
has a circumferential extent E of about 40 degrees of arc. Thus, the two 
release means occupy in total about 80 degrees of the 360 degree 
circumferential extent of the well. Therefore, each of the clear arcs 28 
and 30 has a circumferential extent A of about 140 degrees. 
As shown in FIG. 4, dispensing means 24 preferably comprises a frangible 
shell 32 containing the requisite quantity of material 34. The shell 32 is 
affixed to the rim 10 by appropriate fastening means such as the adhesive 
layer 35. The radially outwardmost extent 33 of the dispensing means lies 
radially outwardly of the bead seats 16 and 18. The other dispensing means 
is constructed and arranged in a similar fashion. 
As shown in FIGS. 1 and 4, the tire 36 includes a pair of beads 38 and 40, 
a pair of generally radially extensive sidewalls 42 and 44 and a crown 
wall 46. 
At the initial stage of mounting shown in FIG. 1, corresponding regions 38A 
and 40A of the tire beads have been squeezed together and inserted into 
the clear arc 28 of the well 22. With the regions 38A and 40A positioned 
in the well the remaining portions of beads 38 and 40 can be pried over 
flange 12 around the remaining periphery of the wheel rim 10. 
After this has been done, the beads 38 and 40 will lie partially in the 
clear arc 28 of the well 20 and partially on the bead seat 16. Bead 38 can 
be simply adjusted until it lies in its final position on bead seat 16. To 
complete the tire mounting process, bead 40 of the tire must be moved 
axially of the rim until it rests upon the other bead seat 18. Since the 
dispensing means 24 and 26 extend radially outwardly beyond the bead 
seats, and thus extend to a greater radius than the undistorted radius of 
beads, the bead 40 which is to be moved axially must be distorted in order 
to clear the dispensing means. 
This may be accomplished as shown in FIG. 3. The portion 40a of bead 40 
lies in clear arc 28 and provides enough slack to allow portions 40c and 
40d of bead 40 to be pried radially outwardly so that they clear 
dispensing means 24 and 26 as bead 40 is moved axially past the dispensing 
means. To provide additional slack, another portion 40b of bead 40 may be 
pulled radially inwardly into the second clear arc 30, but this is not 
essential. Once bead 40 has been moved past the dispensing means and 
lodged upon bead seat 18, all that remains is to inflate the tire. 
The mounting process described above is identical with the standard 
"buttonhooking" procedure with the exception of the last step of prying 
regions 40c and 40d radially outwardly to clear the dispensing means 
during the axial movement of the bead 40. It will be apparent that the 
dispensing means 24 and 26 were mounted to the rim 10 before the tire was 
mounted to the rim. The tire may be demounted from the rim by simply 
reversing the mounting steps set forth above. The mounting and demounting 
procedures may be modified so that the beads are placed into the clear arc 
of the well and pried over the rim flanges seriatim, rather than 
simultaneously. 
The tire and rim assembly resulting from the mounting process is shown in 
FIGS. 4 and 5. The normal mode of operation is depicted in FIG. 4. With 
the tire 36 in the inflated condition, the crown or tread region 46 of the 
tire rests upon the road 48. Of course, the pressure of air in the 
inflation cavity 50 maintains the tire 36 in the shape depicted. 
As shown in FIG. 5, if the pressure in the inflation cavity is lost, the 
tire is flattened. That is, the weight of the vehicle forces wheel rim 10 
downwardly. The sidewalls 42 and 44 buckle and the crown wall 46 itself 
buckles radially inwardly. Thus, the interior surface 46a of crown wall 46 
contacts the shell 32 of the dispensing means 24 and ruptures it, allowing 
the material 34 to escape into the inflation cavity. As the assembly 
continues to roll with continued operation of the vehicle to which it is 
mounted, the other dispensing means 26 (FIG. 1) will also be ruptured and 
its material will also escape. 
The embodiment described above utilizes two identical release means mounted 
at diametrically opposed locations on the rim. Such an arrangement of 
dispensing means constitutes a balanced array before release of material 
from the release means because the release means are substantially 
identical, they contain approximately equal masses of material(s) and the 
shell of each dispensing means is of about the same mass. Therefore, after 
release of material(s) from the dispensing means and distribution of same 
around the tire by the rolling motion of the assembly, the mass of each 
empty release means will counterbalance the mass of the opposite release 
means. Thus, the balanced array will be maintained after release of the 
material. 
While the use of two diametrically opposed and identical dispensing means 
constitutes the preferred balanced array, other arrays of dispensing means 
may also be employed. One such array is depicted in FIG. 6. This array 
consists of three dispensing means. The first dispensing means 52 has a 
circumferential extent C.sub.1 of about 40 degrees. The second and third 
dispensing means 54 and 56 have respective circumferential extents C.sub.2 
and C.sub.3 each equal to about 20 degrees. The second and third release 
means are spaced apart from each other by a gap G of about 30 degrees of 
arc. Thus, the dispensing means define two clear arcs 28' and 30' each 
having a circumferential extent A' of about 125 degrees. 
To constitute a balanced array, the dispensing means must be constructed 
and arranged so that they are in "static balance", that is, so that the 
center of mass of all of the dispensing means taken together lies on the 
axis of rotation of the wheel. This condition of "static balance" will 
occur if both of the following equations are satisfied: 
______________________________________ 
n = N 
M.sub.n r.sub.n cos.theta..sub.n = O 
n = 1 
n = N 
M.sub.n r.sub.n sin.theta..sub.n = O 
n = i 
______________________________________ 
wherein: 
N is the number of dispensing means; 
M.sub.n is the mass of the nth dispensing means 
r.sub.n is the radial distance from the center of the wheel to the center 
of mass of the nth dispensing means; and 
.theta..sub.n is the angle between an arbitrarily chosen radius and the 
radius passing through the center of mass of the nth dispensing means. 
These terms are illustrated in FIG. 6. The first dispensing means 52 has 
its center of mass 53 at a radial distance r.sub.1 from the center of the 
wheel. The radius 55 of the wheel rim 10 passing through that center of 
mass lies at an angle .theta..sub.1 from arbitrarily chosen radius 57. Of 
course, the angles .theta..sub.2 and .theta..sub.3, associated 
respectively with the second dispensing means 54 and the third dispensing 
means 56, are measured from the same radius 57. 
In order to constitute a balanced array, the dispensing means must also be 
constructed and arranged so that they are in "dynamic balance"; i.e., so 
that the "centrifugal forces" generated by their masses upon rotation of 
the wheel will not impose any movement on the wheel tending to twist the 
wheel about an axis perpendicular to its axis of rotation. This condition 
of "dynamic balance" will occur if the center of mass of every dispensing 
means lies in a single plane perpendicular to the axis of rotation of the 
wheel. 
If the array is to be in balance before release of material(s) from the 
dispensing means, these conditions of static and dynamic balance must be 
satisfied with the mass of the material contained in each dispensing means 
considered as part of the mass of that dispensing. If the balance of the 
array is to be maintained after release of material(s), these conditions 
must also be satisfied taking into account only the masses of the empty 
dispensing means. 
In the embodiments described above, each dispensing means has a radially 
outwardmost extent which extends radially outwardly of the bead seats on 
the wheel rim. That configuration is useful because it assures effective 
mechanical contact between the crown wall of the tire and the dispensing 
means when the tire is deflated as shown in FIG. 5. However, as discussed 
above, one bead of the tire must be distorted during mounting in order to 
maneuver it past the protruding portion of the dispensing means. The need 
for such distortion may be eliminated if the dispensing means are 
constructed and arranged so that the radially outwardmost extent of each 
of the dispensing means lies radially inwardly of the bead seats. 
Such an embodiment is shown in FIG. 7. The dispensing means 24' has a 
radially outwardmost extent 33' which lies radially inwardly (toward the 
top in FIG. 7) of the bead seats 16 and 18 of the wheel rim 10. The tire 
36 is mounted in a manner similar to the process set forth above. However, 
as shown in broken lines, the bead 40 of the tire may be moved axially of 
the wheel rim during mounting (in the direction indicated by the arrow in 
FIG. 7) and will pass radially outwardly of the dispensing means 24' 
without stretching any portion of the bead radially outwardly. 
Upon deflation of the tire, the crown wall 46 will normally crumple and 
wrinkle to a sufficient extent so that portions of it extend radially 
inwardly of the bead seats to contact and rupture the shell 32' of the 
dispensing means. To assure that the dispensing means will be ruptured 
even if the crown wall of the tire does not wrinkle to such an extent, a 
radially inwardly projecting protuberance 60 may be affixed to the inside 
surface of the crown wall 46. 
The dispensing means may also be constructed and arranged so that they will 
respond to phenomena other than contact with the crown wall to trigger 
release of material(s) upon deflation of the tire. 
For example, one form of dispensing means includes a shell containing 
material(s) and having a hole formed therein. The hole is plugged with a 
substance having a melting or vaporization point higher than the normal 
operating temperature of the tire but lower than the temperatures which 
would be generated by operation of the tire in a deflated condition. Thus, 
release of the material(s) is triggered by the temperature rise occurring 
upon operation with the tire in a deflated condition, which causes the 
aforementioned substance to melt and/or vaporize and allow material(s) to 
escape through the hole in the shell. This type of dispensing means is 
described in greater detail in U.S. Pat. No. 3,901,301, the disclosure of 
which is hereby incorporated by reference herein. 
Because this type of dispensing means does not require mechanical contact 
between the crown wall and the dispensing means on deflation of the tire, 
it is especially useful when the dispensing means are to be configured as 
shown in FIG. 7. Of course, there is no need for protuberance 60 depicted 
in FIG. 7 if this thermally responsive type of dispensing means is used. 
Other types of dispensing means include various valve mechanisms. Such 
valve mechanisms may be actuated either by mechanical contact with the 
crown wall of the tire, a loss of pressure within the inflation cavity of 
the tire, or the heat generated within the tire upon operation in the 
deflated condition. Any of these valve arrangements may be used in an 
assembly of the present invention. 
Each dispensing means may include both a dispensing portion (such as the 
rupturable shells or valve mechanisms described above) mounted in the well 
of the wheel rim and a separate reservoir mounted to the wheel rim at a 
location remote from the tire. Each dispensing portion is in communication 
with its respective reservoir by means of a conduit passed through a hole 
in the wheel rim. 
Any of the numerous types of material(s) known to those skilled in the art 
may be contained within the dispensing means. For example, the various 
lubricants and reactive mixtures set forth in U.S. Pat. No. 3,850,217, the 
disclosure of which is hereby incorporated by reference herein, may be 
utilized. If a multi-component reactive mixture is utilized, each 
component may be placed in a different dispensing means, or one component 
may be placed in the inflation cavity and the other component or 
components may be contained in the dispensing means, or separating 
techniques such as micro-encapsulation could be used to permit mixtures of 
material(s) in each dispensing means. 
To avoid dislodgement of the tire from the rim during operation with the 
tire in a deflated condition, various devices can be utilized to prevent 
the beads from dropping into the well of the rim during such operation. 
For example, studs or locking elements can be provided to clamp each bead 
against the adjacent flange of the wheel rim. A great number of such 
locking devices are known to those skilled in the art. If such devices are 
employed, they should be arranged so that they do not interfere with the 
mounting of the tire on the rim. One such device is described in Canadian 
Pat. No. 971,472, issued July 22, 1975. 
It should be clearly understood that a great number of variations and 
combinations of the features set forth above may be utilized without 
departing from the spirit of the present invention as set forth in the 
appended claims.