Self-balancing wheel for motorized vehicles

The invention relates to a motor vehicle wheel capable of improved dynamic self-balancing against imbalancing forces in the X, Y and Z planes. The wheel comprises a hub portion and an annular rim portion integral with the hub and extending circumferentially around the hub portion. The rim has inner and outer flanges adapted for securing a tire to the wheel. The rim portion is provided with a circumferential integral annular channel containing a quantity of balancing fluid having a relatively high boiling point and a relative low freezing point and whose remaining physical properties are not negatively affected by adverse environmental conditions. As the wheel rotates, the fluid spinning within the channel will substantially instantaneously counteract imbalances within the wheel and tire combination caused by irregularities due to, e.g., valve stems, dents and attached road debris by migrating to a location within the channel directly opposite the imbalancing force.

TECHNICAL FIELD 
The invention is directed to means for dynamically balancing a rotatable 
object while in motion and, more particularly, to a self-balancing wheel 
for use on motorized vehicles. 
BACKGROUND OF THE INVENTION 
When the wheel of a motorized vehicle, such as an automobile, rotates at 
high speed, it is important that the wheel be properly balanced. At low 
speeds imbalance causes only minor difficulties, but with modern high 
speed vehicles and roads an unbalanced wheel presents major problems. In 
an unbalanced condition the wheel's center of mass does not coincide with 
its center of rotation, causing the wheel to vibrate and/or bounce on the 
pavement and leading to a number of undesirable effects. These effects 
include a shimmy in the steering mechanism of the vehicle, uneven wear on 
the tires and increased wear on breaking systems, front-end suspension 
systems and the like. 
The common remedy in the case of passenger cars and other motorized 
vehicles for the conditions described above is to have the vehicle's 
wheels balanced. Various means have been utilized in the prior art for 
this purpose. One common wheel balancing technique is static balancing by 
the use of lead weights. In common practice such weights are typically 
clamped to the rim portion of the wheel. In an alternate arrangement, 
however, as described in U.S. Pat. No. 3,786,850 to Turocci, Jr., the 
weights may instead be attached to the outer surface of the tire. 
While such weights may generally improve the wheel balance, they are 
incapable of producing optimal results since their position on the wheel 
is fixed and they thus tend to compensate for only a single imbalancing 
condition. Therefore, in the event that the condition changes due to tire 
wear or some other cause, the balancing effect provided by the weights is 
no longer effective. Further, installation of such weights typically 
requires the service of experienced mechanics and specialized equipment. 
Moreover, each time a new or repaired tire is installed on a wheel, the 
balancing operation must be repeated. Weights are frequently lost or 
misplaced when repairing or changing tires. Therefore, a large percentage 
of vehicles presently on the road are typically operated with unbalanced 
wheels, and are therefore prone to many of the problems described above. 
There has thus been a continuing interest, among those working this field, 
in the development of balancing means adapted to be permanently mounted 
upon a vehicle wheel. It has been further deemed desirable that such means 
be capable of continuous operation as the wheel rotates to provide a 
dynamic counterbalancing effect to offset any static imbalance existing or 
created in the Wheel and/or tire assembly. In this regard, various dynamic 
balancing mechanisms or devices have been developed in the prior art which 
are adapted for installation upon the wheel of a motor vehicle. Most such 
devices, as described below, incorporate in some manner a quantity of 
weighted elements and/or a damping fluid which is distributed about the 
rotational axis of the wheel, as the wheel rotates, to a position 
diametrically opposite to the mass tending to cause imbalance to the wheel 
and/or the tire to provide a partial counterbalancing effect. 
As described, e.g., in U.S. Pat. Nos. 3,164,413 and 3,316,021 to Salathiel; 
3,346,303 to Wesley; 3,376,075 to Mitchell and 5,253,928 to Patti, in one 
version of such prior art dynamic balancing devices, the weights and/or 
fluid are contained within a hollow annular hoop member which is secured 
in some manner, e.g., with the use of fasteners, to the outer surface of 
the hub portion of the wheel. 
U.S. Pat. Nos. 3,164,413 and 3,316,021 to Salathiel describe a hollow 
annular hoop containing a plurality of spherical weights and a damping 
fluid. The annular hoop is made of a plastic material. In use, the hoop is 
attached to a rotating wheel and the weights are free to move within the 
hoop. The damping fluid reduces noise as well as restricts the free 
movement of the weights. The weights are urged toward the point in the 
hoop which offsets the imbalance of the wheel. 
The apparatus described in the Salathiel patents, however, has the 
disadvantage of using a deformable material, i.e., a plastic, for the 
annular hoop. Under conditions of rotation at high speed the hoop can 
bulge where it is free to move and this loss of concentricity causes an 
imbalance to the device. Loss of concentricity of the hoop can also 
prevent free movement of the weights. 
U.S. Pat. No. 3,346,303 to Wesley describes a hollow annular hoop 
containing a plurality of spherical weights and a measured amount of 
damping fluid. The hoop has an apex at its outer perimeter and is adapted 
with the outer apex to provide reduced areas of contact between the 
spherical weights and the hoop when the hoop is rotated. The hoop is 
constructed of a metal formed or welded into the proper shape or 
configuration and is attached to the wheel of the vehicle by use of a 
mounting fixture which has several precut lug nut holes adapted to fit the 
wheel. 
U.S. Pat. No. 3,376,075 to Mitchell describes a dynamic wheel balancing 
device which includes a hollow annular hoop with a plurality of spherical 
weights and a damping fluid. The hoop is attached to a mounting fixture 
which is adapted to fit a variety of wheel and lug nut configurations. The 
annular hoop is constructed by attaching a U-shaped channel onto a plate 
in a fluid tight manner. 
U.S. Pat. No. 5,253,928 to Patti describes a method for attaching a dynamic 
wheel balancer to a vehicle wheel. The balancer is a hollow annular tube 
containing metal balls and a damping fluid, e.g., an oil. The wheel 
balancer is concentrically mounted against the wheel, preferably against 
the outside of the tire rim. The balancer may be installed by either 
placing it within a recess formed in a wheel cover and attaching the wheel 
cover to the wheel, or alternately, by placing the balancer against the 
wheel and holding it in place with, e.g., adhesive tape while the wheel 
cover is attached. 
One drawback to the use of balancing means including spherical weights as 
described above for the dynamic stabilization of a tire and/or wheel 
assembly is that the surfaces of the balancing spheres tend to suffer from 
some limited degree of corrosion over time. The resultant corroded 
surfaces tend to become wetted and sticky by exposure to the damping fluid 
which is employed. The balancing spheres thus tend to bunch up and stick 
together. They stick together with increasing frequency and tenacity as 
the balancing weights are reduced in size, thus exposing a larger wetted 
surface to the other balancing weights. Under such conditions, therefore, 
groups of such weights tend to become wedged when attempting to pass one 
another or in passing a weight stuck to the inner surface of the annular 
tube or hoop. 
Another significant disadvantage to the use of the dynamic balancing means 
described above is that such means require the vehicle owner to "add on" a 
heavy awkward ring structure to the vehicle wheel. The use of such a 
device not only requires significant time and effort for its installation, 
but also adds appreciably to the weight of a vehicle wheel so equipped. 
Thus, in a further effort to at least partly overcome the disadvantages 
discussed above, there has been developed dynamic stabilizing means 
installed upon an inner surface of a motor vehicle wheel between the 
flanges comprising the wheel rim. One major drawback of such means, 
however, is that they typically protrude upwardly into the air cavity of 
the tire, thus filling in the drop center of the rim, thereby interfering 
with the ability to mount and dismount the tire from or onto the rim. In 
an effort to overcome this problem, internal dynamic balancing devices 
have been developed which are adapted to be recessed below the drop center 
of the wheel. An example of such an arrangement is illustrated in U.S. 
Pat. No. 2,737,420 to Wilborn. 
The Wilborn patent describes a means for dynamic balancing of motor vehicle 
wheels embodying a wheel comprising a rim portion having an annular recess 
and a band positioned upon the rim providing a closure for the recess so 
as to form an enclosed channel running around a central portion of the 
wheel. This channel may be provided with a plurality of globular balancing 
elements and a quantity of damping fluid which circulates around the 
circumference of the wheel during rotation to produce a dynamic balancing 
effect while the wheel is in motion. 
The arrangement described in Wilborn, however, suffers from a significant 
drawback in that the dynamic balancing forces thus provided are brought to 
bear only within an inner central annular portion of the wheel mass. Thus 
there is only limited balancing of vector forces along the X (side to 
side) and Y (up and down) planes and no balancing at all of the vector 
forces along the Z (yaw-type movement) plane. Moreover, in addition no 
balancing effect is obtained with the use of means such as those described 
in Wilborn at the outer fringes of the wheel where it is needed most, 
i.e., at the flange portions of the wheel rim, which are the most likely 
areas to require balancing due to the unbalancing effects of tire 
irregularities, the presence of valve stems, dents due to impact with 
curbs, potholes, etc. and the attachment of road debris. 
SUMMARY OF THE INVENTION 
It is therefore a principal object of the present invention to provide a 
wheel for use on motorized vehicles which is capable of an improved degree 
of dynamic self-balancing wherein the balancing effect is capable of 
correcting imbalancing vector forces in three dimensions, i.e., along the 
X, Y and Z planes. 
A further object of the invention is to provide a wheel for use on 
motorized vehicles comprising balancing means formed integrally therewith 
wherein the balance of the wheel is continually adjusted as the wheel is 
in motion and wherein the balancing means remains in operation 
continuously throughout the life of the wheel without the need for any 
maintenance. 
Another object of the invention is to provide a continuously balanced wheel 
for motorized vehicles which is of a simple and economic construction. 
A still further object of the present invention is to provide a 
self-balancing wheel for motorized vehicles wherein dynamic balancing 
means formed integrally thereupon does not protrude into the drop center 
of the wheel and thus does not interfere with the mounting or dismounting 
of tires onto or off of the wheel. 
The present invention is therefore directed to a continuously dynamically 
self-balancing motor vehicle wheel which is adapted to provide balancing 
forces to instantly and continuously counterbalance imbalancing vector 
forces in three dimensions, i.e., along the X, Y and Z planes, thus 
substantially preventing undesirable up and down (i.e., Y plane), side to 
side (X plane) and yaw-type movement (i.e., in the Z plane) of the tire 
and wheel assembly which may otherwise occur due to the presence of such 
imbalancing forces. 
In a first embodiment of the invention, the wheel comprises a centrally 
located hub portion and an annular outer rim portion integral with the hub 
portion and extending circumferentially around the hub portion. The rim 
portion comprises a pair of flanges, i.e., an inner and outer flange, 
separated by an annular trough. The hub portion defines a centrally 
located aperture configured and adapted to allow passage of the axle hub 
to permit rotation of the vehicle wheel. The hub portion is additionally 
provided with a plurality of lug bolt holes adapted to permit passage of 
lug bolts attached to the vehicle brake drum which are adapted for 
securing the wheel to the vehicle. 
A hollow annular chamber is formed integrally within the rim portion of the 
wheel, extending without interruption around the entire circumference of 
the wheel. The channel traverses substantially the entire width of the 
wheel, extending into both the inner and outer flanges of the wheel rim. 
The member forming the upper surface of the chamber forms the annular 
trough which, as discussed above, separates the inner and outer rim 
flanges. 
A quantity of a balancing fluid is deposited within the chamber through a 
drain plug in the wheel rim. The chamber is not entirely filled with the 
fluid, but rather a sufficient amount is added to fill the chamber 
approximately one-quarter to one-half full when the wheel is at rest. This 
ensures that there will be a sufficient amount of the fluid to counteract 
any imbalancing forces to which the wheel and tire assembly may be 
subjected. The preferred balancing fluid for use with the invention is a 
liquid with a relatively high boiling point and low freezing point, whose 
viscosity is not appreciably affected by changes in temperature or other 
environmental conditions. 
As the wheel rotates, it becomes subject to imbalancing forces caused by, 
for example, tire irregularities, dents and attached road debris. The 
balancing fluid circulating throughout the chamber portion of the rotating 
wheel therefore instantly migrates to those areas of the chamber opposite 
the imbalancing force to provide a continuous counterbalancing force in 
opposition thereto, thus substantially preventing undesirable up and down, 
side to side and yaw-type movement of the wheel in the X, Y and Z planes 
when the vehicle is in motion. 
In a further embodiment of the invention, the chamber may be extended from 
the wheel rim into the hub portion of the wheel. This arrangement enhances 
the instant, continuous balancing effect described above since allowing 
the balancing fluid to circulate within at least a portion of the wheel 
hub, as well as through the wheel rim, permits it to counterbalance an 
even further increased (i.e., in contrast to the prior art) number and 
degree of imbalancing forces. 
In the preferred embodiment, it is desirable to extend the chamber only 
upon the outer side of the wheel. This is because, as one skilled in the 
art would recognize, although it would also be beneficial in theory to 
extend the chamber along the inner face of the wheel hub to permit the 
balancing fluid to circulate therein as well, practically speaking the 
feasibility of such an arrangement must take into account the additional 
clearance space required on the inner surface of the wheel for braking and 
stabilizing mechanisms associated with the motor vehicle. Thus a 
significant modification of the wheel construction would be required in 
order to construct a wheel having such a configuration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the accompanying drawings and the following specification, the same 
reference characters are used to designate the same parts and elements 
throughout. 
Turning initially to FIG. 1 there is illustrated the general outward 
appearance of motor vehicle wheel 10 of the invention. Wheel 10 comprises 
a central hub portion 12 and an annular rim portion 14 integral with the 
hub portion and extending circumferentially about the hub portion 12. Hub 
portion 12 defines a central opening 26 configured and adapted for passage 
of the hub of an axle (not shown) to permit rotation of wheel 10. In 
addition, hub portion 12 further defines a plurality (i.e., usually four 
or five) of lug bolt holes 28 for use in mounting wheel 10 to the axle and 
brake drum assembly (not shown) of a motor vehicle. 
As shown more clearly in FIGS. 2-4, rim portion 14 of wheel 10 comprises 
inner flange 16 and outer flange 18 separated by a trough-shaped member 20 
having a flat-bottomed annular depression 22. Member 20 also forms the 
upper surface of the annular balancing means of the invention as described 
below. As used herein, the term "inner" and/or "inwardly" is used to 
designate that portion of wheel 10 which faces toward the motor vehicle, 
i.e., most nearly adjacent the brake drum. The terms "outer" and/or 
"outwardly" on the other hand, are used to refer to that surface of wheel 
10 which faces away from the vehicle. 
FIG. 2 is a cross-sectional view through wheel 10 illustrating a first 
embodiment of the invention. As can be seen from the figure, wheel 10 
includes an integrally formed hollow annular chamber 30 extending 
uninterruptedly around the entire inner circumference of the wheel rim, 
from and including the inner flange 16 to the outer flange 18 of rim 
portion 14, bordered upon its upper surface by member 20 and upon its 
lower surface by member 24 formed integral with hub portion 12. Chamber 30 
comprises first and second compartments extending, respectively, into 
inner 16 and outer 18 flanges, having, in the preferred embodiment, 
substantially equal volumes. Chamber 30 further comprises a third 
compartment between the first and second compartments and formed integral 
therewith for connecting the first and second compartments to each other. 
The third compartment has a relatively smaller volume than the first and 
second compartments in that member 20 which defines the upper surface of a 
chamber 30 has a depression 22 along its central portion for the purpose 
of providing a drop center within the rim 14 to facilitate mounting and 
demounting of tires from the wheel. 
The configuration of chamber 30 is novel in that, as shown in FIG. 2, it 
extends across substantially the entire width of wheel 10 into the inner 
and outer flanges 16, 18 of rim portion 14. This permits, as explained 
below, a more complete and truer balance of wheel 10 than has previously 
been achieved with prior art balancing devices. 
Within chamber 30 is hermetically sealed a quantity of a balancing fluid 32 
which is added to the chamber through drain plug 34. Chamber 30 is not 
entirely filled with fluid 32, since to do so would slow down passage of 
the fluid through the chamber and thus significantly reduce the balancing 
capabilities of the fluid. In practice, it is preferred to add a 
sufficient amount of balancing fluid to fill chamber 30 approximately 
one-quarter to one-half full, e.g., from about 8 to about 32 fluid ounces, 
depending upon the relative size of the wheel. This ensures that there is 
enough fluid to obtain the desired balancing effect. The actual number of 
fluid ounces of liquid used would, of course, depend upon the size of the 
wheel. Thus it would be a relatively simple matter for one skilled in the 
art to determine the amount of liquid to be added to each sized wheel 
which is available. Fluid 32 runs down to the lower portion of wheel 10 
when the vehicle is stationary. 
In operation, however, the dynamic balancing action is produced when the 
fluid 32 moves as the wheel rotates, under the action of imbalancing 
vector forces in the X, Y and/or Z planes, toward the portion of the wheel 
opposite the force which is causing the imbalance. This action produces a 
substantially instant and continuous correction for such imbalancing 
forces by obeying Newton's law of motion, i.e., for every action there is 
an equal and opposite reaction. The shape of chamber 30 as configured in 
the present invention permits balancing fluid 32 to reach the extreme 
inner and outer edges, respectively, of wheel 10, i.e., by extending into 
flanges 16 and 18, thus providing three-dimensional counterbalancing 
forces against the X , Y and/or Z plane vector forces to prevent 
undesirable side to side, up and down and yaw-type movement of the wheel. 
The fluid 32 located within chamber 30 is preferably a liquid having a 
relatively high boiling point, a relatively low freezing point and whose 
viscosity is not appreciably changed due to changes in temperature or to 
other environmental conditions. The liquid may be aqueous or non-aqueous. 
The liquid should additionally be non-flammable to avoid any hazard due to 
leakage in case of, e.g., an accident involving the motor vehicle where 
the liquid may escape from the wheel. Additionally, it should be noted 
that the balancing action of the present invention occurs solely due to 
the action of the balancing fluid. That is, wheel 10 of the invention 
requires no weighted elements in contrast to many prior art balancing 
means. Thus wheel 10 is significantly quieter than prior art motor vehicle 
wheels when in motion. 
Fluid 32 may be aqueous or non-aqueous. Some non-limiting examples of 
preferred fluids 32 for use with the invention are glycerin, ethylene 
glycol and hydraulic fluids such as those which are used in the 
transmission or brake system of an automobile. In addition to the 
materials noted above, silicon-based fluids, such as the material 
manufactured by the General Electric Company under the trade name SF 96 
and sold for use as a lubricant and oil defoamer, are also useful with the 
invention. The subject silicon-based materials have the following physical 
characteristics: 
______________________________________ 
Pour Point -120.degree. F. 
Thermal Expansion (cc/cc/c) (32.degree.-302.degree. F.) 
.00105 
Viscosity (77.degree. F.) 
5 centistokes 
______________________________________ 
As would be readily understandable to one of ordinary skill in the art, 
however, a variety of balancing liquids are capable of meeting the 
requirements of the present invention and thus the materials listed above 
are provided only as examples of useful fluids, i.e., they should not be 
construed as limiting the invention. In general, fluids 32 for use in the 
present invention should have the following physical characteristics which 
are readily determinable by one of ordinary skill in the art without any 
undue experimentation: 
______________________________________ 
Minimum Freezing Point 
-120.degree. F. 
Minimum Boiling Point 
330.degree. F. 
Maximum Thermal Expansion 
5.7% (32.degree. F.-180.degree. F.) 
(aqueous fluids) 
Maximum Thermal Expansion 
0.00105 (32.degree.-302.degree. F.) 
(non-aqueous fluids) 
______________________________________ 
Further to the above, as can be seen, e.g., in FIGS. 2-4, chamber 30 is 
recessed below the level of inner and outer rim flanges 16, 18 
respectively. In particular, the depression 22 in member 22 maintains 
intact the drop center of wheel 10. Therefore, the balancing means of the 
invention neither inhibits nor interferes with the removal or mounting of 
the tire upon wheel 10 at rim portion 14 in the normal fashion. 
Turning now to FIG. 3 there is shown an alternate embodiment of the 
dynamically self-balancing wheel 10 of the invention. In the subject 
embodiment chamber 30 is extended into hub portion 12 along the side 
thereof adjacent the outer face of the wheel. Thus the instant, continuous 
balancing effect obtained with the invention is further improved since 
fluid 32 is therefore able to exert its counterbalancing forces beyond the 
annular surface of the wheel circumference and into the lateral surface of 
the wheel hub. This arrangement therefor provides an enhanced degree of 
three-dimensional counterbalancing along the X, Y and Z planes. 
FIG. 4 illustrates a still further embodiment of the invention which is 
substantially similar to that shown in FIG. 3, except that in the 
embodiment depicted in FIG. 4, chamber 26 extends all the way out to the 
very outer peripheral edges of flanges 16 and 18. This further enhances 
the instant, continuous dynamic balancing effect obtained by permitting 
the balancing fluid 28 to migrate to the extreme outer fringe of the tire 
bead area. 
As described above, therefore, the dynamically self-balancing motor vehicle 
wheel of the present invention offers several significant benefits over 
prior art balancing means. These benefits include: 
the balancing means of the present invention is formed integrally as part 
of the wheel, thus eliminating the need to "add on" a cumbersome, weighty 
balancing ring as used in some prior art balancing devices. It also 
eliminates the possibility of mechanical failure or damage to the 
balancing mechanism due to impact when the vehicle wheel is in motion; 
the balancing means of the present invention is recessed below the level of 
the rim flanges and thus the drop center of the wheel is maintained to 
facilitate the mounting and demounting of tires upon the wheel; 
the wheel of the invention operates more quietly than wheels equipped with 
many prior art balancing devices since there is no mechanical device or 
added metallic balancing spheres which, upon rotation, may create noise 
within the wheel; 
under normal operating conditions, the balancing means of the invention 
will never require servicing during the life of the wheel since the fluid 
is hermetically sealed within the chamber; and 
the shape of the annular chamber allows the balancing fluid to reach the 
outer portions of the tire bead area, thus promoting a condition of truer 
balance in the wheel and tire combination since it is able to 
substantially instantaneously counterbalance forces in each and/or any of 
the X, Y and Z planes. The fluid balancing medium is also more evenly 
distributed inside the wheel, both at rest and in motion, than in prior 
art motor vehicle wheels. 
While it is apparent that the invention herein disclosed is well calculated 
to fulfill the objects above stated, it will be appreciated that numerous 
modifications and embodiments may be devised by those skilled in the art, 
and it is intended that the appended claims cover all such modifications 
and embodiments as fall within the true spirit and scope of the present 
invention.