AU682376B2

AU682376B2 - Tire balancing

Info

Publication number: AU682376B2
Application number: AU70661/94A
Authority: AU
Inventors: Russell J Freeman; Michael Heffernan
Original assignee: M&R Tire Products Inc
Current assignee: M&R Tire Products Inc
Priority date: 1993-06-17
Filing date: 1994-06-17
Publication date: 1997-10-02
Anticipated expiration: 2014-06-17
Also published as: EP0705174A1; CA2098643C; JPH09501368A; AU7066194A; WO1995000347A1; CA2098643A1

Description

'A \(1I kAtfl 00I 7. 1 0 +40 0-aoj' 2.ui at Title Of The Invention TIRE BALANCING Technical Field This invention" relates to an Improvement In a method of balancing tires using a free flowing material within a tire casing and in the composition of said material, Background Art Most tire and rim assemblies require balancing to prevent vibration within the vehicle while it Is in motion. One currently popular, method of balancing tire and rim assemblies Involves rotation of the assembly on a computerized balancing machine to determine the location and size of weights necessary to obtain balanced rotation. Lead weights of the determined size are then clamped to the assembly at the indicated points to complete the balancing procedure. There are other similar 'fixed weight" systems known for tire balancing.

Some disadvantages of this type of system are that tire balancing equipment is expensive, tire balancing requires a skilled operator and is time consuming, and tires must be rebalanced at regular intervals due to effects of varying tread wear.

Continuous self balancing systems overcome many of the disadvantages of the above fixed weight systems. Continuous self balancing systems use the principle that free flowing materials contained in a vessel In rotation will seek a distribution in balance about the centre of rotation and will tend to offset, by mass damping, any imbalance inherent in the vessel. The effectiveness of a dynamic balancing system is dependent in part on the ease with which balancing material can move within the vessel to positions which offset points of imbalance, In one application of this principle an annular ring is placed circumferentially about a rim and partially filled with heavy materials that will flow under the influence of centrifugal force.

One such balancer uses mobile weights such as ball bearings which are free to roll to any point on the ring. The effectiveness of this method is limited by the roundness of the ball bearings, the concentricity of the ring to the geometric axis and the inherent rolling resistance of the balls in the ring.

Liquids have been attempted in self balancing systems to improve the mobility of the balancing material. U.S. 2,687,918 to Bell discloses an annular tube attached to a tire rim partially filled with mercury for continuous balancing of the tire and rim assembly. Several disadvantages exist for this method, the principal ones being high cost and toxicity of mercury, the difficulty of ensuring concentricity of the annular tube and the need for special rims.

1 AMENDED

SHEET

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The disadvantages of a liquid balance are also found in U.S. 4,137,206, wherein the chemical used are toxic to humans and the environment. Moreover, in this patent the liquid composition is primarily concerned with treating metallic belt reinforced tires to Inhibit corrosion of the wire belting; tire balancing is ancillary.

The use of free flowing powdered materials in balancing compensators was taught in U.S. patent 4,109,549, in which an annular tube was filled with other dense materials such as powdered tungsten.

A different means for applying the self balancing principle was disclosed in U.S.

5,073,217 to Fogal. A free flowing balancing powder was placed directly within a pneumatic tire, instead of within a concentric annular tube. Putverent polymeric/copolymeric synthetic plastic material in the range of 8-12 screen size and 40-200 screen size were disclosed. The patent taught that the powder within the tire would distribute within the tire under centrifugal forces to dampen vibration. Placing the balancing media within the tire has two primary advantages. The balancing force is positioned close to the point of Imbalance and extraneous annular rings are not required. The disadvantage of Fogal is that powdered products produced from a grinder or pulverizer tend to have particles with an irregular shape which increases resistance or friction to fluidity.

Another patent, namely U.S. 3,230,93Z also discloses use of a mineral crushed powder as the as the principal ballast mixture. Again the irregular particles increase resistance or friction to fluidity. This is suitable, however, for the function of the mixture of U.S. 3,230,999, which Is to completely fill a tire to add ballast or weight, and is ideally suited for slow moving off-road vehicles.

It is unlikely that heavy liquids, such as mercury, could be substituted advantageously in these applications, however, both because of above mentioned safety reasons and because such liquids may be incompatible with or corrosive to the composition of a tire.

A further compound is disclosed in GB-A-2 074 955 wherein a friction reducing layer is provided between the inside tire surface and a supporting surface of a supporting device for bearing a load when the tire is punctured. The friction reducing layer comprises a gel based on polyglycol and silicon oxide, which is applied to the tire surface before assembly of the tire.

Into this gel is placed the particles. This invention has not considered the balancing effect of its mixture, however. In particular, the mixture of liquid and solids would contribute to an imbalance at highway speeds due to the formation of a slow moving gel within the tire cavity.

2A It is an object of the present invention to provide a method of tire balancing using an improved solid particulate material within a tire casing to obtain better fluidity for more efficient balancing of a tire and rim assembly.

Disclosure of Invention According to one aspect of the invention there is provided a system for balancing motor vehicle wheel assemblies, including, in combination, a. A tire and rim assembly; and b. A balancing mixture, said mixture comprising a first weight portion of first beads having a first density and a first bead size and a second weight portion of second beads having a second density and a second bead size wherein said first weight portion is smaller as a weight percentage than said second weight portion, said first density is greater than said second density and said first bead size is smaller than said second bead size.

According to another aspect of the invention there is provided a method for balancing a tire rim assembly including the steps of, ~providing a tire rim assembly having a hollow tire casing surrounding a space about the rim, said space to be filled and pressurized with air; the invention including pouring a mixture into the interior of the tire casing, said mixture including a 20 first weight portion of solid beads having a first density and a first size and a second weight portion of solid beads having a second density and a second size "°"wherein said first portion is smaller than said second portion, said first density is grater than said second density and said first size is smaller than said second size; and rotating the tire rim assembly to distribute the material within the tire 25 casing to offset forces of imbalance.

o CA WINWORD\YUEVARIOUOUACDELp7os6OlOC r*vi I 'U Il. t tL ILu uIotAr Ir^ lot It Is an object of the present Invention to provide a method of tire balani=n n ,4 improved solid particulate material within a tire casing oj ihta't-befiudity for more efficient balancing of a tire and rimss The present invention uses the known principle of balancing through mass damping and the known method of using a solid materials within a pneumatic tire to obtain a dynamic balance while the wheel Is In rotation. The improvement of this invention ties primarily in the composition of the mixture of the balancing material. The mixture comprises small, dense beads and larger, less dense beads. Beads of a substantially rounded shaped reduce friction and improve the mobility of the material during balancing.

The small, dense beads may be formed of atomized metallic particles which form during atomization as tiny balls. Corrosion resistant metal such as bronze, brass, zinc, tin, copper, stainless steel, nickel or silver or alloys of same' may be used. Selection may be made after consideration of factors such as cost, availability and suitability for forming into small rounded shapes. In preferred embodiments the metallic component is selected from bronze, brass or zinc and atomized to form tiny balls, hereafter called "micro-spheres". The micro-spheres have round surfaces which permit them to roll over each other with less friction than sharp edged particles. The metallic micro-spheres have the greatest density (about 5-9 gr/cm3) of the materials in the mixture so that they are urged to the outside of the other materials during rotation. The small size of the micro-spheres enables them to filter through the other materials during rotation. The interior circumference of a tire is usually riddled with small pockets and ridges produced during the tire moulding process. These surface defects cause erratic movement of the balancing media and reduce its effectiveness. During rotation the microspheres are forced against the tire casing to fill in imperfections or voids on the tire wall to form a smooth lining which allows the remaining balancing media to move about the tire casing with less impediment. The excess of the micro-spheres, after voids and ridges are levelled, act as part of the balancing material and move to offset points of imbalance.

The larger, less dense beads are also rounded and may be formed from glass, ceramics, alumina, corderite, porcelain or titanates. These beads function as the primary balancing material and form the largest portion by weight of the mixture, Glass spheres or beads of density 2- 3 gr/cm3 are preferred. The glass beads are larger but less dense than the metallic micro-spheres. Thus the glass beads tend to ride over the metallic micro-spheres to 3 AMENCO SNEET move easily to points of imbalance to darmpn vibrational energy. The glass beads are more durable than thermoplastic particles of Fogal and less prone to degradation.

The mixture may also Include a partitioning agent, such as vermiculite, mica or other monoclinic non-reactive crystalline minerals, to separate and lubricate the mixture to enable all components of the mixture to maintain free-flowng characteristics. Vermiculite is preferred.

A suitable desiccant, such as silica gel, A1203, CaCI2 or CaS04 may be added to the mixture to prevent agglomeration in the presence of moisture. Silica Gel Is preferred as a desiccant to maintain a dry atmosphere In the tire casing, The small particles used in this type of balancing system tend to be hydroscopic and may agglomerate in the presence of moisture.

Agglomerated panicles will cause a dramatic reduction in balancing efficiency. The silica gel tends to ameliorate this condition, A preferred mixture of this invention is as follows.

MATERIAL SIZE CONCENTRATION Non-ferrous atomized metal 80 325 mesh 10 bronze or brass) Glass beads 20 40 mesh 40 (Lead free soda lime type) Vermiculite 20 325 mesh 10 Silica Gel 20 40 mesh 2 4% It has been found that this invention will work effectively with any conventional multiwheel vehicle tire and rim assembly. It will be appreciated, however, that the amount of material to balance a particular assembly will vary in quantity and proportion, according to the type of assembly and the size of the tire and rim assembly. Correct amounts and proportions may be determined empirically by persons skilled having the benefit of this disclosure and the current state of the art. To illustrate in general terms, a steering tire of a truck (11 x 24.5) may require about 400 grams while a truck driving tire may require 500 grams of the mixture. Automobile I V. W Ji ,U n 0 01 077 l3l1:.t +4 1-1I 1110 ;f H tires may require only 160 grams of the mixture but are much more sensitive to vibration than truck tires and therefore require more vehicle specific and careful measuring, Brief Description of Drawings In the figures* which Illustrate a preferred embodiment of this invention: Figure 1 is an illustration of a lire and rim assembly cut away to show the interior of the tire casing having the balancing material of this invention; Figure 2 is an illustration of a cross section of a tire and rim assembly showing the balancing material of this invention; and Figure 3 Is a side sectional view of a tire showing the distribution of the mixture of this invention.

Best Mode (or Modes) for Carrying Out the Invention In the figures illustrating this invention like numerals indicate like elements, In Figure 1, a tire is shown mounted'on a rim which, in turn, is mounted on an axle of a vehicle The Interior of the tire casing is ordinarily filled with air. The balancing material of this invention lies about the periphery of the tire casing while the wheel is in rotation by reason of the centrifugal force exerted on the material As illustrated in Figure 2, the interior of the tire casing has many voids and surface irregularities (which are accentuated in the illustration).

The atomized metal micro-spheres are shown to lie in and about the surface irregularities of the tire casing The micro-spheres fill the voids and surface irregularities and form a smooth, slippery surface for movement of the remainder of the balancing material, The excess of the micro-spheres acts as balancing material. Glass beads roll over the micro-spheres and act as the primary balancing material. Vermiculite (not shown) and silica gel (not shown) are interspersed in the material to act as a lubricant and a desiccant, respectively.

The preferred proportions of the balancing mixture for use in truck tires is as follows: atomized metal 17% glass beads vermiculite silica gel 3% AMENDED

SHEET

E\o\ f W\C 5 077 0.41(J;- +4Iu 1u ,1itJ .4t7j;M n For automobile tires, the preferred mixture is: micro-spheres 24% glass-beads vermiculite 9% silica gel 2% In operation, the balancing mixture may be poured into a new tire casing as It is assembled onto a rim. In tire rim assemblies previously constructed, the sealing bead about the rim may be broken and the mixture poured into the tire casing. Altematively the mixture may be poured into the valve stem or mixed with the air which pressurizes the tire. Once a tire on a vehicle begins to rotate, the balancing material distributes itself within the tire casing As the speed of rotation increases, the metallic micro-spheres tend to filter to the outside adjacent the tire casing and to fill the voids and surface irregularities thereby forming a smooth inner surface. The lighter and larger glass spheres then roll over the micro-spheres to adjust to a position opposite a point of imbalance As illustrated in Figure 3, the material distributes within the tire casing so that a thicker portion of the material lies opposite the point of imbalance while some of the balancing material is distributed about the entire inner surface of the tire casing The distribution of the balancing material acts as mass damping to overcome the eccentric force which would otherwise be introduced by the point of imbalance so that the tire turns smoothly, 6 AMENDED SHEET

Claims

1. A system for balancing motor vehicle wheel assemblies, including, in combination, a. A tire and rim assembly; and b. A balancing mixture, said mixture comprising a first weight portion of first beads having a first density and a first bead size and a second weight portion of second beads having a second density and a second bead size wherein said first weight portion is smaller as a weight percentage than said second weight portion, said first density is greater than said second density and said first bead size is smaller than said second bead size.

2. A mixture according to claim 1 having a third portion of a partitioning and lubricating particulate material.

3. A mixture according to claim 1 having a third portion of vermiculite.

4. A mixture according to any one of the preceding claims having a further portion of a desiccant.

5. A mixture according to claims 2, or 3, having a fourth portion of a desiccant.

6. A mixture according to any one of claims 1 to 3 having a further S- 20 portion of silica gel.

7. A mixture according to any one of claims 1 to 3 having a fourth se portion of silica gel.

8. A mixture according to any one of claims 1 to 7, including; a first Sportion in a range of 15% to 30% by weight of the mixture of first beads having a 25 specific gravity in the range 5-9 and a mesh size in the range of 80-325; and a o second portion in a range of 70% to 85% by weight of the mixture of second beads having a specific gravity in the range of 2-3 and a mesh size in the range of 20-40.

9. A mixture accordirg to any one of claims 1 to 7, including; a first portion in a range of 10% to 30% by weight of the mixture of first beads having a specific gravity in the range 5-9 and a mesh size in the range of 80-325; and a second portion in a range of 60% to 80% by weight of the mixture of second S C;\WINWORDKYUE\VARIOUS ODELP70 661 .DOC II beads having a specific gravity in the range of 2-3 and a mesh size in the range of 20-40 and having a third portion in the range of 5% to 15% by weight of the mixture of a partitioning and lubricating particulate material having a specific gravity in the range of 2-3 and a mesh size in the range of 20-325.

10. A mixture according to any one of claims 1 to 7, including; a first portion in a range of 10% to 30% by weight of the mixture of first beads having a specific gravity in the range 5-9 and a mesh size in the range of 80-325; and a second portion in a range of 60% to 80% by weight of the mixture of second beads having a specific gravity of 2-3 and a mesh size in the range of 20-40 and having a third portion in the range of 5% to 15% by weight of the mixture a partitioning and lubricating particulate material having a specific gravity in the range of 2-3 and a mesh size in the range of 20-325 and having a fourth portion in the range of 1% to 5% by weight of the mixture of a desiccating particulate matter of a mesh size in the range of 20-40.

11. A mixture according to any one of claims 1 to 7, including; a first ii portion in a range of 15% to 30% by weight of the mixture of first beads of atomized metallic micro-spheres having a specific gravity in the range 5-9 and a mesh size in the range of 80-325; and a second portion in a range of 70% to of the mixture of second beads of glass having a specific gravity of 2-3 and a mesh size in the range of 20-40.

12. A mixture according to any one of claims 1 to 7, including; a first portion in a range of 10% to 30% by weight of the mixture of first beads of atomized metallic micro-spheres having a specific gravity in the range 5-9 and a mesh size in the range of 80-325; and a second portion in a range of 50% to by weight of the mixture of second beads of glass having a specific gravity of 2-3 and a mesh size in the range of 20-40 and having a third portion in the range of to 15% by weight of the mixture of vermiculate having a specific gravity in the range of 2-3 and a mesh size in the range of 20-325.

13. A mixture according to any one of claims 1 to 7, including; a first portion in a range of 10% to 30% by weight of the mixture of first beads of atomized metallic micro-spheres having a specific gravity in the range 5-9 and a mesh size in the range of 80-325; and a second portion in a range of 60% to O:\WINWORDKyUE VARIOU- 0DEL\PT0661.DOC by weight of the mixture of second beads of glass having a specific gravity of 2-3 and a mesh size in the range of 20-40 and having a third portion in the range of to 15% by weight of the mixture of vermiculate having a specific gravity in the range of 2-3 and a mesh size in the range of 20-325 and having a fourth portion in the range of 1% to 5% by weight of the mixture of silica gel oi a mesh size in the range of 20-40.

14. A mixture according to any one of claims 1 to 7, including by weight; atomized metallic micro-spheres in the range from 15% to 20% of the mixture, glass spheres in the range of 65% to 75% of the mixture, vermiculite in the range of 7% to 12% of the mixture, silica gel in the range of 2% to t 'ixture. A mixture according to any one of claims 1 to 7, oy weight; 17% atomized metal selected from brass, bronze or zinc, 70% glass beads of lead-free soda lime glass, 10% vermiculite and 3% silica gel.

16. A mixture according to any one of claims 1 to 7, including atomized metallic micro-spheres in the range of 20% to 30% by weight of the mixture by weight, glass beads in the range of 60% to 70%, vermiculite in the range of 5% to 12%, silica gel in the range of 1% to 3%.

17. A mixture according to any one of claims 1 to 7, including by weight; 24% of atomized metallic micro-spheres selected from brass, bronze or zinc, S 20 of glass beads of lead-free soda lime glass, 9% of vermiculite and 2% of silica gel.

18. A method for balancing a tire rim assembly including the steps of, providing a tire rim assembly having a hollow tire casing surrounding a space about the rim, said space to be filled and pressurized with air; 25 the invention including pouring a mixture into the interior of the tire casing, said mixture including a first weight portion of solid beads having a first density and a first size and a second weight portion of solid beads having a secoiid density and a second size wherein said first portion is smaller than said second portion, said first density is grater than said second density and said first size is smaller than said second size; and C.AWINWORO\KYUE VARIOUSNCODELP7O66OOC; rotating the tire rim assembly to distribute the material within the tire casing to offset forces of imbalance.

19. A method according to claim 18 in which the mixture includes a first portion in a range of 15% to 30% by weight of the mixture of first beads having a specific gravity in the range 5-9 and a mesh size in the range of 80-325; and a second portion in a range of 70% to 85% by weight of the mixture of second beads having a specific gravity in the range of 2-3 and a mesh size in the range of 20-40. A method according to claim 18 in which the mixture includes a first portion in a range of 10% to 30% by weight of the mixture of first beads having a specific gravity in the range 5-9 and a mesh size in the range of 80-325; and a second portion in a range of 60% to 80% by weight of the mixture of second beads having a specific gravity in the range of 2-3 and a mesh size in the range of 20-40 and having a third portion in the range of 5% to 15% by weight of the mixture of a partitioning and lubricating particulate material having a specific gravity in the range of 2-3 and a mesh size in the range of 20-325.

21. A method according to claim 18 in which the mixture includes a first portion in a range of 10% to 30% by weight of the mixture of first beads having a specific gravity in the range 5-9 and a mesh size in the range of 80-325; and a second portion in a range of 60% to 80% by weight of the mixture of second beads having a specific gravity of 2-3 and a mesh size in the range of 20-40 &nd having a third portion in the range of 5% to 15% by weight of the mixture a 0 partitioning and lubricating particulate miterial having a specific gravity in the 0** range of 2-3 and a mesh size in the range of 20-325 and having a fourth portion 25 in the range of 1% to 5% by weight of the mixture of a desiccating particulate 0 0 matter of a mesh size in the range of 20-40.

22. A method according to claim 18 in which the mixture includes a first portion in a range of 15% to 30% by weight of the mixture of first beads of atomized metallic micro-spheres having a specific gravity in the range 5-9 and a mesh size in the range of 80-325; and a second portion in a range of 70% to by weight of the mixture of second beads of glass having a specifiu gravity of 2-3 and a mesh size in the range of 20-40. 'C WINWcRD(IE\VARIOUS\NODEL\P7661.DOC 11

23. A method according to claim 18 in which the mixture includes a first portion in a range of 10% to 30% by weight of the mixture of first beads of atomized metallic micro-spheres having a specific gravity in the range 5-9 and a mesh size in the range of 80-325; and a second portion in a range of 60% to by weight of the mixture of second beads of glass having a specific gravity of 2-3 and a mesh size in the range of 20-40 and having a third portion in the range of to 15% by weight of the mixture of vermiculate having a specific gravity in the range of 2-3 and a mesh size in the range of 20-325.

24. A method according to claim 18 in which the mixture includes a first portion in a range of 10% to 30% by weight of the mixture of first beads of atomized metallic micro-spheres having a specific gravity in the range of 5-9 and a mesh size in the range of 80-325; and a second portion in a range of 60% to by weight of the mixture of second beads of glass having a specific gravity of 2-3 and a mesh size in the range of 20-40 and having a third portion in the range of 5% to 15% by weight of the mixture of vermiculate having a specific gravity in the range of 2-3 and a mesh size in the range of 20-325 and having a fourth portion in the range of 1% to 5% by weight of the mixture of silica gel of a mesh size in the range of 20-40.

25. A method according to claim 18 in whiO-; the tire is a truck tire and said mixture includes by weight; atomized metallic micro-spheres in the range from 15% to 20% of the mixture, glass spheres in the range of 65% to 75% of the mixture, vermiculite in the range of 7% to 12% of the mixture, silica gel in the o range of 2% to 4% of the mixture.

26. A method according to claim 18 in which he tire is a truck tire and 25 said mixture includes by weight; 17% atomized metal selected from brass, bronze or zinc, 70% glass beads of lead-free soda lime glass, 10% vermiculite and 3% silica gel.

27. A method according to claim 18 in which the tire is an automobile tire and said mixture includes by weight atomized metallic micro-spheres in the range of 20% to 30% of The mixture by weight, glass beads in the range of 60% to vermiculite in the range of 5% to 12%, silica gel in the range of 1% to 3%. C\W1NWORODYUEXVAFlOUSNODELPO66.DOC I' 12

28. A method according to claim 18 in which the tire is an automobile tire and said mixture includes by weight; 24% of atomized metallic micro-spheres selected from brass, bronze or zinc, 65% of glass beads of lead-free soda lime glass, 9% of vermiculite and 2% of silica gel.

29. A mixture of material for balancing a tire substantially as herein before described and illustrated. A method for balancing a tire substantially as herein before described and illustrated. DATE: 4 July, 1997 PHILLIPS ORMONDE FITZPATRICK Attorneys for: M R TIRE PRODUCTS INC 9. o S o 4 *6 C:%WINWORD KYLIE\VAOUS\N"OEL\P7O66OlDOC