Self-pumping vent holes for cooling solid rubber tire and method of construction

A solid rubber tire with a multiplicity of self-pumping vent holes formed into opposed spaced apart sidewalls of the solid rubber tire. The self-pumping vent holes each extend from the side walls into the solid rubber tire about one-half the spaced apart distance and parallel to the rotation axis of the tire. Each of the multiplicity of self-pumping vent holes has a maximum cross-sectional dimension of between 0.5% and 1.5% of the maximum tire diameter. Any and all parts of the solid rubber material in the tire are at a distance of less than 12% of the original maximum diameter of the tire from any one of the multiplicity of self-pumping vent holes so that heat that may result in the solid rubber tire from its use is dissipated and temperature of the rubber in the tire is reduced by pumping of air into and out of the multiplicity of self-pumping vent holes upon rolling contact with the ground.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to solid rubber tires of the type that may be bonded to wheels of vehicles and in particular to tire and wheel assemblies for heavy construction equipment.

2. Background Art

Solid rubber tires with a plurality of cushioning holes have been used on heavy construction equipment as shown in U.S. Pat. No. 7,174,934 to Giles A. Hill, III et al., the applicants herein, issued Feb. 13, 2007. Such tires have been constructed with side holes formed in the shapes of cylinders into the sidewalls of the tires oriented generally parallel with the axis of rotation and the diameters of the side holes were typically in the range of between about 1.5 inches and 6 inches in diameter to provide good cushioning with relatively few holes made into the solid rubber of the tire. A plurality of cushioning side holes were formed in several rings all closely spaced at small tire radii from the axis of rotation close to the wheel rim and spaced circumferentially around the rings at regular distances. The cylindrical cushioning holes were formed at the small tire radii inward from a wear layer of the tire to avoid wearing into the holes. Wearing into the cushioning holes could result in an uneven rolling surface due to the significant diameter of the voids that would be created by the cylindrical holes if the tread layer wore through. Thus, the wear layer of solid rubber extended a significant distance outward from the cushioning holes. In the past such solid rubber tires with cushioning holes have functioned well and have provided both cushioning and durability for the intended purposes in industrial environments of daily use.

SUMMARY OF INVENTION

It has been discovered by the applicants that in certain situations solid rubber tires have been called upon to operate substantially continuously 24 hours every day. For example, in a multiple shift industrial environment where separate operators of the vehicle runs the solid rubber tires during consecutive 8 hour shifts, substantially without any long period of discontinued use. According to one embodiment of the invention, it has been discovered by the inventors that excessive heat build-up in the wear layer of the solid rubber tire for heavy construction equipment can lead to accelerated deterioration and premature wear-out of the tire. It has been discovered that in environments of substantially continuous use without sufficient periods of non-use to allow dissipation of the excessive heat, a solid rubber tire with a built in cooling mechanism can reduce the heat build up in the tire and thereby reduce premature deterioration of the solid rubber tire.

According to one or more embodiment, a solid rubber tire is provided with a multiplicity of self-pumping vent holes formed into opposed spaced apart sidewalls of the solid rubber tire. The self-pumping vent holes each extend from the side walls into the solid rubber tire about one-half the spaced apart distance and generally parallel to the rotation axis of the tire. Each of the multiplicity of self-pumping vent holes has rounded cross-sectional shape and a maximum cross-sectional dimension of between 0.5% and 1.5% of the maximum tire diameter. The multiplicity of self-pumping vent holes are spaced from each other so that all of the solid rubber material forming the tire is at a distance of less than about 12% of the maximum diameter of the tire from any one of the multiplicity of self-pumping vent holes. Any excessive heat that may result in the solid rubber tire from its rolling use may be reduced by pumping of air into and out of the multiplicity of self-pumping vent holes upon rolling contact with the ground.

According to one or more embodiment, a solid rubber tire is provided with a multiplicity of self-pumping vent holes formed into opposed spaced apart sidewalls of the solid rubber tire. The self-pumping vent holes each extend from the side walls into the solid rubber tire about one-half the spaced apart distance and generally parallel to the rotation axis of the tire. According to one embodiment the multiplicity of self-pumping vent holes are formed in a plurality of rings at regularly spaced radii that extend into the wear layer of the tire to within a distance of within 12% of the maximum tire diameter of the wear layer so that the maximum space of any rubber in the wear layer is less than about 12% of the maximum diameter of the tire. The self pumping vent holes have rounded cross-sectional shapes and a maximum cross-sectional dimension of between 0.5% and 1.5% of the maximum tire diameter so that wearing into the vent holes does not create a significant void relative to the diameter of the tire. The multiplicity of self-pumping vent holes are spaced from each other so that all of the solid rubber material forming the tire is at a distance of less than about 12% of the maximum diameter of the tire from any one of the multiplicity of self-pumping vent holes. Any excessive heat that may result in the solid rubber tire from its rolling use may be reduced by pumping of air into and out of the multiplicity of self-pumping vent holes upon rolling contact with the ground.

According to one or more embodiments a solid rubber tire is provided with a multiplicity of self-pumping vent holes formed into opposed spaced apart sidewalls of the solid rubber tire, wherein each of the multiplicity of self-pumping vent holes has rounded cross-sectional shape and a maximum cross-sectional dimension of between about one-half inch (0.5 inch) and one and one fourth inches (1.25 inches). The multiplicity of self-pumping vent holes are spaced from each other so that all of the solid rubber material forming the tire, including the wear layer, is at a distance of less than about 9 inches from any one of the multiplicity of self-pumping vent holes. Any excessive heat that may result in the solid rubber tire from its rolling use may be reduced by pumping of air into and out of the multiplicity of self-pumping vent holes upon rolling contact with the ground.

DETAILED DESCRIPTION

FIG. 1shows a prior art solid rubber tire1with pluralities of cushioning holes2,3,4, and5formed in a sidewall6of the tire1. The holes are formed adjacent a rim7positioned in a ring having a small radius “r” that is less than about 80% of the maximum tire radius “R”. The maximum distance “d” from any of the holes2,3,4, or5to rubber in the tire tread is greater than abut 20% (i.e. d/R>20%).

FIG. 2shows a solid rubber tire10according to one or more embodiments of the invention with a multiplicity of self-pumping vent holes generally referred to with reference arrow20and specifically referred to with reference numbers21a-x,22a-x,23a-x,24a-x,25a-x, and26a-x(where the number represents a ring sometimes referred to as a row of self pumping vent holes and the subscripts a-x represent a sequence of holes) formed into one side wall12of the solid rubber tire10. The plurality of self pumping vent holes21a-xare formed spaced apart in a ring is formed in a ring pattern. Similarly, a multiplicity of self-pumping vent holes41a-x,42a-x,43a-x,44a-x,45a-x, and46a-x(not shown in the side view ofFIG. 2, seeFIG. 3) are formed into another side wall14opposed to and spaced apart from sidewall12. In the embodiment shown there are 24 holes in each ring however it will be understood that the number of holes required to meet the spacing requirements for self pumping vent hole cooling according to certain aspects of the invention may be different. For example larger tires may require a greater number of holes and smaller tires might require fewer holes. The self-pumping vent holes20each extend from the side walls into the solid rubber tire about one-half the spaced apart distance and generally parallel to the rotation axis of the tire. Each of the multiplicity of self-pumping vent holes has rounded cross-sectional shape and a maximum cross-sectional dimension “h” of between about 0.5% and 1.5% of the maximum tire diameter “D” (i.e., about 0.5%<h/D<about 1.5%). The multiplicity of self-pumping vent holes21a-x,22a-x,23a-x,24a-x,25a-x, and26a-xand41a-x,42a-x,43a-x,44a-x,45a-x, and46a-x(not shown) are spaced from each other so that all of the solid rubber material forming the tire is at a distance “d” of less than about 12% of the maximum diameter D of the tire from any one of the multiplicity of self-pumping vent holes. Any excessive heat that may result in the solid rubber tire10from its rolling use may be reduced by pumping of air into (at52) and pumping air out of (at54) the multiplicity of self-pumping vent holes21a-x,22a-x,23a-x,24a-x,25a-x, and26a-xand41a-x,42a-x,43a-x,44a-x,45a-x, and46a-x(not shown) upon rolling contact of the tire10at56with the ground58.

InFIG. 3, a partial cross-section shows a plurality of self pumping vent holes generally by arrows20and40and specifically as21,22,23,24,25, and16in side wall12of tire10and41,42,43,44,45, and46formed into side wall14of tire10. In one embodiment as shown the plurality of vent holes20and40extend into the tire10from opposed sides12and14, respectively. They are positioned generally parallel to the axis36of rotation for the rim30and the solid rubber tire10mounted thereon. The vent holes20and40may extend inward in a range of from close to the midline38to overlapping as depicted inFIG. 3. While extending to close to the midline (wherein the plurality of vent holes extend into the tire to a maximum depth that is less than half the distance between the side walls of the tire) can meet the objective of vent holes within a short distance of all parts of the sold rubber tire for cooling of the rubber, overlapping (wherein the plurality of vent holes extend into the tire to maximum depth more than half the distance between the side walls of the tire) as shown in this embodiment can usefully provide additional cooling from the deepest parts of the solid rubber tire to facilitate cooling air flow from the depth of the vent holes. In one or more embodiments the internal rubber parts11of the tire are at a distance from the maximum depth of the vent holes that is less than about 12% of the original maximum tire diameter. In one or more embodiments as shown inFIG. 3, the vent holes may comprise hollow tubular holes21-25and41-46wherein the rounded cross sectional shape, viewed in the direction of wheel axis36has a smaller diameter at the deepest part (i.e., adjacent to a midline38between the sidewalls12and14as shown) and a larger diameter at the side walls12and14of the tire10.

InFIG. 4an alternative embodiment is depicted of a tire10and rim30assembly, with example dimensions given in inches for forming rings of self pumping vent holes20. In this embodiment there are rings of holes at six different radii or diameters 21 (47.5 inches), 22 (51.0 inches), 23 (54.5 inches), 24 (58.0 inches), 25 (61.5 inches) and 26 (65.0 inches). In each ring there are a plurality of holes at regular angular spacing.

FIG. 5shows the front view and example dimensions of the tire ofFIG. 4, for example, the tire diameter D 75.05 inches), the tire width (30 inches) and the tire midline (15 inches).

FIG. 6shows a rim30onto which a tire10is molded according to one or more embodiments of the invention, including for example, the diameter (44.0 inches) and the width (30.0 inches).

FIG. 7shows an example of a pin28useful for forming one of the plurality of vent holes20or40. A plurality of pins28are secured to opposed sides in a tire mold (not shown) and the solid rubber is molded and vulcanized in the desired shape and size the tire and with the pins28embedded therein. In one or more embodiments the plurality of vent holes comprise hollow tubular holes wherein the rounded cross sectional shape comprises a non-circular rounded shape and in one or more embodiments the plurality of vent holes comprise hollow tubular holes wherein the rounded cross sectional shape comprises a circular rounded shape. As an example, for a tire as inFIG. 4orFIG. 6, a total length (18.25 inches), and changing diameter along a length (17.5 inches), where the diameter varies along the length according to the example shown inFIG. 7(1.0 inch at top at28a, tapered to 0.5 inch at28b, and tapered to 0.41 inch at28cand to a pointed tip at28d). The mold and the pins28are removed as by pulling opposed sides of the mold apart and the self pumping vent holes remain as voids in the vulcanized rubber16of the tire10. The self pumping vent holes formed in the outermost ring or at the largest radius are closest to the outermost parts of the solid rubber16of the tire10. The maximum distance d from any one of the holes to any part of the rubber16is relatively close so that a cooling gradient can be maintained.

In the embodiment depicted inFIG. 4, the solid rubber16located in the outermost diameter of the tire10appear to be at a farthest distance from any of the self pumping vent holes20. The vent holes in the ring of vent holes designated26are at a maximum distance “d” from the outermost portion of the solid rubber tire. All other parts of the solid rubber16, according to the dimensions indicated in this exampleFIG. 4are, a shorter distance from at least one of the vent holes20. Based upon calculation the distance d for this useful example embodiment of the invention are less than about 9 inches and in particular are less than about 12% of the maximum diameter D of the tire10(calculated as follows: d/D<0.12). In this embodiment, therefore, all other parts of the solid rubber tire, including the internal parts11of the tire10are at a distance from the maximum depth of the vent holes that is less than about 12% of the original maximum tire diameter D.

FIG. 8is an example of results obtained in a test tires for testing the theoretical cooling concept of self pumping vent holes according to one embodiment of the invention. Temperature measurements are in degrees F. With six rows of vent holes the tires were cooler by 50 degrees F. compared to prior art tires that had failed at 240 degrees at the tread. In this test the heat build up appeared to be in the middle part of the solid rubber, at the 3rd, 4thand 5thrings of vent holes where the vent holes closest to the rim were designated the 1st row and the outermost ring of vent holes was designated the 6throw. The 6throw, i.e., adjacent to the tire tread was at temperature of 183 F, significantly lower than the 240 F temperature of prior art tires that failed.

FIG. 9is a partial side view of a solid rubber tire11with self pumping vent holes wherein the outer tread surface layer of rubber of the tire11is partially worn off and into one ring26of self pumping vent holes26a, b, c, . . . x. The small diameters of the rounded vent holes26a, b, c, . . . x, usefully allows the tire to wear into the vent holes without causing large voids in the rolling tread surface. Rather the small diameter (0.5% to 1.5% of the tire diameter) means that the void is smaller or no larger than the amount of compression for purpose of pumping or no larger than a typical traction indentation for tread of other types of tires.

FIG. 11is a perspective view showing an embodiment of a process for making a solid rubber tire with self-pumping vent holes. The process depicted inFIG. 11comprises forming an uncured solid rubber material70into a generally cylindrically shaped solid rubber tire72around a central tire axis74and opposed side walls76, and78spaced apart a distance from each other measured in a direction approximately parallel to the tire axis74and the opposed side walls76,78extending from an interior diameter82outward to an outer diameter84of the cylindrically shaped solid rubber tire70. A tire mold assembly90is formed having a mold cavity92and a mold closure94. The mold cavity comprises a generally cylindrical rim96having a maximum interior diameter98around a central axis100and a first side102closing the mold cavity92at one end and the closure94having a second side106for closing the mold cavity92at the other end so that the closed cavity92and closure94form a cylinder with an inside diameter98and sides102and104spaced apart a distance80in the axial direction when they are assembled together. A first plurality of pins110(see side view of one embodiment of a pin28inFIG. 7) are formed attached to the side102in the mold cavity92in a spaced apart pattern (seeFIG. 4) with each of the plurality of pins110spaced from each other a distance that is no greater than about 12% of the maximum inside diameter98of the cylindrical mold rim in one embodiment and no greater than about 9 inches in another embodiment. Each pin110having a rounded cross-section with a maximum dimension of between about 0.5% and 1.2% of the maximum inside cylindrical rim diameter in one embodiment and between about 0.5 inch and 1.25 inches in another embodiment. The pins110extend from the side102into the cavity92in a direction generally parallel to the axis100of the rim.

A second plurality of pins112are formed attached to the side104of the mold closure94in a spaced apart pattern with each of the plurality of pins112spaced from each other a distance that is no greater than about 12% of the maximum inside diameter of the cylindrical mold rim in one embodiment and no greater than about 9 inches in another embodiment. Each pin112having a rounded cross-section with a maximum dimension of between about between about 0.5 inch and 1.25 in one embodiment and extending from the side104of the closure94in a direction toward the cavity92side102generally parallel to the central axis100of the rim and extending a distance of about one-half of the distance between the cavity side102and the closure side104of the mold when the mold cavity assembly is closed together. The formed uncured rubber cylindrically shaped of the solid tire70is placed partially into the mold cavity92with the tire axis84generally aligned with the mold cavity axis100. The mold closure94is placed in axial alignment with the mold cavity and with the uncured rubber cylindrically shaped solid tire70. The closure94and mold cavity92are pressed together so that the pins110and112penetrate into the opposed sides72and78of the uncured rubber, cylindrically shaped solid tire material70. The closure and mold cavity are held together with pressure and the uncured rubber cylindrically shaped solid tire70is heated and vulcanized in an autoclave, a with the solid rubber tire thereby molded in the cylindrical shape of the mold cavity92with the pins110and114penetrated into the sides72and78of the rubber tire. The closure94and pins112are removed and the cured solid rubber tire is removed from the cavity92and from the pins110so that vent holes each having a rounded cross-section with a maximum dimension of between about 0.5% and 1.2% of the maximum inside cylindrical rim diameter in one embodiment, and between about 0.5 inch and 1.25 inches in another embodiment, are formed in the opposed sides72and78of the vulcanized solid rubber tire.

According to one embodiment a solid rubber tire is disclosed for bonding to a wheel for rolling use on a vehicle. The solid rubber tire comprises a solid rubber material formed into a cylindrically shaped tire about a tire rotation axis including an interior surface for bonding to the wheel, an exterior tread surface at a maximum tire diameter, and opposed side walls spaced apart distance from each other side wall in a direction parallel to the rotation axis and extending from the interior surface to the exterior tread surface. A multiplicity of self-pumping vent holes are formed into the opposed spaced apart sidewalls of the solid rubber tire extending from each of the side walls into the solid rubber tire about one-half the spaced apart distance and substantially parallel to the rotation axis of the tire, and each of the multiplicity of self-pumping vent holes having a rounded cross-sectional shape and a maximum cross-sectional dimension of between about one-half inch (0.5 inch) and one and one fourth inches (1.25 inches) and each of the multiplicity of self-pumping vent holes spaced from each other of the self-pumping vent holes so that all of the solid rubber material in the tire is at a distance of less than about 9 inches from any one of the multiplicity of self-pumping vent holes, wherein any heat that may result in the solid rubber tire from rolling use of the tire is reduced by pumping of air into and out of the multiplicity of self-pumping vent holes upon rolling contact of the tire with the ground.

According to one embodiment the plurality of vent holes in the solid rubber tire extend into the tire less than half the distance between the sidewalls of the tire.

According to one embodiment the plurality of vent holes in the solid rubber tire extend into the tire more than half the distance between the sidewalls of the tire.

According to one embodiment the plurality of vent holes in the solid rubber tire comprise a cylindrical shape wherein the rounded cross sectional shape comprises a circular shape.

According to one embodiment, the plurality of vent holes in the solid rubber tire comprise hollow tubular holes wherein the rounded cross sectional shape comprises a non-circular shape.FIG. 10shows a partial side view of an embodiment of a solid rubber tire17with a plurality of self pumping vent holes19having a non circular rounded cross-sectional shape according to one alternative embodiment of the invention.

According to one embodiment a method of making a solid rubber tire is disclosed. The method includes forming an uncured solid rubber material into a generally cylindrically shaped solid rubber tire around a central tire axis and opposed side walls spaced apart a distance from each other measured in a direction approximately parallel to the tire axis and the opposed side walls extending from an interior diameter outward to an outer diameter of the cylindrically shaped solid. The method includes forming a tire mold having a mold cavity and a mold closure, the mold cavity comprising a generally cylindrical rim having a maximum interior diameter around a central axis and a first side closing the mold cavity at one end and the closure having a side for closing the mold cavity at the other end so that closed cavity and closure form a cylinder with an inside diameter and sides spaced apart a distance in the axis direction. The method includes forming a first plurality of pins attached to the side in the mold cavity in a spaced apart pattern with each of the plurality of pins spaced from each other so that no space between the pins is at a distance greater than about 9 inches from a pin, each pin having a rounded cross-section with a maximum dimension of between about 0.5% and 1.2% of the maximum inside cylindrical rim diameter and extending from the side into the cavity in a direction generally parallel to the axis of the rim. The method includes forming a second plurality of pins attached in a spaced apart pattern to the side of the mold closure in a spaced apart pattern with each of the plurality of pins spaced from each other so that no space is a distance from a pin that is greater than about 9 inches, each pin having a rounded cross-section with a maximum dimension of between about 0.5 inch and 1.25 and extending from the side of the closure in a direction toward the cavity side generally parallel to the central axis of the rim and extending a distance of about one-half of the distance between the cavity side and the closure side of the mold when the mold cavity is closed. The method includes placing the formed uncured rubber, cylindrically shaped solid tire partially into the mold cavity with the tire axis generally aligned with the mold cavity axis. The method includes placing the mold closure in axial alignment with the mold cavity and the uncured rubber cylindrically shaped solid tire. The method includes pressing the closure and mold cavity molded together so that the pins penetrate into the opposed sides of the uncured rubber, cylindrically shaped solid tire material. The method includes holding the closure and mold cavity together with pressure, heating the uncured rubber cylindrically shaped solid tire in an autoclave, and vulcanizing the solid rubber tire in the cylindrical shape of the mold cavity with the pins penetrated into the sides of the rubber tire. The method includes removing the closure and pins and removing the cured solid rubber tire from the cavity and pins so that vent holes each having a rounded cross-section with a maximum dimension of between about 0.5 inch and 1.25 inches are formed in the sides of the opposed sides of the vulcanized solid rubber tire.

According to one embodiment a method of making a solid rubber tire is disclosed wherein forming a first and second plurality of pins attached in spaced apart patterns to the side in the mold cavity and to the side of the mold closure, respectively, comprises attachment of circular cross sectional shaped pins wherein the maxim cross sectional dimension is the diameter of the circular cross-section of the pins.

While the invention has been described with respect to a limited number of embodiments, and the discussion has focused on specific embodiments of solid rubber tires, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. For example, differently shaped cross-section of the vent holes may also provide the benefits of self pumping of cooling air in to and out of the solid rubber tire as described without departing from the present invention. Accordingly, the scope of the invention should be limited only by the attached claims.