Patent Application
20050072504
The present invention is directed to a support ring for tires that operate in reduced air pressure conditions. More specifically, the support ring is provided with a metal mesh support located at the radially inner base of the ring.
Tires are primarily supported by internal air pressure. A number of tire designs now exist that use a support ring located inside the tire to support the tire when the tire is operated in an underinflated condition. The use of a support ring of annular shape made of a flexible elastomeric material has been known for a long time. To improve the endurance performance of the support, a lubricant is generally included inside the tire cavity in order to lubricate any contact there may be between the outer surface of the ring and the inside of the tire.
Internal support rings are disclosed in U.S. Pat. Nos. 4,248,286, 5,891,279, 6,463,972, and US Patent Application Publications US 2002/0157752 and US 2003/0005991. The rings are formed from either elastomeric or thermoplastic materials. The material selection is based upon the anticipated load the ring will be supporting.
An advantage of using thermoplastic material in forming the ring is the relatively lighter weight material and the flexibility of the material. However, because of the flexibility of the material, when the ring is formed from thermoplastics, the ring is subject to expansion due to centrifugal forces encountered while driving at high speeds. Similar expansion of the ring is also experienced when the ring is formed from elastomeric material. The present invention is directed at overcoming and eliminating this problem.
The inventive support ring is intended to be mounted on a wheel rim inside a tire, in order to support the tread strip of the tire in the event of reduced inflation pressure. The support has a contoured base intended to fit snugly around the wheel rim contour, a substantially cylindrical cap. In accordance with the invention, the base of the support ring is provided with a metal support.
The metal support has a mesh configuration, i.e., an open network configuration. The spaces forming the mesh may have a constant size and spacing but may vary in size and spacing either laterally or circumferentially along the inner surface of the support ring.
The support ring may be formed from any suitable material which can support the under-inflated tire during operation and which will remain viable for at least a distance which will enable the vehicle operator to have the tire examined, and fixed or repaired. The material may be elastomeric, thermoplastic, or thermoset.
The metal support may be formed of steel, aluminum, or other metallic material that will provide the desired tensile strength.
The metal support is spaced from the radially innermost surface of the ring by a distance of 0.10 to 10.0 mm.
The invention will be described by way of example and with reference to the accompanying drawings in which:
The wheel rim 12 is a one-piece wheel. The wheel rim 12 comprises axially, starting from the same side as the wheel disk 18, namely from the side intended to be on the outboard side of the vehicle: a first seat 20, a flat cylindrical region 22 intended to receive the support ring 10, the diameter of this region 22 is greater than that of the seat 20 to allow the support ring to be mounted easily and directly by slipping it on axially, a stop 24 for the transverse immobilization of the support ring 10, a mounting well 26, this well 26 is of minimized size by comparison with conventional mounting wells, a second seat 28 preceded by a retaining hump 30, the diameter of this second seat is greater than the diameter of the region 22. One feature of this wheel rim is that the two seats 20, 28 are angled in the opposite direction to the seats of conventional wheel rims.
The illustrated tire 16 is an asymmetric tire and has two beads 32 of differing diameters. The tire may be provided with a lenticular shaped inserts in the tire sidewalls to aid in supporting the tire during under inflated operating conditions. Such inserts, and other similar inserts, are well known in the art.
The support ring 10 has three main parts: a base 34 of annular overall shape, a substantially annular cap 36 with grooves in accordance with the present invention, and an annular body 38 for joining the base 34 and the cap 36 together. The annular body 38 may have any configuration desired to achieve a particular set of design characteristics.
The support ring 10 is formed from elastomeric, thermoplastic, or thermoset materials. If the support ring 10 is formed of elastomeric material, such as natural rubber, the elastomer should have a Shore A hardness of 60 to 90. If the support ring 10 is formed of a material such as polyurethane, polyester elastomers, or nylon, than the material should have a Shore D hardness of 30 to 45.
Within the base 34 of the ring 10, in accordance with the invention, is a metal support 40. The metal support 40 is configured as a mesh, see
The mesh configuration provides flexibility to the metal support 40. A small degree of flexibility is necessary for removing the ring 10 from the mold after formation and for mounting the ring 10. The metal forming the support 40 provides strength and a necessary degree of rigidity to prevent excessive expansion of the ring 10 during operation.
The openings 42 of the mesh allow the material forming the ring 10 to penetrate through the metal support 40 and encase it within the ring base 34. The metal support 40 is located substantially near the innermost surface of the ring 10, and is distanced from the innermost surface by a distance x. The distance x is in the range of 0.10 to 10 mm, but in no circumstance is the distance x greater than the thickness y of the base. Preferably, the distance x is the range of 5 to 75% of the thickness y, more preferably in the range of 5 to 45% of the thickness y.
The support 40 may be formed as a unitary circle or may be welded into a circular configuration after forming of the mesh.
As noted, the presence of the metal mesh prevents expansion of the ring 10 due to centrifugal forces.
Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full-intended scope of the invention as defined by the following appended claims.
