Patent Description:
The pneumatic tire has been the solution of choice for vehicular mobility for over a century. The pneumatic tire is a tensile structure. The pneumatic tire has at least four characteristics that make the pneumatic tire so dominant today. Pneumatic tires are efficient at carrying loads, because all of the tire structure is involved in carrying the load. Pneumatic tires are also desirable because they have low contact pressure, resulting in lower wear on roads due to the distribution of the load of the vehicle. Pneumatic tires also have low stiffness, which ensures a comfortable ride in a vehicle. The primary drawback to a pneumatic tire is that it requires compressed gasses. A conventional pneumatic tire is rendered useless after a complete loss of inflation pressure.

A tire designed to operate without inflation pressure may eliminate many of the problems and compromises associated with a pneumatic tire. Neither pressure maintenance nor pressure monitoring is required. Structurally supported tires such as solid tires or other elastomeric structures to date have not provided the levels of performance required from a conventional pneumatic tire. A structurally supported tire solution that delivers pneumatic tire-like performance would be a desirous improvement.

Non pneumatic tires are typically defined by their load carrying efficiency. "Bottom loaders" are essentially rigid structures that carry a majority of the load in the portion of the structure below the hub. "Top loaders" are designed so that all of the structure is involved in carrying the load. Top loaders thus have a higher load carrying efficiency than bottom loaders, allowing a design that has less mass.

The purpose of the shear band is to transfer the load from contact with the ground through tension in the spokes or connecting web to the hub, creating a top loading structure. When the shear band deforms, its preferred form of deformation is shear over bending. The shear mode of deformation occurs because of the inextensible membranes located on the outer portions of the shear band. Prior art non-pneumatic tire typically has a shear band made from rubber materials sandwiched between at least two layers of inextensible belts or membranes. The disadvantage to this type of construction is that the use of rubber significantly increases the cost and weight of the non-pneumatic tire. Another disadvantage to the use of rubber is that is generates heat, particularly in the shear band. Furthermore, the rubber in the shear band needs to be soft in shear, which makes it difficult to find the desired compound.

Thus, an improved non-pneumatic tire is desired that has all the features of the pneumatic tires without the drawback of the need for air inflation is desired.

<CIT> and <CIT> describe a non-pneumatic tire in accordance with the preamble of claim <NUM>.

<CIT> describes a shear band with two rubber layers. <CIT> shows a shear band with only a first and second layer of fabric.

The invention relates to a tire in accordance with claim <NUM>.

Dependent claims refer to preferred embodiment of the invention.

The present invention will be better understood through reference to the following description and the appended drawings, in which:.

The following terms are defined as follows for this description.

"Auxetic material" means a material that has a negative Poisson's ratio.

"Cord" means the twisted fiber or filament of, for instance, polyester, rayon, nylon or steel, which form a reinforcement cord.

"Equatorial Plane" means a plane perpendicular to the axis of rotation of the tire passing through the centerline of the tire.

"Fabric" means a network of cords which extend in in multiple directions.

"Free area" is a measure of the openness of the fabric per DIN EN <NUM> and is the amount of area in the fabric plane that is not covered by yarn. It is a visual measurement of the tightness of the fabric and is determined by taking an electronic image of the light from a light table passing through a <NUM> by <NUM> square sample of the fabric and comparing the intensity of the measured light to the intensity of the white pixels.

"Inextensible" means that a given layer has an extensional stiffness greater than <NUM> MPa (<NUM> Ksi).

"Knitted" is meant to include a structure producible by interlocking a series of loops of one or more yarns by means of needles or wires, such as warp knits and weft knits.

"Three-dimensional spacer structure" may mean a three-dimensional structure composed from two outer layers of fabric, each outer layer of fabric having reinforcement members (such as yarns, filaments or fibers) which extend in a first and second direction, wherein the two outer layers are connected together by reinforcement members (yarns, filaments or fibers) or other knitted layers that extend in a defined third direction. An "open" three-dimensional spacer structure comprises individual pile fibers or reinforcements that connect the first and second layer of fabric. A "closed" three-dimensional structure utilizes fabric piles that connect the first and second layers.

"Yarn" means a continuous strand of textile fibers or filaments. A monofilament yarn has only a single filament with or without twist.

"Woven" is meant to include a structure produced by multiple yarns crossing each other at right angles to form the grain, like a basket.

A first embodiment of a non-pneumatic tire <NUM> of the present invention is shown in <FIG>. The tire of the present invention includes a radially outer ground engaging tread <NUM>, a shear band <NUM>, and a connecting web <NUM>. The tire tread <NUM> may include elements such as ribs, blocks, lugs, grooves, and sipes as desired to improve the performance of the tire in various conditions. The connecting web <NUM> is mounted on a hub <NUM> and may have different designs, such as spokes or an elastomeric web. The non-pneumatic tire of the present invention is designed to be a top loading structure, so that the shear band <NUM> and the connecting web <NUM> efficiently carry the load. The shear band <NUM> and the connecting web are designed so that the stiffness of the shear band is directly related to the spring rate of the tire. The connecting web is designed to be a stiff structure when in tension that buckles or deforms in the tire footprint and does not compress or carry a compressive load. This allows the rest of the connecting web not in the footprint area the ability to carry the load, resulting in a very load efficient structure. It is desired to allow the shearband to bend to overcome road obstacles. The approximate load distribution is preferably such that approximately <NUM>-<NUM>% of the load is carried by the shear band and the upper portion of the connecting web, so that the lower portion of the connecting web carry virtually zero of the load, and preferably less than <NUM>%.

The shear band <NUM> is preferably an annular structure that is located radially inward of the tire tread <NUM>. The shear band includes a three-dimensional spacer structure <NUM>, shown in <FIG>. The three-dimensional spacer structure <NUM> may be positioned between a first and second layer of gum rubber <NUM>, <NUM> (not shown to scale). The gum rubber <NUM>, <NUM> may be as thick as desired.

As shown in <FIG> and in <FIG>, the three-dimensional spacer structure <NUM> is a type of structure that is formed of a first and second layer of fabric <NUM>, <NUM>, wherein each layer of fabric is formed from reinforcement members that may be knitted, woven, nonwoven, interlaced or non-interlaced. The reinforcement members are preferably multifilament and formed of polyester or nylon material. The first and second layers <NUM>, <NUM> of fabric are preferably oriented parallel with respect to each other and are interconnected with each other by a plurality of pile connecting members <NUM> that extend in a third or pile dimension. As shown in <FIG>, the pile connecting members <NUM> may form a straight connection of the first and second layers <NUM>, <NUM> that may extend in the radial direction or be angled with the radial direction. The pile connecting members <NUM> may form an X shape, or letter <NUM> shape or combinations thereof. The pile connecting members <NUM> are preferably monofilaments made of polyester material. <FIG> illustrates an exemplary three-dimensional spacer structure with a closely knit upper and lower fabric with pile reinforcement members in a closely spaced configuration. <FIG> illustrates an exemplary three-dimensional spacer structure with upper and lower fabric layers having a pattern of hexagonal shaped recesses formed with straight pile reinforcement members.

The perpendicular distance between the connecting layers <NUM>, <NUM> or Z direction dimension of the three-dimensional structure is preferably in the range of <NUM> millimeters to <NUM> millimeters, more preferably <NUM>-<NUM> millimeters, and even more preferably in the range of <NUM>-<NUM>.

The three-dimensional spacer structure <NUM> is preferably oriented in the shear band so that the first and second layers <NUM>, <NUM> are aligned in parallel relation and extend across the axial direction of the non-pneumatic tire, as well as extending in the circumferential direction. The pile reinforcement members <NUM> of three-dimensional fabric structure <NUM> are preferably aligned with the radial direction of the non-pneumatic tire.

As shown in <FIG>, the three-dimensional spacer structure has upper and lower fabric layers <NUM>, <NUM> that are each knitted or otherwise joined to a non-crimped fabric layer (NCF) <NUM>, <NUM> respectively. As shown in <FIG>, the NCF layer <NUM>, <NUM> is formed from two fiber layers <NUM>, <NUM> wherein the orientation of the fiber layers are selected for optimum performance. In this example, the fiber orientation of layers <NUM>, <NUM> are +<NUM> degrees and - <NUM> degrees. The invention is not limited to this fiber orientation, as other orientations may be utilized such as zero degree, <NUM> degree and in the range of <NUM> to <NUM> degrees. The NCF layers <NUM>, <NUM> are joined together with the lower layer of the three-dimensional spacer structure <NUM> by warp knitting as shown in <FIG>. The process is preferably repeated for the upper layer of the three-dimensional spacer structure <NUM>, so that the top and bottom layers <NUM>, <NUM> are each reinforced with a NCF layer <NUM>, <NUM>.

<FIG> illustrates a NCF layer having a bi-axial reinforcement structure with fiber layers <NUM>, <NUM> oriented perpendicular to each other and secured together with warp knitting yarn <NUM>. As compared to a woven fabric as shown in <FIG>, the NCF layer has highly aligned fibers without the undulations of the woven fabric. <FIG> illustrates that the NCF reinforcement layer <NUM> may comprise multiple layers, and as shown, includes an optional nonwoven layer <NUM>, a fiber layer <NUM> of <NUM> degrees, a fiber layer <NUM> of <NUM> degrees, a fiber layer <NUM> of -<NUM> degrees, and a fiber layer <NUM> of zero degrees that are all knitted together with a warp knitting yarn <NUM>. The angular orientations refer to the angle the fibers make with the tire circumferential plane. For example, a fiber orientation of zero degrees, means that the fibers are oriented in the circumferential direction, and <NUM> degrees are oriented perpendicular to the zero degree fibers and are aligned with the axial direction of the tire.

<FIG> and <FIG> illustrate a second embodiment of the shear band <NUM> of the present invention. The shear band <NUM> includes a three-dimensional spacer structure <NUM> that has an upper and lower fabric surface <NUM>, <NUM> that is knitted to a NCF fabric with a biaxial reinforcement structure <NUM>, wherein the fibers <NUM>, <NUM> are perpendicular to each other and oriented at zero degrees and <NUM> degrees with respect to the tire mid-circumferential plane.

Both the three-dimensional spacer fabric and the integrated NCF layer are coated with a skin layer <NUM> formed of rubber, urethane, polyurethane, or thermoplastic materials such as polypropylene, polyester terephthalates, polyamides, polyethylene, thermoplastic copolymers, and thermoplastic co-polyesters. The skin layer may be applied by spraying, brushing, stamping, 3D printing, liquid bath or other methods known to those skilled in the art.

The NCF layers as described above may be formed of glass fibers, carbon fibers or hybrid fibers combining glass and carbon fibers. The three-dimensional spacer structure may be additionally reinforced with cords or wires or combinations thereof. The resulting shear band composite structure is strong and ultralight and dispenses with the need for additional belt reinforcing layers or rubber shear layers.

Preferably, the three-dimensional fabric structure <NUM> is treated with an RFL adhesive prior to application of the skin layer, which is a well-known resorcinol-formaldehyde resin/butadiene-styrene-vinyl pyridine terpolymer latex, or a blend thereof with a butadiene/styrene rubber latex, that is used in the tire industry for application to fabrics, fibers and textile cords for aiding in their adherence to rubber components (for example, see <CIT>. ) The reinforcement members may be single end dipped members (i.e., a single reinforcement member is dipped in RFL adhesive or adhesion promoter.

Claim 1:
A non-pneumatic tire having an outer tread ring (<NUM>) and a shear band (<NUM>, <NUM>), wherein the shear band (<NUM>, <NUM>) includes a three-dimensional spacer structure (<NUM>, <NUM>) comprising a first and second layer of fabric (<NUM>, <NUM>), characterized in that the first and second layer of fabric (<NUM>, <NUM>) are connected to a respective first and second layer (<NUM>, <NUM>) of non-crimped fabric (<NUM>, <NUM>).