Non-pneumatic tire and other annular devices

A non-pneumatic tire for a vehicle or other machine. The non-pneumatic tire may include an annular beam. The annular beam may include a plurality of layers of different elastomeric materials. The annular beam may be free of a substantially inextensible reinforcing layer running in a circumferential direction of the non-pneumatic tire. The annular beam may include a plurality of openings distributed in the circumferential direction of the non-pneumatic tire. Such an annular beam may be part of other annular devices.

FIELD

The invention generally relates to non-pneumatic tires (NPTs), such as for vehicles (e.g., industrial vehicles such as construction vehicles; all-terrain vehicles (ATVs); agricultural vehicles; automobiles and other road vehicles; etc.) and/or other machines, and to other annular devices.

BACKGROUND

Wheels for vehicles and other machines may comprise non-pneumatic tires (sometimes referred to as NPTs) instead of pneumatic tires.

Pneumatic tires are market leaders across a wide variety of size, speed, and load requirements. For example, radial pneumatic tires are found on automotive tires of 0.6 meter diameter that carry 0.5 metric tons, and also on tires used in mining operations of 4 meter diameter that carry 50 metric tons. Pneumatic tires are thus scalable.

Pneumatic tires offer high load capacity per unit mass, along with a large contact area and relatively low vertical stiffness. High contact area results in the ability to both efficiently generate high tangential forces and obtain excellent wear characteristics. However, pneumatic tires are also prone to flats.

Non-pneumatic tires offer flat-free operation, yet generally contain some compromise. For various reasons, non-pneumatic tires do not have a predominant market share in various industries because they tend to be expensive, heavy, have a poor ride quality, have limited speed capability under heavy load, and/or have lower traction potential, compared to pneumatic tires. For example, in construction and other field with large tires, in the common dimension 20.5 inch×25 inch (20.5 inches wide, 25 inch diameter wheel), currently available non-pneumatic tires weighs around 2000 lbs., whereas a pneumatic tire and steel wheel only weigh around 650 lbs.

Non-pneumatic tires in this size are usually solid, with the addition of circular cutouts in the tire sidewall to reduce the compressive stiffness of the structure. Because of this solid construction, heat build-up is problematic. Elastomers are generally good insulators, and therefore such structures tend to retain heat. This reduces their utility in practical use in some cases.

Other annular devices, such as, for instance, tracks for vehicles and/or conveyor belts, may in some cases be affected by similar considerations.

For these and other reasons, there is a need to improve non-pneumatic tires and other annular devices.

SUMMARY

According to an aspect of the invention, there is provided a non-pneumatic tire comprising an annular beam. The annular beam comprises a plurality of layers of different elastomeric materials. The annular beam is free of a substantially inextensible reinforcing layer running in a circumferential direction of the non-pneumatic tire.

According to another aspect of the invention, there is provided a wheel comprising a hub and a non-pneumatic tire. The non-pneumatic tire comprises an annular beam. The annular beam comprises a plurality of layers of different elastomeric materials. The annular beam is free of a substantially inextensible reinforcing layer running in a circumferential direction of the non-pneumatic tire.

According to another aspect of the invention, there is provided an annular beam comprising a plurality of layers of different elastomeric materials. The annular beam is free of a substantially inextensible reinforcing layer running in a circumferential direction of the annular beam.

According to another aspect of the invention, there is provided a method of making a non-pneumatic tire. The method comprises providing a plurality of different elastomeric materials and forming an annular beam of the non-pneumatic tire such that the annular beam comprises a plurality of layers of the different elastomeric materials and is free of a substantially inextensible reinforcing layer running in a circumferential direction of the non-pneumatic tire.

According to another aspect of the invention, there is provided a method of making an annular beam. The method comprises providing a plurality of different elastomeric materials and forming the annular beam such that the annular beam comprises a plurality of layers of the different elastomeric materials and is free of a substantially inextensible reinforcing layer running in a circumferential direction of the annular beam.

According to another aspect of the invention, there is provided a non-pneumatic tire comprising an annular beam. The annular beam comprises a plurality of layers of different elastomeric materials. The annular beam comprises a plurality of openings distributed in a circumferential direction of the non-pneumatic tire.

According to another aspect of the invention, there is provided a wheel comprising a hub and a non-pneumatic tire. The non-pneumatic tire comprises an annular beam. The annular beam comprises a plurality of layers of different elastomeric materials. The annular beam comprises a plurality of openings distributed in a circumferential direction of the non-pneumatic tire.

According to another aspect of the invention, there is provided an annular beam. The annular beam comprises a plurality of layers of different elastomeric materials. The annular beam comprises a plurality of openings distributed in a circumferential direction of the annular beam.

According to another aspect of the invention, there is provided a method of making a non-pneumatic tire. The method comprises providing a plurality of different elastomeric materials and forming an annular beam of the non-pneumatic tire such that the annular beam comprises a plurality of layers of the different elastomeric materials and a plurality of openings distributed in a circumferential direction of the non-pneumatic tire.

According to another aspect of the invention, there is provided a method of making an annular beam. The method comprises providing a plurality of different elastomeric materials and forming the annular beam such that the annular beam comprises a plurality of layers of the different elastomeric materials and a plurality of openings distributed in a circumferential direction of the annular beam.

According to another aspect of the invention, there is provided a wheel comprising a hub and a non-pneumatic tire. A ratio of a width of the non-pneumatic tire over an outer diameter of the non-pneumatic tire is no more than 0.1 and a ratio of a diameter of the hub over the outer diameter of the non-pneumatic tire is no more than 0.5.

According to another aspect of the invention, there is provided a wheel comprising a hub and a non-pneumatic tire. A ratio of a length of a contact patch of the non-pneumatic tire at a design load over an outer radius of the non-pneumatic tire is at least 0.4

According to another aspect of the invention, there is provided a non-pneumatic tire comprising an annular beam and a tread. The annular beam is free of a substantially inextensible reinforcing layer running in a circumferential direction of the non-pneumatic tire. The tread comprises elastomeric material and a reinforcing layer disposed within the elastomeric material and extending in the circumferential direction of the non-pneumatic tire.

These and other aspects of the invention will now become apparent to those of ordinary skill in the art upon review of the following description of embodiments of the invention in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1shows an example of a vehicle10comprising a plurality of wheels1001-1004in accordance with an embodiment of the invention. In this embodiment, the vehicle10is an industrial vehicle. The industrial vehicle10is a heavy-duty vehicle designed to travel off-road to perform industrial work using a work implement44. In this embodiment, the industrial vehicle10is a construction vehicle for performing construction work using the work implement44. More particularly, in this embodiment, the construction vehicle10is a loader (e.g., a skid-steer loader). The construction vehicle10may be a bulldozer, a backhoe loader, an excavator, a dump truck, or any other type of construction vehicle in other embodiments. In this example, the construction vehicle10comprises a frame12, a powertrain14, a steering system16, a suspension18, the wheels1001-1004, and an operator cabin22, which enable a user, i.e., an operator, of the construction vehicle10to move the vehicle10on the ground and perform work using the work implement44. The construction vehicle10has a longitudinal direction, a widthwise direction, and a height direction.

In this embodiment, as further discussed later, the wheels1001-1004are non-pneumatic (i.e., airless) and may be designed to enhance their use and performance and/or use and performance of the construction vehicle10, including, for example, by having a high load-carrying capacity while being relatively lightweight.

The powertrain14is configured for generating motive power and transmitting motive power to respective ones of the wheels1001-1004to propel the construction vehicle10on the ground. To that end, the powertrain14comprises a prime mover26, which is a source of motive power that comprises one or more motors. For example, in this embodiment, the prime mover26comprises an internal combustion engine. In other embodiments, the prime mover26may comprise another type of motor (e.g., an electric motor) or a combination of different types of motor (e.g., an internal combustion engine and an electric motor). The prime mover26is in a driving relationship with one or more of the wheels1001-1004. That is, the powertrain14transmits motive power generated by the prime mover26to one or more of the wheels1001-1004(e.g., via a transmission and/or a differential) in order to drive (i.e., impart motion to) these one or more of the wheels1001-1004.

The steering system16is configured to enable the operator to steer the construction vehicle10on the ground. To that end, the steering system16comprises a steering device28that is operable by the operator to direct the construction vehicle10along a desired course on the ground. The steering device28may comprise a steering wheel or any other steering component (e.g., a joystick) that can be operated by the operator to steer the construction vehicle10. The steering system16responds to the operator interacting with the steering device28by turning respective ones of the wheels1001-1004to change their orientation relative to part of the frame12of the construction vehicle10in order to cause the vehicle10to move in a desired direction. In this example, a front frame member231carrying front ones of the wheels1001-1004is turnable in response to input of the operator at the steering device28to change its orientation and thus the orientation of the front ones of the wheels1001-1004relative to a rear frame member232of the construction vehicle10in order to steer the construction vehicle10on the ground.

The suspension18is connected between the frame12and the wheels1001-1004to allow relative motion between the frame12and the wheels1001-1004as the construction vehicle10travels on the ground. For example, the suspension18may enhance handling of the construction vehicle10on the ground by absorbing shocks and helping to maintain traction between the wheels1001-1004and the ground. The suspension18may comprise an arrangement of springs and dampers. A spring may be a coil spring, a leaf spring, a gas spring (e.g., an air spring), or any other elastic object used to store mechanical energy. A damper (also sometimes referred to as a “shock absorber”) may be a fluidic damper (e.g., a pneumatic damper, a hydraulic damper, etc.), a magnetic damper, or any other object which absorbs or dissipates kinetic energy to decrease oscillations. In some cases, a single device may itself constitute both a spring and a damper (e.g., a hydropneumatic, hydrolastic, or hydragas suspension device).

The operator cabin22is where the operator sits and controls the construction vehicle10. More particularly, the operator cabin22comprises a user interface70including a set of controls that allow the operator to steer the construction vehicle10on the ground and operate the work implement44. The user interface70also comprises an instrument panel (e.g., a dashboard) which provides indicators (e.g., a speedometer indicator, a tachometer indicator, etc.) to convey information to the operator.

The wheels1001-1004engage the ground to provide traction to the construction vehicle10. More particularly, in this example, the front ones of the wheels1001-1004provide front traction to the construction vehicle10while the rear ones of the wheels1001-1004provide rear traction to the construction vehicle10.

Each wheel100icomprises a non-pneumatic tire110for contacting the ground and a hub120for connecting the wheel100ito an axle of the vehicle10. The non-pneumatic tire110is a compliant wheel structure that is not supported by gas (e.g., air) pressure and that is resiliently deformable (i.e., changeable in configuration) as the wheel100icontacts the ground. With additional reference toFIG. 2, the wheel100ihas an axial direction defined by an axis of rotation180of the wheel100i(also referred to as a “Y” direction), a radial direction (also referred to as a “Z” direction), and a circumferential direction (also referred to as a “X” direction). These axial, radial and circumferential directions also apply to components of the wheel100i, including the non-pneumatic tire110. The wheel's equatorial plane is that plane defined by the x-z axes, while the wheel's cross section is that plane defined by the y-z axes. The wheel100ihas an outer diameter DWand a width WW. It comprises an inboard lateral side147for facing a center of the vehicle in the widthwise direction of the vehicle and an outboard lateral side149opposite the inboard lateral side147. As shown inFIG. 3, when it is in contact with the ground, the wheel100ihas an area of contact125with the ground, which may be referred to as a “contact patch” of the wheel100iwith the ground. The contact patch125of the wheel100i, which is a contact interface between the non-pneumatic tire110and the ground, has a length LCin the circumferential direction of the wheel100iand a width WCin the axial direction of the wheel100i.

The non-pneumatic tire110comprises an annular beam130and an annular support140that is disposed between the annular beam130and the hub120of the wheel100iand configured to support loading on the wheel100ias the wheel100iengages the ground. In this embodiment, the non-pneumatic tire110is tension-based such that the annular support140is configured to support the loading on the wheel100iby tension. That is, under the loading on the wheel100i, the annular support140is resiliently deformable such that a lower portion127of the annular support140between the axis of rotation180of the wheel100iand the contact patch125of the wheel100iis compressed and an upper portion129of the annular support140above the axis of rotation180of the wheel100iis in tension to support the loading.

The annular beam130of the non-pneumatic tire110is configured to deflect under the loading on the wheel100iat the contact patch125of the wheel100iwith the ground. In this embodiment, the annular beam130is configured to deflect such that it applies a homogeneous contact pressure along the length LCof the contact patch125of the wheel100iwith the ground.

More particularly, in this embodiment, the annular beam130comprises a shear band131configured to deflect predominantly by shearing at the contact patch125under the loading on the wheel100i. That is, under the loading on the wheel100i, the shear band131deflects significantly more by shearing than by bending at the contact patch125. The shear band131is thus configured such that, at a center of the contact patch125of the wheel100iin the circumferential direction of the wheel100i, a shear deflection of the annular beam130is significantly greater than a bending deflection of the annular beam130. For example, in some embodiments, at the center of the contact patch125of the wheel100iin the circumferential direction of the wheel100i, a ratio of the shear deflection of the annular beam130over the bending deflection of the annular beam130may be at least 1.2, in some cases at least 1.5, in some cases at least 2, in some cases at least 3, in some cases at least 5, in some cases at least 7, and in some cases even more. For instance, in some embodiments, the annular beam130may be designed based on principles discussed in U.S. Patent Application Publication 2014/0367007, which is hereby incorporated by reference herein, in order to achieve the homogeneous contact pressure along the length LCof the contact patch125of the wheel100iwith the ground.

In this embodiment, the shear band131of the annular beam130comprises a plurality of layers1321-132Nof different elastomeric materials M1-ME. The layers1321-132Nof the different elastomeric materials M1-MEextend in the circumferential direction of the wheel100iand are disposed relative to one another in the radial direction of the wheel100i. As further discussed later, in some embodiments, this laminate construction of the different elastomeric materials M1-MEmay enhance performance of the wheel100i, including behavior of its contact patch125and may also help the annular beam130to have a high load to mass ratio, yet keep the simplicity of an elastomer structure, with no need for inextensible membranes or other composites or reinforcing elements. In this example, the layers1321-132Nof the different elastomeric materials M1-MEare seven layers, namely the layers1321-1327and the different elastomeric materials M1-MEare two different elastomeric materials, namely the elastomeric materials M1, M2. The layers1321-132Nand/or the elastomeric materials M1-MEmay be present in any other suitable numbers in other examples.

More particularly, in this embodiment, the layers1321,1323,1325and1327are made of the elastomeric material M1while the layers1322,1324and1326are made of the elastomeric material M2and are disposed between respective ones of the layers1321,1323,1325and1327made of the elastomeric material M1. The layers1321-1327of the annular beam130are thus arranged such that the different elastomeric materials M1, M2 alternate in the radial direction of the wheel100i.

For instance, in this embodiment, the shear band131comprises the layer1321, composed of elastomeric material M1, lying on a radially inward extent of the shear band131. The shear band131comprises the layer1322, composed of elastomeric material M2, lying on a radially outward extent of the layer1321. The shear band131comprises the layer1323, composed of elastomeric material M1, lying on a radially outward extent of the layer1322. In this embodiment, a laminate configuration of the elastomeric material of the shear band131is M1/M2/M1. In other embodiments, the laminate configuration of the elastomeric material of the shear band131may be repeated any number of times. For example, inFIGS. 4 and 5, the laminate configuration of the elastomeric material of the shear band131from an inward to an outward extent of the shear band131is M1/M2/M1/M2/M1/M2/M1. Each one of the layers1321-1327is composed of a homogeneous elastomer in this example.

The different elastomeric materials M1and M2may differ in any suitable way. For example, in some embodiments, a stiffness of the elastomeric material M1may be different from a stiffness of the elastomeric material M2. That is, the elastomeric material M1may be stiffer or less stiff than the elastomeric material M2. For instance, a modulus of elasticity E1(i.e., Young's modulus) of the elastomeric material M1may be different from a modulus of elasticity E2of the elastomeric material M2. A modulus of elasticity herein is Young's tensile modulus of elasticity measured per ISO 527-1/-2, and “Young's Modulus,” “tensile modulus,” and “modulus” may be used interchangeably herein. For example, in some embodiments, the modulus of elasticity E1of the elastomeric material M1may be greater than the modulus of elasticity E2of the elastomeric material M2. For instance, in some embodiments, a ratio E1/E2of the modulus of elasticity E1of the elastomeric material M1over the modulus of elasticity E2of the elastomeric material M2may be at least 2, in some cases at least 3, in some cases at least 4, in some cases at least 5, in some cases at least 6, in some cases at least 7, in some cases at least 8, and in some cases even more.

For example, in some embodiments, the modulus of elasticity E1of the elastomeric material M1may be at least 150 MPa, and in some cases at least 200 MPa or even more, while the modulus of elasticity E2of the elastomeric material M2may be no more than 50 MPa, and in some cases no more than 30 MPa or even less. As will be disclosed, such a modulus definition can be engineered to give a beam particular bending and shear properties that are favorable for use in the non-pneumatic tire110.

FIG. 5shows a cross section AA of the shear band131of the annular beam130where the layers1321-1327of the annular beam131are shown. In some embodiments, such as the embodiment ofFIGS. 4 and 5, the innermost layer1321and the outermost layer1327of the shear band131may be composed of the elastomeric material M1with the modulus of elasticity E1higher than the modulus of elasticity E2of the elastomeric material M2. That is, in this embodiment, the elastomeric material with the higher modulus of elasticity may be used at the inner and outer radial extents of the shear band131of the annular beam130.

In other embodiments, other repeating or non-repeating laminate configurations of the elastomeric material of the shear band131comprising the elastomeric material with the higher modulus of elasticity at the inner and outer radial extents of the shear band131may be used. That is, in these embodiments, multiple layers composed of multiple elastomeric materials may be used with or without symmetry of the laminate configuration of the elastomeric material of the shear band131and the shear band131may comprise at least three elastomeric materials in a laminate configuration. For example, the laminate configuration of the elastomeric material of the shear band131from an inward to an outward extent of the shear band131may be of the type M1/M2/M3/M2/M1or M1/M2/M3/M1or any other combination thereof, where M3is an elastomeric material having a modulus of elasticity E3different from the modulus of elasticity E1of the elastomeric material M1and different from the modulus of elasticity E2of the elastomeric material M2.

In some embodiments, and with further reference toFIGS. 4 and 5, each one of the layers1321-1327of the shear band131extends from the inboard lateral side147to the outboard lateral side149of the non-pneumatic tire110. That is, each one of the layers1321-1327of the shear band131extends laterally through the shear band131in the axial direction of the wheel100.

The different elastomeric materials M1-MEmay include any other suitable elastomers in various embodiments. For example, in some embodiments, suitable elastomeric materials include thermoplastic and thermoset polyurethane and thermoplastic and thermoset rubbers.

In this embodiment, the annular beam130is free of (i.e., without) a substantially inextensible reinforcing layer running in the circumferential direction of the wheel100i(e.g., a layer of metal, composite (e.g., carbon fibers, other fibers), and/or another material that is substantially inextensible running in the circumferential direction of the wheel100i). In that sense, the annular beam130may be said to be “unreinforced”. Thus, in this embodiment, useful behavior of the wheel100i, including deflection and behavior of its contact patch125, may be achieved without any substantially inextensible reinforcing layer running in the circumferential direction of the wheel100i, which may help to reduce the weight and cost of the wheel100i.

In this embodiment, the non-pneumatic tire110comprises a tread150for enhancing traction between the non-pneumatic tire110and the ground. The tread150is disposed about an outer peripheral extent146of the annular beam130, in this case about the outermost layer1327of the shear band131composed of the elastomeric material M1. More particularly, in this example the tread150comprises a tread base151that is at the outer peripheral extent146of the annular beam130and a plurality of tread projections1521-152Tthat project from the tread base151. The tread150may be implemented in any other suitable way in other embodiments (e.g., may comprise a plurality of tread recesses, etc.).

The annular support140is configured to support the loading on the wheel100ias the wheel100iengages the ground. As mentioned above, in this embodiment, the annular support140is configured to support the loading on the wheel100iby tension. More particularly, in this embodiment, the annular support140comprises a plurality of support members1421-142Tthat are distributed around the non-pneumatic tire110and resiliently deformable such that, under the loading on the wheel100i, lower ones of the support members1421-142Tin the lower portion127of the annular support140(between the axis of rotation180of the wheel100iand the contact patch125of the wheel100i) are compressed and bend while upper ones of the support members1421-142Tin the upper portion129of the annular support140(above the axis of rotation180of the wheel100i) are tensioned to support the loading. As they support load by tension when in the upper portion129of the annular support140, the support members1421-142Tmay be referred to as “tensile” members.

In this embodiment, the support members1421-142Tare elongated and extend from the annular beam130towards the hub120generally in the radial direction of the wheel100i. In that sense, the support members1421-142Tmay be referred to as “spokes” and the annular support140may be referred to as a “spoked” support.

More particularly, in this embodiment, each spoke142iextends from an inner peripheral surface148of the annular beam130towards the hub120generally in the radial direction of the wheel100iand from a first lateral end155to a second lateral end157in the axial direction of the wheel100i. In this case, the spoke142iextends in the axial direction of the wheel100ifor at least a majority of a width WTof the non-pneumatic tire110, which in this case corresponds to the width WWof the wheel100i. For instance, in some embodiments, the spoke142imay extend in the axial direction of the wheel100ifor more than half, in some cases at least 60%, in some cases at least 80%, and in some cases an entirety of the width WTof the non-pneumatic tire110. Moreover, the spoke142ihas a thickness TSmeasured between a first surface face159and a second surface face161of the spoke142ithat is significantly less than a length and width of the spoke142i.

When the wheel100iis in contact with the ground and bears a load (e.g., part of a weight of the vehicle), respective ones of the spokes1421-142Tthat are disposed in the upper portion129of the spoked support140(i.e., above the axis of rotation180of the wheel100i) are placed in tension while respective ones of the spokes1421-142Tthat are disposed in the lower portion127of the spoked support140(i.e., adjacent the contact patch125) are placed in compression. The spokes1421-142Tin the lower portion127of the spoked support140which are in compression bend in response to the load. Conversely, the spokes1421-142Tin the upper portion129of the spoked support140which are placed in tension support the load by tension.

The spokes1421-142Tmay be implemented in any other suitable way in other embodiments. For example,FIGS. 6 to 9show various embodiments of the design of the spokes1421-142T. In the embodiment ofFIG. 6, each spoke142iextends generally along a straight line in the radial direction of the wheel100i. In the embodiment ofFIG. 7, each spoke142iextends generally along a straight line in the radial direction of the wheel100i, a spoke connector143being located between every other pair of successive spokes142iand connecting two successive spokes142i. The spoke connector143is substantially perpendicular to the radial direction of the wheel100iand may be positioned at any distance from the hub120. along the radial direction of the wheel100i. In some embodiment, the spoke connector143extends in the axial direction of the wheel100ifor at least a majority of the width WTof the non-pneumatic tire110, which in this case corresponds to the width WWof the wheel100i. For instance, in some embodiments, the spoke connector143may extend in the axial direction of the wheel100ifor more than half, in some cases at least 60%, in some cases at least 80%, and in some cases an entirety of the width WTof the non-pneumatic tire110. Moreover, the spoke connector143has a thickness TSCmeasured between a first surface face163and a second surface face165of the spoke connector143that is significantly less than a length and width of the spoke connector143. In other embodiments, the spoke connector143may not be substantially perpendicular to the radial direction of the wheel100i. In other embodiments, there may be a plurality of spoke connectors143connecting two spokes142i. In the embodiment ofFIG. 8, each spoke142iextends generally along a straight line at an angle α or −α in the radial direction of the wheel100isuch that two successive spokes142ido not extend generally along a straight line at the same angle in the radial direction of the wheel100i. In the embodiment ofFIG. 9, each spoke142iextends generally as a curved line along the radial direction of the wheel100i. Other designs may be possible in other embodiments.

The non-pneumatic tire110has an inner diameter DTIand an outer diameter DTO, which in this case corresponds to the outer diameter DWof the wheel100. A sectional height HTof the non-pneumatic tire110is half of a difference between the outer diameter DTOand the inner diameter DTIof the non-pneumatic tire110. The sectional height HT of the non-pneumatic tire may be significant in relation to the width WTof the non-pneumatic tire110. In other words, an aspect ratio AR of the non-pneumatic tire110corresponding to the sectional height HTover the width WTof the non-pneumatic tire110may be relatively high. For instance, in some embodiments, the aspect ratio AR of the non-pneumatic tire110may be at least 70%, in some cases at least 90%, in some cases at least 110%, and in some cases even more. Also, the inner diameter DTIof the non-pneumatic tire110may be significantly less than the outer diameter DTOof the non-pneumatic tire110as this may help for compliance of the wheel100i. For example, in some embodiments, the inner diameter DTIof the non-pneumatic tire110may be no more than half of the outer diameter DTOof the non-pneumatic tire110, in some cases less than half of the outer diameter DTOof the non-pneumatic tire110, in some cases no more than 40% of the outer diameter DTOof the non-pneumatic tire110, and in some cases even a smaller fraction of the outer diameter DTOof the non-pneumatic tire110.

In this embodiment, the non-pneumatic tire110therefore comprises different tire materials that make up the tire110, including the elastomeric materials M1-MEof the shear band131of the annular beam130and a spoke material145that makes up at least a substantial part (i.e., a substantial part or an entirety) of the spokes1421-142T. The hub120comprises a hub material172that makes up at least a substantial part of the hub120. In some embodiments, the hub material172may be the same as one of the tire materials, namely one of the elastomeric materials M1-MEof the shear band131of the annular beam130and the spoke material145. In other embodiments, the hub material172may be different from any of the tire materials, i.e., different from any of the elastomeric materials M1-MEof the shear band131of the annular beam130and the spoke material145. For instance, in some embodiments, the spoke material145and the hub material172may be any one of the elastomeric material M1, M2, M3or any other elastomeric material that may be comprised in the shear band131of the annular beam130.

In this embodiment, any given material of the wheel100i, such as any given one of the tire materials (i.e., the elastomeric materials M1-MEof the shear band131of the annular beam130and the spoke material145) and/or the hub material172may exhibit a non-linear stress vs. strain behavior. For instance, the spoke material145may have a secant modulus that decreases with increasing strain of the spoke material145. A secant modulus herein is defined as a tensile stress divided by a tensile strain for any given point on a tensile stress vs. tensile strain curve measured per ISO 527-1/-2. The spoke material145may have a high Young's modulus that is significantly greater than the secant modulus at 100% strain (a.k.a. “the 100% modulus”). Such a non-linear behavior of the spoke material145may provide efficient load carrying during normal operation and enable impact loading and large local deflections without generating high stresses. For instance, the spoke material145may allow the non-pneumatic tire110to operate at a low strain rate (e.g., 2% to 5%) during normal operation yet simultaneously allow large strains (e.g., when the wheel100iengages obstacles) without generating high stresses. This in turn may be helpful to minimize vehicle shock loading and enhance durability of the non-pneumatic tire110.

The non-pneumatic tire110may comprise any other arrangement of materials in other embodiments (e.g., different parts of the annular beam130, different parts of the tread150, and/or different parts of the spokes1421-142Tmay be made of different materials). For example, in some embodiments, different parts of the tread150, and/or different parts of the spokes1421-142Tmay be made of different elastomers.

In this embodiment, the hub material172constitutes at least part of the hub120. More particularly, in this embodiment, the hub material172constitutes at least a majority (e.g., a majority or an entirety) of the hub120. In this example of implementation, the hub material172makes up an entirety of the hub120.

In this example of implementation, the hub material172is polymeric. More particularly, in this example of implementation, the hub material172is elastomeric. For example, in this embodiment, the hub material172comprises a polyurethane (PU) elastomer. For instance, in some cases, the PU elastomer may be PET-95A commercially available from COIM, cured with MCDEA.

The hub material172may be any other suitable material in other embodiments. For example, in other embodiments, the hub material172may comprise a stiffer polyurethane material, such as COIM's PET75D cured with MOCA. In some embodiments, the hub material172may not be polymeric. For instance, in some embodiments, the hub material172may be metallic (e.g., steel, aluminum, etc.).

The hub120may comprise one or more additional materials in addition to the hub material172in other embodiments (e.g., different parts of the hub120may be made of different materials).

For example, in some embodiments, for the spoked support140and the hub120, various cast polyurethanes of either ether or ester systems may be used when appropriate (e.g. with alternative cure systems such as MOCA). In some examples, a shore hardness in the range of 90 A to 75 D and/or a Young's modulus between 40 MPA to 2000 MPa may be appropriate.

In some embodiments, the spoked support140and the hub120may comprise different materials. For example, the spoked support140may comprise a softer material (e.g., with a Young's modulus between 40 MPA to 100 MPA) and the hub120may comprise a harder material (e.g., with modulus between 300 to 2000 MPA).

The tread150may comprise an elastomeric material160. In some examples of implementation, the elastomeric material160of the tread150may be different from the elastomeric materials M1-MEof the annular beam130. For example, in some embodiments, the elastomeric material160of the tread150may be rubber. In other embodiments, the elastomeric material160of the tread150may be polyurethane or another elastomer. For instance, in some embodiments, the tread150may comprise rubber, cast polyurethane or any other suitable elastomer, and may have a Shore hardness of between 60 A to 85 A, with a Young's modulus between 3 MPa and 20 MPa. The tread150may be provided in any suitable way, such as by molding and/or adhesively bonding the elastomeric material160of the tread150about the annular beam130.

The wheel100imay be manufactured in any suitable way. For example, in some embodiments, the non-pneumatic tire110and/or the hub120may be manufactured via centrifugal casting, a.k.a. spin casting, which involves pouring one or more materials of the wheel100iinto a mold200that rotates about an axis202as shown inFIG. 10. The material(s) is(are) distributed within the mold200via a centrifugal force generated by the mold's rotation. In some cases, vertical spin casting, in which the mold's axis of rotation202is generally vertical, may be used. In other cases, as shown inFIG. 10, horizontal spin casting, in which the mold's axis of rotation202is generally horizontal, may be used. In some embodiments, horizontal spin casting may be useful for casting the layers1321-132Nof the different elastomeric materials M1-MEof the annular beam130in a more controlled manner. The wheel100may be manufactured using any other suitable manufacturing processes in other embodiments.

The wheel100imay be lightweight. That is, a mass MWof the wheel100imay be relatively small. For example, in some embodiments, a ratio Mnormalizedof the mass MWof the wheel100iin kilograms over the outer diameter DWof the wheel100inormalized by the width WWof the wheel100i,

Mnormalized=(MwDw)Ww
may be no more than 0.00035 kg/mm2, in some cases no more than 0.00030 kg/mm2, in some cases no more than 0.00025 kg/mm2, in some cases no more than 0.00020 kg/mm2, in some cases no more than 0.00015 kg/mm2, in some cases no more than 0.00013 kg/mm2, in some cases no more than 0.00011 kg/mm2, and in some cases even less (e.g., no more than 0.0001 kg/mm2).

For instance, in some embodiments, the outer diameter of the wheel100imay be 1.5 m, the width of the wheel100imay be about 0.5 m, and the mass MWof the wheel100may be about 336 kg. The load capacity of the wheel100imay be about 10,000 kg at 15 kph. The wheel100imay be a replacement for a 20.5″×25″ pneumatic tire.

The wheel100i, including the non-pneumatic tire110and the hub120, may thus be designed to enhance its use and performance. Notably, in some embodiments, the structure of the shear band131of the annular beam130comprising the different elastomeric materials M1-MEin a laminate configuration may be related to the deflection properties of the annular beam130so as to enhance behavior of the contact patch125of the wheel100i. When connected to the hub120via the spokes1421-142T, the annular beam130has a high load to mass ratio, yet keeps the simplicity of an elastomer structure, with no need for inextensible membranes or other composites or reinforcing elements.

For example, in some embodiments, a tire contact pressure may be substantially constant along the length LCof the contact patch125. To achieve this, the annular beam130having a radius of curvature R may be designed such that it develops a relatively constant pressure along the length LCof the contact patch125when the annular beam130is deformed to a flat surface. With reference toFIGS. 11 and 12, this is analogous to designing a straight beam which deforms to a circular arc of radius R when subjected to a constant pressure which is equal to the contact pressure of the annular beam130along the length LCof the contact patch125. The inventor has found that a homogeneous beam of solid cross section does not behave like this. To create this desired performance, beam bending stiffness and beam shear stiffness can be designed using a laminate of elastomer materials, such that the beam deforms primarily in shear. An example of a method for doing so will now be discussed, using standard nomenclature (e.g. see for example Muvdi, B. B., McNabb, J. W., (1980). Engineering Mechanics of Materials, Macmillan Publishing Co., Inc., New York, N.Y., “Shear and Bending Moment in Beams,” pp 23-31, and “Deflections of Beams”, pp 266-333, which is hereby incorporated by reference herein).

Without wishing to be bound by any theory, it may be useful to consider certain aspects of the physics of elastomers. The relationship of shear force variation to an applied distributed load on a differential beam element can be expressed as follows:

-dVdx=W(1)
Where:V=transverse shear forceW=Constant distributed load per unit lengthx=beam length coordinate

The deflection of the differential beam element due to shear deformation alone can be estimated by combining Equation 1 with other known relationships. Adding relations between shear force, shear stress, shear modulus, and cross-sectional area, Equation 2 can be derived:

Shear modulus means the shear modulus of elasticity and is calculated according to Equation 10 below. For small deflections,

d2⁢zd2⁢x
is equal to the inverse of the deformed beam radius of curvature. Making this substitution and considering a beam of unit depth, one obtains Equation 3:

P=GAR(3)
Where:G=beam shear modulusR=deformed beam radius of curvatureA=effective beam cross sectional area, with unit depthP=Constant distributed pressure, with unit depth

According to equation 3, a straight beam of shear modulus G and effective cross sectional area A, such as the straight beam ofFIG. 11, will deform into the shape of an arc of radius R when subjected to homogeneous pressure P, provided shear deflection predominates.

Similarly, the annular beam130having radius of curvature R, designed such that shear deformation predominates, will develop a homogeneous contact pressure P along the contact patch125having the length LCwhen deflected against a flat contact surface.

A constant pressure along the contact patch125having the length LCmay be a highly desired performance attribute. It may be particularly useful when embodied in the non-pneumatic tire110ofFIGS. 1 to 3. With further reference toFIG. 3, when a design load is applied at the hub120, for instance when the wheel100isupports the weight of the vehicle10, the annular beam130deforms over the contact patch125having the length LCand develops a homogeneous contact pressure over the length LCof the contact patch125. The design load is a usual and expected operating load of the non-pneumatic tire110. Lower ones of the support members1421-142Tin the lower portion127of the annular support140(between the axis of rotation180of the wheel100and the contact patch125of the wheel100) are compressed and bend while upper ones of the support members1421-142Tin the upper portion129of the annular support140(above the axis of rotation180of the wheel100) are tensioned to support the loading, such that the annular beam130passes the load to the central hub120via tension in annular support140.

In some embodiments, a homogeneous contact pressure over the length LCof the contact patch125may be achieved through an appropriate laminate configuration of the shear band131of the annular beam130that comprises elastomers, such as the layers1321-132Nof the different elastomeric materials M1-ME. The material properties of the laminate configuration of the shear band131may be designed such that shear deflection can be larger than bending deflection at a center of the contact patch125.

Analysis of a straight beam may be less cumbersome than the analysis of an annular beam such as the annular beam130; therefore a first part of an example of a design process may employ a straight beam geometry such as the one shown inFIG. 12subjected to a constant pressure, in order to design the laminate configuration of the annular beam130and the thickness of each one of the layers1321-132Nof the different elastomeric materials M1-MEin the laminate configuration of the annular beam130. Final design verification may then include a complete tire model, as will be discussed. Accordingly, in this example, the first step in developing a design process is to calculate the deflection due to bending and the deflection due to shear of a simply supported straight beam subjected to a constant pressure, as shown inFIG. 12. Equation 4 gives the center deflection due to bending; Equation 5 gives the center deflection due to shear; Equation 6 solves for shear deflection divided by bending deflection:

zb=5384⁢PL4EI(4)zs=14⁢PL2GA(5)zszb=19.2⁢EIL2⁢1GA(6)
Where:zb=beam center deflection due to bendingzs=beam center deflection due to shearL=beam length, which is about equal to the length Lcof the contact patch125E=beam tensile modulusI=beam moment of inertia

The result of Equation (6) is a dimensionless geometrical term that, for homogeneous materials, is independent of modulus. As zs/zbbecomes larger, shear deflection predominates. As shear deflection predominates, Equation (3) becomes valid and the desired performance of a constant pressure through the length LCof the contact patch125is achieved.

In usual engineering calculation of transverse deflection of beams, shear deflection may be assumed to be small compared to bending deflection, and shear deflection may be neglected. Consequently, the result of Equation (6) may not be commonly considered. Beam bending stiffness must be relatively high, and beam shear stiffness must be relatively low in order to have zs/zbbe high enough so that Equation (3) becomes approximately valid.

The next step of the design process in this example is to define the procedure to relate the design of the elastomer laminate structure to the terms of Equation 6. Analytical solutions for the terms are provided below.

FIG. 11uses a laminate configuration equivalent to the laminate configuration of the shear band131of the annular beam130as shown inFIGS. 4 and 5. For illustrative purposes, this cross section definition will be used to demonstrate an example of a design methodology. Using the same technique, any general laminate elastomer cross section can be analyzed to determine the quantities for Equation 6.

With reference toFIG. 11an effective beam shear modulus for this cross-section may be estimated to be used as G in Equation 6. This is calculated using Equation 7:

The effective shear modulus calculation is used as the shear modulus G in Equation (5) to calculate zs, the beam center deflection due to shear. For a unit depth assumption the effective beam cross sectional area A for shear deformation calculation equals the beam shear thickness tshear. Thus:
A=tshear(8)

Physically, this can be visualized as the shear deflection across the web of an “I” beam; the outer bands of the high modulus elastomer act like the flanges of the “I” beam. These flanges add moment of inertia for high bending stiffness, and are very high in shear modulus as well. This forces the shear strain to occur across the thickness tshear. This shear strain is the value used to calculate the transverse beam deflection due to shear.

For homogeneous, isotropic materials, the shear modulus and tensile modulus are related by Poisson's ratio, as given in Equation (10):

For elastomeric materials like cast polyurethane, Poisson's ratio is generally close to 0.45. Therefore, given Young's tensile modulus, shear modulus can be calculated, and vice versa.

The “G” and the “A” for Equation 6 are now defined. The product of the beam moment of inertia “I” and Young's modulus “E” can be estimated as follows, using variables shown inFIG. 11:

Equations (7) and (10) explicitly calculate G and EI for the laminate elastomer beam ofFIG. 11. However, using engineering principles of area moment of inertia and the rule of mixtures in series, any laminate beam can be calculated in a similar manner. For instance, in some cases, for any number of different elastomers of the annular beam: EI may be determined as ΣEiIiwhich is a sum of products of the modulus of elasticity Eiand the moment of inertia Iiof each of the layers of the annular beam; and G may be determined as 1/Σ(vfi/Gi) where vfiis the volume fraction and Giis the shear modulus of each of the layers of the annular beam.

With EI known from Equation (10) and GA known from Equations (7) and (8), the only unknown in Equation (6) is the length LCof the contact patch125. This is a design parameter which relates to a rated load of the non-pneumatic tire being designed. The length LCof the contact patch125times a width of the contact patch125times a contact pressure P along the contact patch125will approximately equal the design load of the tire.

When the straight beam parameters E, I, G, and A are known and related to the design parameters of the laminate structure of the straight beam ofFIG. 11, the simply supported beam with boundary conditions shown inFIG. 12can be evaluated using Equations (4) and (5). An example of the results of such calculations is shown inFIG. 13. Using the laminate configuration ofFIG. 11, with geometric values of t1, t2, t3, and t4that are commensurate with a total tire thickness in the radial (z) direction of 100 mm,FIG. 13shows that the ratio zs/zbincreases as the difference between E1and E2increases.

Additional work by the inventor has shown that a homogeneous contact pressure distribution can be obtained along the length LCof the contact patch125of the non-pneumatic tire110provided zs/zbis sufficiently high. For example, in some embodiments, when zs/zbis at least about 1.2, in some cases at least about 1.5, in some cases at least 2, in some cases at least 3, and in some cases even more (e.g., 4 or more), the contact pressure will be substantially uniform.

FIG. 14shows an example of a finite-element model of an embodiment of the annular beam130comprising the shear band131loaded between two parallel surfaces and producing the contact patch125having the length LC.

FIG. 15shows the contact pressure through the length LCof the contact patch125for the laminate configuration or for an isotropic configuration of the shear band131of the annular beam130ofFIG. 14. With an isotropic elastomer cross section of E=80 MPa, the contact pressure is very non-uniform. The contact pressure peaks occur at the entrance and exit of the contact patch125, and the contact pressure is at a minimum in the center of the contact patch125. With a laminate configuration like that ofFIG. 11, with E1=205 MPa and E2=16 MPa, the pressure distribution is substantially uniform.

The annular beam130comprising the shear band131ofFIG. 14can be connected to the hub120via support members1421-142T(i.e., spokes) to create the non-pneumatic tire110. An example of a corresponding finite-element model of an embodiment of the non-pneumatic tire110comprising the annular beam130including the shear band131ofFIG. 14, the spokes1421-142Tand the hub120is shown inFIG. 16. In this example, the non-pneumatic tire110has dimensions 20.5×25—a size used in the construction industry, with the outer diameter DTOof around 1.5 meters. The contact patch125has the length LC=370 nm when loaded to a design load of 11 metric tons.FIG. 17provides the principle strains in the annular beam130comprising the shear band131ofFIG. 16. Maximum elastomer strains are about 0.09 (9%) which is well within the allowable cyclic strain capabilities of thermoset polyurethanes.

FIG. 17further shows the contact pressure profile through the length LCof the contact patch125of the non-pneumatic tire ofFIG. 16for various laminate configurations and for an isotropic configuration of the shear band131of the annular beam130. As with the beam analysis ofFIGS. 14 and 15, the results show that the isotropic case gives pressure peaks at the entrance and exit of the contact patch125. In this case, pressure peaks of almost 1 MPa (=10 bar=150 psi) occur. When laminate configurations are used, the pressure profile becomes more uniform. As the difference between E1and E2increases, the pressure becomes progressively more uniform.

In some embodiments, certain elastomeric materials may exhibit favorable non-linear stress vs. strain characteristics. For example, in some embodiments, a choice may be made of a material having a very non-linear material behavior, for which the secant modulus decreases with increasing strain. The “modulus” is the initial slope of the stress vs. strain curve, often termed “Young's modulus” or “tensile modulus.” In some embodiments, materials can be used that have a high Young's modulus that is much greater than their secant modulus at 100% strain, which is often termed “the 100% modulus.” The “secant modulus” is the tensile stress divided by the tensile strain for any given point on the tensile stress vs. tensile strain curve measured per ISO 527-1/-2. This nonlinear behavior provides efficient load carrying during normal operation, yet enables impact loading and large local deflections without generating high stresses.

Some thermoset and thermoplastic polyurethanes have this material behavior. An example of such a favorable material is shown inFIG. 18. The measured stress vs. strain curve of COIM's PET-95A, with curative MCDEA, has a Young's modulus of 205 MPa. However, the secant modulus at 100% strain is only 19 MPa. This may be a favorable attribute in some embodiments; when following the design principles earlier disclosed, the tire normally operates in the 5 to 9% strain region. In this region, the material is moderately stiff and the slope of the stress vs. strain curve is fairly constant. However, if local deformation occurs due to road hazards or impacts, the material is capable of large strains, without generation of high stresses. This minimizes vehicle shock loading, and enhances tire durability.

Elastomers are often used in areas of high imposed strains. As such, in some application, testing protocol typically focuses on the performance at high strains, such as 100%, 200%, or more. Mechanical designs that carry load in tension and bending typically do not use one homogeneous elastomer—they employ reinforcements as well. Some embodiments of the annular beam130opens this new design space by leveraging this material non-linearity with a favorable mechanical design.

The wheel100i, including its annular beam130, may be implemented in various other ways in other embodiments.

For example, in some embodiments, the annular beam130may be designed based on principles discussed in U.S. Patent Application Publication 2014/0367007, which is hereby incorporated by reference herein, in order to achieve the homogeneous contact pressure along the length LCof the contact patch125of the wheel100iwith the ground. The use of multiple elastomers can be combined with a more complex geometry such that the resulting performance is superior to that which could be obtained by using either technology by itself.

In this embodiment, and with reference toFIGS. 19 and 20, the shear band130comprises an outer rim133, an inner rim135, and a plurality of openings1561-156Nbetween the outer rim133and the inner rim133in addition to including the layers1321-132Nof the different elastomeric materials M1-ME. The shear band131comprises a plurality of interconnecting members1371-137Pthat extend between the outer rim133and the inner rim135and are disposed between respective ones of the openings1561-156N. The interconnecting members1371-137Pmay be referred to as “webs” such that the shear band131may be viewed as being “web-like” or “webbing”. In this embodiment, the shear band131comprises intermediate rims151,153between the outer rim133and the inner rim135such that the openings1561-156Nand the interconnecting members1371-137Pare arranged into three circumferential rows between adjacent ones of the rims133,151,153,135. The shear band131, including the openings1561-156Nand the interconnecting members1371-137P, may be arranged in any other suitable way in other embodiments.

The openings1561-156Nof the shear band131help the shear band131to deflect predominantly by shearing at the contact patch125under the loading on the wheel100i. In this embodiment, the openings1561-156Nextend from the inboard lateral side147to the outboard lateral side149of the non-pneumatic tire110. That is, the openings1561-156Nextend laterally though the shear band131in the axial direction of the wheel100i. The openings1561-156Nmay extend laterally without reaching the inboard lateral side147and/or the outboard lateral side149of the non-pneumatic tire110in other embodiments. The openings1561-156Nmay have any suitable shape. In this example, a cross-section of each of the openings1561-156Nis circular. The cross-section of each of the openings1561-156Nmay be shaped differently in other examples (e.g., polygonal, partly curved and partly straight, etc.). In some cases, different ones of the openings1561-156Nmay have different shapes. In some cases, the cross-section of each of the openings1561-156Nmay vary in the axial direction of the wheel100i. For instance, in some embodiments, the openings1561-156Nmay be tapered in the axial direction of the wheel100isuch that their cross-section decreases inwardly axially (e.g., to help minimize debris accumulation within the openings1561-156N).

Therefore, in this embodiment, the shear band131of the annular beam130comprises both (1) the openings1561-156Nand (2) the layers1321-132Nof the different elastomeric materials M1-ME. By using both geometry and material effects, further optimization is possible. For example, while thermoset polyurethanes and thermoplastic polyurethanes have a wide processing and optimization window (e.g., modulus values between 10 MPa and 300 MPa being readily assessable), in some embodiments, the physics may demand a very large bending stiffness and a very low shear stiffness, if a long contact patch of low, homogenous pressure is desired, and combining the openings1561-156Nand the layers1321-132Nof the different elastomeric materials M1-MEmay allow to achieve desired effects.

FIG. 20shows a finite-element model of an embodiment of the non-pneumatic tire110having these combined technologies. In this non-limiting example, a webbing geometry and laminate configuration have been designed to give about a 0.1 MPa contact pressure, through a length of 600 mm. The length LCof the contact patch125of the embodiment ofFIG. 20represents a large percentage of the radius of the tire, which is 750 mm.

The contact pressure profile through the length LCof the contact patch125of the non-pneumatic tire ofFIG. 20is shown inFIG. 21. In this non-limiting example, the inventor has used a deformable ground, corresponding to the stiffness of clay. This more fully represents the actual usage of such a tire in an off-road condition. The pressure distribution is fairly uniform, equal to about 0.105+/−0.05 MPa (=1.05 bar=16 psi). This level of contact pressure may be particularly appropriate in an agricultural tire usage.

In some embodiments, the wheel100i, including its non-pneumatic tire110, may enable a design space that may not be readily possible with pneumatic tires. Notably, in some embodiments, the wheel100imay be designed to be relatively narrow yet have a high load carrying capacity and a long contact patch.

For example, in some embodiments, the wheel100imay be such that (1) a ratio WT/DTOof the width WTof the non-pneumatic tire110over the outer diameter DTOof the non-pneumatic tire110is no more than 0.1 and (2) a ratio DH/DTOof the diameter of the hub120over the outer diameter DTOof the non-pneumatic tire110is no more than 0.5, namely:WT/DTO≤0.15 (15%)DH/DTO≤0.50 (50%)

For instance, in some embodiments, the ratio WT/DTOof the width WTof the non-pneumatic tire110over the outer diameter DTOof the non-pneumatic tire110may be less than 0.1, in some cases no more than 0.08, in some cases no more than 0.06, and in some cases no more than 0.04, and/or the ratio DH/DTOof the diameter of the hub120over the outer diameter DTOof the non-pneumatic tire110may be less than 0.5, in some cases no more than 0.4, and in some cases no more than 0.3.

As another example, in some embodiments, the wheel100imay be such that a ratio Lc/RTOof the length Lcof the contact patch125of the non-pneumatic tire110at the design load over an outer radius RTOof the non-pneumatic tire110(i.e., half of the outer diameter DTOof the non-pneumatic tire110) is at least 0.4, in some cases at least 0.5, in some cases at least 0.6, in some cases at least 0.7, in some cases at least 0.8, in some cases at least 0.9, and in some cases even more (e.g., 1 or more).

FIG. 22shows an example of a finite-element model of the non-pneumatic tire110ofFIG. 20, having the width WT=120 mm, and the outer diameter DTO=1500 mm. For inflated tires, a small width and a large outer diameter result in the need for a relatively large mounting rim. The equilibrium curve mechanics of both radial and bias tires are such that a width of 120 mm would result in a maximum sidewall height of only about 120 mm. This limits the contact patch length as well as the ability of the tire to absorb energy when traversing uneven terrain.

In this example, the length LCof the contact patch125may approach or be larger than the outer radius of the non-pneumatic tire110and there is a larger distance between the tire outer diameter DTOand the hub120. As a result, in this example, the load carrying capacity of the non-pneumatic tire110can be quite large. With WT=120 mm and DTO=1500 mm, the design load can be about 750 kg, with sustained speeds of 30 kph or more permitted, with a ground contact pressure at the contact patch125of about 1 bar.

The non-pneumatic tire110may comprise other components in other embodiments. For example, in some embodiments, as shown inFIG. 23, the tread150may comprise a reinforcing layer170disposed within its elastomeric material160(e.g., rubber) and extending in the circumferential direction of the wheel100i.

For example, in some embodiments, the reinforcing layer170may comprise a layer of reinforcing cables that are adjacent to one another and extend generally in the circumferential direction of the wheel100i. For instance, in some cases, each of the reinforcing cables may be a cord including a plurality of strands (e.g., textile fibers or metallic wires). In other cases, each of the reinforcing cables may be another type of cable and may be made of any material suitably flexible along the cable's longitudinal axis (e.g., fibers or wires of metal, plastic or composite material).

As another example, in some embodiments, the reinforcing layer170may comprise a layer of reinforcing fabric. The reinforcing fabric comprises thin pliable material made usually by weaving, felting, knitting, interlacing, or otherwise crossing natural or synthetic elongated fabric elements, such as fibers, filaments, strands and/or others, such that some elongated fabric elements extend transversally to the circumferential direction of the wheel100ito have a reinforcing effect in that direction. For instance, in some cases, the reinforcing fabric may comprise a ply of reinforcing woven fibers (e.g., nylon fibers or other synthetic fibers).

In some cases, the reinforcing layer170of the tread150may be substantially inextensible in the circumferential direction of the wheel100i. The non-pneumatic tire110may thus be such that its annular beam130is free of any substantially inextensible reinforcing layer running in its circumferential direction while its tread150includes the reinforcing layer170that may be substantially inextensible in its circumferential direction.

The tread150including the reinforcing layer170may be provided in any suitable way. For example, in some embodiments, the tread150may be manufactured separately from the annular beam130and then affixed to the annular beam130. For instance, in some embodiments, the tread150may be manufactured by arranging one or more layers of its elastomeric material160(e.g., rubber) and its reinforcing layer170into a mold and molding them (e.g., compression molding them) into an annular configuration of the tread150. The tread150may then be affixed to the annular beam130in any suitable way. For instance, in some embodiments, the tread150may be expanded to fit about the annular beam130and then contracted to become attached to the annular beam130. In some examples, this may be achieved by a coefficient of thermal expansion of the reinforcing layer170of the tread150allowing the reinforcing layer170to expand for stretching the elastomeric material160of the tread150in order to fit the tread150around the annular beam130and then to contract for attaching the tread150to the annular beam130. The tread150may be affixed to the annular beam130in any other suitable manner in other examples (e.g., including by using an adhesive to adhesively bond the tread150and the annular beam130).

While in embodiments considered above the wheel100iis part of the construction vehicle10, a wheel constructed according to principles discussed herein may be used as part of other vehicles or other machines in other embodiments.

For example, with additional reference toFIGS. 24 and 25, in some embodiments, an all-terrain vehicle (ATV)210may comprise wheels2201-2204constructed according to principles discussed herein in respect of the wheel100i. The ATV210is a small open vehicle designed to travel off-road on a variety of terrains, including roadless rugged terrain, for recreational, utility and/or other purposes. In this example, the ATV210comprises a frame212, a powertrain214, a steering system216, a suspension218, the wheels2201-2204, a seat222, and a user interface224, which enable a user of the ATV210to ride the ATV210on the ground.

The steering system216is configured to enable the user to steer the ATV210on the ground. To that end, the steering system216comprises a steering device228that is operable by the user to direct the ATV210along a desired course on the ground. In this embodiment, the steering device228comprises handlebars. The steering device228may comprise a steering wheel or any other steering component that can be operated by the user to steer the ATV210in other embodiments. The steering system216responds to the user interacting with the steering device228by turning respective ones of the wheels2201-2204to change their orientation relative to the frame212of the ATV210in order to cause the ATV210to move in a desired direction. In this example, front ones of the wheels2201-2204are turnable in response to input of the user at the steering device228to change their orientation relative to the frame212of the ATV210in order to steer the ATV210on the ground. More particularly, in this example, each of the front ones of the wheels2201-2204is pivotable about a steering axis230of the ATV210in response to input of the user at the steering device228in order to steer the ATV210on the ground. Rear ones of the wheels2201-2204are not turned relative to the frame212of the ATV210by the steering system216.

The suspension218is connected between the frame212and the wheels2201-2204to allow relative motion between the frame122and the wheels2201-2204as the ATV210travels on the ground. For example, the suspension218enhances handling of the ATV210on the ground by absorbing shocks and helping to maintain traction between the wheels201-204and the ground. The suspension218may comprise an arrangement of springs and dampers. A spring may be a coil spring, a leaf spring, a gas spring (e.g., an air spring), or any other elastic object used to store mechanical energy. A damper (also sometimes referred to as a “shock absorber”) may be a fluidic damper (e.g., a pneumatic damper, a hydraulic damper, etc.), a magnetic damper, or any other object which absorbs or dissipates kinetic energy to decrease oscillations. In some cases, a single device may itself constitute both a spring and a damper (e.g., a hydropneumatic, hydrolastic, or hydragas suspension device).

In this embodiment, the seat222is a straddle seat and the ATV210is usable by a single person such that the seat222accommodates only that person driving the ATV210. In other embodiments, the seat222may be another type of seat, and/or the ATV210may be usable by two individuals, namely one person driving the ATV210and a passenger, such that the seat222may accommodate both of these individuals (e.g., behind one another or side-by-side) or the ATV210may comprise an additional seat for the passenger. For example, in other embodiments, the ATV210may be a side-by-side ATV, sometimes referred to as a “utility terrain vehicle” or “utility task vehicle” (UTV).

The wheels2201-2204engage the ground to provide traction to the ATV210. More particularly, in this example, the front ones of the wheels2201-2204provide front traction to the ATV10while the rear ones of the wheels2201-2204provide rear traction to the ATV10.

Each wheel220iof the ATV210may be constructed according to principles described herein in respect of the wheel100i, notably by comprising a non-pneumatic tire234and a hub232that may be constructed according to principles described herein in respect of the non-pneumatic tire110and the hub120. The non-pneumatic tire234comprises an annular beam236and an annular support241that may be constructed according principles described herein in respect of the annular beam130and the annular support140. For instance, the annular beam236comprises a shear band239comprising a plurality of layers2321-232Nof different elastomeric materials M1-MEand the annular support241comprises spokes2421-242Jthat may be constructed according to principles described herein in respect of the shear band131and the spokes1421-142T. As another example, in some embodiments, with additional reference toFIG. 26, a motorcycle410may comprise a front wheel4201and a rear wheel4202constructed according to principles discussed herein in respect of the wheel100i.

As another example, in some embodiments, a wheel constructed according to principles discussed herein in respect of the wheel100imay be used as part of an agricultural vehicle (e.g., a tractor, a harvester, etc.), a material-handling vehicle, a forestry vehicle, or a military vehicle.

As another example, in some embodiments, a wheel constructed according to principles discussed herein in respect of the wheel100imay be used as part of a road vehicle such as an automobile or a truck.

As another example, in some embodiments, a wheel constructed according to principles discussed herein in respect of the wheel100imay be used as part of a lawnmower (e.g., a riding lawnmower or a walk-behind lawnmower).

Although embodiments considered above pertain to a non-pneumatic tire, in other embodiments, other annular devices, such as, for instance, tracks for vehicles and/or conveyor belts, may comprise an annular beam constructed according to principles discussed herein in respect of the annular beam130.

Certain additional elements that may be needed for operation of some embodiments have not been described or illustrated as they are assumed to be within the purview of those of ordinary skill in the art. Moreover, certain embodiments may be free of, may lack and/or may function without any element that is not specifically disclosed herein.

Any feature of any embodiment discussed herein may be combined with any feature of any other embodiment discussed herein in some examples of implementation.

In case of any discrepancy, inconsistency, or other difference between terms used herein and terms used in any document incorporated by reference herein, meanings of the terms used herein are to prevail and be used.

Although various embodiments and examples have been presented, this was for the purpose of describing, but not limiting, the invention. Various modifications and enhancements will become apparent to those of ordinary skill in the art and are within the scope of the invention, which is defined by the appended claims.