Non-pneumatic tire for track system

Abstract

A non-pneumatic inner roller for use in a ring track system, the track system including a non-pneumatic inner roller and a track having an inner periphery, the non-pneumatic tire having a tapered profile, the larger diameter of the tapered profile being positioned laterally outward toward the track, and the smaller diameter of the tapered profile being positioned inward toward the track.

Description

Technical Field

[0001] This disclosure relates to non-pneumatic tires for tracked systems, and more generally to vehicles such as agricultural or industrial vehicles. Background Technology

[0002] Tracked systems are used in a variety of industries, particularly for off-road vehicles requiring high traction. These vehicles can include engineering vehicles (loaders, excavators, etc.), military vehicles (tanks), and agricultural vehicles (tractors, sprayers, etc.). Tracked systems enhance traction and / or buoyancy on soft, slippery, and / or irregular surfaces.

[0003] A track system may include track modules. A track module includes a frame, drive wheels rotatably mounted to the frame, guide idlers and driven idlers, and center rollers (or bogie wheels). A circular (often referred to as "annular" or "continuous") flexible track extends around the wheel.

[0004] Track systems support tracked vehicles. Vehicle loads are transferred from the vehicle to the track module, from the frame to the wheels, to the track, and then from the track to the ground. A track module may include multiple intermediate rollers, with most or all of the vehicle load supported by these rollers when they contact the inner periphery of the track. Therefore, the track is compressed by the intermediate rollers.

[0005] Tracked vehicles can be very large. Therefore, each intermediate roller can exert a high level of compressive stress on the track. These compressive stresses can be exacerbated by packing constraints (the expectation of small intermediate rollers) and wheel fatigue constraints (leading to the use of metal wheels). Metal wheels do not flex, meaning all flexing occurs within the track. The combination of small, rigid rollers and high loads creates high localized compressive stresses on the track.

[0006] Elastomer tracks can be expensive. Tracks can weigh hundreds of kilograms and include multiple reinforcing layers within a rubber matrix. When a tracked vehicle moves, each roller exerts cyclic stress on the track, causing large changes in the strain energy within the track. This, in turn, becomes a driving factor for crack propagation. Therefore, tracks may fail prematurely and become unusable.

[0007] Improving track durability can be challenging. Compressive stress from the center rollers is difficult to reduce because it is directly related to the load, which can be applied according to customer requirements. Increasing the size and / or number of center rollers can be difficult due to packaging constraints. Track durability can be improved by adding more reinforcing layers or improving the fatigue properties of the rubber matrix, but this may increase track costs. Therefore, innovation in track system design is required. Summary of the Invention

[0008] According to one aspect of the invention A non-pneumatic tire is provided for use as a center roller in a track system. The non-pneumatic tire has an outer radial extent with a tapered profile, the tapered profile having a maximum circumference offset outward from the tire centerline. When the tire is loaded with a design load on the inner periphery of the track, the contact width is at least 75% of the tire crown width; in other cases, at least 80%; in other cases, at least 85%; and in other cases, 90%. The ratio of the maximum circumference outward to the minimum circumference inward is at least 1.01; in other cases, at least 1.02; in other cases, at least 1.03; and in other cases, even greater.

[0009] According to one aspect of the invention A track system is provided, comprising a non-pneumatic tire serving as a center roller, the non-pneumatic tire having an outer radial extent with a tapered profile having a maximum circumference offset from the tire's centerline toward an outer axial extent. The track system also includes an annular track comprising a plurality of reinforcing plies. The axial extent of any one of these plies is 20 mm or greater from the axial extent of the track.

[0010] According to one aspect of the invention A non-pneumatic tire is provided for use as a center roller in a track system. The non-pneumatic tire includes a rim and an elastomer portion that partially encapsulates the rim. The elastomer portion also includes a plurality of holes arranged radially outward from the rim and extending in an axial direction. Attached Figure Description

[0011] The following detailed description of the implementation scheme is provided by way of example only, with reference to the accompanying drawings, in which:

[0012] Figure 1 This is a side view of a track system including the NPT as the central roller.

[0013] Figure 2 It is a perspective view of a track system including NPT as the central roller.

[0014] Figure 3 An exemplary NPT used as a middle roller is shown.

[0015] Figure 4 This is a side view of an exemplary NPT.

[0016] Figure 5 The lateral crown profile of an exemplary NPT is shown.

[0017] Figure 6 The crown width of the NPT is defined.

[0018] Figure 7 The transverse profile of an NPT according to one aspect of the present invention is shown.

[0019] Figure 8 The hole profile of an exemplary NPT is shown.

[0020] Figure 9 Alternative holes for NPT according to various aspects of the present invention are shown.

[0021] Figure 10 Another alternative aperture embodiment of the NPT according to various aspects of the present invention is shown.

[0022] Figure 11 An example NPT rim is shown.

[0023] Figure 12 It shows Figure 11 The rim is encapsulated in NPT.

[0024] Figure 13 A close-up of the lateral extent of the NPT and rim is shown.

[0025] Figure 14 An alternative rim design that is not encapsulated is shown.

[0026] Figure 15 It is based on the existing technology of the roller.

[0027] Figure 16 It is based on the lateral profile of the roller in the prior art.

[0028] Figure 17 This is a schematic diagram of the track design.

[0029] Figure 18 A schematic end view of the track reinforcement layer is shown.

[0030] Figure 19 A schematic front view of the track reinforcement layer is shown.

[0031] Figure 20 The FEA results are provided when the track is subjected to uniform pressure.

[0032] Figure 21 The FEA results are shown when the track is loaded by the NPT of the roller according to the present invention.

[0033] Figure 22 The FEA results are shown when the track is loaded by rollers in the prior art.

[0034] Figure 23 The FEA of the contact imprint of the rollers on the track in the NPT is shown.

[0035] Figure 24 The FEA of the contact imprint of a roller on a track in the prior art is shown.

[0036] Figure 25 The contact imprint area measured by rollers in NPT and the prior art is shown.

[0037] Figure 26 The image shows damage to the internal tracks after testing with rollers in the prior art.

[0038] Figure 27 The internal track damage is shown after testing with rollers in the NPT.

[0039] Figure 28 A tension-based NPT used as a middle roller according to an aspect of the invention is shown.

[0040] Figure 29 It is a wheel rim containing NPT thermoplastic resin. Terminology Definition

[0041] Unless otherwise stated, the following terms are defined in this disclosure, wherein material properties refer to properties at ambient temperature:

[0042] The axis of rotation of a tire or wheel is the line around which the tire or wheel rotates. The axis of rotation is parallel to the "Y" coordinate system shown in the attached diagram. "Radial," or the letter "R," refers to the direction outward from the axis of rotation, perpendicular to the axis of rotation and parallel to the coordinate axis "Y." The "Y" coordinate direction is also referred to as the "axial" direction and the "lateral" direction. Figure 3 The curve shown indicates that the "circumference" direction is perpendicular to the plane formed by the radial axis "R" and the rotation axis "Y," and it typically extends longitudinally around the tire, such as... Figure 3 As shown

[0043] "Wheel hub" refers to any structure used to support the tires and can be attached to the axle of a vehicle.

[0044] The vertical direction is Figure 2 As shown, and as used herein, the axis is perpendicular to the lateral direction "Y". Figure 2 The "longitudinal" direction, shown as the "X" axis, is perpendicular to both the lateral and vertical directions. These coordinates are shown as follows: Figure 2 The component coordinates are defined in the diagram. The positive "X" direction is the usual direction of vehicle travel, while the positive "Z" direction is usually considered "up".

[0045] The "lateral profile" of the crown profile of the intermediate roller is the profile of the outer radial range of the intermediate roller in the RY plane.

[0046] When referring to elastomers, "modulus" means the Young's tensile modulus as measured according to ASTM D638. This tensile modulus can be calculated as the secant modulus at 0.5% tensile strain.

[0047] When referring to elastomers, unless otherwise specified, “dynamic shear modulus” (G*) means the modulus measured in Dynamic Measurement Analysis (DMA) at 1% shear strain, 10 Hz, and a standard temperature of 23°C.

[0048] When referring to reinforced thermoplastic elastomers, "modulus" refers to Young's tensile modulus as measured according to ASTM D638. This tensile modulus can be calculated as the secant modulus at 0.2% tensile strain.

[0049] The tire's "design load" is the operating load of the tire when the track system is loaded to its maximum load.

[0050] The relationship between tire vertical force, deflection, and area occupied can be measured according to SAE J2704.

[0051] "Middle roller" refers to, for example Figure 1 The position of the wheels in the tracked system shown.

[0052] "Idle wheel" refers to, for example Figure 1 The position of the wheels in the tracked system shown. Detailed Implementation

[0053] Figure 1 A track system 100 is shown, comprising a chassis frame 130, an annular track 110, a plurality of center rollers 200, and a plurality of idler rollers 300. The track system 100 may be designed such that most or all of the track system load is supported by the center rollers 200. The track may include drive lugs 120 extending inwardly from the inner surface of the track near the track centerline. The track 110 may also include treads and tread blocks extending outwardly from the track 110.

[0054] Figure 2 A perspective view of the track system 100 is shown. Each center roller 200 has an outer side 210 oriented laterally toward the track 110. Each center roller has an inner side 220 oriented toward the track centerline. Generally, the inner side of the center roller may be adjacent to a drive lug of the track 110.

[0055] Figure 3An exemplary intermediate roller 200 according to one aspect of the invention is shown. The intermediate roller is a non-pneumatic tire (NPT). The NPT includes an elastomer body 230 and a rim 250. The elastomer body may include a plurality of holes 240 extending in an axial direction (shown herein as "Y"). The holes may extend from one lateral extent to another. The rim may be partially enclosed by the elastomer body. The outer radial extent of the elastomer body defines a lateral profile 250 in the RY plane. The lateral profile contacts the inner periphery of the track.

[0056] Figure 4 A side view of the NPT is shown. In this exemplary example, the elastomer body bore 240 extends across the lateral extent of the elastomer. A vehicle mounting hole 270 is provided in the rim 250 for mounting to a vehicle.

[0057] Figure 5 The lateral profile 260 of the NPT 200 is shown. This profile has a width W. 胎冠 This width is considered to be the width that the NPT might contact the track when it is loaded to the design load. Furthermore, this exemplary profile is tapered; in other words, the NPT is shown here with a tapered lateral profile. This profile is asymmetrical, with its maximum circumference offset by d from the centerline towards the outside of the NPT. OUT For this exemplary contour, the width of the contact area may be equal to W. 胎冠 The centerline 280 (shown here as a dashed line along the outer surface of the tire) is positioned in the centerline plane, which is perpendicular to the tire's axis of rotation. The maximum circumference is measured about the tire's axis of rotation. The maximum circumference also has a maximum radius from the centerline, shown here as Rout. The minimum circumference has a minimum radius, shown here as Rin.

[0058] In some cases, NPTs can be designed to have a lateral profile that is curved near the axial range, such as... Figure 6 As shown. In this case, W 胎冠 It is defined as the lateral distance from a point on the profile tangent to a line inclined at 30 degrees from the axial direction to a similar point on the opposite lateral extent. The maximum and minimum perimeters are in W... 胎冠 Measurements were taken at various points within the area.

[0059] The inventors conducted extensive numerical and experimental tests on the compliance NPT of the intermediate roller used in the tracked system. These tests and results will be disclosed in subsequent chapters.

[0060] Based on their work, the inventors have determined that, according to one aspect of the invention, the outer radial range of the NPT used in a track system may have a tapered profile, the tapered profile having a maximum circumference offset from the tire centerline 280 toward the outer range. When the tire is loaded with a design load on the inner periphery of the track, the contact width is at least 75% of the tire crown width; in other cases, at least 80%; in other cases, at least 90%; and in other cases, 100%. The ratio of the maximum circumference toward the outer range to the minimum circumference toward the inner range is at least 1.01; in other cases, at least 1.02; in other cases, at least 1.03; and in other cases, even greater.

[0061] Specifically, in Figure 5 In the case of an exemplary NPT, W 胎冠 =132mm. The contact imprint width under design load is equal to 132mm, with a ratio of 100%.

[0062] For this NPT, d OUT =35mm. Additionally, R OUT =173.5mm and R IN =168.5mm. R OUT / R IN The ratio is 1.03.

[0063] In some cases, the maximum circumference may coincide with the outer lateral extent 210 of the crown profile 260, such as... Figure 7 As shown.

[0064] The inventors have developed a method for measuring the contact imprint width of the center roller in a track system. This method is easy to use and will enable those skilled in the art to determine the contact width of the center roller when it is loaded to the design load, relative to the tire crown width W. 胎冠 The ratio: 1. Load the tracked system to the design load. 2. On the inner periphery of the track in the track system, at a longitudinal (X) position immediately adjacent to the center roller of the track system, apply a 25mm to 35mm strip of Rust-oleum red multipurpose paint laterally. The lateral extent of the paint strip should be wider than that of the center roller. 3. Within 30 seconds, move the track system in the X direction at a low speed of less than 0.5 kph until the middle roller completely crosses the painted strip. 4. Stop the track system. 5. Remove the middle roller. 6. Measure the width of the red paint on the tire crown of the roller. This width is the contact mark width.

[0065] Figure 8An exemplary hole profile 245 is shown. For ease of disclosure, Figure 8 We use a Cartesian coordinate system XY, defined such that the origin lies on the rotation axis of the NPT. The Y-axis coincides with the radial axis, and the X-axis is parallel to the radial axis. Figure 3 The X-axis is defined in [the document / reference].

[0066] The profile may include a radially outward segment between points P1 and P2 that follows a radial equilibrium curve, such that: y=y1-c1x 2

[0067] In this exemplary example, y1 = 156 mm and c1 = 0.22. These values ​​depend on the size of the hole and its radial position. Furthermore, in this case, the hole is symmetrical about the y-axis.

[0068] By using a radial equilibrium curve as the hole path within the outer radial range of the hole, the elastomer body can bear loads in a compressive manner. The efficiency of the elastomer in bearing loads in a compressive manner is much higher than that in bearing loads in a shear manner.

[0069] Through numerical modeling and practical verification, the inventors have discovered that in the total hole height H 总 A significant percentage of holes that follow the radial balance curve resist cracking during operation. Specifically, when H EQ With H 总 Performance is optimized when the ratio is at least 0.15; 0.20 in other cases; and at least 0.30 in other cases. Figure 8 Exemplary hole (which is with) Figure 3 The exemplary NPT includes the same holes (with H) 总 =24mm and H EQ =6.0mm, ratio is 0.25.

[0070] Figure 9 and Figure 10 Alternative hole profiles 246 and 247 are shown. The scope of the invention is intended to include any suitable hole profile (typically square, polygonal, or circular), and may also include multiple rows of holes.

[0071] The elastomer body can be supported by the wheel rim. Figure 11An exemplary rim design is illustrated. The rim 400 has: a radially inward flange 410 extending in a plane Rq, which is perpendicular to the tire's axis of rotation; and a radially outward flange 420 extending in a direction q, which is parallel to the tire's axis of rotation. The radially outward flange 420 may be partially or completely enclosed by an elastomer body. The outward flange may include holes 430 that facilitate complete encapsulation during forming operations. These holes extend in the radial direction. The radially inward flange has a plurality of mounting holes 470 for mounting to a vehicle.

[0072] Figure 12 A cross-sectional view of the NPT is shown, so that the rim 400 intersecting with the elastomer body 230 can be clearly seen.

[0073] Figure 13 The axial extent of the rim is shown. Due to being fully encapsulated, the axial extent of the elastomer body extends further than the axial extent of the rim. The elastomer body extends at a distance D... 本体_轮辋 The track is not supported by the rim. The inventors have found that this design feature is useful in reducing track stress because it creates compliance near the lateral range of the NPT. Through numerical modeling and practical verification, the inventors have found that D 本体_轮辋 It should be at least 15mm; in other cases, at least 20mm; and in other cases, even more. Figure 3 The exemplary NPT has a D-body rim of 23mm.

[0074] In some instances, such as Figure 14 As shown, having an unencapsulated rim 401 may be advantageous.

[0075] Figure 15 and Figure 16 The image shows a roller in the prior art. The tread profile, while asymmetrical, is not tapered. The rim is not encapsulated. There are no holes. The design includes a high-modulus polyurethane tread molded onto a steel rim. Therefore, this roller is very rigid.

[0076] Figure 17 A schematic diagram of a track design according to one aspect of the invention and the orientation of the tapered NPT 101 is shown. The NPT circumference is smallest on the inner side 220 of the drive lug 607 facing the track 606 and largest on the outer side 210. In this exemplary track design, there are five layers, each layer comprising a steel cable. Figure 18 and Figure 19 A schematic diagram of the layered structure is provided. Each layer has 700 layers through... Figure 18 The cross-section of the cable 710 shown is... Figure 19 The deviation angle relative to the track circumference and the distance from the axial direction are shown in the diagram. Figure 17, Figure 18 and Figure 19 The naming provided in the example track layer structure has:

[0077] Table 1

[0078]

[0079] Historically, tire design has assumed a flat (horizontal) contact surface. Superficially, this seems like a reasonable assumption for non-pneumatic tires used as inner sprockets. The inner perimeter of a track is horizontal, i.e., the surface is parallel to the ground. Tracks are deformable, but a priori, there is no reason to assume they are not horizontal.

[0080] However, the inventors decided to test this hypothesis. They constructed a FEA model of the track and applied appropriate boundary conditions related to track tension and ground contact. Then, the inventors applied a uniform pressure of 1.3 bar to the area accessible to the rollers in near-compliant track. The total area was defined such that pressure × area = 15,000 N, which is the design load for a roller in NPT.

[0081] The results are shown in Figure 20 Surprisingly, the area subjected to uniform pressure deformed, exhibiting a distinctly asymmetrical profile. The vertical deflection near the drive lug was approximately 4 mm, while the deflection near the outer edge of the track was approximately 8 mm. The inventors hypothesize that a tapered, compliant tire is needed to generate uniform pressure on the track surface. Ideally, uniform pressure would minimize maximum track pressure, which in turn reduces cyclic stress and strain within the track. This, in turn, reduces heat buildup. These important performance parameters are explained in subsequent chapters.

[0082] The inventors have discovered that certain industrial and practical constraints cause tracks to undergo conical deformation when subjected to uniform pressure. For example... Figure 17 As shown, none of the reinforcing plates extend to the lateral extent of the track. Industrial tolerances for plate end placement require a considerable amount of space between the track edge and the plate end. Clearly, the track is relatively unsupported at the edges, which contributes to tapered deformation.

[0083] Therefore, the roller design in a tapered NPT can help optimize the performance of tracks that are most easily industrialized. Thus, one aspect of the invention is: an NPT comprising a tapered lateral profile serving as a central roller in a track system including reinforcing layers. The axial extent of any one of these layers is 20 mm or more from the axial extent of the track.

[0084] Specific aspects of the invention have been disclosed in previous chapters. Now, the inventors disclose the specific theories, numerical and empirical results used in the creation of the concept.

[0085] According to Equation 1, the cyclical change of shear stress generates heat: (1)

[0086] in: =Heat caused by viscoelastic loss f = Frequency of stress and strain oscillations =Loss angle =Oscillation stress amplitude = Modulus of elasticity

[0087] Furthermore, according to Equation 2, the crack propagates within the rubber elastomer: (2)

[0088] Where: k and a are material-related constants. G = strain energy release rate =Crack propagation rate per cycle

[0089] The strain energy release rate is directly related to the strain energy density, as defined in Equation 3 for the simple mode 1 request: (3)

[0090] Where: SED = strain energy density a = crack length

[0091] For rubber, existing technical literature indicates that the exponent 'a' in Equation 2 is approximately 2.0 for natural rubber and approximately 4.0 for styrene-butadiene rubber. Combined with Equation 3, it is clear that crack propagation may vary with increasing stress amplitude to the fourth or even eighth power. Therefore, even a moderate reduction in oscillating pressure due to the contact of the intermediate rollers can significantly improve track fatigue life and lower track operating temperature.

[0092] According to equation (1), reducing the amplitude of oscillation stress also reduces heat accumulation. Therefore, reducing the stress applied to the track by the middle roller can lower the operating temperature and slow down crack propagation.

[0093] The inventors used parametric FEA in the design of the roller and track system in NPT, thereby obtaining... Figure 3The design disclosed herein considers a range of material properties of the elastomer. An exemplary material is Lanxess thermosetting polyurethane B836. At 60°C, 10 Hz, and 1% shear strain, this elastomer has a dynamic shear modulus of approximately 17 MPa and a tan(d) of approximately 0.04. Through experiments, the inventors have determined that the dynamic shear modulus of the elastomer should not exceed 21 MPa; in some cases, not exceed 17 MPa; and in some cases, even lower. Furthermore, the tan(d) of the elastomer at 60°C should not exceed 0.09; in other cases, not exceed 0.07, and in other cases, even lower.

[0094] When loaded onto deformable tracks, FEA predicts that respectively at Figure 23 and Figure 24 The diagram shows the contact imprint shapes of roller contact imprint shape 800 in NPT and roller contact imprint shape 810 in the prior art. For example... Figure 23 As shown, the rollers in the NPT have a larger contact area and therefore a lower average contact pressure. The average contact pressure of the NPT is 1.47 MPa, while the average contact pressure of the rollers in the prior art is 2.14 MPa. The ratio of NPT pressure to prior art pressure is 0.69. Using Equation 2, taking a=2, and setting the crack propagation rate of the track with the rollers in the prior art to 100% (reference), for the same track with the NPT as the intermediate roller, a crack propagation rate of 22% can be expected. From a first-order theoretical perspective, this is equivalent to a 4.5-fold increase in track life.

[0095] Use according to Table 1 and Figure 17 The track definition was used to construct and test an exemplary mid-roller NPT. A proprietary track system configuration was constructed that enables mid-roller contact imprint measurements when various loads are applied to the inner perimeter of the track. Figure 25 The paper provides actual measured contact areas of rollers in the prior art and NPT for three different loads. The results are normalized using the contact area of ​​rollers in the prior art under 100% design load as a reference.

[0096] In the NPT, the contact area of ​​the rollers increased by approximately 50% under the design load and by approximately 40% under 133% of the design load. This is quite consistent with the FEA results, which predicted a 45% increase in contact area under the reference load.

[0097] Steady-state track temperature and track durability were measured using a proprietary track system. Proprietary conditions were employed, which the applicant has determined correspond to accelerated track fatigue conditions. Normalized results are provided in Table 2.

[0098] Table 2

[0099]

[0100] For the same track, the track system with NPT MR heated up by 18% under environmental testing conditions. Furthermore, internal cracks were detected in the system with prior art MR at 100% test duration, while no internal cracks were detected even after 400% test duration when using NPT MR. Figure 26 and Figure 27 Photographs of the track cross-sections after testing are provided for rollers in the prior art and rollers in NPT.

[0101] Therefore, in summary, the roller in the NPT according to the present invention has been implemented. The thermal performance of the track is significantly improved, with a temperature rise reduced by 18%. The fatigue performance of the track is improved by more than 4 times.

[0102] In US 63 / 507456, a patent application owned by the applicant and incorporated herein by reference, a high-modulus insert 850 is disclosed for use within the annular beam of an NPT used in a tracked system. The same concept can be applied to various aspects of the present invention, such as... Figure 28 As shown.

[0103] High-modulus inserts allow the elastomer body to operate at lower temperatures and / or enable the use of lower-modulus elastomers while supporting the same load. High-modulus inserts can be thermoplastic materials reinforced with glass or carbon fiber.

[0104] In addition, such as Figure 28 As shown, the NPT may include a spoke structure that generates tension. This spoke structure can be used in place of the previously disclosed aperture.

[0105] Figure 29 A thermoplastic rim 900 is shown that can be used in various aspects of the invention. Instead of... Figure 11 The metal rims shown, formed by thermoplastic injection, can be lightweight and may include complex geometries. These complex geometries can facilitate bonding with the elastomer body and can be used to reduce weight. For example, in the illustrated embodiment, the rim 900 has a plurality of protrusions 970 on the radially outward flange 920.

Claims

1. A non-pneumatic tire used as a center roller in a track system, the track system comprising the non-pneumatic tire and a track, the track having an inner periphery, the non-pneumatic tire having: A rotation axis extending from a first axial tire extent to a second axial tire extent; A centerline plane, which is perpendicular to the axis of rotation and lies between the first axial tire range and the second axial tire range; Tire centerline, which lies in the centerline plane and extends along the outer radial range of the non-pneumatic tire; A tapered profile, the tapered profile being formed by the outer radial range, the tapered profile having a maximum circumference offset from the tire centerline toward the first axial range or the second axial range; Wherein, when the tire is loaded with a design load on the inner periphery of the track, the contact width is at least 75% of the tire crown width; The ratio of the maximum perimeter of the outward-facing range to the minimum perimeter of the inward-facing range is at least 1.

01.

2. The non-pneumatic tire of claim 1, wherein the ratio of the maximum circumference toward the outermost range to the minimum circumference toward the innermost range is at least 1.

02.

3. The non-pneumatic tire of claim 1, wherein the ratio of the maximum circumference toward the outermost region to the minimum circumference toward the innermost region is at least 1.

03.

4. The non-pneumatic tire of claim 1, wherein the ratio of the maximum circumference toward the outermost range to the minimum circumference toward the innermost range is at least 1.

05.

5. The non-pneumatic tire according to any one of the preceding claims, wherein when the tire is loaded onto the design load on the inner periphery of the track, the contact width is at least 80% of the tire crown width.

6. The non-pneumatic tire according to any one of the preceding claims, wherein when the tire is loaded onto the inner periphery of the track to the design load, the contact width is at least 85% of the tire crown width.

7. The non-pneumatic tire according to any one of the preceding claims, wherein when the tire is loaded onto the inner periphery of the track to the design load, the contact width is at least 90% of the tire crown width.

8. The non-pneumatic tire according to any one of the preceding claims, wherein the maximum circumference coincides with the outer lateral extent of the tapered profile of the tire.

9. The non-pneumatic tire according to any one of the preceding claims, wherein the minimum circumference coincides with the inner lateral extent of the tapered profile of the tire.

10. A track system having a non-pneumatic tire serving as a center roller, the track system comprising the non-pneumatic tire and a track, the track having an inner periphery, the non-pneumatic tire having: A rotation axis extending from a first lateral range to a second lateral range; and The outer radial range of the non-pneumatic tire has a tapered lateral profile, the tapered lateral profile having a wider portion near the first lateral range and a narrower portion near the second lateral range.

11. The track system of claim 10, wherein the non-pneumatic tire is positioned on the track such that the narrow portion of the tapered profile is positioned near the inner periphery of the track, and the wider portion is positioned away from the inner periphery of the track.

12. The track system of claim 11, wherein when the tire is loaded onto the inner periphery of the track with the design load, the contact width is at least 80% of the tire crown width.

13. The track system of claim 11, wherein when the tire is loaded onto the inner periphery of the track with the design load, the contact width is at least 85% of the tire crown width.

14. The track system of claim 11, wherein when the tire is loaded onto the inner periphery of the track with the design load, the contact width is at least 90% of the tire crown width.

15. The track system according to any one of claims 10 to 14, wherein the maximum circumference coincides with the outer lateral extent of the tapered profile of the tire.

16. The track system according to any one of claims 10 to 15, wherein the minimum circumference coincides with the inner lateral extent of the tapered profile of the tire.

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