Non-pneumatic tire

Abstract

The present disclosure provides a tangential non-pneumatic tire (100). The tire (100) comprises an inner band (106), an outer band (108), and an array of spokes 102. The array of spokes (102) extends in a circumferential and radial direction of the tire (100) between the inner band (106) and the outer band (108). Each spoke in the array of spokes (102) comprises multiple circular rings that are placed adjacent to each other and is connected about their circumference so that centres of the multiple circular rings for a notional circle. Further, at least two of the spokes in the array of spokes (102) is placed laterally and offset to each other along the width of the tire (100).

Description

NON-PNEUMATIC TIRETECHNICAL FIELD

[0001] The present subject matter relates, in general, to vehicle tires and, particularly, but not exclusively, to non-pneumatic vehicle tires.BACKGROUND

[0002] Tires support the load of a vehicle and impact handling, drivability, and safety of the vehicle.

[0003] A tire is mounted on a wheel’s rim to transfer a load of the vehicle from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels.

[0004] Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures filled with air, which provide a flexible cushion that absorbs shock when the tire rolls over uneven surfaces. Tires provide a footprint, called a contact patch, that is designed to match the weight of the vehicle with the bearing strength of the surface that it rolls over by providing a bearing pressure that will not deform the surface excessively.

[0005] The pneumatic tires are susceptible to puncture when the tire encounters an object, such as a pothole or some shaped edge stone or metal pieces. Thus, to avoid such issues, non-pneumatic tires are preferred over pneumatic tires nowadays.

[0006] The non-pneumatic tires do not contain air to support the load. Thus, when these tires encounter potholes or sharp objects, they do not get punctured.BRIEF DESCRIPTION OF DRAWINGS

[0007] The detailed description is provided with reference to the accompanying figures. The left-most digit of a reference number identifies the figure in which the reference number first appears in the figures. The same numbers are used throughout the drawings to reference like features and components.

[0008] Fig. 1 illustrates a cross-sectional view of a tangential nonpneumatic tire showing a spoke, in accordance with an implementation of the present subject matter;

[0009] Fig. 2 illustrates a cross-sectional view of an array of spokes of the tangential non-pneumatic tire showing two sets of spokes having offset, in accordance with an implementation of the present subject matter;

[0010] Fig. 3 illustrates a perspective view of the array of spokes containing two sets of spokes depicting the offset , in accordance with an implementation of the present subject matter; and

[0011] Fig. 4 illustrates a cross-sectional view of the tangential nonpneumatic tire, in accordance with an implementation of the present subject matter.DETAILED DESCRIPTION OF DRAWINGS

[0012] Generally, a pneumatic tire used in most vehicles or other industrial applications comprises a tread, bead, sidewall, shoulder, and ply. The tread is the part of the tire that comes in contact with the road surface. The tire bead is the part of the tire that contacts the rim of the wheel. The characteristic feature of the pneumatic tire is the use of air-filled chamber between the rim and the tread that support the tread of the tire.

[0013] However, pneumatic tires suffer some disadvantages. For example, pneumatic tires are susceptible to punctures which results in flats and requiresimmediate repair or replacement. Also, maintenance requirements like regular inflation is a must for pneumatic tires. Besides, extreme temperatures can also affect the air pressure in pneumatic tires, potentially leading to overinflation or underinflation. In some extreme situations, pneumatic tires are also vulnerable to blowouts. Furthermore, the production and disposal of pneumatic tires, owing to their relatively shorter life as compared to non-pneumatic tires, can have environmental consequences as old tires may lead to waste management challenges.

[0014] Thus, there exists a need for a technique that counters the above- mentioned shortcomings of pneumatic tires.

[0015] To this end, the present subject matter provides for a tangential nonpneumatic tire (TN PT) that addresses the deficiencies of the conventional pneumatic tires, in particular, provides a durable, temperature insensitive, low maintenance, and puncture resistance tire.

[0016] In accordance with an embodiment of the present subject matter, the tangential non-pneumatic tire comprises an inner band, an outer band, and an array of spokes extending in a circumferential and radial direction of the tire between the inner band and the outer band. The inner band interfaces with a rim of a wheel on which the tire is to be mounted. The outer band is separated from the inner band and forms a tread portion of the tire. Each spoke in the array of spokes comprises multiple circular rings placed adjacent to each other and connected about their circumference so that centres of the multiple circular rings form a notional circle. Further, at least two of the spokes in the array of spoke is placed laterally and offset to each other along the width of the tire. Thus, the array of spokes is positioned along the width of the tire in the region between the rim and tread of the tire, throughout the circumference of the tire. In an example, the width of the array of spokes may correspond to the width of the tread of the tire.

[0017] In an example implementation, the array of spokes is formed by placing multiple spokes one behind the other, along the width of the tire. Each spoke is placed laterally and offset to each other. Further, examples where two or more of the spokes (and not all the spokes in the array) are placed laterally and offset to each other are also possible.

[0018] The array of spokes supports the load of the vehicle during the rotation of the wheel ensuring adequate traction forces and directional control.

[0019] In accordance with an example embodiment of the present subject matter, the material used for making the array of spokes and the arrangement or structural configuration of the array of spokes inside the tire, as will be elaborated subsequently, provides a supporting structure for bearing the load of the vehicle, thereby allowing the load-bearing properties of the present nonpneumatic tires to be similar or even better than those provided by the conventional pneumatic tires.

[0020] The tangential non-pneumatic tire, in accordance with the present subject matter provides many advantages over the conventional pneumatic tires. For example, the tangential non-pneumatic tire is durable, resistant to wear and tear, and resistant to puncture as it lacks an air-filled chamber. In another example, the tangential non-pneumatic tire requires low maintenance as there is no risk of leaks and it has relatively low sensitivity to temperature. In another example, the tangential non-pneumatic tire is more reliable as it can maintain its performance even if it is damaged. In another example, the tangential non-pneumatic tire is made from eco-friendly materials leading to a reduced environmental footprint.

[0021] The above and other features, aspects, and advantages of the subject matter will be better explained with regard to the following description and accompanying figures. It should be noted that the description and figures merely illustrate the principles of the present subject matter along withexamples described herein and should not be construed as a limitation to the present subject matter. It is thus understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and examples thereof, are intended to encompass equivalents thereof.

[0022] Fig. 1 illustrates a cross-sectional view of a tangential nonpneumatic tire 100 showing a spoke (hereinafter referred to as spoke 102), in accordance with an example implementation of the present subject matter. As will be apparent from the foregoing explanation, the spoke 102 is a part of the array of spokes (shown later). The array of spokes is positioned between an inner band 106 that interfaces with a rim (not shown in Fig 1 ) of a wheel on which the tire is to be mounted and an outer band 108 that forms a tread portion of the tire. The outer band 108 comprises one or more layers subsequently described in Fig. 4. In accordance with example embodiments of the present subject matter, the inner band 106 and the outer band 108 of the tangential non-pneumatic tire 100 may have a layered structure comprising one or more layers of same or different materials.

[0023] In an implementation of the present subject matter, the spoke 102 is formed by placing multiple circular rings or ring-like elements adjacent to each and connecting them about their circumference so that centres of the multiple circular rings form a notional circle. While not apparent from the view depicted in Fig. 1 , the circular rings or ring-like elements have a width as well as a certain thickness.

[0024] In one example, ten circular rings may form the spoke 102. In another example, more or less than ten circular rings are required to form the spoke 102. As will be understood, the dimensions of the width and thickness of the circular rings as well as the selection of number of rings to form thespoke 102 may depend on various factors like size of the tire, the load that the tire 100 is designed to bear etc.

[0025] In an example, each individual circular ring, also referred to as circular element or simply element, is made up of multiple strands of metal wire with a rubber coating stacked one above the other to form a spiral. In an example embodiment, the metal wire is overlaid 10 times to form the circular element. In another example embodiment, the circular element may be flexible, and lateral force build-up may be achieved by a torsional deformation of the circular elements when a torsional force (steering input) is applied. A counterforce generated due to the torsional deflection provides the selfalignment torque needed for a tire. Particularly, the multiple strands of metal wire are first coated with rubber and then wound in a spiral fashion with one layer above or adjacent the other to form a circular ring-like structure. Accordingly, in an example, the outer surface of the circular ring is made of rubber by coating it with rubber. In an example, metal wire may be stainless steel. The stainless steel possesses adequate load-bearing capacity as well as an appropriate modulus of elasticity. The configuration of the metal wire and the amount of rubber coating required to form the circular ring is based on the size, structural strength, and load-bearing capacity of the tangential nonpneumatic tire 100.

[0026] In one example embodiment, each array of the spoke 102 is first created with circular rings and then placed between the inner band 106 and the outer band 108 of the tangential non-pneumatic tire 100. In an example, there is a single wire coated with rubber which is overlaid to form a ring and the same wire then extends to a second adjacent ring and this goes on, thereby keeping all rings in the spoke 102 intact. Thus, in some examples, all rings in one array of the spoke 102 are made of single long rubber-coated wire without any break. In an example, a rubber layer, referred to as inner bandabove (elaborated below in reference to Fig. 4), may be provided between the rim 104 and the spoke 102 to prevent direct contact of the circular element with the metal rim 104. In another example, the spoke 102 may be placed between the inner band 106 and the outer band 108 of the tangential nonpneumatic tire 100 by curing the spoke 102 that may be carried out at suitable temperature.

[0027] In one example, the spoke 102 may be precisely placed between the inner band 106 and the outer band 108 of the tangential non-pneumatic tire 100 and then cured at a temperature in range of 100°C to 150°C. In an example, the curing may be carried out at a pressure in range of 4 bar to 10 bar. The combination of heat and pressure activates chemical crosslinking in the rubber layer present between the inner band 106 and the outer band 108 which in turn fix the spoke 102 between the inner band 106 and the outer band 108 of the tangential non-pneumatic tire 100.

[0028] Fig. 2 illustrates a cross-sectional view of the array of spokes of the tangential non-pneumatic tire showing two sets of spokes having an offset, in accordance with an implementation of the present subject matter. Fig. 3 illustrates a perspective view of the array of spokes containing two sets of spokes depicting the offset, in accordance with an implementation of the present subject matter. Since Figures 2-3 illustrate an arrangement relationship of a plurality of elements constituting the spoke 102, for the sake of ease of explanation, Figures 2-3 are explained together.

[0029] As shown in Fig. 2, an array of spokes 102 is created by placing one spoke behind the other spoke along the width of the non-pneumatic tire 100. In an example embodiment, a rubber-coated wire flows across all the circular elements in the spoke 102, thereby keeping the circular elements intact. Also, rubber curing of all areas around the spoke 102 between the outer band 108 and the rim 104 helps to keep the circular element as well as the spoke 102itself, intact. In the example implementation shown in Fig. 2, the array of spokes 102 comprises a first spoke 102a and a second spoke 102b along the width of the non-pneumatic tire 100. However, the depicted embodiment with two spokes is not a limitation and various other example implementations with the array of spokes 102 comprising one or multiple layers of spokes along the width of the non-pneumatic tire 100 are possible.

[0030] As shown in Fig. 3, each spoke in the array of spokes 102 is placed laterally and offset to each other. In other words, each spoke is not completely aligned with the other spoke along the width of the non-pneumatic tire, rather the spokes 102 are laterally placed offset to each other. In one example, the offset between the at least two spokes in the array of spokes may be 45°. For instance, as shown in Fig. 3, the first spoke 102a is placed laterally and offset by 45° with respect to the second spoke 102b. In another example implementation, the offset between the at least two spokes in the array of spokes 102 may be 10°. Similarly, in another example implementation, the offset between the at least two spokes in the array of spokes 102 may be 80°. As will be understood, different degrees of offset may be selected depending on various design and load-bearing considerations. This arrangement ensures the deformation of the structural elements for the generation of forces and moments that are needed for the operation of a tire 100 under usage. Further, it also ensures a uniform footprint pressure when the tire rolls over the surface.

[0031] Further, it is also possible that not all spokes are offset with respect to all other spokes in the array. For example, in an array of spokes 102, the first spoke 102a and the second spoke 102b may be offset with respect to each other, while the second spoke 102b and the third spoke (not depicted in Fig. 3) may not be offset with respect to each other. In such an example, the third spoke may align with the first spoke 102a and may be positioned behindthe first spoke 102a without the offset with the second spoke 102b having an offset sandwiched in between the first 102a and the third spoke.

[0032] In accordance with the implementation of the present subject matter, each ring of the spoke 102 has a certain width as mentioned above. The width may be selected in proportion to the width of the tread of the tire 100 or the width of the rim 104. In one example, the number of spokes required in the array of spokes 102 for the tire having a 120 mm tread width is ten.

[0033] Fig. 4 illustrates a cross-sectional view of a tangential nonpneumatic tire. In accordance with an example implementation of the present subject matter.

[0034] As shown in Fig. 4, the array of spokes 102 extend in a circumferential and radial direction of the tire 100 between an inner band 106 and the outer band 108. The inner band 106 interfaces with the rim 104.

[0035] In one example, the outer band 108 comprises a tread layer 110, a under-tread layer 112, and a belt layer 116. The tread layer 110 contacts with a surface during the rotation of the tire 100. The under-tread layer 112 is positioned between the tread layer 110 and the belt layer 116. The belt layer 116 interfaces with the array of spokes 102. The belt layer 116 is made of nylon, polyester, steel, fiberglass, aramid, for example, to keep the array of spokes 102 together and to govern the radial growth of the TNPT structure. This also ensures the tangential stiffness needed for the TNPT to operate in the direction of rotation is achieved without much energy loss and also helps in handling the acceleration and braking torques effectively.

[0036] In another example, the tread layer 110, the under-tread layer 112, and the inner band 106 may be made up of at least one of natural rubber, styrene butadiene rubber (SBR), thermoplastic elastomer (TPE), thermoplastic polyurethane (TPU), fiber glass, a combination thereof, or any suitable material.

[0037] In accordance with the implementation of the present subject matter, a rubber layer is formed everywhere around the circular elements between the inner band 106 and the belt layer 1 16. This rubber is cured to keep the circular element, as well as the spoke 102 intact.

[0038] In one example embodiment, the tangential non-pneumatic tire 100 having a tread width 120 mm may comprise ten spokes to form the array of spokes 102. The metal wire may be overlaid 10 times to form the circular element. The diameter of the wire may be 1 .30 mm.

[0039] In another example embodiment, the tangential non-pneumatic tire 100 is designed for light vehicles, such as passenger cars, two-wheelers, three-wheelers, etc. The tire has an outer diameter ranging from 300 mm to 1500 mm and a tread width ranging from 60 mm to 280 mm.

[0040] Although implementations of a tire are described, it is to be understood that the present subject matter is not necessarily limited to the specific features of the systems described herein. Rather, the specific features are disclosed as implementations for the tire.

Claims

I / We Claim:1 . A tangential non-pneumatic tire (100) comprising: an inner band (106) to interface with a rim (104) of a wheel on which the tire (100) is to be mounted; an outer band (108) separated from the inner band (106) and forming a tread portion of the tire (100); an array of spokes (102) extending in a circumferential and radial direction of the tire (100) between the inner band (106) and the outer band (108), wherein each spoke in the array of spokes (102) comprises: multiple circular rings placed adjacent to each other and connected about their circumference so that centres of the multiple circular rings form a notional circle; and wherein at least two of the spokes in the array of spokes (102) is placed laterally and offset to each other along the width of the tire (100).

2. The tangential non-pneumatic tire (100) as claimed in claim 1 , wherein the outer band (108) comprises a tread layer (110), an under-tread layer (112), and a belt layer (116), wherein: the tread layer (110) contacts with a surface during the rotation of the tire (100); the under-tread layer (112) is positioned between the tread layer (110) and the belt layer (116); and the belt layer (1 16) interfaces with the array of spokes (102).

3. The tangential non-pneumatic tire (100) as claimed in claim 2, wherein the tread layer comprises (110) at least one of natural rubber, styrene butadiene rubber (SBR), thermoplastic elastomer (TPE), thermoplastic polyurethane (TPU), or fiber glass;the under-tread layer (112) comprises at least one of natural rubber, styrene butadiene rubber (SBR), thermoplastic elastomer (TPE), thermoplastic polyurethane (TPU), or fiber glass; and the belt layer (116) comprises at least one of nylon, polyester, steel, fiberglass, or aramid.

4. The tangential non-pneumatic tire (100) as claimed in claim 1 , wherein the inner band (106) comprises at least one of natural rubber, styrene butadiene rubber (SBR), thermoplastic elastomer (TPE), thermoplastic polyurethane (TPU), or fiber glass.

5. The tangential non-pneumatic tire (100) as claimed in claim 1 , wherein each of the circular rings is made up of multiple layers of metal wire combined with a rubber coating.

6. The tangential non-pneumatic tire (100) as claimed in claim 5, wherein the metal wire comprises stainless steel.

7. The tangential non-pneumatic tire (100) as claimed in claim 1 , wherein each of the circular rings is formed from a single continuous rubber-coated wire.

8. The tangential non-pneumatic tire (100) as claimed in claim 1 , wherein the offset between the at least two spokes (102) in the array is between 10° and 80°.

9. The tangential non-pneumatic tire (100) as claimed in claim 1 , wherein the offset between the at least two spokes (102) in the array is 45°.

10. The tangential non-pneumatic tire (100) as claimed in claim 1 , wherein the array comprises ten spokes (102) with each of the spokes (102) having a tread width of 120 mm.11 . The tangential non-pneumatic tire (100) as claimed in claim 1 , wherein the array of spokes (102) is placed between the inner band (106) and the outer band (108) by curing the array of spokes (102) at a predetermined temperature.

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