Non-pneumatic tires

Abstract

To provide a non-pneumatic tire that can reduce pitch noise.SOLUTION: A non-pneumatic tire 1 comprises: an inner annular part 20; an outer annular part 30 arranged on an outer periphery side of the inner annular part 20, concentrically with an outer periphery side of the inner annular part 20; a plurality of spokes 40 arranged along a tire circumferential direction to connect the inner annular part 20 to the outer annular part 30; and a tread 50 provided on an outer peripheral surface of the outer annular part 30. The tread 50 has a tread pattern in which a plurality of pitch elements with different pitch lengths P1 are arranged along the tire circumferential direction in a first arrangement pattern, and the plurality of spokes 40 are arranged along the tire circumferential direction at pitches deviating from pitches of the first arrangement pattern.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a non-pneumatic tire. [Background technology]

[0002] In recent years, non-pneumatic tires have been developed that are free from problems such as punctures and do not require air pressure adjustment. Non-pneumatic tires generally have a structure in which an inner annular portion and an outer annular portion are coaxially arranged and connected by a plurality of spokes. The spokes are arranged radially at intervals around the tire circumference. A tread that comes into contact with the road surface is provided on the outer peripheral surface of the outer annular portion.

[0003] For example, Patent Document 1 discloses a non-pneumatic tire that can improve ride comfort by providing reinforcing portions in the spokes and appropriately setting the area of ​​the reinforcing portions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-43505 A Summary of the Invention [Problem to be solved by the invention]

[0005] This type of non-pneumatic tire generates pitch noise when the tire is running. This pitch noise occurs when the spokes strike the road surface. While the configuration of Patent Document 1 can improve ride comfort, it does not take into consideration pitch noise during running.

[0006] An object of the present invention is to provide a non-pneumatic tire capable of reducing pitch noise. [Means for solving the problem]

[0007] The non-pneumatic tire of the present invention is a non-pneumatic tire comprising an inner annular portion, an outer annular portion arranged coaxially with the inner annular portion on the outer peripheral side of the inner annular portion, a plurality of spokes connecting the inner annular portion and the outer annular portion and arranged along the tire circumferential direction, and a tread provided on the outer peripheral surface of the outer annular portion, wherein the tread has a tread pattern in which a plurality of pitch elements with different pitch lengths are arranged along the tire circumferential direction in a first arrangement pattern, and the plurality of spokes are arranged along the tire circumferential direction at a pitch that is offset from the first arrangement pattern. [Effects of the Invention]

[0008] According to the present invention, a non-pneumatic tire capable of reducing pitch noise can be provided. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a side view showing a non-pneumatic tire according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Figure 3] FIG. 3 is a partial perspective view of a non-pneumatic tire, as seen obliquely from the portion shown in FIG. 2. [Figure 4] FIG. 2 is a development view schematically showing division of pitch elements in a tread pattern. [Figure 5] FIG. 2 is an enlarged view of a V portion in FIG. 1, and is a partial side view of a non-pneumatic tire. [Figure 6] This is a view of the development of Figure 4, seen through the positions of the spoke connections. [Figure 7] FIG. 7 is a diagram corresponding to FIG. 6, showing a modified example of the arrangement of the first arrangement pattern and the second arrangement pattern. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, this embodiment will be described with reference to the drawings. Fig. 1 is a side view of a non-pneumatic tire 1 of this embodiment, viewed from the side in a direction parallel to the tire rotation axis (tire meridian), i.e., in a direction along the front-to-back direction of the paper in Fig. 1. The non-pneumatic tire 1 shown in Fig. 1 is in an unloaded state. Fig. 2 is a cross-sectional view taken along II-II in Fig. 1. Fig. 3 is a partial perspective view of the non-pneumatic tire 1, as viewed obliquely from the portion shown in Fig. 2.

[0011] In Fig. 1 and Fig. 3, arrow C indicates the tire circumferential direction. In Fig. 1 to Fig. 3, arrow X indicates the tire radial direction. In Fig. 2 and Fig. 3, arrow Y indicates the tire width direction. In Fig. 1, the tire width direction Y is the front-to-back direction of the paper. In Fig. 2, symbol E is the tire equatorial plane. In Fig. 2, the tire circumferential direction C is the front-to-back direction of the paper.

[0012] The tire circumferential direction C is a direction around the tire rotational axis and is the same direction as the rotational direction of the non-pneumatic tire 1. The tire radial direction X is a direction perpendicular to the tire rotational axis. The tire width direction Y is a direction parallel to the tire rotational axis. In FIGS. 2 and 3, one side of the tire width direction Y is indicated as Y1, and the other side of the tire width direction Y is indicated as Y2. The tire equatorial plane E shown in FIG. 2 is a plane perpendicular to the tire rotational axis and located at the center of the tire width direction Y. The directions indicated by these symbols are the same in FIGS.

[0013] The non-pneumatic tire 1 of this embodiment includes an inner annular portion 20, an outer annular portion 30, a plurality of spokes 40, and a tread 50. In the following description, the thicknesses of the inner annular portion 20 and the outer annular portion 30 refer to the dimensions in the tire radial direction X. The widths of the inner annular portion 20 and the outer annular portion 30 refer to the dimensions in the tire width direction Y shown in FIG.

[0014] The inner annular portion 20 is an annular portion along the tire circumferential direction C that constitutes the inner circumferential portion of the non-pneumatic tire 1. The thickness and width of the inner annular portion 20 are set to be constant to improve uniformity. A tire wheel (not shown) is placed in the space on the inner circumferential side of the inner annular portion 20. The inner circumferential portion of the inner annular portion 20 is fitted onto the outer circumferential portion of the rim of the tire wheel. The inner annular portion 20 is fitted onto the rim, and the non-pneumatic tire 1 is then fitted onto the tire wheel. The inner circumferential surface of the inner annular portion 20 may be provided with a fitting portion consisting of a protrusion, a groove, etc. for fitting with the rim. The inner annular portion 20 can be made of, for example, a resin material having elasticity, but the material is not limited to resin.

[0015] The inner annular portion 20 transmits the rotation of the tire wheel to the spokes 40 and the outer annular portion 30. The thickness of the inner annular portion 20 is determined from the viewpoint of achieving light weight and durability while fulfilling the function of sufficiently transmitting rotational force to the spokes 40. The thickness of the inner annular portion 20 is not particularly limited, but is preferably 2% to 7% of the tire cross-sectional height H shown in Fig. 2, and more preferably 3% to 6%.

[0016] The inner diameter of the inner annular portion 20 is determined depending on the dimensions of the rim of the tire wheel on which the non-pneumatic tire 1 is mounted, the use of the vehicle, etc. For example, when assuming a replacement for a general pneumatic tire, the inner diameter of the inner annular portion 20 may be, for example, a dimension of 250 mm or more and 500 mm or less, but is not limited to this.

[0017] The width of the inner annular portion 20 is determined appropriately depending on the application of the vehicle on which the non-pneumatic tire 1 is mounted, etc. For example, when assuming a replacement for a general pneumatic tire, the width of the inner annular portion 20 may be, but is not limited to, a dimension of 100 mm or more and 300 mm or less.

[0018] The outer annular portion 30 is an annular portion along the tire circumferential direction C that constitutes the outer periphery of the non-pneumatic tire 1. The outer annular portion 30 is disposed coaxially with the inner annular portion 20 on the outer circumferential side of the inner annular portion 20. The thickness and width of the outer annular portion 30 are set to be constant to improve uniformity. The outer annular portion 30 can be made of, for example, an elastic resin material, but the material is not limited to resin.

[0019] The outer annular portion 30 transmits the rotation of the inner annular portion 20 and the spokes 40 to the road surface via the tread 50. The thickness of the outer annular portion 30 is determined from the viewpoint of achieving light weight and durability while also fulfilling the function of sufficiently transmitting rotational force from the spokes 40 to the road surface. The thickness of the outer annular portion 30 is not particularly limited, but is preferably, for example, 2% to 7% of the tire cross-sectional height H shown in FIG. 2, and more preferably 2% to 5%.

[0020] The inner diameter of the outer annular portion 30 is determined appropriately depending on the dimensions of the rim of the tire wheel on which the non-pneumatic tire 1 is mounted, the use of the vehicle, etc. For example, when assuming a replacement for a general pneumatic tire, the inner diameter of the outer annular portion 30 may be, but is not limited to, a dimension of 420 mm or more and 750 mm or less.

[0021] The width of the outer annular portion 30 is determined appropriately depending on the application of the vehicle on which the non-pneumatic tire 1 is mounted, etc. For example, when assuming a replacement for a general pneumatic tire, the width of the outer annular portion 30 may be, but is not limited to, a dimension of 100 mm or more and 300 mm or less.

[0022] The plurality of spokes 40 connect the inner annular portion 20 and the outer annular portion 30. The inner annular portion 20 and the outer annular portion 30 connected by the plurality of spokes 40 are arranged coaxially with each other. The plurality of spokes 40 are arranged independently along the tire circumferential direction C. As shown in FIG. 1 , when the non-pneumatic tire 1 is in an unloaded state, the plurality of spokes 40 extend linearly in the radial direction substantially parallel to the tire radial direction X in a side view.

[0023] 2 and 3, the multiple spokes 40 of this embodiment include multiple first spokes 41 and multiple second spokes 42. The extension direction of both the first spokes 41 and the second spokes 42 is not parallel to the tire radial direction X when viewed in a direction along the tire circumferential direction C. The first spokes 41 are inclined toward one side in the tire axial direction, i.e., the tire width direction Y. The second spokes 42 are inclined toward the opposite side to the first spokes 41. The first spokes 41 and the second spokes 42 are arranged alternately in the tire circumferential direction C.

[0024] 2 and 3, the first spokes 41 extend at an angle from the Y1 side, which is one side in the tire width direction Y of the outer annular portion 30, toward the Y2 side, which is the other side in the tire width direction Y of the inner annular portion 20. The second spokes 42 extend at an angle from the Y2 side, which is the other side in the tire width direction Y of the outer annular portion 30, toward the Y1 side, which is one side in the tire width direction Y of the inner annular portion 20.

[0025] The inclination angles of the first spokes 41 and the second spokes 42 are the same. Therefore, the first spokes 41 and the second spokes 42 adjacent to each other in the tire circumferential direction C are arranged in a substantially X-shape when viewed from a direction along the tire circumferential direction C. As shown in FIG. 2 , the first spokes 41 and the second spokes 42 are inclined at an angle θ with respect to the tire width direction Y, and the angle θ is preferably, for example, equal to or greater than 30° and equal to or less than 60°.

[0026] 2, when viewed in a direction along the tire circumferential direction C, the first spokes 41 and the second spokes 42 each have the same shape and are symmetrical with respect to the tire equatorial plane E. Therefore, hereinafter, when there is no need to distinguish between the first spokes 41 and the second spokes 42 and they can be described together, the first spokes 41 and the second spokes 42 will be collectively referred to as spokes 40.

[0027] The spokes 40 are plate-shaped and extend obliquely at the angle θ from the inner annular portion 20 toward the outer annular portion 30 as described above. As shown in FIG. 3 , the thickness t of the spokes 40 along the tire circumferential direction is smaller than the width w, and the direction of the thickness t is along the tire circumferential direction C. That is, the spokes 40 are formed in a plate shape extending in the plane of the tire radial direction X and the tire width direction Y. Note that the width w here refers to the dimension in the direction perpendicular to the oblique direction in which the spokes 40 extend when viewed from the direction along the tire circumferential direction C, as also shown in FIG. 2 . In this embodiment, all of the spokes 40 have the same thickness t. All of the spokes 40 also have the same width w.

[0028] Because the spokes 40 are long and plate-shaped, the durability of the spokes 40 can be improved by widening the plate width w even if the plate thickness t is thin. Furthermore, by thinning the plate thickness t and increasing the number of spokes 40, the distance between adjacent spokes 40 in the tire circumferential direction C can be reduced while maintaining the rigidity of the entire non-pneumatic tire 1. This distributes the ground contact pressure of the spokes 40 when the tire rolls, thereby reducing the ground contact pressure. Although the spokes 40 in this embodiment are parallel to the tire radial direction X in a side view, the spokes 40 may be disposed obliquely with respect to the tire radial direction X so as to intersect with the tire radial direction X in a side view.

[0029] 2 and 3 , the first spoke 41 has a first inner connection portion 411 connected to the tire width direction Y2 side of the inner annular portion 20, and a first outer connection portion 412 connected to the tire width direction Y1 side of the outer annular portion 30. The second spoke 42 has a second inner connection portion 421 connected to the tire width direction Y1 side of the inner annular portion 20, and a second outer connection portion 422 connected to the tire width direction Y2 side of the outer annular portion 30. The first outer connection portion 412 and the second outer connection portion 422 are each an example of a connection portion of the spoke 40 connected to the outer annular portion 30 in this embodiment.

[0030] 2, the first inner connection portion 411 of the first spoke 41 has a shape that widens in the tire width direction Y as it approaches the inner annular portion 20. A side surface 411a on the tire width direction Y2 side of the first inner connection portion 411 extends while gently curving to an end portion 20b of the inner annular portion 20 on the tire width direction Y2 side. A side surface 411b on the tire width direction Y1 side of the first inner connection portion 411 extends while curving toward the tire width direction Y1 side to the position of the tire equatorial plane E of the inner annular portion 20.

[0031] The first outer connection portion 412 of the first spoke 41 has a shape similar to that of the first inner connection portion 411, and has a shape that widens in the tire width direction as it approaches the outer annular portion 30. A side surface 412a on the tire width direction Y1 side of the first outer connection portion 412 extends while gently curving to an end portion 30a of the outer annular portion 30 on the tire width direction Y1 side. A side surface 412b on the tire width direction Y2 side of the first outer connection portion 412 extends while curving toward the tire width direction Y2 to the position of the tire equatorial plane E of the outer annular portion 30. The first inner connecting portion 411 is provided in a half region on the tire width direction Y2 side of the inner annular portion 20. The first outer connecting portion 412 is provided in a half region on the tire width direction Y1 side of the outer annular portion 30.

[0032] 2, the second inner connection portion 421 of the second spoke 42 has a shape that widens in the tire width direction Y as it approaches the inner annular portion 20. A side surface 421a on the tire width direction Y1 side of the second inner connection portion 421 extends while gently curving to an end portion 20a of the inner annular portion 20 on the tire width direction Y1 side. A side surface 421b on the tire width direction Y2 side of the second inner connection portion 421 extends while curving toward the tire width direction Y2 to the position of the tire equatorial plane E of the inner annular portion 20.

[0033] The second outer connection portion 422 of the second spoke 42 has a shape similar to that of the second inner connection portion 421, and has a shape that widens in the tire width direction as it approaches the outer annular portion 30. A side surface 422a on the tire width direction Y2 side of the second outer connection portion 422 extends while gently curving to an end portion 30b on the tire width direction Y2 side of the outer annular portion 30. A side surface 422b on the tire width direction Y1 side of the second outer connection portion 422 extends while curving toward the tire width direction Y1 side to the position of the tire equatorial plane E of the outer annular portion 30. The second inner connecting portion 421 is provided in a half region on the tire width direction Y1 side of the inner annular portion 20. The second outer connecting portion 422 is provided in a half region on the tire width direction Y2 side of the outer annular portion 30.

[0034] As described above, in this embodiment, all of the spokes 40 have the same thickness t. The dimension of the thickness t is not particularly limited, but is preferably 1 mm or more and 30 mm or less, and more preferably 5 mm or more and 25 mm or less, so that the spokes 40 can sufficiently withstand the rotational force from the inner annular portion 20 and the outer annular portion 30 and can be appropriately flexibly deformed when subjected to a load.

[0035] As described above, all spokes 40 in this embodiment have the same width w. The width w of the spokes 40 is not particularly limited, but is preferably 5 mm or more and 25 mm or less, and more preferably 10 mm or more and 20 mm or less, so as to be able to adequately withstand rotational forces from the inner annular portion 20 and the outer annular portion 30 while being able to flex and deform appropriately when subjected to a load. Furthermore, the width w is preferably 110% or more of the thickness t, and more preferably 115% or more, from the viewpoint of being able to distribute ground pressure while improving durability.

[0036] The number of spokes 40 is preferably 80 to 300, and more preferably 100 to 200, from the viewpoint of being able to adequately support the load from the vehicle while being lightweight and achieving both improved power transmission and durability.

[0037] The spokes 40 can be made of any of the following elastic materials. First, in terms of the properties of the elastic material, from the viewpoint of imparting appropriate rigidity while ensuring sufficient durability, it is preferable that the tensile modulus calculated from the tensile stress at 10% elongation in a tensile test conducted in accordance with JIS K7312:1996 be 3 MPa or more and 12 MPa or less.

[0038] If the tensile modulus of the spokes 40 calculated from the tensile stress at 10% elongation is less than 3 MPa, sufficient rigidity cannot be obtained, and there is a possibility that adjacent spokes 40 in the tire circumferential direction C may come into contact with each other. On the other hand, if the tensile modulus calculated from the tensile stress at 10% elongation exceeds 12 MPa, the rigidity becomes excessively high, resulting in a deterioration in ride comfort.

[0039] The elastic material used as the base material of the spokes 40 may be a thermoplastic elastomer, a crosslinked rubber, or other resin.

[0040] Examples of thermoplastic elastomers include polyester elastomers, polyolefin elastomers, polyamide elastomers, polystyrene elastomers, polyvinyl chloride elastomers, and polyurethane elastomers.

[0041] The rubber material constituting the crosslinked rubber can be either natural rubber or synthetic rubber. Examples of synthetic rubber include styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IIR), nitrile rubber (NBR), hydrogenated nitrile rubber (hydrogenated NBR), chloroprene rubber (CR), ethylene propylene rubber (EPDM), fluororubber, silicone rubber, acrylic rubber, and urethane rubber. Two or more of these rubber materials may be used in combination as needed.

[0042] Other resins include thermoplastic resins and thermosetting resins. Thermoplastic resins include polyethylene resins, polystyrene resins, polyvinyl chloride resins, etc. Thermosetting resins include epoxy resins, phenolic resins, polyurethane resins, silicone resins, polyimide resins, melamine resins, etc.

[0043] Of the above elastic materials, polyurethane resin is preferably used for the spokes 40 from the viewpoints of moldability, processability, and cost. However, foamed materials can also be used as the elastic material. That is, foamed materials made from the above thermoplastic elastomers, crosslinked rubbers, and other resins can be used.

[0044] The elastic material used as the base material of the spokes 40 may be reinforced with reinforcing fibers. Examples of reinforcing fibers include long fibers, short fibers, woven fabrics, and nonwoven fabrics. Examples of reinforcing fibers include rayon cords, polyamide cords such as nylon-6,6, polyester cords such as polyethylene terephthalate, aramid cords, glass fiber cords, carbon fibers, and steel cords.

[0045] The reinforcement of the elastic material is not limited to reinforcement with reinforcing fibers. For example, reinforcement may be performed by adding a granular filler. Examples of the granular filler to be added include carbon black, ceramics such as silica and alumina, and other inorganic fillers.

[0046] Incidentally, it is preferable that the inner annular portion 20 and the outer annular portion 30 are formed from the same resin material as the spokes 40. In this case, the inner annular portion 20, the outer annular portion 30 and the spokes 40 can be integrally molded, for example, by a casting molding method.

[0047] The tread 50 is provided on the outer peripheral surface of the outer annular portion 30 . The tread 50 forms the outermost peripheral portion of the non-pneumatic tire 1. The tread 50 includes tread rubber 51. The tread rubber 51 has a tread surface 51a on its outer peripheral surface that comes into contact with the road surface. There are no particular restrictions on the type of rubber material for the tread rubber 51, and general vulcanized rubber, etc., used for forming the tread of a vehicle tire, can be used. The tread surface 51a of the tread rubber 51 is provided with a tread pattern formed of a plurality of grooves and land portions, similar to that of a conventional pneumatic tire. The tread rubber 51 may have a structure in which a plurality of rubber layers with different components or properties are laminated (for example, two or three layers). The tread 50 may also be made of resin.

[0048] The non-pneumatic tire 1 of the present embodiment may further include a reinforcing layer (not shown). The reinforcing layer may be embedded in the outer annular portion 30. Alternatively, the reinforcing layer may be provided between the outer annular portion 30 and the tread 50. The reinforcing layer is a cylindrical layer extending along the tire circumferential direction C.

[0049] The reinforcing layer is arranged evenly around the entire circumference of the tire to suppress the occurrence of buckling, in which the outer annular portion 30 bends in the tire radial direction X at the center in the tire width direction Y. The reinforcing layer is configured, for example, by arranging steel cords so that they are generally parallel to the tire width direction Y. The reinforcing layer may be a cylindrical metal ring, a high-modulus resin ring, or the like. For example, the reinforcing layer may be a ring made of fiber-reinforced plastic (FRP), such as carbon fiber-reinforced plastic (CFRP) or glass fiber-reinforced plastic (GFRP). By providing the reinforcing layer, the rigidity of the non-pneumatic tire 1 is ensured, and the contact of the tread 50 with the road surface is improved.

[0050] Fig. 4 is a development view that schematically shows division of pitch elements in the tread pattern of the tread 50. In Fig. 4, the up-down direction on the paper surface is the tire circumferential direction C, and the left-right direction on the paper surface is the tire width direction Y. Fig. 4 corresponds to a view of a part of the outer surface of the tread 50 in the V-section region of Fig. 1, for example, as viewed from the outer periphery of the tire.

[0051] The tread 50 has a tread pattern in which a plurality of pitch elements (constituent units of the pattern) having different pitch lengths P1 are arranged in a first arrangement pattern along the tire circumferential direction C.

[0052] The first arrangement pattern of this embodiment is a pattern in which patterns TS, TM, and TL as multiple pitch elements are arranged at a so-called variable pitch. Here, variable pitch means that the pitch elements that are repeatedly used are arranged with different pitch lengths P1. The pitch length P1 in the first arrangement pattern is defined by the tire circumferential length of the patterns TS, TM, and TL as pitch elements. It is preferable that the multiple pitch elements of the tread pattern are arranged at a variable pitch having at least three or more different pitch lengths P1.

[0053] The first arrangement pattern of this embodiment includes a plurality of pitch elements having at least three different pitch lengths P1. Specifically, the pitch lengths P1 of the pitch elements constituting the first arrangement pattern include at least three types: pitch length S1, pitch length M1 longer than pitch length S1, and pitch length L1 longer than pitch length M1. That is, the first arrangement pattern includes pitch elements TS having pitch length S1, pitch elements TM having pitch length M1 longer than pitch length S1, and pitch elements TL having pitch length L1 longer than pitch length M1. These multiple pitch elements having different pitch lengths P1 are distributed and arranged in the tire circumferential direction C. In this embodiment, as shown in FIG. 4, the pitch elements are arranged in the order TL, TM, TS, TS, TM, TL. In this manner, it is preferable that the multiple pitch elements having different pitch lengths P1 are arranged irregularly in the tire circumferential direction.

[0054] The first arrangement pattern of this embodiment includes an arrangement order in which a first pitch element, a second pitch element adjacent to the first pitch element and having a pitch length different from that of the first pitch element, and a third pitch element adjacent to the second pitch element and having a pitch length different from that of the second pitch element are arranged in this order. For example, the first arrangement pattern includes an arrangement order in which a pitch element TL with a pitch length L1, a pitch element TM adjacent to the pitch element TL with a pitch length M1 different from the pitch length L1 of the pitch element TL, and a pitch element TS adjacent to the pitch element TM with a pitch length S1 different from the pitch length M1 of the pitch element TM are arranged. The first arrangement pattern may include an arrangement order in which a first pitch element, a second pitch element arranged adjacent to the first pitch element and having a pitch length different from that of the first pitch element, a third pitch element arranged adjacent to the second pitch element and having a pitch length different from that of the second pitch element, and a fourth pitch element arranged adjacent to the third pitch element and having a pitch length different from that of the third pitch element, are arranged in this order. In this case, non-adjacent pitch elements, for example, the second pitch element and the fourth pitch element, may have the same pitch length. By including such a configuration, the frequency components of pitch noise during tire rotation can be effectively dispersed. During tire rotation, noise with frequencies corresponding to the arrangement of pitch elements in the tread pattern can be problematic. However, according to this embodiment, the pitch noise frequency during tire rotation can be dispersed, thereby reducing pitch noise caused by the arrangement of pitch elements in the tread pattern.

[0055] Fig. 5 is an enlarged view of the V portion of Fig. 1, and is a partial side view of a non-pneumatic tire. Fig. 6 is a perspective view of the positions of the connection portions of the spokes 40 connected to the inner circumferential surface of the outer annular portion 30, as compared to the developed view schematically showing the tread pattern of Fig. 4. That is, Fig. 6 is a view showing the relationship between the first arrangement pattern and the second arrangement pattern, and is a view showing by dashed lines the imaginary positions of the connection portions of the spokes 40 projected onto the surface of the tread pattern.

[0056] The multiple spokes 40 are arranged along the tire circumferential direction C at a pitch that is shifted from the first arrangement pattern of the tread pattern. Specifically, the connection portions 412, 422 of the multiple spokes 41, 42 are arranged along the tire circumferential direction C at different pitch lengths P2 in a second arrangement pattern that has a pitch that is shifted from the first arrangement pattern of the tread pattern.

[0057] In this embodiment, the first spokes 41 and the second spokes 42 are arranged alternately in the tire circumferential direction. Therefore, the pitch length P2 of the connection portions of the multiple spokes 40 is determined based on the position of the first outer connection portion 412 of the first spoke 41 and the position of the second outer connection portion 422 of the second spoke 42 adjacent to the first outer connection portion 412 of the first spoke 41.

[0058] In this embodiment, the connection portions of the multiple spokes 40 are arranged along the tire circumferential direction C at a so-called variable pitch. In other words, the second arrangement pattern is a variable pitch arrangement pattern. Here, variable pitch means that the connection portions of the spokes 40, as a pitch element, are arranged with different pitch lengths P2. Note that the pitch length P2 in the second arrangement pattern is defined as the tire circumferential length between the center positions in the tire circumferential direction C of the connection portions of adjacent spokes 40. In other words, when the distance between the connection portions of two adjacent spokes 40 in the tire circumferential direction C is defined as the inter-spoke spacing G (described below), the pitch length P2 is the sum of the inter-spoke spacing G, half the length of the dimension corresponding to the plate thickness t of the connection portion of the spokes 40 on one side adjacent to the inter-spoke spacing G, and half the length of the dimension corresponding to the plate thickness t of the connection portion of the spokes 40 on the other side adjacent to the inter-spoke spacing G.

[0059] The connection portions of the plurality of spokes 40 are arranged at a variable pitch having a plurality of pitch lengths P2 that are deviated from the variable pitch of the tread pattern. It is preferable that the connection portions of the plurality of spokes 40 are arranged at a variable pitch having at least three or more different pitch lengths P2 that are deviated from the variable pitch of the tread pattern.

[0060] The second arrangement pattern of this embodiment has at least three or more pitch lengths P2. Specifically, the pitch lengths P2 constituting the second arrangement pattern include at least three types: pitch length S2, pitch length M2 longer than pitch length S2, and pitch length L2 longer than pitch length M2. These different pitch lengths P2 are distributed and arranged in the tire circumferential direction C. In this embodiment, as shown in FIG. 5, the pitch lengths P2 are arranged in the order of M2, S2, M2, L2, M2, S2. In this manner, it is preferable that the different pitch lengths are arranged irregularly in the tire circumferential direction. Note that FIG. 6 shows M3, S3, M3, L3, M3, S3 as virtual pitch lengths P3 when the pitch lengths P2 shown in FIG. 5, M2, S2, M2, L2, M2, S2, are projected onto the surface of the tread 50.

[0061] The second arrangement pattern of this embodiment includes an arrangement order in which a first pitch, a second pitch adjacent to the first pitch and having a pitch length different from the first pitch, and a third pitch adjacent to the second pitch and having a pitch length different from the second pitch are arranged in this order. For example, the second arrangement pattern includes an arrangement order in which a first pitch with a pitch length S2, a second pitch adjacent to the first pitch and having a pitch length M2 different from the pitch length S2, and a third pitch adjacent to the second pitch and having a pitch length L2 different from the pitch length M2 are arranged in this order. The second arrangement pattern may include an arrangement order in which a first pitch (e.g., a pitch with a pitch length of S2), a second pitch adjacent to the first pitch and having a different pitch length (e.g., a pitch length of M2) from the first pitch, a third pitch adjacent to the second pitch and having a different pitch length (pitch length L2) from the second pitch, and a fourth pitch adjacent to the third pitch and having a different pitch length (pitch length M2) from the third pitch. Note that in this case, the pitch lengths of non-adjacent pitches, for example, the second pitch and the fourth pitch, may be the same. By including such a configuration, it is possible to effectively disperse the frequency components of pitch noise during tire rotation. During tire rotation, noise with a frequency corresponding to the arrangement position of the outer connection portion of the spokes becomes a problem. However, according to this embodiment, it is possible to disperse the frequency of pitch noise during tire rotation and reduce pitch noise generated when the spokes 40 strike the road surface.

[0062] In addition, the connection portions of the multiple spokes 40 in this embodiment are arranged with different pitch lengths P2 along the tire circumferential direction C by varying the spoke spacing G, which is the distance between adjacent connection portions in the tire circumferential direction C.

[0063] As shown in FIG. 5 , in the non-pneumatic tire 1 of this embodiment, the spacing G between adjacent spokes 40 in the tire circumferential direction C is non-uniform. Note that in the following description, the spacing G between the spokes 40 will be referred to as the inter-spoke spacing G. In this embodiment, the inter-spoke spacing G is the distance between the first outer connection portion 412 of the first spoke 41 and the second outer connection portion 422 of the second spoke 42 that are adjacent in the tire circumferential direction C. More specifically, as shown in FIG. 5 , the inter-spoke spacing G is the distance in the tire circumferential direction C between a first outer peripheral end 412 c on the second outer connection portion 422 side of the boundary of the first outer connection portion 412 with the inner circumferential surface of the outer annular portion 30 and a second outer peripheral end 422 c on the first outer connection portion 412 side of the boundary of the second outer connection portion 422 with the inner circumferential surface of the outer annular portion 30.

[0064] The inter-spoke spacing G in this embodiment includes at least three types: spacing S, spacing M longer than spacing S, and spacing L longer than spacing M. These three types of inter-spoke spacing G are distributed in the tire circumferential direction C. In other words, the inter-spoke spacing G, which indicates the gap between the first outer peripheral end 412c of the first outer connection portion 412 and the second outer peripheral end 422c of the second outer connection portion 422 that are adjacent in the tire circumferential direction C, is arranged irregularly in the tire circumferential direction C such that the three types of spacing S, spacing M, and spacing L are not periodic around the entire circumference of the tire 1. This makes it easy to arrange the connection portions of multiple spokes 40 with different pitch lengths P2 along the tire circumferential direction, even when the plate thickness of the spokes 40 is constant.

[0065] The spoke spacing G is preferably set to be equal to or greater than 2 mm and equal to or less than 30 mm. The spoke spacing G may be, for example, but is not limited to, spacing S of 7 mm, spacing M of 9 mm, and spacing L of 11 mm. It is preferable that the tensile modulus calculated from the tensile stress at 10% elongation of the spokes 40 be 3 MPa or greater, and that the minimum spoke spacing G be 2.5 mm or greater. This can prevent contact between spokes 40 adjacent in the tire circumferential direction C. As a result, a decrease in tire durability due to spoke damage can be prevented.

[0066] In this embodiment, the spoke spacing G includes an arrangement order of a first spacing, a second spacing adjacent to the first spacing and a different distance from the first spacing, and a third spacing adjacent to the second spacing and a different distance from the second spacing. For example, the spoke spacing G includes an arrangement order of a spacing S, a spacing M adjacent to spacing S and a different distance from spacing S, and a spacing L adjacent to spacing M and a different distance from spacing M. The spoke spacing G may also include an arrangement order of a first spacing (e.g., spacing S), a second spacing (spacing M) adjacent to the first spacing and a different distance from the first spacing, a second spacing (spacing L) adjacent to the second spacing and a different distance from the second spacing, and a fourth spacing (spacing M) adjacent to the third spacing and a different distance from the third spacing. By including such a configuration, the frequency components of pitch noise during tire rotation can be effectively dispersed.

[0067] It is preferable that the arrangement order of the pitch lengths P1 of the multiple pitch elements defined by the first arrangement pattern be different from the arrangement order of the pitch lengths P2 of the connection portions of the multiple spokes defined by the second arrangement pattern. For example, in this embodiment, the arrangement order of the pitch lengths P1 of the multiple pitch elements defined by the first arrangement pattern is L1, M1, S1, S1, M1, L1, and the arrangement order of the pitch lengths P2 of the connection portions of the multiple spokes defined by the second arrangement pattern is M2, S2, M2, L2, M2, S2. The magnitude relationship between the arrangement order of these pitch lengths is different.

[0068] In addition, if the pitch based on the angle relative to the tire rotation axis is expressed as angular pitch, the connection points of the multiple spokes 40 can also be expressed as being arranged along the tire circumferential direction in a second arrangement pattern with an angular pitch different from the angular pitch based on the first arrangement pattern.

[0069] In this embodiment, the tread 50 has a tread pattern in which a plurality of pitch elements having different pitch lengths P1 are arranged in a first arrangement pattern along the tire circumferential direction C. The plurality of spokes 40 are arranged along the tire circumferential direction at a pitch that is shifted from the first arrangement pattern. This makes it possible to comprehensively disperse the frequency components of pitch noise based on the tread pattern and the arrangement pattern of the spokes 40 when the tire is rolling, thereby significantly reducing pitch noise.

[0070] Figure 7, which corresponds to Figure 6, illustrates a specific example of this embodiment, showing a modified example of the arrangement of the first arrangement pattern and the second arrangement pattern. Figure 7 shows a specific example of a tread pattern as the first arrangement pattern. The surface of the tread 50 shown in Figure 7 is provided with a plurality of grooves, including a center main groove 52A, a center lateral groove 52B, a shoulder main groove 52C, a shoulder lateral groove 52D, and a narrow groove 52E.

[0071] The first arrangement pattern of this modified example is a pattern in which patterns TSA, TSB, TMA, TMB, TLA, and TLB as a plurality of pitch elements are arranged at a so-called variable pitch.

[0072] Specifically, the first arrangement pattern of this modified example includes pitch elements TSA and TSB having a pitch length S1, pitch elements TMA and TMB having a pitch length M1 longer than the pitch length S1, and pitch elements TLA and TLB having a pitch length L1 longer than the pitch length M1. These multiple pitch elements having different pitch lengths are distributed and arranged in the tire circumferential direction C. In this modified example, as shown in FIG. 7, the pitch elements are arranged in the following order: TLA, TLB, TLA, TLB, TMA, TMB, TMA, TMB, TSA, TSB, TSA, TSB. For example, a group of pitch elements arranged in this manner may be arranged at another position on the tire outer periphery or may be arranged repeatedly.

[0073] The connection portions of the plurality of spokes 40 in this modified example are arranged at a variable pitch having a plurality of pitch lengths that are shifted from the variable pitch of the tread pattern.

[0074] Specifically, as shown in Fig. 7 , the multiple spokes 40 of this modified example are arranged in the tire circumferential direction C at a pitch that is offset from the first arrangement pattern of the tread pattern, TLA, TLB, TLA, TLB, TMA, TMB, TMA, TMB, TSA, TSB, TSA, TSB. That is, the connection portions of the multiple spokes 40 are arranged in the tire circumferential direction C in a second arrangement pattern having a pitch length that is offset from the pitch length order of the first arrangement pattern, L1, L1, L1, L1, M1, M1, M1, M1, S1, S1, S1, S1. Note that Fig. 7 shows S3, S3, M3, M3, L3, L3 as a virtual pitch length P3 when the pitch lengths of the connection portions of the multiple spokes 40 arranged in the first arrangement pattern are projected onto the surface of the tread 50.

[0075] In this embodiment, the first spokes 41 and the second spokes 42 are also arranged alternately in the tire circumferential direction. Therefore, the pitch length of the connection portions of the multiple spokes 40 is determined based on the position of the first outer connection portion 412 of the first spoke 41 and the position of the second outer connection portion 422 of the second spoke 42 adjacent to the first outer connection portion 412 of the first spoke 41.

[0076] In the first arrangement pattern of this modified example, the set of TLA and TLB, the set of TMA and TMB, and the set of TSA and TSB can each be regarded as a single set of pitch elements. Also, the set of TLA, TLB, TLA and TLB, the set of TMA, TMB, TMA and TMB, and the set of TSA, TSB, TSA and TSB can each be regarded as a single set of pitch elements. Even in this case, the tread 50 has a tread pattern in which a plurality of pitch elements with different pitch lengths P1 are arranged in the tire circumferential direction C in the first arrangement pattern, and the plurality of spokes 40 are arranged in the tire circumferential direction at a variable pitch that is shifted from the first arrangement pattern.

[0077] As described above, in this modified example, the tread 50 also has a tread pattern in which a plurality of pitch elements with different pitch lengths are arranged in a first arrangement pattern along the tire circumferential direction C. The plurality of spokes 40 are arranged along the tire circumferential direction at a pitch that is shifted from the first arrangement pattern. This makes it possible to comprehensively disperse the frequency components of pitch noise based on the tread pattern and the arrangement pattern of the spokes 40 when the tire is rolling, thereby significantly reducing pitch noise.

[0078] The non-pneumatic tire 1 of this embodiment provides the following effects.

[0079] (1) The non-pneumatic tire 1 of this embodiment is a non-pneumatic tire 1 comprising an inner annular portion 20, an outer annular portion 30 arranged coaxially with the inner annular portion 20 on the outer peripheral side of the inner annular portion 20, a plurality of spokes 40 connecting the inner annular portion 20 and the outer annular portion 30 and arranged along the tire circumferential direction, and a tread 50 provided on the outer peripheral surface of the outer annular portion 30, wherein the tread 50 has a tread pattern in which a plurality of pitch elements having different pitch lengths P1 are arranged along the tire circumferential direction in a first arrangement pattern, and the plurality of spokes 40 are arranged along the tire circumferential direction at a pitch that is offset from the first arrangement pattern.

[0080] This makes it possible to reduce pitch noise.

[0081] (2) In the non-pneumatic tire 1 of this embodiment, each of the multiple spokes 40 has a connection portion 412, 422 that connects to the outer annular portion 30, and the connection portions 412, 422 of the multiple spokes are arranged in a second arrangement pattern having a pitch offset from the first arrangement pattern, with different pitch lengths P2 along the tire circumferential direction.

[0082] This allows for further reduction in pitch noise.

[0083] (3) In the non-pneumatic tire 1 of this embodiment, the second arrangement pattern includes an arrangement order in which a first pitch, a second pitch arranged adjacent to the first pitch and having a pitch length different from that of the first pitch, and a third pitch arranged adjacent to the second pitch and having a pitch length different from that of the second pitch are arranged in that order.

[0084] This disperses the frequency of pitch noise when the tire rolls, and further reduces pitch noise caused by the spokes 40 striking the road surface.

[0085] (4) In the non-pneumatic tire 1 of this embodiment, the multiple pitch elements of the tread pattern are arranged at a variable pitch having at least three or more different pitch lengths P1, and the connection portions of the multiple spokes 40 are arranged at a variable pitch having at least three or more different pitch lengths P2 that are shifted from the variable pitch of the tread pattern.

[0086] This allows for further reduction in pitch noise.

[0087] (5) In the non-pneumatic tire 1 of this embodiment, the arrangement order of the pitch lengths P1 of the multiple pitch elements defined by the first arrangement pattern is different from the arrangement order of the pitch lengths P2 of the connection portions of the multiple spokes 40 defined by the second arrangement pattern.

[0088] This allows for further reduction in pitch noise.

[0089] (6) In the non-pneumatic tire 1 of this embodiment, the connection portions of the multiple spokes 40 are arranged with different pitch lengths P2 along the tire circumferential direction by varying the spoke spacing G, which is the distance between adjacent connection portions in the tire circumferential direction.

[0090] This makes it easy to arrange the connection portions of the multiple spokes 40 at different pitch lengths along the tire circumferential direction, even if the plate thickness of the spokes 40 is constant.

[0091] (7) In the non-pneumatic tire 1 of this embodiment, the spokes 40 include a first spoke 41 inclined to one side in the tire axial direction and a second spoke 42 inclined to the opposite side from the first spoke 41, and the first spokes 41 and the second spokes 42 are arranged alternately in the tire circumferential direction, and the pitch length P2 of the connection portion of the multiple spokes 40 is determined based on the position of the connection portion of the first spoke 41 and the position of the connection portion of the second spoke 42 adjacent to the connection portion of the first spoke 41.

[0092] As a result, the first spokes 41 and the second spokes 42 are arranged in a substantially X-shape when viewed from a direction along the tire circumferential direction C. Because the first spokes 41 and the second spokes 42 are each inclined toward the tire axial direction, excessive rigidity is prevented, thereby improving ride comfort.

[0093] In the non-pneumatic tire 1 of this embodiment, the connection portions of the multiple spokes 40 are arranged in an arrangement pattern that deviates from the tread pattern, with different pitch lengths P2 along the tire circumferential direction C, and the tensile modulus calculated from the tensile stress at 10% elongation of the spokes 40 is 3 MPa or more and 12 MPa or less. Furthermore, the spokes 40 are configured such that the first spokes 41 and the second spokes 42 are arranged in a substantially X-shape when viewed from the direction along the tire circumferential direction C. This reduces pitch noise while preventing adjacent spokes 40 from contacting each other, and also maintains a good ride comfort.

[0094] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and any modifications and improvements made within the scope of the present invention are included within the scope of the present invention. For example, the pitch length P1 of the first arrangement pattern is not limited to three types, namely, pitch length S1, pitch length M1, and pitch length L1, but may have at least two types of pitch lengths set, or may have four or more types. The pitch length P2 of the second arrangement pattern is not limited to three types, namely, pitch length S2, pitch length M2, and pitch length L2, but may have at least two types of pitch lengths set, or may have four or more types. That is, the first arrangement pattern preferably includes at least a first pitch element and a second pitch element having a pitch length different from that of the first pitch element, and the first pitch element and the second pitch element are arranged so as not to be periodic.The pitch length of the second arrangement pattern preferably includes at least the first pitch length and a second pitch length longer than the first pitch length, and the connection portions of the spokes 40 are arranged so that the portions forming the first pitch length and the portions forming the second pitch length are not periodic. The spokes 40 include a first spoke 41 and a second spoke 42 that intersect in an approximately X-shape when viewed along the tire circumferential direction C, but the spokes 40 are not limited to this and may be composed of a plate-shaped portion that extends straight in the tire radial direction X. The thickness t and width w of the spokes 40 do not have to be constant; for example, the thickness t and width w may gradually increase from the inner annular portion 20 toward the outer annular portion 30. [Explanation of symbols]

[0095] 1 Non-pneumatic tires 20 Inner annular portion 30 Outer annular part 40 spokes 41 First Spoke 42 Second Spoke 412 First outer connection part (connection part) 422 Second outer connection (connection) 50 tread C Circumferential direction of tire Y Tire width direction

Claims

1. an inner annular portion; an outer annular portion disposed coaxially with the inner annular portion on an outer peripheral side of the inner annular portion; a plurality of spokes that connect the inner annular portion and the outer annular portion and are arranged along the tire circumferential direction; a tread provided on an outer peripheral surface of the outer annular portion, The tread has a tread pattern in which a plurality of pitch elements having different pitch lengths are arranged in a first arrangement pattern along the tire circumferential direction, the plurality of spokes are arranged along the tire circumferential direction at a pitch that is shifted from the first arrangement pattern, Each of the plurality of spokes has a connecting portion that connects to the outer annular portion, a second arrangement pattern having a pitch offset from that of the first arrangement pattern, and the connection portions of the spokes are arranged at different pitch lengths along the circumferential direction of the tire.

2. 2. The non-pneumatic tire of claim 1, wherein the second arrangement pattern includes an arrangement sequence of a first pitch, a second pitch adjacent to the first pitch and having a pitch length different from that of the first pitch, and a third pitch adjacent to the second pitch and having a pitch length different from that of the second pitch.

3. The plurality of pitch elements of the tread pattern are arranged at variable pitches having at least three or more different pitch lengths, 3. The non-pneumatic tire according to claim 1, wherein said spokes are arranged at connection portions at a variable pitch having at least three or more different pitch lengths that are offset from the variable pitch of said tread pattern.

4. 4. The non-pneumatic tire according to claim 1, wherein the arrangement order of the pitch lengths of the plurality of pitch elements defined by the first arrangement pattern is different from the arrangement order of the pitch lengths of the connection portions of the plurality of spokes defined by the second arrangement pattern.

5. 5. The non-pneumatic tire according to claim 1, wherein the connection portions of the plurality of spokes are arranged at different pitch lengths along the tire circumferential direction by varying the inter-spoke spacing, which is the distance between the connection portions adjacent in the tire circumferential direction.

6. The spokes are a first spoke inclined toward one side in the tire axial direction; a second spoke inclined opposite to the first spoke; the first spokes and the second spokes are arranged alternately in the tire circumferential direction, 6. The non-pneumatic tire according to claim 1, wherein the pitch length of the connection portions of the plurality of spokes is determined based on the position of a first spoke connection portion and the position of a second spoke connection portion adjacent to the first spoke connection portion.

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