Non-pneumatic tires

Abstract

To provide a non-pneumatic tire that can reduce pitch noise.SOLUTION: A non-pneumatic tire comprises: an inside annular part 20; an outside annular part 30 arranged at an outer periphery side of the inside annular part 20 concentrically with the inside annular part 20; a plurality of spokes 40 arranged in a tire circumferential direction D while connecting the inside annular part 20 to the outside annular part 30; and a tread 50 provided on an outer peripheral surface of the outside annular part 30, where inter-spoke intervals G which are intervals between the spokes 40 adjacently arranged in the tire circumferential direction D are unequal.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] In recent years, non-pneumatic tires that do not cause problems such as punctures and do not require air pressure adjustment have been developed. Generally, a non-pneumatic tire has a structure in which an inner circumferential annular portion and an outer circumferential annular portion arranged coaxially are connected by a plurality of spokes. The plurality of spokes are arranged radially at intervals in the tire circumferential direction. A tread that contacts 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 in which a reinforcing portion is provided on a spoke and the riding comfort can be improved by appropriately setting the area of the reinforcing portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] This type of non-pneumatic tire generates pitch noise during running. This pitch noise occurs when the spoke strikes the road surface. According to the configuration of Patent Document 1, although the riding comfort can be improved, the pitch noise during running is not considered.

[0006] Therefore, an object of the present invention is to provide a non-pneumatic tire capable of reducing pitch noise.

Means for Solving the Problems

[0007] The present invention relates to a non-pneumatic tire comprising an inner annular portion, an outer annular portion arranged coaxially on the outer circumference 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 circumferential surface of the outer annular portion, wherein the spacing between adjacent spokes in the tire circumferential direction is non-uniform. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a non-pneumatic tire that can reduce pitch noise. [Brief explanation of the drawing]

[0009] [Figure 1] This is a side view showing a non-pneumatic tire of the first embodiment. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] Figure 2 is a perspective view of a portion of a non-pneumatic tire, seen from an oblique angle. [Figure 4] This is an enlarged view of section IV in Figure 1, and is a partial side view of a non-pneumatic tire. [Figure 5] This is an unfolded view showing the inner circumferential surface of the outer annular portion of a non-pneumatic tire according to the first embodiment, and is a diagram for explaining the spacing in the tire circumferential direction of the spoke connection portions connected to the inner circumferential surface. [Figure 6] This is a partial side view of a non-pneumatic tire according to the second embodiment, and corresponds to Figure 4. [Figure 7] This is an exploded view showing the inner circumferential surface of the outer annular portion of a non-pneumatic tire according to a second embodiment, and is a diagram for explaining the tire circumferential spacing and tire circumferential dimensions of the spokes connected to the inner circumferential surface. [Figure 8] This is an unfolded view showing the inner circumferential surface of the outer annular portion of a non-pneumatic tire according to a third embodiment, and is a diagram for explaining the spacing of the spoke connections that are connected to the inner circumferential surface in the tire's circumferential direction. [Figure 9] This is a cross-sectional view taken along line IX-IX in Figure 8. [Modes for carrying out the invention]

[0010] (First Embodiment) The first embodiment will be described below with reference to the drawings. Figure 1 is a side view of the non-pneumatic tire 1 of the first embodiment, viewed from a direction parallel to the tire rotation axis (tire meridian), that is, along the front-to-back direction of the paper in Figure 1. The non-pneumatic tire 1 shown in Figure 1 is in an unloaded state. Figure 2 is a cross-sectional view taken along line II-II of Figure 1. Figure 3 is a partial perspective view of the non-pneumatic tire 1, viewed from an oblique angle from the portion shown in Figure 2.

[0011] In Figures 1 and 3, arrow D indicates the circumferential direction of the tire. In Figures 1 to 3, arrow X indicates the radial direction of the tire. In Figures 2 and 3, arrow Y indicates the width direction of the tire. In Figure 1, the tire width direction Y is the front-to-back direction of the paper. In Figure 2, the symbol S1 is the tire equatorial plane. In Figure 2, the tire circumferential direction D is the front-to-back direction of the paper.

[0012] The tire circumferential direction D is the direction around the tire rotation axis and is the same direction in which the non-pneumatic tire 1 rotates. The tire radial direction X is the direction perpendicular to the tire rotation axis. The tire width direction Y is the direction parallel to the tire rotation axis. In Figures 2 and 3, one side of the tire width direction Y is shown as Y1 and the other side of the tire width direction Y is shown as Y2. The tire equatorial plane S1 shown in Figure 2 is a plane perpendicular to the tire rotation axis and located at the center of the tire width direction Y. The same applies to the directions indicated by these symbols in Figures 4 to 9.

[0013] The non-pneumatic tire 1 of the first embodiment comprises an inner annular portion 20, an outer annular portion 30, a plurality of spokes 40, and a tread 50. In the following, the thickness of the inner annular portion 20 and the outer annular portion 30 refers to the dimension in the direction along the tire radial direction X. The width of the inner annular portion 20 and the outer annular portion 30 refers to the dimension in the direction along the tire width direction Y as shown in Figure 2.

[0014] The inner annular portion 20 is an annular portion along the tire circumferential direction D that constitutes the inner peripheral portion of the non-pneumatic tire 1. The thickness and width of the inner annular portion 20 are set to be constant in order to improve uniformity. A tire wheel (not shown) is disposed in the space on the inner peripheral side of the inner annular portion 20. The inner peripheral portion of the inner annular portion 20 is fitted and attached to the outer peripheral portion of the rim of the tire wheel. When the inner annular portion 20 is attached to the rim, the non-pneumatic tire 1 is attached to the tire wheel. On the inner peripheral surface of the inner annular portion 20, fitting portions formed by convex portions, grooves, or the like may be provided for fitting with the rim. The inner annular portion 20 can be formed 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 weight reduction and durability while satisfying the function of sufficiently transmitting the rotational force to the spokes 40. The thickness of the inner annular portion 20 is not particularly limited, but for example, it is preferably 2% or more and 7% or less of the tire section height H shown in FIG. 2, and more preferably 3% or more and 6% or less.

[0016] The inner diameter of the inner annular portion 20 is determined according to the dimensions of the rim of the tire wheel to which the non-pneumatic tire 1 is attached, the use of the vehicle, and the like. For example, when assuming replacement of a general pneumatic tire, the inner diameter of the inner annular portion 20 may be, for example, dimensions such as 250 mm or more and 500 mm or less, but is not limited thereto.

[0017] The width of the inner annular portion 20 is appropriately determined according to the use of the vehicle to which the non-pneumatic tire 1 is attached and the like. For example, when assuming replacement of a general pneumatic tire, the width of the inner annular portion 20 may be dimensions such as 100 mm or more and 300 mm or less, but is not limited thereto.

[0018] The outer annular portion 30 is an annular part along the tire circumferential direction D that constitutes the outer circumference of the non-pneumatic tire 1. The outer annular portion 30 is located on the outer circumference side of the inner annular portion 20 and is arranged coaxially with the inner annular portion 20. The thickness and width of the outer annular portion 30 are set to be constant in order to improve uniformity. The outer annular portion 30 can be formed from, 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 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 weight reduction and durability while satisfying 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 for example, it is preferably 2% to 7% of the tire cross-sectional height H shown in Figure 2, and more preferably 2% to 5%.

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

[0021] The width of the outer annular portion 30 is determined appropriately according to the intended use of the vehicle on which the non-pneumatic tire 1 is fitted. For example, when considering a replacement for a general pneumatic tire, the width of the outer annular portion 30 may be between 100 mm and 300 mm, but is not limited to this.

[0022] Multiple 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 multiple spokes 40, are arranged coaxially with respect to each other. Each of the multiple spokes 40 is arranged independently along the tire circumferential direction D. As shown in Figure 1, when the non-pneumatic tire 1 is unloaded, the multiple spokes 40 extend linearly in the radial direction, approximately parallel to the tire radial direction X, when viewed from the side.

[0023] As shown in Figures 2 and 3, the spokes 40 of the first embodiment include a plurality of first spokes 41 and a plurality of second spokes 42. The extending direction of both the first spokes 41 and the second spokes 42 is not parallel to the tire radial direction X when viewed along the tire circumferential direction D. 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 from the first spokes 41. The first spokes 41 and the second spokes 42 are arranged alternately in the tire circumferential direction D.

[0024] More specifically, as shown in Figures 2 and 3, the first spoke 41 extends inclined from the Y1 side, which is one side of the outer annular portion 30 in the tire width direction Y, toward the Y2 side, which is the other side of the inner annular portion 20 in the tire width direction Y. The second spoke 42 extends inclined from the Y2 side, which is the other side of the outer annular portion 30 in the tire width direction Y, toward the Y1 side, which is one side of the inner annular portion 20 in the tire width direction Y.

[0025] The inclination angles of the first spoke 41 and the second spoke 42 are the same. Therefore, when viewed from a direction along the tire circumferential direction D, the first spoke 41 and the second spoke 42 adjacent to each other in the tire circumferential direction D are arranged in a roughly X shape. As shown in Figure 2, the first spoke 41 and the second spoke 42 are inclined at an angle θ with respect to the width direction Y, and this angle θ is preferably, for example, 30° to 60°.

[0026] As shown in Figure 2, when viewed from a direction along the tire circumferential direction D, the first spoke 41 and the second spoke 42 each have the same shape, symmetrical with respect to the tire equatorial plane S1. Therefore, in the following, there is no need to distinguish between the first spoke 41 and the second spoke 42, and when they can be described together, the first spoke 41 and the second spoke 42 will be collectively referred to as spoke 40.

[0027] The spokes 40 are plate-shaped and extend diagonally from the inner annular portion 20 toward the outer annular portion 30 at an angle θ as described above. As shown in Figure 3, the plate thickness t of the spokes 40 along the tire circumferential direction is smaller than the plate width w, and the direction of the plate thickness t is along the tire circumferential direction D. That is, the spokes 40 are formed in a plate shape that extends along the plane of the tire radial direction X and the tire width direction Y. The plate width w referred to here is the dimension in the direction perpendicular to the inclination direction on which the spokes 40 extend, when the spokes 40 are viewed from a direction along the tire circumferential direction D, as also shown in Figure 2. In the first embodiment, the plate thickness t of all spokes 40 is the same. Also, the plate width w of all spokes 40 is the same.

[0028] Since the spokes 40 are long, plate-shaped, even if the plate thickness t is reduced, the durability of the spokes 40 can be improved by setting a wider plate width w. Furthermore, by reducing the plate thickness t and increasing the number of spokes 40, the spacing between adjacent spokes 40 in the tire circumferential direction D can be reduced while maintaining the overall rigidity of the non-pneumatic tire 1. This distributes the contact pressure during tire rolling by the spokes 40, thereby reducing the contact pressure. In the first embodiment, the spokes 40 are parallel to the tire radial direction X in a side view, but the spokes 40 may be arranged diagonally with respect to the tire radial direction X so as to intersect with the tire radial direction X in a side view.

[0029] As shown in Figures 2 and 3, the first spoke 41 has a first inner connecting portion 411 that connects to the inner annular portion 20 on the tire width direction Y2 side, and a first outer connecting portion 412 that connects to the outer annular portion 30 on the tire width direction Y1 side. The second spoke 42 has a second inner connecting portion 421 that connects to the inner annular portion 20 on the tire width direction Y1 side, and a second outer connecting portion 422 that connects to the outer annular portion 30 on the tire width direction Y2 side. The first outer connecting portion 412 and the second outer connecting portion 422 are examples of connecting portions.

[0030] As shown in Figure 2, the first inner connecting portion 411 of the first spoke 41 has a shape that widens along the tire width direction Y as it approaches the inner annular portion 20. The side surface 411a of the first inner connecting portion 411 on the tire width direction Y2 side extends in a gentle curve to the end 20b of the inner annular portion 20 on the tire width direction Y2 side. The side surface 411b of the first inner connecting portion 411 on the tire width direction Y1 side extends in a curve toward the tire width direction Y1 to the position of the tire equatorial plane S1 of the inner annular portion 20.

[0031] The first outer connecting portion 412 of the first spoke 41 has the same shape as the first inner connecting portion 411, and has a shape that widens along the tire width direction as it approaches the outer annular portion 30. The side surface 412a of the first outer connecting portion 412 on the tire width direction Y1 side extends in a gentle curve to the end 30a of the outer annular portion 30 on the tire width direction Y1 side. The side surface 412b of the first outer connecting portion 412 on the tire width direction Y2 side extends in a curve toward the tire width direction Y2 to the position of the tire equatorial plane S1 of the outer annular portion 30. The first inner connecting portion 411 is provided in half of the inner annular portion 20 on the tire width direction Y2 side. The first outer connecting portion 412 is provided in half of the outer annular portion 30 on the tire width direction Y1 side.

[0032] As shown in Figure 2, the second inner connecting portion 421 of the second spoke 42 has a shape that widens along the tire width direction Y as it approaches the inner annular portion 20. The side surface 421a of the second inner connecting portion 421 on the tire width direction Y1 side extends in a gentle curve to the end 20a of the inner annular portion 20 on the tire width direction Y1 side. The side surface 421b of the second inner connecting portion 421 on the tire width direction Y2 side extends in a curve toward the tire width direction Y2 to the position of the tire equatorial plane S1 of the inner annular portion 20.

[0033] The second outer connecting portion 422 of the second spoke 42 has the same shape as the second inner connecting portion 421, and has a shape that widens along the tire width direction as it approaches the outer annular portion 30. The side surface 422a of the second outer connecting portion 422 on the tire width direction Y2 side extends in a gentle curve to the end 30b of the outer annular portion 30 on the tire width direction Y2 side. The side surface 422b of the second outer connecting portion 422 on the tire width direction Y1 side extends in a curve toward the tire width direction Y1 to the position of the tire equatorial plane S1 of the outer annular portion 30. The second inner connecting portion 421 is provided in half of the inner annular portion 20 on the tire width direction Y1 side. The second outer connecting portion 422 is provided in half of the outer annular portion 30 on the tire width direction Y2 side.

[0034] As described above, the plate thickness t of all spokes 40 in the first embodiment is the same. The dimension of the plate thickness t is not particularly limited, but in order for the spokes 40 to receive sufficient rotational force from the inner annular portion 20 and the outer annular portion 30, and to be able to deform appropriately when subjected to a load, it is preferably 1 mm to 30 mm, and more preferably 5 mm to 25 mm.

[0035] As described above, the plate width w of all spokes 40 in the first embodiment is the same. The plate width w of the spokes 40 is not particularly limited, but it is preferably 5 mm to 25 mm, and more preferably 10 mm to 20 mm, in order to sufficiently receive rotational force from the inner annular portion 20 and the outer annular portion 30, while also allowing for appropriate deflection and deformation when a load is applied. Furthermore, the plate width w is preferably 110% or more of the plate thickness t, and more preferably 115% or more, from the viewpoint of improving durability while distributing the ground pressure.

[0036] The number of spokes 40 is preferably 80 to 300, and more preferably 100 to 200, from the viewpoint of being able to sufficiently support the load from the vehicle, reduce weight, and improve both power transmission and durability.

[0037] The spokes 40 can be formed from the elastic materials listed below. First, regarding the properties of the elastic material, from the viewpoint of providing appropriate rigidity while ensuring sufficient durability, it is preferable that the tensile modulus calculated from the tensile stress at 10% elongation, as determined by a tensile test conducted in accordance with JIS K7312:1996, is between 3 MPa and 12 MPa.

[0038] If the tensile modulus calculated from the tensile stress at 10% elongation in spoke 40 is less than 3 MPa, sufficient rigidity cannot be obtained, and adjacent spokes 40 in the tire circumferential direction D 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 of ride comfort.

[0039] Elastic materials used as the base material for spoke 40 include thermoplastic elastomers, cross-linked rubber, and other resins.

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

[0041] The rubber material used to make up the crosslinked rubber can be either natural rubber or synthetic rubber. Examples of synthetic rubbers 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. Examples of thermoplastic resins include polyethylene resin, polystyrene resin, and polyvinyl chloride resin. Examples of thermosetting resins include epoxy resin, phenolic resin, polyurethane resin, silicone resin, polyimide resin, and melamine resin.

[0043] From the viewpoint of moldability, processability, and cost, polyurethane resin is preferably used for the spokes 40 among the elastic materials mentioned above. Foamed materials can also be used as the elastic material. That is, foamed thermoplastic elastomers, crosslinked rubbers, and other resins can be used.

[0044] Furthermore, the elastic material used as the base material for 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 types of reinforcing fibers include rayon cord, polyamide cord such as nylon-6,6, polyester cord such as polyethylene terephthalate, aramid cord, glass fiber cord, carbon fiber, and steel cord.

[0045] Furthermore, reinforcement of elastic materials is not limited to reinforcement with reinforcing fibers. For example, reinforcement may be carried out by adding granular fillers. Examples of granular fillers that can be added include carbon black, silica, ceramics such as alumina, and other inorganic fillers.

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

[0047] The tread 50 is provided on the outer circumferential surface of the outer annular portion 30. The tread 50 constitutes the outermost part 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 surface that contacts the road surface. There are no particular restrictions on the type of rubber material used for the tread rubber 51; general vulcanized rubber used for the treads of vehicle tires can be used. The tread surface 51a of the tread rubber 51 is provided with a tread pattern formed by multiple grooves and flat areas, similar to conventional pneumatic tires. The tread rubber 51 may also be composed of multiple layers of rubber with different components and properties (for example, two or three layers). Furthermore, the tread 50 may be made of resin.

[0048] The non-pneumatic tire 1 of the first embodiment further includes a reinforcing layer 55. As shown in Figures 2 and 3, in the first embodiment, the reinforcing layer 55 is embedded in the outer annular portion 30.

[0049] The reinforcing layer 55 is evenly distributed around the entire circumference of the tire to suppress buckling, which occurs when the outer annular portion 30 bends inward (towards the tire rotation axis) in the tire radial direction X at the center of the tire width direction Y. The reinforcing layer 55 is constructed, for example, by arranging cords made of steel or fiber-reinforced plastic such as CFRP or GFRP so as to be roughly parallel to the tire width direction Y. In addition, cylindrical metal rings, high-modulus resin rings, etc., may be used as the reinforcing layer 55. Furthermore, the reinforcing layer 55 may be provided embedded in the outer annular portion 30. By providing the reinforcing layer 55, the rigidity of the non-pneumatic tire 1 is ensured, and the contact of the tread 50 with the road surface is improved. The reinforcing layer 55 may be provided as needed, or it may be omitted.

[0050] Figure 4 is an enlarged view of part IV of Figure 1, and is a partial side view of the non-pneumatic tire 1. Figure 5 is an unfolded view showing the inner circumferential surface of the outer annular portion 30 of the non-pneumatic tire 1, schematically showing the state in which the first outer connection portion 412 of the first spoke 41 and the second outer connection portion 422 of the second spoke 42 are connected to this inner circumferential surface.

[0051] As shown in Figures 4 and 5, the non-pneumatic tire 1 of the first embodiment has uneven spacing G between adjacent spokes 40 in the tire circumferential direction D. In the following description, the spacing G between spokes 40 will be referred to as the spoke spacing G. In the first embodiment, the 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, which are adjacent in the tire circumferential direction D. More specifically, as shown in Figure 5, the spoke spacing G is the distance in the tire circumferential direction D between the first outer peripheral end 412c on the side of the second outer connection portion 422 of the boundary between the first outer connection portion 412 and the inner circumferential surface of the outer annular portion 30 of the first outer connection portion 412, and the second outer peripheral end 422c on the side of the first outer connection portion 412 of the boundary between the second outer connection portion 422 and the inner circumferential surface of the outer annular portion 30 of the first outer connection portion 422, which are adjacent in the tire circumferential direction D.

[0052] The spoke spacing G in the first embodiment includes at least three spoke spacings: a first spacing S, a second spacing M that is longer than the first spacing S, and a third spacing L that is longer than the second spacing M. These three spoke spacings G are distributed in the tire circumferential direction D. That is, the spoke spacing G, which represents the gap between the first outer peripheral end 412c of the first outer connecting portion 412 and the second outer peripheral end 422c of the second outer connecting portion 422 adjacent to the tire circumferential direction D, is arranged irregularly in the tire circumferential direction D so that the three spacings S, M, and L are not periodic around the entire circumference of the tire 1. Therefore, in the first embodiment, the pitch of the multiple spokes 40 arranged in the tire circumferential direction D is also non-uniform. Here, pitch refers to the distance between the centers of adjacent spokes 40 in the tire circumferential direction D.

[0053] Furthermore, it is preferable that the spoke spacing G be set to 2 mm or more and 30 mm or less. The spoke spacing G may be, for example, 7 mm for the first spacing S, 9 mm for the second spacing M, and 11 mm for the third spacing L, but is not limited to this. Furthermore, it is preferable that the tensile modulus calculated from the tensile stress when the spoke 40 is elongated by 10% is 3 MPa or more, and that the minimum spoke spacing G is 2.5 mm or more. This makes it possible to suppress situations in which adjacent spokes 40 in the tire circumferential direction D come into contact with each other.

[0054] In the first embodiment, the spoke spacing G may include, for example, an arrangement order in which a first spacing S, a second spacing M located next to the first spacing S and at a different distance from the first spacing S, and a third spacing L located next to the second spacing M and at a different distance from the second spacing M are arranged in that order. The spoke spacing G may also include, for example, an arrangement order in which a first spacing S, a second spacing M located next to the first spacing S and at a different distance from the first spacing S, a third spacing L located next to the second spacing M and at a different distance from the second spacing M, and a fourth spacing K located next to the third spacing L and at a different distance from the third spacing L are arranged in that order. By including such a configuration, the frequency components of pitch noise during tire rolling can be effectively dispersed.

[0055] According to the first embodiment, since the spoke spacing G, which is the distance between adjacent spokes 40 in the circumferential direction D of the tire, is non-uniform, even if the plate thickness t of the spokes 40 is uniform, the pitch of multiple spokes 40 can also be made non-uniform. When the tire is rolling, noise of a frequency corresponding to the position of the outer connection part of the spokes becomes a problem, but according to the first embodiment, with a simple configuration, the frequency of pitch noise when the tire is rolling can be dispersed, and the pitch noise generated by the spokes 40 striking the road surface can be reduced.

[0056] Furthermore, the non-pneumatic tire 1 of the first embodiment has an uneven spoke spacing G, and the tensile modulus calculated from the tensile stress of the spokes 40 when they are elongated by 10% is between 3 MPa and 12 MPa. In addition, the spokes 40 are configured such that the first spokes 41 and the second spokes 42 are arranged in a roughly X shape when viewed from a direction along the tire circumferential direction D. This reduces pitch noise, suppresses the reduction in tire durability, and maintains a good ride comfort.

[0057] The non-pneumatic tire 1 of this embodiment provides the following effects. (1) The non-pneumatic tire 1 according to the first embodiment comprises an inner annular portion 20, an outer annular portion 30 arranged coaxially with the inner annular portion 20 on the outer circumference 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 in the tire circumferential direction D, and a tread 50 provided on the outer circumference surface of the outer annular portion 30, wherein the spoke spacing G, which is the distance between adjacent spokes 40 in the tire circumferential direction D, is non-uniform.

[0058] As a result, the uneven spacing G between spokes causes the spokes 40 to strike the road surface during tire rotation, resulting in discontinuous impact noise and reduced pitch noise.

[0059] (2) In the non-pneumatic tire 1 of the first embodiment, each of the plurality of first spokes 41 has a first outer connecting portion 412 connected to the outer annular portion 30, and each of the plurality of second spokes 42 has a second outer connecting portion 422 connected to the outer annular portion 30, and the spoke spacing G is preferably the distance between adjacent first outer connecting portions 412 and second outer connecting portions 422 in the tire circumferential direction D.

[0060] The road surface impact noise caused by the first spoke 41 and the second spoke 42 is generated by the first outer connecting portion 412 and the second outer connecting portion 422, which are connected to the outer annular portion 30. Therefore, by making the spacing between the first outer connecting portion 412 and the second outer connecting portion 422 uneven, pitch noise can be effectively reduced.

[0061] (3) In the non-pneumatic tire 1 of the first embodiment, the spoke spacing G is preferably such that there are two or more, a first spacing S and a second spacing M which is longer than the first spacing S, and the spokes 40 are arranged so that the first spacing S and the second spacing M are not periodic.

[0062] This effectively creates discontinuities in the road surface impact noise caused by the spokes 40, further reducing pitch noise.

[0063] (4) In the non-pneumatic tire 1 of the first embodiment, it is preferable that the tensile modulus of the spoke 40, calculated from the tensile stress at 10% elongation when a tensile test is performed in accordance with JIS K7312:1996, is 3 MPa or more and 12 MPa or less.

[0064] As a result, the spokes 40 have appropriate rigidity, and the bending of the spokes 40 and contact with adjacent spokes 40 is suppressed, making it less likely for adjacent spokes 40 in the tire circumferential direction D to come into contact with each other. Therefore, the reduction in tire durability due to damage to the spokes 40 can be suppressed.

[0065] (5) In the non-pneumatic tire 1 of the first embodiment, the spokes 40 include a first spoke 41 that is inclined toward one side in the tire axial direction and a second spoke 42 that is inclined toward the opposite side from the first spoke 41, and it is preferable that the first spoke 41 and the second spoke 42 are arranged alternately in the tire circumferential direction D.

[0066] As a result, the first spoke 41 and the second spoke 42 are arranged in a roughly X shape when viewed from a direction along the tire circumferential direction D. Since the first spoke 41 and the second spoke 42 are each inclined in the direction of the tire axis, excessive rigidity is suppressed, and ride comfort is improved.

[0067] Next, the second and third embodiments will be described. The second and third embodiments are variations of the spoke 40 in the first embodiment, and all other configurations are the same as the first embodiment. Therefore, in the following description, components common to both the first and third embodiments are denoted by the same reference numerals and their descriptions are omitted, with the focus being on the differences.

[0068] (Second Embodiment) Figure 6 is a partial side view of a non-pneumatic tire of the second embodiment, and corresponds to Figure 4. Figure 7 is an unfolded view of the inner circumferential surface of the outer annular portion 30 of the non-pneumatic tire of the second embodiment.

[0069] In the second embodiment, in the tire circumferential direction D, there is a long-spoke region E where the spacing between spokes 40 is relatively long, and a short-spoke region F where the spacing between spokes 40 is relatively short. When the same number of spokes 40 are arranged, the long-spoke region E has a longer distance in the tire circumferential direction D than the short-spoke region F. The spokes 40 include long-spoke side spokes 40e1 arranged in the long-spoke region E and short-spoke side spokes 40f1 arranged in the short-spoke region F. The dimension te in the tire circumferential direction D of the long-spoke side spoke 40e1 is greater than the dimension tf in the tire circumferential direction D of the short-spoke side spoke 40f1.

[0070] Specifically, in the second embodiment, in the tire circumferential direction D, there is a long-spacing region E in which at least one spoke 40 is positioned between two spokes 40, and a short-spacing region F in which at least one spoke 40 is also positioned between two spokes 40. The long-spacing region E has a longer distance in the tire circumferential direction D than the short-spacing region F.

[0071] In the second embodiment, two long-spoke side spokes 40e1 are arranged in the long-spoke region E, and two short-spoke side spokes 40f1 are arranged in the short-spoke region F. One of the two long-spoke side spokes 40e1 is the first spoke 41, and the other is the second spoke 42. One of the two short-spoke side spokes 40f1 is the first spoke 41, and the other is the second spoke 42. That is, the spoke 40 includes the long-spoke side spokes 40e1 and the short-spoke side spokes 40f1.

[0072] The thickness (dimension D in the tire circumferential direction) te of the long-spacing spoke 40e1 is greater than the thickness tf of the short-spacing spoke 40f1. In other words, in the second embodiment, the long-spacing region E, where the spacing of the spokes 40 in the tire circumferential direction D is relatively large, is provided with the long-spacing spokes 40e1, which have a relatively thicker plate thickness, and the short-spacing region F, where the spacing of the spokes 40 in the tire circumferential direction D is relatively small, is provided with the short-spacing spokes 40f1, which have a relatively thinner plate thickness.

[0073] For example, regarding the thickness of the spokes 40, the thickness te of the long-spacing spokes 40e1 may be 17 mm, and the thickness tf of the short-spacing spokes 40f1 may be 12 mm, but it is not limited to this, as long as the thickness te of the long-spacing spokes 40e1 is thicker than the thickness tf of the short-spacing spokes 40f1.

[0074] (6) In the second embodiment, in the tire circumferential direction D, there is a long-spacing region E where the spacing between the spokes 40 is relatively long, and a short-spacing region F where the spacing between the spokes 40 is relatively short, and the spokes 40 include long-spacing spokes 40e1 and short-spacing spokes 40f1, wherein in the long-spacing region E, at least one long-spacing spoke 40e1 is positioned between two spokes 40, and in the short-spacing region F, at least one short-spacing spoke 40f1 is positioned between two spokes 40, and the dimension of the long-spacing spoke 40e1 in the tire circumferential direction D is greater than the dimension of the short-spacing spoke 40f1 in the tire circumferential direction D.

[0075] As a result, the long-spoke side spokes 40e1, which have a larger plate thickness, are placed in the long-spoke region E, where tire rigidity tends to be lower, thus suppressing the decrease in tire rigidity in the long-spoke region E. Furthermore, the short-spoke side spokes 40f1, which have a smaller plate thickness, are placed in the short-spoke region F, resulting in uniformity in the tire's circumferential direction D and improved uniformity.

[0076] (Third embodiment) Figure 8 is an unfolded view of the inner circumferential surface of the outer annular portion 30 in the non-pneumatic tire of the third embodiment. Figure 9 is a cross-sectional view taken along line IX-IX of Figure 8. In the third embodiment, similar to the second embodiment, there is a long-spacing region E in the tire circumferential direction D where at least one spoke 40 is positioned between two spokes 40, and a short-spacing region F where at least one spoke 40 is also positioned between two spokes 40.

[0077] In the third embodiment, two long-spoke side spokes 40e2 are arranged in the long-spoke region E, and two short-spoke side spokes 40f2 are arranged in the short-spoke region F. One of the two long-spoke side spokes 40e2 is the first spoke 41, and the other is the second spoke 42. Of the two short-spoke side spokes 40f2, one is the first spoke 41, and the other is the second spoke 42. That is, the spoke 40 includes the long-spoke side spokes 40e2 and the short-spoke side spokes 40f2.

[0078] As shown in Figure 9, the plate width (dimension in the tire circumferential direction D) we of the long-spacing spoke 40e2 is greater than the plate width wf of the short-spacing spoke 40f2. In other words, in the third embodiment, the long-spacing region E, where the spacing of the spokes 40 in the tire circumferential direction D is relatively large, is arranged with the long-spacing spoke 40e2, which has a relatively large plate width, and the short-spacing region F, where the spacing of the spokes 40 in the tire circumferential direction D is relatively small, is arranged with the short-spacing spoke 40f2, which has a relatively small plate width.

[0079] (7) In the third embodiment, in the tire circumferential direction D, there is a long-spacing region E where the spacing between the spokes 40 is relatively long, and a short-spacing region F where the spacing between the spokes 40 is relatively short, and the spokes 40 include long-spacing spokes 40e2 and short-spacing spokes 40f2, wherein in the long-spacing region E, at least one long-spacing spoke 40e2 is positioned between two spokes 40, and in the short-spacing region F, at least one short-spacing spoke 40f2 is positioned between two spokes 40, and the dimension of the long-spacing spoke 40e2 in the tire width direction Y is greater than the dimension of the short-spacing spoke 40f2 in the tire width direction Y.

[0080] As a result, the long-spoke side spokes 40e2, which have a larger plate width, are placed in the long-spoke region E, where tire rigidity tends to be lower, thus suppressing the decrease in tire rigidity in the long-spoke region E. Furthermore, the short-spoke side spokes 40f2, which have a smaller plate width, are placed in the short-spoke region F, resulting in uniformity in the tire circumferential direction D and improved uniformity.

[0081] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and modifications, improvements, etc., made to the extent that the objectives of the present invention can be achieved are also included within the scope of the present invention. For example, the spacing G between spokes adjacent to each other in the circumferential direction D of the tire is not limited to three spacings: a first spacing S, a second spacing M, and a third spacing L. There may be two spacings, or even four or more. The spokes 40 include a first spoke 41 and a second spoke 42 that intersect in a roughly X-shape when viewed from a direction along the tire circumferential direction D, but the spokes 40 are not limited to this and may consist of plate-shaped portions that extend straight in the tire radial direction X. The plate thickness t and plate width w of the spoke 40 do not have to be constant; for example, the plate thickness t may gradually increase or the plate width w may gradually increase as you move from the inner annular portion 20 to the outer annular portion 30. [Explanation of symbols]

[0082] 1. Non-pneumatic tires 20 Inner annular portion 30 Outer annular part 40 spokes 40e1, 40e2 Long-spacing side spokes 40f1, 40f2 Short-spoke side spokes 41 First spoke 42 Second spoke 412 First outer connection part (connection part) 422 External connection part (connection part) 50 tread D Tire circumferential direction E long interval region F short interval region G Spoke spacing Y tire width direction

Claims

1. The inner annular part, The outer annular portion is arranged coaxially on the outer circumference side of the inner annular portion, Multiple spokes are arranged along the circumferential direction of the tire, connecting the inner annular portion and the outer annular portion. A non-pneumatic tire comprising a tread provided on the outer circumferential surface of the outer annular portion, Of the spacings between adjacent spokes in the circumferential direction of the tire, two adjacent spacings are of different sizes. A non-pneumatic tire, wherein the spacing includes an arrangement order in which a first spacing, a second spacing located next to the first spacing and at a different distance from the first spacing, and a third spacing located next to the second spacing and at a different distance from the second spacing are arranged in that order.

2. Each of the multiple spokes has a connecting portion that connects to the outer annular portion, The non-pneumatic tire according to claim 1, wherein the spacing between the spokes is the distance between adjacent connecting portions in the circumferential direction of the tire.

3. The spacing between the spokes includes the first spacing and the second spacing which is longer than the first spacing. The non-pneumatic tire according to claim 1 or 2, wherein the spokes are arranged so that the first interval and the second interval are not periodic.

4. A non-pneumatic tire according to any one of claims 1 to 3, wherein the tensile modulus of the spoke, calculated from the tensile stress at 10% elongation when a tensile test is performed in accordance with JIS K7312:1996, is 3 MPa or more and 12 MPa or less.

5. In the circumferential direction of the tire, there are regions where the spacing between spokes is relatively long, and regions where the spacing between spokes is relatively short. The spokes include long-spoke side spokes and short-spoke side spokes, In the aforementioned long-spacing region, at least one of the long-spacing side spokes is positioned between the two spokes. In the aforementioned short-spacing region, at least one of the short-spacing side spokes is positioned between the two spokes. The non-pneumatic tire according to any one of claims 1 to 4, wherein the circumferential dimension of the long-spoke side is greater than the circumferential dimension of the short-spoke side.

6. In the circumferential direction of the tire, there are regions where the spacing between spokes is relatively long, and regions where the spacing between spokes is relatively short. The spokes include long-spoke side spokes and short-spoke side spokes, The aforementioned long-spacing region is such that at least one of the long-spacing spokes is positioned between the two spokes. The short-spacing region is such that at least one of the short-spacing side spokes is positioned between the two spokes. The non-pneumatic tire according to any one of claims 1 to 4, wherein the dimension of the long-spoke side in the tire width direction is greater than the dimension of the short-spoke side in the tire width direction.

7. The aforementioned spokes are A first spoke that is inclined to one side in the direction of the tire axis, It includes a second spoke that is inclined to the opposite side from the first spoke, The non-pneumatic tire according to any one of claims 1 to 6, wherein the first spoke and the second spoke are arranged alternately in the circumferential direction of the tire.

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