JP7780313B2 - Non-pneumatic tires - Google Patents

Description

The present invention relates to a non-pneumatic tire.

In recent years, non-pneumatic tires have been developed that eliminate problems like 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 multiple spokes. The multiple spokes are arranged radially and spaced apart around the tire's circumference. A tread that comes into contact with the road surface is provided on the outer peripheral surface of the outer annular portion.

For example, Patent Document 1 discloses a non-pneumatic tire that can improve ride comfort by providing reinforcing parts to the spokes and appropriately setting the area of the reinforcing parts.

Japanese Patent Application Laid-Open No. 2019-43505

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 described in Patent Document 1 above can improve ride comfort, it does not take into consideration pitch noise while the tire is running.

The object of the present invention is to provide a non-pneumatic tire that can reduce pitch noise.

The non-pneumatic tire of the present invention comprises 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.

The present invention provides a non-pneumatic tire that can reduce pitch noise.

1 is a side view showing a non-pneumatic tire according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 3 is a partial perspective view of a non-pneumatic tire, as seen obliquely from the portion shown in FIG. 2. [0023] FIG. FIG. 2 is a development view schematically showing division of pitch elements in a tread pattern. FIG. 2 is an enlarged view of a V portion of FIG. 1 and a partial side view of a non-pneumatic tire. 5 is a perspective view of the positions of the spoke connections in comparison with the developed view of FIG. 4. FIG. FIG. 7 is a diagram corresponding to FIG. 6 and shows a modified example of the first and second arrangement patterns.

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., 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.

In Figures 1 and 3, arrow C indicates the tire circumferential direction. In Figures 1 to 3, arrow X indicates the tire radial direction. In Figures 2 and 3, arrow Y indicates the tire width direction. The tire width direction Y in Figure 1 is the front-to-back direction on the page. In Figure 2, the symbol E indicates the tire equatorial plane. The tire circumferential direction C in Figure 2 is the front-to-back direction on the page.

The tire circumferential direction C is a direction around the tire rotation axis and is the same direction as the rotation direction of the non-pneumatic tire 1. The tire radial direction X is a direction perpendicular to the tire rotation axis. The tire width direction Y is a direction parallel to the tire rotation axis. In Figures 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 Figure 2 is a plane perpendicular to the tire rotation axis and located at the center of the tire width direction Y.
The directions indicated by these symbols are the same in FIGS.

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.

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.

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 lightweight and durability while fully transmitting rotational force to the spokes 40. There are no particular restrictions on the thickness of the inner annular portion 20, but it is preferably 2% to 7% of the tire cross-sectional height H shown in Figure 2, and more preferably 3% to 6%.

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 intended use of the vehicle, etc. For example, when considering a replacement for a general pneumatic tire, the inner diameter of the inner annular portion 20 may be, but is not limited to, a dimension of 250 mm or more and 500 mm or less.

The width of the inner annular portion 20 is determined appropriately depending on the intended use of the vehicle on which the non-pneumatic tire 1 is mounted. For example, when considering 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.

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.

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 lightweight and durability while fully transmitting rotational force from the spokes 40 to the road surface. There are no particular restrictions on the thickness of the outer annular portion 30, but it is preferably 2% to 7% of the tire cross-sectional height H shown in Figure 2, and more preferably 2% to 5%.

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 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, but is not limited to, a dimension of 420 mm or more and 750 mm or less.

The width of the outer annular portion 30 is determined appropriately depending on the intended use of the vehicle on which the non-pneumatic tire 1 is mounted. For example, when considering 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.

The 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 each other. Each of the multiple spokes 40 is 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 multiple spokes 40 extend linearly in the radial direction, approximately parallel to the tire radial direction X, in a side view.

As shown in Figures 2 and 3, the multiple spokes 40 in 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 the tire circumferential direction C. The first spokes 41 are inclined toward one side of 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 C.

More specifically, as shown in Figures 2 and 3, the first spoke 41 extends at an angle 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 at an angle 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.

The inclination angle of the first spoke 41 and the second spoke 42 is the same. Therefore, the first spoke 41 and the second spoke 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 spoke 41 and the second spoke 42 are inclined at an angle θ with respect to the tire width direction Y, and the angle θ is preferably, for example, between 30° and 60°.

As shown in Figure 2, the first spoke 41 and the second spoke 42, when viewed in a direction along the tire circumferential direction C, 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 spoke 41 and the second spoke 42 and they can be described together, the first spoke 41 and the second spoke 42 will be collectively referred to as spoke 40.

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 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. In other words, the spokes 40 are formed in a plate shape extending in the tire radial direction X and tire width direction Y. Note that the width w here refers to the dimension in the direction perpendicular to the inclined direction in which the spokes 40 extend when viewed from the tire circumferential direction C, as also shown in FIG. 2. In this embodiment, all spokes 40 have the same thickness t. All spokes 40 also have the same width w.

Because the spokes 40 are long and plate-shaped, even if the plate thickness t is thin, the durability of the spokes 40 can be improved by setting the plate width w wide. 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 when the tire rolls through the spokes 40, 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.

2 and 3, the first spoke 41 has a first inner connection portion 411 that connects to the tire width direction Y2 side of the inner annular portion 20, and a first outer connection portion 412 that connects to the tire width direction Y1 side of the outer annular portion 30. The second spoke 42 has a second inner connection portion 421 that connects to the tire width direction Y1 side of the inner annular portion 20, and a second outer connection portion 422 that connects 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 that connects to the outer annular portion 30 in this embodiment.

As shown in FIG. 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. The side surface 411a of the first inner connection portion 411 on the tire width direction Y2 side extends in a gently curved manner to the end portion 20b of the inner annular portion 20 on the tire width direction Y2 side. The side surface 411b of the first inner connection portion 411 on the tire width direction Y1 side extends in a curved manner toward the tire width direction Y1 side to the position of the tire equatorial plane E of the inner annular portion 20.

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 the 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 of the inner annular portion 20 on the tire width direction Y2 side. The first outer connecting portion 412 is provided in a half region of the outer annular portion 30 on the tire width direction Y1 side.

As shown in FIG. 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. The side surface 421a of the second inner connection portion 421 on the tire width direction Y1 side extends in a gently curved manner to the end portion 20a of the inner annular portion 20 on the tire width direction Y1 side. The side surface 421b of the second inner connection portion 421 on the tire width direction Y2 side extends in a curved manner toward the tire width direction Y2 side to the position of the tire equatorial plane E of the inner annular portion 20.

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 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 of the inner annular portion 20 on the tire width direction Y1 side. The second outer connecting portion 422 is provided in a half region of the outer annular portion 30 on the tire width direction Y2 side.

As mentioned above, all spokes 40 in this embodiment have the same thickness t. While there are no particular limitations on the thickness t, it is preferable that the thickness t be between 1 mm and 30 mm, and more preferably between 5 mm and 25 mm, so that the spokes 40 can adequately withstand rotational forces from the inner annular portion 20 and the outer annular portion 30 while still being able to flex appropriately when subjected to a load.

As mentioned above, in this embodiment, all spokes 40 have the same width w. There are no particular limitations on the width w of the spokes 40, but in order to be able to adequately withstand rotational forces from the inner annular portion 20 and the outer annular portion 30 while also being able to flex appropriately when subjected to a load, it is preferable that the width w be 5 mm or more and 25 mm or less, and more preferably 10 mm or more and 20 mm or less. Furthermore, from the perspective of being able to distribute ground pressure while improving durability, the width w is preferably 110% or more of the thickness t, and more preferably 115% or more.

The number of spokes 40 is preferably between 80 and 300, and more preferably between 100 and 200, from the perspective of being able to adequately support the load from the vehicle while also being lightweight and improving both power transmission and durability.

The spokes 40 can be made from the elastic materials listed below. First, in terms of the characteristics of the elastic material, in order to ensure adequate durability while providing appropriate rigidity, 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.

If the tensile modulus of a spoke 40 calculated from the tensile stress at 10% elongation is less than 3 MPa, sufficient rigidity will not be obtained, and there is a possibility that adjacent spokes 40 in the tire circumferential direction C will 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 will be excessively high, resulting in a poor ride.

Elastic materials that can be used as the base material for the spokes 40 include thermoplastic elastomers, cross-linked rubber, and other resins.

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

The rubber material that makes up the cross-linked rubber can be either natural 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.

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

Of the above elastic materials, polyurethane resin is preferably used for the spokes 40 from the standpoints of moldability, processability, and cost. However, foamed materials can also be used as the elastic material. That is, foamed materials made from the above-mentioned thermoplastic elastomers, cross-linked rubber, and other resins can be used.

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 fiber cords, and steel cords.

Note that the reinforcement of the elastic material is not limited to reinforcement with reinforcing fibers. For example, reinforcement may be achieved by adding granular fillers. Examples of granular fillers that can be added include ceramics such as carbon black, silica, and alumina, as well as fillers made of other inorganic materials.

The inner annular portion 20 and outer annular portion 30 are preferably formed from the same resin material as the spokes 40. In this case, the inner annular portion 20, outer annular portion 30, and spokes 40 can be integrally molded, for example, by a cast molding method.

The tread 50 is provided on the outer peripheral surface of the outer annular portion 30 .
The tread 50 constitutes 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 constituting the tread of vehicle tires, 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 laminated structure (for example, two or three layers) of rubber layers with different components or characteristics. The tread 50 may also be made of resin.

The non-pneumatic tire 1 of this 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.

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 of 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.

Figure 4 is a development diagram that schematically shows the division of pitch elements in the tread pattern of tread 50. In Figure 4, the vertical direction on the paper surface is the tire circumferential direction C, and the horizontal direction on the paper surface is the tire width direction Y. Figure 4 corresponds to a view of a portion of the outer surface of tread 50 in the V-section region of Figure 1, for example, as seen from the outer periphery of the tire.

The tread 50 has a tread pattern in which multiple pitch elements (pattern constituent units) with different pitch lengths P1 are arranged in a first arrangement pattern along the tire circumferential direction C.

The first arrangement pattern of this embodiment is a pattern in which patterns TS, TM, and TL serving as multiple pitch elements are arranged at a so-called variable pitch. Here, variable pitch means that the pitch elements that are used repeatedly are arranged with different pitch lengths P1. Note that the pitch length P1 in the first arrangement pattern is determined by the circumferential length of the patterns TS, TM, and TL serving 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.

The first arrangement pattern of this embodiment includes multiple 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 different lengths: 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 dispersedly 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.

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

Figure 5 is an enlarged view of the V section of Figure 1, and a partial side view of a non-pneumatic tire. Figure 6 is a perspective view of the connection points of the spokes 40 connected to the inner circumferential surface of the outer annular portion 30, as compared to the developed view that schematically shows the tread pattern of Figure 4. That is, Figure 6 is a diagram showing the relationship between the first and second arrangement patterns, and shows the virtual positions of the connection points of the spokes 40 projected onto the surface of the tread pattern with dashed lines.

The multiple spokes 40 are arranged along the tire circumferential direction C at a pitch that is offset 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 offset from the first arrangement pattern of the tread pattern.

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 portion 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.

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 of the connection portions of adjacent spokes 40 in the tire circumferential direction C. In other words, when the distance between the connection portions of two spokes 40 adjacent 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 corresponding to the thickness t of the connection portion of one spoke 40 adjacent to the inter-spoke spacing G, and half the length corresponding to the thickness t of the connection portion of the other spoke 40 adjacent to the inter-spoke spacing G.

The connection portions of the multiple spokes 40 are arranged at a variable pitch having multiple pitch lengths P2 that deviate from the variable pitch of the tread pattern. It is preferable that 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 deviate from the variable pitch of the tread pattern.

The second arrangement pattern of this embodiment has at least three different 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 in the tire circumferential direction C. In this embodiment, as shown in FIG. 5, the pitch lengths P2 are arranged in the order 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.

The second arrangement pattern of this embodiment includes an arrangement order in which a first pitch, a second pitch that is arranged adjacent to the first pitch and has a pitch length different from the first pitch, and a third pitch that is arranged adjacent to the second pitch and has 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 pitch length S2, a second pitch that is arranged adjacent to the first pitch and has a pitch length M2 that is different from pitch length S2, and a third pitch that is arranged adjacent to the second pitch and has a pitch length L2 that is different from pitch length M2, are arranged. The second arrangement pattern may include an arrangement sequence that includes 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. In this case, the pitch lengths of non-adjacent pitches, such as the second pitch and the fourth pitch, may be the same. This configuration effectively disperses the frequency components of pitch noise during tire rotation. During tire rotation, noise with frequencies depending on the position of the outer spoke connection points can be problematic. However, this embodiment disperses the pitch noise frequency during tire rotation, thereby reducing pitch noise generated when the spokes 40 strike the road surface.

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

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. In the following description, the spacing G between the spokes 40 is referred to as the inter-spoke spacing G. In this embodiment, the inter-spoke spacing G refers to 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 C. More specifically, as shown in FIG. 5 , the inter-spoke spacing G refers to the distance in the tire circumferential direction C between the first outer end 412c 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 the second outer end 422c 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, for the first spoke 41 and the second spoke 42, which are adjacent in the tire circumferential direction C.

In this embodiment, the spoke spacing G includes at least three types: spacing S, spacing M longer than spacing S, and spacing L longer than spacing M. These three types of spoke spacing G are distributed in the tire circumferential direction C. In other words, the 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 irregularly arranged in the tire circumferential direction C so 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.

The spoke spacing G is preferably set to a value between 2 mm and 30 mm. For example, the spoke spacing G may be, but is not limited to, 7 mm for spacing S, 9 mm for spacing M, and 11 mm for spacing L. 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 prevents contact between adjacent spokes 40 in the tire circumferential direction C. As a result, a reduction in tire durability due to spoke damage can be prevented.

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 spacing S, spacing M adjacent to spacing S and a different distance from spacing S, and 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. This configuration effectively disperses the frequency components of pitch noise during tire rotation.

It is preferable that the arrangement order of the pitch lengths P1 of the multiple pitch elements defined by the first arrangement pattern differs 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 differs.

Note that if the pitch based on the angle relative to the tire rotation axis is expressed as angular pitch, the connection portions 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.

In this embodiment, the tread 50 has a tread pattern in which multiple pitch elements with different pitch lengths P1 are arranged in a first arrangement pattern along the tire circumferential direction C. The multiple spokes 40 are arranged along the tire circumferential direction at a pitch that is offset 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.

Figure 7 corresponds to Figure 6 and illustrates a specific example of this embodiment, showing a modified example of the arrangement of the first and second arrangement patterns. 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 multiple grooves, including a center main groove 52A, center lateral grooves 52B, shoulder main grooves 52C, shoulder lateral grooves 52D, and narrow grooves 52E.

The first arrangement pattern of this modified example is a pattern in which multiple pitch element patterns TSA, TSB, TMA, TMB, TLA, and TLB are arranged at a so-called variable pitch.

Specifically, the first arrangement pattern of this modified example includes pitch elements TSA and TSB with a pitch length S1, pitch elements TMA and TMB with a pitch length M1 longer than pitch length S1, and pitch elements TLA and TLB with a pitch length L1 longer than pitch length M1. These multiple pitch elements with different pitch lengths are dispersed 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 circumference, or may be arranged repeatedly.

In this modified example, the connection points of the multiple spokes 40 are arranged at a variable pitch with multiple pitch lengths that deviate from the variable pitch of the tread pattern.

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 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 with a pitch length 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 also shows S3, S3, M3, M3, L3, L3 as the 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.

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.

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 considered as a single pitch element. 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 considered as a single pitch element. Even in this case, the tread 50 has a tread pattern in which multiple pitch elements with different pitch lengths P1 are arranged in the first arrangement pattern along the tire circumferential direction C, and the multiple spokes 40 are arranged at a variable pitch along the tire circumferential direction, offset from the first arrangement pattern.

As described above, in this modified example, the tread 50 also has a tread pattern in which multiple pitch elements with different pitch lengths are arranged in a first arrangement pattern along the tire circumferential direction C. The multiple spokes 40 are then arranged along the tire circumferential direction at a pitch that is offset 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.

The non-pneumatic tire 1 of this embodiment provides the following advantages:

(1) The non-pneumatic tire 1 according to this embodiment comprises 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 in a first arrangement pattern along the tire circumferential direction, and the plurality of spokes 40 are arranged along the tire circumferential direction at a pitch that is offset from the first arrangement pattern.

This reduces pitch noise.

(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 with a pitch offset from the first arrangement pattern, with different pitch lengths P2 along the tire circumferential direction.

This allows for even greater reduction in pitch noise.

(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 this order.

This disperses the frequency of pitch noise when the tire rolls, further reducing pitch noise caused by the spokes 40 striking the road surface.

(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 offset from the variable pitch of the tread pattern.

This allows for even greater reduction in pitch noise.

(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 differs from the arrangement order of the pitch lengths P2 of the connection portions of the multiple spokes 40 defined by the second arrangement pattern.

This allows for even greater reduction in pitch noise.

(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 inter-spoke spacing G, which is the distance between adjacent connection portions in the tire circumferential direction.

This makes it easy to arrange the connections of multiple spokes 40 with different pitch lengths around the tire, even if the thickness of the spokes 40 is constant.

(7) In the non-pneumatic tire 1 of this embodiment, the spokes 40 include first spokes 41 that are inclined to one side in the tire axial direction and second spokes 42 that are inclined to 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, and the pitch length P2 of the connection points of the multiple spokes 40 is determined based on the position of the connection point of the first spoke 41 and the position of the connection point of the second spoke 42 adjacent to the connection point of the first spoke 41.

As a result, 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 C. Because the first spokes 41 and the second spokes 42 are each inclined toward the tire axial direction, excessive rigidity is prevented, improving ride comfort.

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 coming into contact with each other, further maintaining a comfortable ride.

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, i.e., pitch length S1, pitch length M1, and pitch length L1, but may be set to at least two types of pitch lengths, or may be set to four or more types. The pitch length P2 of the second arrangement pattern is not limited to three types, i.e., pitch length S2, pitch length M2, and pitch length L2, but may be set to at least two types of pitch lengths, or may be set to four or more types.
That is, it is preferable that the first arrangement pattern 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 that the first pitch element and the second pitch element are arranged so as not to be periodic. It is also preferable that the pitch length of the second arrangement pattern includes at least the first pitch length and a second pitch length longer than the first pitch length, and that 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 from a direction 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 .

1 Non-pneumatic tire 20 Inner annular portion 30 Outer annular portion 40 Spokes 41 First spoke 42 Second spoke 412 First outer connecting portion (connecting portion)
422 second outer connection part (connection part)
50 Tread C Tire circumferential direction Y Tire width direction

Claims (6)

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. 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. 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. 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. 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. 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.