Cushion tires

Abstract

To provide a cushion tire having excellent durability.SOLUTION: A cushion tire 2 includes: a tread 12 having a tread surface 6 coming in contact with a road surface; a base 14 located on the radial direction inside of the tread 12; a bead 16 embedded in the base 14 and extending in a peripheral direction; and one or two or more reinforcement layers 18 including a plurality of cords 26 parallel to one another and extending in the peripheral direction. The hardness of the base 14 is the same as that of the tread 12 or larger than that of the tread 12. Each of the reinforcement layers 18 extends along at least one side surface 10 and an inner peripheral surface 8 of the tire 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cushion tire, and more particularly to a cushion tire for industrial vehicles such as forklifts. [Background technology]

[0002] Cushion tires (also called solid tires or solid tires) are used on industrial vehicles such as forklifts. These tires are often used under heavy loads. When the vehicle is in use, the tire repeatedly deforms and recovers its shape. In particular, when a large lateral force is repeatedly applied to the tire, the tire may remain deformed and not recover to its original shape. This affects the durability of the tire. A cushion tire with improved durability has been studied and disclosed in JP 2006-82750 A. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-82750 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for cushion tires with improved durability.

[0005] An object of the present invention is to provide a cushion tire that has excellent durability. [Means for solving the problem]

[0006] The present invention relates to a cushion tire whose surface includes an inner circumferential surface and a pair of side surfaces. The cushion tire includes a tread having a tread surface that contacts the road surface, a base located radially inward of the tread, beads embedded in the base and extending in the circumferential direction, and one or more reinforcing layers including a plurality of parallel cords and extending in the circumferential direction. The hardness of the base is the same as or greater than that of the tread. Each reinforcing layer extends along at least one side surface and the inner circumferential surface.

[0007] Preferably, the tire includes a plurality of reinforcing layers. These reinforcing layers are stacked. The cords of each reinforcing layer are inclined with respect to the circumferential direction, and the absolute value of the angle formed by the cords with respect to the circumferential direction is 10° or more and 80° or less. In two adjacent reinforcing layers, the inclination direction of the cords of one reinforcing layer with respect to the circumferential direction is opposite to the inclination direction of the cords of the other reinforcing layer with respect to the circumferential direction.

[0008] Preferably, the tire further includes a rib that protrudes outward and extends in the circumferential direction at the boundary between the tread surface and the side surface. One or more reinforcing layers are present extending along the side surface. When the tire is mounted on a rim, the radial height Hf of the rim flange, the height Ho of the reinforcing layer, and the radial height Hd of the tip of the rib satisfy the following relationship: Hf+(Hd-Hf) / 3≦Ho≦Hd Here, the height Ho represents the height of the radially outer end of the reinforcing layer when the number of reinforcing layers extending along the side surface is one, and represents the height of the radially outer end of the reinforcing layer located closest to the side surface when the number of reinforcing layers extending along the side surface is two or more.

[0009] Preferably, there are multiple reinforcing layers extending along the side surface, and for each pair of adjacent reinforcing layers, the outer end of the reinforcing layer located on the side surface is located radially outward from the outer end of the reinforcing layer located on the inner surface.

[0010] Preferably, for each pair of reinforcing layers, the distance in the radial direction between the outer end of the reinforcing layer located on the side surface side and the outer end of the reinforcing layer located on the inner side is 3.0 mm or more.

[0011] Preferably, when the tire is mounted on a vehicle, the number of reinforcing layers along the side located toward the outside of the vehicle is greater than the number of reinforcing layers along the side located toward the inside of the vehicle.

[0012] Preferably, the cord is made of organic fiber or steel.

[0013] The assembly according to the present invention comprises a rim and a cushion tire mounted on the rim and having an inner circumferential surface and a pair of side surfaces. The cushion tire comprises a tread having a tread surface that contacts the road surface, a base located radially inward of the tread, beads embedded in the base and extending circumferentially, and one or more reinforcing layers including a plurality of parallel cords and extending circumferentially. The hardness of the base is the same as or greater than that of the tread. Each reinforcing layer extends along at least one side surface and the inner circumferential surface. [Effects of the Invention]

[0014] The cushion tire according to the present invention includes a reinforcing layer including a plurality of parallel-arranged cords and extending in the circumferential direction, and beads. The reinforcing layer extends along at least one side surface and the inner circumferential surface. The reinforcing layer and beads effectively suppress tire deformation even when a large lateral force is applied to the tire. This tire achieves excellent durability. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view showing a cushion tire according to one embodiment of the present invention together with a rim. [Figure 2] FIG. 2 is an enlarged, cross-sectional perspective view of a portion of the tire of FIG. [Figure 3] FIG. 3 is a cross-sectional view showing a cushion tire according to another embodiment of the present invention together with a rim. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a portion of FIG. [Figure 5] FIG. 5 is a cross-sectional view showing a cushion tire according to still another embodiment of the present invention together with a rim. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, the present invention will be described in detail based on preferred embodiments, with appropriate reference to the drawings.

[0017] [First embodiment] Fig. 1 is a cross-sectional view showing a cushion tire 2 according to one embodiment of the present invention. In Fig. 1, the up-down direction is the radial direction of the tire 2, the left-right direction is the axial direction of the tire 2, and the direction perpendicular to the plane of the page is the circumferential direction of the tire 2. In Fig. 1, a dashed-dotted line CL represents the equatorial plane of the tire 2. A solid line BL is an imaginary line drawn in the axial direction from the intersection of the equatorial plane CL and the inner surface of the tire 2. This imaginary line BL is called the baseline.

[0018] In FIG. 1, the symbol R indicates a rim. This rim R is a genuine rim. A genuine rim means a rim defined in the standard on which the tire 2 is based. The "standard rim" in the JATMA standard, the "Design Rim" in the TRA standard, and the "Measuring Rim" in the ETRTO standard are all genuine rims.

[0019] In Fig. 1, the tire 2 is mounted on a rim R. A set of the rim R and the cushion tire 2 mounted on the rim R constitutes an assembly 4.

[0020] Of the surfaces of the tire 2, the radially outer surface is called a tread surface 6. The radially inner surface is called an inner circumferential surface 8. The pair of axially outer surfaces are called side surfaces 10. In other words, the surface of the tire 2 includes the tread surface 6, the inner circumferential surface 8, and the pair of side surfaces 10. As shown in FIG. 1 , the tire 2 includes a tread 12, a base 14, beads 16, and a reinforcing layer 18.

[0021] The tread 12 has a shape that is convex outward in the radial direction. The tread 12 forms a tread surface 6 that comes into contact with the road surface. Grooves 20 are cut into the tread surface 6. These grooves 20 form a tread pattern. The side surfaces of the tread 12 form part of the side surfaces 10 of the tire 2. The tread 12 is made of crosslinked rubber that has excellent wear resistance and grip. In this embodiment, the tread 12 is made of a single rubber. The tread 12 may be made of two or more rubbers.

[0022] As shown in FIG. 1, the tread 12 is provided with ribs 22 at the boundaries between the tread surface 6 and each side surface 10. The ribs 22 protrude outward. The ribs 22 extend in the circumferential direction. As shown in FIG. 1, the ribs 22 have a generally trapezoidal shape in this cross section. In FIG. 1, the symbol P indicates the tip of the rib 22. The tip P of the rib 22 is the radially inner vertex of the rib 22 that points outward.

[0023] The base 14 is located radially inward of the tread 12. The base 14 is made of crosslinked rubber. The base 14 does not contain short fibers. The inner circumferential surface of the base 14 contacts the bottom surface 24 of the rim R. The inner circumferential surface of the base 14 forms the inner circumferential surface 8 of the tire 2. The side surface of the base 14 contacts the flange F of the rim R. The side surface of the base 14 forms part of the side surface 10 of the tire 2. In this embodiment, the hardness HDb of the base 14 is greater than the hardness HDt of the tread 12. The hardness HDb of the base 14 may be the same as the hardness HDt of the tread 12.

[0024] In the present invention, the hardness HDb and hardness HDt are measured using a type A durometer in accordance with the provisions of "JIS K6253." The durometer is pressed against the cross section shown in Figure 1 to measure the hardness. The measurement is performed at a temperature of 23°C.

[0025] As shown in FIG. 1, the beads 16 are embedded inside the base 14. In this embodiment, two beads 16 are provided. These beads 16 are provided at positions symmetrical with respect to the equatorial plane CL. Each bead 16 extends in the circumferential direction. The beads 16 are ring-shaped. The beads 16 include a wound non-stretchable wire. A typical material for the wire is steel. The number of beads 16 may be one. Three or more beads 16 may be provided.

[0026] As shown in FIG. 1 , in this cross section, the reinforcing layer 18 extends along both side surfaces 10 and the inner circumferential surface 8. In this specification, the reinforcing layer 18 extending along both side surfaces 10 and the inner circumferential surface 8 is referred to as a "full-width reinforcing layer." Although not shown, the reinforcing layer 18 extends in the circumferential direction while following both side surfaces 10 and the inner circumferential surface 8. On each side surface 10, the radially outer end of the reinforcing layer 18 is located radially outward from the radially outer end of the flange F. The radially outer end of the reinforcing layer 18 is located radially inward from the tip P of the rib 22.

[0027] FIG. 2 is an enlarged cross-sectional perspective view of the tire 2 in FIG. 1 near the inner circumferential surface 8. In FIG. 2, arrow A represents the circumferential direction of the tire 2. The reinforcing layer 18 includes a plurality of cords 26 arranged in parallel. Each cord 26 is inclined with respect to the circumferential direction. In FIG. 2, symbol θ represents the angle that the cord 26 makes with the circumferential direction. The angle θ is measured at the equatorial plane CL. The angle θ is 10° or more and 80° or less. The cords 26 are made of organic fibers. Examples of preferred organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. The material of the cords 26 may be steel.

[0028] The effects of the present invention will be described below.

[0029] The cushion tire 2 according to the present invention includes a reinforcing layer 18 that includes a plurality of parallel-arranged cords 26 and extends in the circumferential direction. The reinforcing layer 18 extends along both side surfaces 10 and the inner circumferential surface 8. The reinforcing layer 18 that extends to both side surfaces 10 effectively suppresses deformation of the tire 2 even when a large lateral force is applied to the tire 2. This tire 2 achieves excellent durability.

[0030] This tire 2 has beads 16. Furthermore, the hardness of the base 14 is equal to or greater than the hardness of the tread 12. By having the beads 16 and the hard base 14 in addition to the reinforcing layer 18, deformation of the tire 2 against forces from many directions is effectively suppressed. This tire 2 achieves excellent durability.

[0031] In this tire 2, deformation is suppressed, and therefore heat generation during use is also effectively suppressed. In this tire 2, damage to the tire 2 due to heat generation is also effectively suppressed. In this tire 2, excellent durability is achieved.

[0032] Cushion tires are used under heavy loads, so when the vehicle starts, stops, accelerates, or decelerates, a phenomenon known as "rim slip" can occur, in which the tire slips against the rim R.

[0033] The reinforcing layer 18 extends along the bottom surface 24. This reinforcing layer 18 improves the force with which the tire 2 clamps the rim R. Furthermore, the bead 16 also improves the force with which the tire 2 clamps the rim R. The reinforcing layer 18 and the bead 16 effectively prevent rim slippage.

[0034] In this tire 2, the reinforcing layer 18, the beads 16, and the hard base 14 contribute to realizing appropriate rigidity of the tire 2. As a result, this tire 2 achieves excellent driving stability.

[0035] In FIG. 1, the double-headed arrow Hf represents the radial height of the outer end of the flange F. The double-headed arrow Ho represents the radial height of the outer end of the reinforcing layer 18. The double-headed arrow Hd represents the radial height of the tip P of the rib 22. The double-headed arrow Hm represents the height calculated as Hf + (Hd - Hf) / 3. All of these heights are measured from the baseline BL.

[0036] The height Ho is preferably equal to or greater than the height Hm. That is, the ratio (Hm / Ho) is preferably equal to or less than 1.0. By setting the height Ho to be equal to or greater than the height Hm, the reinforcing layer 18 effectively suppresses deformation of the tire 2 even when a large lateral force is applied to the tire 2. The tire 2 achieves excellent durability.

[0037] The height Ho is preferably equal to or less than the height Hd. That is, the ratio (Hd / Ho) is preferably equal to or greater than 1.0. In the cushion tire 2, the tread 12 may be worn down to the position of the rib 22 with use. By setting the height Ho to be equal to or less than the height Hd, the cords 26 of the reinforcing layer 18 are prevented from being exposed due to wear. In this tire 2, the rubber is prevented from peeling off from the portions where the cords 26 are exposed. In this tire 2, excellent durability is achieved.

[0038] In this tire 2, the reinforcing layer 18, the hard base 14, and the beads 16 suppress deformation of the tire 2 even though the base 14 does not contain short fibers. Because the base 14 does not contain short fibers, the effect of the base 14 on the vertical rigidity of the tire 2 is suppressed. Excellent ride comfort is achieved in this tire 2. Because the base 14 does not contain short fibers, excellent processability and productivity are achieved.

[0039] As described above, the angle θ formed by the cords 26 of the reinforcing layer 18 with the circumferential direction is equal to or greater than 10° and equal to or less than 80°. In this manner, the reinforcing layer 18 effectively prevents deformation of the tire 2 due to forces from various directions. Excellent durability is achieved in the tire 2. From this viewpoint, the angle θ is more preferably equal to or greater than 15°, and further preferably equal to or greater than 30°. The angle θ is more preferably equal to or less than 75°, and further preferably equal to or less than 60°.

[0040] This tire 2 includes a reinforcing layer 18 including cords 26, and therefore the rigidity of the tire 2 can be easily tuned by changing the angle of the cords 26. This makes it possible to easily realize a tire 2 with performance suited to required driving conditions.

[0041] The hardness HDb of the base 14 is preferably 1.1 times or more the hardness HDt of the tread 12. The base 14 effectively suppresses deformation of the tire 2. Excellent durability is achieved in the tire 2. From this viewpoint, the hardness HDb of the base 14 is more preferably 1.2 times or more the hardness HDt of the tread 12. From the viewpoint of suppressing the influence of the base 14 on the vertical rigidity of the tire 2, the hardness HDb of the base 14 is preferably 1.5 times or less the hardness HDt of the tread 12.

[0042] [Second embodiment] Fig. 3 is a cross-sectional view showing a cushion tire 32 according to another embodiment of the present invention together with a rim R. A set of the rim R and the cushion tire 32 mounted on the rim R constitutes an assembly 34. The tire 32 includes a tread 42, a base 44, beads 46, and a reinforcing layer 36. The tire 32 in Fig. 3 is similar to the tire 2 in Fig. 1 except for the configuration of the reinforcing layer 36.

[0043] As shown in FIG. 3 , the tire 32 includes multiple reinforcing layers 36. In this embodiment, there are four reinforcing layers 36: a first layer 36a, a second layer 36b, a third layer 36c, and a fourth layer 36d, in that order from the outer surface side. These reinforcing layers 36 are stacked. All of these reinforcing layers 36 are full-width reinforcing layers. Although not shown, these reinforcing layers 36 extend in the circumferential direction along both side surfaces 38 and the inner circumferential surface 40. The radially outer end of each reinforcing layer 36 is located radially outward of the radially outer end of the flange F. The radially outer end of each reinforcing layer 36 is located radially inward of the tip P of the rib 48.

[0044] Although not shown, each reinforcing layer 36 includes a plurality of cords arranged in parallel. Each cord is inclined with respect to the circumferential direction. In this embodiment, the absolute value of the angle θ formed by the cord with respect to the circumferential direction for each reinforcing layer 36 is 10° or greater and 80° or less. For two adjacent reinforcing layers 36, the inclination direction of the cords with respect to the circumferential direction in one reinforcing layer 36 is opposite to the inclination direction of the cords with respect to the circumferential direction in the other reinforcing layer 36. That is, the inclination direction of the cords with respect to the circumferential direction in the first layer 36a is opposite to the inclination direction of the cords with respect to the circumferential direction in the second layer 36b. The inclination direction of the cords with respect to the circumferential direction in the second layer 36b is opposite to the inclination direction of the cords with respect to the circumferential direction in the third layer 36c. The inclination direction of the cords with respect to the circumferential direction in the third layer 36c is opposite to the inclination direction of the cords with respect to the circumferential direction in the fourth layer 36d.

[0045] Figure 4 is an enlarged cross-sectional view of the vicinity of one side surface 38 of Figure 3. This view shows the vicinity of the radially outer end of the reinforcing layer 36 along this side surface 38. As shown in Figure 4, four reinforcing layers 36 extend along this side surface 38. In Figure 4, reference numeral E1 represents the radially outer end of the first layer 36a. Reference numeral E2 represents the radially outer end of the second layer 36b. Reference numeral E3 represents the radially outer end of the third layer 36c. Reference numeral E4 represents the radially outer end of the fourth layer 36d.

[0046] The positions of the outer ends of the four reinforcing layers 36 are all different in the radial direction. The closer the reinforcing layer 36 is located to the side surface 38, the more outer its outer end is located in the radial direction. In other words, for each pair of reinforcing layers 36 adjacent to each other along this side surface 38, the outer end of the reinforcing layer 36 located on this side surface 38 is located more outer in the radial direction than the outer end of the reinforcing layer 36 located on the inner side.

[0047] In this tire 32, four reinforcing layers 36 also extend along the other side surface 38. On the other side surface 38, the positions of the outer ends of the four reinforcing layers 36 are all different in the radial direction. The closer the reinforcing layer 36 is located on the side surface 38 side, the more outer its outer end is located in the radial direction. In other words, for each pair of reinforcing layers 36 adjacent to each other along this side surface 38, the outer end of the reinforcing layer 36 located on the side surface 38 side is located more outer in the radial direction than the outer end of the reinforcing layer 36 located on the inner side.

[0048] When the tire 32 includes a plurality of reinforcing layers 36, the number of reinforcing layers 36 does not have to be four. The number of reinforcing layers 36 may be two or three. The number of reinforcing layers 36 may be five or more.

[0049] This cushion tire 32 has a plurality of full-width reinforcing layers. By providing a plurality of full-width reinforcing layers that extend to both side surfaces 38, deformation of the tire 32 is effectively suppressed even when a large lateral force is applied to the tire 32. This tire 32 achieves excellent durability.

[0050] As described above, it is preferable that the radial positions of the outer ends of the multiple reinforcing layers 36 along one side surface 38 are all different. By separating the radial positions of the outer ends of the reinforcing layers 36 from each other, peeling of the rubber at the cord ends of the reinforcing layers 36 is suppressed. This tire 32 achieves excellent durability.

[0051] As described above, for each pair of adjacent reinforcing layers 36 along one side surface 38, it is preferable that the outer end of the reinforcing layer 36 located on this side surface 38 be located radially outward from the outer end of the reinforcing layer 36 located on the inner side. In this way, these reinforcing layers 36 effectively suppress deformation of the tire 32. This tire 32 achieves excellent durability.

[0052] In Figure 4, the double-headed arrow D1 represents the distance between the outer end E1 and the outer end E2 in the radial direction. The double-headed arrow D2 represents the distance between the outer end E2 and the outer end E3 in the radial direction. The double-headed arrow D3 represents the distance between the outer end E3 and the outer end E4 in the radial direction. These distances Di (i = 1, 2, 3) are positive values ​​when the outer end of the reinforcing layer 36 located on the side surface 38 side is located radially outward from the outer end of the reinforcing layer 36 located on the inner side. They are negative values ​​when the outer end of the reinforcing layer 36 located on the side surface 38 side is located radially inward from the outer end of the reinforcing layer 36 located on the inner side.

[0053] For each pair of adjacent reinforcing layers 36 along one side surface 38, the distance Di in the radial direction between the outer end of the reinforcing layer 36 located on the side surface 38 side and the outer end of the reinforcing layer 36 located on the inner side is preferably 3.0 mm or greater. That is, the distances D1, D2, and D3 are all preferably 3.0 mm or greater. This effectively suppresses deformation of the tire 32 while suppressing peeling of the rubber at the cord ends of the reinforcing layers 36.

[0054] As described above, in two adjacent reinforcing layers 36, it is preferable that the inclination direction of the cords in one reinforcing layer 36 relative to the circumferential direction be opposite to the inclination direction of the cords in the other reinforcing layer 36 relative to the circumferential direction. In this way, these reinforcing layers 36 effectively prevent deformation of the tire 32 due to forces from various directions. This tire 32 achieves excellent durability.

[0055] As described above, in each reinforcing layer 36, the absolute value of the angle θ formed by the cord with the circumferential direction is equal to or greater than 10° and equal to or less than 80°. By doing so, these reinforcing layers 36 effectively prevent deformation of the tire 32 due to forces from various directions. Excellent durability is achieved in this tire 32. From this viewpoint, the absolute value of the angle θ is more preferably equal to or greater than 15°, and even more preferably equal to or greater than 30°. The absolute value of the angle θ is more preferably equal to or less than 75°, and even more preferably equal to or less than 60°.

[0056] In FIG. 3, the double-headed arrow Hf represents the radial height of the outer end of the flange F. The double-headed arrow Hd represents the radial height of the tip P of the rib 48. The double-headed arrow Ho represents the radial height of the radially outer end of the reinforcing layer 36. The height Ho is measured at the reinforcing layer 36 located closest to the side surface 38 among the reinforcing layers 36 along this side surface 38. In the embodiment of FIG. 3, the height Ho is measured at the first layer 36a. The double-headed arrow Hm represents the height calculated as Hf + (Hd - Hf) / 3.

[0057] The height Ho is preferably equal to or greater than the height Hm. That is, the ratio (Hm / Ho) is preferably equal to or less than 1.0. By setting the height Ho to be equal to or greater than the height Hm, the reinforcing layer 36 effectively suppresses deformation of the tire 32 even when a large lateral force is applied to the tire 32. The tire 32 achieves excellent durability.

[0058] The height Ho is preferably equal to or less than the height Hd. That is, the ratio (Hd / Ho) is preferably equal to or less than 1.0. By setting the height Ho to be equal to or less than the height Hd, the cords of the reinforcing layer 36 are prevented from being exposed due to wear. In this tire 32, the rubber is prevented from peeling off from the portions where the cords are exposed. In this tire 32, excellent durability is achieved.

[0059] [Third embodiment] 5 is a cross-sectional view showing a cushion tire 52 according to yet another embodiment of the present invention together with a rim R. A set of the rim R and the cushion tire 52 mounted on the rim R constitutes an assembly 54.

[0060] In Figure 5, the direction indicated by arrow X represents the outer side of the vehicle when the tire 52 is mounted on the vehicle. In this specification, the direction indicated by arrow X is referred to as the "front side." The direction indicated by arrow Y represents the inner side of the vehicle when the tire 52 is mounted on the vehicle. In this specification, the direction indicated by arrow Y is referred to as the "back side." The tire 52 includes a tread 56, a base 58, beads 60, and a reinforcing layer 62. The tire 52 is similar to the tire 32 of Figure 3 except for the configuration of the reinforcing layer 62.

[0061] 5, the tire 52 includes a plurality of reinforcing layers 62. In this embodiment, there are four reinforcing layers 62, namely, a first layer 62a, a second layer 62b, a third layer 62c, and a fourth layer 62d, in this order from the outer surface side. These reinforcing layers 62 are stacked one on top of the other.

[0062] 5, the first layer 62a and the second layer 62b are full-width reinforcing layers that extend in the circumferential direction along both side surfaces 64 and the inner circumferential surface 66.

[0063] As shown in FIG. 5, the third layer 62c and the fourth layer 62d both extend along the front side surface 64a and the inner circumferential surface 66. These reinforcing layers 62 do not extend along the back side surface 64b. In this specification, a reinforcing layer 62 that extends along one side surface 64 and the inner circumferential surface 66 but not along the other side surface 64 is referred to as a "short-width reinforcing layer." The third layer 62c and the fourth layer 62d are short-width reinforcing layers. Although not shown, the third layer 62c and the fourth layer 62d extend in the circumferential direction while following the front side surface 64a and the inner circumferential surface 66.

[0064] As described above, the third layer 62c and the fourth layer 62d are short-width reinforcing layers. Therefore, as shown in Fig. 5, four reinforcing layers 62 extend along the front side surface 64a, and two reinforcing layers 62 extend along the back side surface 64b. The number of reinforcing layers 62 extending along the front side surface 64a is greater than the number of reinforcing layers 62 extending along the back side surface 64b.

[0065] In the embodiment of Fig. 5, the ends of the portions of the third layer 62c and the fourth layer 62d, which are short-width reinforcing layers, along the inner circumferential surface 66 are both located on the equatorial plane CL. The short-width reinforcing layers may extend beyond the equatorial plane CL. The short-width reinforcing layers do not have to reach the equatorial plane CL.

[0066] Each reinforcing layer 62 includes a plurality of cords arranged in parallel. Each cord is inclined with respect to the circumferential direction. In this embodiment, the absolute value of the angle formed by the cords with respect to the circumferential direction in each reinforcing layer 62 is 10° or greater and 80° or less. In two adjacent reinforcing layers 62, the direction of inclination of the cords with respect to the circumferential direction in one reinforcing layer 62 with respect to the circumferential direction is opposite to the direction of inclination of the cords with respect to the circumferential direction in the other reinforcing layer 62 with respect to the circumferential direction. That is, the direction of inclination of the cords with respect to the circumferential direction in the first layer 62a is opposite to the direction of inclination of the cords with respect to the circumferential direction in the second layer 62b, the direction of inclination of the cords with respect to the circumferential direction in the second layer 62b is opposite to the direction of inclination of the cords with respect to the circumferential direction in the third layer 62c, and the direction of inclination of the cords with respect to the circumferential direction in the third layer 62c is opposite to the direction of inclination of the cords with respect to the circumferential direction in the fourth layer 62d.

[0067] For the full-width reinforcing layer and the short-width reinforcing layer that reaches the equatorial plane CL, the inclination angle of the cord is measured at the equatorial plane CL. For the short-width reinforcing layer that does not reach the equatorial plane CL, the inclination angle of the cord is measured at the end on the equatorial plane CL side.

[0068] In the embodiment of Figure 5, the number of full-width reinforcing layers and the number of short-width reinforcing layers are both 2. The number of full-width reinforcing layers may be 1, or 3 or more. The number of short-width reinforcing layers may be 1, or 3 or more. All of the reinforcing layers 62 may be short-width reinforcing layers.

[0069] In the embodiment of Fig. 5, the two full-width reinforcing layers are located closer to the outer surface of the tire 52 than the two short-width reinforcing layers. Some or all of the short-width reinforcing layers may be located closer to the outer surface of the full-width reinforcing layers. The full-width reinforcing layers and the short-width reinforcing layers may be stacked alternately.

[0070] This cushion tire 52 includes a full-width reinforcing layer and a short-width reinforcing layer. The short-width reinforcing layer extends along the front side surface 64a and the inner circumferential surface 66, but not along the rear side surface 64b. Therefore, the number of reinforcing layers 62 extending along the front side surface 64a is greater than the number of reinforcing layers 62 extending along the rear side surface 64b. In cushion tires, deformation of the front side tends to be greater than deformation of the rear side. By increasing the number of reinforcing layers 62 along the front side surface 64a, deformation of the tire 52 is effectively suppressed. This tire 52 achieves excellent durability. By reducing the number of reinforcing layers 62 along the rear side surface 64b, the impact of the reinforcing layers 62 on the mass of the tire 52 is suppressed. This tire 52 can achieve a lighter weight. [Example]

[0071] The effects of the present invention will be clarified below by examples, but the present invention should not be construed as being limited based on the descriptions of these examples.

[0072] [Example 1] A cushion tire of Example 1 was obtained with the specifications shown in Table 1 below. This tire had the configuration shown in Figure 1. This is shown as "Figure 1" in the "Configuration Diagram" column of Table 1. The tire size was "5.00-8 / 3.00D." The rib tip height Hd of this tire was 78 mm, and the flange height Hf of the rim on which this tire was mounted was 18 mm. Therefore, the height Hm (= Hf + (Hd - Hf) / 3) was 38 mm. In the table, the height Ho is shown as the ratio (Hd / Ho) and the ratio (Hm / Ho). The tread hardness of this tire was 65.

[0073] [Comparative Example 1] A tire of Comparative Example 1 was obtained in the same manner as in Example 1, except that no reinforcing layer was provided and the hardness of the base was set to the same as the hardness of the tread.

[0074] Comparative Example 2 A tire of Comparative Example 2 was obtained in the same manner as in Example 1, except that no reinforcing layer was provided. [Example 2-3] A tire of Example 2-3 was obtained in the same manner as Example 1, except that the cord angle θ was set as shown in Table 1.

[0075] [Example 4] The tire of Example 4 had two full-width reinforcing layers. The absolute value of the angle θ of the cords in these reinforcing layers was the same. This value is shown in Table 2 as the cord angle θ. The inclination direction of the cords in one reinforcing layer relative to the circumferential direction was opposite to the inclination direction of the cords in the other reinforcing layer relative to the circumferential direction. Except for these, the tire of Example 4 was obtained in the same manner as Example 1.

[0076] [Example 5] A tire of Example 5 was obtained in the same manner as Example 4, except that the distance Di was set as shown in Table 2. [Example 6] The tire of Example 4 has two full-width reinforcing layers and two short-width reinforcing layers. These short-width reinforcing layers are layered inside the full-width reinforcing layers. The number of reinforcing layers along the front side is four, and the number of reinforcing layers along the back side is two. The ends of the portions of the short-width reinforcing layers along the inner circumferential surface are located on the equatorial plane. The absolute values ​​of the cord angles θ of these four reinforcing layers were the same. In adjacent pairs of reinforcing layers, the inclination direction of the cords of one reinforcing layer relative to the circumferential direction was opposite to the inclination direction of the cords of the other reinforcing layer relative to the circumferential direction. The distance Di was the same for all adjacent pairs of reinforcing layers. This value is shown in the distance Di column in Table 2. Except for these points, the tire of Example 6 was obtained in the same manner as Example 5.

[0077] [Example 7] A tire of Example 7 was obtained in the same manner as Example 1 except that the cord material was steel.

[0078] [Tire deformation] The tire was mounted on a rim (size: 8x3.0D) and attached to the drive wheel of a vehicle (a counterweight-type forklift with a 1.75-ton capacity). No cargo was loaded on the vehicle. The vehicle was subjected to repeated slalom running on a flat asphalt road. The speed of the vehicle was 8 km / h and the running time was 2 hours. After that, the height Hdf of the rib tips on the front side and the height Hdb of the rib tips on the back side were measured. The ratio of these values ​​(Hdf / Hdb) is shown in Table 1-2 as "tire deformation." The closer this value is to 1.00, the smaller the deformation. The closer this value is to 1.00, the more preferable it is.

[0079] [Rim Slip] In the tire deformation evaluation, the length of slippage of the tire against the rim was measured immediately after running. The results are shown in Table 1-2 as an index, with Comparative Example 2 being set at 100. The smaller this value, the better the performance in preventing rim slippage. The smaller the value, the more preferable.

[0080] [Handling stability] During the driving test to evaluate tire deformation, the driver performed a sensory evaluation of the handling stability. The results are shown in Table 1-2 on a five-point scale from 1 to 5. The higher the value, the better.

[0081] [Fever] For the tire deformation evaluation, immediately after running, a hole was drilled from the center of the tread surface toward the inside in the radial direction. The temperature was measured at a position 40 mm deep from the tread surface of the tire before running, and the amount of heat generated by running was calculated. The results are shown in Table 1-2 as an index, with Comparative Example 2 set to 100. The smaller the value, the more heat generation is suppressed. The smaller the value, the more preferable.

[0082] [Durability] As a measure of durability, the state of damage to the tires after running in the tire deformation evaluation was checked. The results are shown in Table 1-2 on a three-point scale of A, B, and C. A is the most preferable, followed by B and C.

[0083] [Table 1]

[0084] [Table 2]

[0085] As shown in Table 1-2, the tires of the examples are generally superior to the tires of the comparative examples. From these evaluation results, the superiority of the present invention is clear. [Industrial Applicability]

[0086] The tire according to the present invention can be mounted on an industrial vehicle. [Explanation of symbols]

[0087] 2, 32, 52 tires 4, 34, 54...assembly 6. Tread surface 8, 40, 66...inner surface 10, 38, 64... Side 12, 42, 56... Tread 14, 44, 58... base 16, 46, 60 beads 18, 36, 62... Reinforcement layer 20...Groove 22, 48... Ribs 24 Bottom 26... Code

Claims

1. A cushion tire whose surface has an inner circumferential surface and a pair of side surfaces, The tire comprises a tread having a tread surface that comes into contact with a road surface, a base located radially inward of the tread, beads embedded in the base and extending in a circumferential direction, and one or more reinforcing layers that include a plurality of cords arranged in parallel and extend in the circumferential direction, The hardness of the base is the same as or greater than the hardness of the tread, Each reinforcing layer has two end points and extends from one end point to the other end point along at least one side surface and the inner circumferential surface, A cushion tire, wherein the reinforcing layer extends beyond the base layer along the side.

2. The reinforcing layer is provided with a plurality of layers, and the reinforcing layers are stacked, the cords of each reinforcing layer are inclined with respect to the circumferential direction, and the absolute value of the angle formed by the cords with respect to the circumferential direction is equal to or greater than 10° and equal to or less than 80°; 2. The cushion tire according to claim 1, wherein, of two adjacent reinforcing layers, the direction of inclination of the cords of one reinforcing layer relative to the circumferential direction is opposite to the direction of inclination of the cords of the other reinforcing layer relative to the circumferential direction.

3. The tire further includes a rib that protrudes outward and extends in a circumferential direction at a boundary between the tread surface and the side surface, There are one or more reinforcing layers extending along the side surfaces; 3. The cushion tire according to claim 1, wherein when the tire is mounted on a rim, a radial height Hf of the flange of the rim, a height Ho of the reinforcing layer, and a radial height Hd of the tip of the rib satisfy the following relationship: Hf+(Hd-Hf) / 3≦Ho≦Hd Here, the height Ho represents the height of the radially outer end of the reinforcing layer when the number of reinforcing layers extending along the side surface is one, and represents the height of the radially outer end of the reinforcing layer located closest to the side surface when the number of reinforcing layers extending along the side surface is two or more.

4. There are a plurality of reinforcing layers extending along the side surfaces, 4. The cushion tire according to claim 1, wherein, for each pair of adjacent reinforcing layers, an outer end of the reinforcing layer located on the side surface side is located radially outward from an outer end of the reinforcing layer located on an inner surface side.

5. 5. The cushion tire according to claim 4, wherein for each pair of reinforcing layers, the distance in the radial direction between an outer end of the reinforcing layer located on the side surface side and an outer end of the reinforcing layer located on the inner side is 3.0 mm or more.

6. 6. A cushion tire according to claim 1, wherein, when the tire is mounted on a vehicle, the number of reinforcing layers along the side surface located in the outer direction of the vehicle is greater than the number of reinforcing layers along the side surface located in the inner direction of the vehicle.

7. The cushion tire according to claim 1 , wherein the cord is made of an organic fiber or steel.

8. A cushion tire is provided with a rim and is attached to the rim, and the surface of the cushion tire has an inner circumferential surface and a pair of side surfaces, The cushion tire comprises a tread having a tread surface that comes into contact with a road surface, a base located radially inward of the tread, beads embedded in the base and extending in a circumferential direction, and one or more reinforcing layers that include a plurality of cords arranged in parallel and extend in a circumferential direction, The hardness of the base is the same as or greater than the hardness of the tread, Each reinforcing layer has two end points and extends from one end point to the other end point along at least one side surface and the inner circumferential surface, the reinforcing layer extends laterally beyond the base layer.

Images