JP5529586B2 - tire - Google Patents

Description

  The present invention relates to a tire formed of a top tread rubber that forms a tread portion that contacts the road surface, a side rubber that forms a side portion of the tire, and a side rubber that is disposed between the top tread rubber and the side rubber. About.

  In high-performance tires with a low flatness ratio (for example, 55% or less), the cross-sectional height of the tire is low, so when a load is applied to the tire, a portion that receives a lot of distortion generated in the side portion of the tire, so-called flex The zone is narrow and distortion tends to concentrate locally on a part of the side portion.

  Therefore, instead of forming a tread part that contacts the road surface and shortening the length that the top tread rubber, which has relatively high rigidity, reaches the side part, place the side rubber that is less rigid than the top tread rubber closer to the grounding surface side with the road surface. A tire has been proposed which extends to the flex zone and covers the flex zone. With such a configuration, distortion applied to the side portion is dispersed.

Japanese Patent Laid-Open No. 2006-27474 FIG.

  The conventional tire described above has the following problems. In other words, since the rigidity of the side part affects the responsiveness of the tire, the rigidity of the side part has been lowered for high-performance tires that require stable characteristics even when driving close to the tire performance limit. This led to a decrease in the limit characteristics.

  Accordingly, an object of the present invention is to provide a tire having a flatness ratio of 55% or less and having a high durability while maintaining high running performance.

  In order to solve the above-described problem, the first feature of the present invention is that a pair of bead cores, at least one carcass folded in a toroid shape between the pair of bead cores and folded at the bead core, and a tire diameter of the carcass A tire having a belt disposed outside in a direction, a top tread rubber disposed outside in the tire radial direction of the belt and constituting a tread portion, and a side rubber disposed outside in the tread width direction of the carcass and constituting a side portion. The mini-side rubber is disposed between the top tread rubber and the side rubber and joined to the top tread rubber and the side rubber, and the mini side rubber is joined to the top tread rubber. A tread side end portion and a side side end portion joined to the side rubber; The side end portion is arranged on the outer side in the tire radial direction than the top tread rubber, the side side end portion is arranged on the outer side in the tire radial direction than the side rubber, and the mini side rubber is arranged in the tread width direction of the carcass. The rigidity of the top tread rubber and the rigidity of the mini side rubber is higher than the rigidity of the side rubber, and the flatness is 55% or less. To do.

  In a tire having a flatness ratio of 55% or less, the region of the bead portion side of the side portion region including the carcass maximum width portion of the carcass is more affected by the tire distortion than the region of the tread surface side than the carcass maximum width portion. It is said to be small and has little distortion.

  In the tire according to the present invention, the rigidity of the tire is ensured by disposing the mini side rubber having higher rigidity than the side rubber in the region including the carcass maximum width portion of the carcass located on the outermost side in the tread width direction of the tire. Can do. Further, the side rubber region including at least the carcass maximum width portion of the carcass is a side rubber having rigidity lower than that of the top tread rubber and the mini side rubber in a region closer to the bead portion than the side portion region including the carcass maximum width portion of the carcass. The distortion relating to the side portion is dispersed by the arrangement. Therefore, it is possible to provide a tire with improved durability while maintaining high running performance.

  A second feature of the present invention relates to the first feature of the present invention, wherein the side-side end portion of the mini-side rubber is the top tread rubber from the end portion in the tire radial direction inside the carcass of the carcass maximum width portion. The gist is that the tire is disposed in a range of ± 5% of the tire cross-sectional length SH which is the length to the contact surface between the road surface and the road surface.

  A third feature of the present invention relates to the first feature of the present invention, wherein the thickness of the tread side end portion decreases as the outer surface of the side portion approaches the tread surface along the tire radial direction. In addition, the thickness of the top tread rubber increases as the outer surface of the side portion approaches the tread surface along the tire radial direction, and the thickness of the side side end portion of the tire increases on the outer surface of the side portion. In summary, the thickness of the side rubber decreases as it approaches the bead portion along the radial direction, and the thickness of the side rubber increases as the outer surface of the side portion approaches the bead portion along the tire radial direction. To do.

  A fourth feature of the present invention relates to the third feature of the present invention, wherein the side-side end portion of the mini-side rubber is radially outer in the cross section along the tire radial direction and tread width direction of the tire. And the mini-side inner surface located on the inner side in the tire radial direction, and the angle formed by the mini-side outer surface and the mini-side inner surface is 30 degrees or less. And

  A fifth feature of the present invention relates to the first feature of the present invention, wherein a rim is formed on a part of the side rubber by a rubber material having rigidity lower than the rigidity of the top tread rubber and the mini side rubber. The rim guard which protects is formed, and it makes it a summary to arrange | position the said side side edge part on the outer side of the said rim guard.

  According to the present invention, it is possible to provide a tire having a flatness ratio of 55% or less and having improved durability while maintaining high running performance.

FIG. 1 is a partially enlarged view in which a part of a cross section of a tire according to an embodiment of the present invention is enlarged. FIG. 2 is a schematic view illustrating the distortion applied to the side portion of the tire according to the embodiment of the present invention and the tire structure in association with each other. FIG. 3 is a schematic diagram illustrating the distortion and the tire structure associated with the side portion of the tire according to the modification of the embodiment of the present invention in association with each other.

  An embodiment of a tire according to the present invention will be described with reference to the drawings. Specifically, (1) schematic configuration of pneumatic tire, (2) strain applied to side portion and structure of pneumatic tire, (3) modification, (4) action / effect, (5) other embodiments Will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

(1) Schematic Configuration of Pneumatic Tire FIG. 1 is a partially enlarged view of a part of a cross section of the pneumatic tire 1 according to the embodiment of the present invention. As shown in FIG. 1, the pneumatic tire 1 includes a pair of left and right bead cores 21 constituting a bead portion 11 that contacts a rim portion (not shown) of the wheel, and a bead core 21 straddling a pair of bead cores 21 in a toroidal shape. At least one of the carcass 22 folded back in FIG. 2, a plurality of belt layers 23 disposed on the outer side in the tire radial direction of the carcass 22, a top tread rubber 31 disposed on the outer side in the tire radial direction of the plurality of belt layers 23, and air And side rubber 32 disposed on the outer side of the carcass 22 in the tread width direction on the side surface of the tire 1.

  A rim guard 33 that protects a rim (not shown) is formed on a part of the side rubber 32. The rigidity of the rim guard 33 is lower than the rigidity of the top tread rubber 31 and the rigidity of the mini side rubber 41. In the present embodiment, the side rubber 32 and the rim guard 33 constitute a side portion of the pneumatic tire 1.

  The pneumatic tire 1 has a mini side rubber 41. The mini side rubber 41 is disposed between the top tread rubber 31 and the side rubber 32. The mini side rubber 41 has a tread side end portion 42 joined to the top tread rubber 31 and a side side end portion 43 joined to the side rubber 32.

  In the joint portion between the top tread rubber 31 and the side rubber 32, the tread side end portion 42 is disposed on the outer side in the tire radial direction than the top tread rubber 31. The side-side end portion 43 is disposed on the outer side in the tire radial direction than the side rubber 32.

  The mini side rubber 41 is disposed in a region including the maximum width portion 22M of the carcass 22 located on the outermost side in the tread width direction. The rigidity of the top tread rubber 31 and the rigidity of the mini side rubber 41 are higher than the rigidity of the side rubber 32.

  The side-side end portion 43 of the mini side rubber 41 is a length from the end portion 22a on the inner side in the tire radial direction of the carcass 22 to the contact surface (tread surface 31A) between the top tread rubber 31 and the road surface with respect to the maximum width portion 22M. It is arrange | positioned in the range of +/- 5% of tire cross-sectional length SH which is.

  The thickness of the tread side end portion 42 decreases as the outer side of the pneumatic tire 1 approaches the tread surface 31A along the tire radial direction. Further, the thickness of the top tread rubber 31 increases as the outside of the pneumatic tire 1 approaches the tread surface 31A along the tire radial direction. Further, the thickness of the side-side end portion 43 decreases as the outside of the pneumatic tire 1 approaches the bead portion 11 along the tire radial direction, and the thickness of the side rubber 32 extends from the outside of the pneumatic tire 1 to the tire. It increases as it approaches the bead part 11 along a radial direction.

  In the cross section along the tire radial direction and tread width direction of the pneumatic tire 1, the side-side end portion 43 of the mini-side rubber 41 is located on the mini-side outer surface 43 o located on the tire radial direction outer side and on the tire radial direction inner side. And a mini-side inner side surface 43i. In the cross section along the tire radial direction and tread width direction of the pneumatic tire 1, the angle θ formed by the mini-side outer surface 43o and the mini-side inner surface 43i is preferably 30 degrees or less. The rubber thickness D shown in FIG. 1 will be described later.

  In addition, the flat rate of the pneumatic tire 1 is 55% or less. The pneumatic tire 1 may be filled with an inert gas such as nitrogen in addition to air.

(2) Strain applied to the side portion and structure of the pneumatic tire FIG. 2 is a schematic diagram illustrating the distortion applied to the side portion of the pneumatic tire 1 according to the embodiment of the present invention and the tire structure in association with each other. . The graph shown on the left side of FIG. 2 shows the position of the side portion and the distortion applied to that position when a predetermined load is applied to the pneumatic tire 1. The vertical axis in FIG. 2 is associated with the position of the side portion of the pneumatic tire 1 shown on the right side of FIG.

  As shown in FIG. 2, in the pneumatic tire 1 according to the present embodiment, a portion of the side portion closer to the tread surface 31 </ b> A than the maximum width portion 22 </ b> M has a higher rigidity than the side rubber 32 in a portion where the distortion is maximized. Side rubber 41 is disposed. Further, a side rubber 32 having rigidity lower than that of the mini side rubber 41 is provided in the vicinity of the maximum width portion 22M where the strain is close to 0% even when a predetermined load is applied, and on the inner side in the tire radial direction from the position corresponding to the maximum width portion 22M. Arranged.

(3) Modified Example FIG. 3 is a schematic diagram illustrating the distortion and the tire structure associated with the side portion of the tire according to a modified example of the embodiment of the present invention. In the pneumatic tire 2 shown in FIG. 3, the side end 43 is extended to the outside of the rim guard 33. Specifically, the side-side end portion 43 reaches the apex of the rim guard 33, that is, the outermost side in the tread width direction of the pneumatic tire 2.

  Also in this case, a mini side rubber 41 having a rigidity higher than that of the side rubber 32 is disposed in a portion where the distortion is maximized in the side portion closer to the tread surface 31A than the maximum width portion 22M. Further, a side rubber 32 having rigidity lower than that of the mini side rubber 41 is provided in the vicinity of the maximum width portion 22M where the strain is close to 0% even when a predetermined load is applied, and on the inner side in the tire radial direction from the position corresponding to the maximum width portion 22M. Arranged.

(4) Action / Effect According to the pneumatic tire 1 according to the embodiment of the present invention, the mini side rubber having higher rigidity than the side rubber 32 in the region including the maximum width portion 22M located on the outermost side in the tread width direction of the carcass 22. By arranging 41, the rigidity of the tire can be ensured. Further, by arranging the side rubber 32 having rigidity lower than that of the top tread rubber 31 and the mini side rubber 41 in the region closer to the bead portion than the region including at least the maximum width portion 22M, the distortion related to the side portion is dispersed. . Therefore, it is possible to provide a tire with improved durability while maintaining high running performance.

  Further, in the pneumatic tire 1, the side-side end portion 43 of the mini side rubber 41 is arranged in a range of ± 5% of the tire cross-sectional length SH at the maximum width portion 22M. As a result, the joint surface between the side-side end portion 43 and the side rubber 32 is located in the vicinity of the maximum width portion 22M where the strain is close to 0% even when a predetermined load is applied to the pneumatic tire 1, so the load applied to the joint surface Can be reduced. Thereby, generation | occurrence | production of the crack which is easy to generate | occur | produce in the joint surface of rubber | gum from which rigidity differs is suppressed, and durability of the pneumatic tire 1 can be improved.

  In the pneumatic tire 1, the thickness of the tread side end portion 42 decreases as it approaches the tread surface 31A, and the thickness of the top tread rubber 31 increases as it approaches the tread surface 31A. Further, the thickness of the side-side end portion 43 decreases as it approaches the bead portion 11 along the tire radial direction, and the thickness of the side rubber 32 increases as it approaches the bead portion 11 along the tire radial direction. To do. In the pneumatic tire 1, the angle formed between the mini-side inner side surface 43 i and the mini-side outer side surface 43 o at the side-side end portion 43 of the mini-side rubber 41 is 30 degrees or less.

  According to such a configuration, since the bonding area between the top tread rubber 31 and the mini side rubber 41 or the bonding area between the side rubber 32 and the mini side rubber 41 can be increased, the bonding property between the rubbers can be improved. .

  Further, for example, when the maximum width portion 22M is covered only with the side rubber 32, it is necessary to increase the thickness of the side rubber 32 in order to ensure the prescribed rigidity. In the case of the tire 2 as well, since the rigidity in the maximum width portion 22M portion can be secured by providing the mini side rubber 41, as a result, the total thickness of the rubber material in the side portion (rubber thickness D in FIG. 1) is reduced. Can do. Thereby, the cost for manufacturing the pneumatic tire 1 can be reduced, and the weight of the pneumatic tire 1 can be reduced.

(5) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments and examples will be apparent to those skilled in the art. For example, the embodiment of the present invention can be modified as follows.

  For example, in the present embodiment, it has been described that the flatness of the pneumatic tire 1 is 55% or less, but a mini-side rubber having rigidity higher than that of the side rubber is disposed in a region including the carcass maximum width portion, and is more than that of the side rubber. It is only necessary to have a structure that is joined to the outer side in the tire radial direction, and the same effect can be obtained even when the flatness ratio exceeds 55%.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  In order to clarify the effects of the present invention, pneumatic tires according to Examples 1 and 2 were manufactured and comparative evaluation tests were performed.

  Example 1 is the pneumatic tire shown in FIG. Example 2 is the pneumatic tire of the modified example described in FIG. Comparative Example 1 is a conventional tire in which the side rubber is extended to the end of the top tread rubber.

  Various performances of each pneumatic tire were measured under the following conditions.

・ Tire size: 225 / 40R18
・ Drum: Internal pressure condition 130kPa, load 450kg, traveling 20,000km
-Actual vehicle: Internal pressure condition 180kPa, camber angle -2 °, load driver 1 person + 70kg, travel 20,000km, general passenger car (displacement 1.500cc)
-Side surface strain test: Internal pressure condition 130 kPa, load 560 kg
The rim and internal pressure are based on an applicable rim and air pressure-load capacity correspondence table corresponding to the size of the radial ply tire defined in JATMA YEARBOOK (2008 Japan Automobile Tire Association Standard). The state of cracks in the joint portion of the top tread rubber, side rubber, and mini side rubber after traveling for a predetermined distance (20,000 km) was visually confirmed. The results are shown in Table 1. The result is represented by an index with the result of the conventional tire as 100.

  As shown in Table 1, in the tire of Comparative Example 1, cracks were confirmed in the joined portions of the top tread rubber, the side rubber, and the mini side rubber. In contrast, the tires of Examples 1 and 2 were not inferior in durability. The tire of Example 1 was found to be able to reduce the overall weight compared to the tire of Example 2.

  DESCRIPTION OF SYMBOLS 1, 2 ... Pneumatic tire, 11 ... Bead part, 21 ... Bead core, 22 ... Carcass, 22M ... Maximum width part, 22a ... End part, 23 ... Belt layer, 31 ... Top tread rubber, 31A ... Tread surface, 32 ... Side rubber, 33 ... Rim guard, 41 ... Mini side rubber, 42 ... Tread side end, 43 ... Side side end, 43i ... Mini side inner side, 43o ... Mini side outer side

Claims (6)

A pair of bead cores, at least one carcass folded in the bead core between the pair of bead cores in a toroidal shape, a belt disposed on the outer side in the tire radial direction of the carcass, and on the outer side in the tire radial direction of the belt A tire having a top tread rubber arranged and constituting a tread portion, and a side rubber arranged outside the carcass in the tread width direction and constituting a side portion;
A mini-side rubber disposed between the top tread rubber and the side rubber and joined to the top tread rubber and the side rubber;
The mini side rubber is
A tread side end joined to the top tread rubber;
A side-side end joined to the side rubber;
The tread end portion is disposed on the outer surface of the tire side of the front SL top tread rubber,
The side end portion is disposed on the outer surface of the tire side of the front SL side rubber,
The mini side rubber is disposed on the outer surface of the tire in the carcass maximum width portion located on the outermost side in the tread width direction of the carcass,
A tire in which the rigidity of the top tread rubber and the rigidity of the mini side rubber are higher than the rigidity of the side rubber, and the flatness ratio is 55% or less. The side end portion of the mini side rubber has a tire cross-section length SH that is a length from the inner end portion in the tire radial direction of the carcass to the ground contact surface of the top tread rubber and the road surface with respect to the carcass maximum width portion . The tire according to claim 1, wherein the tire is arranged in a range of ± 5%.   In the region extending in the tread width direction from the carcass maximum width portion located on the outermost side in the tread width direction of the carcass, the side rubber and the mini side rubber are arranged,
  The tire according to claim 1 or 2, wherein an inner end portion in the tire radial direction of the top tread rubber is located on an outer side in the tire radial direction with respect to an outer end portion in the tire radial direction of the side rubber. The thickness of the tread side end portion decreases as the outer side surface of the side portion approaches the tread surface along the tire radial direction, and the thickness of the top tread rubber increases the tire outer diameter of the side portion. Increases as you approach the tread surface along the direction,
The thickness of the side end portion decreases as the outer surface of the side portion approaches the bead portion along the tire radial direction, and the thickness of the side rubber increases the outer surface of the side portion in the tire radial direction. The tire according to claim 1, wherein the tire increases as the bead portion approaches. In the cross section along the tire radial direction and tread width direction of the tire, the side-side end portion of the mini-side rubber includes a mini-side outer surface located on the outer side in the tire radial direction and an inner side on the mini-side located on the inner side in the tire radial direction. And have side faces,
The tire according to claim 4 , wherein an angle formed by the mini-side outer surface and the mini-side inner surface is 30 degrees or less. A rim guard that protects the rim is formed on a part of the side rubber with a rubber material having rigidity lower than that of the top tread rubber and the rigidity of the mini side rubber,
The tire according to claim 1, wherein the side-side end portion reaches the apex of the rim guard, that is , the outermost side in the tread width direction of the tire.

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