JP7000873B2 - Bias tires for motorcycles - Google Patents

Description

The present invention relates to a bias tire for a motorcycle.

A tire disclosed in Patent Document 1 is known as a tire for a two-wheeled vehicle in which rolling resistance is reduced while ensuring sufficient rigidity. In Patent Document 1, a reinforcing rubber layer is provided inside the shoulder region in the radial direction so that the shoulder region of the tread touches the road surface in a full bank turning run. This reinforcing rubber layer increases the rigidity of the sidewall when turning.

Japanese Unexamined Patent Publication No. 2016-37126

By the way, a motorcycle has a feature different from that of a four-wheeled vehicle in that it can be moved by hand even when the tires are not filled with internal pressure. In particular, when a tire punctures while driving on a rough road and the vehicle cannot travel, the vehicle may be moved by hand. Although it is possible to push the vehicle by hand, there is a problem that it is difficult to push the vehicle when the internal pressure is not applied. Further, even when the vehicle is moved by hand, the durability performance of the tire becomes a problem.

The present invention has been made in view of the above, and an object of the present invention is to provide a bias tire for a motorcycle that maintains the durability performance while improving the hand pushing performance of the vehicle.

In order to solve the above-mentioned problems and achieve the object, the bias tire for a motorcycle according to an embodiment of the present invention has a pair of bead cores and, in the tire meridional cross section, around each of the pair of bead cores from the inside in the tire width direction. After being folded outward in the tire width direction, the carcass layer is wound up from the inside in the tire radial direction to the sidewall portion in the tire radial direction, and in the tire meridional cross section, the position before the turning of the carcass layer is outward in the tire width direction. A rubber reinforcing layer provided on the sidewall portion along the carcass layer is provided, and the rubber reinforcing layer is located at the maximum width position of the carcass layer inside the tire radial direction from the tire maximum width position in the tire meridional cross section. In the tire meridional cross section, the upper end of the rubber reinforcing layer in the tire radial direction is located inside the tire meridional section from the vertical line drawn with respect to the tread surface through the tread end portion, and in the tire meridional cross section, the said The lower end of the rubber reinforcing layer in the tire radial direction is located outside the tire radial direction from the height of the rim flange, and the thickness of the rubber reinforcing layer at the maximum width position of the carcass layer in the tire meridional cross section is the thickness of the carcass layer. It is 10% or more and 80% or less of the thickness of the rubber of the sidewall portion at the maximum width position of.

It is preferable that the modulus of the rubber reinforcing layer at 100% elongation is 2.0 MPa or more and 3.0 MPa or less.

The rubber reinforcing layer is preferably arranged between the position before folding and the position after folding of the carcass layer.

The rubber reinforcing layer may be arranged outside in the tire width direction at a position after the carcass layer is folded back.

The tire cross-sectional height is preferably 22% or more with respect to the rim diameter.

The bias tire for a motorcycle according to the present invention can improve the hand pushing performance of the vehicle and maintain the durability performance.

FIG. 1 is a diagram showing a bias tire for a motorcycle according to an embodiment of the present invention. FIG. 2 is a diagram showing a bias tire for a motorcycle according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, the components of this embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Further, the plurality of modifications described in this embodiment can be arbitrarily combined within a range self-evident by those skilled in the art. In addition, some components may not be used.

FIG. 1 is a cross-sectional view of a meridian of a motorcycle bias tire 100 (hereinafter, appropriately referred to as a tire 100) according to the present embodiment. In the following description, the tire radial direction means a direction orthogonal to the rotation axis (not shown) of the tire 100, the tire radial inner side is the tire radial direction side toward the rotation axis, and the tire radial direction outer side. The side away from the axis of rotation in the tire radial direction. Further, the tire circumferential direction means a circumferential direction with the rotation axis as the central axis. The tire width direction means a direction parallel to the rotation axis, the inside in the tire width direction is the side toward the tire equatorial plane (tire equatorial line) CL in the tire width direction, and the outside in the tire width direction is the tire width direction. Refers to the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane orthogonal to the rotation axis of the tire 100 and passing through the center of the tire width of the tire 100. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equatorial line is a line on the tire equatorial plane CL and along the tire circumferential direction of the tire 100. In the present embodiment, the tire equatorial line is designated by the same reference numeral “CL” as the tire equatorial plane.

In FIG. 1, the tire 100 according to the present embodiment includes a bead portion 1, a carcass layer 2, an inner liner 4, a tread portion 5, and a sidewall portion 6. The bead portion 1 includes a bead core 3. The carcass layer 2 includes two carcass 21 and 22. In the carcass 21 and 22, a plurality of carcass cords (not shown) arranged side by side are coated with coated rubber. The carcass cord is made of steel or organic fiber (such as polyester, rayon or nylon). The inner liner 4 is provided on the lumen side of the carcass layer 2. The sidewall portion 6 is an area between the bead portion 1 and the tread portion 5.

In FIG. 1, two carcass 21 and 22 are mounted on a pair of left and right bead portions 1, 1. The tire 100 has a turn-up structure in which the ends of the carcass 21 and 22 are folded back from the inside to the outside of the tire around the bead cores 3 and 3 in the bead portions 1 and 1. The carcass 21 and 22 have a bias structure in which the carcass cords are inclined at an angle of less than 90 degrees with respect to the tire circumferential direction. For this reason, in the sidewall portions 6 and 6, a cross-ply structure in which the carcass 21 and 22 before being wound and the carcass 21 and 22 after being wound are overlapped and the carcass cords of the respective carcass 21 and 22 intersect with each other. Is doing. Further, in the tread portion 5, the two carcass 21 and 22 overlap each other and their carcass codes intersect with each other.

In FIG. 1, the tire 100 is rim-assembled to the rim 10. The tire 100 has a chafer 8. The chafer 8 is a reinforcing layer that protects the carcass layer 2 from friction with the rim 10. The rim 10 has a rim flange 10F.

The tread portion 5 is made of a rubber material (tread rubber) and is exposed at the outermost side in the tire radial direction of the tire 100, and the surface thereof is the contour of the tire 100. The outer peripheral surface of the tread portion 5, that is, the tread surface that comes into contact with the road surface during traveling, is provided with a groove (not shown).

(Rubber reinforcement layer)
As shown in FIG. 1, the tire 100 is provided with a rubber reinforcing layer 7 on each of the left and right sidewall portions 6 in the tire meridional cross section. The rubber reinforcing layer 7 is provided along the carcass layer 2 (21, 22) on the outside in the tire width direction from the position before the carcass layer 2 (21, 22) is folded back. Further, as shown in FIG. 1, the rubber reinforcing layer 7 is arranged between the position before the folding and the position after the folding of the carcass layer 2 (21, 22). By arranging the rubber reinforcing layer 7 between the position before the carcass layer 2 (21, 22) before turning back and the position after turning back, the strain generated between the carcass 21 and the carcass 22 is alleviated, and the tire 100 is used. Can maintain the durability performance of.

As shown in FIG. 1, the rubber reinforcing layer 7 is provided at a position passing through the maximum width position (height PWh) of the carcass layer 2 inside the tire radial direction from the tire maximum width position (height TWh). The height TWh of the tire maximum width position is the height along the tire radial direction from the position RO corresponding to the rim diameter to the tire maximum width position. The height PWh at the maximum width position of the carcass layer 2 is the height along the tire radial direction from the position RO corresponding to the rim diameter to the maximum width position of the carcass layer 2.

The outermost end 71 of the rubber reinforcing layer 7 in the tire radial direction is located outside the tire radial direction from the end portion 21T of the carcass 21 and outside the tire radial direction from the end portion 22T of the carcass 22. The upper end 71 of the rubber reinforcing layer 7 is located inside the tire radial direction with respect to the perpendicular line 5S drawn with respect to the tread surface through the tread end portion 5T. Therefore, the entire rubber reinforcing layer 7 is located inside the tire radial direction from the height TWh of the tire maximum width position.

Further, in the rubber reinforcing layer 7, the lower end 72, which is the innermost part in the tire radial direction, is located inside the end portion 21T of the carcass 21 in the tire width direction and inside the end portion 22T of the carcass 22 in the tire width direction. .. The lower end 72 of the rubber reinforcing layer 7 is located outside the tire radial direction with respect to the rim flange height RFh. Therefore, the entire rubber reinforcing layer 7 is located outside the tire radial direction with respect to the rim flange height RFh. The rim flange height RFh is the height from the position RO corresponding to the rim diameter to the outermost side of the rim flange 10F in the tire radial direction.

The lower end 72 of the rubber reinforcing layer 7 may be located inside the end portion 21T of the carcass 21 in the tire width direction and outside the end portion 22T of the carcass 22 in the tire width direction. That is, the rubber reinforcing layer 7 may overlap with one or more winding portions of the carcass 21 and the carcass 22 in the tire width direction.

Here, the thickness of the rubber of the sidewall portion 6 at the maximum width position PWh of the carcass layer 2 is G1, and the thickness of the rubber reinforcing layer 7 at the maximum width position PWh of the carcass layer 2 is G2. At this time, the thickness G2 is preferably 10% or more and 80% or less of the thickness G1. By providing the rubber reinforcing layer 7 having such a thickness on the sidewall portion 6, it is possible to reduce both crushing of the tire when the internal pressure is not filled. Therefore, when the tire 100 is punctured, the hand pushing performance of the vehicle can be improved. The thickness G2 is more preferably 20% or more and 50% or less of the thickness G1. If the thickness G2 is made thinner than 10% of the thickness G1, the effect of reducing the amount of crushing of the tire when the internal pressure is not filled cannot be sufficiently obtained. Further, when the thickness G2 is made thicker than 80% of the thickness G1, the difference in rigidity with the surrounding members becomes large, the strain increases, and the durability performance deteriorates.

The modulus of the rubber reinforcing layer 7 at 100% elongation is preferably 2.0 MPa or more and 3.0 MPa or less, and more preferably 2.5 MPa or more and 2.8 MPa or less. If the modulus of the rubber reinforcing layer 7 at 100% extension is lower than 2.0 MPa, the effect of reducing the amount of crushing of the tire when the internal pressure is not filled cannot be sufficiently obtained, which is not preferable. Further, when the modulus of the rubber reinforcing layer 7 at 100% elongation is higher than 3.0 MPa, the strain increases due to the difference in rigidity between the rubber reinforcing layer 7 and the surrounding members, and the durability performance is lowered, which is preferable. do not have. It should be noted that at least one rubber reinforcing layer 7 may be provided at the above positions, and two or more rubber reinforcing layers 7 may be provided. The modulus of the rubber reinforcing layer 7 at 100% elongation is determined in accordance with JIS K6251: 2017.

(Relationship with rim diameter)
Here, the tire 100 is mainly for motorcycle tires having a small displacement of about 12 inches. Therefore, the tire cross-sectional height SH is preferably 22% or more with respect to the rim diameter. The tire cross-sectional height SH is the height from the position RO corresponding to the rim diameter to the top of the tread portion 5. The tire cross-sectional height SH is equal to 1/2 of the difference between the tire outer diameter and the rim diameter.

(Rubber on the bead)
In FIG. 1, the rubber 9 is filled on the outer side of the bead core 3 of the bead portion 1 in the tire radial direction. The rubber 9 is in contact with the bead core 3. The rubber 9 is arranged in a space formed by folding the end portion of the carcass layer 2 in the tire width direction outward at the position of the bead core 3 in the tire width direction. The height of the rubber 9 is lower than the height of the rim flange 10F. That is, the outermost position of the rubber 9 in the tire radial direction is inside the tire radial direction with respect to the outermost position of the rim flange 10F in the tire radial direction. The cross-sectional area of the rubber 9 is smaller than the cross-sectional area of the bead core 3.

Here, the rubber 9 has the same physical properties as the rubber material of other parts of the tire 100. For example, a rubber material having the same physical characteristics as the coated rubber of the carcass 21 and 22 and the rubber material of the bead portion 1 is arranged as the rubber 9. The JIS-A hardness is in the range of 40 or more and 60 or less. JIS-A hardness is determined according to JISK6253-3: 2012.

(Other embodiments)
FIG. 2 is a cross-sectional view of the meridian of the tire 100 according to another embodiment. In FIG. 2, the rubber reinforcing layer 7 is arranged outside the position of the carcass layer 2 (21, 22) after folding in the tire width direction.

In FIG. 2, the rubber reinforcing layer 7 is provided at a position passing through the maximum width position (height PWh) of the carcass layer 2 inside the tire radial direction from the tire maximum width position (height TWh). The upper end 71 of the rubber reinforcing layer 7 is located outside the end portion 21T of the carcass 21 in the tire radial direction and outside the end portion 22T of the carcass 22 in the tire radial direction. The upper end 71 of the rubber reinforcing layer 7 is located inside the tire radial direction with respect to the perpendicular line 5S drawn with respect to the tread surface through the tread end portion 5T.

Further, the lower end 72 of the rubber reinforcing layer 7 is located inside the end portion 21T of the carcass 21 in the tire width direction and inside the end portion 22T of the carcass 22 in the tire width direction. The lower end 72 of the rubber reinforcing layer 7 is located outside the tire radial direction with respect to the rim flange height RFh.

The lower end 72 of the rubber reinforcing layer 7 may be located inside the end portion 21T of the carcass 21 in the tire width direction and outside the end portion 22T of the carcass 22 in the tire width direction. That is, the rubber reinforcing layer 7 may overlap with one or more winding portions of the carcass 21 and the carcass 22 in the tire width direction. The thickness of the rubber reinforcing layer 7 and the modulus at 100% elongation are the same as those of the embodiment described with reference to FIG.

As shown in FIG. 2, even when the rubber reinforcing layer 7 is arranged outside the position of the carcass layer 2 (21, 22) after folding in the tire width direction, the tire is crushed in a state where the tire pressure is not filled. The amount can be reduced and the hand-pushing performance of the vehicle can be improved.

(summary)
Motorcycles have a different feature from four-wheeled vehicles in that they can be moved by hand even when the tires are not filled with internal pressure. However, although it is possible to move the vehicle by hand, there is a problem that it is difficult to push the vehicle when the internal pressure is not applied. In addition, the arrangement of the rubber reinforcing layer 7 leads to the improvement of the ease of pushing the vehicle, but depending on the arrangement of the rubber reinforcing layer 7, there is a concern that a large difference in rigidity may be partially generated at the end thereof and the durability performance may be deteriorated. There is also.
Therefore, by providing the rubber reinforcing layer 7 at an appropriate position as described above, the amount of crushing of the tire when the tire pressure is not filled is reduced, the hand pushing performance of the vehicle is improved, and the durability performance is maintained. It is possible to realize tires for motorcycles.

In this example, the hand-pushing performance and durability performance were evaluated for a plurality of types of pneumatic tires having different conditions. Motorcycle tires with tire sizes 90 / 90-12 were rim-assembled on regular rims and mounted on test vehicles. The number of carcass for all the prepared tires was two.

As for the evaluation of the hand-pushing performance, the tires were attached to the vehicle, and the sensory evaluation of the pushing comfort was performed by the monitor when the vehicle was pushed by hand with no internal pressure. The push performance is evaluated on a scale of 10 and expressed numerically. The larger the value, the easier it is to push and the more comfortable it is to push. It should be noted that the pushing comfort performance in a state where the tire is filled with the regular internal pressure is 10.

Regarding the evaluation of durability performance, after running under the load durability test conditions specified by FMVSS119, which is the US Federal Motor Vehicle Safety Standard, the load factor was increased every 4 hours and the tires were run until they failed. Durability was evaluated by measuring the mileage until the tire failed. The conventional example is expressed as an index based on the standard (100). The larger the value, the more preferable.

In Table 1, the conventional tire does not have a rubber reinforcing layer, and the ratio of the cross-sectional height to the rim diameter is 27%. Further, in Table 1, the tire of Comparative Example 1 has a rubber reinforcing layer, the position of the upper end of the rubber reinforcing layer is below the vertical line at the end of the tread, the rubber reinforcing layer does not pass through the maximum width position of the carcass, and the rubber is rubber. The position of the lower end of the reinforcing layer is above the rim flange height RFh, the thickness of the rubber reinforcing layer is 10% of the rubber thickness of the sidewall, and the modulus of the rubber reinforcing layer when 100% rubber is stretched is 2.0 MPa. The ratio of the tire cross-sectional height to the rim diameter is 27%.

Referring to Examples 1 to 9 in Table 1, the rubber reinforcing layer 7 has a rubber reinforcing layer 7, the position of the upper end 71 of the rubber reinforcing layer 7 is below the vertical line at the tread end, and the rubber reinforcing layer 7 is the maximum width position of the carcass. When the position of the lower end 72 of the rubber reinforcing layer 7 is above the rim flange height RFh and the thickness G2 of the rubber reinforcing layer 7 is 10% or more and 80% or less with respect to the rubber thickness G1 of the sidewall portion 6. It can be seen that good results are obtained.

Further, referring to Examples 1 to 9 in Table 1, when the modulus of the rubber reinforcing layer when the rubber is 100% stretched is 2.0 MPa or more and 3.0 MPa or less, the ratio of the tire cross-sectional height to the rim diameter is It can be seen that good results are obtained when the content is 22% or more.

1 Bead part 2 Carcus layer 3 Bead core 4 Inner liner 5 Tread part 6 Side wall part 7 Rubber reinforcement layer 8 Chafer 9 Rubber 10 Rim 10F Rim flange 21, 22 Carcus 100 Bias tire for motorcycles CL Tire Equator surface

Claims (5)

In the pair of bead cores and the tire meridional cross section, the pair of bead cores were folded back from the inside in the tire width direction to the outside in the tire width direction around each of the pair of bead cores, and then wound up from the inside in the tire radial direction to the outside in the tire radial direction to the sidewall portion. A carcass layer and a rubber reinforcing layer provided on the sidewall portion along the carcass layer are provided on the tire meridional cross section outside the position of the carcass layer before folding back in the tire width direction.
The rubber reinforcing layer passes through the maximum width position of the carcass layer inside the tire radial direction from the tire maximum width position in the tire meridional cross section.
In the tire meridional cross section, the upper end of the rubber reinforcing layer in the tire radial direction is located inside the tire radial direction from the vertical line drawn with respect to the tread surface through the tread end portion.
In the tire meridional cross section, the lower end of the rubber reinforcing layer in the tire radial direction is located outside the tire radial direction from the rim flange height.
In the tire meridional cross section, the thickness of the rubber reinforcing layer at the maximum width position of the carcass layer is 10% or more and 80% or less of the thickness of the rubber of the sidewall portion at the maximum width position of the carcass layer. Bias tires for. The bias tire for a motorcycle according to claim 1, wherein the modulus of the rubber reinforcing layer when 100% stretched is 2.0 MPa or more and 3.0 MPa or less. The bias tire for a motorcycle according to claim 1 or 2, wherein the rubber reinforcing layer is arranged between a position before turning back and a position after turning back of the carcass layer. The bias tire for a motorcycle according to claim 1 or 2, wherein the rubber reinforcing layer is arranged outside in the tire width direction at a position after the carcass layer is folded back. The bias tire for a motorcycle according to any one of claims 1 to 4, wherein the tire cross-sectional height is 22% or more with respect to the rim diameter.

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