JP4133210B2 - Tires for motorcycles - Google Patents

Description

【００４２】
表１に示す結果から、実施例のタイヤは、剛性感を損なうことなく、操縦安定性および弾性発泡体の耐久性のいずれもが優れていることが分かる。
【００４３】
【発明の効果】
この発明により、弾性発泡体の耐久性と操縦安定性の双方に優れた二輪車用タイヤを提供することが可能となった。
【図面の簡単な説明】
【図１】 この発明に従う代表的な二輪車用タイヤの幅方向右半断面図である。
【図２】 この発明に従う他の代表的な二輪車用タイヤの幅方向右半断面図である。
【図３】 この発明に従う他の代表的な二輪車用タイヤの幅方向右半断面図である。
【図４】 従来の二輪車用タイヤの幅方向右半断面図である。
【図５】 従来の二輪車用タイヤの幅方向右半断面図である。
【図６】 比較例の二輪車用タイヤの幅方向右半断面図である。
【符号の説明】
１ タイヤ
２ ビードコア
３ ビード部
４ サイドウォール部
５ トレッド部
６ カーカス
７ ブロック
８ 弾性発泡体
９ａ、９ｂ アッププライ
１０ ダウンプライ
１１ 最幅アッププライ折返し端位置
１２ リム径ライン位置
１３ クラウン部
１４ 第１補強層
１５ 第２補強層
１６ 第１補強層端縁位置
ＣＬ タイヤ赤道面
ＴＷ トレッド幅
ＳＨ タイヤ断面高さ[0001]
BACKGROUND OF THE INVENTION
This invention has a block pattern in a tread portion, a negative rate of 70 to 85%, and a tire for a motorcycle, particularly off-road, in which an elastic foam is filled inside a cavity formed in the state of a tire wheel. The present invention relates to an on-road and off-road motorcycle bias tire excellent in durability and handling stability of the elastic foam.
[0002]
[Prior art]
When a motorcycle runs on rough terrain with gravel, rubble, bedrock, etc., so-called off-road, there is a high risk of puncture due to repeated local deformation of tires due to severe road changes. In addition, in the motocross race, in addition to the above reasons, the tire may be locally deformed at the time of landing after the jump, and the tube may be compressed and punctured.
[0003]
As measures for preventing punctures during off-road driving, for example, Patent Documents 1 and 2 describe a tire in which an elastic foam is filled in a tire lumen surrounded by a tire and a rim. The elastic foam tends to break down due to excessive heat generation due to the impact from the road surface to the block defined in the tread portion of the tire by high-speed running for a long time. For this reason, it is necessary in terms of durability to adopt a tire structure that protects the elastic foam, but Patent Documents 1 and 2 do not describe such a tire structure.
[0004]
Conventional motorcycle tires generally employ a bias carcass 103 composed of a plurality of up plies 101 and down plies 102 as shown in FIG. 4, for example. However, such a tire structure tends to concentrate the impact input particularly directly under the block 104, and the elastic foam 105 located in such a portion is locally heated, resulting in poor durability.
[0005]
As a tire structure for protecting the elastic foam 105, for example, as shown in FIG. 5, in addition to the bias carcass 103 adopting the up-down ply structure, a cord is provided on the outer periphery of the crown portion 106 of the bias carcass 103. Is formed by laminating a plurality of cord rubber coating layers 107a and 107b arranged at a small angle (an angle close to 0 °) with respect to the tire circumferential direction so that the cords cross each other across the tire equatorial plane CL. It is useful to arrange That is, the impact input to the elastic foam 105 when the block 104 is grounded can be dispersed in the tire circumferential direction to suppress local heat generation of the elastic foam 105.
[0006]
However, since the cross breaker 108 is usually disposed only in the crown portion region of the carcass 103 around the center region of the tread portion, the tire portion in which the cross breaker 108 is disposed and the tire in which the cross breaker 108 is not disposed. Part, more specifically, a step in rigidity occurs at the tire part between the edge 109 of the cross breaker 108 and the folded end 110 of the carcass ply, and as a result, the shoulder is not strutted and sufficient lateral grip is obtained. Since power cannot be obtained, steering stability is inferior.
[0007]
[Patent Document 1]
Japanese Patent No. 2804266 [Patent Document 2]
JP 2001-18610 A [Patent Document 3]
Japanese Patent Laid-Open No. 2002-67635
[Problems to be solved by the invention]
An object of the present invention is to provide a tire for a motorcycle that is excellent in both durability and handling stability of an elastic foam by optimizing a reinforcing layer, and in particular, provides a bias tire for a motorcycle for both on-road and off-road use. There is to do.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a toroid covering a pair of bead portions in which a bead core is embedded, a pair of sidewall portions extending outward in the tire radial direction from the bead portion, and a tread portion extending between both sidewall portions. For a two-wheeled vehicle comprising a carcass extending in a shape, having a plurality of blocks formed in a tread portion, a negative rate of 70 to 85%, and an elastic foam filled in a cavity formed in the state of a tire wheel In the tire, the carcass is a ply formed by rubber-covering a cord extending at an angle of 30 to 50 ° with respect to the tire equatorial plane, and is at least one folded around the bead core from the inner side to the outer side in the tire width direction. Up ply, and at least one down ply covering the outer surface of the up ply, The distance measured along the tire radial direction between the folded edge of the widest up ply and the rim diameter line position where the folded end is located on the outermost side in the tire radial direction is the tire cross-section height. 30% to 70%, and a first reinforcing layer and a second reinforcing layer formed by rubber covering a cord having a lower elongation than the ply cord are provided on the crown portion of the carcass, and the first reinforcing layer is provided on the outer circumferential side of the carcass. And the end edge positions thereof overlap each other by the length of the tire radial direction which coincides with the positions of the two folded ends of the widest up ply or is 20% or less of the tire cross-section height, The second reinforcing layer is disposed substantially symmetrically across the tire equatorial plane, and the width measured along the tire width direction is 35 to 55% of the tread width, Code It is a two-wheeled vehicle tire, characterized in that to extend at an angle of 25 ° or less with respect ya equatorial plane.
[0010]
Here, each dimension is measured in a no-load state in which a tire is assembled to a standard rim at an applicable size described in JATMA or a standard conforming thereto, and the highest air pressure defined in the standard is applied in the tire. To do. The “rim diameter line position” means a rim diameter measurement position. The elongation of the cord means a constant load elongation measured under a room temperature condition of 25 ± 2 ° C. according to JIS L1017.
[0011]
Moreover, it is preferable that the apparent specific gravity of the elastic foam is 0.1 to 0.2 and the resilience is 50 to 80%. Here, “apparent specific gravity” means specific gravity measured including bubbles of an elastic foam, and “rebound resilience” means using a trypso-type rebound resilience test device according to JIS K6255-1996. Says the measured value (%).
[0012]
Furthermore, it is preferable that the cords constituting the first reinforcing layer and the second reinforcing layer are made of aromatic polyamide or steel.
[0013]
Furthermore, it is preferable that the second reinforcing layer is located on the outer peripheral side of the crown portion of the first reinforcing layer.
[0014]
In addition, it is preferable that the second reinforcing layer is located on the inner peripheral side of the crown portion of the carcass.
[0015]
In addition, the cord constituting the carcass is preferably made of nylon or polyethylene terephthalate.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a right half section in the width direction of a typical motorcycle tire (hereinafter referred to as “tire”) according to the present invention.
[0017]
A tire 1 shown in FIG. 1 includes a pair of bead portions 3 in which a bead core 2 is embedded, a pair of sidewall portions 4 that extend outward from the bead portion 3 in the tire radial direction, and a tread portion 5 that extends across both sidewall portions 4. The carcass 6 extending in a toroidal shape is provided, a plurality of blocks 7 are defined in the tread portion 5, the negative rate is 70 to 85%, and the elastic foam 8 is provided inside the cavity formed in the state of the tire wheel. Filled.
[0018]
The main structural feature of the present invention is a ply in which the carcass 6 is rubber-coated with a cord extending at an angle of 30 to 50 ° with respect to the tire equatorial plane CL. At least one upply that is folded back from the inner side in the width direction, in FIG. 1, at least one upply that covers the outer surfaces of the two upplies 9a and 9b and the upplies 9a and 9b, and 1 in FIG. Of the up plies 9a and 9b that are composed of a single down ply 10 and constitute the carcass 6, the folded end edge 11 and the rim diameter line position 12 of the widest up ply 9a whose folded end is located on the outermost side in the tire radial direction. The distance h measured between the tires along the tire radial direction is 30 to 70% of the tire cross-section height SH, and the crown portion 13 of the carcass 6 is A first reinforcing layer 14 and a second reinforcing layer 15 formed by rubber covering a low elongation cord are provided, and the first reinforcing layer 14 is located on the outer peripheral side of the carcass 6, and both end edge positions 16 thereof are respectively The cord is overlapped by the tire radial direction length d which coincides with the both folded end positions 11 of the widest up ply 9a or is 20% or less of the tire cross-section height SH, and the cord is at an angle of 35 ° or less with respect to the tire equatorial plane CL. The second reinforcing layer 15 is disposed substantially symmetrically across the tire equatorial plane CL, and the width w measured along the tire width direction is 35 to 55% of the tread width TW. It is to extend at an angle of 25 ° or less with respect to the equator plane CL.
[0019]
Hereinafter, how the present invention has adopted the above configuration will be described together with the operation. In a tire having a so-called block pattern in which a plurality of blocks 7 are formed in the tread portion 5, when the block 7 contacts the ground, the tread portion 5 is bent in the tire radial direction, that is, in the direction in which the elastic foam 8 is crushed. A so-called impact occurs. If high-speed running is continued for a long time, excessive heat is generated particularly in the tire crown portion of the elastic foam 8 due to the impact, and the elastic foam tends to deteriorate or break down.
[0020]
In order to prevent this, as shown in FIG. 5, a plurality of cord rubber covering layers 107a in which cords are arranged on the outer periphery of the crown portion 106 of the carcass 103 at a small angle (an angle close to 0 °) with respect to the tire circumferential direction. 107b may be arranged such that the cords cross each other across the tire equatorial plane CL, and the cross breaker 108 may be disposed to disperse the impact from the outside in the tire circumferential direction. A large rigidity step is generated between the tread center portion where the cross breaker 108 is disposed and the tread shoulder portion where the cross breaker 108 is not disposed. In general, when cornering a motorcycle, the tire is given a camber angle and the tread shoulder is grounded, so that the rigid step is cornering due to insufficient steering stability, especially in the tire width direction. It was the cause of the decline of sex.
[0021]
Therefore, as shown in FIG. 1, the inventor effectively disperses the impact in the tire circumferential direction before the tread portion 5 bends inward in the tire radial direction due to the impact, and localizes the elastic foam 8. In order to effectively suppress heat generation, the first reinforcing layer 14 and the first reinforcing layer 14 are arranged on the crown portion 13 of the carcass 6 at a small angle with respect to the tire circumferential direction and are covered with a rubber having a lower elongation than the ply cord. (2) Adopting a configuration in which the reinforcing layer 15 is provided, extending the first reinforcing layer 14 to the side wall portion 4 and extending the first reinforcing layer edge position 16 to the maximum width up In order to complete the present invention, it is found that the configuration can be made as small as possible by matching or overlapping with the folded edge 11 of 9a, and as a result, both durability and steering stability can be improved. Than it was Tsu.
[0022]
If the tire has a negative rate of less than 70%, the groove area becomes too small, and there is a risk that the soil removal will be reduced and the action of the block edge will be suppressed, resulting in insufficient grip on soft road surfaces. In the case where it exceeds 1, the land area becomes too small and the block rigidity is lowered, which may cause insufficient grip on a hard road surface, insufficient durability, and steering stability.
[0023]
When the extension angle with respect to the tire equatorial plane CL is less than 30 °, the cord constituting the carcass 6 has a reduced steering stability due to a decrease in rigidity in the tire width direction. Since the traction is insufficient due to the lowering of rigidity, the angle is set to 30 to 50 °.
[0024]
When the distance measured along the tire radial direction from the rim diameter line position 12 is less than 30% of the tire cross-section height SH, the reinforcing edge around the bead portion is reduced. However, when the durability is insufficient and exceeds 70%, the folded edge 11 is positioned below the tread surface and the steering stability is lowered.
[0025]
If the overlap width between the first reinforcing layer edge position 16 and the turn-up edge 11 of the widest upply 9a exceeds 20%, the tire radial rigidity becomes excessively high and the ride comfort is lowered. 20% or less.
[0026]
The lower limit value of the extension angle of the cords of the first reinforcing layer 14 and the second reinforcing layer 15 is not particularly limited when vulcanization is performed using a split mold including a plurality of segments, and the tire equatorial plane CL However, when the vulcanization is performed by a full mold, the second reinforcement layer 15 is set to 15 ° with respect to the tire equatorial plane CL due to the restriction of the diameter expansion rate during the vulcanization molding. The first reinforcing layer 14 having a width wider than 15 needs to be slightly larger than that of the second reinforcing layer 15, and is preferably set to 25 °.
[0027]
The upper limit value of the extension angle of the cords of the first reinforcing layer 14 and the second reinforcing layer 15 is set to 35 ° in the first reinforcing layer 14 from the viewpoint of the protective effect of the elastic foam 8 and the elimination of the rigidity step in the crown portion 13. In the second reinforcing layer 15, the angle is set to 25 ° from the viewpoint of the protective effect of the elastic foam 8.
[0028]
When the width measured along the tire width direction is less than 35% of the tread width, the second reinforcing layer 15 lacks the impact prevention effect of the elastic foam 8 by the block 7 on the tread portion tread, and 55% In the case where it exceeds 1, the rigidity of the tread surface becomes too high, and the steering stability is lowered.
[0029]
The elastic foam 8 preferably has an apparent specific gravity of 0.1 to 0.2 and a resilience of 50 to 80%. This is because when the apparent specific gravity is less than 0.1, the ratio of the bubbles in the elastic foam 8 is too large and the load supporting ability is inferior, and when it exceeds 0.2, the weight increases and the impact resistance decreases. Because it leads to. Further, if the impact resilience is less than 50%, the rigidity of the tire is too low and steering stability is lacking. If it exceeds 80%, the rigidity of the tire is too high and the riding comfort is poor. Because.
[0030]
The material of the elastic foam 8 is not particularly limited as long as it has the above-mentioned characteristics. For example, natural rubber, styrene-butadiene copolymer, cis-1,4-polyisoprene, cis-1 Diene-based synthetic rubber such as 1,4-polybutadiene can be used.
[0031]
Moreover, it is preferable that the cord which comprises the 1st reinforcement layer 14 and the 2nd reinforcement layer 15 consists of non-extensible aromatic polyamide or steel.
[0032]
Further, for example, as shown in FIG. 3, the second reinforcing layer 15 is disposed between the carcass 6 and the first reinforcing layer 14 or between the plies 9a, 9b, and 10 constituting the carcass 6 (not shown). However, from the viewpoint of workability at the time of molding, it is preferable that the second reinforcing layer 15 is located on the outer peripheral side of the crown portion 13 of the first reinforcing layer 14 as shown in FIG. 2, that is, from the viewpoint of improving the bending rigidity of the tread surface, the second reinforcing layer 15 is preferably positioned on the inner peripheral side of the crown portion 13 of the carcass 6. .
[0033]
Furthermore, it is preferable that the cord constituting the carcass 6 is made of nylon or polyethylene terephthalate. This is because the durability, steering stability and riding comfort of the tire can be simultaneously achieved at a high level.
[0034]
In addition, the configuration of the carcass 6 is preferably two up-plies from the viewpoint of optimizing the rigidity of the sidewall portion 4 and ensuring the durability, and the appropriate rigidity from the tread portion tread surface to the sidewall portion. From the standpoint of making it easier, it is preferable to use a single downply, and from the viewpoint of achieving both tire cushioning and traction on rough terrain, it is preferable to use a bias carcass.
[0035]
The above description is merely an example of the embodiment of the present invention, and various modifications can be made within the scope of the claims.
[0036]
For example, the edge position 16 of the first reinforcing layer 14 may be disposed on the inner side in the tire width direction of the widest up ply 9a.
[0037]
【Example】
Next, a motorcycle tire according to the present invention was prototyped and performance evaluation was performed, which will be described below.
[0038]
The tire of the example has the structure shown in FIG. 1, the tire size is 140 / 90-18, and the distance measured along the tire radial direction between the folded edge of the widest up ply and the rim diameter line position. Is 60% of the tire cross-sectional height, the overlap width of the first reinforcement layer and the widest upply is 10 mm, the overlap amount is 14%, the width of the second reinforcement layer is 70 mm, The extending angles of the cords constituting the reinforcing layer and the second reinforcing layer are 25 ° and 20 °, respectively, with respect to the tire equator plane, and the cord constituting the upply is made of polyester having a 1500d / 2 × 2 structure, The number of cords to be driven is 22 / 25mm, the extension angle of the cord is ± 34 ° with respect to the tire equatorial plane, and the cord constituting the down ply is made of 840d / 2 × 1 structure nylon The number of driven cords is 25/25 mm, the extending angle of the cord is 34 ° with respect to the tire equatorial plane, and the cords constituting the first reinforcing layer and the second reinforcing layer have a 1500 d / 2 × 1 structure. Made of aromatic polyamide, the number of cords to be driven is 18/25 mm for the first reinforcement layer, 22/25 mm for the second reinforcement layer, and the extension angle of the cord with respect to the tire equatorial plane is 25 for the first reinforcement layer. This is a bias tire for a motorcycle in which the second reinforcing layer is 20 °, and a 140 / 90-18 size butyl rubber foam is compression-filled as an elastic foam.
[0039]
For comparison, two up plies and two down plies shown in FIG. 4 and a tire without a reinforcing layer (conventional example 1) and a width measured along the tire width direction shown in FIG. And 60 mm, the extension angles of the cords are both 20 ° with respect to the equatorial plane CL, and a tire in which two reinforcing layers made of the same material as in the example are disposed only on the tire crown (conventional example 2) ), And the distance measured along the tire radial direction between the folded edge of the widest up ply and the rim diameter line position shown in FIG. 6 is 60% of the tire cross-section height, and the extension angle of the cord is Both are 20 ° with respect to the equatorial plane CL, two reinforcing layers made of the same material as in the example are provided, and the tire radial direction between the edge of the first reinforcing layer and the edge of the widest up ply Distance is 30mm, ie tire cross section A tire (comparative example) having a width of 70 mm measured along the tire width direction of the second reinforcing layer and spaced by 25% of the height in the tire radial direction was also prototyped. In the tires of the conventional examples 1 and 2 and the comparative example, the cords constituting the up-ply and the down-ply are all made of the same material as in the examples, and the extension angles thereof are the same as those in the examples. This is a bias tire for a motorcycle in which a 140 / 90-18 size butyl rubber foam is compressed and filled as a body.
[0040]
About each said test tire, steering stability, rigidity, and durability of the elastic foam were evaluated. Steering stability and rigidity are as follows. Each test tire is assembled on a rim with a size of 2.50 × 18 to form a tire wheel, elastic foam is compression-fitted (no air filling), tire load: 1 passenger The motorcycle was mounted on a motorcycle with a displacement of more than 600 cc under considerable load conditions, traveled on rough terrain, and the feeling was evaluated by two professional riders. Further, the durability of the elastic foam was determined by compressing and mounting the elastic foam (no air filling), and running on the drum tester for 6 hours under the conditions of tire load: equivalent to 1 person riding and running speed of 120 km / h. Thereafter, the tire was disassembled and evaluated by the presence or absence of failure of the elastic foam. The evaluation results are shown in Table 1. Steering stability and rigidity are exponential ratios on a 5-point scale, with the value of Conventional Example 1 being three points. The larger the value, the better the steering stability and rigidity.
[0041]
[Table 1]

[0042]
From the results shown in Table 1, it can be seen that the tires of the examples are excellent in both handling stability and durability of the elastic foam without impairing the rigidity.
[0043]
【The invention's effect】
According to the present invention, it is possible to provide a motorcycle tire excellent in both durability and handling stability of an elastic foam.
[Brief description of the drawings]
FIG. 1 is a right half cross-sectional view in the width direction of a typical motorcycle tire according to the present invention.
FIG. 2 is a right half sectional view in the width direction of another typical motorcycle tire according to the present invention.
FIG. 3 is a right half sectional view in the width direction of another typical two-wheeled vehicle tire according to the present invention.
FIG. 4 is a right half sectional view of a conventional motorcycle tire in the width direction.
FIG. 5 is a right half cross-sectional view of a conventional motorcycle tire in the width direction.
FIG. 6 is a right half sectional view in a width direction of a motorcycle tire of a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tire 2 Bead core 3 Bead part 4 Side wall part 5 Tread part 6 Carcass 7 Block 8 Elastic foam 9a, 9b Up ply 10 Down ply 11 Widest up ply return end position 12 Rim diameter line position 13 Crown part 14 First reinforcement Layer 15 Second reinforcement layer 16 First reinforcement layer edge position CL Tire equatorial plane TW Tread width SH Tire cross-section height

Claims (6)

A pair of bead portions with embedded bead cores, a pair of sidewall portions extending outward from the bead portion in the tire radial direction, and a tread portion extending between both sidewall portions, and a carcass extending in a toroid shape, and a plurality of tread portions In a two-wheeled vehicle tire in which a block is formed, a negative rate is 70 to 85%, and an elastic foam is filled in a cavity formed in a state of a tire wheel,
The carcass is a ply formed by rubber-covering a cord extending at an angle of 30 to 50 ° with respect to the tire equatorial plane, and is at least one upply that is folded around the bead core from the inner side to the outer side in the tire width direction. , And at least one down ply that covers the outer surface of the up ply, and among the up plies constituting the carcass, the folded end edge and rim diameter of the widest up ply with the folded end positioned on the outermost side in the tire radial direction The distance measured along the tire radial direction between the line positions is 30 to 70% of the tire cross-section height,
A first reinforcing layer and a second reinforcing layer formed by rubber covering a cord having a lower elongation than the ply cord are provided on the crown portion of the carcass,
The first reinforcing layer is located on the outer peripheral side of the carcass, and both end edge positions thereof coincide with the positions of both folded ends of the maximum width up ply or exceed the tire radial height by 20% or less of the tire cross-section height. Wrap and extend the cord at an angle of 35 ° or less to the tire equator,
The second reinforcing layer is disposed substantially symmetrically across the tire equatorial plane, and the width measured along the tire width direction is 35 to 55% of the tread width, and the cord is 25 ° or less with respect to the tire equatorial plane. Two-wheeled vehicle tire characterized by extending at an angle of The tire for a motorcycle according to claim 1, wherein the elastic foam has an apparent specific gravity of 0.1 to 0.2 and a rebound resilience of 50 to 80%. The tire for a motorcycle according to claim 1 or 2, wherein the cord constituting the first reinforcing layer and the second reinforcing layer is made of aromatic polyamide or steel. The tire for a motorcycle according to any one of claims 1 to 3, wherein the second reinforcing layer is positioned on the outer peripheral side of the crown portion of the first reinforcing layer. The tire for a motorcycle according to any one of claims 1 to 3, wherein the second reinforcing layer is located on the inner peripheral side of the crown portion of the carcass. The tire for a motorcycle according to any one of claims 1 to 5, wherein the cord constituting the carcass is made of nylon or polyethylene terephthalate.

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