WO2013111576A1 - 空気入りタイヤ - Google Patents
空気入りタイヤ Download PDFInfo
- Publication number
- WO2013111576A1 WO2013111576A1 PCT/JP2013/000304 JP2013000304W WO2013111576A1 WO 2013111576 A1 WO2013111576 A1 WO 2013111576A1 JP 2013000304 W JP2013000304 W JP 2013000304W WO 2013111576 A1 WO2013111576 A1 WO 2013111576A1
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- WO
- WIPO (PCT)
- Prior art keywords
- tire
- radial direction
- tire radial
- carcass
- rim
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C13/00—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof
- B60C13/003—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof characterised by sidewall curvature
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C13/00—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C13/00—Tyre sidewalls; Protecting, decorating, marking, or the like, thereof
- B60C13/02—Arrangement of grooves or ribs
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C15/00—Tyre beads, e.g. ply turn-up or overlap
- B60C15/0009—Tyre beads, e.g. ply turn-up or overlap features of the carcass terminal portion
- B60C15/0027—Tyre beads, e.g. ply turn-up or overlap features of the carcass terminal portion with low ply turn-up, i.e. folded around the bead core and terminating at the bead core
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C15/00—Tyre beads, e.g. ply turn-up or overlap
- B60C15/02—Seating or securing beads on rims
- B60C15/024—Bead contour, e.g. lips, grooves, or ribs
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C15/00—Tyre beads, e.g. ply turn-up or overlap
- B60C15/02—Seating or securing beads on rims
- B60C15/024—Bead contour, e.g. lips, grooves, or ribs
- B60C15/0242—Bead contour, e.g. lips, grooves, or ribs with bead extensions located radially outside the rim flange position, e.g. rim flange protectors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C3/00—Tyres characterised by the transverse section
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C2200/00—Tyres specially adapted for particular applications
- B60C2200/06—Tyres specially adapted for particular applications for heavy duty vehicles
Definitions
- the present invention relates to a pneumatic tire that is reduced in weight by forming a concave portion by curling in a part of the side rubber near the bead portion.
- Patent Document 1 further includes one or more cord reinforcing layers outside the carcass.
- this measure may reduce the expected effect of reducing the weight of the tire. Therefore, it is important to maintain the steering stability at a high level while enjoying the weight reduction of the tire by providing the concave portion in the side rubber near the bead portion.
- an object of the present invention is to provide a pneumatic tire that achieves both weight reduction, steering stability and durability.
- the inventor has investigated the cause of hindrance to steering stability in a pneumatic tire having a recess in the side rubber near the bead portion. When the lateral rigidity of the tire is reduced and lateral force is applied to the tire. In addition, it has been found that the side wall portion starting from the concave portion is likely to fall down.
- the inventor defines the contour of the concave portion from the viewpoint of suppressing the falling of the sidewall portion as described above for a method for ensuring a high level of steering stability in a pneumatic tire having a concave portion in the side rubber near the bead portion.
- the knowledge that the lateral rigidity of the tire can be secured by setting the carcass line according to the curvature of the circle to be obtained was obtained. That is, if the carcass line is set according to the curvature of the recess, when the tire is filled with air, in the region from the bead portion to the sidewall portion, the air force inside the tire pushes the inner surface of the tire outward in the width direction.
- the rigidity increases from the bead portion to the sidewall portion, it has been found that the falling of the sidewall portion is suppressed, and the present invention has been completed.
- the gist of the present invention is as follows.
- a ply body portion that is formed by connecting a tread portion, a pair of sidewall portions, and a pair of bead portions, and extends in a toroid shape between a pair of bead cores embedded in the bead portion, and extends from the ply body portion
- a carcass comprising at least one ply wound around each bead core from the inner side to the outer side in the tire width direction, and further from the rim separation point to the tire maximum width position of the sidewall part
- the range up to the point where the peripheral length
- FIG. 1 is a schematic partial cross-sectional view in the tire width direction of a pneumatic tire according to the present invention, in which concave portions are defined by a plurality of arcs.
- FIG. 1 is a sectional view in the tire width direction of a pneumatic tire according to the present invention.
- FIG. 2 is a diagram showing a half part of a sectional view in the tire width direction of the pneumatic tire of the present invention shown in FIG.
- FIG. 3A is a diagram showing a half part of a sectional view in the tire width direction of the pneumatic tire of the present invention, in which concave portions are defined by a plurality of arcs.
- FIG. 3B is a schematic partial cross-sectional view in the tire width direction of the pneumatic tire of the present invention, in which concave portions are defined by a plurality of arcs.
- FIG. 1 is a sectional view in the tire width direction of a pneumatic tire according to the present invention.
- FIG. 2 is a diagram showing a half part of a sectional view in the tire width direction of the pneumatic tire of the present invention shown in FIG.
- FIG. 3A is a diagram showing a half part of a sectional view
- FIG. 4 is a view showing the resultant force of air applied from the tire inner side to the tire width direction outer side on the tire inner surface during internal pressure filling.
- FIG. 4 (a) shows the case of the pneumatic tire of the present invention.
- b) shows the case of a conventional pneumatic tire.
- FIG. 5 is a sectional view in the tire width direction of the pneumatic tire of the present invention.
- FIG. 1 is a view showing a cross section in the tire width direction of a pneumatic tire 1 of the present invention (hereinafter referred to as “tire”) in a non-rim assembled state in which the rim is not assembled.
- the tire 1 includes a tread portion 2, a pair of sidewall portions 3 and 3, and a pair of bead portions 4 and 4. Further, a ply body 6a extending in a toroidal shape between a pair of bead cores 5 and 5 embedded in the bead parts 4 and 4, and a tire width direction around each bead core 5 and 5 extending from the ply body 6a.
- the carcass 6 is provided with at least one ply including a winding portion 6b wound from the inside to the outside.
- the tire 1 further has a recess 7 in the tire radial direction region from the rim separation point F to the tire maximum width position P 1 of the sidewall portion 3.
- the rim separation point F means that the outer surface of the tire is a rim flange when the tire 1 is assembled to the applicable rim, the normal maximum internal pressure defined according to the tire size is filled, and no load is applied. The point that leaves the contact state. Applicable rims are industrial standards effective in the area where tires are produced and used.
- the tire maximum width position P 1 of the sidewall portion 3 refers to the outermost end in the tire width direction in the sidewall portion 3.
- the outer surface of the tire in the tire radial direction area between the rim separation point F and the tire maximum width position P 1, is provided to include the whole, towards the inside of the tire width direction concave It is formed by removing the meat so that That is, the concave portion is formed by at least one arc having a center on the outer side in the width direction from the outer surface of the sidewall portion and protruding inward in the width direction when viewed from the center.
- the shape of the recess 7 is defined by combining a single circular arc or a plurality of circular arcs having a center C on the outer side in the tire width direction with respect to the side rubber constituting the sidewall portion 3 with respect to the side rubber.
- FIG. 2 is a view showing a half portion of the tire 1 shown in FIG.
- the shape of the recess 7 is defined by forming an arc of a circle R 1 having a center C 1 and a radius of curvature r 1 of 50 mm.
- FIG. 1 is a view showing a half portion of the tire 1 shown in FIG.
- the radius of curvature r 2 has a center C 2 is a circle R 2 is 30mm arc and the radius of curvature r 3 has a center C 3 is the arc of a circle R 3 is 400mm
- the shape of the recess 7 is defined by forming two arcs.
- the circle R 2 having the center C 2 is inscribed in the circle R 3 having the center C 3 , whereby the shape of the recess 7 is defined by combining the arcs of a plurality of circles. Has been.
- the rim separation point F and the recesses 7 defined by the circles R 1 and R 2 are separated from each other, that is, the rim separation point F and the circle R 1 or There is also an outer surface between R 2 (the outer surface exists between the rim separation point F and the innermost end 7a in the tire radial direction of the recess 7 described below) Although the surface is drawn so as to bend toward the inner side of the tire, the outer surface is not included in the recess 7 in the present invention.
- the range from the innermost point 7a in the tire radial direction of the recess 7 to the point 8 mm away from the outer periphery in the tire radial direction along the periphery of the recess 7 along the peripheral length 8mm is defined as the innermost region in the tire radial direction of the recess.
- the curve defining the innermost region in the tire radial direction of the recess 7 is approximated by an arc by the least square method, it is important that the radius of curvature r of the arc is 5 to 80 mm in the tire of the present invention. .
- the curvature radius r is less than 5 mm, the curvature becomes too large and the compressive stress generated by the deflection of the tire tends to concentrate, and the surface rubber wrinkles may cause cracks, If the curvature radius r exceeds 80 mm, the curvature is small and it is difficult to sufficiently roll the side rubber in the region from the rim separation point F to the tire maximum width position P 1 .
- the center of curvature C means the center C 1 of the circle R 1 in the example shown in FIG. 2 , and the center C 2 of the circle R 2 in the example shown in FIG. 3A.
- the weight of the tire can be reduced, but on the other hand, the lateral rigidity of the tire is reduced, and the steering stability is reduced. Accompanied by a decline. That is, since the rigidity from the bead portion to the sidewall portion is reduced by forming the concave portion 7, the tire shape is likely to change particularly when lateral force is applied, and as a result, the balance in the tire width direction is lost. As a result, steering stability is reduced.
- the present invention provides a pneumatic tire having a concave portion in the side rubber near the bead portion, and the elevation angle ⁇ of the intersection A formed by the straight line q connecting the two intersections A and B and the reference line n measured from the center of curvature C is 40.
- the angle By setting the angle to ⁇ 60 °, the lateral rigidity of the tire is improved and good steering stability is achieved.
- the carcass ply body 6a extending from the bead portion 4 to the sidewall portion 3 is more tire-like than the carcass ply body 16a in the conventional pneumatic tire 11 shown in FIG. 4 (b).
- the rising angle from the rotation axis is large, and the curvature of the carcass line from the bead portion to the sidewall portion is small. That is, when the tire 1 is filled with air, the ratio of the component of the internal pressure in the region from the bead portion to the sidewall portion toward the outer side in the tire width direction is larger than before, and the air in the tire moves the inner surface of the tire. Since the resultant force pushing outward in the tire width direction increases, the side rigidity of the tire increases. As a result, even if the recess 7 is provided in the side rubber, it is possible to suppress the falling deformation of the sidewall portion 3 of the tire 1 and to ensure good steering stability as a whole.
- the elevation angle ⁇ of the intersection A formed by the straight line q connecting the two intersections A and B with the reference line n is set to 40 ° to 60 °. in the smaller the curvature of the tire inside surface in the region up to the tire maximum width position P 1 of the wall portion 3, and sufficiently large force to press the region in the width direction outside from the inside of the tire, since it is possible to increase the side rigidity is there.
- the elevation angle ⁇ is more than 60 °, the bead portion may generate heat, which may affect the durability.
- the elevation angle is more than 60 °, it is necessary to increase the radius of curvature of the carcass near the belt end in order to ensure a cross-sectional shape that is effective in suppressing the collapse of the sidewall portion when filling with internal pressure. This is because the contact portion with the belt is only in the vicinity of the center of the tire, and separation of the portion may occur due to repeated input of lateral force.
- the carcass 6 is wound around the bead cores 5 and 5 from the inner side to the outer side in the tire width direction and has winding portions 6b and 6b.
- the starting position of the arc drawn by the center of curvature C can be brought closer to the rim separation point F, which greatly contributes to reducing the use of rubber and pulling the carcass 6. Omission can be made difficult.
- the elevation angle ⁇ at the intersection A where the straight line q forms the reference line n is more preferably 50 to 60 °.
- the tire width direction maximum width W 6 of the carcass 6 is 115-135% of the bead heel distance W 8 between the pair of bead heel 8,8, tire width direction outermost end of the carcass P 2 is a position in the tire radial direction closer to the outer side in the tire radial direction by 45% of the carcass height H from the innermost end P 3 in the tire radial direction of the carcass 6, and a carcass height from the innermost end P 3 in the tire radial direction in the carcass 6. It is preferable to be in the tire radial direction region S between 60% of the H and the tire radial direction position on the outer side in the tire radial direction.
- the tire width direction maximum width W 6 of the carcass 6, ply body 6a is that the tire width direction distance between tire width 6a direction outermost end P 2, P 2.
- the bead heel distance W8 is a distance in the tire width direction between the bead heels 8 and 8 of the pair of bead portions 4 and 4, and corresponds to the width of the applicable rim described in the standard such as JATMA. To do.
- FIG. 5 shows an example in which the carcass 6 is composed of a single ply, but the dimensions defined by the carcass are measured from the cord center of the carcass ply main body unless otherwise specified. .
- the above-mentioned definition is that the cord center line of the carcass ply main body portion on the innermost side in the tire width direction and the outermost side in the tire width direction are The dimension on the virtual carcass center line, which is a line passing through the center in the width direction with the cord center line of the ply main body portion of the carcass, is referred to.
- the flatness of the pneumatic tire 1 according to the present invention is preferably 60 to 80. Further, by assembling the tire to the application rim, in a state filled with maximum air pressure, the contour of the carcass 6a in the tire width direction outermost end P 2 is the radius of curvature r 4 is defined by an arc of 50 ⁇ 120 mm Is preferred.
- the thickness x of the sidewall portion 3 is constant.
- the thickness x of 3 is preferably 3.0 to 5.0 mm.
- the thickness x of the sidewall portion means the shortest distance from the cord center of the ply main body portion 6a in the sidewall portion 3 to the tire outer surface.
- the ratio of the component of the internal pressure toward the outer side in the tire width direction is larger than that of the conventional tire. Therefore, by setting the sidewall portion in the region S to have a constant thickness, it is possible to uniformly receive the outward force in the tire width direction, and as a result, better steering stability can be realized.
- the thickness x of the sidewall portion 3 in the region S is 3.0 to 5.0 mm in order to stably receive the force due to the internal pressure and in consideration of damage from the outside and a decrease in durability due to heat generation. It is preferable.
- the innermost end 7a in the tire radial direction of the recess 7 is in a tire radial region between a tire radial position at the rim separation point F and a tire radial position closer to the outer side in the tire radial direction by 10 mm from the rim separation point F. It is preferable that it exists in.
- the amount of rubber used around the bead can be sufficiently reduced, so that weight reduction can be achieved while maintaining appropriate tire rigidity. Because it can.
- the tire size is 275 / 80R22.5, and as shown in FIG. 1, the tire has a recess in the region from the rim separation point to the tire maximum width position, and the elevation angle at the intersection A is 40 to 60 °.
- Inventive tires 1 to 3 were prototyped. Each specification is as shown in Table 1.
- comparative tires 1 to 6 having a recess as in the invention example tire 1 and having the specifications shown in Table 1 were also prototyped.
- the tire weight reduction amount (kg) is a reduction amount from a tire having no recess, that is, the rubber weight (kg) of the recess.
- Each of the inventive tires 1 to 3 and the comparative tires 1 to 6 is assembled to a rim having a rim size of 8.25 ⁇ 22.5 and a rim width of 8.25 inches (21.0 cm), and the internal pressure is set to 900 kPa.
- the steering stability and durability were evaluated by performing the following tests.
- ⁇ Steering stability evaluation> This was performed by comprehensively evaluating the braking performance, acceleration performance, straight travel performance, and cornering performance of the test driver when the vehicle with the above tires was run on a test course in fine weather.
- the evaluation results are as shown in Table 2.
- the evaluation in Table 2 is expressed as an index with the result of Comparative Example Tire 1 being 100, and the larger the value, the better the steering stability.
- ⁇ Durability evaluation> A tire that has changed over time by being filled with oxygen in the tire (oxygen concentration of 90% or more) and assembled to a rim of the above size for 60 days in a thermostatic chamber at 60 ° C. was mounted on a drum testing machine.
- a drum tester having a diameter of 1.7 m with a slip angle of 110% (3575 kg) of the standard load by JATMA and a side force of 0.3 G (975 kg) at a test speed of 60 km / h.
- the results of the durability evaluation shown in Table 1 are expressed as an index by measuring the distance traveled until the cracks are generated and propagated from the recesses in the process of repeated rolling.
- the evaluation in Table 2 is based on the result of Comparative Example Tire 1 being 100, and the larger the value, the better the durability.
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Description
一方、特許文献1では、ゴム使用量の多いビード部近傍のサイドゴムにつき、そのタイヤの外側面を抉って凹部を設けることによって、凹部の体積分のゴム量を削減し、タイヤ重量を低減することが提案されている。
従って、ビード部近傍のサイドゴムに凹部を設けることによるタイヤの軽量化を享受しつつ、同時に操縦安定性を高い次元で維持することが重要である。
トレッド部と、一対のサイドウォール部と、一対のビード部とを連ねて成り、前記ビード部に埋設された一対のビードコア間にトロイド状に延在するプライ本体部と、該プライ本体部から延びて各ビードコアの周りをタイヤ幅方向内側から外側に巻き回される巻き付け部とからなる少なくとも一枚のプライによるカーカスを備え、さらに、リム離反点から前記サイドウォール部のタイヤ最大幅位置までのタイヤ外表面にタイヤ幅方向内側に凹となる凹部を有する空気入りタイヤであって、
リムに組み付けていない非リム組状態の、タイヤ幅方向断面において、前記凹部を画定する前記タイヤ外表面のタイヤ径方向最内側点から、タイヤ径方向外側に、前記タイヤ外表面のペリフェリに沿ってペリフェリ長さ8mm離間した点までの範囲をタイヤ径方向最内側域とするとき、該タイヤ径方向最内側域をなす曲線を最小二乗法により円弧で近似した際の該円弧の曲率中心Cから前記プライ本体部のタイヤ幅方向外側へ凸となる部分へ引いた法線と該プライ本体部との交点A、そして前記曲率中心Cを通ってタイヤ回転軸と平行な基準線と前記プライ本体部との交点B、の二点を結ぶ直線が前記基準線と成す、交点Aの仰角が40~60°であり、
前記円弧の曲率半径は5~80mmであることを特徴とする空気入りタイヤ。
タイヤ1は、トレッド部2と、一対のサイドウォール部3、3と、一対のビード部4、4を備えている。また、ビード部4、4に埋設された一対のビードコア5、5間にトロイド状に延在するプライ本体部6aと、該プライ本体部6aから延びて各ビードコア5、5の周りをタイヤ幅方向内側から外側に巻き回される巻き付け部6bとからなる、少なくとも一枚のプライによるカーカス6を備えている。
図2は、図1に示したタイヤ1の半部を示す図である。この例では、中心C1を有し、曲率半径r1が50mmである円R1の円弧を形成することによって、凹部7の形状が画定されている。
一方、図3Aに示す例では、中心C2を有し曲率半径r2が30mmである円R2の円弧と、中心C3を有し曲率半径r3が400mmである円R3の円弧の2つの円弧を形成することによって、凹部7の形状が画定されている。
また、図3Bに示す例では、中心C2を有する円R2が、中心C3を有る円R3に内接し、これにより、凹部7の形状は、複数の円の円弧を組み合わせることによって画定されている。
曲率半径rを5mm未満とすると、曲率が大きくなり過ぎて、タイヤの撓みにより発生する圧縮応力が集中し易くなり、表面のゴムのシワはクラックの発生を引き起こすおそれがあるからであり、一方で、曲率半径rを80mm超とすると、曲率が小さく、リム離反点Fからタイヤ最大幅位置P1までの領域内においてサイドゴムを十分に抉ることが難しいからである。
ここで、上記曲率中心Cとは、図2に示す例では、円R1の中心C1のことを、図3Aに示す例では、円R2の中心C2のことを言う。
そこで本発明は、ビード部近傍のサイドゴムに凹部を有する空気入りタイヤにおいて、曲率中心Cから計測した、二点の交点A、Bを結ぶ直線qが基準線nと成す交点Aの仰角αを40~60°に設定することにより、タイヤの横剛性を向上させて、良好な操縦安定性を実現しようとするものである。図4(a)に示すように、ビード部4からサイドウォール部3に延びるカーカスのプライ本体6aは、図4(b)に示す従来の空気入りタイヤ11におけるカーカスのプライ本体16aよりも、タイヤ回転軸からの立ち上がり角度が大きく、ビード部からサイドウォール部にかけてのカーカスラインの曲率が小さくなっている。つまり、タイヤ1に空気を充填した際、ビード部からサイドウォール部にかけての領域での内圧の、タイヤ幅方向外側向きの成分の割合が従来よりも多くなり、タイヤ内の空気が、タイヤ内面をタイヤ幅方向外側に押す合力が増加するため、タイヤのサイド剛性が高まる。その結果、サイドゴムに凹部7を設けてもなお、タイヤ1のサイドウォール部3の倒れ込み変形を抑制し、総じて良好な操縦安定性を確保することが可能となる。
そして、仰角αを決定するにあたり、上記曲率中心Cを基準にすることが肝要である。軽量化のためにビード部に凹部を設けた場合、サイドウォール部の倒れ込みは、交点Aを含むビード部分が、交点Bを中心として曲率中心Cに向かうように変形するからである。
このようにカーカス6をビードコア5の周りに巻き付けることで、曲率中心Cによって描かれる円弧の開始位置をリム離反点Fに近づけることができ、ゴムの使用低減に大きく寄与し、かつカーカス6の引き抜けを生じ難くすることができる。
上記数値範囲にすることで、タイヤ内の空気が、リム離反点Fからサイドウォール部3のタイヤ最大幅位置P1までの領域をタイヤ内側から幅方向外側に押す合力が十分に大きくなるため、横剛性を向上することができる。その結果、さらに良好な操縦安定性を実現することができるからである。
W6がW8の135%超であると、ビード部のリムフランジへの乗上げが大きくなり、ビード耐久性が悪化するおそれがあり、W6がW8の115%未満だとタイヤのエアボリュームが減り、タイヤとしての負荷能力が減ることに繋がりタイヤ全ての耐久性に問題が生じるおそれがあるからである。
ここで、カーカス6のタイヤ幅方向最大幅W6とは、プライ本体6a、6aのタイヤ幅方向最外側端P2、P2間のタイヤ幅方向距離のことである。また、ビードヒール間距離W8とは、一対のビード部4、4のビードヒール8、8間の、タイヤ幅方向距離のことであり、前述のJATMA等の規格に記載された適用リムの幅に相当する。また、カーカス高さHとは、タイヤ径方向最内側端P3を通るタイヤ回転軸に平行な直線及びタイヤ径方向最外側端P4を通るタイヤ回転軸に平行な直線の間の、タイヤ径方向距離のことである。
また、図示はしていないが、カーカス6が複数枚のプライからなる場合には、上記の規定は、最もタイヤ幅方向内側のカーカスのプライ本体部のコード中心線と、最もタイヤ幅方向外側のカーカスのプライ本体部のコード中心線との幅方向中央を通る線である、仮想カーカス中心線上の寸法を言うものとする。
ここで、サイドウォール部の厚さxとは、サイドウォール部3におけるプライ本体部6aのコード中心から、タイヤ外表面までの最短距離のことを言う。具体的に図5を用いて説明すれば、カーカスのプライ本体部6aのタイヤ幅方向最外側端P2から、プライ本体部6aの法線とタイヤ外表面との交点まで、ここではタイヤ最大幅位置P1までの距離のことである。
本発明のタイヤでは、図4(a)を用いて説明したように、内圧のタイヤ幅方向外側向きの成分の割合が従来のタイヤよりも多くなる。従って、領域Sでのサイドウォール部を一定の厚みにすることで、タイヤ幅方向外側向きの力を均等に受けることができ、その結果、より良好な操縦安定性を実現することが可能となる。なお、内圧による力を安定的に受けるため及び外部からの損傷、発熱による耐久性の低下を考慮した場合、領域Sでのサイドウォール部3の厚さxは3.0~5.0mmであることが好ましい。
リム離反点Fからタイヤ径方向外側に0~10mmの範囲内にすることで、ビード周りのゴム使用量を充分に低減することができるため、適度なタイヤ剛性を維持しつつ、軽量化を図ることができるからである。
また、発明例タイヤ1と同様に凹部を有し、表1に示す諸元を有する比較例タイヤ1~6も試作した。なお、タイヤ重量低減量(kg)とは、凹部を有していないタイヤからの低減量であり、すなわち凹部のゴム重量(kg)を表している。
上記のタイヤを装着した車両によって晴天時のテストコースを走行した際の、テストドライバーによる制動性、加速性、直進性及びコーナリング性を総合的にフィーリング評価することによって行った。評価結果は、表2に示す通りである。表2中の評価は、比較例タイヤ1の結果を100として指数で表したものであり、数値が大きいほど操縦安定性が良好であることを示す。
タイヤ内に酸素充填(酸素濃度90%以上)し上記サイズのリムに組付けた状態で、60℃の恒温庫にて60日間保管することにより経年変化したタイヤをドラム試験機上に取り付けた。そして、JATMAによる規格荷重の110%(3575kg)、試験速度60km/hにて、サイドフォースが0.3G(975kg)となるようにスリップ角を付与した状態で、直径1.7mのドラム試験機上を繰り返し転動させた。表1に示す耐久性評価の結果は、繰り返し転動の過程において、凹部からの亀裂の発生及び進展に至るまでの走行距離を計測することにより、これを指数化して表したものである。表2中の評価は、比較例タイヤ1の結果を100としたものであり、数値が大きいほど、耐久性が良いことを示している。
2 トレッド部
3 サイドウォール部
4 ビード部
5 ビードコア
6 カーカス
6a プライ本体部
6b 巻き付け部
7 凹部
7a 凹部7のタイヤ径方向最内側端
8 ビードヒール
A 法線mとプライ本体部6aとの交点
B 基準線nとプライ本体部6aとの交点
C 曲率中心
F リム離反点
W6 カーカス6のタイヤ幅方向最大幅
W8 ビードヒール8のタイヤ幅方向幅
H カーカス高さ
r 曲率半径
m 曲率中心Cから、プライ本体部6aのタイヤ幅方向外側へ凸となる部分へ引いた法線
n 曲率中心Cを通ってタイヤ回転軸と平行な基準線
q 二点の交点A、Bを結ぶ直線
α 直線qと基準線nとが成す交点Aの仰角
Claims (4)
- トレッド部と、一対のサイドウォール部と、一対のビード部とを連ねて成り、前記ビード部に埋設された一対のビードコア間にトロイド状に延在するプライ本体部と、該プライ本体部から延びて各ビードコアの周りをタイヤ幅方向内側から外側に巻き回される巻き付け部とからなる少なくとも一枚のプライによるカーカスを備え、さらに、リム離反点から前記サイドウォール部のタイヤ最大幅位置までのタイヤ外表面にタイヤ幅方向内側に凹となる凹部を有する空気入りタイヤであって、
リムに組み付けていない非リム組状態の、タイヤ幅方向断面において、前記凹部を画定する前記タイヤ外表面のタイヤ径方向最内側点から、タイヤ径方向外側に、前記タイヤ外表面のペリフェリに沿ってペリフェリ長さ8mm離間した点までの範囲をタイヤ径方向最内側域とするとき、該タイヤ径方向最内側域をなす曲線を最小二乗法により円弧で近似した際の該円弧の曲率中心Cから前記プライ本体部のタイヤ幅方向外側へ凸となる部分へ引いた法線と該プライ本体部との交点A、そして前記曲率中心Cを通ってタイヤ回転軸と平行な基準線と前記プライ本体部との交点B、の二点を結ぶ直線が前記基準線と成す、交点Aの仰角が40~60°であり、
前記円弧の曲率半径は5~80mmであることを特徴とする空気入りタイヤ。 - 前記非リム組状態において、前記カーカスのタイヤ幅方向最大幅は、一対のビードヒール間距離の115~135%であり、前記カーカスのタイヤ幅方向最外側端は、前記カーカスのタイヤ径方向最内側端からカーカス高さの45%タイヤ径方向外側寄りのタイヤ径方向位置と、前記カーカスのタイヤ径方向最内側端からカーカス高さの60%タイヤ径方向外側寄りのタイヤ径方向位置との間のタイヤ径方向領域内に在る、請求項1に記載の空気入りタイヤ。
- 前記非リム組状態において、前記凹部のタイヤ径方向最内側端は、前記リム離反点のタイヤ径方向位置と、該リム離反点から10mmタイヤ径方向外側寄りのタイヤ径方向位置との間のタイヤ径方向領域内に在る、請求項1又は2に記載の空気入りタイヤ。
- 前記サイドウォール部におけるプライ本体部のコード中心からタイヤ外表面までの最短距離をサイドウォール部の厚さとしたとき、前記非リム組状態における、前記カーカスのタイヤ径方向最内側端から前記カーカス高さの45%タイヤ径方向外側寄りのタイヤ径方向位置と、前記カーカスのタイヤ径方向最内側端から前記カーカス高さの60%タイヤ径方向外側寄りのタイヤ径方向位置との間のタイヤ径方向領域において、前記サイドウォール部の厚さは一定であり、該領域内において、前記サイドウォール部の厚さは3.0~5.0mmである、請求項1~3のいずれか一項に記載の空気入りタイヤ。
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| US14/372,305 US9120352B2 (en) | 2012-01-24 | 2013-01-23 | Pneumatic tire |
| EP13740906.6A EP2808183B1 (en) | 2012-01-24 | 2013-01-23 | Pneumatic tire |
| JP2013555199A JP5576994B2 (ja) | 2012-01-24 | 2013-01-23 | 空気入りタイヤ |
| CN201380006303.8A CN104066600B (zh) | 2012-01-24 | 2013-01-23 | 充气轮胎 |
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| JP2012-012282 | 2012-05-25 |
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| Application Number | Title | Priority Date | Filing Date |
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| PCT/JP2013/000304 Ceased WO2013111576A1 (ja) | 2012-01-24 | 2013-01-23 | 空気入りタイヤ |
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| Country | Link |
|---|---|
| US (1) | US9120352B2 (ja) |
| EP (1) | EP2808183B1 (ja) |
| JP (1) | JP5576994B2 (ja) |
| CN (1) | CN104066600B (ja) |
| WO (1) | WO2013111576A1 (ja) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015097925A1 (ja) * | 2013-12-27 | 2015-07-02 | 株式会社ブリヂストン | 空気入りタイヤ |
| WO2018163577A1 (ja) * | 2017-03-10 | 2018-09-13 | 横浜ゴム株式会社 | 空気入りタイヤ及びその製造方法 |
| CN115135515A (zh) * | 2020-02-19 | 2022-09-30 | 米其林集团总公司 | 具有低胎侧高度的轮胎 |
| EP4249288A1 (en) | 2022-03-23 | 2023-09-27 | Sumitomo Rubber Industries, Ltd. | Heavy duty tire and production method for heavy duty tire |
| WO2023188604A1 (ja) * | 2022-03-29 | 2023-10-05 | 横浜ゴム株式会社 | 空気入りタイヤ |
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| WO2013128853A1 (ja) * | 2012-03-02 | 2013-09-06 | 株式会社ブリヂストン | 空気入りタイヤ |
| CN104354540A (zh) * | 2014-10-13 | 2015-02-18 | 王友善 | 一种全钢丝三角胶外置的无内胎子午线轮胎 |
| JP6935365B2 (ja) * | 2018-06-21 | 2021-09-15 | 株式会社ブリヂストン | 建設車両用タイヤ |
| JP7081999B2 (ja) * | 2018-06-29 | 2022-06-07 | Toyo Tire株式会社 | 空気入りタイヤ |
| FR3096931B1 (fr) * | 2019-06-06 | 2021-05-21 | Michelin & Cie | Pneumatique comportant des flancs optimises et une armature de sommet constituee de deux couches de sommet de travail et d’une couche d’elements de renforcement circonferentiels |
| US12194784B2 (en) | 2020-11-18 | 2025-01-14 | The Goodyear Tire & Rubber Company | Radial tire |
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Also Published As
| Publication number | Publication date |
|---|---|
| EP2808183B1 (en) | 2016-11-16 |
| US20140345770A1 (en) | 2014-11-27 |
| CN104066600B (zh) | 2016-09-14 |
| EP2808183A4 (en) | 2015-08-26 |
| JPWO2013111576A1 (ja) | 2015-05-11 |
| CN104066600A (zh) | 2014-09-24 |
| US9120352B2 (en) | 2015-09-01 |
| JP5576994B2 (ja) | 2014-08-20 |
| EP2808183A1 (en) | 2014-12-03 |
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