JP7210210B2 - tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tire having a simplified bead portion structure.

As demand for environmental protection increases, tires are also required to be lighter in weight. As one method for reducing tire weight, a structure in which a bead filler (also called a stiffener) is omitted is known (see Patent Document 1).

JP 2008-149778 A

However, omitting the bead filler causes the following problems. Specifically, when the vehicle changes lanes at high speed (lane change), the bead portion in the vicinity of the rim flange particularly collapses greatly.

As a result, a delay in following the steering operation of the vehicle, an increase in roll of the vehicle, and a swing back after the lane change occur, thereby impairing the steering stability.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of such circumstances, and an object of the present invention is to provide a tire capable of ensuring sufficient steering stability even when the structure of the bead portion is simplified.

One aspect of the present invention includes a tread portion (tread portion 20) in contact with the road surface, a tire side portion (tire side portion 30) connected to the tread portion and located radially inward of the tread portion (tire side portion 30), and the tire side portion. A tire (pneumatic tire 10) including a bead portion (bead portion 60) connected to a portion and located radially inward of the tire side portion (bead portion 60), and a carcass (carcass 40) forming the frame of the tire. , the bead portion includes an inner bead core (inner bead core 210) provided on the inner side in the tire width direction, an outer bead core (outer bead core 220) provided on the outer side in the tire width direction, and at least one of the inner bead core and the outer bead core. and a bead filler sheet (bead filler sheet 400) provided radially outward along the carcass on the tire width direction outer side of the carcass, and the carcass is interposed between the inner bead core and the outer bead core. do.

According to the tire described above, sufficient steering stability can be ensured even when the structure of the bead portion is simplified.

FIG. 1 is a cross-sectional view of a pneumatic tire 10 along the tire width direction and the tire radial direction. FIG. 2 is an enlarged sectional view of the rim wheel 100 and the bead portion 60. FIG. FIG. 3 is a graph showing the evaluation test results of steering stability of a bead fillerless tire. FIG. 4 is an enlarged cross-sectional view of a rim wheel and bead portion according to another embodiment of the present invention. FIG. 5 is an enlarged cross-sectional view of a rim wheel and bead portion according to another embodiment of the present invention. FIG. 6 is a cross-sectional view along the tire width direction and tire radial direction of a pneumatic tire according to another embodiment of the present invention. FIG. 7 is an enlarged cross-sectional view of a rim wheel and bead portion according to another embodiment of the present invention. FIG. 8 is a cross-sectional view along the tire width direction and tire radial direction of a pneumatic tire according to another embodiment of the present invention.

Hereinafter, embodiments will be described based on the drawings. The same or similar reference numerals are given to the same functions and configurations, and the description thereof will be omitted as appropriate.

(1) Schematic Overall Configuration of Tire FIG. 1 is a partial cross-sectional view of a pneumatic tire 10 according to the present embodiment. Specifically, FIG. 1 is a cross-sectional view of the pneumatic tire 10 along the tire width direction and the tire radial direction. Note that FIG. 1 shows only one side with respect to the tire equator line CL. In addition, in FIG. 1, illustration of cross-sectional hatching is omitted (same below).

As shown in FIG. 1 , the pneumatic tire 10 includes a tread portion 20 , tire side portions 30 , carcass 40 , belt layers 50 and bead portions 60 .

The tread portion 20 is a portion that contacts a road surface (not shown). A pattern (not shown) is formed on the tread portion 20 according to the usage environment of the pneumatic tire 10 and the type of vehicle in which the pneumatic tire 10 is mounted.

The tire side portion 30 continues to the tread portion 20 and is positioned inside the tread portion 20 in the tire radial direction. The tire side portion 30 is a region from the tire width direction outer end of the tread portion 20 to the upper end of the bead portion 60 . The tire side portion 30 is sometimes called a sidewall or the like.

The carcass 40 forms the skeleton of the pneumatic tire 10 . The carcass 40 has a radial structure having carcass cords (not shown) radially arranged along the tire radial direction. However, the structure is not limited to the radial structure, and a bias structure in which the carcass cords are arranged so as to intersect in the tire radial direction may also be used.

The belt layer 50 is provided inside the tread portion 20 in the tire radial direction. The belt layer 50 includes a pair of intersecting belts in which cords intersect, and a reinforcing belt provided outside the intersecting belts in the tire radial direction. Reinforcement belts are also called caps and layers. Note that the belt layer 50 may include a reinforcing belt having a shape different from that of the cap and layer.

The bead portion 60 continues to the tire side portion 30 and is positioned inside the tire side portion 30 in the tire radial direction. The bead portion 60 has an annular shape, and the carcass 40 is inserted into the bead portion 60 .

In this way, the pneumatic tire 10 generally has a structure similar to that of tires mounted on general passenger cars (including minivans and SUVs (Sport Utility Vehicles)). Although details will be described later, in the pneumatic tire 10 , the bead portion 60 is not provided with a bead filler. The bead filler is also called a stiffener, and is made of a member such as rubber that is harder than the rubber of other parts. A bead filler is generally provided for the purpose of improving the rigidity of the bead portion 60 .

As described above, the pneumatic tire 10 is intended for passenger automobiles, and particularly preferably satisfies the following specifications.

・Tire width: 135 mm or more, 195 mm or less ・Rim diameter: 12 inches or more, 15 inches or less ・Aspect ratio: 65% or more, 80% or less ・Load index: 91 or less ・Air volume: 30 to 65 liters More specifically Preferably, the pneumatic tire 10 has a tire size as shown in Table 1. However, the tire size is not limited to this size, and other tire sizes may be used as long as the above specifications are satisfied.

A pneumatic tire 10 is assembled to a rim wheel 100 . Specifically, the bead portion 60 is engaged with a rim flange 110 (not shown in FIG. 1, see FIG. 2) formed at the radially outer end of the rim wheel 100. As shown in FIG.

The pneumatic tire 10 is a tire in which an internal space formed by being assembled to the rim wheel 100 is filled with air, but the gas filled in the internal space is not limited to air, and may be nitrogen gas. of inert gas may be used.

(2) Configuration of bead portion 60 Next, a specific configuration of the bead portion 60 will be described. FIG. 2 is an enlarged sectional view of the rim wheel 100 and the bead portion 60. FIG. Specifically, FIG. 2 is a sectional view of the rim wheel 100 and the bead portion 60 along the tire width direction and the tire radial direction.

As shown in FIG. 2 , the bead portion 60 has a bead core 205 and a bead filler sheet 400 .

The bead core 205 is an annular (ring)-shaped member extending in the tire circumferential direction, and is formed of a metal (steel) cord.

The bead portion 60, specifically, the bead core 205, is composed of an inner bead core 210 provided on the inner side in the tire width direction and an outer bead core 220 provided on the outer side in the tire width direction.

The inner bead core 210 is provided on the inner side of the carcass 40 in the tire width direction, and the outer bead core 220 is provided on the outer side of the carcass 40 in the tire width direction.

The inner bead core 210 is composed of two ring-shaped members each having a circular cross-sectional shape and having a plurality of cords twisted together. The two ring-shaped members are provided along the tire radial direction.

Similarly, the outer bead core 220 is also composed of two ring-shaped members having a circular cross-section and twisted with a plurality of cords. The two ring-shaped members are also provided along the tire radial direction.

Carcass 40 is interposed between inner bead core 210 and outer bead core 220 . In this embodiment, the tire radial inner end 40 a of the carcass 40 extends to the tire radial inner end 210 a of the inner bead core 210 and the tire radial inner end 220 a of the outer bead core 220 .

The inner bead core 210 and the outer bead core 220 thus sandwich the carcass 40 extending to the tire radial inner end 210a and the tire radial inner end 220a. Specifically, the inner bead core 210 contacts the tire width direction outer surface of the carcass 40 , and the outer bead core 220 contacts the tire width direction inner surface of the carcass 40 .

The bead filler sheet 400 is provided outside the carcass 40 in the tire width direction along the carcass 40 on the outside of the bead core 205 in the tire radial direction.

In addition, the tire radial direction outer end 401 of the bead filler sheet 400 is located in the tire radial direction inner side of the maximum width position Wmax (see FIG. 1) of the pneumatic tire 10 where the width along the tire width direction is maximum. should be located in In addition, the tire radially inner end 403 of the bead filler sheet 400 may be positioned radially outward of the tire radially inner and tire widthwise outer end of the bead core 205 in the tire radial direction.

That is, the bead filler sheet 400 is preferably provided between the end of the bead core 205 and the maximum width position Wmax of the pneumatic tire 10 in the tire radial direction.

In this embodiment, the bead filler sheet 400 is provided between a position facing the rim flange 110 in the tire radial direction and a maximum width position Wmax (see FIG. 1) where the width along the tire width direction is maximum. be done.

In the cross section along the tire radial direction and the tire width direction, the position on the tire equator line CL in the tread portion 20 is defined as a point A (see FIG. 1), and the tire radial direction of the bead portion 60 from the point A in the tire radial direction When the length to the inner end 60a is T (see FIG. 1), the length of the bead filler sheet 400 in the tire radial direction, that is, from the tire radial outer end 401 of the bead filler sheet 400 to the tire radial inner end 403 It is preferable that the length along the bead filler sheet 400 up to is 0.1T or more and 0.5T or less.

The thickness of the bead filler sheet 400 in a cross section along the tire radial direction and the tire width direction is preferably 0.2 mm or more and 2.5 mm or less. Moreover, the bead filler sheet 400 preferably has a 50% modulus (M50) of 3 MPa or more and 15 MPa or less.

The rim line 65 is a convex portion formed along the tire circumferential direction for checking whether the bead portion 60 is correctly attached to the rim wheel 100 . In the present embodiment, the rim line 65 is provided outside in the tire radial direction by about 6 mm from the tire radial direction outside end of the rim flange 110 .

(3) Functions and Effects Next, functions and effects of the pneumatic tire 10 will be described. Specifically, after explaining the steering stability of a tire (bead filler-less tire) in which a bead filler is not provided in the bead portion 60 like the pneumatic tire 10, the pneumatic tire 10 according to the present embodiment Actions and effects will be described.

(3.1) Steering Stability of Bead Fillerless Tire FIG. 3 is a graph showing evaluation test results of steering stability of a bead fillerless tire. Specifically, FIG. 3 shows evaluation test results of a general pneumatic tire provided with a bead filler (conventional example) and a bead fillerless tire (comparative example).

Note that the bead filler-less tire (comparative example) shown in FIG. It has the same configuration as

The conditions of the evaluation test, etc. are as follows.

・Installed vehicle: Front-wheel drive minivan ・Loading conditions: Equivalent to gross vehicle weight (capacity of passengers, maximum load capacity)
・Test method: Single lane change (severe)
Single lane change (severe) satisfies the following conditions.

・Approach speed: 100km/h
・Lateral G: 0.5 to 0.6
・Number of lane changes: 1 lane ・Lane change time: 2 seconds

FIG. 3 shows the steering angle of the steering wheel of the vehicle and the yaw angle generated in the vehicle for each of the conventional example and the comparative example.

First, focusing on the yaw angle in the first half of the lane change, in the comparative example, the yaw angle rises later than in the conventional example ((1) in the figure). Similar steering angles are given in the conventional example and the comparative example.

Next, when the lane change progresses and the vehicle reaches a certain yaw angle, the driver begins to return the steering wheel ((2) in the figure). Here, in the comparative example, the operation of the steering wheel, that is, the turning performance of the vehicle with respect to the steering angle is delayed, so the holding time at the steering angle is long. That is, in the comparative example, it takes a longer distance (time) than in the conventional example until the vehicle reaches a certain yaw angle.

In the latter half of the lane change, a steering (countersteer) angle in the direction opposite to the direction of the lane change is given in order to stay in the lane after the change. Since it takes a longer distance (time) than the conventional example to reach the corner, the countersteering angle is also large ((3) in the figure). As a result, in the comparative example, the roll amount of the vehicle is increased, and the vehicle swing back is also increased.

Considering the test results shown in Figure 3, it is important to improve the turning ability of the vehicle in the first half of the lane change in order to maintain steering stability when attempting to reduce tire weight by omitting the bead filler. is. As a result of examination including simulation, it was found that especially by suppressing the bead portion 60 from collapsing (protruding) in the vicinity of the rim flange 110, the steering stability can be maintained.

(3.2) Functions and Effects of Pneumatic Tire 10 According to the above-described embodiment, the following functions and effects are obtained. Specifically, in pneumatic tire 10 , bead core 205 of bead portion 60 is composed of inner bead core 210 and outer bead core 220 . Also, the carcass 40 is interposed between the inner bead core 210 and the outer bead core 220 . That is, the carcass 40 is not folded back via the bead core 205 like a general tire, and the bead portion 60 is not provided with a bead filler. Therefore, the gauge of the bead portion 60 can be made thinner.

Further, in the pneumatic tire 10 , the bead filler sheet 400 is provided along the carcass 40 on the outer side of the carcass 40 in the tire width direction. Therefore, the bead filler sheet 400 can support the load applied to the bead portion 60 and prevent the bead portion 60 from collapsing. That is, it is possible to ensure the steering stability of the vehicle on which the pneumatic tire 10 is mounted.

That is, according to the pneumatic tire 10, even when the structure of the bead portion 60 is simplified, sufficient steering stability can be ensured.

Furthermore, since the carcass 40 does not need to be folded back through the bead core 205, the manufacturing process can be simplified and the formation of air pockets in the folded portion can be avoided. Also, the degree of freedom in designing the carcass (carcass line) can be improved.

In the present embodiment, the tire radially inner end 40a of the carcass 40 extends at the tire radially inner end 210a of the inner bead core 210 or the tire radially inner end 220a of the outer bead core 220 . In particular, the inner bead core 210 and the outer bead core 220 sandwich the carcass 40 .

Therefore, the carcass 40 can be reliably interposed between the inner bead core 210 and the outer bead core 220, and the rigidity of the bead portion 60 can be improved. This can contribute to further improvement in steering stability of the vehicle.

In this embodiment, the bead filler sheet 400 is provided between a position facing the rim flange 110 in the tire radial direction and a maximum width position Wmax (see FIG. 1) where the width along the tire width direction is maximum. be done. Therefore, the bead filler sheet 400 can reliably support the load applied to the bead portion 60 and further effectively suppress the collapse of the bead portion 60 .

(4) Other Embodiments Although the content of the present invention has been described along with the examples, it should be understood that the present invention is not limited to these descriptions and that various modifications and improvements are possible. self-evident to the trader.

For example, the pneumatic tire 10 described above may be modified as follows. FIG. 4 is an enlarged cross-sectional view of a bead portion 60 of a pneumatic tire 10A according to a modification.

As shown in FIG. 4, in the pneumatic tire 10A, the bead core 205A is composed of the inner bead core 210 and the outer bead core 220A. The outer bead core 220A is composed of three ring-shaped members.

That is, like the bead core 205A, the inner bead core and the outer bead core do not necessarily have the same shape (symmetrical shape). Specifically, the number of ring-shaped members forming the inner bead core may differ from the number of ring-shaped members forming the outer bead core. Also, the number of ring-shaped members forming the inner bead core and the outer bead core is not limited to the illustrated number.

FIG. 5 is an enlarged cross-sectional view of a bead portion 60 of a pneumatic tire 10B according to another modification. As shown in FIG. 5, in the pneumatic tire 10B, a bead core 205B is composed of an inner bead core 210 and an outer bead core 220B. Outer bead core 220B is provided radially outside of inner bead core 210 .

That is, like the bead core 205B, the inner bead core and the outer bead core do not necessarily have to be provided at the same position in the tire radial direction. In the pneumatic tire 10B, the tire radially inner end 40a of the carcass 40 is positioned radially inward of the outer bead core 220B.

In addition, the tire radially inner end 40a of the carcass 40 may be located radially inward of the tire radially inner ends of the inner bead core and the outer bead core, or the inner bead core or the outer bead core may be positioned inward in the tire radial direction. It may be positioned radially inward of the radially inner end. Alternatively, the tire radially inner end 40a of the carcass 40 may be located outside the tire radially inner end of at least one of the inner bead core and the outer bead core.

The bead filler sheet 400 may be provided along the carcass 40 on the outside in the tire width direction of at least one of the inner bead core and the outer bead core in the tire radial direction. That is, the bead filler sheet 400 may be provided so as to overlap any bead core in the tire radial direction.

Further, as shown in FIG. 2, the bead portion 60 has an outer surface portion 61 that contacts the rim flange 110, and the radius of curvature R of the outer surface portion 61 may be 30 mm or more and 300 mm or less. In addition, it is more preferable that the curvature radius R is 50 mm or more and 200 mm or less.

The radius of curvature R is a circular arc passing through the position of the outer surface portion 61 with reference to the center located outside the bead portion 60 in the tire width direction in the cross section of the bead portion 60 along the tire width direction and the tire radial direction. is the radius. The curvature radius R is based on the position of the tire radial direction outer end 61 a of the outer surface portion 61 . In other words, it means the outermost position in the tire radial direction of the tire outer surface of the bead portion 60 that contacts the rim flange 110 . The radius of curvature R is based on the shape of the pneumatic tire 10 that is not attached to the rim wheel 100 and is not loaded.

The rubber gauge at the position of the tire radial outer end 61a, specifically, the thickness from the tire radial outer end 61a to the tire width direction outer end of the folded portion 42 (including the bead filler sheet 400) is 3.5 mm or more. , 9.5 mm.

When the outer surface portion 61 has a plurality of radii of curvature, that is, when the outer surface portion 61 is composed of a plurality of portions with different curvatures, the radius of curvature R is the length of the portion having each curvature. can be expressed as the average of the multiple radii of curvature according to .

Further, as shown in FIG. 6 , in the pneumatic tire 10X, the point A is the position on the tire equator line CL in the tread portion 20 . Point B is the tire maximum width position. The tire maximum width position is the maximum width position of the pneumatic tire 10 where the width along the tire width direction is maximum. L1 is an imaginary straight line passing through point A and parallel to the tire width direction. L2 is an imaginary straight line passing through point B and parallel to the tire width direction. L3 is an imaginary straight line parallel to the tire width direction passing through the middle of the imaginary straight line L1 and the imaginary straight line L2. A point C is an intersection point between the imaginary straight line L3 and the carcass 40 . Specifically, the point C is located on the carcass 40 on the outer side in the tire radial direction. L4 is an imaginary straight line passing through point C and parallel to the tire radial direction. L5 is an imaginary straight line that touches the carcass 40 at point C. In this embodiment, the angle θ1 formed by the virtual straight line L4 and the virtual straight line L5 is 30 degrees to 70 degrees. However, the angle θ1 is not limited to this. The angle θ1 may be 40-65 degrees.

Furthermore, as shown in FIG. 7, point D is the position of the tire radial direction outer end of the outer surface portion 61 . Specifically, point D is a separation point located on the outer surface of the pneumatic tire 10 where the outer surface portion 61 leaves contact with the rim flange 110 . L6 is an imaginary perpendicular line that passes through point D and intersects outer surface portion 61 at right angles. A point E is an intersection point between the virtual perpendicular line L6 and the folded portion 42 . L7 is an imaginary straight line that touches the folded portion 42 at point E. As shown in FIG. In the present embodiment, BL is a straight line (bead base line) passing through the rim diameter position of the rim wheel 100 and parallel to the tire width direction. In this embodiment, the angle θ2 formed by the imaginary straight line L7 and the bead baseline BL is 50 to 80 degrees. However, the angle θ2 is not limited to this. The angle θ2 may be 60 to 78 degrees, or may be 65 to 75 degrees.

Further, as shown in FIG. 8, the tire gauge thickness and the like may be set in the pneumatic tire 10Y. A point J shown in FIG. 8 is an outer end portion in the tire width direction of the belt 50c provided on the outermost side in the tire radial direction among the belt layers 50 . L10 is an imaginary straight line passing through point J and parallel to the tire radial direction. A point N is an intersection point between the virtual straight line L1 and the virtual straight line L2. X is the distance from point A to point N; Y is the distance from point N to point J; L11 is an imaginary perpendicular line that passes through point J and intersects the tire outer surface at right angles. Point K is the intersection of imaginary perpendicular L11 and the tire outer surface. The distance U from point J to point K is 2 to 10 mm. However, the distance U is not limited to this. The distance U may be 2.5-9 mm, or 3-8 mm. Also, the ratio Y/X between the distance Y and the distance X is 0.03 to 0.25. However, the ratio Y/X is not limited to this. The ratio Y/X may be between 0.05 and 0.20. The pneumatic tire 10 that satisfies the above requirements can ensure sufficient steering stability even when the structure of the bead portion 60 is simplified.

While embodiments of the present invention have been described above, the discussion and drawings forming part of this disclosure should not be construed as limiting the invention. Various alternative embodiments, implementations and operational techniques will become apparent to those skilled in the art from this disclosure.

10, 10A, 10B, 10X, 10Y Pneumatic tire 20 Tread portion 30 Tire side portion 40 Carcass 40a Tire radial inner end 41 Body portion 42 Folded portion 50 Belt layers 50a to c Belt 60 Bead portion 60a Tire radial inner end 61 Outer surface portion 61a Tire radially outer end 65 Rim line 100 Rim wheel 110 Rim flange 205, 205A, 205B Bead core 210 Inner bead core 210a Tire radially inner end 220, 220A, 220B Outer bead core 220a Tire radially inner end 400 Bead filler sheet 401 Tire radial direction outer end 403 Tire radial direction inner end

Claims (5)

A tread portion in contact with the road surface,
a tire side portion connected to the tread portion and positioned radially inward of the tread portion;
a bead portion connected to the tire side portion and positioned radially inward of the tire side portion;
A tire comprising a carcass forming the skeleton of the tire,
The bead portion
an inner bead core provided on the inner side in the tire width direction;
an outer bead core provided on the outer side in the tire width direction;
a bead filler sheet provided outside the carcass in the tire width direction along the carcass on at least one of the inner bead core and the outer bead core in the tire radial direction,
The carcass is interposed between the inner bead core and the outer bead core,
The thickness from the position of the tire radially outer end of the outer surface portion of the bead portion that contacts the rim flange to the tire width direction outer end of the carcass including the bead filler sheet is 3.5 mm or more and 9.5 mm. some tires. The tire according to claim 1, wherein the tire radially inner end of the carcass extends to the tire radially inner end of the inner bead core or the outer bead core. The tire according to claim 1 or 2, wherein the inner bead core and the outer bead core sandwich the carcass. The bead filler sheet is provided between a position facing a rim flange of a rim wheel mounted on the tire in the tire radial direction and a maximum width position of the tire where the width along the tire width direction is maximum. A tire according to any one of claims 1 to 3. The inner bead core and the outer bead core are composed of a plurality of ring-shaped members provided along the tire radial direction,
The tire according to any one of claims 1 to 4, wherein the number of ring-shaped members forming the outer bead core is greater than the number of ring-shaped members forming the inner bead core.

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