JP2012076690A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire improved in high-speed durability thereof in a structure, in which a wound-up end of a carcass layer extends to a lower layer of a belt layer.SOLUTION: In this pneumatic tire 1, the carcass layer 4 has a single-layer structure, and the wound-up end 42 of the carcass layer 4 is disposed under the belt layer, extending to the inside in the tire cross direction of the belt layer 5 than the outside in the tire cross direction thereof. This pneumatic tire 1 includes a carcass reinforcing material 8 disposed between the wound-up end 42 of the carcass layer 4 and the belt layer 5 to cover the wound-up end 42 of the carcass layer 4 from the outside in the tire radial direction.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve high-speed durability performance of a tire in a structure in which a rolled-up end portion of a carcass layer extends to a lower layer of a belt layer.

  In recent years, pneumatic tires have reduced tire rolling resistance by reducing tire weight by making a reply (reducing the weight of the carcass layer) because of the need for environmental contributions such as global warming countermeasures. As such a reply structure, the carcass layer has a single-layer structure, and the rolled-up end portion of the carcass layer extends to the inner side in the tire width direction from the end portion on the outer side in the tire width direction of the belt layer and is disposed in the lower layer of the belt layer. The structure is adopted. As a conventional pneumatic tire employing such a structure, a technique described in Patent Document 1 is known.

JP 2008-302775 A

  Here, in the pneumatic tire having the above-described resply structure, there is a problem that separation is likely to occur at the rolled-up end portion of the carcass layer.

  Accordingly, the present invention has been made in view of the above, and provides a pneumatic tire capable of improving the high-speed durability performance of the tire in a structure in which the winding end portion of the carcass layer extends to the lower layer of the belt layer. With the goal.

  In order to achieve the above object, in the pneumatic tire according to the present invention, at least one rolled-up end portion of the carcass layer extends to the inner side in the tire width direction from the end portion on the outer side in the tire width direction of the belt layer. A pneumatic tire disposed in a lower layer, comprising a carcass reinforcing material disposed between a winding end portion of the carcass layer and the belt layer and covering the winding end portion of the carcass layer from the outer side in the tire radial direction. It is characterized by.

  In this pneumatic tire, since the carcass reinforcing material holds the rolled-up end portion of the carcass layer, peeling of the rolled-up end portion is effectively prevented. Thereby, there exists an advantage which the high-speed durability performance of a tire improves.

  In the pneumatic tire according to the present invention, the carcass reinforcing material is made of an organic fiber cord, and an angle θ formed by a fiber direction of the carcass reinforcing material and a tire circumferential direction is −15 [deg] ≦ θ ≦ 15 [. deg].

  In this pneumatic tire, when the fiber direction of the carcass reinforcing material substantially coincides with the tire circumferential direction (0 degree direction), the holding force (tag effect) of the end portion of the carcass layer by the carcass reinforcing material is appropriately ensured. . Thereby, there exists an advantage which the high-speed durability performance of a tire improves appropriately.

  In the pneumatic tire according to the present invention, the width H of the carcass reinforcing material is 1.0 ≦ H / W ≦ 4.0 with respect to the wrap width W between the rolled-up end portion of the carcass layer and the belt layer. Is in range.

  In this pneumatic tire, the ratio H / W of the width H of the carcass reinforcing material to the lap width W is optimized, so that the holding force of the rolled-up end portion of the carcass layer by the carcass reinforcing material is appropriately ensured. Thereby, there exists an advantage which the high-speed durability performance of a tire improves appropriately.

  In the pneumatic tire according to the present invention, the thickness t of the carcass reinforcing material is in the range of 0.5 [mm] ≦ t ≦ 1.5 [mm].

  In this pneumatic tire, the holding force of the winding end of the carcass layer by the carcass reinforcing material is appropriately ensured by optimizing the width H of the carcass reinforcing material. Thereby, there exists an advantage which the high-speed durability performance of a tire improves appropriately.

  Further, in the pneumatic tire according to the present invention, the end portion of the carcass reinforcing member on the outer side in the tire width direction and the end portion of the constituent member of the belt layer are mutually in the tire width direction in a sectional view in the tire meridian direction. In different positions.

  In this pneumatic tire, stress concentration at the end portion of the member is alleviated, and separation of the tread rubber is suppressed. Thereby, there exists an advantage which the high-speed durability performance of a tire improves further.

  The pneumatic tire according to the present invention is applied to a tire having an aspect ratio of 40 or more.

  There is an advantage that the effect of improving the high-speed durability performance of the tire can be obtained more remarkably by applying the tire having a flatness ratio of 40 or more.

  In the pneumatic tire according to the present invention, since the carcass reinforcing material holds the rolled-up end portion of the carcass layer, peeling of the rolled-up end portion is effectively prevented. Thereby, there exists an advantage which the high-speed durability performance of a tire improves.

FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a main part of the pneumatic tire shown in FIG. FIG. 3 is an explanatory diagram showing a positional relationship between the carcass reinforcing layer and the belt layer. FIG. 4 is an explanatory diagram showing a positional relationship between the carcass reinforcing layer and the belt layer. FIG. 5 is an explanatory diagram showing a positional relationship between the carcass reinforcing layer and the belt layer. FIG. 6 is a table showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Pneumatic tire]
The pneumatic tire 1 includes a bead core 2, a bead filler 3, a carcass layer 4, a belt layer 5, a tread rubber 6, and a sidewall rubber 7 (see FIG. 1). The bead core 2 has an annular structure and is configured as a pair of left and right. The bead filler 3 is disposed on the outer periphery of the bead core 2 in the tire radial direction and reinforces the bead portion of the tire.

  The carcass layer 4 is made of a rolled material in which organic fiber cords are arranged, and is stretched between the left and right bead cores 2 and 2 in a toroidal shape to form a tire skeleton. Further, both end portions 42, 42 of the carcass layer 4 are wound up outward in the tire width direction so as to wrap the bead filler 3, and extend to the inner side in the tire width direction from the end portion of the belt layer 5 on the outer side in the tire width direction. . Further, both end portions 42, 42 of the carcass layer 4 are positioned below the belt layer 5 (inner side in the tire radial direction) and are sandwiched and locked between the belt layer 5 and the main body portion 41 of the carcass layer 4. . In this embodiment, the end portion 42 of the carcass layer 4 is called a rolled-up end portion.

  The belt layer 5 includes belt members 51 and 52 in which steel fiber cords are arranged, and is disposed on the outer periphery of the carcass layer 4 in the tire radial direction. The belt layer 5 is configured by laminating a pair of belt members 51 and 52 with their fiber directions intersecting each other (cross-ply structure). Further, belt cover layers 53 and 54 for protecting the belt materials 51 and 52 are disposed on the outer circumferences of the belt materials 51 and 52 in the tire radial direction.

  The tread rubber 6 is disposed on the outer circumference in the tire radial direction of the carcass layer 4 and the belt layer 5 to constitute a tread portion of the tire. The sidewall rubber 7 is configured as a pair of left and right sides, and is disposed on the outer side in the tire width direction of the carcass layer 4 to constitute a sidewall portion of the tire.

[Carcass reinforcement]
The pneumatic tire 1 has a carcass reinforcing material 8 (see FIGS. 1 and 2). The carcass reinforcing member 8 is a member that is disposed between the winding end portion 42 of the carcass layer 4 and the belt layer 5 and covers the winding end portion 42 of the carcass layer 4 from the outer side in the tire radial direction.

  For example, in this embodiment, the carcass reinforcing material 8 is made of an organic fiber cord such as nylon cord or aramid (not shown). For example, a nylon cord of 940 [dtex] or an aramid of 940 [dtex] to 1100 [dtex] is employed. Here, the carcass reinforcing material 8 may be formed by spirally winding an organic fiber cord in the tire circumferential direction (strip winding method), or may be formed of a rolled material in which organic fiber cords are arranged. good. At this time, the thickness t (not shown) of the carcass reinforcing material 8 is set within a range of 0.5 [mm] ≦ t ≦ 1.5 [mm]. Further, the width H of the carcass reinforcing material 8 is preferably in the range of 1.0 ≦ H / W ≦ 4.0 with respect to the wrap width W between the rolled-up end portion 42 of the carcass layer 4 and the belt layer 5 ( (See FIG. 3).

  Moreover, it is preferable that the fiber direction of the carcass reinforcing material 8 substantially coincides with the tire circumferential direction (0-degree direction) (not shown). Specifically, the angle θ formed by the fiber direction of the carcass reinforcing material 8 and the tire circumferential direction is preferably in the range of −15 [deg] ≦ θ ≦ 15 [deg], and −10 [deg] ≦ θ. More preferably, it is within the range of ≦ 10 [deg]. Thereby, the holding force (tag effect) of the winding end part 42 of the carcass layer 4 by the carcass reinforcing material 8 is ensured appropriately.

  The carcass reinforcing material 8 preferably has a single-layer structure (see FIGS. 1 and 2). Such a configuration is preferable in that an increase in tire weight due to the carcass reinforcing material is suppressed. However, the present invention is not limited to this, and the carcass reinforcing material 8 may have a multilayer structure (not shown). For example, the carcass reinforcing material 8 may be formed by wrapping organic fiber cords in the tire circumferential direction in a multiple and spiral manner, or by laminating a plurality of rolled materials in which organic fiber cords are arranged. Also good. Such a configuration is preferable in that the holding force (tag effect) of the winding end portion 42 of the carcass layer 4 by the carcass reinforcing material 8 is improved.

  Further, the left and right winding end portions 42 of the carcass layer 4 are located on the inner side in the tire radial direction from the end portions of the belt layer 5, and the carcass reinforcing material 8 is disposed with respect to these winding end portions 42. Is preferred. However, the present invention is not limited to this, and in the configuration in which only one winding end 42 is positioned on the inner side in the tire radial direction than the end of the belt layer 5, it is sufficient that the carcass reinforcing material 8 is disposed only on the winding end 42. .

  Moreover, it is preferable that the center position of the carcass reinforcing member 8 and the winding end portion 42 of the carcass layer 4 are substantially in the same position with respect to the tire width direction in a sectional view in the tire meridian direction (see FIGS. 3 to 5). ). That is, it is preferable that the carcass reinforcing material 8 holds the rolled-up end portion 42 of the carcass layer 4 at the center position. Specifically, the distance D (not shown) in the tire width direction between the center position of the carcass reinforcing material 8 and the rolled-up end portion 42 of the carcass layer 4 is 0 ≦ D / H with respect to the width H of the carcass reinforcing material 8. It is preferable to be within the range of <0.4. Thereby, the carcass reinforcing material 8 can appropriately hold the rolled-up end portion 42 of the carcass layer 4.

  In addition, the end of the carcass reinforcing material 8 on the outer side in the tire width direction and the constituent members of the belt layer 5 (the belt material 51 or the belt cover layers 53 and 54 adjacent to the carcass reinforcing material 8) in a cross-sectional view in the tire meridian direction. It is preferable that it is in a position which mutually differs in the tire width direction (refer FIGS. 3-5). Specifically, the end portion of the carcass reinforcing member 8 and the end portion of the constituent member of the belt layer 5 are preferably arranged at a distance of 5 [mm] or more in the tire width direction. Thereby, the stress concentration at the end of the member is alleviated and the separation of the tread rubber 6 is suppressed.

[effect]
As described above, in the pneumatic tire 1, the carcass reinforcing material that is disposed between the winding end portion 42 of the carcass layer 4 and the belt layer 5 and covers the winding end portion 42 of the carcass layer 4 from the outer side in the tire radial direction. 8 (see FIG. 1 and FIG. 2). In such a configuration, since the carcass reinforcing material 8 holds the winding end portion 42 of the carcass layer 4, peeling of the winding end portion 42 is effectively prevented. Thereby, there exists an advantage which the high-speed durability performance of a tire improves.

  In the pneumatic tire 1, the carcass reinforcing material 8 is made of an organic fiber cord, and the angle θ formed by the fiber direction of the carcass reinforcing material 8 and the tire circumferential direction is −15 [deg] ≦ θ ≦ 15 [deg]. (Not shown). In such a configuration, the fiber direction of the carcass reinforcing material 8 substantially coincides with the tire circumferential direction (0 degree direction), so that the holding force (tag effect) of the winding end portion 42 of the carcass layer 4 by the carcass reinforcing material 8 is appropriately adjusted. Secured. Thereby, there exists an advantage which the high-speed durability performance of a tire improves appropriately.

  Further, in this pneumatic tire 1, the width H of the carcass reinforcing material 8 is in the range of 1.0 ≦ H / W ≦ 4.0 with respect to the wrap width W between the rolled-up end portion 42 of the carcass layer 4 and the belt layer 5. (See FIG. 3). In such a configuration, the ratio H / W between the width H of the carcass reinforcing material 8 and the wrap width W is optimized, so that the holding force of the winding end portion 42 of the carcass layer 4 by the carcass reinforcing material 8 is appropriately ensured. The Thereby, there exists an advantage which the high-speed durability performance of a tire improves appropriately. For example, H / W <1.0 is not preferable because the holding force of the end portion of the carcass layer by the carcass reinforcing material is lowered and the effect of improving the high-speed durability performance cannot be sufficiently obtained. If 4.0 <H / W, the tire weight becomes excessive due to the carcass reinforcing material, which is not preferable.

  Moreover, in this pneumatic tire 1, the thickness t of the carcass reinforcing material 8 is in the range of 0.5 [mm] ≦ t ≦ 1.5 [mm] (not shown). In such a configuration, the holding force of the winding end portion 42 of the carcass layer 4 by the carcass reinforcing material 8 is appropriately ensured by optimizing the width H of the carcass reinforcing material 8. Thereby, there exists an advantage which the high-speed durability performance of a tire improves appropriately. For example, t <0.5 is not preferable because the holding force of the end portion of the carcass layer by the carcass reinforcing material is lowered and the effect of improving the high-speed durability performance cannot be sufficiently obtained. Further, when 1.5 <t, the tire weight becomes excessive due to the carcass reinforcing material, which is not preferable.

  In the pneumatic tire 1, the end portion of the carcass reinforcing material 8 on the outer side in the tire width direction and the constituent member of the belt layer 5 (the belt material 51 adjacent to the carcass reinforcing material 8 or The end portions of the belt cover layers 53 and 54) are located at mutually different positions in the tire width direction (see FIGS. 3 and 4). In such a configuration, stress concentration at the end of the member is alleviated, and separation of the tread rubber 6 is suppressed. Thereby, there exists an advantage which the high-speed durability performance of a tire improves further.

[Applicable to]
The pneumatic tire 1 is preferably applied to a tire having an aspect ratio of 40 or more, and preferably an aspect ratio of 60 or more. Alternatively, it is preferable to apply a tire having an outer diameter of 640 [mm] or more (for example, 16 inches or more for minivan use). In such a tire having a flat rate, the carcass layer tends to be easily damaged at the winding end. Therefore, there is an advantage that the effect of improving the high-speed durability performance of the tire can be obtained more remarkably by applying the tire having such a flat rate.

[performance test]
In this embodiment, a performance test on high-speed durability performance was performed for a plurality of pneumatic tires having different conditions (see FIG. 6). In this performance test, a pneumatic tire having a tire size of 225 / 45R18 is assembled to an applicable rim specified by JATMA, and a normal internal pressure specified by JATMA is applied to the pneumatic tire.

  The performance test for high-speed durability performance was performed using a drum tester with a drum diameter of 1707 mm, running for 2 hours at a speed of 81 km / h and a load load of 88% of the maximum load specified by JATMA. Increase speed by h. Then, the distance traveled until the tire breaks (separation of the rolled-up end of the carcass layer) is measured, and index evaluation is performed based on the measurement result using the conventional example as a reference (100). In this evaluation, the larger the value, the better.

  The tire weight is an index evaluation based on the conventional example as a reference (100). This evaluation is preferably as the numerical value is small, and it can be said to be appropriate if it is 103 or less.

  In the conventional pneumatic tire, the carcass layer has a single-layer structure, and the rolled-up end portion of the carcass layer extends to the inner side in the tire width direction from the end portion on the outer side in the tire width direction of the belt layer. (Not shown). However, the carcass reinforcing material is not arranged.

  In the pneumatic tire of the comparative example, the carcass layer has a two-layer structure, and the rolled-up end portion of the carcass layer is located at the outer end portion of the bead filler in the tire radial direction (not shown). Further, no carcass reinforcing material is arranged.

  In the pneumatic tires 1 of Examples 1 to 7, the carcass layer 4 has a single layer structure, and the winding end portion 42 of the carcass layer 4 extends to the inner side in the tire width direction from the end portion on the outer side in the tire width direction of the belt layer 5. It extends and is disposed below the belt layer 5 (see FIGS. 1 and 2). A carcass reinforcing member 8 is provided between the winding end portion 42 of the carcass layer 4 and the belt layer 5 and covers the winding end portion 42 of the carcass layer 4 from the outer side in the tire radial direction. In a cross-sectional view in the tire meridian direction, the end of the carcass reinforcing member 8 on the outer side in the tire width direction and the end of the constituent member of the belt layer 5 (the belt member 51 adjacent to the carcass reinforcing member 8 or the belt cover layers 53 and 54). Are disposed at positions different from each other in the tire width direction (see FIGS. 3 to 5).

  As shown in the test results, in Examples 1 to 7, it can be seen that the high-speed durability performance of the tire is improved (see FIG. 6). Moreover, when Examples 1-3 are compared, it turns out that the high-speed durability performance of a tire improves effectively by the angle (theta) which the fiber direction of the carcass reinforcing material 8 and the tire peripheral direction are optimized. Further, when Examples 1, 4, and 5 are compared, the ratio H / W of the width H to the lap width W of the carcass reinforcing material 8 is optimized, so that the tire has high speed durability performance while maintaining the tire weight. It can be seen that it can be improved. Further, when Examples 1, 6, and 7 are compared, it can be seen that the high-speed durability performance of the tire can be improved while maintaining the tire weight by optimizing the thickness t of the carcass reinforcing material 8.

  As described above, the pneumatic tire according to the present invention is useful in that the high-speed durability performance of the tire can be improved in a structure in which the rolled-up end portion of the carcass layer extends to the lower layer of the belt layer.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Bead core 3 Bead filler 4 Carcass layer 5 Belt layer 6 Tread rubber 7 Side wall rubber 8 Carcass reinforcing material 41 Main-body part 42 Roll-up edge part 51, 52 Belt material 53, 54 Belt cover layer

Claims (6)

A pneumatic tire in which at least one winding end of the carcass layer extends to the inner side in the tire width direction than the end on the outer side in the tire width direction of the belt layer, and is disposed in the lower layer of the belt layer,
A pneumatic tire, comprising: a carcass reinforcing material that is disposed between a winding end portion of the carcass layer and the belt layer and covers the winding end portion of the carcass layer from the outer side in the tire radial direction.   The carcass reinforcing material is made of an organic fiber cord, and an angle θ between a fiber direction of the carcass reinforcing material and a tire circumferential direction is within a range of −15 [deg] ≦ θ ≦ 15 [deg]. The described pneumatic tire.   3. The width H of the carcass reinforcing member is in a range of 1.0 ≦ H / W ≦ 4.0 with respect to a wrap width W between the rolled-up end portion of the carcass layer and the belt layer. Pneumatic tires.   The pneumatic tire according to any one of claims 1 to 3, wherein a thickness t of the carcass reinforcing material is in a range of 0.5 [mm] ≤ t ≤ 1.5 [mm].   5. Any one of claims 1 to 4, wherein the end portion of the carcass reinforcing member on the outer side in the tire width direction and the end portion of the constituent member of the belt layer are in mutually different positions in the tire width direction in a cross-sectional view in the tire meridian direction. A pneumatic tire according to any one of the above.   The pneumatic tire according to any one of claims 1 to 5, which is applied to a tire having an aspect ratio of 40 or more.