JP2014136514A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire in which rolling resistance is made lower than the conventional product.SOLUTION: A pneumatic tire is a pneumatic tire which includes a pair of bead parts 1, a pair of side wall parts 2, a pair of tread parts 3, a pair of bead fillers 7 arranged in the tire radial direction outside of bead cores 6, and a pair of inserts 8 arranged at the bead parts 1, and an aspect ratio of which is not less than 40% and which does not include a rim guard. When the tire is fitted to a standard rim and filled with air to the specification inner pressure in an unloaded condition, the outmost edge position in the tire radial direction of the bead filler 7 is positioned at the tire radial direction outside by -20 mm to 5 mm from the tire radial direction outmost edge of a rim flange 9, the outmost edge position in the tire radial direction of the insert 8 is positioned at the tire radial direction outside by 5 mm to 20 mm from the tire radial direction outmost edge of the rim flange 9, and an angle of the insert 8 is 5 to 40° against the tire radial direction.

Description

  The present invention relates to a pneumatic tire (hereinafter, also simply referred to as “tire”), and more particularly, to a pneumatic tire in which rolling resistance is reduced as compared with the related art.

  In the conventional pneumatic tire, the deformation of the sidewall portion at the time of load rolling is a bending deformation that occurs integrally with the bead core. By increasing the deformation from the sidewall portion to the bead core, the deformation of the tread portion is reduced, whereby the hysteresis loss in the tread portion is reduced and the rolling resistance is reduced. Therefore, as a technique for reducing the rolling resistance, it is generally performed to increase the deformation from the sidewall portion to the bead core.

  On the other hand, by increasing the deformation of the sidewall portion from the bead core, the deformation of the bead portion around the bead core increases. Therefore, if the rigidity of the bead part is lowered more than necessary, the hysteresis loss due to the deformation of the bead part increases, and the hysteresis loss in the tread part is reduced, but the rolling of the entire tire is reduced. Resistance may deteriorate.

  Under such circumstances, various studies have been made on techniques for arranging a reinforcing layer on a sidewall portion or a bead portion of a tire. For example, Patent Document 1 proposes a pneumatic tire in which a high-elasticity organic fiber reinforcing layer is disposed along a carcass from a shoulder of a tread portion to a bead core for the purpose of reducing weight and improving durability. .

Japanese Patent Application No. 2007-188477

  However, the tire described in Patent Document 1 has a reinforcing layer arranged over a wide range as described above. In this case, the rigidity of the entire bead core is reinforced not only from the bead part but also from the side wall part. And the deformation of the bead portion decreases and the deformation of the tread portion increases, which may adversely affect the rolling resistance.

  Then, the objective of this invention is providing the pneumatic tire which reduced rolling resistance compared with the past by reviewing arrangement | positioning of each member in a bead part.

  As a result of intensive studies to solve the above problems, the present inventor has obtained the following idea. That is, the side wall portion is usually composed only of the carcass and the side rubber, and a large hysteresis loss does not occur even if the side wall portion is greatly deformed. On the other hand, the bead part has a larger volume than the side wall part, and there is a bead filler that is generally a high hysteresis loss member, and the hysteresis loss due to deformation such as direct contact with the rim flange and compression stress from the rim. Is a big part. Therefore, in order to reduce the rolling resistance, it is effective to concentrate the deformation on the sidewall portion while suppressing the deformation of the bead portion by increasing the rigidity of the bead portion relative to the sidewall portion.

  Based on such an idea, the present inventor has further intensively studied. As a result, the inventors have found that the above-described problems can be solved by setting the bead core, the bead filler, and the insert in the bead portion to be predetermined, and the present invention has been completed. It came to do.

That is, the pneumatic tire of the present invention includes a pair of left and right bead portions, a pair of sidewall portions that are continuous from the pair of bead portions to the outside in the tire radial direction, a tread portion that is continuous with the pair of sidewall portions, A carcass composed of one or more layers of carcass plies extending in a toroidal shape between a pair of bead cores embedded in each bead portion, a bead filler disposed on the outer side in the tire radial direction of the bead core, and disposed in the bead portion In a pneumatic tire not having a rim guard having a flatness ratio of 40% or more, and an insert having a cord covered with rubber,
When mounted on a standard rim and filled with standard internal pressure, the position of the outermost end in the tire radial direction of the bead filler is -15 mm to 5 mm from the outermost end in the tire radial direction of the rim flange. ,
The position of the outermost end in the tire radial direction of the insert is 5 mm to 20 mm from the outermost end in the tire radial direction of the rim flange, and the angle of the insert is 5 to 40 with respect to the tire radial direction. It is characterized by being °. Here, the standard rim refers to a standard rim determined according to tires in JATMA (FY2012).

  In the tire of the present invention, the position of the innermost end in the tire radial direction of the insert is preferably -5 mm to 10 mm in the tire radial outer side from the outermost end in the tire radial direction of the bead core. In the tire of the present invention, the cord is preferably an organic fiber cord. Further, in the tire according to the present invention, the carcass includes a carcass main body portion that extends in a toroidal shape between the pair of bead cores, and a carcass folded portion that is folded around the bead core from the inner side to the outer side in the tire width direction. And the insert is preferably disposed between the carcass body and the bead filler. Furthermore, in the tire of the present invention, the angle of the insert is preferably 5 to 25 ° with respect to the tire radial direction.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which reduced rolling resistance compared with the past can be provided.

It is a tire width direction sectional view of the pneumatic tire concerning one suitable embodiment of the present invention. (A) is a tire width direction sectional view near a bead part at the time of assembling a pneumatic tire concerning one suitable embodiment of the present invention to a rim, and (b)-(d) are other things of the present invention. FIG. 2 is a cross-sectional view in the tire width direction in the vicinity of a bead portion when the pneumatic tire according to the preferred embodiment is assembled to a rim.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a tire width direction sectional view of a pneumatic tire according to a preferred embodiment of the present invention. A pneumatic tire 10 according to the present invention is a tire having a flatness ratio of 40% or more. As shown in the figure, a pair of left and right bead portions 1 and sidewall portions 2, and a tread portion 3 continuous between both sidewall portions 2 and And extending in a toroidal shape between the bead portions 1 and having a carcass composed of at least one layer (one layer in the illustrated example) of carcass plies 4 that reinforce each of these portions. In the illustrated tire, two belt layers 5 a and 5 b are embedded on the outer side in the tire radial direction of the crown portion of the carcass, and a bead core 6 is embedded in each bead portion 1, and the bead core 6 has a tire radial direction. A bead filler 7 is disposed on the outer side between the main body portion 4 a and the folded portion 4 b of the carcass ply 4.

  In the tire 10 of the present invention, the bead portion 1 is provided with an insert 8 in which a cord is covered with rubber. As will be described later, in the bead portion 1, the deformation in the cross section that greatly affects the hysteresis loss occurs outside the rim flange in the tire radial direction. Therefore, by disposing the insert 8 in the bead portion 1 and suppressing the collapse deformation of the bead portion 1 on the outer side in the tire radial direction from the rim flange, the collapse deformation of the portion from the rim flange to the bead core 6 is suppressed. Yes. The tire 10 of the present invention does not have a rim guard from the viewpoint of weight reduction. Here, the rim guard refers to a protruding portion that protrudes toward the outer side in the tire width direction provided in the bead portion or the sidewall portion in order to prevent damage to the sidewall portion 2 and the rim flange of the tire.

  FIG. 2A is a cross-sectional view in the tire width direction in the vicinity of the bead portion when the pneumatic tire according to one preferred embodiment of the present invention is assembled to the rim, and FIGS. It is a tire width direction sectional view near a bead part at the time of attaching a pneumatic tire concerning other suitable embodiments of the present invention to a rim. In FIG. 2 (a), the insert 8 is disposed on the outer side in the tire width direction than the main body portion 4a of the carcass ply and on the inner side in the tire width direction with respect to the bead filler 7. In FIG. 2 (b), The insert 8 is disposed on the inner side in the tire width direction of the main body portion 4a of the carcass ply. In FIG. 2C, the insert 8 is disposed between the main body portion 4a and the folded portion 4b of the carcass ply. In FIG. 2D, the insert 8 is disposed so as to be sandwiched between the main body portions 4a of the two-layer carcass ply. Among these, the structure shown in FIG. 2A in which the insert 8 is disposed between the carcass main body 4a and the bead filler 7 is preferable.

  In the tire 10 of the present invention, the position of the outermost end in the tire radial direction of the bead filler 7 is the position of the outermost end in the tire radial direction of the rim flange 9 in a no-load state that is mounted on the standard rim and filled with the standard internal pressure. However, -15 mm to 5 mm from the tire radial direction outermost end of the rim flange, that is, the position of the outermost end in the tire radial direction of the bead filler 7 is the tire diameter from the outermost end of the rim flange 9 in the tire radial direction. The range of the inner distance is 15 mm to the outer 5 mm in the direction distance. By setting the outermost end in the tire radial direction of the bead filler 7 in the above range, that is, by using a smaller bead filler 7 than usual, the weight of the tire can be reduced. It is preferably −10 mm to 5 mm on the outer side in the tire radial direction.

  Further, as shown in FIG. 2A, in the pneumatic tire 10 of the present invention, the position of the outermost end in the tire radial direction of the insert 8 is 5 mm to 20 mm from the outermost end in the tire radial direction of the rim flange 9. The outer side in the radial direction, preferably 10 mm to 20 mm, the outer side in the tire radial direction. As described above, since the tire 10 of the present invention uses a bead filler smaller than usual, the rigidity of the bead portion 1 is lowered, and on the contrary, the deformation of the bead portion 1 is increased, and as a result, rolling resistance is increased. There is a risk of getting worse. However, since the tire is a membrane structure and is a product that is used with a high internal pressure, the effect of supplementing rigidity using the tension generated in the reinforcing layer is great. Therefore, in the tire 10 of the present invention, the insert 8 is disposed in the above range, the rigidity of the bead part 1 is supplemented, and the deformation of the sidewall part 2 and the bead part 1 is controlled, whereby hysteresis in the bead part 1 is achieved. The loss is reduced.

  If the outermost end in the tire radial direction of the insert 8 is less than 5 mm from the outermost end in the tire radial direction of the rim flange 9, the entire length of the insert 8 may be buried in the rim flange 9. The effect is reduced. On the other hand, if the outermost end in the tire radial direction of the insert 8 is more than 20 mm from the outermost end in the tire radial direction of the rim flange 9, the rigidity increases from the sidewall portion 2 to the entire bead core 6 and deformation is reduced. On the other hand, at the time of rolling the load, the tread portion 3 is greatly deformed, and the hysteresis loss is increased. As a result, the rolling resistance may be deteriorated. By setting the relationship between the insert 8 and the rim flange 9 as described above, the hysteresis loss of the bead portion 1 can be reduced and the rolling resistance of the entire tire can be reduced.

  Furthermore, in the tire 10 of the present invention, the angle of the insert 8 is 5 to 40 °, preferably 5 to 25 °, more preferably 5 to 20 ° with respect to the tire radial direction. The deformation in the vicinity of the contact position between the bead core 6 and the bead portion 1 with the rim flange 9 is predominantly the deformation in the tire cross section. If only the deformation in the tire cross section is suppressed, it is optimal to set the angle of the insert 8 to 0 ° with respect to the tire radial direction. However, in practice, the bead portion 1 also has hysteresis loss due to deformation in the circumferential direction. Therefore, to reduce the hysteresis loss, it is effective to give rigidity to some extent in the circumferential direction. Therefore, it is appropriate that the angle of the insert 8 has a low angle with respect to the tire radial direction. Therefore, in the tire of the present invention, the angle of the insert 8 is in the range of 5 to 40 °.

  If the insert 8 is arranged at an angle close to the tire circumferential direction, not only the hysteresis loss reduction effect of the bead portion 1 is reduced, but also the circumferential shear deformation from the sidewall portion 2 to the bead core 6 is reduced, and the entire tire is eccentrically deformed. Therefore, it is disadvantageous for rolling resistance with a significant increase in hysteresis loss due to deformation of the tread portion 3.

  In the tire 10 of the present invention, the purpose of arranging the insert 8 in the bead part 1 is to increase the rigidity of the bead part 1, so the insert 8 is arranged close to the bead core 6 that is the starting point of deformation in the tire cross section. It is preferable. In the tire of the present invention, the position of the innermost end in the tire radial direction of the insert 8 is −5 mm to 10 mm in the tire radial outer side from the radially outermost end of the bead core, that is, the position of the innermost end in the tire radial direction of the insert 8. Is preferably 5 mm from the inner side to 10 mm from the outer side in the tire radial direction from the outermost end in the tire radial direction of the bead core. Preferably, it is −5 mm to 5 mm in the tire radial direction outer side from the outermost end in the tire radial direction of the bead core.

  Further, in the tire 10 of the present invention, the cord constituting the insert 8 is not particularly limited, and a steel cord or an organic fiber cord can be used, but an organic fiber cord is preferable in order to prevent an excessive weight increase. . Examples of the organic fiber that can be suitably used as the cord of the insert 8 according to the tire of the present invention include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), nylon, vinylon, and aramid.

  In the tire 10 of the present invention, when an organic fiber cord is used as a cord that is a reinforcing material for the insert 8, the number of organic fiber cords to be driven may be 5 to 60 (lines / 50 mm). Can be obtained by twisting two or three filament bundles made of organic fibers having a fineness of 500 to 2000 dtex.

  In the tire 10 of the present invention, it is only important that the bead portion has the above-described predetermined structure, and there is no particular limitation with respect to other than that. For example, the belt layers 5a and 5b may be arranged in a crossed manner with two layers formed by rubber-drawing steel cords arranged in parallel at a predetermined angle with respect to the tire circumferential direction. In the tire of the present invention, a tread pattern may be appropriately formed on the surface of the tread portion 3, and an inner liner (not shown) may be formed on the innermost layer. Furthermore, in the tire of the present invention, as the gas filled in the tire, normal or air having a changed oxygen partial pressure, or an inert gas such as nitrogen can be used.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Examples 1-19 and Comparative Examples 1-6>
A tire of the type in which the insert 8 is disposed between the carcass main body 4a and the bead filler 7 as shown in FIGS. 1 and 2 was manufactured with a tire size of 155 / 65R14. The carcass ply has a single layer, and the organic fiber cord of the insert was a cord in which two PET filaments having a fineness of 1500 dtx were twisted and bundled. The number of organic fiber cords to be inserted was set to 50/50 mm. Tables 1 to 5 show the position of the outermost end in the tire radial direction of the bead filler, the position of the innermost end in the tire radial direction of the insert, the position of the outermost end in the tire radial direction of the insert, and the angle of the insert. A rolling resistance test was performed on each of the obtained tires according to the following procedure.

<Rolling resistance test>
The tire was mounted on a rated rim (4.5 J) specified by JATMA, and rolling resistance was determined using a drum testing machine having a steel plate surface with a diameter of 1.7 m. The measurement conditions were a speed of 80 km / h, a load of 2.66 kPa, and an internal pressure of 230 kPa. The obtained results are indexed with Comparative Example 1 being a conventional tire as 100, and are shown in Tables 1 to 5. An improvement of 2% or more was evaluated as a significant difference from the viewpoint of market superiority, excluding errors.

※１：リムフランジのタイヤ径方向最外端からのタイヤ径方向外側への距離である。
※２：ビードコアのタイヤ径方向最外端からのタイヤ径方向外側への距離である。
※３：リムフランジのタイヤ径方向最外端からのタイヤ径方向外側への距離である。

* 1: Distance from the outermost end in the tire radial direction of the rim flange to the outer side in the tire radial direction.
* 2: Distance from the outermost end of the bead core in the tire radial direction to the outer side in the tire radial direction.
* 3: Distance from the outermost end in the tire radial direction of the rim flange to the outer side in the tire radial direction.

  From Tables 1-5, it turns out that the rolling resistance of the pneumatic tire of this invention is reduced.

1 Bead part, 2 Side wall part, 3 Tread part, 4 Carcass ply 5 Belt layer, 6 Bead core, 7 Bead filler, 8 Insert 9 Rim flange, 10 Pneumatic tire

Claims (5)

A pair of left and right bead portions, a pair of sidewall portions that continue from the pair of bead portions to the outside in the tire radial direction, a tread portion that continues to the pair of sidewall portions, and a pair of embedded in the pair of bead portions, respectively A carcass made of one or more carcass plies extending in a toroidal shape between bead cores, a bead filler disposed on the outer side in the tire radial direction of the bead core, and a cord disposed on the bead portion and covered with rubber In a pneumatic tire that does not have a rim guard whose flatness is 40% or more,
When mounted on a standard rim and filled with standard internal pressure, the position of the outermost end in the tire radial direction of the bead filler is -15 mm to 5 mm from the outermost end in the tire radial direction of the rim flange. ,
The position of the outermost end in the tire radial direction of the insert is 5 mm to 20 mm from the outermost end in the tire radial direction of the rim flange, and the angle of the insert is 5 to 40 with respect to the tire radial direction. Pneumatic tire characterized in that it is °.   The pneumatic tire according to claim 1, wherein the position of the innermost end in the tire radial direction of the insert is -5 mm to 10 mm in the tire radial outer side from the outermost end in the tire radial direction of the bead core.   The pneumatic tire according to claim 1 or 2, wherein the cord is an organic fiber cord.   The carcass has a carcass main body portion that extends in a toroidal shape between the pair of bead cores, and a carcass folded portion that is folded from the inner side to the outer side in the tire width direction around the bead core, and the insert includes the carcass The pneumatic tire according to claim 1, wherein the pneumatic tire is disposed between a main body and the bead filler.   The pneumatic tire according to any one of claims 1 to 4, wherein an angle of the insert is 5 to 25 ° with respect to a tire radial direction.

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