JP2018103760A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire having improved riding comfort even in the case of a fillerless structure. SOLUTION: An annular bead core 6 is arranged between a pair of bead portions 1 in which an annular bead core 6 is embedded and the bead portions 1, and the end portions are arranged from the inside to the outside in the tire width direction without arranging a bead filler around the bead core 6. In the pneumatic tire T provided with the carcass ply 4 wound up toward the tire and the rim strip rubber 7 provided on the outside of the carcass ply 4 at the bead portion 1 and in contact with the rim flange, the tire maximum width position 10 The height h10 is 55 to 70% of the tire cross-sectional height H. [Selection diagram] Fig. 1

Description

  The present invention relates to a pneumatic tire having a fillerless structure in which a bead filler is not disposed in a bead portion.

  Conventionally, in a pneumatic tire, an annular bead core and a bead filler are provided in a bead portion, and a carcass ply is folded back on the inner peripheral side of the bead core and wound up from the inner side to the outer side in the tire width direction. However, since the bead filler has a problem of an increase in weight and cost, a pneumatic tire having a fillerless structure in which the bead filler is omitted has been proposed (for example, Patent Documents 1 and 2).

  By the way, in recent years, the set internal pressure at the time of tire use has been increased for the purpose of fuel efficiency. An increase in internal pressure leads to an increase in tire rigidity, resulting in a deterioration in riding comfort.

Japanese Patent Laid-Open No. 2-11406 JP 2013-39851 A

  This invention is made | formed in view of the said situation, The objective is to provide the pneumatic tire which improved riding comfort, even when it is a case where it is a fillerless structure.

The above object can be achieved by the present invention as described below.
That is, the pneumatic tire according to the present invention is a pair of bead portions in which an annular bead core is embedded, and the bead portion is disposed between the bead portions, and the end portion is arranged in the tire width direction without arranging a bead filler around the bead core. In a pneumatic tire comprising a carcass ply wound up from the inside to the outside, and a rim strip rubber provided on the outside of the carcass ply at the bead portion and capable of contacting a rim flange,
The height of the tire maximum width position is 55 to 70% of the tire cross-sectional height.

  The pneumatic tire of the present invention has a filler-less structure in which no bead filler is disposed on the outer side of the bead core in the tire radial direction. According to the present invention, by setting the height of the tire maximum width position to 55 to 70% of the tire cross-sectional height, the tension generated in the carcass ply at the time of vulcanization molding is reduced and the tire rigidity is reduced. It can be improved.

  In the pneumatic tire according to the present invention, it is preferable that the height of the winding end of the carcass ply is 50 to 100% of the height of the tire maximum width position.

  In the pneumatic tire of the present invention, it is preferable that the height of the outer end in the tire radial direction of the rim strip rubber is 40 to 80% of the height of the tire maximum width position.

  Furthermore, in the pneumatic tire, it is preferable that a winding end of the carcass ply is positioned on the outer side in the tire radial direction of the rim strip rubber.

  A decrease in tire rigidity leads to a decrease in steering stability performance, but the steering stability performance can be improved by optimizing the carcass ply winding height and the rim strip rubber height. At the same time, it is possible to suppress the vibration at the inner portion in the tire radial direction from the tire maximum width position and prevent the deterioration of road noise.

Tire meridian cross-sectional view schematically showing an example of a pneumatic tire according to the present invention Tire meridian cross-sectional view schematically showing an example of a pneumatic tire according to another embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. A pneumatic tire T shown in FIG. 1 includes a pair of bead portions 1, sidewall portions 2 extending outward in the tire radial direction from each of the bead portions 1, and tire radial direction outer ends of the sidewall portions 2. And a tread portion 3 that is connected to the tread. An annular bead core 6 is embedded in the bead portion 1 by covering a converging body such as a steel wire with rubber. In the present invention, a bead filler having a substantially cross-sectional triangle shape is not disposed outside the bead core 6 in the tire radial direction, and a so-called filler-less structure is formed.

  A toroidal carcass ply 4 is disposed between the pair of bead portions 1. At least one carcass ply 4 is provided, and the carcass ply 4 is formed by covering a cord that extends at an angle of approximately 90 ° with respect to the tire equator CL with a topping rubber. The carcass ply 4 is locked in a state in which the end portion 4a is wound up from the inner side to the outer side in the tire width direction without disposing a bead filler around the bead core 6. In other words, the carcass ply 4 is provided with a series of winding plies arranged on the outer side in the tire width direction of the bead core 6 on the main body ply from the tread portion 3 through the sidewall portion 2 to the bead portion 1.

  A rim strip rubber 7 that can come into contact with the rim flange is disposed outside the carcass ply 4 in the bead portion 1. The rim strip rubber 7 rises from the bottom surface of the bead portion 1 to the outer side in the tire radial direction and is provided at least at a portion in contact with the rim flange. Further, a sidewall rubber 8 is disposed outside the carcass ply 4 in the sidewall portion 2.

  On the outer periphery of the tread portion 3 of the carcass ply 4, a belt layer 5 constituted by a plurality (two in this embodiment) of belt plies is disposed. Each belt ply is formed by covering a cord extending obliquely with respect to the tire equator CL with a topping rubber, and the cords are laminated so as to cross each other in opposite directions. On the outer periphery of the belt layer 5, a belt reinforcing layer (not shown) formed by covering a cord extending substantially in the tire circumferential direction with a topping rubber may be disposed. The belt reinforcing layer is disposed so as to cover at least both end portions of the belt layer 5, and can prevent the belt layer 5 from being lifted by a centrifugal force during high-speed running, thereby improving high-speed durability.

  The height h10 of the tire maximum width position 10 is 55 to 70% of the tire cross-section height H. In a general pneumatic tire, the tire maximum width position is located at a height of about 50% of the tire cross-section height. By setting the height h10 of the tire maximum width position 10 to 55 to 70% of the tire cross-section height H, the amount of movement of the carcass ply 4 that is moved by being pressed by the bladder during vulcanization molding is small. The resulting tension is low. Thereby, since tire rigidity falls, riding comfort can be improved. The tire cross-section height H is a height from the nominal rim diameter ND to the tread surface of the tread portion 3 in a state where the air pressure defined by JATMA is filled in the tire meridian cross section.

  The height h4 of the winding end 4a of the carcass ply 4 with reference to the nominal rim diameter ND is preferably 50 to 100% of the height h10 of the tire maximum width position 10. A decrease in tire rigidity leads to a decrease in steering stability performance, but the steering stability performance can be improved by optimizing the winding height of the carcass ply 4.

  In the fillerless structure, the rigidity of the inner portion in the tire radial direction from the tire maximum width position 10 is lower than that of the structure having the bead filler because of the characteristics of the structure, and the secondary bending vibration tends to occur. As a result, the road noise is likely to deteriorate in the low frequency range (60 to 80 Hz). Therefore, from the viewpoint of minimizing the deterioration of the road noise low frequency range (60 to 80 Hz), the height h4 of the winding end 4a of the carcass ply 4 is 70 to 100% of the height h10 of the tire maximum width position 10. It is preferable that

  The height h7 of the outer end 7a in the tire radial direction of the rim strip rubber 7 on the basis of the nominal rim diameter ND is preferably 40 to 80% of the height h10 of the tire maximum width position 10. A decrease in tire rigidity leads to a decrease in steering stability performance, but the steering stability performance can be improved by optimizing the height of the rim strip rubber 7.

  Further, from the viewpoint of minimizing the deterioration of the road noise low frequency range (60 to 80 Hz), the height h7 of the rim strip rubber 7 at the outer end 7a in the tire radial direction is the height h10 of the tire maximum width position 10. It is preferable that it is 60 to 80%.

  Further, from the viewpoint of minimizing the deterioration of the road noise low frequency range (60 to 80 Hz), the winding end 4a of the carcass ply 4 is, as shown in FIG. 1, the outer end 7a in the tire radial direction of the rim strip rubber 7. It is preferable to be located on the outer side in the tire radial direction. Further, the height h4 of the winding end 4a of the carcass ply 4 has a difference of 10% or more of the height h10 of the tire maximum width position 10 with respect to the height h7 of the rim strip rubber 7 at the outer end 7a in the tire radial direction. It is preferable.

<Another embodiment>
In the above-described embodiment, the winding end 4a of the carcass ply 4 is positioned on the outer side in the tire radial direction from the tire radial direction outer end 7a of the rim strip rubber 7, but the winding end 4a of the carcass ply 4 is As shown in FIG. 2, the rim strip rubber 7 may be positioned on the inner side in the tire radial direction from the outer end 7 a in the tire radial direction.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, the evaluation item in an Example etc. measured as follows. The size of the tire used for the test was 205 / 60R16, and was mounted on a rim having a rim size specified by JATMA.

(1) Riding comfort Each tire is mounted on a standard rim, filled with vehicle-designated air pressure and attached to a passenger car, and two test drivers get on it, run on an uneven dry asphalt pavement, and conducted a sensory evaluation . The result of Comparative Example 1 was evaluated with an index of 100, and the larger the index, the better the riding comfort.

(2) Steering stability performance Each tire was mounted on a vehicle, and lane change, turning, etc. were performed on a dry asphalt paved road by one person. And the steering stability performance was evaluated by the sensory test by the driver. The result of Comparative Example 1 was evaluated with an index of 100, and the larger the index, the better the steering stability performance.

(3) Road noise (60-80Hz)
The vehicle traveled at 60 km / h on a dry asphalt pavement with a rough surface, and the reciprocal of the sound pressure level measured with the microphone was indexed at the position of the driver's window side ear. The larger the index, the lower the sound pressure level.

Example 1
As shown in Table 1, assuming that the tire cross-section height H is 100, the height h10 of the tire maximum width position 10 is 70 (70% of H), and the height h4 of the winding end 4a of the carcass ply 4 is 70 (h10 Example 1 was a pneumatic tire in which the height h7 of the outer end 7a in the tire radial direction of the rim strip rubber 7 was 56 (80% of h10). Table 1 shows the measurement results of the evaluation items.

Example 2
As shown in Table 1, assuming that the tire cross-section height H is 100, the height h10 of the tire maximum width position 10 is 70 (70% of H), and the height h4 of the winding end 4a of the carcass ply 4 is 35 (h10 Example 2 was a pneumatic tire in which the height h7 of the outer end 7a in the tire radial direction of the rim strip rubber 7 was 56 (80% of h10). Table 1 shows the measurement results of the evaluation items.

Example 3
As shown in Table 1, assuming that the tire cross-section height H is 100, the height h10 of the tire maximum width position 10 is 70 (70% of H), and the height h4 of the winding end 4a of the carcass ply 4 is 35 (h10 Example 3 was a pneumatic tire in which the height h7 of the tire radial direction outer end 7a of the rim strip rubber 7 was 28 (40% of h10). Table 1 shows the measurement results of the evaluation items.

Example 4
As shown in Table 1, assuming that the tire cross-section height H is 100, the height h10 of the tire maximum width position 10 is 55 (55% of H), and the height h4 of the winding end 4a of the carcass ply 4 is 55 (h10 Example 4 was a pneumatic tire in which the height h7 of the outer end 7a in the tire radial direction of the rim strip rubber 7 was 44 (80% of h10). Table 1 shows the measurement results of the evaluation items.

Example 5
As shown in Table 1, assuming that the tire cross-section height H is 100, the height h10 of the tire maximum width position 10 is 55 (55% of H), and the height h4 of the winding end 4a of the carcass ply 4 is 28 (h10 Example 5 was a pneumatic tire in which the height h7 of the outer end 7a in the tire radial direction of the rim strip rubber 7 was 22 (40% of h10). Table 1 shows the measurement results of the evaluation items.

Example 6
As shown in Table 1, assuming that the tire cross-section height H is 100, the height h10 of the tire maximum width position 10 is 55 (55% of H), and the height h4 of the winding end 4a of the carcass ply 4 is 28 (h10 Example 6 was a pneumatic tire in which the height h7 of the outer end 7a in the tire radial direction of the rim strip rubber 7 was 50 (90% of h10). Table 1 shows the measurement results of the evaluation items.

Comparative Example 1
As shown in Table 2, assuming that the tire cross-section height H is 100, the height h10 of the tire maximum width position 10 is 80 (80% of H), and the height h4 of the winding end 4a of the carcass ply 4 is 40 (h10 50%), and a pneumatic tire in which the height h7 of the outer end 7a in the tire radial direction 7a of the rim strip rubber 7 was 32 (40% of h10). Table 2 shows the measurement results of the evaluation items.

Comparative Example 2
As shown in Table 2, assuming that the tire cross-section height H is 100, the height h10 of the tire maximum width position 10 is 80 (80% of H), and the height h4 of the winding end 4a of the carcass ply 4 is 80 (h10 100%), a pneumatic tire in which the height h7 of the outer end 7a in the tire radial direction of the rim strip rubber 7 was 64 (80% of h10) was defined as Comparative Example 2. Table 2 shows the measurement results of the evaluation items.

Comparative Example 3
As shown in Table 2, assuming that the tire cross-section height H is 100, the height h10 of the tire maximum width position 10 is 50 (50% of H), and the height h4 of the winding end 4a of the carcass ply 4 is 25 (h10 50%), and a pneumatic tire in which the height h7 of the tire radial direction outer end 7a of the rim strip rubber 7 was 20 (40% of h10) was defined as Comparative Example 3. Table 2 shows the measurement results of the evaluation items.

Comparative Example 4
As shown in Table 2, assuming that the tire cross-section height H is 100, the height h10 of the tire maximum width position 10 is 50 (50% of H), and the height h4 of the winding end 4a of the carcass ply 4 is 50 (h10 100%), and a pneumatic tire in which the height h7 of the tire radial direction outer end 7a of the rim strip rubber 7 was 40 (80% of h10) was defined as Comparative Example 4. Table 2 shows the measurement results of the evaluation items.

  In Example 1, the riding comfort was improved as compared with Comparative Example 2. In Example 3, the riding comfort was improved as compared with Comparative Example 1. In Example 4, the riding comfort was improved as compared with Comparative Example 4. In Example 5, riding comfort was improved as compared with Comparative Example 3. Moreover, compared with Example 2, Example 1 improved steering stability performance and reduced road noise. In Example 6, as compared with Example 5, the steering stability performance was improved and the road noise was reduced.

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Carcass ply 4a Winding end of carcass ply 6 Bead core 7 Rim strip rubber 7a Tire radial outer end of rim strip rubber T Pneumatic tire

Claims (4)

A pair of bead portions in which an annular bead core is embedded, and a carcass ply that is arranged between the bead portions and whose end portion is wound from the inner side to the outer side in the tire width direction without placing a bead filler around the bead core. And a rim strip rubber provided outside the carcass ply at the bead portion and capable of contacting a rim flange,
A pneumatic tire characterized in that the height of the tire maximum width position is 55 to 70% of the tire cross-sectional height.   2. The pneumatic tire according to claim 1, wherein a height of a winding end of the carcass ply is 50 to 100% of a height of a tire maximum width position.   The pneumatic tire according to claim 1 or 2, wherein a height of an outer end in a tire radial direction of the rim strip rubber is 40 to 80% of a height of a tire maximum width position. The pneumatic tire according to any one of claims 1 to 3, wherein a winding end of the carcass ply is positioned on an outer side in a tire radial direction of an outer end in a tire radial direction of the rim strip rubber.

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