JP2008302878A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of positively deforming a tire profile at high speed traveling and obtaining sufficient riding comfortability. <P>SOLUTION: The pneumatic tire is provided with at least one layer of a carcass layer 4 of a radial ply for reinforcing a pair of side wall parts 2 continued to a bead part 3 over bead cores 5 buried in a pair of bead parts 3 and a tread part 1. The carcass layer 4 has a folded/returned part for rolling-up a periphery of the bead core and is provided with a bead filler extending in an approximately taper-like shape along a carcass body part from the bead core 5 toward the tread part 1 between the folded/returned part and the carcass body part. The bead filler is formed by a high specific gravity material having specific gravity of 1.4-8.0 g/cm<SP>3</SP>near its apex part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and in particular, achieves good ride comfort by actively deforming a tire profile during high-speed running and reducing the longitudinal spring constant of the tire during high-speed rotation. Related to pneumatic tires.

  Conventionally, in general, pneumatic tires tend to become less comfortable during high-speed traveling (for example, 170 to 200 km / h, etc.) when the rotational speed of the tire increases and the frequency of picking up road surface irregularities increases.

  This is a result of intricately intertwining factors such as body rigidity, suspension, and other body components as well as tires, and it is unavoidable because it is a characteristic tuning that emphasizes the normal driving speed range. It has been.

  The present inventors have paid attention to whether or not this problem can be improved by changing the tire ground contact profile during high-speed running, and in particular, focused on the configuration and structure of the bead portion.

  For example, as an investigation of the configuration and ride comfort of the bead part, as a proposal to improve run-flat running durability without incurring deterioration of the ride comfort and road noise of side-reinforced run-flat tires, ordinary bead filler On the other hand, a proposal has been made that a reinforcing rubber layer having a crescent-shaped cross section is arranged in a partly overlapping manner (Patent Document 1).

However, the proposal according to Patent Document 1 is for a run tire for a flat tire, and in particular, the technical idea and the configuration are different from those of the pneumatic tire of the present invention.
JP 2005-297552 A

  In view of the above-described points, an object of the present invention is to provide a pneumatic tire that can positively deform a tire profile during high-speed traveling and obtain a good riding comfort.

  The pneumatic tire of the present invention that achieves the above-described object has the following configuration (1).

(1) At least one radial ply carcass layer is provided between the bead cores embedded in the pair of bead portions to reinforce the tread portion between the pair of sidewall portions connected to the bead portion, and the carcass is disposed around the bead core. A bead filler extending from the bead core toward the tread portion along the carcass main body portion and extending in a tapered manner between the turn-up portion and the carcass main body portion. A pneumatic tire characterized by being formed of a material having a specific gravity of 1.4 to 8.0 g / cm ³ in the vicinity of the top.

  In the pneumatic tire according to the present invention, a pneumatic tire having any one of the following configurations (2) to (6) is preferable as a more specific configuration.

(2) The pneumatic tire according to the above (1), wherein the specific gravity of the high specific gravity material is 1.6 to 1.8 g / cm ³ .

(3) The pneumatic tire according to (1) or (2), wherein the high specific gravity material is used in a usage amount of a cross-sectional area of 1.5 to 30 mm ² in a meridional section of the tire. .

  (4) The pneumatic tire according to any one of (1) to (3), wherein the high specific gravity material is formed of a rubber material mixed with metal powder.

  (5) The pneumatic tire according to any one of (1) to (3), wherein the metal powder is iron or lead powder.

  (6) The pneumatic tire according to any one of (1) to (3), wherein the high specific gravity material is made of a metal wire material.

  According to the present invention, it is possible to positively deform the tire profile during high-speed traveling, and specifically, the direction in which the tire profile stands upright at a portion below the maximum tire width (in the direction of the rotation center axis). In addition, it becomes possible to be deformed in a direction to bend more at a portion above the tire maximum width (in the tire tread portion direction), and by such deformation, the tire spring constant can be reduced. As a result, the ride comfort can be improved.

  Hereinafter, the pneumatic tire of the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a meridional cross-sectional view of a typical tire structure example, and a pair of sidewalls connected to the bead portion 3 between bead cores 5 embedded in the pair of bead portions 3. The carcass layer 4 having at least one radial ply that reinforces the portion 2 and the tread portion 1 is configured as a whole, and the carcass layer 4 has a turn-up portion that winds up around the bead core 5, and the turn-up portion and the carcass A bead filler 8 extending in a tapered manner along the carcass layer 4 main body from the bead core 5 toward the tread portion 1 is provided between the layer main body and the layer main body. In the tread portion 1, a belt layer 6 is disposed on the outer circumferential side of the carcass layer 4, and a belt cover layer 7 that covers the belt layer 6 is disposed on the outer circumferential side of the belt layer 6.

In particular, in the pneumatic tire of the present invention, the bead filler 8 has a specific gravity near the top portion 9 as shown in FIGS. 2B and 2C under the basic structure illustrated in FIG. Is formed of a material having a high specific gravity of 1.4 to 8.0 g / cm ³ , and a conventional rubber material generally used for a bead filler has a specific gravity of 1.2 g / cm ^3. Since it is less than the level, the vicinity of the top 9 having a specific gravity of 1.4 to 8.0 g / cm ³ is considerably heavy.

  FIG. 2A shows a structure other than the present invention in which a bead filler is formed with a uniform specific gravity.

  In the pneumatic tire according to the present invention, in particular, at the top of the bead filler, by using a heavier specific gravity than the portion near the bottom, particularly at the tip of the bead filler, particularly at high speed running and high speed rotation. When the tire is viewed in a cross section in the meridian direction of the tire, the tire profile is the tire profile along with the direction in which the bead filler is erected at the portion below the tire maximum width position 10 (in the direction of the rotation center axis). In the upright direction and above the tire maximum width (in the tire tread portion direction), the portion is deformed in a direction to bend in the tire width direction.

  This state is illustrated in the state shown in FIG. 3, where the solid line indicates the bead filler position and tire profile during high-speed rotation / running, and the broken line indicates normal-speed rotation / running. The bead filler position and the tire profile. As a result of this deformation at high speed, the tire spring constant is reduced and the ride comfort is improved.

In the vicinity of the top portion 9 of the bead filler, the specific structure when formed of a material having a high specific gravity with a specific gravity of 1.4 to 8.0 g / cm ³ is shown in FIG. It may be replaced with a high specific gravity material, or may be wound using a steel cord or the like near the top as shown in FIG. 2 (c). The vicinity of the top formed by the high specific gravity material is integrally formed with the bead filler 8 by adhesion / bonding or the like so that the main body of the bead filler 8 can be brought upright by the rotational centrifugal force. It is good.

According to the knowledge of the present inventors, the specific gravity of the high specific gravity material is within the range of 1.6 to 1.8 g / cm ³ from the viewpoint that the difference from that of the bead filler is not too large and easy to handle. Is preferred. The high specific gravity material is preferably formed of a rubber material mixed with metal powder. As the metal powder, iron or lead powder is practical and preferable.

In addition, with respect to the amount of high specific gravity material used, the desired effect due to centrifugal force can be satisfactorily exhibited, and in the meridian section of the tire, the cross-sectional area is 1.5 to 30 mm ^2. It is preferable.

  Further, when it is desired to significantly increase the specific gravity of the high specific gravity material, it may be formed using a metal wire material such as a steel cord.

Two types of tires according to the present invention having a basic structure shown in FIG. 1 and a bead filler structure according to the present invention (225 / 45R17 94Y, two-carcass layer structure as radial tires (PCR) for passenger cars) 1, 2), the tire of Comparative Example 1 having a conventional bead filler structure, and the tire of Comparative Example 2 having a bead filler structure using a medium specific gravity material having a specific gravity of 1.3 g / cm ³ at the top. Tires were manufactured, and the longitudinal spring constant during rotation was evaluated by an indoor test, and the actual vehicle performance test was performed at high speeds to evaluate the straight running stability and the ride comfort.

  The indoor test for evaluating the longitudinal spring constant (N / mm) during rotation was performed at a tire pressure of 240 kPa, a test load of 6 kPa, and a running speed of 100 mph.

  The evaluation of the actual vehicle performance is performed at a traveling speed of 100 km / hour, and is performed by index evaluation using the tire of Comparative Example 1 as evaluation 100. The larger the index, the better.

  As shown in Table 1, it can be seen that by using the pneumatic tire according to the present invention, the riding comfort during high-speed running is significantly improved.

FIG. 1 is a schematic cross-sectional view taken in the meridian direction showing a general example of a pneumatic tire in order to explain an example of an embodiment of the pneumatic tire of the present invention. FIG. 2 illustrates an example of the form of the bead filler used in the pneumatic tire of the present invention, where (a) is used for a conventional tire, and (b) and (c) are pneumatic tires of the present invention. It is an example of what is used for. FIG. 3 is a tire meridian direction cross-sectional view that schematically explains the deflection state of the tire profile during high-speed running and low-speed running.

Explanation of symbols

1: Tread portion 2: Side wall portion 3: Bead portion 4: Carcass layer 5: Bead core 6: Belt layer 7: Belt cover layer covering belt layer 6 8: Bead filler 9: Top portion of bead filler 10: Maximum tire width position

Claims (6)

At least one radial ply carcass layer is provided between the bead cores embedded in the pair of bead portions to reinforce the pair of sidewall portions connected to the bead portions and the tread portion, and the carcass layer is wound around the bead cores. And a bead filler extending substantially in a tapered manner along the carcass body portion from the bead core toward the tread portion between the turn-up portion and the carcass main body portion. A pneumatic tire characterized by being made of a high specific gravity material having a specific gravity of 1.4 to 8.0 g / cm ³ . 2. The pneumatic tire according to claim 1, wherein a specific gravity of the high specific gravity material is 1.6 to 1.8 g / cm ³ . 3. The pneumatic tire according to claim 1, wherein the high specific gravity material is used in a usage amount of 1.5 to 30 mm ² in a cross-sectional area in a meridional section of the tire.   The pneumatic tire according to any one of claims 1 to 3, wherein the high specific gravity material is formed of a rubber material mixed with metal powder.   The pneumatic tire according to claim 1, wherein the metal powder is iron or lead powder.   The pneumatic tire according to claim 1, wherein the high specific gravity material is formed of a metal wire material.

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