JP2008201379A - Tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire superior in durability, with both reduction in rolling resistance and driving stability. <P>SOLUTION: This tire has an annular tread part 2 grounding on a traveling surface, a pair of sidewall parts 3 arranged on the more inner peripheral side than both right-left sides of the annular tread part 2, and a pair of bead parts 4 arranged on the innermost periphery of the respective sidewall parts 3 and installed in a rim part, and is provided by setting a value (TW/SW) being the ratio of a tread grounding width TW to a section width SW in a range of 0.6-0.75. The respective sidewall parts 3 are formed of a rubber material having rupture strength of 16.0 MPa or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tire having both a reduction in rolling resistance and a stability in handling.

  In recent years, it has been important to reduce rolling resistance of tires in order to reduce the exhaust gas by reducing the fuel consumption of the vehicle from environmental measures. Needless to say, tires that can ensure the stability of maneuvering are required from the viewpoint of traffic safety. From the above, there is a need for a tire that has both reduced rolling resistance and stability in handling.

A general pneumatic tire has a ratio (TW / SW) of the tread contact width TW to the section width SW of 0.8 or more, but in order to reduce the rolling resistance of the tire, the amount of rubber in the tread portion is reduced. In addition, it is only necessary to reduce the force that the tire receives from the running surface. For this purpose, it is effective to reduce the tread contact width TW. However, if the tread ground contact width TW is too narrow, the force that the tire receives from the running surface becomes too small, resulting in a decrease in steering stability. From the above, if the ratio (TW / SW) of the tread ground contact width TW to the section width SW is within a predetermined range smaller than 0.8, both reduction of rolling resistance and stability of steering can be achieved. Patent Document 1 discloses a tire having a (TW / SW) value in the range of 0.55 to 0.70, and Patent Document 2 in the range of 0.3 to 0.6.
JP-A-5-345506 JP-A-7-195908

  However, in the tire having both of the conventional rolling resistance reduction and steering stability described above, since the tread contact width TW is narrower than the section width SW, the tire has a gentle curve from the tread portion to the sidewall portion. It becomes a shape. Therefore, when the tire is subjected to load fluctuations due to unevenness on the running surface, when the tire contact surface spreads outside by cornering, when the tire rides on a curb, when running at low tire pressure, the sidewall portion is The possibility of rubbing against the running surface or the like increases. If the sidewall portion is damaged by rubbing or the like, it will lead to tire failure. Therefore, the conventional tire has both a reduction in rolling resistance and stability in handling, but has a problem of poor durability.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide a tire having both a reduction in rolling resistance and stability in handling and excellent durability. .

  The invention of claim 1 includes an annular tread portion that contacts the running surface, a pair of sidewall portions that are disposed on the inner peripheral side from the left and right sides of the annular tread portion, and an innermost periphery of each sidewall portion. And a pair of bead portions attached to the rim portion, and a ratio (TW / SW) that is a ratio of the tread ground contact width TW to the section width SW is in the range of 0.6 to 0.75. And each said side wall part is formed with the rubber material whose breaking strength is 16.0 Mpa or more, It is characterized by the above-mentioned.

  The invention according to claim 2 is the tire according to claim 1, characterized in that a flatness ratio indicating a ratio (SH / SW) of the section width SW to the section height SH is 60% or less.

  Invention of Claim 3 is the tire of Claim 1 or Claim 2, Comprising: The location of each said side wall part formed with the rubber material whose breaking strength is 16.0 Mpa or more is the said tread part. The region is at least 50% of the section height with respect to the ground plane side.

  According to the first aspect of the present invention, when the (TW / SW) value, which is the ratio of the tread ground contact width TW to the section width SW, is greater than 0.75, the tread ground contact width is increased and the rolling resistance of the tire is reduced. If the value of (TW / SW), which is the ratio of the tread ground contact width TW to the section width SW, is less than 0.6, the lateral force that the tire receives from the running surface is too small, so that steering stability is achieved. I can't. In the present invention, since the (TW / SW) value, which is the ratio of the tread ground contact width TW to the section width SW, is in the range of 0.6 to 0.75, both rolling resistance is reduced and steering stability is provided. be able to.

  Also, since the (TW / SW) value is in the range of 0.6 to 0.75, when running on uneven running surfaces, cornering, curb rides, running with low tire pressure, etc., the side There is a high possibility that the wall portion will rub against the running surface, etc., but since the sidewall portion is made of a rubber having a breaking strength of 16 MPa or more, it will not be easily damaged even if the sidewall portion is rubbed against the running surface etc. Excellent durability. From the above, it is possible to provide a tire having both reduced rolling resistance and stability in maneuvering and excellent durability.

  According to the invention of claim 2, the possibility that the sidewall portion rubs against the traveling surface or the like is further increased, but as described above, even if the sidewall portion rubs against the traveling surface or the like, it is not easily damaged. From the above, it is possible to provide a flat tire having both a reduction in rolling resistance and stability in steering, and excellent durability.

  According to the invention of claim 3, since the rubber having a breaking strength of 16 MPa or more is highly exothermic, an excellent rubber material having a breaking strength of 16 MPa or more is used only in a portion that may be rubbed against the running surface, etc. By using a rubber material with low thermothermal properties at other locations, the heat generation at the sidewall portion can be reduced as much as possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view in the tread width direction of a tire according to a first embodiment of the present invention. As shown in FIG. 1, the tire 1A includes an annular tread portion 2 that contacts the running surface, a pair of sidewall portions 3 that are arranged on the inner peripheral side from the left and right sides of the annular tread portion 2, and each side of the tire 1A. A pair of bead portions 4 are provided on the innermost periphery of the wall portion 3 and attached to a rim portion (not shown) of the tire wheel. The tread portion 2 and the sidewall portion 3 are each formed of a rubber material, and details of the rubber material will be described below.

  A plurality of belt layers 5 are arranged on the inner peripheral surface of the tread portion 2. A carcass layer 6 is disposed on the inner periphery of the belt layer 5 of the tread portion 2 and inside the pair of sidewall portions 3 and the pair of bead portions 4. The carcass layer 6 is arranged at the bead portion 4 so as to wind the bead reinforcing portion 7 including the bead core 7a and the bead filler 7b. Further on the inner side of the carcass layer 6, an inner liner 8 that is a highly airtight rubber layer corresponding to a tube is disposed, and an air filling chamber 9 is formed inside the inner liner 8.

  The tire 1A has a (TW / SW) value that is a ratio of the tread ground contact width TW and the section width SW in a range of 0.6 to 0.75.

  Here, “section width” refers to the maximum width in the tire axial direction. “Tread contact width TW” means that the tire is mounted on the “adaptive rim” and filled with the “specified air pressure”, and the tire is placed in a vertical position on a flat plate, and corresponds to the “specified mass”. The maximum linear distance in the tire axial direction at the contact surface with the flat plate when a load is applied.

  “Applicable rim” refers to a rim defined in the following standards according to the size of the tire. “Specified air pressure” refers to the air pressure specified in accordance with the maximum load capacity in the following standards. “Maximum load capacity” refers to the maximum allowable load on the tire in the following standards. Of mass. The “specified mass” refers to the above maximum load capacity. The “air” here can be replaced with an inert gas such as nitrogen gas or the like. The “standard” is an industrial standard effective in an area where tires are produced or used. For example, in the United States, “YEAR BOOK of THE TIRE AND RIM ASSOCIATION INC.” Is referred to. In Europe, it means “STANDARDS MANUAL of THE European Tire and Rim Technical Organization”. In Japan, it is the “JATMA YEAR BOOK” of the Japan Automobile Tire Association.

  Next, the structure of the rubber material of the tread part 2 and the sidewall part 3 will be described. Since the tread portion 2 is a portion in contact with the traveling surface, the tread portion 2 is formed of a very large rubber material having a large frictional resistance with the traveling surface and having a breaking strength of about 20 to 30 MPa. In the first embodiment, each sidewall portion 3 is formed of a rubber material having a breaking strength of 16.0 MPa or more in all regions. Since the maximum breaking strength of the rubber material is about 30 MPa, each sidewall portion 3 is formed of a rubber material having a breaking strength in the range of 16.0 MPa to 30 MPa.

  As described above, the tire 1A according to the first embodiment is formed in the range of (TW / SW), which is the ratio of the tread contact width TW and the section width SW, in the range of 0.6 to 0.75. Both rolling resistance reduction and steering stability can be provided. That is, if the (TW / SW) value, which is the ratio of the tread ground contact width TW to the section width SW, is larger than 0.75, the tread ground contact width TW becomes large and the rolling resistance of the tire cannot be reduced. / SW) When the value is less than 0.6, the lateral force that the tire receives from the running surface is too small, and the stability of the steering cannot be achieved. As described above, both reduction of rolling resistance and stability of steering can be provided.

  Also, since the (TW / SW) value is in the range of 0.6 to 0.75, when running on uneven running surfaces, cornering, curb rides, running with low tire pressure, etc., the side Although there is a high possibility that the wall portion 3 will rub against the running surface, etc., since an excellent rubber having a breaking strength of 16 MPa or more is used as the rubber material of the sidewall portion 3, it is easy even if the sidewall portion 3 is rubbed against the running surface etc. Is not damaged and has excellent durability. As described above, it is possible to provide the tire 1A that has both the reduction of rolling resistance and the stability of maneuvering and is excellent in durability.

  Next, since the comparative experiment which demonstrates the effect of the tire 1A which concerns on 1st Embodiment was performed, it is demonstrated. The tires used in the experiment are the tires of Examples 1 and 2 that embody the first embodiment, the tires of the conventional examples, and the tires of Comparative Examples 1 to 4. The size of each tire is 225 / 45R17, and the rim size is 7.5 J × 17.

  First, with respect to the tire of the conventional example and the tires of Comparative Examples 1 to 4, the sidewall portion 3 was tested for damage and damage evaluation, steering stability, and reduction of rolling resistance. The TW / SW of each tire, the breaking strength of the rubber material used for the sidewall portion 3, the contact area, and the rubber amount of the tread are as shown in FIG. The contact area and the amount of tread rubber are indicated by the index of the tires of Comparative Examples 1 to 4 with the index of the conventional tire as index 100.

  (1) About the damage and damage evaluation of the side wall part 3, the tire pressure is 230 KPa, and the load is 4 people riding condition, travels 15000 Km within the test course, and after running, the side wall part 3 has the presence or absence of scratch marks, damage The degree was evaluated by relative comparison. The degree of damage was evaluated by measuring the amount of wear in the depth direction of the scratch mark.

  (2) For the stability test of the vehicle, the stability of the vehicle behavior when the lane change was made at 40, 60, 80, 100, and 120 km / h in the test course under the condition that the tire pressure was 230 KPa and the load was 4 passengers. And sensory evaluation of the delay of responsiveness was carried out. When stability and responsiveness comparable to those of the conventional example were obtained, “◯” was given, and when it was inferior to the conventional example, “x” was given.

  (3) For the rolling resistance test, four levels of rolling resistance values of 40, 60, 80, and 100 km / hour were measured with an indoor drum tester under conditions of air pressure of 230 KPa and load of 3.92 KN, and the average was used. Comparative evaluation was made. The rolling resistance was expressed as a ratio of a relative comparison of the conventional example with an index of 100. The smaller the value, the smaller the rolling resistance and the better.

  As can be seen from the experimental results in FIG. 2, in the conventional example in which the TW / SW is 0.8 and the sidewall portion 3 is formed of a rubber material having a breaking strength of 13 to 15 MPa, the stability of the steering can be achieved. The rolling resistance cannot be reduced. In Comparative Example 4 in which the TW / SW is 0.55 and the sidewall portion 3 is formed of a rubber material having a breaking strength of 13 to 15 MPa, the rolling resistance can be most reduced, but the steering stability cannot be achieved. .

  On the other hand, in Comparative Examples 1 to 3 in which the TW / SW is 0.74, 0.70, and 0.61, and the sidewall portion 3 is formed of a rubber material having a breaking strength of 13 to 15 MPa, Both rolling resistance can be reduced. However, in Comparative Examples 1 to 3, the sidewall portion 3 is damaged by rubbing, and there is a problem in durability. That is, in Comparative Examples 1 to 3, it can be concluded that damage has occurred because the sidewall portion 3 is formed of a rubber material having a breaking strength of 13 to 15 MPa.

  Next, based on the experimental results described above, damage to the sidewall portion 3 and damage evaluation experiments were performed on the tire of Comparative Example 5 and the tires of Example 1 and Example 2 according to the present invention. The TW / SW of each tire and the breaking strength of the rubber material used for the sidewall part 3 are as shown in FIG.

  The damage to the sidewall portion 3 and damage evaluation were performed in the same manner as described above, and the experimental results shown in FIG. 3 were obtained.

  As can be seen from the experimental results in FIG. 3, in Comparative Example 5 in which the sidewall portion 3 is formed of a rubber material having a breaking strength of 15 MPa, the sidewall portion 3 is damaged by rubbing, and there is a problem in durability. On the other hand, in Example 1 and Example 2 in which the sidewall portion 3 is formed of a rubber material having a breaking strength of 16 MPa and 17 MPa, there is a problem in durability although the sidewall portion 3 is slightly damaged by rubbing. No results were obtained.

(Second Embodiment)
FIG. 4 is a cross-sectional view in the tread width direction of a tire according to a second embodiment of the present invention. The tire 1B according to the second embodiment is different from the tire according to the first embodiment only in the flatness. That is, the tire has a flatness ratio of 60% or less indicating the ratio of the section width SW to the section height SH (SH / SW).

  Although overlapping, the ratio (TW / SW) of the tread grounding width TW to the section width SW is in the range of 0.6 to 0.75. Each of the sidewall portions 3 is formed of a rubber material having a breaking strength of 16.0 MPa or more in all regions.

  In addition, since the other structure is the same, the same code | symbol is attached | subjected to the same structure location of drawing, and the description is abbreviate | omitted.

  As shown in FIG. 5, in the tire 1B, when the flatness ratio is 60% or less, the amount of distortion of the sidewall portion 3 increases. For this reason, the possibility that the sidewall portion 3 rubs against the running surface or the like is further increased, but as described above, even if the sidewall portion 3 rubs against the running surface or the like, it is not easily damaged. From the above, it is possible to provide a flat tire having both a reduction in rolling resistance and stability in steering, and excellent durability.

  In FIG. 5, tires having flatness ratios of 40, 45, 55, 60, and 65% have tire sizes of 205 / 40R17, 225 / 45R17, 205 / 55R16, 165 / 60R14, and 195 / 65R15.

(Third embodiment)
FIG. 6 is a cross-sectional view in the tread width direction of a tire according to a third embodiment of the present invention. A tire 1C according to the third embodiment is different from the tire according to the first embodiment only in the configuration of the sidewall portion 3. That is, each sidewall portion 3 is divided into at least 50% or more of the section height SH with respect to the ground contact surface side of the tread portion 2, and only the upper region 3A has a breaking strength rubber of 16.0 MPa or more. It is made of material. The lower region 3B is formed of a rubber material having a breaking strength of 13 to 15 MPa.

  In addition, since the other structure is the same, the same code | symbol is attached | subjected to the same structure location of drawing, and the description is abbreviate | omitted.

  In the third embodiment, since the rubber having a breaking strength of 16 MPa or more has high heat generation properties, the rubber is used only in a portion (upper region 3A) that may be rubbed with a running surface or the like, and other portions (lower region). For 3B), by using a rubber material having low thermothermal property, the exothermic property of the sidewall portion 3 can be reduced.

  Next, since a comparative experiment was conducted to demonstrate the reason why the region where the rubber material having a breaking strength of 16 MPa or more is used for the sidewall portion 3 is 50% or more of the section height SH with the tread portion 2 as a reference, Will be explained. The tires used in the experiment are the tires of Examples 3 and 4 that implement the third embodiment, and the tire of Comparative Example 6. The size of each tire is 225 / 45R17, and the rim size is 7.5 J × 17.

  The TW / SW of each tire and the breaking strength of the rubber material used for the sidewall portion 3 are as shown in FIG. In addition, the index of rolling resistance was represented by the index of tires of Examples 3 and 4 and Comparative Example 6, with the tire of the conventional example (see FIG. 2) as index 100.

  About the damage of the side wall part 3 and damage evaluation, it carried out similarly to the above. As can be seen from the experimental results in FIG. 7, in Comparative Example 6 where the dividing position of the sidewall portion 3 is 40% of the section height SH, the sidewall portion 3 is confirmed to be greatly damaged due to rubbing, and there is a problem in durability. is there. On the other hand, in Example 3 and Example 4 in which the dividing position of the sidewall part 3 is 50% and 60% of the section height SH, although there is a small rubbing on the sidewall part 3, there is a problem in durability. No results were obtained.

  In addition, in the sidewall part 3, since the range exceeding 65% of the section height SH is a range exceeding the side bent part, it is necessary to set the division position of the upper region 3A and the lower region 3B to a position of 65% or more. Absent. That is, each sidewall portion 3 has a position where the section height SH is 50% or more and 65% or less of the section height SH with respect to the ground contact surface side of the tread portion 2, and has a breaking strength of 16.0 MPa or more in the upper region 3A. It is practical to use a rubber material having a breaking strength of 13 to 15 MPa in the lower region 3B.

It is sectional drawing of the tread width direction of the tire which concerns on the 1st Embodiment of this invention. It is a figure which shows the experimental result of the tire of a prior art example, and the tire of Comparative Examples 1-4. It is a figure which shows the experimental result of the tire of Example 1, 2 and the tire of the comparative example 5 which actualized 1st Embodiment. It is sectional drawing of the tread width direction of the tire which concerns on the 2nd Embodiment of this invention. It is a figure which shows the relationship between a flat rate and the distortion state of a sidewall part. It is sectional drawing of the tread width direction of the tire which concerns on the 3rd Embodiment of this invention. It is a figure which shows the experimental result of the tire of Example 3, 4 and the tire of the comparative example 6 which actualized 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A-1C Tire 2 Tread part 3 Side wall part 3A Upper area | region 3B Lower area | region 4 Bead part 5 Belt layer 6 Carcass layer 7 Bead reinforcement part 8 Inner liner 9 Air filling chamber

Claims (3)

An annular tread portion that contacts the running surface, a pair of sidewall portions disposed on the inner peripheral side from the left and right sides of the annular tread portion, and disposed on the innermost periphery of each sidewall portion, A pair of bead portions to be attached, and a tire having a ratio (TW / SW) that is a ratio of a tread ground contact width TW and a section width SW in a range of 0.6 to 0.75,
Each of the sidewall portions is formed of a rubber material having a breaking strength of 16.0 MPa or more.   2. The tire according to claim 1, wherein a flatness ratio indicating a ratio (SH / SW) of the section width SW and the section height SH is 60% or less.   The location of each side wall portion formed of a rubber material having a breaking strength of 16.0 MPa or more is a region that is at least 50% of the section height with respect to the ground contact surface side of the tread portion. The tire according to claim 1 or 2.

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