JP2009113593A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress advancing of uneven wear while achieving low rolling resistance in a pneumatic tire. <P>SOLUTION: A first side rubber 26 having low modulus of elasticity is arranged so as to be directed from a bead part 12 to a tread 40, and rolling resistance is suppressed to a low degree. A second side rubber 52 having high modulus of elasticity is arranged near a buttress part 54 and deformation of the buttress part 54 from a shoulder part 56 is suppressed in external inputting by traveling. Uneven wear is improved thereby. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that can suppress deterioration in uneven wear while achieving low rolling resistance.

Conventionally, an inner liner, a carcass ply that is a tire case, a side rubber, a cushion rubber, and the like are arranged near the outer end in the tire radial direction of a side portion of a large tire for trucks, buses, etc., and the side rubber is only one kind of rubber. Was composed.
In recent years, as environmental problems have been highlighted, there has been an increasing demand for fuel efficiency improvement for large tires due to low rolling resistance. Up to now, we have been facing each other by changing patterns, case structures, tread materials, etc., but they are approaching their limits.

Therefore, it has been studied to change the physical properties and side structure of the side rubber.
Here, pneumatic tires using rubber that satisfies low rolling resistance as side rubber succeeded in significantly reducing energy loss compared to conventional rubber used on the side. Differed greatly and shifted to the low elasticity side.
Therefore, if one side of the low rolling resistance rubber is applied to the conventional structure, it has low elasticity and low rigidity, so deformation due to external force from the shoulder part to the buttress part increases, resulting in durability, tread shoulder There was a problem that uneven wear and the like on the part side deteriorated.

In order to increase the rigidity of the buttress portion, Patent Document 1 discloses a breaker as a main breaker ply having a ply width of about 0.85 to 1.0 times the tread width, and a sidewall portion from the tread portion to the radially inner side. A method of providing a rubber reinforcing layer between the sub breaker ply and the carcass is disclosed, but in the invention of Patent Document 1, the sub breaker ply and the rubber reinforcing layer It is provided for the purpose of improving stability, and is not intended to suppress uneven wear. Patent Document 1 is mainly intended to suppress the occurrence of cut flaws in the buttress portion, and is not configured to reduce rolling resistance.
JP 2001-146102 A

  The present invention has been made to solve the above problem, and an object of the present invention is to provide a pneumatic tire capable of suppressing deterioration of uneven wear while achieving low rolling resistance.

  The pneumatic tire according to claim 1 includes a carcass straddling from one bead core to the other bead core, a belt disposed on a radially outer side of the carcass, and a tread disposed on a radially outer side of the belt to constitute a tread. Rubber, and a side rubber that is disposed on the outer side in the width direction of the carcass to form a side wall, the side rubber extending from a bead portion toward the tread, and the first side rubber An inner line that is parallel to the tire rotation axis on the carcass side and passes through the maximum width of the tire, and an outer line that passes through the outermost position in the tire radial direction of the belt and is parallel to the tire rotation axis. And a second side rubber having a higher elastic modulus than that of the first side rubber.

Next, the operation of the pneumatic tire according to claim 1 will be described.
First, in rubber used for a pneumatic tire, rolling resistance increases when rubber having a high elastic modulus is used, and rolling resistance decreases when rubber having a low elastic modulus is used.
In the pneumatic tire according to claim 1, the rolling resistance of the pneumatic tire can be reduced by disposing the first side rubber having a low elastic modulus from the bead portion toward the tread.

In addition, on the carcass side of the first side rubber, the inner line passing through the tire maximum width portion and parallel to the tire rotation axis, and passing through the outermost position in the tire radial direction of the belt and parallel to the tire rotation axis By disposing a second side rubber having a higher elastic modulus than the first side rubber, that is, a second side rubber that is harder and more rigid than the first side rubber, in the region between the outer side line and the tire. Deformation in the vicinity of the region portion (so-called buttress portion) with respect to the external input of the tire can be suppressed, and distortion in the circumferential direction and width direction can be reduced by suppressing deformation of the tread on the shoulder portion side (tread end side). Durability and uneven wear are improved.
If the second side rubber having a high elastic modulus is arranged on the inner side in the tire radial direction than the inner line, the rolling resistance increases and it becomes impossible to achieve low rolling resistance.

  In the present invention, the “buttress portion” refers to an inner line that passes through the tire maximum width portion and is parallel to the tire rotation axis on the tire side portion, and passes through the outermost position in the tire radial direction of the belt with respect to the tire rotation axis. Means the area between the parallel outer lines.

  In the present invention, the “shoulder portion” means a region from the buttress portion to the tread contact end on the tire side portion. Here, the ground contact edge means that a pneumatic tire is mounted on a standard rim specified in JATMA YEAR BOOK (2007 edition, Japan Automobile Tire Association Standard), and the maximum load in the applicable size and ply rating in JATMA YEAR BOOK. This is when the maximum load capacity is loaded with an internal pressure of 100% of the air pressure (maximum air pressure) corresponding to the capacity (internal pressure-load capacity correspondence table in bold type). When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the 100% modulus of the second side rubber is set to 200 to 400% of the 100% modulus of the first side rubber. It is characterized by that.

Next, the operation of the pneumatic tire according to claim 2 will be described.
By setting the 100% modulus of the second side rubber (according to JIS K6251; the same shall apply hereinafter) to 200 to 400% of the 100% modulus of the first side rubber, both low rolling resistance and suppression of uneven wear are reliably achieved. can do.

If the 100% modulus of the second side rubber is less than 200% of the 100% modulus of the first side rubber, the elastic modulus of the second side rubber becomes insufficient, and deformation of the buttress portion cannot be suppressed.
On the other hand, if the 100% modulus of the second side rubber exceeds 400% of the 100% modulus of the first side rubber, the elastic modulus of the second side rubber becomes too high, and the deformation concentrates on the first side rubber and becomes a boundary. Separation is likely to occur on the surface.

The invention according to claim 3 is the pneumatic tire according to claim 2, wherein a 100% modulus of the first side rubber is set to 0.08 to 0.12 kg / mm ² , and 100% modulus is set to 0.28-0.32 kg / mm < ² >, It is characterized by the above-mentioned.

Next, the operation of the pneumatic tire according to claim 3 will be described.
100% modulus of the first side rubber set 0.08~0.12kg / mm ^2, by setting 100% modulus of the second side rubber in 0.28~0.32kg / mm ^2, rolling low Resistance and suppression of uneven wear can be achieved at a high level.
Note that if the 100% modulus of the first side rubber and the 100% modulus of the second side rubber are out of the preferred range, it is impossible to achieve both high rolling resistance and suppression of uneven wear.

  According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, the width of the second side rubber when viewed in a cross section along the tire rotation axis is 20 mm. It is characterized by being set above.

Next, the operation of the pneumatic tire according to claim 4 will be described.
By setting the width of the second side rubber to 20 mm or more, uneven wear can be reliably suppressed.

  According to a fifth aspect of the present invention, in the pneumatic tire according to any one of the first to fourth aspects, the thickness of the second side rubber when viewed in a cross section along the tire rotation axis is It is characterized by being set to 2.0 to 5.0 mm.

Next, the operation of the pneumatic tire according to claim 5 will be described.
By setting the thickness of the second side rubber to 2.0 mm or more, uneven wear can be reliably suppressed. In addition, when the thickness of the second side rubber exceeds 0.5 mm, heat generation becomes large, and a failure due to the heat is likely to occur.

  The invention according to claim 6 is the pneumatic tire according to any one of claims 1 to 5, wherein the second side rubber is not disposed between the tread rubber and the carcass. The tread rubber is arranged on the outer side in the tire width direction.

Next, the operation of the pneumatic tire according to claim 6 will be described.
Low loss and low elastic rubber are used to achieve low rolling resistance, and the placement of high elastic rubber on the case side suppresses deformation from the shoulder with large deflection to the side maximum width, and the contact pressure distribution on the shoulder side is uniform. It becomes excellent in uneven wear.

  As described above, since the pneumatic tire of the present invention has the above-described configuration, it has an excellent effect that it is possible to suppress the deterioration of uneven wear while achieving low rolling resistance.

  In FIG. 1, a pneumatic tire 10 according to the present embodiment is for trucks and buses, and is disposed between a pair of bead portions 12 in a toroid shape and is located between the bead portions 12 and a carcass main body portion 14A. The bead core 16 of the bead part 12 has at least one layer of carcass ply 14 having a folded part 14B folded back from the inside to the outside, and a plurality of rubber parts (hard rubber part 18A and soft rubber part 18B) having different hardnesses. And a stiffener 18 extending between the bead core 16 and the outer side in the tire radial direction between the carcass main body portion 14A and the turn-up portion 14B.

  On the outside of the carcass ply 14 in the bead portion 12, a first chafer 20A (one layer in this embodiment) made of steel wire and a second chafer 20B (two layers in this embodiment) made of organic fibers are provided. A chafer layer 20 is disposed, and a rubber chafer 22 is disposed outside the chafer layer 20. In addition, an inner liner 24 is disposed on the inner surface of the tire in tandem with the rubber chafer 22, and a first side rubber 26 that forms the outer surface of the tire is disposed on the outer side in the tire radial direction from the rubber chafer 22. Yes.

  A rubber 34 different from the soft rubber portion 18B is disposed along the second chafer 20B between the second chafer 20B and the soft rubber portion 18B, and between the second chafer 20B and the folded portion 14B. ing. Further, the outer end of the second chafer 20B in the tire radial direction is covered with a rubber 36 for stress relaxation.

  A belt 38 made of a plurality of plies is disposed on the outer side in the tire radial direction of the carcass main body 14A, and a thick tread rubber 42 constituting the tread 40 is disposed on the outer side in the tire radial direction of the belt 38. . A cushion rubber 44 having a substantially triangular cross section is disposed between the vicinity of the end portion of the belt 38 and the carcass main body portion 14A, and a rubber 46 is disposed between the end portion of the belt 38 and the tread rubber 42.

The tread rubber 42 is tapered from the end of the belt 38 toward the inner side in the tire width direction, and the front end in the width direction is in contact with the outer surface in the tire radial direction of the cushion rubber 44.
1, reference numeral L _IN denotes an inner line which is parallel to the street tire rotation axis the maximum width portion P tire, reference numeral L _OUT the tire radial outermost position of the belt 38 (the tire equator The outer line passing through the plane CL) and parallel to the tire rotation axis is shown. In the tire side portion of the pneumatic tire 10 of the present embodiment, the inner line _LIN and the outer line _LOUT The space between the buttress portion 54 and the space between the buttress portion 54 and the ground contact end 40 </ b> E of the tread 40 is a shoulder portion 56.

The tire-width-direction lateral surfaces of the tapered portions 42A of the tread rubber 42 is substantially entirely covered with a first side rubber 26, the carcass side in the tire radial direction outside portion of the first side rubber 26, the inner line L _IN second side rubber 52 of substantially triangular cross section is disposed between the outer line L _OUT and.

  The second side rubber 52 is the thickest at the tip portion of the tread rubber 42, the thickness gradually decreases toward the outer side and the inner side in the tire radial direction, the inner end in the tire radial direction is in contact with the carcass main body portion 14A, and the tire diameter The first side rubber 26 and the cushion rubber 44 are arranged from the inner end in the direction to the apex portion (maximum thickness portion) of the triangle, and the first side rubber 26 extends from the apex portion of the triangle to the outer end in the tire radial direction. It is arranged between the tread rubber 42.

Here, the 100% modulus of the second side rubber 52 is preferably set to 200 to 400% of the 100% modulus of the first side rubber 26, and the 100% modulus of the first side rubber 26 is set to 0.08 to 0%. set .12kg / mm ^2, it is preferable to set 100% modulus of the second side rubber 52 to 0.28~0.32kg / mm ^2.

  The width W of the second side rubber 52 when viewed in a cross section along the tire rotation axis is preferably set to 20 mm or more, and the thickness (maximum thickness) t of the second side rubber 52 is 2.0. It is preferable to set to ˜5.0 mm.

(Function)
In the pneumatic tire 10 of the present embodiment, a low modulus (e.g., 100% modulus 0.08~0.12kg / mm ²⁾ and the first side rubber 26 disposed toward the bead portion 12 to the tread 40 Therefore, rolling resistance can be kept low. Thereby, the fuel consumption of the vehicle can be reduced.

Further, in the pneumatic tire 10 of the present embodiment, the second side rubber 52 having a high elastic modulus (for example, 100% modulus is 0.28 to 0.32 kg / mm ² ) is disposed in the vicinity of the buttress portion 54. The deformation of the buttress portion 54 from the shoulder portion 56 at the time of external input by traveling can be suppressed, the deformation of the tread 40 on the shoulder portion side is suppressed, the distortion in the circumferential direction and the width direction is reduced, and the durability. Uneven wear is improved.

In addition, by setting the 100% modulus of the second side rubber 52 to 200 to 400% of the 100% modulus of the first side rubber 26, it is possible to reliably achieve both low rolling resistance and uneven wear suppression, further, the 100% modulus of the first side rubber 26 is set to 0.08~0.12kg / mm ^2, to set the 100% modulus of the second side rubber 52 to 0.28~0.32kg / mm ² Thus, low rolling resistance and uneven wear suppression can be achieved at a high level.
Further, by setting the width of the second side rubber 52 to 20 mm or more, uneven wear can be reliably suppressed, and the thickness t of the second side rubber 52 is set to 2.0 to 5.0 mm. Thus, uneven wear can be reliably suppressed.

  The present invention is preferably applied to large pneumatic tires, for example, tires for trucks and buses, tires for construction vehicles, etc. according to the classification of JATMA standards, but may also be applied to other types of tires. good.

(Test example)
In order to confirm the effect of the present invention, a pneumatic tire according to a conventional example and a pneumatic tire according to an example to which the present invention is applied are prepared, and tests are performed on rolling resistance, fuel consumption, durability, and wear resistance. And the test was performed.

Example tire: a tire having the structure described in the above embodiment. The thickness of the pneumatic tire 10 measured in the normal direction of the carcass ply 14 is 20.8 mm, the thickness t of the second side rubber 52 is 5.0 mm, and the width W of the second side rubber 52 is 30 mm. It is. Further, the 100% modulus of the first side rubber 26 is 0.1 / mm ² , and the 100% modulus of the second side rubber 52 is 0.3 kg / mm ² .
Conventional tire: a tire obtained by removing the second side rubber from the tire of the example to obtain the first side rubber.
The size of each test tire is 295 / 60R22.5.
・ Rolling resistance: measured with an indoor drum tester. The rim used is 9.00 × 22.5, the measurement load is 32.8 kN, and the speed is 80 km / h. As a result of the test, it was found that the rolling resistance of the pneumatic tire of the example to which the present invention was applied was improved by 5% in comparison with the conventional pneumatic tire.

・ Fuel consumption: After the tires were changed on the same vehicle on the test course and the same mileage was reached, the fuel weights were compared.
As a result of the test, it was found that the fuel consumption of the vehicle equipped with the pneumatic tire to which the present invention was applied was improved by 3% compared to the vehicle equipped with the conventional pneumatic tire.

-Durability: measured with an indoor drum tester. The test was conducted until a failure occurred under the conditions of a normal load of 335 (kg), a speed of 65 km / h, and a temperature of 38 ° C. Evaluation was based on the difference in mileage until failure.

・ Abrasion resistance: A conventional tire and an example tire (side two-layer product) are mounted on a vehicle of the same user and the same operation, and the travel distance of a tire having a groove depth of 1 mm (after wear) is compared. Thus, the wear resistance was compared. As a result of the test, the pneumatic tire of the example improved the abrasion resistance near the shoulder portion of the tread by 10% as compared with the pneumatic tire of the conventional example.

It is sectional drawing along the tire rotating shaft of the pneumatic tire which concerns on one Embodiment of this invention.

Explanation of symbols

10 Pneumatic tire 16 Bead core 14 Carcass ply (carcass)
38 Belt 40 Tread 42 Tread rubber 50 First side rubber 52 Second side rubber L _IN inner line L _OUT outer line P Tire maximum width portion

Claims (6)

A carcass straddling one bead core to the other bead core;
A belt disposed radially outside the carcass;
A tread rubber disposed on the outer side in the radial direction of the belt and constituting a tread;
A side rubber disposed on the outside in the width direction of the carcass to constitute a side wall;
With
The side rubber includes a first side rubber extending from the bead portion toward the tread, an inner line that is parallel to the tire rotation axis on the carcass side of the first side rubber and through the tire maximum width portion. A second side rubber having a higher elastic modulus than the first side rubber, provided in a region between the outermost line parallel to the tire rotation axis and passing through the outermost position in the tire radial direction of the belt; A pneumatic tire characterized by comprising:   2. The pneumatic tire according to claim 1, wherein a 100% modulus of the second side rubber is set to 200 to 400% of a 100% modulus of the first side rubber. 3. 100% modulus of the first side rubber is set to 0.08~0.12kg / mm ^2, 100% modulus of the second side rubber is set to 0.28~0.32kg / mm ^2, The pneumatic tire according to claim 2.   The pneumatic according to any one of claims 1 to 3, wherein a width of the second side rubber when viewed in a cross section along the tire rotation axis is set to 20 mm or more. tire.   The thickness of the said 2nd side rubber when it sees in the cross section along a tire rotating shaft is set to 2.0-5.0 mm, The any one of Claims 1-4 characterized by the above-mentioned. The pneumatic tire according to item.   The said 2nd side rubber is not arrange | positioned between the said tread rubber and the said carcass, but is arrange | positioned on the tire width direction outer side of the said tread rubber, The any one of Claims 1-5 characterized by the above-mentioned. The pneumatic tire according to claim 1.

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