JP2013035512A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire that can further reduce the rolling resistance of the tire, while effectively removing the risk of the decrease in the steering stability by securing necessary sidewall part rigidity without causing a large increase of the tire weight and deterioration of the riding comfort capability, even though making the sidewall part a thin wall.SOLUTION: One toroidal reinforced core member 10 provided by circling one steel cord to the tire circumferential direction is arranged at each sidewall part area between a separation point e from a rim flange of the tire outside surface and the tire maximum width position P in the attitude that assembles to an application rim R outside of the tire width direction of carcass ply body 5a and filled a regulated internal pressure.

Description

  The present invention provides a toroid-shaped main body part that reaches a tread part through a sidewall part from a pair of bead parts provided with a bead core, and a folded part formed by folding back around the bead core. The present invention relates to a pneumatic tire having one or more carcass plies having, in particular, effectively suppressing collapse deformation of the tire side portion due to the thinning of the tire side portion toward the outside in the tire width direction, The present invention proposes a technique that can realize further reduction in rolling resistance while preventing a decrease in steering stability performance.

  In recent years, with the increasing awareness of environmental protection, tires that are lightweight and have excellent fuel efficiency are being demanded. Under such circumstances, for example, on the outer peripheral side of the bead core, the carcass ply main body part and the folded part The thickness of the tire side portion including the bead portion and the sidewall portion is reduced by reducing the height of the bead filler disposed in the radial direction and gradually decreasing in the radial direction. Tires have been proposed.

  According to this tire, the tire side portion is thinned by reducing the volume of the rubber member constituting the tire side portion, so that the eccentric stiffness decreases, so that the rubber volume is particularly large at the time of tire rolling. The amount of heat generated due to the deformation of the tread portion and the vicinity thereof can be kept small, and the rolling resistance can be effectively reduced.

However, in such a method of reducing the thickness of the tire side part, the radially inner portion of the tire side part largely falls and deforms outward in the width direction of the tire starting from the separation point from the rim flange of the tire side part. As a result, the amount of heat generated by the rubber member disposed on the tire side portion increases due to the large falling deformation, and there is a limit to the reduction of rolling resistance based on the thinning of the tire side portion. .
In addition, this method has a problem that the steering stability performance is lowered due to a decrease in rigidity of the tire side portion.

  On the other hand, a side reinforcing layer made of a plurality of organic fiber cords or steel cords extending at a predetermined angle with respect to the tire radial direction is disposed along the carcass ply on the outer side in the tire width direction of the carcass ply. It is proposed to secure the rigidity of the tire side portion, but if a side reinforcing layer composed of a plurality of cords is provided, the tire weight increases and the fuel consumption of the vehicle deteriorates. In addition, due to the presence of a side reinforcing layer having a certain width in the tire radial direction, the spring constant in the radial direction of the tire, the so-called vertical spring, increases, resulting in a comfortable ride on the vehicle. There was a problem that the performance would be degraded.

  An object of the present invention is to solve such problems of the prior art, and the object of the invention is to increase the tire weight and improve the riding comfort performance even if the tire side portion is thinned. An object of the present invention is to provide a pneumatic tire capable of ensuring the required side portion rigidity without causing a decrease, effectively eliminating the possibility of a decrease in steering stability performance, and further reducing the rolling resistance of the tire.

  The pneumatic tire of the present invention includes a bead core embedded in each of a pair of bead portions, a toroid-like main body portion that reaches the tread portion from the bead portion through the sidewall portion, and the main body portion, A carcass made of one or more carcass plies each having a folded portion that is folded around each bead core, and is defined by being assembled to an applicable rim on the outer side in the tire width direction of the main body portion of the carcass ply. In the tire side area between the position of the separation point from the rim flange and the tire maximum width position on the outer surface of the tire in an unloaded state filled with internal pressure, a single steel cord is made to make one turn in the tire circumferential direction. An annular single reinforcing core member is provided.

Here, “adaptive rim” means a rim specified in the following standards according to the tire size, and “specified internal pressure” means an air pressure specified in accordance with the maximum load capacity in the following standards. “Maximum load capacity” refers to the maximum mass allowed to be applied to a tire according to the following standards.
The standard refers to an industrial standard effective in the region where the tire is produced or used. For example, in the United States, “THE TIRE and RIM ASSOCIATION INC. YEAR BOOK” is used. In Europe, “The European Tire” is used. and RIM Technical Organization's STANDARDDS MANUAL ", and in Japan, the Japan Automobile Tire Association's" JATMA YEAR BOOK ".

  Here, preferably, the wire diameter of a steel cord constituting the reinforcing core member, for example, a monofilament cord, is within a range of 10% to 20% of the total thickness of the tire side portion at the tire maximum width position. To do.

  Here, the reinforcing core member has the above-mentioned separation when the distance in the tire radial direction from the separation point position from the rim flange to the maximum tire width position on the outer side surface of the tire under the above state is H. It is preferable to locate the outer side in the tire radial direction from the point position within a range of 0.2H to 0.6H.

Here, the reinforcing core member is preferably disposed along the outer surface of the carcass ply main body portion, and particularly preferably disposed between the main body portion and the folded portion of the carcass ply.
Preferably, a rubber chafer extending in the tire radial direction along the folded portion is provided outside the folded portion of the carcass ply in the tire width direction, and the reinforcing core member is disposed adjacent to the radially outer end portion of the rubber chafer.

  According to the pneumatic tire of the present invention, one steel cord is made to make one turn in the tire circumferential direction in the tire side region between the separation point position from the rim flange and the tire maximum width position on the outer surface of the tire. Tire width, starting from the separation point of the tire side portion located corresponding to the contact area of the tire when the tire is loaded and rolled by arranging the annular single reinforcing core member The annular reinforcing core member that is torsionally deformed in a part of the circumferential direction against the falling deformation toward the outside in the direction counters with its own torsional rigidity, so that the tire side portion is still thinned, It is possible to effectively suppress a large falling deformation of the tire side portion, and thus an increase in the heat generation amount of the rubber member, and as a result, while preventing a decrease in steering stability performance, the tire Based on further thinning of the id portion, it is possible to realize a further reduction in rolling resistance.

  In addition, in this tire, since a single reinforcing core member provided on each tire side portion is configured by making one steel cord make a round in the tire circumferential direction, a conventional side reinforcing layer comprising a plurality of cords is provided. There is no significant increase in tire weight as in the case of a tire, and there is no risk of deterioration in ride comfort performance due to an increase in longitudinal springs.

  Here, when the steel cord constituting the reinforcing core member is a monofilament cord, the torsional deformation of the tire side portion can exhibit greater torsional rigidity than a twisted cord formed by a plurality of filaments. Therefore, it is possible to more effectively suppress the falling deformation of the tire side portion, sufficiently eliminate the possibility of deterioration of the steering stability performance, and further reduce the rolling resistance.

Here, when the wire diameter of the steel cord constituting the reinforcing core member is within the range of 10% to 20% of the total thickness of the tire side portion at the tire maximum width position, In addition to exerting a large torsional rigidity to sufficiently suppress the falling deformation of the wall part, the rigidity step between the reinforcing core member and the surrounding rubber member is reduced to effectively reduce the durability performance of the tire. Can be prevented.
In other words, if the wire diameter of the steel cord is less than 10% of the total thickness of the tire side portion, the steel cord becomes too thin, and depending on the thickness of the tire side portion, the side portion collapses sufficiently. However, the rolling resistance cannot be reduced to the expected level, and the required steering stability performance may not be ensured. On the other hand, the wire diameter of the steel cord is not adjusted to the total tire side. If it exceeds 20% of the thickness, the tire's durability performance will be increased because the rigidity step between the highly rigid reinforcing core member made of steel cord with a large wire diameter and the surrounding rubber member becomes too large. There are concerns about a decline.

It should be noted that here, when the tire side rolls when the tire rolls, the portion of the side portion that is greatly displaced outward in the tire width direction is the tire radius from the rim flange separation point position on the tire outer surface. Since it is in the range of 0.2H to 0.6H on the outer side in the direction, the reinforcement core member that counters with the torsional rigidity with its own torsional rigidity is positioned within this range, so that the tire side portion falls down. Deformation can be prevented more effectively.
In other words, when the reinforcing core member is positioned in a region outside the range of 0.2H to 0.6H on the outer side in the tire radial direction with respect to the rim flange separation point position on the outer surface of the tire, There is a possibility that the deformation of the tire side portion, particularly where the displacement amount is large, cannot be effectively restrained and the tire side portion cannot be sufficiently prevented from falling down.

Here, when the reinforcing core member is arranged along the outer surface of the carcass ply main body portion, the reinforcing core member having a rigidity higher than that of the surrounding rubber member is close to the carcass ply having the ply cord therein. By doing so, it is possible to relieve the rigidity step between the reinforcing core member and the surrounding members, and to eliminate the possibility of a decrease in the durability performance of the tire.
From the same viewpoint, it is more effective to arrange the reinforcing core member between the main body portion and the folded portion of the carcass ply.

  On the other hand, when the radial length of the folded portion of the carcass ply is short and the reinforcing core member cannot be sandwiched between the main body portion and the folded portion of the carcass ply, the reinforcing core member is attached to the folded portion of the carcass ply. By disposing the rubber chafer adjacent to the outer end in the radial direction of the rubber chafer, which is provided on the outer side in the tire width direction and is more rigid than the surrounding rubber member, it is possible to effectively prevent the deterioration of the durability performance of the tire.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view in the tire width direction showing one embodiment of the present invention with respect to a half portion of a tire. It is a principal part expanded sectional view of the tire shown in FIG. It is a figure similar to FIG. 1 which shows the other example of arrangement | positioning of a reinforcing core member. It is a principal part expanded sectional view which shows an Example tire. It is a principal part expanded sectional view which shows an Example tire. It is a principal part expanded sectional view which shows a conventional example tire. It is a principal part expanded sectional view which shows a comparative example tire.

Embodiments of the present invention will be described below with reference to the drawings.
The tire illustrated in FIG. 1 includes a bead core 2 embedded in a pair of bead portions 1, a toroid-shaped main body portion 5a extending from the bead portion 1 through the sidewall portion 3 to the tread portion 4, and the main body portion 5a. It comprises one or more, in the figure one carcass ply 5 having a folded portion 5b that is continuously folded around the bead core 2.

Here, on the outer peripheral side of the crown region of the carcass ply 5 formed by extending steel cords, organic fiber cords and the like in the radial direction, for example, two belt layers 6 and 7 and a tread rubber 8 forming a tread tread surface. Are arranged in sequence.
In addition, the belt layer that can be provided in one layer or three or more layers can be formed by covering a cord made of steel, organic fiber, etc., extending at an angle with respect to the tire circumferential direction by rubber coating, In the figure, each of the two belt layers 6 and 7 has belt layer cords constituting them extending in directions opposite to each other in the tire circumferential direction.

Here, in the illustrated cross section, the thickness is gradually decreased toward the outer side in the tire radial direction in the region formed between the body portion 5a and the folded portion 5b of the carcass ply 5 on the outer peripheral side of the bead core 2. A bead filler 9 having a substantially triangular shape is disposed.
This bead filler 9 made of a high hardness rubber material has a tire side portion starting from a separation point e of the outer rim surface of the tire and the rim flange of the applied rim R shown in phantom in the figure when the tire is rolling. 12 functions to prevent the tire 12 from falling outward in the tire width direction.
The separation point e refers to a point where the outer surface of the tire is separated from the rim flange of the application rim R under the illustrated tire posture that is assembled to the application rim R and filled with the specified internal pressure in the cross section in the tire width direction. Shall.

  By the way, in recent years, for the purpose of reducing the rolling resistance of the tire, in order to suppress the heat generation amount caused by the rolling load of the tire of the rubber member constituting the tire, for example, in the tire radial direction of the bead filler 9 described above, However, in this case, when the vehicle is running, the tire side portion 12 has a tendency to reduce the thickness of the tire side portion 12. Since a larger amount of falling deformation occurs and the amount of heat generated by the rubber member existing in the tire side portion 12 increases, even if the thickness of the tire side portion 12 is further reduced, the rolling resistance can be further reduced. In addition, the steering stability performance is reduced.

Therefore, in the present invention, the outer side of the carcass ply main body portion 5a in the tire width direction has a steel side region between the position of the separation point e from the rim flange and the tire maximum width position P on the tire outer surface. An annular reinforcing core member 10 is provided in which a single monofilament cord or a twisted cord made of a plurality of filaments is made to make one turn in the tire circumferential direction.
The tire maximum width position P means that the tire is located on the outermost side in the tire width direction on the outer surface of the tire in the illustrated no-load state that is assembled to the applicable rim R and filled with the specified internal pressure.

  According to this, since the annular reinforcing core member 10 is locally torsionally deformed when the tire side portion 12 falls and deforms starting from the separation point e, from the high-rigidity steel cord. Based on the large torsional rigidity of the reinforcing core member 10, the tire side portion 12 can be effectively prevented from falling down, and this can reduce the rolling resistance of the tire while ensuring the required steering stability performance. it can.

  Here, the wire diameter of the steel cord constituting the reinforcing core member 10 is in the range of 10% to 20% of the total thickness t of the tire side portion 12 at the tire maximum width position P, for example, in the range of 0.6 mm to 1.4 mm. This is preferable in that the torsional deformation of the tire side portion 12 can be sufficiently suppressed by causing the reinforcing core member 10 to exhibit a large torsional rigidity.

Here, in order to more effectively exert the function of suppressing the collapse of the tire side portion 12 by the reinforcing core member 10, the radial distance between the position of the separation point e and the maximum tire width position P is set to H. , The reinforcing core member 10 is the portion that is most displaced outward in the tire width direction when the tire side portion 12 is collapsed, as shown in an enlarged view in FIG. It is preferable to be located in a portion within the range of 6H.
In particular, disposing the reinforcing core member 10 at a position away from the separation point e with respect to the rim flange causes the reinforcing core member 10 to fall against deformation of the tire side portion 12 starting from the separation point e. It is effective because it will compete with a large moment arm.

By the way, since the reinforcing core member 10 embedded and arranged in the tire side portion 12 is composed of a steel cord, there is a possibility that a rigidity step with the surrounding rubber member becomes large and the durability performance of the tire is lowered.
For this, the reinforcing core member 10 is disposed along the outer surface of the carcass ply main body portion 5a, so that the reinforcing core member 10 constitutes the carcass ply 5, for example, a radial structure steel cord or the like. Therefore, the rigidity step between the reinforcing core member 10 and its surrounding members can be effectively reduced.

  Here, more preferably, the reinforcing core member 10 is sandwiched and disposed between the main body portion 5a and the folded portion 5b of the carcass ply 5, as shown in FIGS. According to this, since the reinforcing core member 10 is positioned so as to be surrounded by the ply cords constituting the carcass ply 5, this results from the arrangement of the highly rigid reinforcing core member 10 on the tire side portion 12. Therefore, it is possible to effectively eliminate the possibility of a decrease in tire durability performance.

  However, as in the case of the tire illustrated in FIG. 3, for example, when both the height of the bead filler 9 and the folded height of the carcass ply folded portion 5 b are lowered, the reinforcing core member 10 is attached to the carcass. In such a case, the reinforcing core member 10 may be inserted in the tire width direction of the carcass ply folded portion 5b as shown in FIG. By disposing it adjacent to the radially outer end portion of the high hardness rubber chafer 11 that is disposed outside and forms the outer surface of the bead portion, it is possible to effectively prevent a decrease in the durability performance of the tire. .

Next, a tire according to the present invention was prototyped and its performance was evaluated, which will be described below.
The size of each test tire was 195 / 65R15.

As shown in FIG. 1, Example tires 1 to 4 are tires having a bead filler placement height and a carcass ply that has a folded portion that is folded back to a position just before the maximum tire width position. The reinforcing core member is sandwiched between the main body portion and the folded portion.
Here, as shown in Table 1, the wire diameters of the steel cords constituting the reinforcing core members of the example tires 1 to 4 are different from each other.

Further, each of the example tires 5 to 7 corresponds to the radial position of the separation point from the rim flange, as shown in each of FIGS. The position of 0.2H on the outer side in the tire radial direction from the position and the separation point position, and the tire maximum width position, respectively.
Further, as shown in FIGS. 5 (a) and 5 (b), each of the tires 8 and 9 has a short radial length of the carcass ply folded portion, so that the main body portion and the folded portion are separated. The reinforcing core member could not be sandwiched between them.
Here, in the example tire 8, as shown in FIG. 5A, the radially outer end of the rubber chafer provided on the outer side in the tire width direction of the folded portion of the carcass ply and the reinforcing core member are spaced apart from each other. In the tire 9 of Example, as shown in FIG. 5B, the radially outer end of the rubber chafer and the reinforcing core member were positioned adjacent to each other.

  As shown in FIGS. 6A and 6B, the conventional tires 1 and 2 each have a folded portion having a long radial length and a folded portion having a short radial length, as shown in FIGS. In any case, no reinforcing core member was provided.

As shown in FIG. 7 (a), each of the comparative example tires 1 and 2 is replaced with the reinforcing core member, on the outer side in the tire width direction of the carcass ply main body portion, along the outer surface of the main body portion. A side reinforcing layer made of a plurality of steel cords or organic fiber cords extending at an angle of 45 ° with respect to the radial direction was provided.
Moreover, each of the comparative example tires 3 to 5, as shown in FIGS. 7B and 7C, five or three reinforcing core members are arranged in the tire radial direction, and these reinforcing core members are arranged. The carcass ply is disposed between the main body portion and the folded portion.
In any of the above test tires, the total thickness of the tire side portion at the tire maximum width position was 4.5 mm.
Tables 1 and 2 show the specifications of these test tires.

  Each test tire described above is assembled to a 6.0 J rim and filled with an internal pressure of 230 kPa, and various tests are performed to determine rolling resistance, high-speed durability, steering stability, tire vertical springs, and tires. Each of the masses was evaluated as follows.

<Rolling resistance>
The rolling resistance when the test tire is mounted on a steam drum tester with a smooth surface with a diameter of 1707 mm and running under a load condition of 4.0 kN and 196 kPa at a speed of 80 km / h is shown in JIS D4234. It was measured by the specified ellipse method.
The measurement results are shown in Tables 1 and 2 as index values using the conventional tire 1 as a control. In addition, this index value represents that rolling resistance is so small that a numerical value is small.

<High-speed durability performance>
The test tire is mounted on a test machine with a drum diameter of 1707 mm, a high-speed durability test specified in JIS D4230 is performed, and it is further increased by 10 km / h every 30 minutes until the tire breaks. The distance was measured.
Tables 1 and 2 show the measurement results as index values using the conventional tire 1 as a control. The index values of the high-speed durability performance shown in Tables 1 and 2 indicate that the higher the numerical value, the better the high-speed durability performance.

<Steering stability>
The test tires were mounted on an actual vehicle, and various road surfaces were generally run under the following conditions, and the steering stability was evaluated by feeling.
The numerical values shown in Tables 1 and 2 are index values based on the conventional tire 1, and the larger the numerical value, the better the steering stability performance.
Vehicle: 1800cc Front-wheel drive vehicle load: Front seat two passengers Installation position: Installed on all wheels Rim: 6Jx15
Internal pressure: 230 kPa

<Tire vertical spring>
After assembling the tire to the applied rim and adjusting the internal pressure to 230 kPa, the tire was placed on the pseudo road surface, and the amount of displacement in the vertical direction when a constant load of 4.0 kN was applied to the tire in the vertical direction was measured.
The measured values are shown in Tables 1 and 2 as index values where the reciprocal of the displacement amount in the vertical direction of the conventional tire 1 is taken as 100. The index values shown in Tables 1 and 2 indicate that the smaller the numerical value, the smaller the vertical spring of the tire and the better the ride comfort performance.

<Mass of tire>
The measured mass of each test tire is shown in Tables 1 and 2 as index values based on the conventional tire 1.

  From the results shown in Tables 1 and 2, all of Comparative Tires 1 to 5 have a side reinforcement layer or a plurality of reinforcing cores, although the rolling resistance is reduced to some extent as compared with Conventional Tires 1 and 2. Due to the arrangement of the members, the tire mass is increased, and the vertical springs that cause a decrease in ride comfort performance are increased, whereas in each of the tires 1 to 9, the tire mass and the vertical spring are increased. It can be seen that the rolling resistance is reduced without a significant increase.

From the results shown in Table 1, the tires of Examples 1 to 4, 6, 8, and 9 in which the reinforcing core member is disposed in the range of 0.2H to 0.6H on the outer side in the tire radial direction with respect to the separation point position. Compared to the tires 5 and 7 in which the position of the reinforcing core member is out of the above range, the rolling resistance is equal to or further reduced, and the steering stability performance is particularly excellent. It can be seen that it can be demonstrated.
Further, here, the tires of Examples 1 to 4, 6, 7, in which the reinforcing core member is sandwiched between the carcass ply main body portion and the folded portion or arranged adjacent to the radially outer end portion of the rubber chafer. 9 shows that the lowering of the high-speed durability performance can be more effectively prevented than in the tires 5 and 8 due to the large rigidity step between the reinforcing core member and the surrounding rubber member.

  From the above, according to the pneumatic tire of the present invention, the thickness of the sidewall portion is reduced, and the rolling resistance is prevented while preventing the deterioration of the steering stability performance without causing the increase in the tire weight and the steering stability performance. It is clear that can be effectively reduced.

DESCRIPTION OF SYMBOLS 1 Bead part 2 Bead core 3 Side wall part 4 Tread part 5 Carcass ply 5a Main body part 5b Folding part 6,7 Belt layer 8 Tread rubber 9 Bead filler 10 Reinforcement core member 11 Rubber chafer R Applicable rim e Separation point position with rim flange P Tire Maximum width position H Radial distance between the separation point position and the maximum width position

Claims (7)

A bead core embedded in each of the pair of bead portions, a toroid-shaped main body portion that extends from the bead portion through the sidewall portion to the tread portion, and the main body portion is folded around each bead core. A pneumatic tire comprising one or more carcass plies each having a folded portion,
The tire between the separation point position from the rim flange and the tire maximum width position on the outer surface of the tire in the unloaded state, which is assembled to the applicable rim and filled with the specified internal pressure, outside the carcass ply body portion in the tire width direction A pneumatic tire formed by arranging a single annular reinforcing core member in a side region of a single steel cord in the tire circumferential direction.   The pneumatic tire according to claim 1, wherein the wire diameter of the steel cord constituting the reinforcing core member is within a range of 10% to 20% of the total thickness of the sidewall portion at the tire maximum width position.   The pneumatic tire according to claim 1 or 2, wherein the steel cord constituting the reinforcing core member is a monofilament cord.   When the distance in the tire radial direction from the separation point position from the rim flange to the tire maximum width position on the outer side surface of the tire under the unloaded condition is H, the reinforcing core member is positioned at the separation point position. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is positioned in the range of 0.2H to 0.6H on the outer side in the tire radial direction.   The pneumatic tire according to any one of claims 1 to 4, wherein the reinforcing core member is disposed along the outer surface of the carcass ply main body portion.   The pneumatic tire according to any one of claims 1 to 5, wherein the reinforcing core member is disposed so as to be sandwiched between the main body portion and the folded portion of the carcass ply.   A rubber chafer extending in the tire radial direction along the folded portion is provided outside the folded portion of the carcass ply in the tire width direction, and the reinforcing core member is disposed adjacent to the radially outer end portion of the rubber chafer. The pneumatic tire according to any one of 1 to 5.

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