JP2012101647A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel pneumatic tire with improved maneuvering stability, and partial abrasion resistance, by sufficiently reducing ply steer force.SOLUTION: The tire includes a first reinforcing body 14 having one end part 14Elocked in one bead part 3 and the other end part 14Eterminated in a tread part 9 via one sidewall part 6, and a second reinforcing body 15 having one end part 15Elocked in the other bead part 4 and the other end part 15Eterminated in the tread part 9 via the other sidewall part 7. An angle α to a tire equatorial surface E of a belt cord of an inside belt layer 11 and an angle β to the tire equatorial surface E of the belt cord of an outside belt layer 12, satisfy 10≤(α-β)≤30, 10≤β≤20 and 25≤α≤45. A distance W1 in the tire width direction formed by the other end part 14Eand the other end part 15Eand a width W2 of a belt layer of a narrow width, satisfy 0.4×W2≤W1≤0.8×W2.

Description

  The present invention relates to a pneumatic tire in which two belt layers each having a belt cord arranged therein are embedded in a tread portion, and the belt layers are arranged so that the belt cords intersect each other between the two belt layers. In particular, the present invention relates to an apparatus in which price tear force is reduced to improve handling stability and uneven wear resistance.

  As shown in FIGS. 5 and 6, when the tire contacts the ground, the price tear force causes a coupling shear deformation between the belt layers B <b> 1 and B <b> 2 laminated with a curvature, and torque acts on the belt. It is a force generated on the contact surface of the tread portion as a reaction force. As shown in FIG. 7, the price tear force (indicated by “PSF” in the figure) is generated in the same direction on the left and right wheels mounted on the vehicle, and is therefore one of the main causes of vehicle flow. In order to move the vehicle straight against the price tear force, for example, a lateral force (indicated by “SF” in the figure) in a direction and magnitude that cancels the price tear force of the two rear wheels is generated by a steering operation. That is, it is necessary to add a predetermined slip angle θ. Moreover, since the price tear force is an extra lateral force during straight running, it causes wear in the shoulder region of the tread portion. Conventionally, in Patent Document 1, in order to reduce such price tear force, the belt cords of the two belt layers are arranged so as to be asymmetrical with respect to the tire circumferential direction so as to cross each other, and the intersection angle is set. A technique for setting the angle between 53 degrees and 57 degrees has been proposed.

JP-A-9-142104

  However, the above-described conventional technology is merely a reduction in price tear force by paying attention only to the crossing angle formed by the belt cords of the two belt layers, and the effect of reducing the price tear force is still unsatisfactory. It has been found that this is sufficient and does not lead to the desired steering stability and uneven wear resistance.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a novel pneumatic tire that can sufficiently reduce the price tear force and improve the steering stability and the uneven wear resistance.

  In order to solve the above-described problem, a pneumatic tire according to the present invention has two layers in which a tread portion is disposed via a pair of sidewall portions on the radially outer side of a pair of bead portions, and a belt cord is arranged in each tread portion. In the pneumatic tire formed by burying the belt layer and arranging the belt layer so that the belt cords cross each other between the two belt layers, one end portion is locked in one bead portion, A first reinforcing body, which extends from the bead portion to the outside in the tire radial direction and terminates in the tread portion through the one sidewall portion, and is covered with a plurality of ply cords, and one end portion of the other bead A plurality of ply cords that are locked in the portion, extend radially outward from the bead portion, and terminate in the tread portion at the other end through the other sidewall portion. A second reinforcement body coated with a belt, and of the two belt layers, the angle of the belt cord of the belt layer located radially inward with respect to the tire equatorial plane is α, and radially outward. When the angle of the belt cord of the belt layer positioned with respect to the tire equatorial plane is β, the angles α and β satisfy 10 ≦ (α−β) ≦ 30, 10 ≦ β ≦ 20, and 25 ≦ α ≦ 45. The distance in the tire width direction formed between the other end portion of the first reinforcing body and the other end portion of the second reinforcing body is W1, and the width of the belt layer having the smaller width among the two belt layers Is W2, the distance W1 and the width W2 satisfy 0.4 × W2 ≦ W1 ≦ 0.8 × W2.

  In the pneumatic tire of the present invention, the angles α, β, the distance W1, and the width W2 can be measured, for example, in a no-load state in which the tire is mounted on an applicable rim and a predetermined air pressure is set. Here, the “applicable rim” is an industrial standard effective in the area where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK is used. In Europe, ETRTO (European Tire and Rim Technical Organization) is used. ) STANDARD MANUAL, in the US TRA (THE TIRE and RIM ASSOCATION INC.) YEAR BOOK and other rims specified in YEAR BOOK, etc., "predetermined air pressure" corresponds to the tire maximum load capacity of standards such as JATMA for applicable size tires Refers to the air pressure (maximum air pressure).

  In such a pneumatic tire, the first reinforcing body and the second reinforcing body are terminated in the tread portion, and a portion where the reinforcing body is not disposed is provided in the tread portion, thereby reducing the binding force of the belt layer by the reinforcing body. As a result, the cord tension of the outer belt layer increases and the cord tension of the inner belt layer decreases, that is, when the view is changed, the outer belt layer is subjected to a force stretched in the circumferential direction, and the inner belt layer You will receive a force that shrinks in the direction. If this is applied to the principle of expression of the price tear force described with reference to FIGS. 5 and 6, the magnitude of the rotational torque of the belt is reduced, and the price tear force can be sufficiently reduced.

  Therefore, according to this pneumatic tire, the price tear force can be sufficiently reduced. Therefore, when the vehicle is subjected to a disturbance (change in unevenness of the road surface, etc.), the four wheels (two front wheels and two rear wheels) are affected. Fluctuations in force received by the wheels are very small, and fluctuations during straight travel are reduced, improving steering stability. Further, in the case of a general passenger car tire, wear in the shoulder region of the tread portion develops mainly due to lateral force fluctuations. In the pneumatic tire of the present invention, the price tear force is sufficiently reduced. Therefore, the wear resistance of the entire ground contact surface can be improved, and the difference in wear amount between the left and right (uneven wear) with respect to the tire equator surface can be reduced. Furthermore, by providing a portion where the reinforcing body does not exist in a part of the tread portion, it is possible to effectively reduce only the longitudinal rigidity of the tire, and as a result, the vertical direction when traveling on the uneven road surface or the like can be reduced. Since the fluctuation can be reduced, the riding comfort performance related to vibration can be improved. In addition, by providing a part where the reinforcing body does not exist in a part of the tread part, the carcass is lighter than a conventional tire (see FIG. 8) continuously extending from one bead part to the other bead part. Needless to say.

  In the pneumatic tire according to the present invention, it is preferable that the other end portion of the first reinforcement body and the other end portion of the second reinforcement body be positioned between the two belt layers. According to the first reinforcing body, the movement of the other end of the first reinforcing body and the other end of the second reinforcing body during rolling of the tire is sandwiched between the two belt layers and reliably suppressed. Separation between the other end of the second reinforcing member and the other end of the second reinforcing member and the end of the belt layer can be prevented, in other words, the other end of the first reinforcing member and the second reinforcing member. The overlapping width between the other end of the reinforcing member and the belt layer can be reduced.

  According to the present invention, it is possible to provide a novel pneumatic tire capable of sufficiently reducing the price tear force and improving the steering stability and the uneven wear resistance.

1 is a cross-sectional view in the width direction of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a developed plan view showing a configuration of a belt layer in the pneumatic tire of FIG. 1. It is a schematic diagram showing price tear force, lateral force, and slip angle when a pneumatic tire according to the present invention is mounted on a vehicle and traveled. It is sectional drawing of the width direction of the pneumatic tire of other embodiment according to this invention. FIG. 4 is a circumferential cross-sectional view of a belt showing a force generated on the belt when the tire is grounded. It is a figure explaining the principle of expression of price tear power. It is a schematic diagram showing price tear force, lateral force, and slip angle when a conventional pneumatic tire is mounted on a vehicle and traveled. It is sectional drawing of the width direction of the conventional pneumatic tire.

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

  As shown in FIGS. 1 and 2, this pneumatic tire 1 includes a pair of bead portions 3 and 4 that contact a predetermined rim R to maintain internal pressure and transmit driving and braking, and radial directions of the bead portions 3 and 4. It consists of a pair of sidewall portions 6 and 7 connected to the outside and a tread portion 9 extending between the pair of sidewall portions 6 and 7, and belt cords 11a and 12a are arranged in the tread portion 9, respectively. The two belt layers 11 and 12 thus formed are embedded. Hereinafter, of the two belt layers 11 and 12, the belt layer located on the radially inner side is referred to as the inner belt layer 11, and the belt layer located on the radially outer side is referred to as the outer belt layer 12. The belt cord 11a of the inner belt layer 11 and the belt cord 12a of the outer belt layer 12 extend so as to cross each other while inclining on the opposite side across the tire equatorial plane (see FIG. 2).

  The belt cords 11a and 12a constituting the inner belt layer 11 and the outer belt layer 12 are made of steel. As a preferred example, the number of cords per unit width of the inner belt layer 11 is C1 (lines / cm), and the outer belt When the number of cords per unit width of the layer 12 is C2 (lines / cm), C1> C2. When the Young's modulus of one cord of the inner belt layer 11 is E1, and the Young's modulus of one cord of the outer belt layer 12 is E2, E1> E2. The Young's modulus is measured according to JIS Z 2241 (metal material tensile test method).

In the pneumatic tire 1, one end portion 14E ₁ is locked to one of the bead portions 3 extending from the bead portion 3 outward in the tire radial direction, the other end portion 14E ₂ through one of the sidewall portions 6 Ends in the tread portion 9, the first reinforcing body 14 having a plurality of ply cords 14 a covered with rubber, and one end portion 15 E ₁ are locked in the other bead portion 5. extending radially outwardly, the other end portion 15E ₂ via the other side wall portion 7 terminates in the tread portion 9, a plurality of ply cords 15a and the second reinforcing member 15 formed by rubber-coated, is provided ing. The one end portions 14E ₁ and 15E ₁ of the first reinforcing body 14 and the second reinforcing body 15 are folded and locked around the annular bead cores 3a and 4a embedded in the bead portions 3 and 4, respectively. ing. Although the 1st reinforcement body 14 and the 2nd reinforcement body 15 consist of 1 ply in this example and the ply cords 14a and 15a are made of organic fiber, it is not limited to this.

In the pneumatic tire 1 of this embodiment, the angle of the belt cord 11a of the inner belt layer 11 with respect to the tire equatorial plane E is α, and the angle of the belt cord 12a of the outer belt layer 12 with respect to the tire equatorial plane E is β. The angles α and β satisfy 10 ≦ (α−β) ≦ 30, 10 ≦ β ≦ 20, and 25 ≦ α ≦ 45, and the other end portion 14E _{2 of} the first reinforcing body 14 And the other end portion 15E2 of the _second reinforcing member 15 is W1, and the width of the belt layer (herein, the outer belt layer 12) having the smaller width of the two belt layers 11 and 12 is defined as W1. Is W2, the distance W1 and the width W2 satisfy 0.4 × W2 ≦ W1 ≦ 0.8 × W2.

  Next, the operation of the pneumatic tire 1 will be described. First, the principle of the appearance of the price tear force is as described with reference to FIGS. 5 and 6. When a belt layer having a curvature comes in contact with the ground (plane), two belt layers in which belt cords cross each other are arranged. Rotational torque is generated around the ground center. The magnitude of the price tear force depends on the magnitude of this rotational torque, and the magnitude of the rotational torque is the circumferential compression that the outer belt layer receives when the tire tread transitions from the non-grounded state to the grounded state. It is proportional to the force and the circumferential tensile force applied to the inner belt layer. And in the pneumatic tire 1 of this invention, the 1st reinforcement body 14 and the 2nd reinforcement body 15 are terminated in the tread part 9, and the part which does not arrange | position the reinforcement bodies 14 and 15 in the tread part 9 is provided. Since the restraining force of the belt layers 11 and 12 by the reinforcing members 14 and 15 is reduced, the cord tension of the outer belt layer 12 is increased, and the cord tension of the inner belt layer 11 is decreased. The outer belt layer 12 receives a force that is stretched in the circumferential direction, and the inner belt layer 11 receives a force that is contracted in the circumferential direction. If this is applied to the above-described principle of expression of the price tear force, the magnitude of the rotational torque of the belt is reduced, and the price tear force can be sufficiently reduced.

  Therefore, according to this pneumatic tire 1, since the price tear force can be sufficiently reduced, as shown in FIG. 3, the slip angle can be reduced (substantially zero) when mounted on a vehicle. Therefore, when the vehicle travels, fluctuations in the force received by the four wheels (two front wheels and two rear wheels) when subjected to disturbances (such as unevenness of the road surface) are extremely small, and fluctuations during straight travel are reduced. Steering stability is improved. Further, in the case of a general passenger car tire, wear in the shoulder region of the tread portion 9 progresses mainly by lateral force fluctuations. In this pneumatic tire 1, the price tear force is sufficiently reduced. Therefore, the wear resistance of the entire ground contact surface can be improved, and the difference in wear amount between the left and right sides of the tire equator plane E (uneven wear) can be reduced. Furthermore, by providing a portion where the reinforcing bodies 14 and 15 do not exist in the center of the tread portion 9, it is possible to effectively reduce only the longitudinal rigidity of the tire, and as a result, when traveling on an uneven road surface or the like. Since fluctuations in the vertical direction can be reduced, it is possible to improve riding comfort performance related to vibration. It should be noted that the conventional tire 100 in which the carcass 105 extends continuously from one bead portion 103 to the other bead portion 104 by providing portions where the reinforcing bodies 14 and 15 do not exist in a part of the tread portion 9 (FIG. 8). Needless to say, it is lighter than (see).

  The difference between the angle α of the belt cord 11a of the inner belt layer 11 with respect to the tire equator plane E and the angle β of the belt cord 12a of the outer belt layer 12 with respect to the tire equator plane E is less than 10 degrees ((α−β ) <10 degrees), the angle difference (α−β) is too small and the effect of reducing the price tear force is small, and therefore there is a case where no clear performance improvement appears in the steering stability. On the other hand, if the angle difference (α−β) exceeds 30 degrees, the effect of reducing the price tear force is sufficient, but the angle α becomes too large, and the circumferential rigidity of the inner belt layer 11 becomes small. Cornering power may not be obtained, which may lead to a decrease in steering stability.

  When the angle β is less than 10 degrees (β <10 degrees), the angle β of the belt cord 12a of the outer side belt layer 12 is substantially the same as the tire circumferential direction, so that the circumferential rigidity of the belt layer 12 is increased. As a result, it becomes very large and the longitudinal rigidity of the tire becomes too large, so that ride comfort (vibration ride comfort) may be deteriorated. On the other hand, when the angle β exceeds 20 degrees (β> 20 degrees), since the effect of reducing the price tear force is small, there is a case where no clear performance improvement appears in the steering stability.

  When the angle α exceeds 45 degrees (α> 45 degrees), the rigidity in the tire circumferential direction of the inner belt layer 11 becomes small, so that a sufficient cornering force cannot be obtained and the steering stability may be lowered. When the angle α is less than 25 degrees (α <25 degrees), the effect of reducing the price tear force is small, and thus there is a case where no clear performance improvement appears in the steering stability.

Also, a distance W1 in the tire width direction that forms at the other end portion 14E ₂ and the other end portion 15E ₂ of the second reinforcing member 15 of the first reinforcing member 14, the width W2 in the direction of the belt layer 12 having a small width When W1 <0.4 × W2, the portion where the reinforcing bodies 14 and 15 are not present in the tread portion 9 is too small, and the movement of the belt cords 11a and 12a of the belt layers 11 and 12 is the conventional tire. Similarly, the rotational torque of the belt is not sufficiently reduced, and the effect of reducing the price tear force is small. Further, the longitudinal rigidity of the tire cannot be sufficiently reduced, and the riding comfort cannot be sufficiently improved. On the other hand, when the relationship between W1 and W2 is 0.8 × W2 <W1, the effect of reducing the price tear force is sufficient, the steering stability during straight running is improved, and the longitudinal rigidity of the tire is also sufficient. Although also improved ride comfort, and the other end portion 15E ₂ of the other end portion 14E ₂ and the second reinforcing member 15 of the first reinforcing member 14, since the overlapping width of the belt layer 11 and 12 is too small, the early separation is generated between the first end portion of the other end portion 15E ₂ and the belt layer 11, 12 of the other end portion 14E ₂ and the second reinforcing member 15 reinforcing member 14, deterioration of the durability of the tire May lead to

Next, another preferred embodiment according to the present invention will be described with reference to FIG. In the pneumatic tire 1 of the embodiment shown in this figure, the basic configuration of the first reinforcing body 14 and the second reinforcing body 15 is substantially the same as that of the above-described embodiment shown in FIG. 1 of the other end portion 15E ₂ of the other end portion 14E ₂ and the second reinforcing member 15 of the reinforcement member 14, the point arranged therebetween two layers of belt layers 11, 12 differ. That is, the other end portion 15E ₂ of the other end portion 14E ₂ and the second reinforcing member 15 of the first reinforcing member 14 is disposed between the inner belt layer 11 and the outer belt layer 12, these inner belt layer 11 and the outer belt layer 12. According to the pneumatic tire 1 of this embodiment, the other end portion 14E ₂ and the second inner belt layers 11 a movement of the other end portion 15E ₂ of the reinforcing member 15 of the first reinforcing member 14 at the time of tire rolling and and certainly suppressed by the outer belt layer 12, a starting point between the end portion of the other end portion 15E ₂ and the belt layer 11, 12 of the other end portion 14E ₂ and the second reinforcing member 15 of the first reinforcing member 14 and separation can be prevented which, in other words, the other end portion 15E ₂ of the other end portion 14E ₂ and the second reinforcing member 15 of the first reinforcing member 14, the overlapping width of the belt layer 11 and 12 It can also be made smaller than the embodiment of FIG.

  Next, the effects of the application of the present invention were compared with the pneumatic tire according to the present invention (the tires of Examples 1 to 6), the pneumatic tire according to the prior art (the tire of the conventional example), and the pneumatic tire as a comparison (comparison). The tires of Examples 1 and 2 will be described based on the performance evaluation performed. Each of these tires has a tire size of 205 / 55R16. In the performance evaluation, these tires were mounted on a rim having a size of 6 × 16 inches and tested under an internal pressure of 230 kPa.

  Here, the tires of Examples 1 to 6 each have the reinforcing body and the belt structure shown in FIG. 1 or FIG. 4, that is, the angle α of the belt cord of the inner belt layer with respect to the tire equatorial plane, and the outer belt layer. The angle β of the belt cord with respect to the tire equatorial plane satisfies 10 ≦ (α−β) ≦ 30, 10 ≦ β ≦ 20, and 25 ≦ α ≦ 45, and the other end of the first reinforcing body The distance W1 in the tire width direction formed with the other end of the second reinforcing body and the width W2 of the belt layer with the smaller width satisfy 0.4 × W2 ≦ W1 ≦ 0.8 × W2. The details of the configuration of each tire are as shown in Table 1.

  The tire of the conventional example has the structure shown in FIG. 8, that is, the carcass 105 composed of one ply continuous from one bead portion 103 to the other bead portion 104, and 2 arranged outside the crown portion of the carcass 105. The belt layers 106 and 107 of the layers are provided, and the details of the configuration are as shown in Table 1.

  The tires of Comparative Examples 1 and 2 have the reinforcing body and the belt structure shown in FIG. 1 or 4, but the relationship between the angle α and the angle β is 10 ≦ (α−β) ≦ 30, 10 ≦ β ≦ 20, and 25 ≦ α ≦ 45 is not satisfied, or the relationship between the distance W1 and the width W2 does not satisfy 0.4 × W2 ≦ W1 ≦ 0.8 × W2.

  The performance evaluation was carried out for steering stability (when traveling straight), riding comfort performance (when passing on uneven road surfaces) and uneven wear resistance. Steering stability and ride performance were evaluated by feeling each tire mounted on a test vehicle and several experienced test drivers running on the test course. The evaluation results are shown in Table 1. In Table 1, the numerical values related to the steering stability and riding comfort of the tires of Examples 1 to 6 and the tires of Comparative Examples 1 and 2 are expressed as an index with the test result of the conventional tire as 100, The larger the value, the better the performance.

  Uneven wear resistance is measured by comparing each tire with a drum testing machine, running 10,000 km at a constant speed under a load of 4 kN, and measuring and comparing the amount of wear in the tread shoulder area of the tire after running. It was evaluated by doing. The evaluation results are shown in Table 1. In the table, the numerical values relating to the uneven wear resistance of the tires of Examples 1 to 6 and the tires of Comparative Examples 1 and 2 are indicated by an index with the test result of the tire of the conventional example as 100, and the numerical value is large. It shows that it is excellent in uneven wear resistance.

  As is apparent from the evaluation results shown in Table 1, the application of the present invention can improve steering stability and uneven wear resistance, and in addition, good riding comfort can be obtained.

  Thus, according to the present invention, it has become possible to provide a novel pneumatic tire capable of sufficiently reducing the price tear force and improving the handling stability and the uneven wear resistance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 3, 4 Bead part 6, 7 Side wall part 9 Tread part 14 1st reinforcement body 15 2nd reinforcement body 11 Inner belt layer 12 Outer belt layer

Claims (2)

A tread portion is disposed on a radially outer side of the pair of bead portions via a pair of sidewall portions, and two belt layers each having a belt cord arranged therein are embedded in the tread portion, and between the two belt layers. In the pneumatic tire formed by arranging the belt layer so that each belt cord crosses each other,
One ply cord is rubber-coated with one end portion locked in one bead portion, extending from the bead portion to the outer side in the tire radial direction, passing through one sidewall portion, and the other end portion terminating in the tread portion A first reinforcement,
One end is locked in the other bead portion, extends radially outward from the bead portion, and the other end portion ends in the tread portion through the other sidewall portion, and a plurality of ply cords are covered with rubber. A second reinforcing body,
Of the two belt layers, the angle of the belt cord of the belt layer positioned radially inward with respect to the tire equator plane is α, and the angle of the belt cord of the belt layer positioned radially outward with respect to the tire equator plane is When β, the angles α and β satisfy 10 ≦ (α−β) ≦ 30, 10 ≦ β ≦ 20, and 25 ≦ α ≦ 45,
The distance in the tire width direction formed between the other end portion of the first reinforcement body and the other end portion of the second reinforcement body is W1, and the width of the belt layer having the smallest width among the two belt layers is W2. The pneumatic tire is characterized in that the distance W1 and the width W2 satisfy 0.4 × W2 ≦ W1 ≦ 0.8 × W2.   The pneumatic tire according to claim 1, wherein the other end portion of the first reinforcement body and the other end portion of the second reinforcement body are positioned between the two belt layers.

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