JP2010221790A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire whose stability on straight traveling is further improved. <P>SOLUTION: The pneumatic radial tire includes a belt layer and a tread 18 formed outside the tire radial direction of the belt layer. The direction of cords of a steel belt of the outermost layer in the tire radial direction constituting the belt layer is constituted to be in the right upper direction. Rib rows 28, 38 are arranged at the mounting side I on the tread 18 while block rows 26G, 26H are arranged at a part of a non-mounting side E. The sum of a land row area at the non-mounting outside E is set within a range of 1.15 to 1.4 times the sum of the land section row area at the mounting inside I. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic radial tire including a belt layer and a tread portion.

  Various performances are required for pneumatic tires for passenger cars (see, for example, Patent Documents 1 to 3). Among them, stability during straight running is particularly important. For stability during straight traveling, it is required that the vehicle travel straight without any lateral displacement including the inclination of the road surface and that the handle holding force is light.

  Considering the straight running state of the vehicle from the tire, it is important to balance with the inclination of the road surface and the balance with the minute force such as the tire moment generated with respect to the load. For this reason, conventionally, this balance is achieved by designing the pattern in consideration of controlling the balance force by devising the distribution and shape of the pattern block (especially the angle setting in the axial direction). Yes.

Japanese Patent Laid-Open No. 11-245626 JP 2005-53311 A JP-A-7-187033

  It has been found as a knowledge that designing the pattern in this way has less influence on the structure of the tire block. For this reason, it has been common in the past to deal with only the contrivance of the pattern using the balance force with the inclination of the road surface by such a contrivance of the pattern as an evaluation criterion.

  However, in recent years, a greater balance force has been demanded in order to improve the stability during straight running, and it has become difficult to cope with the problem only by using a conventionally designed pattern.

  In view of the above fact, an object of the present invention is to provide a pneumatic radial tire with further improved stability during straight traveling.

In order to solve the above problems, the present inventor conducted the following investigation.
For the straight running stability of the vehicle, it is important that the road surface tilt and the lateral force acting on the tire by the balance are balanced, so that the vehicle can run with little handle holding force and less lateral displacement. is there. Considering the tire, a lateral force component and a moment component are generated due to the addition of a load, and the vehicle is asymmetrical with respect to the traveling direction. In this state, the tire is not stable, and it is considered possible to be stabilized by canceling the moment component. When the residual lateral force component in this state balances the slope of the road surface, it can be considered that the vehicle can travel straight ahead stably. That is, the residual lateral force is finally determined by the balance of the initially generated lateral force component and moment component. In order to improve the lateral force level, it is important to raise the initial generated lateral force and moment.

  The lateral force and moment in the applied load state are basically related, and it is considered that the applied point length of the lateral force affects the moment. Therefore, it is necessary to increase the lateral force in the applied load state. The lateral force when a load is applied is a price tear component, and asymmetry of the belt portion is caused by ground deformation. Therefore, the direction of the lateral force is determined by the orientation of the steel cord on the ground surface side. Although the direction of the generated lateral force of the tire contrast changes depending on the rotation direction, even if the direction of the generated lateral force is reversed, the influence of the pattern portion is not canceled out and the influence of the force output side is increased. In other words, in the asymmetric pattern, it is possible to change the pattern configuration on the inside and outside of the vehicle, so the generated lateral force can be improved by optimally setting the inside and outside of the pattern with respect to the generated lateral force depending on the direction of rotation. It becomes possible.

  In Japan, vehicles are basically driven on the left side of the road. Here, the road surface gradually decreases in height from the center to both ends in consideration of drainage and the like. Therefore, it is preferable that a lateral force in the right direction acts on the tire during traveling.

  When the direction of the steel belt on the ground contact surface is increased to the right, the tire axial force is generated in the left direction compared to the traveling direction during forward rotation. In the case of a ring). Since the axial force is generated in the right direction relative to the traveling direction at the time of reverse rotation, the influence of the inner side of the pattern on the ground contact surface is large (especially in the case of the left wheel).

  Therefore, in the pattern, in order to increase the force on the outer side of the mounting, the generated force is increased by increasing the ratio of the grounding land part, and on the inner side of the mounting, the decrease in the grounding land part is compensated as much as possible by the direction of the block. To do. A further effect can be expected by combining block rigidity with them.

  The present inventor has conducted the above-described studies, repeated experiments and further studies, and has completed the present invention.

  The invention according to claim 1 is a pneumatic radial tire including a belt layer and a tread portion formed on the outer side in the tire radial direction of the belt layer, the outermost radial direction tire constituting the belt layer. The belt ply cords are arranged along the diagonally upper right direction, and in the tread portion, the sum of the land portion row areas outside the vehicle is 1.15 to 1.4 of the sum of the land portion row areas inside the vehicle. It is characterized by being within a double range.

  In the first aspect of the present invention, the cord direction of the belt member of the outermost layer in the tire radial direction constituting the belt layer is the upper right direction. Thereby, when the tire rotates forward, a lateral force in the right direction with respect to the traveling direction is generated.

  And in the tread part, the sum total of the land part row | line | column area of vehicle mounting outer side is made into the range of 1.15 to 1.4 times compared with the sum total of the land part row | line area inside vehicle mounting | wearing. Thereby, it is easy to balance the tire moment component and the lateral force component, and when the tire rotates forward, the residual lateral force in the right direction with respect to the traveling direction can be more efficiently improved. Therefore, according to the first aspect of the present invention, the stability during straight traveling is greatly improved as compared with the conventional case.

When it is less than 1.15 times, the lateral force in the right direction with respect to the traveling direction is not so large. In addition, if it is larger than 1.4 times, although there is an effect, the ground contact area is biased to the left and right, that is, the ground contact area is biased to the outside of the vehicle, so other performance such as wear resistance may be adversely affected. This is not preferable.
According to the first aspect of the present invention, the tread portion may be provided with a row of ribs on at least a part of the vehicle mounting inner side and a block row of at least a part of the outer side of the vehicle mounting.

The invention according to claim 2 is characterized in that the belt layer is composed of a plurality of steel belts.
Thereby, the effect obtained by the invention of claim 1 becomes more remarkable.

The invention according to claim 3 is characterized in that, in the tread portion, the sum of the block lengths in the tire width direction is smaller on the inner side of the vehicle than on the outer side of the vehicle.
Thereby, it is easy to make the sum total of the land part row area outside the vehicle mounting within a range of 1.15 to 1.4 times the sum of the land part row area inside the vehicle mounting. Moreover, it is easy to ensure block rigidity in the land part row | line | column inside vehicle mounting.

The invention according to claim 4 is characterized in that five rows of land portions are formed in the tread portion, and rib rows that are continuous in the tire circumferential direction are formed in the vicinity of the tire equator.
Thereby, the effect obtained by the invention of claim 1 can be made more remarkable.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the pneumatic radial tire which further improved the stability at the time of straight running.

It is a tire radial direction sectional view of a pneumatic radial tire concerning one embodiment of the present invention. It is explanatory drawing explaining the structure of the belt layer of the pneumatic radial tire which concerns on one Embodiment of this invention, and a belt protective layer. It is a top view showing a tread part of a pneumatic radial tire concerning one embodiment of the present invention.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. As shown in FIG. 1, a pneumatic radial tire 10 according to an embodiment of the present invention includes a carcass 12 composed of one layer or a plurality of layers, each end of which is folded by a bead core 11.

  An intersecting belt layer 13 composed of two steel belts 14 and 15 is embedded on the outer side in the tire radial direction of the crown portion 12C of the carcass 12. As shown in FIG. 2, a cord 14 </ b> C of a steel belt 14 closer to the carcass 12 (that is, one belt and a steel belt on the inner side in the tire radial direction) is in a direction along the diagonally upper left direction. Then, the cord 15C of the steel belt 15 that is far from the carcass 12 (that is, the two belts and the steel radial outer side belt) 15 has an acute angle α on the right side with respect to the direction along the upper right direction, that is, the tire rotation direction R. It is supposed to be the direction to make.

  Further, a belt protective layer 16 is provided on the outer side of the belt layer 13 in the tire radial direction. The cord 16C of the belt protective layer 16 is disposed in substantially the same direction as the tire equatorial plane CL.

  A tread portion 18 provided with a groove is formed on the outer side of the belt layer 13 in the tire radial direction. As shown in FIG. 3, the tread portion 18 is formed with two circumferential main grooves 22A and 22B on the vehicle mounting inner side I, and two circumferential main grooves 22C and 22D on the vehicle mounting outer side E, respectively. Yes. The circumferential main groove 22B is disposed closer to the tire equatorial plane CL than the circumferential main groove 22A. The circumferential main groove 22C is disposed closer to the tire equatorial plane CL than the circumferential main groove 22D. With this configuration, five rows of land portions are formed in the tread portion 18.

  There are lateral grooves between the circumferential main groove 22A and the circumferential main groove 22B, between the circumferential main groove 22C and the circumferential main groove 22D, and from the circumferential main groove 22D to the tread end T side. As a result, block rows 26 </ b> F to 26 </ b> H are formed in the tread portion 18. A rib row 28 through which the tire equatorial plane CL passes is formed between the circumferential main groove 22B and the circumferential main groove 22C.

  Here, the tread end means that a pneumatic radial tire is mounted on a standard rim specified in JATMA YEAR BOOK (2007 edition, Japan Automobile Tire Association Standard), and is the maximum size and ply rating applicable to JATMA YEAR BOOK. Fills 100% of the air pressure (maximum air pressure) corresponding to the load capacity (internal pressure-load capacity correspondence table) as the internal pressure, and indicates the outermost ground contact portion in the tire width direction when the maximum load capacity is loaded. In addition, when TRA standard and ETRTO standard are applied in a use place or a manufacturing place, it follows each standard.

A circumferential narrow groove 32 is formed in the land portion row 30 between the circumferential main groove 22A and the tread end T. As a result, a rib row 38 is formed between the circumferential narrow groove 32 and the circumferential main groove 22A. A lateral groove 34 is formed between the circumferential narrow groove 32 and the tread end T. As a result, a block row 36 is formed between the circumferential narrow groove 32 and the tread end T. Accordingly, a rib row 38 and a block row 36 are formed in the land portion row 30.
And in the tread part 18, the sum total of the land part row | line area of the vehicle mounting | wearing outer side E is made into the range of 1.15 to 1.4 times compared with the sum total of the land part row | line | column area of the vehicle mounting inner side I.

  Further, in the tread portion 18, the total sum of the land lengths in the tire width direction V is smaller on the vehicle mounting inner side I than on the vehicle mounting outer side E. Here, the total land length A in the tire width direction V on the vehicle mounting outer side E is the width a1 from the tire equatorial plane CL to the end of the rib row 28, the width a2 of the block row 26G, and the block row 26H. It is the sum with the width a3. Further, the total land length B in the tire width direction V on the vehicle mounting inner side I is the width b1 from the tire equatorial plane CL to the end of the rib row 28, the width b2 of the block row 26F, and the land portion row 30. It is the sum with the width b3.

  As described above, in the present embodiment, the direction of the cord 15C of the steel belt 15 of the outermost layer in the tire radial direction constituting the belt layer 13 is set to the upper right direction. Thereby, when the tire rotates forward, a lateral force in the right direction with respect to the traveling direction is generated.

  In addition, in the tread portion 18, the sum A of the land portion row area on the vehicle mounting inner side E is within a range of 1.15 to 1.4 times the sum B of the land portion row area on the vehicle wearing inner side I. (That is, 1.15 ≦ A / B ≦ 1.4). Thereby, when the tire rotates forward, a lateral force in the right direction with respect to the traveling direction is more likely to be generated. Therefore, the stability during straight traveling is greatly improved as compared with the prior art.

  Further, the belt layer 13 is composed of steel belts 14 and 15. Thereby, when the tire rotates forward, a lateral force in the right direction with respect to the traveling direction is more likely to be generated.

The tread portion 18 is formed with five land portion rows, and a rib row 28 continuous in the tire circumferential direction U is formed in the vicinity of the tire equatorial plane CL.
Thereby, the stability improvement effect at the time of straight running becomes more remarkable.

  In the present embodiment, the example in which the circumferential main groove extends linearly in the tire circumferential direction has been described. However, the circumferential main groove may extend in a zigzag manner in the tire circumferential direction, or zigzag in the tire circumferential direction. It may extend in a shape. Here, extending in a zigzag manner in the tire circumferential direction means that a groove portion extending in the same direction as the tire circumferential direction and a groove portion extending inclined with respect to the tire circumferential direction are alternately extended in the tire circumferential direction, This means that the groove portions extending in the same direction as the tire circumferential direction are arranged in a staggered manner. Further, the phrase “zigzag extending in the tire circumferential direction” means that the groove portions that are inclined with respect to the tire circumferential direction extend in the tire circumferential direction while turning back so that the inclination directions are alternate.

<Test example>
In order to confirm the effect of the present invention, the present inventor made two examples of the pneumatic radial tire 10 of the above embodiment (hereinafter referred to as the tire of Example 1 and the tire of Example 2), and the pneumatic radial tire of the conventional example. Two examples of tires (hereinafter referred to as tires of Conventional Example 1 and tires of Conventional Example 2) and three examples of pneumatic radial tires for comparison (hereinafter referred to as tires of Comparative Example 1 and tires of Comparative Example 2) The tire of Comparative Example 3) was prepared, and the residual lateral force generated in the tire during straight running was measured.
In this test example, all tire sizes are PSR 215 / 45R17, and all rim sizes are 7JJ. Table 1 shows the conditions of each tire in this test example.

表１で、残留横力とは、セルフアライニングトルクがゼロの時のコーナーリングフォースをいう。スチールベルトの貼り方向が右上がりとは、スチールベルトのコード方向が右上方向であることを示し、スチールベルトの貼り方向が左上がりとは、スチールベルトのコード方向が左上方向であることを示す。接地陸部の幅とは、実接地の幅内において主溝以外の接地部の幅のことである。Ａ／Ｂ（接地陸部の比率）は、接地陸部面積の比率と考えて良い。

In Table 1, “residual lateral force” refers to the cornering force when the self-aligning torque is zero. A steel belt sticking direction rising to the right means that the cord direction of the steel belt is in the upper right direction, and a steel belt sticking direction to the left means that the cord direction of the steel belt is in the upper left direction. The width of the ground land portion is the width of the ground portion other than the main groove within the actual ground width. A / B (the ratio of the contact land portion) may be considered as the ratio of the contact land area.

  In this test example, a running test was carried out by rotating all tires mounted on the rim, with an internal pressure of 200 kPa and a load of 3.77 kN, and the residual lateral force generated in the tires was measured. The measurement results are also shown in Table 1.

  As can be seen from Table 1, the residual lateral force of the tire of Conventional Example 2 was larger than that of the tire of Conventional Example 1. Then, compared with the tire of the conventional example 2, the tire of the example 1 has a higher residual lateral force, and the tire of the example 2 has a preferable result that the residual lateral force is further higher.

  In the tires of Comparative Examples 1 to 3, when the tire rotated forward, a lateral force in the left direction with respect to the traveling direction was generated. This is determined to be due to the left-up direction of the steel belt in the outermost layer in the tire radial direction. Therefore, when it is desired to generate a lateral force in the left direction with respect to the traveling direction when the tire rotates forward, the component of the pattern (the sum of the widths of the land portion rows at the vehicle mounting inner side E and the vehicle mounting inner side I is It is considered effective to reverse the ratio and the range of the value of A / B to the above embodiment.

  The embodiments of the present invention have been described with reference to the embodiments. However, the above embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. Needless to say, the scope of rights of the present invention is not limited to the above embodiment.

DESCRIPTION OF SYMBOLS 10 Pneumatic radial tire 13 Belt layer 14 Steel belt 14C Cord 15 Steel belt 15C Cord 18 Tread part 26F-H Block row 28 Rib row 30 Land row 38 Rib row 36 Block row E Vehicle wearing outside I Vehicle wearing inside V Tire width direction

Claims (4)

A pneumatic radial tire comprising a belt layer and a tread portion formed on the outer side in the tire radial direction of the belt layer,
The cord of the outermost belt ply in the tire radial direction constituting the belt layer is disposed along the diagonally upper right direction,
In the tread portion, the total of the land portion row area outside the vehicle mounting is within a range of 1.15 to 1.4 times the total sum of the land portion row area inside the vehicle mounting. tire.   The pneumatic radial tire according to claim 1, wherein the belt layer includes a plurality of steel belts.   3. The pneumatic radial tire according to claim 1, wherein, in the tread portion, the sum of the block lengths in the tire width direction is smaller on the inner side of the vehicle than on the outer side of the vehicle.   5. The land portion row of five rows is formed in the tread portion, and a rib row continuous in the tire circumferential direction is formed near the tire equator. 5. The described pneumatic radial tire.

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