JPH04100706A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To improve straight-going performance by inclining the straight line connecting the circumferential central points at the radially inner end and the outer end of respective blocks in the width-directional one side end toward the radially outside to the normal of the tread on the circumferential one side, and by inclining the respective blocks on the width-directional other side end in the opposite direction. CONSTITUTION:A tire 1 comprises a pair of beads and a carcass layer 3, and the cords 10, 11 embedded inside the belt plies 8, 9 of the carcass layer 3 are extended in the opposite direction to each other. The straight line L connecting the circumferential central point R at the radially inner end and the circumferential central point S at the radially outer end of the blocks 21a, 21b of the block row positioned at least on the width-directional one side end, out of a plurality of block rows 22 consisting of blocks 21 defined by main grooves 19 and transverse grooves 20 on the outer surface of the tread 18, is inclined toward one side in the circumferential direction as it goes to the radially outside to the normal T of the tread 18. And, the blocks 21d, 21e of the block row positioned at least on the width-directional other side end are inclined in the opposite direction to the above.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a pneumatic radial tire with improved straight running performance.

In general, pneumatic radial tires have a belt layer consisting of two or more belt plies in which cords are embedded, but the cords of such belt plies are Because of the inclination, the pneumatic radial tire is subjected to self-lining torque generated by the inclined cords, especially the outermost belt ply cords, resulting in a decrease in straight running performance.

For this reason, conventionally, as described in JP-A-54-55902, for example, the direction of the tread pattern,
In other words, the extending direction of the block is opposite to the cord direction of the outermost belt ply, and as a result, the lateral force based on the self-lining torque is offset by the lateral force generated by the tread pattern, improving the straight-line performance of the pneumatic tire. A tire with improved performance was proposed.

However, with pneumatic radial tires such as those mentioned above, the tread pattern attempts to eliminate the self-lining torque of the belt ply.
Since the lateral force caused by such a tread pattern is small, there is a problem in that the straight running performance cannot be sufficiently improved.

An object of the present invention is to provide a pneumatic radial tire that can reliably offset the self-lining torque generated by the cord of the outermost belt ply and dramatically improve straight running performance.

This purpose is to create a belt layer consisting of a carcass layer having a toroidal shape in which cords extending in the radial direction are embedded, and two or more belt plies arranged outside the carcass layer in the radial direction and having cords embedded therein. , a tread having a plurality of rows of blocks arranged on the outer surface in the radial direction of the belt layer and consisting of a large number of blocks spaced apart in the circumferential direction, and the cord embedded in the outermost belt ply, In a pneumatic radial tire that is inclined from one side in the width direction to the other side in the circumferential direction, the radius of each block in the block row located at at least one end in the width direction A straight line connecting the circumferential center point at the inner end in the direction and the circumferential center point at the outer end in the radial direction is inclined to one side in the circumferential direction as it goes radially outward with respect to the normal T of the tread, and at least in the width direction. The straight line M connecting the circumferential center point at the radially inner end and the circumferential center point at the radially outer end of each block of the block row located at the other end is the tread modulus! This can be achieved by inclining toward the other side in the circumferential direction toward the outside in the radial direction with respect to IT.

Here, as described in claim 2, the straight line of all the blocks of the block row located on one side in the width direction from the tire equatorial plane is aligned in the circumferential direction as it goes radially outward with respect to the normal T of the tread. At the same time, the straight line M of all the blocks in the block row located on the other side in the width direction from the tire equatorial plane is made to incline toward the other side in the circumferential direction as it goes radially outward with respect to the normal T of the tread. You can.

Assume that the pneumatic radial tire of this invention is traveling straight in January. At this time, the belt ply located within the ground contact area of the tire expands and contracts due to the force, but this expansion and contraction causes in-plane shearing deformation of the belt ply, and the shearing deformation, especially the shearing deformation of the outermost belt ply, The tread rubber is deformed and a self-lining torque is generated in the tire. Here, the cord embedded in the outermost belt ply is inclined from one side in the circumferential direction to the other side in the circumferential direction as it goes from one side in the width direction to the other side in the width direction when viewed from the rotation axis of the tire. Therefore, a self-lining torque acts on the tire in a counterclockwise direction when viewed from above. On the other hand, in this invention, among the blocks formed on the tread outer surface of the tire, the circumferential center point at the radially inner end and the radially outer end of each block of the block row located at at least one end in the width direction A straight line connecting the center point in the circumferential direction is inclined to one side in the circumferential direction as it goes radially outward with respect to the normal T of the tread,
A straight line M connecting the circumferential center point at the radially inner end and the circumferential center point at the radially outer end of each block of the block row located at least at the other end in the width direction is radially aligned with respect to the normal T of the tread. It is inclined toward the other side in the circumferential direction toward the outside. Therefore, when the block that is inclined toward one side in the circumferential direction receives a load from the tire,
The block deforms and becomes more inclined toward one side in the circumferential direction (for the tire, it becomes displaced toward the other side in the circumferential direction), while the block that is inclined toward the other side in the circumferential direction receives a load from the tire. Then, the tire deforms and the inclination toward the other side in the circumferential direction becomes even larger (for the tire, this is a displacement toward one side in the circumferential direction).

Here, the blocks that are inclined toward one side in the circumferential direction are the blocks of the block row located at least at one end in the width direction, while the blocks that are inclined toward the other side in the circumferential direction are at least Since the block is in the block row located at the other end in the width direction, clockwise torque is applied to the tire when viewed from above. In this way, the self-lining torque generated by the outermost belt ply and the torque applied by the inclined block are opposite torques, so they cancel each other out, improving the straight-line performance of the tire.

Furthermore, with the configuration as set forth in claim 2, a large number of blocks deform and apply a torque in the opposite direction to the self-lining torque to the tire, so that the straight-line performance of the tire is further improved.

Hereinafter, a first embodiment of the present invention will be described based on the drawings.

In Fig. 1.2, 1 is a pneumatic radial tire, and this tire 1 has a pair of beads 2, and a carcass layer 3 having a toroidal shape with both ends of the beads 2 folded back in the width direction. The carcass layer 3 is composed of at least one (one in this embodiment) carcass ply 5 in which a large number of cords 4 extending in the radial direction (meridian direction) are embedded. A belt layer 7 is disposed on the outside of the carcass layer 3 in the radial direction, and this belt layer 7 is constructed by laminating two or more belt plies (in this embodiment, two belt plies 8 and 9). There is. Multiple cords 10 inside each belt ply 8.9
．． 11 are buried respectively, and these codes 10.11
extend in opposite directions.

That is, the cord lO of the outermost belt ply 8 is inclined from one side in the circumferential direction to the other side in the circumferential direction as it goes from one side in the width direction to the other side in the width direction when viewed from the rotation axis of the tire 1. The cords 11 of the inner belt ply 9 are inclined from one side in the radial direction to the other side in the width direction, and from the other side in the circumferential direction to the one side in the circumferential direction. These cords 10, 11 intersect the tire equatorial plane 15 at an angle within a range of 15 degrees to 40 degrees. The tread 8 is a tread placed on the outside of the belt layer 7 in the radial direction, and a plurality of (four in this embodiment) main grooves 19 extending in the circumferential direction are formed on the outer surface of the tread 18. The main grooves 19 are arranged at approximately equal distances apart in the width direction.

Further, a plurality of lateral grooves 20 extending substantially in the width direction are formed on the outer surface of the tread 18, and these lateral grooves 20 are arranged at substantially equal distances in the circumferential direction.

As a result of (2), these main grooves 1 are formed on the outer surface of the tread 18.
9 and the lateral grooves 20 define a plurality of rows (five rows in this embodiment) of block rows 22 consisting of a large number of blocks 21 spaced apart in the circumferential direction. In this embodiment, among these block rows 22, at least a block row located at one end in the width direction (in this embodiment, not only the block row 22a located at one end in the width direction but also the tire equatorial plane
All block rows 22a located on one side in the width direction from 5,
22b) blocks 21a, 21
One circumferential side of b! ! 23 and the other side wall 24 in the circumferential direction are both inclined toward one side in the circumferential direction as shown in FIG. A straight line connecting the circumferential center point S in the tread 18 is inclined toward one side in the circumferential direction with respect to the normal T of the tread 18 as it goes radially outward. Also, among the block rows 22, at least the block row located at the other end in the width direction (in this embodiment, not only the block row 22e located at the other end in the width direction but also the row on the other side in the width direction from the tire equatorial plane 15) The one side wall 25 in the circumferential direction and the other side wall 26 in the circumferential direction of the blocks 21 d, 21 e constituting all the block rows 22 d, 22 e located in By making these blocks 21d
, a straight line M connecting the circumferential center point U at the radial inner end of e and the circumferential center point V at the radial outer end of It is tilted. Here, the straight line,
The intersection angle G between M and the normal T is preferably in the range of 5 degrees to 30 degrees, because if the intersection angle G is less than 5 degrees, the block 21a when subjected to the load of the tire 1,
This is because the amount of deformation of blocks 21a, d, and e is small and cannot sufficiently offset the self-lining torque caused by the outermost belt ply 8. On the other hand, if the deformation exceeds 30 degrees, the radial outer ends of blocks 21a, b, d, and e This is because an edge with a small angle is formed on the vehicle, and there is a risk that the edge may be damaged during running. Further, sipes 28 are formed in the blocks 21a1b and dSe, and these sipes 28 extend parallel to the straight line M.

Next, the operation of the first embodiment of the present invention will be explained.

Now, assume that tire 1 mentioned above is traveling straight. At this time, the belt ply 8.9 located within the ground contact area of the tire 1 expands and contracts under the force, but due to this expansion and contraction, the belt ply 8.9 undergoes in-plane shear deformation, and the shear deformation, especially at the maximum Shear deformation of outer belt ply 8 causes tread 1
8 to deform the tread 18,
generates self-lining torque. Here, the cord 10 embedded in the outermost belt ply 8 extends from one side in the circumferential direction to the other side in the circumferential direction as it goes from one side in the width direction to the other side in the width direction when viewed from above the rotation axis of the tire 1. Since the tire 1 is so inclined, a self-lining torque acts on the tire 1 in a counterclockwise direction when viewed from above. On the other hand, in this embodiment, among the blocks 21 formed on the outer surface of the tread 18 of the tire 1, the tire equatorial plane 1
Block rows 22a and 22b located on one side in the width direction from 5
The straight line in each block 21a1b of the tread 18
The straight line M in each block 21d, e of the block rows 22d, e located on the other side in the width direction from the tire equatorial plane 15 is inclined toward one side in the circumferential direction with respect to the normal T of the tread 18. It is inclined toward the other side in the circumferential direction with respect to T. Therefore, when the block 21a1b, which is inclined toward one side in the circumferential direction, receives a load from the tire 1, it is deformed and the inclination toward one side in the circumferential direction becomes even larger, while the block 21a1b is inclined toward the other side in the circumferential direction. The block 21dSe that is inclined towards the other side is similarly deformed and becomes even more inclined towards the other side in the circumferential direction. Here, since the outer ends in the radial direction of these blocks 21 albs ds e are in contact with the ground and cannot be displaced, the deformation of the blocks 21 aq b causes the tire 1 on one side in the width direction from the tire equatorial plane 15 to
is displaced to the other side in the circumferential direction, and the tire 1 on the other side in the width direction from the tire equatorial plane 15 is displaced to one side in the circumferential direction due to the deformation of blocks 21d and 21e. Therefore, clockwise torque is applied to the tire 1 as viewed from above due to the deformation of the block 21. Here, since the self-lining torque generated by the outermost belt ply 8 and the torque given by the deformation of the blocks 21a, b, d, and e are opposite torques, these torques cancel each other out, and the tire's This improves straight-line performance. Note that the torque applied to the tire 1 from the block 21 is the largest since the torque from the block 21a1e of the block row 22aSe located at one end in the width direction and the other end in the width direction farthest from the tire equatorial plane 15 is the largest. , only the blocks 21a and 21e at one end in the width direction and the other end in the width direction may be tilted as described above, but in this embodiment, the blocks 21b and d of the other block rows, that is, the block row 22b1d are also tilted. Similarly, the straight running performance of the tire 1 is further improved by tilting it.

FIG. 5 is a diagram showing a second embodiment of the invention. In this embodiment, one side wall 31 in the circumferential direction of the block 30 of the block row located at one end in the width direction is made parallel to the normal T of the tread 32, and the other side wall 33 in the circumferential direction is made parallel to the normal T. The block 30 is tilted to one side in the circumferential direction, so that the straight line of the block 30 is tilted to one side in the circumferential direction with respect to the normal T.

Although the blocks in the block row located at the other end in the width direction are not shown, they are inclined in the opposite direction to the blocks 30, that is, in the other side in the circumferential direction.

FIG. 6 is a diagram showing a third embodiment of the present invention. In this embodiment, one side wall 36 in the circumferential direction of the block 35 of the block row located at one end in the width direction and the other side W3 in the circumferential direction
7 are both made to protrude stepwise to one side in the circumferential direction, thereby making the straight line of the block 35 inclined to one side in the circumferential direction with respect to the normal T. Although the blocks in the block row located at the other end in the width direction are not shown, they are inclined in the opposite direction to the blocks 35, that is, in the other side in the circumferential direction.

Next, a test example will be explained. In this test example, a test tire having the block described in the first example (crossing angle G and sipe inclination angle are both 15 degrees) and a test tire having a crossing angle of 0 degrees, that is, one side wall in the circumferential direction and the other side wall in the circumferential direction. A comparative tire having blocks whose side walls were both parallel to the normal T was prepared. Here, the size of each tire is 195/65 R1
5, and the intersection angles of the cords embedded in the outermost belt ply with respect to the tire equatorial plane are both 22 degrees.0
Next, after filling each of these tires with an internal pressure of 2.2 kg/cm2, they were installed in a 2000 cc class passenger car, and while driving straight at 60 km/h, the tires were driven for 100 m with their hands off the steering wheel, and the 100 m journey was completed. The amount of deviation (m) at the time was measured. The result is
In the comparison tire, the vehicle deviated to the left by 1.1 m, but in the test tire, the amount of deviation to the left decreased to 0.1 m, and the straight-line performance was significantly improved.

As described above, according to the present invention, the self-lining torque generated by the cord of the outermost belt ply can be reliably offset, and the straight-line performance can be dramatically improved.

[Brief explanation of drawings]

FIG. 1 is a meridian sectional view showing a first embodiment of the present invention, FIG. 2 is a partially cutaway view taken along the X-X arrow in FIG. 1, and FIG. 3 is a Y-Y arrow sectional view in FIG. A cross-sectional view, Figure 4 is taken along Z-Z in Figure 2.
A sectional view taken in the direction of arrows, FIG.
FIG. 6 is a sectional view similar to FIG. 3 showing a third embodiment of the present invention. 3... Carcass layer 4... Cord 7... Belt layer 8.9... Belt ply 10.11.
...Code 18...Tread 21...Block 22...Block row R, U...Circumferential center point S, ■...Circumferential center point, M...Straight line T... Normal patent applicant Brideston Co., Ltd. Agent Patent attorney Ta 1) Toshio Diagram 3 Carcass layer 7 Belt layer 8.9 Belt ply 18, trend diagram other side in circumferential direction 4 Coat 10.11 Coat 21 Block 22 Block row Fig. Fig. Circumferential center, point Circumferential center point Line normal U Circumferential center point V Circumferential center 1 point M-Straight line Fig. 5 Fig. 6

Claims (2)

[Claims] (1) A carcass layer with a toroidal shape in which a cord extending in the radial direction is embedded, a belt layer consisting of two or more belt plies arranged on the radially outer side of the carcass layer and in which the cord is embedded, and a radial direction of the belt layer. a tread having a plurality of rows of blocks disposed on the outside and made up of a large number of blocks spaced apart in the circumferential direction on the outer surface, the cord embedded in the outermost belt ply is In a pneumatic radial tire that is inclined from one side in the circumferential direction toward the other side in the circumferential direction, the circumferential direction at the inner end in the radial direction of each block in the block row located at at least one end in the width direction The straight line L connecting the center point and the circumferential center point at the radially outer end is inclined toward one side in the circumferential direction as it goes radially outward with respect to the normal T of the tread, and is located at least at the other end in the width direction. A straight line M connecting the circumferential center point at the radially inner end of each block in the block row and the circumferential center point at the radially outer end of each block is drawn toward the other side in the circumferential direction as it goes radially outward with respect to the normal T of the tread. A pneumatic radial tire characterized by its slanted shape. (2) The straight line L of all the blocks in the block row located on one side in the width direction from the tire equatorial plane is inclined toward one side in the circumferential direction with respect to the normal T of the tread as it goes radially outward, and the tire equatorial plane 2. The pneumatic radial tire according to claim 1, wherein the straight line M of all the blocks in the block row located on the other side in the width direction is inclined toward the other side in the circumferential direction as it goes radially outward with respect to the normal T of the tread.