JPS63301109A - Automobile tyre with excellent control stability - Google Patents

Abstract

PURPOSE:To enhance control stability by forming the length along auxiliary grooves which extend in such a way to cross with main grooves obliquely longer than the length along the main grooves which extend in the circumferential direction of a tyre in linear, in blocks formed in the tread of the tyre. CONSTITUTION:In the tread of a tyre, plural blocks 4 are formed with respective plural main grooves 1 and auxiliary grooves 2. The main grooves 1 are provided in linear along the circumferential direction of the tyre. In addition, the auxiliary grooves 2 are provided in linear or in curved form in S shape in the direction which crosses with the main grooves 1 obliquely. Further, the auxiliary grooves 2 are provided continuously at least from one ground end 3 of the tyre tread to the other ground 3'. In the above construction, in the blocks 4 the length along the auxiliary grooves 2 is longer than that along the main grooves 1. With this arrangement, the blocks 4 of the tyre are formed in optimal form when specific oblique force is added from ground surface at the time of turning of an automobile.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automobile tire with excellent handling stability, and more specifically, to a tire that exhibits optimal handling stability when mounted on a pair of left and right wheels respectively. The present invention relates to an automobile tire that uses a pair of tires having tread patterns that are plane symmetrical to each other so as to provide excellent performance.

[Traditional Shubuding]

Conventional automobiles use tires with the same tread pattern on all wheels.

For example, tires with main grooves parallel to the circumferential direction are often used on wet roads because they have good drainage and excellent wet skid performance. As shown in , they are provided in alternate directions for each lip. This tread pattern is non-directional and is used identically on all wheels.

Furthermore, tires are also used in which sub-grooves are provided in a symmetrical chevron shape with respect to the center plane of the tread, as shown in FIG.

(For example, JP-A No. 55-140604) This tread pattern has a directionality in the direction in which it is attached to the rim, but when attached to a car, it should be attached to the rim so that the chevrons of the minor grooves are in the same direction on all four wheels. It is used as

[Problem that the invention seeks to solve]

In order to improve the maneuverability of an automobile, especially when turning, it is necessary to correctly transmit the force that the tire's ground contact surface receives from the ground when turning to the rim.

When turning, a large centrifugal force is applied to the wheels on the outside in the turning direction.
As a reaction, it receives a centripetal force from the ground. Therefore, it is most rational to attach tires to each wheel with a tread pattern that is optimal for the force that the outer wheels receive from the ground when turning. As shown in Figure 4, the direction of the force that each wheel receives when it is on the outside when turning is diagonally to the right,
Or diagonally to the left.

However, conventional tires with tread patterns such as those shown in FIG. 2 or 3 are not optimally designed for specific diagonal forces for mounting on any wheel.

Therefore, an object of the present invention is to provide a tire having a tread pattern that is optimally shaped when a specific diagonal force is applied from the ground.

[Failure to solve intervening vertices]

As a result of repeated research by the present inventors to achieve the stated purpose, it was found that in order to improve the handling performance when a certain diagonal force is applied to the tire, it is necessary to form multilayer grooves in the tire tread. The present invention has been completed by discovering that by forming the block to extend in the direction of the force, deformation of the block due to the force in that direction can be reduced and maneuverability can be improved.

Next, the content of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a developed view of an example of the tread pattern of the tire of the present invention. (1) is a plurality of main grooves formed in a straight line along the circumferential direction of the tire, and is straight in a direction diagonally intersecting the main groove (1), or slightly curved in an S-shape. A large number of shaped sub-grooves (2) are provided at approximately constant intervals. Minor groove (
2) at least one ground contact edge (3) of the tire tread
The tread is continuously provided diagonally across the tread from the ground contact end (3)' to the other ground contact end (3)'. The length I4, which is the interval between adjacent main grooves measured along the minor groove, is also longer than the length LC, which is the interval between the minor grooves (2), which is measured along the major groove.

As a result, the block (4) formed surrounded by the main groove (1) and the sub-groove (2) has a shape that extends obliquely along the sub-groove (2).

The average slope θ of the sub groove (2) from one grounding end (3) to the other grounding end (3)' is given by -〇=TP10W (1
) (where CW is the ground contact width of the tread, and T'P is the length that the minor groove advances in the circumferential direction of the tire while reaching from one ground contact end to the other ground contact end), but is given by 0.4 ≦TP1
0W≦0.9 It is preferable to set it as the range of (2).

As shown in FIG. 5, when TP/CW is less than 0.4, the tire running noise increases, and when TP/CW is less than 0.4.
If it is larger than 9, the rigidity of the block will be reduced and the cornering power will be reduced.

The inclination of the sub-groove (2) is made so that the inclination of the part that contacts the outer block (AOl, kit) is smaller than the inclination of the part that contacts the inner block (AO2+A12), making the entire sub-groove almost S-shaped. It is desirable to form it into a gently curved line or into a broken line shape that approximates the curved line.

When the pitch of the sub-grooves (2) is constant, as the inclination of the sub-grooves increases, the shape of the block adjacent to it becomes elongated.
Block stiffness decreases. In order to increase the rigidity of the outer blocks, which are subject to a heavy load during turning, it is necessary to reduce the slope of the sub-grooves in the outer parts.

However, it is preferable that the difference 1An-An-11 between the minor grooves in the portions in contact with adjacent blocks be within 20'.

If the difference in inclination exceeds 200, there will be a large difference in rigidity between adjacent blocks, causing uneven wear.

Actual ground area of each block (-) B A 2.7XOW
≦BA≦6. OX CW -・-・-(3) (however, OW is the ground contact width (so-called)), and the actual ground contact area OBA (mJ) of the outermost block when tires are installed on the car is 8.0XCW<OBA≦6.0XcW -...
・-(4) is desirable.

As the ground contact area of the block increases, the cornering power increases as shown in Figure 6, but if the area becomes too large, the ground contact deteriorates and the cornering power no longer increases beyond a certain value, and on the contrary, the heel Abnormal wear such as tow becomes more likely to occur.

Also, it is preferable that the outermost blocks, which bear a large load when turning, are larger than the inner blocks. Therefore, the optimal area for the ground contact area of each block is determined depending on the size of the ground contact width, and the area within the above range (the area within the tread ground contact width)
C = 0.55≦CR≦0.75 (
If the impact area ratio C is smaller than 0.55, the maneuverability on dry road surfaces will deteriorate and the OR
When the ratio exceeds 0.75, wet skid performance deteriorates.

The developed view of the tread pattern of the tire of the present invention may be point symmetrical with respect to a point on the center line II of the tread, and may have no directionality in the direction in which it is mounted on the rim.
Instead of the point symmetry as described above, there may be a direction in which it is attached to the rim. For example, as shown in FIG. 9, the ground contact area on the outside can be increased asymmetrically.

If the above-mentioned symmetry does not exist, the difference in the actual ground contact area ratio on both sides of the center line II' of the tire tread is within 10%, and the contact area ratio C on the side to be installed on the outside of the rim. should not be smaller than the inner sudden contact area ratio C⇠i. That is, 0≦CRO−CRi≦0.1 −
・−・Make sure that it is within the range of (6).

As a means of improving steering stability when turning, it is possible to increase the ratio of the actual ground contact area outside the center of the tire, but if the difference is extremely large, the balance of mass and rigidity on both sides of the center of the tire will be lost, resulting in imbalance. Wear occurs, reducing tire life.

The width Gls...Gn of the main groove is such that the total width ΣG1 is 0.2<ΣG i / CW<0.3 with respect to the ground contact width CW.
It is preferable to set it within the range of (7).

When the ratio is less than 0.2, the drainage effect on wet road surfaces is rapidly reduced, causing hydroplaning. When it exceeds 0.3, the rigidity in the axle direction decreases, and the steering stability on dry road surfaces decreases. The situation is shown in FIG.

When manufacturing the tire of the present invention, the direction of inclination of the cords of the outermost steel belt is opposite to the direction of inclination of the minor grooves of the tread pattern 7, so that the steel cords and the minor grooves are at right angles as much as possible. By intersecting at an angle close to , it is possible to reduce plysteer, which is a factor that impedes the straightness of the vehicle. Plysteer is the measurement and processing of the average lateral forces fl and FD applied to the drum when the tire is pressed against the test drum under a constant load and rotated by changing the direction of rotation of the tire.

[Effect]

The tire of the present invention uses a pair of symmetrical tires in which the direction of inclination of the minor grooves is opposite to the center line ■■, and is a mirror image of each other. Attach one pair of tires to each. As shown in Figure 8a, b, and c, the mounting direction is such that the sub-groove (2) is oriented diagonally from the inner front of the rim to the outer rear in the footprint of the tire, and Sub-groove on driving wheels (2)
Attach it so that it faces from the front outside of the rim to the rear inside.

When turning, a large load is applied to the outer wheel of the turn, and the force that the outer tire receives from the ground is as shown in Fig. 4 when one rear wheel is driven, for example, and as shown in Fig. 8 a. When the tire of the present invention is installed on a tire, the direction of the force matches the direction of the sub-groove, and the force is applied in the longitudinal direction of the block, so the block has high rigidity in that direction, effectively supporting the force. This improves steering stability when turning.

[Example] As a tire of the present invention, a tire size 2 having a tread pattern shown in the developed view of FIG.
A running test was conducted using tires of 25150 VR16, which were mounted on a rear wheel drive vehicle in the arrangement shown in FIG. 8a. Tire pressure 2. Okq/d1 used rims 16X7J, test vehicle was rear wheel, drive vehicle. For comparison, the same test was conducted using a tire of the same size having a V-shaped minor groove as shown in FIG. 3, and a tire of the same size having a general tread pattern as shown in FIG.

The test was conducted on dry and wet roads to evaluate straight-line stability, turning performance, and lane change performance.

The results are shown in Table 1. These results were scored by the test driver for each test item, and expressed as an index, with the result of the tire with the conventional tread pattern shown in FIG. 2 set as 100. (The higher the index, the better the performance.) We also conducted tests on high-speed durability, rolling resistance, and ride comfort, but no differences were observed between the three types of tires listed above. .

Furthermore, on a wet road surface, pylons are installed at 35m intervals, and the limit speed when running slalom is expressed as an index.
Shown in the table.

(Leaving space below) Table 1 As shown in Table 1, when the tire of the present invention is installed, it shows superior results on both dry and wet roads compared to the conventional general tire shown in Figure 2. . Further, when the tire of the present invention is compared with the conventional tire having V-shaped minor grooves as shown in FIG. 3, they show almost the same performance on wet road surfaces, but the tire of the present invention shows superior results on dry road surfaces.

Furthermore, in the tire of the present invention, tests were conducted to see how the plysteer changes depending on the relationship between the direction of the cord of the steel belt and the direction of the trend sub-groove.

The tire of the present invention is arranged such that the direction of the cord of the outermost steel belt ply and the direction of the minor groove of the tread are inclined in opposite directions and intersect with each other at an angle close to a right angle; A tire in which the steel cord and the sub-groove are arranged so as to be inclined to the same side and intersect at a shallow angle, and for comparison, a tire and tread groove having an Ar-shaped sub-groove as shown in Fig. 3 were used. For tires with no pattern at all, calculate the LFD when rotating clockwise (CW) and counterclockwise (CCW), and calculate plysteer - Fs from this by Fs - 2 (LFD (cw) - LFE (ccw)) )−−(
8) K was calculated accordingly. The results are shown in Table 2. This test used tires with tire size 225150VR16, air pressure 2.0kg/d, load 470kq, and tire size 225150VR16.
Tests were conducted using X7J precision rims.

As shown in Table 2, if the direction of the cord of the outermost steel belt ply intersects the minor groove of the tread pattern at an angle close to a right angle, plysteer will be smaller and the straightness of the tire will be improved. .

Table 2 [Effects of the Invention] When the automobile tire of the present invention is used, the steering stability on dry and wet road surfaces is excellent, and especially the steering performance when turning is improved.

In addition, if the direction of the steel cords of the outermost steel belt ply and the direction of the minor grooves of the tread pattern are tilted in opposite directions and intersect at an angle close to a right angle, plysteer can be significantly reduced and the tire Improves straightness.

[Brief explanation of drawings]

Figure 1 is a developed view of the tread pattern of the automobile tire of the present invention, Figure 2 is a footprint diagram of the tread pattern of a conventional tire, and Figure 3 is a footprint diagram of the tread pattern of a conventional tire having chevron-shaped minor grooves. The printed diagram, Figure 4, is an explanatory diagram of the direction of the force that the contact surfaces of the tires receive from the ground when each tire is on the outside of the turn when turning in a rear-wheel drive vehicle.
Figure 6 is a graph showing the relationship between the average inclination of the minor groove of the tire of the present invention, noise level, and cornering power, Figure 6 is a graph showing the relationship between the actual ground contact area of the block and cornering power, and Figure 7 is a graph showing the relationship between the main groove Graphs showing the relationship between total width and maneuverability, Figures 8a, b, and c show the foot of each tire when the tire of the present invention is installed on a rear wheel, a real vehicle, a front wheel drive vehicle, a four wheel vehicle, and a drive vehicle, respectively. The print diagram, FIG. 9, is a developed view of the tread pattern of a tire according to another embodiment of the present invention. (1)...Main groove, (2)...Minor groove, (
3), (3)'...ground end, (4)...block. Patent Applicant Toyo Rubber Industries Co., Ltd. Agent Patent Attorney Yoshinoki Koyama Mebu Figure 2 Figure 3 Figure 4 Figure 5 Lower P/C * Figure 6 Block's literary talent or ILL style On trap BA ( Seats are now r fllllll

Inside I11.11

Claims (9)

[Claims] (1) The tread pattern includes a plurality of parallel linear main grooves extending in the circumferential direction of the tire, and a straight line that obliquely intersects the main grooves and extends continuously from one ground contact end of the tread to the other ground contact end. The length of the block formed by the main groove and the sub-groove is defined as the length of the block formed by the main groove and the sub-groove in the direction along the main groove. An automobile tire with excellent handling stability characterized by its shape being longer than its length. (2) The automobile tire according to claim 1, wherein the average slope θ of the sub-grooves from one ground contact end to the other ground contact end is in the range of 0.4≦tanθ≦0.9. . (3) The automobile tire according to claim 1, wherein the slope of the sub-groove is larger in the portion where the sub-groove contacts the block adjacent to the inner side than the portion where it contacts the outer block. (4) When the actual ground contact area of each block is BA (mm^2) and the ground contact width of the tread is CW (mm), BA is 2.
The automobile tire according to claim 1, which falls within the range of 7×CW≦BA≦60×CW. (5) Actual ground contact area O of the outermost block installed on the car
The automobile tire according to claim 4, wherein BA (mm^2) is larger than the actual ground contact area of the inner block, and OBA≧3.0CW. (6) The actual ground contact area ratio CR of the tread is 0.55≦CR
The automobile tire according to claim 1, which is in the range of ≦0.75. (7) Claims in which the difference in the actual ground contact area ratio on both sides of the center line II of the tire tread is within 10%, and the actual area ratio on the side that will be on the outside when mounted on an automobile is at least not smaller. The automobile tire according to item 1. (8) The ratio of the total width ΣGi of the main groove to the ground contact width CW of the tread is in the range of 0.2≦ΣGi/CW≦0.3. Automotive tires listed. (9) The direction of inclination of the steel cord of the outermost steel belt ply with respect to the tread center line is opposite to the direction of inclination of the minor groove of the tread pattern with respect to the tread center line, and the steel cord and the minor groove are close to a right angle. An automobile tire according to claim 1, wherein the tires are arranged so as to intersect at an angle.