JPH0214905A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To aim at reduction in a pattern noise without entailing any damage to wet skid resistance by forming a land part row being partitioned by plural numbers of circumferential sub-grooves in space between circumferential main grooves at a 40-80% interval of tread grounded width, and forming a block therein via each of rectilinear small space tilting at 15-40 degrees in the circumferential direction. CONSTITUTION:There are provided with a pair of circumferential main grooves G1, G1' with a space equivalent to a width of 40-80% in a tread grounded zone T between paired sidewalls, and also there are provided with circumferential sub-grooves g1, g, g2, g1' g2' in a central zone C between these main grooves G1 and G1', forming a land part row there. A block is formed in each land part row via small space tilting grooves S1-S3 at 15-40 degrees to the circumferential direction. At time of running, on a ground plane, respective blocks being adjoined in the circumferential direction via these small space tilting grooves S1-S3 are connected with one another. Reduction in a pattern noise can be promoted by these blocks being connected on the ground plane without entailing any damage to a wet characteristic owing to these circumferential main grooves.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Field of Application) The present invention relates to an improvement in a pneumatic tire having a block pattern, and more particularly, to an improvement in pneumatic tires having a block pattern, and more particularly, to an improvement in pneumatic tires having a block pattern, and more particularly, to an improvement in pneumatic tires having a block pattern, and more particularly, to an improvement in pneumatic tires having a block pattern. The present invention relates to a pneumatic tire with reduced wear resistance and improved handling on dry road surfaces.

(Prior art) - Typical tire tread patterns include rib patterns, lug patterns, block patterns, and rib-lug patterns, among which a plurality of main grooves continuous in the circumferential direction of the tire and a diameter of the tire. A block pattern in which a block pattern is formed by a large number of slanted grooves extending in a direction slanted in the direction of the tire is often used as a tire particularly designed to improve high-speed durability.

FIG. 3 is a developed view showing the tread portion of a conventional block pattern tire. Within the ground contact width T of the tire tread, there are a pair of wide circumferential main grooves G, , G.

are provided parallel to the circumferential direction, and two narrow circumferential minor grooves gl, g-+ and two wide circumferential minor grooves g2, g-2 are provided between the main i/4G+ and G-. , 5 in Ryojo Sakama
Book land (block row) B+B2, B3, B-2, B″
1 is formed.

In addition, each block row Bl, B2, B3, B-2, a-
+ has a large number of blocks divided in the circumferential direction by inclined grooves sl, s2, s3, s-2, and S''1, respectively.

In the above-mentioned conventional pneumatic tires, in order to ensure wet skid resistance (drainage performance), the slope of the inclined grooves forming the block is changed, for example, to the circumferential main groove G,
, G-, are made larger than 40%, and the angle of inclination with respect to the tire circumferential direction is made relatively large.

(Problems to be Solved by the Invention) However, in the conventional block pattern tire shown in FIG. In some cases, it is desirable to reduce the angle of inclination of the inclined groove with respect to the circumferential direction, but this would result in the formation of an extremely acute angle in at least one part of the block.
The difference in rigidity between this acute angle part and other parts is 10
Since this acts as a disadvantageous factor for wear, there is a problem in that pattern noise cannot be sufficiently improved.

In addition, the main causes of tire pattern noise are block vibrations that occur when the block edge hits the tread and air vibrations when the tire is sloped. However, in consideration of wet skid resistance, the groove width of the sloped grooves is usually set to 3 to 6 degrees. This is also a disadvantageous factor for improving pattern noise.

Furthermore, if the number of inclined grooves is increased in order to improve wet performance, there is a problem in that handling performance on a dry road surface deteriorates.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional pneumatic tires having a block pattern.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to reduce pattern noise and improve wear resistance and dry road handling of pneumatic tires with block pattern treads without impairing their wet skid resistance. It is in.

[Structure of the Invention] (Means for Solving the Problems) Conventionally, it was thought that the slanted grooves forming the blocks were extremely effective in terms of wet skid resistance, but according to the studies of the present inventors, It was found that volume reduction in the circumferential main groove was dominant.

A pair of circumferential main grooves, which are wider than conventional tires, are arranged with an interval corresponding to 40 to 80%, particularly 50 to 70%, of the tread's contact width, and the area is divided into two main grooves. A plurality of sub-grooves are provided extending parallel to this, and the groove width of the inclined groove that forms the block together with these circumferential grooves is set to 0.4 to 0.4.
4 stops, can be set to a particularly narrow width of 0°7 to 3m, and by arranging this inclined groove at a small angle of 15 to 40 degrees, especially 20 to 35 degrees, to the circumferential direction, pattern noise is significantly reduced. We have discovered that it is possible, and have arrived at the present invention.

That is, the pneumatic tire of the present invention has a cylindrical tread located between a pair of annular sidewalls, which is provided with cylindrical treads extending in the circumferential direction and arranged at intervals corresponding to 40 to 80% of the ground contact width of the tread. A tire is provided with a central region and both side regions separated by a pair of circumferential main grooves, and a plurality of circumferential minor grooves extending substantially parallel to the circumferential main grooves in the central region; The land portion divided by the circumferential groove substantially divides a large number of blocks in the circumferential direction by linear inclined grooves having an angle range of 15 degrees to 40 degrees with respect to the circumferential direction of the tire, and the inclined grooves It is characterized by having such a degree of freedom that blocks adjacent in the circumferential direction come into contact with each other through this inclined groove in the ground contact surface during running.

(Function) The pneumatic tire of the present invention has a tread contact width of 40 to
The tread is divided into a central region and both side regions by a pair of wide circumferential main grooves extending in the circumferential direction and arranged with an interval corresponding to 80%, and the circumferential main groove is in the central region. A plurality of circumferential minor grooves are provided that extend substantially parallel to each other, and the land section divided by the circumferential grooves in the central region extends linearly at an angle of 15 degrees to 40 degrees with respect to the circumferential direction of the tire. The installation position of the circumferential main groove has been changed because a large number of blocks are substantially divided in the circumferential direction by providing a narrow inclined groove that allows circumferentially adjacent blocks to come into contact with each other in the contact surface when the tire is running. Not only does the widening not impede wet performance, but the land portions (pronk rows) have the function of substantially continuous ribs in the circumferential direction, which improves handling characteristics, especially grip strength, on dry road surfaces. Significantly improved.

In addition, when the tire load is transferred, the block vibrations that cause pattern noise are suppressed by adjacent blocks, so the clean air vibrations are also naturally eliminated, and the pattern noise is significantly reduced.

Furthermore, even if block vibration occurs, it is alleviated at the time of input when the tire is depressed, so even if the inclined groove is set at a small angle with respect to the circumferential direction, the difference in rigidity will cause [15 mm] to be induced. There's nothing to do.

Therefore, according to the pneumatic tire of the present invention, pattern noise can be reduced without impairing the tire's wet skid resistance, and its wear resistance and handling on dry roads are significantly improved. Added value can be further increased.

(Example) Hereinafter, examples of the pneumatic tire of the present invention will be described in detail according to the drawings.

Figure 1 shows the first example of the pneumatic tire of the present invention! j! FIG. 2 is a developed view of the tread portion in the second repair example.

In addition, although illustration of the tire other than the tread portion is omitted in the figure, the other portions have a well-known structure.

In the first embodiment shown in FIG. 1, the contact area of the tread portion of the tire (the area that contacts the ground during normal driving)
T is divided into a central area C, both side areas, and D- by a pair of circumferential main grooves G, G- (straight grooves in this embodiment) extending in the circumferential direction provided on both sides thereof. ing.

The axial width between the circumferential main grooves Gl and Gt is 40 to 80%, particularly 50 to 80%, of the contact area T or tread width.
The axial groove width of each circumferential main groove is usually as wide as 6 to 12 inches, thereby ensuring wet skid resistance.

Furthermore, between the circumferential main grooves Gl and G-, there are five relatively narrow circumferential sub-grooves g1 extending substantially parallel to these main grooves.
．． g2, g, g-2, g Six land areas (block rows) B+, B2, B3, B-3, B-2, B by I
-+, and each of these block rows is divided into a large number of blocks by inclined grooves s, , B2, B3, s-3, S-2, S-. In this embodiment, the width of the minor groove is slightly narrower than the width of the main groove, and the width of the four minor grooves g+, B2, g-2, and g-+ of the song is not less than the width of the inclined groove. Each slope 1s+, 32.33, S-3, S-2, S-1 forming a narrower block
The groove width is 0.4 to 4 nnn, especially 0.7 to 3 ram,
In addition, the width is narrow enough that adjacent blocks come into contact with each other within the ground contact surface when the tire runs.

Note that in this embodiment, the inclined grooves S2, B3, S-3,
s-2 is a linear arrangement with inclined grooves Sl and S-
1 is oriented in the direction intersecting the axially adjacent grooves B2 and s-2 and is offset in the circumferential direction. It can be applied to all sloped grooves.

However, each of these inclined grooves SI, S2, B3, S-3, s
-2, s-, if the groove width is too small or absent, flexibility in the circumferential direction during tire rotation will be impaired, which is not preferable.

In addition, each inclined groove sl, B2, B3, s-3, S-2, S
-+ defines a block edge no matter how narrow it is, and this edge causes a blow when stepping onto the road surface, so
Angle θ1, θ2, θ3, θ-3, with respect to the tire circumferential direction
The angles θ-2 and θ-1 are arranged to be 15 to 40 degrees, particularly 20 to 35 degrees, which are smaller than conventional angles, in order to reduce pattern noise.

Furthermore, each inclined groove St, S2, S3, S-3, S-2,
The depth of S-1 is the same as or slightly shallower than that of the circumferential main grooves Gl and cl, and the depth in the longitudinal direction may be the same or partially different.

In addition, no grooves are provided in the both side areas and D-, but linear grooves extending parallel to the main groove are provided, and the inclined grooves S1 and S-+ are provided with linear grooves extending parallel to the main groove.
For example, a relatively wide groove oriented along the flow of the tread can be provided between the main groove and the tread edge to block these areas.

With this configuration, it is possible to reduce the width of the inclined groove while ensuring good wet skid resistance, thereby reducing pattern noise and further improving wear resistance and handling in dry conditions. be able to.

Next, in the second embodiment shown in FIG. 2, the circumferential minor groove g2,
The difference from the first embodiment described above is that the groove width of g-2 is made slightly larger to further improve the 'vVET property.
In the second embodiment, pattern noise is similarly reduced, and wear resistance and handling on dry roads are improved.

Next, the structure and effects of the pneumatic tire of the present invention will be further explained by giving test examples.

(Test Example) The block pattern shown in FIGS. 1 to 3 described above was formed on the tread portion of a radial tire having a tire size of 205/60R15, and this tire was evaluated.

In addition, other structures of the tire and r! The A construction conditions were the same as for conventional tires, so details will be omitted.

That is, in FIG. 1, the groove width of the circumferential main grooves G1 and GM was set to 8 nodes, and the interval between the circumferential main grooves 01 and G''1 was set to 57% of the tread width T.

In addition, the circumferential minor grooves gI g2, g-2, g of the central area C
-t groove width is 2 nm, and the width of the sub-groove g is 61 m.The block rows Bl, B formed by these circumferential sub-grooves are
2. Set the axial width of B3, B-3, B-2, and B-+ to 12
11II.

The width of 7 circles of the inclined groove forming each block row is 51s2
, s-2, s-mouth 1.2 kaku, s3, s-3 0.7r
m, and the inclination angle of each inclined groove with respect to the circumferential direction is θ,
The tire (A) of the present invention was obtained by setting θ3, θ-3, and θ-1 to 30 degrees, and setting θ2 and θ-2 to 31 degrees.

In addition, as shown in FIG. 2, the tire of the present invention was manufactured in the same manner as described above except that the groove width of the circumferential minor grooves g2 and g2- was changed to 4 mm, and the groove width of the minor groove g was changed to 3 mm. (B) was obtained.

On the other hand, for comparison, as shown in FIG. 3, the groove width of the circumferential main grooves G, , G-, and
, the groove width of g″1 is 0.7 mm, the circumferential minor groove g2, the groove width of g-2 is 4 mm, the axial width of the block rows B, , B2, B-2, B-, is 12B, the block row The axial width of B3 is 16 nm,
The groove width of the inclined grooves S, S2, S-2, S-t is 5 am, the groove width of the inclined groove S3 is 0.7 am, the inclination angle of each inclined groove with respect to the circumferential direction θ1, θ2, θ3, θ゛2, 5 for each θ-1
A conventional tire was obtained in the same manner as the tire of the present invention, except that the angle was 5 degrees.

For these three types of tires, we evaluated the pattern noise index, hydrobraining rate index on wet roads (drainage index), handling index on dry road surfaces, and wear life index (life index) through actual vehicle feeling tests. Show to the corporation.

(The following is a margin) (The index is large) From the above results, the pneumatic tire of the present invention reduces pattern noise while ensuring good resistance to edging.
Furthermore, it is clear that the wear resistance and handling properties on dry roads are also excellent.

[Effects of the Invention] As described above in detail, the pneumatic tire of the present invention has a pair of tires extending in the circumferential direction and arranged with an interval corresponding to 40 to 80% of the ground contact width of the tread. The tread is divided into a central area and both side areas by a wide circumferential main groove, and the central area is provided with a plurality of circumferential minor grooves extending substantially parallel to the circumferential main groove; The land section divided by the directional groove extends linearly at an angle of 15 degrees to 40 degrees with respect to the circumferential direction of the tire, and the extent to which blocks adjacent in the circumferential direction within the contact surface contact each other when the tire is running. By providing narrow slanted grooves to substantially divide a large number of blocks in the circumferential direction, not only the wet skid resistance is not impaired due to the installation position and width mainly in the circumferential direction, but also the land portion (
By making the block rows substantially similar to ribs, the handling characteristics on dry roads, especially the grip, are significantly improved.

Further, when the tires are transferred, the block vibrations that cause pattern noise are mutually suppressed by adjacent blocks, so the air vibrations in the groove are also naturally eliminated, and the pattern noise is significantly reduced.

Furthermore, even if block vibration occurs, it is alleviated at the input point when the tire is depressed, so even if the inclined groove is set at a small angle with respect to the circumferential direction, uneven wear will be induced due to the difference in rigidity. There is no.

Therefore, according to the pneumatic tire of the present invention, pattern noise can be reduced without impairing the wet performance of the tire, and the 'fdl'J wear resistance and DRY handling performance are greatly improved, further enhancing its added value. can be increased.

[Brief explanation of the drawing]

Fig. 1 is a developed view of the 1 to red parts in the first embodiment of the pneumatic tire of the present invention, Fig. 2 is a developed view of the tread part in the second embodiment, and Fig. 3 is a developed view of a conventional pneumatic tire. It is a developed view of a tread part. T...Touching area C...Medium fire area, D-...Both sides Gl, G1...Circumferential direction 1 vortex g1, B
2, g... Circumferential side vortex B2-1gl -... ll B1, B2, B3... Block row B5-182'' B1-...〃 S1, B2 , B3...... Slanted groove 53
-1S2- Sl-... 2's agent Patent attorney
Yasuo Miyoshi

Claims (1)

[Claims] A cylindrical tread located between a pair of annular sidewalls is provided with a pair of circumferential main grooves extending in the circumferential direction and spaced apart from each other at intervals corresponding to 40 to 80% of the ground contact width of the tread. The tire is provided with a plurality of circumferential minor grooves extending substantially parallel to the circumferential main groove in the central area, the tire having a land area divided by the circumferential grooves in the central area. The section substantially divides a large number of blocks in the circumferential direction by linear inclined grooves having an angle range of 15 degrees to 40 degrees with respect to the circumferential direction of the tire, and the inclined grooves are arranged so that the inclined grooves are formed within the ground contact surface during running. A pneumatic tire characterized by having a groove width such that circumferentially adjacent blocks come into contact with each other through the groove.