JPH0761210A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce a passing noise as operational stability and wet gripping performance are maintained by making a block pitch different among a plurality of block lines, and the block pitch in the inner block line larger in comparison with the outer block pitch. CONSTITUTION:When the numbers of blocks B1, B0 in an inner and an outer block line are shown by N1, N0, the width in a tire axial direction between the groove edges of a central main groove G1 by WG1, the width of in a tire axial direction between the groove edges of an outer main groove GO by WG2, the width of the inner block B1 by WBi, the grounding width of the outer block BO by WBo, the ratio of the peripheral pitch length Pgi, Pgo of an inner and an outer lateral groove gi, go to the width WBi, WBo of the block BI, BO by R1, Ro, and a half grounding width from a tire equator to an grounding end on one side by W, the following equations shall be satisfied, namely, 0.3<=Ni/No<=0.7, 0.1W<=WG1<=0.17W, 0.1W<=WG2<=0.17W, 0.3W<=WBi<=0.6W, 0.3<=WBo<=0.6W, 1.3<=Ri<=3.5, 0.5<=Ro<=1.2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of reducing passing noise while maintaining driving performance such as steering stability and wet grip performance in rainy weather.

[0002]

2. Description of the Related Art In recent years, along with the speeding up of vehicles accompanying the development of automobile technology, noise generated when the vehicle is running has increased, and it is required to suppress the noise.

In the tread portion of the tire, for example, as shown in FIG. 3, a plurality of vertical grooves a and b which are continuous in the tire circumferential direction.
And a large number of lateral grooves d and e arranged in a direction intersecting with the vertical grooves.
By forming the block pattern provided with, the rainwater between the tread surface and the road surface is eliminated through these grooves when running in the rain, and the wet grip performance is improved.

When a large number of such lateral grooves are provided, the compressed air between the tread surface and the road surface abruptly passes through the grooves during traveling, and this occurs intermittently, so that so-called pumping noise is generated. Occurs. Such noise is often generated in a block pattern tire having a large number of lateral grooves.

[0005]

In order to suppress such noise, there is also a device in which the groove cross-sectional area of the lateral groove is made small and the velocity of the air flowing through the lateral groove is reduced by bending the lateral groove. To do.

Although the noise is slightly reduced by these measures, the grip performance, particularly the wet grip performance, is deteriorated. In this case, uneven wear occurs on the groove wall of the lateral groove. However, there is a problem that the running performance and durability of the tire are deteriorated.

As a result of repeated studies to solve the above problems, the inventor (1) disperses the frequency of noise by changing the pitch of blocks between a plurality of block rows arranged in the circumferential direction, Noise reduction. (2) The cross-sectional area of the main groove extending in the circumferential direction is increased to improve drainage and maintain wet performance. (3) By increasing the block pitch in the inner block row compared to the outer block pitch, grip performance and braking performance are improved, while turning performance is achieved by making the blocks in the outer block row into a horizontally long shape. Increase.
Therefore, they have completed the present invention.

An object of the present invention is to provide a pneumatic tire capable of reducing passing noise while maintaining various running performances.

[0009]

According to the present invention, there is provided a central main groove having a straight groove edge on a tread surface passing through a tire equator,
By the outer main groove that passes through both sides and the groove edge on the tread surface is linear, a pair of ribs inside the center groove and the outer main groove facing each other, and the tread edge and this The inner ribs are divided into a pair of outer ribs between the groove edges of the outer main grooves facing each other, and the inner ribs intersect with the groove edges of the outer main groove to divide the inner ribs in the circumferential direction. The outer blocks are arranged in the circumferential direction by dividing the outer ribs by intersecting the inner lateral grooves forming the row of blocks in which the blocks are arranged and the groove edges of the outer main groove extending from and facing the tread edge. An outer lateral groove forming an outer block row is provided, the outer lateral groove intersects the groove edge of the outer main groove at an angle, and the inner lateral groove intersects the groove edge of the central main groove. While tilting in the opposite direction to the outer lateral groove, Number of racks: Ni Number of blocks outside the row of outer blocks: No Width in the tire axial direction between the groove edges of the main groove GI in the center: WG
1 Width in the tire axial direction between the groove edges of the outer main groove GO: WG2 Width of an inner block that is the length in the tire axial direction between the center main groove and the groove edges of the outer main groove: WBi Outside Width of the outer block, which is the length in the tire axial direction between the groove edge of the main groove on the side of the block and the ground contact edge: W
The ratio of the pitch length Pgi in the circumferential direction of the lateral groove gi in Bo to the width WBi of the inner block: Ri (= Pgi / WBi) The pitch length Pgo in the circumferential direction of the outer lateral groove go and the outer block Ratio with ground contact width WBo: Ro (= Pgo / WB
o) A half-width of ground contact from the tire equator to one ground contact end: When W, the pneumatic tire has the following relationship. 0.3 ≦ Ni / No ≦ 0.7 0.1W ≦ WG1 ≦ 0.17W 0.1W ≦ WG2 ≦ 0.17W 0.3W ≦ WBi ≦ 0.6W 0.3W ≦ WBo ≦ 0.6W 1.3 ≤ Ri ≤ 3.5 0.5 ≤ Ro ≤ 1.2

The inner block and the outer block may be provided with a narrow groove having a groove width of 0.01 to 0.07 times the ground contact half width W and extending linearly in the circumferential direction.

[0011]

The number of inner blocks Ni and the number of outer blocks No have the following relationship. 0.3 ≦ Ni / No ≦ 0.7

Therefore, when the tire is running, the sound range of the noise is deviated between the pumping sound generated from the inner block row and the pumping sound generated from the outer block row. Due to this deviation, the sound range of the noise emitted from the tire is diffused, and the annoying noise having a peak of 1000 peculiar to the pumping sound is dispersed to be alleviated and softened.

Further, by setting the ratio Ni / No within the above range, it is possible to separate the peak sound range of the noise generated from both the inner and outer block rows, and it is possible to eliminate the occurrence of a resonance sound such as a beat.

When the ratio Ni / No is less than 0.3, the circumferential length of the outer block becomes long, and the grip force, wet grip force in rainy weather, and wet braking performance are poor, while 0.7 is set. If it exceeds, the passing noise generated between the inner and outer blocks resonates, and the effect of noise suppression cannot be achieved.

The central and outer main grooves have a groove width WG.
By setting WG1 and WG2 in the range of 0.1 to 0.17 times the ground contact half width W, these main grooves ensure drainage. If it is less than 0.1 times, the drainage property is poor in rainy weather, and wet running performance such as wet grip performance and wet braking performance deteriorates, while if it exceeds 0.17 times,
As a result of the reduction of the actual ground contact area, the ground contact pressure increases, which accelerates the progress of wear of the tread surface and reduces the durability.

Further, the width WBi of the inner block and the ground width WBo of the outer block are both 0.3 to 0.6 times the ground half width W. This aims at equalizing the ground contact areas of the inner and outer blocks, and by making the ground contact areas between both block rows evenly close, the volume of noise generated between the block rows approaches and the sound is softened. Can be done. When either one of the blocks exceeds 0.3 times or exceeds 0.6 times, the balance of the noise amount generated from both block rows is lost, and the effect of reducing the noise and the effect of softening the sound are reduced.

Further, in the present invention, the ratio Ri = Pgi / WBi between the pitch length Pgi in the circumferential direction of the inner lateral groove gi and the width WBi of the inner block is set to 1.3 or more and 3.5 or less. Therefore, the inner block is formed as a vertically elongated block whose length in the circumferential direction is longer than its width. This enhances traction. When the ratio Ri is less than 1.3, the traction performance is reduced, and conversely, when it exceeds 3.5, the arrangement interval of the inner lateral grooves becomes long, and the drainage performance is reduced, so that the wet grip performance and the wet braking performance are reduced. Will be inferior to.

On the other hand, the ratio Ro = Pg of the pitch length Pgo in the circumferential direction of the outer lateral groove go to the ground contact width WBo of the outer block.
o / WBo is set to 0.5 or more and 1.2 times or less.
Therefore, the grounding surface of the outer block has a laterally long shape in which the length in the circumferential direction is shorter than the width dimension or a rectangular shape or a vertically long shape approximate to a rectangular shape. By setting the ground contact surface of the outer block to the above-mentioned ratio, it is possible to improve the running performance such as running stability and steering stability during turning. When the ratio Ri is less than 0.5, the traction performance when traveling straight ahead is poor, and when it exceeds 1.2, the kinetic performance during turning is deteriorated.

As described above, according to the present invention, the above-mentioned components are organically combined and integrated so that passing noise can be reduced while maintaining various running performances during dry and wet conditions.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Pass the tire equator C to the tread portion 2 and tread surface 2A
By providing the central main groove GI in which the groove edge 3 is linear and the outer main groove GO that passes both sides thereof and the groove edge 4 in the tread surface 2A is linear, the tread portion 2 is A pair of inner ribs RI, RI formed between the facing groove edges 3 and 4 of the central main groove GI and the outer main groove GO, a tread edge E, and a groove edge of the outer main groove GO facing the tread edge E. The outer ribs RO and RO are formed between the outer ribs RO and RO.

Further, in the inner rib RI, inner blocks BI ... Which are divided by intersecting the respective groove edges 3 and 4 of the central and outer main grooves GI and GO are arranged in the circumferential direction in an inner block row LI. Forming the inner lateral groove gi and the tread edge E
The outer rib RO is sectioned by intersecting with the groove edge 4 of the outer main groove GO that extends outward and faces the tread edge E, and the outer block BO forms an outer block row LO in which the outer blocks BO are arranged in the circumferential direction. A lateral groove go is provided.

Further, the pneumatic tire 1 has the tread portion 2
Has sidewall portions 13 and 13 extending inward in the tire radial direction, and bead portions 14 and 14 located at radially inner ends of the sidewall portions 13 and 13. Further, the pneumatic tire 1 includes a toroidal carcass 16 which is folded from the tread portion 2 through the sidewall portion 13 and around the bead core 15 of the bead portion 14, and a belt layer 17 of the tread portion 2 which is radially outside thereof. Get In this embodiment, a bead apex 18 is provided between the main body of the carcass 16 and the folded-back portion so as to rise radially outward from the bead core 15.

In the present embodiment, the carcass 16 is composed of one carcass ply, and the carcass ply has a carcass cord of 80 in this embodiment with respect to the equator C of the tire.
A sheet body of a so-called radial or semi-radial arrangement arranged at an angle of 90 ° to 90 ° and covered with a topping rubber is formed, and as a carcass cord, an organic fiber cord such as nylon, polyester, rayon or aromatic polyamide is adopted. It

In the present embodiment, the belt layer 17 is composed of two belt plies 17A and 17A. These belt plies 17A are made of nylon, polyester, rayon, aromatic polyamide or the like organic fiber cord or steel cord. Are arranged so that the plies cross each other.

In the pneumatic tire 1, a tread surface 2A has a ground contact surface which is wide when the tread surface 2A contacts the road surface when the tire 1 is in use. Here, this ground plane is defined as follows. The area in which the pneumatic tire 1 is attached to the standard ribs defined on the tire 1 and is in contact with the traveling road surface in the normal state where the normal internal pressure and the normal load are applied is defined as the ground area. Furthermore, in the ground area,
The distance between the tire equator C and the contact edge F, which is the edge farthest from the tire equator C in the tire axial direction in the peripheral edge surrounding the contact area, is defined as the contact half width W.

A width WG1 in the tire axial direction between the groove edges 3 and 3 of the central main groove GI facing each other is set to be 0.1 to 0.5 of the half-width W of the ground contact.
In the range of 0.17 times, the width WG2 in the tire axial direction between the groove edges 4 and 4 of the outer main groove GO facing each other is 0.1 to 0. The range is 17 times. However, the widths WG1 and WG2 do not necessarily have to have the same dimensions between the central and outer main grooves GI and GO. The groove depths of the central and outer main grooves GI and GO are preferably in the range of 0.12 to 0.2 times the ground contact half width.

The outer lateral groove go is a groove edge 4 of the outer main groove GO.
The angle θ1 on the acute angle side that intersects with the groove edge 4 while being inclined with respect to is formed as a straight groove having a range of 30 ° to 90 ° in the present embodiment.

Further, the outer lateral grooves go in the outer rib RO in parallel with each other in the circumferential direction at substantially equal pitches, in the same direction, and at the same inclination angle θ1.

Therefore, on the outer rib RO, the outer main groove G is formed.
A plurality of outer blocks BO ... Enclosed by O, two adjacent outer lateral grooves go, go, and the tread edge E are formed.

At the lateral cutting edge M where the inner lateral groove gi intersects the central main groove GL, it intersects the groove edge 3 of the central main groove GI, and the angle θ2 on the acute angle side is 15 to 15 in this embodiment.
The range is 70 °.

Such an inner lateral groove gi is the outer lateral groove go.
Of the inner ribs RI, and the inner ribs RI are arranged in the same direction at substantially equal pitches in the circumferential direction and at the same inclination angle θ2 with respect to the central main groove GI to form linear grooves.

Therefore, in the inner rib RI, the central main groove G is formed.
I, an outer main groove GO, and two adjacent inner lateral grooves gi,
A block BI ... Of a plurality of blocks surrounded by gi is formed.

The inner lateral groove gi is, in this embodiment, an adjacent inner block row L beyond the central main groove GI.
It has a break edge N that breaks in the block BI of I.

Further, the groove depths of the inner and outer lateral grooves gi, go are 0. 1 of the groove depths of the central and outer main grooves GI, GO.
It is preferably 7 to 1.0 times.

Further, the width WBi of the block BI in the above,
That is, the length in the tire axial direction between the groove edge 3 of the central main groove GI and the groove edge 4 of the outer main groove GO is 0.3 to 0.5 of the ground contact half width W.
In the range of 0.6 times, the ground width WB of the outer block BO
O, that is, the length in the tire axial direction between the groove edge 4 of the outer main groove GO and the ground contact edge F is set in the range of 0.3 to 0.6 times the contact half width W.

In the inner rib RI, the ratio Pgi / WBi = Ri of the pitch length Pgi in the circumferential direction of the inner lateral groove gi and the width WBi of the inner block BI is 1.3 to 3.5. The block BI within the range, and therefore the inner part, is formed as a block whose longitudinal direction is the circumferential direction. Further, in the outer rib RO, the pitch length Pgo in the circumferential direction of the outer lateral groove go and
Ratio Pgo / W of the outer block BO to the ground contact width WBo
Bo = Ro is in the range of 0.5 to 1.2, and therefore the shape of the ground plane of the outer block BO is formed to be laterally long in the circumferential direction or vertically long nearly square.

The ratio Ni / No of the number Ni of BIs in one inner block row LI to the number No of outer block BOs in one outer block row LO is as described above. Since it is provided every other go, the inner and outer blocks Bi and Bo are arranged with the ratio Ni / No being 0.3 or more and 0.7 or less.

Further, in the present embodiment, the above block B is used.
The I and the outer block BO are provided with thin grooves 6 and 7 extending linearly in the tire circumferential direction, respectively. It is preferable that the groove widths WG3 and WG4 of the narrow grooves 6 and 7 are in the range of 0.01 to 0.07 times the ground contact half width W. By providing such fine grooves 6 and 7, the drainage property of the tread surface is further improved, the wet running performance is improved, and
Even during dry running, the grip power of the blocks BI and BO is increased, and the traction performance and braking performance can be improved.

The groove widths WG3 and WG4 are the ground contact half width W.
Less than 0.01 times, the effect on drainage is not seen,
On the other hand, if it exceeds 0.07 times, the ground contact area of the blocks BI and BO is reduced, resulting in poor wear resistance.

[0040]

SPECIFIC EXAMPLE A tire (Example) having a tire size of 195/60 and having the configuration shown in FIGS.
The prototype was manufactured according to the specifications shown in Table 1, and the performance was tested. A tire having a conventional pattern shown in FIG. 3 (comparative example) was also tested to compare its performance.

[0041]

[Table 1]

The test method is as follows. 1) Passing noise A 1500cc class all-wheel-drive vehicle equipped with test tires was tested by a coasting test specified in JASO C606, and the passing speed was 60km on a straight test course.
/ H and coasting a distance of 50 m, passing noise by a stationary microphone installed at a distance of 7.5 m laterally from the running center line at a midpoint of the course and at a height of 1.2 m from the test road surface. Was measured and displayed as an index with the conventional example being 100. The higher the value, the lower the passing noise.

2) Brake performance Using the same vehicle as in 1), the vehicle is run on a test road surface at a speed of 60 km / H, and sudden braking is performed with a four-wheel lock to measure the braking distance until the vehicle stops. Then, the value is displayed as an index with the conventional example being 100. The larger the value, the better.

3) Turning performance Using the same vehicle as in 1), a curved road having a radius of 50 m was orbited and judged based on the required time and the driver's feeling, and displayed as an index with 100 as the conventional example. The larger the value, the better.

4) Wet performance Using the same vehicle as in 1), the speed is sequentially increased from speed 0 on a skid pad road with deep water of 5 mm, and the speed at the time when grip starts to occur is expressed as an index with Comparative Example 1 as 100. did. The larger the value, the better.

5) Steering stability The same vehicle as in 1) was used to run on the test course, and the judgment was made based on the driver's feeling. The larger the value, the better. The test results are shown in Table 2.

[0047]

[Table 2]

As a result of the test, it was confirmed that the noise of the embodiment is lower than that of the conventional example and the running performance is improved.

[0049]

As described above, the pneumatic tire of the present invention has the above-mentioned structure, and thereby it is possible to reduce passing noise while maintaining various running performances such as steering stability and wet grip performance. I can.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a developed plan view showing the tread pattern.

FIG. 3 is a developed plan view showing a tread pattern of a conventional tire.

[Explanation of symbols]

 2 tread portion 2A tread surface 3, 4 groove edge 6, 7 narrow groove block inside BI block outside BO C tire equator E tread edge F grounding edge GI central main groove main groove outside GO lateral groove inside gi outside Example of block in lateral groove LI Block row outside LO Pitch in lateral direction of lateral groove in Pgi Pgo circumferential pitch length of lateral groove in outside RI Rib inside RI Rib outside RO W Ground width Width of block in WBi WBo Outer ground contact width WG1 Width in the tire axial direction between the groove edges of the central main groove GI WG2 Width in the tire axial direction between the groove edges of the outer main groove GO

Claims (3)

[Claims] 1. A central main groove having a straight groove edge on the tread surface passing through the tire equator, and an outer main groove having a straight groove edge on the tread surface passing on both sides of the tire. A pair of inner ribs between facing groove edges of the main groove and the outer main groove, and a pair of outer ribs between tread edges and groove edges of the outer main groove facing the tread edge, and the inner rib By intersecting the groove edges of the central and outer main grooves to partition the inner rib to form an inner block row in which the inner blocks are lined up in the circumferential direction, and to extend from the tread edge and face the inner lateral groove. An outer lateral groove that divides the outer rib by intersecting the groove edge of the outer main groove to form an outer block row in which the outer block is lined up in the circumferential direction is provided, and the outer lateral groove is the outer main groove. The transverse groove in the groove intersects with the groove edge of the groove at an angle and is the groove edge of the central main groove. On the other hand, while tilting in the opposite direction to the outer lateral groove, the number of blocks in the inner block row: Ni, the number of blocks outside the outer block row: No, the edge of the central main groove GI Width in the tire axial direction: WG
1 Width in the tire axial direction between the groove edges of the outer main groove GO: WG2 Width of an inner block that is the length in the tire axial direction between the center main groove and the groove edges of the outer main groove: WBi Outside Width of the outer block, which is the length in the tire axial direction between the groove edge of the main groove on the side of the block and the ground contact edge: W
The ratio of the pitch length Pgi in the circumferential direction of the lateral groove gi in Bo to the width WBi of the inner block: Ri (= Pgi / WBi) The pitch length Pgo in the circumferential direction of the outer lateral groove go and the outer block Ratio with ground contact width WBo: Ro (= Pgo / WB
o) Half-width of ground contact from the tire equator to one ground contact end: When W, the pneumatic tire having the following relationship. 0.3 ≦ Ni / No ≦ 0.7 0.1W ≦ WG1 ≦ 0.17W 0.1W ≦ WG2 ≦ 0.17W 0.3W ≦ WBi ≦ 0.6W 0.3W ≦ WBo ≦ 0.6W 1.3 ≦ Ri ≦ 3.5 0.5 ≦ Ro ≦ 1.2 2. The pneumatic tire according to claim 1, wherein the inner lateral groove is interrupted within a block of adjacent inner block rows over the central main groove. 3. The inner block and the outer block extend in the tire circumferential direction and are 0.01 times to half the ground contact half width W to 0.
A pneumatic tire having a groove width of 07 times and a narrow groove extending linearly in the circumferential direction.