JP2702878B2 - Pneumatic tire - Google Patents

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 various driving performances such as steering stability and wet grip performance in rainy weather.

[0002]

2. Description of the Related Art In recent years, as the speed of vehicles has increased due to the development of automobile technology, the noise generated by the vehicles during traveling has also increased, and suppression of the noise is required.

[0003] In a tread portion of a tire, for example, as shown in FIG.
And a number of horizontal grooves d, e arranged in a direction intersecting 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 during running on rainy weather, and the wet grip performance is enhanced.

When a large number of such lateral grooves are provided, the air compressed between the tread surface and the road surface suddenly passes through the grooves when the vehicle travels, and this occurs intermittently, so that a so-called pumping noise is generated. Occurs. Such noise is frequently seen in a tire having a block pattern provided with a large number of lateral grooves.

[0005]

Some measures have been taken to reduce the speed of the air flowing through the lateral groove by reducing the cross-sectional area of the lateral groove, for example, by bending the lateral groove in order to suppress such noise. I do.

[0006] Although noise is slightly reduced by these measures, grip performance, particularly wet grip performance, is reduced. In this case, uneven wear occurs on the groove wall of the lateral groove. For example, there is a problem that the running performance and durability of the tire are reduced.

As a result of repeated studies to solve the above problems, the inventor has found that (1) the frequency of noise is dispersed by changing the pitch of blocks among a plurality of block arrays arranged in the circumferential direction, To reduce noise. (2) The drainage is enhanced by increasing the cross-sectional area of the main groove extending in the circumferential direction, and the wet performance is maintained. (3) By increasing the block pitch in the inner block row as compared with the outer block pitch, grip performance and braking performance are improved, while turning performance is achieved by forming the blocks in the outer block row into a horizontally long shape. Enhance. (4) It has been found that by smoothly connecting the lateral grooves in the inner block row and the lateral grooves in the outer block row, drainage can be enhanced and noise generation can be further suppressed, and the present invention has been completed. is there.

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 which passes through a tire equator and has a straight groove edge on a tread surface;
A pair of ribs between the central main groove and the outer main groove facing the groove, and the tread edge, The inner rib is divided into a pair of outer ribs between the groove edges of the outer main groove facing each other, and the inner rib is divided into the center by crossing the groove edge of the outer main groove. The outer ribs are divided by intersecting the horizontal groove forming the block row in which the blocks are arranged and the groove edge of the outer main groove extending from the tread edge and facing the outer groove, and the outer blocks are arranged in the circumferential direction. An outer horizontal groove forming an outer block row, the outer horizontal groove intersects the groove edge of the outer main groove at an angle, and the inner horizontal groove is provided at every other outer horizontal groove. And each of the inner lateral grooves is adjacent to the outer lateral groove across the outer main groove and the outer lateral groove. The inner groove is smoothly continuous with the main groove, and the inner lateral groove has a bent portion which reverses in the circumferential direction in the rib in the inner groove. Tilt with respect to the groove edge of the main groove, the number of blocks in the inner block row: Ni The number of outer blocks in the outer block row: No Tire shaft between the groove edges of the central main groove GI Direction width: WG
1 Width in the tire axial direction between the groove edges of the outer main groove GO: WG2 Width of the inner block which is the length in the tire axial direction between the groove edge of the central main groove and the outer main groove: WBi Contact width of the outer block, which is the length in the tire axial direction between the groove edge of the outer main groove of the block and the contact edge, W
Ratio of the circumferential pitch length Pgi of the lateral groove gi in Bo to the width WBi of the inner block: Ri (= Pgi / WBi) The circumferential pitch length Pgo of the outer lateral groove go and the outer block Ratio to grounding width WBo: Ro (= Pgo / WB)
o) An acute angle at which the outer lateral groove intersects with the groove edge of the outer main groove: θ1 An acute angle at which the inner lateral groove intersects with the groove edge of the central main groove: θ2 One from the tire equator , The half-width of the ground to the ground end: W, the pneumatic tire has the following relationship. Ni / No = 0.5 0.1W ≦ WG1 ≦ 0.17W 0.1W ≦ WG2 ≦ 0.17W 0.3W ≦ WBi ≦ 0.6W 0.3W ≦ WBo ≦ 0.6W 1.3 ≦ Ri ≦ 3 0.5 0.5 ≦ Ro ≦ 1.2 30 ° ≦ θ1 ≦ 90 ° 15 ° ≦ θ2 ≦ 70 °

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 half ground width W and extending linearly in the circumferential direction.

[0011]

The following relationship exists between the number Ni of the inner blocks and the number No of the outer blocks. Ni / No = 0.5 In other words, the circumferential pitch of the inner lateral groove is の of the circumferential pitch of the outer lateral groove.

Therefore, during tire running, there is a shift in the sound range between the pumping sound generated from the inner block row and the pumping sound generated from the outer block row. Due to this shift, the range of the noise coming out of the tire is diffused, and the unpleasant noise peaking at 1000 which is peculiar to the pumping noise is mitigated and mitigated by dispersing.

Furthermore, by setting Ni / No = 0.5, the peak range of noise generated from both the inner and outer block trains can be separated, and the occurrence of resonance such as a beat can be eliminated.

Each of the center and outer main grooves has a groove width WG.
1. By setting WG2 in a range of 0.1 to 0.17 times the half width W of the ground, these main grooves ensure drainage. If it is less than 0.1 times, the drainage performance is inferior when running in rainy weather, and wet running performance such as wet grip performance and wet braking performance is reduced, while if it exceeds 0.17 times,
As a result of the decrease in the actual contact area, the contact pressure is increased, and the advancing speed of abrasion of the tread surface is increased to decrease the durability.

Further, the width WBi of the inner block and the ground width WBo of the outer block are both in the range of 0.3 to 0.6 times the half width W of the ground. This aims to equalize the grounding area of the inner and outer blocks, and to make the grounding area between both block rows even closer, so that the volume of noise generated between the block rows approaches each other and softens the sound. Can be done. When any one block is less than 0.3 times or more than 0.6 times, the balance of the noise amount generated from both block rows is disturbed, and the effect of lowering noise and the effect of softening sound are reduced.

Further, in the present invention, the ratio Ri = Pgi / WBi of the circumferential pitch length Pgi of the inner lateral groove gi to 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 long block whose circumferential length is longer than the width dimension. This increases traction. When the ratio Ri is less than 1.3, the traction performance is reduced. On the contrary, when the ratio Ri is more than 3.5, the arrangement interval of the internal horizontal grooves is increased, and the drainage performance is reduced, so that the wet grip performance and the wet braking performance are reduced. Inferior to

On the other hand, the ratio Ro = Pg between the circumferential pitch length Pgo of the outer lateral groove go and the ground 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 horizontally long shape or a vertically long shape approximating a square shape whose circumferential length is shorter than the width dimension. By setting the ground contact surface of the outer block to the above-described ratio, it is possible to improve running performance such as running stability and steering stability at the time of turning. When the ratio Ri is less than 0.5, the traction performance when traveling straight is poor, and when it exceeds 1.2, the exercise performance when turning is reduced.

The inner lateral groove gi is smoothly continuous with the outer lateral groove go adjacent to the outer lateral groove go with the outer main groove GO interposed therebetween. It has a bent portion that is reversed in the circumferential direction inside and crosses the rib inside.

By having such a bent portion that largely changes the direction, the flow of air flowing through the inner lateral groove is reduced at the bent portion, so that the generation of passing noise caused by the lateral groove is suppressed. Can be done. On the other hand, the inner lateral groove gi is smoothly continuous with the outer lateral groove go,
The rainwater flowing through the inner lateral groove gi can flow into the outer lateral groove go, and can be efficiently discharged from the outer lateral groove go toward the outside of the tire.

Moreover, since the angle θ2 on the acute angle side where the inner lateral groove gi intersects with the groove edge of the central main groove GI is set to 15 to 70 °, the central main groove GI side of the inner lateral groove gi is positioned on the tire rotation direction side. By mounting it toward, the rainwater of the rib RI, which has the highest contact pressure, can efficiently flow, so that the occurrence of hydroplaning during wet can be prevented, and the running stability and braking performance during wet can be reduced. Enhance. When the value of the angle θ2 is less than 15 °, the corner of the block BI formed by the central main groove GI and the inner lateral groove gi becomes sharp, and uneven wear tends to occur at the acute angle, and the value of the angle θ2 is 70 °. When the angle exceeds °, the ability of the inner lateral groove gi to collect rainwater is reduced, and the drainage is inferior.

Further, the angle θ1 on the acute angle side where the outer lateral groove go intersects the groove edge of the outer main groove GO is set to 30 to 90 °.
As a result, rainwater flowing from the outer lateral groove go and the inner lateral groove gi can be efficiently discharged toward both sides in the tire axial direction, and wet performance is enhanced. θ1 is less than 30 ° or 9
If it is larger than 0 °, the drainage performance due to the outer lateral groove go is reduced, and the wet performance is reduced.

As described above, according to the present invention, since the above-mentioned components are organically combined and integrated, the passing noise can be reduced while maintaining various traveling performances in the dry and wet states.

[0023]

An embodiment of the present invention will be described below with reference to the drawings. Tread surface 2A passing through tire equator C on tread 2
By providing a central main groove GI in which the groove edge 3 is straight, and an outer main groove GO in which the groove edge 4 in the tread surface 2A passes straight on both sides of the tread portion 2, A pair of inner ribs RI, RI formed between the groove edges 3, 4 of the central main groove GI and the outer main groove GO facing each other, a tread edge E and a groove edge of the outer main groove GO facing the same. 4 and a pair of outer ribs RO, RO formed between them.

Furthermore, the inner ribs RI are provided with inner blocks BI, which are divided by crossing the respective groove edges 3, 4 of the central and outer main grooves GI, GO, and are arranged in the circumferential direction. And the tread edge E
The outer ribs RO are separated from each other by intersecting the groove edges 4 of the outer main grooves GO which extend from the outer grooves RO and face the tread edges E, and form outer block rows LO in which outer blocks BO are arranged in the circumferential direction. A lateral groove go is provided.

The pneumatic tire 1 is provided with the tread 2
And sidewall portions 13 extending radially inward from both ends of the tire, and bead portions 14 located at radially inner ends of the sidewall portions 13. Further, the pneumatic tire 1 includes a toroidal carcass 16 that turns 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 on the outer side in the radial direction. I can. In this embodiment, a bead apex 18 is provided between the main body of the carcass 16 and the folded 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.
It is arranged at an angle of ° to 90 ° and forms a sheet of so-called radial or semi-radial arrangement covered with topping rubber, and an organic fiber cord such as nylon, polyester, rayon, aromatic polyamide is adopted as a carcass cord. You.

In this embodiment, the belt layer 17 is composed of two belt plies 17A, 17A. These belt plies 17A are made of an organic fiber cord such as nylon, polyester, rayon, aromatic polyamide, or a steel cord. Are arranged in a direction crossing each other between the plies.

In the pneumatic tire 1, when the tire 1 is in use, a tread surface 2A is formed to have a widened contact surface when the tread surface 2A contacts the road surface. Here, this ground plane is defined as follows. In a normal state where the pneumatic tire 1 is mounted on a standard rib defined for the tire 1 and a normal internal pressure and a normal load are applied, the area where the pneumatic tire 1 comes into contact with the running road surface is defined as a ground contact area. Further, in the ground area,
The distance between the contact edge F, which is the edge farthest in the tire axial direction from the tire equator C in the peripheral edge surrounding the contact area, and the tire equator C is defined as the contact half width W.

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

The outer lateral groove go is a groove edge 4 of the outer main groove GO.
At an acute angle side that intersects with the groove edge 4 at an angle of 30 ° to 90 °.

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

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

The inner horizontal groove gi is smoothly continuous with the outer horizontal groove go adjacent to the outer main groove GO via the outer main groove GO.
Is a bent portion 5 that is reversed in the circumferential direction in the inner rib RI.
And crosses the inner rib RI.

At the crossing edge M where the inner transverse groove gi intersects the central main groove GL, it intersects with the groove edge 3 of the central main groove GI, and the acute-angle angle θ2 is set in the range of 15 to 70 °. I have.

The inner lateral groove gi is connected to the outer lateral groove go.
Are arranged at substantially the same pitch in the circumferential direction in the inner ribs RI and at the same inclination angle θ2 with respect to the central main groove GI.

Therefore, the inner rib RI has a central main groove G
I, outer main groove GO, and two adjacent inner lateral grooves gi,
are formed among a plurality of blocks BI surrounded by gi.

In the present embodiment, the inner horizontal groove gi is formed so that the inner row of blocks L adjacent to the center main groove GI is over.
It has a break N that breaks in the block BI of I.

The groove depths of the inner and outer lateral grooves gi and go are set to be equal to the groove depths of the central and outer main grooves GI and 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 set to be 0.3 to less than the ground 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 a range of 0.3 to 0.6 times the contact half width W.

For the inner rib RI, the ratio Pgi / WBi = Ri between the circumferential pitch length Pgi of the inner lateral groove gi and the width WBi of the inner block BI is set to 1.3 to 3.5. The blocks BI in the range, and thus in the interior, are formed as blocks whose length is in the circumferential direction. Further, in the outer rib RO, a circumferential pitch length Pgo of the outer lateral groove go is represented by:
Ratio Pgo / W of the outer block BO to the ground width WBo
Bo = Ro is in the range of 0.5 to 1.2, and therefore, the shape of the grounding surface of the outer block BO is formed to be horizontally long or vertically long in the circumferential direction.

The ratio Ni / No of the number Ni of the BIs in one of the block rows LI to the number No of the outer blocks BO in the one outer block row LO is as described above. Since every other go is provided, inner and outer blocks Bi and Bo are arranged with the ratio Ni / No = 0.5.

Further, in this embodiment, the block B
I and the outer block BO are provided with narrow grooves 6 and 7 extending linearly in the tire circumferential direction. The width WG3, WG4 of each of these narrow grooves 6, 7 is preferably in the range of 0.01 to 0.07 times the half width W of the ground. By providing such narrow grooves 6 and 7, drainability of the tread surface is further improved, and wet running performance is enhanced.
Even during dry running, the grip force of the blocks BI and BO is increased, and traction performance and braking performance can be improved.

The groove widths WG3 and WG4 are equal to the ground half width W.
If 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 inferior wear resistance.

[0044]

[Specific Example] For a tire (example) having a tire size of 195/60 and having a configuration shown in FIGS.
A prototype was manufactured according to the specifications shown in Table 1, and its performance was tested. A test was also performed on a tire having the conventional pattern shown in FIG. 3 (comparative example), and the performance was compared.

[0045]

[Table 1]

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

2) Brake performance Using the same vehicle as in the item 1), the vehicle was driven on the test road surface at a speed of 60 km / H, and the braking distance was measured until the vehicle was stopped by suddenly braking with the four-wheel lock. The index is represented by an index with the conventional example being 100. The higher the value, the better.

3) Turning performance Using the same vehicle as in the item 1), the vehicle made a round on a curved road having a radius of 50 m. The required time and the driver's feeling were used to determine the turning performance. The higher the value, the better.

4) Wet performance Using the same vehicle as in 1), the speed is gradually increased on the skid pad road with a depth of 5 mm from the speed 0 from the speed 0, and the speed at which the grip starts to be generated is indicated by an index with the comparative example 1 being 100. did. The higher the value, the better.

5) Driving Stability The test vehicle was run on the test course using the same vehicle as in 1), and the evaluation was made based on the driver's feeling. The higher the value, the better. Table 2 shows the test results.

[0051]

[Table 2]

As a result of the test, it was confirmed that the example of the present invention reduced the passing noise and improved the running performance as compared with the conventional example.

[0053]

As described above, the pneumatic tire of the present invention having the above-described structure can reduce passing noise while maintaining various driving performances such as steering stability and wet grip performance. I can do it.

[Brief description of the 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 5 Bending portion 6, 7 Block inside narrow groove BI Block outside BO C Tire equator E Tread edge F Grounding edge GI Central main groove GO External main groove gi Horizontal groove inside gi gi Example of block inside lateral groove LI Block block row outside LO Circumferential pitch length of lateral groove inside Pgi Pitch circumferential pitch length of lateral groove outside Pgo Ri inside rib RO Outside rib W Ground half width Inside WBi Width of block WBo Grounding width of block outside WG1 Width in axial direction of tire between groove edges of central main groove GI WG2 Width of tire in axial direction between groove edges of main groove GO outside θ1 Outside lateral groove outside main groove The acute angle at which the transverse groove within the groove θ2 intersects the groove edge of the central main groove.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-136908 (JP, A) JP-A-4-201610 (JP, A) JP-A-63-49505 (JP, A) JP-A-63- 82805 (JP, A) JP-A-1-314610 (JP, A) JP-A-3-157207 (JP, A) JP-A-60-15204 (JP, A) JP-A-4-317805 (JP, A) JP-A-4-208605 (JP, A) JP-A-5-24415 (JP, A) JP-B 5-80362 (JP, B2) JP-B 4-29565 (JP, B2)

Claims (4)

(57) [Claims] 1. A central main groove passing through the tire equator and having a straight groove edge on the tread surface, and an outer main groove passing on both sides thereof and having a straight groove edge on the tread surface. A pair of inner ribs between the facing groove edges of the main groove and the outer main groove, and a pair of outer ribs between the tread edge and the groove edge of the outer main groove facing the same; The inner and outer grooves formed by crossing the groove edges of the central and outer main grooves to form an inner block row in which the inner blocks are lined up in the circumferential direction, and extending from and facing the tread edge. An outer lateral groove is formed by intersecting the groove edge of the outer main groove to divide the outer rib and form an outer block row in which outer blocks are lined up in the circumferential direction. The inner lateral groove is one of the outer lateral grooves, while obliquely intersecting the groove edge of the groove. And the inner lateral grooves are smoothly continuous with the outer lateral groove adjacent to the outer main groove and the outer main groove therebetween, and the inner lateral groove is formed within the rib therein. It has a bent portion that reverses in the circumferential direction and crosses the inner rib, and the crossed end is inclined with respect to the groove edge of the central main groove, and the number of blocks in the inner block row : No. Number of blocks outside the outer block row: No. Width in the tire axial direction between groove edges of the center main groove GI: WG
1 Width in the tire axial direction between the groove edges of the outer main groove GO: WG2 Width of the inner block which is the length in the tire axial direction between the groove edge of the central main groove and the outer main groove: WBi Contact width of the outer block, which is the length in the tire axial direction between the groove edge of the outer main groove of the block and the contact edge, W
Ratio of the circumferential pitch length Pgi of the lateral groove gi in Bo to the width WBi of the inner block: Ri (= Pgi / WBi) The circumferential pitch length Pgo of the outer lateral groove go and the outer block Ratio to grounding width WBo: Ro (= Pgo / WB)
o) An acute angle at which the outer lateral groove intersects with the groove edge of the outer main groove: θ1 An acute angle at which the inner lateral groove intersects with the groove edge of the central main groove: θ2 One from the tire equator , The half width of the ground up to the grounding end: W, the pneumatic tire having the following relationship. Ni / No = 0.5 0.1W ≦ WG1 ≦ 0.17W 0.1W ≦ WG2 ≦ 0.17W 0.3W ≦ WBi ≦ 0.6W 0.3W ≦ WBo ≦ 0.6W 1.3 ≦ Ri ≦ 3 0.5 0.5 ≦ Ro ≦ 1.2 30 ° ≦ θ1 ≦ 90 ° 15 ° ≦ θ2 ≦ 70 ° 2. The pneumatic tire according to claim 1, wherein said inner lateral groove is interrupted in a block of an adjacent inner row of blocks extending over a central main groove. 3. The pneumatic tire according to claim 1, wherein the outer lateral grooves extend from the tread edges on both sides in the same direction and at the same inclination angle in parallel with each other. 4. The inner block and the outer block extend in the tire circumferential direction and have a width of 0.01 to 0.1 times the half width W of the ground contact.
4. The pneumatic tire according to claim 1, wherein the pneumatic tire has a narrow groove having a groove width of 07 times and extending linearly in the circumferential direction.