JPH05169920A - Tire - Google Patents

Abstract

PURPOSE:To reduce transition noise without lowering wet braking performance. CONSTITUTION:A rib-patterned tire has the tread 2 provided with linear vertical grooves G. At least five vertical grooves G provided in the grounding area S of the tread 2 have the ratio SIGMAGW/SW of the sum SIGMAGW of the groove width GW to the grounding width in the grounding area being 0.12-0.16, with at least three vertical grooves G in which noise-proof pieces 6 with the lower faces located above the bottoms of the vertical grooves and protruded in a staggered manner from both groove walls into the vertical grooves, alternately, are formed on both groove walls with the vertical grooves between. The number of the noise-proof pieces 6 are four or more and six or less for each of vertical grooves G in the grounding area S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention regulates the number of vertical grooves extending in the circumferential direction of a tread surface and the total width of the grooves, and by providing a soundproof piece in the vertical grooves, the wet braking performance is not lowered. The present invention relates to a tire that can reduce passing noise.

[0002]

2. Description of the Related Art A tire has a plurality of longitudinal grooves extending in the tire circumferential direction on its tread surface. Such a groove discharges water adhering to the tread surface, closes the contact between the tread surface and the road surface, and increases the frictional resistance between the surfaces, thereby improving braking performance in rainy weather, that is, wet braking performance. Such an effect is particularly remarkable during high-speed running, and in recent years, high wet performance has been required for tires as the speed of vehicles increases.

On the other hand, when the vertical groove is formed, air column resonance sound generated when air compressed between the tread surface and the road surface is rapidly discharged through the columnar vertical groove during traveling, a so-called so-called columnar resonance sound. Air pumping noise increases tire passing noise. As the performance and sophistication of vehicles have increased, tires have been required to have less noise in addition to improved wet braking performance.

[0004]

In order to reduce the passing noise, straightening of the vertical grooves, reduction of the number of grooves and reduction of the groove volume have been carried out. However, these measures reduce the passing noise. However, it is inferior in other running performance, especially in wet braking property, and the appearance of the tire at the end of wear is inferior, so that it is replaced early and it is not preferable in terms of tire life. As described above, promotion of noise reduction and improvement of wet braking performance are in a trade-off relationship.

As a result of intensive studies by the inventors to improve the balance between reduction of passing noise and wet braking performance, the inventors have increased the number of vertical grooves arranged in the ground contact area as compared with a normal tire. To reduce the groove width per vertical groove and regulate the total width of the groove, in order to prevent the sudden outflow of air from the vertical groove that causes air column noise on the groove wall surface. The inventors have completed the present invention by finding that by providing a soundproof piece in the vertical groove, the passing noise of the tire can be reduced without lowering the wet braking performance.

An object of the present invention is to provide a tire capable of reducing the passing noise of the tire while maintaining the wet braking property.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a tire having a rib pattern in which a tread surface is provided with straight vertical grooves extending in the tire circumferential direction, the tire being mounted on a standard rim and having a normal internal pressure and a normal load. A groove width ratio ΣGW / SW of at least five and a total width ΣGW of the groove widths GW and a ground width, which is the width in the tire axial direction of the ground area, is 0.12 or more in the ground area in the normal state when the ground area is added. And at least three vertical grooves are provided on both groove walls sandwiching the vertical groove, the lower surface of which is located above the groove bottom of the vertical groove and within the vertical groove. The tire is characterized by forming soundproofing pieces alternately projecting from both groove walls in a zigzag manner, and setting the number of soundproofing pieces to 4 or more and 6 or less in each vertical groove of the ground contact area.

[0008]

[Function] Since the vertical grooves extend straight and more than five are arranged in the grounding area, rainwater adhering to the ribs between the vertical grooves can be effectively guided to the vertical grooves and the rainwater in the vertical grooves can be efficiently discharged. The wet braking force can be maintained by this.

The groove width ratio ΣGW / SW is set to 0.12 or more and 0.16 or less. In this way, by making the total sum ΣGW of the groove width GW smaller than the normal one, it is possible to reduce the total cross-sectional area of the air column formed by the vertical groove and the ground during traveling, and mainly the air pumping noise. Passing noise can be reduced. When the groove width ratio ΣGW / SW is less than 0.12, the drainage property is poor and the wet braking property is deteriorated.
If the ratio exceeds 0.16, reduction of passing noise cannot be achieved.

At least three of the vertical grooves located in the ground contact area are provided with soundproofing pieces alternately projecting in a zigzag pattern on both groove walls sandwiching the vertical groove. By providing such a soundproof piece, the air outflow speed from the vertical groove at the time of tire contact with the ground is reduced, and by providing the soundproof piece in a staggered manner, the airflow is made wavy and the outflow speed is reduced. The air pumping noise can be reduced.

It should be noted that if there are less than four soundproof pieces arranged in each vertical groove in the grounding area, the noise suppressing effect is small, and even if more than six soundproofing pieces are provided, the noise hardly changes. On the contrary, the drainage from the vertical groove becomes poor, and the wet braking performance deteriorates.

The bottom surface of the soundproof piece is located above the groove width of the vertical groove. This prevents the occurrence of cracks from the bottom of the groove where cracks tend to occur most in the tread portion, and ensures drainage even when the groove depth becomes shallow due to abrasion of the tread surface. This is to maintain the wet braking performance.

As described above, according to the present invention, since the above-mentioned constitutions are organically combined and integrated, the passing noise can be reduced without lowering the wet braking performance.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 4, a tire 1 is a tire having a rib pattern in which a plurality of vertical grooves G extending in the tire circumferential direction are provided on a tread surface 2, and each of the vertical grooves G ... Is formed as a straight linear groove. ..

The tire 1 has a tread portion 12 having the tread surface 2 as an outer peripheral surface, a sidewall portion 13 extending from both ends thereof inward in the tire radial direction, and an inner end of the sidewall portion 13 in the tire radial direction. It is formed as a pneumatic tire having a bead portion 14 located therein. or,
In the tire 1, a carcass 16 is formed by folding the bead core 15 of the bead portion 14 from the tread portion 12 through the sidewall portion 13 toward the outer side in the tire axial direction, and inside the tread portion 12 and radially outside the carcass 16. And a belt layer 17 disposed on the.

The carcass 16 comprises at least one carcass ply having a radial or semi-radial carcass cord inclined at an angle of 70 to 90 ° with respect to the tire equator C, and in this embodiment, one carcass ply. In addition to steel cords, organic fiber cords such as nylon and polyester aromatic polyamide are used as carcass cords.

In the present embodiment, the belt layer 17 is composed of four belt plies, and each belt ply is made of an organic fiber such as nylon, polyester, aromatic polyamide or a steel cord, and is inclined with respect to the tire equator C. And they are installed side by side.

On the tread surface 2, a tire 1 is mounted on a standard rim J, and a grounding area S for grounding when a normal internal pressure and a normal load are applied is virtually set, and in the grounding area S, Central vertical groove G on tire equator C
1, arranged on both sides in the tire axial direction of the central longitudinal groove G1 1
Five vertical grooves G are arranged, which are a pair of intermediate vertical grooves G2, G2 and a pair of external vertical grooves G3, G3 arranged on the outer side of each intermediate vertical groove G2 in the tire axial direction.

The groove widths WG of the central vertical groove G1, the intermediate vertical groove G2, and the outer vertical groove in the tire axial direction are slightly different in this embodiment. Groove width WG of the central vertical groove G1
1, the groove width WG2 of the middle vertical groove, the groove width WG of the outer vertical groove G3
The sum ΣGW of the groove widths GW, which is the sum of the groove widths GW, and ΣGW = WG1 + 2 × WG2 + 2 × WG3, and the groove width ratio ΣGW / SW, which is the ratio of the contact width SW forming the width in the tire axial direction in the contact area S. It is set to 0.12 or more and 0.16.

The central, middle and outer vertical grooves G1, G2,
The groove width GW of G3 may be formed to have the same groove width. Further, the groove depth GH of each of the vertical grooves G1, G2, G3 is the ground width S
It is preferably in the range of 0.05 times or more and 0.16 times or less of W.

The central vertical groove G1 and the intermediate vertical grooves G2, G
2 and the outer vertical grooves G3, G3, as shown in FIGS. 3 and 4, on both groove walls 4, 5 sandwiching these vertical grooves G1, G2, G3 from the groove walls 4, 5 and the groove wall 4, A soundproof piece 6 that projects in a direction substantially orthogonal to 5 projects.

The protrusion length L of the soundproof piece 6 from the opening edge F of the mounting groove wall 4 to the tip thereof is preferably not less than 0.25 times and not more than 0.5 times the groove width G2. If it is less than 0.25 times, the protruding amount of the soundproofing piece 6 is insufficient, so the sound insulating effect is small, and if it exceeds 0.5 times, the rainwater flow path is blocked by the soundproofing piece 6 and the wet braking performance is deteriorated.
The thickness T of the soundproof piece 6 is preferably 0.25 times or more the groove width GW. If it is less than 0.25 times, the soundproof piece 6
May have insufficient rigidity and may vibrate due to air passing through the vertical groove G, resulting in resonance noise.

The height H of the soundproof piece 6 in the groove depth direction is not less than 0.25 times and not more than 0.5 times each groove depth GH of the vertical groove G, and the lower surface 6A thereof has the vertical groove G. Above the groove bottom D and from the groove bottom D 0.25 times the groove depth GH or more and 0.5
It is preferable that the distance B is not more than double. When the distance B is less than 0.25 times the groove depth, when the tread surface 2 is worn and the groove depth becomes shallow, the drainage of the vertical groove is poor and the wet braking performance is deteriorated. If it exceeds 0.5 times, the sound insulation effect may decrease.

Such sound insulation pieces 6 are alternately arranged in the zigzag walls 4 and 5 of the vertical groove G in a zigzag manner, and the interval P between them is at least twice the thickness T of the sound insulation piece 6. preferable.

Further, the number of the soundproofing pieces 6 arranged is the ground area S.
In each of the vertical grooves G, 4 or more and 6 or less, that is, 2 or more and 3 or less are provided for the groove wall 4 on one side.

Note that the soundproof piece 6 has the above-mentioned distance P between the vertical grooves G.
1, G2, G3 may be the same, or each vertical groove G
The gap P may be different between 1, G2 and G3, and further,
Of the 5 or more vertical grooves G arranged in the ground area S, 4 to 6 are provided only in 3 vertical grooves, and the remaining vertical grooves may be increased or decreased with respect to the regulated number.

[0027]

[Examples] Tires having a tire size of 11R22.5 and having six vertical grooves in the ground contact area S, a plurality of types of tires in which the number N of soundproofing pieces 6 in the ground contact area S and the groove width ratio ΣGW / W are changed Was prototyped and its performance was tested.

Each of the test tires was mounted on a standard rim, an internal pressure of 8.0 kgf / cm ² was applied, the tires were mounted on all wheels of a 2D truck, and a normal load was applied to the tires. I went.

(A) Passing noise test This test was carried out by the actual vehicle coasting test method specified in JASO C606, and the above vehicle equipped with a test tire consisting of six vertical grooves was tested at a constant speed and at a speed of 50 m on a linear test course. While passing a distance, at a midpoint of the course, the passing noise was measured by a stationary microphone installed at a distance of 7.5 m laterally from the running center line and at a height of 1.2 m from the test road surface, and the passing noise was measured. The maximum sound level is shown in dB (A). The passing speed was set to 50 km / H during the test. The test results are shown graphically in FIG.

(B) Wet braking test The vehicle equipped with test tires was tested on a linear wet road for 50 minutes.
11R2, which is the same size as the test tire and is widely used as the standard, for the reciprocal of the distance until the vehicle stops by coasting at a speed of km / H and applying sudden braking.
2.5 The value is shown as an index with the measured value of 14 PSP160 tire (5 vertical grooves) being 100. The larger the value, the better. The test results are shown in the graph of FIG.

As a result of the above two tests, passing noise was 70 dB while maintaining wet braking performance equivalent to that of a conventional tire.
It was confirmed that it is necessary that the number of grooves is 5 or more and the groove width ratio ΣWG / SW is 0.16 or less in order to achieve (A) or less.

[0032]

As described above, in the tire of the present invention, five or more tires are provided in the ground contact area of the tread surface, and the groove width ratio between the sum of the groove widths and the ground contact width is restricted to the range of 0.12 to 0.16. On the other hand, since 4 to 6 soundproof pieces are provided in a zigzag pattern in at least 3 vertical grooves, the passing noise of the tire can be reduced while maintaining the wet braking performance.

[Brief description of drawings]

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

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

FIG. 3 is a plan view showing an enlarged vertical groove.

FIG. 4 is a sectional view taken along the line AA.

FIG. 5 is a graph showing a passing noise level in a relationship between the number of vertical grooves and a groove width ratio.

FIG. 6 is a graph showing the wet braking property in relation to the number of vertical grooves and the groove width ratio.

[Explanation of symbols]

 2 Tread surface 4, 5 Groove wall 6 Soundproof piece 6A Lower surface D Groove bottom G Vertical groove GW Groove width J Rim S Grounding area SW Grounding width

Claims (1)

[Claims] 1. A tire having a rib pattern in which a straight vertical groove extending in the tire circumferential direction is provided on a tread surface, the tire being mounted on a standard rim and grounded when a normal internal pressure and a normal load are applied. The vertical width of the groove width ratio ΣGW / SW is 0.12 or more and 0.16 or less, in which the total sum ΣGW of the groove widths GW and the ground width, which is the width of the ground area in the tire axial direction, is not less than 0.12. While providing the groove, at least 3
In the vertical groove of the book, a soundproof piece whose lower surface is located above the groove bottom of the vertical groove and which alternately protrudes in a zigzag pattern from both groove walls is formed on both groove walls sandwiching the vertical groove. In addition, the tire is characterized in that the number of soundproof pieces is 4 or more and 6 or less in each vertical groove in the ground contact area.