JP3103641B2 - tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention regulates the number of vertical grooves extending in the circumferential direction of the tread surface and the total sum of the groove widths, and provides soundproofing pieces in the vertical grooves without reducing wet braking performance. The present invention relates to a tire capable of reducing passing noise.

[0002]

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

[0003] On the other hand, the formation of the longitudinal grooves causes air compressed by the compressed air between the tread surface and the road surface to suddenly discharge through the longitudinal grooves in the form of a column. The noise passing through the tire is increased by the air pumping noise. As the performance and sophistication of vehicles have increased, tires have become more strictly required not only to improve wet braking performance but also to reduce tire noise.

[0004]

In order to reduce the passing noise, the longitudinal grooves have been straightened, the number of grooves has been reduced, and the volume of the grooves has been reduced. The resulting tires are inferior in other running performances, especially in wet braking performance, and the appearance of the tires at the end of wear is inferior. As described above, promotion of noise reduction and improvement of wet braking performance have a trade-off relationship.

[0005] The inventors of the present invention have conducted intensive studies to improve the balance between the reduction of passing noise and the wet braking performance, and as a result, have increased the number of flutes arranged in the ground contact area as compared with ordinary tires. To reduce the groove width per vertical groove and to regulate the total width of the groove. To prevent sudden outflow of air from the vertical groove, which causes air column noise on the groove wall surface The present inventors have found that by providing soundproofing pieces in the vertical grooves, it is possible to reduce the passing noise of the tire without lowering the wet braking performance, and completed the present invention.

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

[0007]

SUMMARY OF THE INVENTION The present invention relates to a tire having a rib pattern in which a straight groove extending in the circumferential direction of the tire is provided on a tread surface. The tire is mounted on a standard rim and has a normal internal pressure and a normal load. In the normal contact region where the contact is made, the groove width ratio 少 な く と も GW / SW of at least five and the sum of the groove widths GW and the contact width, which is the width of the contact region in the tire axial direction, is at least 0.12. And a vertical groove of 0.16 or less is provided, and at least three vertical grooves are located on both groove walls sandwiching the vertical groove, and the lower surface is located above the groove bottom of the vertical groove and is provided in the vertical groove. The tire is characterized in that soundproofing pieces projecting alternately from both groove walls in a staggered manner are formed, and the number of soundproofing pieces is set to 4 or more and 6 or less in each vertical groove in the ground area.

[0008]

[Function] Since five or more flutes extend in a straight line and are arranged in the ground area at least five times, rainwater adhering to the ribs between the flutes can be effectively guided to the flutes and the rainwater in the flutes can be efficiently discharged. Thereby, the wet braking force can be maintained.

The groove width ratio ΔGW / SW is set to 0.12 or more and 0.16 or less. By making the total sum を GW of the groove widths GW smaller than that of a normal one, the total cross-sectional area of the air column formed by the vertical groove and the ground during traveling can be reduced, and mainly the air pumping noise is generated. Passing noise can be reduced. When the groove width ratio ΣGW / SW is less than 0.12, the drainage is inferior and the wet braking performance is reduced.
If the ratio exceeds 0.16, reduction of passing noise cannot be achieved.

[0010] At least three of the vertical grooves located in the grounding area are provided with soundproof pieces that alternately project in a staggered manner on both groove walls sandwiching the vertical grooves. By providing such a soundproofing piece, while reducing the outflow speed of air from the vertical groove when the tire is in contact with the ground, by providing the soundproofing pieces in a staggered manner, the flow of air is made wavy, and the outflow speed is reduced. Thus, air pumping noise can be reduced.

If the number of soundproofing pieces provided in each vertical groove in the ground contact area is less than four, the effect of suppressing noise is small. Even if a large number of soundproofing pieces are provided in excess of six, the noise hardly changes. Conversely, the drainage from the vertical groove becomes defective, and the wet braking performance is reduced.

In addition, the lower surface of the soundproofing piece is positioned above the width of the vertical groove. This prevents cracks from occurring at the groove bottom where cracks are most likely to occur in the tread, and ensures drainage even when the groove depth becomes shallow due to wear of the tread surface. This is to maintain wet braking performance.

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

[0014]

An embodiment of the present invention will be described below with reference to the drawings. 1 to 4, the 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 linear groove extending in a straight line. .

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

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

In the present embodiment, the belt layer 17 is composed of four belt plies. Each belt ply is made of an organic fiber such as nylon, polyester, aromatic polyamide or a steel cord or a belt cord inclined with respect to the tire equator C. It is juxtaposed.

On the tread surface 2, a ground contact area S where the tire 1 is mounted on a standard rim J and a normal internal pressure and a normal load are applied is virtually set. Central longitudinal groove G arranged on the tire equator C
1, 1 arranged on both sides in the tire axial direction of the central longitudinal groove G1
Five longitudinal grooves G including a pair of intermediate longitudinal grooves G2, G2, and a pair of outer longitudinal grooves G3, G3 arranged outside the intermediate longitudinal grooves G2 in the tire axial direction are arranged.

The widths WG of the central longitudinal groove G1, the intermediate longitudinal groove G2, and the outer longitudinal grooves in the tire axial direction are slightly different in the present embodiment. Groove width WG of central vertical groove G1
1. Groove width WG2 of middle longitudinal groove, groove width WG of outer longitudinal groove G3
3, the groove width ratio ΣGW / SW, which is the ratio of the sum 溝 GW of the groove widths GW, which is the sum of the gross width 3 and ３GW = WG1 + 2 × WG2 + 2 × WG3, to the contact width SW forming the width in the tire axial direction in the contact area S. It is 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 as the same groove width. The depth GH of each of the vertical grooves G1, G2, G3 is determined by the grounding width S.
It is preferable to set the range of 0.05 to 0.16 times W.

The central vertical groove G1, the intermediate vertical grooves G2, G
2 and the outer vertical grooves G3, G3, as shown in FIGS. 3 and 4, two groove walls 4, 5 sandwiching these vertical grooves G1, G2, G3. A soundproofing piece 6 protrudes in a direction substantially perpendicular to 5.

It is preferable that the projecting length L of the soundproofing piece 6 from the opening edge F to the tip end of the mounting groove wall 4 is 0.25 times or more and 0.5 times or less the groove width G2. If it is less than 0.25 times, the protrusion of the soundproofing piece 6 is insufficient, so that the sound insulation effect is small. If it exceeds 0.5 times, the flow path of rainwater is blocked by the soundproofing piece 6, and the wet braking performance is reduced.
The thickness T of the soundproofing 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 the air passing through the vertical groove G to generate a resonance sound.

The height H of the soundproofing piece 6 in the groove depth direction is not less than 0.25 times and not more than 0.5 times each of the groove depths GH of the vertical groove G. 0.25 times or more and 0.5 or more of the groove depth GH above the groove bottom D and from the groove bottom D
It is preferable to arrange them at a distance B that is twice or less. When the distance B is less than 0.25 times the groove depth, when the groove depth becomes shallow due to abrasion of the tread surface 2, the drainage of the vertical groove is inferior and the wet braking performance is reduced. If it exceeds 0.5 times, the sound insulation effect may be reduced.

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

The number of the soundproofing pieces 6 is determined by the number of the grounding areas S.
Four or more and six in each vertical groove G, that is, two or more and three or less are provided for the groove wall 4 on one side.

Note that the soundproofing piece 6 is provided with the above-mentioned space P in each vertical groove G.
1, G2 and G3 may be the same or each vertical groove G
1, the gap P may be different between G2 and G3.
Of the five or more vertical grooves G arranged in the ground area S, 4 to 6 are provided only in three vertical grooves, and the remaining vertical grooves may be increased or decreased with respect to the regulated number.

[0027]

[Specific example] A plurality of types of tires having a tire size of 11R22.5 and having six longitudinal grooves in the contact area S, in which the number N of soundproofing pieces 6 in the contact area S and the groove width ratio ΣGW / W are changed. And a test of its performance.

Each test tire 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 test was performed with a regular load applied to the tires. Was done.

A) Passing noise test The vehicle was tested according to the actual vehicle coasting test method specified in JASO C606. The vehicle equipped with the test tires having six longitudinal grooves was mounted on a linear test course at a constant speed and a speed of 50 m. The coasting distance was measured, and the passing noise was measured by a fixed microphone installed at a height of 1.2 m from the test road surface at a distance of 7.5 m laterally from the center line of travel at the midpoint of the course. The maximum sound level is shown in dB (A). During the test, the passing speed was set to 50 km / H. The test results are shown graphically in FIG.

B) Wet braking test The vehicle equipped with the test tires was placed on a straight wet road for 50 minutes.
The reciprocal of the distance until the vehicle is stopped by coasting at a speed of km / H and suddenly applying a brake to the vehicle is the same as that of the test tire and widely used as a standard 11R2.
2.5 The index was defined as an index with the measured value of 14 PSP160 in a tire (5 longitudinal grooves) being 100. The higher the value, the better. The test results are shown in the graph of FIG.

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

[0032]

As described above, in the tire of the present invention, the groove width ratio of the sum of the groove widths to the contact width is regulated to be in the range of 0.12 to 0.16 in the tire in the contact area on the tread surface. On the other hand, since four to six soundproof pieces are provided in at least three longitudinal grooves in a staggered manner, it is possible to reduce the passing noise of the tire while maintaining wet braking performance.

[Brief description of the drawings]

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

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

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

FIG. 4 is a sectional view taken along 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 wet braking performance in a relationship between the number of longitudinal grooves and a groove width ratio.

[Explanation of symbols]

 2 Tread surface 4, 5 Groove wall 6 Soundproofing piece 6A Bottom surface D Groove bottom G Vertical groove GW Groove width J Rim S Ground area SW Ground width

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60C 11/04 B60C 11/13

Claims (1)

(57) [Claims] 1. A tire having a rib pattern having a straight longitudinal groove extending in a tire circumferential direction on a tread surface, the tire being mounted on a standard rim and being grounded when a normal internal pressure and a normal load are applied. In the contact area, the groove width ratio ΣGW / SW between the sum of the at least five grooves GW and the contact width, which is the width of the contact area in the tire axial direction, is 0.12.
At least three vertical grooves are provided on both groove walls sandwiching the vertical groove, and the lower surface is located above the groove bottom of the vertical groove, and the vertical groove is formed in the vertical groove. In addition to the above, soundproofing pieces projecting alternately from both groove walls in a staggered manner are formed, and the number of soundproofing pieces is set to 4 or more and 6
The length L of the soundproofing piece projecting from the groove wall is determined by the groove width GW of the vertical groove.
0.25 times or more and 0.5 times or less, and the circumferential pitch P of the soundproofing piece is at least one
A tire characterized by being substantially the same in a vertical groove .