TREAD FOR A PNEUMATIC TIRE

Abstract

A tread for a tire includes a first circumferential groove extending in a circumferential direction of the pneumatic tire, a second circumferential groove extending in the circumferential direction of the pneumatic tire, a third circumferential groove extending in the circumferential direction of the pneumatic tire, and a fourth circumferential groove extending in the circumferential direction of the pneumatic tire. The first, second, third, and fourth circumferential grooves defining first, second, third, fourth, and fifth ribs. The first and fifth ribs include lateral grooves and incisions extending circumferentially fully around the first and fifth ribs. The incisions of the first and fifth ribs reduce noise generated by the tread under operating conditions.

Claims

1. A tread for a tire comprising: a first circumferential groove extending in a circumferential direction of the pneumatic tire; a second circumferential groove extending in the circumferential direction of the pneumatic tire; a third circumferential groove extending in the circumferential direction of the pneumatic tire; and a fourth circumferential groove extending in the circumferential direction of the pneumatic tire, the first, second, third, and fourth circumferential grooves defining first, second, third, fourth, and fifth ribs, the first and fifth ribs including lateral grooves; and incisions extending circumferentially fully around the first and fifth ribs, the incisions of the first and fifth ribs reducing noise generated by the tread under operating conditions.

2. The tread as set forth in claim 1 wherein the first rib has between 6 and 12 incisions.

3. The tread as set forth in claim 1 wherein the fifth rib has between 6 and 12 incisions.

4. The tread as set forth in claim 1 wherein the incisions of the first rib have a depth between 1.0 mm and 4.0 mm.

5. The tread as set forth in claim 1 wherein the incisions of the fifth rib have a depth between 1.0 mm and 4.0 mm.

6. The tread as set forth in claim 1 wherein the incisions of the first rib have a lateral spacing between 1.0 mm and 6.0 mm.

7. The tread as set forth in claim 1 wherein the incisions of the fifth rib have a lateral spacing between 1.0 mm and 6.0 mm.

8. The tread as set forth in claim 1 wherein the incisions of the first rib have a width between 0.5 mm to 1.5 mm.

9. The tread as set forth in claim 1 wherein the incisions of the fifth rib have a width between 0.5 mm to 1.5 mm.

10. The tread as set forth in claim 1 wherein the incisions of the first and fifth ribs have depths of 2.0 mm.

11. A pneumatic tire with a tread comprising: a first circumferential groove extending in a circumferential direction of the pneumatic tire; a second circumferential groove extending in the circumferential direction of the pneumatic tire; a third circumferential groove extending in the circumferential direction of the pneumatic tire; and a fourth circumferential groove extending in the circumferential direction of the pneumatic tire, the first, second, third, and fourth circumferential grooves defining first, second, third, fourth, and fifth ribs, each of the first, second, third, fourth, and fifth ribs including incisions extending circumferentially fully around the tread, the incisions reducing noise generated by the tread under operating conditions.

12. The pneumatic tire as set forth in claim 11 wherein each rib has between 6 and 12 incisions.

13. The pneumatic tire as set forth in claim 11 wherein the incisions of each rib have a depth between 1.0 mm and 4.0 mm.

14. The pneumatic tire as set forth in claim 1 wherein the incisions of each rib have a lateral spacing between 1.0 mm and 6.0 mm.

15. The pneumatic tire as set forth in claim 1 wherein the incisions of each rib have a width between 0.5 mm to 1.5 mm.

16. A method for reducing noise created by a tread of a pneumatic tire under operating conditions, the method comprising the steps of: extending a first incision across the tread in a circumferential direction; and extending a second incision across the tread in the circumferential direction, the second incision being parallel to the first incision and an axial distance from the first incision between 1.0 mm and 5.0 mm, edge to edge.

17. The method as set forth in claim 16 wherein the first and second incisions each have a radial depth between 1.0 mm and 4.0 mm.

18. The method as set forth in claim 17 wherein the first and second incisions each have an axial width between 0.5 mm and 1.5 mm.

19. The method as set forth in claim 18 wherein the first and second incisions each have a radial depth of about 2.0 mm.

20. The method as set forth in claim 19 further including the step of extending third, fourth, fifth, and sixth incisions across the tread in the circumferential direction, the third, fourth, fifth, and sixth incisions being parallel to the first and second incisions and an axial distance from an adjacent incision between 1.0 mm and 5.0 mm, circumferential edge to circumferential edge.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The present invention will be more clearly understood by the following description of some examples thereof, with reference to the accompanying drawings, in which:

[0051] FIG. 1 is a schematic orthogonal front view of a pneumatic tire having a tread in accordance with the present invention.

[0052] FIG. 2 is a schematic orthogonal detail view of the pneumatic tire and tread of FIG. 1.

[0053] FIG. 3 is a schematic sectional view of the pneumatic tire and tread pattern along line 3-3 in FIG. 2.

[0054] FIG. 4 is a graph of ambient tire noise versus excitation frequency for three different treads.

DESCRIPTION OF EXAMPLES OF THE PRESENT INVENTION

[0055] As shown in FIGS. 1-3, a pneumatic tire 1 in accordance with the present invention may include a tread 100 with a first main circumferential groove 10, a second main circumferential groove 20, a third main circumferential groove 30, and a fourth main circumferential groove 40 all extending in a circumferential direction C of the pneumatic tire forming the tread 100. Five land portions, or ribs 110, 120, 130, 140, 150 may be formed by these main circumferential grooves 10, 20, 30, 40. Each of the first and fifth ribs 110, 150 may have additional lateral grooves 112, 152 extending laterally L across the ribs 110, 150 forming discreet and circumferentially repeating blocks, or tread elements. The main circumferential grooves 10, 20, 30, 40 may have, for example, a lateral width between 3.0 mm and 20.0 mm and an example radial depth between 5.0 mm and 13.0 mm.

[0056] In accordance with the present invention, the first shoulder rib 110 may further have a plurality of circumferential incisions 111, or zebra stripes, extending fully around the circumference of the first rib. These incisions 111 may continue circumferentially through each of the lateral grooves 112. The number of incisions 111 may range from 2 to 12. The incisions 111 may have depths ranging from 1.0 mm to 4.0 mm, or about 2.0 mm. The incisions 111 may have widths ranging from 0.5 mm to 1.5 mm. The incisions 111 may have a lateral spacing, incision edge to incision edge, ranging from 1.0 mm to 5.0 mm. Said another way, the incisions 111 may be separated by ribs between 1.0 mm and 4.0 mm. The depth, width, and lateral spacing of the incisions 111 may all effect the amount of ambient noise mitigation produced by the incisions. Generally, mm may be an optimal depth and a greater density of incisions 111 decreases noise more than a lesser density of incisions.

[0057] In accordance with the present invention, the second intermediate rib 120 may further have a plurality of circumferential incisions 211, or zebra stripes, extending fully around the circumference of the second rib. The number of incisions 211 may range from 2 to 12. The incisions 211 may have depths ranging from 1.0 mm to 4.0 mm, or about 2.0 mm. The incisions 211 may have widths ranging from 0.5 mm to 1.5 mm. The incisions 211 may have a lateral spacing, incision edge to incision edge, ranging from 1.0 mm to 6.0 mm. Said another way, the incisions 211 may be separated by ribs between 1.0 mm and 5.0 mm. The depth, width, and lateral spacing of the incisions 211 may all effect the amount of ambient noise mitigation produced by the incisions. Generally, 2.0 mm may be an optimal depth and a greater density of incisions 211 decreases noise more than a lesser density of incisions.

[0058] In accordance with the present invention, the third center rib 130 may further have a plurality of circumferential incisions 311, or zebra stripes, extending fully around the circumference of the third rib. The number of incisions 311 may range from 2 to 12. The incisions 311 may have depths ranging from 1.0 mm to 4.0 mm, or about 2.0 mm. The incisions 311 may have widths ranging from 0.5 mm to 1.5 mm. The incisions 311 may have a lateral spacing, incision edge to incision edge, ranging from 1.0 mm to 6.0 mm. Said another way, the incisions 311 may be separated by ribs between 1.0 mm and 5.0 mm. The depth, width, and lateral spacing of the incisions 311 may all effect the amount of ambient noise mitigation produced by the incisions. Generally, 2.0 mm may be an optimal depth and a greater density of incisions 311 decreases noise more than a lesser density of incisions.

[0059] In accordance with the present invention, the fourth intermediate rib 140 may further have a plurality of circumferential incisions 411, or zebra stripes, extending fully around the circumference of the fourth rib. The number of incisions 411 may range from 2 to 12. The incisions 411 may have depths ranging from 1.0 mm to 4.0 mm, or about 2.0 mm. The incisions 411 may have widths ranging from 0.5 mm to 1.5 mm. The incisions 411 may have a lateral spacing, incision edge to incision edge, ranging from 1.0 mm to 6.0 mm. Said another way, the incisions 411 may be separated by ribs between 1.0 mm and 5.0 mm. The depth, width, and lateral spacing of the incisions 411 may all effect the amount of ambient noise mitigation produced by the incisions. Generally, 2.0 mm may be an optimal depth and a greater density of incisions 411 decreases noise more than a lesser density of incisions.

[0060] In accordance with the present invention, the fifth shoulder rib 150 may further have a plurality of circumferential incisions 511, or zebra stripes, extending fully around the circumference of the fifth rib. These incisions 511 may continue circumferentially through each of the lateral grooves 152. The number of incisions 511 may range from 2 to 12. The incisions 511 may have depths ranging from 1.0 mm to 4.0 mm, or about 2.0 mm. The incisions 511 may have widths ranging from 0.5 mm to 1.5 mm. The incisions 511 may have a lateral spacing, incision edge to incision edge, ranging from 1.0 mm to 6.0 mm. Said another way, the incisions 511 may be separated by ribs between 1.0 mm and 5.0 mm. The depth, width, and lateral spacing of the incisions 511 may all effect the amount of ambient noise mitigation produced by the incisions. Generally, 2.0 mm may be an optimal depth and a greater density of incisions 511 decreases noise more than a lesser density of incisions.

[0061] As can be seen in FIG. 4, a tread pattern 401 with no incisions produces more noise than the same tread pattern 402 having incisions 111, 511 only in the shoulder ribs 110, 150, as described above. Further, the tread pattern 402 with incisions 111, 511 only in the shoulder ribs 11, 150 produces more noise than the same tread pattern 403 having incisions 111, 211, 311, 411, 511 in all five ribs 110, 120, 130, 140, 150, as described above. These incisions 111, 211, 311, 411, 511 in each rib 110, 120, 130, 140, 150 (FIGS. 1-3) may reduce noise by as much as 1.4 dBA to 2.4 dBA at a tire speed of 50 kph. The incisions 111, 211, 311, 411, 511 have been shown to have little or no effect on rolling resistance of the tire 1 (e.g., +/2 percent, etc.).

[0062] While the present invention has been described in connection with what is considered the most practical example, it is to be understood that the present invention is not to be limited to the disclosed arrangements, but is intended to cover various arrangements which are included within the spirit and scope of the broadest possible interpretation of the appended claims so as to encompass all possible modifications and equivalent arrangements.