Incised tread for civil engineering tire

Patent metadata

Field	Value
Publication number	US-10780745-B2
Application number	US-201515320949-A
Country	US
Kind code	B2
Filing date	Jun 16, 2015
Priority date	Jun 24, 2014
Publication date	Sep 22, 2020
Grant date	Sep 22, 2020

Abstract

The tread has a total width W and is provided with circumferential cuts that have a mean depth at least equal to 70 mm and at most equal to the thickness of wearable material. The circumferential cuts divide the tread into a middle region with an axial width Wm of 50% to 80% of the total width W. The middle region has transverse or oblique sipes opening into the circumferential cuts and closing at least in part when they enter the contact patch. The sipes have a depth at least equal to 75% of the depth of the circumferential cuts and delimit elements of material of height equal to the mean depth H of the said sipes and of circumferential length B equal to the mean distance between two sipes. For all the elements of material, the ratio H/B is greater than 0.5 and at most equal to 2.5.

First claim

The invention claimed is:

1. A tread for a tire of a vehicle carrying very heavy loads, this tread having a total width W and a thickness of wearable material, this tread being provided with at least two cuts of circumferential overall orientation and of mean depth at least equal to 70 mm and at most equal to the thickness of wearable material, these circumferential cuts dividing the tread into a middle region, and shoulder regions axially delimiting the tread, the middle region being defined as the region of the tread situated between the two circumferential cuts axially furthest away from the equatorial median plane, this middle region having an axial width Wm at least equal to 50% and at most equal to 80% of the total width W of the tread, this tread being such that the middle region comprises a plurality of transverse or oblique sipes opening into the circumferential cuts, these transverse or oblique sipes closing at least in part when they enter the contact patch and having a depth at least equal to 75% of the depth of the circumferential cuts, these transverse or oblique sipes delimiting a plurality of elements of material of height equal to the mean depth H of the said sipes and of circumferential length B equal to the mean distance between two transverse or oblique sipes wherein, for all the elements of material which are delimited by two consecutive sipes in the middle region, the ratio H/B is greater than 0.5 and at most equal to 2.5;
wherein the circumferential cuts extend in a straight direction around an entire circumference of the tread;
wherein the sipes extend in a straight direction fully across the elements of material; and
wherein the plurality of elements of material includes three circumferential rows of elements of material delimited by circumferential cuts, wherein the axially innermost circumferential cuts are offset from the equatorial median plane such that a middle circumferential row of elements of material is defined, and wherein the sipes of the elements of material of the middle circumferential row extend through the equatorial median plane.

2. The tread according to claim 1 , wherein the ratio H/B is at least equal to 1.0 and at most equal to 2.0.

3. The tread according to claim 1 , wherein the void volume ratio Tc of the middle region is at least equal to 2% and at most equal to 12%.

4. The tread according to claim 3 , wherein the void volume ratio Tc of the middle region is at least equal to 2% and at most equal to 10%.

5. The tread according to claim 1 , wherein the angle of the transverse or oblique sipes is at least equal to 45° to the circumferential direction.

6. The tread according to claim 1 , wherein at least some of the transverse or oblique sipes comprise means for blocking relative movements of the opposing walls that delimit these sipes.

7. The tread according to claim 1 , wherein at least one shoulder region—a region axially limiting the tread—is provided with a plurality of transverse or oblique sipes opening on one side into a circumferential cut delimiting this shoulder region and on the other side onto an axial outside of the tread, these transverse or oblique sipes closing at least in part when they enter the contact patch and having a depth at least equal to 75% of the depth of the circumferential cuts, and these transverse or oblique sipes delimiting a plurality of elements of material of height equal to the mean depth H* of the transverse or oblique sipes of the shoulder region and of circumferential length B* equal to the mean distance between two transverse or oblique sipes, this shoulder region being such that the ratio H*/B* is greater than 0.5 and at most equal to 2.5.

8. The tread according to claim 7 , wherein the shoulder region is such that the ratio H*/B* is at least equal to 1 and at most equal to 2.

9. The tread according to claim 1 , wherein the sipes include, in the circumferential direction, an alternation of sipes provided with blocking means and of sipes not provided with such blocking means, the blocking means being configured to limit the relative movement of the opposing walls that define the respective sipes with blocking means, two sipes not provided with blocking means flanking one sipe or several sipes that are provided with blocking means.

10. The tread according to claim 9 , wherein the distance B′ between two sipes that are not provided with blocking means is such that the ratio H/B′ is less than 1.

11. The tread according to claim 10 , wherein the distance B′ between two sipes that are not provided with blocking means is such that the ratio H/B′ is less than 0.7.

12. The tread according to any claim 1 , wherein the void volume ratio of the tread as a whole is comprised between 2 and 12% and in that the void volume ratio of the middle region of the tread is at least equal to 2% and at most equal to 14%, and more preferably comprised between 2% and 10%.

13. A tire comprising a tread constructed according to claim 1 , wherein the width Wm of the middle region is equal to at least 70% and at most 80% of the total width W of the tread.

14. The tread according to claim 1 , wherein adjacent circumferential rows are offset circumferentially such that the sipes opening into the circumferential cuts terminate at the circumferential cuts, each of the sipes being offset from the sipes in adjacent circumferential rows.

Assignees

• Michelin & Cie
• Michelin Rech Tech

Inventors

• Barbarin Francois
• Demaziere Guillaume

Classifications

• B60C11/0306

  Patterns comprising block rows or discontinuous ribs · CPC title

• B60C2200/065

  for construction vehicles · CPC title

• B60C2011/0355

  characterised by depth · CPC title

• B60C11/0311

  Patterns comprising tread lugs arranged parallel or oblique to the axis of rotation · CPC title

• B60C2011/1209

  straight at the tread surface · CPC title