Tire with apertured shoulder block for improved temperature control

A tire is provided having a plurality of shoulder blocks separated by axial grooves and located along at least one side of the tire. Apertures extend through the shoulder blocks to connect with a circumferential groove. The apertures are located within a certain radial position relative to the axial grooves. Each aperture has a bottom positioned at a radial depth HB relative to the shoulder block and extends completely through the shoulder block along the axial direction. Each aperture has a radial overlap HL with the axial grooves. The ratio HL/Ho is about 0.15 or less and the ratio of HB/H is in the range of about 1.0 to about 1.1.

FIELD OF THE INVENTION

The present invention relates to a tire having a plurality of shoulder blocks separated by axial grooves and located along at least one side of the tire. Apertures extend through the shoulder blocks to connect with a circumferential groove. The apertures are located within a certain radial position relative to the axial grooves.

BACKGROUND OF THE INVENTION

Tires having holes, channels, or incisions extending from a lateral surface of the tire have been previously indicated. Such features can confer advantageous properties to a tire having tread of sufficient thickness. For example, channels can be provided that will emerge at the surface of the tread as wear proceeds so as to assist with traction on wet surfaces without sacrificing desirable properties of the tread when new. Channels can also provide ventilation and therefore a cooling effect for the tire.

By way of example, U.S. 2006/0090827 provides a tread having channels located along an offset rib. EP 0 625 436 shows an angled channel extending into part of the tread. U.S. Pat. No. 2,121,955 indicates incisions in a tire tread that are transverse to the rib. WO 00/00357 indicates channels extending under the tread features for removing medium away from the contact surface of the tire. U.S. 2005/0253304 indicates a process for placing a channel into the tire extending from the tire's lateral surface.

As set forth below, applicant has discovered an advantageous tire construction where apertures extend completely through a plurality of shoulder blocks and are positioned as herein described.

SUMMARY OF THE INVENTION

A summary of exemplary embodiments of the present invention will be set forth here. Using the description provided herein, one skilled in the art will understand that additional exemplary embodiments are within the scope of the present invention.

In one exemplary embodiment of the invention, a tire is provided having a circumferential groove of radial depth Ho, and a plurality of axial grooves of radial depth H and circumferential width W. A plurality of shoulder blocks are located circumferentially about at least one shoulder of the tire and have a height equal to radial depth Ho. The shoulder blocks are defined by the circumferential groove and the axial grooves. The axial grooves separate adjacent shoulder blocks. Each shoulder block has a circumferential length B. A plurality of apertures are positioned in the plurality of shoulder blocks.

At least one aperture is located within each shoulder block. Each aperture has a bottom positioned at a radial depth HBrelative to the shoulder block and extends completely through the shoulder block along the axial direction. Each aperture has a radial overlap HLwith the axial grooves. The ratio HL/Hois about 0.15 or less and the ratio of HB/H is in the range of about 1.0 to about 1.1.

Additional features may be provided to this exemplary embodiment to create yet additional embodiments of the present invention. For example, for circumferential widths W of about 1 mm or more, the ratio of H/Homay be in the range of about 0.5 to about 0.9 or, even more particularly, the ratio of H/Homay be in the range of about 0.7 to about 0.9.

Each aperture defines a cross-sectional area AL, and each said shoulder block defines a cross-sectional area of B*Ho. In certain embodiments, the ratio of AL/(B*Ho) is in the range of about 0.007 to about 0.05 or, even more particularly, the ratio of AL/(B*Ho) is in the range of about 0.01 to about 0.03.

In certain embodiments, the ratio of B/Hois in the range of about 1 to about 4 or, even more particularly, in the range of about 2 to about 3. The ratio HL/Homay be about 0.1 or less. The ratio of HB/Homay be about 1.0.

Each shoulder block has a least one aperture and may have several apertures. In certain embodiments, a tire according to the present invention has only two apertures along the shoulder block. The apertures may be substantially circular in cross-section but other shapes may also be employed. A plurality of lamellae may be provided for connecting the plurality of apertures with the outer radial surface of the tire.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As used herein, the following terms have these definitions:

The term “radial” refers to the direction perpendicular to the axis of rotation of the tire as is designated with arrow R inFIGS. 1 and 2.

The term “axial” refers to the directions parallel to the axis of rotation of the tire and is designated with arrows A inFIG. 1.

The term “circumferential” refers to the circular direction defined by a radius of fixed length as it is rotated about the axis of rotation of the tire and is designated with arrows CFIGS. 1 and 2.

The term “lateral surfaces” refers to the outside surfaces along the sides of the tire.

A partial perspective view of an exemplary embodiment of a tire10according to the present invention is shown inFIG. 1. A schematic, side view of tire10is shown inFIG. 2. As depicted, tire10includes a plurality of shoulder blocks20separated by axial grooves30, i.e., grooves oriented along the axial directions A. Each groove30has a width W along the circumferential direction C and depth H along radial direction R. Preferably, width W should be at least about 1 mm. Each shoulder block20has a length B along the circumferential direction C, which also represents the distance between grooves30. Each shoulder block20is spaced circumferentially about the shoulder of tire10and is located adjacent to circumferential groove60, which extends about the circumference of the tire separating shoulder blocks20from other tread features of the tire. As shown inFIG. 2, the depth of circumferential groove60is equal to radial depth Hoand, with axial grooves30, provides a shoulder block20having a height equal to radial depth Ho. Stated alternatively, each shoulder block20has a height relative to circumferential groove60that is equal to radial depth Ho. In general, the lengths B of blocks20ranges between about 1 to about 4 times radial depth Ho.

Each shoulder block20includes an aperture40that extends completely through block20along axial directions A.FIGS. 1 and 2each depict a single aperture of circular cross-section that is positioned along the middle of each shoulder block20. However, the present invention includes other configurations as provided in the claims that follow. By way of example, aperture40may have a non-circular cross-section and may be located at different locations along block20. Additionally, more than one aperture40may be positioned within a block20. For example, in one exemplary embodiment, block20includes two apertures with each having a circular cross-section. Blocks20having apertures40may be located on one or both sides of tire10.

In general, the shoulder region of a tire can be provided with apertures that may facilitate traction and cooling as the tire is worn through operation. Improved cooling of the tire architecture may result as the apertures are moved relative to the tire's belts and/or carcass. More specifically, improvements in operating temperatures can result by moving apertures away from outer radial surface50and towards the center of the tire to increase the rate of heat transfer with air flowing through the apertures. However, as now set forth, applicant has determined that improvements in tire temperature and wear can be obtained by constructing a tire having apertures40within a specific location and configuration determined with regard to grooves30instead of the tire's belts and or carcass.

Referring toFIG. 2, each aperture40has a bottom70defined as the most radially-inward extent of aperture40. Relative to outer radial surface50, aperture bottom70is located at a radial depth HB. Along radial direction R, grooves30should have a radial overlap HLwith aperture40. Furthermore, applicant has discovered improvements in temperature and endurance when the amount of radial overlap HLdoes not exceed about 15 percent of Ho. Additionally, radial depth HBshould not exceed the depth H of groove30by more than about ten percent. Stated alternatively, the ratio HL/Hoshould be about 0.15 or less, and the ratio HB/H should be in the range of about 1 to about 1.1. In still other exemplary embodiments of the present invention, the ratio of HL/Hoshould be about 0.10 or less. Further, in still other exemplary embodiments, the ratio of HB/H should be about 1.

As stated, aperture40extends completely through block20to provide a path for air flow between the exterior of tire10and circumferential groove60. Aperture40is otherwise not in direct communication with the exterior of tire10. In certain embodiments, aperture40may be connected to the outer radial surface50of tire10by a lamella such as, for example, a lamella with a wavy or curved-shape along both axial direction A and radial direction R.