Patent Application
20190009617
The subject matter of the present disclosure relates generally to microsipes along lateral edges a tire's tread features such as e.g., the leading edge and trailing edge.
The design and manufacture of a tire typically requires consideration of numerous criteria including aesthetics, acoustics, energy efficiency, fraction, and braking performance under various anticipated road conditions and other concerns as well. Unfortunately, under conventional designs, the improvement of one performance criterion occurs at the expense of another. As such, tire designers may be forced to choose a compromise between these competing considerations.
One such example is the conventional compromise between traction and rolling resistance. Increased rolling resistance is undesirable because of its deleterious effect on a vehicle's fuel economy. In general, an improvement in traction will usually cause an increase in rolling resistance or an improvement in rolling resistance will usually result in a decrease in traction such as dry braking traction. If, for example, the composition of the rubber formulation is modified to improve braking performance, the rolling resistance is undesirably increased. Reducing tread depth can offer benefits for both dry braking and rolling resistance but typically comes at the expense of a decrease in wet or snow traction.
Tire design may also include the addition of tread features to control wear problems. For example, sipes have been applied to the sides of tire ribs in an effort to improve irregular wear problems particularly for tires used on commercial vehicles. However, depending upon e.g., the size and density, the addition of such sipes comes with an increase in rolling resistance and/or a decrease in handling performance.
Accordingly, tread features that can be used to improve the performance of a tire would be useful. More particular, tread features that can be added to a tire to improve its traction braking performance without increasing rolling resistance would be particularly beneficial.
The present invention provides a tire tread having microsipes along lateral edges such as the leading edge, trailing edge, or both of various tread features. The microsipes are oriented substantially along the longitudinal direction. In contravention of conventional teachings, the addition of these microsipes has been found to improve rolling resistance, dry braking, or both. The microsipes can be located along edges that are chamfered as well. Additional objects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.
In one exemplary embodiment, the present invention provides a tire defining longitudinal, radial, and axial directions. The tire includes a pair of opposing shoulders spaced apart along the axial direction with a tread portion extending between the shoulders. The tread portion includes a plurality of tread features, wherein each tread feature includes at least one leading edge extending along the axial direction and one trailing edge extending along the axial direction. A plurality of microsipes are positioned along the leading edge, the trailing edge, or both. The microsipes extends along the longitudinal direction and are positioned adjacent to each other.
In another exemplary embodiment, the present invention provides a tire that includes a tread portion extending along an axial direction of the tire between opposing shoulder portions. A plurality of tread blocks are positioned adjacent to each other along a longitudinal direction of the tire. The tread blocks are separated from each other by grooves, each tread block having a leading edge and a trailing edge adjacent to the grooves and extending along the axial direction. A plurality of microsipes are positioned along the leading edge, trailing edge, or both of the tread blocks. The microsipes extending longitudinally and arranged in a parallel and adjacent configuration.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
For purposes of describing the invention, reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
For this exemplary embodiment, tread portion 102 includes several rows 108, 110, 112, and 114 of tread features separated by grooves 116, 118, and 120 that each extend along longitudinal direction L. Exterior rows 108 and 114 include a plurality of tread blocks 122 and 124 separated by lateral grooves 138 and 144, respectively. Interior rows 112 and 144 include a plurality of tread blocks 126 and 128 separated by lateral grooves 140 and 142, respectively. Each tread block 122, 124, 126, and 128 includes a leading edge LE and a trailing edge TE. Sipes 150, 152, 154, and 160 of different shapes and lengths are also defined by tread blocks 122, 124, 126, and 128, respectively. Although each tread block is show with a pair of sipes extending along the axial direction, a different number and configuration may be used as well in other embodiments of the invention.
Continuing with
As shown in
Referring to
In certain exemplary embodiments of a tread portion 102 of the present invention, the leading edge LE of a tread feature such as tread blocks 122, 124, 126, and 128 may be substantially linear in shape as shown. Such leading edge LE can form a predetermined angle β with the longitudinal direction L as shown in
Still referring to
For the exemplary embodiment of
For the exemplary embodiments just described, the microsipes were located on the leading edge LE and trailing edge TE of a tread block. Using the teachings disclosed here, however, one of skill in the art will understand that microsipes could be located along other lateral edges of a tread feature such as e.g., edges on either side of a lateral groove in a tread block or a rib. As used herein, “lateral edge” means an edge that forms an angle θ of 45 degrees of less from axial direction A as shown in
As will be further described,
As now discussed, the results of the testing are surprising and contradict conventional teachings regarding the anticipated impact on rolling resistance and fraction during dry braking (descriptions of the test methods used are provided below). For example,
For a second round of rolling resistance testing, three different tires with three different treads were used. As shown in
Test Method Description—Dry Braking Test Method
The purpose of this test was to evaluate the braking performance of the tires on a vehicle. The test consists of a statistical analysis of stopping distances plus comments by the driver. One dry track is used for this test. Measurement of stopping distance is made with a calibrated accelerometer-based instrument. A microprocessor calculates speed and distance while perform vehicle tests. To begin the test on a set of tires, the driver makes one practice run to gain familiarity with the characteristics of the tires and to warm the brakes. At least six additional runs are then made and the results are recorded. Typically, 60 mph is used for dry braking. At a predetermined point, marked with a pylon, the driver applies the brakes and brings the vehicle to a stop as quickly as possible. The driver then records the initial speed and stopping distance that are displayed on the microprocessor. After completing the test for one set of tires, the driver records comments on a worksheet. Generally, the driver should try to maintain a ±1 mph variation about the target speed. Six speeds and stopping distances for each tire set are reported. A corrected stopping distance for each run is calculated.
Test Method Description—ISO28580 Rolling Resistance Method
The purpose of this test was to measure rolling resistance and revolutions per mile under one load/pressure combination for 30 minutes at 80 kilometers per hour. The results are corrected to a 2 meter road wheel. Results are reported both with and without skim measurement.
While the present subject matter has been described in detail with respect to specific exemplary embodiments and methods thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art using the teachings disclosed herein.
The present application claims priority under 35 U.S.C. § 119 to Provisional Application No. 62/016,710, filed Jun. 25, 2014.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US15/37070 | 6/23/2015 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62016710 | Jun 2014 | US |
