Abstract:
A tire includes first and second laterally spaced sides and a tread interposed between the first and second sides. The tread includes a tread surface having at least one groove therein, the at least one groove including facing, first and second sidewalls separated by a groove bottom surface. A first pocket region of recessed serrations extends over at least a portion of the first sidewall and a second pocket region of recessed serrations extends over at least a portion of the second sidewall. The serrations of the first and second pocket regions are staggered in a circumferential direction relative to one another.

Description:
BACKGROUND 
       [0001]    The disclosure relates to an automotive tire, and specifically to a tread thereof. It finds application in a tire that exhibits improved traction, namely engagement of snow in the tread, desired hydroplane performance, handling, and reduced noise generation, and will be described with reference thereto. However, one will appreciate that the exemplary embodiments as shown and described below are amenable to other like applications and that may use one or more of the predicted performance benefits. 
         [0002]    Commonly owned U.S. Pat. No. 6,986,372—Below discloses a tire in which at least selected grooves have serrated sidewalls. Specifically, all or a major portion of the surface of the sidewalls facing the groove includes the serrations. The serrations terminate short of a groove base or bottom surface. Tires employing these features have met with commercial success. Likewise, commonly owned U.S. Ser. No. 14/049,675, filed 9 Oct. 2013, discloses a tire tread with angled rib groove walls. 
         [0003]    There is a continued need for improved performance such as traction, noise, handling, control, braking, etc., and particularly in connection with improved performance in snow without adversely impacting hydroplane resistance. 
       BRIEF DESCRIPTION 
       [0004]    A tire with improved performance in snow is disclosed. 
         [0005]    The tire includes first and second laterally spaced sides. A tread is interposed between the first and second sides, and the tread includes a tread surface having at least one groove therein, the at least one groove including facing, first and second sidewalls separated by a groove bottom surface, and a first pocket region of recessed serrations extending over at least a portion of the first sidewall and a second pocket region of recessed serrations extending over at least a portion of the second sidewall, the serrations of the first and second pocket regions being staggered in a circumferential direction relative to one another. 
         [0006]    In an exemplary embodiment, the serrations of the first and second pocket regions partially overlap in the circumferential direction relative to one another. 
         [0007]    In one arrangement, the serrations in the first and second regions extend substantially perpendicular to the groove bottom surface. 
         [0008]    The serrations extend over less than a full height of their associated pocket region, or over substantially a same height as their associated pocket region. 
         [0009]    The serrations are circumferentially spaced from one another in their associated pocket region. 
         [0010]    The serrations extend at an angle between 0 and 180 degrees relative to the groove bottom surface and/or relative to a bottom wall of the associated pocket. 
         [0011]    At least one of the serrations is interleaved with another one of the serrations. 
         [0012]    A cross-section of the serration varies as the serration extends over a height of the pocket region. 
         [0013]    A face of the first pocket region extends at an angle relative to the groove bottom surface that is different than an angle at which the first sidewall extends relative to the groove bottom surface, and preferably at an angle less than that of the first sidewall. 
         [0014]    The serrations in a first pocket region decrease in height in the circumferential direction. 
         [0015]    End walls of the first pocket region are either parallel or non-parallel to one another. 
         [0016]    The sidewalls of the groove are disposed at a non-perpendicular first angle relative to the bottom surface of the groove, and a circumferentially extending face of the pocket region is disposed at a non-perpendicular second angle relative to the bottom surface of the groove where the first angle is greater than the second angle. 
         [0017]    The serrations do not protrude into the groove. 
         [0018]    Serrations on opposite sidewalls of the groove are disposed in opposite directions from one another. 
         [0019]    A height of the first pocket region changes as the first pocket region extends in the circumferential direction, and a height of the serrations changes as the serrations extend in the circumferential direction. 
         [0020]    A primary benefit is improved tire performance, particularly in snow. 
         [0021]    Still another advantage is associated with increased traction force from gripping a rib of snow in the contact patch of the tread. 
         [0022]    Yet another feature is improved interlocking grip features without adversely interrupting water flow through a circumferential groove of the tire. 
         [0023]    Still another benefit is a reduction in standing waves and an associated reduction in noise generation. 
         [0024]    Still other benefits and features of the present disclosure will become apparent upon reading and understanding the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a perspective view of a tire includes one or more grooves that include pockets having serrations therein. 
           [0026]      FIG. 2  is an enlarged front plan view of a portion of the tire of  FIG. 1 . 
           [0027]      FIG. 3  is an enlarged plan view of one of the tire grooves shown in  FIGS. 1 and 2 . 
           [0028]      FIG. 4  is a perspective view of the tire groove of  FIG. 3 . 
           [0029]      FIG. 5  is an enlarged view of the pocket and serrations in a groove sidewall. 
           [0030]      FIG. 6  is a plan view of the pocket and serrations in the groove sidewall. 
           [0031]      FIG. 7  is a cross-sectional view through a pocket of the groove sidewall. 
           [0032]      FIG. 8  is a table of representative dimensional values associated with the features shown in  FIG. 9 . 
           [0033]      FIG. 9  is a plan view similar to  FIG. 6  of an alternate arrangement of serrations. 
           [0034]      FIG. 10  is a plan view similar to  FIGS. 6 and 9  of another arrangement of serrations. 
           [0035]      FIG. 11  is a plan view of a groove with an alternative arrangement of serrations in pockets of the groove sidewalls. 
           [0036]      FIG. 12  is a perspective view of one of the sidewalls shown in  FIG. 11 . 
           [0037]      FIG. 13  is an enlarged view of one of the pocket and serrations in the groove sidewall of  FIGS. 11-12 . 
       
    
    
     DETAILED DESCRIPTION 
       [0038]      FIGS. 1 and 2  generally illustrate a tire or pneumatic tire  100  that includes a first or outer side  102  and a second or inner side  104  that extend between a tread surface  106 . For ease of illustration and understanding, selected portions of the sides  102 ,  104  are shown in broken line since those features are generally conventional and form no part of the present disclosure. Disposed between the first and second sides  102 ,  104  is a tire tread  110 . The tread  110  is formed in a desired pattern and the pattern or tire tread design may differ depending on various needs and end uses as will be appreciated by one skilled in the art. Therefore, many of the illustrated features of the tread  110  will not be described since they form no part of the present disclosure, and instead the description will focus on those features associated with this disclosure. 
         [0039]    More particularly, there are two central grooves  112  that extend in a circumferential direction around the tire. In addition, first and second outer circumferential grooves  114  further separate the tread  110  into groups of tread block portions, although a greater or lesser number of grooves and tread block portions is also contemplated. As more particularly illustrated in  FIGS. 3 and 4 , each of the grooves is defined by first and second sidewalls  116 ,  118  disposed in facing relation and separated by a groove bottom wall or surface  120 . At least one of the circumferential grooves  112 ,  114 , and preferably the first and second outer grooves  114  as shown in the illustrated embodiment, include pockets  130  provided in the sidewalls  116 ,  118  of the grooves. The pockets  130  are circumferentially spaced along the sidewall  116 , and likewise are preferably staggered relative to pockets  130  that are circumferentially spaced along the opposite, facing sidewall  118 . Stated another way, the pockets in facing sidewalls  116 ,  118  separated by a bottom surface  120  of the groove are not spaced directly across from one another. Instead, the pockets  130  are staggered so that in a preferred arrangement there is a slight circumferential overlap between the pockets ( FIG. 3 ). The degree of staggering or circumferential overlap may vary from one tire to another so that the present disclosure is not limited to a specific amount of overlap. 
         [0040]    With continued reference to  FIGS. 1-4 , and additional reference to  FIGS. 5-6 , one exemplary design for the pocket  130  is a generally trapezoidal recess defined by end walls  132  that angle away from one another as the end walls extend outwardly away from the bottom surface  120  of the groove, i.e., the end walls diverge from one another as the end walls extend radially outward. An inner face  134  of the pocket  130  extends upwardly from a bottom surface  136  and the inner face extends at a different angle than an angle of the sidewalls  116 ,  118  of the circumferential groove. As evident in  FIG. 4 , the angle of the inner face  134  of the pocket  130  is less than the angle of the sidewall (also referred to as the draft of the groove sidewall)  116  or  118  as measured from a plane perpendicular to the bottom surface  120  of the groove. A top of the pocket may or may not coincide with the surface  106  of the tread. 
         [0041]    A series of serrations  150  are provided in each pocket  130 . The serrations  150  are preferably circumferentially spaced or spaced at a pitch within the pocket  130  between the end walls  132  (and shown here as being evenly spaced from one another between the end walls), extend upwardly from the bottom surface  136 , and in this arrangement the serrations terminate at a height below the surface  106  of the tread. Each serration  150  is formed by angled walls  152  that converge to form a peak  154 , although other cross-sections may be used. The illustrated peaks  154  extend from an intersection between the bottom surface  136  of the pocket and intersect with the face  134  of the pocket at a location inwardly of the tread surface  106 . In this manner, the serrations  150  do not extend outwardly into the cross-section of the groove where the groove is defined by the sidewalls  116 ,  118  that diverge outwardly from the bottom surface  120  of the groove. As is also evident in  FIGS. 1-4 , and more particularly in  FIGS. 5-6 , the serrations  150  extend outwardly in a generally perpendicular direction from the bottom surface  120  of the groove, and in this instance the serrations also extend in a direction substantially perpendicularly outward from the bottom surface  136  of the pocket  130  ( FIG. 6 ). 
         [0042]      FIGS. 7 and 8  provide representative dimensions in connection with the groove, sidewall  116  or  118 , pocket  130 , and serrations  150 . It will be appreciated that these dimensions are exemplary only and not deemed to be limiting. As illustrated, the groove depth GD may range from about 0.100″ to about 1.00″, where the groove depth is measured between the surface  106  of the tire tread and the bottom channel  120 . A serration depth SD ranges from approximately 0.0502″ to approximately 1.00 inches where serration depth is measured from the surface  106  of the tread to the bottom surface  136  of the pocket. A pitch A is measured between adjacent peaks of the individual serrations  150 . The pitch A may range from a minimum of approximately 0.020″ to approximately 0.750″. Dimension B represents the spacing between surface  106  of the tire tread and the location where the peaks  150  intersect with the face  134 , i.e., that dimension that the peaks are spaced from the tread surface  106 . This dimension B may range from no spacing (0.00″) to approximately 0.900″. In addition, angle C is that angle measured between the peak and a plane extending perpendicularly from the surface  106  of the tread ( FIG. 7 ). Oftentimes, this angle will be the same as that associated with the angle of the sidewall when measured relative to a plane extending perpendicularly from the bottom wall  120  of the groove. The angle C ranges from −10° to approximately 120°. Angle D is measured between the plane extending perpendicularly from the surface  106  of the tread and face  134  of the pocket  130 . 
         [0043]      FIG. 9  illustrates a modified arrangement in which some of the serrations  160 A intersect with the bottom surface  136  of the pocket  130  and extend upwardly toward the tread surface but terminate below the tread surface  106  while other serrations  160 B extend downwardly from the tread surface and terminate prior to reaching the bottom surface  136  of the pocket. Further, the serrations  160 A,  160 B are interleaved with one another to define alternating upwardly and downwardly extending serrations. In this instance, each of the peaks  154  formed by the intersecting walls  152  of the serrations are disposed generally perpendicular to the bottom surface  136  of the pocket, and likewise generally perpendicular to the bottom surface  120  of the groove. Further, the serrations  160 A,  160 B are circumferentially spaced from one another between the end walls  132 . Again, however, it is intended that the serrations  160 A,  160 B do not extend into the cross-sectional area of the groove as defined by sidewalls  116 ,  118 , and bottom wall  120 . 
         [0044]    Yet another modification is shown in  FIGS. 10-13 . Here, pockets  170  are differently shaped and may include parallel end walls  172  ( FIG. 10 ) or the end walls may diverge (see ( FIGS. 12-13 ) and a bottom wall  176  that is inclined or angled relative to the bottom surface  120  of the groove. As evident in  FIG. 10 , the serrations  180  extend upwardly from the bottom wall  176  of the pocket  170  and the serrations terminate and intersect with the face  174  of the pocket at a location spaced radially inward from the tread surface  106 . Because the peaks  184  of the serrations  180  extend generally perpendicular or normal to the bottom wall  176  of the pocket, the peaks are inclined or angled relative to the bottom surface  120  of the groove. In the embodiment of  FIG. 10 , the pocket is angled relative to normal as represented by the angle ANG. This angle ANG may range from 0° to about 75°. As best illustrated in  FIG. 13 , the serrations  180  are thus angled relative to the bottom surface  120  of the groove. 
         [0045]    It is preferred that the angles of the serrations  180  on the opposing faces  116 ,  118  of a groove be oriented in opposite directions. Further, because the serrations  180  on the opposing faces  116 ,  118  are oriented in opposite directions, the height of the serrations are different on the opposing faces in the circumferential direction. That is, the serrations  180  in a given pocket  170  increase in height on one face and decrease in height on the opposite face as one proceeds in a circumferential direction of the groove. Once again, and as perhaps most evident in  FIG. 11 , the serrations  180  provided in pockets  170  of the sidewalls  116 ,  118  are disposed in a circumferentially staggered, partially overlapping arrangement. 
         [0046]    The recessed pockets ( 130 ,  170 ) with serrations ( 150 ,  180 ) grip into a rib of snow formed in a contact patch of the tire tread. The interlocking between the serrations ( 150 ,  180 ) and the rib of snow increases the traction force from snow shear. Lengthening the serrated pockets ( 130 ,  170 ) maximizes the engagement area. Further, orienting the pockets ( 130 ,  170 ) on adjacent, facing groove walls  116 ,  118  in opposite directions relative to one another enhances the captive engagement of snow in the tread. While larger tread features may provide more interlocking and increased traction with snow shear, a potential trade-off could be hydroplane resistance due to an interrupted water flow through the main circumferential grooves. One feature of the present disclosure is that the pockets ( 130 ,  170 ) are recessed into the circumferential groove walls  116 ,  118  and the serrations ( 150 ,  180 ) do not protrude into the main channel formed by the circumferential grooves. This configuration does not significantly interrupt water flow through the circumferential groove but advantageously still provides interlocking grip features when the groove is filled with snow. Is also believed that the serrations ( 150 ,  180 ) may prevent standing waves forming and reduce generated noise. 
         [0047]    A number of modifications will be readily apparent to one skilled in the art. For example, the top of the pocket may or may not coincide with the top edge of the main groove wall. Likewise, the draft angle on a wall that incorporates the pockets/serrations can be different than the draft angle of the main groove. The depth or thickness of the serrations would necessarily vary from an increased depth or thickness adjacent the bottom of the pocket, and reduce in depth or thickness adjacent the top of the pocket. Further, a preferred form of serrations is defined by a pair of angularly disposed walls or surfaces that intersect to form the peaks. It will be appreciated that the cross-section of the serrations may vary in shape, as well as in depth or thickness as noted above. However, it is preferred that the serrations not protrude from the wall of the pocket or into the groove channel. As also briefly noted above, the pocket in the groove sidewall can adopt a wide variety of shapes, and need not be necessarily symmetric or trapezoidal as shown in the illustrated embodiments. It is also envisioned that various combinations of these features may be used, and the present disclosure should not be limited simply to the illustrated combinations of features. 
         [0048]    This written description uses examples to describe the disclosure, including the best mode, and also to enable any person skilled in the art to make and use the disclosure. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. Moreover, this disclosure is intended to seek protection for a combination of components and/or steps and a combination of claims as originally presented for examination, as well as seek potential protection for other combinations of components and/or steps and combinations of claims during prosecution. It will also be appreciated that not all of the tread features such as all of the grooves, nor all of the ribs, etc. in the illustrated tire tread, have been identified by reference numerals for ease of illustration. However, similar features or components that are repeated in the tire tread design are structurally or functionally identical or equivalent to that described above unless particularly noted otherwise.