Patent Publication Number: US-2013228261-A1

Title: Pneumatic tire

Description:
TECHNICAL FIELD 
     The present invention relates to pneumatic tires provided with an annular decoration band formed from a plurality of ridges, and a mark constituted by predetermined characters, symbols or designs, on the outer surface of a tire side portion. 
     BACKGROUND ART 
     Normally, a tire is provided with an annular decoration band extending in the circumferential direction of the tire and one or more marks on the outer surface of a tire side portion. The marks are constituted by predetermined characters, symbols or designs indicating a company or product name, size, country of manufacture, or the like. In addition to serving as decoration for the tire, prominent marks also help to distinguish the tire from other tires. Since the space for providing such a decoration band and marks is limited, a number of approaches have been taken in order to accentuate the decoration band and the marks even in a narrow space. As disclosed in Patent Literature 1, one such approach is to provide the marks within a decoration band formed from two regions with different ridge densities arranged alternately in the circumferential direction of the tire. Subtle changes in reflected light due to the difference in ridge densities accentuate the marks within the decoration band. 
     Citation List 
     Patent Literature 
     PTL 1: JP9002028A 
     SUMMARY OF INVENTION 
     (Technical Problem) 
     The decoration band as described above is formed by processing the necessary ridges by a vulcanization mold. So as not to detract from the visibility of the marks, however, the marks need to be at least a predetermined size, thus leading to an increase in the width of the decoration band and a consequent increase in the cost for processing by vulcanization mold. On the other hand, in a typical tire the carcass turns back, from the inside towards the outside in the direction of tire width, around the bead core, and the turn back end of the carcass is positioned along the tire side portion. A problem occurs in that on either side of the turn back end in the tire radial direction, an unevenness easily forms on the tire side portion, detracting from the appearance of the tire. Furthermore, in recent years, the rubber gauge of the tire side portion has tended to become thinner in order to decrease the weight of the tire, which increases the prominence of the unevenness. A strong desire therefore exists for tire improvements that address this problem. 
     It is an object of the present invention to provide a pneumatic tire comprising an annular decoration band, formed from a plurality of ridges, and one or more marks constituted by predetermined characters, symbols, or designs on the outer surface of the tire side portion, wherein high visibility of the marks is maintained without detracting from the appearance of the tire, while the manufacturing costs of the vulcanization mold are reduced. 
     (Solution to Problem) 
     The present invention provides a pneumatic tire comprising an annular decoration band formed from a plurality of ridges, and one or more marks constituted by a predetermined character, symbol or design, on an outer surface of a tire side portion, wherein: the decoration band is disposed to extend both inward and outward in a tire radial direction from a position corresponding to a turn back end of a carcass; a width of the decoration band is narrower than a maximum length of the marks in the tire radial direction; and the marks are disposed to overlap the decoration band and to protrude beyond the decoration band either inward or outward in the tire radial direction from a position of overlap with the decoration band. 
     In the above tire, in a region of overlap with the decoration band, an edge of the marks inward or outward in the tire radial direction is preferably positioned in a central region of the decoration band. 
     Note that here, the central region of the decoration band refers to a region centered on the middle of the decoration band in the direction of width thereof, extending both inward and outward in the tire radial direction, and occupying approximately 95%, or preferably approximately 80%, of the width of the decoration band. 
     The marks are preferably disposed to extend outward in the tire radial direction. 
     In a region of overlap with the decoration band, the marks are also preferably pushed further outwards from an outer surface than the ridges in the decoration band. 
     The marks are furthermore preferably bordered by protrusions, and mark-internal ridges are preferably provided within a region surrounded by the protrusions. 
     The ridges in the decoration band are also preferably slanted at an angle in a range from 30° to 60° with respect to a meridional line of the tire. 
     (Advantageous Effect of Invention) 
     According to the present invention, an annular decoration band and one or more marks are provided on the outer surface of the tire side portion, and the decoration band is disposed to extend both inward and outward in the tire radial direction from a position corresponding to the turn back end of the carcass, with the width of the decoration band being narrower than a maximum length of the marks in the tire radial direction, and the marks being disposed to overlap the decoration band. As a result, the decoration band is made sufficiently narrow, while making the unevenness on the tire side portion near the turn back end of the carcass less prominent without the need to provide a high density of ridges in the decoration band or to form the ridges in a complex pattern. Accordingly, the processing costs for the vulcanization mold to form the decoration band can be sufficiently reduced, while also yielding a lower tire weight resulting from the reduction in the number of ridges. Furthermore, the appearance of the manufactured tire is effectively prevented from being marred. Moreover, disposing the marks to protrude beyond the decoration band either inward or outward in the tire radial direction allows for the marks to be disposed to overlap both a portion that does and a portion that does not include the decoration band. The difference between the marks and the background is thus accentuated, allowing for a great increase in visibility. Hence, the manufacturing costs of the vulcanization mold can be reduced without detracting from the appearance of the tire, while also improving the visibility of the marks. 
     In a region of overlap between the marks and the decoration band in this tire, when an edge of the marks inward or outward in the tire radial direction is positioned in a central region of the decoration band, the edge of the marks inward or outward in the tire radial direction is not seen in overlap with boundary lines of the decoration band. Accordingly, this tire presents no risk of detracting from the visibility of the marks. 
     Furthermore, disposing the marks to extend outward in the tire radial direction provides room in terms of length in the circumferential direction of the tire, thus allowing for larger sized marks, which in turn yields a further substantial increase in visibility. 
     In the region of overlap between the marks and the decoration band, pushing the marks further outwards from the outer surface of the tire than the ridges in the decoration band also further accentuates the marks. 
     Accordingly, this tire even further improves the visibility of the marks. 
     Furthermore, when the marks are bordered by protrusions, and mark-internal ridges are provided within a region surrounded by the protrusions, the marks are accentuated to an even greater degree. Accordingly, this tire achieves an even further enhanced visibility of the marks. 
     When the ridges in the decoration band are slanted at an angle in a range from 30° to 60° with respect to a meridional line of the tire, then despite the rigid step occurring in the tire radial direction on either side of the turn back end of the carcass, the unevenness on the tire side portion occurring near the position corresponding to the turn back end can be made less conspicuous. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention will be further described below with reference to the accompanying drawings, wherein: 
         FIG. 1  is a partial side view and a partial enlarged view of an embodiment of a pneumatic tire according to the present invention; 
         FIG. 2  is a cross-sectional diagram showing half of the tire in  FIG. 1  along a meridional line thereof; 
         FIG. 3  is a partial side view of another embodiment of a pneumatic tire according to the present invention; and 
         FIG. 4  is an enlarged view of the principal portion of  FIG. 2 , showing the region in which the decoration band and the marks are disposed. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following describes embodiments of the present invention with reference to the drawings. 
     In  FIGS. 1 and 2 , reference numeral  1  denotes a product tire labeled  1 . The tire  1  is provided with a tread portion  2 , a pair of sidewalls  3 , a pair of bead portions  4 , a carcass  5  composed of at least one ply cord layer extending toroidally between the pair of bead portions  4 , and a belt  6  disposed between a crown region  5   a  of the carcass  5  and tread rubber  2   a . A lateral portion  5   b  of the carcass  5  turns back, from the inside towards the outside in the direction of tire width, around a bead core  4   a  located in the bead portion  4 , and a turn back end  5   c  is positioned along a tire side portion  7 . Here, the tire side portion  7  refers to a range from an outer edge of the tread portion  2  in the direction of tire width to a section of the bead portion  4  that engages with the rim. Furthermore, as shown in  FIG. 1 , a rubber gauge t of the tire side portion  7  at the turn back end  5   c  (the thickness of rubber from the ply cord to the outer surface of the tire side portion  7 ) is approximately between 1.5 mm and 3.0 mm. 
     As shown in  FIG. 1 , an annular decoration band  8  is formed on an outer surface  7   a  of the tire side portion  7  by a plurality of ridges  8   a  provided along the circumferential direction of the tire. These ridges  8   a  may extend in a straight line either parallel to or at a predetermined angle a with respect to a meridional line M of the tire, or the ridges  8   a  may form curves or the like with a predetermined curvature. 
     One or more marks  9 , constituted by predetermined characters, symbols, or designs, are also disposed on the outer surface  7   a.    
     These marks  9  are disposed either to protrude outward, as shown in  FIG. 1 , or inward, as shown in  FIG. 3 , in the tire radial direction from a position of overlap with the decoration band  8 . 
     As shown in  FIG. 2 , taking a position corresponding to the turn back end  5   c  of the carcass as a reference, the decoration band  8  is disposed to extend both inward and outward in the tire radial direction from the position corresponding to the turn back end  5   c . The width w of the decoration band  8  in the radial direction as shown in  FIG. 1  is narrower in the tire radial direction than the length of the longest of the marks  9  that are in overlap with the decoration band  8 . As a result, the unevenness occurring on the outer surface  7   a  near a position corresponding to the turn back end  5   c  can be made less conspicuous by the decoration band  8  even if the rubber gauge is made thin to a certain degree. Furthermore, the width w of the decoration band  8  can be reduced to the minimum necessary width. Note that the width w of the decoration band  8  may be approximately between 4 mm and 20 mm. 
     As shown in  FIGS. 1 and 3 , the marks  9  are disposed to overlap both a portion that does and a portion that does not include the decoration band  8 . Since both portions that have and that lack the decoration band  8  serve as the background for the marks  9 , the difference between the marks and the background is accentuated, thereby greatly increasing visibility. 
     In particular, disposing the marks  9  to extend outward in the tire radial direction from the decoration band  8 , as shown in  FIG. 1 , provides room between adjacent marks  9  when a plurality of marks  9  are disposed in the circumferential direction of the tire, thus allowing for larger sized marks  9 , which in turn yields a further substantial increase in visibility of the marks  9 . 
     In the region of overlap between the marks  9  and the decoration band  8 , by positioning an inner edge  9   a  in the tire radial direction as shown in  FIG. 1 , or an outer edge  9   b  in the tire radial direction as shown in  FIG. 3 , in a central region of the decoration band  8 , the inner edge  9   a  in the tire radial direction or the outer edge  9   b  in the tire radial direction of the marks  9  is not seen in overlap with boundary lines  8   b  of the decoration band  8  located inward and outward in the radial direction. 
     By disposing the marks  9  so that the inner edge  9   a  in the tire radial direction as shown in  FIG. 1 , or the outer edge  9   b  in the tire radial direction as shown in  FIG. 3 , is in alignment with a position corresponding to the turn back end  5   c  of the carcass  5  along the tire side portion, the unevenness occurring on the outer surface  7   a  near the position corresponding to the turn back end  5   c  is made even less conspicuous. 
     Moreover, in the region of overlap between the marks  9  and the decoration band  8 , pushing the marks  9  further outwards from the outer surface of the tire than the ridges  8   a  in the decoration band  8 , as shown in  FIG. 4 , yields a step in the direction of tire width between the marks  9  and the decoration band  8 , thus allowing for further accentuation of the boundary between the decoration band  8  and marks  9 . 
     Furthermore, when the marks  9  are bordered by protrusions  9   c , and mark-internal ridges  9   d  are provided within a region surrounded by the protrusions  9   c , the marks  9  are accentuated to an even greater degree. Here, pushing the protrusions  9   c  further outwards from the outer surface of the tire than the mark-internal ridges  9   d  allows the protrusions  9   c  effectively to prevent damage or the like to the mark-internal ridges  9   d.    
     Note that as shown by the detailed view of the decoration band  8  in  FIG. 4 , when a concavity  8   c  that is recessed inwards in the tire width direction is provided along the outer surface  7   a , and the ridges  8   a  are caused to project from the bottom of the concavity  8   c  to a projection height that is lower than the outer surface  7   a , then even when an area around the decoration band  8  scrapes against a curb or the like while the tire is in use, the ridges  8   a  are effectively protected. 
     Here, it is preferable that the ridges  8   a  be inclined with respect to the meridional line of the tire at an angle a between 30° and 60°. Here, on either side of the turn back end  5   c  of the carcass  5  in the tire radial direction, the presence of a rigid step is unavoidable. The turn back end  5   c  extends in the circumferential direction of the tire, and if the angle a is too small, the direction in which the ridges  8   a  extend approaches the direction in which the turn back end  5   c  extends, leading to the risk of cracks easily occurring in the ridges  8   a . On the other hand, if the angle α is too large, the direction in which the ridges  8   a  extend becomes nearly orthogonal to the direction in which the turn back end  5   c  extends, leading to the concern that the ridges  8   a  may not sufficiently achieve the effect of making the unevenness occurring on the tire side portion near the position corresponding to the turn back end  5   c  less conspicuous. Restricting the direction in which the ridges  8   a  extend to the above range both sufficiently strengthens the tire while effectively making the unevenness due to the existence of the turn back end  5   c  less conspicuous. 
     EXAMPLES 
     As described below, prototypes of adjusted tires  1 - 4  according to the present invention and of a reference tire serving as a conventional example were produced, and the visibility of the marks on the tires was examined by visually confirming the marks. Table 1 shows the results of such examination. Note that visibility is an index indicating the results of examining each tire, treating the results of examining the reference tire, i.e. the conventional example, as a control. A larger index indicates superior visibility. 
     The adjusted tire  1  is a 215/60R16 size tire provided with a decoration band and marks. The decoration band (having a width of 16 mm) is centered on a position of the tire side portion corresponding to the turned back end of the carcass and extends 8 mm respectively inward and outward in the tire radial direction. The marks are 20 mm long in the tire radial direction and are disposed at a position such that the inner edge of the marks in the radial direction matches the inward boundary line of the decoration band in the circumferential direction of the tire. Note that the decoration band is provided with ridges at 1.0 mm intervals in a concavity recessed 0.4 mm inwards in the tire width direction from the outer surface of the tire side portion. The marks are formed flush with the concavity in the decoration band (ridges not being provided within the marks). 
     The adjusted tire  2  is equivalent to the adjusted tire  1 , except that the marks are disposed so that the inner edge thereof in the radial direction is positioned in the center of the decoration band. 
     The adjusted tire  3  is equivalent to the adjusted tire  2 , except that the marks are caused to project from the outer surface of the tire side portion outward in the tire radial direction by 0.4 mm. 
     Furthermore, the adjusted tire  4  is equivalent to the adjusted tire  3 , except that the inside of the marks is depressed, with protrusions bordering the marks, and mark-internal ridges being formed at 0.8 mm intervals. 
     The reference tire is equivalent to the adjusted tire  1 , except that the width of the decoration band is 29 mm, and the marks are disposed within the decoration band. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Reference 
                 Adjusted 
                 Adjusted 
                 Adjusted 
                 Adjusted 
               
               
                   
                 Tire 
                 Tire 1 
                 Tire 2 
                 Tire 3 
                 Tire 4 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Visibility of 
                 100 
                 100 
                 102 
                 102 
                 105 
               
               
                 Marks 
               
               
                   
               
            
           
         
       
     
     These results clearly show that visibility at least equivalent to that of a conventional tire can be guaranteed even when the width of the decoration band is narrower than the maximum length of the marks in the tire radial direction, and the marks are disposed to protrude beyond the decoration band in the tire radial direction from a position of overlap with the decoration band (adjusted tires  1 - 4 ). 
     REFERENCE SIGNS LIST 
       1 : Product tire 
       2 : Tread portion 
       3 : Sidewall 
       4 : Bead portion 
       4   a : Bead core 
       5 : Carcass 
       5   c : Turn back end of carcass 
       6 : Belt 
       7 : Tire side portion 
       7   a : Outer surface of tire side portion 
       8 : Decoration band 
       8   a : Ridge 
       8   b : Boundary line 
       8   c : Concavity 
       9 : Mark 
       9   a : Inner edge of mark in tire radial direction 
       9   b : Outer edge of mark in tire radial direction 
       9   c : Protrusion 
       9   d : Mark-internal ridge