Patent Publication Number: US-2019176522-A1

Title: Tire

Description:
TECHNICAL FIELD 
     The present invention relates to a tire with a plurality of belt layers outside a carcass in a tire radial direction. 
     BACKGROUND ART 
     A tire has various advantages compared to a metal wheel and is superior to the metal wheel, for example in noise level, acceleration, deceleration and riding comfort. Accordingly, the tire is used in not only for an automobile but also for a new traffic vehicle (in subway, mono-rail, new traffic system, etc.). Moreover, conventionally, a pneumatic tire, as the tire used in the new traffic vehicle, has been known in which a plurality of belt layers with steel cords are arranged in a tread part(see Patent Literature 1). 
     However, in the conventional tire described in the Patent Literature 1, a tread rubber is directly overlapped and arranged on the belt layers, therefore, there is room for improvement from a viewpoint of more reliable protection for the plurality of belt layers. Moreover, for example in a tire for the new traffic vehicle, uneven wear or chunk (braking, peeling) is likely to be caused in the tread rubber, and the tread rubber is worn during travelling. The tire may be exchanged according to a state of the tread rubber. However, if the tire is used until wear of the tread rubber is reached the belt layer, the belt layer (for example the end of the belt layer) would be exposed. Even in such a case, it is necessary to suppress exposure of the belt layer to protect the belt layer. 
     In the new traffic vehicle travelling along rail, if the tire is travelled while the belt layer is exposed, steel cords in the belt layer would come into contact with the rail. As a result, heat is generated in the belt layer by a friction between the steel cord and the rail. Therefore, in the new traffic vehicle travelling on the rail, it is required to suppress exposure of the belt layer and avoid a contact between the belt layer and the rail, to reduce a temperature rise etc. of the tire. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Patent Laid-Open No. H10-16511 
     SUMMARY OF INVENTION 
     Technical Problem 
     The present invention has been made in view of the above-described conventional problems and an object is to protect the plurality of belt layers so that exposure of the belt layers is suppressed. 
     Solution to Problem 
     The present invention is a tire comprising: a carcass arranged between a pair of bead parts, a plurality of belt layers including a circumferential belt layer with a cord extending along a tire circumferential direction and arranged outside the carcass in a tire radial direction, at least one protective layer with an organic fiber cord extending along the tire circumferential direction and arranged outside the plurality of belt layers in the tire radial direction and in the tire width direction, and a tread rubber arranged outside the protective layer in the tire radial direction. The circumferential belt layer is provided at least at the outermost side in the tire radial direction in the plurality of belt layers. An end of the protective layer is arranged on the inner side in the tire radial direction than the plurality of belt layers, in a region outer in the tire width direction than an outermost end of the plurality of belt layers located at the outermost side in the tire width direction. 
     Advantageous Effects of Invention 
     According to the present invention, the plurality of belt layers of the tire is protected so that exposure of the belt layers can be suppressed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view of a tire of a present embodiment. 
         FIG. 2  is a plain view of the tire of the present embodiment. 
         FIG. 3  is a sectional view of the tire showing an enlarged X-part in  FIG. 1 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of a tire of the present invention will be described with reference to the drawings. 
     The tire of the embodiment is a tire for main wheel of a new traffic vehicle and is used to the tire travelling type of the new traffic vehicle. Moreover, gas is filled in the tire and inner pressure of the tire is adjusted to a prescribed pressure. Here, the tire is a nitrogen filled tire in which gaseous nitrogen is filled. 
       FIG. 1  is a sectional view of a tire  1  of the present embodiment schematically showing a structure of the tire cut along a tire width direction H.  FIG. 2  is a plain view of the tire  1  of the present embodiment showing a tread part  10  of the tire  1  viewed from an outside in a tire radial direction K.  FIG. 2  shows a tread pattern of the tread part  10  as well as an inner structure of the tread part  10  which is schematically shown. 
     As shown, the tire  1  is provided with the tread part  10  in contact with a track of line (here, rail), a pair of bead parts  11  arranged inside the tread part  10  in the tire radial direction K, and a pair of side wall parts  12  each arranged between an end of the tread part  10  and the bead part  11 . Tire equator CL is located at a center part of the tread part  10  in the tire width direction H. Moreover, the tire  1  is provided with a tread rubber  20 , a carcass  30  arranged between the pair of bead parts  11 , bead cores  31  arranged in the bead parts  11 , a plurality of belt layers  5 ( 5 A,  5 B) arranged in the tread part  10 , and at least one protective layer  6  arranged between the belt layers  5  and the tread rubber  20 . 
     The tread rubber  20  is a part of the tread part  10  (outer peripheral part) in contact with the rail and arranged outside of the protective layer  6  in the tire radial direction K. A predetermined tread pattern is formed on the tread rubber  20  of the tread part  10 . The tire  1  is provided with a plurality of main grooves  21  formed in a zig zag shape, a plurality of land parts  22  extending in a tire circumferential direction S, and a plurality of sipes  23  formed in each land part  22 . 
     The plurality of the main grooves  21  are circumferential grooves extending in the tire circumferential direction S and formed at intervals in the tire width direction H. The plurality of the land parts  22  are convex parts and divided by the plurality of the main grooves  21 . The plurality of sipes  23  are formed at a predetermined interval in the tire circumferential direction S such that they extend in the tire width direction H while being inclined at a same angle each other to the tire width direction H. 
     The carcass  30  has a plurality of cords extending along the radial direction and is toroidally arranged between the bead cores  31  of the pair of bead parts  11 . Moreover, the carcass  30  is folded back around the bead core  31 , passed through the inner side of the bead core  31  in the tire radial direction K and arranged outwardly in the tire radial direction K. The bead core  31  is annularly formed and arranged inside of the carcass  30  folded back in the bead part  11 . 
     The plurality of belt layers  5  have a plurality of cords  40  ( 40 A,  40 B) and are arranged outside the carcass  30  in the tire radial direction K. The cords  40  are metal cords formed of metal and are arranged in parallel in each belt layer  5 . The plurality of belt layers  5  include at least one inclined belt layer  5 A, at least one circumferential belt layer  5 B and are arranged to be overlapped in the tire radial direction K. The inclined belt layer  5 A has cords  40 A extending with inclination (inclined cord) to the tire circumferential direction S and the circumferential belt layer  5 B has cords  40 B extending along the tire circumferential direction S (circumferential cords). 
     The inclined belt layer  5 A is provided at least at the innermost side in the tire radial direction K in the plurality of belt layers  5 . The cords  40 A of the inclined belt layer  5 A are at the angle of 45 to 55 degrees (see inclined angle G) to the tire circumferential direction S and arranged in parallel with inclination to the tire circumferential direction S. The circumferential belt layer  5 B is provided at least at the outermost side in the tire radial direction K in the plurality of belt layers  5 . The cords  40 B of the circumferential belt layer  5 B are at the angle of to 5 degrees (0±5 degrees) to the tire circumferential direction S and arranged in parallel while extending along the tire circumferential direction S. The angle of the cord  40  is an angle between an extending direction of the cord  40  and the tire circumferential direction S. 
     The tire  1  is provided with at least four belt layers  5  comprised of the inclined belt layer  5 A and the circumferential belt layer  5 B as the plurality of belt layers  5 . Here, the plurality of belt layers are comprised of one inclined belt layer  5 A arranged outside the carcass  30  in the tire radial direction K and four circumferential belt layers  5 B arranged outside the inclined belt layer  5 A in the tire radial direction K. The inclined belt layer  5 A is provided inside in the tire radial direction K in the plurality of belt layers  5  and arranged between the carcass  30  and the circumferential belt layer  5 B. The circumferential belt layer  5 B is provided outside in the tire radial direction K in the plurality of belt layers  5  and arranged between the inclined belt layer  5 A and the protective layer  6 . 
     A width of the inclined belt layer  5 A in the tire width direction H is wider than a width of the circumferential belt layer  5 B in the tire width direction H. Therefore, the inclined belt layer  5 A is arranged to outwardly extend over the circumferential belt layer  5 B in the tire width direction H. Ends of the inclined belt layer  5 A located at both outsides in the tire width direction H are the outermost ends  5 C of the plurality of belt layers  5  in the tire width direction H and arranged on the outer side in the tire width direction H than the ends of the circumferential belt layer  5 B. The outermost ends  5 C of the plurality of belt layers  5  are located at the outermost positions in the tire width direction H among the ends of the plurality of belt layers  5 . 
     The cord  40  of the belt layer  5  is a steel cord formed of steel. Moreover, the cord  40 A of the inclined belt layer  5 A is a strait cord linearly extending to a direction inclined to the tire circumferential direction S. The cord  40 B of the circumferential belt layer  5 B is a wave-shaped cord meanderingly extending along the tire circumferential direction S, and spirally arranged along the tire circumferential direction S. An extending direction of the cord  40 B is a direction to a centerline of vibration (amplitude) of the cord  40 B, and the center line of the cord  40 B extends along the tire circumferential direction S. The cord  40 B extends along the tire circumferential direction S as a whole while meandering in a wave shape. 
     The protective layer  6  has a plurality of organic fiber cords  41  (circumferential cord) extending along the tire circumferential direction S, and is arranged outside the plurality of belt layers  5  in the tire radial direction K and in the tire width direction H. The organic fiber cords  41  are cords formed of organic fibers and are arranged in parallel in the protective layer  6 . The protective layer  6  covers whole the plurality of belt layers  5  from the outside in the tire radial direction K and from the outside in the tire width direction H to protect the plurality of belt layers  5 . Here, the tire  1  is provided with two protective layers  6  arranged to be overlapped with the circumferential belt layers  5 B. The two protective layers  6  are arranged to be overlapped with each other in the tire radial direction K. 
     The organic fiber cord  41  of the protective layer  6  is a nylon fiber cord formed of nylon fiber (here, nylon 6,6 fiber). Moreover, the organic fiber cords  41  are at the angle of 0 to 5 degrees (0±5 degrees) to the tire circumferential direction S and arranged in parallel while extending along the tire circumferential direction S. An angle of the organic fiber cord  41  is an angle between an extending direction of the organic fiber cord  41  and the tire circumferential direction S. The organic fiber cord  41  is a strait cord extending linearly along the tire circumferential direction S and spirally arranged along the tire circumferential direction S. To suppress distortion due to difference in cord angle to tire circumferential direction S between the belt layers  5  and the protective layers  6 , the protective layers  6  (cord angle: 0 to 5 degrees) are arranged outside the outermost circumferential belt layer  5 B (cord angle: 0 to 5 degrees) in the tire radial direction K. 
     A width of the protective layers  6  in the tire width direction H is wider than a width of the plurality of belt layers  5  in the tire width direction H. Therefore, the protective layers  6  are arranged to outwardly extend over the plurality of belt layers  5  in the tire width direction H. Ends  6 A of protective layer  6  located at both outsides in the tire width direction H are arranged on the outer side in the tire width direction H than the outermost ends  5   c  of the plurality of belt layers  5  and arranged in an outer region  13  of the tread part  10 . The outer region  13  is a region outer than the outermost end  5 C in the tire width direction H. In the outer side in the tire width direction H than the circumferential belt layer  5 B, the protective layers  6  are curved inwardly in the tire radial direction K and gradually shifted inwardly in the tire radial direction K. Moreover, in the outer region  13 , the ends  6 A of the protective layers  6  are arranged on the inner side in the tire radial direction K than the plurality of belt layers  5  and the outermost ends  5   c.    
       FIG. 3  is a sectional view of the tire  1  showing an enlarged X-part in  FIG. 1 . 
     As shown, the outermost end  5 C of the plurality of belt layers  5  is arranged at a location spaced apart the protective layer  6 . The shortest distance R between the outermost end  5 C and the protective layer  6  is 2 mm to 13 mm (2≤R≤13). In the section of the tire  1  in the tire width direction H, when a minimum circle P which has its center at the outermost end  5 C and contacts with the protective layer  6  is set, the radius of the circle P is the shortest distance R. 
     When the shortest distance R is less than 2 mm (R&lt;2), distortion of rubber would become large between the outermost end  5 C and the protective layer  6 , which would likely to effect on a separation-resistance performance at the outermost end  5 C. Whereas, when the shortest distance R is over 13 mm (13&lt;R), the protective layer  6  approaches to an outer surface  14  of tire  1  and it would be feared that sufficient thickness of the tread rubber  20  between the protective layer  6  and the outer surface  14  could not be obtained. As a result, if the tread rubber  20  is affected by shallow flaws, cracks would likely to be progressed between the tread rubber  20  and the protective layer  6  and to cause a separation. When the shortest distance R is 2 mm to 13 mm, distortion of rubber would be suppressed from becoming large and the separation-resistance performance at the outermost end  5 C would be surely maintained. Furthermore, sufficient thickness of the tread rubber  20  between the protective layer  6  and the outer surface  14  would be maintained, thus occurrence of separation could be suppressed. 
     The end  6 A of the protective layer  6  is arranged at a location spaced apart the outer surface  14  of the tire  1 . The shortest distance T between the end  6 A of the protective layer  6  and the outer surface of the tire  1  is 5 mm to 15 mm (5≤T≤15). In the section of the tire  1  in the tire width direction H, when a minimum circle Q which has its center at the end  6 A of the protective layer  6  and contacts with the outer surface  14  of the tire  1  is set, the radius of the circle Q is the shortest distance T. 
     When the shortest distance T is less than 5 mm (T&lt;5), when the tread rubber  20  is damaged by chunk, etc., the end  6 A of the protective layer  6  is easily exposed. Whereas, when the shortest distance T is over 15 mm (15&lt;T), the end  6 A of the protective layer  6  approaches to the carcass  30  and it would be feared that sufficient thickness of rubber between the end  6 A of the protective layer  6  and carcass  30  could not be obtained. As a result, distortion of rubber between the end  6 A of the protective layer  6  and the carcass  30  would become large, it is feared that the separation would be occurred. When the shortest distance T is 5 mm to 15 mm, even if the tread rubber  20  is damaged, the end  6 A of the protective layer is hard to be exposed. Furthermore, sufficient thickness of rubber between the end  6 A of the protective layer  6  and carcass  30  would be maintained, thus occurrence of separation could be suppressed. 
     According to the tire  1  described above, the plurality of belt layers  5  can be protected by the protective layer  6  arranged to cover the belt layers  5 . Moreover, the separation of the belt layers  5  can also be suppressed by the protective layer  6 . Even if the tread rubber  20  is damaged by uneven wear or chunk, etc., exposure of the belt layers  5  can be suppressed by the protective layer  6 . By exposure of the protective layer  6 , it is possible to recognize a state of the tread rubber  20  and request to exchange the tire  1 . Even if the protective layer  6  comes into contact with the rail, since the cord of the protective layer  6  is the organic fiber cord  41 , heat generation due to a friction between the protective layer  6  and rail can be reduced and a temperature rise of the tire  1  can be suppressed. 
     Since the organic fiber cord  41  of the protective layer  6  extends along the tire circumferential direction S, an end of the organic fiber cord  41  is easily arranged at a position other than the end  6 A of the protective layer  6 . As a result, the end  6 A of the protective layer  6  becomes hardly separable, thus occurrence of separation at the end  6 A could be suppressed. The circumferential belt layers  5 B are provided at the outermost side in the tire radial direction K in the plurality of the belt layers  5 , and the circumferential belt layer  5 B and the protective layer  6  are arranged to be overlapped with each other. Moreover, the cord  40 B of the circumferential belt layer  5 B extends along the tire circumferential direction S like the organic fiber cord  41  of the protective layer  6 . Accordingly, during rolling of the tire  1 , difference in movements of the protective layer  6  and the circumferential belt layer  5 B can be decreased and distortion of rubber between the protective layer and the circumferential belt layer  5 B can be reduced. 
     In addition, a plurality of inclined belt layers  5 A may be provided in the plurality of belt layers  5 . Moreover, one circumferential belt layer  5 B may be provided in the plurality of belt layers  5 , and a plurality of circumferential belt layers  5 B (for example, two layers or three layers) may be provided in the plurality of belt layers  5 . The plurality of circumferential belt layers  5 B are arranged to be overlapped with each other in tire radial direction K between the inclined belt layer  5 A and the protective layer  6 . 
     The tire  1  may be provided with one protective layer  6 , the tire  1  may be provided with the plurality of protective layers  6 . When the protective layer  6  is comprised of one layer, the end  6 A of the protective layer  6  is an end of one protective layer  6  located outside in the tire width direction H. When the protective layer  6  is comprised of the plurality of layers, the end  6 A of the protective layer  6  is an end of the stacked plurality of protective layers  6  located outside in the tire width direction H. 
     The organic fiber cord  41  of the protective layer  6  may be formed of organic fiber (for example, polyester fiber, rayon fiber, aramid fiber) other than nylon fiber. The protective layer  6  may be bended inwardly in the tire radial direction K in the outer region  13 . In this case, a bending position of the protective layer  6  is located at the outer side in the tire width direction H than the outermost side  5 C of the belt layers  5 . 
     REFERENCE SIGNS LIST 
     
         
           1  tire 
           5  belt layer 
           6  protective layer 
           10  tread part 
           11  bead part 
           12  side wall part 
           13  outer region 
           14  outer surface 
           20  tread rubber 
           21  main groove 
           22  land 
           23  sipe 
           30  carcass 
           31  bead core 
           40  cord 
           41  organic fiber cord