JP2007022330A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of attaining at least either of restraint of generation of calf edge crack or improvement of uneven wear resistance while maintaining ice and snow performance. <P>SOLUTION: In a block 5 partitioned by a peripheral groove 3 and lateral groove 4 on a tread surface of a pneumatic tire, an opening side end portion is open to only one of block wall surfaces 51, 52 in a tire width direction, and single opening carfs 53, 54 blocked in the block 5 by a blocking side end portion are formed. The single opening carfs 53, 54 positioned nearest to both end portions in the tire peripheral direction of the block 5 are formed out of protrusions 53c, 54c protruding to the central portion side in the tire peripheral direction of the block 5 at least in a calf bottom face on opening side end portion side; body portions 53a, 54a extending from a block surface to the carf bottom face in a lateral groove depth direction at the blocking side end portion. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire in which a block is formed with a plurality of one-sided open kerfs that open only on one of the block wall surfaces in the tire width direction.

  Generally, a plurality of blocks defined by a circumferential groove and a lateral groove are formed on a tread surface of a pneumatic tire mounted on a vehicle. In some of these conventional pneumatic tires, a plurality of blocks are formed with double-sided opening kerfs whose both ends are open to block wall surfaces facing each other in the tire width direction of the block. When the side opening kerf is formed in the block, the edge portion in the block increases. Therefore, in the pneumatic tire in which both-side opening kerfs are formed in the block, the braking performance on the snow road surface and the ice road surface is mainly improved by the edge effect, and the snow performance is improved.

  However, since the both-side opening kerf divides the block in the tire circumferential direction, there is a problem that the block rigidity is lowered and the block is easily deformed when a force is applied to the pneumatic tire. Therefore, in a conventional pneumatic tire, a block is formed with a one-sided opening kerf that has one end opened to one of the block wall surfaces in the tire width direction and the other end closed inside the block. As a result, both an increase in the etching effect and suppression of a decrease in block rigidity are achieved.

  Certainly, in the pneumatic tire having the one-sided opening kerf, the block is not easily deformed as compared with the pneumatic tire having the two-sided opening kerf, but the block is deformed when a large force is applied. At this time, stress concentration occurs at the other end portion that is closed inside the block of the one-side opening kerf, that is, the closed-side end portion, and there is a possibility that cracks may occur from the closed-side end portion, that is, the kerf edge.

  Moreover, also in this one side opening kerf, one edge part is opening to the block wall surface of the tire width direction of a block. Therefore, among the plurality of one-sided opening kerfs formed in this block, the rigidity of the side groove side portion located between the one-side opening kerf located at both ends in the tire circumferential direction of the block and the side groove is the other Lower than part. In particular, in the lateral groove side portion, the vicinity of one end portion of the one side opening kerf, that is, the vicinity of the opening side end portion is lower in rigidity than the other lateral groove side portion and easily deforms, so that this portion is easily worn, There was a risk of uneven wear on the block. Therefore, in the conventional pneumatic tire, a technique for improving the rigidity of the lateral groove side portion, particularly the vicinity of the opening side end portion of the one-side opening kerf in the lateral groove portion has been proposed.

  In a conventional pneumatic tire, for example, as shown in Patent Document 1, a groove bottom raised portion formed in a lateral groove is connected to an opening side end portion of a lateral groove side portion of a block adjacent in the tire circumferential direction. There is. In the conventional pneumatic tire shown in Patent Document 1, since the groove bottom raised portion connects the opening side end portion of the lateral groove side portion facing each other across the lateral groove, the rigidity of this portion is improved, thereby causing uneven wear. It suppresses.

JP-A-8-104112

  Accordingly, the present invention has been made in view of the above, and is an air that can suppress the occurrence of kerf edge cracks and / or improve the uneven wear resistance while maintaining the performance on ice and snow. The object is to provide an inset tire.

  In order to solve the above-described problems and achieve the object, according to the present invention, in a pneumatic tire having a plurality of blocks partitioned by a circumferential groove and a lateral groove on a tread surface, the block has one end portion. A plurality of one-sided opening kerfs that are open to only one of the block wall surfaces in the tire width direction and whose other end is closed inside the block are formed, and among the plurality of one-sided opening kerfs, the most in the tire circumferential direction of the block The one-sided opening kerf positioned at both ends includes a projecting part projecting toward the central part in the tire circumferential direction of the block at least on the bottom surface of the kerf on the one end side, and a lateral groove extending from the block surface to the other end side. And a main body portion extending to the bottom surface of the kerf in the depth direction.

  Further, in the present invention, in the pneumatic tire, the one-side opening kerf is further formed with a communication portion that connects the main body side end portion in the tire width direction of the protruding portion and the main body portion. To do.

  Further, according to the present invention, in the pneumatic tire having a plurality of blocks partitioned by a circumferential groove and a lateral groove on the tread surface, the block has one end opened to only one of the block wall surfaces in the tire width direction. A plurality of one-sided opening kerfs whose other end portions are closed inside the block, and are located between the one-sided opening kerf located at both ends in the tire circumferential direction of the block and the lateral groove. The lateral groove side portion to be formed has a bulging portion that bulges toward the center side in the tire circumferential direction of the block on one end side of the one-side opening kerf.

  According to the present invention, in the pneumatic tire, the plurality of one-side opening kerfs are formed such that one end of each of the adjacent one-side opening kerfs alternately opens on a block wall surface in the tire width direction. It is characterized by that.

  According to these inventions, since a plurality of one-side opening kerfs are formed in the block, the edge portion in the block increases. Therefore, the performance on ice and snow can be maintained by the edge effect.

  In addition, at one end side of the one-side opening kerf, that is, at the opening-side end part, a protrusion that protrudes to the central part side in the tire circumferential direction of the block is formed at least on the bottom surface of the kerf, and the protrusion is sandwiched between the protrusions. Of the opposing blocks, the lateral groove side portion, which is the lateral groove side, has a bulging portion that bulges toward the center in the tire circumferential direction of the block. Therefore, the rigidity in the vicinity of the opening side end portion of the one-side opening kerf can be improved compared to other portions in the lateral groove side portion. Thereby, for example, even if a force in the tire circumferential direction is applied to the block, since the vicinity of the opening side end portion of the one side opening kerf among the lateral groove side portions is difficult to deform, the other end portion of the one side opening kerf, That is, it is possible to suppress the occurrence of stress concentration due to pulling at the closing side end. Further, for example, even when a tire circumferential force is applied to the block, the vicinity of the opening side end portion of the one-side opening kerf in the lateral groove side portion is hardly deformed, and uneven wear resistance can be improved.

  In addition, the one-side opening kerf is formed with a communication part that connects the main body side end part and the main body part in the tire width direction of the protruding part, and the central part side part facing the lateral groove side part across the one-side opening kerf Is formed such that only the bulging portion is recessed toward the center in the tire circumferential direction. Therefore, for example, even if a lateral force, which is a force in the tire width direction, is applied to the block, the deformation due to the lateral force is supported by the bulging portion and the central side portion recessed by the bulging portion. It is possible to suppress the occurrence of stress concentration due to shearing at the other end of the kerf, that is, the closed end. As a result, the stress concentration at the closed end can be suppressed, so that the occurrence of kerf edge cracks can be suppressed.

  In the pneumatic tire according to the present invention, the one-sided opening kerf extends from the block surface in a lateral groove depth direction, and further includes a communication main body portion that communicates with the protruding portion. To do.

  Further, in the present invention, in the pneumatic tire, the bulging portion bulges from a midway between the block surface and the kerf bottom surface toward a central portion side in the tire circumferential direction.

  According to the present invention, the protruding portion is formed in the lateral groove depth direction from the communication main body portion formed from the block surface, and the bulging portion bulges from the middle of the block surface and the kerf bottom surface. That is, the horizontal groove side portion of the block does not bulge toward the center in the tire circumferential direction until the position where the protruding portion is formed from the block surface, that is, the position where the bulged portion bulges from the block surface. Accordingly, a decrease in the volume of the central portion side portion of the block in the vicinity of the block surface can be suppressed, so that a decrease in the rigidity of the central portion side portion can be suppressed.

  The pneumatic tire according to the present invention has a protruding portion formed at the opening side end portion of the one side opening kerf, and the lateral groove side portion of the block has a bulging portion that bulges toward the central portion side in the tire circumferential direction. The occurrence of kerf edge cracks can be suppressed while suppressing the performance degradation. In addition, uneven wear resistance can be improved while suppressing a decrease in performance on ice and snow.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following examples. In addition, constituent elements in the following description include those that can be easily assumed by those skilled in the art or that are substantially the same. In the following examples, a heavy duty pneumatic tire mounted on a truck, a bus, or the like will be described as a pneumatic tire. Since the heavy-duty pneumatic tire supports a higher load than the pneumatic tire mounted on a passenger car, the block is easily deformed, and kerf edge cracks and uneven wear are likely to occur. Therefore, when the pneumatic tire according to the present invention is used as a heavy duty pneumatic tire, the occurrence of kerf edge cracks can be remarkably suppressed, and the uneven wear resistance can be remarkably improved. In addition, you may use the pneumatic tire concerning this invention for the pneumatic tire with which a passenger car etc. is mounted | worn.

  FIG. 1 is a view showing a tread surface of a heavy duty pneumatic tire according to the present invention. FIG. 2 is a front view of the block (part A enlarged view of FIG. 1). FIG. 3 is a side view of the block. FIG. 4 is a cross-sectional view of the block in the tire width direction (cross-sectional view along BB in FIG. 2). FIG. 5 is a cross-sectional perspective view of the block in the tire width direction (CC cross-sectional perspective view of FIG. 2).

  As shown in FIG. 1, in a heavy-duty pneumatic tire 1 that is a pneumatic tire according to the present invention, a circumferential groove 3 and a lateral groove 4 are formed on a tread surface 2. The circumferential groove 3 is a groove continuous in the tire circumferential direction, and a plurality (four in the figure) are formed in the tire width direction on the tread surface 2. The lateral grooves 4 are grooves that are continuous in the tire width direction, and a plurality of the lateral grooves 4 are formed in the tire circumferential direction on the tread surface 2. Further, the lateral groove 4 has at least one of its both ends communicating with the circumferential groove 3. Here, the circumferential groove 3 is a straight groove in this embodiment, but may be a zigzag groove. Further, the lateral grooves 4 are grooves parallel to the tire width direction in this embodiment, but may be grooves inclined with respect to the tire width direction.

  The tread surface 2 is formed with a plurality of blocks 5 defined by the circumferential grooves 3 and the lateral grooves 4. As shown in FIG. 2, the block 5 has two one-side opening kerfs 53 and 54 formed in the tire circumferential direction. The one-sided opening kerf 53 has one end (hereinafter simply referred to as “opening-side end”) of both ends thereof, one of the block wall surfaces 51 and 52 of the block 5 facing in the tire width direction. The other end (hereinafter simply referred to as “closing side end”) is closed inside the block 5. The one-side opening kerf 54 has an opening-side end of the both ends thereof that opens only to the other block wall surface 52 of the block wall surfaces 51 and 52 facing each other in the tire width direction of the block 5, and the blocking-side end portion is a block. 5 is blocked. That is, the plurality of one-side opening kerfs 53 and 54 are formed in the block 5 so that the respective opening-side ends of the adjacent one-side opening kerfs 53 and 54 open alternately to the block wall surfaces 51 and 52 in the tire circumferential direction. Yes.

  As shown in FIGS. 2 to 5, the one-side opening kerfs 53 and 54 are located at both ends of the block 5 in the tire circumferential direction, and are respectively provided with main body parts 53 a and 54 a and communication main body parts 53 b and 54 b. And projecting portions 53c and 54c and communication portions 53d and 54d. The block 5 is divided into a plurality of portions by the one-side opening kerfs 53 and 54. Specifically, the block 5 includes a lateral groove side portion 55 and 56 positioned between the one side opening kerfs 53 and 54 and the lateral groove 4, and the side groove side portions 55 and 56 sandwiching the one side opening kerfs 53 and 54. Is separated by a central portion 57 that faces the center portion. Here, the lateral groove side portions 55 and 56 and the central portion side portion 57 are connected to each other between the closed end portions of the one side opening kerfs 53 and 54 and the circumferential groove 3.

  In this embodiment, two single-sided open kerfs are formed in the block 5, but the number of single-sided open kerfs formed in the block 5 is not limited and may be three or more. In this case, the protrusions are formed in the one-sided opening kerf located at both ends of the block 5 in the tire circumferential direction.

  The main body portions 53a and 54a are formed on the closing side end side of the one-side opening kerfs 53 and 54. The main body portions 53a and 54a are formed so as to extend from the block surface 5a of the block 5 to the kerf bottom surfaces 53e and 54e on the closed end side in the transverse groove depth direction. Therefore, of the lateral groove side portions 55 and 56 and the central portion side portion 57 of the block 5, the portions in the vicinity of the main body portions 53 a and 54 a, that is, the portions facing each other across the closing side end portion side of the one side opening kerfs 53 and 54, are mutually It is formed without bulging on the opposite side.

  The communication main body portions 53b and 54b are formed on the opening side end portions of the one-side opening kerfs 53 and 54. The communication main body portions 53b and 54b are formed to extend from the block surface 5a of the block 5 in the lateral groove depth direction until they communicate with the protruding portions 53c and 54c. Accordingly, of the lateral groove side portions 55 and 56 and the central portion side portion 57 of the block 5, the projecting portion 53 c from the block surface 5 a in the vicinity of the communication main body portions 53 b and 54 b, that is, on the opening side end portion side of the one side opening kerfs 53 and 54. , 54c are formed so as not to bulge out to the sides facing each other across the position communicating with 54c.

  That is, the lateral groove side portions 55 and 56 of the block 5 are arranged around the tire circumference until the position where the protrusions 53c and 54c are formed from the block surface 5a, that is, the position where the bulging portions 58 and 59 bulge from the block surface 5a. It does not bulge toward the center in the direction. Accordingly, a decrease in the volume of the central portion side portion 57 of the block 5 in the vicinity of the block surface 5a can be suppressed, so that a decrease in rigidity of the central portion side portion 57 can be suppressed. Thereby, since it can suppress that the center part side part 57 of the block 5 becomes easy to deform | transform, it can suppress uneven wear.

  The protrusions 53c and 54c are formed on the opening side end side of the one-side opening kerfs 53 and 54. The projecting portions 53c and 54c are formed so as to project from the end portions in the lateral groove depth direction of the communication main body portions 53b and 54b toward the center portion side in the tire circumferential direction. That is, the protrusions 53c and 54c are formed so as to protrude at the center side in the tire circumferential direction of the block 5 at least on the kerf bottom surfaces 53f and 54f on the opening side end side of the one-side opening kerfs 53 and 54. Accordingly, the lateral groove side portions 55 and 56 have bulging portions 58 and 59 that bulge toward the center portion side in the tire circumferential direction on the opening side end portion side. That is, the projecting portions 53c and 54c are formed in the depth direction of the lateral groove with respect to the communication main body portions 53b and 54b formed from the block surface 5a, and the bulging portions 58 and 59 are formed on the block surface 5a and the opening side end side. Bulges from the middle of the kerf bottom surface 53f, 54f. In this embodiment, the projecting portions 53c and 54c are directed from the end in the lateral groove depth direction of the communication main body portions 53b and 54b to the kerf bottom surfaces 53f and 54f on the opening side end side toward the center in the tire circumferential direction. It is comprised by the inclined surface. In other words, the bulging portions 58 and 59 are configured by a triangle whose cross-sectional shape in the tire width direction protrudes toward the center in the tire circumferential direction (portion surrounded by a solid line and a dotted line in FIG. 4).

  In addition, it is preferable that the width | variety in the tire circumferential direction of the protrusion parts 53c and 54c is 1/2 or less of the pitch in the tire circumferential direction of the one side opening kerfs 53 and 54 formed in the block 5. FIG. Furthermore, it is preferable to be within the range of 1/2 to 1/3. This is because if the ratio exceeds 1/2, the rigidity of the central portion side portion may be significantly reduced. Moreover, it is because it may become difficult to aim at the rigidity improvement of the opening side edge part vicinity of the one side opening kerf among horizontal groove side parts as it is less than 1/3.

  Moreover, it is preferable that the width | variety in the tire width direction of the protrusion parts 53c and 54c exists in the range from the obstruction | occlusion side edge part of the one side opening kerfs 53 and 54 formed in the block 5 to the circumferential groove 3. Furthermore, it is preferable that it is 1/2 or more of the circumferential direction groove | channel 3 from the obstruction | occlusion side edge part of the adjacent one side opening kerf 53,54. This is because the rigidity of the central portion side portion may be remarkably deteriorated when exceeding the range from the closed side end portion of the one side opening kerf to the circumferential groove 3. Moreover, the rigidity of the vicinity of the opening side edge part of the one side opening kerf is aimed at among the horizontal groove side parts if it is less than 1/2 of the circumferential groove 3 from the closing side end parts of the adjacent one side opening kerfs 53 and 54. This is because it may be difficult.

  The communication portions 53d and 54d are formed between the closing side end portion side and the opening side end portion side of the one-side opening kerfs 53 and 54. The communication portion 53d is formed so as to communicate the main body portion 53a and the end portion on the main body side in the tire width direction of the protruding portion 53c. Further, the communication portion 54d is formed so as to communicate the main body portion 54a with the main body side end portion in the tire width direction of the protruding portion 54c. That is, the bulging portions 58 and 59 are formed independently of the central portion side portion 57. In this embodiment, the communication portions 53d and 54d are formed by the end portions of the communication main body portions 53b and 54b in the transverse groove depth direction, the kerf bottom surfaces 53e and 54e on the closing side end side, and the kerf bottom surface on the opening side end side. Each is constituted by a right triangle connecting 53f and 54f. That is, the bulging portions 58 and 59 are constituted by triangular prisms having a cross-sectional shape of the right triangle and extending in the tire width direction (see FIG. 5).

  Next, the behavior of the block 5 due to the force applied when the heavy-duty pneumatic tire 1 according to the present invention travels on the road surface will be described. In the heavy-duty pneumatic tire 1 according to the present invention, since a plurality of one-sided opening kerfs 53 and 54 are formed in the block 5, the edge portion in the block 5 is increased, and the performance on ice and snow is maintained by the edge effect. Can do.

  First, as shown in FIG. 4, the behavior of the block 5 when a force C in the tire circumferential direction is applied to the block 5 will be described. As shown in FIG. 4, a force C in the tire circumferential direction is applied to the block 5 when a truck, a bus or the like on which the heavy duty pneumatic tire 1 according to the present invention is mounted accelerates or brakes. At this time, the lateral groove side portions 55 and 56 tend to deform in the tire circumferential direction by the force C in the tire circumferential direction. However, in the heavy-duty pneumatic tire 1 according to the present invention, the protruding portions 53c and 54c are formed at the opening side end portions of the one-side opening kerfs 53 and 54, and the blocks facing each other with the protruding portions 53c and 54c interposed therebetween. Of these, the lateral groove side portions 55, 56 on the lateral groove side have bulging portions 58, 59 that bulge toward the center side in the tire circumferential direction of the block 5.

  Accordingly, the rigidity of the lateral groove side portions 55 and 56 in the vicinity of the opening side end portions of the one side opening kerfs 53 and 54 is improved as compared with the other portions of the lateral groove side portions 55 and 56. Thereby, even if force C in the tire circumferential direction is applied to the block 5, in the lateral groove side portions 55 and 56, the vicinity of the opening side end portions of the one side opening kerfs 53 and 54 is difficult to be deformed. That is, it is possible to suppress the occurrence of stress concentration due to pulling at the closing side end (kerf edge) of the one-side opening kerfs 53 and 54. Thereby, generation | occurrence | production of a kerf edge crack can be suppressed.

  Further, as described above, even if the tire circumferential direction force C is applied to the block 5, the vicinity of the opening side end portions of the one-side opening kerfs 53 and 54 in the lateral groove side portions 55 and 56 is difficult to be deformed. The amount of slipping on the road surface in this part can be reduced. Therefore, since early wear of this portion can be suppressed, uneven wear resistance performance can be improved.

  Next, as shown in FIG. 5, the behavior of the block 5 when a lateral force D that is a force in the tire width direction is applied to the block 5 will be described. As shown in FIG. 5, a lateral force D is applied to the block 5 when a truck, a bus, or the like on which the heavy duty pneumatic tire 1 according to the present invention is traveling on a curved road or the like. At this time, the lateral groove side portions 55 and 56 or the central portion side portion 57 tends to be deformed in the tire width direction by the lateral force D. However, in the heavy-duty pneumatic tire 1 according to the present invention, the projecting portions 53c and 54c of the one-side opening kerfs 53 and 54 and the communication portions 53d and 54d communicating with the main body portions 53a and 54a are formed, respectively. A central portion 57 that faces the lateral groove portions 55 and 56 across the kerfs 53 and 54 is formed so as to be recessed toward the central portion in the tire circumferential direction only by the bulging portions 58 and 59.

  Accordingly, the lateral groove side portions 55 and 56 or the central portion side portion 57 is not distorted by the bulging portions 58 and 59 and the bulging portions 58 and 59 even if the lateral force D tries to deform in the tire width direction. The side portions 57 contact each other and support each other. That is, even if a lateral force D is applied to the block 5, the deformation due to the lateral force D can suppress the occurrence of stress concentration due to shearing at the closed end portions (kerf edges) of the one-side opening kerfs 53 and 54. . Thereby, generation | occurrence | production of a kerf edge crack can be suppressed.

  From the above, the heavy duty pneumatic tire 1 according to the present invention can suppress the occurrence of kerf edge cracks and improve the uneven wear resistance performance while suppressing the performance on ice and snow.

  Below, the implementation result of the running test with a conventional example and the heavy-duty pneumatic tire 1 concerning this invention is demonstrated. Here, each heavy load pneumatic tire used in this running test has a common tire size of 11R22.5. Each heavy-duty pneumatic tire has a tread deployment width of 232 mm, a circumferential groove depth of 20 mm, a lateral groove depth of 15 mm, a block tire circumferential length of 40 mm, and a block tire widthwise length of 35 mm. The width of the one side opening kerf in the tire circumferential direction is 0.7 mm, and the depth of the one side opening kerf is 12 mm. Further, in the evaluation in the running test, each of the heavy load pneumatic tires is assembled on a rim of 22.5 × 7.50, the air pressure is set to 700 kPa, and the heavy load vehicle (vehicle total weight 20 t) having a wheel arrangement of 6 × 2. It was carried out by attaching to. In the heavy duty pneumatic tire of “Conventional Example 2”, the width of the groove bottom raised portion in the tire width direction is 8 mm and the height is 8 mm. Further, in the “invention” heavy-duty pneumatic tire 1, the width in the tire width direction of the protrusions 53c and 54c is 10 mm, and the depth from the block surface 5a of the communication main body portions 53b and 54b is 4 mm.

  Here, as evaluation items of the running test, on-ice braking performance and on-snow braking performance, presence / absence of occurrence of kerf edge cracks, uneven wear resistance, and 50% worn WET braking performance were evaluated. The braking performance on ice is an index evaluation of the braking distance when the heavy load vehicle is braked from the speed of 40 km / h on the road surface on ice. The on-snow braking performance is an index evaluation of the braking distance when the heavy load vehicle is braked on the road surface from a speed of 40 km / h. The presence / absence of kerf edge cracks refers to the presence / absence of cracks at the closed end of the one-sided opening kerf formed on the block after the heavy load vehicle has traveled 30,000 km. Further, the uneven wear resistance performance is an index evaluation based on the difference in wear amount in one block after running the heavy load vehicle for 30,000 km as an uneven wear amount. The 50% worn WET braking performance is an index evaluation of the braking distance when the heavy load vehicle is braked from a speed of 60 km / h on a wet road surface with the block worn by 50%. In addition, the evaluation item of the said running test evaluated "conventional example 1" as "100". In addition, in the case of index evaluation, each evaluation item is better as the numerical value is higher.

  As is apparent from Table 1, the “present invention” in which the one-sided opening kerf is formed including a protruding portion, that is, the heavy duty pneumatic tire 1 according to the present invention is formed without including a protruding portion. Compared with “Conventional Example 1”, while maintaining the braking performance on ice, braking performance on snow and WET braking performance during 50% wear, the occurrence of kerf edge cracks is suppressed (“Conventional Example 1” is present, “Invention” is No), improved uneven wear resistance. Therefore, the heavy-duty pneumatic tire 1 of the “present invention” suppresses the occurrence of kerf edge cracks and is resistant to uneven wear while maintaining the performance on ice and snow as compared with the heavy-duty pneumatic tire of the “conventional example”. Can be improved.

  In addition, “Conventional Example 2” in which a plurality of one-side opening kerfs adjacent to each other in the tire circumferential direction are connected to an opening-side end portion of a horizontal groove side portion of a block by a groove bottom raised portion formed in a horizontal groove is “ Compared to Conventional Example 1 ”, the occurrence of kerf edge cracks can be suppressed (“ Conventional Example 1 ”is present,“ Conventional Example 2 ”is not present) and uneven wear resistance is improved. The performance is deteriorated, and further, the WET braking performance at 50% wear is deteriorated. Therefore, in the heavy load pneumatic tire 1 of the “present invention”, the groove bottom raised portion is formed in the horizontal groove unlike the heavy load pneumatic tire of “Conventional Example 2”, and the volume of the horizontal groove is not reduced.

  In addition, in the said Example, although the protrusion parts 53c and 54c are comprised by the inclined surface, this invention is not limited to this. FIG. 6 is a diagram illustrating another configuration example of the protruding portion of the one-side opening kerf. FIG. 7 is a diagram illustrating another configuration example of the protruding portion of the one-side opening kerf. As shown in FIG. 6, the communication main body portions 53 b and 54 b protrude from the end portions in the transverse groove depth direction to the center portion side in the tire circumferential direction and extend in the transverse groove depth direction to the kerf bottom surfaces 53 f and 54 f on the opening side end portion side. The protrusions 53g and 54g may be formed by extending. That is, the protrusions 53g and 54g may be formed so that the cross-sectional shape in the tire width direction on the opening side end portion side of the one-side opening kerfs 53 and 54 is stepped. Further, as shown in FIG. 7, a curved surface having a convex shape on the center side in the tire circumferential direction from the end in the transverse groove depth direction of the communication main body 53b, 54b to the kerf bottom surface 53f, 54f on the opening side end side. The protruding portions 53h and 54h may be configured.

  Moreover, in the said Example, although the opening side edge part side of the one side opening kerfs 53 and 54 is each formed by the communication main-body parts 54b and 54b and the protrusion parts 53c and 54c, this invention is limited to this. It is not a thing. FIG. 8 is a diagram illustrating another configuration example of the protruding portion of the one-side opening kerf. FIG. 9 is a diagram illustrating another configuration example of the protruding portion of the one-side opening kerf. As shown in FIG. 8, the inclined surface projecting toward the center in the tire circumferential direction is formed continuously from the block surface 5a on the opening side end side of the one side opening kerfs 53, 54 to the kerf bottom surfaces 53f, 54f, The protrusions 53k and 54k may be configured. Further, as shown in FIG. 9, the curved surfaces that are convex toward both end portions in the tire circumferential direction continuously from the block surface 5a on the opening side end side of the one side opening kerfs 53, 54 to the kerf bottom surfaces 53f, 54f, You may comprise the protrusion parts 53m and 54m.

  Further, in the above embodiment, the plurality of one-side opening kerfs 53 and 54 are formed in the block 5 with the respective opening-side end portions opening alternately to the opposing block wall surfaces 51 and 52 in the tire width direction. It is not limited to. For example, the plurality of one-side opening kerfs 53 and 54 may be formed in the block 5 such that the respective opening-side end portions open only to one of the block wall surfaces 51 and 52 facing each other in the tire width direction. In this case, it is preferable that three or more single-sided opening kerfs are formed in the block 5. This is because if the block 5 is formed with two single-sided opening kerfs, the rigidity of the central portion of the block 5 may be significantly reduced.

  As described above, the pneumatic tire according to the present invention is useful for heavy-duty pneumatic tires, and in particular, suppresses the generation of kerf edge cracks or improves uneven wear resistance performance while maintaining performance on ice and snow. Suitable for

It is a figure which shows the tread surface of the pneumatic tire for heavy loads concerning this invention. It is a front view (A partial enlarged view of FIG. 1) of a block. It is a figure which shows the side view of a block. It is tire width direction sectional drawing of a block (BB sectional drawing of FIG. 2). It is a tire width direction cross-sectional perspective view of a block (CC cross-sectional perspective view of FIG. 2). It is a figure which shows the other structural example of the protrusion part of the one side opening kerf. It is a figure which shows the other structural example of the protrusion part of the one side opening kerf. It is a figure which shows the other structural example of the protrusion part of the one side opening kerf. It is a figure which shows the other structural example of the protrusion part of the one side opening kerf.

Explanation of symbols

1 Pneumatic tire for heavy load 2 Tread surface 3 Circumferential groove 4 Horizontal groove 5 Block 5a Block surface 51, 52 Block wall surface 53, 54 One side open kerf 53a, 54a Main body portion 53b, 54b Communication main body portion 53c, 54c Protruding portion 53d, 54d Communication part 53e, 54e Calf bottom face 53f, 54f Calf bottom face 53g-53m, 54g-54m, Protrusion part 55, 56 Horizontal groove side part 57 Central part side part 58, 59 Swelling part

Claims (6)

In a pneumatic tire having a plurality of blocks partitioned by circumferential grooves and lateral grooves on the tread surface,
The block is formed with a plurality of one-sided open kerfs whose one end is opened only in one of the block wall surfaces in the tire width direction and whose other end is closed inside the block,
Among the plurality of one-sided opening kerfs, the one-sided opening kerf located at both ends in the tire circumferential direction of the block is
A projecting portion projecting to the center side in the tire circumferential direction of the block at least on the bottom surface of the kerf on the one end side;
A main body portion extending from the block surface to the kerf bottom surface in the transverse groove depth direction on the other end side;
A pneumatic tire characterized by being formed by.   The said one side opening kerf is extended in the horizontal groove depth direction from the said block surface, and the communication main-body part which connects the said main-body part and the said protrusion part is further formed. Pneumatic tire.   3. The pneumatic tire according to claim 1, wherein the one-side opening kerf is further formed with a communication portion that connects the main body side end portion of the protruding portion in the tire width direction and the main body portion. . In a pneumatic tire having a plurality of blocks partitioned by circumferential grooves and lateral grooves on the tread surface,
The block is formed with a plurality of one-sided open kerfs whose one end is opened only in one of the block wall surfaces in the tire width direction and whose other end is closed inside the block,
Among the blocks, the lateral groove side portion located between the one-side opening kerf located at both ends in the tire circumferential direction of the block and the lateral groove is located on one end side of the one-side opening kerf. A pneumatic tire having a bulging portion that bulges toward a central portion in a tire circumferential direction.   5. The pneumatic tire according to claim 4, wherein the bulging portion bulges from a midway between the block surface and the kerf bottom surface toward a central portion in the tire circumferential direction.   The plurality of one-side opening kerfs are formed so that one end of each of the adjacent one-side opening kerfs alternately opens on a block wall surface in the tire width direction. The pneumatic tire according to any one of the above.

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