JP2008037138A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire improving a problem that a crack causes the breakage of a carcass, even when pinch cut is generated, especially the crack is generated at a lower part of a rim protect bar. <P>SOLUTION: In the pneumatic tire 1 having the rim protect bar portion 4, a cord reinforcing layer 5 is provided inside of the rim protect bar portion 4. On a surface of the rim protect bar portion 4 within a range projecting the width of the cord reinforcing layer 5 on a rim flange side by making a projecting direction match with a tire diametrical direction, or on a surface of the protect bar portion 4 on the outer side in a tire width direction than a position which the cord reinforcing layer is extended in the tire diametrical direction and at an outer position in a tire diametrical direction than the maximum width position of the rim protect bar portion 4, at least one groove-shaped recessed portion 6 or 7 extending in a tire circumferential direction is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire.

  Conventionally, when driving on poorly maintained roads, etc., when the tire falls into a large asphalt hole etc., the tire deforms greatly at a stretch, and the side part of the tire is sandwiched between the corner of the road surface and the rim. In some cases, the tire side portion is cracked, that is, a so-called pinch cut occurs.

  The generation and progression of this crack may cause the air in the tire to leak and make it impossible to run until it has cut the internal carcass.

  For the purpose of improving such problems, the shape of the pneumatic tire, the diameter of the rim flange, the curved surface shape, etc. in a state where the rim is assembled and the normal internal pressure is filled are specified. (Patent Document 1), however, such a proposal is not a solution to the problem by improving the tire itself, but is a response combined with the rim flange to be assembled with the rim, and is not a solution to the problem with the tire. It is a thing.

  In addition, for the purpose of providing a pneumatic tire capable of protecting the rim flange from the curb stone even when contacting the curb with a large impact force, the reinforcing layer is provided on the rim protect bar in the pneumatic tire having the rim protect bar. It is proposed to embed in the rim protect bar so as to extend in the thickness direction of the rim protect bar, and preferably embed the reinforcing layer along at least the rim flange side surface of the rim protect bar, more preferably It has been proposed to embed a reinforcing layer along the entire surface of the rim protect bar (Patent Document 2).

  However, in the invention described in Patent Document 2, the rim protect bar is provided with a reinforcing layer and has a reinforcing / protective effect on the entire rim protect bar. In the point of preventing carcass cutting due to the progress of cracks, the effect is poor.

There is also a proposal to protect the rim flange by using a combination of soft rubber and hard rubber inside the rim protection bar (Patent Document 3), but this proposal also has a reinforcing effect on the entire rim protection bar. However, at the time of pinch cutting, once a crack occurs, the crack may progress in the carcass direction, and the effect is poor in terms of preventing carcass cutting due to the progress of the crack.
JP-A-2005-289123 JP 2003-146026 A JP 2005-145319 A

  In view of the above-described points, the object of the present invention is improved when the pinch cut occurs, particularly when the crack is generated in the lower part of the rim protect bar, and the inconvenience that the crack causes the carcass to be cut is improved. The object is to provide a pneumatic tire.

  The pneumatic tire of the present invention that achieves the above-described object has the following configuration (1).

(1) In a pneumatic tire having a rim protect bar portion, a cord reinforcing layer is provided inside the rim protect bar portion, and the width of the cord reinforcing layer is projected on the rim flange side with the projection direction as the tire radial direction. On the surface of the rim protect bar portion inside or outside in the tire width direction from the position where the cord reinforcing layer is extended in the tire radial direction and outside in the tire radial direction from the maximum width position of the rim protect bar portion A pneumatic tire characterized in that at least one groove-like recess extending in the tire circumferential direction is provided on the surface of the rim protect bar portion at a position.

  In the pneumatic tire according to the present invention, more preferably, the pneumatic tire has a specific configuration described in any one of the following (2) to (10).

(2) The pneumatic tire according to the above (1), wherein rubbers having different moduli are used on the inner side and the outer side in the tire radial direction with the cord reinforcing layer as a boundary.

(3) The difference in the modulus values of the rubbers having different moduli used on the inner side and the outer side in the tire radial direction is 50% or more in terms of the difference in 100% modulus value. The described pneumatic tire.

(4) A rubber having different hardness according to JISK6253 durometer hardness test (A type) is used between the inner side and the outer side in the tire radial direction with the cord reinforcing layer as a boundary. The pneumatic tire according to any one of (1) to (3) above.

(5) The difference in hardness value of the rubbers having different hardnesses used on the inner side and the outer side in the tire radial direction is 5 points or more in terms of the hardness value according to the JISK6253 durometer hardness test (A type). The pneumatic tire as described in (4) above, wherein

(6) The length of the cord reinforcing layer in the tire width direction is 20% to 80% of the length in the width direction from the bead heel portion to the maximum width position of the rim protect bar portion. The pneumatic tire according to any one of 1) to (5).

(7) The air according to any one of (1) to (6), wherein a cord arrangement angle of the cord reinforcing layer is an angle of 40 ° or more and 90 ° or less with a tire axial direction. Enter tire.

(8) The installation position in the tire width direction of the groove-shaped recess provided in the lower portion of the rim protect bar portion is set at the center within a range in which the width of the cord reinforcing layer is projected on the rim flange side with the projection direction being the tire radial direction. The pneumatic tire according to any one of (1) to (7) above, wherein

(9) The pneumatic tire according to any one of the above (1) to (8), wherein the groove-shaped recess has a recess width of 1 mm or more and 2 mm or less.

(10) The pneumatic tire as described in any one of (1) to (9) above, wherein the groove-shaped recess has a recess depth of 1 mm or more and 2 mm or less.

  According to the first aspect of the present invention, even when a pinch cut occurs, particularly in a case where a crack is generated in the lower portion of the rim protect bar, at least provided at a specific location on the surface of the rim protect bar portion. By concentrating stress on one groove-like recess, a crack starts from the groove-like recess, and the crack is directed to the cord reinforcing layer provided in the direction in which the crack proceeds. Therefore, it is possible to prevent the crack from reaching the carcass and to prevent the occurrence of inconvenience that the crack causes carcass cutting.

Hereinafter, the pneumatic tire of the present invention will be described in more detail.
The pneumatic tire according to the present invention is a pneumatic tire having a rim protect bar portion, in which a cord reinforcing layer is provided inside the rim protect bar portion, and the width of the cord reinforcing layer is projected to the rim flange side in the tire radial direction. On the surface of the rim protect bar within the projected range, or outside in the tire width direction from the position where the cord reinforcing layer is extended in the tire radial direction and in the tire radial direction from the maximum width position of the rim protect bar Further, at least one groove-like concave portion extending in the tire circumferential direction is provided on the surface of the rim protect bar portion at the outer position.

  The structure of this pneumatic tire will be described with reference to the drawings. FIG. 1 is a partial sectional schematic view in the meridian direction for explaining the structure near the rim protect bar portion in the pneumatic tire according to the present invention. 2 is a partial cross-sectional schematic view in the meridian direction for explaining the structure of the periphery including the vicinity of the rim protect bar portion shown in FIG.

  1 and 2, a pneumatic tire 1 according to the present invention has a cord reinforcing layer 5 inside a rim protect bar portion 4 at a lower portion of a sidewall portion 2. 3 is a carcass, 10 is a bead core, and 11 is a bead heel.

  Whether the pneumatic tire of the present invention is provided with at least one groove-like recess 6 on the surface of the rim protect bar portion 4 within a range in which the width of the cord reinforcing layer 5 is projected on the rim flange side with the projection direction as the tire radial direction. Alternatively, on the surface of the rim protect bar portion outside the position where the cord reinforcing layer 5 is extended in the tire radial direction and outside the maximum width position of the rim protect bar portion 4 in the tire width direction. At least one groove-like recess 7 extending in the tire circumferential direction is provided.

  As described above, by providing at least one groove-like recess 6 or 7 at a specific location, even when the pinch is cut, particularly in a case where a crack is generated in the lower portion of the rim protect bar, By concentrating stress on at least one groove-shaped concave portion provided at a specific location on the surface of the rim protect bar portion, a crack starts from the groove-shaped concave portion, and in the direction in which the crack proceeds. Since the crack is directed to the provided cord reinforcing layer portion, it is possible to prevent the crack from reaching the carcass, and it is possible to prevent inconvenience that the crack causes carcass cutting. Further, the impact from the upper part of the rim protect bar 4 causes a crack only on the outer side of the cord reinforcing layer due to the presence of the groove-shaped recess on the outer side of the cord reinforcing layer 5.

  In the pneumatic tire of the present invention, the provision of the groove-like recesses makes it possible to reduce the width of the cord reinforcing layer compared to the case where no groove-like recesses are present, thereby reducing the weight of the tire. The cord also has an effect of improving comfort, and the cord constituting the cord reinforcing layer is preferably made of a steel cord or an organic fiber cord, and more preferably a steel cord.

  In the present invention, it is preferable that rubbers having different moduli are used on the inner side and the outer side in the tire radial direction with the cord reinforcing layer 5 as a boundary. When a crack occurs in the lower part of the rim protect bar at the time of pinch cutting, the use of rubber having a different modulus makes it difficult for the crack to progress on the inner side of the rim protect bar. That is, it is possible to prevent the crack from progressing along the interface between the two rubbers, thereby preventing the crack from progressing toward the carcass.

  When the modulus is different between the inner side and the outer side in the tire radial direction with the cord reinforcing layer 5 as a boundary, either may be higher or lower. According to the knowledge of the present inventors, the modulus value is It is important that the difference is 50% or more with a difference of 100% modulus value. The upper limit of the difference is 300%.

  Further, it is preferable that rubbers having different hardnesses according to JISK6253 durometer hardness test (A type) are used on the inner side and the outer side in the tire radial direction with the cord reinforcing layer 5 as a boundary. With this configuration, when a crack occurs in the lower part of the rim protect bar during pinch cutting, the crack progresses on the inner side of the rim protect bar by using rubber having a different rubber hardness. Can be difficult. According to the knowledge of the present inventors, the difference in rubber hardness is preferably 5 points or more in terms of the difference in hardness value according to the JISK6253 durometer hardness test (A type).

  Further, the length of the cord reinforcing layer 5 in the tire width direction (the length indicated by 8 in FIGS. 1 and 2) is the length in the width direction from the bead heel portion 11 to the maximum width position of the rim protect bar portion. It is preferably 20% or more and 80% or less of the length (the length indicated by 9 in FIGS. 1 and 2).

  Furthermore, it is preferable to use the cord reinforcing layer 5 so that the cord arrangement angle of the cord reinforcing layer 5 forms an angle of 40 ° or more and 90 ° or less with the tire axial direction. By using such an angle, a crack is generated, and even if the crack progresses in the cord width direction after being received by the cord reinforcing layer 5, it can be prevented from reaching the carcass. is there.

  Further, the installation position in the tire width direction of the groove-shaped recess 6 provided in the lower portion of the rim protect bar portion is set at the center in the range in which the width of the cord reinforcing layer is projected on the rim flange side and the projection direction is the tire radial direction. ) Region.

  In the pneumatic tire of the present invention, the groove-like recesses 6 and 7 preferably have a groove-like recess width of 1 mm or more and 2 mm or less. Moreover, it is preferable that the depth of the groove-shaped recessed part of the groove-shaped recessed parts 6 and 7 is 1 mm or more and 2 mm or less.

In the pneumatic tire of the present invention,
(1) A groove-like recess 6 provided on the surface side of the rim protect bar 4 within a range in which the width of the cord reinforcing layer 5 is projected on the rim flange side with the projection direction as the tire radial direction,
(2) On the surface of the rim protect bar portion which is outside in the tire width direction from the position where the cord reinforcing layer 5 is extended in the tire radial direction and outside the maximum width position of the rim protect bar portion 4 in the tire radial direction. A groove-like recess 7 extending in the tire circumferential direction,
Each may be provided with a plurality. By providing a plurality of groove-shaped recesses, the initial effect of the present invention can be effectively exhibited against unexpected impacts of various patterns, and the carcass can be well prevented from cracking. Is something that can be done.

Example 1, conventional products 1-3
The tires having a tire size of 225 / 45ZR1893Y were compared for pinch-cut performance at 18 × 71 / 2JJ and an air pressure of 220 kPa.

  The anti-pinch cut property enters a curb with a height of 100 mm at an angle of 45 ° at 20 km / h, and each of the conventional products 1 to 3 described in the following (1) to (4) and the example product 1 of the present invention. Five tires were used, and the depths of cracks that occurred from the bottom of the rim protect bar toward the carcass were compared.

(1) Conventional product 1: a normal pneumatic tire having no reinforcing layer in the rim protect bar and no groove-like recess under the rim protect bar;
(2) Conventional product 2: A pneumatic tire in which a reinforcing layer is provided in the rim protect bar, but no groove-like recess is provided under the rim protect bar,
(3) Conventional product 3: Pneumatic tire having a structure with different moduli on the inside and outside of the rim protect bar and having no groove-like recesses below the rim protect bar,
(4) Example 1: A steel reinforcement layer is disposed at an angle of 15 ° in the rim protection bar, a recess having a width of 1.5 mm is provided under the rim protection bar, and the inside and outside of the steel reinforcement layer are used as a boundary. The pneumatic tire according to Example 1 of the present invention in which the modulus of the rubber is varied so that the outer 100% modulus is 1/3 of the inner 100% modulus.

  The anti-pinch cut property was evaluated by determining that the crack depth generated in the tire of the conventional product 1 was 100, and the higher value was judged that the crack toward the carcass was shallow, that is, improved.

  The results of these experiments are as shown in Table 1, and the pneumatic tire of Example 1 of the present invention has a steel reinforcing layer as a starting point from a grooved recess having a width of 1.5 mm provided under the rim protect bar. The cracks are heading, and the depth of the cracks facing the carcass is 120, which is very shallow with respect to the conventional product 100, and it was confirmed that the anti-pinch cut property is excellent.

FIG. 1 is a partial cross-sectional schematic view in the meridian direction for explaining a structure in the vicinity of a rim protect bar portion in a pneumatic tire according to the present invention. FIG. 2 is a partial cross-sectional schematic view in the meridian direction for explaining the structure of the pneumatic tire according to the present invention including the vicinity of the rim protect bar portion shown in FIG.

Explanation of symbols

1: Pneumatic tire 2: Side wall part 3: Carcass 4: Rim protect bar part 5: Cord reinforcing layer 6: Grooved concave part 7: Grooved concave part 8: Length of cord reinforcing layer 5 in the tire width direction 9: Bead heel Length in width direction from portion 11 to maximum width position of rim protect bar portion 10: Bead core 11: Bead heel

Claims (10)

  In the pneumatic tire having the rim protect bar portion, a cord reinforcing layer is provided inside the rim protect bar portion, and the width of the cord reinforcing layer is within the range projected on the rim flange side with the projection direction as the tire radial direction. It is on the surface of the rim protect bar part or on the outer side in the tire width direction than the position where the cord reinforcing layer is extended in the tire radial direction and on the outer side in the tire radial direction than the maximum width position of the rim protect bar part A pneumatic tire characterized in that at least one groove-like recess extending in the tire circumferential direction is provided on the surface of the rim protect bar portion.   2. The pneumatic tire according to claim 1, wherein rubbers having different moduli are used on the inner side and the outer side in the tire radial direction with the cord reinforcing layer as a boundary.   3. The pneumatic tire according to claim 2, wherein a difference in modulus value between rubbers having different moduli used on the inner side and the outer side in the tire radial direction is 50% or more in terms of a difference in 100% modulus value. tire.   The rubber having different hardness according to JISK6253 durometer hardness test (A type) is used between the inner side and the outer side in the tire radial direction with the cord reinforcing layer as a boundary. The pneumatic tire according to any one of 1 to 3.   The difference between the hardness values of the rubbers having different hardnesses used on the inner side and the outer side in the tire radial direction is a hardness value difference of 5 points or more according to a durometer hardness test (A type) of JIS K6253. The pneumatic tire according to claim 4.   The length of the cord reinforcing layer in the tire width direction is 20% or more and 80% or less of the length in the width direction from the bead heel portion to the maximum width position of the rim protect bar portion. The pneumatic tire according to any one of the above.   The pneumatic tire according to any one of claims 1 to 6, wherein a cord arrangement angle of the cord reinforcing layer is an angle of 40 ° or more and 90 ° or less with a tire axial direction.   The installation position in the tire width direction of the groove-shaped recess provided in the lower portion of the rim protect bar portion is the center in the range in which the width of the cord reinforcing layer is projected on the rim flange side with the projection direction being the tire radial direction. The pneumatic tire according to any one of claims 1 to 7, wherein   The pneumatic tire according to any one of claims 1 to 8, wherein the groove-like recess has a recess width of 1 mm or more and 2 mm or less.   The pneumatic tire according to claim 1, wherein the groove-shaped recess has a recess depth of 1 mm or more and 2 mm or less.

Images