JP2011046225A - Tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire allowing compatibly achieving of cutting resistance and riding comfort. <P>SOLUTION: This pneumatic tire 10 includes a bead part 1, a carcass 5 made by twisting a plurality of cords and including a folded part 5a folded back to the tread width direction outside in the bead part 1 and a belt layer 7 arranged at the tire radial direction outside of the carcass 5. The carcass 5 includes a first region 51 including an outside end of the tire radial direction of the carcass 5 and a second region 52 continuous to the first region 51 in the folded part 5a. An inside end 51a of the first region 51 is located in the range of ≥40% and ≤60% of a tire height H1 in relation to the tire height H1 to be a height from a bead toe 1a at the tire radial direction inside of the bead part 1 up to an end part 7a at the tire radial direction outside of a tread part 4. An outside end 51b of the first region 51 is located in the vicinity of a tread width direction end part of a belt layer 7. The twisting number of cords in the first region 51 is larger than that in the second region 52. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention includes a pair of beads, a carcass formed by twisting a plurality of cords and including a folded portion that is folded back outward in the tread width direction by the beads, and a belt layer disposed on the outer side in the tire radial direction of the carcass in the tread. It relates to the tire provided.

  Conventionally, a method of changing the structure of a carcass cord for each part in order to achieve both cut resistance and ride comfort is known. For example, between the outer carcass folded by a bead and positioned on the outer side in the tread width direction, and the inner carcass positioned on the inner side of the tire than the outer carcass, the elongation of the carcass cord at a constant load, the thickness of the cord, Tires with different numbers of twisted cords are known (see, for example, Patent Document 1).

JP 2007-237922 A (page 4-6)

  However, the conventional tire described above has the following problems. That is, if the thickness of the carcass cord is locally changed, a difference in level is generated on the surface, and stress is concentrated. For example, when riding on a curb during temporary parking on the road or in and out of a parking lot, the sidewall of the tire is sandwiched between the rim flange and the curb and the outer carcass breaks, so-called resistance There was a problem that the cutability deteriorated. In addition, the structure that locally changes the elongation of the carcass cord at a constant load has a problem in that the manufacturing method is complicated and the cost is increased.

  Accordingly, an object of the present invention is to provide a tire that can achieve both cut resistance and ride comfort without incurring high manufacturing costs.

  In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention is a carcass including a pair of beads (bead portion 1) and a folded portion (folded portion 5a) which is formed by twisting a plurality of cords and is folded outward in the tread width direction by the beads. (Carcass 5) and a tire (pneumatic tire 10) including a belt layer (belt layer 7) disposed on the outer side in the tire radial direction of the carcass in the tread (tread portion 4), The folded portion includes a first region (first region 51) including an outer end of the carcass in the tire radial direction, and a second region (second region 52) connected to the first region, and the first region One end (inner end 51a) of the tire is a height from the end (bead toe 1a) of the bead in the tire radial direction to the end (end 7a) of the tread in the tire radial direction. It is located in the range of 40% or more and 60% or less of the tire height with respect to (height H1), and the other end (outer end 51b) of the first region is an end portion in the tread width direction of the belt layer. The number of twists of the cord in the first region is greater than the number of twists of the cord in the second region.

  According to such a tire, the carcass includes a first region and a second region. The number of twists of the cords in the first region is larger than the number of twists of the cords in the second region. For this reason, for example, even when riding on the curb at the time of temporary parking on the road or taking in and out of the parking lot, it is possible to suppress the breakage in the first region that receives the breaking force first. Thereby, possibility that a carcass will fracture | rupture and puncture can be made low, and what is called cut resistance can be improved.

  Further, the number of twists of the carcass cord can be reduced as a whole by the first region and the second region. For this reason, the longitudinal spring of the tire can be kept relatively small. Thereby, the fall of riding comfort can be suppressed. Furthermore, since it is sufficient to manage only the number of twisted cords at the time of manufacturing, it is possible to suppress an increase in manufacturing cost. Therefore, it is possible to provide a tire that can achieve both cut resistance and ride comfort without incurring high manufacturing costs.

  A second feature of the present invention relates to the first feature of the present invention, wherein the number of twists of the cord in the first region is 1.5 times or more the number of twists of the cord in the second region. The gist is that it is 0 times or less.

  A third feature of the present invention relates to the first or second feature of the present invention, wherein the first region and the belt layer are separated from each other, an end of the first region, and the belt layer. The gist is that the distance from the end in the tread width direction is 5 mm or more and 10 mm or less.

  According to the characteristics of the present invention, it is possible to provide a tire that can achieve both cut resistance and ride comfort without incurring high manufacturing costs.

It is sectional drawing of the tire radial direction and tread width direction of the tire by embodiment of this invention.

  Next, an embodiment of a tire according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[Embodiment]
In the present embodiment, (1) a configuration of a pneumatic tire, (2) a detailed configuration of a carcass, (3) a comparative evaluation, (4) actions and effects, and (5) other embodiments will be described.

(1) Configuration of Pneumatic Tire FIG. 1 is a cross-sectional view in the tread width direction and the tire radial direction of a pneumatic tire 10 according to an embodiment of the present invention. In FIG. 1, hatching of a partial cross section is omitted in order to clarify the position of the carcass and the like. The pneumatic tire 10 may be filled not only with air but also with an inert gas such as nitrogen gas. The pneumatic tire 10 is a tire having a low flatness and excellent so-called sports running performance such as high-speed stability performance and turning performance of the vehicle. Specifically, the flatness of the pneumatic tire 10 is set to 35% or more and 50% or less.

  As shown in FIG. 1, the pneumatic tire 10 includes a pair of beads 6, a carcass 5, and a belt layer 7 that form a skeleton of the pneumatic tire 10. The beads 6 are embedded on both sides in the tread width direction TW. The pneumatic tire 10 includes a pair of left and right bead portions 1 and a pair of sidewall portions 2 in the tread width direction TW, and a tread portion 4 continuous from both sidewall portions 2 via a buttress portion 3. The buttress portion 3 is a portion having both ends of the tread portion 4 that are in contact with the road surface and the tire maximum width portion.

  The bead 6 includes a bead core 6a and a bead filler 6b. The carcass 5 includes a folded portion 5 a formed by twisting a plurality of cords and folded back by the bead 6 to the outside in the tread width direction TW. Specifically, the carcass 5 includes a single cord layer that reinforces the bead portion 1, the sidewall portion 2, the buttress portion 3, and the tread portion 4. The belt layer 7 is disposed on the outer side in the tire radial direction of the carcass 5 in the tread portion 4. Specifically, the belt layer 7 is composed of two belt layers.

  The belt layer 7 includes a plurality of organic fiber cords extending along the tire circumferential direction. Specifically, the organic fiber cord of the belt layer 7 is made of aramid fiber, polyketone fiber, polyethylene naphthalate fiber, polyparaphenylene benzobisoxazole fiber, or at least one of composite fibers containing these. The belt layer 7 includes two belt layers. However, in the tire of the present invention, the number of belt layers constituting the belt layer 7 is not limited to this. The belt layer 7 is composed of a cord layer that extends obliquely with respect to the tire equator line CL in a tread surface view, preferably a cord layer of a steel cord, and the two belt layers are each cord constituting the belt layer 7. Are stacked so as to cross each other across the tire equator line CL.

(2) Detailed configuration of carcass Since the pneumatic tire 10 is a tire having a low flatness, the carcass 5 has a sidewall with respect to the length along the tread width direction TW of the carcass 5 located in the tread portion 4. The length of the carcass 5 located in the portion 2 along the tire radial direction TD is short. The carcass 5 has a first region 51 and a second region 52. In order to clarify the first region 51 and the second region 52, only the first region 51 is hatched in FIG. The first region 51 includes an outer end 51b of the carcass 5 in the tire radial direction TD at the turn-up portion 5a. The first regions 51 are disposed at both ends in the tread width direction TW, respectively.

  An inner end 51a of the first region 51 in the tire radial direction TD is a tire height that is a height from the inner end of the bead 6 in the tire radial direction TD to the outer end 4a of the tread portion 4 in the tire radial direction TD. It is located in the range of 40% or more and 60% or less of the height H1 with respect to H1. The tire height H1 shown here indicates the height from the bead toe 1a that is the inner end of the bead portion 1 in the tire radial direction TD to the end 4a of the tread portion 4 that is outside the tire radial direction TD. For example, the tire height H1 is set to 75 mm or more and 110 mm or less. The height from bead toe 1a to a position of 40% or more and 60% or less of tire height H1 is defined as height H2. The height H2 is more preferably set at a position 55% of H1. That is, the length from the bead toe 1a to the inner end 51a corresponds to the height H2. The tire maximum width portion is included in the range of 40% to 60% of the height H1.

  The outer end 51b of the first region 51 in the tire radial direction TD is positioned near the end of the belt layer 7 in the tread width direction TW. That is, the first region 51 ends near the end of the belt layer 7 in the tread width direction TW. The first region 51 and the belt layer 7 are separated from each other. Specifically, the distance X between the outer end 51b of the first region 51 and the end 7a of the belt layer 7 in the tread width direction TW is 5 to 10 mm.

  The second area 52 is continuous with the first area 51. The second region 52 is located on the tire inner side than the first region 51. That is, the end 52 b that is one end of the second region 52 is connected to the inner end 51 a of the first region 51. The other end of the second region 52 is connected to the carcass of the other first region located on the opposite side with respect to the tire equator line CL.

  The number of twists of the cord in the first region 51 is larger than the number of twists of the cord in the second region 52. Specifically, the number of twists of the cord in the first region 51 is 1.5 to 2 times the number of twists of the cord in the second region 52. For example, the number of twists of the cord in the second region 52 is 2 or more and 3 or less. In this case, the number of twists of the cord in the first region 51 is 3 or more and 6 or less within a range that satisfies the condition of 1.5 to 2 times the number of twists of the cord in the second region 52. . For example, the number of twists of the cord in the second region 52 is two, and the number of twists of the cord in the first region 51 is three.

(3) Comparative Evaluation Next, in order to further clarify the effects of the present invention, comparative evaluation performed using pneumatic tires according to the following comparative examples and examples will be described. Specifically, (3.1) Evaluation method and (3.2) Evaluation result will be described. In addition, this invention is not limited at all by these examples.

(3.1) Evaluation Method Using each pneumatic tire, (3.1.1) Cut resistance evaluation, (3.1.2) Longitudinal spring coefficient evaluation, and (3.1.3) Riding comfort evaluation Went. Data on pneumatic tires were measured under the following conditions.
・ Tire size: 225 / 45R18
・ Rim wheel size: 7.5J
・ Load condition: 5.00kN
・ Internal pressure: 220 kPa
・ Evaluation vehicle: FF sedan (2000 cc displacement)

  The pneumatic tire according to Conventional Example 1 and Conventional Example 2 differs from the pneumatic tire 10 described in the embodiment in that the number of twists of the carcass cord is constant.

  Moreover, the pneumatic tire according to Example 1 is the same as the pneumatic tire 10 described in the embodiment. Further, the pneumatic tires according to Examples 2 and 3 are described in the embodiment in that the number of twists of the cords in the first region 51 is larger than the number of twists of the cords in the second region 52, and the numbers are different from each other. This is different from the pneumatic tire 10.

(3.1.1) Cut resistance evaluation Evaluation method: Cut resistance was evaluated using a curbstone having a height of 5 mm, a width of 500 mm, and a triangular cross section. Specifically, the curb has a triangular prism shape, and the base of the isosceles triangle is grounded to the road surface. The angle of the triangle tip is set to 45 degrees.

  The curb was pressed against the tread surface of each pneumatic tire in the vertical direction to index the energy when the carcass cord broke. In addition, the measurement result of each pneumatic tire was displayed as an index with the cut resistance of the pneumatic tire according to Comparative Example 1 as 100. The larger the index value, the better the cut resistance.

(3.1.2) Evaluation of longitudinal spring coefficient Evaluation method: The longitudinal spring coefficient was measured for each pneumatic tire. The longitudinal spring coefficient of the pneumatic tire according to Comparative Example 1 is indicated as an index with the value being 100. A larger index value indicates a larger longitudinal spring coefficient.

(3.1.3) Evaluation of ride comfort Evaluation method: Each pneumatic tire was mounted on a vehicle, and evaluation was performed based on the feeling of the driver when traveling on a general road. In addition, the evaluation result of the comparative example was set to 100, and other evaluation results were shown as an index. An evaluation result shows that riding comfort is excellent, so that a numerical value is large.

(3.2) Evaluation Results The evaluation results of each pneumatic tire will be described with reference to Table 1.

  In the pneumatic tires according to Examples 1 to 3, evaluation of ride comfort almost equivalent to that of Conventional Example 1 was obtained. In particular, in the pneumatic tires according to Examples 1 and 2, the vertical springs were not so large, and as a result, the ride comfort was equal to or almost equivalent to that of Conventional Example 1.

  It was confirmed that the pneumatic tires according to Examples 1 to 3 have a cut resistance that is 1.5 times or more that of the pneumatic tire according to Conventional Example 1.

  Thus, it was confirmed that the pneumatic tire according to the example has the same riding comfort and good cut resistance as compared with the conventional comparative example.

(4) Action and effect
As described above, according to the pneumatic tire 10 according to the present embodiment, the carcass 5 includes the first region 51 and the second region 52. The number of twists of the cord in the first region 51 is larger than the number of twists of the cord in the second region 52. For this reason, for example, even when the vehicle rides on the curb during temporary parking on the road or in and out of the parking lot, it is possible to suppress breakage in the first region 51 that receives the breaking force first. Thereby, the possibility that the carcass 5 is broken and punctured can be reduced, and so-called cut resistance can be improved.

  Further, the number of twists of the cord of the carcass 5 can be reduced as a whole by the first region 51 and the second region 52. For this reason, the longitudinal spring of the tire can be kept relatively small. Thereby, the fall of riding comfort can be suppressed. Furthermore, since it is sufficient to manage only the number of twisted cords at the time of manufacturing, it is possible to suppress an increase in manufacturing cost. Therefore, it is possible to provide a tire that can achieve both cut resistance and ride comfort without incurring high manufacturing costs.

  In addition, when the position of the inner side edge 51a of the 1st area | region 51 is less than 40% of tire height H1, since the vertical spring of the 1st area | region 51 becomes large, riding comfort will fall large. Further, when the position of the inner end 51a of the first region 51 is larger than 60% of the tire height H1, the portion where the carcass 5 is easily broken is not reliably covered by the first region 51, and the cut resistance is reduced. Resulting in.

  In the present embodiment, the number of twists of the cords in the first region 51 is 1.5 times or more and 2.0 times or less than the number of twists of the cords in the second region 52. For this reason, it can suppress that the vertical spring of a tire becomes large too much. Thereby, riding comfort can be further improved. If the number of twists of the cord in the first region 51 is less than 1.5 times the number of twists in the cord of the second region 52, the number of twists of the cord of the carcass 5 may not be suppressed as a whole. There is sex. For this reason, there is a possibility that a decrease in ride comfort cannot be suppressed. Further, when the number of twists of the cord in the first region 51 is larger than 2.0 times the number of twists of the cord in the second region 52, the vertical spring may be too large. For this reason, there is a possibility that a decrease in ride comfort cannot be suppressed.

  In the present embodiment, the first region 51 and the belt layer 7 are separated from each other, and the distance X between the outer end 51b of the first region 51 and the end portion 7a in the tread width direction TW of the belt layer 7 is 5 mm or more. 10 mm or less. For this reason, it is possible to reliably cover the portion where the carcass 5 is easily broken by the first region 51 and to reliably prevent the belt layer 7 and the first region 51 from contacting each other. When the distance X is less than 5 mm, the belt layer 7 and the first region 51 come into contact with the rolling of the tire, and the durability may be reduced. In addition, when the distance X is greater than 10 mm, a portion where the carcass 5 is easily broken is not reliably covered by the first region 51, and cut resistance may be reduced.

  In this embodiment, the flatness of the pneumatic tire 10 is set to 35% or more and 50% or less. For this reason, the effect of this invention can be acquired suitably. In addition, when the flatness ratio of the pneumatic tire 10 is smaller than 35%, the longitudinal spring becomes large, so that ride comfort may be greatly reduced. Moreover, when the flatness ratio of the pneumatic tire 10 is larger than 50%, the carcass fracture portion is located on the bead side, and thus the effects of the present invention may not be obtained favorably.

  In the present embodiment, the tire height H1 is set to 75 mm or more and 110 mm or less. For this reason, the effect of this invention can be acquired suitably. Note that when the tire height H1 is shorter than 75 mm, the longitudinal spring becomes large, and the ride comfort may be greatly reduced. In addition, when the tire height H1 is longer than 110 mm, the carcass fracture portion is located on the bead side, and thus the effects of the present invention may not be suitably obtained.

(5) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the embodiment of the present invention can be modified as follows. In the embodiment of the present invention, the number of twists of the cords in the first region 51 may not be 1.5 times or more and 2.0 times or less than the number of twists of the cords in the second region 52.

  In the embodiment of the present invention, the distance X between the outer end 51b of the first region 51 and the end portion 7a in the tread width direction TW of the belt layer 7 may not be 5 mm or more and 10 mm or less.

  In the embodiment described above, the first regions 51 are provided at both ends in the tread width direction TW. However, the present invention is not limited to this, and the first regions 51 may be provided in any one of them. In this case, it is effective that the first region 51 is provided outside the vehicle when the pneumatic tire 10 is mounted on the vehicle.

  In the embodiment described above, the carcass 5 includes the first region 51 and the second region 52, but is not limited thereto, and may further include regions having different numbers of twists.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

CL: tire equator line, TD: tire radial direction, TW: tread width direction, X: distance, 1 ... bead part, 1a ... bead toe, 2 ... sidewall part, 3 ... buttress part, 4 ... tread part, 4a ... End portion, 5 ... carcass, 5a ... folded portion, 6 ... bead, 6a ... bead core, 6b ... bead filler, 7 ... belt layer, 7a ... end portion, 10 ... tyre, 51 ... first region, 51a ... inner end, 51b ... outer end 52 ... second region 52b ... end

Claims (3)

A pair of beads, a carcass formed by twisting a plurality of cords and including a folded portion that is folded back outward in the tread width direction by the bead, and a belt layer disposed on the outer side in the tire radial direction of the carcass in the tread. Tire,
The carcass is
In the folded portion, a first region including an outer end of the carcass in the tire radial direction;
A second region that continues to the first region,
One end of the first region is 40% of the tire height with respect to a tire height that is a height from an end portion of the bead in the tire radial direction to an end portion of the tread in the tire radial direction. Above, located in the range of 60% or less,
The other end of the first region is located near the end of the belt layer in the tread width direction,
The tire in which the number of twists of the cord in the first region is larger than the number of twists of the cord in the second region.   The tire according to claim 1, wherein the number of twists of the cord in the first region is 1.5 times or more and 2.0 times or less of the number of twists of the cord in the second region. The first region and the belt layer are separated from each other,
The tire according to claim 1 or 2, wherein a distance between an end of the first region and an end of the belt layer in the tread width direction is 5 mm or more and 10 mm or less.

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