JP2008279796A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of ensuring satisfactory riding comfortableness and improving resistance to side cut without increasing its weight. <P>SOLUTION: This pneumatic tire 10 is constituted by providing a carcass layer 16 with a carcass main body 18 extended toroidally between bead cores 11a and a pair of right and left folding-back parts 20 passing through inner sides in the radial direction of the tire of the bead cores 11a and extended toward the outside in the radial direction of the tire from the carcass main body 18 to indicate the direction of mounting of the pneumatic tire on a vehicle clearly. In this pneumatic tire 10, a steel belt layer 21 is provided between a crown part 16a of the carcass main body 18 and a tread part 12, and a terminal A of the outer folding-back part 20a positioned on an outer side of the vehicle is positioned between the crown part 16a and the steel belt layer 21 and a terminal B of the inner folding-back part 20b positioned on an inner side of the vehicle is positioned in a side wall part 14 among the pair of folding-back parts 20 while this pneumatic tire 10 is mounted on the vehicle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire.

As this type of pneumatic tire, a pair of right and left bead portions, a tread portion disposed on the outer side in the tire radial direction of the bead portion and having a tread surface portion of the tire, both ends in the tire width direction and the bead portion of the tread portion A pair of left and right sidewall portions that connect the outer ends in the tire radial direction, and inside each of the bead portion, the sidewall portion, and the tread portion, there is a carcass layer that extends continuously over these portions. The carcass layer is provided with a carcass body extending in a toroidal shape between bead cores embedded in a pair of left and right bead portions, and from the carcass body toward the tire radial outside through the inside of the bead core in the tire radial direction. A configuration including a pair of left and right folded portions extending in a known manner is known.
In recent years, pneumatic tires have been provided in which the inner diameter of the bead portion is increased and the flatness ratio is reduced.
However, in such a pneumatic tire, when overcoming the step, an outer side wall located on the outer side of the vehicle among the pair of left and right side wall portions between the step and the flange portion of the rim for attaching the pneumatic tire to the vehicle. There is a risk that a so-called side cut is likely to occur in which the portion is sandwiched and the carcass layer embedded in the portion breaks.
Therefore, as a means for solving such a problem, conventionally, the number of carcass layers is increased, or as shown in, for example, Patent Document 1 below, the ends of each of the pair of left and right folded portions reach the tread portion. It has been proposed to adopt a so-called envelope structure.
JP 2004-42736 A

  However, in the conventional pneumatic tire, the spring constant in the tire radial direction is increased, which not only hinders a good riding comfort but also increases the overall weight, which may deteriorate the fuel consumption. It was.

  The present invention has been made in consideration of such circumstances, and provides a pneumatic tire capable of ensuring good ride comfort and improving side cut resistance without increasing weight. With the goal.

In order to solve the above-described problems and achieve such an object, the pneumatic tire of the present invention includes a pair of left and right bead portions and a tire tread surface portion disposed radially outward of the bead portions. And a pair of left and right sidewall portions connecting the tire width direction both ends of the tread portion and the tire radial direction outer end of the bead portion, and the bead portion, the sidewall portion, and the tread portion. A carcass layer that extends continuously over each of these parts is provided inside each of the carcass body, and the carcass layer extends from the carcass body between the bead cores embedded in the pair of left and right bead parts, respectively. A pair of left and right folded portions extending outward in the tire radial direction through the tire radial inner side of the bead core, and the mounting direction to the vehicle is clearly indicated The pneumatic tire is provided with a steel belt layer between the crown portion and the tread surface portion of the carcass body, and the pneumatic tire is mounted on the vehicle in the pair of folded portions. A terminal end of the outer folded part located outside is located between the crown part and the steel belt layer, and a terminal end of the inner folded part located inside the vehicle is located in the sidewall part. And
According to the present invention, the end of the outer folded portion is located between the crown portion and the steel belt layer, and the end of the inner folded portion is located on the sidewall portion. Among the wall portions, it is possible to increase the bending rigidity of the outer side wall portion in which the outer folded portion is present without increasing the bending rigidity of the inner side wall portion in which the inner folded portion is present. Accordingly, it becomes possible to suppress an increase in the spring constant and the total weight of the pneumatic tire in the radial direction of the tire, thereby ensuring a good ride comfort and improving side cut resistance without deteriorating fuel consumption. be able to.

Here, in the carcass main body, the peripheral length from the tire equator in the outer portion located on the vehicle outer side than the tire equator when the pneumatic tire is mounted on the vehicle is on the vehicle inner side than the tire equator. It may be shorter than the peripheral length from the tire equator portion in the inner portion located at.
In this case, since the peripheral length of the outer portion is shorter than that of the inner portion, the bending rigidity of the outer sidewall portion can be further improved, and the side cut resistance is reliably improved. Can do.

Further, among the pair of left and right sidewall portions, a plurality of cords are provided inside the outer folded portion outside the outer width portion in the outer sidewall portion located outside the vehicle with the pneumatic tire mounted on the vehicle. There may be provided a reinforcing cord layer in which is embedded.
In this case, since the reinforcing cord layer is provided, the bending rigidity of the outer side wall portion can be further improved.

  According to the present invention, it is possible to ensure good ride comfort and improve side cut resistance without increasing the weight.

Hereinafter, an embodiment of a pneumatic tire according to the present invention will be described with reference to FIG.
In the pneumatic tire 10 of the present embodiment, as shown in FIG. 1, a tread having a pair of left and right bead portions 11 and a tread portion 12 of the tire 10 that is disposed outward in the tire radial direction of the bead portions 11. A portion 13 and a pair of left and right sidewall portions 14 that connect both end portions 13a of the tread portion 13 in the tire width direction H and the radially outer ends of the bead portions 11 are provided. An explicit portion (not shown) that clearly indicates the mounting direction of the vehicle is formed on the outer surface of the pneumatic tire 10.

  Here, first and second carcass layers 15 and 16 extending continuously over the respective parts are embedded in each of the bead part 11, the sidewall part 14, and the tread part 13. The first and second carcass layers 15, 16 are formed in a toroidal shape between bead cores 11 a embedded in a pair of left and right bead portions 11, and in the tire radial direction of the carcass main bodies 17, 18. A pair of left and right folded portions 19 and 20 extending from the side ends 17a and 18a through the inside of the bead core 11a in the tire radial direction and outward in the tire radial direction are provided.

In the illustrated example, the tire radial direction inner ends 17a and 18a of the carcass bodies 17 and 18 pass through the inner ends in the tire width direction H of the bead core 11a and extend in parallel with the tire width direction H. Located on the top.
Further, in the carcass bodies 17 and 18, the second carcass layer 16 is disposed on the inner surface side of the pneumatic tire 10 with respect to the first carcass layer 15, and in the folded portions 19 and 20, the second carcass layer 16 is the first carcass layer 16. It is arranged on the outer surface side of the pneumatic tire 10 with respect to the layer 15.

  In the present embodiment, the steel belt layer 21 is provided between the crown portion 16 a of the second carcass layer 16 and the tread surface portion 12. In the illustrated example, the steel belt layer 21 is disposed outward in the tire radial direction from the crown portion 15 a of the first carcass layer 15. The steel belt layer 21 has a two-layer structure in which a first steel cord layer 22 and a second steel cord layer 23 are laminated in the tire radial direction. Further, in each of the steel cord layers 22 and 23, steel cords extending in directions inclined with respect to the tire width direction H and the tire circumferential direction in the creeping direction orthogonal to the tire radial direction are inclined in the creeping direction. It is embedded in a state in which a plurality are arranged at intervals in a direction orthogonal to the direction. Then, with the steel cord layers 22 and 23 being laminated in the tire radial direction as described above, the steel cords embedded in the steel cord layers 22 and 23 cross each other in a plan view of the tread portion 12. It is supposed to be.

  In the illustrated example, the first and second steel cord layers 22 and 23 are continuously provided over the entire circumference in the tire circumferential direction with the respective center portions in the width direction positioned on the tire equator CL. Has been placed. Further, the second steel cord layer 23 is disposed outside the first steel cord layer 22 in the tire radial direction. Further, the first steel cord layer 22 is wider than the second steel cord layer 23.

A belt reinforcing layer 24 is provided between the steel belt layer 21 and the tread surface portion 12 to cover the entire area of the steel belt layer 21 from the outside in the tire radial direction. In the belt reinforcing layer 24, a plurality of organic fiber cords extending in the tire circumferential direction are embedded in a state where a plurality of organic fiber cords are arranged at intervals in the tire width direction H. Further, the belt reinforcing layer 24 is continuously arranged over the entire circumference in the tire circumferential direction in a state where the center portion in the width direction is positioned on the tire equator portion CL. Further, the belt reinforcing layer 24 is wider than the steel belt layer 21.
In the present embodiment, both end portions in the tire width direction H of the belt reinforcing layer 24 are separately provided between the tread surface portion 12 and the belt reinforcing layer 24 from the outer side in the tire radial direction over the entire circumference in the tire circumferential direction. A pair of left and right belt end reinforcing layers 25 is provided.

In the present embodiment, of the pair of left and right folded parts 20 included in the second carcass layer 16, the terminal A of the outer folded part 20 a located on the vehicle outer side in a state where the pneumatic tire 10 is mounted on the vehicle is A terminal end B of the inner folded portion 20b located between the crown portion 16a and the steel belt layer 21 and located inside the vehicle is located at the sidewall portion 14.
In the illustrated example, the end A of the outer folded portion 20 a of the second carcass layer 16 is located in the end portion 13 a outside the vehicle of the both end portions 13 a of the tread portion 13. Further, the end A is located between the crown portion 15 a of the first carcass layer 15 and the steel belt layer 21. The outer folded portion 20a reaches the vehicle outer end portion 13a of the tread portion 13 from the bead portion 11 through an outer side wall portion 14a described later.
On the other hand, in the first carcass layer 15, the terminal ends C of the pair of left and right folded portions 19 are located on the sidewall portions 14. In the example shown in the figure, the end C of the first carcass layer 15 is located more inward in the tire radial direction than the end B of the second carcass layer 16.

Further, in the present embodiment, in the carcass body 18 of the second carcass layer 16, in a state where the pneumatic tire 10 is mounted on the vehicle, from the tire equator portion CL in the outer portion located outside the tire equator portion CL. The peripheral length of the tire (hereinafter referred to as “first peripheral length”) is the peripheral length from the tire equator portion CL (hereinafter referred to as “second peripheral length”) at the inner portion located on the vehicle inner side than the tire equator portion CL. ”).
The first peripheral length is preferably 120% to 145% of the second peripheral length, for example.

  Further, in the present embodiment, of the pair of left and right sidewall portions 14, the outer folded portion of the second carcass layer 16 in the outer sidewall 14a located outside the vehicle with the pneumatic tire 10 mounted on the vehicle. A reinforcing cord layer 26 in which a plurality of cords are embedded is provided outside the tire width direction H from 20a. The reinforcing cord layer 26 is provided in an annular shape around the axis of the pneumatic tire 10. The inner peripheral edge of the reinforcing cord layer 26 in the tire radial direction is located on the outer side in the tire radial direction than the end C of the first carcass layer 15.

 In addition, the reinforcement cord layer 26 is not provided in the inner side wall part 14b located in the vehicle inner side in the state which mounted | worn the pneumatic tire 10 in the vehicle among the left-right paired side wall parts 14. FIG. The plurality of cords embedded in the reinforcing cord layer 26 are, for example, steel cords that extend continuously around the axis and are arranged at intervals in the tire radial direction. Further, the reinforcing cord layer 26 is provided in the thinnest portion of the outer sidewall portion 14a.

 As described above, according to the pneumatic tire 10 according to the present embodiment, of the pair of left and right folded portions 20 included in the second carcass layer 16, the end A of the outer folded portion 20 a is the second carcass layer 16. Since the end B of the inner folded portion 20b is located on the sidewall portion 14 and located between the crown portion 16a and the steel belt layer 21, the inner sidewall of the pair of left and right sidewall portions 14 It is possible to increase the bending rigidity of the outer sidewall portion 14a without increasing the bending rigidity of the portion 14b. Accordingly, it is possible to suppress an increase in the spring constant in the tire radial direction and the total weight of the pneumatic tire 10, and to ensure good ride comfort and improve side cut resistance without deteriorating fuel consumption. can do.

In the present embodiment, since the first peripheral length is shorter than the second peripheral length, the bending rigidity of the outer side wall portion 14a can be further improved, and the side cut resistance is ensured. Can be improved.
Further, in the present embodiment, since the reinforcing cord layer 26 is provided, it is possible to further improve the bending rigidity of the outer side wall portion 14a.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, as shown in FIG. 2, the pneumatic tire 10 shown in FIG. 1 may be configured without the first carcass layer 15.

 Furthermore, instead of this, for example, the carcass layer has a laminated structure of three or more layers, and among these carcass layers, the pair of left and right folded portions is the outermost in the tire width direction H, that is, on the outer surface side of the pneumatic tire 10. The terminal end of the outer folded portion of the outermost carcass layer is positioned between the crown portion of the carcass layer and the steel belt layer 21, and the terminal end of the inner folded portion is positioned on the inner sidewall portion 14b. In addition, the end of each of the pair of left and right folded portions in the other carcass layer may be positioned on the sidewall portion 14.

In the embodiment, the reinforcing cord layer 26 is provided. However, the reinforcing cord layer 26 may not be provided.
Furthermore, although the first peripheral length is shorter than the second peripheral length, for example, both lengths may be equal to each other.

Next, a verification test related to the above-described operational effects will be described.
First, a pneumatic tire used for this test will be described.
As a conventional example, in the pneumatic tire 10 shown in FIG. 1, the end B of the inner folded portion 20 b of the second carcass layer 16 is the same as the end A of the outer folded portion 20 a of the second carcass layer 16. A pneumatic tire that is positioned between the crown portion 16a of the second carcass layer 16 and the steel belt layer 21 at the end portion 13a in the tire width direction H and that does not have the reinforcing cord layer 26 is employed.
The pneumatic tire 10 shown in FIGS. 1 and 2 was employed as Examples 1 and 2, respectively.
The sizes of the pneumatic tires in the conventional example and Examples 1 and 2 were all 225 / 40R18.

When these pneumatic tires are separately mounted on a vehicle, and the vehicle is repeatedly advanced from the front at an angle of 75 ° toward the curb with a height of 80 mm at a speed of 5 km / h to get over the curb and the carcass layer breaks. The number of repetitions was counted. Then, the number of repetitions was compared for each pneumatic tire, and evaluation was performed with an index where the number of repetitions counted in the conventional pneumatic tire was 100.
In addition, the above-mentioned three types of pneumatic tires were attached to the vehicle separately, and the ride comfort when the vehicle was run was evaluated by the feeling of the driver. In this evaluation, the evaluation was performed using an index with the riding comfort of the conventional pneumatic tire as 100.
The results are shown in Table 1.

From this table, it was confirmed that in the pneumatic tire 10 of Example 1, it was possible to improve both the side cut resistance and the ride comfort and to reduce the weight as compared with the conventional example. . Moreover, in the pneumatic tire of Example 2, it was confirmed that the ride comfort could be improved and the weight could be reduced while maintaining the same side cut resistance as compared with the conventional example. It was.
From the above, it was confirmed that the pneumatic tires of Examples 1 and 2 can improve the side cut resistance without securing a good riding comfort and increasing the weight.

  The side cut resistance can be improved without securing a good ride comfort and without increasing the weight.

In one embodiment concerning the present invention, it is a sectional view of a pneumatic tire. In other embodiment which concerns on this invention, it is sectional drawing of a pneumatic tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 11 Bead part 11a Bead core 12 Tread part 13 Tread part 13a End part of tread part 14 Side wall part 14a Outer side wall part 16 2nd carcass layer (carcass layer)
16a Crown part 18 Carcass body 20 Folded part 20a Outer folded part 20b Inner folded part 21 Steel belt layer 26 Reinforcement cord layer A End of outer folded part B End of inner folded part CL Tire equatorial part H Tire width direction

Claims (3)

A pair of left and right bead portions, a tread portion disposed outside the tire radial direction of the bead portion and having a tread surface portion of the tire, both ends in the tire width direction of the tread portion, and an outer end in the tire radial direction of the bead portion; And a pair of left and right sidewall portions connecting the two,
Inside each of the bead part, the sidewall part and the tread part, a carcass layer continuously extending over these parts is provided,
The carcass layer extends in a toroidal manner between bead cores embedded in a pair of left and right bead parts, and extends from the carcass body through the inside of the bead core in the tire radial direction and outward in the tire radial direction. A pair of left and right folded portions,
It is a pneumatic tire that clearly shows the mounting direction to the vehicle,
A steel belt layer is provided between the crown portion of the carcass body and the tread portion,
Of the pair of folded portions, the end of the outer folded portion located on the vehicle outer side is located between the crown portion and the steel belt layer in a state where the pneumatic tire is mounted on the vehicle, and on the vehicle inner side. The pneumatic tire is characterized in that the end of the inner folded portion is located in the sidewall portion. The pneumatic tire according to claim 1,
In the carcass body, when the pneumatic tire is mounted on the vehicle, the peripheral length from the tire equator in the outer portion located outside the tire equator is located inside the vehicle from the tire equator. A pneumatic tire characterized in that it is shorter than the peripheral length from the tire equator in the inner part. The pneumatic tire according to claim 1 or 2,
Among the pair of left and right side wall portions, a plurality of cords are embedded inside the outer side turn portion of the outer folded portion in the outer side wall portion located outside the vehicle with the pneumatic tire mounted on the vehicle. A pneumatic tire provided with a reinforcing cord layer.

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