JP5144305B2 - Bias tire - Google Patents

Description

  The present invention relates to a bias tire, and more particularly, to a bias tire having improved steering stability.

In general, it is effective to use a tread compound having a higher grip as a method for improving the steering performance of the tire, and thereby an improvement in cornering speed is expected.
Therefore, by arranging the reinforcing cord layer in the carcass layer wrapping to reinforce the tire side part, it is possible to transmit the high side force generated by improving the cornering speed from the tread part to the vehicle with as little loss as possible. (For example, refer to Patent Document 1).
JP-A-2-18105

  Conventionally, as a bias tire, a method of reinforcing the bead portion to the lower portion of the side has been taken in order to suppress the tiredness of the tire case and improve the stability when inputting the lateral force of cornering. However, since the rigidity of the shoulder part from the upper part of the side is relatively low, the rigidity difference of the side part becomes large, and the side part is locally deformed by lateral force, which is disadvantageous in terms of transient characteristics of steering stability. Met.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a bias tire that can improve steering stability during cornering and can significantly improve transient characteristics during cornering.

  The present invention has been made in view of the above-described facts, and the bias tire according to claim 1 straddles a pair of bead portions and a bead core of one bead portion to a bead core of the other bead portion in a toroidal shape. A carcass having a bias structure including two carcass plies whose end portions are folded back from the inner side of the tire to the outer side of the bead core; and a tread rubber layer that is provided on the outer side of the carcass in the tire radial direction and that constitutes the tread portion. A cord reinforcing layer including a plurality of fiber cords arranged on the tire outer surface side of the carcass from the tread portion to the bead portion and reinforcing the carcass, and when viewed in a cross section along a tire rotation axis The tread portion side of the cord reinforcing layer overlaps the tread rubber layer, and the bead portion side of the cord reinforcing layer is the above At least one of the are folded Dokoa are folded portion overlaps the carcass ply, and characterized in that.

Next, the operation of the bias tire according to claim 1 will be described.
In the bias tire according to claim 1, when a cord reinforcing layer including a plurality of fiber cords that reinforce the carcass is disposed from the tread portion to the bead portion on the outer surface side of the carcass, when viewed in a cross section along the tire rotation axis The tread part side of the cord reinforcement layer is overlapped with the tread rubber layer, and the bead part side of the cord reinforcement layer is overlapped with the folded part of at least one carcass ply where the bead core is folded. As the side part is reinforced without causing a large rigidity step on the side part, the local concentration of deformation of the side part is suppressed, so the transient characteristics of steering stability during cornering are greatly improved The

  The addition of one carcass ply can provide the same effect for reinforcing the side part, but since one additional carcass ply is added to the tire tread part, the out-of-plane bending rigidity of the tread part increases, so Worsens and leads to lower grip. Accordingly, there are two carcass plies.

  According to a second aspect of the present invention, in the bias tire according to the first aspect, the tread portion side of the cord reinforcing layer is overlapped with the tread rubber layer by 5 to 20 mm when viewed in a cross section along the tire rotation axis. It is characterized by that.

Next, the operation of the bias tire according to claim 2 will be described.
When viewed in a cross section along the tire rotation axis, the tread portion side of the cord reinforcement layer is overlapped with the tread rubber layer by 5 to 20 mm, thereby increasing the end of the cord reinforcement layer without increasing the out-of-plane bending rigidity of the tread portion. It is possible to suppress the failure caused by the part and improve the durability.

If the overlap amount is less than 5 mm, it is difficult to suppress a failure due to the end portion of the cord reinforcing layer.
On the other hand, if the amount of overlap exceeds 20 mm, the effect of suppressing the above-mentioned failure will reach a peak, and the out-of-plane bending rigidity of the tread portion may be increased.

As the fiber cord, an organic fiber cord is preferable, and an aromatic polyamide cord and a polyethylene terephthalate cord are particularly preferable.
The reason is that when the cord of the cord reinforcing layer is a steel cord, a failure due to the end portion is likely to occur, and a steering reduction due to an increase in tire weight is caused.

  As described above, according to the bias tire of the present invention, the steering stability during cornering can be improved and the transient characteristics during cornering can be greatly improved.

A bias tire 10 according to an embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the pneumatic bias tire 10 of the present embodiment is a cart tire and includes a pair of bead portions 12, and a carcass 14 straddling a toroid from one bead portion 12 to the other bead portion 12. (The illustration of the half on one side is omitted in FIG. 1).

  The carcass 14 is composed of two carcass plies 16. The carcass ply 16 is made by weaving an organic fiber cord (not shown) and coating it with a coating rubber (not shown).

  These carcass plies 16 extend from one bead core 18 embedded in one bead portion 12 to the other bead core 18 embedded in the other bead portion 12, and the end side is from the inner side in the tire axial direction of the bead core 18 to the outer side. A portion extending from one bead core 18 to the other bead core 18 is a main body portion 16A, and a portion of the bead core 18 that is positioned outside the bead core 18 in the tire axial direction is a folded portion 16B.

  The two carcass plies 16 are disposed so that the organic fiber cord of one carcass ply 16 and the organic fiber cord of the other carcass ply 16 intersect each other, and one carcass ply 16 and the other carcass ply 16 are arranged. 16, the inclination direction of the cord with respect to the tire equatorial plane CL is set in the opposite direction.

A tread rubber layer 22 constituting the tread portion 20 is disposed outside the carcass ply 16 in the tire radial direction, and a side rubber layer 26 constituting the side portion 24 is disposed outside the carcass ply 16 in the tire axial direction. Has been. An inner liner 28 is disposed on the inner surface side of the carcass 14.
A stiffener 30 for maintaining high rigidity of the bead portion 12 is disposed in an area having a substantially triangular cross-section surrounded by the main body portion 16A and the folded portion 16B.

In the pneumatic bias tire 10 of the present embodiment, a cord reinforcing layer 32 (shown by a dotted line) is disposed along the main body portion 16A on the outer surface of the main body portion 16A of the outer carcass ply 16.
The cord reinforcing layer 32 has a structure in which a plurality of cords arranged in parallel with each other are rubber-coated. The cord of the cord reinforcing layer 32 is inclined in the same direction as the cord of the inner carcass ply 16, and the inclination direction with respect to the tire circumferential direction is set to be opposite to the adjacent cord of the outer carcass ply 16. ing.

As the cord used for the cord reinforcing layer 32, an organic fiber cord is preferable, and an aromatic polyamide cord, a polyethylene terephthalate cord or the like is preferable. However, an organic fiber cord other than the above materials may be used as long as it is not a steel cord. good.

  The cord reinforcing layer 32 is disposed from the tread portion 20 to the bead portion 12, and when viewed in a cross section along the tire rotation axis, the tread portion side of the cord reinforcing layer 32 overlaps with the tread rubber layer 22. The bead portion side of the reinforcing layer 32 overlaps the folded portion 16B of each of the two carcass plies 16. In the present embodiment, the bead portion side of the cord reinforcing layer 32 is overlapped with the folded portion 16B of each of the two carcass plies 16, but in the present invention, the folded portion of at least one carcass ply 16 is used. What is necessary is just to make it overlap with 16B.

  In addition, when viewed in a cross section along the tire rotation axis, the tread portion side of the cord reinforcing layer 32 is preferably overlapped with the tread rubber layer 22 by 5 to 20 mm (overlap amount L, see FIG. 1).

(Function)
Next, the operation of this embodiment will be described.
In the bias tire 10 of the present embodiment, a cord reinforcing layer 32 including a plurality of fiber cords that reinforce the carcass 14 is disposed from the tread portion 20 to the bead portion 12 on the outer surface side of the carcass 14, and along the tire rotation axis. When viewed in cross section, the tread portion side of the cord reinforcing layer 32 is overlapped with the tread rubber layer, and the bead portion side of the cord reinforcing layer 32 is overlapped with the folded portion 16B of the carcass ply 16 where the bead core is folded. Therefore, the side portion 24 is reinforced without causing a large rigidity step in the side portion 24 from the bead portion 12 to the tread portion 20, and the local concentration of deformation of the side portion 24 is suppressed. The steering stability can be improved and the improvement of the transient characteristics during cornering is greatly improved.

When viewed in a cross section along the tire rotation axis, the tread portion side of the cord reinforcement layer 32 is overlapped with the tread rubber layer 22 by 5 to 20 mm, thereby increasing the cord reinforcement layer without increasing the out-of-plane bending rigidity of the tread portion. It is possible to suppress a failure caused by the end portion of 32 and improve durability.
If the overlap amount is less than 5 mm, it is difficult to suppress a failure caused by the end portion of the cord reinforcing layer 32. On the other hand, if the amount of overlap exceeds 20 mm, the effect of suppressing the above-mentioned failure will be peaked, and the out-of-plane bending rigidity of the tread portion may be increased.

Further, by using an organic fiber cord such as an aromatic polyamide cord or a polyethylene terephthalate cord for the cord reinforcing layer 32, it is possible to suppress the occurrence of failure due to the end of the cord reinforcing layer 32. The tire weight increase by providing 32 can be suppressed to the minimum.
Further, since the cord of the cord reinforcing layer 32 intersects the cord of the adjacent outer carcass ply 16, an interlayer shearing force that can withstand a high side force can be generated.
In the above embodiment, an example in which the present invention is applied to a cart tire has been described. However, as long as a bias tire is used, the present invention can be applied to other types of bias tires such as a passenger tire. .

(Test example)
In order to see the effect of the present invention, a cart tire of a conventional example and a cart tire of an example to which the present invention was applied were prepared and an actual vehicle running test was performed.
The tire size is 4.5 / 10.0-5 at the front and 7.1 / 11.0-5 at the rear. The rim used was 4.5-5 at the front and 8.0-5 at the rear, and the internal pressure was 80 kPa at the front and 80 kPa at the rear.

  Example Tire: A tire in which a cord reinforcing layer is provided on the outside of two carcass plies 16 as shown in FIG. The height h1 of the end portion of the folded portion 16B of the inner carcass ply 16 (the distance measured from the position where the rim diameter is measured to the outside in the tire radial direction) is 60 mm, and the height of the end portion of the folded portion 16B of the outer carcass ply 16 The height h2 is 50 mm, and the height h3 of the end portion in the tire radial direction of the reinforcing cord layer 32 is 20 mm.

  Conventional tire: As shown in FIG. 2, the specifications (h1, h2) of the two carcass plies 16 are the same as in the embodiment, but a reinforcing cord layer 34 (illustrated by a dotted line) is provided inside the folded portion 16B. Is provided. The reinforcing layer cord layer 34 extends from the bead core 18 toward the end portion of the folded portion 16B, and the height h4 of the radially outer end portion is 40 mm.

The test tires were mounted on the rear, and the front specs used for the combination were used.
Driving vehicle: KART FA class vehicle & engine Evaluation driver: KART international competition license acquisition driver Test course: Mibu International KART course.
In the test, lap time and feeling evaluation were performed.

Test results a. lap time

b. Feeling Evaluation Compared with the conventional example, the tire of the example to which the present invention was applied bent a corner at a high speed, and the behavior of the vehicle was stable even during cornering, and the tire could be bent smoothly. Also, even if traction was applied at the corner exit, the rear did not escape and could be pushed forward.

It is sectional drawing of the bias tire which concerns on one Embodiment of this invention. It is sectional drawing of the bias tire which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Bias tire 12 Bead part 14 Carcass 16 Carcass ply 16A Main body part 16B Folding part 18 Bead core 20 Tread part 22 Tread rubber layer 24 Side part 32 Cord reinforcement layer L Overlap amount

Claims (5)

A pair of beads,
A carcass having a bias structure composed of two carcass plies in which a bead core of one bead portion is straddled in a toroidal shape from a bead core of the other bead portion, and an end portion of the bead core of the bead portion is folded from the inside to the outside of the tire;
A tread rubber layer provided on the outer side in the tire radial direction of the carcass and constituting a tread portion;
A cord reinforcement layer including a plurality of fiber cords disposed on the tire outer surface side of the carcass from the tread portion to the bead portion and reinforcing the carcass;
With
When viewed in a cross section along the tire rotation axis, the tread portion side of the cord reinforcement layer overlaps the tread rubber layer, and the bead portion side of the cord reinforcement layer folds the bead core. A bias tire characterized by overlapping with a folded portion of a carcass ply. 2. The bias tire according to claim 1, wherein the tread portion side of the cord reinforcing layer overlaps the tread rubber layer by 5 to 20 mm when viewed in a cross section along the tire rotation axis. The bias tire according to claim 1, wherein the fiber cord is an organic fiber cord. The bias tire according to claim 3, wherein the fiber cord is an aromatic polyamide cord. The bias tire according to claim 3, wherein the fiber cord is a polyethylene terephthalate cord.

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