JP6129691B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire including a belt layer, a belt reinforcing layer stacked on the outer peripheral side of the belt layer, and a tread rubber portion disposed on the outer peripheral side of the belt reinforcing layer.

  In a pneumatic tire, when a lateral force is applied during cornering traveling or the like, buckling occurs in the installation surface, and there is a problem that the tread portion is easily lifted partially from the road surface and steering stability is deteriorated.

  The surface of the tread portion of the pneumatic tire is provided with a plurality of main grooves extending along the tire circumferential direction and a land portion defined by the main grooves. During cornering, it has been found that buckling deformation is likely to occur locally in the vicinity of the shoulder main groove that divides the shoulder land portion, in particular, from the shoulder main groove to the intermediate land portion provided on the inner side in the tire width direction.

  In Patent Document 1 below, a belt reinforcing layer is spirally wound in the tire circumferential direction with a narrow strip wound, and the narrow strip is overlapped around the discontinuous region provided in the belt layer directly below the land portion. Tires are described. Patent Documents 2 and 3 below describe pneumatic tires in which a reinforcing layer is provided on the outer side in the tire width direction from the equator plane of the tire on the outer side in the tire radial direction of the belt layer.

  However, none of the patent documents consider the local buckling deformation that occurs from the shoulder main groove as described above to the land portion provided on the inner side in the tire width direction. There is a problem that steering stability cannot be suppressed and steering stability deteriorates.

  Although buckling deformation can be suppressed by increasing the rigidity of the entire belt reinforcing layer, the end of the belt layer and the end of the belt reinforcing layer are close to each other, and the rigidity in the vicinity of the end of the belt layer is reduced. Since the change becomes large, there is a problem that the strain tends to concentrate near the end of the belt layer and the rolling resistance is deteriorated.

JP-A-5-131804 JP-A-8-20204 JP 2004-322718 A

  The present invention has been made in consideration of such problems, and provides a pneumatic tire excellent in steering stability by suppressing local buckling deformation that occurs during cornering running without deteriorating rolling resistance. For the purpose.

A pneumatic tire according to the present invention includes a belt layer, a belt reinforcing layer laminated on the outer peripheral side of the belt layer, and a tread rubber portion disposed on the outer peripheral side of the belt reinforcing layer. The tread rubber portion includes a shoulder main groove, a center main groove located on the inner side in the tire width direction from the shoulder main groove, a shoulder land portion formed on the outer side in the tire width direction of the shoulder main groove, and the shoulder An intermediate land portion defined between the main groove and the center main groove, and the belt reinforcing layer includes a first region provided in the intermediate land portion, and a tire width direction outer side of the first region. A second region extending to an outer end portion in the tire width direction of the intermediate land portion; and a third region extending from the shoulder main groove to the shoulder land portion, wherein the second region includes the first region and the first region. Stiffer than region rather high, the belt reinforcing layer, characterized in that provided in the vehicle outside the tire centerline.

As a preferred embodiment of the present invention, a pneumatic tire having a designated rotation direction may be used. As another form, the first region may be terminated within the intermediate land portion. As another form, the third region may be terminated on the inner side in the tire width direction from the ground contact end. As another form, the belt reinforcing layer provided in the third region may be set to be higher in rigidity than the belt reinforcing layer provided in the first region. As another form, the first region terminates at a position separated by 30% or more of the total width of the intermediate land portion from the inner end portion in the tire width direction of the intermediate land portion, and the second region has its width Is set to 30% or more and 50% or less of the entire width of the intermediate region, and the third region terminates at a position that is 50% or less of the entire width of the shoulder land portion from the inner end portion in the tire width direction of the shoulder land portion. May be.

  According to the present invention, the belt reinforcing layer laminated on the outer peripheral side of the belt layer has the second region provided from the shoulder main groove to the intermediate land portion set to be higher in rigidity than the other regions. Buckling deformation locally generated from the main groove to the intermediate land portion can be suppressed, and steering stability during cornering traveling can be improved. In addition, since the rigidity of the belt reinforcing layer changes stepwise, the concentration of strain can be alleviated and deterioration of rolling resistance can be suppressed.

1 is a half sectional view of a pneumatic tire according to an embodiment of the present invention. It is sectional drawing which shows an example of the structure of a tread part typically. It is sectional drawing which shows an example of the structure of a tread part typically. It is sectional drawing which shows an example of the structure of a tread part typically.

  Embodiments of the present invention will be described below with reference to the drawings.

  The pneumatic tire of the present embodiment shown in FIG. 1 includes a pair of left and right bead portions 1, a pair of left and right sidewall portions 2 extending from the left and right bead portions 1 outward in the tire radial direction, and left and right sidewall portions 2. A radial tire provided with a tread portion 4 connected to the outer peripheral ends of each of the tires and a carcass layer 3 disposed so as to be bridged between a pair of bead portions 1.

  Embedded in the bead portion 1 are an annular bead core 1a formed by rubber-covering a converging body such as a steel wire, and a bead filler 1b having a triangular cross section located outside the bead core 1a in the tire radial direction.

  The carcass layer 3 is wound up so as to sandwich the bead core 1a and the bead filler 1b, and its end is locked. An inner liner for holding air pressure is disposed inside the carcass 3.

  A belt layer 5 is disposed on the outer peripheral side of the carcass layer 4 in the tread portion 4, and a belt reinforcing layer 6 is laminated on the outer peripheral side of the belt layer 5. The belt layer 5 extends to the vicinity of the grounding ends E on both the left and right sides, and is provided over the entire width of the tread portion 4. The belt layer 5 has two belt plies 5 a and 5 b laminated inside and outside, and reinforces the tread portion 4 on the outer periphery of the carcass layer 3. The belt plies 5a and 5b include steel cords extending at a predetermined angle with respect to the tire circumferential direction, and the steel cords are disposed so as to cross each other in opposite directions between the plies.

  A tread rubber layer 7 constituting the outermost peripheral surface of the tire T is disposed on the outer peripheral side of the belt reinforcing layer 6. The tread rubber layer 7 has a pair of left and right shoulder main grooves 8 extending continuously in the tire circumferential direction, and a center main groove 9 extending in the tire circumferential direction B2 provided on the inner side B2 of the shoulder main groove 8 in the tire width direction. Is provided. In the present embodiment, two center main grooves 9 arranged on both sides of the tire equator D and two shoulder main grooves 8 provided on the outer side of the tire are provided on the surface of the tread portion 4. In total, four main grooves are provided.

  A pair of left and right shoulder land portions 10 are formed on the tread rubber layer 7 of the tread portion 4 on the outer side B1 in the tire width direction of the two shoulder main grooves 8 by the four main grooves 8 and 9 described above. An intermediate land portion 11 is formed on the inner side B <b> 2 of the shoulder main groove 8 in the tire width direction, and a center land portion 12 is formed between the two center main grooves 9.

  The belt reinforcing layer 6 is formed by rubber coating a plurality of reinforcing cords arranged in parallel. The reinforcing cord extends substantially parallel to the tire circumferential direction. In this embodiment, an organic fiber cord or steel cord formed of nylon, rayon, aramid or the like is used as the reinforcing cord.

  As shown in FIG. 1, the belt reinforcing layer 6 is provided from the intermediate land portion 11 to the shoulder land portion 10 in the tread portion 4. The belt reinforcement layer 6 is partitioned into a first region 6a, a second region 6b, and a third region 6c in order from the intermediate land portion 11 to the outer side B1 in the tire width direction. The second region 6b is divided into the first region 6a and the third region. It is provided with higher rigidity than 6c.

  Specifically, the first region 6a is provided in the intermediate land portion 11, one end is connected to the second region 6b, and the other end is from the tire width direction inner end portion 11a of the intermediate land portion 11 to the tire width direction outer side B1. Terminate at a remote location. When the distance from the end portion of the first region 6a to the inner end portion 11a in the tire width direction of the intermediate land portion 11 is smaller than 30% of the total width Wm of the intermediate land portion, the groove bottom of the center main groove 9 and the intermediate land portion 11 Therefore, it is preferable that the first region 6a terminates at a position away from the inner end portion 11a of the intermediate land portion 11 by 30% or more of the entire width Wm of the intermediate land portion.

  The second region 6b extends from the outer side B1 in the tire width direction of the first region 6a to the outer end portion 11b in the tire width direction of the intermediate land portion 11 and is connected to the third region 6c. The width W2 of the second region 6b is set to 30% or more and 50% or less of the total width Wm of the intermediate land portion 11, and the second region 6b extends from the outer end portion 11b in the tire width direction of the intermediate land portion 11 to the intermediate land portion 11. It is preferable to terminate at a position not less than 30% and not more than 50% of the total width.

  The third region 6c extends from the shoulder main groove 8 to the shoulder land portion 10 and terminates from the ground contact end E on the inner side B2 in the tire width direction. The distance from the tire width direction inner end portion 10a of the shoulder land portion 10 to the tire width direction outer end portion of the third region 6c is the entire width of the shoulder land portion 10 (that is, from the tire width direction inner end portion 10a to the ground contact end E). When the length is greater than 50% of Ws, the end of the third region 6c and the widthwise end of the belt layer 5 are close to each other in the vicinity of the ground contact E, and the rigidity of the tread portion 4 is close to the ground contact E. Therefore, the strain tends to concentrate near the end of the belt layer, and the rolling resistance deteriorates. For this reason, it is preferable that the outer end portion in the tire width direction of the third region 6c is terminated at a position equal to or less than 50% of the entire width Ws of the shoulder land portion 10 from the inner end portion 10a in the tire width direction of the shoulder land portion 10.

  The first region 6a, the second region 6b, and the third region 6c are topped by, for example, aligning a plurality of reinforcing cords with a predetermined number of ends (the number of cords driven per unit width) and covering with topping rubber. Alternatively, it may be formed by being processed over the entire circumference in the tire circumferential direction so that the cord is oriented in the tire circumferential direction.

  In this case, as shown in FIG. 2, a topping counter 6-1 having a width dimension corresponding to the width from the first region 6 a to the third region 6 c on the outer peripheral side of the belt layer 5, that is, the entire width of the belt reinforcing layer 6. The first region 6a is provided at a position corresponding to the third region 6c over the entire circumference in the tire circumferential direction, and then a topping anti-6-2 having a width dimension corresponding to the width of the second region 6b is applied to the second region 6b. Even if it is provided over the entire circumference in the tire circumferential direction at the corresponding position, two toppings are stacked only in the second region 6b, and the second region 6b is provided with higher rigidity than the first region 6a and the third region 6c. Good.

  Alternatively, as shown in FIG. 3, a topping counter 6-1 having a width according to the width of the second region 6b from the first region 6a is formed on the outer peripheral side of the belt layer 5 in the first region 6a and the second region 6b. Provided at corresponding positions over the entire circumference in the tire circumferential direction, and then corresponds to the top region 6-2 having a width dimension corresponding to the widths of the second region 6b and the third region 6c, corresponding to the second region 6b and the third region 6c. Is provided over the entire circumference in the tire circumferential direction, and the two toppings 6-1 and 6-2 are stacked only in the second region 6b, and the second region 6b is higher than the first region 6a and the third region 6c. Rigidity may be provided.

  In such a case, the second layer topping anti-6-2 having a width corresponding to the width of the second region 6b and the third region 6c has a width corresponding to the width of the first region 6a to the second region 6b. Since the end of the first layer topping 6-1 on the second region 6b side is wrapped, distortion in the vicinity of the outer side in the tire width direction of the second region 6b can be alleviated, and deterioration of rolling resistance can be suppressed. .

  The belt reinforcing layer 6 is formed by winding one or a plurality of aligned cords in a spiral around the tire axis because the reinforcing cords are oriented substantially parallel to the tire circumferential direction. May be. In this case, as shown in FIG. 4, the feed pitch P2 in the tire width direction in the second region 6b is made smaller than the feed pitch P1 in the first region 6a and the third region 6c, so that the second region 6b The number of ends may be set large, and thereby the second region 6b may be provided with higher rigidity than the first region 6a and the third region 6c.

  Although not particularly illustrated, the reinforcing cord provided in the second region 6b is made of a material having higher rigidity than the reinforcing cord provided in the first region 6a and the third region 6c, and the second region 6b is formed in the first region. 6a and the third region 6c may be provided with higher rigidity.

  The first region 6a and the third region 6c may be provided with the same rigidity, or the third region 6c may be provided with higher rigidity than the first region 6a, but compared with the first region 6a. By providing the third region 6c with high rigidity, local buckling deformation that occurs in the vicinity of the shoulder main groove 8 during cornering traveling can be suppressed.

  In order to provide the third region 6c with higher rigidity than the first region 6a, when the belt reinforcing layer 6 is formed by spirally winding one or more cords arranged around the tire axis. The feed pitch in the tire width direction in the third region 6c is made smaller than that in the first region 6a to increase the number of ends, or as shown in FIG. 3, the first region 6a to the second region 6b. The belt is reinforced by providing a topping anti-6-1 for the first layer having a width according to the width and a topping anti-6-2 for the second layer having a width according to the widths of the second region 6b and the third region 6c. When the layer 6 is formed, it can be realized by setting the number of ends of the second layer topping anti-6-2 larger than that of the first layer anti-topping anti-6-1.

  In the pneumatic tire of the present embodiment as described above, the belt reinforcing layer 6 laminated on the outer peripheral side of the belt layer 5 has a high second region 6b provided from the shoulder main groove 8 to the intermediate land portion 11. The first region 6a and the third region 6c, which are provided with rigidity and located on both sides in the tire width direction of the second region 6b, are provided with lower rigidity than the second region 6b, and thus are most susceptible to buckling deformation. The rigidity is set to be high from the shoulder main groove 8 to the intermediate land portion 11, and a decrease in steering stability due to buckling deformation during cornering traveling can be suppressed.

  In addition, since the rigidity distribution of the belt layer 5 and the belt reinforcing layer 6 decreases stepwise as they move away from the second region 6b in the tire width direction, the strain concentration is alleviated and deterioration of rolling resistance is suppressed. be able to.

  The belt reinforcing layer 6 may be provided on both sides in the tire width direction or only on one side in the tire width direction. When the belt reinforcing layer 6 is provided only on one side in the tire width direction, buckling deformation is likely to occur in the vicinity of the shoulder main groove 8 located on the outer side during turning. It is preferable to use a tire in which the direction of rotation of the tire is specified so that one side in the tire width direction provided with is positioned outside the vehicle.

  Moreover, although this embodiment demonstrated the case where the tire width direction inner side edge part of the 1st area | region 6a of the belt reinforcement layer 6 was terminated in the middle of the intermediate land part 11, this invention is limited to this. Instead, it may extend beyond the center main groove 9 to the center land portion 12 facing the intermediate land portion 11 and the center main groove 9 without terminating at the intermediate land portion 11.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples.

  Tires (215 / 45R17) of Examples 1 to 3 and Comparative Examples 1 to 3 were manufactured as trials. Each of these prototype tires has the same tire internal structure other than the basic tread pattern and the belt reinforcing layer 6, and as shown in Table 1, the proportion (density) of the reinforcing cord per unit area is defined as the first region 6a, The second region 6b and the third region 6c are changed and manufactured. In Table 1, the density of the reinforcing cord of Comparative Example 1 is expressed as an index with the value 100, and the larger the number, the higher the density of the reinforcing cord and the higher the rigidity.

  Specifically, in the first to third embodiments, the second region 6b of the belt reinforcing layer 6 is set to have a higher density of reinforcing cords and higher rigidity than the first region 6a and the third region 6c. 1, the density of the reinforcing cord in the second region 6b is set to be twice that of the first region 6a and the third region 6c. In Example 2, the density of the reinforcing cord in the second region 6b is set to the first region 6a. And 1.5 times the third area 6c. In Example 3, the density of the reinforcing cord in the second region 6b is set to twice that of the first region 6a, and the density of the reinforcing cord in the third region 6c is 1.5 times that of the first region 6a. Is set.

  In Comparative Example 1, the density of the reinforcing cords in the first region 6a, the second region 6b, and the third region 6c is set to be constant, and the belt reinforcing layer 6 is set to have the same rigidity. In Comparative Example 2, the third region 6c is set to be more rigid than the first region 6a and the second region 6b, and in Comparative Example 3, the first region 6a is changed to the second region 6b and the third region 6c. Compared to high rigidity.

  About each pneumatic tire of Examples 1-3 and Comparative Examples 1-3, cornering power (steering stability) and rolling resistance performance were evaluated. The evaluation method is as follows.

-Cornering power: Using a drum tester having a diameter of 2500 mm, the cornering force generated in the test tire was measured to determine the cornering power at a slip angle of 5 °. Index evaluation is performed with the result of Comparative Example 1 being 100, and the larger the value, the greater the cornering power and the better the steering stability performance.

-Rolling resistance: The rolling resistance was measured with a rolling resistance tester to determine the rolling resistance coefficient. Index evaluation is made with the result of Comparative Example 1 being 100, and the smaller the value, the smaller the rolling resistance and the better the fuel efficiency.

  The results are as shown in Table 1. In Comparative Example 2 in which the third region 6c is set to be highly rigid with respect to Comparative Example 1, the cornering power is improved and the steering stability is improved, but the rolling resistance is increased. Low fuel consumption performance deteriorated. Further, in Comparative Example 3 in which the first region 6a is set to be highly rigid with respect to Comparative Example 1, the cornering power is reduced, the steering stability is deteriorated, the rolling resistance is increased, and the fuel efficiency performance is also deteriorated.

  On the other hand, in Examples 1 to 3 in which the second region 6b is set to be highly rigid with respect to the comparative example 1, the steering stability is improved without increasing the rolling resistance.

In particular, in Example 3 in which the third region 6c is set to be more rigid than the first region 6a in the range where the rigidity is lower than that of the second region 6b in addition to the second region 6b, the cornering power is higher than that of Examples 1 and 2. Greatly improved.

DESCRIPTION OF SYMBOLS 1 ... Bead part 2 ... Side wall part 3 ... Carcass 4 ... Tread part 5 ... Belt layer 6 ... Belt reinforcement layer 7 ... Tread rubber layer 8 ... Shoulder main groove 9 ... Center main groove 10 ... Shoulder land part 11 ... Middle land part 11a ... Inner end 11b ... Outer end 12 ... Center land

Claims (6)

In a pneumatic tire comprising a belt layer, a belt reinforcing layer laminated on the outer peripheral side of the belt layer, and a tread rubber portion disposed on the outer peripheral side of the belt reinforcing layer,
The tread rubber portion includes a shoulder main groove, a center main groove located on the inner side in the tire width direction from the shoulder main groove, a shoulder land portion formed on the outer side in the tire width direction of the shoulder main groove, and the shoulder main groove. And an intermediate land section defined between the center main groove and
The belt reinforcing layer includes: a first region provided in the intermediate land portion; a second region extending from an outer side in the tire width direction of the first region to an outer end portion in the tire width direction of the intermediate land portion; A third region extending from the groove to the shoulder land,
It said second region, said first region and rigidity than the third region is rather high,
The pneumatic tire according to claim 1, wherein the belt reinforcing layer is provided on the vehicle outer side from the tire center line . The pneumatic tire according to claim 1, characterized in that the rotational direction is specified.   The pneumatic tire according to claim 1 or 2, wherein the first region terminates in the intermediate land portion.   The pneumatic tire according to any one of claims 1 to 3, wherein the third region terminates on the inner side in the tire width direction from the ground contact end.   The pneumatic tire according to claim 1, wherein the third region has higher rigidity than the first region.   The first region terminates at a position that is 30% or more of the total width of the intermediate land portion away from the inner end of the intermediate land portion in the tire width direction, and the second region has a width that is equal to the total width of the intermediate region. It is set to 30% or more and 50% or less, The 3rd field ends at the position of 50% or less of the full width of the shoulder land part from the tire width direction inner side end part of the shoulder land part. The pneumatic tire according to any one of 1 to 5.

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