JP6092061B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  A general pneumatic tire includes a belt reinforcing layer on the belt layer. The belt reinforcing layer is formed by spirally winding a long rubber member in which a cord is embedded on the belt layer.

  In order to improve the steering stability of the tire, it is effective to increase the winding tension of the long rubber member and increase the rigidity of the belt reinforcing layer. However, if this is done, the tire's sensitivity to road surface unevenness increases, and the ride comfort of the vehicle deteriorates.

  Therefore, as described in Patent Document 1, it is also conceivable to reduce the winding tension of the belt reinforcing layer in the tire center portion having a small influence on the steering stability. However, that alone does not improve the ride comfort of the vehicle.

JP 2007-137199 A

  The problem to be solved by the present invention is to provide a pneumatic tire having high steering stability and good ride comfort of a vehicle equipped with the same.

  The pneumatic tire of the embodiment is a pneumatic tire in which a belt reinforcing layer is formed by winding a cord on the belt layer at an angle with respect to the tire circumferential direction, and the pneumatic tire in the center region in the tire width direction The angle is larger than the angle in the shoulder region on both sides of the center region, and the winding tension in the shoulder region of the cord is larger than the winding tension in the center region.

  The pneumatic tire according to the embodiment has high steering stability, and the riding comfort of a vehicle equipped with the pneumatic tire is good.

Sectional drawing of the tire of embodiment. The figure which shows the tread pattern of the tire of embodiment. The perspective view of the long rubber member of an embodiment. The figure explaining the winding angle of the long rubber member for belt reinforcement layers.

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

(1) Structure of Pneumatic Tire 1 of Embodiment As shown in FIG. 1, the pneumatic tire 1 of the embodiment has a bead portion 2 including a bead core 20 and a bead filler 21, and a tire width that wraps the bead portion 2. The carcass 3 is folded back from the inner side in the direction. A belt layer 4, a belt reinforcing layer 5, and a tread 6 are laminated in this order on the outer side in the tire radial direction of the carcass 3. The tread pattern of the tread 6 is not limited, but there is, for example, one having four straight main grooves 60 as shown in FIG. An inner liner 30 is disposed inside the carcass 3, and a sidewall 7 is disposed outside the axial direction.

  The pneumatic tire 1 is divided into an inner shoulder region IS, an inner center region IC, an outer center region OC, and an outer shoulder region OS in order from the inner side in the width direction. Here, the inner side is the direction toward the vehicle when the tire 1 is mounted on the vehicle, and the outer side is the direction toward the outer side of the vehicle. Further, the shoulder region is a region outside the outermost main groove in the tire width direction when the tread has three or more linear main grooves. The outermost main groove in the tire width direction has a constant width, and it is determined for each tire which position within the width is the shoulder region. For example, it may be the outermost position in the outermost main groove in the tire width direction, or may be the width direction center in the main groove. When there are two or less linear main grooves or when there are no linear main grooves, the tire is in the region from the ground contact end of the tire 1 to the inner position by a length of 10 to 20% of the ground contact width. This is an area determined for each. In particular, a region from the ground contact end of the tire 1 to a position inside by a length of 15% of the ground contact width is desirable. Here, the contact end is the end in the tire width direction of the tread surface where the tire comes into contact with the road surface when a standard load (a load of 75% of the maximum load specified by JATMA) is applied. The contact width is the width of the tread surface that comes into contact with the road surface when a standard load is applied to the tire. The center region is a region sandwiched between the inner and outer shoulder regions. The boundary between the inner side and the outer side of the center region is a center line CL of the ground contact width.

  The belt reinforcing layer 5 is formed by winding a long rubber member 50 in a spiral shape. As shown in FIG. 3, the long rubber member 50 is formed by covering a predetermined number of cords 51 arranged in parallel with a rubber 52. The cord 51 includes steel and twisted organic fibers, and any of them may be used. The extending directions of the long rubber member 50 and the cord 51 are the same.

  As shown in FIG. 4, the angle of the long rubber member 50 with respect to the tire circumferential direction (also the angle of the cord 51 with respect to the tire circumferential direction) differs between the shoulder region and the center region. The angle of the center region is larger than the angle of the shoulder region. Although the specific value of the angle is not limited, for example, the angle of the center region is in the range of 2 ° to 5 °, and the angle of the shoulder region is in the range of more than 0 ° and 3 ° or less. The difference in angle between the center region and the shoulder region is preferably 0.5 ° or more, and more preferably 1 ° or more. FIG. 4 is a simplified diagram, and the number of windings of the long rubber member 50 does not necessarily match the number described in FIG.

  The long rubber member 50 includes a long rubber member 50a for the center region and a long rubber member 50b for the shoulder region. The long rubber member 50a for the center region is thicker than the long rubber member 50b for the shoulder region. Thereby, even if the long rubber member 50a for the center region is wound at a larger angle with respect to the tire circumferential direction than the long rubber member 50b for the shoulder region, the long rubber members 50a adjacent to each other in the tire axial direction are There is no gap between them.

  The number of the cords 51 embedded in one long rubber member 50 is not limited. However, the density of the cord 51 in the width direction of the long rubber member 50 is the same for the long rubber member 50a for the center region and the long rubber member 50b for the shoulder region, and as a result, the cord 51 has a large thickness for the center region. It is desirable that more cords 51 are embedded in the long rubber member 50a than in the thin long rubber member 50b for the shoulder region. When the long rubber member 50a for the center region and the long rubber member 50b for the shoulder region are wound adjacent to each other in the tire width direction, the number of ends (the width of the belt reinforcing layer 5 is 1 inch (25.4 mm)). It is desirable that the number of the cords 51 be determined so that the number of the cords 51) is constant in the tire width direction from the inside to the outside. In that case, the number of ends of the belt reinforcing layer 5 is constant in the tire width direction from the inside to the outside.

Further, the tension in the winding direction (extension direction) of the cord 51 in the shoulder region in the tire width direction is larger than the same tension in the center region. Strictly speaking, the boundary between the large tension portion and the small tension portion in the tire width direction is the same position as the boundary between the center region and the shoulder region or a position closer to the tire center than the boundary. In particular, it is desirable that the center side position is a distance of 10 to 25% of the width of the center region from the boundary between the center region and the shoulder region on both sides in the tire width direction. The value of the tension of the cord 51 is not limited to, for example 5~10N / mm ² at the center side, it is 10 to 30 N / mm ² approximately at shoulder side.

(2) Manufacturing method of pneumatic tire 1 of embodiment An example of the manufacturing method of the pneumatic tire 1 of the above structures is demonstrated. First, members constituting the tire 1 such as the bead core 20 and the long rubber member 50 for the belt reinforcing layer 5 are manufactured by a well-known method.

  Next, these members are combined to produce a green tire. Specifically, first, components inside the tire, such as the carcass 3 and the inner liner 30, are laminated on a drum and laminated into a cylindrical shape. The cylindrical molded body is set with the bead portion 2 and turned up, and the side walls are attached to complete a so-called green case.

  On the other hand, the belt layer 4, the belt reinforcing layer 5, and the tread 6 are laminated in this order on another drum.

  Here, the belt reinforcing layer 5 is formed as follows. First, the drum to which the belt layer 4 is attached is rotated in the circumferential direction. Next, the long rubber member 50 for the belt reinforcing layer 5 is supplied and pasted to the belt layer 4 rotating together with the drum through a supply device having a known structure. At that time, since the drum is continuously fed in the axial direction (tire width direction) while rotating in the circumferential direction, the long rubber member 50 for the belt reinforcing layer 5 is spirally wound on the belt layer 4. To go.

  Specifically, as the drum starts to rotate, the long rubber member 50b for the shoulder region is supplied from the supply device and is wound around a portion that becomes the inner shoulder region IS. When the winding is finished, the rotation of the drum and the supply of the long rubber member 50b for the shoulder region are stopped. And the long rubber member 50 of a supply apparatus is replaced | exchanged for the long rubber member 50a for center areas. Thereafter, when the drum starts to rotate again, the long rubber member 50a for the center region is supplied from the supply device, and is wound around the portions to be the center regions IC and OC. The speed of feeding the drum in the axial direction during winding is faster than the speed of feeding the drum in the axial direction when winding the long rubber member 50b around the inner shoulder region IS. When the winding is finished, the rotation of the drum and the supply of the long rubber member 50a for the center region are stopped. And the long rubber member 50 of a supply apparatus is replaced | exchanged for the long rubber member 50b for shoulder regions. Thereafter, when the drum starts to rotate again, the long rubber member 50b for the shoulder region is supplied from the supply device, and is wound around the portion that becomes the outer shoulder region OS. The speed of feeding the drum in the axial direction during winding is the same as the speed of feeding the drum in the axial direction when winding the long rubber member 50b around the inner shoulder region IS. When the winding from the inside to the outside is completed, the formation of the belt reinforcing layer 5 is completed. At the time of the above winding, a necessary tension is applied to the cord 51.

  In addition, two supply devices for the long rubber member 50b for the shoulder region and one supply device for the long rubber member 50a for the center region are prepared, the inner shoulder region IS, the center region IC, OC, The shoulder area OS may be wound at the same time.

  Further, two supply devices for the long rubber member 50b for the shoulder region and one supply device for the long rubber member 50a for the center region are prepared, and the inner shoulder region IS, the center region IC, OC, Winding may be performed in the order of the shoulder region OS.

  When the annular laminated body of the belt layer 4, the belt reinforcing layer 5, and the tread 6 is completed, the laminated body is attached to the outer peripheral side of the green case to complete a so-called green tire. Finally, the green tire is vulcanized to complete the pneumatic tire 1.

(3) Effect The tire 1 of this embodiment has high steering stability because the tension of the cord 51 of the long rubber member 50b on the shoulder side is large. More specifically, the steering stability of the tire 1 is affected by the rigidity of the belt reinforcing layer 5 in the tire circumferential direction. In particular, the rigidity on the shoulder side in the tire width direction has a greater influence than the rigidity on the center side. . And the one where rigidity is large has high steering stability. In the case of the tire 1 of the embodiment, since the tension of the cord 51 of the long rubber member 50b on the shoulder side is large, the rigidity of the belt reinforcing layer 5 on the shoulder side in the tire circumferential direction is large. Therefore, the steering stability is high.

  Moreover, since the angle with respect to the tire circumferential direction of the winding of the cord 51 of the long rubber member 50b in the shoulder region is small, the vector in the tire circumferential direction of the winding tension is large. As a result, the rigidity of the belt reinforcing layer 5 in the shoulder region in the tire circumferential direction increases, and the steering stability increases.

  In the region where the winding tension of the cord 51 of the long rubber member 50b is large and the angle with respect to the tire circumferential direction is small, the vector of the winding tension in the tire circumferential direction becomes particularly large. The circumferential rigidity is particularly increased. Therefore, the steering stability of the tire 1 is very high.

  On the other hand, on the center side, since the tension of winding of the cord 51 of the long rubber member 50a is small, the ride comfort of the vehicle equipped with the tire 1 is good. More specifically, the rigidity in the tire circumferential direction of the belt reinforcing layer 5 of the tire 1 influences the ride comfort of the vehicle equipped with the tire 1, and the rigidity in the center side in the tire width direction is particularly in the shoulder side. It has a greater effect than stiffness. And the smaller the rigidity, the better the envelope characteristics, so the ride quality is better. In the case of the tire 1 of the embodiment, since the tension of the winding of the cord 51 of the long rubber member 50a is small on the center side, the rigidity of the belt reinforcing layer 5 on the center side in the tire circumferential direction is small. Therefore, ride comfort is good.

  Moreover, since the angle with respect to the tire circumferential direction of winding of the cord 51 of the long rubber member 50a in the center region is large, the magnitude of the vector in the tire circumferential direction of the winding tension is small. As a result, the rigidity of the belt reinforcing layer 5 in the center region in the tire circumferential direction is reduced, and the ride comfort is improved.

  In the region where the winding tension of the cord 51 of the long rubber member 50a is small and the angle with respect to the tire circumferential direction is large, the size of the vector of the winding tension in the tire circumferential direction is particularly small. The circumferential rigidity is particularly small. Therefore, the ride comfort of the vehicle equipped with the tire 1 is very good.

  When the position where the winding tension of the cord 51 of the long rubber member changes is at a center side by a certain width from the boundary between the center region and the shoulder region, it contributes to improvement in both handling stability and riding comfort. More specifically, the rigidity of a portion having a constant width from the boundary between the center region and the shoulder region affects both the handling stability and the ride comfort. Therefore, it is desirable that the rigidity of this portion is not extremely large or small. When the position at which the winding tension of the cord 51 of the long rubber member changes is on the center side by a certain width from the boundary between the center region and the shoulder region, the cord 51 of the long rubber member 50a is wound around the tire circumferential direction. While the angle is large, a portion having a large tension in the circumferential direction of the wound tire is formed. Then, since the rigidity in the tire circumferential direction of the portion becomes an appropriate size, both steering stability and riding comfort are improved. In particular, from the boundary between the center region and the shoulder region to the position on the center side by a distance of 10 to 25% of the width of the center region, both the steering stability and the ride comfort are easily affected. Therefore, when the position where the tension of winding of the cord 51 of the long rubber member is changed by a distance of 10 to 25% of the width of the center region from the boundary between the center region and the shoulder region, the steering stability Both sex and comfort are improved.

  Further, if the number of ends of the belt reinforcing layer 5 is constant in the tire width direction, the straight running stability and uniformity of the tire 1 are improved.

(4) Example Steering stability and riding comfort were compared by changing the winding angle of the cord 51 of the long rubber member 50 and the tension in the winding direction. The tire used for the test has a size of 195 / 65R15 and four main grooves.

  The cornering force was calculated as an indicator of steering stability. The test for determining the cornering force was carried out using a drum tester having a diameter of 2500 mm. The cornering force at a slip angle of 2 ° was determined. The value in the cornering force column of Table 1 is an index when the cornering force of Comparative Example 1 is 100. The larger the index, the greater the cornering force.

  Riding comfort was evaluated by a sensory test. Specifically, the evaluator got on a real vehicle and got over a protrusion with a width of 20 mm and a height of 10 mm at 60 km / h, and sensory evaluation of the ride comfort at that time was performed. The value in the column of riding comfort in Table 1 is an index when the riding comfort of Comparative Example 1 is 100. The higher the index, the better the ride.

  The test results are shown in Table 1. When the winding angle of the cord 51 of the long rubber member 50 and the tension in the winding direction are changed in the tire width direction as in the above embodiment (in the case of Examples 1 and 2), these are not changed (comparison) The cornering force index is larger than in the case of Example 1. From this, it was confirmed that the steering stability was high. In addition, the index of ride comfort is the same in Examples 1 and 2 and Comparative Example 1. From this, it was confirmed that even if the rigidity of the belt reinforcing layer 5 on the shoulder side is large in the tire circumferential direction, the ride comfort is improved if the rigidity on the center side is small.

  Further, when the tension change point is closer to the center than the angle change point (in the case of Example 2), the cornering force index is larger than when the tension change point is the same as the angle change point (in the case of Example 1). . From this, it was confirmed that the steering stability was high.

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 2 ... Bead, 20 ... Bead core, 21 ... Bead filler, 3 ... Carcass, 30 ... Inner liner, 4 ... Belt layer, 5 ... Belt reinforcement layer, 50 ... Long rubber member, 50a ... Center area | region Long rubber member for 50b ... Long rubber member for shoulder region, 6 ... Tread, 51 ... Cord, 52 ... Rubber, 60 ... Main groove, 7 ... Side wall, CL ... Center line, IC ... Inner center Area, IS ... inner shoulder area, OC ... outer center area, OS ... outer shoulder area

Claims (3)

A pneumatic tire in which a belt reinforcement layer is formed by winding a cord on the belt layer at an angle with respect to the tire circumferential direction,
The angle in the center region in the tire width direction is larger than the angle in the shoulder region on both sides of the center region,
A pneumatic tire in which a winding tension in a shoulder region of the cord is larger than a winding tension in a center region.   2. The pneumatic tire according to claim 1, wherein a position where the winding tension of the cord changes is closer to the center by a distance of 10 to 25% of the width of the center region than a position where the winding angle changes.   The pneumatic tire according to claim 1 or 2, wherein the number of ends of the belt reinforcing layer is constant in the tire width direction.

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