JP4901144B2 - Pneumatic tire - Google Patents

Description

    The present invention relates to a pneumatic tire in which a wide and narrow reinforcing layer for reinforcing a belt layer is disposed in a tread portion.

As conventional pneumatic tires, for example, those described in Patent Document 1 below are known.
JP 9-66705 A

  This includes a belt layer composed of two belt plies in which a non-stretchable reinforcing cord inclined in the opposite direction to the tire equator S is embedded in the tread portion, and the belt layer on the radially outer side of the belt layer. A wide reinforcing layer composed of one wide reinforcing ply arranged so as to cover the entire width of the belt, and one narrow reinforcing ply arranged so as to overlap both ends of the belt layer in the radial direction outside the wide reinforcing layer. A pneumatic tire provided with a pair of narrow reinforcing layers.

  In this pneumatic tire, both the wide reinforcing ply and the narrow reinforcing ply are wound in a spiral shape while stripping a rubber coating with a plurality of reinforcing elements made of organic fiber cords arranged side by side. As a result, while satisfying high speed durability and steering stability sufficiently, road noise (pneumatic tires on the road pick up irregularities on the road surface and the vibrations are transmitted to the air in the passenger compartment. The noise generated due to the vibration is greatly reduced.

    Here, in recent years, with the improvement in performance of passenger cars, further comfortability in the passenger compartment has been demanded, and attention is paid to air column resonance in the tire interior in addition to the road noise. It has become like this. However, the pneumatic tire described in Patent Document 1 described above could hardly be expected to reduce the air column resonance in the tire inner chamber as described above. Here, the air column resonance in the tire inner chamber means that random vibration transmitted from the road surface to the pneumatic tire vibrates the air in the tire inner chamber formed between the rim and the pneumatic tire, A large resonance sound is generated near the air column resonance frequency in the tire inner chamber.

    For this reason, the present inventor has intensively studied whether or not the above-described air column resonance can be suppressed without substantially changing or reducing the structure and performance of the pneumatic tire, and the out-of-plane bending rigidity at the tread central portion is the tread. If the out-of-plane bending stiffness at the end is considerably smaller and the center of the tread is deformed significantly out of plane than the tread end in the ground contact area during rolling, the above-mentioned air column resonance is effectively applied. It was found that it can be suppressed.

The present invention has been made on the basis of the above-described knowledge, and a belt comprising at least two belt plies in which a non-stretchable reinforcing cord inclined in a reverse direction with respect to the tire equator S is embedded in a tread portion. A wide reinforcing layer composed of at least one wide reinforcing ply, and both ends of the belt layer in the width direction on the outer side in the radial direction of the wide reinforcing layer. is arranged so as to overlap with parts, e Bei and a pair of narrow reinforcing layer comprising at least one narrow reinforcement ply, the pre-Symbol wide reinforcement ply, and rubber coatings side by side several reinforcing elements consisting of nylon fiber cord strip And at least one narrow reinforcing ply is made of an organic fiber cord. A pneumatic tire which is constituted by winding a strip of rubberized coated side by side several strong element helically while contacting the side end each other, the pair of narrow reinforcing layer of two narrow reinforcing plies each A narrow reinforcing ply arranged radially inward is provided with a gap having the same width as the gap K between the strips constituting the wide reinforcing ply and the same strip as the strip constituting the wide reinforcing ply. A narrow reinforcing ply arranged on the outer side in the radial direction is wound with a nylon fiber cord strip spirally with the side ends contacting each other. It is configured by turning .

  In the present invention, the wide reinforcing ply covering the belt layer with the full width is configured by winding a plurality of reinforcing elements side by side and rubber-coating a strip uniformly with a predetermined gap K between them. The winding is rougher than the conventional wide reinforcing ply made by winding the strip with the side ends in contact with each other, and the Young's modulus of the reinforcing element embedded inside is relatively low (low elastic modulus). (Ii) Nylon fiber cords, the wide reinforcing layer has a reduced out-of-plane bending rigidity over the entire range.

  On the other hand, among the narrow reinforcing plies arranged so as to overlap the both ends in the width direction of the belt layer on the outer side in the radial direction of the wide reinforcing layer, at least one narrow reinforcing ply has several reinforcing elements made of organic fiber cords. Since the strips coated side by side and coated with rubber are spirally wound with the side edges contacting each other, the winding becomes denser than the wide reinforcing ply, and the out-of-plane bending rigidity of the narrow reinforcing layer is wide reinforcing. The value is higher than the layer. As a result, the out-of-plane bending rigidity of the region where the narrow reinforcing layer is disposed (wide and located at both ends of the tread in the region where the narrow reinforcing layer overlaps) is a composite value of both reinforcing layers, This value is considerably higher than the out-of-plane bending rigidity of the region where only the wide reinforcing layer between the narrow reinforcing layers is arranged (central portion of the tread).

As a result, when the pneumatic tire is loaded and rolled, the center portion of the tread is considerably deformed out of plane in the ground contact area compared to both ends of the tread, and as a result, the deformation mode of the pneumatic tire is changed to the conventional pneumatic tire. The air column resonance described above is effectively suppressed due to a different form from the tire. In addition, at this time, since the narrow reinforcing layer is configured as described above, the circumferential rigidity is maintained at a high value, thereby strongly increasing the diameter growth of the tread edge during high-speed running of the pneumatic tire. Therefore, high speed durability and steering stability can be maintained at high values . Et al is, a narrow reinforcement ply disposed radially inward and a wide width reinforcing ply, it is possible to collectively mold without changing the winding pitch by the same strip, molding operation is facilitated, work efficiency Will also improve.

Hereinafter, an example of a pneumatic tire in which wide and narrow reinforcing layers that reinforce the belt layer are disposed in the tread portion will be described with reference to the drawings.
1 and 2, reference numeral 11 denotes a pneumatic radial tire. The pneumatic tire 11 includes a pair of bead portions 13 each having a bead core 12 embedded therein, and side surfaces extending from the bead portions 13 toward the outside in a substantially radial direction. A wall portion 14 and a substantially cylindrical tread portion 15 that connects the radially outer ends of the sidewall portions 14 are provided. On the other hand, 16 is a rim mounted on a passenger car, and the pneumatic tire 11 is mounted on the rim 16 with the bead portion 13 seated on the bead seat portion 17, so that the rim 16 and the rim 16 are inflated. A sealed tire inner chamber 18 filled with an internal pressure is formed between the tire 11 and the tire 11. The pneumatic tire 11 and the rim 16 described above constitute a tire assembly 19 as a whole.

  The pneumatic tire 11 has a carcass layer 20 that extends between the bead cores 12 in a toroidal shape and reinforces the sidewall portions 14 and the tread portions 15. Both ends of the carcass layer 20 in the width direction of the bead core 12 It is turned around from the axially inner side to the axially outer side. The carcass layer 20 is composed of at least one, in this case, one carcass ply 21, and the carcass ply 21 is composed of organic fibers such as aromatic polyamide and steel substantially extending in the radial direction (meridian direction). A large number of parallel reinforcing cords 22 are embedded.

  23 is a belt layer arranged on the radially outer side of the carcass layer 20, and this belt layer 23 has at least two belt plies, in this case, two belt plies 24, 25 in this order toward the radially outer side. It is configured by stacking. Here, in each belt ply 24, 25, a large number of mutually parallel non-stretchable reinforcing cords 26, 27 are embedded, and these reinforcing cords 26, 27 are stranded wires or monofilaments of steel, aromatic polyamide or the like. It is composed of The reinforcement cords 26 and 27 in the belt plies 24 and 25 are inclined with respect to the tire equator S within a range of 10 to 30 degrees, and at least two belt plies are inclined in the opposite direction with respect to the tire equator S. And cross each other.

  31 is a tread made of rubber disposed radially outward of the carcass layer 20 and the belt layer 23. The outer surface (tread surface) of the tread 31 is continuously continuous in the circumferential direction in order to improve drainage performance. A plurality of extending main grooves 32, here, four main grooves 32 are formed. In addition, a large number of lateral grooves extending in the width direction or oblique direction may be formed on the outer surface of the tread 31.

  35 is disposed adjacent to the outer side of the belt layer 23 in the radial direction so as to cover the entire width of the belt layer 23. Here, the belt layer 23 is slightly wider than the belt layer 23, and both end portions in the width direction protrude outward from the belt layer 23 in the width direction. The wide reinforcing layer is generally called a cap layer, and the wide reinforcing layer 35 is composed of at least one (here, one) wide reinforcing ply 36. Here, the wide reinforcing ply 36 has a predetermined width K between a strip 38 having a constant width and a rubber coating in which several reinforcing elements 37 made of nylon fiber cord, for example, nylon 66 fiber cord and nylon 46 fiber cord are arranged side by side. It is configured by winding uniformly in a spiral manner while being provided.

  As described above, when the wide reinforcing ply 36 is formed by winding the strip 38 in which the reinforcing element 37 is embedded uniformly in a spiral shape while providing the gap K, the wide reinforcing ply 36 is formed inside the wide reinforcing ply 36. As a result, the reinforcing element 37 extending substantially parallel to the tire equator S is embedded, and as a result, the tread portion 15 is restrained from growing greatly in the radial direction due to centrifugal force during high-speed running. Can maintain tire handling stability and high-speed durability. However, since the gap K is provided between the adjacent strips 38, the winding becomes rougher than when the strips 38 are wound while the side ends are in contact with each other, and the reinforcing element 37 embedded therein has a Young's modulus. Since the nylon fiber cord is relatively low (low elastic modulus), the out-of-plane bending rigidity of the wide reinforcing layer 35 is lowered in the entire range as compared with the conventional cap layer.

  In addition, a pair of narrow reinforcing layers 41, usually called layer layers, are provided outside the wide reinforcing layer 35 in the radial direction, and these narrow reinforcing layers 41 are overlapped with both ends of the belt layer 23 in the width direction. The belt layer 23 is disposed so as to straddle the width direction outer end of the belt layer 23 and the width direction outer end of the wide reinforcing layer 35 substantially overlaps the width direction outer end. Here, the narrow-width reinforcing layer 41 is composed of at least one (here, one) narrow-width reinforcing ply 42, but at least one of the narrow-width reinforcing plies 42, here, the narrow-width reinforcing ply 42. Since the reinforcing layer 41 is composed of one narrow reinforcing ply 42, the narrow reinforcing ply 42 is formed by arranging a plurality of reinforcing elements 43 made of organic fiber cords and rubber-coated strips 44 at the side ends 44a. It is configured by winding in a spiral while making contact. As a result, the winding of the narrow reinforcing ply 42 is denser than that of the wide reinforcing ply 36, and the out-of-plane bending rigidity of the narrow reinforcing layer 41 is higher than that of the wide reinforcing layer 35.

  As a result, the out-of-plane bending rigidity of the region where the narrow-width reinforcing layer 41 is disposed (located at both ends of the tread in the region where the wide-width and narrow-width reinforcing layers 35 and 41 are overlapped) is the both reinforcing layers 35 and 41. Is a value that is considerably higher than the out-of-plane bending rigidity of the region (central portion of the tread) where only the wide reinforcing layer 35 between the narrow reinforcing layers 41 is disposed. As a result, when the pneumatic tire 11 is loaded and rolled, the center portion of the tread is considerably deformed out of the plane in comparison with the both ends of the tread in the ground contact region. As a result, the deformation mode of the pneumatic tire 11 is the conventional one. The air column resonance is effectively suppressed due to a different form from the pneumatic tire. In addition, at this time, since the narrow reinforcing layer 41 is configured as described above, the circumferential rigidity is maintained at a high value, thereby increasing the diameter growth of the tread edge during the high-speed running of the pneumatic tire 11. It can be strongly suppressed, and high speed durability and steering stability can be maintained at high values.

  Here, when the width of the strip 38 is W, the predetermined gap K in the wide reinforcing layer 35 is preferably in the range of 1/3 to 1 times the width W. The reason is that when the gap K is less than 1/3 times the width W, the out-of-plane bending rigidity of the wide reinforcing layer 35 is not sufficiently reduced. As a result, the out-of-plane bending between the both ends of the tread and the center of the tread is not achieved. This is because a sufficient difference in rigidity cannot be provided. On the other hand, if it exceeds 1 time, it is a basic function of the wide reinforcing layer 35, but the effect cannot be sufficiently exhibited.

  Further, the Young's modulus (modulus) of the reinforcing element 43 in the narrow reinforcing ply 42 formed by spirally winding the strip 44 with the side ends 44 a in contact with each other is the reinforcing element in the wide reinforcing ply 36. The Young's modulus is preferably larger than 37. The reason is that, in this way, even if the narrow reinforcing layer 41 is constituted by a single narrow reinforcing ply 42, a sufficient difference is provided in the out-of-plane bending rigidity between the tread ends and the tread central portion. This is because air column resonance can be effectively suppressed.

  Here, as the reinforcing element 43 having a Young's modulus larger than that of the reinforcing element 37 made of a nylon fiber cord, for example, a polyethylene naphthalate (polyethylene-2,6-naphthalate) fiber cord, or an aromatic polyamide fiber cord and nylon A composite organic fiber cord twisted by simultaneously spinning the fiber cord can be mentioned. If the organic fiber cord as described above is used as the reinforcing element 43, the reinforcing element 43 extends in the longitudinal direction to some extent at the time of vulcanization, so that the vulcanization molding operation can be facilitated.

FIG. 3 is a diagram showing Embodiment 1 of the present invention. In this embodiment, a pair of narrow reinforcing layers 48 are each composed of two narrow reinforcing plies 49 and 50 laminated in the radial direction, and the reinforcing elements 51 are provided in any of the narrow reinforcing plies 49 and 50. , 52 is made of a nylon fiber cord. In this way, the out-of-plane bending rigidity at both ends of the tread can be strongly increased, and both the wide and narrow reinforcing layers 35 and 48 can be formed with the same strips 38 and 53. Work becomes easy and work efficiency improves.

  Here, the narrow reinforcing ply 49 arranged radially inward is provided with a gap M having the same width as the gap K between the strips 38 constituting the wide reinforcing ply 36 with the nylon fiber cord strip 53 interposed therebetween. A narrow reinforcing ply 50, which is configured by winding uniformly in a spiral shape, on the other hand, is wound spirally with a nylon fiber cord strip 53 in contact with the side ends 53a. It is composed by doing.

In this way, the wide reinforcing ply 36 and the narrow reinforcing ply 49 arranged radially inward can be collectively formed without changing the winding pitch by the same strips 38 and 53, so that the forming operation And the work efficiency is improved .

Next, test examples will be described. In this test, a nylon fiber cord strip was conventionally provided with a wide and narrow reinforcing layer composed of a single wide and narrow reinforcing ply formed by spirally winding the side ends in contact with each other. It consists of a single wide and narrow reinforcing ply constructed by winding the tire 1 and a nylon fiber cord strip together in a spiral manner with a gap K of 1/3 of the strip width W between them. wide, a comparison tire 1 having a narrow reinforcing layer and constituted by uniformly wound spirally while providing a clearance K 1/3 of the strip width W between the strips of nylon fiber cord 1 A wide reinforcing layer composed of a single wide reinforcing ply, and an inner narrow width formed by winding a strip of nylon fiber cord uniformly in a spiral manner with a gap M of 1/3 of the strip width W interposed therebetween Reinforced plastic If, exemplary tire having a narrow reinforcing layer consisting of two narrow reinforcing ply between the outer narrow reinforcing ply is constituted by winding a strip of nylon fiber cord spirally while contacting the side edge to each other 1 was prepared.

Here, the size of each tire is 235 / 50R18, and in each tire, the width of the belt layer is 200 mm, the width of the wide reinforcing ply is 215 mm, and the width of the strip constituting the wide and narrow reinforcing ply Both were 6mm. Also, slave writer Oite the tire 1, the width of the narrow reinforcement ply 40 mm, the width of the inner narrow reinforcement ply in the narrow reinforcement ply and exemplary tire 1 in Comparative tire 1 are both 40 mm, in the exemplary tire 1 The width of the outer narrow reinforcement ply was 30 mm. Moreover, conventional tires 1, comparative tires 1, Oite the embodiment tire 1, (inner) widthwise outer end of the narrow reinforcement ply projects only outside in the width direction 5mm from the widthwise outer end of the wide reinforcing ply also, In the implementation tire 1 , the outer end in the width direction of the outer narrow reinforcing ply protruded outward in the width direction by 0 mm from the outer end in the width direction of the inner narrow reinforcing ply.

Next, after filling the tire interior of each of the tires with 230 kPa of internal pressure, it is mounted on a domestic passenger car and runs on the road noise evaluation road test course at 60 km / h, and is collected at the center of the backrest of the driver's seat. A sound microphone was attached, and the total sound pressure (decibel) at an air column resonance frequency of 200 to 250 Hz of the tire was measured. When index displays the result on the conventional tire 1 as 100, but in Comparative tire 1 is changed was 100 without the implementation tire 1 air column resonance sound was reduced to 90.

In addition, after filling each tire with an internal pressure of 155 kPa, the speed was increased in steps of 10 km every 30 minutes until a failure occurred from 230 km / h on the drum while applying a load of 9.4 kN. The speed was measured. When the result is shown as an index with the conventional tire 1 as 100, the high speed durability improved to an index of 105 in the implementation tire 1 , but decreased to 95 in the comparative tire 1.

  The present invention can be applied to the industrial field of pneumatic tires in which wide and narrow reinforcing layers that reinforce the belt layer are disposed in the tread portion.

It is meridian sectional drawing which shows an example of a pneumatic tire . It is a partially broken plan view of the tread portion. It is a partially broken top view of the narrow reinforcement layer vicinity which shows Embodiment 1 of this invention.

11 ... Pneumatic tire 15 ... Tread part
23 ... Belt layer 24, 25 ... Belt ply
26, 27 ... Reinforcement cord 35 ... Wide reinforcement layer
36… Wide reinforcing ply 37… Reinforcing element
38 ... Strip 41 ... Narrow reinforcing layer
42 ... Narrow reinforcing ply 44a ... Side end
43… Reinforcing element 44… Strip

Claims (1)

A belt layer composed of at least two belt plies in which a non-stretchable reinforcement cord inclined in the opposite direction with respect to the tire equator S is embedded in the tread portion, and the belt layer at a full width outside the belt layer in the radial direction. A wide reinforcing layer composed of at least one wide reinforcing ply, and arranged to overlap both ends in the width direction of the belt layer on the outer side in the radial direction of the wide reinforcing layer, and from at least one narrow reinforcing ply Bei example a pair of narrow reinforcing layer made, before Symbol a wide reinforcing ply, uniformly wound spirally while providing a predetermined gap K between several side by side strips and rubber coated reinforcing elements consisting of nylon fiber cord A strip formed by rotating a rubber coating with at least one narrow reinforcing ply and a plurality of reinforcing elements made of organic fiber cords arranged side by side. A pneumatic tire configured by winding spirally while contacting the end with each other, thereby constituting a pair of narrow reinforcing layer of two narrow reinforcing plies respectively, are disposed radially inward The narrow reinforcing ply is wound uniformly in a spiral manner with a gap M having the same width as the gap K between the strips forming the wide reinforcing ply interposed between the same strips forming the wide reinforcing plies. On the other hand, the narrow reinforcing ply arranged on the outer side in the radial direction is formed by winding a strip of nylon fiber cord in a spiral shape with the side ends contacting each other. And pneumatic tires.

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