JP2013151184A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which suppresses ply steer with both steering stability and riding comfortability maintained.SOLUTION: In a pneumatic tire T, a carcass layer 5 is disposed between bead cores 4 buried in a pair of right and left beads 3, and both ends of the carcass layer 5 are folded from the inside of the tire to outside around the bead cores 4 so that a bead filler 8 is wrapped around. A belt layer 6 is arranged at the outer circumference side of the carcass layer 5 in a tread 1, and a mounting direction with respect to a vehicle is specified. The belt layer 6 includes a belt cord extending in an arc form, and the arc form belt cord is arranged so as to project toward the outside when mounted to a vehicle, and the height Lof the bead filler 8of the outside when mounted to the vehicle is higher than the height Lof the bead filler 8of the inside when mounted to the vehicle.

Description

  The present invention relates to a pneumatic tire that suppresses price tear while achieving both steering stability and riding comfort.

  In general, a pneumatic tire is required to achieve both high handling stability and riding comfort. However, in order to improve steering stability, it is necessary to increase the tire rigidity, whereas in order to improve riding comfort, it is necessary to reduce the tire rigidity. Therefore, it has been a difficult task to achieve both handling stability and riding comfort.

  On the other hand, in a pneumatic tire in which a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, there is a vehicle flow problem that when the vehicle is moved straight away from the handle, the vehicle bends and flows to one side. As a cause of the vehicle flow, there is a price tear generated when the belt cord of the belt layer is inclined in the tire circumferential direction.

  For this reason, Patent Document 1 proposes a pneumatic tire that suppresses the occurrence of price tear by folding back along the tire equator when the belt cord of the belt layer extends from one end to the other end. Yes. However, in this pneumatic tire, since the belt cord inclination changes discontinuously on the tire equator, there is a problem that the behavior changes abruptly in a transitional state from straight to turning or from turning to straight. In addition, since all belt cords are folded along the equator line, there is a problem that productivity is lowered, and it is impossible to solve the problem of improving both handling stability and riding comfort.

JP 2009-90675 A

  An object of the present invention is to provide a pneumatic tire in which price tear is suppressed while achieving both handling stability and riding comfort.

In the pneumatic tire of the first aspect of the present invention that achieves the above object, a carcass layer is mounted between bead cores embedded in a pair of left and right bead portions, and bead fillers are placed around the bead core at both ends of the carcass layer. In a pneumatic tire having a configuration in which a belt layer is disposed on the outer peripheral side of the carcass layer in a tread portion so as to be wrapped from the inside to the outside of the tire, and the mounting direction with respect to the vehicle is specified, the belt layer is a circle An arc-shaped belt cord is included, the arc-shaped belt cord is arranged so as to protrude outward when the vehicle is mounted, and the height L _{out of the} bead filler on the outer side when the vehicle is mounted is the inner side when the vehicle is mounted. It is characterized by being higher than the height L _in of the bead filler.

The pneumatic tire of the second aspect of the present invention is a tire in which a carcass layer is mounted between bead cores embedded in a pair of left and right bead portions, and both end portions of the carcass layer wrap around bead fillers around the bead core, respectively. In a pneumatic tire that is folded from the inside to the outside and has a configuration in which a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, and the mounting direction with respect to the vehicle is specified, the belt layer extends in an arc shape. A belt cord is included, and the arc-shaped belt cord is arranged so as to protrude outward when the vehicle is mounted, and the hardness H _out measured by JIS K6253 of the bead filler on the outside when the vehicle is mounted is mounted on the vehicle. It is characterized by being higher than the hardness H _in of the inner bead filler.

  In the pneumatic tires of the first and second aspects of the invention, the belt cords extending in an arc shape constituting the belt layer are arranged so as to protrude outward when the vehicle is mounted, and the bead filler on the outer side when the vehicle is mounted It is common that the reinforcing action is larger than the reinforcing action of the inner bead filler when the vehicle is mounted.

  In the pneumatic tires according to the first and second aspects of the present invention, the arc-shaped reinforcing cords in the belt layer are arranged so as to protrude outward when the vehicle is mounted. In this case, since the angle of the belt cord with respect to the tire circumferential direction is reduced and the arrangement density is increased, the in-plane bending rigidity is increased and the steering stability is improved. In addition, the end of the arc belt cord is arranged inside the belt layer when the vehicle is installed, so the angle with respect to the tire circumferential direction is increased and the arrangement density is reduced, so the out-of-plane bending rigidity is reduced and the riding comfort is improved. To do. This is because pneumatic tires are generally attached to the negative camber on the vehicle, so the vehicle inner side, which has a low out-of-plane bending rigidity, contacts the ground when traveling straight, improving ride comfort and the outside of the vehicle with a high in-plane bending rigidity when turning Since the vehicle is grounded and a load is applied thereto, the handling stability is improved. Further, when traveling straight, the inner side of the vehicle is mainly grounded and the price tear component caused by the inclination of the belt cord of the belt layer is reduced, so that the vehicle flow can be suppressed. In addition, since the belt cord is arranged in an arc shape, the inclination angle of the belt cord gradually changes, so that the behavior change in a transitional state from straight traveling to turning or from turning to straight traveling can be moderated. .

In the pneumatic tire according to the first aspect of the present invention, the height L _out of the bead filler on the outer side when the vehicle is mounted is made higher than the height L _in of the inner bead filler when the vehicle is mounted. Since the hardness H _out of the bead filler on the outer side when the vehicle is mounted is higher than the hardness H _in of the inner bead filler when the vehicle is mounted, the pneumatic tire of the first and second inventions In any case, the reinforcing action of the outer bead filler when the vehicle is mounted is larger than the reinforcing action of the inner bead filler when the vehicle is mounted. As a result, the tire rigidity on the inner side when the vehicle is mounted is lowered, and the riding comfort can be further improved. Further, the outer tire rigidity is increased when the vehicle is mounted, and the steering stability during turning can be further improved.

In the pneumatic tire of the first aspect of the present invention, the ratio L _out / L _in of the height L _out and the height L _in of the bead filler is preferably 1.05 to 3.0. By adjusting the bead filler height ratio L _out / L _in to a range of 1.05 to 3.0, the difference in rigidity between the outside and inside when the vehicle is installed is optimized, and the adverse effect on the exercise performance and durability is reduced. Can be suppressed.

In the pneumatic tire according to the second aspect of the present invention, it is preferable that the difference (H _out −H _in ) between the hardness H _out and the hardness H _in of the bead filler is 5 to 50. By setting the difference in hardness of the bead filler (H _out -H _in ) in the range of 5 to 50, the rigidity difference between the outside and the inside when the vehicle is mounted is optimized, and adverse effects on the exercise performance and durability are suppressed. be able to.

  The end of the arc-shaped belt cord is positioned at the inner end of the belt layer when the vehicle is mounted, and the apex outside the arc-shaped belt cord in the tire width direction is positioned at the outer end of the belt layer when mounted on the vehicle. It is preferable.

  It is preferable that an angle θ with respect to the tire circumferential direction of a tangent line of the arcuate belt cord at the inner end of the belt layer when the vehicle is mounted is 50 to 90 °. By making the angle θ within such a range, the ride comfort can be sufficiently improved, and the price tear component can be reduced to suppress the vehicle flow.

  At the inner end of the belt layer when the vehicle is mounted, a tire circumferential distance P between the end of the arc belt cord and the end of the arc belt cord adjacent to the tire circumferential direction is 1.5 to 4.5 mm. Preferably there is. By setting the tire circumferential direction distance P of the arc-shaped belt cord within such a range, it is possible to ensure the belt rigidity at the inner end portion and the outer end portion when the vehicle is mounted and to ensure both driving stability and durability. .

It is sectional drawing of the tire meridian direction which shows an example of embodiment of the pneumatic tire of this invention. It is explanatory drawing which shows typically an example of embodiment of the belt layer of the pneumatic tire of this invention. FIG. 3 is an explanatory diagram schematically showing the arrangement of one belt cord in the belt layer of FIG. 2. It is explanatory drawing which shows typically the other example of embodiment of the belt layer which comprises the pneumatic tire of this invention. It is sectional drawing of the tire meridian direction which shows another example of embodiment of the pneumatic tire of this invention.

  The pneumatic tires according to the first and second aspects of the present invention have an asymmetrical tread pattern in which a mounting direction with respect to a vehicle is specified. In this specification, the vehicle side when the pneumatic tire is mounted on the vehicle is referred to as an inner side when the vehicle is mounted, and the opposite side is referred to as an outer side when the vehicle is mounted. 1 to 5 described below, the symbol IN represents the inside when the vehicle is mounted, and the symbol OUT represents the outside when the vehicle is mounted.

  FIG. 1 is a meridional direction sectional view showing an example of an embodiment of a pneumatic tire according to the first aspect of the present invention.

In FIG. 1, a pneumatic tire T includes a tread portion 1, a sidewall portion 2, and a bead portion 3, and a carcass layer 5 is mounted between a pair of left and right bead cores 4 embedded in the bead portion 3. Are folded from the inside of the tire to the outside so as to wrap the bead filler 8 around the bead core 4. Here, the bead filler 8 is disposed on the outer side in the tire radial direction of the bead core 4 so that the height L _out of the bead filler 8 _{out on} the outer side OUT when the vehicle is mounted is higher than the height L _in of the inner bead filler when the vehicle is mounted. To. A belt layer 6 is disposed over the circumference of the tire on the outer peripheral side of the carcass layer 5 of the tread portion 1. A belt reinforcing layer 9 is disposed on the outer peripheral side of the belt layer 6 so as to wind the reinforcing cord in a spiral shape in the tire circumferential direction.

  In the pneumatic tire of the present invention, at least one belt layer 6 is constituted by a belt cord 7 extending in an arc shape as shown in FIG. 2, and each arc-shaped belt cord 7 is arranged on the outer side OUT when the vehicle is mounted. It is arranged so as to become convex.

  As shown for one cord in FIG. 3, the arc-shaped belt cord 7 has its end portions e and e positioned at the inner end portion 6 i of the belt layer 6 when the vehicle is mounted, and the tire width of the arc-shaped belt cord 7. The arcuate apex a on the outer side in the direction is preferably located at the outer end 6o of the belt layer 6 when the vehicle is mounted. It should be noted that both ends e of the arc belt cord 7 are preferably positioned at the inner end 6i when the belt layer 6 is mounted on the vehicle, but at least one end e is the inner end 6i when the belt layer 6 is mounted on the vehicle. The other end may be located at the circumferential end of the belt layer 6. This is a form allowed for the convenience of molding including the step of winding the belt layer 6.

  In the present invention, the arrangement of all the arc-shaped belt cords 7 constituting the belt layer 6 is convex toward the outer side OUT when the vehicle is mounted, so that the tire circumferential direction R of the belt cord 7 is on the outer side when the belt layer 6 is mounted on the vehicle. As the angle with respect to becomes smaller, the arrangement density becomes higher, so the in-plane bending rigidity becomes higher. Further, since the end portion e of the arc-shaped belt cord 7 is disposed on the inner side of the belt layer 6 when the vehicle is mounted, the angle with respect to the tire circumferential direction is increased and the arrangement density is reduced, so that the out-of-plane bending rigidity is reduced. The pneumatic tire of the present invention is mounted on a negative camber in a vehicle. For this reason, when the vehicle goes straight, the vehicle inside of the pneumatic tire is mainly grounded, and the out-of-plane bending rigidity inside the vehicle is reduced, so that the riding comfort is improved. Further, when the vehicle turns, a load is mainly applied to the outside of the pneumatic tire, and the in-plane bending rigidity on the outside of the vehicle is increased, so that the steering stability is improved.

  Further, in the present invention, since the inside of the vehicle is grounded mainly when the vehicle goes straight, the price tear component due to the inclination of the belt cord of the belt layer is reduced. Since the price tear component is thus suppressed, the vehicle flow can be suppressed. Furthermore, the belt cord is arranged in an arc shape so that the inclination angle of the belt cord changes gradually, so when the vehicle moves from straight running to turning and the load moves from the inside to the outside when a pneumatic tire is installed, or turning When the load is shifted from the outside to the inside when the pneumatic tire is mounted from the vehicle to the straight running, the behavior change in the transient state in the region where the load is applied can be moderated.

  FIG. 4 is an explanatory view schematically showing a belt layer constituting another embodiment of the pneumatic tire of the present invention. The reference numerals are the same as those shown in FIGS.

  4, in the pneumatic tire of the present invention, the angle θ with respect to the tire circumferential direction R of the tangent line of the circular belt cord 7 at the inner end 6i of the belt layer 6 when the vehicle is mounted is preferably 50 ° to 90 °. The angle is preferably 80 ° to 90 °. If the angle θ is less than 50 °, the out-of-plane rigidity on the inner side when the vehicle is mounted becomes high, so that the effect of improving riding comfort cannot be sufficiently obtained. In addition, since the price tear component due to the inclination angle of the belt cord gradually increases, it becomes difficult to suppress the vehicle flow.

  Further, as shown in FIG. 4, the pneumatic tire of the present invention has an arcuate belt cord in which the end e of the arcuate belt cord 7 is adjacent to the tire circumferential direction R at the inner end 6i of the belt layer 6 when the vehicle is mounted. 7 is preferably 1.5 to 4.5 mm, more preferably 2.2 to 2.8 mm. When the distance P is less than 1.5 mm, the density around the apex a of the arc-shaped belt cord 7 on the outer side when the belt layer 6 is mounted on the vehicle becomes excessive, and the rigidity of the belt layer becomes too large. When the distance P exceeds 4.5 mm. The belt rigidity inside the belt layer 6 when the vehicle is mounted becomes too small. In any case, not only the motion performance of the pneumatic tire is deteriorated but also the tire durability is lowered. The arc-shaped belt cords adjacent to each other in the tire circumferential direction are belt cords that overlap each other near the apex of the convex portion of the arc. The distance between the belt cords is the distance in the tire circumferential direction between the center points of the two belt cords.

  The material of the belt cord is not particularly limited, but a steel cord is preferable. By constituting the belt cord with a steel cord, it becomes easy to maintain the arrangement form of the belt cord formed in an arc shape.

In the pneumatic tire of the first aspect of the present invention, as shown in FIG. 1, the bead filler 8 has a height L _out of the bead filler 8 _{out on} the outside OUT when the vehicle is mounted, and the height L _out of the bead filler 8 on the inside when the vehicle is mounted. to be higher than _in. As a result, the height L _{out of the} outer bead filler 8 _out when the vehicle is mounted increases and the outer reinforcing action increases when the vehicle is mounted, and the height L _{in of the} inner bead filler 8 _in decreases when the vehicle is mounted. The inner reinforcing action becomes smaller. For this reason, as described above, the tire rigidity is lowered on the inner side when the vehicle is mounted due to the synergistic effect of arranging the arc belt cord so that the convex portion is on the outer side when the vehicle is mounted and both ends are the outer side when the vehicle is mounted. Riding comfort can be further improved. Further, the tire rigidity is increased on the outside when the vehicle is mounted, and the steering stability during turning can be further improved.

In the first aspect of the present invention, the ratio L _out / L _in between the height L _out and the height L _in of the bead filler is preferably 1.05 to 3.0, more preferably 1.5 to 2.5. . By setting the bead filler height ratio L _out / L _in within such a range, it is possible to optimize the difference in rigidity between the outside and the inside when the vehicle is mounted, and to suppress adverse effects on exercise performance and durability. it can.

In the pneumatic tire of the second aspect of the present invention, the bead filler 8 is configured such that the hardness H _out of the bead filler 8 _{out on} the outer side OUT when the vehicle is mounted is greater than the hardness H _in of the bead filler 8 _{in on} the inner side when the vehicle is mounted. Can do. At this time, as shown in FIG. 5, the height L _out of the bead filler 8 _{out on} the outer side OUT when the vehicle is mounted may be the same as the height L _in of the bead filler 8 on the inner side when the vehicle is mounted. By the hardness H _out of the outer bead filler 8 _out greater than the hardness H _in the inside bead filler, the reinforcing effect of the outside bead filler 8 _out, it can be made larger than the reinforcing effect of the inside bead filler 8 _in . For this reason, due to a synergistic effect with the arrangement of the arc-shaped belt cord described above, the tire rigidity is lowered on the inner side when the vehicle is mounted, and the riding comfort can be further improved. Further, the tire rigidity is increased on the outside when the vehicle is mounted, and the steering stability during turning can be further improved.

In the second aspect of the present invention, the difference between the hardness H _out and the hardness H _in of the bead filler (H _out −H _in ) is preferably 5 to 50, more preferably 10 to 40. By making the difference in the hardness of the bead filler (H _out -H _in ) within such a range, the difference in rigidity between the outside and inside when the vehicle is mounted is optimized, and adverse effects on the exercise performance and durability are suppressed. be able to. In the present specification, the hardness of the bead filler refers to the rubber hardness measured at a temperature of 20 ° C. with a durometer type A in accordance with JIS K6253.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

  In the pneumatic tire of tire size 225 / 55R17, 13 types of pneumatic tires (Examples 1 to 8 and Comparative Examples 1 to 8) in which the configurations of the belt cord and the bead filler of the belt layer are changed as shown in Tables 1 and 2. 5) was produced. In Tables 1 and 2, the description in the column of “belt cord form” indicates that the belt cord is a steel cord having a linear shape or an arc shape. The description in the column of “the direction of the convex portion of the belt cord” indicates whether the direction of the convex portion of the arc in the arc-shaped belt cord is the outer side or the inner side when the vehicle is mounted. The description in the column of “belt cord angle θ” indicates an inclination angle with respect to the tire circumferential direction in the case of a linear belt cord, and an inclination angle with respect to the tire circumferential direction of a tangent at the end portion in the case of an arc belt cord. In addition, the description in the column “distance P between belt cords” indicates the distance between tire cords adjacent to each other in the tire circumferential direction in a linear belt cord, and belt cords adjacent in the tire circumferential direction in an arc belt cord. The tire circumferential direction distance between the end portions of the tire is shown.

Regarding the bead filler, the description in the “basic form” column indicates whether the basic form of the left and right bead fillers is similar to those in FIGS. 1 and 5. In Comparative Example 3, the basic configuration is such that the height of the bead filler is lower on the outer side when the vehicle is mounted than on the inner side when the vehicle is mounted. The description _in the column of “height ratio L _out / L _in ” indicates the ratio between the height L _out of the outer bead filler and the height L _in of the inner bead filler. The description _in the column of “Hardness difference H _out −H _in ” indicates a difference obtained by subtracting the hardness H _in of the inner bead filler from the hardness H _out of the outer bead filler.

  About 13 types of obtained pneumatic tires, steering stability, riding comfort, and vehicle flow were evaluated by the method shown below.

Steering stability The obtained pneumatic tire is assembled to a wheel with a rim size of 17 × 71 / 2J, mounted on a test vehicle of a domestic SUV negative camber, and a 4km round test course is performed at 120km / h under the condition of air pressure of 230kPa. The vehicle was run and the sensitivity was evaluated by three specialized panelists. The evaluation results are shown in the “Steering Stability” column of Tables 1 and 2 with a score of 5 out of 5 with Comparative Example 1 being 3 (standard). The larger the value of this score, the better the steering stability.

Riding comfort The obtained pneumatic tire is assembled to a wheel with a rim size of 17 × 71 / 2J and mounted on a test vehicle of a domestic SUV negative camber, and a straight test course with unevenness is set at 50 km / h under the condition of air pressure of 230 kPa. The vehicle was run on a vehicle, and a sensitive evaluation was conducted by three specialized panelists. The evaluation results are shown in the column of “Riding comfort” in Tables 1 and 2, assuming a comparative score of 3 (standard) and a maximum score of 5 points. The larger the value of this score, the better the ride performance.

Vehicle flow The obtained pneumatic tire is assembled to a wheel with a rim size of 17 × 71 / 2J and mounted on a test vehicle of a domestic SUV negative camber. A flat straight test course is carried out at 100 km / h under conditions of air pressure of 230 kPa. A distance (deflection amount) deviated left and right from the straight line was measured after running 100 mm from the time when the hand was released from the handle during straight running. The obtained results are shown in the column of “vehicle flow” in Tables 1 and 2 as an index for setting the reciprocal of Comparative Example 1 to 100. The larger the vehicle flow index, the smaller the deflection amount, which means that the vehicle flow is suppressed.

DESCRIPTION OF SYMBOLS 1 Tread part 3 Bead part 4 Bead core 5 Carcass layer 6 Belt layer 6i Inner end part when the belt layer is mounted on the vehicle 6o Outer end part when the belt layer is mounted on the vehicle 7 Arc-shaped belt cord 8 Bead filler 8 _in Bead when the vehicle is installed filler 8 _out vehicle when mounted height L _out vehicle mounting when the height of the outside bead filler end L _in the vehicle when mounted inside bead filler apexes e arcuate belt cord of the convex portion of the outside of the bead filler a arcuate belt cord T Pneumatic tire R Tire circumferential direction

Claims (7)

A carcass layer is mounted between the bead cores embedded in the pair of left and right bead portions, and both end portions of the carcass layer are folded back from the inside of the tire so as to wrap the bead filler around the bead core, and the carcass in the tread portion is In a pneumatic tire having a configuration in which a belt layer is disposed on the outer peripheral side of the layer, and a mounting direction with respect to the vehicle is designated,
The belt layer includes a belt cord extending in an arc shape, the arc-shaped belt cord is arranged so as to protrude outward when the vehicle is mounted, and the height L _{out of the} bead filler on the outer side when the vehicle is mounted A pneumatic tire characterized _{in that} is higher than the height L _in of the inner bead filler when the vehicle is mounted. 2. The pneumatic tire according to claim 1, wherein a ratio L _out / L _in between the height L _out and the height L _in of the bead filler is 1.05 to 3.0. A carcass layer is mounted between the bead cores embedded in the pair of left and right bead portions, and both end portions of the carcass layer are folded back from the inside of the tire so as to wrap the bead filler around the bead core, and the carcass in the tread portion is In a pneumatic tire having a configuration in which a belt layer is disposed on the outer peripheral side of the layer, and a mounting direction with respect to the vehicle is designated,
The belt layer includes a belt cord extending in an arc shape, the arc-shaped belt cord is arranged so as to protrude outward when the vehicle is mounted, and measured according to JIS K6253 of the bead filler on the outer side when the vehicle is mounted. A pneumatic tire characterized in that the hardness H _out is higher than the hardness H _in of the inner bead filler when the vehicle is mounted. The pneumatic tire according to claim 3, wherein a difference (H _out −H _in ) between the hardness H _out and the hardness H _in of the bead filler is 5 to 50. 5.   An end of the arc-shaped belt cord is positioned at an inner end of the belt layer when the vehicle is mounted, and an apex outside the arc-shaped belt cord in the tire width direction is positioned at an outer end of the belt layer when mounted on the vehicle. The pneumatic tire according to any one of claims 1 to 4, characterized in that:   The pneumatic according to any one of claims 1 to 5, wherein an angle θ of a tangent line of the arc belt cord at the inner end of the belt layer with respect to a tire circumferential direction is 50 to 90 °. tire.   At the inner end of the belt layer when the vehicle is mounted, a tire circumferential distance P between the end of the arc belt cord and the end of the arc belt cord adjacent to the tire circumferential direction is 1.5 to 4.5 mm. The pneumatic tire according to claim 1, wherein the pneumatic tire is provided.

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