JP2019055653A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire which can highly achieve well-balanced steering stability on a dry road surface, tire weight and rolling resistance.SOLUTION: In a pneumatic tire in which a mounting direction to a vehicle is designated, a bead reinforcement layer is provided on only the vehicle outer side, a periphery length r1 of the bead reinforcement layer 21 on the vehicle inner side or elastic modulus E1 and a periphery length r2 of the bead reinforcement layer 22 on the vehicle outer side or elastic modulus E1 are made different so that the periphery lengths r1 and r2 or elastic moduli E1 and E2 satisfy a relationship of r1<r2 or E1<E2, and a tie rubber layer 40 is restrictedly arranged between layers of a carcass layer 4 and an inner liner layer 9 and over the whole region excluding each tip portion of the pair of bead parts 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire in which a mounting direction with respect to a vehicle is specified. More specifically, the present invention relates to a pneumatic tire that makes it possible to achieve a high balance between steering stability, tire weight, and rolling resistance on a dry road surface. .

  2. Description of the Related Art Recently, in a pneumatic tire in which a mounting direction with respect to a vehicle is specified, the tire structure is different between a vehicle inner side which is an inner side with respect to the vehicle and a vehicle outer side which is outer with respect to the vehicle when mounted on the vehicle. The tire performance is improved (for example, see Patent Document 1). In the tire having an asymmetric structure between the vehicle inner side and the vehicle outer side as described above, the cornering power can be improved as the bending rigidity of the sidewall portion on the vehicle outer side is higher. For example, a plurality of reinforcements are provided in the bead portion. When providing a bead reinforcement layer including a cord, this bead reinforcement layer is provided only on the bead portion outside the vehicle, or the peripheral length and elastic modulus of the bead reinforcement layer outside the vehicle among the bead reinforcement layers provided inside and outside the vehicle. By relatively increasing the bend reinforcement layer, the bead reinforcement layer increases the bending rigidity of the sidewall portion outside the vehicle, and the steering stability on the dry road surface can be improved.

  However, the use of a bead reinforcement layer increases the number of tire components and adversely affects the tire weight and rolling resistance.Therefore, there is a limit to improving the steering stability with the bead reinforcement layer as described above. There was a problem that a sufficient effect could not be obtained. Therefore, in order to improve the steering stability by increasing the bending rigidity of the sidewall portion outside the vehicle by the bead reinforcement layer, further improvements for maintaining the tire weight and rolling resistance are required.

Japanese Patent Application Laid-Open No. 2007-083913

  An object of the present invention is to provide a pneumatic tire capable of achieving a high balance between steering stability, tire weight, and rolling resistance on a dry road surface.

  In order to achieve the above object, a pneumatic tire according to a first aspect of the present invention includes a tread portion that extends in the tire circumferential direction and has an annular shape, a pair of sidewall portions that are disposed on both sides of the tread portion, and these side portions. A bead core disposed on the outer periphery of the bead core and a bead core disposed between the pair of bead portions, and a bead filler disposed on an outer periphery of the bead core. A carcass layer folded around the vehicle, a belt layer disposed on the outer peripheral side of the carcass layer in the tread portion, and an inner liner layer disposed on the tire inner surface along the carcass layer, In a pneumatic tire in which the mounting direction with respect to the vehicle is specified, the side that is on the inside of the vehicle when mounted on the vehicle is the inside of the vehicle, and the side that is on the vehicle when mounted on the vehicle is the outside of the vehicle. When the outer side is the vehicle outer side, a bead reinforcing layer including a plurality of reinforcing cords is provided only on the outer bead portion of the pair of bead portions, and the bead reinforcing layer is provided between the carcass layer and the inner liner layer. The partial tie rubber layer is limitedly arranged over the entire region excluding the tip portions of the pair of bead portions.

  In order to achieve the above object, a pneumatic tire according to a second aspect of the present invention includes a tread portion extending in the circumferential direction of the tire to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, A bead core disposed on the outer periphery of the bead core and a bead core disposed between the pair of bead portions, and a bead filler disposed on an outer periphery of the bead core. A carcass layer folded around the vehicle, a belt layer disposed on the outer peripheral side of the carcass layer in the tread portion, and an inner liner layer disposed on the tire inner surface along the carcass layer, In a pneumatic tire in which the mounting direction with respect to the vehicle is specified, the side that is on the inside of the vehicle when mounted on the vehicle is the inside of the vehicle, and the side that is on the vehicle when mounted on the vehicle is the outside of the vehicle. When the outer side is the vehicle outer side, bead reinforcement layers are respectively provided on the bead portions on the vehicle inner side and the vehicle outer side, and the peripheral length r1 of the bead reinforcement layer on the inner side of the vehicle and the peripheral length r2 of the bead reinforcement layer on the outer side of the vehicle are The peripheral lengths r1 and r2 satisfy the relationship of r1 <r2, and the entire length of the region between the carcass layer and the inner liner layer, excluding the tip portions of the pair of bead portions. The partial tie rubber layer is limitedly arranged.

  In order to achieve the above object, a pneumatic tire according to a third aspect of the present invention includes a tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, A bead core disposed on the outer periphery of the bead core and a bead core disposed between the pair of bead portions, and a bead filler disposed on an outer periphery of the bead core. A carcass layer folded around the vehicle, a belt layer disposed on the outer peripheral side of the carcass layer in the tread portion, and an inner liner layer disposed on the tire inner surface along the carcass layer, In a pneumatic tire in which the mounting direction with respect to the vehicle is specified, the side that is on the inside of the vehicle when mounted on the vehicle is the inside of the vehicle, and the side that is on the vehicle when mounted on the vehicle is the outside of the vehicle. Bead reinforcement layers are provided on the bead portions on the vehicle inner side and the vehicle outer side, respectively, and the elastic modulus E1 of the bead reinforcement layer on the vehicle inner side and the elastic modulus E2 of the bead reinforcement layer on the vehicle outer side are different. These elastic moduli E1 and E2 satisfy the relationship of E1 <E2, and are partial tie rubber layers over the entire region between the carcass layer and the inner liner layer and excluding the tip portions of the pair of bead portions. Is limitedly arranged.

  In the pneumatic tire according to the present invention, the bead reinforcement layer is provided only on the vehicle outer side (first invention), and the peripheral length r2 of the bead reinforcement layer on the vehicle outer side is greater than the peripheral length r1 of the bead reinforcement layer on the vehicle inner side. Is larger (second invention) or the elastic modulus E2 of the bead reinforcing layer outside the vehicle is larger than the elastic modulus E1 of the bead reinforcing layer inside the vehicle (third invention). The rigidity of can be increased. As a result, the cornering power at the sidewall portion outside the vehicle can be increased, and the steering stability on the dry road surface can be improved. At this time, the use of a bead reinforcement layer increases the number of tire components, and the use amount of the bead reinforcement layer on the outside of the vehicle increases, so there is a concern about the influence on the tire weight and rolling resistance. As described above, the partial tie rubber layer is used instead of the full tie rubber layer covering the entire width between the carcass layer and the inner liner layer to reduce the tire weight and the rolling resistance. The tire weight and rolling resistance can be maintained well. In the present invention, the “periphery length of the bead reinforcement layer” is a length measured along the extending direction of the bead reinforcement layer in the tire meridian cross section. Further, in the present invention, the “elastic modulus of the bead reinforcing layer” is a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho) in accordance with JIS K6394, temperature 20 ° C., frequency 20 Hz, static strain 10%, dynamic It is a value measured under the condition of strain ± 0.5%.

  In 3rd invention, it is preferable that the elasticity modulus E2 of a bead reinforcement layer is 110 to 300% of the elasticity modulus E1 of a bead reinforcement layer. Thus, by setting the ratio of the elastic modulus E2 to the elastic modulus E1 within an appropriate range, the tire weight and rolling resistance can be well maintained even when the bead reinforcing layer is provided, and the steering stability on the dry road surface It is advantageous to achieve a balance between improving the tire weight and reducing the tire weight and rolling resistance.

  In the second or third aspect of the invention, the peripheral length r2 of the bead reinforcing layer on the vehicle outer side is preferably 105% to 150% of the peripheral length r1 of the bead reinforcing layer on the vehicle inner side. Thus, by setting the ratio of the peripheral length r2 to the peripheral length r1 within an appropriate range, it is possible to maintain good tire weight and rolling resistance even when a bead reinforcing layer is provided, and to control on a dry road surface. It is advantageous to achieve a balance between improving stability and reducing tire weight and rolling resistance.

  In the present invention, the height of the bead reinforcing layer is preferably 5% to 50% of the tire cross-section height SH. Thus, by setting the dimensions of the bead reinforcement layer in an appropriate range, the tire weight and rolling resistance can be maintained well even if the bead reinforcement layer is provided, and the steering stability on the dry road surface is improved and the tire This is advantageous for achieving a balance between weight and reduction of rolling resistance. In the present invention, the “height of the bead reinforcement layer” is a length measured along the tire radial direction from the tire radial inner end of the bead reinforcement layer to the tire radial outer end of the bead reinforcement layer. It is.

  In the present invention, the protrusion amount L1 of the partial tie rubber layer toward the bead portion side with respect to the perpendicular P drawn from the outermost end portion in the tire width direction of the belt layer toward the inner liner layer is the vertical line P and the tire inner surface. It is preferably 0.25 to 0.90 times the peripheral length L2 along the tire inner surface from the intersection point A to the tip point B of the bead toe. By setting the position of the end of the partial tie rubber layer in this way, even if the partial tie rubber layer does not cover the entire width between the carcass layer and the inner liner layer, it functions as a tie rubber layer (prevents the carcass cord from biting in). ) Can be reliably and highly exhibited, which is advantageous for reducing the tire weight and rolling resistance. The “projection amount” in the present invention is a so-called peripheral length measured along the extending direction of each tire component (partial tie rubber layer) in the tire meridian cross section.

In the present invention, is different from the projection amount L1 _OUT in projection amount L1 _IN and the vehicle outer side end portion in the vehicle inside end portion of the part tie rubber layer, the relationship of these projection amount L1 _IN and L1 _OUT is L1 _IN <L1 _OUT the filled, and the protrusion amount L1 _OUT is more than 120% of the protrusion amount L1 _iN, and the difference between these protruding amount L1 _iN and L1 _OUT is 5 mm to 30 mm. By thus increasing the protrusion amount L1 _OUT of the vehicle outer side, it can also increase the rigidity of the sidewall portion on the vehicle outer side by the partial tie rubber layer, which is advantageous in enhancing the steering stability on dry road surface. At this time, since the difference between the protruding amounts L1 _IN and L1 _OUT is set to an appropriate range, the tire weight and rolling resistance can be maintained well, and the steering stability on the dry road surface and the tire weight and This is advantageous for achieving a good balance between reducing rolling resistance.

  In the present invention, it is preferable that the tip of the bead reinforcing layer on the outer side in the tire radial direction and the tip of the partial tie rubber layer are separated by 10 mm or more in the tire radial direction. Thereby, since the front-end | tip of the tire structural member (a bead reinforcement layer and partial tie rubber) used as the starting point of failures, such as peeling, becomes close, durability of a tire can be improved.

  At this time, the end portion on the vehicle outer side of the partial tie rubber layer extends to the position overlapping with the bead reinforcement layer on the vehicle outer side, and the end portion on the vehicle inner side of the partial tie rubber layer extends with the bead reinforcement layer on the vehicle inner side. It is preferable to terminate without overlapping. As a result, the rigidity of the sidewall portion outside the vehicle can be efficiently increased, and the steering stability on the dry road surface can be effectively improved.

  In the present invention, the partial tie rubber layer preferably has a thickness of 0.1 mm to 1.3 mm. By setting the thickness of the partial tie rubber layer in this manner, the effect of improving the rigidity by the partial tie rubber layer can be sufficiently obtained without adversely affecting the tire weight and rolling resistance. In the present invention, the “rubber thickness” is an average thickness obtained by dividing the cross-sectional area of each partial tie rubber layer by the peripheral length of each partial tie rubber layer in the meridian cross section.

  In this invention, it is preferable that the hardness of the rubber which comprises a partial tie rubber layer is 50-90. By setting the hardness of the partial tie rubber layer in this manner, the effect of improving the rigidity by the partial tie rubber layer can be sufficiently obtained without adversely affecting the tire weight and rolling resistance. The “rubber hardness” in the present invention is a hardness (so-called JIS-A hardness) measured at a temperature of 20 ° C. by a durometer type A in accordance with JIS K6253.

1 is a meridian cross-sectional view of a pneumatic tire according to a first embodiment of the present invention. It is meridian sectional drawing of the pneumatic tire which consists of 2nd embodiment of this invention. It is meridian sectional drawing of the pneumatic tire which consists of 3rd embodiment of this invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIGS. 1 to 3, the pneumatic tire of the present invention includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, and a pair of sidewall portions 2 that are disposed on both sides of the tread portion 1. And a pair of bead portions 3 disposed inside the sidewall portion 2 in the tire radial direction. In FIG. 1, CL indicates the tire equator. As for this pneumatic tire, the mounting direction with respect to the vehicle is designated. Specifically, the IN side in the figure is the side designated to be inside the vehicle when mounted on the vehicle (hereinafter referred to as the vehicle inside), and the OUT side in the figure is attached to the vehicle when mounted on the vehicle. On the other hand, it is the side designated to be outside (hereinafter referred to as the vehicle outside). Such a mounting direction can be determined, for example, by looking at a display provided at an arbitrary part on the outer surface of the tire.

  A carcass layer 4 is mounted between the pair of left and right bead portions 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back around the bead core 5 disposed in each bead portion 3 from the vehicle inner side to the outer side. A bead filler 6 is disposed on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by the main body portion and the folded portion of the carcass layer 4.

  A plurality of layers (two layers in the illustrated example) of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. Each belt layer 7 includes a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and is disposed so that the reinforcing cords cross each other between the layers. In these belt layers 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 10 ° to 40 °. Further, on the outer peripheral side of the belt layer 7, a belt reinforcing layer 8 (a pair of belt reinforcing layers 8 covering both ends of the belt layer 7 in the illustrated example) is provided. The belt reinforcing layer 8 includes an organic fiber cord oriented in the tire circumferential direction. In the belt reinforcing layer 8, the organic fiber cord has an angle with respect to the tire circumferential direction set to, for example, 0 ° to 5 °. An inner liner layer 9 is provided on the inner surface of the tire. The inner liner layer 9 is made of a rubber composition mainly composed of butyl rubber having air permeation preventing performance, and prevents air filled in the tire from permeating out of the tire.

  A tread rubber layer 10 is disposed on the outer peripheral side of the carcass layer 4 in the tread portion 1, and a side rubber layer 20 is disposed on the outer peripheral side (outer side in the tire width direction) of the carcass layer 4 in the sidewall portion 2. A rim cushion rubber layer 30 is disposed on the outer peripheral side (outer side in the tire width direction) of the carcass layer 4. The tread rubber layer 10 may have a structure in which two types of rubber layers having different physical properties (cap tread rubber layer, under tread rubber layer) are laminated in the tire radial direction.

  A bead reinforcing layer 40 is provided on the bead portion 3. In the first embodiment shown in FIG. 1, the bead reinforcement layer 40 is provided only on the bead portion 3 on the vehicle outer side, and the bead reinforcement layer 40 is not provided on the bead portion 3 on the vehicle inner side. In the second embodiment shown in FIG. 2, the bead reinforcement layer 40 is provided on each of the bead portions 3 on the vehicle inner side and the vehicle outer side, but the peripheral length r1 of the bead reinforcement layer 41 on the vehicle inner side and the bead reinforcement layer on the vehicle outer side. Unlike the peripheral length r2 of 42, the peripheral lengths r1 and r2 satisfy the relationship r1 <r2. In the third embodiment shown in FIG. 3, the bead reinforcement layer 40 is provided on each of the bead portions 3 on the vehicle inner side and the vehicle outer side as in the second embodiment. And the elastic modulus E2 of the bead reinforcement layer 42 on the vehicle outer side are different, and the elastic moduli E1 and E2 satisfy the relationship of E1 <E2. In the example of FIG. 3, the peripheral lengths r1 and r2 of the bead reinforcing layers 41 and 42 are the same. However, in the third embodiment, the peripheral lengths r1 and r2 are r1 <r2. It may be satisfied.

  The bead reinforcement layer 40 is configured by aligning a plurality of reinforcement cords inclined with respect to the tire circumferential direction and embedding them in rubber. The inclination angle of the reinforcing cord with respect to the tire circumferential direction may be set to 10 ° to 40 °, for example. As the reinforcing cord, for example, an organic fiber cord made of an organic fiber such as an aramid fiber, a polyethylene fiber, or a nylon fiber, a glass fiber cord, a steel cord, or the like can be used. In the third embodiment described above, for example, the material constituting the reinforcement cord is made different between the bead reinforcement layer 41 on the vehicle inner side and the bead reinforcement layer 42 on the vehicle outer side, or the reinforcement cord is a twisted cord. The elastic modulus E1, E2 can be made different by making the number of twists different between the bead reinforcement layer 41 inside the vehicle and the bead reinforcement layer 42 outside the vehicle.

  In the example of FIGS. 1 to 3, the bead reinforcing layer 40 is disposed on the outer side in the tire width direction of the bead filler 6 and between the bead filler 6 and the carcass layer 4. It is not limited. For example, the rubber layer and the carcass positioned between the carcass layer 4 and the inner liner layer 9, between the bead filler 6 and the carcass layer 4 (inside the bead filler 6 in the tire width direction), and outside the carcass layer 4 in the tire width direction. When two or more carcass layers 4 are provided, it can be disposed between the layers 4 and the carcass layers 4.

  A partial tie rubber layer 50 is disposed between the inner liner layer 9 and the carcass layer 4. The tie rubber layer disposed between the inner liner layer 9 and the carcass layer 4 prevents the carcass cord from biting into the inner liner layer 9 when inflating an unvulcanized pneumatic tire during tire manufacture. This layer contributes to the prevention of air permeation and steering stability on dry road surfaces in the manufactured tire. The conventional tie rubber layer covers the entire region between the carcass layer 4 and the inner liner layer 9 (the entire region between the tips of the bead portions 3 on the vehicle inner side and the vehicle outer side), and more preferably the vehicle around the bead core 5. Although the so-called full tie rubber layer is provided so as to be folded back from the inside to the outside, in the present invention, the partial tie rubber layer 50 is provided only in a region excluding the tip of the bead portion 3.

  In the pneumatic tire of the present invention configured as described above, when the bead reinforcement layer 40 is provided, the bead reinforcement layer 40 is provided only on the outside of the vehicle (first embodiment), or the peripheral of the bead reinforcement layer 42 on the outside of the vehicle. The length r2 is set larger than the peripheral length r1 of the bead reinforcement layer 41 on the vehicle inner side (second embodiment), or the elastic modulus E2 of the bead reinforcement layer 42 on the vehicle outer side is set to the bead reinforcement layer 41 on the vehicle inner side. By making it larger than the elastic modulus E1 (third embodiment), the rigidity of the sidewall portion 2 outside the vehicle can be increased. As a result, the cornering power in the sidewall portion 2 outside the vehicle can be increased, and the steering stability on the dry road surface can be improved. At this time, the use of the bead reinforcement layer 40 increases the number of tire constituent members, and the use amount of the bead reinforcement layer 40 on the outside of the vehicle relatively increases, which may affect the tire weight and rolling resistance. However, as the tie rubber layer, a partial tie rubber layer 50 is employed instead of a full tie rubber layer covering the entire width between the carcass layer 4 and the inner liner layer 9 to reduce the tire weight and the rolling resistance. Even with the structure of the bead reinforcing layer 40, the tire weight and rolling resistance can be maintained well.

  At this time, the peripheral lengths r1 and r2 of the bead reinforcement layer 40 in the second embodiment are matched, or the elastic moduli E1 and E2 of the bead reinforcement layer 40 are matched in the third embodiment. If the magnitude relationship is reversed and r1> r2 or E1> E2, the rigidity of the sidewall portion 2 outside the vehicle cannot be increased, and the effect of improving the steering stability on the dry road surface can be obtained. Absent.

  In setting the peripheral lengths r1 and r2 of the bead reinforcing layer 40 to the relationship r1 <r2, the peripheral length r2 is preferably set to 105% to 300%, more preferably 110% to 150% of the peripheral length r1. Good. By setting the ratio of the peripheral length r2 to the peripheral length r1 in this way, the rigidity of the sidewall portion 2 outside the vehicle can be sufficiently and moderately increased without deteriorating the tire weight and rolling resistance. It is advantageous to achieve a good balance between improving steering stability on a dry road surface and reducing tire weight and rolling resistance. At this time, if the peripheral length r2 is smaller than 105% of the peripheral length r1, the rigidity of the sidewall portion 2 outside the vehicle cannot be sufficiently improved, and the effect of improving the steering stability is limited. If the peripheral length r2 is larger than 300% of the peripheral length r1, the use amount of the bead reinforcing layer 40 increases, which adversely affects the tire weight and rolling resistance, and it is difficult to sufficiently maintain these performances. Become. In addition, the ride quality and noise vibration may be adversely affected.

  In setting the elastic moduli E1 and E2 of the bead reinforcing layer 40 to a relationship of E1 <E2, the elastic modulus E2 is preferably set to 110% to 300%, more preferably 110% to 200% of the elastic modulus E1. Thus, by setting the ratio of the elastic modulus E2 to the elastic modulus E1, the rigidity of the sidewall portion 2 outside the vehicle can be sufficiently and appropriately increased without deteriorating the rolling resistance, and the steering stability on the dry road surface can be improved. It is advantageous to achieve both the improvement of the property and the reduction of the tire weight and rolling resistance in a balanced manner. At this time, if the elastic modulus E2 is smaller than 110% of the elastic modulus E1, the rigidity of the sidewall portion 2 outside the vehicle cannot be sufficiently improved, and the effect of improving the steering stability is limited. If the elastic modulus E2 is larger than 300% of the elastic modulus E1, the rolling resistance is adversely affected, and it becomes difficult to achieve both steering stability and rolling resistance. The elastic moduli E1 and E2 can be set to arbitrary values as long as the above relationship is satisfied. However, in order to sufficiently exhibit the above-described effect as a reinforcing layer in a pneumatic tire, the elastic modulus E1 May be set to 7 GPa or more, for example.

  The bead reinforcing layer 40 can be configured in the manner shown in the above-described first to third embodiments, but in any case, the function of the tire is sufficiently exerted and the general performance of the tire is hindered. The height RH1 of the bead reinforcement layer 41 inside the vehicle and the height RH2 of the bead reinforcement layer 42 outside the vehicle are preferably 5% to 55%, more preferably 15% to 45% of the tire cross-section height SH. It is good to constitute so that. In particular, when the bead reinforcement layer 40 is provided only outside the vehicle as in the first embodiment, the height RH2 of the bead reinforcement layer 40 may be set to 10% to 35% of the tire cross-section height SH. Further, when the height RH1 of the bead reinforcement layer 41 on the vehicle inner side and the height RH2 of the bead reinforcement layer 42 on the vehicle outer side are made different from each other as in the second embodiment, the height RH1 is set to 15 which is the tire cross-section height SH. % To 35% and the height RH2 may be set to 25% to 45% of the tire cross-section height SH. At this time, if the heights RH1 and RH2 of the bead reinforcement layer 40 are both less than 5% of the tire cross-section height SH, the effect of providing the bead reinforcement layer 40 cannot be sufficiently obtained. If the height RH1 or RH2 of the bead reinforcement layer 40 is greater than 45% of the tire cross-section height SH, the amount of the bead reinforcement layer 40 used increases, which adversely affects the tire weight and rolling resistance. It becomes difficult to maintain enough.

  The partial tie rubber layer 50 has end portions on the side wall portions 2 on the vehicle inner side and the vehicle outer side, respectively. In order to reliably prevent the carcass cord from getting into the inner liner layer 9 during tire manufacture, However, it is preferable that the belt layer 7 sufficiently protrudes from the outermost end portion in the tire width direction to the bead portion 3 side. Specifically, the protrusion amount L1 of the partial tie rubber layer 50 toward the bead portion 3 with respect to the perpendicular P drawn from the outermost end portion in the tire width direction of the belt layer 7 toward the inner liner layer 9 is expressed as follows. The peripheral length L2 along the tire inner surface from the intersection A with the surface to the tip point B of the bead toe is preferably 0.25 to 0.90 times, more preferably 0.30 to 0.70 times. . By setting the position of the end portion of the partial tie rubber layer 50 in this way, even the partial tie rubber layer 50 that does not cover the entire width between the carcass layer 4 and the inner liner layer 9 functions as a tie rubber layer (carcass cord Can be reliably and satisfactorily exhibited, which is advantageous for reducing the tire weight and rolling resistance. At this time, if the protrusion amount L1 is smaller than 0.25 times the peripheral length L2, the region covered by the partial tie rubber layer 50 becomes narrow, and thus the effect of preventing the carcass cord from being caught can not be sufficiently obtained. If the protrusion amount L1 is larger than 0.90 times the peripheral length L2, the amount of use of the partial tie rubber layer 50 is increased, which is substantially equivalent to the full tie rubber layer, and this adversely affects the tire weight and rolling resistance. It becomes difficult to maintain these performances sufficiently.

  The protrusion amount L1 of the partial tie rubber layer 50 not only satisfies the above range, but is preferably 15 mm or more. As a result of earnest research on the arrangement of the partial tie rubber layer 50 when the partial tie rubber layer 50 is employed, the present inventor has obtained the same air permeation prevention performance and steering stability as a pneumatic tire having a conventional full tie rubber layer. Is a specific region in the vicinity of the outermost end in the tire width direction of the belt layer 7 (the position of the perpendicular line P and the position of 15 mm along the partial tie rubber layer 50 from the perpendicular line P to the bead part 3 side). It is known that it is preferable to cover the region between the two), and by setting the protrusion L1 to 15 mm or more as described above, this region can be reliably covered by the partial tie rubber layer 50. Therefore, it is advantageous to maintain a high level of air permeation prevention and steering stability. At this time, if the protrusion amount L1 is less than 15 mm, the above-described region cannot be covered, and it becomes difficult to maintain the air permeation prevention property and the steering stability well.

The partial tie rubber layer 50 may have a line-symmetric structure with respect to the tire equator CL, but the end position of the partial tie rubber layer 50 may be different between the vehicle inner side and the vehicle outer side. In particular, the protruding amount L1 _IN at the inner end of the partial tie rubber layer 50 is different from the protruding amount L1 _OUT at the outer end of the vehicle, and these protruding amounts L1 _IN and L1 _OUT satisfy the relationship L1 _IN <L1 _OUT. It is preferable. Thus, by increasing the protrusion amount L1 _OUT on the outside of the vehicle, the rigidity of the sidewall portion 2 on the outside of the vehicle can be increased also by the partial tie rubber layer 50, which is advantageous for improving the steering stability on the dry road surface. . In this case, it is the projection amount L1 _OUT projecting amount L1 _IN preferably 120% or more of the difference between the protrusion amount L1 _IN and the protrusion amount L1 _OUT is preferably 5 mm to 30 mm, may more preferably at 15mm~25mm . Thus, by setting the difference between the protruding amounts L1 _IN and L1 _OUT within an appropriate range, the tire weight and rolling resistance can be maintained well, and the steering stability on the dry road surface and the tire weight and rolling are improved. It is advantageous to achieve a balance between resistance reduction and a good balance. At this time, if the protrusion amount L1 _OUT is less than 120% of the protrusion amount L1 _IN , the rigidity of the sidewall portion 2 outside the vehicle cannot be sufficiently improved, and the effect of improving the steering stability is limited. . If the difference between the protruding amounts L1 _IN and L1 _OUT is less than 5 mm, the rigidity of the sidewall portion 2 outside the vehicle cannot be sufficiently improved, and the effect of improving the steering stability is limited. If the difference between the protruding amounts L1 _IN and L1 _OUT is larger than 30 mm, the amount of use of the partial tie rubber layer 50 is increased, which adversely affects the tire weight and rolling resistance, making it difficult to sufficiently maintain these performances. .

  Whether the partial tie rubber layer 50 is axisymmetrical with respect to the tire equator CL or an asymmetrical structure, the front end of the bead reinforcing layer 40 in the tire radial direction and the front end of the partial tie rubber layer 50 are in the tire radial direction. The distance is preferably 10 mm or more, more preferably 15 mm or more. In other words, the distances D1 and D2 between the front end of the bead reinforcing layer 40 in the tire radial direction and the front end of the partial tie rubber layer 50 are preferably 10 mm or more, more preferably 15 mm or more. When the tips are separated from each other, the bead reinforcing layer 40 and the partial tie rubber layer 50 are overlapped so that the tip of the partial tie rubber layer 50 is spaced further inward in the tire radial direction than the tip of the bead reinforcing layer 40 on the outer side in the tire radial direction. (The tip of the bead reinforcement layer 40 on the outer side in the tire radial direction may be separated from the tip of the partial tie rubber layer 50 toward the outer side in the tire radial direction), and the bead reinforcement layer 40 and the partial tie rubber layer 50 do not overlap with each other. The tip of the layer 50 is spaced further radially outward than the tip of the bead reinforcement layer 40 on the outer side in the tire radial direction (the tip of the bead reinforcement layer 40 on the outer side in the tire radial direction is located on the inner side of the partial tie rubber layer 50 in the tire radial direction) May be separated). By separating the tips of the tire constituent members (the bead reinforcement layer 40 and the partial tie rubber layer 50) in this way, the tips of the respective members that become the starting point of failure such as peeling do not come close to each other, thereby improving the durability of the tire. it can. At this time, if the distances D1 and D2 between the tip of the bead reinforcement layer 40 and the tip of the partial tie rubber layer 50 are less than 10 mm, the tips of the tire constituent members (the bead reinforcement layer 40 and the partial tie rubber layer 50) approach each other. Therefore, the durability of the tire may be affected.

  In particular, when making the partial tie rubber layer 50 asymmetric with respect to the tire equator CL, as shown in FIGS. 1 to 3, the position of the vehicle outer end portion of the partial tie rubber layer 50 overlapping the bead reinforcement layer 42 on the vehicle outer side. It is preferable that the end portion on the vehicle inner side of the partial tie rubber layer 50 is terminated without overlapping with the bead reinforcing layer 41 on the vehicle inner side, as shown in FIGS. Thereby, the rigidity of the sidewall portion 2 outside the vehicle where the partial tie rubber layer 50 and the bead reinforcing layer 40 overlap can be efficiently increased, and the steering stability on the dry road surface can be effectively improved.

  The thickness t of the partial tie rubber layer 50 is preferably 0.1 mm to 1.3 mm, more preferably 0.3 mm to 1 in order to at least sufficiently function as a tie rubber layer (preventing carcass cord biting). It is good to make it 1 mm. By setting the thickness t of the partial tie rubber layer 50 in this way, the effect of improving the rigidity by the partial tie rubber layer 50 can be sufficiently obtained without adversely affecting the tire weight and rolling resistance. At this time, if the thickness t of the partial tie rubber layer 50 is smaller than 0.1 mm, the reinforcing effect by the partial tie rubber layer 50 cannot be sufficiently obtained. If the thickness t of the partial tie rubber layer 50 is larger than 1.3 mm, the amount of use of the partial tie rubber layer 50 is increased, which adversely affects the tire weight and rolling resistance, and it is difficult to maintain these performances sufficiently. Become.

  The hardness of the rubber constituting the partial tie rubber layer 50 is preferably 50 to 90, more preferably 70 to 80, in order to at least sufficiently exhibit the function as a tie rubber layer (preventing carcass cord biting). By setting the hardness of the rubber constituting the partial tie rubber layer 50 in this way, the effect of improving the rigidity by the partial tie rubber layer 50 can be sufficiently obtained without adversely affecting the tire weight and rolling resistance. At this time, if the hardness of the rubber constituting the partial tie rubber layer 50 is less than 50, the reinforcing effect by the partial tie rubber layer 50 cannot be sufficiently obtained. If the hardness of the rubber constituting the partial tie rubber layer 50 is greater than 90, the tire weight and rolling resistance will be adversely affected, making it difficult to sufficiently maintain these performances.

In the present invention, an additional asymmetric structure (periphery length) of the bead reinforcement layer 40 excluding the above-described asymmetric structure of the bead reinforcement layer 40 (existence of inside / outside vehicle, peripheral lengths r1, r2 and magnitudes of elastic modulus E1, E2). (Ratio r1, r2, ratio of elastic modulus E1, E2, height RH1, RH2) and asymmetric structure of partial tie rubber layer 50 (projection amounts L1 _IN , L1 _OUT and separation distances D1, D2) are adopted in any combination. be able to. By combining these structures, while maintaining good tire weight and rolling resistance, the rigidity of the sidewall part 2 outside the vehicle is efficiently increased to improve the handling stability on dry road surfaces, and these performances are highly balanced. It becomes possible to balance well.

The tire size is 195 / 65R15, and has the basic structure shown in FIGS. 1 to 3, and the bead reinforcement layer is arranged, the peripheral length r1 of the bead reinforcement layer inside the vehicle, and the peripheral length of the bead reinforcement layer inside the vehicle. The size relationship of the depth r2 (the size relationship of the peripheral lengths r1 and r2), the real length (mm) of the peripheral length r1 and the peripheral length r2, and the ratio of the peripheral length r2 to the peripheral length r1 (r2 / r1 × 100) %), The magnitude relationship between the elastic modulus E1 of the bead reinforcing layer inside the vehicle and the elastic modulus E2 of the bead reinforcing layer inside the vehicle (the magnitude relationship between the elastic modulus E1 and E2), and the ratio of the elastic modulus E2 to the elastic modulus E1 (E2 / E1 × 100%), the ratio of the height RH1 of the bead reinforcement layer to the tire cross-section height SH (RH1 / SH × 100%), the bead reinforcement layer relative to the tire cross-section height SH Ratio of the height RH2 the (RH2 / SH × 100%) is set as each table 1-5, the tie rubber layer, the structure, the projection amount of the vehicle inner side relative to periphery length L2 L1 _IN / L2, periphery length The amount of protrusion L1 _OUT / L2 on the outside of the vehicle with respect to L2, the difference L1 _OUT -L1 _{IN of} the amount of protrusion, the rubber thickness t and the rubber hardness are set as shown in Tables 1 to 5, respectively, and the bead reinforcement layer and the partial tie rubber layer As for the arrangement of each end, the positional relationship between the end of the bead reinforcement layer inside the vehicle and the end of the partial tie rubber layer (the positional relationship inside the vehicle), the tip of the bead reinforcement layer inside the vehicle and the tip of the partial tie rubber layer , A positional relationship between the end of the bead reinforcement layer on the vehicle outer side and the end of the partial tie rubber layer (a positional relationship on the vehicle outer side), a tip of the bead reinforcement layer on the vehicle inner side, and a tip of the partial tie rubber layer Were set as shown in Tables 1 to 5 respectively, and 49 types of pneumatic tires of Conventional Examples 1 to 4, Comparative Examples 1 to 5, and Examples 1 to 40 were produced.

  In addition, about the column of "arrangement of bead reinforcement layer" of Tables 1-5, when a bead reinforcement layer is provided only in the bead part inside a vehicle, it is "inside" and a bead reinforcement layer is provided only in the bead part outside a vehicle. “Outer side” when it is applied, and “behind both sides” when the bead reinforcement layer is provided on the bead portion inside the vehicle and outside the vehicle, respectively. In the column of “Tie rubber layer structure” in Tables 1 to 5, “Full” was described when the tie rubber layer was a full tie rubber layer, and “Part” when the tie rubber layer was a partial tie rubber layer.

In the case of the full tie rubber layers of the conventional examples 1 to 4, since the end portion of the partial tie rubber layer extends to the tip of the bead portion and is further folded around the bead filler, the relationship of L1 _IN = L2 and L1 _OUT = L2 L1 _IN and L1 _OUT are larger than L2, and the protrusion amounts L1 _IN / L2 and L1 _OUT / L2 are both “1.1” exceeding “1.0”.

  For these 49 types of pneumatic tires, the tire weight, rolling resistance, and steering stability on the dry road surface (steering stability) were evaluated by the following evaluation methods, and the results are also shown in Tables 1 to 5.

Tire Weight The weight of each test tire was measured. The evaluation results are shown as an index with the reciprocal of the measured value of Conventional Example 1 being 100. A larger index value means a smaller tire weight. If the index value is “95” or higher, it means that the conventional level is maintained and a sufficiently small tire weight is maintained.

Rolling resistance Each test tire is assembled on a wheel with a rim size of 15 × 6J, and in accordance with ISO28580, using a drum testing machine with a drum diameter of 1707.6 mm, rolling under conditions of air pressure 210 kPa, load 4.82 kN, speed 80 km / h. Resistance was measured. The evaluation results are shown as an index with the reciprocal of the measured value of Conventional Example 1 being 100. It means that rolling resistance is so low that this index value is large. If the index value is “95” or more, it means that the conventional level is maintained and a sufficiently low rolling resistance is maintained.

Steering stability Each test tire was assembled to a wheel with a rim size of 15 × 6J, mounted on a test vehicle with a displacement of 1.5L with an air pressure of 210 kPa, and a sensory evaluation was performed by a test driver on a test course consisting of a dry road surface. . The evaluation results are shown as an index with Conventional Example 1 as 100. The larger the index value, the better the steering stability on the dry road surface.

  As is clear from Tables 1 to 5, all of Examples 1 to 40 improved the steering stability while maintaining and reducing the tire weight and rolling resistance with respect to Conventional Example 1. On the other hand, in all of the conventional examples 2 to 4, the rigidity of the sidewall portion outside the vehicle is increased by setting the peripheral length and elastic modulus of the bead reinforcement layer, so that the steering stability can be improved. Therefore, the tire weight and rolling resistance could not be kept sufficiently low. In all of Comparative Examples 1 to 5, the rigidity of the sidewall portion outside the vehicle is not increased by the arrangement of the bead reinforcement layer, the peripheral length, and the elastic modulus, and the rigidity of the sidewall portion inside the vehicle is increased. As a result, steering stability could not be improved.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt reinforcement layer 9 Inner liner layer 10 Tread rubber layer 20 Side rubber layer 30 Rim cushion rubber layer 40 Bead reinforcement layer 41 Bead inside vehicle Reinforcement layer 42 Bead exterior reinforcement layer CL Tire equator IN Vehicle interior OUT Vehicle exterior

Claims (12)

An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portions. A carcass layer folded between a bead core provided between the pair of bead portions and provided on each bead portion and a bead filler disposed on an outer periphery of the bead core, and the carcass in the tread portion. In a pneumatic tire having a belt layer arranged on the outer peripheral side of the layer and an inner liner layer arranged on the tire inner surface along the carcass layer, and a mounting direction with respect to the vehicle is designated,
When the vehicle inner side is defined as the vehicle inner side when mounted on the vehicle, and the vehicle outer side is defined as the vehicle outer side when mounted on the vehicle, the outer side of the pair of bead portions A bead reinforcement layer including a plurality of reinforcement cords is provided only on the bead portion, and is a portion extending across the entire region between the carcass layer and the inner liner layer and excluding the tip portions of the pair of bead portions. A pneumatic tire characterized by a limited arrangement of tie rubber layers. An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portions. A carcass layer folded between a bead core provided between the pair of bead portions and provided on each bead portion and a bead filler disposed on an outer periphery of the bead core, and the carcass in the tread portion. In a pneumatic tire having a belt layer arranged on the outer peripheral side of the layer and an inner liner layer arranged on the tire inner surface along the carcass layer, and a mounting direction with respect to the vehicle is designated,
When the vehicle is mounted on the vehicle, the inner side is the vehicle inner side, and when the vehicle is mounted on the vehicle, the outer side is the vehicle outer side. A bead reinforcing layer is provided, and the peripheral length r1 of the bead reinforcing layer inside the vehicle is different from the peripheral length r2 of the bead reinforcing layer outside the vehicle, and the peripheral lengths r1 and r2 satisfy the relationship r1 <r2. A pneumatic tire characterized in that a partial tie rubber layer is disposed in a limited manner over the entire region between the carcass layer and the inner liner layer and excluding the tip portions of the pair of bead portions. An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portions. A carcass layer folded between a bead core provided between the pair of bead portions and provided on each bead portion and a bead filler disposed on an outer periphery of the bead core, and the carcass in the tread portion. In a pneumatic tire having a belt layer arranged on the outer peripheral side of the layer and an inner liner layer arranged on the tire inner surface along the carcass layer, and a mounting direction with respect to the vehicle is designated,
When the vehicle is mounted on the vehicle, the inner side is the vehicle inner side, and when the vehicle is mounted on the vehicle, the outer side is the vehicle outer side. A bead reinforcing layer is provided, the elastic modulus E1 of the bead reinforcing layer inside the vehicle is different from the elastic modulus E2 of the bead reinforcing layer outside the vehicle, and these elastic moduli E1 and E2 satisfy the relationship of E1 <E2, and the carcass layer A pneumatic tire characterized in that a partial tie rubber layer is disposed between the inner liner layer and the inner liner layer over the entire region excluding the tip portions of the pair of bead portions.   The pneumatic tire according to claim 3, wherein an elastic modulus E2 of the bead reinforcing layer outside the vehicle is 110% to 300% of an elastic modulus E1 of the bead reinforcing layer inside the vehicle.   The pneumatic tire according to any one of claims 2 to 4, wherein the peripheral length r2 of the bead reinforcing layer outside the vehicle is 105% to 300% of the peripheral length r1 of the bead reinforcing layer inside the vehicle. .   The pneumatic tire according to any one of claims 1 to 5, wherein a height of the bead reinforcing layer is 5% to 50% of a tire cross-section height SH.   The amount of protrusion L1 of the partial tie rubber layer toward the bead portion with respect to the perpendicular P drawn from the outermost end in the tire width direction of the belt layer toward the inner liner layer is an intersection of the perpendicular P and the tire inner surface. The pneumatic tire according to any one of claims 1 to 6, wherein the pneumatic tire is 0.25 to 0.90 times the peripheral length L2 along the tire inner surface from A to the tip point B of the bead toe. The protruding amount L1 _IN at the vehicle inner end of the partial tie rubber layer is different from the protruding amount L1 _OUT at the vehicle outer end, and these protruding amounts L1 _IN and L1 _OUT satisfy the relationship of L1 _IN <L1 _OUT. the amount L1 _OUT is not less than 120% of the protrusion amount L1 _iN, pneumatic tire according to claim 1, difference between these protruding amount L1 _iN and L1 _OUT is characterized in that it is a 5mm~30mm .   The pneumatic tire according to any one of claims 1 to 8, wherein a tip of the bead reinforcing layer on the outer side in the tire radial direction and a tip of the partial tie rubber layer are separated from each other by 10 mm or more in the tire radial direction.   The end portion on the vehicle outer side of the partial tie rubber layer extends to a position overlapping with the bead reinforcement layer on the vehicle outer side, and the end portion on the vehicle inner side of the partial tie rubber layer is the bead reinforcement layer on the vehicle inner side The pneumatic tire according to claim 9, which terminates without overlapping with the tire.   The pneumatic tire according to claim 1, wherein the partial tie rubber layer has a thickness of 0.1 mm to 1.3 mm.   The pneumatic tire according to any one of claims 1 to 11, wherein the hardness of the rubber constituting the partial tie rubber layer is 50 to 90.

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