JP2019055652A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire which can maintain a tire weight and a rolling resistance to be sufficiently low while improving braking property.SOLUTION: In a pneumatic tire in which a mounting direction to a vehicle is designated, a bead filler height FH1 on the vehicle inner side and a bead filler height FH2 on the vehicle outer side are made different so that the bead filler heights FH1 and FH2 satisfy a relationship of FH1>FH2, and a partial 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, and more particularly to a pneumatic tire that can maintain a sufficiently low tire weight and rolling resistance while improving braking performance.

  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). For example, in a vehicle set as a general negative camber, when the tire structure is asymmetric between the vehicle inner side and the vehicle outer side as described above, the braking performance is improved as the rigidity of the side wall portion inside the vehicle is higher. Therefore, the braking performance can be improved by increasing the bead filler height inside the vehicle.

  However, as the bead filler height increases, the amount of bead filler used increases, which adversely affects the tire weight and rolling resistance.As described above, the bead filler height is increased to improve braking performance. However, there is a problem that a sufficient effect cannot always be obtained. Therefore, in order to increase the bead filler height inside the vehicle and improve the braking performance, further improvements for maintaining 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 that can maintain a sufficiently low tire weight and rolling resistance while improving braking performance.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a tread portion that extends in the tire circumferential direction to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and the sidewall portions. A pair of bead portions disposed on the inner side in the tire radial direction, a bead core disposed between the pair of bead portions and provided in each bead portion, and a bead filler disposed on the outer periphery of the bead core. A carcass layer folded around, 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 inner surface of the tire along the carcass layer, and mounted on a vehicle In a pneumatic tire with a specified direction, the side that is on the inside of the vehicle when mounted on the vehicle is the inside of the vehicle, and that on the side that is on the vehicle is outside of the vehicle Is different from the bead filler height FH1 on the vehicle inner side and the bead filler height FH2 on the vehicle outer side, the bead filler heights FH1 and FH2 satisfy the relationship of FH1> FH2, and the carcass layer and the The partial tie rubber layer is limitedly disposed over the entire region between the inner liner layer and the region excluding the tip portions of the pair of bead portions.

  In the pneumatic tire of the present invention, the bead filler height FH1 on the vehicle inner side is larger than the bead filler height FH2 on the vehicle outer side, so that the rigidity of the sidewall portion on the vehicle inner side can be increased. Since the sidewall portion inside the vehicle contributes to the braking performance particularly in a vehicle set to a general negative camber, the braking performance can be improved by increasing the rigidity of the sidewall portion inside the vehicle in this way. At this time, the amount of the bead filler used is increased by the amount of the bead filler height FH1, and there is a concern about the influence on the tire weight and rolling resistance. However, as the tie rubber layer, the entire width between the carcass layer and the inner liner layer is increased. Adopting a partial tie rubber layer instead of a covering full tie rubber layer to reduce tire weight and rolling resistance, so even if the bead filler height FH1 is large and the amount of bead filler used is increased, the tire weight and rolling resistance are reduced. It can be maintained well. In the present invention, the “bead filler height” is a length measured along the tire radial direction from the bead heel to the outer end of the bead filler in the tire radial direction.

  In the present invention, the volume of the bead filler inside the vehicle is larger than the volume of the bead filler outside the vehicle, and the bead filler height FH1 is preferably 120% to 150% of the bead filler height FH2. By setting the size relationship of the volume of the bead filler in this way, the rigidity of the sidewall portion inside the vehicle can be reliably increased. Furthermore, by setting the ratio of the bead filler height FH1 to the bead filler height FH2, the rigidity of the sidewall portion inside the vehicle can be sufficiently and appropriately increased without deteriorating the tire weight and rolling resistance. As a result, it is advantageous to achieve a good balance between improving braking performance and reducing tire weight and rolling resistance.

  In the present invention, the rubber hardness H1 of the bead filler inside the vehicle is different from the rubber hardness H2 of the bead filler outside the vehicle, the rubber hardness H1 and H2 satisfy the relationship of H1> H2, and the rubber hardness H1 is the rubber hardness H2. It is preferable that it is 105 to 120%. By setting the magnitude relationship of the rubber hardness of the bead filler in this way, the rigidity of the sidewall portion inside the vehicle can be reliably increased. Furthermore, by setting the ratio of the rubber hardness H1 to the rubber hardness H2, the rigidity of the sidewall portion outside the vehicle can be sufficiently and appropriately increased without deteriorating the tire weight or rolling resistance. As a result, it is advantageous to achieve a good balance between improving braking performance and reducing tire weight and rolling resistance. In the present invention, the rubber hardness H1 and H2 of the bead filler is a hardness measured at a temperature of 20 ° C. by a durometer type A according to JIS K6253 (so-called JIS-A hardness).

  In the present invention, the hardnesses H1 and H2 of the rubber constituting the bead filler are preferably 70 to 100, respectively. Thus, by setting the rubber hardness of the bead filler in an appropriate range, the effect of improving the rigidity by the bead filler can be sufficiently obtained without adversely affecting the rolling resistance.

  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 in the tire width direction of the belt layer toward the inner liner layer is such that the perpendicular P and the inside of the tire It is preferably 0.25 to 0.90 times 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. 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, the protrusion amount L1 _IN at the vehicle inner end of the partial tie rubber layer is different from the protrusion amount L1 _OUT at the vehicle outer end, and these protrusion amounts L1 _IN and L1 _OUT satisfy L1 _IN > L1 _OUT . It satisfies the relationship, and the protrusion amount L1 _iN is more than 120% of the protrusion amount L1 _OUT, and the difference between these protruding amount L1 _iN and L1 _OUT is 5 mm to 30 mm. Thus, by increasing the protrusion L1 _IN on the vehicle outer side, the rigidity of the side wall portion on the vehicle inner side can be increased also by the partial tie rubber layer, which is advantageous for improving the braking performance. At this time, since the difference between the protrusion amounts L1 _IN and L1 _OUT is set to an appropriate range, the tire weight and rolling resistance can be maintained well, and the braking performance is improved and the tire weight and rolling resistance are reduced. It is advantageous to achieve both in a balanced manner.

  In the present invention, it is preferable that the tip of the bead filler and the tip of the partial tie rubber layer are separated from each other by 10 mm or more in the tire radial direction. Thereby, since the front-end | tip of the tire structural member (a bead filler 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 inner side of the partial tie rubber layer extends to a position where it overlaps with the bead filler on the vehicle inner side, and the end portion on the vehicle outer side of the partial tie rubber layer overlaps with the bead filler on the vehicle outer side. It is preferable to terminate without. As a result, the rigidity of the sidewall portion inside the vehicle can be increased efficiently, and the braking performance 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. In the present invention, the hardness of the rubber constituting the partial tie rubber is the 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 an embodiment of the present invention.

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

  As shown in FIG. 1, the pneumatic tire of the present invention includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, 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 wall 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. The pair of left and right bead fillers 6 (bead filler 61 inside the vehicle and bead filler 62 outside the vehicle) have different bead filler heights. Specifically, the bead filler height FH1 inside the vehicle and the bead filler height FH2 outside the vehicle satisfy the relationship of FH1> FH2.

  A plurality of layers (two layers in the example of FIG. 1) 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, a belt reinforcing layer 8 (a pair of belt reinforcing layers 8 covering both ends of the belt layer 7 in the example of FIG. 1) is provided on the outer peripheral side of the belt layer 7. 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 partial tie rubber layer 40 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 air permeation prevention and braking performance in a manufactured tire. The conventional tie rubber layer covers at least 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 around the bead core 5. Although the so-called full tie rubber layer is provided so as to be folded back from the vehicle inner side to the outer side, the partial tie rubber layer 40 of the present invention 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, the bead filler height FH1 of the bead filler 61 inside the vehicle is larger than the bead filler height FH2 of the bead filler 62 outside the vehicle as described above. The rigidity of the sidewall portion 2 inside the vehicle can be increased. As a result, the braking performance can be improved particularly in a vehicle set to a general negative camber. At this time, since the use amount of the bead filler 6 is increased by the amount of the bead filler height FH1, there is a concern about the influence on the tire weight and rolling resistance, but the tie rubber layer 10 includes the carcass layer 4 and the inner liner layer 9. The above-described partial tie rubber layer 10 is used instead of the conventional full tie rubber layer covering the entire width between layers to reduce the tire weight and the rolling resistance. Therefore, the bead filler height FH1 is large and the amount of the bead filler 6 used is large. Even if it increases, the tire weight and rolling resistance can be maintained well.

  At this time, if the bead filler heights FH1 and FH2 coincide with each other, or if the magnitude relationship is reversed and the relationship of FH1 <FH2 is established, the rigidity of the sidewall portion 2 inside the vehicle cannot be increased. The effect of improving the braking performance cannot be obtained.

  In setting the bead filler heights FH1 and FH2 to the relationship of FH1> FH2, the bead filler height FH1 is preferably set to 120% to 150%, more preferably 125% to 135% of the bead filler height FH2. . By setting the ratio of the bead filler height FH1 to the bead filler height FH2 in this way, the rigidity of the sidewall portion 2 inside the vehicle can be sufficiently and appropriately increased without deteriorating the tire weight or rolling resistance. This is advantageous in achieving a good balance between improving braking performance and reducing tire weight and rolling resistance. At this time, if the bead filler height FH1 is smaller than 120% of the bead filler height FH2, the rigidity of the sidewall portion 2 inside the vehicle cannot be sufficiently improved, and the effect of increasing the braking performance is limited. . If the bead filler height FH1 is larger than 150% of the bead filler height FH2, the amount of rubber increases, and therefore the tire weight and rolling resistance are adversely affected, making it difficult to sufficiently maintain these performances. In addition, the ride quality and noise vibration may be adversely affected.

  In order to make the bead filler 61 on the vehicle inner side and the bead filler 62 on the vehicle outer side asymmetric as described above, the volume V1 of the bead filler 61 on the vehicle inner side and the volume V2 of the bead filler 62 on the vehicle outer side are further made different. The volumes V1 and V2 preferably satisfy the relationship V1> V2. Thus, by increasing the volume V1 of the bead filler 61 on the vehicle inner side, the rigidity of the side wall portion 2 on the vehicle inner side can be reliably increased rather than simply increasing the bead filler height FH1 on the vehicle inner side, This is advantageous for improving the braking performance. At this time, the volume V1 is preferably 120% to 150%, more preferably 125% to 140% of the volume V2. Thus, by setting the ratio of the volume V1 to the volume V2 within an appropriate range, the tire weight and rolling resistance can be maintained well, and the balance between improved braking performance and reduced tire weight and rolling resistance is achieved. It is advantageous to achieve a good balance. At this time, if the volume V1 is smaller than 120% of the volume V2, the rigidity of the sidewall portion 2 inside the vehicle cannot be sufficiently improved, and the effect of improving the braking performance is limited. When the volume V1 is larger than 150% of the volume V2, the tire weight and rolling resistance are adversely affected, and it becomes difficult to sufficiently maintain these performances.

  The bead filler heights FH1 and FH2 are not particularly limited as long as they satisfy the above-described magnitude relationship and ratio, but in order to fully exhibit general performance as a tire, both are 15% to 40% of the tire cross-section height SH. % Is preferably set. In particular, the bead filler height FH2 may be set to 15% to 25% of the tire cross-section height SH, and the bead filler height FH1 may be set to 30% to 40% of the tire cross-section height SH. At this time, if the bead filler heights FH1 and FH2 are both smaller than 15% of the tire cross-section height SH, the bead filler 6 becomes small, which may adversely affect the original performance of the tire. In particular, since the bead filler height FH1 is small, the rigidity of the sidewall portion 2 inside the vehicle cannot be sufficiently improved, and the effect of improving the braking performance is limited. If the bead filler heights FH1 and FH2 are larger than 40% of the tire cross-section height SH, the amount of rubber increases, so the tire weight and rolling resistance are adversely affected, making it difficult to sufficiently maintain these performances. .

  In making the bead filler 61 on the vehicle inner side and the bead filler 62 on the vehicle outer side asymmetric as described above, the rubber hardness H1 of the bead filler 61 on the vehicle inner side and the rubber hardness H2 of the bead filler 62 on the vehicle outer side are further different. Thus, it is preferable that the rubber hardness H1 and H2 satisfy the relationship of H1> H2. Thus, by increasing the rubber hardness H1 of the bead filler 61 on the vehicle inner side, the rigidity of the sidewall portion 2 on the vehicle inner side can be increased more reliably than simply increasing the bead filler height FH1 on the vehicle inner side. It is advantageous for improving the braking performance. At this time, the rubber hardness H1 is preferably 105% to 120%, more preferably 110% to 115% of the rubber hardness H2. Thus, by setting the ratio of the rubber hardness H1 to the rubber hardness H2 within an appropriate range, the tire weight and rolling resistance can be maintained well, and the braking performance is improved and the tire weight and rolling resistance are reduced. It is advantageous to achieve both in a balanced manner. At this time, if the rubber hardness H1 is smaller than 105% of the rubber hardness H2, the rigidity of the sidewall portion 2 inside the vehicle cannot be sufficiently improved, and the effect of improving the braking performance is limited. If the rubber hardness H1 is greater than 120% of the rubber hardness H2, the tire weight and rolling resistance will be adversely affected, making it difficult to sufficiently maintain these performances.

  The rubber hardness H1, H2 of the bead filler is not particularly limited as long as it satisfies the above-mentioned magnitude relationship and ratio, but in order to fully exhibit the general performance as a tire, both are preferably JIS hardness of 70 to 100, More preferably, it is good to set to 75-95. At this time, if the rubber hardness H1 or H2 of the bead filler 6 is smaller than 70, the reinforcing effect by the bead filler 6 is insufficient, and the original performance of the tire may be affected. If the rubber hardness H1, H2 of the bead filler 6 is greater than 100, it is difficult to sufficiently maintain the rolling resistance.

  The partial tie rubber layer 40 has end portions on the side wall portions 2 on the vehicle inner side and the vehicle outer side, respectively. In order to prevent the carcass cord from getting into the inner liner layer 9 at the time of tire manufacture, However, it is preferable that the belt layer sufficiently protrudes from the outermost end in the tire width direction of the belt layer toward the bead portion. Specifically, the protrusion amount L1 of the partial tie rubber layer 40 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 40 in this way, even the partial tie rubber layer 40 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 protruding amount L1 is smaller than 0.25 times the peripheral length L2, the region covered by the partial tie rubber layer 40 becomes narrow, so that the effect of preventing the carcass cord from getting caught cannot be obtained sufficiently. 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 40 is increased, which is substantially equal 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 40 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 40 when the partial tie rubber layer 40 is employed, the present inventor obtains air permeation prevention and braking performance equivalent to those of a conventional pneumatic tire having a full tie rubber layer. The partial tie rubber layer 40 is at least 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 40 from the perpendicular line P to the bead part 3 side). It is known that it is preferable to cover the area between), and by setting the protrusion amount L1 to 15 mm or more as described above, this area can be reliably covered with the partial tie rubber layer 40, This is advantageous for maintaining high air permeation prevention and braking performance. At this time, when the protrusion amount L1 is less than 15 mm, the above-described region cannot be covered, and it is difficult to maintain the air permeation preventive property and the braking property well.

The partial tie rubber layer 40 may have a line-symmetric structure with respect to the tire equator CL, but the end position of the partial tie rubber layer 40 may be different between the vehicle inner side and the vehicle outer side. In particular, the protrusion amount L1 _IN at the inner end of the partial tie rubber layer 40 is different from the protrusion amount L1 _OUT at the outer end of the vehicle, and these protrusion amounts L1 _IN and L1 _OUT satisfy the relationship of L1 _IN > L1 _OUT. It is preferable. By thus increasing the protrusion amount L1 _IN in the vehicle inner side, can also increase the rigidity of the sidewall portion 2 of the vehicle interior by the partial tie rubber layer 40 is advantageous to improve the braking performance. In this case, it is the projection amount L1 _IN projecting amount L1 _OUT 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 protrusion amounts L1 _IN and L1 _OUT within an appropriate range, the tire weight and rolling resistance can be maintained well, and the braking performance is improved and the tire weight and rolling resistance are reduced. It is advantageous to achieve both in a balanced manner. In this case, the protrusion amount L1 _IN is less than 120% of the protrusion amount L1 _OUT, can not be sufficiently improved rigidity of the sidewall portion 2 on the inner side of the vehicle, the effect of enhancing the braking performance is limited. If the difference between the protruding amounts L1 _IN and L1 _OUT is smaller than 5 mm, the rigidity of the sidewall portion 2 inside the vehicle cannot be sufficiently improved, and the effect of improving the braking performance 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 40 increases, which adversely affects the tire weight and rolling resistance, making it difficult to sufficiently maintain these performances. .

  Whether the partial tie rubber layer 40 is axisymmetrical with respect to the tire equator CL or an asymmetrical structure, the front end of the bead filler 6 in the tire radial direction and the front end of the partial tie rubber layer 40 are preferably in the tire radial direction. Is 10 mm or more, more preferably 15 mm or more. In other words, the distances D1 and D2 between the tip of the bead filler 6 on the outer side in the tire radial direction and the tip of the partial tie rubber layer 40 are preferably 10 mm or more, more preferably 15 mm or more. When the tips are separated from each other, the bead filler 6 and the partial tie rubber layer 40 overlap so that the tip of the partial tie rubber layer 40 is separated from the tip of the bead filler 6 in the tire radial direction (the tip of the bead filler 6 is The bead filler 6 and the partial tie rubber layer 40 do not overlap each other, and the tip of the partial tie rubber layer 40 has a tire diameter larger than that of the bead filler 6. It may be spaced outward in the direction (the tip of the bead filler 6 is spaced further inward in the tire radial direction than the tip of the partial tie rubber layer 40). Thus, by separating the tips of the tire constituent members (the bead filler 6 and the partial tie rubber layer 40), the tips of the respective members, which are the starting points of failure such as peeling, do not come close to each other, and the durability of the tire can be improved. . At this time, if the distances D1 and D2 between the tip of the bead filler 6 and the tip of the partial tie rubber layer 40 are less than 10 mm, the tips of the tire constituent members (the bead filler 6 and the partial tie rubber layer 40) are too close to each other. There is a risk of affecting the durability of the tire.

  In particular, when the partial tie rubber layer 40 is asymmetric with respect to the tire equator CL, as shown in FIG. 1, the vehicle inner end of the partial tie rubber layer 40 extends to a position overlapping the bead filler 61 on the vehicle inner side. On the other hand, it is preferable to terminate the end portion of the partial tie rubber layer 40 on the vehicle outer side without overlapping with the bead filler 62 on the vehicle outer side. Thereby, the rigidity of the side wall part 2 inside the vehicle where the partial tie rubber layer 40 and the bead filler 6 overlap can be increased efficiently, and the braking performance can be improved effectively.

  The thickness t of the partial tie rubber layer 40 is preferably 0.1 mm to 1.3 mm, more preferably 0.3 mm to 1 in order to at least sufficiently exhibit the 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 40 in this manner, the effect of improving the rigidity by the partial tie rubber layer 40 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 40 is smaller than 0.1 mm, the reinforcing effect by the partial tie rubber layer 40 cannot be sufficiently obtained. When the thickness t of the partial tie rubber layer 40 is larger than 1.3 mm, the amount of use of the partial tie rubber layer 40 increases, which adversely affects the tire weight and rolling resistance, and it is difficult to sufficiently maintain these performances. Become.

  The hardness of the rubber constituting the partial tie rubber layer 40 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 40 in this way, the effect of improving the rigidity by the partial tie rubber layer 40 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 40 is less than 50, the reinforcing effect by the partial tie rubber layer 40 cannot be sufficiently obtained. If the hardness of the rubber constituting the partial tie rubber layer 40 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 (volume V1, V2 and rubber hardness H1, H2) of the bead filler 6 excluding the above-described relationship between the bead filler heights FH1 and FH2, and an asymmetric structure (protrusion amount) of the partial tie rubber layer 40. L1 _IN and L1 _OUT and the separation distances D1 and D2) can be used in any combination. By combining these structures, while maintaining good tire weight and rolling resistance, the rigidity of the sidewall portion 2 on the inside of the vehicle is efficiently increased to improve braking performance, and these performances are balanced in a highly balanced manner. Is possible.

The tire size is 195 / 65R15, has the basic structure shown in FIG. 1, and the bead filler has a size relationship between the bead filler height FH1 on the vehicle inner side and the bead filler height FH2 on the vehicle outer side (height FH1, FH2 ), The ratio of the bead filler height FH1 to the bead filler height FH2 (FH1 / FH2 × 100%), the size relationship (volume) of the volume V1 of the bead filler inside the vehicle and the volume V2 of the bead filler outside the vehicle V1, V2 magnitude relationship), rubber hardness H1 of the bead filler inside the vehicle and rubber hardness H2 of the bead filler outside the vehicle (magnitude relationship of hardness H1, H2), ratio of rubber hardness H1 to rubber hardness H2 (H1 / H2 × 100%) and real values of rubber hardness H1 and H2 are set as shown in Tables 1 to 3, respectively. About the structure, the protrusion amount L1 _IN / L2 inside the vehicle relative to the peripheral length L2, the protrusion amount L1 _OUT / L2 outside the vehicle relative to the peripheral length L2, the difference L1 _IN -L1 _OUT between the protrusion amounts, the rubber thickness t, the rubber The hardness is set as shown in Tables 1 to 3, and the positional relationship between the end of the bead filler and the end of the partial tie rubber layer and the end of the partial tie rubber layer (vehicle) Positional relationship on the inside), a separation distance D1 between the tip of the bead filler inside the vehicle and the tip of the partial tie rubber layer, and a positional relationship between the end of the bead filler outside the vehicle and the end of the partial tie rubber layer (positional relationship outside the vehicle) ), The separation distance D2 between the tip of the bead filler inside the vehicle and the tip of the partial tie rubber layer is set as shown in Tables 1 to 3, respectively. Conventional Example 1, Comparative Examples 1 and 2 32 types of pneumatic tire of 1 to 29 were produced.

  In the column of “structure of tie rubber layer” in Tables 1 to 3, “full” is described when the tie rubber layer is a full tie rubber layer, and “part” when the tie rubber layer is a partial tie rubber layer. In addition, regarding the columns of “position relationship inside the vehicle” and “position relationship outside the vehicle” regarding the arrangement of the end portion, the case where the end portion of the partial tie rubber layer overlaps with the bead filler is “overlap”, and the case where there is no overlap. Non-redundant ”.

In the case of the full tie rubber layers of the conventional examples 1 and 2, 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, 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”.

  About these 32 types of pneumatic tires, the tire weight, rolling resistance, and braking performance were evaluated by the following evaluation methods, and the results are also shown in Tables 1 to 3.

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.

Braking performance Each test tire is mounted on a wheel with a rim size of 15 x 6 J, mounted on a test vehicle with a displacement of 1.5 L with an air pressure of 210 kPa, and the test driver stops at a speed of 100 km / h on a test course consisting of a dry road surface. The distance (stop distance) until it was measured was measured 5 times, and the average (average stop distance) was determined. The evaluation result was shown by the index | exponent which sets the reciprocal number of the average stop distance of the prior art example 1 to 100. A larger index value means a shorter average stop distance and better braking performance.

  As is clear from Tables 1 to 3, all of Examples 1 to 29 improved the braking performance while maintaining and reducing the tire weight and rolling resistance with respect to Conventional Example 1.

  On the other hand, Comparative Example 1 can improve the braking performance because the height of the bead filler inside the vehicle is large, but since the full tie rubber layer is used as the tie rubber layer, the tire weight and the rolling resistance are kept sufficiently low. I couldn't. In Comparative Example 2, since the bead filler height on the vehicle outer side is large, the rigidity of the side wall portion on the vehicle inner side cannot be increased, and the braking performance cannot be improved.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 61 Bead filler inside a vehicle 62 Bead filler outside a vehicle 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 Partial tie rubber layer CL Tire equator IN Vehicle inside OUT Vehicle outside

Claims (10)

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 side that is the inner side with respect to the vehicle when mounted on the vehicle is the vehicle inner side, and the side that is the outer side with respect to the vehicle when mounted on the vehicle is the vehicle outer side,
The bead filler height FH1 inside the vehicle is different from the bead filler height FH2 outside the vehicle, and these bead filler heights FH1 and FH2 satisfy the relationship of FH1> FH2,
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.   The volume of the bead filler inside the vehicle is larger than the volume of the bead filler outside the vehicle, and the bead filler height FH1 is 120% to 150% of the bead filler height FH2. Pneumatic tire described in 2.   The rubber hardness H1 of the bead filler inside the vehicle is different from the rubber hardness H2 of the bead filler outside the vehicle, the rubber hardness H1 and H2 satisfy the relationship of H1> H2, and the rubber hardness H1 is equal to the rubber hardness H2. The pneumatic tire according to claim 1, wherein the pneumatic tire is 105% to 120%.   The pneumatic tire according to any one of claims 1 to 3, wherein the hardnesses H1 and H2 of the rubber constituting the bead filler are 70 to 100, respectively.   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 4, 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 _iN is not less than 120% of the protrusion amount L1 _OUT, 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 6, wherein a tip of the bead filler and a tip of the partial tie rubber layer are separated by 10 mm or more in a tire radial direction.   The end portion on the vehicle inner side of the partial tie rubber layer extends to the position where it overlaps with the bead filler on the vehicle inner side, and the end portion on the vehicle outer side of the partial tie rubber layer overlaps with the bead filler on the vehicle outer side. The pneumatic tire according to claim 7, wherein the pneumatic tire terminates without being.   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 9, wherein the rubber constituting the partial tie rubber layer has a hardness of 50 to 90.

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