JP2015174594A - pneumatic tire - Google Patents

Abstract

A pneumatic tire having a reduced tire mass while maintaining steering stability is provided.
A pneumatic tire includes a carcass and an inner liner. The sidewall portion 3 includes a thinnest portion 13 having a thickness of 2.0 mm or less. In the buttress area 14, an insulation layer 20 is disposed between the inner liner 11 and the carcass 6. The insulation layer 20 is made of rubber that is harder than the inner liner 11 and has a JISA hardness Hi of 50 to 98 °.
[Selection] Figure 2

Description

  The present invention relates to a pneumatic tire in which tire mass is reduced while maintaining steering stability.

  In recent years, it has been required to reduce the weight of pneumatic tires and improve fuel efficiency (see, for example, Patent Document 1 below). However, a pneumatic tire in which each rubber member is thinned for weight reduction has a problem in that its rigidity is likely to be reduced, and high-speed durability and steering stability are reduced.

JP 2013-028195 A

  The present invention has been devised in view of the above circumstances, and provides a pneumatic tire that reduces the tire mass while maintaining steering stability by increasing the rubber hardness of the insulation layer in the buttress region. The main purpose is to do.

  The present invention is a pneumatic tire comprising a carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion, and an inner liner made of an air-impermeable rubber disposed on the tire lumen side of the carcass. In the tire meridian cross section including the tire rotation axis, the sidewall portion includes a thinnest portion having a thickness of 2.0 mm or less, and a buttress region that is an outer region in the tire radial direction of the sidewall portion. Has an insulation layer disposed between the inner liner and the carcass, and the insulation layer is harder than the inner liner and has a JISA hardness of 50 to 98 °. It is characterized by becoming.

  In the pneumatic tire of the present invention, the insulation layer is disposed in at least a part of a region between the ground contact end of the tread portion and the tire maximum width position located on the inner side in the tire radial direction. desirable.

  In the pneumatic tire of the present invention, the insulation layer has an inner end in the tire radial direction, and the inner end of the insulation layer is located on the outer side in the tire radial direction with respect to the tire maximum width position. The distance in the tire radial direction between the end and the tire maximum width position is preferably 2 to 20 mm.

  The pneumatic tire according to the present invention includes a tread reinforcing layer radially outward of the carcass and inside the tread portion, and the insulation layer has an outer end in the tire radial direction, and the outer layer of the insulation layer It is desirable that the end is located on the inner side in the tire axial direction than the outer edge in the tire axial direction of the tread reinforcing layer, and the distance in the tire axial direction between the outer end and the outer edge of the tread reinforcing layer is preferably 2 to 15 mm. .

  In the pneumatic tire of the present invention, the insulation layer is preferably made of rubber having a JISA hardness of 70 to 90 °.

  In the pneumatic tire according to the present invention, the bead portion includes a bead apex made of hard rubber that tapers outward from the bead core in the tire radial direction, and the height of the bead apex from the bead core in the tire radial direction is 20 mm. The following is desirable.

  In the pneumatic tire of the present invention, the bead portion has a clinch rubber disposed on the outer surface side of the carcass and the bead apex, and the clinch rubber is a surface layer portion that comes into contact with the rim when the tire is attached to the rim. The surface layer portion is preferably made of rubber having a JISA hardness of 70 to 90 °.

  In the pneumatic tire of the present invention, it is desirable that the maximum thickness of the clinch rubber is 5 to 15 mm.

  The pneumatic tire of the present invention includes a carcass extending from a tread portion through a sidewall portion to a bead core of the bead portion, and an inner liner made of air-impermeable rubber disposed on the tire lumen side of the carcass. . Moreover, in the tire meridian cross section including the tire rotation axis, the sidewall portion includes the thinnest portion having a thickness of 2.0 mm or less. Thereby, the rubber volume of the sidewall portion is reduced and the tire mass is reduced.

  An insulation layer is disposed between the inner liner and the carcass in the buttress region, which is an outer region in the tire radial direction of the sidewall portion. The insulation layer is harder than the inner liner and is made of rubber having a JISA hardness of 50 to 98 °. Such an insulation layer increases the rigidity of the buttress region that is easily bent during traveling without increasing the tire mass, and thus maintains steering stability.

  As described above, the pneumatic tire of the present invention can reduce tire mass while maintaining steering stability.

It is sectional drawing which shows one Embodiment of the pneumatic tire of this invention. It is an enlarged view of the buttress area | region of FIG. It is sectional drawing of the tire of a load load state. It is an enlarged view of the bead part of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a tire meridian cross-sectional view including a tire rotation axis in a normal state of a pneumatic tire (hereinafter, simply referred to as “tire”) 1 of the present embodiment. The tire 1 of the present embodiment is suitably used as a passenger vehicle tire, for example.

  The “normal state” is a no-load state in which the tire is assembled on a normal rim (not shown) and filled with a normal internal pressure. Hereinafter, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in this normal state.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, “ETRTO” Then "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is the “highest air pressure”, TRA is the table “TIRE LOAD LIMITS AT” The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO.

  The tire 1 according to the present embodiment includes a carcass 6, a tread reinforcing layer 10, and an inner liner 11.

  The carcass 6 has, for example, a toroid shape that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4. The carcass 6 is composed of, for example, one carcass ply 6A in which carcass cords are arranged at an angle of, for example, 80 to 90 ° with respect to the tire equator C. As the carcass cord, for example, an organic fiber cord such as polyester, nylon, rayon, or aramid is suitably employed.

  The carcass ply 6A includes a series of a main body portion 6a straddling between the bead cores 5 and 5, and a turn-back portion 6b connected to both ends thereof and turned around the bead core 5 from the inner side to the outer side in the tire axial direction.

  A bead apex 8 made of hard rubber is disposed between the main body 6a and the folded portion 6b. The bead apex 8 has a substantially triangular cross-section extending from the bead core 5 outward in the tire radial direction. Thereby, the bending rigidity of the bead part 4 and the side wall part 3 is reinforced.

  The height h1 of the bead apex 8 from the bead core 5 in the tire radial direction is preferably 25 mm or less, more preferably 20 mm or less. Such a bead apex 8 reduces the rubber volume of the bead portion 4 and effectively reduces the tire mass. The height h1 of the bead apex 8 is preferably 10 mm or more, more preferably 15 mm or more. Such a bead apex 8 effectively maintains the rigidity of the bead portion 4.

  The bead apex 8 is preferably made of rubber having a JISA hardness of 65 to 95 °, for example. Such a bead apex 8 effectively increases the rigidity of the bead portion 4 and improves steering stability. In this specification, JISA hardness means the hardness by durometer type A measured in the environment of 23 degreeC based on JIS-K6253.

  The tread reinforcing layer 10 is disposed, for example, radially outside the carcass 6 and inside the tread portion 2. The tread reinforcing layer 10 is disposed on substantially the entire area of the tread portion 2.

  The tread reinforcing layer 10 of this embodiment includes a belt layer 7 and a band layer 9. The belt layer 7 is formed of, for example, two belt plies 7A and 7B. In each belt ply 7A, 7B, for example, belt cords are arranged at an angle of 10 to 35 ° with respect to the tire equator C. The belt plies 7A and 7B of the present embodiment are arranged in different directions so that the belt cords cross each other between the plies. Thereby, the rigidity of the tread portion 2 is effectively increased. As the belt cord, for example, a highly elastic organic fiber cord such as rayon or aramid, or a steel cord can be adopted.

  The band layer 9 is disposed, for example, on the outer side in the tire radial direction of the belt layer 7. The band layer 9 of the present embodiment covers substantially the entire area of the belt layer 7. The band layer 9 is formed by, for example, winding a band cord spirally at an angle of 0 to 5 ° with respect to the tire equator C. For the band cord, for example, an organic fiber cord such as nylon, aramid, or PEN is adopted.

  The inner liner 11 is disposed on the tire lumen side of the carcass 6. The inner liner 11 extends, for example, continuously across the pair of bead portions 4 and 4 and forms substantially the entire region of the tire lumen surface 1i. The inner liner 11 is made of air impermeable rubber, for example. As the air-impermeable rubber, for example, a butyl rubber in which 60 to 100 parts by mass of butyl rubber (or a derivative thereof) is blended in 100 parts by mass of the rubber component is suitably employed.

  Each sidewall part 3, 3 of the tire 1 of the present invention includes a thinnest part 13 having a thickness t1 of 2.0 mm or less. Thereby, the rubber volume of the sidewall portion 3 is reduced, and the tire mass is reduced.

  FIG. 2 shows an enlarged view of the buttress area 14 which is an outer area of the sidewall portion 3 in the tire radial direction. As shown in FIG. 2, an insulation layer 20 is disposed between the inner liner 11 and the carcass 6 in the buttress region 14. The insulation layer 20 is disposed along the carcass 6 with a substantially constant thickness.

  The insulation layer 20 is made of rubber that is harder than the inner liner 11 and has a JISA hardness Hi of 50 to 98 °.

  FIG. 3 shows a cross-sectional view of the tire 1 in a loaded state in which the tread portion 2 contacts the road surface G and a normal load is applied. As shown in FIG. 3, the buttress region 14 and the bead portion 4 of the tire 1 are easily bent in a loaded state. The insulation layer 20 as described above effectively increases the rigidity of the buttress region 14 that is easily bent during traveling without increasing the tire mass, and thus maintains steering stability.

  “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” is “Maximum load capacity”, TRA is “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  When the JISA hardness Hi of the insulation layer 20 is less than 50 °, the rigidity of the buttress region may not be increased. When the JISA hardness Hi of the insulation layer 20 is greater than 98 °, ride comfort may be reduced.

  The JISA hardness Hi of the insulation layer 20 is preferably 70 ° or more, more preferably 75 ° or more, preferably 90 ° or less, more preferably 85 ° or less. Such an insulation layer 20 increases the rigidity of the buttress region 14 while maintaining ride comfort.

  As shown in FIG. 2, the insulation layer 20 is disposed in at least a part of a region between the ground contact end Te of the tread portion 2 and the tire maximum width position 15 located on the inner side in the tire radial direction. .

  The contact end Te of the tread portion 2 is a contact position on the outermost side in the tire axial direction when the normal tire 1 is loaded with a normal load and contacted to a plane with a camber angle of 0 degree. The tire maximum width position 15 is a position where the maximum width of the tire is formed.

  The insulation layer 20 has an inner end 20i in the tire radial direction. For example, the inner end 20 i of the insulation layer 20 is preferably located on the outer side in the tire radial direction from the tire maximum width position 15. When the inner end 20i of the insulation layer 20 is located on the inner side in the tire radial direction from the tire maximum width position 15, the tire mass may increase, and the fuel efficiency may decrease.

  The distance L1 in the tire radial direction between the inner end 20i of the insulation layer 20 and the tire maximum width position 15 is preferably 2 mm or more, more preferably 7 mm or more, preferably 20 mm or less, more preferably 15 mm or less. is there. Such an insulation layer 20 effectively increases the rigidity of the buttress region 14 while minimizing an increase in tire mass.

  The insulation layer 20 has an outer end 20o in the tire radial direction. For example, the outer end 20o of the insulation layer 20 is preferably located on the inner side in the tire axial direction of the outer edge 10o of the tread reinforcing layer 10 in the tire axial direction. Thereby, the peeling of the insulation layer 20 starting from the outer end 20o is effectively suppressed, and the durability of the tread portion 2 is improved.

  The distance L2 in the tire axial direction between the outer end 20o of the insulation layer 20 and the outer edge 10o of the tread reinforcing layer 10 is preferably 2 mm or more, more preferably 5 mm or more, preferably 15 mm or less, more preferably 12 mm or less. is there. Such an insulation layer 20 effectively suppresses peeling of the insulation layer 20 starting from the outer end 20o while minimizing an increase in tire mass.

  The thickness t2 of the insulation layer 20 is preferably 0.3 mm or more, more preferably 0.5 mm or more, preferably 1.0 mm or less, more preferably 0.8 mm or less. Such an insulation layer 20 effectively increases the rigidity of the buttress region 14 while minimizing an increase in tire mass.

  As the rubber used for the insulation layer 20, for example, diene rubber, more specifically natural rubber, isoprene rubber, styrene butadiene rubber, chloroprene rubber or acrylonitrile butadiene rubber is preferably used. These various rubbers may be used alone or in combination of two or more.

  FIG. 4 shows an enlarged view of the bead portion 4. As shown in FIG. 4, clinch rubber 23 is disposed on the bead portion 4 on the tire outer surface side of the carcass 6 and the bead apex 8.

  The maximum thickness t3 of the clinch rubber 23 is preferably 5 mm or more, more preferably 8 mm or more, preferably 15 mm or less, more preferably 12 mm or less. Such clinch rubber 23 increases the rigidity of the bead portion 4 while suppressing an increase in tire mass to a minimum.

  The clinch rubber 23 includes a main body portion 24 and a surface layer portion 25 that forms an outer surface of the main body portion 24 and comes into contact with the rim when the tire is attached to the rim. The surface layer portion 25 is preferably formed of rubber harder than the main body portion 24 of the clinch rubber 23. As shown in FIG. 3, such a clinch rubber 23 improves the steering stability by suppressing deformation of the bead portion 4 during traveling, and also effectively damages the surface layer portion 25 due to friction with the rim R. To suppress.

  The JISA hardness Hs of the rubber of the surface layer portion 25 is preferably 70 ° or more, more preferably 75 ° or more, preferably 90 ° or less, more preferably 85 ° or less. Such a surface layer portion 25 may not obtain the above-described effects when the JISA hardness Hs of the surface layer portion 25 is smaller than 70 °. When the JISA hardness Hs of the surface layer portion 25 is greater than 90 °, the surface layer portion 25 may be easily peeled off from the main body portion 24.

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, this invention is not limited to said specific embodiment, It implements by changing into various aspects.

A pneumatic tire of size 195 / 65R15 having the basic structure shown in FIG. As Comparative Examples 1 and 2, a tire in which an insulation layer was not arranged in the buttress area was manufactured. The tire mass and the longitudinal and lateral springs of each tire were measured. The common specifications and test methods for each tire are as follows.
Wearing rim: 15 × 6J
Tire internal pressure: 230kPa

<Tire mass>
The mass per tire was measured. The result is an index with Comparative Example 1 as 100. The smaller the numerical value, the smaller the tire mass and the better the fuel efficiency.

<Vertical spring>
Each test tire was mounted on the rim, and the amount of vertical deflection of the tire was measured when the test tire was brought into contact with a flat surface with a vertical load of 4.24 ± 1.0 kN. A vertical spring constant was approximately obtained by dividing the vertical load of 4.24 kN by the vertical deflection amount. The results are displayed as an index with the longitudinal spring constant of Comparative Example 1 as 100. The smaller the value, the smaller the vertical spring and the better the ride comfort.

<Horizontal spring>
Lateral deflection of the tire when each test tire is mounted on the rim, grounded on a plane with a vertical load of 4.24 ± 1.0 kN, and a lateral load of 0.5 ± 0.5 kN is applied in the tire axial direction The amount was measured. Then, the lateral spring coefficient was approximately obtained by dividing the lateral load of 0.5 kN by the lateral deflection amount. The results are displayed as an index with the lateral spring coefficient of Comparative Example 1 as 100. The larger the value, the larger the lateral spring and the better the steering stability performance.
The test results are shown in Table 1.

  As is clear from Table 1, it was confirmed that the pneumatic tires of the examples reduced the tire mass while maintaining the steering stability.

2 Tread part 3 Side wall part 4 Bead part
5 Bead core 6 Carcass 11 Inner liner 13 Thinnest part 14 Buttress area 20 Insulation layer

Claims (8)

A pneumatic tire comprising a carcass extending from a tread portion through a sidewall portion to a bead core of the bead portion, and an inner liner made of air-impermeable rubber disposed on the tire lumen side of the carcass,
In the tire meridian cross section including the tire rotation axis, the sidewall portion includes a thinnest portion having a thickness of 2.0 mm or less,
An insulation layer is disposed between the inner liner and the carcass in the buttress region, which is an outer region in the tire radial direction of the sidewall portion,
The pneumatic tire is characterized in that the insulation layer is harder than the inner liner and is made of rubber having a JISA hardness of 50 to 98 °.   2. The pneumatic tire according to claim 1, wherein the insulation layer is disposed in at least a part of a region between a ground contact end of the tread portion and a tire maximum width position located on an inner side in the tire radial direction. The insulation layer has an inner end in the tire radial direction,
The inner end of the insulation layer is located on the outer side in the tire radial direction from the tire maximum width position,
The pneumatic tire according to claim 1 or 2, wherein a distance in a tire radial direction between the inner end and the tire maximum width position is 2 to 20 mm. Comprising a tread reinforcing layer on the outside of the carcass in the radial direction and inside the tread portion;
The insulation layer has an outer end in the tire radial direction,
The outer end of the insulation layer is located on the inner side in the tire axial direction than the outer edge in the tire axial direction of the tread reinforcing layer,
The pneumatic tire according to any one of claims 1 to 3, wherein a distance in a tire axial direction between the outer end and the outer edge of the tread reinforcing layer is 2 to 15 mm.   The pneumatic tire according to claim 1, wherein the insulation layer is made of rubber having a JISA hardness of 70 to 90 °. The bead portion includes a bead apex made of a hard rubber tapering out from the bead core outward in the tire radial direction,
The pneumatic tire according to any one of claims 1 to 5, wherein a height of the bead apex in the tire radial direction from the bead core is 20 mm or less. In the bead portion, clinch rubber is disposed on the outer surface side of the tire of the carcass and the bead apex,
The clinch rubber includes a surface layer portion that comes into contact with the rim when the tire is attached to the rim,
The pneumatic tire according to claim 6, wherein the surface layer portion is made of rubber having a JISA hardness of 70 to 90 °.   The pneumatic tire according to claim 7, wherein a maximum thickness of the clinch rubber is 5 to 15 mm.

Images