Pneumatic radial tire for passenger vehicle

Abstract

Provided is a pneumatic radial tire for a passenger vehicle, in which the cross-sectional width (SW) of the tire and the outer diameter (OD) of the tire satisfy a predetermined relationship, and a layer is provided only in one half of the tire in the width direction of the tire, said layer being disposed on the outside of a belt in the radial direction of the tire and covering at least the end of the belt.

Description

Technical Field

[0001] The present disclosure relates to a pneumatic radial tire for a passenger vehicle. Background Art

[0002] As a pneumatic radial tire for passenger cars that improves fuel efficiency, the applicant has proposed a narrow-width, large-diameter pneumatic radial tire for passenger cars having a predetermined relationship between the tire's section width SW and outer diameter OD (eg, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: WO 2011 / 135774 A1 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In recent years, the development of personal motor vehicles has progressed, and among the above-mentioned narrow-width and large-diameter pneumatic radial tires for passenger cars, it is considered that pneumatic radial tires for passenger cars having a particularly small section width SW will be used.

[0008] However, when the cross-sectional width SW of the tire is small, especially when a large camber angle is given or the camber angle increases due to a change in the camber angle, there is a risk that the shape of the ground contact patch of the tire will deteriorate and the driving performance will decrease. In addition, the above-mentioned narrow-width and large-diameter pneumatic radial tires for passenger cars are often used at high internal pressures, and in this case, the problem of deterioration in the shape of the ground contact patch becomes particularly significant.

[0009] Solutions for solving problems

[0010] Therefore, an object of the present disclosure is to provide a pneumatic radial tire for a passenger vehicle, which can improve the shape of a ground contact patch of the pneumatic radial tire for a passenger vehicle and control the degradation of driving performance.

[0011] The main points of the present invention are as follows:

[0012] (1) A pneumatic radial tire for a passenger vehicle, comprising

[0013] a pair of bead portions;

[0014] a carcass composed of one or more carcass plies spanning in a toroidal manner between the pair of bead portions; and

[0015] The belt portion is composed of one or more belt layers arranged on the outer side of the crown portion of the carcass in the radial direction of the tire, wherein:

[0016] The cross-sectional width SW of the tire is less than 165 (mm),

[0017] The ratio of the cross-sectional width SW of the tire to the outer diameter OD of the tire is 0.26 or less, or the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) of the tire satisfy the relational expression: OD (mm) ≥ -0.0187 × SW (mm) 2 +9.15×SW(mm)-380(mm), and

[0018] A layer that is arranged on the tire radial direction outer side of the belt portion and covers at least an end portion of the belt portion is provided only in one tire width direction half portion.

[0019] As used herein, the term "rim" refers to a standard rim of an applicable size described or that may be described in the future in an industrial standard effective for a region where tires are produced and used (such as the JATMA Yearbook of JATMA (Japan Automobile Tire Manufacturers Association) in Japan, the standard manual of ETRTO (European Tire and Rim Technical Organization) in Europe, and the yearbook of TRA (Tire and Rim Association) in the United States) (that is, the "rim" of the above-mentioned "wheel" includes current sizes as well as sizes to be described in the future in the above-mentioned industrial standards. An example of a "size to be described in the future" may be a size listed as "future development" in the 2013 edition of ETRTO), however, for sizes not listed in these industrial standards, the term "rim" refers to a rim having a width corresponding to the bead width of the tire.

[0020] In addition, the term "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel of applicable size and ply grade as described in the above-mentioned JATMA Yearbook and other industrial standards. In the case of a size not listed in the above-mentioned industrial standards, the term "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is installed.

[0021] Furthermore, the term "maximum load" refers to a load corresponding to the above-mentioned maximum load capacity.

[0022] It will be noted that when the number of cords per unit width of the cap layer described below is not constant, the number of cords per unit width of the cap layer shall mean an average value of the number of cords per unit width in one tire width direction half and the other tire width direction half.

[0023] In addition, when the tire has two or more cover layers, the "number of cords per unit width of the cover layer" should be calculated by dividing the total number of cords of all layers in the tire width direction cross section by the total width of all cover layers in the tire width direction and converting the result into units (cords / 50 mm).

[0024] Effects of the Invention

[0025] According to the present disclosure, it is possible to provide a pneumatic radial tire for a passenger vehicle that can improve the shape of a ground contact patch of the pneumatic radial tire for a passenger vehicle and control a decrease in driving performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the attached figure:

[0027] Figure 1 is a schematic diagram illustrating the cross-sectional width SW and the outer diameter OD of a tire;

[0028] Figure 2 is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger vehicle according to one embodiment of the present disclosure;

[0029] Figure 3 is a schematic diagram for explaining the change in shape of the ground contact surface;

[0030] Figure 4 is a diagram for explaining the configuration of an RFID; and

[0031] Figure 5 1 is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger vehicle according to a modification. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0033] Figure 1 It is a schematic diagram illustrating the cross-sectional width SW and the outer diameter OD of the tire.

[0034] A pneumatic radial tire for a passenger vehicle (hereinafter, simply referred to as a "tire") according to one embodiment of the present disclosure has a tire section width SW of less than 165 mm, and a ratio SW / OD of the tire section width SW to the outer diameter OD is 0.26 or less, and thus has a narrow width and large diameter shape. By making the tire section width SW narrower relative to the outer diameter OD of the tire, air impedance can be reduced, and by making the outer diameter OD of the tire larger relative to the tire section width SW, deformation of the tread rubber in the area near the contact surface of the tire is controlled and rolling impedance can be reduced, and by these means, the fuel efficiency of the tire can be improved. The ratio SW / OD is preferably 0.25 or less, and more preferably 0.24 or less.

[0035] The above ratio is preferably satisfied when the tire internal pressure is 200 kPa or more, more preferably satisfied when the tire internal pressure is 220 kPa or more, and even more preferably satisfied when the tire internal pressure is 280 kPa or more. This is because the rolling resistance can be reduced. On the other hand, it is preferred that the above ratio is satisfied when the tire internal pressure is 350 kPa or less. This is because the ride comfort can be improved.

[0036] Here, the section width SW of the tire is preferably 105 to 145 mm, and more preferably 115 to 135 mm.

[0037] Furthermore, when the section width SW and the outer diameter OD of the tire satisfy the above ratio, the aspect ratio of the tire is preferably 45 to 70, and more preferably 45 to 65.

[0038] The specific tire size is not particularly limited, but can be, for example, 105 / 50R16, 115 / 50R17, 125 / 55R20, 125 / 60R18, 125 / 65R19, 135 / 45R21, 135 / 55R20, 135 / 60R17, 135 / 60R18, 135 / 60R19, 135 / 65R19, 145 / 45R21, 145 / 55R2 Any size in 0, 145 / 60R16, 145 / 60R17, 145 / 60R18, 145 / 60R19, 145 / 65R19, 155 / 45R18, 155 / 45R21, 155 / 55R18, 155 / 55R19, 155 / 55R21, 155 / 60R17, 155 / 65R18, 155 / 70R17, 155 / 70R19.

[0039] Alternatively, the section width SW of the tire is less than 165 mm, and the section width SW (mm) and the outer diameter OD (mm) of the tire satisfy the relational expression:

[0040] OD(mm)≥-0.0187×SW(mm) 2 +9.15×SW(mm)-380,

[0041] Therefore, the tire has a shape of narrow width and large diameter.

[0042] By satisfying the above relational expressions, air resistance and rolling resistance can be reduced, thereby improving the fuel efficiency of the tire.

[0043] In the third aspect, regarding the cross-sectional width SW and the outer diameter OD of the tire, when the above relational expression is satisfied, the ratio SW / OD is preferably 0.26 or less, more preferably 0.25 or less, and even more preferably 0.24 or less. This is because the fuel efficiency of the tire can be further improved.

[0044] The above relational expression and ratio are preferably satisfied when the tire internal pressure is 200 kPa or more, more preferably satisfied when the tire internal pressure is 220 kPa or more, and even more preferably satisfied when the tire internal pressure is 280 kPa or more. This is because the rolling resistance can be reduced. On the other hand, it is preferred that the above relational expression and ratio are satisfied when the tire internal pressure is 350 kPa or less. This is because the ride comfort can be improved.

[0045] Here, the section width SW of the tire is preferably 105 to 145 mm, and more preferably 115 to 135 mm.

[0046] Furthermore, when the section width SW and the outer diameter OD of the tire satisfy the above relationship, the aspect ratio of the tire is preferably 45 to 70, and more preferably 45 to 65.

[0047] The specific tire size is not particularly limited, but can be, for example, 105 / 50R16, 115 / 50R17, 125 / 55R20, 125 / 60R18, 125 / 65R19, 135 / 45R21, 135 / 55R20, 135 / 60R17, 135 / 60R18, 135 / 60R19, 135 / 65R19, 145 / 45R21, 145 / 55R2 Any size in 0, 145 / 60R16, 145 / 60R17, 145 / 60R18, 145 / 60R19, 145 / 65R19, 155 / 45R18, 155 / 45R21, 155 / 55R18, 155 / 55R19, 155 / 55R21, 155 / 60R17, 155 / 65R18, 155 / 70R17, 155 / 70R19.

[0048] The tire of this embodiment is a pneumatic radial tire for passenger cars. The tire is particularly suitable for use as a tire for a personal motor vehicle. The tire can be installed on a vehicle with a relatively large camber angle (e.g., 10° or more).

[0049] Figure 2 1 is a cross-sectional view in the tire width direction of a pneumatic radial tire for a passenger vehicle according to one embodiment of the present disclosure. Figure 2 The figure shows a cross-sectional view of a tire in its reference condition, with the tire mounted on a rim, filled to a specified internal pressure and without a load. Figure 2 As shown, the tire 1 includes a carcass 3, which is composed of a cord layer made of radially arranged cords spanning in a ring shape between a pair of bead portions 2. In addition, in the example shown, the tire 1 includes a belt portion 4 composed of two belt layers 4a and 4b and a tread 5 in sequence on the outer side of the carcass 3 in the tire radial direction.

[0050] In this example, a bead core 2a is embedded in each bead portion 2. In the present disclosure, the cross-sectional shape and material of the bead core 2a are not particularly limited, and can be made to have a structure commonly used in pneumatic radial tires for passenger cars. In the present disclosure, the bead core 2a can be divided into a plurality of small bead cores. Alternatively, in the present disclosure, the bead portion 2 can be constructed without a bead core 2a.

[0051] In the example shown, the tire 1 has a bead filler 2b having a substantially triangular cross section outside the bead core 2a in the tire radial direction. The cross-sectional shape of the bead filler 2b is not limited to this example, and the material is also not limited to this example. Alternatively, the tire can be lightweighted by omitting the bead filler 2b.

[0052] In this embodiment, the tire 1 may also have a rim protection portion. In addition, in this embodiment, the bead portion 2 may also have additional components, such as a rubber layer or a cord layer for reinforcement purposes. These additional components may be arranged at various positions relative to the carcass 3 and the bead filler 2b.

[0053] exist Figure 2 In the example shown, the carcass 3 is composed of a single carcass ply. On the other hand, in the present disclosure, the number of carcass plies is not particularly limited and may be two or more layers. Figure 2In the example shown, the carcass 3 has a carcass main body portion 3a spanning between the pair of bead portions 2 in a ring shape and a carcass folded back portion 3b folded back from the carcass main body portion 3a around the bead core 2a. On the other hand, in the present disclosure, the carcass folded back portion 3b may be wound around the bead core 2a, or may be sandwiched between a plurality of separate small bead cores. As shown in the figure, it is preferred that the end 3c of the carcass folded back portion in one tire width direction half (right side in the figure) is located on the tire radial inner side of the end 3c of the carcass folded back portion in the other tire width direction half (left side in the figure). On the other hand, the end 3c of the carcass folded back portion in one tire width direction half (right side in the figure) may be located on the tire radial outer side of the end 3c of the carcass folded back portion 3b in the other tire width direction half (left side in the figure), or they may be at the same height. In the present example, the end 3c of the carcass folded back portion 3b is located on the tire radial outer side of the tire radial outer end of the bead filler 2b, and is located on the tire radial inner side of the tire maximum width position. This makes it possible to lightweight the tire while maintaining the rigidity of the sidewall portion. On the other hand, in the present disclosure, the end 3c of the carcass folded portion 3b may be located on the tire radially inner side of the tire radially outer end of the bead filler 2b, or it may be located on the tire radially outer side of the tire maximum width position. Alternatively, the carcass may have an encapsulation structure in which the end 3c of the carcass folded portion 3b is located on the tire width direction inner side of the end of the belt portion 4 (e.g., the end of the belt layer 4b), so that the end 3c of the carcass folded portion 3b is located between the carcass main body portion 2a and the belt portion 4 in the tire radial direction. In addition, for example, in one tire width direction half, the end 3c of the carcass folded portion 3b may be located on the tire radially outer side of the tire radially outer end of the bead filler 2b and on the tire radially inner side of the tire maximum width position, and in the other tire width direction half, the end 3c of the carcass folded portion 3b may be located on the tire radially outer side of the tire maximum width position. In addition, when the carcass 3 is composed of a plurality of carcass plies, the position of the end 3c of the carcass folded portion 3b (for example, the position in the tire radial direction) may be the same or different between the carcass plies. There is no particular limitation on the number of carcass cords per unit width in the carcass 3, but, for example, it may be in the range of 20 to 60 cords / 50 mm. In addition, the carcass cord may adopt various structures. For example, in the tire radial direction, the carcass maximum width position may be closer to the bead portion 2 side or to the tread portion 5 side. For example, the carcass maximum width position may be set within the range of 50% to 90% of the cross-sectional height of the tire from the bead baseline to the tire radial outside. The above-mentioned "meridian configuration" refers to a configuration in which the carcass cords extend at an angle of 85° or more and preferably 90° relative to the tire circumference.

[0054] In the present embodiment, the tire preferably has one or more inclined belt layers made of rubber-coated cord layers extending at an angle relative to the tire circumferential direction, and two layers are most preferred in terms of the balance between achieving lightweight and controlling the distortion of the shape of the contact patch. From the perspective of lightweight, the belt layer can be made into one layer, and from the perspective of controlling the distortion of the shape of the contact patch, the belt layer can be made into three or more layers. Figure 2 In the example shown, of the two belt layers 4a and 4b, the tire width direction width of the belt layer 4b located on the outer side of the tire radial direction is smaller than the tire width direction width of the belt layer 4a located on the inner side of the tire radial direction. On the other hand, the tire width direction width of the belt layer 4b located on the outer side of the tire radial direction may be greater than or equal to the tire width direction width of the belt layer 4a located on the inner side of the tire radial direction. The tire width direction width of the belt layer having the maximum width in the tire width direction (in the example shown, the belt layer 4a) is preferably 90% to 115% of the ground contact width, and particularly preferably 100% to 105% of the ground contact width. It will be noted that the "ground contact width" refers to the distance between the ground contact ends E in the tire width direction. The "ground contact ends" refer to the two ends of the tire ground contact surface in the tire width direction when the tire is mounted on the rim, filled with a specified internal pressure and loaded with a maximum load.

[0055] In the present embodiment, as the belt cords of the belt layers 4a, 4b, metal cords, particularly steel cords, are most preferably used, but non-metal cords such as organic fiber cords (e.g., Kevlar (registered trademark) etc.) may also be used. Steel cords are mainly made of steel, and may also contain various trace elements such as carbon, manganese, silicon, phosphorus, sulfur, copper and chromium. In the present embodiment, the belt cords of the belt layers 4a, 4b may be monofilament cords, cords made of a plurality of filaments arranged in parallel, or cords made of a plurality of filaments twisted together. Various twisting structures may be used, and the cross-sectional structure, twisting pitch, twisting direction and distance between adjacent filaments may also be changed. In addition, cords made of twisted filaments of different materials may also be used, and there is no particular limitation on the cross-sectional structure, and various twisting structures such as single twist, layer twist and multi-twist may be used.

[0056] In the present embodiment, the inclination angle of the belt cords in the belt layers 4a, 4b relative to the tire circumferential direction is preferably 10° or more. In the present embodiment, the inclination angle of the belt cords in the belt layers 4a, 4b relative to the tire circumferential direction is preferably a higher angle, specifically 20° or more and preferably 35° or more, particularly in the range of 55° to 85° relative to the tire circumferential direction. This is because, by making the inclination angle 20° or more (preferably 35° or more), the rigidity in the tire width direction can be increased, and the steering stability performance, especially the steering stability performance during cornering, can be improved. In addition, this is because the rolling resistance is reduced by reducing the shear deformation of the interlayer rubber.

[0057] In the example shown, the tread rubber constituting the tread 5 is composed of a single layer. On the other hand, in the present embodiment, the tread rubber constituting the tread 5 can be formed by laminating a plurality of rubber layers in the tire radial direction. The plurality of rubber layers may have different loss tangents, moduli, hardness, glass transition temperatures, materials, etc. In addition, the thickness ratio of the plurality of rubber layers in the tire radial direction may vary in the tire width direction, and the bottom of the circumferential main groove, etc. may also be made of a rubber layer different from the peripheral area. In addition, the tread rubber constituting the tread 5 may be formed by a plurality of rubber layers different in the tire width direction. The plurality of rubber layers may have different loss tangents, moduli, hardness, glass transition temperatures, materials, etc. In addition, the width ratio of the plurality of rubber layers in the tire width direction may vary in the tire radial direction, and only a limited area (such as only the area near the circumferential main groove, only the area near the ground contact end, only the shoulder land portion, or only the central land portion, etc.) may have a rubber layer different from the peripheral area.

[0058] The tire 1 of this embodiment has an inner liner 8 on the inner surface 7 of the tire (referred to as the inner surface 7 of the tire for short), and the thickness of the inner liner 8 is preferably about 1.5 mm to 2.8 mm. This is because it can effectively reduce the noise inside the vehicle between 80 and 100 Hz. The air permeability coefficient of the rubber composition constituting the inner liner 8 is preferably 1.0×10 -14 cc·cm / (cm 2 ·s·cmHg) or greater and 6.5×10 -10 cc·cm / (cm 2 ·s·cmHg) or less.

[0059] Here, it is preferred that the negative ratio of the tread surface is larger in one half in the tire width direction than in the other half in the tire width direction. "Tread surface" refers to the outer surface in contact with the road surface around the entire circumference of the tire when the tire is mounted on the rim, filled with a specified internal pressure and rolling under maximum load. In addition, the "negative ratio" refers to the ratio of the total area of ​​the grooves having a width (opening width) of 2 mm or more to the total area of ​​the tread surface. This is because the driving performance of the tire can be further improved by relatively reducing the rigidity of the tread portion in one half in the tire width direction, thereby further improving the shape of the contact surface described below. It will be noted that in the case where the tire size is a narrow width and large diameter as described above, since the narrow width ensures high drainage performance, only one circumferential main groove extending along the tire circumference is provided in one half in the tire width direction, so that the negative ratio in one half in the tire width direction can be greater than the negative ratio in the other half in the tire width direction.

[0060] like Figure 2 As shown, the tire includes a layer 9 only in one half in the tire width direction, and the layer 9 is arranged on the tire radial outside of the belt portion 4 and covers at least the end of the belt portion 4. In addition, the tire includes one or more (one in the illustrated example) cover layers 8, which are located on the tire radial outside of the belt portion 4 and on the tire radial inside of the layer 9.

[0061] The cover layer 8 is composed of a strip-shaped member, which is composed of rubber-coated cords arranged in approximately parallel and spirally wound in the tire circumferential direction. In the example shown, the tire width direction width of the cover layer 8 is greater than the tire width direction width of the belt portion 4. As for the cords of the cover layer 8, for example, organic fiber cords can be used. As shown in the figure, it is preferred that the number of cords per unit width of the cover layer 8 is larger in one tire width direction half than in the other tire width direction half. In this example, the number of cords per unit width of the cover layer 8 in one tire width direction half is constant, and the number of cords per unit width of the cover layer 8 in the other tire width direction half is also constant. On the other hand, for example, the number of cords per unit width can also be constructed to gradually decrease from the tire width direction outer end of the cover layer 8 in one tire width direction half to the tire width direction outer end of the cover layer 8 in the other tire width direction half.

[0062] Furthermore, it is also preferred that the tire width direction width of the cap layer 9 is larger in one tire width direction half than in the other tire width direction half. In this case, the number of cords per unit width of the cap layer 8 in one tire width direction half may be the same as the number of cords per unit width of the cap layer 8 in the other tire width direction half.

[0063] Layer 9 is composed of a strip-shaped member composed of rubber-coated cords arranged approximately in parallel and spirally wound in the tire circumferential direction. In the example shown, layer 9 covers the end of the belt portion 4 in one tire width direction half. More specifically, the tire width direction outer end of layer 9 is located on the tire width direction outer side of the tire width direction outer end of the belt layer 4a, and the tire width direction inner end of layer 9 is located on the tire width direction inner side of the tire width direction inner end of the belt layer 4b. As for the cord of layer 9, for example, an organic fiber cord can be used.

[0064] The effects of the pneumatic radial tire for passenger vehicles according to the present embodiment will be described below. The effects when "one tire widthwise half" is located inside when the tire is mounted on a vehicle (when "the other tire widthwise half" is located outside when the tire is mounted on a vehicle) will be described below.

[0065] The pneumatic radial tire for a passenger car in the present embodiment is a narrow width large diameter tire having a cross-sectional width SW of less than 165 mm among narrow width large diameter tires satisfying the above relationship expression between the cross-sectional width SW and the outer diameter of the tire. According to this tire, air resistance can be particularly reduced, and rolling resistance can also be reduced, so that the fuel efficiency of the tire can be improved.

[0066] On the other hand, as in Figure 3 As schematically shown on the left side of the arrow in , in such a tire, when a large camber angle is applied or the camber angle becomes large during cornering, the shape of the contact patch becomes too narrow, the shape of the contact patch deteriorates, and there is a risk that driving performance such as steering stability will deteriorate. Although not limited to any particular case, this problem becomes particularly significant when used at a high internal pressure.

[0067] In response to this, the tire in this embodiment has a layer 9 arranged on the tire radially outer side of the belt portion 4 in only one half in the tire width direction (the inner side when the tire is mounted on the vehicle). This makes the rigidity of the tread portion located on the outer side when the tire is mounted on the vehicle relatively smaller than the rigidity of the tread portion located on the inner side when the tire is mounted on the vehicle, making it easier to extend the ground contact length. Figure 3 As schematically shown on the right side of the arrow in , when a large camber angle is applied, this prevents the shape of the contact patch from becoming too narrow and long, and can control degradation of the shape of the contact patch.

[0068] Therefore, according to the pneumatic radial tire for a passenger vehicle in the present embodiment, it is possible to improve the shape of the ground contact patch and suppress the degradation of the drivability.

[0069] Furthermore, compared with the case where the layer 9 is provided in the tire width direction half portions on both sides, the tire can be made lighter and the rolling resistance can be further reduced.

[0070] Here, it is preferred that one or more cover layers 8 are further provided on the tire radially outer side of the belt portion 4 and the tire radially inner side of the layer 9, and the number of cords per unit width of the cover layer 8 is larger in one tire width direction half than in the other tire width direction half. When "one tire width direction half" is set to the inner side when the tire is mounted on the vehicle, this configuration makes the rigidity of the tread portion located on the outer side when the tire is mounted on the vehicle even more relatively smaller than the rigidity of the tread portion located on the inner side when the tire is mounted on the vehicle, making it easier to extend the ground contact length and further suppressing the deterioration of the shape of the ground contact surface.

[0071] For the same reason, it is also preferred that the tire width direction width of the cap layer 8 is larger in one tire width direction half than in the other tire width direction half.

[0072] Furthermore, it is preferred that the carcass 3 is composed of a carcass main body portion 3a spanning between the pair of bead portions 2 in an annular shape and a carcass folded back portion 3b folded back from the carcass main body portion 3a around a bead core 2a buried in the bead portion 2, and that the end of the carcass folded back portion 3b in one tire width direction half is located radially inward of the end of the carcass folded back portion 3b in the other tire width direction half. When "one tire width direction half" is set to the inside when the tire is mounted on a vehicle, this construction can effectively improve the driving performance by increasing the rigidity of the tire located on the outside when the tire is mounted on a vehicle, which greatly contributes to the driving performance. It will be noted that the position of the end of the carcass folded back portion 3b does not significantly contribute to the shape of the above-mentioned ground contact surface, so it does not hinder the above-mentioned improvement effect on the shape of the ground contact surface.

[0073] In addition, if Figure 5 As shown, the distance in the tire radial direction between a straight line m1 passing through a point on the tread surface at the tire equatorial plane and parallel to the tire width direction and a straight line m2 passing through the ground contact end E and parallel to the tire width direction is defined as the drop height L. CR When the tread width of the tire is defined as TW, the ratio L is preferably CR / TW is greater than 0.045. This allows the crown shape to be relatively round, and thereby the shape of the ground contact patch can be made rounder, with the ground contact length in the shoulder portion being shorter than the ground contact length in the center portion. This prevents the shape of the ground contact patch from becoming too narrow when the camber angle changes, and further controls the degradation of the shape of the ground contact patch. "Ground contact end" refers to the two ends of the ground contact patch (the portion in contact with the road surface) of the tire when the tire is mounted on the rim, filled with a specified internal pressure, and loaded with a maximum load. "Tread width" refers to the distance between the ground contact ends of the tire when the tire is mounted on the rim, filled with a specified internal pressure, and unloaded.

[0074] <Tire and rim assembly>

[0075] Here, a tire and rim assembly is formed by mounting the above-mentioned pneumatic radial tire for passenger vehicles on a rim. According to this tire and rim assembly, the same effects as those explained for the above-mentioned pneumatic radial tire for passenger vehicles can be obtained. At this time, the internal pressure of the tire and rim assembly is preferably 200 kPa or more, more preferably 220 kPa or more, and even more preferably 280 kPa or more. This is because, by increasing the internal pressure, rolling resistance can be further reduced. On the other hand, the internal pressure of the tire and rim assembly is preferably 350 kPa or less because this improves ride comfort.

[0076] <How to use pneumatic radial tires for passenger cars>

[0077] The method for using the pneumatic radial tire for a passenger car uses the above-mentioned pneumatic radial tire for a passenger car. According to the method for using the pneumatic radial tire for a passenger car, the same effects as those described above for the pneumatic radial tire for a passenger car can be obtained. At this time, it is preferred to use the pneumatic radial tire for a passenger car when the internal pressure is 200 kPa or more, and it is even more preferred to use the pneumatic radial tire for a passenger car when the internal pressure is 220 kPa or more, and it is even more preferred to use the pneumatic radial tire for a passenger car when the internal pressure is 280 kPa or more. This is because the rolling resistance can be further reduced by increasing the internal pressure. On the other hand, it is preferred to use the pneumatic radial tire for a passenger car when the internal pressure is 350 kPa or less because this improves the ride comfort.

[0078] <Example of Communication Device>

[0079] Figure 4 A tire widthwise half including the layers is shown.

[0080] like Figure 4As shown, the tire may include an RF tag as a communication device 50. The RF tag has an IC chip and an antenna. For example, the RF tag can be configured by being sandwiched between multiple components of the same type or different types constituting the tire. In this way, it is easier to attach the RF tag when producing the tire, and the productivity of the tire with the RF tag can be improved. In this example, the RF tag can be configured between, for example, a bead filler and other components adjacent to the bead filler. The RF tag can be buried in any component constituting the tire. In this way, compared with configuring the RF tag by being sandwiched between multiple components constituting the tire, the load on the RF tag can be reduced, thereby improving the durability of the RF tag. In this example, the RF tag can be buried in rubber components such as tread rubber and sidewall rubber. It is preferred that the RF tag is not configured at a position that is a boundary between components having different levels of rigidity in the peripheral length direction, and the peripheral length direction is a direction along the outer surface of the tire when viewed in a tire width direction section. In this way, the RF tag is not configured at a position where the skew is likely to be concentrated based on the rigidity step difference. This reduces the load on the RF tag, thereby improving the durability of the RF tag. In this example, it is preferred that the RF tag is not arranged at a position that is a boundary between the edge of the carcass and a member adjacent to the carcass edge (e.g., sidewall rubber, etc.) when viewed in a cross section in the tire width direction, for example. The number of RF tags is not limited. The tire may have only one RF tag, or it may have two or more RF tags. Here, the RF tag is explained as an example of a communication device, but a communication device other than an RF tag may also be used.

[0081] The RF tag can be configured in, for example, the tread portion of the tire. In this way, the RF tag will not be damaged by the side cut of the tire. The RF tag can be configured in, for example, the center of the tread in the tire width direction. The center of the tread is a position in the tread portion where distortion is less likely to be concentrated. In this way, the load applied to the RF tag can be reduced, thereby improving the durability of the RF tag. This also makes it possible to prevent differences in communication with the RF tag from both outer sides of the tire in the tire width direction. In this example, in the tire width direction, the RF tag can be configured within, for example, 1 / 2 of the tread width centered on the tire equatorial plane. In the tire width direction, the RF tag can be configured at, for example, the end of the tread. If the position of the reader that communicates with the RF tag is predetermined, the RF tag can be configured at, for example, the end of the tread on a side close to the reader. In this example, in the tire width direction, the RF tag can be configured within, for example, 1 / 4 of the tread width with the tread end as the outer end.

[0082] The RF tag can be configured on the tire inner cavity side of a carcass including, for example, one or more carcass plies spanning between the bead portions. In this way, the RF tag becomes less likely to be damaged by external impacts of the tire, or less likely to be damaged by, for example, side cuts or nail punctures. As an example, the RF tag can be configured to be in close contact with the surface of the carcass facing the tire inner cavity. As another example, when there is another component on the tire inner cavity side of the carcass, the RF tag can be configured between the carcass and the other component located on the tire inner cavity side of the carcass. The other component located on the tire inner cavity side of the carcass is, for example, an inner liner forming the inner surface of the tire. As another example, the RF tag can be attached to the inner surface of the tire facing the tire inner cavity. By attaching the RF tag to the inner surface of the tire, it is easy to attach the RF tag to the tire, and it is also easy to check and replace the RF tag. In other words, the convenience of attachment and maintenance of the RF tag can be improved. In addition, by attaching the RF tag to the inner surface of the tire, the RF tag can be prevented from becoming the core of the tire failure compared to the structure in which the RF tag is buried inside the tire. Furthermore, when the carcass has a plurality of carcass plies and there is a position where the plurality of carcass plies overlap, the RF tag may be arranged between the overlapping carcass plies.

[0083] For example, the RF tag can be configured in the tread portion of the tire on the radially outer side of the belt portion, the belt portion including one or more belt plies. As an example, the RF tag can be configured to be in close contact with the belt portion on the radially outer side of the tire relative to the belt portion. In addition, as another example, when a reinforcing belt layer is provided, the RF tag can be configured to be in close contact with the reinforcing belt layer on the radially outer side of the tire relative to the reinforcing belt layer. In addition, as another example, the RF tag can be buried in the tread rubber on the radially outer side of the belt portion. By arranging the RF tag on the outer side of the belt portion in the tread portion of the tire, the communication with the RF tag from the radially outer side of the tire of the tire is less likely to be interfered by the belt portion. Therefore, the communication with the RF tag from the radially outer side of the tire of the tire can be improved. In addition, the RF tag can be configured in the tread portion of the tire, for example, on the radially inner side of the belt portion. In this way, the radially outer side of the RF tag is covered by the belt portion, so the RF tag becomes less likely to be damaged by the impact from the tread surface or by nail puncture. As an example in this regard, the RF tag can be arranged in the tread portion of the tire between the belt portion and the carcass located radially inside the belt portion. In addition, when the belt portion has a plurality of belt plies, the RF tag can be arranged in the tread portion of the tire between any two belt plies. According to this configuration, the radially outer side of the RF tag is covered by one or more belt plies, so the RF tag becomes less likely to be damaged by impact or nail puncture from the tread surface.

[0084] The RF tag can be configured at a position such as in the sidewall portion or bead portion of the tire. For example, the RF tag can be configured on the sidewall portion or bead portion of the side, such as close to a reader that can communicate with the RF tag. This improves the communication between the RF tag and the reader. As an example, the RF tag can be configured between the carcass and the sidewall rubber or between the tread rubber and the sidewall rubber. The RF tag can be configured in the tire radial direction, for example, between the tire maximum width position and the tread surface position. Through this construction, compared with the construction in which the RF tag is configured on the tire radial inner side of the tire maximum width position, the communication with the RF tag from the tire radial outer side of the tire can be improved. The RF tag can be configured on the tire radial inner side of the tire maximum width position, for example. Through this construction, the RF tag is configured near the bead portion with high rigidity. This reduces the load applied to the RF tag, thereby improving the durability of the RF tag. As an example, the RF tag can be configured in a position adjacent to the bead core in the tire radial direction or the tire width direction. Skew is less likely to be concentrated near the bead core, which reduces the load on the RF tag, thereby improving the durability of the RF tag. In particular, it is preferred that the RF tag is disposed radially inward of the tire at the maximum width position of the tire and radially outward of the bead core of the bead portion. With this configuration, the durability of the RF tag can be improved, and the communication between the RF tag and the reader is less likely to be interfered by the bead core, thereby improving the communication performance of the RF tag. In addition, when the sidewall rubber is composed of a plurality of rubber members of the same or different types adjacent to each other in the tire radial direction, the RF tag can be configured to be sandwiched between the plurality of rubber members constituting the sidewall rubber.

[0085] The RF tag can be configured to be sandwiched between the bead filler and the member adjacent to the filling filler, for example. According to this configuration, the RF tag can be placed at a position where strain is less likely to be concentrated due to the disposal of the bead filler. This reduces the load applied to the RF tag, thereby improving the durability of the RF tag. The RF tag can be configured between the bead filler and the carcass, for example. The part of the carcass that sandwiches the RF tag between the carcass and the bead filler can be located outside the tire width direction relative to the bead filler, or inside the tire width direction relative to the bead filler. If the part of the carcass that sandwiches the RF tag between the carcass and the bead filler is located outside the tire width direction relative to the bead filler, the load applied to the RF tag due to the impact or damage from the tire width direction outside of the tire can be even more reduced, thereby improving the durability of the RF tag. In addition, the bead filler can have a portion adjacent to the sidewall rubber configuration. In this case, the RF tag can be configured to be sandwiched between the bead filler and the sidewall rubber. In addition, the bead filler can also have a portion adjacent to the rubber bead chafer configuration. In this case, the RF tag can be configured to be sandwiched between the bead filler and the rubber bead chafer.

[0086] The RF tag can be configured to be, for example, sandwiched between the rubber bead packer and the sidewall rubber. According to this construction, the RF tag can be placed at a position where strain is less likely to concentrate due to the placement of the rubber bead packer. This reduces the load applied to the RF tag, thereby improving the durability of the RF tag. The RF tag can be configured to be, for example, sandwiched between the rubber bead packer and the carcass. According to this construction, the load applied to the RF tag due to impact and damage from the rim can be reduced. Therefore, the durability of the RF tag can be improved.

[0087] The RF tag can be configured to be, for example, sandwiched between a wire bead filler and another member adjacent to the wire bead filler on the outside or inside of the wire bead filler in the tire width direction. According to this configuration, the position of the RF tag is less likely to change when the tire is deformed. This reduces the load applied to the RF tag when the tire is deformed, thereby improving the durability of the RF tag. Another member adjacent to the wire bead filler on the inside or outside of the tire width direction may be a rubber member, such as a rubber bead filler. In addition, another member adjacent to the wire bead filler on the inside or outside of the tire width direction may be a carcass.

[0088] A belt reinforcement layer may be provided on the tire radially outer side of the belt portion. For example, the belt reinforcement layer may be made by continuously spirally winding a cord made of polyethylene terephthalate around the tire in the tire circumferential direction. -2 N / tex or more tension applied adhesive treatment to make the cord, the elastic modulus under 29.4N load measured at 160°C can be 2.5mN / dtex% or more. In addition, the belt reinforcement layer can be configured to cover the entire belt portion, or it can be configured to cover only the two ends of the belt portion. In addition, the winding density per unit width of the belt reinforcement layer can be changed according to the position in the width direction. According to this configuration, road noise and flat spots can be reduced without reducing high-speed durability.

[0089] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. For example, in the above examples, we have shown a case with a single cover layer, but in order to make the tire lightweight, it is also possible to have a structure without a cover layer.

[0090] Reference numerals list

[0091] 1 Pneumatic radial tires for passenger cars (tire)

[0092] 2 Bead section

[0093] 2a Bead core

[0094] 2b Bead filler

[0095] 3 Carcass

[0096] 4 Belt

[0097] 4a, 4b belt layer

[0098] 5 Tread

[0099] 6 Tire inner surface

[0100] 7 Lining

[0101] 8 Covering layer

[0102] 9th floor

[0103] 50 communication devices

[0104] CL Tire equatorial plane

Claims

1. A pneumatic radial tire for a passenger vehicle, comprising: a pair of bead portions; a carcass composed of one or more carcass plies spanning in a toroidal manner between the pair of bead portions; and The belt portion is composed of one or more belt layers arranged on the outer side of the crown portion of the carcass in the radial direction of the tire, wherein: The cross-sectional width SW of the tire is less than 165 (mm), The ratio of the cross-sectional width SW of the tire to the outer diameter OD of the tire is 0.26 or less, or the cross-sectional width SW (mm) of the tire and the outer diameter OD (mm) of the tire satisfy the relational expression: OD (mm) ≥ -0.0187 × SW (mm) 2 +9.15×SW(mm)-380(mm), and A layer that is arranged on the tire radial direction outer side of the belt portion and covers at least an end portion of the belt portion is provided only in one tire width direction half portion.

2. The pneumatic radial tire for a passenger vehicle according to claim 1, wherein: One or more cover layers are further provided on the outer side of the belt portion in the tire radial direction and on the inner side of the layer in the tire radial direction, and The number of cords per unit width of the cap layer is larger in the one tire width direction half than in the other tire width direction half.

3. The pneumatic radial tire for a passenger vehicle according to claim 1 or 2, wherein: The carcass is composed of a carcass main body portion spanning between the pair of bead portions in an annular shape and a carcass folded back portion folded back from the carcass main body portion around a bead core buried in the bead portion, and An end portion of the carcass folded portion in the one tire width direction half portion is located on the tire radial direction inner side of an end portion of the carcass folded portion in the other tire width direction half portion.

Images