JP2011016490A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which can reduce its rolling resistance by mitigating the concentration of stress to land blocks.SOLUTION: The pneumatic tire 1 has a plurality of land blocks 11, 12 demarcated by tire circumferential grooves 2 to 4 extending in a tire circumferential direction and lateral grooves 5, 6 extending in a tread width direction, wherein chamfered portions 13, 14 extending in the tread width direction are formed at edges of the land blocks 11, 12 on a step-in side. A chamfer amount Vout of the chamfered portion 14 of the land block 12 outward in the tread width direction centered on a tire equator CL is set to be greater than a chamfer amount Vin of the chamfered portion 13 of the land block 11 inward in the tread width direction.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having low rolling resistance.

  Conventionally, in order to reduce noise generated when a tire traveling on a vehicle touches the road surface, a technique for providing a chamfered portion on a land block partitioned by a tire circumferential groove and a lateral groove has been developed ( For example, see Patent Document 1).

  The land block described in Patent Document 1 is provided with a chamfered portion at a corner portion on the outer side in the tread width direction where the chamfer width gradually decreases from the stepping side toward the kicking side.

JP 2003-25810 A

  However, with the pneumatic tire described in Patent Document 1 described above, it is difficult to reduce the rolling resistance of the tire, although it is possible to reduce noise during vehicle travel.

  An object of the present invention is to provide a pneumatic tire capable of reducing the rolling resistance of a tire by reducing stress concentration on a land block.

  The first feature of the present invention is that the pneumatic tire (pneumatic tire 1) according to the present embodiment includes a tire circumferential groove (tire circumferential grooves 2 to 4) extending in the tire circumferential direction and a lateral groove (tread width direction extending in the tread width direction). A plurality of land blocks (land blocks 11, 12) are defined by the transverse grooves 5, 6), and chamfered portions (chamfered portions 13, 14) extending in the tread width direction at the stepped side edge portions of the land blocks. A chamfered amount (chamfered amount Vout) of the chamfered portion in a land block (land block 12) on the outer side in the tread width direction centering on the tire equator (tire equator CL). Is summarized as being set larger than the chamfering amount (chamfering amount Vin) of the chamfered portion of the land block (land block 11) on the inner side in the tread width direction.

  In this way, by chamfering the stepped side edge portion where the stress concentration is large in the land portion block, the stress concentration can be relaxed and the rolling resistance of the tire can be reduced. On the inner side in the tread width direction centering on the tire equator, compressive deformation is mainly caused by load, whereas on the outer side in the tread width direction, shear deformation is added to the compressive deformation. The stress concentration increases on the outer side in the width direction. Accordingly, the stress relaxation effect is enhanced by increasing the chamfering amount on the outer side in the tread width direction than on the inner side in the tread width direction. Note that the larger the chamfering amount, the smaller the ground contact area of the land block. Therefore, it is preferable to reduce the chamfering amount in view of the braking surface. Therefore, it is possible to suppress a reduction in braking performance by changing the chamfering amount between the center side in the tread width direction and the outer side in the tread width direction.

  In other features, the chamfer width (chamfer width Dout) of the chamfered portion (chamfered portion 14) in the land block (land portion block 12) on the outer side in the tread width direction is the land block on the inner side in the tread width direction. The gist is that it is set larger than the chamfer width (chamfer width Din) of the chamfered portion (chamfered portion 13) in the (land portion block 11).

  In other features, the chamfering angle (chamfering angle αout) of the chamfered portion (chamfered portion 14) of the land block (land block 12) on the outer side in the tread width direction is the land block on the inner side in the tread width direction. The gist is that it is set to be larger than the chamfering angle (chamfering angle αin) of the chamfering portion (chamfering portion 13) in the (land portion block 11).

  In other features, a plurality of land blocks (land blocks 32 to 35) are formed by tire circumferential grooves (tire circumferential grooves 2 to 4) extending in the tire circumferential direction and lateral grooves (lateral grooves 5 and 6) extending in the tread width direction. The chamfered portions (chamfered portions 41 and 42) extending in the tread width direction are formed at the stepped side edge portion of the land block, and the tire mounting direction is designated and set as a negative camber. Chamfering width (chamfering width d (in)) of a chamfered portion (chamfered portion 41) in a land block (lander block 32) that is a pneumatic tire (pneumatic tire 31) on the inner side in the tire mounting direction. Is summarized as being larger than the chamfering width (chamfering width d (out)) of the chamfered portion (chamfered portion 42) in the land portion block (land portion block 35) on the outer side in the tire mounting direction.

  In other features, the chamfering angle (chamfering angle β (in)) of the chamfered portion (chamfered portion 41) in the land portion block (land portion block 32) on the inner side in the tire mounting direction is set on the outer side in the tire mounting direction. The gist is that it is larger than the chamfering angle (chamfering angle β (out)) of the chamfered portion (chamfered portion 42) in the land portion block (land portion block 35).

  According to the pneumatic tire of the present invention, the stress concentration on the land block can be alleviated and the rolling resistance of the tire can be reduced.

It is a top view of the tread of the pneumatic tire by a 1st embodiment of the present invention. It is sectional drawing by the AA line of FIG. It is sectional drawing by the BB line of FIG. It is sectional drawing corresponding to FIG. 2, and has shown the chamfering angle of the chamfering part of a land block. It is sectional drawing corresponding to FIG. 3, and has shown the chamfering angle of the chamfer part of a land block. It is the schematic which shows the state which the pneumatic tire is rolling on the road surface. It is a top view of the tread of the pneumatic tire by a 2nd embodiment of the present invention. It is sectional drawing by CC line of FIG. It is sectional drawing by the DD line | wire of FIG. It is sectional drawing corresponding to FIG. 8, and has shown the chamfering angle of the chamfering part of a land block. It is sectional drawing corresponding to FIG. 9, and has shown the chamfering angle of the chamfering part of a land block.

  Hereinafter, details of a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic, and the thicknesses and ratios of the material layers are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

[First embodiment]
FIG. 1 is a plan view of a tread of a pneumatic tire according to a first embodiment of the present invention.

  The tread of the pneumatic tire 1 includes tire circumferential grooves 2, 3 and 4 extending in the tire circumferential direction (hereinafter referred to as tire circumferential direction) and lateral grooves 5 extending in the tire tread width direction (hereinafter referred to as tread width direction). , 6 are provided in plural, and the land portion block 10 is formed by the tire circumferential direction grooves 2 to 4 and the tread width direction grooves 5 and 6.

  The land block includes an inner land block 11 disposed on the inner side in the tread width direction around the tire equator CL, and an outer land block 12 disposed on both lateral sides of the inner land block 11. The inner land portion block 11 is formed with a shorter length in the tire circumferential direction than the outer land portion block 12. Chamfered portions 13 and 14 extending along the tread width direction are formed at the step-side edge portions of the inner land portion block 11 and the outer land portion block 12.

  2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG. As shown in FIGS. 2 and 3, the cross section of the inner land block 11 and the outer land block 12 is formed in a substantially rectangular shape, and the stepping side vertical surface 15 disposed on the stepping side and the kicking side are arranged on the kicking side. The kicking side vertical surface 16 and a grounding surface 17 that connects the tops of the stepping side vertical surface 15 and the kicking side vertical surface 16 are provided.

  A chamfered portion 13 is formed at the stepped side edge portion of the inner land portion block 11, and a chamfered portion 14 is formed at the stepped side edge portion of the outer land portion block 12. The chamfering amount Vout of the chamfered portion 14 in the outer land block 12 is set larger than the chamfered amount Vin of the chamfered portion 13 in the inner land block 11. Here, the chamfering amount is the volume of the shaded portion in FIGS. 2 and 3, and is the volume of a triangular prism with a rectangular parallelepiped edge portion cut out.

  Further, the chamfering width Dout of the chamfered portion 14 in the outer land block 12 is set larger than the chamfered width Din of the chamfered portion 13 in the inner land block 11. Here, the chamfering width is the length in the tire circumferential direction along the inclined surface of the chamfered portion shown in FIGS.

  FIG. 4 is a cross-sectional view corresponding to FIG. 2 and shows the chamfer angle of the chamfered portion of the land block. FIG. 5 is a cross-sectional view corresponding to FIG. 3 and shows the chamfer angle of the chamfered portion of the land block.

  As shown in FIGS. 4 and 5, the chamfering angle αout of the chamfered portion 14 in the outer land block 12 is set larger than the chamfered angle αin of the chamfered portion 13 in the inner land block 11. Here, as shown in FIGS. 4 and 5, the chamfering angle is an angle at which the extension line of the ground contact surface 17 of the land block 11, 12 intersects with the extension line of the inclined surface of the chamfering part 13, 14. is there. Usually, the chamfer angle is preferably 45 °.

  FIG. 6 is a schematic view showing a state where the pneumatic tire is rolling on the road surface.

  When the pneumatic tire 1 rotates in the direction of the arrow and travels on the road surface R, the tread is distorted on the stepping side of the tire 1 and is released on the kicking side. The stress is more concentrated in the edge portion 23 than in the edge portion 24 on the kicking side.

  Below, the effect by this embodiment is demonstrated.

  (1) In the pneumatic tire 1 according to the present embodiment, a plurality of land blocks 11 and 12 are defined by tire circumferential grooves 2 to 4 extending in the tire circumferential direction and lateral grooves 5 and 6 extending in the tread width direction. A pneumatic tire in which chamfered portions 13 and 14 extending in the tread width direction are formed at edge portions on the stepping side in the blocks 11 and 12, and the land block 12 on the outer side in the tread width direction around the tire equator CL. The chamfering amount Vout of the chamfered portion 14 is set larger than the chamfering amount Vin of the chamfered portion 13 in the land block 11 on the inner side in the tread width direction.

  In this way, by chamfering the stepped side edge portion of the land blocks 11 and 12 where the stress concentration is large, the stress concentration can be relaxed and the rolling resistance of the tire can be reduced. In addition, compression deformation due to a load is mainly performed on the inner side in the tread width direction around the tire equator CL, whereas on the outer side in the tread width direction, since shear deformation is applied to the compression deformation, the inner side in the tread width direction is more than the central side in the tread width direction. The stress concentration increases on the outer side in the tread width direction. Accordingly, the stress relaxation effect is enhanced by increasing the chamfering amount on the outer side in the tread width direction than on the inner side in the tread width direction. Note that the larger the chamfering amount, the smaller the ground contact area of the land block. Therefore, it is preferable to reduce the chamfering amount in view of the braking surface. Therefore, it is possible to suppress a reduction in braking performance by changing the chamfering amount between the center side in the tread width direction and the outer side in the tread width direction.

(2) The chamfering width Dout of the chamfered portion 14 in the land block 12 outside the tread width direction is set to be larger than the chamfering width Din of the chamfered portion 13 in the land block 11 inside the tread width direction. Yes. Since a greater stress is concentrated on the land block 12 on the outer side in the tread width direction, the chamfer width Dout of the land block 12 on the outer side in the tread width direction is set to be larger than the chamfer width Din of the land block 11 on the inner side in the tread width direction. By enlarging it, it is possible to reduce the stress concentration and to suppress a reduction in braking performance.

(3) The chamfering angle αout of the chamfered portion 14 in the land block 12 outside the tread width direction is set larger than the chamfered angle αin of the chamfered portion 13 in the land block 11 inside the tread width direction. Yes. Since a greater stress is concentrated on the land block 12 on the outer side in the tread width direction, the chamfering angle αout of the land block 12 on the outer side in the tread width direction is set to be greater than the chamfering angle αin of the land block 11 on the inner side in the tread width direction. By enlarging it, it is possible to reduce the stress concentration and to suppress a reduction in braking performance.

[Second Embodiment]
Next, a second embodiment will be described, but the same reference numerals are given to the same structural portions as those in the first embodiment, and the description will be omitted.

  As shown in FIG. 7, in this embodiment, the tire mounting direction is specified and the pneumatic tire 31 is set as a negative camber, and the chamfering amount of the chamfered portion in the land block inside the tire mounting direction is The feature is that the chamfering amount of the chamfered portion of the land block outside the tire mounting direction is larger. Land blocks 32, 33, 34, and 35 are arranged in order from the inside to the outside in the tire mounting direction.

  8 is a cross-sectional view taken along line CC in FIG. 7, and FIG. 9 is a cross-sectional view taken along line DD in FIG.

  A chamfered portion is formed at the edge portion of the land block on the tire mounting direction outer side and the tire mounting direction inner side. As shown in FIGS. 8 and 9, the cross section of the land portion block 32 on the innermost side in the mounting direction is formed with a chamfered portion 41 at the stepped-side edge portion as shown in FIG. 9. The chamfer width of the chamfered portion 41 is set to a dimension of d (in). On the other hand, as shown in FIG. 8, the cross section of the land portion block 35 at the outermost mounting direction has a chamfered portion 42 formed at the edge portion on the stepping side. The chamfer width of the chamfered portion 42 is set to a dimension of d (out). Here, the chamfer width is the length in the tire circumferential direction along the inclined surface of the chamfered portion.

  FIG. 10 is a cross-sectional view corresponding to FIG. 8 and shows the chamfer angle of the chamfered portion of the land block. FIG. 11 is a cross-sectional view corresponding to FIG. 9 and shows the chamfering angle of the chamfered portion of the land block.

  As shown in FIGS. 10 and 11, the chamfering angle β (in) of the chamfer 41 in the mounting inner land block 32 is equal to the chamfering angle β (out) of the chamfering portion 42 in the mounting outer land block 35. ) Is set larger than. Here, the chamfer angle is an angle at which the extended line of the ground contact surface of the land block intersects with the extended line of the inclined surface of the chamfered part.

    Below, the effect by this embodiment is demonstrated.

  (1) A plurality of land blocks 32 to 35 are defined by tire circumferential grooves 2 to 4 extending in the tire circumferential direction and lateral grooves 5 and 6 extending in the tread width direction, and edge portions on the stepping side in the land blocks 32 to 35 Are chamfered portions 41 and 42 extending in the tread width direction, and a pneumatic tire 31 that is designated as a tire mounting direction and set as a negative camber, and is a surface of the land block 32 on the inner side in the tire mounting direction. The chamfering width d (in) of the chamfered portion 41 is larger than the chamfered width d (out) of the chamfered portion 42 in the land block 35 on the outer side in the tire mounting direction.

  Since the negative camber concentrates the stress toward the inner side of the tire, the stress concentration of the tire is alleviated by increasing the chamfer width d (in) of the chamfered portion 41 on the inner side of the tire than the outer side of the tire. Rolling resistance is reduced.

  (2) The chamfering angle β (in) of the chamfered portion 41 in the land portion block 32 on the inner side in the tire mounting direction is the chamfered angle β (out) of the chamfered portion 42 in the land block 35 on the outer side in the tire mounting direction. Bigger than.

  Since the negative camber concentrates stress toward the inside of the tire, the stress concentration of the tire is alleviated by increasing the chamfering angle β (in) of the chamfered portion 41 on the inside of the tire than on the outside of the tire. Rolling resistance is reduced.

  It should not be understood that the description and the drawings, which form part of the disclosure of the above-described embodiments, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the first and second embodiments, the case where the inclined surface of the chamfered portion is flat has been described, but the inclined surface may be curved.

  Next, the present invention will be described more specifically through examples.

  Pneumatic tires having a size of 195 / 65R15 were used as test tires according to examples and comparative examples. Each tire was filled with air so that the internal pressure was 220 kPa, and mounted on a rim wheel having a load of 73% of the maximum load of JATMA according to JATMA standard. The rolling resistance using an indoor drum tester was verified at a speed of 80 km / hour. Specifically, a constant load was applied to the tire and the tire was rotated at a constant speed of 80 km / hour, and the resistance in the traveling direction generated on the ground contact surface of the drum was measured.

  In the example, chamfering was performed on the stepped side edge portion of the land block. The chamfer width was 2 mm and the chamfer angle was 45 °. In the comparative example, the edge portion of the land block was not chamfered.

  Next, the test tire according to the example was set to a 1 ° negative camber. On the other hand, the test tire according to the comparative example was also set to a 1 ° negative camber, but the edge portion of the land block was not chamfered.

  The rolling resistance coefficient (RRC) of the test tire according to the comparative example was 74.3. On the other hand, the rolling resistance coefficient (RRC) of the test tire according to the example was 73.4. In addition, when the rolling resistance coefficient of the test tire according to the comparative example is 100, the rolling resistance coefficient of the test tire according to the example is 99.

  From the above experimental results, it has been found that according to the example, the rolling resistance of the tire can be reduced.

1,31 Pneumatic tire 2,3,4 Tire circumferential groove 5,6 Cross groove 11, 12, 32, 33, 34, 35 Land block 13, 14, 41, 42 Chamfer

Claims (7)

A plurality of land blocks are defined by a tire circumferential groove extending in the tire circumferential direction and a lateral groove extending in the tread width direction, and a chamfered portion extending in the tread width direction is formed at the stepped side edge portion of the land block. Tire,
The chamfering amount of the chamfered portion of the land block outside the tread width direction centered on the tire equator is larger than the chamfering amount of the chamfered portion of the land block inside the tread width direction. Enter tire.   2. The air according to claim 1, wherein the chamfered width of the chamfered portion in the land block on the outer side in the tread width direction is larger than the chamfered width of the chamfered portion in the land block on the inner side in the tread width direction. Enter tire.   The chamfering angle of the chamfered portion in the land portion block on the outer side in the tread width direction is larger than the chamfering angle of the chamfered portion in the land portion block on the inner side in the tread width direction. Pneumatic tires.   The chamfering width of the chamfered portion in the land block on the inner side in the tread width direction is larger than the chamfered width of the chamfered portion in the land block on the outer side in the tread width direction. The pneumatic tire according to claim 1.   The chamfering angle of the chamfered portion in the land portion block on the inner side in the tread width direction is larger than the chamfering angle of the chamfered portion in the land portion block on the outer side in the tread width direction. The pneumatic tire according to claim 1. A plurality of land blocks are defined by a tire circumferential groove extending in the tire circumferential direction and a lateral groove extending in the tread width direction, and a chamfered portion extending in the tread width direction is formed at the stepped side edge portion of the land block. , A pneumatic tire in which the tire mounting direction is specified and set as a negative camber,
A pneumatic tire characterized in that the chamfer width of the chamfered portion in the land portion block inside the tire mounting direction is larger than the chamfer width of the chamfered portion in the land block outside the tire mounting direction.   The air according to claim 6, wherein a chamfering angle of the chamfered portion in the land block inside the tire mounting direction is larger than a chamfering angle of the chamfered portion in the land block outside the tire mounting direction. Tires.

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