JP2010083303A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire suppressing any heel-and-toe wear even when a projecting part in the tire circumferential direction is provided on an end of a kick side of a block. <P>SOLUTION: A chamfered portion 7b is provided on a projecting part 7a provided on a kick side end of a block 7, the ground contact pressure of the projecting part 7a is reduced to suppress the heel-and-toe wear, which is considerably effective for reducing the noise during the traveling condition. In this case, the chamfered portion 7b is formed so that the chamfering length L1 from one end P1 in the tire circumferential direction to the other end P2 is larger on the center side in the width direction of the projecting part 7a than that on both sides in the width direction, and the ground contact pressure can be substantially uniform from the center side (the fore end side) in the width direction to be worn mostly at the projecting part 7a to both sides in the width direction, and the partial wear resistance can be enhanced without degrading the steering stability. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire used in, for example, passenger cars, trucks, buses and the like.

Conventionally, as this type of pneumatic tire, a block is generally formed by a main groove extending in the tire circumferential direction and a lug groove extending in the tire width direction, but the kicking side end of the block is a road surface. In order to reduce noise at the time of contact, the block's kick-out side end is provided at the block's kick-out side end by providing a protrusion in which the center side in the width direction of the block protrudes in the tire circumferential direction from both sides in the width direction. Is known that gradually contacts the road surface in the tire width direction (see, for example, Patent Document 1).
JP-A-9-207520

  However, the block has a problem that so-called heel and toe wear (a kind of uneven wear) is likely to occur. Heel-and-toe wear occurs when the block receives repeated shearing force in the tire rotation direction due to the braking force of the tire, and wear increases due to high ground pressure on the kicking side of the block, while ground pressure occurs on the stepping side of the block. The edge portion extends thinly due to wear due to sliding with the road surface, and noise increases due to the hitting sound of the extended portion hitting the road surface. In particular, in the case where the protruding portion as described above is provided on the kicking side of the block, there is a problem that the contact pressure on the kicking side of the block is increased by that amount, and heel and toe wear is increased.

  The present invention has been made in view of the above problems, and the object of the present invention is to provide heel and toe wear even when a protruding portion protruding in the tire circumferential direction is provided at the kicking side end portion of the block. It is providing the pneumatic tire which can be suppressed.

  In order to achieve the above object, the present invention comprises a main groove extending in the tire circumferential direction, a lug groove extending in the tire width direction, and a block defined by the main groove and the lug groove, and the kicking side end of the block In a pneumatic tire in which a central portion in the width direction of the block is provided with a protruding portion that protrudes in the tire circumferential direction from both sides in the width direction, a chamfered portion between the grounding surface of the block and the groove wall surface of the lug groove on the protruding portion side The chamfered portion is formed such that the chamfered length from one end to the other end in the tire circumferential direction is longer on the center side in the width direction than on both sides in the width direction of the protruding portion.

  Thereby, since the chamfered portion is provided at the protruding portion provided at the kick-out side end portion of the block, the ground pressure of the protruding portion is reduced, and heel and toe wear is suppressed. In this case, the chamfered portion is formed so that the chamfered length from one end to the other end in the tire circumferential direction is longer at the center in the width direction than the both sides in the width direction. The contact pressure is substantially uniform from the center in the width direction (tip side) to both sides in the width direction.

  According to the present invention, since the contact pressure of the projecting portion can be reduced, heel and toe wear can be suppressed, which is extremely effective in reducing noise during traveling. In this case, since the contact pressure can be made substantially uniform from the center in the width direction (tip side) where the protrusions are most likely to be worn to both sides in the width direction, uneven wear resistance can be achieved without deteriorating steering stability. Improvements can be made.

  1 to 4 show a first embodiment of the present invention. FIG. 1 is a partial front sectional view of a pneumatic tire, FIG. 2 is a partial plan view thereof, FIG. 3 is a plan view of a block, and FIG. FIG.

  The pneumatic tire shown in the figure is formed between a tread portion 1 formed on the tire outer peripheral surface side, sidewall portions 2 formed on both sides in the tire width direction, and the tread portion 1 and the sidewall portions 2. A shoulder portion 3 and a bead portion 4 formed on the inner side in the tire radial direction of the sidewall portion 2, and a bead core 4 a is embedded in the bead portion 4.

  The tread portion 1 is provided with a plurality of main grooves 5 extending in the tire circumferential direction, a plurality of lug grooves 6 extending in the tire width direction, and a plurality of blocks 7 defined by the main grooves 5 and the lug grooves 6. Yes. Each block 7 is provided with a protruding portion 7a at the center side in the width direction that protrudes in the tire circumferential direction from both sides in the width direction, and the kicking side end portion of the protruding portion 7a is the center in the width direction. It is formed so as to form a curved shape from the side to both ends. Further, a chamfered portion 7b is provided between the grounding surface of the block 7 and the groove wall surface of the lug groove 6 on the protruding portion 7a side, and the chamfered portion 7b has a chamfered length from one end P1 to the other end P2 in the tire circumferential direction. L1 is formed so that the center side in the width direction is gradually longer than both sides in the width direction of the protruding portion 7a. In this case, in the chamfered portion 7b, the chamfered length L1 of the longest portion of the chamfered length L1 is the length from the kicking side end of the block 7 to the stepped side end (the chamfered length L1). The length of the chamfered portion 7b from the other end P2 in the tire circumferential direction to the stepped-side end portion P3 of the block 7 is 2% to 20%. Further, the chamfered portion 7b is formed such that the chamfering depth H in the tire radial direction at the end portion on the kick-out side of the portion having the longest chamfering length L1 is 1 mm or more and 2 mm or less.

  In the pneumatic tire configured as described above, since the chamfered portion 7b is provided on the protruding portion 7a of the block 7, the ground pressure of the protruding portion 7a is reduced, and heel and toe wear is suppressed. In this case, the chamfering length L1 from the tire circumferential direction one end P1 to the other end P2 of the chamfered portion 7b is longer at the center in the width direction of the protruding portion 7a than at both sides in the widthwise direction. The contact pressure is almost uniform from the center in the width direction (tip side) to both sides in the width direction.

  Thus, according to the present embodiment, since the chamfered portion 7b is provided on the protruding portion 7a provided at the kick-out side end portion of the block 7, the ground pressure of the protruding portion 7a is reduced and heel and toe wear is suppressed. It is extremely effective in reducing noise during driving. In this case, the chamfered portion 7b is formed so that the chamfering length L1 from the tire circumferential direction one end P1 to the other end P2 is longer at the center in the width direction of the protruding portion 7a than at both sides in the width direction. A substantially uniform contact pressure can be obtained from the widthwise center side (tip side), which tends to wear, to both sides in the width direction, and uneven wear resistance can be improved without deteriorating steering stability.

  Further, in the chamfered portion 7b, the chamfering length L1 of the longest portion of the chamfering length L1 is 2% or more and 20% or less of the length from the block kicking side end to the stepping side end of the block. Therefore, the effect of suppressing the heel and toe wear can be sufficiently obtained without reducing the ground contact area of the block 7 more than necessary by chamfering.

  Further, since the kick-out side end portion of the protruding portion 7a is formed to be curved from the width direction center side to both end sides, the amount of wear on the width direction center side (tip side) of the protrusion portion 7a is partially Therefore, uneven wear in the width direction of the protrusion 7a can be suppressed.

  Further, since the chamfered portion 7b is formed so that the chamfering depth H in the tire radial direction at the kick-out side end portion of the longest portion of the chamfer length L1 is 1 mm or more and 2 mm or less, the chamfering blocks more than necessary. The effect of suppressing the heel and toe wear can be sufficiently obtained without reducing the contact area of 7.

  FIG. 5 is a side sectional view of a block showing a second embodiment of the present invention, in which the chamfered portion 7b of the projecting portion 7a is convex outward in the tire radial direction from one end P1 to the other end P2. It is formed in a curved shape. Thereby, since the kicking side end of the block 7 gradually contacts the road surface in the tire circumferential direction, the wear amount of the chamfered portion 7b can be further reduced.

  FIG. 6 is a side cross-sectional view of a block showing a third embodiment of the present invention, in the tire radial direction from one groove wall surface 6a to the other groove wall surface 6b on the protruding portion 7a side at the bottom of the lug groove 6. The bottom raised portion 6c in which the groove depth D gradually decreases is provided. Thereby, since the rigidity by the side of the protrusion part 7a in the block 7 can be improved, the abrasion loss of the chamfering part 7b can be reduced more.

  In this case, if the bottom raised portion 6c is formed so that the groove depth D of the groove wall surface 6b on the protruding portion 7a side becomes shallower as the chamfer length L1 of the protruding portion 7a becomes longer, the rigidity on the protruding portion 7a side protrudes. Appropriate rigidity corresponding to the chamfering length L1 can be obtained over the width direction of the portion 7a, which is effective in improving the steering stability.

  FIG. 7 is a side cross-sectional view of a block showing a fourth embodiment of the present invention, in which the groove wall surface 6b on the protruding portion 7a side of the lug groove 6 is inclined so that the groove width decreases from the outer side in the tire radial direction toward the inner side. It is formed by. Thereby, since the rigidity by the side of the protrusion part 7a in the block 7 can be improved, the abrasion loss of the chamfering part 7b can be reduced more.

  In this case, by forming the groove wall surface 6b on the projecting portion 7b side so that the inclination angle θ with respect to the tire radial direction is not less than 1 ° and not more than 10 °, the effect of reducing the wear amount can be sufficiently obtained without excessively increasing the rigidity. Obtainable.

  Further, if the groove wall surface 6b on the projecting portion side is formed so that the inclination angle θ with respect to the tire radial direction becomes larger as the chamfer length L1 of the projecting portion 7a becomes longer, the rigidity on the projecting portion 7a side is increased. Appropriate rigidity according to the chamfering length L1 can be obtained in the width direction, which is effective in improving the steering stability.

  When Examples 1 to 6, the conventional example, and the comparative example of the present invention were tested for uneven wear resistance, the results shown in FIG. 8 were obtained. Here, the tire which does not have a chamfering part in the protrusion part of a block was used as a prior art example, and the tire which has a chamfering part in the protrusion part of a block was used for Comparative Examples 1-3 and Examples 1-6. In this case, in Comparative Example 1, a chamfering length L1 having the same length (1.0 mm) in the width direction of the protruding portion and a chamfering depth H of 1.0 mm was used. In Comparative Examples 2-3 and Examples 1-6, the value (L1 / (L1 + L2)) obtained by dividing the chamfering length L1 by the length L2 from the kicking side end to the stepping side end of the block 7 Those having 0.01, 0.25, 0.02, 0.10, 0.20, 0.10, 0.10, and 0.10, respectively, and chamfering depths H of 1.0 mm were used. Of these, in Example 4, as in the second embodiment, the chamfered portion 7b is formed in a curved shape that protrudes outward in the tire radial direction from one end P1 to the other end P2 in the tire circumferential direction. Except for Example 4, those formed linearly were used. Further, in Example 5, the bottom raised portion 6c is provided at the bottom of the lug groove 6 as in the third embodiment, and in Example 6, the protruding portion in the lug groove 6 as in the fourth embodiment. What formed the groove wall surface 6b by the side of 7a by the inclined surface was used. In this test, tires having a tire size of 205 / 60R16 and an air pressure of 230 kPa were mounted on an actual vehicle.

  In this test, after traveling 20000 km on a general road, the difference in wear amount between the kicking side end and the stepping side end of the block was measured and its reciprocal number was indexed. In this case, it was determined that an index value of 120 or more is superior. As a result of the test, Comparative Examples 1 to 3 are all excellent in uneven wear resistance compared to the conventional example, and Examples 1 to 6 are all excellent in uneven wear resistance compared to Comparative Examples 1 to 3. was gotten.

Partial front sectional view of the pneumatic tire showing the first embodiment of the present invention Partial plan view of pneumatic tire Block top view Side sectional view of block Side surface sectional drawing of the block which shows the 2nd Embodiment of this invention Side surface sectional drawing of the block which shows the 3rd Embodiment of this invention Side surface sectional drawing of the block which shows the 4th Embodiment of this invention Diagram showing test results

Explanation of symbols

  3 ... shoulder part, 5 ... main groove, 6 ... lug groove, 6a, 6b ... groove wall, 6c ... bottom raised part, 7 ... block, 7a ... projecting part, 7b ... chamfered part.

Claims (10)

A main groove extending in the tire circumferential direction; a lug groove extending in the tire width direction; and a block defined by the main groove and the lug groove. In a pneumatic tire provided with a protruding portion that protrudes more in the tire circumferential direction than
A chamfered portion is provided between the grounding surface of the block and the groove wall surface of the lug groove on the protruding side,
A pneumatic tire characterized in that the chamfered portion is formed such that the chamfered length from one end to the other end in the tire circumferential direction is longer on the center in the width direction than on both sides in the width direction of the protruding portion. The chamfered portion is formed such that the chamfered length of the portion having the longest chamfered length is 2% or more and 20% or less of the length from the kicking side end portion to the stepping side end portion of the block in that portion. The pneumatic tire according to claim 1, characterized in that: The pneumatic tire according to claim 1 or 2, wherein the kick-out side end portion of the protruding portion is formed in a curved shape from the center side in the width direction to both end sides. The chamfered portion is formed such that a chamfering depth in a tire radial direction at a kick-out side end portion of a portion having the longest chamfering length is 1 mm or more and 2 mm or less. The described pneumatic tire. The pneumatic tire according to claim 1, 2, 3, or 4, wherein the chamfered portion is formed in a curved shape that protrudes outward in the tire radial direction from one end in the tire circumferential direction to the other end. The bottom part of the said lug groove was provided with the bottom raising part from which the groove depth of a tire radial direction becomes shallow gradually toward the other groove wall surface by the side of a protrusion from one groove wall surface. The pneumatic tire according to 3, 4, or 5. The pneumatic tire according to claim 6, wherein the bottom raised portion is formed so that the groove depth of the groove wall surface on the protruding portion side becomes shallower when the chamfer length of the protruding portion becomes longer. The groove wall surface on the protruding portion side in the lug groove is formed by an inclined surface in which the groove width decreases from the outer side in the tire radial direction toward the inner side in the tire radial direction. The described pneumatic tire. The pneumatic tire according to claim 8, wherein the groove wall surface on the protruding portion side is formed so that an inclination angle with respect to a tire radial direction is not less than 1 ° and not more than 10 °. The pneumatic tire according to claim 8 or 9, wherein the groove wall surface on the protruding portion side is formed such that when the chamfering length of the protruding portion is increased, an inclination angle with respect to the tire radial direction is increased.

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