JP5661324B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which a plurality of blocks are formed in a tread portion.

  Conventionally, in a pneumatic tire in which a plurality of blocks are configured as a tire tread, various measures have been tried because uneven wear, particularly heel antow wear, is a problem. For example, Patent Document 1 discloses that a part of a width direction groove for partitioning a block is shallow, that is, by providing a bottom-up portion, the stress against the collapse deformation of the block in the tire width direction is increased, A method is disclosed in which an increase in the input load is suppressed and uneven wear due to collapse deformation is prevented.

  However, in the tire described in Patent Document 1, although there is a certain effect in preventing uneven wear, the rigidity of the block land portion becomes too high, and the block land portion breaks due to baldness and cracks when rolling the tire. There is a risk of inviting.

JP-A-6-171318

  The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a pneumatic tire capable of suppressing uneven wear of the block and suppressing damage to the block itself.

This invention is made | formed in view of the said fact, Comprising: The pneumatic tire of Claim 1 is provided in the tread, The several circumferential groove | channel extended along the tire circumferential direction, and the said circumferential groove | channel A pneumatic tire having a block land portion defined by a plurality of lateral grooves extending in a crossing direction, wherein the circumferential groove has a deep groove bottom and a shallow groove having a shallower groove than the deep groove bottom. has a bottom, said deep groove bottom, widest width toward the leading side of the block land portion is a narrowed shape width in the tire width direction at the trailing side of the block land portion, the tire equatorial plane Formed on the tire equatorial plane side of the circumferential groove that divides the block land portion disposed above and adjacent to the block land portion, and the extension distance from the block land portion on the kick-out side is the circumference 10% to 100% of the total width of the directional groove Der Rukoto, and said.

  Here, uneven wear of the tire, particularly heel and toe wear, is caused by excessive deformation of the block land portion at the time of tire load rolling. There is little wear at the kicking end of the block land portion (the portion that comes into contact with the ground lastly) so that the amount of wear increases. Excessive wear at the kicking end is caused by a circumferential force acting in the tire contact surface.

In the present invention, by changing the depth of the circumferential groove, the rubber of the tire compressed in the deep portion of the groove escapes, and the circumferential force acting on the tire contact surface can be reduced. Thereby, heel and toe wear can be suppressed. Moreover, since the depth of the groove bottom is changed in the tire width direction, instead of uniformly deepening the circumferential groove, cracks in the groove bottom can be suppressed.

  In the present invention, since the bottom raised portion for preventing the collapse of the block land portion is provided in the lateral grooves arranged on both sides in the circumferential direction of the block land portion, the rigidity of the block land portion is high. It is also possible to suppress damage to the block land portion itself.

  Among the block land parts, the block land part closer to the tire equatorial plane has a higher contact pressure, so by increasing the depth of the circumferential groove bottom, the circumferential force acting on the tire contact surface is effectively reduced. Heel and toe wear can be suppressed.

Further, in the pneumatic tire, the groove bottom of the circumferential groove may be an inclined bottom inclined in the tire width direction.

  Thus, the depth in the tire width direction can be changed by inclining the groove bottom of the circumferential groove in the tire width direction.

The pneumatic tire according to claim 2 is characterized in that the deep groove bottom has a triangular shape having a vertex on the stepping side of the block land portion in a plan view.
The pneumatic tire according to claim 3 , wherein a groove bottom depth of the shallowest portion of the circumferential groove is 50% to 90% of a groove depth of the deepest portion of the circumferential groove. To do.

  Thus, by setting the depth range of the circumferential groove, heel and toe wear can be satisfactorily suppressed.

  As described above, according to the present invention, damage to the block itself can be suppressed while suppressing uneven wear of the block.

(A) of the tread of the pneumatic tire concerning a 1st embodiment is a top view, and (B) is a partial sectional view. It is a partial cross section figure of the tread of the pneumatic tire which concerns on the modification of 1st Embodiment. It is a partial sectional view of the tread of the pneumatic tire concerning other modifications of a 1st embodiment. (A) of the tread of the pneumatic tire which concerns on the modification of 1st Embodiment is a top view, (B) is a partial cross section figure. (A) of the tread of the pneumatic tire concerning a 2nd embodiment is a top view, and (B) is a partial sectional view. It is a partial cross section figure of the tread of the pneumatic tire which concerns on the modification of 2nd Embodiment. It is a partial cross section figure of the tread of the pneumatic tire concerning other modifications of a 2nd embodiment. (A) of the tread of the pneumatic tire concerning a 3rd embodiment is a top view, and (B) is a partial sectional view. (A) of the tread of the pneumatic tire which concerns on the modification of 3rd Embodiment is a top view, (B) is a partial cross section figure. (A) of the tread of the pneumatic tire concerning other modifications of a 3rd embodiment is a top view, and (B) is a partial sectional view. It is a top view of the tread of the pneumatic tire which tested.

[First embodiment]
Hereinafter, a pneumatic tire 10 according to a first embodiment of the present invention will be described with reference to the drawings. A one-dot chain line CL in the figure indicates the tire equator plane.

  FIG. 1A shows a tread 12 of a pneumatic tire 10. The tread 12 has a ground contact end 12E, which is a pneumatic tire 10 mounted on a standard rim defined in JATMA YEAR BOOK (Japan Automobile Tire Association Standard, 2010 edition) and applicable size and ply rating in JATMA YEAR BOOK. When the maximum load capacity is loaded with 100% internal pressure of the air pressure (maximum air pressure) corresponding to the maximum load capacity (bold load in the internal pressure-load capacity correspondence table). When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  In addition, since the internal structure of the pneumatic tire 10 of this embodiment is the same as that of a general pneumatic tire (equipped with a carcass, a bead, etc.), detailed description of the internal structure is omitted.

  In the tread 12 of the pneumatic tire 10 of the present embodiment, a first circumferential groove 14 and a second circumferential groove 15 which are a plurality of (four in the present embodiment) circumferential grooves extending along the tire circumferential direction. A third circumferential groove 16 and a fourth circumferential groove 17 are formed. The tread 12 has a plurality of lateral grooves 20 extending in the tire width direction.

A first land portion 22 is formed between the first circumferential groove 14 and the second circumferential groove 15. The 1st land part 22 is divided by the horizontal groove 20, and the some 1st block 22B is comprised. A center land portion 24 is formed between the second circumferential groove 15 and the third circumferential groove 16. The center land portion 24 is partitioned by the lateral groove 20, and a plurality of center blocks 24B are configured. A second land portion 26 is configured between the third circumferential groove 16 and the fourth circumferential groove 17. The second land portion 26 is partitioned by the lateral groove 20 to form a plurality of second blocks 26B.

A shoulder land portion 28 is formed on the shoulder side of the first circumferential groove 14 and on the shoulder side of the fourth circumferential groove 17, respectively.

As shown in FIG. 1B, the groove bottom of the second circumferential groove 15 includes a deep groove bottom 15A and a shallow groove bottom 15B having a groove depth shallower than the deep groove bottom 15A. The deep groove bottom 15A is configured on the center land portion 24 side (side closer to the tire equatorial plane CL) with a groove depth D1 and a groove width W2. The shallow groove bottom 15B is configured on the first land portion 22 side with a groove depth D2. A step portion 15D is formed between the deep groove bottom 15A and the shallow groove bottom 15B, and the groove bottom of the second circumferential groove 15 has a two-stage configuration as viewed from the tire circumferential direction.

The groove depth D2 of the shallow groove bottom 15B is preferably 50% to 90% of the groove depth D1 of the deep groove bottom 15A. If it is smaller than 50%, the block rigidity becomes high and the block may be damaged. If it is larger than 90%, the block rubber hardly escapes in the tire width direction, and the force acting in the tire circumferential direction at the block kicking end. This is because it cannot be relaxed.

Further, the groove width W2 of the deep groove bottom 15A is preferably 10% to 50% of the total width W1 of the first circumferential groove 15. If it is less than 10%, the side walls of the deep groove bottom 15A come into contact with each other when a load is applied, and the effect is reduced. Because there is.

As shown in FIG. 1B, the groove bottom of the third circumferential groove 16 includes a deep groove bottom 16A and a shallow groove bottom 16B having a groove depth shallower than the deep groove bottom 16A. The deep groove bottom 16A is configured on the center land portion 24 side (side closer to the tire equator plane CL) with a groove depth D3 and a groove width W4. The shallow groove bottom 16B is configured on the second land portion 26 side with a groove depth D4. A step portion 16D is formed between the deep groove bottom 16A and the shallow groove bottom 16B, and the groove bottom of the third circumferential groove 16 has a two-stage configuration as viewed from the tire circumferential direction.

The groove depth D4 of the shallow groove bottom 16B is preferably 50% to 90% of the groove depth D3 of the deep groove bottom 16A. If it is smaller than 50%, the block rigidity becomes high and the block may be damaged. If it is larger than 90%, the block rubber hardly escapes in the tire width direction, and the force acting in the tire circumferential direction at the block kicking end. This is because it cannot be relaxed.

Further, the groove width W4 of the deep groove bottom 16A is preferably 10% to 50% of the total width W3 of the second circumferential groove 16. If it is less than 10%, the side walls of the deep groove bottom 16A come into contact with each other when a load is applied, and the effect is reduced. If it is more than 50%, deformation concentrates on the groove bottom and a groove bottom crack may occur. Because there is.
The groove bottom depths of the first circumferential groove 14 and the fourth circumferential groove 17 are constant.

(Function)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.
In the pneumatic tire 10 of the present embodiment, by changing the groove bottom depths of the second circumferential groove 15 and the third circumferential groove 16, the deep groove bottoms 15A and 16A which are deep portions of the groove, The circumferential force working inside can be reduced. Thereby, the heel and toe wear of the center block 24B can be suppressed.

  Further, in the present embodiment, the horizontal groove 20 arranged on both sides in the circumferential direction of the block land portion is not provided with a bottom raising portion for preventing the collapse of the block land portion, so that the rigidity of the block land portion is increased. It is also possible to suppress damage to the block land itself due to the increase in height.

  In the present embodiment, the groove bottom depths of the first circumferential groove 14 and the fourth circumferential groove 17 are constant, but these circumferential grooves also have a groove bottom having a two-stage configuration. The bottom depth may be changed.

  Moreover, in this embodiment, although the groove bottom by the side of the center land part 24 was deepened in the 2nd circumferential groove 15 and the 3rd circumferential groove 16, as shown in FIG. The groove bottom on the land portion 26 side may be deepened to form the shallow groove bottoms 15B and 16B on the center land portion 24 side, and the deep groove bottoms 15A and 16A on the shoulder side.

  Further, as shown in FIG. 3, in the second circumferential groove 15 and the third circumferential groove 16, deep groove bottoms 15A and 16A are formed at the central portion in the tire width direction so as to deepen the central portion in the tire width direction. The shallow groove bottoms 15B and 16B may be formed on both outer sides.

Further, in the present embodiment, the deep groove bottoms 15A and 16A of the second circumferential groove 15 and the third circumferential groove 16 are configured continuously on the entire circumference in the tire circumferential direction. 4 (A) and 4 (B), it may be configured only in a portion adjacent to the center block 24B, and the groove bottom depth of the lateral groove 20 may be constant in the tire width direction.
Also in this case (when the deep groove portion is formed only in the portion adjacent to the center block 24B), the deep groove bottoms 15A and 16A are connected to the second circumferential groove 15 and the third circumferential groove 16 as shown in FIG. The deep groove bottoms 15 </ b> A and 16 </ b> A may be formed at the center of the second circumferential groove 15 and the third circumferential groove 16 as shown in FIG. 3.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The pneumatic tire 30 of the present embodiment is different from the first embodiment in the configuration of the groove bottoms of the second circumferential groove 15 and the third circumferential groove 16, and the other configurations are the same as those in the first embodiment.

  As shown in FIG. 5B, the bottom of the second circumferential groove 15 is directed from the rising portion of the center land portion 24 (center block 24B) to the rising portion of the first land portion 22 (first block 22B). Thus, the inclined bottom 15C is configured to be inclined so that the groove bottom becomes shallow. That is, the groove bottom of the second circumferential groove 15 is an inclined bottom 15C that is inclined so as to become shallower from the tire equatorial plane CL side toward the ground contact end 12E side of the tread.

  The groove bottom of the third circumferential groove 16 is shallower from the rising portion of the center land portion 24 (center block 24B) toward the rising portion of the second land portion 26 (second block 26B). Inclined bottom 16C is formed. That is, the groove bottom of the third circumferential groove 16 is an inclined bottom 16C that is inclined so as to become shallower from the tire equatorial plane CL side toward the grounding end 12E side of the tread.

The shallowest depth D6 of the inclined bottom 15C is preferably 50% to 90% of the deepest portion depth D5. The depth D7 of the shallowest portion of the inclined bottom 16C is preferably 50% to 90% of the depth D8 of the deepest portion. If it is smaller than 50%, the block rigidity becomes high and the block may be damaged. If it is larger than 90%, the block rubber hardly escapes in the tire width direction, and the force acting in the tire circumferential direction at the block kicking end. This is because it cannot be relaxed.

(Function)
Next, the effect | action of the pneumatic tire 30 of this embodiment is demonstrated.
In the pneumatic tire 30 of the present embodiment, the circumferential direction working in the tire ground contact surface on the side close to the deep center block 24B of the groove by using the second circumferential groove 15 and the third circumferential groove 16 as inclined surfaces. The power of can be reduced. Thereby, the heel and toe wear of the center block 24B can be suppressed.

  Also in the present embodiment, since the bottom grooves for preventing the collapse of the block land portion are provided in the lateral grooves 20 arranged on both sides of the block land portion in the circumferential direction, the rigidity of the block land portion is not provided. It is also possible to suppress damage to the block land itself due to the increase in height.

  In the present embodiment, the groove bottom depths of the first circumferential groove 14 and the fourth circumferential groove 17 are constant, but these circumferential grooves are also inclined bottoms inclined in the tire width direction. The groove bottom depth may be changed.

  In the present embodiment, the groove bottom of the second circumferential groove 15 and the groove bottom of the third circumferential groove 16 are such that the groove bottom depth decreases from the center land portion 24 side toward the tread grounding end 12E. As shown in FIG. 6, the inclined grooves 15C-1 and 16C-1 are inclined so that the groove bottom depth becomes shallower from the tread grounding end 12E side toward the center land portion 24 side, as shown in FIG. Alternatively, as shown in FIG. 7, the inclined grooves 15 </ b> C- 2 and 16 </ b> C- 2 may be inclined so that the center part in the tire width direction is the deepest part.

[Third embodiment]
Next, a third embodiment of the present invention will be described. In the present embodiment, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  The pneumatic tire 40 of the present embodiment is different from the first embodiment in that the tire has directionality in the tire circumferential direction and the configurations of the groove bottoms of the second circumferential groove 15 and the third circumferential groove 16 are different from the first embodiment. Other configurations are the same as those of the first embodiment.

  The rotation direction of the pneumatic tire 40 of the present embodiment is indicated by an arrow R in FIG. In FIG. 8A, the lower side is the stepping side, and the upper side is the kicking side.

  As shown in FIG. 8A, a deep groove bottom 15F is formed on the groove bottom of the second circumferential groove 15 so as to be adjacent to the center block 24B. The portion other than the deep groove bottom 15F is a shallow groove bottom 15E. The deep groove bottom 15F has a triangular shape having an apex on the stepping side in plan view, one side is constituted by the rising portion of the center block 24B, and one side is constituted by an extension line of the edge on the kicking side of the center block 24B, One side is configured such that one end is disposed at the stepped side end of the center block 24B. Accordingly, the deep groove bottom 15F has a width in the tire width direction that is widest on the kicking side and gradually becomes narrower as it approaches the stepping side.

  As shown in FIG. 8B, the extension length S1 from the center block 24B on the kick-out side of the deep groove bottom 15F is 10% to 100% of the full width W1 of the first circumferential groove 15. preferable. This is because if the load is less than 10%, the side walls of the deep groove bottom 15F come into contact with each other and the effect is reduced.

Further, the groove depth D2 of the shallow groove bottom 15E is preferably 50% to 90% of the groove depth D1 of the deep groove bottom 15F. If it is smaller than 50%, the block rigidity becomes high and the block may be damaged. If it is larger than 90%, the block rubber hardly escapes in the tire width direction, and the force acting in the tire circumferential direction at the block kicking end. This is because it cannot be relaxed.

  A deep groove bottom 16F is formed at the groove bottom of the third circumferential groove 16 adjacent to the center block 24B. The portion other than the deep groove bottom 16F is a shallow groove bottom 16E. The deep groove bottom 16F has a triangular shape having an apex on the stepping side in a plan view, one side is constituted by the rising portion of the center block 24B, and one side is constituted by an extension line of the edge on the kicking side of the center block 24B, One side is configured such that one end is disposed at the stepped side end of the center block 24B. Accordingly, the deep groove bottom 16F has a width in the tire width direction that is widest on the kicking side and gradually becomes narrower as it approaches the stepping side.

The extension length S2 from the center block 24B on the kick-out side of the deep groove bottom 16F is preferably 10% to 100% of the entire width W3 of the second circumferential groove 16. This is because when the load is less than 10%, the side walls of the deep groove bottom 16F come into contact with each other and the effect is reduced.
The groove depth D4 of the shallow groove bottom 16E is preferably 50% to 90% of the groove depth D3 of the deep groove bottom 16F. If it is smaller than 50%, the block rigidity becomes high and the block may be damaged. If it is larger than 90%, the block rubber hardly escapes in the tire width direction, and the force acting in the tire circumferential direction at the block kicking end. This is because it cannot be relaxed.

(Function)
Next, the effect | action of the pneumatic tire 40 of this embodiment is demonstrated.
In the pneumatic tire 30 of the present embodiment, by forming deep groove bottoms 15F and 16F having deep groove bottoms in the second circumferential groove 15 and the third circumferential groove 16, respectively, the circumferential direction working in the tire ground contact surface is formed. The power can be reduced. Thereby, the heel and toe wear of the center block 24B can be suppressed. In particular, in this embodiment, since the width of the deep groove bottoms 15F, 16F in the tire width direction is wide on the kicking side where the wear amount is large, the heel and toe wear of the center block 24B can be effectively suppressed.

  Also in the present embodiment, since the bottom grooves for preventing the collapse of the block land portion are provided in the lateral grooves 20 arranged on both sides of the block land portion in the circumferential direction, the rigidity of the block land portion is not provided. It is also possible to suppress damage to the block land itself due to the increase in height.

  In the present embodiment, the groove bottom depths of the first circumferential groove 14 and the fourth circumferential groove 17 are constant, but these circumferential grooves are also deep grooves similar to the deep groove bottoms 15F and 16F. A portion may be configured to change the groove bottom depth.

In the present embodiment, the deep groove bottoms 15F and 16F are formed adjacent to the center block 24B in the second circumferential groove 15 and the third circumferential groove 16, but as shown in FIGS. 9A and 9B. In addition, the deep groove bottoms 15F and 16F may be formed adjacent to the first block 22B and the second block 26B side.
Furthermore, as shown in FIGS. 10A and 10B, deep groove bottoms 15 </ b> F and 16 </ b> F may be formed at the center in the tire width direction in the second circumferential groove 15 and the third circumferential groove 16.

  In the present embodiment, the deep groove bottom 15F has a triangular shape, but the length of the deep groove bottom 15F in the tire width direction may be other shapes such that the stepping side of the block is longer than the kicking side.

  In order to confirm the effect of the present invention, the pneumatic tire according to the above-described first to third embodiments of the present invention (Example) and the pneumatic according to the comparative example in which the groove bottom depth of the circumferential groove is made constant. The tire (comparative example) was tested. As a test, the amount of step difference between the stepped-in end and the kicked-out end of the tire block related to the heel and toe wear performance was measured after traveling 50,000 km. As test conditions, a running distance of 50,000 km, a tire size of 295 / 75R22.5, and an internal pressure of 650 kPa were common to the pneumatic tires related to all tests. Further, as shown in FIG. 11, the groove width, the block length, and the width are all the same, and the groove bottom depth of the lateral groove 20 is 20 mm.

  Regarding the different conditions, the pneumatic tire 10 (FIG. 1) of the first embodiment is the Example 1-in, the pneumatic tire of the first embodiment, and the modified example shown in FIG. Table 1 shows the pneumatic tire 30 (FIG. 5) of the embodiment as Example 3-in and the pneumatic tire 40 (FIG. 8) of the third embodiment as Example 4-in.

  Further, as a modification of Example 1-in, a case in which deep groove bottoms 15A and 16A are formed on the tread grounding end 12E side as shown in FIG. 2 is referred to as Example 1-out. As a modification, a structure in which a deep groove bottom 15A is formed on the tread grounding end 12E side as shown in FIG. 2 is referred to as Example 2-out, and an inclined groove 15C in which the tread grounding end 12E side becomes deep as shown in FIG. -1, 16C-1 is configured as Example 3-out, and as a modified example of Example 4-in, deep groove bottoms 15F, 16F are configured on the tread grounding end 12E side as illustrated in FIG. This was designated Example 4-out.

  Further, as a modified example of Example 1-in, a case in which deep groove bottoms 15A and 16A are formed at the center of the groove as shown in FIG. As shown in FIG. 3, a deep groove bottom 15A is formed at the center of the groove as Example 2-cent, and an inclined groove 15C-1 in which the center of the groove is the deepest as shown in FIG. A structure in which 16C-2 is configured is referred to as Example 3-cent. As a modification of Example 4-in, a structure in which deep groove bottoms 15F and 16F are configured in the center of the groove as illustrated in FIG. Example 4-cent.

 The results of the test are as shown in Table 2. About evaluation, it performed by the level difference average value about each of the center block of a tread, and the second block (the 1st block 22B, the 2nd block 26B), and has shown with the index which made the level difference average value of the comparative example 100. . The index shows that the larger the value, the less the heel and toe wear and the better the result.

  As is apparent from Table 2, Examples 1 to 4 of the present invention have less heel and toe wear and less heel and toe wear than the comparative example. Further, in the second circumferential groove 15 and the third circumferential groove 16, when the groove bottom on the center block 24B side is deepened (Example 1-in to Example 4-in), heel and toe wear of the center block is caused. When the groove bottom on the tread ground contact end 12E side is deepened (Example 1-out to Example 4-out), it can be seen that the heel and toe wear of the second block is suppressed. Furthermore, in the 2nd circumferential groove 15 and the 3rd circumferential groove 16, when the groove bottom of the tire width direction center part is deepened (Example 1-cent-Example 4-cent), a center block and a second block It can be seen that the heel and toe wear of both of these is suppressed.

10 pneumatic tire 12 tread 14 first circumferential groove 15 second circumferential groove 15A deep groove bottom 15B shallow groove bottom 15C inclined bottom 15F deep groove bottom 15E shallow groove bottom 16 third circumferential groove 16A deep groove bottom 16E shallow groove bottom 16C inclined Bottom 17 Fourth circumferential groove 20 Horizontal groove 22 First land portion 22B First block 24 Center land portion 24B Center block 26 Second land portion 26B Second block

Claims (3)

A pneumatic tire having a plurality of circumferential grooves provided on a tread and extending along a tire circumferential direction and a block land portion defined by a plurality of lateral grooves extending in a direction intersecting the circumferential groove,
The groove bottom of the circumferential groove has a deep groove bottom and a shallow groove bottom shallower than the deep groove bottom, and the deep groove bottom has a width in the tire width direction that is the largest on the kicking side of the block land portion. The block land portion is formed on the tire equatorial plane side of the circumferential groove, which is wide and has a shape that becomes narrower as it approaches the stepping side of the block land portion, and divides the block land portion disposed on the tire equatorial plane. the formed adjacent pneumatic tire extending a distance from the block land portion of the trailing side is characterized by 10% to 100% der Rukoto, the total width of the circumferential groove. 2. The pneumatic tire according to claim 1, wherein the deep groove bottom has a triangular shape having a vertex on a stepping side of the block land portion in a plan view. The groove bottom depth of the shallowest part of the circumferential groove is 50% to 90% of the groove depth of the deepest part of the circumferential groove, according to claim 1 or 2 . Pneumatic tire.

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